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Sample records for vibrating metal tip

  1. Ultrasonic metal welding with a vibration source using longitudinal and torsional vibration transducers

    Science.gov (United States)

    Asami, Takuya; Tamada, Yosuke; Higuchi, Yusuke; Miura, Hikaru

    2017-07-01

    Conventional ultrasonic metal welding for joining dissimilar metals uses a linear vibration locus, although this method suffers from problems such as low overall weld strength. Our previous studies have shown that ultrasonic welding with a planar vibration locus improves the weld strength. However, the vibration source in our previous studies had problems in longitudinal-torsional vibration controllability and small welding tip. Therefore, the study of the optimal shape of the vibration locus was difficult. Furthermore, improvement of weld strength cannot be expected. We have developed a new ultrasonic vibration source that can control the longitudinal-torsional vibration and can connect to a large welding tip. In this study, we clarified the longitudinal-torsional vibration controllability of the developed ultrasonic vibration source. Moreover, we clarified that using the planar locus of the developed vibration source produced a higher weld strength than our previous studies, and clarified the optimal shape of the vibration locus.

  2. Near-field infrared vibrational dynamics and tip-enhanced decoherence.

    Science.gov (United States)

    Xu, Xiaoji G; Raschke, Markus B

    2013-04-10

    Ultrafast infrared spectroscopy can reveal the dynamics of vibrational excitations in matter. In its conventional far-field implementation, however, it provides only limited insight into nanoscale sample volumes due to insufficient spatial resolution and sensitivity. Here, we combine scattering-scanning near-field optical microscopy (s-SNOM) with femtosecond infrared vibrational spectroscopy to characterize the coherent vibrational dynamics of a nanoscopic ensemble of C-F vibrational oscillators of polytetrafluoroethylene (PTFE). The near-field mode transfer between the induced vibrational molecular coherence and the metallic scanning probe tip gives rise to a tip-mediated radiative IR emission of the vibrational free-induction decay (FID). By increasing the tip–sample coupling, we can enhance the vibrational dephasing of the induced coherent vibrational polarization and associated IR emission, with dephasing times up to T2(NF) is approximately equal to 370 fs in competition against the intrinsic far-field lifetime of T2(FF) is approximately equal to 680 fs as dominated by nonradiative damping. Near-field antenna-coupling thus provides for a new way to modify vibrational decoherence. This approach of ultrafast s-SNOM enables the investigation of spatiotemporal dynamics and correlations with nanometer spatial and femtosecond temporal resolution.

  3. Scaling in light scattering by sharp conical metal tips

    CERN Document Server

    Pors, Anders; Bozhevolnyi, Sergey I

    2016-01-01

    Using the electrostatic approximation, we analyze electromagnetic fields scattered by sharp conical metal tips, which are illuminated with light polarized along the tip axis. We establish scaling relations for the scattered field amplitude and phase, whose validity is verified with numerical simulations. Analytic expressions for the wavelength, at which the scattered field near the tip changes its direction, and field decay near the tip extremity are obtained, relating these characteristics to the cone angle and metal permittivity. The results obtained have important implications to various tip-enhanced phenomena, ranging from Raman and scattering near-field imaging to photoemission spectroscopy and nano-optical trapping.

  4. Detection of surface-plasmon evanescent fields using a metallic probe tip covered with fluorescence

    CERN Document Server

    Wakamatsu, T; Shinbo, K; Kato, K; Kaneko, F

    1999-01-01

    A new experimental system has been constructed to detect evanescent fields of metal surface plasmons (SPs) using a metallic probe tip covered with fluorescence cadmium sulfide (CdS). The evanescent fields of the SPs sensitive to the metal interfaces were observed as fluorescent light from CdS on the tip. No additional lock-in detection technique with a vibrating probe tip is necessary in the system, in spite of the scattered light enhanced by SP due to the surface roughness. The fluorescent light measured for the Al film sample shows exponential decay with distance from the sample surface, indicating that the SP evanescent fields are detected with our apparatus. (10 refs).

  5. Vibration of a hanging tapered string with or without tip mass

    Energy Technology Data Exchange (ETDEWEB)

    Wang, C Y, E-mail: cywang@math.msu.edu [Departments of Mathematics, Michigan State University, East Lansing, MI 48824 (United States)

    2011-09-15

    A vibrating hanging tapered string (chord, chain, cable) is studied both analytically and numerically. The proper boundary condition for a tip-mass-less string is derived. It is found that the frequencies depend heavily on the taper, tip mass and the shape of the cross section. (letters and comments)

  6. Random Vibration Analysis of the Tip-tilt System in the GMT Fast Steering Secondary Mirror

    Science.gov (United States)

    Lee, Kyoung-Don; Kim, Young-Soo; Kim, Ho-Sang; Lee, Chan-Hee; Lee, Won Gi

    2017-09-01

    A random vibration analysis was accomplished on the tip-tilt system of the fast steering secondary mirror (FSM) for the Giant Magellan Telescope (GMT). As the FSM was to be mounted on the top end of the secondary truss and disturbed by the winds, dynamic effects of the FSM disturbances on the tip-tilt correction performance was studied. The coupled dynamic responses of the FSM segments were evaluated with a suggested tip-tilt correction modeling. Dynamic equations for the tip-tilt system were derived from the force and moment equilibrium on the segment mirror and the geometric compatibility conditions with four design parameters. Statically stationary responses for the tip-tilt actuations to correct the wind-induced disturbances were studied with two design parameters based on the spectral density function of the star image errors in the frequency domain. Frequency response functions and root mean square values of the dynamic responses and the residual star image errors were numerically calculated for the off-axis and on-axis segments of the FSM. A prototype of on-axis segment of the FSM was developed for tip-tilt actuation tests to confirm the ratio of tip-tilt force to tip-tilt angle calculated from the suggested dynamic equations of the tip-tilt system. Tip-tilt actuation tests were executed at 4, 8 and 12 Hz by measuring displacements of piezoelectric actuators and reaction forces acting on the axial supports. The derived ratios of rms tip-tilt force to rms tip-tilt angle from tests showed a good correlation with the numerical results. The suggested process of random vibration analysis on the tip-tilt system to correct the wind-induced disturbances of the FSM segments would be useful to advance the FSM design and upgrade the capability to achieve the least residual star image errors by understanding the details of dynamics.

  7. Vibration assisted femtosecond laser machining on metal

    Science.gov (United States)

    Park, Jung-Kyu; Yoon, Ji-Wook; Cho, Sung-Hak

    2012-06-01

    We demonstrate a novel approach to improve laser machining quality on metals by vibrating the optical objective lens with a frequency (of 500 Hz) and various displacements (0-16.5 μm) during a femtosecond laser machining process. The laser used in this experiment is an amplified Ti:sapphire fs laser system that generates 100 fs pulses having an energy of 3.5 mJ/pulse with a 5 kHz repetition rate at a central wavelength of 790 nm. It is found that both the wall surface finish of the machined structures and the aspect ratio obtained using the frequency vibration assisted laser machining are improved, compared to those derived via laser machining without vibration assistance. This is the first report of low frequency vibration of an optical objective lens in the femtosecond laser machining process being exploited to obtain significantly improved surface roughness of machined side walls and increased aspect ratios.

  8. Characterizing the free and surface-coupled vibrations of heated-tip atomic force microscope cantilevers.

    Science.gov (United States)

    Killgore, Jason P; Tung, Ryan C; Hurley, Donna C

    2014-08-29

    Combining heated-tip atomic force microscopy (HT-AFM) with quantitative methods for determining surface mechanical properties, such as contact resonance force microscopy, creates an avenue for nanoscale thermomechanical property characterization. For nanomechanical methods that employ an atomic force microscope cantilever's vibrational modes, it is essential to understand how the vibrations of the U-shaped HT-AFM cantilever differ from those of a more traditional rectangular lever, for which analytical techniques are better developed. Here we show, with a combination of finite element analysis (FEA) and experiments, that the HT-AFM cantilever exhibits many more readily-excited vibrational modes over typical AFM frequencies compared to a rectangular cantilever. The arms of U-shaped HT-AFM cantilevers exhibit two distinct forms of flexural vibrations that differ depending on whether the two arms are vibrating in-phase or out-of-phase with one another. The in-phase vibrations are qualitatively similar to flexural vibrations in rectangular cantilevers and generally show larger sensitivity to surface stiffness changes than the out-of-phase vibrations. Vibration types can be identified from their frequency and by considering vibration amplitudes in the horizontal and vertical channels of the AFM at different laser spot positions on the cantilever. For identifying contact resonance vibrational modes, we also consider the sensitivity of the resonant frequencies to a change in applied force and hence to tip-sample contact stiffness. Finally, we assess how existing analytical models can be used to accurately predict contact stiffness from contact-resonance HT-AFM results. A simple two-parameter Euler-Bernoulli beam model provided good agreement with FEA for in-phase modes up to a contact stiffness 500 times the cantilever spring constant. By providing insight into cantilever vibrations and exploring the potential of current analysis techniques, our results lay the groundwork

  9. Nonlinear Vibration Characteristics of a Flexible Blade with Friction Damping due to Tip-Rub

    Directory of Open Access Journals (Sweden)

    Dengqing Cao

    2011-01-01

    Full Text Available An approximate approach is proposed in this paper for analyzing the two-dimensional friction contact problem so as to compute the dynamic response of a structure constrained by friction interfaces due to tip-rub. The dynamical equation of motion for a rotational cantilever blade in a centrifugal force field is established. Flow-induced distributed periodic forces and the internal material damping in the blade are accounted for in the governing equation of motion. The Galerkin method is employed to obtain a three-degree-of-freedom oscillator with friction damping due to tip-rub. The combined motion of impact and friction due to tip-rub produced a piecewise linear vibration which is actually nonlinear. Thus, a complete vibration cycle is divided into successive intervals. The system possesses linear vibration characteristic during each of these intervals, which can be determined using analytical solution forms. Numerical simulation shows that the parameters such as gap of the tip and the rotational speed of the blades have significant effects on the dynamical responses of the system. Finally, the nonlinear vibration characteristics of the blade are investigated in terms of the Poincare graph, and the frequency spectrum of the responses and the amplitude-frequency curves.

  10. Transverse Free Vibration of Axially Moving Stepped Beam with Different Length and Tip Mass

    Directory of Open Access Journals (Sweden)

    Guoliang Ma

    2015-01-01

    Full Text Available Axially moving stepped beam (AMSB with different length and tip mass is represented by adopting Euler-Bernoulli beam theory, and its characteristics and displacements of transverse free vibration are calculated by using semianalytical method. Firstly, the governing equation of the transverse free vibration is established based on Hamilton’s principle. The equation is cast into eigenvalue equation through the complex modal analysis. Then, a scheme is proposed to derive the continuous condition accordingly as the displacement, rotation, bending moment, and shear force are all equal at the connections of any two segments. Another scheme is to derive frequency equation from the given boundary conditions which contain a tip mass in the last segment. Finally, the natural frequency and modal function are calculated by using numerical method according to the eigenvalue equation and frequency equation. Due to the introduction of modal truncation, displacement and, the free vibration solution can be obtained by adopting modal superposition after Hilbert transform. The numerical examples illustrate that length, velocity, mass, and geometry affect characteristics and displacements significantly; the series of methods are effective and accurate to investigate the vibration of the AMSB with different length and tip mass after comparing several results.

  11. High-tip-speed fiber composite compressor blades: Vibration and strength analysis

    Science.gov (United States)

    Chamis, C. C.; Lynch, J. E.

    1974-01-01

    An analytical procedure is described which couples composite mechanics computer codes with NASTRAN. This procedure was used to perform a detailed analysis of a high-tip-speed fiber composite compressor fan blade. The results indicate that the various vibration modes of this blade are highly coupled. Mechanical load ply stresses are well below the corresponding room temperature strengths. Lamination residual stresses are likely to cause transply cracks and interply delamination. Transply cracks and relaxation of root fixity decrease the vibrational frequencies whereas centrifugal stiffening increases them. Comparisons of results for various parameters are presented in tabular and graphical form.

  12. Apparently the first closed-form solution of vibrating inhomogeneous beam with a tip mass

    Science.gov (United States)

    Elishakoff, I.; Johnson, V.

    2005-09-01

    Whereas there are numerous papers on the free vibrations of beams of uniform or non-uniform cross-section carrying concentrated masses, the problem does not lend itself to the closed-form solution. Here such a solution is reported, apparently for the first time. The solution originally derived for the inhomogeneous beam without a concentrated mass is generalized to include a tip mass. The semi-inverse method is utilized, to achieve this goal.

  13. Vibrational Properties of a Monolayer Silicene Sheet Studied by Tip-Enhanced Raman Spectroscopy

    Science.gov (United States)

    Sheng, Shaoxiang; Wu, Jiang-bin; Cong, Xin; Li, Wenbin; Gou, Jian; Zhong, Qing; Cheng, Peng; Tan, Ping-heng; Chen, Lan; Wu, Kehui

    2017-11-01

    Combining ultrahigh sensitivity, spatial resolution, and the capability to resolve chemical information, tip-enhanced Raman spectroscopy (TERS) is a powerful tool to study molecules or nanoscale objects. Here we show that TERS can also be a powerful tool in studying two-dimensional materials. We have achieved a 109 Raman signal enhancement and a 0.5 nm spatial resolution using monolayer silicene on Ag(111) as a prototypical 2D material system. Because of the selective enhancement on Raman modes with vertical vibrational components in TERS, our experiment provides direct evidence of the origination of Raman modes in silicene. Furthermore, the ultrahigh sensitivity of TERS allows us to identify different vibrational properties of silicene phases, which differ only in the bucking direction of the Si-Si bonds. Local vibrational features from defects and domain boundaries in silicene can also be identified.

  14. Resonances of nanoparticles with poor plasmonic metal tips.

    Science.gov (United States)

    Ringe, Emilie; DeSantis, Christopher J; Collins, Sean M; Duchamp, Martial; Dunin-Borkowski, Rafal E; Skrabalak, Sara E; Midgley, Paul A

    2015-11-30

    The catalytic and optical properties of metal nanoparticles can be combined to create platforms for light-driven chemical energy storage and enhanced in-situ reaction monitoring. However, the heavily damped plasmon resonances of many catalytically active metals (e.g. Pt, Pd) prevent this dual functionality in pure nanostructures. The addition of catalytic metals at the surface of efficient plasmonic particles thus presents a unique opportunity if the resonances can be conserved after coating. Here, nanometer resolution electron-based techniques (electron energy loss, cathodoluminescence, and energy dispersive X-ray spectroscopy) are used to show that Au particles incorporating a catalytically active but heavily damped metal, Pd, sustain multiple size-dependent localized surface plasmon resonances (LSPRs) that are narrow and strongly localized at the Pd-rich tips. The resonances also couple with a dielectric substrate and other nanoparticles, establishing that the full range of plasmonic behavior is observed in these multifunctional nanostructures despite the presence of Pd.

  15. Resonances of nanoparticles with poor plasmonic metal tips

    Science.gov (United States)

    Ringe, Emilie; Desantis, Christopher J.; Collins, Sean M.; Duchamp, Martial; Dunin-Borkowski, Rafal E.; Skrabalak, Sara E.; Midgley, Paul A.

    2015-11-01

    The catalytic and optical properties of metal nanoparticles can be combined to create platforms for light-driven chemical energy storage and enhanced in-situ reaction monitoring. However, the heavily damped plasmon resonances of many catalytically active metals (e.g. Pt, Pd) prevent this dual functionality in pure nanostructures. The addition of catalytic metals at the surface of efficient plasmonic particles thus presents a unique opportunity if the resonances can be conserved after coating. Here, nanometer resolution electron-based techniques (electron energy loss, cathodoluminescence, and energy dispersive X-ray spectroscopy) are used to show that Au particles incorporating a catalytically active but heavily damped metal, Pd, sustain multiple size-dependent localized surface plasmon resonances (LSPRs) that are narrow and strongly localized at the Pd-rich tips. The resonances also couple with a dielectric substrate and other nanoparticles, establishing that the full range of plasmonic behavior is observed in these multifunctional nanostructures despite the presence of Pd.

  16. Simulated Tip Rub Testing of Low-Density Metal Foam

    Science.gov (United States)

    Bowman, Cheryl L.; Jones, Michael G.

    2009-01-01

    Preliminary acoustic studies have indicated that low-density, open-cell, metal foams may be suitable acoustic liner material for noise suppression in high by-pass engines. Metal foam response under simulated tip rub conditions was studied to assess whether its durability would be sufficient for the foam to serve both as a rub strip above the rotor as well as an acoustic treatment. Samples represented four metal alloys, nominal cell dimensions ranging from 60 to 120 cells per inch (cpi), and relative densities ranging from 3.4 to 10 percent. The resulting rubbed surfaces were relatively smooth and the open cell structure of the foam was not adversely affected. Sample relative density appeared to have significant influence on the forces induced by the rub event. Acoustic responses of various surface preparations were measured using a normal incidence tube. The results of this study indicate that the foam s open-cell structure was retained after rubbing and that the acoustic absorption spectra variation was minimal.

  17. Thermal Diffusion Processes in Metal-Tip-Surface Interactions: Contact Formation and Adatom Mobility

    DEFF Research Database (Denmark)

    Sørensen, Mads Reinholdt; Jacobsen, Karsten Wedel; Jonsson, Hannes

    1996-01-01

    We have carried out computer simulations to identify and characterize various thermally activated atomic scale processes that can play an important role in room temperature experiments where a metal tip is brought close to a metal surface. We find that contact formation between the tip and the su...

  18. Metal Ir coatings on endocardial electrode tips, obtained by MOCVD

    Science.gov (United States)

    Vikulova, Evgeniia S.; Kal'nyi, Danila B.; Shubin, Yury V.; Kokovkin, Vasily V.; Morozova, Natalya B.; Hassan, Aseel; Basova, Tamara V.

    2017-12-01

    The present work demonstrates the application of the Metal-Organic Chemical Vapor Deposition technique to fabricate metal iridium coatings onto the pole tips of endocardial electrodes. Using iridium (III) acetylacetonate as a volatile precursor, the target coatings were successfully applied to the working surface of cathodes and anodes of pacemaker electrodes in the flow type reactor in hydrogen atmosphere at deposition temperature of 550 °C. The coating samples were characterized by means of XRD, SEM, Raman- and XPS-spectroscopies. The formation of non-textured coatings with fractal-like morphology and 7-24 nm crystallite size has been realized. The electrochemical properties of the coatings were investigated by cyclic voltammetry and electrochemical impedance spectroscopy. The charge storage capacity values of the electrochemically activated samples were 17.0-115 mC cm-2 and 14.4-76.5 mC cm-2 for measurements carried out in 0.1 M sulfuric acid and in phosphate buffer saline solutions, respectively. A comparison of some characteristics of the samples obtained with commercially available cathode of pacemaker electrodes is also presented.

  19. On the nature of AFM tip metal-MoS2 contact; effect of single layer character and tip force

    Science.gov (United States)

    Kaushik, Vishakha; Varandani, Deepak; Das, Pintu; Mehta, Bodh R.

    2017-10-01

    In the present study, the nature of metal-MoS2 contacts has been investigated using conductive atomic force microscopy. The point I-V characteristics have been acquired as a function of loading force (53 nN-252 nN) for an interface formed between the atomic force microscopy (AFM) tip (Pt and Co coated) and MoS2 domains (single and multilayer). The metal-MoS2 junctions for both Co and Pt tips exhibit a rectifying nature with higher forward current for the Co tip as compared to the Pt tip for both single and multilayer samples. An interesting behavior of decreasing junction current and rectification ratio with increasing tip loading force is observed in the case of single layer MoS2. In comparison, negligible or very small change in the forward junction current is observed in the case of multilayer samples. The single layer MoS2 undergoes charge polarization in the presence of uniaxial strain exerted in the form of AFM tip loading force, resulting in current in a direction opposite to the forward current due to the migration of majority electron carriers away from the tip-MoS2 interface. Therefore, the net current which is a sum of the forward junction current and the force induced current reduces with loading force for single layer MoS2. This study emphasizes the influence of the single layer nature of MoS2 on the electrical properties of metal-MoS2 contacts, an understanding of which is important from the perspective of basic physics and its applications.

  20. Sparse Representation Based Frequency Detection and Uncertainty Reduction in Blade Tip Timing Measurement for Multi-Mode Blade Vibration Monitoring

    Science.gov (United States)

    Pan, Minghao; Yang, Yongmin; Guan, Fengjiao; Hu, Haifeng; Xu, Hailong

    2017-01-01

    The accurate monitoring of blade vibration under operating conditions is essential in turbo-machinery testing. Blade tip timing (BTT) is a promising non-contact technique for the measurement of blade vibrations. However, the BTT sampling data are inherently under-sampled and contaminated with several measurement uncertainties. How to recover frequency spectra of blade vibrations though processing these under-sampled biased signals is a bottleneck problem. A novel method of BTT signal processing for alleviating measurement uncertainties in recovery of multi-mode blade vibration frequency spectrum is proposed in this paper. The method can be divided into four phases. First, a single measurement vector model is built by exploiting that the blade vibration signals are sparse in frequency spectra. Secondly, the uniqueness of the nonnegative sparse solution is studied to achieve the vibration frequency spectrum. Thirdly, typical sources of BTT measurement uncertainties are quantitatively analyzed. Finally, an improved vibration frequency spectra recovery method is proposed to get a guaranteed level of sparse solution when measurement results are biased. Simulations and experiments are performed to prove the feasibility of the proposed method. The most outstanding advantage is that this method can prevent the recovered multi-mode vibration spectra from being affected by BTT measurement uncertainties without increasing the probe number. PMID:28758952

  1. Evaluation of the safety and efficiency of novel metallic implant scaler tips manufactured by the powder injection molding technique.

    Science.gov (United States)

    Chun, Kyung A; Kum, Kee-Yeon; Lee, Woo-Cheol; Baek, Seung-Ho; Choi, Hae-Won; Shon, Won-Jun

    2017-07-11

    Although many studies have compared the properties of ultrasonic scaling instruments, it remains controversial as to which is most suitable for implant scaling. This study evaluated the safety and efficiency of novel metallic ultrasonic scaler tips made by the powder injection molding (PIM) technique on titanium surfaces. Mechanical instrumentation was carried out using four types of metal scaler tips consisting of copper (CU), bronze (BR), 316 L stainless steel (316 L), and conventional stainless steel (SS) tips. The instrumented surface alteration image of samples was viewed with scanning electron microscope (SEM) and surface profile of the each sample was investigated with confocal laser scanning microscopy (CLSM). Arithmetic mean roughness (Ra) and maximum height roughness (Rmax) of titanium samples were measured and dissipated power of the scaler tip was estimated for scaling efficiency. The average Ra values caused by the 316 L and SS tip were about two times higher than those of the CU and BR tips (p < 0.05). The Rmax value showed similar results. The efficiency of the SS tip was about 3 times higher than that of CU tip, the 316 L tip is about 2.7 times higher than that of CU tip, and the BR tip is about 1.2 times higher than that of CU tip. Novel metallic bronze alloy ultrasonic scaler tip minimally damages titanium surfaces, similar to copper alloy tip. Therefore, this bronze alloy scaler tip may be promising instrument for implant maintenance therapy.

  2. Compact metal probes: a solution for atomic force microscopy based tip-enhanced Raman spectroscopy.

    Science.gov (United States)

    Rodriguez, R D; Sheremet, E; Müller, S; Gordan, O D; Villabona, A; Schulze, S; Hietschold, M; Zahn, D R T

    2012-12-01

    There are many challenges in accomplishing tip-enhanced Raman spectroscopy (TERS) and obtaining a proper tip is probably the greatest one. Since tip size, composition, and geometry are the ultimate parameters that determine enhancement of intensity and lateral resolution, the tip becomes the most critical component in a TERS experiment. However, since the discovery of TERS the cantilevers used in atomic force microscopy (AFM) have remained basically the same: commercial silicon (or silicon nitride) tips covered by a metallic coating. The main issues of using metal-coated silicon cantilevers, such as wearing off of the metal layer or increased tip radius, can be completely overcome by using all-metal cantilevers. Until now in TERS experiments such probes have only been used in a scanning tunneling microscope or in a tuning fork-based shear force microscope but not in AFM. In this work for the first time, we show the use of compact silver cantilevers that are fully compatible with contact and tapping modes in AFM demonstrating their superb performance in TERS experiments.

  3. Strength and Dislocation Structure Evolution of Small Metals under Vibrations

    Science.gov (United States)

    Ngan, Alfonso

    2015-03-01

    It is well-known that ultrasonic vibration can soften metals, and this phenomenon has been widely exploited in industrial applications concerning metal forming and bonding. In this work, we explore the effects of a superimposed small oscillatory load on metal plasticity, from the nano- to macro-size range, and from audible to ultrasonic frequency ranges. Macroscopic and nano-indentation were performed on aluminum, copper and molybdenum, and the results show that the simultaneous application of oscillatory stresses can lower the hardness of these samples. More interestingly, EBSD and TEM observations show that subgrain formation and reduction in dislocation density generally occurred when stress oscillations were applied. These findings point to an important knowledge gap in metal plasticity - the existing understanding of ultrasound softening in terms of the vibrations either imposing additional stress waves to augment the quasi-static applied load, or heating up the metal, whereas the metal's intrinsic deformation resistance or dislocation interactive processes are assumed unaltered by the ultrasound, is proven wrong by the present results. Furthermore, in the case of nanoindentation, the Continuous Stiffness Measurement technique for contact stiffness measurement assumes that the imposed signal-carrier oscillations do not intrinsically alter the material properties of the specimen, and again, the present results prove that this can be wrong. To understand the enhanced subgrain formation and dislocation annihilation, Discrete Dislocation Dynamics (DDD) simulations were carried out and these show that when an oscillatory stress is superimposed on a quasi-static applied stress, reversals of motion of dislocations may occur, and these allow the dislocations to revisit repeatedly suitable configurations for annihilation. DDD, however, was unable to predict the observed subgrain formation presumably because the number of dislocations that can be handled is not large

  4. Effect of mechanical and electrical stimuli in conductive atomic force microscopy with noble metal-coated tips

    Science.gov (United States)

    Zade, Vishal; Kang, Hung-Sen; Lee, Min Hwan

    2018-01-01

    Conductive atomic force microscopy has been widely employed to study the localized electrical properties of a wide range of substrates in non-vacuum conditions by the use of noble metal-coated tips. However, quantitative characterization of the electrical properties was often precluded by unpredictable changes in the tip apex morphology, and/or electronic transport characteristics of undesired oxide overcoats on the tip. In this paper, the impact of mechanical and electrical stimuli on the apex geometry of gold coated tips and electrical conduction properties at the tip-substrate contact is discussed by choosing gold and highly ordered pyrolytic graphite as the representative tip and substrate materials, respectively.

  5. Coherent XUV generation driven by sharp metal tips photoemission

    CERN Document Server

    Ciappina, M F; Shaaran, T; Lewenstein, M

    2014-01-01

    It was already experimentally demonstrated that high-energy electrons can be generated using metal nanotips as active media. In addition, it has been theoretically proven that the high-energy tail of the photoemitted electrons is intrinsically linked to the recollision phenomenon. Through this recollision process it is also possible to convert the energy gained by the laser-emitted electron in the continuum in a coherent XUV photon. It means the emission of harmonic radiation appears to be feasible, although it has not been experimentally demonstrated hitherto till now. In this paper, we employ a quantum mechanical approach to model the electron dipole moment including both the laser experimental conditions and the bulk matter properties and predict is possible to generate coherent UV and XUV radiation using metal nanotips as sources. Our quantum mechanical results are fully supported by their classical counterparts.

  6. Subsurface metals fatigue cracking without and with crack tip

    Directory of Open Access Journals (Sweden)

    Andrey Shanyavskiy

    2013-07-01

    Full Text Available Very-High-Cycle-Fatigue regime for metals was considered and mechanisms of the subsurface crack origination were introduced. In many metals first step of crack origination takes place with specific area formation because of material pressing and rotation that directed to transition in any volume to material ultra-high-plasticity with nano-structure appearing. Then by the border of the nano-structure takes place volume rotation and fracture surface creates with spherical particles which usually named Fine-Granular-Area. In another case there takes place First-Smooth-Facet occurring in area of origin due to whirls appearing by the one of the slip systems under discussed the same stress-state conditions. Around Fine-Granular-Area or First-Smooth-Facet there plastic zone appeared and, then, subsurface cracking develops by the same manner as for through cracks. In was discussed quantum-mechanical nature of fatigue crack growth in accordance with Yang’s modulus quantization for low level of deformations. New simply equation was considered for describing subsurface cracking in metals out of Fine-Granular-Area or Fist-Smooth-Facet.

  7. Effect of tip vortices on membrane vibration of flexible wings with different aspect ratios

    Directory of Open Access Journals (Sweden)

    Genç Mustafa Serdar

    2016-01-01

    Full Text Available In this study, the effect of the aspect ratio on the aerodynamics characteristic of flexible membrane wings with different aspect ratios (AR = 1 and AR = 3 is experimentally investigated at Reynolds number of 25000. Time accurate measurements of membrane deformation using Digital Image Correlation system (DIC is carried out while normal forces of the wing will be measured by helping a load-cell system and flow on the wing was visualized by means of smoke wire technic. The characteristics of high aspect ratio wings are shown to be affected by leading edge separation bubbles at low Reynolds number. It is concluded that the camber of membrane wing excites the separated shear layer and this situation increases the lift coefficient relatively more as compared to rigid wings. In membrane wings with low aspect ratio, unsteadiness included tip vortices and vortex shedding, and the combination of tip vortices and vortex shedding causes complex unsteady deformations of these membrane wings. The characteristic of high aspect ratio wings was shown to be affected by leading edge separation bubbles at low Reynolds numbers whereas the deformations of flexible wing with low aspect ratio affected by tip vortices and leading edge separation bubbles.

  8. Theoretical model of the tunneling current between a metallic tip and a ferroelectric material.

    Science.gov (United States)

    Neupane, Ravi; Yost, Andrew; Chien, Teyu

    We present a model to calculate the tunneling current for a ferroelectric (FE) material in a metal/vacuum/Ferroelectric tunneling junction. Using this model, we try to explore the effect of the FE dipole orientation's direction on I - V spectrum using scanning tunneling spectroscopy (STS). The STM tunneling current for non-FE materials depends upon various factors such as tip -sample distance (vacuum gap), temperature, density of states (DOS) of tip and of sample, and tip-sample bias. FE materials have internal electric dipoles giving rise to internal and external electric fields. The electric field induced by these dipoles will distort the fermi level as a function of depth in the material. In our model, the Fermi level is assumed to be inclined with a slope as a function of the depth. The slope depends upon the orientation and the strength of the electric dipole moment. In this model we use the WKB method accounting for the slope of the fermi level to calculate the tunneling probability from tip to different depths then summing all contributions to obtain the total current as a function of tip-sample bias, i.e. I - V curves. School of Energy Resources, University of Wyoming.

  9. Bandwidth Widening of Piezoelectric Cantilever Beam Arrays by Mass-Tip Tuning for Low-Frequency Vibration Energy Harvesting

    Directory of Open Access Journals (Sweden)

    Eduard Dechant

    2017-12-01

    Full Text Available Wireless sensor networks usually rely on internal permanent or rechargeable batteries as a power supply, causing high maintenance efforts. An alternative solution is to supply the entire system by harvesting the ambient energy, for example, by transducing ambient vibrations into electric energy by virtue of the piezoelectric effect. The purpose of this paper is to present a simple engineering approach for the bandwidth optimization of vibration energy harvesting systems comprising multiple piezoelectric cantilevers (PECs. The frequency tuning of a particular cantilever is achieved by changing the tip mass. It is shown that the bandwidth enhancement by mass tuning is limited and requires several PECs with close resonance frequencies. At a fixed frequency detuning between subsequent PECs, the achievable bandwidth shows a saturation behavior as a function of the number of cantilevers used. Since the resonance frequency of each PEC is different, the output voltages at a particular excitation frequency have different amplitudes and phases. A simple power-transfer circuit where several PECs with an individual full wave bridge rectifier are connected in parallel allows one to extract the electrical power close to the theoretical maximum excluding the diode losses. The experiments performed on two- and three-PEC arrays show reasonable agreement with simulations and demonstrate that this power-transfer circuit additionally influences the frequency dependence of the harvested electrical power.

  10. Fatigue failure in metal bellows due to flow-induced vibrations

    Science.gov (United States)

    Daniels, C. M.; Fargo, C. G.

    1969-01-01

    To prevent fatigue due to flow-induced vibrations in metal bellows connected to ducts carrying liquid hydrogen, a study was made which shows that the flexure lines are in general a function of the vibration coupling between the fluid and bellows structure, and the nature of the external environment.

  11. Demonstration of an ultra-wideband optical fiber inline polarizer with metal nano-grid on the fiber tip.

    Science.gov (United States)

    Lin, Yongbin; Guo, Junpeng; Lindquist, Robert G

    2009-09-28

    Dramatic increase in the bandwidth of optical fiber inline polarizer can be achieved by using metal nano-grid on the fiber tip. However, high extinction ratio of such fiber polarizer requires high spatial frequency metal nano girds with high aspect ratio on the small area of optical fiber tip. We report the development of a nano-fabrication process on the optical fiber tip, and the design and realization of the first ultra-wideband fiber inline polarization device with Au nano gird fabricated on a single mode optical fiber end face.

  12. Analyzing the vibrational response of an AFM cantilever in liquid with the consideration of tip mass by comparing the hydrodynamic and contact repulsive force models in higher modes

    Science.gov (United States)

    Korayem, Moharam Habibnejad; Nahavandi, Amir

    2017-04-01

    This paper investigates the vibration of a tapping-mode Atomic Force Microscope (AFM) cantilever covered with two whole piezoelectric layers in a liquid medium. The authors of this article have already modeled the vibration of a cantilever immersed in liquid over rough surfaces. Five new ideas have been considered for improving the results of the previous work. Mass and damping of a cantilever probe tip have been considered. Since the probe tip of an AFM cantilever has a mass, which can itself affect the natural frequency of vibration, the significance of this mass has been explored. Also, two hydrodynamic force models for analyzing the mass and damping added to a cantilever in liquid medium have been evaluated. In modeling the vibration of a cantilever in liquid, simplifications are made to the theoretical equations used in the modeling, which may make the obtained results different from those in the real case. So, two hydrodynamic force models are introduced and compared with each other. In addition to the already introduced DMT model, the JKR model has been proposed. The forces acting on a probe tip have attractive and repulsive effects. The attractive Van der Waals force can vary depending on the surface smoothness or roughness, and the repulsive contact force, which is independent of the type of surface roughness and usually varies with the hardness or softness of a surface. When the first mode is used in the vibration of an AFM cantilever, the changes of the existing physical parameters in the simulation do not usually produce a significant difference in the response. Thus, three cantilever vibration modes have been investigated. Finally, an analytical approach for obtaining the response of equations is presented which solves the resulting motion equation by the Laplace method and, thus, a time function is obtained for cantilever deflection is determined. Also, using the COMSOL software to model a cantilever in a liquid medium, the computed natural

  13. Etching of semiconductors and metals by the photonic jet with shaped optical fiber tips

    Science.gov (United States)

    Pierron, Robin; Lecler, Sylvain; Zelgowski, Julien; Pfeiffer, Pierre; Mermet, Frédéric; Fontaine, Joël

    2017-10-01

    The etching of semiconductors and metals by a photonic jet (PJ) generated with a shaped optical fiber tip is studied. Etched marks with a diameter of 1 μm have been realized on silicon, stainless steel and titanium with a 35 kHz pulsed laser, emitting 100 ns pulses at 1064 nm. The selection criteria of the fiber and its tip are discussed. We show that a 100/140 silica fiber is a good compromise which takes into account the injection, the working distance and the energy coupled in the higher-order modes. The energy balance is performed on the basis of the known ablation threshold of the material. Finally, the dependence between the etching depth and the number of pulses is studied. Saturation is observed probably due to a redeposition of the etched material, showing that a higher pulse energy is required for deeper etchings.

  14. Assessment of the vibration on the foam legged and sheet metal-legged passenger seat

    Directory of Open Access Journals (Sweden)

    L. Dahil

    2015-10-01

    Full Text Available In this study, it was aim ed to decrease the vibration reaching to passenger from the legs of vehicle seats. In order to determine the levels of vibrations reaching at passengers, a test pad placed under the passenger seat was used, and HVM100 device was used for digitizing the information obtained. By transferring the vibration data to system by using HVM100 device, the acceleration graphics were prepared with Blaze software. As a result, it was determined that the acceleration values of seat legs made of foam material were lower than that of seat legs made of 2 mm thick sheet metal, so they damped the vibration better.

  15. Attosecond-controlled photoemission from metal nanowire tips in the few-electron regime

    KAUST Repository

    Ahn, B.

    2017-02-07

    Metal nanotip photoemitters have proven to be versatile in fundamental nanoplasmonics research and applications, including, e.g., the generation of ultrafast electron pulses, the adiabatic focusing of plasmons, and as light-triggered electron sources for microscopy. Here, we report the generation of high energy photoelectrons (up to 160 eV) in photoemission from single-crystalline nanowire tips in few-cycle, 750-nm laser fields at peak intensities of (2-7.3) × 1012 W/cm2. Recording the carrier-envelope phase (CEP)-dependent photoemission from the nanowire tips allows us to identify rescattering contributions and also permits us to determine the high-energy cutoff of the electron spectra as a function of laser intensity. So far these types of experiments from metal nanotips have been limited to an emission regime with less than one electron per pulse. We detect up to 13 e/shot and given the limited detection efficiency, we expect up to a few ten times more electrons being emitted from the nanowire. Within the investigated intensity range, we find linear scaling of cutoff energies. The nonlinear scaling of electron count rates is consistent with tunneling photoemission occurring in the absence of significant charge interaction. The high electron energy gain is attributed to field-induced rescattering in the enhanced nanolocalized fields at the wires apex, where a strong CEP-modulation is indicative of the attosecond control of photoemission.

  16. Reversible mechano-electrochemical writing of metallic nanostructures with the tip of an atomic force microscope

    Directory of Open Access Journals (Sweden)

    Christian Obermair

    2012-12-01

    Full Text Available We recently introduced a method that allows the controlled deposition of nanoscale metallic patterns at defined locations using the tip of an atomic force microscope (AFM as a “mechano-electrochemical pen”, locally activating a passivated substrate surface for site-selective electrochemical deposition. Here, we demonstrate the reversibility of this process and study the long-term stability of the resulting metallic structures. The remarkable stability for more than 1.5 years under ambient air without any observable changes can be attributed to self-passivation. After AFM-activated electrochemical deposition of copper nanostructures on a polycrystalline gold film and subsequent AFM imaging, the copper nanostructures could be dissolved by reversing the electrochemical potential. Subsequent AFM-tip-activated deposition of different copper nanostructures at the same location where the previous structures were deleted, shows that there is no observable memory effect, i.e., no effect of the previous writing process on the subsequent writing process. Thus, the four processes required for reversible information storage, “write”, “read”, “delete” and “re-write”, were successfully demonstrated on the nanometer scale.

  17. Attosecond-controlled photoemission from metal nanowire tips in the few-electron regime

    Science.gov (United States)

    Ahn, B.; Schötz, J.; Kang, M.; Okell, W. A.; Mitra, S.; Förg, B.; Zherebtsov, S.; Süßmann, F.; Burger, C.; Kübel, M.; Liu, C.; Wirth, A.; Di Fabrizio, E.; Yanagisawa, H.; Kim, D.; Kim, B.; Kling, M. F.

    2017-03-01

    Metal nanotip photoemitters have proven to be versatile in fundamental nanoplasmonics research and applications, including, e.g., the generation of ultrafast electron pulses, the adiabatic focusing of plasmons, and as light-triggered electron sources for microscopy. Here, we report the generation of high energy photoelectrons (up to 160 eV) in photoemission from single-crystalline nanowire tips in few-cycle, 750-nm laser fields at peak intensities of (2-7.3) × 1012 W/cm2. Recording the carrier-envelope phase (CEP)-dependent photoemission from the nanowire tips allows us to identify rescattering contributions and also permits us to determine the high-energy cutoff of the electron spectra as a function of laser intensity. So far these types of experiments from metal nanotips have been limited to an emission regime with less than one electron per pulse. We detect up to 13 e/shot and given the limited detection efficiency, we expect up to a few ten times more electrons being emitted from the nanowire. Within the investigated intensity range, we find linear scaling of cutoff energies. The nonlinear scaling of electron count rates is consistent with tunneling photoemission occurring in the absence of significant charge interaction. The high electron energy gain is attributed to field-induced rescattering in the enhanced nanolocalized fields at the wires apex, where a strong CEP-modulation is indicative of the attosecond control of photoemission.

  18. Spline-based Rayleigh-Ritz methods for the approximation of the natural modes of vibration for flexible beams with tip bodies

    Science.gov (United States)

    Rosen, I. G.

    1986-01-01

    Rayleigh-Ritz methods for the approximation of the natural modes for a class of vibration problems involving flexible beams with tip bodies using subspaces of piecewise polynomial spline functions are developed. An abstract operator-theoretic formulation of the eigenvalue problem is derived and spectral properties investigated. The existing theory for spline-based Rayleigh-Ritz methods applied to elliptic differential operators and the approximation properties of interpolatory splines are used to argue convergence and establish rates of convergence. An example and numerical results are discussed.

  19. Structural coloration of metallic surfaces with micro/nano-structures induced by elliptical vibration texturing

    Science.gov (United States)

    Yang, Yang; Pan, Yayue; Guo, Ping

    2017-04-01

    Creating orderly periodic micro/nano-structures on metallic surfaces, or structural coloration, for control of surface apparent color and optical reflectivity has been an exciting research topic over the years. The direct applications of structural coloration include color marking, display devices, and invisibility cloak. This paper presents an efficient method to colorize metallic surfaces with periodic micro/nano-gratings using elliptical vibration texturing. When the tool vibration is coupled with a constant cutting velocity, controlled periodic ripples can be generated due to the overlapping tool trajectory. These periodic ripples with a wavelength near visible spectrum can act as micro-gratings to introduce iridescent colors. The proposed technique also provides a flexible method for color marking of metallic surfaces with arbitrary patterns and images by precise control of the spacing distance and orientation of induced micro/nano-ripples. Theoretical analysis and experimental results are given to demonstrate structural coloration of metals by a direct mechanical machining technique.

  20. Vibrational properties of vacancy in bcc transition metals using ...

    Indian Academy of Sciences (India)

    quasi atom concept and density functional theory. Adams and Foiles [3] developed a model for bcc metal V with the Morse form as pair-potential between atoms, and this model was successfully applied to calculate many-body potentials. Johnson and Oh [4] have presented an analytic EAM model for the bcc metals in which ...

  1. Evaluation of the nanotube intrinsic resistance across the tip-carbon nanotube-metal substrate junction by Atomic Force Microscopy

    Science.gov (United States)

    2011-01-01

    Using an atomic force microscope (AFM) at a controlled contact force, we report the electrical signal response of multi-walled carbon nanotubes (MWCNTs) disposed on a golden thin film. In this investigation, we highlight first the theoretical calculation of the contact resistance between two types of conductive tips (metal-coated and doped diamond-coated), individual MWCNTs and golden substrate. We also propose a circuit analysis model to schematize the «tip-CNT-substrate» junction by means of a series-parallel resistance network. We estimate the contact resistance R of each contribution of the junction such as Rtip-CNT, RCNT-substrate and Rtip-substrate by using the Sharvin resistance model. Our final objective is thus to deduce the CNT intrinsic radial resistance taking into account the calculated electrical resistance values with the global resistance measured experimentally. An unwished electrochemical phenomenon at the tip apex has also been evidenced by performing measurements at different bias voltages with diamond tips. For negative tip-substrate bias, a systematic degradation in color and contrast of the electrical cartography occurs, consisting of an important and non-reversible increase of the measured resistance. This effect is attributed to the oxidation of some amorphous carbon areas scattered over the diamond layer covering the tip. For a direct polarization, the CNT and substrate surface can in turn be modified by an oxidation mechanism. PMID:21711904

  2. Lattice vibrational properties of transition metal carbides (TiC, ZrC ...

    Indian Academy of Sciences (India)

    [2], Singh and Gupta [3] and research papers [4–13]. The degeneracy of the opti- cal vibration frequencies of the zone center is common to all the transition metal carbides. The experimental information about these ionic semiconductors is pro- vided from the phonon dispersion data [14–17]. A survey of the literatures on the.

  3. Lattice vibrational properties of transition metal carbides (TiC, ZrC ...

    Indian Academy of Sciences (India)

    Lattice vibrational properties of transition metal carbides (TiC, ZrC and HfC) have been presented by including the effects of free-carrier doping and three-body interactions in the rigid shell model. The short-range overlap repulsion is operative up to the second neighbour ions. An excellent agreement has been obtained ...

  4. Electronic properties of precious-metal coated W tips in STM: Role of spin-orbit coupling

    Science.gov (United States)

    Yamashita, T.; Akiyama, T.; Nakamura, K.; Ito, T.; Rhim, S. H.; Freeman, A. J.

    2013-03-01

    Scanning tunneling microscopy (STM) has proved a versatile tool invigorating many physics at an atomic scale, where chemical identity and shape of the probe tip greatly affect resolution and sensitivity. There have been many efforts to functionalize STM tips: coating W tips with organic molecules and 3d transition metals, which facilitate the selective imaging with enhanced tunneling current. In this work, we model W(110) tips coated by precious metals such as Au, Ag, and Pt, in which large spin-orbit coupling significantly influences the electronic structure of the STM probe. Furthermore, we argue that this spin-orbit coupling can be used as a spin detecting STM probe without additional bias switching. The stability of the W(110) apex atom for each metal coating is also discussed. Supported at N. U. by the DOE (DE-FG02-05ER45372), and at Mie U. by the Young Researcher Overseas Visits Program for Vitalizing Brain Circulation (R2214) from the Japan Society for the Promotion of Science.

  5. Accelerated lifetime test of vibration isolator made of Metal Rubber material

    Science.gov (United States)

    Ao, Hongrui; Ma, Yong; Wang, Xianbiao; Chen, Jianye; Jiang, Hongyuan

    2017-01-01

    The Metal Rubber material (MR) is a kind of material with nonlinear damping characteristics for its application in the field of aerospace, petrochemical industry and so on. The study on the lifetime of MR material is impendent to its application in engineering. Based on the dynamic characteristic of MR, the accelerated lifetime experiments of vibration isolators made of MR working under random vibration load were conducted. The effects of structural parameters of MR components on the lifetime of isolators were studied and modelled with the fitting curves of degradation data. The lifetime prediction methods were proposed based on the models.

  6. Conformations and vibrational spectroscopy of metal-ion/polylalanine complexes

    NARCIS (Netherlands)

    Dunbar, R. C.; Steill, J. D.; Oomens, J.

    2010-01-01

    The thermochemistry and structures of complexes of dialanine and trialanine with a series of singly and doubly charged metal ions have been examined by spectroscopic and computational approaches. Complexes with Li+, K+, Cs+, Ca2+, Sr2+ and Ba2+ were formed by electrospray ionization, and studied by

  7. Water Oxidation Mechanisms of Metal Oxide Catalysts by Vibrational Spectroscopy of Transient Intermediates

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Miao [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Chemical Sciences Division; Univ. of California, Berkeley, CA (United States); Frei, Heinz [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Molecular Biophysics and Integrated Bioimaging Division; Univ. of California, Berkeley, CA (United States)

    2017-02-22

    Water oxidation is an essential reaction of an artificial photosystem for solar fuel generation because it provides electrons needed to reduce carbon dioxide or protons to a fuel. Earth-abundant metal oxides are among the most attractive catalytic materials for this reaction because of their robustness and scalability, but their efficiency poses a challenge. Knowledge of catalytic surface intermediates gained by vibrational spectroscopy under reaction conditions plays a key role in uncovering kinetic bottlenecks and provides a basis for catalyst design improvements. Recent dynamic infrared and Raman studies reveal the molecular identity of transient surface intermediates of water oxidation on metal oxides. In conclusion, combined with ultrafast infrared observations of how charges are delivered to active sites of the metal oxide catalyst and drive the multielectron reaction, spectroscopic advances are poised to play a key role in accelerating progress toward improved catalysts for artificial photosynthesis.

