Showing papers by "Chittagong University of Engineering & Technology published in 2013"

Design and Implementation of Hybrid Automatic Solar-Tracking System

Abstract: A solar tracker is a system for orienting solar photovoltaic modules and solar thermal collectors toward the sun. This paper presents a microcontroller based energy efficient hybrid automatic solar-tracking system with a view to assess the improvement in solar conversion efficiency. The two-axis solar-tracking system is constructed with both hardware and software implementations. The proposed tracking system uses a new solar position sensor with adaptive features. A comparative analysis was performed using four systems, i.e., hybrid tracking, dual-axis, single-axis, and stationary module. The results showed that the use of the dual-axis tracking system produced 18% gain of power output, compared with a single-axis tracking system. The gain of output power with the hybrid tracking system was much higher (54%) when compared with a stationary system inclined at 23.5 deg to the horizontal. Considering the state of the art of the technology, successful strategy, robust control philosophy, and the potential added benefit of this research work can be employed on a large scale in sustainable manner.

Introducing speed breaker as a power generation unit for minor needs

Abstract: Man in his lifetime, uses energy in one form or the other. Energy demand continues to grow, year after year. In the present scenario power becomes major need for human life. But the extensive usage of energy has resulted in an energy crisis, and there is a need to develop methods of optimal utilization, which will not only ease the crisis but also preserve the environment from the negative impacts of global climate change. Energy conservation is the cheapest new source of energy. It is an attractive technology for optimal use of available sources. This research shows the possibility of tapping the wasted energy in the road speed breaker. The wasted energy can be converted to the electrical energy by roller mechanism through several energy conversion processes. In this research, the obtained electrical energy is in KW range which is sufficient to lighten the street lights and traffic signal. As the number of vehicle is increasing day by day, the designed system will be effective to solve the power crisis of Bangladesh to some extent.

Strength and durability characteristics of concrete made with fly-ash blended cement

Abstract: Sustainability issue in construction sector came forward over the last two decades due to concerns regarding using virgin materials as well as emission of greenhouse gases from production of raw materials. Cement is the prime constituents of concrete and contributes approximately 7% of global man made CO2 production. Interest in blended cements is growing because of its advantages as increased production economy, reduced CO2 emissions and fuel consumption. This paper discusses the effects of cement replacement with supplementary cementitious material fly-ash on the strength development, water permeability and rapid chloride penetration resistance of concrete over the curing age of 365 days. Three different grades of concrete M38, M33 and M28, each with seven different fly-ash replacement level, 10, 20, 30, 40, 50, 60 and 70% were used for the experimental program. Ordinary Portland cement concrete was also used as reference concrete. Coefficient of permeability as well as rapid chloride penetration resistance was determined at an age of 28, 56, 90, 180 and 365 days whereas strength at 3, 7, 28, 56, 90, 180 and 365 days. Test results show that permeability of concrete decreases with the increase of fly-ash level up to an optimum value and then start to increase, whereas strength of concrete increases with the increase of fly-ash up to an optimum level and then starts to decrease. Among all the concretes studied, the optimum amount of cement replacement is reported to be 30%. The study reveals that fly-ash concrete is less permeable and achieves higher strength due to pozzolanic activity of fly-ashes that creates more durable calcium silicate hydrate and fills capillaries and bleed water channels occupied by water soluble lime. As a result fly-ash concrete inhibits the penetration of aggressive species including chloride which can effectively reduce the corrosion of the embedded steel reinforcement.

Numerical Analysis of Novel Back Surface Field for High Efficiency Ultrathin CdTe Solar Cells

