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Sample records for modeling thin wires

  1. Highly stretchable wrinkled gold thin film wires

    Science.gov (United States)

    Kim, Joshua; Park, Sun-Jun; Nguyen, Thao; Chu, Michael; Pegan, Jonathan D.; Khine, Michelle

    2016-02-01

    With the growing prominence of wearable electronic technology, there is a need to improve the mechanical reliability of electronics for more demanding applications. Conductive wires represent a vital component present in all electronics. Unlike traditional planar and rigid electronics, these new wearable electrical components must conform to curvilinear surfaces, stretch with the body, and remain unobtrusive and low profile. In this paper, the piezoresistive response of shrink induced wrinkled gold thin films under strain demonstrates robust conductive performance in excess of 200% strain. Importantly, the wrinkled metallic thin films displayed negligible change in resistance of up to 100% strain. The wrinkled metallic wires exhibited consistent performance after repetitive strain. Importantly, these wrinkled thin films are inexpensive to fabricate and are compatible with roll to roll manufacturing processes. We propose that these wrinkled metal thin film wires are an attractive alternative to conventional wires for wearable applications.

  2. Highly stretchable wrinkled gold thin film wires

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Joshua, E-mail: joshuk7@uci.edu; Park, Sun-Jun; Nguyen, Thao [Department of Chemical Engineering and Materials Science, University of California, Irvine, California 92697 (United States); Chu, Michael [Department of Biomedical Engineering, University of California, Irvine, California 92697 (United States); Pegan, Jonathan D. [Department of Materials and Manufacturing Technology, University of California, Irvine, California 92697 (United States); Khine, Michelle, E-mail: mkhine@uci.edu [Department of Chemical Engineering and Materials Science, University of California, Irvine, California 92697 (United States); Department of Biomedical Engineering, University of California, Irvine, California 92697 (United States)

    2016-02-08

    With the growing prominence of wearable electronic technology, there is a need to improve the mechanical reliability of electronics for more demanding applications. Conductive wires represent a vital component present in all electronics. Unlike traditional planar and rigid electronics, these new wearable electrical components must conform to curvilinear surfaces, stretch with the body, and remain unobtrusive and low profile. In this paper, the piezoresistive response of shrink induced wrinkled gold thin films under strain demonstrates robust conductive performance in excess of 200% strain. Importantly, the wrinkled metallic thin films displayed negligible change in resistance of up to 100% strain. The wrinkled metallic wires exhibited consistent performance after repetitive strain. Importantly, these wrinkled thin films are inexpensive to fabricate and are compatible with roll to roll manufacturing processes. We propose that these wrinkled metal thin film wires are an attractive alternative to conventional wires for wearable applications.

  3. Welding Wires To Thin Thermocouple Films

    Science.gov (United States)

    Holanda, Raymond; Kim, Walter S.; Danzey, Gerald A.; Pencil, Eric; Wadel, Mary

    1993-01-01

    Parallel-gap resistance welding yields joints surviving temperatures of about 1,000 degrees C. Much faster than thermocompression bonding. Also exceeds conductive-paste bonding and sputtering thin films through porous flame-sprayed insulation on prewelded lead wires. Introduces no foreign material into thermocouple circuit and does not require careful control of thickness of flame-sprayed material.

  4. Thin Magnetically Soft Wires for Magnetic Microsensors

    Directory of Open Access Journals (Sweden)

    Arcady Zhukov

    2009-11-01

    Full Text Available Recent advances in technology involving magnetic materials require development of novel advanced magnetic materials with improved magnetic and magneto-transport properties and with reduced dimensionality. Therefore magnetic materials with outstanding magnetic characteristics and reduced dimensionality have recently gained much attention. Among these magnetic materials a family of thin wires with reduced geometrical dimensions (of order of 1–30 μm in diameter have gained importance within the last few years. These thin wires combine excellent soft magnetic properties (with coercivities up to 4 A/m with attractive magneto-transport properties (Giant Magneto-impedance effect, GMI, Giant Magneto-resistance effect, GMR and an unusual re-magnetization process in positive magnetostriction compositions exhibiting quite fast domain wall propagation. In this paper we overview the magnetic and magneto-transport properties of these microwires that make them suitable for microsensor applications.

  5. Photonic band gap in thin wire metamaterials.

    Science.gov (United States)

    Hock, Kai Meng

    2008-03-01

    We investigate the band structure of a class of photonic crystals made from only thin wires. Using a different method, we demonstrate that a complete photonic band gap is possible for such materials. Band gap materials normally consist of space filling dielectric or metal, whereas thin wires occupy a very small fraction of the volume. We show that this is related to the large increase in scattering at the Brillouin zone boundary. The method we developed brings together the calculation techniques in three different fields. The first is the calculation of scattering from periodic, tilted antennas, which we improve upon. The second is the standard technique for frequency selective surface design. The third is obtained directly from low energy electron diffraction theory. Good agreements with experiments for left handed materials, negative materials, and frequency selective surfaces are demonstrated.

  6. Modelling the torsion of thin metal wires by distortion gradient plasticity

    Science.gov (United States)

    Bardella, Lorenzo; Panteghini, Andrea

    2015-05-01

    Under small strains and rotations, we apply a phenomenological higher-order theory of distortion gradient plasticity to the torsion problem, here assumed as a paradigmatic benchmark of small-scale plasticity. Peculiar of the studied theory, proposed about ten years ago by Morton E. Gurtin, is the constitutive inclusion of the plastic spin, affecting both the free energy and the dissipation. In particular, the part of the free energy, called the defect energy, which accounts for Geometrically Necessary Dislocations, is a function of Nye's dislocation density tensor, dependent on the plastic distortion, including the plastic spin. For the specific torsion problem, we implement this distortion gradient plasticity theory into a Finite Element (FE) code characterised by implicit (Backward Euler) time integration, numerically robust and accurate for both viscoplastic and rate-independent material responses. We show that, contrariwise to other higher-order theories of strain gradient plasticity (neglecting the plastic spin), the distortion gradient plasticity can predict some strengthening even if a quadratic defect energy is chosen. On the basis of the results of many FE analyses, concerned with (i) cyclic loading, (ii) switch in the higher-order boundary conditions during monotonic plastic loading, (iii) the use of non-quadratic defect energies, and (iv) the prediction of experimental data, we mainly show that (a) including the plastic spin contribution in a gradient plasticity theory is highly recommendable to model small-scale plasticity, (b) less-than-quadratic defect energies may help in describing the experimental results, but they may lead to anomalous cyclic behaviour, and (c) dissipative (unrecoverable) higher-order finite stresses are responsible for an unexpected mechanical response under non-proportional loading.

  7. Evaluating the Gradient of the Thin Wire Kernel

    Science.gov (United States)

    Wilton, Donald R.; Champagne, Nathan J.

    2008-01-01

    Recently, a formulation for evaluating the thin wire kernel was developed that employed a change of variable to smooth the kernel integrand, canceling the singularity in the integrand. Hence, the typical expansion of the wire kernel in a series for use in the potential integrals is avoided. The new expression for the kernel is exact and may be used directly to determine the gradient of the wire kernel, which consists of components that are parallel and radial to the wire axis.

  8. Integrating the Gradient of the Thin Wire Kernel

    Science.gov (United States)

    Champagne, Nathan J.; Wilton, Donald R.

    2008-01-01

    A formulation for integrating the gradient of the thin wire kernel is presented. This approach employs a new expression for the gradient of the thin wire kernel derived from a recent technique for numerically evaluating the exact thin wire kernel. This approach should provide essentially arbitrary accuracy and may be used with higher-order elements and basis functions using the procedure described in [4].When the source and observation points are close, the potential integrals over wire segments involving the wire kernel are split into parts to handle the singular behavior of the integrand [1]. The singularity characteristics of the gradient of the wire kernel are different than those of the wire kernel, and the axial and radial components have different singularities. The characteristics of the gradient of the wire kernel are discussed in [2]. To evaluate the near electric and magnetic fields of a wire, the integration of the gradient of the wire kernel needs to be calculated over the source wire. Since the vector bases for current have constant direction on linear wire segments, these integrals reduce to integrals of the form

  9. Radiation and scattering from thin wires in chiral media

    Science.gov (United States)

    Jaggard, Dwight L.; Liu, John C.; Grot, Annette; Pelet, Philippe

    1992-11-01

    The effect of chirality on thin win antennas and scatterers in unbounded chiral material is examined through the application of fundamental principles and the examination of several canonical examples. In particular, the interplay between normalized chirality and wire length is investigated to classify radiation and scattering patterns. Chirality induces rapid decay in the currents on such wires, resulting in mountain-peak-shaped current distributions characteristic of wire antennas and bow-tie-shaped current distributions characteristic of wire scatterers of sufficient length. These current distributions, in turn, cause radiation and scattering patterns which exhibit a chirality-dependent forbidden zone for both antennas and scatterers. In this zone, the fields are greatly reduced. These distinctive results lead naturally to the classification of wire scattering and radiation into subchiral, chiral, and superchiral regimes. All results are understood from the underlying physical principles of electromagnetic chirality, and are related to values of a dimensionless parameter involving normalized chirality and normalized wire length.

  10. Subcooled pool boiling on thin wire in microgravity

    Science.gov (United States)

    Zhao, J. F.; Wan, S. X.; Liu, G.; Yan, N.; Hu, W. R.

    2009-01-01

    A new set of experimental data of subcooled pool boiling on a thin wire in microgravity aboard the 22nd Chinese recoverable satellite is reported in the present paper. The temperature-controlled heating method is used. The results of the experiments in normal gravity before and after the flight experiment are also presented, and compared with those in microgravity. The working fluid is degassed R113 at 0.1 MPa and subcooled by 26C nominally. A thin platinum wire of 60μm in diameter and 30 mm in length is simultaneously used as heater and thermometer. It is found that the heat transfer of nucleate pool boiling is slightly enhanced in microgravity comparing with those in normal gravity. It is also found that the correlation of Lienhard and Dhir can predict the CHF with good agreement, although the range of the dimensionless radius is extended by three or more decades above the originally set limit. Three critical bubble diameters are observed in microgravity, which divide the observed vapor bubbles into four regimes with different sizes. Considering the Marangoni effect, a qualitative model is proposed to reveal the mechanism underlying the bubble departure processes, and a quantitative agreement can also be acquired.

  11. Onset of Vortices in Thin Superconducting Strips and Wires

    CERN Document Server

    Aranson, I S; Shapiro, B Y

    1994-01-01

    Spontaneous nucleation and the consequent penetration of vortices into thin superconducting films and wires, subjected to a magnetic field, can be considered as a nonlinear stage of primary instability of the current-carrying superconducting state. The development of the instability leads to the formation of a chain of vortices in strips and helicoidal vortex lines in wires. The boundary of instability was obtained analytically. The nonlinear stage was investigated by simulations of the time-dependent generalized Ginzburg-Landau equation.

  12. Radiation and scattering by thin-wire structures in the complex frequency domain. [electromagnetic theory for thin-wire antennas

    Science.gov (United States)

    Richmond, J. H.

    1974-01-01

    Piecewise-sinusoidal expansion functions and Galerkin's method are employed to formulate a solution for an arbitrary thin-wire configuration in a homogeneous conducting medium. The analysis is performed in the real or complex frequency domain. In antenna problems, the solution determines the current distribution, impedance, radiation efficiency, gain and far-field patterns. In scattering problems, the solution determines the absorption cross section, scattering cross section and the polarization scattering matrix. The electromagnetic theory is presented for thin wires and the forward-scattering theorem is developed for an arbitrary target in a homogeneous conducting medium.

  13. Application of ultra-thin polymer coating on metallic wires

    OpenAIRE

    Yu, Juan

    1992-01-01

    In this study, the coating of fine wires using hydrodynamic pressure technique has been investigated theoretically and experimentally. One of the principal aims of the project is to establish the minimum possible coating thickness on fine wires which can be applied by means of hydrodynamic technique. Models based on steady, uniform and laminar flow of Newtonian as well as non-Newtonian fluid for polymer coating for the process of plasto-hydrodynamic wire coating in a stepped bore unit have be...

  14. Edge-modulated perpendicular magnetic anisotropy in [Co/Pd]n and L10-FePt thin film wires

    Science.gov (United States)

    Zhang, Jinshuo; Ho, Pin; Currivan-Incorvia, Jean Anne; Siddiqui, Saima A.; Baldo, Marc A.; Ross, Caroline A.

    2015-11-01

    Thickness modulation at the edges of nanostructured magnetic thin films is shown to have important effects on their perpendicular magnetic anisotropy. Thin film wires with tapered edges were made from [Co/Pd]20 multilayers or L10-FePt films using liftoff with a double-layer resist. The effect of edge taper on the reversal process was studied using magnetic force microscopy and micromagnetic modeling. In [Co/Pd]20, the anisotropy was lower in the tapered edge regions which switched at a lower reverse field compared to the center of the wire. The L10-FePt wires showed opposite behavior with the tapered regions exhibiting higher anisotropy.

  15. Measurements of proportional scintillation in liquid xenon using thin wires

    CERN Document Server

    Aprile, E; Goetzke, L W; Fernandez, A J Melgarejo; Messina, M; Naganoma, J; Plante, G; Rizzo, A; Shagin, P; Wall, R

    2014-01-01

    Proportional scintillation in liquid xenon has a promising application in the field of direct dark matter detection, potentially allowing for simpler, more sensitive detectors. However, knowledge of the basic properties of the phenomenon as well as guidelines for its practical use are currently limited. We report here on measurements of proportional scintillation light emitted in liquid xenon around thin wires. The maximum proportional scintillation gain of $287^{+97}_{-75}$ photons per drift electron was obtained using 10 $\\mu$m diameter gold plated tungsten wire. The thresholds for electron multiplication and proportional scintillation are measured as $725^{+48}_{-139}$ and $412^{+10}_{-133}$ kV/cm, respectively. The threshold for proportional scintillation is in good agreement with a previously published result, while the electron multiplication threshold represents a novel measurement. A complete set of parameters for the practical use of the electron multiplication and proportional scintillation processe...

  16. High Hydrogen Loading of Thin Palladium Wires Through

    CERN Document Server

    Celani, F; Marini, P; Di Stefano, V; Nakamura, M; Pace, S; Vecchione, A; Mancini, A; Tripodi, P; Di Gioacchino, D

    2000-01-01

    A new protocol for the electrolytic loading of hydrogen (H) in thin palladium (Pd) wires has been developed. In order to increase the cathodic overvoltage, which is known to be the main parameter capable to enhance the electrolytic $9 H loading of Pd, the catalytic action of the Pd surface versus H-H recombination has been strongly reduced by precipitation of a thin layer of alkaline-earth carbonates on the cathode. A set of electrolytes has been employed, $9 containing small amounts of hydrochloric or sulphuric acid and strontium or calcium ions. The H loading has been continuously evaluated through ac measurements of the Pd wire resistance. Uncommonly low resistivity values, leading to $9 an estimate of exceptionally high H loading, have been observed. Evidence of the existence of a new phase in the very high H content region of the Pd-H system has been inferred on the basis of the determination of the temperature $9 coefficient of the electrical resistivity. For this purpose a thin layer of Hg was galvanic...

  17. Electromagnetic Excitation of a Thin Wire: A traveling-Wave Approach

    NARCIS (Netherlands)

    Bogerd, J.C.; Tijhuis, A.G.; Klaasen, J.J.A.

    1998-01-01

    An approximate representation for the current along a perfectly conducting straight thin wire is presented. The current is approximated in terms of pulsed waves that travel along the wire with the velocity of the exterior medium. At the ends of the wire, these pulses are partially reflected, with a

  18. Electromagnetic Excitation of a Thin Wire: A traveling-Wave Approach

    NARCIS (Netherlands)

    Bogerd, J.C.; Tijhuis, A.G.; Klaasen, J.J.A.

    1998-01-01

    An approximate representation for the current along a perfectly conducting straight thin wire is presented. The current is approximated in terms of pulsed waves that travel along the wire with the velocity of the exterior medium. At the ends of the wire, these pulses are partially reflected, with a

  19. submitter Dynamical Models of a Wire Scanner

    CERN Document Server

    Barjau, Ana; Dehning, Bernd

    2016-01-01

    The accuracy of the beam profile measurements achievable by the current wire scanners at CERN is limited by the vibrations of their mechanical parts. In particular, the vibrations of the carbon wire represent the major source of wire position uncertainty which limits the beam profile measurement accuracy. In the coming years, due to the Large Hadron Collider (LHC) luminosity upgrade, a wire traveling speed up to 20 $m s^{−1}$ and a position measurement accuracy of the order of 1 μm will be required. A new wire scanner design based on the understanding of the wire vibration origin is therefore needed. We present the models developed to understand the main causes of the wire vibrations observed in an existing wire scanner. The development and tuning of those models are based on measurements and tests performed on that CERN proton synchrotron (PS) scanner. The final model for the (wire + fork) system has six degrees-of-freedom (DOF). The wire equations contain three different excitation terms: inertia...

  20. Transient Analysis of Lumped Circuit Networks Loaded Thin Wires By DGTD Method

    KAUST Repository

    Li, Ping

    2016-03-31

    With the purpose of avoiding very fine mesh cells in the proximity of a thin wire, the modified telegrapher’s equations (MTEs) are employed to describe the thin wire voltage and current distributions, which consequently results in reduced number of unknowns and augmented Courant-Friedrichs-Lewy (CFL) number. As hyperbolic systems, both the MTEs and the Maxwell’s equations are solved by the discontinuous Galerkin time-domain (DGTD) method. In realistic situations, the thin wires could be either driven or loaded by circuit networks. The thin wire-circuit interface performs as a boundary condition for the thin wire solver, where the thin wire voltage and current used for the incoming flux evaluation involved in the DGTD analyzed MTEs are not available. To obtain this voltage and current, an auxiliary current flowing through the thin wire-circuit interface is introduced at each interface. Corresponding auxiliary equations derived from the invariable property of characteristic variable for hyperbolic systems are developed and solved together with the circuit equations established by the modified nodal analysis (MNA) modality. Furthermore, in order to characterize the field and thin wire interactions, a weighted electric field and a volume current density are added into the MTEs and Maxwell-Ampere’s law equation, respectively. To validate the proposed algorithm, three representative examples are presented.

  1. A hybrid DGTD scheme for transient analysis of electromagnetic field interactions on microwave systems loaded with thin wires

    KAUST Repository

    Li, Ping

    2015-10-15

    Use of the discontinuous Galerkin time-domain (DGTD) method for analyzing electromagnetic field interactions on microwave structures loaded with thin wires has been very limited despite its well-known advantages. Direct application of the three dimensional (3D) DGTD method to such structures calls for very fine volumetric discretizations in the proximity of the thin wires. In this work, to avoid this possible source of computational inefficiency, electromagnetic field interactions on thin wires and the rest of the structures are modeled separately using the modified telegrapher and Maxwell equations, respectively. Then, 1D and 3D DGTD methods are used to discretize them. The coupling between the two resulting matrix systems is realized by introducing equivalent source terms in each equation set. A weighted electric field obtained from the 3D discretization around the wire is introduced as a voltage source in the telegrapher equations. A volume current density obtained from the 1D discretization on the wire is introduced as a current source in the Ampere law equation. © 2015 IEEE.

  2. Vibration measurements of a wire scanner - Experimental setup and models

    Science.gov (United States)

    Herranz, Juan; Barjau, Ana; Dehning, Bernd

    2016-03-01

    In the next years the luminosity of the LHC will be significantly increased. This will require a much higher accuracy of beam profile measurement than actually achievable by the current wire scanner. The new performance demands a wire travelling speed up to 20 m s-1 and a position measurement accuracy of the order of 1 μm. The vibrations of the mechanical parts of the system and particularly the vibrations of the thin carbon wire have been identified as the major error sources of wire position uncertainty. Therefore the understanding of the wire vibrations has been given high priority for the design and operation of the new device. This article presents a new strategy to measure the wire vibrations based on the piezoresistive effect of the wire itself. An electronic readout system based on a Wheatstone bridge is used to measure the variation of the carbon wire resistance, which is directly proportional to the wire elongation caused by the oscillations.

  3. Modeling with FCA-Based Model of Microstructure Evolution of MgCa08 Alloy During Drawing of Thin Wire in Heated Die / Modelowanie Za Pomocą FCA Rozwoju Mikrostruktury Stopu MgCa08 Podczas Ciągnienia Cienkiego Drutu W Podgrzewanym Ciagadle

    Directory of Open Access Journals (Sweden)

    Svyetlichnyy D. S.

    2015-12-01

    Full Text Available The paper deals with a modeling of manufacturing process of thin wire of MgCa08 alloy used as biocompatible soluble threads for medical application. Some difficulties in material deformation subjected with its hexagonal structure can be solved with accurate establishment of the deformation conditions, especially temperature history of the whole process. In drawing process with heated die, wire is preheated in furnace and then deformed. The only narrow temperature range allows for multi-pass drawing without wire breaking. Diameter below 0.1 mm required for the final product makes very important the consideration of microstructure evolution because grain size is comparable with the wire dimensions. For this reason the problem is considered in the micro scale by using the frontal cellular automata (FCA-based model. The goals of present work are the development and validation of FCA-base model of microstructure evolution of MgCa0.8 magnesium alloy. To reach this objective, plastometric and relaxation tests of MgCA08 alloy were done on physical simulator GLEEBLE 3800. Results of the experimental studies were used for parameters identification of the hardening-softening model of the material. Then, initial microstructure and its evolution during the drawing passes were simulated with FCA-based model. FCA consider dislocation density and flow stress, hardening and softening including recovery and recrystallization, grain refinement and grain rotation, as well as grain growth. It allows one to obtain structures close to real ones. Two variants of the drawing process with different temperature history were considered. The deformation scheme was the same. Simulation results with following short discussion confirm usefulness of FCA-based model for explanation and selection of rational technological condition of thin wire drawing of MgCa08 alloy.

  4. Laser Non-Uniform Heating of Moving Thin Wires Below the Biot Number Criterion of Uniform Temperature

    Science.gov (United States)

    Wickramasooriya, Thiwanka; Vaidyanathan, Raj; Kar, Aravinda

    2016-06-01

    An analytic solution is obtained for three-dimensional quasi-steady state temperature distribution during laser heating of moving thin wires. The wire moves at a constant speed through a vacuum chamber, which is back-filled with an inert gas such as argon, and a laser beam of rectangular cross-section is incident on the wire. The ambient gas provides a convection heat transfer mechanism, which yields a Biot number, Bi, for the heating process to determine whether the temperature distribution would be uniform or nonuniform in the cross-section of the wire. Generally, the criterion of Bi less than 0.1 is applied to assume spatially uniform temperature distribution in a solid. The temperature distribution is determined for different Bi numbers and the variation of the temperature in the azimuthal direction is analyzed. The method of solution involves the Fourier transform in the azimuthal direction and the Hankel transform in the radial direction for a three-dimensional quasi-steady state heat conduction equation containing an advection term that accounts for the motion of the wire. The thermal and optical properties of the material is assumed to be constant in the temperature range of this study. The heat loss due to radiation heat transfer between the wire surface and the surrounding environment is neglected due to the small laser-heated surface area. Using this model, the temperature profile is studied for different process parameters such as the incident laser power, laser beam profile, Biot number, and wire speed.

  5. The Analysis of Thin Wires Using Higher-Order Elements and Basis Functions

    Energy Technology Data Exchange (ETDEWEB)

    Champagne, N J; Wilton, D R; Rockway, J W

    2006-01-23

    Thin wire analysis was applied to curved wire segments in [1], but a special procedure was needed to evaluate the self and near-self terms. The procedure involved associating the singular behavior with a straight segment tangent to the curved source segment, permitting use of algorithms for straight wires. Recently, a procedure that avoids the singularity extraction for straight wires was presented in [2-4]. In this paper, the approach in [4] is applied to curved (or higher-order) wires using a procedure similar to that used in [1] for singularity extraction. Here, the straight tangent segment is used to determine the quadrature rules to be used on the curved segment. The result is a formulation that allows for a general mixture of higher-order basis functions [5] and higher-order wire segments.

  6. In-situ transmission electron microscopy observation of electromigration in Au thin wires.

    Science.gov (United States)

    Murakami, Yosuke; Arita, Masashi; Hamada, Kouichi; Takahashi, Yasuo

    2012-11-01

    Electromigration of thin Au wire is studied by the use of in-situ transmission electron microscopy (TEM) techniques from the viewpoint of nanogap formation. We use a relatively wide Au wire as a starting material because the position-dependent structure change in the wire provides information of the thermal effect caused by the current flow. In-situ TEM observation, in which current measurements of the Au wire are simultaneously performed, reveals the process of the growth of voids and grains. Finally the formation of a nanogap by electromigration is observed doing with current measurements. All the results observed by in-situ TEM indicate the fact that the thermal effects or temperature increase in the wire region take an important role for the structure change caused by electromigration of Au in the wire. It is suggested that the position of the nanogap can roughly be arranged by setting the wire structure and current direction even though a relatively wide wire was used. The detailed observation by in-situ TEM also suggests that the control of heat generation in the wire makes the nanogap sharp because of the well-controlled recrystallization of Au nanowires.

  7. On the preparation and characterization of thin NiTi shape memory alloy wires for MEMS

    Directory of Open Access Journals (Sweden)

    Ausonio Tuissi

    2013-01-01

    Full Text Available Shape memory alloy (SMA wires are employed as actuators in small devices for consumer electronics, valves and automotive applications. Because of the continued miniaturization of all the industrial products, nowadays the tendency is to produce MEMS (micro electromechanical systems. Among the most promising functional MEMS materials, the thin SMA wires that are offering a rapid actuating response with high power/weigh ratio of the material, are attracting a world wide interest. This paper is aimed at showing the production process and the characterizations of thin NiTi shape memory wires. The activity was focused on drawing procedure and on functional and TEM characterizations of the final products. In particular, it was evaluated the performance of the SMA wires for actuators in terms of functional fatigue and thermo-mechanical properties by means of an experimental apparatus design ad hoc for these specific tests.

  8. Shearing Mechanism of Straight Thin Copper Wires at Connecting Terminal due to Lightning Current

    Institute of Scientific and Technical Information of China (English)

    HU Xiao-bo; Takahiro OTSUKA; Toru IWAO; Tsuginori INABA1

    2007-01-01

    When a lightning current is impressed through a copper wire,the copper wire would be melted.A straight thin copper wire with a diameter of 0.1 mm,is melted due to the specific melting Joule heating (j2t)m in an adiabatic condition.However,it has been recognized in the at the connecting terminal by a relatively low impulse current.Electro-magnetic mechanical shearing stress,etc.are discussed in addition to the conventional Joule heating. New broken mechanisms were presumed and proved in the additional experiments.

  9. Effect of variable physical properties on the thermal behavior of thin metallic wires under a DC field

    Science.gov (United States)

    Dey, Avishek Kumar; Ghosh, Abhishek Kumar; Ahmed, S. Reaz

    2016-07-01

    The effect of variable physical properties on the electro-thermal response of a thin metallic wire is investigated under a uniform direct current field. A general governing differential equation is derived for steady-state heat conduction in conductive wires with surface convection and Joule heating, in which the associated material as well as physical properties of the thermal and electrical problems are modeled as a function of temperature. The resulting nonlinear boundary-value problem is then solved by converting into an equivalent initial-value problem through a trial-and-error based numerical scheme. The electro-thermal characteristics of the wire are realized to be affected significantly when the physical properties are expressed as appropriate functions of temperature.

  10. Trapping of ultracold polar molecules with a Thin Wire Electrostatic Trap

    CERN Document Server

    Kleinert, J; Zabawa, P J; Bigelow, N P

    2007-01-01

    We describe the realization of a DC electric field trap for ultracold polar molecules, the Thin WIre electroStatic Trap (TWIST). The thin wires that form the electrodes of the TWIST allow us to superimpose the trap onto a magneto-optical trap (MOT). In our experiment, ultracold polar NaCs molecules in their electronic ground state are created in the MOT via photoassociation, achieving a continuous accumulation in the TWIST of molecules in low-field seeking states. Initial measurements show that the TWIST trap lifetime is limited only by the background pressure in the chamber.

  11. Study of proton generation using thin metal wires with a sharp tip

    Science.gov (United States)

    Maksimchuk, Anatoly; Fiksel, Gennady; Krushelnick, Karl; Bychenkov, Valery Yu.; Brantov, Andrey V.

    2016-10-01

    It was suggested to use the highly enhanced electric field close to a low-power-laser-illuminated metal tip for nanometric optical tweezers. Recently, a boost in proton acceleration by high-intensity laser using structured snow-like targets was observed and attributed mostly due to the field enhancement at the whisker tip. Here we report on a more controlled high-intensity laser experiment by using thin metal wires with a diameter of 20 microns with tips of different size ranging from 0.2 to 5.0 microns. 400 fs, 15 TW laser pulses were focused to an intensity of up to 3x1019 W/cm2 on a tungsten wire at different distances from the tip. We have observed two high-energy proton beams. One beam was produced through the Target Normal Sheet Acceleration (TNSA) mechanism and was perpendicular to the wire and the other one was observed from the wire tip and in the direction along the wire axis. Simultaneous measurements of maximum proton energies using CR-39 nuclear track detectors and high energy electrons using imaging plates in both direction were performed and will be presented. The experimental results were interpreted taking into account the generated electric and magnetic fields near the surface of the wire and at the wire tip as well as a strong collimated surface current along the wire. Work supported by US Department of Energy and NNSA.

  12. Properties Evaluation of Thin Microhardened Surface Layer of Tool Steel after Wire EDM

    Directory of Open Access Journals (Sweden)

    Ľuboslav Straka

    2016-04-01

    Full Text Available This paper describes results of experimental research on the thin microhardened surface layer of a machined surface that occurs in materials using wire electrical discharge machining (WEDM with brass wire electrode. The direct influence of microhardened surface layer on resulting machined surface quality of tool steel EN X210Cr12 (W.-Nr. 1.2080 was examined. The aim of the experiment was to contribute to the knowledge of mutual interactions between main WEDM technological parameters, the influence of these parameters on the total affected depth, and on the variation of microhardness of sub-surface layers of machined surface. Based on the microhardness experimental measurements, mathematical models were established by the Least Square Method (LSM in order to simulate and predict final quality of machined surface after WEDM. Recommendations are given for setting the main technological parameters of the discharge process concerning minimization of total microhardened surface layer depth and microhardened surface layer homogeneity along the whole cross-section profile of the machined surface.

  13. Manufacturing a thin wire electrostatic trap (TWIST) for ultracold polar molecules

    CERN Document Server

    Kleinert, J; Zabawa, P J; Bigelow, N P

    2007-01-01

    We present a detailed description on how to build a Thin WIre electroStatic Trap (TWIST) for ultracold polar molecules which can be superimposed onto a magneto optical trap. The required parts are easily accessible and inexpensive (bill of parts $<$\\$1000). A machine shop, a protected atmosphere glove box, and a fume hood are sufficient to manufacture the TWIST.

  14. Resonant Excitation of a Truncated Metamaterial Cylindrical Shell by a Thin Wire Monopole

    DEFF Research Database (Denmark)

    Kim, Oleksiy S.; Erentok, Aycan; Breinbjerg, Olav

    2009-01-01

    A truncated metamaterial cylindrical shell excited by a thin wire monopole is investigated using the integral equation technique as well as the finite element method. Simulations reveal a strong field singularity at the edge of the truncated cylindrical shell, which critically affects the matching...

  15. Growth Process Conditions of Tungsten Oxide Thin Films Using Hot-Wire Chemical Vapor Deposition

    NARCIS (Netherlands)

    Houweling, Z.S.; Geus, J.W.; de Jong, M.; Harks, P.P.R.M.L.; van der Werf, C.H.M.; Schropp, R.E.I.

    2011-01-01

    We report the growth conditions of nanostructured tungsten oxide (WO3−x) thin films using hot-wire chemical vapor deposition (HWCVD). Two tungsten filaments were resistively heated to various temperatures and exposed to an air flow at various subatmospheric pressures. The oxygen partial pressure was

  16. Quantum theory of the effect of grain boundaries on the electrical conductivity of thin films and wires

    Science.gov (United States)

    Moraga, Luis; Henriquez, Ricardo; Solis, Basilio

    2015-08-01

    We calculate the electrical conductivity of a metallic sample under the effects of distributed impurities and a random distribution of grain boundaries by means of a quantum mechanical procedure based on Kubo formula. Grain boundaries are represented either by a one-dimensional regular array of Dirac delta potentials (Mayadas and Shatzkes model) or by its three-dimensional extension (Szczyrbowski and Schmalzbauer model). We give formulas expressing the conductivity of bulk samples, thin films and thin wires of rectangular cross-sections in the case when the samples are bounded by perfectly flat surfaces. We find that, even in the absence of surface roughness, the conductivity in thin samples is reduced from its bulk value. If there are too many grain boundaries per unit length, or their scattering strength is high enough, there is a critical value Rc of the reflectivity R of an individual boundary such that the electrical conductivity vanishes for R >Rc. Also, the conductivity of thin wires shows a stepwise dependence on R. The effect of weak random variations in the strength or separation of the grain boundaries is computed by means of the method of correlation length. Finally, the resistivity of nanometric polycrystalline tungsten films reported in Choi et al. J. Appl. Phys. (2014) 115 104308 is tentatively analyzed by means of the present formalism.

  17. Thermal conductivity modeling of circular-wire nanocomposites

    Science.gov (United States)

    Hsieh, Tse-Yang; Yang, Jaw-Yen

    2010-08-01

    A phonon Boltzmann equation solver using multiblock-structured grid system is developed and applied to study transverse thermal transport in silicon-germanium circular-wire nanocomposite (silicon nanowires embedded in germanium host matrix). Past studies usually assume geometric simplification for the circular-wire nanocomposite, so the heat transfer is actually modeled in a square-wire nanocomposite. To demonstrate geometry effect, phonon transport in both the circular-wire and square-wire nanocomposites are investigated with various wire spacings, volume fractions, and dimensions. In ballistic phonon transport, due to the smoothness of circular shape, the circular wire imposes less thermal resistance than the square wire. Nevertheless, in the geometric simplification, the wire spacing of the square-wire nanocomposite is larger than that of the circular-wire nanocomposite. The usual geometric simplification can overestimate the thermal conductivity of the circular-wire nanocomposite. The obtained results can provide essential information for the development of bulk-nanostructured thermoelectric devices.

  18. Model of Carbon Wire Heating in Accelerator Beam

    CERN Document Server

    Sapinski, M

    2008-01-01

    A heat flow equation with beam-induced heating and various cooling processes for a carbon wire passing through a particle beam is solved. Due to equation nonlinearity a numerical approach based on discretization of the wire movement is used. Heating of the wire due to the beam-induced electromagnetic field is taken into account. An estimation of the wire sublimation rate is made. The model is tested on SPS, LEP and Tevatron Main Injector data. Results are discussed and conclusions about limits of Wire Scanner operation on LHC beams are drawn.

  19. An Electrostatic Model of Split-Gate Quantum Wires

    OpenAIRE

    Sun, Yinlong; Kirczenow, George; Sachrajda, Andrew. S.; Feng, Yan

    1995-01-01

    We present a theoretical model of split-gate quantum wires that are fabricated from GaAs-AlGaAs heterostructures. The model is built on the physical properties of donors and of semiconductor surfaces, and considerations of equilibrium in such systems. Based on the features of this model, we have studied different ionization regimes of quantum wires, provided a method to evaluate the shallow donor density, and calculated the depletion and pinchoff voltages of quantum wires both before and afte...

  20. Study of Electromagnetic Scattering From Material Object Doped Randomly With Thin Metallic Wires Using Finite Element Method

    Science.gov (United States)

    Deshpande, Manohar D.

    2005-01-01

    A new numerical simulation method using the finite element methodology (FEM) is presented to study electromagnetic scattering due to an arbitrarily shaped material body doped randomly with thin and short metallic wires. The FEM approach described in many standard text books is appropriately modified to account for the presence of thin and short metallic wires distributed randomly inside an arbitrarily shaped material body. Using this modified FEM approach, the electromagnetic scattering due to cylindrical, spherical material body doped randomly with thin metallic wires is studied.

  1. Modeling and Dynamical Behavior of Rotating Composite Shafts with SMA Wires

    Directory of Open Access Journals (Sweden)

    Yongsheng Ren

    2014-01-01

    Full Text Available A dynamical model is developed for the rotating composite shaft with shape-memory alloy (SMA wires embedded in. The rotating shaft is represented as a thin-walled composite of circular cross-section with SMA wires embedded parallel to shaft’s longitudinal axis. A thermomechanical constitutive equation of SMA proposed by Brinson is employed and the recovery stress of the constrained SMA wires is derived. The equations of motion are derived based on the variational-asymptotical method (VAM and Hamilton’s principle. The partial differential equations of motion are reduced to the ordinary differential equations of motion by using the Galerkin method. The model incorporates the transverse shear, rotary inertia, and anisotropy of composite material. Numerical results of natural frequencies and critical speeds are obtained. It is shown that the natural frequencies of the nonrotating shaft and the critical rotating speed increase as SMA wire fraction and initial strain increase and the increase in natural frequencies becomes more significant as SMA wire fraction increases. The initial strain of SMA wires appears to have marginal effect on dynamical behaviors of the shaft. The actuation performance of SMA wires is found to be closely related to the ply-angle.

  2. Polarization-dependent thin-film wire-grid reflectarray for terahertz waves

    Energy Technology Data Exchange (ETDEWEB)

    Niu, Tiaoming [School of Electrical and Electronic Engineering, The University of Adelaide, Adelaide, South Australia 5005 (Australia); School of Information Science and Engineering, Lanzhou University, Lanzhou 730000 (China); Upadhyay, Aditi; Bhaskaran, Madhu; Sriram, Sharath [Functional Materials and Microsystems Research Group, RMIT University, Melbourne, Victoria 3001 (Australia); Withayachumnankul, Withawat [School of Electrical and Electronic Engineering, The University of Adelaide, Adelaide, South Australia 5005 (Australia); Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, 2-12-1-S9-3, Ookayama, Meguro-ku, Tokyo 152-8552 (Japan); Headland, Daniel; Abbott, Derek; Fumeaux, Christophe, E-mail: cfumeaux@eleceng.adelaide.edu.au [School of Electrical and Electronic Engineering, The University of Adelaide, Adelaide, South Australia 5005 (Australia)

    2015-07-20

    A thin-film polarization-dependent reflectarray based on patterned metallic wire grids is realized at 1 THz. Unlike conventional reflectarrays with resonant elements and a solid metal ground, parallel narrow metal strips with uniform spacing are employed in this design to construct both the radiation elements and the ground plane. For each radiation element, a certain number of thin strips with an identical length are grouped to effectively form a patch resonator with equivalent performance. The ground plane is made of continuous metallic strips, similar to conventional wire-grid polarizers. The structure can deflect incident waves with the polarization parallel to the strips into a designed direction and transmit the orthogonal polarization component. Measured radiation patterns show reasonable deflection efficiency and high polarization discrimination. Utilizing this flexible device approach, similar reflectarray designs can be realized for conformal mounting onto surfaces of cylindrical or spherical devices for terahertz imaging and communications.

  3. Charge production in thin gap multi-wire chambers

    CERN Document Server

    Mincer, A I; Goldberg, J J; Gernitzky, Y; Lazic, D; Lupu, N Z; Robins, S; Rozen, Y; Tarem, S

    2000-01-01

    Resistive cathode thin gap chambers (TGCs) have been used as particle detectors in high-energy physics experiments for more than a decade. A quantitative understanding of charge production mechanisms in TGCs has been developed and a simulation program produced to accurately describe the expected response from a chamber as a function of its design and operating parameters. This simulation is based upon a description of the processes of electron cluster production, drift and avalanche effects and space charge contributions from residual ions. Improved measurements of chamber performance are presented, and the parameters of the simulation have been fitted to these data yielding values consistent with estimates based on the physical mechanisms involved. Sensitivity of chamber timing and amplification properties to operating parameters is discussed.

  4. Transient Response of Thin Wire above a Layered Half-Space Using TDIE/FDTD Hybrid Method

    Directory of Open Access Journals (Sweden)

    Bing Wei

    2012-01-01

    Full Text Available The TDIE/FDTD hybrid method is applied to calculate the transient responses of thin wire above a lossy layered half-space. The time-domain reflection of the layered half space is computed by one-dimensional modified FDTD method. Then, transient response of thin wire induced by two excitation sources (the incident wave and reflected wave is calculated by TDIE method. Finally numerical results are given to illustrate the feasibility and high efficiency of the presented scheme.

  5. Analysis of Microstructure and Damage Evolution in Ultra-Thin Wires of the Magnesium Alloy MgCa0.8 at Multipass Drawing

    Science.gov (United States)

    Milenin, Andrij; Kustra, Piotr; Byrska-Wójcik, Dorota; Grydin, Olexandr; Schaper, Mirko; Mentlein, Thorben; Gerstein, Gregory; Nürnberger, Florian

    2016-12-01

    A combined multipass hot and cold drawing process was implemented to manufacture ultra-thin wires of the magnesium alloy MgCa0.8 with a final diameter of 0.05 mm. Numerical simulations were applied to design the drawing process of 40 passes regarding the microstructure evolution. To parametrize the model, in situ tensile tests were performed. Analysis of the MgCa0.8 wires featuring diameters below 0.1 mm revealed no intergranular crack initiation. The grain size of the ultra-thin wires is within the range of 30-500 nm with grains elongated in the drawing direction. The fine-grained microstructure provides high mechanical strength properties.

  6. Numerical model for electrical explosion of copper wires in water

    Science.gov (United States)

    Chung, Kyoung-Jae; Lee, Kern; Hwang, Y. S.; Kim, Deok-Kyu

    2016-11-01

    This paper presents a simple but quite accurate numerical model for analyzing electrical explosion of copper wires in water. The numerical model solves a circuit equation coupled with one-dimensional magneto-hydrodynamic (MHD) equations with the help of appropriate wide-range equation of state (EOS) and electrical conductivity for copper. The MHD equations are formulated in a Lagrangian form to identify the interface between the wire and surrounding water clearly. A quotidian EOS (QEOS) that is known as the simplest form of EOS is utilized to build wide-range EOS for copper. In the QEOS, we consider the liquid-vapor phase transition, which is critical in analyzing the wire explosion system. For the electrical conductivity of copper, a semi-empirical set of equations covering from solid state to partially ionized plasma state are employed. Experimental validation has been performed with copper wires of various diameters, which are exploded by a microsecond timescale pulsed capacitive discharge. The simulation results show excellent agreements with the experimental results in terms of temporal motions of a plasma channel boundary and a shock front as well as current and voltage waveforms. It is found that the wire explodes (vaporizes) along the liquid branch of a binodal curve irrespective of wire dimension and operating voltage. After the explosion, the wire becomes a plasma state right away or after the current pause (dwell), depending on the operating conditions. It is worth noting that such a peculiar characteristic of wire explosion, i.e., current pause and restrike, is well simulated with the present numerical model. In particular, it is shown that the wire cools down along the vapor branch of the binodal curve during the current dwell, due to a significant difference of thermodynamic characteristics across the binodal curve. The influence of radiation for studying nonideal plasmas with a wire explosion technique and a physical process for shock wave formation

  7. Wire Bonder: Kulicke and Soffa Model 4526

    Data.gov (United States)

    Federal Laboratory Consortium — Description:CORAL Name: Wire BonderNeeds Description.Scientific Opportunities / Applications:Wedge bonderSemi-automatic and manual modesIndependent Z-axis control,...

  8. Attachment of lead wires to thin film thermocouples mounted on high temperature materials using the parallel gap welding process

    Science.gov (United States)

    Holanda, Raymond; Kim, Walter S.; Pencil, Eric; Groth, Mary; Danzey, Gerald A.

    1990-01-01

    Parallel gap resistance welding was used to attach lead wires to sputtered thin film sensors. Ranges of optimum welding parameters to produce an acceptable weld were determined. The thin film sensors were Pt13Rh/Pt thermocouples; they were mounted on substrates of MCrAlY-coated superalloys, aluminum oxide, silicon carbide and silicon nitride. The entire sensor system is designed to be used on aircraft engine parts. These sensor systems, including the thin-film-to-lead-wire connectors, were tested to 1000 C.

  9. The Modeling of Vibration Damping in SMA Wires

    Energy Technology Data Exchange (ETDEWEB)

    Reynolds, D R; Kloucek, P; Seidman, T I

    2003-09-16

    Through a mathematical and computational model of the physical behavior of shape memory alloy wires, this study shows that localized heating and cooling of such materials provides an effective means of damping vibrational energy. The thermally induced pseudo-elastic behavior of a shape memory wire is modeled using a continuum thermodynamic model and solved computationally as described by the authors in [23]. Computational experiments confirm that up to 80% of an initial shock of vibrational energy can be eliminated at the onset of a thermally-induced phase transformation through the use of spatially-distributed transformation regions along the length of a shape memory alloy wire.

  10. Measurement and modeling of dispersive pulse propagation in draw wire waveguides

    Science.gov (United States)

    Madaras, Eric I.; Kohl, Thomas W.; Rogers, Wayne P.

    1995-01-01

    An analytical model of dispersive pulse propagation in semi-infinite cylinders due to transient axially symmetric end conditions has been experimentally investigated. Specifically, the dispersive propagation of the first axially symmetric longitudinal mode in thin wire waveguides, which have ends in butt contact with longitudinal piezoelectric ultrasonic transducers, is examined. The method allows for prediction of a propagated waveform given a measured source waveform, together with the material properties of the cylinder. Alternatively, the source waveform can be extracted from measurement of the propagated waveform. The material properties required for implementation of the pulse propagation model are determined using guided wave phase velocity measurements. Hard tempered aluminum 1100 and 304 stainless steel wires, with 127, 305, and 406 micron diam., were examined. In general, the drawn wires were found to behave as transversely isotropic media.

  11. Industrialization of Hot Wire Chemical Vapor Deposition for thin film applications

    Energy Technology Data Exchange (ETDEWEB)

    Schropp, R.E.I., E-mail: r.e.i.schropp@tue.nl

    2015-11-30

    The consequences of implementing a Hot Wire Chemical Vapor Deposition (HWCVD) chamber into an existing in-line or roll-to-roll reactor are described. The hardware and operation of the HWCVD production reactor is compared to that of existing roll-to-roll reactors based on Plasma Enhanced Chemical Vapor Deposition. The most important consequences are the technical consequences and the economic consequences, which are both discussed. The technical consequences are adaptations needed to the hardware and to the processing sequences due to the different interaction of the HWCVD process with the substrate and already deposited layers. The economic consequences are the reduced investments in radio frequency (RF) supplies and RF components. This is partially offset by investments that have to be made in higher capacity pumping systems. The most mature applications of HWCVD are moisture barrier coatings for thin film flexible devices such as Organic Light Emitting Diodes and Organic Photovoltaics, and passivation layers for multicrystalline Si solar cells, high mobility field effect transistors, and silicon heterojunction cells (also known as heterojunction cells with intrinsic thin film layers). Another example is the use of Si in thin film photovoltaics. The cost perspective per unit of thin film photovoltaic product using HWCVD is estimated at 0.07 €/Wp for the Si thin film component. - Highlights: • Review of consequences of implementing Hot Wire CVD into a manufacturing plant • Aspects of scaling up to large area and continuous manufacturing are discussed • Economic advantage of introducing a HWCVD process in a production system is estimated • Using HWCVD, the cost for the Si layers in photovoltaic products is 0.08 €/Wp.

  12. Direct drag and hot-wire measurements on thin-element riblet arrays

    Science.gov (United States)

    Wilkinson, S. P.; Lazos, B. S.

    1987-01-01

    An experimental study of stream wise, near-wall, thin-element riblet arrays under a turbulent boundary layer has been conducted in low-speed air. Hot-wire data show that a single, isolated thin-element riblet causes formation of counter-rotating vortex-pairs with a spanwise wavelength of 130 viscous lengths. Abrupt shifts in turbulence intensity magnitude and peak location are observed for streamwise riblet arrays as spanwise riblet spacing is varied. Direct drag measurements show net drag reduction (up to 8.5 percent) over a wide range of riblet spacings along with behavior at discrete non-dimensional spacings indicative of vortex activity. Overall, the data suggest that more than one drag reduction mechanism may be involved.

  13. Deposition of thermal and hot-wire chemical vapor deposition copper thin films on patterned substrates.

    Science.gov (United States)

    Papadimitropoulos, G; Davazoglou, D

    2011-09-01

    In this work we study the hot-wire chemical vapor deposition (HWCVD) of copper films on blanket and patterned substrates at high filament temperatures. A vertical chemical vapor deposition reactor was used in which the chemical reactions were assisted by a tungsten filament heated at 650 degrees C. Hexafluoroacetylacetonate Cu(I) trimethylvinylsilane (CupraSelect) vapors were used, directly injected into the reactor with the aid of a liquid injection system using N2 as carrier gas. Copper thin films grown also by thermal and hot-wire CVD. The substrates used were oxidized silicon wafers on which trenches with dimensions of the order of 500 nm were formed and subsequently covered with LPCVD W. HWCVD copper thin films grown at filament temperature of 650 degrees C showed higher growth rates compared to the thermally ones. They also exhibited higher resistivities than thermal and HWCVD films grown at lower filament temperatures. Thermally grown Cu films have very uniform deposition leading to full coverage of the patterned substrates while the HWCVD films exhibited a tendency to vertical growth, thereby creating gaps and incomplete step coverage.

  14. Improvements to Wire Bundle Thermal Modeling for Ampacity Determination

    Science.gov (United States)

    Rickman, Steve L.; Iannello, Christopher J.; Shariff, Khadijah

    2017-01-01

    Determining current carrying capacity (ampacity) of wire bundles in aerospace vehicles is critical not only to safety but also to efficient design. Published standards provide guidance on determining wire bundle ampacity but offer little flexibility for configurations where wire bundles of mixed gauges and currents are employed with varying external insulation jacket surface properties. Thermal modeling has been employed in an attempt to develop techniques to assist in ampacity determination for these complex configurations. Previous developments allowed analysis of wire bundle configurations but was constrained to configurations comprised of less than 50 elements. Additionally, for vacuum analyses, configurations with very low emittance external jackets suffered from numerical instability in the solution. A new thermal modeler is presented allowing for larger configurations and is not constrained for low bundle infrared emissivity calculations. Formulation of key internal radiation and interface conductance parameters is discussed including the effects of temperature and air pressure on wire to wire thermal conductance. Test cases comparing model-predicted ampacity and that calculated from standards documents are presented.

  15. Reaction Between Thin Gold Wires and Pb-Sn-In Solder (37.5%, 37.5%, 25%), Part A: The Radial Reaction Inside The Solder Mounds, Its Linear Reaction Model, Statistical Variation of Reaction Rate, and Induced Structural Changes In The Solder Mounds.

    Energy Technology Data Exchange (ETDEWEB)

    Siekhaus, W J

    2011-01-19

    Thermodynamics favors the reaction between indium and gold, since the heat of formation of AuIn{sub 2} is 6 kcal/mole, substantially larger than the heat of formation of any other possible reaction product. Thermodynamic equilibrium between gold and the elements in the solder mound is reached only when ALL gold is converted to AuIn{sub 2}. There are two aspects to this conversion: (A) the reaction WITHIN the solder mound (called here 'radial reaction') and (B) the reaction OUTSIDE the solder mound (called here 'axial reaction') and the transition from (A) to (B). The reaction between thin gold detonator wires and the In/Pb/Sn solder mound in older detonators has been looked at repeatedly. There are, in addition, two studies which look at the reaction between indium and gold in planar geometry. All data are shown in tables I to V. It is the objective of this section dealing with aspect (A), to combine all of these results into a reaction model and to use this reaction model to reliably and conservatively predict the gold-solder reaction rate of soldered gold bridge-wires as a function of storage temperature and time.

  16. High performance patch antenna using circular split ring resonators and thin wires employing electromagnetic coupling improvement

    Science.gov (United States)

    Abdelrehim, Adel A. A.; Ghafouri-Shiraz, H.

    2016-09-01

    In this paper, three dimensional periodic structure composed of circular split ring resonators and thin wires is used to improve the performance of a microstrip patch antenna. The three dimensional periodic structure is placed at the top of the patch within a specific separation distance to construct the proposed antenna. The radiated electromagnetic waves intensity of the proposed antenna is improved compared with the conventional patch antenna due to the electric and magnetic coupling enhancements. These enhancements occur between the patch and the periodic structure resonators and between the different resonator pairs of the periodic structure. As a result, the electric and the magnetic fields at the top of the patch are improved, the radiated electromagnetic beam size reduces which results in a highly focused beam and hence the antenna directivity and gain are improved, while the beam are is reduced. The proposed antenna has been designed and simulated using CST microwave studio at 10 GHz. An infinite two dimensional periodicity unit cell of circular split ring resonator and thin wire is designed to resonate at a 10 GHz and simulated in CST software, the scattering parameters are extracted, the results showed that the infinite periodicity two dimensional structure has a pass band frequency response of good transmission and reflection characteristics around 10 GHz. The infinite periodicity of the two dimensional periodic structure is then truncated and multi layers of such truncated structure is used to construct a three dimensional periodic structure. A parametric analysis has been performed on the proposed antenna incorporated with the three dimensional periodic structure. The impacts of the separation distance between the patch and three dimensional periodic structures and the size of the three dimensional periodic structure on the radiation and impedance matching parameters of the proposed antenna are studied. For experimental verification, the proposed

  17. Modelling of drawing and rolling of high carbon flat wires

    Science.gov (United States)

    Bobadilla, C.; Persem, N.; Foissey, S.

    2007-04-01

    In order to meet customer requirements, it is necessary to develop new flat wires with a high tensile strength and a high width/thickness ratio. These products are manufactured from wire rod. The first step is to draw the wire until we have the required mechanical properties and required surface area of the section. After this, the wire is rolled from a round to a rectangular section. During the flat rolling process it can be reduced by more than 50%. Then the wire is exposed to a high level of stress during this process. Modelling allows us to predetermine this stress level, taking into account the final dimensions and the mechanical properties, thus optimising both rolling and drawing process. Forge2005 was used in order to simulate these processes. The aim of this study is to determine the value of residual stresses after drawing and so to optimise rolling. Indeed, the highest stress values are reached at this step of the process by changing the section of the wire from a round to a rectangular one. In order to evaluate the stress value accuracy for high strain levels, a behaviour law has been identified. This is a result of tensile tests carried out at each step of the drawing process. Finally, a multi-axial damage criterion was implemented using Forge2005. The optimisation of the rolling is directly linked to the minimisation of this criterion.

  18. Degradation of a tantalum filament during the hot-wire CVD of silicon nitride thin films

    Energy Technology Data Exchange (ETDEWEB)

    Oliphant, C.J. [Department of Physics, University of the Western Cape, Private Bag X17, Bellville 7535 (South Africa); National Metrology Institute of South Africa, Private Bag X34, Lynwood Ridge, Pretoria 0040 (South Africa); Arendse, C.J., E-mail: cjarendse@uwc.ac.za [Department of Physics, University of the Western Cape, Private Bag X17, Bellville 7535 (South Africa); Muller, T.F.G. [Department of Physics, University of the Western Cape, Private Bag X17, Bellville 7535 (South Africa); Jordaan, W.A. [National Metrology Institute of South Africa, Private Bag X34, Lynwood Ridge, Pretoria 0040 (South Africa); Knoesen, D. [Department of Physics, University of the Western Cape, Private Bag X17, Bellville 7535 (South Africa)

    2015-01-30

    Electron backscatter diffraction revealed that during the hot-wire deposition of silicon nitride, a tantalum filament partially transformed to some of its nitrides and silicides. The deposition of an encapsulating silicon nitride layer occurred at the cooler filament ends. Time-of-flight secondary ion mass spectroscopy disclosed the presence of hydrogen, nitrogen and silicon containing ions within the aged filament bulk. Hardness measurements revealed that the recrystallized tantalum core experienced significant hardening, whereas the silicides and nitrides were harder but more brittle. Crack growth, porosity and the different thermal expansion amongst the various phases are all enhanced at the hotter centre regions, which resulted in failure at these areas. - Highlights: • Tantalum filament degrades and fails during hot-wire CVD of silicon nitride thin films. • An encapsulating silicon nitride layer is deposited at the cooler ends. • Electron backscatter diffraction reveals Ta-silicides and -nitrides with a Ta core. • Filament failure occurs at hot centre regions due to different mechanical properties of Ta, its silicides and nitrides.

  19. Variation of Charge Distribution and Capacitance on Thin Wire Using the Method of Moments

    Directory of Open Access Journals (Sweden)

    Mohamed Louzazni

    2013-09-01

    Full Text Available In this paper, we attempting to determine the linear charge density and capacitance on a finite straight segment of thin charged conducting wire of length L=1 m and radius r. we assume that the charge density piecewise constant over the length and the electric potential are is one volt. If the radius are very small compared to the length r<wire in N=100 sub segments, each of length. We choose N points of observation on the surface and the charge density are piecewise constant onto each segment. The integral equation will be transformed to linear equation in N equation with N unknown system. We use the method of moments for solving this system and we obtained a Toeplitz matrix, the results shows the charge density for N=100 is represented on the low levels of discretisation, and the decreasing of the radius increaser the fidelity of the results.

  20. Temperature dependent polarization of the thermal radiation emitted by thin, hot tungsten wires

    CERN Document Server

    Borghesani, A F; Ruoso, G

    2013-01-01

    We report measurements of the temperature $T $ dependence of the linear polarization $ $ of the thermal radiation emitted by thin, incandescent tungsten wires. We investigate an interval ranging from a little above room temperature up to melting, $T_m= 3695\\,$K. These are the first measurements in such wide a range. We found that $ $ decreases with increasing temperature. We obtained a satisfactory agreement with the theoretical predictions based on the Kirchhoff's law by using a Drude-type formula for the optical properties of tungsten. This formula was tested and its parameters were assessed as valid for $T\\leq 2400 \\,$K and for wavelengths in the range from visible up to $\\lambda\\approx 2.6\\,\\mu$m. We have extended the range of validity of this formula for $T$ up to $T_m$ and for $\\lambda$ up to $\\approx 12\\,\\mu$m.

  1. Dynamics of Discrete Bubble in Nucleate Pool Boiling on Thin Wires in Micro-gravity

    Institute of Scientific and Technical Information of China (English)

    Shixin WAN; Jianfu ZHAO; Gang LIU

    2009-01-01

    A space experiment on bubble behavior and heat transfer in subcooled pool boiling phenomenon has been per-formed utilizing the temperature-controlled pool boiling (TCPB) device both in normal gravity in the laboratory and in microgravity aboard the 22no Chinese recoverable satellite. The fluid is degassed Rl13 at 0.1 Mpa and subcooled by 26℃ nominally. A thin platinum wire of 60 μm in diameter and 30 mm in length is simultaneously used as heater and thermometer. Only the dynamics of the vapor bubbles, particularly the lateral motion and the departure of discrete vapor bubbles in nucleate pool boiling are reported and analyzed in the present paper. It's found that these distinct behaviors can be explained by the Marangoni convection in the liquid surrounding vapor bubbles. The origin of the Marangoni effect is also discussed.

  2. Using hot wire and initiated chemical vapor deposition for gas barrier thin film encapsulation

    Energy Technology Data Exchange (ETDEWEB)

    Spee, D.A., E-mail: diederickspee@gmail.com; Rath, J.K.; Schropp, R.E.I.

    2015-01-30

    Hot wire CVD (HWCVD) and initiated CVD (iCVD) are very well suited deposition techniques for the fabrication of transparent thin film gas barriers. Single inorganic or organic layers, however, face challenges, which are hard to overcome: unavoidable defects and low intrinsic barrier function. We demonstrate that by combining inorganic HWCVD films and organic iCVD films, a water vapor transmission rate a low as 5 ∗ 10{sup −6} g/m{sup 2}/day at 60 °C and 90% RH for a simple pinhole free three layer structure is obtained even with non-optimized individual layers. Given the 100 °C deposition temperature, the layer stacks can be deposited on any sensitive electronic device.

