Criterion for the pollution of small rivers by domestic effluents

Translated from Izmeritel'naya Tekhnika, No. 7, pp. 54–55, July, 1990.     

A synthesis approach to distributed supervisory control design for manufacturing systems with Grafcet implementation

In supervisory control, computational complexity and implementation flexibility represent major challenges when a large number of local components compose a target system. To overcome these difficulties, we propose a formal approach to distributed control synthesis and implementation for automated manufacturing systems (AMS). We assume that the system is modelled with automata in a local modular fashion. Local control specifications are defined for each local subsystem by means of logical equations to construct local controllers (LCs). Then, global control specifications, stated as logical implications, are applied to the LCs, which allows synchronisation and cooperative interaction among the subsystems. This paper makes two contributions. First, it outlines a formal method for constructing minimally restrictive and deadlock-free distributed controllers (DCs). Second, it proposes a method for the interpretation of these DCs into Grafcet, which is a graphical modelling formalism widely used to design the controller’s dynamic behaviour for AMS. An experimental manufacturing system illustrates the approach.     

Optimal design of the two-level distributed network with dual homing local connections

To keep abreast of the ever-tightening robustness standards of communication services, we consider the topological design of the two-level network where a sufficient level of structural redundancy is imposed: the embedded backbone subnet is fully meshed and each user node is connected to two different backbone nodes. This complicated design problem for the dual homing full-mesh network is formulated as a 0-1 integer problem so that the key structural characteristics of the single homing network design model are carried over. By applying the usual dual-based solution procedure, we develop ours, which consists of three dual and one primal subprocedures. The computational experiments conducted with a variety of test problems illustrate the effectiveness of the proposed solution approach.     

A mixed-integer nonlinear program for the optimal design and dispatch of distributed generation systems

Maturing distributed generation (DG) technologies have promoted interest in alternative sources of energy for commercial building applications due to their potential to supply on-site heat and power at a lower cost and emissions rate compared to centralized generation. Accordingly, we present an optimization model that determines the mix, capacity, and operational schedule of DG technologies that minimize economic and environmental costs subject to the heat and power demands of a building and to the performance characteristics of the technologies. The technologies available to design the system include lead-acid batteries, photovoltaic cells, solid oxide fuel cells, heat exchangers, and a hot water storage tank. Modeling the acquisition and operation of discrete technologies requires integer restrictions, and modeling the variable electric efficiency of the fuel cells and the variable temperature of the tank water introduces nonlinear equality constraints. Thus, our optimization model is a nonconvex, mixed-integer nonlinear programming (MINLP) problem. Given the difficulties associated with solving large, nonconvex MINLPs to global optimality, we present convex underestimation and linearization techniques to bound and solve the problem. The solutions provided by our techniques are close to those provided by existing MINLP solvers for small problem instances. However, our methodology offers the possibility to solve large problem instances that exceed the capacity of existing solvers and that are critical to the real-world application of the model.     

Optimal design for flexible manufacturing systems: generalized analytical methods

Advanced manufacturing systems such as Flexible Manufacturing Systems (FMSs) are capital-intensive. Designing functional yet cost-effective FMSs is a challenging task because it involves the solution of a complex series of interrelated problems. In this paper, we study a design problem for FMSs that consist of multiple types of machines. Using closed queueing network models for FMSs, this problem seeks the minimum cost design subject to meeting throughput requirements. The design decisions include the number of machine groups, the number of machines for each group, the workload allocation among machine groups, the number of pallets, the number of transporters, and the batch size. Since these design decisions are highly interdependent, we present the optimum and heuristic methods that simultaneously determine them. To our knowledge, these methods are the most general analytical methods for FMS design. Development of the heuristic methods is crucial because of the time-consuming nature of the optimum method as the number of machine types increases. Computational results show that the heuristic methods are both effective and efficient.     

Optimal design of air-conditioning systems using deep seawater

Clean Technologies and Environmental Policy - This paper presents a multi-objective mixed integer linear programming problem for the optimization of seawater air-conditioning systems using deep...     

