污泥灰替代粘土煅烧水泥熟料的~(29)Si固体高分辨核磁共振分析

城市污泥的灰分与水泥生料中粘土的成分类似,可被用作粘土的替代品煅烧生态水泥熟料,从而实现污泥的减量、无害、资源循环利用的可持续发展要求。本文用污泥灰替代粘土配置成掺量为0wt.%、3.58wt.%、7.16wt.%、10.73wt.%和14.31wt.%的生料并煅烧成熟料,再利用~(29)Si固体高分辨核磁共振技术分析五种熟料的矿物成分,通过固体核磁分峰拟合技术得出五种熟料的贝利特和阿利特的含量比值,结果表明随着污泥灰掺量的增加,熟料中贝利特含量增加,阿利特含量降低,污泥中微量元素的引入使β-C_2S更稳定,阻碍C_2S向C_3S的转化。     

A hybrid VNS approach for the short-term production planning and scheduling: A case study in the pulp and paper industry

Mathematical formulations for production planning are increasing complexity, in order to improve their realism. In short-term planning, the desirable level of detail is particularly high. Exact solvers fail to generate good quality solutions for those complex models on medium- and large-sized instances within feasible time. Motivated by a real-world case study in the pulp and paper industry, this paper provides an efficient solution method to tackle the short-term production planning and scheduling in an integrated mill. Decisions on the paper machine setup pattern and on the production rate of the pulp digester (which is constrained to a maximum variation) complicate the problem. The approach is built on top of a mixed integer programming (MIP) formulation derived from the multi-stage general lotsizing and scheduling problem. It combines a Variable Neighbourhood Search procedure which manages the setup-related variables, a specific heuristic to determine the digester's production speeds and an exact method to optimize the production and flow movement decisions. Different strategies are explored to speed-up the solution procedure and alternative variants of the algorithm are tested on instances based on real data from the case study. The algorithm is benchmarked against exact procedures.     

Estimation and diagnosis using multi-models with application to a wastewater treatment plant

Process diagnosis is still considered a challenging engineering problem. Technological and also environmental systems have complex behaviors often involving nonlinear relationships. When confronted to such systems, there is a need to build systems that can operate over a wide range of operating conditions. For that it is very attractive to appeal to a decomposition of the system model into a number of simpler linear models. This paper mainly focuses on the use of multi-models for process diagnosis. It is shown how the traditional tools of the linear automatic can be wide and applied to multi-model structures. A proportional multi-integral observer is used for fault diagnosis using banks of observers to generate structured residuals. The performances of the proposed diagnosis method are highlighted through the application to a wastewater treatment plant model (WWTP), which is an uncertain nonlinear system affected by unknown inputs.     

粗糙集理论在试卷分析中的应用

传统的试卷分析方法是采用数理统计的方法,但得到的分析指标通常不能很好地体现试题的冗余和重要程度.运用粗糙集理论,给出了一种试卷分析的新方法,较之传统的试卷分析方法,可以得到试题的冗余信息和重要度信息,反映试卷结构的合理性,使试卷分析更加合理,规范,客观.     

基于PHP的网络实时考试系统开发

文章设计了基于PHP的网络实时考试系统,分析了系统功能、结构及流程,介绍了实现考试系统的三种关键技术,包括组卷技术、加密技术以及Ajax技术,并给出部分源代码.该系统具有较强的实用性和通用性.     

DRYING PAPER IN SUPERHEATED STEAM

ABSTRACT

The industrial potential for drying paper in superheated steam has been investigated in a series of studies designed to treat paper properties - drying process relations as well as process engineering aspects. Properties measurements show that for paper made from mechanical pulps, drying in superheated steam produces a better bonded sheet which is thereby stronger and has a lower scattering coefficient. Surface properties of such steam dried paper are improved, including reduced tinting. Desorption equilibrium shows that completely dry paper can be obtained at very low superheats. Impingement drying rates can be about twice as high for drying in superheated steam as in air. A hybrid cycle was developed in which drying is partially by superheated steam impingement drying and partially by conventional cylinder drying. Preliminary design and techno-economic evaluation indicates that three factors, paper properties, dryer size and energy efficiency, in various combinations specific to each case, may provide industrial potential for this new technology for drying paper.     

课程论文在公安基础化学教学中的实践

公安基础化学课程是公安高等院校化学教育的专业基础课。为了激发学生的学习热情,提高学生的学习能力,培养学生的创新意识,我们在公安基础化学课程中开展了课程论文的教学活动,对课程论文的选题、内容、格式、考核等方面进行了具体的实践。实践的结果表明:通过开展课程论文的活动,激发了学生的学习积极性,提高了学生分析问题、解决问题的能力,达到了培养创新型公安人才的目的。     

聚氨酯乳液在纸张涂料中的应用研究

制备了十一种性能不同的乳化型聚氨酯乳液，分别配制成涂料，涂覆在原纸上，通过相应的涂布纸性能的测试，研究了聚氨酯乳液的羧基含量和交联剂影响。确定纸张涂料用聚氨酯乳液的羧基含量为１８％～２２％，交联剂以二乙烯三胺为好。     

Design‐based life cycle assessment of hazardous air pollutant control options at pulp and paper mills: a comparison of thermal oxidation to photocatalytic oxidation and biofiltration

BACKGROUND: The forest products industry produces valuable industrial chemicals, wood products, and consumer goods, but is also responsible for the emission of significant quantities of hazardous air pollutants. Although many air pollution control options are available, little is known about the overall environmental impacts of implementing each option. Therefore, a life cycle assessment (LCA) was conducted to compare energy and raw material inputs, air emissions, and environmental impacts associated with construction and operation of two air pollution control systems: regenerative thermal oxidation (RTO) with wet scrubbing and photocatalytic oxidation (PCO) with biofiltration. RESULTS: LCA results indicated that environmental impacts to resource depletion, photochemical oxidant formation, and acidification were 20% higher for the use of a RTO‐scrubber than for the PCO‐biofilter. In addition, at least 25% of the RTO impacts were due to infrastructure requirements. However, the PCO‐biofilter system was responsible for more environmental impact in categories of global warming and human toxicity, because of the packing materials required and the electricity use for the PCO reactor. CONCLUSIONS: The PCO‐biofilter system could be a promising, environmentally‐friendly alternative to traditional RTO devices, provided that this system is modified to decrease resource and energy demands. Copyright © 2008 Society of Chemical Industry     

塑料杯套造型与注塑模具结构设计

介绍花瓣式塑料杯套的造型设计,并给出了相应模具结构。详细介绍模具的冷却系统、浇注系统、合模导向和定位机构设计的方案,并给出了注塑机的选择及模具的有关校核情况。经试运行表明,本模具动作可靠,冷却均匀,排气良好,浇注系统凝料与注塑件能自动脱出,完全可保证塑料杯套的自动化生产。