  8. Water Oxidation Mechanisms of Metal Oxide Catalysts by Vibrational Spectroscopy of Transient Intermediates

    Science.gov (United States)

    Zhang, Miao; Frei, Heinz

    2017-05-01

    Water oxidation is an essential reaction of an artificial photosystem for solar fuel generation because it provides electrons needed to reduce carbon dioxide or protons to a fuel. Earth-abundant metal oxides are among the most attractive catalytic materials for this reaction because of their robustness and scalability, but their efficiency poses a challenge. Knowledge of catalytic surface intermediates gained by vibrational spectroscopy under reaction conditions plays a key role in uncovering kinetic bottlenecks and provides a basis for catalyst design improvements. Recent dynamic infrared and Raman studies reveal the molecular identity of transient surface intermediates of water oxidation on metal oxides. Combined with ultrafast infrared observations of how charges are delivered to active sites of the metal oxide catalyst and drive the multielectron reaction, spectroscopic advances are poised to play a key role in accelerating progress toward improved catalysts for artificial photosynthesis.

  9. Tuning the vibration of a rotor with shape memory alloy metal rubber supports

    Science.gov (United States)

    Ma, Yanhong; Zhang, Qicheng; Zhang, Dayi; Scarpa, Fabrizio; Liu, Baolong; Hong, Jie

    2015-09-01

    The paper describes a novel smart rotor support damper with variable stiffness made with a new multifunctional material - the shape memory alloy metal rubber (SMA-MR). SMA-MR gives high load bearing capability (yield limit up to 100 MPa and stiffness exceeding 1e8 N/m), high damping (loss factor between 0.15 and 0.3) and variable stiffness (variation of 2.6 times between martensite and austenite phases). The SMA-MR has been used to replace a squeeze film damper and combined with an elastic support. The mechanical performance of the smart support damper has been investigated at room and high temperatures on a rotor test rig. The vibration tuning capabilities of the SMA-MR damper have been evaluated through FEM simulations and experimental tests. The study shows the feasibility of using the SMA-MR material for potential applications of active vibration control at different temperatures in rotordynamics systems.

  10. N-H···π hydrogen-bonding and large-amplitude tipping vibrations in jet-cooled pyrrole-benzene.

    Science.gov (United States)

    Pfaffen, Chantal; Infanger, Daniel; Ottiger, Philipp; Frey, Hans-Martin; Leutwyler, Samuel

    2011-08-21

    The N-H···π hydrogen bond is an important intermolecular interaction in many biological systems. We have investigated the infrared (IR) and ultraviolet (UV) spectra of the supersonic-jet cooled complex of pyrrole with benzene and benzene-d(6) (Pyr·Bz, Pyr·Bz-d(6)). DFT-D density functional, SCS-MP2 and SCS-CC2 calculations predict a T-shaped and (almost) C(s) symmetric structure with an N-H···π hydrogen bond to the benzene ring. The pyrrole is tipped by ω(S(0)) = ±13° relative to the surface normal of Bz. The N···ring distance is 3.13 Å. In the S(1) excited state, SCS-CC2 calculations predict an increased tipping angle ω(S(1)) = ±21°. The IR depletion spectra support the T-shaped geometry: The NH stretch is redshifted by -59 cm(-1), relative to the "free" NH stretch of pyrrole at 3531 cm(-1), indicating a moderately strong N-H···π interaction. The interaction is weaker than in the (Pyr)(2) dimer, where the NH donor shift is -87 cm(-1) [Dauster et al., Phys. Chem. Chem. Phys., 2008, 10, 2827]. The IR C-H stretch frequencies and intensities of the Bz subunit are very similar to those of the acceptor in the (Bz)(2) dimer, confirming that Bz acts as the acceptor. While the S(1)←S(0) electronic origin of Bz is forbidden and is not observable in the gas-phase, the UV spectrum of Pyr·Bz in the same region exhibits a weak 0 band that is red-shifted by 58 cm(-1) relative to that of Bz (38 086 cm(-1)). The origin appears due to symmetry-breaking of the π-electron system of Bz by the asymmetric pyrrole NH···π hydrogen bond. This contrasts with (Bz)(2), which does not exhibit a 0 band. The Bz moiety in Pyr·Bz exhibits a 6a band at 0 + 518 cm(-1) that is about 20× more intense than the origin band. The symmetry breaking by the NH···π hydrogen bond splits the degeneracy of the ν(6)(e(2g)) vibration, giving rise to 6a' and 6b' sub-bands that are spaced by ∼6 cm(-1). Both the 0 and 6 bands of Pyr·Bz carry a progression in the low

  11. Anisotropic excitation of surface plasmon polaritons on a metal film by a scattering-type scanning near-field microscope with a non-rotationally-symmetric probe tip

    Directory of Open Access Journals (Sweden)

    Walla Frederik

    2018-01-01

    Full Text Available We investigated the excitation of surface plasmon polaritons on gold films with the metallized probe tip of a scattering-type scanning near-field optical microscope (s-SNOM. The emission of the polaritons from the tip, illuminated by near-infrared laser radiation, was found to be anisotropic and not circularly symmetric as expected on the basis of literature data. We furthermore identified an additional excitation channel via light that was reflected off the tip and excited the plasmon polaritons at the edge of the metal film. Our results, while obtained for a non-rotationally-symmetric type of probe tip and thus specific for this situation, indicate that when an s-SNOM is employed for the investigation of plasmonic structures, the unintentional excitation of surface waves and anisotropic surface wave propagation must be considered in order to correctly interpret the signatures of plasmon polariton generation and propagation.

  12. Anisotropic excitation of surface plasmon polaritons on a metal film by a scattering-type scanning near-field microscope with a non-rotationally-symmetric probe tip

    Science.gov (United States)

    Walla, Frederik; Wiecha, Matthias M.; Mecklenbeck, Nicolas; Beldi, Sabri; Keilmann, Fritz; Thomson, Mark D.; Roskos, Hartmut G.

    2018-01-01

    We investigated the excitation of surface plasmon polaritons on gold films with the metallized probe tip of a scattering-type scanning near-field optical microscope (s-SNOM). The emission of the polaritons from the tip, illuminated by near-infrared laser radiation, was found to be anisotropic and not circularly symmetric as expected on the basis of literature data. We furthermore identified an additional excitation channel via light that was reflected off the tip and excited the plasmon polaritons at the edge of the metal film. Our results, while obtained for a non-rotationally-symmetric type of probe tip and thus specific for this situation, indicate that when an s-SNOM is employed for the investigation of plasmonic structures, the unintentional excitation of surface waves and anisotropic surface wave propagation must be considered in order to correctly interpret the signatures of plasmon polariton generation and propagation.

  13. 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.

  14. Detection of charge dynamics of a tetraphenylporphyrin particle using GaAs-based nanowire enhanced by particle-metal tip capacitive coupling

    Science.gov (United States)

    Okamoto, Shoma; Sato, Masaki; Sasaki, Kentaro; Kasai, Seiya

    2017-06-01

    We investigate a detection technique of charge dynamics of a molecular particle using a GaAs-based nanowire where the charge sensitivity is locally enhanced by particle-metal tip capacitive coupling. By equivalent circuit analysis, it was clarified that the nanowire channel potential becomes sensitive to the molecular particle on the nanowire when the particle is capacitively coupled with a metal tip. The concept was demonstrated using a GaAs-based nanowire with tetraphenylporphyrin (TPP) particles on its surface and a measurement system integrating an atomic force microscope (AFM) and a dynamic current measurement monitor/spectrum analyzer. When the metal tip was in contact with a TPP particle on the nanowire under an appropriate tip bias condition, random telegraph signal (RTS) noise was imposed on the nanowire current, suggesting the increase in sensitivity to the charge state of the particle by the metal tip contact. We discussed the origin of the RTS noise through analysis of the time constant of RTS noise, RTS amplitude, and noise spectrum.

  15. Influence of metal ions intercalation on the vibrational dynamics of water confined between MXene layers

    Science.gov (United States)

    Osti, Naresh C.; Naguib, Michael; Ganeshan, Karthik; Shin, Yun K.; Ostadhossein, Alireza; van Duin, Adri C. T.; Cheng, Yongqiang; Daemen, Luke L.; Gogotsi, Yury; Mamontov, Eugene; Kolesnikov, Alexander I.

    2017-11-01

    Two-dimensional (2D) carbides and nitrides of early transition metals (MXenes) combine high conductivity with hydrophilic surfaces, which make them promising for energy storage, electrocatalysis, and water desalination. The effects of intercalated metal ions on the vibrational states of water confined in Ti3C2Tx MXenes have been explored using inelastic neutron scattering (INS) and molecular-dynamics simulations to better understand the mechanisms that control MXenes' behavior in aqueous electrolytes, water purification, and other important applications. We observe an INS signal from water in all samples, pristine and with lithium, sodium, or potassium ions intercalated between the 2D Ti3C2Tx layers. However, only a small amount of water is found to reside in Ti3C2Tx intercalated with metal ions. Water in pristine Ti3C2Tx is more disordered, with bulklike characteristics, in contrast to intercalated Ti3C2Tx , where water is more ordered, irrespective of the metal ions used for intercalation. The ordering of the confined water increases with the ion size. This finding is further confirmed from molecular-dynamics simulation, which showed an increase in interference of water molecules with increasing ion size resulting in a concomitant decrease in water mobility, therefore providing guidance to tailor MXene properties for energy and environmental applications.

  16. Dielectrophoretic positioning of single nanoparticles on atomic force microscope tips for tip-enhanced Raman spectroscopy.

    Science.gov (United States)

    Leiterer, Christian; Deckert-Gaudig, Tanja; Singh, Prabha; Wirth, Janina; Deckert, Volker; Fritzsche, Wolfgang

    2015-05-01

    Tip-enhanced Raman spectroscopy, a combination of Raman spectroscopy and scanning probe microscopy, is a powerful technique to detect the vibrational fingerprint of molecules at the nanometer scale. A metal nanoparticle at the apex of an atomic force microscope tip leads to a large enhancement of the electromagnetic field when illuminated with an appropriate wavelength, resulting in an increased Raman signal. A controlled positioning of individual nanoparticles at the tip would improve the reproducibility of the probes and is quite demanding due to usually serial and labor-intensive approaches. In contrast to commonly used submicron manipulation techniques, dielectrophoresis allows a parallel and scalable production, and provides a novel approach toward reproducible and at the same time affordable tip-enhanced Raman spectroscopy tips. We demonstrate the successful positioning of an individual plasmonic nanoparticle on a commercial atomic force microscope tip by dielectrophoresis followed by experimental proof of the Raman signal enhancing capabilities of such tips. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Recovering metallic fractions from waste electrical and electronic equipment by a novel vibration system

    Energy Technology Data Exchange (ETDEWEB)

    Habib, Muddasar, E-mail: muddasar77@hotmail.com [Department of Chemical Engineering, University of Engineering and Technology, Peshawar (Pakistan); Miles, Nicholas J.; Hall, Philip [Faculty of Science and Engineering, University of Nottingham Ningbo China, Taikang East Road, Ningbo 315100 (China)

    2013-03-15

    Highlights: ► This work focuses on demonstrating a new scaled up technology to separate the metallic and non-metallic fractions of PCBs. ► PCBs comminuted to <1 mm in size resulted in metallic grade concentration of 95% in some of the recovered products. ► Good separation was observed at 40 mm particle bed height due to the formation of well-structured global convection currents. ► The work reported here contributes to the development of a new approach to dry, fine particle separation. - Abstract: The need to recover and recycle valuable resources from Waste Electrical and Electronic Equipment (WEEE) is of growing importance as increasing amounts are generated due to shorter product life cycles, market expansions, new product developments and, higher consumption and production rates. The European Commission (EC) directive, 2002/96/EC, on WEEE became law in UK in January 2007 setting targets to recover up to 80% of all WEEE generated. Printed Wire Board (PWB) and/or Printed Circuit Board (PCB) is an important component of WEEE with an ever increasing tonnage being generated. However, the lack of an accurate estimate for PCB production, future supply and uncertain demands of its recycled materials in international markets has provided the motivation to explore different approaches to recycle PCBs. The work contained in this paper focuses on a novel, dry separation methodology in which vertical vibration is used to separate the metallic and non-metallic fractions of PCBs. When PCBs were comminuted to less than 1 mm in size, metallic grades as high as 95% (measured by heavy liquid analysis) could be achieved in the recovered products.

  18. Vibrational spectroscopy and analysis of pseudo-tetrahedral complexes with metal imido bonds.

    Science.gov (United States)

    Mehn, Mark P; Brown, Steven D; Jenkins, David M; Peters, Jonas C; Que, Lawrence

    2006-09-04

    A number of assignments have been previously posited for the metal-nitrogen stretch (nu(M-NR)), the N-R stretch (nu(MN-R)), and possible ligand deformation modes associated with terminally bound imides. Here we examine mononuclear iron(III) and cobalt(III) imido complexes of the monoanionic tridentate ligand [PhBP3] ([PhBP3] = [PhB(CH2PPh2)3]-) to clarify the vibrational features for these trivalent metal imides. We report the structures of [PhBP3]FeNtBu and [PhBP3]CoNtBu. Pseudo-tetrahedral metal imides of these types exhibit short bond lengths (ca. 1.65 A) and nearly linear angles about the M-N-C linkages, indicative of multiple bond character. Furthermore, these compounds give rise to intense, low-energy visible absorptions. Both the position and the intensity of the optical bands in the [PhBP3]MNR complexes depend on whether the substituent is an alkyl or aryl group. Excitation into the low-energy bands of [PhBP3]FeNtBu gives rise to two Raman features at 1104 and 1233 cm(-1), both of which are sensitive to 15N and 2H labeling. The isotope labeling suggests the 1104 cm(-1) mode has the greatest Fe-N stretching character, while the 1233 cm(-1) mode is affected to a lesser extent by (15)N substitution. The spectra of the deuterium-labeled imides further support this assertion. The data demonstrate that the observed peaks are not simple diatomic stretching modes but are extensively coupled to the vibrations of the ancillary organic group. Therefore, describing these complexes as simple diatomic or even triatomic oscillators is an oversimplification. Analogous studies of the corresponding cobalt(III) complex lead to a similar set of isotopically sensitive resonances at 1103 and 1238 cm(-1), corroborating the assignments made in the iron imides. Very minimal changes in the vibrational frequencies are observed upon replacement of cobalt(III) for iron(III), suggesting similar force constants for the two compounds. This is consistent with the previously proposed

  19. An Evaluation of the use of Laser-Vibration Melting to Increase the Surface Roughness of Metal Objects

    Directory of Open Access Journals (Sweden)

    Grabas B.

    2015-04-01

    Full Text Available This paper presents preliminary, experimental results of a new, hybrid method of increasing the surface roughness of metal objects. In this new approach, metal objects are melted with a mobile laser beam while they are being rotated. A vibration generator provides circular vibrations with an amplitude of 3 mm, and the vibration plane is perpendicular to the moving laser beam. The melting tests were performed using flat carbon steel samples at a predetermined frequency of circular vibrations. The effects of laser power and laser beam scanning velocity on the melted shapes were studied. All laser melting procedures were performed at a vibration frequency of 105 Hz. The melted samples were subjected to microscopic evaluation and the Ra parameter, which characterises mean roughness, was measured using a profilometer. Melting metal samples with physically smooth surfaces (Ra = 0.21 µm resulted in surface structures of varied roughness values, with Ra ranging from 5 µm to approximately 58 µm. The studies were undertaken to employ this technology for the purpose of passive heat exchange intensification of heating surfaces in practical applications.

  20. Influence of Electrolyte Modulus on the Local Current Density at a Dendrite Tip on a Lithium Metal Electrode

    Energy Technology Data Exchange (ETDEWEB)

    Harry, KJ; Higa, K; Srinivasan, V; Balsara, NP

    2016-08-10

    Understanding and controlling the electrochemical deposition of lithium is imperative for the safe use of rechargeable batteries with a lithium metal anode. Solid block copolymer electrolyte membranes are known to enhance the stability of lithium metal anodes by mechanically suppressing the formation of lithium protrusions during battery charging. Time-resolved hard X-ray microtomography was used to monitor the internal structure of a symmetric lithium-polymer cell during galvanostatic polarization. The microtomography images were used to determine the local rate of lithium deposition, i.e. local current density, in the vicinity of a lithium globule growing through the electrolyte. Measurements of electrolyte displacement enabled estimation of local stresses in the electrolyte. At early times, the current density was maximized at the globule tip, as expected from simple current distribution arguments. At later times, the current density was maximized at the globule perimeter. We show that this phenomenon is related to the local stress fields that arise as the electrolyte is deformed. The local current density, normalized for the radius of curvature, decreases with increasing compressive stresses at the lithium-polymer interface. To our knowledge, our study provides the first direct measurement showing the influence of local mechanical stresses on the deposition kinetics at lithium metal electrodes.

  1. Towards quantitative off-axis electron holographic mapping of the electric field around the tip of a sharp biased metallic needle

    Energy Technology Data Exchange (ETDEWEB)

    Beleggia, M. [Center for Electron Nanoscopy, Technical University of Denmark, Kongens Lyngby (Denmark); Helmholtz-Zentrum Berlin für Materialien und Energie, Berlin (Germany); Kasama, T. [Center for Electron Nanoscopy, Technical University of Denmark, Kongens Lyngby (Denmark); Larson, D. J.; Kelly, T. F. [CAMECA Instruments, Inc., Madison, Wisconsin 53711 (United States); Dunin-Borkowski, R. E. [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungzentrum Jülich, Jülich (Germany); Pozzi, G. [Department of Physics and Astronomy, University of Bologna, Bologna (Italy)

    2014-07-14

    We apply off-axis electron holography and Lorentz microscopy in the transmission electron microscope to map the electric field generated by a sharp biased metallic tip. A combination of experimental data and modelling provides quantitative information about the potential and the field around the tip. Close to the tip apex, we measure a maximum field intensity of 82 MV/m, corresponding to a field k factor of 2.5, in excellent agreement with theory. In order to verify the validity of the measurements, we use the inferred charge density distribution in the tip region to generate simulated phase maps and Fresnel (out-of-focus) images for comparison with experimental measurements. While the overall agreement is excellent, the simulations also highlight the presence of an unexpected astigmatic contribution to the intensity in a highly defocused Fresnel image, which is thought to result from the geometry of the applied field.

  2. Towards quantitative off-axis electron holographic mapping of the electric field around the tip of a sharp biased metallic needle

    DEFF Research Database (Denmark)

    Beleggia, Marco; Kasama, Takeshi; Larson, D. J.

    2014-01-01

    the tip. Close to the tip apex, we measure a maximum field intensity of 82 MV/m, corresponding to a field k factor of 2.5, in excellent agreement with theory. In order to verify the validity of the measurements, we use the inferred charge density distribution in the tip region to generate simulated phase......We apply off-axis electron holography and Lorentz microscopy in the transmission electron microscope to map the electric field generated by a sharp biased metallic tip. A combination of experimental data and modelling provides quantitative information about the potential and the field around...... maps and Fresnel (out-of-focus) images for comparison with experimental measurements. While the overall agreement is excellent, the simulations also highlight the presence of an unexpected astigmatic contribution to the intensity in a highly defocused Fresnel image, which is thought to result from...

  3. Ab initio calculation of H interactions with defects in fcc metals : crack tip dislocations and vacancies

    OpenAIRE

    Wang, Yu

    2014-01-01

    In many technological applications of structured metallic alloys, hydrogen embrittlement (HE) is a major concern as it can penetrate in most metals, degrade their properties and lead to premature failures. Despite numerous efforts in the past decades during which many microscopic mechanisms were proposed, a clear understanding of H embrittlement mechanisms has not been achieved yet. Since HE processes occur on an atomic-scale, the exact mechanisms leading to HE are not easily identified exper...

  4. Recovering metallic fractions from waste electrical and electronic equipment by a novel vibration system.

    Science.gov (United States)

    Habib, Muddasar; Miles, Nicholas J; Hall, Philip

    2013-03-01

    The need to recover and recycle valuable resources from Waste Electrical and Electronic Equipment (WEEE) is of growing importance as increasing amounts are generated due to shorter product life cycles, market expansions, new product developments and, higher consumption and production rates. The European Commission (EC) directive, 2002/96/EC, on WEEE became law in UK in January 2007 setting targets to recover up to 80% of all WEEE generated. Printed Wire Board (PWB) and/or Printed Circuit Board (PCB) is an important component of WEEE with an ever increasing tonnage being generated. However, the lack of an accurate estimate for PCB production, future supply and uncertain demands of its recycled materials in international markets has provided the motivation to explore different approaches to recycle PCBs. The work contained in this paper focuses on a novel, dry separation methodology in which vertical vibration is used to separate the metallic and non-metallic fractions of PCBs. When PCBs were comminuted to less than 1mm in size, metallic grades as high as 95% (measured by heavy liquid analysis) could be achieved in the recovered products. Copyright © 2012 Elsevier Ltd. All rights reserved.

  5. Vibrational and electronic circular dichroism study of bile pigments: complexes of bilirubin and biliverdin with metals.

    Science.gov (United States)

    Goncharova, Iryna; Urbanová, Marie

    2009-09-01

    Complexation of bilirubin (BR) and biliverdin (BV) with biogenic and toxic metals (Mn, Cu, Cd, Co, Fe, Ni, Zn, and Ag) has been studied by means of electronic circular dichroism (ECD) and vibrational circular dichroism (VCD). Poly-L-lysine and beta-cyclodextrin in water were chosen as matrices capable of recognizing the single stereoconformer of the pigments with defined M-helicity. Such systems allow structural changes caused by complexation of pigments with metals in aqueous solution at pH 10-11 to be followed using chiroptical methods, which are intrinsically sensitive to spatial structure. These and other spectroscopic techniques have revealed that BV and BR form monomeric complexes with Cd, Cu, and Zn and dimeric complexes with Mn. The stabilities of the complexes with Fe, Ni, Co, and Ag are remarkably lower. The sign of the ECD and VCD patterns of the complexed BV does not change for the chelates of any of the studied metals other than Zn, this exception being interpreted in terms of manifestation of the opposite helicity of BV in its chelate with Zn. In the case of BR, the observed inversion of ECD signal after complexation, together with the analysis of VCD spectra, reveals that a flattening of the molecule takes place, i.e., an increase in the angle between the pyrrinone chromophores without an inversion of helicity. This chiral stereoselectivity, which is very specific in the case of the Zn chelates, is discussed in connection with the specific inhibition of Zn-required enzymes by bile pigments.

  6. Subcooled boiling-induced vibration of a heater rod located between two metallic walls

    Energy Technology Data Exchange (ETDEWEB)

    Takano, Kenji, E-mail: kenji_takano@mhi.co.jp; Hashimoto, Yusuke; Kunugi, Tomoaki; Yokomine, Takehiko; Kawara, Zensaku

    2016-11-15

    Highlights: • A heating structure in water vibrates itself due to subcooled boiling (SBIV). • Experiments with a heater rod located between two metallic walls were conducted. • Large bubbles growing in 1 mm-gap distance with each wall influenced on the SBIV. • Frequency of large bubble generation corresponded to acceleration of the heater rod. • Acceleration of the heater rod in the direction towards each wall was encouraged. - Abstract: The phenomenon that a heating structure vibrates itself due to the behavior of vapor bubbles generated under subcooled boiling has been known as “Subcooled Boiling-induced Vibration (SBIV)”. As one of such a heating structure, fuel assemblies for Boiling Water Reactors (BWR) are utilized in subcooled boiling of water, and those for Pressurized Water Reactors (PWR) may face unexpected subcooled boiling conditions in case of sudden drop of the system pressure or loss of water flow, though they are utilized in single phase of water under normal operating conditions. As studies on SBIV, some researchers have conducted demonstrative experiments with a partial array of fuel rods simulating the actual BWR fuel assembly in a flow test loop, which showed no significant influences of the SBIV to degrade the integrity of the fuel rods. In addition, in order to investigate the fundamental phenomenon of the SBIV, pool boiling experiments of the SBIV on a single heater rod were performed in other studies with a simplified apparatus of a water tank in laboratory size under atmospheric pressure. In the experiments, behavior of bubbles generated under various degree of subcooling were observed, and the acceleration of the SBIV of the heater rod was measured. The present study, as a series of the above experiments for the fundamental phenomenon of the SBIV, the two thin walls made of stainless steel were installed in parallel to interleave the heater rod with the gap distance of 1 mm or 3 mm to each of the two walls, which was expected

  7. Tipping Point

    Medline Plus

    Full Text Available ... OnSafety CPSC Stands for Safety The Tipping Point Home > 60 Seconds of Safety (Videos) > The Tipping Point The Tipping Point by CPSC Blogger September 22, 2009 appliance child Childproofing CPSC danger death electrical fall furniture ...

  8. Influence of vegetable based cutting fluids on cutting force and vibration signature during milling of aluminium metal matrix composites

    Directory of Open Access Journals (Sweden)

    S. Shankar

    2017-03-01

    Full Text Available Due to the environmental and health issues, there is an enormous requirement for developing the novel cutting fluids (CFs. The vegetable based cutting fluid (VBCFs doesn’t affect the environment, diminish the harmful effects to the operator and also enhance the machining performances such as surface roughness, tool life, minimum vibration and cutting forces. In this work, the performances of four different VBCFs like palm, coconut, sunflower, soya bean oils, and a commercial type of CFs were considered to analyze the influence of cutting fluids while measuring the cutting force and vibration signatures during milling of 7075–T6 hybrid aluminium metal matrix composite with carbide insert tool. The experiments were conducted in CNC L-MILL 55 vertical machining center, with milling tool dynamometer to measure the cutting force and a tri-axial accelerometer to measure the vibration signals. The flow rate of the VBCFs were maintained at a constant rate and the results were compared with a commercial cutting fluid. The obtained result shows that palm oil suits better than the other vegetable based cutting fluids in terms of minimum cutting force requirement and minimum vibration. Also, the experimental result shows that the cutting fluid was one of the important parameter needs to be considered which influences the cutting force and vibration signals.

  9. MICROSTRUCTURAL STUDY OF FAILURE PHENOMENA IN WC 94%-Co 6% HARD METAL ALLOY TIPS OF RADIAL PICKS

    Directory of Open Access Journals (Sweden)

    Sakuntala Nahak

    2017-03-01

    Full Text Available An excellent combination of hardness, strength, stiffness and high melting point has proved the WC-Co as an ideal material for tools which are used for metal cutting, coal mining, oil drilling, etc. The ongoing research in WC-Co is focussed on enhancing its wear resistant properties as much as possible. For the purpose, many attempts have been made to study the tribological behaviour of WC-Co for a long time. Researchers have used various grades of WC-Co in different working environment and accordingly they have characterized the wear phenomena involved in it. In this direction of research, the present paper makes an attempt to understand various wear behaviours in WC 94%-Co 6% hard metal alloy. WC-Co was used as a tip of the coal cutting tool, named, radial pick. Two radial picks have been taken for critical analysis through field emission scanning electron microscopy (FESEM attached with energy dispersive X-ray spectroscopy (EDS. In this work, the failure behaviours in the tools have been divided into five categories: (1 Abrasion on individual grain; (2 Corrosion in carbide grains; (3 Fragmentation and removal of WC grains; (4 Pores in WC grains; and (5 Coal and rock embedding. The most possible reasons behind each failure phenomenon have been explained comprehensively with the help of high resolution microscopic images. However, it is usually observed that, initially, the tool gets minor cracks due to sudden impact. These cracks provide a path to the rock and coal particles to get entrenched inside the microstructure of cemented carbide. Finally, the intermixed external elements degrade the binder content (i.e. cobalt and the tool becomes useless.

  10. Submolecular resolution in scanning probe images of Sn-phthalocyanines on Cu(1 0 0) using metal tips

    Science.gov (United States)

    Buchmann, Kristof; Hauptmann, Nadine; Foster, Adam S.; Berndt, Richard

    2017-10-01

    Single Sn-phthalocyanine (SnPc) molecules adsorb on Cu(1 0 0) with the Sn ion above (Sn-up) or below (Sn-down) the molecular plane. Here we use a combination of atomic force microscopy (AFM), scanning tunnelling microscopy (STM) and first principles calculations to understand the adsorption configuration and origin of observed contrast of molecules in the Sn-down state. AFM with metallic tips images the pyrrole nitrogen atoms in these molecules as attractive features while STM reveals a chirality of the electronic structure of the molecules close to the Fermi level E_F, which is not observed in AFM. Using density functional theory calculations, the origin of the submolecular contrast is analysed and, while the electrostatic forces turn out to be negligible, the van der Waals interaction between the phenyl rings of SnPc and the substrate deform the molecule, push the pyrrole nitrogen atoms away from the substrate and thus induce the observed submolecular contrast. Simulated STM images reproduce the chirality of the electronic structure near E_F.

  11. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

    Medline Plus

    Full Text Available ... the hepatic vein in the liver. A small metal device called a stent is placed to keep ... open by the placement of a small, tubular metal device commonly called a stent . During a TIPS ...

  12. A unifying model for non-adiabatic coupling at metallic surfaces beyond the local harmonic approximation: from vibrational relaxation to scanning tunneling microscopy.

    Science.gov (United States)

    Tremblay, Jean Christophe

    2013-06-28

    A model for treating excitation and relaxation of adsorbates at metallic surfaces induced by non-adiabatic coupling is developed. The derivation is based on the concept of resonant electron transfer, where the adsorbate serves as a molecular bridge for the inelastic transition between an electron source and a sink. In this picture, energy relaxation and scanning tunneling microscopy (STM) at metallic surfaces are treated on an equal footing as a quasi-thermal process. The model goes beyond the local harmonic approximation and allows for an unbiased description of floppy systems with multiple potential wells. Further, the limitation of the product ansatz for the vibronic wave function to include the position-dependence of the non-adiabatic couplings is avoided by explicitly enforcing detailed balance. The theory is applied to the excitation of hydrogen on palladium, which has multiple local potential minima connected by low energy barriers. The main aspects investigated are the lifetimes of adsorbate vibrations in different adsorption sites, as well as the dependence of the excitation, response, and transfer rates on an applied potential bias. The excitation and relaxation simulations reveal intricate population dynamics that depart significantly from the simplistic tunneling model in a truncated harmonic potential. In particular, the population decay from an initially occupied local minimum induced by the contact with an STM tip is found to be better described by a double exponential. The two rates are interpreted as a response to the system perturbation and a transfer rate following the perturbation. The transfer rate is found to obey a power law, as was the case in previous experimental and theoretical work.

  13. Dipole active vibrations and dipole moments of N2 and O2 physisorbed on a metal surface

    Science.gov (United States)

    Gustafsson, K.; Andersson, S.

    2006-07-01

    We have, in infrared reflection absorption measurements, observed narrow dipole active absorption lines associated with the fundamental internal vibrational transitions of N2 and O2 physisorbed at 30K on the chemically inert Pt(111)(1×1)H surface. Such transitions are forbidden for free homonuclear molecules and become dipole active at a metal surface due to polarization induced surface dipole moments. The measurements show that the internal stretch vibration frequencies are lowered by 7-8cm-1 relative to the gas phase values. The measured static and dynamic dipole moments are in the ranges of 0.06-0.07 and 0.001-0.002D, respectively. We find that good estimates of the induced dynamic as well as the static dipole moments can in general be obtained from a van der Waals model but that the ratios of the measured static and dynamic moments indicates a need for a refinement of the dipole moment function.

  14. Tipping Point

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    Full Text Available ... and furniture, appliance and tv tip-overs. The force of a large television falling from tipping furniture ... 50 lb. TV falls with about the same force as child falling from the third story of ...

  15. Tipping Point

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    Full Text Available ... death electrical fall furniture head injury product safety television tipover tv Watch the video in Adobe Flash ... tv tip-overs. The force of a large television falling from tipping furniture can be staggering. A ...

  16. Vibrationally mediated control of single-electron transmission in weakly coupled molecule-metal junctions

    DEFF Research Database (Denmark)

    Olsen, Thomas; Schiøtz, Jakob

    2010-01-01

    We propose a mechanism which allows one to control the transmission of single electrons through a molecular junction. The principle utilizes the emergence of transmission sidebands when molecular vibrational modes are coupled to the electronic state mediating the transmission. We will show that i....... As an example we perform a density-functional theory analysis of a benzene molecule between two Au(111) contacts and show that exciting a particular vibrational mode can give rise to transmission of a single electron....

  17. Adsorption-induced symmetry reduction of metal-phthalocyanines studied by vibrational spectroscopy

    Science.gov (United States)

    Sforzini, J.; Bocquet, F. C.; Tautz, F. S.

    2017-10-01

    We investigate the vibrational properties of Pt- and Pd-phthalocyanine (PtPc and PdPc) molecules on Ag(111) with high-resolution electron energy loss spectroscopy (HREELS). In the monolayer regime, both molecules exhibit long-range order. The vibrational spectra prove a flat adsorption geometry. The redshift of specific vibrational modes suggests a moderate interaction of the molecules with the substrate. The presence of asymmetric vibrational peaks indicates an interfacial dynamical charge transfer (IDCT). The molecular orbital that is involved in IDCT is the former Eg lowest unoccupied molecular orbital (LUMO) of the molecules that becomes partially occupied upon adsorption. A group-theoretical analysis of the IDCT modes, based on calculated vibrational frequencies and line shape fits, provides proof for the reduction of the symmetry of the molecule-substrate complex from fourfold D4 h to C2 v(σv) , Cs(σv) , or C2 and the ensuing lifting of the degeneracy of the former LUMO of the molecule. The vibration-based analysis of orbital degeneracies, as carried out here for PtPc/Ag(111) and PdPc/Ag(111), is particularly useful whenever the presence of multiple molecular in-plane orientations at the interface makes the analysis of orbital degeneracies with angle-resolved photoemission spectroscopy difficult.

  18. Tipping Point

    Medline Plus

    Full Text Available ... en español Blog About OnSafety CPSC Stands for Safety The Tipping Point Home > 60 Seconds of Safety (Videos) > The Tipping Point The Tipping Point by ... danger death electrical fall furniture head injury product safety television tipover tv Watch the video in Adobe ...

  19. Layer-number dependent high-frequency vibration modes in few-layer transition metal dichalcogenides induced by interlayer couplings

    Science.gov (United States)

    Tan, Qing-Hai; Zhang, Xin; Luo, Xiang-Dong; Zhang, Jun; Tan, Ping-Heng

    2017-03-01

    Two-dimensional transition metal dichalcogenides (TMDs) have attracted extensive attention due to their many novel properties. The atoms within each layer in two-dimensional TMDs are joined together by covalent bonds, while van der Waals interactions combine the layers together. This makes its lattice dynamics layer-number dependent. The evolutions of ultralow frequency ( 50 cm-1) vibration modes in few-layer TMDs and demonstrate how the interlayer coupling leads to the splitting of high-frequency vibration modes, known as Davydov splitting. Such Davydov splitting can be well described by a van der Waals model, which directly links the splitting with the interlayer coupling. Our review expands the understanding on the effect of interlayer coupling on the high-frequency vibration modes in TMDs and other two-dimensional materials. Project supported by the National Basic Research Program of China (No. 2016YFA0301200), the National Natural Science Foundation of China (Nos. 11225421, 11474277, 11434010, 61474067, 11604326, 11574305 and 51527901), and the National Young 1000 Talent Plan of China.

  20. ROLE OF DISCRETE NATURE OF CHIP FORMATION AND NATURAL VIBRATIONS OF SYSTEM COMPONENTS IN CHATTER FORMATION DURING METAL CUTTING

    Directory of Open Access Journals (Sweden)

    A. K. M. Nurulamin

    2010-05-01

    Full Text Available In the present work a review of the existing theories of chatter formation has been conducted and the weaknesses of the most widely accepted ‘Regenerative Chatter theory’ in explaining various phenomena related to chatter formation have been identified. An attempt has been made in this work to determine the common causes of chatter formation in different metal cutting operations, namely, turning, thread cutting and end milling conducted on plain carbon steel AISI 1040. Experimental investigations have been conducted during the above types of machining processes to identify the marks of instability and chatter on the formed chips. It has been identified that in all the three machining operations the chips formed show a common type of discreteness in the form of secondary saw teeth, which appear at the free edge of the chip. Mechanism of formation of these teeth has been studied and the frequencies of their formation have been determined for different cutting conditions. Apart from the secondary saw teeth primary saw teeth have also been identified at the main section of the chip and their frequencies were also determined. At the same time the natural vibrations of the main system components have been identified and the acceleration amplitudes at the prominent natural frequencies during actual machining were recoded using a dedicated vibration monitoring system. The frequencies of secondary chip serration and the natural frequencies of the system components were plotted against cutting speed. Acceleration amplitudes at the prominent natural frequencies were also plotted separately against cutting force. Based on comparison and analysis of these two frequency and amplitude graphs it was concluded that chatter (vibration with relatively high amplitude appears in the system when the frequency of secondary saw teeth approaches values equal to half or integer multiple of a prominent natural frequency of the system resulting in resonance. In the

  1. Vibrational Stark Effect to Probe the Electric-Double Layer of the Ionic Liquid-Metal Electrodes

    Science.gov (United States)

    Garcia Rey, Natalia; Moore, Alexander Knight; Toyouchi, Shuichi; Dlott, Dana

    2017-06-01

    Vibrational sum frequency generation (VSFG) spectroscopy is used to study the effect of room temperature ionic liquids (RTILs) in situ at the electrical double layer (EDL). RTILs have been recognized as electrolytes without solvent for applications in batteries, supercapacitors and electrodeposition^{1}. The molecular response of the RTIL in the EDL affects the performance of these devices. We use the vibrational Stark effect on CO as a probe to detect the changes in the electric field affected by the RTIL across the EDL on metal electrodes. The Stark effect is a shift in the frequency in response to an externally applied electric field and also influenced by the surrounding electrolyte and electrode^{2}. The CO Stark shift is monitored by the CO-VSFG spectra on Pt or Ag in a range of different imidazolium-based RTILs electrolytes, where their composition is tuned by exchanging the anion, the cation or the imidazolium functional group. We study the free induction decay (FID)^{3} of the CO to monitor how the RTIL structure and composition affect the vibrational relaxation of the CO. Combining the CO vibrational Stark effect and the FID allow us to understand how the RTIL electrochemical response, molecular orientation response and collective relaxation affect the potential drop of the electric field across the EDL, and, in turn, how determines the electrical capacitance or reactivity of the electrolyte/electrode interface. ^{1}Fedorov, M. V.; Kornyshev, A. A., Ionic Liquids at Electrified Interfaces. Chem. Rev. 2014, 114, 2978-3036. ^{2} (a) Lambert, D. K., Vibrational Stark Effect of Adsorbates at Electrochemical Interfaces. Electrochim. Acta 1996, 41, 623-630. (b) Oklejas, V.; Sjostrom, C.; Harris, J. M., SERS Detection of the Vibrational Stark Effect from Nitrile-Terminated SAMs to Probe Electric Fields in the Diffuse Double-Layer. J. Am. Chem. Soc. 2002, 124, 2408-2409. ^{3}Symonds, J. P. R.; Arnolds, H.; Zhang, V. L.; Fukutani, K.; King, D. A

  2. Vibrational spectroscopy in the electron microscope.

    Science.gov (United States)

    Krivanek, Ondrej L; Lovejoy, Tracy C; Dellby, Niklas; Aoki, Toshihiro; Carpenter, R W; Rez, Peter; Soignard, Emmanuel; Zhu, Jiangtao; Batson, Philip E; Lagos, Maureen J; Egerton, Ray F; Crozier, Peter A

    2014-10-09

    Vibrational spectroscopies using infrared radiation, Raman scattering, neutrons, low-energy electrons and inelastic electron tunnelling are powerful techniques that can analyse bonding arrangements, identify chemical compounds and probe many other important properties of materials. The spatial resolution of these spectroscopies is typically one micrometre or more, although it can reach a few tens of nanometres or even a few ångströms when enhanced by the presence of a sharp metallic tip. If vibrational spectroscopy could be combined with the spatial resolution and flexibility of the transmission electron microscope, it would open up the study of vibrational modes in many different types of nanostructures. Unfortunately, the energy resolution of electron energy loss spectroscopy performed in the electron microscope has until now been too poor to allow such a combination. Recent developments that have improved the attainable energy resolution of electron energy loss spectroscopy in a scanning transmission electron microscope to around ten millielectronvolts now allow vibrational spectroscopy to be carried out in the electron microscope. Here we describe the innovations responsible for the progress, and present examples of applications in inorganic and organic materials, including the detection of hydrogen. We also demonstrate that the vibrational signal has both high- and low-spatial-resolution components, that the first component can be used to map vibrational features at nanometre-level resolution, and that the second component can be used for analysis carried out with the beam positioned just outside the sample--that is, for 'aloof' spectroscopy that largely avoids radiation damage.

  3. Investigating vibrational anharmonic couplings in cyanide-bridged transition metal mixed valence complexes using two-dimensional infrared spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Slenkamp, Karla M.; Lynch, Michael S.; Van Kuiken, Benjamin E.; Brookes, Jennifer F.; Bannan, Caitlin C.; Daifuku, Stephanie L.; Khalil, Munira, E-mail: mkhalil@chem.washington.edu [Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195 (United States)

    2014-02-28

    Using polarization-selective two-dimensional infrared (2D IR) spectroscopy, we measure anharmonic couplings and angles between the transition dipole moments of the four cyanide stretching (ν{sub CN}) vibrations found in [(NH{sub 3}){sub 5}Ru{sup III}NCFe{sup II}(CN){sub 5}]{sup −} (FeRu) dissolved in D{sub 2}O and formamide and [(NC){sub 5}Fe{sup II}CNPt{sup IV}(NH{sub 3}){sub 4}NCFe{sup II}(CN){sub 5}]{sup 4−} (FePtFe) dissolved in D{sub 2}O. These cyanide-bridged transition metal complexes serve as model systems for studying the role of high frequency vibrational modes in ultrafast photoinduced charge transfer reactions. Here, we focus on the spectroscopy of the ν{sub CN} modes in the electronic ground state. The FTIR spectra of the ν{sub CN} modes of the bimetallic and trimetallic systems are strikingly different in terms of frequencies, amplitudes, and lineshapes. The experimental 2D IR spectra of FeRu and FePtFe and their fits reveal a set of weakly coupled anharmonic ν{sub CN} modes. The vibrational mode anharmonicities of the individual ν{sub CN} modes range from 14 to 28 cm{sup −1}. The mixed-mode anharmonicities range from 2 to 14 cm{sup −1}. In general, the bridging ν{sub CN} mode is most weakly coupled to the radial ν{sub CN} mode, which involves the terminal CN ligands. Measurement of the relative transition dipole moments of the four ν{sub CN} modes reveal that the FeRu molecule is almost linear in solution when dissolved in formamide, but it assumes a bent geometry when dissolved in D{sub 2}O. The ν{sub CN} modes are modelled as bilinearly coupled anharmonic oscillators with an average coupling constant of 6 cm{sup −1}. This study elucidates the role of the solvent in modulating the molecular geometry and the anharmonic vibrational couplings between the ν{sub CN} modes in cyanide-bridged transition metal mixed valence complexes.

  4. Shoe-mounted vibration energy harvester of PZT piezoelectric thin films on metal foils

    Science.gov (United States)

    Nishi, T.; Ito, T.; Hida, H.; Kanno, I.

    2016-11-01

    This paper describes shoe-mounted piezoelectric vibration energy harvesters (PVEHs). The PVEHs were fabricated from Pb(ZrTi)O3 (PZT) thin films which were directly deposited onto Pt/Ti-coated stainless steel foil by rf-magnetron sputtering. We experimentally and theoretically evaluated impulse responses of the PVEHs by applying a simple impulse input on the energy harvesters, typical damped free vibration behaviour was clearly observed, and the output signal was in good agreement with the theoretical value. We measured the output power by applying the impulse input with an optimal load resistance of 33.9 kΩ. The maximum output power was approximately 20 μW, which correspond with the calculated value based on theoretical equation. From these results, the theoretical equation we derived might be helpful for design purposes of the shoe-mounted PVEHs.

  5. CPAP Tips

    Medline Plus

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  6. Technology Tips

    Science.gov (United States)

    Mathematics Teacher, 2004

    2004-01-01

    Some inexpensive or free ways that enable to capture and use images in work are mentioned. The first tip demonstrates the methods of using some of the built-in capabilities of the Macintosh and Windows-based PC operating systems, and the second tip describes methods to capture and create images using SnagIt.

  7. Tipping Point

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    Full Text Available ... OnSafety CPSC Stands for Safety The Tipping Point Home > 60 Seconds of Safety (Videos) > The Tipping Point ... 24 hours a day. For young children whose home is a playground, it’s the best way to ...

  8. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

    Medline Plus

    Full Text Available ... portal vein to the hepatic vein in the liver. A small metal device called a stent is ... bowel back to the heart while avoiding the liver. TIPS may successfully reduce internal bleeding in the ...

  9. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

    Medline Plus

    Full Text Available ... liver. The shunt is kept open by the placement of a small, tubular metal device commonly called ... of the condition. To help plan for the placement of the TIPS stent, a contrast material will ...

  10. Evaluation of NaCl Effect on Vibration-Delaminated Metal-Polymer Composites by Improved Micro-Raman Methodology

    Directory of Open Access Journals (Sweden)

    E. Zumelzu

    2013-01-01

    Full Text Available Polyethylene terephthalate (PET is a polymer coating that protects the electrolytic chromium coated steel (ECCS against aggressive electrolytes like NaCl. It is widely accepted by manufacturers that NaCl has no effect on the PET coating, which is inert. However, we showed that there are some effects at the structural level, caused by vibrations, and facilitated by defects on the layers. The vibrations occurring during the transportation of food containers produce delaminations at given points of the metal-polymer interface, known as antinodes, which in turn may produce PET degradation affecting food quality. The former can be determined by electrochemical measurements, and the changes in composition or structural order can be characterized by Raman. The present work applied this latter technique in experimental samples of PET-coated ECCS sheets by performing perpendicular and parallel analyses to the surface, and determined that it constitutes a new potential methodology to determine the behavior of the composite under the above conditions. The results demonstrated that the delamination areas on the PET facilitated polymer degradation by the electrolyte. Moreover, the Raman characterization evidenced the presence of multilayers and crystalline orderings, which limited its functionality as a protective coating.

