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Small Rotor Design optimization Using Blade Element Momentum Theory and Hover Tests

JOURNAL OF AIRCRAFT 2010年第1期47卷 268-283页

作者： Bohorquez, Felipe Pines, Darryll Samuel, Paul D. Univ Maryland Dept Aerosp Engn Smart Struct Lab Alfred Gessow Rotorcraft Ctr College Pk MD 20742 USA

The current investigation focuses on the development of a low-cost computational methodology to design and optimize hovering rotors for small-scale vehicles using circular arc airfoils. Rotors for vehicles having a representative Re between 5000 and 60,000 were considered. A detailed experimental study of rectangular and tapered blades generated the data necessary to identify main performance trends and the effect of planform modifications. A blade element momentum theory model coupled with a table lookup scheme was implemented. The database was interpolated along three dimensions (Re, camber, and angle of attack) to obtain the local aerodynamic coefficients used in the calculation of the nonlinear inflow distribution along the blade span. Two methodologies were used in the calculation of the database. First, a purely numerical approach using the two-dimensional flow solver INS2D was evaluated. Second, a reverse method that used the experimental rotor data to refine the original previously generated database was investigated. Validation showed that the model predictive capabilities improved with the empirical corrections. An optimization algorithm was implemented to perform a grid search using power loading as the hover efficiency metric. The methodology proposed is able to optimize blade geometry and operating conditions following imposed constraints within a defined design space.

关键词： Blade Element Momentum Theory Aerodynamic Performance Aerodynamic Characteristics Airfoil Databases CFD Simulation Micro Air Vehicle optimization algorithm Vortex Modeling Air Vehicle Computational Methods

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A Tool for Photovoltaic Panels Modeling and Testing

A Tool for Photovoltaic Panels Modeling and Testing

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International Instrumentation and Measurement Technology Conference (I2MTC)

作者： Adamo, F. Attivissimo, F. Spadavecchia, M. DEE Polytech Bari Elect & Elect Measurements Lab Bari Italy

ISBN: (纸本)9781424428335

This paper presents the results obtained testing a tool designed to characterize and simulate the behavior of a Photovoltaic (PV) panel under real and/or simulated working conditions. The presented tool permits the continuous monitoring of the I-V (Current-Voltage) and P-V (Power-Voltage) characteristics of the panel and the comparison between actual and expected performance;in this way it is possible to prevent any possible decrease of the output power and to replace the monitored module before it goes out of order or its efficiency falls under a given threshold. The well known two-diode model is used to estimate the parameters of the electrical equivalent circuit of the PV panel and to simulate both the I-V and P-V characteristic curves in any given environmental condition of irradiation and/or temperature. The model and the estimation algorithm are implemented as a MATLAB (R) script while the user interface is designed with LabVIEW (TM). The presented tool has been validated against an experimentally characterized PV panel. The environmental parameters of the model such as irradiance and temperature have been measured directly, whereas the others parameters have been evaluated using a best-fit algorithm on the measured data.

关键词： component Photovoltaic panel mathematical model simulation Newton's method optimization algorithm characterization

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Computational optimization, modelling and simulation–a paradigm shift

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Procedia Computer Science 2010年第1期1卷 1297-1300页

作者： Xin-She Yang Slawomir Koziel Department of Engineering University of Cambridge Trumpington Street Cambridge CB2 1PZ UK Engineering Optimization and Modeling Center School of Science and Engineering Reykjavik University 101 Reykjavik Iceland

Computational optimization forms an integrated part of modern computational science. Any good design should intend to achieve certain optimality, though optimal solutions are often difficult to find in practice since uncertainty and nonlinearity always present in almost all real-world problems. As resources, time and money are always limited, optimization becomes even more important in practice. This workshop on Computational optimization, Modelling and Simulation (COMS 2010) at ICCS 2010 will summarize the latest developments of optimization and modelling and their applications in science, engineering and industry

关键词： algorithm Black-box modelling Computational optimization Derivative-free method optimization algorithm Modelling Nonlinear optimization Surragate-based optimization Simulation

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Band-gap engineering in CIGS solar cells using Nelder-Mead simplex optimization algorithm

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THIN SOLID FILMS 2006年 511卷 60-65页

