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A Discrete-Time Algorithm for the Resolution of the Nonlinear Riccati Matrix Differential Equation for the Optimal Control
Issue:
Volume 2, Issue 2, March 2014
Pages:
12-17
Received:
7 November 2013
Published:
10 March 2014
Abstract: The Riccati Matrix Differential Equation (RMDE) is an interesting equation in different fields of science and engineering practice. In fact, that the arithmetic solution for this matrix differential equation in the general case of varying-time matrices is very difficult to find. The literature offers the solution of this differential equation in the case of dependant constant matrices (i.e. invariant-time matrices). The present approach is an approximate discrete-time method for the resolution of the matrix differential equation of Riccati in the general case of varying-time (dependant of time) matrices; the method in fact, is a discrétisation of the exact matrix solution, that evaluates for any so small step of time, and which is function of the solution of the preceding step of time and the constitute equation matrices. The proposed algorithm is verified, for a controlled structure under Modified El-Centro earthquake by a comparison with the same uncontrolled structure, which constitutes by a two Degrees Of Freedom (2DOF) system. The results of this comparison offer good differences between the controlled and the uncontrolled systems.
Abstract: The Riccati Matrix Differential Equation (RMDE) is an interesting equation in different fields of science and engineering practice. In fact, that the arithmetic solution for this matrix differential equation in the general case of varying-time matrices is very difficult to find. The literature offers the solution of this differential equation in t...
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Performance of Damage Detection Methods used in Bridge Structures through Dynamic Tests in Steel Beams
Rolando Salgado,
Gustavo Ayala,
Paulo J. S. Cruz,
Sergio A. Zamora
Issue:
Volume 2, Issue 2, March 2014
Pages:
18-26
Received:
31 January 2014
Published:
20 March 2014
Abstract: In this document, the performance of damage detection methods used for the evaluation of bridge structures was determined. To do that, these methods were applied to the experimental dynamic parameters obtained from cracked steel I beams. Different damage scenarios were simulated in the steel I beams through saw-cuts perpendicular to the longitudinal axis of the beams. The damage detection methods were evaluated under different damage scenarios tried to represent fatigue damage in bridge structures. Ambient vibration tests, before and after damage, were performed on analyzed beams and the obtained dynamic parameters were used for the damage detection procedure. For all the evaluated scenarios, only the first three mode shapes were taken into account. Results indicated high possibility of damage detection when the severity of damage increase, damage is close to a measuring point and far away from an inflexion point and/or the boundary conditions. It was found that Level I methods (just detection) are not confidence to detect damage. On the other hand, level II methods (location) had good performance for the most severe damage scenarios. It was found out that Wavelet based methods are the best choice for their application to bridge structures.
Abstract: In this document, the performance of damage detection methods used for the evaluation of bridge structures was determined. To do that, these methods were applied to the experimental dynamic parameters obtained from cracked steel I beams. Different damage scenarios were simulated in the steel I beams through saw-cuts perpendicular to the longitudina...
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Analysis of Physicochemical Properties for Treatment of Dredged Deposit Soil
Youngshin Lee,
Sanghee Shin
Issue:
Volume 2, Issue 2, March 2014
Pages:
27-34
Received:
27 February 2014
Published:
20 March 2014
Abstract: This study was conducted to analyze the properties of deposit soil dredged from a reservoir which was processed for efficient treatment and management. Before starting this study, the physicochemical properties and the heavy metal content of the deposit soil were investigated to collect the fundamental data. In a treatment experiment proposed to use the deposit soil, the deposit soli was separated according to the particle diameter and only the cohesive soil having a diameter of 106 μm or smaller was used for plastic working after mixing it with a cross-linking agent. The dissolution experiment performed with the plastic worked deposit soil showed that the dissolution concentration was decreased as the plastic working temperature was increased. The dissolution concentration was drastically decreased especially in the 500oC to 1000oC interval of the plastic working temperature. For the future practical use, red clay was mixed with ceramic and a dissolution experiment and an experiment to calculate the saturated permeation coefficient were performed with the mixture. For the experiments, a module was prepared with the red clay to ceramic ratios of C-1 (5.3 L: red clay +ceramic=10:1), C-2 (5.3 L: red clay), and C-3 (2.65 L: ceramic, 2.65 L: red clay). Artificial sewage was injected to the module in which red clay and ceramic were mixed. The result showed that the pollutant dissolution concentration was higher when the dissolution time was longer. The pollutant dissolution concentration was in the order of C-1 > C-3 > C-2 with the C-1 as the highest. The saturated permeation coefficient showed a similar tendency with that of the pollutant dissolution concentration. The result showed that the initial pollutant dissolution concentration was low in C-2 in which only pure soil was included. As time passed, the pollutant dissolution concentration of C-1 and C-3 was decreased.
Abstract: This study was conducted to analyze the properties of deposit soil dredged from a reservoir which was processed for efficient treatment and management. Before starting this study, the physicochemical properties and the heavy metal content of the deposit soil were investigated to collect the fundamental data. In a treatment experiment proposed to us...
