Nonlinear Vibroimpact Characteristics of a Planetary Gear Transmission System
Directory of Open Access Journals (Sweden)
Jianxing Zhou
2016-01-01
Full Text Available In order to research the vibroimpact characteristics of a planetary gear transmission system under high speed and lightly loaded conditions, a new modeling method is proposed. In the modeling process, linear spring was used to simulate gear mesh elasticity under heavy load cases, and Hertz contact theory was used to calculate the contact force of gear pair under light load cases. Then, effects of the working conditions on the system vibroimpact characteristics are analyzed. The results show that, with input speed growing, the mesh force produced obvious fluctuations on the resonance frequencies of the sun gear and carrier torsion vibration, ring gear’s transverse vibration under the heavy load. Under light load condition, the collision vibration occurs in the gear pair; the changing trend of the contact force shows strongly nonlinear characteristics. The time of mesh-apart in gears pair decreases gradually as the load is increased; until it reaches collision vibration threshold value, the gear pair is no longer mesh-apart. With increasing of the input speed, the time of mesh-apart is decreased gradually; the fluctuation amplitude of contact force shows a linearly increasing trend. The study provides useful theoretical guideline for planetary gear transmission low-noise design.
Nonlinear magnetoinductive transmission lines
Lazarides, Nikos; Tsironis, G P
2011-01-01
Power transmission in one-dimensional nonlinear magnetic metamaterials driven at one end is investigated numerically and analytically in a wide frequency range. The nonlinear magnetic metamaterials are composed of varactor-loaded split-ring resonators which are coupled magnetically through their mutual inductances, forming thus a magnetoiductive transmission line. In the linear limit, significant power transmission along the array only appears for frequencies inside the linear magnetoinductive wave band. We present analytical, closed form solutions for the magnetoinductive waves transmitting the power in this regime, and their discrete frequency dispersion. When nonlinearity is important, more frequency bands with significant power transmission along the array may appear. In the equivalent circuit picture, the nonlinear magnetoiductive transmission line driven at one end by a relatively weak electromotive force, can be modeled by coupled resistive-inductive-capacitive (RLC) circuits with voltage-dependent cap...
Johnson, J. M.; Reale, D. V.; Krile, J. T.; Garcia, R. S.; Cravey, W. H.; Neuber, A. A.; Dickens, J. C.; Mankowski, J. J.
2016-05-01
In this paper, a solid-state four element array gyromagnetic nonlinear transmission line high power microwave system is presented as well as a detailed description of its subsystems and general output capabilities. This frequency agile S-band source is easily adjusted from 2-4 GHz by way of a DC driven biasing magnetic field and is capable of generating electric fields of 7.8 kV/m at 10 m correlating to 4.2 MW of RF power with pulse repetition frequencies up to 1 kHz. Beam steering of the array at angles of ±16.7° is also demonstrated, and the associated general radiation pattern is detailed.
Nonlinear transmission sputtering
Bitensky, I. S.; Sigmund, P.
1996-05-01
General expressions have been derived for the nonlinear yield of transmission sputtering for an incident polyatomic ion under the assumption that the molecule breaks up on entering the target and that sputter yields are enhanced due to proximity of atomic trajectories. Special attention is given to the case of negligible Coulomb explosion where projectile atoms penetrate independently. For weakly overlapping trajectories, the yield enhancement factor of a polyatomic molecule can be expressed by that of a diatom, amended with a correction for triple correlations if necessary. This expression is in good agreement with recent experimental findings on phenylalanine targets. Pertinent results on multiple scattering of atomic ions are reviewed and applied to independently-moving fragment atoms. The merits of measurements at variable layer thickness in addition to variable projectile energy are mentioned.
剪式齿轮传动机构非线性动力学特性研究%Nonlinear dynamic characteristics of a scissor gear transmission system
Institute of Scientific and Technical Information of China (English)
何文运; 张俊红; 马梁
2015-01-01
考虑齿侧间隙、时变啮合刚度和摩擦力等因素，建立7自由度剪式齿轮传动系统非线性动力学模型，采用Runge-Kutta 法对转速、啮合齿隙、扭簧刚度、预紧力矩等对系统振动特性的影响进行了研究。结果表明，随着转速的升高系统逐渐进入混沌状态，中等转速区间系统的非线性动力学行为对转速的变化更为敏感；随着齿侧间隙的增大，混沌区间增大，混沌特性加强；扭簧刚度影响系统的非线性运动状态，但对冲击现象的影响较小，较小的扭簧刚度更有利于消除冲击现象；扭簧的预紧力矩影响系统啮合状态，最小预紧力矩的大小受负载力矩的影响且近似呈正比例关系。%Considering backlash of gear pairs,time-varying mesh stiffness and friction,a nonlinear dynamic model of a scissor gear transmission system with 7-DOF was established with the analytical mechanics theory.An example of such a system was used to investigate the effects of rotational speed,backlash,stiffness and preload of torsional spring on the nonlinear dynamic behavior of the system with Runge-Kutta method.The results showed that the system enters a chaotic state with increase in rotating speed,the nonlinear dynamic behavior of the system in the medium rotating speed range is more sensitive to the change of rotating speed;the larger the backlash,the bigger the rotating speed interval of chaos,the stronger the chaotic characteristics;the torsional stiffness of spring has an effect on the non-linear dynamic behavior of the system,but it has a smaller effect on the impact phenomenon,the smaller torsional stiffness is more helpful to avoiding separating and impacting states of the gear pair;preload of torsional spring affects meshing states of the system,the minimum preload torque is almost proportional to the effect of the load torque.
Transmission characteristics of BSE transponder
Yamamoto, M.; Fukuchi, H.; Kozu, T.; Igarashi, M.; Takeuchi, M.
1986-01-01
The transmission characteristics of the BSE transponder and their variation with the passage of time measured during the period from the beginning of BSE operation, May 1978 to March 1979, were previously reported. In this paper, the subsequent investigation completed by the time of the failure of the last high power amplifier of 100 watts of the BSE, June 1980, is discussed.
Nonlinear optical properties of induced transmission filters.
Owens, Daniel T; Fuentes-Hernandez, Canek; Hales, Joel M; Perry, Joseph W; Kippelen, Bernard
2010-08-30
The nonlinear optical (NLO) properties of induced transmission filters (ITFs) based on Ag are experimentally determined using white light continuum pump-probe measurements. The experimental results are supported using simulations based on the matrix transfer method. The magnitude of the NLO response is shown to be 30 times that of an isolated Ag film of comparable thickness. The impacts of design variations on the linear and NLO response are simulated. It is shown that the design can be modified to enhance the NLO response of an ITF by a factor of 2 or more over a perfectly matched ITF structure.
Thermal Rectification in Graded Nonlinear Transmission Lines
Institute of Scientific and Technical Information of China (English)
许文; 陈伟中; 陶锋
2011-01-01
We consider heat conduction in a nonlinear inductance-capacitance(LC)transmission line with an inductance gradient by adding white-noise signals.It is found that the heat flux in the direction of inductance decrease is larger than that in the direction of inductance increase.When the low-inductance end is at higher temperature,the phonon density decreases due to conversion to high-frequency phonons,which can not move to the high-inductance end due to its lower cutoff frequency.However,when the high-inductance end is at higher temperature,the loss of phonon density can be compensated for because some high-frequency phonons can move to the low-inductance end dur to its higher cutoff frequency.This leads to the asymmetry of energy transfer.Discussion shows that this asymmetry exists in a particular range of temperatures,and increases with the increase of the difference between heat baths and the inductance gradient.%We consider heat conduction in a nonlinear inductance-capacitance (LC) transmission line with an inductance gradient by adding white-noise signals. It is found that the heat flux in the direction of inductance decrease is larger than that in the direction of inductance increase. When the low-inductance end is at higher temperature, the phonon density decreases due to conversion to high-frequency phonons, which can not move to the high-inductance end due to its lower cutoff frequency. However, when the high-inductance end is at higher temperature, the loss of phonon density can be compensated for because some high-frequency phonons can move to the low-inductance end dur to its higher cutoff frequency. This leads to the asymmetry of energy transfer. Discussion shows that this asymmetry exists in a particular range of temperatures, and increases with the increase of the difference between heat baths and the inductance gradient.
Nonlinear I-V characteristics of nanoparticle compacts and nanocomposites
Energy Technology Data Exchange (ETDEWEB)
Herth, Simone [Rensselaer Polytechnic Institute, Troy, NY (United States); Bielefeld University, Bielefeld (Germany); Wang, Xiaoping; Hugener, Teresa; Schadler, Linda; Siegel, Richard [Rensselaer Polytechnic Institute, Troy, NY (United States); Hillborg, Henrik; Auletta, Tommaso [ABB AB, Corporate Research, Schweden (Sweden)
2007-07-01
Materials with nonlinear I-V characteristics are commonly used as field grading materials. In many cases, the non-linearity is achieved through the addition of equiaxed fillers to a polymer matrix. These composite field grading materials are optimized in terms of nonlinearity, conductivity, and breakdown strength. One limitation in designing new field grading materials is a robust understanding of the relationship between powder morphology, composition and electrical characteristics of the powder, as well as a robust understanding of the relationship between powder conductivity and non-linearity and composite non-linearity. In this work, treatment of ZnO powder with a SnF{sub 2} solution resulted in a powder that yielded highly non-linear behavior. The highest non-linearity was achieved for powders with at least two different phases and a rough surface, as indicated by transmission electron micrographs. In contrast, the non-linearity of the nanocomposite conductivity is mainly determined by the conductivity of the nanofiller. The electrical behavior of the non-linear powder can be understood by a polarization of the nanoparticles at the interfaces, whereas the nonlinearity of the nanocomposites can be explained by a tunnelling mechanism between two particles.
Nonlinear system guidance in the presence of transmission zero dynamics
Meyer, G.; Hunt, L. R.; Su, R.
1995-01-01
An iterative procedure is proposed for computing the commanded state trajectories and controls that guide a possibly multiaxis, time-varying, nonlinear system with transmission zero dynamics through a given arbitrary sequence of control points. The procedure is initialized by the system inverse with the transmission zero effects nulled out. Then the 'steady state' solution of the perturbation model with the transmission zero dynamics intact is computed and used to correct the initial zero-free solution. Both time domain and frequency domain methods are presented for computing the steady state solutions of the possibly nonminimum phase transmission zero dynamics. The procedure is illustrated by means of linear and nonlinear examples.
Optimal Transmission Power in a Nonlinear VLC System
Institute of Scientific and Technical Information of China (English)
ZHAO Shuang; CAI Sunzeng; KANG Kai; QIAN Hua
2016-01-01
In a visible light communication (VLC) system, the light emitting diode (LED) is nonlinear for large signals, which limits the trans⁃mission power or equivalently the coverage of the VLC system. When the input signal amplitude is large, the nonlinear distortion creates harmonic and intermodulation distortion, which degrades the transmission error vector magnitude (EVM). To evaluate the impact of nonlinearity on system performance, the signal to noise and distortion ratio (SNDR) is applied, defined as the linear sig⁃nal power over the thermal noise plus the front end nonlinear distortion. At a given noise level, the optimal system performance can be achieved by maximizing the SNDR, which results in high transmission rate or long transmission range for the VLC system. In this paper, we provide theoretical analysis on the optimization of SNDR with a nonlinear Hammerstein model of LED. Simula⁃tion results and lab experiments validate the theoretical analysis.
Modeling of unusual nonlinear behaviors in superconducting microstrip transmission lines
Energy Technology Data Exchange (ETDEWEB)
Javadzadeh, S. Mohammad Hassan, E-mail: smh_javadzadeh@ee.sharif.edu [School of Electrical Engineering, Sharif University of Technology, P.O. Box 11365-9363, Tehran (Iran, Islamic Republic of); Farzaneh, Forouhar; Fardmanesh, Mehdi [School of Electrical Engineering, Sharif University of Technology, P.O. Box 11365-9363, Tehran (Iran, Islamic Republic of)
2013-03-15
Highlights: ► Avoiding of considering just quadratic or modulus nonlinearity. ► Proposing a nonlinear model to predict unusual nonlinear behaviors at low temperatures. ► Description of temperature dependency of nonlinear behaviors in superconducting lines. ► Analytical formulation for each parameter in our proposed model. ► Obtaining very good results which shows this model can predict unusual nonlinear behavior. -- Abstract: There are unusual nonlinear behaviors in superconducting materials, especially at low temperatures. This paper describes the procedure to reliably predict this nonlinearity in superconducting microstrip transmission lines (SMTLs). An accurate nonlinear distributed circuit model, based on simultaneously considering of both quadratic and modulus nonlinearity dependences, is proposed. All parameters of the equivalent circuit can be calculated analytically using proposed closed-form expressions. A numerical method based on Harmonic Balance approach is used to predict nonlinear phenomena like intermodulation distortions and third harmonic generations. Nonlinear analyses of the SMTLs at the different temperatures and the input powers have been presented. This proposed model can describe the unusual behaviors of the nonlinearity at low temperatures, which are frequently observed in the SMTLs.
Royston, T. J.; Singh, R.
1996-07-01
While significant non-linear behavior has been observed in many vibration mounting applications, most design studies are typically based on the concept of linear system theory in terms of force or motion transmissibility. In this paper, an improved analytical strategy is presented for the design optimization of complex, active of passive, non-linear mounting systems. This strategy is built upon the computational Galerkin method of weighted residuals, and incorporates order reduction and numerical continuation in an iterative optimization scheme. The overall dynamic characteristics of the mounting system are considered and vibratory power transmission is minimized via adjustment of mount parameters by using both passive and active means. The method is first applied through a computational example case to the optimization of basic passive and active, non-linear isolation configurations. It is found that either active control or intentionally introduced non-linearity can improve the mount's performance; but a combination of both produces the greatest benefit. Next, a novel experimental, active, non-linear isolation system is studied. The effect of non-linearity on vibratory power transmission and active control are assessed via experimental measurements and the enhanced Galerkin method. Results show how harmonic excitation can result in multiharmonic vibratory power transmission. The proposed optimization strategy offers designers some flexibility in utilizing both passive and active means in combination with linear and non-linear components for improved vibration mounts.
Organic/Organometallic Hybrids as Broadband Nonlinear Transmission Materials
2010-06-01
property correlation in organometallic complexes in order to develop broadband nonlinear transmission materials . To realize this goal, we have...platinum complexes and 10 zinc phthalocyanine derivatives provided by collaborators in China. From these studies, we have discovered that in order to...in the near-IR region still limited their application as broadband nonlinear absorbing materials . To solve this problem, two approaches were
Transmission Characteristics Simulation on Power Line Communications
Kitayama, Masashi; Nakabayashi, Miyuki; Abe, Junichi; Tanabe, Shinji
In Power Line Communication (PLC) systems, medium and low voltage power distribution lines are used as a communication network. However, since no consideration is given to signal transmission characteristics in the high frequency used for PLC systems, reflections caused by impedance mismatches deteriorate transmission characteristics. If channel characteristics of power lines can be estimated by simulation, it will be efficient for the design and the operation of PLC networks. This paper proposes a method to estimate transmission characteristics of a channel model between a transmitter and a receiver installed on a distribution network. Propagation characteristics of PLC signals at each distribution facility is described using two port networks. A channel model is automatically generated from the combination of component models along the topology of distribution network and the locations of a transmitter and a receiver. The proposed method was validated using measurement data of a test distribution network and was proved to be effective.
Electric characterization of a nonlinear dispersive transmission line
Energy Technology Data Exchange (ETDEWEB)
Ferreira, E.S.; Ricotta, R.M. [Faculdade de Tecnologia de Sao Paulo (FATEC-SP), SP (Brazil)], Emails: ferreira@fatecsp.br, regina@fatecsp.br
2009-07-01
A preliminary study of electrical soliton propagation in a nonlinear dispersion electrical line is presented. This is probably the simplest system that allows the observation of such waves whose main characteristic is the perfect balance of nonlinear and dispersive aspects. (author)
Television signal transmission characteristics via BSE
Kozu, T.; Yamamoto, M.; Ohuchi, C.; Sugimoto, Y.; Fukuchi, H.
1986-01-01
The FM-TV signal transmission characteristics via BSE measured at the Main Transit and Receiving Station are described. Measurements are reported using 'standard parameters' which were carried out every half year from 1978 to 1980, measuring the video signal to noise ratio, waveform distortion, DG-DP, amplitude-frequency characteristics of video and audio signal, and the subjective assessment of video signal quality. These characteristics were good enough to broadcast a high-quality TV signal, and no degradation was observed for two years. Measurements using 'nonstandard parameters' were performed in order to study transmission parameters suitable for satellite broadcasting. Results are reported for one sound channel transmission using one FM subcarrier and for two sound channel transmission using two FM subcarriers.
Nonlinear transmission of an intense terahertz field through monolayer graphene
Directory of Open Access Journals (Sweden)
H. A. Hafez
2014-11-01
Full Text Available We report nonlinear terahertz (THz effects in monolayer graphene, giving rise to transmission enhancement of a single-cycle THz pulse when the incident THz peak electric field is increased. This transmission enhancement is attributed to reduced photoconductivity, due to saturation effects in the field-induced current and increased intraband scattering rates arising from transient heating of electrons. We have developed a tight-binding model of the response using the length gauge interaction Hamiltonian that provides good qualitative agreement. The model fully accounts for the nonlinear response arising from the linear dispersion energy spectrum in graphene. The results reveal a strong dependence of the scattering time on the THz field, which is at the heart of the observed nonlinear response.
Nonlinearities of biopolymer gels increase the range of force transmission
Xu, Xinpeng; Safran, Samuel A.
2015-09-01
We present a model of biopolymer gels that includes two types of elastic nonlinearities, stiffening under extension and softening (due to buckling) under compression, to predict the elastic anisotropy induced by both external as well as internal (e.g., due to cell contractility) stresses in biopolymer gels. We show how the stretch-induced anisotropy and the strain-stiffening nonlinearity increase both the amplitude and power-law range of transmission of internal, contractile, cellular forces, and relate this to recent experiments.
Institute of Scientific and Technical Information of China (English)
郜浩冬; 张以都; 吴琼; 高相胜
2013-01-01
考虑齿侧间隙、传动误差和时变啮合刚度等非线性因素,并同时考虑滑动轴承非线性油膜力和齿轮啮合力的耦合影响,建立了汇流传动齿轮-转子-轴承系统的动力学模型.从转速方面出发,研究了齿轮系统的非线性动态响应,分析了齿轮啮合力和非线性油膜力之间的耦合作用,判断了转速变化下的油膜稳定性.结果表明:随着转速变化,系统表现出周期一运动、周期二运动、拟周期运动,混沌等丰富的动力学特性,并发现了拟周期分岔通向混沌的道路；随着转速升高,非线性啮合力和菲线性油膜力先后对系统振动起到主要作用；油膜振动通过半频涡动失去了稳定性.%Considering nonlinear facters of backlash, transmission error,and time-varying mesh stiffness in a gear system, nonlinear mesh force of gear pairs and nonlinear oil film force of a journal bearing were considered synchronously, the dynamic model of a confluence transmission geared rotor bearing system was proposed. Starting from the variation of rotating speed, the nonlinear dynamic response of the gear system was studied, the coupling between the nonlinear gear mesh force and the nonlinear oil film force was discussed, the oil film's stability with the change of rotating speed was judged. The results indicated that with increase in rotating speed, the system reveals period one motion, period two motion,quasi- periodic motion and chaos motion, the way from quasi- periodic bifurcation to chaos was found; with increase in rotating speed, the nonlinear gear mesh force and the nonlinear oil film force affect the system vibration significantly; the oil film vibration loses stability through half frequency whirling motion.
Nonlinear properties of the lattice network-based nonlinear CRLH transmission lines
Institute of Scientific and Technical Information of China (English)
王正斌; 吴昭质; 高超
2015-01-01
The nonlinear properties of lattice network-based (LNB) composite right-/left-handed transmission lines (CRLH TLs) with nonlinear capacitors are experimentally investigated. Harmonic generation, subharmonic generation, and parametric excitation are clearly observed in an unbalanced LNB CRLH TL separately. While the balanced design of the novel nonlinear TL shows that the subharmonic generation and parametric processes can be suppressed, and almost the same power level of the higher harmonics can be achieved over a wide bandwidth range, which are difficult to find in the conventional CRLH TLs.
Nonlinear characteristics of an autoparametric vibration system
Yan, Zhimiao; Taha, Haithem E.; Tan, Ting
2017-03-01
The nonlinear characteristics of an autoparametric vibration system are investigated. This system consists of a base structure and a cantilever beam with a tip mass. The dynamic equations for the system are derived using the extended Hamilton's principle. The method of multiple scales (MMS) is used to determine an approximate analytical solution of the nonlinear governing equations and, hence, analyze the stability and bifurcation of the system. Compared with the numerical simulation, the first-order MMS is not sufficient. A Lagrangian-based approach is proposed to perform a second-order analysis, which is applicable to a large class of nonlinear systems. The effects of the amplitude and frequency of the external force, damping and frequency of the attached cantilever beam, and the tip mass on the nonlinear responses of the autoparametric vibration system are determined. The results show that this system exhibits many interesting nonlinear phenomena including saturation, jumps, hysteresis and different kinds of bifurcations, such as saddle-node, supercritical pitchfork and subcritical pitchfork bifurcations. Power spectra, phase portraits and Poincare maps are employed to analyze the unstable behavior and the associated Hopf bifurcation and chaos. Depending on the application of such a system, its dynamical behaviors could be exploited or avoided.
Institute of Scientific and Technical Information of China (English)
Z.-K.Peng; Z.-Q.Lang; G.Meng; S.A.Billings
2012-01-01
In the present study,the Volterra series theory is adopted to theoretically investigate the force transmissibility of multiple degrees of freedom (MDOF) structures,in which an isolator with nonlinear anti-symmetric viscous damping is assembled.The results reveal that the anti-symmetric nonlinear viscous damping can significantly reduce the force transmissibility over all resonance regions for MDOF structures with little effect on the transmissibility over non-resonant and isolation regions.The results indicate that the vibration isolators with an anti-symmetric damping characteristic have great potential to solve the dilemma occurring in the design of linear viscously damped vibration isolators where an increase of the damping level reduces the force transmissibility over resonant frequencies but increases the transmissibility over non-resonant frequency regions.This work is an extension of a previous study in which MDOF structures installed on the mount through an isolator with cubic nonlinear damping are considered.The theoretical analysis results are also verified by simulation studies.
Analysis of Bifurcation and Nonlinear Control for Chaos in Gear Transmission System
Directory of Open Access Journals (Sweden)
Wang Jingyue
2013-07-01
Full Text Available In order to study the bifurcation characteristics and control chaotic vibration of the gear transmission system. The complex dynamics characters of gear transmission system are studied. The dynamical equation and the state equation of gear transmission system are established according to Newton's rule. The route to chaos of the system is studied by the bifurcation diagram, phase portrait, time course diagram and Poincaré map. A method of controlling chaos by nonlinear feedback controller is developed to guide chaotic motions towards regular motions. Numerical simulation shows that with the increase of meshing stiffness, gear transmission system will be from the periodic motion to chaotic motion by doubling bifurcation, the effectiveness and feasibility of the strategy to get rid of chaos by stabilizing the related unstable periodic orbit.
Nonlinear Dynamic Characteristics of the Railway Vehicle
Uyulan, Çağlar; Gokasan, Metin
2017-06-01
The nonlinear dynamic characteristics of a railway vehicle are checked into thoroughly by applying two different wheel-rail contact model: a heuristic nonlinear friction creepage model derived by using Kalker 's theory and Polach model including dead-zone clearance. This two models are matched with the quasi-static form of the LuGre model to obtain more realistic wheel-rail contact model. LuGre model parameters are determined using nonlinear optimization method, which it's objective is to minimize the error between the output of the Polach and Kalker model and quasi-static LuGre model for specific operating conditions. The symmetric/asymmetric bifurcation attitude and stable/unstable motion of the railway vehicle in the presence of nonlinearities which are yaw damping forces in the longitudinal suspension system are analyzed in great detail by changing the vehicle speed. Phase portraits of the lateral displacement of the leading wheelset of the railway vehicle are drawn below and on the critical speeds, where sub-critical Hopf bifurcation take place, for two wheel-rail contact model. Asymmetric periodic motions have been observed during the simulation in the lateral displacement of the wheelset under different vehicle speed range. The coexistence of multiple steady states cause bounces in the amplitude of vibrations, resulting instability problems of the railway vehicle. By using Lyapunov's indirect method, the critical hunting speeds are calculated with respect to the radius of the curved track parameter changes. Hunting, which is defined as the oscillation of the lateral displacement of wheelset with a large domain, is described by a limit cycle-type oscillation nature. The evaluated accuracy of the LuGre model adopted from Kalker's model results for prediction of critical speed is higher than the results of the LuGre model adopted from Polach's model. From the results of the analysis, the critical hunting speed must be resolved by investigating the track tests
Vibration Isolation and Transmissibility Characteristics of Passive Sequential Damper
Directory of Open Access Journals (Sweden)
M.S. Patil
2004-01-01
Full Text Available This paper presents a half-car model (4-degrees-of-freedom employing nonlinear passlve sequential damper. The vibration isolation and transmrssibility effect on the vehicle's centre ofgravity (C.G. has been studied. The results have been compared for transmissibility, displacement, and velocity transient response for half-car model having nonlinear passive sequentialhydropneumatic damper under different terrain excitation.
Energy and Transmissibility in Nonlinear Viscous Base Isolators
Markou, Athanasios A.; Manolis, George D.
2016-09-01
High damping rubber bearings (HDRB) are the most commonly used base isolators in buildings and are often combined with other systems, such as sliding bearings. Their mechanical behaviour is highly nonlinear and dependent on a number of factors. At first, a physical process is suggested here to explain the empirical formula introduced by J.M. Kelly in 1991, where the dissipated energy of a HDRB under cyclic testing, at constant frequency, is proportional to the amplitude of the shear strain, raised to a power of approximately 1.50. This physical process is best described by non-Newtonian fluid behaviour, originally developed by F.H. Norton in 1929 to describe creep in steel at high-temperatures. The constitutive model used includes a viscous term, that depends on the absolute value of the velocity, raised to a non-integer power. The identification of a three parameter Kelvin model, the simplest possible system with nonlinear viscosity, is also suggested here. Furthermore, a more advanced model with variable damping coefficient is implemented to better model in this complex mechanical process. Next, the assumption of strain-rate dependence in their rubber layers under cyclic loading is examined in order to best interpret experimental results on the transmission of motion between the upper and lower surfaces of HDRB. More specifically, the stress-relaxation phenomenon observed with time in HRDB can be reproduced numerically, only if the constitutive model includes a viscous term, that depends on the absolute value of the velocity raised to a non-integer power, i. e., the Norton fluid previously mentioned. Thus, it becomes possible to compute the displacement transmissibility function between the top and bottom surfaces of HDRB base isolator systems and to draw engineering-type conclusions, relevant to their design under time-harmonic loads.
PROPAGATION CHARACTERISTICS OF ELECTROMAGNETIC WAVES IN GRADIENT TRANSMISSION LINE
Nesterov Iurii Gavriilovitch; Silin Nikolay Vitalievich
2015-01-01
Propagation characteristics of transmission lines with smooth continuous spatial distribution of capacitance and inductance (gradient transmission line) is considered in the framework of recently developed mathematical model. Strong heterogeneity-induced artificial dispersion is described by means of this model. Reflectance and transmittance spectra are shown on example of different gradient transmission lines. In conclusion, applicability of gradient transmission lines in areas o...
Cumulative signal transmission in nonlinear reaction-diffusion networks.
Directory of Open Access Journals (Sweden)
Diego A Oyarzún
Full Text Available Quantifying signal transmission in biochemical systems is key to uncover the mechanisms that cells use to control their responses to environmental stimuli. In this work we use the time-integral of chemical species as a measure of a network's ability to cumulatively transmit signals encoded in spatiotemporal concentrations. We identify a class of nonlinear reaction-diffusion networks in which the time-integrals of some species can be computed analytically. The derived time-integrals do not require knowledge of the solution of the reaction-diffusion equation, and we provide a simple graphical test to check if a given network belongs to the proposed class. The formulae for the time-integrals reveal how the kinetic parameters shape signal transmission in a network under spatiotemporal stimuli. We use these to show that a canonical complex-formation mechanism behaves as a spatial low-pass filter, the bandwidth of which is inversely proportional to the diffusion length of the ligand.
Explanation of the inverse Doppler effect observed in nonlinear transmission lines.
Kozyrev, Alexander B; van der Weide, Daniel W
2005-05-27
The theory of the inverse Doppler effect recently observed in magnetic nonlinear transmission lines is developed. We explain the crucial role of the backward spatial harmonic in the occurrence of an inverse Doppler effect and draw analogies of the magnetic nonlinear transmission line to the backward wave oscillator.
Reale, D V; Parson, J M; Neuber, A A; Dickens, J C; Mankowski, J J
2016-03-01
A stripline gyromagnetic nonlinear transmission line (NLTL) was constructed out of yttrium iron garnet ferrite and tested at charge voltages of 35 kV-55 kV with bias fields ranging from 10 kA/m to 20 kA/m. Typically, high power gyromagnetic NLTLs are constructed in a coaxial geometry. While this approach has many advantages, including a uniform transverse electromagnetic (TEM) mode, simple interconnection between components, and the ability to use oil or pressurized gas as an insulator, the coaxial implementation suffers from complexity of construction, especially when using a solid insulator. By moving to a simpler transmission line geometry, NLTLs can be constructed more easily and arrayed on a single substrate. This work represents a first step in exploring the suitability of various transmission line structures, such as microstrips and coplanar waveguides. The resulting high power microwave (HPM) source operates in ultra high frequency (UHF) band with an average bandwidth of 40.1% and peak rf power from 2 MW to 12.7 MW.
Institute of Scientific and Technical Information of China (English)
苏程
2012-01-01
The nonlinear dynamic model for a spur gear pair with single degree of freedom was established where in the tooth backlash, time-varying stiffness and comprehensive gearing error were comprehensively considered. The differential equations of motion with single degree of freedom were solved by employing variable step Runge-Kutta integration method. The dynamic characteristics of the system was analyzed for different tooth side clearance and varying mesh stiffness based on bifurcation diagrams, phase portraits, Poincare mapping and Fourier spectra. The result showed that the value of the tooth side clearance would have an influence on the critical value of system doubling bifurcation but no effect on system pitchfork bifurcation and its value..%建立综合考虑齿侧间隙、时变啮合刚度、综合啮合误差等因素下的直齿轮副的单自由度非线性动力学模型,利用变步长Runge-Kutta法对单自由度运动微分方程进行数值求解.结合系统的分岔图、相图、Poincaré映射图以及FFT频谱图,分析系统在不同侧隙值下,啮合刚度变化时的动力学特性,得到系统的混沌运动形成过程.结果表明侧隙值影响到系统倍化分岔的临界值,而对系统的叉式分岔及其分岔值没有影响.
Spectral characteristics and nonlinear studies of crystal violet dye
Sukumaran, V. Sindhu; Ramalingam, A.
2006-03-01
Solid-state dye-doped polymer is an attractive alternative to the conventional liquid dye solution. In this paper, the spectral characteristics and the nonlinear optical properties of the dye crystal violet are studied. The spectral characteristics of crystal violet dye doped poly(methylmethacrylate) modified with additive n-butyl acetate (nBA) are studied by recording its absorption and fluorescence spectra and the results are compared with the corresponding liquid mixture. The nonlinear refractive index of the dye in nBA and dye doped polymer film were measured using z-scan technique, by exciting with He-Ne laser. The results obtained are intercompared. Both the samples of dye crystal violet show a negative nonlinear refractive index. The origin of optical nonlinearity in the dye may be attributed due to laser-heating induced nonlinear effect.
Nonlinear inverse synthesis for high spectral efficiency transmission in optical fibers
Le, Son Thai; Turitsyn, Sergei K
2014-01-01
In linear communication channels, spectral components (modes) defined by the Fourier transform of the signal propagate without interactions with each other. In certain nonlinear channels, such as the one modelled by the classical nonlinear Schr\\"odinger equation, there are nonlinear modes (nonlinear signal spectrum) that also propagate without interacting with each other and without corresponding nonlinear cross talk; effectively, in a linear manner. Here, we describe in a constructive way how to introduce such nonlinear modes for a given input signal. We investigate the performance of the nonlinear inverse synthesis (NIS) method, in which the information is encoded directly onto the continuous part of the nonlinear signal spectrum. This transmission technique, combined with the appropriate distributed Raman amplification, can provide an effective eigenvalue division multiplexing with high spectral efficiency, thanks to highly suppressed channel cross talk. The proposed NIS approach can be integrated with any...
The study about planetary gearbox virtual prototyping with nonlinear gear contact characteristics
Yin, Huabing; Zhou, Guangming
2010-06-01
The virtual prototypes of gear transmission system built in most multi-body dynamic software have difficulties in describing the gear mesh characteristics. The gear mesh contact is modelled as rigid contact and this is not accurate for the gear mesh contact, which is elastic or flexible. The gear contact formula used in the multi-body dynamic software does not reveal the gear contact nonlinear stiffness characteristic. The model built with gear meshing contact is difficult to solve because of its time-consuming algorithm. In the paper a new method is put forward to build the virtual prototype of planetary gearbox system according to the nonlinear mesh stiffness and mesh phase obtained through FEM models. This new FEM method of gear mesh stiffness calculation is much more accurate than the common formulas. The gear mesh nonlinear stiffness of sun gear- pinion and pinion-ring gear of all the planetary gear sets in gearbox are obtained through MATALB code, which is used to read and plot the analyzing result data. The gear mesh phase differences between different pinions with suns or rings of different planetary gear set can be also obtained. With all these data modelled in simulink (or other software) and integrated with the multi-body dynamic planetary gearbox model and the gear meshing contact problem in multi-body gear models is solved easily and accurately. The interfaces for gear mesh stiffness and mesh phases are designed for multi-body dynamic model and simulink. The nonlinear planetary gear set prototyping models are integrated to become the whole planetary gear box model and the whole vehicle system model built in multi-body dynamic software can be integrated to simulate different duty conditions. At last high speed input is put into the nonlinear planetary transmission model and the different duty cases are simulated. The dynamic characteristics of different parts are obtained. The dynamic characteristic comparison between nonlinear and linear models is made
Nonlinear phase noise in coherent optical OFDM transmission systems.
Zhu, Xianming; Kumar, Shiva
2010-03-29
We derive an analytical formula to estimate the variance of nonlinear phase noise caused by the interaction of amplified spontaneous emission (ASE) noise with fiber nonlinearity such as self-phase modulation (SPM), cross-phase modulation (XPM), and four-wave mixing (FWM) in coherent orthogonal frequency division multiplexing (OFDM) systems. The analytical results agree very well with numerical simulations, enabling the study of the nonlinear penalties in long-haul coherent OFDM systems without extensive numerical simulation. Our results show that the nonlinear phase noise induced by FWM is significantly larger than that induced by SPM and XPM, which is in contrast to traditional WDM systems where ASE-FWM interaction is negligible in quasi-linear systems. We also found that fiber chromatic dispersion can reduce the nonlinear phase noise. The variance of the total phase noise increases linearly with the bit rate, and does not depend significantly on the number of subcarriers for systems with moderate fiber chromatic dispersion.
Nonlinear dynamical characteristics of bed load motion
Institute of Scientific and Technical Information of China (English)
BAI; Yuchuan; XU; Haijue; XU; Dong
2006-01-01
Bed forms of various kinds that evolve naturally on the bottom of sandy coasts and rivers are a result of the kinematics of bed load transport. Based on the group motion of particles in the bed load within the bottom layer, a study on the nonlinear dynamics of bed load transport is presented in this paper. It is found that some development stages, such as the initiation, the equilibrium sediment transport, and the transition from a smooth bed to sand dunes, can be accounted for by different states in the nonlinear system of the bed load transport. It is verified by comparison with experimental data reported by Laboratoire Nationae D'Hydraulique, Chatou, France, that the evolution from a smooth bed to sand dunes is determined by mutation in the bed load transport. This paper presents results that may offer theoretical explanations to the experimental observations. It is also an attempt to apply the state-of-the-art nonlinear science to the classical sediment transport mechanics.
Exact Solutions for a Local Fractional DDE Associated with a Nonlinear Transmission Line
Aslan, İsmail
2016-09-01
Of recent increasing interest in the area of fractional calculus and nonlinear dynamics are fractional differential-difference equations. This study is devoted to a local fractional differential-difference equation which is related to a nonlinear electrical transmission line. Explicit traveling wave solutions (kink/antikink solitons, singular, periodic, rational) are obtained via the discrete tanh method coupled with the fractional complex transform.
Schuh, Fabian
2012-01-01
In this paper we propose a matched decoding scheme for convolutionally encoded transmission over intersymbol interference (ISI) channels and devise a nonlinear trellis description. As an application we show that for coded continuous phase modulation (CPM) using a non-coherent receiver the number of states of the super trellis can be significantly reduced by means of a matched non-linear trellis encoder.
Intra-Channel Nonlinear Effect on Optical PPM Pulse Transmission
Institute of Scientific and Technical Information of China (English)
Sun; Linghao; Jarmo; Takala
2003-01-01
PPM encoded Gaussian pulse sequence shows more immunity than non-PPM schemes on optical fiber intra-channel nonlinearity and demonstrated by a numerical study of IXPM and IFWM effects deploying on 100Gb/s single channelsystem.
Institute of Scientific and Technical Information of China (English)
Wenhua Cao; Songhao Liu
2005-01-01
Stable picosecond soliton transmission is demonstrated numerically by use of concatenated gain-distributed nonlinear amplifying fiber loop mirrors (NALMs). We show that, as compared with previous soliton transmission schemes that use conventional NALMs or nonlinear optical loop mirror (NOLM) and amplifier combinations, the present scheme permits significant increase of loop-mirror (amplifier) spacing. The broad switching window of the present device and the high quality pulses switched from it provide a reasonable stability range for soliton transmission. Soliton-soliton interactions can be reduced efficiently by using lowly dispersive fibers.
Nonlinear – characteristics study of doped SnO2
Indian Academy of Sciences (India)
S R Dhage; V Ravi; S K Date
2004-02-01
When tin oxide is doped with Sb2O3 and CoO, it shows highly nonlinear current ()–voltage () characteristics. Addition of CoO leads to creation of oxygen vacancies and helps in sintering of SnO2. Antimony oxide acts as a donor and increases the conductivity. The results are nearly the same when antimony oxide is replaced by tantalum oxide. The observed nonlinear coefficient, = 30 and the breakdown voltage is 120 V/mm.
NONLINEAR DYNAMICAL CHARACTERISTICS OF PILES UNDER HORIZONTAL VIBRATION
Institute of Scientific and Technical Information of China (English)
HU Yu-jia; CHENG Chang-jun; YANG Xiao
2005-01-01
The pile-soil system is regarded as a visco-elastic half-space embedded pile. Based on the method of continuum mechanics, a nonlinear mathematical model of pilesoil interaction was established-a coupling nonlinear boundary value problem. Under the case of horizontal vibration, the nonlinearly dynamical characteristics of pile applying the axis force were studied in horizontal direction in frequency domain. The effects of parameters, especially the axis force on the stiffness were studied in detail. The numerical results suggest that it is possible that the pile applying an axis force will lose its stability. So, the effect of the axis force on the pile is considered.
Srivastava, Nilabh; Haque, Imtiaz
2009-03-01
Over the past two decades, extensive research has been conducted on developing vehicle transmissions that meet the goals of reduced exhaust emissions and increased vehicle efficiency. A continuously variable transmission is an emerging automotive transmission technology that offers a continuum of gear ratios between desired limits. A chain CVT is a friction-limited drive whose dynamic performance and torque capacity rely significantly on the friction characteristic of the contact patch between the chain and the pulley. Although a CVT helps to maximize the vehicle fuel economy, its complete potential has not been accomplished in a mass-production vehicle. The present research focuses on developing models to analyze friction-induced nonlinear dynamics of a chain CVT drive and identify possible mechanisms that cause degradation of the overall dynamic performance by inducing chaos and self-sustained vibrations in the system. Two different mathematical models of friction, which characterize different operating or loading conditions, are embedded into a detailed planar multibody model of chain CVT in order to capture the various friction-induced effects in the system. Tools such as stick-slip oscillator dynamics, Lyapunov exponents, phase-space reconstruction, and recurrence plotting are incorporated to characterize the nonlinear dynamics of such a friction-limited system. The mathematical models, the computational scheme, and the results corresponding to different loading scenarios are discussed. The results discuss the influence of friction characteristics on the nonlinear dynamics and torque transmitting capacity of a chain CVT drive.
Nonlinear Dynamic Characteristics of Oil-in-Water Emulsions
Yin, Zhaoqi; Han, Yunfeng; Ren, Yingyu; Yang, Qiuyi; Jin, Ningde
2016-08-01
In this article, the nonlinear dynamic characteristics of oil-in-water emulsions under the addition of surfactant were experimentally investigated. Firstly, based on the vertical upward oil-water two-phase flow experiment in 20 mm inner diameter (ID) testing pipe, dynamic response signals of oil-in-water emulsions were recorded using vertical multiple electrode array (VMEA) sensor. Afterwards, the recurrence plot (RP) algorithm and multi-scale weighted complexity entropy causality plane (MS-WCECP) were employed to analyse the nonlinear characteristics of the signals. The results show that the certainty is decreasing and the randomness is increasing with the increment of surfactant concentration. This article provides a novel method for revealing the nonlinear dynamic characteristics, complexity, and randomness of oil-in-water emulsions with experimental measurement signals.
Kong, Chao; Hai, Kuo; Tan, Jintao; Chen, Hao; Hai, Wenhua
2016-03-01
Nonlinear Kronig-Penney model has been frequently employed to study transmission problem of electron wave in a doped semiconductor superlattice or in a nonlinear electrified chain. Here from an integral equation we derive a novel exact solution of the problem, which contains a simple nonlinear map connecting transmission coefficient with system parameters. Consequently, we propose a scheme to manipulate electronic distribution and transmission by adjusting the system parameters. A new quantum coherence effect is evidenced by the strict expression of transmission coefficient, which results in the aperiodic electronic distributions and different transmission coefficients including the approximate zero transmission and total transmission, and the multiple transmissions. The method based on the concise exact solution can be applied directly to some nonlinear cold atomic systems and a lot of linear Kronig-Penney systems, and also can be extended to investigate electronic transport in different discrete nonlinear systems.
Experimental Demonstration of Nonlinear Frequency Division Multiplexed Transmission
Aref, Vahid; Schuh, Karsten; Idler, Wilfried
2015-01-01
We experimentally demonstrate an NFDM optical system with modulation over nonlinear discrete spectrum. Particularly, each symbol carries 4-bits from multiplexing two eigenvalues modulated by QPSK constellation. We show a low error performance using NFT detection with 4Gbps rate over 640km.
Control of terahertz nonlinear transmission with electrically gated graphene metadevices
Choi, Hyun Joo; Baek, In Hyung; Kang, Bong Joo; Kim, Hyeon-Don; Oh, Sang Soon; Hamm, Joachim M.; Pusch, Andreas; Park, Jagang; Lee, Kanghee; Son, Jaehyeon; Jeong, Young U. K.; Hess, Ortwin; Rotermund, Fabian; Min, Bumki
2017-02-01
Graphene, which is a two-dimensional crystal of carbon atoms arranged in a hexagonal lattice, has attracted a great amount of attention due to its outstanding mechanical, thermal and electronic properties. Moreover, graphene shows an exceptionally strong tunable light-matter interaction that depends on the Fermi level - a function of chemical doping and external gate voltage - and the electromagnetic resonance provided by intentionally engineered structures. In the optical regime, the nonlinearities of graphene originated from the Pauli blocking have already been exploited for mode-locking device applications in ultrafast laser technology, whereas nonlinearities in the terahertz regime, which arise from a reduction in conductivity due to carrier heating, have only recently been confirmed experimentally. Here, we investigated two key factors for controlling nonlinear interactions of graphene with an intense terahertz field. The induced transparencies of graphene can be controlled effectively by engineering meta-atoms and/or changing the number of charge carriers through electrical gating. Additionally, nonlinear phase changes of the transmitted terahertz field can be observed by introducing the resonances of the meta-atoms.
Control of terahertz nonlinear transmission with electrically gated graphene metadevices
Choi, Hyun Joo; Baek, In Hyung; Kang, Bong Joo; Kim, Hyeon-Don; Oh, Sang Soon; Hamm, Joachim M.; Pusch, Andreas; Park, Jagang; Lee, Kanghee; Son, Jaehyeon; Jeong, Young U. k.; Hess, Ortwin; Rotermund, Fabian; Min, Bumki
2017-01-01
Graphene, which is a two-dimensional crystal of carbon atoms arranged in a hexagonal lattice, has attracted a great amount of attention due to its outstanding mechanical, thermal and electronic properties. Moreover, graphene shows an exceptionally strong tunable light-matter interaction that depends on the Fermi level - a function of chemical doping and external gate voltage - and the electromagnetic resonance provided by intentionally engineered structures. In the optical regime, the nonlinearities of graphene originated from the Pauli blocking have already been exploited for mode-locking device applications in ultrafast laser technology, whereas nonlinearities in the terahertz regime, which arise from a reduction in conductivity due to carrier heating, have only recently been confirmed experimentally. Here, we investigated two key factors for controlling nonlinear interactions of graphene with an intense terahertz field. The induced transparencies of graphene can be controlled effectively by engineering meta-atoms and/or changing the number of charge carriers through electrical gating. Additionally, nonlinear phase changes of the transmitted terahertz field can be observed by introducing the resonances of the meta-atoms. PMID:28216677
Q-factor analysis of nonlinear impairments in ultrahigh-speed Nyquist pulse transmission.
Hirooka, Toshihiko; Nakazawa, Masataka
2015-12-28
We present detailed analytical and numerical results of the dispersion and nonlinear tolerances of RZ and Nyquist optical pulses in ultrahigh-speed TDM transmissions. From a Q-map analysis, i.e. by numerically calculating the Q-factor distribution as a function of transmission power and fiber dispersion, we found that Nyquist TDM transmission has a substantially larger Q margin as regards both dispersion and optical power thanks to ISI-free overlapped TDM. We also show that the optimum transmission power for Nyquist pulses is 2 dB lower than for RZ pulses. An analytical model is provided to explain the overlap-induced nonlinear impairments in Nyquist TDM transmission in a high power regime, which agrees well with numerical results.
Nonlinear Characteristics of Randomly Excited Transonic Flutter
DEFF Research Database (Denmark)
Christiansen, Lasse Engbo; Lehn-Schiøler, Tue; Mosekilde, Erik
2002-01-01
shown that the self-sustained oscillations arise in a subcritical Hopf bifurcation. However, analysis of the experimental data also reveals that this bifurcation is modified in various ways. We present an outline of the construction of a 6 DOF model of the aeroelastic behavior of the wing structure...... reproduce several of the experimentally observed modifications of the flutter transition. In particular, the models display the characteristic phenomena of coherence resonance....
Energy Technology Data Exchange (ETDEWEB)
Russell, Steven J. [Los Alamos National Laboratory; Carlsten, Bruce E. [Los Alamos National Laboratory
2012-06-26
We will quickly go through the history of the non-linear transmission lines (NLTLs). We will describe how they work, how they are modeled and how they are designed. Note that the field of high power, NLTL microwave sources is still under development, so this is just a snap shot of their current state. Topics discussed are: (1) Introduction to solitons and the KdV equation; (2) The lumped element non-linear transmission line; (3) Solution of the KdV equation; (4) Non-linear transmission lines at microwave frequencies; (5) Numerical methods for NLTL analysis; (6) Unipolar versus bipolar input; (7) High power NLTL pioneers; (8) Resistive versus reactive load; (9) Non-lineaer dielectrics; and (10) Effect of losses.
Vibration transmissibility characteristics of smart spring vibration isolation system
Institute of Scientific and Technical Information of China (English)
倪德; 朱如鹏; 陆凤霞; 鲍和云; 付秋菊
2014-01-01
The objective of this work was to study the vibration transmissibility characteristics of the undamped and damped smart spring systems. The frequency response characteristics of them were analyzed by using the equivalent linearization technique, and the possible types of the system motion were distinguished by using the starting and ending frequencies. The influences of system parameters on the vibration transmissibility characteristics were discussed. The following conclusions may be drawn from the analysis results. The undamped smart spring system may simultaneously have one starting frequency and one ending frequency or only have one starting frequency, and the damped system may simultaneously have two starting frequencies and one ending frequency. There is an optimal control parameter to make the peak value of the vibration transmissibility curve of the system be minimum. When the mass ratio is far away from the stiffness ratio, the vibration transmissibility is small. The effect of the damping ratio on the system vibration transmissibility is significant while the control parameter is less than its optimal value. But the influence of the relative damping ratio on the vibration transmissibility is small.
Institute of Scientific and Technical Information of China (English)
Jeong Ja Bae
2012-01-01
In this article,we consider the global existence and decay rates of solutions for the transmission problem of Kirchhoff type wave equations consisting of two physically different types of materials,one component is a Kirchhoff type wave equation with nonlinear time dependent localized dissipation which is effective only on a neighborhood of certain part of the boundary,while the other is a Kirchhoff type wave equation with nonlinear memory.
Parametric characteristic of the random vibration response of nonlinear systems
Institute of Scientific and Technical Information of China (English)
Xing-Jian Dong; Zhi-Ke Peng; Wen-Ming Zhang; Guang Meng; Fu-Lei Chu
2013-01-01
Volterra series is a powerful mathematical tool for nonlinear system analysis,and there is a wide range of non-linear engineering systems and structures that can be represented by a Volterra series model.In the present study,the random vibration of nonlinear systems is investigated using Volterra series.Analytical expressions were derived for the calculation of the output power spectral density (PSD) and input-output cross-PSD for nonlinear systems subjected to Gaussian excitation.Based on these expressions,it was revealed that both the output PSD and the input-output crossPSD can be expressed as polynomial functions of the nonlinear characteristic parameters or the input intensity.Numerical studies were carried out to verify the theoretical analysis result and to demonstrate the effectiveness of the derived relationship.The results reached in this study are of significance to the analysis and design of the nonlinear engineering systems and structures which can be represented by a Volterra series model.
TRANSIENT ANALYSIS OF NONUNIFORM TRANSMISSION LINES WITH NONLINEAR TERMINAL NETWORKS
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
A semi-analytical method in time domain is presented for analysis of the transient response of nonuniform transmission lines. In this method, the telegraph equations in time domain is differenced in space domain first, and is transformed into a set of first-order differential equations of voltage and current with respect to time. By integrating these differential equations with respect to time, and precise computation, the solution of these differential equations can be obtained. This method can solve the transient response of various kinds of transmission lines with arbitrary terminal networks. Particularly, it can analyze the nonuniform lines with initial conditions, for which there is no existing effective method to analyze the time response so far. The results obtained with this method are stable and accurate. Two examples are given to illustrate the application of this method.
Understanding the Percolation Characteristics of Nonlinear Composite Dielectrics
Yang, Xiao; Hu, Jun; Chen, Shuiming; He, Jinliang
2016-08-01
Nonlinear composite dielectrics can function as smart materials for stress control and field grading in all fields of electrical insulations. The percolation process is a significant issue of composite dielectrics. However, the classic percolation theory mainly deals with traditional composites in which the electrical parameters of both insulation matrix and conducting fillers are independent of the applied electric field. This paper measured the nonlinear V-I characteristics of ZnO microvaristors/silicone rubber composites with several filler concentrations around an estimated percolation threshold. For the comparison with the experiment, a new microstructural model is proposed to simulate the nonlinear conducting behavior of the composite dielectrics modified by metal oxide fillers, which is based on the Voronoi network and considers the breakdown feature of the insulation matrix for near percolated composites. Through both experiment and simulation, the interior conducting mechanism and percolation process of the nonlinear composites were presented and a specific percolation threshold was determined as 33%. This work has provided a solution to better understand the characteristics of nonlinear composite dielectrics.
Energy Technology Data Exchange (ETDEWEB)
Nguyen, Ba Phi [Central University of Construction, Tuy Hoa (Viet Nam); Kim, Ki Hong [Ajou University, Suwon (Korea, Republic of)
2014-06-15
We study theoretically the influence of nonlinear gain effects on the transmission and the Anderson localization of waves in both uniform and random one-dimensional amplifying media by using the discrete nonlinear Schroedinger equation. In uniform amplifying media with nonlinear gain, we find that the strong oscillatory behavior of the transmittance and the reflectance for odd and even values of the sample length disappears for large nonlinearities. The exponential decay rate of the transmittance in the asymptotic limit is found to be independent of nonlinear gain. In random amplifying media, we find that the maximum values of the disorder-averaged logarithmic transmittance and reflectance depend nonmonotonically on the strength of nonlinear gain. We also find that the localization length is independent of nonlinear gain. In other words, the Anderson localization is neither enhanced nor weakened due to nonlinear gain. In both the uniform and the random cases, the crossover length, which is the critical length for the amplification to be efficient, is strongly reduced by the nonlinear nature of the gain.
Method for Measuring Small Nonlinearities of Electric Characteristics
DEFF Research Database (Denmark)
Guldbrandsen, Tom; Meyer, Niels I; Schjær-Jacobsen, Jørgen
1965-01-01
A method is described for measuring very small deviations from linearity in electric characteristics. The measurement is based on the harmonics generated by the nonlinear element when subjected to a sine wave signal. A special bridge circuit is used to balance out the undesired harmonics...... of the signal generator together with the first harmonic frequency. The set-up measures the small-signal value and the first and second derivative with respect to voltage. The detailed circuits are given for measuring nonlinearities in Ohmic and capacitive components. In the Ohmic case, a sensitivity...
Pakarzadeh, H.; Rezaei, S. M.
2016-01-01
In this article, we investigate for the first time the dispersion and the nonlinear characteristics of the tapered photonic crystal fibers (PCFs) as a function of length z, via solving the eigenvalue equation of the guided mode using the finite-difference frequency-domain method. Since the structural parameters such as the air-hole diameter and the pitch of the microstructured cladding change along the tapered PCFs, dispersion and nonlinear properties change with the length as well. Therefore, it is important to know the exact behavior of such fiber parameters along z which is necessary for nonlinear optics applications. We simulate the z dependency of the zero-dispersion wavelength, dispersion slope, effective mode area, nonlinear parameter, and the confinement loss along the tapered PCFs and propose useful relations for describing dispersion and nonlinear parameters. The results of this article, which are in a very good agreement with the available experimental data, are important for simulating pulse propagation as well as investigating nonlinear effects such as supercontinuum generation and parametric amplification in tapered PCFs.
Analysis for the Dynamic Characteristic of the Automobile Transmission Gearbox
Directory of Open Access Journals (Sweden)
Fujin Yu
2013-02-01
Full Text Available Automobile transmission gearbox, as one of the major components, which will inevitably bring about the vibration and noise of automobile vehicle. The objective of this study to reduce the noise and vibration of automobile transmission by structural optimization of the gearbox in order to better control its functional operation and improve its performance. For this purpose, based on the working characteristics of the gearbox, modal analysis of automobile transmission gearbox is formulated using 3D graphics software Pro/E together with Finite Element Method. In addition, the modal test of gearbox is conducted also. Through comparing model analysis results to test results, test results verify the correctness of the finite element analysis results, thus provide the theoretic basis to analyze its dynamic characteristics of the gearbox structure as well as its improvement to reduce vibration and noise.
Characteristics on Hydro-mechanical Transmission in Power Shift Process
Institute of Scientific and Technical Information of China (English)
HU Jibin; WEI Chao; YUAN Shihua; JING Chongbo
2009-01-01
To improve the vehicular power and acceleration performance and reduce the shift impact, the study of the characteristics on power shift is necessary. Based on the flexible hydraulic unit of hydro-mechanical transmission, this paper explores the feasibility of shift without power interruption. With the four models concerning displacement ratio, rotational speed, rotational torque and power at ideal shift point, the characteristics on power shift in different running conditions are analyzed, and the rules of power shift are revealed.The theoretical analysis and test results show that the hydro-mechanical transmission can shift without power interruption in different running conditions. Furthermore, there exists an ideal shift point in theory, at which point the cycle power in hydro-mechanical transmission can't be generated, and the impact on the system can be reduced to the minimum. However, if before or after this ideal shift point, a cycle power can be generated.
DEFF Research Database (Denmark)
Yu, Yi; Chen, Yaohui; Hu, Hao;
2015-01-01
We suggest and experimentally demonstrate a photonic-crystal structure with more than 30 dB difference between forward and backward transmission levels. The non-reciprocity relies on the combination of ultrafast carrier nonlinearities and spatial symmetry breaking in a Fano structure employing...
Modulational Instability in a Pair of Non-identical Coupled Nonlinear Electrical Transmission Lines
Institute of Scientific and Technical Information of China (English)
Eric Tala-Tebue; Aurelien Kenfack-Jiotsa; Marius Hervé Tatchou-Ntemfack; Timoléon Crépin Kofané
2013-01-01
In this work,we investigate the dynamics of modulated waves non-identical coupled nonlinear transmission lines.Traditional methods for avoiding mode mixing in identical coupled nonlinear electrical lines consist of adding the same number of linear inductors in each branch.Adding linear inductors in a single line leads to asymmetric coupled nonlinear electrical transmission lines which propagate the signal and the mode mixing.On one hand,the difference between the two lines induced the fission for only one mode of propagation.This fission is influenced by the amplitude of the signal and the amount of the input energy as well; it also narrows the width of the input pulse soliton,leading to a possible increasing of the bit rate.On the other hand,the dissymmetry of the two lines converts the network into a good amplifier for the w_ mode which corresponds to the regime admitting low frequencies.
Peculiar Transmission Characteristics of the Large Gap Semi-Insulating GaAs Photoconductive Switch
Institute of Scientific and Technical Information of China (English)
施卫; 马湘蓉
2011-01-01
Unique experimental phenomena are discovered in a large gap semiinsulating(SI)GaAs photoconductive semiconductor switch(PCSS)and the peculiar transmission characteristics are exhibited in the experiment.The transmission characteristics for the large gap SI-GaAs PCSS are entirely different from the commonly designed PCSS.By analyzing the differences of the transmission characteristics between the common and the large gap SI-GaAs PCSS,a detailed statistical analysis and theoretical explanations are expounded.The large gap SI-GaAs PCSS works in the overvoltage relaxation limit space charge accumulation(LSA)mode when the conditions of 5 × 104 s·cm-3 ≤ no/f ≤ 3 × 105 s.cm-3 and noL ≥ 1013 cm-2 must be met in the switch,with no being carrier concentration and f the frequency.The large gap SI-GaAs PCSS we developed has not shown the nonlinear (lock-in)behavior at high bias voltage,so the withstand voltage and service life for PCSS are improved.%Unique experimental phenomena are discovered in a large gap semiinsulating (SI) GaAs photoconductive semiconductor switch (PCSS) and the peculiar transmission characteristics are exhibited in the experiment. The transmission characteristics for the large gap SI-GaAs PCSS are entirely different from the commonly designed PCSS. By analyzing the differences of the transmission characteristics between the common and the large gap SI-GaAs PCSS, a detailed statistical analysis and theoretical explanations are expounded. The large gap SI-GaAs PCSS works in the overvoltage relaxation limit space charge accumulation (LSA) mode when the conditions of 5 x 104 s-cm~3 1013 cm~2 must be met in the switch, with no being carrier concentration and f the frequency. The large gap SI-GaAs PCSS we developed has not shown the nonlinear (lock-in) behavior at high bias voltage, so the withstand voltage and service life for PCSS are improved.
Nonlinear Dynamic Characteristics of Combustion Wave in SHS Process
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
The characteristic of combustion wave and its change were analyzed by numerical value calculation and computer simulation,based on the combustion dynamical model of SHS process. It is shown that with the change of condition parameters in SHS process various time-space order combustion waves appear.It is concluded from non-liner dynamical mechanism analysis that the strong coupling of two non-linear dynamical processes is the dynamical mechanism causing the time-space order dissipation structures.
de Aguiar, Hilton B; Brasselet, Sophie
2016-01-01
Despite the tremendous progresses in wavefront control through or inside complex scattering media, several limitations prevent reaching practical feasibility for nonlinear imaging in biological tissues. While the optimization of nonlinear signals might suffer from low signal to noise conditions and from possible artifacts at large penetration depths, it has nevertheless been largely used in the multiple scattering regime since it provides a guide star mechanism as well as an intrinsic compensation for spatiotemporal distortions. Here, we demonstrate the benefit of Transmission Matrix (TM) based approaches under broadband illumination conditions, to perform nonlinear imaging. Using ultrashort pulse illumination with spectral bandwidth comparable but still lower than the spectral width of the scattering medium, we show strong nonlinear enhancements of several orders of magnitude, through thicknesses of a few transport mean free paths, which corresponds to millimeters in biological tissues. Linear TM refocusing ...
Capacity estimates for optical transmission based on the nonlinear Fourier transform
Derevyanko, Stanislav A.; Prilepsky, Jaroslaw E.; Turitsyn, Sergei K.
2016-09-01
What is the maximum rate at which information can be transmitted error-free in fibre-optic communication systems? For linear channels, this was established in classic works of Nyquist and Shannon. However, despite the immense practical importance of fibre-optic communications providing for >99% of global data traffic, the channel capacity of optical links remains unknown due to the complexity introduced by fibre nonlinearity. Recently, there has been a flurry of studies examining an expected cap that nonlinearity puts on the information-carrying capacity of fibre-optic systems. Mastering the nonlinear channels requires paradigm shift from current modulation, coding and transmission techniques originally developed for linear communication systems. Here we demonstrate that using the integrability of the master model and the nonlinear Fourier transform, the lower bound on the capacity per symbol can be estimated as 10.7 bits per symbol with 500 GHz bandwidth over 2,000 km.