  11. Synthesis, vibrational spectrometry and thermal characterizations of coordination polymers derived from divalent metal ions and hydroxyl terminated polyurethane as ligand

    Science.gov (United States)

    Laxmi; Khan, Shabnam; Kareem, Abdul; Zafar, Fahmina; Nishat, Nahid

    2018-01-01

    A series of novel coordination polyurethanes [HTPU-M, where M = Mn(II) 'd5', Ni(II) 'd8', and Zn(II) 'd10'] have been synthesized to investigate the effect of divalent metal ions coordination on structure, thermal and adsorption properties of low molecular weight hydroxyl terminated polyurethane (HTPU). HTPU-M have been synthesized in situ where, sbnd OH group of HTPU (synthesized by the condensation polymerization reaction of ethylene glycol (EG) and toluene diisocyanate (TDI) in presence of catalyst) on condensation polymerization with metal acetate in presence of acid catalyst synthesized HTPU-M followed by coordination of metal ions with hetero atoms. The structure, composition and geometry of HTPU-M have been confirmed by vibrational spectrometry (FTIR), 1H NMR, elemental analysis and UV-Visible spectroscopy. Morphological structures of HTPU-M were analyzed by X-Ray Diffraction analysis (XRD), Field Emission Scanning Electron Microscope (FE-SEM) with Energy Dispersive X-ray spectroscopy (EDX) and High Resolution Transmission Electron Microscope (HR-TEM) techniques. The thermal degradation pattern and thermal stability of HTPU-M in comparison to HTPU was investigated by thermal-gravimetric (TG)/differential thermal (DT), analyses along with Integral procedure decomposition temperature (IPDT) by Doyle method. The molecular weight of HTPU was determined by gel permeation chromatography (GPC). The preliminary adsorption/desorption studies of HTPU-M for Congo red (CR) was studied by batch adsorption techniques. The results indicated that HTPU-M have amorphous, layered morphology with higher number of nano-sized grooves in comparison to HTPU. Coordination of metal to HTPU plays a key role in enhancing the thermal stability [HTPU-Ni(II) > HTPU-Mn(II) > HTPU-Zn(II) > HTPU]. The HTPU-M can be utilized for industrial waste water treatment by removing environmental pollutants.

  12. Tipping Point

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    Full Text Available ... fall furniture head injury product safety television tipover tv Watch the video in Adobe Flash format. Almost ... accidents involving young children and furniture, appliance and tv tip-overs. The force of a large television ...

  13. Tipping Point

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    Full Text Available ... Point by CPSC Blogger September 22, 2009 appliance child Childproofing CPSC danger death electrical fall furniture head ... see news reports about horrible accidents involving young children and furniture, appliance and tv tip-overs. The ...

  14. Tipping Point

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    Full Text Available ... of a large television falling from tipping furniture can be staggering. A 50 lb. TV falls with ... story of a building. That kind of impact can kill a child or cause severe injuries. About ...

  15. Tipping Point

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    Full Text Available ... appliance child Childproofing CPSC danger death electrical fall furniture head injury product safety television tipover tv Watch ... reports about horrible accidents involving young children and furniture, appliance and tv tip-overs. The force of ...

  16. CPAP Tips

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    Full Text Available ... sleeping? Here are some tips from the U.S. Food and Drug Administration (FDA) on how to safely and effectively use your CPAP device. Category Education License Standard YouTube License Show more Show less ...

  17. Tipping Point

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    Full Text Available ... 16,000 (mostly young children) were treated in emergency rooms for tip-over related injuries in 2006, ... unaware of the deadly danger of this hidden hazard. Parents should include securing TVs, furniture, and appliances ...

  18. Tipping Point

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    Full Text Available ... CPSC danger death electrical fall furniture head injury product safety television tipover tv Watch the video in ... to prevent a tip-over tragedy. Share Post Facebook Twitter Google Plus Reddit Connect with Me:  Visit ...

  19. Characterizing Flow-Induced Vibrations of Fuel Assemblies for Future Liquid Metal Cooled Nuclear Reactors Using Quasi-Distributed Fibre-Optic Sensors

    Directory of Open Access Journals (Sweden)

    Ben De Pauw

    2017-08-01

    Full Text Available Excessive vibration of nuclear reactor components, such as the heat exchanger or the fuel assembly should be avoided as these can compromise the lifetime of these components and potentially lead to safety hazards. This issue is particularly relevant to new reactor designs that use liquid metal coolants. However, identifying adequate sensors or techniques that can be successfully applied to record the vibrations of the components in a flow of liquid metal at elevated temperatures is very challenging. In this paper, we demonstrate the precise measurements of the vibrations of a very representative mock-up of a fuel assembly in a lead-bismuth eutectic cooled installation using quasi-distributed fibre Bragg grating (FBG based sensors. The unique properties of these sensors, in combination with a dedicated integration and mounting approach, allows for accounting of the severe geometrical constraints and allows characterizing the vibration of the fuel assembly elements under nominal operation conditions. To that aim, we instrumented a single fuel pin within the fuel assembly with 84 FBGs, and conducted spectral measurements with an acquisition rate of up to 5000 measurements per second, enabling the monitoring of local strains of a few με. These measurements provide the information required to assess vibration-related safety hazards.

  20. Effective information campaign for management of exposure to hand-arm vibration in the metal and construction industries.

    Science.gov (United States)

    Sauni, Riitta; Toivio, Pauliina; Esko, Toppila; Pääkkönen, Rauno; Uitti, Jukka

    2015-01-01

    European Directive 2002/44/EC defines employers' responsibilities in the risk management of hand-arm vibration (HAV). However, the directive is still not completely implemented in all risk industries. The aim of our study was to determine whether it is possible to improve the recognition and management of the risks of HAV at workplaces with a one-year information campaign. A questionnaire on opinions and measures for controlling HAV exposure at workplaces was sent to all occupational safety representatives and occupational safety managers in the construction and metal industry in Finland (n=1887) and once again to those who responded to the first questionnaire (n=961) one year after the campaign. The campaign increased recognition of HAV in risk assessment from 57.0% to 68.3% (p=.001), increased measures to decrease exposure to HAV from 54.6% to 64.2% (p=.006) and increased the number of programmes to control the risks due to HAV (pconstruction and metal industries, proved to be effective in increasing the awareness of the risks of HAV and the measures needed to control exposure to HAV. A similar campaign can be recommended in the case of risks specific to certain occupations.

  1. Vibration Characteristics Determined for Stainless Steel Sandwich Panels With a Metal Foam Core for Lightweight Fan Blade Design

    Science.gov (United States)

    Ghosn, Louis J.; Min, James B.; Raj, Sai V.; Lerch, Bradley A.; Holland, Frederic A., Jr.

    2004-01-01

    The goal of this project at the NASA Glenn Research Center is to provide fan materials that are safer, weigh less, and cost less than the currently used titanium alloy or polymer matrix composite fans. The proposed material system is a sandwich fan construction made up of thin solid face sheets and a lightweight metal foam core. The stiffness of the sandwich structure is increased by separating the two face sheets by the foam layer. The resulting structure has a high stiffness and lighter weight in comparison to the solid facesheet material alone. The face sheets carry the applied in-plane and bending loads (ref. 1). The metal foam core must resist the transverse shear and transverse normal loads, as well as keep the facings supported and working as a single unit. Metal foams have ranges of mechanical properties, such as light weight, impact resistance, and vibration suppression (ref. 2), which makes them more suitable for use in lightweight fan structures. Metal foams have been available for decades (refs. 3 and 4), but the difficulties in the original processes and high costs have prevented their widespread use. However, advances in production techniques and cost reduction have created a new interest in this class of materials (ref. 5). The material chosen for the face sheet and the metal foam for this study was the aerospace-grade stainless steel 17-4PH. This steel was chosen because of its attractive mechanical properties and the ease with which it can be made through the powder metallurgy process (ref. 6). The advantages of a metal foam core, in comparison to a typical honeycomb core, are material isotropy and the ease of forming complex geometries, such as fan blades. A section of a 17-4PH sandwich structure is shown in the following photograph. Part of process of designing any blade is to determine the natural frequencies of the particular blade shape. A designer needs to predict the resonance frequencies of a new blade design to properly identify a useful

  2. Vibrational dynamics of fullerene molecules adsorbed on metal surfaces studied with synchrotron infrared radiation

    Energy Technology Data Exchange (ETDEWEB)

    P. Rudolf; R. Raval; P. Dumas; Gwyn P. Williams

    2002-04-01

    Infrared (IR) spectroscopy of chemisorbed C{sub 60} on Ag (111), Au (110) and Cu (100) reveals that a non-IR-active mode becomes active upon adsorption, and that its frequency shifts proportionally with the charge transferred from the metal to the molecule by about 5 cm{sup -1} per electron. The temperature dependence of the frequency and the width of this IR feature have also been followed for C{sub 60>}/Cu (100) and were found to agree well with a weak anharmonic coupling (dephasing) to a low-frequency mode, which we suggest to be the frustrated translational mode of the adsorbed molecules.

    Additionally, the adsorption is accompanied by a broadband reflectance change, which is interpreted as due to the scattering of conduction electrons of the metal surface by the adsorbate. The reflectance change allows determination of the friction coefficient of the C{sub 60} molecules, which results in rather small values ({approx}2 x 10{sup 9}s{sup -1} for Ag and Au, and {approx}1.6 x 10{sup 9}s{sup -1} for Cu), consistent with a marked metallic character of the adsorbed molecules.

    Pre-dosing of alkali atoms onto the metal substrates drastically changes the IR spectra recorded during subsequent C{sub 60} deposition: anti-absorption bands, as well as an increase of the broadband reflectance, occur and are interpreted as due to strong electron-phonon coupling with induced surface states.

  3. Vibration-Assisted Sputter Coating of Cenospheres: A New Approach for Realizing Cu-Based Metal Matrix Syntactic Foams

    Directory of Open Access Journals (Sweden)

    Andrei Shishkin

    2017-01-01

    Full Text Available The coating of hollow alumino-silicate microspheres or cenospheres with thin layers of Cu by means of vibration-assisted magnetron sputtering yields a starting material with considerable potential for the production of new types of metal matrix syntactic foams as well as optimized variants of conventional materials of this kind. This study introduces the coating process and the production of macroscopic samples from the coated spheres via spark plasma sintering (SPS. The influence of processing parameters on the coating itself, and the syntactic foams are discussed in terms of the obtained density levels as a function of sintering temperature (which was varied between 850 and 1080 °C, time (0.5 to 4 min, and surface appearance before and after SPS treatment. Sintering temperatures of 900 °C and above were found to cause breaking-up of the homogeneous sputter coating into a net-like structure. This effect is attributed to wetting behavior of Cu on the alumino-silicate cenosphere shells. Cylindrical samples were subjected to conductivity measurements and mechanical tests, and the first performance characteristics are reported here. Compressive strengths for Cu-based materials in the density range of 0.90–1.50 g/cm3 were found to lie between 8.6 and 61.9 MPa, depending on sintering conditions and density. An approximate relationship between strength and density is suggested based on the well-known Gibson–Ashby law. Density-related strength of the new material is contrasted to similar findings for several types of established metal foams gathered from the literature. Besides discussing these first experimental results, this paper outlines the potential of coated microspheres as optimized filler particles in metal matrix syntactic foams, and suggests associated directions of future research.

  4. Tipping Point

    Medline Plus

    Full Text Available ... 24 hours a day. For young children whose home is a playground, it’s the best way to prevent a tip-over tragedy. Share Post Facebook Twitter ... Security, and Legal Notice | Accessibility Policy | Open Government @ CPSC | ...

  5. CPAP Tips

    Medline Plus

    Full Text Available ... 3 Tips for Sleeping With a CPAP - Duration: 2:02. WebMD 42,375 views 2:02 About to spend my first night using ... 534 views 4:39 CPAP Mask Tutorial - Duration: 2:19. somnomedics 35,554 views 2:19 CPAP ...

  6. Tipping Point

    Medline Plus

    Full Text Available ... 24 hours a day. For young children whose home is a playground, it’s the best way to prevent a tip-over tragedy. Share Post Facebook Twitter Google Plus Reddit Connect with Me:  Visit other Web ...

  7. CPAP Tips

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    Full Text Available ... sleeping? Here are some tips from the U.S. Food and Drug Administration (FDA) on how to safely ... Copyright Creators Advertise Developers +YouTube Terms Privacy Policy & Safety Send feedback Test new features Loading... Working... Sign ...

  8. CPAP Tips

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    Full Text Available ... are some tips from the U.S. Food and Drug Administration (FDA) on how to safely and effectively ... views 3:03 FDA CDER Regulatory Science: Improving Drug Review with Data Standards - Duration: 3:01. USFoodandDrugAdmin ...

  9. CPAP Tips

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    Full Text Available ... are some tips from the U.S. Food and Drug Administration (FDA) on how to safely and effectively ... views 9:28 FDA CDER Regulatory Science: Improving Drug Review with Data Standards - Duration: 3:01. USFoodandDrugAdmin ...

  10. CPAP Tips

    Medline Plus

    Full Text Available ... in to report inappropriate content. Sign in Transcript Statistics Add translations 200,671 views Like this video? ... 3 Tips for Sleeping With a CPAP - Duration: 2:02. WebMD 57,416 views 2:02 How ...

  11. CPAP Tips

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    Full Text Available ... some tips from the U.S. Food and Drug Administration (FDA) on how to safely and effectively use ... WebMD 42,592 views 2:02 How CPAP works 5_23_11.wmv - Duration: 3:03. KenWarnerRemoteSleep ...

  12. CPAP Tips

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    Full Text Available ... 3 Tips for Sleeping With a CPAP - Duration: 2:02. WebMD 44,809 views 2:02 Airing: the first hoseless, maskless, micro-CPAP ... 569 views 6:50 CPAP Mask Tutorial - Duration: 2:19. somnomedics 36,067 views 2:19 How ...

  13. Metal sheet thickness profile measurement method based on two-side line triangulation and continuous vibration compensation

    Science.gov (United States)

    Lehtonen, Petri; Miettinen, Jari; Keränen, Heimo; Vaarala, Tapio

    2008-04-01

    Dimension measurements in metal production are getting increasingly important to improve quality and yield. One important measurement is thickness profile, in this case of copper strip. Knowing the strip profile in entrance and exit side of milling line helps optimizing the milling depth and give information about tool wearing. In this study a comparative measurement method was traversing point measurement system. It gives profile as a series of points which take a relatively long time to measure. Now presented method is based on two-side optical triangulation formed by line illuminators and CMOS-cameras and enables instantaneous thickness profile measurement. Results from both sides are fixed together using reference plates on both ends of the measurement area. From 1.3 m stand-off distance, 1.4 m wide measurement area is achieved. This paper presents the measurement method and results of laboratory and on-line tests. Using laser line illumination the accuracy of thickness was 150 μm when measuring 9 mm thick test plate. Accuracy was limited by laser speckle during static calibration. Other illumination method based on white light was therefore tested and the accuracy was 12 μm correspondingly. Measurement time for one profile was 1 second and resolution in cross machine direction 50 mm after averaging. Now presented method enables thickness profile measurement of copper and other metal sheets. Using white light the accuracy is at same level as the present traversing point measurement. Method has also continuous reference measurement to compensate errors caused by vibration; therefore the system can be realized at reasonable cost.

  14. Detecting Molecular Rotational Dynamics Complementing the Low-Frequency Terahertz Vibrations in a Zirconium-Based Metal-Organic Framework

    Science.gov (United States)

    Ryder, Matthew R.; Van de Voorde, Ben; Civalleri, Bartolomeo; Bennett, Thomas D.; Mukhopadhyay, Sanghamitra; Cinque, Gianfelice; Fernandez-Alonso, Felix; De Vos, Dirk; Rudić, Svemir; Tan, Jin-Chong

    2017-06-01

    We show clear experimental evidence of cooperative terahertz (THz) dynamics observed below 3 THz (˜100 cm-1 ), for a low-symmetry Zr-based metal-organic framework structure, termed MIL-140A [ZrO (O2C-C 6H4-CO2) ]. Utilizing a combination of high-resolution inelastic neutron scattering and synchrotron radiation far-infrared spectroscopy, we measured low-energy vibrations originating from the hindered rotations of organic linkers, whose energy barriers and detailed dynamics have been elucidated via ab initio density functional theory calculations. The complex pore architecture caused by the THz rotations has been characterized. We discovered an array of soft modes with trampolinelike motions, which could potentially be the source of anomalous mechanical phenomena such as negative thermal expansion. Our results demonstrate coordinated shear dynamics (2.47 THz), a mechanism which we have shown to destabilize the framework structure, in the exact crystallographic direction of the minimum shear modulus (Gmin ).

  15. Analysis of functional organic molecules at noble metal surfaces by means of vibrational spectroscopies

    Energy Technology Data Exchange (ETDEWEB)

    Leyssner, Felix

    2011-10-24

    The goal of this work is to optimize the efficiency of photoinduced molecular switching processes on surfaces via controlled variations of the adsorption and electronic properties of the switch. We investigated the influence of external stimuli, i.e. photons and thermal activation, on surface bound molecular switches undergoing trans/cis-isomerizations and ring-opening/closing-reactions, respectively. High resolution electron energy loss spectroscopy (HREELS) and sum-frequency generation (SFG) spectroscopy have been used as the main tools to investigate the adsorption behavior and the molecular switching properties. Two basic concepts of coupling the molecular switch to the surface have been studied: (i) physisorbed or weakly chemisorbed systems deposited on noble metal surfaces under UHV conditions and (ii) molecular switches bound covalently via anchor groups. In the HREELS study following concept (i), we investigated the adsorption geometry and isomerization behavior of various molecular switches on metal substrates which are able to undergo a photoinduced trans/cis-isomerization in solution. We investigated three isoelectronic molecules on Au where we systematically changed the photochemically active group from the diazo-group in an azobenzene-derivative (on Cu(111)) to the imine-group, and the vinylene-group, respectively. Finding the photoisomerization quenched for all systems we observed considerable differences in their thermal isomerization behavior. Comparable we find the photoinduced ring-opening/closing-reaction of spiropyran quenched on Au(111) but a thermally induced ring-opening reaction resulting in the open form being strongly stabilized by the metal. SFG spectroscopy is employed to investigate the reversible, photoinduced trans/cis-isomerization of an azobenzene-functionalized self-assembled monolayer (SAM) on gold using a tripodal linker system. In consequence of the decoupling provided by the tripodal linker, the switching behavior of the

  16. A structure-based analysis of the vibrational spectra of nitrosyl ligands in transition-metal coordination complexes and clusters

    Science.gov (United States)

    De La Cruz, Carlos; Sheppard, Norman

    2011-01-01

    The vibrational spectra of nitrogen monoxide or nitric oxide (NO) bonded to one or to several transition-metal (M) atom(s) in coordination and cluster compounds are analyzed in relation to the various types of such structures identified by diffraction methods. These structures are classified in: (a) terminal (linear and bent) nitrosyls, [M(σ-NO)] or [M(NO)]; (b) twofold nitrosyl bridges, [M 2(μ 2-NO)]; (c) threefold nitrosyl bridges, [M 3(μ 3-NO)]; (d) σ/π-dihaptonitrosyls or " side-on" nitrosyls; and (e) isonitrosyls (oxygen-bonded nitrosyls). Typical ranges for the values of internuclear N-O and M-N bond-distances and M-N-O bond-angles for linear nitrosyls are: 1.14-1.20 Å/1.60-1.90 Å/180-160° and for bent nitrosyls are 1.16-1.22 Å/1.80-2.00 Å/140-110°. The [M 2(μ 2-NO)] bridges have been divided into those that contain one or several metal-metal bonds and those without a formal metal/metal bond (M⋯M). Typical ranges for the M-M, N-O, M-N bond distances and M-N-M bond angles for the normal twofold NO bridges are: 2.30-3.00 Å/1.18-1.22 Å/1.80-2.00 Å/90-70°, whereas for the analogous ranges of the long twofold NO bridges these are 3.10-3.40 Å/1.20-1.24 Å/1.90-2.10 Å/130-110°. In both situations the N-O vector is approximately at right angle to the M-M (or M⋯M) vector within the experimental error; i.e. the NO group is symmetrical bonded to the two metal atoms. In contrast the threefold NO bridges can be symmetrically or unsymmetrically bonded to an M 3-plane of a cluster compound. Characteristic values for the N-O and M-N bond-distances of these NO bridges are: 1.24-1.28 Å/1.80-1.90 Å, respectively. As few dihaptonitrosyl and isonitrosyl complexes are known, the structural features of these are discussed on an individual basis. The very extensive vibrational spectroscopy literature considered gives emphasis to the data from linearly bonded NO ligands in stable closed-shell metal complexes; i.e. those which are consistent with the

  17. Tip enhancement

    CERN Document Server

    Kawata, Satoshi

    2007-01-01

    This book discusses the recent advances in the area of near-field Raman scattering, mainly focusing on tip-enhanced and surface-enhanced Raman scattering. Some of the key features covered here are the optical structuring and manipulations, single molecule sensitivity, analysis of single-walled carbon nanotubes, and analytic applications in chemistry, biology and material sciences. This book also discusses the plasmonic materials for better enhancement, and optical antennas. Further, near-field microscopy based on second harmonic generation is also discussed. Chapters have been written by some of the leading scientists in this field, who present some of their recent work in this field.·Near-field Raman scattering·Tip-enhanced Raman spectroscopy·Surface-enhanced Raman spectroscopy·Nano-photonics·Nanoanalysis of Physical, chemical and biological materials beyond the diffraction limits·Single molecule detection

  18. The metal-tool contact friction at the ultrasonic vibration drawing of ball-bearing steel wires

    Directory of Open Access Journals (Sweden)

    Susan, Mihai

    1999-12-01

    Full Text Available The friction reversion mechanism during the ultrasonic vibration drawing (UVD of wires has been detailed for the case when the die is located at the oscillation maxima of the waves and actuated parallel to the friction force direction. The decrease of the drawing force for the UVD technology as compared to classical drawing has been explained by means of the intermittent contact in the metal-die forming area. A relationship has been derived for the UVD friction coefficient, μUS that allowed the analytical determination of the drawing force. In the case of the Romanian RUL 1V (AISI 52100 ball bearing steel wires, a good agreement has been found between the analytical and the experimental values of the drawing forces that have decreased, as compared to classical drawing, by more than 5 % for drawing rates lower than 0.66m/s.

    Se hace un análisis pormenorizado del mecanismo de reversión de la fricción al estirado por vibraciones ultrasonoras (EVU de los alambres, para el caso en que la trefiladora está ubicada en los máximos de oscilación de las ondas y activada paralelamente a la dirección de estirado. La disminución de la fuerza de estirado para la tecnología EVU en comparación con el estirado clásico, se ha explicado a través del contacto intermitente en el área de deformación metal-herramienta. Se halló una relación para el coeficiente de fricción EVU, μUS que permitió la determinación analítica de la fuerza de estirado. En el caso de los alambres de acero rumano de rodamientos RUL 1V (AISI 52100 se encontró una justa concordancia entre los valores analítico y experimental de la fuerza de estirado que, en comparación con los de estirado clásico, se encontraron disminuidos en más de un 5 % para velocidades de estirado menores de 0,66m/s.

  19. Blade Vibration Measurement System

    Science.gov (United States)

    Platt, Michael J.

    2014-01-01

    The Phase I project successfully demonstrated that an advanced noncontacting stress measurement system (NSMS) could improve classification of blade vibration response in terms of mistuning and closely spaced modes. The Phase II work confirmed the microwave sensor design process, modified the sensor so it is compatible as an upgrade to existing NSMS, and improved and finalized the NSMS software. The result will be stand-alone radar/tip timing radar signal conditioning for current conventional NSMS users (as an upgrade) and new users. The hybrid system will use frequency data and relative mode vibration levels from the radar sensor to provide substantially superior capabilities over current blade-vibration measurement technology. This frequency data, coupled with a reduced number of tip timing probes, will result in a system capable of detecting complex blade vibrations that would confound traditional NSMS systems. The hardware and software package was validated on a compressor rig at Mechanical Solutions, Inc. (MSI). Finally, the hybrid radar/tip timing NSMS software package and associated sensor hardware will be installed for use in the NASA Glenn spin pit test facility.

  20. Development of apertureless near-field scanning optical microscope tips for tip-enhanced Raman spectroscopy.

    Science.gov (United States)

    Kodama, T; Umezawa, T; Watanabe, S; Ohtani, H

    2008-02-01

    In this study, we suggested two types of novel metallized tip for the apertureless near-field scanning optical microscope probe. The first is a silver nanorod immobilized tip and the other is a double metallized probe. We calculated the electric field enhancement factor and the electric field distribution of a single sphere, aggregated spheres, an ellipse and a nanorod by the finite-differential time-domain method to improve the silver nanosphere immobilized tip developed in our previous studies. The enhanced field of the nanorod is localized at the external surfaces. The simulation results of the nanorod revealed that the position of the maximum peak is shifted to a longer wavelength and that its electric field enhancement factor increases as the aspect ratio increases. Thus, we developed the silver nanorod immobilized tip, and the tip-enhanced Raman spectrum of rhodamine 6G molecule on the substrate could be measured by the tip though it could not be detected by the previous nanosphere immobilized tip. Further, the finite-differential time-domain calculation predicted that the double metallized tips considerably enhance the electric field and that its enhancement factor in the longer wavelength region (500-600 nm) does not decrease when the tip is rounded. The results show that the proposed metallized tips were useful for the apertureless near-field scanning optical microscope system.

  1. Understanding the Plasmonics of Nanostructured Atomic Force Microscopy Tips

    CERN Document Server

    Sanders, Alan; Zhang, Liwu; Turek, Vladimir; Sigle, Daniel O; Lombardi, Anna; Weller, Lee; Baumberg, Jeremy J

    2016-01-01

    Structured metallic tips are increasingly important for optical spectroscopies such as tip-enhanced Raman spectroscopy (TERS), with plasmonic resonances frequently cited as a mechanism for electric field enhancement. We probe the local optical response of sharp and spherical-tipped atomic force microscopy (AFM) tips using a scanning hyperspectral imaging technique to identify plasmonic behaviour. Localised surface plasmon resonances which radiatively couple with far-field light are found only for spherical AFM tips, with little response for sharp AFM tips, in agreement with numerical simulations of the near-field response. The precise tip geometry is thus crucial for plasmon-enhanced spectroscopies, and the typical sharp cones are not preferred.

  2. Vibration-Assisted Sputter Coating of Cenospheres: A New Approach for Realizing Cu-Based Metal Matrix Syntactic Foams

    National Research Council Canada - National Science Library

    Shishkin, Andrei; Drozdova, Maria; Kozlov, Viktor; Hussainova, Irina; Lehmhus, Dirk

    2017-01-01

      The coating of hollow alumino-silicate microspheres or cenospheres with thin layers of Cu by means of vibration-assisted magnetron sputtering yields a starting material with considerable potential...

  3. Tip Refinement Grafts: The Designer Tip.

    Science.gov (United States)

    Daniel, Rollin K

    2009-01-01

    In cosmetic rhinoplasty, the patient's satisfaction is most often determined by the quality of the tip surgery, but perfecting a technique for consistently attractive tips can be challenging. As a result, rhinoplasty surgery is now entering a new era of "designer tip" operations, wherein surgeons can employ a combination of open suture tip techniques and tip refinement grafts to achieve consistent results. The grafts are made from excised lateral crural cartilage and, depending upon the specific aesthetic goals, the shape can include the following:domal, shield, diamond, folded, or combination. It is possible to alter dome-defining points, tip point, projection,definition, volume, and size and shape. A study of 100 consecutive female rhinoplasties indicated that tip sutures alone were used in 36% of cases, while a tip refinement graft was added to a sutured tip in 59% of cases.

  4. To tip or not to tip?

    OpenAIRE

    Saayman, Melville

    2014-01-01

    Tipping is an important source of income for a variety of occupations in the hospitality and tourism industry. One such occupation is waitressing and although much research has been done, especially in America, very little has been done in African countries. The purpose of this paper is therefore to determine the reasons why people tip or do not tip, as well as which socio-demographic and behavioural variables have the greatest influence on tipping. A survey was conducted at restaurants durin...

  5. Effect of vibrating electrode on temperature profiles, fluid flow, and pool shape in ESR system based on a comprehensive coupled model

    Directory of Open Access Journals (Sweden)

    Fang Wang

    2015-07-01

    Full Text Available The vibrating electrode method was proposed in the electro-slag remelting (ESR process in this paper, and the effect of vibrating electrode on the solidification structure of ingot was studied. A transient three-dimensional (3D coupled mathematical model was established to simulate the electromagnetic phenomenon, fluid flow as well as pool shape in the ESR process with the vibrating electrode. The finite element volume method is developed to solve the electromagnetic field using ANSYS mechanical APDL software. Moreover, the electromagnetic force and Joule heating are interpolated as the source term of the momentum and energy equations. The multi-physical fields have been investigated and compared between the traditional electrode and the vibrating electrode in the ESR process. The results show that the drop process of metal droplets with the traditional electrode is scattered randomly. However, the drop process of metal droplets with the vibrating electrode is periodic. The highest temperature of slag layer with the vibrating electrode is higher than that with the traditional electrode, which can increase the melting rate due to the enhanced heat transfer in the vicinity of the electrode tip. The results also show that when the amplitude and frequency of the vibrating electrode increase, the cycle of drop process of metal droplets decreases significantly.

  6. Tips for Daily Living

    Science.gov (United States)

    ... over the country who’ve created or discovered adaptive and often innovative ways to get things done! Submit your tips today! Check out our Tips for Submitting Tips ! Take a video (it can even be on a smartphone!) or write down your tips. Complete the submission ...

  7. Wideband Piezomagnetoelastic Vibration Energy Harvesting

    DEFF Research Database (Denmark)

    Lei, Anders; Thomsen, Erik Vilain

    2014-01-01

    This work presents a small-scale wideband piezomagnetoelastic vibration energy harvester (VEH) aimed for operation at frequencies of a few hundred Hz. The VEH consists of a tape-casted PZT cantilever with thin sheets of iron foil attached on each side of the free tip. The wideband operation...

  8. Supermodularity and Tipping

    OpenAIRE

    Geoffrey Heal; Howard Kunreuther

    2006-01-01

    We model tipping as a game-theoretic phenomenon and investigate the connection between supermodular games, tipping of equilibria and cascading, and apply the results to issues that arise in the context of homeland security and computer security. We show that tipping and cascading can occur in supermodular games and that "increasing differences"is a sufficient condition for tipping. Supermodularity and tipping of equilibria are closely related. We relate our results to Schelling%u2019s early w...

  9. Mapping cavitation activity around dental ultrasonic tips.

    Science.gov (United States)

    Walmsley, A Damien; Lea, Simon C; Felver, Bernhard; King, David C; Price, Gareth J

    2013-05-01

    Cavitation arising within the water around the oscillating ultrasonic scaler tip is an area that may lead to advances in enhancing biofilm removal. The aim of this study is to map the occurrence of cavitation around scaler tips under loaded conditions. Two designs of piezoelectric ultrasonic scaling probes were evaluated with a scanning laser vibrometer and luminol dosimetric system under loaded (100 g/200 g) and unloaded conditions. Loads were applied to the probe tips via teeth mounted in a load-measuring apparatus. There was a positive correlation between probe displacement amplitude and cavitation production for ultrasonic probes. The position of cavitation at the tip of each probe was greater under loaded conditions than unloaded and for the longer P probe towards the tip. Whilst increasing vibration displacement amplitude of ultrasonic scalers increases the occurrence of cavitation, factors such as the length of the probe influence the amount of cavitation activity generated. The application of load affects the production of cavitation at the most clinically relevant area-the tip. Loading and the design of ultrasonic scalers lead to maximising the occurrence of the cavitation at the tip and enhance the cleaning efficiency of the scaler.

  10. Healthy Vision Tips

    Science.gov (United States)

    ... NEI for Kids > Healthy Vision Tips All About Vision About the Eye Ask a Scientist Video Series ... Links to More Information Optical Illusions Printables Healthy Vision Tips Healthy vision starts with you! Use these ...

  11. The TIPS Liquidity Premium

    DEFF Research Database (Denmark)

    Andreasen, Martin Møller; Christensen, Jens H.E.; Simon Riddell, Simon

    We introduce an arbitrage-free term structure model of nominal and real yields that accounts for liquidity risk in Treasury inflation-protected securities (TIPS). The novel feature of our model is to identify liquidity risk from individual TIPS prices by accounting for the tendency that TIPS, lik...

  12. Tip studies using CFD and comparison with tip loss models

    DEFF Research Database (Denmark)

    Hansen, Martin Otto Laver; Johansen, J.

    2004-01-01

    The flow past a rotating LM8.2 blade equipped with two different tips are computed using CFD. The different tip flows are analysed and a comparison with two different tip loss models is made. Keywords: tip flow, aerodynamics, CFD......The flow past a rotating LM8.2 blade equipped with two different tips are computed using CFD. The different tip flows are analysed and a comparison with two different tip loss models is made. Keywords: tip flow, aerodynamics, CFD...

  13. Arctic climate tipping points.

    Science.gov (United States)

    Lenton, Timothy M

    2012-02-01

    There is widespread concern that anthropogenic global warming will trigger Arctic climate tipping points. The Arctic has a long history of natural, abrupt climate changes, which together with current observations and model projections, can help us to identify which parts of the Arctic climate system might pass future tipping points. Here the climate tipping points are defined, noting that not all of them involve bifurcations leading to irreversible change. Past abrupt climate changes in the Arctic are briefly reviewed. Then, the current behaviour of a range of Arctic systems is summarised. Looking ahead, a range of potential tipping phenomena are described. This leads to a revised and expanded list of potential Arctic climate tipping elements, whose likelihood is assessed, in terms of how much warming will be required to tip them. Finally, the available responses are considered, especially the prospects for avoiding Arctic climate tipping points.

  14. Effects of Cutting Tool Parameters on Vibration

    Directory of Open Access Journals (Sweden)

    Ince Mehmet Alper

    2016-01-01

    Full Text Available This paper presents of the influence on vibration of Co28Cr6Mo medical alloy machined on a CNC lathe based on cutting parameters (rotational speed, feed rate, depth of cut and tool tip radius. The influences of cutting parameters have been presented in graphical form for understanding. To achieve the minimum vibration, the optimum values obtained for rpm, feed rate, depth of cut and tool tip radius were respectively, 318 rpm, 0.25 mm/rev, 0.9 mm and 0.8 mm. Maximum vibration has been revealed the values obtained for rpm, feed rate, depth of cut and tool tip radius were respectively, 636 rpm, 0.1 mm/rev, 0,5 mm and 0.8 mm.

  15. Investigation of Heat Transfer and Magnetohydrodynamic Flow in Electroslag Remelting Furnace Using Vibrating Electrode

    Science.gov (United States)

    Wang, Fang; Wang, Qiang; Lou, Yanchun; Chen, Rui; Song, Zhaowei; Li, Baokuan

    2016-01-01

    A transient three-dimensional (3D) coupled mathematical model has been developed to understand the effect of a vibrating electrode on the electromagnetic, two-phase flow and temperature fields as well as the solidification in the electroslag remelting (ESR) process. With the magnetohydrodynamic model, the Joule heating and Lorentz force, which are the source terms in the energy and momentum equations, are recalculated at each iteration as a function of the phase distribution. The influence of the vibrating electrode on the formation of the metal droplet is demonstrated by the volume of fluid approach. Additionally, the solidification of the metal is modeled by an enthalpy-based technique, in which the mushy zone is treated as a porous medium with porosity equal to the liquid fraction. The present work is the first attempt to investigate the innovative technology of the ESR process with a vibrating electrode by a transient 3D comprehensive model. A reasonable agreement between the experiment and simulation is obtained. The results indicate that the whole process is presented as a periodic activity. When the metal droplets fall from the tip of the electrode, the horizontal component of velocity will generate electrode vibration. This will lead to the distribution variation of the flow field in the slag layer. The variation of temperature distribution occurs regularly and is periodically accompanied by the behavior of the falling metal droplets. With the decreasing vibrating frequency and amplitude, the relative velocity of the electrode and molten slag increase accordingly. The diameter of the molten droplets, the maximum temperature and the depth of the molten pool gradually become smaller, lower and shallower.

  16. Combined effects of ultrasonic vibration and manganese on Fe-containing inter-metallic compounds and mechanical properties of Al-17Si alloy with 3wt.%Fe

    Directory of Open Access Journals (Sweden)

    Lin Chong

    2013-05-01

    Full Text Available The research studied the combined effects of ultrasonic vibration (USV and manganese on the Fe-containing inter-metallic compounds and mechanical properties of Al-17Si-3Fe-2Cu-1Ni (wt.% alloys. The results showed that, without USV, the alloys with 0.4wt.% Mn or 0.8wt.% Mn both contain a large amount of coarse plate-like δ-Al4(Fe,MnSi2 phase and long needle-like β-Al5(Fe,MnSi phase. When the Mn content changes from 0.4wt.% to 0.8wt.% in the alloys, the amount and the length of needle-like β-Al5(Fe,MnSi phase decrease and the plate-like δ-Al4(Fe,MnSi2 phase becomes much coarser. After USV treatment, the Fe-containing compounds in the alloys are refined and exist mainly as δ-Al4(Fe,MnSi2 particles with an average grain size of about 20 μm, and only a small amount of β-Al5(Fe,MnSi phase remains. With USV treatment, the ultimate tensile strengths (UTS of the alloys containing 0.4wt.%Mn and 0.8wt.%Mn at room temperature are 253 MPa and 262 MPa, respectively, and the ultimate tensile strengths at 350 °C are 129 MPa and 135 MPa, respectively. It is considered that the modified morphology and uniform distribution of the Fe-containing inter-metallic compounds, which are caused by the USV process, are the main reasons for the increase in the tensile strength of these two alloys.

  17. Data Management Techniques for Blade Vibration Analysis

    Directory of Open Access Journals (Sweden)

    Przysowa Radosław

    2016-07-01

    Full Text Available Well-designed procedures are required to handle large amounts of data, generated by complex measurement systems used in engine tests. The paper presents selected methodologies and software tools for characterisation and monitoring of blade vibration. Common file formats and data structures as well as methods to process and visualise tip-timing data are discussed. Report Generation Framework (RGF developed in Python is demonstrated as a flexible tool for processing and publishing blade vibration results.

  18. Vibration Damping Circuit Card Assembly

    Science.gov (United States)

    Hunt, Ronald Allen (Inventor)

    2016-01-01

    A vibration damping circuit card assembly includes a populated circuit card having a mass M. A closed metal container is coupled to a surface of the populated circuit card at approximately a geometric center of the populated circuit card. Tungsten balls fill approximately 90% of the metal container with a collective mass of the tungsten balls being approximately (0.07) M.

  19. Tip Studies using CFD and Comparison with Tip Loss Models

    DEFF Research Database (Denmark)

    Hansen, Martin Otto Laver

    2004-01-01

    The flow past a 95 kW Tellus rotor equipped with LM8.2 blades is computed using computational fluid dynamics for a standard tip and a swept tip. The difference in the near-tip flow for the two tips for various tip speed ratios is examined and 3D airfoil data are extracted. The radial distribution...

  20. Tip-modified Propellers

    DEFF Research Database (Denmark)

    Andersen, Poul

    1999-01-01

    wings. The literature on four different designs is reviewed: the end-plate propeller; the two-sided, shifted end-plate propeller; the tip-fin propeller; and the bladelet propeller. The conclusion is that it is indeed possible to design tip-modified propellers that, relative to an optimum conventional...

  1. 10 Data Visualization Tips

    International Development Research Centre (IDRC) Digital Library (Canada)

    Office 2004 Test Drive User

    1. 10 Data Visualization Tips. Data visualizations are an effective tool to communicate research. But to realize their potential, designers should follow these tips to help readers decode their visualizations. 1. Keep it simple! This is the golden rule. Always choose the simplest way to convey your information. 2. Have a specific ...

  2. Southwestern Pine Tip Moth

    Science.gov (United States)

    Daniel T. Jennings; Robert E. Stevens

    1982-01-01

    The southwestern pine tip moth, Rhyacionia neomexicana (Dyar), injures young ponderosa pines (Pinus ponderosa Dougl. ex Laws) in the Southwest, central Rockies, and midwestern plains. Larvae feed on and destroy new, expanding shoots, often seriously reducing terminal growth of both naturally regenerated and planted pines. The tip moth is especially damaging to trees on...

  3. ADHD: Tips to Try

    Science.gov (United States)

    ... Situations Talking to Your Parents - or Other Adults ADHD: Tips to Try KidsHealth > For Teens > ADHD: Tips to Try Print A A A en español TDAH: Consejos que puedes probar ADHD , short for attention deficit hyperactivity disorder , is a ...

  4. Monitoring vibrations

    Energy Technology Data Exchange (ETDEWEB)

    Tiryaki, B. [Hacettepe University (Turkey). Dept. of Mining Engineering

    2003-12-01

    The paper examines the prediction and optimisation of machine vibrations in longwall shearers. Underground studies were carried out at the Middle Anatolian Lignite Mine, between 1993 and 1997. Several shearer drums with different pick lacing arrangements were designed and tested on double-ended ranging longwall shearers employed at the mine. A computer program called the Vibration Analysis Program (VAP) was developed for analysing machine vibrations in longwall shearers. Shearer drums that were tested underground, as well as some provided by leading manufacturers, were analyzed using these programs. The results of the experiments and computer analyses are given in the article. 4 refs., 9 figs.

  5. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

    Medline Plus

    Full Text Available ... the liver). Portal hypertension can also occur in children, although children are much less likely to require a TIPS. ... intentionally to solve the problem. Although extremely rare, children may also require a TIPS procedure. TIPS in ...

  6. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

    Medline Plus

    Full Text Available ... pressure. top of page How does the procedure work? A TIPS reroutes blood flow in the liver ... intentionally to solve the problem. Although extremely rare, children may also require a TIPS procedure. TIPS in ...

  7. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

    Medline Plus

    Full Text Available ... risks? What are the limitations of TIPS? What is a Transjugular Intrahepatic Portosystemic Shunt (TIPS)? A transjugular intrahepatic ... top of page What are some common uses of the procedure? A TIPS is used to treat ...

  8. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

    Medline Plus

    Full Text Available ... What are the limitations of TIPS? What is a Transjugular Intrahepatic Portosystemic Shunt (TIPS)? A transjugular intrahepatic ... of page What are some common uses of the procedure? A TIPS is used to treat the ...

  9. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

    Medline Plus

    Full Text Available ... vs. risks? What are the limitations of TIPS? What is a Transjugular Intrahepatic Portosystemic Shunt (TIPS)? A ... likely to require a TIPS. top of page What are some common uses of the procedure? A ...

  10. Vibrational Diver

    Science.gov (United States)

    Kozlov, Victor; Ivanova, Alevtina; Schipitsyn, Vitalii; Stambouli, Moncef

    2014-10-01

    The paper is concerned with dynamics of light solid in cavity with liquid subjected to rotational vibration in the external force field. New vibrational phenomenon - diving of a light cylinder to the cavity bottom is found. The experimental investigation of a horizontal annulus with a partition has shown that under vibration a light body situated in the upper part of the layer is displaced in a threshold manner some distance away from the boundary. In this case the body executes symmetric tangential oscillations. An increase of the vibration intensity leads to a tangential displacement of the body near the external boundary. This displacement is caused by the tangential component of the vibrational lift force, which appears as soon as the oscillations lose symmetry. In this case the trajectory of the body oscillatory motion has the form of a loop. The tangential lift force makes stable the position of the body on the inclined section of the layer and even in its lower part. A theoretical interpretation has been proposed, which explains stabilization of a quasi-equilibrium state of a light body near the cavity bottom in the framework of vibrational hydromechanics.

  11. Thermoelectric measurements using different tips in atomic force microscopy

    Science.gov (United States)

    Kushvaha, S. S.; Hofbauer, W.; Loke, Y. C.; Singh, Samarendra P.; O'Shea, S. J.

    2011-04-01

    We use conducting atomic force microscopy (AFM) in ultra high vacuum to measure the thermoelectric power of Au, Pt, and 3,4,9,10-perylene tetracarboxylic dianhydride (PTCDA) films. Tips coated with thick (1200 nm) Pt films or highly doped diamond film give reproducible data. The thermoelectric power of metal junctions formed with diamond tips is high but dominated by the diamond material thus making diamond tips of limited applicability in thermovoltage AFM. Pt coated tips on Au or Pt films gives small thermovoltage signal, making quantitative analysis of the thermopower on metal sample problematic. The thermovoltage AFM technique appears best suited to study organic thin films and the thermoelectric power of 1.5 nm and 2 nm thick PTCDA deposited on Au measured with Pt tips is -342 and -372 μV/K, respectively. The negative sign indicates that the lowest unoccupied molecular orbital level dominates electrical transport.

  12. Eye Drop Tips

    Science.gov (United States)

    ... Involved News About Us Donate In This Section Eye Drop Tips en Español email Send this article ... the reach of children. Steps For Putting In Eye Drops: Start by tilting your head backward while ...

  13. Incontinence Treatment: Dietary Tips

    Science.gov (United States)

    ... well as some fruits). Some foods are gas producing (e.g., beans, cabbage, legumes, cauliflower, broccoli, lentils, ... supporting IFFGD with a small tax-deductible donation. Lifestyle Changes Dietary Tips Medication Bowel Management Biofeedback Surgical ...

  14. Tips from the Classroom.

    Science.gov (United States)

    Hess, Natalie; And Others

    1995-01-01

    Six classroom tips for language teachers focus on creating a congenial classroom environment, integrating listening and reading skills, teaching idioms from tabloid newspapers, cooperative learning in honors courses, grammar games, and teaching culture through personalized automobile license plate messages. (MDM)

  15. Tips for Chronic Pain

    Science.gov (United States)

    Patient Education Sheet Tips for Chronic Pain The SSF thanks Stuart S. Kassan, MD, FACP, Clinical Professor of Medicine, University of Colorado Health Sciences Center, Denver, Colorado, for authoring ...

  16. A Blade Tip Timing Method Based on a Microwave Sensor

    Directory of Open Access Journals (Sweden)

    Jilong Zhang

    2017-05-01

    Full Text Available Blade tip timing is an effective method for blade vibration measurements in turbomachinery. This method is increasing in popularity because it is non-intrusive and has several advantages over the conventional strain gauge method. Different kinds of sensors have been developed for blade tip timing, including optical, eddy current and capacitance sensors. However, these sensors are unsuitable in environments with contaminants or high temperatures. Microwave sensors offer a promising potential solution to overcome these limitations. In this article, a microwave sensor-based blade tip timing measurement system is proposed. A patch antenna probe is used to transmit and receive the microwave signals. The signal model and process method is analyzed. Zero intermediate frequency structure is employed to maintain timing accuracy and dynamic performance, and the received signal can also be used to measure tip clearance. The timing method uses the rising and falling edges of the signal and an auto-gain control circuit to reduce the effect of tip clearance change. To validate the accuracy of the system, it is compared experimentally with a fiber optic tip timing system. The results show that the microwave tip timing system achieves good accuracy.

  17. Vibrating minds

    CERN Document Server

    2009-01-01

    Ed Witten is one of the leading scientists in the field of string theory, the theory that describes elementary particles as vibrating strings. This week he leaves CERN after having spent a few months here on sabbatical. His wish is that the LHC will unveil supersymmetry.

  18. Modelling of micro vibration energy harvester considering size effect

    Science.gov (United States)

    Li, Chuangye; Huo, Rui; Wang, Weike

    2017-09-01

    Considering increase of stiffness caused by size effect, equivalent Young's modulus was introduced for futher analysis. Experimental platform was established to test vibration characteristics. Dynamic equation for micro piezoelectric cantilever beam considering size effect was studied with finite element analysis and experiment. Results shows it is accurate. Based on that, dynamic model for micro vibration energy harvester was improved, a T-type micro vibration energy harvester was designed and fabricated. Resonant frequency, tip displacement and output voltage of the harvester were obtained. Comparing with macroscopic model for vibration harvester, improved one reduces errors by 13%, 35% and 22%.

  19. On the development of a magnetoresistive sensor for blade tip timing and blade tip clearance measurement systems

    Science.gov (United States)

    Tomassini, R.; Rossi, G.; Brouckaert, J.-F.