  3. Non-classical crystallization of silicon thin films during hot wire chemical vapor deposition

    Science.gov (United States)

    Jung, Jae-Soo; Lee, Sang-Hoon; Kim, Da-Seul; Kim, Kun-Su; Park, Soon-Won; Hwang, Nong-Moon

    2017-01-01

    The deposition behavior of silicon films by hot wire chemical vapor deposition (HWCVD) was approached by non-classical crystallization, where the building block of deposition is a nanoparticle generated in the gas phase of the reactor. The puzzling phenomenon of the formation of an amorphous incubation layer on glass could be explained by the liquid-like property of small charged nanoparticles (CNPs), which are generated in the initial stage of the HWCVD process. Using the liquid-like property of small CNPs, homo-epitaxial growth as thick as 150 nm could be successfully grown on a silicon wafer at 600 °C under the processing condition where CNPs as small as possible could be supplied steadily by a cyclic process which periodically resets the process. The size of CNPs turned out to be an important parameter in the microstructure evolution of thin films.

  4. Time domain analysis of thin-wire antennas over lossy ground using the reflection-coefficient approximation

    NARCIS (Netherlands)

    Fernández Pantoja, M.; Yarovoy, A.G.; Rubio Bretones, A.; González García, S.

    2009-01-01

    This paper presents a procedure to extend the methods of moments in time domain for the transient analysis of thin-wire antennas to include those cases where the antennas are located over a lossy half-space. This extended technique is based on the reflection coefficient (RC) approach, which approxim

  5. Heat transfer enhancement on thin wires in superfluid helium forced flows

    CERN Document Server

    Duri, Davide; Moro, Jean-Paul; Roche, Philippe-Emmanuel; Diribarne, Pantxo

    2014-01-01

    In this paper, we report the first evidence of an enhancement of the heat transfer from a heated wire by an external turbulent flow of superfluid helium. We used a standard Pt-Rh hot-wire anemometer and overheat it up to 21 K in a pressurized liquid helium turbulent round jet at temperatures between 1.9 K and 2.12 K. The null-velocity response of the sensor can be satisfactorily modeled by the counter flow mechanism while the extra cooling produced by the forced convection is found to scale similarly as the corresponding extra cooling in classical fluids. We propose a preliminary analysis of the response of the sensor and show that -contrary to a common assumption- such sensor can be used to probe local velocity in turbulent superfluid helium.

  6. Growth process conditions of tungsten oxide thin films using hot-wire chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Houweling, Z. Silvester, E-mail: Z.S.Houweling@uu.nl [Nanophotonics - Physics of Devices, Debye Institute for Nanomaterials Science, Utrecht University, Princetonlaan 4, 3584 CB Utrecht (Netherlands); Geus, John W. [Electron Microscopy, Utrecht University, Padualaan 8, 3584 CH Utrecht (Netherlands); Jong, Michiel de; Harks, Peter-Paul R.M.L.; Werf, Karine H.M. van der; Schropp, Ruud E.I. [Nanophotonics - Physics of Devices, Debye Institute for Nanomaterials Science, Utrecht University, Princetonlaan 4, 3584 CB Utrecht (Netherlands)

    2011-12-15

    Highlights: Black-Right-Pointing-Pointer Process parameters to control hot-wire CVD of WO{sub 3-x} are categorized. Black-Right-Pointing-Pointer Growth time, oxygen partial pressure, filament and substrate temperature are varied. Black-Right-Pointing-Pointer Chemical and crystal structure, optical bandgap and morphology are determined. Black-Right-Pointing-Pointer Oxygen partial pressure determines the deposition rate up to as high as 36 {mu}m min{sup -1}. Black-Right-Pointing-Pointer Nanostructures, viz. wires, crystallites and closed crystallite films, are controllably deposited. - Abstract: We report the growth conditions of nanostructured tungsten oxide (WO{sub 3-x}) thin films using hot-wire chemical vapor deposition (HWCVD). Two tungsten filaments were resistively heated to various temperatures and exposed to an air flow at various subatmospheric pressures. The oxygen partial pressure was varied from 6.0 Multiplication-Sign 10{sup -6} to 1.0 mbar and the current through the filaments was varied from 4.0 to 9.0 A, which constitutes a filament temperature of 1390-2340 Degree-Sign C in vacuum. It is observed that the deposition rate of the films is predominantly determined by the oxygen partial pressure; it changes from about 1 to about 36,000 nm min{sup -1} in the investigated range. Regardless of the oxygen partial pressure and filament temperature used, thin films with a nanogranular morphology are obtained, provided that the depositions last for 30 min or shorter. The films consist either of amorphous or partially crystallized WO{sub 3-x} with high averaged transparencies of over 70% and an indirect optical band gap of 3.3 {+-} 0.1 eV. A prolonged deposition time entails an extended exposure of the films to thermal radiation from the filaments, which causes crystallization to monoclinic WO{sub 3} with diffraction maxima due to the (0 0 2), (2 0 0) and (0 2 0) crystallographic planes, furthermore the nanograins sinter and the films exhibit a cone

  7. Finite element modeling of superelastic nickel-titanium orthodontic wires.

    Science.gov (United States)

    Naceur, Ines Ben; Charfi, Amin; Bouraoui, Tarak; Elleuch, Khaled

    2014-11-28

    Thanks to its good corrosion resistance and biocompatibility, superelastic Ni–Ti wire alloys have been successfully used in orthodontic treatment. Therefore, it is important to quantify and evaluate the level of orthodontic force applied to the bracket and teeth in order to achieve tooth movement. In this study, three dimensional finite element models with a Gibbs-potential-based-formulation and thermodynamic principles were used. The aim was to evaluate the influence of possible intraoral temperature differences on the forces exerted by NiTi orthodontic arch wires with different cross sectional shapes and sizes. The prediction made by this phenomenological model, for superelastic tensile and bending tests, shows good agreement with the experimental data. A bending test is simulated to study the force variation of an orthodontic NiTi arch wire when it loaded up to the deflection of 3 mm, for this task one half of the arch wire and the 3 adjacent brackets were modeled. The results showed that the stress required for the martensite transformation increases with the increase of cross-sectional dimensions and temperature. Associated with this increase in stress, the plateau of this transformation becomes steeper. In addition, the area of the mechanical hysteresis, measured as the difference between the forces of the upper and lower plateau, increases.

  8. Articulated registration: elastic registration based on a wire-model

    Science.gov (United States)

    Martin-Fernandez, Miguel A.; Munyoz-Moreno, Emma; Martin-Fernandez, Marcos; Alberola-Lopez, Carlos

    2005-04-01

    In this paper we propose a new method of elastic registration of anatomical structures that bears an inner skeleton, such as the knee, hand or spine. Such a method has to deal with great degrees of variability, specially for the case of inter-subject registration; but even for the intra-subject case the degree of variability of images will be large since the structures we bear in mind are articulated. Rigid registration methods are clearly inappropriate for this problem, and well-known elastic methods do not usually incorporate the restriction of maintaining long skeletal structures straight. A new method is therefore needed to deal with such a situation; we call this new method "articulated registration". The inner bone skeleton is modeled with a wire model, where wires are drawn by connecting landmarks located in the main joints of the skeletal structure to be registered (long bones). The main feature of our registration method is that within the bone axis (specifically, where the wires are) an exact registration is guaranteed, while for the remaining image points an elastic registration is carried out based on a distance transform (with respect to the model wires); this causes the registration on long bones to be affine to all practical purposes, while the registration of soft tissue -- far from the bones -- is elastic. As a proof-of-concept of this method we describe the registration of hands on radiographs.

  9. FE modeling of Cu wire bond process and reliability

    NARCIS (Netherlands)

    Yuan, C.A.; Weltevreden, E.R.; Akker, P. van den; Kregting, R.; Vreugd, J. de; Zhang, G.Q.

    2011-01-01

    Copper based wire bonding technology is widely accepted by electronic packaging industry due to the world-wide cost reduction actions (compared to gold wire bond). However, the mechanical characterization of copper wire differs from the gold wire; hence the new wire bond process setting and new bond

  10. FE modeling of Cu wire bond process and reliability

    NARCIS (Netherlands)

    Yuan, C.A.; Weltevreden, E.R.; Akker, P. van den; Kregting, R.; Vreugd, J. de; Zhang, G.Q.

    2011-01-01

    Copper based wire bonding technology is widely accepted by electronic packaging industry due to the world-wide cost reduction actions (compared to gold wire bond). However, the mechanical characterization of copper wire differs from the gold wire; hence the new wire bond process setting and new bond

  11. Placement of trans-sternal wires according to an ellipsoid pressure vessel model of sternal forces.

    Science.gov (United States)

    Casha, Aaron R; Manché, Alex; Gauci, Marilyn; Camilleri-Podesta, Marie-Therese; Schembri-Wismayer, Pierre; Sant, Zdenka; Gatt, Ruben; Grima, Joseph N

    2012-03-01

    Dehiscence of median sternotomy wounds remains a clinical problem. Wall forces in thin-walled pressure vessels can be calculated by membrane stress theory. An ellipsoid pressure vessel model of sternal forces is presented together with its application for optimal wire placement in the sternum. Sternal forces were calculated by computational simulation using an ellipsoid chest wall model. Sternal forces were correlated with different sternal thicknesses and radio-density as measured by computerized tomography (CT) scans of the sternum. A comparison of alternative placement of trans-sternal wires located either at the levels of the costal cartilages or the intercostal spaces was made. The ellipsoid pressure vessel model shows that higher levels of stress are operative at increasing chest diameter (P cartilage levels when compared with adjacent intercostal spaces. This results in a decrease of average sternal stress from 438 kPa at the intercostal space level to 338 kPa at the costal cartilage level (P = 0.003). Biomechanical modelling suggests that placement of trans-sternal wires at the thicker bone and more radio-dense level of the costal cartilages will result in reduced stress.

  12. Model-Based Testability Assessment and Directed Troubleshooting of Shuttle Wiring Systems

    Science.gov (United States)

    Deb, Somnath; Domagala, Chuck; Shrestha, Roshan; Malepati, Venkatesh; Cavanaugh, Kevin; Patterson-Hine, Ann; Sanderfer, Dwight; Cockrell, Jim; Norvig, Peter (Technical Monitor)

    2000-01-01

    We have recently completed a pilot study on the Space shuttle wiring system commissioned by the Wiring Integrity Research (WIRe) team at NASA Ames Research Center, As the space shuttle ages, it is experiencing wiring degradation problems including arcing, chaffing insulation breakdown and broken conductors. A systematic and comprehensive test process is required to thoroughly test and quality assure (QA) the wiring systems. The NASA WIRe team recognized the value of a formal model based analysis for risk-assessment and fault coverage analysis. However. wiring systems are complex and involve over 50,000 wire segments. Therefore, NASA commissioned this pilot study with Qualtech Systems. Inc. (QSI) to explore means of automatically extracting high fidelity multi-signal models from wiring information database for use with QSI's Testability Engineering and Maintenance System (TEAMS) tool.

  13. Effect of microwaves on domain wall motion in thin Ni wires

    Science.gov (United States)

    Hong, Kimin; Giordano, N.

    1996-03-01

    We report new results on domain wall motion in thin (width and thickness ~ 300 ÅNi wires. The magnetoresistance exhibits discontinuities which we believe are associated with pinning and de-pinning of walls from structural defects, such as variations in the width of the sample. Upon repeated measurement, the de-pinning is found to occur over a narrow range of fields. The distribution of de-pinning fields, P(H), varies with temperature in a manner which suggests that de-pinning occurs via thermal activation at high temperatures, and quantum tunneling at low temperatures, with crossover between these two regimes at T ~ 2 - 6 K. We have also investigated the effect of a 30 GHz microwave field on P(H). In the thermal activation regime, microwaves have no effect on P(H), except through Joule heating. However, in the tunneling regime microwaves cause P(H) to split into several separate peaks. This behavior cannot be explained in terms of Joule heating, but suggests that the energy levels of a domain wall in a pinning well are quantized.

  14. Kinetic study on hot-wire-assisted atomic layer deposition of nickel thin films

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Guangjie, E-mail: ygjhzh@dpe.mm.t.u-tokyo.ac.jp; Shimizu, Hideharu; Momose, Takeshi; Shimogaki, Yukihiro [Department of Materials Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)

    2014-01-15

    High-purity Ni films were deposited using hot-wire-assisted atomic layer deposition (HW-ALD) at deposition temperatures of 175, 250, and 350 °C. Negligible amount of nitrogen or carbon contamination was detected, even though the authors used NH{sub 2} radical as the reducing agent and nickelocene as the precursor. NH{sub 2} radicals were generated by the thermal decomposition of NH{sub 3} with the assist of HW and used to reduce the adsorbed metal growth precursors. To understand and improve the deposition process, the kinetics of HW-ALD were analyzed using a Langmuir-type model. Unlike remote-plasma-enhanced atomic layer deposition, HW-ALD does not lead to plasma-induced damage. This is a significant advantage, because the authors can supply sufficient NH{sub 2} radicals to deposit high-purity metallic films by adjusting the distance between the hot wire and the substrate. NH{sub 2} radicals have a short lifetime, and it was important to use a short distance between the radical generation site and substrate. Furthermore, the impurity content of the nickel films was independent of the deposition temperature, which is evidence of the temperature-independent nature of the NH{sub 2} radical flux and the reactivity of the NH{sub 2} radicals.

  15. Overview of Wave to Wire Models

    DEFF Research Database (Denmark)

    Nielsen, Kim; Kramer, Morten Mejlhede; Ferri, Francesco

    A “Wave to Wire” (W2W) model is a numerical tool that can calculate the power output from a specified Wave Energy Converter (WEC), under specified ocean wave conditions. The tool can be used to assess and optimize the performance of a Wave Energy Converter (WEC) design and provide knowledge of th...

  16. Thermal Model of a Current-Carrying Wire in a Vacuum

    Science.gov (United States)

    Border, James

    2006-01-01

    A computer program implements a thermal model of an insulated wire carrying electric current and surrounded by a vacuum. The model includes the effects of Joule heating, conduction of heat along the wire, and radiation of heat from the outer surface of the insulation on the wire. The model takes account of the temperature dependences of the thermal and electrical properties of the wire, the emissivity of the insulation, and the possibility that not only can temperature vary along the wire but, in addition, the ends of the wire can be thermally grounded at different temperatures. The resulting second-order differential equation for the steady-state temperature as a function of position along the wire is highly nonlinear. The wire is discretized along its length, and the equation is solved numerically by use of an iterative algorithm that utilizes a multidimensional version of the Newton-Raphson method.

  17. Modelling aluminium wire bond reliability in high power OMP devices

    NARCIS (Netherlands)

    Kregting, R.; Yuan, C.A.; Xiao, A.; Bruijn, F. de

    2011-01-01

    In a RF power application such as the OMP, the wires are subjected to high current (because of the high power) and high temperature (because of the heat from IC and joule-heating from the wire itself). Moreover, the wire shape is essential to the RF performance. Hence, the aluminium wire is preferre

  18. INVESTIGATION BY NUMERICAL MODELING OF INFLUENCE OF THE SHAPE OF DEFORMING ZONE OF DIE AT WIRE DRAWING OF STEEL HIGH-CARBON WIRE ON TEMPERATURE AND MODE OF DEFORMATION IN WIRE AND DIE

    Directory of Open Access Journals (Sweden)

    Ju. L. Bobarikin

    2010-01-01

    Full Text Available Investigation by numerical modeling of influence of the form of deforming zone of die at drawing of steel highcarbon wire on temperature and strained-deformed state in wire and die is carried out.

  19. SpaceWire model development technology for satellite architecture.

    Energy Technology Data Exchange (ETDEWEB)

    Eldridge, John M.; Leemaster, Jacob Edward; Van Leeuwen, Brian P.

    2011-09-01

    Packet switched data communications networks that use distributed processing architectures have the potential to simplify the design and development of new, increasingly more sophisticated satellite payloads. In addition, the use of reconfigurable logic may reduce the amount of redundant hardware required in space-based applications without sacrificing reliability. These concepts were studied using software modeling and simulation, and the results are presented in this report. Models of the commercially available, packet switched data interconnect SpaceWire protocol were developed and used to create network simulations of data networks containing reconfigurable logic with traffic flows for timing system distribution.

  20. Durability Evaluation of a Thin Film Sensor System With Enhanced Lead Wire Attachments on SiC/SiC Ceramic Matrix Composites

    Science.gov (United States)

    Lei, Jih-Fen; Kiser, J. Douglas; Singh, Mrityunjay; Cuy, Mike; Blaha, Charles A.; Androjna, Drago

    2000-01-01

    An advanced thin film sensor system instrumented on silicon carbide (SiC) fiber reinforced SiC matrix ceramic matrix composites (SiC/SiC CMCs), was evaluated in a Mach 0.3 burner rig in order to determine its durability to monitor material/component surface temperature in harsh environments. The sensor system included thermocouples in a thin film form (5 microns thick), fine lead wires (75 microns diameter), and the bonds between these wires and the thin films. Other critical components of the overall system were the heavy, swaged lead wire cable (500 microns diameter) that contained the fine lead wires and was connected to the temperature readout, and ceramic attachments which were bonded onto the CMCs for the purpose of securing the lead wire cables, The newly developed ceramic attachment features a combination of hoops made of monolithic SiC or SiC/SiC CMC (which are joined to the test article) and high temperature ceramic cement. Two instrumented CMC panels were tested in a burner rig for a total of 40 cycles to 1150 C (2100 F). A cycle consisted of rapid heating to 1150 C (2100 F), a 5 minute hold at 1150 C (2100 F), and then cooling down to room temperature in 2 minutes. The thin film sensor systems provided repeatable temperature measurements for a maximum of 25 thermal cycles. Two of the monolithic SiC hoops debonded during the sensor fabrication process and two of the SiC/SiC CMC hoops failed during testing. The hoops filled with ceramic cement, however, showed no sign of detachment after 40 thermal cycle test. The primary failure mechanism of this sensor system was the loss of the fine lead wire-to-thin film connection, which either due to detachment of the fine lead wires from the thin film thermocouples or breakage of the fine wire.

  1. Wire-grid electromagnetic modelling of metallic cylindrical objects with arbitrary section, for Ground Penetrating Radar applications

    Science.gov (United States)

    Adabi, Saba; Pajewski, Lara

    2014-05-01

    This work deals with the electromagnetic wire-grid modelling of metallic cylindrical objects, buried in the ground or embedded in a structure, for example in a wall or in a concrete slab. Wire-grid modelling of conducting objects was introduced by Richmond in 1966 [1] and, since then, this method has been extensively used over the years to simulate arbitrarily-shaped objects and compute radiation patterns of antennas, as well as the electromagnetic field scattered by targets. For any wire-grid model, a fundamental question is the choice of the optimum wire radius and grid spacing. The most widely used criterion to fix the wire size is the so-called same-area rule [2], coming from empirical observation: the total surface area of the wires has to be equal to the surface area of the object being modelled. However, just few authors have investigated the validity of this criterion. Ludwig [3] studied the reliability of the rule by examining the canonical radiation problem of a transverse magnetic field by a circular cylinder fed with a uniform surface current, compared with a wire-grid model; he concluded that the same-area rule is optimum and that too thin wires are just as bad as too thick ones. Paknys [4] investigated the accuracy of the same-area rule for the modelling of a circular cylinder with a uniform current on it, continuing the study initiated in [3], or illuminated by a transverse magnetic monochromatic plane wave; he deduced that the same-area rule is optimal and that the field inside the cylinder is most sensitive to the wire radius than the field outside the object, so being a good error indicator. In [5], a circular cylinder was considered, embedded in a dielectric half-space and illuminated by a transverse magnetic monochromatic plane wave; the scattered near field was calculated by using the Cylindrical-Wave Approach and numerical results, obtained for different wire-grid models in the spectral domain, were compared with the exact solution. The

  2. Comparison between optical techniques and confocal microscopy for defect detection on thin wires

    Energy Technology Data Exchange (ETDEWEB)

    Siegmann, Philip; Sanchez-Brea, Luis Miguel; Martinez-Anton, Juan Carlos; Bernabeu, Eusebio

    2004-11-15

    Conventional microscopy techniques, such as atomic force microscopy (AFM), scanning electron microscopy (SEM), and confocal microscopy (CM) are not suitable for on-line surface inspection of fine metallic wires. In the recent years, some optical techniques have been developed to be used for those tasks. However, they need a rigorous validation. In this work, we have used confocal microscopy to obtain the topography z(x,y) of wires with longitudinal defects, such as dielines. The topography has been used to predict the light scattered by the wire. These simulations have been compared with experimental results, showing a good agreement.

  3. Fabricating Thin-Shell Heat-Transfer Models

    Science.gov (United States)

    Avery, D. E.; Ballard, G. K.; Wilson, M. L.; Allen, J. H., Sr.

    1985-01-01

    Freestanding shells produced for experimental aerodynamic-heating tests. Heat transfer shells require several steps and several precise molds. First, interlocking aluminum male and female molds fabricated. Holes for thermocouples drilled through male mold at desired locations. Wires having same diameter as thermocouple wire placed through holes in male mold flush to female mold. Epoxy exposed to vacuum to remove air bubbles poured between male and female molds to form thin female mold. Once mold cured, wires removed and aluminum molds separated.

  4. Current densities of thin filament MgB2/Ti/GlidCop® wire

    Science.gov (United States)

    Kováč, P.; Hušek, I.; Melišek, T.; Kopera, L.

    2011-10-01

    Fine-filamentary MgB2/Ti/GlidCop wire has been produced by an in situ process. Hydrostatic extrusion, drawing and two-axis rolling were used for wire deformation up to the size of 0.2 × 0.2 mm2. An averaged filament size of 7.6-14 µm was obtained for two-axis rolled wire and tape, which are the smallest MgB2 filaments known so far. Very short annealing periods (3-7 min) were used for the thinnest filaments, resulting in a critical current density of ≈12 000 A cm - 2 at 8 T and 4.2 K. The results presented demonstrate the ability to prepare uniform ≈10 µm size and high current density filamentary MgB2 wires in nonmagnetic sheaths, which can be applied for DC and AC coils.

  5. Thin film solar cells with Si nanocrystallites embedded in amorphous intrinsic layers by hot-wire chemical vapor deposition.

    Science.gov (United States)

    Park, Seungil; Parida, Bhaskar; Kim, Keunjoo

    2013-05-01

    We investigated the thin film growths of hydrogenated silicon by hot-wire chemical vapor deposition with different flow rates of SiH4 and H2 mixture ambient and fabricated thin film solar cells by implementing the intrinsic layers to SiC/Si heterojunction p-i-n structures. The film samples showed the different infrared absorption spectra of 2,000 and 2,100 cm(-1), which are corresponding to the chemical bonds of SiH and SiH2, respectively. The a-Si:H sample with the relatively high silane concentration provides the absorption peak of SiH bond, but the microc-Si:H sample with the relatively low silane concentration provides the absorption peak of SiH2 bond as well as SiH bond. Furthermore, the microc-Si:H sample showed the Raman spectral shift of 520 cm(-1) for crystalline phase Si bonds as well as the 480 cm(-1) for the amorphous phase Si bonds. These bonding structures are very consistent with the further analysis of the long-wavelength photoconduction tail and the formation of nanocrystalline Si structures. The microc-Si:H thin film solar cell has the photovoltaic behavior of open circuit voltage similar to crystalline silicon thin film solar cell, indicating that microc-Si:H thin film with the mixed phase of amorphous and nanocrystalline structures show the carrier transportation through the channel of nanocrystallites.

  6. De Sitter thin brane model

    Science.gov (United States)

    Nishi, Masato

    2016-07-01

    We discuss the large mass hierarchy problem in a braneworld model which represents our acceleratively expanding universe. The Randall-Sundrum (RS) model with one extra warped dimension added to a flat four-dimensional space-time cannot describe our expanding universe. Here, we study instead the de Sitter thin brane model. This is described by the same action as that for the RS model, but the four-dimensional space-time on the branes is dS_4. We study the model for both the cases of positive five-dimensional cosmological constant Λ_5 and a negative one. In the positive Λ_5 case, the four-dimensional large hierarchy necessitates a five-dimensional large hierarchy, and we cannot get a natural explanation. On the other hand, in the negative Λ_5 case, the large hierarchy is naturally realized in the five-dimensional theory in the same manner as in the RS model. Moreover, another large hierarchy between the Hubble parameter and the Planck scale is realized by the O(10^2) hierarchy of the five-dimensional quantities. Finally, we find that the lightest mass of the massive Kaluza-Klein modes and the intervals of the mass spectrum are of order 10^2 GeV, which are the same as in the RS case and do not depend on the value of the Hubble parameter.

  7. de Sitter Thin Brane Model

    CERN Document Server

    Nishi, Masato

    2015-01-01

    We discuss the large mass hierarchy problem in a braneworld model which represents our acceleratively expanding universe. The RS model with warped one extra dimension added to flat 4-dimensional space-time cannot describe our expanding universe. Here, we study instead the de Sitter thin brane model. This is described by the same action as that for the RS model, but the 4-dimensional space-time on the branes is $\\rm dS_4$. We study the model for both the cases of positive 5-dimensional cosmological constant $\\Lambda_5$ and negative one. In the positive $\\Lambda_5$ case, the 4-dimensional large hierarchy necessitates a 5-dimensional large hierarchy, and we cannot get a natural explanation. On the other hand, in the negative $\\Lambda_5$ case, the large hierarchy is naturally realized in the 5-dimensional theory in the same manner as in the RS model. Moreover, another large hierarchy between the Hubble parameter and the Planck scale is realized by the $\\cal{O}\\rm (10^2)$ hierarchy of the 5-dimensional quantities....

  8. Ultrafast deposition of silicon nitride and semiconductor silicon thin films by Hot Wire Chemical Vapor Deposition

    NARCIS (Netherlands)

    Schropp, R.E.I.; van der Werf, C.H.M.; Verlaan, V.; Rath, J.K.; Li, H. B. T.

    2009-01-01

    The technology of Hot Wire Chemical Vapor Deposition (HWCVD) or Catalytic Chemical Vapor Deposition (Cat-CVD) has made great progress during the last couple of years. This review discusses examples of significant progress. Specifically, silicon nitride deposition by HWCVD (HW-SiNx) is highlighted, a

  9. Electro-thermomechanical characterization of Ti-Ni shape memory alloy thin wires

    Directory of Open Access Journals (Sweden)

    Nascimento Maria Marony Sousa Farias

    2006-01-01

    Full Text Available The use of shape memory alloys (SMA as smart structures and other modern applications require a previous evaluation of its performance under load as well as a training procedure. In general, these requirements lead to the design and assembly of a specific test bench. In this work, an experimental set-up was specially designed to perform the electro-thermomechanical characterization of SMA wires. This apparatus was used to determine the strain-temperature (epsilon - T and electrical resistance-temperature (R - T hysteretic characteristics curves of a Ti-Ni shape memory wire (90 mm in length and 150 µm in diameter under mechanical load. The SMA wire is loaded by means of constant weights and a controlled system for injection of electrical power allows performing the heating-cooling cycles. The obtained hysteretic epsilon - T and R - T characteristics curves for some levels of applied loads are used to determine important shape memory parameters, like martensitic transformation temperatures, temperature hysteresis, temperature slopes and shape memory effect under load. These parameters were in accord with the ones found in literature for the studied SMA wires.

  10. All hot wire chemical vapor deposition low substrate temperature transparent thin film moisture barrier

    NARCIS (Netherlands)

    Spee, D.A.; Schipper, M.R.; van der Werf, C.H.M.; Rath, J.K.; Schropp, R.E.I.

    2013-01-01

    We deposited a silicon nitride/polymer hybrid multilayer moisture barrier for flexible electronics in a hot wire chemical vapor deposition process, entirely below 100 °C. We were able to reach a water vapor transmission rate (WVTR) as low as 5×10−6 g/m2/day at a temperature of 60 °C and a relative h

  11. Modelling of contact regimes in wire sawing with dissipative particle dynamics.

    Science.gov (United States)

    Bierwisch, C; Kübler, R; Kleer, G; Moseler, M

    2011-06-28

    Optimization of the wire sawing process of silicon ingots requires a profound understanding of the dynamic interaction of wire, slurry and silicon material. In this paper, the influence of wire velocity and applied wire stress on the process is investigated using dissipative particle dynamics and discrete element simulations for modelling the fluid and the grains in the abrasive suspension. In our simulations, different contact regimes occur depending on grain shape and a stress balance within the system. We observed semi-contact for high wire stress and low wire velocity and non-contact for low stress and high velocities in agreement with predictions from elasto-hydrodynamic modelling. Our simulations suggest the usage of sharp grains, since in this case, stress localization on the base of the sawing groove occurs even in the non-contact regime. These insights are likely to provide a scientific base for the optimization of sawing rates and reduction of kerf loss.

  12. On the Model Checking of the SpaceWire Link Interface

    Directory of Open Access Journals (Sweden)

    Jie Zhang

    2013-02-01

    Full Text Available In this paper we display a practical approach adopted for the formal verification of SpaceWire using model checking to solve state explosion. SpaceWire is a high-speed, full-duplex serial bus standard which is applied in aerospace, so its functions have a very high accuracy requirements. In order to prove the design of the SpaceWire was faithfully implements the SpaceWire protocol’s specification , we present our experience on the model checking of SpaceWire link interface using the Cadence SMV tool. We applied environment state machine to overcome state explosion and successfully  verified  a number of relevant properties about transmitter and controller of the SpaceWire in reasonable CPU time.  

  13. Radial electric field 3D modeling for wire arrays driving dynamic hohlraums on Z.

    Energy Technology Data Exchange (ETDEWEB)

    Mock, Raymond Cecil

    2007-06-01

    The anode-cathode structure of the Z-machine wire array results in a higher negative radial electric field (Er) on the wires near the cathode relative to the anode. The magnitude of this field has been shown to anti-correlate with the axial radiation top/bottom symmetry in the DH (Dynamic Hohlraum). Using 3D modeling, the structure of this field is revealed for different wire-array configurations and for progressive mechanical alterations, providing insight for minimizing the negative Er on the wire array in the anode-to-cathode region of the DH. Also, the 3D model is compared to Sasorov's approximation, which describes Er at the surface of the wire in terms of wire-array parameters.

  14. A thermo-electro-mechanical simulation model for hot wire cutting of EPS foam

    DEFF Research Database (Denmark)

    Petkov, Kiril; Hattel, Jesper Henri

    2016-01-01

    A one-dimensional thermo-electro-mechanical mathematical model describing the effects taking place within a Ni-Cr20% wire used in a hot-wire cutting process for free forming and rapid prototyping of expanded polystyrene (EPS) is investigated and simulated. The model implements and solves three semi...

  15. Thin-Wire Modeling Techniques Applied to Antenna Analysis.

    Science.gov (United States)

    1974-10-11

    61 Lievens, J. L... and Olson, 1. ( ., "MF Antenna System Design for Patrol Hydrofoil (Missile) (PHM)," NFLC Technical Document TD 26’), 20 August...rnnrgnni OAIA Pl/i.l’iiS^ZoCQ/ IST^NH ■^.^♦^s NP = N üüi l 001) nor. Qüib |F(NS.LT.ll «CTl««( T’JK.Hi^MBSlHL/^l ziNC^nia:(HL/ NSi 00 25...IPAL li’.FlO.*) tt tP<At«3e*BiT I".T Tɝ M Hill A^2.i)l*^ i - 00*7 00*’t G 1 Td *0 0050 VI 0051 0052 Tfi ii.iT.hi i mtJ»2.00*Al ri

  16. Force Modeling for Ultrasonic-assisted Wire Saw Cutting SiC Monocryatal Wafers

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jie; LI Shujuan; Liu Yong

    2011-01-01

    The advantages, such as a small cutting force, narrow kerf and little material waste make wire saw cut- ting suitable for machining precious materials like SiC, Si monocrystal and a variety of gem. As regards wire saw cutting fo wafer, however, in traditional wire saw cutting process, the cutting efficiency is low, the wear of wire saw is badly, the surface roughness of wafer is poor etc, which have a seriously impact on the cutting process stability and the use of wafers. Ultrasonic-assisted machining method is very suitable for processing a variety of non-conduc- tive hard and brittle materials, glass, ceramics, quartz, silicon, precious stones and diamonds, etc. In this paper, the force model of ultrusonic-assisted wire saw cutting of SiC monocrystal wafer, based on the kinematic and experi- mental analysis were established. The single factor and orthogonal experimental scheme for different processing pa- rameters such as wire saw speed, part rotation speed of and part feed rate, were carried out in traditional wire saw and ultrasonic-assisted wire saw cutting process. The multiple linear regression method is used to establish the static model among the cutting force, processing parameters and ultrasonic vibration parameters, and the model signifi- cance is verified. The results show, as regards ultrasonic-assisted wire saw cutting of SiC monicrystal wafer, both the tangential and normal cutting forces can reduce about 24. 5%-36% and 36. 6%-40%.

  17. Welding wire velocity modelling and control using an optical sensor

    DEFF Research Database (Denmark)

    Nielsen, Kirsten M.; Pedersen, Tom S.

    2007-01-01

    In this paper a method for controlling the velocity of a welding wire at the tip of the handle is described. The method is an alternative to the traditional welding apparatus control system where the wire velocity is controlled internal in the welding machine implying a poor disturbance reduction...

  18. A hybrid surface modification method on copper wire braids for enhancing thermal performance of ultra-thin heat pipes

    Science.gov (United States)

    Sheng, W. K.; Lin, H. T.; Wu, C. H.; Kuo, L. S.; Chen, P. H.

    2017-02-01

    Copper is the most widely used material in heat pipe manufacturing. Since the capability of wick structures inside a heat pipe will dominate its thermal performance, in this study, we introduce a hybrid surface modification method on the copper wire braids being inserted as wick structure into an ultra-thin heat pipe. The hybrid method is the combination of a chemical-oxidation-based method and a sol-gel method with nanoparticles being dip-coated onto the braid. The experimental data show that braids under hybrid treatment perform higher water rising speed than the oxidized braids while owning higher water net weight than those braids being only dip-coated with nanoparticle.

  19. Fast pyrolysis in a novel wire-mesh reactor: decomposition of pine wood and model compounds

    NARCIS (Netherlands)

    Hoekstra, E.; Swaaij, van W.P.M.; Kersten, S.R.A.; Hogendoorn, J.A.

    2012-01-01

    In fast pyrolysis, biomass decomposition processes are followed by vapor phase reactions. Experimental results were obtained in a unique wire-mesh reactor using pine wood, KCl impregnated pine wood and several model compounds (cellulose, xylan, lignin, levoglucosan, glucose). The wire-mesh reactor w

  20. Modeling and characterization of the sensitivity of a hot-wire particle velocity sensor

    NARCIS (Netherlands)

    Honschoten, van J.W.; Yntema, D.R.; Wiegerink, R.J.; Elwenspoek, M.

    2008-01-01

    The sensitivity of an innovative acoustic sensor composed of four hot-wires is analyzed. An analytical model is presented that describes both the air flow and the temperature distribution in and around the probe. The presence of the chip surface in the vicinity of the wires influences the acoustic f

  1. Hot-wire chemical vapor deposition of WO{sub 3−x} thin films of various oxygen contents

    Energy Technology Data Exchange (ETDEWEB)

    Houweling, Z. Silvester, E-mail: Silvester.Houweling@asml.com [Section Nanophotonics – Physics of Devices, Debye Institute for Nanomaterials Science, Utrecht University, Princetonlaan 4, 3584 CC Utrecht (Netherlands); Geus, John W. [Inorganic Chemistry and Catalysis, Utrecht University, Padualaan 8, 3584 CH Utrecht (Netherlands); Schropp, Ruud E.I. [Section Nanophotonics – Physics of Devices, Debye Institute for Nanomaterials Science, Utrecht University, Princetonlaan 4, 3584 CC Utrecht (Netherlands)

    2013-06-15

    We present the synthesis of tungsten oxide (WO{sub 3−x}) thin films consisting of layers of varying oxygen content. Configurations of layered thin films comprised of W, W/WO{sub 3−x}, WO{sub 3}/W and WO{sub 3}/W/WO{sub 3−x} are obtained in a single continuous hot-wire chemical vapor deposition process using only ambient air and hydrogen. The air oxidizes resistively heated tungsten filaments and produces the tungsten oxide species, which deposit on a substrate and are subsequently reduced by the hydrogen. The reduction of tungsten oxides to oxides of lower oxygen content (suboxides) depends on the local water vapor pressure and temperature. In this work, the substrate temperature is either below 250 °C or is kept at 750 °C. A number of films are synthesized using a combined air/hydrogen flow at various total process pressures. Rutherford backscattering spectrometry is employed to measure the number of tungsten and oxygen atoms deposited, revealing the average atomic compositions and the oxygen profiles of the films. High-resolution scanning electron microscopy is performed to measure the physical thicknesses and display the internal morphologies of the films. The chemical structure and crystallinity are investigated with Raman spectroscopy and X-ray diffraction, respectively. - Highlights: • Synthesis of tungsten oxide thin films of controllable oxygen content. • Partial reduction of WO{sub 3−x} thin films during deposition. • Deposition of layered films with configurations of W, W/WO{sub 3−x}, WO{sub 3}/W/WO{sub 3−x}. • Synthesis of WO{sub 3−x} films with atomic oxygen-to-tungsten ratios between 0.3 and 3.

  2. Water Desalination with Wires

    NARCIS (Netherlands)

    Porada, S.; Sales, B.B.; Hamelers, H.V.M.; Biesheuvel, P.M.

    2012-01-01

    We show the significant potential of water desalination using a novel capacitive wire-based technology in which anode/cathode wire pairs are constructed from coating a thin porous carbon electrode layer on top of electrically conducting rods (or wires). By alternately dipping an array of electrode

  3. Sliding mechanics of coated composite wires and the development of an engineering model for binding.

    Science.gov (United States)

    Zufall, S W; Kusy, R P

    2000-02-01

    A tribological (friction and wear) study, which was designed to simulate clinical sliding mechanics, was conducted as part of an effort to determine the suitability of poly(chloro-p-xylylene) coatings for composite orthodontic archwires. Prototype composite wires, having stiffnesses similar to those of current initial and intermediate alignment wires, were tested against stainless steel and ceramic brackets in the passive and active configurations (with and without angulation). Kinetic coefficient of friction values, which were determined to quantify sliding resistances as functions of the normal forces of ligation, had a mean that was 72% greater than uncoated wire couples at 0.43. To improve analysis of the active configuration, a mathematical model was developed that related bracket angulation, bracket width, interbracket distance, wire geometry, and wire elastic modulus to sliding resistance. From this model, kinetic coefficients of binding were determined to quantify sliding resistances as functions of the normal forces of binding. The mean binding coefficient was the same as that of uncoated wire couples at 0.42. Although penetrations through the coating were observed on many specimens, the glass-fiber reinforcement within the composite wires was undamaged for all conditions tested. This finding implies that the risk of glass fiber release during clinical use would be eliminated by the coating. In addition, the frictional and binding coefficients were still within the limits outlined by conventional orthodontic wire-bracket couples. Consequently, the coatings were regarded as an improvement to the clinical acceptability of composite orthodontic archwires.

  4. Synthesis of wo3 nanogranular thin films by hot-wire CVD

    NARCIS (Netherlands)

    Houweling, Z.S.; Geus, J.W.; Schropp, R.E.I.

    2010-01-01

    By resistively heating tungsten filaments in a constant air flow under a reduced pressure, nanogranular amorphous WO3 thin films are deposited on glassy carbon substrates. The substrate surface temperature is monitored by a thermocouple. For deposition times of 15 min and longer, the films show crys

  5. Thin Film Organic / Inorganic Multilayer Gas Barriers by Hot-Wire and Initiated CVD

    NARCIS (Netherlands)

    Spee, D.A.

    2013-01-01

    A very attractive property for many optoelectronic devices, such as solar cells and organic light emitting diodes (OLEDs), is light weight and mechanical flexibility. This will open new technological opportunities, such as thin flexible lighting, lightweight conformable solar cells, and rollable dis

  6. Structural, optical and electrical properties of ZnO/Zn 2GeO 4 porous-like thin film and wires

    Science.gov (United States)

    Jumidali, Mohd Muzafa; Sulieman, Kamal Mahir; Hashim, Md Roslan

    2011-03-01

    Zinc oxide/zinc germanium oxide (ZnO/Zn 2GeO 4) porous-like thin film and wires has been fabricated by simple thermal evaporation method at temperature about 1120 °C for 2.5 h. The structural and optical properties of the porous-like-thin film and wires have been investigated by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and photoluminescence (PL) spectroscopy. Metal semiconductor metal (MSM) photodetector structure was used to evaluate the electrical characteristics by using current-voltage ( I- V) measurements. Room temperature photoluminescence spectrum of the sample shows one prominent ultraviolet peak at 378 nm and a shoulder at 370 nm. In addition, broad visible blue emission peak at wavelength 480 nm and green emission peak at 500 nm are also observed. Strong photoelectric properties of the MSM in the UV demonstrated that the porous-like-thin film and wires contribute to its photosensitivity and therefore making ZnO/Zn 2GeO 4 wires potential photodetector in the shorter wavelength applications.

  7. Low Cycle Fatigue Evaluation of NiTi SESMA Thin Wires

    Science.gov (United States)

    Sateesh, V. L.; Senthilkumar, P.; Satisha; Dayananda, G. N.

    2014-07-01

    This paper presents experimental studies on low cycle fatigue (LCF) life of super-elastic shape memory alloy (SESMA) wires. The effect of frequency of the loading and amplitude of the strain on the fatigue life has been studied individually. Various loading frequencies have been considered to study the effect of frequency, by keeping the amplitude constant. From the experimental data, it was found that the LCF life of the SESMA reduces with increase in the frequency. The effect of amplitude on the LCF life of SESMA has also been studied, and it was found that the SESMA cycled at lower net strain has more fatigue life than the one cycled at higher net strain. Further, the plastic strain accumulation is also more in the samples tested at the higher net strain loadings. The modulus of austenite is found to be by and large independent of the frequency and amplitude of the loading. Further, martensitic unloading modulus is same for all the minimum strain amplitudes.

  8. Hydrogenated Nanocrystalline Silicon Thin Films Prepared by Hot-Wire Method with Varied Process Pressure

    Directory of Open Access Journals (Sweden)

    V. S. Waman

    2011-01-01

    Full Text Available Hydrogenated nanocrystalline silicon films were prepared by hot-wire method at low substrate temperature (200∘C without hydrogen dilution of silane (SiH4. A variety of techniques, including Raman spectroscopy, low angle X-ray diffraction (XRD, Fourier transform infrared (FTIR spectroscopy, atomic force microscopy (AFM, and UV-visible (UV-Vis spectroscopy, were used to characterize these films for structural and optical properties. Films are grown at reasonably high deposition rates (>15 Å/s, which are very much appreciated for the fabrication of cost effective devices. Different crystalline fractions (from 2.5% to 63% and crystallite size (3.6–6.0 nm can be achieved by controlling the process pressure. It is observed that with increase in process pressure, the hydrogen bonding in the films shifts from Si–H to Si–H2 and (Si–H2n complexes. The band gaps of the films are found in the range 1.83–2.11 eV, whereas the hydrogen content remains <9 at.% over the entire range of process pressure studied. The ease of depositing films with tunable band gap is useful for fabrication of tandem solar cells. A correlation between structural and optical properties has been found and discussed in detail.

  9. Model for predicting thermal conductivity using transient hot wire method

    Science.gov (United States)

    Kumar, Sublania Harish; Singh K., J.; Somani A., K.

    2016-05-01

    The use of the hot wire method for estimating the thermal conductivity measurement has recently known a significant increase. However, this method is theoretically not applicable to materials. Thermal conductivity values are necessary whenever a heat transfer problem is to be evaluated.

  10. Flow and Heat Flux Behavior of Micro-bubble Jet Flows Observed in Thin, Twisted-Wire, Subcooled Boiling in Microgravity

    Science.gov (United States)

    Munro, Troy R.; Ban, Heng

    2015-02-01

    Thin wire, subcooled boiling experiments were performed onboard an aircraft flying a parabolic trajectory to provide microgravity conditions for improved observation of jet flow phenomena and their behavior in the absence of buoyant forces. A new type of nucleation jet flow was observed in microgravity. This new micro-bubble jet flow is seen at medium to high heat fluxes and is characterized by a region of the wire that forms multiple jet columns which contain micro-bubbles. These columns flow together and penetrate tens of millimeters into the bulk fluid. Bubble behavior on the wire was observed to progress from a dominance of larger isolated bubbles on the wire to a dominance of micro-bubble jet flows on the wire as heat flux was increased. There was also a transient transition from a few large isolated bubbles to micro-bubble jet flow dominance for a set heat flux. A cross correlation calculation provided velocities of micro-bubbles in the flow, which were in the range of 4-14 mm/s. These velocities were used with convection correlations to show that fluid flows induced by jet flows are a significant contributor to the subcooled boiling heat transfer in microgravity, but are not the primary contributor. Additionally, a relative bubble area analysis approximates the direct contribution of these jet flows to the overall heat dissipation. These micro-bubble jet flows, which are only observed on thin wires (not flat surfaces), and the convection currents they induce, have the potential to allow for sustained fluid motion to occur in microgravity.

  11. Hot-wire vapor deposition of amorphous MoS{sub 2} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Papadimitropoulos, Georgios; Kontos, A.; Vasilopoulou, Maria; Kouvatsos, Dimitrios N.; Boukos, Nicolas; Davazoglou, Dimitrios [Institute of Nanoscience and Nanotechnology, NCSR ' ' Demokritos' ' , Attiki (Greece); Vourdas, Nikolaos [Technological Educational Institute of Chalkis (Greece); Gasparotto, Alberto [Department of Chemistry, Padova University (Italy); INSTM, Padova (Italy); Barreca, Davide [CNR-IENI, Padova (Italy); INSTM, Padova (Italy); Department of Chemistry, Padova University (Italy)

    2015-07-15

    Amorphous, as shown by X-ray diffraction measurements, MoS{sub 2} films (a-MoS{sub 2}) were deposited by heating a molybdenum wire at temperatures between 500 and 700 C in H{sub 2}S at 1 Torr. As shown by Scanning Electron Microscopy measurements, the morphology of samples depends significantly on the filament temperature; at low temperature samples are homogeneous and smooth, at intermediate temperatures they exhibit a granular microstructure and at high temperatures a columnar one. X-ray photoelectron spectroscopy measurements have shown S/Mo ratios in films varying between 2.5 and 1.5 dependent on filament temperature. Films also contain oxygen at atomic contents of 8 to 12%. As shown by XPS and Raman spectroscopy, at a filament temperature of 600 C films are mainly composed of MoS{sub 2} also containing oxygen at an atomic ratio of 8%. Spectroscopic ellipsometry measurements made on a-MoS{sub 2} films have shown that their band gap is of the order of 1.4 eV, slightly higher than that for the bulk crystalline material. Photoluminescence spectroscopy measurements have shown that samples exhibit a doublet of peaks at 2.8 and 3 eV blue shifted relatively to MoS{sub 2} samples composed of one or two mono-layers. The above indicate that the electronic structure of crystalline atomic-layer thick MoS{sub 2} is preserved in a-MoS{sub 2} films. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. Ground-state energy of the electron liquid in ultrathin wires.

    Science.gov (United States)

    Fogler, Michael M

    2005-02-11

    The ground-state energy and the density correlation function of the electron liquid in a thin one-dimensional wire are computed. The calculation is based on an approximate mapping of the problem with a realistic Coulomb interaction law onto exactly solvable models of mathematical physics. This approach becomes asymptotically exact in the limit of a small wire radius but remains numerically accurate even for modestly thin wires.

  13. Current Approach in Surface Plasmons for Thin Film and Wire Array Solar Cell Applications

    Directory of Open Access Journals (Sweden)

    Keya Zhou

    2015-07-01

    Full Text Available Surface plasmons, which exist along the interface of a metal and a dielectric, have been proposed as an efficient alternative method for light trapping in solar cells during the past ten years. With unique properties such as superior light scattering, optical trapping, guide mode coupling, near field concentration, and hot-electron generation, metallic nanoparticles or nanostructures can be tailored to a certain geometric design to enhance solar cell conversion efficiency and to reduce the material costs. In this article, we review current approaches on different kinds of solar cells, such as crystalline silicon (c-Si and amorphous silicon (a-Si thin film solar cells, organic solar cells, nanowire array solar cells, and single nanowire solar cells.

  14. Current Approach in Surface Plasmons for Thin Film and Wire Array Solar Cell Applications.

    Science.gov (United States)

    Zhou, Keya; Guo, Zhongyi; Liu, Shutian; Lee, Jung-Ho

    2015-07-22

    Surface plasmons, which exist along the interface of a metal and a dielectric, have been proposed as an efficient alternative method for light trapping in solar cells during the past ten years. With unique properties such as superior light scattering, optical trapping, guide mode coupling, near field concentration, and hot-electron generation, metallic nanoparticles or nanostructures can be tailored to a certain geometric design to enhance solar cell conversion efficiency and to reduce the material costs. In this article, we review current approaches on different kinds of solar cells, such as crystalline silicon (c-Si) and amorphous silicon (a-Si) thin film solar cells, organic solar cells, nanowire array solar cells, and single nanowire solar cells.

  15. A Comparison between Thin-Film Transistors Deposited by Hot-Wire Chemical Vapor Deposition and PECVD

    Directory of Open Access Journals (Sweden)

    Meysam Zarchi

    2015-03-01

    Full Text Available The effect of new growth techniques on the mobility and stability of amorphous silicon (a-Si:H thin film transistors (TFTs has been studied. It was suggested that the key parameter controlling the field-effect mobility and stability is the intrinsic stress in the a-Si:H layer. Amorphous and microcrystalline silicon films were deposited by radiofrequency plasma enhanced chemical vapor deposition (RF-PECVD and hot-wire chemical vapor deposition (HW-CVD at 100 ºC and 25 ºC. Structural properties of these films were measured by Raman Spectroscopy. Electronic properties were measured by dark conductivity, σd, and photoconductivity, σph. For amorphous silicon films deposited by RF-PECVD on PET, photosensitivity's of >105 were obtained at both 100 º C and 25 ºC. For amorphous silicon films deposited by HW-CVD, a photosensitivity of > 105 was obtained at 100 ºC. Microcrystalline silicon films deposited by HW-CVD at 95% hydrogen dilution show σph~ 10-4 Ω-1cm-1, while maintaining a photosensitivity of ~102 at both 100 ºC and 25 ºC. Microcrystalline silicon films with a large crystalline fraction (> 50% can be deposited by HW-CVD all the way down to room temperature.

  16. Low temperature deposition of polycrystalline silicon thin films on a flexible polymer substrate by hot wire chemical vapor deposition

    Science.gov (United States)

    Lee, Sang-hoon; Jung, Jae-soo; Lee, Sung-soo; Lee, Sung-bo; Hwang, Nong-moon

    2016-11-01

    For the applications such as flexible displays and solar cells, the direct deposition of crystalline silicon films on a flexible polymer substrate has been a great issue. Here, we investigated the direct deposition of polycrystalline silicon films on a polyimide film at the substrate temperature of 200 °C. The low temperature deposition of crystalline silicon on a flexible substrate has been successfully made based on two ideas. One is that the Si-Cl-H system has a retrograde solubility of silicon in the gas phase near the substrate temperature. The other is the new concept of non-classical crystallization, where films grow by the building block of nanoparticles formed in the gas phase during hot-wire chemical vapor deposition (HWCVD). The total amount of precipitation of silicon nanoparticles decreased with increasing HCl concentration. By adding HCl, the amount and the size of silicon nanoparticles were reduced remarkably, which is related with the low temperature deposition of silicon films of highly crystalline fraction with a very thin amorphous incubation layer. The dark conductivity of the intrinsic film prepared at the flow rate ratio of RHCl=[HCl]/[SiH4]=3.61 was 1.84×10-6 Scm-1 at room temperature. The Hall mobility of the n-type silicon film prepared at RHCl=3.61 was 5.72 cm2 V-1s-1. These electrical properties of silicon films are high enough and could be used in flexible electric devices.

  17. Hot Wire CVD for thin film triple junction cells and for ultrafast deposition of the SiN passivation layer on polycrystalline Si solar cells

    NARCIS (Netherlands)

    Schropp, R.E.I.; Franken, R.H.; Goldbach, H.D.; Houweling, Z.S.; Li, H. B. T.; Rath, J.K.; Schuttauf, J.A.; Stolk, R.L.; Verlaan, V.; van der Werf, C.H.M.

    2008-01-01

    We present recent progress on hot-wire deposited thin film solar cells and applications of silicon nitride. The cell efficiency reached for μc-Si:H n–i–p solar cells on textured Ag/ZnO presently is 8.5%, in line with the state-of-the-art level for μc-Si:H n–i–p's for any method of deposition. Such c

  18. Neural network modeling for dynamic pulsed GTAW process with wire filler based on MATLAB

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Double-sided weld pool shapes were determined by multiple welding parameters and wire feed parameters during pulsed GTAW with wire filler. Aiming at such a system with multiple inputs and outputs, an effective modeling method, consisting of the impulse signal design, model structure and parameter identification and verification, was developed based on MATLAB software. Then, dynamic neural network models, TDNNM (Topside dynamic neural network model) and BHDNNM (Backside width and topside height dynamic neural network model), were established to predict double-sided shape parameters of the weld pool. The characteristic relationship of the welding process was simulated and analyzed with the models.

  19. Synthesis of nanocrystalline silicon thin films using the increase of the deposition pressure in the hot-wire chemical vapour deposition technique

    Directory of Open Access Journals (Sweden)

    J.K. Rath

    2010-01-01

    Full Text Available Nanostructured thin silicon-based films have been deposited using the hot-wire chemical vapour deposition (HWCVD technique at the University of the Western Cape. A variety of techniques including optical and infrared spectroscopy, Raman scattering spectroscopy, X-rays diffraction (XRD and transmission electron microscopy (TEM have been used for characterisation of the films. The electrical measurements show that the films have good values of photoresponse, and the photocurrent remains stable after several hours of light soaking. This contribution will discuss the characteristics of the hydrogenated nanocrystalline silicon thin films deposited using increased process chamber pressure at a fixed hydrogen dilution ratio in monosilane gas.

  20. Numerical modelling of ozone production in a wire-cylinder corona discharge and comparison with a wire-plate corona discharge

    Science.gov (United States)

    Wang, Pengxiang; Chen, Junhong

    2009-02-01

    The effect of electrode configuration on ozone production in the direct-current corona discharge of dry and humid air is studied by a numerical model that combines the electron distribution in the corona plasma, plasma chemistry and transport phenomena. Two electrode configurations are considered: wire-cylinder discharge with air flowing along the wire axis and wire-plate discharge with air flowing transverse to the wire. The ozone distributions in both types of discharges are compared. For both electrode configurations, the ozone production rate is higher in the negative corona than in the positive corona and it decreases with an increase in relative humidity. More importantly, the detailed ozone distribution in the neighbourhood of the discharge wire, together with the ozone kinetics, reveals the possible difference in the ozone production from the two discharges. With the same operating conditions and sufficiently short flow residence time, the ozone production rate is nearly the same for both electrode configurations. When the flow residence time is longer than the characteristic time for homogeneous ozone destruction, the net ozone production is higher in the wire-cylinder discharge than in the wire-plate discharge due to relatively less ozone destruction.

  1. Modeling proximity-coupling in multifilamentary wires by grained Bean model

    Energy Technology Data Exchange (ETDEWEB)

    Akune, T. [Department of Electrical Engineering and Information Technology, Kyushu Sangyo University, 2-3-1 Matsukadai, 813-8503 Fukuoka (Japan)], E-mail: akune@te.kyusan-u.ac.jp; Yumoto, W.; Sakamoto, N. [Department of Electrical Engineering and Information Technology, Kyushu Sangyo University, 2-3-1 Matsukadai, 813-8503 Fukuoka (Japan)

    2008-09-15

    Proximity-currents between filaments in a multifilamentary wire show a close resemblance with the inter-grain current in a high-T{sub c} superconductor. The critical current densities of the proximity-induced superconducting matrix J{sub cm} can be estimated from measured twist-pitch dependence of magnetization and have been shown to follow the well-known scaling law of the pinning strength. In the grained Bean model, the filaments are immersed in the proximity-induced superconducting matrix. Difference of the superconducting characteristics of the filament, the matrix and the filament content factor give a variety of deformation on the AC susceptibility curves. The computed AC susceptibility curves of multifilamentary wires using the grained Bean model are favorably compared with the experimental results.

  2. Modeling proximity-coupling in multifilamentary wires by grained Bean model

    Science.gov (United States)

    Akune, T.; Yumoto, W.; Sakamoto, N.

    2008-09-01

    Proximity-currents between filaments in a multifilamentary wire show a close resemblance with the inter-grain current in a high- Tc superconductor. The critical current densities of the proximity-induced superconducting matrix Jcm can be estimated from measured twist-pitch dependence of magnetization and have been shown to follow the well-known scaling law of the pinning strength. In the grained Bean model, the filaments are immersed in the proximity-induced superconducting matrix. Difference of the superconducting characteristics of the filament, the matrix and the filament content factor give a variety of deformation on the AC susceptibility curves. The computed AC susceptibility curves of multifilamentary wires using the grained Bean model are favorably compared with the experimental results.

  3. Modelling and operation of sub-miniature constant temperature hot-wire anemometry

    Science.gov (United States)

    Samie, M.; Watmuff, J. H.; Van Buren, T.; Hutchins, N.; Marusic, I.; Hultmark, M.; Smits, A. J.

    2016-12-01

    High-Reynolds number flows are very common in technological applications and in nature, and hot-wire anemometry is the preferred method for measuring the time-series of fluctuating velocity in such flows. However, measurement of very high-Reynolds number flows requires hot-wires with higher temporal and spatial resolution than is available with conventional probes. Much effort has therefore been devoted to decreasing the size of the hot-wire probes and this has led to associated challenges with operation. It is this latter operation problem which is the focus of this paper. To this end, an existing theoretical model of constant-temperature hot-wire anemometers (Perry 1982 Hot-Wire Anemometry (New York: Oxford University Press), Watmuff 1995 Exp. Therm. Fluid Sci. 11 117-34) is applied, and its accuracy is tested for the first time by comparison to measurements using an in-house constant temperature anemometer (CTA) for both conventional 5~μ m-diameter wires and sub-miniature hot-wires. With the aid of this model, we propose modifications to the CTA design and demonstrate successful operation of the CTA with the Princeton nano-scale thermal anemometry probe (NSTAP) (Bailey et al 2010 J. Fluid Mech. 663 160-79). It is also shown that the transfer function obtained from the model can be utilized to estimate the true frequency response and cut-off frequency of a hot-wire-CTA system to the velocity fluctuations, which is essential in accurate measurements of energy spectrum and higher order statistics of turbulent flows.

  4. Modeling of effects of matrix on actuation characteristics of embedded shape memory alloy wires

    Institute of Scientific and Technical Information of China (English)

    CUI Xiao-long; ZHENG Yan-jun; CUI Li-shan

    2005-01-01

    Effects of matrix properties on the actuation characteristics of embedded shape memory alloy wires were studied. The coefficient of thermal expansion and the modulus of matrix have significant effect on the maximum recovery stress. The thermal strain rate of the SMA wires upon heating is more sensitive to the matrix properties than the stress rate does. Additional fibers embedded in the matrix have significant effect on the stress distribution between the SMA wires and the matrix, and thus affect the interface quality significantly. Fibers with negative thermal expansion coefficient are beneficial to the interface between shape memory alloy wires and the epoxy matrix. All conclusions based on the numerical modeling can find experimental supports.

