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Search Results: 1 - 10 of 2603 matches for " Ashraful Islam "
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A Modified and Secured RSA Public Key Cryptosystem Based on “n” Prime Numbers  [PDF]
Muhammad Ariful Islam, Md. Ashraful Islam, Nazrul Islam, Boishakhi Shabnam
Journal of Computer and Communications (JCC) , 2018, DOI: 10.4236/jcc.2018.63006
Abstract: Cryptography is the study that provides security service. It concerns with confidentiality, integrity, and authentication. Public key cryptography provides an enormous revolution in the field of the cryptosystem. It uses two different keys where keys are related in such a way that, the public key can use to encrypt the message and private key can be used to decrypt the message. This paper proposed an enhanced and modified approach of RSA cryptosystem based on “n” distinct prime number. This existence of “n” prime number increases the difficulty of the factoring of the variable “N” which increases the complexity of the algorithm. In this approach, two different public key and private key generated from the large factor of the variable “N” and perform a double encryption-decryption operation which affords more security. Experiment on a set of a random number provided that the key generation time, analysis of variable “N”, encryption and decryption will take a long time compared to traditional RSA. Thus, this approach is more efficient, highly secured and not easily breakable.
Financial Volatility Forecasting by Nonlinear Support Vector Machine Heterogeneous Autoregressive Model: Evidence from Nikkei 225 Stock Index
Md. Ashraful Islam Khan
International Journal of Economics and Finance , 2011, DOI: 10.5539/ijef.v3n4p138
Abstract: Support vector machines (SVMs) are new semi-parametric tool for regression estimation. This paper introduced a new class of hybrid models, the nonlinear support vector machines heterogeneous autoregressive (SVM-HAR) models and aimed to compare the forecasting performance with the classical heterogeneous autoregressive (HAR) models to forecast financial volatilities. It was observed through empirical experiment that the newly proposed hybrid (SVM-HAR) models produced higher predicting ability than the classical HAR model.
Thickness, Distribution and Quality Assessment of Gopalganj-Madaripur Peat Deposits: A Case Study of Potential Economic Opportunities in Mid-Eastern Low-Lying Bangladesh  [PDF]
Mrinmoy Kumar Maitra, Md. Ashraful Islam, Md. Al Mamun
International Journal of Geosciences (IJG) , 2014, DOI: 10.4236/ijg.2014.59081

The present research work illustrates the extent, distribution and a generalized quality assessment of southern low-lying peat deposits in Madaripur and part of Gopalganj district that covers approximately 17,000 hectare areas. Based on the survey of 800 boreholes, drilled in this region at different times by several government and non-government organizations for the purposes of peat exploration and hydrogeological investigation, reveals that the study area is composed of a considerable amount of peat deposits in various localities among which the deposits at Baghia-Chanda beel in Madaripur and Gopalganj districts are the most remarkable. The average peat thickness (in-situ condition), studied during field investigation, is 6.5 feet for the upper peat deposits, overlying with an average of 3.5 feet of alluvium cover, followed by the lower peat layer of about 3 feet thick that begins at an average depth of 8 feet and separated by a thin bluish grey silty clay sediments from the upper one. The lower part of the study area, locally known as beels, is the most prospective region for peat, whereas the western part is less potential either having no peat intersection or minimal peat thickness. The overburden covers, on the other hand are inversely correlated with the peat thicknesses, i.e., thick overburden tend to correlate with thin peat deposits and the thickest peat intersections have no or minimal overburden. Due to the variation in bulk density and peat depth, this Holocene peat has an average of 59.10% carbon stock. Nitrogen levels, more than 3%, indicate that the peat developed from the decomposition of reeds, sedges, bushes and trunks of trees (higher in nitrogen) rather than either moss or grass (lower in nitrogen). Higher sulphur content (about 2.7%) reflected the influence of brackish environments where the formation of FeS2 took place in the roots of existing vegetation. The calorific values, about 1308.8 k-cal/kg (after 20% moisture reduction), suggest that the Gopalganj-Madaripur peat is a low grade fuel that can be used as an alternative energy source in the domestic and limited industrial purposes , to relatively expensive natural gas and

Intelligent Materials for Solar Cells
Surya Prakash Singh,Ashraful Islam
Advances in OptoElectronics , 2012, DOI: 10.1155/2012/919728
Intelligent Materials for Solar Cells
Surya Prakash Singh,Ashraful Islam
Advances in OptoElectronics , 2012, DOI: 10.1155/2012/919728
Hardware Virtualization Support In INTEL, AMD And IBM Power Processors
Kamanashis Biswas,Md. Ashraful Islam
Computer Science , 2009,
Abstract: At present, the mostly used and developed mechanism is hardware virtualization which provides a common platform to run multiple operating systems and applications in independent partitions. More precisely, it is all about resource virtualization as the term hardware virtualization is emphasized. In this paper, the aim is to find out the advantages and limitations of current virtualization techniques, analyze their cost and performance and also depict which forthcoming hardware virtualization techniques will able to provide efficient solutions for multiprocessor operating systems. This is done by making a methodical literature survey and statistical analysis of the benchmark reports provided by SPEC (Standard Performance Evaluation Corporation) and TPC (Transaction processing Performance Council). Finally, this paper presents the current aspects of hardware virtualization which will help the IT managers of the large organizations to take effective decision while choosing server with virtualization support. Again, the future works described in section 4 of this paper focuses on some real world challenges such as abstraction of multiple servers, language level virtualization, pre-virtualization etc. which may be point of great interest for the researchers.