L1 adaptive control of uncertain gear transmission servo systems with deadzone nonlinearity.
Zuo, Zongyu; Li, Xiao; Shi, Zhiguang
2015-09-01
This paper deals with the adaptive control problem of Gear Transmission Servo (GTS) systems in the presence of unknown deadzone nonlinearity and viscous friction. A global differential homeomorphism based on a novel differentiable deadzone model is proposed first. Since there exist both matched and unmatched state-dependent unknown nonlinearities, a full-state feedback L1 adaptive controller is constructed to achieve uniformly bounded transient response in addition to steady-state performance. Finally, simulation results are included to show the elimination of limit cycles, in addition to demonstrating the main results in this paper.
Directory of Open Access Journals (Sweden)
Zhenhua Yan
2015-01-01
Full Text Available Low-frequency vibrations (0.5–5 Hz that harm drivers occur in off-road vehicles. Thus, researchers have focused on finding methods to effectively isolate or control low-frequency vibrations. A novel nonlinear seat suspension structure for off-road vehicles is designed, whose static characteristics and seat-human system dynamic response are modeled and analyzed, and experiments are conducted to verify the theoretical solutions. Results show that the stiffness of this nonlinear seat suspension could achieve real zero stiffness through well-matched parameters, and precompression of the main spring could change the nonlinear seat suspension performance when a driver’s weight changes. The displacement transmissibility curve corresponds with the static characteristic curve of nonlinear suspension, where the middle part of the static characteristic curve is gentler and the resonance frequency of the displacement transmissibility curve and the isolation minimum frequency are lower. Damping should correspond with static characteristics, in which the corresponding suspension damping value should be smaller given a flatter static characteristic curve to prevent vibration isolation performance reduction.
2015-08-27
The high voltage diodes D5 to D10 are used to protect the HV switch against negative back swing voltage, while D4 diode for reverse current ...AFRL-AFOSR-CL-TR-2015-0001 STUDY OF HV DIELECTRICS FOR HIGH FREQUENCY OPERATION IN LINEAR & NONLINEAR TRANSMISSION LINES & SIMULATION & DEVELOPMENT...AFOSR Final Performance Report Study of HV Dielectrics for High Frequency Operation in Linear and Nonlinear Transmission Lines and Simulation
Spectral characteristics of Compton backscattering sources. Linear and nonlinear modes
Energy Technology Data Exchange (ETDEWEB)
Potylitsyn, A.P., E-mail: potylitsyn@tpu.ru [National Research Tomsk Polytechnic University, 634050 Tomsk (Russian Federation); National Research Nuclear University MEPhI, 115409 Moscow (Russian Federation); Kolchuzhkin, A.M. [Moscow State University of Technology “STANKIN”, 127994 Moscow (Russian Federation)
2015-07-15
Compton backscattering (CBS) of laser photons by relativistic electrons is widely used to design X-ray and gamma sources with a bandwidth better than 1% using a tight collimation. In order to obtain a reasonable intensity of the resulting beam one has to increase power of a laser pulse simultaneously with narrowing of the waist in the interaction point. It can lead to nonlinearity of CBS process which is affected on spectral characteristics of the collimated gamma beam (so-called “red-shift” of the spectral line, emission of “soft” photons with energy much less than the spectral line energy). In this paper we have analyzed such an influence using Monte-Carlo technique and have shown that even weak nonlinearity should be taken into account if the gamma beam is formed by a narrow aperture.
Thermal and Transmission Properties of UV Nonlinear Optical Material-- ZnCd(SCN)4 Crystal
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
Zinc cadmium thiocyanate(ZCTC), ZnCd(SCN)4, has been discovered as a UV second-order nonlinear optical coordination crystal. Its thermal and transmission properties are reported. The thermal decomposition is characterized by using the X-ray powder diffraction (XRPD) and infrared (IR) spectroscopy at room temperature. The absorptions of intrinsic ions and ZCTC in a solution state are discussed as well as transmission properties of the ZCTC crystal. An effective method of reducing the surface reflection loss of ZCTC crystal is introduced.
Skidin, Anton S; Sidelnikov, Oleg S; Fedoruk, Mikhail P; Turitsyn, Sergei K
2016-12-26
The impact of the fiber Kerr effect on error statistics in the nonlinear (high power) transmission of the OFDM 16-QAM signal over a 2000 km EDFA-based link is examined. We observed and quantified the difference in the error statistics for constellation points located at three power-defined rings. Theoretical analysis of a trade-off between redundancy and error rate reduction using probabilistic coding of three constellation power rings decreasing the symbol-error rate of OFDM 16-QAM signal is presented. Based on this analysis, we propose to mitigate the nonlinear impairments using the adaptive modulation technique applied to the OFDM 16-QAM signal. We demonstrate through numerical modelling the system performance improvement by the adaptive modulation for the large number of OFDM subcarriers (more than 100). We also show that a similar technique can be applied to single carrier transmission.
ON TRANSMISSION PROBLEM FOR VISCOELASTIC WAVE EQUATION WITH A LOCALIZED A NONLINEAR DISSIPATION
Institute of Scientific and Technical Information of China (English)
Jeong Ja BAE; Seong Sik KIM
2013-01-01
In this article,we consider the global existence and decay rates of solutions for the transmission problem of Kirchhoff type wave equations consisting of two physically different types of materials,one component being a Kirchhoff type wave equation with time dependent localized dissipation which is effective only on a neighborhood of certain part of boundary,while the other being a Kirchhoff type viscoelastic wave equation with nonlinear memory.
The Influence of the Balance of Dispersion and Nonlinearity on the Transmission Quality in Fiber
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
This article analyzes the effect of the balance of dispersion and nonlinearity on the quality of a transmission system with super Gauss pulse input by altering the input power and adding a section of dispersion compensation fiber (DCF). The same mechanisms are applied to a 2-channel wave divide multiplex system(WDM) as well. DCF is proved to be a good solution in both situations.
Measurement of nonlinear coefficient of optical fiber based on small chirped soliton transmission
Institute of Scientific and Technical Information of China (English)
无
2008-01-01
We measure the waveform and phase curves of short optical pulses before and after transmission over different lengths of fibers by use of the pulse analyzer with the frequency-resolved optical gating (FROG),and numerically simulate pulse evolution under the experimental conditions.The nonlinear coefficient of the fiber is given by comparing the experimental results with the numerical ones.Difference between the experiment and numerical simulation is analyzed.
Nonlinear absorption and transmission properties of Ge, Te and InAs using tuneable IR FEL
Energy Technology Data Exchange (ETDEWEB)
Amirmadhi, F.; Becker, K.; Brau, C.A. [Vanderbilt Univ., Nashville, TN (United States)
1995-12-31
Nonlinear absorption properties of Ge, Te and InAs are being investigated using the transmission of FEL optical pulses through these semiconductors (z-scan method). Wavelength, intensity and macropulse dependence are used to differentiate between two-photon and free-carrier absorption properties of these materials. Macropulse dependence is resolved by using a Pockles Cell to chop the 4-{mu}s macropulse down to 100 ns. Results of these experiments will be presented and discussed.
Performance characteristics and optimal analysis of a nonlinear diode refrigerator
Institute of Scientific and Technical Information of China (English)
Wang Xiu-Mei; He Ji-Zhou; Liang Hong-Ni
2011-01-01
This paper establishes a model of a nonlinear diode refrigerator consisting of two diodes switched in the opposite directions and located in two heat reservoirs with different temperatures. Based on the theory of thermal fluctuations, the expressions of the heat flux absorbed from the heat reservoirs are derived. After the heat leak between the two reservoirs is considered, the cooling rate and the coefficient of performance are obtained analytically. The influence of the heat leak and the temperature ratio on the performance characteristics of the refrigerator is analysed in detail.
Inductive intrinsic localized modes in a one-dimensional nonlinear electric transmission line
Sato, M.; Mukaide, T.; Nakaguchi, T.; Sievers, A. J.
2016-07-01
The experimental properties of intrinsic localized modes (ILMs) have long been compared with theoretical dynamical lattice models that make use of nonlinear onsite and/or nearest-neighbor intersite potentials. Here it is shown for a one-dimensional lumped electrical transmission line that a nonlinear inductive component in an otherwise linear parallel capacitor lattice makes possible a new kind of ILM outside the plane wave spectrum. To simplify the analysis, the nonlinear inductive current equations are transformed to flux transmission line equations with analog onsite hard potential nonlinearities. Approximate analytic results compare favorably with those obtained from a driven damped lattice model and with eigenvalue simulations. For this mono-element lattice, ILMs above the top of the plane wave spectrum are the result. We find that the current ILM is spatially compressed relative to the corresponding flux ILM. Finally, this study makes the connection between the dynamics of mass and force constant defects in the harmonic lattice and ILMs in a strongly anharmonic lattice.
Investigation on nonlinear thermo-acoustic characteristics of Rijke tube
Institute of Scientific and Technical Information of China (English)
DENG Kai; WU Yunfei; LI Hua; FANG Deming; ZHONG Yingjie
2011-01-01
Based on the energy conservation relationship, nonlinear thermo-acoustic effects of Rijke tube including instability range, saturation processes and higher harmonics modes were investigated. With coupling between the external flow and the inner space of a Rijke tube, the acoustic characteristics of self-excited oscillation were simulated. The experimental study was also carried out and the results were compared with those from simulation. The nonlinear factors which distort the acoustic waveform distortion were analyzed. From the results, it is seen that varying size of the nozzle outlet changes the acoustic impedance in the boundary, and leads to reduction of the nonlinear effects. The results show that the modes of self-excited oscillation could be influenced by the position of higher harmonics. In the large amplitude oscillation, the distortion of pressure wave within Rijke tube could be induced by the acoustic losses due to vortices on nozzle. It is found that the waveform distortion could be avoided by the shrinkage of nozzle.
New approach for identifying boundary characteristics using transmissibility
Joo, Kyung-Hoon; Min, Dongwoo; Kim, Jun-Gu; Kang, Yeon June
2017-04-01
A novel approach is proposed for identifying boundary properties as a response model using transmissibility. This approach differs from those proposed in previous studies dealing with frequency response functions (FRFs) for joint identification. Transmissibility includes only response data, unlike FRFs that include force measurements. The boundary properties can be estimated by comparing the characteristics of the components under the free condition and connected to boundary conditions. When analyzing the components assembled compactly in the system for setting the shaker or measuring the impact force exerted on the component correctly, the proposed method could reduce the errors caused by an incorrectly measured force. The derived equation is verified using a discrete multiple degrees of freedom system with single boundary and multiple boundary conditions and by application to a beam, which is the simplest continuous structural form to validate the feasibility of the theory. The transmissibility defined by the apparent mass matrix is used for verifying the derived equation for identifying the boundary properties in the discrete system. However, when applying the equation to practical cases, as is the purpose of this research, the transmissibility matrix should be defined using only the response data. For this purpose, the accelerance matrix is modified slightly to the response matrix using the input as a unit force. This transmissibility matrix composed of response data is used for validating the equation in a continuous system. Furthermore, the effects of measurement noise are also investigated to assess the robustness of the method for application under practical conditions. Consequently, the proposed method could show reliable results by properly extracting the boundary properties in both cases. In many practical cases, this research is expected to contribute toward identifying the boundary properties in a complex system more conveniently compared to the method
Nonlinear phase noise mitigation in phase-sensitive amplified transmission systems.
Olsson, Samuel L I; Karlsson, Magnus; Andrekson, Peter A
2015-05-04
We investigate the impact of in-line amplifier noise in transmission systems amplified by two-mode phase-sensitive amplifiers (PSAs) and present the first experimental demonstration of nonlinear phase noise (NLPN) mitigation in a modulation format independent PSA-amplified transmission system. The NLPN mitigation capability is attributed to the correlated noise on the signal and idler waves at the input of the transmission span. We study a single-span system with noise loading in the transmitter but the results are expected to be applicable also in multi-span systems. The experimental investigation is supported by numerical simulations showing excellent agreement with the experiments. In addition to demonstrating NLPN mitigation we also present a record high sensitivity receiver, enabled by low-noise PSA-amplification, requiring only 4.1 photons per bit to obtain a bit error ratio (BER) of 1 × 10(-3) with 10 GBd quadrature phase-shift keying (QPSK) data.
Modeling of Z-scan characteristics for one-dimensional nonlinear photonic bandgap materials.
Chen, Shuqi; Zang, Weiping; Schülzgen, Axel; Liu, Xin; Tian, Jianguo; Moloney, Jerome V; Peyghambarian, Nasser
2009-12-01
We propose a Z-scan theory for one-dimensional nonlinear photonic bandgap materials. The Z-scan characteristics for this material are analyzed. Results show that the Z-scan curves for photonic bandgap materials with nonlinear refraction are similar to those of uniform materials exhibiting both nonlinear refraction and nonlinear absorption simultaneously. Effects of nonlinear absorption on reflected and transmitted Z-scan results are also discussed.
Nguyen, Quan M.; Peleg, Avner; Tran, Thinh P.
2015-01-01
We develop a method for transmission stabilization and robust dynamic switching for colliding optical soliton sequences in broadband waveguide systems with nonlinear gain and loss. The method is based on employing hybrid waveguides, consisting of spans with linear gain and cubic loss, and spans with linear loss, cubic gain, and quintic loss. We show that the amplitude dynamics is described by a hybrid Lotka-Volterra (LV) model, and use the model to determine the physical parameter values required for enhanced transmission stabilization and switching. Numerical simulations with coupled nonlinear Schrödinger equations confirm the predictions of the LV model, and show complete suppression of radiative instability and pulse distortion. This enables stable transmission over distances larger by an order of magnitude compared with uniform waveguides with linear gain and cubic loss. Moreover, multiple on-off and off-on dynamic switching events are demonstrated over a wide range of soliton amplitudes, showing the superiority of hybrid waveguides compared with static switching in uniform waveguides.
Nonlinear optical characteristics of monolayer MoSe{sub 2}
Energy Technology Data Exchange (ETDEWEB)
Le, Chinh Tam; Ullah, Farman; Senthilkumar, Velusamy; Kim, Yong Soo [Department of Physics and Energy Harvest Storage Research Center, University of Ulsan (Korea, Republic of); Clark, Daniel J.; Jang, Joon I. [Department of Physics, Applied Physics and Astronomy, Binghamton University, Binghamton, NY (United States); Sim, Yumin; Seong, Maeng-Je [Department of Physics, Chung-Ang University, Seoul (Korea, Republic of); Chung, Koo-Hyun [School of Mechanical Engineering, University of Ulsan (Korea, Republic of); Park, Hyoyeol [Electronics, Communication and Semiconductor Applications Department, Ulsan College (Korea, Republic of)
2016-08-15
In this study, we utilized picosecond pulses from an Nd:YAG laser to investigate the nonlinear optical characteristics of monolayer MoSe{sub 2}. Two-step growth involving the selenization of pulsed-laser-deposited MoO{sub 3} film was employed to yield the MoSe{sub 2} monolayer on a SiO{sub 2}/Si substrate. Raman scattering, photoluminescence (PL) spectroscopy, and atomic force microscopy verified the high optical quality of the monolayer. The second-order susceptibility χ{sup (2)} was calculated to be ∝50 pm V{sup -1} at the second harmonic wavelength λ{sub SHG} ∝810 nm, which is near the optical gap of the monolayer. Interestingly, our wavelength-dependent second harmonic scan can identify the bound excitonic states including negatively charged excitons much more efficiently, compared with the PL method at room temperature. Additionally, the MoSe{sub 2} monolayer exhibits a strong laser-induced damage threshold ∝16 GW cm{sup -2} under picosecond-pulse excitation{sub .} Our findings suggest that monolayer MoSe{sub 2} can be considered as a promising candidate for high-power, thin-film-based nonlinear optical devices and applications. (copyright 2016 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Nonlinear optical imaging characteristics in rat tail tendon
Liu, N. R.; Zhang, X. Z.; Qiu, Y. S.; Chen, R.
2013-04-01
The aim of this study was to examine the characteristics of skeletal muscle fibers in tail tendons, explore the content of intrinsic components at different depths and ascertain the optimum excitation wavelength, which will help to establish a relationship between diagnosis and therapy and the tendon injury. A multiphoton microscopic imaging system was used to achieve the images and spectra via an imaging mode and a Lambda mode, respectively. This work demonstrates that the skeletal muscle fibers of the tail tendon are in good order. Second harmonic generation (SHG) and two-photon excited fluorescence (TPEF) signals originating from certain intrinsic components are varied with depth, and the SHG/TPEF intensity ratios are varied at different excitation wavelengths. Below 800 nm is the optimum for cell TPEF, while above 800 nm is the optimum for SHG. With the development of imaging techniques, a nonlinear optical imaging system will be helpful to represent the functional behaviors of tissue related to tendon injury.
EVALUATION OF NONLINEARITY EFFECTS ON PERFORMANCE OF DVB-H TRANSMISSION LINK
Directory of Open Access Journals (Sweden)
MD. SARWAR MORSHED
2010-08-01
Full Text Available Handheld devices of all kind have gained remarkable popularity in recent years. Choosing receiving end components for these handheld devices are critical. For example, if poorly suited and inexpensive amplifiers are chosen, then they tend to deteriorate signals. On the other hand, cheaper components are feasible for consumer product. This paper evaluates nonlinearity effects on transmission link serving Digital Video Broadcasting for Handhelds (DVB-H based on the results of software simulator. The system is tested in various receiving scenarios with presence of noise and received signal power varying from sensitivity level up to saturated nonlinear region. Neighboring DVB-H channel and close-by GSM-uplink are considered as distortion sources. The simulation results also analyze the behavior of the system in the presence of interfering signals with variouspower levels.
Simulation of "Tsunami Waves" Propagating along Non-Linear Transmission Lines
Directory of Open Access Journals (Sweden)
J. Valsa
2005-09-01
Full Text Available The paper compares three methods for computer simulation oftransients on transmission lines with losses and nonlinear behavior,namely distributed LC model, FDTD (Finite-Difference Time-Domainmethod, and a new and very effective Method of Slices. The losses areresponsible for attenuation and shape changes of the waves as functionof time and distance from the source. Special behavior of the line dueto voltage-dependent capacitance of the line is considered in detail.The non-linear nature of the line causes that the higher is the voltagethe higher is the velocity of propagation. Then, the waves tend to tiltover so that their top moves faster than their base. As a result"tsunami waves" are created on the line. Fundamental algorithms arepresented in Matlab language. Several typical situations are solved asan illustration of individual methods.
Man, Weining; Fardad, Shima; Zhang, Ze; Prakash, Jai; Lau, Michael; Zhang, Peng; Heinrich, Matthias; Christodoulides, Demetrios N; Chen, Zhigang
2013-11-22
We demonstrate a new class of synthetic colloidal suspensions capable of exhibiting negative polarizabilities, and observe for the first time robust propagation and enhanced transmission of self-trapped light over long distances that would have been otherwise impossible in conventional suspensions with positive polarizabilities. Such light penetration through the strong scattering environment is attributed to the interplay between optical forces and self-activated transparency effects while no thermal effect is involved. By judiciously mixing colloidal particles of both negative and positive polarizabilities, we show that the resulting nonlinear response of these systems can be fine-tuned. Our experimental observations are in agreement with theoretical analysis based on a thermodynamic model that takes into account particle-particle interactions. These results may open up new opportunities in developing soft-matter systems with engineered optical nonlinearities.
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
Numerical method to solve the problem related with theinteractive effect of dispersion (both chromatic dispersion and polarization mode dispersion) and nonlinearity on optical pulse transmission is present. Evolutions of pulses with various initial chirping and shape at bit-rate of 10 Gb/s are simulated and compared. Gaussian pulse with appropriate prechirping is propitious for high bit-rate transmission.
Sound radiation and transmission characteristics of finite composite panels
Patil, Avinash R.
2000-10-01
Laminated composite and sandwich composite panels are used widely in aircraft and space structures. Corrugated panels or bead-stiffened panels are used in building structures and automobiles. In these applications, the sound transmission through such panels is an important factor in their design. Their sound radiation characteristics are also important. These panels have been analyzed earlier mostly by assuming them to be of infinite size. But in real applications, only finite panels were used. The finite size of a panel affects its sound radiation below the critical frequency and consequently it also affects the resonant sound transmission through the panel. In the present work, such panels are analyzed considering their finite size. The analysis presented in this thesis is restricted to laminated composite panels, which have no coupling between bending and twisting. Corrugated panels with corrugations in only one direction were analyzed in this work. Sandwich composite panels, which have a symmetric configuration, were analyzed as well. Statistical Energy Analysis (SEA) was used for this purpose. The dispersion relations for laminated composite, sandwich composite and corrugated panels were studied. The phenomenon known as 'critical frequency band' was explained. Wavenumber diagrams were plotted for various frequencies. The mode count was obtained for the panels. A frequency averaged radiation efficiency was obtained from first principles. These results were used to calculate various SEA parameters. The transmission loss of the panels was predicted by using SEA and it is compared with the experimental results obtained by other researchers. The parametric analysis and optimization of a sandwich composite panel was carried out here. The analysis in this thesis is useful in the design of panels used for various engineering applications.
ENGINEERING CHARACTERISTICS AND ITS MECHANISM EXPLANATION OF VIBRATORY SYNCHRONIZATION TRANSMISSION
Institute of Scientific and Technical Information of China (English)
Xiong Wanli; Wen Bangchun; Duan Zhishan
2004-01-01
Vibratory synchronization transmission (VST) is a kind of special physical phenomenon in inertia vibra-tion mechanical systems.For an inertia vibration mechanical system driven by one pair of motors runs in step,even the power supply of one motor is cut off,the motor can continue to keep rotating state under the vibration exciting of the machine body driven by only one other motor.And its rotating frequency will be the same as that of the other one.The transient process of this wonderful physical phenomenon has not been described quantitatively according to current-existing mechanical models.On the basis of investigation of the engineering characteristics of VST,a mechanical and electrical coupling mathematical model of a two-shaft inertia vibration machine is established.With this model,the transient process of VST is recurred quantitatively and successfully,and a reasonable explana-tion is given.
Power-Voltage Characteristics of Power System with the Long Transmission Line
Directory of Open Access Journals (Sweden)
Prechanon Kumkratug
2012-01-01
Full Text Available Problem statement: Power- Voltage curve provides very important information for voltage stability analysis. The exact long transmission line model consists of the resistance and the reactance. The resistance causes in the active line loss. It is not easy task to achieve the power-voltage curve characteristics of power system with the exact long line model. Approach: This study applies the concept of the Newton-Raphson method to iteratively solve the nonlinear power flow equations. The Power-Voltage (P-V curve characteristic of the system without line loss and with line loss are plotted and compared on various cases. Results: It is found from the study that the resistance of the line obviously provides the negative effects on the voltage stability. The line loss causes in the decrement of the critical point. In addition, it is found that the leading power factor can increase the critical point of P-V curve. Conclusion: The exact long line model should be considered for voltage stability analysis of the system with the long transmission line.
Van Aert, S; Chen, J H; Van Dyck, D
2010-10-01
A widely used performance criterion in high-resolution transmission electron microscopy (HRTEM) is the information limit. It corresponds to the inverse of the maximum spatial object frequency that is linearly transmitted with sufficient intensity from the exit plane of the object to the image plane and is limited due to partial temporal coherence. In practice, the information limit is often measured from a diffractogram or from Young's fringes assuming a weak phase object scattering beyond the inverse of the information limit. However, for an aberration corrected electron microscope, with an information limit in the sub-angstrom range, weak phase objects are no longer applicable since they do not scatter sufficiently in this range. Therefore, one relies on more strongly scattering objects such as crystals of heavy atoms observed along a low index zone axis. In that case, dynamical scattering becomes important such that the non-linear and linear interaction may be equally important. The non-linear interaction may then set the experimental cut-off frequency observed in a diffractogram. The goal of this paper is to quantify both the linear and the non-linear information transfer in terms of closed form analytical expressions. Whereas the cut-off frequency set by the linear transfer can be directly related with the attainable resolution, information from the non-linear transfer can only be extracted using quantitative, model-based methods. In contrast to the historic definition of the information limit depending on microscope parameters only, the expressions derived in this paper explicitly incorporate their dependence on the structure parameters as well. In order to emphasize this dependence and to distinguish from the usual information limit, the expressions derived for the inverse cut-off frequencies will be referred to as the linear and non-linear structural information limit. The present findings confirm the well-known result that partial temporal coherence has
Goldsworthy, Ray L.; Greenberg, Julie E.
2004-12-01
The Speech Transmission Index (STI) is a physical metric that is well correlated with the intelligibility of speech degraded by additive noise and reverberation. The traditional STI uses modulated noise as a probe signal and is valid for assessing degradations that result from linear operations on the speech signal. Researchers have attempted to extend the STI to predict the intelligibility of nonlinearly processed speech by proposing variations that use speech as a probe signal. This work considers four previously proposed speech-based STI methods and four novel methods, studied under conditions of additive noise, reverberation, and two nonlinear operations (envelope thresholding and spectral subtraction). Analyzing intermediate metrics in the STI calculation reveals why some methods fail for nonlinear operations. Results indicate that none of the previously proposed methods is adequate for all of the conditions considered, while four proposed methods produce qualitatively reasonable results and warrant further study. The discussion considers the relevance of this work to predicting the intelligibility of cochlear-implant processed speech. .
Bias-field controlled phasing and power combination of gyromagnetic nonlinear transmission lines.
Reale, D V; Bragg, J-W B; Gonsalves, N R; Johnson, J M; Neuber, A A; Dickens, J C; Mankowski, J J
2014-05-01
Gyromagnetic Nonlinear Transmission Lines (NLTLs) generate microwaves through the damped gyromagnetic precession of the magnetic moments in ferrimagnetic material, and are thus utilized as compact, solid-state, frequency agile, high power microwave (HPM) sources. The output frequency of a NLTL can be adjusted by control of the externally applied bias field and incident voltage pulse without physical alteration to the structure of the device. This property provides a frequency tuning capability not seen in many conventional e-beam based HPM sources. The NLTLs developed and tested are mesoband sources capable of generating MW power levels in the L, S, and C bands of the microwave spectrum. For an individual NLTL the output power at a given frequency is determined by several factors including the intrinsic properties of the ferrimagnetic material and the transmission line structure. Hence, if higher power levels are to be achieved, it is necessary to combine the outputs of multiple NLTLs. This can be accomplished in free space using antennas or in a transmission line via a power combiner. Using a bias-field controlled delay, a transient, high voltage, coaxial, three port, power combiner was designed and tested. Experimental results are compared with the results of a transient COMSOL simulation to evaluate combiner performance.
Potential distribution and transmission characteristics in a curved quadrupole ion guide.
Zhou, Xiaoyu; Xiong, Caiqiao; Xu, Gaoping; Liu, Hao; Tang, Yin; Zhu, Zhiqiang; Chen, Rui; Qiao, Haoxue; Tseng, Yao-Hsin; Peng, Wen-Ping; Nie, Zongxiu; Chen, Yi
2011-02-01
The potential distribution in the curved quadrupole is exactly characterized by the Laplace equation, and an approximate solution to the Laplace equation is calculated. We represent the Laplace equation under the coordinates named minimal rotation frame (MRF) and derive an expression on the hexapole and octopole superposition. Our conclusion is in agreement with the results by the numerical (SIMION) method. Based on the Poincare-Lighthill-Kuo (PLK) method reported in our previous work, the nonlinear effects of ion motion are investigated in detail. The frequency shift of ion motion can be well eliminated by coupling the hexapole component with a positive octopole component, and the transmission efficiency of ions is found to decrease dramatically with the increase of the ionic kinetic energy in the z-direction. Furthermore, the transmission characteristics of ions are discussed with regards to the phase-space theory. The results show that the centrifugally introduced axis shift is mainly responsible for the ion losses. A modified direct current (dc) voltage supply pattern is hence proposed to compensate for this effect.
Vibration characteristics of single-stage planetary gear transmissions
Molina Vicuña,Cristián
2014-01-01
Condition monitoring based on vibration measurement and analysis of planetary gear transmissions has not provided the same good results observed in conventional fixed-shaft gear transmissions. One of the causes being the improper interpretation of the vibration spectrum. The structure of the lines present in the spectrum of the vibrations measured on a non-faulty planetary gear transmission, with a sensor mounted on the outer part of the ring gear, is strictly related to the geometry of the t...
A Suspended Stripline Frequency Tripler Using a Left-Handed Nonlinear Transmission Line
Directory of Open Access Journals (Sweden)
In Bok Kim
2015-01-01
Full Text Available A suspended stripline frequency tripler using a left-handed nonlinear transmission line (LH NLTL is presented. The proposed tripler using the LH NLTL is composed of a series of varactor diodes, shunt inductances, and a high-pass filter implemented with suspended stripline (SSL. An ultrawideband microstrip-to-suspended stripline transition is also utilized. The fabricated LH NLTL provides the minimum insertion loss of 1.7 dB and the maximum insertion loss of 4.7 dB for a wide frequency band from 2.6 to 18 GHz. As a tripler, the measured minimum third harmonic conversion loss is 15.3 dB at an input frequency of 2.4 GHz and typically 17 dB from 2 to 3.1 GHz.
Semrau, Daniel; Xu, Tianhua; Shevchenko, Nikita A; Paskov, Milen; Alvarado, Alex; Killey, Robert I; Bayvel, Polina
2017-01-01
Achievable information rates (AIRs) of wideband optical communication systems using a ∼40 nm (∼5 THz) erbium-doped fiber amplifier and ∼100 nm (∼12.5 THz) distributed Raman amplification are estimated based on a first-order perturbation analysis. The AIRs of each individual channel have been evaluated for DP-64QAM, DP-256QAM, and DP-1024QAM modulation formats. The impact of full-field nonlinear compensation (FF-NLC) and probabilistically shaped constellations using a Maxwell-Boltzmann distribution were studied and compared to electronic dispersion compensation. It has been found that a probabilistically shaped DP-1024QAM constellation, combined with FF-NLC, yields achievable information rates of ∼75 Tbit/s for the EDFA scheme and ∼223 Tbit/s for the Raman amplification scheme over a 2000 km standard single-mode fiber transmission.
Water environmental planning considering the influence of non-linear characteristics
Institute of Scientific and Technical Information of China (English)
ZENG Guang-ming; QIN Xiao-sheng; WANG Wei; HUANG Guo-he; LI Jian-bing; B. Statzner
2003-01-01
In practical water environmental planning, the influence of the non-linear characteristics on the benefit of environmental investment was seldom taken into consideration. This paper demonstrates that there exist a lot of non-linear behaviors in water environment by emphatically analyzing the influence of the non-linear characteristics of the economic scale, the meandering river and the model on water environmental planning, which will make a certain impact on the water environmental planning that sometimes cannot be neglected. This paper also preliminarily explores how to integrate the non-linear characteristics into water environmental planning. The results showed that compared with traditional methods, water environmental planning considering non-linear characteristics has its prevalence and it is necessary to develop the relevant planning theories and methods.
Optimisation of the Nonlinear Suspension Characteristics of a Light Commercial Vehicle
Directory of Open Access Journals (Sweden)
Dinçer Özcan
2013-01-01
Full Text Available The optimum functional characteristics of suspension components, namely, linear/nonlinear spring and nonlinear damper characteristic functions are determined using simple lumped parameter models. A quarter car model is used to represent the front independent suspension, and a half car model is used to represent the rear solid axle suspension of a light commercial vehicle. The functional shapes of the suspension characteristics used in the optimisation process are based on typical shapes supplied by a car manufacturer. The complexity of a nonlinear function optimisation problem is reduced by scaling it up or down from the aforementioned shape in the optimisation process. The nonlinear optimised suspension characteristics are first obtained using lower complexity lumped parameter models. Then, the performance of the optimised suspension units are verified using the higher fidelity and more realistic Carmaker model. An interactive software module is developed to ease the nonlinear suspension optimisation process using the Matlab Graphical User Interface tool.
Pan, Shuokai; Elliott, Stephen J; Teal, Paul D; Lineton, Ben
2015-06-01
Nonlinear models of the cochlea are best implemented in the time domain, but their computational demands usually limit the duration of the simulations that can reasonably be performed. This letter presents a modified state space method and its application to an example nonlinear one-dimensional transmission-line cochlear model. The sparsity pattern of the individual matrices for this alternative formulation allows the use of significantly faster numerical algorithms. Combined with a more efficient implementation of the saturating nonlinearity, the computational speed of this modified state space method is more than 40 times faster than that of the original formulation.
Directory of Open Access Journals (Sweden)
Abd El-Naser A. Mohammed
2010-09-01
Full Text Available In the present paper, the problem amplification techniques of ultra dense wavelength division multiplexing (UDWDM in nonlinear optical networks are investigated through five transmission techniques. The impact of tailoring of chirped pulses of different temporal waveforms is investigated in a normal dispersion fiber. The set of multiplexed signals are tailored in a different a subset to assure approximately the same output level of power to hold the signal-to-noise ratio at the same level. Moreover, three different transmission techniques, namely, soliton propagation, maximum time division multiplexing (MTDM and ìShannonî capacity, are employed where successive section of alternating dispersion are used as a technique to manage the dispersion. Distributed ìRamanî amplifiers as well as Erbium doped fiber amplifier are engaged to maximize the repeater spacing. We have succeeded to multiplex 2400 (UDWDM channels in the optical range 1.45 1.65 µm with channel spacing ranging from 0.3 up to 0.6 nm where each channel has its own characteristic parameters of loss, dispersion, and amplification. The channels are divided into sub-groups ( each of 4, 5, 6, 7,Ö.,24 where the technique of space division multiplexing (SDM is applied. The multispan effects of ìKerrî nonlinearity and amplifier noise on ìShannonî channel capacity of dispersion-free nonlinear fiber is considered as a ceiling value for the sake of comparison. The case of soliton with modified Raman amplification via parametric gain also is investigated. Each link has special chemical structure, optical signals power, and optical Raman pumping. The cable contains {4, 5, 6, 7,Ö. , 24} links in SDM. It has been shown that the modified Raman gain yields higher effects on the variable under consideration if compared with the conventional Raman gain. The number of links is in positive correlations with the set of effects {Repeater spacing, Soliton product, MTDM product}. In general
Bilal, Syed Muhammad; Goroshko, Kseniia; Louchet, Hadrien; Koltchanov, Igor; Richter, André
2017-07-01
In this work we investigate different nonlinearities compensation and mitigation techniques for an unrepeated Raman-amplified link over 420 km of ultra-low loss (ULL) optical fiber. For such long links (over 400 km) fiber nonlinearities become very significant as high forward pump power is needed to ensure sufficient optical-signal-to-noise-ratio (OSNR) to acquire a bit-error-rate (BER) not exceeding the forward-error-correction (FEC) threshold. Such nonlinearities will significantly limit the performance. Through numerical simulations, we show successful net 200 Gb/s single carrier and 1 Tb/s superchannel transmission using PM-QPSK and symbol-rate-optimization (SRO). First we implement single carrier 200 G transmission either using 28 Gbaud PM-16QAM or 56 Gbaud PM-QPSK. Nonlinearities are compensated by either using digital-back-propagation (DBP) or phase-conjugated twin waves (PCTWs). We compare the performance of DBP and PCTWs based single carrier 28 Gbaud PM-16QAM, at the same transmission distance and capacity, with single carrier PM-QPSK and find that PM-QPSK does not require any nonlinearity compensation to give better performance than 28 Gbaud PM-16QAM. Following this result, we show a successful unrepeated transmission of net 1 Tb/s PM-QPSK Nyquist-spaced superchannel with an intra-superchannel net spectral efficiency (SE) of ∼3.6 b/s/Hz, over 420 km of Raman amplified ULL fiber without using any nonlinearity compensation. To improve the performance of this superchannel we implement nonlinearity mitigation scheme based on SRO. We investigate 5 × 56 Gbaud, 10 × 28 Gbaud, 20 × 14 Gbaud and 40 × 7 Gbaud PM-QPSK channels and found that the best performance is shown by 20 × 14 Gbaud superchannel. For PM-16QAM, successful transmission is only possible either using DBP or PCTWs based transmission link. DBP has a very high computational complexity whereas PCTWs halves the overall link spectral efficiency. Even then both schemes do not outperform PM-QPSK for
Windhorst, U; Kokkoroyiannis, T; Laouris, Y; Meyer-Lohmann, J
1994-03-01
Spinal recurrent inhibition via Renshaw cells and proprioceptive feedback via skeletal muscle and muscle spindle afferents have been hypothesized to constitute a compound feedback system [Windhorst (1989) Afferent Control of Posture and Locomotion; Windhorst (1993) Robots and Biological Systems--Towards a New Bionics]. To assess their detailed functions, it is necessary to know their dynamic characteristics. Previously we have extensively described the properties of signal transmission from motor axons to Renshaw cells using random motor axon stimulation and data analysis methods based thereupon. Using the same methods, we here compare these properties, in the cat, with those between motor axons and group Ia muscle spindle afferents in terms of frequency responses and nonlinear features. The frequency responses depend on the mean rate (carrier rate) of activation of motor axons and on the strength of coupling between motor units and spindles. In general, they are those of a second-order low-pass system with a cut-off at fairly low frequencies. This contrasts with the dynamics of motor axon-Renshaw cell couplings which are those of a much broader band-pass with its peak in the range of c. 2-15 Hz [Christakos (1987) Neuroscience 23, 613-623]. The second-order non-linearities in motor unit-muscle spindle signal lines are much more diverse than those in motor axon-Renshaw cell couplings. Although the average strength of response declines with mean stimulus rate in both subsystems, there is no systematic relationship between the amount of non-linearity and the average response in the former, whilst there is in the latter. The qualitative appearance of motor unit-muscle spindle non-linearities was complicated as was the average response to motor unit twitches. Thus, whilst Renshaw cells appear to dynamically reflect motor output rather faithfully, muscle spindles seem to signal local muscle fibre length changes and their dynamics. This would be consistent with the
Institute of Scientific and Technical Information of China (English)
Feng Liu; Qing Ye; Aiping Luo; Jianrong Qiu; Congshan Zhu; Ronghui Qu; Zujie Fang
2005-01-01
The nonlinear switching characteristics of fused fiber directional couplers were studied experimentally. By using femtosecond laser pulses with pulse width of 100 fs and wavelength of about 1550 nm from a system of Ti:sapphire laser and optical parametric amplifier (OPA), the nonlinear switching properties of a null coupler and a 100% coupler were measured. The experimental results were coincident with the simulations based on nonlinear propagation equations in fiber by using super-mode theory. Nonlinear loss in fiber was also measured to get the injected power at the coupler. After deducting the nonlinear loss and input efficiency, the nonlinear switching critical peak powers for a 100% and a null fused couplers were calculated to be 9410 and 9440 W, respectively. The nonlinear loss parameter PN in an expression of αNL = αP/PN was obtained to be PN = 0.23 W.
van den Berg, Stéphanie Martine
2009-01-01
Modeling both genetic and cultural transmission in parent-offspring data in the presence of phenotypic assortment requires the imposition of nonlinear constraints. This article reports a simulation study that determined how well the structural equation modeling software package Mx and the
Berg, van den Stephanie M.
2009-01-01
Modeling both genetic and cultural transmission in parent-offspring data in the presence of phenotypic assortment requires the imposition of nonlinear constraints. This article reports a simulation study that determined how well the structural equation modeling software package Mx and the Bayesian-o
Gou, Pengqi; Wang, Kaihui; Qin, Chaoyi; Yu, Jianjun
2017-03-01
We experimentally demonstrate a 16-ary quadrature amplitude modulation (16QAM) DFT-spread optical orthogonal frequency division multiplexing (OFDM) transmission system utilizing a cost-effective directly modulated laser (DML) and direct detection. For 20-Gbaud 16QAM-OFDM signal, with the aid of nonlinear equalization (NLE) algorithm, we respectively provide 6.2-dB and 5.2-dB receiver sensitivity improvement under the hard-decision forward-error-correction (HD-FEC) threshold of 3.8×10-3 for the back-to-back (BTB) case and after transmission over 10-km standard single mode fiber (SSMF) case, related to only adopt post-equalization scheme. To our knowledge, this is the first time to use dynamic nonlinear equalizer (NLE) based on the summation of the square of the difference between samples in one IM/DD OFDM system with DML to mitigate nonlinear distortion.
Kasai, Seiya; Tadokoro, Yukihiro; Ichiki, Akihisa
2013-12-01
We design nonlinear functions for the transmission of a small signal with non-Gaussian noise and perform experiments to characterize their responses. Using statistical design theory [A. Ichiki and Y. Tadokoro, Phys. Rev. E 87, 012124 (2013), 10.1103/PhysRevE.87.012124], a static nonlinear function is estimated from the probability density function of the given noise in order to maximize the signal-to-noise ratio of the output. Using an electronic system that implements the optimized nonlinear function, we confirm the recovery of a small signal from a signal with non-Gaussian noise. In our experiment, the non-Gaussian noise is a mixture of Gaussian noises. A similar technique is also applied to the optimization of the threshold value of the function. We find that, for non-Gaussian noise, the response of the optimized nonlinear systems is better than that of the linear system.
Nonlinear Vibration Analysis of Helical Face-Gear Transmission System with Multi-Factor
Directory of Open Access Journals (Sweden)
Liu Bo
2016-01-01
Full Text Available A systematic analysis of the dynamics of a helical face-gear system with 8 degree of freedom is performed in this study under complex excitation. The nonlinear dynamic system is solved by the Runge-Kutta method. The bifurcation and dynamic load characteristics of the system is identified from a series of diagrams. The effect of multi-factor on bifurcation diagrams is also analysed. The results real that with the increase of dimensionless frequency, the system undergoes the process of periodic, chaotic and periodic motions. The amplitude of the dynamic load gradually increases in a certain range and begins to decrease at a certain value. A higher mesh damping coefficient or a higher input torque or a lower gear backlash can reduce the vibration or eliminate chaotic responses.
High power microwave beam steering based on gyromagnetic nonlinear transmission lines
Energy Technology Data Exchange (ETDEWEB)
Romanchenko, I. V., E-mail: riv@lfe.hcei.tsc.ru; Rostov, V. V.; Gunin, A. V.; Konev, V. Yu. [Institute of high current electronics SB RAS, Akademichesky 2/3, 634055, Tomsk (Russian Federation)
2015-06-07
We demonstrate electronically controlled beam steering by high power RF pulses produced by two gyromagnetic nonlinear transmission lines (NLTLs) connected to a one high voltage driver. Each NLTL is capable of producing several ns RF pulses with peak power from 50 to 700 MW (6% standard deviation) at frequencies from 0.5 to 1.7 GHz (1% standard deviation) with 100 Hz repetition rate. Using a helix antenna allows irradiating of RF pulses with almost circular polarization and 350 MW maximum peak power, which corresponds to 350 kV effective potential of radiation. At the installation of two identical channels, we demonstrate the possibility of beam steering within ±15° in the horizontal plane by coherent RF pulses with circular polarization at 1.0 GHz center frequency. Fourfold increase in the power flux density for in-phase irradiation of RF pulses is confirmed by comparison with one-channel operation.
Solid-State Radio Frequency Plasma Heating Using a Nonlinear Transmission Line
Miller, Kenneth; Ziemba, Timothy; Prager, James; Slobodov, Ilia
2015-11-01
Radio Frequency heating systems are rarely used by the small-scale validation platform experiments due to the high cost and complexity of these systems, which typically require high power gyrotrons or klystrons, associated power supplies, waveguides and vacuum systems. The cost and complexity of these systems can potentially be reduced with a nonlinear transmission line (NLTL) based system. In the past, NLTLs have lacked a high voltage driver that could produce long duration high voltage pulses with fast rise times at high pulse repetition frequency. Eagle Harbor Technologies, Inc. (EHT) has created new high voltage nanosecond pulser, which combined with NLTL technology will produce a low-cost, fully solid-state architecture for the generation of the RF frequencies (0.5 to 10 GHz) and peak power levels (~ 10 MW) necessary for plasma heating and diagnostic systems for the validation platform experiments within the fusion science community. The proposed system does not require the use of vacuum tube technology, is inherently lower cost, and is more robust than traditional high power RF heating schemes. Design details and initial bench testing results for the new RF system will be presented. This work is supported under DOE Grant # DE-SC0013747.
Directory of Open Access Journals (Sweden)
Tadeusz Dziubak
2014-12-01
Full Text Available [b]Abstract[/b]. Potentials effects of pressure drop-flow characteristics of ATF filter on the hydraulic pumps are discussed. Draft device to investigations pressure drop-flow characteristics of ATF filter used in automatic transmissions constructed based on SAE J2312 standard is presented. Method of investigation pressure drop-flow characteristics of ATF filter used in automatic transmission is presented. The results of investigation pressure drop-flow characteristics Δp = f(QV of two types ATF filter (metal mesh and filter cloth in two technical conditions (at the beginning of the operation and after are presented and analyzed.[b]Keywords[/b]: AT — automatic transmissions, ATF — automatic transmission fluid, ATF filter, pressure drop-flow characteristic
Zhang, Huayong; Huang, Tousheng; Dai, Liming
2015-05-01
Predator-prey interaction widely exists in nature and the research on predator-prey systems is an important field in ecology. The nonlinear dynamic characteristics of a seasonally perturbed predator-prey system are studied in this research. To study the nonlinear characteristics affected by a wide variety of system parameters, the PR approach is employed and periodic, quasiperiodic, chaotic behaviors and the behaviors between period and quasiperiod are found in the system. Periodic-quasiperiodic-chaotic region diagrams are generated for analyzing the global characteristics of the predator-prey system with desired ranges of system parameters. The ecological significances of the dynamical characteristics are discussed and compared with the theoretical research results existing in the literature. The approach of this research demonstrates effectiveness and efficiency of PR method in analyzing the complex dynamical characteristics of nonlinear ecological systems.
van den Berg, Stéphanie M
2009-01-01
Modeling both genetic and cultural transmission in parent-offspring data in the presence of phenotypic assortment requires the imposition of nonlinear constraints. This article reports a simulation study that determined how well the structural equation modeling software package Mx and the Bayesian-oriented BUGS software package can handle such nonlinear constraints under various conditions. Results generally showed good and comparable results for Mx and BUGS, although BUGS was much slower than Mx. However, since BUGS uses Markov-chain Monte Carlo estimation it could be used for parent-offspring models with non-normal data and/or item-response theory models.
Characteristics of Watermelon Mosaic Virus Transmission Occurring in Korean Ginseng
Directory of Open Access Journals (Sweden)
Seung-Kook Choi
2014-09-01
Full Text Available Korean ginseng (Panax ginseng is the most popular herb for medical purpose in Korea. Recently, viral diseases from Korean ginseng showing various degrees of severe mottling, variegation and mosaic symptoms have caused quantity losses of Korean ginseng in a large number of farms. Watermelon mosaic virus (named WMVgin was identified as a causal agent for the disease of Korean ginseng. Interestingly, WMV-gin failed to infect both Korean ginseng plant and susceptible host species including cucurbitaceous plants by mechanical inoculation. However, WMV-gin could successfully infect Korean ginseng by transmission of two aphid species (Myzus persicae and Aphis gossypii. It is likely that transmission of WMV-gin was done by both the aphid species during feeding behavior of the two aphid species on Korean ginseng, though the aphids dislike feeding in Korea ginseng. Similarly, a strain of WMV (WMV-wm isolated from watermelon was transmitted successfully to Korean ginseng plant by the two aphid species, but not by mechanical inoculations. Transmission assays using M. persicae and A. gossypii clearly showed both WMV-gin and WMV-wm were not transmitted from infected Korean ginseng plant to cucurbit species that are good host species for WMV. These results suggest WMV disease occurring in Korean ginseng plant can be controlled by ecological approaches.
Energy Technology Data Exchange (ETDEWEB)
Klofai, Yerima [Department of Physics, Higher Teacher Training College, University of Maroua, PO Box 46 Maroua (Cameroon); Essimbi, B Z [Department of Physics, Faculty of Science, University of Yaounde 1, PO Box 812 Yaounde (Cameroon); Jaeger, D, E-mail: bessimb@yahoo.fr [ZHO, Optoelectronik, Universitaet Duisburg-Essen, D-47048 Duisburg (Germany)
2011-10-15
Pulse propagation on high-frequency dissipative nonlinear transmission lines (NLTLs)/resonant tunneling diode line cascaded maps is investigated for long-distance propagation of short pulses. Applying perturbative analysis, we show that the dynamics of each line is reduced to an expanded Korteweg-de Vries-Burgers equation. Moreover, it is found by computer experiments that the soliton developed in NLTLs experiences an exponential amplitude decay on the one hand and an exponential amplitude growth on the other. As a result, the behavior of a pulse in special electrical networks made of concatenated pieces of lines is closely similar to the transmission of information in optical/electrical communication systems.
Wang, Zuo-Cai; Xin, Yu; Ren, Wei-Xin
2016-08-01
This paper proposes a new nonlinear joint model updating method for shear type structures based on the instantaneous characteristics of the decomposed structural dynamic responses. To obtain an accurate representation of a nonlinear system's dynamics, the nonlinear joint model is described as the nonlinear spring element with bilinear stiffness. The instantaneous frequencies and amplitudes of the decomposed mono-component are first extracted by the analytical mode decomposition (AMD) method. Then, an objective function based on the residuals of the instantaneous frequencies and amplitudes between the experimental structure and the nonlinear model is created for the nonlinear joint model updating. The optimal values of the nonlinear joint model parameters are obtained by minimizing the objective function using the simulated annealing global optimization method. To validate the effectiveness of the proposed method, a single-story shear type structure subjected to earthquake and harmonic excitations is simulated as a numerical example. Then, a beam structure with multiple local nonlinear elements subjected to earthquake excitation is also simulated. The nonlinear beam structure is updated based on the global and local model using the proposed method. The results show that the proposed local nonlinear model updating method is more effective for structures with multiple local nonlinear elements. Finally, the proposed method is verified by the shake table test of a real high voltage switch structure. The accuracy of the proposed method is quantified both in numerical and experimental applications using the defined error indices. Both the numerical and experimental results have shown that the proposed method can effectively update the nonlinear joint model.
Research on nonlinear characteristics of strata collapse because of the multi-frequency mining
Institute of Scientific and Technical Information of China (English)
YANG Fan; HU Zhen-qi; YANG Lun; MA Feng-hai
2008-01-01
Based on the complexity of mine stratum and coupling of the multi-frequency for the damage of mine stratum, using the method of on-site inspection and mathematical statistics, the regulation and nonlinear characteristics of strata collapse in mine stratum's multi-frequency mining were put forward and systemically studied. Study result shows that the influence of multi-frequency mining in mine stratum has the feature of multi-frequency incontinuity, multi-characteristic and multi-type nonlinear collapse, strata collapse activation turned worse, presenting an accumulation effect of multi-frequency mining for the strata damage. With the example of multi-frequency mining in the mine, the real characteristics of strata collapse by multi-frequency mining and nonlinear characteristics of accumulative response damage were analyzed. Research achievements about the surface recover and controlling of strata collapse by the multi-frequency mining have instruction meaning.
Lazo, Edmundo; Garrido, Alejandro; Neira, Félix
2016-11-01
This study investigates the localization properties of dual electric transmission lines with non-linear capacitances. The VC,n voltage across each capacitor is selected as a non-linear function of the electric charge qn, i.e., VC,n = qn(1/Cn -ɛn|qn|2) where Cn is the linear part of the capacitance and ɛn the amplitude of the non-linear term. We follow a binary distribution of values of ɛn, according to the Thue-Morse m-tupling sequence. The localization behavior of this non-linear case indicates that the case m = 2 does not belong to the m ≥ 3, family because when m changes from m = 2 to m = 3, the number of extended states diminishes dramatically. This proves the topological difference of the m = 2 and m = 3 families. However, by increasing m values, localization behavior of the m-tupling family resembles that of the m = 2, case because the system begins to regain its extended states. The exact same result was obtained recently in the study of linear direct transmission lines with m-tupling distribution of inductances. Consequently, we state that the localization behavior of the m-tupling family as a function of the m value is independent of both the linear and the non-linear system under study, but independent of the kind of transmission line (dual or direct). This is curious behavior of the m-tupling family and thus deserves more scholarly attention.
Institute of Scientific and Technical Information of China (English)
无
2003-01-01
Based on the electromagnetic field theory, the optical signal transmission characteristics in input/output waveguides, slab waveguides and arrayed waveguides of the arrayed waveguide grating (AWG) multi/demultiplexer are analyzed. The relationship between the physical parameters such as geometry sizes and relative refractive index in AWG multi/demultiplexer and the optical signal transmission characteristics are discussed. This theoretical study can be used for optimizing the design and improving the performance of the AWG multi/demultiplexer.
Nonlinear Characteristics of an Intense Laser Pulse Propagating in Partially Stripped Plasmas
Institute of Scientific and Technical Information of China (English)
HU Qiang-Lin; LIU Shi-Bing; CHEN Tao; JIANG Yi-Jian
2005-01-01
The nonlinear optic characteristics of an intense laser pulse propagating in partially stripped plasmas are investigated analytically. The phase and group velocity of the laser pulse propagation as well as the three general expressions governing the nonlinear optic behavior, based on the photon number conservation, are obtained by considering the partially stripped plasma as a nonlinear optic medium. The numerical result shows that the presence of the bound electrons in partially stripped plasma can significantly change the propagating property of the intense laser pulse.
NONLINEAR BUCKLING CHARACTERISTIC OF GRADED MULTIWEB STRUCTURE OF HETEROGENEOUS MATERIALS
Institute of Scientific and Technical Information of China (English)
LI Yong; ZHANG Zhi-min
2005-01-01
The graded multiweb structure of heterogeneous anisotropic materials, which makes full use of the continuous, gradual and changing physical mechanical performance of material properties, has a widespread application in aeroplane aerofoil structure and automobile lightweight structure. On the basis of laminate buckling theory,the equivalent rigidity method is adopted to establish the corresponding constitutive relation and the non-linear buckling governing equation for the graded multiweb structure. In finding the solution, the critical load of buckling under different complicated boundary conditions together with combined loads were obtained and testification of the experimental analysis shows that the calculation results can satisfy the requirements of engineering design in a satisfactory way. Results obtained from the research say that: graded materials can reduce the concentrated stress on the interface in an effective way and weaken the effect of initial defect in materials and thereby improve the strength and toughness of materials.
Institute of Scientific and Technical Information of China (English)
YANG Ning; WU Zhigang; YANG Chao
2011-01-01
The flutter characteristics of an actuator-fin system are investigated with structural nonlinearity and dynamic stiffness of the electric motor.The component mode substitution method is used to establish the nonlinear governing equations in time domain and frequency domain based on the fundamental dynamic equations of the electric motor and decelerator.The existing describing function method and a proposed iterative method are used to obtain the flutter characteristics containing preload freeplay nonlinearity when the control command is zero.A comparison between the results of frequency domain and those of time domain is studied.Simulations are carried out when the control command is not zero and further analysis is conducted when the freeplay angle is changed.The results show that structural nonlinearity and dynamic stiffness have a significant influence on the flutter characteristics.Limit cycle oscillations(LCOs)are observed within linear flutter boundary.The response of the actuator-fin system is related to the initial disturbance.In the nonlinear condition,the amplitude of the control command has an influence on the flutter characteristics.
ANALYSIS OF TRANSMISSION CHARACTERISTICS OF COSINE GEAR DRIVE
Institute of Scientific and Technical Information of China (English)
WANG Jian; LUO Shanming; CHEN Lifeng; CHEN Lei; HU Huarong
2008-01-01
Based on the mathematical model of a novel cosine gear drive, a few characteristics, such as the contact ratio, the sliding coefficient, and the contact and bending stresses, of this drive are analyzed. A comparison study of these characteristics with the involute gear drive is also carried out. The influences of design parameters including the number of teeth and the pressure angle on the contact and bending stresses are studied. The following conclusions are achieved: the contact ratio of the cosine gear drive is about 1.2 to 1.3, which is reduced by about 20% in comparison with that of the involute gear drive. The sliding coefficient of the cosine gear drive is smaller than that of the involute gear drive. The contact and bending stresses of the cosine gear drive are lower than those of the involute gear drive. The contact and bending stresses decrease with the growth of the number of teeth and the pressure angle.
DEFF Research Database (Denmark)
Da Ros, Francesco; Sackey, I.; Jazayerifar, M.
2015-01-01
Kerr nonlinearity compensation by optical phase conjugation is demonstrated in a WDM PDM 16-QAM system. Improved received signal quality is reported for both dispersion-compensated and dispersion-uncompensated transmission and a comparison with digital backpropagation is provided....
Transmission characteristics of high-power 589-nm laser beam in photonic crystal fiber
Ito, Meguru; Hayano, Yutaka; Saito, Norihito; Akagawa, Kazuyuki; Kato, Mayumi; Saito, Yoshihiko; Takazawa, Akira; Takami, Hideki; Iye, Masanori; Wada, Satoshi; Colley, Stephen A.; Dinkins, Matthew C.; Eldred, Michael; Golota, Taras I.; Guyon, Olivier; Hattori, Masayuki; Oya, Shin; Watanabe, Makoto
2006-06-01
We are developing Laser Guide Star Adaptive Optics (LGSAO) system for Subaru Telescope at Hawaii, Mauna Kea. We achieved an all-solid-state 589.159 nm laser in sum-frequency generation. Output power at 589.159 nm reached 4W in quasi-continuous-wave operation. To relay the laser beam from laser location to laser launching telescope, we used an optical fiber because the optical fiber relay is more flexible and easier than mirror train. However, nonlinear scattering effect, especially stimulated Raman scattering (SRS) and stimulated Brillouin scattering (SBS), will happen when the inputted laser power increases, i.e., intensity at the fiber core exceed each threshold. In order to raise the threshold levels of each nonlinear scattering, we adopt photonic crystal fiber (PCF). Because the PCF can be made larger core than usual step index fiber (SIF), one can reduce the intensity in the core. We inputted the high power laser into the PCF whose mode field diameter (MFD) is 14 μm and the SIF whose MFD is 5 μm, and measured the transmission characteristics of them. In the case of the SIF, the SRS was happen when we inputted 2 W. On the other hand, the SRS and the SBS were not induced in the PCF even for an input power of 4 W. We also investigated polarization of the laser beam transmitting through the PCF. Because of the fact that the backscattering efficiency of exciting the sodium layer with a narrowband laser is dependent on the polarization state of the incident beam, we tried to control the polarization of the laser beam transmitted the PCF. We constructed the system which can control the polarization of input laser and measure the output polarization. The PCF showed to be able to assume as a double refraction optical device, and we found that the output polarization is controllable by injecting beam with appropriate polarization through the PCF. However, the Laser Guide Star made by the beam passed through the PCF had same brightness as the state of the polarization.
Institute of Scientific and Technical Information of China (English)
Qian-ying Chen; Jing Gao; Kun Dai; Huan Pang; Jia-zhuang Xu; Jian-hua Tang; Zhong-ming Li
2013-01-01
Current-voltage electrical behavior of in situ microfibrillar carbon black (CB)/poly(ethylene terephthalate)(PET)/polyethylene (PE) (m-CB/PET/PE) composites with various CB concentrations at ambient temperatures was studied under a direct-current electric field.The current-voltage (Ⅰ-Ⅴ) curves exhibited nonlinearity beyond a critical value of voltage.The dynamic random resistor network (DRRN) model was adopted to semi-qualitatively explain the nonlinear conduction behavior of m-CB/PET/PE composites.Macroscopic nonlinearity originated from the interracial interactions between CB/PET micro fibrils and additional conduction channels.Combined with the special conductive networks,an illustration was proposed to interpret the nonlinear Ⅰ-Ⅴ characteristics by a field emission or tunneling mechanism between CB particles in the CB/PET microfibers intersections.
Characteristics of the Main Journal Bearings of an Engine Based on Non-linear Dynamics
Institute of Scientific and Technical Information of China (English)
NI Guangjian; ZHANG Junhong; CHENG Xiaoming
2009-01-01
Many simple nonlinear main journal bearing models have been studied theoretically, but the connection to existing engineering system has not been equally investigated. The consideration of the characteristics of engine main journal bearings may provide a prediction of the bearing load and lubrication. Due to the strong non-linear features in bearing lubrication procedure, it is difficult to predict those characteristics. A non-linear dynamic model is described for analyzing the characteristics of engine main journal bearings. Components such as crankshaft, main journals and con rods are found by applying the finite element method. Non-linear spring/dampers are introduced to imitate the constraint and supporting functions provided by the main bearing and oil film. The engine gas pressure is imposed as excitation on the model via the engine piston, con rod, etc. The bearing reaction force is calculated over one engine cycle, and meanwhile, the oil film thickness and pressure distribution are obtained based on Reynolds differential equation. It can be found that the maximum bearing reaction force always occurs when the maximum cylinder pressure arises in the cylinder adjacent to that bearing. The simulated minimum oil film thickness, which is 3 μm, demonstrates the reliability of the main journal bearings. This non-linear dynamic analysis may save computing efforts of engine main bearing design and also is of good precision and close connection to actual engine main journal bearing conditions.
Fu, Libi; Song, Weiguo; Lo, Siuming
2017-01-01
Emergencies involved in mass events are related to a variety of factors and processes. An important factor is the transmission of information on danger that has an influence on nonlinear crowd dynamics during the process of crowd dispersion. Due to much uncertainty in this process, there is an urgent need to propose a method to investigate the influence. In this paper, a novel fuzzy-theory-based method is presented to study crowd dynamics under the influence of information transmission. Fuzzy functions and rules are designed for the ambiguous description of human states. Reasonable inference is employed to decide the output values of decision making such as pedestrian movement speed and directions. Through simulation under four-way pedestrian situations, good crowd dispersion phenomena are achieved. Simulation results under different conditions demonstrate that information transmission cannot always induce successful crowd dispersion in all situations. This depends on whether decision strategies in response to information on danger are unified and effective, especially in dense crowds. Results also suggest that an increase in drift strength at low density and the percentage of pedestrians, who choose one of the furthest unoccupied Von Neumann neighbors from the dangerous source as the drift direction at high density, is helpful in crowd dispersion. Compared with previous work, our comprehensive study improves an in-depth understanding of nonlinear crowd dynamics under the effect of information on danger.
