线路线形的单元模型及构线方法

线路线形复杂多样,文中通过对各种线形几何模型的分析,建立了单一的线形单元数学模型,并以此为基础形成了一套数据结构统一的构造线形的有效方法,使构造线形过程简明、快捷又易于掌握。

Modelling of ultrasonic motor with dead-zone based on Hammerstein model structure

The ultrasonic motor (USM) possesses heavy nonlinearities which vary with driving conditions and load-dependent characteristics such as the dead-zone. In this paper, an identification method for the rotary travelling-wave type ultrasonic motor (RTWUSM) with dead-zone is proposed based on a modified Hammerstein model structure. The driving voltage contributing effect on the nonlinearities of the RTWUSM was transformed to the change of dynamic parameters against the driving voltage. The dead-zone of the RTWUSM is identified based upon the above transformation. Experiment results showed good agreement be- tween the output of the proposed model and actual measured output.

Electronic Structure Analysis of USiO_4

Uranium is a member of Actinides and plays important role in nuclear science and technology. Electronicand structural investigations of actinide compounds attract major interest in science. The electronic structure andchemical bonding of coffinite USiO_4 are investigated by X-ray Absorption Fine Structure spectroscopy (XAFS). U L_3-edge absorption spectrum in USiO_4 is compared with U L_3-edge spectra in UO_2 and UTe due to their different electronicand chemical structures. The study presents XANES (x-ray Absorption Near-Edge Structure) and Extended XAFS(EXAFS) calculations of USiO_4 thin films. The full multiple scattering approach has been applied to the calculation ofU L_3 edge XANES spectra of USiO_4, UO_2 and UTe, based on different choices of one electron potentials according toUranium coordinations by using the real space multiple scattering method FEFF 8.2 code.

su(1,2) Algebraic Structure of XYZ Antiferromagnetic Model in Linear Spin-Wave Frame

The XYZ antiferromagnetic model in linear spin-wave frame is shown explicitly to have an su（1,2） algebraic structure： the Hamiltonian can be written as a linear function of the su（1,2） algebra generators. Based on it, the energy eigenvalues are obta/ned by making use of the similar transformations, and the algebraic diagonalization method is investigated. Some numerical solutions are given, and the results indicate that only one group solution could be accepted in physics.

Numerical Investigations on Transient Behaviours of Two 3-D Freely Floating Structures by Using a Fully Nonlinear Method

Two floating structures in close proximity are very commonly seen in offshore engineering. They are often subjected to steep waves and, therefore, the transient effects on their hydrodynamic features are of great concem. This paper uses the quasi arbitrary Lagrangian Eulerian finite element method （QALE-FEM）, based on the fully nonlinear potential theory （FNPT）, to numerically investigate the interaction between two 3-D floating structures, which undergo motions with 6 degrees of freedom （DOFs）, and are subjected to waves with different incident angles. The transient behaviours of floating structures, the effect of the accompanied structures, and the nonlinearity on the motion of and the wave loads on the structures are the main focuses of the study. The investigation reveals an important transient effects causing considerably larger structure motion than that in steady state. The results also indicate that the accompanied structure in close proximity enhances the interaction between different motion modes and results in stronger nonlinearity causing 2hal-order component to be of similar significance to the fundamental one.

New Integrable Decomposition of Super AKNS Equation

In this paper, a new 7×7 matrix spectral problem, which is associated with the super AKNS equation isconstructed.With the use of the binary nonlinearization method, a new integrable decomposition of the super AKNSequation is presented.

Nonlinear finite-element-based structural system failure probability analysis methodology for gravity dams considering correlated failure modes

