International Journal of Engineering
Volume:22 Issue: 3, Sep 2009

Placing column lap-splice in the locations of possible nonlinear deformation may adversely affect the structures response to strong ground motions. Localization of damage in splice zone may change the structural response and prevent the load redistribution and development of a uniform pattern of nonlinear excursions among the various members. Validated by existing laboratory experiments, this study presents a model that could be used to evaluate the behavior of lap-spliced columns. The proposed model is able to include the effect of the longitudinal bars arrangement; bars yield stress, and the amount and spacing of transverse bars. Comparison with existing experimental tests, show a good correlation between the model and experimental results. Finally, to obtain an estimation of the importance of the bar slip in lap splice on the structures response, fragility curves for life safety and collapse limit states are developed for an ordinary moment resisting frame of a one bay-ne story structure. Incremental dynamic analysis is used to derive the fragility curves. These fragility curves show that the bar slip have significant impact on the probability of exceeding collapse limit state, while its impact on the life safety limit state is not so significant.

Speech constitutes much of the communicated information; most other perceived audio signals do not carry nearly as much information. Indeed, much of the non-speech signals maybe classified as ‘noise’ in human communication. The process of separating conversational speech and noise is termed voice activity detection (VAD). This paper describes a new approach to VAD which is based on the Wavelet Packet Transform (WPT). Our algorithm utilizes the differences between spectral distribution of human speech (voice) and general noise. First, the algorithm performs wavelet transform on the signal resulting in its decomposition into subbands using coefficients of WPT, and then it detects the voice within the signal by comparing the subband energy of components between detail and approximation coefficients. Computer simulation results are given to illustrate the effectiveness of our new VAD algorithms.

This paper deals with the performance of a heat pipe solar collector. The solar collector consisted of an interconnected heat pipe so as to reduce the production cost by using an interconnected heat pipe because all the heat pipes can be evacuated, sealed and tested at once. Performance of a prototype of the heat pipe solar collector was experimentally examined, and the results were compared with those obtained through theoretical analysis. The results shown in this paper seem feasible.

This paper aims to describe a deterministic generation of extreme waves in a typical towing tank. Such a generation involves an input signal to be provided at the wave maker in such a way that at a certain position in the wave tank, say at a position of a tested object, a large amplitude wave emerges. For the purpose, we consider a model called a spatial-NLS describing the spatial propagation of a slowly varying envelope of a signal. Such model has an exact solution known as (spatial) Soliton on Finite Background (SFB) that is a non-linear extension of Benjamin-Feir instability. This spatial-SFB is characterized by wave focusing leading to almost time periodic extremes that appear between phase singularities. Although phase singularities and wave focusing has been the subject of number of studies, this spatial-SFB written in the field variables has many interesting properties among which are the existence of many critical values related to the modulation length of the monochromatic signal in the far fields. These properties will be used to in choosing parameters for a deterministic generation of extreme waves. Some example of such a generation in realistic variables will be displayed.

In the GA approach the parameters that influence its performance include population size, crossover rate and mutation rate. Genetic algorithms are suitable for traversing large search spaces since they can do this relatively fast and because the mutation operator diverts the method away from local optima, which will tend to become more common as the search space increases in size. GA’s are based in concept on natural genetic and evolutionary mechanisms working on populations of solutions in contrast to other search techniques that work on a single solution. An important aspect of GA’s is that although they do not require any prior knowledge or any space limitations such as smoothness, convexity or unimodality of the function to be optimized, they exhibit very good performance in most applications. The minimum cost flow problem is formulated as genetic algorithm and simulated annealing. This paper shows genetic algorithms and simulated annealing are much easier to implement for solving transportation problems compared with constructing mathematical programming formulations. Finally, a new empirical study for the effect of parameters on the rate of convergence of the GA and SA are demonstrated.

This paper presents a scheduling problem with unrelated parallel machines and sequencedependent setup times that minimizes the total weighted tardiness. A new branch-and-bound (B and B) algorithm is designed incorporating the lower and upper bounding schemes and several dominance properties. The lower and upper bounds are derived through an assignment problem and the composite dispatching rule (ATCS), respectively. We carry out computational experiments and the related results are reported

The stability of stratified Rivlin-Ericksen fluid in porous medium in the presence of suspended particles and magnetic field has been investigated. Upon application of normal mode technique, the dispersion relation was obtained. The important results obtained in this paper include the instability of non-oscillatory modes and the stability of oscillatory modes. Also, it was found that the system is stable for β < 0 and unstable for β > 0 under certain conditions.

In this work, rising of a single bubble in a quiescent liquid under microgravity condition was simulated. The related unsteady incompressible full Navier-Stokes equations were solved using a conventional finite difference method with a structured staggered grid. The interface was tracked explicitly by connected marker points via hybrid front capturing and tracking method. One field approximation was used, while one set of governing equations was only solved in the entire domain and different phases treated as one fluid with variable physical properties. The interfacial effects are accounted for by adding appropriate source terms to the governing equations. The results show that the bubble moves in a straight path under microgravity condition, compared to the zigzag motion of bubbles in the presence of gravity. Also, in the absence of gravity and temperature gradients, the hydrodynamic effect can still cause the upward motion of the bubble. This phenomenon was explicitly shown in our results.

In this article, an exact levy solution is presented for bending analysis of a functionally graded (FG) annular sector plate. The governing equilibrium equations are obtained based on the classical plate theory. Introducing an analytical method for the first time, the three coupled governing equilibrium equations are replaced by an independent equation in term of transverse deflection. This equation which is a forth-order partial differential equation is similar to the governing equilibrium equation of a homogeneous isotropic annular sector plate. Using an equivalent flexural rigidity, the solutions of FG annular sector plates can be easily extracted from equation of homogeneous annular plates. Finally, the effects of the exponents of the power functions, aspect ratio, inner to outer radius ratio and boundary conditions on the mechanical behavior of a functionally graded annular sector plate are discussed.