Evaluation of solar water heating systems

The paper addresses itself to stochastic modeling of solar water heating systems. Solar water heating systems will be modelled in order to estimate the percentage of energy contributed by the sum to the total required load by system users. The major tool in developing the model is Chapman-Kolmogorov equation. The model takes into consideration the effect of randomness of insolation, demand for hot water, and the sequence in which they occur on the evaluation of the system performance.     

Microprocessor control of distributed storage,active solar heating systems

The present paper describes the controller design of a distributed storage solar system. A single-chip computer is used as the central unit. Four types of temperature sensor are considered and IC semiconductor sensors are shown to suit this application best. The pump and auxiliary heat supply is controlled in an on/off fashion by optically isolated relays.     

A simulation of a solar energy system for heating water

This paper presents a simulation model for evaluating the economic viability of a solar system for heating water in an apartment building. The system consists of solar collectors and a back-up oil burner. The model determines the optimal number of collectors needed and the optimal method for connecting the collectors—in series or in parallel.

The simulation results show that the solar system for heating water is more economical as the life span of the system increases, as the prices of oil increase, and as the demand for hot water increases. Furthermore, connecting the collectors in series is more economical than connecting them in parallel.     

Optimum design,redundancy and reliability of structural systems

The need for structural safety under a variety of loading and accident conditions has focused attention on redundancy, ductility and reliability of structural systems. The concepts of component reserve strength and system residual strength, system reliability and system residual reliability and their application are described. Several different structural configuration examples are illustrated in which component sizes are optimized. Design models for extreme loading and accident conditions for both brittle and ductile models are developed. System design methods are recommended.     

Optimum spacing design of grillage systems using a genetic algorithm

In this study a genetic algorithm based method is developed for the optimum design of grillage systems. The algorithm not only selects the optimum sections for the grillage elements from a set of standard universal beam sections, but also finds the optimum spacing required for the grillage system. Deflection limitations and allowable stress constraints are considered in the formulation of the design problem. Due to the fact that grillage elements are thin walled sections, warping plays an important role in their design, particularly, when they are subjected to significant torsional loading. The algorithm developed has the flexibility of including or excluding the effect of warping in the design process. Grillage structures are designed for uniformly distributed loading. The optimum spacings are determined both considering and not taking into account the effect of warping in the design. The comparison of the results shows that inclusion of warping in the design process has a significant effect on the optimum spacing.     

基于ARM的油田单井油罐太阳能加温控制器的设计

为了保证井口输油管道中原油的流动性,针对传统的电加热器和水套炉存在的热效率低、功耗大、不稳定及废气对环境造成污染等问题,提出了一套以太阳能集热器为主、热泵热水器为辅的加热系统。该系统采用温度采集卡实现10路温度信号及6路开关量信号的采集,利用三星的S3C2410 ARM控制器对太阳能集热器和热泵进行交替控制,从而实现储油罐原油的加热控制。触摸屏采用3.5英寸的TFT液晶屏,并将WINCE操作系统移植到ARM处理器,从而实现了良好的人机交互控制界面。     

Optimum linear adaptive design of dominant-type systems with large parameter variations

This paper presents a significant improvement over the hitherto available linear dominant system design techniques for guaranteeing system response within prescribed bounds, despite large plant parameter variations. Noteworthy features of the new technique are as follows. 1) The mapping of the plant parameter space into the closed-loop system space is exact and permits application to a much wider and more realistic class of problems than previously possible. 2) It is shown how the loop transmission bandwidth may be made very much smaller than in the previous designs, thus considerably extending the applicability of the dominant approach because of its drastically reduced sensitivity to internal noise.     

Methods for a network design problem in solar power systems

We consider the problem of minimizing cable connections between a central computer and a field of heliostats in the design of solar power systems. This practical task can be modeled as a p-median problem with additional constraints in a weighted graph. We compare an exact branch-and-bound method with two approximate algorithms. For the latter two methods, estimations of time complexity and accuracy are presented. Computational results are shown which should be useful in the design of such large-scale power systems.     

Optimum design of frames

In this paper optimum design of frames is discussed. Specifically, minimum weight design of steel frames in the elastic range of material behaviour is treated. The solution algorithm is designed and programmed for use on micro-computers to suit a design office environment. Stress and slenderness constraints are considered, however displacement constraints may readily be implemented. Three examples are given and the results are discussed.     

基于PIC单片机的太阳能热水器控制系统设计

文章针对太阳能热水器存在着受季节和天气的影响,提供的热水量不够、不能实现全年正常使用,设计了一个利用铂电阻、74HC595和单片机等元件,对光热、电热实现智能互补的多功能太阳能热水器控制系统。给出了太阳能热水器控制器的功能设计和原理框图,并设计出各功能模块电路原理图,分析了其设计原理和实现方法。该控制系统实现了水温、水量的测量与显示,光、电加热智能互补,自动、手动操作互补等功能。     

Optimum design of Beck''s column

The present paper treats a problem of determining the mass distribution of a cantilever column subject to a compressive follower force, i.e. Beck's column, which maximizes its critical load of dynamic stability under the constraint of a specified total mass. A considerable increase of the critical load can be achieved by taking two characteristic loads into account and maximizing them simultaneously. The present optimum design is found to be a point in the space of design variable at which the critical load varies in a discontinuous fashion. The finite element method is used as a technique for discretizing the basic equations, while the gradient projection method is used as an optimization technique. The computational algorithm is developed and some numerical examples are shown.     

