Showing papers by "Chittagong University of Engineering & Technology published in 2014"
TL;DR: Progress in disulfide engineering is reviewed, with an emphasis on the issue of stability and computational methods that facilitate engineering efforts.
205 citations
TL;DR: In this paper, the authors explored the effects of the double counter twisted tapes on heat transfer and fluid friction characteristics in a heat exchanger tube and demonstrated that the Nusselt number, friction factor and thermal enhancement efficiency were increased with decreasing twist ratio.
113 citations
23 May 2014
TL;DR: A new embedding algorithm (NEA) of digital watermarking is proposed and evaluated by comparing performances with Cox's algorithm, the performances of NEA will compare among other algorithms like Gaussian sequence, image fusion, nonlinear quantization embedding with various attacking conditions in near future.
Abstract: The authenticity of content or matter is crucial factors for solving the problem of copying, modifying, and distributing the intellectual properties in an illegal way. Watermarking can resolve the stealing problem of intellectual properties. This paper considers a robust image watermarking technique based on discrete wavelet transform (WDT) and discrete cosine transform (DCT) called hybrid watermarking. The hybrid watermarking is performed by two level, three level, and four level DWT followed by respective DCT on the host image. A new embedding algorithm (NEA) of digital watermarking is proposed in this paper. The simulation results are compared with Cox's additive embedding algorithm and the NEA for additive white Gaussian noise (AWGN) attack and without attack. Both algorithms use the hybrid watermarking. The NEA gives 3.04dB and 9.33dB better pick signal to noise ratio (PSNR) compared to Cox's additive algorithm for the 4 level DWT for AWGN attack and without attack, respectively. Moreover, the NEA extracts the marked image 46 times better of Cox's additive algorithm in 2 level DWT with AWGN attack. That means, the NEA can embed larger marks and high quality marks extract from the embedded watermarking even attacking condition. Though the NEA is evaluated in this paper by comparing performances with Cox's algorithm, the performances of NEA will compare among other algorithms like Gaussian sequence, image fusion, nonlinear quantization embedding with various attacking conditions in near future.
47 citations
TL;DR: In this paper, the authors proposed a (G ′/G )-expansion method for finding exact traveling wave solutions of nonlinear partial differential equations (NLEEs) using hyperbolic, trigonometric and rational functions.
Abstract: The novel ( G ′/ G )-expansion method is one of the powerful methods that appeared in recent times for establishing exact traveling wave solutions of nonlinear partial differential equations. Exact traveling wave solutions in terms of hyperbolic, trigonometric and rational functions to the cubic nonlinear Klein–Gordon equation via this method are obtained in this article. The efficiency of this method for finding exact solutions and traveling wave solutions has been demonstrated. It is shown that the novel ( G ′/ G )-expansion method is a simple and valuable mathematical tool for solving nonlinear evolution equations (NLEEs) in applied mathematics, mathematical physics and engineering.
45 citations
TL;DR: In this article, the structural, elastic, electronic, optical and thermodynamics properties of sulvanite compounds were investigated using a different calculation code than that used by other workers and the results are compared.
Abstract: We present a systematic first-principles study of the structural, elastic, electronic, optical and thermodynamics properties of the sulvanite compounds Cu3TMS4 (TM = V, Nb and Ta). The structural, elastic and electronic properties are in fact revisited using a different calculation code than that used by other workers and the results are compared. The band gaps are found to be 1.041, 1.667 and 1.815 eV for Cu3VS4, Cu3NbS4 and Cu3TaS4, respectively which are comparable to other available calculated results. The optical properties such as dielectric function, refractive index, photoconductivity, absorption coefficients, reflectivity and loss function have been calculated for the first time. The calculated results are compared with the limited measured data on energy dependent refractive index and reflectivity coefficient available only for Cu3TaS4. All the materials are dielectric, transparent in the visible range. The values of plasma frequencies are found to be 15.36, 15.58 and 15.64 eV for Cu3VS4, Cu3NbS4 and Cu3TaS4, respectively. Furthermore, following the quasi-harmonic Debye model, the temperature effect on the bulk modulus, heat capacity, and Debye temperature is calculated reflecting the anharmonic phonon effects and these are compared with both experimental and other theoretical data where available.