  5. STUDY OF NUMERICAL MODELING OF SHAPE DEFORMING ZONE OF DIES, DURING DRAWING HIGH CARBON STEEL WIRE TO THE TEMPERATURE AND THE STRESS-STRAIN STATE IN THE WIRE AND DIE

    Directory of Open Access Journals (Sweden)

    O. L. Bobarikin

    2012-01-01

    Full Text Available Investigation by numerical modeling of influence of the form of deforming zone of die at drawing of steel high- carbon wire on temperature and strained-deformed state in wire and die is carried out.

  6. Anisotropic Heisenberg model in thin film geometry

    Energy Technology Data Exchange (ETDEWEB)

    Akıncı, Ümit

    2014-01-01

    The effect of the anisotropy in the exchange interaction on the phase diagrams and magnetization behavior of the Heisenberg thin film has been investigated with effective field formulation in a two spin cluster using the decoupling approximation. Phase diagrams and magnetization behaviors have been obtained for several different cases, by grouping the systems in accordance with, whether the surfaces/interior of the film has anisotropic exchange interaction or not. - Highlights: • Phase diagrams of the anisotropic Heisenberg model on the thin film obtained • Dependence of the critical properties on the film thickness obtained • Effect of the anisotropy on the magnetic properties obtained.

  7. Gas doping ratio effects on p-type hydrogenated nanocrystalline silicon thin films grown by hot-wire chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Luo, P.Q. [Solar Energy Institute, Department of Physics, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China)], E-mail: robt@sjtu.edu.cn; Zhou, Z.B. [Solar Energy Institute, Department of Physics, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China)], E-mail: zbzhou@sjtu.edu.cn; Chan, K.Y. [Thin Film Laboratory, Faculty of Engineering, Multimedia University, Jalan Multimedia, Cyberjaya 63100, Selangor (Malaysia); Tang, D.Y.; Cui, R.Q.; Dou, X.M. [Solar Energy Institute, Department of Physics, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China)

    2008-12-30

    Hydrogenated nanocrystalline silicon (nc-Si:H) grown by hot-wire chemical vapor deposition (HWCVD) has recently drawn significant attention in the area of thin-film large area optoelectronics due to possibility of high deposition rate. We report on the effects of diborane (B{sub 2}H{sub 6}) doping ratio on the microstructural and optoelectrical properties of the p-type nc-Si:H thin films grown by HWCVD at low substrate temperature of 200 deg. C and with high hydrogen dilution ratio of 98.8%. An attempt has been made to elucidate the boron doping mechanism of the p-type nc-Si:H thin films deposited by HWCVD and the correlation between the B{sub 2}H{sub 6} doping ratio, crystalline volume fraction, optical band gap and dark conductivity.

  8. Analysis of light propagation for a crossing of thin silicon wires using vertical tunnelling coupling with a thick optical channel waveguide

    Energy Technology Data Exchange (ETDEWEB)

    Tsarev, A V; Kolosovskii, E A [A.V. Rzhanov Institute of Semiconductor Physics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk (Russian Federation)

    2013-08-31

    Using silicon photonic wires in a silicon-on-insulator structure as an example, we examine the problem of crossings of thin, high-index-contrast channel waveguides. To ensure high optical wave transmission efficiency at as low a level of parasitic scattering as possible, we propose using a structure with vertical coupling between a thin tapered silicon waveguide and a thick polymer waveguide, separated by a thin buffer oxide layer. Numerical simulation is used to find conditions under which such a structure (3 × 90 μm in dimensions) ensures 98 % and 99 % transmission efficiency at ∼1.55 μm in 35- and 26-nm spectral ranges, respectively, for direct propagation and 99.99 % transmission in the transverse direction. The optical element in question is proposed for use in optical microchips with multiple channel waveguide crossings. (integrated optical waveguides)

  9. Flexible a-Si:H/nc-Si:H tandem thin film silicon solar cells on plastic substrates with i-layers made by hot-wire CVD

    Energy Technology Data Exchange (ETDEWEB)

    Li, Hongbo; Werf, C.H.M. van der; Rath, J.K. [Utrecht University, Faculty of Science, SID - Physics of Devices, Utrecht (Netherlands); Borreman, A. [Helianthos b.v., Arnhem (Netherlands); Schropp, Ruud E.I.

    2008-08-15

    In this letter we report the result of an a-Si:H/nc-Si:H tandem thin film silicon solar mini-module fabricated on plastic foil containing intrinsic silicon layers made by hot-wire CVD (efficiency 7.4%, monolithically series-connected, aperture area 25 cm{sup 2}). We used the Helianthos cell transfer process. The cells were first deposited on a temporary aluminum foil carrier, which allows the use of the optimal processing temperatures, and then transferred to a plastic foil. This letter reports the characteristics of the flexible solar cells obtained in this manner, and compares the results with those obtained on reference glass substrates. The research focus for implementation of the hot-wire CVD technique for the roll-to-roll process is also discussed. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  10. Modeling and fabrication of a planar thin film airflow sensor

    Science.gov (United States)

    Adamec, Richard J.; Tanner, Philip G.; Thiel, David V.

    2001-11-01

    A thin film airflow transducer based on the hot wire anemometer principle was designed using current MEMS modelling & simulation software. Flow sensors are commonly implemented with thermal isolation of the sensor from the bulk substrate mass using methods such as reverse side etching or sacrificial layers, however this paper will present a sensor relying on thermal insulation only. This insulation may be provided by layers of material exhibiting relatively poor thermal conduction characteristics such as silicon dioxide or polyimide, giving rise to a number of advantages such as removing the process of reverse side etching. Limiting fabrication to use of simple processes such as photolithography and sputtering/evaporative deposition also simplifies this design and assists in greatly increasing the compatibility with standard CMOS fabrication processes and materials. A combination of both theoretical computer modelling and physical fabrication and testing has been the approach to this research. Preliminary testing of this design has demonstrated small yet measurable temperature gradients across the device surface during steady state operation. The novel approach to this device is the investigation of pulsed operation, effectively a transient analysis that allows the thermal conduction effects of the bulk mass to be significantly reduced, leading to a significant increase of both efficiency and response time. Electro-thermo-mechanical and computational fluid dynamic analysis of the structure successfully model the thermal conduction, radiation and forced convection effects of the device during and after ohmic heating of the sensor's heating element.

  11. Thermoviscoelastic models for polyethylene thin films

    DEFF Research Database (Denmark)

    Li, Jun; Kwok, Kawai; Pellegrino, Sergio

    2016-01-01

    This paper presents a constitutive thermoviscoelastic model for thin films of linear low-density polyethylene subject to strains up to yielding. The model is based on the free volume theory of nonlinear thermoviscoelasticity, extended to orthotropic membranes. An ingredient of the present approach...... is that the experimentally inaccessible out-of-plane material properties are determined by fitting the model predictions to the measured nonlinear behavior of the film. Creep tests, uniaxial tension tests, and biaxial bubble tests are used to determine the material parameters. The model has been validated experimentally...

  12. Crystallographic Texture Difference Between Center and Sub-Surface of Thin Cold-Drawn Pearlitic Steel Wires

    Science.gov (United States)

    Zhao, Tian-Zhang; Zhang, Guang-Liang; Song, Hong-Wu; Cheng, Ming; Zhang, Shi-Hong

    2014-09-01

    The texture difference between the center and sub-surface of pearlitic steel wires, which were manufactured by continuous cold drawing, was investigated by orientation distribution function based on electron back-scattered diffraction at different drawing passes. A perfect fiber texture parallel to drawing direction develops gradually with drawing strain increasing at the wire center, while at the sub-surface, a quasi fiber texture with the orientation nearly parallel to the circumferential direction is found. This texture at the sub-surface is softer than the perfect fiber texture in tension. The reasons for this texture difference and influences on the wire's mechanical properties are discussed.

  13. A finite element model for independent wire rope core with double helical geometry subjected to axial loads

    Indian Academy of Sciences (India)

    Cengiz Erdonmez; C Erdem Imrak

    2011-12-01

    Due to the complex geometry of wires within a wire rope, it is difficult to model and analyse independent wire rope core accurately (IWRC). In this paper, a more realistic three-dimensional modelling approach and finite element analysis of wire ropes are explained. Single helical geometry is enough to model simple straight strand while IWRC has a more complex geometry by inclusion of double helical wires in outer strands. Taking the advantage of the double helical wires, three-dimensional IWRCs modelling is applied for both right regular lay and lang lay IWRCs. Wire-by-wire based results are gathered by using the proposed modelling and analysis method under various loading conditions. Illustrative examples are given for those show the accuracy and the robustness of the present FE analysis scheme with considering frictional properties and contact interactions between wires. FE analysis results are compared with the analytical and available test results and show reasonable agreement with a simpler and more practical approach.

  14. Wire frame: A reliable approach to build sealed engineering geological models

    Science.gov (United States)

    Xu, Nengxiong; Tian, Hong

    2009-08-01

    The technique of 3D geological modeling (3DGM) is an effective tool for representing complex geological objects. In order to improve the accuracy of geological models applied in numerical simulation methods such as finite elements and finite differences, we can use 3DGM as a modeling tool. To do this, however, 3DGM must provide the ability to model geological and artificial objects in a unified way, and its geological model must be seamless for mesh generation. We present the concept of a sealed engineering geological model (SEGM), and describe its topological representation. Three kinds of conditions: geometric continuity, topological consistency and geological consistency, which must be satisfied by SEGM, are discussed in detail. A new method for constructing an SEGM based on a wire frame is proposed. It includes three main components: wire frame construction, interface modification and reconstruction, and block tracing. Building a unitary wire frame, which is composed of many simple arcs and connects all interfaces seamlessly, is the key of this method. An algorithm, involving two intersections computations and partition of simple arcs, is proposed for building a wire frame. Additionally, we also propose a local iterative algorithm for computing fault traces. As an example, we build an SEGM for the dam area of a hydraulic engineering project in the HuNan province of China.

  15. Ultra-thin SiN{sub x} in superlattice via nitridation of a-Si in-situ hot wire chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Rai, Dharmendra Kumar; Solanki, Chetan Singh; Balasubramaniam, K.R., E-mail: bala.kavaipatti@gmail.com

    2014-08-28

    The fabrication of ultra-thin SiN{sub x} (< 2 nm) is a necessary step in third generation photovoltaics, memory, or light-emitting diode applications. Using the low temperature, cheap, scaleable synthesis technique of hot-wire chemical vapor deposition (HWCVD) for this purpose poses many challenges. Here, an approach of fabricating ultra thin SiN{sub x} of thickness ∼ 1.9 nm in a superlattice (SL) structure via nitridation of a-Si layers in-situ HWCVD at 250 °C is reported. Quantum well SL and quantum dot (QD) SL films are realized, wherein SiN{sub x} layers are formed by nitriding a-Si. Both these films investigated by Raman spectroscopy and high resolution transmission electron microscopy, reveal the formation of ultra-thin SiN{sub x} in a SL structure with a-Si, accompanied by sharp interfaces. In addition, annealing of the SL structures, results in QDs of crystalline Si in the a-Si layers, maintaining the SiN{sub x} layer as well as the sharp interface between the SiN{sub x} and a-Si layers of the as-deposited SL structure. - Highlights: • Ultra thin SiN{sub x} is fabricated by hot wire chemical vapor deposition. • SiN{sub x} layer of thickness ∼ 1.9 nm is formed via nitridation of a-Si layer at 250 °C. • Ultra thin SiN{sub x} layers are realized in superlattice films of quantum wells and quantum dots.

  16. Hybrid modelling of near-field coupling onto grounded wire under ultra-short duration perturbation

    Science.gov (United States)

    Ravelo, B.; Liu, Y.

    2014-10-01

    A time-frequency (TF) hybrid model (HM) for investigating the interaction between EM near-field (NF) aggression and grounded wire is addressed. The HM is based on the combination of techniques for extracting the EM NF radiated by electronic structures and the calculation of electrical disturbances across the wire due to EM coupling. The computation method is fundamentally inspired from transmission line (TL) theory under EM illumination. The methodology including flow chart interpreting the routine algorithm based on the combination of frequency and time domain approaches is featured. An experimental result showing the EM coupling between patch antenna-wire from 1.5-3.5GHz reveals the efficiency of the HM in frequency domain. The relevance of this HM was illustrated with a structure comprised of 20cm aggressor and 5cm victim I-shaped wires placed above a planar ground plane. The aggressor was excited with 40ns duration perturbation signal. After Matlab implementation of the HM, the disturbance voltages across the extremity of the victim wire were extracted. This simple and fast HM is useful for the EMC engineering during the design and fabrication phases of electrical and electronic systems.

  17. Thermal effects in a mechanical model for pseudoelastic behavior of NiTi wires

    Directory of Open Access Journals (Sweden)

    Hugo Soul

    2007-12-01

    Full Text Available A mechanical model for pseudoelastic behavior of NiTi wires is proposed with the aim to predict the behavior of Shape Memory Alloys(SMA damping wire elements in model structures. We have considered at first a simple linearwise stress-strain relationship to describe the basic isothermal behavior of the SMA members. Then, this basic model is modified in order to include the effect of the strain rate. The model is based on detailed experimental characterization performed on a Ni rich NiTi superelastic wire which included the study of the localized character of the deformation and the local heat generation associated with the stress induced martensitic transformation occurring in these alloys. Heat conduction along the wire and heat interaction with the surroundings was also considered. In that way, the resulting local temperature field around the transformation front is assessed and its effect on the progression of the transformation is evaluated. It is shown how the simple mechanical model reproduces the global mechanical behavior, including the existence of a maximum in the damping capacity with the transformation rate.

  18. Modeling inelastic phonon scattering in atomic- and molecular-wire junctions

    DEFF Research Database (Denmark)

    Paulsson, Magnus; Frederiksen, Thomas; Brandbyge, Mads

    2005-01-01

    Computationally inexpensive approximations describing electron-phonon scattering in molecular-scale conductors are derived from the nonequilibrium Green's function method. The accuracy is demonstrated with a first-principles calculation on an atomic gold wire. Quantitative agreement between...... the full nonequilibrium Green's function calculation and the newly derived expressions is obtained while simplifying the computational burden by several orders of magnitude. In addition, analytical models provide intuitive understanding of the conductance including nonequilibrium heating and provide...... a convenient way of parameterizing the physics. This is exemplified by fitting the expressions to the experimentally observed conductances through both an atomic gold wire and a hydrogen molecule....

  19. Steady-State Numerical Modeling of Size Effects in Wire Drawing

    DEFF Research Database (Denmark)

    Juul, Kristian Jørgensen; Nielsen, Kim Lau; Niordson, Christian Frithiof

    2016-01-01

    Wire drawing processes at micron scale receive increased interest as micro wires are increasingly required in micro electrical components. At the micron scale, size effects become important and have to be taken into consideration. The goal is to optimize the semi-cone angle of the tool in terms...... of drawing force. The present study employs a steady-state modelling technique that omits the transient regime, thus creating a basis for comprehensive parameter studies. The steady-state procedure is based on the streamline integration method presented by Dean and Hutchinson [1]. This approach allows...

  20. An equivalent magnetic dipoles model for quantitative damage recognition of broken wire

    Institute of Scientific and Technical Information of China (English)

    TAN Ji-wen; ZHAN Wei-xia; LI Chun-jing; WEN Yan; SHU Jie

    2005-01-01

    By simplifying saturatedly magnetized wire-rope to magnetic dipoles of the same magnetic field strength, an equivalent magnetic dipoles model is developed and the measuring principle for recognising damage of broken wire was presented. The relevant calculation formulas were also deduced. A composite solution method about nonlinear optimization was given. An example was given to illustrate the use of the equivalent magnetic dipoles method for quantitative damage recognition, and demonstrates that the result of this method is consistent with the real situation, so the method is valid and practical.

  1. Hot-wire chemical vapor deposition prepared aluminum doped p-type microcrystalline silicon carbide window layers for thin film silicon solar cells

    Science.gov (United States)

    Chen, Tao; Köhler, Florian; Heidt, Anna; Carius, Reinhard; Finger, Friedhelm

    2014-01-01

    Al-doped p-type microcrystalline silicon carbide (µc-SiC:H) thin films were deposited by hot-wire chemical vapor deposition at substrate temperatures below 400 °C. Monomethylsilane (MMS) highly diluted in hydrogen was used as the SiC source in favor of SiC deposition in a stoichiometric form. Aluminum (Al) introduced from trimethylaluminum (TMAl) was used as the p-type dopant. The material property of Al-doped p-type µc-SiC:H thin films deposited with different deposition pressure and filament temperature was investigated in this work. Such µc-SiC:H material is of mainly cubic (3C) SiC polytype. For certain conditions, like high deposition pressure and high filament temperature, additional hexagonal phase and/or stacking faults can be observed. P-type µc-SiC:H thin films with optical band gap E04 ranging from 2.0 to 2.8 eV and dark conductivity ranging from 10-5 to 0.1 S/cm can be prepared. Such transparent and conductive p-type µc-SiC:H thin films were applied in thin film silicon solar cells as the window layer, resulting in an improved quantum efficiency at wavelengths below 480 nm.

  2. Notes on TQFT Wire Models and Coherence Equations for SU(3 Triangular Cells

    Directory of Open Access Journals (Sweden)

    Robert Coquereaux

    2010-12-01

    Full Text Available After a summary of the TQFT wire model formalism we bridge the gap from Kuperberg equations for SU(3 spiders to Ocneanu coherence equations for systems of triangular cells on fusion graphs that describe modules associated with the fusion category of SU(3 at level k. We show how to solve these equations in a number of examples.

  3. Notes on TQFT wire models and coherence equations for SU(3) triangular cells

    CERN Document Server

    Coquereaux, R; Schieber, G

    2010-01-01

    After a summary of the TQFT wire model formalism we bridge the gap from Kuperberg equations for SU(3) spiders to Ocneanu coherence equations for systems of triangular cells on fusion graphs that describe modules associated with the fusion category of SU(3) at level k. We show how to solve these equations in a number of examples.

  4. Numerical Modelling of Wire-EDM for Predicting Erosion Rate of Silicon

    Science.gov (United States)

    Joshi, Kamlesh; Sharma, Gaurav; Dongre, Ganesh; Joshi, Suhas Sitaram

    2017-02-01

    Recently, a lot of work is carried out in photovoltaic industry for slicing Si ingots using non-conventional technique like wire-EDM apart from conventional techniques like inner diameter saw and multi-wire saw. It is an emerging technology in field of Si wafer slicing and has a potential to be cost efficient. It reduces the kerf-loss and produces crack-free Si wafers. In general, the process of Si wafer cutting using wire-EDM is less understood due to its complex nature. In this work, the complex phenomena like formation of plasma channel, melting and erosion of Si material has been modelled mathematically. Further, the effect of input energy parameters like current, open voltage and pulse on-time on plasma and plasma-ingot interface temperature has been studied. The model is further extended along the length of the wire to evaluate the erosion depth and rate. The effect of process parameters on erosion depth and rate was validated experimentally. The model considers variation in material removal through the `plasma flushing efficiency'.

  5. Modeling and identification of a fly-by-wire control system.

    OpenAIRE

    Fabio Luciano Demarchi

    2005-01-01

    This work investigates the system identification and modeling techniques applied to a fly-by-wire system for pitch control of a commercial jet aircraft. The objective of the work is to build a model based on system identification techniques and generic modeling of the system, therefore using the "grey box" approach. The identification data was obtained from experimental tests performed at Embraer "Iron Bird" laboratory. An overview on flight controls systems is presented, focusing on fly-by-...

  6. A novel transport based model for wire media and its application to scattering problems

    Science.gov (United States)

    Forati, Ebrahim

    Artificially engineered materials, known as metamaterials, have attracted the interest of researchers because of the potential for novel applications. Effective modeling of metamaterials is a crucial step for analyzing and synthesizing devices. In this thesis, we focus on wire medium (both isotropic and uniaxial) and validate a novel transport based model for them. Scattering problems involving wire media are computationally intensive due to the spatially dispersive nature of homogenized wire media. However, it will be shown that using the new model to solve scattering problems can simplify the calculations a great deal. For scattering problems, an integro-differential equation based on a transport formulation is proposed instead of the convolution-form integral equation that directly comes from spatial dispersion. The integro-differential equation is much faster to solve than the convolution equation form, and its effectiveness is confirmed by solving several examples in one-, two-, and three-dimensions. Both the integro-differential equation formulation and the homogenized wire medium parameters are experimentaly confirmed. To do so, several isotropic connected wire medium spheres have been fabricated using a rapid-prototyping machine, and their measured extinction cross sections are compared with simulation results. Wire parameters (period and diameter) are varied to the point where homogenization theory breaks down, which is observed in the measurements. The same process is done for three-dimensional cubical objects made of a uniaxail wire medium, and their measured results are compared with the numerical results based on the new model. The new method is extremely fast compared to brute-force numerical methods such as FDTD, and provides more physical insight (within the limits of homogenization), including the idea of a Debye length for wire media. The limits of homogenization are examined by comparing homogenization results and measurement. Then, a novel

  7. Diffusion through thin membranes: Modeling across scales

    Science.gov (United States)

    Aho, Vesa; Mattila, Keijo; Kühn, Thomas; Kekäläinen, Pekka; Pulkkinen, Otto; Minussi, Roberta Brondani; Vihinen-Ranta, Maija; Timonen, Jussi

    2016-04-01

    From macroscopic to microscopic scales it is demonstrated that diffusion through membranes can be modeled using specific boundary conditions across them. The membranes are here considered thin in comparison to the overall size of the system. In a macroscopic scale the membrane is introduced as a transmission boundary condition, which enables an effective modeling of systems that involve multiple scales. In a mesoscopic scale, a numerical lattice-Boltzmann scheme with a partial-bounceback condition at the membrane is proposed and analyzed. It is shown that this mesoscopic approach provides a consistent approximation of the transmission boundary condition. Furthermore, analysis of the mesoscopic scheme gives rise to an expression for the permeability of a thin membrane as a function of a mesoscopic transmission parameter. In a microscopic model, the mean waiting time for a passage of a particle through the membrane is in accordance with this permeability. Numerical results computed with the mesoscopic scheme are then compared successfully with analytical solutions derived in a macroscopic scale, and the membrane model introduced here is used to simulate diffusive transport between the cell nucleus and cytoplasm through the nuclear envelope in a realistic cell model based on fluorescence microscopy data. By comparing the simulated fluorophore transport to the experimental one, we determine the permeability of the nuclear envelope of HeLa cells to enhanced yellow fluorescent protein.

  8. Damping Models for Shear-Deformable Beam with Applications to Spacecraft Wiring Harness

    Science.gov (United States)

    2014-10-28

    and modified for application to Timoshenko beams. The inclusion of rotary inertia does add some frequency- dependence; however, careful selection of...behavior of wiring harnesses. The emphasis in this project will be on the extension of the shear-beam damping model to the Timoshenko beam, a beam model...approaches) are extended and modified for application to Timoshenko beams. The inclusion of rotary inertia does add some frequency-dependence

  9. Electroless-plating technique for fabricating thin-wall convective heat-transfer models

    Science.gov (United States)

    Avery, D. E.; Ballard, G. K.; Wilson, M. L.

    1984-01-01

    A technique for fabricating uniform thin-wall metallic heat-transfer models and which simulates a Shuttle thermal protection system tile is described. Two 6- by 6- by 2.5-in. tiles were fabricated to obtain local heat transfer rates. The fabrication process is not limited to any particular geometry and results in a seamless thin-wall heat-transfer model which uses a one-wire thermocouple to obtain local cold-wall heat-transfer rates. The tile is relatively fragile because of the brittle nature of the material and the structural weakness of the flat-sided configuration; however, a method was developed and used for repairing a cracked tile.

  10. Double-wire sternal closure technique in bovine animal models for total artificial heart implant.

    Science.gov (United States)

    Karimov, Jamshid H; Sunagawa, Gengo; Golding, Leonard A R; Moazami, Nader; Fukamachi, Kiyotaka

    2015-08-01

    In vivo preclinical testing of mechanical circulatory devices requires large animal models that provide reliable physiological and hemodynamic conditions by which to test the device and investigate design and development strategies. Large bovine species are commonly used for mechanical circulatory support device research. The animals used for chronic in vivo support require high-quality care and excellent surgical techniques as well as advanced methods of postoperative care. These techniques are constantly being updated and new methods are emerging.We report results of our double steel-wire closure technique in large bovine models used for Cleveland Clinic's continuous-flow total artificial heart development program. This is the first report of double-wire sternal fixation used in large bovine models.

  11. Modeling of a flexible beam actuated by shape memory alloy wires

    Science.gov (United States)

    Shu, Steven G.; Lagoudas, Dimitris C.; Hughes, Declan; Wen, John T.

    1997-06-01

    A thermomechanical model is developed to predict the structural response of a flexible beam with shape memory alloy (SMA) wire actuators. A geometrically nonlinear static analysis is first carried out to investigate the deformed shape of a flexible cantilever beam caused by an externally-attached SMA wire actuated electrically. The actuation force applied by the SMA actuator to the beam is evaluated by solving a coupled problem that combines a thermodynamic constitutive model of SMAs with the heat conduction equation in the SMA and the structural model of the beam. To calculate the temperature history of the SMA actuator for given electrical current input, the heat transfer equation is solved with the electrical resistive heating being modeled as a distributed heat source along the SMA wire. The steps in the formulation are connected together through an iterative scheme that takes into account the static equilibrium of the beam and the constitutive relation of SMAs, thus translating an electrical current history input into beam strain output. The proposed model is used to simulate the experimental results, thus demonstrating the feasibility of using SMA actuators for shape control of active flexible structural systems.

  12. Crosstalk Model and Estimation Formula for VLSI Interconnect Wires

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    We develop an interconnect crosstalk estimation model on the assumption of linearity for CMOS device. First, we analyze the terminal response of RC model on the worst condition from the S field to the time domain. The exact 3 order coefficients in S field are obtained due to the interconnect tree model. Based on this, a crosstalk peak estimation formula is presented. Unlike other crosstalk equations in the literature, this formula is only used coupled capacitance and grand capacitance as parameter. Experimental results show that, compared with the SPICE results, the estimation formulae are simple and accurate. So the model is expected to be used in such fields as layout-driven logic and high level synthesis, performance-driven floorplanning and interconnect planning.

  13. Experimental characterization of the constitutive materials of MgB2 multi-filamentary wires for the development of 3D numerical models

    Science.gov (United States)

    Escamez, Guillaume; Sirois, Frédéric; Tousignant, Maxime; Badel, Arnaud; Granger, Capucine; Tixador, Pascal; Bruzek, Christian-Éric

    2017-03-01

    Today MgB2 superconducting wires can be manufactured in long lengths at low cost, which makes this material a good candidate for large scale applications. However, because of its relatively low critical temperature (less than 40 K), it is necessary to operate MgB2 devices in a liquid or gaseous helium environment. In this context, losses in the cryogenic environment must be rigorously minimized, otherwise the use of a superconductor is not worthy. An accurate estimation of the losses at the design stage is therefore mandatory in order to allow determining the device architecture that minimizes the losses. In this paper, we present a complete a 3D finite element model of a 36-filament MgB2 wire based on the architecture of the Italian manufacturer Colombus. In order for the model to be as accurate as possible, we made a substantial effort to characterize all constitutive materials of the wire, namely the E–J characteristics of the MgB2 filaments and the electric and magnetic properties (B‑H curves) of nickel and monel, which are the two major non-superconducting components of the wire. All properties were characterized as a function of temperature and magnetic field. Limitations of the characterization and of the model are discussed, in particular the difficulty to extract the maximum relative permeability of nickel and monel from the experimental data, as well as the lack of a thin conductive layer model in the 3D finite element method, which prevents us from taking into account the resistive barriers around the MgB2 filaments in the matrix. Two examples of numerical simulations are provided to illustrate the capabilities of the model in its current state.

  14. Hybrid 2D-3D modelling of GTA welding with filler wire addition

    KAUST Repository

    Traidia, Abderrazak

    2012-07-01

    A hybrid 2D-3D model for the numerical simulation of Gas Tungsten Arc welding is proposed in this paper. It offers the possibility to predict the temperature field as well as the shape of the solidified weld joint for different operating parameters, with relatively good accuracy and reasonable computational cost. Also, an original approach to simulate the effect of immersing a cold filler wire in the weld pool is presented. The simulation results reveal two important observations. First, the weld pool depth is locally decreased in the presence of filler metal, which is due to the energy absorption by the cold feeding wire from the hot molten pool. In addition, the weld shape, maximum temperature and thermal cycles in the workpiece are relatively well predicted even when a 2D model for the arc plasma region is used. © 2012 Elsevier Ltd. All rights reserved.

  15. Modeling of inelastic transport in one-dimensional metallic atomic wires

    DEFF Research Database (Denmark)

    Frederiksen, Thomas; Brandbyge, Mads; Lorente, N

    2004-01-01

    devices. A full description of the transport properties of atomic-size conductors therefore requires a quantum mechanical treatment of both the electronic and mechanical degrees of freedom. In this paper, we study a one-dimensional tight-binding model of the conducting electrons combined with a balls......Atomic-size conductors represent the ultimate limit of miniaturization, and understanding their properties is an important problem in the fields of nanoelectronics and molecular electronics. Quantum effects become important which leads to a physical behavior fundamentally different from macroscopic......-and-springs model for the mechanical motion of the nuclei comprising the wire. We determine the vibrational modes and frequencies for the wires. The electronic Hamiltonian is expanded to lowest order in these normal modes....

  16. Pulsed laser ablation of wire-shaped target in a thin water jet: effects of plasma features and bubble dynamics on the PLAL process

    Science.gov (United States)

    Dell'Aglio, Marcella; De Giacomo, Alessandro; Kohsakowski, Sebastian; Barcikowski, Stephan; Wagener, Philipp; Santagata, Antonio

    2017-05-01

    In this paper, emission spectroscopy and fast imaging surveys during pulsed laser ablation in liquid (PLAL) for nanoparticles (NPs) production have been used, in order to provide further details about the process involved and the potentialities offered by a wire-shaped sample ablated in a flowing water jet. This kind of set-up has been explored because the laser ablation efficiency in water increases when a thin water layer and a wire-shaped target are used. In order to understand the physical processes causing the increasing ablation efficiency, both the laser-induced plasma and bubble dynamics generated in a flowing liquid jet have been analysed. The plasma parameters and the bubble behaviour in such a system have been compared with those observed in conventional PLAL experiments, where either a bulk or a wire-shaped target is immersed in bulk water. From the data presented here it is evidenced that the plasma and shockwave induced during the breakdown process can play a direct role in the ablation efficiency variation observed. With regard to the cavitation bubbles evolving near a free surface (the interface between water and air) it should be noted that these have to be treated with caution as a consequence of the strong influence played in these circumstances by the boundary of the water jet during its expansion dynamics. The effects due to the size of the liquid layer, the presence of the water/air interface, the liquid characteristics, the target shape, the plasma evolution and the bubble dynamics together with their outcomes on the NPs’ production, are presented and discussed.

  17. Interaction effects in a microscopic quantum wire model with strong spin-orbit interaction

    Science.gov (United States)

    Winkler, G. W.; Ganahl, M.; Schuricht, D.; Evertz, H. G.; Andergassen, S.

    2017-06-01

    We investigate the effect of strong interactions on the spectral properties of quantum wires with strong Rashba spin-orbit (SO) interaction in a magnetic field, using a combination of matrix product state and bosonization techniques. Quantum wires with strong Rashba SO interaction and magnetic field exhibit a partial gap in one-half of the conducting modes. Such systems have attracted wide-spread experimental and theoretical attention due to their unusual physical properties, among which are spin-dependent transport, or a topological superconducting phase when under the proximity effect of an s-wave superconductor. As a microscopic model for the quantum wire we study an extended Hubbard model with SO interaction and Zeeman field. We obtain spin resolved spectral densities from the real-time evolution of excitations, and calculate the phase diagram. We find that interactions increase the pseudo gap at k = 0 and thus also enhance the Majorana-supporting phase and stabilize the helical spin order. Furthermore, we calculate the optical conductivity and compare it with the low energy spiral Luttinger liquid result, obtained from field theoretical calculations. With interactions, the optical conductivity is dominated by an excotic excitation of a bound soliton-antisoliton pair known as a breather state. We visualize the oscillating motion of the breather state, which could provide the route to their experimental detection in e.g. cold atom experiments.

  18. Clinical and angiographic outcomes following first-in-man implantation of a novel thin-strut low-profile fixed-wire stent: The Svelte Coronary Stent Integrated Delivery System first-in-man trial

    NARCIS (Netherlands)

    R. Diletti (Roberto); H.M. Garcia-Garcia (Hector); C.V. Bourantas (Christos); R.J.M. van Geuns (Robert Jan); N.M. van Mieghem (Nicolas); P. Agostoni (Pierfrancesco); T. Muramatsu (Takashi); V. Farooq (Vasim); R. Spencer (Richard); J. de Schepper; M. Pomeranz (Mark); P.R. Stella (Pieter); P.W.J.C. Serruys (Patrick)

    2013-01-01

    textabstractAims: The Svelte Stent Integrated Delivery System (IDS) is a novel fixed-wire thin-strut cobalt-chromium stent characterised by a very low entry profile. The aim of the present study is to evaluate the safety and the feasibility of the Svelte stent IDS implantation in humans. Methods and

  19. Landau quantized dynamics and spectra for group-VI dichalcogenides, including a model quantum wire

    Directory of Open Access Journals (Sweden)

    Norman J. M. Horing

    2017-06-01

    Full Text Available This work is concerned with the derivation of the Green’s function for Landau-quantized carriers in the Group-VI dichalcogenides. In the spatially homogeneous case, the Green’s function is separated into a Peierls phase factor and a translationally invariant part which is determined in a closed form integral representation involving only elementary functions. The latter is expanded in an eigenfunction series of Laguerre polynomials. These results for the retarded Green’s function are presented in both position and momentum representations, and yet another closed form representation is derived in circular coordinates in terms of the Bessel wave function of the second kind (not to be confused with the Bessel function. The case of a quantum wire is also addressed, representing the quantum wire in terms of a model one-dimensional δ(x-potential profile. This retarded Green’s function for propagation directly along the wire is determined exactly in terms of the corresponding Green’s function for the system without the δ(x-potential, and the Landau quantized eigenenergy dispersion relation is examined. The thermodynamic Green’s function for the dichalcogenide carriers in a normal magnetic field is formulated here in terms of its spectral weight, and its solution is presented in a momentum/integral representation involving only elementary functions, which is subsequently expanded in Laguerre eigenfunctions and presented in both momentum and position representations.

  20. Landau quantized dynamics and spectra for group-VI dichalcogenides, including a model quantum wire

    Science.gov (United States)

    Horing, Norman J. M.

    2017-06-01

    This work is concerned with the derivation of the Green's function for Landau-quantized carriers in the Group-VI dichalcogenides. In the spatially homogeneous case, the Green's function is separated into a Peierls phase factor and a translationally invariant part which is determined in a closed form integral representation involving only elementary functions. The latter is expanded in an eigenfunction series of Laguerre polynomials. These results for the retarded Green's function are presented in both position and momentum representations, and yet another closed form representation is derived in circular coordinates in terms of the Bessel wave function of the second kind (not to be confused with the Bessel function). The case of a quantum wire is also addressed, representing the quantum wire in terms of a model one-dimensional δ (x ) -potential profile. This retarded Green's function for propagation directly along the wire is determined exactly in terms of the corresponding Green's function for the system without the δ (x ) -potential, and the Landau quantized eigenenergy dispersion relation is examined. The thermodynamic Green's function for the dichalcogenide carriers in a normal magnetic field is formulated here in terms of its spectral weight, and its solution is presented in a momentum/integral representation involving only elementary functions, which is subsequently expanded in Laguerre eigenfunctions and presented in both momentum and position representations.

  1. W-F STRUCTURE: A NEW ALGORITHM ON WIRE-FRAME MODELING

    Institute of Scientific and Technical Information of China (English)

    ZengGang; WangChanglu

    1996-01-01

    This paper advances a new algorithm oriented to geometry modeling(GM) by using frame model. The elemental data structure of frame model is the vertex. This algorithm provides a general and rapid method. By this way,we can link the vertices to construct the elemental frame and need not consider the topological relation among vertices which consist of the concrete entity. Then, we can combine the elemental frames to complete frame modeling by using aided-line method referring to concrete entity. We will discuss two keystones in the paper. Then we give a 3D geometry modeling example based on wire-frame model using the new algorithm.Key words CAD, computer graphics, frame model, modeling system

  2. Steady State Modelling of Three-core Wire Armoured Submarine Cables

    DEFF Research Database (Denmark)

    Baù, Matteo; Viafora, Nicola; Hansen, Chris Skovgaard

    2016-01-01

    in a comparative study with the IEC 60287 Standard, developed in terms of power losses, loss factors and cable ampacity. Despite the model limitations, the estimated loss factors are mainly in compliance with the state of the art, verifying the widely recognized conservatism of the IEC standard. Simulation results...... confirm that the wire armour stranding is not accounted for, but also suggest that the ampacity underrating might be due to other inaccuracies in the IEC modelling indications. Overall, the difference in terms of current rating between the FEM and the IEC approach is found to be voltage dependent and more...

  3. Micromagnetic modeling of domain wall motion in sub-100-nm-wide wires with individual and periodic edge defects

    Directory of Open Access Journals (Sweden)

    S. Dutta

    2015-12-01

    Full Text Available Reducing the switching energy of devices that rely on magnetic domain wall motion requires scaling the devices to widths well below 100 nm, where the nanowire line edge roughness (LER is an inherent source of domain wall pinning. We investigate the effects of periodic and isolated rectangular notches, triangular notches, changes in anisotropy, and roughness measured from images of fabricated wires, in sub-100-nm-wide nanowires with in-plane and perpendicular magnetic anisotropy using micromagnetic modeling. Pinning fields calculated for a model based on discretized images of physical wires are compared to experimental measurements. When the width of the domain wall is smaller than the notch period, the domain wall velocity is modulated as the domain wall propagates along the wire. We find that in sub-30-nm-wide wires, edge defects determine the operating threshold and domain wall dynamics.

  4. Concept modeling of tapered thin-walled tubes

    Institute of Scientific and Technical Information of China (English)

    Yu-cheng LIU; Michael L.DAY

    2009-01-01

    This paper presents a method to create concept models for the tapered thin-walled tubes using beam elements and spring elements. Developed concept tapered beam models with different taper angles and cross sections are compared with those detailed models through impact analyses. Important crash results are recorded and compared, and the relatively good agreement is achieved between these analyses. Concept modeling steps are illustrated in detail, and a general concept modeling method for such thin-walled tubes is summarized and presented.

  5. Damage Prediction Using Several Types of Macro-scale Damage Models in Different Cold Wire Production Lines

    OpenAIRE

    Cao, Trong-Son; Montmitonnet, Pierre; Bouchard, Pierre-Olivier; Bobadilla, Christian; Vachey, Christophe

    2014-01-01

    International audience; The purpose of the present paper is to show how and to what extent the introduction of refined, shear sensitive models improves on previous ones, based on triaxiality only, for the phenomenological description of ductile damage in bulk cold metal forming processes. Wire-drawing and wire rolling are taken as examples. A set of mechanical tests has been conducted: round bar tension, notched bar tension, plane strain tension, and torsion for pure shear deformation. Both c...

  6. Deposition of silicon nitride thin films by hot-wire CVD at 100 {sup o}C and 250 {sup o}C

    Energy Technology Data Exchange (ETDEWEB)

    Alpuim, P., E-mail: palpuim@fisica.uminho.p [Departamento de Fisica, Universidade do Minho, 4800-058 Guimaraes (Portugal); Goncalves, L.M. [Departamento de Electronica Industrial, Universidade do Minho, 4800-058 Guimaraes (Portugal); Marins, E.S. [Departamento de Fisica, Universidade do Minho, 4800-058 Guimaraes (Portugal); Viseu, T.M.R. [Departamento de Fisica, Universidade do Minho, 4710-057 Braga (Portugal); Ferdov, S. [Departamento de Fisica, Universidade do Minho, 4800-058 Guimaraes (Portugal); Bouree, J.E. [Laboratoire de Physique des Interfaces et des Couches Minces, CNRS UMR 7647, Ecole Polytechnique, 91128 Palaiseau (France)

    2009-04-30

    Silicon nitride thin films for use as passivation layers in solar cells and organic electronics or as gate dielectrics in thin-film transistors were deposited by the Hot-wire chemical vapor deposition technique at a high deposition rate (1-3 A/s) and at low substrate temperature. Films were deposited using NH{sub 3}/SiH{sub 4} flow rate ratios between 1 and 70 and substrate temperatures of 100 {sup o}C and 250 {sup o}C. For NH{sub 3}/SiH{sub 4} ratios between 40 and 70, highly transparent (T {approx} 90%), dense films (2.56-2.74 g/cm{sup 3}) with good dielectric properties and refractive index between 1.93 and 2.08 were deposited on glass substrates. Etch rates in BHF of 2.7 A/s and < 0.5 A/s were obtained for films deposited at 100 {sup o}C and 250 {sup o}C, respectively. Films deposited at both substrate temperatures showed electrical conductivity {approx} 10{sup -14} {Omega}{sup -1} cm{sup -1} and breakdown fields > 10 MV cm{sup -1}.

  7. Proton irradiation effects on Nb3Sn wires and thin platelets in view of High Luminosity LHC upgrade

    CERN Document Server

    Spina, Tiziana; Flükiger, René; Cerny, Radovan

    In order to estimate the lifetime of quadrupole magnets in the High-Luminosity (HL) LHC accelerator, a precise knowledge of the potential damage on the superconductors caused by the simultaneous action of several high energy irradiation sources is needed. The present work treats the effects of high energy proton irradiation on the physical properties of Nb3Sn, the superconducting material used in the quadrupoles of HL – LHC: the critical current density (Jc), the critical temperature (Tc), the upper critical field (Hc2) and finally the Bragg - Williams atomic order parameter (S) in the Nb3Sn wires in the quadrupoles. The significant variations of the critical surface induced by radiation could indeed lead to loss of performance of the superconducting magnets.

  8. Optical modeling and simulation of thin-film photovoltaic devices

    CERN Document Server

    Krc, Janez

    2013-01-01

    In wafer-based and thin-film photovoltaic (PV) devices, the management of light is a crucial aspect of optimization since trapping sunlight in active parts of PV devices is essential for efficient energy conversions. Optical modeling and simulation enable efficient analysis and optimization of the optical situation in optoelectronic and PV devices. Optical Modeling and Simulation of Thin-Film Photovoltaic Devices provides readers with a thorough guide to performing optical modeling and simulations of thin-film solar cells and PV modules. It offers insight on examples of existing optical models

  9. Canonical Statistical Model for Maximum Expected Immission of Wire Conductor in an Aperture Enclosure

    Science.gov (United States)

    Bremner, Paul G.; Vazquez, Gabriel; Christiano, Daniel J.; Trout, Dawn H.

    2016-01-01

    Prediction of the maximum expected electromagnetic pick-up of conductors inside a realistic shielding enclosure is an important canonical problem for system-level EMC design of space craft, launch vehicles, aircraft and automobiles. This paper introduces a simple statistical power balance model for prediction of the maximum expected current in a wire conductor inside an aperture enclosure. It calculates both the statistical mean and variance of the immission from the physical design parameters of the problem. Familiar probability density functions can then be used to predict the maximum expected immission for deign purposes. The statistical power balance model requires minimal EMC design information and solves orders of magnitude faster than existing numerical models, making it ultimately viable for scaled-up, full system-level modeling. Both experimental test results and full wave simulation results are used to validate the foundational model.

  10. A new approach for modeling of dark current characteristics of quantum wire infrared photodetectors

    Institute of Scientific and Technical Information of China (English)

    H. Barickaby; A. Zarifkar; M. H. Sheikhi

    2011-01-01

    In order to study the dark current characteristics in a quantum wire infrared photodetector (QRIP), the average number of electrons in quantum wires (QRs) must be got, which is mostly too complicated. In this paper we give a simple formula to calculate the average number of carriers in a quantum wire (QR) that can be easily evaluated by mathematical softwares, and then we use this formula to study dark current characteristics ora quantum wire infrared photodetector (QRIP).

  11. A Sufficient Condition for a Wire-Frame Representing a Solid Modeling Uniquely

    Institute of Scientific and Technical Information of China (English)

    WANG Jiaye; CHEN Hui; WANG Wenping

    2001-01-01

    Generally speaking, it is impossible for a wire-frame to define a 3D object uniquely. But wire-frame as a graphics medium is still applied in some industrial areas. A sufficient condition is presented in this paper. If this condition is satisfied by a wire-frame,then the wire-frame can represent a 3D object uniquely. The result is applied to manufacturing of progressive stripe.

  12. Vibrating wire alignment technique

    CERN Document Server

    Xiao-Long, Wang; lei, Wu; Chun-Hua, Li

    2013-01-01

    Vibrating wire alignment technique is a kind of method which through measuring the spatial distribution of magnetic field to do the alignment and it can achieve very high alignment accuracy. Vibrating wire alignment technique can be applied for magnet fiducialization and accelerator straight section components alignment, it is a necessary supplement for conventional alignment method. This article will systematically expound the international research achievements of vibrating wire alignment technique, including vibrating wire model analysis, system frequency calculation, wire sag calculation and the relation between wire amplitude and magnetic induction intensity. On the basis of model analysis this article will introduce the alignment method which based on magnetic field measurement and the alignment method which based on amplitude and phase measurement. Finally, some basic questions will be discussed and the solutions will be given.

  13. Simple model on collisionless thin-shell instability growth

    CERN Document Server

    Doria, Domenico; Dieckmann, Mark E

    2016-01-01

    The manuscript discusses a simple model on the Thin Shell Instability (TSI) growth phenomenon at early stage, by only imposing the fulfillment of conservation laws; and in particular just applying the laws of mass and linear momentum conservation, without taking into account the energy partitioning inside the thin shell.

  14. Three-stage Method for Identifying the Dynamic Model Parameters of Stranded Wire Helical Springs

    Institute of Scientific and Technical Information of China (English)

    ZHAO Yu; WANG Shilong; ZHOU Jie; LI Chuan; SUN Shouli

    2015-01-01

    The dynamic behavior of the stranded wire helical spring is described by a modified Bouc-Wen model while the model parameters must be identified using an identification method and experimental data. Existing identification methods usually relies either solely nonlinear iterative algorithms or manually trial and error. Therefore, the identification process can be rather time consuming and effort taking. As a result, these methods are not ideal for engineering applications. To come up with a more practical method, a three-stage identification method is proposed. Periodic loading and identification simulations are carried out to verify the effectiveness of the proposed method. Noises are added to the simulated data to test the performance of the proposed method when dealing with noise contaminated data. The simulation results indicate that the proposed method is able to give satisfying results when the noise levels are set to be 0.01, 0.03, 0.05 and 0.07. In addition, the proposed method is also applied to experimental data and compared with an existing method. The experimental data is acquired through a periodic loading test. The experiment results suggest that the proposed method features better accuracy compared with the existing method. An effective approach is proposed for identifying the model parameters of the stranded wire helical spring.

  15. Modelling of coil-loaded wire antenna using composite multiple domain basis functions

    CSIR Research Space (South Africa)

    Lysko, AA

    2010-03-01

    Full Text Available with electrically small features. The reduction in the number of unknowns is accomplished by a logical aggregation/grouping of the individual wire segments into equivalent continuous wires. A single composite basis function is applied over several wire segments...

  16. Finite element modeling of the powder-in- tube process for manufacture of BSCCO-2212 superconducting wires

    Science.gov (United States)

    Shah, R.; Tangrila, S.; Rachakonda, S.; Thirukkonda, M.

    1995-12-01

    High-temperature superconductors have recently attracted a great deal of attention owing to their potential use in a variety of applications including power generators, superconducting magnets for mine sweepers or ship propulsion motors, and magnetic levitation transportation systems. The powder-in-tube (PIT) process has emerged as one of the most promising and economically feasible techniques to produce long lengths high-Tc oxide based superconducting wires. The PIT method involves multi-pass wire drawing followed by rolling and heat treatment. This work focuses on the development of finite element models to simulate the PIT drawing process for fabrication of silver sheathed Bi-2212 superconducting wires. The numerical models were used to predict the density of the oxide powder, the wire drawing forces, and the silver-oxide ratio during drawing. A cap-type pressure dependent constitutive equation was implemented in the model to simulate the powder behavior. The model incorporated experimentally obtained material data for the silver and powder. Data from wire drawing experiments were used to verify model predictions.

  17. Distribution of wire deformation within strands of wire ropes

    Institute of Scientific and Technical Information of China (English)

    MA Jun; GE Shi-rong; ZHANG De-kun

    2008-01-01

    Using ANSYS software, we developed a modeling program for several kinds of wire ropes with metal cores and built a geometric model for the 6x19 IWS wire rope. Through proper grid partitioning, a finite element model for calculating the deformation of wire rope was obtained. Completely constraining one end of the wire rope and applying an axial force to the other end, we established the boundary conditions for solving the model. In addition, we numerically simulated the stress and deformation of the wire, obtaining the deformation distribution of each wire within the wire rope under different laying directions.At the end, a tensile test of the 6x19 IWS wire rope was carried out and the results of simulation and experiment compared.

  18. Rotational giant magnetoimpedance in soft magnetic wires: Modelization through Fourier harmonic contribution

    Science.gov (United States)

    Gómez-Polo, C.; Vázquez, M.; Knobel, M.

    2001-01-01

    A method to investigate the giant magnetoimpedance effect based on Fourier analysis is introduced. The study is carried out on a FeCoSiB amorphous wire with vanishing magnetostriction subjected to joule heating (current annealing) treatment that induces an enhancement of circumferential magnetic anisotropy and modifies the magnetoimpedance response of the samples. Experimental results are interpreted within the framework of the classical electrodynamical model, where the circumferential permeability plays the dominant role in the field dependence of the complex impedance of the sample. A rotational magnetization model is employed to determine the circular magnetization process, and a mean value of the circumferential permeability is obtained through the harmonic components obtained through Fourier analysis of the time derivative of the circular magnetization. This simple model is able to reproduce the observed experimental behavior, i.e., evolution of the field dependence of the complex impedance with annealing and the asymmetrical field dependence under a dc biased electrical current.

  19. Algorithm for Modeling Wire Cut Electrical Discharge Machine Parameters using Artificial Neural Network

    Directory of Open Access Journals (Sweden)

    G.Sankara Narayanan

    2014-03-01

    Full Text Available Unconventional machining process finds lot of application in aerospace and precision industries. It is preferred over other conventional methods because of the advent of composite and high strength to weight ratio materials, complex parts and also because of its high accuracy and precision. Usually in unconventional machine tools, trial and error method is used to fix the values of process parameters which increase the production time and material wastage. A mathematical model functionally relating process parameters and operating parameters of a wire cut electric discharge machine (WEDM is developed incorporating Artificial neural network (ANN and the work piece material is SKD11 tool steel. This is accomplished by training a feed forward neural network with back propagation learning Levenberg-Marquardt algorithm. The required data used for training and testing the ANN are obtained by conducting trial runs in wire cut electric discharge machine in a small scale industry from South India. The programs for training and testing the neural network are developed, using matlab 7.0.1 package. In this work, we have considered the parameters such as thickness, time and wear as the input values and from that the values of the process parameters are related and a algorithm is arrived. Hence, the proposed algorithm reduces the time taken by trial runs to set the input process parameters of WEDM and thus reduces the production time along with reduction in material wastage. Thus the cost of machining processes is reduced and thereby increases the overall productivity.

  20. Charge transport through biomolecular wires in a solvent: bridging molecular dynamics and model Hamiltonian approaches.

    Science.gov (United States)

    Gutiérrez, R; Caetano, R A; Woiczikowski, B P; Kubar, T; Elstner, M; Cuniberti, G

    2009-05-22

    We present a hybrid method based on a combination of classical molecular dynamics simulations, quantum-chemical calculations, and a model Hamiltonian approach to describe charge transport through biomolecular wires with variable lengths in presence of a solvent. The core of our approach consists in a mapping of the biomolecular electronic structure, as obtained from density-functional based tight-binding calculations of molecular structures along molecular dynamics trajectories, onto a low-dimensional model Hamiltonian including the coupling to a dissipative bosonic environment. The latter encodes fluctuation effects arising from the solvent and from the molecular conformational dynamics. We apply this approach to the case of pG-pC and pA-pT DNA oligomers as paradigmatic cases and show that the DNA conformational fluctuations are essential in determining and supporting charge transport.

  1. Research on Modeling and Active Steering Control Algorithm for Electric Forklift Steer-by-Wire System

    Directory of Open Access Journals (Sweden)

    Yang Liu

    2016-11-01

    Full Text Available In this paper, according to the structure characteristics of steer-by-wire (SBW system for the TFC20 electric forklift, steering dynamics model and two degree of freedom vehicle model are deduced for SBW forklift. Aiming at the free design features of the angular transmission characteristics in the SBW system of electric forklift, the theory of active steering control strategy is studied. After analyzing the influence factors of the angular trans mission ratio of the steering system, the ideal angular transmission ratio is proposed, which is based on the yaw rate gain invariance. Also, the control strategy of the yaw rate feedback and the full state feedback is studied. The simulation results show that the above strategy is effective for the active steering control; it can improve the operating stability and the response speed of the forklift.

  2. Two-dimensional model colloids and nano wires: phase transitions, effects of external potentials and quantum effects

    Science.gov (United States)

    Franzrahe, K.; Henseler, P.; Ricci, A.; Strepp, W.; Sengupta, S.; Dreher, M.; Kircher, Chr.; Lohrer, M.; Quester, W.; Binder, K.; Nielaba, P.

    2005-07-01

    Quantum effects, structures and phase transitions in Nano-systems have been analyzed. An overview is given on the results of our computations on structural and elastic properties of model colloids, on phase transitions of model colloids in external fields, and on structural and electronic properties of stretched atomic wires.

  3. Mechanical and piezoresistive properties of thin silicon films deposited by plasma-enhanced chemical vapor deposition and hot-wire chemical vapor deposition at low substrate temperatures

    Science.gov (United States)

    Gaspar, J.; Gualdino, A.; Lemke, B.; Paul, O.; Chu, V.; Conde, J. P.

    2012-07-01

    This paper reports on the mechanical and piezoresistance characterization of hydrogenated amorphous and nanocrystalline silicon thin films deposited by hot-wire chemical vapor deposition (HWCVD) and radio-frequency plasma-enhanced chemical vapor deposition (PECVD) using substrate temperatures between 100 and 250 °C. The microtensile technique is used to determine film properties such as Young's modulus, fracture strength and Weibull parameters, and linear and quadratic piezoresistance coefficients obtained at large applied stresses. The 95%-confidence interval for the elastic constant of the films characterized, 85.9 ± 0.3 GPa, does not depend significantly on the deposition method or on film structure. In contrast, mean fracture strength values range between 256 ± 8 MPa and 600 ± 32 MPa: nanocrystalline layers are slightly stronger than their amorphous counterparts and a pronounced increase in strength is observed for films deposited using HWCVD when compared to those grown by PECVD. Extracted Weibull moduli are below 10. In terms of piezoresistance, n-doped radio-frequency nanocrystalline silicon films deposited at 250 °C present longitudinal piezoresistive coefficients as large as -(2.57 ± 0.03) × 10-10 Pa-1 with marginally nonlinear response. Such values approach those of crystalline silicon and of polysilicon layers deposited at much higher temperatures.

  4. Modeling plasmonic scattering combined with thin-film optics.

    Science.gov (United States)

    Schmid, M; Klenk, R; Lux-Steiner, M Ch; Topic, M; Krc, J

    2011-01-14

    Plasmonic scattering from metal nanostructures presents a promising concept for improving the conversion efficiency of solar cells. The determination of optimal nanostructures and their position within the solar cell is crucial to boost the efficiency. Therefore we established a one-dimensional optical model combining plasmonic scattering and thin-film optics to simulate optical properties of thin-film solar cells including metal nanoparticles. Scattering models based on dipole oscillations and Mie theory are presented and their integration in thin-film semi-coherent optical descriptions is explained. A plasmonic layer is introduced in the thin-film structure to simulate scattering properties as well as parasitic absorption in the metal nanoparticles. A proof of modeling concept is given for the case of metal-island grown silver nanoparticles on glass and ZnO:Al/glass substrates. Using simulations a promising application of the nanoparticle integration is shown for the case of CuGaSe(2) solar cells.

  5. Chondronecrosis with osteomyelitis in broilers: Further defining a bacterial challenge model using the wire flooring model.

    Science.gov (United States)

    Al-Rubaye, Adnan A K; Ekesi, Nnamdi S; Zaki, Sura; Emami, Nima K; Wideman, Robert F; Rhoads, Douglas D

    2017-02-01

    Lameness in broiler chickens is a significant animal welfare and financial issue. Bacterial chondronecrosis with osteomyelitis (BCO) leading to lameness can be enhanced by rearing young broilers on wire flooring. Using the wire floor system, we identified Staphylococcus agnetis as the predominant isolate in BCO of the proximal tibiae and femora, and blood of lame broilers. Administration of S. agnetis isolates in water can induce lameness. We now report that the wire floor system increases bacterial translocation into the blood stream. We have also determined that approximately 10(5) CFU/mL is the minimum effective dose in the drinking water and that challenge at 10, 20, or 30 days of age produces similar incidences of lameness. BCO isolates of S. agnetis are much more effective than other Staphylococcus species and can overwhelm the protective effects of some commercial probiotics. Finally, we also demonstrated that the BCO lameness induced by administration of S. agnetis in the drinking water is transmissible to unchallenged broilers in the same pen. © 2016 Poultry Science Association Inc.

  6. COST-EFFECTIVE WIRE-HARNESS MODEL BY USING POLYMER OPTICAL FIBER

    Directory of Open Access Journals (Sweden)

    Mohammad Syuhaimi Ab-Rahman

    2013-01-01

    Full Text Available In the past decade automotive industries faced the exponential increase of in-vehicle electronic devices. The hydraulic systems are replacing with sophisticate electronic systems. Market demands for exploiting new in-vehicle technologies such as multimedia systems, internet access, GPS, Mobile communication, internal private network; engine, body and power train intelligent control and monitoring systems are increasing daily. These new needs make the wire-harness as physical pathway for power and data more complex. The amount of different data types’ transmission in vehicle networking requires higher bandwidth and subsequently applying expensive and advanced equipment. Also more functions and facilities lead to raise the number of Electronic Control Units (ECU. The high cost of manufacturing and implementing all mentioned equipment and systems only can be justified to luxury vehicle’s high prices. This study presents a conceptual model of in-vehicle networking which would lead to apply considerable portion of these advanced systems in non-luxury vehicles. In this context, Polymer Optical Fibers (POF exploited to achieve high speed bandwidth and cost-effective solution to transfer huge amount of data and one ECU to control and manage body/cabin electronic devices. Regarding to technical specification of POFs and using visible light as data carrier, they can meet all new needs of implementing modern expected technologies for non-luxury cars at inexpensive solution. In addition, POFs are easy-to-use, reliable and flexible in compare with silica base optical fibers. This study suggests three red, blue and green lights for transferring video/audio, communication data network such as internet/vehicle internal network and body/cabin command lines respectively. Moreover, this concept model claims for reducing wire-harness with integration of command lines into multiplexed POF line. By command lines integration also it is possible to merge

  7. Characteristics of heat transfer fouling of thin stillage using model thin stillage and evaporator concentrates

    Science.gov (United States)

    Challa, Ravi Kumar

    The US fuel ethanol demand was 50.3 billion liters (13.3 billion gallons) in 2012. Corn ethanol was produced primarily by dry grind process. Heat transfer equipment fouling occurs during corn ethanol production and increases the operating expenses of ethanol plants. Following ethanol distillation, unfermentables are centrifuged to separate solids as wet grains and liquid fraction as thin stillage. Evaporator fouling occurs during thin stillage concentration to syrup and decreases evaporator performance. Evaporators need to be shutdown to clean the deposits from the evaporator surfaces. Scheduled and unscheduled evaporator shutdowns decrease process throughput and results in production losses. This research were aimed at investigating thin stillage fouling characteristics using an annular probe at conditions similar to an evaporator in a corn ethanol production plant. Fouling characteristics of commercial thin stillage and model thin stillage were studied as a function of bulk fluid temperature and heat transfer surface temperature. Experiments were conducted by circulating thin stillage or carbohydrate mixtures in a loop through the test section which consisted of an annular fouling probe while maintaining a constant heat flux by electrical heating and fluid flow rate. The change in fouling resistance with time was measured. Fouling curves obtained for thin stillage and concentrated thin stillage were linear with time but no induction periods were observed. Fouling rates for concentrated thin stillage were higher compared to commercial thin stillage due to the increase in solid concentration. Fouling rates for oil skimmed and unskimmed concentrated thin stillage were similar but lower than concentrated thin stillage at 10% solids concentration. Addition of post fermentation corn oil to commercial thin stillage at 0.5% increments increased the fouling rates up to 1% concentration but decreased at 1.5%. As thin stillage is composed of carbohydrates, protein, lipid

  8. Wire Chamber

    CERN Multimedia

    Magnetoscriptive readout wire chamber. Multi-wire detectors contain layers of positively and negatively charged wires enclosed in a chamber full of gas. A charged particle passing through the chamber knocks negatively charged electrons out of atoms in the gas, leaving behind positive ions. The electrons are pulled towards the positively charged wires. They collide with other atoms on the way, producing an avalanche of electrons and ions. The movement of these electrons and ions induces an electric pulse in the wires which is collected by fast electronics. The size of the pulse is proportional to the energy loss of the original particle.

