Analytical evaluation of average bit error rate for the land mobile satellite channel

An analytical solution is presented showing the average bit error probability for the land mobile satellite channel. The channel is modelled as Rice and Rayleigh—lognormal fading. Modulation schemes under consideration include differentially detected PSK and non-coherently detected FSK. Results indicate that the receiver performance is highly dominated by the time share of shadowing. The ratio of the BERs in shadowed and unshadowed areas of typical measured channels and an operating point assumed to be at E_s/N_o = 10 dB is of the order of 10^?2.     

Integrated Approach to Determining Postreclamation Coastlines

An integrated approach is presented for determining the harmonized optimal coastline from given options for large-scale coastal reclamation. The approach incorporates results from hydrodynamic, sediment transport, and water quality models and ecological impact considerations. These models predict reclamation impact on tidal flow, sediment deposition and erosion, and water quality under different scenarios. The impact on sensitive coastal ecosystems is considered indirectly in terms of the qualitative relationship to results from the sediment transport model. The analytical hierarchy process method is applied to determine the weights of various control factors and to integrate the model predictions. A sensitivity analysis is made to assess the effect on the final results of modeling errors and uncertainty in the weights assigned, and thus to enhance the reliability of decision making. Although the methodology given herein emphasizes reclamation in a bay with multifold functions, the procedure is potentially applicable to most coastal reclamation projects, except single-option schemes. An application to Deep Bay coastline is described in the companion paper.     

Simulation of water and nitrogen dynamics in soils during wastewater applications by using a finite-element model

A mathematical model was developed to simulate water movement, mass transport, and nitrogen transformations in soils during wastewater applications. The model is one-dimensional and based on the Galerkin finite-element method. The submodel of mass transport of nitrogen incorporates the convection-dispersion processes of ammonium and nitrate nitrogen, nitrification, denitrification, ammonium exchange and uptake of ammonium and nitrate ions. The accuracy and validity of the proposed model was examined by comparison with an explicit-implicit finite-difference model results. The model was used for simulation of water and nitrogen dynamics during wastewater application in homogeneous and multi-layered soils under different N concentration, rate, duration and scheduling of application.     

Environmental Monitoring of Spatio-temporal Changes Using Remote Sensing and GIS in a Mediterranean Wetland of Northern Greece

Loss and degradation of terrestrial and aquatic habitats and degraded water quality are major environmental concerns worldwide. Especially wetlands are sensitive ecosystems that are subject to stress from human activities. Remote sensing techniques have been primarily used to generate information on land cover/use changes. Geographical Information Systems (GIS) and remote sensing can be used to provide a rapid or a large-scale understanding of lake change and in developing lake management strategies. The principal objectives of this study are to monitor and assess the spatial and temporal changes in land cover/use by using GIS, and to determine the main environmental factors affecting these changes. This paper presents a case study for the application of integrated remote sensing and GIS data for the classification and monitoring of the spatial and temporal changes in land use types. The study was conducted in a small natural wetland of Lake Cheimaditida, located in the East Mediterranean region of Northern Greece. Data analysis was conducted using GIS software. During the past several decades Lake Cheimaditida wetland has been influenced by many anthropogenic activities. The variables chosen for the assessment included condition of wetland and lake areas, present extent of wetlands relative to historic area, cover of natural habitat, wetland disturbances, etc. These variables address catchments properties that are important for maintaining and improving wetland habitats and water quality and assessment of trends useful for environmental monitoring. Land cover/land use patterns were assessed and compared using aerial photographs taken in 1945, 1969, 1982, and 1996. Over this period, reed beds enormously increased by 1,655.19%, while open-water areas and peat lands decreased by 74.05 and 99.5%, respectively. The significance of the changes in land cover distribution within the Lake Cheimaditida wetland are discussed in relation to the historical pattern of reed beds colonization, the importance of Phragmites australis in the process and the implications for strategic management of freshwater wetland resources.     

涑水河下游洼地水资源利用方式的探讨

涑水河下游洼地理构造特殊，在该区内搞水利建设必须重视其特殊性。本文着重从水资源利用方式上，对减少农田旱、涝、洪、碱等灾害谈了一些看法。     

浅析大同市区地下水开采与环境地质问题

大同市平原区地下水历年严重超采 ,造成了地下水持续大面积大幅度下降 ,从而形成了总面积 93 .6km2 的 4个地下水降落漏斗 ,最大漏斗区中心水位下降达 30m ,随之引发了大面积地面沉降 ,地裂缝出现并不断发展 ,总长度达 18.8km。另外 ,由于废污水的排放、引污灌溉、工业生活废渣的堆积 ,造成地下水质污染 ,使得水环境地质状况进一步恶化     

东海某气田FHT构造PH下层系沉积相研究

在对西湖凹陷FHT构造岩心、钻井及分析化验资料综合研究的基础上,运用层序地层学、沉积学和测井地质学原理,通过大量的基础研究,克服了海上井少、资料不全的困难,识别了西湖凹陷PH组下层系沉积环境、沉积特征。经过分析研究,认为PH组下层系P8、P9、P10、P11沉积环境为半封闭海湾中的泻湖潮坪沉积。在平面上,预测了砂体的平面展布特征,分析了其在平面上的演化规律。纵向上,从P11到P8层,砂体逐渐向凹陷的西南扩展,规模也有所扩大,总体上反映为海进的沉积特征。     

利用卫星遥感影像进行城市土地利用动态监测

随着航天遥感分辨率的提高,利用卫星遥感影像代替航空遥感数据进行城市土地利用动态监测已成为可能,本文从原理、方法和实践上论证了其可行性。     

秦牧散文的文体改造与源流

秦牧作为17年时期重要的散文家之一，其成绩是与他所自觉进行的文体改造分不开的。秦牧的身份和处境使得他的文体改造颇为顺利。秦牧17年文体改造体现在特写强调、抒情风味、辨证色彩三个方面，这与当时的文风密切相关。秦牧的文体改造延续了学者散文的文脉，也印证了文体改造在文学史上的积极意义。     

Traffic analysis zone level crash estimation models based on land use characteristics

The objective of this paper is to develop crash estimation models at traffic analysis zone (TAZ) level as a function of land use characteristics. Crash data and land use data for the City of Charlotte, Mecklenburg County, North Carolina were used to illustrate the development of TAZ level crash estimation models. Negative binomial count models (with log-link) were developed as data was observed to be over-dispersed. Demographic/socio-economic characteristics such as population, the number of household units and employment, traffic indicators such as trip productions and attractions, and, on-network characteristics such as center-lane miles by speed limit were observed to be correlated to land use characteristics, and, hence were not considered in the development of TAZ level crash estimation models. Urban residential commercial, rural district and mixed use district land use variables were observed to be correlated to other land use variables and were also not considered in the development of the models. Results obtained indicate that land use characteristics such as mixed use development, urban residential, single-family residential, multi-family residential, business and, office district are strongly associated and play a statistically significant role in estimating TAZ level crashes. The coefficient for single-family residential area was observed to be negative, indicating a decrease in the number of crashes with an increase in single-family residential area. Models were also developed to estimate these crashes by severity (injury and property damage only crashes). The outcomes can be used in safety conscious planning, land use decisions, long range transportation plans, and, to proactively apply safety treatments in high risk TAZs.