WorldWideScience

Sample records for coupling tuning mechanisms

  1. On bandwidth characteristics of tuning fork micro-gyroscope with mechanically coupled sense mode.

    Science.gov (United States)

    Ni, Yunfang; Li, Hongsheng; Huang, Libin; Ding, Xukai; Wang, Haipeng

    2014-07-21

    The bandwidth characteristics of a tuning fork micro-gyroscope with mechanically coupled sense mode were investigated in this paper to provide some references for mechanical bandwidth design. The concept of sense mode mechanical coupling is introduced first. Theoretical frequency response analyses were then carried out on the mechanical part of the gyroscope. Equations representing the relationships between the differential output signal and the frequency of the input angular rate were deduced in full frequency range and further simplified in low frequency range. Based on these equations, bandwidth characteristics under ideal and non-ideal conditions are discussed. Analytical results show that under ideal conditions, the bandwidth characteristics of a tuning fork micro-gyroscope are similar to those of a single mass micro-gyroscope, but under non-ideal conditions, especially when sense mass and/or stiffness are asymmetric, the bandwidth characteristics would be quite different because the in-phase mode would participate in the anti-phase vibration response. Experimental verifications were carried out on two micro-gyroscope prototypes designed in our laboratory. The deduced equations and analytical results can be used in guiding the mechanical bandwidth design of tuning fork micro-gyroscopes with mechanically coupled sense mode.

  2. On Bandwidth Characteristics of Tuning Fork Micro-Gyroscope with Mechanically Coupled Sense Mode

    Directory of Open Access Journals (Sweden)

    Yunfang Ni

    2014-07-01

    Full Text Available The bandwidth characteristics of a tuning fork micro-gyroscope with mechanically coupled sense mode were investigated in this paper to provide some references for mechanical bandwidth design. The concept of sense mode mechanical coupling is introduced first. Theoretical frequency response analyses were then carried out on the mechanical part of the gyroscope. Equations representing the relationships between the differential output signal and the frequency of the input angular rate were deduced in full frequency range and further simplified in low frequency range. Based on these equations, bandwidth characteristics under ideal and non-ideal conditions are discussed. Analytical results show that under ideal conditions, the bandwidth characteristics of a tuning fork micro-gyroscope are similar to those of a single mass micro-gyroscope, but under non-ideal conditions, especially when sense mass and/or stiffness are asymmetric, the bandwidth characteristics would be quite different because the in-phase mode would participate in the anti-phase vibration response. Experimental verifications were carried out on two micro-gyroscope prototypes designed in our laboratory. The deduced equations and analytical results can be used in guiding the mechanical bandwidth design of tuning fork micro-gyroscopes with mechanically coupled sense mode.

  3. Towards Tuning the Mechanical Properties of Three-Dimensional Collagen Scaffolds Using a Coupled Fiber-Matrix Model

    Directory of Open Access Journals (Sweden)

    Shengmao Lin

    2015-08-01

    Full Text Available Scaffold mechanical properties are essential in regulating the microenvironment of three-dimensional cell culture. A coupled fiber-matrix numerical model was developed in this work for predicting the mechanical response of collagen scaffolds subjected to various levels of non-enzymatic glycation and collagen concentrations. The scaffold was simulated by a Voronoi network embedded in a matrix. The computational model was validated using published experimental data. Results indicate that both non-enzymatic glycation-induced matrix stiffening and fiber network density, as regulated by collagen concentration, influence scaffold behavior. The heterogeneous stress patterns of the scaffold were induced by the interfacial mechanics between the collagen fiber network and the matrix. The knowledge obtained in this work could help to fine-tune the mechanical properties of collagen scaffolds for improved tissue regeneration applications.

  4. High precision tune and coupling measurements and tune/coupling feedback in RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Minty, M.; Curcio, A.; Dawson, C.; Degen, C.; Luo, Y.; Marr, G.; Martin, B.; Marusic, A.; Mernick, K.; Oddo, P.; Russo, T.; Schoefer, V.; Schroeder, R.; Schulthiess, C.; Wilinski, M.

    2010-08-01

    Precision measurement and control of the betatron tunes and betatron coupling in RHIC are required for establishing and maintaining both good operating conditions and, particularly during the ramp to high beam energies, high proton beam polarization. While the proof-of-principle for simultaneous tune and coupling feedback was successfully demonstrated earlier, routine application of these systems has only become possible recently. Following numerous modifications for improved measurement resolution and feedback control, the time required to establish full-energy beams with the betatron tunes and coupling regulated by feedback was reduced from several weeks to a few hours. A summary of these improvements, select measurements benefitting from the improved resolution and a review of system performance are the subject of this report.

  5. Tuning intermetallic electronic coupling in polyruthenium systems ...

    Indian Academy of Sciences (India)

    A large number of polynuclear ruthenium complexes encompassing selective combinations of spacer (bridging ligand, BL) and ancillary (AL) functionalities have been designed. The extent of intermetallic electronic communication in mixed-valent states and the efficacy of the ligand frameworks towards the tuning of ...

  6. Frequency tuning and coherent dynamics of two nanostring resonators in the strong coupling regime

    Science.gov (United States)

    Huebl, Hans; Pernpeintner, Matthias; Schmidt, Philip; Schwienbacher, Daniel; Gross, Rudolf

    Coupled nanomechanical resonators are interesting model systems for studying synchronization effects and nonlinear dynamics. This, however, requires the possibility to tune the relevant mode frequencies independently and to operate the resonators in the strong coupling regime. Here, we present a possible realization consisting of two high-quality nanostring resonators, coupled mechanically by a shared support structure. First, we demonstrate that the fundamental mode frequencies of both nanostrings can be tuned independently by a strong drive tone resonant with one of the higher harmonic modes. This technique relies on an effective increase of the pre-stress in a highly excited nanobeam, known as geometric nonlinearity. Using this frequency tuning concept, we investigate the coherent dynamics of the two strongly coupled nanostring resonators. With the two nanobeams tuned in resonance, we observe oscillations corresponding to Rabi oscillations, which indicates coherent excitation transfer between the fundamental modes of the two nanostrings. In addition, experimental investigation of classical Landau-Zener dynamics demonstrates that this coupling and tuning concept paves the way for a selective phonon transfer between two spatially separated mechanical resonators. Nanosystems Initiative Munich.

  7. Tuning the effective spin-orbit coupling in molecular semiconductors

    KAUST Repository

    Schott, Sam

    2017-05-11

    The control of spins and spin to charge conversion in organics requires understanding the molecular spin-orbit coupling (SOC), and a means to tune its strength. However, quantifying SOC strengths indirectly through spin relaxation effects has proven difficult due to competing relaxation mechanisms. Here we present a systematic study of the g-tensor shift in molecular semiconductors and link it directly to the SOC strength in a series of high-mobility molecular semiconductors with strong potential for future devices. The results demonstrate a rich variability of the molecular g-shifts with the effective SOC, depending on subtle aspects of molecular composition and structure. We correlate the above g-shifts to spin-lattice relaxation times over four orders of magnitude, from 200 to 0.15 μs, for isolated molecules in solution and relate our findings for isolated molecules in solution to the spin relaxation mechanisms that are likely to be relevant in solid state systems.

  8. Tuning decoherence in superconducting transmon qubits by mechanical strain

    Energy Technology Data Exchange (ETDEWEB)

    Brehm, Jan; Bilmes, Alexander; Weiss, Georg; Ustinov, Alexey; Lisenfeld, Juergen [Karlsruher Institut fuer Technologie, Karlsruhe (Germany)

    2016-07-01

    Two-level tunneling systems (TLS) are formed by structural defects in disordered materials. They gained recent attention as an important decoherence source in superconducting qubits, where they appear on surface oxides and at film interfaces. Although the most advanced qubits do not show avoided level crossings arising from a strong coupling to individual TLS, they commonly display a pronounced frequency dependence of relaxation rates, with distinguishable peaks that may point towards weak resonant coupling to single TLS. Previously, we have shown that TLS are tunable via an applied mechanical strain. Here, we employ this method to test whether the characteristic decoherence spectrum of a transmon qubit sample responds to changes in the applied strain, as it can be expected when the decohering bath is formed of atomic TLS. In our experiment, we will employ a highly coherent X-mon qubit sample and tune the strain by bending the qubit chip via a piezo actuator. Our latest results will be presented.

  9. Tuning the mechanical properties of silica microcapsules

    NARCIS (Netherlands)

    Zhang, L.; D'Acunzi, M.; Kappl, M.; Imhof, A.; van Blaaderen, A.; Butt, H. -J; Graf, R.; Vollmer, D.

    2010-01-01

    Heat treatment is a standard method to increase the hardness of silica in various applications. Here, we tested the effect of high temperature annealing on the mechanical properties of silica microcapsules by force spectroscopy under point loads applied to the particle shell. The Young's modulus of

  10. Tuning Mechanisms in a Corrugated Origami Frequency Selective Surface (Preprint)

    Science.gov (United States)

    2017-07-09

    Xenia Rd, Beavercreek, OH 45432 4) Texas A&M University, Rudder Tower 401 Joe Routt Blvd., College Station, TX 77843 Standard Form 298...used to discuss the range of frequency tuning achievable. II. DESIGN AND SIMULATIONS A unit cell of the foldable FSS consists of two half...coupling effect between in- cell dipoles labeled 1 and 2 as well as inter- cell dipole 1 and 1* (or 2 and 2*). Full-wave computations are carried out

  11. Mechanical and electrical tuning in a tonotopically organized insect ear

    Science.gov (United States)

    Hummel, Jennifer; Schöneich, Stefan; Hedwig, Berthold; Kössl, Manfred; Nowotny, Manuela

    2015-12-01

    The high-frequency hearing organ of bushcrickets - the crista acustica (CA) - is tonotopically organized. Details about the mechano-electrical transduction mechanisms within the sensory-cell complex, however, remain unknown. In the recent study, we investigated and compared the anatomical, mechanical and electrophysiological properties of the CA and reveal a strong correlation of the mechanical and neuronal frequency tuning, which is supported by an anatomical gradient along the CA. Only in the distal high-frequency region of the CA a discrepancy between a strong mechanical response to low frequencies 30 kHz was found. Therefore, we suggest that there might be additional intrinsic tuning mechanisms in the sensory cells of the distal region to distinguish the frequency content of sound.

  12. Coupling and tuning of modal frequencies in direct current biased microelectromechanical systems arrays

    Energy Technology Data Exchange (ETDEWEB)

    Kambali, Prashant N.; Swain, Gyanadutta; Pandey, Ashok Kumar, E-mail: ashok@iith.ac.in [Department of Mechanical and Aerospace Engineering, IIT Hyderabad, Yeddumailaram 502205 (India); Buks, Eyal [Faculty of Electrical Engineering, Technion-Israel Institute of Technology, Haifa 32000 (Israel); Gottlieb, Oded [Faculty of Mechanical Engineering, Technion-Israel Institute of Technology, Haifa 32000 (Israel)

    2015-08-10

    Understanding the coupling of different modal frequencies and their tuning mechanisms has become essential to design multi-frequency MEMS devices. In this work, we fabricate a MEMS beam with fixed boundaries separated from two side electrodes and a bottom electrode. Subsequently, we perform experiments to obtain the frequency variation of in-plane and out-of-plane mechanical modes of the microbeam with respect to both DC bias and laser heating. We show that the frequencies of the two modes coincide at a certain DC bias, which in turn can also be varied due to temperature. Subsequently, we develop a theoretical model to predict the variation of the two modes and their coupling due to a variable gap between the microbeam and electrodes, initial tension, and fringing field coefficients. Finally, we discuss the influence of frequency tuning parameters in arrays of 3, 33, and 40 microbeams, respectively. It is also found that the frequency bandwidth of a microbeam array can be increased to as high as 25 kHz for a 40 microbeam array with a DC bias of 80 V.

  13. Cloud tuning in a coupled climate model: Impact on 20th century warming

    National Research Council Canada - National Science Library

    Golaz, Jean‐Christophe; Horowitz, Larry W; Levy, Hiram

    2013-01-01

    .... A given radiation balance can be achieved by multiple combinations of parameters. We investigate the impact of cloud tuning in the CMIP5 GFDL CM3 coupled climate model by constructing two alternate configurations...

  14. Coupling graphene mechanical resonators to superconducting microwave cavities.

    Science.gov (United States)

    Weber, P; Güttinger, J; Tsioutsios, I; Chang, D E; Bachtold, A

    2014-05-14

    Graphene is an attractive material for nanomechanical devices because it allows for exceptional properties, such as high frequencies, quality factors, and low mass. An outstanding challenge, however, has been to obtain large coupling between the motion and external systems for efficient readout and manipulation. Here, we report on a novel approach, in which we capacitively couple a high-Q graphene mechanical resonator (Q ≈ 10(5)) to a superconducting microwave cavity. The initial devices exhibit a large single-photon coupling of ∼10 Hz. Remarkably, we can electrostatically change the graphene equilibrium position and thereby tune the single photon coupling, the mechanical resonance frequency, and the sign and magnitude of the observed Duffing nonlinearity. The strong tunability opens up new possibilities, such as the tuning of the optomechanical coupling strength on a time scale faster than the inverse of the cavity line width. With realistic improvements, it should be possible to enter the regime of quantum optomechanics.

  15. Single tunable laser interrogation of slab-coupled optical sensors through resonance tuning.

    Science.gov (United States)

    Chadderdon, Spencer; Woodard, Leeland; Perry, Daniel; Selfridge, Richard H; Schultz, Stephen M

    2013-04-20

    This paper describes a method for tuning the resonant wavelengths of slab-coupled optical fiber sensors (SCOSs). This method allows multiple sensors to be interrogated simultaneously with a single tunable laser. The resonances are tuned by rotating a biaxial slab waveguide relative to an optical D-fiber. As the slab waveguide rotates, its effective index of refraction changes causing the coupling wavelengths of the slab waveguide and D-fiber to shift. A SCOS fabricated with potassium titanyl phosphate crystal as the slab waveguide is shown to have resonance tuning ranges of 6.67 and 22.24 nm, respectively, for TM and TE polarized modes.

  16. A New Tuning Module for Resonant Coupling Structures

    CERN Document Server

    Vaccaro, Vittorio G; De Martinis, Carlo; Giove, Dario; Masullo, Maria R; Mauri, Marco; Rainò, Antonio; Variale, Vincenzo

    2005-01-01

    In order to have efficient particle acceleration it is fundamental that the particles experience, in the accelerating gap, field amplitudes as uniform and as high as possible from gap to gap. Because of the unavoidable fabrication errors, an accelerating structure, when assembled, exhibits field values lower than the nominal ones and/or not uniform. All the usual procedures developed in order to adjust the parameter deviations responsible of the malfunction of these structures, are based on field amplitude measurements, by using the bead pull technique, which is a very invasive technique. In this paper the philosophy is reversed: it is assumed that all the information can be got by Sounding the Modes of the whole System (SMS) and correct the deviation of each frequency mode from its nominal value by means of an appropriate tuning of the cavities: resorting to a perturbative technique applied to a circuit model representing this kind of structures, it is possible to calculate the amount of tuning to give to th...

  17. A study on the field tuning method of a resonantly coupled RFQ

    CERN Document Server

    Fu Shin Ian

    2002-01-01

    Resonantly coupled RFQ is commonly used as the low-energy accelerating structure for an intense-beam proton linac. It is essential that the field distribution meets the design requirement in order to minimize the beam losses. Based on the RFQ transmission line model, a study on the field tuning was conducted on the cold model RFQ, focusing on the characteristics of the resonantly coupled RFQ structure. A satisfactory result was achieved in the field stabilization, and meanwhile it also demonstrated the validity of the RFQ tuning code made on the platform of LabView

  18. Discrete Vernier tuning in terahertz quantum cascade lasers using coupled cavities.

    Science.gov (United States)

    Kundu, Iman; Dean, Paul; Valavanis, Alexander; Chen, Li; Li, Lianhe; Cunningham, John E; Linfield, Edmund H; Davies, A Giles

    2014-06-30

    Discrete Vernier frequency tuning of terahertz quantum cascade lasers is demonstrated using a device comprising a two-section coupled-cavity. The two sections are separated by a narrow air gap, which is milled after device packaging using a focused ion beam. One section of the device (the lasing section) is electrically biased above threshold using a short current pulse, while the other section (the tuning section) is biased below threshold with a wider current pulse to achieve controlled localized electrical heating. The resulting thermally-induced shift in the longitudinal cavity modes of the tuning section is engineered to produce either a controllable blue shift or red shift of the emission frequency. This discrete Vernier frequency tuning far exceeds the tuning achievable from standard ridge lasers, and does not lead to any corresponding change in emitted power. Discrete tuning was observed over bandwidths of 50 and 85 GHz in a pair of devices, each using different design schemes. Interchanging the lasing and tuning sections of the same devices yielded red shifts of 20 and 30 GHz, respectively.

  19. Frequency tuning and stability of Nd:YVO4 in a dual coupled cavity

    DEFF Research Database (Denmark)

    Hansen, P. L.; Pedersen, Christian; Buchhave, Preben

    1996-01-01

    Frequency tuning and stability properties of single- and multi-cavity designs have been investigated theoretically and experimentally. Special attention is paid to a dual coupled cavity single-frequency diode-pumped solid-state Nd:YVO4 laser crystal. 350 mW single frequency output power has...

  20. Understanding the Tune, Coupling, and Chromaticity Dependence of the LHC on Landau Octupole Powering

    CERN Document Server

    Maclean, E; Herr, W; Levinsen, Y; Papotti, G; Persson, T; Skowronski, P; Tomas, R; Wenninger, J

    2013-01-01

    During the 2012 LHC run observations were made of shifts to tune, coupling and chromaticity (Q, Q′ and |C−|) which were correlated with changes in the powering of Landau octupoles. We summarize the observations and describe our understanding to-date of the relationship between Q, Q′, |C−| and Landau octupole powering.

  1. Electronic tuning of integrated blue-violet GaN tunable coupled-cavity laser

    NARCIS (Netherlands)

    Guziy, O.; Grzanka, S.; Leszczynski, M.; Perlin, P.; Schemmann, M.; Salemink, H.W.M.

    2012-01-01

    We demonstrate an integrated tunable coupled-cavity InGaN/GaN laser with the emission wavelength centered on 409 nm. The electronic tuning range was 1.6 nm and threshold currents were 650 mA per cavity for 8.7-?m-wide laser ridges. Multimode laser emission with an average full width at half maximum

  2. Tuning and stability properties of a single frequency diode-pumped coupled-cavity Nd:YVO4 laser

    DEFF Research Database (Denmark)

    Lichtenberg Hansen, Peter; Pedersen, Christian; Skettrup, Torben

    1996-01-01

    Frequency tuning of a coupled cavity solid-state Nd:YVO4 laser has been investigated boththeoretically and experimentally. The frequency tuning curve was calculated from equationsdescribing the normalized circulating field (enhancement) of a coupled cavity introducing aLorentzian gain profile...

  3. Phase tuning in two-dimensional coherently coupled vertical-cavity surface-emitting laser array.

    Science.gov (United States)

    Xun, Meng; Xu, Chen; Xie, Yiyang; Deng, Jun; Jiang, Guoqing; Pan, Guanzhong; Dong, Yibo; Chen, Hongda

    2016-07-10

    Implant-defined vertical-cavity surface-emitting laser (VCSEL) arrays can be designed to operate in in-phase mode. However, the nonuniformities in fabrication process impact the resonance selection and the devices do not follow expected trends. Coherent coupling was demonstrated in three-element VCSEL arrays via phase tuning of elements. In-phase mode and out-of-phase mode were both achieved in most of the arrays. Moreover, coherent coupling can decrease the threshold current of elements in the array. Improved output power was also clearly observed when the array operated in the in-phase mode. Arbitrary phase combination of the array elements can be obtained via the phase tuning. This technology is able to improve the reproducibility and practicability of the implant-defined coherently coupled VCSEL array.

  4. Coupled-mode-induced transparency in aerostatically tuned microbubble whispering-gallery resonators.

    Science.gov (United States)

    Yang, Yong; Saurabh, Sunny; Ward, Jonathan; Chormaic, Síle Nic

    2015-04-15

    Coupled-mode-induced transparency is realized in a single microbubble whispering-gallery mode resonator. Using aerostatic tuning, we find that the pressure-induced shifting rates are different for different radial order modes. A finite element simulation considering both the strain and stress effects shows a GHz/bar difference, and this is confirmed by experiments. A transparency spectrum is obtained when a first-order mode shifts across a higher order mode through precise pressure tuning. The resulting lineshapes are fitted with the theory. This work lays a foundation for future applications in microbubble sensing.

  5. Coupled-mode induced transparency in aerostatically-tuned microbubble whispering gallery resonators

    CERN Document Server

    Yang, Yong; Ward, Jonathan; Chormaic, Síle Nic

    2015-01-01

    Coupled-mode induced transparency is realized in a single microbubble whispering gallery mode resonator. Using aerostatic tuning, we find that the pressure induced shifting rates are different for different radial order modes. A finite element simulation considering both the strain and stress effects shows a GHz/bar difference and this is confirmed by experiments. A transparency spectrum is obtained when a first order mode shifts across a higher order mode through precise pressure tuning. The resulting lineshapes are fitted with the theory. This work lays a foundation for future applications in microbubble sensing.

  6. Dynamic Tuning of Plasmon-Exciton Coupling in Arrays of Nanodisk-J-aggregate Complexes

    KAUST Repository

    Zheng, Yue Bing

    2010-07-21

    Figure Presented Dynamic tuning of plasmon-exclton resonant coupling in arrays of nanodisk-J-aggregate complexes is demonstrated. The angle-resolved spectra of an array of bare gold nanodisks exhibit continuous shifting of localized surface plasmon resonance. This characteristic enables the production of real-time, controllable spectral overlap between molecular resonance and plasmóme resonance. The resonant interaction strength as a function of spectral overlap is explored and the coupling strength changes with the incident angle of a probe light, in accord with simulations based on coupled dipóle approximation method. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Frequency-Splitting-Free Synchronous Tuning of Close-Coupling Self-Oscillating Wireless Power Transfer

    Directory of Open Access Journals (Sweden)

    Po Hu

    2016-06-01

    Full Text Available The synchronous tuning of the self-oscillating wireless power transfer (WPT in a close-coupling condition is studied in this paper. The Hamel locus is applied to predict the self-oscillating points in the WPT system. In order to make the system operate stably at the most efficient point, which is the middle resonant point when there are middle resonant and split frequency points caused by frequency-splitting, the receiver (RX rather than the transmitter (TX current is chosen as the self-oscillating feedback variable. The automatic delay compensation is put forward to eliminate the influence of the intrinsic delay on frequency tuning for changeable parameters. In addition, the automatic circuit parameter tuning based on the phase difference is proposed to realize the synchronous tuning of frequency and circuit parameters. The experiments verified that the synchronous tuning proposed in this paper is effective, fully automatic, and more robust than the previous self-oscillating WPT system which use the TX current as the feedback variable.

  8. Understanding the tune, coupling, and chromaticity dependence of the LHC on Landau octupole powering.

    CERN Document Server

    Maclean, E H; Persson, T; Tomas, R; Wenninger, J

    2013-01-01

    During the 2012 LHC run several observations were made of shifts to tune, coupling and chromaticity which were correlated with changes in the powering of Landau octupoles. Understanding the chromaticity dependence is of particular importance given its influence on instabilities. This note briefly summarizes the observations and describes our understanding to-date of the relationship between Q, Q′, |C−| and the Landau octupole powering.

  9. Plasmon-phonon coupled modes in graphene tuned by the carrier concentration of the semiconductor substrates

    OpenAIRE

    Wang, Lei; Cai, Wei; Zhang, Xinzheng; Xu, Jingjun

    2014-01-01

    The interaction between graphene plasmons and surface phonons of a semiconductor substrate is investigated, which can be efficiently controlled by the carrier injection of the substrate. The energy and lifetime of surface phonons in a substrate depend a lot on the carrier concentration, which provides a new machanism to tune plasmon-phonon coupled modes (PPCMs). More specifically, the dispersion and lifetime of PPCMs can be controlled by the carrier concentration change of the substrate. The ...

  10. Studies of the Chromaticity, Tune, and Coupling Drift in the Tevatron

    CERN Document Server

    Martens, Michael A; Bauer, Pierre; Shiltsev, Vladimir; Velev, Gueorgui

    2005-01-01

    Chromaticity drift is a well-known and more or less well-understood phenomenon in superconducting colliders such as the Tevatron. Less known is the effect of tune and coupling drift, also observed in the Tevatron during injection. These effects are caused by field drifts in the superconducting magnets. Understanding of the behavior of the tune, coupling, and chromaticity at the start of the ramp is an important part of understanding the observed 5-10% loss in beam intensity at the start of the Tevatron ramp. In addition modifications in the Tevatron shot set-up procedure are being implemented to allow for a gain in integrated luminosity. In this context we conducted several beam-studies, during the period of April to August 2004, in which we measured the drift in the Tevatron chromaticity, tune and coupling during the injection porch. In some case we also measured the snapback at the start of the ramp. We will present the results of these studies data and put them into context of the results of off-line magne...

  11. Coupling element antenna with slot tuning for handheld devices at LTE frequencies

    DEFF Research Database (Denmark)

    Barrio, Samantha Caporal Del; Pelosi, Mauro; Franek, Ondrej

    2012-01-01

    . A reconfigurable slot is inserted in the ground plane in order to lower its resonance frequency. The tuning is done by a capacitor across the slot. It is shown that covering all frequencies between the 900-GSM band and the 700-LTE band can be achieved. The radiating structure also presents a resonance in the high...... LTE band which is unaffected by the tuning mechanism of the lower band. Moreover, the efficiency can be optimized by an analysis of the currents across the slot. The study also shows that holding the device does not lead to additional mismatch losses which will further improve the overall efficiency....

  12. An electrical tuning mechanism in turtle cochlear hair cells.

    Science.gov (United States)

    Crawford, A C; Fettiplace, R

    1981-03-01

    through the same micropipette, failed to produce any change in the auditory nerve discharge. The experiment demonstrates that current injection does not produce gross movements of the electrode tip.7. The contribution of the electrical resonance to hair-cell tuning was assessed by dividing the linear tuning curve by the cell's impedance as a function of frequency. The procedure assumes that the electrical resonance is independent of other filtering stages, and on this assumption the resonance can account for the tip of the acoustical tuning curve.8. The residual filter produced by the division was broad; it exhibited a high-frequency roll-off with a corner frequency at 500-600 Hz, similar in all cells, and a low-frequency roll-off, with a corner frequency from 30 to 350 Hz which varied from cell to cell but was uncorrelated with the characteristic frequency of the cell.9. The phase of the receptor potential relative to the sound pressure at the tympanum was measured in ten cells. For low intensities the phase characteristic was independent of the sound pressure. At low frequencies the receptor potential led the sound by 270-360 degrees , and in the region of the characteristic frequency there was an abrupt phase lag of 90-180 degrees ; the abruptness of the phase change depended upon the Q of the cell.10. The calculated phase shift of the electrical resonator as a function of frequency was subtracted from the phase characteristic of the receptor potential. The subtraction removed the sharp phase transition around the characteristic frequency, and in this frequency region the residual phase after subtraction was approximately constant at +180 degrees . This is consistent with the idea that the hair cells depolarize in response to displacements of the basilar membrane towards the scala vestibuli. The high-frequency region of the residual phase characteristic was similar in all cells.11. It is concluded that each hair cell contains its own electrical resonance mechanism

  13. Tuned and Balanced Redistributed Charge Scheme for Combined Quantum Mechanical and Molecular Mechanical (QM/MM) Methods and Fragment Methods: Tuning Based on the CM5 Charge Model.

    Science.gov (United States)

    Wang, Bo; Truhlar, Donald G

    2013-02-12

    Tuned and balanced redistributed charge schemes have been developed for modeling the electrostatic fields of bonds that are cut by a quantum mechanical-molecular mechanical boundary in combined quantum mechanical and molecular mechanical (QM/MM) methods. First, the charge is balanced by adjusting the charge on the MM boundary atom to conserve the total charge of the entire QM/MM system. In the balanced smeared redistributed charge (BSRC) scheme, the adjusted MM boundary charge is smeared with a smearing width of 1.0 Å and is distributed in equal portions to the midpoints of the bonds between the MM boundary atom and the MM atoms bonded to it; in the balanced redistributed charge-2 (BRC2) scheme, the adjusted MM boundary charge is distributed as point charges in equal portions to the MM atoms that are bonded to the MM boundary atom. The QM subsystem is capped by a fluorine atom that is tuned to reproduce the sum of partial atomic charges of the uncapped portion of the QM subsystem. The new aspect of the present study is a new way to carry out the tuning process; in particular, the CM5 charge model, rather than the Mulliken population analysis applied in previous studies, is used for tuning the capping atom that terminates the dangling bond of the QM region. The mean unsigned error (MUE) of the QM/MM deprotonation energy for a 15-system test suite of deprotonation reactions is 2.3 kcal/mol for the tuned BSRC scheme (TBSRC) and 2.4 kcal/mol for the tuned BRC2 scheme (TBRC2). As was the case for the original tuning method based on Mulliken charges, the new tuning method performs much better than using conventional hydrogen link atoms, which have an MUE on this test set of about 7 kcal/mol. However, the new scheme eliminates the need to use small basis sets, which can be problematic, and it allows one to be more consistent by tuning the parameters with whatever basis set is appropriate for applications. (Alternatively, since the tuning parameters and partial charges

  14. Distortion mechanisms in varactor diode-tuned microwave filters

    OpenAIRE

    Carey-Smith, BE; Warr, PA

    2006-01-01

    This paper examines the broadband distortion behavior in flexible filters employing varactor-diode tuning elements. Series- and parallel-resonant varactor-loaded transmission-lines, both commonly used in bandpass and bandstop microwave filters, are analyzed. Nonlinear Volterra-series analysis is employed to determine the second- and third-order distortion ratios dependent on the frequencies of the incident signals. It is shown that in a bandpass filter (employing parallel tuned resonators), m...

  15. Structural Interplay - Tuning Mechanics in Peptide-Polyurea Hybrids

    Science.gov (United States)

    Korley, Lashanda

    Utilizing cues from natural materials, we have been inspired to explore the hierarchical arrangement critical to energy absorption and mechanical enhancement in synthetic systems. Of particular interest is the soft domain ordering proposed as a contributing element to the observed toughness in spider silk. Multiblock copolymers, are ideal and dynamic systems in which to explore this approach via variations in secondary structure of nature's building blocks - peptides. We have designed a new class of polyurea hybrids that incorporate peptidic copolymers as the soft segment. The impact of hierarchical ordering on the thermal, mechanical, and morphological behavior of these bio-inspired polyurethanes with a siloxane-based, peptide soft segment was investigated. These peptide-polyurethane/urea hybrids were microphase segregated, and the beta-sheet secondary structure of the soft segment was preserved during polymerization and film casting. Toughness enhancement at low strains was achieved, but the overall extensibility of the peptide-incorporated systems was reduced due to the unique hard domain organization. To decouple the secondary structure influence in the siloxane-peptide soft segment from mechanics dominated by the hard domain, we also developed non-chain extended peptide-polyurea hybrids in which the secondary structure (beta sheet vs. alpha helix) was tuned via choice of peptide and peptide length. It was shown that this structural approach allowed tailoring of extensibility, toughness, and modulus. The sheet-dominant hybrid materials were typically tougher and more elastic due to intermolecular H-bonding facilitating load distribution, while the helical-prevalent systems generally exhibited higher stiffness. Recently, we have explored the impact of a molecular design strategy that overlays a covalent and physically crosslinked architecture in these peptide-polyurea hybrids, demonstrating that physical constraints in the network hybrids influences peptide

  16. Detecting shapes in noise: tuning characteristics of global shape mechanisms

    Science.gov (United States)

    Schmidtmann, Gunnar; Gordon, Gael E.; Bennett, David M.; Loffler, Gunter

    2013-01-01

    The proportion of signal elements embedded in noise needed to detect a signal is a standard tool for investigating motion perception. This paradigm was applied to the shape domain to determine how local information is pooled into a global percept. Stimulus arrays consisted of oriented Gabor elements that sampled the circumference of concentric radial frequency (RF) patterns. Individual Gabors were oriented tangentially to the shape (signal) or randomly (noise). In different conditions, signal elements were located randomly within the entire array or constrained to fall along one of the concentric contours. Coherence thresholds were measured for RF patterns with various frequencies (number of corners) and amplitudes (“sharpness” of corners). Coherence thresholds (about 10% = 15 elements) were lowest for circular shapes. Manipulating shape frequency or amplitude showed a range where thresholds remain unaffected (frequency ≤ RF4; amplitude ≤ 0.05). Increasing either parameter caused thresholds to rise. Compared to circles, thresholds increased by approximately four times for RF13 and five times for amplitudes of 0.3. Confining the signals to individual contours significantly reduced the number of elements needed to reach threshold (between 4 and 6), independent of the total number of elements on the contour or contour shape. Finally, adding external noise to the orientation of the elements had a greater effect on detection thresholds than adding noise to their position. These results provide evidence for a series of highly sensitive, shape-specific analysers which sum information globally but only from within specific annuli. These global mechanisms are tuned to position and orientation of local elements from which they pool information. The overall performance for arrays of elements can be explained by the sensitivity of multiple, independent concentric shape detectors rather than a single detector integrating information widely across space (e.g. Glass

  17. Dielectric tuning and coupling of whispering gallery modes using an anisotropic prism

    CERN Document Server

    Foreman, Matthew R; Schwefel, Harald G L; Leuchs, Gerd

    2016-01-01

    Optical whispering gallery mode (WGM) resonators are a powerful and versatile tool used in many branches of science. Fine tuning of the central frequency and line width of individual resonances is however desirable in a number of applications including frequency conversion, optical communications and efficient light-matter coupling. To this end we present a detailed theoretical analysis of dielectric tuning of WGMs supported in axisymmetric resonators. Using the Bethe-Schwinger equation and adopting an angular spectrum field representation we study the resonance shift and mode broadening of high $Q$ WGMs when a planar dielectric substrate is brought close to the resonator. Particular focus is given to use of a uniaxial substrate with an arbitrarily aligned optic axis. Competing red and blue resonance shifts ($\\sim 30$ MHz), deriving from generation of a near field material polarisation and back action from the radiation continuum respectively, are found. Anomalous resonance shifts can hence be observed depend...

  18. Increasing light coupling in a photovoltaic film by tuning nanoparticle shape with substrate surface energy

    Science.gov (United States)

    Kataria, Devika; Krishnamoorthy, Kothandam; Iyer, S. Sundar Kumar

    2017-08-01

    Tuning metal nanoparticle (MNP) contact angle on the surface it is formed can help maximise the useful optical coupling in photovoltaic films by localized surface plasmon (LSP) resonance—opening up the possibility of building improved photovoltaic cells. In this work experimental demonstration of optical absorption increase in copper phthalocyanine (CuPc) films by tuning silver MNP shape by changing its contact angles with substrate has been reported. Thin films of poly3,4 ethylenedioxythiophene: sodium dodecycl sulphate (PEDOT:SDS) with different surface energies were formed on indium tin oxide (ITO) coated glass by electro-deposition. Silver MNPs thermally evaporated directly on ozonised ITO as well as on the PEDOT:SDS films showed contact angles ranging from 60° to 125°. The CuPc layer was deposited on top of the MNPs. For the samples studied, best optical absorption in the CuPc layer was for a contact angle of 110°.

  19. Coupled Acoustic-Mechanical Bandgaps

    DEFF Research Database (Denmark)

    Jensen, Jakob Søndergaard; Kook, Junghwan

    2016-01-01

    In this work, we study the existence of coupled bandgaps for corrugated plate structures and acoustic channels. The study is motivated by the observation that the performance of traditional bandgap structures, such as periodic plates, may be compromised due to the coupling to a surrounding acoust...... domains into account. Additionally, the coupling is shown to introduce extra gaps in the band structure due to modal interaction and the appearance of a cut-on frequency for the fundamental acoustic mode.......In this work, we study the existence of coupled bandgaps for corrugated plate structures and acoustic channels. The study is motivated by the observation that the performance of traditional bandgap structures, such as periodic plates, may be compromised due to the coupling to a surrounding acoustic...... medium and the presence of acoustic resonances. It is demonstrated that corrugation of the plate structure can introduce bending wave bandgaps and bandgaps in the acoustic domain in overlapping and audible frequency ranges. This effect is preserved also when taking the physical coupling between the two...

  20. Tuning the piezoelectric and mechanical properties of the AlN system via alloying with YN and BN

    Science.gov (United States)

    Manna, Sukriti; Brennecka, Geoff L.; Stevanović, Vladan; Ciobanu, Cristian V.

    2017-09-01

    Recent advances in microelectromechanical systems often require multifunctional materials, which are designed so as to optimize more than one property. Using density functional theory calculations for alloyed nitride systems, we illustrate how co-alloying a piezoelectric material (AlN) with different nitrides helps tune both its piezoelectric and mechanical properties simultaneously. Wurtzite AlN-YN alloys display increased piezoelectric response with YN concentration, accompanied by mechanical softening along the crystallographic c direction. Both effects increase the electromechanical coupling coefficients relevant for transducers and actuators. Resonator applications, however, require superior stiffness, thus leading to the need to decouple the increased piezoelectric response from the softened lattice. We show that co-alloying of AlN with YN and BN results in improved elastic properties while retaining some of the piezoelectric enhancements from YN alloying. This finding may lead to new avenues for tuning the design properties of piezoelectrics through composition-property maps.

  1. Tuning the effective coupling of an AFM lever to a thermal bath

    Energy Technology Data Exchange (ETDEWEB)

    Jourdan, G [Institut Neel CNRS Grenoble BP 166 38042, Grenoble Cedex 9 (France); Torricelli, G [Department of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom); Chevrier, J [Institut Neel CNRS Grenoble BP 166 38042, Grenoble Cedex 9 (France); Comin, F [ESRF, 6 rue Jules Horowitz, BP220, 38043 Grenoble Cedex (France)

    2007-11-28

    Fabrication of high quality nano-electromechanical systems (NEMS) is nowadays extremely efficient. These NEMS will be used as sensors and actuators in integrated systems. Their use, however, raises questions about their interface (actuation, detection, read out) with external detection and control systems. Their operation implies many fundamental questions related to single particle effects such as Coulomb blockade, light matter interactions such as radiation pressure, thermal effects, Casimir forces and the coupling of nanosystems to the external world (thermal fluctuations, back action effect). Here we specifically present how the damping of an oscillating cantilever can be tuned in two radically different ways: (i) through an electromechanical coupling in the presence of a strong Johnson noise, (ii) through an external feedback control of thermal fluctuations which is the cold damping closely related to Maxwell's demon. This shows how the interplay between external control of micro-EMS (MEMS) or NEMS and their coupling to a thermal bath can lead to a wealth of effects that are nowadays extensively studied in different areas.

  2. Tuning Cell and Tissue Development by Combining Multiple Mechanical Signals.

    Science.gov (United States)

    Sinha, Ravi; Verdonschot, Nico; Koopman, Bart; Rouwkema, Jeroen

    2017-10-01

    Mechanical signals offer a promising way to control cell and tissue development. It has been established that cells constantly probe their mechanical microenvironment and employ force feedback mechanisms to modify themselves and when possible, their environment, to reach a homeostatic state. Thus, a correct mechanical microenvironment (external forces and mechanical properties and shapes of cellular surroundings) is necessary for the proper functioning of cells. In vitro or in the case of nonbiological implants in vivo, where cells are in an artificial environment, addition of the adequate mechanical signals can, therefore, enable the cells to function normally as in vivo. Hence, a wide variety of approaches have been developed to apply mechanical stimuli (such as substrate stretch, flow-induced shear stress, substrate stiffness, topography, and modulation of attachment area) to cells in vitro. These approaches have not just revealed the effects of the mechanical signals on cells but also provided ways for probing cellular molecules and structures that can provide a mechanistic understanding of the effects. However, they remain lower in complexity compared with the in vivo conditions, where the cellular mechanical microenvironment is the result of a combination of multiple mechanical signals. Therefore, combinations of mechanical stimuli have also been applied to cells in vitro. These studies have had varying focus-developing novel platforms to apply complex combinations of mechanical stimuli, observing the co-operation/competition between stimuli, combining benefits of multiple stimuli toward an application, or uncovering the underlying mechanisms of their action. In general, they provided new insights that could not have been predicted from previous knowledge. We present here a review of several such studies and the insights gained from them, thereby making a case for such studies to be continued and further developed.

  3. Tuning the separation and coupling of corannulene trianion-radicals through sizable alkali metal belts.

    Science.gov (United States)

    Spisak, Sarah N; Rogachev, Andrey Yu; Zabula, Alexander V; Filatov, Alexander S; Clérac, Rodolphe; Petrukhina, Marina A

    2017-04-01

    The first heterobimetallic sandwich-type aggregate formed by bowl-shaped corannulene trianion-radicals, C20H10˙3-, has been synthesized using mixed-metal reduction of C20H10. The product was crystallographically characterized to reveal the self-assembly of [Cs+//(C20H103-)/4K+/(C20H103-)//Cs+], in which two triply-charged corannulene decks encapsulate a rectangle of four potassium ions (the K···K separations are 4.212(4) and 5.185(4) Å), with the exterior concave bowl cavities being selectively filled by one cesium ion each. In order to provide insights into the geometrical features and electronic structure of this novel mixed-metal organometallic self-assembly, an in-depth theoretical investigation has been carried out. Specifically, the influence of internal metal binding on the geometry and magnetic coupling of C20H10˙3- radicals is investigated for Group 1 metals. This study reveals that replacement of the sandwiched potassium ions with larger (Cs) and smaller (Li) ions allows variation of the size of the encapsulated metal belts, and thus enables tuning of the coupling of C20H10˙3- radicals.

  4. Tuning Acoustic Wave Properties by Mechanical Resonators on a Surface

    DEFF Research Database (Denmark)

    Dühring, Maria Bayard; Laude, Vincent; Khelif, Abdelkrim

    Vibrations generated by high aspects ratio electrodes are studied by the finite element method. It is found that the modes are combined of a surface wave and vibration in the electrodes. For increasing aspect ratio most of the mechanical energy is confined to the electrodes which act as mechanical...... resonators and slow down the velocity. It is furthermore found that the group delay can be increased compared to conventional thin electrodes. These results are interesting for filters and resonators as well as for delay lines....

  5. Molecular-level Insight into the Spectral Tuning Mechanism of the DsRed Chromophore

    DEFF Research Database (Denmark)

    List, Nanna Holmgaard; Olsen, Jógvan Magnus Haugaard; Jensen, Hans Jørgen Aagaard

    2012-01-01

    We present a detailed study of the protein environmental effects on the one- and twophoton absorption (1PA and 2PA, respectively) properties of the S0-S1 transition in the DsRed protein using the polarizable embedding density functional theory formalism. We find that steric factors and chromophore...... the protein. Our results indicate that this mainly is attributable to counter-directional contributions stemming from Lys163 and the conserved Arg95 with the former additionally identified as a key residue in the color tuning mechanism. The results provide new insights into the tuning mechanism of Ds...

  6. KINETICS AND MECHANISM OF THE DIAZO COUPLING ...

    African Journals Online (AJOL)

    rates of this acid catalyzed reaction in dioxane — water, ethanol — water. and propan—2—ol — water ... Recently we proposed a mechanism for the diazo coupling reaction of arenediazo methyl others with B—naphthol, as a ... The available results emphasise the highly basic character of water when compared to dioxane ...

  7. Slab thickness tuning approach for solid-state strong coupling between photonic crystal slab nanocavity and a quantum dot.

    Science.gov (United States)

    Chen, Gengyan; Liu, Jing-Feng; Jiang, Haoxiang; Zhuo, Xiao-Lu; Yu, Yi-Cong; Jin, Chongjun; Wang, Xue-Hua

    2013-04-23

    The quality factor and mode volume of a nanocavity play pivotal roles in realizing the strong coupling interaction between the nanocavity mode and a quantum dot. We present an extremely simple method to obtain the mode volume and investigate the effect of the slab thickness on the quality factor and mode volume of photonic crystal slab nanocavities. We reveal that the mode volume is approximatively proportional to the slab thickness. As compared with the previous structure finely optimized by introducing displacement of the air holes, via tuning the slab thickness, the quality factor can be enhanced by about 22%, and the ratio between the coupling coefficient and the nanocavity decay rate can be enhanced by about 13%. This can remarkably enhance the capability of the photonic crystal slab nanocavity for realizing the strong coupling interaction. The slab thickness tuning approach is feasible and significant for the experimental fabrication of the solid-state nanocavities.

  8. Halides tuning the subcellular-targeting in two-photon emissive complexes via different uptake mechanisms.

    Science.gov (United States)

    Tian, Xiaohe; Zhu, Yingzhong; Zhang, Qiong; Zhang, Ruilong; Wu, Jieying; Tian, Yupeng

    2017-07-11

    We reported a simple and universal strategy by tuning halides (Cl, Br and I) in terpyridine-Zn(ii) complexes to achieve different subcellular organelle targeting (nucleolus, nucleus and intracellular membrane systems, respectively) via different cellular uptake mechanisms, resulting from halide triggering different polymorphs of these complexes.

  9. Engine Tune-up Service. Unit 6: Emission Control Systems. Student Guide. Automotive Mechanics Curriculum.

    Science.gov (United States)

    Bacon, E. Miles

    This student guide is for Unit 6, Emission Control Systems, in the Engine Tune-Up Service portion of the Automotive Mechanics Curriculum. It deals with inspecting, testing, and servicing an emission control system. A companion review exercise book and posttests are available separately as CE 031 221-222. An introduction tells how this unit fits…

  10. A novel auto-tuning PID control mechanism for nonlinear systems.

    Science.gov (United States)

    Cetin, Meric; Iplikci, Serdar

    2015-09-01

    In this paper, a novel Runge-Kutta (RK) discretization-based model-predictive auto-tuning proportional-integral-derivative controller (RK-PID) is introduced for the control of continuous-time nonlinear systems. The parameters of the PID controller are tuned using RK model of the system through prediction error-square minimization where the predicted information of tracking error provides an enhanced tuning of the parameters. Based on the model-predictive control (MPC) approach, the proposed mechanism provides necessary PID parameter adaptations while generating additive correction terms to assist the initially inadequate PID controller. Efficiency of the proposed mechanism has been tested on two experimental real-time systems: an unstable single-input single-output (SISO) nonlinear magnetic-levitation system and a nonlinear multi-input multi-output (MIMO) liquid-level system. RK-PID has been compared to standard PID, standard nonlinear MPC (NMPC), RK-MPC and conventional sliding-mode control (SMC) methods in terms of control performance, robustness, computational complexity and design issue. The proposed mechanism exhibits acceptable tuning and control performance with very small steady-state tracking errors, and provides very short settling time for parameter convergence. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.

  11. Topological phase transitions in thin films by tuning multivalley boundary-state couplings

    Science.gov (United States)

    Li, Xiao; Niu, Qian

    2017-06-01

    Dirac boundary states on opposite boundaries can overlap and interact owing to finite size effect. We propose that in a thin film system with symmetry-unrelated valleys, valley-contrasting couplings between Dirac boundary states can be exploited to design various two-dimensional topological quantum phases. Our first-principles calculations demonstrate the mechanism in tin telluride slab and nanoribbon array, respectively, by top-down and bottom-up material designs. Both two-dimensional topological crystalline insulator and quantum spin Hall insulator emerge in the same material system, which offers highly tunable quantum transport of edge channels with a set of quantized conductances.

  12. Interval tuning in the primate medial premotor cortex as a general timing mechanism.

    Science.gov (United States)

    Merchant, Hugo; Pérez, Oswaldo; Zarco, Wilbert; Gámez, Jorge

    2013-05-22

    The precise quantification of time during motor performance is critical for many complex behaviors, including musical execution, speech articulation, and sports; however, its neural mechanisms are primarily unknown. We found that neurons in the medial premotor cortex (MPC) of behaving monkeys are tuned to the duration of produced intervals during rhythmic tapping tasks. Interval-tuned neurons showed similar preferred intervals across tapping behaviors that varied in the number of produced intervals and the modality used to drive temporal processing. In addition, we found that the same population of neurons is able to multiplex the ordinal structure of a sequence of rhythmic movements and a wide range of durations in the range of hundreds of milliseconds. Our results also revealed a possible gain mechanism for encoding the total number of intervals in a sequence of temporalized movements, where interval-tuned cells show a multiplicative effect of their activity for longer sequences of intervals. These data suggest that MPC is part of a core timing network that uses interval tuning as a signal to represent temporal processing in a variety of behavioral contexts where time is explicitly quantified.

  13. Energy coupling mechanisms of MFS transporters.

    Science.gov (United States)

    Zhang, Xuejun C; Zhao, Yan; Heng, Jie; Jiang, Daohua

    2015-10-01

    Major facilitator superfamily (MFS) is a large class of secondary active transporters widely expressed across all life kingdoms. Although a common 12-transmembrane helix-bundle architecture is found in most MFS crystal structures available, a common mechanism of energy coupling remains to be elucidated. Here, we discuss several models for energy-coupling in the transport process of the transporters, largely based on currently available structures and the results of their biochemical analyses. Special attention is paid to the interaction between protonation and the negative-inside membrane potential. Also, functional roles of the conserved sequence motifs are discussed in the context of the 3D structures. We anticipate that in the near future, a unified picture of the functions of MFS transporters will emerge from the insights gained from studies of the common architectures and conserved motifs. © 2015 The Protein Society.

  14. Modelling of Mechanical Coupling for Piezoelectric Energy Harvester Adapted to Low-Frequency Vibration

    Science.gov (United States)

    Untoro, T.; Viridi, S.; Suprijanto; Ekawati, E.

    2017-07-01

    In our previous work, we have developed a mechanical coupling for energy harvester from vibration source. This energy harvester uses piezoelectric with additional cantilever beam and permanent magnets. Our work proposed alternative scheme of mechanical coupling for tune the vibration input into resonant frequency of piezoelectric. Based on the experiment, correlation between the length of cantilever beam and the output power also evaluated. In this paper, we try to modelling our work into mathematical model and apply it to some case study. For example application, we apply our energy harvester system to generate electrical energy to enlighten the street. The human footsteps can be used as vibration source to generate electrical energy.

  15. Enhanced processing in arrays of optimally tuned nonlinear biomimetic sensors: A coupling-mediated Ringelmann effect and its dynamical mitigation

    Science.gov (United States)

    Nikitin, Alexander P.; Bulsara, Adi R.; Stocks, Nigel G.

    2017-03-01

    Inspired by recent results on self-tunability in the outer hair cells of the mammalian cochlea, we describe an array of magnetic sensors where each individual sensor can self-tune to an optimal operating regime. The self-tuning gives the array its "biomimetic" features. We show that the overall performance of the array can, as expected, be improved by increasing the number of sensors but, however, coupling between sensors reduces the overall performance even though the individual sensors in the system could see an improvement. We quantify the similarity of this phenomenon to the Ringelmann effect that was formulated 103 years ago to account for productivity losses in human and animal groups. We propose a global feedback scheme that can be used to greatly mitigate the performance degradation that would, normally, stem from the Ringelmann effect.

  16. Mechanical tuning of the moth ear: distortion-product otoacoustic emissions and tympanal vibrations.

    Science.gov (United States)

    Mora, Emanuel C; Cobo-Cuan, Ariadna; Macías-Escrivá, Frank; Pérez, Martha; Nowotny, Manuela; Kössl, Manfred

    2013-10-15

    The mechanical tuning of the ear in the moth Empyreuma pugione was investigated by distortion-product otoacoustic emissions (DPOAE) and laser Doppler vibrometry (LDV). DPOAE audiograms were assessed using a novel protocol that may be advantageous for non-invasive auditory studies in insects. To evoke DPOAE, two-tone stimuli within frequency and level ranges that generated a large matrix of values (960 frequency-level combinations) were used to examine the acoustic space in which the moth tympanum shows its best mechanical and acoustical responses. The DPOAE tuning curve derived from the response matrix resembles that obtained previously by electrophysiology, and is V-shaped and tuned to frequencies between 25 and 45 kHz with low Q10dB values of 1.21±0.26. In addition, while using a comparable stimulation regime, mechanical distortion in the displacement of the moth's tympanal membrane at the stigma was recorded with a laser Doppler vibrometer. The corresponding mechanical vibration audiograms were compared with DPOAE audiograms. Both types of audiograms have comparable shape, but most of the mechanical response fields are shifted towards lower frequencies. We showed for the first time in moths that DPOAE have a pronounced analogy in the vibration of the tympanic membrane where they may originate. Our work supports previous studies that point to the stigma (and the internally associated transduction machinery) as an important place of sound amplification in the moth ear, but also suggests a complex mechanical role for the rest of the transparent zone.

  17. Coupled diffusion and mechanics in battery electrodes

    Science.gov (United States)

    Eshghinejad, Ahmadreza

    We are living in a world with continuous production and consumption of energy. The energy production in the past decades has started to move away from petrochemical sources toward sustainable sources such as solar, wind and geothermal. Also, the energy consumption is further adapting to the sustainable sources. For instance, in recent years electric vehicles are growing fast that can consume sustainable electric energy stored in their batteries. In this direction, in order to further move toward sustainable energy, materials are becoming increasingly important for storing electric energy. Although, currently the technologies such as Li-ion batteries and solid-oxide fuel cells are commercially available for energy applications, improvements are crucial for the next generation of many other technologies producing or consuming sustainable energies. A critical aspect of the electrochemical activities involved in energy storage technologies such as Li-ion batteries and solid-oxide fuel cells is the diffusion of ions into the electrode materials. This process ultimately governs various functional properties of the batteries such as capacity and charging/discharging rates. The first goal of this dissertation is to develop mathematical tools to analyze the ionic diffusion and investigate its coupling with mechanics in electrodes. For this purpose, a thermodynamics-based modeling framework is developed and numerically solved using two numerical methods to analyze ionic diffusion in heterogeneous and structured electrodes. The next goal of this dissertation is to develop and analyze characterization techniques to probe the electrochemical processes at the nano-scale. To this end, the mathematical models are first employed to model a previously developed Atomic Force Microscopy based technique to probe local electrochemical activities called Electrochemical Strain Microscopy (ESM). This method probes the activities by inducing AC electric field to perturb ionic activities and

  18. Mechanical tuning of molecular machines for nucleotide recognition at the air-water interface

    Directory of Open Access Journals (Sweden)

    Shinoda Satoshi

    2011-01-01

    Full Text Available Abstract Molecular machines embedded in a Langmuir monolayer at the air-water interface can be operated by application of lateral pressure. As part of the challenge associated with versatile sensing of biologically important substances, we here demonstrate discrimination of nucleotides by applying a cholesterol-armed-triazacyclononane host molecule. This molecular machine can discriminate ribonucleotides based on a twofold to tenfold difference in binding constants under optimized conditions including accompanying ions in the subphase and lateral surface pressures of its Langmuir monolayer. The concept of mechanical tuning of the host structure for optimization of molecular recognition should become a novel methodology in bio-related nanotechnology as an alternative to traditional strategies based on increasingly complex and inconvenient molecular design strategies.

  19. Modal control of mechanically coupled NEMS arrays for tunable RF filters.

    Science.gov (United States)

    Kharrat, Chady; Colinet, Eric; Duraffourg, Laurent; Hentz, Sebastien; Andreucci, Philippe; Voda, Alina

    2010-06-01

    A novel tuning strategy of nanoelectromechanical systems (NEMS)-based filters is proposed based on the modal control of mechanically coupled NEMS arrays. This is done by adjusting separately addressed distributed actuation and detection configurations proportionally to desired modal vectors. This control scheme enhances the global output signal, raising the power handling of the filter on all channels. Although the modal control of 1-D arrays exhibits narrow-band responses with adjustable resonance frequency, its application to 2-D arrays produces filters with both adjustable bandwidth and central frequency. One possible realization scheme is suggested by using electrostatically driven coupled NEMS arrays whose transduction gains are adjusted by changing the electrodes¿ bias voltages. Dispersion effects on both 1-D array and 2-D array frequency response are analytically expressed using eigenvalues perturbation theory. Based on these results, we show how to reduce their impact by appropriately choosing the coupling stiffness and the number of resonators.

  20. Tuning porosity and radial mechanical properties of DNA origami nanotubes via crossover design

    Science.gov (United States)

    Ma, Zhipeng; Kawai, Kentaro; Hirai, Yoshikazu; Tsuchiya, Toshiyuki; Tabata, Osamu

    2017-06-01

    DNA origami nanotubes are utilized as structural platforms for the fabrication of various micro/nanosystems for drug delivery, optical or biological sensing, and even nanoscale robots. Their radial structural and mechanical properties, which play a crucial role in the effective use of micro/nanosystems, have not been fully studied. In particular, the effects of crossovers, which are basic structures for rationally assembling double-stranded DNA (dsDNA) helices into a nanotube configuration, have not yet been characterized experimentally. To investigate the effects of crossovers on the porosity and the radial mechanical properties of DNA origami nanotubes, we fabricated a DNA origami nanotube with varied crossover designs along the nanotube axis. The radial geometry of the DNA origami nanotube is experimentally characterized by both atomic force microscopy (AFM) and electron cryomicroscopy (cryo-EM). Moreover, the radial mechanical properties of the DNA origami nanotube including the radial modulus are directly measured by force-distance-based AFM. These measurements reveal that the porosity and the radial modulus of DNA origami nanotubes can be tuned by adjusting the crossover design, which enables the optimal design and construction of DNA origami nanostructures for various applications.

  1. Mechanics of couple-stress fluid coatings

    Science.gov (United States)

    Waxman, A. M.

    1982-01-01

    The formal development of a theory of viscoelastic surface fluids with bending resistance - their kinematics, dynamics, and rheology are discussed. It is relevant to the mechanics of fluid drops and jets coated by a thin layer of immiscible fluid with rather general rheology. This approach unifies the hydrodynamics of two-dimensional fluids with the mechanics of an elastic shell in the spirit of a Cosserat continuum. There are three distinct facets to the formulation of surface continuum mechanics. Outlined are the important ideas and results associated with each: the kinematics of evolving surface geometries, the conservation laws governing the mechanics of surface continua, and the rheological equations of state governing the surface stress and moment tensors.

  2. PSO-tuned PID controller for coupled tank system via priority-based fitness scheme

    Science.gov (United States)

    Jaafar, Hazriq Izzuan; Hussien, Sharifah Yuslinda Syed; Selamat, Nur Asmiza; Abidin, Amar Faiz Zainal; Aras, Mohd Shahrieel Mohd; Nasir, Mohamad Na'im Mohd; Bohari, Zul Hasrizal

    2015-05-01

    The industrial applications of Coupled Tank System (CTS) are widely used especially in chemical process industries. The overall process is require liquids to be pumped, stored in the tank and pumped again to another tank. Nevertheless, the level of liquid in tank need to be controlled and flow between two tanks must be regulated. This paper presents development of an optimal PID controller for controlling the desired liquid level of the CTS. Two method of Particle Swarm Optimization (PSO) algorithm will be tested in optimizing the PID controller parameters. These two methods of PSO are standard Particle Swarm Optimization (PSO) and Priority-based Fitness Scheme in Particle Swarm Optimization (PFPSO). Simulation is conducted within Matlab environment to verify the performance of the system in terms of settling time (Ts), steady state error (SSE) and overshoot (OS). It has been demonstrated that implementation of PSO via Priority-based Fitness Scheme (PFPSO) for this system is potential technique to control the desired liquid level and improve the system performances compared with standard PSO.

  3. Coupling functions: Universal insights into dynamical interaction mechanisms

    Science.gov (United States)

    Stankovski, Tomislav; Pereira, Tiago; McClintock, Peter V. E.; Stefanovska, Aneta

    2017-10-01

    The dynamical systems found in nature are rarely isolated. Instead they interact and influence each other. The coupling functions that connect them contain detailed information about the functional mechanisms underlying the interactions and prescribe the physical rule specifying how an interaction occurs. A coherent and comprehensive review is presented encompassing the rapid progress made recently in the analysis, understanding, and applications of coupling functions. The basic concepts and characteristics of coupling functions are presented through demonstrative examples of different domains, revealing the mechanisms and emphasizing their multivariate nature. The theory of coupling functions is discussed through gradually increasing complexity from strong and weak interactions to globally coupled systems and networks. A variety of methods that have been developed for the detection and reconstruction of coupling functions from measured data is described. These methods are based on different statistical techniques for dynamical inference. Stemming from physics, such methods are being applied in diverse areas of science and technology, including chemistry, biology, physiology, neuroscience, social sciences, mechanics, and secure communications. This breadth of application illustrates the universality of coupling functions for studying the interaction mechanisms of coupled dynamical systems.

  4. Mechanism of Torque Production in a Coupled Polyphase ...

    African Journals Online (AJOL)

    This paper studies the nature and mechanism of torque production in a coupled polyphase reluctance machine with two identical stator windings. ... It is shown that the machine develops synchronous torque while operating in the asynchronous mode and the sharing of the load torque between the coupled machine units is ...

  5. Topology Optimization Methods for Acoustic-Mechanical Coupling Problems

    DEFF Research Database (Denmark)

    Jensen, Jakob Søndergaard; Dilgen, Cetin Batur; Dilgen, Sümer Bartug

    2017-01-01

    A comparative overview of methods for topology optimization of acoustic mechanical coupling problems is provided. The goal is to pave the road for developing efficient optimization schemes for the design of complex acoustic devices such as hearingaids.......A comparative overview of methods for topology optimization of acoustic mechanical coupling problems is provided. The goal is to pave the road for developing efficient optimization schemes for the design of complex acoustic devices such as hearingaids....

  6. Mechanical coupling for a rotor shaft assembly of dissimilar materials

    Science.gov (United States)

    Shi, Jun [Glastonbury, CT; Bombara, David [New Hartford, CT; Green, Kevin E [Broad Brook, CT; Bird, Connic [Rocky Hill, CT; Holowczak, John [South Windsor, CT

    2009-05-05

    A mechanical coupling for coupling a ceramic disc member to a metallic shaft includes a first wedge clamp and a second wedge clamp. A fastener engages a threaded end of a tie-bolt to sandwich the ceramic disc between the wedge clamps. An axial spring is positioned between the fastener and the second wedge clamp to apply an axial preload along the longitudinal axis. Another coupling utilizes a rotor shaft end of a metallic rotor shaft as one wedge clamp. Still another coupling includes a solid ceramic rotor disc with a multiple of tie-bolts radially displaced from the longitudinal axis to exert the preload on the solid ceramic rotor disc.

  7. Statistical mechanics of tuned cell signalling: sensitive collective response by synthetic biological circuits

    Science.gov (United States)

    Voliotis, M.; Liverpool, T. B.

    2017-03-01

    Living cells sense and process environmental cues through noisy biochemical mechanisms. This apparatus limits the scope of engineering cells as viable sensors. Here, we highlight a mechanism that enables robust, population-wide responses to external stimulation based on cellular communication, known as quorum sensing. We propose a synthetic circuit consisting of two mutually repressing quorum sensing modules. At low cell densities the system behaves like a genetic toggle switch, while at higher cell densities the behaviour of nearby cells is coupled via diffusible quorum sensing molecules. We show by systematic coarse graining that at large length and timescales that the system can be described using the Ising model of a ferromagnet. Thus, in analogy with magnetic systems, the sensitivity of the population-wide response, or its ‘susceptibility’ to a change in the external signal, is highly enhanced for a narrow range of cell-cell coupling close to a critical value. We expect that our approach will be used to enhance the sensitivity of synthetic bio-sensing networks.

  8. Muscular tissues of the squid Doryteuthis pealeii express identical myosin heavy chain isoforms: an alternative mechanism for tuning contractile speed.

    Science.gov (United States)

    Shaffer, Justin F; Kier, William M

    2012-01-15

    The speed of muscle contraction is largely controlled at the sarcomere level by the ATPase activity of the motor protein myosin. Differences in amino acid sequence in catalytically important regions of myosin yield different myosin isoforms with varying ATPase activities and resulting differences in cross-bridge cycling rates and interfilamentary sliding velocities. Modulation of whole-muscle performance by changes in myosin isoform ATPase activity is regarded as a universal mechanism to tune contractile properties, especially in vertebrate muscles. Invertebrates such as squid, however, may exhibit an alternative mechanism to tune contractile properties that is based on differences in muscle ultrastructure, including variable myofilament and sarcomere lengths. To determine definitively whether contractile properties of squid muscles are regulated via different myosin isoforms (i.e. different ATPase activities), the nucleotide and amino acid sequences of the myosin heavy chain from the squid Doryteuthis pealeii were determined from the mantle, arm, tentacle, fin and funnel retractor musculature. We identified three myosin heavy chain isoforms in squid muscular tissues, with differences arising at surface loop 1 and the carboxy terminus. All three isoforms were detected in all five tissues studied. These results suggest that the muscular tissues of D. pealeii express identical myosin isoforms, and it is likely that differences in muscle ultrastructure, not myosin ATPase activity, represent the most important mechanism for tuning contractile speeds.

  9. Thermo-mechanically coupled deformation with the finite difference method

    Science.gov (United States)

    Duretz, Thibault; Raess, Ludovic; Podladchikov, Yury; Schmalholz, Stefan

    2016-04-01

    Numerous geological observations are the result of thermo-mechanical processes. In particular, tectonic processes such as ductile shear localization can be induced by the intrinsic coupling that exists between deformation, energy and rheology. In order to study these processes, we have designed two-dimensional implicit and explicit finite difference models. These models take into account a temperature-dependent power-law rheology as well as diffusion, advection, and conversion of mechanical work into heat. For implicit models, different non-linear solving strategies were implemented (implicit/explicit thermo-mechanical coupling, Picard/Newton linearisations). We model thermo-mechanically activated shear localization in lower crustal conditions using these different numerical methods. We show that all methods capture the thermo-mechanical instability and exhibit similar temporal evolution. We perform quantitative comparisons with specifically designed tests (conservation of energy, analytical solution, scaling law). For implicit approaches, we discuss the treatment of thermo-mechanical coupling (implicit/explicit) and the impact of the imposed accuracy (tolerance) of the non-linear solvers. We compare the accuracy of the explicit method with the one of the implicit methods. Numerical algorithms based on explicit methods to study thermo-mechanical shear localisation are attractive because they are easy to program and very comprehensible.

  10. Octagonal toroid microcavity for mechanically robust optical coupling

    Directory of Open Access Journals (Sweden)

    Ryo Suzuki

    2015-05-01

    Full Text Available Light is usually coupled to a whispering gallery mode cavity using a tapered fiber. However, it is difficult to stabilize the optical coupling against mechanical vibration because it requires sub-μm control of the gap distance between the fiber and cavity. In this study, we experimentally demonstrate mechanically robust coupling that we realize by allowing the tapered fiber to touch the sidewall of the cavity. By using an octagonal toroid microcavity, we prevent the cavity-waveguide system from over coupling and achieve critical coupling even when the fiber is in contact with the surface of the cavity. We show by numerical analysis that such a deformed microcavity is required if we need to control the coupling, since a circular cavity usually overcouples when the fiber contacts the surface. The fabricated octagonal silica toroid microcavity exhibits a quality factor of 2.2 × 104 when the tapered fiber touches a cavity with a diameter of 80 μm.

  11. Engine Tune-up Service. Unit 2: Charging System. Posttests. Automotive Mechanics Curriculum.

    Science.gov (United States)

    Richardson, Roger L.; Bacon, E. Miles

    This book of posttests is designed to accompany the Engine Tune-Up Service Student Guide for Unit 2, Charging System, available separately as CE 031 208. Focus of the posttest is on the testing of the charging system. One multiple choice posttest is provided, that covers the three performance objectives contained in the unit. (No answer key is…

  12. Engine Tune-Up Service. Unit 3: Primary Circuit. Posttests. Automotive Mechanics Curriculum.

    Science.gov (United States)

    Morse, David T.

    This book of posttests is designed to accompany the Engine Tune-Up Service Student Guide for Unit 3, Primary Circuit, available separately as CE 031 211. Focus of the posttests is setting the primary ignition circuit. One multiple choice posttest is provided, covering the eight performance objectives contained in the unit. (No answer key is…

  13. Engine Tune-Up Service. Unit 1: Battery and Cranking System. Posttests. Automotive Mechanics Curriculum.

    Science.gov (United States)

    Goodson-Roberts, Ludy; And Others

    This book of posttests is designed to accompany the Engine Tune-Up Service Student Guide for Unit 1, Battery and Cranking System. Focus of the posttests is the testing of the battery and cranking system. Four multiple choice posttests are provided, one for each of the performance objectives contained in the unit. (No answer keys are provided.)…

  14. Getting post-M&A integration mechanisms tuned in to technological relatedness and innovation synergy realisation

    NARCIS (Netherlands)

    Wubben, Emiel F.M.; Batterink, Maarten; Omta, Onno

    2016-01-01

    Studies on Mergers and Acquisitions (M&A) typically relate innovation synergies to either context characteristics or post-M&A integration. There is little research on how to tune the relevant practices to the benefit of realising specific innovation synergies. It is the purpose of this

  15. Engine Tune-up Service. Unit 6: Emission Control Systems. Posttests. Automotive Mechanics Curriculum.

    Science.gov (United States)

    Morse, David T.; May, Theodore R.

    This book of posttests is designed to accompany the Engine Tune-Up Service Student Guide for Unit 6, Emission Control Systems, available separately as CE 031 220. Focus of the posttests is inspecting, testing, and servicing emission control systems. One multiple choice posttest is provided that covers the seven performance objectives contained in…

  16. Proton-coupled electron transfer dynamics in the catalytic mechanism of a [NiFe]-hydrogenase.

    Science.gov (United States)

    Greene, Brandon L; Wu, Chang-Hao; McTernan, Patrick M; Adams, Michael W W; Dyer, R Brian

    2015-04-08

    The movement of protons and electrons is common to the synthesis of all chemical fuels such as H2. Hydrogenases, which catalyze the reversible reduction of protons, necessitate transport and reactivity between protons and electrons, but a detailed mechanism has thus far been elusive. Here, we use a phototriggered chemical potential jump method to rapidly initiate the proton reduction activity of a [NiFe] hydrogenase. Coupling the photochemical initiation approach to nanosecond transient infrared and visible absorbance spectroscopy afforded direct observation of interfacial electron transfer and active site chemistry. Tuning of intramolecular proton transport by pH and isotopic substitution revealed distinct concerted and stepwise proton-coupled electron transfer mechanisms in catalysis. The observed heterogeneity in the two sequential proton-associated reduction processes suggests a highly engineered protein environment modulating catalysis and implicates three new reaction intermediates; Nia-I, Nia-D, and Nia-SR(-). The results establish an elementary mechanistic understanding of catalysis in a [NiFe] hydrogenase with implications in enzymatic proton-coupled electron transfer and biomimetic catalyst design.

  17. Fluid coupling in a discrete model of cochlear mechanics.

    Science.gov (United States)

    Elliott, Stephen J; Lineton, Ben; Ni, Guangjian

    2011-09-01

    A discrete model of cochlear mechanics is introduced that includes a full, three-dimensional, description of fluid coupling. This formulation allows the fluid coupling and basilar membrane dynamics to be analyzed separately and then coupled together with a simple piece of linear algebra. The fluid coupling is initially analyzed using a wavenumber formulation and is separated into one component due to one-dimensional fluid coupling and one comprising all the other contributions. Using the theory of acoustic waves in a duct, however, these two components of the pressure can also be associated with a far field, due to the plane wave, and a near field, due to the evanescent, higher order, modes. The near field components are then seen as one of a number of sources of additional longitudinal coupling in the cochlea. The effects of non-uniformity and asymmetry in the fluid chamber areas can also be taken into account, to predict both the pressure difference between the chambers and the mean pressure. This allows the calculation, for example, of the effect of a short cochlear implant on the coupled response of the cochlea. © 2011 Acoustical Society of America

  18. Coupled Thermo-Mechanical and Photo-Chemical Degradation Mechanisms that determine the Reliability and Operational Lifetimes for CPV Technologies

    Energy Technology Data Exchange (ETDEWEB)

    Dauskardt, Reinhold H. [Stanford Univ., CA (United States)

    2017-04-30

    This project sought to identify and characterize the coupled intrinsic photo-chemo-mechanical degradation mechanisms that determine the reliability and operational lifetimes for CPV technologies. Over a three year period, we have completed a highly successful program which has developed quantitative metrologies and detailed physics-based degradation models, providing new insight into the fundamental reliability physics necessary for improving materials, creating accelerated testing protocols, and producing more accurate lifetime predictions. The tasks for the program were separated into two focus areas shown in the figure below. Focus Area 1, led by Reinhold Dauskardt and Warren Cai with a primary collaboration with David Miller of NREL, studied the degradation mechanisms present in encapsulant materials. Focus Area 2, led by Reinhold Dauskardt and Ryan Brock with a primary collaboration with James Ermer and Peter Hebert of Spectrolab, studied stress development and degradation within internal CPV device interfaces. Each focus area was productive, leading to several publications, including findings on the degradation of silicone encapsulant under terrestrial UV, a model for photodegradation of silicone encapsulant adhesion, quantification and process tuning of antireflective layers on CPV, and discovery of a thermal cycling degradation mechanism present in metal gridline structures.

