Repairing and commissioning of an AC motor speed controller for a centrifugal pump

A centrifugal pump was installed in 1984 in the Fluid Mechanics Laboratory of Mechanical Engineering Department of Rajshahi University of Engineering & Technology. The motor of the centrifugal pump was dc motor and was not working. It could not be commissioned for a long time because of the damaged speed controller. The main shaft (rotor) was also jammed. In this project work, the dc motor was tried to repair. But it could not be run because the specification of the motor and the operating manual was not available. To complete the project successfully, the dc motor was replaced by an ac induction motor. After replacing the motor, the speed of the new motor was controlled by a variable frequency drive (VFD). Using this device, the speed was controlled from 600 rpm to 3000 rpm smoothly. After the replacement, the testing of the centrifugal pump was successfully performed and the motor was controlled in various speeds. Experiment on the performance test of the centrifugal pump was carried out satisfactorily running the pump in various speeds operated by the VFD

Applications of the homotopy perturbation method for some linear and non-linear partial differential equations

In this study, some linear PDEs and nonlinear PDEs are investigated using the homotopy perturbation method (HPM). The primary objective of this research is to employ the HPM as a tool for investigating a range of PDEs and extracting their analytical solutions. To clarify the practicality and efficacy of this method, we present illustrative examples of linear PDEs encompassing the classical heat, wave, and Laplace equations. Subsequently, a comparative analysis is performed, contrasting the outcomes derived from the HPM with established accurate solutions. Through this comparative approach, we aim to provide a comprehensive understanding of the HPM's applicability, robustness, and precision in solving a spectrum of PDEs. Our study contributes to the broader exploration of innovative mathematical techniques for tackling complex PDEs, while also shedding light on the potential advantages and limitations of the homotopy perturbation method in practical applications

Internationalization Process of Educational Consultancy Firms in Bangladesh: An Evaluation

The article focuses on the internationalization process of the educational consultancy firms based in Bangladesh, and on the strategies and methods they use. The major aim of this research was to gain a better understanding of the process by comparing and analyzing three main internationalization process theories: the Uppsala Model, Network Theory and International Entrepreneurship Theory. An essential part of this study consists of gathering empirical data from thirty educational consultancy firms in Bangladesh which have already been internationalized. The findings show the application and usefulness of the three theories to these firms. The findings also indicate that the selected firms used a combination of variables from mostly two theories: Network Theory and International Entrepreneurship Theory and that the much criticized Uppsala Model is quite insignificant in describing the internationalization process behavior of the firms in this industry. Keywords: The Uppsala Internationalization Process Model, Network Theory, International Entrepreneurship Theory, Educational Consultancy Firms

Ethno-sectarian division and the predicaments of national integration in plural societies: a study of Nigeria and Iraq

Objective: The purpose of this paper is to examine the problem of sectarianism in Nigeria and Iraq, as both countries provide typical examples of ethno-sectarian divided societies characterized by huge contrasts in social norms and religious values among the citizens. Methodology: Adopting content analysis, the current paper argues that ethno-sectarianism negatively affects political process in both countries which invariably undermines their effort toward national integration.The paper seeks to answer the following question: will restructuring the Nigerian and Iraqi federal relations contribute to resolving sectarian tensions? First, the paper examines the sources of sectarianism in both countries.The paper therefore examines how ethno-sectarianism shaped and molds the polity of both countries, where ethnic and religious values play major role in determining citizen’s reaction to political phenomenon Results: Coordination mechanisms such as framework legislation and dispute resolution committees are also necessary to ensure that the transition to viable federalism occurs with minimal encumbrance.To respect the complex and diverse identities of nations, safeguards need to be established to protect the rights of sub-federal nations.For example, the political future of Iraq and Nigeria is not a return to failed approaches of division, but rather the construction of a viable modern federal state that promotes unity, political compromise, and consensus building.Implication: This paper therefore posits that there is a need for deep mental changes and social adjustment among the citizens of both countries where attributes such as tolerance, dignity of human persons and above all patriotism must be re-defined and this requires collaboration between political leaders, community leaders and religious bodies as the problem is societal bound

Smart Grid Surveillance With Unmanned Aerial Vehicle (UAV) Using K-Resiliency Modeling