Non-Linear Noise Contributions in Highly Dispersive Optical Transmission Systems
Matera, Francesco
2016-01-01
This article reports an analytical investigation, confirmed by numerical simulations, about the non-linear noise contribution in single-channel systems adopting generic modulation-detection formats in long links with both managed and unmanaged dispersion compensation and its impact in system performance. This noise contribution is expressed in terms of a pulse non-linear interaction length and permits a simple calculation of the Q-factor. Results point out the dependence of this non-linear noise on the number of amplifiers spans, N, according to the adopted chromatic dispersion compensation scheme, the modulation-detection format, and the signal baud rate. It is also shown how the effects of polarization multiplexing can be taken into account and how this single-channel non-linear noise contribution can be used in a wavelength-division multiplexing (WDM) environment.
Institute of Scientific and Technical Information of China (English)
无
1999-01-01
Making use of disk targets composed of several peculiar materials (foam Au, foam C8H8)and hohlraum with a special structure, experiments have been done at"Xing Guang - II" laser facility,which study the characteristics of hot electrons and therelated nonlinear processes such as StimulatedRaman Scattering (SRS), Two Plasma Decay (TPD), StimulatedBrillouin Scattering (SBS), etc.
Kengne, E; Lakhssassi, A
2015-03-01
We consider a lossless one-dimensional nonlinear discrete bi-inductance electrical transmission line made of N identical unit cells. When lattice effects are considered, we use the reductive perturbation method in the semidiscrete limit to show that the dynamics of modulated waves can be modeled by the classical nonlinear Schrödinger (CNLS) equation, which describes the modulational instability and the propagation of bright and dark solitons on a continuous-wave background. Our theoretical analysis based on the CNLS equation predicts either two or four frequency regions with different behavior concerning the modulational instability of a plane wave. With the help of the analytical solutions of the CNLS equation, we investigate analytically the effects of the linear capacitance CS on the dynamics of matter-wave solitons in the network. Our results reveal that the linear parameter CS can be used to manipulate the motion of bright, dark, and kink soliton in the network.
Modeling of the wave transmission properties of large arteries using nonlinear elastic tubes.
Pythoud, F; Stergiopulos, N; Meister, J J
1994-11-01
We propose a new, simple way of constructing elastic tubes which can be used to model the nonlinear elastic properties of large arteries. The tube models are constructed from a silicon elastomer (Sylgard 184, Dow Corning), which exhibits a nonlinear behavior with increased stiffness at high strains. Tests conducted on different tube models showed that, with the proper choice of geometric parameters, the elastic properties, in terms of area-pressure relation and compliance, can be similar to that of real arteries.
Non-linear characteristics of the endolymph-cupula nystagmus system
Mccormack, Percival D.
1988-01-01
The way a human can detect angular acceleration forces by means of the semicircular canals in the ears is discussed. The anatomy of the canals and the characteristics of the canal fluids are described. The physical implications of variation in cupula stiffness with angular acceleration are examined by analyzing cross-coupled angular acceleration and modeling mathematically the cupula-endolymph system. The system transfer function is obtained and the nonlinear characteristics of the endolymph-cupula-nystagmus system are discussed.
Jing, Xingjian
2015-01-01
This book is a systematic summary of some new advances in the area of nonlinear analysis and design in the frequency domain, focusing on the application oriented theory and methods based on the GFRF concept, which is mainly done by the author in the past 8 years. The main results are formulated uniformly with a parametric characteristic approach, which provides a convenient and novel insight into nonlinear influence on system output response in terms of characteristic parameters and thus facilitate nonlinear analysis and design in the frequency domain. The book starts with a brief introduction to the background of nonlinear analysis in the frequency domain, followed by recursive algorithms for computation of GFRFs for different parametric models, and nonlinear output frequency properties. Thereafter the parametric characteristic analysis method is introduced, which leads to the new understanding and formulation of the GFRFs, and nonlinear characteristic output spectrum (nCOS) and the nCOS based analysis a...
Nonlinear dynamic characteristics of piles embedded in rock%嵌岩桩非线性动力学特性
Institute of Scientific and Technical Information of China (English)
胡春林; 程昌钧; 胡胜刚
2007-01-01
The nonlinear dynamic characteristics of a pile embedded in a rock were investigated.Suppose that both the materials of the pile and the soil around the pile obey nonlinear elastic and linear viscoelastic constitutive relations.The nonfinear partial differential equation governing the dynamm characteristics of the pile was first derived.The Galerkin method Wasusedto simplify the equation and to obtain a nonlinear ordinary differential equation.The methods in nonlinear dynamics were employed to solve the simplified dynamical system,and the time-path curves,phase-trajectory diagrams,power spectrum,the dynamic characteristics of the system were also considered in detail.
Evaluation of Ultrasonic Nonlinear Characteristics in Heat-Treated Aluminum Alloy (Al-Mg-Si-Cu
Directory of Open Access Journals (Sweden)
JongBeom Kim
2013-01-01
Full Text Available The nonlinear ultrasonic technique has been known to be more sensitive to minute variation of elastic properties in material than the conventional linear ultrasonic method. In this study, the ultrasonic nonlinear characteristics in the heat-treated aluminum alloy (Al-Mg-Si-Cu have been evaluated. For this, the specimens were heat treated for various heating period up to 50 hours at three different heating temperatures: 250°C, 300°C, and 350°C. The ultrasonic nonlinear characteristics of each specimen were evaluated by measuring the ultrasonic nonlinear parameter β from the amplitudes of fundamental and second harmonic frequency components in the transmitted ultrasonic wave. After the ultrasonic test, tensile strengths and elongations were obtained by the tensile test to compare with the parameter β. The heating time showing a peak in the parameter β was identical to that showing critical change in the tensile strength and elongation, and such peak appeared at the earlier heating time in the higher heating temperature. These results suggest that the ultrasonic nonlinear parameter β can be used for monitoring the variations in elastic properties of aluminum alloys according to the heat treatment.
Institute of Scientific and Technical Information of China (English)
杨祥林; 徐铭; 蔡炬
2003-01-01
The coupled nonlinear Schrodinger equations for dispersion-managed soliton (DMS) with the impact of thepolarization mode dispersion (PMD) are constructed, and a PMD-suppression approach of DMS is proposed for the first time. Then, based on variational method, the analytical equations of the DMS transmission system within-line optical filter control are obtained. Finally, in order to investigate the validity of the equations, we presentan application sample for practical systems with in-line filter control. The results verify that the control is quiteeffective and valid.
Khairuzzaman, Md; Zhang, Chao; Igarashi, Koji; Katoh, Kazuhiro; Kikuchi, Kazuro
2010-03-01
We describe a successful introduction of maximum-likelihood-sequence estimation (MLSE) into digital coherent receivers together with finite-impulse response (FIR) filters in order to equalize both linear and nonlinear fiber impairments. The MLSE equalizer based on the Viterbi algorithm is implemented in the offline digital signal processing (DSP) core. We transmit 20-Gbit/s quadrature phase-shift keying (QPSK) signals through a 200-km-long standard single-mode fiber. The bit-error rate performance shows that the MLSE equalizer outperforms the conventional adaptive FIR filter, especially when nonlinear impairments are predominant.
Voltage adjusting characteristics in terahertz transmission through Fabry-Pérot-based metamaterials
Directory of Open Access Journals (Sweden)
Jun Luo
2015-10-01
Full Text Available Metallic electric split-ring resonators (SRRs with featured size in micrometer scale, which are connected by thin metal wires, are patterned to form a periodically distributed planar array. The arrayed metallic SRRs are fabricated on an n-doped gallium arsenide (n-GaAs layer grown directly over a semi-insulating gallium arsenide (SI-GaAs wafer. The patterned metal microstructures and n-GaAs layer construct a Schottky diode, which can support an external voltage applied to modify the device properties. The developed architectures present typical functional metamaterial characters, and thus is proposed to reveal voltage adjusting characteristics in the transmission of terahertz waves at normal incidence. We also demonstrate the terahertz transmission characteristics of the voltage controlled Fabry-Pérot-based metamaterial device, which is composed of arrayed metallic SRRs. To date, many metamaterials developed in earlier works have been used to regulate the transmission amplitude or phase at specific frequencies in terahertz wavelength range, which are mainly dominated by the inductance-capacitance (LC resonance mechanism. However, in our work, the external voltage controlled metamaterial device is developed, and the extraordinary transmission regulation characteristics based on both the Fabry-Pérot (FP resonance and relatively weak surface plasmon polariton (SPP resonance in 0.025-1.5 THz range, are presented. Our research therefore shows a potential application of the dual-mode-resonance-based metamaterial for improving terahertz transmission regulation.
ANALYSIS OF AN SI EPIDEMIC MODEL WITH NONLINEAR TRANSMISSION AND STAGE STRUCTURE
Institute of Scientific and Technical Information of China (English)
陆忠华; 高淑京; 陈兰荪
2003-01-01
A disease transmission model of SI type with stage structure is formulated.The stability of disease free equilibrium, the existence and uniqueness of an endemic equi-librium, the existence of a global attractor are investigated.
Institute of Scientific and Technical Information of China (English)
DONG Zheng; HUANG Da-gui; ZHANG De-yin
2006-01-01
Ultraviolet (UV) fire detector is used to detect fire according to the ultraviolet radiation of the flame. High detecting sensitivity of the sensor requires high ultraviolet transmission property of the detecting window. In this paper, high performance JGS-1 (type name of glass) ultraviolet quartz glass is used as the sensor detecting window material and the ultraviolet transmission characteristics of the glass is studied. A new method with the smart fire detecting module to test the ultraviolet transmission parameter of quartz glass is demonstrated. The comparison results of UV spectrometer and this new method manifest that JGS-1 quartz glass has good ultraviolet transmission character and the new test method with fire detecting module is direct and feasible.
Word, Daniel P; Cummings, Derek A T; Burke, Donald S; Iamsirithaworn, Sopon; Laird, Carl D
2012-08-07
Mathematical models can enhance our understanding of childhood infectious disease dynamics, but these models depend on appropriate parameter values that are often unknown and must be estimated from disease case data. In this paper, we develop a framework for efficient estimation of childhood infectious disease models with seasonal transmission parameters using continuous differential equations containing model and measurement noise. The problem is formulated using the simultaneous approach where all state variables are discretized, and the discretized differential equations are included as constraints, giving a large-scale algebraic nonlinear programming problem that is solved using a nonlinear primal-dual interior-point solver. The technique is demonstrated using measles case data from three different locations having different school holiday schedules, and our estimates of the seasonality of the transmission parameter show strong correlation to school term holidays. Our approach gives dramatic efficiency gains, showing a 40-400-fold reduction in solution time over other published methods. While our approach has an increased susceptibility to bias over techniques that integrate over the entire unknown state-space, a detailed simulation study shows no evidence of bias. Furthermore, the computational efficiency of our approach allows for investigation of a large model space compared with more computationally intensive approaches.
DEFF Research Database (Denmark)
Zibar, Darko; Winther, Ole; Franceschi, Niccolo
2012-01-01
In this paper, we show numerically and experimentally that expectation maximization (EM) algorithm is a powerful tool in combating system impairments such as fibre nonlinearities, inphase and quadrature (I/Q) modulator imperfections and laser linewidth. The EM algorithm is an iterative algorithm...
Nonlinear dynamic characteristics of SMA intravascular stent under radial stochastic loads.
Zhu, Zhiwen; Zhang, Qingxin; Xu, Jia
2014-01-01
Nonlinear dynamic characteristics of shape memory alloy (SMA) intravascular stent under radial stochastic loads were studied in this paper. Von de Pol item was improved to interpret the hysteretic phenomena of SMA, and the nonlinear dynamic model of SMA intravascular stent under radial stochastic loads was developed. The conditions of stochastic stability of the system were obtained in singular boundary theory. The steady-state probability density function of the dynamic response of the system was given, and the stochastic Hopf bifurcation characteristics of the system were analyzed. Theoretical analysis and numerical simulation show that the stability of the trivial solution varies with bifurcation parameters, and stochastic Hopf bifurcation appears in the process, which can cause stent fracture or loss. The results of this paper are helpful to application of SMA intravascular stent in biomedical engineering fields.
Detailed discussion of the optimum baud rate of nonlinearity in WDM transmission
Wang, Wanli; Qiao, Yaojun; Yang, Lin
2017-01-01
Different numbers of sub-channels correspond to different baud rates per sub-channel when the total baud rate is fixed. The optimum baud rate of nonlinearity in WDM systems is investigated in this paper. We find that the phase matching effect produces an optimum baud rate of nonlinearity, which is related to the chromatic dispersion accumulation of a single span. Then other factors that influence the optimum baud rate are analyzed. By mathematical derivation and simulation verification, larger number of spans and larger spectrum gap between sub-channels both make the optimum value decrease. We also find that different modulation formats barely change the optimum baud rate if other system settings are the same and all sub-channels have the same modulation format.
Non-linear processes in thin titanium nitride transmission lines for parametric amplification
Vissers, Michael; Gao, Jiansong; Chaudhuri, Suptarshi; Bockstiegel, Clint; Sandberg, Martin; Pappas, David P.
2013-03-01
Nitride superconductors, such as titanium nitride and niobium titanium nitride, are a non-linear, low dissipation medium at microwave frequencies. The lossless nonlinearity may be probed and utilized. Important applications include generation of higher harmonics, e.g. 3f, and a microwave version of the optical paramagnetic amplifier, i.e. the degenerate-pump case of four-photon mixing (FPM). An amplifier based on these principles should allow for very wide bandwidth, low noise (quantum limited) and high dynamic range devices. These measurements are performed via a single layer, 3 meter long TiN spiral and measured at temperatures below 100 mK. Initial results of the design, fabrication, testing, and impedance optimization of a titanium nitride based parametric amplifier are presented.
DEFF Research Database (Denmark)
Porto da Silva, Edson
Digital signal processing (DSP) has become one of the main enabling technologies for the physical layer of coherent optical communication networks. The DSP subsystems are used to implement several functionalities in the digital domain, from synchronization to channel equalization. Flexibility...... nonlinearity compensation, (II) spectral shaping, and (III) adaptive equalization. For (I), original contributions are presented to the study of the nonlinearity compensation (NLC) with digital backpropagation (DBP). Numerical and experimental performance investigations are shown for different application...... scenarios. Concerning (II), it is demonstrated how optical and electrical (digital) pulse shaping can be allied to improve the spectral confinement of a particular class of optical time-division multiplexing (OTDM) signals that can be used as a building block for fast signaling single-carrier transceivers...
Energy Technology Data Exchange (ETDEWEB)
Reena Mary, A P; Anantharaman, M R [Department of Physics, Cochin University of Science and Technology, Cochin 682 022 (India); Suchand Sandeep, C S; Philip, Reji [Light and Matter Physics Group, Raman Research Institute, Sadashivanagar, Bangalore-560080 (India); Narayanan, T N; Moloney, Padraig; Ajayan, P M, E-mail: reji@rri.res.in, E-mail: mraiyer@yahoo.com [Department of Mechanical Engineering and Materials Science, Rice University, Houston, TX-77005 (United States)
2011-09-16
Oxide free stable metallic nanofluids have the potential for various applications such as in thermal management and inkjet printing apart from being a candidate system for fundamental studies. A stable suspension of nickel nanoparticles of {approx} 5 nm size has been realized by a modified two-step synthesis route. Structural characterization by x-ray diffraction and transmission electron microscopy shows that the nanoparticles are metallic and are phase pure. The nanoparticles exhibited superparamagnetic properties. The magneto-optical transmission properties of the nickel nanofluid (Ni-F) were investigated by linear optical dichroism measurements. The magnetic field dependent light transmission studies exhibited a polarization dependent optical absorption, known as optical dichroism, indicating that the nanoparticles suspended in the fluid are non-interacting and superparamagnetic in nature. The nonlinear optical limiting properties of Ni-F under high input optical fluence were then analyzed by an open aperture z-scan technique. The Ni-F exhibits a saturable absorption at moderate laser intensities while effective two-photon absorption is evident at higher intensities. The Ni-F appears to be a unique material for various optical devices such as field modulated gratings and optical switches which can be controlled by an external magnetic field.
Li, Jingcheng; Waynert, Joseph A; Whisner, Bruce G
A medium frequency (MF) communication system operating in an underground coal mine couples its signals to a long conductor, which acts as an MF transmission line (TL) in a tunnel to permit communications among transceivers along the line. The TL is generally the longest signal path for the system, and its propagation characteristics will have a major impact on the performance of the MF communication system. In this study, the propagation characteristics of three types of MF TLs in two layouts-on the roof and on the floor of a coal mine tunnel-were obtained in an effort to understand the propagation characteristics of different TLs in different locations. The study confirmed a low MF signal loss on all of these TLs. The study also found that the TLs in different layouts had substantially different propagation characteristics. The propagation characteristics of these different TLs in different layouts are presented in the paper.
Institute of Scientific and Technical Information of China (English)
WANG Zefeng; HU Yongming
2009-01-01
Perforated panel structures have a wide potential in underwater applications. However, up to now there has been little related research. The acoustic impedance of an underwater perforated panel is obtained based on the theories for air perforated panel sound absorption.In this paper sound transmission characteristics of underwater perforated panel structures are theoretically analyzed by the transfer matrix method. A formula for normal incidence sound transmission coefficients is given. The main factors that have effects on the acoustic transmission coefficient are analyzed by numerical simulations. The perforated panel structures made by ourselves are tested in a standing-wave tube by the four-sensor transfer-function method.The experimental results are well in accord with the results obtained by the numerical method,which proves that the theoretical analysis is correct. This paper has provided theoretical and experimental bases for the design of underwater perforated panel structures.
Nonreciprocal transmission in a nonlinear photonic-crystal Fano structure with broken symmetry
DEFF Research Database (Denmark)
Yu, Yi; Chen, Yaohui; Hu, Hao;
2015-01-01
Nanostructures that feature nonreciprocal light trans- mission are highly desirable building blocks for realizing photonic integrated circuits. Here, a simple and ultracompact photonic-crystal structure, where a waveguide is coupled to a single nanocavity, is proposed and experimentally demon- st...... tunability. The nonlinearity of the device relies on ultrafast carrier dynamics, rather than the thermal effects usually considered, allowing the demonstration of nonreciprocal operation at a bit-rate of 10 Gbit s − 1 with a low energy consumption of 4.5 fJ bit − 1...
An adaptive linearizer for 16-QAM transmission over non-linear satellite channels
Shanmugan, K. Sam; Ruggles, M. J.
An adaptive nonlinear equalization scheme that consists of a predistorter located at the transmitting earth station and a linear equalizer at the receiving earth station is described. Algorithms for automatically adjusting the predistorter and the linear equalizer are presented. The effectiveness of the scheme is evaluated using simulations. It is shown that the scheme improves the performance of a 16-queued access memory system operating over a typical satellite channel by minimizing degradations in the signal as it is transmitted over a band-limited satellite channel.
Aguilar-López, Ricardo; Martínez-Guerra, Rafael; Perez-Pinacho, Claudia A.
2014-06-01
The main issue of this work is related with the design of a class of nonlinear observer in order to synchronize chaotic dynamical systems in a master-slave scheme, considering different initial conditions. The oscillator of Chen is proposed as a benchmark model and a bounded-type observer is proposed to reach synchronicity between both two chaotic systems. The proposed observer contains a proportional and sigmoid form of a bounded function of the synchronization error in order to provide asymptotic synchronization with a satisfactory performance. Some numerical simulations were carrying out in order to show the operation of the proposed methodology, with possible applications to secure data communications issues.
Abbasnia,Arash; Ghiasi,Mahmoud
2014-01-01
Fully nonlinear wave interaction with a fixed breakwater is investigated in a numerical wave tank (NWT). The potential theory and high-order boundary element method are used to solve the boundary value problem. Time domain simulation by a mixed Eulerian-Lagrangian (MEL) formulation and high-order boundary integral method based on non uniform rational B-spline (NURBS) formulation is employed to solve the equations. At each time step, Laplace equation is solved in Eulerian frame and fully non-l...
Nakae, T.; Ryu, T.; Matsuzaki, K.; Rosbi, S.; Sueoka, A.; Takikawa, Y.; Ooi, Y.
2016-09-01
In the torque converter, the damper of the lock-up clutch is used to effectively absorb the torsional vibration. The damper is designed using a piecewise-linear spring with three stiffness stages. However, a nonlinear vibration, referred to as a subharmonic vibration of order 1/2, occurred around the switching point in the piecewise-linear restoring torque characteristics because of the nonlinearity. In the present study, we analyze vibration reduction for subharmonic vibration. The model used herein includes the torque converter, the gear train, and the differential gear. The damper is modeled by a nonlinear rotational spring of the piecewise-linear spring. We focus on the optimum design of the spring characteristics of the damper in order to suppress the subharmonic vibration. A piecewise-linear spring with five stiffness stages is proposed, and the effect of the distance between switching points on the subharmonic vibration is investigated. The results of our analysis indicate that the subharmonic vibration can be suppressed by designing a damper with five stiffness stages to have a small spring constant ratio between the neighboring springs. The distances between switching points must be designed to be large enough that the amplitude of the main frequency component of the systems does not reach the neighboring switching point.
Global Dynamic Characteristic of Nonlinear Torsional Vibration System under Harmonically Excitation
Institute of Scientific and Technical Information of China (English)
SHI Peiming; LIU Bin; HOU Dongxiao
2009-01-01
Torsional vibration generally causes serious instability and damage problems in many rotating machinery parts. The global dynamic characteristic of nonlinear torsional vibration system with nonlinear rigidity and nonlinear friction force is investigated. On the basis of the generalized dissipation Lagrange's equation, the dynamics equation of nonlinear torsional vibration system is deduced. The bifurcation and chaotic motion in the system subjected to an external harmonic excitation is studied by theoretical analysis and numerical simulation. The stability of unperturbed system is analyzed by using the stability theory of equilibrium positions of Hamiltonian systems. The criterion of existence of chaos phenomena under a periodic perturbation is given by means of Melnikov's method. It is shown that the existence of homoclinic and heteroclinic orbits in the unperturbed system implies chaos arising from breaking of homoclinic or heteroclinic orbits under perturbation. The validity of the result is checked numerically. Periodic doubling bifurcation route to chaos, quasi-periodic route to chaos, intermittency route to chaos are found to occur due to the amplitude varying in some range. The evolution of system dynamic responses is demonstrated in detail by Poincare maps and bifurcation diagrams when the system undergoes a sequence of periodic doubling or quasi-periodic bifurcations to chaos. The conclusion can provide reference for deeply researching the dynamic behavior of mechanical drive systems.
One size does not fit all. A non-linear analysis of European monetary transmission
Giulio Cifarelli; Giovanna Paladino
2014-01-01
This paper investigates the interest rate pass-through in eight European countries analyzing their short-run and long-run monetary transmission mechanisms. We investigate the relationship between the Euribor and the long-run interest rate on loans to non-financial corporations and allow for a mark-up which can be affected by country specific funding conditions and/or stochastic structural breaks. We detect significant differences across countries. Cointegration between the Euribor and the lon...
Directory of Open Access Journals (Sweden)
G. P. Pavlos
1999-01-01
Full Text Available A long AE index time series is used as a crucial magnetospheric quantity in order to study the underlying dynainics. For this purpose we utilize methods of nonlinear and chaotic analysis of time series. Two basic components of this analysis are the reconstruction of the experimental tiine series state space trajectory of the underlying process and the statistical testing of an null hypothesis. The null hypothesis against which the experimental time series are tested is that the observed AE index signal is generated by a linear stochastic signal possibly perturbed by a static nonlinear distortion. As dis ' ' ating statistics we use geometrical characteristics of the reconstructed state space (Part I, which is the work of this paper and dynamical characteristics (Part II, which is the work a separate paper, and "nonlinear" surrogate data, generated by two different techniques which can mimic the original (AE index signal. lie null hypothesis is tested for geometrical characteristics which are the dimension of the reconstructed trajectory and some new geometrical parameters introduced in this work for the efficient discrimination between the nonlinear stochastic surrogate data and the AE index. Finally, the estimated geometric characteristics of the magnetospheric AE index present new evidence about the nonlinear and low dimensional character of the underlying magnetospheric dynamics for the AE index.
Numerical modeling of DPSK pressure signals and their transmission characteristics in mud channels
Institute of Scientific and Technical Information of China (English)
Shen Yue; Su Yinao; Li Gensheng; Li Lin; Tian Shouceng
2009-01-01
A numerical model and transmission characteristic analysis of DPSK (differential phase shift keying) pressure signals in mud channels is introduced. With the control logic analysis of the rotary valve mud telemetry, a logical control signal is built from a Gate function sequence according to the binary symbols of transmitted data and a phase-shift function is obtained by integrating the logical control signal. A mathematical model of the DPSK pressure signal is built based on principles of communications by modulating carrier phase with the phase-shift function and a numerical simulation of the pressure wave is implemented with the mathematical model by MATLAB programming. Considering drillpipe pressure and drilling fluid temperature profile along drillpipes, the drillpipe of a vertical well is divided into a number of sections. With water-based drilling fluids, the impacts of travel distance, carrier frequency, drillpipe size, and drilling fluids on the signal transmission were studied by signal transmission characteristic analysis for all the sections. Numerical calculation results indicate that the influences of the viscosity of drilling fluids and volume fraction of gas in drilling fluids on the DPSK signal transmission are more notable than the others and the signal will distort in waveform with differential attenuations of the signal frequent component.
Characteristic of wireless power transmission S-Parameter for a superconductor coil
Energy Technology Data Exchange (ETDEWEB)
Jeong, In Sung; Jung, Byung Ik; Choi, Hyo Sang [Chosun University, Gwangju (Korea, Republic of)
2015-03-15
Many studies are being conducted to implement wireless charging, for example, for cellular phones or electronic tooth brushes, via wireless power transmission technique. However, the magnetic induction method had a very short transmission distance. To solve this problem, the team of Professor Marin Soljacic proposed a magnetic resonance system that used two resonance coils with the same resonance frequency. It had an approximately 40% efficiency at a 2m distance. The system improved the low efficiency and short distance problems of the existing systems. So it could also widen the application range of wireless power transmission. Many studies on the subject are underway. In this paper, the superconductor coil was used to improve the efficiency of magnetic resonance wireless power transmission. The resonance wireless power transmission system had a source coil, a load coil, and resonance coils (a transmitter and a receiver). The efficiency and distance depended on the characteristics of the transmitter and receiver coils that had the same resonance frequency. Therefore, two resonance coils were fabricated by superconductors. The current density of the superconductor was higher than that of the normal conductor coil. Accordingly, it had a high quality-factor and improved efficiency.
Sound transmission loss characteristics of sandwich panels with a truss lattice core.
Ehsan Moosavimehr, S; Srikantha Phani, A
2017-04-01
Sandwich panels are extensively used in constructional, naval, and aerospace structures due to the high stiffness and strength-to-weight ratios. In contrast, the sound transmission properties are adversely influenced by the low effective mass. Phase velocity matching of structural waves propagating within the panel and the incident pressure waves from the fluid medium leads to coincidence effects resulting in reduced impedance and high sound transmission. Truss-like lattice cores with porous microarchitecture and reduced inter panel connectivity offer the potential to satisfy the conflicting structural and vibroacoustic response requirements. This study combines Bloch-wave analysis and the finite element method to understand wave propagation and hence sound transmission in sandwich panels with a truss lattice core. Three dimensional coupled fluid-structure finite element simulations are conducted to compare the performance of a representative set of lattice core topologies. Potential advantages of sandwich structures with a lattice core are identified. The significance of partial band gaps is evident in the sound transmission loss characteristics of the panels studied. This work demonstrates that, even without optimization, significant enhancements in sound transmission loss performance can be achieved in truss lattice core sandwich panels compared to a traditional sandwich panel employing a honeycomb core under constant mass constraint.
Programmable Solution for Solving Non-linearity Characteristics of Smart Sensor Applications
Directory of Open Access Journals (Sweden)
S. Khan
2007-10-01
Full Text Available This paper presents a simple but programmable technique to solve the problem of non-linear characteristics of sensors used in more sensitive applications. The nonlinearity of the output response becomes a very sensitive issue in cases where a proportional increase in the physical quantity fails to bring about a proportional increase in the signal measured. The nonlinearity is addressed by using the interpolation method on the characteristics of a given sensor, approximating it to a set of tangent lines, the tangent points of which are recognized in the code of the processor by IF-THEN code. The method suggested here eliminates the use of external circuits for interfacing, and eases the programming burden on the processor at the cost of proportionally reduced memory requirements. The mathematically worked out results are compared with the simulation and experimental results for an IR sensor selected for the purpose and used for level measurement. This work will be of paramount importance and significance in applications where the controlled signal is required to follow the input signal precisely particularly in sensitive robotic applications.
One modified method of characteristics used to analyze the multiconductor transmission lines
Institute of Scientific and Technical Information of China (English)
Fu Jiwei; Hou Chaozhen; Dou Lihua
2006-01-01
To solve the coupling effect of multiconductor transmission lines excited by external electromagnetic wave, the modified method of characteristics is proposed. The modified method of characteristics which can compute the terminal induced voltages excited by the external electromagnetic wave when the terminal networks or interconnection networks contain the dynamic elements is introduced. The simulation results indicate that the modified method can analyze the terminal induced voltages when the terminal networks or the interconnection networks contain the dynamic elements excited by the external electromagnetic wave. And the results are compared with the results acquired by FDTD method, the two results are completely same. So one effective modified method is implemented to compute the transmission lines.
Institute of Scientific and Technical Information of China (English)
WEI Daoping; JIANG Zhong'ao; ZHAO Yucheng; JIAN Shuisheng
2000-01-01
Based on mode-coupled theory, a Bragg grating assisted mismatched fiber coupler is analyzed theoretically. At the same time, a detailed numerical analysis on transmission characteristics of the coupler is carried out when it considers the arcs of two fibers in the coupling region of the coupler or not, and the optimized design on the Bragg grating assisted mismatched fiber coupler for wavelength-division multiplexing/ demultiplexing is proposed.
Wet Permeability and Moisture Vapor Transmission Characteristics of Soybean Knitted Fabrics
Institute of Scientific and Technical Information of China (English)
王其; 冯勋伟
2001-01-01
Wet permeability of fibrous assembly is mainly influenced by the properties of liquid and the configurations of the fiber which consist of diameter of fiber, twist angle and fiber alignment in a yarn. It can be seen from experimental results that the knitted fabric made of soybean (SB) fiber has goodproperties both in wet permeability and vapor transmission so that the knitting technology and fabric characteristics can be improved.
On the non-linear attachment characteristics of blood to bacterial cellulose/kaolin biomaterials.
Véliz, Diosángeles Soto; Alam, Catharina; Toivola, Diana M; Toivakka, Martti; Alam, Parvez
2014-04-01
In this communication, we report a non-linear variation in the strength of blood attachment to bacterial cellulose/kaolin biomaterials as the fractions of bacterial cellulose to kaolin are increased. The changes observed for attachment strength are elucidated following both experimental and numerical investigations on both the biomaterial and the blood-biomaterial interface. Our research reveals that the non-linear strength of attachment of blood is related to topographical characteristics on the surface of the biomaterial, the maleability of the biomaterial and the intermolecular strength of attraction between clotted blood proteins (fibrinogen) with the cellulose/kaolin components of the biomaterial. Copyright © 2014 Elsevier B.V. All rights reserved.
Measurement of nonlinear coefficient and phase matching characteristics of AgGaS sub 2
Energy Technology Data Exchange (ETDEWEB)
Canarelli, P.; Benko, Z.; Hielscher, A.H.; Curl, R.F.; Tittle, F.K. (Dept. of Electrical and Computer Engineering, Rice Quantum Inst., Rice Univ., Houston, TX (US))
1992-01-01
This paper reports on a nonlinear optical characteristics of AgGaS{sub 2} that were investigated by measuring visible parametric fluorescence with a pump wavelength of 600 nm. A value of d{sub 36}(AgGaS{sub 2}) = 31 {plus minus} 5 10{sup {minus}12} m/V for the nonlinear coefficient was determined. The temperature dependence of phase matching up to 100{degrees}C was studied. A significant temperature effect, although much smaller than the LiNbO{sub 3}, was found and results in a change in the infrared difference frequency generated of {approximately}0.6 cm{sup {minus}1} {center dot} {degrees}C{sup {minus}1}.
Simulation of non-linear rf losses derived from characteristic Nb topography
Energy Technology Data Exchange (ETDEWEB)
Reece, Charles E. [JLAB; Xu, Chen; Kelley, Michael [W& M. JLAB
2013-09-01
A simplified model has been developed to simulate non-linear RF losses on Nb surfaces exclusively due to topographical enhancement of surface magnetic fields. If local sharp edges are small enough, at locations where local surface fields exceed Hc, small volumes of material may become normal conducting without thermal leading to quench. These small volumes of normal material yield increases in the effective surface resistance of the Nb. Using topographic data from typical BCP?d and EP?d fine grain niobium surfaces, we have simulated field-dependent losses and found that when extrapolated to resulting cavity performance, these losses correspond well to characteristic BCP/EP high field Q0 performance differences for fine grain Nb. We describe the structure of the model, its limitations, and the effects of this type of non-linear loss contribution on SRF cavities.
Energy Technology Data Exchange (ETDEWEB)
Tsysar, S. A., E-mail: sergey@acs366.phys.msu.ru; Nikolaeva, A. V.; Khokhlova, V. A.; Yuldashev, P. V. [Physics Faculty, Moscow State University, Leninskie Gory, Moscow 119991 (Russian Federation); Svet, V. D. [Andreyev Acoustics Institute, 4, Shvernik Street, Moscow 117036 (Russian Federation); Sapozhnikov, O. A. [Physics Faculty, Moscow State University, Leninskie Gory, Moscow 119991 (Russian Federation); Center for Industrial and Medical Ultrasound, Applied Physics Laboratory, University of Washington, 1013 NE 40th Street, Seattle, WA 98105 (United States)
2015-10-28
In the paper the use of receiving and radiating system, which allows to determine the parameters of bone by nonlinear pulse-echo technique and to image of brain structures through the skull bones, was proposed. Accuracy of the skull bone characterization is due to higher measured harmonic and is significantly better than in linear case. In the experimental part focused piezoelectric transducer with diameter 100 mm, focal distance 100 mm, the frequency of 1.092 MHz was used. It was shown that skull bone profiling can be performed with the use of 3rd harmonic since 1st harmonic can be used for visualization of the underlying objects. The use of wideband systems for both skull profiling and brain visualization is restricted by skull attenuation and resulting low effective sensitivity.
Gusev, A. I.; Pedos, M. S.; Rukin, S. N.; Timoshenkov, S. P.
2017-07-01
In this work, experiments were made in which gyromagnetic nonlinear transmission line (NLTL) operates as a peak power amplifier of the input pulse. At such an operating regime, the duration of the input pulse is close to the period of generated oscillations, and the main part of the input pulse energy is transmitted only to the first peak of the oscillations. Power amplification is achieved due to the voltage amplitude of the first peak across the NLTL output exceeding the voltage amplitude of the input pulse. In the experiments, the input pulse with an amplitude of 500 kV and a half-height pulse duration of 7 ns is applied to the NLTL with a natural oscillation frequency of ˜300 MHz. At the output of the NLTL in 40 Ω coaxial transmission line, the pulse amplitude is increased to 740 kV and the pulse duration is reduced to ˜2 ns, which correspond to power amplification of the input pulse from ˜6 to ˜13 GW. As a source of input pulses, a solid-state semiconductor opening switch generator was used, which allowed carrying out experiments at pulse repetition frequency up to 1 kHz in the burst mode of operation.
Nonlinear Dynamic Characteristic Analysis of the Shaft System in Water Turbine Generator Set
Institute of Scientific and Technical Information of China (English)
MA Zhenyue; SONG Zhiqiang
2009-01-01
A 3D finite element vibration model of water turbine generator set is constructed considering the coupling with hydropower house foundation. The method of determining guide bearing dynamic characteristic coefficients according to the swing of the shaft is proposed, which can be used for studying the self-vibration characteristic and stability of the water turbine generator set. The method fully considers the complex supporting boundary and loading conditions; especially the nonlinear variation of guide bearing dynamic characteristic coefficients and the coupling effect of the whole power-house foundation. The swing and critical rotating speed of an actual generator set shaft system are calculated. The simulated results of the generator set indicate that the coupling vibration model and calculation method presented in this paper are suitable for stability analysis of the water turbine generator set.
Transmission characteristics of MERS and SARS in the healthcare setting: a comparative study.
Chowell, Gerardo; Abdirizak, Fatima; Lee, Sunmi; Lee, Jonggul; Jung, Eunok; Nishiura, Hiroshi; Viboud, Cécile
2015-09-03
The Middle East respiratory syndrome (MERS) coronavirus has caused recurrent outbreaks in the Arabian Peninsula since 2012. Although MERS has low overall human-to-human transmission potential, there is occasional amplification in the healthcare setting, a pattern reminiscent of the dynamics of the severe acute respiratory syndrome (SARS) outbreaks in 2003. Here we provide a head-to-head comparison of exposure patterns and transmission dynamics of large hospital clusters of MERS and SARS, including the most recent South Korean outbreak of MERS in 2015. To assess the unexpected nature of the recent South Korean nosocomial outbreak of MERS and estimate the probability of future large hospital clusters, we compared exposure and transmission patterns for previously reported hospital clusters of MERS and SARS, based on individual-level data and transmission tree information. We carried out simulations of nosocomial outbreaks of MERS and SARS using branching process models rooted in transmission tree data, and inferred the probability and characteristics of large outbreaks. A significant fraction of MERS cases were linked to the healthcare setting, ranging from 43.5 % for the nosocomial outbreak in Jeddah, Saudi Arabia, in 2014 to 100 % for both the outbreak in Al-Hasa, Saudi Arabia, in 2013 and the outbreak in South Korea in 2015. Both MERS and SARS nosocomial outbreaks are characterized by early nosocomial super-spreading events, with the reproduction number dropping below 1 within three to five disease generations. There was a systematic difference in the exposure patterns of MERS and SARS: a majority of MERS cases occurred among patients who sought care in the same facilities as the index case, whereas there was a greater concentration of SARS cases among healthcare workers throughout the outbreak. Exposure patterns differed slightly by disease generation, however, especially for SARS. Moreover, the distributions of secondary cases per single primary case varied
Shen, Chunyun; Zhang, Yuwen; Li, Zheng
2016-01-01
Natural convection in a cylinder with an internally slotted annulus was solved by SIMPLE algorithm, and the effects of different slotted structures on nonlinear characteristics of natural convection were investigated. The results show that the equivalent thermal conductivity Keq increases with Rayleigh number, and reaches the maximum in the vertical orientation. Nonlinear results were obtained by simulating the fluid flow at different conditions. With increasing Rayleigh number, heat transfer is intensified and the state of heat transfer changes from the steady to unsteady. We investigated different slotted structures effects on natural convection, and analyze the corresponding nonlinear characteristics.
Institute of Scientific and Technical Information of China (English)
Qiang Zheng; Yi-hu Song; Xiao-su Yi
2001-01-01
The nonlinear J-E characteristics under self-heating equilibrium for conductive composites based on high density polyethylene were studied. The results show that there are identical conduction mechanisms under self-heating equilibrium for the composites with various initial resistivities determined by filler content or ambient temperature. The nonlinear conduction behavior was involved in the limited microstructure transformations of the conducting network induced by electrical field applied and the corresponding self-heating effect. A reversible thermal fuse (RTF) model was suggested to interpret the physical origin of the nonlinear J-E characteristics.
Institute of Scientific and Technical Information of China (English)
桂永方; 朱如鹏; 靳广虎; 李枝军
2014-01-01
Based on the method of lumped parameters,a dynamic model was established for a 2-input cylindrical gear split-torque transmission system considering time-varying mesh stiffness,backlashes and mesh damping.Through solving its dynamic equations with the fourth order Runge-Kutta method,the dynamic load sharing coefficients of the system were acquired.The results showed that the load sharing coefficient of the split-torque stages increases with increase in backlash of single branch in split-torque stages,and it decreases with increase in backlash of dual-branch in split-torque stages;the backlashes of single-branch and dual-branch in split-torque stages have a smaller impact on the load sharing coefficient of synthesized torque stages;the load sharing coefficient of the synthesized torque stages increases with increase in backlash of single branch in synthesized torque stages,and it decreases with increase in backlash of dual-branch in synthesized torque stages;the backlashes of single-branch and dual-branch in synthesized torque stages have a smaller impact on the load sharing coefficient of split-torque stages;the dynamic load coefficient increases with increase in backlash of dual-branch.%基于集中参数，建立了双输入圆柱齿轮分流传动系统的弯扭耦合动力学模型，模型中考虑了各齿轮副间的齿侧间隙、时变啮合刚度、啮合阻尼等因素。采用四阶龙格-库塔法，求解系统动力学方程，获得了系统的动力学均载系数。分析了齿侧间隙对均载系数的影响，获得了齿侧间隙对分流级、并车级均载系数的变化规律。研究结果表明：分流级均载系数随分流级单分支齿侧间隙增加而增大，随分流级双分支齿侧间隙增加而减小；分流级单分支、双分支齿侧间隙对并车级均载系数影响较小；并车级均载随并车级单分支齿侧间隙增加而增大，随并车级双分支齿侧间隙增加而减小；并车级单分支、双
Current transmission and nonlinear effects in un-gated thermionic cathode RF guns
Energy Technology Data Exchange (ETDEWEB)
Edelen, J. P. [Fermilab; Harris, J. R. [Air Force Weapons Lab
2017-05-03
Un-gated thermionic cathode RF guns are well known as a robust source of electrons for many accelerator applications. These sources are in principle scalable to high currents without degradation of the transverse emittance due to control grids but they are also known for being limited by back-bombardment. While back-bombardment presents a significant limitation, there is still a lack of general understanding on how emission over the whole RF period will affect the nature of the beams produced from these guns. In order to improve our understanding of how these guns can be used in general we develop analytical models that predict the transmission efficiency as a function of the design parameters, study how bunch compression and emission enhancement caused by Schottky barrier lowering affect the output current profile in the gun, and study the onset of space-charge limited effects and the resultant virtual cathode formation leading to a modulation in the output current distribution.
Razzaq, Zia
1989-01-01
Straight or curved hat-section members are often used as structural stiffeners in aircraft. For instance, they are employed as stiffeners for the dorsal skin as well as in the aerial refueling adjacent area structure in F-106 aircraft. The flanges of the hat-section are connected to the aircraft skin. Thus, the portion of the skin closing the hat-section interacts with the section itself when resisting the stresses due to service loads. The flexural fatigue life of such a closed section is estimated using materially nonlinear axial fatigue characteristics. It should be recognized that when a structural shape is subjected to bending, the fatigue life at the neutral axis is infinity since the normal stresses are zero at that location. Conversely, the fatigue life at the extreme fibers where the normal bending stresses are maximum can be expected to be finite. Thus, different fatigue life estimates can be visualized at various distances from the neural axis. The problem becomes compounded further when significant portions away from the neutral axis are stressed into plastic range. A theoretical analysis of the closed hat-section subjected to flexural cyclic loading is first conducted. The axial fatigue characteristics together with the related axial fatigue life formula and its inverted form given by Manson and Muralidharan are adopted for an aluminum alloy used in aircraft construction. A closed-form expression for predicting the flexural fatigue life is then derived for the closed hat-section including materially nonlinear action. A computer program is written to conduct a study of the variables such as the thicknesses of the hat-section and the skin, and the type of alloy used. The study has provided a fundamental understanding of the flexural fatigue life characteristics of a practical structural component used in aircraft when materially nonlinear action is present.
Zhang, L.; Yu, C.; Sun, J. Q.
2015-03-01
It is difficult to simulate the dynamical behavior of actual financial markets indexes effectively, especially when they have nonlinear characteristics. So it is significant to propose a mathematical model with these characteristics. In this paper, we investigate a generalized Weierstrass-Mandelbrot function (WMF) model with two nonlinear characteristics: fractal dimension D where 2 > D > 1.5 and Hurst exponent (H) where 1 > H > 0.5 firstly. And then we study the dynamical behavior of H for WMF as D and the spectrum of the time series γ change in three-dimensional space, respectively. Because WMF and the actual stock market indexes have two common features: fractal behavior using fractal dimension and long memory effect by Hurst exponent, we study the relationship between WMF and the actual stock market indexes. We choose a random value of γ and fixed value of D for WMF to simulate the S&P 500 indexes at different time ranges. As shown in the simulation results of three-dimensional space, we find that γ is important in WMF model and different γ may have the same effect for the nonlinearity of WMF. Then we calculate the skewness and kurtosis of actual Daily S&P 500 index in different time ranges which can be used to choose the value of γ. Based on these results, we choose appropriate γ, D and initial value into WMF to simulate Daily S&P 500 indexes. Using the fit line method in two-dimensional space for the simulated values, we find that the generalized WMF model is effective for simulating different actual stock market indexes in different time ranges. It may be useful for understanding the dynamical behavior of many different financial markets.
Linear and nonlinear optical characteristics of Te nanoparticles-doped germanate glasses
Xu, Zhousu; Guo, Qiangbing; Liu, Chang; Ma, Zhijun; Liu, Xiaofeng; Qiu, Jianrong
2016-10-01
Te nanoparticles (NPs)-doped GeO2-MgO-B2O3-Al2O3-TeO2 glasses were prepared by the conventional melt-quenching method. Based on X-ray photoelectron spectroscopy, Raman spectroscopy and transmission electron microscope observation, the coloration of the glass at high TeO2 concentration is ascribed to the precipitation of elemental Te NPs with a size of 5-10 nm in the germanate glass. Optical absorption spectra and nonlinear optical (NLO) properties of the glass samples were analyzed by UV-3600 spectrophotometry and Z-scan technique, respectively. The nonlinear absorption coefficient ( β) and the imaginary part of the third-order NLO susceptibility (Im χ (3)) were estimated to be 1.74 cm/GW and 1.142 × 10-12 esu for laser power of 95 μW, respectively. Due to the excellent NLO properties, the Te NPs-doped germanate glasses may have potential applications for ultrafast optical switch and photonics.
Institute of Scientific and Technical Information of China (English)
Chien-Yu Lin; Rameez Asif; Michael Holtmannspoetter; Bernhard Schmauss
2012-01-01
Non-uniform step-size distribution is implemented for split-step based nonlinear compensation in single-channel 112-Gb/s 16 quadrature amplitude modulation (QAM) transmission. Numerical simulations of the system including a 20x80 km uncompensated link are performed using logarithmic step size distribution to compensate signal distortions. 50% of reduction in number of steps with respect to using constant step sizes is observed. The performance is further improved by optimizing nonlinear calculating position (NLCP) in case of using constant step sizes while NLCP optimization becomes unnecessary when using logarithmic step sizes, which reduces the computational effort due to uniformly distributed nonlinear phase for all successive steps.%Non-uniform step-size distribution is implemented for split-step based nonlinear compensation in singlechannel 112-Gb/s 16 quadrature amplitude modulation (QAM) transmission.Numerical simulations of the system including a 20×80 km uncompensated link are performed using logarithmic step size distribution to compensate signal distortions.50％ of reduction in number of steps with respect to using constant step sizes is observed.The performance is further improved by optimizing nonlinear calculating position (NLCP) in case of using constant step sizes while NLCP optimization becomes unnecessary when using logarithmic step sizes,which reduces the computational effort due to uniformly distributed nonlinear phase for all successive steps.
Song, Yongduan; Guo, Junxia; Huang, Xiucai
2016-06-23
This paper considers the tracking control problem for a class of multi-input multi-output nonlinear systems subject to unknown actuation characteristics and external disturbances. Neuroadaptive proportional-integral (PI) control with self-tuning gains is proposed, which is structurally simple and computationally inexpensive. Different from traditional PI control, the proposed one is able to online adjust its PI gains using stability-guaranteed analytic algorithms without involving manual tuning or trial and error process. It is shown that the proposed neuroadaptive PI control is continuous and smooth everywhere and ensures the uniformly ultimately boundedness of all the signals of the closed-loop system. Furthermore, the crucial compact set precondition for a neural network (NN) to function properly is guaranteed with the barrier Lyapunov function, allowing the NN unit to play its learning/approximating role during the entire system operation. The salient feature also lies in its low complexity in computation and effectiveness in dealing with modeling uncertainties and nonlinearities. Both square and nonsquare nonlinear systems are addressed. The benefits and the feasibility of the developed control are also confirmed by simulations.
Directory of Open Access Journals (Sweden)
E. L. Dmitrieva
2016-05-01
Full Text Available Basic peculiarities of nonlinear Kalman filtering algorithm applied to processing of interferometric signals are considered. Analytical estimates determining statistical characteristics of signal values prediction errors were obtained and analysis of errors histograms taking into account variations of different parameters of interferometric signal was carried out. Modeling of the signal prediction procedure with known fixed parameters and variable parameters of signal in the algorithm of nonlinear Kalman filtering was performed. Numerical estimates of prediction errors for interferometric signal values were obtained by formation and analysis of the errors histograms under the influence of additive noise and random variations of amplitude and frequency of interferometric signal. Nonlinear Kalman filter is shown to provide processing of signals with randomly variable parameters, however, it does not take into account directly the linearization error of harmonic function representing interferometric signal that is a filtering error source. The main drawback of the linear prediction consists in non-Gaussian statistics of prediction errors including cases of random deviations of signal amplitude and/or frequency. When implementing stochastic filtering of interferometric signals, it is reasonable to use prediction procedures based on local statistics of a signal and its parameters taken into account.
Nonlinear evolution characteristics of the climate system on the interdecadal-centennial timescale
Institute of Scientific and Technical Information of China (English)
Gao Xin-Quan; Zhang Wen
2005-01-01
To better understand the physical mechanism of the climate change on interdecadal-centennial timescale, this paper focuses on analysing and modelling the evolution characteristics of the climate change. The method of wavelet transform is used to pick out the interdecadal timescale oscillations from long-term instrumental observations, natural proxy records, and modelling series. The modelling series derived from the most simplified nonlinear climatic model are used to identify whether modifications are concerned with some forcings such as the solar radiation on the climate system. The results show that two major oscillations exist in various observations and model series, namely the 2030a and the 60-70a timescale respectively, and these quasi-periodicities are modulated with time. Further, modelling results suggest that the originations of these oscillations are not directly linked with the periodic variation of solar radiations such as the 1-year cycle, the 11-year cycle, and others, but possibly induced by the internal nonlinear effects of the climate system. It seems that the future study on the genesis of the climate change with interdecadal-centennial timescale should focus on the internal nonlinear dynamics in the climate system.
Experimental damage detection of cracked beams by using nonlinear characteristics of forced response
Andreaus, U.; Baragatti, P.
2012-08-01
Experimental evaluation of the flexural forced vibrations of a steel cantilever beam having a transverse surface crack extending uniformly along the width of the beam was performed, where an actual fatigue crack was introduced instead - as usual - of a narrow slot. The nonlinear aspects of the dynamic response of the beam under harmonic excitation were considered and the relevant quantitative parameters were evaluated, in order to relate the nonlinear resonances to the presence and size of the crack. To this end, the existence of sub- and super-harmonic components in the Fourier spectra of the acceleration signals was evidenced, and their amplitudes were quantified. In particular, the acceleration signals were measured in different positions along the beam axis and under different forcing levels at the beam tip. The remarkable relevance of the above mentioned nonlinear characteristics, and their substantial independence on force magnitude and measurement point were worthily noted in comparison with the behavior of the intact beam. Thus, a reliable method of damage detection was proposed which was based on simple tests requiring only harmonically forcing and acceleration measuring in any point non-necessarily near the crack. Then, the time-history of the acceleration recorded at the beam tip was numerically processed in order to obtain the time-histories of velocity and displacement. The nonlinear features of the forced response were described and given a physical interpretation in order to define parameters suitable for damage detection. The efficiency of such parameters was discussed with respect to the their capability of detecting damage and a procedure for damage detection was proposed which was able to detect even small cracks by using simple instruments. A finite element model of the cantilever beam was finally assembled and tuned in order to numerically simulate the results of the experimental tests.
Wang, Zhi-Gong; Lü, Xiao-Ying; Gao, Jian-Yun; Wang, Yu-Hang; Huang, Cen-Yu; Chen, Yue-Lin; Xing, Li-Yang; Wang, Gui-Ying
2011-08-01
Study on features of acupoints with resistance test in the past half century is reviewed in this article. Mechanism and technology of the method are introduced as well as its shortcomings. The determination method of signal transmission along meridians with the combination of electrical network theories and practice is advanced. And the result of a series experiments on one meridian at the superficial part of the body are given as well. Thus, it is concluded that the signals of the point-in/point-out and the signals along a non-meridian path with the same distance are significantly different, which gives a verification of the feasibility of the method by using electrical network theories to set out characteristics of signal transmission along meridians dynamically.
Application of the Characteristic Time Expansion Method for Estimating Nonlinear Restoring Forces
Directory of Open Access Journals (Sweden)
Yung-Wei Chen
2013-01-01
Full Text Available This paper proposes a characteristic time expansion method (CTEM for estimating nonlinear restoring forces. Because noisy data and numerical instability are the main causes of numerical developing problems in an inverse field, a polynomial to identify restoring forces is usually adopted to eliminate these problems. However, results of the way doing are undesirable for a high order of polynomial. To overcome this difficulty, the characteristic length (CL is introduced into the power series, and a natural regularization technique is applied to ensure numerical stability and determine the existence of a solution. As compared to previous solutions presented in other researches, the proposed method is a desirable and accurate solver for the problem of restoring the force in the inverse vibration problems.
Non-linear characteristics and long-range correlations in Asian stock markets
Jiang, J.; Ma, K.; Cai, X.
2007-05-01
We test several non-linear characteristics of Asian stock markets, which indicates the failure of efficient market hypothesis and shows the essence of fractal of the financial markets. In addition, by using the method of detrended fluctuation analysis (DFA) to investigate the long range correlation of the volatility in the stock markets, we find that the crossover phenomena exist in the results of DFA. Further, in the region of small volatility, the scaling behavior is more complicated; in the region of large volatility, the scaling exponent is close to 0.5, which suggests the market is more efficient. All these results may indicate the possibility of characteristic multifractal scaling behaviors of the financial markets.
Directory of Open Access Journals (Sweden)
Yohannes S.M. Simamora
2014-09-01
Full Text Available A simple approach of active surge control of compression systems is presented. Specifically, nonlinear components of the pressure ratio and rotating speed states of the Moore-Greitzer model are transferred into the input vectors. Subsequently, the compressor characteristic is linearized into two modes, which describe the stable region and the unstable region respectively. As a result, the system’s state and input matrices both appear linear, to which linear realization and analysis are applicable. A linear quadratic regulator plus integrator is then chosen as closed-loop controller. By simulation it was shown that the modified model and characteristics can describe surge behavior, while the closed-loop controller can stabilize the system in the unstable operating region. The last-mentioned was achieved when massflow was 5.38 per cent less than the surge point.
Gan, Deying; Hu, Weiping; Zhao, Bingxin
2014-10-01
By analyzing the mechanism of pronunciation, traditional acoustic parameters, including fundamental frequency, Mel frequency cepstral coefficients (MFCC), linear prediction cepstrum coefficient (LPCC), frequency perturbation, amplitude perturbation, and nonlinear characteristic parameters, including entropy (sample entropy, fuzzy entropy, multi-scale entropy), box-counting dimension, intercept and Hurst, are extracted as feature vectors for identification of pathological voice. Seventy-eight normal voice samples and 73 pathological voice samples for /a/, and 78 normal samples and 80 pathological samples for /i/ are recognized based on support vector machine (SVM). The results showed that compared with traditional acoustic parameters, nonlinear characteristic parameters could be well used to distinguish between healthy and pathological voices, and the recognition rates for /a/ were all higher than those for /i/ except for multi-scale entropy. That is why the /a/ sound data is used widely in related research at home and abroad for obtaining better identification of pathological voices. Adopting multi-scale entropy for /i/ could obtain higher recognition rate than /a/ between healthy and pathological samples, which may provide some useful inspiration for evaluating vocal compensatory function.
Nonlinear Vibration Characteristics of a Flexible Blade with Friction Damping due to Tip-Rub
Directory of Open Access Journals (Sweden)
Dengqing Cao
2011-01-01
Full Text Available An approximate approach is proposed in this paper for analyzing the two-dimensional friction contact problem so as to compute the dynamic response of a structure constrained by friction interfaces due to tip-rub. The dynamical equation of motion for a rotational cantilever blade in a centrifugal force field is established. Flow-induced distributed periodic forces and the internal material damping in the blade are accounted for in the governing equation of motion. The Galerkin method is employed to obtain a three-degree-of-freedom oscillator with friction damping due to tip-rub. The combined motion of impact and friction due to tip-rub produced a piecewise linear vibration which is actually nonlinear. Thus, a complete vibration cycle is divided into successive intervals. The system possesses linear vibration characteristic during each of these intervals, which can be determined using analytical solution forms. Numerical simulation shows that the parameters such as gap of the tip and the rotational speed of the blades have significant effects on the dynamical responses of the system. Finally, the nonlinear vibration characteristics of the blade are investigated in terms of the Poincare graph, and the frequency spectrum of the responses and the amplitude-frequency curves.
Directory of Open Access Journals (Sweden)
Gaosheng Luo
2014-01-01
Full Text Available A robust adaptive control method with full-state feedback is proposed based on the fact that the elbow joint of a seven-function hydraulic manipulator with double-screw-pair transmission features the following control characteristics: a strongly nonlinear hydraulic system, parameter uncertainties susceptible to temperature and pressure changes of the external environment, and unknown outer disturbances. Combined with the design method of the back-stepping controller, the asymptotic stability of the control system in the presence of disturbances from uncertain systematic parameters and unknown external disturbances was demonstrated using Lyapunov stability theory. Based on the elbow joint of the seven-function master-slave hydraulic manipulator for the 4500 m Deep-Sea Working System as the research subject, a comparative study was conducted using the control method presented in this paper for unknown external disturbances. Simulations and experiments of different unknown outer disturbances showed that (1 the proposed controller could robustly track the desired reference trajectory with satisfactory dynamic performance and steady accuracy and that (2 the modified parameter adaptive laws could also guarantee that the estimated parameters are bounded.
Study on Transmission Torque Characteristics of a Surface-Permanent-Magnet-Type Magnetic Gear
Niguchi, Noboru; Hirata, Katsuhiro; Hayakawa, Yuichi
Magnetic gears have some advantages such as low mechanical loss and maintenance-free operation that are not observed in conventional mechanical gears. In addition, magnetic gears have inherent overload protection. Therefore, magnetic gears are expected to be used in special applications; for example, they can be used in a joint of a humanoid robot. Recently, various types of new magnetic gears have been proposed. Among these new gears, a surface-permanent-magnet-type (SPM-type) magnetic gear employing harmonic magnetic flux has gained attention because of its high transmission torque density, though it has a complex structure with multipole magnets. Some studies on an SPM-type magnetic gear have been carried out, but there are few papers on cogging torque. This paper describes the transmission torque characteristics of an SPM-type magnetic gear. The operating principle and the transmission torque under synchronous operation are formulated in accordance with the gear ratio. High orders of the cogging torque are computed by employing the 3-D finite element method, and the validity of the analysis is verified by carrying out measurements on a prototype. Furthermore, a method for reducing the cogging torque is discussed.
Numerical Calculation of Transient Thermal Characteristics in Gas-Insulated Transmission Lines
Directory of Open Access Journals (Sweden)
Hongtao Li
2013-11-01
Full Text Available For further knowledge of the thermal characteristics in gas-insulated transmission lines (GILs installed above ground, a finite-element model coupling fluid field and thermal field is established, in which the corresponding assumptions and boundary conditions are given. Â Transient temperature rise processes of the GIL under the conditions of variable ambient temperature, wind velocity and solar radiation are respectively investigated. Equivalent surface convective heat transfer coefficient and heat flux boundary conditions are updated in the analysis process. Unlike the traditional finite element methods (FEM, the variability of the thermal properties with temperature is considered. The calculation results are validated by the tests results reported in the literature. The conclusion provides method and theory basis for the knowledge of transient temperature rise characteristics of GILs in open environment.
Yamgoué, Serge Bruno; Pelap, François Beceau
2016-05-01
We revisit the derivation of the equation modeling envelope waves in a discrete nonlinear electrical transmission line (NLTL) considered a few years back in Physics Letters A 373 (2009) 3801-3809. Using a combination of rotating wave approximation and the Gardner-Morikawa transformation, we show that the modulated waves are described by a new type of extended nonlinear Schrödinger equation. In addition the expressions of several coefficients of this equation are found to be strongly different from those given earlier. As a consequence, key relationships between these coefficients that sustained the previous analysis are broken.
