共查询到20条相似文献，搜索用时 31 毫秒
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The previously described computer based system, Best Available Technology Evaluator (BATE), is used for least cost comparison of AST and AST with GPGAC and LPGAC processes. The underlying LPGAC cost and process dynamics simulation models are complex and need to be modified and coupled in an efficient manner in order to yield useful preliminary design data. This paper discusses a technique for such model combination and a method for finding the LPGAC least cost. Sensitivity analysis of LPGAC cost and performance with respect to common operating parameters such as empty bed contact time (EBCT), hydraulic loading rate (HL), and process configuration is discussed in light of this efficient model combination and least cost finding technique. This study shows that there is an optimal combination of EBCT and LPGAC process configuration for which its cost is comparable to that of AST alone and AST with GPGAC. Such optimal combinations are discussed for some VOC scenarios. 相似文献
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J. C. Agunwamba 《Water, air, and soil pollution》1991,59(3-4):299-309
A graphical method was applied to cost minimization in the waste stabilization pond subject to area, depth and efficiency constraints. The solution have the values of area, cost and depth at optimality. The paper also compared the optimal solutions for both plug-flow and completely-mixed flow models. Although the optimal depths for the design data considered was the same for the two models, the plug-flow model cost only one-fifth of that of completely-mixed flow model. The area occupied by the latter was found to be four times larger. 相似文献
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The present paper describes a rational approach to minimum cost design of an integrated activated sludge process which includes activated sludge reactor, secondary clarifier and sludge recycle. The cost of anaerobic digestion of excess sludge produced is also considered. Procedures for optimal design of both single and multiple stage activated sludge processes, considering construction and operational costs are developed. Biomass concentration in aeration tank and return sludge are utilized as the primary independent design variables to which system performance is related for single stage process. In the multiple stage process, additional design variables (flow and volume fractions for each stage) are included in design vector. Liquid-biomass separation is based on the batch solids flux theory. The optimization problem is framed as minimization of capital and operating cost subject to the constraints determined by effluent quality criteria and process variables affecting the performance. The interior penalty function method is used. Results definitely favor the application of multiple stage process over single stage. The major factor which appears to be contributing to reduction in cost is the biological solids retention time and hence the aeration tank volume. 相似文献
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土壤优化采样策略研究进展 总被引：6，自引：0，他引：6
[目的]对现有的采样方式进行系统地总结归纳,并探寻一种优化的采样策略,对采样强度、分析成本及其研究精度三方面进行均衡,即以最小的经济投入换取最大化的试验精度。[方法]广泛查阅近几年国内外的相关文献,对土壤优化采样策略的设定进行了系统的总结。将优化采样策略的理论分为合理采样数和样点布设两方面,就此分别介绍确定采样数的3种方法和确定样点布设的4种方式,详细介绍其发展现状,并对该领域今后的研究进行展望。[结果]目前的优化采样法大多基于模型来优化采样设计的研究,其初步采样的方式忽略了空间相关性所导致的信息损失,必然在一定程度上造成试验结果的偏差和人力物力的浪费。而且,研究尺度多集中在县级以下,没有对采样方案的设计确立统一的评价体系和标准。[结论]未来优化采样设计在样点优先级方面还应进行更加深入的研究。 相似文献
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Selecting a survey design to detect change through time in an ecological resource requires balancing the speed with which a given level of change can be detected against the cost of monitoring. Planning studies allow one to assess these tradeoffs and identify the optimal design choices for a specific scenario of change. However, such studies seldom are conducted. Even worse, they seem least likely to be undertaken when they offer the most insight – when survey methods and monitoring designs are complex and not well captured by simple statistical models. This may be due to limited technical capacity within management agencies. Without such planning, managers risk a potentially severe waste of monitoring resources on ineffective and inefficient monitoring, and institutions will remain ignorant of the true costs of information and the potential efficiency gains afforded by a moderate increase in technical capacity. We discuss the importance of planning studies, outline their main components, and illustrate the process through an investigation of competing designs for monitoring for declining brown bear (Ursus arctos) densities in southwestern Alaska. The results provide guidance on how long monitoring must be sustained before any change is likely to be detected (under a scenario of rather strong true decline), the optimal designs for detecting a change, and a tradeoff where accepting a delay of 2 years in detecting the change could reduce the monitoring cost by almost 50%. This report emphasizes the importance of planning studies for guiding monitoring decisions. 相似文献