Smart grid being a widely distributed engineering system may run through deep forests to long rivers, and over the cities as well. Physical damage to the power line from natural calamities or, cyber attacks by malicious people on the control system will hamper the functional integrity of the power grid. To ensure the usual operational flow, the control center needs to take immediate steps caused by these phenomena. Hence, inspection of the power line provides a means for the smart grid surveillance. Since any physical damage to the power network can be occurred in hardly reachable remote areas, understanding the amount of impairment will be time-consuming. Autonomous systems like Unmanned Aerial Vehicles (UAV), instead of the traditional human patrol, are one way to enable regular monitoring of the safety critical situations. The critical lines will be monitored by a fleet of UAVs to ensure a resilient surveillance system. In this work, we present a formal model for UAV surveillance resiliency over the power lines with a set of k UAVs from the whole set. The proposed approach at first considers the n-1 contingency analysis using actual system data, and state estimation procedures. By using linear sensitivity factors, we find the critical transmission lines in the smart grid and in accordance with that, placements and communication topology of the UAVs are done. Then, we evaluate k-resiliency for the UAV surveillance to cover all the critical lines satisfying the circumstances in case of k failure in the fleet of UAVs

The role of expert evidence in medical negligence litigation in Malaysia

The courts are continuing to allow greater participation in the justice system by experts. Expert evidence is admissible in court whenever there are matters or issues which require their expertise in terms of observation, analysis, description and resolution.In medical negligence litigation, the ‘Bolam’ test is cited as the starting point.The test requires doctors to conform to a ‘responsible’ body of medical opinion. However, it has failed to define what a ‘responsible’ body of medical opinion is.The article aims to examine the role of expert evidence in medical negligence litigation cases. The scope of this article is limited to expert evidence in medical negligence litigation in Malaysia in the context of the standard of care required from doctors in the course of treatment, diagnosis and provision of information to their patients.The methodology is a legal, library-based research focusing mainly on primary and secondary sources.The findings indicate a need for reforms such as improving the quality of medical expert witness testimony by strengthening the qualifications for serving as a medical expert and providing more specific guidelines that govern the conduct of physicians throughout the legal process

Comparison of liver function status between home treated and hospital treated SARS-CoV-2 survivors

Background: SARS-CoV-2 has emerged as one of the greatest challenges faced by the world. There is association of liver injury with SARS-CoV-2 infection indicated by abnormal ALT levels accompanied by altered bilirubin level in blood. The aim of the study was to evaluate the quantitative difference of serum ALT and bilirubin level in home and hospital treated patients.Methods: A cross-sectional study was conducted in the Department of Biochemistry and Molecular Biology, Bangabandhu Sheikh Mujib Medical University, from July 2020 to June 2021. After infection most of the patients with mild symptoms were treated at home but patients with difficulty in breathing and various complications were treated at the hospital. Due to SARS-CoV-2 infection certain derangement of liver enzymes were noticed.Results: This study was planned to evaluate the changes of liver enzymes (ALT) and serum bilirubin after the recovery of SARS-CoV-2 infected patients. The aim of the study was to compare the derangement of serum bilirubin and ALT in home and hospital treated patients.Conclusions: There was no significant difference regarding liver function between these two groups

Biopesticidal Management of Pulse Beetle (Callosobruchus Chinensis L) in Chickpea Seeds

The pesticidal efficacy of four locally available leaves of botanicals like neem (Azadirachta indica), datura (Datura stramonium),  marigold (Tagetes erecta) and garlic (Allium sativum L.) tablet powders was assessed on pulse bettle (Callosobruchus chinensis L) through adult mortality and emergence, oviposition performance, seed damage, weight loss and germination  of chickpea (Cicer arietinum). The above test biopesticides were tested at three different rates (0.5 g, 1.0 g and 1.50 g powder/kg of chickpea seeds). All the tested powder showed significant effect on the above parameters. The highest adult mortality was recorded when chickpea seeds were treated with datura leaf powder at 1.50 g/kg, whereas marigold showed the least effect on adult mortality. The powders used in the experiment effectively controlled oviposition and adult emergence of pulse beetle. The lowest number of adult emergence was obtained from chickpea seeds treated with datura leaf powder at 1.50 g/kg. The highest weight loss was observed in control seeds followed by marigold leaf powder 0.5 g/kg gram seeds. Datura leaf powder treated seeds showed the lowest seed weight loss followed by neem, garlic and marigold. Plant powders had profound effect on seed germination. The highest germination was observed in treated seed with datura leaf powder at 1.50 g/kg and the lowest germination in control seed followed by marigold leaf powder at 1.5 g/kg treated seeds. The pesticidal effect on oviposition, adult mortality, adult emergence, and seed weight loss was directly proportional to leaf powder rates