39 citations
18 Dec 2014
TL;DR: In this article, the possibility of ultra-thin absorber layer of CdS/CdTe solar cell was investigated by numerical analysis utilizing AMPS (Analysis of Microelectronic and Photonic Structures) simulator.
Abstract: The polycrystalline cadmium telluride (CdTe) is regarded as one of the leading photovoltaic (PV) materials for its high efficiency and low-cost. The absorber material CdTe has the ideal and direct bandgap of 1.45 eV and it has a high absorption co-efficient over 5×10 5 /cm. In this work, the possibility of ultra-thin absorber layer of CdS/CdTe solar cell was investigated by numerical analysis utilizing AMPS (Analysis of Microelectronic and Photonic Structures) simulator. In the proposed cell, the CdTe layer was reduced and found that 1 �m CdTe layer is enough for acceptable range of cell conversion efficiency. The viability of this ultra-thin CdTe absorber layer was examined, together with 0.1 �m GeTe back surface field (BSF) layer to reduce the barrier height in the valence band and to minimize the recombination losses at the back contact of the CdS/CdTe cell. It was found that the proposed ultra-thin cells have conversion efficiency of 18.68% (Jsc = 21.47 mA/cm 2 , FF = 0.85, Voc = 1.02 V) without BSF and with 100 nm GeTe BSF conversion efficiency increased to 22.53% (Jsc = 24.28 mA/cm 2 , FF = 0.875, Voc = 1.06 V) with only 0.8 �m of CdTe layer. Moreover, it was found that the normalized efficiency of the proposed cells linearly decreased with the increasing operating temperature at the gradient of -0.16%/°C, which indicated better stability of the proposed CdTe solar cell.
26 citations
23 May 2014
TL;DR: In this paper, the authors investigated the possibility of ultra-thin absorber layer of CdS/CdTe solar cells and found that 1 μm CdTe layer is enough for acceptable range of cell conversion efficiency.
Abstract: The polycrystalline cadmium telluride (CdTe) is a leading photovoltaic (PV) material for the possibility of high-efficiency and low-cost thin film solar cell. The absorber material CdTe has a high absorption coefficient over 5×10
5
/cm and it has a direct bandgap of 1.45 eV, which is very close to the optimum bandgap for solar cells. In this work, numerical analysis was done utilizing AMPS (Analysis of Microelectronic and Photonic Structures) simulator to investigate the possibility of ultra-thin absorber layer of CdS/CdTe solar cell. In the proposed cell the CdTe layer was reduced and found that 1 μm CdTe layer is enough for acceptable range of cell conversion efficiency. The viability of this ultra-thin CdTe absorber layer was examined, together with 0.1 μm PbTe back surface field (BSF) layer to reduce the barrier height in valence band and to minimize the recombination losses at the back contact of the CdS/CdTe cell. It was found that the proposed ultra-thin cells have conversion efficiency of 21.11% (Voc = 1.04 V, Jsc = 23.509 mA/cm
2
, FF = 0.863) without BSF and with 100 nm PbTe BSF conversion efficiency increased to 21.83% (Voc = 1.05 V, Jsc = 23.895 mA/cm
2
, FF = 0.87) with only 0.8 μm of CdTe layer. Moreover, the normalized efficiency of the proposed cells linearly decreased with the increasing operating temperature at the gradient of -0.4%/°C, which indicated better stability of the cells with and without BSF.
25 citations
TL;DR: In this article, the authors used building-specific human vulnerability curves developed by the Central American Probabilistic Risk Assessment (CAPRA) to obtain possible loss of life estimates in the city of Sylhet, Bangladesh.
Abstract: To estimate human loss in an earthquake-prone area, it is necessary to analyze the role played by the spatiotemporal distribution of the area’s resident population. In order to evaluate earthquake impact, this article focuses on the spatiotemporal distribution of population and five scenario earthquakes that form the basis for loss estimation in the city of Sylhet, Bangladesh. Four temporal contexts (weekday, weekly holiday, the 30 days of Ramadan, and strike days) expand the more typical daytime and nighttime settings in which to examine hazard risk. The population distribution for every 2 hour interval in a day is developed for each type of day. A relationship between the occupancy classes and average space (persons per 100 m2) is used to distribute people in each building regardless of building locations. A total daytime and nighttime population is obtained for each building and the estimated nighttime population is used to model the population for four temporal scenarios in a year based on different factors and weights. The resulting data are employed to estimate population loss for each of the temporal and earthquake scenarios. This study used building-specific human vulnerability curves developed by the Central American Probabilistic Risk Assessment (CAPRA) to obtain possible loss of life estimates. The results reveal that there is a high positive correlation between the spatiotemporal distribution of population and the potential number of casualties.