  9. wire chamber

    CERN Multimedia

    1967-01-01

    Magnetoscriptive readout wire chamber.Multi-wire detectors contain layers of positively and negatively charged wires enclosed in a chamber full of gas. A charged particle passing through the chamber knocks negatively charged electrons out of atoms in the gas, leaving behind positive ions. The electrons are pulled towards the positively charged wires. They collide with other atoms on the way, producing an avalanche of electrons and ions. The movement of these electrons and ions induces an electric pulse in the wires which is collected by fast electronics. The size of the pulse is proportional to the energy loss of the original particle.

  10. DEVELOPMENT OF 2D HUMAN BODY MODELING USING THINNING ALGORITHM

    Directory of Open Access Journals (Sweden)

    K. Srinivasan

    2010-11-01

    Full Text Available Monitoring the behavior and activities of people in Video surveillance has gained more applications in Computer vision. This paper proposes a new approach to model the human body in 2D view for the activity analysis using Thinning algorithm. The first step of this work is Background subtraction which is achieved by the frame differencing algorithm. Thinning algorithm has been used to find the skeleton of the human body. After thinning, the thirteen feature points like terminating points, intersecting points, shoulder, elbow, and knee points have been extracted. Here, this research work attempts to represent the body model in three different ways such as Stick figure model, Patch model and Rectangle body model. The activities of humans have been analyzed with the help of 2D model for the pre-defined poses from the monocular video data. Finally, the time consumption and efficiency of our proposed algorithm have been evaluated.

  11. wire chamber

    CERN Multimedia

    Proportional multi-wire chamber. Multi-wire detectors contain layers of positively and negatively charged wires enclosed in a chamber full of gas. A charged particle passing through the chamber knocks negatively charged electrons out of atoms in the gas, leaving behind positive ions. The electrons are pulled towards the positively charged wires. They collide with other atoms on the way, producing an avalanche of electrons and ions. The movement of these electrons and ions induces an electric pulse in the wires which is collected by fast electronics. The size of the pulse is proportional to the energy loss of the original particle. Proportional wire chambers allow a much quicker reading than the optical or magnetoscriptive readout wire chambers.

  12. Mathematical Model of Quasi-state Temperature Distribution of Hot-Wire during Hot-Wire TIG Welding Process%热丝TIG焊热丝准稳态温度场的解析模型

    Institute of Scientific and Technical Information of China (English)

    赵福海; 华学明; 叶欣舢; 吴毅雄

    2012-01-01

    Based on the law of the conservation of energy and Fouriers law, the mathematical models re-spectively considering the effect of resistance heat and the heat transferred through the weld pool on the hot-wire temperature distribution were developed. And then based on the superposition principle the math- ematical model of quasi-state temperature distribution of ,hot-wire heated by resistance energy was devel- oped. The accuracy of the mathematical model was validated by comparing the result of calculating from the mathematical model with the experimental result from the literature. The impact of current density, wire feeding speed, wire extension on temperature distribution of hot-wire was elaborately discussed. The results show that the mathematical model has high accuracy to effectively analyze the process of wire heat-ed by resistance energy. The larger the current density or wire extension is, the higher the temperature in different positions on the wire extension is, however, the bigger the wire feeding speed is, the higher the pre-heating temperature is. In some certain cases, the matching relations among current density, wire feeding speed and wire extension can be concluded.%基于能量守恒和傅里叶定律,建立了电阻加热和熔池传热对热丝温度分布影响的数学模型;基于叠加原理建立了电阻加热热丝钨极惰性气体(TIG)焊热丝准稳态温度分布的数学解析模型,并验证了其计算结果;讨论了热丝电流密度、送丝速度以及焊丝干伸长等因素对焊丝温度分布的影响规律.结果表明:该数学模型具有很高的精确性,可用于热丝加热过程的分析.焊丝电流密度越大,焊丝各位置温度越高;送丝速度越大,焊丝各点的温度越低;焊丝干伸长越大,焊丝端部的预热温度越高.得到了一定条件下焊丝电流密度、送丝速度和焊丝干伸长三者之间的数值匹配关系.

  13. Coupled wire model of symmetric Majorana surfaces of topological superconductors II: 32-fold periodic topological orders

    Science.gov (United States)

    Zhang, Zhao; Sahoo, Sharmistha; Teo, Jeffrey

    We mimic the massless surface Majorana's of topological superconductors by coupled wire models in two spatial dimensions, and introduce many-body gapping interactions that preserve time reversal symmetry. Coupling with a Z2 gauge theory, the symmetric gapped surface generically carries a non-trivial GN topological order, where N is the number of Majorana species and GN is some SO(r)1 or SO(3)3 -like topological state. These form a 32-fold periodic class GN ≅GN + 32 , and a Z32 relative tensor product structure GN1⊗bGN2 ≅GN1 +N2 by anyon condensation. We present the anyon structures of these topological states, and understand the topological orders through bulk-boundary correspondence and the Wilson structures on a torus geometry.

  14. Particle Capture Efficiency in a Multi-Wire Model for High Gradient Magnetic Separation

    CERN Document Server

    Eisenträger, Almut; Griffiths, Ian M

    2014-01-01

    High gradient magnetic separation (HGMS) is an efficient way to remove magnetic and paramagnetic particles, such as heavy metals, from waste water. As the suspension flows through a magnetized filter mesh, high magnetic gradients around the wires attract and capture the particles, removing them from the fluid. We model such a system by considering the motion of a paramagnetic tracer particle through a periodic array of magnetized cylinders. We show that there is a critical Mason number (ratio of viscous to magnetic forces) below which the particle is captured irrespective of its initial position in the array. Above this threshold, particle capture is only partially successful and depends on the particle's entry position. We determine the relationship between the critical Mason number and the system geometry using numerical and asymptotic calculations. If a capture efficiency below 100% is sufficient, our results demonstrate how operating the HGMS system above the critical Mason number but with multiple separa...

  15. Numerical Modelling of Electric Conductance of a thin Sheet

    Directory of Open Access Journals (Sweden)

    Mojmir Kollar

    2006-01-01

    Full Text Available In this paper the numeric modelling of total resistance of a thin sheet, with local conductivity in randomlydistributed grains higher then is that of the basic matrix, is presented. The 2D model is formed by a structure of longitudinaland transversal conductors interconnected in nodes of a square net. In all nodes, using iteration procedure, the potential isdetermined from which the conductance of sheet is computed between two touching electrodes. The described model can beused to imitate the behaviour of heterogeneous thin conducting sheets prepared by different techniques. The model wasverified in some cases where the net resistance is well known from the theory.

  16. Thinning factor distributions viewed through numerical models of continental extension

    Science.gov (United States)

    Svartman Dias, Anna Eliza; Hayman, Nicholas W.; Lavier, Luc L.

    2016-12-01

    A long-standing question surrounding rifted margins concerns how the observed fault-restored extension in the upper crust is usually less than that calculated from subsidence models or from crustal thickness estimates, the so-called "extension discrepancy." Here we revisit this issue drawing on recently completed numerical results. We extract thinning profiles from four end-member geodynamic model rifts with varying width and asymmetry and propose tectonic models that best explain those results. We then relate the spatial and temporal evolution of upper to lower crustal thinning, or crustal depth-dependent thinning (DDT), and crustal thinning to mantle thinning, or lithospheric DDT, which are difficult to achieve in natural systems due to the lack of observations that constrain thinning at different stages between prerift extension and lithospheric breakup. Our results support the hypothesis that crustal DDT cannot be the main cause of the extension discrepancy, which may be overestimated because of the difficulty in recognizing distributed deformation, and polyphase and detachment faulting in seismic data. More importantly, the results support that lithospheric DDT is likely to dominate at specific stages of rift evolution because crustal and mantle thinning distributions are not always spatially coincident and at times are not even balanced by an equal magnitude of thinning in two dimensions. Moreover, either pure or simple shear models can apply at various points of time and space depending on the type of rift. Both DDT and pure/simple shear variations across space and time can result in observed complex fault geometries, uplift/subsidence, and thermal histories.

  17. H2-norm for mesh optimization with application to electro-thermal modeling of an electric wire in automotive context

    Science.gov (United States)

    Chevrié, Mathieu; Farges, Christophe; Sabatier, Jocelyn; Guillemard, Franck; Pradere, Laetitia

    2017-04-01

    In automotive application field, reducing electric conductors dimensions is significant to decrease the embedded mass and the manufacturing costs. It is thus essential to develop tools to optimize the wire diameter according to thermal constraints and protection algorithms to maintain a high level of safety. In order to develop such tools and algorithms, accurate electro-thermal models of electric wires are required. However, thermal equation solutions lead to implicit fractional transfer functions involving an exponential that cannot be embedded in a car calculator. This paper thus proposes an integer order transfer function approximation methodology based on a spatial discretization for this class of fractional transfer functions. Moreover, the H2-norm is used to minimize approximation error. Accuracy of the proposed approach is confirmed with measured data on a 1.5 mm2 wire implemented in a dedicated test bench.

  18. Modeling and finite element analysis of rod and wire steel rolling process

    Institute of Scientific and Technical Information of China (English)

    Shulun Liao; Liwen Zhang; Siyu Yuan; Yu Zhen; Shuqi Guo

    2008-01-01

    Two thermomechanical coupled elastic-plastic finite element (FE) models were developed for predicting the 12-pass continuous rolling process of GCr15 rod and wire steel. The distances between stands in the proposed models were set according to the actual values, and the billets were shortened in the models to reduce the calculation time. To keep the continuity of simulation, a technique was developed to transfer temperature data between the meshes of different models in terms of nodal parameters by interpolation functions. The different process variables related to the rolling process, such as temperature, total equivalent plastic strain,equivalent plastic strain rate, and contact friction force, were analyzed. Also, the proposed models were applied to analyze the reason for the occurrence of an excessive spread in width. Meanwhile, it was also utilized to assess the influence of the roll diameter change on the simulated results such as temperature and rolling force. The simulated results of temperature are found to agree well with the measured results.

  19. Thermo-Electrical Mathematical Model for Prediction of Ni-Cr Hot-Wire Temperature in Free Air and Inside Small Circular Cavities

    DEFF Research Database (Denmark)

    Petkov, Kiril; Hattel, Jesper Henri

    2017-01-01

    is a semicoupled solution of the heat conduction equation and the electrical diffusion equation in a one-dimensional (1-D) control volume finite-difference framework. A study on the available natural convection correlations for thin metal wires for Rayleigh numbers in the range of 10-3-101 is carried out in order...

  20. Wire Array Photovoltaics

    Science.gov (United States)

    Turner-Evans, Dan

    arrays. These devices offer potential efficiencies of 34%, as demonstrated through an analytical model and optoelectronic simulations. SiGe and Ge wires were fabricated via chemical-vapor deposition and reactive ion etching. GaAs was then grown on these substrates at the National Renewable Energy Lab and yielded ns lifetime components, as required for achieving high efficiency devices.

  1. Steady-state numerical modeling of size effects in micron scale wire drawing

    DEFF Research Database (Denmark)

    Juul, Kristian Jørgensen; Nielsen, Kim Lau; Niordson, Christian Frithiof

    2017-01-01

    Wire drawing processes at the micron scale have received increased interest as micro wires are increasingly required in electrical components. It is well-established that size effects due to large strain gradient effects play an important role at this scale and the present study aims to quantify...... these effects for the wire drawing process. Focus will be on investigating the impact of size effects on the most favourable tool geometry (in terms of minimizing the drawing force) for various conditions between the wire/tool interface. The numerical analysis is based on a steady-state framework that enables...... convergence without dealing with the transient regime, but still fully accounts for the history dependence as-well as the elastic unloading. Thus, it forms the basis for a comprehensive parameter study. During the deformation process in wire drawing, large plastic strain gradients evolve in the contact region...

  2. Electromagnetic Nondestructive Evaluation of Wire Insulation and Models of Insulation Material Properties

    Science.gov (United States)

    Bowler, Nicola; Kessler, Michael R.; Li, Li; Hondred, Peter R.; Chen, Tianming

    2012-01-01

    Polymers have been widely used as wiring electrical insulation materials in space/air-craft. The dielectric properties of insulation polymers can change over time, however, due to various aging processes such as exposure to heat, humidity and mechanical stress. Therefore, the study of polymers used in electrical insulation of wiring is important to the aerospace industry due to potential loss of life and aircraft in the event of an electrical fire caused by breakdown of wiring insulation. Part of this research is focused on studying the mechanisms of various environmental aging process of the polymers used in electrical wiring insulation and the ways in which their dielectric properties change as the material is subject to the aging processes. The other part of the project is to determine the feasibility of a new capacitive nondestructive testing method to indicate degradation in the wiring insulation, by measuring its permittivity.

  3. FINITE ELEMENT MODELING OF THIN CIRCULAR SANDWICH PLATES DEFLECTION

    Directory of Open Access Journals (Sweden)

    K. S. Kurachka

    2014-01-01

    Full Text Available A mathematical model of a thin circular sandwich plate being under the vertical load is proposed. The model employs the finite element method and takes advantage of an axisymmetric finite element that leads to the small dimension of the resulting stiffness matrix and sufficient accuracy for practical calculations. The analytical expressions for computing local stiffness matrices are found, which can significantly speed up the process of forming the global stiffness matrix and increase the accuracy of calculations. A software is under development and verification. The discrepancy between the results of the mathematical model and those of analytical formulas for homogeneous thin circularsandwich plates does not exceed 7%.

  4. Online optimized hysteresis-based steering feel model for steer-by-wire systems

    Directory of Open Access Journals (Sweden)

    Ahmet Kirli

    2016-06-01

    Full Text Available In rubber-wheeled road vehicles, the mechanical connection between steering wheel and front wheels provides steering-related feedback to the driver. The torque fed back to the driver through the steering linkages and steering wheel, which is called steering feel, helps the driver in controlling the vehicle. The torque feedback is reproduced via artificial methods in steer-by-wire systems due to the lack of mechanical connection. In this work, in order to minimize the physical workload and the lateral acceleration under the consideration of handling performance, optimization of a hysteresis-based steering feel has been studied. A 2-degree-of-freedom bicycle model based on the magic formula tire model has been used for simulations and hardware-in-the-loop experiments. A mathematical model is proposed in order to create an adaptive model-based optimization of the hysteresis parameters simultaneously while driving. A hardware-in-the-loop experimental setup has been used for the driving tests. The weave and the double-lane change tests have been performed with different drivers in order to demonstrate and quantify the optimization methods that are presented in this work.

  5. NUMERICAL MODELING AND INVESTIGATION OF CONTACT FRICTION INFLUENCE ON THERMAL FIELDS DISTRIBUTION AND DEFLECTED MODE IN STEEL WIRE AT HIGH-SPEED WIRE DRAWING

    Directory of Open Access Journals (Sweden)

    M. N. Vereshchagin

    2009-01-01

    Full Text Available The appraisal of  character of  the temperature fields distribution in dies at their interactions in the processes of  wire drawing in dependence on contact friction in conditions of  the system wire-die is given.

  6. A model for pressurized hydrogen induced thin film blisters

    NARCIS (Netherlands)

    van den Bos, R.A.J.M.; Reshetniak, V.; Lee, Christopher James; Benschop, Jozef Petrus Henricus; Bijkerk, Frederik

    2016-01-01

    We introduce a model for hydrogen induced blister formation in nanometer thick thin films. The model assumes that molecular hydrogen gets trapped under a circular blister cap causing it to deflect elastically outward until a stable blister is formed. In the first part, the energy balance required

  7. A model for pressurized hydrogen induced thin film blisters

    NARCIS (Netherlands)

    Bos, van den R.A.J.M.; Reshetniak, V.; Lee, C.J.; Benschop, J.P.H.; Bijkerk, F.

    2016-01-01

    We introduce a model for hydrogen induced blister formation in nanometer thick thin films. The model assumes that molecular hydrogen gets trapped under a circular blister cap causing it to deflect elastically outward until a stable blister is formed. In the first part, the energy balance required fo

  8. A scattering model for surface-textured thin films

    NARCIS (Netherlands)

    Jäger, K.; Zeman, M.

    2009-01-01

    We present a mathematical model that relates the surface morphology of randomly surface-textured thin films with the intensity distribution of scattered light. The model is based on the first order Born approximation [see e.g., M. Born and E. Wolf, Principles of Optics, 7th ed. (Cambridge University

  9. A scattering model for surface-textured thin films

    NARCIS (Netherlands)

    Jäger, K.; Zeman, M.

    2009-01-01

    We present a mathematical model that relates the surface morphology of randomly surface-textured thin films with the intensity distribution of scattered light. The model is based on the first order Born approximation [see e.g., M. Born and E. Wolf, Principles of Optics, 7th ed. (Cambridge University

  10. wire chamber

    CERN Multimedia

    Multi-wire detectors contain layers of positively and negatively charged wires enclosed in a chamber full of gas. A charged particle passing through the chamber knocks negatively charged electrons out of atoms in the gas, leaving behind positive ions. The electrons are pulled towards the positively charged wires. They collide with other atoms on the way, producing an avalanche of electrons and ions. The movement of these electrons and ions induces an electric pulse in the wires which is collected by fast electronics. The size of the pulse is proportional to the energy loss of the original particle.

  11. wire chamber

    CERN Multimedia

    Was used in ISR (Intersecting Storage Ring) split field magnet experiment. Multi-wire detectors contain layers of positively and negatively charged wires enclosed in a chamber full of gas. A charged particle passing through the chamber knocks negatively charged electrons out of atoms in the gas, leaving behind positive ions. The electrons are pulled towards the positively charged wires. They collide with other atoms on the way, producing an avalanche of electrons and ions. The movement of these electrons and ions induces an electric pulse in the wires which is collected by fast electronics. The size of the pulse is proportional to the energy loss of the original particle.

  12. Wire chamber

    CERN Multimedia

    Multi-wire detectors contain layers of positively and negatively charged wires enclosed in a chamber full of gas. A charged particle passing through the chamber knocks negatively charged electrons out of atoms in the gas, leaving behind positive ions. The electrons are pulled towards the positively charged wires. They collide with other atoms on the way, producing an avalanche of electrons and ions. The movement of these electrons and ions induces an electric pulse in the wires which is collected by fast electronics. The size of the pulse is proportional to the energy loss of the original particle.

  13. wire chamber

    CERN Multimedia

    1985-01-01

    Multi-wire detectors contain layers of positively and negatively charged wires enclosed in a chamber full of gas. A charged particle passing through the chamber knocks negatively charged electrons out of atoms in the gas, leaving behind positive ions. The electrons are pulled towards the positively charged wires. They collide with other atoms on the way, producing an avalanche of electrons and ions. The movement of these electrons and ions induces an electric pulse in the wires which is collected by fast electronics. The size of the pulse is proportional to the energy loss of the original particle.

  14. Understanding nanoparticle formation by a wire explosion process through experimental and modelling studies

    Science.gov (United States)

    Sindhu, T. K.; Sarathi, R.; Chakravarthy, S. R.

    2008-01-01

    A wire explosion process (WEP) has been used to produce nano aluminium powder in nitrogen, argon and helium atmospheres. The impact of energy deposited into the exploding conductor on the size and shape of the particles was analysed using TEM analysis, which forms the first part of the study. It is observed that the higher the energy deposited, the smaller the particles formed. In the second part, modelling studies were carried out by solving the general dynamic equation through the nodal approach, and the particle size distributions were predicted. It is realized that, at the point of high saturation ratio and nucleation rate, the size of the critical nucleus formed is low. The particle size distribution predicted by the model correlates well with the experimental results. Time-series analysis of particle formation indicates that particles of lower dimensions form and, in the process of coagulation, larger particles are formed. It is realized that the plasma formed during the explosion plays a major role in the particle formation, and the modelling studies confirm that particle formation is not an instantaneous process but requires a certain time period to form stable sizes and shapes.

  15. Modelling on c-Si/a-Si:H wire solar cells: some key parameters to optimize the photovoltaic performance

    Directory of Open Access Journals (Sweden)

    Alvarez J.

    2012-07-01

    Full Text Available Solar cells based on silicon nano- or micro-wires have attracted much attention as a promising path for low cost photovoltaic technology. The key point of this structure is the decoupling of the light absorption from the carriers collection. In order to predict and optimize the performance potential of p- (or n- doped c-Si/ n-(or p- doped a-Si:H nanowire-based solar cells, we have used the Silvaco-Atlas software to model a single-wire device. In particular, we have noticed a drastic decrease of the open-circuit voltage (Voc when increasing the doping density of the silicon core beyond an optimum value. We present here a detailed study of the parameters that can alter the Voc of c-Si(p/a-Si:H (n wires according to the doping density in c-Si. A comparison with simulation results obtained on planar c-Si/a-Si:H heterojunctions shows that the drop in Voc, linked to an increase of the dark current in both structures, is more pronounced for radial junctions due to geometric criteria. These numerical modelling results have lead to a better understanding of transport phenomena within the wire.

  16. Modeling of hydrogen effect on the superelastic behavior of Ni-Ti shape memory alloy wires

    Science.gov (United States)

    Lachiguer, Amani; Bouby, Céline; Gamaoun, Fehmi; Bouraoui, Tarak; Ben Zineb, Tarak

    2016-11-01

    Superelastic NiTi wires are widely used in orthodontic treatments, but sometimes fracture can be observed after few months of use in buccal cavity and attributed to the degradation of NiTi mechanical properties due to hydrogen absorption. In this paper, a modeling approach is proposed in order to describe the effect of hydrogen diffusion on the transformation properties of NiTi SMAs. In order to experimentally predict such effects, cathodic hydrogen charging was performed at a current density of 10 A/{m}2 for 6h, 24h, 48h and 72h in 0.9% NaCl aqueous solution at room temperature. Tensile tests were carried out shortly after hydrogen charging. The obtained stress-strain curves showed an increase of yield transformation stresses for forward and reverse martensitic transformations and a decrease of maximum transformation strain. Using Fick’s second law, the transformation temperatures variation can be expressed as a function of the mean concentration of absorbed hydrogen and then taked into account in the SMA constitutive model developed by Chemisky et al (2011). The numerical results are compared to the experimental ones to calibrate the proposed method. Simulations showed that hydrogen diffusion induces a shifting of transfomation temperatures, a decreasing of maximum transformation strain and an increasing of yield transfomation stresses.

  17. New mouse model of skeletal muscle atrophy using spiral wire immobilization.

    Science.gov (United States)

    Onda, Akiko; Kono, Hajime; Jiao, Qibin; Akimoto, Takayuki; Miyamoto, Toshikazu; Sawada, Yasuhiro; Suzuki, Katsuhiko; Kusakari, Yoichiro; Minamisawa, Susumu; Fukubayashi, Toru

    2016-10-01

    Disuse-induced skeletal muscle atrophy is a serious concern; however, there is not an effective mouse model to elucidate the molecular mechanisms. We developed a noninvasive atrophy model in mice. After the ankle joints of mice were bandaged into a bilateral plantar flexed position, either bilateral or unilateral hindlimbs were immobilized by wrapping in bonsai steel wire. After 3, 5, or 10 days of immobilization of the hip, knee, and ankle, the weight of the soleus and plantaris muscles decreased significantly in both bilateral and unilateral immobilization. MAFbx/atrogin-1 and MuRF1 mRNA was found to have significantly increased in both muscles, consistent with disuse-induced atrophy. Notably, the procedure did not result in either edema or necrosis in the fixed hindlimbs. This method allows repeated, direct access to the immobilized muscle, making it a useful procedure for concurrent application and assessment of various therapeutic interventions. Muscle Nerve 54: 788-791, 2016. © 2016 Wiley Periodicals, Inc.

  18. Wire and extended ladder model predict THz oscillations in DNA monomers, dimers and trimers

    CERN Document Server

    Lambropoulos, K; Morphis, A; Tassi, M; Lopp, R; Georgiadis, G; Theodorakou, M; Chatzieleftheriou, M; Simserides, C

    2016-01-01

    We call \\textit{monomer} a B-DNA base pair and study, analytically and numerically, electron or hole oscillations in \\textit{monomers}, \\textit{dimers} and \\textit{trimers}. We employ two Tight Binding (TB) approaches: (I) at the base-pair level, using the on-site energies of the base pairs and the hopping parameters between successive base pairs i.e. \\textit{a wire model}, and (II) at the single-base level, using the on-site energies of the bases and the hopping parameters between neighbouring bases, specifically between (a) two successive bases in the same strand, (b) complementary bases that define a base pair, and (c) diagonally located bases of successive base pairs, i.e. \\textit{an extended ladder model} since it also includes the diagonal hoppings (c). For \\textit{monomers}, with TB II, we predict periodic carrier oscillations with frequency $f \\approx$ 50-550 THz. For \\textit{dimers}, with TB I, we predict periodic carrier oscillations with $f \\approx$ 0.25-100 THz. For \\textit{trimers made of identic...

  19. Thin-Layer Drying Characteristics and Modeling of Chinese Jujubes

    Directory of Open Access Journals (Sweden)

    Xiao-Kang Yi

    2012-01-01

    Full Text Available A mathematical modeling of thin-layer drying of jujubes in a convective dryer was established under controlled conditions of temperature and velocity. The drying process took place both in the accelerating rate and falling rate period. We observed that higher temperature reduced the drying time, indicating higher drying rates of jujubes. The experimental drying data of jujubes were used to fit ten different thin-layer models, then drying rate constants and coefficients of models tested were determined by nonlinear regression analysis using the Statistical Computer Program. As for all the drying models, the Weibull distribution model was superior and best predicted the experimental values. Therefore, this model can be used to facilitate dryer design and promote efficient dryer operation by simulation and optimization of the drying processes. The volumetric shrinkable coefficient of jujubes decreased as the drying air temperature increased.

  20. Modeling of heat transfer processes in Ni{sub 2}MnIn magnetic wires

    Energy Technology Data Exchange (ETDEWEB)

    Pavlukhina, Oksana; Buchelnikov, Vasiliy [Chelyabinsk State University (Russian Federation); Sokolovskiy, Vladimir [Chelyabinsk State University (Russian Federation); National University of Science and Technology ' ' MISiS' ' , Moscow (Russian Federation)

    2016-02-15

    In this work, we study a heat transfer in the three-dimensional magnetic cooling cell involving microwires of NiMnIn Heusler alloy. Thermophysical properties of microwires such as the heat capacity, magnetic part of entropy, and magnetocaloric effect were investigated by means of Monte Carlo simulations with parameters taken from ab initio calculations as input. The diameter of the magnetic wires was varied from 10 to 50 m while the length was fixed to 1 mm. The system is supplied a coolant water flow at a constant speed and temperature. We have shown that the cooling power depends on the magnetic wire thickness and the coolant flow rate. The relaxation times of the temperature of wires, the temperature distribution in the magnetic wires and coolant, as well as the velocity fields of a coolant in the cell were calculated. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  1. Modelling driver behaviour in the case of failures in a steer-by-wire system

    NARCIS (Netherlands)

    Hogema, J.; Wewerinke, P.H.

    2010-01-01

    In dit artikel wordt een bestuurdersmodel gepresenteerd dat weergeeft hoe een bestuurder reagerrtt op systeemfouten in een steer-by-wire tuursysteem. Calibratie en validatie vond plaats aan de hand van data van een rijsimulator experiment

  2. A model for pressurized hydrogen induced thin film blisters

    OpenAIRE

    Bos, R. A. J. M. van den; Reshetniak, V.; Lee, C. J.; Benschop1, J; Bijkerk, F

    2016-01-01

    We introduce a model for hydrogen induced blister formation in nanometer thick thin films. The model assumes that molecular hydrogen gets trapped under a circular blister cap causing it to deflect elastically outward until a stable blister is formed. In the first part, the energy balance required for a stable blister is calculated. From this model, the adhesion energy of the blister cap, the internal pressure and the critical H-dose for blister formation can be calculated. In the second part,...

  3. A dynamic rheological model for thin-film lubrication

    Institute of Scientific and Technical Information of China (English)

    Zhang Xiang-Jun; Huang Ying; Guo Yan-Bao; Tian Yu; Meng Yong-Gang

    2013-01-01

    In this study,the effects of the non-Newtonian rheological properties of the lubricant in a thin-film lubrication regime between smooth surfaces were investigated.The thin-film lubrication regime typically appears in Stribeck curves with a clearly observable minimum coefficient of friction (COF) and a low-COF region,which is desired for its lower energy dissipation.A dynamic rheology of the lubricant from the hydrodynamic lubrication regime to the thin-film lubrication regime was proposed based on the convected Maxwell constitutive equation.This rheology model includes the increased relaxation time and the yield stress of the confined lubricant thin film,as well as their dependences on the lubricant film thickness.The Deborah number (De number) was adopted to describe the liquid-solid transition of the confined lubricant thin film under shearing.Then a series of Stribeck curves were calculated based on Tichy's extended lubrication equations with a perturbation of the De number.The results show that the minimum COF points in the Stribeck curve correspond to a critical De number of 1.0,indicating a liquid-to-solid transition of the confined lubricant film.Furthermore,the two proposed parameters in the dynamic rheological model,namely negative slipping length b (indicating the lubricant interfacial effect) and the characteristic relaxation time λ0,were found to determine the minimum COF and the width of the low-COF region,both of which were required to optimize the shape of the Stribeck curve.The developed dynamic rheological model interprets the correlation between the rheological and interfacial properties of lubricant and its lubrication behavior in the thin-film regime.

  4. Thin stillage fractionation using ultrafiltration: resistance in series model.

    Science.gov (United States)

    Arora, Amit; Dien, Bruce S; Belyea, Ronald L; Wang, Ping; Singh, Vijay; Tumbleson, M E; Rausch, Kent D

    2009-02-01

    The corn based dry grind process is the most widely used method in the US for fuel ethanol production. Fermentation of corn to ethanol produces whole stillage after ethanol is removed by distillation. It is centrifuged to separate thin stillage from wet grains. Thin stillage contains 5-10% solids. To concentrate solids of thin stillage, it requires evaporation of large amounts of water and maintenance of evaporators. Evaporator maintenance requires excess evaporator capacity at the facility, increasing capital expenses, requiring plant slowdowns or shut downs and results in revenue losses. Membrane filtration is one method that could lead to improved value of thin stillage and may offer an alternative to evaporation. Fractionation of thin stillage using ultrafiltration was conducted to evaluate membranes as an alternative to evaporators in the ethanol industry. Two regenerated cellulose membranes with molecular weight cut offs of 10 and 100 kDa were evaluated. Total solids (suspended and soluble) contents recovered through membrane separation process were similar to those from commercial evaporators. Permeate flux decline of thin stillage using a resistance in series model was determined. Each of the four components of total resistance was evaluated experimentally. Effects of operating variables such as transmembrane pressure and temperature on permeate flux rate and resistances were determined and optimum conditions for maximum flux rates were evaluated. Model equations were developed to evaluate the resistance components that are responsible for fouling and to predict total flux decline with respect to time. Modeling results were in agreement with experimental results (R(2) > 0.98).

  5. A hysteresis model for an orthogonal thin-film magnetometer

    NARCIS (Netherlands)

    Ridder, de René M.; Fluitman, Jan H.

    1990-01-01

    The operation of a ferromagnetic thin-film magnetometer using the anisotropic magnetoresistance effect in a permalloy film is discussed. Measurements showed the presence of a hysteresis effect not predicted by available models. It is shown that the sensitivity of the magnetometer is predicted by app

  6. High hydrogen loading of thin palladium wires through alkaline earth carbonates' precipitation on the cathodic surface - evidence of a new phase in the Pd-H system

    Energy Technology Data Exchange (ETDEWEB)

    Celani, F.; Spallone, A.; Di Gioacchino, D. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati, Frascati, RM (Italy); Marini, P.; Di Stefano, V.; Nakamura, M. [EURESYS, Rome (Italy); Pace, S. [Salerno Univ., Salerno (Italy). Dept. of Physics, Istituto Nazionale per la Fisica della Materia; Mancini, A. [ORIM S.r.l., Piediripa, MC (Italy); Tripodi, P. [Stanford Research Institut International, Stanford, CA (United States)

    2000-07-01

    A new protocol for the electrolytic loading of hydrogen (H) in thin palladium (Pd) wires has been developed. In order to increase the cathodic overvoltage, which is known to be the main parameter capable to enhance the electrolytic H loading of Pd, the catalytic action of the Pd surface versus H-H recombination has been strongly reduced by precipitation of a thin layer of alkaline-earth carbonates on the cathode. A set of electrolytes has been employed, containing small amounts of hydrochloric or sulfuric acid and strontium or calcium ions. The H loading has been continuously evaluated through ac measurements of the Pd wire resistance. Uncommonly low resistivity values, leading to an estimate of exceptionally high H loading, have been observed. Evidence of the existence of a new phase in the very high H content region of the Pd-H system has been inferred on the basis of the determination of the temperature coefficient of the electrical resistivity. Mainly for this purpose a thin layer of Hg was galvanically deposed on the cathodic surface, in order to prevent any H deloading during the measurements. The results have been fully reproduced in other 2 well equipped and experienced Laboratories (Italy, USA).

  7. Particle capture efficiency in a multi-wire model for high gradient magnetic separation

    KAUST Repository

    Eisenträger, Almut

    2014-07-21

    High gradient magnetic separation (HGMS) is an efficient way to remove magnetic and paramagnetic particles, such as heavy metals, from waste water. As the suspension flows through a magnetized filter mesh, high magnetic gradients around the wires attract and capture the particles removing them from the fluid. We model such a system by considering the motion of a paramagnetic tracer particle through a periodic array of magnetized cylinders. We show that there is a critical Mason number (ratio of viscous to magnetic forces) below which the particle is captured irrespective of its initial position in the array. Above this threshold, particle capture is only partially successful and depends on the particle\\'s entry position. We determine the relationship between the critical Mason number and the system geometry using numerical and asymptotic calculations. If a capture efficiency below 100% is sufficient, our results demonstrate how operating the HGMS system above the critical Mason number but with multiple separation cycles may increase efficiency. © 2014 AIP Publishing LLC.

  8. Giant magnetoimpedance modelling using Fourier analysis in soft magnetic amorphous wires

    Science.gov (United States)

    Gómez-Polo, C.; Knobel, M.; Pirota, K. R.; Vázquez, M.

    2001-06-01

    In this work, the Fourier analysis is employed to investigate the giant magnetoimpedance (GMI) effect in a FeCoSiB amorphous wire with vanishing magnetostriction. In order to modify the initial quenched-in anisotropy, pieces 8 cm in length were submitted to Joule heating treatments below the corresponding Curie point. The induced circumferential anisotropy determines the field evolution of the electrical impedance of the sample upon the application of an axial magnetic field. The experimental results are interpreted within the framework of the classical electrodynamical theory, where a simple rotational model is used to estimate the circular magnetization process of the sample. The mean value of the circumferential permeability is obtained through Fourier analysis of the time derivative of the estimated circular magnetization. Moreover, the existence of a second harmonic component of the GMI voltage is also experimentally detected. Its amplitude sensitively evolves with the axial DC magnetic field and its appearance is associated to an asymmetry in the circular magnetization process.

  9. 薄板烘丝工艺参数对卷烟焦油释放量的影响%The influence of bake thin wire process parameter on tobacco tar delivery

    Institute of Scientific and Technical Information of China (English)

    罗军; 赵科文; 王强春; 刘舒畅; 李皓; 侯鹏娟; 张峻松

    2016-01-01

    By designing different single-factor test,the influence of five process parameters of cylinder wall tem-perature,temperature of hot air,opening of hot air valve,moisture discharge valve,and revolving-speed of casing cylinder on the cigarette tar delivery were investigated.Through the establishment of a uniform design quadratic regression model of drying leaves set of samples and the corresponding parameters between tar deliv-ery,according to the theoretical model,optimal bake thin wire process parameters of cut tobacco leave samples were obtained:the cylinder wall temperature was 1 35 ℃,air temperature was 1 30 ℃,opening of hot air valve was 1 00%,moisture discharge valve was 50%,revolving-speed of casing cylinder was 8 r/min.%通过设计不同的单因素试验,分别考察了筒壁温度、热风温度、热风风门开度、排潮风门开度和滚筒转速5个薄板烘丝工艺参数对卷烟焦油释放量的影响.通过均匀试验设计,建立了叶组样品烘丝工艺参数与对应焦油释放量之间的二次回归模型,根据模型得到叶组样品的理论最优烘丝工艺参数:筒壁温度135℃,热风温度 130℃,热风风门开度100%,排潮风门开度50%,滚筒转速8 r/min.

  10. Computer program for Thin Wire Antennas Mounted on a Satellite Body Modeled by Flat Plates.

    Science.gov (United States)

    1978-12-01

    S \\ l I ’ ( ’ ) + t ’ p ’ )~~~ T f.~~~’ l * \\ , ]~~~ - - ( , ’ ) - 4 - lf r , , . I , t . ~~) 4 i5~ ‘~Tt ;t ~) Il5 ’-~ t~) i-~c- = L~ 1I’ .~ 4

  11. Computational modeling of muscular thin films for cardiac repair

    Science.gov (United States)

    Böl, Markus; Reese, Stefanie; Parker, Kevin Kit; Kuhl, Ellen

    2009-03-01

    Motivated by recent success in growing biohybrid material from engineered tissues on synthetic polymer films, we derive a computational simulation tool for muscular thin films in cardiac repair. In this model, the polydimethylsiloxane base layer is simulated in terms of microscopically motivated tetrahedral elements. Their behavior is characterized through a volumetric contribution and a chain contribution that explicitly accounts for the polymeric microstructure of networks of long chain molecules. Neonatal rat ventricular cardiomyocytes cultured on these polymeric films are modeled with actively contracting truss elements located on top of the sheet. The force stretch response of these trusses is motivated by the cardiomyocyte force generated during active contraction as suggested by the filament sliding theory. In contrast to existing phenomenological models, all material parameters of this novel model have a clear biophyisical interpretation. The predictive features of the model will be demonstrated through the simulation of muscular thin films. First, the set of parameters will be fitted for one particular experiment documented in the literature. This parameter set is then used to validate the model for various different experiments. Last, we give an outlook of how the proposed simulation tool could be used to virtually predict the response of multi-layered muscular thin films. These three-dimensional constructs show a tremendous regenerative potential in repair of damaged cardiac tissue. The ability to understand, tune and optimize their structural response is thus of great interest in cardiovascular tissue engineering.

  12. Treatment of patients with acromioclavicular joint injuries(Rockwood II-VI) with modeled Kirschner wire and cortical screw

    Institute of Scientific and Technical Information of China (English)

    Ivan; Viktorovich; Borozda; Mikhail; Anatolievich; Danilov; Kirill; Sergeevich; Golokhvast

    2015-01-01

    Objective: To propose an original method of surgical treatment for the acromial extremity of the clavicle rupture(Rockwood II-VI) with modeled Kirschner wire and cortical screw. Methods: Anatomical study and a test method were applied to 43 cadavers of both sexes. During the period between 2000 and 2013, 34 patients of both sexes were operated upon using the new method. In the comparison group(n = 120), the fixation of the acromial extremity of the clavicle rupture was performed with hamate plate, Lee hook and Kirschner wires.Results: Its application allows, according to the evaluation scale of Constant and Murley(1987), 10% more preservation of the function of the shoulder compared with traditional methods of surgical treatment, and shortens the required hospital treatment and temporary disability periods.Conclusions: It is shown that the proposed author’s method combines low invasiveness, minimum dimensions of the construction and low-cost treatment.

  13. Treatment of patients with acromioclavicular joint injuries (Rockwood II-VI) with modeled Kirschner wire and cortical screw

    Institute of Scientific and Technical Information of China (English)

    Ivan Viktorovich Borozda; Mikhail Anatolievich Danilov; Kirill Sergeevich Golokhvast

    2015-01-01

    Objective:To propose an original method of surgical treatment for the acromial extremity of the clavicle rupture (Rockwood II-VI) with modeled Kirschner wire and cortical screw. Methods:Anatomical study and a test method were applied to 43 cadavers of both sexes. During the period between 2000 and 2013, 34 patients of both sexes were operated upon using the new method. In the comparison group (n=120), the fixation of the acromial extremity of the clavicle rupture was performed with hamate plate, Lee hook and Kirschner wires. Results:Its application allows, according to the evaluation scale of Constant and Murley (1987), 10%more preservation of the function of the shoulder compared with traditional methods of surgical treatment, and shortens the required hospital treatment and temporary disability periods. Conclusions: It is shown that the proposed author’s method combines low invasiveness, minimum dimensions of the construction and low-cost treatment.

  14. Analysis of heat transfer from single wires close to walls

    Science.gov (United States)

    Shi, J.-M.; Gerlach, D.; Breuer, M.; Durst, F.; Lange, C. F.

    2003-04-01

    Two-dimensional numerical investigations of the forced heat convection from a microcylinder in laminar cross-flow, both in free stream and in near-wall flow, were carried out aiming at a better understanding of the physics behind the wall effects on hot-wire near-wall measurements. In the physical model, an infinitely thin plate with the same properties as the fluid (air) was used as an artificial wall. The conjugate heat transfer between the flow regions on both sides of the plate was taken into account. The effect of the conjugate thermal conditions (temperature distribution and diffusive heat flux) at the interface of the two flow regions on the heat transfer from the wire was investigated by varying the flow conditions on the side opposite to the wire location. Careful energy balance analysis was performed for both the free-stream case and the near-wall case. This enabled the authors to verify their own understanding of the physical mechanism responsible for the wall effect on hot-wire measurements and to examine other mechanisms proposed in the literature. The numerical results showed that the heat diffusion from the wire is significantly enhanced in the case of small wire-to-wall distances (Y+convection) was shown not to be the most important influencing factor for the heat transfer of a hot wire. Although the present model study was performed for a laminar flow, the results obtained are applicable to hot-wire measurements in turbulent flows, as stated in the literature.

  15. Thin Shell Model for NIF capsule stagnation studies

    Science.gov (United States)

    Hammer, J. H.; Buchoff, M.; Brandon, S.; Field, J. E.; Gaffney, J.; Kritcher, A.; Nora, R. C.; Peterson, J. L.; Spears, B.; Springer, P. T.

    2015-11-01

    We adapt the thin shell model of Ott et al. to asymmetric ICF capsule implosions on NIF. Through much of an implosion, the shell aspect ratio is large so the thin shell approximation is well satisfied. Asymmetric pressure drive is applied using an analytic form for ablation pressure as a function of the x-ray flux, as well as time-dependent 3D drive asymmetry from hohlraum calculations. Since deviations from a sphere are small through peak velocity, we linearize the equations, decompose them by spherical harmonics and solve ODE's for the coefficients. The model gives the shell position, velocity and areal mass variations at the time of peak velocity, near 250 microns radius. The variables are used to initialize 3D rad-hydro calculations with the HYDRA and ARES codes. At link time the cold fuel shell and ablator are each characterized by a density, adiabat and mass. The thickness, position and velocity of each point are taken from the thin shell model. The interior of the shell is filled with a uniform gas density and temperature consistent with the 3/2PV energy found from 1D rad-hydro calculations. 3D linked simulations compare favorably with integrated simulations of the entire implosion. Through generating synthetic diagnostic data, the model offers a method for quickly testing hypothetical sources of asymmetry and comparing with experiment. Prepared by LLNL under Contract DE-AC52-07NA27344.

  16. Modeling surface imperfections in thin films and nanostructured surfaces

    DEFF Research Database (Denmark)

    Hansen, Poul-Erik; Madsen, J. S.; Jensen, S. A.

    2017-01-01

    Accurate scatterometry and ellipsometry characterization of non-perfect thin films and nanostructured surfaces are challenging. Imperfections like surface roughness make the associated modelling and inverse problem solution difficult due to the lack of knowledge about the imperfection on the surf......Accurate scatterometry and ellipsometry characterization of non-perfect thin films and nanostructured surfaces are challenging. Imperfections like surface roughness make the associated modelling and inverse problem solution difficult due to the lack of knowledge about the imperfection...... classes of imperfections are examined. The imperfections are introduced as periodic structures with a super cell periods ten times larger than the simple grating period. Two classes of imperfections concern the grating and one class concern the substrate. It is shown that imperfections of a few nanometers...

  17. Modelling driver behaviour in the case of failures in a steer by wire system

    NARCIS (Netherlands)

    Hogema, J.H.; Wewerinke, P.H.

    2012-01-01

    In the design and development of advanced vehicle control systems such as X-by-Wire (XBW), system safety is a crucial aspect. Failures in XBW can easily result in accidents. Therefore, methods and tools are needed to ensure fault-tolerant systems. Quantifying the consequence of an error is far from

  18. An integrated 3D sound intensity sensor using four-wire particle velocity sensors: II. Modelling

    NARCIS (Netherlands)

    Honschoten, van J.W.; Yntema, D.R.; Wiegerink, R.J.

    2010-01-01

    The sensitivity of a micromachined acoustic sensor consisting of four hot-wire particle velocity sensors is analysed theoretically and experimentally. The device and its fabrication have been presented in part 1 of this paper (Yntema et al 2010 J. Micromech. Microeng. 20 015042). A relatively straig

  19. Black Hole Entropy Calculation in a Modified Thin Film Model

    Indian Academy of Sciences (India)

    Jingyi Zhang

    2011-03-01

    The thin film model is modified to calculate the black hole entropy. The difference from the original method is that the Parikh–Wilczek tunnelling framework is introduced and the self-gravitation of the emission particles is taken into account. In terms of our improvement, if the entropy is still proportional to the area, then the emission energy of the particles will satisfy = /360.

  20. Cavitation during wire brushing

    Science.gov (United States)

    Li, Bo; Zou, Jun; Ji, Chen

    2016-11-01

    In our daily life, brush is often used to scrub the surface of objects, for example, teeth, pots, shoes, pool, etc. And cleaning rust and stripping paint are accomplished using wire brush. Wire brushes also can be used to clean the teeth for large animals, such as horses, crocodiles. By observing brushing process in water, we capture the cavitation phenomenon on the track of moving brush wire. It shows that the cavitation also can affect the surface. In order to take clear and entire pictures of cavity, a simplified model of one stainless steel wire brushing a boss is adopted in our experiment. A transparent organic tank filled with deionized water is used as a view box. And a high speed video camera is used to record the sequences. In experiment, ambient pressure is atmospheric pressure and deionized water temperature is kept at home temperature. An obvious beautiful flabellate cavity zone appears behind the moving steel wire. The fluctuation of pressure near cavity is recorded by a hydrophone. More movies and pictures are used to show the behaviors of cavitation bubble following a restoring wire. Beautiful tracking cavitation bubble cluster is captured and recorded to show.

  1. 超细金属丝中电子的关联函数和关联能%The Correlation Function and Correlation Energies of the Electron Gas in Ultra-thin Metal Wires

    Institute of Scientific and Technical Information of China (English)

    詹康生; 邵金山

    2000-01-01

    For the ultra- thin metal wires systems with coulomb interaction, a new quasi one - dimensionmodel is presented in thispaper. The form of effective coulomb potential for the ultra - thin metal wire systems is derived. Based on the correlated wave function theory, the Jastrow- Feenbery -stater many- body variation wave function is obtained on the basis of the collective oscillation behavior of the electron. gas. We have solved correlation function equation of real space and variation calculation to the system energies. 牋牋牋The pair correlation wave function and correlation energies and many- body wave function of ultrathin K wires are obtained. The pair correlation function obtained in this paper is positive definite and can satisfy the normalization condition.%对于具有库仑相互作用的超细金属丝,该文提出了一种新的准一维模型,从而得到了准一维超细金属丝体系的电子有效库仑势形式.并在相关基函数理论框架下,利用准一维电子体系的集体振荡行为,确定了具有库仑相互作用的二体关联的Jastrow-Feenberg-Slater多体变分波函数,通过对实空间关联函数的方程的自洽迭代求解以及体系能量的变分计算,得到了金属钾r5=4.967细丝的关联函数、关联能.该文得到的关联函数是恒正的,并且满足归一化条件.

  2. Study of pre-processing model of coal-mine hoist wire-rope fatigue damage signal

    Institute of Scientific and Technical Information of China (English)

    Tian Jie; Wang Hongyao⇑; Zhou Junying; Meng Guoying

    2015-01-01

    In this paper, we propose a pre-processing method for the detection of wire-rope signals. This is neces-sary because of the lack of processing methods that are currently employed. First, we investigated the one-dimensional discrete morphological and wavelet transform. Then, we developed a pre-processing model that is based on the morphological wavelet-filtering algorithm. We then proposed a modified morphology filtering algorithm. We also designed an experiment platform for wire-rope detection. Eight levels of localized flaws (LFs) and damage were formed in the wire-rope specimen. We performed a series of experimental studies, and the results show that the proposed method can effectively filter the drift signal. The signal-to-noise ratio of the new filtering algorithm was over 26 dB. The signal-to-noise ratio of the existing method is less than 15 dB, and the noise-signal ratio of the new filtering algorithm has improved by 73%. Based on our results, the filtering effect of the proposed method is better than that of the present method. This study has great significance and practical value in engineering applications.

  3. Dieless wire drawing with lasers

    Science.gov (United States)

    Liedl, G.; Schuöcker, D.

    2007-06-01

    Thin wires are produced by drawing through nozzle-like tools, so called dies, that suffer from strong wear due to friction. In order to avoid the latter disadvantage the dies can be replaced by a laser beam heating the wire to such extend that the yield strength becomes smaller than the tensile strength and thus the wire is elongated and consequently constricted. To avoid rupture, the wire is cooled down again after the desired reduction of the diameter is reached. A further important advantage of this new process is that only one drawing step with a laser can substitute a large number of mechanical drawing actions, thus making the process much more efficient. Theoretical considerations and experimental investigations prove the feasibility of the latter new laser process and are subject to a description in the actual paper.

  4. Low Temperature Silicon Nitride by Hot Wire Chemical Vapour Deposition for the Use in Impermeable Thin Film Encapsulation on Flexible Substrates

    NARCIS (Netherlands)

    Spee, D.A.; van der Werf, C.H.M.; Rath, J.K.; Schropp, R.E.I.

    2011-01-01

    High quality non porous silicon nitride layers were deposited by hot wire chemical vapour deposition at substrate temperatures lower than 110 C. The layer properties were investigated using FTIR, reflection/transmission measurements and 1:6 buffered HF etching rate. A Si–H peak position of 2180 cm−1

  5. Kirschner Wires : insertion techniques and bone related consequences

    NARCIS (Netherlands)

    Franssen, B.B.G.M.

    2010-01-01

    The Kirschner (K-) wire was first introduced in 1909 by Martin Kirschner. This is a thin unthreaded wire of surgical steel with a diameter of up to three millimeters and a selection of different tips. The use of K-wires is often promoted as a simple technique because of its easy placement, cost-effe

  6. COST-EFFECTIVE WIRE-HARNESS MODEL BY USING POLYMER OPTICAL FIBER

    OpenAIRE

    Mohammad Syuhaimi Ab-Rahman; Farshad Nasimi Khameneh

    2013-01-01

    In the past decade automotive industries faced the exponential increase of in-vehicle electronic devices. The hydraulic systems are replacing with sophisticate electronic systems. Market demands for exploiting new in-vehicle technologies such as multimedia systems, internet access, GPS, Mobile communication, internal private network; engine, body and power train intelligent control and monitoring systems are increasing daily. These new needs make the wire-harness as physical pathway for power...

  7. A new modeling of the initial buildup evolution on a wire in an axial HGMF filter

    Science.gov (United States)

    Badescu, V.; Murariu, V.; Rotariu, O.; Rezlescu, N.

    1996-10-01

    The buildup differential equations are solved for a single wire in the axial HGMF configuration. A new equation for the deposit contour surface at different moments for the initial buildup process is obtained. In addition, a limitation is obtained for the deposit surface, considering the balance between the magnetic force and the hydrodynamic erosion force. From this, the saturation accumulation radius is obtained in terms of the Reynolds' number for a particle and the {v m}/{v 0} ratio.

  8. A multiscale model for thin film AMR sensors

    Energy Technology Data Exchange (ETDEWEB)

    Bartok, Andras [Laboratoire de Genie Electrique de Paris, CNRS (UMR 8507)/SUPELEC/UPMC/Univ Paris-Sud, 11 rue Joliot Curie, 91192 Gif sur Yvette (France); Daniel, Laurent, E-mail: laurent.daniel@lgep.supelec.fr [Laboratoire de Genie Electrique de Paris, CNRS (UMR 8507)/SUPELEC/UPMC/Univ Paris-Sud, 11 rue Joliot Curie, 91192 Gif sur Yvette (France); Materials Science Centre, University of Manchester, M1 7HS Manchester (United Kingdom); Razek, Adel [Laboratoire de Genie Electrique de Paris, CNRS (UMR 8507)/SUPELEC/UPMC/Univ Paris-Sud, 11 rue Joliot Curie, 91192 Gif sur Yvette (France)

    2013-01-15

    AMR sensors are among the most widely deployed magnetic field sensors. In contrast to other technologies it has a simple structure and a low production cost. In this paper a multiscale modeling strategy is proposed to describe the performance of these sensors taking their specific features into account. The prediction of the behavior of a typical AMR thin film sensor has been studied and the results are compared to experimental measurements from the literature. The proposed micro-macro model offers an opportunity to investigate optimal material composition, crystallographic texture, film thickness or bias field level for specific applications. - Highlights: Black-Right-Pointing-Pointer A multiscale strategy for the modeling of thin film AMR sensors is proposed. Black-Right-Pointing-Pointer The approach is based on the changes under external loading of the free energy at the magnetic domains scale. Black-Right-Pointing-Pointer Small thickness and crystallographic texture effects are introduced in the modeling. Black-Right-Pointing-Pointer The behavior of commercial AMR sensors is satisfactorily modeled. Black-Right-Pointing-Pointer The role of the bias field and of the film thickness is discussed.

  9. Thin Filament Structure and the Steric Blocking Model.

    Science.gov (United States)

    Lehman, William

    2016-03-15

    By interacting with the troponin-tropomyosin complex on myofibrillar thin filaments, Ca2+ and myosin govern the regulatory switching processes influencing contractile activity of mammalian cardiac and skeletal muscles. A possible explanation of the roles played by Ca2+ and myosin emerged in the early 1970s when a compelling "steric model" began to gain traction as a likely mechanism accounting for muscle regulation. In its most simple form, the model holds that, under the control of Ca2+ binding to troponin and myosin binding to actin, tropomyosin strands running along thin filaments either block myosin-binding sites on actin when muscles are relaxed or move away from them when muscles are activated. Evidence for the steric model was initially based on interpretation of subtle changes observed in X-ray fiber diffraction patterns of intact skeletal muscle preparations. Over the past 25 years, electron microscopy coupled with three-dimensional reconstruction directly resolved thin filament organization under many experimental conditions and at increasingly higher resolution. At low-Ca2+, tropomyosin was shown to occupy a "blocked-state" position on the filament, and switched-on in a two-step process, involving first a movement of tropomyosin away from the majority of the myosin-binding site as Ca2+ binds to troponin and then a further movement to fully expose the site when small numbers of myosin heads bind to actin. In this contribution, basic information on Ca2+-regulation of muscle contraction is provided. A description is then given relating the voyage of discovery taken to arrive at the present understanding of the steric regulatory model.

  10. Beam Interaction with Thin Materials: Heat Deposition, Cooling Phenomena and Damage Limits

    CERN Document Server

    Sapinski, M

    2012-01-01

    Thin targets, inserted into particle beams can serve various purposes, starting from beam emittance measurements like in wire scanner or scintillating screens up to beam content modifications like in case of stripper foils. The mechanisms of energy deposition in a thin target for various beam types are discussed, together with properties of particles produced in this kind of interaction. The cooldown processes, from heat transfer up to cooling by sublimation, and their efficiencies are presented. Finally, damage conditions are discussed and conclusions about typical damage limits are drawn. The experiments performed with the wire scanners at CERN accelerators and a mathematical model of heating and cooling of a wire are presented.

  11. Time and frequency response of a resistance-wire aircraft atmospheric temperature sensor

    Science.gov (United States)

    Payne, G. A.; Friehe, C. A.; Edwards, D. K.

    1994-04-01

    The heat transfer characteristics of an aircraft-mounted resistance-wire atmospheric temperature sensor are modeled to determine the time and frequency responses. The sensor element (Rosemount 102E4AL) consists of a 25-micron-diameter platinum wire wound around a cruciform mica support with approximately 143 diameters of wire between contacts with the mica. A longitudinally distributed, radially lumped capacitance model provided for the convective heat transfer to the wire and the transient heat conduction along it. Similarly, the temperature gradient across the thin dimension of the mica support was neglected, and a radially distributed model provided for the convective heat transfer to the mica and the transient conduction within it. The two solutions are coupled by the boundary conditions at the wire-mica contact. The equations were solved to produce the temperature distribution along the wire and in the mica support as a function of the frequency of a free-stream sinusoidal temperature fluctuation. The frequency response transfer function was determined and fit to a two-time-constant transfer function by regression analysis. The two-time-constant model fits the general solution very well. The small (fast response) time constant is essentially determined by the wire itself. The larger (slow response) time constant is due to conduction into and out of the mica supports. The model predicts that the effects of the mica supports are important for frequencies greater than about 0.1 Hz. The responses to five different temperature waveform inputs (sinusoid, step, pulse, ramp, and ramp level) are derived using the two-time-constant model with Laplace transform techniques for both infinite-length wire (no mica support effects) and the finite-length wire of the 102 probe. The actual temperature signals are distorted by the larger time constant of the mica supports, especially for the pulse and ramp inputs that are typical of aircraft measurements of thermals and

  12. Thin layer modelling of Gelidium sesquipedale solar drying process

    Energy Technology Data Exchange (ETDEWEB)

    Ait Mohamed, L. [Laboratoire d' Energie Solaire et des Plantes Aromatiques et Medicinales, Ecole Normale Superieure, BP 2400, Marrakech (Morocco); Faculte des Sciences Semlalia, BP 2390, Marrakech (Morocco); Ethmane Kane, C.S. [Faculte des Sciences de Tetouan, BP 2121, Tetouan (Morocco); Kouhila, M.; Jamali, A. [Laboratoire d' Energie Solaire et des Plantes Aromatiques et Medicinales, Ecole Normale Superieure, BP 2400, Marrakech (Morocco); Mahrouz, M. [Faculte des Sciences Semlalia, BP 2390, Marrakech (Morocco); Kechaou, N. [Ecole Nationale d' Ingenieurs de Sfax, BPW 3038 (Tunisia)

    2008-05-15

    The effect of air temperature and air flow rate on the drying kinetics of Gelidium sesquipedale was investigated in convective solar drying. Drying was conducted at 40, 50 and 60 C. The relative humidity was varied from 50% to 57%, and the drying air flow rate was varied from 0.0277 to 0.0833 m{sup 3}/s. The expression for the drying rate equation is determined empirically from the characteristic drying curve. Thirteen mathematical models of thin layer drying are selected in order to estimate the suitable model for describing the drying curves. The two term model gives the best prediction of the drying curves and satisfactorily describes the drying characteristics of G. sesquipedale with a correlation coefficient R of 0.9999 and chi-square ({chi}{sup 2}) of 3.381 x 10{sup -6}. (author)

  13. Wire Chamber

    CERN Multimedia

    1986-01-01

    Two wire chambers made originally for the R807 Experiment at CERN's Intersecting Storage Rings. In 1986 they were used for the PS 201 experiment (Obelix Experiment) at LEAR, the Low Energy Antiproton Ring. The group of researchers from Turin, using the chambers at that time, changed the acquisition system using for the first time 8 bit (10 bit non linear) analog to digital conversion for incoming signals from the chambers. The acquisition system was controlled by 54 CPU and 80 digital signal processors. The power required for all the electronics was 40 kW. For the period, this system was one of the most powerful on-line apparatus in the world. The Obelix Experiment was closed in 1996. To find more about how a wire chamber works, see the description for object CERN-OBJ-DE-038.