    2016-10-01

    A simultaneous blade tip timing (BTT) and blade tip clearance (BTC) measurement system enables the determination of turbomachinery blade vibrations and ensures the monitoring of the existing running gaps between the blade tip and the casing. This contactless instrumentation presents several advantages compared to the well-known telemetry system with strain gauges, at the cost of a more complex data processing procedure. The probes used can be optical, capacitive, eddy current as well as microwaves, everyone with its dedicated electronics and many existing different signal processing algorithms. Every company working in this field has developed its own processing method and sensor technology. Hence, repeating the same test with different instrumentations, the answer is often different. Moreover, rarely it is possible to achieve reliability for in-service measurements. Developments are focused on innovative instrumentations and a common standard. This paper focuses on the results achieved using a novel magnetoresistive sensor for simultaneous tip timing and tip clearance measurements. The sensor measurement principle is described. The sensitivity to gap variation is investigated. In terms of measurement of vibrations, experimental investigations were performed at the Air Force Institute of Technology (ITWL, Warsaw, Poland) in a real aeroengine and in the von Karman Institute (VKI) R2 compressor rig. The advantages and limitations of the magnetoresistive probe for turbomachinery testing are highlighted.

  20. Phase influence of combined rotational and transverse vibrations on the structural response

    Science.gov (United States)

    Habtour, Ed; Sridharan, Raman; Dasgupta, Abhijit; Robeson, Mark; Vantadori, Sabrina

    2018-02-01

    The planar dynamic response of a cantilever metallic beam structure under combined harmonic base excitations (consisting of in-plane transverse and rotation about the out-of-plane transverse axis) was investigated experimentally. The important effect of the phase angle between the two simultaneous biaxial excitations on the beam tip displacement was demonstrated. The experiments were performed using a unique six degree-of-freedom (6-DoF) electrodynamic shaker with high control accuracy. The results showed that the beam tip displacement at the first flexural mode was amplified when the phase angle between the rotational and translational base excitations was increased. The beam nonlinear stiffness, on the other hand, simultaneously: (i) decreased due to fatigue damage accumulation, and (ii) increased due to an increase in the phase angle. The results were compared to the uniaxial excitation technique, where the principle of superposition was applied (mathematical addition of the structural response for each uniaxial excitation). The principle of superposition was shown to overestimate the structural response for low phase angles. Thus, the application of the superposition vibration testing as a substitute for multiaxial vibration testing may lead to over-conservatism and erroneous dynamic and reliability predictions.

  1. Gyroscopic Stability of Open Tipped Match Style Rifle Bullets

    CERN Document Server

    Courtney, Elya R

    2014-01-01

    Earlier work has produced formulas for predicting stability of rifle bullets of near uniform density and also for plastic-tipped rifle bullets. These formulas have been shown to be accurate to within 5%. However, the original Miller twist formula for metal bullets of near uniform density underestimates the stability of match style open tipped rifle bullets having a significant empty volume in the tip. This paper presents a new formula for accurately estimating the stability of these open tipped match style rifle bullets from parameters easily obtained such as the bullet mass, length, and depth of the empty space in the tip. The formula is tested by measuring the aerodynamic drag vs. predicted stability of several bullets over a range of stabilities.

  2. Taxicab tipping and sunlight.

    Science.gov (United States)

    Devaraj, Srikant; Patel, Pankaj C

    2017-01-01

    Does the level of sunlight affect the tipping percentage in taxicab rides in New York City? We examined this question using data on 13.82 million cab rides from January to October in 2009 in New York City combined with data on hourly levels of solar radiation. We found a small but statistically significant positive relationship between sunlight and tipping, with an estimated tipping increase of 0.5 to 0.7 percentage points when transitioning from a dark sky to full sunshine. The findings are robust to two-way clustering of standard errors based on hour-of-the-day and day-of-the-year and controlling for day-of-the-year, month-of-the-year, cab driver fixed effects, weather conditions, and ride characteristics. The NYC cab ride context is suitable for testing the association between sunlight and tipping due to the largely random assignment of riders to drivers, direct exposure to sunlight, and low confounding from variation in service experiences.

  3. Tips for Energy Savers.

    Science.gov (United States)

    Department of Energy, Washington, DC.

    According to 1986 U.S. Department of Energy data, 48% of our residential energy is used to heat and cool our homes, 16% goes for heating water, 12% is used to refrigerators and freezers, and the remaining 24% goes into lighting, cooking, and running appliances. This booklet contains tips for saving energy, including sections on: (1) draft-proof…

  4. Turbine-blade tip clearance and tip timing measurements using an optical fiber bundle sensor

    Science.gov (United States)

    Garcia, Iker; Beloki, Josu; Zubia, Joseba; Durana, Gaizka; Aldabaldetreku, Gotzon

    2013-04-01

    Traditional limitations of capacitive, inductive or discharging probe sensor for tip timing and tip clearance measurements are overcome by reflective intensity modulated optical fiber sensors. This paper presents the signals and results corresponding to a one stage turbine rig which rotor has 146 blades, obtained from a transonic wind-tunnel test. The probe is based on a trifurcated bundle of optical fibers that is mounted on turbine casing. It is composed of a central illuminating fiber that guides the light from a laser to the turbine blade, and two concentric rings of receiving fibers that collect the reflected light. Two photodetectors turn this reflected light signal from the receiving rings into voltage. The electrical signals are acquired and saved by a high-sample-rate oscilloscope. In tip clearance calculations the ratio of the signals provided by each ring of receiving fibers is evaluated and translated into distance. In the case of tip timing measurements, only one of the signals is considered to get the arrival time of the blade. The differences between the real and theoretical arrival times of the blades are used to obtain the deflections amplitude. The system provides the travelling wave spectrum, which presents the average vibration amplitude of the blades at a certain nodal diameter. The reliability of the results in the turbine rig testing facilities suggests the possibility of performing these measurements in real turbines under real working conditions.

  5. Tipping: Is it ever OK to skip the tip?

    National Research Council Canada - National Science Library

    N'dea Yancey-Bragg

    2017-01-01

    ..., the minimum wage for tipped workers can be also low as $2. 13. Delivery Apps like UberEats and Postmates don't require tips, although some offer suggested gratuities on their checkout page. (Uber on Tuesday just added the option to tip. ) Grubhub founder and CEO Matt Maloney strongly encourages a 10-15% tip. After all, delivery drivers aren't salaried work...

  6. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

    Medline Plus

    Full Text Available ... What are the limitations of TIPS? What is a Transjugular Intrahepatic Portosystemic Shunt (TIPS)? A transjugular intrahepatic ... code: Phone no: Thank you! Do you have a personal story about radiology? Share your patient story ...

  7. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

    Medline Plus

    Full Text Available ... TIPS. top of page What are some common uses of the procedure? A TIPS is used to ... the scanner by a cord. Some exams may use different transducers (with different capabilities) during a single ...

  8. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

    Medline Plus

    Full Text Available ... or bypass, without the risks that accompany open surgery. TIPS is a minimally invasive procedure that typically has a shorter recovery time than surgery. Your TIPS should have less of an effect ...

  9. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

    Medline Plus

    Full Text Available ... What are the limitations of TIPS? What is a Transjugular Intrahepatic Portosystemic Shunt (TIPS)? A transjugular intrahepatic ... taking our brief survey: Survey Do you have a personal story about radiology? Share your patient story ...

  10. Economic Behavior of Restaurant Tipping

    OpenAIRE

    Tin-Chun Lin

    2007-01-01

    This paper offers a thoughtful discussion of social norms and alternative economic viewpoints and analysis of restaurant tipping behavior. A survey of Louisiana residents was conducted to collect public opinions about tipping. The analysis suggests that social norms are indeed the primary reason for diner tipping. As long as consumer behavior is guided by social norms, social norms will costs for diners. The conclusion suggests that if customer's tipping behavior were completely guided by soc...

  11. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

    Medline Plus

    Full Text Available ... liver disease are at greater risk for worsening liver failure after TIPS. If your liver failure is severe, a TIPS may not be the best use and a different procedure may be needed to control your symptoms. ... ordinarily filtered out by the liver. The TIPS may cause too much of these ...

  12. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

    Medline Plus

    Full Text Available ... of page What are the limitations of TIPS? Patients with more advanced liver disease are at greater risk for worsening liver failure after TIPS. If your liver failure is severe, a TIPS may not be the best use and a different procedure may be needed ...

  13. Stability of magnetic tip/superconductor levitation systems

    Science.gov (United States)

    K. Alqadi, M.

    2015-11-01

    The vertical stability of a magnetic tip over a superconducting material is investigated by using the critical state and the frozen image models. The analytical expressions of the stiffness and the vibration frequency about the equilibrium position are derived in term of the geometrical parameters of the magnet/superconductor system. It is found that the stability of the system depends on the shape of the superconductor as well as its thickness.

  14. Phase transformation in AFM silicon tips

    Science.gov (United States)

    Kopycinska-Müller, M.; Barth, M.; Küttner, M.; Köhler, B.

    2017-09-01

    We confirmed the occurrence of phase transformations in an atomic force microscopy silicon tip during loading and unloading experiments performed on a polycrystalline Ti sample. The influence of the phase transformations on the effective mechanical and electrical properties of the tip was observed with the help of load-unload curves measured simultaneously for the tip-sample contact stiffness k * and the effective electrical resistance of the system R eff. We used the atomic force acoustic microscopy (AFAM) method to determine the values of k *. To measure the changes in R eff, we combined a high voltage source/measure unit with the existing AFAM system. The data obtained showed that the phase transformation from Si-I to Si-II is preceded by other structural changes such as formation of distorted diamond structures and formation of Si-III. This conclusion was reached after observing a small hysteretic behavior in the load-unload stiffness curve accompanied by only very small changes in the resistance of the tip-sample system occurring on the unloading. The coinciding of a sudden increase in the values of the contact stiffness with a decrease in the resistance of the system indicated that the formation of metallic Si-II occurred in the subsequent measurements. The interpretation of our results found confirmation in the results of molecular dynamics and atomistic simulations performed for silicon under nanoindentation experiments.

  15. Standard Sine Fitting Algorithms Applied To Blade Tip Timing Data

    Directory of Open Access Journals (Sweden)

    Kaźmierczak Krzysztof

    2014-12-01

    Full Text Available Blade Tip Timing (BTT is a non-intrusive method to measure blade vibration in turbomachinery. Time of Arrival (TOA is recorded when a blade is passing a stationary sensor. The measurement data, in form of undersampled (aliased tip-deflection signal, are difficult to analyze with standard signal processing methods like digital filters or Fourier Transform. Several indirect methods are applied to process TOA sequences, such as reconstruction of aliased spectrum and Least-Squares Fitting to harmonic oscillator model. We used standard sine fitting algorithms provided by IEEE-STD-1057 to estimate blade vibration parameters. Blade-tip displacement was simulated in time domain using SDOF model, sampled by stationary sensors and then processed by the sinefit.m toolkit. We evaluated several configurations of different sensor placement, noise level and number of data. Results of the linear sine fitting, performed with the frequency known a priori, were compared with the non-linear ones. Some of non-linear iterations were not convergent. The algorithms and testing results are aimed to be used in analysis of asynchronous blade vibration.

  16. Remote Electromagnetic Vibration of Steerable Needles for Imaging in Power Doppler Ultrasound

    Science.gov (United States)

    Cabreros, Sarah S.; Jimenez, Nina M.; Greer, Joseph D.; Adebar, Troy K.; Okamura, Allison M.

    2015-01-01

    Robotic needle steering systems for minimally invasive medical procedures require complementary medical imaging systems to track the needles in real time. Ultrasound is a promising imaging modality because it offers relatively low-cost, real-time imaging of the needle. Previous methods applied vibration to the base of the needle using a voice coil actuator, in order to make the needle visible in power Doppler ultrasound. We propose a new method for needle tip vibration, using electromagnetic actuation of small permanent magnets placed inside the needle to improve needle tip visibility in power Doppler imaging. Robotic needle insertion experiments using artificial tissue and ex vivo porcine liver showed that the electromagnetic tip vibration method can generate a stronger Doppler response compared to the previous base vibration method, resulting in better imaging at greater needle depth in tissue. It also eliminates previous issues with vibration damping along the shaft of the needle. PMID:26413379

  17. Urban vibrations

    DEFF Research Database (Denmark)

    Morrison, Ann; Knudsen, L.; Andersen, Hans Jørgen

    2012-01-01

      lab   studies   in   that   we   found   a   decreased   detection   rate   in   busy   environments.   Here   we   test   with   a   much   larger   sample   and   age   range,   and   contribute   with   the   first   vibration  sensitivity  testing  outside  the  lab  in  an  urban   public...

  18. Mechanochemistry Induced Using Force Exerted by a Functionalized Microscope Tip

    DEFF Research Database (Denmark)

    Zhang, Yajie; Wang, Yongfeng; Lü, Jing-Tao

    2017-01-01

    Atomic-scale mechanochemistry is realized from force exerted by a C60 -functionalized scanning tunneling microscope tip. Two conformers of tin phthalocyanine can be prepared on coinage-metal surfaces. A transition between these conformers is induced on Cu(111) and Ag(100). Density-functional calc......Atomic-scale mechanochemistry is realized from force exerted by a C60 -functionalized scanning tunneling microscope tip. Two conformers of tin phthalocyanine can be prepared on coinage-metal surfaces. A transition between these conformers is induced on Cu(111) and Ag(100). Density...

  19. Pressure dependence of the elastic constants and vibrational anharmonicity of Pd sub 3 sub 9 Ni sub 1 sub 0 Cu sub 3 sub 0 P sub 2 sub 1 bulk metallic glass

    CERN Document Server

    Wang Li; Sun, L L; Wang, W H; Wang, W K

    2003-01-01

    The pressure dependence of the acoustic velocities of a Pd sub 3 sub 9 Ni sub 1 sub 0 Cu sub 3 sub 0 P sub 2 sub 1 bulk metallic glass have been investigated up to 0.5 GPa at room temperature with the pulse echo overlap method. Two independent second-order elastic coefficients C sub 1 sub 1 and C sub 4 sub 4 and their pressure derivatives are yielded. The vibrational anharmonicity is shown by calculating both the acoustic mode Grueneisen parameters in the long-wavelength limit and the thermal Grueneisen parameter, and this result is compared with that for the Pd sub 4 sub 0 Ni sub 4 sub 0 P sub 2 sub 0 bulk glass.

  20. Magnetic nondestructive testing of rotor blade tips

    Science.gov (United States)

    Cardelli, E.; Faba, A.; Marsili, R.; Rossi, G.; Tomassini, R.

    2015-05-01

    This paper deals with a particular magnetic nondestructive technique applied to the control of the position of the steel blades in rotating parts of turbines and engines. The working principle is based on a bridge of four identical magneto-resistive sensors. One sensor is placed near the blades, and the change in magnetic field produced by a permanent magnet and deviated by the change in position of the blade is detected by the sensor bridge. The position of the sensor is indicated, via dedicated FEM simulations, in order to have high sensitivity to the position change and high output signal. The accuracy and effectiveness of the proposed method are shown by experimental tests carried out in our laboratories. In particular, the tests indicate that the proposed magnetic nondestructive technique can be used in an almost large velocity range, and for quite different values of blade tip. The method seems also promising for the detection of blade vibrations.

  1. Tipping point leadership.

    Science.gov (United States)

    Kim, W Chan; Mauborgne, Renée

    2003-04-01

    When William Bratton was appointed police commissioner of New York City in 1994, turf wars over jurisdiction and funding were rife and crime was out of control. Yet in less than two years, and without an increase in his budget, Bratton turned New York into the safest large city in the nation. And the NYPD was only the latest of five law-enforcement agencies Bratton had turned around. In each case, he succeeded in record time despite limited resources, a demotivated staff, opposition from powerful vested interests, and an organization wedded to the status quo. Bratton's turnarounds demonstrate what the authors call tipping point leadership. The theory of tipping points hinges on the insight that in any organization, fundamental changes can occur quickly when the beliefs and energies of a critical mass of people create an epidemic movement toward an idea. Bratton begins by overcoming the cognitive hurdles that block organizations from recognizing the need for change. He does this by putting managers face-to-face with operational problems. Next, he manages around limitations on funds, staff, or equipment by concentrating resources on the areas that are most in need of change and that have the biggest payoffs. He meanwhile solves the motivation problem by singling out key influencers--people with disproportionate power due to their connections or persuasive abilities. Finally, he closes off resistance from powerful opponents. Not every CEO has the personality to be a Bill Bratton, but his successes are due to much more than his personality. He relies on a remarkably consistent method that any manager looking to turn around an organization can use to overcome the forces of inertia and reach the tipping point.

  2. Theory of vibration protection

    CERN Document Server

    Karnovsky, Igor A

    2016-01-01

    This text is an advancement of the theory of vibration protection of mechanical systems with lumped and distributed parameters. The book offers various concepts and methods of solving vibration protection problems, discusses the advantages and disadvantages of different methods, and the fields of their effective applications. Fundamental approaches of vibration protection, which are considered in this book, are the passive, parametric and optimal active vibration protection. The passive vibration protection is based on vibration isolation, vibration damping and dynamic absorbers. Parametric vibration protection theory is based on the Shchipanov-Luzin invariance principle. Optimal active vibration protection theory is based on the Pontryagin principle and the Krein moment method. The book also contains special topics such as suppression of vibrations at the source of their occurrence and the harmful influence of vibrations on humans. Numerous examples, which illustrate the theoretical ideas of each chapter, ar...

  3. The Investigations of Friction under Die Surface Vibration in Cold Forging Process

    DEFF Research Database (Denmark)

    Jinming, Sha

    The objective of this thesis is to fundamentally study the influence of die surface vibration on friction under low frequency in metal forging processes. The research includes vibrating tool system design for metal forming, theoretical and experimental investigations, and finite element simulations...... on die surface vibration in forging process. After a general introduction to friction mechanisms and friction test techniques in metal forming, the application of ultrasonic vibration in metal forming, the influence of sliding velocity on friction is described. Some earlier investigations...... is undergoing vibration. In the experiments, die surface orientation, frequency and amplitude of vibration, vibrating wave form and the direction of vibration has been taken into account as the parameters which influence friction behaviour in forging process. The results reveal that friction could be reduced up...

  4. AERODYNAMICS OF WING TIP SAILS

    Directory of Open Access Journals (Sweden)

    MUSHTAK AL-ATABI

    2006-06-01

    Full Text Available Observers have always been fascinated by soaring birds. An interesting feature of these birds is the existence of few feathers extending from the tip of the wing. In this paper, small lifting surfaces were fitted to the tip of a NACA0012 wing in a fashion similar to that of wing tip feathers. Experimental measurements of induced drag, longitudinal static stability and trailing vortex structure were obtained.The tests showed that adding wing tip surfaces (sails decreased the induced drag factor and increased the longitudinal static stability. Results identified two discrete appositely rotated tip vortices and showed the ability of wing tip surfaces to break them down and to diffuse them.

  5. Tipping: The Economics of a Social Norm

    OpenAIRE

    Ofer H. Azar

    2003-01-01

    Tipping illustrates the importance of social norms in motivating economic behavior. People tip because this is the social norm and disobeying norms results in social disapproval that creates emotional disutility. Tipping is also economically important: in the United States alone, millions of workers derive most of their income from tips, and annual tips amount to dozens of billions of dollars. I claim that tipping is not a single phenomenon; the economics of some tipping occasions is very dif...

  6. Plasmonic focusing of infrared SNOM tip patterned with asymmetric structures.

    Science.gov (United States)

    Qian, Qinbai; Yu, Haochi; Gou, Peng; Xu, Jie; An, Zhenghua

    2015-05-18

    Several scattering type metal tips patterned with asymmetric metal/dielectric bump gratings are studied and proved to be efficient in focusing light energy into nano 'hot spot'. The dielectric bump tip shows complex mechanisms including local geometric resonance, surface plasmon polariton (SPP) standing wave resonance and Fano effect in the near-field enhancement. Additionally, considering the practical situation, we also demonstrate that, for the case of bending tip surface, the grating coupling method for plasmonic nano-focusing is still applicable if the intervals between neighboring bumps are well designed according to the surface bending curvature. With practical realizations, our results could benefit not only infrared scanning near-field optical microscopes (SNOMs) but also many other applications in nanotechnology such as sensing and lithography.

  7. Effect of post length and type of luting agent on the dislodging time of metallic prefabricated posts by using ultrasonic vibration.

    Science.gov (United States)

    Ebrahimi Dastgurdi, Maziar; Khabiri, Masud; Khademi, Abbasali; Zare Jahromi, Maryam; Hosseini Dastnaei, Peimaneh

    2013-11-01

    The purpose of this study was to determine and compare the times needed to dislodge prefabricated titanium posts of different luting lengths with various cements. Eighty-one intact extracted, single-canal human teeth were selected and endodontically treated. Specimens were randomly divided into 9 groups, which were arranged according to the post space length (5, 7, and 9 mm) and cement type (zinc phosphate, glass ionomer, and resin cement). Titanium posts were cemented into the post spaces, and after 1 week of storage they were subjected to ultrasonic vibration. The dislodging times were recorded and analyzed by using the Kruskal-Wallis and Mann-Whitney tests (P ultrasonic device. Copyright © 2013 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  8. Catalyzed hydrogenation of nitrogen and ethylene on metal (Fe, Pt) single crystal surfaces and effects of coadsorption: A sum frequency generation vibrational spectroscopy study

    Energy Technology Data Exchange (ETDEWEB)

    Westerberg, Staffan Per Gustav [Univ. of California, Berkeley, CA (United States)

    2004-01-01

    High-pressure catalytic reactions and associated processes, such as adsorption have been studied on a molecular level on single crystal surfaces. Sum Frequency Generation (SFG) vibrational spectroscopy together with Auger Electron Spectroscopy (AES), Temperature Programmed Desorption (TPD) and Gas Chromatography (GC) were used to investigate the nature of species on catalytic surfaces and to measure the catalytic reaction rates. Special attention has been directed at studying high-pressure reactions and in particular, ammonia synthesis in order to identify reaction intermediates and the influence of adsorbates on the surface during reaction conditions. The adsorption of gases N2, H2, O2 and NH3 that play a role in ammonia synthesis have been studied on the Fe(111) crystal surface by sum frequency generation vibrational spectroscopy using an integrated Ultra-High Vacuum (UHV)/high-pressure system. SFG spectra are presented for the dissociation intermediates, NH2 (~3325 cm-1) and NH (~3235 cm-1) under high pressure of ammonia (200 Torr) on the clean Fe(111) surface. Addition of 0.5 Torr of oxygen to 200 Torr of ammonia does not significantly change the bonding of dissociation intermediates to the surface. However, it leads to a phase change of nearly 180° between the resonant and non-resonant second order non-linear susceptibility of the surface, demonstrated by the reversal of the SFG spectral features. Heating the surface in the presence of 200 Torr ammonia and 0.5 Torr oxygen reduces the oxygen coverage, which can be seen from the SFG spectra as another relative phase change of 180°. The reduction of the oxide is also supported by Auger electron spectroscopy. The result suggests that the phase change of the spectral features could serve as a sensitive indicator of the chemical environment of the adsorbates.

  9. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

    Medline Plus

    Full Text Available ... Images/Videos About Us News Physician Resources Professions Site Index A-Z Transjugular Intrahepatic Portosystemic Shunt (TIPS) Transjugular Intrahepatic Portosystemic Shunt or TIPS is a procedure that uses imaging guidance to connect the portal vein to the hepatic vein in the liver. ...

  10. TUBULARIZED INCISED PLATE (TIP) URETHROPLASTY:

    African Journals Online (AJOL)

    Objective: Recently, tubularized incised plate. (TIP) urethroplasty (Snodgrass repair) has gained popularity for the primary repair of distal and proximal hypospadias. This study was carried out to evaluate TIP urethro- plasty in the repair of failed and compli- cated hypospadias cases. Patients and Methods: This study was ...

  11. No-Fad Diet Tips

    Science.gov (United States)

    ... Works Healthy Workplace Food and Beverage Toolkit No-Fad Diet Tips Updated:Oct 18,2016 Tips - Think Smart: ... adapted with permission from American Heart Association No-Fad Diet: A Personal Plan for Healthy Weight Loss , Copyright © ...

  12. Choking and Strangulation Prevention Tips

    Science.gov (United States)

    ... Blog Videos Newsletter facebook twitter instagram pinterest gplus youtube Search Menu Why It Matters Who We Are What We Do Find Your Safe Kids Safe Kids Day Main menu Keeping All Kids Safe Safety Tips Get Involved 4 Star Charity Donate Safety Tips Age Group Babies 0–12 Months Little Kids 1– ...

  13. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

    Medline Plus

    Full Text Available ... liver disease are at greater risk for worsening liver failure after TIPS. If your liver failure is severe, a TIPS may not be the ... children are more likely to be performed before liver transplant in those with ascites or variceal ... 08, 2017 Send us your feedback Did you find the ...

  14. Nanoscale piezoelectric vibration energy harvester design

    Science.gov (United States)

    Foruzande, Hamid Reza; Hajnayeb, Ali; Yaghootian, Amin

    2017-09-01

    Development of new nanoscale devices has increased the demand for new types of small-scale energy resources such as ambient vibrations energy harvesters. Among the vibration energy harvesters, piezoelectric energy harvesters (PEHs) can be easily miniaturized and fabricated in micro and nano scales. This change in the dimensions of a PEH leads to a change in its governing equations of motion, and consequently, the predicted harvested energy comparing to a macroscale PEH. In this research, effects of small scale dimensions on the nonlinear vibration and harvested voltage of a nanoscale PEH is studied. The PEH is modeled as a cantilever piezoelectric bimorph nanobeam with a tip mass, using the Euler-Bernoulli beam theory in conjunction with Hamilton's principle. A harmonic base excitation is applied as a model of the ambient vibrations. The nonlocal elasticity theory is used to consider the size effects in the developed model. The derived equations of motion are discretized using the assumed-modes method and solved using the method of multiple scales. Sensitivity analysis for the effect of different parameters of the system in addition to size effects is conducted. The results show the significance of nonlocal elasticity theory in the prediction of system dynamic nonlinear behavior. It is also observed that neglecting the size effects results in lower estimates of the PEH vibration amplitudes. The results pave the way for designing new nanoscale sensors in addition to PEHs.

  15. Nanoscale piezoelectric vibration energy harvester design

    Directory of Open Access Journals (Sweden)

    Hamid Reza Foruzande

    2017-09-01

    Full Text Available Development of new nanoscale devices has increased the demand for new types of small-scale energy resources such as ambient vibrations energy harvesters. Among the vibration energy harvesters, piezoelectric energy harvesters (PEHs can be easily miniaturized and fabricated in micro and nano scales. This change in the dimensions of a PEH leads to a change in its governing equations of motion, and consequently, the predicted harvested energy comparing to a macroscale PEH. In this research, effects of small scale dimensions on the nonlinear vibration and harvested voltage of a nanoscale PEH is studied. The PEH is modeled as a cantilever piezoelectric bimorph nanobeam with a tip mass, using the Euler-Bernoulli beam theory in conjunction with Hamilton’s principle. A harmonic base excitation is applied as a model of the ambient vibrations. The nonlocal elasticity theory is used to consider the size effects in the developed model. The derived equations of motion are discretized using the assumed-modes method and solved using the method of multiple scales. Sensitivity analysis for the effect of different parameters of the system in addition to size effects is conducted. The results show the significance of nonlocal elasticity theory in the prediction of system dynamic nonlinear behavior. It is also observed that neglecting the size effects results in lower estimates of the PEH vibration amplitudes. The results pave the way for designing new nanoscale sensors in addition to PEHs.

  16. The Effect of Tool Dimension, Tool Overhang and Cutting Parameters Towards Tool Vibration and Surface Roughness on Turning Process

    Directory of Open Access Journals (Sweden)

    Zuingli Santo Bandaso

    2017-03-01

    Full Text Available Turning process is the removal of metal from the outer diameter of a rotating cylindrical workpiece. Turning is used to reduce the diameter of the workpiece, usually to a specified dimension, and to produce a smooth finish on the metal. This research investigates the effect of feed rate, spindle speed, tool overhang and tool dimensions toward vibration amplitude and surface roughness on turning process. This study uses both statistical and graphical analysis of the data collected. The experimentation was carried out on conventional lathe machine with straight turning operation. Material used as workpiece was St.60 carbon steel which was turned with HSS tool bit with the dimension of 3/8 Inches and ½ Inches. Cutting parameters varied by spindle speed, feed rate, and tool overhang, while the depth of cut is maintained at a depth of 0.5 mm. The vibration data of cutting tool obtained from a transducer (vibrometer mounted at a distance of 10 mm from the tip of the cutting tool during the cutting process takes place, whereas the surface roughness data obtained from measurements of surface roughness apparatus after turning process. The results showed that, The effect of feed rate, spindle speed, tool overhang, and tool dimension simultaneously towards vibration amplitude and surface roughness has a grater effects on the use of 3/8 inches cutting tool than ½ inches cutting tool. With the use of the same tool dimensions obtained that, The most influential parameters on the vibration amplitude is tool overhang while the most influential parameter on surface roughness value is feed rate.

  17. Torsional Phacoemulsification and Tip Selection

    Directory of Open Access Journals (Sweden)

    Fırat Helvacıoğlu

    2014-10-01

    Full Text Available One of the recent advances in cataract surgery is torsional phacoemulsification. It was developed to increase the efficacy of ultrasonic emulsification. In torsional phacoemulsification, the torsional movement of the tip is translated to side-to-side cutting action with the aid of bent phaco tips. Lens material is cut in both directions, rather than only during a forward stroke. The efficiency of this technique is further enhanced by an improvement in followability provided by the inherent non-repulsive nature of the side-to-side motion. Tip selection is very important for the efficiency of torsional phacoemulsification. Theoretically, there are 2 ways to enhance the cutting efficiency of the tip. First is the stroke length; the 22-degree bent 30-degree Kelman mini-flared tip cuts longer than the 12-degree bent 30-degree mini-flared Kelman tip. Second is the angulation or bevel; the higher the degree (45 degrees, the better cutting efficiency. Retrospective analyses of the previously published clinical studies clearly demonstrated that the efficacy of the torsional phacoemulsification has positive correlation with both the aperture angles and neck angles of the tips. (Turk J Ophthalmol 2014; 44: 392-5

  18. Piezoelectric nonlinear vibration focusing on the second-harmonic vibration mode.

    Science.gov (United States)

    Ozaki, Ryohei; Liu, Yaoyang; Hosaka, Hiroshi; Morita, Takeshi

    2018-01-01

    Resonant piezoelectric devices are driven under high power condition. In such condition, a nonlinear piezoelectric vibration becomes apparent and this nonlinearity should be taken into account in the design procedure using the finite elemental method (FEM). The purpose of this study is to introduce the nonlinear parameter to the FEM and to establish the method for measuring the nonlinear parameter through evaluating a nonlinear model for a piezoelectric vibration. In a previous study about the nonlinear piezoelectric vibration, the third term was mainly focused on because the third mode vibration affects the fundamental vibration in the case of a simple bar-type transducer. On the other hand, we considered the second nonlinear parameter of the compliance to the piezoelectric constitutive equation. We observed that this parameter affects the vibration amplitude with each position and the velocity at the tip of the transducer with a double frequency at resonant. It was confirmed that two measured nonlinear parameters based on these two relationships were almost same. From these values, we concluded that the proposed model is reasonable. Copyright © 2017. Published by Elsevier B.V.

  19. Electrochemical etching of sharp tips for STM reveals singularity

    DEFF Research Database (Denmark)

    Quaade, Ulrich; Oddershede, Lene

    2002-01-01

    Electrochemical etching of metal wires is widely used to produce atomically sharp tips for use in scanning tunneling microscopy (STM). In this letter we uncover the existence of a finite-time singularity in the process: Several of the physical parameters describing the system exhibit scaling...... towards and away from a particular singular point in time, exactly the time at which the wire breaks. The obtained scaling exponents coincide with exponents reported from other singular dynamical systems. The results also provide knowledge of how to control STM tip properties on the nano-scale....

  20. Vibrational lineshapes of adsorbates on solid surfaces

    Science.gov (United States)

    Ueba, H.

    A review is presented of the current activity in vibrational spectroscopy of adsorbates on metal surfaces. A brief introduction of the representative spectroscopies is given to demonstrate the rich information contained in vibrational spectra, which are characterized by their intensity, peak position and width. Analysis of vibrational spectra enables us to gain the deep insight into not only the local character of adsorption site or geometry, but also the dynamical interaction between the adsorbates or between the adsorbate and the substrate. Some recent instructive experimental results, mostly of a CO molecule adsorbed on various metal surfaces, are accompanied by the corresponding theoretical recipe for vibrational excitation mechanisms. Wide spread experimental results of the C-O stretching frequency of CO adsorbed on metal surfaces are discussed in terms of the chemical effect involving the static and dynamic charge transfers between the chemisorbed CO and metal, and also of the electrostatic dipole-dipole interaction between the molecules. The central subject of this review is directed to the linshapes characterized by the vibrational relaxation processes of adsorbates. A simple and transparent model is introduced to show that the characteristic decay time of the correlation function for the vibrational coordinates is the key quantity to determine the spectral lineshapes. Recent experimental results focused on a search for an intrinsic broadening mechanism are reviewed in the light of the so-called T1 (energy) and T2 (phase) relaxation processesof the vibrational excited states of adsorbates. Those are the vibrational energy dissipation into the elementary excitation, such as phonons or electron-hole pairs in the metal substrate, and pure dephasing due to the energy exchange with the sorroundings. The change of width and frequency by varying the experimental variables, such as temperature or isotope effect, provides indispensable knowledge for the dynamical

  1. Vibrational coupling in plasmonic molecules.

    Science.gov (United States)

    Yi, Chongyue; Dongare, Pratiksha D; Su, Man-Nung; Wang, Wenxiao; Chakraborty, Debadi; Wen, Fangfang; Chang, Wei-Shun; Sader, John E; Nordlander, Peter; Halas, Naomi J; Link, Stephan

    2017-10-31

    Plasmon hybridization theory, inspired by molecular orbital theory, has been extremely successful in describing the near-field coupling in clusters of plasmonic nanoparticles, also known as plasmonic molecules. However, the vibrational modes of plasmonic molecules have been virtually unexplored. By designing precisely configured plasmonic molecules of varying complexity and probing them at the individual plasmonic molecule level, intramolecular coupling of acoustic modes, mediated by the underlying substrate, is observed. The strength of this coupling can be manipulated through the configuration of the plasmonic molecules. Surprisingly, classical continuum elastic theory fails to account for the experimental trends, which are well described by a simple coupled oscillator picture that assumes the vibrational coupling is mediated by coherent phonons with low energies. These findings provide a route to the systematic optical control of the gigahertz response of metallic nanostructures, opening the door to new optomechanical device strategies. Published under the PNAS license.

  2. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

    Medline Plus

    Full Text Available ... the TIPS. top of page Additional Information and Resources Society of Interventional Radiology (SIR) - Patient Center This ... here Images × Image Gallery Radiologist and patient consultation. View full size with caption Pediatric Content Some imaging ...

  3. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

    Medline Plus

    Full Text Available ... who typically need a TIPS have portal hypertension , meaning they have increased pressure in the portal vein ... community, you can search the ACR-accredited facilities database . This website does not provide cost information. The ...

  4. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

    Medline Plus

    Full Text Available ... that would ordinarily pass through the liver to bypass the liver entirely, reducing high blood pressure in ... same physiological results as a surgical shunt or bypass, without the risks that accompany open surgery. TIPS ...

  5. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

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    Full Text Available ... blood draining from the bowel back to the heart while avoiding the liver. TIPS may successfully reduce ... blood away from the liver back to the heart). A stent is then placed in this tunnel ...

  6. Dining Out Tips by Cuisine

    Science.gov (United States)

    ... Preschoolers Infographic How to Make a Healthy Home Dietary Recommendations for Healthy Children Top 10 Tips to Help Children Develop Healthy Habits Fruit and Veggie Toolkit for Kids Healthy Foods ...

  7. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

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    Full Text Available ... surgery. Your TIPS should have less of an effect than open surgical bypass on future liver transplantation ... Encephalopathy can be treated with certain medications, a special diet or, by revising the stent, but sometimes ...

  8. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

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    Full Text Available ... pressure. top of page How does the procedure work? A TIPS reroutes blood flow in the liver ... complications, reported in fewer than five percent of cases, may include: occlusion, or complete blockage, of the ...

  9. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

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    Full Text Available ... the limitations of TIPS? Patients with more advanced liver disease are at greater risk for worsening liver failure ... patient who already has encephalopathy because of their liver disease may not be a good candidate for the ...

  10. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

    Medline Plus

    Full Text Available ... local anesthetic medications, general anesthesia or to contrast materials containing iodine (sometimes referred to as "dye" or " ... the placement of the TIPS stent, a contrast material will be injected in the hepatic vein to ...

  11. Tips for Relieving Dry Skin

    Science.gov (United States)

    ... skin include lactic acid, urea, hyaluronic acid, dimethicone, glycerin, lanolin, mineral oil, and petrolatum. Tip: Carry a ... using: Deodorant soaps Skin care products that contain alcohol, fragrance, retinoids, or alpha-hydroxy acid (AHA) Avoiding ...

  12. Tips to Prevent Tick Bites

    Science.gov (United States)

    Using the right insect repellent and other preventive actions can discourage ticks, mosquitoes, and other biting insects from landing on you. Tips include avoiding tick habitats and minimizing exposed skin.

  13. Tips to Prevent Mosquito Bites

    Science.gov (United States)

    Using the right insect repellent and other preventive actions can discourage mosquitoes from landing on you. Tips include removing mosquito habitats such as standing water, minimizing exposed skin, and staying indoors while mosquitoes are most active.

  14. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

    Medline Plus

    Full Text Available ... Patients who typically need a TIPS have portal hypertension , meaning they have increased pressure in the portal ... leading to cirrhosis (scarring of the liver). Portal hypertension can also occur in children, although children are ...

  15. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

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    Full Text Available ... pressure. top of page How does the procedure work? A TIPS reroutes blood flow in the liver ... physician will numb an area just above your right collarbone with a local anesthetic . A very small ...

  16. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

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    Full Text Available ... anti-inflammatory drugs (NSAIDs) or blood thinners several days prior to your procedure and instructed to not ... overnight at the hospital for one or more days. What is Transjugular Intrahepatic Portosystemic Shunt (TIPS)? What ...

  17. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

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    Full Text Available ... liver back to the heart. top of page How should I prepare? You should report to your ... heart beat and blood pressure. top of page How does the procedure work? A TIPS reroutes blood ...

  18. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

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    Full Text Available ... the liver to the heart). A stent placed inside this pathway keeps it open and allows some ... keeps the shunt open (TIPS) is contained entirely inside the diseased liver, and is removed with it ...

  19. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

    Medline Plus

    Full Text Available ... the skin is a rare complication (it may happen in complex and lengthy procedures requiring ... risk for worsening liver failure after TIPS. If your liver failure is severe, a ...

  20. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

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    Full Text Available ... TIPS may successfully reduce internal bleeding in the stomach and esophagus in patients with cirrhosis. Tell your ... the liver into the veins of the spleen, stomach, lower esophagus, and intestines, causing enlarged vessels, bleeding ...

  1. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

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    Full Text Available ... in creating the TIPS. top of page Additional Information and Resources Society of Interventional Radiology (SIR) - Patient ... Send us your feedback Did you find the information you were looking for? Yes No Please type ...

  2. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

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    Full Text Available ... in an hour or two but may take up to several hours depending on the complexity of ... normal activities in seven to 10 days. Follow-up ultrasounds will be performed frequently after the TIPS ...

  3. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

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    Full Text Available ... treatments. The greatest difference in performing TIPS in children is their tremendous variability in size, physiology, and medical diseases. This can result in significant challenges in creating ...

  4. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

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    Full Text Available ... through the TIPS. Pressure will be applied to prevent any bleeding and the opening in the skin ... are monitored in intensive care beforehand and during recovery. You should be able to resume your normal ...

  5. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

    Medline Plus

    Full Text Available ... to the heart while avoiding the liver. TIPS may successfully reduce internal bleeding in the stomach and ... conditions, allergies and medications you’re taking. You may be advised to stop taking aspirin, nonsteroidal anti- ...

  6. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

    Medline Plus

    Full Text Available ... while avoiding the liver. TIPS may successfully reduce internal bleeding in the stomach and esophagus in patients ... site. Using ultrasound, the doctor will identify your internal jugular vein , which is situated above your collarbone, ...

  7. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

    Medline Plus

    Full Text Available ... necessary, precautions will be taken to minimize radiation exposure to the baby. See the Safety page for ... surgery. Your TIPS should have less of an effect than open surgical bypass on future liver transplantation ...

  8. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

    Medline Plus

    Full Text Available ... pressure. top of page How does the procedure work? A TIPS reroutes blood flow in the liver ... blood pressure and pulse during the procedure. A nurse or technologist will insert an intravenous (IV) line ...

  9. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

    Medline Plus

    Full Text Available ... you are pregnant and discuss any recent illnesses, medical conditions, allergies and medications you’re taking. You ... with ascites or variceal bleeding resistant to traditional medical treatments. The greatest difference in performing TIPS in ...

  10. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

    Medline Plus

    Full Text Available ... top of page What are the benefits vs. risks? Benefits A TIPS is designed to produce the ... skin that does not have to be stitched. Risks Any procedure where the skin is penetrated carries ...

  11. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

    Medline Plus

    Full Text Available ... seen in adults, often as a result of chronic liver problems leading to cirrhosis (scarring of the ... limitations of TIPS? Patients with more advanced liver disease are at greater risk for worsening liver failure ...

  12. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

    Medline Plus

    Full Text Available ... system. This pressure buildup can cause blood to flow backward from the liver into the veins of ... does the procedure work? A TIPS reroutes blood flow in the liver and reduces abnormally high blood ...

  13. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

    Medline Plus

    Full Text Available ... story about radiology? Share your patient story here Images × Image Gallery Radiologist and patient consultation. View full size ... X-Ray and CT Exams Contrast Materials Venography Images related to Transjugular Intrahepatic Portosystemic Shunt (TIPS) Sponsored ...

  14. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

    Medline Plus

    Full Text Available ... X-Ray and CT Exams Contrast Materials Venography Images related to Transjugular Intrahepatic Portosystemic Shunt (TIPS) Sponsored by Please note RadiologyInfo.org is not a medical facility. Please contact your physician with specific medical ...

  15. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

    Medline Plus

    Full Text Available ... procedure? A TIPS is used to treat the complications of portal hypertension, including: variceal bleeding , bleeding from ... is taken to mitigate these risks. Other possible complications of the procedure include: fever muscle stiffness in ...

  16. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

    Medline Plus

    Full Text Available ... gained from the hepatic vein into the portal system using a TIPS needle (a special long needle ... may vary by geographic region. Discuss the fees associated with your prescribed ...

  17. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

    Medline Plus

    Full Text Available ... wear during the procedure. top of page What does the equipment look like? In this procedure, x- ... beat and blood pressure. top of page How does the procedure work? A TIPS reroutes blood flow ...

  18. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

    Medline Plus

    Full Text Available ... bear denotes child-specific content. Related Articles and Media Radiation Dose in X-Ray and CT Exams Contrast Materials Venography Images related to Transjugular Intrahepatic Portosystemic Shunt (TIPS) Sponsored ...

  19. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

    Medline Plus

    Full Text Available ... look like? In this procedure, x-ray or ultrasound equipment, a stent, and a balloon-tipped catheter ... over a table on which the patient lies. Ultrasound scanners consist of a console containing a computer ...

  20. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

    Medline Plus

    Full Text Available ... functions properly. top of page Who interprets the results and how do I get them? Prior to ... TIPS is designed to produce the same physiological results as a surgical shunt or bypass, without the ...

  1. Search Tips: MedlinePlus

    Science.gov (United States)

    ... of this page: https://medlineplus.gov/searchtips.html Search Tips To use the sharing features on this page, please enable JavaScript. How do I search MedlinePlus? The search box appears at the top ...

  2. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

    Medline Plus

    Full Text Available ... TIPS. top of page Additional Information and Resources Society of Interventional Radiology (SIR) - Patient Center This page ... American College of Radiology (ACR) and the Radiological Society of North America (RSNA), comprising physicians with expertise ...

  3. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

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    Full Text Available ... threatening and those patients are monitored in intensive care beforehand and during recovery. You should be able ... with ascites or variceal bleeding resistant to traditional medical treatments. The greatest difference in performing TIPS in ...

  4. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

    Medline Plus

    Full Text Available ... of page What are some common uses of the procedure? A TIPS is used to treat the ... during the procedure. top of page What does the equipment look like? In this procedure, x-ray ...

  5. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

    Medline Plus

    Full Text Available ... waves), as well as the type of body structure and composition of body tissue through which the ... the placement of the TIPS stent, a contrast material will be injected in the hepatic vein to ...

  6. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

    Medline Plus

    Full Text Available ... who typically need a TIPS have portal hypertension , meaning they have increased pressure in the portal vein ... of bleeding that can occur can sometimes be life threatening and those patients are monitored in intensive ...

  7. Tunable Passive Vibration Suppressor

    Science.gov (United States)

    Boechler, Nicholas (Inventor); Dillon, Robert Peter (Inventor); Daraio, Chiara (Inventor); Davis, Gregory L. (Inventor); Shapiro, Andrew A. (Inventor); Borgonia, John Paul C. (Inventor); Kahn, Daniel Louis (Inventor)

    2016-01-01

    An apparatus and method for vibration suppression using a granular particle chain. The granular particle chain is statically compressed and the end particles of the chain are attached to a payload and vibration source. The properties of the granular particles along with the amount of static compression are chosen to provide desired filtering of vibrations.

  8. Vibrations and Eigenvalues

    Indian Academy of Sciences (India)

    We make music by causing strings, membranes, or air columns to vibrate. Engineers design safe structures by control- ling vibrations. I will describe to you a very simple vibrating system and the mathematics needed to analyse it. The ideas were born in the work of Joseph-Louis Lagrange (1736–1813), and I begin by quot-.

  9. Computational Fluid Dynamic Analysis of a Vibrating Turbine Blade

    Directory of Open Access Journals (Sweden)

    Osama N. Alshroof

    2012-01-01

    Full Text Available This study presents the numerical fluid-structure interaction (FSI modelling of a vibrating turbine blade using the commercial software ANSYS-12.1. The study has two major aims: (i discussion of the current state of the art of modelling FSI in gas turbine engines and (ii development of a “tuned” one-way FSI model of a vibrating turbine blade to investigate the correlation between the pressure at the turbine casing surface and the vibrating blade motion. Firstly, the feasibility of the complete FSI coupled two-way, three-dimensional modelling of a turbine blade undergoing vibration using current commercial software is discussed. Various modelling simplifications, which reduce the full coupling between the fluid and structural domains, are then presented. The one-way FSI model of the vibrating turbine blade is introduced, which has the computational efficiency of a moving boundary CFD model. This one-way FSI model includes the corrected motion of the vibrating turbine blade under given engine flow conditions. This one-way FSI model is used to interrogate the pressure around a vibrating gas turbine blade. The results obtained show that the pressure distribution at the casing surface does not differ significantly, in its general form, from the pressure at the vibrating rotor blade tip.

  10. Comparison of different ultrasonic vibration modes for post removal.

    Science.gov (United States)

    Braga, Neilor Mateus Antunes; Silva, Juliana Monteiro da; Carvalho-Júnior, Jacy Ribeiro de; Ferreira, Raquel Conceição; Saquy, Paulo César; Brito-Júnior, Manoel

    2012-01-01

    This in vitro study compared different ultrasonic vibration modes for intraradicular cast post removal. The crowns of 24 maxillary canines were removed, the roots were embedded in acrylic resin blocks, and the canals were treated endodontically. The post holes were prepared and root canal impressions were taken with self-cured resin acrylic. After casting, the posts were cemented with zinc phosphate cement. The samples were randomly distributed into 3 groups (n=8): G1: no ultrasonic vibration (control); G2: tip of the ultrasonic device positioned perpendicularly to core surface and close to the incisal edge; and G3: tip of the ultrasonic device positioned perpendicularly to core surface at cervical region, close to the line of cementation. An Enac OE-5 ultrasound unit with an ST-09 tip was used. All samples were submitted to the tensile test using an universal testing machine at a crosshead speed of 1 mm/min. Data were subjected to one-way ANOVA and Tukey's post-hoc tests (α=0.05). Mean values of the load to dislodge the posts (MPa) were: G1 = 4.6 (± 1.4) A; G2 = 2.8 (± 0.9) B, and G3= 0.9 (± 0.3) C. Therefore, the ultrasonic vibration applied with the tip of device close to the core's cervical area showed higher ability to reduce the retention of cast post to root canal.

