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1 – 10 of over 2000Sk Abdul Kaium, Sayed Abul Hossain and Jafar Sadak Ali
The purpose of this paper is to highlight that the need for improved system identification methods within the domain of modal analysis increases under the impulse of the…
Abstract
Purpose
The purpose of this paper is to highlight that the need for improved system identification methods within the domain of modal analysis increases under the impulse of the broadening field of applications, e.g., damage detection and vibro-acoustics, and the increased complexity of today’s structures. Although significant research efforts during the last two decades have resulted in an extensive number of parametric identification algorithms, most of them are certainly not directly applicable for modal parameter extraction. So, based on this, the aim of the present work is to develop a technique for modal parameter extraction from the measured signal.
Design/methodology/approach
A survey and classification of the different modal analysis methods are made; however, the focus of this thesis is placed on modal parameter extraction from measured time signal. Some of the methods are examined in detail, including both single-degree-of-freedom and multi-degree-of-freedom approaches using single and global frequency-response analysis concepts. The theory behind each of these various analysis methods is presented in depth, together with the development of computer programs, theoretical and experimental examples and discussion, in order to evaluate the capabilities of those methods. The problem of identifying properties of structures that possess close modes is treated in particular detail, as this is a difficult situation to handle and yet a very common one in many structures. It is essential to obtain a good model for the behavior of the structure in order to pursue various applications of experimental modal analysis (EMA), namely: updating of finite element models, structural modification, subsystem-coupling and calculation of real modes from complex modes, to name a few. This last topic is particularly important for the validation of finite element models, and for this reason, a number of different methods to calculate real modes from complex modes are presented and discussed in this paper.
Findings
In this paper, Modal parameters like mode shapes and natural frequencies are extracted using an FFT analyzer and with the help of ARTeMiS, and subsequently, an algorithm has been developed based on frequency domain decomposition (FDD) technique to check the accuracy of the results as obtained from ARTeMiS. It is observed that the frequency domain-based algorithm shows good agreement with the extracted results. Hence the following conclusion may be drawn: among several frequency domain-based algorithms for modal parameter extraction, the FDD technique is more reliable and it shows a very good agreement with the experimental results.
Research limitations/implications
In the case of extraction techniques using measured data in the frequency domain, it is reported that the model using derivatives of modal parameters performed better in many situations. Lack of accurate and repeatable dynamic response measurements on complex structures in a real-life situation is a challenging problem to analyze exact modal parameters.
Practical implications
During the last two decades, there has been a growing interest in the domain of modal analysis. Evolved from a simple technique for troubleshooting, modal analysis has become an established technique to analyze the dynamical behavior of complex mechanical structures. Important examples are found in the automotive (cars, trucks, motorcycles), railway, maritime, aerospace (aircrafts, satellites, space shuttle), civil (bridges, buildings, offshore platforms) and heavy equipment industry.
Social implications
Presently structural health monitoring has become a significantly important issue in the area of structural engineering particularly in the context of safety and future usefulness of a structure. A lot of research is being carried out in this area incorporating the modern sophisticated instrumentations and efficient numerical techniques. The dynamic approach is mostly employed to detect structural damage, due to its inherent advantage of having global and location-independent responses. EMA has been attempted by many researchers in a controlled laboratory environment. However, measuring input excitation force(s) seems to be very expensive and difficult for the health assessment of an existing real-life structure. So Ambient Vibration Analysis is a good alternative to overcome those difficulties associated with the measurement of input excitation force.
Originality/value
Three single bay two storey frame structure has been chosen for the experiment. The frame has been divided into six small elements. An algorithm has been developed to determine the natural frequency of those frame structures of which one is undamaged and the rest two damages in single element and double element, respectively. The experimental results from ARTeMIS and from developed algorithm have been compared to verify the effectiveness of the developed algorithm. Modal parameters like mode shapes and natural frequencies are extracted using an FFT analyzer and with the help of ARTeMiS, and subsequently, an algorithm has been programmed in MATLAB based on the FDD technique to check the accuracy of the results as obtained from ARTeMiS. Using singular value decomposition, the power Spectral density function matrix is decomposed using the MATLAB program. It is observed that the frequency domain-based algorithm shows good consistency with the extracted results.
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This chapter is derived from the result of research conducted by Firman Menne, Lanita Winata and Mohammad Hossain. The emergence of Islamic Financial Institutions (IFIs) is…
Abstract
Purpose
This chapter is derived from the result of research conducted by Firman Menne, Lanita Winata and Mohammad Hossain. The emergence of Islamic Financial Institutions (IFIs) is expected to provide enormous benefits for the Muslim community in Indonesia such as the availability of IFIs based on Sharia law and the implementation of Islamic value in the community. Like Corporate Social Responsibility (CSR) practices in all business organizations, the IFI’s CSR becomes one of the important factors in improving organizational performance. The implementation of CSR in IFIs is unique as it is based on Sharia law. Zakat and Qardh are the unique IFI CSR practices. There are many studies which have investigated the relationship of Zakat and Qardh on organizational performance in Arabic and Muslim countries. In Muslim countries, Islamic laws, including providing Zakat and Qardh, are practices of every business organization. As Indonesia is not a Muslim country, Zakat and Qardh are only required for IFIs as part of CSR practices. This study aims to analyse the influence of CSR practices on the financial performances of IFIs in Indonesia using gender as a control variable.