  19. Analysis of the Radiation Mechanisms in and Design of Tightly-Coupled Antenna Arrays

    OpenAIRE

    Vogler, Terry Richard

    2010-01-01

    The objective of this research is to design well-tuned, wideband elements for thin planar or cylindrically conformal arrays of balanced elements fed over ground. These arrays have closely spaced elements to achieve wide bandwidths through mutual coupling. This dissertation develops two wideband designs in infinite, semi-infinite, and finite array configurations. The infinite array is best for element tuning. This research advances a concept of a distributed, parallel capacitance between eleme...

  20. Coherence of mechanical oscillators mediated by coupling to different baths

    Science.gov (United States)

    Boyanovsky, Daniel; Jasnow, David

    2017-07-01

    We study the nonequilibrium dynamics of two mechanical oscillators with general linear couplings to two uncorrelated thermal baths at temperatures T1 and T2, respectively. We obtain the complete solution of the Heisenberg-Langevin equations, which reveal a coherent mixing among the normal modes of the oscillators as a consequence of their off-diagonal couplings to the baths. Unique renormalization aspects resulting from this mixing are discussed. Diagonal and off-diagonal (coherence) correlation functions are obtained analytically in the case of strictly Ohmic baths with different couplings in the strong- and weak-coupling regimes. An asymptotic nonequilibrium stationary state emerges for which we obtain the complete expressions for the correlations and coherence. Remarkably, the coherence survives in the high-temperature, classical limit for T1≠T2 . This is a consequence of the coherence being determined by the difference of the bath correlation functions. In the case of vanishing detuning between the oscillator normal modes both coupling to one and the same bath, the coherence retains memory of the initial conditions at long times. An out-of-equilibrium setup with small detuning and large | T1-T2| produces nonvanishing steady-state coherence in the high-temperature limit of the baths.

  1. Solvothermal tuning of photoluminescent graphene quantum dots: from preparation to photoluminescence mechanism

    Science.gov (United States)

    Qi, Bao-Ping; Zhang, Xiaoru; Shang, Bing-Bing; Xiang, Dongshan; Zhang, Shenghui

    2018-02-01

    Solvothermal synthesis was employed to tune the surface states of graphene quantum dots (GQDs). Two series of GQDs with the particle sizes from 2.6 to 4.5 nm were prepared as follows: (I) GQDs with the same size but different oxygen degrees; (II) GQDs with different core sizes but the similar surface chemistry. Both the large sizes and the high surface oxidation degrees led to the redshift photoluminescence (PL) of GQDs. Electrochemiluminescence (ECL) spectra from two series of GQDs were all in accordance with their PL spectra, respectively, which provided good evidence for the conjugated structures in GQDs responsible for PL. [Figure not available: see fulltext.

  2. The role of Rabi splitting tuning in the dynamics of strongly coupled J-aggregates and surface plasmon polaritons in nanohole arrays.

    Science.gov (United States)

    Wang, Hai; Toma, Andrea; Wang, Hai-Yu; Bozzola, Angelo; Miele, Ermanno; Haddadpour, Ali; Veronis, Georgios; De Angelis, Francesco; Wang, Lei; Chen, Qi-Dai; Xu, Huai-Liang; Sun, Hong-Bo; Zaccaria, Remo Proietti

    2016-07-21

    We have investigated the influence of Rabi splitting tuning on the dynamics of strongly coupled J-aggregate/surface plasmon polariton systems. In particular, the Rabi splitting was tuned by modifying the J-aggregate molecule concentration while a polaritonic system was provided by a nanostructure formed by holes array in a golden layer. From the periodic and concentration changes we have identified, through numerical and experimental steady-state analyses, the best geometrical configuration for maximizing Rabi splitting, which was then used for transient absorption measurements. It was found that in transient absorption spectra, under upper band excitation, two bleaching peaks appear when a nanostructured polaritonic pattern is used. Importantly, their reciprocal distance increases upon increase of J-aggregate concentration, a result confirmed by steady-state analysis. In a similar manner it was also found that the lifetime of the upper band is intimately related to the coupling strength. In particular, we argue that with strong coupling strength, i.e. high J-aggregate concentration, a short lifetime of the upper band has to be expected due to the suppression of the bottleneck effect. This result supports the idea that the dynamics of hybrid systems is profoundly dependent on Rabi splitting.

  3. Coupled Flow and Mechanics in Porous and Fractured Media*

    Science.gov (United States)

    Martinez, M. J.; Newell, P.; Bishop, J.

    2012-12-01

    Numerical models describing subsurface flow through deformable porous materials are important for understanding and enabling energy security and climate security. Some applications of current interest come from such diverse areas as geologic sequestration of anthropogenic CO2, hydro-fracturing for stimulation of hydrocarbon reservoirs, and modeling electrochemistry-induced swelling of fluid-filled porous electrodes. Induced stress fields in any of these applications can lead to structural failure and fracture. The ultimate goal of this research is to model evolving faults and fracture networks and flow within the networks while coupling to flow and mechanics within the intact porous structure. We report here on a new computational capability for coupling of multiphase porous flow with geomechanics including assessment of over-pressure-induced structural damage. The geomechanics is coupled to the flow via the variation in the fluid pore pressures, whereas the flow problem is coupled to mechanics by the concomitant material strains which alter the pore volume (porosity field) and hence the permeability field. For linear elastic solid mechanics a monolithic coupling strategy is utilized. For nonlinear elastic/plastic and fractured media, a segregated coupling is presented. To facilitate coupling with disparate flow and mechanics time scales, the coupling strategy allows for different time steps in the flow solve compared to the mechanics solve. If time steps are synchronized, the controller allows user-specified intra-time-step iterations. The iterative coupling is dynamically controlled based on a norm measuring the degree of variation in the deformed porosity. The model is applied for evaluation of the integrity of jointed caprock systems during CO2 sequestration operations. Creation or reactivation of joints can lead to enhanced pathways for leakage. Similarly, over-pressures can induce flow along faults. Fluid flow rates in fractures are strongly dependent on the

  4. Note: Arbitrary periodical mechanical vibrations can be realized in the resonant state based on multiple tuning fork structure.

    Science.gov (United States)

    He, Liangguo; Pan, Chengliang; Wang, Hongbo; Feng, Zhihua

    2013-09-01

    We develop a novel approach to match harmonics and vibration modes based on the mechanism of multiple tuning fork structure (MTFS), through which it is promising to realize arbitrary periodical vibrations in the resonant state. A prototype three-layer MTFS with first three harmonics is presented to verify the feasibility of the proposed principle. The matching process and experimental results confirm the unique advantages of MTFS, as discussed in the theoretical analysis. Typical periodical motions, including sawtooth, square, half-wave rectified, and full-wave rectified waveforms, are achieved by the syntheses of resonant harmonics.

  5. On localization modes in coupled thermo-hydro-mechanical problems

    Science.gov (United States)

    Benallal, Ahmed

    2005-07-01

    A perturbation approach is used to study localization phenomena in saturated porous media when thermo-mechanical loadings and thermo-hydro-mechanical couplings are fully taken into account. We show that various types of localization modes are possible depending on the constitutive behavior and loading conditions. Examination of the associated conditions in the light of the classical band approach reveals that the differences between these modes lie in their structure which may involve jumps in different variables (beside the velocity gradient) such as the gradients of heat and fluid fluxes, the temperature and the pressure rates. To cite this article: A. Benallal, C. R. Mecanique 333 (2005).

  6. Qubit Coupled Mechanical Resonator in an Electromechanical System

    Science.gov (United States)

    Hao, Yu

    This thesis describes the development of a hybrid quantum electromechanical system. In this system the mechanical resonator is capacitively coupled to a superconducting transmon which is embedded in a superconducting coplanar waveguide (CPW) cavity. The difficulty of achieving high quality of superconducting qubit in a high-quality voltage-biased cavity is overcome by integrating a superconducting reflective T-filter to the cavity. Further spectroscopic and pulsed measurements of the hybrid system demonstrate interactions between the ultra-high frequency mechanical resonator and transmon qubit. The noise of mechanical resonator close to ground state is measured by looking at the spectroscopy of the transmon. At last, fabrication and tests of membrane resonators are discussed.

  7. Electromagnetic coupling of strongly non-local quantum mechanics

    Science.gov (United States)

    Modanese, G.

    2017-11-01

    Although standard quantum mechanics has some non-local features, the probability current of the Schrödinger equation is locally conserved, and this allows minimal electromagnetic coupling. For some important extensions of the Schrödinger equation, however, the probability current is not locally conserved. We show that in these cases the correct electromagnetic coupling requires a relatively simple extension of Maxwell theory which has been known for some time and recently improved by covariant integration of a scalar degree of freedom. We discuss some general properties of the solutions and examine in particular the case of an oscillating dipolar source. Remarkable mathematical and physical differences emerge with respect to Maxwell theory, as a consequence of additional current terms present in the equations for ∇ · E and ∇ × B . Several possible applications are mentioned.

  8. Static and Dynamic Amplification Using Strong Mechanical Coupling

    KAUST Repository

    Ilyas, Saad

    2016-07-28

    Amplifying the signal-to-noise ratio of resonant sensors is vital toward the effort to miniaturize devices into the sub-micro and nano regimes. In this paper, we demonstrate theoretically and experimentally, amplification through mechanically coupled microbeams. The device is composed of two identical clamped-clamped beams, made of polyimide, connected at their middle through a third beam, which acts as a mechanical coupler. Each of the clamped-clamped microbeams and the coupler are designed to be actuated separately, hence providing various possibilities of actuation and sensing. The coupled resonator is driven into resonance near its first resonance mode and its dynamic behavior is explored via frequency sweeps. The results show significant amplification in the resonator amplitude when the signal is measured at the midpoint of the coupler compared with the response of the individual uncoupled beams. The static pull-in characteristics of the resonator are also studied. It is shown that the compliant mechanical coupler can serve as a low-power radio frequency switch actuated at low voltage loads. [2016-0100

  9. Binding, tuning and mechanical function of the 4-hydroxy-cinnamic acid chromophore in photoactive yellow protein

    NARCIS (Netherlands)

    Horst, M.A. van der; Arents, J.C.; Kort, R.; Hellingwerf, K.J.

    2007-01-01

    The bacterial photoreceptor protein photoactive yellow protein (PYP) covalently binds the chromophore 4-hydroxy coumaric acid, tuning (spectral) characteristics of this cofactor. Here, we study this binding and tuning using a combination of pointmutations and chromophore analogs. In all photosensor

  10. Chloroform alters interleaflet coupling in lipid bilayers: an entropic mechanism

    Science.gov (United States)

    Reigada, Ramon; Sagués, Francesc

    2015-01-01

    The interaction of the two leaflets of the plasmatic cell membrane is conjectured to play an important role in many cell processes. Experimental and computational studies have investigated the mechanisms that modulate the interaction between the two membrane leaflets. Here, by means of coarse-grained molecular dynamics simulations, we show that the addition of a small and polar compound such as chloroform alters interleaflet coupling by promoting domain registration. This is interpreted in terms of an entropic gain that would favour frequent chloroform commuting between the two leaflets. The implication of this effect is discussed in relation to the general anaesthetic action. PMID:25833246

  11. Mechanisms of spectral tuning in the RH2 pigments of Tokay gecko and American chameleon

    Science.gov (United States)

    Takenaka, Naomi; Yokoyama, Shozo

    2009-01-01

    At present, molecular bases of spectral tuning in rhodopsin-like (RH2) pigments are not well understood. Here, we have constructed the RH2 pigments of nocturnal Tokay gecko (Gekko gekko) and diurnal American chameleon (Anolis carolinensis) as well as chimeras between them. The RH2 pigments of the gecko and chameleon reconstituted with 11-cis-retinal had the wavelengths of maximal absorption (λmax’s) of 467 and 496 nm, respectively. Chimeric pigment analyses indicated that 76–86%, 14–24%, and 10% of the spectral difference between them could be explained by amino acid differences in transmembrane (TM) helices I~IV, V~VII, and amino acid interactions between the two segments, respectively. Evolutionary and mutagenesis analyses revealed that the λmax’s of the gecko and chameleon pigments diverged from each other not only by S49A (serine to alanine replacement at residue 49), S49F (serine to phenylalanine), L52M (leucine to methionine), D83N (aspartic acid to asparagine), M86T (methionine to thereonine), and T97A (threonine to alanine) but also by other amino acid replacements that cause minor λmax-shifts individually. PMID:17590287

  12. Data mechanics and coupling geometry on binary bipartite networks.

    Directory of Open Access Journals (Sweden)

    Hsieh Fushing

    Full Text Available We quantify the notion of pattern and formalize the process of pattern discovery under the framework of binary bipartite networks. Patterns of particular focus are interrelated global interactions between clusters on its row and column axes. A binary bipartite network is built into a thermodynamic system embracing all up-and-down spin configurations defined by product-permutations on rows and columns. This system is equipped with its ferromagnetic energy ground state under Ising model potential. Such a ground state, also called a macrostate, is postulated to congregate all patterns of interest embedded within the network data in a multiscale fashion. A new computing paradigm for indirect searching for such a macrostate, called Data Mechanics, is devised by iteratively building a surrogate geometric system with a pair of nearly optimal marginal ultrametrics on row and column spaces. The coupling measure minimizing the Gromov-Wasserstein distance of these two marginal geometries is also seen to be in the vicinity of the macrostate. This resultant coupling geometry reveals multiscale block pattern information that characterizes multiple layers of interacting relationships between clusters on row and on column axes. It is the nonparametric information content of a binary bipartite network. This coupling geometry is then demonstrated to shed new light and bring resolution to interaction issues in community ecology and in gene-content-based phylogenetics. Its implied global inferences are expected to have high potential in many scientific areas.

  13. Thermo-hydro-mechanical coupling of largely transformed media

    Science.gov (United States)

    Karrech, A.; Poulet, T.; Regenauer-Lieb, K.

    2011-12-01

    Coupling of multi-physics problems is gaining momentum and attracting the interest of many researchers because of its potential in explaining challenging issues in geothermal industry, mineral deposition processes, waste and gas storage etc. It benefited tremendously from a long history of developments in terms of thermodynamics of systems in equilibrium. Yet, most of the existing literature is limited to infinitesimal transformations of materials (see and references in there). The few models that included finite strain considered classical corotational rates which are known to produce unstable hyperbolic or oscillatory responses especially in shear zones. They also ignored large changes in temperature. The close to equilibrium approaches proved to be viable for engineering design especially in stable porous media, but they are certainly limited in assessing risks and predicting the responses of materials undergoing events of large magnitudes. In this paper, we propose a new formulation which includes logarithmic strain measures and co-rotational rates overcoming the unstable responses in shear zones. It also allows for large temperature variations and includes feedbacks which explicitly track the rate of irreversible entropy production. This fully coupled framework for thermo-hydro-mechanical porous media required the development of a finite element model based on the Galerkin weighting method . The numerical approach includes Newton-Raphson iterative procedures to account for the coupling terms as well as the hyperelasto-plastic response. It also uses the reversible/irreversible split algorithm developed to describe permanent deformation in finite strain.

  14. Mechanism of electromechanical coupling in voltage-gated potassium channels

    Directory of Open Access Journals (Sweden)

    Rikard eBlunck

    2012-09-01

    Full Text Available Voltage-gated ion channels play a central role in the generation of action potentials in the nervous system. They are selective for one type of ion – sodium, calcium or potassium. Voltage-gated ion channels are composed of a central pore that allows ions to pass through the membrane and four peripheral voltage sensing domains that respond to changes in the membrane potential. Upon depolarization, voltage sensors in voltage-gated potassium channels (Kv undergo conformational changes driven by positive charges in the S4 segment and aided by pairwise electrostatic interactions with the surrounding voltage sensor. Structure-function relations of Kv channels have been investigated in detail, and the resulting models on the movement of the voltage sensors now converge to a consensus; the S4 segment undergoes a combined movement of rotation, tilt and vertical displacement in order to bring 3-4 e+ each through the electric field focused in this region. Nevertheless, the mechanism by which the voltage sensor movement leads to pore opening, the electromechanical coupling, is still not fully understood. Thus, recently, electromechanical coupling in different Kv channels has been investigated with a multitude of techniques including electrophysiology, 3D crystal structures, fluorescence spectroscopy and molecular dynamics simulations. Evidently, the S4-S5 linker, the covalent link between the voltage sensor and pore, plays a crucial role. The linker transfers the energy from the voltage sensor movement to the pore domain via an interaction with the S6 C-termini, which are pulled open during gating. In addition, other contact regions have been proposed. This review aims to provide (i an in-depth comparison of the molecular mechanisms of electromechanical coupling in different Kv channels; (ii insight as to how the voltage sensor and pore domain influence one another; and (iii theoretical predictions on the movement of the cytosolic face of the KV channels

  15. Failure mechanisms and electromechanical coupling in semiconducting nanowires

    Directory of Open Access Journals (Sweden)

    Peng B.

    2010-06-01

    Full Text Available One dimensional nanostructures, like nanowires and nanotubes, are increasingly being researched for the development of next generation devices like logic gates, transistors, and solar cells. In particular, semiconducting nanowires with a nonsymmetric wurtzitic crystal structure, such as zinc oxide (ZnO and gallium nitride (GaN, have drawn immense research interests due to their electromechanical coupling. The designing of the future nanowire-based devices requires component-level characterization of individual nanowires. In this paper, we present a unique experimental set-up to characterize the mechanical and electromechanical behaviour of individual nanowires. Using this set-up and complementary atomistic simulations, mechanical properties of ZnO nanowires and electromechanical properties of GaN nanowires were investigated. In ZnO nanowires, elastic modulus was found to depend on nanowire diameter decreasing from 190 GPa to 140 GPa as the wire diameter increased from 5 nm to 80 nm. Inconsistent failure mechanisms were observed in ZnO nanowires. Experiments revealed a brittle fracture, whereas simulations using a pairwise potential predicted a phase transformation prior to failure. This inconsistency is addressed in detail from an experimental as well as computational perspective. Lastly, in addition to mechanical properties, preliminary results on the electromechanical properties of gallium nitride nanowires are also reported. Initial investigations reveal that the piezoresistive and piezoelectric behaviour of nanowires is different from bulk gallium nitride.

  16. A new hybrid piezo-actuated compliant mechanism with self-tuned flexure arm

    Science.gov (United States)

    Ling, Mingxiang; Cao, Junyi

    2017-04-01

    Recent interests and demands for developing video-rate atomic force microscopes, high-throughput probe-based nanofabrication and high-frequency vibration generator for assisted-machining are increasingly posing new challenges for designing high-bandwidth and large-range piezo-actuated compliant mechanisms. The previous studies mainly focused on making the trade-off between natural frequency and motion range by designing a proper topology. Differing from the previous works, this paper attempts to break the deadlock by employing both piezo-stacks and piezoelectric patches to actuate compliant mechanisms. In this method, piezo-stacks provide an actuating force similar to the traditional way, while piezoelectric patches are bonded on the surface of the flexure arms in compliant mechanisms. These `active' laminaes are used to further actuate the hosting flexural beam by inducing strains on the interface and then give additional bending moments to the flexural arms, which enlarge the output displacement of the compliant mechanism while without the sacrifice of natural frequency. An analytical formulation is established to illustrate the new driving principle and the compound static behaviour of a specific hybrid piezo-actuated multistage compliant mechanism. Initial prototype is also manufactured and experimentally testing is conducted to verify the feasibility of the method.

  17. Optical and mechanical mode tuning in an optomechanical crystal with light-induced thermal effects

    CERN Document Server

    Navarro-Urrios, D; Capuj, N E; Alzina, F; Griol, A; Puerto, D; Martínez, A; Sotomayor-Torres, C M

    2016-01-01

    We report on the modification of the optical and mechanical properties of a silicon 1D optomechanical crystal cavity due to thermo-optic effects in a high phonon/photon population regime. The cavity heats up due to light absorption in a way that shifts the optical modes towards longer wavelengths and the mechanical modes to lower frequencies. By combining the experimental optical results with finite-difference time-domain simulations we establish a direct relation between the observed wavelength drift and the actual effective temperature increase of the cavity. By assuming that the Young's modulus decreases accordingly to the temperature increase, we find a good agreement between the mechanical mode drift predicted using a finite element method and the experimental one.

  18. Defect-related internal dissipation in mechanical resonators and the study of coupled mechanical systems.

    Energy Technology Data Exchange (ETDEWEB)

    Friedmann, Thomas Aquinas; Czaplewski, David A.; Sullivan, John Patrick; Modine, Normand Arthur; Wendt, Joel Robert; Aslam, Dean (Michigan State University, Lansing, MI); Sepulveda-Alancastro, Nelson (University of Puerto Rico, Mayaguez, PR)

    2007-01-01

    Understanding internal dissipation in resonant mechanical systems at the micro- and nanoscale is of great technological and fundamental interest. Resonant mechanical systems are central to many sensor technologies, and microscale resonators form the basis of a variety of scanning probe microscopies. Furthermore, coupled resonant mechanical systems are of great utility for the study of complex dynamics in systems ranging from biology to electronics to photonics. In this work, we report the detailed experimental study of internal dissipation in micro- and nanomechanical oscillators fabricated from amorphous and crystalline diamond materials, atomistic modeling of dissipation in amorphous, defect-free, and defect-containing crystalline silicon, and experimental work on the properties of one-dimensional and two-dimensional coupled mechanical oscillator arrays. We have identified that internal dissipation in most micro- and nanoscale oscillators is limited by defect relaxation processes, with large differences in the nature of the defects as the local order of the material ranges from amorphous to crystalline. Atomistic simulations also showed a dominant role of defect relaxation processes in controlling internal dissipation. Our studies of one-dimensional and two-dimensional coupled oscillator arrays revealed that it is possible to create mechanical systems that should be ideal for the study of non-linear dynamics and localization.

  19. Polyvinyl chloride as a multimodal tissue-mimicking material with tuned mechanical and medical imaging properties.

    Science.gov (United States)

    Li, Weisi; Belmont, Barry; Greve, Joan M; Manders, Adam B; Downey, Brian C; Zhang, Xi; Xu, Zhen; Guo, Dongming; Shih, Albert

    2016-10-01

    The mechanical and imaging properties of polyvinyl chloride (PVC) can be adjusted to meet the needs of researchers as a tissue-mimicking material. For instance, the hardness can be adjusted by changing the ratio of softener to PVC polymer, mineral oil can be added for lubrication in needle insertion, and glass beads can be added to scatter acoustic energy similar to biological tissue. Through this research, the authors sought to develop a regression model to design formulations of PVC with targeted mechanical and multimodal medical imaging properties. The design of experiment was conducted by varying three factors-(1) the ratio of softener to PVC polymer, (2) the mass fraction of mineral oil, and (3) the mass fraction of glass beads-and measuring the mechanical properties (elastic modulus, hardness, viscoelastic relaxation time constant, and needle insertion friction force) and the medical imaging properties [speed of sound, acoustic attenuation coefficient, magnetic resonance imaging time constants T1 and T2, and the transmittance of the visible light at wavelengths of 695 nm (Tλ695) and 532 nm (Tλ532)] on twelve soft PVC samples. A regression model was built to describe the relationship between the mechanical and medical imaging properties and the values of the three composition factors of PVC. The model was validated by testing the properties of a PVC sample with a formulation distinct from the twelve samples. The tested soft PVC had elastic moduli from 6 to 45 kPa, hardnesses from 5 to 50 Shore OOO-S, viscoelastic stress relaxation time constants from 114.1 to 191.9 s, friction forces of 18 gauge needle insertion from 0.005 to 0.086 N/mm, speeds of sound from 1393 to 1407 m/s, acoustic attenuation coefficients from 0.38 to 0.61 (dB/cm)/MHz, T1 relaxation times from 426.3 to 450.2 ms, T2 relaxation times from 21.5 to 28.4 ms, Tλ695 from 46.8% to 92.6%, and Tλ532 from 41.1% to 86.3%. Statistically significant factors of each property were identified. The

  20. Tuning mechanical performance of poly(ethylene glycol) and agarose interpenetrating network hydrogels for cartilage tissue engineering.

    Science.gov (United States)

    Rennerfeldt, Deena A; Renth, Amanda N; Talata, Zsolt; Gehrke, Stevin H; Detamore, Michael S

    2013-11-01

    Hydrogels are attractive for tissue engineering applications due to their incredible versatility, but they can be limited in cartilage tissue engineering applications due to inadequate mechanical performance. In an effort to address this limitation, our team previously reported the drastic improvement in the mechanical performance of interpenetrating networks (IPNs) of poly(ethylene glycol) diacrylate (PEG-DA) and agarose relative to pure PEG-DA and agarose networks. The goal of the current study was specifically to determine the relative importance of PEG-DA concentration, agarose concentration, and PEG-DA molecular weight in controlling mechanical performance, swelling characteristics, and network parameters. IPNs consistently had compressive and shear moduli greater than the additive sum of either single network when compared to pure PEG-DA gels with a similar PEG-DA content. IPNs withstood a maximum stress of up to 4.0 MPa in unconfined compression, with increased PEG-DA molecular weight being the greatest contributing factor to improved failure properties. However, aside from failure properties, PEG-DA concentration was the most influential factor for the large majority of properties. Increasing the agarose and PEG-DA concentrations as well as the PEG-DA molecular weight of agarose/PEG-DA IPNs and pure PEG-DA gels improved moduli and maximum stresses by as much as an order of magnitude or greater compared to pure PEG-DA gels in our previous studies. Although the viability of encapsulated chondrocytes was not significantly affected by IPN formulation, glycosaminoglycan (GAG) content was significantly influenced, with a 12-fold increase over a three-week period in gels with a lower PEG-DA concentration. These results suggest that mechanical performance of IPNs may be tuned with partial but not complete independence from biological performance of encapsulated cells. © 2013 Elsevier Ltd. All rights reserved.

  1. Finite element procedures for coupled linear analysis of heat transfer, fluid and solid mechanics

    Science.gov (United States)

    Sutjahjo, Edhi; Chamis, Christos C.

    1993-01-01

    Coupled finite element formulations for fluid mechanics, heat transfer, and solid mechanics are derived from the conservation laws for energy, mass, and momentum. To model the physics of interactions among the participating disciplines, the linearized equations are coupled by combining domain and boundary coupling procedures. Iterative numerical solution strategy is presented to solve the equations, with the partitioning of temporal discretization implemented.

  2. Tuning reactivity and mechanism in oxidation reactions by mononuclear nonheme iron(IV)-oxo complexes.

    Science.gov (United States)

    Nam, Wonwoo; Lee, Yong-Min; Fukuzumi, Shunichi

    2014-04-15

    Mononuclear nonheme iron enzymes generate high-valent iron(IV)-oxo intermediates that effect metabolically important oxidative transformations in the catalytic cycle of dioxygen activation. In 2003, researchers first spectroscopically characterized a mononuclear nonheme iron(IV)-oxo intermediate in the reaction of taurine: α-ketogultarate dioxygenase (TauD). This nonheme iron enzyme with an iron active center was coordinated to a 2-His-1- carboxylate facial triad motif. In the same year, researchers obtained the first crystal structure of a mononuclear nonheme iron(IV)-oxo complex bearing a macrocyclic supporting ligand, [(TMC)Fe(IV)(O)](2+) (TMC = 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecene), in studies that mimicked the biological enzymes. With these breakthrough results, many other studies have examined mononuclear nonheme iron(IV)-oxo intermediates trapped in enzymatic reactions or synthesized in biomimetic reactions. Over the past decade, researchers in the fields of biological, bioinorganic, and oxidation chemistry have extensively investigated the structure, spectroscopy, and reactivity of nonheme iron(IV)-oxo species, leading to a wealth of information from these enzymatic and biomimetic studies. This Account summarizes the reactivity and mechanisms of synthetic mononuclear nonheme iron(IV)-oxo complexes in oxidation reactions and examines factors that modulate their reactivities and change their reaction mechanisms. We focus on several reactions including the oxidation of organic and inorganic compounds, electron transfer, and oxygen atom exchange with water by synthetic mononuclear nonheme iron(IV)-oxo complexes. In addition, we recently observed that the C-H bond activation by nonheme iron(IV)-oxo and other nonheme metal(IV)-oxo complexes does not follow the H-atom abstraction/oxygen-rebound mechanism, which has been well-established in heme systems. The structural and electronic effects of supporting ligands on the oxidizing power of iron

  3. Tuning of redox regulatory mechanisms, reactive oxygen species and redox homeostasis under salinity stress

    Directory of Open Access Journals (Sweden)

    Hossain eSazzad

    2016-05-01

    Full Text Available Soil salinity is a crucial environmental constraint which limits biomass production at many sites on a global scale. Saline growth conditions cause osmotic and ionic imbalances, oxidative stress and perturb metabolism, e.g. the photosynthetic electron flow. The plant ability to tolerate salinity is determined by multiple biochemical and physiological mechanisms protecting cell functions, in particular by regulating proper water relations and maintaining ion homeostasis. Redox homeostasis is a fundamental cell property. Its regulation includes control of reactive oxygen species (ROS generation, sensing deviation from and readjustment of the cellular redox state. All these redox related functions have been recognized as decisive factors in salinity acclimation and adaptation. This review focuses on the core response of plants to overcome the challenges of salinity stress through regulation of ROS generation and detoxification systems and to maintain redox homeostasis. Emphasis is given to the role of NADH oxidase (RBOH, alternative oxidase (AOX, the plastid terminal oxidase (PTOX and the malate valve with the malate dehydrogenase isoforms under salt stress. Overwhelming evidence assigns an essential auxiliary function of ROS and redox homeostasis to salinity acclimation of plants.

  4. Laboratory simulation of rockslide creep and hydro-mechanical coupling

    Science.gov (United States)

    Agliardi, Federico; Scuderi, Marco M.; Collettini, Cristiano

    2017-04-01

    Deep-seated rockslides are major threats in mountain areas, evolving over hundreds or thousands of years in changing morpho-climatic settings. They usually exhibit time-dependent displacements with superposed long-term and seasonal creep components, the latter related to hydrologic forcing (e.g. rainfall and snowmelt). Most rockslide deformation usually localizes in one or more shear zones, especially in crystalline anisotropic rocks. Shear zones are made of cataclastic breccia and gouge layers similar to those occurring in tectonic faults zones. While several mathematical models have been proposed to reproduce observed rockslide behaviour, only a few laboratory investigations, mostly limited to the assessment of residual friction properties, have been carried out. Here we present laboratory experiments to characterize the frictional stability and time-dependent slip behaviour of real rockslide shear zones, using a biaxial apparatus within a pressure vessel (BRAVA). In order to compare experimental results with in situ observations, we characterized samples collected by full-core boreholes at a depth of 90m from the shear zones of the 50 Mm3 Spriana rockslide (Central Alps, Italy). The rockslide is characterised by long-term evolution after the Last Glacial Maximum, over a century of documented activity and over 25 years of deformation and hydrological monitoring. The rockslide creeps at slow rates of 0.4-3 cm/yr and undergoes order-of-magnitude acceleration stages correlated with groundwater fluctuations. We performed the experiments on 5x5cm samples of phyllosilicate-rich gouge under stress conditions characteristic of the sampled shear zones. We designed experiments in order to evaluate: 1) shear zone strength and permeability; 2) rate- and state- frictional properties for shear displacement rates (0.1-500 microns/s) covering the range of real rockslide slow-to-fast transition; 3) shear zone creep and hydro-mechanical coupling behaviour in response to pore

  5. Tuning acoustic and mechanical properties of materials for ultrasound phantoms and smart substrates for cell cultures.

    Science.gov (United States)

    Cafarelli, A; Verbeni, A; Poliziani, A; Dario, P; Menciassi, A; Ricotti, L

    2017-02-01

    Materials with tailored acoustic properties are of great interest for both the development of tissue-mimicking phantoms for ultrasound tests and smart scaffolds for ultrasound mediated tissue engineering and regenerative medicine. In this study, we assessed the acoustic properties (speed of sound, acoustic impedance and attenuation coefficient) of three different materials (agarose, polyacrylamide and polydimethylsiloxane) at different concentrations or cross-linking levels and doped with different concentrations of barium titanate ceramic nanoparticles. The selected materials, besides different mechanical features (stiffness from few kPa to 1.6MPa), showed a wide range of acoustic properties (speed of sound from 1022 to 1555m/s, acoustic impedance from 1.02 to 1.67MRayl and attenuation coefficient from 0.2 to 36.5dB/cm), corresponding to ranges in which natural soft tissues can fall. We demonstrated that this knowledge can be used to build tissue-mimicking phantoms for ultrasound-based medical procedures and that the mentioned measurements enable to stimulate cells with a highly controlled ultrasound dose, taking into account the attenuation due to the cell-supporting scaffold. Finally, we were able to correlate for the first time the bioeffect on human fibroblasts, triggered by piezoelectric barium titanate nanoparticles activated by low-intensity pulsed ultrasound, with a precise ultrasound dose delivered. These results may open new avenues for the development of both tissue-mimicking materials for ultrasound phantoms and smart triggerable scaffolds for tissue engineering and regenerative medicine. This study reports for the first time the results of a systematic acoustic characterization of agarose, polyacrylamide and polydimethylsiloxane at different concentrations and cross-linking extents and doped with different concentrations of barium titanate nanoparticles. These results can be used to build tissue-mimicking phantoms, useful for many ultrasound

  6. Mode coupling mechanisms in liquids studied by 2D Raman scattering

    NARCIS (Netherlands)

    Steffen, T; Duppen, K.; Elsaesser, T; Fujimoto, JG; Wiersma, DA; Zinth, W

    1998-01-01

    Femtosecond temporally two-dimensional Raman scattering, that was originally designed to characterize the time scale(s) of intermolecular dynamics in liquids, also provides information on mode coupling mechanisms. Polarizability mode coupling suppresses the formation of motional echoes, that

  7. A coupled thermo-mechanical model of friction stir welding

    Directory of Open Access Journals (Sweden)

    Veljić Darko M.

    2012-01-01

    Full Text Available A coupled thermo-mechanical model was developed to study the temperature fields, the plunge force and the plastic deformations of Al alloy 2024-T351 under different rotating speed: 350, 400 and 450 rpm, during the friction stir welding (FSW process. Three-dimensional FE model has been developed in ABAQUS/Explicit using the arbitrary Lagrangian-Eulerian formulation, the Johnson-Cook material law and the Coulomb’s Law of friction. Numerical results indicate that the maximum temperature in the FSW process is lower than the melting point of the welding material. The temperature filed is approximately symmetrical along the welding line. A lower plastic strain region can be found near the welding tool in the trailing side on the bottom surface. With increasing rotation speed, the low plastic strain region is reduced. When the rotational speed is increased, the plunge force can be reduced. Regions with high equivalent plastic strains are observed which correspond to the nugget and the flow arm.

  8. Research on anti crack mechanism of bionic coupling brake disc

    Science.gov (United States)

    Shi, Lifeng; Yang, Xiao; Zheng, Lingnan; Wu, Can; Ni, Jing

    2017-09-01

    According to the biological function of fatigue resistance possessed by biology, this study designed a Bionic Coupling Brake Disc (BCBD) which can inhibit crack propagation as the result of improving fatigue property. Thermal stress field of brake disc was calculated under emergency working condition, and circumferential and radial stress field which lead to fatigue failure of brake disc were investigated simultaneously. Results showed that the maximum temperature of surface reached 890°C and the maximum residual tensile stress was 207 Mpa when the initial velocity of vehicle was 200 km/h. Based on the theory of elastic plastic fracture mechanics, the crack opening displacement and the crack front J integrals of the BCBD and traditional brake disc (TBD) with pre-cracking were calculated, and the strength of crack front was compared. Results revealed the growth behavior of fatigue crack located on surface of brake disc, and proved the anti fatigue resistance of BCBD was better, and the strength of crack resistance of BCBD was much stronger than that of TBD. This simulation research provided significant references for optimization and manufacturing of BCBD.

  9. Electro-mechanical coupling of rotating 3D beams

    Directory of Open Access Journals (Sweden)

    Stoykov S.

    2016-01-01

    Full Text Available A rotating thin-walled beam with piezoelectric element is analysed. The beam is considered to vibrate in space, hence the longitudinal, transverse and torsional deformations are taken into account. The bending deformations of the beam are modelled by assuming Timoshenko's theory. Torsion is included by considering that the cross section rotates as a rigid body but can deform in longitudinal direction due to warping. The warping function is computed preliminary by the finite element method. The equation of motion is derived by the principle of virtual work and discretized in space by the Ritz method. Electro-mechanical coupling is included in the model by considering the internal electrical energy and the electric charge output. The piezo-electric constitutive relations are used in reduced form. The beam is assumed to rotate about a fixed axis with constant speed. The equation of motion is derived in rotating coordinate system, but the influence of the rotation of the coordinate system is taken into account through the inertia forces. Results in time domain are presented for different speeds of rotation and frequencies of vibration. The influence of the speed of rotation and of the frequency of vibration on the electrical output is presented and analysed.

  10. Hydro-chemo-mechanical coupling in sediments: Localized mineral dissolution

    KAUST Repository

    Cha, Minsu

    2016-06-11

    Mineral dissolution is inherently a chemo-hydro-mechanical coupled process. Field evidence and laboratory results show that dissolution may localize and form open conduits in cohesive media such as carbonate rocks. This study focuses on the evolution of localized dissolution in soils (i.e., frictional and non-cohesive granular materials) under effective confining stresses. Experimental results show the development of localized dissolution (“pipe”) when a carbonate-quartz sand is subjected to reactive fluid flow: only loosely packed quartz grains remain within pipes, and the number of pipes decreases away from the inlet port. Concurrent shear wave velocity measurements show a decrease in stiffness during dissolution due to stress and fabric changes, and more complex signal codas anticipate the development of internal heterogeneity. The discrete element method is used to simulate localized vertical dissolution features in granular materials, under constant vertical stress and zero lateral strain far-field boundaries. As porosity increases along dissolution pipes, vertical load is transferred to the surrounding soils and marked force chains develop. In terms of equivalent stress, principal stress rotation takes place within pipes and the sediment reaches the Coulomb failure condition inside pipes and in the surrounding medium. Dissolution pipes alter the geo-plumbing of the subsurface, enhance fluid transport but limit the long term performance of storage systems, alter the fluid pressure and effective stress fields, soften the sediment and may trigger shear failures.

  11. Optimum Tuning of a Gyroscopic Vibration Absorber Using Coupled Gyroscopes for Vibration Control of a Vertical Cantilever Beam

    Directory of Open Access Journals (Sweden)

    F. Ünker

    2016-01-01

    Full Text Available This paper deals with the investigation of optimum values of the stiffness and damping which connect two gyroscopic systems formed by two rotors mounted in gimbal assuming negligible masses for the spring, damper, and gimbal support. These coupled gyroscopes use two gyroscopic flywheels, spinning in opposing directions to have reverse precessions to eliminate the forces due to the torque existing in the torsional spring and the damper between gyroscopes. The system is mounted on a vertical cantilever with the purpose of studying the horizontal and vertical vibrations. The equation of motion of the compound system (gyro-beam system is introduced and solved to find the response measured on the primary system. This is fundamental to design, in some way, the dynamic absorber or neutralizer. On the other hand, the effect of the angular velocities of the gyroscopes are studied, and it is shown that the angular velocity (spin velocity of a gyroscope has a significant effect on the behavior of the dynamic motion. Correctness of the analytical results is verified by numerical simulations. The comparison with the results from the derivation of the corresponding frequency equations shows that the optimized stiffness and damping values are very accurate.

  12. Tuning the ITO work function by capacitively coupled plasma and its application in inverted organic solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Ming [Laboratory of Plasma Physics and Materials, Beijing Institute of Graphic Communication, Beijing (China); Zhang, Chunmei, E-mail: zhangchunmei@bigc.edu.cn [Laboratory of Plasma Physics and Materials, Beijing Institute of Graphic Communication, Beijing (China); Chen, Qiang [Laboratory of Plasma Physics and Materials, Beijing Institute of Graphic Communication, Beijing (China); State Key Laboratory of Electrical Insulation and Power Equipment, Xi’an Jiaotong University, Xi’an (China)

    2016-11-01

    Highlights: • The work function of ITO was reduced by plasma treatment. • The reduction of the work function was attributed to the variation in chemical component of ITO surface. • The inverted solar cell without electron transport layer was fabricated using plasma-treated ITO. • Optimal power conversion efficiency of 3.22% was achieved. - Abstract: In this paper, we investigated the performance of inverted organic solar cells (OSCs) with plasma-treated indium tin oxide (ITO) as the cathode for omitting an electron transport layer. The Ar plasma was produced by capcitively coupled plasma setup under 20 Pa chamber pressure. For the device with the structure of plasma-treated ITO/P3HT:PCBM/MoO{sub 3}/Ag, a power conversion efficiency (PCE) of 3.22% was achieved, whereas PCE of 1.13% was recorded from the device fabricated with the pristine ITO. The photovoltaic performance was found to be dependent on the applied power of plasma. After analyzing by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS), we concluded that the chemical component variation of ITOs surface resulted in the decrease of ITO work function, which meant that the ITO Fermi level became shallow relative to the vacuum level. The low work function of ITO should be responsible for the improvement of inverted OSCs because of the better energy level alignment between ITO and the photoactive layer.

  13. Tuning extreme ultraviolet emission for optimum coupling with multilayer mirrors for future lithography through control of ionic charge states

    Energy Technology Data Exchange (ETDEWEB)

    Ohashi, Hayato, E-mail: ohashi@cc.utsunomiya-u.ac.jp; Higashiguchi, Takeshi, E-mail: higashi@cc.utsunomiya-u.ac.jp; Suzuki, Yuhei; Kawasaki, Masato [Department of Advanced Interdisciplinary Sciences, Center for Optical Research and Education (CORE), Utsunomiya University, Yoto 7-1-2, Utsunomiya, Tochigi 321-8585 (Japan); Li, Bowen; Dunne, Padraig; O' Sullivan, Gerry [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland); Kanehara, Tatsuhiko; Aida, Yuya; Nakamura, Nobuyuki [Institute for Laser Science, The University of Electro-Communications, Chofu, Tokyo 182-8585 (Japan); Torii, Shuichi; Makimura, Tetsuya [Institute of Applied Physics, University of Tsukuba, Tsukuba, Ibaraki 305-8573 (Japan); Jiang, Weihua [Department of Electrical Engineering, Nagaoka University of Technology, Kami-tomiokamachi 1603-1, Nagaoka, Niigata 940-2188 (Japan)

    2014-01-21

    We report on the identification of the optimum plasma conditions for a laser-produced plasma source for efficient coupling with multilayer mirrors at 6.x nm for beyond extreme ultraviolet lithography. A small shift to lower energies of the peak emission for Nd:YAG laser-produced gadolinium plasmas was observed with increasing laser power density. Charge-defined emission spectra were observed in electron beam ion trap (EBIT) studies and the charge states responsible identified by use of the flexible atomic code (FAC). The EBIT spectra displayed a larger systematic shift of the peak wavelength of intense emission at 6.x nm to longer wavelengths with increasing ionic charge. This combination of spectra enabled the key ion stage to be confirmed as Gd{sup 18+}, over a range of laser power densities, with contributions from Gd{sup 17+} and Gd{sup 19+} responsible for the slight shift to longer wavelengths in the laser-plasma spectra. The FAC calculation also identified the origin of observed out-of-band emission and the charge states responsible.

  14. Tuning the structural coupling between the transmembrane and cytoplasmic domains of phospholamban to control sarcoplasmic reticulum Ca(2+)-ATPase (SERCA) function.

    Science.gov (United States)

    Ha, Kim N; Gustavsson, Martin; Veglia, Gianluigi

    2012-12-01

    Phospholamban (PLN) is the endogenous inhibitor of the sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA), the integral membrane enzyme responsible for 70 % of the removal of Ca(2+) from the cytosol, inducing cardiac muscle relaxation in humans. Dysfunctions in SERCA:PLN interactions have been implicated as having a critical role in cardiac disease, and targeting Ca(2+) transport has been demonstrated to be a promising avenue in treating conditions of heart failure. Here, we designed a series of new mutants able to tune SERCA function, targeting the loop sequence that connects the transmembrane and cytoplasmic helices of PLN. We found that a variable degree of loss of inhibition mutants is attainable by engineering glycine mutations along PLN's loop domain. Remarkably, a double glycine mutation results in a complete loss-of-function mutant, fully mimicking the phosphorylated state of PLN. Using nuclear magnetic resonance spectroscopy, we rationalized the effects of these mutations in terms of entropic control on PLN function, whose inhibitory function can be modulated by increasing its conformational dynamics. However, if PLN mutations go past a threshold set by the phosphorylated state, they break the structural coupling between the transmembrane and cytoplasmic domains, resulting in a species that behaves as the inhibitory transmembrane domain alone. These studies provide new potential candidates for gene therapy to reverse the effects of heart failure.

  15. A Transcriptional Regulatory Mechanism Finely Tunes the Firing of Type VI Secretion System in Response to Bacterial Enemies

    Science.gov (United States)

    Lazzaro, Martina; Feldman, Mario F.

    2017-01-01

    ABSTRACT The ability to detect and measure danger from an environmental signal is paramount for bacteria to respond accordingly, deploying strategies that halt or counteract potential cellular injury and maximize survival chances. Type VI secretion systems (T6SSs) are complex bacterial contractile nanomachines able to target toxic effectors into neighboring bacteria competing for the same colonization niche. Previous studies support the concept that either T6SSs are constitutively active or they fire effectors in response to various stimuli, such as high bacterial density, cell-cell contact, nutrient depletion, or components from dead sibling cells. For Serratia marcescens, it has been proposed that its T6SS is stochastically expressed, with no distinction between harmless or aggressive competitors. In contrast, we demonstrate that the Rcs regulatory system is responsible for finely tuning Serratia T6SS expression levels, behaving as a transcriptional rheostat. When confronted with harmless bacteria, basal T6SS expression levels suffice for Serratia to eliminate the competitor. A moderate T6SS upregulation is triggered when, according to the aggressor-prey ratio, an unbalanced interplay between homologous and heterologous effectors and immunity proteins takes place. Higher T6SS expression levels are achieved when Serratia is challenged by a contender like Acinetobacter, which indiscriminately fires heterologous effectors able to exert lethal cellular harm, threatening the survival of the Serratia population. We also demonstrate that Serratia’s RcsB-dependent T6SS regulatory mechanism responds not to general stress signals but to the action of specific effectors from competitors, displaying an exquisite strategy to weigh risks and keep the balance between energy expenditure and fitness costs. PMID:28830939

  16. Coupled Mechanical-Electrochemical-Thermal Analysis of Failure Propagation in Lithium-ion Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Chao; Santhanagopalan, Shriram; Pesaran, Ahmad

    2016-07-28

    This is a presentation given at the 12th World Congress for Computational Mechanics on coupled mechanical-electrochemical-thermal analysis of failure propagation in lithium-ion batteries for electric vehicles.

  17. Calibration of quartz tuning fork spring constants for non-contact atomic force microscopy: direct mechanical measurements and simulations

    Science.gov (United States)

    Langewisch, Gernot; Schurig, Philipp; Hölscher, Hendrik; Fuchs, Harald; Schirmeisen, André

    2014-01-01

    Summary Quartz tuning forks are being increasingly employed as sensors in non-contact atomic force microscopy especially in the “qPlus” design. In this study a new and easily applicable setup has been used to determine the static spring constant at several positions along the prong of the tuning fork. The results show a significant deviation from values calculated with the beam formula. In order to understand this discrepancy the complete sensor set-up has been digitally rebuilt and analyzed by using finite element method simulations. These simulations provide a detailed view of the strain/stress distribution inside the tuning fork. The simulations show quantitative agreement with the beam formula if the beam origin is shifted to the position of zero stress onset inside the tuning fork base and torsional effects are also included. We further found significant discrepancies between experimental calibration values and predictions from the shifted beam formula, which are related to a large variance in tip misalignment during the tuning fork assembling process. PMID:24778977

  18. 49 CFR 238.207 - Link between coupling mechanism and car body.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Link between coupling mechanism and car body. 238.207 Section 238.207 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL... Requirements for Tier I Passenger Equipment § 238.207 Link between coupling mechanism and car body. All...

  19. Coupling between chemical kinetics and mechanics that is both nonlinear and compatible with thermodynamics.

    Science.gov (United States)

    Klika, Václav; Grmela, Miroslav

    2013-01-01

    Motivated by biological applications (e.g., bone tissue development and regeneration) we investigate coupling between mesoscopic mechanics and chemical kinetics. Governing equations of both dynamical systems are first written in a form expressing manifestly their compatibility with microscopic mechanics and thermodynamics. The same form is then required from governing equations of the coupled dynamics. The main result of the paper is an admissible form of the coupled dynamics.

  20. Unstart coupling mechanism analysis of multiple-modules hypersonic inlet.

    Science.gov (United States)

    Hu, Jichao; Chang, Juntao; Wang, Lei; Cao, Shibin; Bao, Wen

    2013-01-01

    The combination of multiplemodules in parallel manner is an important way to achieve the much higher thrust of scramjet engine. For the multiple-modules scramjet engine, when inlet unstarted oscillatory flow appears in a single-module engine due to high backpressure, how to interact with each module by massflow spillage, and whether inlet unstart occurs in other modules are important issues. The unstarted flowfield and coupling characteristic for a three-module hypersonic inlet caused by center module II and side module III were, conducted respectively. The results indicate that the other two hypersonic inlets are forced into unstarted flow when unstarted phenomenon appears on a single-module hypersonic inlet due to high backpressure, and the reversed flow in the isolator dominates the formation, expansion, shrinkage, and disappearance of the vortexes, and thus, it is the major factor of unstart coupling of multiple-modules hypersonic inlet. The coupling effect among multiple modules makes hypersonic inlet be more likely unstarted.

  1. Tuning coercive force by adjusting electric potential in solution processed Co/Pt(111) and the mechanism involved

    Science.gov (United States)

    Chang, Cheng-Hsun-Tony; Kuo, Wei-Hsu; Chang, Yu-Chieh; Tsay, Jyh-Shen; Yau, Shueh-Lin

    2017-03-01

    A combination of a solution process and the control of the electric potential for magnetism represents a new approach to operating spintronic devices with a highly controlled efficiency and lower power consumption with reduced production cost. As a paradigmatic example, we investigated Co/Pt(111) in the Bloch-wall regime. The depression in coercive force was detected by applying a negative electric potential in an electrolytic solution. The reversible control of coercive force by varying the electric potential within few hundred millivolts is demonstrated. By changing the electric potential in ferromagnetic layers with smaller thicknesses, the efficiency for controlling the tunable coercive force becomes higher. Assuming that the pinning domains are independent of the applied electric potential, an electric potential tuning-magnetic anisotropy energy model was derived and provided insights into our knowledge of the relation between the electric potential tuning coercive force and the thickness of the ferromagnetic layer. Based on the fact that the coercive force can be tuned by changing the electric potential using a solution process, we developed a novel concept of electric-potential-tuned magnetic recording, resulting in a stable recording media with a high degree of writing ability.

  2. Tuning coercive force by adjusting electric potential in solution processed Co/Pt(111) and the mechanism involved.

    Science.gov (United States)

    Chang, Cheng-Hsun-Tony; Kuo, Wei-Hsu; Chang, Yu-Chieh; Tsay, Jyh-Shen; Yau, Shueh-Lin

    2017-03-03

    A combination of a solution process and the control of the electric potential for magnetism represents a new approach to operating spintronic devices with a highly controlled efficiency and lower power consumption with reduced production cost. As a paradigmatic example, we investigated Co/Pt(111) in the Bloch-wall regime. The depression in coercive force was detected by applying a negative electric potential in an electrolytic solution. The reversible control of coercive force by varying the electric potential within few hundred millivolts is demonstrated. By changing the electric potential in ferromagnetic layers with smaller thicknesses, the efficiency for controlling the tunable coercive force becomes higher. Assuming that the pinning domains are independent of the applied electric potential, an electric potential tuning-magnetic anisotropy energy model was derived and provided insights into our knowledge of the relation between the electric potential tuning coercive force and the thickness of the ferromagnetic layer. Based on the fact that the coercive force can be tuned by changing the electric potential using a solution process, we developed a novel concept of electric-potential-tuned magnetic recording, resulting in a stable recording media with a high degree of writing ability.

  3. Unstart Coupling Mechanism Analysis of Multiple-Modules Hypersonic Inlet

    OpenAIRE

    Hu, Jichao; Chang, Juntao; Wang, Lei; Cao, Shibin; Bao, Wen

    2013-01-01

    The combination of multiplemodules in parallel manner is an important way to achieve the much higher thrust of scramjet engine. For the multiple-modules scramjet engine, when inlet unstarted oscillatory flow appears in a single-module engine due to high backpressure, how to interact with each module by massflow spillage, and whether inlet unstart occurs in other modules are important issues. The unstarted flowfield and coupling characteristic for a three-module hypersonic inlet caused by cent...

  4. Unstart Coupling Mechanism Analysis of Multiple-Modules Hypersonic Inlet

    Directory of Open Access Journals (Sweden)

    Jichao Hu

    2013-01-01

    Full Text Available The combination of multiplemodules in parallel manner is an important way to achieve the much higher thrust of scramjet engine. For the multiple-modules scramjet engine, when inlet unstarted oscillatory flow appears in a single-module engine due to high backpressure, how to interact with each module by massflow spillage, and whether inlet unstart occurs in other modules are important issues. The unstarted flowfield and coupling characteristic for a three-module hypersonic inlet caused by center module II and side module III were, conducted respectively. The results indicate that the other two hypersonic inlets are forced into unstarted flow when unstarted phenomenon appears on a single-module hypersonic inlet due to high backpressure, and the reversed flow in the isolator dominates the formation, expansion, shrinkage, and disappearance of the vortexes, and thus, it is the major factor of unstart coupling of multiple-modules hypersonic inlet. The coupling effect among multiple modules makes hypersonic inlet be more likely unstarted.

  5. Magnetically coupled resonance wireless charging technology principles and transfer mechanisms

    Science.gov (United States)

    Zhou, Jiehua; Wan, Jian; Ma, Yinping

    2017-05-01

    With the tenure of Electric-Vehicle rising around the world, the charging methods have been paid more and more attention, the current charging mode mainly has the charging posts and battery swapping station. The construction of the charging pile or battery swapping station not only require lots of manpower, material costs but the bare conductor is also easy to generate electric spark hidden safety problems, still occupies large space. Compared with the wired charging, wireless charging mode is flexible, unlimited space and location factors and charging for vehicle safety and quickly. It complements the traditional charging methods in adaptability and the independent charge deficiencies. So the researching the wireless charging system have an important practical significance and application value. In this paper, wireless charging system designed is divided into three parts: the primary side, secondary side and resonant coupling. The main function of the primary side is to generate high-frequency alternating current, so selecting CLASS-E amplifier inverter structure through the research on full bridge, half-bridge and power amplification circuit. Addition, the wireless charging system is susceptible to outside interference, frequency drift phenomenon. Combined with the wireless energy transmission characteristics, resonant parts adopt resonant coupling energy transmission scheme and the Series-Series coupling compensation structure. For the electric vehicle charging power and voltage requirements, the main circuit is a full bridge inverter and Boost circuit used as the secondary side.

  6. Investigation research on the evaluation of a coupled thermo-hydro-mechanical-chemical phenomena. Result report

    Energy Technology Data Exchange (ETDEWEB)

    Chijimatsu, Masakazu; Amemiya, Kiyoshi; Shiozaki, Isao [Hazama Corp., Tokyo (Japan); Neyama, Atsushi; Iwata, Hiroshi; Nakagawa, Koichi [Computer Software Development Co.Ltd. (Japan); Ishihara, Yoshinao; Sagawa, Hiroshi [Mitsubishi Heavy Industries Ltd., Tokyo (Japan)

    2002-02-01

    In order to realize a coupling analysis in the near field of the geological disposal system, this study has been studied on the addition of the mass transport model to the coupled thermo-hydro-mechanical analysis code (THAMES) and preliminary coupling analysis by using development environmental tool (Diffpack) for numerical analysis. (1) In order to prepare the strategy on the addition of the mass transport model to the coupled thermo-hydro-mechanical analysis code (THAMES), we have studied on the requirement of THAMES-Transport and methodology of coupling analysis. After that we set out modification plan by the Eulerian-Lagrangian (EL) method. (2) Based on the document of modification plan, we have done addition of the mass transport model to the coupled thermo-hydro-mechanical analysis code (THAMES) and carried out verification analysis in order to confirm on the accuracy of THAMES-Transport. (3) In order to understand on the behavior of NaCl in the porewater under the coupled thermo-hydro-mechanical phenomena in the HLW engineered barrier system, we have calculated coupling phenomenon by using THAMES-Transport. Transportation and concentration phenomena of NaCl are calculated but precipitation of NaCl is not occurred under the analysis conditions in this report. (4) In order to confirm about feasibility of coupling analysis under the development environmental tool (Diffpack) for numerical analysis, we have carried out on the design work and writing program of the preliminary coupling system. In this study, we have adopted existing transport model (HYDROGEOCHEM) and geochemical model (phreeqe 60) for preliminary coupling system. (5) In order to confirm program correctness of preliminary coupling system, we have carried out benchmarking analysis by using existing reactive-transport analysis code (HYDROGEOCHEM). (6) We have been prepared short-range development plan based on through the modification study of THAMES and writing program of the preliminary coupling

  7. Investigation research on the evaluation of a coupled thermo-hydro-mechanical-chemical phenomena. Outline report

    Energy Technology Data Exchange (ETDEWEB)

    Chijimatsu, Masakazu; Amemiya, Kiyoshi [Hazama Corp., Tokyo (Japan); Neyama, Atsushi; Iwata, Hiroshi; Nakagawa, Koichi [Computer Software Development Co., Ltd., Tokyo (Japan); Ishihara, Yoshinao; Shiozaki, Isao; Sagawa, Hiroshi [Mitsubishi Heavy Industries, LTD., Tokyo (Japan)

    2002-02-01

    In order to realize a coupling analysis in the near field of the geological disposal system, this study has been studied on the addition of the mass transport model to the coupled thermo-hydro-mechanical analysis code (THAMES) and preliminary coupling analysis by using development environmental tool (Diffpack) for numerical analysis. (1) In order to prepare the strategy on the addition of the mass transport model to the coupled thermo-hydro-mechanical analysis code (THAMES), we have studied on the requirement of THAMES-Transport and methodology of coupling analysis. After that we set out modification plan by the Eulerian-Lagrangian (EL) method. (2) Based on the document of modification plan, we have done addition of the mass transport model to the coupled thermo-hydro-mechanical analysis code (THAMES) and carried out verification analysis in order to confirm on the accuracy of THAMES-Transport. (3) In order to understand on the behavior of NaCl in the porewater under the coupled thermo-hydro-mechanical phenomena in the HLW engineered barrier system, we have calculated coupling phenomenon by using THAMES-Transport. Transportation and concentration phenomena of NaCl are calculated but precipitation of NaCl is not occurred under the analysis conditions in this report. (4) In order to confirm about feasibility of coupling analysis under the development environmental tool (Diffpack) for numerical analysis, we have carried out on the design work and writing program of the preliminary coupling system. In this study, we have adopted existing transport model (HYDROGEOCHEM) and geochemical model (phreeqe60) for preliminary coupling system. (5) In order to confirm program correctness of preliminary coupling system, we have carried out benchmarking analysis by using existing reactive-transport analysis code (HYDROGEOCHEM). (6) We have been prepared short-range development plan based on through the modification study of THAMES and writing program of the preliminary coupling

  8. On non-linear dynamics of a coupled electro-mechanical system

    DEFF Research Database (Denmark)

    Darula, Radoslav; Sorokin, Sergey

    2012-01-01

    , for mechanical system, is of the second order. The governing equations are coupled via linear and weakly non-linear terms. A classical perturbation method, a method of multiple scales, is used to find a steadystate response of the electro-mechanical system exposed to a harmonic close-resonance mechanical......Electro-mechanical devices are an example of coupled multi-disciplinary weakly non-linear systems. Dynamics of such systems is described in this paper by means of two mutually coupled differential equations. The first one, describing an electrical system, is of the first order and the second one...... excitation. The results are verified using a numerical model created in MATLAB Simulink environment. Effect of non-linear terms on dynamical response of the coupled system is investigated; the backbone and envelope curves are analyzed. The two phenomena, which exist in the electro-mechanical system: (a...

  9. Thermal-mechanical coupled analysis of a brake disk rotor

    Science.gov (United States)

    Belhocine, Ali; Bouchetara, Mostefa

    2013-08-01

    The main purpose of this study is to analyze the thermomechanical behavior of the dry contact between the brake disk and pads during the braking phase. The simulation strategy is based on computer code ANSYS11. The modeling of transient temperature in the disk is actually used to identify the factor of geometric design of the disk to install the ventilation system in vehicles The thermal-structural analysis is then used with coupling to determine the deformation and the Von Mises stress established in the disk, the contact pressure distribution in pads. The results are satisfactory when compared to those of the specialized literature.

  10. Exocytosis and Endocytosis: Modes, Functions, and Coupling Mechanisms*

    Science.gov (United States)

    Wu, Ling-Gang; Hamid, Edaeni; Shin, Wonchul; Chiang, Hsueh-Cheng

    2016-01-01

    Vesicle exocytosis releases content to mediate many biological events, including synaptic transmission essential for brain functions. Following exocytosis, endocytosis is initiated to retrieve exocytosed vesicles within seconds to minutes. Decades of studies in secretory cells reveal three exocytosis modes coupled to three endocytosis modes: (a) full-collapse fusion, in which vesicles collapse into the plasma membrane, followed by classical endocytosis involving membrane invagination and vesicle reformation; (b) kiss-and-run, in which the fusion pore opens and closes; and (c) compound exocytosis, which involves exocytosis of giant vesicles formed via vesicle-vesicle fusion, followed by bulk endocytosis that retrieves giant vesicles. Here we review these exo- and endocytosis modes and their roles in regulating quantal size and synaptic strength, generating synaptic plasticity, maintaining exocytosis, and clearing release sites for vesicle replenishment. Furthermore, we highlight recent progress in understanding how vesicle endocytosis is initiated and is thus coupled to exocytosis. The emerging model is that calcium influx via voltage-dependent calcium channels at the calcium microdomain triggers endocytosis and controls endocytosis rate; calmodulin and synaptotagmin are the calcium sensors; and the exocytosis machinery, including SNARE proteins (synaptobrevin, SNAP25, and syntaxin), is needed to coinitiate endocytosis, likely to control the amount of endocytosis. PMID:24274740

  11. Exocytosis and endocytosis: modes, functions, and coupling mechanisms.

    Science.gov (United States)

    Wu, Ling-Gang; Hamid, Edaeni; Shin, Wonchul; Chiang, Hsueh-Cheng

    2014-01-01

    Vesicle exocytosis releases content to mediate many biological events, including synaptic transmission essential for brain functions. Following exocytosis, endocytosis is initiated to retrieve exocytosed vesicles within seconds to minutes. Decades of studies in secretory cells reveal three exocytosis modes coupled to three endocytosis modes: (a) full-collapse fusion, in which vesicles collapse into the plasma membrane, followed by classical endocytosis involving membrane invagination and vesicle reformation; (b) kiss-and-run, in which the fusion pore opens and closes; and (c) compound exocytosis, which involves exocytosis of giant vesicles formed via vesicle-vesicle fusion, followed by bulk endocytosis that retrieves giant vesicles. Here we review these exo- and endocytosis modes and their roles in regulating quantal size and synaptic strength, generating synaptic plasticity, maintaining exocytosis, and clearing release sites for vesicle replenishment. Furthermore, we highlight recent progress in understanding how vesicle endocytosis is initiated and is thus coupled to exocytosis. The emerging model is that calcium influx via voltage-dependent calcium channels at the calcium microdomain triggers endocytosis and controls endocytosis rate; calmodulin and synaptotagmin are the calcium sensors; and the exocytosis machinery, including SNARE proteins (synaptobrevin, SNAP25, and syntaxin), is needed to coinitiate endocytosis, likely to control the amount of endocytosis.

  12. Aespoe Pillar Stability Experiment. Final coupled 3D thermo-mechanical modeling. Preliminary particle mechanical modeling

    Energy Technology Data Exchange (ETDEWEB)

    Wanne, Toivo; Johansson, Erik; Potyondy, David [Saanio and Riekkola Oy, Helsinki (Finland)

    2004-02-01

    SKB is planning to perform a large-scale pillar stability experiment called APSE (Aespoe Pillar Stability Experiment) at Aespoe HRL. The study is focused on understanding and control of progressive rock failure in hard crystalline rock and damage caused by high stresses. The elastic thermo-mechanical modeling was carried out in three dimensions because of the complex test geometry and in-situ stress tensor by using a finite-difference modeling software FLAC3D. Cracking and damage formation were modeled in the area of interest (pillar between two large scale holes) in two dimensions by using the Particle Flow Code (PFC), which is based on particle mechanics. FLAC and PFC were coupled to minimize the computer resources and the computing time. According to the modeling the initial temperature rises from 15 deg C to about 65 deg C in the pillar area during the heating period of 120 days. The rising temperature due to thermal expansion induces stresses in the pillar area and after 120 days heating the stresses have increased about 33% from the excavation induced maximum stress of 150 MPa to 200 MPa in the end of the heating period. The results from FLAC3D model showed that only regions where the crack initiation stress has exceeded were identified and they extended to about two meters down the hole wall. These could be considered the areas where damage may occur during the in-situ test. When the other hole is pressurized with a 0.8 MPa confining pressure it yields that 5 MPa more stress is needed to damage the rock than without confining pressure. This makes the damaged area in some degree smaller. High compressive stresses in addition to some tensile stresses might induce some AE (acoustic emission) activity in the upper part of the hole from the very beginning of the test and are thus potential areas where AE activities may be detected. Monitoring like acoustic emissions will be measured during the test execution. The 2D coupled PFC-FLAC modeling indicated that

  13. Catalytic bismetallative multicomponent coupling reactions: scope, applications, and mechanisms

    Science.gov (United States)

    Cho, Hee Yeon

    2014-01-01

    Catalytic reactions have played an indispensable role in organic chemistry for the last several decades. In particular, catalytic multicomponent reactions have attracted a lot of attention due to their efficiency and expediency towards complex molecule synthesis. The presence of bismetallic reagents (e.g. B–B, Si–Si, B–Si, Si–Sn, etc.) in this process renders the products enriched with various functional groups and multiple stereocenters. For this reason, catalytic bismetallative coupling is considered an effective method to generate the functional and stereochemical complexity of simple hydrocarbon substrates. This review highlights key developments of transition-metal catalyzed bismetallative reactions involving multiple π components. Specifically, it will highlight the scope, synthetic applications, and proposed mechanistic pathways of this process. PMID:24736839

  14. High order vector mode coupling mechanism based on mode matching method

    Science.gov (United States)

    Zhang, Zhishen; Gan, Jiulin; Heng, Xiaobo; Li, Muqiao; Li, Jiong; Xu, Shanhui; Yang, Zhongmin

    2017-06-01

    The high order vector mode (HOVM) coupling mechanism is investigated based on the mode matching method (MMM). In the case of strong HOVM coupling where the weakly guiding approximation fails, conventional coupling analysis methods become invalid due to the asynchronous coupling feature of the horizontal and vertical polarization components of HOVM. The MMM, which uses the interference of the local eigenmodes instead of the assumptive modes to simulate the light propagation, is adopted as a more efficient analysis method for investigating HOVM coupling processes, especially for strong coupling situations. The rules of the optimal coupling length, coupling efficiency, and mode purity in microfiber directional coupler are firstly quantitatively analyzed and summarized. Different from the specific input modes, some special new modes would be excited at the output through the strong HOVM coupling process. The analysis of HOVM coupling mechanism based on MMM could provide precise and accurate design guidance for HOVM directional coupler and mode converter, which are believed to be fundamental devices for multi-mode communication applications.

  15. Coupling Mechanism of the Tourism Industrial Network Based on Circular Economy

    OpenAIRE

    Han, Xinming; Zheng, Xiangjiang

    2009-01-01

    This paper summarizes the research situation of circular economy and tourism industrial network at home and abroad, introduces the concept and characteristics of tourism industrial network, and analyzes the coupling mechanism of tourism industrial network based on circular economy.

  16. The Effects of Mechanical Coupling on the Electrical Impedance of MEMS Resonators for UHF Filter Applications

    National Research Council Canada - National Science Library

    Hohreiter, Luke

    2004-01-01

    .... These Finite Element Analysis (FEA) simulations are performed using the ANSYS software and demonstrate the significance of mechanical coupling between MEMS longitudinal-mode bar (L-Bar) resonators...

  17. A coupled hygro-thermo-mechanical model for concrete subjected to variable environmental conditions

    National Research Council Canada - National Science Library

    Gasch, Tobias; Malm, Richard; Ansell, Anders

    2016-01-01

    .... Variations of these fields must therefore be included implicitly in an analysis. This paper presents a coupled hygro-thermo-mechanical model for hardened concrete based on the framework of the Microprestress-Solidification theory...

  18. Magnetic coupling mechanisms in particle/thin film composite systems

    Directory of Open Access Journals (Sweden)

    Giovanni A. Badini Confalonieri

    2010-12-01

    Full Text Available Magnetic γ-Fe2O3 nanoparticles with a mean diameter of 20 nm and size distribution of 7% were chemically synthesized and spin-coated on top of a Si-substrate. As a result, the particles self-assembled into a monolayer with hexagonal close-packed order. Subsequently, the nanoparticle array was coated with a Co layer of 20 nm thickness. The magnetic properties of this composite nanoparticle/thin film system were investigated by magnetometry and related to high-resolution transmission electron microscopy studies. Herein three systems were compared: i.e. a reference sample with only the particle monolayer, a composite system where the particle array was ion-milled prior to the deposition of a thin Co film on top, and a similar composite system but without ion-milling. The nanoparticle array showed a collective super-spin behavior due to dipolar interparticle coupling. In the composite system, we observed a decoupling into two nanoparticle subsystems. In the ion-milled system, the nanoparticle layer served as a magnetic flux guide as observed by magnetic force microscopy. Moreover, an exchange bias effect was found, which is likely to be due to oxygen exchange between the iron oxide and the Co layer, and thus forming of an antiferromagnetic CoO layer at the γ-Fe2O3/Co interface.

  19. Multiscale Simulation Framework for Coupled Fluid Flow and Mechanical Deformation

    Energy Technology Data Exchange (ETDEWEB)

    Tchelepi, Hamdi

    2014-11-14

    A multiscale linear-solver framework for the pressure equation associated with flow in highly heterogeneous porous formations was developed. The multiscale based approach is cast in a general algebraic form, which facilitates integration of the new scalable linear solver in existing flow simulators. The Algebraic Multiscale Solver (AMS) is employed as a preconditioner within a multi-stage strategy. The formulations investigated include the standard MultiScale Finite-Element (MSFE) andMultiScale Finite-Volume (MSFV) methods. The local-stage solvers include incomplete factorization and the so-called Correction Functions (CF) associated with the MSFV approach. Extensive testing of AMS, as an iterative linear solver, indicate excellent convergence rates and computational scalability. AMS compares favorably with advanced Algebraic MultiGrid (AMG) solvers for highly detailed three-dimensional heterogeneous models. Moreover, AMS is expected to be especially beneficial in solving time-dependent problems of coupled multiphase flow and transport in large-scale subsurface formations.

  20. Metamaterial tuning by manipulation of near-field interaction

    CERN Document Server

    Powell, David A; Gorkunov, Maxim; Shadrivov, Ilya V; Kivshar, Yuri S

    2009-01-01

    We analyze the near-field interaction between the resonant sub-wavelength elements of a metamaterial. We show that by adjusting the lattice configuration it becomes possible to manipulate this near-field interaction, and thus tune the magnetic response of a lattice of split-ring resonators. By studying the case of a pair of split-ring resonators, we are able to show the coupling mechanisms at work and how they influence the response of the complete metamaterial structure. We use the results of this analysis to explain experimentally observed tuning of microwave metamaterial arrays.