Abstract: This paper numerically explores the possibility of high efficiency, ultrathin, and stable CdTe cells with different back surface field (BSF) using well accepted simulator AMPS-1D (analysis of microelectronics and photonic structures). A modified structure of CdTe based PV cell SnO2/Zn2SnO4/CdS/CdTe/BSF/BC has been proposed over reference structure SnO2/Zn2SnO4/CdS/CdTe/Cu. Both higher bandgap materials like ZnTe and Cu2Te and low bandgap materials like As2Te3 and Sb2Te3 have been used as BSF to reduce minority carrier recombination loss at the back contact in ultra-thin CdTe cells. In this analysis the highest conversion efficiency of CdTe based PV cell without BSF has been found to be around 17% using CdTe absorber thickness of 5 μm. However, the proposed structures with different BSF have shown acceptable efficiencies with an ultra-thin CdTe absorber of only 0.6 μm. The proposed structure with As2Te3 BSF showed the highest conversion efficiency of 20.8% ( V,  mA/cm2, and ). Moreover, the proposed structures have shown improved stability in most extents, as it was found that the cells have relatively lower negative temperature coefficient. However, the cell with ZnTe BSF has shown better overall stability than other proposed cells with temperature coefficient (TC) of −0.3%/°C.

Design of digital thermometer based on PIC16F77A single chip microcontroller

Abstract: This paper elucidates simple design method of a low cost digital thermometer based on PIC16F77A microcontroller and temperature sensor LM35. LM35 is an analog sensor which converts the surrounding temperature to a proportional analog voltage. The sensor's output is connected to one of the ADC (Analog to Digital Converter) channel inputs of the microcontroller to originate the equivalent temperature value in digital format. Within a short duration 10 digital values of temperature are stored and computed to have maximum, minimum and average temperature among these. Then, the computed formats of temperature are displayed in a 16×2 character LCD in °C scale correspondingly. This design process is more convenient than others as it is more economical, efficient and simple.

A Novel Two Switch Non-inverting Buck-Boost Converter based Maximum Power Point Tracking System

Abstract: A solar module can’t transfer maximum power to the load itself due to impedance mismatch. A maximum power point tracking (MPPT) system could be employed to have the maximum power. A new MPPT system has been developed using Buck-Boost type DC-DC converter. The system is highly efficient and robust. PIC16F73 microcontroller has been used to control the DC-DC converter output. PV module output power is measured using microcontroller. The output power is compared with the previous module output power and the duty cycle of the converter is adjusted continuously to track MPP. This process repeats until the output power reaches near to the maximum power point.In this paper, a maximum power point tracking (MPPT) system is developed using two-switch non-inverting buck-boost converter. Perturb and observe (P & O) MPPT algorithm is used to transfer maximum power from the PV panel which is executed using a microcontroller. DOI: http://dx.doi.org/10.11591/ijece.v3i4.2772

Moment invariants based object recognition for different pose and appearances in real scenes

Abstract: Object recognition in real scenes is a central problem in computer vision. In this paper we propose a new approach for shape based recognition of objects in real scenes. This approach uses moment invariants for identification of shape features. Moment Invariants are functions of central moments. They are invariant against linear transformations such as rotation, translation and scaling. Therefore, their integration provides recognition of objects in real scenes with different pose and appearances. In this way, the proposed approach does not only provide invariant object recognition, but also capable of dealing with challenges like variation in pose and appearances. We have used linear support vector machine (SVM) for classification of object and non-object data. With qualitative and quantitative experimental evaluation on standard INRIA Pedestrian dataset, we have compared performance of the proposed method with other state of the art shape feature descriptors based object recognition methods and demonstrated better performance over them.

Hydrological behaviour of a drained agricultural peat catchment in the tropics. 1: Rainfall, runoff and water table relationships

Abstract: Hydrological data of a drained tropical peat catchment have been analysed through conventional quantitative hydrological approaches to characterize its hydrological behaviours and changes due to continuous drainage for a long period. The results show that the hydrology of the catchment is extremely dynamic and the catchment is flashy in nature. A decreasing trend in peak flow amount and an increasing trend in baseflow amount was observed in the catchment, indicating that continuous drainage has reduced the risk of both flooding and water scarcity in the catchment. Correlation analysis among rainfall, runoff and groundwater table reveals that saturation excess-near surface flow is the dominant mechanism responsible for rapid runoff generation in the catchment. Therefore, any physical alterations or disturbances to the upper part of the peat profile would definitely affect the overall hydrological behaviour of the peat catchment.Editor Z.W. Kundzewicz; Associate editor D. HughesCitation Katimon, A.,...