  14. One-wire thermocouple

    Science.gov (United States)

    Goodrich, W. D.; Staimach, C. J.

    1977-01-01

    Nickel alloy/constantan device accurately measures surface temperature at precise locations. Device is moderate in cost and simplifies fabrication of highly-instrumented seamless-surface heat-transfer models. Device also applies to metal surfaces if constantan wire has insulative coat.

  15. Modeling and optimization of process variables of wire-cut electric discharge machining of super alloy Udimet-L605

    Directory of Open Access Journals (Sweden)

    Somvir Singh Nain

    2017-02-01

    Full Text Available This paper presents the behavior of Udimet-L605 after wire electric discharge machining and evaluating the WEDM process using sophisticated machine learning approaches. The experimental work is depicted on the basis of Taguchi orthogonal L27 array, considering six input variables and three interactions. Three models such as support vector machine algorithms based on PUK kernel, non-linear regression and multi-linear regression have been proposed to examine the variance between experimental and predicted outcome and preferred the preeminent model based on its evaluation parameters performance and graph analysis. The grey relational analysis is the relevant approach to obtain the best grouping of input variables for maximum material removal rate and minimum surface roughness. Based on statistical analysis, it has been concluded that pulse-on time, interaction between pulse-on time x pulse-off time, spark-gap voltage and wire tension are the momentous variable for surface roughness while the pulse-on time, spark-gap voltage and pulse-off time are the momentous variables for material removal rate. The micro structural and compositional changes on the surface of work material were examined by means of SEM and EDX analysis. The thickness of the white layer and the recast layer formation increases with increases in the pulse-on time duration.

  16. Modelling and analysis of material removal rate and surface roughness in wire-cut EDM of armour materials

    Directory of Open Access Journals (Sweden)

    Ravindranadh Bobbili

    2015-12-01

    Full Text Available The current work presents a comparative study of wire electrical discharge machining (WEDM of armour materials such as aluminium alloy 7017 and rolled homogeneous armour (RHA steel using buckingham pi theorem to model the input variables and thermo-physical characteristics of WEDM on material removal rate (MRR and surface roughness (Ra of Al 7017 and RHA steel. The parameters of the model such as pulse-on time, flushing pressure, input power, thermal diffusivity and latent heat of vaporization have been determined through design of experiment methodology. Wear rate of brass wire increases with rise in input energy in machining Al 7017. The dependence of thermo-physical properties and machining variables on mechanism of MRR and Ra has been described by performing scanning electron microscope (SEM study. The rise in pulse-on time from 0.85μs to 1.25μs causes improvement in MRR and deterioration of surface finish. The machined surface has revealed that craters are found on the machined surface. The propensity of formation of craters increases during WEDM with a higher current and larger pulse-on time.

  17. Random field distributed Heisenberg model on a thin film geometry

    Energy Technology Data Exchange (ETDEWEB)

    Akıncı, Ümit, E-mail: umit.akinci@deu.edu.tr

    2014-11-15

    The effects of the bimodal random field distribution on the thermal and magnetic properties of the Heisenberg thin film have been investigated by making use of a two spin cluster with the decoupling approximation. Particular attention has been devoted to the obtaining of phase diagrams and magnetization behaviors. The physical behaviors of special as well as tricritical points are discussed for a wide range of selected Hamiltonian parameters. For example, it is found that when the strength of a magnetic field increases, the locations of the special point (which is the ratio of the surface exchange interaction and the exchange interaction of the inner layers that makes the critical temperature of the film independent of the thickness) in the related plane decrease. Moreover, tricritical behavior has been obtained for higher values of the magnetic field, and influences of the varying Hamiltonian parameters on its behavior have been elucidated in detail in order to have a better understanding of the mechanism underlying the considered system. - Highlights: • Effect of bimodal random field distribution within the Heisenberg model is investigated. • Phase diagrams of the random field Heisenberg model in a thin film geometry are obtained. • Effect of the random field on the magnetic properties is obtained. • Variation of the special point with random field is determined. • Variation of the tricritical point with random field is determined.

  18. Modeling the buckling and delamination of thin films

    Science.gov (United States)

    Jagla, E. A.

    2007-02-01

    I study numerically the problem of delamination of a thin film elastically attached to a rigid substrate. A nominally flat elastic thin film is modeled using a two-dimensional triangular mesh. Both compression and bending rigidities are included to simulate compression and bending of the film. The film can buckle (i.e., abandon its flat configuration) when enough compressive strain is applied. The buckled configurations of a piece of film with stripe geometry are investigated as a function of the compressive strain. It is found that the stable configuration depends strongly on the applied strain and the Poisson ratio of the film. Next, the film is considered to be attached to a rigid substrate by springs that can break when the detaching force exceeds a threshold value, producing partial delamination of the film. Delamination is induced by a mismatch of the relaxed configurations of film and substrate. The morphology of the delaminated film can be followed and compared with available experimental results as a function of model parameters. “Telephone-cord,” polygonal, and “brainlike” patterns qualitatively similar to experimentally observed configurations are obtained in different parameter regions. The main control parameters that select the different patterns are the strain mismatch between film and substrate and the degree of in-plane relaxation within the unbuckled regions.

  19. 3D full circumference modelling of wire array Z-pinches

    Science.gov (United States)

    Chittenden, J. P.; Lebedev, S. V.; Bland, S. N.; Jennings, C. A.; Ciardi, A.

    2003-10-01

    Resistive magneto-hydrodynamic simulations are used to evaluate the influence of 3D inhomogeneities on X-ray power production in wire array Z-pinches. An initial temperature perturbation is used to stimulate variations in core ablation rates which result in a highly non-uniform final implosion. Results indicate that X-ray power production is governed by the rate at which current can transfer to the axis through a 3D debris field which trails behind the main implosion. Three dominant sources of power input to the pinch, and hence X-ray production, are identified. The first is the implosion of a large fraction of the array mass at moderate velocity. The second is the later implosion of a smaller mass fraction at higher velocity which carries the majority of current. Finally the contribution of Ohmic heating to the power input becomes significant. The peak power is ultimately limited by the onset of MHD instabilities in the stagnated pinch. Mechanisms for the influence of wire number, material and nesting on X-ray power production are presented. This research was sponsored by the NNSA under DOE Cooperative Agreement DE-F03-02NA00057.

  20. Basic study on hot-wire flow meter in forced flow of liquid hydrogen

    Science.gov (United States)

    Oura, Y.; Shirai, Y.; Shiotsu, M.; Murakami, K.; Tatsumoto, H.; Naruo, Y.; Nonaka, S.; Kobayashi, H.; Inatani, Y.; Narita, N.

    2014-01-01

    Liquid hydrogen (LH2) is a key issue in a carbon-free energy infrastructure at the energy storage and transportation stage. The typical features of LH2 are low viscosity, large latent heat and small density, compared with other general liquids. It is necessary to measure a mass flow of liquid hydrogen with a simple and compact method, especially in a two phase separate flow condition. We have proposed applying a hot-wire type flow meter, which is usually used a for gas flow meter, to LH2 flow due to the quite low viscosity and density. A test model of a compact LH2 hot-wire flow meter to measure local flow velocities near and around an inside perimeter of a horizontal tube by resistance thermometry was designed and made. The model flow meter consists of two thin heater wires made of manganin fixed in a 10 mm-diameter and 40 mm-length tube flow path made of GFRP. Each rigid heater wire was set twisted by 90 degrees from the inlet to the outlet along the inner wall. In other words, the wires were aslant with regard to the LH2 stream line. The heated wire was cooled by flowing LH2, and the flow velocity was obtained by means of the difference of the cooling characteristic in response to the flow velocity. In this report, we show results on the basic experiments with the model LH2 hot-wire flow meter. First, the heat transfer characteristics of the two heater wires for several LH2 flow velocities were measured. Second, the heating current was controlled to keep the wire temperature constant for various flow velocities. The relations between the flow velocity and the heating current were measured. The feasibility of the proposed model was confirmed.

  1. Modeling and Simulation of SMA Wire Actuator%SMA驱动丝的建模与仿真

    Institute of Scientific and Technical Information of China (English)

    杨士斌; 徐敏

    2012-01-01

    研究SMA动力学优化模型,针对形状记忆合金(SMA)驱动丝具有强非线性、迟滞效应等特性,为设计SMA驱动丝的自适应结构,提出建立SMA驱动丝模型并提供高效的仿真方法.采用有限元软件实现了受轴向载荷的SMA驱动丝的仿真建模.对本构模型是根据自由能的一维热-力学耦合模型,可以同时复现形状记忆效应和超弹性.数值仿真能够引起材料相变的非均匀温度和应变分布.仿真结果表明,建立热-力学耦合模型,可为设计SMA驱动丝的自适应结构计算提供可靠依据.%Shape memory alloy (SMA) shows high nonlinear and hysteretic phenomenon. In order to design SMA based adaptive structure, it is necessary to model and simulate the wire actuator in an efficient way. A thermo - mechanical model of SMA wire under uniaxial loading was implemented in finite element codes. The constitutive model is a one dimensional model which based on free energy and motivated by statistical thermodynamics. The model has the ability to represent both shape memory effect and pseudoelasticity. The numerical simulations can capture the inhomogeneous thermal and strain distribution which triggers the phase transformation locally. After investigation under different convective boundary conditions, the result shows that an obvious stroke lost happened in fixed temperature case comparing with adiabatic thermal boundary conditions which come from the thermo-mechanical coupling effect.

  2. Modeling the Radar Signature of Thin Metallic Objects with the AFDTD Software

    Science.gov (United States)

    2014-09-01

    Modeling the Radar Signature of Thin Metallic Objects with the AFDTD Software by Jason Cornelius and Traian Dogaru ARL-TR-7063...7063 September 2014 Modeling the Radar Signature of Thin Metallic Objects with the AFDTD Software Jason Cornelius and Traian Dogaru...Final 3. DATES COVERED (From - To) June–August 2014 4. TITLE AND SUBTITLE Modeling the Radar Signature of Thin Metallic Objects with the AFDTD

  3. Prototypical model for tensional wrinkling in thin sheets

    KAUST Repository

    Davidovitch, B.

    2011-10-31

    The buckling and wrinkling of thin films has recently seen a surge of interest among physicists, biologists, mathematicians, and engineers. This activity has been triggered by the growing interest in developing technologies at ever-decreasing scales and the resulting necessity to control the mechanics of tiny structures, as well as by the realization that morphogenetic processes, such as the tissue-shaping instabilities occurring in animal epithelia or plant leaves, often emerge from mechanical instabilities of cell sheets. Although the most basic buckling instability of uniaxially compressed plates was understood by Euler more than two centuries ago, recent experiments on nanometrically thin (ultrathin) films have shown significant deviations from predictions of standard buckling theory. Motivated by this puzzle, we introduce here a theoretical model that allows for a systematic analysis of wrinkling in sheets far from their instability threshold. We focus on the simplest extension of Euler buckling that exhibits wrinkles of finite length--a sheet under axisymmetric tensile loads. The first study of this geometry, which is attributed to Lamé, allows us to construct a phase diagram that demonstrates the dramatic variation of wrinkling patterns from near-threshold to far-from-threshold conditions. Theoretical arguments and comparison to experiments show that the thinner the sheet is, the smaller is the compressive load above which the far-from-threshold regime emerges. This observation emphasizes the relevance of our analysis for nanomechanics applications.

  4. A model for pressurized hydrogen induced thin film blisters

    Science.gov (United States)

    van den Bos, R. A. J. M.; Reshetniak, V.; Lee, C. J.; Benschop, J.; Bijkerk, F.

    2016-12-01

    We introduce a model for hydrogen induced blister formation in nanometer thick thin films. The model assumes that molecular hydrogen gets trapped under a circular blister cap causing it to deflect elastically outward until a stable blister is formed. In the first part, the energy balance required for a stable blister is calculated. From this model, the adhesion energy of the blister cap, the internal pressure, and the critical H-dose for blister formation can be calculated. In the second part, the flux balance required for a blister to grow to a stable size is calculated. The model is applied to blisters formed in a Mo/Si multilayer after being exposed to hydrogen ions. From the model, the adhesion energy of the Mo/Si blister cap was calculated to be around 1.05 J/m2 with internal pressures in the range of 175-280 MPa. Based on the model, a minimum ion dose for the onset of blister formation was calculated to be d = 4.2 × 1018 ions/cm2. From the flux balance equations, the diffusion constant for the Mo/Si blister cap was estimated to be DH2=(10 ±1 )×10-18 cm2/s .

  5. Thin plate neotectonic models of the Australian plate

    Science.gov (United States)

    Burbidge, D. R.

    2004-10-01

    Thin plate finite element models of the neotectonic deformation of the Australian plate have been calculated in order to estimate the stress and strain rate within the plate, specifically concentrating on the Australian continent. The model includes plate-bounding faults, an anelastic brittle-ductile layered rheology and the option of laterally varying elevation and heat flow. The results of the models are compared to (1) the velocity of geodetic benchmarks on the Australian plate, (2) the spreading rate of the mid-oceanic ridges along the Australian plate's margins, (3) the direction of the maximum horizontal principal stress, (4) the stress regime within the plate, and (5) the crustal thickness estimated from the depth to the base of Mohorovicic discontinuity's transition zone. A variety of models are tested with a wide range of input parameters. The model with the smallest misfit with observations predicts that the strain rate for most of the Australian continent is approximately 10-17 s-1. This model has a slightly lower strain rate in the central Australia and is higher off the northern coast of Australia than for the rest of the continent. Strain rates of this magnitude would be difficult to observe from geodetic or geologic data for most parts of Australia but would be enough to generate much of the seismicity that has been observed over the last century.

  6. Research on the Wire Network Signal Prediction Based on the Improved NNARX Model

    Science.gov (United States)

    Zhang, Zipeng; Fan, Tao; Wang, Shuqing

    It is difficult to obtain accurately the wire net signal of power system's high voltage power transmission lines in the process of monitoring and repairing. In order to solve this problem, the signal measured in remote substation or laboratory is employed to make multipoint prediction to gain the needed data. But, the obtained power grid frequency signal is delay. In order to solve the problem, an improved NNARX network which can predict frequency signal based on multi-point data collected by remote substation PMU is describes in this paper. As the error curved surface of the NNARX network is more complicated, this paper uses L-M algorithm to train the network. The result of the simulation shows that the NNARX network has preferable predication performance which provides accurate real time data for field testing and maintenance.

  7. Study of porogen removal by atomic hydrogen generated by hot wire chemical vapor deposition for the fabrication of advanced low-k thin films

    Energy Technology Data Exchange (ETDEWEB)

    Godavarthi, S., E-mail: srinivas@cinvestav.mx [Program of Nanoscience and Nanotechnology, Cinvestav-IPN (Mexico); Universidad Nacional Autonoma de Mexico, Instituto de Ciencias Fisicas, Av. Universidad, Cuernavaca, Morelos (Mexico); Wang, C.; Verdonck, P. [imec, Kapeldreef 75, 3001 Leuven (Belgium); Matsumoto, Y.; Koudriavtsev, I. [Program of Nanoscience and Nanotechnology, Cinvestav-IPN (Mexico); SEES, Electrical Engineering Department, Cinvestav-IPN (Mexico); Dutt, A. [SEES, Electrical Engineering Department, Cinvestav-IPN (Mexico); Tielens, H.; Baklanov, M.R. [imec, Kapeldreef 75, 3001 Leuven (Belgium)

    2015-01-30

    In order to obtain low-k dielectric films, a subtractive technique, which removes sacrificial porogens from a hydrogenated silicon oxycarbide (SiOC:H) film, has been used successfully by different groups in the past. In this paper, we report on the porogen removal from porogenated SiOC:H films, using a hot wire chemical vapor deposition (HWCVD) equipment. Molecular hydrogen is dissociated into atomic hydrogen by the hot wires and these atoms may successfully remove the hydrocarbon groups from the porogenated SiOC:H films. The temperature of the HWCVD filaments proved to be a determining factor. By Fourier transform infrared spectroscopy, X-ray reflectivity (XRR), secondary ion mass spectrometry (SIMS), ellipsometric porosimetry and capacitance-voltage analyses, it was possible to determine that for temperatures higher than 1700 °C, efficient porogen removal occurred. For temperatures higher than 1800 °C, the presence of OH groups was detected. The dielectric constant was the lowest, 2.28, for the samples processed at a filament temperature of 1800 °C, although porosity measurements showed higher porosity for the films deposited at the higher temperatures. XRR and SIMS analyses indicated densification and Tungsten (W) incorporation at the top few nanometers of the films.

  8. FDTD subcell graphene model beyond the thin-film approximation

    CERN Document Server

    Valuev, Ilya; Bogdanova, Maria; Kotov, Oleg; Lozovik, Yurii

    2016-01-01

    A subcell technique for calculation of optical properties of graphene with the finite-difference time-domain (FDTD) method is presented. The technique takes into account the surface conductivity of graphene which allows the correct calculation of its dispersive response for arbitrarily polarized incident waves interacting with the graphene.The developed technique is verified for a planar graphene sheet configuration against the exact analytical solution. Based on the same test case scenario, we also show that the subcell technique demonstrates a superior accuracy and numerical efficiency with respect to the widely used thin-film FDTD approach for modeling graphene. We further apply our technique to the simulations of a graphene metamaterial containing periodically spaced graphene strips (graphene strip-grating) and demonstrate good agreement with the available theoretical results.

  9. Model of a thin film optical fiber fluorosensor

    Science.gov (United States)

    Egalon, Claudio O.; Rogowski, Robert S.

    1991-03-01

    The efficiency of core-light injection from sources in the cladding of an optical fiber is modeled analytically by means of the exact field solution of a step-profile fiber. The analysis is based on the techniques by Marcuse (1988) in which the sources are treated as infinitesimal electric currents with random phase and orientation that excite radiation fields and bound modes. Expressions are developed based on an infinite cladding approximation which yield the power efficiency for a fiber coated with fluorescent sources in the core/cladding interface. Marcuse's results are confirmed for the case of a weakly guiding cylindrical fiber with fluorescent sources uniformly distributed in the cladding, and the power efficiency is shown to be practically constant for variable wavelengths and core radii. The most efficient fibers have the thin film located at the core/cladding boundary, and fibers with larger differences in the indices of refraction are shown to be the most efficient.

  10. Light self-focusing in the atmosphere: thin window model

    Science.gov (United States)

    Vaseva, Irina A.; Fedoruk, Mikhail P.; Rubenchik, Alexander M.; Turitsyn, Sergei K.

    2016-08-01

    Ultra-high power (exceeding the self-focusing threshold by more than three orders of magnitude) light beams from ground-based laser systems may find applications in space-debris cleaning. The propagation of such powerful laser beams through the atmosphere reveals many novel interesting features compared to traditional light self-focusing. It is demonstrated here that for the relevant laser parameters, when the thickness of the atmosphere is much shorter than the focusing length (that is, of the orbit scale), the beam transit through the atmosphere in lowest order produces phase distortion only. This means that by using adaptive optics it may be possible to eliminate the impact of self-focusing in the atmosphere on the laser beam. The area of applicability of the proposed “thin window” model is broader than the specific physical problem considered here. For instance, it might find applications in femtosecond laser material processing.

  11. Ionization Modeling Astrophysical Gaseous Structures. I. The Optically Thin Regime

    CERN Document Server

    Churchill, Christopher W; Medina, Amber; Vliet, Jacob R Vander

    2014-01-01

    We present a code for modelling the ionization conditions of optically thin astrophysical gas structures. Given the gas hydrogen density, equilibrium temperature, elemental abundances, and the ionizing spectrum, the code solves the equilibrium ionization fractions and number densities for all ions from hydrogen to zinc. The included processes are photoionization, Auger ionization, direct collisional ionization, excitation auto-ionization, charge exchange ionization, two-body radiative recombination, dielectronic recombination, and charge exchange recombination. The ionizing spectrum can be generalized to include the ultraviolet background (UVB) and/or Starburst99 stellar populations of various masses, ages, metallicities, and distances. The ultimate goal with the code is to provide fast computation of the ionization conditions of gas in N-body + hydrodynamics cosmological simulations, in particular adaptive mesh refinement codes, in order to facilitate absorption line analysis of the simulated gas for compari...

  12. Metallic Tungsten Nanostructures and Highly Nanostructured Thin Films by Deposition of Tungsten Oxide and Subsequent Reduction in a Single Hot-Wire CVD Process

    NARCIS (Netherlands)

    Harks, P.P.R.M.L.; Houweling, Z.S.; de Jong, M.M.; Kuang, Y; Geus, J.W.; Schropp, R.E.I.

    2012-01-01

    The synthesis of metallic tungsten nanostructures and highly nanostructured thin films is presented. Crystalline tungsten oxide nanostructures are deposited on glassy carbon substrates kept at 700 100 8C by oxidizing resistively heated tungsten filaments in an air flow under subatmospheric pressures

  13. Modeling thin-film piezoelectric polymer ultrasonic sensors

    Science.gov (United States)

    González, M. G.; Sorichetti, P. A.; Santiago, G. D.

    2014-11-01

    This paper presents a model suitable to design and characterize broadband thin film sensors based on piezoelectric polymers. The aim is to describe adequately the sensor behavior, with a reasonable number of parameters and based on well-known physical equations. The mechanical variables are described by an acoustic transmission line. The electrical behavior is described by the quasi-static approximation, given the large difference between the velocities of propagation of the electrical and mechanical disturbances. The line parameters include the effects of the elastic and electrical properties of the material. The model was validated with measurements of a poly(vinylidene flouride) sensor designed for short-pulse detection. The model variables were calculated from the properties of the polymer at frequencies between 100 Hz and 30 MHz and at temperatures between 283 K and 313 K, a relevant range for applications in biology and medicine. The simulations agree very well with the experimental data, predicting satisfactorily the influence of temperature and the dielectric properties of the polymer on the behavior of the sensor. Conversely, the model allowed the calculation of the material dielectric properties from the measured response of the sensor, with good agreement with the published values.

  14. TEMPERATURE-DEFORMATION CRITERION OF OPTIMIZATION OF FINE DRAWING HIGH CARBON WIRE ROUTE

    Directory of Open Access Journals (Sweden)

    Y. L. Bobarikin

    2012-01-01

    Full Text Available The temperature-deformation criterion of assessment and optimization of routes of the thin high-carbon wire drawing enabling to increase plastic properties of wire at retaining of its durability is offered.

  15. Microstructure changes during non-conventional heat treatment of thin Ni-Ti wires by pulsed electric current studied by transmission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Delville, R., E-mail: remi.delville@ua.ac.be [EMAT, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Malard, B.; Pilch, J.; Sittner, P. [Institute of Physics, Na Slovance 2, 182 21 Praha (Czech Republic); Schryvers, D. [EMAT, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium)

    2010-08-15

    Transmission electron microscopy, electrical resistivity measurements and mechanical testing were employed to investigate the evolution of microstructure and functional superelastic properties of 0.1 mm diameter as-drawn Ni-Ti wires subjected to a non-conventional heat treatment by controlled electric pulse currents. This method enables a better control of the recovery and recrystallization processes taking place during the heat treatment and accordingly a better control on the final microstructure. Using a stepwise approach of millisecond pulse annealing, it is shown how the microstructure evolves from a severely deformed state with no functional properties to an optimal nanograined microstructure (20-50 nm) that is partially recovered through polygonization and partially recrystallized and that has the best functional properties. Such a microstructure is highly resistant against dislocation slip upon cycling, while microstructures annealed for longer times and showing mostly recrystallized grains were prone to dislocation slip, particularly as the grain size exceeds 200 nm.

  16. Low temperature silicon nitride by hot wire chemical vapour deposition for the use in impermeable thin film encapsulation on flexible substrates.

    Science.gov (United States)

    Spee, D A; van der Werf, C H M; Rath, J K; Schropp, R E I

    2011-09-01

    High quality non porous silicon nitride layers were deposited by hot wire chemical vapour deposition at substrate temperatures lower than 110 degrees C. The layer properties were investigated using FTIR, reflection/transmission measurements and 1:6 buffered HF etching rate. A Si-H peak position of 2180 cm(-1) in the Fourier transform infrared absorption spectrum indicates a N/Si ratio around 1.2. Together with a refractive index of 1.97 at a wavelength of 632 nm and an extinction coefficient of 0.002 at 400 nm, this suggests that a transparent high density silicon nitride material has been made below 110 degrees C, which is compatible with polymer films and is expected to have a high impermeability. To confirm the compatibility with polymer films a silicon nitride layer was deposited on poly(glycidyl methacrylate) made by initiated chemical vapour deposition, resulting in a highly transparent double layer.

  17. A multiscale and multiphysics model of strain development in a 1.5 T MRI magnet designed with 36 filament composite MgB2 superconducting wire

    Science.gov (United States)

    Amin, Abdullah Al; Baig, Tanvir; Deissler, Robert J.; Yao, Zhen; Tomsic, Michael; Doll, David; Akkus, Ozan; Martens, Michael

    2016-05-01

    High temperature superconductors such as MgB2 focus on conduction cooling of electromagnets that eliminates the use of liquid helium. With the recent advances in the strain sustainability of MgB2, a full body 1.5 T conduction cooled magnetic resonance imaging (MRI) magnet shows promise. In this article, a 36 filament MgB2 superconducting wire is considered for a 1.5 T full-body MRI system and is analyzed in terms of strain development. In order to facilitate analysis, this composite wire is homogenized and the orthotropic wire material properties are employed to solve for strain development using a 2D-axisymmetric finite element analysis (FEA) model of the entire set of MRI magnet. The entire multiscale multiphysics analysis is considered from the wire to the magnet bundles addressing winding, cooling and electromagnetic excitation. The FEA solution is verified with proven analytical equations and acceptable agreement is reported. The results show a maximum mechanical strain development of 0.06% that is within the failure criteria of -0.6% to 0.4% (-0.3% to 0.2% for design) for the 36 filament MgB2 wire. Therefore, the study indicates the safe operation of the conduction cooled MgB2 based MRI magnet as far as strain development is concerned.

  18. Nonlinear absorption coefficient and optically detected electrophonon resonance in cylindrical GaAs/AlAs quantum wires with different confined phonon models

    Science.gov (United States)

    Khoa, Doan Quoc; Phuong, Le Thi Thu; Hoi, Bui Dinh

    2017-03-01

    A quantum kinetic equation for electrons interacting with confined phonons is used to investigate the nonlinear absorption of an intense electromagnetic wave by electrons in cylindrical GaAs/AlAs quantum wires. The analytic expression for absorption coefficient is calculated for three models of confined optical phonons: the dielectric continuum (DC), hydrodynamic continuum (HC), and Huang-Zhu (HZ) models. The absorption coefficient depends on the square of the electromagnetic wave amplitude. The electrophonon resonance and optically detected electrophonon resonance (ODEPR) are observed through the absorption spectrum. The full width at half maximum (the line-width) of the ODEPR peaks is obtained by a computational method. The line-width is found to increase with increasing temperature and decrease with increasing the quantum wire radius. In particular, numerical results show that the DC and HZ models lead to a similar behaviour of electron - confined phonon interaction whereas the HC model results in a quite different one, especially at small quantum wire radius. For large quantum wire radii, above mentioned phonon models have equivalent contributions to the ODEPR line-width.

  19. A modelling study of moisture redistribution by thin cirrus clouds

    Directory of Open Access Journals (Sweden)

    T. Dinh

    2014-05-01

    Full Text Available A high resolution 2-dimensional numerical model is used to study the moisture redistribution following homogeneous ice nucleation induced by Kelvin waves in the tropical tropopause layer (TTL. We compare results for dry/moist initial conditions, and three levels of complexity for the representation of cloud processes: full bin microphysics and radiative effects of the ice, ditto but without radiative effects, and instantaneous removal of moisture in excess of saturation upon nucleation. Cloud evolution and the profiles of moisture redistribution are found to be sensitive to initial conditions and cloud processes. Ice sedimentation leads to a downward flux of water. On the other hand, the cloud radiative heating induces upward advection of the cloudy air. This results in an upward flux of water vapour if the cloudy air is moister (or drier than the environment, which is typically when the environment is subsaturated (or supersaturated. The numerical results show that only a small fraction (less than 25% of the cloud experiences nucleation. Sedimentation and reevaporation are important, and hydrated layers in observation may be as good an indicator as dehydrated layers for the occurrence of thin cirrus clouds. The calculation with instantaneous removal of condensates misses the hydration by construction, but also underestimates dehydration due to lack of moisture removal from sedimenting particles below the nucleation level, and due to nucleation before reaching the minimum saturation mixing ratio. The sensitivity to initial conditions and cloud processes suggests that it is difficult to reach generic, quantitative conclusions regarding the role of thin cirrus clouds for the moisture distribution in the TTL and stratosphere.

  20. Spectroscopic properties of colloidal indium phosphide quantum wires

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Lin-Wang; Wang, Fudong; Yu, Heng; Li, Jingbo; Hang, Qingling; Zemlyanov, Dmitry; Gibbons, Patrick C.; Wang, Lin-Wang; Janes, David B.; Buhro, William E.

    2008-07-11

    Colloidal InP quantum wires are grown by the solution-liquid-solid (SLS) method, and passivated with the traditional quantum dots surfactants 1-hexadecylamine and tri-n-octylphosphine oxide. The size dependence of the band gaps in the wires are determined from the absorption spectra, and compared to other experimental results for InP quantum dots and wires, and to the predictions of theory. The photoluminescence behavior of the wires is also investigated. Efforts to enhance photoluminescence efficiencies through photochemical etching in the presence of HF result only in photochemical thinning or photo-oxidation, without a significant influence on quantum-wire photoluminescence. However, photo-oxidation produces residual dot and rod domains within the wires, which are luminescent. The results establish that the quantum-wire band gaps are weakly influenced by the nature of the surface passivation, and that colloidal quantum wires have intrinsically low photoluminescence efficiencies.

  1. Spectroscopic properties of colloidal indium phosphide quantum wires.

    Science.gov (United States)

    Wang, Fudong; Yu, Heng; Li, Jingbo; Hang, Qingling; Zemlyanov, Dmitry; Gibbons, Patrick C; Wang, Lin-Wang; Janes, David B; Buhro, William E

    2007-11-21

    Colloidal InP quantum wires are grown by the solution-liquid-solid (SLS) method, and passivated with the traditional quantum dots surfactants 1-hexadecylamine and tri-n-octylphosphine oxide. The size dependence of the band gaps in the wires are determined from the absorption spectra, and compared to other experimental results for InP quantum dots and wires, and to the predictions of theory. The photoluminescence behavior of the wires is also investigated. Efforts to enhance photoluminescence efficiencies through photochemical etching in the presence of HF result only in photochemical thinning or photooxidation, without a significant influence on quantum-wire photoluminescence. However, photooxidation produces residual dot and rod domains within the wires, which are luminescent. The results establish that the quantum-wire band gaps are weakly influenced by the nature of the surface passivation and that colloidal quantum wires have intrinsically low photoluminescence efficiencies.

  2. Presenting Thin Media Models Affects Women's Choice of Diet or Normal Snacks

    Science.gov (United States)

    Krahe, Barbara; Krause, Christina

    2010-01-01

    Our study explored the influence of thin- versus normal-size media models and of self-reported restrained eating behavior on women's observed snacking behavior. Fifty female undergraduates saw a set of advertisements for beauty products showing either thin or computer-altered normal-size female models, allegedly as part of a study on effective…

  3. The Design and Analysis of Salmonid Tagging Studies in the Columbia Basin; Volume XII; A Multinomial Model for Estimating Ocean Survival from Salmonid Coded Wire-Tag Data.

    Energy Technology Data Exchange (ETDEWEB)

    Ryding, Kristen E.; Skalski, John R.

    1999-06-01

    The purpose of this report is to illustrate the development of a stochastic model using coded wire-tag (CWT) release and age-at-return data, in order to regress first year ocean survival probabilities against coastal ocean conditions and climate covariates.

  4. New devices for flow measurements: Hot film and burial wire sensors, infrared imagery, liquid crystal, and piezo-electric model

    Science.gov (United States)

    Mcree, Griffith J., Jr.; Roberts, A. Sidney, Jr.

    1991-01-01

    An experimental program aimed at identifying areas in low speed aerodynamic research where infrared imaging systems can make significant contributions is discussed. Implementing a new technique, a long electrically heated wire was placed across a laminar flow. By measuring the temperature distribution along the wire with the IR imaging camera, the flow behavior was identified.

  5. Neural Network Modeling and System Simulating for the Dynamic Process of Varied Gap Pulsed GTAW with Wire Filler

    Institute of Scientific and Technical Information of China (English)

    Guangjun ZHANG; Shanben CHEN; Lin WU

    2005-01-01

    As the base of the research work on the weld shape control during pulsed gas tungsten arc welding (GTAW) with wire filler, this paper addressed the modeling of the dynamic welding process. Topside length Lt, maximum width Wt and half-length ratio Rh1 were selected to depict topside weld pool shape, and were measured on-line by vision sensing. A dynamic neural network model was constructed to predict the usually unmeasured backside width and topside height of the weld through topside shape parameters and welding parameters. The inputs of the model were the welding parameters (peak current, pulse duty ratio, welding speed, filler rate), the joint gap, the topside pool shape parameters (Lt, Wt, and Rhl), and their history values at two former pulse, a total of 24 numbers. The validating experiment results proved that the artificial neural network (ANN) model had high precision and could be used in process control. At last, with the developed dynamic model, steady and dynamic behavior was analyzed by simulation experiments, which discovered the variation rules of weld pool shape parameters under different welding parameters, and further knew well the characteristic of the welding process.

  6. Thin inclusion approach for modelling of heterogeneous conducting materials

    Energy Technology Data Exchange (ETDEWEB)

    Lavrov, Nikolay [Davenport University, 4801 Oakman Boulevard, Dearborn, MI 48126 (United States); Smirnova, Alevtina; Gorgun, Haluk; Sammes, Nigel [University of Connecticut, Department of Materials Science and Engineering, Connecticut Global Fuel Center, 44 Weaver Road, Unit 5233, Storrs, CT 06269 (United States)

    2006-04-21

    Experimental data show that heterogeneous nanostructure of solid oxide and polymer electrolyte fuel cells could be approximated as an infinite set of fiber-like or penny-shaped inclusions in a continuous medium. Inclusions can be arranged in a cluster mode and regular or random order. In the newly proposed theoretical model of nanostructured material, the most attention is paid to the small aspect ratio of structural elements as well as to some model problems of electrostatics. The proposed integral equation for electric potential caused by the charge distributed over the single circular or elliptic cylindrical conductor of finite length, as a single unit of a nanostructured material, has been asymptotically simplified for the small aspect ratio and solved numerically. The result demonstrates that surface density changes slightly in the middle part of the thin domain and has boundary layers localized near the edges. It is anticipated, that contribution of boundary layer solution to the surface density is significant and cannot be governed by classic equation for smooth linear charge. The role of the cross-section shape is also investigated. Proposed approach is sufficiently simple, robust and allows extension to either regular or irregular system of various inclusions. This approach can be used for the development of the system of conducting inclusions, which are commonly present in nanostructured materials used for solid oxide and polymer electrolyte fuel cell (PEMFC) materials. (author)

  7. Plasma chemistry in wire chambers

    Energy Technology Data Exchange (ETDEWEB)

    Wise, J.

    1990-05-01

    The phenomenology of wire chamber aging is discussed and fundamentals of proportional counters are presented. Free-radical polymerization and plasma polymerization are discussed. The chemistry of wire aging is reviewed. Similarities between wire chamber plasma (>1 atm dc-discharge) and low-pressure rf-discharge plasmas, which have been more widely studied, are suggested. Construction and use of a system to allow study of the plasma reactions occurring in wire chambers is reported. A proportional tube irradiated by an {sup 55}Fe source is used as a model wire chamber. Condensable species in the proportional tube effluent are concentrated in a cryotrap and analyzed by gas chromatography/mass spectrometry. Several different wire chamber gases (methane, argon/methane, ethane, argon/ethane, propane, argon/isobutane) are tested and their reaction products qualitatively identified. For all gases tested except those containing methane, use of hygroscopic filters to remove trace water and oxygen contaminants from the gas resulted in an increase in the average molecular weight of the products, consistent with results from low-pressure rf-discharge plasmas. It is suggested that because water and oxygen inhibit polymer growth in the gas phase that they may also reduce polymer deposition in proportional tubes and therefore retard wire aging processes. Mechanistic implications of the plasma reactions of hydrocarbons with oxygen are suggested. Unresolved issues in this work and proposals for further study are discussed.

  8. Diameter dependent polarization in ZnO/MgO disk-in-wire emitters: Multiscale modeling of optical quantum efficiency

    Science.gov (United States)

    Al-Qahtani, Saad Mubarak; Abdullah, Abdulmuin Mostafa A.; Nishat, Md. Rezaul Karim; Ahmed, Shaikh S.

    2017-03-01

    A multiscale computational study is performed to investigate how electronic structure, optical transitions, and terminal characteristics of nanostructured ZnO/MgO disk-in-wire emitters are governed by an intricate coupling of size-quantization, atomicity, and built-in structural and polarization fields. As for the models, an 8-band sp3 (with spin) atomistic tight-binding basis set was used to construct the Hamiltonian of the device in wurtzite crystal symmetry. Strain and the associated distortions of bond directions and bond lengths were modeled via the valence force-field (VFF) molecular mechanics framework. Specifically, in this work, a recently proposed ab initio based diameter-dependent model for the piezoelectric fields was implemented, which, as compared to the conventional diameter-independent model, was found to curb the influence of spontaneous (pyroelectric) polarization significantly. This particular finding is further illustrated through the calculation of electronic bandgap and localization of wavefunctions, optical emission characteristics, and the internal quantum efficiency of the device.

  9. Investigation of thermal and hot-wire chemical vapor deposition copper thin films on TiN substrates using CupraSelect as precursor.

    Science.gov (United States)

    Papadimitropoulos, G; Davazoglou, D

    2011-09-01

    Copper films were deposited on oxidized Si substrates covered with TiN using a novel chemical vapor deposition reactor in which reactions were assisted by a heated tungsten filament (hot-wire CVD, HWCVD). Liquid at room temperature hexafluoroacetylacetonate Cu(I) trimethylvinylsilane (CupraSelect) was directly injected into the reactor with the aid of a direct-liquid injection (DLI) system using N2 as carrier gas. The deposition rates of HWCVD Cu films obtained on TiN covered substrates were found to increase with filament temperature (65 and 170 degrees C were tested). The resistivities of HWCVD Cu films were found to be higher than for thermally grown films due to the possible presence of impurities into the Cu films from the incomplete dissociation of the precursor and W impurities caused by the presence of the filament. For HWCVD films grown at a filament temperature of 170 degrees C, smaller grains are formed than at 65 degrees C as shown from the taken SEM micrographs. XRD diffractograms taken on Cu films deposited on TiN could not reveal the presence of W compounds originating from the filament because the relative peak was masked by the TiN [112] peak.

  10. Finite element analysis on the wire breaking rule of 1×7IWS steel wire rope

    Directory of Open Access Journals (Sweden)

    Wenzheng Du

    2017-01-01

    Full Text Available Taking the wire rope of 1×7+IWS structure as the research object, the influences of the number of broken wires on the stress distribution under the same axial load were simulated and analysed, and it also explored the rule of wire breaking of steel wire ropes. Based on the SolidWorks software, the three-dimensional model of the wire rope was established. Importing the model into the ABAQUS, the finite element model of the steel wire rope was established. Firstly 5000 N axial tension was placed on the rope, the stress distribution was simulated and analysed, and the steel wire with the largest stress distribution was found out. Then one steel wire was truncated with the load unchanged, and the finite element simulation was carried out again, and repeated the steps several times. The results show that, with the increase of the number of broken wires, the Von-Mises stress of the wire rope increases sharply, and the stress distribution is concentrated on the rest of the unbroken wires, which brings great challenges to the safety of the wire rope.

  11. 30 CFR 75.1003 - Insulation of trolley wires, trolley feeder wires and bare signal wires; guarding of trolley...

    Science.gov (United States)

    2010-07-01

    ... wires and bare signal wires; guarding of trolley wires and trolley feeder wires. 75.1003 Section 75.1003... Insulation of trolley wires, trolley feeder wires and bare signal wires; guarding of trolley wires and trolley feeder wires. Trolley wires, trolley feeder wires, and bare signal wires shall be insulated...

  12. Modeling surface imperfections in thin films and nanostructured surfaces

    Science.gov (United States)

    Hansen, P.-E.; Madsen, J. S.; Jensen, S. A.; Madsen, M. H.; Karamehmedovic, M.

    2017-06-01

    Accurate scatterometry and ellipsometry characterization of non-perfect thin films and nanostructured surfaces are challenging. Imperfections like surface roughness make the associated modelling and inverse problem solution difficult due to the lack of knowledge about the imperfection on the surface. Combining measurement data from several instruments increases the knowledge of non-perfect surfaces. In this paper we investigate how to incorporate this knowledge of surface imperfection into inverse methods used in scatterometry and ellipsometry using the Rigorous Coupled Wave Analysis. Three classes of imperfections are examined. The imperfections are introduced as periodic structures with a super cell periods ten times larger than the simple grating period. Two classes of imperfections concern the grating and one class concern the substrate. It is shown that imperfections of a few nanometers can severely change the reflective response on silicon gratings. Inverse scatterometry analyses of gratings with imperfection using simulated data with white noise have been performed. The results show that scatterometry is a robust technology that is able to characterize grating imperfections provided that the imperfection class is known.

  13. Effects of the use of a flat wire electrode in gas metal arc welding and fuzzy logic model for the prediction of weldment shape profile

    Energy Technology Data Exchange (ETDEWEB)

    Karuthapandi, Sripriyan; Thyla, P. R. [PSG College of Technology, Coimbatore (India); Ramu, Murugan [Amrita University, Ettimadai (India)

    2017-05-15

    This paper describes the relationships between the macrostructural characteristics of weld beads and the welding parameters in Gas metal arc welding (GMAW) using a flat wire electrode. Bead-on-plate welds were produced with a flat wire electrode and different combinations of input parameters (i.e., welding current, welding speed, and flat wire electrode orientation). The macrostructural characteristics of the weld beads, namely, deposition, bead width, total bead width, reinforcement height, penetration depth, and depth of HAZ were investigated. A mapping technique was employed to measure these characteristics in various segments of the weldment zones. Results show that the use of a flat wire electrode improves the depth-to-width (D/W) ratio by 16.5 % on average compared with the D/W ratio when a regular electrode is used in GMAW. Furthermore, a fuzzy logic model was established to predict the effects of the use of a flat electrode on the weldment shape profile with varying input parameters. The predictions of the model were compared with the experimental results.

  14. Wire frame to MOVIE. BYU transfer program

    Energy Technology Data Exchange (ETDEWEB)

    Robbins, D.; Byers, L.D.; Benner, M.S.

    1982-12-01

    At SNLA, the primary computer-aided drafting tool is the Applicon Graphics System (AGS). The data base for mechanical parts on the AGS is a wire frame model. This report summarizes a method of adding surface information to the wire frame and passing this information up stream to MOVIE.BYU which is on a VAX computer and is used to produce shaded graphics pictures of the AGS wire frame model on a RAMTEK 9400 display terminal.

  15. Highly conducting phosphorous doped Nc-Si:H thin films deposited at high deposition rate by hot-wire chemical vapor deposition method.

    Science.gov (United States)

    Waman, V S; Kamble, M M; Ghosh, S S; Mayabadi, Azam; Sathe, V G; Amalnekar, D P; Pathan, H M; Jadkar, S R

    2012-11-01

    In this paper, we report the synthesis of highly conducting phosphorous doped hydrogenated nanocrystalline silicon (nc-Si:H) films at substantially low substrate temperature (200 degrees C) by hot-wire chemical vapor deposition (HW-CVD) method using pure silane (SiH4) and phosphine (PH3) gas mixture without hydrogen dilution. Structural, optical and electrical properties of these films were investigated as a function of PH3 gas-phase ratio. The characterization of these films by low-angle X-ray diffraction, Raman spectroscopy and atomic force microscopy revealed that, the incorporation of phosphorous in nc-Si:H induces an amorphization in the nc-Si:H film structure. Fourier transform infrared spectroscopy analysis indicates that hydrogen predominately incorporated in phosphorous doped n-type nc-Si:H films mainly in di-hydrogen species (Si-H2) and poly-hydrogen (Si-H2)n bonded species signifying that the films become porous, and micro-void rich. We have observed high band gap (1.97-2.37 eV) in the films, though the hydrogen content is low (< 1.4 at.%) over the entire range of PH3 gas-phase ratio studied. Under the optimum deposition conditions, phosphorous doped nc-Si:H films with high dark conductivity (sigma Dark -5.3 S/cm), low charge-carrier activation energy (E(act) - 132 meV) and high band gap (- 2.01 eV), low hydrogen content (- 0.74 at.%) were obtained at high deposition rate (12.9 angstroms/s).

  16. When thinking is beneficial and when it is not : The effects of thin and round advertising models

    NARCIS (Netherlands)

    Hafner, Michael; Trampe, Debra

    2009-01-01

    This study addresses the advertising effectiveness of round and thin models. Integrating previous findings and theories, the authors predict and find that impulsive and reflective product evaluations as responses to thin and round advertisement models diverge. Specifically, four experiments indicate

  17. When thinking is beneficial and when it is not : The effects of thin and round advertising models

    NARCIS (Netherlands)

    Häfner, M.; Trampe, D.

    2009-01-01

    This study addresses the advertising effectiveness of round and thin models. Integrating previous findings and theories, the authors predict and find that impulsive and reflective product evaluations as responses to thin and round advertisement models diverge. Specifically, four experiments indicate

  18. A two-segment model for thin filament architecture in skeletal muscle.

    Science.gov (United States)

    Gokhin, David S; Fowler, Velia M

    2013-02-01

    Correct specification of myofilament length is essential for efficient skeletal muscle contraction. The length of thin actin filaments can be explained by a novel 'two-segment' model, wherein the thin filaments consist of two concatenated segments, which are of either constant or variable length. This is in contrast to the classic 'nebulin ruler' model, which postulates that thin filaments are uniform structures, the lengths of which are dictated by nebulin. The two-segment model implicates position-specific microregulation of actin dynamics as a general principle underlying actin filament length and stability.

  19. Mathematical model for the thermal process of controlled cooling of wires and its numerical simulation

    Institute of Scientific and Technical Information of China (English)

    Hongxiang Zhu; Xiaohong Hao; Zhi Wen; Yaogen Zhang; Huqiu Chen

    2004-01-01

    The mathematical model for the thermal process of billets rolling has been established, including transporting in air and temperature-holding cover, descaling with high-pressure water, and the process of rolling and cooling in water box. The calculated data by the model have been compared with the measured data and the results show that the model is right and creditable. Based on the model, the main thermal characters of rolling line have been simulated and the influence of all the parameters on the temperature of rolling has been analyzed.

  20. Magnetoconductance of quantum wires

    Science.gov (United States)

    Ferreira, Gerson J.; Sammarco, Filipe; Egues, Carlos

    2010-03-01

    At low temperatures the conductance of a quantum wires exhibit characteristic plate-aus due to the quantization of the transverse modes [1]. In the presence of high in-plane magnetic fields these spin-split transverse modes cross. Recently, these crossings were observed experimentally [2] via measurements of the differential conductance as a function of the gate voltage and the in-plane magnetic-field. These show structures described as either anti-crossings or magnetic phase transitions. Motivated by our previous works on magnetotransport in 2DEGs via the Spin Density Functional Theory (SDFT) [3], here we propose a similar model to investigate the magnetoconductance of quantum wires. We use (i) the SDFT via the Kohn-Sham self-consistent scheme within the local spin density approximation to obtain the electronic structure and (ii) the Landauer-Buettiker formalism to calculate the conductance of a quantum wire. Our results show qualitative agreement with the data of Ref. [2]. [1] B. J. van Wees et al., Phys. Rev. Lett. 60, 848 (1988). [2] A. C. Graham et al., Phys. Rev. Lett. 100, 226804 (2008). [3] H. J. P. Freire, and J. C. Egues, Phys. Rev. Lett. 99, 026801 (2007); G. J. Ferreira, and J. Carlos Egues, J. Supercond. Nov. Mag., in press; G. J. Ferreira, H. J. P. Freire, J. Carlos Egues, submitted.

  1. Design, Modeling, Fabrication, and Evaluation of Thermoelectric Generators with Hot-Wire Chemical Vapor Deposited Polysilicon as Thermoelement Material

    Science.gov (United States)

    de Leon, Maria Theresa; Tarazona, Antulio; Chong, Harold; Kraft, Michael

    2014-11-01

    This paper presents the design, modeling, fabrication, and evaluation of thermoelectric generators (TEGs) with p-type polysilicon deposited by hot-wire chemical vapor deposition (HWCVD) as thermoelement material. A thermal model is developed based on energy balance and heat transfer equations using lumped thermal conductances. Several test structures were fabricated to allow characterization of the boron-doped polysilicon material deposited by HWCVD. The film was found to be electrically active without any post-deposition annealing. Based on the tests performed on the test structures, it is determined that the Seebeck coefficient, thermal conductivity, and electrical resistivity of the HWCVD polysilicon are 113 μV/K, 126 W/mK, and 3.58 × 10-5 Ω m, respectively. Results from laser tests performed on the fabricated TEG are in good agreement with the thermal model. The temperature values derived from the thermal model are within 2.8% of the measured temperature values. For a 1-W laser input, an open-circuit voltage and output power of 247 mV and 347 nW, respectively, were generated. This translates to a temperature difference of 63°C across the thermoelements. This paper demonstrates that HWCVD, which is a cost-effective way of producing solar cells, can also be applied in the production of TEGs. By establishing that HWCVD polysilicon can be an effective thermoelectric material, further work on developing photovoltaic-thermoelectric (PV-TE) hybrid microsystems that are cost-effective and better performing can be explored.

  2. Solar power wires based on organic photovoltaic materials.

    Science.gov (United States)

    Lee, Michael R; Eckert, Robert D; Forberich, Karen; Dennler, Gilles; Brabec, Christoph J; Gaudiana, Russell A

    2009-04-10

    Organic photovoltaics in a flexible wire format has potential advantages that are described in this paper. A wire format requires long-distance transport of current that can be achieved only with conventional metals, thus eliminating the use of transparent oxide semiconductors. A phase-separated, photovoltaic layer, comprising a conducting polymer and a fullerene derivative, is coated onto a thin metal wire. A second wire, coated with a silver film, serving as the counter electrode, is wrapped around the first wire. Both wires are encased in a transparent polymer cladding. Incident light is focused by the cladding onto to the photovoltaic layer even when it is completely shadowed by the counter electrode. Efficiency values of the wires range from 2.79% to 3.27%.

  3. Subchannel Analysis of Wire Wrapped SCWR Assembly

    OpenAIRE

    Jianqiang Shan; Henan Wang; Wei Liu; Linxing Song; Xuanxiang Chen; Yang Jiang

    2014-01-01

    Application of wire wrap spacers in SCWR can reduce pressure drop and obtain better mixing capability. As a consequence, the required coolant pumping power is decreased and the coolant temperature profile inside the fuel bundle is flattened which will obviously decrease the peak cladding temperature. The distributed resistance model for wire wrap was developed and implemented in ATHAS subchannel analysis code. The HPLWR wire wrapped assembly was analyzed. The results show that: (1) the assemb...

  4. Process for producing fine and ultrafine filament superconductor wire

    Energy Technology Data Exchange (ETDEWEB)

    Kanithi, Hem C. (15 Briar Ct., Chesire, CT 06410)

    1992-01-01

    A process for producing a superconductor wire made up of a large number of round monofilament rods is provided for, comprising assembling a multiplicity of round monofilaments inside each of a multiplicity of thin wall hexagonal tubes and then assembling a number of said thin wall hexagonal tubes within an extrusion can and subsequently consolidating, extruding and drawing the entire assembly down to the desired wire size.

  5. Analytic model of a two wire thermal sensor for flow and sound measurements

    NARCIS (Netherlands)

    Honschoten, van J.W.; Krijnen, G.J.M.; Svetovoy, V.B.; Bree, de H.E.; Elwenspoek, M.C.

    2004-01-01

    The Microflown is an acoustic sensor that measures particle velocity instead of pressure, as conventional microphones do. This paper presents an analytical model describing the physical processes that govern the behaviour of the sensor and determine its sensitivity. Forced convection by an acoustic

  6. Pinning Properties of Commercial Nb-Ti Wires Described by a 2-Components Model

    CERN Document Server

    Muzzi, L; Zignani, Chiarasole Fiamozzi; De Marzi, Gianluca; Muzzi, Luigi; Dominguez, Cesar Octavio; Bottura, Luca; Napolitano, Mathieu; Viola, Rosario; Affinito, Luigi; della Corte, Antonio; Le Naour, Sandrine

    2010-01-01

    We report on the magnetic and transport characterization of different NbTi commercial strands, carried out at variable temperature and magnetic field. From the critical current densities extracted from transport measurements and magnetization cycles we were able to calculate the normalized bulk pinning forces. The curves show good temperature scaling throughout the explored temperature range, and the reduced pinning force can be described by a simple two-components model system. The extension of the 2-components description of the pinning force to an expression for the critical current density gives a very good agreement with experimental measurements over the whole explored B, T range. The model works for all investigated samples, which are different in size, Cu:nonCu ratios, filament diameters and layouts. These results suggest that pinning mechanisms in conventional NbTi strands should be revised, since Nb-Ti composition gradients and grain boundaries seems to play a not negligible role.

  7. Design, Modeling and Optimization of a Piezoelectric Pressure Sensor based on a Thin-Film PZT Membrane Containing Nanocrystalline Powders

    National Research Council Canada - National Science Library

    Vahid Mohammadi; Mohammad Hossein Sheikhi

    2009-01-01

    ...^ thin film has been presented and then a pressure sensor based on multilayer thin-film PZT diaphragm contain of Lead Zirconate Titanate nanocrystalline powders was designed, modeled and optimized...

  8. Hard-core thinnings of germ-grain models with power-law grain sizes

    CERN Document Server

    Kuronen, Mikko

    2012-01-01

    Random sets with long-range dependence can be generated using a Boolean model with power-law grain sizes. We study thinnings of such Boolean models which have the hard-core property that no grains overlap in the resulting germ-grain model. A fundamental question is whether long-range dependence is preserved under such thinnings. To answer this question we study four natural thinnings of a Poisson germ-grain model where the grains are spheres with a regularly varying size distribution. We show that a thinning which favors large grains preserves the slow correlation decay of the original model, whereas a thinning which favors small grains does not. Our most interesting finding concerns the case where only disjoint grains are retained, which corresponds to the well-known Mat\\'ern type I thinning. In the resulting germ-grain model, typical grains have exponentially small sizes, but rather surprisingly, the long-range dependence property is still present. As a byproduct, we obtain new mechanisms for generating hom...

  9. Uniform wire segmentation algorithm of distributed interconnects

    Institute of Scientific and Technical Information of China (English)

    Yin Guoli; Lin Zhenghui

    2007-01-01

    A uniform wire segmentation algorithm for performance optimization of distributed RLC interconnects was proposed in this paper. The optimal wire length for identical segments and buffer size for buffer insertion are obtained through computation and derivation, based on a 2-pole approximation model of distributed RLC interconnect. For typical inductance value and long wires under 180nm technology, experiments show that the uniform wire segmentation technique proposed in the paper can reduce delay by about 27% ~ 56% , while requires 34%~69% less total buffer usage and thus 29% to 58% less power consumption. It is suitable for long RLC interconnect performance optimization.

  10. "Wired," yet intoxicated: modeling binge caffeine and alcohol co-consumption in the mouse.

    Science.gov (United States)

    Fritz, Brandon M; Companion, Michel; Boehm, Stephen L

    2014-08-01

    The combination of highly caffeinated "energy drinks" with alcohol (ethanol [EtOH]) has become popular among young adults and intoxication via such beverages has been associated with an elevated risk for harmful behaviors. However, there are discrepancies in the human literature regarding the effect of caffeine on alcohol intoxication, perhaps due to confounding factors such as personality type, expectancy, and history of exposure. Animal models of co-exposure are resistant to such issues; however, the consequences of voluntary co-consumption have been largely ignored in the animal literature. The primary goal of this work was to characterize a mouse model of binge caffeine and EtOH co-consumption employing the limited access "Drinking-in-the-Dark" (DID) paradigm. Caffeine was added to a 20% alcohol solution via DID. Alcohol/caffeine intake, locomotor behavior, ataxia, anxiety-like behavior, and cognitive function were evaluated as a consequence of co-consumption in adult male C57BL/6J mice. Caffeine did not substantially alter binge alcohol intake or resultant blood EtOH concentrations (BECs), nor did it alter alcohol's anxiolytic effects on the elevated plus maze or cognitive-interfering effects in a novel object-recognition task. However, no evidence of alcohol-induced sedation was observed in co-consumption groups that instead demonstrated a highly stimulated state similar to that of caffeine alone. The addition of caffeine was also found to mitigate alcohol-induced ataxia. Taken together, our mouse model indicates that binge co-consumption of caffeine and alcohol produces a stimulated, less ataxic and anxious, as well as cognitively altered state; a state that could be of great public health concern. These results appear to resemble the colloquially identified "wide awake drunk" state that individuals seek via consumption of such beverages. This self-administration model therefore offers the capacity for translationally valid explorations of the

  11. Wire bonding in microelectronics

    CERN Document Server

    Harman, George G

    2010-01-01

    Wire Bonding in Microelectronics, Third Edition, has been thoroughly revised to help you meet the challenges of today's small-scale and fine-pitch microelectronics. This authoritative guide covers every aspect of designing, manufacturing, and evaluating wire bonds engineered with cutting-edge techniques. In addition to gaining a full grasp of bonding technology, you'll learn how to create reliable bonds at exceedingly high yields, test wire bonds, solve common bonding problems, implement molecular cleaning methods, and much more. Coverage includes: Ultrasonic bonding systems and technologies, including high-frequency systems Bonding wire metallurgy and characteristics, including copper wire Wire bond testing Gold-aluminum intermetallic compounds and other interface reactions Gold and nickel-based bond pad plating materials and problems Cleaning to improve bondability and reliability Mechanical problems in wire bonding High-yield, fine-pitch, specialized-looping, soft-substrate, and extreme-temperature wire bo...

  12. Wire harness twisting aid

    Science.gov (United States)

    Casey, E. J.; Commadore, C. C.; Ingles, M. E.

    1980-01-01

    Long wire bundles twist into uniform spiral harnesses with help of simple apparatus. Wires pass through spacers and through hand-held tool with hole for each wire. Ends are attached to low speed bench motor. As motor turns, operator moves hand tool away forming smooth twists in wires between motor and tool. Technique produces harnesses that generate less radio-frequency interference than do irregularly twisted cables.

