Vol. 09, Issue 2, July 2014

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    Comparative Performance Analysis Between IEEE 802.11 Dcf and Proposed Coopmac+
    (Daffodil International University, 2014-07-01) Islam, MD. Zahirul
    Medium Access Control (MAC) protocol is used to ensure that signals from different stations across the same channel collide. In this paper, a novel idea of user cooperation in wireless networks has been exploited to improve the performance of the IEEE 802.11 medium access control (MAC) protocol. The new MAC protocol leverages the multi-rate capability of IEEE 802.11b and allows the mobile stations (STA) far away from the access point (AP) to transmit at a higher rate by using an intermediate station as a relay. CoopMAC protocol is able to increase the throughput of the whole network and reduce the average packet delay. Moreover, CoopMAC also maintains backward compatibility with the legacy 802.11 protocol. The performance improvement is further evaluated by analysis and extensive simulations.
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    Effect of Deformation and Annealing Processing on Texture and Mechanical Properties of Aluminum Alloy AA1200
    (2014-07-01) Ayoola, Wasiu Ajibola; Oyetunji, Akinlabi
    The tensile strength, hardness, percentage elongation and grain size characteristics of aluminum alloy AA1200 were studied. The alloy samples were cold rolled prior to these tests with strain between 78 93, and thereafter annealed at temperatures lying between 200-450 "C and at holding times of between 2-6 hours. The results obtained showed that both the Ultimate Tensile Strength (UTS) and hardness increased with a higher degree of deformation prior to testing, but decreased as the annealing temperatures increased. The grain diameters on the other hand were seen to increase with increasing prior deformations and these fluctuate between 22.4 to 45 μm with an increase in the annealing temperatures.
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    Achievement of Nodules in Ductile Iron Having Sulphur Content Not Less Than 0.07% Weight
    (Daffodil International University, 2014-07-01) Oyetunji, A.; Omole, S.O.
    Scraps melt were analyzed with optical light emission spectrometer for chemical composition. The charge was prepared theoretically with carbon percent of 3.9 and silicon of between 2.1 and 2.8 percent after inoculation. 2 kg of CaCO3 (flux) was charged to aid removal of slag. The charges were heated to a tapping temperature of 1430° C. Temperature was monitored by inserting thermocouple in to the charges. The melt was desulphurised with 0.30 kg calcium carbide (CaC2) after the attainment of 1430°C. Three tappings were made tagged A, B and C into the prepared ladle via sandwich process. 3.5 %, 3.0 % and 2.0 % of ladle capacity (15 Kg) was the quantity of Mg used to treat melts A, B and C respectively. The treated melts were poured into the prepared sand moulds forming desired casting. The as-cast were analyzed again to determine its chemical compositions and found that carbon and silicon were not less than 2.0 and 1.0 % respectively. The casting was tested for hardness, tensile and micro structural evaluation. The microstructures revealed that as-cast tagged A and B formed nodular iron when etched with 2 % nital even with residual sulphur content of 0.075 % and 0.070% for A and B respectively. Cast produced from melt C revealed not a clear nodular cast iron. Emphasis is on casting A and B as we obtained nodules in A and B.
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    Effect of Optical Brightening Agent on Different Types of Fabrics
    (Daffodil International University, 2014-07-01) Iqbal, MD. Asib; Chowdhury, Dr. Nazmina; Jubayer, MD. Minhajj Uddin; Molla, Jannatul Bake; Hossain, S.M. Mahruf
    The knitted fabrics (single jersey, lycra single jersey, rib interlock, polo pique) were dyed with Optical Brightening Agent. From the overall comparison for different Shade% of different fabrics of Optical Brightening Agent, It was found that Color Index & Shade of Optical Brightening Agent is the most suitable dyeing used in industrial production. Optical Brightening Agent dyeing is probably the best described as an industrial art, having an assured future.
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    Numerical Study of Heat and Mass Transfer in a Transient Third Grade Fluid Flow in the Presence of Heat Source, Chemical Reaction and Thermal Radiation
    (Daffodil International University, 2014-07-01) Olajuwon, B.I.; Baoku, I.G.