  1. Lamins and nesprin-1 mediate inside-out mechanical coupling in muscle cell precursors through FHOD1.

    Science.gov (United States)

    Schwartz, Christine; Fischer, Martina; Mamchaoui, Kamel; Bigot, Anne; Lok, Thevy; Verdier, Claude; Duperray, Alain; Michel, Richard; Holt, Ian; Voit, Thomas; Quijano-Roy, Suzanna; Bonne, Gisèle; Coirault, Catherine

    2017-04-28

    LINC complexes are crucial for the response of muscle cell precursors to the rigidity of their environment, but the mechanisms explaining this behaviour are not known. Here we show that pathogenic mutations in LMNA or SYNE-1 responsible for severe muscle dystrophies reduced the ability of human muscle cell precursors to adapt to substrates of different stiffness. Plated on muscle-like stiffness matrix, mutant cells exhibited contractile stress fibre accumulation, increased focal adhesions, and higher traction force than controls. Inhibition of Rho-associated kinase (ROCK) prevented cytoskeletal defects, while inhibiting myosin light chain kinase or phosphorylation of focal adhesion kinase was ineffective. Depletion or inactivation of a ROCK-dependent regulator of actin remodelling, the formin FHOD1, largely rescued morphology in mutant cells. The functional integrity of lamin and nesprin-1 is thus required to modulate the FHOD1 activity and the inside-out mechanical coupling that tunes the cell internal stiffness to match that of its soft, physiological-like environment.

  2. 3-D coupled electric mechanics for MEMS: Applications of COSOLVE-EM

    NARCIS (Netherlands)

    Gilbert, J.R.; Legtenberg, R.; Legtenberg, Rob; Senturia, S.D.

    1995-01-01

    Micro-electro-mechanical systems (MEMS) are often designed on scales at which electrostatic forces are capable of moving or deforming the parts of the system. In this regime accurate prediction of device behavior may require 3D coupled simulations between the electrostatic and mechanical domains. We

  3. Chemo-mechanical coupling in molecular motors interpreted through the uncertainty relations

    Energy Technology Data Exchange (ETDEWEB)

    Jomova, Klaudia, E-mail: kjomova@ukf.sk [Department of Chemistry, Faculty of Natural Sciences, Constantine The Philosopher University, SK-949 74 Nitra (Slovakia); Zelenicky, L' ubomir [Department of Physics, Faculty of Natural Sciences, Constantine The Philosopher University, SK-949 74 Nitra (Slovakia); Morris, Harry [School of Pharmacy and Chemistry, Liverpool John Moores University, Liverpool L3 3AF (United Kingdom); Mazur, Milan [Institute of Physical Chemistry and Chemical Physics, Faculty of Chemical and Food Technology, Slovak Technical University, SK-812 37 Bratislava (Slovakia); Valko, Marian, E-mail: marian.valko@stuba.sk [Institute of Physical Chemistry and Chemical Physics, Faculty of Chemical and Food Technology, Slovak Technical University, SK-812 37 Bratislava (Slovakia)

    2010-06-16

    Graphical abstract: A new, unique representation of biophysical uncertainty relations have been formulated by combining both the quantum mechanical and of statistical mechanics uncertainty relations into a single entity. The biophysical uncertainty relations are especially suitable for the estimation of chemo-mechanical coupling between chemical and physical variables in molecular motors. This statement is supported by examples on myosin motors under conditions of low load and sub-piconewton force fluctuations of actomyosin interacting, in vitro, with a single actin filament. We have approached the description of chemo-mechanical coupling only in terms of macroscopic quantities which are regarded as stochastic variables. - Abstract: A new, unique representation of biophysical uncertainty relations have been formulated by combining both the quantum mechanical and of statistical mechanics uncertainty relations into a single entity. The biophysical uncertainty relations are especially suitable for the estimation of chemo-mechanical coupling between chemical and physical variables in molecular motors. This statement is supported by examples on myosin motors under conditions of low load and sub-piconewton force fluctuations of actomyosin interacting, in vitro, with a single actin filament. We have approached the description of chemo-mechanical coupling only in terms of macroscopic quantities which are regarded as stochastic variables.

  4. Coupling of single quantum emitters to plasmons propagating on mechanically etched wires

    DEFF Research Database (Denmark)

    Kumar, Shailesh; Huck, Alexander; Lu, Ying-Wei

    2013-01-01

    We demonstrate the coupling of a single nitrogen vacancy center in a nanodiamond to propagating plasmonic modes of mechanically etched silver nanowires. The mechanical etch is performed on single crystalline silver nanoplates by the tip of an atomic force microscope cantilever to produce wires wi...

  5. Band-gap engineering by molecular mechanical strain-induced giant tuning of the luminescence in colloidal amorphous porous silicon nanostructures

    KAUST Repository

    Mughal, Asad Jahangir

    2014-01-01

    Nano-silicon is a nanostructured material in which quantum or spatial confinement is the origin of the material\\'s luminescence. When nano-silicon is broken into colloidal crystalline nanoparticles, its luminescence can be tuned across the visible spectrum only when the sizes of the nanoparticles, which are obtained via painstaking filtration methods that are difficult to scale up because of low yield, vary. Bright and tunable colloidal amorphous porous silicon nanostructures have not yet been reported. In this letter, we report on a 100 nm modulation in the emission of freestanding colloidal amorphous porous silicon nanostructures via band-gap engineering. The mechanism responsible for this tunable modulation, which is independent of the size of the individual particles and their distribution, is the distortion of the molecular orbitals by a strained silicon-silicon bond angle. This mechanism is also responsible for the amorphous-to-crystalline transformation of silicon. This journal is

  6. Band-gap engineering by molecular mechanical strain-induced giant tuning of the luminescence in colloidal amorphous porous silicon nanostructures.

    Science.gov (United States)

    Mughal, A; El Demellawi, J K; Chaieb, Sahraoui

    2014-12-14

    Nano-silicon is a nanostructured material in which quantum or spatial confinement is the origin of the material's luminescence. When nano-silicon is broken into colloidal crystalline nanoparticles, its luminescence can be tuned across the visible spectrum only when the sizes of the nanoparticles, which are obtained via painstaking filtration methods that are difficult to scale up because of low yield, vary. Bright and tunable colloidal amorphous porous silicon nanostructures have not yet been reported. In this letter, we report on a 100 nm modulation in the emission of freestanding colloidal amorphous porous silicon nanostructures via band-gap engineering. The mechanism responsible for this tunable modulation, which is independent of the size of the individual particles and their distribution, is the distortion of the molecular orbitals by a strained silicon-silicon bond angle. This mechanism is also responsible for the amorphous-to-crystalline transformation of silicon.

  7. CO2-ECBM related coupled physical and mechanical transport processes

    Science.gov (United States)

    Gensterblum, Yves; Satorius, Michael; Busch, Andreas; Krooß, Bernhard

    2013-04-01

    The interrelation of cleat transport processes and mechanical properties was investigated by permeability tests at different stress levels (60% to 130% of in-situ stress) with sorbing (CH4, CO2) and inert gases (N2, Ar, He) on a sub bituminous A coal from the Surat Basin, Queensland Australia. From the flow tests under controlled triaxial stress conditions the Klinkenberg-corrected "true" permeability coefficients and the Klinkenberg slip factors were derived. The "true"-, absolute or Klinkenberg corrected permeability shows a gas type dependence. Following the approach of Seidle et al. (1992) the cleat volume compressibility (cf) was calculated from observed changes in apparent permeability upon variation of external stress (at equal mean gas pressures). The observed effects also show a clear dependence on gas type. Due to pore or cleat compressibility the cleat aperture decreases with increasing effective stress. Vice versa we observe with increasing mean pressure at lower confining pressure an increase in permeability which we attribute to a cleat aperture widening. The cleat volume compressibility (cf) also shows a dependence on the mean pore pressure. Non-sorbing gases like helium and argon show higher apparent permeabilities than sorbing gases like methane. Permeability coefficients measured with successively increasing mean gas pressures were consistently lower than those determined at decreasing mean gas pressures. This permeability hysteresis is in accordance with results reported by Harpalani and McPherson (1985). The kinetics of matrix transport processes were studied by sorption tests on different particle sizes at various moisture contents and temperatures (cf. Busch et al., 2006). Methane uptake rates were determined from the pressure decline curves recorded for each particle-size fraction, and "diffusion coefficients" were calculated using several unipore and bidisperse diffusion models. While the CH4 sorption capacity of moisture-equilibrated coals

  8. A three-dimensional coupled thermo-hydro-mechanical model for deformable fractured geothermal systems

    DEFF Research Database (Denmark)

    Salimzadeh, Saeed; Paluszny, Adriana; Nick, Hamidreza M.

    2018-01-01

    A fully coupled thermal-hydraulic-mechanical (THM) finite element model is presented for fractured geothermal reservoirs. Fractures are modelled as surface discontinuities within a three-dimensional matrix. Non-isothermal flow through the rock matrix and fractures are defined and coupled to a mec......A fully coupled thermal-hydraulic-mechanical (THM) finite element model is presented for fractured geothermal reservoirs. Fractures are modelled as surface discontinuities within a three-dimensional matrix. Non-isothermal flow through the rock matrix and fractures are defined and coupled....... The model has been validated against several analytical solutions, and applied to study the effects of the deformable fractures on the injection of cold water in fractured geothermal systems. Results show that the creation of flow channelling due to the thermal volumetric contraction of the rock matrix...

  9. Functionalized SiC nanocrystals for tuning of optical, thermal, mechanical and electrical properties of polyvinyl alcohol

    DEFF Research Database (Denmark)

    Saini, Isha; Sharma, Annu; Dhiman, Rajnish

    2017-01-01

    Polyvinyl alcohol (PVA)-SiC nanocomposite films were prepared by incorporating functionalized Silicon Carbide (f-SiC) nanocrystals in PVA matrix. Structural characterization of SiC nanocrystals before and after the functionalization was carried out using Fourier transform infrared spectroscopy (F...... mechanism responsible for charge transport in PVA-SiC nanocomposite films was found to be voltage dependent. Schottky mechanism is the dominant conduction mechanism at high voltages whereas Poole Frenkel mechanism dominates at low voltages....

  10. Three-Dimensional Field-Scale Coupled Thermo-Hydro-Mechanical Modeling: Parallel Computing Implementation

    OpenAIRE

    Vardon, Philip James; Cleall, Peter John; Thomas, Hywel Rhys; Philp, Roger Norman; Banicescu, Ioana

    2011-01-01

    An approach for the simulation of three-dimensional field-scale coupled thermo-hydro-mechanical problems is presented, including the implementation of parallel computation algorithms. The approach is designed to allow three-dimensional large-scale coupled simulations to be undertaken in reduced time. Owing to progress in computer technology, existing parallel implementations have been found to be ineffective, with the time taken for communication dominating any reduction in time gained by spl...

  11. Experimental study of the irrational phase synchronization of coupled nonidentical mechanical metronomes.

    Directory of Open Access Journals (Sweden)

    Zhiwen Song

    Full Text Available It has recently been observed in numerical simulations that the phases of two coupled nonlinear oscillators can become locked into an irrational ratio, exhibiting the phenomenon of irrational phase synchronization (IPS [Phys. Rev. E 69, 056228 (2004]. Here, using two coupled nonidentical periodic mechanical metronomes, we revisit this interesting phenomenon through experimental studies. It is demonstrated that under suitable couplings, the phases of the metronomes indeed can become locked into irrational ratios. Numerical simulations confirm the experimental observations and also reveal that in the IPS state, the system dynamics are chaotic. Our studies provide a solid step toward further studies of IPS.

  12. DECOVALEX III PROJECT. Thermal-Hydro-Mechanical Coupled Processes in Safety Assessments. Report of Task 4

    Energy Technology Data Exchange (ETDEWEB)

    Andersson, Johan [JA Streamflow AB, Aelvsjoe (Sweden)

    2005-02-15

    A part (Task 4) of the International DECOVALEX III project on coupled thermo-hydro-mechanical (T-H-M) processes focuses on T-H-M modelling applications in safety and performance assessment of deep geological nuclear waste repositories. A previous phase, DECOVALEX II, saw a need to improve such modelling. In order to address this need Task 4 of DECOVALEX III has: Analysed two major T-H-M experiments (Task 1 and Task 2) and three different Bench Mark Tests (Task 3) set-up to explore the significance of T-H-M in some potentially important safety assessment applications. Compiled and evaluated the use of T-H-M modelling in safety assessments at the time of the year 2000. Organised a forum a forum of interchange between PA-analysts and THM modelers at each DECOVALEX III workshop. Based on this information the current report discusses the findings and strives for reaching recommendations as regards good practices in addressing coupled T-H-M issues in safety assessments. The full development of T-H-M modelling is still at an early stage and it is not evident whether current codes provide the information that is required. However, although the geosphere is a system of fully coupled processes, this does not directly imply that all existing coupled mechanisms must be represented numerically. Modelling is conducted for specific purposes and the required confidence level should be considered. It is necessary to match the confidence level with the modelling objective. Coupled THM modelling has to incorporate uncertainties. These uncertainties mainly concern uncertainties in the conceptual model and uncertainty in data. Assessing data uncertainty is important when judging the need to model coupled processes. Often data uncertainty is more significant than the coupled effects. The emphasis on the need for THM modelling differs among disciplines. For geological radioactive waste disposal in crystalline and other similar hard rock formations DECOVALEX III shows it is essential to

  13. Spatially explicit, nano-mechanical models of the muscle half-sarcomere: Implications for biomechanical tuning in atrophy and fatigue

    Science.gov (United States)

    Kataoka, Aya; Tanner, Bertrand C. W.; Macpherson, J. Michael; Xu, Xiangrong; Wang, Qi; Regnier, Michael; Daniel, Thomas L.; Chase, P. Bryant

    2007-01-01

    Astronaut biomechanical performance depends on a wide variety of factors. Results from computational modelling suggest that muscle function—a key component of performance—could be modulated by compliance of the contractile filaments in muscle, especially when force is low such as transient Ca activation in a twitch, reduced activation in muscle fatigue encountered during EVA, or perhaps atrophy during prolonged space flight. We used Monte-Carlo models to investigate the hypotheses that myofilament compliance influences muscle function during a twitch, and also modulates the effects of cooperative interactions between contractile proteins on force generation. Peak twitch force and the kinetics of force decay were both decreased, while tension cost was increased, when myofilament compliance was increased relative to physiological values. Both the apparent Ca sensitivity and cooperativity of activation of steady-state isometric force were altered by myofilament compliance even when there were no explicit interactions included between binding sites. The effects of cooperative interactions between adjacent regulatory units were found to be greater than either the effect of myofilament compliance on apparent cooperativity of activation or that due to myosin cross-bridge-induced cooperativity. These results indicate that muscle function may be "tuned" at the molecular level, particularly under conditions of reduced Ca activation.

  14. In vivo absolute quantification for mouse muscle metabolites using an inductively coupled synthetic signal injection method and newly developed (1) H/(31) P dual tuned probe.

    Science.gov (United States)

    Lee, Donghoon; Marro, Kenneth; Mathis, Mark; Shankland, Eric; Hayes, Cecil

    2014-04-01

    To obtain robust estimates of (31) P metabolite content in mouse skeletal muscles using our recently developed MR absolute quantification method and a custom-built (1) H/(31) P dual tuned radiofrequency (RF) coil optimized for mouse leg. We designed and fabricated a probe consisting of two dual tuned (1) H/(31) P solenoid coils: one leg was inserted to each solenoid. The mouse leg volume coil was incorporated with injector coils for MR absolute quantification. The absolute quantification method uses a synthetic reference signal injection approach and solves several challenges in MR absolute quantification including changes of coil loading and receiver gains. The (1) H/(31) P dual tuned probe was composed of two separate solenoid coils, one for each leg, to increase coil filling factors and signal-to-noise ratio. Each solenoid was equipped with a second coil to allow injection of reference signals. (31) P metabolite concentrations determined for normal mice were well within the expected range reported in the literature. We developed an RF probe and an absolute quantification approach adapted for mouse skeletal muscle. Copyright © 2014 Wiley Periodicals, Inc.

  15. In vivo absolute quantification for mouse muscle metabolites using an inductively coupled synthetic signal injection method and newly developed 1H/31P dual tuned probe

    Science.gov (United States)

    Lee, Donghoon; Marro, Kenneth; Mathis, Mark; Shankland, Eric; Hayes, Cecil

    2013-01-01

    Purpose To obtain robust estimates of 31P metabolite content in mouse skeletal muscles using our recently developed MR absolute quantification method and a custom-built 1H/31P dual tuned radiofrequency (RF) coil optimized for mouse leg. Materials and Methods We designed and fabricated a probe consisting of two dual tuned 1H/31P solenoid coils: one leg was inserted to each solenoid. The mouse leg volume coil was incorporated with injector coils for MR absolute quantification. The absolute quantification method uses a synthetic reference signal injection approach and solves several challenges in MR absolute quantification including changes of coil loading and receiver gains. Results The 1H/31P dual tuned probe was composed of two separate solenoid coils, one for each leg, to increase coil filling factors and signal-to-noise ratio. Each solenoid was equipped with a second coil to allow injection of reference signals. 31P metabolite concentrations determined for normal mice were well within the expected range reported in the literature. Conclusion We developed an RF probe and an absolute quantification approach adapted for mouse skeletal muscle. PMID:24464912

  16. Identical Hydrogen-Bonding Strength of the Retinal Schiff Base between Primate Green- and Red-Sensitive Pigments: New Insight into Color Tuning Mechanism.

    Science.gov (United States)

    Katayama, Kota; Okitsu, Takashi; Imai, Hiroo; Wada, Akimori; Kandori, Hideki

    2015-04-02

    Three aspects are generally considered in the color-tuning mechanism of vision: (I) chromophore distortion, (II) electrostatic interaction between the protonated Schiff base and counterion, and (III) polarity around the β-ionone ring and polyene chain. Primate green- and red-sensitive proteins are highly homologous but display maximum absorption at 530 and 560 nm, respectively. In the present study, the N-D stretching frequency of monkey green-sensitive protein was identified by using C15-D retinal. The hydrogen-bonding strength between monkey green and red was identical. Together with a previous resonance Raman study, we conclude that the 30 nm difference originates exclusively from the polarity around the β-ionone ring and polyene chain. Three amino acids (Ala, Phe, and Ala in monkey green and Ser, Tyr, and Thr in monkey red, respectively) may be responsible for color tuning together with protein-bound water molecules around the β-ionone ring and polyene chain but not at the Schiff base region.

  17. Computer simulations of neural mechanisms explaining upper and lower limb excitatory neural coupling

    Directory of Open Access Journals (Sweden)

    Ferris Daniel P

    2010-12-01

    Full Text Available Abstract Background When humans perform rhythmic upper and lower limb locomotor-like movements, there is an excitatory effect of upper limb exertion on lower limb muscle recruitment. To investigate potential neural mechanisms for this behavioral observation, we developed computer simulations modeling interlimb neural pathways among central pattern generators. We hypothesized that enhancement of muscle recruitment from interlimb spinal mechanisms was not sufficient to explain muscle enhancement levels observed in experimental data. Methods We used Matsuoka oscillators for the central pattern generators (CPG and determined parameters that enhanced amplitudes of rhythmic steady state bursts. Potential mechanisms for output enhancement were excitatory and inhibitory sensory feedback gains, excitatory and inhibitory interlimb coupling gains, and coupling geometry. We first simulated the simplest case, a single CPG, and then expanded the model to have two CPGs and lastly four CPGs. In the two and four CPG models, the lower limb CPGs did not receive supraspinal input such that the only mechanisms available for enhancing output were interlimb coupling gains and sensory feedback gains. Results In a two-CPG model with inhibitory sensory feedback gains, only excitatory gains of ipsilateral flexor-extensor/extensor-flexor coupling produced reciprocal upper-lower limb bursts and enhanced output up to 26%. In a two-CPG model with excitatory sensory feedback gains, excitatory gains of contralateral flexor-flexor/extensor-extensor coupling produced reciprocal upper-lower limb bursts and enhanced output up to 100%. However, within a given excitatory sensory feedback gain, enhancement due to excitatory interlimb gains could only reach levels up to 20%. Interconnecting four CPGs to have ipsilateral flexor-extensor/extensor-flexor coupling, contralateral flexor-flexor/extensor-extensor coupling, and bilateral flexor-extensor/extensor-flexor coupling could enhance

  18. Integrated unaligned resonant modulator tuning

    Science.gov (United States)

    Zortman, William A.; Lentine, Anthony L.

    2017-10-03

    Methods and systems for tuning a resonant modulator are disclosed. One method includes receiving a carrier signal modulated by the resonant modulator with a stream of data having an approximately equal number of high and low bits, determining an average power of the modulated carrier signal, comparing the average power to a predetermined threshold, and operating a tuning device coupled to the resonant modulator based on the comparison of the average power and the predetermined threshold. One system includes an input structure, a plurality of processing elements, and a digital control element. The input structure is configured to receive, from the resonant modulator, a modulated carrier signal. The plurality of processing elements are configured to determine an average power of the modulated carrier signal. The digital control element is configured to operate a tuning device coupled to the resonant modulator based on the average power of the modulated carrier signal.

  19. Research on Thermal-Mechanical Coupling Modeling and Simulation of the Spindle Feed System of Machine Tool

    Directory of Open Access Journals (Sweden)

    Xu Jianhua

    2017-01-01

    Full Text Available Performance of spindle feed system affects the accuracy of machine tools directly. Aiming at the problem that most research works focused on mechanical characteristics or thermal characteristics of the feed system so far, the thermal-mechanical coupling characteristic is studied in this paper. The coupling mechanism and theoretical model are established for a machine tool feed system, its coupling modal and harmonic response are simulated and analyzed by the FEM software. By comparing with the mechanical characteristics, thermal-mechanical coupling characteristics has directly influence on the dynamic performance of spindle feed system, its displacement amplitude is significantly weakened.

  20. A new coupling mechanism between two graphene electron waveguides for ultrafast switching

    Science.gov (United States)

    Huang, Wei; Liang, Shi-Jun; Kyoseva, Elica; Ang, Lay Kee

    2018-03-01

    In this paper, we report a novel coupling between two graphene electron waveguides, in analogy the optical waveguides. The design is based on the coherent quantum mechanical tunneling of Rabi oscillation between the two graphene electron waveguides. Based on this coupling mechanism, we propose that it can be used as an ultrafast electronic switching device. Based on a modified coupled mode theory, we construct a theoretical model to analyze the device characteristics, and predict that the switching speed is faster than 1 ps and the on–off ratio exceeds 106. Due to the long mean free path of electrons in graphene at room temperature, the proposed design avoids the limitation of low temperature operation required in the traditional design by using semiconductor quantum-well structure. The layout of our design is similar to that of a standard complementary metal-oxide-semiconductor transistor that should be readily fabricated with current state-of-art nanotechnology.

  1. Work Function Tuning in Sub-20nm Titanium Nitride (TiN) Metal Gate: Mechanism and Engineering

    KAUST Repository

    Hasan, Mehdi

    2011-07-01

    Scaling of transistors (the building blocks of modern information age) provides faster computation at the expense of excessive power dissipation. Thus to address these challenges, high-k/metal gate stack has been introduced in commercially available microprocessors from 2007. Since then titanium nitride (TiN) metal gate’s work function (Wf) tunability with its thickness (thickness increases, work function increases) is a well known phenomenon. Many hypotheses have been made over the years which include but not limited to: trap charge and metal gate nucleation, nitrogen concentration, microstructure agglomeration and global stress, metal oxide formation, and interfacial oxide thickness. However, clear contradictions exist in these assumptions. Also, nearly all these reports skipped a comprehensive approach to explain this complex paradigm. Therefore, in this work we first show a comprehensive physical investigation using transmission electron microcopy/electron energy loss spectroscopy (TEM/EELS), x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS) and secondary ion mass spectroscopy (SIMS) to show replacement of oxygen by nitrogen in the metal/dielectric interface, formation of TiONx, reduction of Ti/N concentration and grain size increment happen with TiN thickness increment and thus may increase the work function. Then, using these finding, we experimentally show 100meV of work function modulation in 10nm TiN Metal-oxide-semiconductor capacitor by using low temperature oxygen annealing. A low thermal budget flow (replicating gate-last) shows similar work function boost up. Also, a work function modulation of 250meV has been possible using oxygen annealing and applying no thermal budget. On the other hand, etch-back of TiN layer can decrease the work function. Thus this study quantifies role of various factors in TiN work function tuning; it also reproduces the thickness varied TiN work function modulation in single thickness TiN thus reducing the

  2. Fracture mechanisms in biopolymer films using coupling of mechanical analysis and high speed visualization technique

    NARCIS (Netherlands)

    Paes, S.S.; Yakimets, I.; Wellner, N.; Hill, S.E.; Wilson, R.H.; Mitchell, J.R.

    2010-01-01

    The aim of this study was to provide a detailed description of the fracture mechanisms in three different biopolymer thin materials: gelatin, hydroxypropyl cellulose (HPC) and cassava starch films. That was achieved by using a combination of fracture mechanics methodology and in situ visualization

  3. High-performance coupled poro-hydro-mechanical models to resolve fluid escape pipes

    Science.gov (United States)

    Räss, Ludovic; Makhnenko, Roman; Podladchikov, Yury

    2017-04-01

    Field observations and laboratory experiments exhibit inelastic deformation features arising in many coupled settings relevant to geo-applications. These irreversible deformations and their specific patterns suggest a rather ductile or brittle mechanism, such as viscous creep or micro cracks, taking place on both geological (long) and human (short) timescales. In order to understand the underlying mechanisms responsible for these deformation features, there is a current need to accurately resolve the non-linearities inherent to strongly coupled physical processes. Among the large variety of modelling tools and softwares available nowadays in the community, very few are capable to efficiently solve coupled systems with high accuracy in both space and time and run efficiently on modern hardware. Here, we propose a robust framework to solve coupled multi-physics hydro-mechanical processes on very high spatial and temporal resolution in both two and three dimensions. Our software relies on the Finite-Difference Method and a pseudo-transient scheme is used to converge to the implicit solution of the system of poro-visco-elasto-plastic equations at each physical time step. The rheology including viscosity estimates for major reservoir rock types is inferred from novel lab experiments and confirms the ease of flow of sedimentary rocks. Our results propose a physical mechanism responsible for the generation of high permeability pathways in fluid saturated porous media and predict their propagation in rates observable on operational timescales. Finally, our software scales linearly on more than 5000 GPUs.

  4. Thermomechanical modeling of the thermo-order-mechanical coupling behaviors in liquid crystal elastomers

    Science.gov (United States)

    Jin, Lihua; Zeng, Zhi; Huo, Yongzhong

    2010-11-01

    Liquid crystal elastomer is a kind of anisotropic polymeric material, with complicated micro-structures and thermo-order-mechanical coupling behaviors. In this paper, we propose a method to systematically model these coupling behaviors. We derive the constitutive model in full tensor structure according to the Clausius-Duhem inequality. Two of the constitutive equations represent the mechanical equilibrium and the other two represent the phase equilibrium. Choosing the total free energy as the combination of the neo-classical free energy and the Landau-de Gennes nematic free energy, we obtain the Cauchy stress-deformation gradient relation and the order-mechanical coupling equations. We find the analytical homogeneous solutions of the deformation for the typical mechanical loadings, such as uniaxial stretch, and simple shear in any directions. We also compare the compression behavior of prolate liquid crystal elastomers with the stretch behavior of oblate liquid crystal elastomers. As a result, the stress, strain, temperature, order parameter, biaxiality and the direction of the director of liquid crystal elastomers couple with each other. When the prolate liquid crystal elastomer sample is stretched in the direction parallel to its director, the deviatoric stress makes the mesogens more order and increase the transition temperature. When the sample is sheared or stretched in the direction non-parallel to the director, the director of the liquid crystal elastomer will rotate, and the biaxiality will be induced. Because of the order-mechanical coupling, under infinitesimal deformation, liquid crystal elastomer has anisotropic Young's modulus and zero shear modulus in the direction parallel or perpendicular to the director. While for the oblate liquid crystal elastomers, the stretch parallel to the director will cause the rotation of the director and induce the biaxiality.

  5. Catalytic coupling reaction mechanism of 4-nitrobenzenethiol on silver clusters: a density functional theoretical study.

    Science.gov (United States)

    Chen, Xiao; Wei, Wei; Li, Laicai; Liu, Liuxie; Pan, Rui; Tian, Anmin

    2017-10-23

    The catalytic coupling reaction mechanism of the transformation from 4-nitrobenzenethiol (4-NBT) to 4,4'-dimercaptoazobenzene (4,4'-DMAB) on a silver cluster was studied by density functional theory. Reactants, intermediates, transition states and products were optimized with the B3LYP method using the 6-311 + G(d,p) basis set (Ag using the pseudo potential basis set of LanL2DZ). Transition states and intermediates were confirmed by the corresponding vibration analysis and intrinsic reaction coordinates (IRC). Consistent with literature reports, the key point of the transformation from 4-NBT absorbed on the surface of Ag 5 clusters to 4,4'-DMAB is the elimination of two O atoms on the amino group. Meanwhile, the catalytic coupling reaction of 4-nitrobenzenethiol on a silver cluster is easy to carry out under irradiation. The possibility of "inter system channeling" (ISC) between different potential energy surfaces in the coupling reaction of 4-NBT is further discussed. The irradiation has an auxiliary catalytic effect on the coupling reaction. Our research results can explain the observed experimental phenomena. Graphical abstract Catalytic coupling reaction mechanism of the transformation from 4-nitrothiophenol (4-NBT) to 4,4'-dimercaptoazobenzene (4,4'-DMAB) on silver clusters studied by density functional theory.

  6. A general solution for one dimensional chemo-mechanical coupled hydrogel rod

    Science.gov (United States)

    Wang, Xing-Quan; Yang, Qing-Sheng

    2017-10-01

    Smart hydrogels are environmentally sensitive hydrogels, which can produce a sensitive response to external stimuli, and often exhibit the characteristics of multi filed coupling. In this paper, a hydrogel rod under chemo-mechanical coupling was analytically studied based on a poroelastical model. The already known constitutive and governing equations were simplified into the one dimensional case, then two different boundary conditions were considered. The expressions of concentration, displacement, chemical potential and stress related to time were obtained in a series form. Examples illustrate the interaction mechanism of chemical and mechanical effect. It was found that there was a balance state in the diffusion of concentration and the diffusion process could lead to the expansion or the stress change of the hydrogel rod.

  7. Surface-Tuned Co3O4 Nanoparticles Dispersed on Nitrogen-Doped Graphene as an Efficient Cathode Electrocatalyst for Mechanical Rechargeable Zinc-Air Battery Application.

    Science.gov (United States)

    Singh, Santosh K; Dhavale, Vishal M; Kurungot, Sreekumar

    2015-09-30

    The most vital component of the fuel cells and metal-air batteries is the electrocatalyst, which can facilitate the oxygen reduction reaction (ORR) at a significantly reduced overpotential. The present work deals with the development of surface-tuned cobalt oxide (Co3O4) nanoparticles dispersed on nitrogen-doped graphene as a potential ORR electrocatalyst possessing some unique advantages. The thermally reduced nitrogen-doped graphene (NGr) was decorated with three different morphologies of Co3O4 nanoparticles, viz., cubic, blunt edged cubic, and spherical, by using a simple hydrothermal method. We found that the spherical Co3O4 nanoparticle supported NGr catalyst (Co3O4-SP/NGr-24h) has acquired a significant activity makeover to display the ORR activity closely matching with the state-of-the-art Pt supported carbon (PtC) catalyst in alkaline medium. Subsequently, the Co3O4-SP/NGr-24h catalyst has been utilized as the air electrode in a Zn-air battery, which was found to show comparable performance to the system derived from PtC. Co3O4-SP/NGr-24h catalyst has shown several hours of flat discharge profile at the discharge rates of 10, 20, and 50 mA/cm(2) with a specific capacity and energy density of ~590 mAh/g-Zn and ~840 Wh/kg-Zn, respectively, in the primary Zn-air battery system. In conjunction, Co3O4-SP/NGr-24h has outperformed as an air electrode in mechanical rechargeable Zn-air battery as well, which has shown consistent flat discharge profile with minimal voltage loss at a discharge rate of 50 mA/cm(2). The present results, thus demonstrate that the proper combination of the tuned morphology of Co3O4 with NGr will be a promising and inexpensive material for efficient and ecofriendly cathodes for Zn-air batteries.

  8. Mechanisms of AZO workfunction tuning for anode use in OLEDs: Surface dipole manipulation with plasma treatments versus nanoscale WOx and VOx interfacial layers

    Science.gov (United States)

    Jha, Jitendra Kumar; Sun, Wei; Du, Jincheng; Shepherd, Nigel D.

    2017-05-01

    Zinc oxide (ZnO) and aluminum doped zinc oxide (AZO) are potential low cost alternative anodes to indium tin oxide (ITO) for organic light emitting diodes (OLEDs). However, their smaller workfunctions compared to ITO lead to higher hole injection barriers, and methods of tuning their workfunctions are of significant technological interest. Ultraviolet and x-ray photoelectron spectroscopies together with density functional theory based first principles calculations indicate that with CFx plasma treatments, increased workfunction can be achieved by -CF3 or -F adsorption on ZnO surfaces, due to creation of a surface dipole moment with electron transfer to F. Modification of AZO surfaces with nanoscopic (˜3 nm) VOx and WOx layers yielded workfunction increases due to the larger workfunction of the add-layers. Deviations from stoichiometry (oxygen vacancies) result in reduced metal cations (W5+, W4+, V4+, and V3+), leading to partial filling of the metal d band, and formation of associated gap states. Current-voltage characterization of hole-only devices reveals that the increased workfunction of the surface modified anodes facilitated improved band alignment and hole injection compared to as-deposited AZO. The luminous efficiency (LE), power efficiency (PE), and external quantum efficiency (EQE) of OLEDs with AZO/WOx anodes were 62%, 100%, and 85% better than ITO. OLEDs with AZO/VOx anodes exhibited 62%, 75%, and 85% better LE, PE, and EQE, than ITO, respectively. The enhanced performance is ascribed to improved hole injection, charge balance, and radiative recombination efficiency. Thus, the results describe two physical mechanisms by which the workfunction of inexpensive alternatives to ITO can be tuned to yield comparable or enhanced performance.

  9. Coupled thermal-fluid-mechanics analysis of twin roll casting of A7075 aluminum alloy

    Science.gov (United States)

    Lee, Yun-Soo; Kim, Hyoung-Wook; Cho, Jae-Hyung; Chun, Se-Hwan

    2017-09-01

    Better understanding of temperature distribution and roll separation force during twin roll casting of aluminum alloys is critical to successfully fabricate good quality of aluminum strips. Therefore, the simulation techniques are widely applied to understand the twin roll casting process in a comprehensive way and to reduce the experimental time and cost of trial and error. However, most of the conventional approaches are considered thermally coupled flow, or thermally coupled mechanical behaviors. In this study, a fully coupled thermal-fluid-mechanical analysis of twin roll casting of A7075 aluminum strips was carried out using the finite element method. Temperature profile, liquid fraction and metal flow of aluminum strips with different thickness were predicted. Roll separation force and roll temperatures were experimentally obtained from a pilot-scale twin roll caster, and those results were compared with model predictions. Coupling the fluid of the liquid melt to the thermal and mechanical modeling reasonably predicted roll temperature distribution and roll separation force during twin roll casting.

  10. Electricity Generation Characteristics of Energy-Harvesting System with Piezoelectric Element Using Mechanical-Acoustic Coupling

    Directory of Open Access Journals (Sweden)

    Hirotarou Tsuchiya

    2016-01-01

    Full Text Available This paper describes the electricity generation characteristics of a new energy-harvesting system with piezoelectric elements. The proposed system is composed of a rigid cylinder and thin plates at both ends. The piezoelectric elements are installed at the centers of both plates, and one side of each plate is subjected to a harmonic point force. In this system, vibration energy is converted into electrical energy via electromechanical coupling between the plate vibration and piezoelectric effect. In addition, the plate vibration excited by the point force induces a self-sustained vibration at the other plate via mechanical-acoustic coupling between the plate vibrations and an internal sound field into the cylindrical enclosure. Therefore, the electricity generation characteristics should be considered as an electromechanical-acoustic coupling problem. The characteristics are estimated theoretically and experimentally from the electric power in the electricity generation, the mechanical power supplied to the plate, and the electricity generation efficiency that is derived from the ratio of both power. In particular, the electricity generation efficiency is one of the most appropriate factors to evaluate a performance of electricity generation systems. Thus, the effect of mechanical-acoustic coupling is principally evaluated by examining the electricity generation efficiency.

  11. Manganese-Catalyzed Cross-Coupling of Aryl Halides and Grignard Reagents by a Radical Mechanism

    DEFF Research Database (Denmark)

    Antonacci, Giuseppe; Ahlburg, Andreas; Fristrup, Peter

    2017-01-01

    The substrate scope and the mechanism have been investigated for the MnCl2-catalyzed cross-coupling reaction between aryl halides and Grignard reagents. The transformation proceeds rapidly and in good yield when the aryl halide component is an aryl chloride containing a cyano or an ester group...... in the para position or a cyano group in the ortho position. A range of other substituents gave no conversion of the aryl halide or led to the formation of side products. A broader scope was observed for the Grignard reagents, where a variety of alkyl- and arylmagnesium chlorides participated in the coupling...

  12. Target duality in N= 8 superconformal mechanics and the coupling of dual pairs

    Energy Technology Data Exchange (ETDEWEB)

    Gonzales, Marcelo [Carrera de Física Universidad Autónoma Tomás Frías, Av. Del Maestro s/n, Casilla 36, Potosí (Bolivia, Plurinational State of); Khodaee, Sadi; Toppan, Francesco [TEO, CBPF Rua Dr. Xavier Sigaud 150 (Urca), Rio de Janeiro (RJ), cep 22290-180 (Brazil); Lechtenfeld, Olaf [Institut für Theoretische Physik and Riemann Center for Geometry and Physics, Leibniz Universität Hannover, Appelstraße 2, 30167 Hannover (Germany); Centre for Quantum Engineering and Space-Time Research, Leibniz Universität Hannover, Welfengarten 1, 30167 Hannover (Germany)

    2013-07-15

    We couple dual pairs of N= 8 superconformal mechanics with conical targets of dimension d and 8−d. The superconformal coupling generates an oscillator-type potential on each of the two target factors, with a frequency depending on the respective dual coordinates. In the case of the inhomogeneous (3,8,5) model, which entails a monopole background, it is necessary to add an extra supermultiplet of constants for half of the supersymmetry. The N= 4 analog, joining an inhomogeneous (1,4,3) with a (3,4,1) multiplet, is also analyzed in detail.

  13. Optomechanical coupling between a multilayer graphene mechanical resonator and a superconducting microwave cavity.

    Science.gov (United States)

    Singh, V; Bosman, S J; Schneider, B H; Blanter, Y M; Castellanos-Gomez, A; Steele, G A

    2014-10-01

    The combination of low mass density, high frequency and high quality factor, Q, of mechanical resonators made of two-dimensional crystals such as graphene make them attractive for applications in force/mass sensing and exploring the quantum regime of mechanical motion. Microwave optomechanics with superconducting cavities offers exquisite position sensitivity and enables the preparation and detection of mechanical systems in the quantum ground state. Here, we demonstrate coupling between a multilayer graphene resonator with quality factors up to 220,000 and a high-Q superconducting cavity. Using thermomechanical noise as calibration, we achieve a displacement sensitivity of 17 fm Hz(-1/2). Optomechanical coupling is demonstrated by optomechanically induced reflection and absorption of microwave photons. We observe 17 dB of mechanical microwave amplification and signatures of strong optomechanical backaction. We quantitatively extract the cooperativity C, a characterization of coupling strength, from the measurement with no free parameters and find C = 8, which is promising for the quantum regime of graphene motion.

  14. Insights into the ion-coupling mechanism in the MATE transporter NorM-VC

    Science.gov (United States)

    Krah, Alexander; Zachariae, Ulrich

    2017-08-01

    Bacteria have developed a variety of different mechanisms to defend themselves from compounds that are toxic to them, such as antibiotics. One of these defence mechanisms is the expulsion of drugs or other noxious compounds by multidrug efflux pumps. Multidrug and toxic compound extrusion (MATE) transporters are efflux pumps that extrude metabolic waste and a variety of antibiotics out of the cell, using an ion gradient as energy source. They function via an alternating-access mechanism. When ions bind in the outward facing conformation, a large conformational change to the inward facing conformation is induced, from which the ion is released and the extruded chemical compound is bound. NorM proteins, which are usually coupled to a Na+ gradient, are members of the MATE family. However, for NorM-VC from Vibrio cholerae, it has been shown that this MATE transporter is additionally coupled to protons. How H+ and Na+ binding are coupled mechanistically to enable drug antiport is not well understood. In this study, we use molecular dynamics simulations to illuminate the sequence of ion binding events that enable efflux. Understanding this antiport mechanism is important to support the development of novel compounds that specifically inhibit the functional cycle of NorM transporters.

  15. Vibroacoustic Modeling of Mechanically Coupled Structures: Artificial Spring Technique Applied to Light and Heavy Mediums

    Directory of Open Access Journals (Sweden)

    L. Cheng

    1996-01-01

    Full Text Available This article deals with the modeling of vibrating structures immersed in both light and heavy fluids, and possible applications to noise control problems and industrial vessels containing fluids. A theoretical approach, using artificial spring systems to characterize the mechanical coupling between substructures, is extended to include fluid loading. A structure consisting of a plate-ended cylindrical shell and its enclosed acoustic cavity is analyzed. After a brief description of the proposed technique, a number of numerical results are presented. The analysis addresses the following specific issues: the coupling between the plate and the shell; the coupling between the structure and the enclosure; the possibilities and difficulties regarding internal soundproofing through modifications of the joint connections; and the effects of fluid loading on the vibration of the structure.

  16. Pinning cluster synchronization in an array of coupled neural networks under event-based mechanism.

    Science.gov (United States)

    Li, Lulu; Ho, Daniel W C; Cao, Jinde; Lu, Jianquan

    2016-04-01

    Cluster synchronization is a typical collective behavior in coupled dynamical systems, where the synchronization occurs within one group, while there is no synchronization among different groups. In this paper, under event-based mechanism, pinning cluster synchronization in an array of coupled neural networks is studied. A new event-triggered sampled-data transmission strategy, where only local and event-triggering states are utilized to update the broadcasting state of each agent, is proposed to realize cluster synchronization of the coupled neural networks. Furthermore, a self-triggered pinning cluster synchronization algorithm is proposed, and a set of iterative procedures is given to compute the event-triggered time instants. Hence, this will reduce the computational load significantly. Finally, an example is given to demonstrate the effectiveness of the theoretical results. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

  17. Opto-mechanical coupling in interfaces under static and propagative conditions and its biological implications.

    Science.gov (United States)

    Shrivastava, Shamit; Schneider, Matthias F

    2013-01-01

    Fluorescent dyes are vital for studying static and dynamic patterns and pattern formation in cell biology. Emission properties of the dyes incorporated in a biological interface are known to be sensitive to their local environment. We report that the fluorescence intensity of dye molecules embedded in lipid interfaces is indeed a thermodynamic observable of the system. Opto-mechanical coupling of lipid-dye system was measured as a function of the thermodynamic state of the interface. The corresponding state diagrams quantify the thermodynamic coupling between intensity I and lateral pressure π. We further demonstrate that the coupling is conserved upon varying the temperature T. Notably, the observed opto-mechanical coupling is not limited to equilibrium conditions, but also holds for propagating pressure pulses. The non-equilibrium data show, that fluorescence is especially sensitive to dynamic changes in state such as the LE-LC phase transition. We conclude that variations in the thermodynamic state (here π and T, in general pH, membrane potential V, etc also) of lipid membranes are capable of controlling fluorescence intensity. Therefore, interfacial thermodynamic state diagrams of I should be obtained for a proper interpretation of intensity data.

  18. Opto-mechanical coupling in interfaces under static and propagative conditions and its biological implications.

    Directory of Open Access Journals (Sweden)

    Shamit Shrivastava

    Full Text Available Fluorescent dyes are vital for studying static and dynamic patterns and pattern formation in cell biology. Emission properties of the dyes incorporated in a biological interface are known to be sensitive to their local environment. We report that the fluorescence intensity of dye molecules embedded in lipid interfaces is indeed a thermodynamic observable of the system. Opto-mechanical coupling of lipid-dye system was measured as a function of the thermodynamic state of the interface. The corresponding state diagrams quantify the thermodynamic coupling between intensity I and lateral pressure π. We further demonstrate that the coupling is conserved upon varying the temperature T. Notably, the observed opto-mechanical coupling is not limited to equilibrium conditions, but also holds for propagating pressure pulses. The non-equilibrium data show, that fluorescence is especially sensitive to dynamic changes in state such as the LE-LC phase transition. We conclude that variations in the thermodynamic state (here π and T, in general pH, membrane potential V, etc also of lipid membranes are capable of controlling fluorescence intensity. Therefore, interfacial thermodynamic state diagrams of I should be obtained for a proper interpretation of intensity data.

  19. A mechanical-optical interface for 25+ Gbps VCSEL/PD fiber coupling

    Science.gov (United States)

    Schoellner, Dirk; Lutz, Sharon; Wang, Ke; Kurtz, Dan; Kerr, Terrence; Wang, Mike

    2017-02-01

    As parallel optics data rates transition from 10 Gbps to 25 Gbps and beyond, VCSELs and photodiodes (PDs) are evolving to support the higher transmission rates. In order to maintain system performance as speeds increase and tolerances become tighter, an improved method is needed to efficiently couple VCSEL/PD array optical outputs to fiber optic networks. The mechanical-optical interface (MOI) is a monolithic component with an array of collimating lenses designed for efficient coupling between the on-board active components and a detachable fiber optic connector. This paper describes the design and implementation of a next generation MOI to match high speed VCSEL/PD requirements. Improvements to an earlier design were made to accommodate a wider variety of transceiver architectures by taking into account chip driver and wire-bond clearance requirements, while also optimizing the optical design to maximize coupling performance. Monte Carlo simulation results and the sensitivity analysis used to optimize optical performance with respect to VCSEL/PD alignment and coupling requirements are presented. Empirical testing results are shown to validate the optical model and subsequent system performance; eye-diagram results of a 25 Gbps error-free link are provided across a broad operating temperature range. Environmental and mechanical testing of the component after alignment and adhesion to the circuit substrate validates part and epoxy interaction and performance.

  20. Tuning of multiple luminescence outputs and white-light emission from a single gelator molecule through an ESIPT coupled AIEE process.

    Science.gov (United States)

    Maity, Arunava; Ali, Firoj; Agarwalla, Hridesh; Anothumakkool, Bihag; Das, Amitava

    2015-02-07

    A unique example of an ESIPT coupled AIEE process, associated with a single molecule (1), is utilized for generating multiple luminescent colors (blue-green-white-yellow). The J-aggregated state of 1 forms a luminescent gel in THF and this luminescent property is retained even in the solid state.

  1. Mechanically tuned nanocomposite coating on titanium metal with integrated properties of biofilm inhibition, cell proliferation, and sustained drug delivery.

    Science.gov (United States)

    Mishra, Sandeep K; Teotia, Arun K; Kumar, Ashok; Kannan, Sanjeevi

    2017-01-01

    The clinical success of coated implants in executing biological functions inclusive of sustainable drug release and long term antibacterial activity without antibiotics is critical. To this aim, a nanohybrid of silver nanoparticles (AgNPs) cored in polyvinyl alcohol nanocapsules (Ag-PVA NCs) embedded in chitosan (CS) matrix loaded with anti-inflammatory drug naproxen was prepared. The synthesized nanohybrids that were subjected to coatings on (3-aminopropyl)triethoxysilane (APTES) treated titanium (Ti) metal exhibited dual role of excellent inhibition on biofilm formation and sustained drug release. These dual characteristics are achieved mainly based on intrinsic antibacterial property of AgNPs and differential entrapment of drug in PVA polymeric shell of AgNPs and CS matrix. The coatings also demonstrated enhanced mechanical properties with increasing inorganic filler and stress shielding on Ti metal. The biocompatibility tests involving adhesion, proliferation and differentiation of osteoblast cells demonstrated the efficacy of Ag-PVA NCs embedded in CS matrix as a suitable coating material for orthopedic applications. Copyright © 2016 Elsevier Inc. All rights reserved.

  2. Mechanical Coupling Error Suppression Technology for an Improved Decoupled Dual-Mass Micro-Gyroscope.

    Science.gov (United States)

    Yang, Bo; Wang, Xingjun; Deng, Yunpeng; Hu, Di

    2016-04-08

    This paper presents technology for the suppression of the mechanical coupling errors for an improved decoupled dual-mass micro-gyroscope (DDMG). The improved micro-gyroscope structure decreases the moment arm of the drive decoupled torque, which benefits the suppression of the non-ideal decoupled error. Quadrature correction electrodes are added to eliminate the residual quadrature error. The structure principle and the quadrature error suppression means of the DDMG are described in detail. ANSYS software is used to simulate the micro-gyroscope structure to verify the mechanical coupling error suppression effect. Compared with the former structure, simulation results demonstrate that the rotational displacements of the sense frame in the improved structure are substantially suppressed in the drive mode. The improved DDMG structure chip is fabricated by the deep dry silicon on glass (DDSOG) process. The feedback control circuits with quadrature control loops are designed to suppress the residual mechanical coupling error. Finally, the system performance of the DDMG prototype is tested. Compared with the former DDMG, the quadrature error in the improved dual-mass micro-gyroscope is decreased 9.66-fold, and the offset error is decreased 6.36-fold. Compared with the open loop sense, the feedback control circuits with quadrature control loop decrease the bias drift by 20.59-fold and the scale factor non-linearity by 2.81-fold in the ±400°/s range.

  3. A morphing approach to couple state-based peridynamics with classical continuum mechanics

    KAUST Repository

    Han, Fei

    2016-01-04

    A local/nonlocal coupling technique called the morphing method is developed to couple classical continuum mechanics with state-based peridynamics. State-based peridynamics, which enables the description of cracks that appear and propagate spontaneously, is applied to the key domain of a structure, where damage and fracture are considered to have non-negligible effects. In the rest of the structure, classical continuum mechanics is used to reduce computational costs and to simultaneously satisfy solution accuracy and boundary conditions. Both models are glued by the proposed morphing method in the transition region. The morphing method creates a balance between the stiffness tensors of classical continuum mechanics and the weighted coefficients of state-based peridynamics through the equivalent energy density of both models. Linearization of state-based peridynamics is derived by Taylor approximations based on vector operations. The discrete formulation of coupled models is also described. Two-dimensional numerical examples illustrate the validity and accuracy of the proposed technique. It is shown that the morphing method, originally developed for bond-based peridynamics, can be successfully extended to state-based peridynamics through the original developments presented here.

  4. Mechanical Coupling Error Suppression Technology for an Improved Decoupled Dual-Mass Micro-Gyroscope

    Directory of Open Access Journals (Sweden)

    Bo Yang

    2016-04-01

    Full Text Available This paper presents technology for the suppression of the mechanical coupling errors for an improved decoupled dual-mass micro-gyroscope (DDMG. The improved micro-gyroscope structure decreases the moment arm of the drive decoupled torque, which benefits the suppression of the non-ideal decoupled error. Quadrature correction electrodes are added to eliminate the residual quadrature error. The structure principle and the quadrature error suppression means of the DDMG are described in detail. ANSYS software is used to simulate the micro-gyroscope structure to verify the mechanical coupling error suppression effect. Compared with the former structure, simulation results demonstrate that the rotational displacements of the sense frame in the improved structure are substantially suppressed in the drive mode. The improved DDMG structure chip is fabricated by the deep dry silicon on glass (DDSOG process. The feedback control circuits with quadrature control loops are designed to suppress the residual mechanical coupling error. Finally, the system performance of the DDMG prototype is tested. Compared with the former DDMG, the quadrature error in the improved dual-mass micro-gyroscope is decreased 9.66-fold, and the offset error is decreased 6.36-fold. Compared with the open loop sense, the feedback control circuits with quadrature control loop decrease the bias drift by 20.59-fold and the scale factor non-linearity by 2.81-fold in the ±400°/s range.

  5. Computational implementation of the multi-mechanism deformation coupled fracture model for salt

    Energy Technology Data Exchange (ETDEWEB)

    Koteras, J.R.; Munson, D.E.

    1996-05-01

    The Multi-Mechanism Deformation (M-D) model for creep in rock salt has been used in three-dimensional computations for the Waste Isolation Pilot Plant (WIPP), a potential waste, repository. These computational studies are relied upon to make key predictions about long-term behavior of the repository. Recently, the M-D model was extended to include creep-induced damage. The extended model, the Multi-Mechanism Deformation Coupled Fracture (MDCF) model, is considerably more complicated than the M-D model and required a different technology from that of the M-D model for a computational implementation.

  6. Direct simulation of proton-coupled electron transfer reaction dynamics and mechanisms

    Science.gov (United States)

    Kretchmer, Joshua S.; Miller, Thomas F., III

    2014-03-01

    Proton-coupled electron transfer (PCET) reactions, in which both an electron and an associated proton undergo reactive transfer, play an important role in many chemical and biological systems. Due to the complexity of this class of reactions, a variety of different mechanisms fall under the umbrella of PCET. However, the physical driving forces that determine the preferred mechanism in a given system still remain poorly understood. Towards this end, we extend ring polymer molecular dynamics (RPMD), a path-integral quantum dynamics method, to enable the direct simulation and characterization of PCET reaction dynamics in both fully atomistic and system-bath models of organometallic catalysts. In addition to providing validation for the simulation method via extensive comparison with existing PCET rate theories, we analyze the RPMD trajectories to investigate the competition between the concerted and sequential reaction mechanisms for PCET, elucidating the large role of the solvent in controlling the preferred mechanism. We further employ RPMD to determine the kinetics and mechanistic features of concerted PCET reactions across different regimes of electronic and vibrational coupling, providing evidence for a new and distinct PCET reaction mechanism.

  7. A Lever Coupling Mechanism in Dual-Mass Micro-Gyroscopes for Improving the Shock Resistance along the Driving Direction

    Directory of Open Access Journals (Sweden)

    Yang Gao

    2017-04-01

    Full Text Available This paper presents the design and application of a lever coupling mechanism to improve the shock resistance of a dual-mass silicon micro-gyroscope with drive mode coupled along the driving direction without sacrificing the mechanical sensitivity. Firstly, the mechanical sensitivity and the shock response of the micro-gyroscope are theoretically analyzed. In the mechanical design, a novel lever coupling mechanism is proposed to change the modal order and to improve the frequency separation. The micro-gyroscope with the lever coupling mechanism optimizes the drive mode order, increasing the in-phase mode frequency to be much larger than the anti-phase one. Shock analysis results show that the micro-gyroscope structure with the designed lever coupling mechanism can notably reduce the magnitudes of the shock response and cut down the stress produced in the shock process compared with the traditional elastic coupled one. Simulations reveal that the shock resistance along the drive direction is greatly increased. Consequently, the lever coupling mechanism can change the gyroscope’s modal order and improve the frequency separation by structurally offering a higher stiffness difference ratio. The shock resistance along the driving direction is tremendously enhanced without loss of the mechanical sensitivity.

  8. A Lever Coupling Mechanism in Dual-Mass Micro-Gyroscopes for Improving the Shock Resistance along the Driving Direction

    Science.gov (United States)

    Gao, Yang; Li, Hongsheng; Huang, Libin; Sun, Hui

    2017-01-01

    This paper presents the design and application of a lever coupling mechanism to improve the shock resistance of a dual-mass silicon micro-gyroscope with drive mode coupled along the driving direction without sacrificing the mechanical sensitivity. Firstly, the mechanical sensitivity and the shock response of the micro-gyroscope are theoretically analyzed. In the mechanical design, a novel lever coupling mechanism is proposed to change the modal order and to improve the frequency separation. The micro-gyroscope with the lever coupling mechanism optimizes the drive mode order, increasing the in-phase mode frequency to be much larger than the anti-phase one. Shock analysis results show that the micro-gyroscope structure with the designed lever coupling mechanism can notably reduce the magnitudes of the shock response and cut down the stress produced in the shock process compared with the traditional elastic coupled one. Simulations reveal that the shock resistance along the drive direction is greatly increased. Consequently, the lever coupling mechanism can change the gyroscope’s modal order and improve the frequency separation by structurally offering a higher stiffness difference ratio. The shock resistance along the driving direction is tremendously enhanced without loss of the mechanical sensitivity. PMID:28468288

  9. Noise Spectrum of a Quantum Point Contact Coupled to a Nano-Mechanical Oscillator

    Science.gov (United States)

    Vaidya, Nikhilesh A.

    With the advance in nanotechnology, we are more interested in the "smaller worlds". One of the practical applications of this is to measure a very small displacement or the mass of a nano-mechanical object. To measure such properties, one needs a very sensitive detector. A quantum point contact (QPC) is one of the most sensitive detectors. In a QPC, electrons tunnel one by one through a tunnel junction (a "hole"). The tunnel junction in a QPC consists of a narrow constriction (nm-wide) between two conductors. To measure the properties of a nano-mechanical object (which acts as a harmonic oscillator), we couple it to a QPC. This coupling effects the electrons tunneling through the QPC junction. By measuring the transport properties of the tunneling electrons, we can infer the properties of the oscillator (i.e. the nano-mechanical object). However, this coupling introduces noise, which reduces the measurement precision. Thus, it is very important to understand this source of noise and to study how it effects the measurement process. We theoretically study the transport properties of electrons through a QPC junction, weakly coupled to a vibration mode of a nano-mechanical oscillator via both the position and the momentum of the oscillator. We study both the position and momentum based coupling. The transport properties that we study consist of the average flow of current through the junction, given by the one-time correlation of the electron tunneling event, and the current noise given by the two-time correlation of the average current, i.e., the variance. The first comprehensive experimental study of the noise spectrum of a detector coupled to a QPC was performed by the group of Stettenheim et al. Their observed spectral features had two pronounced peaks which depict the noise produced due to the coupling of the QPC with the oscillator and in turn provide evidence of the induced feedback loop (back-action). Benatov and Blencowe theoretically studied these spectral

  10. Experimental evidence for chemo-mechanical coupling during carbon mineralization in ultramafic rocks

    Science.gov (United States)

    Lisabeth, H. P.; Zhu, W.; Kelemen, P. B.; Ilgen, A.

    2017-09-01

    Storing carbon dioxide in the subsurface as carbonate minerals has the benefit of long-term stability and immobility. Ultramafic rock formations have been suggested as a potential reservoir for this type of storage due to the availability of cations to react with dissolved carbon dioxide and the fast reaction rates associated with minerals common in ultramafic formations; however, the rapid reactions have the potential to couple with the mechanical and hydraulic behavior of the rocks and little is known about the extent and mechanisms of this coupling. In this study, we argue that the dissolution of primary minerals and the precipitation of secondary minerals along pre-existing fractures in samples lead to reductions in both the apparent Young's modulus and shear strength of aggregates, accompanied by reduction in permeability. Hydrostatic and triaxial deformation experiments were run on dunite samples saturated with de-ionized water and carbon dioxide-rich solutions while stress, strain, permeability and pore fluid chemistry were monitored. Sample microstructures were examined after reaction and deformation using scanning electron microscopy (SEM). The results show that channelized dissolution and carbonate mineral precipitation in the samples saturated with carbon dioxide-rich solutions modify the structure of grain boundaries, leading to the observed reductions in stiffness, strength and permeability. A geochemical model was run to help interpret fluid chemical data, and we find that the apparent reaction rates in our experiments are faster than rates calculated from powder reactors, suggesting mechanically enhanced reaction rates. In conclusion, we find that chemo-mechanical coupling during carbon mineralization in dunites leads to substantial modification of mechanical and hydraulic behavior that needs to be accounted for in future modeling efforts of in situ carbon mineralization projects.

  11. Sharpened cortical tuning and enhanced cortico-cortical communication contribute to the long-term neural mechanisms of visual motion perceptual learning.

    Science.gov (United States)

    Chen, Nihong; Bi, Taiyong; Zhou, Tiangang; Li, Sheng; Liu, Zili; Fang, Fang

    2015-07-15

    Much has been debated about whether the neural plasticity mediating perceptual learning takes place at the sensory or decision-making stage in the brain. To investigate this, we trained human subjects in a visual motion direction discrimination task. Behavioral performance and BOLD signals were measured before, immediately after, and two weeks after training. Parallel to subjects' long-lasting behavioral improvement, the neural selectivity in V3A and the effective connectivity from V3A to IPS (intraparietal sulcus, a motion decision-making area) exhibited a persistent increase for the trained direction. Moreover, the improvement was well explained by a linear combination of the selectivity and connectivity increases. These findings suggest that the long-term neural mechanisms of motion perceptual learning are implemented by sharpening cortical tuning to trained stimuli at the sensory processing stage, as well as by optimizing the connections between sensory and decision-making areas in the brain. Copyright © 2015 Elsevier Inc. All rights reserved.

  12. A numerical model of hydro-thermo-mechanical coupling in a fractured rock mass

    Energy Technology Data Exchange (ETDEWEB)

    Bower, Kathleen Marie [Univ. of New Mexico, Albuquerque, NM (United States)

    1996-06-01

    Coupled hydro-thermo-mechanical codes with the ability to model fractured materials are used for predicting groundwater flow behavior in fractured aquifers containing thermal sources. The potential applications of such a code include the analysis of groundwater behavior within a geothermal reservoir. The capability of modeling hydro-thermo systems with a dual porosity, fracture flow model has been previously developed in the finite element code, FEHM. FEHM has been modified to include stress coupling with the dual porosity feature. FEHM has been further developed to implicitly couple the dependence of fracture hydraulic conductivity on effective stress within two dimensional, saturated aquifers containing fracture systems. The cubic law for flow between parallel plates was used to model fracture permeability. The Bartin-Bandis relationship was used to determine the fracture aperture within the cubic law. The code used a Newton Raphson iteration to implicitly solve for six unknowns at each node. Results from a model of heat flow from a reservoir to the moving fluid in a single fracture compared well with analytic results. Results of a model showing the increase in fracture flow due to a single fracture opening under fluid pressure compared well with analytic results. A hot dry rock, geothermal reservoir was modeled with realistic time steps indicating that the modified FEHM code does successfully model coupled flow problems with no convergence problems.

  13. Modeling of magnetoelastic nanostructures with a fully coupled mechanical-micromagnetic model

    Science.gov (United States)

    Liang, Cheng-Yen; Keller, Scott M.; Sepulveda, Abdon E.; Bur, Alexandre; Sun, Wei-Yang; Wetzlar, Kyle; Carman, Gregory P.

    2014-10-01

    Micromagnetic simulations of magnetoelastic nanostructures traditionally rely on either the Stoner-Wohlfarth model or the Landau-Lifshitz-Gilbert (LLG) model, assuming uniform strain (and/or assuming uniform magnetization). While the uniform strain assumption is reasonable when modeling magnetoelastic thin films, this constant strain approach becomes increasingly inaccurate for smaller in-plane nanoscale structures. This paper presents analytical work intended to significantly improve the simulation of finite structures by fully coupling the LLG model with elastodynamics, i.e., the partial differential equations are intrinsically coupled. The coupled equations developed in this manuscript, along with the Stoner-Wohlfarth model and the LLG (constant strain) model are compared to experimental data on nickel nanostructures. The nickel nanostructures are 100 × 300 × 35 nm single domain elements that are fabricated on a Si/SiO2 substrate; these nanostructures are mechanically strained when they experience an applied magnetic field, which is used to generate M vs H curves. Results reveal that this paper’s fully-coupled approach corresponds the best with the experimental data on coercive field changes. This more sophisticated modeling technique is critical for guiding the design process of future nanoscale strain-mediated multiferroic elements, such as those needed in memory systems.

  14. Mechanisms of nonequilibrium electron-phonon coupling and thermal conductance at interfaces

    Science.gov (United States)

    Giri, Ashutosh; Gaskins, John T.; Donovan, Brian F.; Szwejkowski, Chester; Warzoha, Ronald J.; Rodriguez, Mark A.; Ihlefeld, Jon; Hopkins, Patrick E.

    2015-03-01

    We study the electron and phonon thermal coupling mechanisms at interfaces between gold films with and without Ti adhesion layers on various substrates via pump-probe time-domain thermoreflectance. The coupling between the electronic and the vibrational states is increased by more than a factor of five with the inclusion of an ˜3 nm Ti adhesion layer between the Au film and the non-metal substrate. Furthermore, we show an increase in the rate of relaxation of the electron system with increasing electron and lattice temperatures induced by the laser power and attribute this to enhanced electron-electron scattering, a transport channel that becomes more pronounced with increased electron temperatures. The inclusion of the Ti layer also results in a linear dependence of the electron-phonon relaxation rate with temperature, which we attribute to the coupling of electrons at and near the Ti/substrate interface. This enhanced electron-phonon coupling due to electron-interface scattering is shown to have negligible influence on the Kapitza conductances between the Au/Ti and the substrates at longer time scales when the electrons and phonons in the metal have equilibrated. These results suggest that only during highly nonequilibrium conditions between the electrons and phonons (Te ≫ Tp) does electron-phonon scattering at an interface contribute to thermal boundary conductance.

  15. Mechanisms of nonequilibrium electron-phonon coupling and thermal conductance at interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Giri, Ashutosh; Gaskins, John T.; Donovan, Brian F.; Szwejkowski, Chester; Hopkins, Patrick E., E-mail: phopkins@virginia.edu [Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, Virginia 22904 (United States); Warzoha, Ronald J. [Department of Mechanical Engineering, United States Naval Academy, Annapolis, Maryland 21401 (United States); Rodriguez, Mark A.; Ihlefeld, Jon [Sandia National Laboratories, Albuquerque, New Mexico 87123 (United States)

    2015-03-14

    We study the electron and phonon thermal coupling mechanisms at interfaces between gold films with and without Ti adhesion layers on various substrates via pump-probe time-domain thermoreflectance. The coupling between the electronic and the vibrational states is increased by more than a factor of five with the inclusion of an ∼3 nm Ti adhesion layer between the Au film and the non-metal substrate. Furthermore, we show an increase in the rate of relaxation of the electron system with increasing electron and lattice temperatures induced by the laser power and attribute this to enhanced electron-electron scattering, a transport channel that becomes more pronounced with increased electron temperatures. The inclusion of the Ti layer also results in a linear dependence of the electron-phonon relaxation rate with temperature, which we attribute to the coupling of electrons at and near the Ti/substrate interface. This enhanced electron-phonon coupling due to electron-interface scattering is shown to have negligible influence on the Kapitza conductances between the Au/Ti and the substrates at longer time scales when the electrons and phonons in the metal have equilibrated. These results suggest that only during highly nonequilibrium conditions between the electrons and phonons (T{sub e} ≫ T{sub p}) does electron-phonon scattering at an interface contribute to thermal boundary conductance.

  16. Novel coupled-cavity sensing mechanism for on-chip detection of microparticles (Conference Presentation)

    Science.gov (United States)

    Gillgrass, Sara-Jayne; Thomas, Robert; Smowton, Peter M.

    2017-02-01

    Coupled-cavity lasers have attracted wide attention in the past, in particular for telecommunication applications where their wavelength tunability and ability for side mode suppression are desirable. The inherent sensitivity of these devices to changes in the optical coupling has also led to their proposed use in optical sensing systems. Small changes to the refractive index of the coupler section can lead to shifts in the resonance frequency of the laser. Here we present an alternative approach to coupled-cavity sensing that exploits changes to the imaginary part of the refractive index of the coupler. An optical loss, introduced to the cavity by the passage of micro-particles, influences the optical loss of the lasing mode and changes the threshold gain requirement of the laser. The sub-linear nature of the gain-current density characteristics of the quantum confined gain medium amplifies this effect, producing an even larger perturbation in output power. We demonstrate this sensing mechanism using a monolithic coupled-cavity particle detector with on-chip capillary fill microfluidics and an in-line photo-detector section for photo-voltage transduction. Both laser and detector are pulsed allowing for a time-resolved measurement to be taken.

  17. An Investigation on the Coupled Thermal-Mechanical-Electrical Response of Automobile Thermoelectric Materials and Devices

    Science.gov (United States)

    Chen, Gang; Mu, Yu; Zhai, Pengcheng; Li, Guodong; Zhang, Qingjie

    2013-07-01

    Thermoelectric (TE) materials, which can directly convert heat to electrical energy, possess wide application potential for power generation from waste heat. As TE devices in vehicle exhaust power generation systems work in the long term in a service environment with coupled thermal-mechanical-electrical conditions, the reliability of their mechanical strength and conversion efficiency is an important issue for their commercial application. Based on semiconductor TE devices wih multiple p- n couples and the working environment of a vehicle exhaust power generation system, the service conditions of the TE devices are simulated by using the finite-element method. The working temperature on the hot side is set according to experimental measurements, and two cooling methods, i.e., an independent and shared water tank, are adopted on the cold side. The conversion efficiency and thermal stresses of the TE devices are calculated and discussed. Numerical results are obtained, and the mechanism of the influence on the conversion efficiency and mechanical properties of the TE materials is revealed, aiming to provide theoretical guidance for optimization of the design and commercial application of vehicle TE devices.

  18. The mechanism of coupling between oxido-reduction and proton translocation in respiratory chain enzymes.

    Science.gov (United States)

    Papa, Sergio; Capitanio, Giuseppe; Papa, Francesco

    2017-06-21

    The respiratory chain of mitochondria and bacteria is made up of a set of membrane-associated enzyme complexes which catalyse sequential, stepwise transfer of reducing equivalents from substrates to oxygen and convert redox energy into a transmembrane protonmotive force (PMF) by proton translocation from a negative (N) to a positive (P) aqueous phase separated by the coupling membrane. There are three basic mechanisms by which a membrane-associated redox enzyme can generate a PMF. These are membrane anisotropic arrangement of the primary redox catalysis with: (i) vectorial electron transfer by redox metal centres from the P to the N side of the membrane; (ii) hydrogen transfer by movement of quinones across the membrane, from a reduction site at the N side to an oxidation site at the P side; (iii) a different type of mechanism based on co-operative allosteric linkage between electron transfer at the metal redox centres and transmembrane electrogenic proton translocation by apoproteins. The results of advanced experimental and theoretical analyses and in particular X-ray crystallography show that these three mechanisms contribute differently to the protonmotive activity of cytochrome c oxidase, ubiquinone-cytochrome c oxidoreductase and NADH-ubiquinone oxidoreductase of the respiratory chain. This review considers the main features, recent experimental advances and still unresolved problems in the molecular/atomic mechanism of coupling between the transfer of reducing equivalents and proton translocation in these three protonmotive redox complexes. © 2017 Cambridge Philosophical Society.

  19. A Review of Low Frequency Electromagnetic Wave Phenomena Related to Tropospheric-Ionospheric Coupling Mechanisms

    Science.gov (United States)

    Simoes, Fernando; Pfaff, Robert; Berthelier, Jean-Jacques; Klenzing, Jeffrey

    2012-01-01

    Investigation of coupling mechanisms between the troposphere and the ionosphere requires a multidisciplinary approach involving several branches of atmospheric sciences, from meteorology, atmospheric chemistry, and fulminology to aeronomy, plasma physics, and space weather. In this work, we review low frequency electromagnetic wave propagation in the Earth-ionosphere cavity from a troposphere-ionosphere coupling perspective. We discuss electromagnetic wave generation, propagation, and resonance phenomena, considering atmospheric, ionospheric and magnetospheric sources, from lightning and transient luminous events at low altitude to Alfven waves and particle precipitation related to solar and magnetospheric processes. We review in situ ionospheric processes as well as surface and space weather phenomena that drive troposphere-ionosphere dynamics. Effects of aerosols, water vapor distribution, thermodynamic parameters, and cloud charge separation and electrification processes on atmospheric electricity and electromagnetic waves are reviewed. We also briefly revisit ionospheric irregularities such as spread-F and explosive spread-F, sporadic-E, traveling ionospheric disturbances, Trimpi effect, and hiss and plasma turbulence. Regarding the role of the lower boundary of the cavity, we review transient surface phenomena, including seismic activity, earthquakes, volcanic processes and dust electrification. The role of surface and atmospheric gravity waves in ionospheric dynamics is also briefly addressed. We summarize analytical and numerical tools and techniques to model low frequency electromagnetic wave propagation and solving inverse problems and summarize in a final section a few challenging subjects that are important for a better understanding of tropospheric-ionospheric coupling mechanisms.

  20. Gamma activity coupled to alpha phase as a mechanism for top-down controlled gating.

    Directory of Open Access Journals (Sweden)

    Mathilde Bonnefond

    Full Text Available Coupling between neural oscillations in different frequency bands has been proposed to coordinate neural processing. In particular, gamma power coupled to alpha phase is proposed to reflect gating of information in the visual system but the existence of such a mechanism remains untested. Here, we recorded ongoing brain activity using magnetoencephalography in subjects who performed a modified Sternberg working memory task in which distractors were presented in the retention interval. During the anticipatory pre-distractor period, we show that the phase of alpha oscillations was coupled with the power of high (80-120Hz gamma band activity, i.e. gamma power consistently was lower at the trough than at the peak of the alpha cycle (9-12Hz. We further show that high alpha power was associated with weaker gamma power at the trough of the alpha cycle. This result is in line with alpha activity in sensory region implementing a mechanism of pulsed inhibition silencing neuronal firing every ~100 ms.

