污水流量测量中流量计的选型与探讨

环保产业对污水流量的测量和控制的精确度、可靠性要求已越来越高 ,介绍了电磁式、涡街式、节流式等几种流量计的选型设计 ,结合水处理工艺 ,从理论和实践两方面阐述各自的特点     

EVALUATING DIRECT BENEFIT ESTIMATION PROCEDURES FOR IRRIGATION PROJECTS: A SIMPLIFIED APPROACH1

ABSTRACT: An integral part of evaluating the net benefits generated by an existing or proposed irrigation project is the assessment of the associated impacts in commodity markets. Traditionally, these impacts have been measured by either assuming no change in commodity prices and calculating net returns to project farmers, or by allowing commodity prices to fall in accordance with a given elasticity of demand and subtracting commodity production costs from the associated area under the commodity demand curve. In either case, it is implicitly assumed that supply is perfectly inelastic. This article establishes that traditional approaches to measuring direct benefits are biased. Formulae are presented for calculating the maximum absolute and relative error which may result from using these techniques as a function of project size. Direct benefit estimates are then evaluated for three irrigation projects in Nebraska, illustrating how these results can be used to improve project evaluation procedures.     

FLUME CONDITION ASSESSMENT IN COLORADO1

ABSTRACT: A study was conducted in which 66 Parshall flumes used for agricultural flow measurement were assessed for physical integrity, settlement, and submergence. A total of 292 physical defects was documented. A flow measurement error analysis was performed indicating that 52 percent of the flumes measured flow beyond ±3 percent of the correct value and 41 percent of the flumes measured flow beyond ±5 percent. The findings indicate that the infrastructure is aging. The flow measurement system comprised of flumes no longer provide an accurate accounting of water through the distribution network.     

Adsorption of Cotton Fabric Dyestuff Waste Water on Nigeria Agricultural Semi-Activated Carbon

The Kaduna river in Nigeria is in such great environmental stress that the self-purifying capacity of the river has been exceeded as a result of industrial discharges. The river water is blue-green and pollution build-up is evident on the river banks. Techniques were designed to rid the river of visible signs of pollution by incorporating the principles of adsorption and incineration.Semi-activated carbon from agricultural wastes were used to treat the waste water. Residual colors, amber, yellow and orange, were obtained and the solute removed ranged from 96-99.8% and the volatile residue removed by carbon treatment ranged from 3-3.8%. Incineration of 1 kg waste water yielded 40 g solid residue.Adsorption of dyestuff present in the waste water was linear and increased with concentrations of waste water per unit mass of guinea corn carbon. Replicate results yielded: y = 2.5 + 0.130x y = 2.306 + 0.017x where x =log10% concentration of dyestuff waste water (independent variable); y = log10 adsorption of dyestuff waste-weight gramme-1 carbon. Unit of weight = milligramme (dependent variable).For maize carbon, adsorption was linear but decreased with increasing concentrations. Replicate results were: y = 1.583 - 0.21x y = 0.52 - 0.32x x and y here are the same as above; with cane sugar carbon, adsorption was independent of concentrations. Student t-test showed no statistical difference between the replicates at the 99.5% level.     

夜间建筑施工噪声扰民测量时间探讨

通过对现有夜间建筑施工噪声测量方法关于测量时间及国家和深圳经济特区有关夜间施工规定的分析,阐述了夜间施工噪声扰民监测时间问题。     

The Strange Career of the Ringelmann Smoke Chart

The Ringelmann smoke chart was used in the United States to assess smoke emissions in the early twentieth century. In fact, it may have been the most important method for measuring air pollution between the late 1800s and the environmental era. However, the popularity of the Ringelmann chart stood in stark contrast to its lack of precision, which smoke abatement experts recognized and discussed among themselves. However, the critique of the Ringelmann scale rarely left the circle of experts and never jeopardized its use. This article discusses the reasons for this striking phenomenon, pointing out that the Ringelmann chart had strong practical and symbolic advantages: it allowed smoke abatement to be conducted in a public and transparent way. With that, the history of the Ringelmann smoke chart is an instructive model for the social construction of measuring techniques.     

PM1切割器性能测试系统的搭建与应用

为对PM_1切割器的性能进行准确评估,本文设计搭建了两套PM_1切割器性能测试系统.结果发现,多分散气溶胶测试系统发生的气溶胶稳定、均匀,符合对数正态分布;单分散气溶胶测试系统发生的气溶胶稳定,单分散性良好.采用上述两套系统对5种PM1旋风切割器进行了性能评价,结果表明,两套系统测试结果基本一致,5种旋风切割器的切割粒径D50均在(1.0±0.1)μm之间,sharp-cut和Stairmand两类结构设计的切割器几何标准偏差σg分别在1.2±0.1和1.4±0.1之间.     

Development of an on-line measurement system for water-soluble organic matter in PM2.5 and its application in China

Water-soluble organic matter(WSOM) represents a critical fraction of fine particles(PM_(2.5))in the air, but its changing behaviors and formation mechanisms are not well understood yet, partly due to the lack of fast techniques for the ambient measurements. In this study,a novel system for the on-line measurement of water-soluble components in PM_(2.5), the particle-into-liquid sampler(PILS)–Nebulizer–aerosol chemical speciation monitor(ACSM), was developed by combining a PILS, a nebulizer, and an ACSM. High time resolution concentrations of WSOM, sulfate, nitrate, ammonium, and chloride, as well as mass spectra, can be obtained with satisfied quality control results. The system was firstly applied in China for field measurement of WSOM. The mass spectrum of WSOM was found to resemble that of oxygenated organic aerosol, and WSOM agreed well with secondary inorganic ions. All evidence collected in the field campaign demonstrated that WSOM could be a good surrogate of secondary organic aerosol(SOA). The PILS–Nebulizer–ACSM system can thus be a useful tool for intensive study of WSOM and SOA in PM_(2.5).     

基于风险度量理论的煤矿安全的系统评价

对风险理论最新进展的评述认为 ,安全就是零风险 ,凡事总有风险 ,安全只是相对的 ;安全问题是系统风险问题 ,风险和安全是同一个系统不确定性状态的两种对称的描述 ;安全程度或风险大小不仅取决于客观自然因素也决定于主观因素。笔者根据姜青舫提出的满足风险度量公理的险度函数 ,对矿井风险体系的结构分析 ,提出了矿井风险集、矿井险度和安全度新型综合评价指标。使矿山的安全评价建立在合理风险理论的基础之上 ,其中相对险度指标可直接作为风险预警指标使用。     

从色觉、科学仪器、测不准原理看非决定论

通过对色觉、科学仪器、测不准原理的分析,认为认识在感性阶段是客主体相互作用的结果.感官的生物学意义在于对客体的区别.这种区别是相对准确的,而不是与客体严格一一对应的.科学仪器是人感官的延伸.色觉与其它感官和科学仪器同是人类认识工具.测不准问题是与认识工具直接相关,与客主体相互影响密不可分的,它在宏观上和微观上同时存在,它不是非决定论的理论依据.