    This paper investigates the combined influence of internal heat generation, suction, thermal radiation and chemical reaction of n order on an unsteady free convective heat and mass transfer flow of a chemically reactive third grade fluid over an infinite vertical porous plate with an oscillating temperature applied to the plate. The dimensionless partial differential equations governing this investigation are solved numerically by employing Crank-Nicolson finite difference scheme with modified Newton's iterative technique. Graphical results obtained for velocity, temperature and species concentration profiles are presented and discussed. The results show that the profiles are appreciably influenced by the suction, heat generation/absorption, thermal radiation, order of chemical reaction and viscoelastic parameters. The findings depict that the suction parameter has the influence of reducing velocity, temperature and species concentration fields. The fluid velocity increases as the value of the second grade viscoelastic parameter increases. Also, the third grade viscoelastic parameter has a significant effect on the velocity profiles. Finally, an increase in the thermal radiation parameter decreases the velocity distribution of flow field but it increases the temperature distribution
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    Exact Solution for the Tzitzeica-Dodd-Bullough Equation and Dodd-Bullough-Mikhailov Equation
    (Daffodil International University, 2014-07-01) Hossain, Mohammad Raquibul; Rahman, Md. Mijanoor; Das, Bimal Chandra
    Analytical technique Tanh method is applied in this work for finding solution of two nonlinear partial differential equations (NLPDEs) named as Tzitzeica-Dodd-Bullough (TDB) equation and Dodd-Bullough-Mikhailov (DBM) equation which contain exponential terms.
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    On Distributive Pseudo Complemented Lattice
    (Daffodil International University, 2014-07-01) Hasan, Md. Nazmul; Azad, Abul Kalam
    In lattice theory there are different classes of lattices known as variety of lattices. Distributive pseudo complemented lattice is one of the large variety. Throughout this paper We discuss pseudo complemented lattice. Pseudo complemented lattice were introduced by H. Lakser [2], [4], K.B.Lee [6]. In this paper we have studied pseudo complemented lattices and generalized Stone.
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    Unreliable Server Markovian Queue with Heterogeneous Arrival Under N-Policy
    (Daffodil International University, 2014-07-01) Chauhan, Deepa
    Model Description and Notations Present investigation deals with optimal management policy for Markovian queue with server breakdowns and vacations in which arrival occurs according to the state of the server. The customers arrive in Poisson fashion to get the service. The server may breakdown N λ(i=0,1,2,3) μ CC B Po(n) P1(n) P2(n) during the service and goes for repair immediately. By applying probability generating function technique queue length distribution is obtain for different states of the server. Further we determine the probability of empty system, expected number of units in the system. Following notations and probabilities are used through out the paper for formulating the model mathematically: Threshold level of queue length when server turns on Arrival rate of customers in various status Mean service rate of the server Mean break down rate of the server Mean repair rate of the server The probability of being n customers in the system and server is on vacation. The probability of being n customers in system when server is working The probability of being n customers in the system when server is found to be broken down. P1(n) The probability of being n customers in the system when server is under repair. 2. Governing Equations Steady state equations governing the model are given as follows: λo Po(0) = μPo (1) ZoPo(n) = 2o Po(n−1), 1 ≤ n ≤ N -1 (1) (2) λo Po(n) = λo Po (n-1), n> N (3) (λ1 + μ ÷ α)P1 (1) = μP (2) + BP3 (1) (4) (î, +u+α)P} + α)P(n) = ̧uP; (n + 1) + BP3 (n) + 2, P;
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    Date-Coconut Drink
    (Daffodil International University, 2014-01-01) Belewu, Moshood Adewale; Lawal, Abdulazees Muhammed; Abdulsalam, Kadijat; Belewu, Kafayat Yemisi; Belewu, Nosimot Oluwatobi
    This study evaluates the nutritional and sensory qualities of Date-Coconut drink that was prepared from a combination of Date palm juice and Coconut milk. The Treatments consist of a control (A) Date palm drink; 50% Date palm juice and 50% Coconut milk B; 25% Date palm juice and 75% Coconut milk C; 75% Date palm juice and 25% Coconut milk D. A completely randomized design model was used in the analysis of the physico- chemical and sensory qualities of the drink. The result revealed a delicious, sweet and sinks in the heart drink. The protein content was higher in the Coconut milk compared with Date juice. Conversely, the energy content of the Date juice was higher than Coconut milk. Additionally, the energy content was 332.10K.cal/g for the control (100% date palm juice);325.22k.cal/g Treatment B; 304.79k.cal/g Treatment C; and 306.82k.cal/g Treatment D. The protein content was 2.45% Treatment A; 3.73% Treatment B; 4.36% Treatment C and 3.08% Treatment D. The fat content was also highest for Treatment C>B>D>A in that order. Highly overall acceptability was recorded for Treatments B, C and D than A. Conclusively; the drink can be drank by all and sundry without and religious taboo.