  1. Conservation Laws for Coupled Hydro-mechanical Processes in Unsaturated Porous Media: Theory and Implementation

    Energy Technology Data Exchange (ETDEWEB)

    Borja, R I; White, J A

    2010-02-19

    We develop conservation laws for coupled hydro-mechanical processes in unsaturated porous media using three-phase continuum mixture theory. From the first law of thermodynamics, we identify energy-conjugate variables for constitutive modeling at macroscopic scale. Energy conjugate expressions identified relate a certain measure of effective stress to the deformation of the solid matrix, the degree of saturation to the matrix suction, the pressure in each constituent phase to the corresponding intrinsic volume change of this phase, and the seepage forces to the corresponding pressure gradients. We then develop strong and weak forms of boundary-value problems relevant for 3D finite element modeling of coupled hydro-mechanical processes in unsaturated porous media. The paper highlights a 3D numerical example illustrating the advances in the solution of large-scale coupled finite element systems, as well as the challenges in developing more predictive tools satisfying the basic conservation laws and the observed constitutive responses for unsaturated porous materials.

  2. Prediction of high-frequency vibration transmission across coupled, periodic ribbed plates by incorporating tunneling mechanisms.

    Science.gov (United States)

    Yin, Jianfei; Hopkins, Carl

    2013-04-01

    Prediction of structure-borne sound transmission on built-up structures at audio frequencies is well-suited to Statistical Energy Analysis (SEA) although the inclusion of periodic ribbed plates presents challenges. This paper considers an approach using Advanced SEA (ASEA) that can incorporate tunneling mechanisms within a statistical approach. The coupled plates used for the investigation form an L-junction comprising a periodic ribbed plate with symmetric ribs and an isotropic homogeneous plate. Experimental SEA (ESEA) is carried out with input data from Finite Element Methods (FEM). This indicates that indirect coupling is significant at high frequencies where bays on the periodic ribbed plate can be treated as individual subsystems. SEA using coupling loss factors from wave theory leads to significant underestimates in the energy of the bays when the isotropic homogeneous plate is excited. This is due to the absence of tunneling mechanisms in the SEA model. In contrast, ASEA shows close agreement with FEM and laboratory measurements. The errors incurred with SEA rapidly increase as the bays become more distant from the source subsystem. ASEA provides significantly more accurate predictions by accounting for the spatial filtering that leads to non-diffuse vibration fields on these more distant bays.

  3. The nonlinear chemo-mechanic coupled dynamics of the F 1 -ATPase molecular motor.

    Science.gov (United States)

    Xu, Lizhong; Liu, Fang

    2012-03-01

    The ATP synthase consists of two opposing rotary motors, F0 and F1, coupled to each other. When the F1 motor is not coupled to the F0 motor, it can work in the direction hydrolyzing ATP, as a nanomotor called F1-ATPase. It has been reported that the stiffness of the protein varies nonlinearly with increasing load. The nonlinearity has an important effect on the rotating rate of the F1-ATPase. Here, considering the nonlinearity of the γ shaft stiffness for the F1-ATPase, a nonlinear chemo-mechanical coupled dynamic model of F1 motor is proposed. Nonlinear vibration frequencies of the γ shaft and their changes along with the system parameters are investigated. The nonlinear stochastic response of the elastic γ shaft to thermal excitation is analyzed. The results show that the stiffness nonlinearity of the γ shaft causes an increase of the vibration frequency for the F1 motor, which increases the motor's rotation rate. When the concentration of ATP is relatively high and the load torque is small, the effects of the stiffness nonlinearity on the rotating rates of the F1 motor are obvious and should be considered. These results are useful for improving calculation of the rotating rate for the F1 motor and provide insight about the stochastic wave mechanics of F1-ATPase.

  4. Modeling coupled Thermo-Hydro-Mechanical processes including plastic deformation in geological porous media

    Science.gov (United States)

    Kelkar, S.; Karra, S.; Pawar, R. J.; Zyvoloski, G.

    2012-12-01

    There has been an increasing interest in the recent years in developing computational tools for analyzing coupled thermal, hydrological and mechanical (THM) processes that occur in geological porous media. This is mainly due to their importance in applications including carbon sequestration, enhanced geothermal systems, oil and gas production from unconventional sources, degradation of Arctic permafrost, and nuclear waste isolation. Large changes in pressures, temperatures and saturation can result due to injection/withdrawal of fluids or emplaced heat sources. These can potentially lead to large changes in the fluid flow and mechanical behavior of the formation, including shear and tensile failure on pre-existing or induced fractures and the associated permeability changes. Due to this, plastic deformation and large changes in material properties such as permeability and porosity can be expected to play an important role in these processes. We describe a general purpose computational code FEHM that has been developed for the purpose of modeling coupled THM processes during multi-phase fluid flow and transport in fractured porous media. The code uses a continuum mechanics approach, based on control volume - finite element method. It is designed to address spatial scales on the order of tens of centimeters to tens of kilometers. While large deformations are important in many situations, we have adapted the small strain formulation as useful insight can be obtained in many problems of practical interest with this approach while remaining computationally manageable. Nonlinearities in the equations and the material properties are handled using a full Jacobian Newton-Raphson technique. Stress-strain relationships are assumed to follow linear elastic/plastic behavior. The code incorporates several plasticity models such as von Mises, Drucker-Prager, and also a large suite of models for coupling flow and mechanical deformation via permeability and stresses

  5. The effects of corn zein protein coupling agent on mechanical properties of flax fiber reinforced composites

    Science.gov (United States)

    Whitacre, Ryan John

    In the field of renewable materials, natural fiber composites demonstrate the capacity to be a viable structural material. When normalized by density, flax fiber mechanical properties are competitive with E-glass fibers. However, the hydrophilic nature of flax fibers reduces the interfacial bond strength with polymer thermosets, limiting composite mechanical properties. Corn zein protein was selected as a natural bio-based coupling agent because of its combination of hydrophobic and hydrophilic properties. Zein was deposited on the surface of flax, which was then processed into unidirectional composite. The mechanical properties of zein treated samples where measured and compared against commonly utilized synthetic treatments sodium hydroxide and silane which incorporate harsh chemicals. Fourier transform infrared spectroscopy, chemical analysis, and scanning electron microscopy were also used to determine analyze zein treatments. Results demonstrate the environmentally friendly zein treatment successfully increased tensile strength 8%, flexural strength 17%, and shear strength 30% compared to untreated samples.

  6. Mechanical-magnetic-electric coupled behaviors for stress-driven Terfenol-D energy harvester

    Directory of Open Access Journals (Sweden)

    Shuying Cao

    2017-05-01

    Full Text Available The stress-driven Terfernol-D energy harvester exhibits the nonlinear mechanical-magnetic-electric coupled (MMEC behaviors and the eddy current effects. To analyze and design the device, it is necessary to establish an accurate model of the device. Based on the effective magnetic field expression, the constitutive equations with eddy currents and variable coefficients, and the dynamic equations, a nonlinear dynamic MMEC model for the device is founded. Comparisons between the measured and calculated results show that the model can describe the nonlinear coupled curves of magnetization versus stress and strain versus stress under different bias fields, and can provide the reasonable data trends of piezomagnetic coefficients, Young’s modulus and relative permeability for Terfenol-D. Moreover, the calculated power results show that the model can determine the optimal bias conditions, optimal resistance, suitable proof mass, suitable slices for the maximum energy extraction of the device under broad stress amplitude and broad frequency.

  7. submitter An experimental evaluation of the fully coupled hysteretic electro-mechanical behaviour of piezoelectric actuators

    CERN Document Server

    Butcher, Mark; Giustiniani, Alessandro; Masi, Alessandro

    2016-01-01

    Piezoelectrics are the most commonly used of the multifunctional smart materials in industrial applications, because of their relatively low cost and ease of use in electric and electronic oriented applications. Nevertheless, while datasheets usually give just small signal quasi-static parameters, their full potential can only be exploited only if a full characterization is available because the maximum stroke or the higher piezo coupling coefficients are available at different electro-mechanical biases, where often small signal analysis is not valid. In this paper a method to get the quasi-static fully coupled characterization is presented. The method is tested on a commercial piezo actuator but can be extended to similar devices.

  8. Coupling Mechanism and Decoupled Suspension Control Model of a Half Car

    Directory of Open Access Journals (Sweden)

    Hailong Zhang

    2016-01-01

    Full Text Available A structure decoupling control strategy of half-car suspension is proposed to fully decouple the system into independent front and rear quarter-car suspensions in this paper. The coupling mechanism of half-car suspension is firstly revealed and formulated with coupled damping force (CDF in a linear function. Moreover, a novel dual dampers-based controllable quarter-car suspension structure is proposed to realize the independent control of pitch and vertical motions of the half car, in which a newly added controllable damper is suggested to be installed between the lower control arm and connection rod in conventional quarter-car suspension structure. The suggested damper constantly regulates the half-car pitch motion posture in a smooth and steady operation condition meantime achieving the expected completely structure decoupled control of the half-car suspension, by compensating the evolved CDF.

  9. Piezoelectric stepper motor with direct coupling mechanism to achieve high efficiency and precise control of motion.

    Science.gov (United States)

    Glazounov, A E; Wang, S; Zhang, Q M; Kim, C

    2000-01-01

    The paper describes a piezoelectric motor that combines the merits of piezoelectric materials, such as high power density generated at electromechanical resonance, and a precise control of displacement. In the motor, a standing shear wave is excited at the resonance in the piezoelectric tube, and it produces high-frequency torsional vibrations of the stator. The vibrations are converted into unidirectional rotation of a rotor by using a direct coupling mechanism between the stator and the rotor in which a clutch drives the rotor via locking it. The direct coupling makes it possible to transmit the whole power generated in the piezoelectric tube to the rotor, and thus achieve the high efficiency of the motor. It also allows combining two regimes of operation: continuous rotation and a stepwise motion within a 360 degrees interval with a high resolution of angular displacement.

  10. Fibrils connect microtubule tips with kinetochores: a mechanism to couple tubulin dynamics to chromosome motion.

    Science.gov (United States)

    McIntosh, J Richard; Grishchuk, Ekaterina L; Morphew, Mary K; Efremov, Artem K; Zhudenkov, Kirill; Volkov, Vladimir A; Cheeseman, Iain M; Desai, Arshad; Mastronarde, David N; Ataullakhanov, Fazly I

    2008-10-17

    Kinetochores of mitotic chromosomes are coupled to spindle microtubules in ways that allow the energy from tubulin dynamics to drive chromosome motion. Most kinetochore-associated microtubule ends display curving "protofilaments," strands of tubulin dimers that bend away from the microtubule axis. Both a kinetochore "plate" and an encircling, ring-shaped protein complex have been proposed to link protofilament bending to poleward chromosome motion. Here we show by electron tomography that slender fibrils connect curved protofilaments directly to the inner kinetochore. Fibril-protofilament associations correlate with a local straightening of the flared protofilaments. Theoretical analysis reveals that protofilament-fibril connections would be efficient couplers for chromosome motion, and experimental work on two very different kinetochore components suggests that filamentous proteins can couple shortening microtubules to cargo movements. These analyses define a ring-independent mechanism for harnessing microtubule dynamics directly to chromosome movement.

  11. Mechanotransduction in mechanically coupled pulsating cells: transition to collective constriction and mesoderm invagination simulation

    Science.gov (United States)

    Driquez, Benjamin; Bouclet, Adrien; Farge, Emmanuel

    2011-12-01

    Embryonic differentiation and morphogenesis require the coordination of the cascades of gene product expression with the morphogenetic sequence of development. The influence of mechanical deformations driven by morphogenetic movements on biochemical activities was recently revealed by the existence of mechanotransduction processes in development, involving both gene transcription and protein behaviour. In the early Drosophila embryo, apical stabilization of Myosin-II leading to mesoderm invagination at the onset of gastrulation was proposed to be triggered in response to the activation of the Fog mechanotransduction pathway by the Snail-dependent active mechanical oscillations of cell apex sizes. Here we simulate the mesoderm as mechanically coupled cells, with pulsatile forces of constriction at the cell level mimicking Snail-dependent active fluctuations of apexes. We define a critical apex diameter triggering active constriction that mimics the activation of the Fog mechanotransduction pathway leading to cell constriction. We find that collective movements trigger the dynamical transition to constriction predicting the experimental dynamics of mesoderm cell apex size decrease with a modulus of contractility four times higher than the passive modulus of elastic deformation of the cells. The contraction wave is activated in a pulsation frequency-dependent process, and propagates at multicellular scales through local cell-cell mechanical interactions. By reproducing the pattern of Snail and Fog gene product protein expression in a simulation of ventral cells, the model phenocopies the pattern of Myo-II apical stabilization, and the dynamic pattern of constriction that initiates along a central sub-domain of the mesoderm. We propose that multicellular mechanical collective effects couple with mechanotransduction biochemical mechanisms to trigger the transition of collective coordinated constriction, through a mechano-genetic process ensuring efficient and regular

  12. Antenna coupling--a novel mechanism of radiofrequency electrosurgery complication: practical implications.

    Science.gov (United States)

    Robinson, Thomas N; Barnes, Kelli S; Govekar, Henry R; Stiegmann, Greg V; Dunn, Christina L; McGreevy, Francis T

    2012-08-01

    (1) To determine if antenna coupling occurs in common operating room scenarios. (2) To define modifiable clinical variables that reduce the magnitude of antenna coupling. Mechanisms of electrosurgical burns where monitoring devices contact the surgical patient are unclear. Antenna coupling occurs when the "bovie" active electrode (electrically active transmitting antenna) emits energy, which is captured by a nonelectrically active wire (electrically inactive receiving antenna) in close proximity without direct contact. Monopolar radiofrequency energy was delivered to a laparoscopic instrument (electrically active transmitting antenna), whereas other nonelectrically active wires (electrically inactive receiving antenna) including electrocardiogram (EKG) lead, nonactive "bovie" pencil, and nerve electrode monitor were placed in proximity. Temperature changes of tissue placed adjacent to the electrically inactive receiving antennae were measured. Nonelectrically active wires (receiving antenna) increase tissue temperature when lying parallel to the active electrode cord: EKG pad 2.4°C ± 1.2°C (P = 0.002), "bovie" pencil tip 90°C ± 9°C (P generated by antenna coupling included the following: increasing angulation between transmitting and receiving antennae (parallel = 90°C ± 9°C; 45° angle = 53°C ± 10°C; perpendicular = 35°C ± 11°C; P generator power setting (15 W = 59°C ± 11°C; 30 W = 90°C ± 9°C; 45 W = 98°C ± 8°C; P Simple, practical measures by the surgeon, such as orienting the receiving antenna at a greater angle and with greater separation to the active electrode cord, or lowering the generator power setting reduce antenna coupling.

  13. Flexible parallel implicit modelling of coupled thermal-hydraulic-mechanical processes in fractured rocks

    Science.gov (United States)

    Cacace, Mauro; Jacquey, Antoine B.

    2017-09-01

    Theory and numerical implementation describing groundwater flow and the transport of heat and solute mass in fully saturated fractured rocks with elasto-plastic mechanical feedbacks are developed. In our formulation, fractures are considered as being of lower dimension than the hosting deformable porous rock and we consider their hydraulic and mechanical apertures as scaling parameters to ensure continuous exchange of fluid mass and energy within the fracture-solid matrix system. The coupled system of equations is implemented in a new simulator code that makes use of a Galerkin finite-element technique. The code builds on a flexible, object-oriented numerical framework (MOOSE, Multiphysics Object Oriented Simulation Environment) which provides an extensive scalable parallel and implicit coupling to solve for the multiphysics problem. The governing equations of groundwater flow, heat and mass transport, and rock deformation are solved in a weak sense (either by classical Newton-Raphson or by free Jacobian inexact Newton-Krylow schemes) on an underlying unstructured mesh. Nonlinear feedbacks among the active processes are enforced by considering evolving fluid and rock properties depending on the thermo-hydro-mechanical state of the system and the local structure, i.e. degree of connectivity, of the fracture system. A suite of applications is presented to illustrate the flexibility and capability of the new simulator to address problems of increasing complexity and occurring at different spatial (from centimetres to tens of kilometres) and temporal scales (from minutes to hundreds of years).

  14. The Dynamic Analysis of Hydropower House and Unit System in Coupled Hydraulic-mechanical-electric Factors

    Science.gov (United States)

    MA, Z. Y.; Wu, Q. Q.

    2016-11-01

    A hydraulic-mechanical-electric and structures coupled model of hydropower station system including subsystem models of the penstock, hydro-turbine model, speed governor, synchronous generator as well as grid, rotor-bearing system and powerhouse structure is established. This model is used to simulate the small fluctuation transient process of 10% load-up in the part load condition for hydropower station. Mechanical eccentric force, unbalanced magnetic pull and vortex pressure fluctuation at inlet of draft tube are considered in the numerical calculation. The interaction between hydraulic-mechanical-electric coupled factors and structural vibration properties during the small fluctuation transient process is studied. The results indicate that the speed regulation for turbine has very litter impact on the transient process of generator. In the process of small fluctuation with loading method in this paper, structure of powerhouse is greatly influenced by vortex pressure pulse in the draft tube, and the vibration of unit is excited by loads which caused by itself rotating.

  15. All-optical non-mechanical fiber-coupled sensor for liquid- and airborne sound detection.

    Science.gov (United States)

    Rohringer, Wolfgang; Preißer, Stefan; Fischer, Balthasar

    2017-04-01

    Most fiber-optic devices for pressure, strain or temperature measurements are based on measuring the mechanical deformation of the optical fiber by various techniques. While excellently suited for detecting strain, pressure or structure-borne sound, their sensitivity to liquid- and airborne sound is so far not comparable with conventional capacitive microphones or piezoelectric hydrophones. Here, we present an all-optical acoustic sensor which relies on the detection of pressure-induced changes of the optical refractive index inside a rigid, millimeter-sized, fiber-coupled Fabry-Pérot interferometer (FPI). No mechanically movable or deformable parts take part in the signal transduction chain. Therefore, due to the absence of mechanical resonances, this sensing principle allows for high sensitivity as well as a flat frequency response over an extraordinary measurement bandwidth. As a fiber-coupled device, it can be integrated easily into already available distributed fiber-optic networks for geophysical sensing. We present characterization measurements demonstrating the sensitivity, frequency response and directivity of the device for sound and ultrasound detection in air and water. We show that low-frequency temperature and pressure drifts can be recorded in addition to acoustic sensing. Finally, selected application tests of the laser-based hydrophone and microphone implementation are presented.

  16. How LeuT shapes our understanding of the mechanisms of sodium-coupled neurotransmitter transporters.

    Science.gov (United States)

    Penmatsa, Aravind; Gouaux, Eric

    2014-03-01

    Neurotransmitter transporters are ion-coupled symporters that drive the uptake of neurotransmitters from neural synapses. In the past decade, the structure of a bacterial amino acid transporter, leucine transporter (LeuT), has given valuable insights into the understanding of architecture and mechanism of mammalian neurotransmitter transporters. Different conformations of LeuT, including a substrate-free state, inward-open state, and competitive and non-competitive inhibitor-bound states, have revealed a mechanistic framework for the transport and transport inhibition of neurotransmitters. The current review integrates our understanding of the mechanistic and pharmacological properties of eukaryotic neurotransmitter transporters obtained through structural snapshots of LeuT.

  17. Media as the mechanism behind structural coupling and the evolution of the mind

    DEFF Research Database (Denmark)

    Tække, Jesper

    of the becoming of the psychic self. After this becoming other media of communication, as mechanisms behind the structural coupling, through the history of evolution has made a continuous increase of complexity, on both sides of the distinction between the psychic and the social, possible. This would be too much...... to elaborate for this paper, why it in its second part focuses on the psychic system. It tries to elaborate how, not only language, but also later media, through the history of evolution, generate the contemporary self. In doing that the paper describes five media revolutions (speech, writing, printing...

  18. A novel mechanism involved in the coupling of mitochondrial biogenesis to oxidative phosphorylation

    Directory of Open Access Journals (Sweden)

    Jelena Ostojić

    2014-01-01

    Full Text Available Mitochondria are essential organelles that are central to a multitude of cellular processes, including oxidative phosphorylation (OXPHOS, which produces most of the ATP in animal cells. Thus it is important to understand not only the mechanisms and biogenesis of this energy production machinery but also how it is regulated in both physiological and pathological contexts. A recent study by Ostojić et al. [Cell Metabolism (2013 18, 567-577] has uncovered a regulatory loop by which the biogenesis of a major enzyme of the OXPHOS pathway, the respiratory complex III, is coupled to the energy producing activity of the mitochondria.

  19. Neurocognitive mechanisms of learning to read: print tuning in beginning readers related to word-reading fluency and semantics but not phonology.

    Science.gov (United States)

    Eberhard-Moscicka, Aleksandra K; Jost, Lea B; Raith, Margit; Maurer, Urs

    2015-01-01

    During reading acquisition children learn to recognize orthographic stimuli and link them to phonology and semantics. The present study investigated neurocognitive processes of learning to read after one year of schooling. We aimed to elucidate the cognitive processes underlying neural tuning for print that has been shown to play an important role for reading and dyslexia. A 128-channel EEG was recorded while 68 (Swiss-)German monolingual first grade children (mean age: 7.6) performed a one-back task with different types of letter and false-font strings. Print tuning was indexed by the N1 difference in the ERPs between German words and false-font strings, while the N1 lexicality effect was indexed by the difference between German words and pseudowords. In addition, we measured reading fluency, rapid automatized naming, phonological awareness, auditory memory span, and vocabulary. After one year of formal reading instruction N1 print tuning was clearly present at the group level, and could be detected at the individual level in almost 90% of the children. The N1 lexicality effect, however, could not be reliably found. On the cognitive level, next to word-reading fluency, vocabulary was also associated with N1 print tuning, but not measures reflecting phonological processing. These results demonstrate the presence of print tuning in the first year of reading acquisition and its development at the individual level. Moreover, individual differences in print tuning are not only related to word-reading fluency, but also to semantic knowledge, indicating that at early stages of learning to read the top-down modulation of print tuning is semantic rather than phonological in nature. © 2014 John Wiley & Sons Ltd.

  20. A New Molecular Mechanism To Engineer Protean Agonism at a G Protein-Coupled Receptor.

    Science.gov (United States)

    De Min, Anna; Matera, Carlo; Bock, Andreas; Holze, Janine; Kloeckner, Jessica; Muth, Mathias; Traenkle, Christian; De Amici, Marco; Kenakin, Terry; Holzgrabe, Ulrike; Dallanoce, Clelia; Kostenis, Evi; Mohr, Klaus; Schrage, Ramona

    2017-04-01

    Protean agonists are of great pharmacological interest as their behavior may change in magnitude and direction depending on the constitutive activity of a receptor. Yet, this intriguing phenomenon has been poorly described and understood, due to the lack of stable experimental systems and design strategies. In this study, we overcome both limitations: First, we demonstrate that modulation of the ionic strength in a defined experimental set-up allows for analysis of G protein-coupled receptor activation in the absence and presence of a specific amount of spontaneous receptor activity using the muscarinic M2 acetylcholine receptor as a model. Second, we employ this assay system to show that a dualsteric design principle, that is, molecular probes, carrying two pharmacophores to simultaneously adopt orthosteric and allosteric topography within a G protein-coupled receptor, may represent a novel approach to achieve protean agonism. We pinpoint three molecular requirements within dualsteric compounds that elicit protean agonism at the muscarinic M2 acetylcholine receptor. Using radioligand-binding and functional assays, we posit that dynamic ligand binding may be the mechanism underlying protean agonism of dualsteric ligands. Our findings provide both new mechanistic insights into the still enigmatic phenomenon of protean agonism and a rationale for the design of such compounds for a G protein-coupled receptor. Copyright © 2017 by The American Society for Pharmacology and Experimental Therapeutics.

  1. Coupled binding mechanism of three sodium ions and aspartate in the glutamate transporter homologue GltTk

    NARCIS (Netherlands)

    Guskov, Albert; Jensen, Sonja; Faustino, Ignacio; Marrink, Siewert J.; Slotboom, Dirk Jan

    2016-01-01

    Glutamate transporters catalyse the thermodynamically unfavourable transport of anionic amino acids across the cell membrane by coupling it to the downhill transport of cations. This coupling mechanism is still poorly understood, in part because the available crystal structures of these transporters

  2. Simultaneously Coupled Mechanical-Electrochemical-Thermal Simulation of Lithium-Ion Cells: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Chao; Santhanagopalan, Shriram; Sprague, Michael A.; Pesaran, Ahmad A.

    2016-08-01

    Understanding the combined electrochemical-thermal and mechanical response of a system has a variety of applications, for example, structural failure from electrochemical fatigue and the potential induced changes of material properties. For lithium-ion batteries, there is an added concern over the safety of the system in the event of mechanical failure of the cell components. In this work, we present a generic multi-scale simultaneously coupled mechanical-electrochemical-thermal model to examine the interaction between mechanical failure and electrochemical-thermal responses. We treat the battery cell as a homogeneous material while locally we explicitly solve for the mechanical response of individual components using a homogenization model and the electrochemical-thermal responses using an electrochemical model for the battery. A benchmark problem is established to demonstrate the proposed modeling framework. The model shows the capability to capture the gradual evolution of cell electrochemical-thermal responses, and predicts the variation of those responses under different short-circuit conditions.

  3. A coupled model between hydrogen diffusion and mechanical behavior of superelastic NiTi alloys

    Science.gov (United States)

    Elkhal Letaief, W.; Hassine, T.; Gamaoun, F.

    2017-07-01

    The undesirable effects of hydrogen show significant alterations to the thermomechanical behavior of superelastic NiTi shape memory alloys. Through experimental results, the presence of hydrogen induces a delay of forward transformation. Added to that, hydrogen-induced expansion is clearly noticed. We also remark a loss of superelasticity. These effects occur according to the hydrogen absorption by the NiTi alloy. The aim of this paper is to develop a coupled diffusion-mechanical model of shape memory alloys, which regards the aforesaid effects of hydrogen on the thermomechanical behavior and the transformation mechanism of NiTi alloys. The model is derived from the relationship between the chemical potential of hydrogen and the thermodynamics laws. Furthermore, we introduce a special transformation hardening function that predicts stress-strain behavior well during the transformation plateau. The model is implemented in ABAQUS finite element analysis software through the UMAT and UMATHT subroutines. The simulation results present good concordance with the experiments.

  4. Dynamic Modeling and Control of Electromechanical Coupling for Mechanical Elastic Energy Storage System

    Directory of Open Access Journals (Sweden)

    Yang Yu

    2013-01-01

    Full Text Available The structural scheme of mechanical elastic energy storage (MEES system served by permanent magnet synchronous motor (PMSM and bidirectional converters is designed. The aim of the research is to model and control the complex electromechanical system. The mechanical device of the complex system is considered as a node in generalized coordinate system, the terse nonlinear dynamic model of electromechanical coupling for the electromechanical system is constructed through Lagrange-Maxwell energy method, and the detailed deduction of the mathematical model is presented in the paper. The theory of direct feedback linearization (DFL is applied to decouple the nonlinear dynamic model and convert the developed model from nonlinear to linear. The optimal control theory is utilized to accomplish speed tracking control for the linearized system. The simulation results in three different cases show that the proposed nonlinear dynamic model of MEES system is correct; the designed algorithm has a better control performance in contrast with the conventional PI control.

  5. Heavy vehicle pitch dynamics and suspension tuning

    OpenAIRE

    Cao, Dongpu; Rakheja, Subhash; Su, Chun-Yi

    2008-01-01

    The influence of suspension tuning of passenger cars on bounce and pitch ride performance has been explored in a number of studies, while only minimal efforts have been made for establishing similar rules for heavy vehicles. This study aims to explore pitch dynamics and suspension tunings of a two-axle heavy vehicle with unconnected suspension, which could also provide valuable information for heavy vehicles with coupled suspensions. Based on a generalised pitch-plane model of a two-axle heav...

  6. Coupling characteristics and control of dual mechanical port machine with spoke type permanent magnet arrangement

    Science.gov (United States)

    Zhuang, Xingming; Song, Qiang; Wen, Xuhui; Zhao, Feng; Fan, Tao

    2014-11-01

    Dual mechanical port machine(DMPM), as a novel electromechanical energy conversion device, has attracted widespread attention. DMPM with spoke type permanent magnet arrangements(STPM-DMPM), which is one of several types of DMPM, has been of interest recently. The unique coupling characteristics of STPM-DMPM are beneficial to improving system performance, but these same characteristics increase the difficulties of control. Now there has been little research about the control of STPM-DMPM, and this has hindered its practical application. Based on a mathematical model of STPM-DMPM, the coupling characteristics and the merits and demerits of such devices are analyzed as applied to a hybrid system. The control strategies for improving the disadvantages and for utilizing the advantage of coupling are researched. In order to weaken the interaction effect of torque outputs in the inner motor and the outer motor that results from coupling in STPM-DMPM, a decoupling control method based on equivalent current control is proposed, and independent torque control for the inner motor and outer motor is achieved. In order to solve address the problem of adequately utilization of coupling, minimizing the overall copper loss of the inner motor and the outer motor of STPM-DMPM is taken as the optimization objective for optimal control, and the purpose of utilizing the coupling adequately and reasonably is achieved. The verification tests of the proposed decoupling control and optimal control strategies are carried out on a prototype STPM-DMPM, and the experimental results show that the interaction effect of torque outputs in the inner motor and the outer motor can be markedly weakened through use of the control method. The overall copper loss of the inner motor and the outer motor can be markedly reduced through use of the optimal control method, while the power output remains unchanged. A breakthrough in the control problem of STPM-DMPM is accomplished by combining the control

  7. Modelling studies of possible coupling mechanisms between the upper and middle atmosphere

    Science.gov (United States)

    Dobbin, Alison Louise

    In recent years, the evidence for a correlation between lower atmospheric behaviour and changes in solar activity has increased. This correlation is thought to be associated with complex coupling mechanisms that link the upper and lower regions of the atmosphere. Dynamical processes are believed to play an important role via the influence of large- and small-scale waves that can lead to the transport of energy, momentum and chemical constituents. Compositional and energetic changes that occur as a direct result of changes in solar energy flux are also thought to contribute to the coupling of atmospheric regions. The production and transport of odd nitrogen species is thought to be particularly important, especially following periods of enhanced geomagnetic activity. The UCL Coupled Middle Atmosphere - Thermosphere (CMAT) general circulation model was developed in order to provide a tool to investigate two-way coupling between the Earth's lower and upper atmosphere. This model has been updated to include high-resolution empirical solar flux data and current photoabsorption and ionisation cross sections. Improvements have been made to the chemical scheme, and a new spectral gravity wave parameterisation has been implemented Factors influencing production and loss of odd nitrogen species in the lower thermosphere have been investigated. The representation of nitric oxide in the CMAT model is presented and compared with empirical data. Studies have been carried out to investigate the global production, transport and impact of nitric oxide in the MLT (mesosphere lower thermosphere) region during and following periods of enhanced solar and geomagnetic activity, including a simulation of the 2003 'Halloween super storm'. The effect of the new gravity wave parameterisation on the zonal and meridional wind structure is also investigated along with its effect on the equatorial local diurnal maximum of atomic oxygen and associated OS) 557.7nm green line volume emission rates.

  8. Simultaneous cooling of coupled mechanical oscillators using whispering gallery mode resonances.

    Science.gov (United States)

    Li, Ying Lia; Millen, James; Barker, P F

    2016-01-25

    We demonstrate simultaneous center-of-mass cooling of two coupled oscillators, consisting of a microsphere-cantilever and a tapered optical fiber. Excitation of a whispering gallery mode (WGM) of the microsphere, via the evanescent field of the taper, provides a transduction signal that continuously monitors the relative motion between these two microgram objects with a sensitivity of 3 pm. The cavity enhanced optical dipole force is used to provide feedback damping on the motion of the micron-diameter taper, whereas a piezo stack is used to damp the motion of the much larger (up to 180 μm in diameter), heavier (up to 1.5 × 10(-7) kg) and stiffer microsphere-cantilever. In each feedback scheme multiple mechanical modes of each oscillator can be cooled, and mode temperatures below 10 K are reached for the dominant mode, consistent with limits determined by the measurement noise of our system. This represents stabilization on the picometer level and is the first demonstration of using WGM resonances to cool the mechanical modes of both the WGM resonator and its coupling waveguide.

  9. Mobility power flow analysis of coupled plate structure subjected to mechanical and acoustic excitation

    Science.gov (United States)

    Cuschieri, J. M.

    1992-01-01

    The mobility power flow approach that was previously applied in the derivation of expressions for the vibrational power flow between coupled plate substructures forming an L configuration and subjected to mechanical loading is generalized. Using the generalized expressions, both point and distributed mechanical loads on one or both of the plates can be considered. The generalized approach is extended to deal with acoustic excitation of one of the plate substructures. In this case, the forces (acoustic pressures) acting on the structure are dependent on the response of the structure because of the scattered pressure component. The interaction between the plate structure and the acoustic fluid leads to the derivation of a corrected mode shape for the plates' normal surface velocity and also for the structure mobility functions. The determination of the scattered pressure components in the expressions for the power flow represents an additional component in the power flow balance for the source plate and the receiver plate. This component represents the radiated acoustical power from the plate structure. For a number of coupled plate substrates, the acoustic pressure generated by one substructure will interact with the motion of another substructure. That is, in the case of the L-shaped plate, acoustic interaction exists between the two plate substructures due to the generation of the acoustic waves by each of the substructures. An approach to deal with this phenomena is described.

  10. Finite Element Analysis of Mechanical Characteristics of Dropped Eggs Based on Fluid-Solid Coupling Theory

    Directory of Open Access Journals (Sweden)

    Song Haiyan

    2017-01-01

    Full Text Available It is important to study the properties and mechanics of egg drop impacts in order to reduce egg loss during processing and logistics and to provide a basis for the protective packaging of egg products. In this paper, we present the results of our study of the effects of the structural parameters on the mechanical properties of an egg using a finite element model of the egg. Based on Fluid-Solid coupling theory, a finite element model of an egg was constructed using ADINA, a finite element calculation and analysis software package. To simplify the model, the internal fluid of the egg was considered to be a homogeneous substance. The egg drop impact was simulated by the coupling solution, and the feasibility of the model was verified by comparison with the experimental results of a drop test. In summary, the modeling scheme was shown to be feasible and the simulation results provide a theoretical basis for the optimum design of egg packaging and egg processing equipment.

  11. Swarming populations of Salmonella represent a unique physiological state coupled to multiple mechanisms of antibiotic resistance

    Directory of Open Access Journals (Sweden)

    Kim Wook

    2003-01-01

    Full Text Available Salmonella enterica serovar Typhimurium is capable of swarming over semi-solid surfaces. Although its swarming behavior shares many readily observable similarities with other swarming bacteria, the phenomenon remains somewhat of an enigma in this bacterium since some attributes skew away from the better characterized systems. Swarming is quite distinct from the classic swimming motility, as there is a prerequisite for cells to first undergo a morphological transformation into swarmer cells. In some organisms, swarming is controlled by quorum sensing, and in others, swarming has been shown to be coupled to increased expression of important virulence factors. Swarming in serovar Typhimurium is coupled to elevated resistance to a wide variety of structurally and functionally distinct classes of antimicrobial compounds. As serovar Typhimurium differentiates into swarm cells, the pmrHFIJKLM operon is up-regulated, resulting in a more positively charged LPS core. Furthermore, as swarm cells begin to de-differentiate, the pmr operon expression is down-regulated, rapidly reaching the levels observed in swim cells. This is one potential mechanism which confers swarm cells increased resistance to antibiotics such as the cationic antimicrobial peptides. However, additional mechanisms are likely associated with the cells in the swarm state that confer elevated resistance to such a broad spectrum of antimicrobial agents.

  12. Manufacture of dissolving pulps from cornstalk by novel method coupling steam explosion and mechanical carding fractionation.

    Science.gov (United States)

    Wang, Ning; Chen, Hong-Zhang

    2013-07-01

    In order to solve the inhomogeneity of cornstalk as fiber material to manufacture dissolving pulp, a novel method of steam explosion coupling mechanical carding was put forward to fractionate cornstalk long fiber for the production of cornstalk dissolving pulp. The fractionated long fiber had homogeneous structure and low hemicellulose and ash content. The fiber cell content was up to 85% in area, and the hemicellulose and ash content was 8.34% and 1.10% respectively. The α-cellulose content of cornstalk dissolving pulps was up to 93.10-97.10%, the viscosity was 14.37-23.96 mPas, and the yields of cornstalk dissolving pulps were from 10.11% to 12.44%. In addition, the fractionated short fiber was to be hydrolyzed by enzyme to build sugar platform. The constructed method of steam explosion coupling mechanical carding achieved the fractionation of cornstalk into long fiber and short fiber cleanly and effectively, and provided a new way for cornstalk integrated refinery. Copyright © 2013 Elsevier Ltd. All rights reserved.

  13. Failure mechanism and coupled static-dynamic loading theory in deep hard rock mining: A review

    Directory of Open Access Journals (Sweden)

    Xibing Li

    2017-08-01

    Full Text Available Rock failure phenomena, such as rockburst, slabbing (or spalling and zonal disintegration, related to deep underground excavation of hard rocks are frequently reported and pose a great threat to deep mining. Currently, the explanation for these failure phenomena using existing dynamic or static rock mechanics theory is not straightforward. In this study, new theory and testing method for deep underground rock mass under coupled static-dynamic loading are introduced. Two types of coupled loading modes, i.e. “critical static stress + slight disturbance” and “elastic static stress + impact disturbance”, are proposed, and associated test devices are developed. Rockburst phenomena of hard rocks under coupled static-dynamic loading are successfully reproduced in the laboratory, and the rockburst mechanism and related criteria are demonstrated. The results of true triaxial unloading compression tests on granite and red sandstone indicate that the unloading can induce slabbing when the confining pressure exceeds a certain threshold, and the slabbing failure strength is lower than the shear failure strength according to the conventional Mohr-Column criterion. Numerical results indicate that the rock unloading failure response under different in situ stresses and unloading rates can be characterized by an equivalent strain energy density. In addition, we present a new microseismic source location method without premeasuring the sound wave velocity in rock mass, which can efficiently and accurately locate the rock failure in hard rock mines. Also, a new idea for deep hard rock mining using a non-explosive continuous mining method is briefly introduced.

  14. Simulation of Weld Mechanical Behavior to Include Welding-Induced Residual Stress and Distortion: Coupling of SYSWELD and Abaqus Codes

    Science.gov (United States)

    2015-11-01

    2011, Vol. 88, pg. 45-56. 7. Z.H. Guo, X.Y. Ou, G.W. Shuai, and Y.H. Chen, Numerical Simulation of Temperature Field for TIG Welding of Aluminum Alloy...Memorandum Simulation of Weld Mechanical Behavior to Include Welding -Induced Residual Stress and Distortion: Coupling of SYSWELD and Abaqus Codes... Weld Mechanical Behavior to Include Welding -Induced Residual Stress and Distortion: Coupling of SYSWELD and Abaqus Codes by Charles R. Fisher

  15. Simulation of Weld Mechanical Behavior to Include Welding Induced Residual Stress and Distortion: Coupling of SYSWELD and Abaqus Codes

    Science.gov (United States)

    2015-11-01

    2011, Vol. 88, pg. 45-56. 7. Z.H. Guo, X.Y. Ou, G.W. Shuai, and Y.H. Chen, Numerical Simulation of Temperature Field for TIG Welding of Aluminum Alloy...Memorandum Simulation of Weld Mechanical Behavior to Include Welding -Induced Residual Stress and Distortion: Coupling of SYSWELD and Abaqus Codes... Weld Mechanical Behavior to Include Welding -Induced Residual Stress and Distortion: Coupling of SYSWELD and Abaqus Codes by Charles R. Fisher

  16. Coupled chemo-electro-mechanical simulation of polyelectrolyte gels as actuators and sensors

    Science.gov (United States)

    Wallmersperger, Thomas; Ballhause, Dirk; Kröplin, Bernd; Günther, Margarita; Shi, Zhangman; Gerlach, Gerald

    2008-03-01

    Polyelectrolyte gels are ductile elastic electroactive materials. They consist of a polymer network with charged groups and a liquid phase with mobile ions. Changing the chemical or electric conditions in the gel-surrounding solution leads to a change of the chemo-electro-mechanical state in the gel phase: diffusion and migration of ions and solvent between the gel and solution phases trigger the swelling or shrinkage of the polymer gel. In case of chemical stimulation (change of pH or salt concentration), a swelling ratio of up to 100% may be obtained. Due to this large swelling ratio the gels exhibit excellent actuatoric capabilities. In this paper, a polyelectrolyte gel placed in a solution bath is investigated. The actuatoric and sensoric capabilities are described by a chemo-electro-mechanical model. The chemical field is represented by a convection-migration-diffusion equation while the electric field is described by a quasi-static Laplace equation. For the mechanical field a partial differential equation of first order in time is applied. Inertia effects are neglected due to the relatively slow swelling/shrinkage process. On the one hand, the coupling between the chemo-electrical and the mechanical field is realised by the differential osmotic pressure stemming from the concentration differences between gel and solution. On the other hand, the mechanical deformation influences the concentration of the bound charged groups in the gel. The three fields are solved simultaneously by applying the Newton Raphson method using finite elements in space and finite differences in time. The developed model is applicable for both, hydrogel actuators and sensors. Numerical results of swelling and bending are given for chemically and electrically stimulated polymer gels. In this paper we show the differences between the chemo-electric and the fully coupled chemo-electro-mechanical formulation for polymer gels in different solution baths. The inverse (sensor-) effect is

  17. Coupled rolling motion: a student project in non-holonomic mechanics

    Science.gov (United States)

    Janová, Jitka; Musilová, Jana; Bartoš, Jiří

    2009-11-01

    This paper presents an original undergraduate student project in theoretical mechanics: a demonstration of theory and experiment agreement inspired by a recently theoretically treated mechanical problem of coupled rolling motion of two cylinders. The problem of a mechanical system subjected to non-holonomic constraints is theoretically and numerically solved. Subsequently, the solution is quantitatively verified by a simple and inexpensive experiment, originally proposed and constructed by the authors. The comparison of results of the theoretical study with experimental output shows that there are instruments to directly verify rather abstract mathematical theories even on the undergraduate level. Moreover, combining the theoretical description of the problem with an appropriate laboratory experiment and computational procedures gives students a more complex view of the physical problem as a whole. This paper can be used by physics teachers on the undergraduate university level as an inspiration for an interesting student project. Moreover, the theoretical part of this paper itself can be used by interested intermediate students themselves as a good exercise in theoretical mechanics.

  18. Wellbore Stability in Oil and Gas Drilling with Chemical-Mechanical Coupling

    Directory of Open Access Journals (Sweden)

    Chuanliang Yan

    2013-01-01

    Full Text Available Wellbore instability in oil and gas drilling is resulted from both mechanical and chemical factors. Hydration is produced in shale formation owing to the influence of the chemical property of drilling fluid. A new experimental method to measure diffusion coefficient of shale hydration is given, and the calculation method of experimental results is introduced. The diffusion coefficient of shale hydration is measured with the downhole temperature and pressure condition, then the penetration migrate law of drilling fluid filtrate around the wellbore is calculated. Furthermore, the changing rules of shale mechanical properties affected by hydration and water absorption are studied through experiments. The relationships between shale mechanical parameters and the water content are established. The wellbore stability model chemical-mechanical coupling is obtained based on the experimental results. Under the action of drilling fluid, hydration makes the shale formation softened and produced the swelling strain after drilling. This will lead to the collapse pressure increases after drilling. The study results provide a reference for studying hydration collapse period of shale.

  19. Modeling of excavation induced coupled hydraulic-mechanical processes in claystone

    Energy Technology Data Exchange (ETDEWEB)

    Massmann, Jobst

    2009-07-01

    Concepts for the numerical modeling of excavation induced processes in claystone are investigated. The study has been motivated by the international discussion on the adequacy of claystone as a potential host rock for a final repository of radioactive waste. The processes, which could impact the safety of such a repository, are manifold and strongly interacting. Thus, a multiphysics approach is needed, regarding solid mechanics and fluid mechanics within a geological context. A coupled modeling concept is therefore indispensable. Based on observations and measurements at an argillaceous test site (the underground laboratory Tournemire, operated by the Institute of Radioprotection and Nuclear Safety, France) the modeling concept is developed. Two main processes constitute the basis of the applied model: deformation (linear elasticity considering damage) and fluid flow (unsaturated one-phase flow). Several coupling phenomena are considered: Terzaghi 's effective stress concept, mass conservation of the liquid in a deformable porous media, drying induced shrinkage, and a permeability which depends on deformation and damage. In addition, transversely isotropic material behavior is considered. The numerical simulations are done with the finite element code RockFlow, which is extended to include: an orthotropic non-linear shrinkage model, a continuum damage model, and an orthotropic permeability model. For these new methods the theory and a literature review are presented, followed by applications, which illustrate the capability to model excavation induced processes in principle. In a comprehensive case study, the modeling concept is used to simulate the response of the Tournemire argillite to excavation. The results are compared with observations and measurements of three different excavations (century old tunnel, two galleries excavated in 1996 and 2003). In summary, it can be concluded that the developed model concept provides a prediction of the excavation

  20. Propagation of SH waves in a piezoelectric/piezomagnetic plate: Effects of interfacial imperfection couplings and the related physical mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Hong-Xing [Beijing Advanced Innovation Center for Imaging Technology, Capital Normal University, Beijing 100048 (China); Li, Yong-Dong, E-mail: LYDbeijing@163.com [Beijing Advanced Innovation Center for Imaging Technology, Capital Normal University, Beijing 100048 (China); Department of Mechanical Engineering, Academy of Armored Force Engineering, Beijing 100072 (China); Xiong, Tao [Department of Mechanical Engineering, Academy of Armored Force Engineering, Beijing 100072 (China); Guan, Yong [Beijing Advanced Innovation Center for Imaging Technology, Capital Normal University, Beijing 100048 (China)

    2016-09-07

    The problem of dispersive SH wave in a piezoelectric/piezomagnetic plate that contains an imperfect interface is considered in the present work. An imperfection coupling model is adopted to describe the magnetic, electric and mechanical imperfections on the interface. A transcendental dispersion equation is derived and numerically solved to get the phase velocity. The validity of the numerical procedure is verified in a degenerated case. The effects of the coupled interfacial imperfections on the dispersion behavior of SH waves are discussed in detail and the related underlying physical mechanisms are explained. - Highlights: • SH-wave is investigated in a multiferroic plate with coupled interfacial imperfections. • SH-wave is affected by both interfacial imperfections and their inter-couplings. • Physical mechanisms of the effects are explained via energy transformations.

  1. Improvement in mechanical properties of glass fiber fabric/PVC composites with chopped glass fibers and coupling agent

    Science.gov (United States)

    Lee, Jaewoong; Park, Su Bin; Lee, Joon Seok; Kim, Jong Won

    2017-07-01

    Glass fiber reinforced polyvinylchloride (PVC) composite is used widely because of its low price, chemical resistance, and dimensional stability, but most are short fiber reinforced PVC composites. Fabric reinforced composite have undulated regions, which is the only region without fiber, due to the characteristics of the weave construction, and it limits increasing the mechanical properties. Therefore, in this study, to increase the mechanical properties, the undulated regions of the glass fiber fabric/PVC composite were filled with a silane coupling agent treated chopped fiber. The physical properties, dynamic mechanical thermal properties, and mechanical properties of the prepared composite were observed. The critical fiber aspect ratio of the chopped fiber is different for each mechanical property. This shows that the fabric-reinforced composite of chopped fibers affect each of the mechanical properties differently. In addition, the silane coupling treatment increases the compatibility of the composite components, improving the mechanical properties.

  2. Modeling the coupled mechanics, transport, and growth processes in collagen tissues.

    Energy Technology Data Exchange (ETDEWEB)

    Holdych, David J.; Nguyen, Thao D.; Klein, Patrick A.; in' t Veld, Pieter J.; Stevens, Mark Jackson

    2006-11-01

    The purpose of this project is to develop tools to model and simulate the processes of self-assembly and growth in biological systems from the molecular to the continuum length scales. The model biological system chosen for the study is the tendon fiber which is composed mainly of Type I collagen fibrils. The macroscopic processes of self-assembly and growth at the fiber scale arise from microscopic processes at the fibrillar and molecular length scales. At these nano-scopic length scales, we employed molecular modeling and simulation method to characterize the mechanical behavior and stability of the collagen triple helix and the collagen fibril. To obtain the physical parameters governing mass transport in the tendon fiber we performed direct numerical simulations of fluid flow and solute transport through an idealized fibrillar microstructure. At the continuum scale, we developed a mixture theory approach for modeling the coupled processes of mechanical deformation, transport, and species inter-conversion involved in growth. In the mixture theory approach, the microstructure of the tissue is represented by the species concentration and transport and material parameters, obtained from fibril and molecular scale calculations, while the mechanical deformation, transport, and growth processes are governed by balance laws and constitutive relations developed within a thermodynamically consistent framework.

  3. Analytical Kinematics and Coupled Vibrations Analysis of Mechanical System Operated by Solar Array Drive Assembly

    Science.gov (United States)

    Sattar, M.; Wei, C.; Jalali, A.; Sattar, R.

    2017-07-01

    To address the impact of solar array (SA) anomalies and vibrations on performance of precision space-based operations, it is important to complete its accurate jitter analysis. This work provides mathematical modelling scheme to approximate kinematics and coupled micro disturbance dynamics of rigid load supported and operated by solar array drive assembly (SADA). SADA employed in analysis provides a step wave excitation torque to activate the system. Analytical investigations into kinematics is accomplished by using generalized linear and Euler angle coordinates, applying multi-body dynamics concepts and transformations principles. Theoretical model is extended, to develop equations of motion (EoM), through energy method (Lagrange equation). The main emphasis is to research coupled frequency response by determining energies dissipated and observing dynamic behaviour of internal vibratory systems of SADA. The disturbance model captures discrete active harmonics of SADA, natural modes and vibration amplifications caused by interactions between active harmonics and structural modes of mechanical assembly. The proposed methodology can help to predict true micro disturbance nature of SADA operating rigid load. Moreover, performance outputs may be compared against actual mission requirements to assess precise spacecraft controller design to meet next space generation stringent accuracy goals.

  4. Magnetic medium broadband metamaterial absorber based on the coupling resonance mechanism

    Science.gov (United States)

    Li, Wangchang; Qiao, Xiaojing; Luo, Yang; Qin, F. X.; Peng, H. X.

    2014-04-01

    In this paper, we present a design, simulation and experimental measurement of a metamaterial absorber (MMA) in the microwave regime. The proposed MMA structure consists of periodic cross electric resonators separated from the ground metal plane using a magnetic composite layer. The broadband absorption can be ascribed to the periodic cross electric resonators. The anti-parallel currents are observed at the peak frequency on the surface of the MMA and the ground metal plane, respectively, and thus the coupled resonance magnetic field occurs in the magnetic medium resulting in the magnetic loss. The new absorption peak located at 2.8 GHz broadens the whole absorption spectrum. The frequency of this peck is lower than that of the cross resonator of 3.7 GHz, suggesting the distinguish resonance mechanism: the absorbing properties are ascribed to the phase cancellation, Ohmic loss, dielectric loss at the end of the cross pattern, and the magnetic loss caused by the above mentioned coupled magnetic field. The obvious absorption peak at 2.8 GHz is also observed experimentally verifying the simulation result. All these results indicate the proposed MMA structure is promising for microwave absorbing application.

  5. Reheating mechanism of the curvaton with nonminimal derivative coupling to gravity

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, Taotao [Central China Normal University, Institute of Astrophysics, Wuhan (China); Central China Normal University, Key Laboratory of Quark and Lepton Physics (MOE) and College of Physical Science and Technology, Wuhan (China); Feng, Kaixi [Chinese Academy of Sciences, Institute of Theoretical Physics, Beijing (China)

    2017-10-15

    In this paper, we continue our study of the curvaton model with nonminimal derivative coupling (NDC) to Einstein gravity proposed in our previous work (Feng in Phys Lett B 729:99, 2014; Feng and Qiu in Phys Rev D 90(12):123508, 2014), focusing on the reheating mechanism. We found that according to whether the curvaton has or has not dominated the background after the end of inflation, it will have two different behaviors of evolution, which should be the general property of the curvaton with nonminimal couplings. This will cause two different parts of reheating, which goes on via the parametric resonance process. The reheating temperature is estimated for both cases in which reheating completes before and after curvaton domination, and the constraints are quite loose compared to that of overproduction of gravitinos. Finally we investigated the evolution of curvature perturbation during reheating. We have shown both analytically and numerically that the curvature perturbation will not blow up during the resonance process. (orig.)

  6. Substrate-Na{sup +} complex formation: Coupling mechanism for {gamma}-aminobutyrate symporters

    Energy Technology Data Exchange (ETDEWEB)

    Pallo, Anna; Simon, Agnes [Department of Neurochemistry, Institute of Biomolecular Chemistry, Chemical Research Center, Hungarian Academy of Sciences (Hungary); Bencsura, Akos [Department of Theoretical Chemistry, Institute of Structural Chemistry, Chemical Research Center, Hungarian Academy of Sciences, Budapest (Hungary); Heja, Laszlo [Department of Neurochemistry, Institute of Biomolecular Chemistry, Chemical Research Center, Hungarian Academy of Sciences (Hungary); Kardos, Julianna, E-mail: jkardos@chemres.hu [Department of Neurochemistry, Institute of Biomolecular Chemistry, Chemical Research Center, Hungarian Academy of Sciences (Hungary)

    2009-07-24

    Crystal structures of transmembrane transport proteins belonging to the important families of neurotransmitter-sodium symporters reveal how they transport neurotransmitters across membranes. Substrate-induced structural conformations of gated neurotransmitter-sodium symporters have been in the focus of research, however, a key question concerning the mechanism of Na{sup +} ion coupling remained unanswered. Homology models of human glial transporter subtypes of the major inhibitory neurotransmitter {gamma}-aminobutyric acid were built. In accordance with selectivity data for subtype 2 vs. 3, docking and molecular dynamics calculations suggest similar orthosteric substrate (inhibitor) conformations and binding crevices but distinguishable allosteric Zn{sup 2+} ion binding motifs. Considering the occluded conformational states of glial human {gamma}-aminobutyric acid transporter subtypes, we found major semi-extended and minor ring-like conformations of zwitterionic {gamma}-aminobutyric acid in complex with Na{sup +} ion. The existence of the minor ring-like conformation of {gamma}-aminobutyric acid in complex with Na{sup +} ion may be attributed to the strengthening of the intramolecular H-bond by the electrostatic effect of Na{sup +} ion. Coupling substrate uptake into cells with the thermodynamically favorable Na{sup +} ion movement through substrate-Na{sup +} ion complex formation may be a mechanistic principle featuring transmembrane neurotransmitter-sodium symporter proteins.

  7. Altered nucleotide-microtubule coupling and increased mechanical output by a kinesin mutant.

    Directory of Open Access Journals (Sweden)

    Hong-Lei Liu

    Full Text Available Kinesin motors hydrolyze ATP to produce force and do work in the cell--how the motors do this is not fully understood, but is thought to depend on the coupling of ATP hydrolysis to microtubule binding by the motor. Transmittal of conformational changes from the microtubule- to the nucleotide-binding site has been proposed to involve the central β-sheet, which could undergo large structural changes important for force production. We show here that mutation of an invariant residue in loop L7 of the central β-sheet of the Drosophila kinesin-14 Ncd motor alters both nucleotide and microtubule binding, although the mutated residue is not present in either site. Mutants show weak-ADP/tight-microtubule binding, instead of tight-ADP/weak-microtubule binding like wild type--they hydrolyze ATP faster than wild type, move faster in motility assays, and assemble long spindles with greatly elongated poles, which are also produced by simulations of assembly with tighter microtubule binding and faster sliding. The mutated residue acts like a mechanochemical coupling element--it transmits changes between the microtubule-binding and active sites, and can switch the state of the motor, increasing mechanical output by the motor. One possibility, based on our findings, is that movements by the residue and the loop that contains it could bend or distort the central β-sheet, mediating free energy changes that lead to force production.

  8. Realistic opto-mechanical simulation and tolerancing of an automotive optical transmitter coupling system

    Science.gov (United States)

    Vervaeke, Michael; Moens, Els; Meuret, Youri; Ottevaere, Heidi; Van Buggenhout, Carl; De Pauw, Piet; Thienpont, Hugo

    2010-05-01

    The advent of Plastic Optical Fibre (POF) opened perspectives for numerous applications in the field of datacommunications. POF is increasingly popular in the automotive industry as a robust, lightweight, electromagnetic interference free, easy and cheap to install alternative to electrical wiring for high-speed entertainment, navigation and data acquisition systems in cars. The main challenge for the introduction of datacommunication systems based on POF is imposed by the working conditions of automotive applications: systems should remain fully functional in a temperature range from -40 °C to +115 °C . Furthermore, standardisation and mechanical design considerations put a number of other boundary conditions. We designed a misalignment-tolerant optical coupling system according to the Media Oriented Systems Transport standard (MOST) to convey the divergent beam from a Resonant Cavity Light Emitting Diode (RCLED) into a Step-Index (SI) multimode POF mounted in a detachable ferrule. In this contribution we describe the methodology to synthesize the dimensions and tolerances on the optical components in the coupling system. A Monte Carlo optimisation algorithm on the full three-dimensional (3D) description of the complete RCLED package and detachable POF ferrule was used to allow a realistic modelling of all misalignments that could occur in the production chain. We select the best suited system according to manufacturing and assembly capabilities as well as its suitability for automotive applications.

  9. FE Analysis of Rock with Hydraulic-Mechanical Coupling Based on Continuum Damage Evolution

    Directory of Open Access Journals (Sweden)

    Yongliang Wang

    2016-01-01

    Full Text Available A numerical finite element (FE analysis technology is presented for efficient and reliable solutions of rock with hydraulic-mechanical (HM coupling, researching the seepage characteristics and simulating the damage evolution of rock. To be in accord with the actual situation, the rock is naturally viewed as heterogeneous material, in which Young’s modulus, permeability, and strength property obey the typical Weibull distribution function. The classic Biot constitutive relation for rock as porous medium is introduced to establish a set of equations coupling with elastic solid deformation and seepage flow. The rock is subsequently developed into a novel conceptual and practical model considering the damage evolution of Young’s modulus and permeability, in which comprehensive utilization of several other auxiliary technologies, for example, the Drucker-Prager strength criterion, the statistical strength theory, and the continuum damage evolution, yields the damage variable calculating technology. To this end, an effective and reliable numerical FE analysis strategy is established. Numerical examples are given to show that the proposed method can establish heterogeneous rock model and be suitable for different load conditions and furthermore to demonstrate the effectiveness and reliability in the seepage and damage characteristics analysis for rock.

  10. New functions and signaling mechanisms for the class of adhesion G protein-coupled receptors

    DEFF Research Database (Denmark)

    Liebscher, Ines; Ackley, Brian; Araç, Demet

    2014-01-01

    The class of adhesion G protein-coupled receptors (aGPCRs), with 33 human homologs, is the second largest family of GPCRs. In addition to a seven-transmembrane α-helix-a structural feature of all GPCRs-the class of aGPCRs is characterized by the presence of a large N-terminal extracellular region....... In addition, all aGPCRs but one (GPR123) contain a GPCR autoproteolysis-inducing (GAIN) domain that mediates autoproteolytic cleavage at the GPCR autoproteolysis site motif to generate N- and a C-terminal fragments (NTF and CTF, respectively) during protein maturation. Subsequently, the NTF and CTF...... recent advances in understanding the biological functions, signaling mechanisms, and disease associations of the aGPCRs....

  11. Couplings in D(2,1;α) superconformal mechanics from the SU(2) perspective

    Energy Technology Data Exchange (ETDEWEB)

    Galajinsky, Anton [Laboratory of Mathematical Physics, Tomsk Polytechnic University,Lenin Ave. 30, 634050 Tomsk (Russian Federation)

    2017-03-09

    Dynamical realizations of the most general N=4 superconformal group in one dimension D(2,1;α) are reconsidered from the perspective of the R-symmetry subgroup SU(2). It is shown that any realization of the R-symmetry subalgebra in some phase space can be extended to a representation of the Lie superalgebra corresponding to D(2,1;α). Novel couplings of arbitrary number of supermultiplets of the type (1,4,3) and (0,4,4) to a single supermultiplet of either the type (3,4,1), or (4,4,0) are constructed. D(2,1;α) superconformal mechanics describing superparticles propagating near the horizon of the extreme Reissner-Nordström-AdS-dS black hole in four and five dimensions is considered. The parameter α is linked to the cosmological constant.

  12. [Plasma temperature calculation and coupling mechanism analysis of laser-double wire hybrid welding].

    Science.gov (United States)

    Zheng, Kai; Li, Huan; Yang, Li-Jun; Gu, Xiao-Yan; Gao, Ying

    2013-04-01

    The plasma radiation of laser-double wire hybrid welding was collected by using fiber spectrometer, the coupling mechanism of arc with laser was studied through high-speed photography during welding process, and the temperature of hybrid plasma was calculated by using the method of Boltzmann plot. The results indicated that with laser hybrid, luminance was enhanced; radiation intensity became stronger; arc was attracted to the laser point; cross section contracted and arc was more stable. The laser power, welding current and arc-arc distance are important factors that have great influence on electron temperature. Increase in the laser power, amplification of welding current and reduction of arc-arc distance can all result in the rise of temperature.

  13. A coupled thermo-mechanical pseudo inverse approach for preform design in forging

    Science.gov (United States)

    Thomas, Anoop Ebey; Abbes, Boussad; Li, Yu Ming; Abbes, Fazilay; Guo, Ying-Qiao; Duval, Jean-Louis

    2017-10-01

    Hot forging is a process used to form difficult to form materials as well as to achieve complex geometries. This is possible due to the reduction of yield stress at high temperatures and a subsequent increase in formability. Numerical methods have been used to predict the material yield and the stress/strain states of the final product. Pseudo Inverse Approach (PIA) developed in the context of cold forming provides a quick estimate of the stress and strain fields in the final product for a given initial shape. In this paper, PIA is extended to include the thermal effects on the forging process. A Johnson-Cook thermo-viscoplastic material law is considered and a staggered scheme is employed for the coupling between the mechanical and thermal problems. The results are compared with available commercial codes to show the efficiency and the limitations of PIA.

  14. Mechanical coupling of wind turbines to low lift rotodynamic water pumps

    Energy Technology Data Exchange (ETDEWEB)

    Burton, J.D.

    1988-01-01

    The mechanical coupling of wind turbines to rotodynamic water pumps (centrifugal and axial flow) via a step-up speed ratio G is examined. A procedure is outlined for the correct choice of G and for the sizing of the pump for a given wind turbine and wind regime. Specific speed of the pump is shown to be important not just in terms of selection to meet a given site head, but also because it is the major factor in determining the shape of the machine's characteristics and therefore the strategy to be adopted during the matching procedure. Sensitivity of the wind turbine-pump combination to site head fluctuation is examined via simple scaling relationships.

  15. A Coupled Model of Multiphase Flow, Reactive Biogeochemical Transport, Thermal Transport and Geo-Mechanics.

    Science.gov (United States)

    Tsai, C. H.; Yeh, G. T.

    2015-12-01

    In this investigation, a coupled model of multiphase flow, reactive biogeochemical transport, thermal transport and geo-mechanics in subsurface media is presented. It iteratively solves the mass conservation equation for fluid flow, thermal transport equation for temperature, reactive biogeochemical transport equations for concentration distributions, and solid momentum equation for displacement with successive linearization algorithm. With species-based equations of state, density of a phase in the system is obtained by summing up concentrations of all species. This circumvents the problem of having to use empirical functions. Moreover, reaction rates of all species are incorporated in mass conservation equation for fluid flow. Formation enthalpy of all species is included in the law of energy conservation as a source-sink term. Finite element methods are used to discretize the governing equations. Numerical experiments are presented to examine the accuracy and robustness of the proposed model. The results demonstrate the feasibility and capability of present model in subsurface media.

  16. Interplay between the folding mechanism and binding modes in folding coupled to binding processes.

    Science.gov (United States)

    Sharma, Rajendra; De Sancho, David; Muñoz, Victor

    2017-11-01

    Proteins that fold upon binding to their partners exhibit complex binding behavior such as induced-fit. But the connections between the folding mechanism and the binding mode remain unknown. Here we focus on the high affinity complex between the physiologically and marginally unstable, fast folder PSBD and the E1 subunit of pyruvate dehydrogenase. Using coarse-grained simulations we investigate the binding to E1 of a partially disordered PSBD under two folding scenarios: two-state and downhill. Our simulations show that induced-fit binding requires that PSBD folds-unfolds in the downhill folding regime. In contrast, a two-state folding PSBD must fold completely before it binds. The reason is that effective coupling between folding and binding involves partially folded conformations, which are only sufficiently populated under the downhill folding regime. Our results establish a direct mechanistic link between complex binding and downhill folding, supporting the idea that PSBD operates functionally as a conformational rheostat.

  17. Mechanism of coupling drug transport reactions located in two different membranes

    Directory of Open Access Journals (Sweden)

    Helen I. Zgurskaya

    2015-02-01

    Full Text Available Gram- negative bacteria utilize a diverse array of multidrug transporters to pump toxic compounds out of cells. Some transporters together with periplasmic membrane fusion proteins (MFPs and outer membrane channels assemble trans-envelope complexes that expel multiple antibiotics across outer membranes of Gram-negative bacteria and into the external medium. Others further potentiate this efflux by pumping drugs across the inner membrane into the periplasm. Together these transporters create a powerful network of efflux that protect bacteria against a broad range of antimicrobial agents. This review is focused on the mechanism of coupling transport reactions located in two different membranes of Gram-negative bacteria. Using a combination of biochemical, genetic and biophysical approaches we have reconstructed the sequence of events leading to the assembly of trans-envelope drug efflux complexes and characterized the roles of periplasmic and outer membrane proteins in this process. Our recent data suggest a critical step in the activation of intermembrane efflux pumps, which is controlled by MFPs. We propose that the reaction cycles of transporters are tightly coupled to the assembly of the trans-envelope complexes. Transporters and MFPs exist in the inner membrane as dormant complexes. The activation of complexes is triggered by MFP binding to the outer membrane channel, which leads to a conformational change in the membrane proximal domain of MFP needed for stimulation of transporters. The activated MFP-transporter complex engages the outer membrane channel to expel substrates across the outer membrane. The recruitment of the channel is likely triggered by binding of effectors (substrates to MFP or MFP-transporter complexes. This model together with recent structural and functional advances in the field of drug efflux provides a fairly detailed understanding of the mechanism of drug efflux across the two membranes.

  18. Implicit coupling of turbulent diffusion with chemical reaction mechanisms for prognostic atmospheric dispersion models

    Energy Technology Data Exchange (ETDEWEB)

    Berlowitz, D.R.

    1996-11-01

    In the last few decades the negative impact by humans on the thin atmospheric layer enveloping the earth, the basis for life on this planet, has increased steadily. In order to halt, or at least slow down this development, the knowledge and study of these anthropogenic influence has to be increased and possible remedies have to be suggested. An important tool for these studies are computer models. With their help the atmospheric system can be approximated and the various processes, which have led to the current situation can be quantified. They also serve as an instrument to assess short or medium term strategies to reduce this human impact. However, to assure efficiency as well as accuracy, a careful analysis of the numerous processes involved in the dispersion of pollutants in the atmosphere is called for. This should help to concentrate on the essentials and also prevent excessive usage of sometimes scarce computing resources. The basis of the presented work is the EUMAC Zooming Model (ETM), and particularly the component calculating the dispersion of pollutants in the atmosphere, the model MARS. The model has two main parts: an explicit solver, where the advection and the horizontal diffusion of pollutants are calculated, and an implicit solution mechanism, allowing the joint computation of the change of concentration due to chemical reactions, coupled with the respective influence of the vertical diffusion of the species. The aim of this thesis is to determine particularly the influence of the horizontal components of the turbulent diffusion on the existing implicit solver of the model. Suggestions for a more comprehensive inclusion of the full three dimensional diffusion operator in the implicit solver are made. This is achieved by an appropriate operator splitting. A selection of numerical approaches to tighten the coupling of the diffusion processes with the calculation of the applied chemical reaction mechanisms are examined. (author) figs., tabs., refs.

  19. [Arc spectrum diagnostic and heat coupling mechanism analysis of double wire pulsed MIG welding].

    Science.gov (United States)

    Liu, Yong-qiang; Li, Huan; Yang, Li-jun; Zheng, Kai; Gao, Ying

    2015-01-01

    A double wire pulsed MIG welding test system was built in the present paper, in order to analyze the heat-coupling mechanism of double wire pulsed MIG welding, and study are temperature field. Spectroscopic technique was used in diagnostic analysis of the are, plasma radiation was collected by using hollow probe method to obtain the arc plasma optical signal The electron temperature of double wire pulsed MIG welding arc plasma was calculated by using Boltzmann diagram method, the electron temperature distribution was obtained, a comprehensive analysis of the arc was conducted combined with the high speed camera technology and acquisition means of electricity signal. The innovation of this paper is the combination of high-speed camera image information of are and optical signal of arc plasma to analyze the coupling mechanism for dual arc, and a more intuitive analysis for are temperature field was conducted. The test results showed that a push-pull output was achieved and droplet transfer mode was a drop in a pulse in the welding process; Two arcs attracted each other under the action of a magnetic field, and shifted to the center of the arc in welding process, so a new heat center was formed at the geometric center of the double arc, and flowing up phenomenon occurred on the arc; Dual arc electronic temperature showed an inverted V-shaped distribution overall, and at the geometric center of the double arc, the arc electron temperature at 3 mm off the workpiece surface was the highest, which was 16,887.66 K, about 4,900 K higher than the lowest temperature 11,963.63 K.

  20. Theoretical study on the mechanism of Ni-catalyzed alkyl-alkyl Suzuki cross-coupling.

    Science.gov (United States)

    Li, Zhe; Jiang, Yuan-Ye; Fu, Yao

    2012-04-02

    Ni-catalyzed cross-coupling of unactivated secondary alkyl halides with alkylboranes provides an efficient way to construct alkyl-alkyl bonds. The mechanism of this reaction with the Ni/L1 (L1=trans-N,N'-dimethyl-1,2-cyclohexanediamine) system was examined for the first time by using theoretical calculations. The feasible mechanism was found to involve a Ni(I)-Ni(III) catalytic cycle with three main steps: transmetalation of [Ni(I)(L1)X] (X=Cl, Br) with 9-borabicyclo[3.3.1]nonane (9-BBN)R(1) to produce [Ni(I)(L1)(R(1))], oxidative addition of R(2) X with [Ni(I)(L1)(R(1))] to produce [Ni(III)(L1)(R(1))(R(2))X] through a radical pathway, and C-C reductive elimination to generate the product and [Ni(I)(L1)X]. The transmetalation step is rate-determining for both primary and secondary alkyl bromides. KOiBu decreases the activation barrier of the transmetalation step by forming a potassium alkyl boronate salt with alkyl borane. Tertiary alkyl halides are not reactive because the activation barrier of reductive elimination is too high (+34.7 kcal mol(-1)). On the other hand, the cross-coupling of alkyl chlorides can be catalyzed by Ni/L2 (L2=trans-N,N'-dimethyl-1,2-diphenylethane-1,2-diamine) because the activation barrier of transmetalation with L2 is lower than that with L1. Importantly, the Ni(0)-Ni(II) catalytic cycle is not favored in the present systems because reductive elimination from both singlet and triplet [Ni(II)(L1)(R(1))(R(2))] is very difficult. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. A high performance data parallel tensor contraction framework: Application to coupled electro-mechanics

    Science.gov (United States)

    Poya, Roman; Gil, Antonio J.; Ortigosa, Rogelio

    2017-07-01

    The paper presents aspects of implementation of a new high performance tensor contraction framework for the numerical analysis of coupled and multi-physics problems on streaming architectures. In addition to explicit SIMD instructions and smart expression templates, the framework introduces domain specific constructs for the tensor cross product and its associated algebra recently rediscovered by Bonet et al. (2015, 2016) in the context of solid mechanics. The two key ingredients of the presented expression template engine are as follows. First, the capability to mathematically transform complex chains of operations to simpler equivalent expressions, while potentially avoiding routes with higher levels of computational complexity and, second, to perform a compile time depth-first or breadth-first search to find the optimal contraction indices of a large tensor network in order to minimise the number of floating point operations. For optimisations of tensor contraction such as loop transformation, loop fusion and data locality optimisations, the framework relies heavily on compile time technologies rather than source-to-source translation or JIT techniques. Every aspect of the framework is examined through relevant performance benchmarks, including the impact of data parallelism on the performance of isomorphic and nonisomorphic tensor products, the FLOP and memory I/O optimality in the evaluation of tensor networks, the compilation cost and memory footprint of the framework and the performance of tensor cross product kernels. The framework is then applied to finite element analysis of coupled electro-mechanical problems to assess the speed-ups achieved in kernel-based numerical integration of complex electroelastic energy functionals. In this context, domain-aware expression templates combined with SIMD instructions are shown to provide a significant speed-up over the classical low-level style programming techniques.

