A multivariable model for estimation of vapor cloud explosion occurrence possibility based on a Fuzzy logic approach for flammable materials

In this paper, a new method based on Fuzzy theory is presented to estimate the occurrence possibility of vapor cloud explosion (VCE) of flammable materials. This new method helps the analyst to overcome some uncertainties associated with estimating VCE possibility with the Event Tree (ET) technique. In this multi-variable model, the physical properties of the released material and the characteristics of the surrounding environment are used as the parameters specifying the occurrence possibility of intermediate events leading to a VCE. Factors such as area classification, degree of congestion of a plant and release rate are notably affecting the output results. Moreover, the proposed method benefits from experts' opinions in the estimation of the VCE possibility. A refrigeration cycle is used as the case study and the probability of VCE occurrence is determined for different scenarios. In this study, sensitivity analysis is performed on the model parameters to assess their effect on the final values of the VCE possibility. Furthermore, the results are compared with the results obtained using other existing models.     

Investigation on removal of p-nitrophenol using a hybridized photo-thermal activated persulfate process: Central composite design modeling

The aim of this work is the study of p-nitrophenol (PNP) removal, as a nitroaromatic compound, using a hybridized photo-thermally activated potassium persulfate (KPS) in a fully recycled batch reactor. Response surface method was used for modeling the process. Reaction temperature, KPS initial dosage and initial pH of the solution were selected as variables, besides PNP degradation efficiency was selected as the response. ANOVA analysis reveals that a second order polynomial model with F-value of 41.7, p-value of 0.0001 and regression coefficient of 0.95 is able to predict the response. Based on the model, the process optimum conditions were introduced as initial pH of 4.5, [KPS]₀ = 1452 mg/L and T = 66 °C. Also experiments showed that using thermolysis and photolysis of the persulfate simultaneously, the role of thermolysis is not considerable. A pseudo first order kinetic model was established to describe the degradation reaction. Operational cost, as a vital industrial criterion, was estimated so that the condition of initial pH of 4.5, [KPS]₀ = 1452 mg/L and T = 25 °C showed the highest cost effective case. Under the preferred mild condition, the process will reach to 84% and 89% of degradation and mineralization efficiencies, after 60 and 120 min, respectively.     

四川省宝兴县碳汇效应评估与碳减排

利用第三次森林清查(1984-1988年)中宝兴县数据,结合2005年TM遥感影像土地利用类型图土壤类型图,采用植被类型碳密度以及土壤碳密度经验值的方法,估算了宝兴县碳库以及自然生态系统碳汇。并收集宝兴能源消耗、土地利用变更、替代能源工程等人为因素的数据估算了宝兴县2005年的人为碳排放及碳减排放效应,从而计算出宝兴县总碳增汇效应,碳汇为452.80×106kg C,并分区定量、图形表示,为地方政府提供决策支持。     

河流污染物通量估算方法筛选及误差分析

准确估算污染物通量对河流污染物总量控制和水质保护具有重要意义,但常规监测方法通常不能进行连续采样,数据相对比较稀缺,因此,选择恰当的采样间隔和通量估算方法,并对方法可能带来的误差进行估算,对提高通量估算的可靠性具有十分重要的意义.基于此,以江西赣江滁槎水质自动站2005—2007年3个水文年的水量和水质资料为基础,采用Monte Carlo方法模拟时间间隔分别为2、3、5、6、10、15和30 d的河流水质离散采样方案,并计算每种采样方案下的通量.同时,采用偏差(系统误差)和不精确度(离散程度)两个指标,比较了A、B、C、D、E 5种常规通量计算方法的误差分布,并建立了各算法误差随时间间隔变化的相关性曲线,以对河流污染物通量估算方法进行筛选.研究表明,滁槎断面COD_Mn采用瞬时值C_i与时段平均流量 Q_p乘积的方法计算年通量更准确;而NH₄⁺-N由于瞬时通量与流量相关性不显著,采用时段瞬时通量平均计算年通量更准确.     

