Department of Civil and Environmental Engineering, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia.
Environ Monit Assess. 2013 May;185(5):3917-29. doi: 10.1007/s10661-012-2840-5. Epub 2012 Sep 2.
The evaluation of the status of a municipal drinking water treatment plant (WTP) is important. The evaluation depends on several factors, including, human health risks from disinfection by-products (R), disinfection performance (D), and cost (C) of water production and distribution. The Dempster-Shafer theory (DST) of evidence can combine the individual status with respect to R, D, and C to generate a new indicator, from which the overall status of a WTP can be evaluated. In the DST, the ranges of different factors affecting the overall status are divided into several segments. The basic probability assignments (BPA) for each segment of these factors are provided by multiple experts, which are then combined to obtain the overall status. In assigning the BPA, the experts use their individual judgments, which can impart subjective biases in the overall evaluation. In this research, an approach has been introduced to avoid the assignment of subjective BPA. The factors contributing to the overall status were characterized using the probability density functions (PDF). The cumulative probabilities for different segments of these factors were determined from the cumulative density function, which were then assigned as the BPA for these factors. A case study is presented to demonstrate the application of PDF in DST to evaluate a WTP, leading to the selection of the required level of upgradation for the WTP.
评估市政饮用水处理厂（WTP）的状况很重要。评估取决于多个因素，包括消毒副产物（R）对人体健康的风险、消毒性能（D）以及制水和配水的成本（C）。证据的 Dempster-Shafer 理论（DST）可以将 R、D 和 C 的各个状况结合起来，生成一个新的指标，从而评估 WTP 的整体状况。在 DST 中，影响整体状况的各个因素的范围分为若干个区间。这些因素的每个区间的基本概率赋值（BPA）由多位专家提供，然后进行组合以获得整体状况。在进行 BPA 赋值时，专家会使用他们的个人判断，这可能会在整体评估中引入主观偏见。在这项研究中，引入了一种避免主观 BPA 赋值的方法。使用概率密度函数（PDF）来描述对整体状况有影响的因素。从累积密度函数中确定了这些因素的不同区间的累积概率，然后将其作为这些因素的 BPA 进行赋值。本文提出了一个案例研究，演示了 PDF 在 DST 中用于评估 WTP 的应用，从而选择了 WTP 所需的升级水平。