  2. Effects of Drake Passage on the Ocean's Thermal and Mechanical Energy Budget in a Coupled AOGCM

    Science.gov (United States)

    von der Heydt, A. S.; Viebahn, J. P.

    2016-12-01

    During the Cenozoic Earth's climate has undergone a major long-term transition from `greenhouse' to `icehouse' conditions with extensive ice sheets in the polar regions of both hemispheres. The gradual cooling may be seen as response to the overall slowly decreasing atmospheric CO2-concentration due to weathering processes in the Earth System, however, continental geometry has changed considerably over this period and the long-term gradual trend was interrupted, by several rapid transitions and periods where temperature and greenhouse gas concentrations seem to be decoupled. The Eocene-Oligocene boundary ( 34 Ma, E/O) and mid-Miocene climatic transition ( 13 Ma, MCT) reflect major phases of Antarctic ice sheet build-up and global climate cooling, while Northern Hemisphere ice sheets developed much later ( 2.7Ma). Thresholds in atmospheric CO2-concentration together with feedback mechanisms related to land ice formation are among the favoured mechanisms of these climatic transitions, while the long-proposed ocean circulation changes caused by opening of tectonic gateways seem to play a less direct role. The opening of the Southern Ocean gateways, however, has eventually led to the development of today's strongest ocean current, the Antarctic Circumpolar Current, playing a major role in the transport properties of the global ocean circulation. The overall state of the global ocean circulation, therefore, must precondition the climate system to dramatic events such as major ice sheet formation. Closing Drake Passage in ocean-only and coupled climate models under otherwise present-day boundary conditions has become a classic experiment, indicating that there exists a considerable uncertainty in the climate response of those models to a closed Drake Passage. Here we quantify the climate response to a closed Drake Passage in a state-of-the-art coupled climate model (CESM). We show that the ocean gateway mechanism is robust in the sense that the equatorward expansion of

  3. Deep geothermal systems interpreted by coupled thermo-hydraulic-mechanical-chemical numerical modeling

    Science.gov (United States)

    Peters, Max; Lesueur, Martin; Held, Sebastian; Poulet, Thomas; Veveakis, Manolis; Regenauer-Lieb, Klaus; Kohl, Thomas

    2017-04-01

    The dynamic response of the geothermal reservoirs of Soultz-sous-Forêts (NE France) and a new site in Iceland are theoretically studied upon fluid injection and production. Since the Soultz case can be considered the most comprehensive project in the area of enhanced geothermal systems (EGS), it is tailored for the testing of forward modeling techniques that aim at the characterization of fluid dynamics and mechanical properties in any deeply-seated fractured cystalline reservoir [e.g. Held et al., 2014]. We present multi-physics finite element models using the recently developed framework MOOSE (mooseframework.org) that implicitly consider fully-coupled feedback mechanisms of fluid-rock interaction at depth where EGS are located (depth > 5 km), i.e. the effects of dissipative strain softening on chemical reactions and reactive transport [Poulet et al., 2016]. In a first suite of numerical experiments, we show that an accurate simulation of propagation fronts allows studying coupled fluid and heat transport, following preferred pathways, and the transport time of the geothermal fluid between injection and production wells, which is in good agreement with tracer experiments performed inside the natural reservoir. Based on induced seismicity experiments and related damage along boreholes, we concern with borehole instabilities resulting from pore pressure variations and (a)seismic creep in a second series of simulations. To this end, we account for volumetric and deviatoric components, following the approach of Veveakis et al. (2016), and discuss the mechanisms triggering slow earthquakes in the stimulated reservoirs. Our study will allow applying concepts of unconventional geomechanics, which were previously reviewed on a theoretical basis [Regenauer-Lieb et al., 2015], to substantial engineering problems of deep geothermal reservoirs in the future. REFERENCES Held, S., Genter, A., Kohl, T., Kölbel, T., Sausse, J. and Schoenball, M. (2014). Economic evaluation of

  4. Coupled and reduced dimensional modeling of respiratory mechanics during spontaneous breathing.

    Science.gov (United States)

    Ismail, M; Comerford, A; Wall, W A

    2013-11-01

    In this paper, we develop a total lung model based on a tree of 0D airway and acinar models for studying respiratory mechanics during spontaneous breathing. This model utilizes both computer tomography-based geometries and artificially generated lobe-filling airway trees to model the entire conducting region of the lung. Beyond the conducting airways, we develop an acinar model, which takes into account the alveolar tissue resistance, compliance, and the intrapleural pressure. With this methodology, we compare four different 0D models of airway mechanics and determine the best model based on a comparison with a 3D-0D coupled model of the conducting airways; this methodology is possible because the majority of airway resistance is confined to the lower generations, that is, the trachea and the first few bronchial generations. As an example application of the model, we simulate the flow and pressure dynamics under spontaneous breathing conditions, that is, at flow conditions driven purely by pleural space pressure. The results show good agreement, both qualitatively and quantitatively, with reported physiological values. One of the key advantages of this model is the ability to provide insight into lung ventilation in the peripheral regions. This is often crucial because this is where information, specifically for studying diseases and gas exchange, is needed. Thus, the model can be used as a tool for better understanding local peripheral lung mechanics without excluding the upper portions of the lung. This tool will be also useful for in vitro investigations of lung mechanics in both health and disease. Copyright © 2013 John Wiley & Sons, Ltd.

  5. Comprehensive stability analysis of disc brake vibrations including gyroscopic, negative friction slope and mode-coupling mechanisms

    Science.gov (United States)

    Kang, Jaeyoung; Krousgrill, Charles M.; Sadeghi, Farshid

    2009-07-01

    The current study investigates the disc brake squeal by using an annular disc in contact with two pads subject to distributed friction stresses. The disc and pads are modeled as rotating annular and stationary annular sector plates, respectively. Friction stress is described on the deformed disc surface as distributed non-conservative friction-couples and frictional follower forces. From disc doublet-mode and multiple-mode models, the mode-coupling mechanism influenced by disc rotation is examined. In automotive applications, the frictional mode-coupling resulting from friction couple is shown to be the major mechanism for dynamic destabilization, whereas the effects of disc rotation on flutter destabilization are found to be small. On the verge of stop, however, the rotation effects effectively stabilize the steady sliding. This comprehensive brake model has shown that there is a speed corresponding to maximum squeal propensity for each flutter mode.

  6. Numerical model of thermo-mechanical coupling for the tensile failure process of brittle materials

    Science.gov (United States)

    Fu, Yu; Wang, Zhe; Ren, Fengyu; Wang, Daguo

    2017-10-01

    A numerical model of thermal cracking with a thermo-mechanical coupling effect was established. The theory of tensile failure and heat conduction is used to study the tensile failure process of brittle materials, such as rock and concrete under high temperature environment. The validity of the model is verified by thick-wall cylinders with analytical solutions. The failure modes of brittle materials under thermal stresses caused by temperature gradient and different thermal expansion coefficient were studied by using a thick-wall cylinder model and an embedded particle model, respectively. In the thick-wall cylinder model, different forms of cracks induced by temperature gradient were obtained under different temperature boundary conditions. In the embedded particle model, radial cracks were produced in the medium part with lower tensile strength when temperature increased because of the different thermal expansion coefficient. Model results are in good agreement with the experimental results, thereby providing a new finite element method for analyzing the thermal damage process and mechanism of brittle materials.

  7. Numerical model of thermo-mechanical coupling for the tensile failure process of brittle materials

    Directory of Open Access Journals (Sweden)

    Yu Fu

    2017-10-01

    Full Text Available A numerical model of thermal cracking with a thermo-mechanical coupling effect was established. The theory of tensile failure and heat conduction is used to study the tensile failure process of brittle materials, such as rock and concrete under high temperature environment. The validity of the model is verified by thick-wall cylinders with analytical solutions. The failure modes of brittle materials under thermal stresses caused by temperature gradient and different thermal expansion coefficient were studied by using a thick-wall cylinder model and an embedded particle model, respectively. In the thick-wall cylinder model, different forms of cracks induced by temperature gradient were obtained under different temperature boundary conditions. In the embedded particle model, radial cracks were produced in the medium part with lower tensile strength when temperature increased because of the different thermal expansion coefficient. Model results are in good agreement with the experimental results, thereby providing a new finite element method for analyzing the thermal damage process and mechanism of brittle materials.

  8. An Integrative Model of the Cardiovascular System Coupling Heart Cellular Mechanics with Arterial Network Hemodynamics

    Science.gov (United States)

    Kim, Young-Tae; Lee, Jeong Sang; Youn, Chan-Hyun; Choi, Jae-Sung

    2013-01-01

    The current study proposes a model of the cardiovascular system that couples heart cell mechanics with arterial hemodynamics to examine the physiological role of arterial blood pressure (BP) in left ventricular hypertrophy (LVH). We developed a comprehensive multiphysics and multiscale cardiovascular model of the cardiovascular system that simulates physiological events, from membrane excitation and the contraction of a cardiac cell to heart mechanics and arterial blood hemodynamics. Using this model, we delineated the relationship between arterial BP or pulse wave velocity and LVH. Computed results were compared with existing clinical and experimental observations. To investigate the relationship between arterial hemodynamics and LVH, we performed a parametric study based on arterial wall stiffness, which was obtained in the model. Peak cellular stress of the left ventricle and systolic blood pressure (SBP) in the brachial and central arteries also increased; however, further increases were limited for higher arterial stiffness values. Interestingly, when we doubled the value of arterial stiffness from the baseline value, the percentage increase of SBP in the central artery was about 6.7% whereas that of the brachial artery was about 3.4%. It is suggested that SBP in the central artery is more critical for predicting LVH as compared with other blood pressure measurements. PMID:23960442

  9. Pore-scale modeling of hydromechanical coupled mechanics in hydrofracturing process

    Science.gov (United States)

    Chen, Zhiqiang; Wang, Moran

    2017-05-01

    Hydrofracturing is an important technique in petroleum industry to stimulate well production. Yet the mechanism of induced fracture growth is still not fully understood, which results in some unsatisfactory wells even with hydrofracturing treatments. In this work we establish a more accurate numerical framework for hydromechanical coupling, where the solid deformation and fracturing are modeled by discrete element method and the fluid flow is simulated directly by lattice Boltzmann method at pore scale. After validations, hydrofracturing is simulated with consideration on the strength heterogeneity effects on fracture geometry and microfailure mechanism. A modified topological index is proposed to quantify the complexity of fracture geometry. The results show that strength heterogeneity has a significant influence on hydrofracturing. In heterogeneous samples, the fracturing behavior is crack nucleation around the tip of fracture and connection of it to the main fracture, which is usually accompanied by shear failure. However, in homogeneous ones the fracture growth is achieved by the continuous expansion of the crack, where the tensile failure often dominates. It is the fracturing behavior that makes the fracture geometry in heterogeneous samples much more complex than that in homogeneous ones. In addition, higher pore pressure leads to more shear failure events for both heterogeneous and homogeneous samples.

  10. An integrative model of the cardiovascular system coupling heart cellular mechanics with arterial network hemodynamics.

    Science.gov (United States)

    Kim, Young-Tae; Lee, Jeong Sang; Youn, Chan-Hyun; Choi, Jae-Sung; Shim, Eun Bo

    2013-08-01

    The current study proposes a model of the cardiovascular system that couples heart cell mechanics with arterial hemodynamics to examine the physiological role of arterial blood pressure (BP) in left ventricular hypertrophy (LVH). We developed a comprehensive multiphysics and multiscale cardiovascular model of the cardiovascular system that simulates physiological events, from membrane excitation and the contraction of a cardiac cell to heart mechanics and arterial blood hemodynamics. Using this model, we delineated the relationship between arterial BP or pulse wave velocity and LVH. Computed results were compared with existing clinical and experimental observations. To investigate the relationship between arterial hemodynamics and LVH, we performed a parametric study based on arterial wall stiffness, which was obtained in the model. Peak cellular stress of the left ventricle and systolic blood pressure (SBP) in the brachial and central arteries also increased; however, further increases were limited for higher arterial stiffness values. Interestingly, when we doubled the value of arterial stiffness from the baseline value, the percentage increase of SBP in the central artery was about 6.7% whereas that of the brachial artery was about 3.4%. It is suggested that SBP in the central artery is more critical for predicting LVH as compared with other blood pressure measurements.

  11. Numerical modelling of levee stability based on coupled mechanical, thermal and hydrogeological processes

    Directory of Open Access Journals (Sweden)

    Dwornik Maciej

    2016-01-01

    Full Text Available The numerical modelling of coupled mechanical, thermal and hydrogeological processes for a soil levee is presented in the paper. The modelling was performed for a real levee that was built in Poland as a part of the ISMOP project. Only four parameters were changed to build different flood waves: the water level, period of water increase, period of water decrease, and period of low water level after the experiment. Results of numerical modelling shows that it is possible and advisable to calculate simultaneously changes of thermal and hydro-mechanical fields. The presented results show that it is also possible to use thermal sensors in place of more expensive pore pressure sensors, with some limitations. The results of stability analysis show that the levee is less stable when the water level decreases, after which factor of safety decreases significantly. For all flooding wave parameters described in the paper, the levee is very stable and factor of safety variations for any particular stage were not very large.

  12. Multi-beam laser Doppler vibrometry for acoustic landmine detection using airborne and mechanically coupled vibration

    Science.gov (United States)

    Aranchuk, Vyacheslav; Sabatier, James M.; Lal, Amit K.; Hess, Cecil F.; Burgett, Richard D.; O'Neill, Michael

    2005-06-01

    Acoustic-to-seismic coupling-based technology using a multi-beam laser Doppler vibrometer (LDV) as a vibration sensor has proved itself as a potential confirmatory sensor for buried landmine detection. The multi-beam LDV simultaneously measures the vibration of the ground at 16 points spread over a 1-meter line. The multi-beam LDV was used in two modes of operation: stop-and-stare, and continuously scanning beams. The noise floor of measurements in the continuously scanning mode increased with increasing scanning speed. This increase in the velocity noise floor is caused by dynamic speckles. The influence of amplitude and phase fluctuations of the Doppler signal due to dynamic speckles on the phase locked loop (PLL) demodulated output is discussed in the paper. Either airborne sound or mechanical shakers can be used as a source to excite vibration of the ground. A specially-designed loudspeaker array and mechanical shakers were used in the frequency range from 85-2000 Hz to excite vibrations in the ground and elicit resonances in the mine. The efficiency of these two methods of excitation has been investigated and is discussed in the paper. This research is supported by the U. S. Army Research, Development, and Engineering Command, Night, Vision and Electronic Sensors Directorate under Contract DAAB15-02-C-0024.

  13. Microbial community succession mechanism coupling with adaptive evolution of adsorption performance in chalcopyrite bioleaching.

    Science.gov (United States)

    Feng, Shoushuai; Yang, Hailin; Wang, Wu

    2015-09-01

    The community succession mechanism of Acidithiobacillus sp. coupling with adaptive evolution of adsorption performance were systematically investigated. Specifically, the μmax of attached and free cells was increased and peak time was moved ahead, indicating both cell growth of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans was promoted. In the mixed strains system, the domination courses of A. thiooxidans was dramatically shortened from 22th day to 15th day, although community structure finally approached to the normal system. Compared to A. ferrooxidans, more positive effects of adaptive evolution on cell growth of A. thiooxidans were shown in either single or mixed strains system. Moreover, higher concentrations of sulfate and ferric ions indicated that both sulfur and iron metabolism was enhanced, especially of A. thiooxidans. Consistently, copper ion production was improved from 65.5 to 88.5 mg/L. This new adaptive evolution and community succession mechanism may be useful for guiding similar bioleaching processes. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. CO adsorption, dissociation and coupling formation mechanisms on Fe2C(001) surface

    Science.gov (United States)

    Yu, Xiaohu; Zhang, Xuemei; Meng, Yan; Zhao, Yaoping; Li, Yuan; Xu, Wei; Liu, Zhong

    2018-03-01

    By means of density functional theory calculations and atomic thermodynamics, we systematically investigated the CO adsorption on the Fe2C(001) surface at different coverage. It has been found that CO prefers to adsorb on the surface iron atom at low coverage (1-8 CO); CO prefers to adsorb at the bridge site of Fe and C atoms at high coverage (9-12 CO). Eight CO molecules binding on the Fe2C(001) surface is favorable thermodynamically as indicated by the stepwise adsorption energy. The phase diagram shows that addition of more CO molecules up to a number of 8 is thermodynamically favorable, and that the incremental energy gained by adding one more CO molecule is almost constant up to 4 CO molecules, decreases up to 8 CO molecules, after which it becomes thermodynamically unfavorable to add more CO molecules. Probability distribution of different singe-CO adsorbed states on the Fe2C(001) surface as function of temperature shows that CO dissociation and coupling are least preferred, indicating that carbide mechanism is not dominant in the iron-based Fischer-Tropsch synthesis reaction. The projected density of states (PDOS) was used to analyze the CO adsorption mechanism.

  15. Fluid-structure interaction including volumetric coupling with homogenised subdomains for modeling respiratory mechanics.

    Science.gov (United States)

    Yoshihara, Lena; Roth, Christian J; Wall, Wolfgang A

    2017-04-01

    In this article, a novel approach is presented for combining standard fluid-structure interaction with additional volumetric constraints to model fluid flow into and from homogenised solid domains. The proposed algorithm is particularly interesting for investigations in the field of respiratory mechanics as it enables the mutual coupling of airflow in the conducting part and local tissue deformation in the respiratory part of the lung by means of a volume constraint. In combination with a classical monolithic fluid-structure interaction approach, a comprehensive model of the human lung can be established that will be useful to gain new insights into respiratory mechanics in health and disease. To illustrate the validity and versatility of the novel approach, three numerical examples including a patient-specific lung model are presented. The proposed algorithm proves its capability of computing clinically relevant airflow distribution and tissue strain data at a level of detail that is not yet achievable, neither with current imaging techniques nor with existing computational models. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  16. A Monod-Wyman-Changeux mechanism can explain G protein-coupled receptor (GPCR) allosteric modulation.

    Science.gov (United States)

    Canals, Meritxell; Lane, J Robert; Wen, Adriel; Scammells, Peter J; Sexton, Patrick M; Christopoulos, Arthur

    2012-01-02

    The Monod-Wyman-Changeux (MWC) model was initially proposed to describe the allosteric properties of regulatory enzymes and subsequently extended to receptors. Yet despite GPCRs representing the largest family of receptors and drug targets, no study has systematically evaluated the MWC mechanism as it applies to GPCR allosteric ligands. We reveal how the recently described allosteric modulator, benzyl quinolone carboxylic acid (BQCA), behaves according to a strict, two-state MWC mechanism at the M1 muscarinic acetylcholine receptor (mAChR). Despite having a low affinity for the M1 mAChR, BQCA demonstrated state dependence, exhibiting high positive cooperativity with orthosteric agonists in a manner that correlated with efficacy but negative cooperativity with inverse agonists. The activity of BQCA was significantly increased at a constitutively active M1 mAChR but abolished at an inactive mutant. Interestingly, BQCA possessed intrinsic signaling efficacy, ranging from near-quiescence to full agonism depending on the coupling efficiency of the chosen intracellular pathway. This latter cellular property also determined the difference in magnitude of positive cooperativity between BQCA and the orthosteric agonist, carbachol, across pathways. The lack of additional, pathway-biased, allosteric modulation by BQCA was confirmed in genetically engineered yeast strains expressing different chimeras between the endogenous yeast G(pa1) protein and human Gα subunits. These findings define a chemical biological framework that can be applied to the study and classification of allosteric modulators across different GPCR families.

  17. Tuning intermetallic electronic coupling in polyruthenium systems ...

    Indian Academy of Sciences (India)

    molecular architecture. SANDEEP GHUMAAN and GOUTAM KUMAR LAHIRI*. Department of Chemistry, Indian Institute of Technology – Bombay, Powai, Mumbai 400 076 e-mail: lahiri@chem.iitb.ac.in. Abstract. A large number of polynuclear ruthenium complexes encompassing selective combinations of spacer (bridging ...

  18. Tuned-circuit Johnson noise thermometry

    Science.gov (United States)

    Roberts, M. J.; Blalock, T. V.; Shepard, R. L.

    Three tuned circuits that can be used in Johnson noise thermometry have been analyzed; series resistance-inductance-capacitance (RLC), parallel RLC, and transformer coupled. Tuned circuits allow the temperature of the sensor to be determined by a single noise voltage, which is ideally independent of the resistance of the sensor, thereby reducing the complexity of temperature-measuring systems for space applications. Direct-coupled and transformer-coupled tuned circuits may offer advantage to the SP-100 system designer interfacing with data systems. A study was performed to establish whether the advantages of the ideal tuned circuits would be obtained with real, lossy inductive components and would provide a measurement system independent of aging and temperature effects on sensor resistance. Theoretical mean-squared output voltage dependence on sensor temperature and resistance, output capacitor value, and inductor temperature and resistance are derived for the series and parallel RLC cases. It is shown for tuned circuits using lossless inductors that the mean squared voltage is kT sub R/C, where T sub R is the sensor temperature and C is the capacitance of the capacitor. For lossy inductors and transformers, the mean-squared capacitor voltage is a function of sensor resistance, which may change in an unknown manner during an extended mission.

  19. Diffusive coupling can discriminate between similar reaction mechanisms in an allosteric enzyme system

    Directory of Open Access Journals (Sweden)

    Nicola Ernesto M

    2010-11-01

    Full Text Available Abstract Background A central question for the understanding of biological reaction networks is how a particular dynamic behavior, such as bistability or oscillations, is realized at the molecular level. So far this question has been mainly addressed in well-mixed reaction systems which are conveniently described by ordinary differential equations. However, much less is known about how molecular details of a reaction mechanism can affect the dynamics in diffusively coupled systems because the resulting partial differential equations are much more difficult to analyze. Results Motivated by recent experiments we compare two closely related mechanisms for the product activation of allosteric enzymes with respect to their ability to induce different types of reaction-diffusion waves and stationary Turing patterns. The analysis is facilitated by mapping each model to an associated complex Ginzburg-Landau equation. We show that a sequential activation mechanism, as implemented in the model of Monod, Wyman and Changeux (MWC, can generate inward rotating spiral waves which were recently observed as glycolytic activity waves in yeast extracts. In contrast, in the limiting case of a simple Hill activation, the formation of inward propagating waves is suppressed by a Turing instability. The occurrence of this unusual wave dynamics is not related to the magnitude of the enzyme cooperativity (as it is true for the occurrence of oscillations, but to the sensitivity with respect to changes of the activator concentration. Also, the MWC mechanism generates wave patterns that are more stable against long wave length perturbations. Conclusions This analysis demonstrates that amplitude equations, which describe the spatio-temporal dynamics near an instability, represent a valuable tool to investigate the molecular effects of reaction mechanisms on pattern formation in spatially extended systems. Using this approach we have shown that the occurrence of inward

  20. Vinculin promotes cell spreading by mechanically coupling integrins to the cytoskeleton

    Science.gov (United States)

    Ezzell, R. M.; Goldmann, W. H.; Wang, N.; Parasharama, N.; Ingber, D. E.

    1997-01-01

    Mouse F9 embryonic carcinoma 5.51 cells that lack the cytoskeletal protein vinculin spread poorly on extracellular matrix compared with wild-type F9 cells or two vinculin-transfected clones (5.51Vin3 and Vin4; Samuels et al., 1993, J. Cell Biol. 121, 909-921). In the present study, we used this model system to determine how the presence of vinculin promotes cytoskeletal alterations and associated changes in cell shape. Microscopic analysis of cell spreading at early times, revealed that 5.51 cells retained the ability to form filopodia; however, they could not form lamellipodia, assemble stress fibers, or efficiently spread over the culture substrate. Detergent (Triton X-100) studies revealed that these major differences in cell morphology and cytoskeletal organization did not result from differences in levels of total polymerized or cross-linked actin. Biochemical studies showed that 5.51 cells, in addition to lacking vinculin, exhibited slightly reduced levels of alpha-actinin and paxillin in their detergent-insoluble cytoskeleton. The absence of vinculin correlated with a decrease in the mechanical stiffness of the integrin-cytoskeleton linkage, as measured using cell magnetometry. Furthermore, when vinculin was replaced by transfection in 5.51Vin3 and 5.51Vin4 cells, the levels of cytoskeletal-associated alpha-actinin and paxillin, the efficiency of transmembrane mechanical coupling, and the formation of actin stress fibers were all restored to near wild-type levels. These findings suggest that vinculin may promote cell spreading by stabilizing focal adhesions and transferring mechanical stresses that drive cytoskeletal remodeling, rather than by altering the total level of actin polymerization or cross-linking.

  1. Methods and Mechanisms for Cross-Electrophile Coupling of Csp2 Halides with Alkyl Electrophiles

    OpenAIRE

    Weix, Daniel J.

    2015-01-01

    Conspectus Cross-electrophile coupling, the cross-coupling of two different electrophiles, avoids the need for preformed carbon nucleophiles, but development of general methods has lagged behind cross-coupling and C?H functionalization. A central reason for this slow development is the challenge of selectively coupling two substrates that are alike in reactivity. This Account describes the discovery of generally cross-selective reactions of aryl halides and acyl halides with alkyl halides, th...

  2. The Tuning Song.

    Science.gov (United States)

    McClanahan, Dennis

    2000-01-01

    Provides the song "Can't Get in Tune Blues" to help orchestra string students determine whether their instruments are in tune. Explains that the song teaches students the pitch relationships among strings and gives them valuable open-string bowing practice. Includes the music and one variation. (CMK)

  3. Coupled thermo-hydro-mechanical modeling of heat extraction from the Tattapani geothermal field, India

    Science.gov (United States)

    Nand Pandey, Sachchida; Vishal, Vikram

    2017-04-01

    Modeling of coupled thermo-hydro-mechanical processes in enhanced geothermal systems is presented using the finite element method of modeling for a 3-D domain. The reservoir consists of a single horizontal fracture surrounded by low permeable rock matrix. The flow is imposed on a fracture plane, consisting of a doublet system. The reservoir rock mechanical properties were taken from the field data of the Tattapani geothermal field, India. We investigate the effects of injection temperature and mass flow rate on the energy output. The results indicate that temperature and pressure changes within the reservoirs occur due to injection of cold water. The temperature drop and fluid overpressure inside the reservoirs/fracture affect the transport properties of the fracture. The spatial-temporal variations of fracture aperture inside the reservoir greatly impact the thermal drawdown and therefore net energy output. The results showed that maximum aperture evolution occurs near the injection zone than the production zone. The fracture aperture evolution is a result of combined effects of thermal stress and fluid overpressure inside the fracture. The fracture opening reduces the injection pressure required to circulate the fixed volume of water. The effects of the injection temperature on heat extraction were also analyzed under different reservoir formations. The results indicate that reservoir permeability plays a significant role on heat extraction, highlighting the important effect of water losses. For each factor, it is concluded that thermal breakthrough primarily depends on injection temperate, mass flow rate, reservoir permeability and well distances. The results of this study can help in choosing the operational parameters for successful operation of geothermal system. The study will also be helpful to optimize the EGS performance under varying reservoir conditions.

  4. Experimental evaluation of analyte excitation mechanisms in the inductively coupled plasma

    Science.gov (United States)

    Lehn, Scott A.; Hieftje, Gary M.

    2003-10-01

    The inductively coupled plasma (ICP) is a justifiably popular source for atomic emission spectrometry. However, despite its popularity, the ICP is still only partially understood. Even the mechanisms of analyte excitation remain unclear; some energy levels are quite clearly populated by charge transfer while others might be populated by electron-ion recombination, by electron impact, or by Penning processes. Distinguishing among these alternatives is possible by means of a steady-state kinetics approach that examines correlations between the emission of a selected atom, ion, or level and the local number densities of species assumed to produce the excitation. In an earlier investigation, strong correlations were found between either calcium atom or ion emission and selected combinations of calcium atom or ion number densities and electron number densities in the plasma. However, all radially resolved data employed in the earlier study were produced from Abel inversion and from measurements that were crude by today's standards. Now, by means of tomographic imaging, laser-saturated atomic fluorescence, and Thomson and Rayleigh scattering, it is possible to measure the required radially resolved data without Abel inversion and with far greater fidelity. The correlations previously studied for calcium have been investigated with these more reliable data. Ion-electron recombination, either radiative or with argon as a third body, was determined to be the most likely excitation mechanism for calcium atom, while electron impact appeared to be the most important process to produce excite-state calcium ions. These results were consistent with the previous study. However, the present study suggests that collisional deactivation, rather than radiative decay, is the most likely mode of returning both calcium atoms and ions to the ground state.

  5. Coupling between chemical degradation and mechanical behaviour of leached concrete; Couplage degradation chimique - comportement en compression du beton

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, V.H

    2005-10-15

    This work is in the context of the long term behavior of concrete employed in radioactive waste disposal. The objective is to study the coupled chemo-mechanical modelling of concrete. In the first part of this contribution, experimental investigations are described where the effects of the calcium leaching process of concrete on its mechanical properties are highlighted. An accelerated method has been chosen to perform this leaching process by using an ammonium nitrate solution. In the second part, we present a coupled phenomenological chemo-mechanical model that represents the degradation of concrete materials. On one hand, the chemical behavior is described by the simplified calcium leaching approach of cement paste and mortar. Then a homogenization approach using the asymptotic development is presented to take into account the influence of the presence of aggregates in concrete. And on the other hand, the mechanical part of the modelling is given. Here continuum damage mechanics is used to describe the mechanical degradation of concrete. The growth of inelastic strains observed during the mechanical tests is describes by means of a plastic like model. The model is established on the basis of the thermodynamics of irreversible processes framework. The coupled nonlinear problem at hand is addressed within the context of the finite element method. Finally, numerical simulations are compared with the experimental results for validation. (author)

  6. Mechanisms of Lipid Scrambling by the G Protein-Coupled Receptor Opsin.

    Science.gov (United States)

    Morra, Giulia; Razavi, Asghar M; Pandey, Kalpana; Weinstein, Harel; Menon, Anant K; Khelashvili, George

    2017-12-18

    Several class-A G protein-coupled receptor (GPCR) proteins act as constitutive phospholipid scramblases catalyzing the transbilayer translocation of >10,000 phospholipids per second when reconstituted into synthetic vesicles. To address the molecular mechanism by which these proteins facilitate rapid lipid scrambling, we carried out large-scale ensemble atomistic molecular dynamics simulations of the opsin GPCR. We report that, in the process of scrambling, lipid head groups traverse a dynamically revealed hydrophilic pathway in the region between transmembrane helices 6 and 7 of the protein while their hydrophobic tails remain in the bilayer environment. We present quantitative kinetic models of the translocation process based on Markov State Model analysis. As key residues on the lipid translocation pathway are conserved within the class-A GPCR family, our results illuminate unique aspects of GPCR structure and dynamics while providing a rigorous basis for the design of variants of these proteins with defined scramblase activity. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Molecular Mechanism of Selectivity among G Protein-Coupled Receptor Kinase 2 Inhibitors

    Energy Technology Data Exchange (ETDEWEB)

    Thal, David M.; Yeow, Raymond Y.; Schoenau, Christian; Huber, Jochen; Tesmer, John J.G. (Sanofi); (Michigan)

    2012-07-11

    G protein-coupled receptors (GPCRs) are key regulators of cell physiology and control processes ranging from glucose homeostasis to contractility of the heart. A major mechanism for the desensitization of activated GPCRs is their phosphorylation by GPCR kinases (GRKs). Overexpression of GRK2 is strongly linked to heart failure, and GRK2 has long been considered a pharmaceutical target for the treatment of cardiovascular disease. Several lead compounds developed by Takeda Pharmaceuticals show high selectivity for GRK2 and therapeutic potential for the treatment of heart failure. To understand how these drugs achieve their selectivity, we determined crystal structures of the bovine GRK2-G{beta}{gamma} complex in the presence of two of these inhibitors. Comparison with the apoGRK2-G{beta}{gamma} structure demonstrates that the compounds bind in the kinase active site in a manner similar to that of the AGC kinase inhibitor balanol. Both balanol and the Takeda compounds induce a slight closure of the kinase domain, the degree of which correlates with the potencies of the inhibitors. Based on our crystal structures and homology modeling, we identified five amino acids surrounding the inhibitor binding site that we hypothesized could contribute to inhibitor selectivity. However, our results indicate that these residues are not major determinants of selectivity among GRK subfamilies. Rather, selectivity is achieved by the stabilization of a unique inactive conformation of the GRK2 kinase domain.

  8. Indian monsoon and the elevated-heat-pump mechanism in a coupled aerosol-climate model

    Science.gov (United States)

    D'Errico, Miriam; Cagnazzo, Chiara; Fogli, Pier Giuseppe; Lau, William K. M.; von Hardenberg, Jost; Fierli, Federico; Cherchi, Annalisa

    2015-09-01

    A coupled aerosol-atmosphere-ocean-sea ice climate model is used to explore the interaction between aerosols and the Indian summer monsoon precipitation on seasonal-to-interannual time scales. Results show that when increased aerosol loading is found on the Himalayas slopes in the premonsoon period (April-May), intensification of early monsoon rainfall over India and increased low-level westerly flow follow, in agreement with the elevated-heat-pump mechanism. The increase in rainfall during the early monsoon season has a cooling effect on the land surface. In the same period, enhanced surface cooling may also be amplified through solar dimming by more cloudiness and aerosol loading, via increased dust transported by low-level westerly flow. The surface cooling causes subsequent reduction in monsoon rainfall in July-August over India. The time-lagged nature of the reasonably realistic response of the model to aerosol forcing suggests that absorbing aerosols, besides their potential key roles in impacting monsoon water cycle and climate, may influence the seasonal variability of the Indian summer monsoon.

  9. A Coupled Thermo-Hydro-Mechanical Model of Jointed Hard Rock for Compressed Air Energy Storage

    Directory of Open Access Journals (Sweden)

    Xiaoying Zhuang

    2014-01-01

    Full Text Available Renewable energy resources such as wind and solar are intermittent, which causes instability when being connected to utility grid of electricity. Compressed air energy storage (CAES provides an economic and technical viable solution to this problem by utilizing subsurface rock cavern to store the electricity generated by renewable energy in the form of compressed air. Though CAES has been used for over three decades, it is only restricted to salt rock or aquifers for air tightness reason. In this paper, the technical feasibility of utilizing hard rock for CAES is investigated by using a coupled thermo-hydro-mechanical (THM modelling of nonisothermal gas flow. Governing equations are derived from the rules of energy balance, mass balance, and static equilibrium. Cyclic volumetric mass source and heat source models are applied to simulate the gas injection and production. Evaluation is carried out for intact rock and rock with discrete crack, respectively. In both cases, the heat and pressure losses using air mass control and supplementary air injection are compared.

  10. Partitioned fluid-solid coupling for cardiovascular blood flow: left-ventricular fluid mechanics.

    Science.gov (United States)

    Krittian, Sebastian; Janoske, Uwe; Oertel, Herbert; Böhlke, Thomas

    2010-04-01

    We present a 3D code-coupling approach which has been specialized towards cardiovascular blood flow. For the first time, the prescribed geometry movement of the cardiovascular flow model KaHMo (Karlsruhe Heart Model) has been replaced by a myocardial composite model. Deformation is driven by fluid forces and myocardial response, i.e., both its contractile and constitutive behavior. Whereas the arbitrary Lagrangian-Eulerian formulation (ALE) of the Navier-Stokes equations is discretized by finite volumes (FVM), the solid mechanical finite elasticity equations are discretized by a finite element (FEM) approach. Taking advantage of specialized numerical solution strategies for non-matching fluid and solid domain meshes, an iterative data-exchange guarantees the interface equilibrium of the underlying governing equations. The focus of this work is on left-ventricular fluid-structure interaction based on patient-specific magnetic resonance imaging datasets. Multi-physical phenomena are described by temporal visualization and characteristic FSI numbers. The results gained show flow patterns that are in good agreement with previous observations. A deeper understanding of cavity deformation, blood flow, and their vital interaction can help to improve surgical treatment and clinical therapy planning.

  11. Relativistic coupling of internal and centre of mass dynamics in classical and simple bound quantum mechanical systems

    Science.gov (United States)

    E Krause, Dennis; Lee, Inbum

    2017-07-01

    Although special relativity and quantum mechanics revolutionised physics in the early 20th century, the consequences of combining these two theories are still being explored a hundred years later, usually using the formidable theoretical machinery of quantum field theory. However, a formalism accessible to undergraduates has been recently developed which shows how the centre of mass and internal dynamics of classical and quantum systems is relativistically coupled with interesting consequences. Here we explore some of the implications of this coupling, first classically, where we find that the dynamics of the system is time dilated when moving relative to another inertial frame. We then apply the dynamics to a quantum 2-level atom bound in a one-dimensional infinite potential well, and show that the coupling produces collapses and revivals in quantum interference. This example provides an illustration of how the combination of special relativity and quantum mechanics can be studied in situations familiar to most undergraduates.

  12. A cortically-inspired model for inverse kinematics computation of a humanoid finger with mechanically coupled joints.

    Science.gov (United States)

    Gentili, Rodolphe J; Oh, Hyuk; Kregling, Alissa V; Reggia, James A

    2016-05-19

    The human hand's versatility allows for robust and flexible grasping. To obtain such efficiency, many robotic hands include human biomechanical features such as fingers having their two last joints mechanically coupled. Although such coupling enables human-like grasping, controlling the inverse kinematics of such mechanical systems is challenging. Here we propose a cortical model for fine motor control of a humanoid finger, having its two last joints coupled, that learns the inverse kinematics of the effector. This neural model functionally mimics the population vector coding as well as sensorimotor prediction processes of the brain's motor/premotor and parietal regions, respectively. After learning, this neural architecture could both overtly (actual execution) and covertly (mental execution or motor imagery) perform accurate, robust and flexible finger movements while reproducing the main human finger kinematic states. This work contributes to developing neuro-mimetic controllers for dexterous humanoid robotic/prosthetic upper-extremities, and has the potential to promote human-robot interactions.

  13. Java performance tuning

    CERN Document Server

    Shirazi, Jack

    2003-01-01

    Performance has been an important issue for Java developers ever since the first version hit the streets. Over the years, Java performance has improved dramatically, but tuning is essential to get the best results, especially for J2EE applications. You can never have code that runs too fast. Java Peformance Tuning, 2nd edition provides a comprehensive and indispensable guide to eliminating all types of performance problems. Using many real-life examples to work through the tuning process in detail, JPT shows how tricks such as minimizing object creation and replacing strings with arrays can

  14. iTunes music

    CERN Document Server

    Katz, Bob

    2013-01-01

    Apple's exciting new Mastered for iTunes (MFiT) initiative, introduced in early 2012, introduces new possibilities for delivering high-quality audio. For the first time, record labels and program producers are encouraged to deliver audio materials to iTunes in a high resolution format, which can produce better-sounding masters. In iTunes Music, author and world-class mastering engineer Bob Katz starts out with the basics, surveys the recent past, and brings you quickly up to the present-where the current state of digital audio is bleak. Katz explains the evolution of

  15. New Science ang technology development about CSES and LAIC coupling mechanism

    Science.gov (United States)

    Zhang, X.; Zhao, S.; Zhou, C.; Ren, Z.; Wu, Y.

    2016-12-01

    China CSES satellite will be launched in 2017. There are eight scientific payloads onboard. In order to bring them into full play, some new technologies and science have been developed in data processing and LAIC coupling mechanism. Based on the GPS constellation, the assimilation model of ionosphere on Ne has been developed by using EOF method., where E and F layer have been calculated separately under different coordinate systems. Furthermore, the Hall and Pederson conductivity have been obtained at the altitude of 90-500km. By using the TBB receiver data, the ionospheric tomography technology has been developed by employing the methods of Truncated Singular Value Decomposition, Spherical Function and Empirical Orthogonal Function (EOF). On the basis of beacon receiver data in China, the Ne profiles along the observing links have been built up, and their temporal features have been studied. The full wave propagation model of VLF radio waves has been improved, and the two-dimensional calculating results are displayed to reveal the spatial distribution features of these radio waves. The actual observation on DEMETER satellite of ground transmitters is compared with the 2D theoretical results, and their consistence verifies the reliability of the model. By emitting the high power HF signals into the space, one can disturb and cause the heating phenomena in lower and topside ionosphere. Three heating events have been chosen out in SURA-DEMETER experiments. Based on the Ohmic heating theory, a 3D model has been constructed to simulate the heating process, in which the disturbed amplitudes in Ne are close to the actual observing under different ionospheric state. In the LAIC model related to earthquake research, the DC electric field coupling model has been paid more attention in recent years.Some simultaneous variation phenomena have been obtained around earthquakes. To explain these disturbances, the electric field model is suggested and improved, in which the

  16. An application of nonlinear supratransmission to the propagation of binary signals in weakly damped, mechanical systems of coupled oscillators

    Energy Technology Data Exchange (ETDEWEB)

    Macias-Diaz, J.E. [Departamento de Matematicas y Fisica, Universidad Autonoma de Aguascalientes, Aguascalientes, Ags. 20100 (Mexico) and Department of Physics, University of New Orleans, New Orleans, LA 70148 (United States)]. E-mail: jemacias@correo.uaa.mx; Puri, A. [Department of Physics, University of New Orleans, New Orleans, LA 70148 (United States)]. E-mail: apuri@uno.edu

    2007-07-02

    In the present Letter, we simulate the propagation of binary signals in semi-infinite, mechanical chains of coupled oscillators harmonically driven at the end, by making use of the recently discovered process of nonlinear supratransmission. Our numerical results-which are based on a brand-new computational technique with energy-invariant properties-show an efficient and reliable transmission of information.

  17. Chemo-Mechanical Coupling in Curing and Material-Interphase Evolution in Multi-Constituent Materials (Preprint)

    Science.gov (United States)

    2017-09-11

    maximization of the rate of entropy production constraint, considering anisotropic effective reaction rates and the limits of diffusion- dominated...anisotropic effective reaction rates accompanied with an anisotropic tensor that provides coupling of chemical reaction and mechanical stresses. In this...a function of the reaction Γ . This function can also be developed based on the experimentally obtained density versus amine concentration plot for

  18. Tuning Monte Carlo Generators: The Perugia Tunes

    CERN Document Server

    Skands, Peter Zeiler

    2010-01-01

    We present 9 new tunes of the pT-ordered shower and underlying-event model in PYTHIA 6.4. These "Perugia" tunes update and supersede the older "S0" family. The data sets used to constrain the models include hadronic Z0 decays at LEP, Tevatron minimum-bias data at 630, 1800, and 1960 GeV, Tevatron Drell-Yan data at 1800 and 1960 GeV, and SPS min-bias data at 200, 546, and 900 GeV. In addition to the central parameter set, called "Perugia 0", we introduce a set of 8 related "Perugia Variations" that attempt to systematically explore soft, hard, parton density, and colour structure variations in the theoretical parameters. Based on these variations, a best-guess prediction of the charged track multiplicity in inelastic, nondiffractive minimum-bias events at the LHC is made. Note that these tunes can only be used with PYTHIA 6, not with PYTHIA 8. Note: this report was updated in March 2011 with a new set of variations, collectively labeled "Perugia 2011", that are optimized for matching applications and which als...

  19. TUNE: Compiler-Directed Automatic Performance Tuning

    Energy Technology Data Exchange (ETDEWEB)

    Hall, Mary [University of Utah

    2014-09-18

    This project has developed compiler-directed performance tuning technology targeting the Cray XT4 Jaguar system at Oak Ridge, which has multi-core Opteron nodes with SSE-3 SIMD extensions, and the Cray XE6 Hopper system at NERSC. To achieve this goal, we combined compiler technology for model-guided empirical optimization for memory hierarchies with SIMD code generation, which have been developed by the PIs over the past several years. We examined DOE Office of Science applications to identify performance bottlenecks and apply our system to computational kernels that operate on dense arrays. Our goal for this performance-tuning technology has been to yield hand-tuned levels of performance on DOE Office of Science computational kernels, while allowing application programmers to specify their computations at a high level without requiring manual optimization. Overall, we aim to make our technology for SIMD code generation and memory hierarchy optimization a crucial component of high-productivity Petaflops computing through a close collaboration with the scientists in national laboratories.

  20. The Model Analysis of a Complex Tuning Fork Probe and Its Application in Bimodal Atomic Force Microscopy

    Directory of Open Access Journals (Sweden)

    Zhichao Wu

    2017-01-01

    Full Text Available A new electromechanical coupling model was built to quantitatively analyze the tuning fork probes, especially the complex ones. A special feature of a novel, soft tuning fork probe, that the second eigenfrequency of the probe was insensitive to the effective force gradient, was found and used in a homemade bimodal atomic force microscopy to measure power dissipation quantitatively. By transforming the mechanical parameters to the electrical parameters, a monotonous and concise method without using phase to calculate the power dissipation was proposed.

  1. Thermal mechanically coupled finite element analysis in metal-forming processes

    NARCIS (Netherlands)

    van der Lugt, J.; Huetink, Han

    1986-01-01

    A combined Eulerian-Lagrangian finite element formulation is presented for the analysis of metal-forming, coupled with thermal effects. The procedure developed involves incrementally solving a coupled set of equations for both the displacement and the temperature. The material properties may be

  2. Robust Self Tuning Controllers

    DEFF Research Database (Denmark)

    Poulsen, Niels Kjølstad

    1985-01-01

    The present thesis concerns robustness properties of adaptive controllers. It is addressed to methods for robustifying self tuning controllers with respect to abrupt changes in the plant parameters. In the thesis an algorithm for estimating abruptly changing parameters is presented. The estimator...... has several operation modes and a detector for controlling the mode. A special self tuning controller has been developed to regulate plant with changing time delay....

  3. Aging and estrogen status: a possible endothelium-dependent vascular coupling mechanism in bone remodeling.

    Directory of Open Access Journals (Sweden)

    Rhonda D Prisby

    Full Text Available Bone loss with aging and menopause may be linked to vascular endothelial dysfunction. The purpose of the study was to determine whether putative modifications in endothelium-dependent vasodilation of the principal nutrient artery (PNA of the femur are associated with changes in trabecular bone volume (BV/TV with altered estrogen status in young (6 mon and old (24 mon female Fischer-344 rats. Animals were divided into 6 groups: 1 young intact, 2 old intact, 3 young ovariectomized (OVX, 4 old OVX, 5 young OVX plus estrogen replacement (OVX+E2, and 6 old OVX+E2. PNA endothelium-dependent vasodilation was assessed in vitro using acetylcholine. Trabecular bone volume of the distal femoral metaphysis was determined by microCT. In young rats, vasodilation was diminished by OVX and restored with estrogen replacement (intact, 82±7; OVX, 61±9; OVX+E2, 90±4%, which corresponded with similar modifications in BV/TV (intact, 28.7±1.6; OVX, 16.3±0.9; OVX+E2, 25.7±1.4%. In old animals, vasodilation was unaffected by OVX but enhanced with estrogen replacement (intact, 55±8; OVX, 59±7; OVX+E2, 92±4%. Likewise, modifications in BV/TV followed the same pattern (intact, 33.1±1.6; OVX, 34.4±3.7; OVX+E2, 42.4±2.1%. Furthermore, in old animals with low endogenous estrogen (i.e., intact and old OVX, vasodilation was correlated with BV/TV (R(2 = 0.630; P<0.001. These data demonstrate parallel effects of estrogen on vascular endothelial function and BV/TV, and provide for a possible coupling mechanism linking endothelium-dependent vasodilation to bone remodeling.

  4. Promotion of enzyme flexibility by dephosphorylation and coupling to the catalytic mechanism of a phosphohexomutase.

    Science.gov (United States)

    Lee, Yingying; Villar, Maria T; Artigues, Antonio; Beamer, Lesa J

    2014-02-21

    The enzyme phosphomannomutase/phosphoglucomutase (PMM/PGM) from Pseudomonas aeruginosa catalyzes an intramolecular phosphoryl transfer across its phosphosugar substrates, which are precursors in the synthesis of exoproducts involved in bacterial virulence. Previous structural studies of PMM/PGM have established a key role for conformational change in its multistep reaction, which requires a dramatic 180° reorientation of the intermediate within the active site. Here hydrogen-deuterium exchange by mass spectrometry and small angle x-ray scattering were used to probe the conformational flexibility of different forms of PMM/PGM in solution, including its active, phosphorylated state and the unphosphorylated state that occurs transiently during the catalytic cycle. In addition, the effects of ligand binding were assessed through use of a substrate analog. We found that both phosphorylation and binding of ligand produce significant effects on deuterium incorporation. Phosphorylation of the conserved catalytic serine has broad effects on residues in multiple domains and is supported by small angle x-ray scattering data showing that the unphosphorylated enzyme is less compact in solution. The effects of ligand binding are generally manifested near the active site cleft and at a domain interface that is a site of conformational change. These results suggest that dephosphorylation of the enzyme may play two critical functional roles: a direct role in the chemical step of phosphoryl transfer and secondly through propagation of structural flexibility. We propose a model whereby increased enzyme flexibility facilitates the reorientation of the reaction intermediate, coupling changes in structural dynamics with the unique catalytic mechanism of this enzyme.

  5. Promotion of Enzyme Flexibility by Dephosphorylation and Coupling to the Catalytic Mechanism of a Phosphohexomutase*

    Science.gov (United States)

    Lee, Yingying; Villar, Maria T.; Artigues, Antonio; Beamer, Lesa J.

    2014-01-01

    The enzyme phosphomannomutase/phosphoglucomutase (PMM/PGM) from Pseudomonas aeruginosa catalyzes an intramolecular phosphoryl transfer across its phosphosugar substrates, which are precursors in the synthesis of exoproducts involved in bacterial virulence. Previous structural studies of PMM/PGM have established a key role for conformational change in its multistep reaction, which requires a dramatic 180° reorientation of the intermediate within the active site. Here hydrogen-deuterium exchange by mass spectrometry and small angle x-ray scattering were used to probe the conformational flexibility of different forms of PMM/PGM in solution, including its active, phosphorylated state and the unphosphorylated state that occurs transiently during the catalytic cycle. In addition, the effects of ligand binding were assessed through use of a substrate analog. We found that both phosphorylation and binding of ligand produce significant effects on deuterium incorporation. Phosphorylation of the conserved catalytic serine has broad effects on residues in multiple domains and is supported by small angle x-ray scattering data showing that the unphosphorylated enzyme is less compact in solution. The effects of ligand binding are generally manifested near the active site cleft and at a domain interface that is a site of conformational change. These results suggest that dephosphorylation of the enzyme may play two critical functional roles: a direct role in the chemical step of phosphoryl transfer and secondly through propagation of structural flexibility. We propose a model whereby increased enzyme flexibility facilitates the reorientation of the reaction intermediate, coupling changes in structural dynamics with the unique catalytic mechanism of this enzyme. PMID:24403075

  6. Low-frequency, broadband vibration energy harvester using coupled oscillators and frequency up-conversion by mechanical stoppers

    Science.gov (United States)

    Dechant, Eduard; Fedulov, Feodor; Chashin, Dmitrii V.; Fetisov, Leonid Y.; Fetisov, Yuri K.; Shamonin, Mikhail

    2017-06-01

    The frequencies of ambient vibrations are often low (below 30 Hz). A broadband (3 dB bandwidth is larger than 10 Hz at an acceleration amplitude of 9.81 m s-2) vibration based energy harvester is proposed for transducing mechanical energy at such low frequencies into electrical energy. The mechanical setup converts low frequency mechanical vibrations into high frequency resonance oscillations of the transducer. This conversion is done by mechanical impacts on two mechanical stoppers. The originality of the presented design is that both low-frequency and high-frequency oscillators are permanently mechanically coupled. In the equivalent mechanical circuit, this coupling is achieved by connecting the ends of the stiff spring to both seismic masses, whereas one seismic mass (collison member) is also attached to the soft spring used as the constitutive element of a low-frequency oscillator. Further, both mechanical oscillators are not realized as conventional cantilever beams. In particular, the high frequency oscillator with the natural frequency of 340 Hz is a disc-shaped diaphragm with attached piezoelectric elements and a seismic mass. It is shown that it is possible to convert mechanical vibrations with acceleration amplitude of 9.81 m s-2 in the region between approximately 7 and 25 Hz into electrical power larger than 0.1 mW with the maximum value of 0.8 mW. A simplified mathematical model based on piecewise linear coupled oscillators shows good agreement with experimental results. The ways to enhance the performance of the harvester and improve agreement with experiments are discussed.

  7. Evaluation of a new Implicit Coupling Algorithm for the Partitioned Fluid-Structure Interaction Simulation of Bileaflet Mechanical Heart Valves

    Science.gov (United States)

    Annerel, Sebastiaan; Degroote, Joris; Claessens, Tom; Vierendeels, Jan

    2010-06-01

    We present a newly developed Fluid-Structure Interaction coupling algorithm to simulate Bileaflet Mechanical Heart Valves dynamics in a partitioned way. The coupling iterations between the flow solver and the leaflet motion solver are accelerated by using the Jacobian with the derivatives of the pressure and viscous moments acting on the leaflets with respect to the leaflet acceleration. This Jacobian is used in the leaflet motion solver when new positions of the leaflets are computed during the coupling iterations. The Jacobian is numerically derived from the flow solver by applying leaflet perturbations. Instead of calculating this Jacobian every time step, the Jacobian is extrapolated from previous time steps and a recalculation of the Jacobian is only done when needed. The efficiency of our new algorithm is subsequently compared to existing algorithms which use fixed relaxation and dynamic Aitken Δ2 relaxation in the coupling iterations when the new positions of the leaflets are computed. Results show that dynamic Aitken Δ2 relaxation outperforms fixed relaxation. Moreover, during the opening phase of the valve, our new algorithm needs fewer subiterations per time step to achieve convergence than the method with Aitken Δ2 relaxation. Thus, our newly developed FSI coupling scheme outperforms the existing coupling schemes.

  8. Functional characterization of spectral tuning mechanisms in the great bowerbird short-wavelength sensitive visual pigment (SWS1), and the origins of UV/violet vision in passerines and parrots.

    Science.gov (United States)

    van Hazel, Ilke; Sabouhanian, Amir; Day, Lainy; Endler, John A; Chang, Belinda S W

    2013-11-13

    One of the most striking features of avian vision is the variation in spectral sensitivity of the short wavelength sensitive (SWS1) opsins, which can be divided into two sub-types: violet- and UV- sensitive (VS & UVS). In birds, UVS has been found in both passerines and parrots, groups that were recently shown to be sister orders. While all parrots are thought to be UVS, recent evidence suggests some passerine lineages may also be VS. The great bowerbird (Chlamydera nuchalis) is a passerine notable for its courtship behaviours in which males build and decorate elaborate bower structures. The great bowerbird SWS1 sequence possesses an unusual residue combination at known spectral tuning sites that has not been previously investigated in mutagenesis experiments. In this study, the SWS1 opsin of C. nuchalis was expressed along with a series of spectral tuning mutants and ancestral passerine SWS1 pigments, allowing us to investigate spectral tuning mechanisms and explore the evolution of UV/violet sensitivity in early passerines and parrots. The expressed C. nuchalis SWS1 opsin was found to be a VS pigment, with a λmax of 403 nm. Bowerbird SWS1 mutants C86F, S90C, and C86S/S90C all shifted λmax into the UV, whereas C86S had no effect. Experimentally recreated ancestral passerine and parrot/passerine SWS1 pigments were both found to be VS, indicating that UV sensitivity evolved independently in passerines and parrots from a VS ancestor. Our mutagenesis studies indicate that spectral tuning in C. nuchalis is mediated by mechanisms similar to those of other birds. Interestingly, our ancestral sequence reconstructions of SWS1 in landbird evolution suggest multiple transitions from VS to UVS, but no instances of the reverse. Our results not only provide a more precise prediction of where these spectral sensitivity shifts occurred, but also confirm the hypothesis that birds are an unusual exception among vertebrates where some descendants re-evolved UVS from a violet type

  9. Mechanical performance experiments on rock and cement, casing residual stress evaluation in the thermal recovery well based on thermal-structure coupling

    National Research Council Canada - National Science Library

    Chen, Yong; Peng, Xu; Yu, Hao

    2017-01-01

    .... In this paper, mechanical performance experiments on rock and cement are carried out first, and then a finite element mechanical model of thermal recovery wellbore based on thermal-structure coupling is established...

  10. Facile synthesis of nano-sized CuFe2S3: morphology and diverse functional tuning and crystal growth mechanism exploring

    Science.gov (United States)

    Zhang, Xiao; Zhao, Huan; Zhu, Yuda; Yang, You; Jiang, Dongli; Chen, Xiaoqin; Sun, Jing; Luo, Jiaoming

    2017-01-01

    Abstract Ternary chalcogenide compounds are such promising and have been used for much practical applications. As a sort of these compounds, cubanite (CuFe2S3) possess some unique properties which can be used in different fields. In our study, we developed a facile one pot synthesis of CuFe2S3 nanocrystals (NCs) at a low reaction temperature, and achieved a morphology and phase composition tuning of the NCs through changing a variety of precursors and surfactants, meanwhile improved their magnetism and optical properties. Eventually, well-ordered and ‘nano-brick’ like CuFe2S3 NCs were obtained and showed best magnetism and near-infrared fluorescence properties. Furthermore, the NCs were proved with good biocompatibility and possibility for cell labeling. This kind of materials with lower toxicity and potential of magnetic is bound to remedy the defects of photoluminescence quantum dots (QDs) and be with higher potential in the field of biological diagnosis and multi-functional system construction. PMID:28798868

  11. Asymmetrically coupled resonators for mass sensing

    Science.gov (United States)

    Marquez, S.; Alvarez, M.; Plaza, J. A.; Villanueva, L. G.; Dominguez, C.; Lechuga, L. M.

    2017-09-01

    Mechanically coupled resonators have been applied in the last years to the development of nanomechanical mass-sensors based on the detection of the different vibration modes of the system by measuring on a single resonator. Their sensitivity and capability for detecting multiple analytes strongly depends on the design and coupling strength between the mechanically coupled resonators in an array format. We present a theoretical and experimental study of the behavior of an asymmetrically coupled array of four different resonators. These doubly clamped beam resonators are elastically coupled by an overhang region of varying length along the transversal axis of the array. The results show that parameters such as the gap between microbeams and the overhang length affect the coupling strength, tuning the system from highly disordered and highly localized (weak coupling) to highly delocalized (strong coupling). In the strong coupling and partially localized case, the distances between resonant peaks are larger, reaching higher eigenfrequency values. In this case, relative changes in a specific eigenstate, due to an added mass, can be markedly large due to the energy distribution over a single microbeam. A strong coupling also facilitates performing the detection on the relative frequency shift mode, which can usually be resolved with better precision than the amplitude changes.

  12. Coupled thermo-hydro-mechanical experiment at Kamaishi mine. Technical note 15-99-02. Experimental results

    Energy Technology Data Exchange (ETDEWEB)

    Chijimatsu, Masakazu; Sugita, Yutaka; Fujita, Tomoo [Tokai Works, Waste Management and Fuel Cycle Research Center, Waste Isolation Research Division, Barrier Performance Group, Japan Nuclear Cycle Development Inst., Tokai, Ibaraki (Japan); Amemiya, Kiyoshi [Hazama Corp., Tokyo (Japan)

    1999-07-01

    It is an important part of the near field performance assessment of nuclear waste disposal to evaluate coupled thermo-hydro-mechanical (T-H-M) phenomena, e.g., thermal effects on groundwater flow through rock matrix and water seepage into the buffer material, the generation of swelling pressure of the buffer material, and thermal stresses potentially affecting porosity and fracture apertures of the rock. An in-situ T-H-M experiment named Engineered Barrier Experiment' has been conducted at the Kamaishi Mine, of which host rock is granodiorite, in order to establish conceptual models of the coupled T-H-M processes and to build confidence in mathematical and computer codes. In 1995, fourteen boreholes were excavated in order to install the various sensors. After the hydraulic tests, mechanical tests were carried out to obtain the rock properties. After that, a test pit, 1.7 m in diameter and 5.0 m in depth, was excavated. During the excavation, the change of pore pressure, displacement and temperature of rock mass were measured. In 1996, the buffer material and heater were set up in the test pit, and then coupled thermo-hydro-mechanical test was started. The duration of heating phase was 250 days and that of cooling phase was 180 days. The heater surface was controlled to be 100degC during heating phase. Measurement was carried out by a number of sensors installed in both buffer and rock mass during the test. The field experiment leads to a better understanding of the behavior of the coupled thermo-hydro-mechanical phenomena in the near field. (author)

  13. Coupled DDD-FEM modeling on the mechanical behavior of microlayered metallic multilayer film at elevated temperature

    Science.gov (United States)

    Huang, Minsheng; Li, Zhenhuan

    2015-12-01

    To investigate the mechanical behavior of the microlayered metallic thin films (MMMFs) at elevated temperature, an enhanced discrete-continuous model (DCM), which couples rather than superposes the two-dimensional climb/glide-enabled discrete dislocation dynamics (2D-DDD) with the linearly elastic finite element method (FEM), is developed in this study. In the present coupling scheme, two especial treatments are made. One is to solve how the plastic strain captured by the DDD module is transferred properly to the FEM module as an eigen-strain; the other is to answer how the stress field computationally obtained by the FEM module is transferred accurately to the DDD module to drive those discrete dislocations moving correctly. With these two especial treatments, the interactions between adjacent dislocations and between dislocation pile-ups and inter-phase boundaries (IBs), which are crucial to the strengthening effect in MMMFs, are carefully taken into account. After verified by comparing the computationally predicted results with the theoretical solutions for a dislocation residing in a homogeneous material and nearby a bi-material interface, this 2D-DDD/FEM coupling scheme is used to model the tensile mechanical behaviors of MMMFs at elevated temperature. The strengthening mechanism of MMMFs and the layer thickness effect are studied in detail, with special attentions to the influence of dislocation climb on them.

  14. Simulation of the Mechanical Response of the 11T Magnet by Means of COMSOL-MpCCI-ANSYS Coupling

    CERN Document Server

    Wilczek, Michal

    2017-01-01

    This report covers the work during my Summer Student internship at CERN as a part of the STEAM group (Simulation of Transient Effects in Accelerator Magnets) in the Technology Department, Machine Protection and Electrical Integrity group. I was responsible for the development of the ANSYS APDL model of the 11T superconducting magnet serving as a proof of concept for magneto-thermo-mechanical co-simulations of quench propagation in COMSOL and ANSYS software. The aforementioned co-simulation estimates the magnetic, thermal, and mechanical response of the magnet during the discharge process, while protected by a recently developed method, called Coupling-Loss Induced Quench (CLIQ). The already existing STEAM framework performs field/circuit coupling of a magneto-thermal field models previously developed by the STEAM. The next task of the group aimed at combining magneto-thermal field solution with the mechanical simulations. Such a coupling is of interest for the High-Luminosity upgrade of the Large Hadron Colli...

  15. Linking Behavioral and Neurophysiological Indicators of Perceptual Tuning to Language

    Directory of Open Access Journals (Sweden)

    Eswen eFava

    2011-08-01

    Full Text Available Little is known about the neural mechanisms that underlie tuning to the native language(s in early infancy. Here we review language tuning through the lens of language experience and introduce a new manner in which to conceptualize the phenomenon of language tuning: the relative speed of tuning hypothesis. This hypothesis has as its goal a characterization of the unique time course of the tuning process, given the different components (e.g., phonology, prosody, syntax, semantics of one or more languages as they become available to infants. In this review, we first examine the established behavioral findings and integrate more recent neurophysiological data on neonatal development, which together demonstrate evidence of early language tuning given differential language exposure in utero. Next, we examine traditional accounts of sensitive and critical periods to determine how these constructs complement current data on the neural mechanisms underlying language tuning. We then synthesize the extant infant behavioral and imaging literatures on monolingual, bilingual, and sensory deprived tuning experience, thereby scrutinizing the effect of these three different language profiles on the specific timing, progression, and outcomes of language tuning. Finally, we discuss future directions researchers might pursue on this aspect of development, advocating our relative speed of tuning hypothesis as a useful framework for conceptualizing the complex process by which language experience shapes language sensitivity.

  16. Complier-Directed Automatic Performance Tuning (TUNE) Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Chame, Jacqueline [USC-ISI

    2013-06-07

    TUNE was created to develop compiler-directed performance tuning technology targeting the Cray XT4 system at Oak Ridge. TUNE combines compiler technology for model-guided empirical optimization for memory hierarchies with SIMD code generation. The goal of this performance-tuning technology is to yield hand-tuned levels of performance on DOE Office of Science computational kernels, while allowing application programmers to specify their computations at a high level without requiring manual optimization. Overall, TUNE aims to make compiler technology for SIMD code generation and memory hierarchy optimization a crucial component of high-productivity Petaflops computing through a close collaboration with the scientists in national laboratories.

  17. Final Report: Improving the understanding of the coupled thermal-mechanical-hydrologic behavior of consolidating granular salt

    Energy Technology Data Exchange (ETDEWEB)

    Stormont, John [Univ. of New Mexico, Albuquerque, NM (United States); Lampe, Brandon [Univ. of New Mexico, Albuquerque, NM (United States); Mills, Melissa [Univ. of New Mexico, Albuquerque, NM (United States); Paneru, Laxmi [Univ. of New Mexico, Albuquerque, NM (United States); Lynn, Timothy [Univ. of New Mexico, Albuquerque, NM (United States); Piya, Aayush [Univ. of New Mexico, Albuquerque, NM (United States)

    2017-09-09

    The goal of this project is to improve the understanding of key aspects of the coupled thermal-mechanical-hydrologic response of granular (or crushed) salt used as a seal material for shafts, drifts, and boreholes in mined repositories in salt. The project is organized into three tasks to accomplish this goal: laboratory measurements of granular salt consolidation (Task 1), microstructural observations on consolidated samples (Task 2), and constitutive model development and evaluation (Task 3). Task 1 involves laboratory measurements of salt consolidation along with thermal properties and permeability measurements conducted under a range of temperatures and stresses expected for potential mined repositories in salt. Testing focused on the role of moisture, temperature and stress state on the hydrologic (permeability) and thermal properties of consolidating granular salt at high fractional densities. Task 2 consists of microstructural observations made on samples after they have been consolidated to interpret deformation mechanisms and evaluate the ability of the constitutive model to predict operative mechanisms under different conditions. Task 3 concerns the development of the coupled thermal-mechanical-hydrologic constitutive model for granular salt consolidation. The measurements and observations in Tasks 1 and 2 were used to develop a thermal-mechanical constitutive model. Accomplishments and status from each of these efforts is reported in subsequent sections of this report

  18. Dynamics of coupled vibration modes in a quantum non-linear mechanical resonator

    NARCIS (Netherlands)

    Labadze, G.; Dukalski, M.S.; Blanter, Y.M.

    2016-01-01

    We investigate the behaviour of two non-linearly coupled flexural modes of a doubly clamped suspended beam (nanomechanical resonator). One of the modes is externally driven. We demonstrate that classically, the behavior of the non-driven mode is reminiscent of that of a parametrically driven

  19. New functions and signaling mechanisms for the class of adhesion G protein-coupled receptors

    NARCIS (Netherlands)

    Liebscher, Ines; Ackley, Brian; Araç, Demet; Ariestanti, Donna M.; Aust, Gabriela; Bae, Byoung-Il; Bista, Bigyan R.; Bridges, James P.; Duman, Joseph G.; Engel, Felix B.; Giera, Stefanie; Goffinet, André M.; Hall, Randy A.; Hamann, Jörg; Hartmann, Nicole; Lin, Hsi-Hsien; Liu, Mingyao; Luo, Rong; Mogha, Amit; Monk, Kelly R.; Peeters, Miriam C.; Prömel, Simone; Ressl, Susanne; Schiöth, Helgi B.; Sigoillot, Séverine M.; Song, Helen; Talbot, William S.; Tall, Gregory G.; White, James P.; Wolfrum, Uwe; Xu, Lei; Piao, Xianhua

    2014-01-01

    The class of adhesion G protein-coupled receptors (aGPCRs), with 33 human homologs, is the second largest family of GPCRs. In addition to a seven-transmembrane alpha-helix-a structural feature of all GPCRs-the class of aGPCRs is characterized by the presence of a large N-terminal extracellular

  20. Hydro-mechanical coupled simulation of hydraulic fracturing using the eXtended Finite Element Method (XFEM)

    Science.gov (United States)

    Youn, Dong Joon

    This thesis presents the development and validation of an advanced hydro-mechanical coupled finite element program analyzing hydraulic fracture propagation within unconventional hydrocarbon formations under various conditions. The realistic modeling of hydraulic fracturing is necessarily required to improve the understanding and efficiency of the stimulation technique. Such modeling remains highly challenging, however, due to factors including the complexity of fracture propagation mechanisms, the coupled behavior of fracture displacement and fluid pressure, the interactions between pre-existing natural and initiated hydraulic fractures and the formation heterogeneity of the target reservoir. In this research, an eXtended Finite Element Method (XFEM) scheme is developed allowing for representation of single or multiple fracture propagations without any need for re-meshing. Also, the coupled flows through the fracture are considered in the program to account for their influence on stresses and deformations along the hydraulic fracture. In this research, a sequential coupling scheme is applied to estimate fracture aperture and fluid pressure with the XFEM. Later, the coupled XFEM program is used to estimate wellbore bottomhole pressure during fracture propagation, and the pressure variations are analyzed to determine the geometry and performance of the hydraulic fracturing as pressure leak-off test. Finally, material heterogeneity is included into the XFEM program to check the effect of random formation property distributions to the hydraulic fracture geometry. Random field theory is used to create the random realization of the material heterogeneity with the consideration of mean, standard deviation, and property correlation length. These analyses lead to probabilistic information on the response of unconventional reservoirs and offer a more scientific approach regarding risk management for the unconventional reservoir stimulation. The new stochastic approach

  1. Coupled simulation of CFD-flight-mechanics with a two-species-gas-model for the hot rocket staging

    Science.gov (United States)

    Li, Yi; Reimann, Bodo; Eggers, Thino

    2016-11-01

    The hot rocket staging is to separate the lowest stage by directly ignite the continuing-stage-motor. During the hot staging, the rocket stages move in a harsh dynamic environment. In this work, the hot staging dynamics of a multistage rocket is studied using the coupled simulation of Computational Fluid Dynamics and Flight Mechanics. Plume modeling is crucial for a coupled simulation with high fidelity. A 2-species-gas model is proposed to simulate the flow system of the rocket during the staging: the free-stream is modeled as "cold air" and the exhausted plume from the continuing-stage-motor is modeled with an equivalent calorically-perfect-gas that approximates the properties of the plume at the nozzle exit. This gas model can well comprise between the computation accuracy and efficiency. In the coupled simulations, the Navier-Stokes equations are time-accurately solved in moving system, with which the Flight Mechanics equations can be fully coupled. The Chimera mesh technique is utilized to deal with the relative motions of the separated stages. A few representative staging cases with different initial flight conditions of the rocket are studied with the coupled simulation. The torque led by the plume-induced-flow-separation at the aft-wall of the continuing-stage is captured during the staging, which can assist the design of the controller of the rocket. With the increasing of the initial angle-of-attack of the rocket, the staging quality becomes evidently poorer, but the separated stages are generally stable when the initial angle-of-attack of the rocket is small.

  2. Surface micromachined tunable 1.55 μm-VCSEL with 102 nm continuous single-mode tuning.

    Science.gov (United States)

    Gierl, C; Gruendl, T; Debernardi, P; Zogal, K; Grasse, C; Davani, H A; Böhm, G; Jatta, S; Küppers, F; Meissner, P; Amann, M-C

    2011-08-29

    For the first time a vertical-cavity surface-emitting laser (VCSEL) with a single-mode wavelength-tuning over 102 nm in the range of 1550 nm is demonstrated. The fiber-coupled optical output power has a maximum of 3.5 mW and is > 2 mW over the entire tuning range. The sidemode suppression ratios are > 45 dB. The wavelength tuning is achieved with the micro-electro mechanical actuation of a mirror membrane fabricated with surface micro-machining for on-wafer mass production. The mirror membrane consists of low cost dielectric materials (SiOx/SiNy) deposited with low temperature (< 100°C) Plasma Enhanced Chemical Vapor Deposition (PECVD).