24 citations
01 Oct 2014
TL;DR: Various window functions for designing FIR low pass filters and their comparative performance is given and in term of main lobe-width, the Kaiser window is the most supercilious among other windows.
Abstract: The finite impulse response (FIR) filter designed using window method is a very popular, simpler and well working for various applications. This paper presents various window functions for designing FIR low pass filters and their comparative performance is given. Performance of windows are analyzed in both time and frequency domains. In term of main lobe-width, the Kaiser window is the most supercilious among other windows. On the other hand, the Dolph-Chebyshev shows better response in stop-band attenuation. Hamming window achieves the response in between Kaiser and Dolph-Chebyshev windows. In terms of frequency selectivity Hanning plays better role than the others.
24 citations
18 Dec 2014
TL;DR: In this article, a solution of the power crisis of St.Martin Island with optimizing hybrid power generation scheme concentrating on sustainable energy is presented. But, it is not suitable for the use of diesel generators for four hours per day with large amount of CO2 emission.
Abstract: Modern era is looking at the sustainable energy for a permanent solution to the future power demand all over the world whereas the countries of the third world like Bangladesh is still failure to meet the present basic power demand. St.Martin Island is one of those places which are still out of national grid in Bangladesh. It is the most beautiful tourist island in the Bay of Bengal, which is in the most southern part and 17 km far away from the main land of Bangladesh. Grid connected electric system is quite impossible even in future because of costs and geographic location. Present electricity demand is partially fulfilled by stand-alone diesel generators only for four hours per day with large amount of CO2 emission. This paper is documented to give a solution of the power crisis of St.Martin Island with optimizing hybrid power generation scheme concentrating on sustainable energy. Using HOMER analysis, an optimum configuration is established among a set of systems to supply electricity to about 1400 families, 150 shops, 100 hotels and various organizations. The load calculation for the whole island has an outcome of a demand of energy about 4000kWh per day with a peak load of 504kW. This system incorporates a combination of 600kW decentralized Solar PV, 3 wind turbines of 1.8kW each, 2000 batteries of 800Ah each, 300kW biogas generator and 15kW diesel generator to fulfill the whole power demand of St.Martin Island. This configuration gives lowest cost of energy (COE) as BDT 15.04/ kWh (US$ 0.2/kWh) with a renewable fraction of 99.3%. It reduces CO2 emission significantly. This hybrid system may be an effective solution to the present electricity demand of St.Martin Island without hampering the environment. Besides, it may be an ideal example of a renewable hub because of its high renewable fraction. Keywords— Hybrid system, Off-grid, Solar, Wind, Biomass, high Renewable fraction, Less CO2 emission.
21 citations
23 May 2014
TL;DR: A location based emergency medical assistance system using OpenStreetMap (OSM) where the healthcare centers are mapped taking the waypoints of them and user of the application gets the text of nearest healthcare centers from user's current position during any emergency situations.
Abstract: Mobile Health can play a crucial role in emergency medical healthcare service. Because of rising road accidents in Bangladesh, anyone might need the information of nearest healthcare centers (e.g. hospitals, clinics, and diagnostic centers) right after the incidents occur. This instantaneous information can save the lives of victims of these accidents. Hence, we have proposed a location based emergency medical assistance system using OpenStreetMap (OSM) where the healthcare centers are mapped taking the waypoints of them. Our proposed system comprises a database as central server of the detail information about healthcare centers, android device with application installed on it and its user. User of the application gets the text of nearest healthcare centers from user's current position during any emergency situations. The application shows the markers of healthcare centers on the map along with audio information for visually impaired people. The distance between current location of the user and location of nearest healthcare center is calculated by haversine formula. The effectiveness of the system is tested at different locations in a mapped area.
