Numerical analysis of superposed GSPNs

The numerical analysis of various modeling formalisms profits from a structured representation for the generator matrix Q of the underlying continuous-time Markov chain, where Q is described by a sum of tensor (Kronecker) products of much smaller matrices. In this paper, we describe such a representation for the class of superposed generalized stochastic Petri nets (GSPNs), which is less restrictive than in previous work. Furthermore a new iterative analysis algorithm is proposed. It pays special attention to a memory-efficient representation of iteration vectors as well as to a memory-efficient structured representation of Q in consequence the new algorithm is able to solve models which have state spaces with several million states, where other exact numerical methods become impracticable on a common workstation     

Binary superposed quantum decision diagrams

Binary superposed decision diagrams (BSQDDs) are a new type of quantum decision diagram that can be used for representing arbitrary quantum superpositions. One major advantage of BSQDDs is that they are dependent on the types of gates used in synthesis and a BSQDD can be used to efficiently generate a quantum array that will initialize the quantum superposition that the BSQDD represents. Transformation rules for BSQDDs allow BSQDDs to be reduced into simpler BSQDDs that represent the same quantum superposition. Canonical forms exist for a broad class of BSQDDs. This allows BSQDDs to be used for synthesizing quantum arrays that are capable of initializing arbitrary quantum superpositions.     

Transient analysis of stochastic fluid models

We analyze the transient behavior of stochastic fluid flow models in which the input and output rates are controlled by a finite homogeneous Markov process. Such models are used in asynchronous transfer mode (ATM) to evaluate the performance of fast packet switching and in manufacturing systems for the performance of producers and consumers coupled by a buffer. The transient analysis of such models has already been considered in earlier works and solutions have been obtained by the use of Laplace transform. We derive in this paper a new transient solution only based on recurrence relations. We show that this solution is particularly interesting for its numerical properties. The limiting behavior of the solution is also considered. We empirically show that the algorithm for computing the transient solution can be stopped when some stationary behavior is detected.     

Character of superposed states under deterministic LOCC

In this paper we investigate the effect of superposition of states on local conversion of pure bipartite states under deterministic LOCC. We are able to form a bridge between comparable and incomparable classes of states through the linear superposition of states. For example, if we consider two pairs of incomparable states, then their superposition may result into a comparable pair of states. We investigate many such cases and provide some of the results in tabular form. We also investigate the entanglement behavior of such classes of states, specifically their monotone nature. Finally we provide some bounds of different measures of entanglement based on the idea of comparability and incomparability under deterministic LOCC.     

Transient dynamic analysis of ferro-fluid bearing spindle motor

 With areal recording density of hard disk drives (HDD) historically growing at an average of 60% per year and fast spindle speed to continue to reduce access time, it is becoming increasingly more difficult to maintain the precise positioning required of the GMR heads to read and write data. Any unexpected vibration will cause the data written to a wrong data track. Consequently, the dynamic behaviors of HDD spindle systems and their potential influences on track misregistration are key issues in disk drive design. With rapid advances in the emerging consumer device market, the fluid bearing spindle motors, which have low NRRO, low acoustic noise and high damping, are being developed as next generation spindles. This paper is to study transient dynamic performance of HDD ferro-fluid bearing spindle systems. The FEA based component mode synthesis method is used to reduce the overall spindle system dimensions. The effect of the unbalanced magnetic pulls (UMP) due to two different types of motor configurations (balanced and unbalanced configurations) on the dynamic behaviors of spindle system was investigated. The simulated results show that the motor with balanced configuration provides better spindle dynamic performance due to absence of UMP. The UMP derived from the unbalanced configuration can result in some frequency resonance interactions and adversely affect the HDD servo-tracking system. Received: 5 July 2001/Accepted: 17 October 2001     

Transient analysis of structures by stiffly stable methods

The equation of motion for a general structure can be cast as a system of second order ordinary differential equations in discretized form. The locus of the roots for the homogeneous form of these equations is analyzed and related to the stability region for general, stiffly stable, linear multistep methods. The problem of recasting the second order system as a first order system is analyzed, noting that the final system to be solved is no larger than the original system. A discussion of error control is included and some specific formulas are given. Finally, a new family of third order formulas with a number of advantages over previously published formulas is given.     

