Search results for "optimal"
showing 10 items of 706 documents
Optimization of structures with unrestricted dynamic shakedown constraints
2015
The unrestricted dynamic shakedown theory is here utilized with the aim to formulate different optimal design problems for structures mainly subjected to seismic loads. In particular, reference is made to plane frame structures constituted by elastic perfectly plastic material subjected to load combinations characterized by the presence of simultaneous fixed and seismic actions. The design problems, formulated on the ground of a statical approach, are devoted to structures with and without seismic protection devices, with special emphasis to seismic isolators. For the proposed design problem formulations different constraints are utilized; actually, for structures without protection devices…
On the optimal design of multi-stage cascaded transistor amplifiers with noise, gain and mismatch constraints
2007
The problem of evaluating the optimal performances of cascaded, unbalanced, multi-stage transistor amplifiers is addressed. In particular, a theoretically rigorous approach is proposed for the determination of a family of Optimal Design Curves (ODC's) which express the best noise-gain tradeoff that can be achieved - at each frequency and device operating condition - when a simultaneous constraint on amplifier input VSWR is accounted for. Such curves can be used as a more meaningful starting point in practical amplifier design in place of the approximate calculations so far employed for target performance or optimization goals determination.
Computer Aided Optimal Design of High Power Density EMI Filters
2016
Power density of power converter systems is becoming an increasingly stringent design constraint for a wide range of applications. Size reduction of EMI filter in power converters is an important aspect due to its significant impact on the overall converter volume and weight. In order to take on this issue, a computer aided procedure for a fast selection of optimal discrete EMI filter components and configuration is described in this paper. The proposed technique is a rule-based automatic procedure based on suitable databases that consider datasheets information of commercially available passive components (e.g. magnetic cores, capacitors). It allows the minimization of the filter's volume …
The application of AI techniques in the optimal design of multi-pass cold drawing processes
2001
Abstract In the paper the problem of optimal pass schedule design in multi-pass wire drawing process is investigated. An automatic design procedure based on an effective artificial intelligence (AI) technique, namely simulated annealing (SA), is proposed. The developed algorithm is aimed to achieve a satisfactory balance of the drawing stresses on the material along the reduction sequence, maintaining in the meantime the drawing stress at each pass below a safety value. In this way both the optimal number of passes and the optimal drawing sequence are determined. The effectiveness of the design procedure is tested through the comparison of the sequences suggested by the algorithm with a set…
Optimum design and operation of primary sludge fermentation schemes for volatile fatty acids production.
2003
This paper presents a model-knowledge based algorithm for optimising the primary sludge fermentation process design and operation. This is a recently used method to obtain the volatile fatty acids (VFA), needed to improve biological nutrient removal processes, directly from the raw wastewater. The proposed algorithm consists in a heuristic reasoning algorithm based on the expert knowledge of the process. Only effluent VFA and the sludge blanket height (SBH) have to be set as design criteria, and the optimisation algorithm obtains the minimum return sludge and waste sludge flow rates which fulfil those design criteria. A pilot plant fed with municipal raw wastewater was operated in order to …
Process parameters calibration in 3D tube hydroforming processes
2007
In tube hydroforming the concurrent actions of pressurized fluid and mechanical feeding allow to obtain tube shapes characterized by complex geometries such as different diameters sections and/or bulged zones. What is crucial in such processes is the proper design of operative parameters aimed to avoid defects (for instance shape defects or ductile fractures). The main process parameters are material feeding history (i.e. the punches velocity history) and internal pressure path during the process. In more complex three dimensional processes, also the action of a counterpunch is generally useful to reduce thinning in particular in expansion zones of the tube (i.e. T or Y shaped tubes). The g…
Scope Oriented Thermoeconomic analysis of energy systems. Part II: Formation Structure of Optimality for robust design
2010
This paper represents the Part II of a paper in two parts. In Part I the fundamentals of Scope Oriented Thermoeconomics have been introduced, showing a scarce potential for the cost accounting of existing plants; in this Part II the same concepts are applied to the optimization of a small set of design variables for a vapour compression chiller. The method overcomes the limit of most conventional optimization techniques, which are usually based on hermetic algorithms not enabling the energy analyst to recognize all the margins for improvement. The Scope Oriented Thermoeconomic optimization allows us to disassemble the optimization process, thus recognizing the Formation Structure of Optimal…
A multicriterion design of steel frames with shakedown constraints
2006
The minimum volume design of elastic perfectly plastic steel frames subjected to fixed and cyclic loads is searched in such a way that the structure remains in elastic field in serviceability conditions, while it is subjected to alternating plasticity under very strong cyclic actions, incremental and instantaneous collapse being prevented. The problem is faced on the grounds of a statical and a kinematical approach. The Kuhn-Tucker conditions of the two problems prove that they are each one the dual of the other and provide useful pieces of information about the structural behaviour. Numerical applications confirm the theoretical expectations: optimal designs turn out to be quite light, wit…
Discrete variable design of frames subjected to seismic actions accounting for element slenderness
2015
An optimal design problem formulation of elastic plastic frames under different combinations of fixed and seismic loads is presented. The optimal structure must behave elastically for the fixed loads, shakedown for serviceability conditions and prevent instantaneous collapse for fixed and high seismic loads. P-Delta effects and element buckling are considered. An appropriate modal technique is utilized. The design variables can have components in a continuous field or, alternatively, in chosen discrete sets or, yet, both kind of variables can be present. The design problem is formulated on the ground of a statical approach. The applications are related to steel frames.
Optimal design of cogeneration plants for seawater desalination
2004
Multi-stage flash (MSF) and reverse osmosis (RO) are the most common techniques for seawater desalination. A significant difference between these methodologies consists of their different energy requirements, i.e., thermal energy for MSF and mechanical energy for RO plants. The presence of both desalination systems (MSF and RO) appears to be suitable for cogeneration plants. The reject heat from the power cycle can feed an MSF section, while some power feeds the RO section and the MSF auxiliary equipment; the rest is sold to the grid. A criterion for the optimal design of such tri-functional cogeneration plants is proposed, based on exergo-economics and on profit maximization. In particular…