29 May 2014
TL;DR: The recent developments in wind energy conversion systems with different wind turbine generators with their technical features and converter topologies, their classifications, choice of generators and their social and environmental benefits are presented.
Abstract: Energy is the most fundamental sector for the progression of a nation. The production of energy is going on from many years for the need of energy in all around the world but the true scenario is that the whole world is currently facing dreadful energy crisis in spite of numerous energy sources. So the production, distribution and the use of the energy should be as technological efficient as possible and incentives to save energy at the end-user should be set up. Two major technologies will play important roles to solve the future problems. One is to change the electrical power production sources from the conventional, fossil (and short term) based energy sources to renewable energy resources. The other is to use high efficient power electronics in power systems, power production and end-user application. This paper discusses trends of the most emerging renewable energy source, wind energy. With rapid development of wind power technologies and significant growth of worldwide installed capacity of wind power, wind energy conversion system has become a focal point in the research of renewable energy sources. This paper presents the recent developments in wind energy conversion systems with different wind turbine generators with their technical features and converter topologies, their classifications, choice of generators and their social and environmental benefits.
23 May 2014
TL;DR: Result of matching features in a neural network demonstrates that MFCC features work significantly to recognize speech.
Abstract: Analysis and detection of human voice at workplace such as telecommunications, military scenarios, medical scenarios, and law enforcement is important in assessing the ability of the worker and assigning tasks accordingly. This paper represents the results from a preliminary study to recognize the speech from human voice using mel-frequency cepstrum coefficients (MFCC) features. The 16 mel-scale warped cepstral coefficients were used independently for reorganization of speech from two Bangla commands of our native language. Cepstral coefficients for the utterance of `BATI JALAO' (i.e., TURN ON LIGHT) and `PAKHA BONDHO KORO' (i.e., TURN OFF FAN) from a particular speaker under preliminary investigation were used as features in a neural network. Network is trained using the MFCC features of two speakers in such a way that it can recognize only one particular person along with his command and terminate the program for other. Result of matching features in a neural network demonstrates that MFCC features work significantly to recognize speech.
TL;DR: In this paper, an attempt is made to extend the total strain energy approach for predicting the fatigue life subjected to mean stress under uniaxial state The effects of means stress on the fatigue failure of a ferritic stainless steel and high pressure tube steel are studied under strain-controlled low cycle fatigue condition.
Abstract: In this paper, an attempt is made to extend the total strain energy approach for predicting the fatigue life subjected to mean stress under uniaxial state The effects of means stress on the fatigue failure of a ferritic stainless steel and high pressure tube steel are studied under strain-controlled low cycle fatigue condition Based on the fatigue results from different strain ratios, modified total strain energy density approach is proposed to account for the mean stress effects The proposed damage parameter provides convenient means of evaluating fatigue life with mean stress effects considering the fact that the definitions used for measuring strain energies are the same as in the fully-reversed cycling (R = −1) A good agreement is observed between experimental life and predicted life using proposed approach Two other mean stress models (Smith-Watson-Topper model and Morrow model) are also used to evaluate the low cycle fatigue data Based on a simple statistical estimator, the proposed approach is compared with these models and is found realistic
18 Dec 2014
TL;DR: In this article, the authors presented modeling, analysis and simulation of a Dynamic Voltage Restorer (DVR) test systems using MATLAB Simulink for minimizing voltage sag by two promising controlling strategies: control using PI controller and control based on Park's Transformation.
Abstract: Modern electronics based on power electronic devices such as Programmable Logic Controllers (PLC), Distributed Control System (DCS) are used frequently in industrials plants to improve efficient production. These systems are extremely sensitive to power quality problem like voltage sag. Voltage sag is considered to be one of the most severe problems that cause failure, overheating and finally a total shutdown of industrial plants. It has been observed that, Dynamic Voltage Restorer (DVR) is the most efficient and effective modern custom power device exercised in power distribution networks to minimize voltage sags. The efficiency of the DVR depends on the performance of the control technique, which involved in switching the inverters. This paper presents modeling, analysis and simulation of a Dynamic Voltage Restorer (DVR) test systems using MATLAB Simulink for minimizing voltage sag by two promising controlling strategies: control using PI controller and control based on Park's Transformation. Simulation results of DVR controlling found by MATLAB Simulink here which demonstrates the well-organized plant applications. Moreover, this work shows that, control based on Park's Transformation provides better sag improvement than PI Control.
