Diffusion mechanism of lindane into wood charcoal

Abstract

The wood charcoal treated by 1N HNO₃ (WCT) was used to remove toxic chlorinated pesticide lindane (y‐HCH) residue from water by the sorption process. Using a simple first order reversible kinetics constants and half time equations, the film and pore diffusion coefficients were determined. Film diffusion was found to be rate limiting step in sorbing lindane by WCT. This was further authenticated by kinetics studies at different initial sorbate concentrations, different sorbent sizes, and different agitation speeds besides interruption test. A pore diffusion model was used to fit the data of kinetics in continuously mixed batch reactors (CMBR), and the tortuosity, external resistance, and surface diffusion effects on lindane sorption by WCT were noticed. The tortuosity values of 15 to 28 were obtained for WCT‐lindane system.     

Impacts of Upstream Building Width and Upwind Building Arrangements on Airflow and Pollutant Dispersion in a Street Canyon

A two-dimensional numerical model for evaluating the wind flow and pollutant dispersion within a street canyon was first developed using the FLUENT code, which was then validated against a wind tunnel experiment. Then, the effects of the upstream building width and upwind building arrangement on the airflow and pollutant dispersion inside an isolated street canyon were investigated numerically. The numerical results revealed that: (1) the in-canyon vortex center shifts downwards as the upstream building width increases; (2) the recirculation zone covers the entire upstream building roof for the cases when W/H = 0.5, 1.0, 1.5, and 2.0 (W is the upstream building width and H is the building height), whereas the flow reattaches the upstream building roof for the cases when W/H = 2.5 and 3.0; (3) when the upstream building width is shorter than the critical width W_C (= 2H), an increase in the upstream building width leads to an increase in the pollution level on the leeward wall of the canyon and a decrease in the roof-level concentrations at the upstream building; (4) when the upstream building width is longer than the critical width, the roof-level concentrations at the upstream building are negligibly small and the pollution level on the leeward wall of the canyon is almost unaffected by a further increase in the upstream building width; (5) when the buildings are placed upwind of the canyon, the flow attaches the upstream building roof and, therefore, almost none of the pollutants are distributed on the upstream building roof; and (6) the pollution levels inside the canyon and on the downstream building roof increase significantly with the number of upwind buildings.     

城市洪涝灾害的成灾模式初步分析

城市是一个通过水、电、气、交通、通讯、计算机网络等国民经济命脉系统联系在一起的集政治、经济、文化、外交等社会活动中心于一体的人口资产密集区。我国目前正处于经济和城市化高速发展时期,城市在发展的同时深刻地改变了当地自然环境,增加了洪涝灾害发生的频率,城市洪涝灾害损失也以前所未有的速度增长,城市洪涝灾害损失的基本模式,除了造成人员伤亡、建筑物和物资直接受损毁外,更在于命脉系统因灾瘫痪导致社会经济活动中断;地下设施迅速发展加重了洪涝灾害风险;建筑物内部财产损失比重增加;以及由洪涝灾害促使持续发展受阻和环境破坏等问题。     

烟气扩散的CFD数值模拟

运用商业CFD软件Fluent模拟计算小尺寸下的简单烟气扩散规律.将结果用正态分布假设下的高斯烟羽模型验证.证明该软件模拟烟气扩散问题的可行性.     

安徽嘉山台的多极距电阻率观测

利用1990年以来安徽嘉山台的多极距电阻率观测资料进行反演分析，结果显示： 嘉山台的浅层(第一层)电阻率变化幅度最大，认为是受气象和灌溉等因素的干扰； 第二层变化幅度迅速减小； 第三层变化平稳； 深层(第四层)电阻率变化幅度比二、 三层大，可能与层厚为∝有关，原因尚须进一步研究。     

南山铁矿风场及扩散规律风洞模拟研究

以风洞模拟方式研究中性层结条件下南山铁矿凹山采场地域边界层风场特征,并以示踪气体扩散摸拟方法给出该地域大气扩散参数的实验结果。     

Short-term wind speed forecasting based on random forest model combining ensemble empirical mode decomposition and improved harmony search algorithm

