Multi-objective Design Procedure Research Articles

Numerical and experimental investigation of erosive wear in Francis runner blade optimized for sediment laden hydropower projects in Nepal

The design of the Francis turbine aims to maximize its performance in terms of efficiency. This design approach has overlooked effects on the turbine due to sediment erosion for power plants operating under high sediment load. In this paper, a multi-objective design procedure to develop a Francis turbine runner for maximizing efficiency, as well as minimizing sediment erosion is discussed. Parameterized runner designs obtained from the design algorithm are implemented in the Design of Experiment (DOE) to get sample runners. These sample runners are investigated using a commercial CFD tool and validating with an experiment in a model turbine test rig to obtain efficiency and sediment erosion data. Subsequently, a Multi-Objective Genetic Algorithm (MOGA) is implemented to generate the optimized runner blades. Two different optimized runners are selected after the optimization. The optimized runner generated from this technique is further investigated experimentally in the laboratory scale sediment erosion test rig. From both numerical and experimental results, it is found that the optimized runner blade has improved erosion handling capability. Implementation of the procedure discussed in this article can be a crucial step for designing the turbines which are vulnerable to sediment erosion.

Single reflector design for integrated low/high beam meeting multiple regulations with light field management.

This paper proposed an effective multi-objective design procedure, called light field management, for a single multi-segment reflector that can simultaneously project low beams and high beams for bicycle and e-bike applications. Furthermore, two different regulations can be met, including the K-mark and the ECE Class B regulations. Through light field management, the etendue and flux density of each segment can be effectively managed, so that the design successfully meets the multiple regulations. In the experimental verification, two mockup samples including a plastic reflector with aluminum coating and an aluminum reflector were fabricated to verify the validity of the design. The experiment showed that the contrast across the cutoff line reached 100 and above, where the brightest point for low beams reached 200 lux and the whole pattern reached 250 lux. The supreme behavior of the head lamp shows that the proposed design procedure is valuable and helpful to an optical designer.

Review on the state‐of‐the‐art multi‐objective optimisation of hybrid standalone/grid‐connected energy systems

Integration of renewable and energy storage components in standalone/grid-connected energy systems, which results in hybrid energy systems, is increasing nowadays. Optimisation of hybrid energy systems is an essential matter for economic, clean, convenient and reliable energy supply. Since the optimal design should satisfy multiple objectives, application of multi-objective optimisation is preferred rather than a single-objective solution. By multi-objective optimisation, a trade-off among different objectives can be obtained. This study presents a timely survey on the state-of-the-art in multi-objective optimal design of hybrid standalone/grid-connected energy systems. The existing literature is categorised by various indices: (i) standalone or grid-connected mode; (ii) number and type of objective functions; (iii) completely renewable-based or diesel-renewable-based hybrid systems; and (iv) multi-energy systems. The applied objective functions, design constraints and decision variables in the optimisation of hybrid energy systems are addressed. It is found that the recent objective functions like customer satisfaction and grid-dependency need further investigation in the multi-objective design procedure.

Multi-Objective Design of Antennas Using Variable-Fidelity Simulations and Surrogate Models

A computationally-efficient procedure for multi-objective design of antenna structures is presented. Our approach exploits the multi-objective evolutionary algorithm (MOEA) working with a fast antenna surrogate model obtained with kriging interpolation of coarse-discretization simulation data. Response correction techniques are subsequently applied to refine the designs obtained by MOEA. Our methodology allows us to obtain-at a low computational cost-a set of designs corresponding to various trade-offs between the antenna size and the refection coefficient. Two illustration examples are considered: (i) an UWB monocone with two objectives being reduction of the antenna size and minimization of the antenna reflection coefficient in the bandwidth of interest, and (ii) a planar Yagi antenna with the objectives being an increase of the end-fire gain and minimization of the reflection coefficient, both in the bandwidth of interest.