  13. Addressing water vaporization in the vicinity of an exploding wire

    Science.gov (United States)

    Grinenko, A.; Gurovich, V. Tz.; Krasik, Ya. E.; Dolinsky, Yu.

    2006-12-01

    The phase state of thin (˜1μm) layer of water adjacent to the surface of rapidly heated thin wire 100±50μm in radius is analyzed by computer hydrodynamic calculation. It is shown that when heating of a wire to a temperature of 420°C is achieved in less than ˜500ns, the trajectory of the phase state is contained in the liquid part of the phase diagram. This suggests additional proof of and an explanation for the absence of shunting plasma discharge in fast underwater electrical wire explosions.

  14. Using atomistic simulations to model cadmium telluride thin film growth

    Science.gov (United States)

    Yu, Miao; Kenny, Steven D.

    2016-03-01

    Cadmium telluride (CdTe) is an excellent material for low-cost, high efficiency thin film solar cells. It is important to conduct research on how defects are formed during the growth process, since defects lower the efficiency of solar cells. In this work we use computer simulation to predict the growth of a sputter deposited CdTe thin film. On-the-fly kinetic Monte Carlo technique is used to simulate the CdTe thin film growth on the (1 1 1) surfaces. The results show that on the (1 1 1) surfaces the growth mechanisms on surfaces which are terminated by Cd or Te are quite different, regardless of the deposition energy (0.1∼ 10 eV). On the Te-terminated (1 1 1) surface the deposited clusters first form a single mixed species layer, then the Te atoms in the mixed layer moved up to form a new layer. Whilst on the Cd-terminated (1 1 1) surface the new Cd and Te layers are formed at the same time. Such differences are probably caused by stronger bonding between ad-atoms and surface atoms on the Te layer than on the Cd layer.

  15. Controlled electromigration and oxidation of free-standing copper wires

    Science.gov (United States)

    Hauser, J. S.; Schwichtenberg, J.; Marz, M.; Sürgers, C.; Seiler, A.; Gerhards, U.; Messerschmidt, F.; Hensel, A.; Dittmeyer, R.; Löhneysen, H. v.; Hoffmann-Vogel, R.

    2016-12-01

    We have studied controlled electromigration (EM) in free-standing copper wires. Besides electrical characterization by voltage-current measurements, structural analyses have been performed by means of scanning electron microscopy and cross-sectional microprobe measurements. We have found that oxidation during the EM in air stabilizes the free-standing wire against uncontrolled blowing, making it possible to thin the conductive part of the wire down to a conductance of a few conductance quanta G_0=2e^2{/}h. The decisive influence of oxidation by air on the EM process was confirmed by control experiments performed under ultra-high vacuum conditions. In line with these findings, free-standing Au wires were difficult to thin down reproducibly to a conductance of a few G_0. Estimates of the local temperature in the free-standing wire are obtained from finite element method calculations.

  16. Gold Incorporated Mesoporous Silica Thin Film Model Surface as a Robust SERS and Catalytically Active Substrate

    Directory of Open Access Journals (Sweden)

    Anandakumari Chandrasekharan Sunil Sekhar

    2016-05-01

    Full Text Available Ultra-small gold nanoparticles incorporated in mesoporous silica thin films with accessible pore channels perpendicular to the substrate are prepared by a modified sol-gel method. The simple and easy spin coating technique is applied here to make homogeneous thin films. The surface characterization using FESEM shows crack-free films with a perpendicular pore arrangement. The applicability of these thin films as catalysts as well as a robust SERS active substrate for model catalysis study is tested. Compared to bare silica film our gold incorporated silica, GSM-23F gave an enhancement factor of 103 for RhB with a laser source 633 nm. The reduction reaction of p-nitrophenol with sodium borohydride from our thin films shows a decrease in peak intensity corresponding to –NO2 group as time proceeds, confirming the catalytic activity. Such model surfaces can potentially bridge the material gap between a real catalytic system and surface science studies.

  17. Effect of Gas Phase Heat Sink on Suppression of Opposed Flow Flame Spread over Thin Solid Fuels in Microgravity Environment

    Directory of Open Access Journals (Sweden)

    Vinayak Malhotra

    2012-01-01

    Full Text Available A two-dimensional numerical model of opposed flow flame spread over thin solid fuel is formulated and modeled to study the effect of gas phase heat sink (a wire mesh placed parallel to the fuel surface on the flame-spread rate and flame extinction. The work focuses on the performance of the wire mesh in microgravity environment at an oxygen concentration 21%. The simulations were carried out for various mesh parameters (wire diameter, “” and number of wires per unit length, “” and mesh distance perpendicular to fuel surface “”. Simulations show that wire mesh is effective in reducing flame-spread rate when placed at distance less than flame width (which is about 1 cm. Mesh wire diameter is determined not to have major influence on heat transfer. However, smaller wire diameter is preferred for better aerodynamics and for increasing heat transfer surface area (here prescribed by parameter “”. Flame suppression exhibits stronger dependence on number of wires per unit length; however, it is relatively insensitive to number of wires per unit length beyond certain value (here 20 cm−1.

  18. Effect of a dielectric coating on terahertz surface plasmon polaritons on metal wires

    NARCIS (Netherlands)

    Van der Valk, N.C.J.; Planken, P.C.M.

    2005-01-01

    The authors present measurements and calculations on the effect of thin dielectric coatings on the propagation of terahertz pulses along the surface of metal wires. Our measurements show that propagation over only a few centimeters of wire having a thin dielectric coating, strongly distorts the tera

  19. Microphysical Parameterization of Arctic Diamond Dust, Ice Fog, and Thin Stratus for Climate Models

    National Research Council Canada - National Science Library

    Girard, Eric; Blanchet, Jean-Pierre

    2001-01-01

    ... and entrainment are weak, like ice fogs, thin stratus, and diamond dust. The parameterization is tested into the Local Climate Model (LCM), which is the single column version of the Northern Aerosol Regional Climate Model (NARCM). NARCM is a regional model with an explicit representation of the aerosol physics and with the physics package of the Canadian Climat...

  20. Modeling of Stress Development During Thermal Damage Healing in Fiber-reinforced Composite Materials Containing Embedded Shape Memory Alloy Wires

    NARCIS (Netherlands)

    Bor, Teunis Cornelis; Warnet, Laurent; Akkerman, Remko; de Boer, Andries

    2010-01-01

    Fiber-reinforced composite materials are susceptible to damage development through matrix cracking and delamination. This article concerns the use of shape memory alloy (SMA) wires embedded in a composite material to support healing of damage through a local heat treatment. The composite material

  1. Modeling of Stress Development During Thermal Damage Healing in Fiber-reinforced Composite Materials Containing Embedded Shape Memory Alloy Wires

    NARCIS (Netherlands)

    Bor, T.C.; Warnet, L.; Akkerman, R.; Boer, de A.

    2010-01-01

    Fiber-reinforced composite materials are susceptible to damage development through matrix cracking and delamination. This article concerns the use of shape memory alloy (SMA) wires embedded in a composite material to support healing of damage through a local heat treatment. The composite material co

  2. Numerical Modeling of Melting Process of Thin Metal Films Subjected to the Short Laser Pulse

    Directory of Open Access Journals (Sweden)

    E. Majchrzak

    2012-12-01

    Full Text Available Thin metal film subjected to a short-pulse laser heating is considered. The parabolic two-temperature model describing the temporal and spatial evolution of the lattice and electrons temperatures is discussed and the melting process of thin layer is taken into account. At the stage of numerical computations the finite difference method is used. In the final part of the paper the examples of computations are shown.

  3. Experimental research on engineering geological mechanical model of strip mining below thin bedrock

    Energy Technology Data Exchange (ETDEWEB)

    Yang, W.; Sui, W. [CUMT, Xuzhou (China). School of Resources and Earth Science

    2004-03-15

    With respect to thin bedrock strata found in Taiping coal mining area of Yanzhou, mechanism and controlling factors of overlying strata and ground movement deformation induced by strip mining under the condition of thin bedrock were studied by means of engineering geological model test. The destruction process, forms, and ranges of overlying strata and the rules of ground movement were revealed, providing a theoretical basis for engineering practice. 10 refs., 3 figs.

  4. Effect of wire shape on wire array discharge

    Energy Technology Data Exchange (ETDEWEB)

    Shimomura, N.; Tanaka, Y.; Yushita, Y.; Nagata, M. [University of Tokushima, Department of Electrical and Electronic Engineering, Tokushima (Japan); Teramoto, Y.; Katsuki, S.; Akiyama, H. [Kumamoto University, Department of Electrical and Computer Engineering, Kumamoto (Japan)

    2001-09-01

    Although considerable investigations have been reported on z-pinches to achieve nuclear fusion, little attention has been given from the point of view of how a wire array consisting of many parallel wires explodes. Instability existing in the wire array discharge has been shown. In this paper, the effect of wire shape in the wire array on unstable behavior of the wire array discharge is represented by numerical analysis. The claws on the wire formed in installation of wire may cause uniform current distribution on wire array. The effect of error of wire diameter in production is computed by Monte Carlo Method. (author)

  5. PS wire chamber

    CERN Multimedia

    1970-01-01

    A wire chamber used at CERN's Proton Synchrotron accelerator in the 1970s. Multi-wire detectors contain layers of positively and negatively charged wires enclosed in a chamber full of gas. A charged particle passing through the chamber knocks negatively charged electrons out of atoms in the gas, leaving behind positive ions. The electrons are pulled towards the positively charged wires. They collide with other atoms on the way, producing an avalanche of electrons and ions. The movement of these electrons and ions induces an electric pulse in the wires which is collected by fast electronics. The size of the pulse is proportional to the energy loss of the original particle.

  6. Mechanical optimisation of a high-precision fast wire scanner at CERN

    CERN Document Server

    Samuelsson, Sebastian; Veness, Raymond

    Wire scanners are instruments used to measure the transverse beam prole in particle accelerators by passing a thin wire through the particle beam. To avoid the issues of vacuum leakage through the bellows and wire failure related to current designs of wire scanners, a new concept for a wire scanner has been developed at CERN. This design has all moving parts inside the beam vacuum and has a nominal wire scanning speed of 20 m/s. The demands on the design associated with this together with the high precision requirements create a need for\

  7. Integrated Electrical Wire Insulation Repair System

    Science.gov (United States)

    Williams, Martha; Jolley, Scott; Gibson, Tracy; Parks, Steven

    2013-01-01

    An integrated system tool will allow a technician to easily and quickly repair damaged high-performance electrical wire insulation in the field. Low-melt polyimides have been developed that can be processed into thin films that work well in the repair of damaged polyimide or fluoropolymer insulated electrical wiring. Such thin films can be used in wire insulation repairs by affixing a film of this low-melt polyimide to the damaged wire, and heating the film to effect melting, flow, and cure of the film. The resulting repair is robust, lightweight, and small in volume. The heating of this repair film is accomplished with the use of a common electrical soldering tool that has been modified with a special head or tip that can accommodate the size of wire being repaired. This repair method can furthermore be simplified for the repair technician by providing replaceable or disposable soldering tool heads that have repair film already "loaded" and ready for use. The soldering tool heating device can also be equipped with a battery power supply that will allow its use in areas where plug-in current is not available

  8. Habitat and spatial thinning improve the Maxent models performed with incomplete data

    Science.gov (United States)

    Kiedrzyński, Marcin; Zielińska, Katarzyna M.; Rewicz, Agnieszka; Kiedrzyńska, Edyta

    2017-06-01

    Species distribution models need adequate sets of data, particularly in the case of range-restricted species. The problem faced in the modeling of rare species is twofold: a small sample size and the occurrence of sampling biases. The present analysis combines spatial- and habitat-thinning approaches to improve maximum entropy models based on geographically incomplete data of relict and subendemic Festuca amethystina L. grass on Polish territory. The results show that models based on strongly incomplete historic data did not predict the occurrence of all important areas where the species was found in the following decades. However, the introduction of species-specific thinning allows for more precise prediction of the species range, i.e., the detection of suitable areas on a more local scale. The introduction of habitat thinning caused the diversity of important predictors in model to increase, but spatial thinning decreased the number of significant predictors and made interpretation easier. Additionally, a combination of thinning techniques allowed significant improvements to be made to the model predictions after the experimental addition of a lower number of localities to regions which had previously been poorly recognized. It can be concluded that in the case of incomplete data, the above corrections allow the true range of the species to be predicted after the discovery of a lower number and relatively dispersed new localities.

  9. A Hierarchical Bayesian Model to Predict Self-Thinning Line for Chinese Fir in Southern China.

    Directory of Open Access Journals (Sweden)

    Xiongqing Zhang

    Full Text Available Self-thinning is a dynamic equilibrium between forest growth and mortality at full site occupancy. Parameters of the self-thinning lines are often confounded by differences across various stand and site conditions. For overcoming the problem of hierarchical and repeated measures, we used hierarchical Bayesian method to estimate the self-thinning line. The results showed that the self-thinning line for Chinese fir (Cunninghamia lanceolata (Lamb.Hook. plantations was not sensitive to the initial planting density. The uncertainty of model predictions was mostly due to within-subject variability. The simulation precision of hierarchical Bayesian method was better than that of stochastic frontier function (SFF. Hierarchical Bayesian method provided a reasonable explanation of the impact of other variables (site quality, soil type, aspect, etc. on self-thinning line, which gave us the posterior distribution of parameters of self-thinning line. The research of self-thinning relationship could be benefit from the use of hierarchical Bayesian method.

  10. Improving the thin-disk models of circumstellar disk evolution. The 2+1-dimensional model

    Science.gov (United States)

    Vorobyov, Eduard I.; Pavlyuchenkov, Yaroslav N.

    2017-09-01

    Context. Circumstellar disks of gas and dust are naturally formed from contracting pre-stellar molecular cores during the star formation process. To study various dynamical and chemical processes that take place in circumstellar disks prior to their dissipation and transition to debris disks, the appropriate numerical models capable of studying the long-term disk chemodynamical evolution are required. Aims: We improve the frequently used 2D hydrodynamical model for disk evolution in the thin-disk limit by employing a better calculation of the disk thermal balance and adding a reconstruction of the disk vertical structure. Together with the hydrodynamical processes, the thermal evolution is of great importance since it influences the strength of gravitational instability and the chemical evolution of the disk. Methods: We present a new 2+1-dimensional numerical hydrodynamics model of circumstellar disk evolution, where the thin-disk model is complemented with the procedure for calculating the vertical distributions of gas volume density and temperature in the disk. The reconstruction of the disk vertical structure is performed at every time step via the solution of the time-dependent radiative transfer equations coupled to the equation of the vertical hydrostatic equilibrium. Results: We perform a detailed comparison between circumstellar disks produced with our previous 2D model and with the improved 2+1D approach. The structure and evolution of resulting disks, including the differences in temperatures, densities, disk masses, and protostellar accretion rates, are discussed in detail. Conclusions: The new 2+1D model yields systematically colder disks, while the in-falling parental clouds are warmer. Both effects act to increase the strength of disk gravitational instability and, as a result, the number of gravitationally bound fragments that form in the disk via gravitational fragmentation as compared to the purely 2D thin-disk simulations with a simplified

  11. Study of viscous flow during thin film polymer coating and drawing of continuum

    OpenAIRE

    Akter, Suraiya

    1997-01-01

    This study involves both theoretical and experimental thin polymer coating on wire as well as drawing of wire by hydrodynamic pressure technique. Hydrodynamic pressure technique is a relatively new and innovative technique for wire drawing and thin polymer coating. The wire submerged in polymer melt inside the pressure unit of different geometry, when pulled developed hydrodynamic pressure in the melt. This pressure is largely responsible for wire drawing or coating. Most of the theoretic...

  12. A new design of wire locators for drift tubes

    CERN Document Server

    Ilgner, C

    2004-01-01

    Every position-sensitive wire detector needs to solve the problem of wire positioning with a defined accuracy all over its sensitive volume. In particular, thin-walled drift tubes ("straws"), which are currently being attached to large detector units of several tens of square meters of surface, need to be equipped with wire locators along their signal wires. A wire locator has been developed together with an insertion device, especially for medium-sized drift tube systems, which significantly reduces the production time and avoids the danger of applying epoxy glue to the signal wire. The wire locator is being inserted in one single time-saving production step together with the signal wire itself. The proposed design is being compared to the rigid wire locators in use in the COMPASS straw tracking system at CERN. The investigation comprises both wire- centering capability and influence on the efficiency of adjacent detector regions, demonstrating the competitive performance of the proposed new system. Its suff...

  13. A model for thin layer formation by delayed particle settling at sharp density gradients

    Science.gov (United States)

    Prairie, Jennifer C.; White, Brian L.

    2017-02-01

    Thin layers - regions where plankton or particles accumulate vertically on scales of a few meters or less - are common in coastal waters, and have important implications for both trophic dynamics and carbon cycling. These features can form by a variety of biological and physical mechanisms, including localized growth, shear-thinning, and directed swimming. An additional mechanism may result in the formation of thin layers of marine aggregates, which have been shown to decrease their settling velocity when passing through sharp density gradients, a behavior termed delayed settling. Here, we apply a simple vertical advection-diffusion model to predict the properties of aggregate thin layers formed by this process. We assume a constant vertical flux of particles from the surface, which is parameterized by observations from laboratory experiments with marine aggregates. The formation, maintenance, and shape of the layers are described in relation to non-dimensional numbers that depend on environmental conditions and particle settling properties. In particular, model results demonstrate layer intensity and sharpness both increase with higher Péclet number (Pe), that is, under conditions with weaker mixing relative to layer formation. Similarly, more intense and sharper layers are found when the delayed settling behavior of aggregates is characterized by a lower velocity minimum. The model also predicts layers that are vertically asymmetric and highly "peaky" when compared with a Gaussian distribution, features often seen in thin layers in natural environments. Lastly, by comparing model predictions with observations of thin layers in the field, we are able to gain some insight into the applicability of delayed settling as a thin layer formation mechanism in different environmental conditions.

  14. Modeling flux pinning in thin undoped and BazRo3-doped YBCO films

    DEFF Research Database (Denmark)

    Paturi, P.; Irjala, M.; Huhtinen, H.

    2009-01-01

    A simple model based on distributions of twin boundaries, dislocations, and BaZrO3 nanorods is presented to describe the Jc properties of undoped and BaZrO3 (BZO)-doped YBa2Cu3Ox thin films. The model accurately describes the shape of Jc(B,T) curves of the films, when the pinning site distributions...

  15. A mass transfer model of ethanol emission from thin layers of corn silage

    Science.gov (United States)

    A mass transfer model of ethanol emission from thin layers of corn silage was developed and validated. The model was developed based on data from wind tunnel experiments conducted at different temperatures and air velocities. Multiple regression analysis was used to derive an equation that related t...

  16. Current-voltage relation for thin tunnel barriers: Parabolic barrier model

    DEFF Research Database (Denmark)

    Hansen, Kim; Brandbyge, Mads

    2004-01-01

    We derive a simple analytic result for the current-voltage curve for tunneling of electrons through a thin uniform insulating layer modeled by a parabolic barrier. Our model, which goes beyond the Wentzel–Kramers–Brillouin approximation, is applicable also in the limit of highly transparant barri...

  17. Fingerprint matching by thin-plate spline modelling of elastic deformations

    NARCIS (Netherlands)

    Bazen, Asker M.; Gerez, Sabih H.

    2003-01-01

    This paper presents a novel minutiae matching method that describes elastic distortions in fingerprints by means of a thin-plate spline model, which is estimated using a local and a global matching stage. After registration of the fingerprints according to the estimated model, the number of matching

  18. 30 CFR 77.1802 - Insulation of trolley wires, trolley feeder wires and bare signal wires; guarding of trolley...

    Science.gov (United States)

    2010-07-01

    ... wires and bare signal wires; guarding of trolley wires and trolley feeder wires. 77.1802 Section 77.1802... Wires and Trolley Feeder Wires § 77.1802 Insulation of trolley wires, trolley feeder wires and bare..., and bare signal wires shall be adequately guarded: (a) At all points where men are required to work or...

  19. Limiting oxygen concentration for extinction of upward spreading flames over inclined thin polyethylene-insulated NiCr electrical wires with opposed-flow under normal- and micro-gravity

    KAUST Repository

    Hu, Longhua

    2016-10-02

    Materials, such as electrical wire, used in spacecraft must pass stringent fire safety standards. Tests for such standards are typically performed under normal gravity conditions and then extended to applications under microgravity conditions. The experiments reported here used polyethylene (PE)-insulated (thickness of 0.15 mm) Nichrome (NiCr)-core (diameter of 0.5 mm) electrical wires. Limiting oxygen concentrations (LOC) at extinction were measured for upward spreading flame at various forced opposed-flow (downward) speeds (0−25 cm/s) at several inclination angles (0−75°) under normal gravity conditions. The differences from those previously obtained under microgravity conditions were quantified and correlated to provide a reference for the development of fire safety test standards for electrical wires to be used in space exploration. It was found that as the opposed-flow speed increased for a specified inclination angle (except the horizontal case), LOC first increased, then decreased and finally increased again. The first local maximum of this LOC variation corresponded to a critical forced flow speed resulted from the change in flame spread pattern from concurrent to counter-current type. This critical forced flow speed correlated well with the buoyancy-induced flow speed component in the wire\\'s direction when the flame base width along the wire was used as a characteristic length scale. LOC was generally higher under the normal gravity than under the microgravity and the difference between the two decreased as the opposed-flow speed increases, following a reasonably linear trend at relatively higher flow speeds (over 10 cm/s). The decrease in the difference in LOC under normal- and microgravity conditions as the opposed-flow speed increases correlated well with the gravity acceleration component in the wire\\'s direction, providing a measure to extend LOC determined by the tests under normal gravity conditions (at various inclination angles and opposed

  20. A stochastic model of solid state thin film deposition: Application to chalcopyrite growth

    Directory of Open Access Journals (Sweden)

    Robert J. Lovelett

    2016-04-01

    Full Text Available Developing high fidelity quantitative models of solid state reaction systems can be challenging, especially in deposition systems where, in addition to the multiple competing processes occurring simultaneously, the solid interacts with its atmosphere. In this work, we develop a model for the growth of a thin solid film where species from the atmosphere adsorb, diffuse, and react with the film. The model is mesoscale and describes an entire film with thickness on the order of microns. Because it is stochastic, the model allows us to examine inhomogeneities and agglomerations that would be impossible to characterize with deterministic methods. We demonstrate the modeling approach with the example of chalcopyrite Cu(InGa(SeS2 thin film growth via precursor reaction, which is a common industrial method for fabricating thin film photovoltaic modules. The model is used to understand how and why through-film variation in the composition of Cu(InGa(SeS2 thin films arises and persists. We believe that the model will be valuable as an effective quantitative description of many other materials systems used in semiconductors, energy storage, and other fast-growing industries.

  1. Optical bandgap modeling of thermal annealed ZnO:Ga thin films using neural networks

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Chang Eun; Moon, Pyung; Yun, Ilgu [School of Electrical and Electronic Engineering, Yonsei University, 262 Seongsanno, Seodaemoon-gu, Seoul 120-749 (Korea); Kim, Sungyeon; Myoung, Jae-Min [Department of Materials Science and Engineering, Yonsei University, 262 Seongsanno, Seodaemoon-gu, Seoul 120-749 (Korea); Jang, Hyeon Woo; Bang, Jungsik [LG Chem, Ltd., Research Park, 104-1 Moonji-Dong, Yuseng-Gu, Daejeon 305-380 (Korea)

    2010-07-15

    In this paper, the thermal annealing process modeling for the optical bandgap of ZnO:Ga thin films for transparent conductive oxide was presented using neural network (NNets) based on error backpropagation (BPNN) algorithm and multilayer perceptron (MLP). The thermal annealing process of ZnO:Ga thin films were analyzed by general factorial experimental design. The annealing temperature and film thickness were considered as input factors. To model the nonlinear annealing process, 6 experiments were trained by BPNN which has 2-4-1 structures and 2 additional samples were experimented to verify the predicted models. The output response model on optical bandgap and carrier concentration of ZnO:Ga thin films trained by BPNN was represented by surface plot of response surface model. Based on the modeling results, NNets can provide sufficient correspondence between the predicted output values and the measured. The optical bandgap variation of ZnO:Ga thin films by annealing is due to increased carrier concentration and explained by Burstein-Moss effect. The thermal annealing process is nonlinear and complex but the output response can be predicted by the NNets model. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  2. A model for spalling of HPC thin plates exposed to fire

    DEFF Research Database (Denmark)

    Hulin, Thomas; Hodicky, Kamil; Schmidt, Jacob Wittrup;

    2013-01-01

    to disclose the temperature distributions during the test. A non-linear coupled model for time dependent heat and mass transfer in concrete thin plates was used for temperature and pore pressure computations. Results from modelling and tests are compared and discussed. Moisture content was found......An experimental program was carried out to investigate the behaviour of high performance concrete (HPC) thin plates in fire for use in sandwich panels. To reveal the influence of moisture two initial moisture contents for wet and dry samples were examined. In addition, two thicknesses were used...

  3. Effect of exposure to photographs of thin models on self-consciousness in female college students.

    Science.gov (United States)

    Wegner, B S; Hartmann, A M; Geist, C R

    2000-06-01

    The purpose of this study was to assess the immediate influence of brief exposure to images taken from print media on the general self-consciousness and body self-consciousness of 67 college women. After viewing photographs of either thin female models or control photographs, the women completed the Self-consciousness Scale and the Body Self-consciousness Questionnaire. Although alpha was .45, the college women who looked at images of thin female models gave immediate ratings significantly (p Self-consciousness and Body Self-consciousness than those who looked at control images.

  4. Wire + Arc Additive Manufacturing

    OpenAIRE

    Williams, Stewart W.; Martina, Filomeno; Addison, Adrian C.; Ding, Jialuo; Pardal, Goncalo; Colegrove, Paul A.

    2016-01-01

    Depositing large components (>10 kg) in titanium, aluminium, steel and other metals is possible using Wire + Arc Additive Manufacturing. This technology adopts arc welding tools and wire as feedstock for additive manufacturing purposes. High deposition rates, low material and equipment costs, and good structural integrity make Wire+Arc Additive Manufacturing a suitable candidate for replacing the current method of manufacturing from solid billets or large forgings, especially with regards to ...

  5. Electronic structure and carrier transfer in B-DNA monomer polymers and dimer polymers: Stationary and time-dependent aspects of wire model vs. extended ladder model

    CERN Document Server

    Lambropoulos, K; Morphis, A; Kaklamanis, K; Lopp, R; Theodorakou, M; Tassi, M; Simserides, C

    2016-01-01

    We employ two Tight-Binding (TB) approaches to study the electronic structure and hole or electron transfer in B-DNA monomer polymers and dimer polymers made up of $N$ monomers (base pairs): (I) at the base-pair level, using the on-site energies of base pairs and the hopping integrals between successive base pairs, i.e., a wire model and (II) at the single-base level, using the on-site energies of the bases and the hopping integrals between neighboring bases, i.e., an \\textit{extended} ladder model since we also include diagonal hoppings. We solve a system of $MD$ ("matrix dimension") coupled equations [(I) $MD$ = $N$, (II) $MD$ = $2N$] for the time-independent problem, and a system of $MD$ coupled $1^\\text{st}$ order differential equations for the time-dependent problem. We study the HOMO and the LUMO eigenspectra, the occupation probabilities, the Density of States (DOS) and the HOMO-LUMO gap as well as the mean over time probabilities to find the carrier at each site [(I) base pair or (II) base)], the Four...

  6. Charpak hemispherical wire chamber

    CERN Multimedia

    1970-01-01

    pieces. Mesures are of the largest one. Multi-wire detectors contain layers of positively and negatively charged wires enclosed in a chamber full of gas. A charged particle passing through the chamber knocks negatively charged electrons out of atoms in the gas, leaving behind positive ions. The electrons are pulled towards the positively charged wires. They collide with other atoms on the way, producing an avalanche of electrons and ions. The movement of these electrons and ions induces an electric pulse in the wires which is collected by fast electronics. The size of the pulse is proportional to the energy loss of the original particle.

  7. Photovoltaic Wire Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This Small Business Innovation Research Phase I project will investigate a new architecture for photovoltaic devices based on nanotechnology: photovoltaic wire. The...

  8. On-Wire Lithography

    National Research Council Canada - National Science Library

    Lidong Qin; Sungho Park; Ling Huang; Chad A. Mirkin

    2005-01-01

    .... This procedure, termed on-wire lithography, combines advances in template-directed synthesis of nanowires with electrochemical deposition and wet-chemical etching and allows routine fabrication...

  9. 1998 wire development workshop proceedings

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-04-01

    This report consists of vugraphs of the presentations at the conference. The conference was divided into the following sessions: (1) First Generation Wire Development: Status and Issues; (2) First Generation Wire in Pre-Commercial Prototypes; (3) Second Generation Wire Development: Private Sector Progress and Issues; (4) Second Generation Wire Development: Federal Laboratories; and (5) Fundamental Research Issues for HTS Wire Development.

  10. Breakage of Curved Copper Wires Caused by High Impulse Current of Lightning

    Science.gov (United States)

    Hu, Xiaobo; Inaba, Tsuginori; Kindersberger, Josef

    In past studies, after thin straight copper wires of 0.1mmφ were exposed to an impulse current, their temperature rose; they melted according to the specific pre-arcing Joule integral in an adiabatic state. However, in this study, we confirmed that thick straight copper wires of 1mmφ and over it were broken in a solid state before melting The effect of physical damage on copper wire performance was confirmed. The test data suggest that ohmic heating is the main reason for thin (less than 1mmφ) copper wire breakage in the experiments. However, the magnetic force and skin effect are primarily responsible for breaking thick copper wires rather than thermal failure, as previously thought. And the thicker the copper wires diameter was, the more noticeable the magnetic force and skin effect were. Then the impulse current was impressed through curved copper wires from 0.3mmφ to 2.0mmφ. Because of different breakage mechanism for thin and thick copper wires, the current-carrying capability of thin curved copper wires did not change comparing to that of straight ones. However, the current-carrying capability of thick copper wires greatly decreased when they were curved.

  11. Current distribution effects in AC impedance spectroscopy of electroceramic point contact and thin film model electrodes

    DEFF Research Database (Denmark)

    Nielsen, Jimmi; Jacobsen, Torben

    2010-01-01

    The Finite-Element-Method (FEM) was used for the simulations of the effect of a changing current distribution during AC impedance spectrum recording on electroceramic point contact and thin film model electrodes. For pure electronic conducting point contact electrodes the transition from the prim......The Finite-Element-Method (FEM) was used for the simulations of the effect of a changing current distribution during AC impedance spectrum recording on electroceramic point contact and thin film model electrodes. For pure electronic conducting point contact electrodes the transition from...... regarding its significance is provided. The associated characteristic impedance spectrum shape change is simulated and its origin discussed. Furthermore, the characteristic shape of impedance spectra of thin electroceramic film electrodes with lateral ohmic resistance is studied as a function...

  12. Dynamic response of thin-walled structures by variable kinematic one-dimensional models

    Science.gov (United States)

    Carrera, E.; Varello, A.

    2012-11-01

    This paper investigates the accuracy capabilities of using variable kinematic modeling in compact and thin-walled beam-like structures with dynamic loadings. Carrera Unified Formulation (CUF) is employed to introduce refined one-dimensional (1D) models with a variable order of expansion for the displacement unknowns over the beam cross-section. Classical Euler-Bernoulli and Timoshenko beam theories are obtained as particular cases of these variable kinematic models while a higher order expansion permits the detection of in-plane cross-section deformation, since it leads to shell-like solutions. Finite element (FE) method is used to provide numerical results and the Newmark method is implemented as a time integration scheme. Some assessments with closed form solutions are discussed and comparisons with shell-type results obtained with commercial FE software are made. Further analyses address both compact and thin-walled cross-sections. In particular, the case of a deformable thin-walled cylinder loaded by time-dependent internal forces is discussed. The results clearly show that finite elements which are formulated in the CUF framework do not introduce additional numerical problems with respect to classical beam theories. Comparisons with elasticity solutions prove that the present 1D CUF model offers an accuracy in analyzing thin-walled structures which is typical of shell or three-dimensional models with a remarkable reduction in the computational cost required.

  13. Numerical modeling of the thermal-hydraulic behavior of wire-on-tube condensers operating with HFC-134a using homogeneous equilibrium model: evaluation of some void fraction correlations

    Science.gov (United States)

    Guzella, Matheus dos Santos; Cabezas-Gómez, Luben; da Silva, José Antônio; Maia, Cristiana Brasil; Hanriot, Sérgio de Morais

    2016-02-01

    This study presents a numerical evaluation of the influence of some void fraction correlations over the thermal-hydraulic behavior of wire-on-tube condensers operating with HFC-134a. The numerical model is based on finite volume method considering the homogeneous equilibrium model. Empirical correlations are applied to provide closure relations. Results show that the choice of void fraction correlation influences the refrigerant charge and pressure drop calculations, while no influences the heat transfer rate.

  14. Modeling and optimization of white paint back reflectors for thin-film silicon solar cells

    NARCIS (Netherlands)

    Lipovšek, B.; Krč, J.; Isabella, O.; Zeman, M.; Topič, M.

    2010-01-01

    Diffusive dielectric materials such as white paint have been demonstrated as effective back reflectors in the photovoltaic technology. In this work, a one-dimensional (1D) optical modeling approach for simulation of white paint films is developed and implemented in a 1D optical simulator for thin-fi

  15. Finite Element Modelling of Bends and Creases during Folding Ultra Thin Stainless Steel Foils

    NARCIS (Netherlands)

    Datta, K.; Akagi, H.; Geijselaers, H.J.M.; Huetink, J.

    2003-01-01

    Finite Element Modelling of an ultra thin foil of SUS 304 stainless steel is carried out. These foils are 20 mm and below in thickness. The development of stresses and strains during folding of these foils is studied. The objective of this study is to induce qualities of paper in the foils of stainl

  16. Modeling and optimization of white paint back reflectors for thin-film silicon solar cells

    NARCIS (Netherlands)

    Lipovšek, B.; Krč, J.; Isabella, O.; Zeman, M.; Topič, M.

    2010-01-01

    Diffusive dielectric materials such as white paint have been demonstrated as effective back reflectors in the photovoltaic technology. In this work, a one-dimensional (1D) optical modeling approach for simulation of white paint films is developed and implemented in a 1D optical simulator for thin-fi

  17. Numerical modelling of thin-walled hypereutectic ductile cast iron parts

    DEFF Research Database (Denmark)

    Pedersen, Karl Martin; Hattel, Jesper Henri; Tiedje, Niels Skat

    2006-01-01

    Solidification of hypereutectic thin-walled ductile cast iron has been modelled in one dimension taking into account the precipitation of off-eutectic austenite dendrites during solidification. The simulations have been compared with casting experiments on plate geometries with plate thicknesses...

  18. Metallurgical investigation of wire breakage of tyre bead grade

    Directory of Open Access Journals (Sweden)

    Piyas Palit

    2015-10-01

    Full Text Available Tyre bead grade wire is used for tyre making application. The wire is used as reinforcement inside the polymer of tyre. The wire is available in different size/section such as 1.6–0.80 mm thin Cu coated wire. During tyre making operation at tyre manufacturer company, wire failed frequently. In this present study, different broken/defective wire samples were collected from wire mill for detailed investigation of the defect. The natures of the defects were localized and similar in nature. The fracture surface was of finger nail type. Crow feet like defects including button like surface abnormalities were also observed on the broken wire samples. The defect was studied at different directions under microscope. Different advanced metallographic techniques have been used for detail investigation. The analysis revealed that, white layer of surface martensite was formed and it caused the final breakage of wire. In this present study we have also discussed about the possible reason for the formation of such kind of surface martensite (hard-phase.

  19. Fractal-based modeling of the stress-strain relation of Bi2Sr2CaCu2Ox/AgMg superconducting round wires

    Science.gov (United States)

    Gou, Xiaofan; Schwartz, Justin

    2013-10-01

    Bi2Sr2CaCu2Ox/AgMg (Bi2212) multi filamentary superconducting round wires (RWs) can be only potential candidate for constructing the superconducting magnet with higher magnetic field (>25T). Very complicated microstructure of Bi2212 RWs has been found by recent SEM studies, and then the vital problems of Characterization of this unique microstructure and further exploration of the correlation of macro electromechanical properties with this microstructure arise. In this paper, it is firstly found that the rough surface of individual filaments can be well characterized by fractals. On the geometrical model with the fractal simulation of the rough surface, stress-strain relation of Bi2212 RWs has been investigated. The modelling result with considering the rough surface has a better agreement to the experimental data. At the request of the authors, and with the agreement of the Proceedings Editor, the above paper in AIP Proceedings has been retracted (as of 26 November 2013) due to a prior publication by the authors which reports similar data/results. That paper was first published in volume 26 (issue 5) of the journal Superconductor Science and Technology and was published on 4 April 2013: Fractal analysis of the role of the rough interface between Bi2Sr2CaCu2Ox filaments and the Ag matrix in the mechanical behavior of composite round wires The authors wish to apologize for any inconvenience caused by publication of their AIP Proceedings article.

  20. Mathematical modelling of the thin layer solar drying of banana, mango and cassava

    Energy Technology Data Exchange (ETDEWEB)

    Koua, Kamenan Blaise; Fassinou, Wanignon Ferdinand; Toure, Siaka [Laboratoire d' Energie Solaire, Universite de Cocody- Abidjan, 22 BP 582 Abidjan 22 (Ivory Coast); Gbaha, Prosper [Laboratoire d' Energie Nouvelle et Renouvelable, Institut National Polytechnique, Felix HOUPHOUET - BOIGNY de Yamoussoukro (Ivory Coast)

    2009-10-15

    The main objectives of this paper are firstly to investigate the behaviour of the thin layer drying of plantain banana, mango and cassava experimentally in a direct solar dryer and secondly to perform mathematical modelling by using thin layer drying models encountered in literature. The variation of the moisture content of the products studied and principal drying parameters are analysed. Seven statistical models, which are empirical or semi-empirical, are tested to validate the experimental data. A non-linear regression analysis using a statistical computer program is used to evaluate the constants of the models. The Henderson and Pabis drying model is found to be the most suitable for describing the solar drying curves of plantain banana, mango and cassava. The drying data of these products have been analysed to obtain the values of the effective diffusivity during the falling drying rate phase. (author)

  1. Modeling a spheroidal microswimmer and cooperative swimming in thin films

    CERN Document Server

    Theers, Mario; Gompper, Gerhard; Winkler, Roland G

    2016-01-01

    We propose a hydrodynamic model for a spheroidal microswimmer with two tangential surface velocity modes. This model is analytically solvable and reduces to Lighthill's and Blake's spherical squirmer model in the limit of equal major and minor semi-axes. Furthermore, we present an implementation of such a spheroidal squirmer by means of multiparticle collision dynamics simulations. We investigate its properties as well as the scattering of two spheroidal squirmers in a slit geometry. Thereby we find a stable fixed point, where two pullers swim cooperatively forming a wedge-like conformation with a small constant angle.

  2. Asymptotic heat transfer model in thin liquid films

    CERN Document Server

    Chhay, Marx; Gisclon, Marguerite; Ruyer-Quil, Christian

    2015-01-01

    In this article, we present a modelling of heat transfer occuring through a liquid film flowing down a vertical wall. This model is formally derived thanks to asymptotic developpment, by considering the physical ratio of typical length scales of the study. A new Nusselt thermal solution is proposed, taking into account the hydrodynamic free surface variations and the contributions of the higher order terms in the asymptotic model are numerically pointed out. The comparisons are provided against the resolution of the full Fourier equations in a steady state frame.

  3. The effects of TV commercials using less thin models on young women's mood, body image and actual food intake

    NARCIS (Netherlands)

    Anschutz, D.J.; Engels, R.C.M.E.; Becker, E.S.; Strien, T. van

    2009-01-01

    This study experimentally tested the effects of exposure to television commercials using less thin models on mood, body focused anxiety and food intake, as compared to the effects of commercials using thin models. In a naturalistic setting, 110 young women were exposed to a neutral movie,

  4. Modelling of eddy-current interaction with cracks in the thin-skin regime. Two approaches

    Energy Technology Data Exchange (ETDEWEB)

    Mastorchio, S. [Electricite de France, 78 - Chatou (France). Research and Development Div.; Harfield, N. [Surrey Univ. (United Kingdom). Dept. of Physics

    1998-02-01

    EDF uses TRIFOU code for eddy current testing modelling. This general electromagnetic code is to be further adapted to Non Destructive Testing applications, not only for nuclear NDT but also in other fields such as aeronautical. This paper compares experimental data for aluminium and steel specimens with two methods of solving the forward problem in the thin-skin regime. The first approach is a 3D Finite Element / Boundary Integral Element method (TRIFOU) developed by EDF/RD Division (France). The second approach is specialized for the treatment of surface cracks in the thin-skin regime developed by the University of Surrey (England). In the thin-skin regime, the electromagnetic skin-depth is small compared with the depth of the crack. Such conditions are common in tests on steels and sometimes on aluminium. (K.A.) 4 refs.

  5. Quantum compact model for thin-body double-gate Schottky barrier MOSFETs

    Institute of Scientific and Technical Information of China (English)

    Luan Su-Zhen; Liu Hong-Xia

    2008-01-01

    Nanoscale Schottky barrier metal oxide semiconductor field-effect transistors (MOSFETs) are explored by using quantum mechanism effects for thin-body devices. The results suggest that for small nonnegative Schottky barrier heights, even for zero barrier height, the tunnelling current also plays a role in the total on-state current. Owing to the thin body of device, quantum confinement raises the electron energy levels in the silicon, and the tradeoff takes place between the quantum confinement energy and Schottky barrier lowering (SBL). It is concluded that the inclusion of the quantum mechanism effect in this model, which considers an infinite rectangular well with a first-order perturbation in the channel, can lead to the good agreement with numerical result for thin silicon film. The error increases with silicon thickness increasing.

  6. Self-healable electrically conducting wires for wearable microelectronics.

    Science.gov (United States)

    Sun, Hao; You, Xiao; Jiang, Yishu; Guan, Guozhen; Fang, Xin; Deng, Jue; Chen, Peining; Luo, Yongfeng; Peng, Huisheng

    2014-09-01

    Electrically conducting wires play a critical role in the advancement of modern electronics and in particular are an important key to the development of next-generation wearable microelectronics. However, the thin conducting wires can easily break during use, and the whole device fails to function as a result. Herein, a new family of high-performance conducting wires that can self-heal after breaking has been developed by wrapping sheets of aligned carbon nanotubes around polymer fibers. The aligned carbon nanotubes offer an effective strategy for the self-healing of the electric conductivity, whereas the polymer fiber recovers its mechanical strength. A self-healable wire-shaped supercapacitor fabricated from a wire electrode of this type maintained a high capacitance after breaking and self-healing.

  7. Heat Transfer Analysis in Wire Bundles for Aerospace Vehicles

    Science.gov (United States)

    Rickman, S. L.; Iamello, C. J.

    2016-01-01

    Design of wiring for aerospace vehicles relies on an understanding of "ampacity" which refers to the current carrying capacity of wires, either, individually or in wire bundles. Designers rely on standards to derate allowable current flow to prevent exceedance of wire temperature limits due to resistive heat dissipation within the wires or wire bundles. These standards often add considerable margin and are based on empirical data. Commercial providers are taking an aggressive approach to wire sizing which challenges the conventional wisdom of the established standards. Thermal modelling of wire bundles may offer significant mass reduction in a system if the technique can be generalized to produce reliable temperature predictions for arbitrary bundle configurations. Thermal analysis has been applied to the problem of wire bundles wherein any or all of the wires within the bundle may carry current. Wire bundles present analytical challenges because the heat transfer path from conductors internal to the bundle is tortuous, relying on internal radiation and thermal interface conductance to move the heat from within the bundle to the external jacket where it can be carried away by convective and radiative heat transfer. The problem is further complicated by the dependence of wire electrical resistivity on temperature. Reduced heat transfer out of the bundle leads to higher conductor temperatures and, hence, increased resistive heat dissipation. Development of a generalized wire bundle thermal model is presented and compared with test data. The steady state heat balance for a single wire is derived and extended to the bundle configuration. The generalized model includes the effects of temperature varying resistance, internal radiation and thermal interface conductance, external radiation and temperature varying convective relief from the free surface. The sensitivity of the response to uncertainties in key model parameters is explored using Monte Carlo analysis.

  8. Characteristics of coated copper wire specimens using high frequency ultrasonic complex vibration welding equipments.

    Science.gov (United States)

    Tsujino, J; Ihara, S; Harada, Y; Kasahara, K; Sakamaki, N

    2004-04-01

    Welding characteristic of thin coated copper wires were studied using 40, 60, 100 kHz ultrasonic complex vibration welding equipments with elliptical to circular vibration locus. The complex vibration systems consisted of a longitudinal-torsional vibration converter and a driving longitudinal vibration system. Polyurethane coated copper wires of 0.036 mm outer diameter and copper plates of 0.3 mm thickness and the other dimension wires were used as welding specimens. The copper wire part is completely welded on the copper substrate and the insulated coating material is driven from welded area to outsides of the wire specimens by high frequency complex vibration.

  9. Minimizing RF heating of conducting wires in MRI.

    Science.gov (United States)

    Yeung, Christopher J; Karmarkar, Parag; McVeigh, Elliot R

    2007-11-01

    Performing interventions using long conducting wires in MRI introduces the risk of focal RF heating at the wire tip. Comprehensive EM simulations are combined with carefully measured experimental data to show that method-of-moments EM field modeling coupled with heat transfer modeling can adequately predict RF heating with wires partially inserted into the patient-mimicking phantom. The effects of total wire length, inserted length, wire position in the phantom, phantom position in the scanner, and phantom size are examined. Increasing phantom size can shift a wire's length of maximum tip heating from about a half wave toward a quarter wave. In any event, with wires parallel to the scanner bore, wire tip heating is minimized by keeping the patient and wires as close as possible to the central axis of the scanner bore. At 1.5T, heating is minimized if bare wires are shorter than 0.6 m or between approximately 2.4 m and approximately 3.0 m. Heating is further minimized if wire insertion into phantoms equivalent to most aqueous soft tissues is less than 13 cm or greater than 40 cm (longer for fatty tissues, bone, and lung). The methods demonstrated can be used to estimate the absolute amount of heating in order to set RF power safety thresholds.

  10. MODELLING OF THIN LAYER DRYING KINETICS OF COCOA BEANS DURING ARTIFICIAL AND NATURAL DRYING

    Directory of Open Access Journals (Sweden)

    C.L. HII

    2008-04-01

    Full Text Available Drying experiments were conducted using air-ventilated oven and sun dryer to simulate the artificial and natural drying processes of cocoa beans. The drying data were fitted with several published thin layer drying models. A new model was introduced which is a combination of the Page and two-term drying model. Selection of the best model was investigated by comparing the determination of coefficient (R2, reduced chi-square (2 and root mean square error (RMSE between the experimental and predicted values. The results showed that the new model was found best described the artificial and natural drying kinetics of cocoa under the conditions tested.

  11. A Model of the Growth of Copper Selenide Thin Films Controlled by Diffusion and Chemical Reaction

    OpenAIRE

    Bottecchia,Otávio Luiz

    1998-01-01

    A model of the growth of thin films of copper selenides is proposed. A mathematical equation that describes the kinetics of the growth is derived. Simulated results and a discussion on the results of the model are presented. A fitting procedure of literature data with the derived equation is carried out. The diffusion coefficient of copper(I) ions in copper selenide is roughly estimated.

  12. TWO-LAYER MODEL DESCRIPTION OF POLYMER THIN FILM DYNAMICS

    Institute of Scientific and Technical Information of China (English)

    Dong-dong Peng; Ran-xing Nancy Li; Chi-hang Lam; Ophelia K.C.Tsui

    2013-01-01

    Experiments in the past two decades have shown that the glass transition temperature of polymer films can become noticeably different from that of the bulk when the film thickness is decreased below ca.100 nm.It is broadly believed that these observations are caused by a nanometer interfacial layer with dynamics faster or slower than that of the bulk.In this paper,we examine how this idea may be realized by using a two-layer model assuming a hydrodynamic coupling between the interfacial layer and the remaining,bulk-like layer in the film.Illustrative examples will be given showing how the two-layer model is applied to the viscosity measurements of polystyrene and polymethylmethacrylate films supported by silicon oxide,where divergent thickness dependences are observed.

  13. Optical Thin Film Modeling: Using FTG's FilmStar Software

    Science.gov (United States)

    Freese, Scott

    2009-01-01

    Every material has basic optical properties that define its interaction with light: The index of refraction (n) and extinction coefficient (k) vary for the material as a function of the wavelength of the incident light. Also significant are the phase velocity and polarization of the incident light These inherent properties allow for the accurate modeling of light s behavior upon contact with a surface: Reflectance, Transmittance, Absorptance.

  14. Investigating Lithosphere Strength With Thin-Shell Tectonic Modeling

    Science.gov (United States)

    Moder, C.; Carena, S.

    2007-12-01

    The behavior of many major faults on Earth can only be explained if they are assumed to be much weaker than expected from Byerlee's Law alone. However, there is no agreement over what is a realistic range of friction parameters for faults, or its possible dependency on fault network geometry. Both can be studied with numerical forward modeling, but this requires knowledge of the detailed 3-D geometry of the faults. The latter is now available for most of California, thanks to the SCEC Community Fault Model (southern California) and to the USGS program "3-D Geologic Maps and Visualization" (San Francisco Bay and surrounding region). We model the behavior of the California fault network with the finite-element code SHELLS. We use as input a coarse global grid, with local high-resolution representation of actual faults based on the existing 3-D fault maps. By comparing the simulation results with data on fault-slip rates, we can determine how the faults in this network interact, the role of small faults, and we can quantify the typical fault strength in a continental transform plate boundary setting.

  15. Design optimization of thin-film/wafer-based tandem junction solar cells using analytical modeling

    Science.gov (United States)

    Davidson, Lauren; Toor, Fatima

    2016-03-01

    Several research groups are developing solar cells of varying designs and materials that are high efficiency as well as cost competitive with the single junction silicon (Si) solar cells commercially produced today. One of these solar cell designs is a tandem junction solar cell comprised of perovskite (CH3NH3PbI3) and silicon (Si). Loper et al.1 was able to create a 13.4% efficient tandem cell using a perovskite top cell and a Si bottom cell, and researchers are confident that the perovskite/Si tandem cell can be optimized in order to reach higher efficiencies without introducing expensive manufacturing processes. However, there are currently no commercially available software capable of modeling a tandem cell that is based on a thin-film based bottom cell and a wafer-based top cell. While PC1D2 and SCAPS3 are able to model tandem cells comprised solely of thin-film absorbers or solely of wafer-based absorbers, they result in convergence errors if a thin-film/wafer-based tandem cell, such as the perovskite/ Si cell, is modeled. The Matlab-based analytical model presented in this work is capable of modeling a thin-film/wafer-based tandem solar cell. The model allows a user to adjust the top and bottom cell parameters, such as reflectivity, material bandgaps, donor and acceptor densities, and material thicknesses, in order to optimize the short circuit current, open circuit voltage, and quantum efficiency of the tandem solar cell. Using the Matlab-based analytical model, we were able optimize a perovskite/Si tandem cell with an efficiency greater than 30%.

  16. Surface superconductivity in thin cylindrical Bi nanowire.

    Science.gov (United States)

    Tian, Mingliang; Wang, Jian; Ning, Wei; Mallouk, Thomas E; Chan, Moses H W

    2015-03-11

    The physical origin and the nature of superconductivity in nanostructured Bi remains puzzling. Here, we report transport measurements of individual cylindrical single-crystal Bi nanowires, 20 and 32 nm in diameter. In contrast to nonsuperconducting Bi nanoribbons with two flat surfaces, cylindrical Bi nanowires show superconductivity below 1.3 K. However, their superconducting critical magnetic fields decrease with their diameter, which is the opposite of the expected behavior for thin superconducting wires. Quasiperiodic oscillations of magnetoresistance were observed in perpendicular fields but were not seen in the parallel orientation. These results can be understood by a model of surface superconductivity with an enhanced surface-to-bulk volume in small diameter wires, where the superconductivity originates from the strained surface states of the nanowires due to the surface curvature-induced stress.

  17. Carbon nanotube thin film strain sensor models assembled using nano- and micro-scale imaging

    Science.gov (United States)

    Lee, Bo Mi; Loh, Kenneth J.; Yang, Yuan-Sen

    2017-02-01

    Nanomaterial-based thin films, particularly those based on carbon nanotubes (CNT), have brought forth tremendous opportunities for designing next-generation strain sensors. However, their strain sensing properties can vary depending on fabrication method, post-processing treatment, and types of CNTs and polymers employed. The objective of this study was to derive a CNT-based thin film strain sensor model using inputs from nano-/micro-scale experimental measurements of nanotube physical properties. This study began with fabricating ultra-low-concentration CNT-polymer thin films, followed by imaging them using atomic force microscopy. Image processing was employed for characterizing CNT dispersed shapes, lengths, and other physical attributes, and results were used for building five different types of thin film percolation-based models. Numerical simulations were conducted to assess how the morphology of dispersed CNTs in its 2D matrix affected bulk film electrical and electromechanical (strain sensing) properties. The simulation results showed that CNT morphology had a significant impact on strain sensing performance.

  18. Carbon nanotube thin film strain sensor models assembled using nano- and micro-scale imaging

    Science.gov (United States)

    Lee, Bo Mi; Loh, Kenneth J.; Yang, Yuan-Sen

    2017-07-01

    Nanomaterial-based thin films, particularly those based on carbon nanotubes (CNT), have brought forth tremendous opportunities for designing next-generation strain sensors. However, their strain sensing properties can vary depending on fabrication method, post-processing treatment, and types of CNTs and polymers employed. The objective of this study was to derive a CNT-based thin film strain sensor model using inputs from nano-/micro-scale experimental measurements of nanotube physical properties. This study began with fabricating ultra-low-concentration CNT-polymer thin films, followed by imaging them using atomic force microscopy. Image processing was employed for characterizing CNT dispersed shapes, lengths, and other physical attributes, and results were used for building five different types of thin film percolation-based models. Numerical simulations were conducted to assess how the morphology of dispersed CNTs in its 2D matrix affected bulk film electrical and electromechanical (strain sensing) properties. The simulation results showed that CNT morphology had a significant impact on strain sensing performance.

  19. Coating of a steel wire with copper

    Science.gov (United States)

    Vdovin, K. N.; Dubskii, G. A.; Nefed'ev, A. A.; Derevyanko, D. V.

    2016-03-01

    The process of coating of a steel wire with liquid copper at a high speed (>1 m/s) is considered. The results of long-term studies of copperizing under laboratory conditions and electron-microscopic investigation of the copper-steel adhesion are used to develop a mathematical model for coating of a steel wire with copper and to create a commercial setup to implement this process.

  20. Considerations for modeling thin cirrus effects via brightness temperature differences

    Science.gov (United States)

    Schmidt, E. O.; Arduini, R. F.; Wielicki, B. A.; Stone, R. S.; Tsay, S.-C.

    1995-01-01

    Brightness temperature difference (BTD) values are calculated for selected Geostationary Operational Environmental Satellite (GOES-6) channels (3.9, 12.7 micrometer) and Advanced Very High Resolution Radiometer channels (3.7, 12.0 micrometer). Daytime and nighttime discrimination of particle size information is possible given the infrared cloud extinction optical depth and the BTD value. BTD values are presented and compared for cirrus clouds composed of equivalent ice spheres (volume, surface area) versus randomly oriented hexagonal ice crystals. The effect of the hexagonal ice crystals is to increase the magnitude of the BTD values calculated relative to equivalent ice sphere (volume, surface area) BTDs. Equivalent spheres (volume or surface area) do not do a very good job of modeling hexagonal ice crystal effects on BTDs; however, the use of composite spheres improves the simulation and offers interesting prospects. Careful consideration of the number of Legendre polynomial coefficients used to fit the scattering phase functions is crucial to realistic modeling of cirrus BTDs. Surface and view-angle effects are incorporated to provide more realistic simulation.

  1. Qualitative Behaviour of Solutions in Two Models of Thin Liquid Films

    Directory of Open Access Journals (Sweden)

    Matthew Michal

    2016-01-01

    Full Text Available For the thin-film model of a viscous flow which originates from lubrication approximation and has a full nonlinear curvature term, we prove existence of nonnegative weak solutions. Depending on initial data, we show algebraic or exponential dissipation of an energy functional which implies dissipation of the solution arc length that is a well known property for a Hele-Shaw flow. For the classical thin-film model with linearized curvature term, under some restrictions on parameter and gradient values, we also prove analytically the arc length dissipation property for positive solutions. We compare the numerical solutions for both models, with nonlinear and with linearized curvature terms. In regimes when solutions develop finite time singularities, we explain the difference in qualitative behaviour of solutions.

  2. A coarse-grained model to study calcium activation of the cardiac thin filament

    Science.gov (United States)

    Zhang, Jing; Schwartz, Steven

    2015-03-01

    Familial hypertrophic cardiomyopathy (FHC) is one of the most common heart disease caused by genetic mutations. Cardiac muscle contraction and relaxation involve regulation of crossbridge binding to the cardiac thin filament, which regulates actomyosin interactions through calcium-dependent alterations in the dynamics of cardiac troponin (cTn) and tropomyosin (Tm). An atomistic model of cTn complex interacting with Tm has been studied by our group. A more realistic model requires the inclusion of the dynamics of actin filament, which is almost 6 times larger than cTn and Tm in terms of atom numbers, and extensive sampling of the model becomes very resource-demanding. By using physics-based protein united-residue force field, we introduce a coarse-grained model to study the calcium activation of the thin filament resulting from cTn's allosteric regulation of Tm dynamics on actin. The time scale is much longer than that of all-atom molecular dynamics simulation because of the reduction of the degrees of freedom. The coarse-grained model is a good template for studying cardiac thin filament mutations that cause FHC, and reduces the cost of computational resources.

  3. The essential oil components of Cinnamomum cassia:an analysis under different thinning models of plantation Pinus massoniana

    Institute of Scientific and Technical Information of China (English)

    Dayan Tao; Yuanfa Li; Daodiao Lu; Yehong Luo; Sufang Yu; Shaoming Ye

    2016-01-01

    Thinning is an important activity employed in forest management. To date, studies have mainly focused on the effects of thinning on the growth of trees during the same thinning period. In this study, plantation Pinus mas-soniana Lamb. near maturity were thinned at varying intensities and an economically important species, Cin-namomum cassia Presl., was planted beneath the thinned canopy. The aim of the study was to explore the effects of the extent of thinning on the essential oil content and its components of C. cassia in different parts of the plant, as well as the economic feasibility of the P. massoniana–C. cassia management model. Thinning significantly reduced the oil yield in the bark and branches of C. cassia, but hardly impacted the oil yield from C. cassia leaves com-pared with pure C. cassia forest (CK). Among the different thinning treatments, both light (T.4) and extensive (T.1) thinning reduced the oil yield of C. cassia bark and new branches. The concentrations of the main aldehydes differed in different parts of the plant and were affected by the extent of thinning. The influence on cinnamaldehyde in the bark was minor, but was much greater in the branches and leaves. Both the oil yield and content of cinnamalde-hyde showed that moderate (T.3) thinning was more favorable than other thinning models. These results not only provide a potentially promising model for the trans-formation of low–yield artificial pure forests of P. masso-niana in the future, but also offer a reference for the management of artificial mixed stands.

  4. Comparison between two models of absorption of matter waves by a thin time-dependent barrier

    Science.gov (United States)

    Barbier, Maximilien; Beau, Mathieu; Goussev, Arseni

    2015-11-01

    We report a quantitative, analytical, and numerical comparison between two models of the interaction of a nonrelativistic quantum particle with a thin time-dependent absorbing barrier. The first model represents the barrier by a set of time-dependent discontinuous matching conditions, which are closely related to Kottler boundary conditions used in stationary-wave optics as a mathematical basis for Kirchhoff diffraction theory. The second model mimics the absorbing barrier with an off-diagonal δ potential with a time-dependent amplitude. We show that the two models of absorption agree in their predictions in a semiclassical regime, the regime readily accessible in modern experiments with ultracold atoms.

