OALib Journal期刊

ISSN: 2333-9721




2017 ( 3 )

2016 ( 9 )

2015 ( 71 )

2014 ( 127 )


匹配条件: “Dey Avijit” ,找到相关结果约1156条。
MATLAB Solution of microstrip chebyshev Low pass filter system parameters by insertion loss method
Amiya Dey,Avijit Paul,Tanajit Manna
International Journal of Electronics and Computer Science Engineering , 2012,
Abstract: We propose the practical solution for overcoming the tedious job of detail calculation and corresponding rigorous analysis of several system parameter values associated with the design, testing and troubleshooting of Microwave Microstrip Chebyshev Lowpass Filter (LPF) by Insertion Loss Method. The entire above spoken Microwave Lowpass filter system modeling and performance analysis are implemented using MATLAB.
Adaptive System Simulation and Noise Analysis Toolbox (ASSNAT) : The Open-Source Toolbox Developed with Newer Features for Adaptive System Simulation
Ajoy Kumar Dey,Susmita Saha,Avijit Saha,Shibani Ghosh
Universal Journal of Computer Science and Engineering Technology , 2010,
Abstract: This paper introduces Adaptive System Simulation and Noise Analysis Toolbox (ASSNAT) version 1.1 (v1.1), which is an open- source MATLAB based software package for simulation and analysis of Adaptive signal processing systems and noises, with its new feature Learning curve method, where we can make an advanced level comparative study based analysis. ASSNAT v1.1 contains a variety of adaptive systems, filter algorithm and a wide range of input signals for simulation in a user friendly graphical interface. Central and advanced features, underlying models and algorithms, and case studies are presented in this paper to demonstrate the capabilities of this toolbox and its suitability for educational and research purposes.
ISO 50001: Are the Auditors Equipped Enough?  [PDF]
Avijit Choudhury
Open Journal of Energy Efficiency (OJEE) , 2012, DOI: 10.4236/ojee.2012.13006
Abstract: This paper tries to address the issue of expertise and awareness level of ISO-50001 [1] certification auditors in judging the efficacy of existing energy management (EnMS) and suggest the methodology to ensure continual improvement in EnMS. This article also tells about the need of thorough understanding of legal & other mandatory requirements which need to be addressed properly before framing the energy policy and setting up objectives & targets for the organization. Particularly SMEs, while implementing any standard or adopting any new system, largely depend on the consultant/ system auditor because of their limited knowledge and resources. In such cases the auditors need to play a larger role by making appropriate ENCON recommendations and guide them how to achieve the compliance. Further in India, most of the companies have got poor metering system. Even crucial energy data like flow rate of LPG, natural gas, FO, steam etc are quoted from judgment or past experience. Meters are not there to measure motor power, liquid temp or gas prss. In such cases auditors need to guide the clients how to establish the energy monitoring & targeting system and how to establish proper M&V (Measurement & Verification) protocol. In nut shell the ISO-50001 auditor needs to play the role of a friend, philosopher & guide to ensure that at the end of the day his client has complied with all the energy regulations and at the same time achieved some significant reduction in energy consumption.
HVAC vs Geothermal Heat Pump—Myth & Truth  [PDF]
Avijit Choudhury
Open Journal of Energy Efficiency (OJEE) , 2013, DOI: 10.4236/ojee.2013.21007
Abstract: In India energy auditors in some cases have recommended ground water based heat pump in place of common HVAC system to achieve better efficiency. However the users were made to understand that heat pumps are not suitable for Indian climatic condition and it produces no better result than the conventional system. This article tries to find answer to this debate thru an impartial analysis with the available data. First the concept is tested thermodynamically to compare the derived COPs and next from the experimental data on specific energy consumption.
Energy Audit Methodology of Sponge Iron Manufacturing Units Using DRI Process  [PDF]
Avijit Choudhury
Open Journal of Energy Efficiency (OJEE) , 2014, DOI: 10.4236/ojee.2014.33005
