Pilot Based Channel Estimation in IEEE 802 16a OFDM System

1　Introdution　IEEE 802 16[1] is a specification for fixed broadbandwireless Metropolitan Access Networks (MAN). The stan dard is expected to bring low cost and more bandwidth prod ucts for broadband wireless access in the next years. Thisstandard specifies the physical (PHY) and Medium AccessControl layer (MAC) of the air interface of interoperablepoint to multipoint and optional Mesh topology broadbandwireless access system. The specification enables access todata, …     

The investigation of electrodeposited Cu2O/ITO layers by chronocoulometry process: effect of electrical potential

The thin films of Cu₂O are deposited by electrodeposition technique onto indium tin oxide (ITO)-coated glass substrate at different potentials. The precursor is an aqueous solution which contains respectively 0.05 M of CuSO₄ and citric acid at kept temperature of 60℃ and the applied potential varies within the {-0.4 V,-0.7 V} SCE range. Based on the chronocoulometry (CC) process, the electrochemical, structural and optical parameters are determined. We measured the current as function of potential within the {-0.4 V,-0.7 V} range and the higher current is found to be within the {-0.7 V,-0.3 V} band. The grain sizes are of 12.12 nm and 35.47 nm according to (110) and (221) orientations respectively. The high textural coefficient of 0.943 is recorded for the potential-0.7 V. The transmittance of 72.25 %, within the visible band, is obtained for the as-grown layer at-0.4 V and the band gap is found to be 2.2 eV for the electrodeposition potential of-0.7 V.     

The Second Order PMD in Optic Fiber and Compensation Experiment

1　Introduction　Inhigh speed /long distanceopticalfibertransmissionsystem ,PMDisoneofthemainfactorslimitingthebitrateandthetransmissiondistance ,becomingespeciallyimportantasthebitrateincreaseshigherthan 2 5Gb/s .TheinstantaneousPMDoftransmissionlineischangingfromtimetotimeandfromfrequencytofre quencyrandomly .InfrequencydomainPMDcanbeex pressedbytheTaylorexpansionatcenterfrequencyanddividedintofirstorder ,secondorder ,…ofwhichhigh erthansecondareallcalledhighorderPMD[1] .Fromfrequenc…     

The Integrated Control-Mechanism in ATM-Based Networks

1 Introduction Network survivability has become a critical issue in telecommunication networks owing to the increase of social dependence on communication systems and the growing importance of information. Fast restoration from a network failure has been …     

THE OPTIMAL DESIGN BASED ON RELIABILITY OF WATER DISTRIBUTION SYSTEM BY LINEAR MODEL

In this paper, a new technique are developed for optimal design of water distribution system besed on reliability. It applies a linear programming algorithm to the optimal design based on reliability. Within a small optimal search step range,the objective function and constraints can be expressed in the first order Taylor-expanding form,and three sub-models (a steady-state simulation model, a reliability model and a linear optimization model) are linked each in optimal searches. Thus, a traditional non linear problem can be solved by a linear model, the computing burden is significantly decreased. Therefore, the linear optimal model developed by the paper has more practical significance.     

TWO-DIMENSIONAL SIMULATION OF FLOWS IN PLANE-WALL DIFFUSERS

A numerical model has been developed for computing turbulent flow in plane-walldiffuser.The model solves the weakly compressible flow equations with the application of theSmagorinsky's subgrid-scale turbulence model and the boundary conditions of partial slip and noslip at the solid wall.Application examples include two-dimensional calculations of unstalled andstalled flows in diffusers of small diverging angle,as well as transitory stall flow in a symmetricdiffuser of 16°total angle.For the unstalled and stalled flows,the calculated pressure recoveryand velocity profile are compared with experimental data.For the transitory stall flow,the com-putational result shows the unsteady flow features including the vortex shedding and stallwashout phenomena that have been experimentally observed.     

SOLUTE TRANSPORT THROUGH THE VADOSE ZONE:FIELD STUDIES

ＳＯＬＵＴＥＴＲＡＮＳＰＯＲＴＴＨＲＯＵＧＨＴＨＥＶＡＤＯＳＥＺＯＮＥ：ＦＩＥＬＤＳＴＵＤＩＥＳ￥ＹｅＺｉ－ｔｏｎｇ（ＤｅｐａｒｔｍｅｎｔｏｆＨｙｄｒａｕｌｉｃＥｎｇ．，ＷｕｈａｎＵｎｉｖｅｒｓｉｔｙｏｆＨｙｄｒａｕｌｉｃａｎｄＥｌｅｃｔｒｉｃＥｎｇ...     

SECONDARY INSTABILITY WITH RESPECT TO SPATIAL GROWING THREE－DIMENSIONAL SUBHARMONIC DISTURBANCES IN BOUNDARY LAYER FLOW WITH SUCTION

ＳＥＣＯＮＤＡＲＹＩＮＳＴＡＢＩＬＩＴＹＷＩＴＨＲＥＳＰＥＣＴＴＯＳＰＡＴＩＡＬＧＲＯＷＩＮＧＴＨＲＥＥ－ＤＩＭＥＮＳＩＯＮＡＬＳＵＢＨＡＲＭＯＮＩＣＤＩＳＴＵＲＢＡＮＣＥＳＩＮＢＯＵＮＤＡＲＹＬＡＹＥＲＦＬＯＷＷＩＴＨＳＵＣＴＩＯＮ￥ＺｈａｏＧｅｎ...     

墨西哥孔乔斯河流域水权转让问题的分析

墨西哥于1992年颁布的<国家水法>允许进行水权转让,但直到目前,水权转让工作并没有全面展开,有限数量的水权转让仅限于灌区层面之内.作者评估了墨西哥水权转让政策,并且提出了根据当前政策的可选方案,建议水市场的指导原则要遵从效益与公平.研究的目标是格兰德河的重要支流流域孔乔斯(Conchos)河流域,但同时也分析了墨西哥...     

生物质用于焦炭和烧结生产的实验室评价

生物质作为碳可供选择的环保替代燃料,用其进行炼焦和炼铁是一个非常好的选择,因此,应该积极调查、研究如何采取不同的方法利用生物质,以减少硫化物、氮氧化物、二氧化碳的排放和可能的成本投入。对生物质在炼焦生产与烧结生产中的实用性在独立的试验中进行评估。生物质对炼焦生产的实用性研究如下:将1%～5%的木质生物质或是焙烤(轻度热解)的木质生物质作为部分高挥发性煤的替代物添加至配合煤中,在实验室焦炉中进行碳化试验。试验结果表明,当把粉碎的生物质加入到配合煤后,焦化压力显著降低,同时焦炭的硫含量下降,但是焦炭的高温强度和力学性能亦有轻微下降,但这种实测强度的降低需要进一步的研究。另外,在一系列独立试验中,通过利用生物质(分别是锯末、粉碎的玉米芯、树皮、木炭等)作为烧结用粉焦的替代燃料在实验室烧结锅进行评估。试验中,燃料用10%、20%、30%、40%的生物质代替。试验结果显示,烧结混合料的堆密度和烧结时间都有下降,添加了生物质的烧结矿质量没有显著恶化。这些初步的试验表明,在实际的炼焦与炼铁生产中生物质很有可能作为一种可再生能源替代部分传统的化石燃料。为了某种特定应用而进行产品优化则需要额外试验。