CEMAT软件在水泥行业的应用

介绍了两种DCS控制系统编程方式:常规编程方式和CEMAT软件编程方式,CEMAT软件是针对水泥行业的过程控制系统,软件包含了水泥厂所有类型设备的控制程序功能块和相应功能块操作面板。通过两种编程方法的比较来体现CEMAT软件编程的方便快捷及自动生成设备运行信息、报警信息、操作记录的特点。     

Approximate dynamic programming based approach to process control and scheduling

Multi-stage decision problems under uncertainty are abundant in process industries. Markov decision process (MDP) is a general mathematical formulation of such problems. Whereas stochastic programming and dynamic programming are the standard methods to solve MDPs, their unwieldy computational requirements limit their usefulness in real applications. Approximate dynamic programming (ADP) combines simulation and function approximation to alleviate the ‘curse-of-dimensionality’ associated with the traditional dynamic programming approach. In this paper, we present the ADP as a viable way to solve MDPs for process control and scheduling problems. We bring forth some key issues for its successful application in these types of problems, including the choice of function approximator and the use of a penalty function to guard against over-extending the value function approximation in the value iteration. Application studies involving a number of well-known control and scheduling problems, including dual control, multiple controller scheduling, and resource constrained project scheduling problems, point to the promising potentials of ADP.     

Mixed-integer programming approach for the synthesis of integrated process flowsheets

This paper discusses the problem of developing algorithmic methods for synthesizing chemical processes. It is shown that mixed-integer programming is the natural underlying tool for these types of methods. Mixed-integer linear programming models are reviewed for utility systems, heat-recovery networks and total processing systems. Various other applications are reviewed to show the versatility and scope of these types of techniques, as well as the shortcomings when other approaches are used. A brief outline for handling explicitly nonlinearities is also presented.     

基于逻辑与启发性知识的MINLP过程综合方法

提出了一种系统化的基于逻辑与启发性知识的MINLP过程优化综合方法 .该方法将超结构图的拓扑结构分解成特定的几种设备连接类型 ,通过组合形成基于逻辑的混合整数规划模型 ,克服了数学规划法在建模方面所存在的不直观、难于系统化地实现、复杂的超结构模型难于建立等缺点 .模型中还以硬逻辑或启发的形式引入工程经验 ,减小了搜索空间 ,加快了求解速度 .通过化工厂公用工程系统综合的实例 ,将本方法与传统的层次分解法、数学规划法进行了比较 ,证明了其实用性和优越性     

Computational linguistics: A new tool for exploring biopolymer structures and statistical mechanics

Unlike homopolymers, biopolymers are composed of specific sequences of different types of monomers. In proteins and RNA molecules, one-dimensional sequence information encodes a three-dimensional fold, leading to a corresponding molecular function. Such folded structures are not treated adequately through traditional methods of polymer statistical mechanics. A promising new way to solve problems of the statistical mechanics of biomolecules comes from computational linguistics, the field that uses computers to parse and understand the sentences in natural languages. Here, we give two examples. First, we show that a dynamic programming method of computational linguistics gives a fast way to search protein models for native structures. Interestingly, the computational search process closely resembles the physical folding process. Second, linguistics-based dynamic programming methods are also useful for computing partition functions and densities of states for some foldable biopolymers - helix-bundle proteins are reviewed here. In these ways, computational linguistics is helping to solve problems of the searching and counting of biopolymer conformations.     

基于带补偿随机规划的蒸汽动力系统优化设计

在蒸汽动力系统优化设计中,考虑不确定因素的优化策略能避免基于确定性设计策略的保守设计,并能针对不确定因素的实现提出相应的调度调节策略.本研究分析了蒸汽动力系统设计包含的不确定因素的特性及其对蒸汽动力系统优化目标和约束条件的影响.不确定因素的表达分成两类:基于时间变化表达和基于发生概率表达.对基于时间变化表达的因素,转化为多周期问题进行处理;对外部工艺过程变化引起的汽电需求不确定波动等基于发生概率表达的因素,应用随机规划策略,补偿不确定参数的实现可能引起的约束背离.基于本研究建立的多周期带补偿的二阶段随机规划MILP模型,求解蒸汽动力系统结构,同时优化调度调节策略,用调节决策和惩罚不足应对汽电需求等不确定因素的实现,实现系统安全稳定运行和经济效益最优.     

