A discretization-based approach for the optimization of the multiperiod blend scheduling problem

In this paper, we introduce a new generalized multiperiod scheduling version of the pooling problem to represent time varying blending systems. A general nonconvex MINLP formulation of the problem is presented. The primary difficulties in solving this optimization problem are the presence of bilinear terms, as well as binary decision variables required to impose operational constraints. An illustrative example is presented to provide unique insight into the difficulties faced by conventional MINLP approaches to this problem, specifically in finding feasible solutions. Based on recent work, a new radix-based discretization scheme is developed with which the problem can be reformulated approximately as an MILP, which is incorporated in a heuristic procedure and in two rigorous global optimization methods, and requires much less computational time than existing global optimization solvers. Detailed computational results of each approach are presented on a set of examples, including a comparison with other global optimization solvers.     

On the tuning of predictive controllers: Application of generalized Benders decomposition to the ELOC problem

This work investigates the computational procedures used to obtain global solution to the economic linear optimal control (ELOC) problem. The proposed method employs the generalized Benders decomposition (GBD) algorithm. Compared to the previous branch and bound approach, a naive application of GBD to the ELOC problem will improve computational performance, due to less frequent calls to computationally slow semi-definite programming (SDP) routines. However, the reverse-convex constraints of the original problem will reappear in the relaxed master problem. In response, a convexification of the relaxed master constraints has been developed and proven to preserve global solution characteristics. The result is a multi-fold improvement in computational performance. A technological benefit of decomposing the problem into steady-state and dynamic parts is the ability to utilize nonlinear steady-state models, since the relaxed master problem is free of SDP type constraints and can be solved using any global nonlinear programming algorithm.     

基于遗传算法的高职化工院校排课系统的设计与实现

排课问题是一个有约束的、多目标的组合优化问题,并且已经被证明是一个NP完全问题。遗传算法是一种随机搜索算法,非常适合于解决NP问题。本文将遗传算法应用于求解课表问题,采用优化编码结构组合的方法减少排课冲突,降低算法的复杂度;对排课问题的关键参数进行量化分析,针对染色体编码完成各个遗传算子的设计和开发任务,最后集成排课的整体优化算法。     

An effective method for the explicit solution of sequential problems on the real line

A general method for solving optimal stopping problems for continuous-time Markov processes on the real line is developed. The basic idea is to first study an auxiliary problem for the two-dimensional process consisting of the underlying Markov process and its running maximum. It turns out that this auxiliary problem is much easier to solve using standard methods such as the monotonicity of the problem, and an optimal strategy in the class of threshold times can be found. The optimality of the time carries over to original problem. This two-step procedure gives a unifying approach for solving problems from different fields such as mathematical finance and sequential analysis.     

Analysis of the dependence of the stress state of cermet dentures on the sizes of the carcass span and bridges

A solution of the problem of rational design of cermet dental bridges is presented. An analysis of the stress-strain state and a computer-aided solution of the boundary nonuniform elastic-plastic problem give the proportion of the bridge span size to the height of the bridges of the metallic carcass at which the denture functions reliably up to the appearance of irreversible changes in it (cleavages and cracks of the ceramic coating).     

井间地震在HJ油田精细油藏描述中的应用及效果分析

H J油田存在砂体横向非均质性强,微小构造发育,油田采出程度低、采油速度低等问题。为进一步解决该油田的采收率问题,在工区内开展了井间地震技术试验,通过对井间地震资料储层、小断层综合解释,以及对工区储层的反演分析,指出砂体间的横向发育不连续及小断层分隔形成的小构造是造成H 73-H 49井区动态矛盾的主要原因。并且本次研究对井间地震资料的应用效果进行了分析。     

浅论塑料门窗行业存在的问题及解决办法

主要介绍塑钢门窗在中国的发展历史及在发展过程中存在的主要问题，分析了产生问题的原因，并从宏观角度提出了解决办法。     

用乙二醛改善柠檬酸防皱效果的探讨

介绍了柠檬酸用无甲醛防皱整理的研究现状、机理、以及存在的问题,并对如何解决问题进行了探讨研究.     

鲁奇MTP工艺精馏塔再沸器控制方式的优化

针对鲁奇MTP工艺在大唐多伦煤化工有限公司实际运行过程中精馏塔出现的灵敏板温度滞后、疏水器流通量不足的问题,相应对再沸器蒸汽侧与凝液进行了两次改造,从根本上解决了再沸器控制方式对装置长周期稳定运行的制约。     

Studies of distributed parameter systems: Decoupling the state-parameter estimation problem

The problem of state-parameter estimation is considered in terms of decoupling the estimation procedure. First, the theoretical preliminaries necessary for the mathematical statement of the problem are defined. Then using the extended Kalman filter (EKF) approach, the state and parameter are estimated by applying the solution techniques to a distributed parameter system. Next, the state estimation problem is decoupled from the parameter estimation problem and by using a numerical example, the advantage of this decoupling procedure is demonstrated. The numerical results show that convergence can be improved when this decoupling procedure is employed. The effect of the location of the measurements on the estimation problem is also analysed in this work. The results show that the convergence of the problem depends on the location as well as the number of measurements.     