18 Dec 2014
TL;DR: In this article, the authors proposed a photovoltaic charging station architecture by using a combination of charge controller based on battery charging strategy with the unidirectional PWM technique based on the grid to vehicle strategy in Smart Grid.
Abstract: Utilization of Renewable energy resources is the most important field in a developing country like Bangladesh. Development of an effective method for evaluation of alternative energy sources in the automotive industry has always been a necessity for cost efficient design analysis. One viable energy source is electricity. Electric Vehicle (EV) is the application of this energy. In Bangladesh, Electric vehicle powered by rechargeable batteries are popular day by day. But due to redundancies use of electric energy it is needed to think of alternative sources of energy for running this vehicle. This paper proposed the photovoltaic charging station architecture by using a combination of charge controller based on the battery charging strategy with the unidirectional PWM technique based on the grid to vehicle strategy in Smart Grid. This paper makes a brief introduction and calculation on the power quality research object and takes data like power consumption by running EV. This paper also takes a comparative cost analysis of proposed smart charge station. Consequently, this paper could significantly increase the smart grid system and storage intermittent renewable energy from solar.
01 Dec 2014
TL;DR: A location based ATM locator system (LBALS) using OpenStreetMap, a growing open source digital map where ATM booths and fast tracks are mapped and Dijkstra's algorithm has been applied to show the possible shortest path between user and an ATM booth.
Abstract: Money transaction through ATM machine wherever we go has become phenomenon in our day-to-days activities as it is safe to keep a ATM card rather than keeping cash. When we need cash in any unknown area or during any emergency situation, we need to know about nearest ATM booth from where we can avail this opportunity. In addition, a tourist or new comer may face difficulty in having ATM help without this information. Hence, we have proposed a location based ATM locator system (LBALS) using OpenStreetMap, a growing open source digital map where ATM booths and fast tracks are mapped. Database contains detail information about all available ATM booths and fast tracks of different banks. It requires GPS supported android device with application installed on it for the user. Textual information are provided of nearest ATM booths or fast tracks from user's current position when he requires the information. Some Markers indicate ATM booths or fast tracks on the map. Dijkstra's algorithm has been applied to show the possible shortest path between user and an ATM booth. Haversine formula is also used to calculate perpendicular distance. Implemented LBALS is tested for some random locations in a specific region of our country.
10 Apr 2014
TL;DR: A `fault current' (due to asymmetric faults) analysis and comparisons between HVAC and HVDC transmission system are presented and a comparison of the simulation output-lower fault current, less fault effect, better performance & higher reliability is demonstrated for HVDD transmission system.
Abstract: `Fault current' is the flow of abnormal current through an improper path due to electric faults which causes enormous damages. In HVAC transmission system, Fault current due to electric faults is too large which affects the overall power system including-Receiving & Sending end bus, Transmission system, Load and even also the Power Generation Unit. HVDC transmission system dramatically reduces these effects, as the fault current due to electric faults is much lower, and only affects the individual faulty section of the overall transmission system. In favor of HVDC system, this paper presents a `fault current' (due to asymmetric faults) analysis and comparisons between HVAC and HVDC transmission system. MATLAB (Simulink) simulation software is used to simulate both HVAC & HVDC power transmission system topologies. From the comparison of the simulation output-lower fault current, less fault effect, better performance & higher reliability is demonstrated for HVDC transmission system.
TL;DR: This paper proposes aspatial skyline query for groups of users located at different positions that selects a set of spatial objects to fulfil the groups’ needs and performs several extensive experiments to show the effectiveness of this approach.
Abstract: A skyline query finds objects that are not dominatedby another object from a given set of objects. Skylinequeries can filter unnecessary information efficiently andprovide us important clues for various decision makingtasks. Now a days, GPS devices and location based servicesare very popular and they can easily connect users andmake groups. Conventional skyline queries are not sufficientto obtain valuable knowledge to fulfil the needs of suchgroups. Considering this fact, in this paper, we proposed aspatial skyline query for groups of users located at differentpositions. Our proposed skyline query algorithm selects a setof spatial objects to fulfil the groups’ needs. For example, ifa group wants to find a restaurant to hold a meeting, ourmethod can select a convenient place for all users of thegroup. We performed several extensive experiments to showthe effectiveness of our approach.