Transmission Characteristics in Tubular Acoustic Metamaterials Studied with Fluid Impedance Theory
Institute of Scientific and Technical Information of China (English)
FAN Li; ZHANG Shu-Yi; ZHANG Hui
2011-01-01
Tubular acoustic metamaterials with negative densities composed of periodical membranes set up along pipes are studied with the fluid impedance theory. In addition to the conventional forbidden bands induced by the Bragg-scattering due to the periodic distributions of different acoustic impedances, the low-frequency forbidden band (LFB) with the low-frequency limit of zero Hertz is studied, in which the LFB is explained with acoustic impedance matching and the Bloch theory. Furthermore, the influences of the structural parameters of the tubular acoustic metamaterials on the transmission characteristics, such as the transmission coefficients, dispersion curves, widths of forbidden and pass bands, fluctuations in pass bands, etc., are evaluated, which can be used in the optimization of the acoustic insulation ability of the metamaterials.%Tubular acoustic metamaterials with negative densities composed of periodical membranes set up along pipes are studied with the fluid impedance theory.In addition to the conventional forbidden bands induced by the Bragg-scattering due to the periodic distributions of different acoustic impedances,the low-frequency forbidden band (LFB) with the low-frequency limit of zero Hertz is studied,in which the LFB is explained with acoustic impedance matching and the Bloch theory.Furthermore,the influences of the structural parameters of the tubular acoustic metamaterials on the transmission characteristics,such as the transmission coefficients,dispersion curves,widths of forbidden and pass bands,fluctuations in pass bands,etc.,are evaluated,which can be used in the optimization of the acoustic insulation ability of the metamaterials.Like electromagnetic metamaterials,acoustic metamaterials have been presented with different structures,which have negative constitutive parameters of acoustic propagation and can realize unique acoustic characteristics and applications.[1-5] Recently,acoustic metamaterials were introduced into acoustic resonance
Tian, Zhang; Yanfeng, Gong
2017-05-01
In order to solve the contradiction between demand and distribution range of primary energy resource, Ultra High Voltage (UHV) power grids should be developed rapidly to meet development of energy bases and accessing of large-scale renewable energy. This paper reviewed the latest research processes of AC/DC transmission technologies, summarized the characteristics of AC/DC power grids, concluded that China’s power grids certainly enter a new period of large -scale hybrid UHV AC/DC power grids and characteristics of “strong DC and weak AC” becomes increasingly pro minent; possible problems in operation of AC/DC power grids was discussed, and interaction or effect between AC/DC power grids was made an intensive study of; according to above problems in operation of power grids, preliminary scheme is summarized as fo llows: strengthening backbone structures, enhancing AC/DC transmission technologies, promoting protection measures of clean energ y accessing grids, and taking actions to solve stability problems of voltage and frequency etc. It’s valuable for making hybrid UHV AC/DC power grids adapt to operating mode of large power grids, thus guaranteeing security and stability of power system.
Directory of Open Access Journals (Sweden)
Andrew Speakman
Full Text Available Life expectancy for people diagnosed with HIV has improved dramatically however the number of new infections in the UK remains high. Understanding patterns of sexual behaviour among people living with diagnosed HIV, and the factors associated with having condom-less sex, is important for informing HIV prevention strategies and clinical care. In addition, in view of the current interest in a policy of early antiretroviral treatment (ART for all people diagnosed with HIV in the UK, it is of particular importance to assess whether ART use is associated with increased levels of condom-less sex. In this context the ASTRA study was designed to investigate current sexual activity, and attitudes to HIV transmission risk, in a large unselected sample of HIV-infected patients under care in the UK. The study also gathered background information on demographic, socio-economic, lifestyle and disease-related characteristics, and physical and psychological symptoms, in order to identify other key factors impacting on HIV patients and the behaviours which underpin transmission. In this paper we describe the study rationale, design, methods, response rate and the demographic characteristics of the participants. People diagnosed with HIV infection attending 8 UK HIV out-patient clinics in 2011-2012 were invited to participate in the study. Those who agreed to participate completed a confidential, self-administered pen-and-paper questionnaire, and their latest CD4 count and viral load test results were recorded. During the study period, 5112 eligible patients were invited to take part in the study and 3258 completed questionnaires were obtained, representing a response rate of 64% of eligible patients. The study includes 2248 men who have sex with men (MSM, 373 heterosexual men and 637 women. Future results from ASTRA will be a key resource for understanding HIV transmission within the UK, targeting prevention efforts, and informing clinical care of individuals
Nonlinear current-voltage characteristics of sintered tungsten-vanadium oxide
Institute of Scientific and Technical Information of China (English)
Liu Zu-Li; Yang Lin-Feng; Wang Yu; Yao Kai-Lun; Wang Chuan-Cong
2004-01-01
We have studied the densification behaviour, microstructure and electrical properties of WO3 ceramics with V2O5as the additive ranging from 0.5 to 15mo1%. Scanning electron microscopic photos indicated that the grain size of WO3-V2O5 specimens is smaller than that of pure WO3. The addition of V2O5 to WO3 showed a tendency to enhance the densification rate and to restrict the grain growth. Electrical properties of all specimens were measured for different electrodes at different temperatures. The formation of the grain boundary barrier layer was confirmed by the non-ohmic I-V behaviour. The nonlinear coefficient was obtained at the current density J=0.01, 0.1 and 1mA-cm2 for a series of WO3-V2O5 samples. The V0.Smol% specimen showed an abnormal phenomenon that the nonlinear characteristics appeared at 350℃ and disappeared at lower and higher temperatures. This implies that it could be applied as a hightemperature varistor. The double Schottky barrier model was adopted to explain the phenomena for the WO3-V2O5varistors.
Briley, Daniel A; Harden, K Paige; Tucker-Drob, Elliot M
2014-12-01
Parents' expectations for their children's ultimate educational attainment have been hypothesized to play an instrumental role in socializing academically relevant child behaviors, beliefs, and abilities. In addition to social transmission of educationally relevant values from parents to children, parental expectations and child characteristics may transact bidirectionally. We explore this hypothesis using both longitudinal and genetically informative twin data from the Early Childhood Longitudinal Study-Birth and Kindergarten cohorts. Our behavior genetic results indicate that parental expectations partly reflect child genetic variation, even as early as 4 years of age. Two classes of child characteristics were hypothesized to contribute to these child-to-parent effects: behavioral tendencies (approaches toward learning and problem behaviors) and achievement (math and reading). Using behavior genetic models, we find within-twin-pair associations between these child characteristics and parental expectations. Using longitudinal cross-lagged models, we find that initial variation in child characteristics predicts future educational expectations above and beyond previous educational expectations. These results are consistent with transactional frameworks in which parent-to-child and child-to-parent effects co-occur. PsycINFO Database Record (c) 2014 APA, all rights reserved.
Institute of Scientific and Technical Information of China (English)
QIN Xin-qiang; MA Yi-chen; ZHANG Yin
2005-01-01
For two-dimension nonlinear convection diffusion equation, a two-grid method of characteristics finite-element solution was constructed. In this method the nonlinear iterations is only to execute on the coarse grid and the fine-grid solution can be obtained in a single linear step. For the nonlinear convection-dominated diffusion equation, this method can not only stabilize the numerical oscillation but also accelerate the convergence and improve the computational efficiency. The error analysis demonstrates if the mesh sizes between coarse-grid and fine-grid satisfy the certain relationship, the two-grid solution and the characteristics finite-element solution have the same order of accuracy. The numerical example confirms that the two-grid method is more efficient than that of characteristics finite-element method.
Directory of Open Access Journals (Sweden)
Wu Jing
2013-06-01
Full Text Available Quantitative measurement on instantaneous concentration field not only can provide scientific methods for people measuring environment wind tunnel, but also can provide important data for solving convection--diffusion problem in practical project. The established large environment and wind engineering wind tunnel needs to develop the measurement system of instantaneous concentration field in order to study concentration field of environmental pollution diffusion. Based on collecting, analyzing and selecting a large number of literatures, the paper comprehensively studies the image measurement of instantaneous concentration field, and develops the complete software and hardware system. And the developed measurement system is used to measure the results, and the nonlinear characteristics of instable concentration field are studied. Combined with experimental fluid mechanics, information technology, optical scattering and imaging theory, the paper makes quantitative calculation on instability of concentration field from an experimental point of view, which provides an important experimental result for using numerical method to explore the instability of concentration field.
Directory of Open Access Journals (Sweden)
Zhi-Wen Zhu
2015-01-01
Full Text Available A kind of high-aspect-ratio shape memory alloy (SMA composite wing is proposed to reduce the wing’s fluttering. The nonlinear dynamic characteristics and optimal control of the SMA composite wings subjected to in-plane stochastic excitation are investigated where the great bending under the flight loads is considered. The stochastic stability of the system is analyzed, and the system’s response is obtained. The conditions of stochastic Hopf bifurcation are determined, and the probability density of the first-passage time is obtained. Finally, the optimal control strategy is proposed. Numerical simulation shows that the stability of the system varies with bifurcation parameters, and stochastic Hopf bifurcation appears in the process; the reliability of the system is improved through optimal control, and the first-passage time is delayed. Finally, the effects of the control strategy are proved by experiments. The results of this paper are helpful for engineering applications of SMA.
Directory of Open Access Journals (Sweden)
M. Simić
2014-06-01
Full Text Available This paper describes the realization of a three-phase transformer model based on a non-linear open-circuit characteristic. The proposed model is based on the fact that in case of a star connection with a neutral wire on the primary windings for all three phases, the applied voltage presents phase voltage and line (phase currents are magnetization currents. These variables are available for measuring and it is easy to obtain three non-linear open circuit characteristics. The results of simulations and a comparison with references and experimental results verified this approach.
Institute of Scientific and Technical Information of China (English)
YAN Minhui; CHEN Jianping
2002-01-01
This paper analyzes the high bit-rate optical pulse trasmission in single mode optical fiber with chromatic dispersion, polarization mode dispersion (small random birefringence) and nonlinearity. Numerical method employed can precisely describe their interactive effect on transmission performance. Different dispersion maps and the related performance are analysed. Various simulation results and discussion are given. The results show that chromatic dispersion compensation should be carefully designed. Appropriate dispersion management can also alleviate the effect of polarization mode dispersion.
Arunkumar, M. P.; Jagadeesh, M.; Pitchaimani, Jeyaraj; Gangadharan, K. V.; Babu, M. C. Lenin
2016-11-01
This paper presents the results of numerical studies carried out on vibro-acoustic and sound transmission loss behaviour of aluminium honeycomb core sandwich panel with fibre reinforced plastic (FRP) facings. Layered structural shell element with equivalent orthotropic elastic properties of core and orthotropic properties of FRP facing layer is used to predict the free and forced vibration characteristics. Followed by this, acoustic response and transmission loss characteristics are obtained using Rayleigh integral. Vibration and acoustic characteristics of FRP sandwich panels are compared with aluminium sandwich panels. The result reveals that FRP panel has better vibro-acoustic and transmission loss characteristics due to high stiffness and inherent material damping associated with them. Resonant amplitudes of the response are fully controlled by modal damping factors calculated based on modal strain energy. It is also demonstrated that FRP panel can be used to replace the aluminium panel without losing acoustic comfort with nearly 40 percent weight reduction.
Directory of Open Access Journals (Sweden)
Tomotada Iwamoto
Full Text Available Beijing family strains of Mycobacterium tuberculosis have attracted worldwide attention because of their wide geographical distribution and global emergence. Peru, which has a historical relationship with East Asia, is considered to be a hotspot for Beijing family strains in South America. We aimed to unveil the genetic diversity and transmission characteristics of the Beijing strains in Peru. A total of 200 Beijing family strains were identified from 2140 M. tuberculosis isolates obtained in Lima, Peru, between December 2008 and January 2010. Of them, 198 strains were classified into sublineages, on the basis of 10 sets of single nucleotide polymorphisms (SNPs. They were also subjected to variable number tandem-repeat (VNTR typing using an international standard set of 15 loci (15-MIRU-VNTR plus 9 additional loci optimized for Beijing strains. An additional 70 Beijing family strains, isolated between 1999 and 2006 in Lima, were also analyzed in order to make a longitudinal comparison. The Beijing family was the third largest spoligotyping clade in Peru. Its population structure, by SNP typing, was characterized by a high frequency of Sequence Type 10 (ST10, which belongs to a modern subfamily of Beijing strains (178/198, 89.9%. Twelve strains belonged to the ancient subfamily (ST3 [n=3], ST25 [n=1], ST19 [n=8]. Overall, the polymorphic information content for each of the 24 loci values was low. The 24 loci VNTR showed a high clustering rate (80.3% and a high recent transmission index (RTI(n-1=0.707. These strongly suggest the active and on-going transmission of Beijing family strains in the survey area. Notably, 1 VNTR genotype was found to account for 43.9% of the strains. Comparisons with data from East Asia suggested the genotype emerged as a uniquely endemic clone in Peru. A longitudinal comparison revealed the genotype was present in Lima by 1999.
Directory of Open Access Journals (Sweden)
V. V. Mikhailau
2016-01-01
Full Text Available Semi-natural tests for active pneumatic suspension of a 18-tonne tourist bus with the system of automatic body stabilization of the mobile machine and feed-back coupling according to kinematics parameter. The test have been executed in the cases when the bus is stocked with an automatic hydro-mechanical transmission in the process of speed picking up, gear-changing or road braking which is assigned by accidental road humps. A computer simulation of dynamic structures in combination with virtual devices and real objects (HIL – Hardware-in-the-Loop Simulation has been carried in the paper. Personal computers, software, programmed logic controller, frequency generator, solenoid-operated valve have been used for the investigation process. The paper proposes an unconventional method for improvement operational characteristics which is based on integrated control of a suspension and automatic hydro-mechanical transmission. A mathematical model includes systems of automatic transmission, suspension and module for generation of accidental road humps. The model has been considered as a basis for semi-natural laboratory bench with industrially-manufactured controller, other components of automatic systems and standard control organs. The most efficient method for body stabilization is control of the suspension according to the parameter of angular rate during vertical turn of an automobile’s center line with a turning point in the center of mass. The developed algorithm and stabilization system according to angular rate of body’s center line turning have made it possible to improve dynamics of the bus while making gear-changing and to reduce fuel consumption during starting-up and speed picking-up processes. During the braking process such system simultaneously decreases oscillation amplitude of some parameters more than two-fold.
Jumps and bi-stability in the phase-gain characteristics of a nonlinear parametric amplifier
DEFF Research Database (Denmark)
Neumeyer, Stefan; van de Looij, Ruud; Thomsen, Jon Juel
2014-01-01
This work experimentally investigates the impact of nonlinearity on macromechanical parametric amplification. For a strong cubic stiffness nonlinearity we observe jumps in gain (ratio of steady-state vibration amplitude of the externally and parametrically excited system, to vibration amplitude...
Yang, Liu; Yang, Zhongcun; Wan, Jianing; Liu, Hao
2016-10-01
For the safety of electronic equipment, a double-layer barrier of cylindrical plasma array was designed, and its protective performance to high-power microwave (HPM) were analyzed and the protective performance experiment was conducted. Combining the density distribution characteristic of the discharge plasma, the shielding effectiveness of the double-layer plasma on 6GHz HPM pulse was studied. The experiment results indicate that the protective effectiveness of two layers plasma array is better than that of one layer. Two layers plasma array can make the peak electric field of transmission waveform less than interference threshold of electronic equipment to achieve better protection effectiveness. Transmission attenuation of one layer and two layers plasma array to HPM can reach -6.6066dB and -24.9357dB. The results also show that for the existence of multiple reflection, even the plasma electron density is not high enough, it can realize a strong attenuation. The experiment results in this paper are of great significance in protecting against HPM and electromagnetic pulse.
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
Multi-motor vibratory transmission systems have been wide used in large vibratory machines, and four-motor linear vibratory machine is one typical equipment of them. Under non-forcible synchronization condition zero-phase synchronization of the machine is non-stationary and π-phase synchronization is stable. Under half-forcible synchronization condition in which only one motor is controlled being synchronous to another, only lag synchronization near zero-phase synchronization can be realized. Both of the characteristics have never been revealed with classical theory quantitatively. The problem is solved by means of establishing an electromechanical coupling mathematical model of the system and numerical analysis of the starting processes.
HTS-FCL EMTDC model considering nonlinear characteristics on fault current and temperature
Energy Technology Data Exchange (ETDEWEB)
Yoon, Jae-Young; Lee, Seung-Ryul [Korea Electrotechnology Research Institute (Korea, Republic of)
2010-06-01
One of the most serious problems of the KEPCO system is a higher fault current than the CB(Circuit breaker's SCC (Short Circuit Capacity). There are so many alternatives to reduce the higher fault current, such as the isolation of bus ties, enhancement of the CB's SCC, and the application of HVDC-BTB (Back to Back) or FCL (fault current limiter). However, these alternatives have drawbacks from the viewpoint of system stability and cost. As superconductivity technology has been developed, the resistive type (R-type) HTS-FCL (High Temperature Superconductor Fault Current Limiter) offers one of the important alternatives in terms of power loss and cost reduction in solving the fault current problem. To evaluate the accurate transient performance of R-type HTS-FCL, it is necessary for the dynamic simulation model to consider transient characteristics during the quenching and the recovery state. Against this background, this paper presents the new HTS-FCL EMTDC (Electro-Magnetic Transients including Direct Current) model considering the nonlinear characteristics on fault current and temperature.
HTS-FCL EMTDC model considering nonlinear characteristics on fault current and temperature
Yoon, Jae-Young; Lee, Seung-Ryul
2010-06-01
One of the most serious problems of the KEPCO system is a higher fault current than the CB(Circuit breaker's SCC (Short Circuit Capacity). There are so many alternatives to reduce the higher fault current, such as the isolation of bus ties, enhancement of the CB's SCC, and the application of HVDC-BTB (Back to Back) or FCL (fault current limiter). However, these alternatives have drawbacks from the viewpoint of system stability and cost. As superconductivity technology has been developed, the resistive type (R-type) HTS-FCL (High Temperature Superconductor Fault Current Limiter) offers one of the important alternatives in terms of power loss and cost reduction in solving the fault current problem. To evaluate the accurate transient performance of R-type HTS-FCL, it is necessary for the dynamic simulation model to consider transient characteristics during the quenching and the recovery state. Against this background, this paper presents the new HTS-FCL EMTDC (Electro-Magnetic Transients including Direct Current) model considering the nonlinear characteristics on fault current and temperature.
Chen, Shibin; Li, Dichen; Tian, Xiaoyong; Han, Haoxue; Wu, Haihua
2012-03-01
The influence of a vertical coupled defect on the localized properties of a diamond electromagnetic bandgap (EBG) structure has been studied in the present research. The diamond EBG structure with a cavity defect was fabricated by stereolithography and gel-casting processes with alumina slurry. The resonant peaks of two kinds of defects were compared by measuring their microwave transmission characteristics using a network analyzer. A higher quality factor ( Q) was obtained for the diamond EBG structure with a vertical coupled defect, and the transmission efficiency of resonant peak was improved by 29.6% in comparison with a single defect. Experimental results agreed with the simulation results. These microwave transmission characteristics of the three-dimensional (3D) EBG structures indicate that they can be applied in microwave devices to improve transmission efficiency.
VanZante, Dale; Envia, Edmane
2008-01-01
Understanding the relative importance of the various turbine noise generation mechanisms and the characteristics of the turbine acoustic transmission loss are essential ingredients in developing robust reduced-order models for predicting the turbine noise signature. A computationally based investigation has been undertaken to help guide the development of a turbine noise prediction capability that does not rely on empiricism. The investigation relies on highly detailed numerical simulations of the unsteady flowfield inside a modern high-pressure turbine (HPT). The simulations are developed using TURBO, which is an unsteady Reynolds-averaged Navier-Stokes (URANS) code capable of multi-stage simulations. The purpose of this study is twofold. First, to determine an estimate of the relative importance of the contributions to the coherent part of the acoustic signature of a turbine from the three potential sources of turbine noise generation, namely, blade-row viscous interaction, potential field interaction, and entropic source associated with the interaction of the blade rows with the temperature nonuniformities caused by the incomplete mixing of the hot fluid and the cooling flow. Second, to develop an understanding of the turbine acoustic transmission characteristics and to assess the applicability of existing empirical and analytical transmission loss models to realistic geometries and flow conditions for modern turbine designs. The investigation so far has concentrated on two simulations: (1) a single-stage HPT and (2) a two-stage HPT and the associated inter-turbine duct/strut segment. The simulations are designed to resolve up to the second harmonic of the blade passing frequency tone in accordance with accepted rules for second order solvers like TURBO. The calculations include blade and vane cooling flows and a radial profile of pressure and temperature at the turbine inlet. The calculation can be modified later to include the combustor pattern factor at the
Energy Technology Data Exchange (ETDEWEB)
Trezza, M.; Cirillo, C.; Sabatino, P.; Carapella, G.; Attanasio, C. [CNR-SPIN Salerno and Dipartimento di Fisica “E. R. Caianiello”, Università degli Studi di Salerno, Fisciano I-84084 (Italy); Prischepa, S. L. [Belarusian State University of Informatics and Radioelectronics, P. Browka 6, Minsk 220013 (Belarus)
2013-12-16
We report on the transport properties of an array of N∼30 interconnected Nb nanowires, grown by sputtering on robust porous Si substrates. The analyzed system exhibits a broad resistive transition in zero magnetic field, H, and highly nonlinear V(I) characteristics as a function of H, which can be both consistently described by quantum tunneling of phase slips.
Karasawa, Yoshio; Vanmany, Changarkame
In order to evaluate the effect of Nakagami-Rice fading on Orthogonal Frequency Division Multiplex (OFDM) signal transmission when the delay profile exceeds the guard interval, a simple prediction model is developed by extending the Equivalent Transmission-Path (ETP) model for Rayleigh fading. The validity of the model is demonstrated by comparing the calculated values of BER to those obtained by computer simulation. Using the newly developed ETP-OFDM model, digital transmission characteristics of the OFDM signal in a multipath environment when the delay profile exceeds the guard interval are shown as a function of K factor, delay spread, guard interval and OFDM symbol period.
Institute of Scientific and Technical Information of China (English)
XU OU; LU ShaoHua; DONG XiaoWei; LI Bin; NING TiGang; JIAN ShuiSheng
2008-01-01
The characteristics of transmission spectra for the all fiber, multi-cavity FabryPerot (FP) configuration based on fiber Bragg gratings (FBG) are theoretically analyzed and modeled. The general transmission matrix function for the structure with any number of cavities is derived, and explicit expression of the power trans-mission coefficient for symmetrical two-cavity FP is presented. The general condi-tions for flat-top single resonant peak at the central wavelength in FBG stop band are derived and verified in the numerical simulation section. The transmission peaks of single-cavity and two-cavity FP structures are compared and discussed, and results show that compared to the single-cavity FP, flatness of the top and steepness at the edge of transmission peak can be improved by introducing one more cavity. The resonant transmission peak properties of two-cavity structure are investigated in detail for various values of cavity length and FBGs with different reflection characteristics, and the design guidelines for transmission-type filters are presented. The results show that the steepness of peak slope can be improved by increase of FBG reflectivities, and these kinds of filters can be used as nar-row-band single-channel selectors and multi-channel wavelength de-multiplexing by properly choosing the length of cavities and reflectivities of FBGs.
Energy Technology Data Exchange (ETDEWEB)
Zhu, Zhi-Wen [Department of Mechanics, Tianjin University, 92 Weijin Road, Nankai District, Tianjin 300072 (China); Tianjin Key Laboratory of Nonlinear Dynamics and Chaos Control 92 Weijin Road, Nankai District, Tianjin 300072 (China); Zhang, Qing-Xin [Department of Mechanics, Tianjin University, 92 Weijin Road, Nankai District, Tianjin 300072 (China); Xu, Jia, E-mail: xujia_ld@163.com [Department of Mechanics, Tianjin University, 92 Weijin Road, Nankai District, Tianjin 300072 (China)
2014-11-03
A kind of shape memory alloy (SMA) hysteretic nonlinear model was developed, and the nonlinear dynamics and bifurcation characteristics of the SMA thin film subjected to in-plane stochastic excitation were investigated. Van der Pol difference item was introduced to describe the hysteretic phenomena of the SMA strain–stress curves, and the nonlinear dynamic model of the SMA thin film subjected to in-plane stochastic excitation was developed. The conditions of global stochastic stability of the system were determined in singular boundary theory, and the probability density function of the system response was obtained. Finally, the conditions of stochastic Hopf bifurcation were analyzed. The results of theoretical analysis and numerical simulation indicate that self-excited vibration is induced by the hysteretic nonlinear characteristics of SMA, and stochastic Hopf bifurcation appears when the bifurcation parameter was changed; there are two limit cycles in the stationary probability density of the dynamic response of the system in some cases, which means that there are two vibration amplitudes whose probabilities are both very high, and jumping phenomena between the two vibration amplitudes appear with the change in conditions. The results obtained in this current paper are helpful for the application of the SMA thin film in stochastic vibration fields. - Highlights: • Hysteretic nonlinear model of shape memory alloy was developed. • Van der Pol item was introduced to interpret hysteretic strain–stress curves. • Nonlinear dynamic characteristics of the shape memory alloy film were analyzed. • Jumping phenomena were observed in the change of the parameters.
Nonlinear Resistor with Polynomial AV Characteristics and Its Application in Chaotic Oscillator
Directory of Open Access Journals (Sweden)
V. Pospisil
2004-06-01
Full Text Available This paper shows the realization of two terminal devices with anarbitrary polynomial nonlinearity up to the fifth order. The proposeddesign procedure is completely systematic using minimum of components.The very heart of our conception is four-channel four-quadrant analogmultiplier MLT04. The implementation of synthesized nonlinear resistoras a general nonlinearity in chaotic oscillator is also presented andexperimentally verified.
Zhou, Feifei; Fang, Keyan; Li, Yingjun; Chen, Qiuyan; Chen, Dan
2016-10-01
Hydroclimate variations in the mid-latitude Asia have received considerable attention due to its significance for the regional ecosystem and livelihood, while its nonlinear characteristics over the past centuries are not fully understood yet. Hydroclimate patterns for the mid-latitude Asia are classified into eastern and western modes based on a network of the reconstructed Palmer drought severity index (PDSI) of 197 grids spanning since 1300. The hydroclimate variations of western mode are more complex than that of eastern mode based on the Higuchi's fractal dimension (HFD) analysis, which may be related to the complex atmospheric circulation patterns that dominate them. The relationships of the hydroclimate variations between western and eastern modes at different time scales extracted by ensemble empirical mode decomposition method (EEMD) are detected. The anti-phase relationship of the hydroclimatic variations between western and eastern modes at the interdecadal variations occurs during the periods with the enhanced El Nino Southern Oscillation (ENSO) variance. Similarly, the multidecadal hydroclimate variations are anti-phase when the Pacific Decadal Oscillation (PDO) is in its warm phases. The inverse relationship between western and eastern modes is stable for the centennial scale.
Probability characteristics of nonlinear dynamical systems driven by δ -pulse noise
Dubkov, Alexander A.; Rudenko, Oleg V.; Gurbatov, Sergey N.
2016-06-01
For a nonlinear dynamical system described by the first-order differential equation with Poisson white noise having exponentially distributed amplitudes of δ pulses, some exact results for the stationary probability density function are derived from the Kolmogorov-Feller equation using the inverse differential operator. Specifically, we examine the "effect of normalization" of non-Gaussian noise by a linear system and the steady-state probability density function of particle velocity in the medium with Coulomb friction. Next, the general formulas for the probability distribution of the system perturbed by a non-Poisson δ -pulse train are derived using an analysis of system trajectories between stimuli. As an example, overdamped particle motion in the bistable quadratic-cubic potential under the action of the periodic δ -pulse train is analyzed in detail. The probability density function and the mean value of the particle position together with average characteristics of the first switching time from one stable state to another are found in the framework of the fast relaxation approximation.
Nonlinear friction characteristics between silica surfaces in high pH solution.
Taran, Elena; Kanda, Yoichi; Vakarelski, Ivan U; Higashitani, Ko
2007-03-15
Molecular-scale characteristics of friction forces between silica particles and silica wafers in aqueous solutions of the normal (pH 5.6) and high pH (pH 10.6) are investigated, using the lateral force measuring procedure of the atomic force microscope (AFM). Various significant differences of friction characteristics between solutions of normal and high pH's are found. In the case of solutions of normal pH, the friction force increases linearly with increasing loading force, as the Amonton's law for solid bodies indicates. However, in the case of high pH solutions, the increasing rate with the loading force is considerably reduced in the low loading region, but the value increases abruptly above a critical loading force to overcome the magnitude of friction force of normal pH above the region of very high loading. It is very interesting to know that this nonlinear force curve at high pH is independent of the atomic-scale roughness of surfaces, although the magnitude of friction is greatly influenced by the roughness in the case of normal pH. The reason why the friction at high pH is independent of the surface roughness is postulated to be due to the hairy-like layer formed on the silica surface. The existence of hairy-like layers at high pH is proven directly by the dynamic method of normal force measurements with AFM and the thickness is estimated to be at least ca. 1.3 nm.
Chandra, S.; Vardhanan, A. Vishnu; Gangopadhyay, R.
2007-11-01
Optical phase conjugation (OPC) and distributed Raman amplifier (DRA) combination (OPC-DRA) is demonstrated as a potential enabling solution for simultaneous reduction of fiber non-linearities and dispersion compensation of a sub-carrier multiplexed (SCM) optical transmission link. The present work is focused on the use of OPC-DRA combination for system performance improvement in terms of composite second order distortion (CSO) and carrier to noise ratio (CNR) of the SCM link. The analysis further shows that, introduction of DRA with proper pumping scheme significantly reduce fiber non-linearity resulting in improvement of the system performance in terms of CNR, compared to the situation where only mid-way optical phase conjugation is used.
Study on the effects of the space environment on laser transmission characteristics
Fu, Qiang; Liu, Peng; Tong, Shoufen; Zhang, Peng
2014-11-01
Laser space communication has obvious advantages in interstellar transmission - but the space environment will have a direct impact on laser communication system. The function of the analysis of space environment identity effectively could reduce and avoid the bug and invalidation produced by the overload to prolong the using span of effective load and increase the credibility of effective load, meanwhile it is also the main principle to design and research .This article summarizes the characteristics of vacuum space environment(Effect of vacuum outlet, Molecular contamination effect, Vacuum Mount, Cold welding effect, Heat radiation effect under vacuum), low temperature environment, background radiation (including space background radiation caused by thermal radiation, space background radiation caused by light noise). Space background radiation for the performance of space laser communication load is two aspects: one is the background of space radiation caused by thermal radiation, it mainly affects the satellite platform and payload of the thermal control design; Background spectrum caused by radiation and space, it will affect the space laser communication of the signal-to-noise ratio of the receiving unit, which affect the acquisition probability, tracking accuracy and error rate of communication, and particle radiation environment (Including total dose effects, single event effect), the plasma environment in five areas from the characteristics of space environment, for the problem of Space channel Influence the laser communication system performance. On this basis ,this article analysis the influence of space environment on the laser communication system with some examples, which will lay the foundation for the application of space laser communication system of our country.
Institute of Scientific and Technical Information of China (English)
侯景鹏; 陈加宝; 雷俊方
2012-01-01
With the 5A-ZM4 cat-head transmission tower as an example, a finite element model of transmission tower-line system consisting of two towers and three lines is established by using ANASYS software. The dynamic characteristics of natural frequencies and vibration modes of the system are calculated and the influencing factors are analyzed. Based on 3 typical seismic records of Tianjin wave, El-Centro wave and Shanghai artificial seismic wave, the peak values of the accelerations are scaled up to consider the nonlinear behaviors and plastic limit of transmission towers. The results show that the largest displacements on top of the tower are mainly concentrated between H/200-/100 (H is the height of tower) in the nonlinear ultimate limit state under earthquake; and that the bars between the second and the third diaphragms of the tower fall first into elastic-plastic limit state and produce large plastic deformation, indicating a strong nonlinear characteristics of the system.%地震对输电塔线的安全运行产生了威胁.选择输电线路工程中常用的5A-ZM4猫头塔为研究对象,利用ANSYS软件建立两塔三线输电塔线体系有限元模型,计算塔线体系的自振频率和振型并分析影响其动力特性的主要因素.选用天津波、EI-Centro波、上海人工波3条典型地震波,通过调整加速度峰值的方法研究塔线体系的位移响应非线性行为以及弹塑性极限状态.分析结果表明,强震作用下塔线体系进入非线性极限状态时,塔顶最大位移主要集中在H/200～H/100(H为塔高)之间;塔身第2至第3横隔之间杆件将率先进入弹塑性极限状态,产生较大塑性变形,使体系表现出较强的非线性特征.
Channel Characteristics and Transmission Performance for Various Channel Configurations at 60 GHz
Directory of Open Access Journals (Sweden)
Haibing Yang
2007-05-01
Full Text Available Extensive measurements are conducted in room environments at 60 GHz to analyze the channel characteristics for various channel configurations. Channel parameters retrieved from measurements are presented and analyzed based on generic channel models. Particularly, a simple single-cluster model is applied for the parameter retrieval and performance evaluation. By this model, power delay profiles are simply described by a K-factor, a root-mean-squared delay spread, and a shape parameter. The considered channels are configured with the combination of omnidirectional, fan-beam, and pencil-beam antennas at transmitter and receiver sides. Both line-of-sight (LOS and non-LOS (NLOS channels are considered. Further, to evaluate the transmission performance, we analyze the link budget in the considered environments, then design and simulate an OFDM system with a data rate of 2 Gbps to compare the bit-error-rate (BER performance by using the measured and modeled channels. Both coded and uncoded OFDM systems are simulated. It is observed that the BER performance agrees well for the measured and modeled channels. In addition, directive configurations can provide sufficient link margins and BER performance for high data rate communications. To increase the coverage and performance in the NLOS area, it is preferable to apply directive antennas.
Nonlinear analysis of gravity signals based on estimating attractor topological characteristics
Minervina, H.
2003-04-01
The nonlinear dynamical systems (NDSs) and processes with self-organization named as complex systems[1] are investi- gated with great activity in last decades.The gravity phe- nomenon can be also interpreted from the point of view of the self-organization theory first of all as primary irre- versible process [1].The NDS behavior are described on the basis of reconstruction of its attractor in m-dimensional Euclidean state-space and estimation of attractor topolo- gical characteristics(including minimal embedding dimension, scaling factors etc). With this aim it is necessary to select the state-space with the minimal dimension m* as the value m* is an upper limit of the degrees of freedom for a system. The determing m* on the basis of various correlative topological methods requires large computer expenditures [2]. Such methods have essential computational complexity and demand long time series (N is approximatly equal to 10000 - 100000 points) for their implementation. The method proposed in [3]-[5] allows to reduce the compu- tational complexity. However,the proposed locally topolo- gical method has especially heuristic character.This paper gives the theoretical ground of a local-topological method for defining minimal attractor embedding dimension on the basis of proposed matrix series into the state-space [6]. This method requires much less experimental data and is stable to changing m* [3],[5].The investigation of digital gravity signals using local-topological analysis of chaotic attractor trajectories is carried out. For this case we use the geodynamic ground of monotoring for observing variations of gravity field of the Earth on the base of quartz gravi- meters as GNU-KS. The computer confirmation of the theore- tical results is presented. References [1] G.Nicolis and I.Prigogine. Exploring Complexity. W.H.Freeman and Co., New York, 1989. [2] P.Grassberger and I. Procaccia,Characterization of strange attractors, Phys. Rev.Lett. vol.50, 346-349,1983. [3] V
Goot, van der J.A.; Jong, de M.C.M.; Koch, G.; Boven, van R.M.
2003-01-01
Low pathogenicity avian influenza A strains (LPAI) of the H5 and H7 type are noted for their ability to transform into highly pathogenic counterparts (HPAI). Here we compare the transmission characteristics in poultry of LPAI H5N2 (A/Chicken/Pennsylvania/83) and corresponding HPAI virus by means of
Energy Technology Data Exchange (ETDEWEB)
Nageshwari, M.; Jayaprakash, P.; Kumari, C. Rathika Thaya [PG & Research Department of Physics, Arignar Anna Govt. Arts College, Cheyyar 604407, Tamil Nadu (India); Vinitha, G. [Department of Physics, School of Advanced Sciences, VIT Chennai, 600127 Tamil Nadu (India); Caroline, M. Lydia, E-mail: lydiacaroline2006@yahoo.co.in [PG & Research Department of Physics, Arignar Anna Govt. Arts College, Cheyyar 604407, Tamil Nadu (India)
2017-04-15
An efficient nonlinear optical semiorganic material L-valinium L-valine chloride (LVVCl) was synthesized and grown-up by means of slow evaporation process. Single crystal XRD evince that LVVCl corresponds to monoclinic system having acentric space group P2{sub 1}. The diverse functional groups existing in LVVCl were discovered with FTIR spectral investigation. The UV-Visible and photoluminescence spectrum discloses the optical and electronic properties respectively for the grown crystal. Several optical properties specifically extinction coefficient, reflectance, linear refractive index, electrical and optical conductivity were also determined. The SEM analysis was also carried out and it portrayed the surface morphology of LVVCl. The calculated value of laser damage threshold was 2.59 GW/cm{sup 2}. The mechanical and dielectric property of LVVCl was investigated employing microhardness and dielectric studies. The second and third order nonlinear optical characteristics of LVVCl was characterized utilizing Kurtz Perry and Z scan technique respectively clearly suggest its suitability in the domain of optics and photonics. - Graphical abstract: Good quality transparent single crystals of L-valinium L-valine chloride single crystal was grown by slow evaporation technique. The grown crystals were analyzed using different instrumentation methods to check its usefulness for the device fabrication. The determination of nonlinear refractive index (n{sub 2}), absorption coefficient (β) and third order nonlinear susceptibility was determined by Z scan technique, highlighted that LVVCl can serve as a promising candidate for opto electronic and nonlinear optical applications.
Directory of Open Access Journals (Sweden)
Yuhwai Tseng
Full Text Available Intra-body communication is a new wireless scheme for transmitting signals through the human body. Understanding the transmission characteristics of the human body is therefore becoming increasingly important. Electrostatic-coupling intra-body communication system in a ground-free situation that integrate electronic products that are discretely located on individuals, such as mobile phones, PDAs, wearable computers, and biomedical sensors, are of particular interest.The human body is modeled as a simplified Resistor-Capacitor network. A virtual ground between the transmitter and receiver in the system is represented by a resister-capacitor network. Value of its resistance and capacitance are determined from a system perspective. The system is characterized by using a mathematical unit step function in digital baseband transmission scheme with and without Manchester code. As a result, the signal-to-noise and to-intersymbol-interference ratios are improved by manipulating the load resistor. The data transmission rate of the system is optimized. A battery-powered transmitter and receiver are developed to validate the proposal.A ground-free system fade signal energy especially for a low-frequency signal limited system transmission rate. The system transmission rate is maximized by simply manipulating the load resistor. Experimental results demonstrate that for a load resistance of 10k-50k Ω, the high-pass 3 dB frequency of the band-pass channel is 400kHz-2MHz in the worst-case scenario. The system allows a Manchester-coded baseband signal to be transmitted at speeds of up to 20M bit per second with signal-to-noise and signal-to-intersymbol-interference ratio of more than 10 dB.The human body can function as a high speed transmission medium with a data transmission rate of 20Mbps in an electrostatic-coupling intra-body communication system. Therefore, a wideband signal can be transmitted directly through the human body with a good signal
A Study on the Characteristics of the Transmission of Images of Tibet on the Internet
Institute of Scientific and Technical Information of China (English)
WANG Wanhong
2014-01-01
The internet has increasingly be-come a new important media in our lives , and it also brings new challenges and opportunities for the transmission of Tibetan culture-of which the images of Tibet on the internet play an extremely important role.Internet images, i.e.the digital images and videos uploaded onto the internet , have be-come another kind of major text-the text of images or pictorial text .It is the pictorial text that pres-ents visually the mysterious Tibetan culture in cy-berspace , and enables everyone to have a closer look at the truth and miracle of the Qinghai-Tibet high plateau .At present , there are a large num-ber of images and videos related to Tibet on the in-ternet , and the graphical trend of Tibetan internet culture is obvious .While internet images dissemi-nate Tibetan culture to the world , they also reflect its characteristics which differ from traditional ima-ges and the written text. 1) The Ease in obtaining (the images).The easiness refers to the “ease in obtaining andannouncing” with the help of digital techniques forphotography and internet.Firstly, based on digitaltechniques, no matter whether it is a digitalcamera, smartphone or tablet PC, all are equippedwith not less than 2 million or even 5 millionpixel camera lenses, which enable digital imagesof Tibet to exist everywhere.Secondly, theTibet Autonomous Region has built a communicationsnetwork which covers all cities, counties,towns and important traffic hubs and tourist attractionsin Tibet.Finally, speaking from the perspectiveof photographers, there are official mediaphotographers, ordinary people, event participantsand visitors in Tibetan areas.All of themcan use cameras and mobile phones to record thepeople, events, and landscape of Tibet, and uploadthese images onto the internet.These form aspectacular landscape of images that everyone canshare. 2) The Ease in Editing (PS).Internet imagesare different from the paper images.Becauseof their digital technical
Energy Technology Data Exchange (ETDEWEB)
Geniet, F; Leon, J [Physique Mathematique et Theorique, CNRS-UMR 5825, 34095 Montpellier (France)
2003-05-07
A nonlinear system possessing a natural forbidden band gap can transmit energy of a signal with a frequency in the gap, as recently shown for a nonlinear chain of coupled pendulums (Geniet and Leon 2002 Phys. Rev. Lett. 89 134102). This process of nonlinear supratransmission, occurring at a threshold that is exactly predictable in many cases, is shown to have a simple experimental realization with a mechanical chain of pendulums coupled by a coil spring. It is then analysed in more detail. First we go to different (nonintegrable) systems which do sustain nonlinear supratransmission. Then a Josephson transmission line (a one-dimensional array of short Josephson junctions coupled through superconducting wires) is shown to also sustain nonlinear supratransmission, though being related to a different class of boundary conditions, and despite the presence of damping, finiteness, and discreteness. Finally, the mechanism at the origin of nonlinear supratransmission is found to be a nonlinear instability, and this is briefly discussed here.
Institute of Scientific and Technical Information of China (English)
Xia Ji; Wei Cai; Pingwen Zhang
2008-01-01
In this paper, we analyze the transmission and reflection properties of a high order discontinuous Galerkin method for dispersive Maxwell's equations, originally proposed by Lu et al. [J. Comput. Phys. 200 (2004), pp. 549-580]. We study the reflection and transmission properties of the numerical method for up to second-order polynomial elements for one-and two-dimensional Maxwell's equations with rectangular meshes. High order accuracy has been shown for reflection and transmission coefficients near material interfaces.
Zheng, Guangtai; Qiu, Yi; Griffin, Michael J.
2012-12-01
The vertical apparent mass of the human body exhibits nonlinearity, with the principal resonance frequency reducing as the vibration magnitude increases. Measures of the transmission of vibration to the spine and the pelvis have suggested complex modes are responsible for the dominant resonance during vertical excitation, but the modes present with dual-axis excitation have not been investigated. This study was designed to examine how the apparent mass and transmissibility of the human body depend on the magnitude of vertical excitation and the addition of fore-and-aft excitation, and the relation between the apparent mass and the transmissibility of the body. The movement of the body (over the first, fifth and twelfth thoracic vertebrae, the third lumbar vertebra, and the pelvis) in the fore-and-aft and vertical directions (and in pitch at the pelvis) was measured in 12 male subjects sitting with their hands on their laps during random vertical vibration excitation (over the range 0.25-20 Hz) at three vibration magnitudes (0.25, 0.5 and 1.0 m s-2 rms). At the highest magnitude of vertical excitation (1.0 m s-2 rms) the effect of adding fore-aft vibration (at 0.25, 0.5, and 1.0 m s-2 rms) was investigated. The forces in the vertical and fore-and-aft directions on the seat surface were also measured so as to calculate apparent masses. Resonances in the apparent mass and transmissibility to the spine and pelvis in the fore-and-aft and vertical directions, and pitch transmissibility to the pelvis, shifted to lower frequencies as the magnitude of vertical excitation increased and as the magnitude of the additional fore-and-aft excitation increased. The nonlinear resonant behaviour of the apparent mass and transmissibility during dual-axis vibration excitation suggests coupling between the principal mode associated with vertical excitation and the cross-axis influence of fore-and-aft excitation. The transmissibility measures are consistent with complex modes
Characteristic analysis of liquid forced nonlinear sloshing under low-gravity
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
Under low gravity, the Lagrange equations in the form of volume integration of pressure of nonlinear liquid sloshing were built by variational principle. Based on this, the analytical solution of nonlinear liquid sloshing in pitching tank could be investigated. Then the velocity potential function was expanded in series by wave height function at the free surface so that the nonlinear equations with kinematics and dynamics free surface boundary conditions were derived. Finally, these nonlinear equations were investigated analytically by the multiple scales method. The result indicates that the system's amplitude-frequency response changes from 'softsping' to 'hard-spring' in the planar motion with the decresing of the Bond number, while in changes from 'hard-sping' to 'soft-spring' in the rotary motion.
Institute of Scientific and Technical Information of China (English)
陈化; 罗壮初
2002-01-01
In this paper the authors study a class of non-linear singular partial differential equation in complex domain Ct × Cnx. Under certain assumptions, they prove the existence and uniqueness of holomorphic solution near origin of Ct × Cnx.
80 Gb/s transmission over 80 km and demultiplexing using a highly non-linear photonic crystal fibre
DEFF Research Database (Denmark)
Berg, Kim Skaalum; Oxenløwe, Leif Katsuo; Siahlo, Andrei;
2002-01-01
We report on, transmission of an 80 Gb/s signal over 80 km of standard single mode fibre with subsequent demultiplexing to 10 Gb/s in a NOLM containing a novel photonic crystal fibre......We report on, transmission of an 80 Gb/s signal over 80 km of standard single mode fibre with subsequent demultiplexing to 10 Gb/s in a NOLM containing a novel photonic crystal fibre...
Directory of Open Access Journals (Sweden)
Kunpeng Ji
2015-01-01
Full Text Available More ice deposits accreted on conductors or ground wires may be shed off when an overhead electric transmission line is responding to shocks initiated by natural ice shedding. Ice shedding causes the global mass, stiffness, and damping of the tower-line system to vary with time, and the successive shedding effect beyond a trigger event has not been taken into account in previous studies due to the lack of an adequate ice detachment model. In this paper, the ice shedding effect induced by initial shocks was considered in finite element (FE analysis. An ice detachment criterion, in the way of user-defined element rupture subroutine, was implemented into the main commercial nonlinear FE program ADINA, making it possible to consider the induced-ice-shedding effect numerically. The incremental FE form of the system’s governing equations of motion is presented where the variations in the mass and stiffness matrices of the system are taken into consideration. Taking a transmission line section following natural ice shedding as a case study, the results indicate that neglecting successive ice shedding underestimates the adverse influence of natural ice shedding. The proposed method can help to improve the design and evaluation of transmission lines in cold regions and to ensure their mechanical security.
Energy Technology Data Exchange (ETDEWEB)
Il' ichev, N N; Pashinin, P P; Gulyamova, E S; Bufetova, G A [A M Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation); Shapkin, P V; Nasibov, A S [P N Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)
2014-03-28
The linear and nonlinear transmission of Fe{sup 2+}:ZnSe crystals is measured at a wavelength of 2940 nm in the temperature range 20 – 220 °C. It is found that, with increasing temperature from 20 °C to 150 – 220 °C, the transmission of Fe{sup 2+}:ZnSe crystals decreases in the case of incident radiation with an intensity of ∼5.5 MW cm{sup -2} and increases in the case of radiation with an intensity of 28 kW cm{sup -2}. At a temperature of 220 °C, the linear transmission almost coincides with the nonlinear transmission. The transmission spectra of Fe{sup 2+}:ZnSe crystals at temperatures of 22 and 220 °C in the wavelength range 500 – 7000 nm are presented. (active media)
Shih, C. C.
1973-01-01
In order to establish a foundation of scaling laws for the highly nonlinear waves associated with the launch vehicle, the basic knowledge of the relationships among the paramaters pertinent to the energy dissipation process associated with the propagation of nonlinear pressure waves in thermoviscous media is required. The problem of interest is to experimentally investigate the temporal and spacial velocity profiles of fluid flow in a 3-inch open-end pipe of various lengths, produced by the propagation of nonlinear pressure waves for various diaphragm burst pressures of a pressure wave generator. As a result, temporal and spacial characteristics of wave propagation for a parametric set of nonlinear pressure waves in the pipe containing air under atmospheric conditions were determined. Velocity measurements at five sections along the pipes of up to 210 ft. in length were made with hot-film anemometers for five pressure waves produced by a piston. The piston was derived with diaphragm burst pressures at 20, 40, 60, 80 and 100 psi in the driver chamber of the pressure wave generator.
Directory of Open Access Journals (Sweden)
Lulla Opatowski
2011-09-01
Full Text Available While in Northern hemisphere countries, the pandemic H1N1 virus (H1N1pdm was introduced outside of the typical influenza season, Southern hemisphere countries experienced a single wave of transmission during their 2009 winter season. This provides a unique opportunity to compare the spread of a single virus in different countries and study the factors influencing its transmission. Here, we estimate and compare transmission characteristics of H1N1pdm for eight Southern hemisphere countries/states: Argentina, Australia, Bolivia, Brazil, Chile, New Zealand, South Africa and Victoria (Australia. Weekly incidence of cases and age-distribution of cumulative cases were extracted from public reports of countries' surveillance systems. Estimates of the reproduction numbers, R(0, empirically derived from the country-epidemics' early exponential phase, were positively associated with the proportion of children in the populations (p = 0.004. To explore the role of demography in explaining differences in transmission intensity, we then fitted a dynamic age-structured model of influenza transmission to available incidence data for each country independently, and for all the countries simultaneously. Posterior median estimates of R₀ ranged 1.2-1.8 for the country-specific fits, and 1.29-1.47 for the global fits. Corresponding estimates for overall attack-rate were in the range 20-50%. All model fits indicated a significant decrease in susceptibility to infection with age. These results confirm the transmissibility of the 2009 H1N1 pandemic virus was relatively low compared with past pandemics. The pattern of age-dependent susceptibility found confirms that older populations had substantial--though partial--pre-existing immunity, presumably due to exposure to heterologous influenza strains. Our analysis indicates that between-country-differences in transmission were at least partly due to differences in population demography.
Directory of Open Access Journals (Sweden)
Bo Wang
2014-01-01
Full Text Available When predicting the nonlinear stability of high-speed spindle system, it is necessary to create an accurate model that reflects the dynamic characteristics of the whole system, including the spindle-bearing joint and spindle-holder-tool joints. In this paper, the distribution spring model of spindle-holder-tool joints was built with the consideration of its dynamic characteristics; the five-DOF dynamic model of the angle contact ball bearing was also established to study the influence of speed and preload on the spindle-bearing joint, both of which were used in the general whole complete spindle system FEM model. The rationality of the model was verified by comparison with the FRF of traditional rigid model and experiments. At last, the influences of speed and cutting force on the nonlinear stability were analyzed by amplitude spectrum, bifurcation, and Poincaré mapping. The results provided a theoretical basis and an evaluating criterion for nonlinear stability prediction and product surface quality improvement.
Fonseca, Daniel; Cartaxo, Adolfo V. T.; Monteiro, Paulo P.
2007-06-01
The impact of the extinction ratio (ER) on the performance of a 40-Gb/s return-to-zero transmission system over standard single-mode fiber (SSMF) is presented. Several dispersion maps are analyzed in order to minimize the distortion due to the intrachannel nonlinear effects, namely, intrachannel cross-phase modulation and intrachannel four wave mixing (IFWM). The decrease of the ER until a specific value leads to an increase of the intensity distortion, which is mainly due to IFWM. As a consequence, two distinct transmission regimes are identified, depending on the input average power of each section and the ER of the optical signals. The first regime has previously been called the pseudolinear regime in the literature and occurs when high ERs are considered. The optimum dispersion map of this regime has a given optical precompensation and a total residual dispersion near zero. The second regime occurs with the decrease of the ER. Under such a circumstance, the optimum dispersion map obtained in the pseudolinear regime leads to significant degradation, which is mainly due to ghost pulses appearing in the symbol “0.” This effect can be reduced by a system with residual dispersion that is significantly different from zero, leading to a detected eye pattern with low degradation in the symbol “0” but high timing jitter, which limits the use of such signals in feasible transmission systems. We call this new regime pseudosolitonic as the intrachannel nonlinear effects are apparently reduced by the residual group velocity dispersion (as it is observed in the solitonic regime occurring at lower bit rates), but strong waveform degradation occurs along the SSMF transmission. The exact value of ER for which the change between the two transmission regimes is observed depends on the optical average power at the input of each section. A simple expression to predict the system conditions (namely, ER, input average power of each section, and number of sections) for which
A Symmetric Characteristic Finite Volume Element Scheme for Nonlinear Convection-Diffusion Problems
Institute of Scientific and Technical Information of China (English)
Min Yang; Yi-rang Yuan
2008-01-01
In this paper, we implement alternating direction strategy and construct a symmetric FVE scheme for nonlinear convection-diffusion problems. Comparing to general FVE methods, our method has two advantages. First, the coefficient matrices of the discrete schemes will be symmetric even for nonlinear problems.Second, since the solution of the algebraic equations at each time step can be inverted into the solution of several one-dimensional problems, the amount of computation work is smaller. We prove the optimal H1-norm error estimates of order O(△t2 + h) and present some numerical examples at the end of the paper.
Peri-implantitis: a complex condition with non-linear characteristics
Papantonopoulos, G.H.; Gogos, C.; Housos, E.; Bountis, T.; Loos, B.G.
2015-01-01
Aim To cluster peri-implantitis patients and explore non-linear patterns in peri-implant bone levels. Materials and Methods Clinical and radiographic variables were retrieved from 94 implant-treated patients (340 implants, mean 7.1 ± 4.1 years in function). Kernel probability density estimations on
Some examples of non-linear systems and characteristics of their solutions
CSIR Research Space (South Africa)
Greben, JM
2006-07-01
Full Text Available . In contrast to certain other applications in complexity theory, these non-linear solutions are characterized by great stability. To go beyond the dominant non-perturbative solution one has to consider the source term as well. The parameter freedom...
Peri-implantitis: a complex condition with non-linear characteristics
Papantonopoulos, G.H.; Gogos, C.; Housos, E.; Bountis, T.; Loos, B.G.
2015-01-01
Aim To cluster peri-implantitis patients and explore non-linear patterns in peri-implant bone levels. Materials and Methods Clinical and radiographic variables were retrieved from 94 implant-treated patients (340 implants, mean 7.1 ± 4.1 years in function). Kernel probability density estimations on
STUDY ON THE VIBRATION CHARACTERISTIC OF THE METAL PUSHING BELT CONTINUOUSLY VARIABLE TRANSMISSION
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
The solid and finite element model of metal pushing type continuously variable transmission are established at speed ratio of i=0.5 and i=2.0.In order to solve the problem of the complicated of structure,the node-node rod discrete finite element model is put forward and the whole system is simplified and established.The natural frequency and mode shape of system are solved by iterative Lanczos-reduce method for sensitivity analysis in finite element model.The new method and the result can be used to improve the smoothness of the variable transmission system and to propose the theory for reducing noise at operation.
Wei, Jiao; Lu, Huadong; Jin, Pixian; Peng, Kunchi
2017-02-20
A method of evaluating the thermal focal length of nonlinear crystal via transmission spectrum of a swept cavity (TSSC) is presented. By recording the resonant point offset of the TSSC, the thermal focal length can be successfully measured. Furtherly, by distinguishing the absorption of ultraviolet (UV) laser and UV laser induced infrared absorption (ULIIRA), it is clear that the ULIIRA is the important factor which induces the thermal lens effect compared to the absorption of UV laser for MgO-doped periodically poled stoichiometric lithium tantalate (MgO:PPSLT) crystal and it becomes serious with the increase of the generated UV laser. The ULIIRA coefficient measurement and thermal focal length evalution of MgO:PPSLT crystal can supply an useful reference for researchers to generate high quality UV laser and squeezed or entangled state of optical field by using MgO:PPSLT crystal. The presented method can also be used to precisely evaluate the thermal focal length of other nonlinear crystals.
Energy Technology Data Exchange (ETDEWEB)
Duan, J; Shen, S; Wu, X; Popple, R; Cardan, R; Huang, M; Tannazi, F; Brezovich, I [Univ Alabama Birmingham, Birmingham, AL (United States)
2015-06-15
Purpose: To quantified the dosimetric characteristics of a Calypso compatible radiotherapy couch using continuously scanned transmission factor as a function of gantry angle. Methods: Radiation dose as a function of gantry angle was measured with an ionization chamber at the center of a 30 cm diameter cylindrical phantom placed on Qfix kVue Calypso compatible couch. A 3-D scanner was employed to continuously scan the dose during an arc rotation delivery. Nearly continuous transmission curves of 0.03° step size were obtained from IEC gantry angle 90° to180° for 6 MV and 15 MV photon beams at three couch longitudinal positions (due to longitudinally non-uniform shape of the couch rails) with rails both at the center and on sides. The transmission curves were evaluated to assess the attenuation by the couch. They were also compared to those of a carbon fiber couch top. Results: The scanned transmission curves of the Calypso comptible couch showed fine details of the couch transmission as a function of gantry angle. The attenuation by the couch varied from 2.4% to 12.9% for the 6 MV photo beam and from 1.8% to 8.9% for the 15 MV photon beam depending on the gantry angle. The attenuation by the flat couch top is only approximately 2 to 3%, but by the rail is much more significant. Because the rails are not uniformly shaped in the longitudinal direction, attenuation by the rail for the same gantry angle varied with the rail longitudinal position. The transmission curves of the carbon fiber couch top are nearly identical to those of the Calypso compatible couch top. Conclusion: The Calypso compatible couch attenuates radiation by 2.4%–12.9% and 1.8%–8.9% for 6 MV and 15 MV photon beams, respectively. The attenuation by the rails is much more significant than the flat couch top.
Institute of Scientific and Technical Information of China (English)
Hongwei Li⁎; Junpeng Liu; Yunlong Zhou; Bin Sun
2016-01-01
Gas–liquid two-phase flow is complex and has uncertainty in phase interfaces, which make the two-phase flow look very complicated. Even though the flow behavior (e.g. coalescence, crushing and separation) of single bubble or bubble groups in the liquid phase looks random, combining some established character-istics and methodologies can find regularities among the randomness. In order to excavate the nonlinear dynamic characteristics of gas–liquid two-phase flow, the authors developed an improved matrix pencil (IMP) method to analyze the pressure difference signals of the two-phase flow. This paper elucidates the influence of signal length on MP calculation results and the anti-noise-interference ability of the MP method. An IMP algorithm was applied to the fluctuation signals of gas–liquid two-phase flow to extract the mode frequency and damping ratio, which were combined with the component energy index (CEI) en-tropy to identify the different flow patterns. It is also found that frequency, damping ratio, CEI entropy and stability diagram together not only identify flow patterns, but also provide a new way to examine and un-derstand the evolution mechanism of physical dynamics embedded in flow patterns. Combining these characteristics and methods, the evolution of the nonlinear dynamic physical behavior of gas bubbles is revealed.
Arkharov, A. M.; Lavrov, N. A.; Romanovskii, V. R.
2014-06-01
The current instability is studied in high-temperature superconducting current-carrying elements with I- V characteristics described by power or exponential equations. Stability analysis of the macroscopic states is carried out in terms of a stationary zero-dimensional model. In linear temperature approximation criteria are derived that allow one to find the maximum allowable values of the induced current, induced electric field intensity, and overheating of the superconductor. A condition is formulated for the complete thermal stabilization of the superconducting composite with regard to the nonlinearity of its I- V characteristic. It is shown that both subcritical and supercritical stable states may arise. In the latter case, the current and electric field intensity are higher than the preset critical parameters of the superconductor. Conditions for these states depending on the properties of the matrix, superconductor's critical current, fill factor, and nonlinearity of the I- V characteristic are discussed. The obtained results considerably augment the class of allowable states for high-temperature superconductors: it is demonstrated that there exist stable resistive conditions from which superconductors cannot pass to the normal state even if the parameters of these conditions are supercritical.
Briley, Daniel A.; Harden, K. Paige; Tucker-Drob, Elliot M.
2014-01-01
Parents' expectations for their children's ultimate educational attainment have been hypothesized to play an instrumental role in socializing academically relevant child behaviors, beliefs, and abilities. In addition to social transmission of educationally relevant values from parents to children, parental expectations and child…
Far IR Transmission Characteristics of Silicon Nitride Films using Fourier Transform Spectroscopy
Ferrusca, D.; Castillo-Domínguez, E.; Velázquez, M.; Hughes, D.; Serrano, A.; Torres-Jácome, A.
2009-12-01
We are fabricating amorphous Silicon (a-Si) bolometers doped with boron with a measured NEP˜1.5×10-16 W/Hz1/2 suitable for use in millimeter and sub-millimeter astronomy. In this paper we present the preliminary results of the absorber optimization for the a-Si bolometers. A film of Silicon Nitride (SiN), deposited by LPCVD (Low Pressure Chemical Vapor Deposition) process at INAOE, with or without metallic coating is used as a weak thermal link to the heat sink as well as an absorber. We have measured the transmission spectrum of thin films of SiN in the range of 200 to 1000 GHz using Fourier Transform Spectroscopy (FTS) and a bolometric system with a NEP˜1.26×10-13. The transmission of thin films of SiN with a thickness of 0.4 μn has been measured at temperatures of 290 K and 4 K. The uncoated SiN films have a transmission of 80% and we expect a 50% transmission for the metallic (e.g. Titanium) coated films.