Optimum design of sandwich constructions

Finite element analysis and the optimization problem of sandwich constructions are treated. The thicknesses of the face plates and the core are used as design variables. The hybrid approximation technique in combination with the dual method from mathematical programming is used. Three examples are solved using six-nodal triangular and eight-nodal quadrilateral sandwich shell elements.     

Computer simulation for a solar heating system

In this paper a simulation model for a basic solar heating system which is suitable for control and optimization studies is developed. A model for flat plate solar collectors using fluids for the heat transfer which allows the analysis of operation in great detail is presented. The simulation model for the solar collectors has also the characteristic that its inputs and outputs are quantities which are easily measurable in the real world. The effect of temperature stratification in the heat storage device model is considered by simulating two storage chambers of variable volume. The heat storage model requires relatively small time increments, a requirement which is not as stringent as that for the solar collectors. The tank's model primary variables are the easily measurable quantities of temperature and flow rates with the addition of volume as an internal variable. Weather, load and control modeling is also presented. The gradient search method is then applied to study optimal sizing of solar heating components of The University of Toledo solar house.     

Optimum design of rigidly jointed frames

In this paper a method is presented for the optimum, minimum weight design of rigidly jointed frames. The problem is formulated using the matrix displacement method for which the design variables are not only the areas of members but also the displacements of joints. Both the stress and displacement requirements, as stated in B.S. 449, are taken into consideration. The problem turns out to be one of non-linear programming. This is linearised by using the first two terms of a Taylor expansion. To ensure a feasible solution move limits are employed so that the iteration procedure avoids the reduction of vital structural variables to zero. The design procedure developed do not require the structural analysis equations to be solved during the optimisation process. Examples are given to demonstrate the method.     

Optimum shape design of rotating disks

This paper deals with optimum shape design of the rotating disks by nonlinear programming method. The shape of the cross section is defined by 5th degree polynomial which is completely determined by the boundary conditions and four design variables. The stress analysis of the disk is carried out by finite element method using isoparametric elements. The optimization technique used is with improved movelimit method of sequential linear programming. Progress of optimization is investigated with three different objective functions. After preliminary studies a weighted objective function is selected for detailed investigation. Optimum shapes are obtained for different speeds and for different fit pressures from hub. The results are presented in non-dimensionalised form.     

Optimum quantization in dynamic systems

In this paper the problem of optimally designing a quantizer imbedded in a closed-loop dynamic system is considered. The criterion for the design is that the overall system performance as expressed by a variational criterion is optimized. The function of quantization is thus related to the functions of control and estimation that are performed in the system. First, a procedure is described for optimally designing a quantizer in a static open-loop system, where the design criterion is the expected value of a function of the instantaneous error between the input and output of the quantizer. This procedure reduces the search over all quantizer parameters to an iterative search over a single parameter. Next, the existing methods for finding the optimal design of a quantizer imbedded in a dynamic system are reviewed. The most general method found in the literature involves a combination of dynamic programming with an exhaustive search for all quantizer parameters. The computational requirements of this procedure are quite large even for low-order systems with few quantizer parameters. Finally, a new result is presented that leads to greatly reduced computational requirements for the dynamic system case. It is shown that under certain conditions an overall optimum system design is obtained by first optimizing the system with all quantizers removed and then applying the procedure for the static open-loop case mentioned above. This result is analogous to the separation of the functions of estimation and control that occurs under similar conditions. The computational savings over the existing procedures are very extensive, and the new procedure is computationally feasible for a large class of practical systems.     

Optimum design of lattice-columns for buckling

This paper is about the problem of optimization of bracing columns—height of the parallel chords, cross-sectional areas of the chord and bracing and area moments of inertia of the chord and bracing. Optimization parameters have been determined by Lagrange’s multipliers method—inequality constraint functions. Total mass of the construction has been selected as the objective function. Criterions of buckling (general buckling of the bracing column, local buckling of the chord and local buckling of the bracing diagonal) and criterion of deformation are used as the constraint functions. Numerical examples are performed by usage of the obtained theoretical solutions.     

Optimum control of irrigation water application

The problem of controlling soil water within the root zone of irrigated crops to minimize the expected loss is examined. Control is accomplished by scheduling the amount of and timing irrigations to replenish the soil water reservoir depleted by the crop's water consumption. Actual evapo-transpiration rates are a function of the prevailing soil water level and the evaporative demand, which may be considered to be either deterministic or probabilistic. For crops grown on a particular soil, an optimum soil water level is defined as the lowest soil water level above which crops are not stressed. The reduced yield of a crop is related to its growth stage and to the amount and duration that the soil water content is below this optimum value.Existing inventory models are adapted for the purpose of determining the optimal irrigation policy, that is, the timing and amount of water application that result in the minimum irrigation cost to the farmer. Solutions to complex decision-making problems are currently available for a variety of irrigation situations.     

参数自适应粒子群算法的给水管网优化研究

针对粒子群算法在解决给水管网优化问题时存在容易陷入局部最优的缺点,通过分析粒子的运动轨迹和相似程度,提出一种参数自适应粒子群算法。该算法利用种群粒子与期望粒子之间相似度的大小,动态调整算法参数,平衡算法全局和局部搜索能力,利用分期变异策略增加种群多样性,保证算法收敛于全局最优值。将改进算法用于优化汉诺塔管网和纽约管网2个经典的管网案例,证明算法可以有效应用于给水管网这类组合优化问题。将该算法优化实际的管网改扩建案例,结果表明,所提出的算法具有更好的寻优性能和收敛性能。