Volume: 7
Number: 2
December 2009

To see an article directly, click its Title. To see abstract, click its [Abstract] link.

• Parallel Miniature Heat Pipes: The Silent Way to Manage Desktop Thermal Problems
  Chowdhurv Md. Feroz and Ahmed lmtiaz Uddin.
  Abstract PDF
  Parallel Miniature Heat Pipes: The Silent Way to Manage Desktop Thermal Problems
  Chowdhurv Md. Feroz and Ahmed lmtiaz Uddin.

  Abstract

  Heat transfer performance of parallel miniature heat pipes MHP) of 2.8 mm ID used for cooling desktop computer processor is presented in this paper. In cooling desktop processors, MHP consists of six single tube heat pipes connected by a copper block st the evaporator section and fifteen parallel copper sheets used as external fins at the condenser section. Ethanol is used as working fluid. The copper block is placed above the heat source (on the top of the processor) and the condenser section is provided with external fins perpendicular to the MHP. Experimental results show that the maximum and steady state temperature of the processor surface has been reduced significantly by using MHP instead of conventional cooling fan. Addition of fan at the condenser section shows much low and steady state temperature of the processor surface.
• Outage Analysis of Multi-hop Parallel Relay Networks
  B. Barua, M.Z.I. Sarkar and Nipu Kumar Das
  Abstract PDF
  Outage Analysis of Multi-hop Parallel Relay Networks
  B. Barua, M.Z.I. Sarkar and Nipu Kumar Das

  Abstract

  In this paper, we consider a multi-hop parallel relay network in which relays cooperate with its next relay in a series fashion, and the cooperation between two relays exists if they are not in outage. For this network, we derive the generalized expression of outage probability in terms of number of relays in a cluster. We also present the simulation results to find the relationship of outage probability with the number of hops and the relay nodes in a stage.
• Performance Enhancement in Media Access Control (MAC) layer protocol on Wireless Sensor Network
  Abu Raihan Mostofa Kamal, M. Aminul Islam, Md. Khaled-Ur-Rahman and Md. Zubairul Islam
  Abstract PDF
  Performance Enhancement in Media Access Control (MAC) layer protocol on Wireless Sensor Network
  Abu Raihan Mostofa Kamal, M. Aminul Islam, Md. Khaled-Ur-Rahman and Md. Zubairul Islam

  Abstract

  The Media Access Control (MAC) Iayer is a part of the data link layer specified in the seven layer OSI model (layer 2). It provides addressing and channel access control mechanisms that make it possible for several terminals or network nodes to communicate within a multipoint network The MAC sub- layer acts as an interface between the Logical Link Control (LLC) sub-layer and the network's physical layer. It provides an addressing mechanism called physical address or MAC address that is described by MAC address protocol or MAC protocol. An efficient Medium Access Control (MAC) protocol is very important for the performance of a wireless Sensor Network (WSN), especially in terms of energy consumption. There are different existing MAC protocols for the wireless sensor network ll/e have analyzed those protocols and found the issues on which performance varies. Then we have tried to eliminate some of the demerits and finally proposed a new MAC protocol that performs better considering some attributes.
• Object-Oriented Hydro Information System (OHIS) for the Estimation and Visualization of Vegetation Water Content
  S. Shams and J. Huang
  Abstract PDF
  Object-Oriented Hydro Information System (OHIS) for the Estimation and Visualization of Vegetation Water Content
  S. Shams and J. Huang

  Abstract

  Vegetation indices are important parameters in remote sensing. In many scientific investigations, successful vegetation properties estimation heavily relies on proper use of vegetation indices. Vegetation water content (VWC) is one of the most important biophysical properties of vegetation that can be used in hydrological modeling, agricultural planning, forestry administration and even the climate change studies. However, to estimate VWC using remote sensing satellites data has been heavily relying on vendor dependent specific software rather than open source software. Hence, the paper highlights the development of a java-based open source information system integrated with MySQL Database to store, retrieve, query and analyze remote sensing data to estimate VWC. The hydro information system is platform independent, which enhances its great potential to be accessed from any computers, anywhere through the web browser. Taking its advantages, the system evaluated the performance of various vegetation indices in VWC estimation systematically. The short-wave infrared (SWIR) bands were proved to be superior to the other bands when corn and soybeans VWC are concerned under the similar environmental condition of SMEX02 (Soil Moisture Experiment in 2002).
• A Study of Performance of a Box-type Solar Cooker with and without Booster Reflectors
  A. K. M.Iqbal Hussain
  Abstract PDF
  A Study of Performance of a Box-type Solar Cooker with and without Booster Reflectors
  A. K. M.Iqbal Hussain

  Abstract

  Every year millions of tones of biomass and fossil fuels are burnt to cook foods around the world. As reserves of these fuels are limited, attention must be given to utilize solar energy for cooking purposes. Although concentrating solar cookers can produce high temperatures, its usage is restricted hecause of high costs and complexity in handling. On the other hand, box-type solar cookers using conventional flat-plate collectors are relatively cheap and easier in handling. In this research work, a box-type cooker was constructed and experiments were carried out in the IUT Campus during the month of April when the sky remains fairly clear. Modifications of the simple cooker are done by adding plane booster reflectors on three sides of the cooker box Experiments are carried out with both the simple and the modified types over several days from 10:00 a.m. to 4:00 p.m. Relevant data e.g. half-hourly and cumulative available solar radiation intensity, temperature of two glass cover plates, temperatures of heated water, ambient air temperature and its average speed are recorded every hour. From the experimental data, performance parameters, such as heat loss coefficients, useful heat rates and the cooker collector efficiencies at different absorber plate temperatures at different hours of the day are computed using relevant equations and have been presented in graphical forms. Results show that the cooker with booster reflectors can heat water to about 93°C which is close to normal cooking temperature of 100°C for added water in foods whereas, the cooker without reflectors can heat the water to about 65°C. Hence, even preheating of the food by the cooker will require a small amount of additional supplementary heat which can be produced by burning biomass or conventional fossil fuel in order to accomplish the cooking process.