Accuracy and optimal sampling in Monte Carlo solution of population balance equations

Implementation of a Monte Carlo simulation for the solution of population balance equations (PBEs) requires choice of initial sample number (N₀), number of replicates (M), and number of bins for probability distribution reconstruction (n). It is found that Squared Hellinger Distance, H², is a useful measurement of the accuracy of Monte Carlo (MC) simulation, and can be related directly to N₀, M, and n. Asymptotic approximations of H² are deduced and tested for both one‐dimensional (1‐D) and 2‐D PBEs with coalescence. The central processing unit (CPU) cost, C, is found in a power‐law relationship, , with the CPU cost index, b, indicating the weighting of N₀ in the total CPU cost. n must be chosen to balance accuracy and resolution. For fixed n, M × N₀ determines the accuracy of MC prediction; if b > 1, then the optimal solution strategy uses multiple replications and small sample size. Conversely, if 0 < b < 1, one replicate and a large initial sample size is preferred. © 2015 American Institute of Chemical Engineers AIChE J, 61: 2394–2402, 2015     

基于混沌粒子群算法的多目标调度优化研究

针对当前车间调度多目标优化研究存在收敛速度慢、精度低的问题,提出了混沌多目标粒子群优化算法。在算法中,设计了一种新的叠加Logistic扰动的Tent混沌映射算子,通过该算子周期性地更新种群以保证种群的多样性;对收缩粒子群算法进行了扩展使其能够快速收敛到Pareto前沿。通过标准测试问题与实际应用对所提方法进行了验证,实验结果显示混沌多目标粒子群优化算法无论在收敛速度还是在优化精度上都优于其它典型多目标进化算法。     

Dynamic behavior of a distributed incinerator power system under output power variation

In Taiwan, the sales revenues of power generation from incinerator power plants with heat recovery power generation sold to the power company were up to NT$4.5bn, making the incinerator power generation play an important role in reduction of impact on environment and substitution of energy in power generation. Studying the dynamic behavior of incinerator power systems under output power variation is thus an essential task for the scheduling, operation, and expansion of incinerator power plants, such as, for cooperating with a scheduling program based on pricing signals to capture energy trading timing economically and to operate the incinerator power system securely. Although there are many studies on incinerator power generation, they seldom discuss the power generation system characteristics. In this paper, mathematical dynamic models for a distributed incinerator power system were derived and implemented using Matlab/Simulink, and dynamic characteristics of the system were further simulated and discussed under two operating modes: increment and decrement of power generation. These developed models can provide dynamic characteristics for these two modes, serving as an important analytic tool for cooperating with a scheduling program based on pricing signals to capture energy trading timing economically and to operate the incinerator power system securely. Copyright © 2014 John Wiley & Sons, Ltd.     

Evolution of the Metaponto District,Southern Italy: From Land Reform to New Sustainable Scenarios

In this paper we have represented the economic, environmental and territorial transformation of Metaponto district (southern Italy) generated by the land reform since 1950. The coastal area, once inhospitable and unproductive, through land reform has become a point of development for the entire Basilicata Region. The intensive model of economic development applied to agriculture and tourism today represents the main critical points of high environmental impact. In particular, the great human pressure exerted by economic activities has led to an insufficient capacity of water purification systems in the area and such criticism is amplified in the summer mainly for seaside tourism. In this study we have measured the environmental load exerted on the territory and we have estimated the human pressure on the district in the year 2030 and made proposals for amendments to current patterns of development in the agricultural and tourist sectors.     

Polluting facilities and environmental justice – a study

The environmental justice movement attempts to examine the disproportionate exposure of environmental pollution on minority and low‐income people, understand the patterns of such disproportionate exposures and develop strategies to reduce and eliminate such exposures. Unlike several environmental justice studies that include all fifty states of the United States, this study examines the locations of manufacturing facilities that pollute in states with predominantly high African‐American populations. Our analysis indicates that polluting facilities tend to choose counties with higher proportion of nonwhite populations. Per capita incomes of people living within 5‐miles of the facilities are lower than per capita incomes of people living in the host counties Contrary to the conventional wisdom, population density per square mile both within 1 mile and 5 miles of the facility are much higher than the state population densities.     

Planning for population ageing: Ensuring enabling and supportive physical-social environments – Local infrastructure challenges

Ensuring enabling and supportive environments is a key global priority in planning for population ageing. This paper examines the challenges local governments face in creating age-friendly physical-social environments. Findings from a recent study of local government and ageing in New South Wales, Australia and subsequent research are reported. The analysis reveals that local councils have differing abilities to provide age-friendly local infrastructure. Challenges are greater overall for regional, rural and fringe councils compared to metropolitan. Timely provision is greatly constrained by insufficient resources, the large scale of the task and the low priority accorded, despite the immediate need for action. A pressing requirement is demonstrated for local councils to give primacy to population ageing in their long-term strategic, asset and financial planning, and to engage in reform measures to assist in financing the cost.     

城市人口密度的中日比较及对城市研究的反思

我国学界对城市人口密度有不同认识。根据最新统计资料对中国天津、上海、广州和日本东京、大阪的人口密度研究显示,中国城市建成区人口密度普遍比日本高许多,上海约是东京的两倍,而且中心市区与周围郊区密度差异悬殊,显著的一极集中。日本城市人口分布较均匀。体现在城市住宅形态上,中国城市以集合住宅为主而日本城市以独立住宅为主。对统计数据不加分析会得出偏离实际的结论,城市研究有待精细化。     

基于人口结构视角的重庆公租房配置需求研究

人口结构是影响住房需求的重要因素之一:其中年龄结构和城乡结构对城市提供足够的住房数量提出了一个挑战,而住房数量和户型的需求又受家庭户数量和家庭结构变化的影响.为了更好地发挥重庆公租房的社会功能,本研究采用问卷调查的方式,以重庆市已经配租了的和正在等待配租的所有申请者为样本,算出了一个合理、有效、适用的公租房户型比例,这个研究数据可以用来指导接下来的公租房规划与建设.因此,研究人口结构对重庆市公租房配置需求的总量和房型结构面积影响具有重要的现实意义.     

流动人口与经济发展--基于地级市数据的研究

流动人口与经济发展关系的研究是制定地方经济发展战略的重要依据之一,也是中国目前面临中等收入阶段需要加以解决的重要问题.利用2005年全国1%人口抽样数据和地市级统计数据,采用2SLS回归分析法,本文分析了流动人口与区域经济发展的实证关系.结果表明,两者之间存在着互为因果的关系,并且相互的影响程度大致相当.流动人口每增加1%,将会使区域GDP提高0.54%.在金融危机之后,中西部地区逐渐成为中国经济增长的主力,沿海地区加工企业也逐渐向内陆转移,因而中西部地区将成为人口流动的主要区域,而流动人口的增加也会进一步加强中西部地区的经济发展.