Directory of Open Access Journals (Sweden)
Hao Dong
2015-01-01
Full Text Available In order to implement the uniform load distribution of the power-split transmission system, a pseudostatic model is built. Based on the loaded tooth contact analysis (LTCA technique, the actual meshing process of each gear pair is simulated and the fitting curve of time-varying mesh stiffness is obtained. And then, the torsional angle deformation compatibility conditions are proposed according to the closed-loop characteristic of power flow, which will be combined with the torque equilibrium conditions and elastic support conditions to calculate the transfer torque of each gear pair. Finally, the load-sharing coefficient of the power-split transmission system is obtained, and the influences of the installation errors are analyzed. The results show that the above-mentioned installation errors comprehensively influence the load-sharing characteristics, and the reduction of only one error could not effectively achieve perfect load-sharing characteristics. Allowing for the spline clearance floating and constrained by the radial spacing ring, the influence of the floating pinion is analyzed. It shows that the floating pinion can improve the load-sharing characteristics. Through the comparison between the theoretical and related experimental data, the reasonability and feasibility of the above-proposed method and model are verified.
Geospatial characteristics of measles transmission in China during 2005-2014.
Yang, Wan; Wen, Liang; Li, Shen-Long; Chen, Kai; Zhang, Wen-Yi; Shaman, Jeffrey
2017-04-01
Measles is a highly contagious and severe disease. Despite mass vaccination, it remains a leading cause of death in children in developing regions, killing 114,900 globally in 2014. In 2006, China committed to eliminating measles by 2012; to this end, the country enhanced its mandatory vaccination programs and achieved vaccination rates reported above 95% by 2008. However, in spite of these efforts, during the last 3 years (2013-2015) China documented 27,695, 52,656, and 42,874 confirmed measles cases. How measles manages to spread in China-the world's largest population-in the mass vaccination era remains poorly understood. To address this conundrum and provide insights for future public health efforts, we analyze the geospatial pattern of measles transmission across China during 2005-2014. We map measles incidence and incidence rates for each of the 344 cities in mainland China, identify the key socioeconomic and demographic features associated with high disease burden, and identify transmission clusters based on the synchrony of outbreak cycles. Using hierarchical cluster analysis, we identify 21 epidemic clusters, of which 12 were cross-regional. The cross-regional clusters included more underdeveloped cities with large numbers of emigrants than would be expected by chance (p = 0.011; bootstrap sampling), indicating that cities in these clusters were likely linked by internal worker migration in response to uneven economic development. In contrast, cities in regional clusters were more likely to have high rates of minorities and high natural growth rates than would be expected by chance (p = 0.074; bootstrap sampling). Our findings suggest that multiple highly connected foci of measles transmission coexist in China and that migrant workers likely facilitate the transmission of measles across regions. This complex connection renders eradication of measles challenging in China despite its high overall vaccination coverage. Future immunization programs should
Robot Vibrations Caused by Torque Ripples in Power Transmission Mechanisms
小島, 宏行; 田口, 和哉; 辻, 浩明
1989-01-01
When an industrial robot with a power transmission mechanism such as a harmonic drive gear is operated, vibrations resulting from the torque ripple of the power transmission mechanism are frequently generated. However, few studies on robot vibration characteristics owing to torque ripples have been reported. In this paper, the vibrations of a horizontal two-link robot are investigated with consideration given to the torque ripple and the nonlinearity of the power transmission mechanism. In th...
Directory of Open Access Journals (Sweden)
Raicharan Denra
2016-12-01
Full Text Available In this paper, characteristics of small amplitude nonlinear dust acoustic wave have been investigated in a unmagnetized, collisionless, Lorentzian dusty plasma where electrons and ions are inertialess and modeled by generalized Lorentzian Kappa distribution. Dust grains are inertial and equilibrium dust charge is negative. Both adiabatic and nonadiabatic fluctuation of charges on dust grains have been taken under consideration. For adiabatic dust charge variation reductive perturbation analysis gives rise to a KdV equation that governs the nonlinear propagation of dust acoustic waves having soliton solutions. For nonadiabatic dust charge variation nonlinear propagation of dust acoustic wave obeys KdV-Burger equation and gives rise to dust acoustic shock waves. Numerical estimation for adiabatic grain charge variation shows the existence of rarefied soliton whose amplitude and width varies with grain charges. Amplitude and width of the soliton have been plotted for different electron Kappa indices keeping ion velocity distribution Maxwellian. For non adiabatic dust charge variation, ratio of the coefficients of Burger term and dispersion term have been plotted against charge fluctuation for different kappa indices. All these results approach to the results of Maxwellian plasma if both electron and ion kappa tends to infinity.
Kim, G.; Singh, R.
1995-01-01
Passive hydraulic mounts exhibit excitation frequency variant and deflection amplitude sensitive stiffness and damping properties. Such non-linear dynamic characteristics are examined by using analytical and experimental methods, both at the device level and within the context of a simplified vehicle model. A new lumped parameter non-linear mathematical model of the hydraulic mount is developed by simulating its decoupler switching mechanism and inertia track dynamics. The low frequency performance features and limitations of several passive mounts are made clear through the non-linear vehicle model simulation and comparable laboratory vibration tests. The high frequency performance problems of the passive hydraulic mount are identified by applying the quasi-linear analysis method. Based on these results, a new adaptive mount system is developed which exhibits broad bandwidth performance features up to 250 Hz. It implements an on-off damping control mode by using engine intake manifold vacuum and a microprocessor based solenoid valve controller. A laboratory bench set-up has already demonstrated its operational feasibility. Through analytical methods, it is observed that our adaptive mount provides superior dynamic performance to passive engine mounts and comparable performance to a small scale active mount over a wide frequency range, given the engine mounting resonance control, shock absorption and vibration isolation performance requirements. Although technical prospects of the proposed adaptive system appear promising, the in situperformance needs to be evaluated.
Denra, Raicharan; Paul, Samit; Sarkar, Susmita
2016-12-01
In this paper, characteristics of small amplitude nonlinear dust acoustic wave have been investigated in a unmagnetized, collisionless, Lorentzian dusty plasma where electrons and ions are inertialess and modeled by generalized Lorentzian Kappa distribution. Dust grains are inertial and equilibrium dust charge is negative. Both adiabatic and nonadiabatic fluctuation of charges on dust grains have been taken under consideration. For adiabatic dust charge variation reductive perturbation analysis gives rise to a KdV equation that governs the nonlinear propagation of dust acoustic waves having soliton solutions. For nonadiabatic dust charge variation nonlinear propagation of dust acoustic wave obeys KdV-Burger equation and gives rise to dust acoustic shock waves. Numerical estimation for adiabatic grain charge variation shows the existence of rarefied soliton whose amplitude and width varies with grain charges. Amplitude and width of the soliton have been plotted for different electron Kappa indices keeping ion velocity distribution Maxwellian. For non adiabatic dust charge variation, ratio of the coefficients of Burger term and dispersion term have been plotted against charge fluctuation for different kappa indices. All these results approach to the results of Maxwellian plasma if both electron and ion kappa tends to infinity.
Energy Technology Data Exchange (ETDEWEB)
Zhu, Z. W., E-mail: zhuzhiwen@tju.edu.cn [Department of Mechanics, Tianjin University, 300072, Tianjin (China); Tianjin Key Laboratory of Non-linear Dynamics and Chaos Control, 300072, Tianjin (China); Zhang, W. D., E-mail: zhangwenditju@126.com; Xu, J., E-mail: xujia-ld@163.com [Department of Mechanics, Tianjin University, 300072, Tianjin (China)
2014-03-15
The non-linear dynamic characteristics and optimal control of a giant magnetostrictive film (GMF) subjected to in-plane stochastic excitation were studied. Non-linear differential items were introduced to interpret the hysteretic phenomena of the GMF, and the non-linear dynamic model of the GMF subjected to in-plane stochastic excitation was developed. The stochastic stability was analysed, and the probability density function was obtained. The condition of stochastic Hopf bifurcation and noise-induced chaotic response were determined, and the fractal boundary of the system's safe basin was provided. The reliability function was solved from the backward Kolmogorov equation, and an optimal control strategy was proposed in the stochastic dynamic programming method. Numerical simulation shows that the system stability varies with the parameters, and stochastic Hopf bifurcation and chaos appear in the process; the area of the safe basin decreases when the noise intensifies, and the boundary of the safe basin becomes fractal; the system reliability improved through stochastic optimal control. Finally, the theoretical and numerical results were proved by experiments. The results are helpful in the engineering applications of GMF.
Nonlinear and Dissipation Characteristics of Ocean Surface Waves in Estuarine Environments
2010-01-01
determines the time scale over which the interactions occur, in the manner of Hill and Foda (1998) and Jamali et al. (2003). RESULTS Contrary to...the intermediate-depth work of Hill and Foda (1998) and Jamali et al. (2003), the interactions in this wealky-dispersive, weakly-nonlinear model...The stability of oscillatory internal waves. Journal of Fluid Mechanics, 30, 723-736. Hill, D.F., and Foda , M.A., 1998. Subharmonic resonance of
NONLINEAR DYNAMIC CHARACTERISTICS OF HYDRODYNAMIC JOURNAL BEARING-FLEXIBLE ROTOR SYSTEM
Institute of Scientific and Technical Information of China (English)
Lu Yanjun; Yu Lie; Liu Heng
2005-01-01
The nonlinear dynamic behaviors of flexible rotor system with hydrodynamic bearing supports are analyzed. The shaft is modeled by using the finite element method that takes the effect of inertia and shear into consideration. According to the nonlinearity of the hydrodynamic journal bearing-flexible rotor system, a modified modal synthesis technique with free-interface is represented to reduce degrees-of-freedom of model of the flexible rotor system. According to physical character of oil film, variational constrain approach is introduced to continuously revise the variational form of Reynolds equation at every step of dynamic integration and iteration. Fluid lubrication problem with Reynolds boundary is solved by the isoparametric finite element method without the increasing of computing efforts. Nonlinear oil film forces and their Jacobians are simultaneously calculated and -Newton-Floquet (PNF) method. A method, combining the predictor-corrector mechanism to the PNF method, is presented to calculate the bifurcation point of periodic motions to be subject to change of system parameters. The local stability and bifurcation behaviors of periodic motions are obtained by Floquet theory. The chaotic motions of the beating-rotor system are investigated by power spectrum.The numerical examples show that the scheme of this study saves computing efforts but also is of good precision.
微带线FDM特性传输特性分析%Microstrip line FDM transmission characteristics analysis
Institute of Scientific and Technical Information of China (English)
刘秉安; 刘青
2016-01-01
为了探讨微带线 FDM 特性传输特性，将 Matlab 应用于有限差分法的正演计算中，充分发挥了其强大而方便的功能。通过对二维稳定电流场模型的试算表明， Matlab 在研究微带线 FDM 特性传输特性方面有独特方便之处，利用它集数值分析、矩阵运算、信号处理和图形显示于一体，构成了一个方便的、界面和谐的优势，通过对维稳定电流场模型进行仿真实验，仿真结果恰好验证了 Matlab 在分析微带线 FDM 特性传输特性具有优势，且方法切实可行。%In order to explore transmission characteristics of microstrip line FDM, the Matlab was applied to forward modeling calculation of finite difference method, give full play to the function of its powerful and convenient. By the model of two-dimensional steady current field trial showed that the Matlab in studying the characteristics of microstrip line FDM has unique convenient transmission characteristics, use it to set numerical analysis, matrix computation, signal processing and graphic display at an organic whole, constitute a convenient, the advantages of harmonious interface, through the simulation experiment of d steady current field model, the simulation results to prove the Matlab FDM based on the analysis of microstrip line transmission characteristics method has advantages and practical.
Institute of Scientific and Technical Information of China (English)
Luo Zhi; Hao Zhiyong; Ni Dingrui; Zheng Xu
2015-01-01
AZ31B magnesium alloy was subjected to friction stir welding withvarious welding parameters. The equivalent Young’s moduli of the friction stir welded samples and the base material were obtained by the three-point method, and their transverse rigidities were obtained as well. Furthermore, the sound transmission characteristics of those samples were experimentally studied by four-microphone impedance tube method. The experimental results indicate that the transverse rigidities of the friction stir welded samples were only 79%, 83% and 92% of thoseof the base material, respectively. The sound transmission losses of the processed samples were also lower, which was largely due to the reduction of transverse rigidities induced by the decrease of equivalent Young’s moduli.
DEFF Research Database (Denmark)
Mweu, Marshal M.; Nielsen, Søren S.; Hisham Beshara Halasa, Tariq;
2012-01-01
-level incidence rates and apparent prevalences of Streptococcus agalactiae (S. agalactiae) in the population of Danish dairy cattle herds over a 10-year period from 2000 to 2009 inclusive and (2) to estimate the herd-level entry and exit rates (demographic parameters), the transmission parameter, β, and recovery......Contagious mastitis pathogens continue to pose an economic threat to the dairy industry. An understanding of their frequency and transmission dynamics is central to evaluating the effectiveness of control programmes. The objectives of this study were twofold: (1) to estimate the annual herd...... rate for S. agalactiae infection. Data covering the specified period, on bacteriological culture of all bulk tank milk samples collected annually as part of the mandatory Danish S. agalactiae surveillance scheme, were extracted from the Danish Cattle Database and subsequently analysed...
Nejati, Hamid
2013-01-01
We propose a closed form formulation for the impedance of the Metal-Insulator-Metal (MIM) plasmonic transmission lines by solving the Maxwell's equations. We provide approximations for thin and thick insulator layers sandwiched between metallic layers. In the case of very thin dielectric layer, the surface waves on both interfaces are strongly coupled resulting in an almost linear dependence of the impedance of the plasmonic transmission line on the thickness of the insulator layer. On the other hand, for very thick insulator layer, the impedance does not vary with the insulator layer thickness due to the weak-coupling/decoupling of the surface waves on each metal-insulator interface. We demonstrate the effectiveness of our proposed formulation using two test scenarios, namely, almost zero reflection in Tee-junction and reflection from line discontinuity in the design of Bragg reflectors, where we compare our formulation against previously published results.
Transmission characteristics of a bidirectional transparent screen based on reflective microlenses
Hedili, M. Kıvanç; Ürey, Hakan; Freeman, Mark O.
2013-01-01
A microlens array (MLA) based see-through, front projection screen, which can be used in direct projection head-up displays (HUD), color teleprompters and bidirectional interactive smart windows, is evaluated for various performance metrics in transmission mode. The screen structure consists of a partially reflective coated MLA buried between refractive-index-matched layers of epoxy as reported in Ref [1]. The reflected light is expanded by the MLA to create an eyebox for the user. The bright...
Institute of Scientific and Technical Information of China (English)
刘志峰; 蒋凤麒; 杨文通; 蔡力钢
2012-01-01
The transmission error is an important factor causing nonlinear vibration of cycloid bevel gear, and the vibration characteristics of gear system can be improved by prediction and calculation of the dynamic transmission error of cycloid bevel gear. The dynamic response characteristics of cycloid bevel gear were discussed under a range of operation speeds and acting torques. A new approach of surface integration and local FEM was proposed to solve the dynamic transmission error. And then, the strong nonlinear vibration characteristics of gear system were analysed. In the approach, it is no longer necessary to consider the nonlinear factors, such as the lime-varied stiffness and meshing frequency variation, as external excitations. However, in every lime step of gear meshing the dynamic mesh force and dynamic transmission error were calculated, and finally the nonlinear vibration characteristics of cycloid bevel gear were achieved. The approach can precisely present the key factors of the gear teeth, including the tooth geometry and tooth contact stress, which influence the dynamic characteristics of cycloid bevel gear significantly and provides an effective method for the analysis of complex vibration characteristics of cycloid bevel gear transmission system.%齿轮重载啮合中发生的轮齿接触损失会引起齿轮传动中的动态传递误差,动态传递误差的存在是等高齿锥齿轮非线性振动的重要原因,准确预测和计算等高齿锥齿轮传动中的动态传递误差是进一步改善这类齿轮系统振动特性的有效手段.针对某重载等高齿锥齿轮,研究其在一定运行速度和扭矩范围内的频率响应特性,运用一种新的曲面积分与局部有限元联合求解方法求解了等高齿锥齿轮传动中的动态传递误差,揭示出此类传动系统振动的强非线性特性.这种方法无需将时变拟合刚度和啮合频率变量等非线性因素作为外部的激励进行求解,而是从齿轮啮
Directory of Open Access Journals (Sweden)
Fei Chang
2015-01-01
Full Text Available The modular multilevel converter (MMC is an emerging voltage source converter topology suitable for multiterminal high voltage direct current transmission based on modular multilevel converter (MMC-MTDC. This paper presents fault characteristics of MMC-MTDC including submodule fault, DC line fault, and fault ride-through of wind farm integration. Meanwhile, the corresponding protection strategies are proposed. The correctness and effectiveness of the control strategies are verified by establishing a three-terminal MMC-MTDC system under the PSCAD/EMTDC electromagnetic transient simulation environment.
Effects of nonlinear sound propagation on the characteristic timbres of brass instruments.
Myers, Arnold; Pyle, Robert W; Gilbert, Joël; Campbell, D Murray; Chick, John P; Logie, Shona
2012-01-01
The capacity of a brass instrument to generate sounds with strong high-frequency components is dependent on the extent to which its bore profile supports nonlinear sound propagation. At high dynamic levels some instruments are readily sounded in a "cuivré" (brassy) manner: this phenomenon is due to the nonlinear propagation of sound in ducts of the proportions typical of labrosones (lip-reed aerophones). The effect is also evident at lower dynamic levels and contributes to the overall tonal character of the various kinds of brass instrument. This paper defines a brassiness potential parameter derived from the bore geometries of brass instruments. The correlation of the brassiness potential parameter with spectral enrichment as measured by the spectral centroid of the radiated sound is examined in playing tests using musicians, experiments using sine-wave excitation of instruments, and simulations using a computational tool. The complementary effects of absolute bore size on spectral enrichment are investigated using sine-wave excitation of cylindrical tubes and of instruments, establishing the existence of a trade-off between bore size and brassiness potential. The utility of the brassiness potential parameter in characterizing labrosones is established, and the graphical presentation of results in a 2D space defined by bore size and brassiness potential demonstrated.
Lederman, Edith R; Austin, Connie; Trevino, Ingrid; Reynolds, Mary G; Swanson, Holly; Cherry, Bryan; Ragsdale, Jennifer; Dunn, John; Meidl, Susan; Zhao, Hui; Li, Yu; Pue, Howard; Damon, Inger K
2007-08-01
Orf virus leads to self-limited, subacute cutaneous infections in children who have occupational or recreational contact with infected small ruminants. Breaches in the integument and contact with animals recently vaccinated for orf may be important risk factors in transmission. Common childhood behaviors are likely important factors in the provocation of significant contact (ie, bites) or in unusual lesion location (eg, facial lesions). Clinician recognition is important in distinguishing orf infection from life-threatening cutaneous zoonoses. Recently developed molecular techniques provide diagnostic precision and newer topical therapeutics may hasten healing.
A non-Linear transport model for determining shale rock characteristics
Ali, Iftikhar; Malik, Nadeem
2016-04-01
Unconventional hydrocarbon reservoirs consist of tight porous rocks which are characterised by nano-scale size porous networks with ultra-low permeability [1,2]. Transport of gas through them is not well understood at the present time, and realistic transport models are needed in order to determine rock properties and for estimating future gas pressure distribution in the reservoirs. Here, we consider a recently developed non-linear gas transport equation [3], ∂p-+ U ∂p- = D ∂2p-, t > 0, (1) ∂t ∂x ∂x2 complimented with suitable initial and boundary conditions, in order to determine shale rock properties such as the permeability K, the porosity φ and the tortuosity, τ. In our new model, the apparent convection velocity, U = U(p,px), and the apparent diffusivity D = D(p), are both highly non-linear functions of the pressure. The model incorporate various flow regimes (slip, surface diffusion, transition, continuum) based upon the Knudsen number Kn, and also includes Forchchiemers turbulence correction terms. In application, the model parameters and associated compressibility factors are fully pressure dependent, giving the model more realism than previous models. See [4]. Rock properties are determined by solving an inverse problem, with model parameters adjustment to minimise the error between the model simulation and available data. It is has been found that the proposed model performs better than previous models. Results and details of the model will be presented at the conference. Corresponding author: namalik@kfupm.edu.sa and nadeem_malik@cantab.net References [1] Cui, X., Bustin, A.M. and Bustin, R., "Measurements of gas permeability and diffusivity of tight reservoir rocks: different approaches and their applications", Geofluids 9, 208-223 (2009). [2] Chiba R., Fomin S., Chugunov V., Niibori Y. and Hashida T., "Numerical Simulation of Non Fickian Diffusion and Advection in a Fractured Porous Aquifer", AIP Conference Proceedings 898, 75 (2007
Nonlinear magnetic metamaterials.
Shadrivov, Ilya V; Kozyrev, Alexander B; van der Weide, Daniel W; Kivshar, Yuri S
2008-12-08
We study experimentally nonlinear tunable magnetic metamaterials operating at microwave frequencies. We fabricate the nonlinear metamaterial composed of double split-ring resonators where a varactor diode is introduced into each resonator so that the magnetic resonance can be tuned dynamically by varying the input power. We demonstrate that at higher powers the transmission of the metamaterial becomes power-dependent and, as a result, such metamaterial can demonstrate various nonlinear properties. In particular, we study experimentally the power-dependent shift of the transmission band and demonstrate nonlinearity-induced enhancement (or suppression) of wave transmission. (c) 2008 Optical Society of America
The non-linear characteristics in environmental system.%环境规划中的非线性特征
Institute of Scientific and Technical Information of China (English)
曾光明; B.Statzner; 等
2001-01-01
在实际环境规划中,很少考虑到非线性特征对环境投入的效益影响.以国内外目前主要3类水环境规划为例,研究了环境投入与环境改善之间的关系.对每一类环境规划,环境改善均随投入的增加而迅速减少.由于传统的环境管理或规划在选择下一种措施之前总是将大部分费用投入到前一种措施中,因此传统的环境管理或规划忽略了环境系统有关的非线性特征.应将有关费用投入以保证下一步措施获得最大的环境改善.与传统的环境管理或规划相比,这种考虑环境系统有关非线性特征影响的投入策略可以达到用较少的经费获得迅速的环境改善.%In practical environmental program, very little consideration has been given to the influence of non-linear characteristics on the benefit of environmental input. Using 3 main kinds of recently domestic or oversea program of water environment as examples, the relation of environmental input and environmental benefit was studied. For each of these programs, environmental improvement rapidly decreased with the increase of the input. In traditional environmental management or program, it was inevitable to invest important part of budget into a particular measure before choosing the next other measure. Thus, the non-linear characteristics related to environment system was ignored traditionally; and the related part of budget should be invested to ensure the achievement of the greatest environmental improvement in the measure of next step. Compared to traditional management, this alternating decision strategy considering the influence of non-linear characteristics related to environmental system will achieve rapid environmental improvements with less available budgets.
Two-Dimensional Tests of Wave Transmission and Reflection Characteristics of Laboratory Breakwaters.
1980-06-01
should be adjusted to KFC = - - 2C)- 0 and 1 on 15 fronting slope (16)R R Figures 17 and 18 illustrate the observed and predicted wave transmission...65. 1.69 1.0 .337 .337 .016 .0006 700301124. as. 1.69 0.3 .215 .sibs016 .0015 78103011131. 65. 1.41 9.6 .100 .100 .016 t00l0 76430211400 45. logo 13.6... logo 1. .391 .397 .016 .0020 78002631ft3. 35. 1.30 11.5 0862 .3A2 .001 .0069 7830eh610?. 35. 1.301 18.8 also o3’0 .021 .0069 780261236. 30. 2.17 7.7
Nageshwari, M.; Jayaprakash, P.; Kumari, C. Rathika Thaya; Vinitha, G.; Caroline, M. Lydia
2017-04-01
An efficient nonlinear optical semiorganic material L-valinium L-valine chloride (LVVCl) was synthesized and grown-up by means of slow evaporation process. Single crystal XRD evince that LVVCl corresponds to monoclinic system having acentric space group P21. The diverse functional groups existing in LVVCl were discovered with FTIR spectral investigation. The UV-Visible and photoluminescence spectrum discloses the optical and electronic properties respectively for the grown crystal. Several optical properties specifically extinction coefficient, reflectance, linear refractive index, electrical and optical conductivity were also determined. The SEM analysis was also carried out and it portrayed the surface morphology of LVVCl. The calculated value of laser damage threshold was 2.59 GW/cm2. The mechanical and dielectric property of LVVCl was investigated employing microhardness and dielectric studies. The second and third order nonlinear optical characteristics of LVVCl was characterized utilizing Kurtz Perry and Z scan technique respectively clearly suggest its suitability in the domain of optics and photonics.
Institute of Scientific and Technical Information of China (English)
Yonghan CHOI; Joowan KIM; Dong-Kyou LEE
2012-01-01
In this study,singular vectors related to a heavy rainfall case over the Korean Peninsula were calculated using the fifth-generation Pennsylvania State University-National Center for Atmospheric Research Mesoscale Model (MM5) adjoint modeling system.Tangent linear and adjoint models include moist physical processes,and a moist basic state and a moist total energy norm were used for the singular-vector calculations.The characteristics and nonlinear growth of the first singular vector were analyzed,focusing on the relationship between the basic state and the singular vector.The horizontal distribution of the initial singular vector was closely related to the baroclinicity index and the moisture availability of the basic state.The temperature-component energy at a lower level was dominant at the initial time,and the kinetic energy at upper levels became dominant at the final time in the energy profile of the singular vector.The nonlinear growth of the singular vector appropriately reflects the temporal variations in the basic state.The moisture-component energy at lower levels was dominant at earlier times,indicating continuous moisture transport in the basic state.There were a large amount of precipitation and corresponding latent heat release after that period because the continuous moisture transport created favorable conditions for both convective and nonconvective precipitation.The vertical propagation of the singular-vector energy was caused by precipitation and the corresponding latent heating in the basic state.
E Heebner, John; Boyd, Robert W; Park, Q-Han
2002-03-01
We describe an optical transmission line that consists of an array of wavelength-scale optical disk resonators coupled to an optical waveguide. Such a structure leads to exotic optical characteristics, including ultraslow group velocities of propagation, enhanced optical nonlinearities, and large dispersion with a controllable magnitude and sign. This device supports soliton propagation, which can be described by a generalized nonlinear Schrodinger equation.
Institute of Scientific and Technical Information of China (English)
黄毅; 刘辉; 项昌乐; 杨志刚
2014-01-01
随着对齿轮传动系统动态品质要求的提高，仅固有特性及其灵敏度的分析已经无法满足车辆传动系统动态特性分析的要求，对强迫振动下响应特性的灵敏度研究可为减振设计提供进一步的指导。研究非线性动力学响应对轴段扭转刚度、质量点惯量以及轮齿啮合误差的灵敏度。将某车辆传动系统样机作为研究对象，以发动机激励作为输入，建立平移扭转耦合集中参数动力学模型。模型中考虑时变啮合刚度、齿侧间隙、轮齿制造、安装误差以及质量偏心等非线性因素，通过直接求导法建立灵敏度方程，利用数值求解的方法获得动力学响应对设计参数的相对灵敏度并进一步将其转化成工程中有实际意义的物理量的灵敏度结果，为齿轮传动系统基于动态响应的参数修改、模型修正和参数优化等方面提供理论依据。%With increase in requirements of dynamic quality of a transmission system,only the eigensensitivities analysis can not meet the requirements of dynamic characteristics of a vehicle transmission system.It's needed to do response sensitivity study to find a guideline to reduce vibration of a vehicle transmission system in designing stage.Here, the sensitivities of dynamic response with respect to design parameters such as,shaft torsional stiffness,moment of inertia, and transmission errors of gear pairs,et al.were investigated.The translation-torsional coupled dynamic model of a vehicle transmission system taking engine excitation as an input source was built up with the lumped parameter method.The sensitivity equations were derived from dynamic equations containing nonlinear terms, such as, time-varying mesh stiffness,backlash of gear pairs,mass eccentricity,transmission error et al.The relative sensitivities of dynamic response with respect to design parameters then turned into relative sensitivities of force/torque with respect to design
Yashkir, O. V.; Yashkir, Yu N.
1987-06-01
A theoretical investigation is made of nonlinear excitation of planar waveguide modes at frequencies ω when external plane optical waves of frequency ω1 are incident on the waveguide surface. The general formulas for the efficiency of the excitation of modes by a monochromatic wave are obtained and analyzed for the case of self-interaction of the ω = ω1 + ω1 - ω1 type and by a biharmonic wave in the case of generation of the difference frequency ω = ω1 - ω1'. The efficiency of parametric conversion of waveguide modes ω accompanied by an increase of the frequency to the range ω' is considered for the case when the sum frequency ω + ω1 = ω1' is generated. The numerical method developed by the authors is used to analyze the characteristic features of these processes in some specific cases.
Arbitrary vehicle steering characteristics with changing ratio rack and pinion transmission
Directory of Open Access Journals (Sweden)
András G Bendefy
2015-12-01
Full Text Available In order to achieve arbitrary steering characteristics at vehicles, a steering mechanism was developed, in which changing ratio rack and pinion connections have been applied. In contrary to a regular steering mechanism where only a single rack is used, two racks were applied in order to make arbitrary characteristics possible. The turning wheel’s required motion functions had to be defined first, thereafter could we determine the changing ratio rack and pinion geometry which produces this motion. First, a simplified two-dimensional mockup was created in order to study the difficulties and possibilities of a real construction. Later, a fully functional assembly was designed and manufactured to make further experiments possible.
The characteristics of nonlinear chaotic dynamics in quantum cellular neural networks
Institute of Scientific and Technical Information of China (English)
Wang Sen; Cai Li; Kang Qiang; Wu Gang; Li Qin
2008-01-01
With the polarization of quantum-dot cell and quantum phase serving as state variables, this paper does both theoretical analysis and simulation for the complex nonlinear dynamical behaviour of a three-cell-coupled Quantum Cel- lular Neural Network (QCNN), including equilibrium points, bifurcation and chaotic behaviour. Different phenomena, such as quasi-periodic, chaotic and hyper-chaotic states as well as bifurcations are revealed. The system's bifurcation and chaotic behaviour under the influence of the different coupling parameters are analysed. And it finds that the unbalanced ceils coupled QCNN is easy to cause chaotic oscillation and the system response enters into chaotic state from quasi-periodic state by quasi-period bifurcation; however, the balanced cells coupled QCNN also can be chaotic when coupling parameters is in some region. Additionally, both the unbalanced and balanced cells coupled QCNNs can possess hyper-chaotic behaviour. It provides valuable information about QCNNs for future application in high-parallel signal processing and novel ultra-small chaotic generators.
Characteristic Extraction of Mental Disease Patients by Nonlinear Analysis of Plethysmograms
Hu, Yuyu; Wang, Wenbiao; Suzuki, Takashi; Oyama-Higa, Mayumi
2011-06-01
We measured the pulse waves of 196 mentally ill patients and 113 healthy students. Using heartbeat changes, we calculated the values of their sympathetic nerves, parasympathetic nerves, and autonomic nerve balance. In addition, we calculated the largest Lyapunov exponents (LLE) by non-linear analysis of plethysmograms. Values were analyzed by group. The results revealed a significant relationship between LLE and the autonomic nerve balance. The sympathetic nerve values in the patient group were significantly higher than those in the student group, whereas the LLE values were significantly lower. Furthermore, we illustrated the dynamic change in the results for single participants over several testing times. The measurement of pulse waves is easy and economical and does not put a strain on the subject. Additionally, these values can provide information that is more accurate than medical examination obtained from an interview. Our study contributed to the existing methodology in this field, and future data collection and measurement will be carried out. We hope that our study will be useful for neurologists and psychotherapists in their detection and treatment of mental illness.
Transmission characteristics of a bidirectional transparent screen based on reflective microlenses.
Hedili, M Kivanc; Freeman, Mark O; Urey, Hakan
2013-10-21
A microlens array (MLA) based see-through, front projection screen, which can be used in direct projection head-up displays (HUD), color teleprompters and bidirectional interactive smart windows, is evaluated for various performance metrics in transmission mode. The screen structure consists of a partially reflective coated MLA buried between refractive-index-matched layers of epoxy as reported in Ref [1]. The reflected light is expanded by the MLA to create an eyebox for the user. The brightness gain of the screen can be varied by changing the numerical aperture of the microlenses. Thus, using high gain designs, a low-power projector coupled with the screen can produce high-brightness and even 3D images as the polarization is maintained at the screen. The impact of the partially reflective coatings on the transmitted light in terms of resolution and modulation transfer function associated with the screen is studied. A condition similar to the Rayleigh criteria for diffraction-limited imaging is discussed for the microlens arrays and the associated coating layers. The optical path difference between the light transmitted from the center and the edges of each microlens caused by the reflective layer coatings should not exceed λ/4. Furthermore, the crosstalk between the front and rear projected images is found to be less than 1.3%.
Wu, Liang; Xiao, Ke; Dong, Jiaqi; Wang, Supin; Wan, Mingxi
2014-07-01
Understanding the sound transmission of the neck tissue is necessary and important in areas such as vocal function evaluation and electrolarynx improvement. In this paper, a simple method using a reflectionless tube was proposed to measure the neck frequency response function (NFRF) of ten normal subjects (five males and five females) during Mandarin vowel production. The NFRFs across different subjects producing different vowels were measured at different neck positions and compared to confirm the effectiveness of the method, and determine the NFRF variations in normal subjects. The results showed that the proposed method offered an easy and effective way to obtain an accurate NFRF. For normal subjects, the neck tissue can be treated as a low-pass filter, with a maximum gain at 310 Hz and a roll-off at a slope of -8.4 dB/octave, flattening out above 2000 Hz. The measurement position on the neck did not influence the shape of the NFRF, but did change the overall gains of the NFRF. In addition, there was a significant gender difference in NFRFs at the low frequencies. Finally, some potential applications of this method and the results are suggested.
Starks, Tyrel J.; Gamarel, Kristi E.; Johnson, Mallory O.
2014-01-01
Unprotected anal intercourse (UAI) remains a main risk factor for HIV among men who have sex with men (MSM) and this is of particular concern for partners of HIV serodiscordant status. However, HIV transmission risk has been demonstrated to vary by the sexual position adopted among partners. Guided by interdependence theory, this study examined how relational factors were differentially associated with risk taking (HIV-positive/insertive and HIV-negative/receptive) and strategic positioning (HIV-positive/receptive and HIV-negative/insertive) UAI withinserodiscordant same-sex male couples. HIV-positive men and their HIV-negative partners (ncouples=91; nindividuals=182) simultaneously but independently completed computerized questionnaires and HIV-positive men had blood drawn for viral load.A minority of couples (30%) engaged in risk taking and/or strategicpositioning unprotected anal sex. Results of multinomial logistic regressionindicated that HIV-negative partners’ levels of relationship commitment were positively associated with the odds of engaging in both risk taking and strategic positioning sexual behaviors. For HIV-negative partners, reports of relationship intimacy, autonomy, and sexual satisfaction were negatively associated with odds of reporting risk taking behavior. In contrast, HIV-positive partners’reported sexual satisfaction was positively associated with odds of engaging in risk taking behavior. Findings suggested that aspects of relational quality may be differentially associated with sexual decision making for same-sex male couples in serodiscordant relationships. Study findings lend support for the incorporation ofdiscussions of HIV risk reduction strategies, enhancing communication between partners, and support for general relationship functioning in HIV care. PMID:24243004
Starks, Tyrel J; Gamarel, Kristi E; Johnson, Mallory O
2014-01-01
Unprotected anal intercourse (UAI) remains a main risk factor for HIV among men who have sex with men (MSM) and this is of particular concern for partners of HIV serodiscordant status. However, HIV transmission risk has been demonstrated to vary by the sexual position adopted among partners. Guided by interdependence theory, this study examined how relational factors were differentially associated with risk taking (HIV-positive/insertive and HIV-negative/receptive) and strategic positioning (HIV-positive/receptive and HIV-negative/insertive) UAI within serodiscordant same-sex male couples. HIV-positive men and their HIV-negative partners (n couples = 91; n individuals = 182) simultaneously but independently completed computerized questionnaires and HIV-positive men had blood drawn for viral load. A minority of couples (30 %) engaged in risk taking and/or strategic positioning unprotected anal sex. Results of multinomial logistic regression indicated that HIV-negative partners' levels of relationship commitment were positively associated with the odds of engaging in strategic positioning sexual behaviors. For HIV-negative partners, reports of relationship intimacy, and sexual satisfaction were negatively associated with odds of reporting risk taking behavior. In contrast, HIV-positive partners' reported sexual satisfaction was positively associated with odds of engaging in risk taking behavior. Findings suggested that aspects of relational quality may be differentially associated with sexual decision making for same-sex male couples in serodiscordant relationships. Study findings lend support for the incorporation of discussions of HIV risk reduction strategies, enhancing communication between partners, and support for general relationship functioning in HIV care.
Directory of Open Access Journals (Sweden)
Chao Zhou
2017-01-01
Full Text Available Despite most weather-related failures of high-voltage transmission lines (HVTLs being attributed to the downbursts accompanied by heavy rainfall, research works mainly focused on the behaviors of the high-voltage transmission tower-line structures under dry downburst winds. This paper thus presents a preliminary study to discuss the characteristics of rainfall in the downbursts and their effects on responses of HVTLs. Based on Vicroy model, the velocities of raindrops and their loads and pressure ratios of downburst wind-driven rain and only downburst wind on the surface of HVTLs per unit length are obtained. A downburst wind-rain induced vibration model is established to calculate the effects of the rainfall intensity and wind velocities on the motions of HVTLs. To verify the feasibility and accuracy of the model, the model is applied to evaluate responses of HVTLs with measured aerodynamic coefficients. The responses of HVTLs from the evaluated (the model and the field observation results are compared. The results indicated that the model is feasible and can capture main features of the rainfall acting on HVTLs in the downbursts. Furthermore, the effects of rainfall cannot be neglected, and more attention should be paid to the wet downbursts and their effects on aerodynamic property of HVTLs.
Dean, P. D.; Salikuddin, M.; Ahuja, K. K.; Plumblee, H. E.; Mungur, P.
1979-01-01
The efficiency of internal noise radiation through a coannular exhaust nozzle with an inverted velocity profile was studied. A preliminary investigation was first undertaken (1) to define the test parameters which influence the internal noise radiation; (2) to develop a test methodology which could realistically be used to examine the effects of the test parameters; and (3) to validate this methodology. The result was the choice of an acoustic impulse as the internal noise source in the jet nozzles. Noise transmission characteristics of a coannular nozzle system were then investigated. In particular, the effects of fan convergence angle, core extension length to annulus height ratio and flow Mach numbers and temperatures were studied. Relevant spectral data only is presented in the form of normalized nozzle transfer function versus nondimensional frequency.
Institute of Scientific and Technical Information of China (English)
He Zhang; Jun Lu; Guancheng Sun; Hongliang Xiao
2008-01-01
Frequency-selective surface (FSS) is a two-dimensional periodic structure consisting of a dielectric substrate and the metal units (or apertures) arranged periodically on it. When manufacturing the substrate, its thickness and dielectric constant suffer process tolerances. This may induce the center frequency of the FSS to shift, and consequently influence its characteristics. In this paper, a bandpass FSS structure is designed. The units are the Jerusalem crosses arranged squarely. The mode-matching technique is used for simulation. The influence of the tolerances of the substrate's thickness and dielectric constant on the center frequency is analyzed. Results show that the tolerances of thickness and dielectric constant have different influences on the center frequency of the FSS. It is necessary to ensure the process tolerance of the dielectric constant in the design and manufacturing of the substrate in order to stabilize the center frequency.
Directory of Open Access Journals (Sweden)
Sakaros Bogning Dongue
2013-01-01
Full Text Available This paper presents the modelling of electrical I-V response of illuminated photovoltaic crystalline modules. As an alternative method to the linear five-parameter model, our strategy uses advantages of a nonlinear analytical five-point model to take into account the effects of nonlinear variations of current with respect to solar irradiance and of voltage with respect to cells temperature. We succeeded in this work to predict with great accuracy the I-V characteristics of monocrystalline shell SP75 and polycrystalline GESOLAR GE-P70 photovoltaic modules. The good comparison of our calculated results to experimental data provided by the modules manufacturers makes it possible to appreciate the contribution of taking into account the nonlinear effect of operating conditions data on I-V characteristics of photovoltaic modules.
Institute of Scientific and Technical Information of China (English)
DING Yujian; LIAO Weiming; SUN Zhaoying; SU Zhiyi
2011-01-01
The ± 1000 kV DC transmission line represents a new voltage level. In order to guarantee the design reliability and rationality, the air clearance selection is very important and needs to be researched. External insulation discharge characteristics of transmission lines are closely related to local atmospheric conditions. When the altitude increases, the air-gap discharge voltage will decrease as the air density decreases.
Yarmoghaddam, Elahe; Rakheja, Shaloo
2017-08-01
We theoretically model the dispersion characteristics of surface plasmons in a graphene-based parallel-plate waveguide geometry using nonlinear Kerr-type core (inter-plate) dielectric. The optical nonlinearity of graphene in the terahertz band under high light intensity is specifically included in the analysis. By solving Maxwell's equations and applying appropriate boundary conditions, we show that the waveguide supports four guided plasmon modes, each of which can be categorized as either symmetric or anti-symmetric based on the electric field distribution in the structure. Of the four guided modes, two modes are similar in characteristics to the modes obtained in the structure with linear graphene coating, while the two new modes have distinct characteristics as a result of the nonlinearity of graphene. We note that the group velocity of one of the plasmon modes acquires a negative value under high light intensity. Additionally, the optical nonlinearity of the core dielectric leads to a significant enhancement in the localization length of various plasmon modes. The description of the intra-band optical conductivity of graphene incorporates effects of carrier scatterings due to charged impurities, resonant scatterers, and acoustic phonons at 300 K. The proposed structure offers flexibility to tune the waveguide characteristics and the mode index by changing light intensity and electrochemical potential in graphene for reconfigurable plasmonic devices.
Virologic characteristics of hepatitis B virus in patients infected via maternal-fetal transmission
Institute of Scientific and Technical Information of China (English)
Tao Shen; Xin-Min Yan; Yun-Lian Zou; Jian-Mei Gao; Hong Dong
2008-01-01
AIM: To determine whether HBV with the same characteristics causes dissimilar mutations in different hosts.METHODS: Full-length HBV genome was amplified and linked with pMD T18 vector.Positive clones were selected by double-restriction endonuclease digestion (EcoR 1 and Hind Ⅲ) and PCR.Twenty seven clones were randomly selected from an asymptomatic mother [at two time points: 602 (1 d) and 6022 (6 mo)] and her son [602 (S)],and the phylogenetic and mutational analysis was performed using BioEditor,Clustal X and MEGA software.Potential immune epitopes were determined by the Stabilized Matrix Method (SMM),SMM-Align Method and Emini Surface Accessibility Prediction.RESULTS: All of the 27 sequences were genotype C,the divergence between the mother and son was 0%-0.8%.Compared with another 50 complete sequences of genotype C,the mother and her son each had 13 specific nucleotides that differed from the other genotype C isolates.AA 1-11 deletion in preS1 was the dominant mutation in the mother (14/18).The 1762T/1764A double mutation existed in all clones of the mother,3 of them were also coupled with G1896A mutation,but none were found in the son.17 bp deletion starting at nucleotide 2330 was the major mutation (5/9) in the son,which caused seven potential HLA class I epitopes and one B cell epitope deletion,and produced a presumptive new start codon,downstream from the original one of the P gene.CONCLUSION: The HBV strain in the son came from his mother,and discrepant mutation occurred in the mother and her son during infection.
Lee, Ching Hua; Zhang, Xiao; Guan, Bochen
2015-12-01
Materials exhibiting negative differential resistance have important applications in technologies involving microwave generation, which range from motion sensing to radio astronomy. Despite their usefulness, there has been few physical mechanisms giving rise to materials with such properties, i.e. GaAs employed in the Gunn diode. In this work, we show that negative differential resistance also generically arise in Dirac ring systems, an example of which has been experimentally observed in the surface states of Topological Insulators. This novel realization of negative differential resistance is based on a completely different physical mechanism from that of the Gunn effect, relying on the characteristic non-monotonicity of the response curve that remains robust in the presence of nonzero temperature, chemical potential, mass gap and impurity scattering. As such, it opens up new possibilities for engineering applications, such as frequency upconversion devices which are highly sought for terahertz signal generation. Our results may be tested with thin films of Bi2Se3 Topological Insulators, and are expected to hold qualitatively even in the absence of a strictly linear Dirac dispersion, as will be the case in more generic samples of Bi2Se3 and other materials with topologically nontrivial Fermi sea regions.
Dynamic characteristics of spur gear transmission system for wind turbine%风电齿轮箱直齿轮传动系统动态特性影响分析
Institute of Scientific and Technical Information of China (English)
赵昕; 陈长征; 刘杰
2015-01-01
综合考虑齿轮啮合刚度、齿侧间隙、齿轮啮合误差以及外部激励等多种非线性因素对齿轮传动系统动态特性的影响，建立风电齿轮箱传动系统高速级直齿轮传动的纯扭转非线性动力学模型，用拉格朗日方程推导了传动系统的振动微分方程。采用 Runge －Kutta 法对直齿轮系统非线性动力学模型进行求解，得到传动系统的时域波形、频谱图和相位图。定量给出齿轮转速、齿侧间隙等参数变化对齿轮传动系统动态特性的影响。结果表明：随着转速和齿侧间隙的增大，传动系统的振动幅值明显增大，系统的振动加剧。为风电齿轮箱传动系统的固有特性，动态响应等动力学特性奠定了一定的基础。%A nonlinear dynamic model of spur gear transmission system is built with consideration of gear mesh stiffness,backlash,error of tooth mesh and external excitation.The vibration differential equations of transmis-sion system are derived by Lagrange equation.Time domain waveform,spectrogram and phase graph of gear transmission system are obtained by Runge-Kutta method.It is studied that parametric variation such as rotating speed and backlashes is influence on dynamic characteristic gear transmission system.The result shows that vibration amplitude of gear transmission system is lager and vibration is more serious with the increase of rotational speed and backlash.The conclusions lay the certain foundation for natural characteristics and dynamic response of spur gear transmission system.
Ermolenko, M. V.; Stankevich, V. V.; Buganov, O. V.; Tikhomirov, S. A.; Ganonenko, S. V.; Kuznetsov, P. I.; Yakushcheva, G. G.
2009-04-01
The nonlinear optical properties of multilayer heterostructures based on zinc chalcogenides are studied. Rapid variations in the reflection and transmission of samples excited by ultrashort laser pulses are demonstrated. The characteristic relaxation times of the induced nonlinearity are 2-5 ps and are almost independent within the experimental error on the excitation energy and temperature of a sample.
Nishimichi, Takahiro; Nakamichi, Masashi; Taruya, Atsushi; Yahata, Kazuhiro; Shirata, Akihito; Saito, Shun; Nomura, Hidenori; Yamamoto, Kazuhiro; Suto, Yasushi
2007-01-01
An acoustic oscillation of the primeval photon-baryon fluid around the decoupling time imprints a characteristic scale in the galaxy distribution today, known as the baryon acoustic oscillation (BAO) scale. Several on-going and/or future galaxy surveys aim at detecting and precisely determining the BAO scale so as to trace the expansion history of the universe. We consider nonlinear and redshift-space distortion effects on the shifts of the BAO scale in $k$-space using perturbation theory. The resulting shifts are indeed sensitive to different choices of the definition of the BAO scale, which needs to be kept in mind in the data analysis. We present a toy model to explain the physical behavior of the shifts. We find that the BAO scale defined as in Percival et al. (2007) indeed shows very small shifts ($\\lesssim$ 1%) relative to the prediction in {\\it linear theory} in real space. The shifts can be predicted accurately for scales where the perturbation theory is reliable.
Xue, Jie; Gui, Dongwei
2015-01-01
The inland river watersheds of arid Northwest China represent an example of how, in recent times, climatic warming has increased the complexity of Earth's hydrological processes. In the present study, the linear and nonlinear characteristics of the runoff response to temperature and precipitation were investigated in the Qira River basin, located on the northern slope of the Kunlun Mountains. The results showed that average temperature on annual and seasonal scales has displayed a significantly increasing trend, but this has not been reflected in accumulated precipitation and runoff. Using path analysis, a positive link between precipitation and runoff was found both annually and in the summer season. Conversely, it was found that the impact of temperature on runoff has been negative since the 1960s, attributable to higher evaporation and infiltration in the Qira River basin. Over the past 50 years, abrupt changes in annual temperature, precipitation and runoff occurred in 1997, 1987 and 1995, respectively. Combined with analysis using the correlation dimension method, it was found that the temperature, precipitation and runoff, both annually and seasonally, possessed chaotic dynamic characteristics, implying that complex hydro-climatic processes must be introduced into other variables within models to describe the dynamics. In addition, as determined via rescaled range analysis, a consistent annual and seasonal decreasing trend in runoff under increasing temperature and precipitation conditions in the future should be taken into account. This work may provide a theoretical perspective that can be applied to the proper use and management of oasis water resources in the lower reaches of river basins like that of the Qira River.
Cakoni, Fioralba; Haddar, Houssem
2013-10-01
In inverse scattering theory, transmission eigenvalues can be seen as the extension of the notion of resonant frequencies for impenetrable objects to the case of penetrable dielectrics. The transmission eigenvalue problem is a relatively late arrival to the spectral theory of partial differential equations. Its first appearance was in 1986 in a paper by Kirsch who was investigating the denseness of far-field patterns for scattering solutions of the Helmholtz equation or, in more modern terminology, the injectivity of the far-field operator [1]. The paper of Kirsch was soon followed by a more systematic study by Colton and Monk in the context of developing the dual space method for solving the inverse scattering problem for acoustic waves in an inhomogeneous medium [2]. In this paper they showed that for a spherically stratified media transmission eigenvalues existed and formed a discrete set. Numerical examples were also given showing that in principle transmission eigenvalues could be determined from the far-field data. This first period of interest in transmission eigenvalues was concluded with papers by Colton et al in 1989 [3] and Rynne and Sleeman in 1991 [4] showing that for an inhomogeneous medium (not necessarily spherically stratified) transmission eigenvalues, if they existed, formed a discrete set. For the next seventeen years transmission eigenvalues were ignored. This was mainly due to the fact that, with the introduction of various sampling methods to determine the shape of an inhomogeneous medium from far-field data, transmission eigenvalues were something to be avoided and hence the fact that transmission eigenvalues formed at most a discrete set was deemed to be sufficient. In addition, questions related to the existence of transmission eigenvalues or the structure of associated eigenvectors were recognized as being particularly difficult due to the nonlinearity of the eigenvalue problem and the special structure of the associated transmission
DEFF Research Database (Denmark)
Guan, Pengyu; Mulvad, Hans Christian Hansen; Tomiyama, Yutaro
2011-01-01
We demonstrate a single-channel 1.28 Tbit/s-525 km transmission using OTDM of subpicosecond DQPSK signals. In order to cope with transmission impairments due to time-varying higherorder PMD, which is one of the major limiting factors in such a longhaul ultrahigh-speed transmission, we newly...
Iyer, Aishwarya R; Zellem, Robert T; Line, Michael R; Roudier, Gael; Rocha, Graca; Livingston, John H
2015-01-01
Currently, 19 transiting exoplanets have published transmission spectra obtained with the Hubble/WFC3 G141 near-IR grism. Using this sample, we have undertaken a uniform analysis incorporating measurement-error debiasing of the spectral modulation due to H$_{2}$O, measured in terms of the estimated atmospheric scale height, ${H_s}$. For those planets with a reported H$_{2}$O detection (10 out of 19), the spectral modulation due to H$_{2}$O ranges from 0.9 to 2.9 ${H_s}$ with a mean value of 1.8 ${H_s}$. This spectral modulation is significantly less than predicted for clear atmospheres. For the group of planets in which H$_{2}$O has been detected, we find the individual spectra can be coherently averaged to produce a characteristic spectrum in which the shape, together with the spectral modulation of the sample, are consistent with a range of H$_{2}$O mixing ratios and cloud-top pressures, with a minimum H$_{2}$O mixing ratio of 23 ppm corresponding to the cloud-free case. Using this lower limit, we show that...
Energy Technology Data Exchange (ETDEWEB)
Verma, Dinkar, E-mail: dinkar@iitk.ac.in [Nuclear Engineering and Technology Program, Indian Institute of Technology Kanpur, Kanpur 208 016 (India); Kalra, Manjeet Singh, E-mail: drmanjeet.singh@dituniversity.edu.in [DIT University, Dehradun 248 009 (India); Wahi, Pankaj, E-mail: wahi@iitk.ac.in [Department of Mechanical Engineering, Indian Institute of Technology Kanpur, Kanpur 208 016 (India)
2017-04-15
Highlights: • A simplified model with nonlinear void reactivity feedback is studied. • Method of multiple scales for nonlinear analysis and oscillation characteristics. • Second order void reactivity dominates in determining system dynamics. • Opposing signs of linear and quadratic void reactivity enhances global safety. - Abstract: In the present work, the effect of nonlinear void reactivity on the dynamics of a simplified lumped-parameter model for a boiling water reactor (BWR) is investigated. A mathematical model of five differential equations comprising of neutronics and thermal-hydraulics encompassing the nonlinearities associated with both the reactivity feedbacks and the heat transfer process has been used. To this end, we have considered parameters relevant to RBMK for which the void reactivity is known to be nonlinear. A nonlinear analysis of the model exploiting the method of multiple time scales (MMTS) predicts the occurrence of the two types of Hopf bifurcation, namely subcritical and supercritical, leading to the evolution of limit cycles for a range of parameters. Numerical simulations have been performed to verify the analytical results obtained by MMTS. The study shows that the nonlinear reactivity has a significant influence on the system dynamics. A parametric study with varying nominal reactor power and operating conditions in coolant channel has also been performed which shows the effect of change in concerned parameter on the boundary between regions of sub- and super-critical Hopf bifurcations in the space constituted by the two coefficients of reactivities viz. the void and the Doppler coefficient of reactivities. In particular, we find that introduction of a negative quadratic term in the void reactivity feedback significantly increases the supercritical region and dominates in determining the system dynamics.
Institute of Scientific and Technical Information of China (English)
田祖织; 侯友夫; 王囡囡
2011-01-01
为了保证磁流变传动装置的动力传递效果,采用实验方法,分析了不同壁面材料、表面粗糙度大小、壁面形貌、滑差转速及工作间隙对磁流变传力性能的影响规律。研究表明壁面材料对磁流变液动力传递效果影响较为明显,材料磁导率越低,传递转矩越小,容易发生壁面滑移现象;壁面形貌亦为影响传力效果的主要因素,凹凸同心圆表面减弱了磁流变液的传力性能;高滑差转速时,磁流变液颗粒成链较为复杂,其传递转矩随滑差转速的增加而逐渐降低,而工作间距对其传力性能影响不大。%To ensure the torque transmission properties of magnetorheological transmission device,the experimental method is used to analyze the effect of material,rough,surface morphology of disk,slip speed and working gap on the torque transmission properties.The results indicate that material of wall has a significant influence on the properties,the lower the permeability of material,the smaller the torque transmits,and the wall effect will appear;the surface morphology of disk has also an important influence on the transmission properties,the concave convex concentric circles surface reduces the torque;when the slip speed is higher,the process of particles chains formed is complex and the torque will be lower,the working distance has little effect on the transmission properties.
In, Visarath; Longhini, Patrick; Kho, Andy; Neff, Joseph D.; Leung, Daniel; Liu, Norman; Meadows, Brian K.; Gordon, Frank; Bulsara, Adi R.; Palacios, Antonio
2012-12-01
The nonlinear channelizer is an integrated circuit made up of large parallel arrays of analog nonlinear oscillators, which, collectively, serve as a broad-spectrum analyzer with the ability to receive complex signals containing multiple frequencies and instantaneously lock-on or respond to a received signal in a few oscillation cycles. The concept is based on the generation of internal oscillations in coupled nonlinear systems that do not normally oscillate in the absence of coupling. In particular, the system consists of unidirectionally coupled bistable nonlinear elements, where the frequency and other dynamical characteristics of the emergent oscillations depend on the system's internal parameters and the received signal. These properties and characteristics are being employed to develop a system capable of locking onto any arbitrary input radio frequency signal. The system is efficient by eliminating the need for high-speed, high-accuracy analog-to-digital converters, and compact by making use of nonlinear coupled systems to act as a channelizer (frequency binning and channeling), a low noise amplifier, and a frequency down-converter in a single step which, in turn, will reduce the size, weight, power, and cost of the entire communication system. This paper covers the theory, numerical simulations, and some engineering details that validate the concept at the frequency band of 1-4 GHz.
Vibration signature analysis of multistage gear transmission
Choy, F. K.; Tu, Y. K.; Savage, M.; Townsend, D. P.
1989-01-01
An analysis is presented for multistage multimesh gear transmission systems. The analysis predicts the overall system dynamics and the transmissibility to the gear box or the enclosed structure. The modal synthesis approach of the analysis treats the uncoupled lateral/torsional model characteristics of each stage or component independently. The vibration signature analysis evaluates the global dynamics coupling in the system. The method synthesizes the interaction of each modal component or stage with the nonlinear gear mesh dynamics and the modal support geometry characteristics. The analysis simulates transient and steady state vibration events to determine the resulting torque variations, speeds, changes, rotor imbalances, and support gear box motion excitations. A vibration signature analysis examines the overall dynamic characteristics of the system, and the individual model component responses. The gear box vibration analysis also examines the spectral characteristics of the support system.
DEFF Research Database (Denmark)
Hu, Hao; Jopson, R. M.; Gnauck, A. H.;
2016-01-01
We demonstrate compensation of fiber nonlinearities using repeated optical phase conjugation (OPC) in a WDM system with eight 32-Gbaud PDM 16-QAM channels, showing improved performance over a single mid-span OPC and no OPC....
Energy Technology Data Exchange (ETDEWEB)
Chevriaux, D
2007-06-15
We study wave scattering in different nonlinear media possessing a natural forbidden band gap. In particular, we show the existence of a bistable behavior in media governed by the sine-Gordon equation (short pendular chain, Josephson junction array, quantum Hall bilayer), or the nonlinear Schroedinger equation (Kerr and Bragg media), in discrete and continuous models. These different media are submitted to periodic boundary conditions with a frequency in the forbidden band gap and an amplitude that determines their stability states. Indeed, for a sufficient amplitude (supra-transmission), the medium switches from reflector to transmitter, hence allowing the output signal to jump from evanescent to large values. We give a complete analytical description of the bistability that allows to understand the different stationary states observed and to predict the switch of one state to the other. (author)
Energy Technology Data Exchange (ETDEWEB)
Han, S.W.; Cho, H.G. [Korea Electrotechnology Research Institute, Changwon (Korea); He, J.L. [Tsinghua University, Beijing (Switzerland)
2000-02-01
The purpose of this study is to discuss the lightning withstand levels (LWLs) of two 110 kV transmission lines before and after line arresters made with polymeric housing are installed on the towers, the lightning discharging currents through arresters and lightning energies absorbed by line arresters. The LWLs can be highly increased by installing line arresters on the transmission line towers in parallel with the insulator strings. It is not problem that the polymeric ZnO surge arresters are used in transmission lines to limit lightning overvoltages. (author). 9 refs., 11 figs., 1 tab.
Directory of Open Access Journals (Sweden)
Hideki Gotoh
2014-10-01
Full Text Available Optical nonlinear effects are examined using a two-color micro-photoluminescence (micro-PL method in a coherently coupled exciton-biexciton system in a single quantum dot (QD. PL and photoluminescence excitation spectroscopy (PLE are employed to measure the absorption spectra of the exciton and biexciton states. PLE for Stokes and anti-Stokes PL enables us to clarify the nonlinear optical absorption properties in the lowest exciton and biexciton states. The nonlinear absorption spectra for excitons exhibit asymmetric shapes with peak and dip structures, and provide a distinct contrast to the symmetric dip structures of conventional nonlinear spectra. Theoretical analyses with a density matrix method indicate that the nonlinear spectra are caused not by a simple coherent interaction between the exciton and biexciton states but by coupling effects among exciton, biexciton and continuum states. These results indicate that Fano quantum interference effects appear in exciton-biexciton systems at QDs and offer important insights into their physics.
Nonlinear Ultrasonic Phased Array Imaging
Potter, J. N.; Croxford, A. J.; Wilcox, P. D.
2014-10-01
This Letter reports a technique for the imaging of acoustic nonlinearity. By contrasting the energy of the diffuse field produced through the focusing of an ultrasonic array by delayed parallel element transmission with that produced by postprocessing of sequential transmission data, acoustic nonlinearity local to the focal point is measured. Spatially isolated wave distortion is inferred without requiring interrogation of the wave at the inspection point, thereby allowing nonlinear imaging through depth.
Nonlinear ultrasonic phased array imaging
Potter, J N; Croxford, A.J.; Wilcox, P. D.
2014-01-01
This Letter reports a technique for the imaging of acoustic nonlinearity. By contrasting the energy of the diffuse field produced through the focusing of an ultrasonic array by delayed parallel element transmission with that produced by postprocessing of sequential transmission data, acoustic nonlinearity local to the focal point is measured. Spatially isolated wave distortion is inferred without requiring interrogation of the wave at the inspection point, thereby allowing nonlinear imaging t...
Nonlinear ultrasonic phased array imaging.
Potter, J N; Croxford, A J; Wilcox, P D
2014-10-03
This Letter reports a technique for the imaging of acoustic nonlinearity. By contrasting the energy of the diffuse field produced through the focusing of an ultrasonic array by delayed parallel element transmission with that produced by postprocessing of sequential transmission data, acoustic nonlinearity local to the focal point is measured. Spatially isolated wave distortion is inferred without requiring interrogation of the wave at the inspection point, thereby allowing nonlinear imaging through depth.
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
In this paper, an experimental research the effect of ablating material on the reflection and the transmission of microwaves in arc-heated plasma flow is presented by using the C band microwave measuring system. The results show that the ablating material with accidented surface and its high temperature have remarkably affected the reflection and the transmission of microwaves. The experiment proves that the system has outstanding precision and reliability.