The structural system failure probability(SFP) is a valuable tool for evaluating the global safety level of concrete gravity dams.Traditional methods for estimating the failure probabilities are based on defined mathematical descriptions,namely,limit state functions of failure modes.Several problems are to be solved in the use of traditional methods for gravity dams.One is how to define the limit state function really reflecting the mechanical mechanism of the failure mode;another is how to understand the relationship among failure modes and enable the probability of the whole structure to be determined.Performing SFP analysis for a gravity dam system is a challenging task.This work proposes a novel nonlinear finite-element-based SFP analysis method for gravity dams.Firstly,reasonable nonlinear constitutive modes for dam concrete,concrete/rock interface and rock foundation are respectively introduced according to corresponding mechanical mechanisms.Meanwhile the response surface(RS) method is used to model limit state functions of main failure modes through the Monte Carlo(MC) simulation results of the dam-interface-foundation interaction finite element(FE) analysis.Secondly,a numerical SFP method is studied to compute the probabilities of several failure modes efficiently by simple matrix integration operations.Then,the nonlinear FE-based SFP analysis methodology for gravity dams considering correlated failure modes with the additional sensitivity analysis is proposed.Finally,a comprehensive computational platform for interfacing the proposed method with the open source FE code Code Aster is developed via a freely available MATLAB software tool(FERUM).This methodology is demonstrated by a case study of an existing gravity dam analysis,in which the dominant failure modes are identified,and the corresponding performance functions are established.Then,the dam failure probability of the structural system is obtained by the proposed method considering the correlation relationship of main failure modes on the basis of the mechanical mechanism analysis with the MC-FE simulations.

A 14.5Gb/s word alignment circuit in 0.18μm CMOS technology for high-speed SerDes

This paper presents a word alignment circuit for high speed SerDes system.By using pipeline structure and circuit optimization techniques,the speed of the aligner is increased,and its performance is improved further through adopting the full custom design method.The proposed word aligner has fabricated in 0.18μm CMOS technology with total area of 1.075 ×0.775mm^2￣ including I/O pad.Measurement results show that this circuit achieves the maximum data rate of 14.5Gb/s,while consuming a total power of 34.9mW from a 1.8V supply.

Heteroclinic Breather-Wave Solutions for Davey-Stewartson Equation

Exact heteroclinic breather-wave solutions for Davey-Stewartson （DSI, DSII） system with periodic boundary condition are constructed using Hirota＇s bilinear form method and generalized ansatz method. The heteroclinic structure of wave is investigated.

Linear and Non-linear Hydrodynamic Analysis for Structural Load of a Pipe-Laying Ship

The first decision we need to make in a structural load assessment is what approach should be applied, a linear approach or a non-linear one. The correct decision comes from understanding of the technology used in the linear and non-linear approaches and also comes from the understanding of the problem to he analyzed. From engineering practice, it has been found that many non-linear effects can be taken into account in a linear model with appropriate approach. A study of hydrodynamic structural load on a stinger of a pipe-laying vessel is presented in this paper. The results of a non-linear analysis are compared to those of linear models with different approaches, and how the nonlinear effect can be involved in a linear model is discussed. The recommendations on how to estimate the non-linear effects in a linear structural load model is discussed.

The Straight-Line Depreciation Method Used by Selected Companies and Educational Institutions in the Philippines

The straight-line method in computing for depreciation expense is the prevailing method used in the Philippines. This paper aims to determine the rationale behind the use of this method. The objective of the study is to determine the length of time within which the depreciation method is used, reasons in using the method, the rate of depreciation used by the companies, and the effects of the depreciation expense on their operating expenses. It also determines if the companies＇ decisions to use the straight-line method are influenced by the factors mentioned by Reynolds （196 I）----expected amount of services over the life of assets, the amount and timing of operating costs, the decline in the physical efficiency of the assets, and the rate of return--and if they considered capital investments and tax reduction in using this method. The study shows that companies and educational institutions use the straight-line method of computing depreciation expenses, because it is easy to use in computing the depreciation expenses, in comparing with previous years＇ computations, and in keeping track of the expenses. It is also convenient for tax administration and financial reporting. The rate of depreciation used varies, because the companies and educational institutions use their past experiences in determining the life of fixed assets. The percentage of depreciation to the operating expenses also varies. The companies and educational institutions adhered to the factors mentioned by Reynolds （1961） in choosing the straight-line method of depreciation. The companies did not consider reduction of tax in using the straight-line method.