ABSTRACT

Wind speed forecasting plays an important role in power grid dispatching management. This article proposes a short-term wind speed forecasting method based on random forest model combining ensemble empirical modal decomposition and improved harmony search algorithm. First, the initial wind speed data set is decomposed into several ensemble empirical mode functions by EEMD, then feature extraction of each sub-modal IMF is performed using fast Fourier transform to solve the cycle of each sub-modal IMF. Next, combining the high-performance parameter optimization ability of the improved harmony search algorithm, two optimal parameters of random forest model, number of decision trees, and number of split features are determined. Finally, the random forest model is used to forecast the processing results of each submodal IMF. The proposed model is applied to the simulation analysis of historical wind data of Chaoyang District, Liaoning Province from April 27, 2015 to May 22, 2015. To illustrate the suitability and superiority of the EEMD-RF-IHS model, three types of models are used for comparison: single models including ANN, SVM, RF; EMD combination models including EMD-ANN, EMD-SVM, EMD-RF; EEMD combination models including EEMD-ANN, EEMD-SVM, EEMD-RF. The analysis results of evaluation indicators show that the proposed model can effectively forecast short-term wind data with high stability and precision, providing a reference for forecasting application in other industry fields.     

化工装置爆炸事故模式及预防研究

对建国以来我国已经发生的典型化工装置爆炸事故原因进行了统计分析 ,总结了爆炸危险性的影响因素。结合对已经发生的事故案例的剖析 ,提取并建立了装置内爆炸事故模式 ,对各种模式的爆炸机理和发生条件进行了初步的研究分析 ,并提出事故的预防措施 ,以期指导安全生产     

西南岩溶石山地区岩溶水资源合理开发利用模式

针对湘西洛塔岩溶区特殊的地质环境所造成的干旱缺水、水土流失、生态环境恶化等问题的特点，在调查、分析洛塔自然条件与水土资源、生态环境基本条件的基础上，实施了13处岩溶水资源开发利用示范工程。通过系统总结洛塔地区岩溶水资源合理开发利用技术与方法及岩溶水资源开发利用成功经验，提出了以岩溶水小流域为单元对岩溶水资源进行综合开发利用的5种模式：①地下河堵洞引水开发利用模式；②地下河出口及岩溶大泉引水开发利用模式；③凿引水隧洞拦截地下河开发利用模式；④地表地下联合水库开发利用模式；⑤表层岩溶泉开发利用模式。通过对失败工程的案例分析，认为在岩溶水资源开发利用过程中，应查清工程的岩溶发育规律及工程地质条件，分析经济技术支持的可行性，然后采取相适应的开采方式与方法。岩溶水资源进行综合开发利用的5种模式的提出，为在湘西实施“水源〖DK1〗·土地〖DK1〗·生态”持续发展战略，发展生态经济，实现脱贫致富，促进社会经济、生态环境良性循环，提供了切实可行的实用技术与方法借鉴。     

基于FTA-SVM的车辆发动机故障识别方法

发动机结构日益复杂,其故障具有多样性和频发性的特点,收集大量故障样本存在很多实施障碍。为了提高车辆发动机的故障识别的效率和准确性,提出了一种新的结合故障树(FTA)和支持向量机(SVM)各自特点,从故障模式分析到故障类型识别的FTA-SVM故障识别方法。首先利用故障树在复杂系统故障模式分析中的优势,找出系统的故障模式,建立故障树模型,通过对故障树模型中各故障事件的分析,采集与故障事件状态相关的数据,建立数据与故障树底事件的映射模型,最后利用支持向量机在小样本数据处理中的优势,进行故障类型的识别。以发动机的失火故障为例建立了发动机失火故障树模型及故障数据与故障模式映射模型,验证了FTA-SVM方法的有效性和适用性。