恭城—栗木断裂带的应变特征与变形环境探讨

通过系统的有限应变测量与差异应力估算,探讨了恭城—栗木断裂带的应变特征与变形环境,以其推动该断裂带的研究向更深层次发展。结果表明:①付林指数K的变化范围为0.32～1.67;应变主轴平均方位为276°∠21°,与断裂带的整体逆冲方向基本一致;断裂带的平均应变程度为2.26～3.00,属中等应变程度;断裂带的应变类型属压扁型应变与单剪型平面应变的一种复合叠加类型。②断裂带的差异应力值为40～80 MPa,变形深度小于10 km,属半脆性—半韧性的变形域。③断裂带的应变特征与变形环境及宏观构造样式基本吻合。     

土壤侵蚀经济损失分析及价值估算—以贵州省猫跳河流域为例

以贵州省猫跳河流域为例,运用环境经济学理论和方法,分析土壤侵蚀的经济损失内在机制,估算土壤侵蚀的经济损失,揭示土壤侵蚀经济损失分布的空间格局,为该区域水土流失防治提供科学依据。结果表明,研究区平均每年土壤侵蚀经济损失为36 602.44×104元,其中土壤养分损失占总损失的89.46%,土地废弃损失占总损失的4.64%,土壤水分损失占总损失的1.05%,泥沙损失占总损失的4.85%。旱地土壤侵蚀经济损失最大,占土壤侵蚀经济损失的61.94%。从各县来看,清镇市土壤侵蚀经济损失最大,占总经济损失的32.87%。研究区平均单位面积经济损失为1 174.86元/hm2,北部地区和西南部地区土壤侵蚀单位面积经济损失价值较大。推进水土流失治理,实行生态补偿制度势在必行。     

广州地区稻田甲烷排放通量研究

1993～1994年连续2a在广州东郊采用自动采样和气相色谱分析系统测量了稻田甲烷的排放率,首次获得了华南地区赤红壤类型稻田甲烷排放特征和排放通量?结果表明:广州地区稻田甲烷排放率的日变化和季节变化随气温?灌溉状态及水稻不同生长期而变化,早稻甲烷平均排放量为1.6mg/(m2·h);晚稻为1.25mg/(m2·h),排放率较国内其他观测点低?在当地常规干湿灌溉方式下,估算得到广东和广西两省稻田甲烷排放总量约为0.26Tg/a?      

油田生产设施环境安全距离理论与估算--以胜利油田东辛采油厂为例

油田生产设施环境安全距离为减轻或避免生产设施的潜在环境危害．解决城市发展和油田企业之间的利益冲突,以及事故后的人群紧急疏散提供了科学的决策依据。以胜利油田东辛采油厂为例．对井场类、站库类和管线类三类主要油气生产设施的环境安全距离进行了研究和估算。对于井场类设施．主要研究估算了井喷H2S泄漏的环境风险安全距离;对于站库类设施,主要研究估算了噪声环境影响安全距离;对于管线类设施,主要研究估算了泄漏事故环境风险安全距离。通过现场测量和模拟实验证明．估算结果比较可靠。     

Are rapid population estimates accurate? A field trial of two different assessment methods

Emergencies resulting in large-scale displacement often lead to populations resettling in areas where basic health services and sanitation are unavailable. To plan relief-related activities quickly, rapid population size estimates are needed. The currently recommended Quadrat method estimates total population by extrapolating the average population size living in square blocks of known area to the total site surface. An alternative approach, the T-Square, provides a population estimate based on analysis of the spatial distribution of housing units taken throughout a site. We field tested both methods and validated the results against a census in Esturro Bairro, Beira, Mozambique. Compared to the census (population: 9,479), the T-Square yielded a better population estimate (9,523) than the Quadrat method (7,681; 95% confidence interval: 6,160-9,201), but was more difficult for field survey teams to implement. Although applicable only to similar sites, several general conclusions can be drawn for emergency planning.     

Maximum likelihood fitting of the Poisson lognormal distribution

In this paper some properties and analytic expressions regarding the Poisson lognormal distribution such as moments, maximum likelihood function and related derivatives are discussed. The author provides a sharp approximation of the integrals related to the Poisson lognormal probabilities and analyzes the choice of the initial values in the fitting procedure. Based on these he describes a new procedure for carrying out the maximum likelihood fitting of the truncated Poisson lognormal distribution. The method and results are illustrated on real data. The computer program for calculations is freely available.