Dynamic Analysis of Kineto-Elastic Beam System with Second-order Effect

Dynamic equations of motional flexible beam elements were derived considering second-order effect. Non-linear finite element method and three-node Euler-Bernoulli beam elements were used. Because accuracy is higher in non-linear structural analysis,three-node beam elements are used to deduce shape functions and stiffness matrices in dynamic equations of flexible elements. Static condensation method was used to obtain the finial dynamic equations of three-node beam elements. According to geometrical relations of nodal displacements in concomitant and global coordinate system,dynamic equations of elements can be transformed to global coordinate system by concomitant coordinate method in order to build the global dynamic equations. Analyzed amplitude condition of flexible arm support of a port crane,the results show that second-order effect should be considered in kinetic-elastic analysis for heavy load machinery of big flexibility.

Stabilization of Hyperbolic Chaos by the Pyragas Method

For a long time it was a common opinion that hyperbolic attractors are artificial mathematical constructions. However, in the recent papers there were proposed physically realizable systems that possess, in their phase space, the set with features that are very similar to hyperbolic type of attractors. As is known, invariant sets are called hyperbolic attractors of the dynamical system if they are closed, topologically transitive subsets, and every their trajectory possesses uniform hyperbolicity. Very familiar types of the hyperbolic attractors are Smale-Williams＇ solenoid and Plykin＇s attractor. Further, it is well known that chaotic systems are very sensitive to the external perturbations. This property is used for controlling nonlinear systems and chaos suppression. Thus, an important question arises： Is it possible to suppress chaos in systems with hyperbolic attractors because these attractors are structurally stable subsets？ In the present contribution we study the possibility of stabilization of chaotic oscillations in systems with the Smale-Williams hyperbolic attractors by means of the Pyragas method with a delay. It is shown that by means of external perturbation the dynamical system could be controllable： the hyperbolic attractor degenerates into a periodic one.

Data-based model free hysteresis identification for a nonlinear structure

In the last two decades, the damage detection for civil engineering structures has been widely treated as a modal analysis problem and most of the currently available vibration-based system identification approaches are based on modal parameters, namely the natural frequencies, mode shapes and damping ratios, and/or their derivations, which are suitable for linear systems. Nonlinearity is generic in engineering structures. For example, the initiation and development of cracks in civil engineering structures as typical structural damages are nonlinear process. One of the major challenges in damage detection, early warning and damage prognosis is to obtain reasonably accurate identification of nonlinear performance such as hysteresis which is the direct indicator of damage initiation and development under dynamic excitations. In this study, a general data-based identification approach for hysteretic performance in form of nonlinear restoring force using structural dynamic responses and complete and incomplete excitation measurement time series was proposed and validated with a 4-story frame structure equipped with smart devices of magneto-theological （MR） damper to simulate nonlinear performance. Firstly, as an optimization method, the least-squares technique was employed to identify the system matrices of an equivalent linear system of the nonlinear structure model basing on the exci- tation force and the corresponding vibration measurements with impact test when complete and incomplete excitations; and secondly, the nonlinear restoring force of the structure was identified and compared with the test measurements fi- nally. Results show that the proposed data-based approach is capable of identifying the nonlinear behavior of engineering structures and can be employed to evaluate the damage initiation and development of different structure under dynamic loads.

A robust and efficient structural reliability method combining radial-based importance sampling and Kriging

Simulation based structural reliability analysis suffers from a heavy computational burden, as each sample needs to be evaluated on the performance function, where structural analysis is performed. To alleviate the computational burden, related research focuses mainly on reduction of samples and application of surrogate model, which substitutes the performance function. However,the reduction of samples is achieved commonly at the expense of loss of robustness, and the construction of surrogate model is computationally expensive. In view of this, this paper presents a robust and efficient method in the same direction. The present method uses radial-based importance sampling (RBIS) to reduce samples without loss of robustness. Importantly, Kriging is fully used to efficiently implement RBIS. It not only serves as a surrogate to classify samples as we all know, but also guides the procedure to determine the optimal radius, with which RBIS would reduce samples to the highest degree. When used as a surrogate, Kriging is established through active learning, where the previously evaluated points to determine the optimal radius are reused. The robustness and efficiency of the present method are validated by five representative examples, where the present method is compared mainly with two fundamental reliability methods based on active learning Kriging.

