http://dspace.daffodilvarsity.edu.bd:8080/handle/123456789/1502 2026-04-05T17:26:53Z http://dspace.daffodilvarsity.edu.bd:8080/handle/20.500.11948/476 ROT-PROOFING OF JUTE FABRICS BY USING COPPER AMMONIUM CARBONATE SOLUTION Jafrin, Shamina; Uddin, Md. Kamal; Dilruba, F. A; Sultana, Dilruba, Nayer; Hossain, H.M. Zakir Jute hessian fabrics were treated with copper ammonium carbonate solution to increase its longevity. Two types of Hessians (sized and desized) were treated with various concentration of copper ammonium carbonate solution. To assess the effectiveness of copper ammonium carbonate solution as a rot proofing agent the liquor ratio, tensile strength, copper content and longevity of the treated fabrics were determined. The longevity of the treated jute fabrics were tested by exposing them to the environment in contact with wet soil as nursery pots for seedlings. The treated jute nursery pots exhibited a maximum longevity of fourteen months. 2008-07-01T00:00:00Z http://dspace.daffodilvarsity.edu.bd:8080/handle/20.500.11948/475 FIBER OPTIC COMMUNICATION LINK DESIGN Rana, Md. Masud; Islam, Md. Saiful In all-optical networks, traffic is carried end-to-end in the optical domain, without any intermediate optical-electrical-optical conversion. The promise of such networks is the elimination of a significant amount of electronic equipment, as well as added capabilities, such as the ability to transport any type of data format through the network. Fiber optic communications has been growing at a phenomenal pace over the past twenty years, so rapidly, in fact, that its impact is increasingly felt in nearly all aspects of communications technology. The design of such a system involves many aspects such as the type of source to be used (LED, LASER), the kind of fiber to be employed (multimode or single mode), and the detector (PIN or APD). This work emphasizes the basic requirements and design approaches of an optical fiber communication link. For designing such system the main concern is the optimization of cost, maximum link length and stability of performance characteristics. For a given bit rate, link length and typical bit error rate, the cost effective design is chosen here with software implementation. 2008-07-01T00:00:00Z http://dspace.daffodilvarsity.edu.bd:8080/handle/20.500.11948/474 EFFECTS OF SUBSTRATE SURFACE FINISH ON TRI- BOLOGICAL PERFORMANCE AND SURFACE TOPOGRA- PHY OF THERMALLY SPRAYED WC CERMET COATING Nuruzzaman, D. M.; Nakajima, A; Mawatari, T In this study, tribological characteristics and surface topographies of thermally sprayed WC-Cr-Ni cermet coating were investigated experimentally under lubricated rolling with sliding contact conditions. Hi-HVOF sprayed WC cermet coatings were deposited onto the axially ground, blasted and circumferentially ground roller specimens made of an induction hardened carbon steel. It was found that under a contact pressure 1.4 GPa, cermet coating showed a high durability and life of the coating was not influenced by the substrate surface finish. It was also found that coefficient of friction and surface temperature were hardly affected by the substrate surface finish. On the other hand, after running, surface topographical parameters such as skewness, kurtosis and surface roughness were significantly influenced depending on the substrate surface finish. Namely, after the running-in process, the skewness in the case of circumferentially ground substrate became much more negative than that in the case of axially ground or blasted substrate. In addition, kurtosis and surface roughness of the coated surface were much more influenced in the case of circumferentially ground substrate than that in the case of axially ground or blasted substrate. 2008-07-01T00:00:00Z http://dspace.daffodilvarsity.edu.bd:8080/handle/20.500.11948/473 COMPACT DUAL-BAND DUAL-POLARIZED MICROSTRIP PATCH ANTENNA FOR SYNTHETIC APERTURE RADAR Islam, Md. Fokhrul; Ali, M. A. Mohd; Majlis, B. Yeop; Misran, N There is an increasing demand for newer microwave and millimeter-wave systems to meet the emerging telecommunication challenges with respect to size, performance and cost. Microstrip antennas offer the advantages of thin profile, light weight, low cost, ease of fabrication and compatibility with integrated circuitry. This paper presents a coaxilly-fed single-layer compact microstrip patch antenna for achieving dual-polarized radiation suitable for applications in the IEEE Radar Band C and X. Simultaneous use of both frequencies should dramatically improve data collection and knowledge of the targets in an airborne synthetic aperture radar system. The designed antenna consists of three rectangular patches which are overlapped along their diagonals. The design and simulation of the antenna were performed using 3D full wave electromagnetic simulator IE3D. The antenna with a bandwidth of VSWR<2 reaches 154MHz (f0=6.83GHz) and 209MHz (f0=9.73GHz) was designed and simulated successfully. 2008-07-01T00:00:00Z