Critical Sampling Points Methodology: Case Studies of Geographically Diverse Watersheds

Only with a properly designed water quality monitoring network can data be collected that can lead to accurate information extraction. One of the main components of water quality monitoring network design is the allocation of sampling locations. For this purpose, a design methodology, called critical sampling points (CSP), has been developed for the determination of the critical sampling locations in small, rural watersheds with regard to total phosphorus (TP) load pollution. It considers hydrologic, topographic, soil, vegetative, and land use factors. The objective of the monitoring network design in this methodology is to identify the stream locations which receive the greatest TP loads from the upstream portions of a watershed. The CSP methodology has been translated into a model, called water quality monitoring station analysis (WQMSA), which integrates a geographic information system (GIS) for the handling of the spatial aspect of the data, a hydrologic/water quality simulation model for TP load estimation, and fuzzy logic for improved input data representation. In addition, the methodology was purposely designed to be useful in diverse rural watersheds, independent of geographic location. Three watershed case studies in Pennsylvania, Amazonian Ecuador, and central Chile were examined. Each case study offered a different degree of data availability. It was demonstrated that the developed methodology could be successfully used in all three case studies. The case studies suggest that the CSP methodology, in form of the WQMSA model, has potential in applications world-wide.     

Patchy Distribution Fields: Sampling Distance Unit of a Spiral Survey and Reconstruction Adequacy

A mathematical model is used to examine the effects of choosing various units of sampling distance of a spiral acoustic survey on the adequacy of reconstructing patchy distribution fields. The model simulates fish or plankton patches (or gaps) of different shapes and spatial orientations, and an acoustic survey by a spiral of Archimedes along which a unit of sampling distance is set. For comparison, surveys are imitated by parallel transects along which the same unit of sampling distance is set. Adequacy of the reconstructed fields to those originally generated is evaluated by calculating their correlations (r). In the case of a spiral survey, the mathematical experiments conducted show that an immovable field can be reconstructed properly (r ² > 0.70) if the ratio of the units of sampling distance to the autocorrelation radius for the field averaged in various directions d/R _av < 1.0–1.5. Regarding immovable fields, the spiral surveys ensure, practically speaking, the same adequacy of the field reconstruction as do surveys by parallel transects with the same unit of sampling distance. In regard to movable fields, a comparison of the results of spiral surveys with those of surveys by parallel transects indicates that the former may ensure even higher adequacy of the field reconstruction than do the latter, provided that the units of sampling distances in these surveys are equal to each other.     

Development of a landfill model to prioritize design and operating objectives

The application of scientifically based decision making tools to help address solid waste management issues dates back to the early 1960s. Researchers continue to use operations research tools to help optimize landfill design and operating parameters. This paper discusses the application of another type of decision making tool, the analytical hierarchy process (AHP), to address priority ranking for a number of landfill engineering design and operating objectives in developing and developed countries. In this application, the AHP is used to rank, and prioritize, economic, environmental, health and safety, legislative and public perception objectives for landfill design and operations specific to landfill distance from a community, and precipitation levels. Results from a global survey using the Delphi process are included, with a discussion on the survey’s impact on the objective rankings relative to community proximity and precipitation. The Delphi process worked extremely well, and was an excellent tool to use in this application. The initial results from the objective rankings show promise in the development of an integrated model for landfill design and operation.     

Patchy distribution fields: A spiral survey design and reconstruction adequacy

A mathematical model was used to examine the effects of a spiral survey design on the adequacy of reconstructing patchy distribution fields. The model simulates fish or plankton patches (or gaps) of different shapes and spatial orientations, and acoustic surveys by a spiral of Archimedes; for comparison, surveys by parallel or zigzag transects are imitated. Adequacy of the reconstructed fields to those originally generated was evaluated by calculating their correlations (r). The mathematical experiments conducted showed that spiral surveys ensure, practically speaking, the same adequacy of field reconstruction (both in cases of immovable or movable patches) as do surveys by parallel or zigzag transects with greater sampling effort (overall path). In the case of a spiral survey, a patchy field can be reconstructed properly (r² = 0.70) if the overall survey path is not less than S/R_av = 20–30, where R_av is the autocorrelation radius averaged for various directions. Thus, the results obtained allow us to conclude that a spiral survey design is expedient in cases that the minimal duration of a survey is a decisive factor for its conduction and there is a priori information that no onshore-offshore gradients of fish density exist in a region under study.     