Exxon experience with large scale linear and nonlinear programming applications

Exxon has been a large user of linear programming since its introduction. Exxon's primary large scale math programming system has evolved to also include facilities for sucessive linear programming and mixed integer programming. Some of Exxon's other math programming tools for quadratic programming and succesive quadratic programming are also described in this paper. Results of a recent study conducted to compare the performance of Exxon's succesive linear programming and successive quadratic programming techniques with the reduced gradient technology employed in other programs are presented.     

Optimal supply chain design and operations under multi‐scale uncertainties: Nested stochastic robust optimization modeling framework and solution algorithm

Although strategic and operational uncertainties differ in their significance of impact, a “one‐size‐fits‐all” approach has been typically used to tackle all types of uncertainty in the optimal design and operations of supply chains. In this work, we propose a stochastic robust optimization model that handles multi‐scale uncertainties in a holistic framework, aiming to optimize the expected economic performance while ensuring the robustness of operations. Stochastic programming and robust optimization approaches are integrated in a nested manner to reflect the decision maker's different levels of conservativeness toward strategic and operational uncertainties. The resulting multi‐level mixed‐integer linear programming model is solved by a decomposition‐based column‐and‐constraint generation algorithm. To illustrate the application, a county‐level case study on optimal design and operations of a spatially‐explicit biofuel supply chain in Illinois is presented, which demonstrates the advantages and flexibility of the proposed modeling framework and efficiency of the solution algorithm. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3041–3055, 2016     

Applications of nonlinear programming to detergent formulations

Designed experiments have been used to secure orthogonal data in a typical light duty liquid detergent system. Regression analyses of the data have provided prediction equations relating composition to performance and physical properties for formulations in this system. The use of these equations in a nonlinear programming computer optimization program is described, illustrated by examples taken from a limited subsystem wherein two of the six components are held constant. Costs, types and uses of such optimization procedures are considered. One of seven papers being published from the Symposium, “Computer Systems and Applications in the Oil and Fat Industry” presented at the ISF-AOCS World Congress, Chicago, September 1970.     

Einsatz von programmierbaren Taschenrechnern für verfahrenstechnische Berechnungen

Using of programmable pocket-calculators for process engineering calculations . Part of a chemical engineer's daily work are repeated calculations to illustrate special relations. Suitable for this purpose are programmable pocket computers, which allow easy and quick programming by the user. This contribution gives brief instructions for creation of short and more complex programs in addition to those found in the user's manual. Independently of calculator type and nature of the problem, the single steps required to get a complete program are described. Using a special example from chemical engineering, the optimal pathway from the algorithm to the program listing is shown for two calculator types.     

Multiperiod Optimization for Production Planning of Petroleum Refineries

Production planning has been the focus of many articles in the mathematical programming literature. In particular, successful operation of oil companies depends on systematic decisions over complex logistics. The present article focuses on the decision-making process involved in petroleum production planning. The proposed model is based on a nonlinear programming formulation that was developed to plan production over a single period. First, the model incorporates multiple planning periods and the selection of different crude oil types. Uncertainty related to petroleum and product prices as well as demand is then included as a set of discrete probabilities. Finally, crude oil handling constraints are added. The resulting models are mixed integer nonlinear programs (MINLP), which were successfully applied to a real-world case at the Petrobras REVAP refinery. Problems of up to 19 time periods and up to five scenarios were solved to optimality.     

Multiperiod Optimization for Production Planning of Petroleum Refineries

Production planning has been the focus of many articles in the mathematical programming literature. In particular, successful operation of oil companies depends on systematic decisions over complex logistics. The present article focuses on the decision-making process involved in petroleum production planning. The proposed model is based on a nonlinear programming formulation that was developed to plan production over a single period. First, the model incorporates multiple planning periods and the selection of different crude oil types. Uncertainty related to petroleum and product prices as well as demand is then included as a set of discrete probabilities. Finally, crude oil handling constraints are added. The resulting models are mixed integer nonlinear programs (MINLP), which were successfully applied to a real-world case at the Petrobras REVAP refinery. Problems of up to 19 time periods and up to five scenarios were solved to optimality.     

Designing heat exchanger networks for existing chemical plants

New targets for the heat exchanger network synthesis problem, which account for both heating and power needs, are defined. Especially useful when updating existing facilities, the proposed targets stand for both the maximum heat flow to be recovered and the types and number of heating utilities to be allocated if all plant energy requirements are to be satisfied at the lowest fuel cost. The new goals are computed by solving a small-scale nonlinear programming problem introduced in this paper. Accounting for them, a heat exchanger network involving a low number of units is synthesized using the transportation formulation¹. The results clearly show the economic disadvantages of recycling process heat beyond a certain limiting value, unless bottlenecks in the current steam-power system, precluding further fuel savings, are removed.     

