Galaxy (Dhaka): The MIST Journal

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    DESIGN OF A MICROSTRIP PATCH ANTENNA IN A SILICON SUBSTRATE USING HFSS
    (R&D Wing, MIST, 2010-02) Nabila Nikhat, Shamma; Rashid, Rimi; Rayhan, Sajeeb; Saha, Pran Kanai
    The aim of this paper is to design a compact microstrip patch antenna for use in wireless/cellular devices. A typical cellular phone measures about 14.5 cm by 4.5 cm. Hence the antenna designed must be able to fit in such a cellular phone. A compact microstrip patch antenna has been successfully designed having a center frequency of 1.9 GHz. The ground plane dimensions for the patch antenna have been designed to be 31 mm by 40 mm and the patch dimensions are 22 mm by 31 mm. This is designed and simulated in High Frequency Structure Simulator (HFSS-9.2) of Ansoft Corporation.
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    AN EXPERIMENTAL INVESTIGATION OF WIND LOAD ON TALL BUILDINGS WITH HEXAGONAL CROSS-SECTION
    (R&D Wing, MIST, 2010-02) Sultana, Kaniz Ronak; Chandra Mandal, Dr. Amalesh; Shameem Mahmood Ebna Hai, Bhuiyan
    An experimental investigation of surface static pressure distributions on hexagonal cylinder was conducted. The study was performed on both the single cylinder and the group consisting of two cylinders, one in the upstream and another in the downstream side. The test was conducted in an open circuit wind tunnel at a Reynolds number of 4.13 x 104 based on the face width of the cylinder across the flow direction in a uniform flow of velocity 13.2 m/s. The study was done on the single cylinder at various angles of attack from 00 to 500 at a step of 100. The surface pressure distributions were measured with the help of an inclined manometer. Then the group of two cylinders was taken into consideration for the study and the surface static pressures were measured for various inter-spacing of 1D, 2D, 3D, 4D, 6D and 8 D, D being the width of the cylinder across the flow direction. In each case the wind velocity was kept constant at 13.2 m/s. The pressure coefficients were calculated from the measured values of the surface static pressure distributions on the cylinder. Then the drag and lift coefficients were obtained from the pressure coefficients by the numerical integration method. It was observed that the drag coefficients become remarkably smaller compared to those for a sharp-edged square cylinder. It was also observed that at various angles of attack, the values of the lift coefficients were insignificant compared to those for a sharp-edged square cylinder. It can be further concluded that the hexagonal cylinder produces significantly low values of drag and lift forces and they approach to those of the cylinder with circular cross-section.
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    DERIVATIVES FOR CAPITAL MARKET EFFICIENCY
    (R&D Wing, MIST, 2010-02) Jahan, Masud; Hossain, Md. Moulude; Jaman, Md.
    Derivative contracts transfer risk, especially price risk, to those who are able and willing to bear it. How they transfer risk is complicated and frequently misinterpreted. Derivatives have also been associated with some spectacular financial failures and with dubious financial reporting. This paper will discuss the role of derivative products in capital flows, especially in providing a means of both reducing and enhancing market risks associated with given net flows. It will emphasize how derivatives can be used to evade risk-control or prudential regulation, circumvent capital controls, drive the dynamics of currency instabilities, and obscure true risk positions and thereby undermine the usefulness of balance of payments capital account categories. Financial derivatives (credit default swaps, options, etc) are screwing over the economy because too much money is being poured into the invisible (derivatives) market. This probably undervalues the prices of the underlying goods/assets/etc in the real market (instead, investors should just simply buy the stocks, etc and the increased demand would drive up the stock price and it would make everyone happy). All these derivatives may contribute to risk… it may encourage people to take on unreasonable risk and could lead to drastic market volatility.
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    WIMAX SECURITY ANALYSIS AND ENHANCEMENT
    (R&D Wing, MIST, 2010-02) Kowsar, Mir Md. Saki; Rahman, Muhammad Sakibur
    The importance of IEEE 802.16, Worldwide Interoperability for Microwave Access (WiMAX) is growing and will compete with technologies such as 3G. The acceptance and adoption of technologies also depend on security. Therefore, this article shows security vulnerabilities found in WiMAX and gives possible solutions to eliminate them. We find the initial network procedure is not effectively secured that makes man-in-the-middle attack possible. Focusing on this attack, we propose Diffie-Hellman (DH) key exchange protocol to enhance the security level during network initialization. We modify DH key exchange protocol to fit it into mobile WiMAX network as well as to eliminate existing weakness in original DH key exchange protocol. Finally we found that the proposed algorithm shows 2.5 times better performance in comparison with existing systems.
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    A STUDY ON VEHICLE INDUCED NOISE POLLUTION USING GIS IN DHAKA CITY
    (R&D Wing, MIST, 2010-02) Bint Ayaz, Sayeeda
    In this study, overall roadside environment of selected locations in Dhaka city has been focused concentrating on degradation of the environment through noise. For the study of noise pollution, noise level was measured at some severely exposed as well as sensitive locations of the city. It is inferred that average level of noise at roadside exceeds the allowable limit to a great extent at all the locations and sensitive locations like hospital, school, mosque etc. The deviation from standard limit was found high. The collected data were analyzed by GIS symbological analysis & plotting several graphs and comparisons were made with acceptable level of noise provided by Department of Environment (DOE), Bangladesh (ECR, 1997). Comparison showed that noise pollution at all the locations is higher than the acceptable limit. Several measures were proposed to reduce the level of noise pollution in the city as well as stabilizing the existing condition which include enhancing mass consciousness, construction of noise barriers and implementation of proper monitoring system to reduce traffic noise.