01 Dec 2014
TL;DR: Simulation results indicate that the proposed watermarking method is highly robust against different attacks, has high data payload and provides good imperceptible watermarked sounds, and shows superior performance than the state-of-theart water marking methods reported recently.
Abstract: This paper presents a blind audio watermarking method based on lifting wavelet transform (LWT) and QR decomposition (QRD) for audio copyright protection. In our proposed method, initially the original audio is segmented into non-overlapping frames. Watermark information is embedded into the largest element of the upper triangular matrix obtained from the low frequency LWT coefficients of each frame. A blind watermark detection technique is introduced to identify the embedded watermark under various attacks. Simulation results indicate that the proposed watermarking method is highly robust against different attacks. In addition, it has high data payload and provides good imperceptible watermarked sounds. Moreover, it shows superior performance than the state-of-theart watermarking methods reported recently.
23 May 2014
TL;DR: This paper proposed an innovative idea to detect induction motor stator's inter-turn short circuit fault using noninvasive heuristic approach by Artificial Neural Network (ANN).
Abstract: Induction motors are used extensively for various industrial applications. These motors have to endure and cope with a wide variety of environments and conditions, so with time gradually developing (incipient) faults build up. If the fault is not trace out in embryonic state, it leads degradation which eventually causes potential failure of the motors and huge economic loss in industry. Around two fifth incipient faults happen due to stator faults caused by mainly failure of inter-turn insulation. So this paper proposed an innovative idea to detect induction motor stator’s inter-turn short circuit fault using noninvasive heuristic approach by Artificial Neural Network (ANN). In this fault detection research, a 0.5 hp, single phase 50Hz induction motor at no load condition is used as an experimental prototype. Generalized Feed forward neural network is used as NN with Levenberg Marquardt gradient descend algorithm for training. Three input parameters (motor current, supply voltage and rotor speed) develop the feature space of NN to detect whether the motor is faulty or not by analyzing performance function. By the experiment, the proposed system is found more efficient, reliable, economical and smart than the existing system.
10 Apr 2014
TL;DR: In this paper, a low cost PIC microcontroller and C#.NET based vibration analysis system for general purpose uses like laboratory equipment or study material from commercially available equipment is presented.
Abstract: Vibration measurement and its real-time graphical representation is often required for analysis of physical conditions of machines, engines as well as in scientific researches, earth-quake amplitude measurement etc. This project work was intended to develop a system for measurement and real-time visualization of vibration. An electronic accelerometer sensor facilitates the vibration sensing procedure. The measured value is then transmitted to the visualization software installed in a personal computer which provides quantitative and qualitative information about the vibration phenomena in addition with a real-time graphical visualization feature. Two test cases were selected to verify the performance of the system. The first one was implemented to visualize and measure vibration parameters of a simple plastic stand, and the second one was intended to test the system performance on an induction motor for measurement and visualization of its horizontal vibration parameters. The performance analysis in the above mentioned cases confirms the stability and reliability of the system in vibration analysis for frequency range up to 5 kHz. This concludes to a low cost vibration analysis system for uses in medium range vibration analysis like earth quake monitoring, machine vibration level monitoring etc. Though there are many available vibrations analysis systems are available, this paper work is intended to derive the process of building a low cost PIC microcontroller and C# .NET based vibration analysis system for general purpose uses like laboratory equipment or study material from commercially available equipment.
TL;DR: In this article, high purity nanocrystalline α-alumina powder was mixed with 20 wt% ZrO2 by slurry method sintered at temperature (Ts) 1450°C, 1500°C and 1600°C for 2 hours.