User-authentication approach for data security between smartphone and cloud

Abstract: Cloud computing architecture provides a proper management to share distributed resources and services throughout the world via computer network. This architecture offers three main features, e.g. SaaS, PaaS and IaaS. And today's Smartphones are more compatible with this architecture, especially with IaaS because of its small storage capacity. Smartphones have become almost computer and these can be viewed as a miniature of personal computer. Since cloud computing share distributed data via network in the open environment so, there may occur security problems. To address this problem, this paper has proposed a new data security approach for Smartphone in cloud computing architecture, which ensures secured communication system and hiding information from others. Security level is maintained using the Global Positioning System (GPS) and network provider which ensures strong user-authentication to secure our cloud.

An improved blind watermarking method in frequency domain for image authentication

Abstract: Digital watermarking has been widely used for copyright protection for multimedia data. This paper proposes a new watermarking method of image for copyright protection based on Hadamard transform. This method can embed or hide an entire image or pattern as a watermark such as a company's logo or trademark directly into original image for copyright protection. This watermarking method deals with the extraction of the watermark information in the absence of original image, hence the blind scheme is obtained. The experimental results prove that our proposed watermarking method offers better image quality and more robustness under various attacks such as JPEG compression, cropping, sharpening, filtering and so on. Peak Signal to Noise Ratio (PSNR) and Normalized Correlation Coefficient (NCC) are computed to measure image quality and robustness. Finally, a comparative study is made against the previous technique.

True three-phase bidirectional switch based AC-AC Buck-Boost converter topology

Abstract: A new three-phase true bidirectional switch is proposed in this paper. This switch consist of a unidirectional switch enclosed in two three phase diode bridges with bidirectional input and output terminals. A family of simple topologies of three-phase AC-AC converters using the true bidirectional switch is possible as direct extension of DC-DC converters having similar operating principle. Steady state analysis and simulation results are presented in this paper using the Buck-Boost topology as an example. Performance of the circuit has been found satisfactory with duty cycle variation. The proposed converter can be used for AC-AC line conditioning to overcome voltage sags, surges, and load fluctuations. Because the proposed converters employ only two active devices, they can reduce cost and complexity and improve system reliability.

Design and performance evaluation of PIC16F77A microcontroller based fluid velocity meter

Abstract: This paper elucidates simple design method of a low cost digital velocity meter based on PIC16F77A microcontroller This digital velocity meter identifies the linear velocity of any fluids as well as any kind of movable objects LASER and light dependent resistor are two cardinal sensors to design this meter By this sensor any moving object or moving fluid's initial and final time is calculated at a certain distance An electrical switch measure this time duration of certain distance very precisely With this input signal by using the velocity formula the single chip microcontroller compute the velocity Then the computed formats of velocity are displayed in a 16×2 character LCD It also shows the time duration of objects to pass the two sensors This design process is more effective than others as it is more economical, efficient and simple

Impact of Urban Development and Vegetation on Land Surface Temperature of Dhaka City

Abstract: This paper addresses both quantitative and qualitative assessment of the relationship between the land surface temperatures (LST) and land cover (LC) changes in Dhaka Metro Area (DMA) using Landsat TM/ETM+ data over the period from 1989 to 2010. The LC map was prepared using supervised classification methods. On the other hand, using the calibration of spectral radiance and emissivity correction LST has been derived from the thermal band of Landsat TM/ETM+. To establish the relationship between LST and LC, GIS based spatial simulation has been conducted. The changing of LST is found to be directly correlated with LC transition. LST has shown to increase in areas with growing urban developments. In contrary, the amount of Vegetation (NDVI) is negatively correlated with LST. The trend of LST and LC transitions indicates that LST will be abruptly increased in near future. The urban LST maps, the analyses of thermal-land cover relationships and the spatial simulated results thus obtained could be used as strategies for quality improvement of urban environment and a smart solution to the reduction of Urban Heat Island (UHI) effect.