Programming of macro/micro scale information on shape memorizing polyvinyl acetate film

The shape memory behavior of polyvinyl acetate (PVAc), both at macroscale and microscale, is presented. PVAc films exhibited excellent efficiency in programming macroscale deformation. Cyclic tensile tests on PVAc films revealed the importance of molecular weight in programming macroscale deformation in film. PVAc film with the highest molecular weight (～228 kDa) exhibited maximum durability in programming macroscale deformation. This gives an important insight to the discovery of new shape memory polymers since chain entanglements in high molecular weight glassy polymers can impart shape memory behavior. In addition, such shape memory behavior can be exploited to imprint and tune microscale patterns on the film. Microprismatic patterns were embossed and programmed on shape memorizing PVAc films. Two different test methodologies were used to study the programmability of patterns on PVAc films. Pattern programming was significantly affected by the method used. In both cases, recovery time and temperature were two important parameters to determine the efficiency of programming. In addition, optical properties of PVAc films could be switched between reflective and transparent by programming patterns on the surface of the film. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44659.     

THE MINIMUM OF TOTAL AVAILABLE ENERGY (ENERGY) DISSIPATION IN THE MULTISTAGE FLUIDIZED WET BEDS

This article represents a second half of the work in optimization of the fluidized drying and moistening processes by the method of dynamic programming. The problem considered in Part I concerns the case of fluidized drying and moistening in the continuous processes for the variable inlet gas temperature. In this work, the generalized aspect of the continuous and multistage adiabatic processes for the case when the decision variables on the stage are gas enthalpy, gas humidity and dry gas flow rate, is considered. The continuous processes are considered here only as a limiting case of the multistage ones.

The two types of the thermodynamic performance indexes based on the idea of energy as a thermodynamic measure of the substance value are considered. The first type is related to the economic costs of production and the second to the overall economic costs. The equivalency of the optimization results for either of the two types of energy costs is discussed- Also, the nature of the optimal trajectories and decisions is considered.     

PLC上位机监控软件的开发

为提高硫化机控制水平，采用电阻式触摸平板电脑为上位机与PLC相结合。系统设计主要包括各监控画面的设计和上位机与PLC之间的通信设计，监控主画面设计成包含所有操作员需要了解的数据。实时曲线画面为圆盘型和直线型两种，上位机与PLC之间的通信采用VB6.0编程，实际运行证明状态良好。     

Protein fold comparison by the alignment of topological strings

Using the definitions of protein folds encoded in a text string,a dynamic programming algorithm was devised to compare theseand identify their largest common substructure and calculatethe distance (in terms of the number of edit operations) thatthis lay from each structure. This provided a metric on whichthe folds were clustered into a ‘phylogenetic’ tree.This construction differs from previous automatic structureclustering algorithms as it has explicit representation of thestructures at ‘ancestral’ branching nodes, evenwhen these have no corresponding known structure. The resultingtree was compared with that compiled by an ‘expert’in the field and while there was broad agreement, differenceswere found that resulted from differing degrees of emphasisbeing placed on the types of operations that can be used totransform structures. Some concluding speculations on the relationshipof such trees to the evolutionary history and folding of theproteins are advanced. Received June 19, 2003; revised September 13, 2003; accepted October 21, 2003     

Programming of Embryonic Development

Assisted reproductive techniques (ART) and parental nutritional status have profound effects on embryonic/fetal and placental development, which are probably mediated via “programming” of gene expression, as reflected by changes in their epigenetic landscape. Such epigenetic changes may underlie programming of growth, development, and function of fetal organs later in pregnancy and the offspring postnatally, and potentially lead to long-term changes in organ structure and function in the offspring as adults. This latter concept has been termed developmental origins of health and disease (DOHaD), or simply developmental programming, which has emerged as a major health issue in animals and humans because it is associated with an increased risk of non-communicable diseases in the offspring, including metabolic, behavioral, and reproductive dysfunction. In this review, we will briefly introduce the concept of developmental programming and its relationship to epigenetics. We will then discuss evidence that ART and periconceptual maternal and paternal nutrition may lead to epigenetic alterations very early in pregnancy, and how each pregnancy experiences developmental programming based on signals received by and from the dam. Lastly, we will discuss current research on strategies designed to overcome or minimize the negative consequences or, conversely, to maximize the positive aspects of developmental programming.