浅论健美操教学方法

随着人民群众生活水平的不断提高,健美操运动越来越受到广大青少年的喜欢,现已成为各大中专院校的一项重要教学内容,通过多年的教学实践,对当前健美操教学中常用的教学方法进行全面综合、比较与分析,提出8种行之有效的教学方法,以期与各位同仁共同提高健美操教学质量,使健美操这一优秀的健身方法成为全民健身的重要形式和手段。     

计算流体力学(CFD)中的迭代法及其并行计算方法

应用计算流体力学 (CFD)方法分析事故原因已被广泛采用 ,笔者针对事故理论分析和流体计算过程中 ,运用CFD方法所存在计算量大的问题 ,分析和讨论了几种古典迭代法及其并行计算方法     

基于模糊颜色Petri网的表决DVP安全软件模型初探

把模糊计算理论和有色Petri网有机地结合起来 ,提出了一种模糊颜色Petri网诊断表决算法 ,把该算法应用于DVP的软件模型 ,使之具有故障容忍和表决的能力。笔者对以模糊颜色Petri网为核心的DVP软件模型表决算法进行了较为深入的探讨 ,该模型对提高软件系统的安全性和可靠性具有实际意义。     

ERODIBILITY OF URBAN BEDROCK AND ALLUVIAL CHANNELS,NORTH TEXAS1

ABSTRACT: Major erosion of urban stream channels is found in smaller basins in the North Texas study area with contributing drainage areas of less than ten square miles. Within these basins, four basic channel types are identified based on bed and bank lithologies: alluvial banks and bottoms, alluvial banks and gravel bottoms, alluvial banks with rock bottoms, and rock banks with rock bottoms. Most channels (75 percent) have alluvial banks with gravel or rock bottoms. Channel slopes are steep (.38 to.76 percent). Rock consists predominantly of shale and limestone. Channel cross sections are divided into the following four zones based on weathering, scour and entrainment mechanisms: soil zone, slake zone, rock zone and bed material zone. Erodibility of the channels is determined using multiple techniques including reach hydraulics and stream power computations, submerged jet testing, slab entrainment thresholds, and slake durability rates. Procedures are based on both empirical and modeled time series estimates of channel erosion. Field and modeled results support rates of erosion of up to four inches per year. Rates are tied to flow regime, climate, and type of channel bed and banks.     

An approach to integrate impact scoping with environmental impact assessment

Impact scoping is the process of identifying important issues of a proposal and focusing the environmental impact assessment (EIA) on the high-priority issues. Although impact scoping in one form or another has been inherent to EIA for some time, documentation of its development and discussion of refinements to impact scoping processes have not been forthcoming. This article traces the development of impact scoping through time and highlights the need for such processes in EIA. A focused environmental assessment (FEA) approach to impact scoping that is suitable for implementation in an EIA is presented here and advantages of its use are delineated. FEA is a three-staged process that encourages impact scoping through progressive steps including impact identification, assessment and management planning. FEA combines a suite of EIA methods including: issues matrices, impact hypotheses, valued ecosystem components, and stakeholder participation sessions to effectively integrate impact scoping with EIA.     

STABILITY AND REACH LENGTH IN WATER SURFACE PROFILE DETERMINATION1

ABSTRACT: Extension of basic step methods of backwater computation to reaches of finite length is examined. Accuracies of commonly accepted hydraulic loss equations under particular water surface profile conditions are compared. Simulation of energy lines within a reach by parabolic curves is found to minimize error provided orientation of the axis of the parabola is selected in accordance with prevailing hydraulic conditions. Theoretical basis for an index reach length beyond which single-step computation from end to end of the reach must be in error is developed. Reduction of this reach length by suitable factors tailored to hydraulic conditions yields a mathematically defined allowable reach length for backwater computation. When reach length does not exceed this allowable reach length, no significant error may be detected. Automatic insertion of synthetic cross sections interpolated between surveyed cross sections when these are inadvertently spaced too far apart enables computation to proceed. This device is error-free for prismatic channls but may introduce error for irregular natural channels. Preliminary trials indicate that results so obtained may be accepted provided the fall in the original reach does not exceed from one to two feet. When this is exceeded, additional cross sections should be surveyed.     

Size-Dependent Selective Leaf Damage by Insects and Some Methodological Implications of This Phenomenon

The area of leaves on birch (Betula pubescens ssp. tortuosa) auxiblasts and brachyblasts and the degree of their damage by the complex of leaf-gnawing and leaf-mining insects were studied in a light birch forest. The results showed that phyllophagous insects, primarily snout beetles, prefer young leaves on the apexes of auxiblasts. Thus, selective damage is inflicted on smaller leaves, both on the auxiblasts and in the entire sample. This phenomenon is widespread and may manifest itself in different ways, depending on the pattern of leaf area distribution along the extended shoot and the feeding preferences of the insects. Thus, it is necessary to reconsider research methods and approaches based on the assumption that insects damage leaves nonselectively, irrespective of their size.     

湖北省区域可持续发展能力综合评价

从区域可持续发展的观点出发，根据湖北省具体区域特征，通过构建湖北省区域可持续发展指标体系和评估方法，得出湖北省12个地市人口、资源、环境、经济和社会5个系统的可持续发展指数以及区域综合可持续发展指数。从总体上看，湖北省区域可持续发展水平处于偏低水平，其中武汉市是唯一具有强可持续发展能力的城市，但优势地位不明显；其它城市可持续发展5个系统均存在发展不平衡状况，且城市特色不突出。     

Suburbanization and drought: A mixed methods vulnerability assessment in rainy Massachusetts

This paper presents evidence that water restrictions in suburbanizing eastern Massachusetts towns are becoming more common, controlling for climate. We then assess the relationship between these suburban droughts and residential development. Focusing on the suburbs of Boston, seven towns independent of the Boston water supply system were selected to represent differing levels of sprawl-style growth. Water restrictions are becoming more frequent in all of the towns studied, and models demonstrate that restrictions are increasing in duration, independent of climate. Interviews suggest that residential development is playing a central role in this increasing sensitivity to suburban drought, though other factors are also important. Long-term planning and integration of land-use planning and water management emerged as two key paths for attenuating the impacts of development.