Classical and superposed learning for quantum weightless neural networks

A supervised learning algorithm for quantum neural networks (QNN) based on a novel quantum neuron node implemented as a very simple quantum circuit is proposed and investigated. In contrast to the QNN published in the literature, the proposed model can perform both quantum learning and simulate the classical models. This is partly due to the neural model used elsewhere which has weights and non-linear activations functions. Here a quantum weightless neural network model is proposed as a quantisation of the classical weightless neural networks (WNN). The theoretical and practical results on WNN can be inherited by these quantum weightless neural networks (qWNN). In the quantum learning algorithm proposed here patterns of the training set are presented concurrently in superposition. This superposition-based learning algorithm (SLA) has computational cost polynomial on the number of patterns in the training set.     

Transient analysis and simulation of nonuniform lossy transmission lines

A new formulation of equations of the nonuniform lossy transmission line, in the form of integral equations based on the method of characteristics, has been introduced. Two methods of solution of these equations are presented, the first based on discretization of the integrals and, the second, a method of successive approximations, are presented and the results are compared. The presented integral equations of the line have interesting circuit representations and exhibit wave processes such as reflection, distortion, and attenuation. © 1992 John Wiley & Sons, Inc.     

Transient analysis of non-Markovian models using stochastic state classes

The method of stochastic state classes approaches the analysis of Generalised Semi Markov Processes (GSMPs) through the symbolic derivation of probability density functions over supports described by Difference Bounds Matrix (DBM) zones. This makes steady state analysis viable, provided that at least one regeneration point is visited by every cyclic behaviour of the model.We extend the approach providing a way to derive transient probabilities. To this end, stochastic state classes are extended with a supplementary timer that enables the symbolic derivation of the distribution of time at which a class can be entered. The approach is amenable to efficient implementation when model timings are given by expolynomial distributions, and it can be applied to perform transient analysis of GSMPs within any given time bound. In the special case of models underlying a Markov Regenerative Process (MRGP), the method can also be applied to the symbolic derivation of local and global kernels, which in turn provide transient probabilities through numerical integration of generalised renewal equations. Since much of the complexity of this analysis is due to the local kernel, we propose a selective derivation of its entries depending on the specific transient measure targeted by the analysis.     

Transient performance analysis in robust nonlinear adaptive control

This paper deals with the problem of controlling unknown linear systems in the presence of strictly proper unmodelled dynamics and bounded disturbances. Adaptive controllers that ensure the closed-loop global (uniform) stability and asymptotic performances can be designed following either the backstepping approach or the certainty-equivalence method. The main shortcoming of the involved controllers is that they do not allow quantification of the closed-loop transient behaviour. In this paper, the transient issue is addressed for backstepping adaptive controllers. A L_∞ bound on the tracking error is explicitly given as a function of the design parameters. This shows that the error can be made arbitrarily small by sufficiently increasing the design gains.     

Transient analysis of sharp thermal gradients using coarse finite element meshes

This paper investigates the application of the generalized finite element method with global–local enrichments (GFEM^gl) to problems of transient heat transfer involving localized features. The GFEM^gl is utilized in order to numerically construct general, specially-tailored shape functions yielding high levels of accuracy on coarse FEM meshes. The use of time-dependent shape functions requires that the system of equations be discretized temporally first, and then spatially in order to properly account for the time-dependency. The standard α-method is used for the time integration scheme. The transient three-dimensional GFEM^gl is then applied to a laser heating example in order to demonstrate its ability to resolve localized, transient features on a fixed, coarse mesh. Convergence analysis of the proposed method as well as applications to heterogeneous materials, and moving heat sources are also provided.     

Transient analysis of structural members by the CSDT riccati transfer matrix method

A method for the direct integration of the dynamic governing partial differential equations of motion for structural members is developed. This technique is called the continuous-space discrete-time (CSDT) Riccati transfer matrix method. This formulation transforms a boundary value problem of governing partial differential equations of motion into a boundary value problem of ordinary differential equations. First, a standard procedure such as finite differences is employed to discretize the time derivatives. Then, a line solution technique such as the Riccati transfer matrix method is utilized to integrate the spatial derivatives. The stability and accuracy of the CSDT Riccati transfer matrix method using the Newmark generalized acceleration formulation for time discretization is studied. For a particular class of governing equations, it is shown that the method is unconditionally stable without amplitude decay error for particular parameter values in the Newmark formulation. The method, however, exhibits period elongation error as a function of the time step. Numerical results for bar and beam example problems indicate that this may well be a viable method for calculating the dynamic response of linear structural members.     