  3. Fine-tuning with brane-localized flux in 6D supergravity

    Energy Technology Data Exchange (ETDEWEB)

    Niedermann, Florian; Schneider, Robert [Arnold Sommerfeld Center for Theoretical Physics, Ludwig-Maximilians-Universität,Theresienstraße 37, 80333 Munich (Germany); Excellence Cluster Universe,Boltzmannstraße 2, 85748 Garching (Germany)

    2016-02-03

    There are claims in the literature that the cosmological constant problem could be solved in a braneworld model with two large (micron-sized) supersymmetric extra dimensions. The mechanism relies on two basic ingredients: first, the cosmological constant only curves the compact bulk geometry into a rugby shape while the 4D curvature stays flat. Second, a brane-localized flux term is introduced in order to circumvent Weinberg’s fine-tuning argument, which otherwise enters here through a backdoor via the flux quantization condition. In this paper, we show that the latter mechanism does not work in the way it was designed: the only localized flux coupling that guarantees a flat on-brane geometry is one which preserves the scale invariance of the bulk theory. Consequently, Weinberg’s argument applies, making a fine-tuning necessary again. The only remaining window of opportunity lies within scale invariance breaking brane couplings, for which the tuning could be avoided. Whether the corresponding 4D curvature could be kept under control and in agreement with the observed value will be answered in our companion paper http://arxiv.org/abs/1512.03800.

  4. Fine-tuning with brane-localized flux in 6D supergravity

    Science.gov (United States)

    Niedermann, Florian; Schneider, Robert

    2016-02-01

    There are claims in the literature that the cosmological constant problem could be solved in a braneworld model with two large (micron-sized) supersymmetric extra dimensions. The mechanism relies on two basic ingredients: first, the cosmological constant only curves the compact bulk geometry into a rugby shape while the 4D curvature stays flat. Second, a brane-localized flux term is introduced in order to circumvent Weinberg's fine-tuning argument, which otherwise enters here through a backdoor via the flux quantization condition. In this paper, we show that the latter mechanism does not work in the way it was designed: the only localized flux coupling that guarantees a flat on-brane geometry is one which preserves the scale invariance of the bulk theory. Consequently, Weinberg's argument applies, making a fine-tuning necessary again. The only remaining window of opportunity lies within scale invariance breaking brane couplings, for which the tuning could be avoided. Whether the corresponding 4D curvature could be kept under control and in agreement with the observed value will be answered in our companion paper [1].

  5. Optimal elastic coupling in form of one mechanical spring to improve energy efficiency of walking bipedal robots

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, Fabian; Römer, Ulrich, E-mail: ulrich.roemer@kit.edu; Fidlin, Alexander; Seemann, Wolfgang [Institute of Engineering Mechanics, Karlsruhe Institute of Technology (Germany)

    2016-11-15

    This paper presents a method to optimize the energy efficiency of walking bipedal robots by more than 80 % in a speed range from 0.3 to 2.3 m/s using elastic couplings—mechanical springs with movement speed independent parameters. The considered planar robot consists of a trunk, two two-segmented legs, two actuators in the hip joints, two actuators in the knee joints and an elastic coupling between the shanks. It is modeled as underactuated system to make use of its natural dynamics and feedback controlled via input–output linearization. A numerical optimization of the joint angle trajectories as well as the elastic couplings is performed to minimize the average energy expenditure over the whole speed range. The elastic couplings increase the swing leg motion’s natural frequency thus making smaller steps more efficient which reduce the impact loss at the touchdown of the swing leg. The process of energy turnover is investigated in detail for the robot with and without elastic coupling between the shanks. Furthermore, the influences of the elastic couplings’ topology and of joint friction are analyzed. It is shown that the optimization of the robot’s motion and elastic coupling towards energy efficiency leads to a slightly slower convergence rate of the controller, yet no loss of stability, but a lower sensitivity with respect to disturbances. The optimal elastic coupling discovered via numerical optimization is a linear torsion spring with transmissions between the shanks. A design proposal for this elastic coupling—which does not affect the robot’s trunk and parallel shank motion and can be used to enhance an existing robot—is given for planar as well as spatial robots.

  6. Polypropylene/Short Glass Fibers Composites: Effects of Coupling Agents on Mechanical Properties, Thermal Behaviors, and Morphology

    Directory of Open Access Journals (Sweden)

    Jia-Horng Lin

    2015-12-01

    Full Text Available This study uses the melt compounding method to produce polypropylene (PP/short glass fibers (SGF composites. PP serves as matrix while SGF serves as reinforcement. Two coupling agents, maleic anhydride grafted polypropylene, (PP-g-MA and maleic anhydride grafted styrene-ethylene-butylene-styrene block copolymer (SEBS-g-MA are incorporated in the PP/SGF composites during the compounding process, in order to improve the interfacial adhesion and create diverse desired properties of the composites. According to the mechanical property evaluations, increasing PP-g-MA as a coupling agent provides the composites with higher tensile, flexural, and impact properties. In contrast, increasing SEBS-g-MA as a coupling agent provides the composites with decreasing tensile and flexural strengths, but also increasing impact strength. The DSC results indicate that using either PP-g-MA or SEBS-g-MA as the coupling agent increases the crystallization temperature. However, the melting temperature of PP barely changes. The spherulitic morphology results show that PP has a smaller spherulite size when it is processed with PP-g-MA or SEBS-g-MA as the coupling agent. The SEM results indicate that SGF is evenly distributed in PP matrices, but there are distinct voids between these two materials, indicating a poor interfacial adhesion. After PP-g-MA or SEBS-g-MA is incorporated, SGF can be encapsulated by PP, and the voids between them are fewer and indistinctive. This indicates that the coupling agents can effectively improve the interfacial compatibility between PP and SGF, and as a result improves the diverse properties of PP/SGF composites.

  7. SC tuning fork

    CERN Multimedia

    The tuning fork used to modulate the radiofrequency system of the synchro cyclotron (SC) from 1957 to 1973. This piece is an unused spare part. The SC was the 1st accelerator built at CERN. It operated from August 1957 until it was closed down at the end of 1990. In the SC the magnetic field did not change with time, and the particles were accelerated in successive pulses by a radiofrequency voltage of some 20kV which varied in frequency as they spiraled outwards towards the extraction radius. The frequency varied from 30MHz to about 17Mz in each pulse. The tuning fork vibrated at 55MHz in vacuum in an enclosure which formed a variable capacitor in the tuning circuit of the RF system, allowing the RF to vary over the appropriate range to accelerate protons from the centre of the macine up to 600Mev at extraction radius. In operation the tips of the tuning fork blade had an amplitude of movement of over 1 cm. The SC accelerator underwent extensive improvements from 1973 to 1975, including the installation of a...

  8. Tuning with Triangles

    Science.gov (United States)

    Harkleroad, Leon

    2008-01-01

    This paper examines three historical geometric constructions for handcrafting stringed instruments. Using elementary geometry--in particular, triangles--these methods can provide quite good rational approximations to the irrationals that arise from tuning instruments in equal temperament. Interestingly, continued fractions help explain the…

  9. Planck-LFI radiometers tuning

    Energy Technology Data Exchange (ETDEWEB)

    Cuttaia, F; Stringhetti, L; Terenzi, L; Villa, F; Butler, R C; Franceschi, E [Istituto di Astrofisica Spaziale e Fisica Cosmica, INAF, via P. Gobetti 101, 40129 Bologna (Italy); Mennella, A; Tomasi, M; Bersanelli, M; Cappellini, B; Franceschet, C; Hoyland, R [Universita degli Studi di Milano, via Celoria 16, 20133 Milano (Italy); Maris, M; Frailis, M [INAF / OATS, via Tiepolo 11, 34143 Trieste (Italy); Cuevas, L P [Research and Scientific Support Department of ESA, ESTEC, Noordwijk (Netherlands); D' Arcangelo, O [IFP-CNR, via Cozzi 53, 20013 Milano (Italy); Davis, R; Lowe, S [Jodrell Bank Centre for Astrophysics, Alan Turing Building, The University of Manchester, Manchester, M13 9PL (United Kingdom); Gregorio, A [University of Trieste, Department of Physics, via Valerio 2, 34127 Trieste (Italy); Leonardi, R, E-mail: cuttaia@iasfbo.inaf.i [Department of Physics, University of California, Santa Barbara, CA 93106-9530 (United States)

    2009-12-15

    This paper describes the Planck Low Frequency Instrument tuning activities performed through the ground test campaigns, from Unit to Satellite Levels. Tuning is key to achieve the best possible instrument performance and tuning parameters strongly depend on thermal and electrical conditions. For this reason tuning has been repeated several times during ground tests and it has been repeated in flight before starting nominal operations. The paper discusses the tuning philosophy, the activities and the obtained results, highlighting developments and changes occurred during test campaigns. The paper concludes with an overview of tuning performed during the satellite cryogenic test campaign (Summer 2008) and of the plans for the just started in-flight calibration.

  10. Electromagnetic dynamic response of HL-2M vacuum vessel under plasma disruption considering the electromagneto-mechanical coupling effect

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Hongwei; Yuan, Zhensheng; Li, Weixin; Pei, Cuixiang; Xie, Shejuan [State Key Laboratory for Strength and Vibration of Mechanical Structures, Shaanxi Engineering Research Center for NDT and Structural Integrity Evaluation, Xi’an Jiaotong University, Xi’an 710049 (China); Chen, Zhenmao, E-mail: chenzm@mail.xjtu.edu.cn [State Key Laboratory for Strength and Vibration of Mechanical Structures, Shaanxi Engineering Research Center for NDT and Structural Integrity Evaluation, Xi’an Jiaotong University, Xi’an 710049 (China); Pan, Yudong; Cai, Lijun; Li, Jiaxian [Southwestern Institute of Physics, Chengdu 610041 (China)

    2016-11-01

    Highlights: • A 1/5 numerical model is established and validated for HL-2M vacuum vessel. • The Lagrangian approach used for treating the EM-mechanical coupling problem is introduced. • The EM field and structural dynamic response of HL-2M VV during plasma disruptions are simulated by using the Lagrangian strategy. • The dynamic responses of the VV of HL-2M are compared to clarify the effect of the EM-mechanical coupling under the MD and VED conditions. • The results present a basis for the safe operation of the HL-2M VV device. - Abstract: During plasma disruptions (PDs), transient eddy currents are induced in the HL-2M vacuum vessel (VV) which is a D-shaped, double thin-wall structure. Under the circumstance of high magnetic field, the resulting electromagnetic (EM) forces during PDs are large and the dynamic response of related structures may be violent. In this complicated EM circumstance, the EM-mechanical coupling effect may also have a great influence on the dynamic response of VV structure. In this paper, the EM field and structural dynamic response of HL-2M VV during PDs are simulated by adopting a numerical code of the Lagrangian approach. The Lagrangian approach is on the basis of the Maxwell equations in the Lagrangian description, which treats the coupling behavior of magnetic damping effect without explicitly using the velocity term. This approach can be easily applied to actual structures by updating FEM meshes and reforming coefficient matrices before calculating EM field at each time step. In this work, the disruption plasma currents of operating conditions are simulated by using the DINA code and then the dynamic responses of displacements and stresses of the VV of HL-2M are obtained for both cases with and without considering the coupling effect. The numerical results show that stresses under the disruptions (MD and VDE) are not significant and the coupling effect does not significantly affect the peak dynamic response for the HL-2M

  11. Electromagneto-mechanical coupling analysis of a test module in J-TEXT Tokamak during plasma disruption

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Haijie; Yuan, Zhensheng; Yuan, Hongwei; Pei, Cuixiang [State Key Laboratory for Strength and Vibration of Mechanical Structures, Shanxi Engineering Research Center for NDT and Structural Integrity Evaluation Xi’an Jiaotong University, Xi’an 710049 (China); Chen, Zhenmao, E-mail: chenzm@mail.xjtu.edu.cn [State Key Laboratory for Strength and Vibration of Mechanical Structures, Shanxi Engineering Research Center for NDT and Structural Integrity Evaluation Xi’an Jiaotong University, Xi’an 710049 (China); Yang, Jinhong; Wang, Weihua [Institute of Applied Physics of AOA, Hefei 230031 (China)

    2016-11-01

    In this paper, the dynamic response during plasma disruption of a test blanket module in vacuum vessel (VV) of the Joint TEXT (J-TEXT), which is an experimental Tokamak device with iron core, was simulated by applying a program developed by authors on the ANSYS platform using its parametric design language (APDL). The moving coordinate method as well as the load transfer and sequential coupling strategy were adopted to cope with the electromagneto-mechanical coupling effect. To establish the numerical model, the influence of the iron core on the eddy current and electromagnetic (EM) force during disruption was numerically investigated at first and the influence was found not significant. Together with the geometrical features of the J-TEXT Tokamak structure, 180° sector models without magnetic core were finally established for the EM field and the structural response simulations. To obtain the source plasma current, the plasma current evolution during disruption was simulated by using the Tokamak Simulation Code (TSC). With the numerical models and the source plasma current, the dynamic response of both the VV structure and the test module were calculated. The numerical results show that the maximum stress of the test module is in safe range, and the magnetic damping effect can weaken vibration of the test module. In addition, simulation without considering the coupling effect was carried out, which shows that the influence of coupling effect is not significant for the peak stress of the J-TEXT disruption problem.

  12. Cytocompatibility and Mechanical Properties of Short Phosphate Glass Fibre Reinforced Polylactic Acid (PLA) Composites: Effect of Coupling Agent Mediated Interface

    Science.gov (United States)

    Hasan, Muhammad Sami; Ahmed, Ifty; Parsons, Andrew; Walker, Gavin; Scotchford, Colin

    2012-01-01

    In this study three chemical agents Amino-propyl-triethoxy-silane (APS), sorbitol ended PLA oligomer (SPLA) and Hexamethylene diisocyanate (HDI) were identified to be used as coupling agents to react with the phosphate glass fibre (PGF) reinforcement and the polylactic acid (PLA) polymer matrix of the composite. Composites were prepared with short chopped strand fibres (l = 20 mm, ϕ = 20 µm) in a random arrangement within PLA matrix. Improved, initial composite flexural strength (~20 MPa) was observed for APS treated fibres, which was suggested to be due to enhanced bonding between the fibres and polymer matrix. Both APS and HDI treated fibres were suggested to be covalently linked with the PLA matrix. The hydrophobicity induced by these coupling agents (HDI, APS) helped to resist hydrolysis of the interface and thus retained their mechanical properties for an extended period of time as compared to non-treated control. Approximately 70% of initial strength and 65% of initial modulus was retained by HDI treated fibre composites in contrast to the control, where only ~50% of strength and modulus was retained after 28 days of immersion in PBS at 37 °C. All coupling agent treated and control composites demonstrated good cytocompatibility which was comparable to the tissue culture polystyrene (TCP) control, supporting the use of these materials as coupling agent’s within medical implant devices. PMID:24955744

  13. TOUGH2-seed: A coupled fluid flow and mechanical-stochastic approach to model injection-induced seismicity

    Science.gov (United States)

    Rinaldi, Antonio P.; Nespoli, Massimo

    2017-11-01

    Understanding the injection-induced triggering mechanism is a fundamental step towards controlling the seismicity generated by deep underground exploitation. Here we propose a modeling approach based on coupling the TOUGH2 simulator with a geomechanical-stochastic model. The hydro-mechanical-stochastic model provides a good representation of different mechanisms influencing each other during and after the injection phase. Each mechanism affects the induced seismicity in a different way and at different times during the reservoir stimulation, confirming that a complex interaction is in place, and that more sophisticated and physics-based approaches coupled with statistical model are required to explain such a complex interaction. In addition to previous statistical and hybrid models, our approach accounts for a full 3D formulation of both stresses and fluid flow, further including all the TOUGH2 capabilities. Furthermore, it includes interactions between triggered seismic events through calculation of static stress transfer. In this work, we present the main capabilities of TOUGH2-SEED and apply the model to the Basel EGS case, successfully reproducing the injection pressure as well as the evolution of the seismicity.

  14. A morphing strategy to couple non-local to local continuum mechanics

    KAUST Repository

    Lubineau, Gilles

    2012-06-01

    A method for coupling non-local continuum models with long-range central forces to local continuum models is proposed. First, a single unified model that encompasses both local and non-local continuum representations is introduced. This model can be purely non-local, purely local or a hybrid depending on the constitutive parameters. Then, the coupling between the non-local and local descriptions is performed through a transition (morphing) affecting only the constitutive parameters. An important feature is the definition of the morphing functions, which relies on energy equivalence. This approach is useful in large-scale modeling of materials that exhibit strong non-local effects. The computational cost can be reduced while maintaining a reasonable level of accuracy. Efficiency, robustness and basic properties of the approach are discussed using one- and two-dimensional examples. © 2012 Elsevier Ltd.

  15. Receptor recruitment: A mechanism for interactions between G protein-coupled receptors

    OpenAIRE

    Holtbäck, Ulla; Brismar, Hjalmar; DiBona, Gerald F.; Fu, Michael; Greengard, Paul; Aperia, Anita

    1999-01-01

    There is a great deal of evidence for synergistic interactions between G protein-coupled signal transduction pathways in various tissues. As two specific examples, the potent effects of the biogenic amines norepinephrine and dopamine on sodium transporters and natriuresis can be modulated by neuropeptide Y and atrial natriuretic peptide, respectively. Here, we report, using a renal epithelial cell line, that both types of modulation involve recruitment of receptors from the interior of the ce...

  16. A Molecular Mechanism for Sequential Activation of a G Protein-Coupled Receptor

    DEFF Research Database (Denmark)

    Grundmann, Manuel; Tikhonova, Irina G; Hudson, Brian D

    2016-01-01

    Ligands targeting G protein-coupled receptors (GPCRs) are currently classified as either orthosteric, allosteric, or dualsteric/bitopic. Here, we introduce a new pharmacological concept for GPCR functional modulation: sequential receptor activation. A hallmark feature of this is a stepwise ligand...... and pharmacological perturbations along with computational methods, and propose a kinetic model applicable to the analysis of sequential receptor activation. We envision this form of dynamic agonism as a common principle of nature to spatiotemporally encode cellular information....

  17. Coupled hydro-thermo-mechanical modeling of hydraulic fracturing in quasi-brittle rocks using BPM-DEM

    Directory of Open Access Journals (Sweden)

    Ingrid Tomac

    2017-02-01

    Full Text Available This paper presents an improved understanding of coupled hydro-thermo-mechanical (HTM hydraulic fracturing of quasi-brittle rock using the bonded particle model (BPM within the discrete element method (DEM. BPM has been recently extended by the authors to account for coupled convective–conductive heat flow and transport, and to enable full hydro-thermal fluid–solid coupled modeling. The application of the work is on enhanced geothermal systems (EGSs, and hydraulic fracturing of hot dry rock (HDR is studied in terms of the impact of temperature difference between rock and a flowing fracturing fluid. Micro-mechanical investigation of temperature and fracturing fluid effects on hydraulic fracturing damage in rocks is presented. It was found that fracture is shorter with pronounced secondary microcracking along the main fracture for the case when the convective–conductive thermal heat exchange is considered. First, the convection heat exchange during low-viscosity fluid infiltration in permeable rock around the wellbore causes significant rock cooling, where a finger-like fluid infiltration was observed. Second, fluid infiltration inhibits pressure rise during pumping and delays fracture initiation and propagation. Additionally, thermal damage occurs in the whole area around the wellbore due to rock cooling and cold fluid infiltration. The size of a damaged area around the wellbore increases with decreasing fluid dynamic viscosity. Fluid and rock compressibility ratio was found to have significant effect on the fracture propagation velocity.

  18. Modeling coupled thermal-mechanical processes of frozen soil induced by borehole heat exchanger

    Science.gov (United States)

    Shao, H.

    2015-12-01

    To utilize the shallow geothermal energy, heat pumps are often coupled with Borehole Heat Exchangers (BHE) to provide heating and cooling for buildings. In cold regions, soil freezing around the BHE is a potential problem which will dramatically influence the underground soil temperature distribution, subsequently the inlet and outlet refrigerant temperature of the BHE, and finally the efficiency of the heat pump. In this study, a numerical model has been developed to simulate the coupled temperature evolution both inside the BHE, and the propagating freezing front in the surrounding soil. The coupled model was validated against analytical solutions and experimental data. The influence of the freezing process on the overall system performance is investigated by comparing one long BHE configuration without freezing and another short one with latent heat from the frozen groundwater. It is found that when freezing happens, the coefficient of performance (COP) of the heat pump will decrease by around 0.5, leading to more electricity consumption. Furthermore, analysis of the simulation result reveals that the exploitation of latent heat through groundwater freezing is only economically attractive if electricity price is low and interest rate high, and it is not the case is most European countries.

  19. Compassionate love as a mechanism linking sacred qualities of marriage to older couples' marital satisfaction.

    Science.gov (United States)

    Sabey, Allen K; Rauer, Amy J; Jensen, Jakob F

    2014-10-01

    Previous work has underscored the robust links between sanctification of marriage and marital outcomes, and recent developments in the literature suggest that compassionate love, which is important for intimate relationships, may act as a mediator of that relationship. Accordingly, the current study used actor-partner interdependence models to examine the relationship between a spiritual cognition (i.e., perceived sacred qualities of marriage) and marital satisfaction, and to determine whether that relationship is mediated by compassionate love, in a sample of older married couples (N = 64). Results revealed that wives' greater sacred qualities of marriage were significantly and positively linked to marital satisfaction on the part of both spouses, and that these links were partially mediated by couples' reports of compassionate love. These findings highlight the importance of moving beyond simply establishing the existence of the link between global markers of involvement of religion and marriage to understanding how specific spiritual cognitions may foster better relationship quality, especially among older couples. (PsycINFO Database Record (c) 2014 APA, all rights reserved).

  20. Dual origins of measured phase-amplitude coupling reveal distinct neural mechanisms underlying episodic memory in the human cortex.

    Science.gov (United States)

    Vaz, Alex P; Yaffe, Robert B; Wittig, John H; Inati, Sara K; Zaghloul, Kareem A

    2017-03-01

    Phase-amplitude coupling (PAC) is hypothesized to coordinate neural activity, but its role in successful memory formation in the human cortex is unknown. Measures of PAC are difficult to interpret, however. Both increases and decreases in PAC have been linked to memory encoding, and PAC may arise due to different neural mechanisms. Here, we use a waveform analysis to examine PAC in the human cortex as participants with intracranial electrodes performed a paired associates memory task. We found that successful memory formation exhibited significant decreases in left temporal lobe and prefrontal cortical PAC, and these two regions exhibited changes in PAC within different frequency bands. Two underlying neural mechanisms, nested oscillations and sharp waveforms, were responsible for the changes in these regions. Our data therefore suggest that decreases in measured cortical PAC during episodic memory reflect two distinct underlying mechanisms that are anatomically segregated in the human brain. Published by Elsevier Inc.

  1. An electro-mechanically coupled model for the dynamic behavior of a dielectric electro-active polymer actuator

    Science.gov (United States)

    Hodgins, M.; Rizzello, G.; Naso, D.; York, A.; Seelecke, S.

    2014-10-01

    Dielectric electro-active polymer (DEAP) technology holds promise for enabling lightweight, energy efficient, and scalable actuators. The circular DEAP actuator configuration (also known as cone or diaphragm actuator) in particular shows potential in applications such as pumps, valves, micro-positioners and loudspeakers. For a quantitative prediction of the actuator behavior as well as for design optimization tasks, material models which can reproduce the coupled electromechanical behavior inherent to these actuators are necessary. This paper presents a non-linear viscoelastic model based on an electro-mechanical Ogden free energy expression for the DEAP. The DEAP model is coupled with a spring/mass system to study the dynamic performance of such a representative system from static behavior to 50 Hz. The system is identified and validated by several different experiments.

  2. Collider constraints on tuning in composite Higgs models

    Energy Technology Data Exchange (ETDEWEB)

    Barnard, James [ARC Centre of Excellence for Particle Physics at the Terascale, School of Physics,University of Melbourne, Victoria, 3010 (Australia); White, Martin [ARC Centre of Excellence for Particle Physics at the Terascale, School of Physics,University of Adelaide, South Australia, 5005 (Australia)

    2015-10-12

    Two potential sources of tuning exist in composite Higgs models: one comes from keeping the Higgs VEV below the compositeness scale and one comes from keeping the Higgs light after constraints on the top partner masses are applied. We construct a measure that determines whether these tunings are independent or not and combines them appropriately. We perform a comprehensive scan of the parameter space for three explicit models and report the minimum tuning values compatible with existing collider constraints. Tuning values are given as functions of resonance masses and deviations to the Higgs couplings so the effect of future constraints can easily be quantified. The current minimum tuning in the minimal model is 2.5–5% and will be decreased to around 0.8–3.3% if no top partners are observed over the lifetime of the LHC.

  3. Sustained anxiety increases amygdala–dorsomedial prefrontal coupling: a mechanism for maintaining an anxious state in healthy adults

    Science.gov (United States)

    Vytal, Katherine E.; Overstreet, Cassie; Charney, Danielle R.; Robinson, Oliver J.; Grillon, Christian

    2014-01-01

    Background Neuroimaging research has traditionally explored fear and anxiety in response to discrete threat cues (e.g., during fear conditioning). However, anxiety is a sustained aversive state that can persist in the absence of discrete threats. Little is known about mechanisms that maintain anxiety states over a prolonged period. Here, we used a robust translational paradigm (threat of shock) to induce sustained anxiety. Recent translational work has implicated an amygdala–prefrontal cortex (PFC) circuit in the maintenance of anxiety in rodents. To explore the functional homologues of this circuitry in humans, we used a novel paradigm to examine the impact of sustained anticipatory anxiety on amygdala–PFC intrinsic connectivity. Methods Task-independent fMRI data were collected in healthy participants during long-duration periods of shock anticipation and safety. We examined intrinsic functional connectivity. Results Our study involved 20 healthy participants. During sustained anxiety, amygdala activity was positively coupled with dorsomedial PFC (DMPFC) activity. High trait anxiety was associated with increased amygdala–DMPFC coupling. In addition, induced anxiety was associated with positive coupling between regions involved in defensive responding, and decreased coupling between regions involved in emotional control and the default mode network. Limitations Inferences regarding anxious pathology should be made with caution because this study was conducted in healthy participants. Conclusion Findings suggest that anticipatory anxiety increases intrinsic amygdala–DMPFC coupling and that the DMPFC may serve as a functional homologue for the rodent prefrontal regions by sustaining anxiety. Future research may use this defensive neural context to identify bio-markers of risk for anxious pathology and target these circuits for therapeutic intervention. PMID:24886788

  4. Multiscale Mechanics of Articular Cartilage: Potentials and Challenges of Coupling Musculoskeletal, Joint, and Microscale Computational Models

    Science.gov (United States)

    Halloran, J. P.; Sibole, S.; van Donkelaar, C. C.; van Turnhout, M. C.; Oomens, C. W. J.; Weiss, J. A.; Guilak, F.; Erdemir, A.

    2012-01-01

    Articular cartilage experiences significant mechanical loads during daily activities. Healthy cartilage provides the capacity for load bearing and regulates the mechanobiological processes for tissue development, maintenance, and repair. Experimental studies at multiple scales have provided a fundamental understanding of macroscopic mechanical function, evaluation of the micromechanical environment of chondrocytes, and the foundations for mechanobiological response. In addition, computational models of cartilage have offered a concise description of experimental data at many spatial levels under healthy and diseased conditions, and have served to generate hypotheses for the mechanical and biological function. Further, modeling and simulation provides a platform for predictive risk assessment, management of dysfunction, as well as a means to relate multiple spatial scales. Simulation-based investigation of cartilage comes with many challenges including both the computational burden and often insufficient availability of data for model development and validation. This review outlines recent modeling and simulation approaches to understand cartilage function from a mechanical systems perspective, and illustrates pathways to associate mechanics with biological function. Computational representations at single scales are provided from the body down to the microstructure, along with attempts to explore multiscale mechanisms of load sharing that dictate the mechanical environment of the cartilage and chondrocytes. PMID:22648577

  5. On phase transformation models for thermo-mechanically coupled response of Nitinol

    KAUST Repository

    Sengupta, Arkaprabha

    2011-03-31

    Fully coupled thermomechanical models for Nitinol at the grain level are developed in this work to capture the inter-dependence between deformation and temperature under non-isothermal conditions. The martensite transformation equations are solved using a novel algorithm which imposes all relevant constraints on the volume fractions. The numerical implementation of the resulting models within the finite element method is effected by the monolithic solution of the momentum and energy equations. Validation of the models is achieved by means of thin-tube experiments at different strain rates. © 2011 Springer-Verlag.

  6. Mechanisms of G Protein-Coupled Estrogen Receptor-Mediated Spinal Nociception

    DEFF Research Database (Denmark)

    Deliu, Elena; Brailoiu, G. Cristina; Arterburn, Jeffrey B.

    2012-01-01

    Human and animal studies suggest that estrogens are involved in the processing of nociceptive sensory information and analgesic responses in the central nervous system. Rapid pronociceptive estrogenic effects have been reported, some of which likely involve G protein-coupled estrogen receptor (GPER...... increase, ROS accumulation, and neuronal membrane depolarization. PerspectiveOur results suggest that GPER modulates pain processing in spinal sensory neurons via cytosolic calcium increase and ROS accumulation. These findings extend the current knowledge on GPER involvement in physiology and disease...

  7. Research on Heat-Mechanical Coupling of Ventilated Disc Brakes under the Condition of Emergency Braking

    Science.gov (United States)

    Tan, Xuelong; Zhang, Jian; Tang, Wenxian; Zhang, Yang

    Taking the ventilated disc brake in some company as research object, and using UG to build 3D models of brake disc and pad, and making use of ABAQUS/Standard to set up two parts' finite element model, via the decelerated motion of actual simulation brake disc, which gets ventilated disc brake in the case of emergency breaking in time and space distribution of conditions of temperature and stress field, summarizes the distribution of temperature field and stress field, proves complex coupling between temperature, stress, and supplies the direct basis for brake's fatigue life analysis.

  8. Coping with infertility: Comparison of coping mechanisms and psychological immune competence in fertile and infertile couples.

    Science.gov (United States)

    Nagy, Erika; Nagy, Beáta Erika

    2016-08-01

    This study compared coping strategies and psychological immunity of parents with a child conceived with assisted reproductive technology (n = 84) and parents with a naturally conceived child (n = 84) in a Hungarian fertility-age population. Results showed that in vitro fertilization parents are able to control their emotions in a better way than comparison couples. They interpret trials as challenges and consider themselves more worthy than the members of the control group. Our research confirms that consideration and management of psychological factors in treating infertility have an important preventive role to play. © The Author(s) 2015.

  9. Adaptive Self Tuning

    Energy Technology Data Exchange (ETDEWEB)

    2017-05-02

    The AST software includes numeric methods to 1) adjust STA/LTA signal detector trigger level (TL) values and 2) filter detections for a network of sensors. AST adapts TL values to the current state of the environment by leveraging cooperation within a neighborhood of sensors. The key metric that guides the dynamic tuning is consistency of each sensor with its nearest neighbors: TL values are automatically adjusted on a per station basis to be more or less sensitive to produce consistent agreement of detections in its neighborhood. The AST algorithm adapts in near real-time to changing conditions in an attempt to automatically self-tune a signal detector to identify (detect) only signals from events of interest.

  10. Changes in elbow joint's musculo-articular mechanical properties do not alter reaching-related action-perception coupling.

    Science.gov (United States)

    Daviaux, Yannick; Deschamps, Thibault; Cornu, Christophe

    2017-04-01

    Perception of action capabilities can be altered by changes in sensorimotor processes, as showed in previous works in populations dealing with regular and pathological sensorimotor deficits. Misestimating changes in performance ability could lead to risky behavior, injury, and/or reduced performance. However, the relationship between sensorimotor processes, the action-perception coupling, and the related anatomical structures is still a matter of debate. We investigated whether changes in the muscle-tendon system's mechanical properties experimentally induced by eccentric contractions could alter the action-perception coupling (APC) in a reaching-to-grasp task, in which the participants estimated the maximal distance they predicted that they would able to reach a glass. Based on their repartition, volunteers performed a conditioning session the first day: a series of isokinetic elbow extension in passive condition (control group, n = 11) or when performing elbow flexors eccentric contractions (eccentric group, n = 11). Performance estimates and actual performances in a reaching-to-grasp task were completed before, and immediately, 24 hours and 48 hours after the conditioning session. Alterations of musculo-articular mechanical properties were assessed through global joint stiffness (joint passive torque through load/unload cycles) and local stiffness (muscle elastography). The results showed that the APC related to reaching-to-grasp performance was not impacted by post-exercise changes in mechanical properties of the musculo-articular system. These findings emphasize the central dimension of sensorimotor processing instead of peripheral structures to investigate the APC for an altered sensorimotor environment.

  11. A versatile lab-on-chip test platform to characterize elementary deformation mechanisms and electromechanical couplings in nanoscopic objects

    Science.gov (United States)

    Pardoen, Thomas; Colla, Marie-Sthéphane; Idrissi, Hosni; Amin-Ahmadi, Behnam; Wang, Binjie; Schryvers, Dominique; Bhaskar, Umesh K.; Raskin, Jean-Pierre

    2016-03-01

    A nanomechanical on-chip test platform has recently been developed to deform under a variety of loading conditions freestanding thin films, ribbons and nanowires involving submicron dimensions. The lab-on-chip involves thousands of elementary test structures from which the elastic modulus, strength, strain hardening, fracture, creep properties can be extracted. The technique is amenable to in situ transmission electron microscopy (TEM) investigations to unravel the fundamental underlying deformation and fracture mechanisms that often lead to size-dependent effects in small-scale samples. The method allows addressing electrical and magnetic couplings as well in order to evaluate the impact of large mechanical stress levels on different solid-state physics phenomena. We had the chance to present this technique in details to Jacques Friedel in 2012 who, unsurprisingly, made a series of critical and very relevant suggestions. In the spirit of his legacy, the paper will address both mechanics of materials related phenomena and couplings with solids state physics issues.

  12. Tuning History: The French Experience

    Science.gov (United States)

    Lamboley, Jean-Luc

    2017-01-01

    The paper shows that Tuning Project has generated indifference more than resistance within the French academic community. It proposes an analysis of the reasons of this situation: difficulties arising from Tuning itself, the resistance of the French academic tradition, the institutional inhibitors and facilitators. The impact of Tuning on French…

  13. Direct observation of breaking of the intramolecular H-bond, and slowing down of the proton motion and tuning its mechanism in an HBO derivative.

    Science.gov (United States)

    Alarcos, Noemí; Gutiérrez, Mario; Liras, Marta; Sánchez, Félix; Moreno, Miquel; Douhal, Abderrazzak

    2015-06-14

    We report on spectroscopic and photodynamical behaviours of 5-amino-2-(2'-hydroxyphenyl)benzoxazole (5A-HBO) in different solutions. The dye undergoes an ultrafast ICT reaction (hydrogen bond (IHB). 5A-HBO in n-heptane solution exhibits an irreversible and slow (20 ps) ESIPT reaction, while that of the parent compound, HBO, takes place in less than 150 fs. Compared to excited HBO behaviour, theoretical calculations on 5A-HBO suggest a higher energy barrier (∼4 kcal mol(-1)) between the relaxed enol and keto tautomers, in addition to a less stabilization of the latter, which is in agreement with experiments in n-heptane. On the other hand, in dichloromethane, after the ICT reaction a subsequent and reversible proton motion occurs in an extraordinary slower regime (ns-time scale). No isotopic effect (OH/OD exchange) was observed in this solvent reflecting that the reversible ESIPT reaction evolves along the IHB and solvent coordinates. Using tetrahydrofurane and acetonitrile, we observed a breaking of the IHB due to specific intermolecular interactions with solvent molecules. This leads to the formation of open-enol forms, which undergo an ICT reaction as it occurs in 5A-MBO. These results bring new findings in the coupled ICT and ESIPT reactions. The photobehaviour of this new dye remarkably changes with the solvent nature, opening up the window for further research and possible applications in sensing polarity or H-bonding of media similar to that of the biological ones.

  14. Disentangling the mechanisms of the coupling between sea ice and tundra productivity: cold air advection vs. arctic amplification.

    Science.gov (United States)

    Macias-Fauria, M.; Karlsen, S. R.; Forbes, B. C.

    2016-12-01

    Changes in arctic terrestrial productivity have been associated with the decline in sea ice extent, concentration, and volume observed at a pan-Arctic scale during the last decades, on the basis that most tundra ecosystems lay close to the sea. However the mechanisms for this coupling remain elusive, and despite overall trend agreements between different components of the Arctic system, no clear hypothesis has successfully explained the heterogeneous spatial and temporal patterns of sea ice and tundra productivity. Here we propose two mechanisms through which sea ice might influence tundra productivity: (1) by advecting cold air from sea ice to the adjacent land during the growing season (cold air advection, local-to-regional control); (2) via changes in the regional climate linked to the snow-ice albedo feedbacks (arctic amplification, regional-to-pan-Arctic controls). We used 8-day Normalised Difference Vegetation Index (NDVI MODIS) and concurrent sea ice concentration data (Norwegian Sea Ice Service) to test the relative influence of cold air advection vs. arctic amplification over the Svalbard Archipelago (period 2000-2014). Singular Value Decomposition (SVD) analyses suggest that cold air advection affects tundra productivity in regions/periods where/when sea ice is close to the adjacent land during the growing season, whereas a more regional signal appears when sea ice is distant ( >100km) from the coast. Further analyses were performed using the same approach over the pan-Arctic region using bi-weekly NDVI (GIMMS-NDVI3g) and sea ice extent (NASA/JAXA dataset; period 1981-2015). We interpret that cold air advection locally causes temperatures in the adjacent land to drop ("true coupling"), whereas in the arctic amplification scenario both NDVI and regional sea ice concentration are collinearly related to warmer, regional-to-pan-Arctic temperatures. Our results offer a mechanism that successfully explains NDVI/sea ice coupling and its heterogeneous spatial and

  15. Magnetoelectric tuning of the inverse spin-Hall effect

    Science.gov (United States)

    Vargas, José M.; Gómez, Javier E.; Avilés-Félix, Luis; Butera, Alejandro

    2017-05-01

    We demonstrate in this article that the magnetoelectric (ME) mechanism can be exploited to control the spin current emitted in a spin pumping experiment using moderate electric fields. Spin currents were generated at the interface of a ferromagnet/metal bilayer by driving the system to the ferromagnetic resonance condition at X-Band (9.78 GHz) with an incident power of 200 mW. The ME structure, a thin (20 nm) FePt film grown on top of a polished 011-cut single crystal lead magnesium niobate-lead titanate (PMN-PT) slab, was prepared by dc magnetron sputtering. The PMN-PT/FePt was operated in the L-T mode (longitudinal magnetized-transverse polarized). This hybrid composite showed a large ME coefficient of 140 Oe cm/kV, allowing to easily tune the ferromagnetic resonance condition with electric field strengths below 4 kV/cm. A thin layer of Pt (10 nm) was grown on top of the PMN-PT/FePt structure and was used to generate and detect the spin current by taking advantage of its large spin-orbit coupling that produces a measurable signal via the inverse spin-Hall effect. These results proved an alternative way to tune the magnetic field at which the spin current is established and consequently the inverse spin-Hall effect signal, which can promote advances in hybrid spintronic devices.

  16. A Coupled Thermal–Hydrological–Mechanical Damage Model and Its Numerical Simulations of Damage Evolution in APSE

    Directory of Open Access Journals (Sweden)

    Chenhui Wei

    2016-10-01

    Full Text Available This paper proposes a coupled thermal–hydrological–mechanical damage (THMD model for the failure process of rock, in which coupling effects such as thermally induced rock deformation, water flow-induced thermal convection, and rock deformation-induced water flow are considered. The damage is considered to be the key factor that controls the THM coupling process and the heterogeneity of rock is characterized by the Weibull distribution. Next, numerical simulations on excavation-induced damage zones in Äspö pillar stability experiments (APSE are carried out and the impact of in situ stress conditions on damage zone distribution is analysed. Then, further numerical simulations of damage evolution at the heating stage in APSE are carried out. The impacts of in situ stress state, swelling pressure and water pressure on damage evolution at the heating stage are simulated and analysed, respectively. The simulation results indicate that (1 the v-shaped notch at the sidewall of the pillar is predominantly controlled by the in situ stress trends and magnitude; (2 at the heating stage, the existence of confining pressure can suppress the occurrence of damage, including shear damage and tensile damage; and (3 the presence of water flow and water pressure can promote the occurrence of damage, especially shear damage.

  17. Interior and exterior ballistics coupled optimization with constraints of attitude control and mechanical-thermal conditions

    Science.gov (United States)

    Liang, Xin-xin; Zhang, Nai-min; Zhang, Yan

    2016-07-01

    For solid launch vehicle performance promotion, a modeling method of interior and exterior ballistics associated optimization with constraints of attitude control and mechanical-thermal condition is proposed. Firstly, the interior and external ballistic models of the solid launch vehicle are established, and the attitude control model of the high wind area and the stage of the separation is presented, and the load calculation model of the drag reduction device is presented, and thermal condition calculation model of flight is presented. Secondly, the optimization model is established to optimize the range, which has internal and external ballistic design parameters as variables selected by sensitivity analysis, and has attitude control and mechanical-thermal conditions as constraints. Finally, the method is applied to the optimal design of a three stage solid launch vehicle simulation with differential evolution algorithm. Simulation results are shown that range capability is improved by 10.8%, and both attitude control and mechanical-thermal conditions are satisfied.

  18. Simulation of coupled flow and mechanical deformation using IMplicit Pressure-Displacement Explicit Saturation (IMPDES) scheme

    KAUST Repository

    El-Amin, Mohamed

    2012-01-01

    The problem of coupled structural deformation with two-phase flow in porous media is solved numerically using cellcentered finite difference (CCFD) method. In order to solve the system of governed partial differential equations, the implicit pressure explicit saturation (IMPES) scheme that governs flow equations is combined with the the implicit displacement scheme. The combined scheme may be called IMplicit Pressure-Displacement Explicit Saturation (IMPDES). The pressure distribution for each cell along the entire domain is given by the implicit difference equation. Also, the deformation equations are discretized implicitly. Using the obtained pressure, velocity is evaluated explicitly, while, using the upwind scheme, the saturation is obtained explicitly. Moreover, the stability analysis of the present scheme has been introduced and the stability condition is determined.

  19. Molecular Mechanisms for the Coupling of Endocytosis to Exocytosis in Neurons

    Science.gov (United States)

    Xie, Zhenli; Long, Jiangang; Liu, Jiankang; Chai, Zuying; Kang, Xinjiang; Wang, Changhe

    2017-01-01

    Neuronal communication and brain function mainly depend on the fundamental biological events of neurotransmission, including the exocytosis of presynaptic vesicles (SVs) for neurotransmitter release and the subsequent endocytosis for SV retrieval. Neurotransmitters are released through the Ca2+- and SNARE-dependent fusion of SVs with the presynaptic plasma membrane. Following exocytosis, endocytosis occurs immediately to retrieve SV membrane and fusion machinery for local recycling and thus maintain the homeostasis of synaptic structure and sustained neurotransmission. Apart from the general endocytic machinery, recent studies have also revealed the involvement of SNARE proteins (synaptobrevin, SNAP25 and syntaxin), synaptophysin, Ca2+/calmodulin, and members of the synaptotagmin protein family (Syt1, Syt4, Syt7 and Syt11) in the balance and tight coupling of exo-endocytosis in neurons. Here, we provide an overview of recent progress in understanding how these neuron-specific adaptors coordinate to ensure precise and efficient endocytosis during neurotransmission. PMID:28348516

  20. Coupling mechanism between geoacoustic emission and electromagnetic anomalies prior to earthquakes

    Directory of Open Access Journals (Sweden)

    Viacheslav Pilipenko

    2014-11-01

    Full Text Available Micro-cracking in the earthquake preparation zone is accompanied by the generation of acoustic emission (AE. Even low-intensity AE can essentially modify the underground fluid dynamics owing to the influence of high-frequency acoustic field on filtration process. Laboratory experiments show that acoustic impact on pour sample destroys a film with bounded water and results in a steep increase of its permeability up to 2 orders of magnitude. Impulsive acoustic fields also decrease the effective viscosity of the fluid. The occurrence in the crust under pressure of a region with distinct hydrodynamic and electrokinetic parameters will result in an appearance of anomalous telluric and magnetic fields on the surface above. This effect is estimated analytically using a simple model with an ellipticshaped inhomogeneity. The suggested hypothesis about possible coupling between AE and geoelectrical anomalies needs observational verification.

  1. DECOVALEX III PROJECT. Mathematical Models of Coupled Thermal-Hydro-Mechanical Processes for Nuclear Waste Repositories. Executive Summary

    Energy Technology Data Exchange (ETDEWEB)

    Jing, L.; Stephansson, O. [Royal Inst. of Technology, Stockholm (Sweden). Engineering Geology; Tsang, C.F. [Lawrence Berkely National Laboratory, Berkeley, CA (United States). Earth Science Div.; Mayor, J.C. [ENRESA, Madrid (Spain); Kautzky, F. [Swedish Nuclear Power Inspectorate, Stockholm (Sweden)] (eds.)

    2005-02-15

    DECOVALEX is an international consortium of governmental agencies associated with the disposal of high-level nuclear waste in a number of countries. The consortium's mission is the DEvelopment of COupled models and their VALidation against EXperiments. Hence the acronym/name DECOVALEX. Currently, agencies from Canada, Finland, France, Germany, Japan, Spain, Switzerland, Sweden, United Kingdom, and the United States are in DECOVALEX. Emplacement of nuclear waste in a repository in geologic media causes a number of physical processes to be intensified in the surrounding rock mass due to the decay heat from the waste. The four main processes of concern are thermal, hydrological, mechanical and chemical. Interactions or coupling between these heat-driven processes must be taken into account in modeling the performance of the repository for such modeling to be meaningful and reliable. DECOVALEX III is organized around four tasks. The FEBEX (Full-scale Engineered Barriers EXperiment) in situ experiment being conducted at the Grimsel site in Switzerland is to be simulated and analyzed in Task 1. Task 2, centered around the Drift Scale Test (DST) at Yucca Mountain in Nevada, USA, has several sub-tasks (Task 2A, Task 2B, Task 2C and Task 2D) to investigate a number of the coupled processes in the DST. Task 3 studies three benchmark problems: a) the effects of thermal-hydrologic-mechanical (THM) coupling on the performance of the near-field of a nuclear waste repository (BMT1); b) the effect of upscaling THM processes on the results of performance assessment (BMT2); and c) the effect of glaciation on rock mass behavior (BMT3). Task 4 is on the direct application of THM coupled process modeling in the performance assessment of nuclear waste repositories in geologic media. This executive summary presents the motivation, structure, objectives, approaches, and the highlights of the main achievements and outstanding issues of the tasks studied in the DECOVALEX III project

  2. Modeling the Coupled Chemo-Thermo-Mechanical Behavior of Amorphous Polymer Networks.

    Energy Technology Data Exchange (ETDEWEB)

    Zimmerman, Jonathan A. [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Nguyen, Thao D. [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Xiao, Rui [Sandia National Lab. (SNL-CA), Livermore, CA (United States)

    2015-02-01

    Amorphous polymers exhibit a rich landscape of time-dependent behavior including viscoelasticity, structural relaxation, and viscoplasticity. These time-dependent mechanisms can be exploited to achieve shape-memory behavior, which allows the material to store a programmed deformed shape indefinitely and to recover entirely the undeformed shape in response to specific environmental stimulus. The shape-memory performance of amorphous polymers depends on the coordination of multiple physical mechanisms, and considerable opportunities exist to tailor the polymer structure and shape-memory programming procedure to achieve the desired performance. The goal of this project was to use a combination of theoretical, numerical and experimental methods to investigate the effect of shape memory programming, thermo-mechanical properties, and physical and environmental aging on the shape memory performance. Physical and environmental aging occurs during storage and through exposure to solvents, such as water, and can significantly alter the viscoelastic behavior and shape memory behavior of amorphous polymers. This project – executed primarily by Professor Thao Nguyen and Graduate Student Rui Xiao at Johns Hopkins University in support of a DOE/NNSA Presidential Early Career Award in Science and Engineering (PECASE) – developed a theoretical framework for chemothermo- mechanical behavior of amorphous polymers to model the effects of physical aging and solvent-induced environmental factors on their thermoviscoelastic behavior.

  3. Mechanical analyses of the waveguide flange coupling for the first confinement system of the ITER electron cyclotron upper launcher

    Energy Technology Data Exchange (ETDEWEB)

    Mas Sánchez, Avelino, E-mail: avelino.massanchez@epfl.ch [Ecole Polytechnique Fédérale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas (CRPP), CH-1015 Lausanne (Switzerland); Bertizzolo, Robert; Chavan, René [Ecole Polytechnique Fédérale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas (CRPP), CH-1015 Lausanne (Switzerland); Gagliardi, Mario [Fusion for Energy, Josep Pla 2, Barcelona 08019 (Spain); Goodman, Timothy; Landis, Jean-Daniel [Ecole Polytechnique Fédérale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas (CRPP), CH-1015 Lausanne (Switzerland); Saibene, Gabriella [Fusion for Energy, Josep Pla 2, Barcelona 08019 (Spain); Santos Silva, Phillip [Ecole Polytechnique Fédérale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas (CRPP), CH-1015 Lausanne (Switzerland); Vaccaro, Alessandro [Karlsruhe Institute of Technology, D-76021 Karlsruhe (Germany)

    2016-11-01

    Highlights: • A double-metallic-seal waveguide flange coupling, capable of withstanding the expected load specification, has been designed. • The numerical simulations have shown that bending is the dominant load configuration for the current coupling concept. • The numerical studies indicate that an excessive seal decompression will not occur due to the expected load configurations. • Experimental tests show a good agreement with the results obtained in the numerical analyses. - Abstract: The four electron cyclotron (EC) upper port antennas (or “upper launchers” —UL) will be used to drive current locally inside magnetic islands located at the q = 2 (or smaller) rational surfaces in order to stabilize neoclassical tearing modes (NTMs), as well as heat inside of ρ of about 0.4. Each antenna consists of eight beam lines that are designed for the transmission of 1.5 MW of mm-wave power at 170 GHz. The First Confinement System (FCS) is formed by the ex-vessel mm-wave waveguide components, for which SIC-1 classification requirements apply. The beam lines in the FCS comprise a Z shaped set of straight corrugated waveguides with a nominal diameter of 50 mm connected by miter bends. This system is subjected to imposed displacements coming mainly from the thermal expansion of the vacuum vessel, seismic events and/or plasma disruption events. In absence of suitable SIC-1 waveguide bellows, the FCS waveguides must provide the necessary mechanical functional compliance. This has required the development of a dedicated, flange type coupling system with double metallic seals, capable of resisting the generated external loads while maintaining vacuum tightness and alignment. This paper presents the results of the design, analysis and pre-qualification experimental work done on the waveguides and the integrated SIC-1 compliant coupling system.

  4. A geometrical multi-scale numerical method for coupled hygro-thermo-mechanical problems in photovoltaic laminates.

    Science.gov (United States)

    Lenarda, P; Paggi, M

    A comprehensive computational framework based on the finite element method for the simulation of coupled hygro-thermo-mechanical problems in photovoltaic laminates is herein proposed. While the thermo-mechanical problem takes place in the three-dimensional space of the laminate, moisture diffusion occurs in a two-dimensional domain represented by the polymeric layers and by the vertical channel cracks in the solar cells. Therefore, a geometrical multi-scale solution strategy is pursued by solving the partial differential equations governing heat transfer and thermo-elasticity in the three-dimensional space, and the partial differential equation for moisture diffusion in the two dimensional domains. By exploiting a staggered scheme, the thermo-mechanical problem is solved first via a fully implicit solution scheme in space and time, with a specific treatment of the polymeric layers as zero-thickness interfaces whose constitutive response is governed by a novel thermo-visco-elastic cohesive zone model based on fractional calculus. Temperature and relative displacements along the domains where moisture diffusion takes place are then projected to the finite element model of diffusion, coupled with the thermo-mechanical problem by the temperature and crack opening dependent diffusion coefficient. The application of the proposed method to photovoltaic modules pinpoints two important physical aspects: (i) moisture diffusion in humidity freeze tests with a temperature dependent diffusivity is a much slower process than in the case of a constant diffusion coefficient; (ii) channel cracks through Silicon solar cells significantly enhance moisture diffusion and electric degradation, as confirmed by experimental tests.

  5. Multidimensional treatment of stochastic solvent dynamics in photoinduced proton-coupled electron transfer processes: sequential, concerted, and complex branching mechanisms.

    Science.gov (United States)

    Soudackov, Alexander V; Hazra, Anirban; Hammes-Schiffer, Sharon

    2011-10-14

    A theoretical approach for the multidimensional treatment of photoinduced proton-coupled electron transfer (PCET) processes in solution is presented. This methodology is based on the multistate continuum theory with an arbitrary number of diabatic electronic states representing the relevant charge distributions in a general PCET system. The active electrons and transferring proton(s) are treated quantum mechanically, and the electron-proton vibronic free energy surfaces are represented as functions of multiple scalar solvent coordinates corresponding to the single electron and proton transfer reactions involved in the PCET process. A dynamical formulation of the dielectric continuum theory is used to derive a set of coupled generalized Langevin equations of motion describing the time evolution of these collective solvent coordinates. The parameters in the Langevin equations depend on the solvent properties, such as the dielectric constants, relaxation time, and molecular moment of inertia, as well as the solute properties. The dynamics of selected intramolecular nuclear coordinates, such as the proton donor-acceptor distance or a torsional angle within the PCET complex, may also be included in this formulation. A surface hopping method in conjunction with the Langevin equations of motion is used to simulate the nonadiabatic dynamics on the multidimensional electron-proton vibronic free energy surfaces following photoexcitation. This theoretical treatment enables the description of both sequential and concerted mechanisms, as well as more complex processes involving a combination of these mechanisms. The application of this methodology to a series of model systems corresponding to collinear and orthogonal PCET illustrates fundamental aspects of these different mechanisms and elucidates the significance of proton vibrational relaxation and nonequilibrium solvent dynamics. © 2011 American Institute of Physics

  6. Regional-scale geomechanical impact assessment of underground coal gasification by coupled 3D thermo-mechanical modeling

    Science.gov (United States)

    Otto, Christopher; Kempka, Thomas; Kapusta, Krzysztof; Stańczyk, Krzysztof

    2016-04-01

    Underground coal gasification (UCG) has the potential to increase the world-wide coal reserves by utilization of coal deposits not mineable by conventional methods. The UCG process involves combusting coal in situ to produce a high-calorific synthesis gas, which can be applied for electricity generation or chemical feedstock production. Apart from its high economic potentials, UCG may induce site-specific environmental impacts such as fault reactivation, induced seismicity and ground subsidence, potentially inducing groundwater pollution. Changes overburden hydraulic conductivity resulting from thermo-mechanical effects may introduce migration pathways for UCG contaminants. Due to the financial efforts associated with UCG field trials, numerical modeling has been an important methodology to study coupled processes considering UCG performance. Almost all previous UCG studies applied 1D or 2D models for that purpose, that do not allow to predict the performance of a commercial-scale UCG operation. Considering our previous findings, demonstrating that far-field models can be run at a higher computational efficiency by using temperature-independent thermo-mechanical parameters, representative coupled simulations based on complex 3D regional-scale models were employed in the present study. For that purpose, a coupled thermo-mechanical 3D model has been developed to investigate the environmental impacts of UCG based on a regional-scale of the Polish Wieczorek mine located in the Upper Silesian Coal Basin. The model size is 10 km × 10 km × 5 km with ten dipping lithological layers, a double fault and 25 UCG reactors. Six different numerical simulation scenarios were investigated, considering the transpressive stress regime present in that part of the Upper Silesian Coal Basin. Our simulation results demonstrate that the minimum distance between the UCG reactors is about the six-fold of the coal seam thickness to avoid hydraulic communication between the single UCG

  7. The Effects of Coupling Agents on the Mechanical and Thermal Properties of Eucalyptus Flour/HDPE Composite

    Directory of Open Access Journals (Sweden)

    Metanawin Siripan

    2015-01-01

    Full Text Available The aim of this research was to study the effects of the coupling agents, FusabondTM E-528 (polyethylene-grafted maleic anhydride; PE-g-MA, MA and Amino Silane (Si, on the thermal properties, and mechanical properties of Eucalyptus flour-HDPE composite. Variation of the Eucalyptus flour contents in the HDPE resulted in properties of the composite. With increasing in the contents of Eucalyptus flour in polymer matrix, the mechanical properties of the HDPE composite decreased in EU-MA series samples while they were gradually decreased in EU-Si series samples. SEM micrographs showed the fracture surface of the HDPE/Eucalyptus composite at different ratios of Eucalyptus flour. SEM micrograpgh exhibited the dispersion of EU flour in polymer matrix. The samples of both coupling agents showed an increase in interfacial adhesion, observed for the considerable decreased of gaps between the matrix and the dispersed phase. However, the EU-MA sample appeared to be more uniformly than the EU-Si sample.

  8. Capturing intracellular pH dynamics by coupling its molecular mechanisms within a fully tractable mathematical model.

    Directory of Open Access Journals (Sweden)

    Yann Bouret

    Full Text Available We describe the construction of a fully tractable mathematical model for intracellular pH. This work is based on coupling the kinetic equations depicting the molecular mechanisms for pumps, transporters and chemical reactions, which determine this parameter in eukaryotic cells. Thus, our system also calculates the membrane potential and the cytosolic ionic composition. Such a model required the development of a novel algebraic method that couples differential equations for slow relaxation processes to steady-state equations for fast chemical reactions. Compared to classical heuristic approaches based on fitted curves and ad hoc constants, this yields significant improvements. This model is mathematically self-consistent and allows for the first time to establish analytical solutions for steady-state pH and a reduced differential equation for pH regulation. Because of its modular structure, it can integrate any additional mechanism that will directly or indirectly affect pH. In addition, it provides mathematical clarifications for widely observed biological phenomena such as overshooting in regulatory loops. Finally, instead of including a limited set of experimental results to fit our model, we show examples of numerical calculations that are extremely consistent with the wide body of intracellular pH experimental measurements gathered by different groups in many different cellular systems.

  9. Capturing intracellular pH dynamics by coupling its molecular mechanisms within a fully tractable mathematical model.

    Science.gov (United States)

    Bouret, Yann; Argentina, Médéric; Counillon, Laurent

    2014-01-01

    We describe the construction of a fully tractable mathematical model for intracellular pH. This work is based on coupling the kinetic equations depicting the molecular mechanisms for pumps, transporters and chemical reactions, which determine this parameter in eukaryotic cells. Thus, our system also calculates the membrane potential and the cytosolic ionic composition. Such a model required the development of a novel algebraic method that couples differential equations for slow relaxation processes to steady-state equations for fast chemical reactions. Compared to classical heuristic approaches based on fitted curves and ad hoc constants, this yields significant improvements. This model is mathematically self-consistent and allows for the first time to establish analytical solutions for steady-state pH and a reduced differential equation for pH regulation. Because of its modular structure, it can integrate any additional mechanism that will directly or indirectly affect pH. In addition, it provides mathematical clarifications for widely observed biological phenomena such as overshooting in regulatory loops. Finally, instead of including a limited set of experimental results to fit our model, we show examples of numerical calculations that are extremely consistent with the wide body of intracellular pH experimental measurements gathered by different groups in many different cellular systems.

  10. Modeling and experimental investigation of thermal-mechanical-electric coupling dynamics in a standing wave ultrasonic motor

    Science.gov (United States)

    Li, Xiang; Yao, Zhiyuan; He, Yigang; Dai, Shichao

    2017-09-01

    Ultrasonic motor operation relies on high-frequency vibration of a piezoelectric vibrator and interface friction between the stator and rotor/slider, which can cause temperature rise of the motor under continuous operation, and can affect motor parameters and performance in turn. In this paper, an integral model is developed to study the thermal-mechanical-electric coupling dynamics in a typical standing wave ultrasonic motor. Stick-slip motion at the contact interface and the temperature dependence of material parameters of the stator are taken into account in this model. The elastic, piezoelectric and dielectric material coefficients of the piezoelectric ceramic, as a function of temperature, are determined experimentally using a resonance method. The critical parameters in the model are identified via measured results. The resulting model can be used to evaluate the variation in output characteristics of the motor caused by the thermal-mechanical-electric coupling effects. Furthermore, the dynamic temperature rise of the motor can be accurately predicted under different input parameters using the developed model, which will contribute to improving the reliable life of a motor for long-term running.

  11. A variational formulation of the coupled thermo-mechanical boundary-value problem for general dissipative solids

    Science.gov (United States)

    Yang, Q.; Stainier, L.; Ortiz, M.

    2006-02-01

    A variational formulation of the coupled thermo-mechanical boundary-value problem for general dissipative solids is presented. The coupled thermo-mechanical boundary-value problem under consideration consists of the equilibrium problem for a deformable, inelastic and dissipative solid with the heat conduction problem appended in addition. The variational formulation allows for general dissipative solids, including finite elastic and plastic deformations, non-Newtonian viscosity, rate sensitivity, arbitrary flow and hardening rules, as well as heat conduction. We show that a joint potential function exists such that both the conservation of energy and the balance of linear momentum equations follow as Euler-Lagrange equations. The identification of the joint potential requires a careful distinction between equilibrium and external temperatures, which are equal at equilibrium. The variational framework predicts the fraction of dissipated energy that is converted to heat. A comparison of this prediction and experimental data suggests that α-titanium and Al2024-T conform to the variational framework.

  12. Simultaneous gains tuning in boiler/turbine PID-based controller clusters using iterative feedback tuning methodology.

    Science.gov (United States)

    Zhang, Shu; Taft, Cyrus W; Bentsman, Joseph; Hussey, Aaron; Petrus, Bryan

    2012-09-01

    Tuning a complex multi-loop PID based control system requires considerable experience. In today's power industry the number of available qualified tuners is dwindling and there is a great need for better tuning tools to maintain and improve the performance of complex multivariable processes. Multi-loop PID tuning is the procedure for the online tuning of a cluster of PID controllers operating in a closed loop with a multivariable process. This paper presents the first application of the simultaneous tuning technique to the multi-input-multi-output (MIMO) PID based nonlinear controller in the power plant control context, with the closed-loop system consisting of a MIMO nonlinear boiler/turbine model and a nonlinear cluster of six PID-type controllers. Although simplified, the dynamics and cross-coupling of the process and the PID cluster are similar to those used in a real power plant. The particular technique selected, iterative feedback tuning (IFT), utilizes the linearized version of the PID cluster for signal conditioning, but the data collection and tuning is carried out on the full nonlinear closed-loop system. Based on the figure of merit for the control system performance, the IFT is shown to deliver performance favorably comparable to that attained through the empirical tuning carried out by an experienced control engineer. Copyright © 2012 ISA. Published by Elsevier Ltd. All rights reserved.

  13. Coupled model analysis of the structure and nano-mechanical properties of dragonfly wings.

    Science.gov (United States)

    Sun, J Y; Pan, C X; Tong, J; Zhang, J

    2010-03-01

    To establish the quantitative model of the dragonfly wing the reconfiguration and nanoindentation technique were used. The mechanical properties of wings were measured by nanoindentre. Generally, the costa undertake is mainly pressure, and its mechanical properties should be the largest. However, in the nanoindentation test, the largest value of the reduced modulus (E(r)) and hardness (H) mainly appear in the radius, except the value at 0.7L (L is the wing length). The E(r) and H of the forewing were larger than that of the hindwing, except the value at 0.7L. The reversing engineering (3-D scanner) and AutoCAD were cooperated to reconfigure the dragonfly wing. Then the material parameters and skeleton transforms to a finite element analysis. The quantitative models were discussed in static range.

  14. Mechanical coupling between transsynaptic N-cadherin adhesions and actin flow stabilizes dendritic spines

    OpenAIRE

    Chazeau, Ana?l; Garcia, Mikael; Cz?nd?r, Katalin; Perrais, David; Tessier, B?atrice; Giannone, Gr?gory; Thoumine, Olivier

    2015-01-01

    The morphology of neuronal dendritic spines is a critical indicator of synaptic function. It is regulated by several factors, including the intracellular actin/myosin cytoskeleton and transcellular N-cadherin adhesions. To examine the mechanical relationship between these molecular components, we performed quantitative live-imaging experiments in primary hippocampal neurons. We found that actin turnover and structural motility were lower in dendritic spines than in immature filopodia and incr...

  15. A coupled electro-thermo-mechanical discontinuous Galerkin method applied on composite materials

    OpenAIRE

    Homsi, Lina; Noels, Ludovic

    2016-01-01

    Carbon fiber reinforced polymer composites have become increasingly important due to their unique properties which are appreciated in many practical applications such as low weight, low cost, low density, high mechanical characteristics. Moreover the range of their electrical conductivity can be controlled by the amount of carbon fibers. Carbon fiber reinforced polymer composites consist of at least two components, a polymer matrix (generally dielectric) and electrically conductive fillers. T...

  16. G protein-coupled receptor 56 regulates mechanical overload-induced muscle hypertrophy.

    Science.gov (United States)

    White, James P; Wrann, Christiane D; Rao, Rajesh R; Nair, Sreekumaran K; Jedrychowski, Mark P; You, Jae-Sung; Martínez-Redondo, Vicente; Gygi, Steven P; Ruas, Jorge L; Hornberger, Troy A; Wu, Zhidan; Glass, David J; Piao, Xianhua; Spiegelman, Bruce M

    2014-11-04

    Peroxisome proliferator-activated receptor gamma coactivator 1-alpha 4 (PGC-1α4) is a protein isoform derived by alternative splicing of the PGC1α mRNA and has been shown to promote muscle hypertrophy. We show here that G protein-coupled receptor 56 (GPR56) is a transcriptional target of PGC-1α4 and is induced in humans by resistance exercise. Furthermore, the anabolic effects of PGC-1α4 in cultured murine muscle cells are dependent on GPR56 signaling, because knockdown of GPR56 attenuates PGC-1α4-induced muscle hypertrophy in vitro. Forced expression of GPR56 results in myotube hypertrophy through the expression of insulin-like growth factor 1, which is dependent on Gα12/13 signaling. A murine model of overload-induced muscle hypertrophy is associated with increased expression of both GPR56 and its ligand collagen type III, whereas genetic ablation of GPR56 expression attenuates overload-induced muscle hypertrophy and associated anabolic signaling. These data illustrate a signaling pathway through GPR56 which regulates muscle hypertrophy associated with resistance/loading-type exercise.

  17. Mechanism study of biopolymer hair as a coupled thermo-water responsive smart material

    Science.gov (United States)

    Xiao, Xueliang; Zhou, Hongtao; Qian, Kun

    2017-03-01

    Animal hairs existing broadly in nature are found to be effectively responsive to stimuli of heat and water in sequence for shape deformation and recovery, namely, coupled shape memory function (CSMF). In the paper, the ability of thermo-water sensitive CSMF was first time investigated for animal hairs, the structural and molecular networks for net-points and switches were therefrom identified. Experimentally, animal hair manifested a high ability of shape fixation in thermal processing and good shape recovery by water stimulus. Characterizations of two stimuli (heating and hydration) were performed systematically on hair’s deformation, recovery, viscoelasticity and chemical components (crystalline phase, key bonds inamorphous area). The variations of related chemical components in molecular networks were also explored. A hybrid structural network model was thereafter proposed to interpret the thermo-water sensitive CSMF of hair. This study of two-sequential-stimuli CSMF is original and inspired to explore more complex functions of other smart natural materials and expected to make much smarter synthetic polymers.

  18. Model of polar auxin transport coupled to mechanical forces retrieves robust morphogenesis along the Arabidopsis root

    Science.gov (United States)

    Romero-Arias, J. Roberto; Hernández-Hernández, Valeria; Benítez, Mariana; Alvarez-Buylla, Elena R.; Barrio, Rafael A.

    2017-03-01

    Stem cells are identical in many scales, they share the same molecular composition, DNA, genes, and genetic networks, yet they should acquire different properties to form a functional tissue. Therefore, they must interact and get some external information from their environment, either spatial (dynamical fields) or temporal (lineage). In this paper we test to what extent coupled chemical and physical fields can underlie the cell's positional information during development. We choose the root apical meristem of Arabidopsis thaliana to model the emergence of cellular patterns. We built a model to study the dynamics and interactions between the cell divisions, the local auxin concentration, and physical elastic fields. Our model recovers important aspects of the self-organized and resilient behavior of the observed cellular patterns in the Arabidopsis root, in particular, the reverse fountain pattern observed in the auxin transport, the PIN-FORMED (protein family of auxin transporters) polarization pattern and the accumulation of auxin near the region of maximum curvature in a bent root. Our model may be extended to predict altered cellular patterns that are expected under various applied auxin treatments or modified physical growth conditions.

  19. A battery model that fully couples mechanics and electrochemistry at both particle and electrode levels by incorporation of particle interaction

    Science.gov (United States)

    Wu, Bin; Lu, Wei

    2017-08-01

    This paper develops a multi-scale mechanical-electrochemical model which enables fully coupled mechanics and electrochemistry at both particle and electrode levels. At the particle level, solid diffusion is modeled using a generalized chemical potential to capture the effects of mechanical stress and phase transformation. At the electrode level, the stress arising from particle interaction is incorporated in a continuum model. This particle interaction stress is in addition to the traditional concept of intercalation stress inside isolated particles. The particle and continuum electrode levels are linked by the particle interaction stress as loads on the particle surface, and by consideration of stress on the electrochemical reaction rate on the particle surface. The effect of mechanical stress on electrochemical reaction results in a stress-dependent over-potential between particle and electrolyte. Stress gradient in an electrode leads to inhomogeneous intercalation/deintercalation currents for particles depending on their interaction stress with neighbors, resulting in stress gradient induced inhomogeneous state of charge. Conversely, non-uniform intercalation/deintercalation currents in an electrode lead to stress between particles. With this model we have an important finding: an electrochemically inactive region in an electrode causes stress built-up. This model provides a powerful tool to address various problems such as fracture in-between particles.

  20. Cargo-shell and cargo-cargo couplings govern the mechanics of artificially loaded virus-derived cages

    Science.gov (United States)

    Llauró, Aida; Luque, Daniel; Edwards, Ethan; Trus, Benes L.; Avera, John; Reguera, David; Douglas, Trevor; Pablo, Pedro J. De; Castón, José R.

    2016-04-01

    Nucleic acids are the natural cargo of viruses and key determinants that affect viral shell stability. In some cases the genome structurally reinforces the shell, whereas in others genome packaging causes internal pressure that can induce destabilization. Although it is possible to pack heterologous cargoes inside virus-derived shells, little is known about the physical determinants of these artificial nanocontainers' stability. Atomic force and three-dimensional cryo-electron microscopy provided mechanical and structural information about the physical mechanisms of viral cage stabilization beyond the mere presence/absence of cargos. We analyzed the effects of cargo-shell and cargo-cargo interactions on shell stability after encapsulating two types of proteinaceous payloads. While bound cargo to the inner capsid surface mechanically reinforced the capsid in a structural manner, unbound cargo diffusing freely within the shell cavity pressurized the cages up to ~30 atm due to steric effects. Strong cargo-cargo coupling reduces the resilience of these nanocompartments in ~20% when bound to the shell. Understanding the stability of artificially loaded nanocages will help to design more robust and durable molecular nanocontainers.Nucleic acids are the natural cargo of viruses and key determinants that affect viral shell stability. In some cases the genome structurally reinforces the shell, whereas in others genome packaging causes internal pressure that can induce destabilization. Although it is possible to pack heterologous cargoes inside virus-derived shells, little is known about the physical determinants of these artificial nanocontainers' stability. Atomic force and three-dimensional cryo-electron microscopy provided mechanical and structural information about the physical mechanisms of viral cage stabilization beyond the mere presence/absence of cargos. We analyzed the effects of cargo-shell and cargo-cargo interactions on shell stability after encapsulating two

  1. Bioinspired coupled helical coils for soft tissue engineering of tubular structures - Improved mechanical behavior of tubular collagen type I templates.