寒冷地区快干汽车涂料喷涂“流挂”分析及解决方案

重点分析了寒冷地区丙烯酸改性醇酸类各色快干汽车涂料喷涂"流挂"缺陷产生的主要原因及相应解决方案。试验结果显示:在合适的树脂体系基础上,提高颜料含量,增加一次成膜厚度;添加合适的防流挂助剂及提高涂膜表面干燥速度的溶剂体系都有助于改善快干汽车涂料在约-30℃的寒冷地区的涂膜"流挂"缺陷。     

浅谈ABS塑料件涂装质量的提升

通过对公司目前ABS件涂装时存在的涂膜缺陷,从毛坯注塑问题、毛坯材质问题及施工产生的涂膜问题3方面进行分析,采取有效措施,从而提高ABS件涂装质量。     

炼厂生产计划优化模型

This article addresses a production planning optimization problem of overall refinery. The authors formulated the optimization problem as mixed integer linear programming. The model considers the main factors for optimizing the production plan of overall refinery related to the use of run-modes of processing units. The aim of this planning is to decide which run-mode to use in each processing unit in each period of a given horizon, to satisfy the demand, such as the total cost of production and inventory is minimized. The resulting model can be regarded as a generalized lot-sizing problem where a run-mode can produce and consume more than one product. The resulting optimization problem is large-sized and NP-hard. The authors have proposed a column generation-based algorithm called branch-and-price （BP） for solving the interested optimization problem. The model and implementation of the algorithm are described in detail in this article. The computational results verify the effectiveness of the proposed model and the solution method.     

焦炉煤气制尿素工艺中合成气不足的解决方案

简述了剩余焦炉煤气综合利用的途径,分析了在不同结焦时间下的合成气量分配情况,针对由于结焦时间较长低负荷工况下出现合成气量不足的情况提出了解决措施,根据提出的解决措施制定了设想工艺方案,采用UGI炉气化技术工艺造气来解决合成气不足的问题较为现实,整体工艺方案的预计投资约1000万元。     

TAC薄膜生产过程中湿膜剥离问题技术探讨

TAC薄膜作为偏光板的内保护膜用于液晶显示器。近年来,由于市场需求的不断扩大以及迫于日趋激烈的市场竞争,迫使厂商积极探索降低成本、提高效率的技术途径,比如100m/min以上的高车速,使用廉价的木浆纤维素部分替代价格昂贵的棉浆纤维素等等。而这都有可能引发湿膜"剥离问题"的产生,出现湿膜局部残留在钢带,或者剥离困难导致残品等现象,并由此导致生产适应性整体下降。本文试图通过对"剥离问题"的分析、因素归集及实验验证,继而对TAC制膜过程中的"湿膜剥离问题"进行技术探讨。     

故障诊断技术在空气压缩机故障诊断中的应用

尼龙厂新醇酮装置空气压缩机为离心压缩机,在投入运行后,发现低压缸转子振值过高,为了找出转子振值过高的原因,并有针对性的解决问题,利用中国石油在线监测系统,对该空气压缩机进行状态监测,做出相应的频谱图,与各种故障特征进行对比。应用设备故障诊断技术对监测所得数据和图表进行分析,认为转子振值过高的原因是由于转子质量不平衡造成的,可以利用现场动平衡技术,即可将振值由50.8μm/60.5μm降到18.2μm/20.0μm,解决了空气压缩机转子振动问题。     

Optimization for the minimum reaction time of pet esterification

We have investigated the direct esterification reaction between terephthalic acid (TPA) and ethylene glycol (EG) in semi-batch reactors, the first stage process for making polyethylene terephthalate (PET), to get optimum conditions for the minimum reaction time. An independent-variable-minimization problem, i.e., a free-end-time/fixed-end-point problem, has been formulated for the system, and then converted to a dependent-variable-minimization (fixed-end-time/ free-end-point) problem by a coordinate transformation, for the latter problem readily yields to established solution methods. We have solved this reformulated problem to obtain the optimal temperature profiles in the reactor required for the minimum reaction time, by iteratively improving the temperature (manipulating variable) profile using the Pontryagin’s minimum principle. The results prove that the method employed here successfully finds an optimal solution for the PET esterification process. The reduction of the reaction time realized following this optimal temperature profile in the reactor was, however, found to be smaller than expected, due to the approximating assumptions of neglecting the solubility equation of TPA in the model. The results obtained using a more improved model of the system will be reported in the future.     

应用涂装工艺解决设备的密封问题

简要介绍了一种应用涂装工艺解决设备密封问题的新方法,采用该方法不但满足了设备对真空度的要求,而且与常规的用密封胶堵漏的方法相比较,具有使用寿命长,密封效果好等特点,在解决设备的密封问题时,具有一定的推广价值。     

双组分水性木器涂料抗压痕问题的研究与探讨

提出了当前双组分水性木器涂料在家具生产或运输过程中存在的压痕问题,并介绍了压痕产生的外部环境,分析了压痕产生的原因,认为解决压痕问题的关键在于改变涂膜的内部结构。并在水性体系中引入了异氰酸酯—紫外光双重固化交联的方法,使问题得到较好的解决。     

Method of calculating the bed combustion of a solid fuel coke residue

An approximate method of solving the steady-state problem of the bed combustion of a solid fuel coke residue is proposed. The method is based on splitting the initial problem into thermal and chemical problems. The former represents the problem on the hydrodynamics and heat transfer in a blown heat-generating granular bed. The latter is the problem on the chemical conversion of a mixture of reactants in a specified temperature field. These auxiliary problems are combined into an iteration cycle to match their solutions. The model problem on the combustion of a milled peat coke residue was calculated for the cocurrent and countercurrent process schemes. The bed combustion of coke is calculated for the experimental conditions published in the literature. The calculated results are compared with the experimental data obtained under these conditions.