VanZante, Dale; Envia, Edmane
2008-01-01
A CFD-based simulation of single-stage turbine was done using the TURBO code to assess its viability for determining acoustic transmission through blade rows. Temporal and spectral analysis of the unsteady pressure data from the numerical simulations showed the allowable Tyler-Sofrin modes that are consistent with expectations. This indicated that high-fidelity acoustic transmission calculations are feasible with TURBO.
Directory of Open Access Journals (Sweden)
Thomas Ekelijn
2011-02-01
Full Text Available Abstract Human cases of bacterial gastro-enteritis are often caused by the consumption of eggs contaminated with Salmonella species, mainly Salmonella enterica serovar Enteriditis (Salmonella Enteritidis. To reduce human exposure, in several countries worldwide surveillance programmes are implemented to detect colonized layer flocks. The sampling schemes are based on the within-flock prevalence, and, as this changes over time, knowledge of the within-flock dynamics of Salmonella Enteritidis is required. Transmission of Salmonella Enteritidis has been quantified in pairs of layers, but the question is whether the dynamics in pairs is comparable to transmission in large groups, which are more representative for commercial layer flocks. The aim of this study was to compare results of transmission experiments between pairs and groups of laying hens. Experimental groups of either 2 or 200 hens were housed at similar densities, and 1 or 4 hens were inoculated with Salmonella Enteritidis, respectively. Excretion was monitored by regularly testing of fecal samples for the presence of Salmonella Enteritidis. Using mathematical modeling, the group experiments were simulated with transmission parameter estimates from the pairwise experiments. Transmission of the bacteria did not differ significantly between pairs or groups. This finding suggests that the transmission parameter estimates from small-scale experiments might be extrapolated to the field situation.
Thomas, Ekelijn; Bouma, Annemarie; Klinkenberg, Don
2011-02-23
Human cases of bacterial gastro-enteritis are often caused by the consumption of eggs contaminated with Salmonella species, mainly Salmonella enterica serovar Enteriditis (Salmonella Enteritidis). To reduce human exposure, in several countries worldwide surveillance programmes are implemented to detect colonized layer flocks. The sampling schemes are based on the within-flock prevalence, and, as this changes over time, knowledge of the within-flock dynamics of Salmonella Enteritidis is required. Transmission of Salmonella Enteritidis has been quantified in pairs of layers, but the question is whether the dynamics in pairs is comparable to transmission in large groups, which are more representative for commercial layer flocks. The aim of this study was to compare results of transmission experiments between pairs and groups of laying hens. Experimental groups of either 2 or 200 hens were housed at similar densities, and 1 or 4 hens were inoculated with Salmonella Enteritidis, respectively. Excretion was monitored by regularly testing of fecal samples for the presence of Salmonella Enteritidis. Using mathematical modeling, the group experiments were simulated with transmission parameter estimates from the pairwise experiments. Transmission of the bacteria did not differ significantly between pairs or groups. This finding suggests that the transmission parameter estimates from small-scale experiments might be extrapolated to the field situation.
Institute of Scientific and Technical Information of China (English)
赵年顺; 孙剑
2014-01-01
采用时域有限差分技术分析了非线性光子晶体点缺陷的双稳态特性，选择一定频率失谐的连续波入射并观察透射现象。分析发现，当连续波功率增加到阈值点时透射率达到最大值。采用大功率脉冲辅助连续波的方式发现点缺陷的透射率一直处于高透射状态，直至连续波功率下降到很低时，透射率才迅速下降。双稳态特性由频率失谐δ、缺陷谐振频率ω0及非线性系数 n2等3个参数决定。采用空间电磁场的摄动理论验证所得结果与数值模拟结果一致。%This paper conducts a research on the bistable characteristics of point defect in two dimensional nonlinear photonic crystals with finite-difference time-domain technique. It analyzes the transmission be-havior of input continuous wave with frequency detuning,and the results show that the maximum transmis-sion is detected when the continuous wave reaches the threshold power. What’s more,the defect can be boosted into high transmission state by superposing continuous wave with a high peak-power pulse,and it won’t decrease rapidly until the continuous wave power is brought down to a very low degree. The fre-quency detuning,the resonant frequency,the nonlinear coefficient n2 are needed to characterize a bistable switch. In addition,the dynamic shift of the cavity modes is derived by using the perturbation theory. The conclusion provides some reference for the design of all optical devices based on PC defect.
Institute of Scientific and Technical Information of China (English)
Wang Chun-Ming; Wang Jin-Feng; Wang Chun-Lei; Chen Hong-Cun; Su Wen-Bin; Zang Guo-Zhong; Qi Peng; Zhao Ming-Lei; Ming Bao-Quan
2004-01-01
The effects of barium on electrical and dielectric properties of the SnO2·Co2Oa.Ta2O5 varistor system sintered at 1250℃ for 60min were investigated. It is found that barium significantly improves the nonlinear properties. The breakdown electrical field increases from 378.0 to 2834.5V/mm, relative dielectric constant (at 1kHz) falls from 1206 to 161 and the resistivity (at 1kHz) rises from 60.3 to 1146.5kΩ·cm with an increase of BaCO3 concentration from 0mol%to 1.00mol%. The sample with 1.00mol% barium has the best nonlinear electrical property and the highest nonlinear coefficient (α=29.2). A modified defect barrier model is introduced to illustrate the grain-boundary barrier formation of barium-doped SnO2-based varistors.
Institute of Scientific and Technical Information of China (English)
Xueqiong; Chen; Xiaoyan; Li; Ziyang; Chen; Jixiong; Pu; Guowen; Zhang; Jianqiang; Zhu
2013-01-01
The intensity distributions of a high-power broadband laser beam passing through a nonlinear optical medium with defects and then propagating in free space are investigated based on the general nonlinear Schr¨odinger equation and the split-step Fourier numerical method. The influences of the bandwidth of the laser beam, the thickness of the medium,and the defects on the light intensity distribution are revealed. We find that the nonlinear optical effect can be suppressed and that the uniformity of the beam can be improved for a high-power broadband laser beam with appropriate wide bandwidth. It is also found that, under the same incident light intensity, a thicker medium will lead to a stronger self-focusing intensity, and that the influence of defects in the optical elements on the intensity is stronger for a narrowband beam than for a broadband beam.
液压机械无级变速器传动特性分析%Analysis of Transmission Characteristics of HMCVT
Institute of Scientific and Technical Information of China (English)
高翔; 朱镇; 朱彧
2013-01-01
通过研究单排行星机构和液压元件的不同组合,提出了适合非道路车辆传动系应用的液压机械无级变速传动方案,并分析了(3+1)段位的分矩-汇速液压机械无级变速器的转速比、功率比和转矩比等传动特性.研究表明:该方案能较好地适应非道路车辆液压机械传动的要求.%The appropriate planetary gear differential train and hydrostatic units are chosen to constitute the hydro-mechanical continuously variable transmission to give the transmissive schemes of HMCVT,which suits the transmission of vehicle.The transmission characteristics of rotary speed ratio,power ratio and rotary torque ratio of HMCVT of the non-road separated torque ratio-fixed speed ratio with the range of (3 + 1) are analyzed.The results show that:the scheme can be better adapt to the hydraulic mechanical transmission requirements of off-road vehicle.
微环谐振器传输特性分析%Transmission Characteristics of Microring Resonator
Institute of Scientific and Technical Information of China (English)
李锋; 张静
2012-01-01
主要研究微环谐振器的基本结构参数对传输特性和微环性能的影响.根据耦合模理论,给出了微环谐振器传输函数的表达式；用传输矩阵法对直波导和弯曲波导之间的耦合进行了分析,研究了耦合系数与微环结构参数之间的关系；利用时域有限差分法对微环谐振器进行数值仿真,得到其频谱响应曲线.通过分析可以得到:波导间距的增大使振幅耦合比率减小；微环半径变小,微环的弯曲损耗就会变大,品质因子变大,自由光谱范围就会变大.相对微环半径,波导厚度对微环的性能参数影响较小.在设计时,应按照实际需求来设计间距和微环半径的大小.%The main work of this paper is to research the relationship between the structure parameters and transmission characteristics, performance. The intensity transfer function of microring resonator throughput port and drop port by using the coupled mode theory of waveguides is deduced. The coupling coefficient between the bent waveguide and the straight waveguide is analyzed, using transfer-matrix method. And the relationship between the coupling coefficient and the structure parameters are discussed. Then the frequency spectrum is gotten by using FDTD simulations. The results show that amplitude coupling ration k is reducing while the gaps between microring and bus waveguides is increasing. The bending radiation loss, quality factor ( Q) and the free spectral range (FSR) are increasing, while the radius of microring is reducing. The width of waveguide relatively has a smaller influence on the performance. So the gaps and the radius should be designed according to the needs.
Shi, Ping; Yu, Hongliu
2014-04-01
Calculation of linear parameters, such as time-domain and frequency-domain analysis of heart rate variability (HRV), is a conventional method for assessment of autonomic nervous system activity. Nonlinear phenomena are certainly involved in the genesis of HRV. In a seemingly random signal the Poincaré plot can easily demonstrate whether there is an underlying determinism in the signal. Linear and nonlinear analysis methods were applied in the computer words inputting experiments in this study for physiological measurement. This study therefore demonstrated that Poincaré plot was a simple but powerful graphical tool to describe the dynamics of a system.
Institute of Scientific and Technical Information of China (English)
林超; 宿新红; 秦大同
2011-01-01
在研究盾构机及行星齿轮机构的基础之上,针对盾构机刀盘驱动系统,提出一种新型盾构机双驱动大功率行星齿轮传动系统,分析了传动系统的原理及其结构;建立了新型传动系统的运动学模型,对该系统的传动特性进行了分析,获得了系统的传动比、系统内部的转速、扭矩的关系和变化规律;通过对比简化实验得到的结果与理论计算得到的结果,其变化规律基本一致,验证了数学模型及分析方法的正确性.双驱动大功率行星齿轮传动系统具有传动比大、承载能力强的特点,能实现低转速、大扭矩输出的功能,满足盾构机的基本工作要求,不仅可取代传统的多个电机同时驱动多个减速器的传动系统,还能实现3种不同型式的盾构机传动系统功能.%On the basis of studying shield machine and planetary transmission, to address cutting drive system of shield machine, a novel dual drive planetary transmission system with large capacity is presented, and its principle and structure are analyzed. Through establishing a new kinematical model of the transmission system and analyzing its characteristics, the transmission ratio, rev and torque relationship and changing rules within the system are acquired. By comparing the simplified experimental results with theoretical results,it is shown that the variation is basically the same, which verifies the correctness of the model and analysis method. The high-power dual-driven planetary geartransmission system with great transmission ratio, strong carrying capacity, can perform the function of low-speed and high-torque output, and meet basic requirements of shield machine. It can not only replace the traditional multi-driven transmission system, but also achieve the transmission function in three different types of shield machine.
Gonzales, J L; Elbers, A R W; Bouma, A; Koch, G; de Wit, J J; Stegeman, J A
2012-03-23
Low pathogenic avian influenza virus (LPAIv) infections of H5 and H7 subtypes in poultry are notifiable to the OIE, hence surveillance programmes are implemented. The rate at which LPAIv strains spread within a flock determines the prevalence of infected birds and the time it takes to reach that prevalence and, consequently, optimal sample size and sampling frequency. The aim of this study was to investigate the transmission characteristics of an H7N7 and an H5N7 LPAIv in layer chickens. Two transmission experiments were performed, which consisted of 30 (first experiment) and 20 (second experiment) pairs of conventional layers, respectively. At the start of the experiments, one chicken per pair was inoculated with LPAIv and the other chicken was contact-exposed. Occurrence of infection was monitored by regularly collecting tracheal and cloacal swab samples, which were examined for the presence of virus RNA by RT-PCR. The results of the test were used to estimate the transmission rate parameter (β), the infectious period (T) and the basic reproduction ratio (R(0)). In addition, egg production and virus shedding patterns were quantified. For the H7N7 virus, the β, T and R(0) estimates were 0.10 (95% confidence interval (CI): 0.04-0.18) day(-1), 7.1 (95% CI: 6.5-7.8) days and 0.7 (95% CI: 0.0-1.7), respectively. With the H5N7 virus, only a few inoculated chickens (5 out of 20) became infected and no transmission was observed. This study shows that transmission characteristics of LPAIv strains may vary considerably, which has to be taken into account when designing surveillance programmes.
Directory of Open Access Journals (Sweden)
Jairam R Lingappa
Full Text Available BACKGROUND: The Partners HSV-2/HIV-1 Transmission Study (Partners Study is a phase III, placebo-controlled trial of daily acyclovir for genital herpes (HSV-2 suppression among HIV-1/HSV-2 co-infected persons to reduce HIV-1 transmission to their HIV-1 susceptible partners, which requires recruitment of HIV-1 serodiscordant heterosexual couples. We describe the baseline characteristics of this cohort. METHODS: HIV-1 serodiscordant heterosexual couples, in which the HIV-1 infected partner was HSV-2 seropositive, had a CD4 count >or=250 cells/mcL and was not on antiretroviral therapy, were enrolled at 14 sites in East and Southern Africa. Demographic, behavioral, clinical and laboratory characteristics were assessed. RESULTS: Of the 3408 HIV-1 serodiscordant couples enrolled, 67% of the HIV-1 infected partners were women. Couples had cohabitated for a median of 5 years (range 2-9 with 28% reporting unprotected sex in the month prior to enrollment. Among HIV-1 susceptible participants, 86% of women and 59% of men were HSV-2 seropositive. Other laboratory-diagnosed sexually transmitted infections were uncommon (500 relative to <350, respectively, p<0.001. CONCLUSIONS: The Partners Study successfully enrolled a cohort of 3408 heterosexual HIV-1 serodiscordant couples in Africa at high risk for HIV-1 transmission. Follow-up of this cohort will evaluate the efficacy of acyclovir for HSV-2 suppression in preventing HIV-1 transmission and provide insights into biological and behavioral factors determining heterosexual HIV-1 transmission. TRIAL REGISTRATION: ClinicalTrials.gov NCT00194519.
Directory of Open Access Journals (Sweden)
Md. Jalil Piran
2015-01-01
Full Text Available This paper proposes a method for channel allocation based on video content requirements and the quality of the available channels in cognitive radio networks (CRNs. Our objective is to save network bandwidth and achieve high-quality video delivery. In this method, the content is divided into clusters based on scene complexity and PSNR. To allocate channel to the clusters over multichannel CRNs, we first need to identify the licensee’s activity and then maximize the opportunistic usage accordingly. Therefore, we classify short and long time transmission opportunities based on the licensee’s activities using a Bayesian nonparametric inference model. Furthermore, to prevent transmission interruption, we consider the underlay mode for transmission of the clusters with a lower bitrate. Next, we map the available spectrum opportunities to the content clusters according to both the quality of the channels and the requirements of the clusters. Then, a distortion optimization model is constructed according to the network transmission mechanism. Finally, to maximize the average quality of the delivered video, an optimization problem is defined to determine the best bitrate for each cluster by maximizing the sum of the logarithms of the frame rates. Our extensive simulation results prove the superior performance of the proposed method in terms of spectrum efficiency and the quality of delivered video.
Energy Technology Data Exchange (ETDEWEB)
Sasaki, S., E-mail: s.sasaki@ecei.tohoku.ac.j [Electrical Engineering Department, Graduate School, Tohoku University, 6-6-05 Aoba Aramaki, Aoba-ku, Sendai, Miyagi 980-8579 (Japan); Shimada, K.; Yagai, T.; Tsuda, M.; Hamajima, T. [Electrical Engineering Department, Graduate School, Tohoku University, 6-6-05 Aoba Aramaki, Aoba-ku, Sendai, Miyagi 980-8579 (Japan); Kawai, N.; Yasui, K. [Okumura Corporation, 5-6-1 Shiba, Minato-ku, Tokyo 180-8381 (Japan)
2010-11-01
We have devised a magnetic levitation type superconducting seismic isolation device taking advantage of the specific characteristic of HTS bulk that the HTS bulk returns to its original position by restoring force against a horizontal displacement. The superconducting seismic isolation device is composed of HTS bulks and permanent magnets (PM rails). The PMs are fixed on an iron plate to realize the same polarities in the longitudinal direction and the different polarities in the transverse direction. The superconducting seismic isolation device can theoretically remove any horizontal vibrations completely. Therefore, the vibration transmissibility in the longitudinal direction of the PM rail becomes zero in theory. The zero vibration transmissibility and the stationary levitation, however, cannot be achieved in the real device because a uniform magnetic field distribution in the longitudinal direction of PM rail cannot be realized due to the individual difference of the PMs. Therefore, to achieve stationary levitation in the real device we adopted a PM-PM system that the different polarities are faced each other. The stationary levitation could be achieved by the magnetic interaction between the PMs in the PM-PM system, while the vibration transmitted to the seismic isolation object due to the magnetic interaction. We adopted a copper plate between the PMs to reduce the vibration transmissibility. The PM-PM system with the copper plate is very useful for realizing the stationary levitation and reducing the vibration transmissibility.
Dynamic Characteristics of Transmission System for the Internal Grinder%内圆磨床传动系统的动力特性分析
Institute of Scientific and Technical Information of China (English)
伍建国; 孙庆鸿; 毛海军; 郁文凯; 蔡英
2002-01-01
基于Riccati传递矩阵法建立了内圆磨床传动系统的动力学模型.由模态柔度和弹性分布率的计算,分析了原内圆磨床传动系统的动态特性,应用动柔度与模态柔度的关系,找出传动系统的危险模态及其该模态上的薄弱环节,提出了结构修改方案,避免了参数调整的盲目性,并预测了其动态性能,在内圆磨床传动系统设计中得到了有效的应用.%The dynamics model of the transmission system of the internal grinder is established on the bases of Riccati transfer matrix. The dynamic characteristics of the internal grinder are obtained by analyzing the relationship between dynamic modal flexibility and modal flexibility, which is used to find out the dangerous model of the transmission system and its weak areas. Then design parameters of weak areas are modified, the new one from the old structure is put forward, and the dynamic characteristics of new structure are forecast through the calculations of the modal flexibility and elasticity distribution rate. This method is applied successfully in designing the transmission system of the internal grinder.
NONLINEAR VIBRATION CHARACTERISTICS OF SHROUDED BLADE FOR CYLINDRICAL PANEL%壳板凸肩叶片的非线性振动特性
Institute of Scientific and Technical Information of China (English)
李红影; 谢里阳; 郭星辉
2013-01-01
A shrouded blade is investigated in this paper. Using Donnell's nonlinear shallow-shell theory, the nonlinear equation of vibration is obtained, in which the geometric nonlinearity, damping, shroud contact normal load and friction between shrouds are taken into account. Discretized by a Galerkin method, the nonlinear mode equations are studied by using numerical and analytical methods, then nonlinear frequency-response curves are obtained. The stability of periodic solutions of the system is also analyzed. The results show that the periodic changes in the direction of the friction force between shrouds cause the discontinuity of vibration characteristics of the system. In order to describe the inherent vibration characteristic of the system, two frequency-response curves are drawn, which respectively adopts the positive and negative directions of the friction force. With the changes of the direction of a friction force in a period of 774, the vibration of the system also jumps between these two curves with a period 774, this effectively suppress the response amplitude of a shrouded blade, and improves its safety.%以凸肩叶片为研究对象,应用Donnell's简化壳理论建立模型的非线性振动方程,考虑了几何非线性、阻尼、凸肩接触面正压力、摩擦力等因素.采用Galerkin法将振动微分方程离散到模态坐标上,分别应用数值法和近似解析法对方程组求解,得到系统的频率响应曲线,并讨论了系统周期解的稳定性.结果表明,由于凸肩接触面之间摩擦力方向周期性改变,导致系统的振动特性产生不连续性,以摩擦力为正、负方向分别绘制一条频率响应曲线.则随着摩擦力方向T/4周期变换一次,系统的振动也以T/4为周期在两条频率响应曲线上来回跳跃,从而有效抑制叶片的振动响应,提高叶片使用的安全性.
Institute of Scientific and Technical Information of China (English)
吴青聪; 王兴松; 杜峰坡; 陈林
2015-01-01
Tendon-sheath actuation system in pull-pull configuration is widely used in surgical and search/rescue robots, because it can provide a kind of simple yet dexterous remote transmission. The undesirable nonlinear characteristics arising from the friction between contact surfaces and the tendon compliance are the major obstacles for robot control. Considering the limitation that the existing tendon-sheath transmission model is only applicable to elastic load, the torque transmission model under any load conditions is proposed. An experimental setup is established to verify the torque transmission characteristics and discuss the influence factors of torque transfer efficiency. The looseness phenomenon of the system is analyzed in order to calculate the required minimum preload. A friction torque compensation controller without distal-end feedback is designed to ensure that the output of the system can effectively track the expected torque trajectory, and the effectiveness of the scheme is validated by experiments. Thus, studies on the torque transmission characteristics have provided theoretical bases for the torque control of the tendon-sheath actuated robots.%双套索驱动系统因其简单、灵巧以及远距传动的特点被广泛应用于手术机器人以及搜救机器人设计中。由于套索接触面间的摩擦力以及绳索的柔性所产生的非线性特性是这类机器人控制的主要难题。针对现有双套索传动模型只适用于弹性负载，具有明显的局限性的问题，推导任意负载条件下的双套索力矩传动模型。建立双套索传动特性试验平台，通过试验对力矩传动模型进行验证，并讨论双套索力矩传动效率的影响因素。分析系统松弛现象并计算避免松弛所需的最小预紧力。基于力矩传动模型设计一种无末端反馈的摩擦补偿控制器，使系统的输出能跟随期望的力矩轨迹，并通过试验验证该方案的有效性。针对力矩
Institute of Scientific and Technical Information of China (English)
王福谦
2011-01-01
利用复数坐标系z上的儒可夫斯基变换，给出椭圆柱传输线内的TEM波的电磁场分布规律，利用数学软件Matlab绘制出TEM波在椭圆柱传输线横向截面上的场结构图，并计算出其特性阻抗。%By using Roucofeskie＇s conversion in complex coordinate system the distribution law of the electromagnetic field of the TEM wave in an elliptic cylinder transmission line is given, and by using Matlab software the map of the electromagnetic field structure of TEM wave in the cross-section of the elliptic cylinder transmission line is plotted, and its characteristic impedance is calculated.
Institute of Scientific and Technical Information of China (English)
Zijia Zhang(张自嘉); Wenkang Shi(施文康)
2003-01-01
The characteristics of the transmission spectrum of the Long-period fiber gratings (LPFGs) based on thecoupling of core mode to a higher order cladding mode (HE mode) are investigated using the coupled modetheory. This kind of LPFGs is different from that based on the coupling of core mode to a lower ordercladding mode because of the effect of the coupling of core mode to EH cladding mode. When the claddingmode order is higher, the coupling coefficients of core mode to HE and EH cladding modes are comparableand both of the propagation constants of HE and EH cladding modes approach, so the spectrum has anadditional loss peak. The bandwidth of LPFG based on the coupling of core mode to different claddingmode differs greatly. With the change of the mode orders from lower to higher, the transmission spectrumchanges from narrow to wide and more narrow.
DEFF Research Database (Denmark)
Guan, Pengyu; Mulvad, Hans Christian Hansen; Tomiyama, Yutaro
2011-01-01
developed an ultrafast timedomain optical Fourier transformation technique in a round-trip configuration. By applying this technique to subpicosecond pulses, transmission impairments were greatly reduced, and BER performance below FEC limit was obtained with increased system margin. Copyright © 2011...
2012-01-01
Until recently, transmissible spongiform encephalopathy (TSE) disease in cattle was thought to be caused by a single agent strain, bovine spongiform encephalopathy (BSE) (classical BSE or BSE-C). However, due to the initiation of a large-scale surveillance programme throughout Europe, two atypical BSE strains, bovine amyloidotic spongiform encephalopathy (BASE, also named BSE-L) and BSE-H have since been discovered. These atypical BSE isolates have been previously transmitted to a range of tr...
Energy Technology Data Exchange (ETDEWEB)
Serkez, Svitozar; Kocharyan, Vitali; Saldin, Evgeni; Zagorodnov, Igor [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Geloni, Gianluca [European XFEL GmbH, Hamburg (Germany)
2013-09-15
We demonstrate that the output radiation characteristics of the European XFEL sources at nominal operation point can be easily made significantly better than what is currently reported in the TDRs of scientific instruments and X-ray optics. In fact, the output SASE characteristics of the baseline European XFEL have been previously optimized assuming uniform undulators at a nominal operating point of 5 kA peak current, without considering the potential of undulator tapering in the SASE regime. In order to illustrate this point, we analyze the case of an electron bunch with nominal parameters. Based on start-to-end simulations, we demonstrate that nonlinear undulator tapering allows one to achieve up to a tenfold increase in peak power and photon spectral density in the conventional SASE regime, without modification to the baseline design. The FEL code Genesis has been extensively used for these studies. In order to increase our confidence in simulation results, we cross-checked outcomes by reproducing simulations in the deep nonlinear SASE regime with tapered undulator using the code ALICE.
DEFF Research Database (Denmark)
Sackey, I.; Da Ros, Francesco; Jazayerifar, M.;
2014-01-01
inversion of 5 × 28-GBd polarization-multiplexed 16- QAM signals. Signal quality factor (Q-factor) improvements of 1.1 dB and 0.8 dB were obtained in the cases of a single-channel and a five-channel wavelength-division multiplexing (WDM) system, respectively. The experimental results are compared......We present experimental and numerical investigations of Kerr nonlinearity compensation in a 400-km standard single-mode fiber link with distributed Raman amplification with backward pumping. A dual-pump polarization-independent fiber-based optical parametric amplifier is used for mid-link spectral...
DEFF Research Database (Denmark)
Sackey, Isaac; Da Ros, Francesco; Karl Fischer, Johannes;
2015-01-01
We experimentally investigate Kerr nonlinearity mitigation of a 28-GBd polarization-multiplexed 16-QAM signal in a five-channel 50-GHz spaced wavelength-division multiplexing (WDM) system. Optical phase conjugation (OPC) employing the mid-link spectral inversion technique is implemented by using...... a dual-pump polarization-independent fiber-optic parametric amplifier and compared to digital backpropagation (DBP) compensation over up to 800-km in a dispersion-managed link. In the single-channel case, the use of the DBP algorithm outperformed the OPC with a Q-factor improvement of 0.9 dB after 800-km...
DEFF Research Database (Denmark)
Sackey, Isaac; Da Ros, Francesco; Karl Fischer, Johannes
2015-01-01
a dual-pump polarization-independent fiber-optic parametric amplifier and compared to digital backpropagation (DBP) compensation over up to 800-km in a dispersion-managed link. In the single-channel case, the use of the DBP algorithm outperformed the OPC with a Q-factor improvement of 0.9 dB after 800-km......We experimentally investigate Kerr nonlinearity mitigation of a 28-GBd polarization-multiplexed 16-QAM signal in a five-channel 50-GHz spaced wavelength-division multiplexing (WDM) system. Optical phase conjugation (OPC) employing the mid-link spectral inversion technique is implemented by using...
Institute of Scientific and Technical Information of China (English)
陈会涛; 秦大同; 吴晓铃; 周志刚; 杨军
2012-01-01
为研究综合传递误差的随机波动对风力发电机齿轮传动系统动力学特性的影响,考虑齿轮时变啮合刚度、综合传递误差等因素,建立风力发电机行星齿轮传动系统纯扭转动力学模型.以随机风速引起的齿轮系统转矩波动作为行星齿轮系统的外部激励,对某1.5 MW风力发电机行星齿轮传动系统的动力学特性进行仿真分析,得到系统各响应量时域内的统计特征和齿轮副间的动态啮合力统计特征.分析表明:行星架、行星轮和太阳轮在扭转方向上的振动特性与外部载荷相关,其振动位移与外部载荷波动有相似变化的趋势；综合传递误差随机分量的离散程度对行星齿轮系统的动态特性和齿轮副间的动态啮合力有较大影响.随着综合传递误差随机分量离散程度的增加,行星架、太阳轮和行星轮在扭转方向上的振动幅值明显增加；综合传递误差随机分量的随机性使齿轮副间动态啮合力产生随机波动,随机分量离散程度越大,动态啮合力波动越明显；当随机分量的离散程度达到某一值时,齿轮啮合过程发生脱离,引发啮合冲击.%A purely rotational nonlinear dynamic model of planetary gear transmission system including time-varying mesh stiffness and synthetic mesh errors is developed to research the dynamic behavior of the wind turbine with the random fluctuation of synthetic mesh errors. Numerical method is used to simulate the planetary gear system of 1.5 MW wind turbine with the consideration of the torque fluctuation of gear transmission system caused by wind speed and transmission error random variable caused by manufacture and assembly. The statistical characteristics of responses of the planetary gear system and dynamic mesh force of gear pairs are obtained. The statistic analysis show that: the vibration features of the planetary carrier, the sun gear and the planetary gear are closely related to the external
Study on the optical transmission characteristics of Cassegrain antenna%卡塞格伦天线光传输特性研究
Institute of Scientific and Technical Information of China (English)
孙全国
2015-01-01
In this paper,the transmission theory of Casey Glenn optical antenna system are analyzed,the transmission properties of Casey Glenn optical antenna on the basis of the simulation analysis,through the experiment discovered that the transmission efficiency and lotus root axis deviation will directly affect the Casey Glenn antenna efficiency,we expect this research can provide feasible ideas and methods for research of Casey Glenn optics antenna characteristics problems.%本文对卡塞格伦光学天线系统的传输理论进行了分析，在此基础上对卡塞格伦光学天线的传输特性进行了仿真实验分析，通过实验发现偏轴将直接影响卡塞格伦天线的传输效率和藕合效率，期望本文的研究能够为卡塞格伦光学天线特性问题的研究提供可行的思路和方法。
Wilson, Rona; Hart, Patricia; Piccardo, Pedro; Hunter, Nora; Casalone, Cristina; Baron, Thierry; Barron, Rona M
2012-05-01
Until recently, transmissible spongiform encephalopathy (TSE) disease in cattle was thought to be caused by a single agent strain, bovine spongiform encephalopathy (BSE) (classical BSE or BSE-C). However, due to the initiation of a large-scale surveillance programme throughout Europe, two atypical BSE strains, bovine amyloidotic spongiform encephalopathy (BASE, also named BSE-L) and BSE-H have since been discovered. These atypical BSE isolates have been previously transmitted to a range of transgenic mouse models overexpressing PrP from different species at different levels, on a variety of genetic backgrounds. To control for genetic background and expression level in the analysis of these isolates, we performed here a comprehensive comparison of the neuropathological and molecular properties of all three BSE agents (BASE, BSE-C and BSE-H) upon transmission into the same gene-targeted transgenic mouse line expressing the bovine prion protein (Bov6) and a wild-type control of the same genetic background. Significantly, upon challenge with these BSE agents, we found that BASE did not produce shorter survival times in these mice compared with BSE-C, contrary to previous studies using overexpressing bovine transgenic mice. Amyloid plaques were only present in mice challenged with atypical BSE and neuropathological features, including intensity of PrP deposition in the brain and severity of vacuolar degeneration were less pronounced in BASE compared with BSE-C-challenged mice.
Nonlinear graphene metamaterial
Nikolaenko, Andrey E; Atmatzakis, Evangelos; Luo, Zhiqiang; Shen, Ze Xiang; De Angelis, Francesco; Boden, Stuart A; Di Fabrizio, Enzo; Zheludev, Nikolay I
2012-01-01
We demonstrate that the broadband nonlinear optical response of graphene can be resonantly enhanced by more than an order of magnitude through hybridization with a plasmonic metamaterial,while retaining an ultrafast nonlinear response time of ~1 ps. Transmission modulation close to ~1% is seen at a pump uence of ~0.03 mJ/cm^2 at the wavelength of ~1600 nm. This approach allows to engineer and enhance graphene's nonlinearity within a broad wavelength range enabling applications in optical switching, mode-locking and pulse shaping.
Institute of Scientific and Technical Information of China (English)
Shinobu; Tamaoki; Tetsufumi; Tsuzaki; Motoki; Kakui; Masayuki; Shigematsu
2003-01-01
We have investigated the transient characteristics of discrete Raman Amplifiers and found that the response time caused by gain saturation is dependent upon the wavelength, which corresponds to the effective length of the pump light.
Yun, Seungman; Kim, Ho Kyung; Han, Jong Chul; Kam, Soohwa; Youn, Hanbean; Cunningham, Ian A.
2017-03-01
The imaging properties of a complementary metal-oxide-semiconductor (CMOS) active-pixel photodiode array coupled to a thin gadolinium-based granular phosphor screen with a fiber-optic faceplate are investigated. It is shown that this system has a nonlinear response at low detector exposure levels (<10 mR), resulting in an over-estimation of the detective quantum efficiency (DQE) by a factor of two in some cases. Errors in performance metrics on this scale make it difficult to compare new technologies with established systems and predict performance benchmarks that can be achieved in practice and help understand performance bottlenecks. It is shown the CMOS response is described by a power-law model that can be used to linearize image data. Linearization removed an unexpected dependence of the DQE on detector exposure level.
Institute of Scientific and Technical Information of China (English)
郭利京; 韩刚; 胡联; 孔小红
2014-01-01
Pork prices can not effectively reflect the information of supply and demand for asymmetric price transmission ,which distorts the resource allocation of the pig industry market and is the main reason of cyclical fluctuations in pork prices .This paper discusses the causes of asymmetry price transmission ,economic entities’asymmetric information and the characteristics of vertical pork markets .The mechanism of asymmetric price transmission is generated the intrinsic existence of information asymmetry .Therefore,expanding the scale of pig farming and reducing associated links are the key to breaking the longitudinally asymmetric information , asymmetry price transmission and promoting the healthy development of the pig industry .%价格传递非对称性使猪肉价格不能有效反映市场供求，扭曲了养猪业市场资源配置，是引起我国猪肉价格周期性大幅度波动的主要原因。以纵向市场结构理论和价格形成机制为基础，对比分析了纵向分离市场结构和一体化市场结构下的猪肉价格、猪肉销售量和纵向产业链整体利润情况。结果表明，信息不对称导致的逆向压价效应，不但扭曲了生猪市场价格、降低生猪养殖者利润，也误导了生猪养殖行为；数量众多的生猪散养户、可维持信息不对称和过多纵向关联环节是导致猪肉价格传递非对称的内在原因。因此，扩大生猪养殖规模和减少纵向关联环节数量是打破信息不对称、价格传递非对称性和促进养猪业健康发展的根本措施。
Molia, Sophie; Traoré, Idrissa; Kamissoko, Badian; Diakité, Adama; Sidibé, Maimouna Sanogo; Sissoko, Kadiatou Diarra; Pfeiffer, Dirk Udo
2015-10-01
We aimed at characterizing commercial and traditional village poultry farming in Mali, with a focus on practices influencing the risk of transmission of avian influenza and Newcastle disease. Surveys were conducted in 2009-2011 in a study area covering approximately 98% of the Malian poultry population. Among the 282 commercial farms investigated, of which 64 had not been known by the government authorities, 83% were located within a 50km radius from the capitals of the country and regions and 54% had low biosecurity standard. Among the 152 randomly selected village household flocks investigated, characteristics were overall similar to those in other African countries but some differences were notable including a large flock size (median 44 poultry), a low presence of ducks and geese (11% and 1.1% of flocks, respectively), vaccination against Newcastle disease being common (49% of flocks), a low proportion of households selling sick and dead birds (0.7% and 0%, respectively) and limited cohabitation between poultry and humans at night. Our recommendations to limit the risk of disease transmission include (1) for commercial farms, to introduce compulsory farm registration and accreditation, to increase technical proficiency and access to credit for farms with low biosecurity, and to support poultry producer associations; (2) for village poultry, to promote better quarantine and management of sick and dead birds. Such detailed knowledge of country-specific characteristics of poultry production systems is essential to be able to develop more efficient disease risk management policies.
Iñiguez-de-la-Torre, I.; González, T.; Pardo, D.; Gardès, C.; Roelens, Y.; Bollaert, S.; Mateos, J.
2009-05-01
In this work, the influence of the geometry of the different branches on the output characteristics of InAlAs/InGaAs three-branch junctions is analyzed. At room temperature experimental measurements show that when increasing the width of the horizontal branches, the nonlinear behavior persists, even if less pronounced. This implies a reduction in the (typically high) impedance of these nanodevices, which is quite interesting in order to minimize the influence of parasitic capacitances on their cutoff frequency and to decrease the reflected power due to the mismatch with the 50 Ω standard equipment. The width of the vertical branch is also a relevant parameter, nonlinear effects being more important for narrow branches. In both cases surface charges at the etched boundaries of the branches play a key role. Monte Carlo simulations (performed with a self-consistent surface charge model recently proposed by the authors) are used to explain the physical origin of the observed behavior and to improve the device performance. We focus on the enhancement of their efficiency as a way to develop their promising functionalities in various analog and digital circuits.
Acoustic Nonlinear Behaviour of Microbubble Contrast Agent
Institute of Scientific and Technical Information of China (English)
俞金飞; 陆荣荣; 龚秀芬; 石涛
2002-01-01
We have investigated the nonlinear characteristics of a microbubble contrast agent Sonazoid R (Nycomed,Norway), including the second, third, 1/2-order, 3/2-order and 5/2-order harmonics. We have measured the 1/2-order subharmonic response to different transmission sound pressures. We have found that subharmonic signals cannot be generated until the acoustic pressure reaches a certain value, which is the most different subharmonic from high harmonics. This result is favourable for the further study of the subharmonic in the bubbly liquid.The 3/2-order ultraharmonic response to acoustic pressure was also measured.
Energy Technology Data Exchange (ETDEWEB)
Thoelking, Johannes; Sekar, Yuvaraj; Fleckenstein, Jens; Lohr, Frank; Wenz, Frederik; Wertz, Hansjoerg [Heidelberg Univ., University Medical Center Mannheim (Germany). Dept. of Radiation Oncology
2016-11-01
Online verification and 3D dose reconstruction on daily patient anatomy have the potential to improve treatment delivery, accuracy and safety. One possible implementation is to recalculate dose based on online fluence measurements with a transmission detector (TD) attached to the linac. This study provides a detailed analysis of the influence of a new TD on treatment beam characteristics. The influence of the new TD on surface dose was evaluated by measurements with an Advanced Markus Chamber (Adv-MC) in the build-up region. Based on Monte Carlo simulations, correction factors were determined to scale down the over-response of the Adv-MC close to the surface. To analyze the effects beyond d{sub max} percentage depth dose (PDD), lateral profiles and transmission measurements were performed. All measurements were carried out for various field sizes and different SSDs. Additionally, 5 IMRT-plans (head and neck, prostate, thorax) and 2 manually created test cases (3 x 3 cm{sup 2} fields with different dose levels, sweeping gap) were measured to investigate the influence of the TD on clinical treatment plans. To investigate the performance of the TD, dose linearity as well as dose rate dependency measurements were performed. With the TD inside the beam an increase in surface dose was observed depending on SSD and field size (maximum of +11%, SSD = 80 cm, field size = 30 x 30 cm{sup 2}). Beyond d{sub max} the influence of the TD on PDDs was below 1%. The measurements showed that the transmission factor depends slightly on the field size (0.893-0.921 for 5 x 5 cm{sup 2} to 30 x 30 cm{sup 2}). However, the evaluation of clinical IMRT-plans measured with and without the TD showed good agreement after using a single transmission factor (γ{sub (2%/2mm)} > 97%, δ{sub ±3%} >95%). Furthermore, the response of TD was found to be linear and dose rate independent (maximum difference <0.5% compared to reference measurements). When placed in the path of the beam, the TD introduced
Institute of Scientific and Technical Information of China (English)
朱雷; 金宁德; 高忠科; 杜萌; 王振亚
2012-01-01
Based on the conductance fluctuation signals measured from vertical upward oil-gas-water three-phase flow experiment, time frequency representation and surrogate data method were used to investigate dynamical characteristics of oil-in-water type bubble and slug flows. The results indicate that oil-in-water type bubble flow will turn to deterministic motion with the increase of oil phase fraction f o and superficial gas velocity U sg under fixed flowrate of oil-water mixture Q mix . The dynamics of oil-in-water type slug flow becomes more complex with the increase of U sg under fixed flowrate of oil-water mixture. The change of f o leads to irregular influence on the dynamics of slug flow. These interesting findings suggest that the surrogate data method can be a faithful tool for characterizing dynamic characteristics of oil-in-water type bubble and slug flows.
Digital signal processing for fiber nonlinearities [Invited
DEFF Research Database (Denmark)
Cartledge, John C.; Guiomar, Fernando P.; Kschischang, Frank R.
2017-01-01
This paper reviews digital signal processing techniques that compensate, mitigate, and exploit fiber nonlinearities in coherent optical fiber transmission systems......This paper reviews digital signal processing techniques that compensate, mitigate, and exploit fiber nonlinearities in coherent optical fiber transmission systems...
Mekap, Anita; Das, Piyush R.; Choudhary, R. N. P.
2016-08-01
The non-linear behavior of polycrystalline-ZnO-based voltage-dependent resistors is considered in the present study. A high-temperature solid-state reaction route was used to synthesize polycrystalline samples of ZnO modified by small amounts of the trioxides Sb2O3, Bi2O3, Fe2O3, etc. in various proportions. X-ray diffraction and scanning electron microscopy techniques were used to study the structural and microstructural characteristics of modified ZnO. Detailed studies of non-linear phenomena of the I-V characteristics, dielectric permittivity ( ɛ r), impedance ( Z), etc. of the samples have provided many interesting results. All the samples exhibited dielectric anomaly. Non-linear variation in polarization with electric field for all the samples was observed. Moreover, significant non-linearity in the I-V characteristics was observed in the breakdown region of all the samples at room temperature. The non-linear coefficient ( α) in different cases, i.e. for I- V, ɛ r- f, ɛ r- T, and ɛ r- Z, was calculated and found to be appreciable. The frequency dependence of ac conductivity suggests that the material obeys Jonscher's universal power law.
Directory of Open Access Journals (Sweden)
M Sharifjaafari
2016-07-01
Full Text Available Introduction: Researches show that medical professionalism is threatened and it is needed a proper educational intervention. Hidden curriculum plays a very important role of transmission of professional values. Most of expert curriculum planners found that the effects of the hidden curriculum of education from the educational dimensions, in particular, in transmission of values and norms is far more powerful than the obvious curriculum. Methods: In this qualitative content analysis, 15 students individually and 9 students in one group were selected in Bushehr University of Medical Sciences and semistructures interview was done. Participants of this study were medical students, nursing and midwifery students, operating room and anesthesia students in Bushehr University of Medical Sciences. Data were analyzed by using content analysis in seven steps. The accuracy of data was confirmed from various methods. Conclusion: After coding and categorizing the obtained data, the students mentioned to the three main themes as the hidden curriculum role in transition of professional characteristic. These three main roles were "communication", "principles, laws and regulations" and "supportive atmosphere". Results: Inappropriate organizational structure in the health system created some serious obstacles in the paths of professionalism. Based on the findings, some factors were considered as facilitating professionalism. They included having a good relationship, having encouragement and support system, and having the rules facilitate professionalism and organizations as well as organizational and managerial failures of Ministry of Health, educational system and lack of attention to the hidden curriculum in the transfer of professionalism were considered as inhibitors.
Directory of Open Access Journals (Sweden)
A. Mallaiah
2017-02-01
Full Text Available The electronic transport properties of electrons in a molecules are observed by using Non equilibrium Green’s function(NEGF. We present a extremely through and careful computational approach well ordered method to do a framework analysis of donor (CH3 and acceptor (CN molecules connected between the Au(111 contacts, and also observed current progress through molecular devices depends on number of bonds or not. Such observations implementation through not possible by standard quantum chemistry soft wares. The results shows I-V characteristics, Transport spectrum and Transport analysis can effectively tune the molecules works like a conventional semi-conductor based diodes, these results invoke to design the logic gates and logic circuits.
Kahraman, Ahmet
2002-01-01
In this study, design requirements for a dynamically viable, four-square type gear test machine are investigated. Variations of four-square type gear test machines have been in use for durability and dynamics testing of both parallel- and cross-axis gear set. The basic layout of these machines is illustrated. The test rig is formed by two gear pairs, of the same reduction ratio, a test gear pair and a reaction gear pair, connected to each other through shafts of certain torsional flexibility to form an efficient, closed-loop system. A desired level of constant torque is input to the circuit through mechanical (a split coupling with a torque arm) or hydraulic (a hydraulic actuator) means. The system is then driven at any desired speed by a small DC motor. The main task in hand is the isolation of the test gear pair from the reaction gear pair under dynamic conditions. Any disturbances originated at the reaction gear mesh might potentially travel to the test gearbox, altering the dynamic loading conditions of the test gear mesh, and hence, influencing the outcome of the durability or dynamics test. Therefore, a proper design of connecting structures becomes a major priority. Also, equally important is the issue of how close the operating speed of the machine is to the resonant frequencies of the gear meshes. This study focuses on a detailed analysis of the current NASA Glenn Research Center gear pitting test machine for evaluation of its resonance and vibration isolation characteristics. A number of these machines as the one illustrated has been used over last 30 years to establish an extensive database regarding the influence of the gear materials, processes surface treatments and lubricants on gear durability. This study is intended to guide an optimum design of next generation test machines for the most desirable dynamic characteristics.
Serkez, Svitozar; Saldin, Evgeni; Zagorodnov, Igor; Geloni, Gianluca
2013-01-01
We demonstrate that the output radiation characteristics of the European XFEL sources at nominal operation point can be easily made significantly better than what is currently reported in the TDRs of scientific instruments and X-ray optics. In fact, the output SASE characteristics of the baseline European XFEL have been previously optimized assuming uniform undulators at a nominal operating point of 5 kA peak current, without considering the potential of udulator tapering in the SASE regime. In order to illustrate this point, we analyze the case of an electron bunch with nominal parameters. Based on start-to-end simulations, we demonstrate that nonlinear undulator tapering allows one to achieve up to a tenfold increase in peak power and photon spectral density in the conventional SASE regime, without modification to the baseline design. The FEL code Genesis has been extensively used for these studies. In order to increase our confidence in simulation results, we cross-checked outcomes by reproducing simulatio...
Institute of Scientific and Technical Information of China (English)
田炜; 任新成
2013-01-01
The rough surface of snow and soil is simulated using a rough surface of exponential type. The transmission characteristics of electromagnetic wave through the soil surface covered by snow is investigated using the hybrid method based on the Method of Moment (MoM) and the Kirchhoff Approximation (KA). The snow surface and the soil surface are divided into an MoM region and a KA region by the hybrid method. The angular distribution of the transmission coefficient is obtained by the numerical calculation. The influences of the root-mean-square height of the snow surface and the soil surface, the type of the snow layer, the soil moisture, the thickness of the snow layer on the transmission coefficient are analyzed. It is indicated that the root-mean-square height of the snow surface, the type of the snow layer and the soil moisture have a considerable influence on the transmission coefficient,, but the influence of the root-mean-square height of the soil surface and the thickness of the snow layer can be neglected.%采用指数型粗糙面模拟实际的粗糙雪层和土壤表面,运用矩量法(MoM)结合基尔霍夫近似(KA)的混合算法研究了雪层覆盖土壤面的电磁波透射特征.混合算法将雪层表面划分在MoM区,土壤面划分在KA区,数值计算得到了透射系数的角分布曲线,分析了雪层和土壤表面的高度起伏均方根、雪层类型、土壤湿度、雪层厚度对透射系数的影响.结果表明,雪层表面高度起伏均方根、雪层类型、土壤湿度对透射系数有显著影响,而土壤表面高度起伏均方根和雪层厚度对透射系数影响较小.
Institute of Scientific and Technical Information of China (English)
胡纪滨; 何融; 彭增雄
2014-01-01
针对车辆常用机电复合无级传动的分速汇矩、分矩汇速和分速汇速3种功率耦合机构，分析了多行星排分流传动的转速、转矩和分流比特性，并对不同分流形式组合进行了分析。结果表明：多行星排分流特性与两行星排分流传动特性相同，分速汇矩式分流传动有一个机械点，在机械点之前分流比较小，适用于低速起步阶段；分矩汇速式分流有一个机械点，分流比成对称分布，传动比小于机械点时，成分流工况，效率高，适合于高速阶段。分速汇速式分流传动有两个机械点，在两个机械点之间分流比较小，适用于中高速阶段。对于多模式机电复合传动，低速起步采用分速汇矩式分流传动，中高速采用分速汇速式分流传动比较好，可实现电机无速差切换。%The characteristics of the speed,torque and split ratio of multi-planetary power split transmission are analyzed for input split,output split and compound split three power coupling mechanisms of vehicle electrome-chanical variable transmission ( EVT) , and the combinations of different power-split modes are analyzed. The re-sults show that the characteristic of multi-planetary power split transmission is the same as the dual-planetary one. The input split transmission has one mechanical point, before which the split ratio is relatively low, is suitable for low-speed start-up stage. The output split mode has one mechanical point with a symmetric distribution of split rati-o, and when transmission ratio is lower than mechanical point, the efficiency is high, suitable for high speed stage. The compound split has two mechanical points, between which the split ratio is relatively low with high efficiency, suitable for medium and high speed stages. For multi-mode EVT, it is recommended to adopt input split mode at low-speed start-up stage and adopt compound split mode at medium and high speed stages for achieving
Rulevskiy, V. M.; Bukreev, V. G.; Shandarova, E. B.; Kuleshova, E. O.; Shandarov, S. M.; Vasilyeva, Yu Z.
2017-02-01
A modeling problem of the power system, which provides an AC power transmission to a submersible device over the conducting rope, was considered. The power supply system units and their parameters are described. The system multi-dimensional mathematical model in the variables state space with regard to the nonlinear characteristic of system elements is proposed.
Transmission of Electric Energy Along Long Lines
Directory of Open Access Journals (Sweden)
Berzan V.P.
2009-08-01
Full Text Available Transmission of electric energy along long lines is examined and characteristics of the change of capacities at the beginning and at the end of a line are submitted: factor of capacity, efficiency of a transmission line, currents depending on length, parameters of a line and parameters of loading. Influence of losses upon the dynamics of instant values of voltages and currents in the opened and short-circuited long lines is investigated and effects of nonlinearity in such chains are revealed at a power supply from a sinusoidal source of voltage. It is shown, that the method of complex amplitudes is not always applicable for the calculation of modes in long lines.
Directory of Open Access Journals (Sweden)
Miroslav Kališnik
2011-05-01
Full Text Available In the introduction the evolution of methods for numerical density estimation of particles is presented shortly. Three pairs of methods have been analysed and compared: (1 classical methods for particles counting in thin and thick sections, (2 original and modified differential counting methods and (3 physical and optical disector methods. Metric characteristics such as accuracy, efficiency, robustness, and feasibility of methods have been estimated and compared. Logical, geometrical and mathematical analysis as well as computer simulations have been applied. In computer simulations a model of randomly distributed equal spheres with maximal contrast against surroundings has been used. According to our computer simulation all methods give accurate results provided that the sample is representative and sufficiently large. However, there are differences in their efficiency, robustness and feasibility. Efficiency and robustness increase with increasing slice thickness in all three pairs of methods. Robustness is superior in both differential and both disector methods compared to both classical methods. Feasibility can be judged according to the additional equipment as well as to the histotechnical and counting procedures necessary for performing individual counting methods. However, it is evident that not all practical problems can efficiently be solved with models.
Institute of Scientific and Technical Information of China (English)
Ren Ling; Chang Ben-Kang
2011-01-01
The resolution characteristic can be obtained by the modulation transfer function(MTF)of a GaAs/GaAlAs photocathode.After establishing the theoretical model of GaAs(100)-oriented atomic configuration and the formula for the ionized impurity scattering of the non-equilibrium carriers,this paper calculates the trajectories of photoelectrons in a photocathode.Thus the distribution of photoelectron spots on the emit-face is obtained,which is namely the point spread function.The MTF is obtained by Fourier transfer of the line spread function obtained from the point spread function.The MTF obtained from these calculations is shown to depend heavily on the electron diffusion length,and enhanced considerably by decreasing the electron diffusion length and increasing the doping concentration.Furthermore,the resolution is enhanced considerably by increasing the active-layer thickness,especially at high spatial frequencies.The best spatial resolution is 860 lp/mm,for the GaAs photocathode of doping concentration 1×1019cm-3,electron diffusion length 3.6 μm and the active-layer thickness 2 μm,under the 633-nm light irradiated. This research will contribute to the future improvement of the cathode's resolution for preparing a high performance GaAs photocathode,and improve the resolution of a low light level image intensifier.
Directory of Open Access Journals (Sweden)
Yongfeng Xu
2016-01-01
Full Text Available In order to reduce the investment and operation cost of distributed PV energy system, ice storage technology was introduced to substitute batteries for solar energy storage. Firstly, the ice storage air conditioning system (ISACS driven by distributed photovoltaic energy system (DPES was proposed and the feasibility studies have been investigated in this paper. And then, the theoretical model has been established and experimental work has been done to analyze the energy coupling and transferring characteristics in light-electricity-cold conversion process. In addition, the structure optimization analysis was investigated. Results revealed that energy losses were high in ice making process of ice slide maker with only 17.38% energy utilization efficiency and the energy efficiency and exergy efficiency of ISACS driven by DPES were 5.44% and 67.30%, respectively. So the immersed evaporator and cointegrated exchanger were adopted for higher energy utilization efficiency and better financial rewards in structure optimization. The COP and exergy efficiency of ice maker can be increased to 1.48 and 81.24%, respectively, after optimization and the energy utilization efficiency of ISACS driven by DPES could be improved 2.88 times. Moreover, ISACS has the out-of-the-box function of ordinary air conditioning system. In conclusion, ISACS driven by DPES will have good application prospects in tropical regions without power grid.
Sahimin, Norhidayu; Lim, Yvonne A L; Ariffin, Farnaza; Behnke, Jerzy M; Lewis, John W; Mohd Zain, Siti Nursheena
2016-11-01
A cross-sectional study of intestinal parasitic infections amongst migrant workers in Malaysia was conducted. A total of 388 workers were recruited from five sectors including manufacturing, construction, plantation, domestic and food services. The majority were recruited from Indonesia (n = 167, 43.3%), followed by Nepal (n = 81, 20.9%), Bangladesh (n = 70, 18%), India (n = 47, 12.1%) and Myanmar (n = 23, 5.9.2%). A total of four nematode species (Ascaris lumbricoides, Trichuris trichiura, Enterobius vermicularis and hookworms), one cestode (Hymenolepis nana) and three protozoan species (Entamoeba histolytica/dispar, Giardia sp. and Cryptosporidium spp.) were identified. High prevalence of infections with A. lumbricoides (43.3%) was recorded followed by hookworms (13.1%), E. histolytica/dispar (11.6%), Giardia sp. (10.8%), T. trichura (9.5%), Cryptosporodium spp. (3.1%), H. nana (1.8%) and E. vermicularis (0.5%). Infections were significantly influenced by socio-demographic (nationality), and environmental characteristics (length of working years in the country, employment sector and educational level). Up to 84.0% of migrant workers from Nepal and 83.0% from India were infected with intestinal parasites, with the ascarid nematode A. lumbricoides occurring in 72.8% of the Nepalese and 68.1% of the Indian population. In addition, workers with an employment history of less than a year or newly arrived in Malaysia were most likely to show high levels of infection as prevalence of workers infected with A. lumbricoides was reduced from 58.2% to 35.4% following a year's residence. These findings suggest that improvement is warranted in public health and should include mandatory medical screening upon entry into the country.
Sahimin, Norhidayu; Lim, Yvonne A. L.; Ariffin, Farnaza; Behnke, Jerzy M.; Lewis, John W.
2016-01-01
A cross-sectional study of intestinal parasitic infections amongst migrant workers in Malaysia was conducted. A total of 388 workers were recruited from five sectors including manufacturing, construction, plantation, domestic and food services. The majority were recruited from Indonesia (n = 167, 43.3%), followed by Nepal (n = 81, 20.9%), Bangladesh (n = 70, 18%), India (n = 47, 12.1%) and Myanmar (n = 23, 5.9.2%). A total of four nematode species (Ascaris lumbricoides, Trichuris trichiura, Enterobius vermicularis and hookworms), one cestode (Hymenolepis nana) and three protozoan species (Entamoeba histolytica/dispar, Giardia sp. and Cryptosporidium spp.) were identified. High prevalence of infections with A. lumbricoides (43.3%) was recorded followed by hookworms (13.1%), E. histolytica/dispar (11.6%), Giardia sp. (10.8%), T. trichura (9.5%), Cryptosporodium spp. (3.1%), H. nana (1.8%) and E. vermicularis (0.5%). Infections were significantly influenced by socio-demographic (nationality), and environmental characteristics (length of working years in the country, employment sector and educational level). Up to 84.0% of migrant workers from Nepal and 83.0% from India were infected with intestinal parasites, with the ascarid nematode A. lumbricoides occurring in 72.8% of the Nepalese and 68.1% of the Indian population. In addition, workers with an employment history of less than a year or newly arrived in Malaysia were most likely to show high levels of infection as prevalence of workers infected with A. lumbricoides was reduced from 58.2% to 35.4% following a year’s residence. These findings suggest that improvement is warranted in public health and should include mandatory medical screening upon entry into the country. PMID:27806046
Directory of Open Access Journals (Sweden)
Norhidayu Sahimin
2016-11-01
Full Text Available A cross-sectional study of intestinal parasitic infections amongst migrant workers in Malaysia was conducted. A total of 388 workers were recruited from five sectors including manufacturing, construction, plantation, domestic and food services. The majority were recruited from Indonesia (n = 167, 43.3%, followed by Nepal (n = 81, 20.9%, Bangladesh (n = 70, 18%, India (n = 47, 12.1% and Myanmar (n = 23, 5.9.2%. A total of four nematode species (Ascaris lumbricoides, Trichuris trichiura, Enterobius vermicularis and hookworms, one cestode (Hymenolepis nana and three protozoan species (Entamoeba histolytica/dispar, Giardia sp. and Cryptosporidium spp. were identified. High prevalence of infections with A. lumbricoides (43.3% was recorded followed by hookworms (13.1%, E. histolytica/dispar (11.6%, Giardia sp. (10.8%, T. trichura (9.5%, Cryptosporodium spp. (3.1%, H. nana (1.8% and E. vermicularis (0.5%. Infections were significantly influenced by socio-demographic (nationality, and environmental characteristics (length of working years in the country, employment sector and educational level. Up to 84.0% of migrant workers from Nepal and 83.0% from India were infected with intestinal parasites, with the ascarid nematode A. lumbricoides occurring in 72.8% of the Nepalese and 68.1% of the Indian population. In addition, workers with an employment history of less than a year or newly arrived in Malaysia were most likely to show high levels of infection as prevalence of workers infected with A. lumbricoides was reduced from 58.2% to 35.4% following a year's residence. These findings suggest that improvement is warranted in public health and should include mandatory medical screening upon entry into the country.
透射式特征X射线测厚仪研制%Exploiture Thickness Gauge of Transmission Characteristic X- ray
Institute of Scientific and Technical Information of China (English)
赵越; 屈国普; 郑贤利; 黄云
2011-01-01
论述了透射式特征X射线测厚原理,并对样机的硬件组成特征X射线发生装置、X射线探测器、数据处理器和监控软件进行了介绍.通过对测厚样机的实验测试,结果显示测量较薄物质时测厚仪反应灵敏,测量精度较高,相对误差在±5%以内,达到设计要求.%The theory of transmission characteristic X- ray measurement thickness are discussed,hardware including equipment for characteristic X - ray producing, X - ray detector, data processor and monitoring software are introduced. Properties of the thickness gauge are tested, results show thickness gauge is sensitive, higher accuracy when tested material is thin, relative error within 5 ％, according with design request.
Non-linear twist vibration of main transmission system of vertical rolling mill%立辊轧机主传动系统的扭振非线性分析
Institute of Scientific and Technical Information of China (English)
孟令启; 吴浩亮; 王建勋; 雷明杰
2009-01-01
In order to analyze and use the theory of main transmission of vertical rolling mill, a four-degree of freedom non-linear dynamical model on main transmission of vertical roller mill was established according to the actual parameters of the main transmission of 4200 vertical rolling mill. The bifurcation diagram, phase diagram and Poincare sections graph were obtained by Matlab software. The stability of periodic motion and the process of chaotic motion by ways of period doubling bifurcation were analyzed. The simulation results show that the movement of system is instable and leads to vibration Chaos when the driving force frequency is near the natural frequency of vertical rolling mill. Therefore, it should be avoided in the actual production. With the change of angular frequency, the system will change from the cycle movement to quasi-periodic motion. After a number of times the cycle, bifurcation eventually leads to the formation of chaos.%为了掌握立辊轧机主传动系统的扭振理论并且加以控制和利用,根据4200立辊轧机主传动系统的实际参数,建立立辊轧机主传动系统的4自由度非线性扭振模型,采用Matlab软件, 得到分岔图、相图和庞加莱截面,通过仿真分析其周期运动的稳定性以及通过倍周期分岔进入混沌的过程.仿真结果表明,当激振力频率与系统固有频率相近时,角位移增大,系统不稳定,在实际生产中要避免激振力频率与系统固有频率相近的工况;随着角频率的变化,系统由周期运动、准周期运动,经过一系列倍周期分岔最终导致混沌产生.