  11. Nonlinear Vibration of a Magnetic Spring

    Science.gov (United States)

    Zhong, Juhua; Cheng, Zhongqi; Ge, Ziming; Zhang, Yuelan; Lu, Wenqiang; Song, Feng; Li, Chuanyong

    2012-01-01

    To demonstrate the different vibration characteristics of a magnetic spring compared with those of a metal one, a magnetic spring apparatus was constructed from a pair of circular magnets of the same size with an inside diameter of 2.07 cm and an outside diameter of 4.50 cm. To keep the upper magnet in a suspension state, the two magnets were…

  12. Electronic and vibrational spectroscopy and vibrationally mediated photodissociation of V+(OCO).

    Science.gov (United States)

    Citir, Murat; Altinay, Gokhan; Metz, Ricardo B

    2006-04-20

    Electronic spectra of gas-phase V+(OCO) are measured in the near-infrared from 6050 to 7420 cm(-1) and in the visible from 15,500 to 16,560 cm(-1), using photofragment spectroscopy. The near-IR band is complex, with a 107 cm(-1) progression in the metal-ligand stretch. The visible band shows clearly resolved vibrational progressions in the metal-ligand stretch and rock, and in the OCO bend, as observed by Brucat and co-workers. A vibrational hot band gives the metal-ligand stretch frequency in the ground electronic state nu3'' = 210 cm(-1). The OCO antisymmetric stretch frequency in the ground electronic state (nu1'') is measured by using vibrationally mediated photodissociation. An IR laser vibrationally excites ions to nu1'' = 1. Vibrationally excited ions selectively dissociate following absorption of a second, visible photon at the nu1' = 1 CO2, due to interaction with the metal. Larger blue shifts observed for complexes with fewer ligands agree with trends seen for larger V+(OCO)n clusters.

  13. Optomechanical proposal for monitoring microtubule mechanical vibrations

    Science.gov (United States)

    Barzanjeh, Sh.; Salari, V.; Tuszynski, J. A.; Cifra, M.; Simon, C.

    2017-07-01

    Microtubules provide the mechanical force required for chromosome separation during mitosis. However, little is known about the dynamic (high-frequency) mechanical properties of microtubules. Here, we theoretically propose to control the vibrations of a doubly clamped microtubule by tip electrodes and to detect its motion via the optomechanical coupling between the vibrational modes of the microtubule and an optical cavity. In the presence of a red-detuned strong pump laser, this coupling leads to optomechanical-induced transparency of an optical probe field, which can be detected with state-of-the art technology. The center frequency and line width of the transparency peak give the resonance frequency and damping rate of the microtubule, respectively, while the height of the peak reveals information about the microtubule-cavity field coupling. Our method opens the new possibilities to gain information about the physical properties of microtubules, which will enhance our capability to design physical cancer treatment protocols as alternatives to chemotherapeutic drugs.

  14. Vibration analysis of cryocoolers

    Science.gov (United States)

    Tomaru, Takayuki; Suzuki, Toshikazu; Haruyama, Tomiyoshi; Shintomi, Takakazu; Yamamoto, Akira; Koyama, Tomohiro; Li, Rui

    2004-05-01

    The vibrations of Gifford-McMahon (GM) and pulse-tube (PT) cryocoolers were measured and analyzed. The vibrations of the cold-stage and cold-head were measured separately to investigate their vibration mechanisms. The measurements were performed while maintaining the thermal conditions of the cryocoolers at a steady state. We found that the vibration of the cold-head for the 4 K PT cryocooler was two orders of magnitude smaller than that of the 4 K GM cryocooler. On the other hand, the vibration of the cold-stages for both cryocoolers was of the same order of magnitude. From a spectral analysis of the vibrations and a simulation, we concluded that the vibration of the cold-stage is caused by an elastic deformation of the pulse tubes (or cylinders) due to the pressure oscillation of the working gas.

  15. Vibration analysis of cryocoolers

    Energy Technology Data Exchange (ETDEWEB)

    Tomaru, Takayuki; Suzuki, Toshikazu; Haruyama, Tomiyoshi; Shintomi, Takakazu; Yamamoto, Akira [High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki (Japan); Koyama, Tomohiro; Rui Li [Sumitomo Heavy Industries Ltd., Tokyo (Japan)

    2004-05-01

    The vibrations of Gifford-McMahon (GM) and pulse-tube (PT) cryocoolers were measured and analyzed. The vibrations of the cold-stage and cold-head were measured separately to investigate their vibration mechanisms. The measurements were performed while maintaining the thermal conditions of the cryocoolers at a steady state. We found that the vibration of the cold-head for the 4 K PT cryocooler was two orders of magnitude smaller than that of the 4 K GM cryocooler. On the other hand, the vibration of the cold-stages for both cryocoolers was of the same order of magnitude. From a spectral analysis of the vibrations and a simulation, we concluded that the vibration of the cold-stage is caused by an elastic deformation of the pulse tubes (or cylinders) due to the pressure oscillation of the working gas. (Author)

  16. Vibration of hydraulic machinery

    CERN Document Server

    Wu, Yulin; Liu, Shuhong; Dou, Hua-Shu; Qian, Zhongdong

    2013-01-01

    Vibration of Hydraulic Machinery deals with the vibration problem which has significant influence on the safety and reliable operation of hydraulic machinery. It provides new achievements and the latest developments in these areas, even in the basic areas of this subject. The present book covers the fundamentals of mechanical vibration and rotordynamics as well as their main numerical models and analysis methods for the vibration prediction. The mechanical and hydraulic excitations to the vibration are analyzed, and the pressure fluctuations induced by the unsteady turbulent flow is predicted in order to obtain the unsteady loads. This book also discusses the loads, constraint conditions and the elastic and damping characters of the mechanical system, the structure dynamic analysis, the rotor dynamic analysis and the system instability of hydraulic machines, including the illustration of monitoring system for the instability and the vibration in hydraulic units. All the problems are necessary for vibration pr...

  17. Molecular structure of the trans and cis isomers of metal-free phthalocyanine studied by gas-phase electron diffraction and high-level quantum chemical calculations: NH tautomerization and calculated vibrational frequencies.

    Science.gov (United States)

    Strenalyuk, Tatyana; Samdal, Svein; Volden, Hans Vidar

    2008-05-29

    The molecular structure of the trans isomer of metal-free phthalocyanine (H2Pc) is determined using the gas electron diffraction (GED) method and high-level quantum chemical calculations. B3LYP calculations employing the basis sets 6-31G**, 6-311++G**, and cc-pVTZ give two tautomeric isomers for the inner H atoms, a trans isomer having D2h symmetry and a cis isomer having C2v symmetry. The trans isomer is calculated to be 41.6 (B3LYP/6-311++G**, zero-point corrected) and 37.3 kJ/mol (B3LYP/cc-pVTZ, not zero-point corrected) more stable than the cis isomer. However, Hartree-Fock (HF) calculations using different basis sets predict that cis is preferred and that trans does not exist as a stable form of the molecule. The equilibrium composition in the gas phase at 471 degrees C (the temperature of the GED experiment) calculated at the B3LYP/6-311++G** level is 99.8% trans and 0.2% cis. This is in very good agreement with the GED data, which indicate that the mole fraction of the cis isomer is close to zero. The transition states for two mechanisms of the NH tautomerization have been characterized. A concerted mechanism where the two H atoms move simultaneously yields a transition state of D2h symmetry and an energy barrier of 95.8 kJ/mol. A two-step mechanism where a trans isomer is converted to a cis isomer, which is converted into another trans isomer, proceeds via two transition states of C(s) symmetry and an energy barrier of 64.2 kJ/mol according to the B3LYP/6-311++G** calculation. The molecular geometry determined from GED is in very good agreement with the geometry obtained from the quantum chemical calculations. Vibrational frequencies, IR, and Raman intensities have been calculated using B3LYP/6-311++G**. These calculations indicate that the molecule is rather flexible with six vibrational frequencies in the range of 20-84 cm(-1) for the trans isomer. The cis isomer might be detected by infrared matrix spectroscopy since the N-H stretching frequencies are

  18. Improved design for a low temperature scanning tunneling microscope with an in situ tip treatment stage

    Science.gov (United States)

    Kim, J.-J.; Joo, S. H.; Lee, K. S.; Yoo, J. H.; Park, M. S.; Kwak, J. S.; Lee, Jinho

    2017-04-01

    The Low Temperature Scanning Tunneling Microscope (LT-STM) is an extremely valuable tool not only in surface science but also in condensed matter physics. For years, numerous new ideas have been adopted to perfect LT-STM performances—Ultra-Low Vibration (ULV) laboratory and the rigid STM head design are among them. Here, we present three improvements for the design of the ULV laboratory and the LT-STM: tip treatment stage, sample cleaving stage, and vibration isolation system. The improved tip treatment stage enables us to perform field emission for the purpose of tip treatment in situ without exchanging samples, while our enhanced sample cleaving stage allows us to cleave samples at low temperature in a vacuum without optical access by a simple pressing motion. Our newly designed vibration isolation system provides efficient space usage while maintaining vibration isolation capability. These improvements enhance the quality of spectroscopic imaging experiments that can last for many days and provide increased data yield, which we expect can be indispensable elements in future LT-STM designs.

  19. Degassing of molten alloys with the assistance of ultrasonic vibration

    Science.gov (United States)

    Han, Qingyou; Xu, Hanbing; Meek, Thomas T.

    2010-03-23

    An apparatus and method are disclosed in which ultrasonic vibration is used to assist the degassing of molten metals or metal alloys thereby reducing gas content in the molten metals or alloys. High-intensity ultrasonic vibration is applied to a radiator that creates cavitation bubbles, induces acoustic streaming in the melt, and breaks up purge gas (e.g., argon or nitrogen) which is intentionally introduced in a small amount into the melt in order to collect the cavitation bubbles and to make the cavitation bubbles survive in the melt. The molten metal or alloy in one version of the invention is an aluminum alloy. The ultrasonic vibrations create cavitation bubbles and break up the large purge gas bubbles into small bubbles and disperse the bubbles in the molten metal or alloy more uniformly, resulting in a fast and clean degassing.

  20. Effect of vibration frequency on biopsy needle insertion force.

    Science.gov (United States)

    Tan, Lei; Qin, Xuemei; Zhang, Qinhe; Zhang, Hongcai; Dong, Hongjian; Guo, Tuodang; Liu, Guowei

    2017-05-01

    Needle insertion is critical in many clinical medicine procedures, such as biopsy, brachytherapy, and injection therapy. A platform with two degrees of freedom was set up to study the effect of vibration frequency on needle insertion force. The gel phantom deformation at the needle cutting edge and the Voigt model are utilized to develop a dynamic model to explain the relationship between the insertion force and needle-tip velocity. The accuracy of this model was verified by performing needle insertions into phantom gel. The effect of vibration on insertion force can be explained as the vibration increasing the needle-tip velocity and subsequently increasing the insertion force. In a series of needle insertion experiments with different vibration frequencies, the peak forces were selected for comparison to explore the effect of vibration frequency on needle insertion force. The experimental results indicate that the insertion force at 500Hz increases up to 17.9% compared with the force at 50Hz. Copyright © 2017 IPEM. Published by Elsevier Ltd. All rights reserved.

  1. Management of thumb tip injuries.

    Science.gov (United States)

    Germann, Günter; Sauerbier, Michael; Rudolf, Klaus D; Hrabowski, Manuel

    2015-03-01

    The management of thumb tip injuries has undergone great changes in recent years. The traditional armamentarium of flaps has been expanded and replaced by a wide variety of flaps with more versatility and less donor side morbidity. Parallel to the development of new flaps, the conservative treatment of thumb tip injuries with semi-occlusive dressing has gained ground in the treatment of these injuries. Although tedious and time-consuming, and requiring intensive communication with the patient to explain the look and occasionally fetid smell of the wound, this technique yields excellent results with respect to restoring contour and sensibility in pulp injuries. The article gives an update on the current options for treating thumb tip injuries including the most commonly applied flaps. Copyright © 2015 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

  2. Nanobits: customizable scanning probe tips

    DEFF Research Database (Denmark)

    Kumar, Rajendra; Shaik, Hassan Uddin; Sardan Sukas, Özlem

    2009-01-01

    We present here a proof-of-principle study of scanning probe tips defined by planar nanolithography and integrated with AFM probes using nanomanipulation. The so-called 'nanobits' are 2-4 mu m long and 120-150 nm thin flakes of Si3N4 or SiO2, fabricated by electron beam lithography and standard...... silicon processing. Using a microgripper they were detached from an array and fixed to a standard pyramidal AFM probe or alternatively inserted into a tipless cantilever equipped with a narrow slit. The nanobit-enhanced probes were used for imaging of deep trenches, without visible deformation, wear...... or dislocation of the tips of the nanobit after several scans. This approach allows an unprecedented freedom in adapting the shape and size of scanning probe tips to the surface topology or to the specific application....

  3. Spherical tuned liquid damper for vibration control in wind turbines

    DEFF Research Database (Denmark)

    Chen, Jun-Ling; Georgakis, Christos T.

    2015-01-01

    A tuned liquid damper (TLD), which consisted of two-layer hemispherical containers, partially filled with water, was investigated as a cost-effective method to reduce the wind-induced vibration of wind turbines. A 1/20 scaled test model was designed to investigate its performance on the shaking...... table. Three groups of equivalent ground accelerations were inputted to simulate the wind-induced dynamic response under different load cases. The influence of rotors and nacelle was assumed to be a concentrated tip mass. A series of free and forced vibration experiments were performed on the shaking...

  4. ZBrush Professional Tips and Techniques

    CERN Document Server

    Gaboury, Paul

    2012-01-01

    Learn to work effectively and creatively with all versions of ZBrush! ZBrush is used by top artists in Hollywood to model and sculpt characters in such films as Avatar, Iron Man, and Pirates of the Caribbean. In addition, this amazing technology is also used in jewelry design, forensic science, aerospace, video games, toy creation, and the medical field. Written by Pixologic's in-house ZBrush expert Paul Gaboury, this full-color, beautifully illustrated guide provides you with the ultimate tips and tricks to maximize your use of all versions of ZBrush. Reveals numerous little-known tips and tr

  5. Office 2010 Visual Quick Tips

    CERN Document Server

    Gunter, Sherry Kinkoph

    2010-01-01

    Get more done in Office 2010 in less time with these Quick Tips!. Whether you're new to Microsoft Office or updating from older versions, this is the perfect resource to get you quickly up to speed on Office 2010. Every application is covered, including Word, Excel, PowerPoint, Outlook, and Publisher. Full-color screenshots and numbered steps clearly explain dozens of features and functions-while quick shortcuts, tips, and tricks help you save time and boost productivity. You'll also find great new ways to access and use some Office apps right from the Web.: Walks you through dozens of new fea

  6. Ultrasonic-Assisted Incremental Microforming of Thin Shell Pyramids of Metallic Foil

    Directory of Open Access Journals (Sweden)

    Toshiyuki Obikawa

    2017-05-01

    Full Text Available Single point incremental forming is used for rapid prototyping of sheet metal parts. This forming technology was applied to the fabrication of thin shell micropyramids of aluminum, stainless steel, and titanium foils. A single point tool used had a tip radius of 0.1 mm or 0.01 mm. An ultrasonic spindle with axial vibration was implemented for improving the shape accuracy of micropyramids formed on 5–12 micrometers-thick aluminum, stainless steel, and titanium foils. The formability was also investigated by comparing the forming limits of micropyramids of aluminum foil formed with and without ultrasonic vibration. The shapes of pyramids incrementally formed were truncated pyramids, twisted pyramids, stepwise pyramids, and star pyramids about 1 mm in size. A much smaller truncated pyramid was formed only for titanium foil for qualitative investigation of the size reduction on forming accuracy. It was found that the ultrasonic vibration improved the shape accuracy of the formed pyramids. In addition, laser heating increased the forming limit of aluminum foil and it is more effective when both the ultrasonic vibration and laser heating are applied.

  7. Post-critical behavior of Beck`s column with a tip mass

    DEFF Research Database (Denmark)

    Andersen, S. B.; Thomsen, Jon Juel

    2002-01-01

    This study examines how a tip mass with rotary inertia affects the stability of a follower-loaded cantilevered column. Using nonlinear modeling and perturbation analysis, expressions are set up for determining the stability of the straight column and the amplitude of post-critical flutter...... oscillations. Bifurcation diagrams are given, showing how the vibration amplitude changes with follower load and other parameters. These results agree closely with numerical simulation. It is found that sufficiently large values of tip mass rotary inertia can change the primary bifurcation from supercritical...

  8. Nonlinear modeling of tuned liquid dampers (TLDs) in rotating wind turbine blades for damping edgewise vibrations

    DEFF Research Database (Denmark)

    Zhang, Zili; Nielsen, Søren R. K.; Basu, Biswajit

    2015-01-01

    Tuned liquid dampers (TLDs) utilize the sloshing motion of the fluid to suppress structural vibrations and become a natural candidate for damping vibrations in rotating wind turbine blades. The centrifugal acceleration at the tip of a wind turbine blade can reach a magnitude of 7–8g. This facilit......Tuned liquid dampers (TLDs) utilize the sloshing motion of the fluid to suppress structural vibrations and become a natural candidate for damping vibrations in rotating wind turbine blades. The centrifugal acceleration at the tip of a wind turbine blade can reach a magnitude of 7–8g...... free-surface elevation equally well, the one-mode model can still be utilized for the design of TLD. Parametric optimization of the TLD is carried out based on the one-mode model, and the optimized damper effectively improves the dynamic response of wind turbine blades....

  9. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

    Medline Plus

    Full Text Available Toggle navigation Test/Treatment Patient Type Screening/Wellness Disease/Condition Safety En Español More Info Images/Videos ... limitations of TIPS? Patients with more advanced liver disease are at greater risk for worsening liver failure ...

  10. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

    Medline Plus

    Full Text Available ... in creating the TIPS. top of page Additional Information and Resources Society of Interventional Radiology (SIR) - Patient Center This page ... of Use | Links | Site Map Copyright © 2018 ... To help ensure current and accurate information, we do not permit copying but encourage linking ...

  11. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

    Medline Plus

    Full Text Available ... liver to bypass the liver entirely, reducing high blood pressure in the portal vein and the associated risk of bleeding from enlarged veins. top of page How is the procedure performed? Image-guided, minimally invasive procedures such as a TIPS are most often ...

  12. Tipping points in ecological networks.

    Science.gov (United States)

    Tylianakis, Jason M; Coux, Camille

    2014-05-01

    Network studies have described the complex interactions among species. Concomitantly, researchers have searched for signals of ecosystem tipping points and attributes of systems that resist them. A recent study combines these areas, showing that attributes of pollination network structure delay critical transitions, and generating a wealth of new research questions. Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. Tips for Socializing with Aphasia

    Science.gov (United States)

    ... others get comfortable Dysarthria & Apraxia - How Stroke Affects Speech Auditory Overload Aphasia vs Apraxia Reading, Writing and Math Reading Rehab ( ... number of ways. Learn more about conditions impacting speech, language, reading and writing and find tips for continuing ... 7 Types of Aphasia 8 Brain Stem Stroke 9 Cognitive Challenges After ...

  14. Library Management Tips that Work

    Science.gov (United States)

    Smallwood, Carol, Ed.

    2011-01-01

    There's no shortage of library management books out there--but how many of them actually tackle the little details of day-to-day management, the hard-to-categorize things that slip through the cracks of a larger handbook? "Library Management Tips that Work" does exactly that, addressing dozens of such issues facing library managers, including: (1)…

  15. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

    Medline Plus

    Full Text Available ... Plan to stay overnight at the hospital for one or more days. What is Transjugular Intrahepatic Portosystemic Shunt (TIPS)? What are some common uses of the procedure? How should I prepare? What does the equipment look like? How does the procedure work? How is the procedure performed? What will I ...

  16. Field electron emission from a carbon-covered iridium tip

    Science.gov (United States)

    Bernatskii, D. P.; Pavlov, V. G.

    2017-11-01

    The formation of a carbon coating on an iridium field-emission electron emitter by benzene vapor pyrolysis has been studied. Processes on an emitting tip differ from those studied earlier on flat metal surfaces. The resulting coating either represents a monoatomic graphene film on the flat faces of the emitter or consists of graphene clusters. The field electron emission is localized on the edges and in the corners of a faceted graphite outgrowth. After alkali metals are adsorbed on the carbon coating, emissions from the flat faces anomalously grows and localizes on graphene-coated faces with alkali atoms present on the surface and under the graphene film.

  17. Mini-flared Kelman tip, reverse tip, and sidewinder tip with torsional phaco: a prospective randomized comparative study

    Directory of Open Access Journals (Sweden)

    Wilson Takashi Hida

    2015-02-01

    Full Text Available Purpose: To compare the efficiency of surgical procedures using three phaco tip designs in torsional phacoemulsification using the bevel-down technique. Methods: In this prospective, comparative, masked study, patients were randomly assigned to have torsional coaxial microincision cataract surgery using the mini-flared 45-degree Kelman tip, reversed mini-flared 30-degree Kelman tip, or Sidewinder 30-degree Kelman tip. Clinical measurements included preoperative and 3-month postoperative corrected distance visual acuity (CDVA, endothelial cell counts (ECC, and preoperative and 1-day postoperative central corneal thickness (CCT. Intraoperative measurements included phaco time, torsional time, aspiration time, case time, cumulative dissipated energy (CDE, and balanced salt solution volume (BSS. Results: The study evaluated 150 eyes of 150 patients. Intraoperatively, there was no statistically significant difference in cumulative dissipated energy, case time, torsional time, and aspiration time between the three tip configurations. However, less phaco time was used with the mini-flared 45-degree Kelman tip (p=0.02 than that with the Sidewinder 30-degree Kelman tip or reversed mini-flared 30-degree Kelman tip. The mini-flared 45-degree Kelman tip and the reversed mini-flared 30-degree Kelman tip required significantly less balanced salt solution volume than that required by the Sidewinder 30-degree Kelman tip (p=0.009. There was no statistically significant difference in corrected distance visual acuity and endothelial cell counts between tips 3 months postoperatively (p>0.05. Conclusion: All three tips were effective with no intraoperative complications. When using torsional phacoemulsification through microincisions and the prefracture technique with the bevel-down technique, the mini-flared 45-degree Kelman tip required a lower mean phaco time than the reversed mini-flared 30-degree Kelman tip and the Sidewinder 30-degree Kelman tip.

  18. Plasmonic Colloidal Nanoantennas for Tip-Enhanced Raman Spectrocopy

    Science.gov (United States)

    Dill, Tyler J.

    Plasmonic nanoantennas that a support localized surface plasmon resonance (LSPR) are capable of confining visible light to subwavelength dimensions due to strong electromagnetic field enhancement at the probe tip. Nanoantenna enable optical methods such as tip-enhanced Raman spectroscopy (TERS), a technique that uses scanning probe microscopy tips to provide chemical information with nanoscale spatial resolution and single-molecule sensitivities. The LSPR supported by the probe tip is extremely sensitive to the nanoscale morphology of the nanoantenna. Control of nanoscale morphology is notoriously difficult to achieve, resulting in TERS probes with poor reproducibility. In my thesis, I demonstrate high-performance, predictable, and broadband nanospectroscopy probes that are fabricated by self-assembly. Shaped metal nanoparticles are organized into dense layers and deposited onto scanning probe tips. When coupled to a metal substrate, these probes support a strong optical resonance in the gap between the substrate and the probe, producing dramatic field enhancements. I show through experiment and electromagnetic modeling that close-packed but electrically isolated nanoparticles are electromagnetically coupled. Hybridized LSPRs supported by self-assembled nanoparticles with a broadband optical response, giving colloidal nanoantenna a high tolerance for geometric variation resulting from fabrication. I find that coupled nanoparticles act as a waveguide, transferring energy from many neighboring nanoparticles towards the active TERS apex. I also use surface-enhanced Raman spectroscopy (SERS) to characterize the effects of nanoparticle polydispersity and gap height on the Raman enhancement. These colloidal probes have consistently achieved dramatic Raman enhancements in the range of 108-109 with sub-50 nm spatial resolution. Furthermore, in contrast to other nanospectroscopy probes, these colloidal probes can be fabricated in a scalable fashion with a batch

  19. Imaging performance comparison between CMOS and sCMOS detectors in a vibration test on large areas using digital holographic interferometry

    Science.gov (United States)

    Flores-Morenoa, J. M.; Torre I., Manuel H. De la; Aguayo, Daniel D.; Fernando Mendoza, S.

    2014-05-01

    A comparison of the interferometric imaging performance of two different cameras during a vibration study is presented. One of the cameras has a high speed CMOS sensor and the second one uses a high resolution (scientific) sCMOS sensor. This comparison is based on the interferometric response as a merit parameter of these sensors which is not a conventional procedure. Even when the current standard for image quality is on the signal to noise ratio calculations, an interferometric test to evaluate the fringe pattern visibility is equivalent to the contrast to noise ratio value. An out of plane digital holographic interferometer is used to test each camera once at the time with the same experimental conditions. The object under study is a metallically framed table with a Formica cover with an observable area of 1.1 m2. The sample is deformed by means of a controlled vibration induced by a tip ended linear step motor. Results from each camera are presented as the retrieved optical phase during the vibration. Finally, some conclusions based on the post processed images are presented suggesting a smoother optical phase obtained with the sCMOS camera.

  20. The effect of substrate on electric field enhancement of Tip-enhanced Raman spectroscopy (TERS)

    Science.gov (United States)

    Bahreini, Maryam

    2018-01-01

    The characterization of materials down to a few-molecule level is a key challenge in nanotechnology. Raman spectroscopy is a powerful method that provides chemical information via nondestructive vibrational fingerprinting. Unfortunately, this method suffers from signal weakness which prevents the study of small quantities. Tip-enhanced Raman spectroscopy (TERS) which combines the chemical sensitivity of Raman spectroscopy (RS) with high spatial resolution of scanning probe microscopy (SPM), provides chemical images of surfaces at the nanometer scale. In this method, irradiation of an SPM tip by a focused laser beam results in enhancement of local electric field via two reasons of localized surface plasmon resonance and lightning rod effect. This enhancement leads to the enhancement in Raman intensity from the sample surface in the vicinity of tip. In all TERS measurements, samples should be located on a substrate. In this paper, the dependence of the electric field enhancement to the substrate has been investigated. In simulations, three-dimensional finite-difference time-domain (3D-FDTD) method is used for numerical solution of Maxwell's equations. Our results show that the electric field enhancement is weak for the tip alone case. Introducing a substrate provides further electric field enhancement via near field electromagnetic dipole-dipole coupling between the tip and substrate. Since the side-illumination geometry is used for laser irradiation, the vertical component of the incident field plays a dominant role in the electric field enhancement. Therefore, the coupling effect between the tip and the substrate is the key contribution to the enhancement. For the case of silicon tip and the gold substrate, the electric field enhancement is improved considerably. There is an optimal tip size for TERS because of the competing effects of the radiation damping and the surface scattering of the tip. The results show the substrate as an effective tool for the

  1. Tips for Reducing Pesticide Impacts on Wildlife

    Science.gov (United States)

    This Web page provides tips for pesticide users in residential and agricultural settings, as well as tips for certified pesticide applicators for ways to protect wildlife from potentially harmful effects of pesticides.

  2. Helping Your Child: Tips for Parents

    Science.gov (United States)

    ... or computers. Use your children's food choices as teaching moments. Speak up when you see unhealthy eating ... Tips for Adults Health Tips for Older Adults Spanish-language publications in the Lifespan Series include the ...

  3. Parenting Tips: How to Improve Toddler Behavior

    Science.gov (United States)

    ... issues. To encourage listening and cooperation, follow these parenting tips. By Mayo Clinic Staff Life can be ... and a degree of routine. Consider these practical parenting tips. Make sure your displays of affection for ...

  4. Optimization design of high power ultrasonic circular ring radiator in coupled vibration.

    Science.gov (United States)

    Xu, Long; Lin, Shuyu; Hu, Wenxu

    2011-10-01

    This paper presents a new high power ultrasonic (HPU) radiator, which consists of a transducer, an ultrasonic horn, and a metal circular ring. Both the transducer and horn in longitudinal vibrations are used to drive a metal circular ring in a radial-axial coupled vibration. This coupled vibration cannot only generate ultrasound in both the radial and axial directions, but also focus the ultrasound inside the circular ring. Except for the radial-axial coupled vibration mode, the third longitudinal harmonic vibration mode with relative large vibration amplitude is also detected, which can be used as another operation mode. Overall, the HPU with these two vibration modes should have good potential to be applied in liquid processing, such as sonochemistry, ultrasonic cleaning, and Chinese herbal medicine extraction. Copyright © 2011 Elsevier B.V. All rights reserved.

  5. Model Indepedent Vibration Control

    OpenAIRE

    Yuan, Jing

    2010-01-01

    A NMIFC system is proposed for broadband vibration control. It has two important features. Feature F1 is that the NMIFC is stable without introducing any invasive effects, such as probing signals or controller perturbations, into the vibration system; feature F2 is

  6. Vibration Theory, Vol. 3

    DEFF Research Database (Denmark)

    Nielsen, Søren R. K.

    The present textbook has been written based on previous lecture notes for a course on stochastic vibration theory that is being given on the 9th semester at Aalborg University for M. Sc. students in structural engineering. The present 4th edition of this textbook on linear stochastic vibration...

  7. Vibration Theory, Vol. 3

    DEFF Research Database (Denmark)

    Nielsen, Søren R. K.

    The present textbook has been written based on previous lecture notes for a course on stochastic vibration theory that is being given on the 9th semester at Aalborg University for M. Sc. students in structural engineering. The present 2nd edition of this textbook on linear stochastic vibration...

  8. Hydroelastic Vibrations of Ships

    DEFF Research Database (Denmark)

    Jensen, Jørgen Juncher; Folsø, Rasmus

    2002-01-01

    A formula for the necessary hull girder bending stiffness required to avoid serious springing vibrations is derived. The expression takes into account the zero crossing period of the waves, the ship speed and main dimensions. For whipping vibrations the probability of exceedance for the combined...

  9. Gearbox vibration diagnostic analyzer

    Science.gov (United States)

    1992-01-01

    This report describes the Gearbox Vibration Diagnostic Analyzer installed in the NASA Lewis Research Center's 500 HP Helicopter Transmission Test Stand to monitor gearbox testing. The vibration of the gearbox is analyzed using diagnostic algorithms to calculate a parameter indicating damaged components.

  10. Mechanical vibration and shock analysis, sinusoidal vibration

    CERN Document Server

    Lalanne, Christian

    2014-01-01

    Everything engineers need to know about mechanical vibration and shock...in one authoritative reference work! This fully updated and revised 3rd edition addresses the entire field of mechanical vibration and shock as one of the most important types of load and stress applied to structures, machines and components in the real world. Examples include everything from the regular and predictable loads applied to turbines, motors or helicopters by the spinning of their constituent parts to the ability of buildings to withstand damage from wind loads or explosions, and the need for cars to m

  11. Radiofrequency Wire Recanalization of Chronically Thrombosed TIPS

    Energy Technology Data Exchange (ETDEWEB)

    Majdalany, Bill S., E-mail: bmajdala@med.umich.edu [University of Michigan Health System, Division of Interventional Radiology, Department of Radiology (United States); Elliott, Eric D., E-mail: eric.elliott@osumc.edu [The Ohio State University Wexner Medical Center, Division of Interventional Radiology, Department of Radiology (United States); Michaels, Anthony J., E-mail: Anthony.michaels@osumc.edu; Hanje, A. James, E-mail: James.Hanje@osumc.edu [The Ohio State University Wexner Medical Center, Division of Gastroenterology and Hepatology, Department of Medicine (United States); Saad, Wael E. A., E-mail: wsaad@med.umich.edu [University of Michigan Health System, Division of Interventional Radiology, Department of Radiology (United States)

    2016-07-15

    Radiofrequency (RF) guide wires have been applied to cardiac interventions, recanalization of central venous thromboses, and to cross biliary occlusions. Herein, the use of a RF wire technique to revise chronically occluded transjugular intrahepatic portosystemic shunts (TIPS) is described. In both cases, conventional TIPS revision techniques failed to revise the chronically thrombosed TIPS. RF wire recanalization was successfully performed through each of the chronically thrombosed TIPS, demonstrating initial safety and feasibility in this application.

  12. Vibrations of rotating machinery

    CERN Document Server

    Matsushita, Osami; Kanki, Hiroshi; Kobayashi, Masao; Keogh, Patrick

    2017-01-01

    This book opens with an explanation of the vibrations of a single degree-of-freedom (dof) system for all beginners. Subsequently, vibration analysis of multi-dof systems is explained by modal analysis. Mode synthesis modeling is then introduced for system reduction, which aids understanding in a simplified manner of how complicated rotors behave. Rotor balancing techniques are offered for rigid and flexible rotors through several examples. Consideration of gyroscopic influences on the rotordynamics is then provided and vibration evaluation of a rotor-bearing system is emphasized in terms of forward and backward whirl rotor motions through eigenvalue (natural frequency and damping ratio) analysis. In addition to these rotordynamics concerning rotating shaft vibration measured in a stationary reference frame, blade vibrations are analyzed with Coriolis forces expressed in a rotating reference frame. Other phenomena that may be assessed in stationary and rotating reference frames include stability characteristic...

  13. Nasal tip sutures: Techniques and indications.

    Science.gov (United States)

    Cingi, Cemal; Muluk, Nuray Bayar; Ulusoy, Seçkin; Söken, Hakan; Altıntoprak, Niyazi; Şahin, Ethem; Ada, Servet

    2015-01-01

    The surgical anatomy of the nasal tip is determined by intrinsic factors, such as the nasal tip volume, shape, definition, and symmetry. These factors are intimately related to the morphology of the lower lateral cartilages. Tip sutures reduce the need for grafts and allow the surgeon to manipulate the tip with a high degree of precision and better long-term clinical outcomes. In this review, we evaluated common nasal tip suture techniques to clarify the similarities and differences among them. The following nasal tip suture techniques were investigated: medial crural fixation suture, middle crura suture, transdomal (dome creating, dome binding, domal definition) suture, interdomal suture, lateral crural mattress suture, columella septal suture, intercrural suture, tip rotation suture, craniocaudal transdomal suture, lateral crural spanning suture, suspension suture, tongue-in-groove technique, and lateral crural steal. Tip sutures increase tip projection, narrow the tip, provide stabilization, and provide tip rotation. The sutures may be used separately or together. Nasal tip sutures have long been used as noninvasive suture techniques. Each suture technique has unique benefits, and various key points must be considered when using these techniques.

  14. Injector tip for an internal combustion engine

    Science.gov (United States)

    Shyu, Tsu Pin; Ye, Wen

    2003-05-20

    This invention relates to a the tip structure of a fuel injector as used in a internal combustion engine. Internal combustion engines using Homogeneous Charge Compression Ignition (HCCI) technology require a tip structure that directs fuel spray in a downward direction. This requirement necessitates a tip design that is capable of withstanding mechanical stresses associated with the design.

  15. Direct calculation of wind turbine tip loss

    DEFF Research Database (Denmark)

    Wood, D.H.; Okulov, Valery; Bhattacharjee, D.

    2016-01-01

    The usual method to account for a finite number of blades in blade element calculations of wind turbine performance is through a tip loss factor. Most analyses use the tip loss approximation due to Prandtl which is easily and cheaply calculated but is known to be inaccurate at low tip speed ratio...

  16. Pro Photo Tips: For Students

    OpenAIRE

    Scott, Grant

    2014-01-01

    Pro Photo Tips: For Students has been specifically created for students studying photography at school, college or university. \\ud \\ud Each film is presented by photographer and university lecturer Grant Scott who brings his thirty years experience of working with professional photography and photographers to each area of photographic practice he discuss's. Using simple to understand language he gives you the information and inspiration you need to succeed in your studies and create a future ...

  17. Structural Health Monitoring on Turbine Engines Using Microwave Blade Tip Clearance Sensors

    Science.gov (United States)

    Woike, Mark; Abdul-Aziz, Ali; Clem, Michelle

    2014-01-01

    The ability to monitor the structural health of the rotating components, especially in the hot sections of turbine engines, is of major interest to aero community in improving engine safety and reliability. The use of instrumentation for these applications remains very challenging. It requires sensors and techniques that are highly accurate, are able to operate in a high temperature environment, and can detect minute changes and hidden flaws before catastrophic events occur. The National Aeronautics and Space Administration (NASA) has taken a lead role in the investigation of new sensor technologies and techniques for the in situ structural health monitoring of gas turbine engines. As part of this effort, microwave sensor technology has been investigated as a means of making high temperature non-contact blade tip clearance, blade tip timing, and blade vibration measurements for use in gas turbine engines. This paper presents a summary of key results and findings obtained from the evaluation of two different types of microwave sensors that have been investigated for use possible in structural health monitoring applications. The first is a microwave blade tip clearance sensor that has been evaluated on a large scale Axial Vane Fan, a subscale Turbofan, and more recently on sub-scale turbine engine like disks. The second is a novel microwave based blade vibration sensor that was also used in parallel with the microwave blade tip clearance sensors on the experiments with the sub-scale turbine engine disks.

  18. Structural Stability and Vibration

    DEFF Research Database (Denmark)

    Wiggers, Sine Leergaard; Pedersen, Pauli

    This book offers an integrated introduction to the topic of stability and vibration. Strikingly, it describes stability as a function of boundary conditions and eigenfrequency as a function of both boundary conditions and column force. Based on a post graduate course held by the author at the Uni......This book offers an integrated introduction to the topic of stability and vibration. Strikingly, it describes stability as a function of boundary conditions and eigenfrequency as a function of both boundary conditions and column force. Based on a post graduate course held by the author...... and their derivation, thus stimulating them to write interactive and dynamic programs to analyze instability and vibrational modes....

  19. Development of a Millikelvin dual-tip Josephson scanning tunneling microscope

    Science.gov (United States)

    Roychowdhury, Anita

    In this thesis, I first describe the design and construction of a dual-tip millikelvin STM system. The STM is mounted on a dilution refrigerator and the setup includes vibration isolation, rf-filtered wiring, an ultra high vacuum (UHV) sample preparation chamber and sample transfer mechanism. Next I describe a novel superconducting tip fabrication technique. My technique involves dry-etching sections of 250 mum diameter Nb wire with an SF6 plasma in a reactive ion etcher. I present data taken with these tips on various samples at temperatures ranging from 30 mK to 9 K. My results demonstrate that the tips are superconducting, achieve good spectroscopic energy resolution, are mechanically robust over long time periods, and are atomically sharp. I also show data characterizing the performance of our system. This data is in the form of atomic resolution images, spectroscopy, noise spectra and simultaneous scans taken with both tips of the STM. I used these to examine the tip-sample stability, cross talk between the two tips, and to extract the effective noise temperature (˜185 mK) of the sample by fitting the spectroscopy data to a voltage noise model. Finally, I present spectroscopy data taken with a Nb tip on a Nb(100) sample at 30 mK. The enhanced spectroscopic resolution at this temperature allowed me to resolve peaks in the fluctuation-dominated supercurrent at sub-gap voltages. My analysis indicates that these peaks are due to the incoherent tunneling of Cooper pairs at resonant frequencies of the STM's electromagnetic environment. By measuring the response of the STM junction to microwaves, I identified the charge carriers in this regime as Cooper pairs with charge 2e. The amplitude of the response current scales as the square of the Bessel functions, indicating that the pair tunneling originates from photon assisted tunneling in the incoherent regime, rather than the more conventionally observed Shapiro steps in the coherent regime.

  20. Equilibrium structure and atomic vibrations of Nin clusters

    Science.gov (United States)

    Borisova, Svetlana D.; Rusina, Galina G.

    2017-12-01

    The equilibrium bond lengths and binding energy, second differences in energy and vibrational frequencies of free clusters Nin (2 ≤ n ≤ 20) were calculated with the use of the interaction potential obtained in the tight-binding approximation (TBA). The results show that the minimum vibration frequency plays a significant role in the evaluation of the dynamic stability of the clusters. A nonmonotonic dependence of the minimum vibration frequency of clusters on their size and the extreme values for the number of atoms in a cluster n = 4, 6, 13, and 19 are demonstrated. This result agrees with the theoretical and experimental data on stable structures of small metallic clusters.

  1. Vibration Analysis and the Accelerometer

    Science.gov (United States)

    Hammer, Paul

    2011-01-01

    Have you ever put your hand on an electric motor or motor-driven electric appliance and felt it vibrate? Ever wonder why it vibrates? What is there about the operation of the motor, or the object to which it is attached, that causes the vibrations? Is there anything "regular" about the vibrations, or are they the result of random causes? In this…

  2. Comparison of Various Supersonic Turbine Tip Designs to Minimize Aerodynamic Loss and Tip Heating

    Science.gov (United States)

    Shyam, Vikram; Ameri, Ali

    2012-01-01

    The rotor tips of axial turbines experience high heat flux and are the cause of aerodynamic losses due to tip clearance flows, and in the case of supersonic tips, shocks. As stage loadings increase, the flow in the tip gap approaches and exceeds sonic conditions. This introduces effects such as shock-boundary layer interactions and choked flow that are not observed for subsonic tip flows that have been studied extensively in literature. This work simulates the tip clearance flow for a flat tip, a diverging tip gap and several contoured tips to assess the possibility of minimizing tip heat flux while maintaining a constant massflow from the pressure side to the suction side of the rotor, through the tip clearance. The Computational Fluid Dynamics (CFD) code GlennHT was used for the simulations. Due to the strong favorable pressure gradients the simulations assumed laminar conditions in the tip gap. The nominal tip gap width to height ratio for this study is 6.0. The Reynolds number of the flow is 2.4 x 10(exp 5) based on nominal tip width and exit velocity. A wavy wall design was found to reduce heat flux by 5 percent but suffered from an additional 6 percent in aerodynamic loss coefficient. Conventional tip recesses are found to perform far worse than a flat tip due to severe shock heating. Overall, the baseline flat tip was the second best performer. A diverging converging tip gap with a hole was found to be the best choice. Average tip heat flux was reduced by 37 percent and aerodynamic losses were cut by over 6 percent.

  3. Nanomechanical dissipation at a tip-induced Kondo onset

    Science.gov (United States)

    Baruselli, Pier Paolo; Fabrizio, Michele; Tosatti, Erio

    2017-08-01

    The onset or demise of Kondo effect in a magnetic impurity on a metal surface can be triggered, as sometimes observed, by the simple mechanical nudging of a tip. Such a mechanically driven quantum phase transition must reflect in a corresponding mechanical dissipation peak; yet, this kind of signature has not been focused upon so far. Aiming at the simplest theoretical modeling, we treat the impurity as an Anderson impurity model, the tip action as a hybridization switching, and solve the problem by numerical renormalization group. Studying this model as function of temperature and magnetic field we are able to isolate the Kondo contribution to dissipation. While that is, reasonably, of the order of the Kondo energy, its temperature evolution shows a surprisingly large tail even above the Kondo temperature. The detectability of Kondo mechanical dissipation in atomic force microscopy is also discussed.

  4. Tip-enhanced near-field optical microscopy.

    Science.gov (United States)

    Hartschuh, Achim

    2008-01-01

    Spectroscopic methods with high spatial resolution are essential for understanding the physical and chemical properties of nanoscale materials, including quantum structures and biological surfaces. An optical technique is reviewed that relies on the enhanced electric fields in the proximity of a sharp, laser-irradiated metal tip. These fields are utilized for spatially confined probing of various optical signals, thus allowing for a detailed sample characterization far below the diffraction limit. In addition, tip-enhanced fields also provide the sensitivity crucial for the detection of nanoscale volumes. After outlining the principles of near-field optics, the mechanisms contributing to local field enhancement and how it can be used to enhance optical signals are discussed. Different experimental methods are presented and several recent examples of Raman and fluorescence microscopy with 10 nm spatial resolution of single molecules are reviewed.

  5. Vibrations and Stability

    DEFF Research Database (Denmark)

    Thomsen, Jon Juel

    About this textbook An ideal text for students that ties together classical and modern topics of advanced vibration analysis in an interesting and lucid manner. It provides students with a background in elementary vibrations with the tools necessary for understanding and analyzing more complex...... dynamical phenomena that can be encountered in engineering and scientific practice. It progresses steadily from linear vibration theory over various levels of nonlinearity to bifurcation analysis, global dynamics and chaotic vibrations. It trains the student to analyze simple models, recognize nonlinear...... phenomena and work with advanced tools such as perturbation analysis and bifurcation analysis. Explaining theory in terms of relevant examples from real systems, this book is user-friendly and meets the increasing interest in non-linear dynamics in mechanical/structural engineering and applied mathematics...

  6. Experimental – Numerical Analysis of Stress State in Front of the Crack Tip of Modified and Unmodified G17CrMo5-5 Cast Steel by Rare Earth Metals in a Brittle-Ductile Transition Region

    Directory of Open Access Journals (Sweden)

    Dzioba I.

    2016-06-01

    Full Text Available In the paper presented experimental data and numerical analysis of stress distribution in front of the crack of two melts of low-alloy G17CrMo5-5 cast steel-modified (M by rare earth metals and original, unmodified (UM in the temperature range, according to the brittle-ductile transition region. Experimental tests include determination of the tensile properties and fracture toughness characteristics for the UM and M cast steel. Numerical analysis includes determination of stress distribution in front of the crack at the initial moment of the crack extension. In the numerical computations, experimentally tested specimens SEN(B were modeled. The true stress-strain curves for the UM and M cast steel were used in the calculation. It was shown that the maximum of the opening stresses at the initial moment of the crack extension occurs in the axis of the specimens and reaches similar level of about 3.5σ0 for both UM and M cast steel. However, the length of the critical distance, measured for stress level equal 3σ0, is great for the M in comparison to the UM cast steel. Also was shown that the UM cast steel increased the level of the stress state triaxiality parameters that resulted in a decrease of fracture toughness.

  7. Anbar Awakens: The Tipping Point

    Science.gov (United States)

    2008-04-01

    CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ...ORGANIZATION NAME(S) AND ADDRESS(ES) Army Combined Arms Center,Army & Marine CounterInsurgency Center (COIN),Fort Leavenworth,KS,66027 8. PERFORMING ...radical change, or a “tipping point,” to occur: mavens, salespersons , and connectors. in brief, mavens have the goods, salespersons spread the word, and

  8. Nail photography: Tips and tricks

    Directory of Open Access Journals (Sweden)

    Feroze Kaliyadan

    2016-01-01

    Full Text Available Photographic documentation of the nails is important in the objective evaluation of response to treatment and in disseminating scientific information related to nail diseases. The key to a good image of the nail is proper framing and achieving a sharp focused image with good contrast with the background, at the same time avoiding strong reflections from the nail surface. While the general principles of clinical photography apply to nail imaging also, this article attempts to highlight some tips which can be specifically used to improve the quality of nail images.

  9. Nail Photography: Tips and Tricks.

    Science.gov (United States)

    Kaliyadan, Feroze; Ashique, K T

    2016-01-01

    Photographic documentation of the nails is important in the objective evaluation of response to treatment and in disseminating scientific information related to nail diseases. The key to a good image of the nail is proper framing and achieving a sharp focused image with good contrast with the background, at the same time avoiding strong reflections from the nail surface. While the general principles of clinical photography apply to nail imaging also, this article attempts to highlight some tips which can be specifically used to improve the quality of nail images.