Methodology/approach
The samples of this research were taken from the annual reports of nine Islamic banks for the period of 2010–2014. Regression method was used to analyse and test hypotheses.
Findings
The results of this research indicate that the relationship between CSR practices and financial performance is significant, the value of R is 0.737, and R square is 0.543.
Practical implications
This means that the implementation of CSR practices (Zakat and Qardh) improves organizational financial performances of IFIs in Indonesia.
Originality/value
This study also has a limitation as it only focuses on Zakat and Qardh; thus in the future, it is necessary to advance the variable of CSR practices on the real social and environmental practices such as environmental improvement, increasing the quality of human resources, involvement in any jobs or reducing unemployment and any other activities.
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Sayed Hossain, Nik Hashim Nik Mustapha and Lee Tak Chen
Farming in Bangladesh is confronted with various types of uncertainties, which contribute to farmers’ income volatility over the years. As a result, cereal, mainly rice, which is…
Abstract
Farming in Bangladesh is confronted with various types of uncertainties, which contribute to farmers’ income volatility over the years. As a result, cereal, mainly rice, which is a less riskier crop remained dominantly planted in the current farm plan. But the return generated from rice cultivation has not been able to improve the livelihood of the poor, as rice profitability is low compared to some profitable but risky crops like jute and vegetables. To investigate the behavioral pattern of the farmers towards risk, Dhaka division, largely known as central region of Bangladesh, is selected. The prevailing farm plan of Dhaka division is compared with the efficient one at the current level of expected return in order to check whether the current farm plan is risky or otherwise. Quadratic and MOTAD as well as linear programming techniques have been employed for the analysis. The result of the study reveals that the prevailing farm plan in Dhaka division is risky compared to the efficient plan. Since the current return level is low, the study has recommended that more jute and vegetables should be planted to achieve higher remuneration.
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Sayed Hossain and Ming‐Yu Cheng
Since independence in 1971, Bangladesh has undergone episodes of change and has recorded considerable economic achievements. In this study, a standard regression model is used to…
Abstract
Since independence in 1971, Bangladesh has undergone episodes of change and has recorded considerable economic achievements. In this study, a standard regression model is used to identify factors that significantly contribute to economic growth in Bangladesh. The factors under consideration are private and public investment, public and private consumption, export and import. All factors are found to have a significant positive relationship with GDP at 5 percent of significance level except for public investment. The result implies that privatisation process needs to be catered with greater attention for accelerating GDP growth. Import is found to be significant but with a negative relationship with GDP. The result indicates that with the increased in import, the GDP will decline further. As a matter of fact, more than 60 percent of the imported items are for consumption purposes which is not likely to contribute much to GDP growth. From the empirical estimation, it is suggested that prudence planning should be taken to enhance private investment, export, private and public consumption for a better living in the country.
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Adnan Aldholay, Osama Isaac, Zaini Abdullah, Rasheed Abdulsalam and Ahmed Hamoud Al-Shibami
While many researchers have investigated the adoption and usage of online learning in different settings, one area that has yet to be examined thoroughly, particularly in the…
Abstract
Purpose
While many researchers have investigated the adoption and usage of online learning in different settings, one area that has yet to be examined thoroughly, particularly in the context of online learning in Yemen, is the self-efficacy role. The purpose of this paper is to extend the Delone and McLean information system success model by incorporating a self-efficacy construct as an antecedent to user satisfaction and actual usage to predict student performance.
Design/methodology/approach
Questionnaire survey method was used to collect primary data from 448 students in nine public universities in Yemen. The six constructs in the proposed model were measured using existing scales. The data analysed using confirmatory factor analysis and structural equation modelling via AMOS.
Findings
Three main results were revealed, namely that overall quality (system, information and service quality) and self-efficacy have a positive impact on user satisfaction and actual usage; that actual usage significantly predicts user satisfaction; and that both user satisfaction and actual usage have a positive impact on student performance.
Research limitations/implications
First as the study population were students from nine public universities, it excluded academics and administrative staff. Second, the study depends on self-reported measures to test the proposed research model. This is because getting objective data about the performance was not probable due to the issue of privacy.
Practical implications
The findings of this study can be a guideline for Yemeni higher education institutions to develop efficient and effective plans to improve the performance of education institutions, and train and develop student ability to use online learning. Additionally, it highlights the areas that university management needs to concentrate on, namely information systems (IS) tools that will contribute to higher student enrolment, address the lack of infrastructure and improve the quality of education outcomes, things which represent Yemen’s main challenges in the higher education sector.
Originality/value
This paper adds to the existing literature of IS by combining overall quality, self-efficacy, actual usage and user satisfaction to predict performance impact of online learning among students in nine public universities in Yemen. Furthermore, the predictive power of the proposed model has a higher ability to explain and predict performance impact compared to those obtained from some of the previous studies.
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