Chittagong University of Engineering & Technology

About: Chittagong University of Engineering & Technology is a education organization based out in Chittagong, Bangladesh. It is known for research contribution in the topics: Computer science & Renewable energy. The organization has 1200 authors who have published 1444 publications receiving 10418 citations. The organization is also known as: Engineering College, Chittagong & Bangladesh Institute of Technology, Chittagong.

Design and implementation of a RF controlled robotic environmental survey assistant system

Abstract: Survey operation to collect information about environmental parameters is an inevitable part in various cases. But manual data logging by human is dangerous in perilous places. This paper deals with design and implementation of a RF Controlled Robotic Environmental Survey Assistant System for remote survey operations, which can assist in remote data acquisition of environmental parameters like temperature, humidity and the presence and level of LPG gas in the air. Technically, two individual units make up the complete survey assistant system. First one is the wireless control unit for controlling and monitoring the survey process, whereas the second one is a remote controlled data collector robot unit which executes the survey process. The survey robot is equipped with sensor units required for measurement of temperature, humidity and combustible gas level as environmental parameters of the survey zone, ultrasonic sensor for obstacle detection in the path of the robot and GPS receiver for collecting information about position of the robot. A Radio Frequency (RF) Amplitude Shift Keying (ASK) transceiver channel enables the communication between the robot and control panel. The robot can be operated in two different modes. In autonomous mode, the robot travels a random path depending on obstacle avoidance technique and stores or collects and broadcasts live data stream to the control panel. Each time the robot is set to autonomous mode, after completion of a limited time survey operation, the robot comes back to it's starting position where autonomous mode was started. Obstacle sensor units installed in the robot helps it to detect and avoid obstacles in its path. The real-time data visualization is achieved on a Liquid Crystal Display (LCD) in the control panel and the mode of operation can be select from the control panel by operator.

New three phase bidirectional switch based AC voltage controller topologies

Abstract: A new family of three-phase AC voltage controllers has been presented in this paper. The proposed converters consisting of two three-phase modified bidirectional switches have supply and load side neutral connections either directly or indirectly which may be the requirements of three phase AC-AC switched mode voltage controllers in certain applications. Steady state analysis and simulation results are presented in this paper using the Boost topology as an example. Performance of the circuit has been found satisfactory with duty cycle variation. Because the proposed converters employ only two active devices, they can reduce cost and complexity with simple control and improve system reliability.

Effect of sintering temperature on structural and magnetic properties of Ni0.6Zn0.4Fe2O4 ferrite: synthesized from nanocrystalline powders

Abstract: The effect of sintering temperatures (Ts) on the structural and magnetic properties of Ni0.6Zn0.4Fe2O4(NZFO) ferrites synthesized by conventional double sintering method has been reported. The samples are sintered at 1200, 1250 and 1300 °C. The X-ray diffraction (XRD) analysis reveals the formation of a single phase cubic spinel structure of the sample. The magnetic parameters such as saturation magnetization, Ms; coercive field, Hc; remanent magnetization, Mr and Bohr magneton, µB are determined and compared with reported values. The obtained values are found to be 71.94 emu/gm and 1.2 Oe for Ms and Hc, respectively at Ts = 1300°C sample. Curie temperature (Tc) for various Ts has also been calculated. It is noteworthy that the sample with a very low Hc could be used in transformer core and inductor applications.

Power converters and control of wind energy conversion systems

Abstract: The rapid increase in global energy consumption and the impact of greenhouse gas emissions has accelerated the transition towards greener energy sources. The need for distributed generation employing renewable energy sources such as wind, solar and fuel cells has gained significant momentum. Advanced power electronic systems, affordable high performance devices, and smart energy management principles are deemed to be an integral part of renewable, green and efficient energy systems. This paper discuss the most emerging renewable energy source, wind energy, which by means of power electronics is changing from being a minor energy source to be acting as an important power source in the energy system and the standard power converter topologies from the simplest converters for starting up the turbine to advanced power converter topologies, where the whole power is flowing through the converter.

Efficiency calibration of $$\upgamma $$ γ -ray detector for extended sources

Abstract: Precise identification and quantification of radioisotope in a sample largely depend on the accuracy of the full-energy peak efficiency of the detector. It is generally observed that the efficiency for a given energy of point-like sources is not the same as the extended source. However, number of correction factors such as detector geometry, photon attenuation, coincidence-summing, etc. may reduce such a difference in efficiency regardless of sources, or they should be considered in the measurement of extended samples. In connection to this, the variation of absolute photopeak efficiency of a high-purity germanium (HPGe) detector with the distances from the surface of the detector as well as with the $$\upgamma $$ -ray energies were investigated using $$\upgamma $$ -ray standard point sources. We present a method to determine the loss of efficiencies in radioactivity measurement of the thin extended radioactive disc samples in comparison to point source.