Alternative transportation fuel standards: Welfare effects and climate benefits

This paper develops an integrated model of the fuel and agricultural sectors to analyze the welfare and greenhouse gas emission (GHG) effects of the existing Renewable Fuel Standard (RFS), a Low Carbon Fuel Standard (LCFS) and a carbon price policy. The conceptual framework shows that these policies differ in the incentives they create for the consumption and mix of different types of biofuels and in their effects on food and fuel prices and GHG emissions. We also simulate the welfare and GHG effects of these three policies which are normalized to achieve the same level of US GHG emissions. By promoting greater production of food-crop based biofuels, the RFS is found to lead to a larger reduction in fossil fuel use but also a larger increase in food prices and a smaller reduction in global GHG emissions compared to the LCFS and carbon tax. All three policies increase US social welfare compared to a no-biofuel baseline scenario due to improved terms-of-trade, even when environmental benefits are excluded; global social welfare increases with a carbon tax but decreases with the RFS and LCFS due to the efficiency costs imposed by these policies, even after including the benefits of mitigating GHG emissions.     

风窗对井下通风系统的影响及其调节与定位优化

利用回路阻力平衡关系分析了井下风窗安装前后通风系统中各分支间风流流动关系,提出了某些分支安装风窗后,通风系统各分支的风量对此变化作出反应的分析模型,给出了度量风量和阻力反应敏感性强弱的方法;假定通风系统中某些分支同时安装风窗,在保留风窗的使用对通风系统所带来的正面作用,但要抑制其负面作用的条件下,基于尽可能使所有参与调节的分支的风阻增、减值最小化的原则,提出了指定分支实施调节的调阻调节法和优选分支实施调节的调阻调节法,并建立了相关最优调节模型及其求解方法。结果表明:两种模型可以在风窗安装之前进行解算,解算结果可预知风窗安装后通风系统各分支的风流的分布情况,并确定出相应的调控策略;优选分支调阻调节模型可以用于选择最优的风窗安装位置、数量及风窗阻力,后者可以用于确定风窗窗口面积。     

基于量子遗传算法的液压支架喷雾效率的参数优化设计

为了提高综采工作面液压支架喷雾的降尘效率,通过分析影响支架喷雾降尘效率的因素,以支架喷雾效率最高为优化目标,利用量子遗传算法对喷嘴到产尘点距离,雾化角度,喷雾压力,喷嘴个数,喷嘴直径多参数进行优化。结果表明:液压支架的采煤机移动喷雾降尘效率增加了1306%,液压支架上的移架/放煤喷雾降尘效率增加了1333%。此研究对于支架喷雾降尘系统的设计,参数的合理选取有一定的参考价值。     

用正交设计法研究阻燃LDPE薄膜配方

以低密度聚乙烯LDPE、氢氧化镁和微胶囊化红磷为原材料,利用正交设计法研究了新型阻燃薄膜配方,制备了阻燃型低密度聚乙烯薄膜,并对其氧指数进行测试.结果表明,新型配方中的氢氧化镁和微胶囊化红磷具有协同阻燃效果,并能在一定程度上解决燃烧时的熔滴现象;当氢氧化镁添加量小于29%时,两种阻燃剂对体系阻燃性的影响差别不明显;与纯LDPE薄膜相比,阻燃LDPE薄膜由于添加了上述两种阻燃成分,体系氧指数提高4%,改善了阻燃效果.     

面向生态城市建设的能源结构优化研究

基于信息熵分析了城市能源供应结构与能源消费结构的多样性,提出了生态城市能源结构优化的基础判据和约束判据.以厦门市为例,分析了城市能源结构自然演变趋势的缺陷,提出了实现生态城市建设的能源结构优化的控制方案,并判断其优化效果.结果表明,2020年前,基础情景下的厦门市能源供应结构多样性将减少,能源消费结构退化较显著,尤其是2015年前退化趋势加剧,且远远超过结构优化判据的约束条件.而通过采取提高能源生态效率,清洁燃料替代,新能源和可再生能源开发与利用,机动车用能调整强化等控制措施,2010年后厦门市未来能源结构总体上将明显优于系统自然演变结构,同时满足环境容量约束与倍数因子约束条件,从而为该市实现生态城市建设目标奠定基础.     