Abstract: High purity nanocrystalline α-alumina powder was mixed with 20 wt% ZrO2 by slurry method sintered at temperature (Ts) 1450°C, 1500°C, 1550°C and 1600°C for 2 hour. The density, porosity, structural properties and mechanical properties of Al2O3-ZrO2 composites with respect to sintering temperature have been explored in the present work. The XRD spectra indicate that α-Al2O3, t and m-ZrO2 are the crystalline phases present in 20 wt% ZTA composites for all sintering temperature. It is observed that with higher sintering temperature the intensity of m-ZrO2 phases increases and the t-ZrO2 phases decreases. However, t-ZrO2 retention becomes much easier to trigger the transformation to monoclinic. Higher density of 20 wt% ZTA has been achieved at 1600oC, whereas the highest porosity was obtained for sintering temperature 1450°C.The microstructures of the samples was studied by using SEM which represents highly homogeneous and finer structure at 1600oC. The effect of sintering temperature on hardness, elastic modulus and flexural strength were investigated and has been found to increase with the increase of sintering temperature. Maximum
TL;DR: The study revealed the living conditions of the female laborers of tea garden in Bangladesh exploring the social and job environment with the inclusion of consciousness level as the deplorable scenario of their life styles as mentioned in this paper.
Abstract: The study reveals the living conditions of the female laborers of tea garden in Bangladesh exploring the social and job environment with the inclusion of consciousness level as the deplorable scenario of their life styles. This research has been done in a tea garden of Sylhet district in Bangladesh namely Lackatoorah Tea Estate, as the study area, taken into account at random. It shows that female workers are being oppressed and suppressed in each and every sphere of life as from family residence to job field. It also exhibits very explicitly that 68 percent of female workers have no control over their own income. 94 percent have no hereditary property ownership though they are entitled to get it legally from their family. 92 percent females think that they are being physically tortured and mentally harassed by their husband, male members of family and also by representative of estates manager. 86 percent women want to keep small size of family but cannot play role in the decision making of child issue. The study is fully based on primary level data that followed stratified sampling method with triangulation research design and reviewing some related literatures from past research reports.
18 Dec 2014
TL;DR: This paper presents a computer controlled electronic device called `Helping Hand' that can be used for the rehabilitation process of monoplegia patients by assisting him/her in physical therapy sessions and collects data of upper limb movements of patients for analysis and generates a report based on analysis.
Abstract: Monoplegia is a paralysis of a single limb; usually an arm and patients having monoplegia usually cannot regain their full-potential. Physical therapy is most beneficial for the treatment of monoplegia. However, this physical therapy includes monotonous exercises which seems dull to the patient. Computer assisted technology may be used to assist the patient for doing the physical exercises more effectively and enjoyably. In this paper, we present a computer controlled electronic device called ‘Helping Hand’ that can be used for the rehabilitation process of monoplegia patients by assisting him/her in physical therapy sessions. The system collects data of upper limb movements of patients for analysis and generates a report based on analysis. Finally, this report will be sent to the doctor for observing the improvement of rehabilitation phase of the patient. This system can reduce the workload of physical therapists and improve the effect of rehabilitation exercise for upper limb monoplegia patients.
10 Apr 2014
TL;DR: A design of detection system which can detect fatigue in drivers based on computer vision is proposed and aims to be more cost effective than industrial installments and therefore all parameters have been analyzed under laboratory environment and frames have been captured with a low cost webcam.
Abstract: Fatigue or drowsiness is one of the main reasons of inattention of drivers. Now a day Computer Vision is a very active field to detect specific human physiology and behavior during driving to detect driver's drowsiness. This paper proposes a design of detection system which can detect fatigue in drivers based on computer vision. The system approaches to detect fatigued drivers by first, detecting the face from a video sequence of driver's frontal face followed by locating the eye from the extracted face. Secondly, system finds the existence of eye pupil from detected eye and measures the blink rate simultaneously and by analyzing these parameters, system measures the loss of awareness before driver completely loss his/her attention. The proposed system aims to be more cost effective than industrial installments and therefore all parameters have been analyzed under laboratory environment and frames have been captured with a low cost webcam.
08 Dec 2014
TL;DR: Output/input voltage feedback and boost inductor average current tracking method is used for controlling the regulator and the average inductor current tracking control shows acceptable regulation of the converter output voltage.