作者： Cernivec, G. Krc, J. Smole, F. Topic, M. Univ Ljubljana Fac Elect Engn Ljubljana 1000 Slovenia

Band-gap grading in a CIGS absorber and a conduction band offset at n/p hetero-interface are two important parameters of band-gap engineering aiming at high efficient CIGS solar cells. To obtain optimal CIGS absorber's band-gap grading profile an automatic optimization loop based on Nelder-Mead simplex optimization algorithm has been implemented. The optimization problem is described with an objective function, which-by varying the input parameters-is minimized or maximized. In our study two types of objective functions are used;optical and electrical. As the most optimal profile a parabolic, double graded band-gap profile with a positive or nearly zero conduction band offset at n/p hetero-interface is calculated. Structures with different CIGS absorber thicknesses and bulk and/or hetero-interface recombination lifetimes are examined and their optimized parameters are discussed in the light of experimental achievements. (c) 2005 Elsevier B.V All rights reserved.

关键词： CIGS solar cell graded absorber window/absorber hetero-interface optimization algorithm

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A new quantization optimization algorithm for the MPEG advanced audio coder using a statistical subband model of the quantization noise

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IEEE TRANSACTIONS ON AUDIO SPEECH AND LANGUAGE PROCESSING 2006年第4期14卷 1328-1339页

作者： Derrien, O Duhamel, P Charbit, M Richard, G ENST TSI Signal & Image Proc Dept F-75634 Paris 13 France Ecole Super Elect LSS CNRS Signals & Syst Lab F-91192 Gif Sur Yvette France

In this paper, an improvement of the quantization optimization algorithm for the MPEG-Advanced Audio Coder (AAC) is presented. This algorithm, given a bit-rate constraint, minimizes the perceived distortion generated by the signal compression. The distortion can be related to the quantization error level over frequency subbands through an auditory model. Thus, optimizing the quantization requires knowledge of the rate-distortion function for each subband. When this function can be modeled in a simple way, the algorithm can take a one-loop recursive structure. However, in the MPEG AAC, the rate-distortion function is hard to characterize, since AAC makes use of nonlinear quantizers and variable length entropy coders. As a result, the standard algorithm makes use of two nested loops with a local decoder, in order to measure the error level rather than predicting its value. We first describe a partial subband modeling of the rate-distortion function of interest in the MPEG AAC. Then, using a statistical approach, we find a relationship between the error level and the so-called quantization "scale-factor" and propose a new algorithm that is basically similar to a classical one loop "bit allocation" process. Finally, we describe the complete algorithm and show that it is more efficient than the standard one.

关键词： bit-rate constraint distortion constraint optimization algorithm perceptual audio coding scale-factor statistical model subband quantization

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An orthogonal array based optimization algorithm for computer-aided measurement of worm surface

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INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY 2006年第5-6期30卷 434-443页

作者： Mohan, L. V. Shunmugam, M. S. Indian Inst Technol Dept Mech Engn Mfg Engn Sect Madras 600036 Tamil Nadu India

Being versatile and fast, a co-ordinate measuring machine is used for the measurement of worm. A best-fit surface is obtained from the measured points by a surface fitting method, which minimizes the root mean square of normal deviations. For this problem in discrete space, an iterative optimization algorithm based on an orthogonal array is developed. On minimizing the objective function, the deviations of worm parameters from the specified values are obtained. The algorithm is validated using input data points generated from a straight-sided in axial section worm (ZA worm) with known errors. The proposed algorithm requires fewer objective function evaluations and the result is highly repeatable as there are no random operations involved.

关键词： worm measurement optimization algorithm orthogonal array

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PASCAL: A Protocol-based Approach for Service Composition and Dependable optimization

PASCAL: A Protocol-based Approach for Service Composition an...