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为探究配置方式对喷灌机组整体性能的影响,明晰不同配置方式的特点,在前期调研的基础上,以轻小型灌溉机组4.4CP-45为例,分别以单位面积上资源消耗,如机组能耗、年费用及使用年限内总费用等为评价指标,结合实际使用配置方式,采用遗传算法,讨论平坡条件下配置不同喷头10PXH、15PY、20PY及40PY时的喷头数及管径等最优组合方式,并对每种配置方式的适用范围进行分析。研究结果表明,通过3个优化目标下机组最优配置方式的对比,较好地反映出每种配置方式的优劣,与实际使用方式吻合较好。配置40PY 喷头时,机组单位能耗高,但年费用很低,适于抗旱或大田作物的灌溉;配置15PY 喷头时,优化配置下的机组能耗比初始配置时降低7.3%,比配置20PY降低8.3%,同时各项费用都比较低,灌溉均匀性高,但移动时劳动强度较大,适于经济作物或植物幼苗的灌溉;配置20PY喷头时,机组总费用最低,为6284.8元/hm2,比初始配置降低15.4%。所有配置方式下能耗费、运行费分别占据机组年费用及总费用的主要部分,有必要通过配置优化或采用中低压喷头、改善管理以降低系统能耗。该研究可以为机组的合理设计、喷头选择及应用推广提供参考。 相似文献
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大型泵站系统运行优化模型与节能效果比较 总被引：4，自引：4，他引：0
为了解大型泵站系统运行优化节能效果,分析了大型泵站优化运行方案的研究优化范围。以泵装置效率最高为优化目标,建立了单台机组变角运行优化模型和变速运行优化模型;在抽水流量和装置扬程一定的情况下,以运行费用最低为优化目标,建立了单座泵站、并联泵站运行优化模型;在抽水体积一定的情况下,考虑扬程变化和分时电价,以运行费用最低为优化目标,建立了单座泵站、并联泵站、并联泵站系统和梯级泵站系统的运行优化模型。3个应用实例考虑的优化范围与影响因素不同,优化计算结果表明,单台机组最优叶片角度下泵装置效率较设计角度最高可提高4.21个百分点;实行分时电价、变角调节的单座泵站系统运行优化方案和梯级泵站系统运行优化方案分别较设计方案节约电费5.64%和6.83%。提出了大型泵站系统运行优化建模时应综合考虑输变电、泵站和河道输水三方面能量损失。优化范围与考虑的因素越全面,节能与节约电费效果越显著。 相似文献
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Stephen E. Wright Belle M. Sigal A. John Bailer 《Journal of Agricultural, Biological & Environmental Statistics》2010,15(4):491-509
An optimal experimental design combines high-quality parameter estimation with efficient use of resources. This paper proposes
a new method for heuristic optimization of experimental designs in the presence of variable sampling costs. The method finds
the inexpensive designs with desirable statistical qualities and provides substantial insight regarding the relative importance
(in monetary terms) of sampling at specific design points. The method is illustrated within the context of a start-stop exposure
study in aquatic toxicology. Fast heuristics enable the analyses of a large range of sensitivity issues and examination of
trade-offs between information and cost. The method is described for designs in which replicate sampling is prohibited; a
generalization allowing for replicate sampling is provided as an appendix in the online supplemental materials. 相似文献
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耕地变化空间抽样调查方案的精度与效率分析 总被引：7，自引：4，他引：3
已有研究表明,利用遥感空间抽样方法来监测耕地变化是可行的,如何选择最佳空间抽样方案以提高效率、节省费用则是其需解决的核心问题。采用3种抽样方法（简单随机抽样、分层抽样、系统抽样）与2种抽样框（规则抽样框、不规则抽样框）,设计了6种不同组合的遥感空间抽样方案进行试验;根据不同抽样框与平均每样本调查费用大小的关系,分析了不同耕地变化遥感空间抽样调查方案的精度与效率,并以北京市顺义区为例进行了试验验证,结果表明：采用分层-不规则框进行耕地变化遥感空间抽样调查具有较高的精度和效率。进一步的敏感性分析表明,分层-不 相似文献
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Optimal interpolation and isarithmic mapping of soil properties 总被引：3，自引：1，他引：3
The principle of optimal estimation using regionalized variable theory is extended from that of a single soil property to situations where there are two or more spatially interdependent ones. Auto and cross semi-variograms express the spatial relations among the properties concerned. They can be estimated from data and can then be used to interpolate the values of a variable by co-kriging from measurements of it plus data on one or more other properties that have been more intensively sampled. The technique of co-kriging is described and illustrated by a case study of the particle size distribution at Woburn experimental farm. There was a strong co-regionalization with common anisotropy between topsoil silt, subsoil silt and subsoil sand. This allowed topsoil silt to be estimated and mapped by co-kriging more precisely than by kriging from data on topsoil silt alone. When the auto and cross semi-variograms for a set of variables are known in advance or estimated from reconnaissance they can be used to plan an optimal sampling scheme. The main variable is sampled on a rectangular grid with finer grids for subsidiary variables. The maximum kriging variances are calculated for a range of sample spacings and relative sampling intensities. Those that match the maximum tolerable variance are potentially useful. The optimum scheme is the one that achieves the desired precision for least cost. For Woburn it is shown that measuring a main variable would need to cost at least 5 times that of a subsidiary variable to make a design for co-kriging economically sound. Such differences are unlikely for particle size fractions. Nevertheless there are many other instances in soil research where there are large differences in cost. If there is also a strong co-regionalization then savings should be possible by designing a sampling scheme that takes advantage of co-kriging. 相似文献