Abstract: A two bi-directional switch based three-phase boost AC voltage regulator is presented in this paper. The operational principle of the proposed three-phase regulator is a direct consequence of using two three-phase bi-directional switches in the boost converter topology. The topology has reduced number of switches for a three-phase AC voltage regulator having output voltage regulation, input current shaping and power factor improvement capability. It provides opportunity for simple control technique to be adopted. In this paper output/input voltage feedback and boost inductor average current tracking method is used for controlling the regulator. Reduced number of switches allows simple control circuit, less switching loss, reliable operation and low cost. Steady state analysis and simulation results of close loop control of the proposed converter are presented in this paper. The average inductor current tracking control shows acceptable regulation of the converter output voltage. During sudden variation of load or input voltage the controller adjusts the duty cycle to recover to the desired output voltage. Experimental investigation of the converter without any feedback control is also described.
18 Dec 2014
TL;DR: In this article, a microstrip array antenna to achieve dual circular polarization is proposed, which can excite both right-hand circular polarization (RHCP) and left-hand linear polarization (LHCP) without using any 90° hybrid circuit or PIN diode.
Abstract: Design of a microstrip array antenna to achieve dual circular polarization is proposed in this paper. The proposed antenna is a 2×2 array antenna where each patch element is circularly polarized. The feed network has microstrip lines, cross slot lines and air-bridges. The array antenna can excite both right-hand circular polarization (RHCP) and left-hand circular polarization (LHCP) without using any 90° hybrid circuit or PIN diode. “Both-sided MIC Technology” is used to design the feed network as it provides flexibility to place several types of transmission lines on both sides of the dielectric substrate. The design frequency of the proposed array antenna is 10 GHz. The simulated return loss exhibits an impedance bandwidth of greater than 5% and the 3-dB axial ratio bandwidths for both RHCP and LHCP are approximately 1.39%. The structure and the basic operation along with the simulation results of the proposed dual circularly polarized array antenna are demonstrated in this paper.
23 May 2014
TL;DR: In this article, the design of a circularly polarized array antenna at 10 GHz frequency is presented, which consists of a 1×2 array antenna with feed circuit, dual-orthogonal feed circuit is used that excites two orthogonal modes with equal amplitude but quadrature in phase.
Abstract: In this paper, the design of a circularly polarized array antenna at 10 GHz frequency is presented. The proposed antenna consists of a 1×2 array antenna with feed circuit. To realize circular polarization, dual-orthogonal feed circuit is used that excites two orthogonal modes with equal amplitude but quadrature in phase. Feed circuit is designed using microstrip lines and slot lines where microstrip lines are placed on the top surface of the substrate and slot lines on the reverse side of the substrate. The feed point is chosen in such a way that it provides the each patch element two RF signals with 90° phase difference. Therefore, the circular polarization is realized by employing microstrip-slot feed circuit. “Both-Sided MIC Technology” is used to design the proposed array antenna as it gives flexibility in the design process. The simulated return loss of the proposed array antenna is less than -45 dB at the design frequency. The 3 dB axial ratio bandwidth of 0.8% is obtained. The structure and the basic behavior along with the simulation results of the proposed circularly polarized array antenna are demonstrated in this paper.
01 Oct 2014
TL;DR: In this article, a Stirling engine with displacer swept volume of 7.37 × 10-4 m3 can generate 80 watt of electrical power at 115 rpm engine frequency.
Abstract: Different processes that use energy and machines that do work do not have perfect efficiency. So energy is wasted from these processes in the form of heat. Power generating stations, industrial processes, rice mills, brick fields and other human activities are major sources of waste heat. Mud stoves used in rural areas for cooking purpose produce above 85% of waste heat. This wasted heat can be used to generate electrical power using Stirling engine (SE). Stirling engine is a heat engine that is operated at different temperature levels by cyclic operation of compression and expansion of working gas. A DC generator is coupled with the SE to generate electrical energy. In this research amount of waste heat from significant sources has been presented and theoretical analysis has been made to harvest electrical power using a displacer type SE. Utilizing helium as working fluid and a DC generator having 90% efficiency a SE with displacer swept volume of 7.37 ×10-4 m3 can generate 80 watt of electrical power at 115 rpm engine frequency. In this mathematical approach the phase angle is 90o and the temperature difference is about 150 0K. The setup discussed is working as a personal power plant for each rural household.