Copper telluride as a nobel BSF material for high performance ultra thin CdTe PV cell

Abstract: Thin-film CdTe is one of the leading materials for high efficiency, low-cost and stable PV cells. The formation of a stable, low resistance, non-rectifying back contact to p-CdTe thin-film is the most critical challenge associated with this technology, another main constraint of PV technology is its high cost. To reduce the cost, less material consumption is desirable. Thus research is leading toward ultra-thin CdTe PV cell. However, the use of back surface field (BSF) material is found to be better, effective and easier one among several methods still used to overcome the problem with the back contact. This paper numerically explores the possibility of high efficiency, ultra-thin and stable CdTe cells with Cu2Te BSF. The cell performances (Voc, Jsc, FF, efficiency, temperature stability) are investigated by recognized simulator `Analysis of Micro-electronics and Photonic Structures' (AMPS-1D). A modified structure of CdTe based PV cell SnO2/Zn2SnO4/CdS/CdTe/Cu2Te/Ni has been proposed over reference structure SnO2/ Zn2SnO4/CdS/CdTe/Cu. The simulated results have shown that the use of Cu2Te as BSF layer enhances the cell performances and has no adverse effect on cell stability. In this analysis the highest conversion efficiency of CdTe based PV cell without BSF has been found around 17% using CdTe absorber thickness of 5μm, on the other hand with the BSF the conversion efficiency has been found to be as high as 19.5% using only 0.6 μm thick CdTe absorber, which opens a new window for ultra-thin CdTe PV cells. Furthermore it was also found that the cell normalized efficiency linearly decreased with the increasing operating temperature at the gradient of -0.35%/C, which indicates better stability of the proposed CdTe PV cell.

Stairway Detection Based on Extraction of Longest Increasing Subsequence of Horizontal Edges and Vanishing Point

Abstract: Detection of stair region from a stair image is very crucial for autonomous climbing navigation and alarm system for blinds and visually impaired. In this regard, a framework is proposed in this paper for detecting stairways from stair images. For detection of the stair region, a natural property of stair is utilized that is steps of a stair appear sorted by their length from top to bottom of the stair. Based on this idea, initially, horizontal edge detection is performed on the stair image for detecting stair edges. In second step, longest horizontal edges are extracted from the edge image through edge linking. In third step, longest increasing subsequence (LIS) algorithm is applied on the horizontal edge image for extracting stair edge. Finally, the vanishing point is calculated from these sets of horizontal lines to confirm the detection of stair candidate region. Various stair images are used with a variety of conditions to test the proposed framework and results are presented to prove its effectiveness.

Heart rate variability analysis using approximate entropy and detrended fluctuation for monitoring heart condition

Abstract: Variation in time between two successive heart beats occurring due to internal and external stimulation causes Heart Rate Variability (HRV). HRV is a tool for indirect investigation of both cardiac and autonomic system function in both healthy and diseased condition. It has been speculated that HRV analysis by nonlinear method might bring potentially useful prognosis information into light which will be helpful for assessment of cardiac condition. In this study, HRV from two types of data sets (normal sinus rhythm and sinus arrhythmia) are analyzed which are stored in MIT-BIH (Massachusetts Institute of Technology - Beth Israel hospital) database, an extended collection of recorded physiological signals. Then two nonlinear methods, approximate entropy (ApEn) and detrended fluctuation analysis (DFA), have been applied to analyze HRV of both Arrhythmia patients and people having normal sinus rhythm. It has been clearly shown that nonlinear parameters obtained from these two methods reflect the opposite heart condition of the two types of subjects under study, healthy and diseased, by HRV measures. Thus, value of the nonlinear parameters found in this work can be used as standard when treating suspected patients for diagnosis of Arrhythmia. Also, by measuring these nonlinear parameter values, heart condition can be understood.

Benefit functions for instream water uses: A case of the Teesta River, Bangladesh

Abstract: The functional relationship between benefit level and resource availability, which is demonstrated in a marginal benefit (MB) function but not in a total benefit (TB) function, is mostly absent in environmental valuation studies. This paper aims to establish the total and MB functions for instream water direct uses. Incomes of the beneficiaries considered as the water-use benefit and its seasonal variation within a year obtained from a semi-structured primary survey are used to establish a quadratic TB and subsequently a linear MB function. The Teesta River from Bangladesh is taken as a case study where capture fishery and small-scale navigation are the instream water direct uses on which many riparian poor rely for their livelihood. Despite several challenges including data paucity, the study carries importance to persuade instream flow provision and safeguard the livelihoods of the poor riparian communities in a developing country perspective.

