多层采空区流场局部动态平衡数学建模分析

针对大同矿区浅埋深、多煤层群、近距离、两硬条件下开采形成的多层采空区极易发生自燃的问题,进行风流流场调压分析,以达到控制采空区遗煤自燃及防止有害气体流人工作面的目标.建立了多层采空区流场调压数学模型,得出工作面风压调节的最优参数,结合工程实际分析,确定了多层采空区流场调压需要达到的预期效果.提出多层采空区流场局部动态平衡的调压方法,结合达西线性渗流定律,确定了多层采空区流场达到局部动态平衡的调压允许范围,并提出调压自动控制方法.     

碳酸盐-硫酸盐矿物强化垃圾渗滤液厌氧处理研究

厌氧消化通常是垃圾渗滤液生物处理的首要环节,但处理效率不高.本研究尝试通过添加碳酸盐、硫酸盐等矿物来提高垃圾渗滤液的厌氧转化效率.研究共设置5组厌氧生物反应器,包括投加硬石膏、方解石、石膏、白云石的反应器及空白对照,考察添加矿物对垃圾渗滤液厌氧消化的影响.从实验结果可以看出,添加矿物的反应器中COD的去除率可以达到75%左右,而空白对照组去除率尚不足60%,添加矿物反应器甲烷产量显著高于对照.从反应器中的p H变化可以看出,矿物的添加可以提高溶液中的p H.研究结果表明,添加碳酸盐/硫酸盐矿物对垃圾渗滤液中的有机物厌氧消化过程具有重要的促进作用.     

湖北四湖流域的洪涝灾害与景观生态建设

对湖北四湖流域洪涝灾害的灾变趋势进行了分析，讨论了流域的景观生态特征及其对洪涝灾害的影响，提出了若干景观生态建设的对策。     

第一届亚太区安全健康海报、录像带创作比赛即将在港举行我国有关职业安全卫生单位积极报名参赛

第一届亚太区安全健成海报、录像带创作比赛即将在港举行我国有关职业安全卫生单位积极报名参赛第十三届亚太区职业安全健康组织大会及展览会将于１９９７年４月２１日至４月２６日在香港举行，这是香港职业安全健康局首次主办的大型国际性会议，预计将有二千多人参加，此...     

Determination of the carbon content of biomass—A prerequisite to estimate the complete biodegradation of polymers

This article presents a method to determine the carbon content of biomass, which is formed when degrading biodegradable polymers in an aerobic aqueous test system. Existing methods for determining the carbon content of biomass (e.g., fumigazation, protein assays, dry solids) have several disadvantages when applied for polymer degradation tests. In this work a protein assay based on the Lowry method was used. It was shown that the ratio between protein and carbon content is not constant but depends on the composition of the microbial population, the growth phase, and the substrate supply. This effect was used for the method presented in this article. For determining the carbon content of biomass the absorbance obtained by the Lowry test is correlated directly with the carbon content of biomass in dependence on the duration of the degradation test. The calibration curves are obtained by a mixed population of microorganisms during the course of a degradation test.     

我国西南湖塘溪流的水化学组成与离子平衡的研究

本文研究了我国重酸雨地区四川，贵州省湖塘溪流的水化学组成及离子平衡关系，结果表明：城郊之间水化学组成存在差异；同时，进行离子平衡衡算时，须对溶解态钙，镁进行校正，否则，会出现阴离子短缺现象，仅由钙，镁及硫酸根和弱酸根组成的简单离子平衡也是大致符合的，但其应用有一定的局限性。     

关于建立我国资源节约型经济体系的认识

从可持续发展角度看,我国资源节约型经济体系机制应在坚持集约经济和适应消费的基础上,强调社会生产与消费两者间的平衡和协调发展,欲达此目的,加快市场经济体系的完善和国家宏观指导是保障这一体系机制正常运转的根本条件。     

MASS BALANCE MODEL ESTIMATION OF PHOSPHORUS CONCENTRATIONS IN RESERVOIRS1

ABSTRACT: Mass balance models have been common tools in lake quality management for some years. However, verification for use on reservoirs, especially in the Western United States, has been seriously lacking, In this study, such a verification is attempted using data from the U.S EPA National Eutrophication Survey. Several models from the literature are compared for accuracy in application to the western reservoir data. Model standard error and correlation between estimated and observed reservoir phosphorus concentrations are the Criteria used for comparison. Standard errors am further used to calculate uncertainty of trophic state classification based on estimated phosphorus concentration. The model proposed by Dillon and Rigler (1974) proved most accurate, with a correlation coefficient of 0.86 and standard error of 0.2, based on logarithmic transformed values. Deficiencies in the other models appear to & from coefficients fit to lake data and from inappropriate model formulation.     

SEEPAGE FLOW INTO FLORIDA LAKES1

ABSTRACT: Direct measurements indicate that subsurface seepage in the littoral zone contributed 17.5 and 2.0 percent of the total hydraulic inputs, respectively, to Lakes Conway and Apopka, Florida. Two variations of seepage measuring devices were evaluated and gave relative standard deviations of 7 and 24 percent. Measurement inaccuracies were minimized by using large diameter (0.9 cm ID) plastic tubing. For a given transect perpendicular to shore, flow patterns were reproducible over time. Seepage flows ranged from 0 to 112 1/m²-day and most were between 4 and 30 1/m²-day. The detection limit was about 0.2 1/m²-day for a one-hour collection period. Seepage occured primarily within 30 m of shore and generally decreased exponentially with distance from shore. The shape of the bottom profile influenced flow patterns; lake bottoms with steeper slopes had higher flows that were compressed within a narrower zone. After a short-term rain event at Lake Conway, seepage flows increased rapidly to 2.4 times the prerain flow for 1 h and decreased to near background within about 6 h.     

PREDICTION OF STREAM TEMPERATURE IN FORESTED WATERSHEDS1

ABSTRACT: Removal of streamside vegetation changes the energy balance of a stream, and hence its temperature. A common approach to mitigating the effects of logging on stream temperature is to require establishment of buffer zones along stream corridors. A simple energy balance model is described for prediction of stream temperature in forested headwater watersheds that allows evaluation of the performance of such measures. The model is designed for application to “worst case” or maximum annual stream temperature, under low flow conditions with maximum annual solar radiation and air temperature. Low flows are estimated via a regional regression equation with independent variables readily accessible from GIS databases. Testing of the energy balance model was performed using field data for mostly forested basins on both the west and east slopes of the Cascade Mountains, and was then evaluated using the regional equations for low flow and observed maximum reach temperatures in three different east slope Cascades catchments. A series of sensitivity analyses showed that increasing the buffer width beyond 30 meters did not significantly decrease stream temperatures, and that other vegetation parameters such as leaf area index, average tree height, and to a lesser extent streamside vegetation buffer width, more strongly affected maximum stream temperatures.