Optimal flow path design of unidirectional AGV systems

This paper describes an alternative formulation of the AGV flow path layout (FPL) problem which was first formulated by Gaskins and Tanchoco (1987) as a zero-one integer programming problem. A computationally efficient procedure is proposed which is based on the branch-and-bound technique. An algorithm for satisfying the reachability condition for nodes in the AGV flow path network is also presented. A simple illustrative example is discussed to demonstrate the procedure, and a more complex problem is also given.     

Optimal design of stationary supercapacitors storage devices for light electrical transportation systems

Recently a great interest has been paid in the relevant literature to the use of energy storage systems for the performance improvement of electrified light transit systems. In this context, the main targets are the increase of the energetic efficiency and the reduction of pantograph voltage drops. Therefore, it can be very interesting the determination of the optimal characteristics of a storage device for satisfying these objectives, both in stationary and onboard case. In this paper, this problem is approached for a sample case study, by showing that the optimal design of a stationary storage device can be regarded as a classical isoperimetric problem, whose solution is very attractive in order to determine also the optimal allocation of the storage device. For more complex configurations of the transit system, the methodology presented can be extended by solving a constrained optimization problem, which in a quite general manner is capable of matching all the assigned technical requirements. The reported simulations confirm the validity of the proposed design approach.     

Optimal design of gating systems by gradient search methods

A numerical optimization technique based on gradient-search is applied to obtain an optimal design of a typical gating system used for the gravity process to produce aluminum parts. This represents a novel application of coupling nonlinear optimization techniques with a foundry process simulator, and it is motivated by the fact that a scientifically guided search for better designs based on techniques that take into account the mathematical structure of the problem is preferred to commonly found trial-and-error approaches. The simulator applies the finite volume method and the VOF algorithm for CFD analysis. The direct gradient optimization algorithm, sequential quadratic programming (SQP), was used to solve both a 2D and a 3D gating system design problems using two design variables. The results clearly show the effectiveness of the proposed approach for finding high quality castings when compared with current industry practices.     

Optimal design and operation of automatic inspection systems in flexible industrial systems

Translated from Izmeritel'naya Tekhnika, No. 8, pp. 28–29, August, 1990.     

Linear program-based algorithm for the optimal design of wastewater treatment systems

This paper presents a new approach for the optimal design of distributed wastewater treatment networks with multiple contaminants. It consists of a two-stage solution strategy. In the first stage, a decomposition method is employed that replaces the general non-linear program (NLP) by a succession of linear programs, one for each treatment unit. In the second stage, the resulting network is used as a starting point for the solution of the general NLP by a local optimization solver. The decomposition process considers a specific substructure, where it is assumed that the wastewater streams go through the treatment units in sequence. To consider all combinations, the two-stage solution strategy is applied as many times as the number of possible sequences. This allows considering multiple and structurally different starting points, thus increasing the probability of finding global optimal solutions. The results have shown that the proposed approach can find better solutions than other approach reported in the literature, however with a drawback of being more demanding computationally. An erratum to this article can be found at     

Optimal design for resilient load‐sharing systems with nonidentical components

For system maintenance, strategic component restoration planning is an important conceptual framework for load‐sharing k‐out‐of‐n: G system. A cost‐effective treatment of failure events is imperative with the purpose of reinstating the system ability. This paper presents a new optimal design method for load‐sharing repairable k‐out‐of‐n: G system, in which a flowgraph is used in conjunction with multiresponse optimization. By introducing the concept of modular design, the system is partitioned into scalable and repairable maintenance modules. The determination of the optimal design depends on the type of system components, the module‐based system structure, and the repair rule setting. An extended flowgraph model, which links covariates into transition branches, is used for modeling the system failure evolution. With consideration of various system performance measurements as responses, multiresponse optimization with weighted principal component analysis is used to achieve an optimal design of maintenance modules as well as repair policy. The methodology presented in this paper provides an efficient way to design a system having nonidentical components and arbitrary repair time distributions with consideration of the variety of maintenance policies as well as the diversity of system operating conditions.     