  10. Windows 8 visual quick tips

    CERN Document Server

    McFedries, Paul

    2012-01-01

    Easy-in, easy-out format covers all the bells and whistles of Windows 8 If you want to learn how to work smarter and faster in Microsoft's Windows 8 operating system, this easy-to-use, compact guide delivers the goods. Designed for visual learners, it features short explanations and full-color screen shots on almost every page, and it's packed with timesaving tips and helpful productivity tricks. From enhancing performance and managing digital content to setting up security and much more, this handy guide will help you get more out of Windows 8. Uses full-color screen shots and short, step-by-

  11. Quick-Connect Windowed Non-Stick Penetrator Tips for Rapid Sampling

    Science.gov (United States)

    Sherritt, Stewart; Jones, Jack A.; Badescu, Mircea

    2009-01-01

    Standard penetrator sampling systems were designed in order to allow for sampling via penetrators to produce a full set of sample acquisitions including volatile liquids, fine powders, and solid fragments. A gravity harpoon sampler has been designed with a removable tip and a quick coupling. The separation allows for sample handling and eliminates sample cross-contamination. Also, this design allows for multiple use of the penetrator body, which is the largest and heaviest part of the penetrator, while allowing for multiple changes of the light-mass, penetrator tip to avoid sample cross-contamination. The penetrator tip design has been improved by adding a spring trap to retain the sample, as well as a means for connecting to a quick coupling. Quick connect tips have been demonstrated in a sample handling carousel. The penetrator was released and rewound and the tips were released into a circular platter for rotation into instrument stations. The pyro-harpoon sampler was fabricated and tested with a NASA Standard Initiator (NSI) pyrotechnic charge. Initial tests collected cryogenic ice, but removal of the small pyro-harpoon from the ice was difficult. A brass metal sheath was then fitted over the harpoon tip, and removal from the ice was greatly alleviated by leaving the sheath in the ice. Quartz windows in the tips allow direct optical and spectral imaging and gas chromatography-mass spectrometer (GCMS) pyrolysis, and were found to survive impact. All systems were successfully tested by dropping into sand and into cryogenic ice.

  12. Tipping elements in the Earth's climate system.

    Science.gov (United States)

    Lenton, Timothy M; Held, Hermann; Kriegler, Elmar; Hall, Jim W; Lucht, Wolfgang; Rahmstorf, Stefan; Schellnhuber, Hans Joachim

    2008-02-12

    The term "tipping point" commonly refers to a critical threshold at which a tiny perturbation can qualitatively alter the state or development of a system. Here we introduce the term "tipping element" to describe large-scale components of the Earth system that may pass a tipping point. We critically evaluate potential policy-relevant tipping elements in the climate system under anthropogenic forcing, drawing on the pertinent literature and a recent international workshop to compile a short list, and we assess where their tipping points lie. An expert elicitation is used to help rank their sensitivity to global warming and the uncertainty about the underlying physical mechanisms. Then we explain how, in principle, early warning systems could be established to detect the proximity of some tipping points.

  13. A Stability Formula for Plastic-Tipped Bullets Part 1: Motivation and Development of New Formula

    CERN Document Server

    Courtney, Michael W

    2014-01-01

    Part 1 of this paper describes a modification of the original Miller twist rule for computing gyroscopic bullet stability that is better suited to plastic-tipped bullets. The original Miller twist rule assumes a bullet of constant density, but it also works well for conventional copper (or gilding metal) jacketed lead bullets because the density of copper and lead are sufficiently close. However, the original Miller twist rule significantly underestimates the gyroscopic stability of plastic-tipped bullets, because the density of plastic is much lower than the density of copper and lead. Here, a new amended formula is developed for the gyroscopic stability of plastic-tipped bullets by substituting the length of just the metal portion for the total length in the $(1 + L^2)$ term of the original Miller twist rule. Part 2 describes experimental testing of this new formula on three plastic-tipped bullets. The new formula is relatively accurate for plastic-tipped bullets whose metal portion has nearly uniform densi...

  14. A Stability Formula for Plastic-Tipped Bullets Part 2: Experimental Testing

    CERN Document Server

    Courtney, Michael W

    2014-01-01

    Part 1 of this paper describes a modification of the original Miller twist rule for computing gyroscopic bullet stability that is better suited to plastic-tipped bullets. The original Miller twist rule assumes a bullet of constant density, but it also works well for conventional copper (or gilding metal) jacketed lead bullets because the density of copper and lead are sufficiently close. However, the original Miller twist rule significantly underestimates the gyroscopic stability of plastic-tipped bullets, because the density of plastic is much lower than the density of copper and lead. Here, a new amended formula is developed for the gyroscopic stability of plastic-tipped bullets by substituting the length of just the metal portion for the total length in the (1 + L2) term of the original Miller twist rule. Part 2 describes experimental testing of this new formula on three plastic-tipped bullets. The new formula is relatively accurate for plastic-tipped bullets whose metal portion has nearly uniform density,...

  15. J-band Red Giant Branch Tip Magnitudes for the Distance Indicator

    Science.gov (United States)

    Lee, Hyun-chul; Garcia, Cedar; Pena, Ivana

    2017-12-01

    The tip of the red giant branch is one of the widely used distance measurement methods for the relatively nearby galaxies where the bright individual stars are resolved. Most of the earlier works have used the Photometry in the I-band such as HST ACS/WFC F814W or F850LP for the RGB tip method. Here we look into the RGB tip magnitudes in J-band such as HST WFC3/IR F110W and JWST NIRCam/WF F115W for a wide range of age and metallicity. We find that the J-band (HST WFC3/IR F110W and JWST NIRCam/WF F115W) RGB tip magnitudes do not significantly change compared to that of the I-band (HST ACS/WFC F814W, F850LP) for a wide range of metallicity at given age. Moreover, HST WFC3/IR F110W RGB tip magnitudes stay constant within 0.005 magnitudes for stellar populations with old ages (age > 5 Gyr) at given metallicity.

  16. Thermo-mechanical analysis of FG nanobeam with attached tip mass: an exact solution

    Science.gov (United States)

    Ghadiri, Majid; Jafari, Ali

    2016-12-01

    Present disquisition proposes an analytical solution method for exploring the vibration characteristics of a cantilever functionally graded nanobeam with a concentrated mass exposed to thermal loading for the first time. Thermo-mechanical properties of FGM nanobeam are supposed to change through the thickness direction of beam based on the rule of power-law (P-FGM). The small-scale effect is taken into consideration based on nonlocal elasticity theory of Eringen. Linear temperature rise (LTR) through thickness direction is studied. Existence of centralized mass in the free end of nanobeam influences the mechanical and physical properties. Timoshenko beam theory is employed to derive the nonlocal governing equations and boundary conditions of FGM beam attached with a tip mass under temperature field via Hamilton's principle. An exact solution procedure is exploited to achieve the non-dimensional frequency of FG nanobeam exposed to temperature field with a tip mass. A parametric study is led to assess the efficacy of temperature changes, tip mass, small scale, beam thickness, power-law exponent, slenderness and thermal loading on the natural frequencies of FG cantilever nanobeam with a point mass at the free end. It is concluded that these parameters play remarkable roles on the dynamic behavior of FG nanobeam subjected to LTR with a tip mass. The results for simpler states are confirmed with known data in the literature. Presented numerical results can serve as benchmarks for future thermo-mechanical analyses of FG nanobeam with tip mass.

  17. A Microwave Blade Tip Clearance Sensor for Propulsion Health Monitoring

    Science.gov (United States)

    Woike, Mark R.; Abdul-Aziz, Ali; Bencic, Timothy J.

    2010-01-01

    Microwave sensor technology is being investigated by the NASA Glenn Research Center as a means of making non-contact structural health measurements in the hot sections of gas turbine engines. This type of sensor technology is beneficial in that it is accurate, it has the ability to operate at extremely high temperatures, and is unaffected by contaminants that are present in turbine engines. It is specifically being targeted for use in the High Pressure Turbine (HPT) and High Pressure Compressor (HPC) sections to monitor the structural health of the rotating components. It is intended to use blade tip clearance to monitor blade growth and wear and blade tip timing to monitor blade vibration and deflection. The use of microwave sensors for this application is an emerging concept. Techniques on their use and calibration needed to be developed. As a means of better understanding the issues associated with the microwave sensors, a series of experiments have been conducted to evaluate their performance for aero engine applications. This paper presents the results of these experiments.

  18. Addressing Tipping Points for a Precarious Future

    OpenAIRE

    O'Riordan, Timothy; Lenton, Timothy

    2013-01-01

    This book places tipping points in their scientific, economic, governmental, creative, and spiritual contexts. It seeks to offer a comprehensive set of interpretations on the meaning and application of tipping points. Its contribution focuses on the various characterisations and metaphors of tipping points, on the scope for anticipating their onset, the capacity for societal resilience in the face of their impending arrival, and for better ways of communicating and preparing societies, econom...

  19. Is there a magnitude effect in tipping?

    Science.gov (United States)

    Green, Leonard; Myerson, Joel; Schneider, Rachel

    2003-06-01

    The present study examined nearly 1,000 tips recorded for two taxicabs, two hair salons, and two restaurants. In each of the six cases, amount of tip increased linearly as a function of the amount of the bill. Contrary to standard microeconomic theory, there was a magnitude effect in that as the amount of the bill increased, the percent tip tended to decrease. The present results extend the findings of Chapman and Winquist (1998), obtained using hypothetical scenarios, to real-world tipping behavior. Chapman and Winquist argued that a magnitude effect in tipping reflects the shape of the utility function for money. We suggest, however, that the magnitude effect may be the mathematical consequence of replotting the fundamental relationship between tip and bill amounts in terms of percent tip, given that the observed linear relation between tip and bill amounts has a positive intercept. We suggest further that the positive intercept arises because a tip represents a judgment as to what constitutes a fair or equitable wage, and part of what constitutes a fair wage is independent of the amount of the bill, reflecting compensation for simply being there when needed. The present account implies that different explanations may be needed for magnitude effects observed in different domains.

  20. Fluid Surface Damping: A Technique for Vibration Suppression of Beams

    Directory of Open Access Journals (Sweden)

    Hany Ghoneim

    1997-01-01

    Full Text Available A fluid surface damping (FSD technique for vibration suppression of beamlikestructures is proposed. The technique is a modification of the surface layer damping method. Two viscoelastic surface layers containing fluid-filled cavities are attached symmetrically to the opposite surfaces of the beam. The cavities on one side are attached to the corresponding cavities on the other side via connection passages. As the beam vibrates, the fluid is pumped back and forth through the connecting passages. Therefore, in addition to the viscoelastic damping provided by the surface layers, the technique offers viscous damping due to the fluid flow through the passage. A mathematical model for the proposed technique is developed, normalized, and solved in the frequency domain to investigate the effect of various parameters on the vibration suppression of a cantilever beam. The steady-state frequency response for a base white-noise excitation is calculated at the beam's free tip and over a frequency range containing the first five resonant frequencies. The parameters investigated are the flow-through passage viscous resistance, the length and location of the layers, the hydraulic capacitance of the fluid-filled cavities, and inertia of the moving fluid (hydraulic inertance. Results indicate that the proposed technique has promising potential in the field of vibration suppression of beamlike structures. With two FSD elements, all peak vibration amplitudes can be well suppressed over the entire frequency spectrum studied.

  1. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

    Medline Plus

    Full Text Available ... guidance to connect the portal vein to the hepatic vein in the liver. A small metal device ... organs to the liver) to one of the hepatic veins (three veins that carry blood away from ...

  2. The Vibration Ring. Phase 1; [Seedling Fund

    Science.gov (United States)

    Asnani, Vivake M.; Krantz, Timothy L.; Delap, Damon C.; Stringer, David B.

    2014-01-01

    The vibration ring was conceived as a driveline damping device to prevent structure-borne noise in machines. It has the appearance of a metal ring, and can be installed between any two driveline components like an ordinary mechanical spacer. Damping is achieved using a ring-shaped piezoelectric stack that is poled in the axial direction and connected to an electrical shunt circuit. Surrounding the stack is a metal structure, called the compression cage, which squeezes the stack along its poled axis when excited by radial driveline forces. The stack in turn generates electrical energy, which is either dissipated or harvested using the shunt circuit. Removing energy from the system creates a net damping effect. The vibration ring is much stiffer than traditional damping devices, which allows it to be used in a driveline without disrupting normal operation. In phase 1 of this NASA Seedling Fund project, a combination of design and analysis was used to examine the feasibility of this concept. Several designs were evaluated using solid modeling, finite element analysis, and by creating prototype hardware. Then an analytical model representing the coupled electromechanical response was formulated in closed form. The model was exercised parametrically to examine the stiffness and loss factor spectra of the vibration ring, as well as simulate its damping effect in the context of a simplified driveline model. The results of this work showed that this is a viable mechanism for driveline damping, and provided several lessons for continued development.

  3. The Belgian coal tips: geomorphic and pedogenetic research with community service and educational aspects

    Science.gov (United States)

    Nyssen, Jan; Vermeersch, Dominiek; Diependaele, Stijn; van Ranst, Eric; Derycke, Anja; Corexenos, Pavlos; Palmers, Jo; Poesen, Jean

    2010-05-01

    Coal tips are composed of various materials, essentially sterile rock but also waste such as mine wood, scrap metal as well as scoria from surface facilities. Rocks composing Belgian coal tips belong to the Westfalian and Namurian (approx. 320 Ma) and include psammites, schists and coal residues. Currently, these coal tips are increasingly regarded as socio-cultural heritage. Worldwide, several studies have focused on the factors controlling the magnitude of geomorphic processes, such as nature of slope material, vegetation type and cover, the role of self-ignition and combustion, time and slope gradient. In the international literature, research gaps concern particular processes, such as causes and consequences of the widespread tree toppling and root throw, rock fragment movement at the surface, or gully control by check dams. Especially spatially distributed erosion rates by the various processes active on coal tips, neither sediment budgets seem ever to have been established. The same holds for regional (subcontinental) variability in slope processes on coal tips. The many Belgian coal tips that have not been levelled provide a unique opportunity for geomorphological and pedogenetical studies, which have so far demonstrated the existence of: - correlations between the intensity of observed geomorphic processes and a broad range of bio-physical explanatory factors; - strong and reciprocal influences between the vegetation of coal tips and the morphology of the colonised slopes; - absence of strong relations between gully activity and slope angle, resulting from the narrow range of slope gradients on coal tips; - possibilities to locate landslide risk zones through combined use of Digital Elevation Models and thermographic imagery; - presence of neoformed minerals on burning/burned coal tips, which impact the soil forming processes as well as soil quality.

  4. The tip of the iceberg

    DEFF Research Database (Denmark)

    Bjørst, Lill Rastad

    2010-01-01

      Abstract: The tip of the iceberg: Ice as a nonhuman actor of the climate change debate   The global climate change debate has the Arctic as a core region of concern and ice has become a central aspect of discourses. This article discusses ice representations from six different contexts linked...... to the 2009 United Nations Climate Change Conference (COP15) in Copenhagen. The author argues that even though the discussions often seem to be centred on ice alone, the latter gets inscribed in narratives and metaphors which have wider implications for how the Arctic and its Indigenous peoples...... are represented. Ice becomes a nonhuman actor, framing the discussions, acting in specific ways, and linking hybrid networks. Indeed it is used in diverse platforms by scientists, politicians, governments, NGOs, as well as Inuit hunters and fishermen...

  5. Lateral Tip Control Effects in CD-AFM Metrology: The Large Tip Limit.

    Science.gov (United States)

    Dixson, Ronald G; Orji, Ndubuisi G; Goldband, Ryan S

    2016-01-25

    Sidewall sensing in critical dimension atomic force microscopes (CD-AFMs) usually involves continuous lateral dithering of the tip or the use of a control algorithm and fast response piezo actuator to position the tip in a manner that resembles touch-triggering of coordinate measuring machine (CMM) probes. All methods of tip position control, however, induce an effective tip width that may deviate from the actual geometrical tip width. Understanding the influence and dependence of the effective tip width on the dither settings and lateral stiffness of the tip can improve the measurement accuracy and uncertainty estimation for CD-AFM measurements. Since CD-AFM typically uses tips that range from 15 nm to 850 nm in geometrical width, the behavior of effective tip width throughout this range should be understood. The National Institute of Standards and Technology (NIST) has been investigating the dependence of effective tip width on the dither settings and lateral stiffness of the tip, as well as the possibility of material effects due to sample composition. For tip widths of 130 nm and lower, which also have lower lateral stiffness, the response of the effective tip width to lateral dither is greater than for larger tips. However, we have concluded that these effects will not generally result in a residual bias, provided that the tip calibration and sample measurement are performed under the same conditions. To validate that our prior conclusions about the dependence of effective tip width on lateral stiffness are valid for large CD-tips, we recently performed experiments using a very large non-CD tip with an etched plateau of approximately 2 μm width. The effective lateral stiffness of these tips is at least 20 times greater than typical CD-AFM tips, and these results supported our prior conclusions about the expected behavior for larger tips. The bottom-line importance of these latest observations is that we can now reasonably conclude that a dither slope of 3 nm

  6. Evaluation of crack-tip stress fields on microstructural-scale fracture in Al-Al2O3 interpenetrating network composites

    Science.gov (United States)

    Robert J. Moon; Mark Hoffman; Jurgen Rödel; Shigemi Tochino; Giuseppe Pezzotti

    2009-01-01

    The influence of local microstructure on the fracture process at the crack tip in a ceramic–metal composite was assessed by comparing the measured stress at a microstructural level and analogous finite element modelling (FEM). Fluorescence microprobe spectroscopy was used to investigate the influence of near-crack-tip stress fields on the resulting crack propagation at...

  7. Vibrational spectroscopy of resveratrol

    Science.gov (United States)

    Billes, Ferenc; Mohammed-Ziegler, Ildikó; Mikosch, Hans; Tyihák, Ernő

    2007-11-01

    In this article the authors deal with the experimental and theoretical interpretation of the vibrational spectra of trans-resveratrol (3,5,4'-trihydroxy- trans-stilbene) of diverse beneficial biological activity. Infrared and Raman spectra of the compound were recorded; density functional calculations were carried out resulting in the optimized geometry and several properties of the molecule. Based on the calculated force constants, a normal coordinate analysis yielded the character of the vibrational modes and the assignment of the measured spectral bands.

  8. Bumblebee vibration activated foraging

    OpenAIRE

    Su, Dan Kuan-Nien

    2009-01-01

    The ability use vibrational signals to activate nestmate foraging is found in the highly social bees, stingless bees and honey bees, and has been hypothesized to exist in the closely related, primitively eusocial bumble bees. We provide the first strong and direct evidence that this is correct. Inside the nest, bumble bee foragers produce brief bursts of vibration (foraging activation pulses) at 594.5 Hz for 63±26 ms (velocityRMS=0.46±0.02mm/s, forceRMS=0.8±0.2 mN. Production of these vibrati...

  9. Man-Induced Vibrations

    DEFF Research Database (Denmark)

    Jönsson, Jeppe; Hansen, Lars Pilegaard

    1994-01-01

    concerned with spectator-induced vertical vibrations on grandstands. The idea is to use impulse response analysis and base the load description on the load impulse. If the method is feasable, it could be used in connection with the formulation of requirements in building codes. During the last two decades...... work has been done on the measurement of the exact load functions and related reponse analysis. A recent work using a spectral description has been performed by Per-Erik Erikson and includes a good literature survey. Bachmann and Ammann give a good overview of vibrations caused by human activity. Other...

  10. Vibrations and waves

    CERN Document Server

    Kaliski, S

    2013-01-01

    This book gives a comprehensive overview of wave phenomena in different media with interacting mechanical, electromagnetic and other fields. Equations describing wave propagation in linear and non-linear elastic media are followed by equations of rheological models, models with internal rotational degrees of freedom and non-local interactions. Equations for coupled fields: thermal, elastic, electromagnetic, piezoelectric, and magneto-spin with adequate boundary conditions are also included. Together with its companion volume Vibrations and Waves. Part A: Vibrations this work provides a wealth

  11. Crack Tip Flipping under Mode I Tearing: Investigated by X-Ray Tomography

    DEFF Research Database (Denmark)

    Nielsen, Kim Lau; Gundlach, Carsten

    2017-01-01

    The fracture surface morphology that results from mode I tearing of ductile plate metals depends heavily on both the elastic-plastic material properties and the microstructure. Severe tunneling of the advancing crack tip (resulting in cup-cup, or bath-tub like fracture surfaces) can take place...

  12. Damage evolution by using the near-tip fields of a crack in gas turbine liners

    NARCIS (Netherlands)

    Altunlu, A.C.; van der Hoogt, Peter; de Boer, Andries

    2010-01-01

    A residual lifetime prediction study has been performed on a combustion liner metallic material exposed to elevated temperatures by simulating the evolution of plastic work fields at a crack tip under monotonically loading. The strain and stress distribution has been computed by finite element

  13. New theory for Mode I crack-tip dislocation emission

    Science.gov (United States)

    Andric, Predrag; Curtin, W. A.

    2017-09-01

    A material is intrinsically ductile under Mode I loading when the critical stress intensity KIe for dislocation emission is lower than the critical stress intensity KIc for cleavage. KIe is usually evaluated using the approximate Rice theory, which predicts a dependence on the elastic constants and the unstable stacking fault energy γusf for slip along the plane of dislocation emission. Here, atomistic simulations across a wide range of fcc metals show that KIe is systematically larger (10-30%) than predicted. However, the critical (crack tip) shear displacement is up to 40% smaller than predicted. The discrepancy arises because Mode I emission is accompanied by the formation of a surface step that is not considered in the Rice theory. A new theory for Mode I emission is presented based on the ideas that (i) the stress resisting step formation at the crack tip creates "lattice trapping" against dislocation emission such that (ii) emission is due to a mechanical instability at the crack tip. The new theory is formulated using a Peierls-type model, naturally includes the energy to form the step, and reduces to the Rice theory (no trapping) when the step energy is small. The new theory predicts a higher KIe at a smaller critical shear displacement, rationalizing deviations of simulations from the Rice theory. Specific predictions of KIe for the simulated materials, usually requiring use of the measured critical crack tip shear displacement due to complex material non-linearity, show very good agreement with simulations. An analytic model involving only γusf, the surface energy γs, and anisotropic elastic constants is shown to be quite accurate, serves as a replacement for the analytical Rice theory, and is used to understand differences between Rice theory and simulation in recent literature. The new theory highlights the role of surface steps created by dislocation emission in Mode I, which has implications not only for intrinsic ductility but also for crack tip

  14. Summer Safety Tips - Staying Safe Outdoors

    Science.gov (United States)

    ... following these tips from the American Academy of Pediatrics (AAP). Also, see Summer Safety Tips: Sun and Water Safety ​ for more information. Fireworks Safety​​ Fireworks can result in severe burns , blindness, scars, and even death. Fireworks that are ...

  15. The Tipping Point in School Culture

    Science.gov (United States)

    Nelsen, Jeff; Hill, Bob

    2009-01-01

    Once changes or innovations reach the tipping point, they spread throughout an organization and become entrenched as part of the culture, becoming "just the way we do things around here." These authors see the tipping point at play with systemic improvement in two urban school districts with which they have worked. Here, they describe…

  16. News: Tripping over tipping points/elements

    Science.gov (United States)

    The term “tipping point” has been used to identify a critical threshold susceptible to a tiny perturbation that can qualitatively alter the state or development of a system. “Tipping element” has been introduced to describe large-scale components of the Earth system that may pass...

  17. Tips for Good Oral Health during Pregnancy

    Science.gov (United States)

    Tips for Good Oral Health During Pregnancy B elow are tips for taking care of your oral health while you are pregnant. Getting ... Dental Association. http: / / www. ada. org/ 993. aspx. Good Oral Health for Two (handout) produced by the Northeast Center ...

  18. Economics of tipping the climate dominoes

    Science.gov (United States)

    Lemoine, Derek; Traeger, Christian P.

    2016-05-01

    Greenhouse gas emissions can trigger irreversible regime shifts in the climate system, known as tipping points. Multiple tipping points affect each other’s probability of occurrence, potentially causing a `domino effect’. We analyse climate policy in the presence of a potential domino effect. We incorporate three different tipping points occurring at unknown thresholds into an integrated climate-economy model. The optimal emission policy considers all possible thresholds and the resulting interactions between tipping points, economic activity, and policy responses into the indefinite future. We quantify the cost of delaying optimal emission controls in the presence of uncertain tipping points and also the benefit of detecting when individual tipping points have been triggered. We show that the presence of these tipping points nearly doubles today’s optimal carbon tax and reduces peak warming along the optimal path by approximately 1 °C. The presence of these tipping points increases the cost of delaying optimal policy until mid-century by nearly 150%.

  19. Atraumatic suction tip for microsurgery: technical note.

    NARCIS (Netherlands)

    Menovsky, T.; Vries, J. de

    2004-01-01

    During microneurosurgery, frequent suction is essential for a successful operative course. A new self-made disposable suction tip is described which facilitates atraumatic suction, even near vital anatomical structures. The efficacy of this suction tip was confirmed in selected operative procedures.

  20. Tips to Help You Get Active

    Science.gov (United States)

    ... A Guide for Teenagers Talking with Patients about Weight Loss: Tips for Primary Care Providers Tips to Help You Get Active Benefits Starting Physical Activity Keep Moving Clinical Trials Understanding Adult Overweight and Obesity Using the World Around You to Stay Healthy ...

  1. Heterogeneous Dynamics of Coupled Vibrations

    NARCIS (Netherlands)

    Cringus, Dan; Jansen, Thomas I. C.; Pshenichnikov, Maxim S.; Schoenlein, RW; Corkum, P; DeSilvestri, S; Nelson, KA; Riedle, E

    2009-01-01

    Frequency-dependent dynamics of coupled stretch vibrations of a water molecule are revealed by 2D IR correlation spectroscopy. These are caused by non-Gaussian fluctuations of the environment around the individual OH stretch vibrations.

  2. Molecular Mechanics of Tip-Link Cadherins

    Science.gov (United States)

    Sotomayor, Marcos; Weihofen, Wilhelm A.; Gaudet, Rachelle; Corey, David P.

    2011-11-01

    The hair-cell tip link, a fine filament directly conveying force to mechanosensitive transduction channels, is likely composed of two proteins, protocadherin-15 and cadherin-23, whose mutation causes deafness. However, their complete molecular structure, elasticity, and deafness-related structural defects remain largely unknown. We present crystal structures of extracellular (EC) tip-link cadherin repeats involved in hereditary deafness and tip link formation. In addition, we show that the deafness mutation D101G, in the linker region between the repeats EC1 and EC2 of cadherin-23, causes a slight bend between repeats and decreases Ca2+ affinity. Molecular dynamics simulations suggest that tip-link cadherin repeats are stiff and that either removing Ca2+ or mutating Ca2+-binding residues reduces rigidity and unfolding strength. The structures and simulations also suggest mechanisms underlying inherited deafness and how cadherin-23 may bind with protocadherin-15 to form the tip link.

  3. Mitigation of tip vortex cavitation by means of air injection on a Kaplan turbine scale model

    Science.gov (United States)

    Rivetti, A.; Angulo, M.; Lucino, C.; Liscia, S.

    2014-03-01

    Kaplan turbines operating at full-load conditions may undergo excessive vibration, noise and cavitation. In such cases, damage by erosion associated to tip vortex cavitation can be observed at the discharge ring. This phenomenon involves design features such as (1) overhang of guide vanes; (2) blade profile; (3) gap increasing size with blade opening; (4) suction head; (5) operation point; and (6) discharge ring stiffness, among others. Tip vortex cavitation may cause erosion at the discharge ring and draft tube inlet following a wavy pattern, in which the number of vanes can be clearly identified. Injection of pressurized air above the runner blade centerline was tested as a mean to mitigate discharge ring cavitation damage on a scale model. Air entrance was observed by means of a high-speed camera in order to track the air trajectory toward its mergence with the tip vortex cavitation core. Post-processing of acceleration signals shows that the level of vibration and the RSI frequency amplitude decrease proportionally with air flow rate injected. These findings reveal the potential mitigating effect of air injection in preventing cavitation damage and will be useful in further tests to be performed on prototype, aiming at determining the optimum air flow rate, size and distribution of the injectors.

  4. Composite Struts Would Damp Vibrations

    Science.gov (United States)

    Dolgin, Benjamin P.

    1991-01-01

    New design of composite-material (fiber/matrix laminate) struts increases damping of longitudinal vibrations without decreasing longitudinal stiffness or increasing weight significantly. Plies with opposing chevron patterns of fibers convert longitudinal vibrational stresses into shear stresses in intermediate viscoelastic layer, which dissipate vibrational energy. Composite strut stronger than aluminum strut of same weight and stiffness.

  5. Ship Vibration Design Guide

    Science.gov (United States)

    1989-07-01

    Frachtschiffen," Werft Reederie Hafen, 1925. 4-21 Noonan, E. F. "Vibration Considerations for 120,000 CM LNG Ships," NKF: Preliminary Report No. 7107, 25...Ship Response to Ice - A Second Season by C. Daley, J. W. St. John, R. Brown, J. Meyer , and I. Glen 1990 SSC-340 Ice Forces and Ship Response to Ice

  6. Compact Vibration Damper

    Science.gov (United States)

    Ivanco, Thomas G. (Inventor)

    2014-01-01

    A vibration damper includes a rigid base with a mass coupled thereto for linear movement thereon. Springs coupled to the mass compress in response to the linear movement along either of two opposing directions. A converter coupled to the mass converts the linear movement to a corresponding rotational movement. A rotary damper coupled to the converter damps the rotational movement.

  7. Vibrations and Eigenvalues

    Indian Academy of Sciences (India)

    The vibrating string problem is the source of much mathematicsand physics. This article describes Lagrange's formulationof a discretised version of the problem and its solution.This is also the first instance of an eigenvalue problem. Author Affiliations. Rajendra Bhatia1. Ashoka University, Rai, Haryana 131 029, India.

  8. Vibration Sensitive Keystroke Analysis

    NARCIS (Netherlands)

    Lopatka, M.; Peetz, M.-H.; van Erp, M.; Stehouwer, H.; van Zaanen, M.

    2009-01-01

    We present a novel method for performing non-invasive biometric analysis on habitual keystroke patterns using a vibration-based feature space. With the increasing availability of 3-D accelerometer chips in laptop computers, conventional methods using time vectors may be augmented using a distinct

  9. Homotopy analysis approach for nonlinear piezoelectric vibration energy harvesting

    Directory of Open Access Journals (Sweden)

    Shahlaei-Far Shahram

    2016-01-01

    Full Text Available Piezoelectric energy harvesting from a vertical geometrically nonlinear cantilever beam with a tip mass subject to transverse harmonic base excitations is analyzed. One piezoelectric patch is placed on the slender beam to convert the tension and compression into electrical voltage. Applying the homotopy analysis method to the coupled electromechanical governing equations, we derive analytical solutions for the horizontal displacement of the tip mass and consequently the output voltage from the piezoelectric patch. Analytical approximation for the frequency response and phase of the geometrically forced nonlinear vibration system are also obtained. The research aims at a rigorous analytical perspective on a nonlinear problem which has previously been solely investigated by numerical and experimental methods.

  10. Visualized Multiprobe Electrical Impedance Measurements with STM Tips Using Shear Force Feedback Control

    Directory of Open Access Journals (Sweden)

    Luis Botaya

    2016-05-01

    Full Text Available Here we devise a multiprobe electrical measurement system based on quartz tuning forks (QTFs and metallic tips capable of having full 3D control over the position of the probes. The system is based on the use of bent tungsten tips that are placed in mechanical contact (glue-free solution with a QTF sensor. Shear forces acting in the probe are measured to control the tip-sample distance in the Z direction. Moreover, the tilting of the tip allows the visualization of the experiment under the optical microscope, allowing the coordination of the probes in X and Y directions. Meanwhile, the metallic tips are connected to a current–voltage amplifier circuit to measure the currents and thus the impedance of the studied samples. We discuss here the different aspects that must be addressed when conducting these multiprobe experiments, such as the amplitude of oscillation, shear force distance control, and wire tilting. Different results obtained in the measurement of calibration samples and microparticles are presented. They demonstrate the feasibility of the system to measure the impedance of the samples with a full 3D control on the position of the nanotips.

  11. Numerical investigation of three wind turbine blade tips

    DEFF Research Database (Denmark)

    Johansen, J.; Sørensen, Niels N.

    2002-01-01

    of attack is presented and further analysis is performed on lift and drag coefficients. It is shown that the original Standard tip results in a more concentrated tip vortex leading to a steeper gradient on bothtangential and normal forces when approaching the tip, whereas the two tapered tips show a more....... The Taper tip keeps the higher loading causing the flapwise bending moment to be higher as seen inmeasurements. To determine the radial variation of lift and drag coefficients the local inflow angle of attack is determined. It is shown that the Standard tip experiences a slightly larger angle of attack...... at the tip compared to the two tapered tips. Thelift coefficients are kept at a more constant level for the two tapered tips due to the decrease in chord, while the drag coefficients actually decrease for the two tapered tips, especially for the Swept tip. For the Swept tip at 12 m/s both lift...

  12. Healthy Eating for Vegetarians: 10 Tips for Vegetarians

    Science.gov (United States)

    ... Guidelines Communicator’s Guide 10 Tips: Healthy Eating for Vegetarians You are here Home 10 Tips: Healthy Eating ... Vegetarians Print Share 10 Tips: Healthy Eating for Vegetarians A vegetarian eating pattern can be a healthy ...

  13. Sensitive Detection of Small Particles in Fluids Using Optical Fiber Tip with Dielectrophoresis

    Directory of Open Access Journals (Sweden)

    Yi-Hsin Tai

    2016-02-01

    Full Text Available This work presents using a tapered fiber tip coated with thin metallic film to detect small particles in water with high sensitivity. When an AC voltage applied to the Ti/Al coated fiber tip and indium tin oxide (ITO substrate, a gradient electric field at the fiber tip induced attractive/repulsive force to suspended small particles due to the frequency-dependent dielectrophoresis (DEP effect. Such DEP force greatly enhanced the concentration of the small particles near the tip. The increase of the local concentration also increased the scattering of surface plasmon wave near the fiber tip. Combined both DEP effect and scattering optical near-field, we show the detection limit of the concentration for 1.36 μm polystyrene beads can be down to 1 particle/mL. The detection limit of the Escherichia coli (E. coli bacteria was 20 CFU/mL. The fiber tip sensor takes advantages of ultrasmall volume, label-free and simple detection system.

  14. Plasmonic near-field probes: a comparison of the campanile geometry with other sharp tips.

    Science.gov (United States)

    Bao, Wei; Staffaroni, Matteo; Bokor, Jeffrey; Salmeron, Miquel B; Yablonovitch, Eli; Cabrini, Stefano; Weber-Bargioni, Alexander; Schuck, P James

    2013-04-08

    Efficient conversion of photonic to plasmonic energy is important for nano-optical applications, particularly imaging and spectroscopy. Recently a new generation of photonic/plasmonic transducers, the 'campanile' probes, has been developed that overcomes many shortcomings of previous near-field probes by efficiently merging broadband field enhancement with bidirectional coupling of far- to near-field electromagnetic modes. In this work we compare the properties of the campanile structure with those of current NSOM tips using finite element simulations. Field confinement, enhancement, and polarization near the apex of the probe are evaluated relative to local fields created by conical tapered tips in vacuum and in tip-substrate gap mode. We show that the campanile design has similar field enhancement and bandwidth capabilities as those of ultra-sharp metallized tips, but without the substrate and sample restrictions inherent in the tip-surface gap mode operation often required by those tips. In addition, we show for the first time that this campanile probe structure also significantly enhances the radiative rate of any dipole emitter located near the probe apex, quantifying the enhanced decay rate and demonstrating that over 90% of the light radiated by the emitter is "captured" by this probe. This is equivalent to collecting the light from a solid angle of ~3.6 pi. These advantages are crucial for performing techniques such as Raman and IR spectroscopy, white-light nano-ellipsometry and ultrafast pump-probe studies at the nanoscale.

  15. A Class of Methods for the Analysis of Blade Tip Timing Data from Bladed Assemblies Undergoing Simultaneous Resonances—Part I: Theoretical Development

    Directory of Open Access Journals (Sweden)

    J. Gallego-Garrido

    2007-01-01

    Full Text Available Blade tip timing is a technique for the measurement of vibrations in rotating bladed assemblies. Although the fundamentals of the technique are simple, the analysis of data obtained in the presence of simultaneously occurring synchronous resonances is problematic. A class of autoregressive-based methods for the analysis of blade tip timing data from assemblies undergoing two simultaneous resonances has been developed. It includes approaches that assume both sinusoidal and general blade tip responses. The methods can handle both synchronous and asynchronous resonances. An exhaustive evaluation of the approaches was performed on simulated data in order to determine their accuracy and sensitivity. One of the techniques was found to perform best on asynchronous resonances and one on synchronous resonances. Both methods yielded very accurate vibration frequency estimates under all conditions of interest.

  16. Compressor Stability Enhancement Using Discrete Tip Injection

    Science.gov (United States)

    Suder, Kenneth L.; Hathaway, Michael D.; Thorp, Scott A.; Strazisar, Anthony J.; Bright, Michelle B.

    2001-01-01

    Mass injection upstream of the tip of a high-speed axial compressor rotor is a stability enhancement approach known to be effective in suppressing small in tip-critical rotors. This process is examined in a transonic axial compressor rotor through experiments and time-averaged Navier-Stokes CFD simulations. Measurements and simulations for discrete injection are presented for a range of injection rates and distributions of injectors around the annulus. The simulations indicate that tip injection increases stability by unloading the rotor tip and that increasing injection velocity improves the effectiveness of tip injection. For the tested rotor, experimental results demonstrate that at 70 percent speed the stalling flow coefficient can be reduced by 30 percent using an injected mass- flow equivalent to 1 percent of the annulus flow. At design speed, the stalling flow coefficient was reduced by 6 percent using an injected mass-fiow equivalent to 2 percent of the annulus flow. The experiments show that stability enhancement is related to the mass-averaged axial velocity at the tip. For a given injected mass-flow, the mass-averaged axial velocity at the tip is increased by injecting flow over discrete portions of the circumference as opposed to full-annular injection. The implications of these results on the design of recirculating casing treatments and other methods to enhance stability will be discussed.

  17. [Suture tip plasty using an endonasal approach].

    Science.gov (United States)

    Tasman, A-J; Palma, P

    2010-09-01

    Over the last two decades, the use of the external approach for primary and secondary rhinoplasties has become increasingly popular. This article illustrates the versatility of endonasal techniques for the correction of nasal tip deformities on the basis of four cases. The approach to the nasal tip and the chosen technique as used in 100 consecutive rhinoplasties were reviewed. For primary and revision tip plasty, endonasal approaches were used in 81% of cases. Preferred incisions were the infracartilaginous approach and the transfixion incision. Using these approaches, correction of the tip was achieved by using sutures to reposition and reshape the alar cartilages and the columella without grafts to the nasal tip in most cases. Nasal tip plasty via endonasal approaches using sutures is technically more challenging compared to the external approach with its superior exposure. This drawback is outweighed by less operating time and faster patient recovery. Contrary to the general trend, the authors believe that endonasal tip plasty techniques using sutures can obviate the external approach and grafts in many cases and should form an integral part of the rhino-surgeon's repertoire.

  18. Combined frequency modulated atomic force microscopy and scanning tunneling microscopy detection for multi-tip scanning probe microscopy applications

    Science.gov (United States)

    Morawski, Ireneusz; Spiegelberg, Richard; Korte, Stefan; Voigtländer, Bert

    2015-12-01

    A method which allows scanning tunneling microscopy (STM) tip biasing independent of the sample bias during frequency modulated atomic force microscopy (AFM) operation is presented. The AFM sensor is supplied by an electronic circuit combining both a frequency shift signal and a tunneling current signal by means of an inductive coupling. This solution enables a control of the tip potential independent of the sample potential. Individual tip biasing is specifically important in order to implement multi-tip STM/AFM applications. An extensional quartz sensor (needle sensor) with a conductive tip is applied to record simultaneously topography and conductivity of the sample. The high resonance frequency of the needle sensor (1 MHz) allows scanning of a large area of the surface being investigated in a reasonably short time. A recipe for the amplitude calibration which is based only on the frequency shift signal and does not require the tip being in contact is presented. Additionally, we show spectral measurements of the mechanical vibration noise of the scanning system used in the investigations.

  19. Damping element for reducing the vibration of an airfoil

    Science.gov (United States)

    Campbell, Christian X; Marra, John J

    2013-11-12

    An airfoil (10) is provided with a tip (12) having an opening (14) to a center channel (24). A damping element (16) is inserted within the opening of the center channel, to reduce an induced vibration of the airfoil. The mass of the damping element, a spring constant of the damping element within the center channel, and/or a mounting location (58) of the damping element within the center channel may be adjustably varied, to shift a resonance frequency of the airfoil outside a natural operating frequency of the airfoil.

  20. Model reduction and analysis of a vibrating beam microgyroscope

    KAUST Repository

    Ghommem, Mehdi

    2012-05-08

    The present work is concerned with the nonlinear dynamic analysis of a vibrating beam microgyroscope composed of a rotating cantilever beam with a tip mass at its end. The rigid mass is coupled to two orthogonal electrodes in the drive and sense directions, which are attached to the rotating base. The microbeam is driven by an AC voltage in the drive direction, which induces vibrations in the orthogonal sense direction due to rotation about the microbeam axis. The electrode placed in the sense direction is used to measure the induced motions and extract the underlying angular speed. A reduced-order model of the gyroscope is developed using the method of multiple scales and used to examine its dynamic behavior. © The Author(s) 2012 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  1. Animal Communications Through Seismic Vibrations

    Energy Technology Data Exchange (ETDEWEB)

    Hill, Peggy (University of Tulsa)

    2001-05-02

    Substrate vibration has been important to animals as a channel of communication for millions of years, but our literature on vibration in this context of biologically relevant information is only decades old. The jaw mechanism of the earliest land vertebrates allowed them to perceive substrate vibrations as their heads lay on the ground long before airborne sounds could be heard. Although the exact mechanism of vibration production and the precise nature of the wave produced are not always understood, recent development of affordable instrumentation to detect and measure vibrations has allowed researchers to answer increasingly sophisticated questions about how animals send and receive vibration signals. We now know that vibration provides information used in predator defense, prey detection, recruitment to food, mate choice, intrasexual competition, and maternal/brood social interactions in a variety of insect orders, spiders, crabs, scorpions, chameleons, frogs, golden moles, mole rats, kangaroos rats, wallabies, elephants and bison.

  2. CFD analysis of cloud cavitation on three tip-modified propellers with systematically varied tip geometry

    Science.gov (United States)

    Shin, K. W.; Andersen, P.

    2015-12-01

    The blade tip loading is often reduced as an effort to restrain sheet and tip vortex cavitation in the design of marine propellers. This CFD analysis demonstrates that an excessive reduction of the tip loading can cause cloud cavitation responsible for much of noise and surface erosion. Detached eddy simulations (DES) are made for cavitating flows on three tip- modified propellers, of which one is a reference propeller having an experimental result from a cavitation tunnel test with a hull model, and the other two are modified from the reference propeller by altering the blade tip loading. DES results have been validated against the experiment in terms of sheet and cloud cavitation. In DES, non-uniform hull wake is modelled by using the inlet flow and momentum sources instead of including a hull model. A 4-bladed Kappel propeller with a smooth tip bending towards the suction side is used as the reference propeller. For the reference propeller, sheet cavitation extends over a whole chord length in the hull wake peak. As the blade gets out of the wake peak, the rear part of sheet cavity is detached in a form of cloud cavitation. For the reference propeller, the tip pitch reduction from the maximum is about 35%. When decreasing the tip pitch reduction to 10%, tip vortex cavitation is formed and cloud cavitation is significantly weakened. When increasing the tip pitch reduction to 60%, sheet cavitation slightly moves to inner radii and cloud cavitation grows larger.

  3. Vibration Attenuation of Plate Using Multiple Vibration Absorbers

    Directory of Open Access Journals (Sweden)

    Zaman Izzuddin

    2014-07-01

    Full Text Available Vibrations are undesired phenomenon and it can cause harm, distress and unsettling influence to the systems or structures, for example, aircraft, automobile, machinery and building. One of the approach to limit this vibration by introducing passive vibration absorber attached to the structure. In this paper, the adequacy of utilizing passive vibration absorbers are investigated. The vibration absorber system is designed to minimize the vibration of a thin plate fixed along edges. The plate’s vibration characteristics, such as, natural frequency and mode shape are determined using three techniques: theoretical equations, finite element (FE analysis and experiment. The results demonstrate that the first four natural frequencies of fixed-fixed ends plate are 48, 121, 193 and 242 Hz, and these results are corroborated well with theoretical, FE simulation and experiment. The experiment work is further carried out with attached single and multiple vibration absorbers onto plate by tuning the absorber’s frequency to match with the excitation frequency. The outcomes depict that multiple vibration absorbers are more viable in lessening the global structural vibration.

  4. Index assignment of a carbon nanotube rope using tip-enhanced Raman spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Goss, Karin; Schneider, Claus M.; Meyer, Carola [Peter Gruenberg Institut, Forschungszentrum Juelich and JARA Juelich Aachen Research Alliance, 52425 Juelich (Germany); Peica, Niculina; Thomsen, Christian; Maultzsch, Janina [Institut fuer Festkoerperphysik, Technische Universitaet Berlin, Hardenberg Str. 36, 10623 Berlin (Germany)

    2011-11-15

    We used tip-enhanced Raman spectroscopy to study the diameter-dependent Raman modes in a contacted carbon nanotube (CNT) rope. We show that with the near-field tip enhancement a large number of nanotubes within a rope can be identified, even if the nanotube modes cannot be distinguished in the far-field signal. Several metallic and semiconducting nanotubes can be identified and assigned to nanotube families. Additionally, we provide a tentative chiral index assignment. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  5. Focal muscle vibration: evaluation of physical properties and his applications

    Directory of Open Access Journals (Sweden)

    Filippo Camerota

    2014-03-01

    Full Text Available Vibration is the sensation produced by sinusoidal oscillation of objects placed against the skin. The vibratory frequency is signaled bythe frequency of action potentials fired by the sensory nerves and the total number of active sensory nerves is linearly related to theamplitude of vibration. In the last years many works were done evaluating the different clinical applications of the focal musclevibration; the aim of this work is to analyze the interaction between the vibratory application and the skin. For this study theapparatus of focal muscle vibration analyzed was firstly calibrated by measuring the actual peak to peak displacement of the tip as afunction of the power supplied to the shaker; then were measured the Direct Component (DC of the force by which the shaker ispushed against the patient’s skin and the Alternate Component (AC. We observed that from displacements imposed by the tipranging from 0 to about 200 micrometers, the applied load increases monotonically, but non linearly, with the displacement; abovethis value, any further increase of the peak to peak displacements actually does not lead to an effective increase of the amplitude of themechanical stimulation. We can conclude that with this focal muscle vibration applied to the muscle we are able to stimulate thespindles that respond to 200 micrometers amplitude that are probably ones able to generate a proprioceptive signal.

  6. A 30 mK, 13.5 T scanning tunneling microscope with two independent tips

    Science.gov (United States)

    Roychowdhury, Anita; Gubrud, M. A.; Dana, R.; Anderson, J. R.; Lobb, C. J.; Wellstood, F. C.; Dreyer, M.