Assessment of Physicochemical and Bacteriological Quality of Different Surface Water Samples of Tangail District, Bangladesh  [PDF]
Nasreen Jahan, Safaiatul Islam, Fatematuz Zuhura Evamoni, Md. Jakir Hossain, Sabiha Akter, Md. Ronzu Ahmmed, Md. Ashraful Islam, Shahin Mahmud
Advances in Microbiology (AiM) , 2017, DOI: 10.4236/aim.2017.711062
Surface water, a vital element of ecosystem must be hygienic, but unfortunately the pollution of this water is now an alarming problem. The present work deals with the assessment of physicochemical and bacteriological profile of several untreated surface water sources to ensure its suitability for using domestic purposes and drinking along with the impact of bacterial contaminated water on public health and antibiotic resistance pattern of these bacteria. The samples were collected from twenty sampling point (13 ponds, 4 lakes, 2 rivers and one canal) of Tangail District from January 2017 to July 2017. To understand the seasonal variation, water samples were measured in two month; February (dry season) and June (wet season). Most of the water sampling points were polluted by dumping of waste, cattle wash and were not suitable for the drinking or other domestic purposes. Obtained results showed that water of the study area is slightly alkaline, no remarkable variation in the temperature of the water in both seasons and DO of all the sampling station were lower than standard limit during February. The mean concentration (M.C.) of total Coliform were 4 × 1022 cfu/100ml and 4.5 × 1018 cfu/100ml at February and June respectively and all the sampling point were contaminated with fecal coliform. Other pathogenic bacteria, E. coli (M.C: 1.1 × 1011 cfu/100ml at February and M.C: 2.2 × 107 cfu/100ml at June), Salmonella spp. (M.C: 1.1 × 105 cfu/100ml at February and M.C: 3.4 × 105 cfu/100ml at June), Shigella spp. (M.C: 8 × 104 cfu/100ml at February and M.C: 3.4 × 107 cfu/100ml at June), Vibrio spp. (M.C: 8.6 × 105 cfu/100ml at February and M.C: 1.1 × 108 cfu/100ml at June) were isolated from several of the investigated water sources. The total counts of these pathogenic bacteria exceeded the acceptable limit during both season and also showed resistance against a broad range of commercially available antibiotics. People who were using these water frequently suffering from various water borne diseases. These untreated water sources pose a major threat to the public health and therefore with need for exigent intervention by government.
