An extension of ASM2d including pH calculation

This paper presents an extension of the Activated Sludge Model No. 2d (ASM2d) including a chemical model able to calculate the pH value in biological processes. The developed chemical model incorporates the complete set of chemical species affecting the pH value to ASM2d describing non-equilibrium biochemical processes. It considers the system formed by one aqueous phase, in which biochemical processes take place, and one gaseous phase, and is based on the assumptions of instantaneous chemical equilibrium under liquid phase and kinetically governed mass transport between the liquid and gas phase. The ASM2d enlargement comprises the addition of every component affecting the pH value and an ion-balance for the calculation of the pH value and the dissociation species. The significant pH variations observed in a sequencing batch reactor operated for enhanced biological phosphorus removal were used to verify the capability of the extended model for predicting the dynamics of pH jointly with concentrations of acetic acid and phosphate. A pH inhibition function for polyphosphate accumulating bacteria has also been included in the model to simulate the behaviour observed. Experimental data obtained in four different experiments (with different sludge retention time and influent phosphorus concentrations) were accurately reproduced.     

A framework for rapid local area modeling for construction automation

Rapid 3D positioning and modeling in construction can be used to more effectively plan, visualize, and communicate operations before execution. It can also help to optimize equipment operations, significantly improve safety, and enhance a remote operator's spatial perception of the workspace. A new framework for rapid local area sensing and 3D modeling for better planning and control of construction equipment operation is described and demonstrated. By combining human-assisted graphical workspace modeling with pre-stored Computer-Aided Design (CAD) models and simple sensors (such as single-axis laser rangefinders and remote video cameras), modeling time can be significantly reduced while potentially increasing modeling accuracy.     

Decomposing regional productivity growth using an aggregate production frontier

The main contribution of this paper is the implementation of a new model which combines the two parametric approaches most commonly used in the productivity literature: fixed effects and stochastic frontiers. This allows us to discuss whether it is better to use average or frontier functions to estimate regional productivity. The empirical section uses panel data of Spanish regions over the period 1980–1995. Additionally, we calculate and decompose total factor productivity growth for the Spanish regions.     

楼梯升降机简介

介绍楼梯升降机的结构、参数、特点、具体应用和选购指南。     

加填料A2O/混凝沉淀法处理酒店污水

深圳市某酒店采用加填料A^2O／混凝沉淀法对其排水进行处理。运行表明，该工艺处理效果好，出水水质达到了GB 8978-1996的一级标准，处理成本为1．14元／m^3。     

Simple monopoly price theory in a spatial market

One of main conclusions drawn by prior studies is that in a spatial market, the shape of the demand function can fully determine whether one simple pricing policy is superior to another either on the basis of the firm’s preference or social desirability while there is one assumption that is generally stipulated, namely, that the fixed market area assumption under which the market area is exogenously determined and remains the same under alternative pricing policies. In order to fully understand the impact of a demand function, this paper attempts to reexamine the relative economic advantages between two simple spatial pricing policies in a world with variable market area, that is, the market area is endogenously determined the price charged. We show that the fixed market area assumption is valid only where demand is linear, but no longer holds where demand is nonlinear. Moreover, and more importantly, we show that in a world with variable market area, some conclusions drawn by prior studies on the relative economic benefits of two pricing policies cannot remain valid. The main conclusion of this paper is that even the relative economic benefits of two simple spatial pricing policies is concerned, the impact of economic space is significant.

Homogeneous iron-catalyzed photochemical degradation of muconic acid in water

Iron photochemical oxidation has been used to remove muconic acid from water. Two different light systems were used: black lamps and solar irradiation. The effect of iron concentration, intensity of incident radiation, pH and presence of oxalic acid was investigated. The first two variables yield positive effects on the removal rate of muconic acid while higher efficiency was achieved at pH 3. Oxalic acid enhances the oxidation rate because of the formation of photoactive ferrioxalate ion. Stoichiometric results indicated formation of two hydroxyl radicals to degrade 1 mol of muconic acid. At similar experimental conditions, initial oxidation rates of muconic acid were higher when solar light was used to irradiate the aqueous solutions, although in this case, the oxidation process is stopped because of the consumption of photoactive species.     

基于J2EE的电力企业物资管理系统

基于J2EE的某电力企业物资管理系统,采用客户层、Web层、业务逻辑层及企业信息系统层四层结构.功能模块包括仓库管理、库存核算、合同管理、计划管理、统计报表及决策支持六部分.系统由IBM提供服务器平台,以创建EJB及Web组件、配置及部署J2EE应用完成其应用程序,最后通过报表打印及安全控制实现物资管理.     

The centralization index: A measure of local spatial segregation

Segregated areas may occur around an attractive park or a waste incinerator, but the magnitude and group membership of the people in closest proximity will likely be difierent. We therefore introduce a local segregation measure that can be applied to any location within a metropolitan area, and that can identify the group that is relatively more concentrated around that reference location. We further introduce an inference approach to identify the statistical significance of a particular segregation value. In an exploratory setting the index can be used to generate a map of hot spots, and seed the question: “why is this group significantly concentrated around that location?”