Abstract: Conducting complete energy audit (both process and utility) of a sponge iron unit is challenging as there is no laid down procedure to audit the process side. Further, the average heat to power ratio (kWth/kWe) of sponge iron plants ranges from (25:1) to (31:1). This shows that the manufacturing process mostly uses thermal energy and application of electrical energy is insignificant. The main & only source of thermal energy is coal and the entire coal is fed to the rotary kiln. Therefore we find that “Kiln” is the “Black-Box” of this industry and the success of energy efficiency is hidden in the kiln process chemistry. This article tries to establish detailed energy audit methodology of sponge iron manufacturing process or kiln operation with a view to finding out major energy saving potential of the unit. In the research work we find that it is the incomplete reaction of coal that causes the major energy inefficiency in the process. Substantial amount of un-reacted carbon comes out with the char (by-product) which has virtually zero commercial value. The article also puts a question mark on the justification of using high-grade imported coal in such energy inefficient industries.
Dey Avijit,Abdur Rahman S.M.,Ahsanul Akbar Mohammad,Hamiduzzaman Md.
International Research Journal of Pharmacy , 2012,
Abstract: The aim of this study was to evaluate the analgesic and anti-diarrheal activity of the whole plant Boerhavia repens. Sun dried roots, stems, barks and the leaves of B. repens were extracted using methanol at room temperature. The crude methanol extract was fractionated in two different solvents using Petroleum ether and Carbon Tetrachloride. The peripheral analgesic activity was evaluated by acetic acid induced Writhing method. The petroleum ether soluble materials at a dose of 400 mg/kg exhibited significant analgesic activity with 37.05% inhibition of writhing compared to that of 50% produced by the standard diclofenac. Evaluation of central analgesic activity was carried out by tail flicking method using Morphine as a positive control. Petroleum ether soluble fraction exhibited highest central analgesic activity after 30 minutes at a dose of 400 mg/kg dose. The central analgesic activity decreased in a time dependent manner. After 90 minutes there was almost no central analgesic activity. The anti-diarrheal activity of the different fractions of the crude extract of B. repens was evaluated using the model of castor oil induced diarrhea in mice. No fractions showed significant anti-diarrheal activity.
Dey Avijit,Raihan Sarkar Md.,Sariful Islam Howlader Md.,Hamiduzzaman Md.
International Research Journal of Pharmacy , 2012,
Abstract: Acanthus ilicifolius is an important medicinal plant having widespread application in a variety of disorders. The aim of this study was the phytochemical investigation and evaluation of the anti-oxidant, anti-microbial and cyto-toxic activities of Acanthus ilicifolius. The stem of A. ilicifolius was separated from the other plant parts and sun dried and extracted using methanol at room temperature. Phytochemical screening of the stem of A. ilicifolius ensured the presence of steroids, alkaloid, flavonoids, glycosides, tannins and reducing sugar in the crude methanol extract. The anti-oxidant activity was measured by DPPH free radical scavenging activity. In the quantitative assay, the extracts of A. ilicifolius stem displayed significant free radical scavenging activity (IC50 = 5.1 μg/ml) which is comparable to that of ascorbic acid (IC50 = 4.6 μg/ml), a well-known standard antioxidant. The anti-microbial activity of different fractions was measured by disc diffusion method using Kanamycin as a standard. The crude methanol extract did not reveal any significant anti-microbial activity. Evaluation of cyto-toxic activity was done using the brine-shrimp lethality bio-assay. The crude extract was found to show strong lethality against the brine shrimp nauplii. These results tend to suggest its possible antitumer, antibacterial or pesticidal activities.
A Study of Porosity Effect on Tribological Behavior of Cast Al A380M and Sintered Al 6061 Alloys  [PDF]
Avijit Sinha, Zoheir Farhat
Journal of Surface Engineered Materials and Advanced Technology (JSEMAT) , 2015, DOI: 10.4236/jsemat.2015.51001