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人工明渠是中国北方灌区采用的主要输水方式。合理的渠道断面参数计算是水利计算中的重要环节。因此,合理的模型与较高精度的计算方法是求解渠道断面的关键。然而传统灌区混凝土衬砌渠道断面优化设计仅从最优水力断面角度出发,考虑单一水力要素,而忽视了渠道冻胀安全以及工程造价的问题。该文建立了以最优水力断面、工程造价最小为目标,满足混凝土衬砌渠道冻胀要求的数学模型。根据模型非线性的特点,利用自适应粒子群优化算法,对混凝土衬砌渠道梯形断面结构进行优化,选用自适应粒子群算法可以很好地克服算法陷入局部最优解的问题。建立的模型将混凝土衬砌量与工程占地最小作为目标函数优化。优化结果在最佳水力断面基础上,满足边坡稳定与工程量最小。最后将模型应用于黑龙江依兰县倭肯河灌区学兴干渠,分析了渠道边坡系数、渠底宽和渠道水深对目标函数的影响规律。优化结果表明,模型计算所得渠道工程占地减小1.5%,混凝土衬砌量减小1.8%。各个参数中,边坡系数对目标函数影响较大。混凝土衬砌厚度由土壤性质、冻结力大小所决定。该研究成果为提高寒区混凝土防渗渠道优化设计水平及灌区运行效益提供了理论依据。 相似文献
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Atte Moilanen 《Biological conservation》2005,124(4):485-492
Spatial reserve design concerns the planning of biological reserves for conservation. Typical reserve selection formulations operate on a large set of landscape elements, which could be grid cells or irregular sites, and selection algorithms aim to select the set of sites that achieves biodiversity target levels with minimum cost. This study presents a completely different optimization approach to reserve design. The reserve selection problem can be considerably simplified given the reasonable assumptions that: (i) maximum reserve cost is known; (ii) the approximate number of new reserves to be established is known; (iii) individual reserves need to be spatially contiguous. Further assuming the ability to construct a set of reserves in an efficient and close to optimal manner around designated reserve locations, the reserve selection problem can be turned into a search for a single interior point and area for each reserve. The utility of the proposed method is demonstrated for a data set of seven indicator species living in an conservation priority area in Southern Australia consisting of ca 73,000 selection units, with up to 10,000 cells chosen for inclusion in a reserve network. Requirements (ii) and (iii) above make interior point search computationally very efficient, allowing use with landscapes in the order of millions of elements. The method could also be used with non-linear species distribution models. 相似文献
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Obiora Cornelius Collins 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2018,68(5):412-423
Maize is a very important food crop world-wide and is vulnerable to diseases. Maize varieties that have high disease resistance are highly recommended for economic and health reasons. We consider a maize field with multiply varieties and develop a mathematical model to investigate the impact of foliar disease on the population dynamics. The possible benefit of considering control measures in reducing the spread of foliar diseases are evaluated. Results show that farmers must be aware of the disease dynamics of each variety as the dynamics vary. Also, in controlling diseases some methods are more effective than others. For the example given here controlling susceptibility of seeds to disease was the most effective method. As controlling diseases can be costly, optimal methods are important. Our results show that the most effective controls are those introduced at the outset of an outbreak and this can reduce the spread of diseases with the least cost. 相似文献
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对于大体积混凝土最优温控方案的选取,传统方法是按照规范的要求和人工反复修改方案,存在效率低下和受限于经验的问题。该文采用改进的微粒群算法(PSO,particle swarm optimization)优化方法,以及基于有限元(FEM,finite element method)的混凝土温度场和应力场仿真算法联合进行优化。算例设定了2个优化目标,即只考虑安全性的单目标优化(多特征点达到最小防裂安全系数1.8),以及考虑安全性和经济性的双目标优化(温控综合成本最小化)。计算结果表明,所提方法能够实现温控方案的自动寻优,优化结果更科学合理,总体研究效率可提高50%以上。考虑双目标优化后,在确保防裂安全的条件下能够明显降低温控措施的综合成本。 相似文献
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Susan M. Parker Chris Gennings 《Journal of Agricultural, Biological & Environmental Statistics》2008,13(3):334-354
Classical optimal design theory may produce experimental designs that are biologically or characteristically inappropriate.
Often, there is a particular study goal along with many practical experimental concerns that a researcher may wish to include
in the optimal design process. This article provides a technique that allows a researcher to incorporate desired experimental
characteristics into an adjusted optimal design criterion. This technique uses a weighted overall desirability function to
penalize the optimal design criterion. A researcher may define an overall desirability function using any number of individual
desirability functions to influence the properties of an optimal experimental design. The methodology is illustrated with
two dose-response examples. 相似文献