    Science.gov (United States)

    Janke, H P; Bohlin, J; Lomme, R M L M; Mihaila, S M; Hilborn, J; Feitz, W F J; Oosterwijk, E

    2017-09-01

    The design of constructs for tubular tissue engineering is challenging. Most biomaterials need to be reinforced with supporting structures such as knittings, meshes or electrospun material to comply with the mechanical demands of native tissues. In this study, coupled helical coils (CHCs) were manufactured to mimic collagen fiber orientation as found in nature. Monofilaments of different commercially available biodegradable polymers were wound and subsequently fused, resulting in right-handed and left-handed polymer helices fused together in joints where the filaments cross. CHCs of different polymer composition were tested to determine the tensile strength, strain recovery, hysteresis, compressive strength and degradation of CHCs of different composition. Subsequently, seamless and stable hybrid constructs consisting of PDSII® USP 2-0 CHCs embedded in porous collagen type I were produced. Compared to collagen alone, this hybrid showed superior strain recovery (93.5±0.9% vs 71.1±12.6% in longitudinal direction; 87.1±6.6% vs 57.2±4.6% in circumferential direction) and hysteresis (18.9±2.7% vs 51.1±12.0% in longitudinal direction; 11.5±4.6% vs 46.3±6.3% in circumferential direction). Furthermore, this hybrid construct showed an improved Young's modulus in both longitudinal (0.5±0.1MPavs 0.2±0.1MPa; 2.5-fold) and circumferential (1.65±0.07MPavs (2.9±0.3)×10-2MPa; 57-fold) direction, respectively, compared to templates created from collagen alone. Moreover, hybrid template characteristics could be modified by changing the CHC composition and CHCs were produced showing a mechanical behavior similar to the native ureter. CHC-enforced templates, which are easily tunable to meet different demands may be promising for tubular tissue engineering. Most tubular constructs lack sufficient strength and tunability to comply with the mechanical demands of native tissues. Therefore, we embedded coupled helical coils (CHCs) produced from biodegradable polymers - to

  2. Mechanical coupling between transsynaptic N-cadherin adhesions and actin flow stabilizes dendritic spines.

    Science.gov (United States)

    Chazeau, Anaël; Garcia, Mikael; Czöndör, Katalin; Perrais, David; Tessier, Béatrice; Giannone, Grégory; Thoumine, Olivier

    2015-03-01

    The morphology of neuronal dendritic spines is a critical indicator of synaptic function. It is regulated by several factors, including the intracellular actin/myosin cytoskeleton and transcellular N-cadherin adhesions. To examine the mechanical relationship between these molecular components, we performed quantitative live-imaging experiments in primary hippocampal neurons. We found that actin turnover and structural motility were lower in dendritic spines than in immature filopodia and increased upon expression of a nonadhesive N-cadherin mutant, resulting in an inverse relationship between spine motility and actin enrichment. Furthermore, the pharmacological stimulation of myosin II induced the rearward motion of actin structures in spines, showing that myosin II exerts tension on the actin network. Strikingly, the formation of stable, spine-like structures enriched in actin was induced at contacts between dendritic filopodia and N-cadherin-coated beads or micropatterns. Finally, computer simulations of actin dynamics mimicked various experimental conditions, pointing to the actin flow rate as an important parameter controlling actin enrichment in dendritic spines. Together these data demonstrate that a clutch-like mechanism between N-cadherin adhesions and the actin flow underlies the stabilization of dendritic filopodia into mature spines, a mechanism that may have important implications in synapse initiation, maturation, and plasticity in the developing brain. © 2015 Chazeau, Garcia, Czöndör, et al. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

  3. Seismicity induced by CO2 injection: lesson learned from coupled hydro-mechanical modeling

    Science.gov (United States)

    Rinaldi, Antonio Pio; Rutqvist, Jonny; Urpi, Luca; Cappa, Frederic; Jeanne, Pierre; Vilarrasa, Victor

    2017-04-01

    Overpressure caused by the direct injection of CO2 into a deep sedimentary system may produce changes in the state of stress, as well as, have an impact on the sealing capabilities of the targeted system. The importance of geomechanics including the potential for reactivating faults associated with large-scale geologic carbon sequestration operations has recently become more widely recognized. In this context, here we review and summarize some recent modeling efforts, aimed at understanding the possible seismicity induced by CO2 storage and its relation to potential leakage to shallow groundwater aquifer during active injection. The simulations were conducted using TOUGH-FLAC, a simulator for coupled multiphase flow and geomechanical modeling. We carried out both quasi-static and dynamic simulations, with an explicit representation of a fault. In the case of quasi-static modeling, a strain softening Mohr-Coulomb model was used to model a slip-weakening fault slip behavior, enabling modeling of sudden slip that was interpreted as a seismic event, with a moment magnitude evaluated using formulas from seismology. In the case of dynamic modeling, we simulate the fault behavior as strain-softening or rate-dependent, analyzing the frequency behavior at surface and the possible effects of friction properties on slip. This work aims at studying the fault responses during carbon dioxide injection, focusing on the short-term (5 years) integrity of the storage repository, and hence, on the potential leakage towards shallow groundwater aquifers. We account for stress/strain-dependent permeability and study both the fault reactivation and the leakage through the fault zone. We analyze several scenarios related to the injected amount of CO2 (and hence related to potential overpressure) involving both minor and major faults, and study induced seismicity and leakage for different stress/strain permeability coupling functions, as well as increasing the complexity of the system in

  4. Coupled transverse and torsional vibrations in a mechanical system with two identical beams

    Science.gov (United States)

    Vlase, S.; Marin, M.; Scutaru, M. L.; Munteanu, R.

    2017-06-01

    The paper aims to study a plane system with bars, with certain symmetries. Such problems can be encountered frequently in industry and civil engineering. Considerations related to the economy of the design process, constructive simplicity, cost and logistics make the use of identical parts a frequent procedure. The paper aims to determine the properties of the eigenvalues and eigenmodes for transverse and torsional vibrations of a mechanical system where two of the three component bars are identical. The determination of these properties allows the calculus effort and the computation time and thus increases the accuracy of the results in such matters.

  5. Mechanisms of molecular electronic rectification through electronic levels with strong vibrational coupling

    DEFF Research Database (Denmark)

    Kuznetsov, A.M.; Ulstrup, Jens

    2002-01-01

    , corresponding to the fully diabatic limit. The rectification process then reduces to a sequence of vibrationally relaxed single-electron transfer steps. In the limits where the interactions are strong, denoted as the partially and fully adiabatic limits, the character of the rectification process is different......, and electron flow proceeds coherently, without vibrational relaxation. In still another class of mechanisms the electronic level broadening of either donor or acceptor from the adjacent electrode is so strong that it is comparable to the vibrational broadening. The process then reduces to a three...

  6. Coupled transverse and torsional vibrations in a mechanical system with two identical beams

    Directory of Open Access Journals (Sweden)

    S. Vlase

    2017-06-01

    Full Text Available The paper aims to study a plane system with bars, with certain symmetries. Such problems can be encountered frequently in industry and civil engineering. Considerations related to the economy of the design process, constructive simplicity, cost and logistics make the use of identical parts a frequent procedure. The paper aims to determine the properties of the eigenvalues and eigenmodes for transverse and torsional vibrations of a mechanical system where two of the three component bars are identical. The determination of these properties allows the calculus effort and the computation time and thus increases the accuracy of the results in such matters.

  7. Action and perception are temporally coupled by a common mechanism that leads to a timing misperception.

    Science.gov (United States)

    Pretegiani, Elena; Astefanoaei, Corina; Daye, Pierre M; FitzGibbon, Edmond J; Creanga, Dorina-Emilia; Rufa, Alessandra; Optican, Lance M

    2015-01-28

    We move our eyes to explore the world, but visual areas determining where to look next (action) are different from those determining what we are seeing (perception). Whether, or how, action and perception are temporally coordinated is not known. The preparation time course of an action (e.g., a saccade) has been widely studied with the gap/overlap paradigm with temporal asynchronies (TA) between peripheral target onset and fixation point offset (gap, synchronous, or overlap). However, whether the subjects perceive the gap or overlap, and when they perceive it, has not been studied. We adapted the gap/overlap paradigm to study the temporal coupling of action and perception. Human subjects made saccades to targets with different TAs with respect to fixation point offset and reported whether they perceived the stimuli as separated by a gap or overlapped in time. Both saccadic and perceptual report reaction times changed in the same way as a function of TA. The TA dependencies of the time change for action and perception were very similar, suggesting a common neural substrate. Unexpectedly, in the perceptual task, subjects misperceived lights overlapping by less than ∼100 ms as separated in time (overlap seen as gap). We present an attention-perception model with a map of prominence in the superior colliculus that modulates the stimulus signal's effectiveness in the action and perception pathways. This common source of modulation determines how competition between stimuli is resolved, causes the TA dependence of action and perception to be the same, and causes the misperception. Copyright © 2015 the authors 0270-6474/15/351493-12$15.00/0.

  8. Action and Perception Are Temporally Coupled by a Common Mechanism That Leads to a Timing Misperception

    Science.gov (United States)

    Astefanoaei, Corina; Daye, Pierre M.; FitzGibbon, Edmond J.; Creanga, Dorina-Emilia; Rufa, Alessandra; Optican, Lance M.

    2015-01-01

    We move our eyes to explore the world, but visual areas determining where to look next (action) are different from those determining what we are seeing (perception). Whether, or how, action and perception are temporally coordinated is not known. The preparation time course of an action (e.g., a saccade) has been widely studied with the gap/overlap paradigm with temporal asynchronies (TA) between peripheral target onset and fixation point offset (gap, synchronous, or overlap). However, whether the subjects perceive the gap or overlap, and when they perceive it, has not been studied. We adapted the gap/overlap paradigm to study the temporal coupling of action and perception. Human subjects made saccades to targets with different TAs with respect to fixation point offset and reported whether they perceived the stimuli as separated by a gap or overlapped in time. Both saccadic and perceptual report reaction times changed in the same way as a function of TA. The TA dependencies of the time change for action and perception were very similar, suggesting a common neural substrate. Unexpectedly, in the perceptual task, subjects misperceived lights overlapping by less than ∼100 ms as separated in time (overlap seen as gap). We present an attention-perception model with a map of prominence in the superior colliculus that modulates the stimulus signal's effectiveness in the action and perception pathways. This common source of modulation determines how competition between stimuli is resolved, causes the TA dependence of action and perception to be the same, and causes the misperception. PMID:25632126

  9. A visoelastic constitutive model for magneto-mechanical coupling of magnetorheological elastomers

    Science.gov (United States)

    Kou, Yong; Jin, Ke; Xu, Liqin; Zheng, Xiaojing

    2017-11-01

    This paper focuses on the behavior of field-dependent viscoelasticity for magnetorheological elastomers (MREs). A novel nonlinear constitutive model for magneto-viscoelastic behavior of MREs is proposed. The model considered here is thermodynamically motivated and based on the second law. An extended three-parameter standard linear solid model is proposed to describe the viscoelastic behavior of MREs, where the effect of particles on the elastomers at zero field is taken into account. Furthermore, the nonlinear magnetization and the local magnetic field within the ferromagnetic particle are incorporated to describe field-dependent constitutive behavior based on the dipole model. Then a set of analytical expressions of the constitutive law for MREs are obtained, and the parameters appearing in the model can be determined by those measurable experiments in mechanics and physics. The quantitative results demonstrate that this model can well capture the constitutive relation under both quasi-static and dynamic shear loading.

  10. Ca2+-Dependent Regulations and Signaling in Skeletal Muscle: From Electro-Mechanical Coupling to Adaptation

    Directory of Open Access Journals (Sweden)

    Sebastian Gehlert

    2015-01-01

    Full Text Available Calcium (Ca2+ plays a pivotal role in almost all cellular processes and ensures the functionality of an organism. In skeletal muscle fibers, Ca2+ is critically involved in the innervation of skeletal muscle fibers that results in the exertion of an action potential along the muscle fiber membrane, the prerequisite for skeletal muscle contraction. Furthermore and among others, Ca2+ regulates also intracellular processes, such as myosin-actin cross bridging, protein synthesis, protein degradation and fiber type shifting by the control of Ca2+-sensitive proteases and transcription factors, as well as mitochondrial adaptations, plasticity and respiration. These data highlight the overwhelming significance of Ca2+ ions for the integrity of skeletal muscle tissue. In this review, we address the major functions of Ca2+ ions in adult muscle but also highlight recent findings of critical Ca2+-dependent mechanisms essential for skeletal muscle-regulation and maintenance.

  11. Adaptive coupling between damage mechanics and peridynamics: a route for objective simulation of material degradation up to complete failure

    KAUST Repository

    Han, Fei

    2016-05-17

    The objective (mesh-independent) simulation of evolving discontinuities, such as cracks, remains a challenge. Current techniques are highly complex or involve intractable computational costs, making simulations up to complete failure difficult. We propose a framework as a new route toward solving this problem that adaptively couples local-continuum damage mechanics with peridynamics to objectively simulate all the steps that lead to material failure: damage nucleation, crack formation and propagation. Local-continuum damage mechanics successfully describes the degradation related to dispersed microdefects before the formation of a macrocrack. However, when damage localizes, it suffers spurious mesh dependency, making the simulation of macrocracks challenging. On the other hand, the peridynamic theory is promising for the simulation of fractures, as it naturally allows discontinuities in the displacement field. Here, we present a hybrid local-continuum damage/peridynamic model. Local-continuum damage mechanics is used to describe “volume” damage before localization. Once localization is detected at a point, the remaining part of the energy is dissipated through an adaptive peridynamic model capable of the transition to a “surface” degradation, typically a crack. We believe that this framework, which actually mimics the real physical process of crack formation, is the first bridge between continuum damage theories and peridynamics. Two-dimensional numerical examples are used to illustrate that an objective simulation of material failure can be achieved by this method.

  12. $K$-essence model from the mechanical approach point of view: coupled scalar field and the late cosmic acceleration

    CERN Document Server

    Bouhmadi-López, Mariam; Marto, João; Morais, João; Zhuk, Alexander

    2016-01-01

    In this paper, we consider the Universe at the late stage of its evolution and deep inside the cell of uniformity. At these scales, we can consider the Universe to be filled with dust-like matter in the form of discretely distributed galaxies, a $K$-essence scalar field, playing the role of dark energy, and radiation as matter sources. We investigate such a Universe in the mechanical approach. This means that the peculiar velocities of the inhomogeneities (in the form of galaxies) as well as the fluctuations of the other perfect fluids are non-relativistic. Such fluids are designated as coupled because they are concentrated around the inhomogeneities. In the present paper, we investigate the conditions under which the $K$-essence scalar field with the most general form for its action can become coupled. We investigate at the background level three particular examples of the $K$-essence models: (i) the pure kinetic $K$-essence field, (ii) a $K$-essence with a constant speed of sound and (iii) the $K$-essence m...

  13. Mechanism of conformational coupling in SecA: Key role of hydrogen-bonding networks and water interactions.

    Science.gov (United States)

    Milenkovic, Stefan; Bondar, Ana-Nicoleta

    2016-02-01

    SecA uses the energy yielded by the binding and hydrolysis of adenosine triphosphate (ATP) to push secretory pre-proteins across the plasma membrane in bacteria. Hydrolysis of ATP occurs at the nucleotide-binding site, which contains the conserved carboxylate groups of the DEAD-box helicases. Although crystal structures provide valuable snapshots of SecA along its reaction cycle, the mechanism that ensures conformational coupling between the nucleotide-binding site and the other domains of SecA remains unclear. The observation that SecA contains numerous hydrogen-bonding groups raises important questions about the role of hydrogen-bonding networks and hydrogen-bond dynamics in long-distance conformational couplings. To address these questions, we explored the molecular dynamics of SecA from three different organisms, with and without bound nucleotide, in water. By computing two-dimensional hydrogen-bonding maps we identify networks of hydrogen bonds that connect the nucleotide-binding site to remote regions of the protein, and sites in the protein that respond to specific perturbations. We find that the nucleotide-binding site of ADP-bound SecA has a preferred geometry whereby the first two carboxylates of the DEAD motif bridge via hydrogen-bonding water. Simulations of a mutant with perturbed ATP hydrolysis highlight the water-bridged geometry as a key structural element of the reaction path. Copyright © 2015. Published by Elsevier B.V.

  14. Impact analysis of the thermal mechanical coupling characteristics of graphite morphologies during laser cladding of gray cast iron

    Science.gov (United States)

    Yi, Peng; Liu, Yancong; Fan, Changfeng; Zhan, Xianghua; Xu, Pengyun; Liu, Tuo

    2017-05-01

    Cladding and numerical experiments on thermodynamic coupling were conducted to determine the thermal response features and microcracks of graphite and environment phases during surface laser cladding of gray cast iron. A micromodel of graphite-environment phase was established using numerical methods. On the basis of this model, a quantitative analysis on the thermal mechanical coupling characteristics of microstructures was realized, the relationship with microcracks at tip of graphite was established, and the influence of morphological difference on local stress concentration was obtained. Results showed considerable stress concentration at the tip of graphite during cooling stage, and on the whole, the stress concentration at both ends of graphite was in direct proportion to the length of the graphite. Moreover, sufficiently short graphite resulted in further increase in stress concentration. The influence caused by tip angle was more considerable than that of length, and sharpness was in direct proportion to stress concentration. For stress fields at both ends of dimer graphite, collinear distribution easily caused stress concentration, and more obvious stress concentration was observed when the two tips were closer. The interactive effect was weak and the influence on stress concentration was minimal when two graphite pieces were in parallel or vertical distribution.

  15. Bonding Strength Effects in Hydro-Mechanical Coupling Transport in Granular Porous Media by Pore-Scale Modeling

    Directory of Open Access Journals (Sweden)

    Zhiqiang Chen

    2016-03-01

    Full Text Available The hydro-mechanical coupling transport process of sand production is numerically investigated with special attention paid to the bonding effect between sand grains. By coupling the lattice Boltzmann method (LBM and the discrete element method (DEM, we are able to capture particles movements and fluid flows simultaneously. In order to account for the bonding effects on sand production, a contact bond model is introduced into the LBM-DEM framework. Our simulations first examine the experimental observation of “initial sand production is evoked by localized failure” and then show that the bonding or cement plays an important role in sand production. Lower bonding strength will lead to more sand production than higher bonding strength. It is also found that the influence of flow rate on sand production depends on the bonding strength in cemented granular media, and for low bonding strength sample, the higher the flow rate is, the more severe the erosion found in localized failure zone becomes.

  16. Mechanically flexible waveguide arrays for optical chip-to-chip coupling

    Science.gov (United States)

    Peters, Tjitte-Jelte; Tichem, Marcel

    2016-03-01

    This paper reports on the progress related to a multichannel photonic alignment concept, which aims to achieve submicrometer alignment of the waveguides of two photonic integrated circuits (PICs). The concept consists of two steps: chip-to-chip positioning and fixing provide a coarse alignment after which waveguide-to-waveguide positioning and fixing result in a fine alignment. For the waveguide-to-waveguide alignment, mechanically flexible waveguides are used. Positioning of the waveguides is performed by integrated MEMS actuators. The flexible waveguides and the actuators are both integrated in one of the PICs. This paper reports on the fabrication and the mechanical characterization of the suspended waveguide structures. The flexible waveguide array is created in a PIC which is based on TriPleX technology, i.e. a silicon nitride (Si3N4) core encapsulated in a silicon dioxide (SiO2) cladding. The realized flexible waveguide structures consist of parallel cantilevered waveguide beams and a crossbar that connects the free ends of the waveguide beams. The fabrication of suspended structures consisting of a thick, i.e. 15 µm, TriPleX layer stack is challenged by the compressive mean stress in the SiO2. We have developed a fabrication method for the reliable release of flexible TriPleX structures, resulting in a 96% yield of cantilever beams. The realized suspended waveguide arrays have a natural out-of-plane deformation, which is studied using white light interferometry. Suspended waveguide beams reveal a downward slope at the base of the beams close to 0:5_. In addition to this slope, the beams have a concave upward profile. The constant curvature over the length of the waveguide beams is measured to range from 0:2 µm to 0:8 µm. The profiles measured over the length of the crossbars do not seem to follow a circular curvature. The variation in deflection within crossbars is measured to be smaller than 0:2 µm.

  17. Wind Induced Vibration Control and Energy Harvesting of Electromagnetic Resonant Shunt Tuned Mass-Damper-Inerter for Building Structures

    Directory of Open Access Journals (Sweden)

    Yifan Luo

    2017-01-01

    Full Text Available This paper proposes a novel inerter-based dynamic vibration absorber, namely, electromagnetic resonant shunt tuned mass-damper-inerter (ERS-TMDI. To obtain the performances of the ERS-TMDI, the combined ERS-TMDI and a single degree of freedom system are introduced. H2 criteria performances of the ERS-TMDI are introduced in comparison with the classical tuned mass-damper (TMD, the electromagnetic resonant shunt series TMDs (ERS-TMDs, and series-type double-mass TMDs with the aim to minimize structure damage and simultaneously harvest energy under random wind excitation. The closed form solutions, including the mechanical tuning ratio, the electrical damping ratio, the electrical tuning ratio, and the electromagnetic mechanical coupling coefficient, are obtained. It is shown that the ERS-TMDI is superior to the classical TMD, ERS-TMDs, and series-type double-mass TMDs systems for protection from structure damage. Meanwhile, in the time domain, a case study of Taipei 101 tower is presented to demonstrate the dual functions of vibration suppression and energy harvesting based on the simulation fluctuating wind series, which is generated by the inverse fast Fourier transform method. The effectiveness and robustness of ERS-TMDI in the frequency and time domain are illustrated.

  18. Coupled Electro-thermal-mechanical and Transient Characteristic for Micro Gas Pressure Sensor Micro-hotplate-based

    Directory of Open Access Journals (Sweden)

    Rencheng Jin

    2011-08-01

    Full Text Available The electrothermal theoretical analysis of micro-hotplate-based air pressure sensor is carried out and its model is built up, which is based on the classical heat transfer theory and rarefied gas dynamics. According to the heat transfer theory analysis of the micro hotplate (MHP and the thermal finite element simulation, coupled electro-thermal-mechanical model of micro-hotplate-based air pressure sensor is established. The finite element analysis software ANSYS helps to process thermal analysis for the micro hotplate, and the appropriate width of supporting bridge is chosen. The paper carried out a transient response analysis for the micro hotplate, which showed the changing process of the temperature and deformation of MHP in detail for further study. The research work provided a more feasible analysis method in the theoretical study of micro hotplate.

  19. Validation of a 3-D, Thermo-Mechanically Coupled Model for Multi-Pass Rolling in a Reversing Mill

    Science.gov (United States)

    Rhee, Moono; Wang, Paul; Li, Ming; Becker, Richard

    2004-06-01

    A three dimensional numerical model simulating multi-pass, hot rolling on a reversing mill has been developed to analyze deformation patterns and shape changes of a rolled ingot. Validation simulations through 15 passes with an 86% reduction have been performed using the thermo-mechanically coupled model to track the evolution of the deformed ingot geometry. The heat transfer coefficient for thermal conduction between the rolls and slab has been estimated in accordance with experimental data, and heat transfer to the air and coolant outside of the roll bite is included. A hyperbolic sine model using the Zener-Hollomon parameter is used to capture the temperature and strain rate dependence of the aluminum alloy. A Coulomb friction model with a flow strength dependent maximum limit on the interfacial shear stress was employed between the rolls and ingot. Results of validation simulations and comparisons with experiments focusing on the ingot shape evolution are discussed.

  20. Molecular Mechanism for Inhibition of G Protein-Coupled Receptor Kinase 2 by a Selective RNA Aptamer

    Energy Technology Data Exchange (ETDEWEB)

    Tesmer, Valerie M.; Lennarz, Sabine; Mayer, Günter; Tesmer, John J.G. (Bonn); (Michigan)

    2012-08-31

    Cardiovascular homeostasis is maintained in part by the rapid desensitization of activated heptahelical receptors that have been phosphorylated by G protein-coupled receptor kinase 2 (GRK2). However, during chronic heart failure GRK2 is upregulated and believed to contribute to disease progression. We have determined crystallographic structures of GRK2 bound to an RNA aptamer that potently and selectively inhibits kinase activity. Key to the mechanism of inhibition is the positioning of an adenine nucleotide into the ATP-binding pocket and interactions with the basic {alpha}F-{alpha}G loop region of the GRK2 kinase domain. Constraints imposed on the RNA by the terminal stem of the aptamer also play a role. These results highlight how a high-affinity aptamer can be used to selectively trap a novel conformational state of a protein kinase.

  1. The coupled thermo-mechanical-microstructural finite element modeling of hot stamping process in 22MnB5 steel

    Science.gov (United States)

    Chen, Xiangjun; Xiao, Namin; Li, Dianzhong; Li, Guangyao; Sun, Guangyong

    2013-12-01

    In this study, a coupled thermo-mechanical-microstructural finite element model based on the subroutine of commercial software ABAQUS is developed to predict the hot stamping process in 22MnB5 steel. The Johnson-Mehl-Avrami-Kolmogorov type model with Scheil' additivity rule and Koistinen-Marburger model are adopted to simulate the diffusional phase transformation and diffusionless one respectively. During the calculation of temperature and stress/strain field, the contributions of microstructure evolution, e.g. transformation latent heat, transformation strain, and transformation plasticity are taken into account, which give more insight of the material response. The model allows to evaluate the transient stress and strain distributions, the final microstructure constituent and the final distortion of the sheet part during the press quenching process. The effect of transformation plasticity on the geometry precision and the residual stress are discussed.

  2. The coupled and uncoupled mechanisms by which trans-acting factors regulate mRNA stability and translation.

    Science.gov (United States)

    Fukao, Akira; Fujiwara, Toshinobu

    2017-04-01

    In mammals, spatiotemporal control of protein synthesis plays a key role in the post-transcriptional regulation of gene expression during cell proliferation, development and differentiation and RNA-binding proteins (RBPs) and microRNAs (miRNAs) are required for this phenomenon. RBPs and miRNAs control the levels of mRNA protein products by regulating mRNA stability and translation. Recent studies have shown that RBPs and miRNAs simultaneously regulate mRNA stability and translation, and that the differential functions of RBPs and miRNAs are dependent on their interaction partners. Here, we summarize the coupled- and uncoupled mechanisms by which trans-acting factors regulate mRNA stability and translation. © The Authors 2016. Published by Oxford University Press on behalf of the Japanese Biochemical Society. All rights reserved.

  3. Effect of Coupling Agent on Mechanical Properties of Palm Petiole Nanofiber Reinforced Composite

    Science.gov (United States)

    Vinod Kumar, T.; Chandrasekaran, M.; Santhanam, V.; Sudharsan, V. D.

    2017-03-01

    Composites have replaced conventional materials due to their advantages such as low cost, low density, high strength, etc. recently the research has been focused on natural fibers as a suitable replacement for synthetic fibers for reinforcement in composites. Hence, in this work, natural fiber is extracted from palm petiole and this fiber is investigated for reinforcement in epoxy polymer. The fiber is subjected to different chemical treatments for enhancing the surface wetting and Nano cellulose will also be extracted from the fiber. The composite will be fabricated by using handlay-up method by using 1%, 2%, 3% volume fraction of cellulose nanofiber in the epoxy resin. It is observed that the increase of the nanofiber in 3% volume fraction gives the good tensile, flexural and impact strength. So they obtained chemically treated cellulose nanofiber was treated with the amino propyl triethoxysilane and 3% of the silanesilane treated nano-fiber fabricated. Then the mechanical testings of this is compared with the 3% of chemically treated nano-fiber composite. The silane treated nanofiber gives the best results.

  4. Coupling mechanism between wear and oxidation processes of 304 stainless steel in hydrogen peroxide environments.

    Science.gov (United States)

    Dong, Conglin; Yuan, Chengqing; Bai, Xiuqin; Li, Jian; Qin, Honglin; Yan, Xinping

    2017-05-24

    Stainless steel is widely used in strongly oxidizing hydrogen peroxide (H2O2) environments. It is crucial to study its wear behaviour and failure mode. The tribological properties and oxidation of 304 stainless steel were investigated using a MMW-1 tribo-tester with a three-electrode setup in H2O2 solutions with different concentrations. Corrosion current densities (CCDs), coefficients of frictions (COFs), wear mass losses, wear surface topographies, and metal oxide films were analysed and compared. The results show that the wear process and oxidation process interacted significantly with each other. Increasing the concentration of H2O2 or the oxidation time was useful to form a layer of integrated, homogeneous, compact and thick metal oxide film. The dense metal oxide films with higher mechanical strengths improved the wear process and also reduced the oxidation reaction. The wear process removed the metal oxide films to increase the oxidation reaction. Theoretical data is provided for the rational design and application of friction pairs in oxidation corrosion conditions.

  5. Mechanical coupling of microtubule-dependent motor teams during peroxisome transport in Drosophila S2 cells.

    Science.gov (United States)

    De Rossi, María Cecilia; Wetzler, Diana E; Benseñor, Lorena; De Rossi, María Emilia; Sued, Mariela; Rodríguez, Daniela; Gelfand, Vladimir; Bruno, Luciana; Levi, Valeria

    2017-12-01

    Intracellular transport requires molecular motors that step along cytoskeletal filaments actively dragging cargoes through the crowded cytoplasm. Here, we explore the interplay of the opposed polarity motors kinesin-1 and cytoplasmic dynein during peroxisome transport along microtubules in Drosophila S2 cells. We used single particle tracking with nanometer accuracy and millisecond time resolution to extract quantitative information on the bidirectional motion of organelles. The transport performance was studied in cells expressing a slow chimeric plus-end directed motor or the kinesin heavy chain. We also analyzed the influence of peroxisomes membrane fluidity in methyl-β-ciclodextrin treated cells. The experimental data was also confronted with numerical simulations of two well-established tug of war scenarios. The velocity distributions of retrograde and anterograde peroxisomes showed a multimodal pattern suggesting that multiple motor teams drive transport in either direction. The chimeric motors interfered with the performance of anterograde transport and also reduced the speed of the slowest retrograde team. In addition, increasing the fluidity of peroxisomes membrane decreased the speed of the slowest anterograde and retrograde teams. Our results support the existence of a crosstalk between opposed-polarity motor teams. Moreover, the slowest teams seem to mechanically communicate with each other through the membrane to trigger transport. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Investigation of cold extrusion process using coupled thermo-mechanical FEM analysis and adaptive friction modeling

    Science.gov (United States)

    Görtan, Mehmet Okan

    2017-10-01

    Cold extrusion processes are known for their excellent material usage as well as high efficiency in the production of large batches. Although the process starts at room temperature, workpiece temperatures may rise above 200°C. Moreover, contact normal stresses can exceed 2500 MPa, whereas surface enlargement values can reach up to 30. These changes affects friction coefficients in cold extrusion processes. In the current study, friction coefficients between a plain carbon steel C4C (1.0303) and a tool steel (1.2379) are determined dependent on temperature and contact pressure using the sliding compression test (SCT). In order to represent contact normal stress and temperature effects on friction coefficients, an empirical adaptive friction model has been proposed. The validity of the model has been tested with experiments and finite element simulations for a cold forward extrusion process. By using the proposed adaptive friction model together with thermo-mechanical analysis, the deviation in the process loads between numerical simulations and model experiments could be reduced from 18.6% to 3.3%.

  7. A literature review of coupled thermal-hydrologic-mechanical-chemical processes pertinent to the proposed high-level nuclear waste repository at Yucca Mountain

    Energy Technology Data Exchange (ETDEWEB)

    Manteufel, R.D.; Ahola, M.P.; Turner, D.R.; Chowdhury, A.H. [Southwest Research Inst., San Antonio, TX (United States). Center for Nuclear Waste Regulatory Analyses

    1993-07-01

    A literature review has been conducted to determine the state of knowledge available in the modeling of coupled thermal (T), hydrologic (H), mechanical (M), and chemical (C) processes relevant to the design and/or performance of the proposed high-level waste (HLW) repository at Yucca Mountain, Nevada. The review focuses on identifying coupling mechanisms between individual processes and assessing their importance (i.e., if the coupling is either important, potentially important, or negligible). The significance of considering THMC-coupled processes lies in whether or not the processes impact the design and/or performance objectives of the repository. A review, such as reported here, is useful in identifying which coupled effects will be important, hence which coupled effects will need to be investigated by the US Nuclear Regulatory Commission in order to assess the assumptions, data, analyses, and conclusions in the design and performance assessment of a geologic reposit``. Although this work stems from regulatory interest in the design of the geologic repository, it should be emphasized that the repository design implicitly considers all of the repository performance objectives, including those associated with the time after permanent closure. The scope of this review is considered beyond previous assessments in that it attempts with the current state-of-knowledge) to determine which couplings are important, and identify which computer codes are currently available to model coupled processes.

  8. Developing strong concurrent multiphysics multiscale coupling to understand the impact of microstructural mechanisms on the structural scale

    Energy Technology Data Exchange (ETDEWEB)

    Foulk, James W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Alleman, Coleman N. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Mota, Alejandro [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lim, Hojun [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Littlewood, David John [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Bergel, Guy Leshem [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Popova, Evdokia [Georgia Inst. of Technology, Atlanta, GA (United States). Woodruff School of Mechanical Engineering; Montes de Oca Zapiain, David [Georgia Inst. of Technology, Atlanta, GA (United States). Woodruff School of Mechanical Engineering; Kalidindi, Suryanarayana Raju [Georgia Inst. of Technology, Atlanta, GA (United States). Woodruff School of Mechanical Engineering; Ernst, Corey [Elemental Technologies, Provo, UT (United States)

    2017-09-01

    The heterogeneity in mechanical fields introduced by microstructure plays a critical role in the localization of deformation. To resolve this incipient stage of failure, it is therefore necessary to incorporate microstructure with sufficient resolution. On the other hand, computational limitations make it infeasible to represent the microstructure in the entire domain at the component scale. In this study, the authors demonstrate the use of concurrent multi- scale modeling to incorporate explicit, finely resolved microstructure in a critical region while resolving the smoother mechanical fields outside this region with a coarser discretization to limit computational cost. The microstructural physics is modeled with a high-fidelity model that incorporates anisotropic crystal elasticity and rate-dependent crystal plasticity to simulate the behavior of a stainless steel alloy. The component-scale material behavior is treated with a lower fidelity model incorporating isotropic linear elasticity and rate-independent J 2 plas- ticity. The microstructural and component scale subdomains are modeled concurrently, with coupling via the Schwarz alternating method, which solves boundary-value problems in each subdomain separately and transfers solution information between subdomains via Dirichlet boundary conditions. Beyond cases studies in concurrent multiscale, we explore progress in crystal plastic- ity through modular designs, solution methodologies, model verification, and extensions to Sierra/SM and manycore applications. Advances in conformal microstructures having both hexahedral and tetrahedral workflows in Sculpt and Cubit are highlighted. A structure-property case study in two-phase metallic composites applies the Materials Knowledge System to local metrics for void evolution. Discussion includes lessons learned, future work, and a summary of funded efforts and proposed work. Finally, an appendix illustrates the need for two-way coupling through a single degree of

  9. Simulated Space Radiation and Weightlessness: Vascular-Bone Coupling Mechanisms to Preserve Skeletal Health

    Science.gov (United States)

    Alwood, J. S.; Limoli, C. L.; Delp, M. D.; Castillo, A. B.; Globus, R. K.

    2012-01-01

    Weightlessness causes a cephalad fluid shift and reduction in mechanical stimulation, adversely affecting both cortical and trabecular bone tissue in astronauts. In rodent models of weightlessness, the onset of bone loss correlates with reduced skeletal perfusion, reduced and rarified vasculature and lessened vasodilation, which resembles blood-bone symbiotic events that can occur with fracture repair and aging. These are especially serious risks for long term, exploration class missions when astronauts will face the challenge of increased exposure to space radiation and abrupt transitions between different gravity environments upon arrival and return. Previously, we found using the mouse hindlimb unloading model and exposure to heavy ion radiation, both disuse and irradiation cause an acute bone loss that was associated with a reduced capacity to produce bone-forming osteoblasts from the bone marrow. Together, these findings led us to hypothesize that exposure to space radiation exacerbates weightlessness-induced bone loss and impairs recovery upon return, and that treatment with anti-oxidants may mitigate these effects. The specific aims of this recently awarded grant are to: AIM 1 Determine the functional and structural consequences of prolonged weightlessness and space radiation (simulated spaceflight) for bone and skeletal vasculature in the context of bone cell function and oxidative stress. AIM 2 Determine the extent to which an anti-oxidant protects against weightlessness and space radiation-induced bone loss and vascular dysfunction. AIM 3 Determine how space radiation influences later skeletal and vasculature recovery from prolonged weightlessness and the potential of anti-oxidants to preserve adaptive remodeling.

  10. Small wind turbine performance evaluation using field test data and a coupled aero-electro-mechanical model

    Science.gov (United States)

    Wallace, Brian D.

    A series of field tests and theoretical analyses were performed on various wind turbine rotor designs at two Penn State residential-scale wind-electric facilities. This work involved the prediction and experimental measurement of the electrical and aerodynamic performance of three wind turbines; a 3 kW rated Whisper 175, 2.4 kW rated Skystream 3.7, and the Penn State designed Carolus wind turbine. Both the Skystream and Whisper 175 wind turbines are OEM blades which were originally installed at the facilities. The Carolus rotor is a carbon-fiber composite 2-bladed machine, designed and assembled at Penn State, with the intent of replacing the Whisper 175 rotor at the off-grid system. Rotor aerodynamic performance is modeled using WT_Perf, a National Renewable Energy Laboratory developed Blade Element Momentum theory based performance prediction code. Steady-state power curves are predicted by coupling experimentally determined electrical characteristics with the aerodynamic performance of the rotor simulated with WT_Perf. A dynamometer test stand is used to establish the electromechanical efficiencies of the wind-electric system generator. Through the coupling of WT_Perf and dynamometer test results, an aero-electro-mechanical analysis procedure is developed and provides accurate predictions of wind system performance. The analysis of three different wind turbines gives a comprehensive assessment of the capability of the field test facilities and the accuracy of aero-electro-mechanical analysis procedures. Results from this study show that the Carolus and Whisper 175 rotors are running at higher tip-speed ratios than are optimum for power production. The aero-electro-mechanical analysis predicted the high operating tip-speed ratios of the rotors and was accurate at predicting output power for the systems. It is shown that the wind turbines operate at high tip-speeds because of a miss-match between the aerodynamic drive torque and the operating torque of the wind

  11. Probing Kill Mechanisms and Tuning Energetic Biocides

    Science.gov (United States)

    2018-02-01

    attributed to the unique porous inner structure combined with energetic gas generator nitrocellulose which we have previously shown minimizes sintering among...as the temperature increased 373 suggesting that HCl/HOCl is more effective in spore neutralization. HCl and HOCl have unique 374 chemical properties...Disinfection of Bacillus subtilis spore-contaminated surface 512 materials with a sodium hypochlorite and a hydrogen peroxide-based sanitizer, Lett

  12. Intestinal ammonia transport in freshwater and seawater acclimated rainbow trout (Oncorhynchus mykiss): evidence for a Na+ coupled uptake mechanism.

    Science.gov (United States)

    Rubino, Julian G; Zimmer, Alex M; Wood, Chris M

    2015-05-01

    In vitro gut sac experiments were performed on freshwater and 60% seawater acclimated trout (Oncorhynchus mykiss) under treatments designed to discern possible mechanisms of intestinal ammonia transport. Seawater acclimation increased ammonia flux rate into the serosal saline (Jsamm) in the anterior intestine, however it did not alter Jsamm in the mid- or posterior intestine suggesting similar mechanisms of ammonia handling in freshwater and seawater fish. Both fluid transport rate (FTR) and Jsamm were inhibited in response to basolateral ouabain treatment, suggesting a linkage of ammonia uptake to active transport, possibly coupled to fluid transport processes via solvent drag. Furthermore, decreases in FTR and Jsamm caused by low Na(+) treatment indicated a Na(+) linked transport mechanism. Mucosal bumetanide (10(-4) M) had no impact on FTR, yet decreased Jsamm in the anterior and mid-intestine, suggesting NH4(+) substitution for K(+) on an apical NKCC, and at least a partial uncoupling of ammonia transport from fluid transport. Additional treatments (amiloride, 5-(N-ethyl-N-isopropyl)amiloride (EIPA), phenamil, bafilomycin, 4',6-diamidino-2-phenylindole (DAPI), high sodium) intended to disrupt alternative routes of Na(+) uptake yielded no change in FTR or Jsamm, suggesting the absence of direct competition between Na(+) and ammonia for transport. Finally, [(14)C]methylamine permeability (PMA) measurements indicated the likely presence of an intestinal Rh-mediated ammonia transport system, as increasing NH4Cl (0, 1, 5 mmol l(-1)) concentrations reduced PMA, suggesting competition for transport through Rh proteins. Overall, the data presented in this paper provide some of the first insights into mechanisms of teleost intestinal ammonia transport. Copyright © 2014 Elsevier Inc. All rights reserved.

  13. A fully integrated CMOS VCXO-IC with low phase noise, wide tuning range and high tuning linearity

    Science.gov (United States)

    Yanjun, Yang; Yun, Zeng

    2015-06-01

    This paper describes a low phase noise, wide tuning range and high tuning linearity CMOS voltage controlled crystal oscillator IC (VCXO-IC) with LVCMOS and LVPECL output. A differential coupled frequency doubling Colpitts oscillator is adopted to obtain low noise 2× frequency output. Wide tuning range and high linearity are simultaneously achieved by using MOS varactor arrays. The measurement results show that the designed VCXO-IC achieves -134 dBc/Hz phase noise at 1 kHz offset frequency and ± 135 ppm output frequency tuning range within 3% linearity by using 40 MHz fundamental AT-cut crystal. The VCXO-IC is fabricated in the chartered 0.35 μm standard CMOS process and occupies a total silicon area of 2.4 mm2. Project supported by the National Natural Science Foundation of China (No. 61350007).

  14. A Thermo-Hydro-Mechanical coupled Numerical modeling of Injection-induced seismicity on a pre-existing fault

    Science.gov (United States)

    Kim, Jongchan; Archer, Rosalind

    2017-04-01

    In terms of energy development (oil, gas and geothermal field) and environmental improvement (carbon dioxide sequestration), fluid injection into subsurface has been dramatically increased. As a side effect of these operations, a number of injection-induced seismic activities have also significantly risen. It is known that the main causes of induced seismicity are changes in local shear and normal stresses and pore pressure as well. This mechanism leads to increase in the probability of earthquake occurrence on permeable pre-existing fault zones predominantly. In this 2D fully coupled THM geothermal reservoir numerical simulation of injection-induced seismicity, we investigate the thermal, hydraulic and mechanical behavior of the fracture zone, considering a variety of 1) fault permeability, 2) injection rate and 3) injection temperature to identify major contributing parameters to induced seismic activity. We also calculate spatiotemporal variation of the Coulomb stress which is a combination of shear stress, normal stress and pore pressure and lastly forecast the seismicity rate on the fault zone by computing the seismic prediction model of Dieterich (1994).

  15. Coupled Mechanical-Electrochemical-Thermal Modeling for Accelerated Design of EV Batteries; NREL (National Renewable Energy Laboratory)

    Energy Technology Data Exchange (ETDEWEB)

    Pesaran, Ahmad; Zhang, Chao; Kim, Gi-heon; Santhanagopalan, Shriram

    2015-06-10

    The physical and chemical phenomena occurring in a battery are many and complex and in many different scales. Without a better knowledge of the interplay among the multi-physics occurring across the varied scales, it is very challenging and time consuming to design long-lasting, high-performing, safe, affordable large battery systems, enabling electrification of the vehicles and modernization of the grid. The National Renewable Energy Laboratory, a U.S. Department of Energy laboratory, has been developing thermal and electrochemical models for cells and battery packs. Working with software producers, carmakers, and battery developers, computer-aided engineering tools have been developed that can accelerate the electrochemical and thermal design of batteries, reducing time to develop and optimize them and thus reducing the cost of the system. In the past couple of years, we initiated a project to model the mechanical response of batteries to stress, strain, fracture, deformation, puncture, and crush and then link them to electrochemical and thermal models to predict the response of a battery. This modeling is particularly important for understanding the physics and processes that happen in a battery during a crush-inducing vehicle crash. In this paper, we provide an overview of electrochemical-thermal-mechanical models for battery system understanding and designing.

  16. Classical electricity analysis of the coupling mechanisms between admolecule vibrations and localized surface plasmons in STM for vibration detectability

    Science.gov (United States)

    Inaoka, Takeshi; Uehara, Yoich

    2017-08-01

    The presence of a dynamic dipole moment in the gap between the tip of a scanning tunneling microscope (STM) and a substrate, both of which are made of metal, produces a large dynamic dipole moment via the creation of localized surface plasmons (LSPLs). With regard to the vibration-induced structures that have been experimentally observed in STM light emission spectra, we have incorporated the effect of the phonon vibrations of an admolecule below the STM tip into the local response theory, and we have evaluated the enhancement of the dynamic dipole involving phonon vibrations. Our analysis shows how effectively this vibration becomes coupled with the LSPLs. This was shown using three mechanisms that considered the vibrations of a dipole-active molecule and the vibrations of a charged molecule emitting and receiving tunneling electrons. In each of the mechanisms, phonon vibrations with angular frequency ωp shifted each LSPL resonance by ℏωp or by a multiple of ℏωp . The phonon effect was negligibly small when the position of the dipole-active molecule vibrated with ωp, but it was largest and most detectable when the point charge corresponding to the admolecule at the surface of the tip vibrated with ωp. It was found that a series of LSPL resonances with or without phonon-energy shifts can be characterized by a few dominant orders of multipole excitations, and these orders become higher as the resonance energy increases.

  17. Multi-Physics Modelling of Fault Mechanics Using REDBACK: A Parallel Open-Source Simulator for Tightly Coupled Problems

    Science.gov (United States)

    Poulet, Thomas; Paesold, Martin; Veveakis, Manolis

    2017-03-01

    Faults play a major role in many economically and environmentally important geological systems, ranging from impermeable seals in petroleum reservoirs to fluid pathways in ore-forming hydrothermal systems. Their behavior is therefore widely studied and fault mechanics is particularly focused on the mechanisms explaining their transient evolution. Single faults can change in time from seals to open channels as they become seismically active and various models have recently been presented to explain the driving forces responsible for such transitions. A model of particular interest is the multi-physics oscillator of Alevizos et al. (J Geophys Res Solid Earth 119(6), 4558-4582, 2014) which extends the traditional rate and state friction approach to rate and temperature-dependent ductile rocks, and has been successfully applied to explain spatial features of exposed thrusts as well as temporal evolutions of current subduction zones. In this contribution we implement that model in REDBACK, a parallel open-source multi-physics simulator developed to solve such geological instabilities in three dimensions. The resolution of the underlying system of equations in a tightly coupled manner allows REDBACK to capture appropriately the various theoretical regimes of the system, including the periodic and non-periodic instabilities. REDBACK can then be used to simulate the drastic permeability evolution in time of such systems, where nominally impermeable faults can sporadically become fluid pathways, with permeability increases of several orders of magnitude.

  18. High order ADER schemes for a unified first order hyperbolic formulation of Newtonian continuum mechanics coupled with electro-dynamics

    Science.gov (United States)

    Dumbser, Michael; Peshkov, Ilya; Romenski, Evgeniy; Zanotti, Olindo

    2017-11-01

    In this paper, we propose a new unified first order hyperbolic model of Newtonian continuum mechanics coupled with electro-dynamics. The model is able to describe the behavior of moving elasto-plastic dielectric solids as well as viscous and inviscid fluids in the presence of electro-magnetic fields. It is actually a very peculiar feature of the proposed PDE system that viscous fluids are treated just as a special case of elasto-plastic solids. This is achieved by introducing a strain relaxation mechanism in the evolution equations of the distortion matrix A, which in the case of purely elastic solids maps the current configuration to the reference configuration. The model also contains a hyperbolic formulation of heat conduction as well as a dissipative source term in the evolution equations for the electric field given by Ohm's law. Via formal asymptotic analysis we show that in the stiff limit, the governing first order hyperbolic PDE system with relaxation source terms tends asymptotically to the well-known viscous and resistive magnetohydrodynamics (MHD) equations. Furthermore, a rigorous derivation of the model from variational principles is presented, together with the transformation of the Euler-Lagrange differential equations associated with the underlying variational problem from Lagrangian coordinates to Eulerian coordinates in a fixed laboratory frame. The present paper hence extends the unified first order hyperbolic model of Newtonian continuum mechanics recently proposed in [110,42] to the more general case where the continuum is coupled with electro-magnetic fields. The governing PDE system is symmetric hyperbolic and satisfies the first and second principle of thermodynamics, hence it belongs to the so-called class of symmetric hyperbolic thermodynamically compatible systems (SHTC), which have been studied for the first time by Godunov in 1961 [61] and later in a series of papers by Godunov and Romenski [67,69,119]. An important feature of the

  19. QM/MM study of the C-C coupling reaction mechanism of CYP121, an essential Cytochrome p450 of Mycobacterium tuberculosis

    OpenAIRE

    Dumas, Victoria Gisel; Defelipe, Lucas Alfredo; Petruk, Ariel Alcides; Turjanski, Adrian; Marti, Marcelo Adrian

    2016-01-01

    Among 20 p450s of Mycobacterium tuberculosis (Mt), CYP121 has received an outstanding interest, not only due to its essentiality for bacterial viability but also because it catalyzes an unusual carbon-carbon coupling reaction. Based on the structure of the substrate bound enzyme, several reaction mechanisms were proposed involving first Tyr radical formation, second Tyr radical formation, and C?C coupling. Key and unknown features, being the nature of the species that generate the first and s...

  20. Male and Couple Fertility Impairment due to HPV-DNA Sperm Infection: Update on Molecular Mechanism and Clinical Impact—Systematic Review

    OpenAIRE

    Salvatore Gizzo; Bruno Ferrari; Marco Noventa; Emanuele Ferrari; Tito Silvio Patrelli; Michele Gangemi; Giovanni Battista Nardelli

    2014-01-01

    Recent evidences identify Human Papillomavirus (HPV) sperm infection as a possible cause of male and couple infertility. It acts through different mechanisms at various steps of human conception and early gestational development. We performed a systematic review to assess the role of HPV semen infection on male and couple infertility. Analysis of available and eligible data does not permit us to fund clear evidences about clinical impact of HPV infection on fertility, although sperm parameter...

  1. Using a coupled hydro-mechanical fault model to better understand the risk of induced seismicity in deep geothermal projects

    Science.gov (United States)

    Abe, Steffen; Krieger, Lars; Deckert, Hagen

    2017-04-01

    The changes of fluid pressures related to the injection of fluids into the deep underground, for example during geothermal energy production, can potentially reactivate faults and thus cause induced seismic events. Therefore, an important aspect in the planning and operation of such projects, in particular in densely populated regions such as the Upper Rhine Graben in Germany, is the estimation and mitigation of the induced seismic risk. The occurrence of induced seismicity depends on a combination of hydraulic properties of the underground, mechanical and geometric parameters of the fault, and the fluid injection regime. In this study we are therefore employing a numerical model to investigate the impact of fluid pressure changes on the dynamics of the faults and the resulting seismicity. The approach combines a model of the fluid flow around a geothermal well based on a 3D finite difference discretisation of the Darcy-equation with a 2D block-slider model of a fault. The models are coupled so that the evolving pore pressure at the relevant locations of the hydraulic model is taken into account in the calculation of the stick-slip dynamics of the fault model. Our modelling approach uses two subsequent modelling steps. Initially, the fault model is run by applying a fixed deformation rate for a given duration and without the influence of the hydraulic model in order to generate the background event statistics. Initial tests have shown that the response of the fault to hydraulic loading depends on the timing of the fluid injection relative to the seismic cycle of the fault. Therefore, multiple snapshots of the fault's stress- and displacement state are generated from the fault model. In a second step, these snapshots are then used as initial conditions in a set of coupled hydro-mechanical model runs including the effects of the fluid injection. This set of models is then compared with the background event statistics to evaluate the change in the probability of

  2. Vibroacoustic modeling of an acoustic resonator tuned by dielectric elastomer membrane with voltage control

    Science.gov (United States)

    Yu, Xiang; Lu, Zhenbo; Cheng, Li; Cui, Fangsen

    2017-01-01

    This paper investigates the acoustic properties of a duct resonator tuned by an electro-active membrane. The resonator takes the form of a side-branch cavity which is attached to a rigid duct and covered by a pre-stretched Dielectric Elastomer (DE) in the neck area. A three-dimensional, analytical model based on the sub-structuring approach is developed to characterize the complex structure-acoustic coupling between the DE membrane and its surrounding acoustic media. We show that such resonator provides sound attenuation in the medium frequency range mainly by means of sound reflection, as a result of the membrane vibration. The prediction accuracy of the proposed model is validated against experimental test. The pre-stretched DE membrane with fixed edges responds to applied voltage change with a varying inner stress and, by the same token, its natural frequency and vibrational response can be tuned to suit particular frequencies of interest. The peaks in the transmission loss (TL) curves can be shifted towards lower frequencies when the voltage applied to the DE membrane is increased. Through simulations on the effect of increasing the voltage level, the TL shifting mechanism and its possible tuning range are analyzed. This paves the way for applying such resonator device for adaptive-passive noise control.

  3. Transient Torsional Analysis of a Belt Conveyor Drive with Pneumatic Flexible Shaft Coupling

    Directory of Open Access Journals (Sweden)

    Kaššay Peter

    2017-03-01

    Full Text Available Development and application of pneumatic flexible shaft couplings have been in the center of our department research activities for a long time. These couplings are able to change torsional stiffness by changing pressure in their flexible elements – air bellows. Until now we have dealt with the use of pneumatic flexible shaft couplings for tuning mechanical systems working with periodically alternating load torque at steady state. Some mechanical systems, however, operate with a static load torque at constant speed (e.g. hoists, elevators, etc., where it is necessary to consider the suitability of shaft coupling in terms of load torque at transient conditions (run-up and braking. Therefore we decided to analyze the use of pneumatic flexible shaft couplings also in this type of mechanical systems on an example of conveyor belt drive.

  4. Tuning The Laser Heater Undulator

    Energy Technology Data Exchange (ETDEWEB)

    Wolf, Zackary

    2010-12-03

    The laser heater undulator for the LCLS requires different tuning techniques than the main undulators. It is a pure permanent magnet (PPM) undulator, rather than the hybrid design of the main undulators. The PPM design allows analytic calculation of the undulator fields. The calculations let errors be introduced and correction techniques be derived. This note describes how the undulator was modelled, and the methods which were found to correct potential errors in the undulator. The laser heater undulator for the LCLS is a pure permanent magnet device requiring different tuning techniques than the main undulators. In this note, the laser heater undulator is modelled and tuning techniques to compensate various errors are derived.

  5. Biophysical comparison of ATP-driven proton pumping mechanisms suggests a kinetic advantage for the rotary process depending on coupling ratio.

    Science.gov (United States)

    Anandakrishnan, Ramu; Zuckerman, Daniel M

    2017-01-01

    ATP-driven proton pumps, which are critical to the operation of a cell, maintain cytosolic and organellar pH levels within a narrow functional range. These pumps employ two very different mechanisms: an elaborate rotary mechanism used by V-ATPase H+ pumps, and a simpler alternating access mechanism used by P-ATPase H+ pumps. Why are two different mechanisms used to perform the same function? Systematic analysis, without parameter fitting, of kinetic models of the rotary, alternating access and other possible mechanisms suggest that, when the ratio of protons transported per ATP hydrolyzed exceeds one, the one-at-a-time proton transport by the rotary mechanism is faster than other possible mechanisms across a wide range of driving conditions. When the ratio is one, there is no intrinsic difference in the free energy landscape between mechanisms, and therefore all mechanisms can exhibit the same kinetic performance. To our knowledge all known rotary pumps have an H+:ATP ratio greater than one, and all known alternating access ATP-driven proton pumps have a ratio of one. Our analysis suggests a possible explanation for this apparent relationship between coupling ratio and mechanism. When the conditions under which the pump must operate permit a coupling ratio greater than one, the rotary mechanism may have been selected for its kinetic advantage. On the other hand, when conditions require a coupling ratio of one or less, the alternating access mechanism may have been selected for other possible advantages resulting from its structural and functional simplicity.

  6. Classical Electrodynamics Coupled to Quantum Mechanics for Calculation of Molecular Optical Properties: a RT-TDDFT/FDTD Approach

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Hanning; McMahon, J. M.; Ratner, Mark A.; Schatz, George C.

    2010-09-02

    A new multiscale computational methodology was developed to effectively incorporate the scattered electric field of a plasmonic nanoparticle into a quantum mechanical (QM) optical property calculation for a nearby dye molecule. For a given location of the dye molecule with respect to the nanoparticle, a frequency-dependent scattering response function was first determined by the classical electrodynamics (ED) finite-difference time-domain (FDTD) approach. Subsequently, the time-dependent scattered electric field at the dye molecule was calculated using the FDTD scattering response function through a multidimensional Fourier transform to reflect the effect of polarization of the nanoparticle on the local field at the molecule. Finally, a real-time time-dependent density function theory (RT-TDDFT) approach was employed to obtain a desired optical property (such as absorption cross section) of the dye molecule in the presence of the nanoparticle’s scattered electric field. Our hybrid QM/ED methodology was demonstrated by investigating the absorption spectrum of the N3 dye molecule and the Raman spectrum of pyridine, both of which were shown to be significantly enhanced by a 20 nm diameter silver sphere. In contrast to traditional quantum mechanical optical calculations in which the field at the molecule is entirely determined by intensity and polarization direction of the incident light, in this work we show that the light propagation direction as well as polarization and intensity are important to nanoparticle-bound dye molecule response. At no additional computation cost compared to conventional ED and QM calculations, this method provides a reliable way to couple the response of the dye molecule’s individual electrons to the collective dielectric response of the nanoparticle.

  7. Physical-biological coupling induced aggregation mechanism for the formation of high biomass red tides in low nutrient waters.

    Science.gov (United States)

    Lai, Zhigang; Yin, Kedong

    2014-01-01

    Port Shelter is a semi-enclosed bay in northeast Hong Kong where high biomass red tides are observed to occur frequently in narrow bands along the local bathymetric isobars. Previous study showed that nutrients in the Bay are not high enough to support high biomass red tides. The hypothesis is that physical aggregation and vertical migration of dinoflagellates appear to be the driving mechanism to promote the formation of red tides in this area. To test this hypothesis, we used a high-resolution estuarine circulation model to simulate the near-shore water dynamics based on in situ measured temperature/salinity profiles, winds and tidal constitutes taken from a well-validated regional tidal model. The model results demonstrated that water convergence occurs in a narrow band along the west shore of Port Shelter under a combined effect of stratified tidal current and easterly or northeasterly wind. Using particles as dinoflagellate cells and giving diel vertical migration, the model results showed that the particles aggregate along the convergent zone. By tracking particles in the model predicted current field, we estimated that the physical-biological coupled processes induced aggregation of the particles could cause 20-45 times enhanced cell density in the convergent zone. This indicated that a high cell density red tide under these processes could be initialized without very high nutrients concentrations. This may explain why Port Shelter, a nutrient-poor Bay, is the hot spot for high biomass red tides in Hong Kong in the past 25 years. Our study explains why red tide occurrences are episodic events and shows the importance of taking the physical-biological aggregation mechanism into consideration in the projection of red tides for coastal management. Copyright © 2013 Elsevier B.V. All rights reserved.

  8. A Coupled Experiment-finite Element Modeling Methodology for Assessing High Strain Rate Mechanical Response of Soft Biomaterials.

    Science.gov (United States)

    Prabhu, Rajkumar; Whittington, Wilburn R; Patnaik, Sourav S; Mao, Yuxiong; Begonia, Mark T; Williams, Lakiesha N; Liao, Jun; Horstemeyer, M F

    2015-05-18

    This study offers a combined experimental and finite element (FE) simulation approach for examining the mechanical behavior of soft biomaterials (e.g. brain, liver, tendon, fat, etc.) when exposed to high strain rates. This study utilized a Split-Hopkinson Pressure Bar (SHPB) to generate strain rates of 100-1,500 sec(-1). The SHPB employed a striker bar consisting of a viscoelastic material (polycarbonate). A sample of the biomaterial was obtained shortly postmortem and prepared for SHPB testing. The specimen was interposed between the incident and transmitted bars, and the pneumatic components of the SHPB were activated to drive the striker bar toward the incident bar. The resulting impact generated a compressive stress wave (i.e. incident wave) that traveled through the incident bar. When the compressive stress wave reached the end of the incident bar, a portion continued forward through the sample and transmitted bar (i.e. transmitted wave) while another portion reversed through the incident bar as a tensile wave (i.e. reflected wave). These waves were measured using strain gages mounted on the incident and transmitted bars. The true stress-strain behavior of the sample was determined from equations based on wave propagation and dynamic force equilibrium. The experimental stress-strain response was three dimensional in nature because the specimen bulged. As such, the hydrostatic stress (first invariant) was used to generate the stress-strain response. In order to extract the uniaxial (one-dimensional) mechanical response of the tissue, an iterative coupled optimization was performed using experimental results and Finite Element Analysis (FEA), which contained an Internal State Variable (ISV) material model used for the tissue. The ISV material model used in the FE simulations of the experimental setup was iteratively calibrated (i.e. optimized) to the experimental data such that the experiment and FEA strain gage values and first invariant of stresses were in

  9. Analysis of tuning methods in semiconductor frequency-selective surfaces

    Science.gov (United States)

    Shemelya, Corey; Palm, Dominic; Fip, Tassilo; Rahm, Marco

    2017-02-01

    Advanced technology, such as sensing and communication equipment, has recently begun to combine optically sensitive nano-scale structures with customizable semiconductor material systems. Included within this broad field of study is the aptly named frequency-selective surface; which is unique in that it can be artificially designed to produce a specific electromagnetic or optical response. With the inherent utility of a frequency-selective surface, there has been an increased interest in the area of dynamic frequency-selective surfaces, which can be altered through optical or electrical tuning. This area has had exciting break throughs as tuning methods have evolved; however, these methods are typically energy intensive (optical tuning) or have met with limited success (electrical tuning). As such, this work investigates multiple structures and processes which implement semiconductor electrical biasing and/or optical tuning. Within this study are surfaces ranging from transmission meta-structures to metamaterial surface-waves and the associated coupling schemes. This work shows the utility of each design, while highlighting potential methods for optimizing dynamic meta-surfaces. As an added constraint, the structures were also designed to operate in unison with a state-of-the-art Ti:Sapphire Spitfire Ace and Spitfire Ace PA dual system (12 Watt) with pulse front matching THz generation and an EOS detection system. Additionally, the Ti:Sapphire laser system would provide the means for optical tunablity, while electrical tuning can be obtained through external power supplies.

  10. Tuning and backreaction in F-term axion monodromy inflation

    Directory of Open Access Journals (Sweden)

    Arthur Hebecker

    2015-05-01

    Full Text Available We continue the development of axion monodromy inflation, focusing in particular on the backreaction of complex structure moduli. In our setting, the shift symmetry comes from a partial large complex structure limit of the underlying type IIB orientifold or F-theory fourfold. The coefficient of the inflaton term in the superpotential has to be tuned small to avoid conflict with Kähler moduli stabilisation. To allow such a tuning, this coefficient necessarily depends on further complex structure moduli. At large values of the inflaton field, these moduli are then in danger of backreacting too strongly. To avoid this, further tunings are necessary. In weakly coupled type IIB theory at the orientifold point, implementing these tunings appears to be difficult if not impossible. However, fourfolds or models with mobile D7-branes provide enough structural freedom. We calculate the resulting inflaton potential and study the feasibility of the overall tuning given the limited freedom of the flux landscape. Our preliminary investigations suggest that, even imposing all tuning conditions, the remaining choice of flux vacua can still be large enough for such models to provide a promising path to large-field inflation in string theory.

  11. Electro-chemo-hydro-mechanical coupling in clayey media; Couplage electro-chimio-hydro-mecaniques dans les milieux argileux

    Energy Technology Data Exchange (ETDEWEB)

    Lemaire, Th

    2004-12-15

    The aim of this study is to understand coupled phenomena that occur in swelling porous materials like clays. Electro-chemo-hydro-mechanical contributions are taken into account to analyze transfers in such minerals. In a first part, a general discussion is proposed to introduce mineralogical and physico- chemical considerations of clayey media. An important objective of this chapter is to show the crucial role of the microstructure. In a second part is presented an imbibition test in a MX80 bentonite powder. The hydraulic diffusivity versus water content curve's decrease is explained thanks to a double porosity model that shows the progressive collapse of meso-pores due to swelling effects at the micro-scale. Thus a multi-scale analysis is necessary to well describe clayey media behaviour. The third chapter exposes such a multi-scale modelling (periodic homogenization). It is based on the double-layer theory and introduces an innovative concept of virtual electrolyte solution. First numerical results are given in a simple geometry (parallel platelets). In the next part are proposed numerical simulations of two kinds: response of the system to a chemical gradient and simulation of electro-osmosis. The end of this chapter puts into relief the necessity to integrate pH effects in the model. In the last part, chemical surface exchanges are incorporated in the modelling to understand pH and ionic force roles in electro-osmotic process. (author)

  12. Fully Hydro-Mechanically Coupled Experiments and Simulations on Rough Fractures Subjected to High-Pressure Fluid Injection

    Science.gov (United States)

    Vogler, D.; Settgast, R.; Annavarapu, C.; Madonna, C.; Bayer, P.; Amann, F.

    2016-12-01

    This work presents fully hydro-mechanically coupled experiments and simulations in heterogeneous fractures. Cylindrical specimens with an artificial fracture normal to the cylinder axis were axially loaded to evaluate: (i) fracture normal closure; (ii) fracture contact stress evolution; and (iii) fracture normal closure and fluid injection pressure response. The laboratory experiments were simulated with the GEOS framework, which captures the non-linear behavior of fracture normal closure and fluid pressure response. To apply the developed model on the field scale, a heterogeneous fracture aperture field is created from aperture data recorded under zero-stress on natural tensile fractures from the Grimsel Test Site (GTS), Switzerland. The field stresses measured in the GTS are applied on the model domain, yielding the unique aperture distribution and stress perturbations in the rock mass associated with the applied stress state. Next, fluid is injected into the fracture center and tortuous flow channeling is observed. Increasing fluid injection pressures result in localized fracture opening, which leads to an increasingly non-linear relationship between fluid injection flow rate and pressure.

  13. Confronting electroweak fine-tuning with No-Scale Supergravity

    Directory of Open Access Journals (Sweden)

    Tristan Leggett

    2015-01-01

    Full Text Available Applying No-Scale Supergravity boundary conditions at a heavy unification scale to the Flipped SU(5 grand unified theory with extra TeV-scale vector-like multiplets, i.e. No-Scale F-SU(5, we express the Z-boson mass MZ as an explicit function of the boundary gaugino mass M1/2, MZ2=MZ2(M1/22, with implicit dependence upon a dimensionless ratio c of the supersymmetric Higgs mixing parameter μ and M1/2. Setting the top Yukawa coupling consistent with mt=174.3 GeV at MZ=91.2 GeV, the value of c naturally tends toward c≃1, which indirectly suggests underlying action of the Giudice–Masiero mechanism. Proportional dependence of all model scales upon the unified gaugino mass M1/2 in the No-Scale F-SU(5 model suggests one possible mechanism of confronting the electroweak fine-tuning problem.

  14. Abnormal Left Ventricular Mechanics of Ventricular Ectopic Beats: Insights into Origin and Coupling Interval in Premature Ventricular Contraction-Induced Cardiomyopathy

    Science.gov (United States)

    Potfay, Jonathan; Kaszala, Karoly; Tan, Alex Y.; Sima, Adam P.; Gorcsan, John; Ellenbogen, Kenneth A.; Huizar, Jose F.

    2015-01-01

    Background Left ventricular (LV) dyssynchrony caused by premature ventricular contractions (PVCs) has been proposed as a mechanism of PVC-induced cardiomyopathy (CM). We sought to understand the impact of different PVC locations and coupling intervals (prematurity) on LV regional mechanics and global function of the PVC beat itself. Methods and Results Using our premature pacing algorithm, pentageminal PVCs at coupling intervals of 200–375ms were delivered from the epicardial right ventricular (RV) apex, RV outflow tract (RVOT), and LV free wall, as well as premature atrial contractions (PACs) from the left atrial (LA) appendage at a coupling interval of 200ms in seven healthy canines. LV short axis echocardiographic images, LV stroke volume (SV) and dP/dtmax were obtained during all ectopic beats and VP. LV dyssynchrony was assessed by dispersion of QRS-to-peak strain (earliest – last QRS-to-peak strain) between 6 different LV segments during each of the aforementioned beats (GE, EchoPac). LV dyssynchrony was greater during long- rather than short-coupled PVCs and PVCs at 375ms compared with rapid VP at 400ms (P<0.0001), whereas, no difference was found between PVC locations. Longer PVC coupling intervals were associated with greater SV and dP/dtmax despite more pronounced dyssynchrony (P<0.001). Conclusions PVCs with longer coupling intervals demonstrate more pronounced LV dyssynchrony, whereas PVC location has minimal impact. LV dyssynchrony cannot be attributed to prematurity or abnormal ventricular activation alone, but rather to a combination of both. This study suggests that late-coupled PVCs may cause a more severe cardiomyopathy if dyssynchrony is the leading mechanism responsible for PVC-induced CM. PMID:26297787

  15. Mechanism of the Suzuki–Miyaura Cross-Coupling Reaction Mediated by [Pd(NHC)(allyl)Cl] Precatalysts

    KAUST Repository

    Meconi, Giulia Magi

    2017-05-24

    Density functional theory calculations have been used to investigate the activation mechanism for the precatalyst series [Pd]-X-1–4 derived from [Pd(IPr)(R-allyl)X] species by substitutions at the terminal position of the allyl moiety ([Pd] = Pd(IPr); R = H (1), Me (2), gem-Me2 (3), Ph (4), X = Cl, Br). Next, we have investigated the Suzuki–Miyaura cross-coupling reaction for the active catalyst species IPr-Pd(0) using 4-chlorotoluene and phenylboronic acid as substrates and isopropyl alcohol as a solvent. Our theoretical findings predict an upper barrier trend, corresponding to the activation mechanism for the [Pd]-Cl-1–4 series, in good agreement with the experiments. They indeed provide a quantitative explanation of the low yield (12%) displayed by [Pd]-Cl-1 species (ΔG⧧ ≈ 30.0 kcal/mol) and of the high yields (≈90%) observed in the case of [Pd]-Cl-2–4 complexes (ΔG⧧ ≈ 20.0 kcal/mol). Additionally, the studied Suzuki–Miyaura reaction involving the IPr-Pd(0) species is calculated to be thermodynamically favorable and kinetically facile. Similar investigations for the [Pd]-Br-1–4 series, derived from [Pd(IPr)(R-allyl)Br], indicate that the oxidative addition step for IPr-Pd(0)-mediated catalysis with 4-bromotoluene is kinetically more favored than that with 4-chlorotoluene. Finally, we have explored the potential of Ni-based complexes [Ni((IPr)(R-allyl)X] (X = Cl, Br) as Suzuki–Miyaura reaction catalysts. Apart from a less endergonic reaction energy profile for both precatalyst activation and catalytic cycle, a steep increase in the predicted upper energy barriers (by 2.0–15.0 kcal/mol) is calculated in the activation mechanism for the [Ni]-X-1–4 series compared to the [Pd]-X-1–4 series. Overall, these results suggest that Ni-based precatalysts are expected to be less active than the Pd-based precatalysts for the studied Suzuki–Miyaura reaction.

  16. NMC and the Fine-Tuning Problem on the Brane

    Directory of Open Access Journals (Sweden)

    A. Safsafi

    2014-01-01

    Full Text Available We propose a new solution to the fine-tuning problem related to coupling constant λ of the potential. We study a quartic potential of the form λϕ4 in the framework of the Randall-Sundrum type II braneworld model in the presence of a Higgs field which interacts nonminimally with gravity via a possible interaction term of the form -(ξ/2ϕ2R. Using the conformal transformation techniques, the slow-roll parameters in high energy limit are reformulated in the case of a nonminimally coupled scalar field. We show that, for some value of a coupling parameter ξ and brane tension T, we can eliminate the fine-tuning problem. Finally, we present graphically the solutions of several values of the free parameters of the model.

  17. Chimera states in mechanical oscillator networks

    DEFF Research Database (Denmark)

    Martens, Erik Andreas; Thutupalli, Shashi; Fourrière, Antoine

    2013-01-01

    of whether chimeras are indeed characteristic of natural systems. This calls for a palpable realization of chimera states without any fine-tuning, from which physical mechanisms underlying their emergence can be uncovered. Here, we devise a simple experiment with mechanical oscillators coupled...... in our experiments is controlled by elementary dynamical equations from mechanics that are ubiquitous in many natural and technological systems. The symmetry-breaking mechanism revealed by our experiments may thus be prevalent in systems exhibiting collective behavior, such as power grids, optomechanical...

  18. On non-linear dynamics of coupled 1+1DOF versus 1+1/2DOF Electro-Mechanical System

    DEFF Research Database (Denmark)

    Darula, Radoslav; Sorokin, Sergey

    2014-01-01

    or the first order differential equation (or a set of equations) for electrical system, depending on properties of the electrical circuit. For the sake of brevity, we assume a 1DOF mechanical system, coupled to 1 or 1/2DOF electrical system (depending whether the capacitance is, or is not considered...

  19. Low noise tuned amplifier

    Science.gov (United States)

    Kleinberg, L. L. (Inventor)

    1984-01-01

    A bandpass amplifier employing a field effect transistor amplifier first stage is described with a resistive load either a.c. or directly coupled to the non-inverting input of an operational amplifier second stage which is loaded in a Wien Bridge configuration. The bandpass amplifier may be operated with a signal injected into the gate terminal of the field effect transistor and the signal output taken from the output terminal of the operational amplifier. The operational amplifier stage appears as an inductive reactance, capacitive reactance and negative resistance at the non-inverting input of the operational amplifier, all of which appear in parallel with the resistive load of the field effect transistor.