Synthesis and Application of New Ruthenium Complexes Containing β-Diketonato Ligands as Sensitizers for Nanocrystalline TiO2 Solar Cells
Ashraful Islam,Surya Prakash Singh,Liyuan Han
International Journal of Photoenergy , 2011, DOI: 10.1155/2011/204639
Abstract: Five heteroleptic ruthenium complexes having different β-diketonato ligands, [Ru(tctpy)(dppd)(NCS)] (1), [Ru(tctpy)(pd)(NCS)] (2), [Ru(tctpy)(tdd)(NCS)] (3), [Ru(tctpy)(mepd)(NCS)] (4), and [Ru(tctpy)(tmhd)(NCS)] (5), where tctpy = 4,4′,4′′-tricarboxy-2,2′:6′,2′′-terpyridine, pd = pentane-2,4-dione, mepd = 3-methylpentane-2,4-dione, tmhd = 2,2,6,6-tetramethylheptane-3,5-dione, tdd = tridecane-6,8-dione, and dppd = 1,3-diphenylpropane-1,3-dione, were synthesized and characterized. These heteroleptic complexes exhibit a broad metal-to-ligand charge transfer absorption band over the whole visible range extending up to 950?nm. The low-energy absorption bands and the E?(Ru3+/2+) oxidation potentials in these complexes could be tuned to about 15?nm and 110?mV, respectively, by choosing appropriate β-diketonate ligands. Molecular orbital calculation of complex 1 shows that the HOMO is localized on the NCS ligand and the LUMO is localized on the tctpy ligand, which is anchored to the TiO2 nanoparticles. The β-diketonato-ruthenium(II)-polypyridyl sensitizers, when anchored to nanocrystalline TiO2 films for light to electrical energy conversion in regenerative photoelectrochemical cells, achieve efficient sensitization to TiO2 electrodes with increasing activity in the order 5 < 4 < 3≈2 < 1. Under standard AM 1.5 sunlight, the complex 1 yielded a short-circuit photocurrent density of 16.7?mA/cm2, an open-circuit voltage of 0.58?V, and a fill factor of 0.64, corresponding to an overall conversion efficiency of 6.2%. A systematic tuning of HOMO energy level shows that an efficient sensitizer should possess a ground-state redox potential value of >+.53?V versus SCE. 1. Introduction Dye-sensitized solar cells (DSCs) have attracted a great deal of attention as one of the promising solar-to-electricity power conversion devices because of their high efficiency and their potential of low-cost production [1–6]. The properties of photosensitizers are one of the most important factors that influence the solar cell performance. Two outstanding Ru(II) polypyridyl sensitizers for nanocrystalline TiO2 solar cells so far reported are [Ru(dcbpy)2(NCS)2{(C4H9)4N}2] and [Ru(tctpy)(NCS)3{(C4H9)4N}3], where dcbpy is 4,4′-dicarboxy-2,2′-bipyridine and tctpy is 4,4′,4′′-tricarboxy-2,2′:6′,2′′-terpyridine, yielding solar to electric power conversion efficiency of over 11% under standard AM 1.5 condition [5, 7–9]. To get an efficient solar cell performance, the sensitizer should fulfill several requirements, including that (i) the dye’s absorption spectrum should overlap with the solar
Fast Algorithm of A 64-bit Decimal Logarithmic Converter
Ramin Tajallipour,Md. Ashraful Islam,Khan Wahid
Journal of Computers , 2010, DOI: 10.4304/jcp.5.12.1847-1855
Abstract: The paper presents an efficient algorithm to compute base-10 logarithm of a decimal number. The algorithm uses a 64-bit floating-point arithmetic, and is based on a digit-by-digit iterative computation that does not require look-up tables, curve fitting, decimal-binary conversion, or division operations. It is the first FPGA prototype of its kind that uses a 64-bit (decimal 16-digit) precision. Two numerical examples have been presented for the purpose of illustration. The algorithm produces very accurate result with a maximum absolute error of 3.53x10-14. The architecture is pipelined and implemented on to the Xilinx Virtex2p FPGA. It costs 6,752 logic cells, outputs at a minimum rate of 51 mega-samples/sec, and consumes 125.7 mW of power. The scheme is very suitable for timing and accuracy critical applications and compliant with the IEEE754-2008 standard (decimal64 format).
Dissolution study of Spironolactone by using solid dispersion technique
Irwin Dewan,SM Ashraful Islam,Mohammad Shahriar
Stamford Journal of Pharmaceutical Sciences , 2011,
Abstract: The main objective of the current study was to formulate poorly water soluble drug Spirinolactone by using solid dispersion technique in order to achieve a better dissolution rate which would further help in enhancing oral bioavailability. Solid dispersions were prepared using two methods; solvent method and fusion method. Solid dispersion was prepared by using polymers, such as Hydroxy propylymethyl cellulose (HPMC 6cp), Hydroxy propyl cellulose (HPC), Sodium carboxymethylcellulose (Na-CMC), Povidone K12, Povidone K30, Poloxamer 407. Solid dispersions containing Spironolactone with HPC (96.81%), HPMC 6cp (93.05%), Poloxamer 407 (90.84%) and Na-CMC (89.93%) provided higher release rate than the release rate of solid dispersion containing only Spironolactone (35.27%), and Spironolactone with Povidone K12 (76.17%), Povidone K30 (67.92%). So the present study revealed that the solid dispersion may be an ideal means of drug delivery system for poorly water soluble drugs. Further study in this field was required to establish these drug delivery systems so that in future it can be used effectively in commercial basis.
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