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Critical Factors Affecting Construction Labor Productivity in Egypt
Sherif M. Hafez,
Remon F. Aziz,
Enas S. Morgan,
Madeha M. Abdullah,
Eman K. Ahmed
Issue:
Volume 2, Issue 2, March 2014
Pages:
35-40
Received:
29 January 2014
Published:
30 March 2014
Abstract: The construction industry plays an important role in any developing country. This sector will promote the infrastructure required in socioeconomic development which also a major contributor to the overall economic growth. One of the main factors that had influence in the construction industry growth is productivity which mainly associated with the labor performance. Labor in construction industry could be defined as all workforces involve in the process that had to carry out to accomplish and to achieve goal. The labor productivity insufficiency will affect the performance of the overall project. The objective of this research is to identify and rank the relative importance of factors perceived to affect labor productivity on Egyptian construction projects. To achieve this objective, a statistically representative sample of contractors was invited to participate in a structured questionnaire survey, comprising 27 productivity factors, classified under the following four primary groups: (a) Technological; (b) Management; (c) Human/Labor; and (d) External. Among the factors explored, the subsequent ten are discerned to be the most significant in their effects on labor productivity: (1) Payment delay; (2) Skill of labor; (3) A shortage of experienced labor; (4) Lack of labor supervision; (5) Motivation of labor; (6) Working overtime, (7) Construction managers lack of leadership, (8) High humidity, (9) Clarity of technical specification, (10) High/low temperature. The results obtained fill a gap in knowledge of factors affecting labor productivity in Egypt, which can be used by industry practitioners to develop a wider and deeper perspective of the factors influencing the efficiency of operatives, and provide guidance to construction managers for efficient utilization of the labor force, hence assist in achieving a reasonable level of competitiveness and cost effective operation.
Abstract: The construction industry plays an important role in any developing country. This sector will promote the infrastructure required in socioeconomic development which also a major contributor to the overall economic growth. One of the main factors that had influence in the construction industry growth is productivity which mainly associated with the ...
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An Overview on the Seismic Design of Braced Frames
Muhammad Tayyab Naqash,
Khalid Mahmood,
Salim Khoso
Issue:
Volume 2, Issue 2, March 2014
Pages:
41-47
Received:
10 February 2014
Published:
30 March 2014
Abstract: Seismic design of steel braced frames in the modern building codes follow the capacity design approach where some of the members are obliged to dissipate energy whereas others are taken care to be protected. In this paper the seismic design methodologies used by European and American approaches for Concentric Cross Braced Frames (CCBF) and Eccentric Braced Frames (EBF) are highlighted. Synoptic tables for the design of such frames of the most advance seismic codes i.e., Eurocode 8 and the seismic provisions of American Institute of Steel Construction (AISC) are provided. Emphasizes are made on the provisions of Eurocode 8 both for CCBF and EBF. Finally, a general conclusion is drawn when dealing with CCBF and EBF
Abstract: Seismic design of steel braced frames in the modern building codes follow the capacity design approach where some of the members are obliged to dissipate energy whereas others are taken care to be protected. In this paper the seismic design methodologies used by European and American approaches for Concentric Cross Braced Frames (CCBF) and Eccentri...
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Development of Rainfall Recharge Model for Natural Groundwater Recharge Estimation in Godagari Upazila of Rajshahi District, Bangladesh
Md. Nurul Islam,
Anupam Chowdhury,
Kazi Moinul Islam,
Mohammed Ziaur Rahaman
Issue:
Volume 2, Issue 2, March 2014
Pages:
48-52
Received:
3 March 2014
Published:
30 March 2014
Abstract: Estimation and forecast of groundwater recharge and capacity of aquifer are essential issues in effective groundwater resource management in Bangladesh. Godagari Upazilla is located in High Barind Tract situated in the northwestern part of Bangladesh. A typical dry climate with comparatively high temperature prevails in this Barind area. It is particularly significant in regions with large demands for groundwater supplies to meet irrigation needs, where such resources are the key to economic growth. However, the rate of aquifer recharge is one of the most complicated factors to assess in the evaluation of groundwater resources. Assessment of recharge, by whatever method, is normally subject to large uncertainties and errors. In this paper, an attempt has been taken to develop a rainfall recharge model by non-linear regression technique to determine groundwater recharge using only annual rainfall data in Godagari Upazilla based upon groundwater balance study carried out for a number of years. It was also proven that the developed model provided an accurate estimation for similar projects
Abstract: Estimation and forecast of groundwater recharge and capacity of aquifer are essential issues in effective groundwater resource management in Bangladesh. Godagari Upazilla is located in High Barind Tract situated in the northwestern part of Bangladesh. A typical dry climate with comparatively high temperature prevails in this Barind area. It is part...
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Investigation of Ground Water Table in the South-East (Chittagong) Part of Bangladesh
Md. Abdul Hamid Mirdad,
Swapan Kumar Palit
Issue:
Volume 2, Issue 2, March 2014
Pages:
53-59
Received:
5 March 2014
Published:
30 March 2014
Abstract: Ground water forms the major portion of earth’s fresh water source and it is almost safe to drink. Depletion of ground water table due to continuous pumping causing scarcity of water in the city area of Bangladesh. So information about ground water table is required for future recommendation of ground water supply to general people. For the investigation purpose, depth of water table has been determined in three seasons with respect to mean sea level. Among 41 wards of Chittagong City, 18 wards have been selected for this purpose where depth of water table is measured from the shallow tube well. The present investigation includes field investigation for locating of tube well in Chittagong City Corporation area with the aim of measuring water level from ground surface. Seasonal variation of the water level has also been determined with respect to man sea level. Water collected from the well has been evaluated in the laboratory for determining quality of water. From the investigation, it has been established that, water table with respect to mean sea level is different at different wards. Seasonal variation has been observed due to lowering of water table and it has been found that water table is minimum at drought season
Abstract: Ground water forms the major portion of earth’s fresh water source and it is almost safe to drink. Depletion of ground water table due to continuous pumping causing scarcity of water in the city area of Bangladesh. So information about ground water table is required for future recommendation of ground water supply to general people. For the investi...
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