Md. Ashraful Hoque

Cooperative communication in wireless sensor network using low density parity check codes

Energy efficient data transmission is one of the key factors for energy constraint wireless sensor network (WSN). Cooperative communication explores the energy efficient wireless communication schemes between multiple sensors and data gathering node (DGN). In this paper, an energy efficient cooperative technique is proposed considering low density parity check (LDPC) codes. The result shows that the proposed cooperative communication outperforms SISO transmission when the error correction code is considered. Bit error rate (BER) analysis is also performed. In this work, it shows that the lower encoding rate offers better error characteristics for same signal to noise ratio (SNR)

An overview of smart grid technology in Bangladesh: Development and opportunities

Generally smart grid is a modern technology of power system which can convert the whole power system in to digital format. In brief, a smart grid is the use of sensors, communications, computational ability and control in some form to enhance the overall functionality of the electric power delivery system. A system becomes smart by sensing, communicating, applying intelligence, exercising control and through feedback. For an ideal power system, this permits several functions which can optimize in the combination of the use of bulk generation and storage, transmission, distribution, and consumers. It can fulfill the goal which can ensure reliability and optimization of the use of Energy. It will also keep the environment free from pollution, save the assets, minimize the cost, easy operation against all hazards, maximum possibility to keep out from danger, provides power quality for 21st century needs. The focus of this paper is to familiarize with smart grid perspective to Bangladesh. The conception of smart grid is almost new is Bangladesh. The whole power system network in Bangladesh is very elaborate and complex but primitive. To reduce this complexity and improve the performance of the system, smart grid can be a better solution. Load-shedding is a common phenomenon in Bangladesh. It can be solved by smart grid technology. As it can automatically detect, calculate and distribute electricity as per load requirements, it reduces the system loss and at the same time a certain amount of electricity from the grid would always be available at each consumer side even at the time of load shedding. Bangladesh can be greatly benefited by using this technology. The main objective of this paper is to discuss the necessity of smart grid for the perspective of Bangladesh which may be an effective solution to overcome the recent power crisis.

Numerical analysis of CdTe thin film solar cells with CdS:O window layer and ZnO buffer layer

This paper has numerically evaluated the performance of a proposed modified structure of thin film solar cell based on CdS/CdTe. In this proposed cell, conventional CdTe layer has been used as absorber, but a new back contact Ni has been used along with newly introduced 100 nm thick ZnO layer to increase the performance of the conventional solar cell. The feasibility of ultra-thin CdTe absorber layer with newly added CdS:O layer instead of conventional CdS layer has also been examined. It has been found that the proposed ultra-thin cell had conversion efficiency of 21.57% (with Voc = 0.89 V, Jsc = 28.32 mA/cm2, and FF = 85.78%). These outcomes have proved the feasibility of the proposed modified CdTe solar cell showing approximately 4.3% more efficiency than the conventional one

An analysis of efficiency variation in an Al0.7Ga0.3As/Al0.48In0.52As heterojunction solar cell with change in device parameters using adept 1D software

In this paper, efficiency variation with change in device parameters (layer thickness and doping concentration) has been investigated in an Al0.7Ga0.3As/Al0.48In0.52As heterojunction solar cell using Adept 1D simulation software. The device uses a n-type Al0.7Ga0.3As top layer (Emitter), a p-type Al0.48In0.52As middle layer (Base), and a p-type Ga0.67In0.33As bottom layer, which, under high doping, acts as a passivating (BSF) layer. Germanium (Ge) substrate (p-doped) is used for the structure. Variation in efficiency is plotted against a particular changing parameter, keeping every other parameter fixed at some default value. After analysing the variation curves, two optimized designs have been proposed, which yield 19.57% and 20.56% efficiency, respectively.

Nominal and Detailed LTE Radio Network Planning considering Future Deployment in Dhaka City

Long Term Evolution (LTE) is the next major step in mobile radio communications and is introduced in 3rd Generation Partnership Project (3GPP) Release 8. It is the last step toward the 4th generation (4G) of radio technologies designed to increase the capacity and speed of mobile telephone networks. With industrial attachment very few radio planning works of LTE are going on. But because of certain commercial issues those works aren‟t widely available. Radio network planning is a very vital step for wireless communication technology. As standardization work of LTE is approaching the end line, it is high time to go for efficient radio network planning guideline for LTE. In LTE just like other cellular technologies, initial planning is normally guided by various industries and vendors at their own discretion. They aren‟t likely to disclose their advancements and findings. That makes the job even more challenging. As a result, going on with LTE radio network planning perspective is a well-chosen challenge and a certain hot topic in the current research arena. In this work, a detailed LTE radio network planning procedure has been elaborated which concentrates on nominal and detailed planning considering possible network implementation in the densely populated South-Asian city-Dhaka.