  5. Comparison of the copper and gold wire bonding processes for LED packaging*

    Institute of Scientific and Technical Information of China (English)

    Chen Zhaohui; Liu Yong; Liu Sheng

    2011-01-01

    Wire bonding is one of the main processes of the LED packaging which provides electrical interconnection between the LED chip and lead frame The gold wire bonding process has been widely used in LED packaging industry currently. However, due to the high cost of gold wire, copper wire bonding is a good substitute for the gold wire bonding which can lead to significant cost saving. In this paper, the copper and gold wire bonding processes on the high power LED chip are compared and analyzed with finite element simulation. This modeling work may provide guidelines for the parameter optimization of coppor wire bonding process on the high power LED packaging.

  6. Phase Field Models for Thin Elastic Structures with Topological Constraint

    Science.gov (United States)

    Dondl, Patrick W.; Lemenant, Antoine; Wojtowytsch, Stephan

    2017-02-01

    This article is concerned with the problem of minimising the Willmore energy in the class of connected surfaces with prescribed area which are confined to a small container. We propose a phase field approximation based on De Giorgi's diffuse Willmore functional to this variational problem. Our main contribution is a penalisation term which ensures connectedness in the sharp interface limit. The penalisation of disconnectedness is based on a geodesic distance chosen to be small between two points that lie on the same connected component of the transition layer of the phase field. We prove that in two dimensions, sequences of phase fields with uniformly bounded diffuse Willmore energy and diffuse area converge uniformly to the zeros of a double-well potential away from the support of a limiting measure. In three dimensions, we show that they converge H^1-almost everywhere on curves. This enables us to show {Γ}-convergence to a sharp interface problem that only allows for connected structures. The results also imply Hausdorff convergence of the level sets in two dimensions and a similar result in three dimensions. Furthermore, we present numerical evidence of the effectiveness of our model. The implementation relies on a coupling of Dijkstra's algorithm in order to compute the topological penalty to a finite element approach for the Willmore term.

  7. Notched K-wire for low thermal damage bone drilling.

    Science.gov (United States)

    Liu, Yao; Belmont, Barry; Wang, Yiwen; Tai, Bruce; Holmes, James; Shih, Albert

    2017-07-01

    The Kirschner wire (K-wire) is a common bone drilling tool in orthopedic surgery to affix fractured bone. Significant heat is produced due to both the cutting and the friction between the K-wire and the bone debris during drilling. Such heat can result in high temperatures, leading to osteonecrosis and other secondary injuries. To reduce thermal injury and other high-temperature associated complications, a new K-wire design with three notches along the three-plane trocar tip fabricated using a thin micro-saw tool is studied. These notches evacuate bone debris and reduce the clogging and heat generation during bone drilling. A set of four K-wires, one without notches and three notched, with depths of 0.5, 0.75, and 1mm, are evaluated. Bone drilling experiments conducted on bovine cortical bone show that notched K-wires could effectively decrease the temperature, thrust force, and torque during bone drilling. K-wires with notches 1mm deep reduced the thrust force and torque by approximately 30%, reduced peak temperatures by 43%, and eliminated blackened burn marks in bone. This study demonstrates that a simple modification of the tip of K-wires can effectively reduce bone temperatures during drilling. Copyright © 2017 IPEM. Published by Elsevier Ltd. All rights reserved.

  8. The model thin film alumina catalyst support suitable for catalysis-oriented surface science studies

    Energy Technology Data Exchange (ETDEWEB)

    Nartova, Anna V., E-mail: avnartova@gmail.com [Boreskov Institute of Catalysis SB RAS, Lavrentieva Ave., 5, Novosibirsk, 630090 (Russian Federation); Novosibirsk State University, Pirogova St., 2, Novosibirsk, 630090 (Russian Federation); Bukhtiyarov, Andrey V., E-mail: avb@catalysis.ru [Boreskov Institute of Catalysis SB RAS, Lavrentieva Ave., 5, Novosibirsk, 630090 (Russian Federation); Kvon, Ren I., E-mail: kvon@catalysis.ru [Boreskov Institute of Catalysis SB RAS, Lavrentieva Ave., 5, Novosibirsk, 630090 (Russian Federation); Bukhtiyarov, Valerii I., E-mail: vib@catalysis.ru [Boreskov Institute of Catalysis SB RAS, Lavrentieva Ave., 5, Novosibirsk, 630090 (Russian Federation); Novosibirsk State University, Pirogova St., 2, Novosibirsk, 630090 (Russian Federation)

    2015-09-15

    Graphical abstract: - Highlights: • New model catalyst on “AlOx-thin film/FeCrAl” support is presented. • Metal substrate minimizes sample charging, allows fast and uniform heating. • Surface is rough to model the catalyst support's morphology. • Planar alumina is stable in air/gases/solutions and similar to γ-Al{sub 2}O{sub 3}. • New model support is suitable for in situ XPS, STM, TPD, TPR, etc. - Abstract: The preparation of thin continuous alumina film at the surface of metal substrate in UHV (ultra high vacuum) conditions is described. The peculiarities of the obtained films studied by XPS (X-ray photoelectron spectroscopy) and STM (scanning tunneling microscopy) are discussed. The long-term durability of the oxide film was tested and proved both under ambient conditions and in acidic aqueous solutions. The stability of the planar alumina samples toward oxidation by oxygen was checked in the wide ranges of gas pressure and sample temperature. The suggested procedure ensures the controlled and reproducible preparation of thin alumina films – model support appropriate for wet chemistry catalyst preparation, suitable for STM and for other Surface Science techniques studies of alumina supported metal catalysts.

  9. Scattering of Electromagnetic Waves by Many Nano-Wires

    Directory of Open Access Journals (Sweden)

    Alexander G. Ramm

    2013-07-01

    Full Text Available Electromagnetic wave scattering by many parallel to the z−axis, thin, impedance, parallel, infinite cylinders is studied asymptotically as a → 0. Let Dm be the cross-section of the m−th cylinder, a be its radius and xˆm = (xm1, xm2 be its center, 1 ≤ m ≤ M , M =   M (a. It is assumed that the points, xˆm, are distributed, so that N (∆  = (1 / 2πa * ∫∆ N (xˆdxˆ[1 + o(1], where N (∆ is the number of points, xˆm, in an arbitrary open subset, ∆, of the plane, xoy. The function, N (xˆ ≥ 0, is a continuous function, which an experimentalist can choose. An equation for the self-consistent (effective field is derived as a → 0. A formula is derived for the refraction coefficient in the medium in which many thin impedance cylinders are distributed. These cylinders may model nano-wires embedded in the medium. One can produce a desired refraction coefficient of the new medium by choosing a suitable boundary impedance of the thin cylinders and their distribution law.

  10. Modeling of cardiac muscle thin films: pre-stretch, passive and active behavior.

    Science.gov (United States)

    Shim, Jongmin; Grosberg, Anna; Nawroth, Janna C; Parker, Kevin Kit; Bertoldi, Katia

    2012-03-15

    Recent progress in tissue engineering has made it possible to build contractile bio-hybrid materials that undergo conformational changes by growing a layer of cardiac muscle on elastic polymeric membranes. Further development of such muscular thin films for building actuators and powering devices requires exploring several design parameters, which include the alignment of the cardiac myocytes and the thickness/Young's modulus of elastomeric film. To more efficiently explore these design parameters, we propose a 3-D phenomenological constitutive model, which accounts for both the passive deformation including pre-stretch and the active behavior of the cardiomyocytes. The proposed 3-D constitutive model is implemented within a finite element framework, and can be used to improve the current design of bio-hybrid thin films and help developing bio-hybrid constructs capable of complex conformational changes. Copyright © 2011 Elsevier Ltd. All rights reserved.

  11. Heat and mass transfer in nanofluid thin film over an unsteady stretching sheet using Buongiorno's model

    Science.gov (United States)

    Qasim, M.; Khan, Z. H.; Lopez, R. J.; Khan, W. A.

    2016-01-01

    The heat and mass transport of a nanofluid thin film over an unsteady stretching sheet has been investigated. This is the first paper on nanofluid thin film flow caused by unsteady stretching sheet using Buongiorno's model. The model used for the nanofluid film incorporates the effects of Brownian motion and thermophoresis. The self-similar non-linear ordinary differential equations are solved using Maple's built-in BVP solver. The results for pure fluid are found to be in good agreement with the literature. Present analysis shows that free surface temperature and nanoparticle volume fraction increase with both unsteadiness and magnetic parameters. The results reveal that effect of both nanofluid parameters and viscous dissipation is to reduce the heat transfer rate.

  12. Mixed finite element models for free vibrations of thin-walled beams

    Science.gov (United States)

    Noor, Ahmed K.; Peters, Jeanne M.; Min, Byung-Jin

    1989-01-01

    Simple, mixed finite element models are developed for the free vibration analysis of curved thin-walled beams with arbitrary open cross section. The analytical formulation is based on a Vlasov's type thin-walled beam theory with the effects of flexural-torsional coupling, transverse shear deformation and rotary inertia included. The fundamental unknowns consist of seven internal forces and seven generalized displacements of the beam. The element characteristic arrays are obtained by using a perturbed Lagrangian-mixed variational principle. Only C(sup o) continuity is required for the generalized displacements. The internal forces and the Lagrange multiplier are allowed to be discontinuous at interelement boundaries. Numerical results are presented to demonstrate the high accuracy and effectiveness of the elements developed. The standard of comparison is taken to be the solutions obtained by using 2-D plate/shell models for the beams.

  13. Numerical modelling of solidification of thin walled hypereutectic ductile cast iron

    DEFF Research Database (Denmark)

    Pedersen, Karl Martin; Hattel, Jesper; Tiedje, Niels

    2006-01-01

    Numerical simulation of solidification of ductile cast iron is normally based on a model where graphite nodules are surrounded by an austenite shell. The two phases are then growing as two concentric spheres governed by diffusion of carbon through the austenite shell. Experiments have however shown...... simulation of thin-walled ductile iron castings. Simulations have been performed with a 1-D numerical solidi¬fication model that includes the precipitation of non-eutectic austenite during the eutectic stage. Results from the simulations have been compared with experimental castings with wall thick...... the presence of austenite dendrites even in hypereutectic castings. In thin-walled castings the presence of austenite dendrites is even more pronounced, which increases the risk of shrinkage porosities. This off-eutectic austenite is therefore an important part that should be taken into account during...

  14. Copper wire bonding

    CERN Document Server

    Chauhan, Preeti S; Zhong, ZhaoWei; Pecht, Michael G

    2014-01-01

    This critical volume provides an in-depth presentation of copper wire bonding technologies, processes and equipment, along with the economic benefits and risks.  Due to the increasing cost of materials used to make electronic components, the electronics industry has been rapidly moving from high cost gold to significantly lower cost copper as a wire bonding material.  However, copper wire bonding has several process and reliability concerns due to its material properties.  Copper Wire Bonding book lays out the challenges involved in replacing gold with copper as a wire bond material, and includes the bonding process changes—bond force, electric flame off, current and ultrasonic energy optimization, and bonding tools and equipment changes for first and second bond formation.  In addition, the bond–pad metallurgies and the use of bare and palladium-coated copper wires on aluminum are presented, and gold, nickel and palladium surface finishes are discussed.  The book also discusses best practices and re...

  15. In vitro and in vivo evaluation of a shape memory polymer foam-over-wire embolization device delivered in saccular aneurysm models.

    Science.gov (United States)

    Boyle, Anthony J; Landsman, Todd L; Wierzbicki, Mark A; Nash, Landon D; Hwang, Wonjun; Miller, Matthew W; Tuzun, Egemen; Hasan, Sayyeda M; Maitland, Duncan J

    2016-10-01

    Current endovascular therapies for intracranial saccular aneurysms result in high recurrence rates due to poor tissue healing, coil compaction, and aneurysm growth. We propose treatment of saccular aneurysms using shape memory polymer (SMP) foam to improve clinical outcomes. SMP foam-over-wire (FOW) embolization devices were delivered to in vitro and in vivo porcine saccular aneurysm models to evaluate device efficacy, aneurysm occlusion, and acute clotting. FOW devices demonstrated effective delivery and stable implantation in vitro. In vivo porcine aneurysms were successfully occluded using FOW devices with theoretical volume occlusion values greater than 72% and rapid, stable thrombus formation. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1407-1415, 2016.

  16. Chemistry of radiation damage to wire chambers

    Energy Technology Data Exchange (ETDEWEB)

    Wise, J.

    1992-08-01

    Proportional counters are used to study aspects of radiation damage to wire chambers (wire aging). Principles of low-pressure, rf plasma chemistry are used to predict the plasma chemistry in electron avalanches (1 atm, dc). (1) Aging is studied in CF{sub 4}/iC{sub 4}H{sub 10} gas mixtures. Wire deposits are analyzed by Auger electron spectroscopy. An apparent cathode aging process resulting in loss of gain rather than in a self-sustained current is observed in CF{sub 4}-rich gases. A four-part model considering plasma polymerization of the hydrocarbon, etching of wire deposits by CF{sub 4}, acceleration of deposition processes in strongly etching environments, and reactivity of the wire surface is developed to understand anode wire aging in CF{sub 4}/iC{sub 4}H{sub 10} gases. Practical guidelines suggested by the model are discussed. (2) Data are presented to suggest that trace amounts of Freons do not affect aging rates in either dimethyl ether or Ar/C{sub 2}H{sub 6}. Apparent loss of gain is explained by attachment of primary electrons to a continuously increasing concentration of Freon 11 (CCl{sub 3}F) in the counter gas. An increase in the concentration of Freon 11 in dimethyl ether is caused by a distillation process in the gas supply bottle and is a natural consequence of the unequal volatilities of the two compounds.

  17. A constrained theory for single crystal shape memory wires with application to restrained recovery

    Science.gov (United States)

    Rizzoni, Raffaella

    2011-07-01

    The theory of thin wires developed in Dret and Meunier (Comptes Rendus de l'Académie des Sciences. Série I. Mathématique 337:143-147, 2003) is adapted to phase-transforming materials with large elastic moduli in the sense discussed in James and Rizzoni (J Elast 59:399-436, 2000). The result is a one-dimensional constitutive model for shape memory wires, characterized by a small number of material constants. The model is used to analyze self-accommodated and detwinned microstructures and to study superelasticity. It also turns out that the model successfully reproduces the behavior of shape memory wires in experiments of restrained recovery (Tsoi et al. in Mater Sci Eng A 368:299-310, 2004; Tsoi in 50:3535-3544, 2002; S̆ittner et al. in Mater Sci Eng A 286:298-311, 2000; vokoun in Smart Mater Struct 12:680-685, 2003; Zheng and Cui in Intermetallics 12:1305-1309, 2004; Zheng et al. in J Mater Sci Technol 20(4):390-394, 2004). In particular, the model is able to predict the shift to higher transformation temperatures on heating. The model also captures the effect of prestraining on the evolution of the recovery stress and of the martensite volume fraction.

  18. Development of Mathematical Models for Detecting Micron Scale Volumetric Defects in Thin Film Coatings

    Directory of Open Access Journals (Sweden)

    Gaigals G.

    2016-04-01

    Full Text Available The focus of the present research is to investigate possibilities of volumetric defect detection in thin film coatings on glass substrates by means of high definition imaging with no complex optical systems, such as lenses, and to determine development and construction feasibility of a defectoscope employing the investigated methods. Numerical simulations were used to test the proposed methods. Three theoretical models providing various degrees of accuracy and feasibility were studied.

  19. Weak solutions to a thin film model with capillary effects and insoluble surfactant

    CERN Document Server

    Escher, Joachim; Laurencot, Philippe; Walker, Christoph

    2011-01-01

    The paper focuses on a model describing the spreading of an insoluble surfactant on a thin viscous film with capillary effects taken into account. The governing equation for the film height is degenerate parabolic of fourth order and coupled to a second order parabolic equation for the surfactant concentration. It is shown that nonnegative weak solutions exist under natural assumptions on the surface tension coefficient.

  20. A physical surface-potential-based drain current model for polysilicon thin-film transistors

    Institute of Scientific and Technical Information of China (English)

    Li Xiyue; Deng Wanling; Huang Junkai

    2012-01-01

    A physical drain current model of polysilicon thin-film transistors based on the charge-sheet model,the density of trap states and surface potential is proposed.The model uses non-iterative calculations,which are single-piece and valid in all operation regions above flat-band voltage.The distribution of the trap states,including both Gaussian deep-level states and exponential band-tail states,is also taken into account,and parameter extraction of trap state distribution is developed by the optoelectronic modulation spectroscopy measurement method.Comparisons with the available experimental data are accomplished,and good agreements are obtained.

  1. Impact dynamics model of long span high voltage transmission lines subjected to iced wire breakage%大跨越高压输电线路覆冰断线的冲击动力学模型

    Institute of Scientific and Technical Information of China (English)

    刘春城; 初佂宇; 孙显鹤; 张伟

    2012-01-01

    In order to theoretically reveal the impact dynamic responses of long span high voltage transmission lines subjected to iced wire breakage, the impact dynamics model for long span high-voltage transmission lines with iced bundled conductors was developed comprehensively by using an equivalent single iced conductor instead of bundled conductors. The impact dynamics model of iced wire breakage was derived by using energy method. Taking a typical tension section of long span high-voltage transmission line as an example, the impact responses under iced wire breakage and non-iced wire breakage were computed by using this model and a good agreements were achieved. The results show that the impact dynamic response under iced wire breakage is larger than that under non-iced wire breakage, so the impact dynamic response due to iced wire breakage should not be ignored. The model can provide a theoretical basis for experiments and numerical simulations of long span high voltage transmission lines under iced wire breakage.%为了从理论上揭示大跨越高压输电线路覆冰断线的冲击动力响应,针对大跨越高压输电导线分裂布置型式的线路覆冰情况,采用等效单根导线代替分裂导线,利用能量法,建立了覆冰断线的冲击动力学模型.以某大跨越高压输电线路的一个典型耐张段为例,应用该模型计算导(地)线覆冰断线和未覆冰断线工况下对铁塔造成的冲击响应.研究表明:覆冰断线造成的冲击动力响应远大于未覆冰断线情况,覆冰断线冲击响应不容忽视.该模型可为大跨越高压输电线路覆冰断线的冲击动力响应试验分析与数值计算提供理论依据.

  2. Illumination System Modeling Techniques in Wire Bonding Pattern Recognition System%引线键合图形识别系统中的照明系统模拟技术

    Institute of Scientific and Technical Information of China (English)

    Wayne Yong; Cai Xiao Jin; Hong Meng Ho

    2006-01-01

    A method has been proposed to model the illumination characteristics of a typical wire bonder vision system. The proposed model can be used to calibrate the illumination of the vision system to ensure the same level of illumination brightness across different machines, given the same lighting level setting. The approach to extract the machine illumination model is semi-empirical and the model provides a closed-form solution.

  3. Magnetotail Current Sheet Thinning and Magnetic Reconnection Dynamics in Global Modeling of Substorms

    Science.gov (United States)

    Kuznetsova, M. M.; Hesse, M.; Rastaetter, L.; Toth, G.; DeZeeuw, D. L.; Gombosi, T. I.

    2008-01-01

    Magnetotail current sheet thinning and magnetic reconnection are key elements of magnetospheric substorms. We utilized the global MHD model BATS-R-US with Adaptive Mesh Refinement developed at the University of Michigan to investigate the formation and dynamic evolution of the magnetotail thin current sheet. The BATSRUS adaptive grid structure allows resolving magnetotail regions with increased current density up to ion kinetic scales. We investigated dynamics of magnetotail current sheet thinning in response to southwards IMF turning. Gradual slow current sheet thinning during the early growth phase become exponentially fast during the last few minutes prior to nightside reconnection onset. The later stage of current sheet thinning is accompanied by earthward flows and rapid suppression of normal magnetic field component $B-z$. Current sheet thinning set the stage for near-earth magnetic reconnection. In collisionless magnetospheric plasma, the primary mechanism controlling the dissipation in the vicinity of the reconnection site is non-gyrotropic effects with spatial scales comparable with the particle Larmor radius. One of the major challenges in global MHD modeling of the magnetotail magnetic reconnection is to reproduce fast reconnection rates typically observed in smallscale kinetic simulations. Bursts of fast reconnection cause fast magnetic field reconfiguration typical for magnetospheric substorms. To incorporate nongyritropic effects in diffusion regions we developed an algorithm to search for magnetotail reconnection sites, specifically where the magnetic field components perpendicular to the local current direction approaches zero and form an X-type configuration. Spatial scales of the diffusion region and magnitude of the reconnection electric field are calculated self-consistently using MHD plasma and field parameters in the vicinity of the reconnection site. The location of the reconnection sites and spatial scales of the diffusion region are updated

  4. Electronic transport in Si:P δ-doped wires

    DEFF Research Database (Denmark)

    Smith, J. S.; Drumm, D. W.; Budi, Akin

    2015-01-01

    Despite the importance of Si:P δ-doped wires for modern nanoelectronics, there are currently no computational models of electron transport in these devices. In this paper we present a nonequilibrium Green’s function model for electronic transport in a δ-doped wire, which is described by a tight...... for a variety of δ-doped wires, each with different donor configurations. These calculations also allow us to accurately define the electronic extent of a δ-doped wire, which we find to be at least 4.6 nm....

  5. Thin layer modeling of tom yum herbs in vacuum heat pump dryer.

    Science.gov (United States)

    Artnaseaw, A; Theerakulpisut, S; Benjapiyaporn, C

    2010-04-01

    Thin layer vacuum heat pump drying experiments were conducted to determine drying models for Tom Yum herbs (chili, lemon grass, kaffir lime leaf and galangal slice). The drying experiments were conducted in a vacuum heat pump dryer at a constant drying pressure of 0.2 bars and drying temperatures ranging from 50 °C to 65 °C. The experimental results were fitted to a number of well-known thin layer drying models and it was found, for the range of drying temperature tested, that the Midilli model is the best model for all Tom Yum herbs. To account for the influence of drying temperature, the constants and coefficients of model were formulated as functions of the drying temperature. Statistical tests of agreement between the model and experimental results were performed by determining the coefficient of determination (R²) , reduced chi-square (χ²) and root mean square error (RMSE). It was found that the model is in very good agreement with the experimental results.

  6. Depositing High-T(sub c) Superconductors On Normal-Conductor Wires

    Science.gov (United States)

    Kirlin, Peter S.

    1994-01-01

    Experiments have demonstrated feasibility of depositing thin layers of high-T(sub c) superconductor on normally electrically conductive wires. Superconductivity evident at and below critical temperature (T{sub c}) of 71 K. OMCVD, organometallic vapor deposition, apparatus coats Ag wire with layer high-T(sub c) superconductor. Superconductive phase of this material formed subsequently by annealing under controlled conditions.

  7. Effect of iodine on the corrosion of Au-Al wire bonds

    DEFF Research Database (Denmark)

    Verdingovas, Vadimas; Müller, Lutz; Jellesen, Morten Stendahl

    2015-01-01

    Corrosion study was performed on Au-Al wire bonds, thin layers of sputter deposited Au and Al, and Au-Al intermetallic nuggets. The test environment was iodine-vapour in air (1. mg/L) at 85 °C with varying relative humidity, and 500 mg/L of KI in water. GDOES, XRD, SEM EDS, wire bond shear...

  8. Efficient wire-grid duplexer-polarized for CO2 lasers

    Science.gov (United States)

    Cheo, P. K.; Bass, C. D.

    1972-01-01

    Chromium wire grid duplexer-polarizer for 10 micrometer carbon dioxide laser communication system is produced by depositing photo-resist film onto silicon substrate, grating by two collimated cadmium helium laser beams, covering of surface with thin chromium layer, and subsequent stripping of uncoated portion to expose etched wires.

  9. Subchannel Analysis of Wire Wrapped SCWR Assembly

    Directory of Open Access Journals (Sweden)

    Jianqiang Shan

    2014-01-01

    Full Text Available Application of wire wrap spacers in SCWR can reduce pressure drop and obtain better mixing capability. As a consequence, the required coolant pumping power is decreased and the coolant temperature profile inside the fuel bundle is flattened which will obviously decrease the peak cladding temperature. The distributed resistance model for wire wrap was developed and implemented in ATHAS subchannel analysis code. The HPLWR wire wrapped assembly was analyzed. The results show that: (1 the assembly with wire wrap can obtain a more uniform coolant temperature profile than the grid spaced assembly, which will result in a lower peak cladding temperature; (2 the pressure drop in a wire wrapped assembly is less than that in a grid spaced assembly, which can reduce the operating power of pump effectively; (3 the wire wrap pitch has significant effect on the flow in the assembly. Smaller Hwire/Drod will result in stronger cross flow a more uniform coolant temperature profile, and also a higher pressure drop.

  10. Mathematical modeling of thin-layer drying of fermented and non-fermented sugarcane bagasse

    Energy Technology Data Exchange (ETDEWEB)

    Mazutti, Marcio A.; Zabot, Giovani; Boni, Gabriela; Skovronski, Aline; de Oliveira, Debora; Di Luccio, Marco; Oliveira, J. Vladimir; Treichel, Helen [Department of Food Engineering, URI - Campus de Erechim, P.O. Box 743, CEP 99700-000, Erechim - RS (Brazil); Rodrigues, Maria Isabel; Maugeri, Francisco [Department of Food Engineering, Faculty of Food Engineering, University of Campinas - UNICAMP, P.O. Box 6121, CEP 13083-862, Campinas - SP (Brazil)

    2010-05-15

    This work reports hot-air convective drying of thin-layer fermented and non-fermented sugarcane bagasse. For this purpose, experiments were carried out in a laboratory-scale dryer assessing the effects of solid-state fermentation (SSF) on the drying kinetics of the processing material. The fermented sugarcane bagasse in SSF was obtained with the use of Kluyveromyces marxianus NRRL Y-7571. Drying experiments were carried out at 30, 35, 40 and 45 C, at volumetric air flow rates of 2 and 3 m{sup 3} h{sup -1}. The ability of ten different thin-layer mathematical models was evaluated towards representing the experimental drying profiles obtained. Results showed that the fermented sugarcane bagasse presents a distinct, faster drying, behavior from that verified for the non-fermented material at the same conditions of temperature and volumetric air flow rate. It is shown that the fermented sugarcane bagasse presented effective diffusion coefficient values of about 1.3 times higher than the non-fermented material. A satisfactory agreement between experimental data and model results of the thin-layer drying of fermented and non-fermented sugarcane bagasse was achieved at the evaluated experimental conditions. (author)

  11. Analyzing a Vibrating Wire Transducer using Coupled Resonator Circuits

    Directory of Open Access Journals (Sweden)

    POP, S.

    2015-08-01

    Full Text Available This paper intends to be an approach on the vibrating wire transducer from the perspective of the necessary rules used for a correct measurement procedure. There are several studies which analyze the vibrating wire transducer as a mechanical system. However, a comparative time-domain analysis between the mechanical and the electrical model is lacking. The transducer analysis is based on a theoretical analysis of the equivalent circuit, on both excitation and response time intervals. The electrical model consists of two magnetic coupled resonating circuits. When connected to an excitation source, there will be an energy transfer from the coil to the wire. The maximum energy transfer will occur at the vibrating wire's frequency of resonance. Using the transient regime analysis, it has been proven that, in the response time interval - when the wire vibrates freely, the current through the circuit that models the wire describes the oscillating movement of the wire. A complex signal is obtained, that contains both coil's and wire's frequencies of resonance, strongly dependent with theirs parasitic elements. The mathematical analysis highlights the similarity between mechanical and electrical model and the procedures in order to determine the wire frequency of resonance from the output signal.

  12. Investigating the magnetic field-dependent conductivity in magnetite thin films by modelling the magnetorefractive effect.

    Science.gov (United States)

    Kelley, Chris S; Naughton, James; Benson, Emma; Bradley, Ruth C; Lazarov, Vlado K; Thompson, Sarah M; Matthew, Jim A D

    2014-01-22

    A model of the magnetorefractive effect is developed for metallic oxides which allows the MRE to be used to study the magnetic dependence of their transport and phononic properties. This model is successfully applied to Fe3O4 and compared to experiments on a series of magnetite thin films of varying thickness (10, 18, 37, 64 and 110 nm) deposited on MgO(111) substrates. Reflection spectra were modelled as a function of film thickness, calculated from the Fresnel equations using an Fe3O4 dielectric function consisting of Drude, hopping, phononic and d-s transition conductivity processes. The reflectivity spectra of the different thickness films are reasonably reproduced by the model and reveal that the Fe3O4 18.5 μm phonon peak is shifted to a shorter wavelength in the thin films, approaching the bulk value for t > 110 nm. The MRE spectra are modelled by introducing a magnetic field dependence to the hopping and phononic terms, where previous models have considered the magnetic dependence to be on the Drude term only. In addition, the position of the Fe3O4 18.5 μm phonon peak was also found to shift in energy in the applied magnetic field by 0.05 μm. These results demonstrate the potential for using the MRE technique for probing the underlying magnetoelectronic properties of thin film oxides in a quick and non-destructive way.

  13. Modeling of end-pumped Yb:YAG thin-disk lasers with nonuniform temperature distribution.

    Science.gov (United States)

    Zhu, Guangzhi; Zhu, Xiao; Zhu, Changhong; Shang, Jianli; Wan, Hailin; Guo, Fei; Qi, Lijun

    2012-05-10

    A plane wave model with nonuniform temperature distribution in the thin-disk crystal is developed to describe the dynamic behavior of an end-pumped Yb:YAG thin-disk laser. A set of couple-rate equations and 2D stationary heat-conduction equations are derived. The stable temperature distribution in the disk crystal is calculated using a numerical iterative method. The analytic expression is capable of dealing with more practical laser systems than previous works on this subject as it allows for nonuniform temperature distribution in the disk crystal. Based on these results, we examined laser output intensity as a function of pump intensity, dopant concentration, resonator coupler reflectivity, crystal thickness and temperature of cooling liquid.

  14. Nanogoniometry with scanning force microscopy: a model study of CdTe thin films.

    Science.gov (United States)

    Palacios-Lidón, Elisa; Guanter, Luis; Zúñiga-Pérez, Jesús; Muñoz-Sanjosé, Vicente; Colchero, Jaime

    2007-03-01

    In this paper scanning force microscopy is combined with simple but powerful data processing to determine quantitatively, on a sub-micrometer scale, the orientation of surface facets present on crystalline materials. A high-quality scanning force topography image is used to determine an angular histogram of the surface normal at each image point. In addition to the known method for the assignment of Miller indices to the facets appearing on the surface, a quantitative analysis is presented that allows the characterization of the relative population and morphological quality of each of these facets. Two different CdTe thin films are used as model systems to probe the capabilities of this method, which enables further information to be obtained about the thermodynamic stability of particular crystallographic facets. The method, which is referred to as nanogoniometry, will be a powerful tool to study in detail the surface of crystalline materials, particularly thin films, with sub-micrometer resolution.

  15. Degradation and device physics modeling of SWCNT/CdTe thin film photovoltaics

    Science.gov (United States)

    Houshmand, Mohammad; Zandi, M. Hossein; Gorji, Nima E.

    2015-12-01

    We propose single walled carbon nanotubes as the n-type window partner of CdTe layer in a conventional CdS/CdTe thin film solar cells. The semiconductor nanotubes have superior optical and electrical properties i.e. controllable high band gap, being highly conductive and non-diffusive (not mobile). We modeled current-voltage characteristics of hybrid SWCNT/CdTe structure using Sah-Noyce-Shockley theory instead of Schottky barrier theory. The former theory is rather strong since it is based on carrier transport in the depletion region of a pn junction and considers the defect density within the depletion width. Also, a time dependent approach is used to simulate the degradation of device metrics under bias, illumination and temperature. It is discussed how a nanolayer can reduce the degradation rate of a thin film solar cell by surpassing grain boundaries and mobile ions migration towards junction.

  16. Characterization and modeling tools for light management in heterogeneous thin film layers

    Science.gov (United States)

    Le Rouzo, J.; Duché, D.; Ruiz, C. M.; Thierry, F.; Carlberg, M.; Berginc, G.; Pasquinelli, M.; Simon, J.-J.; Escoubas, L.; Flory, F.

    2016-09-01

    The extraordinary progresses in the design and realization of structures in inorganic or organic thin films, whether or not including nanoparticles, make it possible to develop devices with very specific properties. Mastering the links between the macroscopic optical properties and the opto-geometrical parameters of these heterogeneous layers is thus a crucial issue. We propose to present the tools used to characterize and to model thin film layers, from an optical point of view, highlighting the interest of coupling both experimental and simulation studies for improving our knowledge on the optical response of the structure. Different examples of studies are presented on CIGS, Perovskite, P3HT:ZnO, PC70BM, organic layer containing metallic nanoparticles and colored solar cells.

  17. Analytical model for thin-film SOI PIN-diode leakage current

    Science.gov (United States)

    Schmidt, Andrei; Dreiner, Stefan; Vogt, Holger; Goehlich, Andreas; Paschen, Uwe

    2017-04-01

    An analytical model for the thin-film silicon-on-insulator pin-diode leakage current is presented. Particularly the back-gate potential influence on the leakage current is addressed. The two-dimensional Poisson equation is simplified and then solved including the influence of the back-gate potential. Subsequently the analytical model is verified by comparison with numerical simulation and measurements. For the verification of the model the dependence on the back-gate potential, reverse voltage, device geometry, doping concentration and -polarity is considered. In this procedure the interface recombination velocity is used as fitting parameter. The model verification shows an accurate modeling of the leakage current at full depletion in combination with a back-gate potential dependence. The usage of the model is limited to back-gate and reverse potentials close to full depletion state of the pin-diode.

  18. Modeling and simulation of the drying of thin sheets in a continuous infrared dryer

    Energy Technology Data Exchange (ETDEWEB)

    Dhib, R.; Broadbent, A.D.; Therien, N. (Sherbrooke Univ., PQ (Canada))

    1994-10-01

    A differential model describing the dynamics of the infrared drying process has been set up from mass and energy balances between the moving wet material, the radiant emitters, and the air forced inside the dryer. The objective of the study is to provide a predictive model that can be used to assess the dynamic behavior of the infrared drying of a thin sheet of porous material (e.g. paper or textile). The process output responses to changes in material velocity, heating power, and water content of the entering sheet are presented. Thin sheets of bleached cotton were used to calibrate the model, and experiments were conducted to cover the entire range of operating conditions of an infrared pilot-plant dryer. The model consists of a set of four coupled hyperbolic partial differential equations describing the variations of the air and web temperatures and humidities as a function of time and space along the dryer length. The model predictions agreed well with the experimental data. Model predictions using arithmetic averages for the parameters, and parameters correlated with operational variables, are also presented and discussed. 30 refs., 9 figs., 5 tabs.

  19. Dispersion model for optical thin films applicable in wide spectral range

    Science.gov (United States)

    Franta, Daniel; Nečas, David; Ohlídal, Ivan; Giglia, Angelo

    2015-09-01

    In the optics industry thin film systems are used to construct various interference devices such as antireflective coatings, high-reflectance mirrors, beam splitters and filters. The optical characterization of complex optical systems can not be performed by measurements only in the short spectral range in which the interference devices will be employed because the measured data do not contain sufficient information about all relevant parameters of these systems. The characterization of film materials requires the extension of the spectral range of the measurements to the IR region containing phonon absorption and to the UV region containing the electronic excitations. However, this leads to necessity of a dispersion model suitable for the description of the dielectric response in the wide spectral range. Such model must respect the physical conditions following from theory of dispersion, particularly Kramers-Kronig relations and integrability imposed by sum rules. This work presents the construction of a universal dispersion model composed from individual contributions representing both electronic and phonon excitations. The efficiency of presented model is given by the fact that all the contributions are described by analytical expressions. It is shown that the model is suitable for precise modeling of spectral dependencies of optical constants of a broad class of materials used in the optical industry for thin film systems such as MgF2, SiO2, Al2O3, HfO2, Ta2O5 and TiO2 in the spectral range from far IR to vacuum UV.

  20. A Transverse Dynamic Deflection Model for Thin Plate Made of Saturated Porous Materials

    Science.gov (United States)

    Feng-xi, Zhou; Xiao-lin, Cao

    2016-10-01

    In this article, a transverse dynamic deflection model is established for thin plate made of saturated porous materials. Based on the Biot's model for fluid-saturated porous media, using the Love-Kirchhoff hypothesis, the governing equations of transverse vibrations of fluid-saturated poroelastic plates are derived in detail, which take the inertial, fluid viscous, mechanical couplings, compressibility of solid, and fluid into account. The free vibration and forced vibration response of a simply supported poroelastic rectangular plate is obtained by Fourier series expansion method. Through numerical examples, the effect of porosity and permeability on the dynamic response, including the natural frequency, amplitude response, and the resonance areas is assessed.

  1. Atomically thin spherical shell-shaped superscatterers based on a Bohr model.

    Science.gov (United States)

    Li, Rujiang; Lin, Xiao; Lin, Shisheng; Liu, Xu; Chen, Hongsheng

    2015-12-18

    Graphene monolayers can be used for atomically thin three-dimensional shell-shaped superscatterer designs. Due to the excitation of the first-order resonance of transverse magnetic (TM) graphene plasmons, the scattering cross section of the bare subwavelength dielectric particle is enhanced significantly by five orders of magnitude. The superscattering phenomenon can be intuitively understood and interpreted with a Bohr model. In addition, based on the analysis of the Bohr model, it is shown that contrary to the TM case, superscattering is hard to achieve by exciting the resonance of transverse electric (TE) graphene plasmons due to their poor field confinements.

  2. Alternate model of Chladni figures for the circular homogenous thin plate case with open boundaries

    Science.gov (United States)

    Trejo-Mandujano, H. A.; Mijares-Bernal, G.; Ordoñez-Casanova, E. G.

    2015-01-01

    The wave equation is a direct but a complex approach to solve analytically for the Chladni figures, mainly because of the complications that non-smooth and open boundary conditions impose. In this paper, we present an alternate solution model based on the principle of Huygens-Fresnel and on the ideas of Bohr for the hydrogen atom. The proposed model has been implemented numerically and compared, with good agreement, to our own experimental results for the case of a thin homogenous circular plate with open boundaries.

  3. Improved concept models for straight thin-walled columns with box cross section

    Institute of Scientific and Technical Information of China (English)

    Yu-cheng LIU

    2008-01-01

    This paper focuses on developing improved concept models for straight thin-walled box sectional columns which can better predict the peak crushing force that occurs during crashworthiness analyses.We develop a nonlinear translational spring based on previous research and apply such a spring element to build the enhanced concept models.The work presented in this article is developed on the basis of the publication of the author(Liu and Day,2006b)and has been applied in a crashworthiness design issue,which is presented by the author in another paper(Liu,2008).

  4. Optimization of the Single Staggered Wire and Tube Heat Exchanger

    Directory of Open Access Journals (Sweden)

    Arsana I Made

    2016-01-01

    Full Text Available Wire and tube heat exchanger consists of a coiled tube, and wire is welded on the two sides of it in normal direction of the tube. Generally,wire and tube heat exchanger uses inline wire arrangement between the two sides, whereas in this study, it used staggered wire arrangement that reduces the restriction of convection heat transfer. This study performed the optimization of single staggered wire and tube heat exchanger to increase the capacity and reduce the mass of the heat exchanger. Optimization was conducted with the Hooke-Jeeves method, which aims to optimize the geometry of the heat exchanger, especially on the diameter (dw and the distance between wires (pw. The model developed to present heat transfer correlations on single staggered wire and tube heat exchanger was valid. The maximum optimization factor obtained when the diameter wire was 0.9 mm and the distance between wires (pw was 11 mm with the fref value = 1.5837. It means that the optimized design only using mass of 59,10 % and could transfer heat about 98,5 % from the basis design.

  5. Effect of Tension on Friction Coefficient Between Lining and Wire Rope with Low Speed Sliding

    Institute of Scientific and Technical Information of China (English)

    PENG Yu-xing; ZHU Zhen-cai; CHEN Guo-an; CAO Guo-hua

    2007-01-01

    In order to obtain the exact friction coefficient between lining and wire rope, the tension of wire rope is studied as a factor which affects this coefficient. A mechanical model of a wire rope subjected to axial load was established to determine the torque of the wire rope. The contact motion between lining and wire rope was regarded as a screw rotation and the axial force of the lining resulting from the torque of the wire rope was analyzed. Theoretical formulas relating tension of the wire rope and the friction coefficient was obtained. Experiments between lining and wire rope with low sliding speed were carried out with friction tester made by us. Experimental results show that increment of the friction coefficient is proportional to that of the tension of the wire rope with a low sliding speed. The experimental results agree with the theoretical calculation; the errors are less than 6%, which proves the validity of the theoretical model.

  6. Fluorescent silver nanoparticles via exploding wire technique

    Indian Academy of Sciences (India)

    Alqudami Abdullah; S Annapoorni

    2005-11-01

    Aqueous solution containing spherical silver nanoparticles of 20–80 nm size have been generated using a newly developed novel electro-exploding wire (EEW) technique where thin silver wires have been exploded in double distilled water. Structural properties of the resulted nanoparticles have been studied by means of X-ray diffractometer (XRD) and transmission electron microscopy (TEM). The absorption spectrum of the aqueous solution of silver nanoparticles showed the appearance of a broad surface plasmon resonance (SPR) peak centered at a wavelength of 390 nm. The theoretically generated SPR peak seems to be in good agreement with the experimental one. Strong green fluorescence emission was observed from the water-suspended silver nanoparticles excited with light of wavelengths 340, 360 and 390 nm. The fluorescence of silver nanoparticles could be due to the excitation of the surface plasmon coherent electronic motion with the small size effect and the surface effect considerations.

  7. Static analysis of ultra-thin beams based on a semi-continuum model

    Institute of Scientific and Technical Information of China (English)

    Cheng Li; Zhi-Jun Zheng; Ji-Lin Yu; C.W.Lim

    2011-01-01

    A linear semi-continuum model with discrete atomic layers in the thickness direction was developed to investigate the bending behaviors of ultra-thin beams with nanoscale thickness.The theoretical results show that the deflection of an ultra-thin beam may be enhanced or reduced due to different relaxation coefficients.If the relaxation coefficient is greater/less than one,the deflection of micro/nano-scale structures is enhanced/reduced in comparison with macro-scale structures.So,two opposite types of size-dependent behaviors are observed and they are mainly caused by the relaxation coefficients.Comparisons with the classical continuum model,exact nonlocal stress model and finite element model (FEM) verify the validity of the present semi-continuum model.In particular,an explanation is proposed in the debate whether the bending stiffness of a micro/nano-scale beam should be greater or weaker as compared with the macro-scale structures.The characteristics of bending stiffness are proved to be associated with the relaxation coefficients.

  8. Desorption isotherms and mathematical modeling of thin layer drying kinetics of tomato

    Science.gov (United States)

    Belghith, Amira; Azzouz, Soufien; ElCafsi, Afif

    2016-03-01

    In recent years, there is an increased demand on the international market of dried fruits and vegetables with significant added value. Due to its important production, consumption and nutrient intake, drying of tomato has become a subject of extended and varied research works. The present work is focused on the drying behavior of thin-layer tomato and its mathematical modeling in order to optimize the drying processes. The moisture desorption isotherms of raw tomato were determined at four temperature levels namely 45, 50, 60 and 65 °C using the static gravimetric method. The experimental data obtained were modeled by five equations and the (GAB) model was found to be the best-describing these isotherms. The drying kinetics were experimentally investigated at 45, 55 and 65 °C and performed at air velocities of 0.5 and 2 m/s. In order to investigate the effect of the exchange surface on drying time, samples were dried into two different shapes: tomato halves and tomato quarters. The impact of various drying parameters was also studied (temperature, air velocity and air humidity). The drying curves showed only the preheating period and the falling drying rate period. In this study, attention was paid to the modeling of experimental thin-layer drying kinetics. The experimental results were fitted with four different models.

  9. Reusable Hot-Wire Cable Cutter

    Science.gov (United States)

    Pauken, Michael T.; Steinkraus, Joel M.

    2010-01-01

    holds it in position. The leads of the nichrome wire are attached to screw terminals that connect them to power leads. A bayonet plug mounted at the bottom of the rectangular block connects the power leads to a relay circuit. A thin aluminum shell encloses the entire structure, leaving access points to attach to the bayonet plug and to feed a cable into the cylinder. The access holes for the deployment cable are a smaller diameter than the nichrome coil to prevent the cable from coming in direct contact with the nichrome when loaded. It uses the same general method of severing a cable with a heated wire as was used previously, but implements it in such a way that it is more reliable and less prone to failure. It creates a mechanism to create repeatability that was nonexistent in the previous method.

  10. Random forest models of the retention constants in the thin layer chromatography

    CERN Document Server

    Kursa, Miron B; Rudnicki, Witold R

    2011-01-01

    In the current study we examine an application of the machine learning methods to model the retention constants in the thin layer chromatography (TLC). This problem can be described with hundreds or even thousands of descriptors relevant to various molecular properties, most of them redundant and not relevant for the retention constant prediction. Hence we employed feature selection to significantly reduce the number of attributes. Additionally we have tested application of the bagging procedure to the feature selection. The random forest regression models were built using selected variables. The resulting models have better correlation with the experimental data than the reference models obtained with linear regression. The cross-validation confirms robustness of the models.

  11. Absorption coefficient modeling of microcrystalline silicon thin film using Maxwell-Garnett effective medium theory.

    Science.gov (United States)

    Chen, Sheng-Hui; Wang, Hsuan-Wen; Chang, Ting-Wei

    2012-03-12

    Considering the Mott-Davis density of state model and Rayleigh scattering effect, we present an approach to model the absorption profile of microcrystalline silicon thin films in this paper. Maxwell-Garnett effective medium theory was applied to analyze the absorption curves. To validate the model, several experimental profiles have been established and compared with those results from the model. With the assistance of the genetic algorithm, our results show that the absorption curves from the model are in good agreement with the experiments. Our findings also indicate that, as the crystal volume fraction increases, not only do the defects in amorphous silicon reduce, but the bulk scattering effect is gradually enhanced as well.

  12. Low cost, formable, high T(sub c) superconducting wire

    Science.gov (United States)

    Smialek, James L. (Inventor)

    1991-01-01

    A ceramic superconductivity part such as a wire is produced through the partial oxidation of a specially formulated copper alloy in the core. The alloys contain low level quantities of rare earth and alkaline earth dopant elements. Upon oxidation at high temperature, superconducting oxide phases are formed as a thin film.

  13. Beam Position and Phase Monitor - Wire Mapping System

    Energy Technology Data Exchange (ETDEWEB)

    Watkins, Heath A [Los Alamos National Laboratory; Shurter, Robert B. [Los Alamos National Laboratory; Gilpatrick, John D. [Los Alamos National Laboratory; Kutac, Vincent G. [Los Alamos National Laboratory; Martinez, Derwin [Los Alamos National Laboratory

    2012-04-10

    The Los Alamos Neutron Science Center (LANSCE) deploys many cylindrical beam position and phase monitors (BPPM) throughout the linac to measure the beam central position, phase and bunched-beam current. Each monitor is calibrated and qualified prior to installation to insure it meets LANSCE requirements. The BPPM wire mapping system is used to map the BPPM electrode offset, sensitivity and higher order coefficients. This system uses a three-axis motion table to position the wire antenna structure within the cavity, simulating the beam excitation of a BPPM at a fundamental frequency of 201.25 MHz. RF signal strength is measured and recorded for the four electrodes as the antenna position is updated. An effort is underway to extend the systems service to the LANSCE facility by replacing obsolete electronic hardware and taking advantage of software enhancements. This paper describes the upgraded wire positioning system's new hardware and software capabilities including its revised antenna structure, motion control interface, RF measurement equipment and Labview software upgrades. The main purpose of the wire mapping system at LANSCE is to characterize the amplitude response versus beam central position of BPPMs before they are installed in the beam line. The wire mapping system is able to simulate a beam using a thin wire and measure the signal response as the wire position is varied within the BPPM aperture.

  14. Dispersion-model-free determination of optical constants: application to materials for organic thin film devices.

    Science.gov (United States)

    Flämmich, Michael; Danz, Norbert; Michaelis, Dirk; Bräuer, Andreas; Gather, Malte C; Kremer, Jonas H-W M; Meerholz, Klaus

    2009-03-10

    We describe a method to determine the refractive index and extinction coefficient of thin film materials without prior knowledge of the film thickness and without the assumption of a dispersion model. A straightforward back calculation to the optical parameters can be performed starting from simple measurements of reflection and transmission spectra of a 100-250 nm thick supported film. The exact film thickness is found simultaneously by fulfilling the intrinsic demand of continuity of the refractive index as a function of wavelength. If both the layer and the substrate are homogeneous and isotropic media with plane and parallel interfaces, effects like surface roughness, scattering, or thickness inhomogeneities can be neglected. Then, the accuracy of the measurement is approximately 10(-2) and 10(-3) for the refractive index and the extinction coefficient, respectively. The error of the thin film thickness determination is well below 1 nm. Thus this technique is well suited to determine the input parameters for optical simulations of organic thin film devices, such as organic light-emitting diodes (OLEDs) or organic photovoltaic (OPV) cells. We apply the method to the electroluminescent polymer poly(2,5-dioctyl-p-phenylene vinylene) (PDO-PPV) and show its applicability by comparing the measured and calculated reflection and transmission spectra of OLED stacks with up to five layers.

  15. A liquid-like model for the morphology evolution of ion bombarded thin films

    Energy Technology Data Exchange (ETDEWEB)

    Repetto, L., E-mail: luca.repetto@unige.it [Department of Physics and Nanomed Labs, Università di Genova, Via Dodecaneso 33, 16146 Genova (Italy); Lo Savio, R. [Department of Physics and Nanomed Labs, Università di Genova, Via Dodecaneso 33, 16146 Genova (Italy); Šetina Batič, B. [Inštitut Za Kovinske Materiale in Tehnologije, Lepi pot 11, 1000 Ljubljana (Slovenia); Firpo, G.; Angeli, E.; Valbusa, U. [Department of Physics and Nanomed Labs, Università di Genova, Via Dodecaneso 33, 16146 Genova (Italy)

    2015-07-01

    Thin solid films exposed to ion irradiation exhibit a peculiar evolution that can differ substantially from what is observed for bulk samples. The phenomenology of the patterns that self-organize on the substrate is very rich, with morphologies that display several degrees of order upon the modification of initial film characteristics and irradiation parameters. This richness paves the way for the fabrication of novel functional surfaces, but it is also an indication of the complexity of the underlying driving mechanisms. A remarkable simplification for the comprehension of these phenomena can come from the noteworthy similarity of the obtained patterns with those showing up when liquids dewet from their substrates. Here, we analyze the possibility to apply a liquid-like model to explain the morphology evolution of ion bombarded thin films for the whole phenomenology showing up in experiments. In establishing this connection between liquids and ion bombarded thin films, we propose to use also for liquids the insight gained for our system with recent experiments that stress the importance of the substrate topography for the selection of the dewetting mechanism. If confirmed, this result would lead to a reconsideration of the importance of capillary waves in spinodal dewetting, and will help to understand the low reproducibility of the related experimental results.

  16. COLD ROLLING ORTHODONTIC WIRES OF AUSTENITIC STAINLESS STEEL AISI 304

    Directory of Open Access Journals (Sweden)

    Rodrigo Santos Messner

    2013-03-01

    Full Text Available Austenitic stainless steels wires are widely used in the final stages of orthodontic treatment. The objective of this paper is to study the process of conformation of rectangular wires from round wires commercial austenitic stainless steel AISI 304 by the process of cold rolling. The wire quality is evaluated by means of dimensional analysis, microhardness measurements, tensile strength and fractographic analysis of the wires subjected to tensile tests. Also a study on the application of finite element method to simulate the process, comparing the force and rolling stress obtained in the rolling is done. The simulation results are consistent with those obtained in the actual process and the rolled wires show ductile fracture, tensile strength and dimensional variations appropriate to orthodontic standards. The fracture morphology shows the model cup-cone type besides the high deformation and hardness inherent in the cold rolling process.

  17. Electric wiring domestic

    CERN Document Server

    Coker, A J

    1992-01-01

    Electric Wiring: Domestic, Tenth Edition, is a clear and reliable guide to the practical aspects of domestic electric wiring. Intended for electrical contractors, installation engineers, wiremen and students, its aim is to provide essential up to date information on modern methods and materials in a simple, clear, and concise manner. The main changes in this edition are those necessary to bring the work into line with the 16th Edition of the Regulations for Electrical Installations issued by the Institution of Electrical Engineers. The book begins by introducing the basic features of domestic

  18. Wiring and lighting

    CERN Document Server

    Kitcher, Chris

    2013-01-01

    Wiring and Lighting provides a comprehensive guide to DIY wiring around the home. It sets out the regulations and legal requirements surrounding electrical installation work, giving clear guidelines that will enable the reader to understand what electrical work they are able to carry out, and what the testing and certification requirements are once the work is completed. Topics covered include: Different types of circuits; Types of cables and cable installation under floors and through joists; Isolating, earthing and bonding; Accessory boxes and fixings; Voltage bands; Detailed advice on safe

  19. Modern wiring practice

    CERN Document Server

    Steward, W E

    2012-01-01

    Continuously in print since 1952, Modern Wiring Practice has now been fully revised to provide an up-to-date source of reference to building services design and installation in the 21st century. This compact and practical guide addresses wiring systems design and electrical installation together in one volume, creating a comprehensive overview of the whole process for contractors and architects, as well as electricians and other installation engineers. Best practice is incorporated throughout, combining theory and practice with clear and accessible explanation, all

  20. Dissonance-Based Eating Disorder Prevention Program Reduces Reward Region Response to Thin Models; How Actions Shape Valuation.

    Directory of Open Access Journals (Sweden)

    Eric Stice

    Full Text Available Research supports the effectiveness of a dissonance-based eating disorder prevention program wherein high-risk young women with body dissatisfaction critique the thin ideal, which reduces pursuit of this ideal, and the theory that dissonance induction contributes to these effects. Based on evidence that dissonance produces attitudinal change by altering neural representation of valuation, we tested whether completing the Body Project would reduce response of brain regions implicated in reward valuation to thin models. Young women with body dissatisfaction were randomized to this intervention or an educational control condition, completing assessments and fMRI scans while viewing images of thin versus average-weight female models at pre and post. Whole brain analyses indicated that, compared to controls, Body Project participants showed greater reductions in caudate response to images of thin versus average-weight models, though participants in the two conditions showed pretest differences in responsivity of other brain regions that might have contributed to this effect. Greater pre-post reductions in caudate and putamen response to thin models correlated with greater reductions in body dissatisfaction. The finding that the Body Project reduces caudate response to thin models provides novel preliminary evidence that this intervention reduces valuation of media images thought to contribute to body dissatisfaction and eating disorders, providing support for the intervention theory by documenting that this intervention alters an objective biological outcome.

  1. Dissonance-Based Eating Disorder Prevention Program Reduces Reward Region Response to Thin Models; How Actions Shape Valuation.

    Science.gov (United States)

    Stice, Eric; Yokum, Sonja; Waters, Allison

    2015-01-01

    Research supports the effectiveness of a dissonance-based eating disorder prevention program wherein high-risk young women with body dissatisfaction critique the thin ideal, which reduces pursuit of this ideal, and the theory that dissonance induction contributes to these effects. Based on evidence that dissonance produces attitudinal change by altering neural representation of valuation, we tested whether completing the Body Project would reduce response of brain regions implicated in reward valuation to thin models. Young women with body dissatisfaction were randomized to this intervention or an educational control condition, completing assessments and fMRI scans while viewing images of thin versus average-weight female models at pre and post. Whole brain analyses indicated that, compared to controls, Body Project participants showed greater reductions in caudate response to images of thin versus average-weight models, though participants in the two conditions showed pretest differences in responsivity of other brain regions that might have contributed to this effect. Greater pre-post reductions in caudate and putamen response to thin models correlated with greater reductions in body dissatisfaction. The finding that the Body Project reduces caudate response to thin models provides novel preliminary evidence that this intervention reduces valuation of media images thought to contribute to body dissatisfaction and eating disorders, providing support for the intervention theory by documenting that this intervention alters an objective biological outcome.

  2. Modeling of the flow-solidification interaction in thin slab casting

    Science.gov (United States)

    Vakhrushev, A.; Wu, M.; Ludwig, A.; Tang, Y.; Hackl, G.; Nitzl, G.

    2012-07-01

    A key issue for modelling the thin slab casting (TSC) is to consider the evolution of the solid shell, which strongly interacts with the turbulent flow and in the meantime is subject to continuous deformation due to the funnel shape (curvature) of the mould. Here an enthalpy-based mixture solidification model with consideration of turbulent flow [Prescott and Incropera, ASME HTD, vol. 280, 1994, pp. 59] is employed, and further enhanced to include the deforming solid shell. The solid velocity in the fully-solidified strand shell and partially-solidified mushy zone is estimated by solving the Laplace's equation. Primary goals of this work are to examine the sensitivity of the modelling result to different model implementation schemes, and to explore the importance of the deforming and moving solid shell in the solidification. Therefore, a 2D benchmark, to mimic the solidification and deformation behaviour of the thin slab casting, is firstly simulated and evaluated. An example of 3D TSC is also presented. Due to the limitation of the current computation resources additional numerical techniques like parallel computing and mesh adaptation are necessarily applied to ensure the calculation accuracy for the full-3D TSC.

  3. Simulation of polycrystalline silicon thin film solar cells - model calibration and sensitivity analysis

    Energy Technology Data Exchange (ETDEWEB)

    Teodoreanu, Ana-Maria; Leendertz, Caspar; Sontheimer, Tobias; Rech, Bernd [Helmholtz-Zentrum Berlin, Kekulestr. 5. 12489 Berlin (Germany)

    2011-07-01

    To gain a better insight into the efficiency-limiting processes in polycrystalline silicon (poly-Si) thin film solar cells, we developed a simulation model for the J-V characteristics and minority carrier lifetime based on experimental results using the numerical 1D simulation program AFORS-HET. The calibration of the model has been achieved through simultaneously fitting the measured dark and light J-V curves of twelve poly-Si thin film minimodules with dissimilar thickness and absorber doping concentration. Effective defect density, capture cross section products of 10..100 cm{sup -1} have been determined in the poly-Si absorber by this procedure. Transient photoconductance decay measurements of the poly-Si absorbers have also been conducted in the low injection regime (4.5.10{sup 14} cm{sup -3}). High lifetimes of 100 {mu} s have been found which can be explained within our simulation model by field effect passivation. Furthermore simulations indicate that this field effect leads to a strong injection-dependence of carrier lifetime in the operation range of the solar cell. The sensitivity analysis performed with our calibrated model shows that the defects in the absorber layer are crucial for the cell efficiency. Thus, the improvement of the emitter and back surface field layers becomes important only if the absorber itself is of better quality. Moreover we discuss the optimum absorber thickness subject to different doping levels and absorber defect densities.

  4. Modeling and characterization of extremely thin absorber (eta) solar cells based on ZnO nanowires.

    Science.gov (United States)

    Mora-Seró, Iván; Giménez, Sixto; Fabregat-Santiago, Francisco; Azaceta, Eneko; Tena-Zaera, Ramón; Bisquert, Juan

    2011-04-21

    Extremely thin absorber (eta)-solar cells based on ZnO nanowires sensitized with a thin layer of CdSe have been prepared, using CuSCN as hole transporting material. Samples with significantly different photovoltaic performance have been analyzed and a general model of their behavior was obtained. We have used impedance spectroscopy to model the device discriminating the series resistance, the role of the hole conducting material CuSCN, and the interface process. Correlating the impedance analysis with the microstructural properties of the solar cell interfaces, a good description of the solar cell performance is obtained. The use of thick CdSe layers leads to high recombination resistances, increasing the open circuit voltage of the devices. However, there is an increase of the internal recombination in thick light absorbing layers that also inhibit a good penetration of CuSCN, reducing the photocurrent. The model will play an important role on the optimization of these devices. This analysis could have important implications for the modeling and optimization of all-solid devices using a sensitizing configuration.