Method for identifying errors in chemical process development and design base on accidents knowledge

It has been claimed that the high accident rate in the chemical process industry is due to poor dissemination of accident knowledge that affects directly the level of learning from accidents. In response to this situation, this paper utilized past accident knowledge as a basis to develop a safety oriented design tool whereby the accident information were directly disseminated into plant design. The method was developed based on our previous accident analysis of design error in which the common design errors were ranked in accordance to their frequency and its origins during normal plant design project. Based on the design error ranking and its origin at a specific design phases, a method for design error detection is proposed. The method is expected to be able to identify the possible design error and its causes throughout chemical process development and design. The main objective is to trigger safe design thinking at the specific design phases so that appropriate action for risk reduction could be timely implemented. The Bhopal and BP Texas tragedies are used as case studies to test and verify the method. The proposed method can detect up to 74% of design errors.     

Recycling of electronic displays: Analysis of pre-processing and potential ecodesign improvements

This article analyses the current and future end-of-life management of electronic displays (flat screen televisions and monitors), and identifies and discusses possible ecodesign recommendations to improve it. Based on an investigation of the treatment of displays in two typical European recycling plants, key aspects and criticalities of the recycling methods (sorting, dismantling and pre-processing) are identified. Disaggregated data concerning on-site measurements of the time needed to manually dismantle different displays are presented. The article also discusses the potential evolution of end-of-life scenarios for electronic displays and suggests possible recommendations for recyclers, producers and policy-makers to promote resource efficiency in the recycling of such waste products. Data on time for dismantling the displays can be used to build measurers for voluntary and mandatory policies, to stimulate design innovations for products improvement, and to assess possible alternative treatments of the waste during the pre-processing at the recycling plants. Some quantitative product measures (based on the time thresholds for dismantling some key components) are also discussed, including an assessment of their economic viability. These measures can potentially be enforced through mandatory and voluntary European product policies, and could also be extended to other product groups.     

管壳式循环水冷却器管束内漏的控制

管壳式换热器广泛应用于石油化工等装置,而管柬内漏的风险却一直困扰着装置的长周期运行。针对循环水冷却器管束内漏,结合制造与修理及相关文献的案例,从设计、制造及使用等控制环节对固定管板式、浮头式及u形管式等管柬的内漏进行了分析,为防止管束内漏的风险需要设计、制造及使用共同控制,并给出了合理的建议。     

汽车排放控制系统的设计策略探讨

简要介绍汽车排放污染物种类及其对人体的危害,阐述了现有汽车排放控制的技术措施,分析了汽车排放后处理技术存在的主要问题,提出汽车排放控制系统的设计方案,并对方案的可行性进行了分析研究.     

关于P-V因数在磨损可靠性设计中应用的思考

P -V因数是对摩擦副在边界润滑状态下工作 ,而规定的一个设计准则。由于磨损失效是XB型轴向柱塞泵的主要失效形式 ,所以 ,笔者提出 ,通过引用P -V因数的广义概念 ,建立起磨损可靠性基本设计的模型 ,并对XB -F4 0型轴向柱塞泵的滑履进行磨损可靠性设计。较成功地改善了摩擦副的磨损状况 ,提高了XB -F4 0型轴向柱塞泵的使用寿命 ,同时提供了一种可靠性设计的新思路。     

声学环境影响评价——大剧院设计声学案例分析

大剧院观众厅是音乐家最后的乐器,音乐效果是由观众厅声学反应出来的。前面演奏者要把声音传播给观众席,再从观众席后排反声回给演奏者,这样的互动是最完美的剧院设计。