Transient analysis of multi-server queues with Markov-modulated Poisson arrivals and overload control

This paper studies the transient behavior of a Markov-molulated Poisson arrival queue under overload control. The queue has finite or infinite buffer capacity with multiple exponential servers. A Markov-modulated Poisson process is used to represent an aggregated voice or video packet arrival process in integrated service networks. By overload control, we mean to properly adapt the arrival process once the buffer contents exceed a designated level. The probability distribution of queue length as a function of time is obtained. The temporal effect of the overload control is measured in two forms. While in overload, we measure the amount of time for the queue to fall into underload. While in underload, we measure the amount of time for the queue to rise to overload. A proper design of the control will not only reduce the fall time but also increase the rise time. We also explore the transient queueing behavior as affected by time stochastic properties of the underlying Markov chain for the arrival process.     

Transient analysis of packet discarding policies in ATM networks with correlated arrivals

In this paper, we investigate several dynamic congestion control strategies in ATM networks. We present an analytic model to observe the transient behavior of correlated fixed sized cell arrivals into a congested buffer. We derive the transient and time-averaged cell loss probabilities for several packet discarding policies, and we also derive the moments of the first passage time from a congested state to a threshold below which the buffer is considered in a non-congested state. We present numerical results for arrival processes having the same marginal distributions, but differing by autocorrelation coefficient only, thus isolating the effects of correlation on transient behavior. We conjecture how these results affect buffer congestion management procedures.     

Transient analysis including the low- and the medium-frequency ranges of engineering structures

This paper deals with a computational method for transient dynamic analysis which enables one to cover both the low- and medium-frequency ranges. This is a frequency approach in which the low-frequency part is obtained through a classical technique while the medium-frequency part is handled through the Variational Theory of Complex Rays (VTCR) initially introduced for vibrations. The aim of this paper is to show the capabilities of the method for transient analyses of complex engineering structures submitted to impact loadings.     

基于TOF测距的无线定位系统瞬时故障分析及处理

无线定位系统在实际应用中常因环境中的电磁干扰及无线传感器网络节点自身软硬件工作状态突变等因素的影响,出现定位不准确或定位数据遗漏等瞬时故障。针对瞬时故障导致的基于TOF测距的无线定位系统定位失效,分别从TOF测距和通信两方面提出故障解决方案。实验结果表明,该方案可以有效地控制瞬时故障导致的系统定位失效,提高了无线定位系统定位有效率和精确度。     

Transient thermal analysis of underground power cables using two dimensional finite element method

Microsystem Technologies - This paper introduces the finite element method is used for predicting the temperature distribution in underground cable, using arch-shaped finite elements with...     

Transient analysis of composite plates by radial basis functions in a pseudospectral framework

This paper presents a study of the linear transient response of composite plates using radial basis functions and collocation method in a pseudospectral framework. The first-order shear deformation plate theory is used to define a set of algebraic equations from the equations of motion and boundary conditions. The transient analysis is performed by a Newmark algorithm. In order to assess the quality of the present numerical method, an analytical solution was also developed. Numerical tests on square and rectangular cross-ply laminated plates demonstrate that the present method produces highly accurate displacements and stresses when compared with the available results.     

Transient analysis of the dynamic stress intensity factors using SGBEM for frequency-domain elastodynamics

In this paper, a two-dimensional symmetric-Galerkin boundary integral formulation for elastodynamic fracture analysis in the frequency domain is described. The numerical implementation is carried out with quadratic elements, allowing the use of an improved quarter-point element for accurately determining frequency responses of the dynamic stress intensity factors (DSIFs). To deal with singular and hypersingular integrals, the formulation is decomposed into two parts: the first part is identical to that for elastostatics while the second part contains at most logarithmic singularities. The treatment of the elastostatic singular and hypersingular singular integrals employs an exterior limit to the boundary, while the weakly singular integrals in the second part are handled by Gauss quadrature. Time histories (transient responses) of the DSIFs can be obtained in a post-processing step by applying the standard fast Fourier transform (FFT) and algorithm to the frequency responses of these DSIFs. Several test examples are presented for the calculation of the DSIFs due to two types of impact loading: Heaviside step loading and blast loading. The results suggest that the combination of the symmetric-Galerkin boundary element method and standard FFT algorithms in determining transient responses of the DSIFs is a robust and effective technique.