Abstract: Due to their light weight, high corrosion resistance and good heat conductivity, aluminium alloys are used in many industries today. They are suitable for manufacturing many automotive components such as clutch housings. These alloys can be fabricated by powder metallurgy and casting methods, in which porosity is a common feature. The presence of pores is responsible for reducing their strength, ductility and wear resistance. The present study aims to establish an understanding of the tribological behavior of high pressure die cast Al A380M and powder metallurgy synthesized Al 6061. In this study, dry sliding wear behavior of Al A380M and Al 6061 alloys was investigated under low loads (1.5 N – 5 N) against AISI 52100 bearing steel ball using a reciprocating ball-on-flat configuration and frequency of 10 Hz. Wear mechanisms were studied through microscopic examination of the wear tracks. This study revealed that due to combined effect of real area of contact and subsurface cracking, wear rate increased with increasing porosity content. The difference in friction and wear behavior between received Al A380M and Al 6061 is attributed to their hardness differences.
Effect of Surface Porosity on Tribological Properties of Sintered Pure Al and Al 6061  [PDF]
Avijit Sinha, Zoheir Farhat
Materials Sciences and Applications (MSA) , 2015, DOI: 10.4236/msa.2015.66059
Abstract: Due to light weight, high specific strength, high corrosion resistance and good heat transfer ability, aluminium alloys are becoming attractive for critical structural applications. These alloys can be manufactured using powder metallurgy techniques in which porosity is a common characteristic. The presence of pores is responsible for decreasing effective load bearing cross sectional area and inducing stress concentration sites for strain localization and damage, decreasing both strength and ductility. The present study aims to establish a better understanding of the relationship between surface porosity and corresponding wear behavior. In this study, porous specimens were produced using powder metallurgy technique and the extent of wear damage and the type of wear was investigated under low load range of 1.5 - 5 N against AISI 52100 bearing steel ball using a reciprocating ball-on-flat configuration and frequency of 10 Hz. Scanning electron microscopy of the wear tracks and wear debris was carried out to understand wear mechanisms. This study revealed that due to combined effect of high stress intensity and subsurface cracking, wear rate increases with increasing porosity content. The friction and wear behavior of pure Al and Al 6061 as a function of porosity content can be attributed to their hardness and corresponding wear mechanism.
A Short Report on Decompression Sickness Incidents in Andaman and Nicobar Islands  [PDF]
Sheeba Ahmed, Avijit Roy
Journal of Biosciences and Medicines (JBM) , 2016, DOI: 10.4236/jbm.2016.41012
Abstract: Objectives: Due to presence of extensively fascinating coral reef ecosystem in the continental shelf of Andaman and Nicobar Islands, people from all over the world visit these islands of India to indulge in recreational diving. An increased participation figure has also elevated the number of divers at risk for Decompression Sickness (DCS). Despite this, no scientific data are available on DCS incidents from India. Present study is aimed to evaluate the DCS incidents reported in these islands, treatment provided, and the outcome of the treatment. An attempt has also been made to calculate the approximate frequency of DCS in comparison to the participation figure. Methods: Study design is retrospective data analyses of a recompression chamber. Naval Diving Unit Port Blair has the only active decompression chamber available in the islands, and Govind Ballabh Pant Hospital Port Blair was used to collect information on DCS incidents that occurred during the mentioned period. Due to lack of authenticated generalized documents of divers’ health history and dive logs, the scanty information was gathered from the dive centres on the basis of personal interviews/communications among the SCUBA diving instructors. Results: A total of nine cases were reported during the span of last four and half years, and thus approximate frequency of DCS in Andamans was 0.2/10000 divers year. All of the patients recovered completely after receiving the Hyperbaric Oxygen Therapy (HBOT), with no residual symptoms. Conclusions: Incident rate of DCS in Andamans is lower than that in many other parts of the world; possible reason could be under-reporting of less severe DCS cases. During the study period, the number of DCS type II incidents presented for the treatment was higher than that of DCS type I incidents. HBOT proved a complete success in treating DCS cases in the island.

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