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The Fifth IEEE International Symposium on Service-Oriented System Engineering(第五届IEEE面向服务的系统工程国际研讨会 SOSE 2010)

作者： Huipeng Guo Jianxin Li Zongxia Du Xudong Liu Mu Li School of Economics and ManagementBeihang University Beijing P. R. China School of Computer Science and EngineeringBeihang University Beijing P. R. China School of Computer Science and Engineering Beihang University Beijing P. R. China

Service composition is a promising technique for developing applications especially for those across multiple organizations. The dependability of composite services, however, is difficult to be guaranteed due to the distributed, dynamic and autonomous characteristics of service domains. In this paper, we address this problem by proposing a novel approach—PASCAL (Protocol-based Approach for Web Service Composition And DependabLe optimization). We initially propose a protocol based service composition system architecture supporting online monitoring of services interaction and dynamic replacing of service. Then, we design the dependable optimization mechanism based on the service and dependencies monitoring. Furthermore, we design an algorithm to adjust the configuration adaptively base on policies and protocols to keep the composite service dependable while service failure appears. Finally we implement the PASCAL approach based on XService suit and evaluate the proposed mechanism through comprehensive experiments and achieve improved results.

关键词： service composition protocol composition service dependency optimization algorithm failure diagnosis

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Study on modeling of multispectral emissivity and optimization algorithm

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IEEE TRANSACTIONS ON NEURAL NETWORKS 2006年第1期17卷 238-242页

作者： Yang, CL Yu, Y Zhao, DY Zhao, GL Harbin Inst Technol Dept Elect Engn Harbin 150001 Heilongjiang Peoples R China Harbin Engn Univ Dept Automat Harbin 150001 Heilongjiang Peoples R China

Target's spectral emissivity changes variously, and how to obtain target's continuous spectral emissivity is a difficult problem to be well solved nowadays. In this letter, an activation-function-tunable neural network is established, and a multistep searching method which can be used to train the model is proposed. The proposed method can effectively calculate the object's continuous spectral emissivity from the multispectral radiation information. It is a universal method, which can be used to realize on-line emissivity demarcation.

关键词： neural networks optimization algorithm spectral emissivity tunable activation function

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Research on Intelligence Decision-making Analysis and optimization Design Development of Pavement Management System

Research on Intelligence Decision-making Analysis and Optimi...

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2010 The 3rd International Conference on Computational Intelligence and Industrial Application (PACIIA2010)

作者： DAI Xue-zhen, XING Lei and ZHANG Bo Key Laboratory for Special Area Highway Engineering of Ministry of Education, Chang’an University Xi’an Shaanxi 710064, China

The present research, based on system engineering, information engineering technology, applied mathematics, and the theories and methodology of safety predicative assessment, carried out a thorough and in-depth research into the intelligence decision-making and analysis for optimization design development of road surface maintenance system from the aspects of data support, road performance assessment and optimization and selection scheme for maintenance decision-making and strategies. In addition, the optimization algorithm is provided for data categorization and sifting as well as the division of storage units. Then, an optimization model is constructed based on the load bearing capacity of road structures, road quality for driving, road safety for driving together with road surface damage. At last, based on multi-model predications and the correlation analysis for predicative concepts of decision-making flow for road surface performance, the PPM optimization model is constructed for protective maintenance modules for road surface and the mathematical model and method are offered for the optimization and selection of strategic schemes.

关键词： Pavement Management System Model optimization optimization algorithm Strategy optimization and Selection

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Bodies Having Minimum Pressure Drag in Supersonic Flow: Investigating Nonlinear Effects

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JOURNAL OF AIRCRAFT 2010年第4期47卷 1451-1454页

作者： Palaniappan, Karthik Jameson, Antony Stanford Univ Dept Aeronaut & Astronaut Stanford CA 94305 USA

Nonlinear effects on bodies having minimum pressure drag in supersonic flow were reported. The minimum pressure drag problem was set up and solved using a nonlinear flowmodel. optimization was carried out using the adjoint method. In both the two-dimensional case and the axisymmetric case, the resulting optimum profiles were compared with the optimum profiles obtained from linear theory. The main assumptions of linear theory are that the flow is isentropic, irrotational, and the perturbation velocities in the axial and normal directions are very small compared with the freestream velocity. These assumptions are valid everywhere except in the vicinity of the leading and the trailing edges, where there are stagnation points. There is no Mach number dependence for axisymmetric flow. The optimal shapes become closer to their linear theory counterparts at low Mach numbers and small fineness ratios. The main conclusion that is made is that the results from linear theory are very good as far as the optimum drag shapes are concerned.

关键词： Aerodynamic Shape optimization Two Dimensional Flow optimization algorithm Supersonic Flight Pressure Coefficient Computational Fluid Dynamics Flow Equations Astronautics Aeronautics

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