Search results for "optimal design"
showing 10 items of 114 documents
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…
On the Theoretical Limits of Noise-Gain-Mismatch Tradeoff in the Design of Multi-Stage Cascaded Transistor Amplifiers
2007
The problem of evaluating the limit performances of cascaded single-ended 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 (maximum optimal) noise-gain tradeoff that can be achieved - at each operating frequency - when a simultaneous constraint on amplifier input VSWR is accounted for.
Multiobjective design of distributed reactive power production in a deregulated electric market
2005
Abstract Reactive flows compensation optimal design for losses reduction in MV automated distribution systems is a problem deeply studied in literature. In this paper, the design problem is formulated considering the new deregulated energy market. These new operational conditions allow the MV grid operator to consider the generation of reactive energy also as a service that can be sold to the transmission system above. In this case, the transmission system would be helped in all the working conditions in which a strong modulation of the reactive flow through the HV/MV node is required. Then, for the MV grid operator, the compensation system optimal design problem is therefore that of the se…
Banki-Michell Optimal Design by Computational Fluid Dynamics Testing and Hydrodynamic Analysis
2013
In hydropower, the exploitation of small power sources requires the use of small turbines that combine efficiency and economy. Banki-Michell turbines represent a possible choice for their simplicity and for their good efficiency under variable load conditions. Several experimental and numerical tests have already been designed for examining the best geometry and optimal design of cross-flow type machines, but a theoretical framework for a sequential design of the turbine parameters, taking full advantage of recently expanded computational capabilities, is still missing. To this aim, after a review of the available criteria for Banki-Michell parameter design, a novel two-step procedure is de…
Costructal law, exergy analysis and life cycle energy sustainability assessment: an expanded framework applied to a boiler
2020
Purpose Life cycle sustainability assessment (LCSA) is one of the most relevant tools delving in sustainability science, based currently on the triple bottom line idea that is defined as the contemporary implementation of the three tools of life cycle assessment (LCA), life cycle costing (LCC) and social life cycle assessment (S-LCA). The methodology is currently being applied to a wide set of products and systems. However, as per in the large interest towards energy-related products, the sustainability assessment of energy systems—in particular those where fluid streams are used—could be more effective if some further stages could be included in the analysis, i.e. a process level analysis …
Optimal design of CHCP plants in the civil sector by Thermoeconomics
2007
The optimization of design and operation of trigeneration plants for civil applications is a very complex task, because of the large number of internal and external variables affecting the energetic and economic results that may be achieved. Further, energy-saving and profit-oriented optimization processes usually lead to different solutions, in terms of plant lay-out, optimal size of components and operation strategy. Thermoeconomic methodologies are very effective theoretical structures for the optimization of industrial energy-systems characterised by regular energy-demand profiles; however, they are hard to use when approaching civil applications and energy systems in unsteady operating…
Selection of the Optimal Design Rainfall Return Period of Urban Drainage Systems
2014
Abstract The aim of this work is to define a methodology to identify the optimal rainfall return period for the design of urban drainage systems. The choice of the optimal return period is made minimizing the total costs of the system: the sewer network is dimensioned for a set of possible design rainfall return periods, and the corresponding construction, maintenance and operation costs are evaluated. For each scenario, the total expected damage from flooding caused by rainfall events with return period greater than the design one is then estimated by hydraulic simulation. This methodology has been applied to a small urban catchment in Palermo (Italy).
Bounds on transient phase plastic deformations in optimal design of steel frames subjected to cyclic loads
2009
A minimum volume multicriterion design of elastic perfectly plastic steel frames subjected to a combination of quasi-static fixed and cyclic loads, bounding the transient phase plastic deformations, is proposed. The problem is formulated according to a plastic shakedown criterion, so that incremental and instantaneous collapse are certainly prevented when the frame is subjected to very strongly amplified cyclic loads. The further condition that the structure must also behave elastically in serviceability conditions is imposed. Since the steady-state loading history is known it is possible to directly bound the steady-state plastic deformations. By applying a suitable own bounding theorem, i…