    2014-04-01

    We describe the design, construction, and performance of an ultra-low temperature, high-field scanning tunneling microscope (STM) with two independent tips. The STM is mounted on a dilution refrigerator and operates at a base temperature of 30 mK with magnetic fields of up to 13.5 T. We focus on the design of the two-tip STM head, as well as the sample transfer mechanism, which allows in situ transfer from an ultra high vacuum preparation chamber while the STM is at 1.5 K. Other design details such as the vibration isolation and rf-filtered wiring are also described. Their effectiveness is demonstrated via spectral current noise characteristics and the root mean square roughness of atomic resolution images. The high-field capability is shown by the magnetic field dependence of the superconducting gap of CuxBi2Se3. Finally, we present images and spectroscopy taken with superconducting Nb tips with the refrigerator at 35 mK that indicate that the effective temperature of our tips/sample is approximately 184 mK, corresponding to an energy resolution of 16 μeV.

  7. Tip trajectories of a smart micro-cantilever beam: analysis and design

    Science.gov (United States)

    Chen, Y.; Dick, A. J.; Ghorbel, F. H.

    2009-11-01

    The tip trajectories of a smart micro-cantilever beam consisting of an atomic force microscope probe with an additional segment of piezoelectric material on top of the probe are studied. A precise model with inhomogeneous partial differential equations and compatible inhomogeneous boundary conditions is developed to describe the dynamics of the smart micro-cantilever beam. The forced vibration solution of this model with respect to two independent inputs from the piezoelectric actuator and the base excitation is derived. By using this solution and the geometric relationship, the trajectory of the end of the tip is obtained from the motion of the free end of the cantilever beam. On the basis of the resonant response to harmonic inputs at the second dynamic mode, nano-scale elliptical and linear tip trajectories are predicted. Within this paper, a smart micro-cantilever beam is shown to produce nano-scale curved tip trajectories for the first time. Analytical and simulation findings indicate that the characteristics of the resulting trajectories are influenced by the magnitudes of two inputs. Potential applications of the elliptical and linear trajectories for nanomanipulation are proposed.

  8. Tracking Blade Tip Vortices for Numerical Flow Simulations of Hovering Rotorcraft

    Science.gov (United States)

    Kao, David L.

    2016-01-01

    Blade tip vortices generated by a helicopter rotor blade are a major source of rotor noise and airframe vibration. This occurs when a vortex passes closely by, and interacts with, a rotor blade. The accurate prediction of Blade Vortex Interaction (BVI) continues to be a challenge for Computational Fluid Dynamics (CFD). Though considerable research has been devoted to BVI noise reduction and experimental techniques for measuring the blade tip vortices in a wind tunnel, there are only a handful of post-processing tools available for extracting vortex core lines from CFD simulation data. In order to calculate the vortex core radius, most of these tools require the user to manually select a vortex core to perform the calculation. Furthermore, none of them provide the capability to track the growth of a vortex core, which is a measure of how quickly the vortex diffuses over time. This paper introduces an automated approach for tracking the core growth of a blade tip vortex from CFD simulations of rotorcraft in hover. The proposed approach offers an effective method for the quantification and visualization of blade tip vortices in helicopter rotor wakes. Keywords: vortex core, feature extraction, CFD, numerical flow visualization

  9. Anodic Dissolution Behavior of the Crack Tip of X70 Pipeline Steel in Near-Neutral pH Environment

    Science.gov (United States)

    Cui, Zhongyu; Wang, Liwei; Liu, Zhiyong; Du, Cuiwei; Li, Xiaogang; Wang, Xin

    2016-12-01

    In this work, the anodic dissolution behavior of the fresh metal surface at crack tip of X70 steel in near-neutral pH environment was investigated using galvanic corrosion simulation method. The solution environment, strain, strain rate, hydrogen enrichment, and fresh metal surface at the crack tip were considered. Corrosion current of the specimen during fast stretching increased linearly with plastic strain. The increment and increase rate of the corrosion current during plastic deformation stage were dependent on the strain rate. Combining Faraday's law and crack tip strain rate equation, the crack growth rate (CGR) induced by the anodic dissolution of the fresh metal surface was calculated. Results show that CGR caused by anodic dissolution was roughly one order lower than that measured on the compact tensile specimen under cyclic load. This finding indicated that hydrogen embrittlement may play a dominate role in stress corrosion crack propagation of pipeline steels in near-neutral pH environment.

  10. Good vibrations. [Hydraulic turbines

    Energy Technology Data Exchange (ETDEWEB)

    Reynolds, P.

    1994-07-01

    The latest developments in the Voith Turbine Control and Automation System (VTLS), which couples digital control technology to hydropower plant equipment, are described. Prominent among these is the vibration diagnostics module for hydraulic turbines. It provides machine-specific diagnostic logic for a vibration monitoring and analysis system. Of the two other VTLS modules described, the operation module optimizes the control of a power plant with three or more turbines by considering the individual properties of each in turn, recommending which should be run, and how, in order to partition the load for a required power output. The cavitation module is a diagnostic system which enables the limits of operation of the turbines to be extended to bands just outside those determined by cavitation calculations. (3 figures). (UK)

  11. Why pay extra? Tipping and the importance of social norms and feelings in economic theory

    OpenAIRE

    Azar, Ofer H.

    2005-01-01

    Tipping is a multi-billion-dollar phenomenon that standard economic models find hard to explain. I discuss several aspects of tipping and divide tipping to six different categories: reward-tipping, price- tipping, tipping-in-advance, bribery-tipping, holiday-tipping and gift- tipping, and discuss the economics of each category. Often tipping has economic justification, because it solves some inefficiency and increases welfare. Analyzing the potential reasons for tipping illustrates the import...

  12. Clean Firetube Boiler Waterside Heat Transfer Surfaces, Energy Tips: STEAM, Steam Tip Sheet #7 (Fact Sheet)

    Energy Technology Data Exchange (ETDEWEB)

    2012-04-01

    A steam energy tip sheet for the Advanced Manufacturing Office (AMO). The prevention of scale formation in firetube boilers can result in substantial energy savings. Scale deposits occur when calcium, magnesium, and silica, commonly found in most water supplies, react to form a continuous layer of material on the waterside of the boiler heat exchange tubes. Scale creates a problem because it typically possesses a thermal conductivity, an order of magnitude less than the corresponding value for bare steel. Even thin layers of scale serve as an effective insulator and retard heat transfer. The result is overheating of boiler tube metal, tube failures, and loss of energy efficiency. Fuel consumption may increase by up to 5% in firetube boilers because of scale. The boilers steam production may be reduced if the firing rate cannot be increased to compensate for the decrease in combustion efficiency. Energy losses as a function of scale thickness and composition are given. Any scale in a boiler is undesirable. The best way to deal with scale is not to let it form in the first place. Prevent scale formation by: (1) Pretreating of boiler makeup water (using water softeners, demineralizers, and reverse osmosis to remove scale-forming minerals); (2) Injecting chemicals into the boiler feedwater; and (3) Adopting proper boiler blowdown practices.

  13. Pickin’ up good vibrations

    CERN Multimedia

    Katarina Anthony

    2015-01-01

    In preparation for the civil engineering work on the HL-LHC, vibration measurements were carried out at the LHC’s Point 1 last month. These measurements will help evaluate how civil engineering work could impact the beam, and will provide crucial details about the site’s geological make-up before construction begins.   A seismic truck at Point 1 generated wave-like vibrations measured by EN/MME. From carrying out R&D to produce state-of-the-art magnets to developing innovative, robust materials capable of withstanding beam impact, the HL-LHC is a multi-faceted project involving many groups and teams across CERN’s departments. It was in this framework that the project management mandated CERN's Mechanical and Materials Engineering (EN/MME) group to measure the propagation of vibrations around Point 1. Their question: can civil engineering work for the HL-LHC – the bulk of which is scheduled for LS2 – begin while the LHC is running? Alth...

  14. Vibrational stability of graphene

    Directory of Open Access Journals (Sweden)

    Yangfan Hu

    2013-05-01

    Full Text Available The mechanical stability of graphene as temperature rises is analyzed based on three different self-consistent phonon (SCP models. Compared with three-dimensional (3-D materials, the critical temperature Ti at which instability occurs for graphene is much closer to its melting temperature Tm obtained from Monte Carlo simulation (Ti ≃ 2Tm, K. V. Zakharchenko, A. Fasolino, J. H. Los, and M. I. Katsnelson, J. Phys. Condens. Matter 23, 202202. This suggests that thermal vibration plays a significant role in melting of graphene while melting for 3-D materials is often dominated by topologic defects. This peculiar property of graphene derives from its high structural anisotropy, which is characterized by the vibrational anisotropic coefficient (VAC, defined upon its Lindermann ratios in different directions. For any carbon based material with a graphene-like structure, the VAC value must be smaller than 5.4 to maintain its stability. It is also found that the high VAC value of graphene is responsible for its negative thermal expansion coefficient at low temperature range. We believe that the VAC can be regarded as a new criterion concerning the vibrational stability of any low-dimensional (low-D materials.

  15. Impetigo: Tips for Treatment and Prevention

    Science.gov (United States)

    ... DO Videos Contact Close ‹ Back to Healthy Living Impetigo: Tips for Treatment and Prevention The symptoms of ... to other parts of their bodies. Causes of Impetigo Impetigo usually affects preschool and school-aged children, ...

  16. Get Moving: Easy Tips to Get Active!

    Science.gov (United States)

    ... Preschoolers Infographic How to Make a Healthy Home Dietary Recommendations for Healthy Children Top 10 Tips to Help Children Develop Healthy Habits Fruit and Veggie Toolkit for Kids Healthy Foods ...

  17. Compressor airfoil tip clearance optimization system

    Science.gov (United States)

    Little, David A.; Pu, Zhengxiang

    2015-08-18

    A compressor airfoil tip clearance optimization system for reducing a gap between a tip of a compressor airfoil and a radially adjacent component of a turbine engine is disclosed. The turbine engine may include ID and OD flowpath boundaries configured to minimize compressor airfoil tip clearances during turbine engine operation in cooperation with one or more clearance reduction systems that are configured to move the rotor assembly axially to reduce tip clearance. The configurations of the ID and OD flowpath boundaries enhance the effectiveness of the axial movement of the rotor assembly, which includes movement of the ID flowpath boundary. During operation of the turbine engine, the rotor assembly may be moved axially to increase the efficiency of the turbine engine.

  18. Time and project management tips for educators.

    Science.gov (United States)

    Shellenbarger, Teresa

    2009-07-01

    As work demands increase, educators need to manage time and work projects effectively. This column provides guidelines and tips that continuing education and staff development professionals in all settings can use to take control of time and work projects.

  19. Time for Some Summer Sun Safety Tips

    Science.gov (United States)

    ... page: https://medlineplus.gov/news/fullstory_166721.html Time for Some Summer Sun Safety Tips Pediatricians offer ... isn't there. Summertime often means more unsupervised time Be aware that changes in your routine might ...

  20. Back-to-School Health Tips: Immunizations

    Science.gov (United States)

    ... JavaScript on. Feature: Back-to-School Health Tips: Immunizations Past Issues / Fall 2014 Table of Contents Your ... eating healthy lunches and snacks. Check-Ups and Immunizations It's a good idea to take your child ...

  1. Impetigo: Tips for Treatment and Prevention

    Science.gov (United States)

    ... to Healthy Living Impetigo: Tips for Treatment and Prevention The symptoms of impetigo are honey-colored, crusty ... or anything that person has touched. Treatment and Prevention Even though impetigo is not dangerous, complications can ...

  2. Tips to Manage Anxiety and Stress

    Science.gov (United States)

    ... Contact ADAA Public Tips to Manage Anxiety and Stress When you're feeling anxious or stressed, the ... OCD, PTSD, and related disorders. Find a Therapist Stress Relief Kits Feeling stressed? Get an ADAA stress ...

  3. Tips for Teens with Diabetes: About Diabetes

    Science.gov (United States)

    National Diabetes Education Program (NDEP), 2010

    2010-01-01

    Diabetes is a serious disease. It means that one's blood glucose, also called blood sugar, is too high. Having too much glucose in a person's blood is not healthy. This paper offers tips for managing diabetes.

  4. Food Safety Tips for College Students

    Science.gov (United States)

    ... Standard Forms FSIS United States Department of Agriculture Food Safety and Inspection Service About FSIS District Offices ... Web Content Viewer (JSR 286) Actions ${title} Loading... Food Safety Tips for College Students When students pack ...

  5. Essential Outdoor Sun Safety Tips for Winter

    Science.gov (United States)

    ... Weekend Warriors expand/collapse Vitamin D Essential Outdoor Sun Safety Tips for Winter Winter sports enthusiasts are ... skiing! Be Mindful of Time Spent in the Sun, Regardless of the Season If possible, ski early ...

  6. Health Tip: Know Your Risk for Obesity

    Science.gov (United States)

    ... 166114.html Health Tip: Know Your Risk for Obesity Here's what makes it more likely To use ... Diana Kohnle Wednesday, May 31, 2017 (HealthDay News) -- Obesity is linked to an increased risk for heart ...

  7. Alzheimer's: 7 Tips for Medical Visits

    Science.gov (United States)

    ... Regular medical care is an important part of Alzheimer's treatment. Use these seven tips to stay on ... Clinic staff People who have dementia due to Alzheimer's disease need regular medical care to address a ...

  8. Quick Tips Guide for Small Manufacturing Businesses

    Science.gov (United States)

    Small manufacturing businesses can use this Quick Tips Guide to be better prepared for future extreme weather events. This guide discusses keeping good records, improving housekeeping procedures, and training employees.

  9. Children Health Tips in Other Languages

    Science.gov (United States)

    These tips for protecting children from environmental risks/exposures are available in spanish, chinese, vietnamese, and korean. They cover topics such as lead, pesticides, carbon monoxide, air pollution, drinking water contaminants, and radon.

  10. Barbecue Basics: Tips to Prevent Foodborne Illness

    Medline Plus

    Full Text Available ... Home For Consumers Consumer Updates Barbecue Basics: Tips to Prevent Foodborne Illness Share Tweet Linkedin Pin it ... are a lot of steps consumers can take to keep family and friends from becoming ill,” says ...

  11. Sleep Tips: 7 Steps to Better Sleep

    Science.gov (United States)

    ... turn every night. Consider simple tips for better sleep, from setting a sleep schedule to including physical activity in your daily ... factors that can interfere with a good night's sleep — from work stress and family responsibilities to unexpected ...

  12. Can't sleep? Try these tips

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/patientinstructions/000853.htm Can't sleep? Try these tips To use the sharing ... with your daily activities. References Adams SK, Kisler TS. Sleep quality as a mediator between technology-related ...

  13. Practical Tips to Hack your NGO

    OpenAIRE

    Pedro Marcun

    2012-01-01

    Pedro Marcun provides some useful tips to make NGOs work, from sharing data, to being accountable and to using all the possible tools on the internet. Only in this way, will NGOs survive in an interconnected world.

  14. CFD analysis of cloud cavitation on three tip-modified propellers with systematically varied tip geometry

    DEFF Research Database (Denmark)

    Shin, K. W.; Andersen, Poul

    2015-01-01

    The blade tip loading is often reduced as an effort to restrain sheet and tip vortex cavitation in the design of marine propellers. This CFD analysis demonstrates that an excessive reduction of the tip loading can cause cloud cavitation responsible for much of noise and surface erosion. Detached...... eddy simulations (DES) are made for cavitating flows on three tip- modified propellers, of which one is a reference propeller having an experimental result from a cavitation tunnel test with a hull model, and the other two are modified from the reference propeller by altering the blade tip loading. DES...... results have been validated against the experiment in terms of sheet and cloud cavitation. In DES, non-uniform hull wake is modelled by using the inlet flow and momentum sources instead of including a hull model. A 4-bladed Kappel propeller with a smooth tip bending towards the suction side is used...

  15. Silicon Micromachined Sensor for Broadband Vibration Analysis

    Science.gov (United States)

    Gutierrez, Adolfo; Edmans, Daniel; Cormeau, Chris; Seidler, Gernot; Deangelis, Dave; Maby, Edward

    1995-01-01

    The development of a family of silicon based integrated vibration sensors capable of sensing mechanical resonances over a broad range of frequencies with minimal signal processing requirements is presented. Two basic general embodiments of the concept were designed and fabricated. The first design was structured around an array of cantilever beams and fabricated using the ARPA sponsored multi-user MEMS processing system (MUMPS) process at the Microelectronics Center of North Carolina (MCNC). As part of the design process for this first sensor, a comprehensive finite elements analysis of the resonant modes and stress distribution was performed using PATRAN. The dependence of strain distribution and resonant frequency response as a function of Young's modulus in the Poly-Si structural material was studied. Analytical models were also studied. In-house experimental characterization using optical interferometry techniques were performed under controlled low pressure conditions. A second design, intended to operate in a non-resonant mode and capable of broadband frequency response, was proposed and developed around the concept of a cantilever beam integrated with a feedback control loop to produce a null mode vibration sensor. A proprietary process was used to integrat a metal-oxide semiconductor (MOS) sensing device, with actuators and a cantilever beam, as part of a compatible process. Both devices, once incorporated as part of multifunction data acquisition and telemetry systems will constitute a useful system for NASA launch vibration monitoring operations. Satellite and other space structures can benefit from the sensor for mechanical condition monitoring functions.

  16. The Give and Take on Restaurant Tipping

    OpenAIRE

    Parrett, Matthew Barton

    2003-01-01

    This dissertation examines aspects of both the consumer (the "give") and the server (the "take") sides of restaurant tipping. On the consumer side, I address both why, and how much, people tip in restaurants. I also examine a policy issue related to the recent Supreme Court decision in United States v. Fior d'Italia. These issues are addressed via a combination of theoretical, empirical, and experimental analysis. On the server side, I use survey data collected from several restaurants...

  17. Tipping the balance: robustness of tip cell selection, migration and fusion in angiogenesis.

    Directory of Open Access Journals (Sweden)

    Katie Bentley

    2009-10-01

    Full Text Available Vascular abnormalities contribute to many diseases such as cancer and diabetic retinopathy. In angiogenesis new blood vessels, headed by a migrating tip cell, sprout from pre-existing vessels in response to signals, e.g., vascular endothelial growth factor (VEGF. Tip cells meet and fuse (anastomosis to form blood-flow supporting loops. Tip cell selection is achieved by Dll4-Notch mediated lateral inhibition resulting, under normal conditions, in an interleaved arrangement of tip and non-migrating stalk cells. Previously, we showed that the increased VEGF levels found in many diseases can cause the delayed negative feedback of lateral inhibition to produce abnormal oscillations of tip/stalk cell fates. Here we describe the development and implementation of a novel physics-based hierarchical agent model, tightly coupled to in vivo data, to explore the system dynamics as perpetual lateral inhibition combines with tip cell migration and fusion. We explore the tipping point between normal and abnormal sprouting as VEGF increases. A novel filopodia-adhesion driven migration mechanism is presented and validated against in vivo data. Due to the unique feature of ongoing lateral inhibition, 'stabilised' tip/stalk cell patterns show sensitivity to the formation of new cell-cell junctions during fusion: we predict cell fates can reverse. The fusing tip cells become inhibited and neighbouring stalk cells flip fate, recursively providing new tip cells. Junction size emerges as a key factor in establishing a stable tip/stalk pattern. Cell-cell junctions elongate as tip cells migrate, which is shown to provide positive feedback to lateral inhibition, causing it to be more susceptible to pathological oscillations. Importantly, down-regulation of the migratory pathway alone is shown to be sufficient to rescue the sprouting system from oscillation and restore stability. Thus we suggest the use of migration inhibitors as therapeutic agents for vascular

  18. Tipping the balance: robustness of tip cell selection, migration and fusion in angiogenesis.

    Science.gov (United States)

    Bentley, Katie; Mariggi, Giovanni; Gerhardt, Holger; Bates, Paul A

    2009-10-01

    Vascular abnormalities contribute to many diseases such as cancer and diabetic retinopathy. In angiogenesis new blood vessels, headed by a migrating tip cell, sprout from pre-existing vessels in response to signals, e.g., vascular endothelial growth factor (VEGF). Tip cells meet and fuse (anastomosis) to form blood-flow supporting loops. Tip cell selection is achieved by Dll4-Notch mediated lateral inhibition resulting, under normal conditions, in an interleaved arrangement of tip and non-migrating stalk cells. Previously, we showed that the increased VEGF levels found in many diseases can cause the delayed negative feedback of lateral inhibition to produce abnormal oscillations of tip/stalk cell fates. Here we describe the development and implementation of a novel physics-based hierarchical agent model, tightly coupled to in vivo data, to explore the system dynamics as perpetual lateral inhibition combines with tip cell migration and fusion. We explore the tipping point between normal and abnormal sprouting as VEGF increases. A novel filopodia-adhesion driven migration mechanism is presented and validated against in vivo data. Due to the unique feature of ongoing lateral inhibition, 'stabilised' tip/stalk cell patterns show sensitivity to the formation of new cell-cell junctions during fusion: we predict cell fates can reverse. The fusing tip cells become inhibited and neighbouring stalk cells flip fate, recursively providing new tip cells. Junction size emerges as a key factor in establishing a stable tip/stalk pattern. Cell-cell junctions elongate as tip cells migrate, which is shown to provide positive feedback to lateral inhibition, causing it to be more susceptible to pathological oscillations. Importantly, down-regulation of the migratory pathway alone is shown to be sufficient to rescue the sprouting system from oscillation and restore stability. Thus we suggest the use of migration inhibitors as therapeutic agents for vascular normalisation in cancer.

  19. The tipping point: a mathematical model for the profit-driven abandonment of restaurant tipping

    OpenAIRE

    Clifton, Sara M.; Herbers, Eileen; Chen, Jack; Abrams, Daniel M.

    2017-01-01

    The custom of voluntarily tipping for services rendered has gone in and out of fashion in America since its introduction in the 19th century. Restaurant owners that ban tipping in their establishments often claim that social justice drives their decisions, but we show that rational profit-maximization may also justify the decisions. Here, we propose a conceptual model of restaurant competition for staff and customers, and we show that there exists a critical conventional tip rate at which res...

  20. The anatomy of the bill tip of kiwi and associated somatosensory regions of the brain: comparisons with shorebirds.

    Directory of Open Access Journals (Sweden)

    Susan J Cunningham

    Full Text Available Three families of probe-foraging birds, Scolopacidae (sandpipers and snipes, Apterygidae (kiwi, and Threskiornithidae (ibises, including spoonbills have independently evolved long, narrow bills containing clusters of vibration-sensitive mechanoreceptors (Herbst corpuscles within pits in the bill-tip. These 'bill-tip organs' allow birds to detect buried or submerged prey via substrate-borne vibrations and/or interstitial pressure gradients. Shorebirds, kiwi and ibises are only distantly related, with the phylogenetic divide between kiwi and the other two taxa being particularly deep. We compared the bill-tip structure and associated somatosensory regions in the brains of kiwi and shorebirds to understand the degree of convergence of these systems between the two taxa. For comparison, we also included data from other taxa including waterfowl (Anatidae and parrots (Psittaculidae and Cacatuidae, non-apterygid ratites, and other probe-foraging and non probe-foraging birds including non-scolopacid shorebirds (Charadriidae, Haematopodidae, Recurvirostridae and Sternidae. We show that the bill-tip organ structure was broadly similar between the Apterygidae and Scolopacidae, however some inter-specific variation was found in the number, shape and orientation of sensory pits between the two groups. Kiwi, scolopacid shorebirds, waterfowl and parrots all shared hypertrophy or near-hypertrophy of the principal sensory trigeminal nucleus. Hypertrophy of the nucleus basorostralis, however, occurred only in waterfowl, kiwi, three of the scolopacid species examined and a species of oystercatcher (Charadriiformes: Haematopodidae. Hypertrophy of the principal sensory trigeminal nucleus in kiwi, Scolopacidae, and other tactile specialists appears to have co-evolved alongside bill-tip specializations, whereas hypertrophy of nucleus basorostralis may be influenced to a greater extent by other sensory inputs. We suggest that similarities between kiwi and scolopacid

  1. The anatomy of the bill tip of kiwi and associated somatosensory regions of the brain: comparisons with shorebirds.

    Science.gov (United States)

    Cunningham, Susan J; Corfield, Jeremy R; Iwaniuk, Andrew N; Castro, Isabel; Alley, Maurice R; Birkhead, Tim R; Parsons, Stuart

    2013-01-01

    Three families of probe-foraging birds, Scolopacidae (sandpipers and snipes), Apterygidae (kiwi), and Threskiornithidae (ibises, including spoonbills) have independently evolved long, narrow bills containing clusters of vibration-sensitive mechanoreceptors (Herbst corpuscles) within pits in the bill-tip. These 'bill-tip organs' allow birds to detect buried or submerged prey via substrate-borne vibrations and/or interstitial pressure gradients. Shorebirds, kiwi and ibises are only distantly related, with the phylogenetic divide between kiwi and the other two taxa being particularly deep. We compared the bill-tip structure and associated somatosensory regions in the brains of kiwi and shorebirds to understand the degree of convergence of these systems between the two taxa. For comparison, we also included data from other taxa including waterfowl (Anatidae) and parrots (Psittaculidae and Cacatuidae), non-apterygid ratites, and other probe-foraging and non probe-foraging birds including non-scolopacid shorebirds (Charadriidae, Haematopodidae, Recurvirostridae and Sternidae). We show that the bill-tip organ structure was broadly similar between the Apterygidae and Scolopacidae, however some inter-specific variation was found in the number, shape and orientation of sensory pits between the two groups. Kiwi, scolopacid shorebirds, waterfowl and parrots all shared hypertrophy or near-hypertrophy of the principal sensory trigeminal nucleus. Hypertrophy of the nucleus basorostralis, however, occurred only in waterfowl, kiwi, three of the scolopacid species examined and a species of oystercatcher (Charadriiformes: Haematopodidae). Hypertrophy of the principal sensory trigeminal nucleus in kiwi, Scolopacidae, and other tactile specialists appears to have co-evolved alongside bill-tip specializations, whereas hypertrophy of nucleus basorostralis may be influenced to a greater extent by other sensory inputs. We suggest that similarities between kiwi and scolopacid bill-tip

  2. Finite-temperature hydrogen adsorption and desorption thermodynamics driven by soft vibration modes.

    Science.gov (United States)

    Woo, Sung-Jae; Lee, Eui-Sup; Yoon, Mina; Kim, Yong-Hyun

    2013-08-09

    It has been widely accepted that enhanced dihydrogen adsorption is required for room-temperature hydrogen storage on nanostructured porous materials. Here we report, based on results of first-principles total energy and vibrational spectrum calculations, finite-temperature adsorption and desorption thermodynamics of hydrogen molecules that are adsorbed on the metal center of metal-porphyrin-incorporated graphene. We have revealed that the room-temperature hydrogen storage is achievable not only with the enhanced adsorption enthalpy, but also with soft-mode driven vibrational entropy of the adsorbed dihydrogen molecule. The soft vibration modes mostly result from multiple orbital coupling between the hydrogen molecule and the buckled metal center, for example, in Ca-porphyrin-incorporated graphene. Our study suggests that the current design strategy for room-temperature hydrogen storage materials should be modified with explicitly taking the finite-temperature vibration thermodynamics into account.

  3. [Effect of vibration, noise, physical exertion and unfavorable microclimate on carbohydrate metabolism in workers engaged into mining industry and machine building].

    Science.gov (United States)

    Lapko, I V; Kir'iakov, V A; Antoshina, L I; Pavlovskaia, N A; Kondratovich, S V

    2014-01-01

    The authors studied influence of vibration, noise, physical overexertion and microclimate on carbohydrates metabolism and insulin resistance in metal mining industry workers. Findings are that vibration disease appeared to have maximal effect on insulin resistance test results and insulin level. The authors suggested biomarkers for early diagnosis of insulin resistance disorders in metal mining industry workers.

  4. Vibration-assisted machining of single crystal

    Science.gov (United States)

    Zahedi, S. A.; Roy, A.; Silberschmidt, V. V.

    2013-07-01

    Vibration-assisted machining offers a solution to expanding needs for improved machining, especially where accuracy and precision are of importance, such as in micromachining of single crystals of metals and alloys. Crystallographic anisotropy plays a crucial role in determining on overall response to machining. In this study, we intend to address the matter of ultra-precision machining of material at the micron scale using computational modelling. A hybrid modelling approach is implemented that combines two discrete schemes: smoothed particle hydrodynamics and continuum finite elements. The model is implemented in a commercial software ABAQUS/Explicit employing a user-defined subroutine (VUMAT) and used to elucidate the effect of crystallographic anisotropy on a response of face centred cubic (f.c.c.) metals to machining.

  5. Investigation into high-frequency-vibration assisted micro-blanking of pure copper foils

    Directory of Open Access Journals (Sweden)

    Wang Chunju

    2015-01-01

    Full Text Available The difficulties encountered during the manufacture of microparts are often associated with size effects relating to material, process and tooling. Utilizing acoustoplastic softening, achieved through a high-frequency vibration assisted micro-blanking process, was introduced to improve the surface finish in micro-blanking. A frequency of 1.0 kHz was chosen to activate the longitudinal vibration mode of the horn tip, using a piezoelectric actuator. A square hole with dimensions of 0.5 mm × 0.5 mm was made, successfully, from a commercial rolled T2 copper foil with 100 μm in thickness. It was found that the maximum blanking force could be reduced by 5% through utilizing the high-frequency vibration. Proportion of the smooth, burnished area in the cut cross-section increases with an increase of the plasticity to fracture, under the high-frequency vibration, which suggests that the vibration introduced is helpful for inhibiting evolution of the crack due to its acoustoplastic softening effect. During blanking, roughness of the burnished surface could be reduced by increasing the vibration amplitude of the punch, which played a role as surface polishing. The results obtained suggest that the high-frequency vibration can be adopted in micro-blanking in order to improve quality of the microparts.

  6. VIBRATION ISOLATION SYSTEM PROBABILITY ANALYSIS

    Directory of Open Access Journals (Sweden)

    Smirnov Vladimir Alexandrovich

    2012-10-01

    Full Text Available The article deals with the probability analysis for a vibration isolation system of high-precision equipment, which is extremely sensitive to low-frequency oscillations even of submicron amplitude. The external sources of low-frequency vibrations may include the natural city background or internal low-frequency sources inside buildings (pedestrian activity, HVAC. Taking Gauss distribution into account, the author estimates the probability of the relative displacement of the isolated mass being still lower than the vibration criteria. This problem is being solved in the three dimensional space, evolved by the system parameters, including damping and natural frequency. According to this probability distribution, the chance of exceeding the vibration criteria for a vibration isolation system is evaluated. Optimal system parameters - damping and natural frequency - are being developed, thus the possibility of exceeding vibration criteria VC-E and VC-D is assumed to be less than 0.04.

  7. Random vibrations theory and practice

    CERN Document Server

    Wirsching, Paul H; Ortiz, Keith

    1995-01-01

    Random Vibrations: Theory and Practice covers the theory and analysis of mechanical and structural systems undergoing random oscillations due to any number of phenomena— from engine noise, turbulent flow, and acoustic noise to wind, ocean waves, earthquakes, and rough pavement. For systems operating in such environments, a random vibration analysis is essential to the safety and reliability of the system. By far the most comprehensive text available on random vibrations, Random Vibrations: Theory and Practice is designed for readers who are new to the subject as well as those who are familiar with the fundamentals and wish to study a particular topic or use the text as an authoritative reference. It is divided into three major sections: fundamental background, random vibration development and applications to design, and random signal analysis. Introductory chapters cover topics in probability, statistics, and random processes that prepare the reader for the development of the theory of random vibrations a...

  8. Intermetallic Cu3Sn Phase Layer on Electrode’s Tip of Galvanized Resistance Spot Welding

    Directory of Open Access Journals (Sweden)

    Muhammad Anis

    2010-10-01

    Full Text Available A resistance spot welding method is commonly used in automotive industries application. In a resistance spot welding method, the copper electrode has a significant role as an electric current carrier for joining thin metal sheet. This research was focused on studying the effect of tin layer at the electrode tip for joining galvanized steel sheet. The main variable of this research is in the thickness of the intermetallic Cu3Sn layer. The result showed that the introduction of tin layer less than 1 μm in thickness on the electrode tip gives a comparable shear strength and nugget diameter distribution with the unplated electrode tip.

  9. A Class of Methods for the Analysis of Blade Tip Timing Data from Bladed Assemblies Undergoing Simultaneous Resonances—Part II: Experimental Validation

    Directory of Open Access Journals (Sweden)

    J. Gallego-Garrido

    2007-01-01

    Full Text Available Blade tip timing is a technique for the measurement of vibrations in rotating bladed assemblies. In Part I of this work a class of methods for the analysis of blade tip timing data from bladed assemblies undergoing two simultaneous synchronous resonances was developed. The approaches were demonstrated using data from a mathematical simulation of tip timing data. In Part II the methods are validated on an experimental test rig. First, the construction and characteristics of the rig will be discussed. Then, the performance of the analysis techniques when applied to data from the rig will be compared and analysed. It is shown that accurate frequency estimates are obtained by all the methods for both single and double resonances. Furthermore, the recovered frequencies are used to calculate the amplitudes of the blade tip responses. The presence of mistuning in the bladed assembly does not affect the performance of the new techniques.

  10. Laboratory and workplace assessments of rivet bucking bar vibration emissions.

    Science.gov (United States)

    McDowell, Thomas W; Warren, Christopher; Xu, Xueyan S; Welcome, Daniel E; Dong, Ren G

    2015-04-01

    Sheet metal workers operating rivet bucking bars are at risk of developing hand and wrist musculoskeletal disorders associated with exposures to hand-transmitted vibrations and forceful exertions required to operate these hand tools. New bucking bar technologies have been introduced in efforts to reduce workplace vibration exposures to these workers. However, the efficacy of these new bucking bar designs has not been well documented. While there are standardized laboratory-based methodologies for assessing the vibration emissions of many types of powered hand tools, no such standard exists for rivet bucking bars. Therefore, this study included the development of a laboratory-based method for assessing bucking bar vibrations which utilizes a simulated riveting task. With this method, this study evaluated three traditional steel bucking bars, three similarly shaped tungsten alloy bars, and three bars featuring spring-dampeners. For comparison the bucking bar vibrations were also assessed during three typical riveting tasks at a large aircraft maintenance facility. The bucking bars were rank-ordered in terms of unweighted and frequency-weighted acceleration measured at the hand-tool interface. The results suggest that the developed laboratory method is a reasonable technique for ranking bucking bar vibration emissions; the lab-based riveting simulations produced similar rankings to the workplace rankings. However, the laboratory-based acceleration averages were considerably lower than the workplace measurements. These observations suggest that the laboratory test results are acceptable for comparing and screening bucking bars, but the laboratory measurements should not be directly used for assessing the risk of workplace bucking bar vibration exposures. The newer bucking bar technologies exhibited significantly reduced vibrations compared to the traditional steel bars. The results of this study, together with other information such as rivet quality, productivity, tool

  11. The origins of a wind turbine tip vortex

    NARCIS (Netherlands)

    Micallef, D.; Akay, B.; Simao Ferreira, C.J.; Sant, T.; Van Bussel, G.J.W.

    2014-01-01

    The tip vortex of a wind turbine rotor blade originates as a result of a complex distribution of vorticity along the blade tip thickness. While the tip vortex evolution was extensively studied previously in other work, the mechanism of the initiation of the tip vorticity in a 3D rotating environment

  12. Validation of Tip Corrections for Wind Turbine computations

    DEFF Research Database (Denmark)

    Shen, Wen Zhong; Mikkelsen, Robert; Sørensen, Jens Nørkær

    2003-01-01

    Tip loss effect of rotors plays an important role in predictions of wind turbine performance. Classical tip corrections, based on the Prandtl tip reduction function, including Glauert´, Wilson & Lissaman´s and De Vries´ corrections are considered in the paper. In the proximity of the tip...

  13. Model Based Metal Transfer Control

    DEFF Research Database (Denmark)

    Thomsen, Jesper Sandberg

    2006-01-01

    In pulsed gas metal arc welding (pulsed GMAW) current pulses are used for detaching drops at the tip of the electrode. To obtain a high weld quality one drop should be detached for every pulse, and moreover, the amount of energy used for detachment should be kept at a minimum. Thus, each pulse mu...

  14. Chaotic vortex induced vibrations

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, J.; Sheridan, J. [Fluids Laboratory for Aeronautical and Industrial Research (FLAIR), Department of Mechanical and Aerospace Engineering, Monash University, Melbourne, Victoria 3800 (Australia); Leontini, J. S. [Department of Mechanical and Product Design Engineering, Swinburne University of Technology, Hawthorn, Victoria 3122 (Australia); Lo Jacono, D. [Institut de Mécanique des Fluides de Toulouse (IMFT), CNRS, UPS and Université de Toulouse, 31400 Toulouse (France)

    2014-12-15

    This study investigates the nature of the dynamic response of an elastically mounted cylinder immersed in a free stream. A novel method is utilized, where the motion of the body during a free vibration experiment is accurately recorded, and then a second experiment is conducted where the cylinder is externally forced to follow this recorded trajectory. Generally, the flow response during both experiments is identical. However, particular regimes exist where the flow response is significantly different. This is taken as evidence of chaos in these regimes.

  15. Lattice Vibrations in Chlorobenzenes:

    DEFF Research Database (Denmark)

    Reynolds, P. A.; Kjems, Jørgen; White, J. W.

    1974-01-01

    Lattice vibrational dispersion curves for the ``intermolecular'' modes in the triclinic, one molecule per unit cell β phase of p‐C6D4Cl2 and p‐C6H4Cl2 have been obtained by inelastic neutron scattering. The deuterated sample was investigated at 295 and at 90°K and a linear extrapolation to 0°K...... was applied in order to correct for anharmonic effects. Calculations based on the atom‐atom model for van der Waals' interaction and on general potential parameters for the aromatic compounds agree reasonably well with the experimental observations. There is no substantial improvement in fit obtained either...

  16. 26 CFR 31.3401(f)-1 - Tips.

    Science.gov (United States)

    2010-04-01

    ... 26 Internal Revenue 15 2010-04-01 2010-04-01 false Tips. 31.3401(f)-1 Section 31.3401(f)-1... Income Tax at Source § 31.3401(f)-1 Tips. (a) Tips considered wages. Tips received after 1965 by an... income tax at source. For an exception to the rule that tips constitute wages, see §§ 31.3401(a)(16) and...

  17. 26 CFR 31.3121(a)(12)-1 - Tips.

    Science.gov (United States)

    2010-04-01

    ... 26 Internal Revenue 15 2010-04-01 2010-04-01 false Tips. 31.3121(a)(12)-1 Section 31.3121(a)(12)-1... Contributions Act (Chapter 21, Internal Revenue Code of 1954) General Provisions § 31.3121(a)(12)-1 Tips. The... tips if— (a) The tips are paid in any medium other than cash, or (b) The cash tips received by an...

  18. Quantum dynamics of vibrational excitations and vibrational charge ...

    Indian Academy of Sciences (India)

    Quantum dynamics of vibrational excitations and vibrational charge transfer processes in H+ + O2 collisions at collision energy 23 eV ... The Fritz Haber Research Centre and The Department of Physical Chemisry, Hebrew University of Jerusalem, Jerusalem, Israel 91904; Department of Chemistry, Indian Institute of ...

  19. 78 FR 13402 - Proposed Collection; Comment Request for Tip Reporting Alternative Tip Agreement Used in the...

    Science.gov (United States)

    2013-02-27

    ... Used in the Cosmetology and Barber Industry AGENCY: Internal Revenue Service (IRS), Treasury. ACTION..., the IRS is soliciting comments concerning tip reporting alternative commitment used in the cosmetology...: Tip Reporting Alternative Commitment Agreement used in the Cosmetology and Barber Industry. OMB Number...

  20. 75 FR 11226 - Proposed Collection; Comment Request for Tip Reporting Alternative Tip Agreement Used in the...

    Science.gov (United States)

    2010-03-10

    ... Used in the Cosmetology and Barber Industry AGENCY: Internal Revenue Service (IRS), Treasury. ACTION..., the IRS is soliciting comments concerning Tip Reporting Alternative Commitment used in the Cosmetology...: Tip Reporting Alternative Commitment Agreement used in the Cosmetology and Barber Industry. OMB Number...

  1. Optimal ossicular site for maximal vibration transmissions to coupled transducers.

    Science.gov (United States)

    Chung, Juyong; Song, Won Joon; Sim, Jae Hoon; Kim, Wandoo; Oh, Seung-Ha

    2013-07-01

    Totally implantable middle-ear prosthetic devices, such as the Esteem system (Envoy Medical Corporation), detect vibrational motion of the middle-ear ossicles rather than acoustic stimulation to the eardrum. This eliminates the need for a subcutaneous microphone, which is susceptible to interference by ambient noises. Study of the vibrational characteristics of the human ossicles provides valuable information for determining the site of maximum ossicular motion that would be optimal for attachment of the sensor portion of the prosthesis. In this study, vibrational responses at seven locations on the middle-ear ossicles (i.e., the malleus head, 4 different points on the incus body, middle of the incus long process, tip of the incus long process) in human temporal bones (n = 6) were measured using a laser Doppler vibrometer. The measurements were repeated after separating the incudostapedial joint (ISJ). Measured displacement at each location was normalized with the sound pressure level near the tympanic membrane (TM) for representation in the form of a displacement transfer function (DTF). The normalized squared sum of the DTFs (NSSDTF) was then calculated as a measure of vibration motion through a specific frequency range at the considered sites. The relatively large NSSDTF was observed at the sites on the superior part of the malleus head (MH), on the lateral part of the incus body (IBL), and on the superior part of the incus body near the incudomalleal joint (IBS1) for the frequency ranges of 1-4 kHz and 1-9 kHz, regardless of the condition of the ISJ. This indicates that maximum vibrational motion of the middle-ear is deliverable to the piezoelectric transducer of totally implantable devices through these sites. This article is part of a special issue entitled "MEMRO 2012". Copyright © 2013 Elsevier B.V. All rights reserved.

  2. Design and Development of Electro-Mechanical Twins Tipping Buckets Runoff-Meter

    Directory of Open Access Journals (Sweden)

    Olotu Yahaya

    2014-07-01

    Full Text Available Electro-mechanical tipping bucket runoff-meter was designed and developed to measure surface runoff water using locally-sourced components. The instrument consists of metallic-fabricated runoff plot area of 2 m 2 , depth 0.25 m and metal gauge of 3mm. The tipping operation was initiated by arranging the sensitive electro-mechanical components such digital micro-switch (SW1,SW2, SW3 and SW4, pair of open/close circuit breakers (No,Nc, electronic speed gear and circular rotating disc to a pair of twins buckets of runoff volume 0.141 liter capacity per bucket which corresponds to 0.25 mm runoff depth. The whole arrangement was powered by a 12V by 75 AH battery and the tipping processes was being recorded by the electro-mechanical data logger. The instrument has a measuring accuracy of ±0.001 liter per tip. It was calibrated to measure minimum and maximum runoff volume from 0.14l to 200 liters, these values correspond to 0.25 mm and 800 mm runoff depths respectively. Therefore, precise results obtained using the instrument could be used to establish strong database for measuring and storing accurate surface runoff data which in turn could be applied for hydrological modeling for sustainable water resources management and design of hydraulic structures

  3. Harvesting vibrational energy with liquid-bridged electrodes: thermodynamics in mechanically and electrically driven RC-circuits

    NARCIS (Netherlands)

    Janssen, Mathijs; Werkhoven, Ben; Van Roij, René

    2016-01-01

    We theoretically study a vibrating pair of parallel electrodes bridged by a (deformed) liquid droplet, which is a recently developed microfluidic device to harvest vibrational energy. The device can operate with various liquids, including liquid metals, electrolytes, as well as ionic liquids. We

  4. Literature survey on anti-vibration gloves

    CSIR Research Space (South Africa)

    Sampson, E

    2003-08-01

    Full Text Available ............................................................................................................... 1 2. HAND ARM VIBRATION SYNDROME (HAVS).......................................................... 2 2.1 Hand-arm vibration................................................. Error! Bookmark not defined. 2.2 Human Response to vibration...

  5. Vibrational Sensing in Marine Invertebrates

    Science.gov (United States)

    1997-09-30

    VIBRATIONAL SENSING IN MARINE INVERTEBRATES Peter A. Jumars School of Oceanography University of Washington Box 357940 Seattle, WA 98195-7940 (206...DATES COVERED 00-00-1997 to 00-00-1997 4. TITLE AND SUBTITLE Vibrational Sensing in Marine Invertebrates 5a. CONTRACT NUMBER 5b. GRANT NUMBER

  6. Vibrations and Stability: Solved Problems

    DEFF Research Database (Denmark)

    Thomsen, Jon Juel

    Worked out solutions for exercise problems in J. J. Thomsen 'Vibrations and Stability: Advanced Theory, Analysis, and Tools', Springer, Berlin - Heidelberg, 2003.......Worked out solutions for exercise problems in J. J. Thomsen 'Vibrations and Stability: Advanced Theory, Analysis, and Tools', Springer, Berlin - Heidelberg, 2003....

  7. Evaluation of crack tip constraint using photoelasticity

    Energy Technology Data Exchange (ETDEWEB)

    Ayatollahi, M.R.; Safari, H

    2003-09-01

    The method of photoelasticity has been used extensively in the past for investigating elastic stresses in cracked specimens. However, previous studies concentrate predominantly on different methods for determining the stress intensity factors. Some of these methods make use of the higher order stress terms including the T-stress to achieve more accurate experimental results for stress intensity factors. Nevertheless, the effect of T-stress on the stress fields near the crack tip has received little attention in previous photoelastic studies. In this paper, a two-parameter formulation is used to study how the T-stress influences the isochromatic fringe patterns around the tip of a mode I crack. Theoretical and experimental results obtained in this research show that the isochromatic fringes near the crack tip rotate forward and backward for negative and positive values of T-stress, respectively. Therefore, the experimental technique of photoelasticity can be used to distinguish low constraint cracked components from high constraint ones.

  8. Tip vortices in the actuator line model

    Science.gov (United States)

    Martinez, Luis; Meneveau, Charles

    2017-11-01

    The actuator line model (ALM) is a widely used tool to represent the wind turbine blades in computational fluid dynamics without the need to resolve the full geometry of the blades. The ALM can be optimized to represent the `correct' aerodynamics of the blades by choosing an appropriate smearing length scale ɛ. This appropriate length scale creates a tip vortex which induces a downwash near the tip of the blade. A theoretical frame-work is used to establish a solution to the induced velocity created by a tip vortex as a function of the smearing length scale ɛ. A correction is presented which allows the use of a non-optimal smearing length scale but still provides the downwash which would be induced using the optimal length scale. Thanks to the National Science Foundation (NSF) who provided financial support for this research via Grants IGERT 0801471, IIA-1243482 (the WINDINSPIRE project) and ECCS-1230788.

  9. Tipping elements in the Arctic marine ecosystem.

    Science.gov (United States)

    Duarte, Carlos M; Agustí, Susana; Wassmann, Paul; Arrieta, Jesús M; Alcaraz, Miquel; Coello, Alexandra; Marbà, Núria; Hendriks, Iris E; Holding, Johnna; García-Zarandona, Iñigo; Kritzberg, Emma; Vaqué, Dolors

    2012-02-01

    The Arctic marine ecosystem contains multiple elements that present alternative states. The most obvious of which is an Arctic Ocean largely covered by an ice sheet in summer versus one largely devoid of such cover. Ecosystems under pressure typically shift between such alternative states in an abrupt, rather than smooth manner, with the level of forcing required for shifting this status termed threshold or tipping point. Loss of Arctic ice due to anthropogenic climate change is accelerating, with the extent of Arctic sea ice displaying increased variance at present, a leading indicator of the proximity of a possible tipping point. Reduced ice extent is expected, in turn, to trigger a number of additional tipping elements, physical, chemical, and biological, in motion, with potentially large impacts on the Arctic marine ecosystem.