  5. Numerical Simulation of Wire-Coating

    DEFF Research Database (Denmark)

    Wapperom, Peter; Hassager, Ole

    1999-01-01

    A finite element program has been used to analyze the wire-coating process of an MDPE melt. The melt is modeled by a nonisothermal Carreau model. The emphasis is on predicting an accurate temperature field. Therefore, it is necessary to include the heat conduction in the metal parts. A comparison...

  6. Introduction of CORC® wires: highly flexible, round high-temperature superconducting wires for magnet and power transmission applications

    Science.gov (United States)

    Weiss, Jeremy D.; Mulder, Tim; ten Kate, Herman J.; van der Laan, Danko C.

    2017-01-01

    Conductor on Round Core (CORC®) technology has achieved a long sought-after benchmark by enabling the production of round, multifilament, (RE)Ba2Ca3O7-x coated conductors with practical current densities for use in magnets and power applications. Recent progress, including the demonstration of engineering current density beyond 300 Amm-2 at 4.2 K and 20 T, indicates that CORC® cables are a viable conductor for next generation high field magnets. Tapes with 30 μm substrate thickness and tape widths down to 2 mm have improved the capabilities of CORC® technology by allowing the production of CORC® wires as thin as 3 mm in diameter with the potential to enhance the engineering current density further. An important benefit of the thin CORC® wires is their improved flexibility compared to thicker (7-8 mm diameter) CORC® cables. Critical current measurements were carried out on tapes extracted from CORC® wires made using 2 and 3 mm wide tape after bending the wires to various diameters from 10 to 3.5 cm. These thin wires are highly flexible and retain close to 90% of their original critical current even after bending to a diameter of 3.5 cm. A small 5-turn solenoid was constructed and measured as a function of applied magnetic field, exhibiting an engineering current density of 233 Amm-2 at 4.2 K and 10 T. CORC® wires thus form an attractive solution for applications between 4.2 and 77 K, including high-field magnets that require high current densities with small bending diameters, benefiting from a ready-to-use form (similar to NbTi and contrary to Nb3Sn wires) that does not require additional processing following coil construction.

  7. Radiation from mixed multi-planar wire arrays

    Energy Technology Data Exchange (ETDEWEB)

    Safronova, A. S.; Kantsyrev, V. L.; Esaulov, A. A.; Weller, M. E.; Shlyaptseva, V. V.; Shrestha, I.; Keim, S. F.; Stafford, A. [Physics Department, University of Nevada, Reno, Nevada 89557 (United States); Chuvatin, A. S. [Laboratoire de Physique des Plasmas, Ecole Polytechnique, 91128 Palaiseau (France); Coverdale, C. A. [Sandia National Laboratories, Albuquerque, New Mexico (United States); Apruzese, J. P. [Consultant to NRL through Engility Corp., Chantilly, Virginia 20151 (United States); Ouart, N. D.; Giuliani, J. L. [Naval Research Laboratory, Washington DC 20375 (United States)

    2014-03-15

    The study of radiation from different wire materials in wire array Z-pinch plasma is a very challenging topic because it is almost impossible to separate different plasmas at the stagnation. A new approach is suggested based on planar wire array (PWA) loads to assess this problem. Multi-planar wire arrays are implemented that consist of few planes, each with the same number of wires and masses but from different wire materials, arranged in parallel rows. In particular, the experimental results obtained with triple PWAs (TPWAs) on the UNR Zebra generator are analyzed with Wire Ablation Dynamics Model, non-local thermodynamic equilibrium kinetic model, and 2D radiation magneto-hydrodynamic to illustrate this new approach. In TPWAs, two wire planes were from mid-atomic-number wire material and another plane was from alloyed Al, placed either in the middle or at the edge of the TPWA. Spatial and temporal properties of K-shell Al and L-shell Cu radiations were analyzed and compared from these two configurations of TPWAs. Advantages of the new approach are demonstrated and future work is discussed.

  8. Design of Large Thinned Arrays Using Different Biogeography-Based Optimization Migration Models

    Directory of Open Access Journals (Sweden)

    Sotirios K. Goudos

    2016-01-01

    Full Text Available Array thinning is a common discrete-valued combinatorial optimization problem. Evolutionary algorithms are suitable techniques for above-mentioned problem. Biogeography-Based Optimization (BBO, which is inspired by the science of biogeography, is a stochastic population-based evolutionary algorithm (EA. The original BBO uses a linear migration model to describe how species migrate from one island to another. Other nonlinear migration models have been proposed in the literature. In this paper, we apply BBO with four different migration models to five different large array design cases. Additionally we compare results with five other popular algorithms. The problems dimensions range from 150 to 300. The results show that BBO with sinusoidal migration model generally performs better than the other algorithms. However, these results are considered to be indicative and do not generally apply to all optimization problems in antenna design.

  9. Simulation of ultra-thin sheet metal forming using phenomenological and crystal plasticity models

    Science.gov (United States)

    Adzima, F.; Manach, PY; Balan, T.; Tabourot, L.; Toutain, S.; Diot, JL

    2016-08-01

    Micro-forming of ultra-thin sheet metals raises numerous challenges. In this investigation, the predictions of state-of-the-art crystal plasticity (CP) and phenomenological models are compared in the framework of industrial bending-dominated forming processes. Sheet copper alloys 0.1mm-thick are considered, with more than 20 grains through the thickness. Consequently, both model approaches are valid on theoretical ground. The phenomenological models’ performance was conditioned by the experimental database used for parameter identification. The CP approach was more robust with respect to parameter identification, while allowing for a less flexible description of kinematic hardening, at the cost of finer mesh and specific grain-meshing strategies. The conditions for accurate springback predictions with CP-based models are investigated, in an attempt to bring these models at the robustness level required for industrial application.

  10. Prediction of Rolling Force Using AN Adaptive Neural Network Model during Cold Rolling of Thin Strip

    Science.gov (United States)

    Xie, H. B.; Jiang, Z. Y.; Tieu, A. K.; Liu, X. H.; Wang, G. D.

    Customers for cold rolled strip products expect the good flatness and surface finish, consistent metallurgical properties and accurate strip thickness. These requirements demand accurate prediction model for rolling parameters. This paper presents a set-up optimization system developed to predict the rolling force during cold strip rolling. As the rolling force has the very nonlinear and time-varying characteristics, conventional methods with simple mathematical models and a coarse learning scheme are not sufficient to achieve a good prediction for rolling force. In this work, all the factors that influence the rolling force are analyzed. A hybrid mathematical roll force model and an adaptive neural network have been improved by adjusting the adaptive learning algorithm. A good agreement between the calculated results and measured values verifies that the approach is applicable in the prediction of rolling force during cold rolling of thin strips, and the developed model is efficient and stable.

  11. Critical state model for magneto-elastic problem of thin superconducting disks

    Science.gov (United States)

    Huang, Chen-Guang; Yong, Hua-Dong; Zhou, You-He

    2013-07-01

    The magneto-elastic problem of a thin superconducting disk in a perpendicular magnetic field is analyzed with field-dependent critical current. We calculate numerically the body force distribution and discuss the field dependence of Jc on the magneto-elastic behavior during field ascent and descent for three critical state models: Bean, Kim, and exponential models. The results show that when considering a field dependence of Jc, the flux and remagnetization fronts have a larger moving speed towards the center of a disk relative to the Bean model. Simultaneously, the most dangerous stage of possible cracking for the disk will arrive early in the field decreasing stage. The magnetostriction loops are also presented during a full cycle of the applied field. It is interesting that the calculated magnetostriction loops for the Kim and exponential models are quite similar to the corresponding magnetostriction curves at low and high temperatures measured in the experiment.

  12. Cellular automaton modeling of ductile iron microstructure in the thin wall

    Directory of Open Access Journals (Sweden)

    A.A. Burbelko

    2011-10-01

    Full Text Available The mathematical model of the globular eutectic solidification in 2D was designed. Proposed model is based on the Cellular Automaton Finite Differences (CA-FD calculation method. Model has been used for studies of the primary austenite and of globular eutectic grains growth during the solidification of the ductile iron with different carbon equivalent in the thin wall casting. Model takes into account, among other things, non-uniform temperature distribution in the casting wall cross-section, kinetics of the austenite and graphite grains nucleation, and non-equilibrium nature of the interphase boundary migration. Solidification of the DI with different carbon equivalents was analyzed. Obtained results were compared with the solidification path calculated by CALPHAD method.

  13. Modeling the sensing characteristics of chemi-resistive thin film semi-conducting gas sensors.

    Science.gov (United States)

    Ghosh, Abhishek; Majumder, S B

    2017-08-30

    For chemi-resistive thin film gas sensors a generic theoretical model is proposed to predict the variation of sensor response with the operating temperature and thickness of the sensing film. A diffusion equation is formulated assuming that inflammable target gases move through the sensing film by Knudsen diffusion and react with the adsorbed oxygen following first-order kinetics. We have assumed a realistic non-linear variation between the conductance and test gas concentration and derived a general expression relating the sensor response to the operating temperature and thickness of the film. Assuming Langmuir adsorption kinetics, we have theoretically predicted the response and recovery transients during gas sensing using thin film sensing elements. It is predicted that for irreversible type sensing, the response time is reduced with an increase in test gas concentration, whereas for reversible sensing, the response time is independent of test gas concentration. For zinc oxide thin film sensors, an excellent match is obtained between the model prediction and experimental data for their thickness (122 nm to 380 nm) and temperature variation (200 °C to 325 °C) in 500 ppm carbon monoxide (CO) sensing. The maximum CO response% (∼53%) was achieved in 320 nm thick ZnO films. The conductance transients for response and recovery for CO sensing closely follow Langmuir adsorption kinetics and as predicted theoretically, indeed for irreversible sensing, the response time reduces from 350 s to 220 s with an increase in test gas concentration from 20 to 550 ppm. In the case of reversible sensing we found that the response time is ∼55 s irrespective of the CO gas concentration in the range of 5-500 ppm. The models developed in the present work are quite generic in nature and we have discussed their applicability to a wide variety of sensing materials with various types of surface morphologies.

  14. Modelling Defects Acceptors And Determination Of Electric Model From The Nyquist Plot And Bode In Thin Film CIGS

    Directory of Open Access Journals (Sweden)

    Demba Diallo

    2015-08-01

    Full Text Available Abstract The performance of the chalcopyrite material CuInGaSe2 CIGS used as an absorber layer in thin-film photovoltaic devices is significantly affected by the presence of native defects. Multivalent defects e.g. double acceptors or simple acceptor are important immaterial used in solar cell production in general and in chalcopyrite materials in particular. We used the thin film solar cell simulation software SCAPS to enable the simulation of multivalent defects with up to five different charge states.Algorithms enabled us to simulate an arbitrary number of possible states of load. The presented solution method avoids numerical inaccuracies caused by the subtraction of two almost equal numbers. This new modelling facility is afterwards used to investigate the consequences of the multivalent character of defects for the simulation of chalcopyrite based CIGS. The capacitance increase with the evolution of the number of defects C- f curves have found to have defect dependence.

  15. Development of multi-dimensional thermal hydraulic modeling using mixing factors for wire wrapped fuel pin bundles with inter-subassembly heat transfer in fast reactors

    Energy Technology Data Exchange (ETDEWEB)

    Nishimura, M.; Kamide, H.; Ohshima, H. [Power Reactor and Nuclear Fuel Development Corp., Oarai, Ibaraki (Japan). Oarai Engineering Center

    1996-10-01

    Temperature distributions in fuel subassemblies of fast reactors interactively affect heat transfer from center to outer region of the core (inter-subassembly heat transfer) and cooling capability of an inter-wrapper flow, as well as maximum cladding temperature. The prediction of temperature distribution in the sub-assembly is, therefore one of the important issues for the reactor safety assessment. To treat the complex phenomena in the core, a multi-dimensional thermal hydraulic analysis is the most promising method. From the studies on the multi-dimensional thermal hydraulic modeling for the fuel sub-assemblies, the modeling have been recommended through the analysis of sodium experiments using driver subassembly test rig PLANDTL-DHX and blanket subassembly test rig CCTL-CFR. Computations of steady states experiments in the test rigs using the above modeling showed quite good agreement to the experimental data. In the present study, the use of this modeling was extended to transient analyses, and its applicability was examined. Firstly, non-dimensional parameters used to determine the mixing factors were modified from the ones based on bundle-averaged values to the ones by local values. Secondly, a new threshold function was derived and introduced to cut off the mixing factor of thermal plumes under inertia force dominant conditions. In the results of this validation, the accuracy was comparable between the modeling and the experimental instrumentation. Thus the present modeling is capable of predicting the thermal hydraulic fields of the wire wrapped fuel pin bundles with inter-subassembly heat transfer under the conditions from rated steady operations to transitions toward natural circulation decay heat removal modes. (J.P.N.)

  16. Practical wiring in SI units

    CERN Document Server

    Miller, Henry A

    2013-01-01

    Practical Wiring, Volume 1 is a 13-chapter book that first describes some of the common hand tools used in connection with sheathed wiring. Subsequent chapters discuss the safety in wiring, cables, conductor terminations, insulating sheathed wiring, conductor sizes, and consumer's control equipments. Other chapters center on socket outlets, plugs, lighting subcircuits, lighting accessories, bells, and primary and secondary cells. This book will be very valuable to students involved in this field of interest.

  17. Analytical drain current model for amorphous IGZO thin-film transistors in abovethreshold regime

    Institute of Scientific and Technical Information of China (English)

    He Hongyu; Zheng Xueren

    2011-01-01

    An analytical drain current model is presented for amorphous In-Ga-Zn-oxide thin-film transistors in the above-threshold regime,assuming an exponential trap states density within the bandgap.Using a charge sheet approximation,the trapped and free charge expressions are calculated,then the surface potential based drain current expression is developed.Moreover,threshold voltage based drain current expressions are presented using the Taylor expansion to the surface potential based drain current expression.The calculated results of the surface potential based and threshold voltage based drain current expressions are compared with experimental data and good agreements are achieved.

  18. An Improved Thin Film Brick-Wall Model of Black Hole Entropy

    Institute of Scientific and Technical Information of China (English)

    LIU Wen-Biao; ZHAO Zheng

    2001-01-01

    We improve the brick-wall model to take only the contribution of a thin film near the event horizon into account. This improvement not only gives us a satisfactory result, but also avoids some drawbacks in the original brick wall method such as the little mass approximation, neglecting logarithm term, and taking the term L3 as the contribution of the vacuum surrounding a black hole. It is found that there is an intrinsic relation between the event horizon and the entropy. The event horizon is the characteristic of a black hole, so the entropy calculating of a black hole is also naturally related to its horizon.

  19. Perfectionism in Body Dissatisfaction, Sociocultural Influence of the Thinness model and Symptoms of Eating Disorders

    Directory of Open Access Journals (Sweden)

    Karina Franco Paredes

    2011-09-01

    Full Text Available The purpose of this study was to assess if perfectionism components explained body dissatisfaction (BD, sociocultural influences of aesthetic model (SIAM and symptoms of eating disorders (ED. The sample comprised 30 women with Bulimia Nervosa (BN, 35 women with Eating Disorder not Otherwise Specified (EDNOS and 63 women without ED. A regression analysis showed that concern over mistakes (CM and doubt about actions explained BD and SIAM in the BN sample; while concern over mistakes only explained SIAM in the EDNOS sample. These findings evidence that two perfectionism components contribute to vulnerability of thinness ideal and BD among women, which constitute two important risk factors for ED.

  20. 线框模型中二次曲面的识别%Quadric Surface Identification from Wire-Frame Models

    Institute of Scientific and Technical Information of China (English)

    赵军; 高满屯; 王三民

    2011-01-01

    定义关联两曲线间的夹角和由3条关联曲线确定二次曲面,提出适用于曲面的回路搜索最小转角法,且利用它并辅以矢量混合积验证搜索曲面上最小回路的方法.实现从线框模型中选择任意一条曲线就能够搜索到包含它的所有潜在表面回路,突破以往回路搜索方法中只能从某方向极值点开始的束缚,为线框模型表面识别中将含曲线表面与不含曲线表面分治识别奠定基础,算法可处理含有任意位置的二次曲表面的线框模型,并能较准确地判别二次曲面的类型.%The angle between two connected curves on same quadric is defined and two minimum internal angle algorithms( MIA_cw and MIA_ccw) that can be applied to quadric surfaces are proposed. When a circle is searched by MIA_cw or MIA_ccw, the vector mixed product is employed to verify whether the circle is a candidate surface or not. In the proposed method, no matter which curved edge of wire-frame model is chosen, the candidate surface containing it can be obtained. Thus, it removes the restriction on the start edge in searching candidate surface in existing methods. The candidate surface with curves is separated from those without curves by the proposed method and different algorithms can be used for these two kinds of candidate surfaces. And it requires less time than the one using one algorithm to search all candidate surfaces (including quadric surface and plane surface). Furthermore, the proposed method can deal with the 3D wire-frame models with no restriction on the axis of the quadric surface and identify the type of the quadric.

  1. 3D Wire 2015

    DEFF Research Database (Denmark)

    Jordi, Moréton; F, Escribano; J. L., Farias

    This document is a general report on the implementation of gamification in 3D Wire 2015 event. As the second gamification experience in this event, we have delved deeply in the previous objectives (attracting public areas less frequented exhibition in previous years and enhance networking) and ha......, improves socialization and networking, improves media impact, improves fun factor and improves encouragement of the production team....

  2. a-SiNx:H 薄膜的热丝化学气相沉积及微结构研究%Research of hot wire chemical vapor deposition and micro-structure of a-SiNx:H thin film

    Institute of Scientific and Technical Information of China (English)

    张娜; 周炳卿; 张林睿; 路晓翠

    2016-01-01

    In order to study the effect of hot wire temperature on the properties of a-SiNx:H thin films, by using hot wire chemical vapor deposition method and using SiH 4 , NH3 , H2 as reaction gas source , a-SiNx:H films were deposited by changing the temperature of hot wire .Film luminescent properties , microstructure and bonding characteristics were gotten and analyzed in detail by means of measurement methods such as ultraviolet-visible optical absorption spectroscopy , Fourier transform infrared transmission spectroscopy , and photoluminescence spectrum .The results show that , when wire temperature is at 1645℃, H content reaches greatest , N content is extremely small , film has high refractive index and a large degree of order .When the wire temperature is at 1713℃, H content decreases , N content reaches extremes .And then, with the increase of hot wire temperature, N content decreases and internal defect intensity increases .The results show that the best value of hot filament temperature is between 1596℃ to 1680℃ and the refractive index of film is 2.0.The film, with full nitrogen and hydrogen contents and stable structure and characteristics , is suit to choose as silicon-based solar cell antireflection film .%为了研究热丝温度对a-SiNx:H薄膜性能的影响,采用热丝化学气相沉积法,以SiH4,NH3,H2为反应气源,改变热丝温度沉积薄膜。通过紫外-可见光吸收谱、傅里叶红外透射光谱、光致发光光谱等测试手段对薄膜发光特性、微观结构及键合情况进行表征与分析。从测试情况可知,当热丝温度为1645℃时,H含量最大,N含量最小,同时其折射率最高,薄膜材料的有序度增大;当热丝温度为1713℃时,H含量减少,N含量达到最大,且随着热丝温度增大,薄膜中N含量又开始下降,内部缺陷态密度增加。结果表明,热丝法制备a-SiNx :H薄膜的热丝温度最佳值在1596℃~1680℃之间,此

  3. Thin Layer Modeling of the Convective Drying of Barberry Fruit (Berberis vulgaris

    Directory of Open Access Journals (Sweden)

    Akram Sharifi

    2013-04-01

    Full Text Available In this study, the drying kinetics of seedless barberry fruit was studied at 55, 65 and 75˚C air temperatures and 1±0.2 m/s air velocity in a laboratory thin layer dryer with forced convection. Samples were subjected to two different pretreatments (citric acid and vapor. The drying of seedless barberry fruit took place in the falling rate drying period. Ten thin layer-drying models were fitted to the experimental moisture ratio. Compared with other models the Midilli et al. (2002 drying model was found to satisfactorily describe the drying curves of barberry with highest amounts of coefficient of determination (r2 and lowest amounts of reduced chi-square(x2, Mean Bias Error (MBE and Root Mean Square Error (RMSE. The effective moisture diffusivity (Deff of barberry increased as the drying air temperature increased. An Arrhenius relation with activation energy values of 45.577 kJ/mol (citric acid pretreatment expressed the effect of temperature on the diffusivity.

  4. Hierarchical modeling and its numerical implementation for layered thin elastic structures

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Jin-Rae [Hongik University, Sejong (Korea, Republic of)

    2017-05-15

    Thin elastic structures such as beam- and plate-like structures and laminates are characterized by the small thickness, which lead to classical plate and laminate theories in which the displacement fields through the thickness are assumed linear or higher-order polynomials. These classical theories are either insufficient to represent the complex stress variation through the thickness or may encounter the accuracy-computational cost dilemma. In order to overcome the inherent problem of classical theories, the concept of hierarchical modeling has been emerged. In the hierarchical modeling, the hierarchical models with different model levels are selected and combined within a structure domain, in order to make the modeling error be distributed as uniformly as possible throughout the problem domain. The purpose of current study is to explore the potential of hierarchical modeling for the effective numerical analysis of layered structures such as laminated composite. For this goal, the hierarchical models are constructed and the hierarchical modeling is implemented by selectively adjusting the level of hierarchical models. As well, the major characteristics of hierarchical models are investigated through the numerical experiments.

  5. Small signal gain based on analytic models of thin intense electron beams

    Science.gov (United States)

    James Elliott, C.; McVey, Brian; Schmitt, Mark

    1991-07-01

    We develop the free electron laser theory of the effective energy distribution and the small signal gain for a thin electron beam. The assumption of thinness allows us to treat various transverse locations and electron beam trajectory angles as introducing phase shifts that have the same effect as those introduced by a change in energy of the electron. These ideas extend previous work of Colson et al., Dattoli et al., Scharlemann, and others in five important ways. The first is the ability to treat electron beams with three different classes of matching or symmetry conditions: (i) electron beams with separate betatron matching in each plane. (ii) those with aspect ratio matching, and (iii) crossed matched beams. Manifestations of these symmetries include elliptical cross-sections and electron beams that have modulated spatial profiles. For these we derive analytical expressions for effective energy distributions. Second, two emittance parameters for the electron beam are shown to consolidate into a single parameter that describes most of the energy variation of the effective energy distributions. Thus, the effective energy distribution for a 1:4 ribbon electron beam is nearly equivalent to a distribution for a beam of circular cross-section. Third, these calculations extend to energy distributions, angular distributions, and spatial distributions that all follow Gaussian profiles. Fourth, this model incorporates the description of the incident Gaussian optical beam and the above electron beam dynamics into a single influence function kernel. Emittance, energy spread, diffraction, and gain may be interpreted as limiting the length over which the bunching contributions of the propagating electric fields downstream are important. Fifth, three-dimensional profiles of the optical fields are computed. This work is complementary to the recent work of Yu, Krinsky and Gluckstern in that ours always describes the transition from low gain to high gain for a thin beam and not

  6. An interconnecting bus power optimization method combining interconnect wire spacing with wire ordering

    Institute of Scientific and Technical Information of China (English)

    Zhu Zhang-Ming; Hao Bao-Tian; En Yun-Fei; Yang Yin-Tang; Li Yue-Jin

    2011-01-01

    On-chip interconnect buses consume tens of percents of dynamic power in a nanometer scale integrated circuit and they will consume more power with the rapid scaling down of technology size and continuously rising clock frequency,therefore it is meaningful to lower the interconnecting bus power in design. In this paper, a simple yet accurate interconnect parasitic capacitance model is presented first and then, based on this model, a novel interconnecting bus optimization method is proposed. Wire spacing is a process for spacing wires for minimum dynamic power, while wire ordering is a process that searches for wire orders that maximally enhance it. The method, i.e., combining wire spacing with wire ordering, focuses on bus dynamic power optimization with a consideration of bus performance requirements.The optimization method is verified based on various nanometer technology parameters, showing that with 50% slack of routing space, 25.71% and 32.65% of power can be saved on average by the proposed optimization method for a globalbus and an intermediate bus, respectively, under a 65-nm technology node, compared with 21.78% and 27.68% of power saved on average by uniform spacing technology. The proposed method is especially suitable for computer-aided designof nanometer scale on-chip buses.

  7. A new analytical model of high voltage silicon on insulator (SOI) thin film devices

    Institute of Scientific and Technical Information of China (English)

    Hu Sheng-Dong; Zhang Bo; Li Zhao-Ji

    2009-01-01

    A new analytical model of high voltage silicon on insulator (SOI) thin film devices is proposed, and a formula of silicon critical electric field is derived as a function of silicon film thickness by solving a 2D Poisson equation from an effective ionization rate, with a threshold energy taken into account for electron multiplying. Unlike a conventional silicon critical electric field that is constant and independent of silicon film thickness, the proposed silicon critical electric field increases sharply with silicon film thickness decreasing especially in the case of thin films, and can come to 141 V/μm at a film thickness of 0.1 μm which is much larger than the normal value of about 30 V/μm. From the proposed formula of silicon critical electric field, the expressions of dielectric layer electric field and vertical breakdown voltage (VB,V) are obtained. Based on the model, an ultra thin film can be used to enhance dielectric layer electric field and so increase vertical breakdown voltage for SOI devices because of its high silicon critical electric field, and with a dielectric layer thickness of 2 μm the vertical breakdown voltages reach 852 and 300V for the silicon film thicknesses of 0.1 and 5μm, respectively. In addition, a relation between dielectric layer thickness and silicon film thickness is obtained, indicating a minimum vertical breakdown voltage that should be avoided when an SOI device is designed. 2D simulated results and some experimental results are in good agreement with analytical results.

  8. Necessary Conditions for Accurate, Transient Hot-Wire Measurements of the Apparent Thermal Conductivity of Nanofluids are Seldom Satisfied

    Science.gov (United States)

    Antoniadis, Konstantinos D.; Tertsinidou, Georgia J.; Assael, Marc J.; Wakeham, William A.

    2016-08-01

    The paper considers the conditions that are necessary to secure accurate measurement of the apparent thermal conductivity of two-phase systems comprising nanoscale particles of one material suspended in a fluid phase of a different material. It is shown that instruments operating according to the transient hot-wire technique can, indeed, produce excellent measurements when a finite element method (FEM) is employed to describe the instrument for the exact geometry of the hot wire. Furthermore, it is shown that an approximate analytic solution can be employed with equal success, over the time range of 0.1 s to 1 s, provided that (a) two wires are employed, so that end effects are canceled, (b) each wire is very thin, less than 30 \\upmu m diameter, so that the line source model and the corresponding corrections are valid, (c) low values of the temperature rise, less than 4 K, are employed in order to minimize the effect of convection on the heat transfer in the time of measurement of 1 s, and (d) insulated wires are employed for measurements in electrically conducting or polar liquids to avoid current leakage or other electrical distortions. According to these criteria, a transient hot-wire instrument has been designed, constructed, and employed for the measurement of the enhancement of the thermal conductivity of water when TiO2 or multi-wall carbon nanotubes (MWCNT) are added. These new results, together with a critical evaluation of other measurements, demonstrate the importance of proper implementation of the technique.

  9. Reduced model for precessional switching of thin-film nanomagnets under the influence of spin torque

    Science.gov (United States)

    Lund, Ross G.; Chaves-O'Flynn, Gabriel D.; Kent, Andrew D.; Muratov, Cyrill B.

    2016-10-01

    We study the magnetization dynamics of thin-film magnetic elements with in-plane magnetization subject to a spin current flowing perpendicular to the film plane. We derive a reduced partial differential equation for the in-plane magnetization angle in a weakly damped regime. We then apply this model to study the experimentally relevant problem of switching of an elliptical element when the spin polarization has a component perpendicular to the film plane, restricting the reduced model to a macrospin approximation. The macrospin ordinary differential equation is treated analytically as a weakly damped Hamiltonian system, and an orbit-averaging method is used to understand transitions in solution behaviors in terms of a discrete dynamical system. The predictions of our reduced model are compared to those of the full Landau-Lifshitz-Gilbert-Slonczewski equation for a macrospin.

  10. Geometrical nonlinear deformation model and its experimental study on bimorph giant magnetostrictive thin film

    Institute of Scientific and Technical Information of China (English)

    Wei LIU; Zhenyuan JIA; Fuji WANG; Yongshun ZHANG; Dongming GUO

    2008-01-01

    The geometrical nonlinearity of a giant magne-tostrictive thin film (GMF) can be clearly detected under the magnetostriction effect. Thus, using geometrical linear elastic theory to describe the strain, stress, and constitutive relationship of GMF is inaccurate. According to nonlinear elastic theory, a nonlinear deformation model of the bimorph GMF is established based on assumptions that the magnetostriction effect is equivalent to the effect of body force loaded on the GMF. With Taylor series method, the numerical solution is deduced. Experiments on TbDyFe/Polyimide (PI)/SmFe and TbDyFe/Cu/SmFe are then conducted to verify the proposed model, respectively. Results indicate that the nonlinear deflection curve model is in good conformity with the experimental data.

  11. Finite element modeling of power spinning of thin-walled shell with hoop inner rib

    Institute of Scientific and Technical Information of China (English)

    BAI Qian; YANG He; ZHAN Mei

    2008-01-01

    A 3D elasto-plastic finite element(FE) model of power spinning of thin-walled aluminum alloy shell with hoop inner rib was established under software ABAQUS. Key technologies were dealt with reasonably. The reliability of the FE model was verified theoretically and experimentally. The forming process was simulated and studied. The distribution of the thickness and stress, and the variations of spinning force were obtained. The workpiece springback was analyzed with ABAQUS/Standard. The results show that the FE model considering elastic deformation can not only be used to analyze the workpiece springback in the complex spinning process, but also serve as a significant guide to study the local deformation mechanism and choose the reasonable parameters.

  12. Note on the hydrodynamic description of thin nematic films: strong anchoring model

    CERN Document Server

    Lin, Te-Sheng; Archer, Andrew J; Kondic, Lou; Thiele, Uwe

    2013-01-01

    We discuss the long-wave hydrodynamic model for a thin film of nematic liquid crystal in the limit of strong anchoring at the free surface and at the substrate. Our aim is to clarify how the elastic energy enters the evolution equation for the film thickness; several models exist in the literature that result in qualitatively different behaviour. We consolidate the various approaches and show that the long-wave model derived through an asymptotic expansion of the full nemato-hydrodynamic equations with consistent boundary conditions agrees with the equation one obtains by employing a thermodynamically motivated gradient dynamics formulation based on an underlying free energy functional. As a result, we find that the elastic distortion energy is always stabilising in the case of strong anchoring. To support the discussion in the main part of the paper, an appendix gives the full derivation of the evolution equation for the film thickness via asymptotic expansion.

  13. Analytical model for release calculations in solid thin-foils ISOL targets

    Energy Technology Data Exchange (ETDEWEB)

    Egoriti, L. [Belgian Nuclear Research Centre (SCK-CEN), Boeretang 200, B-2400 Mol (Belgium); Politecnico di Milano, Department of Energy, CeSNEF-Nuclear Engineering Division, Via Ponzio, 34/3, 20133 Milano (Italy); Boeckx, S. [Belgian Nuclear Research Centre (SCK-CEN), Boeretang 200, B-2400 Mol (Belgium); ICTEAM Inst., Univ. Catholique de Louvain, Louvain-la-Neuve (Belgium); Ghys, L. [Belgian Nuclear Research Centre (SCK-CEN), Boeretang 200, B-2400 Mol (Belgium); Houngbo, D., E-mail: donald.houngbo@sckcen.be [Belgian Nuclear Research Centre (SCK-CEN), Boeretang 200, B-2400 Mol (Belgium); Department of Flow, Heat and Combustion Mechanics, Gent University (UGent), St.-Pietersnieuwstraat 41, B-9000 Gent (Belgium); Popescu, L. [Belgian Nuclear Research Centre (SCK-CEN), Boeretang 200, B-2400 Mol (Belgium)

    2016-10-01

    A detailed analytical model has been developed to simulate isotope-release curves from thin-foils ISOL targets. It involves the separate modeling of diffusion and effusion inside the target. The former has been modeled using both first and second Fick's law. The latter, effusion from the surface of the target material to the end of the ionizer, was simulated with the Monte Carlo code MolFlow+. The calculated delay-time distribution for this process was then fitted using a double-exponential function. The release curve obtained from the convolution of diffusion and effusion shows good agreement with experimental data from two different target geometries used at ISOLDE. Moreover, the experimental yields are well reproduced when combining the release fraction with calculated in-target production.

  14. Analytical model for release calculations in solid thin-foils ISOL targets

    Science.gov (United States)

    Egoriti, L.; Boeckx, S.; Ghys, L.; Houngbo, D.; Popescu, L.

    2016-10-01

    A detailed analytical model has been developed to simulate isotope-release curves from thin-foils ISOL targets. It involves the separate modeling of diffusion and effusion inside the target. The former has been modeled using both first and second Fick's law. The latter, effusion from the surface of the target material to the end of the ionizer, was simulated with the Monte Carlo code MolFlow+. The calculated delay-time distribution for this process was then fitted using a double-exponential function. The release curve obtained from the convolution of diffusion and effusion shows good agreement with experimental data from two different target geometries used at ISOLDE. Moreover, the experimental yields are well reproduced when combining the release fraction with calculated in-target production.

  15. Analytical model for release calculations in solid thin-foils ISOL targets

    CERN Document Server

    Egoriti, Luca; Ghys, Lars; Houngbo, Donald; Popescu, Lucia

    2016-01-01

    A detailed analytical model has been developed to simulate isotope-release curves from thin-foils ISOL targets. It involves the separate modelling of diffusion and effusion inside the target. The former has been modelled using both first and second Fick's law. The latter, effusion from the surface of the target material to the end of the ionizer, was simulated with the Monte Carlo code MolFlow+. The calculated delay-time distribution for this process was then fitted using a double-exponential function. The release curve obtained from the convolution of diffusion and effusion shows good agreement with experimental data from two different target geometries used at ISOLDE. Moreover, the experimental yields are well reproduced when combining the release fraction with calculated in-target production.

  16. Thin-Sheet Inversion Modeling of Geomagnetic Deep Sounding Data Using MCMC Algorithm

    Directory of Open Access Journals (Sweden)

    Hendra Grandis

    2013-01-01

    Full Text Available The geomagnetic deep sounding (GDS method is one of electromagnetic (EM methods in geophysics that allows the estimation of the subsurface electrical conductivity distribution. This paper presents the inversion modeling of GDS data employing Markov Chain Monte Carlo (MCMC algorithm to evaluate the marginal posterior probability of the model parameters. We used thin-sheet model to represent quasi-3D conductivity variations in the heterogeneous subsurface. The algorithm was applied to invert field GDS data from the zone covering an area that spans from eastern margin of the Bohemian Massif to the West Carpathians in Europe. Conductivity anomalies obtained from this study confirm the well-known large-scale tectonic setting of the area.

  17. Implementation of a Dynamic Mooring Solver (MOODY) into a wave to wire model of a simple WEC

    DEFF Research Database (Denmark)

    Ferri, Francesco; Palm, Johannes

    This report forms the deliverable D4.6 of the Structural Design of Wave Energy Devices (SDWED) project. The main objective of the report is to shed light on the implementation of a simple floating wave energy converter (fWEC) numerical model coupled with a dynamic model of the reaction system. Th...

  18. Models for the optical simulations of fractal aggregated soot particles thinly coated with non-absorbing aerosols

    Science.gov (United States)

    Wu, Yu; Cheng, Tianhai; Zheng, Lijuan; Chen, Hao

    2016-10-01

    Light absorption enhancement of aged soot aerosols is highly sensitive to the morphologies and mixing states of soot aggregates and their non-absorbing coatings, such as organic materials. The quantification of these effects on the optical properties of thinly coated soot aerosols is simulated using an effective model with fixed volume fractions. Fractal aggregated soot was simulated using the diffusion limited aggregation (DLA) algorithm and discretized into soot dipoles. The dipoles of non-absorbing aerosols, whose number was fixed by the volume fraction, were further generated from the neighboring random edge dipoles. Their optical properties were calculated using the discrete dipole approximation (DDA) method and were compared with other commonly used models. The optical properties of thinly coated soot calculated using the fixed volume fraction model are close to (less than ~10% difference) the results of the fixed coating thickness model, except their asymmetry parameters (up to ~25% difference). In the optical simulations of thinly coated soot aerosols, this relative difference of asymmetry parameters and phase functions between these realistic models may be notable. The realizations of the fixed volume fraction model may introduce smaller variation of optical results than those of the fixed coating thickness model. Moreover, the core-shell monomers model and homogeneous aggregated spheres model with the Maxwell-Garnett (MG) theory may underestimate (up to ~20%) the cross sections of thinly coated soot aggregates. The single core-shell sphere model may largely overestimate (up to ~150%) the cross sections and single scattering albedo of thinly coated soot aggregates, and it underestimated (up to ~60%) their asymmetry parameters. It is suggested that the widely used single core-shell sphere approximation may not be suitable for the single scattering calculations of thinly coated soot aerosols.

  19. Dynamics of a spreading thin film with gravitational counterflow using slip model

    Indian Academy of Sciences (India)

    Naveen Tiwari

    2015-05-01

    Thin liquid films can be made to spread along a solid surface by application of temperature gradients at the liquid–gas interface. The surface tension of usual liquids decreases linearly with temperature thus producing the driving thermocapillary stresses due to the applied temperature gradient. These spreading films are susceptible to a fingering instability at the advancing solid–liquid–vapor contact line, which is linked to the development of a capillary ridge near the advancing front. A thin film climbing up on a vertical substrate against gravity shows interesting dynamics due to strong opposing gravitational counterflow. At the contact-line of the spreading film, slip-model is used to alleviate the stress-singularity due to more usual no-slip boundary condition. It is shown that depending upon the magnitude of a gravitational drainage parameter the steady-profiles of the spreading films show qualitatively different dynamics. The dynamics is in agreement with the experimentally observed profiles in the literature as well as computed profiles using precursor-film model at the contact-line in some earlier theoretical studies. Briefly, their stability behavior is also discussed.

  20. The impact of thin models in music videos on adolescent girls' body dissatisfaction.

    Science.gov (United States)

    Bell, Beth T; Lawton, Rebecca; Dittmar, Helga

    2007-06-01

    Music videos are a particularly influential, new form of mass media for adolescents, which include the depiction of scantily clad female models whose bodies epitomise the ultra-thin sociocultural ideal for young women. The present study is the first exposure experiment that examines the impact of thin models in music videos on the body dissatisfaction of 16-19-year-old adolescent girls (n=87). First, participants completed measures of positive and negative affect, body image, and self-esteem. Under the guise of a memory experiment, they then either watched three music videos, listened to three songs (from the videos), or learned a list of words. Affect and body image were assessed afterwards. In contrast to the music listening and word-learning conditions, girls who watched the music videos reported significantly elevated scores on an adaptation of the Body Image States Scale after exposure, indicating increased body dissatisfaction. Self-esteem was not found to be a significant moderator of this relationship. Implications and future research are discussed.

  1. Constitutive model based on dislocation density and ductile fracture of monel 400 thin sheet under tension

    Science.gov (United States)

    Wang, Chuanjie; Xue, Shaoxi; Chen, Gang; Zhang, Peng

    2017-02-01

    In micro-scaled plastic deformation, material strength and ductile fracture behaviors of thin sheet in tension are quite different from those in macro-scale. In this study, uniaxial tensile tests of Monel 400 thin sheets with different microstructures were carried out to investigate the plastic deformation size effect in micro-scale. The experimental results indicate that the flow stress and fracture strain departure from the traditional empirical formula when there are only fewer grains across the thickness. And the number of dimples on the fracture surface is getting smaller with the decreasing ratio of specimen thickness to grain size. Then, a constitutive model based on dislocation density considering the free surface effect in micro-scale is proposed to reveal the mechanism of the flow stress size effect. In addition, a model is proposed considering the surface roughening inducing the thickness nonuniform and the decrease of micro-voids resulting from the reduction of grain boundary density with the decreasing ratio of specimen thickness to grain size. The interactive effects of the surface roughening and the decrease of micro-voids result in the earlier fracture in micro tension of the specimen with fewer grains across the thickness.

  2. Understanding geometric instabilities in thin films via a multi-layer model.

    Science.gov (United States)

    Lejeune, Emma; Javili, Ali; Linder, Christian

    2016-01-21

    When a thin stiff film adhered to a compliant substrate is subject to compressive stresses, the film will experience a geometric instability and buckle out of plane. For high film/substrate stiffness ratios with relatively low levels of strain, the primary mode of instability will either be wrinkling or buckling delamination depending on the material and geometric properties of the system. Previous works approach these systems by treating the film and substrate as homogenous layers, either consistently perfectly attached, or perfectly unattached at interfacial flaws. However, this approach neglects systems where the film and substrate are uniformly weakly attached or where interfacial layers due to surface modifications in either the film or substrate are present. Here we demonstrate a method for accounting for these additional thin surface layers via an analytical solution verified by numerical results. The main outcome of this work is an improved understanding of how these layers influence global behavior. We demonstrate the utility of our model with applications ranging from buckling based metrology in ultrathin films, to an improved understanding of the formation of a novel surface in carbon nanotube bio-interface films. Moving forward, this model can be used to interpret experimental results, particularly for systems which deviate from traditional behavior, and aid in the evaluation and design of future film/substrate systems.

  3. Induced voltage in an open wire

    CERN Document Server

    Morawetz, K; Trupp, A

    2015-01-01

    A puzzle arising from Faraday's law is considered and solved concerning the question which voltage is induced in an open wire feeling a time-varying homogeneous magnetic field. The longitudinal electric field contributes 1/3 and the transverse field 2/3 to the induced voltage. The representation of a homogeneous and time-varying magnetic field implies unavoidably a certain symmetry point or line dependent on the geometry of the source. As a consequence the induced voltage of an open wire is found to be the area covered with respect to the symmetry line or point perpendicular to the magnetic field. This in turn allows to find the symmetry points of a magnetic field source by measuring the voltage of an open wire. We present two exactly solvable models for a symmetry point and for a symmetry line. The results are applicable to open circuit problems and for astrophysical applications.

  4. Nanosecond electrical explosion of bare and dielectric coated tungsten wire in vacuum

    Science.gov (United States)

    Wang, Kun

    2017-02-01

    Experiments of the electrical explosion of tungsten wire with and without insulating coatings demonstrate that the insulating coatings exert a significant influence on the exploding characteristics. The shadowgraphy and interferometry diagnostics are applied to present the morphology of the exploding products. In the experiments, energy of ˜3.2 eV/atom is deposited into the bare tungsten wire at the instant of voltage breakdown, giving a velocity of 0.38 km/s for the high density core. The value and structure of the energy deposition for the tungsten wire explosions are substantially improved by employing the thin dielectric coatings. Energy of ˜15.2 eV/atom is deposited into the coated tungsten wire transforming the wire into gaseous state and the expanding velocity of the high density core is 5.64 km/s. The interference phase shift and atomic density are reconstructed from the interferogram for the exploding coated tungsten wire.

  5. From a thin film model for passive suspensions towards the description of osmotic biofilm spreading

    CERN Document Server

    Trinschek, Sarah; Thiele, Uwe

    2016-01-01

    Biofilms are ubiquitous macro-colonies of bacteria that develop at various interfaces (solid-liquid, solid-gas or liquid-gas). The formation of biofilms starts with the attachment of individual bacteria to an interface, where they proliferate and produce a slimy polymeric matrix - two processes that result in colony growth and spreading. Recent experiments on the growth of biofilms on agar substrates under air have shown that for certain bacterial strains, the production of the extracellular matrix and the resulting osmotic influx of nutrient-rich water from the agar into the biofilm are more crucial for the spreading behaviour of a biofilm than the motility of individual bacteria. We present a model which describes the biofilm evolution and the advancing biofilm edge for this spreading mechanism. The model is based on a gradient dynamics formulation for thin films of biologically passive liquid mixtures and suspensions, supplemented by bioactive processes which play a decisive role in the osmotic spreading o...

  6. Modeling chiral sculptured thin films as platforms for surface-plasmonic-polaritonic optical sensing

    CERN Document Server

    Mackay, Tom G

    2010-01-01

    Biomimetic nanoengineered metamaterials called chiral sculptured thin films (CSTFs) are attractive platforms for optical sensing because their porosity, morphology and optical properties can be tailored to order. Furthermore, their ability to support more than one surface-plasmon-polariton (SPP) wave at a planar interface with a metal offers functionality beyond that associated with conventional SPP--based sensors. An empirical model was constructed to describe SPP-wave propagation guided by the planar interface of a CSTF--infiltrated with a fluid which supposedly contains analytes to be detected--and a metal. The inverse Bruggeman homogenization formalism was first used to determine the nanoscale model parameters of the CSTF. These parameters then served as inputs to the forward Bruggeman homogenization formalism to determine the reference relative permittivity dyadic of the infiltrated CSTF. By solving the coresponding boundary-value problem for a modified Kretschmann configuration, the characteristics of t...

  7. Theoretical model for thin ferroelectric films and the multilayer structures based on them

    Energy Technology Data Exchange (ETDEWEB)

    Starkov, A. S., E-mail: starkov@iue.tuwien.ac.at; Pakhomov, O. V. [St. Petersburg National Research Univeristy ITMO, Institute of Refrigeration and Biotechnologies (Russian Federation); Starkov, I. A. [Vienna University of Technology, Institute for Microelectronics (Austria)

    2013-06-15

    A modified Weiss mean-field theory is used to study the dependence of the properties of a thin ferroelectric film on its thickness. The possibility of introducing gradient terms into the thermodynamic potential is analyzed using the calculus of variations. An integral equation is introduced to generalize the well-known Langevin equation to the case of the boundaries of a ferroelectric. An analysis of this equation leads to the existence of a transition layer at the interface between ferroelectrics or a ferroelectric and a dielectric. The permittivity of this layer is shown to depend on the electric field direction even if the ferroelectrics in contact are homogeneous. The results obtained in terms of the Weiss model are compared with the results of the models based on the correlation effect and the presence of a dielectric layer at the boundary of a ferroelectric and with experimental data.

  8. Crustal thinning between the Ethiopian and East African Plateaus from modeling Rayleigh wave dispersion

    Energy Technology Data Exchange (ETDEWEB)

    Benoit, M H; Nyblade, A A; Pasyanos, M E

    2006-01-17

    The East African and Ethiopian Plateaus have long been recognized to be part of a much larger topographic anomaly on the African Plate called the African Superswell. One of the few places within the African Superswell that exhibit elevations of less than 1 km is southeastern Sudan and northern Kenya, an area containing both Mesozoic and Cenozoic rift basins. Crustal structure and uppermost mantle velocities are investigated in this area by modeling Rayleigh wave dispersion. Modeling results indicate an average crustal thickness of 25 {+-} 5 km, some 10-15 km thinner than the crust beneath the adjacent East African and Ethiopian Plateaus. The low elevations can therefore be readily attributed to an isostatic response from crustal thinning. Low Sn velocities of 4.1-4.3 km/s also characterize this region.

  9. Micropolar interface model of thin-layered interconnection components with heterogeneous internal microstructures

    Institute of Scientific and Technical Information of China (English)

    ZHANG; Yan; FAN; Jing-yu

    2009-01-01

    Being a wide variety of thin-layered interconnection components in electronics packaging with relatively small scale and heterogeneous materials, conventional numerical methods may be time consuming and even inefficacious to obtain an accurate prediction for the interface behavior under mechanical and/or thermal loading. Rather than resort to a fully spatial discretization in the vicinity of this interface zone, an interface model was proposed within the framework of micropolar theory by introducing discontinuous approximation. A fracture description was used to represent the microscopic failure progress inside the interface. The micropolar interface model was then numerically implemented with the finite element method. As an application, the interface behavior of a packaging system with anisotropic conductive adhesive(ACA)joint was analyzed, demonstrating its applicability and great efficiency.

  10. Experimental hysteretic loss for a series of superconducting filamentary NbTi wires and a field dependent critical state model. Final technical report 2 Oct 1972--31 Dec 1974

    Energy Technology Data Exchange (ETDEWEB)

    Ohmer, M.C.; Wollan, J.J.; Lawson, L.O.

    1975-07-01

    This report summarizes the Air Force superconducting wire applications, the goals of future superconducting materials development, the state of the art theories of ac loss in superconductors, and the results of hysteretic loss measurements on a series of niobium--titanium multifilamentary wires. Expressions were developed for magnetization and hysteretic loss for half cycle and full cycle for rod geometries for a critical state model with critical current inversely proportional to field. Bulk effects with surface like character are discussed along with surface shielding fields and the demagnetizing factor. The loss expressions of various models are compared to experimental loss. Universal loss curves constructed from experimental loss curves by appropriate normalization are obtained and used to predict loss accurately. (GRA)

  11. Wired to freedom

    DEFF Research Database (Denmark)

    Jepsen, Kim Sune Karrasch; Bertilsson, Margareta

    2017-01-01

    of cochlear implantations among Danish users in order to shed more light on their social and political implications. We situate cochlear implantation in a framework of new life science advances, politics, and user experiences. Analytically, we draw upon the notion of social imaginary and explore the social...... dimension of life science through a notion of public politics adopted from the political theory of John Dewey. We show how cochlear implantation engages different social imaginaries on the collective and individual levels and we suggest that users share an imaginary of being “wired to freedom” that involves...... new access to social life, continuous communicative challenges, common practices, and experiences. In looking at their lives as “wired to freedom,” we hope to promote a wider spectrum of civic participation in the benefit of future life science developments within and beyond the field of Cochlear...

  12. From Wires to Cosmology

    CERN Document Server

    Amin, Mustafa A

    2015-01-01

    We provide a statistical framework for characterizing stochastic particle production in the early universe via a precise correspondence to current conduction in wires with impurities. Our approach is particularly useful when the microphysics is uncertain and the dynamics are complex, but only coarse-grained information is of interest. We study scenarios with multiple interacting fields and derive the evolution of the particle occupation numbers from a Fokker-Planck equation. At late times, the typical occupation numbers grow exponentially which is the analog of Anderson localization for disordered wires. Some statistical features of the occupation numbers show hints of universality in the limit of a large number of interactions and/or a large number of fields. For test cases, excellent agreement is found between our analytic results and numerical simulations.

  13. Standard surface grinder for precision machining of thin-wall tubing

    Science.gov (United States)

    Jones, A.; Kotora, J., Jr.; Rein, J.; Smith, S. V.; Strack, D.; Stuckey, D.

    1967-01-01

    Standard surface grinder performs precision machining of thin-wall stainless steel tubing by electrical discharge grinding. A related adaptation, a traveling wire electrode fixture, is used for machining slots in thin-walled tubing.

  14. Twisting wire scanner

    CERN Document Server

    Gharibyan, V; Krouptchenkov, I; Nölle, D; Tiessen, H; Werner, M; Wittenburg, K

    2012-01-01

    A new type of 'two-in-one' wire scanner is proposed. Recent advances in linear motors' technology make it possible to combine translational and rotational movements. This will allow to scan the beam in two perpendicular directions using a single driving motor and a special fork attached to it. Vertical or horizontal mounting will help to escape problems associated with the 45 deg scanners. Test results of the translational part with linear motors is presented.

  15. Modelling and experimental validation of thin layer indirect solar drying of mango slices

    Energy Technology Data Exchange (ETDEWEB)

    Dissa, A.O.; Bathiebo, J.; Kam, S.; Koulidiati, J. [Laboratoire de Physique et de Chimie de l' Environnement (LPCE), Unite de Formation et de Recherche en Sciences Exactes et Appliquee (UFR/SEA), Universite de Ouagadougou, Avenue Charles de Gaulle, BP 7021 Kadiogo (Burkina Faso); Savadogo, P.W. [Laboratoire Sol Eau Plante, Institut de l' Environnement et de Recherches Agricoles, 01 BP 476, Ouagadougou (Burkina Faso); Desmorieux, H. [Laboratoire d' Automatisme et de Genie des Procedes (LAGEP), UCBL1-CNRS UMR 5007-CPE Lyon, Bat.308G, 43 bd du 11 Nov. 1918 Villeurbanne, Universite Claude Bernard Lyon1, Lyon (France)

    2009-04-15

    The thin layer solar drying of mango slices of 8 mm thick was simulated and experimented using a solar dryer designed and constructed in laboratory. Under meteorological conditions of harvest period of mangoes, the results showed that 3 'typical days' of drying were necessary to reach the range of preservation water contents. During these 3 days of solar drying, 50%, 40% and 5% of unbound water were eliminated, respectively, at the first, second and the third day. The final water content obtained was about 16 {+-} 1.33% d.b. (13.79% w.b.). This final water content and the corresponding water activity (0.6 {+-} 0.02) were in accordance with previous work. The drying rates with correction for shrinkage and the critical water content were experimentally determined. The critical water content was close to 70% of the initial water content and the drying rates were reduced almost at 6% of their maximum value at night. The thin layer drying model made it possible to simulate suitably the solar drying kinetics of mango slices with a correlation coefficient of r{sup 2} = 0.990. This study thus contributed to the setting of solar drying time of mango and to the establishment of solar drying rates' curves of this fruit. (author)

  16. Modelling the effect of the radiation reaction force on the acceleration of ultra-thin foils

    Science.gov (United States)

    Duff, M. J.; Capdessus, R.; King, M.; Del Sorbo, D.; Ridgers, C. P.; McKenna, P.

    2017-05-01

    An investigation of the effects of the radiation reaction force on radiation pressure acceleration is presented. Through 1D(3V) PIC code simulations, it is found that radiation reaction causes a decrease in the target velocity during the interaction of an ultra-intense laser pulse with a solid density thin foil of varying thickness. This change in the target velocity can be related to the loss of backwards-directed electrons due to cooling and reflection in the laser field. The loss of this electron population changes the distribution of the emitted synchrotron radiation. We demonstrate that it is the emission of radiation which leads to the observed decrease in target velocity. Through a modification to the light sail equation of motion (which is used to describe radiation pressure acceleration in thin foils), which accounts for the conversion of laser energy to synchrotron radiation, we can describe this change in target velocity. This model can be tested in future experiments with ultra-high intensity lasers, and will lead to a better understanding of the process of relativistically induced transparency in the new intensity regime.

  17. Dual wire welding torch and method

    Science.gov (United States)

    Diez, Fernando Martinez; Stump, Kevin S.; Ludewig, Howard W.; Kilty, Alan L.; Robinson, Matthew M.; Egland, Keith M.

    2009-04-28

    A welding torch includes a nozzle with a first welding wire guide configured to orient a first welding wire in a first welding wire orientation, and a second welding wire guide configured to orient a second welding wire in a second welding wire orientation that is non-coplanar and divergent with respect to the first welding wire orientation. A method of welding includes moving a welding torch with respect to a workpiece joint to be welded. During moving the welding torch, a first welding wire is fed through a first welding wire guide defining a first welding wire orientation and a second welding wire is fed through a second welding wire guide defining a second welding wire orientation that is divergent and non-coplanar with respect to the first welding wire orientation.

  18. The Dielectric Breakdown Model applied to explain various morphologies of deposited metallic structures in thin gap metal electro-deposition

    Directory of Open Access Journals (Sweden)

    Aditya Chowdhury

    2015-06-01

    Full Text Available The phenomenon of metal electro-deposition in thin-gap geometry leads to very interesting and diverse two dimensional morphologies. This varies from dense ramified growth to thin dendritic projections. In this paper, we have proposed a stochastic model that incorporates such diversity. We carried out thin-gap electro-deposition of Copper and Zinc with varying electrolytic concentrations. A well known model, that until this work was used to explain dielectric breakdown patterns, was employed to explain the variation in deposition morphology with concentration. The sole parameter in the model was varied and the numerically obtained patterns was seen to correlate well with those obtained from electro-deposition. A linear relationship between the parameter and molar concentration was established. The established relationship was then analysed and interpreted.

  19. rf excited optical emission spectrum of radicals generated during hot wire chemical vapour deposition for the preparation of microcrystalline silicon thin film%射频激发热丝化学气相沉积制备硅薄膜过程中光发射谱的研究

    Institute of Scientific and Technical Information of China (English)

    李天微; 刘丰珍; 朱美芳

    2011-01-01

    To study the radicals behavior in the hot wire chemical vapour deposition (HWCVD) process for the preparation of microcrystalline Si (μc-Si: H) thin film, a weak radio frequency (rf) power was introduced to excite the radicals generated in HWCVD chamber. The spectrum of fi-excited HWCVD (rf-HWCVD) was obtained by subtracting the emission of hot wires from the spectrum measured by OES. The influence of the rf power on the rf-HWCVD spectrum can be neglected as the rf power density was less than 0. 1 W/cm2. Under the same deposition parameters, the emission spectra for rf-HWCVD and plasma enhanced CVD (PECVD) processes are different. Under the low deposition pressure ( 7.5 Pa), the intensities of Sill * and Hα vary with the hot wire temperature reversely, which is characteristic of HWCVD with high gas dissociation rate and high concentration of atomic H. The ratio of intensity of Hα to Sill * in the emission spectrum of rf-HWCVD varying with deposition pressure is consistent with the crystalline fraction of μc-Si: H film. The results indicate that the optical emission spectroscopy measurement is a suitable method for the investigation of the HWCVD process excited by a weak rf-power.%采用射频(rf)激发,在热丝化学气相沉积(HWCVD)制备微晶硅薄膜的过程中产生发光基元,测量了rf激发HWCVD(rf-HWCVD)的光发射谱,比较了相同工艺条件下rf-HWCVD和等离子体增强CVD(PECVD)的光发射谱,分析了rf功率、热丝温度和沉积气压对rf-HWCVD光发射谱的影响.结果表明,在射频功率<0.1W/cm1时,rf-HWCVD发射光谱反映了HWCVD高的气体分解效率和高浓度原子氢的特点,能够解释气压变化与微晶硅薄膜微结构的关系,是研究HWCVD气相过程的有效方法之一.

  20. Ablation dynamics in wire array Z-pinches under modifications on global magnetic field topology

    Energy Technology Data Exchange (ETDEWEB)

    Veloso, Felipe, E-mail: fveloso@fis.puc.cl; Muñoz-Cordovez, Gonzalo; Donoso-Tapia, Luis; Valenzuela-Villaseca, Vicente; Favre, Mario; Wyndham, Edmund [Instituto de Física, Pontificia Universidad Católica de Chile, Av Vicuña Mackenna 4860, Macul, Santiago (Chile); Suzuki-Vidal, Francisco; Swadling, George; Chittenden, Jeremy [Blackett Laboratory, Imperial College, London SW7 2BW (United Kingdom)

    2015-07-15

    The dynamics of ablation streams and precursor plasma in cylindrical wire array Z-pinches under temporal variations of the global magnetic field topology is investigated through experiments and numerical simulations. The wire arrays in these experiments are modified by replacing a pair of consecutive wires with wires of a larger diameter. This modification leads to two separate effects, both of which impact the dynamics of the precursor plasma; firstly, current is unevenly distributed between the wires and secondly, the thicker wires take longer to fully ablate. The uneven distribution of current is evidenced in the experiments by the drift of the precursor off axis due to a variation in the global magnetic field topology which modifies the direction of the ablation streams tracking the precursor position. The variation of the global magnetic field due to the presence of thick wires is studied with three-dimensional magnetohydrodynamic (MHD) simulations, showing that the global field changes from the expected toroidal field to a temporally variable topology after breakages appear in the thin wires. This leads to an observed acceleration of the precursor column towards the region closer to the thick wires and later, when thick wires also present breakages, it continues moving away from the original array position as a complicated and disperse object subject to MHD instabilities.