This study covers the review of algorithms developed for the optimum design of steel skeletal structures from the first article published in 1960 until to date. The paper initially describes the mathematical formulati...
详细信息
This study covers the review of algorithms developed for the optimum design of steel skeletal structures from the first article published in 1960 until to date. The paper initially describes the mathematical formulation of a simple truss structural design problem. The early optimum design algorithms that were based on mathematical programming techniques where the design variables are assumed to be continuous are reviewed. The optimum design of steel framed structures necessitates the selection of steel profiles from the standard list of discrete steel sections and requires the satisfaction of design code provisions. Both mathematicalprogramming and optimality criteria techniques need more capability to produce solution to this type of optimum design problems. Soft computing techniques emerged recently provide solution directly without needing any approximation. These techniques are classified and reviewed and their use in obtaining the optimum solution of actual industrial steel design applications is given.
Global warming, environmental issues, food crisis and energy security are the main concerning problems which have triggered a sense of urgency among policymakers and development practitioners to find sustainable and v...
详细信息
Global warming, environmental issues, food crisis and energy security are the main concerning problems which have triggered a sense of urgency among policymakers and development practitioners to find sustainable and viable solutions in the area of bioenergy. Among various edible and non-edible bioenergy feedstocks specified for biodiesel production, Jatropha curcas L (JCL) and waste cooking oil (WCO) have been introduced to be promising and sustainable. In this study, an integrated hybrid approach based on a data envelopment analysis (DEA) and mathematical programming techniques is presented for the strategic design of biodiesel supply chain network in Iran. In the first phase, JCL cultivation areas are assessed according to climatic and social criteria by a unified DEA (UDEA) model. In the second phase, the locations which have achieved desired efficiency scores are considered as candidate locations for JCL cultivation within a mathematicalprogramming model developed for designing the biodiesel supply chain network. The proposed mathematicalprogramming model optimizes the numbers, locations and capacities of JCL cultivation centers, JCL seeds and WCO collection centers, bio-refineries, and distribution centers. The proposed approach is implemented in Iran for 10 years planning horizon. The results show the usefulness and efficiency of the proposed method in assisting the policymakers to take suitable strategic and tactical level decisions related to biodiesel supply chain planning. (C)2015 Elsevier Ltd. All rights reserved.
Enlarging the scope of agricultural policy analysis, with contemporary issues such as multifunctional farming, means that conventional models should be adjusted. Starting from the intrinsic nature of multifunctionalit...
详细信息
Enlarging the scope of agricultural policy analysis, with contemporary issues such as multifunctional farming, means that conventional models should be adjusted. Starting from the intrinsic nature of multifunctionality, we show that the link between farm and policies is becoming increasingly important in the general framework of model-based policy impact analysis. This argues for the use of farm-level programming models. The paper presents three mathematicalprogramming approaches, of which the choice depends on the type of problem and the availability of historical data. First is shown how normative mathematicalprogramming (NMP) can help to simulate the impact of new activities when historical data are scarce. The second approach is positive mathematicalprogramming (PMP), which allows taking both historically observed behaviour and new normative information into account. The similarities and differences between both approaches are illustrated with a simplified dairy farm model that simulates the uptake of meadow bird management. Finally, a more advanced programming technique, econometric mathematicalprogramming (EMP), is introduced combining the advantages of econometrics and programmingtechniques. Advantages and disadvantages as well as the integration with other quantitative methods are discussed for relevance and applicability in multifunctionality research. (c) 2006 Elsevier B.V. All rights reserved.
The selection of manipulated and controlled variables as well as the structure and parameters of their interconnecting controller is an important synthesis problem that has received a lot of attention from the process...
详细信息
The selection of manipulated and controlled variables as well as the structure and parameters of their interconnecting controller is an important synthesis problem that has received a lot of attention from the process control community. This paper presents a mathematicalprogramming methodology for the solution of this multifaceted synthesis problem. The method is applicable to linear or linearised nonlinear systems. In addition, a quantitative index is proposed for the estimation of the advantages in using unstructured controllers, such as model predictive controller (MPC, when compared to classical structured controllers such as multivariable proportional-integral-derivative (PID) controllers. Two case studies are presented where the potential of the method as a rigorous technique for solving the regulatory control structure selection problem for linear systems is established. (C) 2002 Elsevier Science Ltd. All rights reserved.
暂无评论