  10. Magnetic vortices induced by a moving tip

    Science.gov (United States)

    Magiera, Martin P.; Hucht, Alfred; Wolf, Dietrich E.

    2013-03-01

    A two-dimensional easy-plane ferromagnetic substrate interacting with a dipolar tip which is magnetized perpendicular with respect to the easy plane is studied numerically by solving the Landau-Lifshitz Gilbert equation [Europhys. Lett. 100, 27004 (2012)]. Due to the symmetry of the dipolar field of the tip, in addition to the collinear structure a magnetic vortex structure becomes stable. It is robust against excitations caused by the motion of the tip. The moved vortex structure shows an increased energy dissipation compared to the collinear structure. We show that for high excitations the system may perform a transition between the two states. The influence of domain walls, which may also induce this transition, is examined. Financial support by the German Research Foundation (DFG) through SFB 616 ``Energy Dissipation at Surfaces'' and the German Exchange Association (DAAD) through the Project Related Exchange Brazil-Germany (PROBRAL) is acknowledged.

  11. Protected Plasmonic Nanostructures for High Resolution Chemical Imaging using Tip Enhanced Raman Spectroscopy

    Science.gov (United States)

    Butt, Rebecca; Barrios, Carlos; Malkovskiy, Andrey; Kisliuk, Alexander; Sokolov, Alexei; Foster, Mark

    2009-03-01

    Tip enhanced Raman spectroscopy (TERS), an emerging technique that combines optical microscopy and scanning probe microscopy, provides the sensitivity and selectivity necessary for high-resolution chemical imaging of polymer surfaces. An unprecedented 20 nm lateral resolution for the chemical imaging has been achieved. Unfortunately, the fragile plasmonic structures used to enhance the electric field are prone to mechanical, chemical, and thermal degradation. Developing robust noble metal nanostructures with stable plasmonic resonance is essential to reliable high resolution chemical imaging. Covering the metal layer with organic and inorganic ultrathin coatings is being investigated to extend the plasmonic activity of the engineered nanostructures. Addition of an ultrathin aluminum oxide (Al2O3) coating to a silver-coated scanning probe microscopy tip for TERS significantly improves plasmonic structure stability without sacrificing the initial TERS efficiency. This ultrathin coating provides wear resistance and stops chemical degradation responsible for the loss of signal enhancement.

  12. The origins of vibration theory

    Science.gov (United States)

    Dimarogonas, A. D.

    1990-07-01

    The Ionian School of natural philosophy introduced the scientific method of dealing with natural phenomena and the rigorous proofs for abstract propositions. Vibration theory was initiated by the Pythagoreans in the fifth century BC, in association with the theory of music and the theory of acoustics. They observed the natural frequency of vibrating systems and proved that it is a system property and that it does not depend on the excitation. Pythagoreans determined the fundamental natural frequencies of several simple systems, such as vibrating strings, pipes, vessels and circular plates. Aristoteles and the Peripatetic School founded mechanics and developed a fundamental understanding of statics and dynamics. In Alexandrian times there were substantial engineering developments in the field of vibration. The pendulum as a vibration, and probably time, measuring device was known in antiquity, and was further developed by the end of the first millennium AD.

  13. Twelve tips for supervising research students.

    Science.gov (United States)

    Siddiqui, Zarrin Seema; Jonas-Dwyer, Diana R D

    2012-01-01

    Research supervision is a task that requires a set of abilities and skills. Many academics begin research supervision as novices and develop their abilities and skills through experience over time. We aim to provide advice about research supervision to prospective supervisors. We used critical reflection of our experiences, including feedback received from students under supervision as well as advice from the literature to develop these tips. Twelve tips are presented to assist faculty with research supervision. Research supervision is an important component of many medical academics' work. Beginning supervisors need to understand the dynamics and practicalities of supervision before they embark on this process.

  14. Social tipping points and Earth systems dynamics

    Directory of Open Access Journals (Sweden)

    R. Alexander eBentley

    2014-08-01

    Full Text Available Recently, Early Warning Signals (EWS have been developed to predict tipping points in Earth Systems. This discussion highlights the potential to apply EWS to human social and economic systems, which may also undergo similar critical transitions. Social tipping points are particularly difficult to predict, however, and the current formulation of EWS, based on a physical system analogy, may be insufficient. As an alternative set of EWS for social systems, we join with other authors encouraging a focus on heterogeneity, connectivity through social networks and individual thresholds to change.

  15. Tipping points in the dynamics of speciation.

    Science.gov (United States)

    Nosil, Patrik; Feder, Jeffrey L; Flaxman, Samuel M; Gompert, Zachariah

    2017-01-24

    Speciation can be gradual or sudden and involve few or many genetic changes. Inferring the processes generating such patterns is difficult, and may require consideration of emergent and non-linear properties of speciation, such as when small changes at tipping points have large effects on differentiation. Tipping points involve positive feedback and indirect selection stemming from associations between genomic regions, bi-stability due to effects of initial conditions and evolutionary history, and dependence on modularity of system components. These features are associated with sudden 'regime shifts' in other cellular, ecological, and societal systems. Thus, tools used to understand other complex systems could be fruitfully applied in speciation research.

  16. Tip-Based Nanofabrication for Scalable Manufacturing

    Directory of Open Access Journals (Sweden)

    Huan Hu

    2017-03-01

    Full Text Available Tip-based nanofabrication (TBN is a family of emerging nanofabrication techniques that use a nanometer scale tip to fabricate nanostructures. In this review, we first introduce the history of the TBN and the technology development. We then briefly review various TBN techniques that use different physical or chemical mechanisms to fabricate features and discuss some of the state-of-the-art techniques. Subsequently, we focus on those TBN methods that have demonstrated potential to scale up the manufacturing throughput. Finally, we discuss several research directions that are essential for making TBN a scalable nano-manufacturing technology.

  17. Windows 7 Annoyances Tips, Secrets, and Solutions

    CERN Document Server

    Karp, David

    2010-01-01

    Windows 7 may be faster and more stable than Vista, but it's a far cry from problem-free. David A. Karp comes to the rescue with the latest in his popular Windows Annoyances series. This thorough guide gives you the tools you need to fix the troublesome parts of this operating system, plus the solutions, hacks, and timesaving tips to make the most of your PC. Streamline Windows Explorer, improve the Search tool, eliminate the Green Ribbon of Death, and tame User Account Control promptsExplore powerful Registry tips and tools, and use them to customize every aspect of Windows and solve its sho

  18. Study of tip loss corrections using CFD rotor computations

    DEFF Research Database (Denmark)

    Shen, Wen Zhong; Zhu, Wei Jun; Sørensen, Jens Nørkær

    2014-01-01

    computations for wind turbines with sharp tip. Using the technique of determination of angle of attack and the CFD results for a NordTank 500 kW rotor, airfoil data are extracted and a new tip loss function on airfoil data is derived. To validate, BEM computations with the new tip loss function are carried out...... and compared with CFD results for the NordTank 500 kW turbine and the NREL 5 MW turbine. Comparisons show that BEM with the new tip loss function can predict correctly the loading near the blade tip.......Tip loss correction is known to play an important role for engineering prediction of wind turbine performance. There are two different types of tip loss corrections: tip corrections on momentum theory and tip corrections on airfoil data. In this paper, we study the latter using detailed CFD...

  19. Turbine blade squealer tip rail with fence members

    Science.gov (United States)

    Little, David A

    2012-11-20

    A turbine blade includes an airfoil, a blade tip section, a squealer tip rail, and a plurality of chordally spaced fence members. The blade tip section includes a blade tip floor located at an end of the airfoil distal from the root. The blade tip floor includes a pressure side and a suction side joined together at chordally spaced apart leading and trailing edges of the airfoil. The squealer tip rail extends radially outwardly from the blade tip floor adjacent to the suction side and extends from a first location adjacent to the airfoil trailing edge to a second location adjacent to the airfoil leading edge. The fence members are located between the airfoil leading and trailing edges and extend radially outwardly from the blade tip floor and axially from the squealer tip rail toward the pressure side.

  20. Effect of Filler and Heat Treatment on the Physical and Mechanical Properties of the Brazed Joint between Carbide Tip and Steel

    Science.gov (United States)

    Winardi, Y.; Triyono; Wijayanta, A. T.

    2017-02-01

    In this study, the effect of filler and heat treatment on the physical and mechanical properties of the brazed joint carbide tip and steel was investigated. Tip carbide YG6 and low carbon steel (SS400) is joining by torch brazing with two filler metals, silver, and copper filler. Heat treatment was performed in induction furnace. Microstructure and shear strength of the brazed joint have been investigated. Many silver filler layer are formed on the surface of the base metal rather then using copper filler. The highest shear strength is achieved using a silver filler metal at temperatur 725°C. The highest shear load is 18.62 kN.

  1. Tip-induced gating of molecular levels in carbene-based junctions

    Czech Academy of Sciences Publication Activity Database

    Foti, Giuseppe; Vázquez, Héctor

    2016-01-01

    Roč. 27, č. 12 (2016), 1-8, č. článku 125702. ISSN 0957-4484 R&D Projects: GA ČR GA15-19672S Institutional support: RVO:68378271 Keywords : single molecule transport * N-heterocyclic carbene * tip-induced gating * DFT-NEGF * metal-molecule charge rearrangement Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.440, year: 2016

  2. Internal resonance and low frequency vibration energy harvesting

    Science.gov (United States)

    Yang, Wei; Towfighian, Shahrzad

    2017-09-01

    A nonlinear vibration energy harvester with internal resonance is presented. The proposed harvester consists of two cantilevers, each with a permanent magnet on its tip. One cantilever has a piezoelectric layer at its base. When magnetic force is applied this two degrees-of-freedom nonlinear vibration system shows the internal resonance phenomenon that broadens the frequency bandwidth compared to a linear system. Three coupled partial differential equations are obtained to predict the dynamic behavior of the nonlinear energy harvester. The perturbation method of multiple scales is used to solve equations. Results from experiments done at different vibration levels with varying distances between the magnets validate the mathematical model. Experiments and simulations show the design outperforms the linear system by doubling the frequency bandwidth. Output voltage for frequency response is studied for different system parameters. The optimal load resistance is obtained for the maximum power in the internal resonance case. The results demonstrate that a design combining internal resonance and magnetic nonlinearity improves the efficiency of energy harvesting.

  3. Designing, modelling and testing of vibration energy harvester with nonlinear stiffness

    Science.gov (United States)

    Rubes, Ondrej; Hadas, Zdenek

    2017-05-01

    This paper is focused on a design of a piezoelectric vibration energy harvester with an additional nonlinear stiffness. Common piezoelectric energy harvesters consist of a cantilever with piezoceramic layers and a tip mass for tuning up the operation frequency. This system is excited by mechanical vibrations and it provides an autonomous source of electrical energy. A linear stiffness of the cantilever has very narrow resonance frequency bandwidth which makes the piezoelectric cantilever sensitive to tuning up of the resonance frequency. It could be tuned only for one narrow vibration frequency bandwidth. The piezoelectric vibration energy harvester with nonlinear stiffness could provide the resonance frequency bandwidth wider and it allows energy harvesting from the wider bandwidth of excitation vibrations. The additional nonlinear stiffness is implemented by using a set of permanent magnets. A simulation and an experiment were performed and the results show a wider resonance bandwidth. However, it depended on direction of vibration frequency sweeping. The frequency bandwidth is more than three times wider but there is only a half resonance amplitude of oscillations. That means that the maximal harvested power is lower but the average harvested power around resonance frequency was higher which was the goal of this research.

  4. A model to study the reduction of turbine blade vibration using the snubbing mechanism

    Science.gov (United States)

    Pennacchi, Paolo; Chatterton, Steven; Bachschmid, Nicolò; Pesatori, Emanuel; Turozzi, Giorgio

    2011-05-01

    Blade vibration reduction is an important task in high performance turbo machinery for power generation, in order to avoid the risk of blade failure due to the overcoming of fatigue limit. A possible way to obtain this result is a contact related phenomenon, i.e. by physically limiting the vibration amplitude on the blade tip leaving a small gap between the shrouds of adjacent blades. When the relative displacement between adjacent blades exceeds the gap, in a certain vibration mode of the blade row, a contact occurs between the shrouds, the relative motion is restricted and energy is dissipated by friction and impact during the contact. This is called the snubbing mechanism. In this paper, an original simplified model of bladed disks, in which the snubbing mechanism can occur, is presented and numerical integration in time domain furnishes the time histories of the vibrations of the blades. The level of vibration reduction is then evaluated in some different modes that could be excited for instance by the fluid flow. It is also shown that unlucky combinations of system and excitation parameters can effect also a certain magnification instead of a reduction of the vibration amplitudes. Experimental results on single blade and blade groups of a steam turbine are used to tune the parameters of the system.

  5. Detection of Rotor Forced Response Vibrations Using Stationary Pressure Transducers in a Multistage Axial Compressor

    Directory of Open Access Journals (Sweden)

    William L. Murray

    2015-01-01

    Full Text Available Blade row interactions in turbomachinery can lead to blade vibrations and even high cycle fatigue. Forced response conditions occur when a forcing function (such as impingement of stator wakes occurs at a frequency that matches the natural frequency of a blade. The objective of this research is to develop the data processing techniques needed to detect rotor blade vibration in a forced response condition from stationary fast-response pressure transducers to allow for detection of rotor vibration from transient data and lead to techniques for vibration monitoring in gas turbines. This paper marks the first time in the open literature that engine-order resonant response of an embedded bladed disk in a 3-stage intermediate-speed axial compressor was detected using stationary pressure transducers. Experiments were performed in a stage axial research compressor focusing on the embedded rotor of blisk construction. Fourier waterfall graphs from a laser tip timing system were used to detect the vibrations after applying signal processing methods to uncover these pressure waves associated with blade vibration. Individual blade response was investigated using cross covariance to compare blade passage pressure signatures through resonance. Both methods agree with NSMS data that provide a measure of the exact compressor speeds at which individual blades enter resonance.

  6. Design optimization of gold-coated fiber tips with embedded plasmonic slot nano-resonators

    Science.gov (United States)

    Petropoulou, Afroditi; Zervas, Michalis N.; Riziotis, Christos

    2017-05-01

    Nanostructures of dimensions around the operating wavelength of light can support optical resonances enhancing the incident light by orders of magnitude and concentrating it in the nanoscale. Their integration to optical fiber tips with thin metallic claddings, forming plasmonic slot nanoresonators (PSNRs), provides ease of light coupling from the fiber’s core modes to the slot and a robust platform which can find many applications in nano-optics and sensing. Guiding and modal properties of metal-coated optical fiber tips with embedded PSNRs are investigated through finite element method (FEM) simulations towards the identification of their optimization parameters. It was found that the placement of a PSNR at the cut-off radius of a metal-coated fiber tip, where the group velocity tends to zero, leads to considerable intensity enhancement of the field confined beyond the diffraction limit. Maximum intensity enhancement of optimally placed PSNRs at different radii shows a linear dependence between excitation wavelength and radius, making it feasible to engineer the proper radius for a specific wavelength for maximum enhancement.

  7. Development of a Silicon Microneedle with Three-Dimensional Sharp Tip by Electrochemical Etching

    Science.gov (United States)

    Izumi, Hayato; Okamoto, Tokusuke; Suzuki, Masato; Aoyagi, Seiji

    Aiming at the use in low-invasive medical treatments, this paper reports a fabrication technique of silicon microneedle of conical sharp point. The electrochemical etching technique is employed for sharpening the tip of a pillar, which is diced from a silicon wafer. A finely smooth tip surface is obtained due to electrochemical etching reactions, and is effective for easy insertion. The fabrication method is based on inexpensive wet etching, which does not require expensive fabrication facilities such as deep reactive ion etching (DRIE). A sharp needle was successfully fabricated, the tip angle of which was considerably small and was distributed within the range from 15 to 30 deg. An experiment of inserting the fabricated needle into an artificial skin of silicone rubber was carried out. As the results, the resistance force during insertion was much reduced compared to those of two-dimensional sharp needles. Imitating mosquito's motion, the effectiveness of applying vibration to the fabricated needle during insertion was also confirmed. After biocompatible Parylene coating, puncturing a human skin was demonstrated assuming a lancet usage for the diabetics, in which the bleeding was surely observed.

  8. Vibration and Operational Characteristics of a Composite-Steel (Hybrid) Gear

    Science.gov (United States)

    Handschuh, Robert F.; LaBerge, Kelsen E.; DeLuca, Samuel; Pelagalli, Ryan

    2014-01-01

    Hybrid gears have been tested consisting of metallic gear teeth and shafting connected by composite web. Both free vibration and dynamic operation tests were completed at the NASA Glenn Spur Gear Fatigue Test Facility, comparing these hybrid gears to their steel counterparts. The free vibration tests indicated that the natural frequency of the hybrid gear was approximately 800 Hz lower than the steel test gear. The dynamic vibration tests were conducted at five different rotational speeds and three levels of torque in a four square test configuration. The hybrid gears were tested both as fabricated (machined, composite layup, then composite cure) and after regrinding the gear teeth to the required aerospace tolerance. The dynamic vibration tests indicated that the level of vibration for either type of gearing was sensitive to the level of load and rotational speed.

  9. Tuned liquid column dampers for mitigation of edgewise vibrations in rotating wind turbine blades

    DEFF Research Database (Denmark)

    Zhang, Zili; Basu, Biswajit; Nielsen, Søren R.K.

    2015-01-01

    Edgewise vibrations in wind turbine blades are lightly damped, and large amplitude vibrations induced by the turbulence may significantly shorten the fatigue life of the blade. This paper investigates the performance of tuned liquid column dampers (TLCDs) for mitigating edgewise vibrations...... are the mounting position, the mass ratio, the geometries, and the head loss coefficient of the damper. Based on a reduced 2-DOF nonlinear model developed by the authors, the optimization of these parameters are carried out by minimizing the standard deviation of the edgewise tip displacement...... and the aerodynamic damping presented in different modes. Various turbulence intensities and rotational speeds of the rotor have been considered to evaluate the performance of the TLCD. Further, the optimized damper is incorporated into the 13-DOF model to verify the application of the decoupled optimization...

  10. Vibration response of misaligned rotors

    Science.gov (United States)

    Patel, Tejas H.; Darpe, Ashish K.

    2009-08-01

    Misalignment is one of the common faults observed in rotors. Effect of misalignment on vibration response of coupled rotors is investigated in the present study. The coupled rotor system is modelled using Timoshenko beam elements with all six dof. An experimental approach is proposed for the first time for determination of magnitude and harmonic nature of the misalignment excitation. Misalignment effect at coupling location of rotor FE model is simulated using nodal force vector. The force vector is found using misalignment coupling stiffness matrix, derived from experimental data and applied misalignment between the two rotors. Steady-state vibration response is studied for sub-critical speeds. Effect of the types of misalignment (parallel and angular) on the vibration behaviour of the coupled rotor is examined. Along with lateral vibrations, axial and torsional vibrations are also investigated and nature of the vibration response is also examined. It has been found that the misalignment couples vibrations in bending, longitudinal and torsional modes. Some diagnostic features in the fast Fourier transform (FFT) of torsional and longitudinal response related to parallel and angular misalignment have been revealed. Full spectra and orbit plots are effectively used to reveal the unique nature of misalignment fault leading to reliable misalignment diagnostic information, not clearly brought out by earlier studies.

  11. Barbecue Basics: Tips to Prevent Foodborne Illness

    Medline Plus

    Full Text Available ... For Consumers Home For Consumers Consumer Updates Barbecue Basics: Tips to Prevent Foodborne Illness Share Tweet Linkedin ... and 140°F, so summer heat makes the basics of food safety especially important. “Fortunately, there are ...

  12. The Tipping Points of Technology Development

    Directory of Open Access Journals (Sweden)

    Tauno Kekäle

    2014-07-01

    Full Text Available The tipping point, the decisive point in time in the competition between old and new, is an interesting phenomenon in physics of today. This aspect in technology acceptance is connected to many business decisions such as technology investments, product releases, resource allocation, sales forecasts and, ultimately, affects the profitability and even survival of a company. The tipping point itself is based on many stochastic and dynamic variables, and the process may at least partly be described as path-dependent. This paper analyses the tipping point from three aspects: (1 product performance, (2 features of the market and infrastructure (including related technologies and human network externalities, and (3 actions of the incumbents (including customer lock-in, systems lock-in, and sustaining innovation. The paper is based on the Bass s-curve idea and the technology trajectory concept proposed by Dosi. Three illustrative cases are presented to make the point of the multiple factors affecting technology acceptance and, thus, the tipping point. The paper also suggests outlines for further research in field of computer simulation.

  13. What Do You Mean, 'Tipping Point'?

    NARCIS (Netherlands)

    Nes, van E.H.; Shojaei Arani, M.; Staal, A.; Bolt, van der B.; Flores, Bernardo M.; Bathiany, S.; Scheffer, M.

    2016-01-01

    Over the past 10 years the use of the term ‘tipping point’ in the scientific literature has exploded. It was originally used loosely as a metaphor for the phenomenon that, beyond a certain threshold, runaway change propels a system to a new state. Although several specific mathematical definitions

  14. Tips: Improving Acoustics for Music Teaching.

    Science.gov (United States)

    Geerdes, Harold P.

    A specifications pamphlet offers methods, ideas, and suggestions on how music educators can upgrade their existing music facilities or design new ones correctly. Guidelines address room acoustic fundamentals, how to critique a music room, hints on upgrading acoustic weaknesses, and general tips to follow when trying to maximize acoustics when…

  15. Microtubules guide root hair tip growth

    NARCIS (Netherlands)

    Sieberer, B.; Ketelaar, M.J.; Esseling, J.J.; Emons, A.M.C.

    2005-01-01

    The ability to establish cell polarity is crucial to form and function of an individual cell. Polarity underlies critical processes during cell development, such as cell growth, cell division, cell differentiation and cell signalling. Interphase cytoplasmic microtubules in tip-growing fission yeast

  16. Social Media Tips to Enhance Medical Education.

    Science.gov (United States)

    Shah, Vikas; Kotsenas, Amy L

    2017-06-01

    In this article, we describe how social media can supplement traditional education, articulate the advantages and disadvantages of various social media platforms for both teachers and learners, discuss best practices to maintain confidentiality of protected health information, and provide tips for implementing social media-based teaching into the training curriculum. Copyright © 2017 The Association of University Radiologists. All rights reserved.

  17. Technology Tips and Tricks for Music Educators

    Science.gov (United States)

    Peterson, Hal

    2006-01-01

    This article presents technology tips and ideas for music educators. To keep current with music technology, you will need to spend time with it regularly, just like you would practice a musical instrument or voice. Basic office software programs can help you with administrative tasks and duties. Your computers are important tools for your program,…

  18. Adipogenesis: forces that tip the scales

    DEFF Research Database (Denmark)

    MacDougald, Ormond A; Mandrup, Susanne

    2001-01-01

    factors reviewed include Wnt, transforming growth factor beta, inflammatory cytokines and prostaglandin F(2alpha). Tipping the scales towards or away from adipogenesis has profound implications for human health. In this review, we describe recent contributions to the field and will focus on factors...

  19. Video Tips for Worry-Free Presentations

    Science.gov (United States)

    Berendsen, M.; Santascoy, J.

    2011-09-01

    Amateur astronomers and other volunteer informal science educators express concerns when talking with the public since they often lack specific training in public speaking. The Astronomical Society of the Pacific has developed a series of videos and supporting materials to provide tips and exercises for practicing the skills associated with the most commonly expressed concerns.

  20. Nanobits - exchangable and customisable scanning probe tips

    DEFF Research Database (Denmark)

    Yildiz, Izzet

    Invention of atomic force microscopy (AFM) pioneered a novel aspect for the surface metrology concept. A range of scanning probe methods have been developed over the years based on different sorts of tip-surface interaction: electrical, optical, thermal, force. Reproducible and fast fabrication...

  1. Fast Food: Tips for Choosing Healthier Options

    Science.gov (United States)

    ... what you order. Consider these tips. If the fast-food restaurant offers several sandwich sizes, pick the smallest. Bypass hamburgers with two or three beef patties, which can be close to 800 calories. Choose instead a regular- or children's-sized hamburger, which has about 250 calories. And ...

  2. Tip cells: master regulators of tubulogenesis?

    Science.gov (United States)

    Weavers, Helen; Skaer, Helen

    2014-07-01

    The normal development of an organ depends on the coordinated regulation of multiple cell activities. Focusing on tubulogenesis, we review the role of specialised cells or groups of cells that are selected from within tissue primordia and differentiate at the outgrowing tips or leading edge of developing tubules. Tip or leading cells develop distinctive patterns of gene expression that enable them to act both as sensors and transmitters of intercellular signalling. This enables them to explore the environment, respond to both tissue intrinsic signals and extrinsic cues from surrounding tissues and to regulate the behaviour of their neighbours, including the setting of cell fate, patterning cell division, inducing polarity and promoting cell movement and cell rearrangements by neighbour exchange. Tip cells are also able to transmit mechanical tension to promote tissue remodelling and, by interacting with the extracellular matrix, they can dictate migratory pathways and organ shape. Where separate tubular structures fuse to form networks, as in the airways of insects or the vascular system of vertebrates, specialised fusion tip cells act to interconnect disparate elements of the developing network. Finally, we consider their importance in the maturation of mature physiological function and in the development of disease. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

  3. Tip-enhanced bulk photovoltaic effect

    Science.gov (United States)

    Sturman, B.; Podivilov, E.

    2017-10-01

    Using the conventional macroscopic description of the bulk photovoltaic effect we analyze the light-induced currents and electric fields arising in the optical configuration with a continuous bottom electrode and a small circular top electrode. This scheme is relevant to recent experiments on the tip-enhanced photovoltaic effect in ferroelectrics. It is shown that a light-induced electric field remains nonzero inside the sample even in the short-circuit regime. Moreover, it is enhanced compared to the photovoltaic field in a large area and strongly enhanced near the top electrode. A field-assisted collection of charge carriers from the illuminated area produces a strong local enhancement of the current density near the top electrode. The tip-enhanced electric field is typically parallel to the photovoltaic current. It is sufficient to repolarize the crystal near the top electrode. The effect of the tip enhancement on the light-current transformation efficiency is considered, and predictions for the tip radius and sample thickness dependencies of the total light-induced current are made.

  4. Tips for Older Dietary Supplement Users

    Science.gov (United States)

    ... Administration, DHHS, Center for Food Safety and Applied Nutrition: Dietary Supplements Tips for the Savvy Supplement User: Making Informed ... that supplements include botanical/herbal as well as vitamin/mineral ... may see sold as dietary supplements. It is not possible to list them all ...

  5. Tips for Building a Classroom Library.

    Science.gov (United States)

    Schleper, David R.

    1991-01-01

    Eleven tips to teachers of hearing-impaired students wanting to build a classroom library include seeking community donations; joining book clubs; borrowing from the school library; involving the parent/teacher association; calling on the deaf community; contacting local service organizations; and asking for discounts. (DB)

  6. Tips for Healthy Children and Families

    Science.gov (United States)

    ... will help you make smart choices for your family. Children imitate their parents, so it’s important to set a good example. The tips below can help your family be healthy and happy.Path to improved healthEating better (for children and families)Start the day with a healthy ...

  7. Have Diabetes? Get Tips for Safe Travels

    Science.gov (United States)

    ... this? Submit Button Past Emails Have Diabetes? Get Tips for Safe Travels Language: English (US) Español (Spanish) ... file Microsoft PowerPoint file Microsoft Word file Microsoft Excel file Audio/Video file Apple Quicktime file RealPlayer ...

  8. Barbecue Basics: Tips to Prevent Foodborne Illness

    Medline Plus

    Full Text Available ... Español Search FDA Submit search Popular Content Home Food Drugs Medical Devices Radiation-Emitting Products Vaccines, ... Biologics Animal & Veterinary Cosmetics Tobacco Products For Consumers Home For Consumers Consumer Updates Barbecue Basics: Tips to ...

  9. A refined tip correction based on decambering

    DEFF Research Database (Denmark)

    Sørensen, Jens Nørkær; Dag, Kaya Onur; Ramos García, Néstor

    2016-01-01

    A new tip correction for use in performance codes based on the blade element momentum (BEM) or the lifting-line techniqueis presented. The correction modifies the circulation by taking into account the additional influence of the inductionof the vortices in the wake, using the so-called decamberi...

  10. Take a Tip from the Cubs

    Science.gov (United States)

    Fornaciari, James

    2016-01-01

    As legendary Cubs manager Joe Maddon did with his players, seeing students as people first works for teachers who hope to build cohesive classes that achieve. Maddon's strength was his emphasis on cultivating positive relationships among his players. Taking a tip from Maddon's strategy, Fornaciari, an Advanced Placement history teacher, shares…

  11. Barbecue Basics: Tips to Prevent Foodborne Illness

    Medline Plus

    Full Text Available ... health and wellness tips, and the latest safety info on FDA-regulated products and public health issues. ... Hampshire Avenue Silver Spring, MD 20993 1-888-INFO-FDA (1-888-463-6332) Contact FDA Subscribe ...

  12. Copyright Tips for Editors and Publishers.

    Science.gov (United States)

    Polansky, Barbara Friedman

    1985-01-01

    Expands on three main copyright tips as they apply to editors and publishers: (1) know copyright basics (copyright notice, copyright registration, fair use); (2) know whom to contact if you have copyright questions or if you need to obtain copyright permission; and (3) communicate questions, intentions, and policies clearly and fully. (EJS)

  13. Tips to Making Successful School Board Presentations

    Science.gov (United States)

    Cheasty, Michelle

    2011-01-01

    Over the years, the author has had the opportunity to make several presentations to school boards. The author offers some tips and tricks she has learned, having given board presentations about the specific topics she listed in this article, and receiving feedback after each presentation. She points out that the most important thing to keep in…

  14. Tips for Teaching Textiles and Clothing.

    Science.gov (United States)

    New York State Education Dept., Albany. Bureau of Continuing Education Curriculum Development.

    This guide was prepared to help instructors of adult textiles and clothing programs improve their teaching; it is designed to be used with other department publications: Clothing Services Training Guide, Resource Courses for Planning Local Adult Homemaking Programs, and Resource Kit Tips for Teaching Textiles and Clothing (see AC 008 741). Each…

  15. Final Technical Report: Electrohydrodynamic Tip Streaming

    Energy Technology Data Exchange (ETDEWEB)

    Basaran, Osman [Purdue Univ., West Lafayette, IN (United States)

    2016-01-06

    When subjected to strong electric fields, liquid drops and films form conical tips and emit thin jets from their tips. Such electrodydrodynamic (EDH) tip streaming or cone-jetting phenomena, which are sometimes referred to as electrospraying, occur widely in nature, e.g., in ejection of streams of small charged drops from pointed tips of raindrops in thunderclouds, and technology, e.g., in electrospray mass spectrometry or electric field-driven solvent extraction. More recently, EHD cone-jetting has emerged as a powerful technique for direct printing of solar cells, micro- and nano- particle production, and microencapsulation for controlled release. In many of the aforementioned situations, of equal importance to the processes by which one drop disintegrates to form several drops are those by which (a) two drops come together and coalesce and (b) two drops are coupled to form a double droplet system (DDS) or a capillary switch (CS). the main objective of this research program is to advance through simulation, theory, and experiment the breakup, coalescence, and oscillatory dynamics of single and pairs of charged as well as uncharged drops.

  16. Tissue vibration in prolonged running.

    Science.gov (United States)

    Friesenbichler, Bernd; Stirling, Lisa M; Federolf, Peter; Nigg, Benno M

    2011-01-04

    The impact force in heel-toe running initiates vibrations of soft-tissue compartments of the leg that are heavily dampened by muscle activity. This study investigated if the damping and frequency of these soft-tissue vibrations are affected by fatigue, which was categorized by the time into an exhaustive exercise. The hypotheses were tested that (H1) the vibration intensity of the triceps surae increases with increasing fatigue and (H2) the vibration frequency of the triceps surae decreases with increasing fatigue. Tissue vibrations of the triceps surae were measured with tri-axial accelerometers in 10 subjects during a run towards exhaustion. The frequency content was quantified with power spectra and wavelet analysis. Maxima of local vibration intensities were compared between the non-fatigued and fatigued states of all subjects. In axial (i.e. parallel to the tibia) and medio-lateral direction, most local maxima increased with fatigue (supporting the first hypothesis). In anterior-posterior direction no systematic changes were found. Vibration frequency was minimally affected by fatigue and frequency changes did not occur systematically, which requires the rejection of the second hypothesis. Relative to heel-strike, the maximum vibration intensity occurred significantly later in the fatigued condition in all three directions. With fatigue, the soft tissue of the triceps surae oscillated for an extended duration at increased vibration magnitudes, possibly due to the effects of fatigue on type II muscle fibers. Thus, the protective mechanism of muscle tuning seems to be reduced in a fatigued muscle and the risk of potential harm to the tissue may increase. Copyright © 2010 Elsevier Ltd. All rights reserved.

  17. Finite element based model predictive control for active vibration suppression of a one-link flexible manipulator.

    Science.gov (United States)

    Dubay, Rickey; Hassan, Marwan; Li, Chunying; Charest, Meaghan

    2014-09-01

    This paper presents a unique approach for active vibration control of a one-link flexible manipulator. The method combines a finite element model of the manipulator and an advanced model predictive controller to suppress vibration at its tip. This hybrid methodology improves significantly over the standard application of a predictive controller for vibration control. The finite element model used in place of standard modelling in the control algorithm provides a more accurate prediction of dynamic behavior, resulting in enhanced control. Closed loop control experiments were performed using the flexible manipulator, instrumented with strain gauges and piezoelectric actuators. In all instances, experimental and simulation results demonstrate that the finite element based predictive controller provides improved active vibration suppression in comparison with using a standard predictive control strategy. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.

  18. Photochromism of Composite Organometallic Nanostructures Based on Diarylethenes. II. Vibrational Spectroscopy and Quantum Chemistry Studies

    Science.gov (United States)

    Vasilyuk, G. T.; Askirka, V. F.; Lavysh, A. V.; Kurguzenkov, S. A.; Yasinskii, V. M.; Kobeleva, O. I.; Valova, T. M.; Ayt, A. O.; Barachevsky, V. A.; Yarovenko, V. N.; Krayushkin, M. M.; Maskevich, S. A.

    2017-11-01

    The structure and photochromic transformations of nanostructured organometallic composites consisting of Ag nanoparticles with shells of photochromic diarylethenes (DAEs) deposited from various solutions onto the nanoparticles were studied using infrared absorption and surface enhanced Raman scattering (SERS) vibrational spectroscopy and quantum chemistry. The studied nanostructures exhibited photochromic properties manifested as reversible photoinduced changes of the relative intensities of SERS bands related to vibrations of bonds participating in the reversible photoisomerization. Spectral manifestations of chemical interaction between metal nanoparticles and DAE molecules were detected.

  19. Molecular vibrations the theory of infrared and Raman vibrational spectra

    CERN Document Server

    Wilson, E Bright; Cross, Paul C

    1980-01-01

    Pedagogical classic and essential reference focuses on mathematics of detailed vibrational analyses of polyatomic molecules, advancing from application of wave mechanics to potential functions and methods of solving secular determinant.

  20. Avoid heat transfer equipment vibration

    Energy Technology Data Exchange (ETDEWEB)

    Ganapathy, V.

    1987-06-01

    Tube bundles in heat exchangers, boilers, superheaters and heaters are often subject to vibration and noise problems. Vibration can lead to tube thinning and wear, resulting in tube failures. Excessive noise can be a problem to plant operating personnel. Large gas pressure drop across the equipment is also a side effect, which results in large operating costs. With the design checks presented in this paper, one can predict during design if problems associated with noise and vibration are likely to occur in petroleum refineries.

  1. Tipping news in information accumulation system

    Science.gov (United States)

    Shin, J. K.

    2010-05-01

    As a continuous opinion dynamics model, the information accumulation system (IAS) includes three basic mechanisms of the news, the inheritance and the diffusion as contributing to the information accumulation process of a system. A system is composed of agents who diffuse information through internal interaction, while each of them has incomplete memory or inheritance rate. The news comes from external sources of information, such as mass media. Previously the model IAS was studied only for the small news problems. In this study, a tipping news problem is considered. A key question of the problem is: what is the minimum strength of advertisement that can tip the minority opinion to a majority one? Dynamics of the IAS is briefly revisited with a special interest on nonlinear behavior of the model. In particular, it is shown that a discrete map of the IAS for a single color problem can be transformed into a logistic map, from which the dynamics of the IAS can be better understood. To show the applicability of the IAS model, the result is applied to explain the concept of the critical population size, which claims that there is a minimum population size for a social knowledge system to be continuously inherited without being lost. And critical size of the tipping news is found analytically in terms of IAS parameters. Some of the key results from the present study are compared in detail with the results from the Brownian particle model, which is believed to be the most similar model to the IAS. The concept of tipping news is used to show that a traditional society can tip at an exceptionally low inter-community exposure. Finally, the result was applied to the language competition problem.

  2. 14 CFR 33.63 - Vibration.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Vibration. 33.63 Section 33.63 Aeronautics... STANDARDS: AIRCRAFT ENGINES Design and Construction; Turbine Aircraft Engines § 33.63 Vibration. Each engine... because of vibration and without imparting excessive vibration forces to the aircraft structure. ...

  3. 14 CFR 33.83 - Vibration test.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Vibration test. 33.83 Section 33.83... STANDARDS: AIRCRAFT ENGINES Block Tests; Turbine Aircraft Engines § 33.83 Vibration test. (a) Each engine must undergo vibration surveys to establish that the vibration characteristics of those components that...

  4. 14 CFR 33.33 - Vibration.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Vibration. 33.33 Section 33.33 Aeronautics... STANDARDS: AIRCRAFT ENGINES Design and Construction; Reciprocating Aircraft Engines § 33.33 Vibration. The... vibration and without imparting excessive vibration forces to the aircraft structure. ...

  5. 14 CFR 33.43 - Vibration test.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Vibration test. 33.43 Section 33.43... STANDARDS: AIRCRAFT ENGINES Block Tests; Reciprocating Aircraft Engines § 33.43 Vibration test. (a) Each engine must undergo a vibration survey to establish the torsional and bending vibration characteristics...

  6. 49 CFR 178.819 - Vibration test.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Vibration test. 178.819 Section 178.819... Testing of IBCs § 178.819 Vibration test. (a) General. The vibration test must be conducted for the... vibration test. (b) Test method. (1) A sample IBC, selected at random, must be filled and closed as for...

  7. Rectangular Parallelepiped Vibration in Plane Strain State

    OpenAIRE

    Hanckowiak, Jerzy

    2004-01-01

    In this paper we present a vibration spectrum of a homogenous parallelepiped (HP) under the action of volume and surface forces resulting from the exponent displacements entering the Fourier transforms. Vibration under the action of axial surface tractions and the free vibration are described separately. A relationship between the high frequency vibration and boundary conditions (BC) is also considered.

  8. Vibrational and theoretical study of selected diacetylenes.

    Science.gov (United States)

    Roman, Maciej; Baranska, Malgorzata

    2013-11-01

    Six commonly used disubstituted diacetylenes with short side-chains (RCCCCR, where R=CH2OH, CH2OPh, C(CH3)2OH, C(CH3)3, Si(CH3)3, and Ph) were analyzed using vibrational spectroscopy and quantum-chemical calculations to shed new light on structural and spectroscopic properties of these compounds. Prior to that the conformational analysis of diacetylenes was performed to search the Potential Energy Surface for low-energy minima. Theoretical investigations were followed by the potential energy distribution (PED) analysis to gain deeper insight into FT-Raman and FT-IR spectra that, in some cases, were recorded for the first time for the studied compounds. The analysis was focused mainly on spectral features of the diacetylene system sensitive to the substitution. Shifts of the characteristic bands and changes in bond lengths were observed when changing the substituent. Furthermore, Fermi resonance was observed in the vibrational spectra of some diacetylenes. FT-IR spectra were measured by using two methods, i.e. transmission (with KBr substrate) and Attenuated Total Reflection (ATR), showing the latter adequate and fast tool for IR measurements of diacetylenes. Additionally, Surface Enhanced Raman Spectroscopy (SERS) was applied for phenyl derivative for the first time to study its interaction with metallic nanoparticles that seems to be perpendicular. Copyright © 2013 Elsevier B.V. All rights reserved.

  9. DYNAMIC MODELLING OF VIBRATIONS ASSISTED DRILLING

    Directory of Open Access Journals (Sweden)

    Mathieu LADONNE

    2015-05-01

    Full Text Available The number of multi-materials staking configurations for aeronautical structures is increasing, with the evolution of composite and metallic materials. For drilling the fastening holes, the processes of Vibration Assisted Drilling (VAD expand rapidly, as it permits to improve reliability of drilling operations on multilayer structures. Among these processes of VAD, the solution with forced vibrations added to conventional feed to create a discontinuous cutting is the more developed in industry. The back and forth movement allows to improve the evacuation of chips by breaking it. This technology introduces two new operating parameters, the frequency and the amplitude of the oscillation. To optimize the process, the choice of those parameters requires first to model precisely the operation cutting and dynamics. In this paper, a kinematic modelling of the process is firstly proposed. The limits of the model are analysed through comparison between simulations and measurements. The proposed model is used to develop a cutting force model that allows foreseeing the operating conditions which ensure good chips breaking and tool life improvement.

  10. Menopause: Treatment Tips From the National Institute on Aging

    Science.gov (United States)

    ... Menopause Treatment Tips From the National Institute on Aging Past Issues / Winter 2017 Table of Contents Possible ... Menopause / Treatment Tips From the National Institute on Aging / Menopause Mayhem / Weighing Your Treatment Options Winter 2017 ...

  11. Essential Tremor (ET): Coping Tips for Everyday Living

    Science.gov (United States)

    ... Options Donate Prev Next IETF > Coping with Essential Tremor > Coping Tips for Everyday Living Coping Tips for ... that can lead to stress with temporarily worsening tremor. In order to assist people who have ET ...

  12. Early-warning indicators for rate-induced tipping.

    Science.gov (United States)

    Ritchie, Paul; Sieber, Jan

    2016-09-01

    A dynamical system is said to undergo rate-induced tipping when it fails to track its quasi-equilibrium state due to an above-critical-rate change of system parameters. We study a prototypical model for rate-induced tipping, the saddle-node normal form subject to time-varying equilibrium drift and noise. We find that both most commonly used early-warning indicators, increase in variance and increase in autocorrelation, occur not when the equilibrium drift is fastest but with a delay. We explain this delay by demonstrating that the most likely trajectory for tipping also crosses the tipping threshold with a delay, and therefore, the tipping itself is delayed. We find solutions of the variational problem determining the most likely tipping path using numerical continuation techniques. The result is a systematic study of the most likely tipping time in the plane of two parameters, distance from tipping threshold and noise intensity.

  13. Tips for Good Health in Later Life: For Older Women

    Science.gov (United States)

    ... Geriatrics Osteoporosis Prevention Related Documents PDF Tips for Good Health in Later Life: For Older Women Download Join our e-newsletter! Resources Tips for Good Health in Later Life: For Older Women Tools and ...

  14. Restaurant Dining: Seven Tips for Staying Gluten Free

    Science.gov (United States)

    ... Education Bulletin Restaurant Dining: Seven Tips for Staying Gluten-Free Updated May 2014 Tips for Dining Away ... 1. Selection of eating establishment. • Your success at gluten-free dining will be determined by a number ...

  15. Tips to Help Children through Their Medical Tests

    Science.gov (United States)

    ... Acidosis and Alkalosis Adrenal Insufficiency and Addison Disease Alcoholism Allergies Alzheimer Disease Anemia Angina Ankylosing Spondylitis Anthrax ... Tips on Blood Testing Tips to Help the Elderly through Their Medical Tests Elsewhere On The Web ...

  16. Cytology of root tips of Dioscoreophyllum cumminsii (STAPF) diel ...

    African Journals Online (AJOL)

    , University of Nigeria Nsukka. Root tips for the chromosome work were obtained from three sources: runners originating from main vine; sprouting pieces of tubers and redifferentiated root tips from callus. The results showed that normal ...

  17. In-situ Studies of the Reactions of Bifunctional and Heterocyclic Molecules over Noble Metal Single Crystal and Nanoparticle Catalysts Studied with Kinetics and Sum-Frequency Generation Vibrational Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Kliewer, Christopher J. [Univ. of California, Berkeley, CA (United States)

    2009-06-30

    Sum frequency generation surface vibrational spectroscopy (SFG-VS) in combination with gas chromatography (GC) was used in-situ to monitor surface bound reaction intermediates and reaction selectivities for the hydrogenation reactions of pyrrole, furan, pyridine, acrolein, crotonaldehyde, and prenal over Pt(111), Pt(100), Rh(111), and platinum nanoparticles under Torr reactant pressures and temperatures of 300K to 450K. The focus of this work is the correlation between the SFG-VS observed surface bound reaction intermediates and adsorption modes with the reaction selectivity, and how this is affected by catalyst structure and temperature. Pyrrole hydrogenation was investigated over Pt(111) and Rh(111) single crystals at Torr pressures. It was found that pyrrole adsorbs to Pt(111) perpendicularly by cleaving the N-H bond and binding through the nitrogen. However, over Rh(111) pyrrole adsorbs in a tilted geometry binding through the {pi}-aromatic orbitals. A surface-bound pyrroline reaction intermediate was detected over both surfaces with SFG-VS. It was found that the ring-cracking product butylamine is a reaction poison over both surfaces studied. Furan hydrogenation was studied over Pt(111), Pt(100), 10 nm cubic platinum nanoparticles and 1 nm platinum nanoparticles. The product distribution was observed to be highly structure sensitive and the acquired SFG-VS spectra reflected this sensitivity. Pt(100) exhibited more ring-cracking to form butanol than Pt(111), while the nanoparticles yielded higher selectivities for the partially saturated ring dihydrofuran. Pyridine hydrogenation was investigated over Pt(111) and Pt(100). The α-pyridyl surface adsorption mode was observed with SFG-VS over both surfaces. 1,4-dihydropyridine was seen as a surface intermediate over Pt(100) but not Pt(111). Upon heating the surfaces to 350K, the adsorbed pyridine changes to a flat-lying adsorption mode. No evidence was found for the pyridinium cation. The hydrogenation of the

  18. 23 CFR 450.330 - Project selection from the TIP.

    Science.gov (United States)

    2010-04-01

    ... 23 Highways 1 2010-04-01 2010-04-01 false Project selection from the TIP. 450.330 Section 450.330... from the TIP. (a) Once a TIP that meets the requirements of 23 U.S.C. 134(j), 49 U.S.C. 5303(j), and § 450.324 has been developed and approved, the first year of the TIP shall constitute an “agreed to...

  19. 26 CFR 31.3401(a)(16)-1 - Tips.

    Science.gov (United States)

    2010-04-01

    ... 26 Internal Revenue 15 2010-04-01 2010-04-01 false Tips. 31.3401(a)(16)-1 Section 31.3401(a)(16)-1... Income Tax at Source § 31.3401(a)(16)-1 Tips. Tips paid to an employee are excepted from wages and hence not subject to withholding if— (a) The tips are paid in any medium other than cash, or (b) The cash...

  20. The Effects of Service Quality on Customers’ Tipping Behavior

    OpenAIRE

    Murat Yesiltas; Ozcan Zorlu; Serhat Adem Sop; Elif Tuba Beydilli

    2014-01-01

    In recent years, customer tipping behaviors have become one of the most debated issues in the context of tourist behaviors and social norms. And the numerous studies have begun to focus on searching the main determiners of tipping. Although some determiners of tipping such as diner habits, stereotypes, service atmosphere, server’s actions, and bill size intensively are being searched, service quality as a determiner of tipping is still one of the most researched topics among others. However, ...