Directory of Open Access Journals (Sweden)
Valentino Anthony Simpao
2000-01-01
Full Text Available Herein an enhanced Hodgkin-Huxley (H-H type model of neuron dynamics is solved analytically via formal methods. Our model is a variant of an earlier one by M.A. Mahrous and H.Y. Alkahby [1]. Their modified model is realized by a hyperbolic quasi-linear diffusion operator with time-delay parameters; this compared to the original H-H model with standard parabolic quasi-linear diffusion operator and no time-delay parameters. Besides these features, the present model also incorporates terms describing signal dissipation into the background substrate (e.g., conductance to ground, making it more experimentally amenable. The solutions which results via the present scheme are of traveling-wave profile, which agree qualitatively with those observed in actual electro-physiological measurements made on the neural systems originally studied by H-H These results confirm the physiological soundness of the enhanced model and of the preliminary assumptions which motivated the present solution strategy; the comparison of the present results with actual electro-physiological data displays shall appear in later publications.
Ho, Kwok M
2017-08-31
Area under a receiver-operating-characteristic (AUROC) curve is widely used in medicine to summarize the ability of a continuous predictive marker to predict a binary outcome. This study illustrated how a U-shaped or inverted U-shaped continuous predictor would affect the shape and magnitude of its AUROC curve in predicting a binary outcome by comparing the ROC curves of the worst first 24-hour arterial pH values of 9549 consecutive critically ill patients in predicting hospital mortality before and after centering the predictor by its mean or median. A simulation dataset with an inverted U-shaped predictor was used to assess how this would affect the shape and magnitude of the AUROC curve. An asymmetrical U-shaped relationship between pH and hospital mortality, resulting in an inverse-sigmoidal ROC curve, was observed. The AUROC substantially increased after centering the predictor by its mean (0.611 vs 0.722, difference = 0.111, 95% confidence interval [CI] 0.087-0.135), and was further improved after centering by its median (0.611 vs 0.745, difference = 0.133, 95%CI 0.110-0.157). A sigmoidal-shaped ROC curve was observed for an inverted U-shaped predictor. In summary, a non-linear predictor can result in a biphasic-shaped ROC curve; and centering the predictor can reduce its bias towards null predictive ability.
Srivastava, Ambrish Kumar
2016-01-01
Alkalides possess enhanced nonlinear optical (NLO) responses due to localization of excess electrons on alkali metals. We have proposed a new class of alkalides by sandwiching alkali atoms (M) between two Li3O superalkali clusters at MP2/6-311++G(d,p) level. We notice a competition between alkalide characteristics and NLO properties in OLi3-M-Li3O (M=Li, Na and K) isomers. For instance, the atomic charge on M (qM) in D2h structure is -0.58e for M=Li and its first static mean hyperpolarizablity (\\b{eta}o) is 1 a.u., but in C2v structure, qM=-0.12e and \\b{eta}o= 3.4*103 a.u. More interestingly, the \\b{eta}o value for M=K (C2v) increases to 1.9*104 a.u. in which qM=0.24e. These findings may provide new insights into the design of alkalides, an unusual class of salts and consequently, lead to further researches in this direction.
Nercessian, Shahan C; Panetta, Karen A; Agaian, Sos S
2013-09-01
Image enhancement is a crucial pre-processing step for various image processing applications and vision systems. Many enhancement algorithms have been proposed based on different sets of criteria. However, a direct multi-scale image enhancement algorithm capable of independently and/or simultaneously providing adequate contrast enhancement, tonal rendition, dynamic range compression, and accurate edge preservation in a controlled manner has yet to be produced. In this paper, a multi-scale image enhancement algorithm based on a new parametric contrast measure is presented. The parametric contrast measure incorporates not only the luminance masking characteristic, but also the contrast masking characteristic of the human visual system. The formulation of the contrast measure can be adapted for any multi-resolution decomposition scheme in order to yield new human visual system-inspired multi-scale transforms. In this article, it is exemplified using the Laplacian pyramid, discrete wavelet transform, stationary wavelet transform, and dual-tree complex wavelet transform. Consequently, the proposed enhancement procedure is developed. The advantages of the proposed method include: 1) the integration of both the luminance and contrast masking phenomena; 2) the extension of non-linear mapping schemes to human visual system inspired multi-scale contrast coefficients; 3) the extension of human visual system-based image enhancement approaches to the stationary and dual-tree complex wavelet transforms, and a direct means of; 4) adjusting overall brightness; and 5) achieving dynamic range compression for image enhancement within a direct multi-scale enhancement framework. Experimental results demonstrate the ability of the proposed algorithm to achieve simultaneous local and global enhancements.
Institute of Scientific and Technical Information of China (English)
刘升; 孙冬野; 秦大同
2015-01-01
重型车湿式桥传动系统能量流动与损耗研究是车辆经济性、安全性及动力性的基础。现有研究主要简单分析单工况下齿轮箱的能量损耗，缺乏复杂工况下基于人车路的传动系统能量流耗精细综合研究。针对典型重型车辆循环作业下的湿式桥传动系统能量流耗进行综合分析，建立不同能量损耗类型的数学模型。考虑车辆循环作业能量流耗影响因素，基于键合图理论分析总成及系统能量流耗情况后，建立整个传动系统的能量流耗模型。此动力学模型与实车试验数据结合不但可以研究一般工况下的人车路湿式桥非线性能量流耗，还可以分析驱动滑转、制动滑移、转弯、轮荷及重心转移等复杂工况，这为今后研究和精确实车复杂工况下的能量流耗情况提供了一套可行的方法。%The study on transmission energy flows and loss for the wet axle in the heavy vehicle are the base of economy, security, power performance of vehicle. The existing researches focus on gear box energy loss under simple operating model, and the fine comprehensive study of transmission system energy flows and loss based on diver vehicle road under complicated operating model is scarce. The energy flows and loss of transmission system in wet axle under typical cycle operation of heavy vehicle are analyzed, and the mathematical models of different energy loss style are built. The influencing factors of energy flows and loss under vehicle cycle operating are considered, after the assemblies and system energy flows and loss are analyzed based on bond graph theory, the total transmission system energy flows and loss models are built in the end. The nonlinear energy flows and loss in wet axle on driver vehicle road under general operating model can be analyzed on the combination of this dynamic model with vehicle experimental data, even under complicated operating model as drive slipping, brake
Jentes, Emily S; Han, Pauline; Gershman, Mark D; Rao, Sowmya R; LaRocque, Regina C; Staples, J Erin; Ryan, Edward T
2013-05-01
Yellow fever (YF) vaccine-associated serious adverse events and changing YF epidemiology have challenged healthcare providers to vaccinate only travelers whose risk of YF during travel is greater than their risk of adverse events. We describe the travel characteristics and YF vaccine use among US travelers visiting Global TravEpiNet clinics from January of 2009 to March of 2011. Of 16,660 travelers, 5,588 (34%) had itineraries to areas with risk of YF virus transmission. Of those travelers visiting one country with YF risk (N = 4,517), 71% were vaccinated at the visit, and 20% were presumed to be immune from prior vaccination. However, travelers visiting friends and relatives (odds ratio [OR] = 2.57, 95% confidence interval [95% CI] = 1.27-5.22) or going to Nigeria (OR = 3.01, 95% CI = 1.37-6.62) were significantly more likely to decline vaccination. To optimize YF vaccine use, clinicians should discuss an individual's risk-benefit assessment of vaccination and close knowledge gaps regarding vaccine use among at-risk populations.
Bloembergen, Nicolaas
1996-01-01
Nicolaas Bloembergen, recipient of the Nobel Prize for Physics (1981), wrote Nonlinear Optics in 1964, when the field of nonlinear optics was only three years old. The available literature has since grown by at least three orders of magnitude.The vitality of Nonlinear Optics is evident from the still-growing number of scientists and engineers engaged in the study of new nonlinear phenomena and in the development of new nonlinear devices in the field of opto-electronics. This monograph should be helpful in providing a historical introduction and a general background of basic ideas both for expe
Different Types of Coding Input Data In Optical Transmission Systems
Directory of Open Access Journals (Sweden)
Ján Ružbarský
2016-12-01
Full Text Available Optical fiber transmission systems are currently the most widely used transmission media. Their development in time had improved their characteristics to such an extent that they gradually replaced very popular copper cable connections. Inspite of that optical fibers still have not reached perfection and constant improvement is needed. Apart from notable advantages such as large data transfer, few numbers of repeaters required on the transmission path or higher safety of transmitted data, optical fiber has also drawbacks that include not sufficient purity optical fibers, fiber fragility and also higher proclivity to nonlinear effects. Weaknesses of optical systems can be depressed by e.g. a selection of an appropriate laser, a proper combination of materials used for fiber production during the manufacture process, or even by using an encryption of transmitted data. This article is focused on the comparison of optical signal properties in various source encoding types of input data.
Nonlinear phased array imaging
Croxford, Anthony J.; Cheng, Jingwei; Potter, Jack N.
2016-04-01
A technique is presented for imaging acoustic nonlinearity within a specimen using ultrasonic phased arrays. Acoustic nonlinearity is measured by evaluating the difference in energy of the transmission bandwidth within the diffuse field produced through different focusing modes. The two different modes being classical beam forming, where delays are applied to different element of a phased array to physically focus the energy at a single location (parallel firing) and focusing in post processing, whereby one element at a time is fired and a focused image produced in post processing (sequential firing). Although these two approaches are linearly equivalent the difference in physical displacement within the specimen leads to differences in nonlinear effects. These differences are localized to the areas where the amplitude is different, essentially confining the differences to the focal point. Direct measurement at the focal point are however difficult to make. In order to measure this the diffuse field is used. It is a statistical property of the diffuse field that it represents the total energy in the system. If the energy in the diffuse field for both the sequential and parallel firing case is measured then the difference between these, within the input signal bandwidth, is largely due to differences at the focal spot. This difference therefore gives a localized measurement of where energy is moving out of the transmission bandwidth due to nonlinear effects. This technique is used to image fatigue cracks and other damage types undetectable with conventional linear ultrasonic measurements.
Modeling and Simulation of Nonlinear Transmission Lines
2010-01-01
consisting of parallel-plate waveguides in which layers of ferroelectric material (specifically, barium strontium titanate , or BST) alternated with...permits; meanwhile, the basic analysis of the NLTL performance benefits greatly from the feasibility of writing transparent software that is easily...where the parameters t, 0, and are used to fit the data. The values of these parameters they found for their particular BST samples
Transmission line model for nanoelectronics
Directory of Open Access Journals (Sweden)
Nelin E. A.
2009-08-01
Full Text Available Analytical expressions for resonant parametres and characteristics of typical barrier nanoelectronic structures have been received on the basis of the transmission line model. Characteristics illustrating the efficiency of such approach are presented in the article.
Gratz, M.; Tschöpe, A.
2017-01-01
Ni nanorods with an average length transmission of nanorod colloidal dispersions in alternating magnetic fields were measured and analyzed with the objective of comparing the intrinsic Brownian relaxation times obtained with the two methods. The different physical origin of the measured signal, related to different moments of the orientation distribution function, and the non-linear effects expected for the large magnetic moments of the Ni nanorods at common field amplitudes required a comprehensive modelling. The time-dependent magnetization and optical transmission in ac magnetic fields was derived by numerical solution of the Fokker-Planck equation. The simulated time-dependent magnetization and optical transmission at a given frequency and field amplitude were analyzed analogous to experimental data to determine characteristic relaxation frequencies. Empirical relationships were derived which enabled extraction of the intrinsic Brownian relaxation time from the characteristic frequencies measured in the non-linear regime. Despite large differences in the characteristic frequencies obtained from magnetization and optical transmission measurements, the retrieved intrinsic Brownian relaxation times were found to agree well. The potential of ac magnetic field-dependent optical transmission for biosensing applications was demonstrated by monitoring the adsorption of the protein gelatine on the nanorod labels.
Institute of Scientific and Technical Information of China (English)
李同杰; 朱如鹏; 鲍和云; 项昌乐; 刘辉
2011-01-01
建立行星齿轮系扭转非线性振动模型,模型中考虑了行星齿轮系各齿轮副间的时变啮合刚度、齿侧间隙以及综合传递误差等非线性因素；推导出系统的量纲一振动微分方程,采用数值积分方法研究行星齿轮的运动特性随转速以及齿侧间隙等参数的分岔特性,结合Poincaré图形分析,研究转速、啮合阻尼以及齿侧间隙等参数对系统分岔特性的影响.结果发现,随着转速的逐渐增大,系统会通过激变途径进入到混沌运动,而随着齿侧间隙的逐渐增大,系统会通过倍周期分岔途径进入到混沌.阻尼过小将会导致行星齿轮系统的稳态运动由短周期运动向复杂运动转变.齿侧间隙是影响系统运动分岔特性的重要因素,但是影响范围主要限于量纲一齿侧间隙大于3.5的大间隙区段.%A nonlinear torsional vibration model of a planetary gear train with errors of transmission, time varying meshing stiffness and gear backlashes is established and dimensionless equations of the system are derived. The solution of the equations is carried out by using the method of numerical integration. By comparing with Poincare maps and bifurcation diagrams, the bifurcation properties of the system are studied. The influences of some bifurcation parameters such as rotational speed, damping coefficient and gear backlashes on the bifurcation properties of the system are assessed. The study results reveal that the system's motion state will change into chaos in the way of crisis as speed increase and period doubling bifurcation is the way to chaos as backlashes increase. A smaller damping coefficient will make the system's periodic motion state change into complex state. Gear backlashes have a strong impact on the system's bifurcation characteristic when dimensionless the backlashes is bigger than 3.5.
Institute of Scientific and Technical Information of China (English)
钟艳春; 杨庆俊; 包钢
2011-01-01
The nonlinear dynamics characteristic of pneumatic vibration isolation system with a multi-frequency excitation was studied with the method of nonlinear dynamics. First, relative load curve of an air spring under a certain initial pressure was obtained by test, and based on the test data, a cube polynomial equation was obtained by means of nonlinear polynomial curve fitting according to the equilibrium heights of the air spring. Then, the nonlinear model of pneumatic vibration isolation system with a multi-frequency excitation was built and nonlinear dynamics equation was obtained according to nonlinear restoring force of the air spring. Next, the method of multiple scales was used to solve the nonlinear dynamics equation. Finally, combination resonance of pneumatic vibration isolation system with a multi-frequency excitation was analyzed and influences of the nonlinear parameter to the system were discussed. The results show that when combination frequencies are near the linearized natural frequency, combination resonance becomes strong. Cube nonlinear parameter directly influences nonlinear characteristic of the system, the greater the excitation amplitude, the more obvious of the nonlinear characteristic.%运用非线性动力学的方法研究气动隔振系统在多个频率激励下的非线性动力学特性.通过试验的方法得到空气弹簧在一定初始压力下的相对载荷曲线,以空气弹簧工作高度为自变量,用三次多项式对该曲线进行非线性拟合,得到弹簧非线性恢复力与工作高度的三次多项式表达式.建立气动隔振系统在3个激励频率下的非线性模型,根据弹簧的非线性恢复力,得到系统的非线性动力学方程.运用多尺度法对该非线性动力学方程进行求解,分析3个频率共同作用下的组合共振,讨论各非线性参数对系统的影响.研究结果表明:当组合频率接近系统线性化固有频率时,系统具有很强的组合共振;三次非线性
Effect of Tooth Profile Modification on Vibration of Power Split Gear Transmission System
Institute of Scientific and Technical Information of China (English)
He Lin
2016-01-01
Based on Newton's second law, the bend⁃torsion⁃shaft coupling nonlinear dynamic model and equations of power split gear transmission system are established. According to the principle of tooth profile modification, the tooth profile modification is considered as time⁃varying gear backlash function acting along the line of action. Then the dynamic functions are solved by using Runge⁃Kutta numerical method. After analyzing the effect of tooth profile modification quantity( TPMQ) and relative tooth profile modification length( TPML) to the nonlinear dynamic characteristics of power split gear transmission, the following conclusions are drawn:①The TPMQ of a certain stage transmission affects the vibration of its own stage more significantly than the other stage, and the coupling effect between two stages can be ignored usually in the modification design;②If the first stage TPMLs are less than 0.3, the influence of the first stage TPMLs to the first stage transmission vibration is much more greatly than the influence of the second stage TPMLs to the first stage transmission vibration, or else both the first and second stage TPMLs affect the first stage transmission vibration largely. The same is true for the second stage TPMLs, and the cutoff value is 0. 2; ③The TPMQ affects the vibration of power split gear transmission system more principally than the TPML, and should be top⁃priority in the modification design.
2016-07-01
Advanced Research Projects Agency (DARPA) Dynamics-Enabled Frequency Sources (DEFYS) program is focused on the convergence of nonlinear dynamics and...Early work in this program has shown that nonlinear dynamics can provide performance advantages. However, the pathway from initial results to...dependent nonlinear stiffness observed in these devices. This work is ongoing, and will continue through the final period of this program . Reference 9
Neurodynamics: nonlinear dynamics and neurobiology.
Abarbanel, H D; Rabinovich, M I
2001-08-01
The use of methods from contemporary nonlinear dynamics in studying neurobiology has been rather limited.Yet, nonlinear dynamics has become a practical tool for analyzing data and verifying models. This has led to productive coupling of nonlinear dynamics with experiments in neurobiology in which the neural circuits are forced with constant stimuli, with slowly varying stimuli, with periodic stimuli, and with more complex information-bearing stimuli. Analysis of these more complex stimuli of neural circuits goes to the heart of how one is to understand the encoding and transmission of information by nervous systems.
Institute of Scientific and Technical Information of China (English)
范毅
2015-01-01
行星齿轮机构的动力特性分析与研究是自动变速器设计的重要过程。针对5个独立运动构件的双排行星齿轮机构自动变速器，运用整体矢量法分析了该变速器的动力传递路线。根据三角形相似原理计算了各挡位传动比。结合转速矢量图，进一步分析了此类变速器的升降挡过程。运用整体矢量法能定性分析自动变速器动力传递特性及定量计算各挡位传动比及各元件转速大小。%It is a key process for the automatic transmission design to study and analyze the dynamic characteristics of the planetary gear mechanism. Applying whole vector method, the paper analyzes the power transmission route of the double-row planetary gear mechanism’s automatic transmissions on five independent motion components. The transmission ratios under dif-ferent gears are also calculated according to the triangle similarity theory. Combining with the speed vector graph , the lifting gear process of such kinds of automatic transmission is further analyzed. The whole vector method is of great help to qualitative analy-sis of the automatic transmission’s power transmission characteristics and quantitative calculation of transmission ratio and ele-ment speed.
Nonlinear response studies and corrections for a liquid crystal spatial light modulator
Indian Academy of Sciences (India)
Ravinder Kumar Banyal; B Raghavendra Prasad
2010-06-01
The nonlinear response of light transmission characteristics of a liquid crystal (LC) spatial light modulator (SLM) is studied. The results show that the device exhibits a wide range of variations with different control parameters and input settings. Experiments were performed to obtain intensity modulation that is best described by either power-law or sigmoidal functions. Based on the inverse transformation, an appropriate pre-processing scheme for electrically addressed input gray-scale images, particularly important in several optical processing and imaging applications, is suggested. Further, the necessity to compensate the SLM image nonlinearities in a volume holographic data storage and retrieval system is demonstrated.
Nayfeh, Ali Hasan
1995-01-01
Nonlinear Oscillations is a self-contained and thorough treatment of the vigorous research that has occurred in nonlinear mechanics since 1970. The book begins with fundamental concepts and techniques of analysis and progresses through recent developments and provides an overview that abstracts and introduces main nonlinear phenomena. It treats systems having a single degree of freedom, introducing basic concepts and analytical methods, and extends concepts and methods to systems having degrees of freedom. Most of this material cannot be found in any other text. Nonlinear Oscillations uses sim
Yoshida, Zensho
2010-01-01
This book gives a general, basic understanding of the mathematical structure "nonlinearity" that lies in the depths of complex systems. Analyzing the heterogeneity that the prefix "non" represents with respect to notions such as the linear space, integrability and scale hierarchy, "nonlinear science" is explained as a challenge of deconstruction of the modern sciences. This book is not a technical guide to teach mathematical tools of nonlinear analysis, nor a zoology of so-called nonlinear phenomena. By critically analyzing the structure of linear theories, and cl
Nanda, Sudarsan
2013-01-01
"Nonlinear analysis" presents recent developments in calculus in Banach space, convex sets, convex functions, best approximation, fixed point theorems, nonlinear operators, variational inequality, complementary problem and semi-inner-product spaces. Nonlinear Analysis has become important and useful in the present days because many real world problems are nonlinear, nonconvex and nonsmooth in nature. Although basic concepts have been presented here but many results presented have not appeared in any book till now. The book could be used as a text for graduate students and also it will be useful for researchers working in this field.
Fast Numerical Nonlinear Fourier Transforms
Wahls, Sander
2014-01-01
The nonlinear Fourier transform, which is also known as the forward scattering transform, decomposes a periodic signal into nonlinearly interacting waves. In contrast to the common Fourier transform, these waves no longer have to be sinusoidal. Physically relevant waveforms are often available for the analysis instead. The details of the transform depend on the waveforms underlying the analysis, which in turn are specified through the implicit assumption that the signal is governed by a certain evolution equation. For example, water waves generated by the Korteweg-de Vries equation can be expressed in terms of cnoidal waves. Light waves in optical fiber governed by the nonlinear Schr\\"dinger equation (NSE) are another example. Nonlinear analogs of classic problems such as spectral analysis and filtering arise in many applications, with information transmission in optical fiber, as proposed by Yousefi and Kschischang, being a very recent one. The nonlinear Fourier transform is eminently suited to address them ...
Institute of Scientific and Technical Information of China (English)
陈会涛; 吴晓铃; 秦大同; 杨军
2013-01-01
考虑时变啮合刚度、齿侧间隙等因素的影响,建立了单对齿轮系统纯扭转非线性动力学模型.将齿轮综合传递误差波动和外部载荷作为随机变量,利用数值仿真方法对系统模型进行了求解,通过统计分析得到了系统各响应量和动态啮合力的统计特征.结果表明:外部激励的随机性对齿轮系统振幅和动态啮合力的影响比综合传递误差波动随机时明显；综合传递误差及外部激励随机波动离散程度的增加会导致系统振幅和动态啮合力不稳定性加剧.%A nonlinear dynamic model of spur gear pair system was developed with consideration of time-varying mesh stiffness and backlash. The fluctuation of transmission error and external load were treated as random variables, then, the nonlinear dynamic model of spur gear pair system was solved using the numerical emulation method. The statistical properties of vibration displacement and dynamic engaging force of gear pairs were obtained through the statistics analysis of the simulation results. The statistic analyses show that; the random fluctuation of external excitation have a greater impact on the dynamic response of gear system than the random fluctuation of transmission error. The instability of vibration amplitude and dynamic meshing force of the system increases with the increase of the degree of dispersion of transmission error and external excitation.
Energy Technology Data Exchange (ETDEWEB)
You, Seung Han [Hyundai Motor Company, Seoul (Korea, Republic of); Hahn, Jin Oh [University of Alberta, Edmonton (Canada)
2012-05-15
By virtue of its ease of operation compared with its conventional manual counterpart, automatic transmissions are commonly used as automotive power transmission control system in today's passenger cars. In accordance with this trend, research efforts on closed-loop automatic transmission controls have been extensively carried out to improve ride quality and fuel economy. State-of-the-art power transmission control algorithms may have limitations in performance because they rely on the steady-state characteristics of the hydraulic actuator rather than fully exploit its dynamic characteristics. Since the ultimate viability of closed-loop power transmission control is dominated by precise pressure control at the level of hydraulic actuator, closed-loop control can potentially attain superior efficacy in case the hydraulic actuator can be easily incorporated into model-based observer/controller design. In this paper, we propose to use a recurrent neural network (RNN) to establish a nonlinear empirical model of a cascade hydraulic actuator in a passenger car automatic transmission, which has potential to be easily incorporated in designing observers and controllers. Experimental analysis is performed to grasp key system characteristics, based on which a nonlinear system identification procedure is carried out. Extensive experimental validation of the established model suggests that it has superb one-step-ahead prediction capability over appropriate frequency range, making it an attractive approach for model-based observer/controller design applications in automotive systems.
Institute of Scientific and Technical Information of China (English)
孙建东; 雷红; 刘自萍; 田娥; 付文宇
2012-01-01
介绍一种具有自主知识产权的新型脉动无级变速器,讨论了该变速器的工作原理,分析了该变速器的主要运动特性,并与现有的其他类型的脉动无级变速器进行对比分析.分析结论表明,该变速器具有比较优异的运动性能.%Describes a new type of pulse continuously variable transmission; discuss the working principle, analyzes the major sports characteristics, and compare with other types of current pulse Continuously Variable Transmission ( CVT). The results show that the transmission has a relatively superior sports performance.
Reconfigurable nonreciprocity with nonlinear Fano diode
Xu, Yi; Miroshnichenko, Andrey E.
2013-01-01
We propose a dynamically tunable nonreciprocal response for wave propagations by employing nonlinear Fano resonances. We demonstrate that transmission contrast of waves propagation in opposite directions can be controlled by excitation signal. In particular, the unidirectional transmission can be flipped at different times of a pulse, resembling a diode operation with {\\em dynamical reconfigurable nonreciprocity}. The key mechanism is the interaction between the linear and nonlinear Fano reso...
Photonic surfaces for designable nonlinear power shaping
Energy Technology Data Exchange (ETDEWEB)
Biswas, Roshni, E-mail: rbiswas@usc.edu; Povinelli, Michelle L. [Ming Hsieh Department of Electrical Engineering, University of Southern California, Los Angeles, California 90089 (United States)
2015-02-09
We propose a method for designing nonlinear input-output power response based on absorptive resonances of nanostructured surfaces. We show that various power transmission trends can be obtained by placing a photonic resonance mode at the appropriate detuning from the laser wavelength. We demonstrate our results in a silicon photonic crystal slab at a laser wavelength of 808 nm. We quantify the overall spectral red shift as a function of laser power. The shift results from absorptive heating and the thermo-optic effect. We then demonstrate devices with increasing, decreasing, and non-monotonic transmission as a function of laser power. The transmission changes are up to 7.5 times larger than in unpatterned silicon. The strong nonlinear transmission is due to a combination of resonantly enhanced absorption, reduced thermal conductivity, and the resonant transmission lineshape. Our results illustrate the possibility of designing different nonlinear power trends within a single materials platform at a given wavelength of interest.
Energy Technology Data Exchange (ETDEWEB)
Ataei, Nader
2006-05-09
Different types of exciter are used for voltage supply to the synchronous generators of power stations depending on the required power and design. The exciter system of the generator, which as a rule consists syncronous motors and commutators, is commonly modeled in conventional models by control units with nonlinear characteristics which do not give an accurate picture of the dynamic processes inside the exciter motor. It was not possible to assess the component loads of the exciter components and the physical characteristics within the exciter system. In this study, a brushless exciter for the grid-connected synchronous generator was investigated which consists of two synchronous motors as primary and secondary exciter and two commutator bridges. A dynamic simulation model was developed for calculating the interactions between the grid, generator and exciter unit in consideration of electromagnetic and galvanic coupling. For this, the normal control units were replaced by physical components of the exciter system, i.e. electric exciter motors and commutators. The study was carried out using an enhanced version of the Siemens NETOMAC software, which provided information on the loads on the exciter components in case of internal and external failures. In particular, loads in coils and commutators were calculated that could not be measured before. The findings enable more accurate dimensioning of the exciter unit making it more fail-safe, and the protective systems can be adjusted more accurately. One important result of the investigation was the identification of all dynamic processes going on between the exciter motors, commutators, generator and grid induced by external and internal failures. (orig.) [German] Zur Spannungsversorgung der Synchrongeneratoren in Kraftwerken werden je nach Leistungsanforderung und Baukonzept unterschiedliche Erregereinrichtungen verwendet. Das Erregersystem des Generators, das in der Regel aus Erregersynchronmaschinen und
Institute of Scientific and Technical Information of China (English)
陈永华; 唐冠军; 宋晓芳; 李雪明
2015-01-01
风电送出线路不满足N-1安全约束时，任意一条线路跳闸都会导致其他线路出现过载。针对集群式风电并网的特点，首先分析风电机组低电压穿越(LVRT)能力、风电短时出力波动对传统过载控制方案的影响，并提出针对性建议。在此基础上，进一步提出考虑风电出力变化趋势的过载切机方案，通过数值方法分析各风电场的出力变化趋势，动态优化选择切机对象，使得切机措施更加高效，减小风电送出线路再次发生过载的概率，从而保障风电外送通道的安全性。%Any line outage will lead to other lines overloading when the wind farm grid connection lines does not meet the N-1 security constraints.Considering cluster grid connected wind farms characteristics,this paper analyzes the impact of the wind farm”s low voltage ride through (LVRT) capability and short-term fluctuations on the traditional overload control scheme first,and then proposes a new generator tripping scheme on overload considering the trend of wind farm output.The trend is analyzed by using numerical method,optimizing tripping machine obj ect dynamically,making overload control more efficient and reducing the chance of wind farm grid connection lines overloading.The method will enhance the wind farms transmission corridor safety and reliability. This work is supported by National Key Technologies R&D Program(No.2012BAA15G00)and State Grid Corporation of China,Major Projects on Planning and Operation Control of Large Scale Grid(No.SGCC-MPLG003-2012).
Energy Technology Data Exchange (ETDEWEB)
Zhang, G.M. [China Center of Advanced Science and Technology (CCAST), Beijing, BJ (China)]|[Suzhou Univ. (China). Dept. of Physics
1996-04-01
In this note we consider the geometrical effects of a percolating system on the nonlinear transport properties in a superconductor-normal conductor nonlinear resistor network. For realistic composites, the nonlinearity may play an important role in the electrical transport phenomena. A typical example consists of studying a nonlinear composite medium in which an inclusion with nonlinear current-field (J-E) characteristics is randomly embedded in a host with either linear or nonlinear J-E response. For such a system, substantial progress in studies of the effective nonlinear response has been made in the past few years. 24 refs.
Institute of Scientific and Technical Information of China (English)
陈文仙; 陈乾宏; 张惠娟
2015-01-01
主要研究了电磁共振式无线电能传输(WPT)系统的距离传输特性以及提高传输距离的途径。利用互感模型解释了电磁共振式 WPT 系统的工作原理，同时，通过理论求解得到了系统关于距离的传输特性表达式。在此基础上，进一步研究了提高系统传输距离的途径。研究表明，电磁共振式 WPT 系统存在电压增益与输出功率特性的最优距离点，同时系统高频化是提高传输距离与传输效率的有效途径。最后，搭建了一个电磁共振式 WPT 实验装置进行实验验证，实验结果与理论分析结果一致。%This paper mainly studies the distance transmission characteristics of the magnetic resonance wireless power transmission system and methods to improve the transmission distance.The mutual model is used to explain the operation principle of magnetic resonance wireless power transmission system,while the expression between the transfer characteristic and the distance is obtained by theoretical analysis on the system.On this basis,further research aimed to improve the system transmission distance is done.It has been found that there is an optimal distance point in the magnetic resonance wireless power transmission system,and improving the resonance frequency of the system is an effective way to increase transmission distance.Finally,a magnetic resonance wireless power transmission system is set up for experimental verification.The experimental results are in agreement with theoretical analysis.
Zhu, Hong-Ming; Pen, Ue-Li; Chen, Xuelei; Yu, Hao-Ran
2016-01-01
We present a direct approach to non-parametrically reconstruct the linear density field from an observed non-linear map. We solve for the unique displacement potential consistent with the non-linear density and positive definite coordinate transformation using a multigrid algorithm. We show that we recover the linear initial conditions up to $k\\sim 1\\ h/\\mathrm{Mpc}$ with minimal computational cost. This reconstruction approach generalizes the linear displacement theory to fully non-linear fields, potentially substantially expanding the BAO and RSD information content of dense large scale structure surveys, including for example SDSS main sample and 21cm intensity mapping.
Boyd, Robert W
2013-01-01
Nonlinear Optics is an advanced textbook for courses dealing with nonlinear optics, quantum electronics, laser physics, contemporary and quantum optics, and electrooptics. Its pedagogical emphasis is on fundamentals rather than particular, transitory applications. As a result, this textbook will have lasting appeal to a wide audience of electrical engineering, physics, and optics students, as well as those in related fields such as materials science and chemistry.Key Features* The origin of optical nonlinearities, including dependence on the polarization of light* A detailed treatment of the q
Institute of Scientific and Technical Information of China (English)
宋娟; 王立德; 严翔; 申萍
2012-01-01
In accordance with the theory of transmission line, the distribution parameters channel model of twisted pair wires was proposed. The numerical model parameters of the MVB physical layer medium were deduced by numerical fitting thourgh analysis of numerical model parameters of common twisted pair wires. The RLCG numerical model was established, and simulation of the frequency characteristics of R, L, C and G was performed. Spectrum characteristics and characteristic impedances of the transmission line were obtained; and the attenuation characteristics, available bandwidth and channel capacity in the case of reliable operation were also got. Finally the correctness of the model was verified by the experimental results. This research lays a foundation for further research on the signal transmission characteristics of special train twisted pair wires.%根据传输线理论,给出双绞线的分布参数信道模型.通过分析普通双绞线的参数,采用数值拟合的方法推导出MVB物理层介质的数值模型参数,建立RLCG数值模型,并对R、L、C和G的频率特性进行仿真分析,得出传输线的频谱特性、特征阻抗、系统可靠运行情况下的衰减特性、可用带宽、信道容量等,最终实验验证了模型的正确性,为进一步研究列车专用双绞线的信号传输特性提供了支持.
Ruszczynski, Andrzej
2011-01-01
Optimization is one of the most important areas of modern applied mathematics, with applications in fields from engineering and economics to finance, statistics, management science, and medicine. While many books have addressed its various aspects, Nonlinear Optimization is the first comprehensive treatment that will allow graduate students and researchers to understand its modern ideas, principles, and methods within a reasonable time, but without sacrificing mathematical precision. Andrzej Ruszczynski, a leading expert in the optimization of nonlinear stochastic systems, integrates t
Webbe, G.
1965-01-01
Accurate quantitative assessment is essential to any study of disease transmission; in relation to the transmission of bilharziasis the most important characteristics that have to be determined include density, reproduction and mortality rates, the age and sex structure of the population, dispersion and the intrinsic rate of natural increase (the biotic potential). The author discusses techniques that have been developed to yield this and other information and stresses the need to evaluate such techniques objectively. Some basic principles of population ecology are defined and discussed in relation to the control of transmission. It is considered that laboratory studies can be usefully carried on in conjunction with field work but that they cannot be substituted for field investigations in determining the parameters of bilharziasis transmission for a given area. PMID:5294586
Institute of Scientific and Technical Information of China (English)
李鑫; 张石静; 许南绍
2012-01-01
针对电动汽车对传动系的节能要求较高,提出了一种可搭载于电动汽车上的新型行星齿轮无级变速器(planetary gear continuously variable transmission,P-CVT),从P-CVT的机械结构推导出其基本构件间的转速关系和扭矩的关系,并从能量守恒的角度对这两个关系进行了理论验证,最后通过ADAMS工具对一个具体实例进行动力学仿真.仿真结果证明了该变速器的输入、输出扭矩与速比之间并无直接关系,可以实现无级变速条件下的高速大扭矩输出.具有能效较高、调速平稳、控制简单的特点.%As far as the energy-saving requirements of the Transmission system carried in electric vehicles(EV) is concerned, this paper proposes a new-type planetary gear continuously variable transmission(P-CVT) carried in EV. The relations of the rotation speed and the torque among its basic components are derived by analyzing the Mechanical structure of P-CVT,and these two relations are proved from the perspective of energy conservation. Finally, dynamics simulation has been done on the relations derived above with ADAMS. The simulation results show that the input and output torque of the transmission do not have contact with the speed ratio directly, and high-speed and large-torque output can be achieved under conditions of continuously variable transmission. This transmission has characteristics of high energy-efficiency, stable adjustment, and simple control.
Meijer, H.J.M; Baan, G.C.; Huijing, P.A.
2006-01-01
Aim: Effects of submaximal stimulation frequencies on myofascial force transmission were investigated for rat anterior crural muscles with all motor units activated. - Methods: Tibialis anterior and extensor hallucis longus (TAEHL) muscles were kept at constant muscle-tendon complex length, but exte
Non-linear – characteristics of doped Sn1–TiO2 (0.0 < < 0.25) system
Indian Academy of Sciences (India)
V Ravi; S K Date
2001-10-01
The solid solutions of Sn1–TiO2 (0.0 < < 0.25) were prepared by the usual high temperature ceramic processing techniques with small amounts of dopants such as Nb, Co, Al. The electrical measurements (log –log ) on the ohmically metal electroded sintered pellets showed the non-linear behaviour. The nonlinear coefficient was found to decrease from 12 to 3 with increase in . On the other hand, the breakdown voltage (b) showed the increase with the increase in . This complex electrical behaviour is explained on the effects of the three dopants (as varistor former, performance enhancer and highlighter) on the microstructural features of the dense pellet.
Institute of Scientific and Technical Information of China (English)
汤鱼; 常山; 王志强; 宿吉鹏
2011-01-01
The translational - rotational - coupling dynamic model has been founded of herringbone tooth planetary transmission for analyzing the influence of gear mesh stiflhess and bearing stiffness to vibration characteristics of planetary transmission system. In the dynamic model, the proposed model admits three degrees - of- freedom for each component and includes the key factors affecting planetary gears vibration such as component bearing stiffness, time -varying mesh stiffness and so on. The dynamic differential equation is obtained base on system kinematics equation and solve the eigenvalue question of it. The vibration characteristics can be obtained of transmission system.%为了分析齿轮啮合刚度、支承刚度对行星传动系统振动特性的影响,建立了基于人字齿行星传动的平移一扭转耦合的动力学模型.在动力学模型中,每个运动构件假定有3个自由度,同时考虑各构件的支承刚度、轮齿时变啮合刚度等影响因素.根据各构件的运动方程建立传动系统的动力学微分方程,并对其进行特征值问题求解,获取行星传动系统振动特性.
Institute of Scientific and Technical Information of China (English)
张汉园; 曹风华; 王斌
2016-01-01
目的：探讨免疫透射比浊法测定脂蛋白（a ）中，采用2种多点非线性校准方法的测定结果，并确定最合适的校准曲线。方法分别采用Y＝aX2＋bX＋c和Spline2种方法在AU680生化仪上进行脂蛋白（a）校准。分别检测200例来自临床患者的血清标本和4个标准定值血清，200例临床患者血清按照测定值高低分为5个不同梯度水平，分别统计2组数据的均值（ x ）、标准差（s），相关系数（r），相对误差（v），偏倚（％）。采用SPSS19．0软件对2组数据偏倚进行统计学分析，以 P＜0．05表示差异有统计学意义。结果200例临床患者数据表明，采用Y＝a X2＋b X＋c曲线时，0～100、＞400～600、＞600～800 mg／L组的脂蛋白（a）测定值比Spline曲线所得数值高；＞100～200 mg／L组和＞200～400 mg／L组的脂蛋白（a）测定值相反，Spline曲线所得数值较高。4个标准定值血清的测定结果，Spline曲线所得测定值更接近靶值；而Y ＝ a X2＋ b X＋c曲线所测定结果中，＞100～200 mg／L组和＞300～400 mg／L组所得值偏低，＞600～800 mg／L组所得值偏高，这与临床患者的血清标本结果一致。结论 Spline曲线更为客观，能更准确地体现免疫透射比浊法测定脂蛋白（a）整个反应过程。%Objective To adopt the results detected by the two kinds of multipoint nonlinear calibration method in immune transmission turbidimetry for detecting lipoprotein(a) and to ascertain the most suitable calibration curve .Methods The two kinds of method Y=aX2 + bX+ c and Spline were adopted to conduct the lipoprotein (a) calibration in the AU680 biochemical instru‐ment .Two hundreds serum samples from clinical patients and 4 standard fixed value serum specimens were detected respectively . The sera from 200 cases of clinical patients were divided into 5 different gradient levels .The mean value(x) ,standard deviation
VIDEO TRANSMISSION SYSTEM IN ITV APPLICATION
Institute of Scientific and Technical Information of China (English)
WangYancai; WangQunwei; WangZhaohui
1996-01-01
The transmission characteristics of video transmission mediums,coaxial cable and optical fiber ,are discussed in the paper. The formulas for frequency bandwidthare given to evaluate the video transmission distance. For typical video transmissionsystems with BB/IM and PFM/IM using optical fiber as the channel, expressions andcalculating results for both SIN and sensitivity are given. Finally. the principle for selecting different type of transmission systems according to transmission distances of the industrial TV is presented.
Energy Technology Data Exchange (ETDEWEB)
Turchetti, G. (Bologna Univ. (Italy). Dipt. di Fisica)
1989-01-01
Research in nonlinear dynamics is rapidly expanding and its range of applications is extending beyond the traditional areas of science where it was first developed. Indeed while linear analysis and modelling, which has been very successful in mathematical physics and engineering, has become a mature science, many elementary phenomena of intrinsic nonlinear nature were recently experimentally detected and investigated, suggesting new theoretical work. Complex systems, as turbulent fluids, were known to be governed by intrinsically nonlinear laws since a long time ago, but received purely phenomenological descriptions. The pioneering works of Boltzmann and Poincare, probably because of their intrinsic difficulty, did not have a revolutionary impact at their time; it is only very recently that their message is reaching a significant number of mathematicians and physicists. Certainly the development of computers and computer graphics played an important role in developing geometric intuition of complex phenomena through simple numerical experiments, while a new mathematical framework to understand them was being developed.
Rahman, Mokhlasur; Huys, Geert; Rahman, Motiur; Albert, M. John; Kühn, Inger; Möllby, Roland
2006-01-01
The persistence and transmission of Aeromonas in a duckweed aquaculture-based hospital sewage water treatment plant in Bangladesh was studied. A total of 670 samples from different sites of the hospital sewage water treatment plant, from feces of hospitalized children suffering from diarrhea, from environmental control ponds, and from feces of healthy humans were collected over a period of three years. In total, 1,315 presumptive Aeromonas isolates were biochemically typed by the PhenePlate r...
Sasikala, V.; Sajan, D.; Joseph, Lynnette; Balaji, J.; Prabu, S.; Srinivasan, P.
2017-04-01
Single crystals of (E)-N‧-(4-chlorobenzylidene)-4-methylbenzenesulfonohydrazide (CBMBSH) have been grown by slow evaporation crystal growth method. The structure stabilizing intramolecular donor-acceptor interactions and the presence of the Nsbnd H⋯O, Csbnd H⋯O and Csbnd H⋯C(π) hydrogen bonds in the crystal were confirmed by vibrational spectroscopic and DFT methods. The linear optical absorption characteristics of the solvent phase of CBMBSH were investigated using UV-Vis-NIR spectroscopic and TD-DFT approaches. The 2PA assisted RSA nonlinear absorption and the optical limiting properties of CBMBSH were studied using the open-aperture Z-scan method. The topological characteristics of the electron density have been determined using the quantum theory of atoms in molecules method.
Chiel, Elad; Kelly, Suzanne E; Harris, Alexandre M; Gebiola, Marco; Li, Xianchun; Zchori-Fein, Einat; Hunter, Martha S
2014-04-01
Wolbachia is a common intracellular bacterial endosymbiont of insects, causing a variety of effects including reproductive manipulations such as cytoplasmic incompatibility (CI). In this study, we characterized Wolbachia in the whitefly Bemisia tabaci and in the whitefly parasitoid Eretmocerus sp. nr. emiratus. We also tested for horizontal transmission of Wolbachia between and within trophic levels, and we determined the phenotype of Wolbachia in E. sp. nr. emiratus. Using multilocus sequence typing and phylogenetic analyses, we found that B. tabaci and E. sp. nr. emiratus each harbor a different and unique strain of Wolbachia. Both strains belong to the phylogenetic supergroup B. No evidence for horizontal transmission of Wolbachia between and within trophic levels was found in our study system. Finally, crossing results were consistent with a CI phenotype; when Wolbachia-infected E. sp. nr. emiratus males mate with uninfected females, wasp progeny survival dropped significantly, and the number of females was halved. This is the first description of CI caused by Wolbachia in the economically important genus Eretmocerus. Our study underscores the expectation that horizontal transmission events occur rarely in the dynamics of secondary symbionts such as Wolbachia, and highlights the importance of understanding the effects of symbionts on the biology of natural enemies.
Institute of Scientific and Technical Information of China (English)
渠珍珍; 鲍和云; 朱如鹏; 李发家
2012-01-01
针对行星齿轮传动系统,采用集中质量法建立太阳轮浮动的动力学模型,考虑时变啮合刚度和综合啮合误差的影响,推导得出系统的动力学微分方程。采用变步长Runge-Kutta数值积分方法求解动力学微分方程。对比研究了高重合度行星齿轮传动系统和普通行星齿轮传动系统的动态时域响应,动载特性和均载特性。分析结果表明：高重合度行星齿轮传动振动幅值较低,动载荷较小,均载特性较好,因此传动更加平稳,噪声减小,传动性能更好。%By using lumped-mass method, the dynamic model of planetary gear transmission with floating sun-gear was established; the time-variant stiffness and meshing error were considered in the model. The motion differential equation of the model was presented and solved by Runge-Kutta numerical integration method with variable steps. Dynamic time-domain responses, dynamic loads and load sharing characteristics of the high contact ratio planetary gear transmission and general planetary gear transmission were both investigated for comparison. The results indica- ted that the high contact ratio planetary gear transmission had lower vibration amplitude, smaller dynamic load and dynamic load-sharing coefficient. So the high contact ratio planetary gear drive had better performance with smoot- her transmission, lower noise, and its load distribution is more uniform.
Institute of Scientific and Technical Information of China (English)
杨金福; 陈策; 刘玉晗; 韩东江
2011-01-01
Based on gas-dynamic bearings and frequency coupled modulation of rotor-bearing system,the characteristics of rotor bearing system＇s nonlinear vibration experimental investigations were applied to high-speed air cycle refrigerator.Furthermore,some nonlinear characteristics,for example,the motion of rotor,bearings instability and rub-impact which always happen on the flexible shaft,were analyzed.The results show that,if the design margin of safe speed is guaranteed,the steady running speed of the rotor-bearings system can be effectively increased from 40 000 r/min to 60 000 r/min above.%基于气动轴承与轴系耦合调频技术,对高速压气机涡轮转子结构的空气循环制冷机轴系进行非线性振动性能的试验研究,进一步分析了柔性轴系存在转子运动、轴承失稳及碰摩故障的一些非线性特征.研究结果表明：在保证转速设计裕度的前提下,工作转速由40 000r/m提高到了60 000r/m.
Institute of Scientific and Technical Information of China (English)
刘乐
2015-01-01
互联网的广泛应用，使网络正在成为人类信息传播的主要渠道，尤其是电子商务的逐步发展使网络信息传播的优势更加明显。网络信息传播是集人际传播、组织传播和大众传播于一体的信息传播模式，借助先进的信息技术，网络信息传播打破了时间和空间的限制，具备便捷、高效的特点。对于电子商务发展来说，网络信息是一种重要的资源，而网络信息透过层层传播才能更好地发挥它的作用。研究表明，消费者的网络信息再传播意愿是受消费者性格特征影响的，不同性格特征的消费者在人际交往的差异会对其传播动机产生影响，最终会影响到再传播意愿。%Based on the wide application of the Internet, network information transmission is becoming the main channel of human information transmission, especially when the gradual development of the electronic commerce makes the advantage of network information transmission more apparent. The network information transmission is connected by the interpersonal communication, organization spread and mass media in the integration of information transmission mode. By means of the advanced information technology, the network information transmission is provided with the characteristic of dissemination, velocity and high efficiency. For the electronic commerce development, the network information is a kind of important resources, and is spread through layer upon layer which can better play its role. The spread motivation of network information is affected by the consumers’ characteristics. The discrepancy of interpersonal communication is to have effect on the spread motivation ultimately.
Nanofiber Fabry-Perot microresonator for nonlinear optics and cavity quantum electrodynamics.
Wuttke, C; Becker, M; Brückner, S; Rothhardt, M; Rauschenbeutel, A
2012-06-01
We experimentally realize a Fabry-Perot-type optical microresonator near the cesium D2 line wavelength based on a tapered optical fiber, equipped with two fiber Bragg gratings that enclose a subwavelength diameter waist. Owing to the very low taper losses, the finesse of the resonator reaches F=86 while the on-resonance transmission is T=11%. The characteristics of our resonator fulfill the requirements of nonlinear optics and cavity quantum electrodynamics in the strong coupling regime. These characteristics, combined with the demonstrated ease of use and advantageous mode geometry, open a realm of applications.
Transmission positron microscopes
Energy Technology Data Exchange (ETDEWEB)
Doyama, Masao [Teikyo University of Science and Technology, Uenohara, Yamanashi 409-0193 (Japan)]. E-mail: doyama@ntu.ac.jp; Kogure, Yoshiaki [Teikyo University of Science and Technology, Uenohara, Yamanashi 409-0193 (Japan); Inoue, Miyoshi [Teikyo University of Science and Technology, Uenohara, Yamanashi 409-0193 (Japan); Kurihara, Toshikazu [Institute of Materials Structure Science (IMSS), High Energy Accelerator, Research Organization (KEK), Ohno 1-1, Tsukuba, Ibaraki 305-0801 (Japan); Yoshiie, Toshimasa [Reactor Research Institute, Kyoto University, Noda, Kumatori, Osaka 590-0451 (Japan); Oshima, Ryuichiro [Research Institute for Advanced Science and Technology, Osaka Prefecture University (Japan); Matsuya, Miyuki [Electron Optics Laboratory (JEOL) Ltd., Musashino 3-1-2, Akishima 196-0021 (Japan)
2006-02-28
Immediate and near-future plans for transmission positron microscopes being built at KEK, Tsukuba, Japan, are described. The characteristic feature of this project is remolding a commercial electron microscope to a positron microscope. A point source of electrons kept at a negative high voltage is changed to a point source of positrons kept at a high positive voltage. Positional resolution of transmission microscopes should be theoretically the same as electron microscopes. Positron microscopes utilizing trapping of positrons have always positional ambiguity due to the diffusion of positrons.
Institute of Scientific and Technical Information of China (English)
ZHOU Shihua; SONG Guiqiu; REN Zhaohui; WEN Bangchun
2016-01-01
Extensive studies on nonlinear dynamics of gear systems with internal excitation or external excitation respectively have been carried out. However, the nonlinear characteristics of gear systems under combined internal and external excitations are scarcely investigated. An eight-degree-of-freedom(8-DOF) nonlinear spur gear-rotor-bearing model, which contains backlash, transmission error, eccentricity, gravity and input/output torque, is established, and the coupled lateral-torsional vibration characteristics are studied. Based on the equations of motion, the coupled spur gear-rotor-bearing system(SGRBS) is investigated using the Runge-Kutta numerical method, and the effects of rotational speed, error fluctuation and load fluctuation on the dynamic responses are explored. The results show that a diverse range of nonlinear dynamic characteristics such as periodic motion, quasi-periodic motion, chaotic behaviors and impacts exhibited in the system are strongly attributed to the interaction between internal and external excitations. Significantly, the changing rotational speed could effectively control the vibration of the system. Vibration level increases with the increasing error fluctuation. Whereas the load fluctuation has an influence on the nonlinear dynamic characteristics and the increasing excitation force amplitude makes the vibration amplitude increase, the chaotic motion may be restricted. The proposed model and numerical results can be used for diagnosis of faults and vibration control of practical SGRBS.
Zhou, Shihua; Song, Guiqiu; Ren, Zhaohui; Wen, Bangchun
2016-03-01
Extensive studies on nonlinear dynamics of gear systems with internal excitation or external excitation respectively have been carried out. However, the nonlinear characteristics of gear systems under combined internal and external excitations are scarcely investigated. An eight-degree-of-freedom(8-DOF) nonlinear spur gear-rotor-bearing model, which contains backlash, transmission error, eccentricity, gravity and input/output torque, is established, and the coupled lateral-torsional vibration characteristics are studied. Based on the equations of motion, the coupled spur gear-rotor-bearing system(SGRBS) is investigated using the Runge-Kutta numerical method, and the effects of rotational speed, error fluctuation and load fluctuation on the dynamic responses are explored. The results show that a diverse range of nonlinear dynamic characteristics such as periodic motion, quasi-periodic motion, chaotic behaviors and impacts exhibited in the system are strongly attributed to the interaction between internal and external excitations. Significantly, the changing rotational speed could effectively control the vibration of the system. Vibration level increases with the increasing error fluctuation. Whereas the load fluctuation has an influence on the nonlinear dynamic characteristics and the increasing excitation force amplitude makes the vibration amplitude increase, the chaotic motion may be restricted. The proposed model and numerical results can be used for diagnosis of faults and vibration control of practical SGRBS.
DEFF Research Database (Denmark)
Andersen, J.S.; Bedaux, J.J.M.; Kooijman, S.A.L.M.;
2000-01-01
This paper describes the influence of design characteristics on the statistical inference for an ecotoxicological hazard-based model using simulated survival data. The design characteristics of interest are the number and spacing of observations (counts) in time, the number and spacing of exposure...
Seider, Warren D.; Ungar, Lyle H.
1987-01-01
Describes a course in nonlinear mathematics courses offered at the University of Pennsylvania which provides an opportunity for students to examine the complex solution spaces that chemical engineers encounter. Topics include modeling many chemical processes, especially those involving reaction and diffusion, auto catalytic reactions, phase…
Indian Academy of Sciences (India)
Guha Dharmarajan
2015-03-01
Inbreeding in parasite populations can have important epidemiological and evolutionary implications. However, theoretical models have predominantly focussed on the evolution of parasite populations under strong selection or in epidemic situations, and our understanding of neutral gene dynamics in parasite populations at equilibrium has been limited to verbal arguments or conceptual models. This study focusses on how host–parasite population dynamics affects observed levels of inbreeding in a random sample of parasites from an infinite population of hosts by bridging traditional genetic and parasitological processes utilizing a backward–forward branching Markov process embedded within a flexible statistical framework, the logarithmic-poisson mixture model. My results indicate that levels of inbreeding in parasites are impacted by demographic and/or transmission dynamics (subdivided mating, aggregated transmission dynamics and host spatial structure), and that this inbreeding is poorly estimated by ‘equilibrium’ levels of inbreeding calculated assuming regular systems of mating. Specifically, the model reveals that at low levels of inbreeding ( ≤ 0.1), equilibrium levels of inbreeding are lower than those observed, while at high levels of inbreeding the opposite pattern occurs. The model also indicates that inbreeding could have important epidemiological implications (e.g., the spread of recessive drug resistance genes) by directly impacting the observed frequency of rare homozygotes in parasite populations. My results indicate that frequencies of rare homozygotes are affected by aggregated transmission dynamics and host spatial structure, and also that an increase in the frequency of rare homozygotes can be caused by a decrease in effective population size solely due to the presence of a subdivided breeding system.
Nonlinear optical properties of ultrathin metal layers
DEFF Research Database (Denmark)
Lysenko, Oleg
2016-01-01
. The optical characterization of the plasmonic waveguides is performed using femtosecond and picosecond optical pulses. Two nonlinear optical effects in the strip plasmonic waveguides are experimentally observed and reported. The first effect is the nonlinear power transmission of the plasmonic mode......-order nonlinear susceptibility of the plasmonic mode in the gold strip waveguides significantly depends on the metal layer thickness and laser pulse duration. This dependence is explained in detail in terms of the free-electron temporal dynamics in gold. The third-order nonlinear susceptibility of the gold layer...... duration dependence of the third-order nonlinear susceptibility of gold is calculated in the broad range from tens of femtoseconds to tens of picoseconds using the two-temperature model of the free-electron temporal dynamics of gold, and shows the saturation of the thirdorder nonlinear susceptibility...
Nonlinear mathematical modeling and sensitivity analysis of hydraulic drive unit
Kong, Xiangdong; Yu, Bin; Quan, Lingxiao; Ba, Kaixian; Wu, Liujie
2015-09-01
The previous sensitivity analysis researches are not accurate enough and also have the limited reference value, because those mathematical models are relatively simple and the change of the load and the initial displacement changes of the piston are ignored, even experiment verification is not conducted. Therefore, in view of deficiencies above, a nonlinear mathematical model is established in this paper, including dynamic characteristics of servo valve, nonlinear characteristics of pressure-flow, initial displacement of servo cylinder piston and friction nonlinearity. The transfer function block diagram is built for the hydraulic drive unit closed loop position control, as well as the state equations. Through deriving the time-varying coefficient items matrix and time-varying free items matrix of sensitivity equations respectively, the expression of sensitivity equations based on the nonlinear mathematical model are obtained. According to structure parameters of hydraulic drive unit, working parameters, fluid transmission characteristics and measured friction-velocity curves, the simulation analysis of hydraulic drive unit is completed on the MATLAB/Simulink simulation platform with the displacement step 2 mm, 5 mm and 10 mm, respectively. The simulation results indicate that the developed nonlinear mathematical model is sufficient by comparing the characteristic curves of experimental step response and simulation step response under different constant load. Then, the sensitivity function time-history curves of seventeen parameters are obtained, basing on each state vector time-history curve of step response characteristic. The maximum value of displacement variation percentage and the sum of displacement variation absolute values in the sampling time are both taken as sensitivity indexes. The sensitivity indexes values above are calculated and shown visually in histograms under different working conditions, and change rules are analyzed. Then the sensitivity
Institute of Scientific and Technical Information of China (English)
郑洪全; 宁海春
2016-01-01
In order to reduce the transmission loss, strengthen the medium loaded plasma waveguide mode field constraint and optimize the plasma waveguide transmission performance, a further research on waveguide transmission characteristics of the dielectric loaded surface plasmon was studied. A waveguide with spine type medium load plasma was designed and the relationship between the geometric parameters and the geometrical parameters of the waveguide in the mode field distribution and its transmission parameters were studied. The simulation results show that the electric field component of the base mode is mainly distributed in the metal/dielectric layer 1 interface. As a result, the transmission characteristic of the model changes with the variations of the geometrical parameters of waveguide. Hence, the field can be effectively controlled by shifting the geometrical parameters of the waveguide and localization can be enhanced obviously.%为降低传输过程中的损耗，加强介质加载等离子体波导的模式场约束，并且优化等离子体波导的传输性能，对基于介质加载的表面等离子体波导的传输特性做了进一步的研究，设计了一种脊背型介质加载等离子体波导，并对其模式场分布及其传输参数随波导中的几何参数与电磁参数的变化关系做了相应的研究。仿真结果得出：基模的电场分量主要分布在该结构的金属/介质层1界面。该模式的传输特性，随着该波导的几何参数的变化而发生相应改变，因而可以通过改变这种结构的几何参数，对场实现有效控制，使其局域性明显增强。
Institute of Scientific and Technical Information of China (English)
蒙成举; 戚朝伟; 杨德贵
2015-01-01
The transmission characteristics of 1D symmetrical photonic crystal with nematic liquid crystal ( LC) defect is studied by using temperature characteristics of the thermo optic effect of LC and transfer matrix method.The results show that without LC defect in the photonic crystal, the one defect mode with a transmission rate of 100%appears in the relatively wide forbidden band range; while LC defect is introduced in the photonic crystal, the transmission rate of band edge drops sharply and the two defect modes ( the transmission rate is 100%) appear in the band gap at same time.The position of LC defect mode moves to short wavelength with the increased temperature of LC, and it moves to longer wavelength by increasing the thickness of LC, but there is no change to the vacancy defect mode as the temperature or thickness of LC increases.These modulation effects of LC materials on transmission spectrum of photonic crystal can provide positive guidance for the design of tunable photonic crystal optical devices.%利用液晶热光效应的温度特性，并通过传输矩阵法理论，研究了液晶缺陷一维光子晶体的光传输特性。结果表明，当无液晶缺陷时，在较宽的禁带范围出现一条缺陷模，当在光子晶体中引入液晶缺陷时，禁带边缘通带的透射率大幅下降，同时禁带中增加了一条液晶缺陷模，形成双缺陷模特征，且透射率均为100％；随着液晶材料温度的增大，液晶缺陷模的位置向短波方向移动，而随着液晶层厚度的变化其位置向长波方向移动，但右边空位缺陷模的位置并未受到液晶温度和厚度的影响。液晶材料对光子晶体透射谱的这种调制作用，为设计可调谐光子晶体光学器件提供指导意义。
... Abroad Treatment Basic Statistics Get Tested Find an HIV testing site near you. Enter ZIP code or city Follow HIV/AIDS CDC HIV CDC HIV/AIDS See RSS | ... on HIV Syndicated Content Website Feedback HIV/AIDS HIV Transmission Language: English (US) EspaÃ±ol (Spanish) Recommend ...
Institute of Scientific and Technical Information of China (English)
何畅然; 贺敬良; 何渠
2015-01-01
基于多体动力学理论，分析了箱体受载后产生的柔性变形对变速箱动态特性的影响。首先，通过提取箱体刚度矩阵、质量矩阵和节点位置信息，并将其与传动部件虚拟装配，建立了变速箱动态分析模型。其次，依据弹性力学理论，对因箱体柔性变形并考虑其它零部件受载变形导致的齿轮副啮合错位、传递误差、动态啮合力进行了量化分析。最后，针对箱体受载变形引起的变速箱动态载荷，提出了改善变速箱结构的具体措施。以上分析结果可为改善变速箱动态性能提供借鉴。%Based on the theory of multi body dynamics, the dynamic characteristic of transmission was ana-lyzed in this paper when the box was flexibly deformed under load. First, the stiffness matrix、mass matrix and node positions of transmission box were extracted and combined with driving part to assemble virtually, the transmission dynamic analysis model was built. Then, the misalignment、transmission error、dynamic mesh forces of the meshing gear pair due to the deformation under load on box and other parts were numeri-cally analyzed, which is based on the elastic-mechanics theory. Finally, in view of the transmission dynamic load resulted from the box deformation under load, the method was proposed to improve the box structure. All above analysis results provide references for improving the dynamic performance of transmission.