  20. Gain and frequency tuning within the mouse cochlear apex

    Energy Technology Data Exchange (ETDEWEB)

    Oghalai, John S.; Raphael, Patrick D. [Department of Otolaryngology, Stanford University School of Medicine, Stanford, California (United States); Gao, Simon [Department of Otolaryngology, Stanford University School of Medicine, Stanford, California (United States); Department of Bioengineering, Rice University, Houston, Texas (United States); Lee, Hee Yoon [Department of Otolaryngology, Stanford University School of Medicine, Stanford, California (United States); Department of Electrical Engineering, Stanford University, Stanford, California (United States); Groves, Andrew K. [Department of Neuroscience, Department of Molecular and Human Genetics, and Program in Developmental Biology, Baylor College of Medicine, Houston, Texas (United States); Zuo, Jian [Department of Developmental Neurobiology, St. Jude Children’s Research Hospital, Memphis, Tennessee (United States); Applegate, Brian E. [Department of Biomedical Engineering, Texas A& M University, College Station, Texas (United States)

    2015-12-31

    Normal mammalian hearing requires cochlear outer hair cell active processes that amplify the traveling wave with high gain and sharp tuning, termed cochlear amplification. We have used optical coherence tomography to study cochlear amplification within the apical turn of the mouse cochlea. We measured not only classical basilar membrane vibratory tuning curves but also vibratory responses from the rest of the tissues that compose the organ of Corti. Basilar membrane tuning was sharp in live mice and broad in dead mice, whereas other regions of the organ of Corti demonstrated phase shifts consistent with additional filtering beyond that provided by basilar membrane mechanics. We use these experimental data to support a conceptual framework of how cochlear amplification is tuned within the mouse cochlear apex. We will also study transgenic mice with targeted mutations that affect different biomechanical aspects of the organ of Corti in an effort to localize the underlying processes that produce this additional filtering.

  1. Centennial-scale climate change from decadally-paced explosive volcanism: a coupled sea ice-ocean mechanism

    Science.gov (United States)

    Zhong, Y.; Miller, G. H.; Otto-Bliesner, B. L.; Holland, M. M.; Bailey, D. A.; Schneider, D. P.; Geirsdottir, A.

    2011-12-01

    Northern Hemisphere summer cooling through the Holocene is largely driven by the steady decrease in summer insolation tied to the precession of the equinoxes. However, centennial-scale climate departures, such as the Little Ice Age, must be caused by other forcings, most likely explosive volcanism and changes in solar irradiance. Stratospheric volcanic aerosols have the stronger forcing, but their short residence time likely precludes a lasting climate impact from a single eruption. Decadally paced explosive volcanism may produce a greater climate impact because the long response time of ocean surface waters allows for a cumulative decrease in sea-surface temperatures that exceeds that of any single eruption. Here we use a global climate model to evaluate the potential long-term climate impacts from four decadally paced large tropical eruptions. Direct forcing results in a rapid expansion of Arctic Ocean sea ice that persists throughout the eruption period. The expanded sea ice increases the flux of sea ice exported to the northern North Atlantic long enough that it reduces the convective warming of surface waters in the subpolar North Atlantic. In two of our four simulations the cooler surface waters being advected into the Arctic Ocean reduced the rate of basal sea-ice melt in the Atlantic sector of the Arctic Ocean, allowing sea ice to remain in an expanded state for > 100 model years after volcanic aerosols were removed from the stratosphere. In these simulations the coupled sea ice-ocean mechanism maintains the strong positive feedbacks of an expanded Arctic Ocean sea ice cover, allowing the initial cooling related to the direct effect of volcanic aerosols to be perpetuated, potentially resulting in a centennial-scale or longer change of state in Arctic climate. The fact that the sea ice-ocean mechanism was not established in two of our four simulations suggests that a long-term sea ice response to volcanic forcing is sensitive to the stability of the seawater

  2. A progress report for the large block test of the coupled thermal-mechanical-hydrological-chemical processes

    Energy Technology Data Exchange (ETDEWEB)

    Lin, W.; Wilder, D.G.; Blink, J. [and others

    1994-10-01

    This is a progress report on the Large Block Test (LBT) project. The purpose of the LBT is to study some of the coupled thermal-mechanical-hydrological-chemical (TMHC) processes in the near field of a nuclear waste repository under controlled boundary conditions. To do so, a large block of Topopah Spring tuff will be heated from within for about 4 to 6 months, then cooled down for about the same duration. Instruments to measure temperature, moisture content, stress, displacement, and chemical changes will be installed in three directions in the block. Meanwhile, laboratory tests will be conducted on small blocks to investigate individual thermal-mechanical, thermal-hydrological, and thermal-chemical processes. The fractures in the large block will be characterized from five exposed surfaces. The minerals on fracture surfaces will be studied before and after the test. The results from the LBT will be useful for testing and building confidence in models that will be used to predict TMHC processes in a repository. The boundary conditions to be controlled on the block include zero moisture flux and zero heat flux on the sides, constant temperature on the top, and constant stress on the outside surfaces of the block. To control these boundary conditions, a load-retaining frame is required. A 3 x 3 x 4.5 m block of Topopah Spring tuff has been isolated on the outcrop at Fran Ridge, Nevada Test Site. Pre-test model calculations indicate that a permeability of at least 10{sup -15} m{sup 2} is required so that a dryout zone can be created within a practical time frame when the block is heated from within. Neutron logging was conducted in some of the vertical holes to estimate the initial moisture content of the block. It was found that about 60 to 80% of the pore volume of the block is saturated with water. Cores from the vertical holes have been used to map the fractures and to determine the properties of the rock. A current schedule is included in the report.

  3. Centennial-scale climate change from decadally-paced explosive volcanism: a coupled sea ice-ocean mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Zhong, Y. [University of Colorado, INSTAAR, Boulder, CO (United States); Miller, G.H. [University of Colorado, INSTAAR, Boulder, CO (United States); University of Colorado, Department of Geological Sciences, Boulder, CO (United States); Otto-Bliesner, B.L.; Holland, M.M.; Bailey, D.A. [NCAR, Boulder, CO (United States); Schneider, D.P. [NCAR, Boulder, CO (United States); University of Colorado, CIRES, Boulder, CO (United States); Geirsdottir, A. [University of Iceland, Department of Earth Sciences and Institute of Earth Sciences, Reykjavik (Iceland)

    2011-12-15

    Northern Hemisphere summer cooling through the Holocene is largely driven by the steady decrease in summer insolation tied to the precession of the equinoxes. However, centennial-scale climate departures, such as the Little Ice Age, must be caused by other forcings, most likely explosive volcanism and changes in solar irradiance. Stratospheric volcanic aerosols have the stronger forcing, but their short residence time likely precludes a lasting climate impact from a single eruption. Decadally paced explosive volcanism may produce a greater climate impact because the long response time of ocean surface waters allows for a cumulative decrease in sea-surface temperatures that exceeds that of any single eruption. Here we use a global climate model to evaluate the potential long-term climate impacts from four decadally paced large tropical eruptions. Direct forcing results in a rapid expansion of Arctic Ocean sea ice that persists throughout the eruption period. The expanded sea ice increases the flux of sea ice exported to the northern North Atlantic long enough that it reduces the convective warming of surface waters in the subpolar North Atlantic. In two of our four simulations the cooler surface waters being advected into the Arctic Ocean reduced the rate of basal sea-ice melt in the Atlantic sector of the Arctic Ocean, allowing sea ice to remain in an expanded state for > 100 model years after volcanic aerosols were removed from the stratosphere. In these simulations the coupled sea ice-ocean mechanism maintains the strong positive feedbacks of an expanded Arctic Ocean sea ice cover, allowing the initial cooling related to the direct effect of volcanic aerosols to be perpetuated, potentially resulting in a centennial-scale or longer change of state in Arctic climate. The fact that the sea ice-ocean mechanism was not established in two of our four simulations suggests that a long-term sea ice response to volcanic forcing is sensitive to the stability of the seawater

  4. Mechanics of the foot Part 2: A coupled solid-fluid model to investigate blood transport in the pathologic foot.

    Science.gov (United States)

    Mithraratne, K; Ho, H; Hunter, P J; Fernandez, J W

    2012-10-01

    A coupled computational model of the foot consisting of a three-dimensional soft tissue continuum and a one-dimensional (1D) transient blood flow network is presented in this article. The primary aim of the model is to investigate the blood flow in major arteries of the pathologic foot where the soft tissue stiffening occurs. It has been reported in the literature that there could be up to about five-fold increase in the mechanical stiffness of the plantar soft tissues in pathologic (e.g. diabetic) feet compared with healthy ones. The increased stiffness results in higher tissue hydrostatic pressure within the plantar area of the foot when loaded. The hydrostatic pressure acts on the external surface of blood vessels and tend to reduce the flow cross-section area and hence the blood supply. The soft tissue continuum model of the foot was modelled as a tricubic Hermite finite element mesh representing all the muscles, skin and fat of the foot and treated as incompressible with transversely isotropic properties. The details of the mechanical model of soft tissue are presented in the companion paper, Part 1. The deformed state of the soft tissue continuum because of the applied ground reaction force at three foot positions (heel-strike, midstance and toe-off) was obtained by solving the Cauchy equations based on the theory of finite elasticity using the Galerkin finite element method. The geometry of the main arterial network in the foot was represented using a 1D Hermite cubic finite element mesh. The flow model consists of 1D Navier-Stokes equations and a nonlinear constitutive equation to describe vessel radius-transmural pressure relation. The latter was defined as the difference between the fluid and soft tissue hydrostatic pressure. Transient flow governing equations were numerically solved using the two-step Lax-Wendroff finite difference method. The geometry of both the soft tissue continuum and arterial network is anatomically-based and was developed using

  5. Mechanism of the interannual oscillation in length of day and its constraint on the electromagnetic coupling at the core-mantle boundary

    Science.gov (United States)

    Duan, Pengshuo; Liu, Genyou; Hu, Xiaogang; Zhao, Jin; Huang, Chengli

    2018-01-01

    A significant 6 yr oscillation exists in the length of day (LOD) on the interannual scales. There are mainly two models currently to explain this oscillation, i.e., mantle-inner core gravitational (MICG) coupling mode and the fast torsional waves within the fluid outer core. The former has been doubted, while the source of the excitation of the latter is not yet understood. Therefore, the mechanism of the 6 yr oscillation is still not clear. Here, by considering the mantle and inner core angular momentum, we investigate the MICG coupling mode and its natural period (T0). Given that the strength of gravitational core-mantle coupling (Γ bar) within a recently constrained range is quite weaker than that estimated previously, the mechanism of the 6 yr oscillation still can be attributed to MICG coupling mode (i.e., T0 equals to 6 yrs), but, we require the inertia moment of fluid within the tangent cylinder involved in the 6 yr oscillation to be smaller than 1.23 ×1035 kgm2. This interpretation can be used to constrain the electromagnetic (EM) coupling at the inner core boundary (ICB). In order to study quantitatively the constraints on the EM coupling at the core-mantle boundary (CMB) from the observed 6 yr oscillation with a quality factor Q (∼51.6), we further develop the mathematical expression between the Q value based on the observations and EM coupling at the CMB. According to the Γ bar value from recent estimates and assuming that the 6 yr oscillation is in a free decay, we can obtain the radial magnetic field at the CMB is 0.52 mT∼0.62 mT when conductance at the CMB is 108 S.

  6. Effect of microstructure on the coupled electromagnetic-thermo-mechanical response of cyclotrimethylenetrinitramine-estane energetic aggregates to infrared laser radiation

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Judith A.; Zikry, M. A., E-mail: zikry@ncsu.edu [Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, North Carolina 27695-7910 (United States)

    2015-09-28

    The coupled electromagnetic (EM)-thermo-mechanical response of cyclotrimethylenetrinitramine-estane energetic aggregates under laser irradiation and high strain rate loads has been investigated for various aggregate sizes and binder volume fractions. The cyclotrimethylenetrinitramine (RDX) crystals are modeled with a dislocation density-based crystalline plasticity formulation and the estane binder is modeled with finite viscoelasticity through a nonlinear finite element approach that couples EM wave propagation with laser heat absorption, thermal conduction, and inelastic deformation. Material property and local behavior mismatch at the crystal-binder interfaces resulted in geometric scattering of the EM wave, electric field and laser heating localization, high stress gradients, dislocation density, and crystalline shear slip accumulation. Viscous sliding in the binder was another energy dissipation mechanism that reduced stresses in aggregates with thicker binder ligaments and larger binder volume fractions. This investigation indicates the complex interactions between EM waves and mechanical behavior, for accurate predictions of laser irradiation of heterogeneous materials.

  7. PID controller tuning using metaheuristic optimization algorithms for benchmark problems

    Science.gov (United States)

    Gholap, Vishal; Naik Dessai, Chaitali; Bagyaveereswaran, V.

    2017-11-01

    This paper contributes to find the optimal PID controller parameters using particle swarm optimization (PSO), Genetic Algorithm (GA) and Simulated Annealing (SA) algorithm. The algorithms were developed through simulation of chemical process and electrical system and the PID controller is tuned. Here, two different fitness functions such as Integral Time Absolute Error and Time domain Specifications were chosen and applied on PSO, GA and SA while tuning the controller. The proposed Algorithms are implemented on two benchmark problems of coupled tank system and DC motor. Finally, comparative study has been done with different algorithms based on best cost, number of iterations and different objective functions. The closed loop process response for each set of tuned parameters is plotted for each system with each fitness function.

  8. Tuning quantum correlations with intracavity photonic crystals

    Energy Technology Data Exchange (ETDEWEB)

    Castro, Maria M. de; Gomila, Damia; Zambrini, Roberta [IFISC, Institute for Cross-Disciplinary Physics and Complex Systems (CSIC-UIB), Campus UIB, E-07122 Palma de Mallorca (Spain); Garcia-March, Miguel Angel [Department of Physics, Colorado School of Mines, Golden, Colorado 80401 (United States)

    2011-09-15

    We show how to tune quantum noise in nonlinear systems by means of periodic spatial modulation. We prove that the introduction of an intracavity photonic crystal in a multimode optical parametric oscillator inhibits and enhances light quantum fluctuations. Furthermore, it leads to a significant noise reduction in field quadratures, robustness of squeezing in a wider angular range, and spatial entanglement. These results have potential benefits for quantum imaging, metrology, and quantum information applications and suggest a control mechanism of fluctuations by spatial modulation of interest also in other nonlinear systems.

  9. Tuning emergent magnetism in a Hund's impurity.

    Science.gov (United States)

    Khajetoorians, A A; Valentyuk, M; Steinbrecher, M; Schlenk, T; Shick, A; Kolorenc, J; Lichtenstein, A I; Wehling, T O; Wiesendanger, R; Wiebe, J

    2015-11-01

    The recently proposed concept of a Hund's metal--a metal in which electron correlations are driven by Hund's rule coupling-can be used to explain the exotic magnetic and electronic behaviour of strongly correlated electron systems of multi-orbital metallic materials. Tuning the abundance of parameters that determine these materials is, however, experimentally challenging. Here, we show that the basic constituent of a Hund's metal--a Hund's impurity--can be realized using a single iron atom adsorbed on a platinum surface, a system that comprises a magnetic moment in the presence of strong charge fluctuations. The magnetic properties can be controlled by using the tip of a scanning tunnelling microscope to change the binding site and degree of hydrogenation of the 3d transition-metal atom. We are able to experimentally explore a regime of four almost degenerate energy scales (Zeeman energy, temperature, Kondo temperature and magnetic anisotropy) and probe the magnetic excitations with the microscope tip. The regime of our Hund's impurity can be tuned from an emergent magnetic moment to a multi-orbital Kondo state, and the system could be used to test predictions of advanced many-body theories for non-Fermi liquids in quantum magnets or unconventional superconductors.

  10. Influences of quantum mechanically mixed electronic and vibrational pigment states in 2D electronic spectra of photosynthetic systems: Strong electronic coupling cases

    CERN Document Server

    Fujihashi, Yuta; Ishizaki, Akihito

    2015-01-01

    In 2D electronic spectroscopy studies, long-lived quantum beats have recently been observed in photosynthetic systems, and it has been suggested that the beats are produced by quantum mechanically mixed electronic and vibrational states. Concerning the electronic-vibrational quantum mixtures, the impact of protein-induced fluctuations was examined by calculating the 2D electronic spectra of a weakly coupled dimer with vibrational modes in the resonant condition [J. Chem. Phys. 142, 212403 (2015)]. This analysis demonstrated that quantum mixtures of the vibronic resonance are rather robust under the influence of the fluctuations at cryogenic temperatures, whereas the mixtures are eradicated by the fluctuations at physiological temperatures. However, this conclusion cannot be generalized because the magnitude of the coupling inducing the quantum mixtures is proportional to the inter-pigment coupling. In this study, we explore the impact of the fluctuations on electronic-vibrational quantum mixtures in a strongl...

  11. Chemical and biological sensing using tuning forks

    Science.gov (United States)

    Tao, Nongjian; Boussaad, Salah

    2012-07-10

    A device for sensing a chemical analyte is disclosed. The device is comprised of a vibrating structure having first and second surfaces and having an associated resonant frequency and a wire coupled between the first and second surfaces of the vibrating structure, wherein the analyte interacts with the wire and causes a change in the resonant frequency of the vibrating structure. The vibrating structure can include a tuning fork. The vibrating structure can be comprised of quartz. The wire can be comprised of polymer. A plurality of vibrating structures are arranged in an array to increase confidence by promoting a redundancy of measurement or to detect a plurality of chemical analytes. A method of making a device for sensing a chemical analyte is also disclosed.

  12. Post-implant evaluation of the anastomotic mechanical and geometrical coupling between human native arteries and arterial cryografts implanted in lower-limb: mechanical, histological and ultraestructural studies of implanted cryografts.

    Science.gov (United States)

    Bia, Daniel; Zócalo, Yanina; Armentano, Ricardo L; Pérez-Cámpos, Héctor; Fernández-Pin, Juan; Panuncio, Ana; Saldías, María; Mariño, Ana; Alvarez, Inés

    2012-02-01

    There is an urgent need of vascular substitutes (VS) to be used in lower limb revascularization procedures when autologous veins are not available and synthetic prosthesis are contraindicated. Since the mechanical differences with respect to native vessels are determinants of the VS failure, the substitutes should have mechanical properties similar to those of the recipient vessels. The use of cryopreserved arteries (cryografts) could overcome limitations of available VS. These work aims were to characterize (a) native vessels/implanted cryografts mechanical and geometrical coupling, (b) cryografts capability to ensure mismatch levels lesser than those expected for expanded polytetrafluoroethylene (ePTFE), (c) cryografts functional properties considering their histological and ultra-structural characteristics. Instantaneous pressure (mechano-transducers) and diameter (B-mode echography) were obtained in implanted femoro-popliteal, ileo-femoro-popliteal and axilo-humeral cryografts (n=8), in femoral arteries from recipients (n=8), recipient-like (n=15) and multiorgan donors-like (n=15) subjects, and in ePTFE segments (n=10). Calculus: (a) Mechanical parameters: elastic modulus, arterial compliance, distensibility and characteristic impedance; (b) Arterial remodeling: diameter, wall thickness, cross-sectional area and wall-to-lumen ratio; (c) Native vessels/VS coupling. Histological and structural analysis were done in explanted femoro-popliteal and axilo-humeral cryografts (n=7). Post-implant the cryografts remodeled. Their stiffness increased and the conduit function diminished. Remodeling resulted in an improvement in native vessels/cryograft coupling, which was always better than native vessels/ePTFE coupling. Post-implant cryograft remodeling improved native vessels/cryografts coupling. Cryografts would have mechanical and geometrical advantages over ePTFE. Anastomotic cryograft remodeling differed from that expected only due to haemodynamic factors. The

  13. Mechanism for the Coupled Photochemistry of Ammonia and Acetylene: Implications for Giant Planets, Comets and Interstellar Organic Synthesis

    Science.gov (United States)

    Keane, Thomas C.

    2017-09-01

    Laboratory studies provide a fundamental understanding of photochemical processes in planetary atmospheres. Photochemical reactions taking place on giant planets like Jupiter and possibly comets and the interstellar medium are the subject of this research. Reaction pathways are proposed for the coupled photochemistry of NH3 (ammonia) and C2H2 (acetylene) within the context Jupiter's atmosphere. We then extend the discussion to the Great Red Spot, Extra-Solar Giant Planets, Comets and Interstellar Organic Synthesis. Reaction rates in the form of quantum yields were measured for the decomposition of reactants and the formation of products and stable intermediates: HCN (hydrogen cyanide), CH3CN (acetonitrile), CH3CH = N-N = CHCH3 (acetaldazine), CH3CH = N-NH2 (acetaldehyde hydrazone), C2H5NH2 (ethylamine), CH3NH2 (methylamine) and C2H4 (ethene) in the photolysis of NH3/C2H2 mixtures. Some of these compounds, formed in our investigation of pathways for HCN synthesis, were not encountered previously in observational, theoretical or laboratory photochemical studies. The quantum yields obtained allowed for the formulation of a reaction mechanism that attempts to explain the observed results under varying experimental conditions. In general, the results of this work are consistent with the initial observations of Ferris and Ishikawa (1988). However, their proposed reaction pathway which centers on the photolysis of CH3CH = N-N = CHCH3 does not explain all of the results obtained in this study. The formation of CH3CH = N-N = CHCH3 by a radical combination reaction of CH3CH = N• was shown in this work to be inconsistent with other experiments where the CH3CH = N• radical is thought to form but where no CH3CH = N-N = CHCH3 was detected. The importance of the role of H atom abstraction reactions was demonstrated and an alternative pathway for CH3CH = N-N = CHCH3 formation involving nucleophilic reaction between N2H4 and CH3CH = NH is advanced.

  14. Modeling of fluid injection and withdrawal induced fault activation using discrete element based hydro-mechanical and dynamic coupled simulator

    Science.gov (United States)

    Yoon, Jeoung Seok; Zang, Arno; Zimmermann, Günter; Stephansson, Ove

    2016-04-01

    Operation of fluid injection into and withdrawal from the subsurface for various purposes has been known to induce earthquakes. Such operations include hydraulic fracturing for shale gas extraction, hydraulic stimulation for Enhanced Geothermal System development and waste water disposal. Among these, several damaging earthquakes have been reported in the USA in particular in the areas of high-rate massive amount of wastewater injection [1] mostly with natural fault systems. Oil and gas production have been known to induce earthquake where pore fluid pressure decreases in some cases by several tens of Mega Pascal. One recent seismic event occurred in November 2013 near Azle, Texas where a series of earthquakes began along a mapped ancient fault system [2]. It was studied that a combination of brine production and waste water injection near the fault generated subsurface pressures sufficient to induced earthquakes on near-critically stressed faults. This numerical study aims at investigating the occurrence mechanisms of such earthquakes induced by fluid injection [3] and withdrawal by using hydro-geomechanical coupled dynamic simulator (Itasca's Particle Flow Code 2D). Generic models are setup to investigate the sensitivity of several parameters which include fault orientation, frictional properties, distance from the injection well to the fault, amount of fluid withdrawal around the injection well, to the response of the fault systems and the activation magnitude. Fault slip movement over time in relation to the diffusion of pore pressure is analyzed in detail. Moreover, correlations between the spatial distribution of pore pressure change and the locations of induced seismic events and fault slip rate are investigated. References [1] Keranen KM, Weingarten M, Albers GA, Bekins BA, Ge S, 2014. Sharp increase in central Oklahoma seismicity since 2008 induced by massive wastewater injection, Science 345, 448, DOI: 10.1126/science.1255802. [2] Hornbach MJ, DeShon HR

  15. Mechanism for the Coupled Photochemistry of Ammonia and Acetylene: Implications for Giant Planets, Comets and Interstellar Organic Synthesis.

    Science.gov (United States)

    Keane, Thomas C

    2017-09-01

    Laboratory studies provide a fundamental understanding of photochemical processes in planetary atmospheres. Photochemical reactions taking place on giant planets like Jupiter and possibly comets and the interstellar medium are the subject of this research. Reaction pathways are proposed for the coupled photochemistry of NH3 (ammonia) and C2H2 (acetylene) within the context Jupiter's atmosphere. We then extend the discussion to the Great Red Spot, Extra-Solar Giant Planets, Comets and Interstellar Organic Synthesis. Reaction rates in the form of quantum yields were measured for the decomposition of reactants and the formation of products and stable intermediates: HCN (hydrogen cyanide), CH3CN (acetonitrile), CH3CH = N-N = CHCH3 (acetaldazine), CH3CH = N-NH2 (acetaldehyde hydrazone), C2H5NH2 (ethylamine), CH3NH2 (methylamine) and C2H4 (ethene) in the photolysis of NH3/C2H2 mixtures. Some of these compounds, formed in our investigation of pathways for HCN synthesis, were not encountered previously in observational, theoretical or laboratory photochemical studies. The quantum yields obtained allowed for the formulation of a reaction mechanism that attempts to explain the observed results under varying experimental conditions. In general, the results of this work are consistent with the initial observations of Ferris and Ishikawa (1988). However, their proposed reaction pathway which centers on the photolysis of CH3CH = N-N = CHCH3 does not explain all of the results obtained in this study. The formation of CH3CH = N-N = CHCH3 by a radical combination reaction of CH3CH = N• was shown in this work to be inconsistent with other experiments where the CH3CH = N• radical is thought to form but where no CH3CH = N-N = CHCH3 was detected. The importance of the role of H atom abstraction reactions was demonstrated and an alternative pathway for CH3CH = N-N = CHCH3 formation involving nucleophilic reaction between N2H4 and CH3CH = NH is advanced.

  16. Apparatuses and methods for tuning center frequencies

    Energy Technology Data Exchange (ETDEWEB)

    Wojciechowski, Kenneth; Olsson, Roy H.

    2016-02-23

    Apparatuses and methods for tuning center frequencies are described herein. Examples of tuning described herein including tuning using feedback from the resonator. Variable gain feedback for tuning of acoustic wave resonators is provided in some examples. An example apparatus may include a resonator and a feedback loop. The resonator may be configured to receive a tuning signal and to provide a feedback signal. The feedback signal may be based on the tuning signal. The feedback loop may be configured to receive the feedback signal from the resonator. The feedback loop further may be configured to provide the tuning signal to actively tune a center frequency of the resonator. The tuning signal may be based on the feedback signal.

  17. Neuromechanical tuning of nonlinear postural control dynamics

    Science.gov (United States)

    Ting, Lena H.; van Antwerp, Keith W.; Scrivens, Jevin E.; McKay, J. Lucas; Welch, Torrence D. J.; Bingham, Jeffrey T.; DeWeerth, Stephen P.

    2009-06-01

    Postural control may be an ideal physiological motor task for elucidating general questions about the organization, diversity, flexibility, and variability of biological motor behaviors using nonlinear dynamical analysis techniques. Rather than presenting "problems" to the nervous system, the redundancy of biological systems and variability in their behaviors may actually be exploited to allow for the flexible achievement of multiple and concurrent task-level goals associated with movement. Such variability may reflect the constant "tuning" of neuromechanical elements and their interactions for movement control. The problem faced by researchers is that there is no one-to-one mapping between the task goal and the coordination of the underlying elements. We review recent and ongoing research in postural control with the goal of identifying common mechanisms underlying variability in postural control, coordination of multiple postural strategies, and transitions between them. We present a delayed-feedback model used to characterize the variability observed in muscle coordination patterns during postural responses to perturbation. We emphasize the significance of delays in physiological postural systems, requiring the modulation and coordination of both the instantaneous, "passive" response to perturbations as well as the delayed, "active" responses to perturbations. The challenge for future research lies in understanding the mechanisms and principles underlying neuromechanical tuning of and transitions between the diversity of postural behaviors. Here we describe some of our recent and ongoing studies aimed at understanding variability in postural control using physical robotic systems, human experiments, dimensional analysis, and computational models that could be enhanced from a nonlinear dynamics approach.

  18. Tuning History in Latin America

    Science.gov (United States)

    Velázquez Albo, Marco

    2017-01-01

    This article analyses the development and achievements of the area of History in the Tuning-Latin America Project from its launch in 2004 to its completion in 2013. Through two phases and nine general meetings, academics from Argentina, Brazil, Chile, Colombia, Costa Rica, Cuba, Guatemala, Mexico and Peru, along with academics from Spain, Portugal…

  19. Dynamical coupled modes theory for an s{sub ±}-pairing mechanism of superconductivity in doped iron pnictides

    Energy Technology Data Exchange (ETDEWEB)

    Kiselev, Mikhail [International Center for Theoretical Physics, I-34151 Trieste (Italy); Efremov, Dmitriy; Drechsler, Stefan-Ludwig; Brink, Jeroen van den [Institute for Theoretical Solid State Physics at the Leibniz Institute for Solid State an Materials Research Dresden, IFW-Dresden, D-01171 Dresden (Germany); Kikoin, Konstantin [School of Physics and Astronomy, Tel Aviv University, 69978 Tel Aviv (Israel)

    2016-07-01

    We develop a high-temperature approach to the problem of the interplay between magnetic and superconducting phases in multi-band iron pnictides. A dynamical mode-mode coupling theory is derived from the the microscopic theory based on the solution of the coupled Bethe-Salpeter equations. We focus on the vicinity to a spin density wave (SDW) where spin fluctuations enhance the onset of superconducting ordering. Special attention is paid to arsenic deficient materials where As vacancies behaves as effective magnetic defects. The proposed theory allows generalization to multi-mode regimes.

  20. Numerical research on the neutronic/thermal-hydraulic/mechanical coupling characteristics of the optimized helium cooled solid breeder blanket for CFETR

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Shijie; Zhang, Dalin, E-mail: dlzhang@mail.xjtu.edu.cn; Cheng, Jie; Tian, Wenxi; Su, G.H.

    2017-01-15

    As one of the candidate tritium breeding blankets for Chinese Fusion Engineering Test Reactor (CFETR), a conceptual structure of the helium cooled solid breeder blanket has recently been proposed. The neutronic, thermal-hydraulic and mechanical characteristics of the blanket directly affect its tritium breeding and safety performance. Therefore, neutronic/thermal-hydraulic/mechanical coupling analyses are of vital importance for a reliable blanket design. In this work, first, three-dimensional neutronics analysis and optimization of the typical outboard equatorial blanket module (No. 12) were performed for the comprehensive optimal scheme. Then, thermal and fluid dynamic analyses of the scheme under both normal and critical conditions were performed and coupled with the previous neutronic calculation results. With thermal-hydraulic boundaries, thermo-mechanical analyses of the structure materials under normal, critical and blanket over-pressurization conditions were carried out. In addition, several parametric sensitivity studies were also conducted to investigate the influences of the main parameters on the blanket temperature distributions. In this paper, the coupled analyses verify the reasonability of the optimized conceptual design preliminarily and can provide an important reference for the further analysis and optimization design of the CFETR helium cooled solid breeder blanket.

  1. Coupled thermal-hydrological-mechanical analyses of the YuccaMountain Drift Scale Test - Comparison of field measurements topredictions of four different numerical models

    Energy Technology Data Exchange (ETDEWEB)

    Rutqvist, J.; Barr, D.; Datta, R.; Gens, A.; Millard, A.; Olivella, S.; Tsang, C.-F.; Tsang, Y.

    2004-08-30

    The Yucca Mountain Drift Scale Test (DST) is a multiyear, large-scale underground heater test designed to study coupled thermal-hydrological-mechanical-chemical behavior in unsaturated fractured and welded tuff. As part of the international cooperative code-comparison project DECOVALEX, four research teams used four different numerical models to simulate and predict coupled thermal-hydrological-mechanical (THM) processes at the DST. The simulated processes included above-boiling temperature changes, liquid and vapor water movements, rock-mass stress and displacement, and THM-induced changes in fracture permeability. Model predictions were evaluated by comparison to measurements of temperature, water saturation,displacement, and air permeability. The generally good agreement between simulated and measured THM data shows that adopted continuum model approaches are adequate for simulating relevant coupled THM processes at the DST. Moreover, TM-induced rock-mass deformations were reasonably well predicted using elastic models, although some individual displacements appeared to be better captured using an elasto-plastic model. It is concluded that fracture closure/opening caused by change in normal stress across fractures is the dominant mechanism for TM-induced changes in intrinsic fracture permeability at the DST, whereas fracture shear dilation appears to be less significant. This indicates that TM-induced changes in intrinsic permeability at the DST, which are within one order of magnitude, tend to be reversible.

  2. Non-parametric Tuning of PID Controllers A Modified Relay-Feedback-Test Approach

    CERN Document Server

    Boiko, Igor

    2013-01-01

    The relay feedback test (RFT) has become a popular and efficient  tool used in process identification and automatic controller tuning. Non-parametric Tuning of PID Controllers couples new modifications of classical RFT with application-specific optimal tuning rules to form a non-parametric method of test-and-tuning. Test and tuning are coordinated through a set of common parameters so that a PID controller can obtain the desired gain or phase margins in a system exactly, even with unknown process dynamics. The concept of process-specific optimal tuning rules in the nonparametric setup, with corresponding tuning rules for flow, level pressure, and temperature control loops is presented in the text.   Common problems of tuning accuracy based on parametric and non-parametric approaches are addressed. In addition, the text treats the parametric approach to tuning based on the modified RFT approach and the exact model of oscillations in the system under test using the locus of a perturbedrelay system (LPRS) meth...

  3. A New Hybrid Gyroscope with Electrostatic Negative Stiffness Tuning

    Directory of Open Access Journals (Sweden)

    Xian Chu

    2013-05-01

    Full Text Available A variety of gyroscopes have been extensively studied due to their capability of precision detection of rotation rates and extensive applications in navigation, guidance and motion control. In this work, a new Hybrid Gyroscope (HG which combines the traditional Dynamically Tuned Gyroscope (DTG with silicon micromachined technology is investigated. The HG not only has the potentiality of achieving the same high precision as the traditional DTG, but also features a small size and low cost. The theoretical mechanism of the HG with a capacitance transducer and an electrostatic torquer is derived and the influence of the installation errors from the capacitance plate and the disc rotor module is investigated. A new tuning mechanism based on negative stiffness rather than the traditional dynamic tuning is proposed. The experimental results prove that the negative stiffness tuning is practicable and a tuning voltage of as high as 63 V is demonstrated. Due to the decreased installation error, the non-linearity of the scale factor is reduced significantly from 11.78% to 0.64%, as well as the asymmetry from 93.3% to 1.56% in the open loop condition. The rebalancing close-loop control is simulated and achieved experimentally, which proves that the fundamental principle of the HG is feasible.

  4. A new hybrid gyroscope with electrostatic negative stiffness tuning.

    Science.gov (United States)

    Yang, Bo; Guan, Yumei; Wang, Shourong; Zou, Qi; Chu, Xian; Xue, Haiyan

    2013-05-30

    A variety of gyroscopes have been extensively studied due to their capability of precision detection of rotation rates and extensive applications in navigation, guidance and motion control. In this work, a new Hybrid Gyroscope (HG) which combines the traditional Dynamically Tuned Gyroscope (DTG) with silicon micromachined technology is investigated. The HG not only has the potentiality of achieving the same high precision as the traditional DTG, but also features a small size and low cost. The theoretical mechanism of the HG with a capacitance transducer and an electrostatic torquer is derived and the influence of the installation errors from the capacitance plate and the disc rotor module is investigated. A new tuning mechanism based on negative stiffness rather than the traditional dynamic tuning is proposed. The experimental results prove that the negative stiffness tuning is practicable and a tuning voltage of as high as 63 V is demonstrated. Due to the decreased installation error, the non-linearity of the scale factor is reduced significantly from 11.78% to 0.64%, as well as the asymmetry from 93.3% to 1.56% in the open loop condition. The rebalancing close-loop control is simulated and achieved experimentally, which proves that the fundamental principle of the HG is feasible.

  5. Research on Effective Electric-Mechanical Coupling Coefficient of Sandwich Type Piezoelectric Ultrasonic Transducer Using Bending Vibration Mode

    Directory of Open Access Journals (Sweden)

    Qiang Zhang

    2015-01-01

    Full Text Available An analytical model on electromechanical coupling coefficient and the length optimization of a bending piezoelectric ultrasonic transducer are proposed. The piezoelectric transducer consists of 8 PZT elements sandwiched between four thin electrodes, and the PZT elements are clamped by a screwed connection between fore beam and back beam. Firstly, bending vibration model of the piezoelectric transducer is built based on the Timoshenko beam theory. Secondly, the analytical model of effective electromechanical coupling coefficient is built based on the bending vibration model. Energy method and electromechanical equivalent circuit method are involved in the modelling process. To validate the analytical model, sandwich type piezoelectric transducer example in second order bending vibration mode is analysed. Effective electromechanical coupling coefficient of the transducer is optimized with simplex reflection technique, and the optimized ratio of length of the transducers is obtained. Finally, experimental prototypes of the sandwich type piezoelectric transducers are fabricated. Bending vibration mode and impedance of the experimental prototypes are tested, and electromechanical coupling coefficient is obtained according to the testing results. Results show that the analytical model is in good agreement with the experimental model.

  6. Electromagnetic and mechanical characterisation of ITER CS-MC conductors affected by transverse cyclic loading, part 1: coupling current loss

    NARCIS (Netherlands)

    Nijhuis, Arend; Noordman, Niels H.W.; ten Kate, Herman H.J.; Mitchell, Neil; Bruzzone, Pierluigi

    1999-01-01

    The magnetic field generated by a coil acts on the cable which results in a transverse force on the strands. This affects the interstrand contact resistances (Rc), the coupling current loss and current redistribution during field changes. A special cryogenic press has been built to study the

  7. Analysis and modeling of coupled thermo-hydro-mechanical phenomena in 3D fractured media; Analyse et modelisation des phenomenes couples thermo-hydromecaniques en milieux fractures 3D

    Energy Technology Data Exchange (ETDEWEB)

    Canamon Valera, I

    2006-11-15

    This doctoral research was conducted as part of a joint France-Spain co-tutelage PhD thesis in the framework of a bilateral agreement between two universities, the Institut National Polytechnique de Toulouse (INPT) and the Universidad Politecnica de Madrid (UPM). It concerns a problem of common interest at the national and international levels, namely, the disposal of radioactive waste in deep geological repositories. The present work is devoted, more precisely, to near-field hydrogeological aspects involving mass and heat transport phenomena. The first part of the work is devoted to a specific data interpretation problem (pressures, relative humidities, temperatures) in a multi-barrier experimental system at the scale of a few meters - the 'Mock-Up Test' of the FEBEX project, conducted in Spain. Over 500 time series are characterized in terms of spatial, temporal, and/or frequency/scale-based statistical analysis techniques. The time evolution and coupling of physical phenomena during the experiment are analyzed, and conclusions are drawn concerning the behavior and reliability of the sensors. The second part of the thesis develops in more detail the 3-Dimensional (3D) modeling of coupled Thermo-Hydro-Mechanical phenomena in a fractured porous rock, this time at the scale of a hundred meters, based on the data of the 'In-Situ Test' of the FEBEX project conducted at the Grimsel Test Site in the Swiss Alps. As a first step, a reconstruction of the 3D fracture network is obtained by Monte Carlo simulation, taking into account through optimization the geomorphological data collected around the FEBEX gallery. The heterogeneous distribution of traces observed on the cylindrical wall of the tunnel is fairly well reproduced in the simulated network. In a second step, we develop a method to estimate the equivalent permeability of a many-fractured block by extending the superposition method of Ababou et al. [1994] to the case where the permeability of

  8. Data Driven Tuning of Inventory Controllers

    DEFF Research Database (Denmark)

    Huusom, Jakob Kjøbsted; Santacoloma, Paloma Andrade; Poulsen, Niels Kjølstad

    2007-01-01

    A systematic method for criterion based tuning of inventory controllers based on data-driven iterative feedback tuning is presented. This tuning method circumvent problems with modeling bias. The process model used for the design of the inventory control is utilized in the tuning...... as an approximation to reduce time required on experiments. The method is illustrated in an application with a multivariable inventory control implementation on a four tank system....

  9. Collecting EUV mask images through focus by wavelength tuning

    Energy Technology Data Exchange (ETDEWEB)

    Goldberg, Kenneth A.; Mochi, Iacopo; Huh, Sungmin

    2009-02-23

    Using an extreme-ultraviolet (EUV) microscope to produce high-quality images of EUV reticles, we have developed a new wavelength tuning method to acquire through-focus data series with a higher level of stability and repeatability than was previously possible. We utilize the chromatic focal-length dependence of a diffractive Fresnel zoneplate objective lens, and while holding the mask sample mechanically still, we tune the wavelength through a narrow range, in small steps. In this paper, we demonstrate the method and discuss the relative advantages that this data collection technique affords.

  10. Tuning Properties in Silver Clusters

    KAUST Repository

    Joshi, Chakra Prasad

    2015-07-09

    The properties of Ag nanoclusters are not as well understood as those of their more precious Au cousins. However, a recent surge in the exploration of strategies to tune the physicochemical characteristics of Ag clusters addresses this imbalance, leading to new insights into their optical, luminescence, crystal habit, metal-core, ligand-shell and environmental properties. In this Perspective, we provide an overview of the latest strategies along with a brief introduction of the theoretical framework necessary to understand the properties of silver nanoclusters and the basis for their tuning. The advances in cluster research and the future prospects presented in this Perspective will eventually guide the next large systematic study of nanoclusters, resulting in a single collection of data similar to the periodic table of elements.

  11. Distributed Tuning of Boundary Resources

    DEFF Research Database (Denmark)

    Eaton, Ben; Elaluf-Calderwood, Silvia; Sørensen, Carsten

    2015-01-01

    in the context of a paradoxical tension between the logic of generative and democratic innovations and the logic of infrastructural control. Boundary resources play a critical role in managing the tension as a firm that owns the infrastructure can secure its control over the service system while independent...... firms can participate in the service system. In this study, we explore the evolution of boundary resources. Drawing on Pickering’s (1993) and Barrett et al.’s (2012) conceptualizations of tuning, the paper seeks to forward our understanding of how heterogeneous actors engage in the tuning of boundary...... resources within Apple’s iOS service system. We conduct an embedded case study of Apple’s iOS service system with an in-depth analysis of 4,664 blog articles concerned with 30 boundary resources covering 6 distinct themes. Our analysis reveals that boundary resources of service systems enabled by digital...

  12. Tuned mass absorber on a flexible structure

    DEFF Research Database (Denmark)

    Krenk, Steen; Høgsberg, Jan Becker

    2014-01-01

    The classic design of a tuned mass absorber is based on a simple two-mass analogy in which the tuned mass is connected to the structural mass with a spring and a viscous damper. In a flexible multi-degree-of-freedom structure the tuned mass absorber is typically introduced to provide damping of a...

  13. Electrical tuning of a quantum plasmonic resonance

    Science.gov (United States)

    Liu, Xiaoge; Kang, Ju-Hyung; Yuan, Hongtao; Park, Junghyun; Kim, Soo Jin; Cui, Yi; Hwang, Harold Y.; Brongersma, Mark L.

    2017-09-01

    Surface plasmon (SP) excitations in metals facilitate confinement of light into deep-subwavelength volumes and can induce strong light-matter interaction. Generally, the SP resonances supported by noble metal nanostructures are explained well by classical models, at least until the nanostructure size is decreased to a few nanometres, approaching the Fermi wavelength λF of the electrons. Although there is a long history of reports on quantum size effects in the plasmonic response of nanometre-sized metal particles, systematic experimental studies have been hindered by inhomogeneous broadening in ensemble measurements, as well as imperfect control over size, shape, faceting, surface reconstructions, contamination, charging effects and surface roughness in single-particle measurements. In particular, observation of the quantum size effect in metallic films and its tuning with thickness has been challenging as they only confine carriers in one direction. Here, we show active tuning of quantum size effects in SP resonances supported by a 20-nm-thick metallic film of indium tin oxide (ITO), a plasmonic material serving as a low-carrier-density Drude metal. An ionic liquid (IL) is used to electrically gate and partially deplete the ITO layer. The experiment shows a controllable and reversible blue-shift in the SP resonance above a critical voltage. A quantum-mechanical model including the quantum size effect reproduces the experimental results, whereas a classical model only predicts a red shift.

  14. High-frequency tuning of high-powered DFB MOPA system with diffraction limited power up to 1.5W

    Science.gov (United States)

    Sacher, Joachim; Knispel, Richard; Stry, Sandra

    2006-02-01

    The combination of high power, small linewidth and fast tunability is essential for many fields in high resolution spectroscopy. External cavity laser diode systems are limited in tuning speed to several kHz by the resonance frequency of the mechanical assembly together with the actuator. We report on the application of a directly modulated DFB laser as master laser within a master laser power amplifier (MOPA) configuration. This DFB MOPA system combines fast frequency tuning up to more then 100kHz tuning speed, a tuning amplitude of more than 10GHz, a narrow linewidth below 5MHz with high output power of 1500mW and an almost Gaussian shaped beam quality (M2<1.2). The coupling efficiency to optical waveguides as well as single mode fibers exceeds 60%. This concept can be realized within the wavelength regime between 730 and 1060nm. We approved this light source for high resolution spectroscopy by frequency locking to the saturated Rubidium absorption at 780nm. Applying two DFB lasers as master lasers of the MOPA configuration opens the choice to high frequency modulated THz radiation.

  15. Hydro mechanical coupling for non linear behaviour laws. Application to petroleum problems; Couplage hydromecanique pour des lois de comportement non lineaires Application a des problemes petroliers

    Energy Technology Data Exchange (ETDEWEB)

    Longuemare, P.

    1996-11-28

    The aim of this study is to provide a better description of the rock contribution to fluid flows in sedimentary basins and petroleum reservoirs. After a study of the mechanical behaviour of high porosity chalks and shales, we present the elaboration of an elastoplastic constitutive model for the description of their behaviour under various strain and stress paths. This model is introduced in a coupled poro-mechanical approach and used to study the advantages of a good description of strain and stress paths in petroleum reservoirs and sedimentary basins studies. Hydro-mechanical modelling of the behaviour of petroleum reservoir allowed us to analyse the influence of boundary limit conditions on stress paths recovery rates. The study of sedimentary basins showed the importance of the consideration of the evolution of the porosity with time due to the time-scale difference between the laboratory and the field data. (author) 58 refs.

  16. Predictive Modeling of Polymer Mechanical Behavior Coupled to Chemical Change/ Technique Development for Measuring Polymer Physical Aging.

    Energy Technology Data Exchange (ETDEWEB)

    Kropka, Jamie Michael [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Stavig, Mark E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Arechederra, Gabe Kenneth [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); McCoy, John D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-09-01

    Develop an understanding of the evolution of glassy polymer mechanical response during aging and the mechanisms associated with that evolution. That understanding will be used to develop constitutive models to assess the impact of stress evolution in encapsulants on NW designs.

  17. Non covalent interactions in RNA and DNA base pairs: a quantum-mechanical study of the coupling between solvent and electronic density.

    Science.gov (United States)

    Lipparini, Filippo; Scalmani, Giovanni; Mennucci, Benedetta

    2009-12-28

    It is well-known that a solvent can modify the relative importance of the different constituents (electrostatic and dispersion) of non-covalent interactions, but much less is known about how these solvent-induced modifications specifically couple with the polarization of the electronic density and electronic correlation. Here we present a quantum mechanical analysis of the effects of the solvent on the non covalent interactions (both stacking and hydrogen bonding) in base pairs using a hierarchy of combinations between a MP2 correlated description for the base pairs and the polarizable continuum model (PCM) for the solvent. A comparison of the results obtained in these different combinations of increasing accuracy allows us to better analyze the important role played by the coupling between correlated electronic densities and solvent polarization in determining the relative importance of stacking and hydrogen bonding effects.

  18. Fluid-Thermal-Structural Coupled Analysis of a Radial Inflow Micro Gas Turbine Using Computational Fluid Dynamics and Computational Solid Mechanics

    Directory of Open Access Journals (Sweden)

    Yonghui Xie

    2014-01-01

    Full Text Available A three-dimensional fluid-thermal-structural coupled analysis for a radial inflow micro gas turbine is conducted. First, a fluid-thermal coupled analysis of the flow and temperature fields of the nozzle passage and the blade passage is performed by using computational fluid dynamics (CFD. The flow and heat transfer characteristics of different sections are analyzed in detail. The thermal load and the aerodynamic load are then obtained from the temperature field and the pressure distribution. The stress distributions of the blade are finally studied by using computational solid mechanics (CSM considering three cases of loads: thermal load, aerodynamics load combined with centrifugal load, and all the three types of loads. The detailed parameters of the flow, temperature, and the stress are obtained and analyzed. The numerical results obtained provide a useful knowledge base for further exploration of radial gas turbine design.

  19. Iterative Feedback Tuning in district heating systems; Iterative Feedback Tuning i vaermeproduktionsanlaeggningar

    Energy Technology Data Exchange (ETDEWEB)

    Raaberg, Martin; Velut, Stephane; Bari, Siavosh Amanat

    2010-10-15

    The project goal is to evaluate and describe how Iterative Feedback Tuning (IFT) can be used to tune controllers in the typical control loops in heat- and power plants. There are only a few practical studies carried out for IFT and they are not really relevant for power and heat processes. It is the practical problems in implementing the IFT and the result of trimming that is the focus of this project. The project will start with theoretical studies of the IFT-method, then realization and simple simulations in scilab. The IFT equations are then implemented in Freelance 2000, an ABB control system, for practical tests on a SISO- and a MIMO-process. By performing reproducible experiments on the process and analyze the results IFT can adjust the controller parameters to minimize a cost function that represents the control goal. The project selected for SISO experiments a pressure controller in an oil transportation system. By controlling the valve position of a control valve for the reversal to the supply tank, the pressure in the oil transport system is regulated. A disturbance in oil pressure can be achieved by changing the position of a valve that lets oil through to the day tank. The selected MIMO-process is a pre-heater in a degassing process. In this process, a valve on the secondary side is utilized to control the flow in the secondary system. A valve on the primary side is utilized to control the district heating water flow through the heat exchanger to control the temperature on the secondary side. An increased secondary flow increases the heat demand and thus requiring an increase in primary flow to maintain the secondary side outlet temperature. This is the cross-coupling responsible for why it is an advantage to consider the process as multi-variable. Using the IFT method, the two original PID-controllers and a feed-forward controller is tuned simultaneously. IFT-method was difficult to implement but worked well in both simulations and in real processes

  20. Predictive Performance Tuning of OpenACC Accelerated Applications

    KAUST Repository

    Siddiqui, Shahzeb

    2014-05-04

    Graphics Processing Units (GPUs) are gradually becoming mainstream in supercomputing as their capabilities to significantly accelerate a large spectrum of scientific applications have been clearly identified and proven. Moreover, with the introduction of high level programming models such as OpenACC [1] and OpenMP 4.0 [2], these devices are becoming more accessible and practical to use by a larger scientific community. However, performance optimization of OpenACC accelerated applications usually requires an in-depth knowledge of the hardware and software specifications. We suggest a prediction-based performance tuning mechanism [3] to quickly tune OpenACC parameters for a given application to dynamically adapt to the execution environment on a given system. This approach is applied to a finite difference kernel to tune the OpenACC gang and vector clauses for mapping the compute kernels into the underlying accelerator architecture. Our experiments show a significant performance improvement against the default compiler parameters and a faster tuning by an order of magnitude compared to the brute force search tuning.

  1. Distinguishing attentional gain and tuning in young and older adults.

    Science.gov (United States)

    Schmitz, Taylor W; Dixon, Matthew L; Anderson, Adam K; De Rosa, Eve

    2014-11-01

    Here we examined with functional magnetic resonance imaging (fMRI) whether advanced age affects 2 mechanisms of attention that are widely thought to enhance signal processing in the sensory neocortex: gain and tuning. Healthy young and older adults discriminated faces under varying levels of object competition while fMRI was acquired. In young adults, cortical response magnitude to attended faces was maintained despite increasing competition, consistent with gain. Cortical response selectivity, indexed from repetition suppression, also increased only for attended faces despite increasing competition, consistent with tuning. Older adults exhibited intact gain, but altered tuning, with extrastriate cortical tuning determined by object salience rather than attention. Moreover, the magnitude of this susceptibility to stimulus-driven processing was associated with a redistribution of attention-driven competitive processes to the frontal cortices. These data indicate that although both gain and tuning are modulated by increased perceptual competition, they are functionally dissociable in the extrastriate cortices, exhibit differential susceptibility to advanced aging, and spare the frontal cortices a considerable processing burden through early selection. Copyright © 2014 Elsevier Inc. All rights reserved.

  2. Tribotronic Tuning Diode for Active Analog Signal Modulation.

    Science.gov (United States)

    Zhou, Tao; Yang, Zhi Wei; Pang, Yaokun; Xu, Liang; Zhang, Chi; Wang, Zhong Lin

    2017-01-24

    Realizing active interaction with external environment/stimuli is a great challenge for current electronics. In this paper, a tribotronic tuning diode (TTD) is proposed by coupling a variable capacitance diode and a triboelectric nanogenerator in free-standing sliding mode. When the friction layer is sliding on the device surface for electrification, a reverse bias voltage is created and applied to the diode for tuning the junction capacitance. When the sliding distance increases from 0 to 25 mm, the capacitance of the TTD decreases from about 39 to 8 pF. The proposed TTD has been integrated into analog circuits and exhibited excellent performances in frequency modulation, phase shift, and filtering by sliding a finger. This work has demonstrated tunable diode and active analog signal modulation by tribotronics, which has great potential to replace ordinary variable capacitance diodes in various practical applications such as signal processing, electronic tuning circuits, precise tuning circuits, active sensor networks, electronic communications, remote controls, flexible electronics, etc.

  3. Gauge hierarchy problem in asymptotically safe gravity - The resurgence mechanism

    Science.gov (United States)

    Wetterich, Christof; Yamada, Masatoshi

    2017-07-01

    The gauge hierarchy problem could find a solution within the scenario of asymptotic safety for quantum gravity. We discuss a ;resurgence mechanism; where the running dimensionless coupling responsible for the Higgs scalar mass first decreases in the ultraviolet regime and subsequently increases in the infrared regime. A gravity induced large anomalous dimension plays a crucial role for the required ;self-tuned criticality; in the ultraviolet regime beyond the Planck scale.

  4. Oracle SQL tuning with Oracle SQLTXPLAIN

    CERN Document Server

    Charalambides, Stelios

    2013-01-01

    Oracle SQL Tuning with SQLTXPLAIN is a practical guide to SQL tuning the way Oracle's own experts do it, using a freely downloadable tool called SQLTXPLAIN. Using this simple tool you'll learn how to tune even the most complex SQL, and you'll learn to do it quickly, without the huge learning curve usually associated with tuning as a whole.  Firmly based in real world problems, this book helps you reclaim system resources and avoid the most common bottleneck in overall performance, badly tuned SQL.  You'll learn how the optimizer works, how to take advantage of its latest features, and when it'

  5. Liquid-solid phase transition of physical hydrogels subject to an externally applied electro-chemo-mechanical coupled field with mobile ionic species.

    Science.gov (United States)

    Wu, Tao; Li, Hua

    2017-08-09

    In this study, a model was multiphysically developed for the simulation of the phase transition of physical hydrogels between liquid solution and solid gel states, subject to an electro-chemo-mechanically coupled field, with the effect of the mobile ionic species in the solution. The present model consists of the governing equations for the equilibrium of forces and the conservation of mass, Maxwell's equations, and an evolution equation for the interface. Based on the second law of thermodynamics, the constitutive equations are formulated from the energy viewpoint, including a novel formulation of free energy with the effect of crosslink density. The present model may be reduced to Suo's non-equilibrium thermodynamic theory if the interface is ignored when only a single phase exists. It may also be reduced to Dolbow's model for gel-gel phase transition when the electric field is ignored. Therefore, the present model becomes more generalized since it is able to represent both the bulk phase and the interface behaviors, and the mechanical field is simultaneously coupled with both the electric and chemical fields. In the first case study, the system at equilibrium state was numerically investigated for analysis of the influences of the electrical and chemical potentials as well as the mechanical pressure externally imposed on the boundary of the system domain. The second case study presents a spherically symmetrical solution-gel phase transition at non-equilibrium states, with the emphasis on the evolution of both the interface and electrochemical potentials.

  6. Intracellular Ca2+, intercellular electrical coupling, and mechanical activity in ischemic rabbit papillary muscle. Effects of preconditioning and metabolic blockade

    NARCIS (Netherlands)

    Dekker, L. R.; Fiolet, J. W.; VanBavel, E.; Coronel, R.; Opthof, T.; Spaan, J. A.; Janse, M. J.

    1996-01-01

    During myocardial ischemia, electrical uncoupling and contracture herald irreversible damage. In the present study, we tested the hypothesis that an increase of intracellular Ca2+ is an important factor initiating these events. Therefore, we simultaneously determined tissue resistance, mechanical

  7. Angiotensin II receptor subtypes are coupled with distinct signal-transduction mechanisms in neurons and astrocytes from rat brain

    Energy Technology Data Exchange (ETDEWEB)

    Sumners, C.; Wei Tang; Zelezna, B.; Raizada, M.K. (Univ. of Florida, Gainesville (United States))

    1991-09-01

    Both neurons and astrocytes contain specific receptors for angiotensin II (AII). The authors used selective ligands for the AT{sub 1} and AT{sub 2} types of AII receptors to investigate the expression of functional receptor subtypes in astrocyte cultures and neuron cultures from 1-day-old (neonatal) rat brain. In astrocyte cultures, competition of {sup 125}I-labeled AII ({sup 125}I-AII) specific binding with AT{sub 1} (DuP753) or AT{sub 2} {l brace}PD123177, CGP42112A, (Phe(p-NH{sub 2}){sup 6})AII{r brace} selective receptor ligands revealed a potency series of AII > DuP753 > > > CGP42112A > (Phe(p-NH{sub 2}){sup 6})AII > PD123177. These results suggest a predominance of the AT{sub 1} receptor subtype in neonatal astrocytes. {sup 125}I-AII specific binding to neonate neuronal cultures was reduced 73-84% by 1 {mu} MPD123177, and the residual {sup 125}I-AII specific binding was eliminated by DuP753. The results suggest that astrocyte cultures from neonatal rat brains contain predominantly AT{sub 1} receptors that are coupled to a stimulation of inositophospholipid hydrolysis. In contrast, neuron cultures from neonatal rat brain contain mostly AT{sub 2} receptors that are coupled to a reduction in basal cGMP levels, but a smaller population of AT{sub 1} receptors is also present in these neurons.

  8. An adaptive information technology for the operative diagnostics of the tropical cyclones; solar-terrestrial coupling mechanisms

    Science.gov (United States)

    Krapivin, Vladimir F.; Soldatov, Vladimir Yu.; Varotsos, Costas A.; Cracknell, Arthur P.

    2012-11-01

    The tools of sequential analysis and percolation theory are herewith used to study the transition processes in the coupled ocean-atmosphere system. To accomplish this aim the recently proposed instability indicator for the detection of the characteristics of the state for this system, is utilized. In more detail, the case of the transition processes for Baltic Sea assessed by the Beaufort Scale is examined by investigating the efficiency of the afore-mentioned indicator.We show that the crucial parameter is not the energy source, like the solar radiation, but the energy conversion. Numerical experiments conducted herewith showed that such an indicator facilitates the monitoring of the variability and direction of transition processes in the oceans, and is capable to predict a remarkable change of the ocean-atmosphere system states. It is finally shown that the combination of sequential and cluster analysis with the percolation procedure allows for the detection of a tropical hurricane up to three days in advance of its start. The tool presented may also be applied to the development of relevant indicators for the predictions of magnetosphere-ionosphere-thermosphere coupling and the solar wind-magnetosphere interactions. Finally, future problems on the subject are discussed.

  9. Evaluation of coupled thermo-hydro-mechanical phenomena in the near field for geological disposal of high-level radioactive waste

    Energy Technology Data Exchange (ETDEWEB)

    Chijimatsu, Masakazu; Fujita, Tomoo; Sugita, Yutaka; Taniguchi, Wataru [Japan Nuclear Cycle Development Inst., Tokai Works, Waste Management and Fuel Cycle Research Center, Waste Isolation Research Division, Barrier Performance Group, Tokai, Ibaraki (Japan)

    2000-01-01

    Geological disposal of high-level radioactive waste (HLW) in Japan is based on a multibarrier system composed of engineered and natural barriers. The engineered barriers are composed of vitrified waste confined within a canister, overpack and buffer material. Highly compacted bentonite clay is considered one of the most promising candidate buffer material mainly because of its low hydraulic conductivity and high adsorption capacity of radionuclides. In a repository of HLW, complex thermal, hydraulic and mechanical (T-H-M) phenomena will take place, involving the interactive processes between radioactive decay heat from the vitrified waste, infiltration of ground water and stress generation due to the earth pressure, the thermal loading and the swelling pressure of the buffer material. In order to evaluate the performance of the buffer material, the coupled T-H-M behaviors within the compacted bentonite have to be modelled. Before establishing a fully coupled T-H-M model, the mechanism of each single phenomenon or partially coupled phenomena should be identified. Furthermore, in order to evaluate the coupled T-H-M phenomena, the analysis model was developed physically and numerically and the adequacy and the applicability was tested though the engineered scale laboratory test and in-situ test. In this report, the investigative results for the development of coupled T-H-M model were described. This report consists of eight chapters. In Chapter 1, the necessity of coupled T-H-M model in the geological disposal project of the high-level radioactive waste was described . In Chapter 2, the laboratory test results of the rock sample and the buffer material for the coupled T-H-M analysis were shown. The rock samples were obtained from the in-situ experimental site at Kamaishi mine. As the buffer material, bentonite clay (Kunigel V1 and Kunigel OT-9607) and bentonite-sand mixture were used. In Chapter 3, in-situ tests to obtain the rock property were shown. As in-situ tests

  10. New tuning method for PID controller.

    Science.gov (United States)

    Shen, Jing-Chung

    2002-10-01

    In this paper, a tuning method for proportional-integral-derivative (PID) controller and the performance assessment formulas for this method are proposed. This tuning method is based on a genetic algorithm based PID controller design method. For deriving the tuning formula, the genetic algorithm based design method is applied to design PID controllers for a variety of processes. The relationship between the controller parameters and the parameters that characterize the process dynamics are determined and the tuning formula is then derived. Using simulation studies, the rules for assessing the performance of a PID controller tuned by the proposed method are also given. This makes it possible to incorporate the capability to determine if the PID controller is well tuned or not into an autotuner. An autotuner based on this new tuning method and the corresponding performance assessment rules is also established. Simulations and real-time experimental results are given to demonstrate the effectiveness and usefulness of these formulas.

  11. Influence of dynamic coupled hydro-bio-mechanical processes on response of municipal solid waste and liner system in bioreactor landfills.

    Science.gov (United States)

    Reddy, Krishna R; Kumar, Girish; Giri, Rajiv K

    2017-05-01

    A two-dimensional (2-D) mathematical model is presented to predict the response of municipal solid waste (MSW) of conventional as well as bioreactor landfills undergoing coupled hydro-bio-mechanical processes. The newly developed and validated 2-D coupled mathematical modeling framework combines and simultaneously solves a two-phase flow model based on the unsaturated Richard's equation, a plain-strain formulation of Mohr-Coulomb mechanical model and first-order decay kinetics biodegradation model. The performance of both conventional and bioreactor landfill was investigated holistically, by evaluating the mechanical settlement, extent of waste degradation with subsequent changes in geotechnical properties, landfill slope stability, and in-plane shear behavior (shear stress-displacement) of composite liner system and final cover system. It is concluded that for the given specific conditions considered, bioreactor landfill attained an overall stabilization after a continuous leachate injection of 16years, whereas the stabilization was observed after around 50years of post-closure in conventional landfills, with a total vertical strain of 36% and 37% for bioreactor and conventional landfills, respectively. The significant changes in landfill settlement, the extent of MSW degradation, MSW geotechnical properties, along with their influence on the in-plane shear response of composite liner and final cover system, between the conventional and bioreactor landfills, observed using the mathematical model proposed in this study, corroborates the importance of considering coupled hydro-bio-mechanical processes while designing and predicting the performance of engineered bioreactor landfills. The study underscores the importance of considering the effect of coupled processes while examining the stability and integrity of the liner and cover systems, which form the integral components of a landfill. Moreover, the spatial and temporal variations in the landfill settlement, the

  12. Broad-spectrum amino acid-sensing class C G-protein coupled receptors: molecular mechanisms, physiological significance and options for drug development.

    Science.gov (United States)

    Conigrave, Arthur D; Hampson, David R

    2010-09-01

    In this article, we consider the molecular mechanisms that underlie broad-spectrum amino acid sensing by a discrete subgroup of class C G-protein-coupled receptors that includes the calcium-sensing receptor, GPRC6A and heterodimers composed of two closely related receptor subunits, T1R(1) and T1R(3). We consider their physiological significance highlighting their diverse spectrum of cellular responses and the phenotypes of global and conditional knock-out mice. In addition, we consider strategies for the development of new drugs that target these receptors. 2010 Elsevier Inc. All rights reserved.

  13. Diffuso-Kinetics and Diffuso-Mechanics of Carbon Dioxide / Polyvinylidene Fluoride System under Explosive Gas Decompression: Identification of Key Diffuso-Elastic Couplings by Numerical and Experimental Confrontation

    Directory of Open Access Journals (Sweden)

    Grandidier Jean-Claude

    2015-02-01

    Full Text Available The work aims at identifying the key diffuso-elastic couplings which characterize a numerical tool developed to simulate the irreversible ‘Explosive Decompression Failure’ (XDF in semi-crystalline polymer. The model proposes to predict the evolution of the gas concentration and of the stress field in the polymer during the gas desorption [DOI: 10.1016/j.compositesa.2005.05.021]. Main difficulty is to couple thermal, mechanical and diffusive effects that occur simultaneously during the gas desorption. The couplings are splitting into two families: indirect coupling (i.e., phenomenology that is state variables (gas concentration, temperature, and pressure dependent. direct coupling, (i.e., diffuso-elastic coupling as polymer volume changes because of gas diffusion; The numerical prediction of the diffusion kinetics and of the volume strain (swelling of PVF2 (polyvinylidene fluoride under CO2 (carbon dioxide environment is concerned. The prediction is carried out by studying selected combinations of couplings for a broad range of CO2 pressures. The modeling relevance is evaluated by a comparison with experimental transport parameters analytically identify from solubility tests. A pertinent result of the present study is to have demonstrated the non-uniqueness of the coefficients of diffusion (D and solubility (Sg between the diffuso-elastic coupling (direct coupling and indirect coupling. Main conclusion is that it is necessary to consider concomitantly the two types of couplings, the indirect and the direct couplings.

  14. Air-coupled acoustic radiation force for non-contact generation of broadband mechanical waves in soft media

    Energy Technology Data Exchange (ETDEWEB)

    Ambroziński, Łukasz [Department of Bioengineering, University of Washington, Seattle, Washington 98195 (United States); AGH University of Science and Technology, Krakow 30059 (Poland); Pelivanov, Ivan, E-mail: ivanp3@uw.edu [Department of Bioengineering, University of Washington, Seattle, Washington 98195 (United States); Faculty of Physics, Moscow State University, Moscow 119991 (Russian Federation); Song, Shaozhen; Yoon, Soon Joon; Gao, Liang; O' Donnell, Matthew [Department of Bioengineering, University of Washington, Seattle, Washington 98195 (United States); Li, David [Department of Bioengineering, University of Washington, Seattle, Washington 98195 (United States); Department of Chemical Engineering, University of Washington Seattle, Washington 98195 (United States); Shen, Tueng T.; Wang, Ruikang K. [Department of Bioengineering, University of Washington, Seattle, Washington 98195 (United States); Department of Ophthalmology, University of Washington, Seattle, Washington 98104 (United States)

    2016-07-25

    A non-contact method for efficient, non-invasive excitation of mechanical waves in soft media is proposed, in which we focus an ultrasound (US) signal through air onto the surface of a medium under study. The US wave reflected from the air/medium interface provides radiation force to the medium surface that launches a transient mechanical wave in the transverse (lateral) direction. The type of mechanical wave is determined by boundary conditions. To prove this concept, a home-made 1 MHz piezo-ceramic transducer with a matching layer to air sends a chirped US signal centered at 1 MHz to a 1.6 mm thick gelatin phantom mimicking soft biological tissue. A phase-sensitive (PhS)-optical coherence tomography system is used to track/image the mechanical wave. The reconstructed transient displacement of the mechanical wave in space and time demonstrates highly efficient generation, thus offering great promise for non-contact, non-invasive characterization of soft media, in general, and for elasticity measurements in delicate soft tissues and organs in bio-medicine, in particular.

  15. Fundamental Processes of Coupled Radiation Damage and Mechanical Behavior in Nuclear Fuel Materials for High Temperature Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Phillpot, Simon; Tulenko, James

    2011-09-08

    The objective of this work has been to elucidate the relationship among microstructure, radiation damage and mechanical properties for nuclear fuel materials. As representative nuclear materials, we have taken an hcp metal (Mg as a generic metal, and Ti alloys for fast reactors) and UO2 (representing fuel). The degradation of the thermo-mechanical behavior of nuclear fuels under irradiation, both the fissionable material itself and its cladding, is a longstanding issue of critical importance to the nuclear industry. There are experimental indications that nanocrystalline metals and ceramics may be more resistant to radiation damage than their coarse-grained counterparts. The objective of this project look at the effect of microstructure on radiation damage and mechanical behavior in these materials. The approach to be taken was state-of-the-art, large-scale atomic-level simulation. This systematic simulation program of the effects of irradiation on the structure and mechanical properties of polycrystalline Ti and UO2 identified radiation damage mechanisms. Moreover, it will provided important insights into behavior that can be expected in nanocrystalline microstructures and, by extension, nanocomposites. The fundamental insights from this work can be expected to help in the design microstructures that are less susceptible to radiation damage and thermomechanical degradation.

  16. Receptance coupling of multi-subsystem connected via a wedge mechanism with application in the position-dependent dynamics of ballscrew drives

    Science.gov (United States)

    Liu, Hui; Lu, Dun; Zhang, Jun; Zhao, Wanhua

    2016-08-01

    An accurate model of the feed drive's high-order position-dependent dynamics is crucial for the analysis and controller design of a high-performance machine tool. In this paper, a new dynamic substructuring condition-multi-subsystem connected via a wedge mechanism is introduced, which is originated from the ballscrew-nut dynamic coupling interface. Receptance coupling equations were derived for the condition, and a dynamic modeling approach is developed for the ballscrew drive system based on the equations. The developed model accounts for the ballscrew's rotational and axial flexibilities and the dynamic couplings among these flexibilities and that of the sliding component. The model explicitly describes the dynamics variation with respect to the table position, and is particularly suitable for sensitivity based analysis. Based on the model, the position-dependent dynamics of an example ballscrew drive was analyzed, by using the frequencies distribution, the modal shape, and especially the sensitivity of the frequency response functions with respect to the table position.

  17. F···HO intramolecular hydrogen bond as the main transmission mechanism for (1h)J(F,H(O)) coupling constant in 2'-fluoroflavonol.

    Science.gov (United States)

    Fonseca, Tânia A O; Ramalho, Teodorico C; Freitas, Matheus P

    2012-08-01

    Flavonoids are useful compounds in medicinal chemistry and exhibit conformational isomerism, which is ruled by intramolecular interactions. One of the main intramolecular forces governing the stability of conformations is the hydrogen bond. Hydrogen bond involving fluorine covalently bonded to carbon has been found to be rare, but it appears in 2'-fluoroflavonol, although the F···HO hydrogen bond cannot be considered the main effect governing the conformational stability of this compound. Because (19)F is magnetically active and suitable for NMR studies, the (1h)J(F,H(O)) coupling constant can be used as a probe for such an interaction in 2'-fluoroflavonol. In fact, the (1h)J(F,H(O)) coupling was computationally analyzed in this work, and the F···HO hydrogen bond was found to be its main transmission mechanism, which modulates this coupling in 2'-fluoroflavonol, rather than overlap of proximate electronic clouds, such as in 2-fluorophenol. Copyright © 2012 John Wiley & Sons, Ltd.

  18. Male and Couple Fertility Impairment due to HPV-DNA Sperm Infection: Update on Molecular Mechanism and Clinical Impact—Systematic Review

    Directory of Open Access Journals (Sweden)

    Salvatore Gizzo

    2014-01-01

    Full Text Available Recent evidences identify Human Papillomavirus (HPV sperm infection as a possible cause of male and couple infertility. It acts through different mechanisms at various steps of human conception and early gestational development. We performed a systematic review to assess the role of HPV semen infection on male and couple infertility. Analysis of available and eligible data does not permit us to fund clear evidences about clinical impact of HPV infection on fertility, although sperm parameters impairment is the most widely recognized effect. Regarding biomolecular implications, the available data are often conflicting. More studies are required to define the role of HPV sperm infection in clinical practice. The great majority of evidences are obtained by in vitro studies and this fact