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    A SCHEME FOR GAIN FLATTEN OF FIBRE RAMAN AMPLIFIER FOR WDM TRANSMISSION SYSTEMS
    (R&D Wing, MIST, 2010-02) Hossain, Md. Azmal; Ahmed, Feroz; Rahman, Mohammad Shamsur
    The most attractive feature of Fiber Raman amplifiers are extremely large gain bandwidth and play an important role in wavelength division multiplexing (WDM) systems. However, the weakness of Raman amplifier is that the gain spectrum is flat for very small narrowband. So, it is necessary to flatten the Raman gain profile to achieve the desire performance for the WDM systems. This paper has proposed an extrinsic gain flattening technique for WDM transmission systems using Polarization-diversity Loop Filter (PDLF). With this technique, an equalize bandwidth of 114nm (1536nm – 1650nm) can be achieved with a gain ripple of 0.5dB.
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    STUDY ON MECHANICAL PRODUCT BASED SMALL AND MEDIUM ENTERPRISES OF BANGLADESH AND IMPROVEMENT OF A SELECTED PRODUCT
    (R&D Wing, MIST, 2010-02) Abdus Salam, Gp Capt Md; Shameem Mahmood Ebna Hai, Bhuiyan
    Small and medium Enterprises (SME) plays a vital role in the economic development of country especially in the developing countries like Bangladesh. Keeping this concept an attempt has been made to survey the SME products of Bangladesh, study and improve the qualitative performance of a selected mechanical Engineering related SME product. The most difficult part of the project was the survey portion as related project/ research paper in this field is not relatively available. With almost effort lot of information has been gathered related to different range of SME products and related factors. For study and improvement of qualitative performance of cylinder and piston used in Conchi-4 R170 engine has been selected. On study it is formed that the local product quality effort was made for qualitative improvement but due to time constraint that could not be done. In subsequent projects steps may be taken for qualitative improvement using this analysis.
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    ELECTRICAL ENERGY FORECASTING - A PROBABILISTIC APPROACH
    (R&D Wing, MIST, 2010-02) Uddin, Col Moin
    Energy demand forecasting is essentially required for the optimal use of energy resources of a country. This paper presents a methodology to forecast the electrical energy demand of a power system. The methodology is based on the forecasting of hourly demand. A relationship is developed among the forecasted annual/seasonal average hourly load and the probabilistic laws of load ratios to forecast the hourly load. The proposed methodology is validated by applying it to a power system. The methodology is useful for long term hourly load forecasting and also for the forecast of electric energy requirement of a country.
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    EFFECT OF CRUSHING METHODS OF VOLAGONJ STONE ON STRENGTH OF CONCRETE
    (R&D Wing, MIST, 2010-02) Shamsuddoha, M.; Billah, A.M.; Islam, A.B.M.T.; H.R. Kamal, Brig Gen
    A comparative study was carried on Hand Crushed and Machine Crushed Volagonj stone (major rock of Bangladesh) graded between 1 in [25 mm] to 0.5 in [12.5 mm]. Stone crushed by both hand and machine were tested for abrasion value, crushing value, flakiness index, and elongation index. These stone groups were used to prepare concrete cylinders (6 in. [150 mm] diameter and 12 in. [300 mm] height) for W/C ratio ranging from 0.45 to 0.60. Hand crushed stone was showing abrasion and crushing value more than machine crushed stone by about three and one percent respectively. Machine crushed stone is flakier and elongated than hand crushed stone by about six and two percent respectively. Cylinders made with hand crushed stone showed more compressive strength than machine crushed stone with an exception of early age (1 day) and high W/C ratio (0.60). This phenomenon suggest low strength of cement matrix-aggregate interface bond firstly due to low maturity and secondly due to low strength of cement matrix to bond with aggregate.
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    Estimated damages and casulalties in Dhaka city due to possible earthquake
    (Research and Development Wing, MIST, 2010-02) Rahman, Col Md Gazi Ferooz; Ansary, Dr. Mehedi Ahmed
    Earthquake risk at any location depends on the seismic hazard as well as the vulnerability of its structures. For old city like Dhaka, a larger portion of building is very old and consequently vulnerable and local construction practice also has a strong bearing on the seismic vulnerability. Dhaka City Corporation, which has a population of about 6 million in 90 wards. Most of the wards are in older part of the city, which has a population density exceeding 60,000 per square kilometres. For the city, a building inventory of 3668 buildings from eight wards was compiled. Together with BBS data, data from Geological of Bangladesh (GSB) and Dhaka City Corporation, this building inventory is used in different analysis purpose. A soil database of 253 boreholes is developed which are used to develop site amplification and soil liquefaction potentials assessment of the city. Three past historical earthquakes are used as scenario events namely 1885 Bengal Earthquake, 1897 Great Indian Earthquake and 1918 Srimongal Earthquake. Earthquake damage of buildings of different typologies was estimated by using fragility curves proposed by Arya. Human casualty (death and injury) was estimated by a morbidity model proposed by Coburn. If the 1897 Great Indian Earthquake occurs again, on an average 28% of buildings will be estimated to be damaged and 3.7% of total population will be dead and injured.