High performance In x Ga 1−x N Tandem solar cells designed from numerical analysis

Abstract: Multijunction tandem solar cells from compound materials are highly attractive for higher cell efficiency need to be applied in space applications In this work, numerical simulations were conducted with novel promising InGaN compound material by utilizing AMPS simulator to explore the possibility of higher efficiency of the multi-junction tandem solar cell This simulation was done with the different ratio of In and Ga content to investigate the optimum band gap combinations of tandem solar cells, and it has been found that the maximum conversion efficiency of the triple junction tandem solar cell is 4234% (Voc =133V, Jsc=3615mA/cm2, and FF =088) with this InGaN compound material Finally, the stability of the designed cell has been investigated and found that the temperature coefficient (TC) of the proposed cell is -004%/°C which indicates the higher stability of the cell in stressed condition

An intelligent human-robot interaction framework to control the human attention

Abstract: Attention control can be defined as shifting someone's attention from his/her existing attentional focus to another. However, it is not an easy task for the robot to control a human's attention toward its intended direction, especially when the robot and the human are not facing each other, or the human is intensely attending his/her task. The robot should convey some communicative intention through appropriate actions according to the human's situation. In this paper, we propose a robotic framework to control the human attention in terms of three phases: attracting attention, making eye contact, and shifting attention. Results show that the robot can attract a person's attention by three actions: head turning, head shaking, and uttering reference terms corresponding to three viewing situations in which the human vision senses the robot (near peripheral filed of view, far peripheral field of view, and out of field of view). After gaining attention, the robot makes eye contact through showing gaze awareness by blinking its eyes, and directs the human attention by the combination of eye and head turning behavior to share an object. Experiments using sixteen participants confirm the effectiveness of the propose framework to control human attention.

Performance evaluation of reference current extraction methods for hybrid active power filter

Abstract: Active power filter (APFs) has been used to mitigate the harmonic pollution in an electrical network. Reference current estimation is an important part for control of an active power filter. In any inaccuracy in generation of reference current, it yields to poor compensation in load current harmonics. This paper deals with five types of time domain control techniques for real time compensating current for shunt hybrid active power filter. This work also reveals the advantages and disadvantages of the practiced control strategies. The five strategies are analyzed and compared in terms of their performance under balance source and balance load conditions. The comparison and effectiveness of all the methods are based on the theoretical analysis and simulation results obtained with MATLAB/SIMULINK power system block set employing in a three phase three wire network. Here, a three phase six pulse rectifier with R-Load is considered as a nonlinear load.

Seismic response analysis of base isolated building: effect of lead rubber bearing characteristics

Abstract: Seismic response of a base isolated building is studied for varying properties of Lead rubber bearing. An eight storied educational building is taken into consideration as a structure of interest. Properties of the lead rubber bearing are altered to find the most optimum value of important parameters to obtain a minimum earthquake response of the building. The most important parameters are taken into consideration: initial stiffness (K1), yield strength (Fy/W) and post-to-pre yield stiffness (K2/K1). Three different ground motions are considered in the present analysis and applied in the longitudinal direction of the structure. Base shear, roof acceleration and bearing displacement are utilized to evaluate the performance of the isolated building. It is found that these parameters influence the response of the building significantly and seismic response of the structure reaches to a minimum value for a specific value of the bearing parameter. Finally, some recommendations are made based on the present seismic analysis with different ground motions.

