Volume 2 Issue 1
Authors: Oleg Sytnik
Abstract: The method of detection and identification of a low Doppler target under conditions of intensive disturbances having fluctuating character is investigated in this article. The proposed algorithm for calculating the estimations of the target spatial position and the Doppler frequency translation of a signal reflected from the target is an optimum from the standpoint of the maximum of likelihood. The algorithm was based on the principle of the combined processing of signals from spaced sensors in order to obtain the optimum estimations of signal parameters. The analysis is carried out both in the spectral and in the time domains which makes it possible to extract a maximum amount of information about the object under investigation with disturbances of different character and level. The results of the algorithm modelling are presented; the characteristic features of its performance in actual practice are discussed.
Keywords: Targets Selection; Orthogonal Decomposition; Algorithm; Reflected Signal; Aantenna; Doppler’s Frequency Shift
Authors: K. B. Ladhane; S. P. Hajare; V. A. Sawant
Abstract: A mesh-free method is presented to analyze the infinite beam on elastic foundation. In the present analysis method of least-square (MLS) interpolation is used to construct shape functions based on a set of nodes arbitrarily distributed in the analysis domain. Discrete system equations are derived from the variation form of system equation. A FORTRAN program is developed and numerical examples of finite and infinite beams on elastic foundation are presented. The attempts have been made to present the convergence and the efficiency of the method.
Keywords: Mesh Free Method; Method of Least-square Interpolation; Beams on Elastic Foundation; Element Free Galerkin Method
Authors: Essam Zaneldin; Bilal El-Ariss
Abstract: Advanced computer programs used for structural analysis and design have become widely used; however, classical and easy-to-use tools, such as design charts and tables, are still preferable for students, who need simple tools instead of sophisticated and time-consuming programs. These tools help students electronically retrieve section properties-related information and use this information in the design of structural members. It is, therefore, clear that design charts, tables, and section properties should be made electronically available to engineering students. In this study, Microsoft Visual Basic, a widely-used and easy-to-use programming language, was used to develop an interactive framework that provides students with the ability to create powerful forms that can be used for different steel sections and their properties. The framework was developed to produce steel section properties provided in the AISC and CISC Manuals of Steel Construction and needed in the design charts. This paper describes how the framework was developed and presents some real-world examples to illustrate its ease-of-use and powerful capabilities over current practices. Comments and recommendations pertaining to future developments in the field are then presented in the conclusions.
Keywords: Visual Basic; Spreadsheets; Education; Structural Engineering
Authors: H. Y. MOK; M. C. WU
Abstract: The design of buildings and structural systems requires consideration of winds and gusts. Among the wind parameters, the gust factor, which reflects the degree of wind turbulence or gustiness, is one of the critical parameters widely employed in codes and standards for estimating the wind loading effect. Hong Kong, located at the coast of south China, has a sub-tropical climate with significant seasonal variation. Different weather systems characterize different seasons, resulting in a marked seasonal variation in wind speed and prevailing wind direction. Climatologically, high wind and gust conditions in summer are attributed to the passage of tropical cyclones while those in winter are attributed to intense winter monsoons. In addition to seasonal variation, the wind pattern in Hong Kong is complicated by the complex terrain and the densely distributed high-rise buildings constructed in the past few decades. This study analyses the wind data measured at different locations of the territory by a network of anemometers, the aim being to examine the characteristics of the gust factors in summer and winter in different regions as well as to determine the long-term trend, if any, of the gust factors.
Keywords: Gust Factor; Trend; Regional Variations; Seasonal Variations; Hong Kong
Authors: P.B.R. Dissanayake; P. Chun; M. Ohga; J.M.R.S. Appuhamy
Abstract: Major steel bridges are usually the crucial elements of the road and railway infrastructures. Very often they constitute a part of critical links between highly habited areas. As a consequence, their closure or traffic capacity reduction causes major inconveniences for the users and result in significant losses to the economy. Corrosion is one of the most important causes of deterioration of steel girder bridges which affects their long term mechanical performance, usability, and durability. Furthermore, some recent earthquakes demonstrated the potential seismic vulnerability of some types of steel bridges, and hence, it would be very important to understand the behaviour of existing steel bridges which are corroding for decades in future severe seismic events as well. Therefore, there is a need for evaluation procedures for an accurate prediction of the load carrying capacity and seismic resistance of bridge structures, in order to make rational decisions about repair, rehabilitation, and expected life-cycle costs. Therefore this paper investigates the effect of severe corrosion on remaining seismic strength capacities of existing steel bridge infrastructures through many finite element analyses and develops a simple, accurate, and reliable methodology which can be used for their maintenance management plan.
Keywords: Bridge Maintenance; Corrosion; Earthquakes; Seismic Resistance; Numerical Analysis