Thermal performances of non-equidistant helical-coil phase change accumulator for latent heat storage

Helical-coil is a common structure of heat exchanger unit in phase change heat accumulator and usually has the equal coil pitch between adjacent coils. Its thermal performances could be improved by improving the uniformity of the phase change material （PCM） temperature distribution. Thus, a novel non-equidistant helical-coil structure was proposed in this study. Its coil pitch decreased along the flow direction of heat transfer fluid, which made the heat exchange area in unit volume increase to match the decreasing temperature difference between the heat transfer fluid and PCM. The structure was optimized using numerical simulation. An experimental system was developed and the experiment results indicated that the proposed non-equidistant helical-coil heat accumulator was more effective than equidistant helical-coil for latent heat storage. The uniformity of the temperaalre distribution was also confirmed by simulation results.

Generalized Lagrange Jacobi Gauss-Lobatto (GLJGL) Collocation Method for Solving Linear and Nonlinear Fokker-Planck Equations

In this study, we have constructed a new numerical approach for solving the time-dependent linear and nonlinear Fokker-Planck equations. In fact, we have discretized the time variable with Crank-Nicolson method and for the space variable, a numerical method based on Generalized Lagrange Jacobi Gauss-Lobatto(GLJGL) collocation method is applied. It leads to in solving the equation in a series of time steps and at each time step, the problem is reduced to a problem consisting of a system of algebraic equations that greatly simplifies the problem. One can observe that the proposed method is simple and accurate. Indeed, one of its merits is that it is derivative-free and by proposing a formula for derivative matrices, the difficulty aroused in calculation is overcome, along with that it does not need to calculate the General Lagrange basis and matrices; they have Kronecker property. Linear and nonlinear Fokker-Planck equations are given as examples and the results amply demonstrate that the presented method is very valid, effective,reliable and does not require any restrictive assumptions for nonlinear terms.

Stair and Step Soliton Solutions of the Integrable (2+1) and (3+1)-Dimensional Boiti-Leon-Manna-Pempinelli Equations

The multiple exp-function method is a new approach to obtain multiple wave solutions of nonlinear partial differential equations (NLPDEs). By this method one can obtain multi-soliton solutions of NLPDEs. In this paper, using computer algebra systems, we apply the multiple exp-function method to construct the exact multiple wave solutions of a (2+1)-dimensional Boiti-Leon-Manna-Pempinelli equation. Also, we extend the equation to a (3+1)-dimensional case and obtain some exact solutions for the new equation by applying the multiple exp-function method. By these applications, we obtain single-wave, double-wave and multi-wave solutions for these equations.

Twists and turns—How we stepped into and had fun in the “boring” lipid field

Compared to proteins and RNAs, functional specificities associated with structural variations in fatty acids and lipids have been greatly underexplored. This review describes how our lab naively started to work on lipids 14 years ago, and how we have gradually overcome obstacles to address some interesting biological questions by combining genetics with biochemical methods on the nematode Caenorhabditis elegans. Our studies have revealed lipid variants and their metabolic pathways, in specific tissues, impact development and behaviors by regulating specific signaling events. The review also discusses the general research approach, style of lab management, and funding mechanisms that have facilitated the frequent research direction changes in the lab, including the journey into the lipid field.

An efficient time-integration method for nonlinear dynamic analysis of solids and structures

This paper presents an efficient time-integration method for obtaining reliable solutions to the second-order nonlinear dynamic problems in structural engineering. This method employs both the backward-acceleration differentiation formula and the trapezoidal rule, resulting in a self-starting, single step, second-order accurate algorithm. With the same computational effort as the trapezoidal rule, the proposed method remains stable in large deformation and long time range solutions even when the trapezoidal rule fails. Meanwhile, the proposed method has the following characteristics: (1) it is applicable to linear as well as general nonlinear analyses; (2) it does not involve additional variables (e.g. Lagrange multipliers) and artificial parameters; (3) it is a single-solver algorithm at the discrete time points with symmetric effective stiffness matrix and effective load vectors; and (4) it is easy to implement in an existing computational software. Some numerical results indicate that the proposed method is a powerful tool with some notable features for practical nonlinear dynamic analyses.