Evaluating Test Methods for Rapidly Assessing Fly Ash Reactivity for Use in Concrete

Abstract: In addition to various properties, including fineness and loss on ignition, used to assess fly ash, specifications covering the material as an addition in concrete normally include a measure of its pozzolanic activity. While variations exist, approaches commonly used involve testing the compressive strength of standard fly ash mortar, at different ages, and comparisons with the corresponding Portland cement control. Given the nature of the material, these can be carried out over extended periods (e.g. 90 days for Activity Index in BS EN 450-1). If the timescale was reduced, this could offer benefits with regard to fly ash testing and use. The paper will summarize various options in the literature towards achieving this and describe an investigation carried out to examine the potential of selected property measurements/techniques in the role. These include (i) fly ash characteristics: fineness, bulk chemistry and amorphous content; (ii) accelerated curing (elevated temperature) conditions for Activity Index and hydrated lime/fly ash mortars; and (iii) wet chemical tests involving lime-consumption. The methods were considered for a range of low-lime fly ashes covering different sources, seasonal variations and cocombustion, with evaluations made through comparisons against the Activity Index to BS EN 450-1. The paper will identify their relative effectiveness in assessing fly ash reactivity and explore how they relate to concrete. INTRODUCTION Fly ash has a long history of use in concrete, with early research investigating the material in this application dating back to the 1930s. Much of the work carried out on fly ash concrete has demonstrated that it offers a range of technical benefits, covering fresh and engineering properties, and aspects of durability. 3 Furthermore, it can provide environmental and economic advantages to construction. 4 Specifications for fly ash, corresponding to the period of the materials’ use, have been revised over time, to reflect experience gained and developments taking place in the power industry. One of the key characteristics, which can be traced to their early introduction, is a measure of fly ash reactivity (pozzolanic activity, see Table 1). 2013 World of Coal Ash (WOCA) Conference April 22-25, 2013 in Lexington, KY http://www.flyash.info/

OPTSDNA: Performance evaluation of an efficient distributed bioinformatics system for DNA sequence analysis.

Abstract: Storage of sequence data is a big concern as the amount of data generated is exponential in nature at several locations. Therefore, there is a need to develop techniques to store data using compression algorithm. Here we describe optimal storage algorithm (OPTSDNA) for storing large amount of DNA sequences of varying length. This paper provides performance analysis of optimal storage algorithm (OPTSDNA) of a distributed bioinformatics computing system for analysis of DNA sequences. OPTSDNA algorithm is used for storing various sizes of DNA sequences into database. DNA sequences of different lengths were stored by using this algorithm. These input DNA sequences are varied in size from very small to very large. Storage size is calculated by this algorithm. Response time is also calculated in this work. The efficiency and performance of the algorithm is high (in size calculation with percentage) when compared with other known with sequential approach.

Voltage Level and Transient Stability Enhancement of a Power System Using STATCOM

Abstract: The increased demands on transmission, absence of long term planning and need to provide open access to generating companies and customers have created tendency towards reduced quality of supply FACTS opens up new opportunities for controlling power and enhancing the usable capacity The Static Synchronous Compensator (STATCOM), based on voltage source inverter is a widely used FACTS device In this paper a 5-bus system is analyzed in term of voltage level and then optimum bus location is calculated to connect STATCOM to increase voltage level STATCOM is also connected to the mid-point of a line to investigate its effects on enhancing transient stability

Design and testing of a high frequency air-cored resonance transformer

Abstract: This paper has focussed on the step-by-step design of a high frequency air-cored resonance transformer commonly called Tesla coil. This work concentrates on the design and construction of a medium sized (1-3 kW) versatile Tesla coil that can be easily used for measurements and general research. The task is, therefore, to minimise the number of stochastic and unknown parameters influencing the device functionality and pointing out pros and cons of each solution. The physical dimension of the Tesla transformer has been chosen for the design purpose pursuing the accomplishment of an undergraduate project and also the availability of the regarding components in Bangladesh. This design has mainly two units' viz., a power supply and Tesla coil. The power supply which fed the Tesla coil having voltage rating 12 kV and current rating 120 mA has been designed by using three microwave oven components, i.e., microwave oven transformers (2.1 kV), capacitors (2,100 V, 1 μF), diodes (1N4003) each are two in numbers. These components are assembled as dual MOTs voltage doublers circuit. And necessary simulation has been performed by using MicroSim schematics.