http://dspace.mist.ac.bd:8080/xmlui/handle/123456789/568 Volume 8, Number 2, December 2020 2026-04-26T00:20:29Z http://dspace.mist.ac.bd:8080/xmlui/handle/123456789/576 Modeling and Control Simulation of a Robotic Chair-Arm: Protection against COVID-19 in Rehabilitation Exercise Akhtaruzzaman, M.; Shafie, Amir A.; Khan, Md Raisuddin; Rahman, Md Mozasser In the field of rehabilitation, lower-limbs therapeutic exercise has become a challenging job for medical professionals in COVID-19 pandemic. Providing manual therapy to lower limbs is not an easy task and, in most cases, it involves multiple persons. Moreover, it is a monotonous job, and the service providers need to be in close contact with the patient thereby creating the risk of infection. In this circumstance, robot-assisted rehabilitation exercise for lower limbs offers a risk-free solution. This paper presents dynamic modeling and control simulation of One Degree of Freedom robotic chair-arm (robotic arm attached with a special chair). The control structure is designed with two compensators for position and velocity control. The simulation results show that the proposed system has a good potential in providing automatic rehabilitation therapy for lower limbs, especially for knee joint range of motion exercise. The results also indicate faster responses with settling time less than 0.04 second and steady-state error below 0.05. The findings show that a robotic chair arm can be used for providing automatic therapy to patients in situations like COVID-19 pandemic. 2020-12-16T00:00:00Z http://dspace.mist.ac.bd:8080/xmlui/handle/123456789/575 Tensile Strength Study of Stainless-Steel using Weibull Distribution Bhuiyan, Md Shahnewaz; Anzum, Tanzida; Hasan, Forhad-Ul-; Rahman, M. Azizur In the present study, the distribution pattern of the ultimate tensile strength of 304-grade stainless steel was investigated using a two-parameter Weibull distribution function. During tensile testing, it was observed that the ultimate tensile strength varied from specimen to specimen (ranges from 878 to 1006 MPa). The results have revealed that the distribution pattern of the tensile strength can be described by the two-parameter Weibull distribution equation. Moreover, the fracture statistics of the stainless steel were examined by plotting the survival probability of the specimen against the applied stress to the specimen. It has been observed that the relationship between the survival probability and the applied stresses can be described by the Weibull model. It also provides design engineers with a tool that will help them to present the necessary mechanical properties with confidence. 2020-12-16T00:00:00Z http://dspace.mist.ac.bd:8080/xmlui/handle/123456789/574 Corrosion Behavior of Copper Based Heat Exchanger Tube in Waters of Bangladesh Region at Varied Temperature and Flow Velocity Rahman, M. Muzibur; Ahmed, S. Reaz Heat exchangers used in the ships are mostly of water-cooled shell and tube type, whose tube stacks are made of copper-based materials due to the requirement of high corrosion resistance and high thermal conductivity. Even though, the copper made heat exchanger tubes do fail on board ships because of corrosion. More point of contention arises when it is manufactured by companies that have limited supporting data and documentations. In this context, the present paper investigates the corrosion behavior of copper tubes of heat exchanger to assess the life span of the tube stack for on-board applications. A series of experiments have been undertaken to investigate the corrosion rates of copper tubes in sea water and river water with flow velocity of 1.0 𝑚𝑠 1.5 𝑚� and 2.0 𝑚� for the tube side entry temperature of 20°𝐶 The same experiments have been repeated for the shell side temperatures of 20°𝐶 40°𝐶 60° and 80°𝐶 The investigations have revealed that the corrosion in sea water is about three times higher than that of river water. The increases in temperature and flow velocity have increased the rate of corrosion to a significant level contributing to shorten the life span. 2020-12-16T00:00:00Z http://dspace.mist.ac.bd:8080/xmlui/handle/123456789/573 Experimental Analysis on Safety System of a Simulated Small Scale Pressurized Water Reactor System with Intelligent Control Islam, Md. Shakerul; Hossain, Altab; Mursed, Khalid; Chowdhury, Rafi Alam Reactors are widely used in the nuclear power plant due to the rapid demand for electricity by reducing the greenhouse effect. However, the effectiveness of the nuclear reactor depends on an adequate safety system. Hence, temperature and heat transfer are two critical parameters for any reactor in operation for which intelligent temperature control with an integrated safety system is essential. Therefore, the present study has emphasized the development of a simulated small-scale water-based reactor with intelligent control and safety system and examined through the analysis of thermal-hydraulic parameters. Radial heat transfer of an electric rod used as fuel in the primary circuit has been analyzed by taking sensor reading in various positions of the core. The developed system is self-controlled with all possible active and passive safety systems. Consecutively, the prototype has also been designed including manual adjustment to ensure a fail-safe environment. The system is capable to operate at temperatures between 80°𝐶 and 120°𝐶, although the design can withstand up to 200°𝐶. The data of the experiment are taken under the pressure of 200 𝑘𝑃𝑎 at 120°𝐶 temperature. Results show that heat output of 2116.09 𝑘𝐽 has been obtained from the system against heat input of 2514.80 𝑘𝐽, which gives an efficiency around 16% of the developed system. 2020-12-16T00:00:00Z