Transmissions in vehicles 2010
Energy Technology Data Exchange (ETDEWEB)
NONE
2010-07-01
) Electromechanically actuated double clutch and EV transmissions (S. Rietentiet); (36) Linear actuation as a future choice to reduce costs and improve transmission efficiency (J. Behrenroth); (37) Forward-looking solutions for transmissions in electric vehicles - Transmission concepts for electric vehicle/potentials from system and component perspective (M.J. Derse); (38) Rotor position sensor for hybrid drives and electric drives - New generation eddy current position sensor (R. Moeller); (39) Electric axle drive with torque-vectoring-functionality (B.-R. Hoehn); (40) Extreme shift times and high comfort with the DCT are not a contradiction. - The function development and application of the DCT in the Mercedes-BenzSLS AMG (M. Hart); (41) The next generation of GETRAG PowerShift {sup registered} transmissions for FWD applications (S. Bungart); (42) Modular dual clutch transmission as all-wheel drivevariant for a sports car in the tip performance class (M. Fischer); (43) Potential of sintered friction linings in synchronizers (O. Back); (44) Friction between sliding pads and sleeve - Effects on the shifting process (T. Skubacz); (45) New developments in cold forging of hollow gear parts - Extension of the geometrical design of cold formed gear construction parts (S. Rudolf); (46) Start-up device for passenger cars based on a hydrodynamic coupling (A. Menne); (47) State and parameter estimation for the determination of clutch characteristics for wet clutches (A. Tarasow); (48) Control engineering in system development - Additional benefit thanks to control engineering using the example of active vibration damping (G. Bauer).
2015-01-01
From the Back Cover: The emphasis throughout the present volume is on the practical application of theoretical mathematical models helping to unravel the underlying mechanisms involved in processes from mathematical physics and biosciences. It has been conceived as a unique collection of abstract methods dealing especially with nonlinear partial differential equations (either stationary or evolutionary) that are applied to understand concrete processes involving some important applications re...
Single-step emulation of nonlinear fiber-optic link with gaussian mixture model
DEFF Research Database (Denmark)
Borkowski, Robert; Doberstein, Andy; Haisch, Hansjörg
2015-01-01
We use a fast and low-complexity statistical signal processing method to emulate nonlinear noise in fiber links. The proposed emulation technique stands in good agreement with the numerical NLSE simulation for 32 Gbaud DP-16QAM nonlinear transmission.......We use a fast and low-complexity statistical signal processing method to emulate nonlinear noise in fiber links. The proposed emulation technique stands in good agreement with the numerical NLSE simulation for 32 Gbaud DP-16QAM nonlinear transmission....
Programmable Nonlinear ADC Using Optimal-Sized ROM
K Dinesh; Anvekar, *; Sonde, BE
1991-01-01
A new programmable successive approximation ADC useful for realizing nonlinear transfer characteristics often required in instrumentation and communications is presented. This nonlinear ADC (NADC) requires a much smaller sized ROM than an NADC reported earlier
Analysis on the effect of nonlinear polarization evolution in nonlinear amplifying loop mirror
Institute of Scientific and Technical Information of China (English)
Feng Qu; Xiaoming Liu; Pu Zhang; Xubiao Jiang; Hongming Zhang; Minyu Yao
2005-01-01
By considering the cross phase modulation (XPM) between the two orthogonal poparization components,the nonlinear birefringence and nonlinear polarization evolution (NPE) in highly-nonlinear fiber (HNLF),as well as the unequal evolutions of the state of polarization (SOP) between the clockwise (CW) and counter-clockwise (CCW) waves in a nonlinear amplifying loop mirror (NALM) are analyzed. It is pointed out that the traditional cosine expression is no longer valid for the power transmission of NALM due to uncompleted interference under the high power condition. The analytical expression considering NPE effect is derived, and the experimental result is presented.
Nonlinear estimation and control of automotive drivetrains
Chen, Hong
2014-01-01
Nonlinear Estimation and Control of Automotive Drivetrains discusses the control problems involved in automotive drivetrains, particularly in hydraulic Automatic Transmission (AT), Dual Clutch Transmission (DCT) and Automated Manual Transmission (AMT). Challenging estimation and control problems, such as driveline torque estimation and gear shift control, are addressed by applying the latest nonlinear control theories, including constructive nonlinear control (Backstepping, Input-to-State Stable) and Model Predictive Control (MPC). The estimation and control performance is improved while the calibration effort is reduced significantly. The book presents many detailed examples of design processes and thus enables the readers to understand how to successfully combine purely theoretical methodologies with actual applications in vehicles. The book is intended for researchers, PhD students, control engineers and automotive engineers. Hong Chen is a professor at the State Key Laboratory of Automotive Simulation and...
Controller Design of Complex System Based on Nonlinear Strength
Directory of Open Access Journals (Sweden)
Rongjun Mu
2015-01-01
Full Text Available This paper presents a new idea of controller design for complex systems. The nonlinearity index method was first developed for error propagation of nonlinear system. The nonlinearity indices access the boundary between the strong and the weak nonlinearities of the system model. The algorithm of nonlinearity index according to engineering application is first proposed in this paper. Applying this method on nonlinear systems is an effective way to measure the nonlinear strength of dynamics model over the full flight envelope. The nonlinearity indices access the boundary between the strong and the weak nonlinearities of system model. According to the different nonlinear strength of dynamical model, the control system is designed. The simulation time of dynamical complex system is selected by the maximum value of dynamic nonlinearity indices. Take a missile as example; dynamical system and control characteristic of missile are simulated. The simulation results show that the method is correct and appropriate.
Jong, A.N. de; Eijk, A.M.J. van; Fritz, P.J.; Cohen, L.H.; Moerman, M.M.
2007-01-01
The knowledge of the atmospheric aerosol characteristics is of great importance for the range performance of Infrared and Electro-Optical sensor systems. The composition, the concentration and the size distribution of aerosols determine their scattering behavior as function of wavelength and thus th
Jong, A.N. de; Eijk, A.M.J. van; Fritz, P.J.; Cohen, L.H.; Moerman, M.M.
2007-01-01
The knowledge of the atmospheric aerosol characteristics is of great importance for the range performance of Infrared and Electro-Optical sensor systems. The composition, the concentration and the size distribution of aerosols determine their scattering behavior as function of wavelength and thus
Institute of Scientific and Technical Information of China (English)
艾超; 叶壮壮; 孔祥东; 廖利辉
2015-01-01
Fixed displacement pump-variable displacement motor is the main drive system of hy-draulic type wind turbine,the system is controlled by a variable displacement mechanism after grid-connected.To study the pressure control characteristics,a mathematical model was built and the trans-fer function describing the pressure to the position of the motor swash plate was derived.Compared with the identified model obtained from data identification in MATLAB system,the built model was verified,which laid theoretical and test foundation for further maximum power point tracking(MPPT) based on pressure control in hydraulic type wind turbine.%液压型风力发电机组主传动系统为定量泵变量马达闭式系统，风机并网后依靠变量马达变排量机构对系统进行控制。研究了系统压力控制特性，建立了并网后主传动系统数学模型，得出了系统压力对马达斜盘摆角的传递函数。利用 MATLAB 辨识工具箱，根据实验数据，对系统压力控制模型进行数据辨识，并与理论模型进行对比，验证了理论模型的准确性，为液压型风力发电机组通过压力控制实现最佳功率追踪控制奠定理论与实验基础。
Enhanced nonlinear optical response of one-dimensional metal-dielectric photonic crystals.
Lepeshkin, Nick N; Schweinsberg, Aaron; Piredda, Giovanni; Bennink, Ryan S; Boyd, Robert W
2004-09-17
We describe a new type of artificial nonlinear optical material composed of a one-dimensional metal-dielectric photonic crystal. Because of the resonant nature of multiple Bragg reflections, the transmission within the transmission band can be quite large, even though the transmission through the same total thickness of bulk metal would be very small. This procedure allows light to penetrate into the highly nonlinear metallic layers, leading to a large nonlinear optical response. We present experimental results for a Cu/SiO(2) crystal which displays a strongly enhanced nonlinear optical response (up to 12X) in transmission.
Harmonic Phase Response of Nonlinear Radar Targets
2015-10-01
to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT...of an improvised explosive device (IED). Previous nonlinear radar systems detect targets via transmission of a single frequency ω, stepping...electronically nonlinear components, such as transistors, diodes , and semiconductors. While many circuit devices, such as amplifiers, mixers, and
Blank, V.; Thomson, M. D.; Roskos, H. G.
2013-07-01
We present a characterization of the combined spatial and spectral properties of the terahertz (THz) and mid-infrared emission from gas plasmas generated and driven by two-colour femtosecond optical pulses. For its use in nonlinear spectroscopy, the impact of the relatively complex spatial profile for both broadband (∼ 10 THz) and ultra-broadband (> 100 THz) emission needs to be considered, in particular for experiments based on z-scan techniques. Here we apply spatially resolved measurements based on both field autocorrelation and sum-frequency (up-conversion) detection. Based on these results, we present simulations of the ultra-broadband profile during its passage through a focal region. In addition to the inherent features of the emission profile due to the generation mechanism in the plasma filament, we also analyse the role of the semconductor (silicon) wafer typically placed after the plasma to discard the optical pump beams, whose photoexcitation also can play a role in the resultant THz profile.
Transmitting information by controlling nonlinear oscillators
Tôrres, Leonardo A. B.; Aguirre, Luis A.
2004-09-01
The transmission of information relying on the perturbation of nonlinear oscillators vector fields can be approached in a unified manner. This can be accomplished by making use of the Information Transmission Via Control principle, which is stated and proved in the present work. In short, this principle establishes that any controller used to identically synchronize pairs of nonlinear oscillators, including chaotic ones as a special case, can be actually employed as demodulator/decoder in the process of information recovery. Other theoretical results related to the practical realization of the ITVC principle are presented and experimental data is provided showing a good agreement with the proposed theory.
Simulation Research on Hydraulic Mount Nonlinear Dynamic Characteristics%液压悬置非线性动态特性仿真研究
Institute of Scientific and Technical Information of China (English)
时培成; 陈无畏; 姜武华
2009-01-01
针对液压悬置复杂的动态特性,运用流体动力学理论及液压原理,建立了某轿车动力总成液压悬置的非线性数学模型,提出了模拟液压悬置动态特性的一种数值分析方法,并对目标液压悬置的动态特性进行了多工况仿真实验对比.研究结果表明所建模型是正确的、实用的,而且其通用性较强,能为下一步更精确的汽车动力总成悬置系统匹配选型、优化分析、隔振特性研究提供基础.%Aimed at the complicated dynamic characteristics of hydraulic mount, an automobile powertrain hydraulic mount's non - linear mathematics model was created with the hydrodynamics theory and hydraulic principle. A numerical analysis method for simulating the dynamic characteristics of hydraulic mount was put out, and the characteristics was studied by contrasting simulations and experiments under a few working conditions. The results show the model is correct, practical and universal, which can provide a foundation for more precise automobile powertrain mount system matching, optimizing analysis and vibration isolating research.
Institute of Scientific and Technical Information of China (English)
高保生; 朱良彬
2011-01-01
无人机地空链路数据传输存在多径衰落的影响。详细分析了无人机在滑行、起降和巡航3种状态下地空信道的传输特性。针对滑行、起降阶段多径时延大、存在频率选择性衰落的问题,提出了宽带数据传输技术——单载波频域均衡（SC-FDE）和正交频分复用（OFDM）,并对SC-FDE进行了性能仿真。仿真结果表明,SC-FDE可以有效解决无人机滑行、起降阶段的多径衰落影响,提高宽带数据传输质量。%The multipath fading exists during the Ground-to-air data transmission of UAV.This paper analyzes the characteristics of the ground-to-air communication at taxiing scenario,arrival and takeoff scenario and en-route scenario.Aiming at the multipath fading caused serious frequency selective fading at taxiing scenario,arrival and takeoff scenario,broadband transmission scheme is given,such as SC-FDE and OFDM.The analysis and simulation results of SC-FDE demonstrate that it can eliminate the multipath fading influence at the taxiing scenario,arrival and takeoff scenario of the UAV system and the data transmission performance is improved.
Saturation at low x and nonlinear evolution
Stasto, A. M.
2002-01-01
In this talk the results of the analytical and numerical analysis of the nonlinear Balitsky-Kovchegov equation are presented. The characteristic BFKL diffusion into infrared regime is suppressed by the generation of the saturation scale. We identify the scaling and linear regimes for the solution. We also study the impact of subleading corrections onto the nonlinear evolution.
Institute of Scientific and Technical Information of China (English)
曹旭佳
2015-01-01
1000 kV 交流特高压输电线路是解决我国电力能源分布不均匀，降低电力负荷的有效手段。1000 kV 交流特高压线路的维护工作也开始受到社会各界的广泛关注。为了保障交流特高压线路能够安全运行，文章分析了1000 kV 交流特高压输电线路运行特性，借鉴了国外先进经验，总结了其中的关键技术。%1 000 kV AC UHV transmission line is an effective means of uneven distribution of electric energy,reduce the power load solutions,the maintenance work of 1 000 kV AC UHV line has begun to attract widespread concern in the community,in order to protect AC UHV safe operation,we must summarize the key technologies,learn from foreign ad-vanced experience,this paper analyzes the operating characteristics of 1 000 kV UHV AC transmission lines.
Kim, Hyun Sung; Pham, Tung Cao Thanh; Yoon, Kyung Byung
2012-05-16
The demand for nonlinear optical (NLO) materials with exceptional NLO properties is very large, and hence the search for such materials should be continued not only to enhance their functions in current applications but also to help expedite the materialization of photonics in which photons instead of electrons are used for signal processing, transmission, and storage. This article summarizes the preparation, characteristics, and the future perspectives of novel second order nonlinear optical (2NLO) materials prepared by orientation-controlled incorporation of 2NLO molecules into zeolite channels and third order nonlinear optical (3NLO) materials prepared by compartmentalization of very small (<1.3 nm) PbS QDs within zeolite nanopores under different environments, and the novel chemistry newly unveiled during the preparation of novel zeolite based NLO materials. This journal is © The Royal Society of Chemistry 2012
Quantum well nonlinear microcavities
Oudar, J. L.; Kuszelewicz, R.; Sfez, B.; Pellat, D.; Azoulay, R.
We report on recent progress in reducing the power threshold of all-optical bistable quantum well vertical microcavities. Significant improvements are achieved through an increase of the cavity finesse, together with a reduction of the device active layer thickness. A critical intensity of 5 μW/μm 2 has been observed on a microcavity of finesse 250, with a nonlinear medium of only 18 GaAs quantum wells of 10 nm thickness. Further improvements of the Bragg mirror quality resulted in a finesse of 700 and a power-lifetime product of 15 fJ/μm 2. Microresonator pixellation allows to obtain 2-dimensional arrays. A thermally-induced alloy-mixing technique is described, which produced a 110 meV carrier confinement energy, together with a refractive index change of -.012, averaged over the 2.6 μm nonlinear medium thickness. The resulting electrical and optical confinement is shown to improve the nonlinear characteristics, by limiting lateral carrier diffusion and light diffraction.
Rahman, Mokhlasur; Huys, Geert; Rahman, Motiur; Albert, M. John; Kühn, Inger; Möllby, Roland
2007-01-01
The persistence and transmission of Aeromonas in a duckweed aquaculture-based hospital sewage water treatment plant in Bangladesh was studied. A total of 670 samples from different sites of the hospital sewage water treatment plant, from feces of hospitalized children suffering from diarrhea, from environmental control ponds, and from feces of healthy humans were collected over a period of three years. In total, 1,315 presumptive Aeromonas isolates were biochemically typed by the PhenePlate rapid screening system (PhP-AE). A selection of 90 representative isolates was further analyzed with PhenePlate (PhP) extended typing (PhP-48), fatty acid methyl ester analysis, and amplified fragment length polymorphism (AFLP) fingerprinting. In addition, the prevalence of the putative virulence factors hemolysin and cytotoxin and the presence of the cytolytic enterotoxin gene (AHCYTOEN) were analyzed. Aeromonas was found at all sites of the treatment plant, in 40% of the samples from environmental control ponds, in 8.5% of the samples from hospitalized children suffering from diarrhea, and in 3.5% of samples from healthy humans. A significantly high number of Aeromonas bacteria was found in duckweed, which indicates that duckweed may serve as a reservoir for these bacteria. PhP-AE typing allowed identification of more than 192 distinct PhP types, of which 18 major PhP types (MTs) were found in multiple sites and during several occasions. AFLP fingerprinting revealed the prevalence of genotypically indistinguishable Aeromonas isolates among certain PhP MTs recovered from different sampling occasions and/or at multiple sites. Hemolytic and cytotoxic activities were observed in 43% of the tested strains, whereas 29% possessed the cytolytic enterotoxin gene AHCYTOEN. Collectively, two specific MTs associated with diarrhea were shown to exhibit high cytotoxicity. Furthermore, all tested isolates of these major types were positive for the cytolytic enterotoxin gene. In conclusion
Luo Sheng; Huang Sai Jun; He Yu Sheng; Li Chun Guang; Zhang Xue Qiang
2003-01-01
A modified Ambegaokar-Halperin thermal-fluctuation model has been developed to describe the c-axis V-I characteristics and low-current ohmic resistance of highly anisotropic superconductors in a magnetic field parallel to the c-axis. The model assumes loss of phase coherence across the CuO-planes associated with the correlated motion of pancake vortices in the liquid state. The predicted V-I characteristics in the current-induced transition from the superconducting to the resistive state are in good agreement with measurements on a 2212-BSCCO single crystal as a function of temperature and field, provided the effect of the interlayer capacitance is taken into account. The measurements are consistent with a flux pancake correlation length within the CuO-planes varying as xi sub 0 /(T/T sub 0 - 1) supnu, where xi sub 0 = 1.57 +- 0.08 mu m and nu = 0.50 +- 0.01. Our measurements imply a current-dependent interlayer resistance above and below T sub c.
Institute of Scientific and Technical Information of China (English)
唐俊; 邓立苗; 陈辉; 栾涛; 马文杰
2014-01-01
The purpose of the study was to create database of characteristics from maize leaf transmission images, analyze the rules of characteristics variation with maize varieties and the recognition results of different types of characteristics in order to provide a basis for further research of identifying maize varieties from leaf transmission image of different growth periods based on machine vision. [Method] Twenty-one common varieties of maize were selected as the research materials. The maize leaves at jointing stage, small bell stage, large bell stage and tasselling stage were collected. A total of 420 high quality transmission images of maize leaves were taken in lamp box. The software for characteristic extraction and recognition of maize leaves was designed and developed based on Matlab R2009a, which included image preprocessing module, characteristic extraction module, neural network recognition module and threshold selection module. The transmission images of maize leaves at jointing stage, small bell stage, large bell stage and tasselling stage were pre-processed by the software. Then 48 characteristics of color group, shape group and texture group were extracted from transmission images of maize leaf, and a total of 20 160 characteristic data. In order to study the rules of characteinristics variation with maize varieties, the coefficient of variation of 48 characteristics of leaf transmission image among different maize varieties were analyzed. In order to search the important characteristics with strong ability of identifying maize varieties from transmission images of leaves, the Artificial Neural Network was built and the recognition rate of single characteristics from different time were analyzed. In order to study the recognition results, the recognition rates of the three groups of characteristics and the group combinations of characteristics from different time were further analyzed. [Result] The results in 4 stages indicated that there were
Institute of Scientific and Technical Information of China (English)
孟景辉; 谢保锋; 高利民
2011-01-01
分析不同载频的区间轨道电路检测数据散点图,提出采片用线性拟合方法分析区间轨道电路传输特性.对不同载频不同时期的区间轨道电路检测数据进行线性拟合处理,提取衰减系数、波动系数和相关系数 3个特性指标.将特性指标转化为随时变化而变化的趋势图,用以研究区间轨道电路传输特性的变化趋势,并判断补偿电容工作状态.提出基于历史数据库的区间轨道电路动态性能评判方法,该方法与现有的标准曲线对比法相比,减少了数据需要量,增加了趋势分析功能.%According to the analysis of the scatter diagram which was drawn based on the inspection data of the section track circuit with different carrier frequencies, the linear fitting method was proposed to analyze the transmission characteristics of the section track circuit. The inspection data of the section track circuit with different carrier frequencies in different periods were processed with linear fitting method to extract three characteristic indexes, namely, the attenuation coefficient, the fluctuation coefficient and the correlation coefficient. The characteristic indexes were transformed into time-varied trend chart to research the variation trend for the transmission characteristics of the section track circuit and to judge the working state of the compensation capacitors. The method based on historical database was proposed to evaluate the dynamic performance of the section track circuit. Compared with the existing standard curve contrast method, this method demands less data and adds the function of trend analysis.
Rajasekar, Shanmuganathan
2016-01-01
This introductory text presents the basic aspects and most important features of various types of resonances and anti-resonances in dynamical systems. In particular, for each resonance, it covers the theoretical concepts, illustrates them with case studies, and reviews the available information on mechanisms, characterization, numerical simulations, experimental realizations, possible quantum analogues, applications and significant advances made over the years. Resonances are one of the most fundamental phenomena exhibited by nonlinear systems and refer to specific realizations of maximum response of a system due to the ability of that system to store and transfer energy received from an external forcing source. Resonances are of particular importance in physical, engineering and biological systems - they can prove to be advantageous in many applications, while leading to instability and even disasters in others. The book is self-contained, providing the details of mathematical derivations and techniques invo...
Institute of Scientific and Technical Information of China (English)
1996-01-01
3.1 A Unified Nonlinear Feedback Functional Method for Study Both Control and Synchronization of Spatiotemporal Chaos Fang Jinqing Ali M. K. (Department of Physics, The University of Lethbridge,Lethbridge, Alberta T1K 3M4,Canada) Two fundamental questions dominate future chaos control theories.The first is the problem of controlling hyperchaos in higher dimensional systems.The second question has yet to be addressed:the problem of controlling spatiotemporal chaos in a spatiotemporal system.In recent years, control and synchronization of spatiotemporal chaos and hyperchaos have became a much more important and challenging subject. The reason for this is the control and synchronism of such behaviours have extensive and great potential of interdisciplinary applications, such as security communication, information processing, medicine and so on. However, this subject is not much known and remains an outstanding open.
Karatay, Ahmet; Aksoy, Çagla; Gul Yaglioglu, H.; Elmali, Ayhan; Kürüm, Ulaş; Ateş, Aytunç; Gasanly, Nizami
2011-07-01
We investigated the nonlinear and saturable absorption characteristics of Ga0.90In0.10Se and Ga0.85In0.15Se semiconductor crystals and their very thin amorphous films by open aperture (OA) Z-scan and pump-probe techniques. The linear absorption spectra indicated a blue shift in energy with increasing film thickness. This can be attributed to the quantum confinement effect. For both 4 ns and 65 ps pulse durations the two photon absorption coefficients of Ga0.90In0.10Se and Ga0.85In0.15Se crystals increased with increasing input intensities. The life time of the localized defect states was measured as 3 ns for both Ga0.90In0.10Se and Ga0.85In0.15Se films while it was around 10 ns for GaSe and InSe films. Open aperture Z-scan experiments with a 4 ns pulse duration did not exhibit any saturable absorption behavior for thin films since the life time of localized defect states was not long enough to saturate these films. Thinner films exhibited saturable absorption and thicker films exhibited nonlinear absorption for a 65 ps pulse duration. This behavior was attributed to increasing localized defect states with increasing film thickness. The experimental curves were fitted to the theory of the open aperture Gaussian-beam Z-scan based on the Adomian decomposition method incorporating one photon, two photon, and free carrier absorptions and their saturations. The lowest saturation intensity threshold for the Ga0.90In0.10Se film was found to be 1.38 × 102 MW cm - 2 for 43 nm film thickness.
Nonlinear structural analysis using integrated force method
Indian Academy of Sciences (India)
N R B Krishnam Raju; J Nagabhushanam
2000-08-01
Though the use of the integrated force method for linear investigations is well-recognised, no efforts were made to extend this method to nonlinear structural analysis. This paper presents the attempts to use this method for analysing nonlinear structures. General formulation of nonlinear structural analysis is given. Typically highly nonlinear bench-mark problems are considered. The characteristic matrices of the elements used in these problems are developed and later these structures are analysed. The results of the analysis are compared with the results of the displacement method. It has been demonstrated that the integrated force method is equally viable and efficient as compared to the displacement method.
Regional transmission subsystem planning
Energy Technology Data Exchange (ETDEWEB)
Costa Bortoni, Edson da [Quadrante Softwares Especializados Ltda., Itajuba, MG (Brazil); Bajay, Sergio Valdir; Barros Correia, Paulo de [Universidade Estadual de Campinas, SP (Brazil). Faculdade de Engenharia Mecanica; Santos, Afonso Henriques Moreira; Haddad, Jamil [Escola Federal de Engenharia de Itajuba, MG (Brazil)
1994-12-31
This work presents an approach for the planning of transmission systems by employing mixed--integer linear programming to obtain a cost and operating characteristics optimized system. The voltage loop equations are written in a modified form, so that, at the end of the analysis, the model behaves as a DC power flow, with the help of the two Kirchhoff`s laws, exempting the need of interaction with an external power flow program for analysis of the line loading. The model considers the occurrence of contingencies, so that the final result is a network robust to the most severe contingencies. This whole technique is adapted to the regional electric power transmission subsystems. (author) 9 refs., 4 figs.
CHARACTERIZATION AND MODELING OF SOLITON TRANSMISSION AT 2.5 GB/S OVER 200 KM
Directory of Open Access Journals (Sweden)
KHALID A. S. AL-KHATEEB
2010-09-01
Full Text Available Soliton characteristics and soliton transmission have been simulated using a VPI simulator. Simulation was also used to construct and study a soliton communication system. Near soliton pulses emitted by an actively mode-locked laser is then compressed in a dispersion-compensating fiber (DCF to produce solitons. The effects of non-linearity and active pre-chirping of mode-locked laser diode sources were also investigated. Assessment on a modeled system using real data shows that propagation over 250 km at 2.5 Gb/s in standard fibers with 20 ps pulse widths is possible in the 1550 nm wavelength range.
Ragulskis, K. M.; Yaroslavskiy, I. K.
1973-01-01
The criteria for the selection of dynamic characteristics of flexible centrifugal-inertial couplings are discussed. The basic properties considered are: (1) vibration isolation, (2) vibration quenching, and (3) transmission properties. It is stated that the most promising couplings are those with a nonlinear relation between the magnitude of the torque transmitted and the magnitude of deformation of the coupling. The efforts of various investigators are briefly analyzed. Mathematical models are developed to show the relationships of the parameters involved.
Institute of Scientific and Technical Information of China (English)
那虎; 丁正平; 孙晋峰; 杨俊清; 刘龙开; 袁芳; 洪深
2012-01-01
直流输变电系统用无源型高压直流转换开关是直流系统中的重要运行设备,其运行工况及工作特性极其特殊.笔者通过对高压直流转换开关工作原理及工况进行研究,并依据试验测得的断口电弧电流曲线的特征,对高压直流转换开关开断转换电流的电弧电流特性进行理论研究及分析,给出了电弧电流特性函数,指出高压直流转换开关开断的关键点是断口的弧阻小,变化率大,L1C1辅助支路频率高,才能开断较大的直流电流.%The passive high-voltage direct current (HVDC)circuit breaker is important for ensuring reliability of HVDC distribution system, and its working condition and characteristic are particular. In this paper, the working condition and characteristic of HVDC circuit breaker in HVDC transmission and distribution system are analyzed, the arc current characteristic of the breaker is investigated according to test data, and a function for describing arc current characteristic of the breaker is achieved. Conclusion is drawn that small arcing resistance, high varying rate, and high frequency of L1C1 circuit can facilitate breaking larger direct current by HVDC circuit breaker.
Predictive simulation of nonlinear ultrasonics
Shen, Yanfeng; Giurgiutiu, Victor
2012-04-01
Most of the nonlinear ultrasonic studies to date have been experimental, but few theoretical predictive studies exist, especially for Lamb wave ultrasonic. Compared with nonlinear bulk waves and Rayleigh waves, nonlinear Lamb waves for structural health monitoring become more challenging due to their multi-mode dispersive features. In this paper, predictive study of nonlinear Lamb waves is done with finite element simulation. A pitch-catch method is used to interrogate a plate with a "breathing crack" which opens and closes under tension and compression. Piezoelectric wafer active sensors (PWAS) used as transmitter and receiver are modeled with coupled field elements. The "breathing crack" is simulated via "element birth and death" technique. The ultrasonic waves generated by the transmitter PWAS propagate into the structure, interact with the "breathing crack", acquire nonlinear features, and are picked up by the receiver PWAS. The features of the wave packets at the receiver PWAS are studied and discussed. The received signal is processed with Fast Fourier Transform to show the higher harmonics nonlinear characteristics. A baseline free damage index is introduced to assess the presence and the severity of the crack. The paper finishes with summary, conclusions, and suggestions for future work.
Song, Qifa; Yang, Yuanbin; Lin, Wenping; Yi, Bo; Xu, Guozhang
2017-09-25
We aimed to describe the molecular epidemiological characteristics and clinical treatment outcome of typhoid fever in Ningbo, China during 2005-2014. Eighty-eight Salmonella Typhi isolates were obtained from 307 hospitalized patients. Three prevalent pulsed-field gel electrophoresis (PFGE) patterns of 54 isolates from 3 outbreaks were identified. Overall, there were 64 (72.7%) isolates from clustered cases and 24 (27.3%) isolates from sporadic cases. Resistance to nalidixic acid (NAL) (n = 47; 53.4%) and ampicillin (AMP) (n = 40; 45.4%) and rare resistance to tetracycline (TET) (n = 2; 2.3%) and gentamicin (GEN) (n = 2; 2.3%) were observed. No isolates resistant to cefotaxime (CTX), chloramphenicol (CL), ciprofloxacin (CIP), and trimethoprim-sulfamethoxazole (SXT) were found. The occurrence of reduced sensitivity to CIP was 52.3% (n = 46). The medians of fever clearance time in cases with and without complications were 7 (interquartile range (IQR): 4-10) and 5 (IQR: 3-7) days (P = 0.001), respectively, when patients were treated with CIP or levofloxacin (LEV) and/or third-generation cephalosporins (CEP). Rates of serious complications were at low levels: peritonitis (2.3%), intestinal hemorrhage (6.8%), and intestinal perforation (1.1%). The present study revealed a long-term clustering trend with respect to PFGE patterns, occasional outbreaks, and the rapid spread of AMP resistance and decreased CIP susceptibility among S. Typhi isolates in recent years.
Güth, Dirk; Erbis, Vadim; Schamoni, Markus; Maas, Jürgen
2014-04-01
High rotational speeds for brakes and clutches based on magnetorheological fluids represent a remaining challenge for the industrial or automotive application. Beside particle centrifugation effects and rotational speed-depending no-load losses, the torque characteristic is an important property that needs to considered in the design process of actuators. Due to missing experimental data for these operating conditions, in this paper the shear rate and flux depending yield stress behavior of magnetorheological uids is experimentally investigated for high rotational speeds or respectively high shear rates. Therefore a brake actuator with variable shear gap heights up to 4 mm is designed, realized and used for the experimental investigation, which are performed for a maximum shear rate of ƴ= 34; 000 s-1 under large magnetic elds. The measurement results point out a strong dependency between shear rate, magnetic ux density and resulting yield stress. For low shear gap heights, a significant reduction in the yield stress up to 10 % can be determined. Additionally the development of Taylor vortices is determined, which will not only occur in viscous case without an applied magnetic field. The measurement results are important for a reliable actuator design which should be used in application with high rotational speeds.
Pietschmann, Jana; Guinat, Claire; Beer, Martin; Pronin, Valery; Tauscher, Kerstin; Petrov, Anja; Keil, Günther; Blome, Sandra
2015-07-01
In 2007, African swine fever virus (ASFV) was introduced into the Transcaucasian countries and Russia. Since then, it has spread alarmingly and reached the European Union. ASFV strains are highly virulent and lead to almost 100% mortality under experimental conditions. However, the possibility of dose-dependent disease courses has been discussed. For this reason, a study was undertaken to assess the risk of chronic disease and the establishment of carriers upon low-dose oronasal infection of domestic pigs and European wild boar. It was demonstrated that very low doses of ASFV are sufficient to infect especially weak or runted animals by the oronasal route. Some of these animals did not show clinical signs indicative of ASF, and they developed almost no fever. However, no changes were observed in individual animal regarding the onset, course and outcome of infection as assessed by diagnostic tests. After amplification of ASFV by these animals, pen- and stablemates became infected and developed acute lethal disease with similar characteristics in all animals. Thus, we found no indication of prolonged or chronic individual courses upon low-dose infection in either species. The scattered onset of clinical signs and pathogen detection within and among groups confirms moderate contagiosity that is strongly linked with blood contact. In conclusion, the prolonged course at the "herd level" together with the exceptionally low dose that proved to be sufficient to infect a runted wild boar could be important for disease dynamics in wild-boar populations and in backyard settings.
Solitonic Information Transmission in General Relativity
Institute of Scientific and Technical Information of China (English)
SHANG Yu; WANG Gui-Dong; WU Xiao-Ning; WANG Shi-Kun; LAU Yun-Kau
2007-01-01
An exact solution of the vacuum Einstein's field equations is presented,in which there exists a congruence of null geodesics whose shear behaves like a travelling wave of the KdV equation.On the basis of this exact solution,the feasibility of solitonic information transmission by exploiting the nonlinearity intrinsic to the Einstein field equations is discussed.
Nanofiber Fabry-Perot microresonator for non-linear optics and cavity quantum electrodynamics
Wuttke, C; Brückner, S; Rothhardt, M; Rauschenbeutel, A
2012-01-01
We experimentally realize a Fabry-Perot-type optical microresonator near the cesium D2 line wavelength based on a tapered optical fiber, equipped with two fiber Bragg gratings which enclose a sub-wavelength diameter waist. Owing to the very low taper losses, the finesse of the resonator reaches F = 86 while the on-resonance transmission is T = 11 %. The characteristics of our resonator fulfill the requirements of non-linear optics and cavity quantum electrodynamics in the strong coupling regime. In combination with its demonstrated ease of use and its advantageous mode geometry, it thus opens a realm of applications.
DEFF Research Database (Denmark)
Liu, Xiang; Hu, Hao; Chandrasekhar, S.;
2014-01-01
-optical signal processing approach to generate WDM-PCTWs enables a 2-fold reduction in the needed optical transmitters as compared to the conventional approach where each idler is generated by a dedicated transmitter. Digital coherent superposition of the twin waves at the receiver enables more than doubled......We experimentally demonstrate the generation of 1.024-Tb/s Nyquist-WDM phase-conjugated vector twin waves (PCTWs), consisting of eight 128-Gb/s polarization-division-multiplexed QPSK signals and their idlers, by a broadband polarization-insensitive fiber optic parametric amplifier. This novel all...... reach in a dispersion-managed transmission link. We further study the impact of polarization-mode dispersion on the performance gain brought by the phase-conjugated twin waves, showing a gain of ∼3.8 dB in signal quality factors....
Liu, Xiang; Hu, Hao; Chandrasekhar, S; Jopson, R M; Gnauck, A H; Dinu, M; Xie, C; Winzer, P J
2014-03-24
We experimentally demonstrate the generation of 1.024-Tb/s Nyquist-WDM phase-conjugated vector twin waves (PCTWs), consisting of eight 128-Gb/s polarization-division-multiplexed QPSK signals and their idlers, by a broadband polarization-insensitive fiber optic parametric amplifier. This novel all-optical signal processing approach to generate WDM-PCTWs enables a 2-fold reduction in the needed optical transmitters as compared to the conventional approach where each idler is generated by a dedicated transmitter. Digital coherent superposition of the twin waves at the receiver enables more than doubled reach in a dispersion-managed transmission link. We further study the impact of polarization-mode dispersion on the performance gain brought by the phase-conjugated twin waves, showing a gain of ~3.8 dB in signal quality factors.
Institute of Scientific and Technical Information of China (English)
薛明富; 胡爱群
2011-01-01
虽然非线性助听器选配算法相继被提出,但对各选配算法的研究并不充分.对常用的NAL-NL1和DSL[i/o]5.0等选配算法进行了研究与仿真.首先研究了各选配算法的设计原则,并仿真分析了在各种典型听力图下,各算法所给出的声学响应特性(增益、拐点、压缩比、各频段的强调程度等),计算了客观的评价指标(响度、语音清晰度等).实验证实,NAL-NL1的原则是对语言的所有频率带整体进行响度均衡化,并且最大化语言清晰度,NAL系列算法均与此类似,而DSL[i/o]5.0的原则是响度正常化.对同样的听力图,由于设计原则与理念的不同,各算法给出了不同的响应特性,在响度和语音清晰度上也有所差异,讨论了设计原则对响应特性的影响及其对应关系.还对非线性助听器选配算法的研究现状和未来发展方向进行了一定的探讨.%Various fitting methods for non-linear hearing aids have been proposed. But the study of these fitting methods is not sufficient, and no such work has been done in China. This paper gives the study and the simulation of common fitting methods for non-linear hearing aids, such as NAL-NL1 and DSL[I/o]5.0. First, it studies the design principles of these fitting methods. Then, it simulates and analysis the acoustic response characteristics of fitting methods under various typical audiograms, such as gain, knee points, compression ratio and the degree of emphasis in different frequency bands. It calculates the objective assessment indexes like loudness and speech intelligibility. Experiments have confirmed that the principle of NAL-NL1 is to get loudness equalization among all frequency bands, and maximize the speech intelligibility. NAL series of fitting methods are similar to this while the DSL[I/o]5.0 focuses on loudness normalization. Under the same audiogram, they give different acoustic response characteristics due to the differences of design principles and
Nonlinear Materials Characterization Facility
Federal Laboratory Consortium — The Nonlinear Materials Characterization Facility conducts photophysical research and development of nonlinear materials operating in the visible spectrum to protect...
Institute of Scientific and Technical Information of China (English)
刘松山; 王庆年; 王伟华
2014-01-01
A nonlinear damping characteristic for regenerative suspension based on the torque-speed char-acteristic of regenerative motor and traditional linear damping characteristic is proposed and the influences of opening speed and the initial speed of inadequate damping interval on vibration attenuation performance are analyzed. By an-alyzing the sprung mass acceleration response of single DOF linear suspension model, the effect of initial opening speed on vibration attenuation performance is obtained. For suppressing the peak acceleration response caused by entering constant damping interval, the relative speed transfer characteristic of linear suspension model is investiga-ted, with the adjustment coefficient for initial opening speed obtained. The results of simulation show that reasonable opening speed can greatly improve the transfer characteristic of regenerative damper, while the initial speed of inad-equate damping interval has no much effect on peak response for harmonic excitation.%提出了一种基于馈能电机转矩转速特性和传统线性阻尼特性的馈能悬架非线性阻尼特性，分析开启速度和阻尼不足区初始速度对减振性能的影响。通过对传统的单自由度线性悬架模型的簧载质量加速度响应分析，得出初始开启速度对其减振性能的影响。为了抑制进入恒阻尼区后导致的加速度响应峰值，对线性模型中的相对速度传递特性的研究，得出初始开启速度的调整系数。仿真结果表明，合理的开启速度能极大地改善馈能减振器的传递特性，阻尼不足区初始速度对谐波激励时的响应峰值影响并不大。
Nonlinear cumulative damage model for multiaxial fatigue
Institute of Scientific and Technical Information of China (English)
SHANG De-guang; SUN Guo-qin; DENG Jing; YAN Chu-liang
2006-01-01
On the basis of the continuum fatigue damage theory,a nonlinear uniaxial fatigue cumulative damage model is first proposed.In order to describe multiaxial fatigue damage characteristics,a nonlinear multiaxial fatigue cumulative damage model is developed based on the critical plane approach,The proposed model can consider the multiaxial fatigue limit,mean hydrostatic pressure and the unseparated characteristic for the damage variables and loading parameters.The recurrence formula of fatigue damage model was derived under multilevel loading,which is used to predict multiaxial fatigue life.The results showed that the proposed nonlinear multiaxial fatigue cumulative damage model is better than Miner's rule.
Magnetic Force Transmission of a Reciprocating Motion
Institute of Scientific and Technical Information of China (English)
Qing-chang Tan; Fu-sheng Zheng; Jian-gang Li
2008-01-01
Magnetic force transmission of a reciprocating motion is studied by theoretical analysis and experiment. A mathematical model for calculating the magnetic force is derived using the theory of equivalent magnetic charges. An experimental rig is constructed to test the transmission and the model is verified by experiment. Effect of the transmission parameters on the magnetic force is analyzed theoretically from the model, and characteristic of the transmission is studied experimentally. Since the transmission is without direct contact between two elements, it is suitable for application in an organism.
Nonlinear singular vectors and nonlinear singular values
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
A novel concept of nonlinear singular vector and nonlinear singular value is introduced, which is a natural generalization of the classical linear singular vector and linear singular value to the nonlinear category. The optimization problem related to the determination of nonlinear singular vectors and singular values is formulated. The general idea of this approach is demonstrated by a simple two-dimensional quasigeostrophic model in the atmospheric and oceanic sciences. The advantage and its applications of the new method to the predictability, ensemble forecast and finite-time nonlinear instability are discussed. This paper makes a necessary preparation for further theoretical and numerical investigations.
Institute of Scientific and Technical Information of China (English)
王文祝; 金丰; 周海波
2013-01-01
During the controlling of the ultra-precision maglev movement ,the hysteresis existed in the iron core and the armature guide is an important reason of making it hard to control precisely . It is significant to study the law of the hysteresis characteristics'nonlinear influence on the elec-tromagnetic force and build its nonlinear model .Through studying the hysteresis characteristics'influence on the air-gap magnetic flux density in the maglev precision movement and analyzing the hysteresis modeling theory of the magnetic circuit with an air gap ,the nonlinear electromagnetic force model including the Jiles-Atherton model was established and then its parameters were test-ed by the particle swarm optimization .Results show that the electromagnet hysteresis in the ma-glev precision movement should not be neglected .The air-gap magnetic flux density calculated by the identified new model is more precise and closer to the measured value than that calculated by the traditional model .These results provide an important reference for improving control preci-sion of the maglev precision movement .% 超精密磁悬浮运动控制中，电磁铁铁心及衔铁导轨中存在的磁滞特性是导致电磁力难以实现精确控制的重要原因之一。研究磁滞特性对电磁力的非线性影响规律并建立其非线性模型具有重要意义。通过研究磁悬浮精密运动中电磁铁磁滞特性对气隙处磁感应强度的影响，分析了带气隙磁路磁滞特性建模原理，建立了包含Jiles-Atherton模型的电磁铁磁浮力非线性模型，并采用粒子群优化算法对该模型参数进行实验验证。结果表明，磁悬浮精密运动中电磁铁磁滞特性不容忽视，采用经参数辨识得到的新模型比采用传统模型计算得到的气隙磁感应强度值更精确、更接近实测值。研究结果为提高磁悬浮精密运动中电磁力的精确控制提供了重要参考价值。
Directory of Open Access Journals (Sweden)
Yang Zhang
2013-01-01
Full Text Available We introduce a continuum modeling method to approximate a class of large wireless networks by nonlinear partial differential equations (PDEs. This method is based on the convergence of a sequence of underlying Markov chains of the network indexed by N, the number of nodes in the network. As N goes to infinity, the sequence converges to a continuum limit, which is the solution of a certain nonlinear PDE. We first describe PDE models for networks with uniformly located nodes and then generalize to networks with nonuniformly located, and possibly mobile, nodes. Based on the PDE models, we develop a method to control the transmissions in nonuniform networks so that the continuum limit is invariant under perturbations in node locations. This enables the networks to maintain stable global characteristics in the presence of varying node locations.
Energy Technology Data Exchange (ETDEWEB)
Barus, R. P. P., E-mail: rismawan.ppb@gmail.com [Engineering Physics, Faculty of Industrial Technology, Institut Teknologi Bandung, Jalan Ganesa 10 Bandung and Centre for Material and Technical Product, Jalan Sangkuriang No. 14 Bandung (Indonesia); Tjokronegoro, H. A.; Leksono, E. [Engineering Physics, Faculty of Industrial Technology, Institut Teknologi Bandung, Jalan Ganesa 10 Bandung (Indonesia); Ismunandar [Chemistry Study, Faculty of Mathematics and Science, Institut Teknologi Bandung, Jalan Ganesa 10 Bandung (Indonesia)
2014-09-25
Fuel cells are promising new energy conversion devices that are friendly to the environment. A set of control systems are required in order to operate a fuel cell based power plant system optimally. For the purpose of control system design, an accurate fuel cell stack model in describing the dynamics of the real system is needed. Currently, linear model are widely used for fuel cell stack control purposes, but it has limitations in narrow operation range. While nonlinear models lead to nonlinear control implemnetation whos more complex and hard computing. In this research, nonlinear cancellation technique will be used to transform a nonlinear model into a linear form while maintaining the nonlinear characteristics. The transformation is done by replacing the input of the original model by a certain virtual input that has nonlinear relationship with the original input. Then the equality of the two models is tested by running a series of simulation. Input variation of H2, O2 and H2O as well as disturbance input I (current load) are studied by simulation. The error of comparison between the proposed model and the original nonlinear model are less than 1 %. Thus we can conclude that nonlinear cancellation technique can be used to represent fuel cell nonlinear model in a simple linear form while maintaining the nonlinear characteristics and therefore retain the wide operation range.
Institute of Scientific and Technical Information of China (English)
蔡仲昌; 刘辉; 项昌乐; 张喜清; 王明正
2012-01-01
A model was built for the forced torsional vibration excited by the dynamic torque of the engine in the vehicle multistage planetary transmission using the lumped parameter method,and the differential equations were derived by the Lagrangian equation and solved.The amplitude characteristics of the different parts in the same gear shift were analyzed,and their vibration behaviors were revealed.The vibrations of the planetary gear under different gear shifts were investigated,and the difference between the torsional vibrations of the planetary gear under load state and no-load state were obtained.The fluctuation of the meshing force of the planetary gear and the dynamic load coefficient were calculated,providing a basis for the design and the dynamic analysis of the multistage planetary transmission.%针对某车辆行星传动系统,以发动机动态转矩为激励,采用集中参数法建立纯扭转强迫振动模型,利用拉格朗日方程建立系统微分方程并进行求解。分析了各部件在同一档位的振幅特性,得出不同部件的振动特点。研究了不同档位下行星排的振动,得出行星排在空载与受载时扭振的差异。最后对行星排啮合力波动量和动载荷系数进行计算,为行星传动系统设计和动态分析提供了依据。
Institute of Scientific and Technical Information of China (English)
王志功; 吕晓迎; 高建芸; 王宇航; 黄岑宇; 陈明琳; 邢丽阳; 王桂英
2011-01-01
Study on features of acupoints with resistance test in the past half century is reviewed in this article. Mechanism and technology of the method are introduced as well as its shortcomings. The determination method of signal transmission along meridians with the combination of electrical network theories and practice is advanced. And the result of a series experiments on one meridian at the superficial part of the body are given as well. Thus, it is concluded that the signals of the point-in/point-out and the signals along a non-meridian path with the same distance are significantly different, which gives a verification of the feasibility of the method by using electrical network theories to set out characteristics of signal transmission along meridians dynamically.%回顾半个多世纪以来采用阻抗测试方法确定经穴特性的研究进展,介绍这一方法的原理和技术,指出这一方法存在的不足.提出采用电气网络理论与实验测定经穴信号传输特性的方法,给出迄今为止在体表围绕一条经络开展实验所得到的初步结果.用经络线上穴位点输入到穴位点输出获得的响应信号与非经络线上等距离位点响应信号的显著不同,验证采用电气网络理论动态测定经络信号传输特性的可行性.
MIMO Identical Eigenmode Transmission System (IETS) - A Channel Decomposition Perspective
Shakir, M Zeeshan
2010-01-01
In the past few years considerable attention has been given to the design of Multiple-Input Multiple-Output (MIMO) Eigenmode Transmission Systems (EMTS). This paper presents an in-depth analysis of a new MIMO eigenmode transmission strategy. The non-linear decomposition technique called Geometric Mean Decomposition (GMD) is employed for the formation of eigenmodes over MIMO flatfading channel. Exploiting GMD technique, identical, parallel and independent transmission pipes are created for data transmission at higher rate. The system based on such decomposition technique is referred to as MIMO Identical Eigenmode Transmission System (IETS). The comparative analysis of the MIMO transceiver design exploiting nonlinear and linear decomposition techniques for variable constellation is presented in this paper. The new transmission strategy is tested in combination with the Vertical Bell Labs Layered Space Time (V-BLAST) decoding scheme using different number of antennas on both sides of the communication link. The ...
Nonlinear susceptibility magnitude imaging of magnetic nanoparticles
Energy Technology Data Exchange (ETDEWEB)
Ficko, Bradley W., E-mail: Bradley.W.Ficko@Dartmouth.edu; Giacometti, Paolo; Diamond, Solomon G.
2015-03-15
This study demonstrates a method for improving the resolution of susceptibility magnitude imaging (SMI) using spatial information that arises from the nonlinear magnetization characteristics of magnetic nanoparticles (mNPs). In this proof-of-concept study of nonlinear SMI, a pair of drive coils and several permanent magnets generate applied magnetic fields and a coil is used as a magnetic field sensor. Sinusoidal alternating current (AC) in the drive coils results in linear mNP magnetization responses at primary frequencies, and nonlinear responses at harmonic frequencies and intermodulation frequencies. The spatial information content of the nonlinear responses is evaluated by reconstructing tomographic images with sequentially increasing voxel counts using the combined linear and nonlinear data. Using the linear data alone it is not possible to accurately reconstruct more than 2 voxels with a pair of drive coils and a single sensor. However, nonlinear SMI is found to accurately reconstruct 12 voxels (R{sup 2}=0.99, CNR=84.9) using the same physical configuration. Several time-multiplexing methods are then explored to determine if additional spatial information can be obtained by varying the amplitude, phase and frequency of the applied magnetic fields from the two drive coils. Asynchronous phase modulation, amplitude modulation, intermodulation phase modulation, and frequency modulation all resulted in accurate reconstruction of 6 voxels (R{sup 2}>0.9) indicating that time multiplexing is a valid approach to further increase the resolution of nonlinear SMI. The spatial information content of nonlinear mNP responses and the potential for resolution enhancement with time multiplexing demonstrate the concept and advantages of nonlinear SMI. - Highlights: • Development of a nonlinear susceptibility magnitude imaging model • Demonstration of nonlinear SMI with primary and harmonic frequencies • Demonstration of nonlinear SMI with primary and intermodulation
Supratransmission in a disordered nonlinear periodic structure
Yousefzadeh, B.; Phani, A. Srikantha
2016-10-01
We study the interaction among dispersion, nonlinearity, and disorder effects in the context of wave transmission through a discrete periodic structure, subjected to continuous harmonic excitation in its stop band. We consider a damped nonlinear periodic structure of finite length with disorder. Disorder is introduced throughout the structure by small changes in the stiffness parameters drawn from a uniform statistical distribution. Dispersion effects forbid wave transmission within the stop band of the linear periodic structure. However, nonlinearity leads to supratransmission phenomenon, by which enhanced wave transmission occurs within the stop band of the periodic structure when forced at an amplitude exceeding a certain threshold. The frequency components of the transmitted waves lie within the pass band of the linear structure, where disorder is known to cause Anderson localization. There is therefore a competition between dispersion, nonlinearity, and disorder in the context of supratransmission. We show that supratransmission persists in the presence of disorder. The influence of disorder decreases in general as the forcing frequency moves away from the pass band edge, reminiscent of dispersion effects subsuming disorder effects in linear periodic structures. We compute the dependence of the supratransmission force threshold on nonlinearity and strength of coupling between units. We observe that nonlinear forces are confined to the driven unit for weakly coupled systems. This observation, together with the truncation of higher-order nonlinear terms, permits us to develop closed-form expressions for the supratransmission force threshold. In sum, in the frequency range studied here, disorder does not influence the supratransmission force threshold in the ensemble-average sense, but it does reduce the average transmitted wave energy.
Institute of Scientific and Technical Information of China (English)
杨瑗; 金李; 何英利; 刘锦锋; 王静; 王科; 马晓华; 李倩; 冯玉岭
2016-01-01
Objective To investigate the characteristics of hepatitis B virus (HBV) transmission among family members in families with familial clustering of HBV infection and poor outcomes,as well as the prevalence and distribution characteristics of HBsAg in offspring with different parental HBsAg status.Methods The general information of each member in families with poor outcomes were collected from 2007 to 2010,and serological test was performed to analyze the prevalence and distribution of HBsAg in family members.The chi-square test or Fisher's exact test was used to analyze and compare the sex of offspring and the prevalence of HBsAg in them in 266 nuclear families with different paternal and maternal HBsAg status.Results The positive rates of HBsAg in parents,siblings,children,and spouses of the probands were 20％,88.2％,76.8％,and 9.5％,respectively.The nuclear families with HBsAg-positive fathers and HBsAg-negative mothers had a significantly increased proportion of male offspring (male/female ratio =2.02) compared with those with HBsAg-positive mothers and HBsAg-negative fathers (1.22) or those with HBsAg-negative fathers and mothers (0.96).In addition,in the nuclear families with HBsAg-positive fathers and HBsAg-negative mothers,the male offspring had a significantly higher HBsAg positive rate than female offspring (37.4％ vs 13.8％),while in those with HBsAg-positive mothers and HBsAg-negative fathers or those with HBsAg-negative fathers and mothers,HBsAg positive rate showed no significant difference between male and female offspring.Conclusion In families with familial clustering of HBV infection and poor outcomes,mother-to-child transmission is still the major route of HBV transmission,but father-to-child transmission also plays a role in HBV transmission in this special population.Positive HBsAg in fathers is associated with the increased proportion of male offspring,and father-to-son transmission of HBV is higher than father-to-daughter transmission
Institute of Scientific and Technical Information of China (English)
许金; 马伟明; 鲁军勇; 孙兆龙; 张育兴
2012-01-01
A novel slot-less double-sided long-stator linear induction motor is proposed for the application of Electromagnetic Launch. In this motor, the conventional gullet structure is cancelled, and conductive area of the motor stator windings is enlarged, and then the loss and temperature rise is decreased. Based on the finite element simulation and calculation of electromagnetic field, the saturation characteristics of stator leakage inductance and excitation inductance are obtained, and the calculation methods in nonlinear conditions of the motor are displayed. The comparison of experimental and calculation results verifies the validity and superiority of the proposed calculation methods.%提出了一种应用于电磁发射场合的新型无槽双边长定子直线感应电机，该电机取消了传统电机的齿槽结构，增大了电机定子绕组的导电面积，降低了电机损耗和温升。基于电磁场有限元仿真计算得到了电机定子漏感和励磁电感的饱和特性，给出了电机非线性工况的计算方法。实验结果和计算结果的比较验证了计算方法的正确性。
Directory of Open Access Journals (Sweden)
R. N. Bhowmik
2015-06-01
Full Text Available We have studied current-voltage (I-V characteristics of α-Fe1.64Ga0.36O3, a typical canted ferromagnetic semiconductor. The sample showed a transformation of the I-V curves from linear to non-linear character with the increase of bias voltage. The I-V curves showed irreversible features with hysteresis loop and bi-stable electronic states for up and down modes of voltage sweep. We report positive magnetoresistance and magnetic field induced negative differential resistance as the first time observed phenomena in metal doped hematite system. The magnitudes of critical voltage at which I-V curve showed peak and corresponding peak current are affected by magnetic field cycling. The shift of the peak voltage with magnetic field showed a step-wise jump between two discrete voltage levels with least gap (ΔVP 0.345(± 0.001 V. The magnetic spin dependent electronic charge transport in this new class of magnetic semiconductor opens a wide scope for tuning large electroresistance (∼500-700%, magnetoresistance (70-135 % and charge-spin dependent conductivity under suitable control of electric and magnetic fields. The electric and magnetic field controlled charge-spin transport is interesting for applications of the magnetic materials in spintronics, e.g., magnetic sensor, memory devices and digital switching.
Institute of Scientific and Technical Information of China (English)
焦在滨; 齐倩; 杨黎明; 王优胤; 宁荣
2014-01-01
受电容式电压互感器(capacitive voltage transformer， CVT)暂态特性的影响，高压输电线路距离保护易发生暂态超越而误动，影响电力系统的安全稳定运行。提出了一种不受 CVT 暂态特性影响的距离保护新原理。该原理以 CVT能够正确传变工频量为基础，通过基于矩阵束的准确工频量提取方法计算保护安装处电压电流的工频量，利用贝瑞龙模型计算长距离输电线路整定点处的电压和电流，最终以整定点为观测点，通过传统的距离保护算法与方向元件配合确定故障点的位置，该原理不受CVT暂态特性的影响，同时考虑了长距离输电线路分布参数效应对距离保护的影响，具有较好的性能，仿真结果验证了所提算法的有效性。%Affected by transient characteristic of capacitor voltage transformer (CVT), the distance protection for HV transmission line is easily to mal-operate due to transient overreach, thus the secure and stable operation of power grid is affected. A new distance protection scheme that is not affected by the transient characteristics of CVT is proposed and its principle is as following:firstly, on the basis that the CVT can transmit and transform power frequency phasor, by means of the matrix pencil based accurate power frequency phasor extraction method the power frequency phasors of voltage and current at the position where the protection is installed are calculated;secondly, the voltage and current at the position of the long distance transmission line, where the protection is set, are calculated by Bergeron model; finally, coordinating with directional element and taking the setting point as the observation point, the fault point is located by traditional distance protection algorithm. The proposed principle is not affected by transient characteristic of CVT and the impacts of distributed parameters of the long distance transmission line are taken into account, thus the
Non-linear wave propagation in acoustically lined circular ducts
Nayfeh, A. H.; Tsai, M.-S.
1974-01-01
An analysis is presented of the nonlinear effects of the gas motion as well as of the acoustic lining material on the transmission and attenuation of sound in a circular duct with a uniform cross-section and no mean flow. The acoustic material is characterized by an empirical, nonlinear impedance in which the instantaneous resistance is a nonlinear function of both the frequency and the acoustic velocity. The results show that there exist frequency bandwidths around the resonant frequencies in which the nonlinearity decreases the attenuation rate, and outside which the nonlinearity increases the attenuation rate, in qualitative agreement with experimental observations. Moreover, the effect of the gas nonlinearity increases with increasing sound frequency, whereas the effect of the material nonlinearity decreases with increasing sound frequency.
Nonlinear time reversal of classical waves: experiment and model.
Frazier, Matthew; Taddese, Biniyam; Xiao, Bo; Antonsen, Thomas; Ott, Edward; Anlage, Steven M
2013-12-01
We consider time reversal of electromagnetic waves in a closed, wave-chaotic system containing a discrete, passive, harmonic-generating nonlinearity. An experimental system is constructed as a time-reversal mirror, in which excitations generated by the nonlinearity are gathered, time-reversed, transmitted, and directed exclusively to the location of the nonlinearity. Here we show that such nonlinear objects can be purely passive (as opposed to the active nonlinearities used in previous work), and we develop a higher data rate exclusive communication system based on nonlinear time reversal. A model of the experimental system is developed, using a star-graph network of transmission lines, with one of the lines terminated by a model diode. The model simulates time reversal of linear and nonlinear signals, demonstrates features seen in the experimental system, and supports our interpretation of the experimental results.
Non-linear dynamics of a spur gear pair
Kahraman, A.; Singh, R.
1990-10-01
Non-linear frequency response characteristics of a spur gear pair with backlash are examined in this paper for both external and internal excitations. The internal excitation is of importance from the high frequency noise and vibration control viewpoint and it represents the overall kinematic or static transmission error. Such problems may be significantly different from the rattle problems associated with external, low frequency torque excitation. Two solution methods, namely the digital simulation technique and the method of harmonic balance, have been used to develop the steady state solutions for the internal sinusoidal excitation. Difficulties associated with the determination of the multiple solutions at a given frequency in the digital simulation technique have been resolved, as one must search the entire initial conditions map. Such solutions and the transition frequencies for various impact situations are easily found by the method of harmonic balance. Further, the principle of superposition can be employed to analyze the periodic transmission error excitation and/or combined excitation problems provided that the excitation frequencies are sufficiently apart from each other. Our analytical predictions match satisfactorily with the limited experimental data available in the literature. Using the digital simulation, we have also observed that the chaotic and subharmonic resonances may exist in a gear pair depending upon the mean or design load, mean to alternating force ratio, damping and backlash. Specifically, the mean load determines the conditions for no impacts, single-sided impacts and double-sided impacts. Our results are different from the frequency response characteristics of the conventional, single-degree-of-freedom, clearance type non-linear system. Our formulation should form the basis of further analytical and experimental work in the geared rotor dynamics area.
Mode matching for optimal plasmonic nonlinear generation
O'Brien, Kevin; Suchowski, Haim; Rho, Jun Suk; Kante, Boubacar; Yin, Xiaobo; Zhang, Xiang
2013-03-01
Nanostructures and metamaterials have attracted interest in the nonlinear optics community due to the possibility of engineering their nonlinear responses; however, the underlying physics to describe nonlinear light generation in nanostructures and the design rules to maximize the emission are still under debate. We study the geometry dependence of the second harmonic and third harmonic emission from gold nanostructures, by designing arrays of nanostructures whose geometry varies from bars to split ring resonators. We fix the length (and volume) of the nanostructure on one axis, and change the morphology from a split ring resonator on the other axis. We observed that the optimal second harmonic generation does not occur at the morphology indicated by a nonlinear oscillator model with parameters derived from the far field transmission and is not maximized by a spectral overlap of the plasmonic modes; however, we find a near field overlap integral and mode matching considerations accurately predict the optimal geometry.