Spectral analysis of human sleep EEG signal

As is well known, analyzing the frequency components of the EEG is important for the sleeping. There are many methods of studies to analyze the EEG frequency data for recognizing the sleep and its quality, and so on. However, there is no established method for the analysis of the sleeping EEG. For this reason we went for a very useful tool in signal analysis – spectral analysis. An analysis of the variation in magnitude of EEG signals in various frequency bands of sleeping persons was carried out. All the defined bands of the EEG signal of three healthy persons were closely analyzed. The EEG data were collected from internet available for public free download. The aim of the paper is to find out the exact frequency band by analyzing which we can say that whether a person is sleeping or not. Matlab along with “eeglab” toolbox was used for the necessary analysis. It is observed that DeltaBand provides us sufficient information for concluding about sleep.

Impact of user mobility on the performance of downlink resource scheduling in Heterogeneous LTE cellular networks

In LTE, resource scheduling algorithm is one of the key parameters that determine the overall system and UE performances in terms of throughput and fairness respectively. Multiple scheduling techniques are available that emphasizes on optimizing any one of the key system performance parameters. Among them the most potential algorithms are proportional fair (PF) and round robin (RR). PF optimizes UE throughput with a fairly high fairness index whereas RR provides the best fairness among the UEs but with a comparatively lower throughput. Moreover the scheduler performance is affected by the UE mobility and UE density. This can significantly degrade the overall system efficiency. In this paper we have analyzed and compared several LTE downlink performance parameters between PF and RR in heterogeneous network (HetNet) to determine which scheduling scheme is convenient for users with high mobility.

MTPA and Field Weakening Control of Synchronous Reluctance motor

An improved algorithm for MTPA (Maximum Torque Per Ampere) and Field Weakening operation which is suitable for implementation with Field Oriented Control, has been proposed for the Synchronous Reluctance motor (SynRel) for high dynamic performance. The proposed method overcomes the problem of excessive current flow into the machine while generating the d-axis and q-axis current commands independently. At the same time to operate the inverter in the linear modulation region (0≤m≤1) to minimize the output torque ripple. The proposed method helps to attain MTPA operation below the base speed to operate with the rated load and a fast speed response in Field Weakening mode. The validity and efficacy of the proposed algorithm is verified by simulation in MATLAB and SIMULINK.

Numerical optimization of absorber and buffer layers of CZTS thin film solar cells

In this paper, the performance of Cu<inf>2</inf>ZnSnS<inf>4</inf> (CZTS) thin film solar cell has been analysed numerically using SCAPS-1D. Firstly, the thickness, carrier density and defect density of CZTS absorber layer and then the thickness and carrier density of CdS buffer layer was varied to observe their effect on the cell performance. From the simulated results, the optimal thickness of 3000 nm, carrier density of 10¹⁶ cm⁻³ and defect density of 10¹⁵ cm⁻³ was obtained for CZTS. For CdS, optimal thickness of 60 nm and carrier density of 10¹⁷ cm⁻³ was obtained. Thus, the solar cell efficiency of 21.79% and fill factor of 68.79% (with VOC of 1.0017 V and JSC of 31.624 mAcm⁻²) has been achieved at 300 K. Finally, the effect of operating temperature on the cell performance showed that increased temperature would affect the efficiency in order of −0.25%/°C.

Smooth Track-Keeping and Real Time Obstacle Detection Algorithm and its PID Controller Implementation for an Automated Wheeled Line Following Robot

Line following automated robots is extensively used in industries for smooth running of production. This paper presents a simple and effective solution for path tracking problem for a wheeled automated mobile robot which can be used for material handling in industries. A PID controller has been used for controlling the robot which is capable of moving safely by smooth track-keeping in partially structured environment without any collision with static or moving objects. The purpose of the project is to build a mobile robot which will provide fast, smooth, accurate and safe movement in any given line or track. A straight or wavy line would be simple to follow whereas aT-junction, 90 degree bends, acute angle bends and grid junctions would be difficult to navigate through. This is due to the physical kinematics constraints which are limited to motor response, position and turning radius of the robot. A line sensor configuration has been proposed to improve the navigation reliability of the mobile robot which uses differential drive system. A dynamic algorithm has been developed for detecting and following a specified line which ensures the reliable and safe movement of the robot.