Multiobjective Optimization of Ultraflat Magnetic Components With PCB-Integrated Core

In future applications, e.g., in ultra-flat OLED lamp drivers or flat screen power supplies, ultra-flat ac/dc and dc/dc converter systems are highly demanded. Therefore, the design and implementation of a printed circuit board (PCB)-integrated flyback transformer for a 1-mm-thin single-phase power factor correction rectifier is under investigation. In this paper, first an overview on several integration methods is given. It is shown that the PCB integration of magnetic cores allows us to achieve the required thickness of 1 mm and a high energy density. In a next step, the design and the realization of ultra-flat magnetic components with PCB-integrated cores are discussed in detail. The presented multi-objective design procedure determines the inductor and/or transformer setup optimal with respect to minimal losses and/or minimal footprint area; for this purpose, all required electrical, magnetic, and geometrical parameters of the magnetic component are considered in the design process. Furthermore, all specific implications entailed by the PCB-integrated core, e.g., the core setup, anisotropic core losses, the interleaving of windings, or an accurate reluctance model are treated. Finally, experimental results are used to verify the design procedure.

Memetic optimization algorithm applied to design microwave amplifier for the specific gain value constrained by the minimum noise over the available bandwidth

In this work, the neural performance and fuzzy logic data sheets of the transistor are used to determine the feasible design target space in the optimization of a microwave amplifier. The compatible (Noise F, Input VSWR Vi, Gain GT) triplets and their (ZS, ZL) terminations of a microwave transistor are exploited for an amplifier design with the minimum noise Fmin(f), required gain GTreq(f), and a low input VSWR Vi over the available bandwidth. The multi-objective design procedure is obtained from ZS(f), ZL(f) terminations with the unit-elements and short-circuited stubs in the L+L configurations and memetic optimization algorithm is successfully implemented as an optimization tool. A typical design example is given with its challenging performance in the simple L+L configurations realizable by the microstrip line technology. © 2010 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2010.

DESIGN OF AN ULTRA-WIDEBAND, LOW-NOISE AMPLIFIER USING A SINGLE TRANSISTOR: A TYPICAL APPLICATION EXAMPLE

In this work, a design method of an Ultra-Wideband (UWB), low-noise amplifler (LNA) is proposed exerting the perfor- mance limitations of a single high-quality discrete transistor. For this purpose, the compatible (Noise F, Input VSWR Vi, Gain GT) triplets and their (ZS, ZL) terminations of a microwave transistor are exploited for the feasible design target space with the minimum noise Fmin(f), maximum gain GT max(f) and a low input VSWR Vi over the available bandwidth B. This multi-objective design procedure is reduced into syntheses of the Darlington equivalences of the ZSopt(f), ZLmax(f) terminations with the Unit-elements and short-circuited stubs in the T-, L-, ƒ-conflgurations and Particle Swarm Intelligence is successfully implemented as a comparatively simple and e-cient optimization tool into both veriflcation of the design target space and the design process of the input and output matching circuits. A typical design exam- ple is given with its challenging performance in the simple ƒ- and ƒ-conflgurations realizable by the microstrip line technology. Further- more the performances of the synthesized ampliflers are compared us- ing an analysis programme in MATLAB code and a microwave system simulator and verifled to agree with each other.

Design of virtual manufacturing cells: a mathematical programming approach

In this paper, a new type of virtual cellular manufacturing (CM) system is considered, and a multi-objective design procedure is developed for designing such cells in real time. Retaining the functional layout, virtual cells are addressed as temporary groupings of machines, jobs and workers to realize the benefits of CM. The virtual cells are created periodically, for instance every week or every month, depending on changes in demand volumes and mix, as new jobs accumulate during a planning period. The procedure includes labor grouping considerations in addition to part-machine grouping. The procedure is based on interactive goal programming methods. Factors such as capacity constraints, cell size restrictions, minimization of load imbalances, minimization of inter-cell movements of parts, provision of flexibility, etc. are considered. In labor grouping, the functionally specialized labor pools are partitioned and regrouped into virtual cells. Factors such as ensuring balanced loads for workers, minimization of inter-cell movements of workers, providing adequate levels of labor flexibility, etc. are considered in a pragmatic manner.