Application of delay systems for ecological monitoring of industrial effluents

We examine the feasibility of designing sensitive elements for monitoring aqueous effluents of the electroplating industry based on electrodynamic delay systems.Translated from Izmeritel'naya Tekhnika, No. 6, pp. 57–60, June, 1994.     

Optimal distributed joint frequency, rate and power allocation in cognitive OFDMA systems

The problem of wireless resource management in broadband cognitive OFDMA networks is addressed. The objective is to maximise the multiple cognitive users' weighted rate sum by jointly adjusting their rate, frequency and power resource, under the constraints of multiple primary users' interference temperatures. First, based on two interpretations of the interference temperatures, the problem studied is formulated as two nonlinear and non-convex optimisation problems. Secondly, these two problems are analysed, and a centralised greedy algorithm is proposed to solve one problem, as well as a centralised algorithm based on Lagrangian duality theory for the other. The two centralised algorithms are shown to be optimal and both have polynomial time complexities. Finally, it is shown that the two centralized algorithms can be distributively implemented by introducing the idea of virtual clock. And the distributed algorithms can be interpreted as an interesting distributed negotiated secondary market approach. It is believed that the work will provide a good reference for the emerging cognitive network protocol design.     

Optimal magnet design for NMR

The author considers two difficulties inherent to computational methodology of optimal magnet design for NMR (nuclear magnetic resonance): (a) spectral methods of magnetic field analysis that would be highly accurate, fast, and general, and (b) an optimization strategy that would eliminate physically as well as numerically unstable solutions. The least-squares approximation method of zonal harmonics with iterated accuracy improvement is shown to be an effective alternative for the highly accurate spectral analysis of magnetic field in NMR applications. The principle of stability, the averaging of perturbed solutions, and Monte Carlo evolution methods are recommended for optimal magnet design in NMR. Examples of real-world magnet designs are presented     

Optimal design of multi-state weighted k-out-of-n systems based on component design

This paper presents a study on design optimization of multi-state weighted k-out-of-n systems. The studied system reliability model is more general than the traditional k-out-of-n system model. The system and its components are capable of assuming a whole range of performance levels, varying from perfect functioning to complete failure. A utility value corresponding to each state is used to indicate the corresponding performance level. A widely studied reliability optimization problem is the “component selection problem”, which involves selection of components with known reliability and cost characteristics. Less adequately addressed has been the problem of determining system cost and utility based on the relationships between component reliability, cost and utility. This paper addresses this topic. All the optimization problems dealt with in this paper can be categorized as either minimizing the expected total system cost subject to system reliability requirements, or maximizing system reliability subject to total system cost limitation. The resulting optimization problems are too complicated to be solved by traditional optimization approaches; therefore, genetic algorithm (GA) is used to solve them. Our results show that GA is a powerful tool for solving these kinds of problems.     

Crab shell-based biosorption technology for the treatment of nickel-bearing electroplating industrial effluents

This paper discusses the possible application of a biosorption system with acid-washed crab shells in a packed bed up-flow column for the removal of nickel from electroplating industrial effluents. Between two nickel-bearing effluents, effluent-1 is characterized by considerable amount of light metals along with trace amounts of lead and copper. Effluent-2 is characterized by relatively low conductivity, total dissolved solids and total hardness compared to effluent-1. Crab shells exhibited uptakes of 15.08 and 20.04 mg Ni/g from effluent-1 and effluent-2, respectively. The crab shell bed was regenerated using 0.01 M EDTA (pH 9.8, aq. NH3) and reused for seven sorption-desorption cycles. The EDTA elution provided elution efficiencies up to 99% in all the seven cycles. This, together with the data from regeneration efficiencies for seven cycles, provided evidence that the reusability of crab shell in the treatment of nickel-bearing electroplating industrial effluents is viable.     

A client-server architecture for distributed measurement systems

This paper describes a client-server architecture for the remote control of instrumentation over the Internet network. The proposed solution allows multiuser, multi-instrument sessions by means of a queueing and instrument locking capability. Client applications can be easily developed by using conventional high-level programming languages or well-assessed virtual instrumentation frameworks. Performance tests are reported; they show the low overhead due to network operation with respect to the direct control of instrumentation