地震波非线性反演方法研究综述

地震波非线性反演方法研究跟正演模拟方法研究一样,是地球物理学中一个非常重要的研究领域,其进展对人们正确认识和了解地球内部的细节及物性具有重大意义,对地球动力学的研究也具有不可忽视的推动作用。对地震波非线性反演问题理论研究的进展作了评述;在简单回顾非线性反演方法发展历史的基础上,总结了近年来常见的非线性反演方法研究的最新进展情况,对非线性反演中存在的各种问题进行了比较和评述,同时指出了目前非线性反演方法存在的问题,并对今后发展的方向作了简要展望。     

Estimation of distribution algorithm enhanced particle swarm optimization for water distribution network optimization

The optimization of a water distribution network (WDN) is a highly nonlinear, multi-modal, and constrained combinatorial problem. Particle swarm optimization (PSO) has been shown to be a fast converging algorithm for WDN optimization. An improved estimation of distribution algorithm (EDA) using historic best positions to construct a sample space is hybridized with PSO both in sequential and in parallel to improve population diversity control and avoid premature convergence. Two water distribution network benchmark examples from the literature are adopted to evaluate the performance of the proposed hybrid algorithms. The experimental results indicate that the proposed algorithms achieved the literature record minimum (6.081 M$) for the small size Hanoi network. For the large size Balerma network, the parallel hybrid achieved a slightly lower minimum (1.921M€) than the current literature reported best minimum (1.923M€). The average number of evaluations needed to achieve the minimum is one order smaller than most existing algorithms. With a fixed, small number of evaluations, the sequential hybrid outperforms the parallel hybrid showing its capability for fast convergence. The fitness and diversity of the populations were tracked for the proposed algorithms. The track record suggests that constructing an EDA sample space with historic best positions can improve diversity control significantly. Parallel hybridization also helps to improve diversity control yet its effect is relatively less significant.     

工矿商贸行业较大以上次生衍生事故分析研究

通过对2012~2015年6月全国工矿商贸行业发生的较大以上次生衍生事故行业分布、地域分布、时段分布、空间分布等特征的分析,归纳总结了次生衍生事故发生的规律和特点,根据事故致因理论,对次生衍生事故原因进行了分析,并提出对策措施,为降低工矿商贸次生衍生事故发生率、减少人员伤亡提供理论支撑。     

Optimization of thermophilic anaerobic-aerobic treatment system for Palm Oil Mill Effluent (POME)

Optimization of an integrated anaerobic-aerobic bioreactor (IAAB) treatment system for the reduction of organic matter (Chemical Oxygen Demand (COD), Biochemical Oxygen Demand (BOD) and Total Suspended Solids (TSS) concentrations) in Palm Oil Mill Effluent (POME) to legal standards with high methane yield was performed for the first time under thermophilic condition (50°C–55°C) by using response surface methodology (RSM). The experiments were conducted based on a central composite rotatable design (CCRD) with three independent operating variables, organic loading rates in anaerobic compartment (OLR_an) and mixed liquor volatile suspended solids (MLVSS) concentration in anaerobic (MLVSS_an) and aerobic compartments (MLVSS_a). The optimum conditions for the POME treatment were determined as OLR_an of 15.6 g COD·L^-1·d^-1, MLVSS_an of 43100 mg·L^-1, and MLVSS_a of 18600 mg·L^-1, where high aerobic COD, BOD and TSS removal efficiencies of 96.3%, 97.9%, and 98.5% were achieved with treated BOD of 56 mg·L^-1 and TSS of 28 mg·L^-1 meeting the discharge standard. This optimization study successfully achieved a reduction of 42% in the BOD concentrations of the final treated effluent at a 48% higher OLR_an as compared to the previous works. Besides, thermophilic IAAB system scores better feasibility and higher effectiveness as compared to the optimized mesophilic system. This is due to its higher ability to handle high OLR with higher overall treatment efficiencies (more than 99.6%), methane yield (0.31 L CH₄·g^-1 COD_removed) and purity of methane (67.5%). Hence, these advantages ascertain the applicability of thermophilic IAAB in the POME treatment or even in other high-strength wastewaters treatment.     

An integrated model for structure optimization and technology screening of urban wastewater systems

The conventional approach to wastewater system design and planning considers each component separately and does not provide the optimum performance of the entire system. However, the growing concern for environmental protection, economic efficiency, and sustainability of urban wastewater systems requires an integrated modeling of subsystems and a synthetic evaluation of multiple objectives. In this study, a multi-objective optimization model of an integrated urban wastewater system was developed. The model encompasses subsystems, such as a sewer system, stormwater management, municipal wastewater treatment, and a wastewater reclamation system. The non-dominated sorting genetic algorithm (NSGA-II) was used to generate a range of system design possibilities to optimize conflicting environmental and economic objectives. Information from a knowledge base, which included rules for generating treatment trains as well as the performance characteristics of commonly used water pollution control measures, was utilized. The trade-off relationships between the objectives, total water pollution loads to the environment, and life cycle costs (which consist of investment as well as operation and maintenance costs), can be illustrated using Pareto charts. The developed model can be used to assist decision makers in the preliminary planning of system structure. A benchmark city was constructed to illustrate the methods of multi-objective controls, highlight cost-effective water pollution control measures, and identify the main pressures on urban water environment.