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Design of Underactuated Steerable Electrode Arrays for Optimal Insertions

JOURNAL OF MECHANISMS AND ROBOTICS-TRANSACTIONS OF THE ASME 2013年第1期5卷 011008-011008页

作者： Zhang, Jian Simaan, Nabil Vanderbilt Univ Dept Mech Engn ARMA Lab Nashville TN 37235 USA

This paper addresses the design of wire actuated steerable electrode arrays for optimal insertions in cochlear implant surgery. These underactuated electrode arrays are treated as continuum robots which have an embedded actuation strand inside their flexible medium. By pulling on the actuation strand, an electrode array assumes a minimum-energy shape. The problems of designing optimal actuation strand placement are addressed in this paper. Based on the elastic modeling of the steerable electrode arrays proposed in this paper, an analytical solution of the strand placement is solved to minimize the shape discrepancy between a bent electrode array and a given target curve defined by the anatomy. Using the solved strand placement inside the steerable electrode array, an optimized insertion path planning with robotic assistance is proposed to execute the insertion process. Later, an optimization algorithm is presented to minimize the shape discrepancy between an inserted electrode array and a given target curve during the whole insertion process. Simulations show a steerable electrode array bending using the elastic model and robot insertion path planning with optimized strand placement. Two experiments have been conducted to validate the elastic model and algorithms. [DOI: 10.1115/1.4007005]

关键词： Modeling Shapes optimization algorithms Electrodes Robots

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Model Reduction Using Proper Orthogonal Decomposition and Predictive Control of Distributed Reactor System

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JOURNAL OF CONTROL SCIENCE AND ENGINEERING 2013年第unknown期2013卷 763165.1-763165.19页

作者： Marquez, Alejandro Espinosa Oviedo, Jairo Jose Odloak, Darci Univ Nacl Colombia Fac Minas Medellin 050041 Colombia Univ Sao Paulo Chem Engn Dept BR-05508900 Sao Paulo SP Brazil

This paper studies the application of proper orthogonal decomposition (POD) to reduce the order of distributed reactor models with axial and radial diffusion and the implementation of model predictive control (MPC) based on discrete-time linear time invariant (LTI) reduced-ordermodels. In this paper, the control objective is to keep the operation of the reactor at a desired operating condition in spite of the disturbances in the feed flow. This operating condition is determined by means of an optimization algorithm that provides the optimal temperature and concentration profiles for the system. Around these optimal profiles, the nonlinear partial differential equations (PDEs), that model the reactor are linearized, and afterwards the linear PDEs are discretized in space giving as a result a high-order linear model. POD and Galerkin projection are used to derive the low-order linear model that captures the dominant dynamics of the PDEs, which are subsequently used for controller design. An MPC formulation is constructed on the basis of the low-order linear model. The proposed approach is tested through simulation, and it is shown that the results are good with regard to keep the operation of the reactor.

关键词： low-order Reactors optimum temperature Maximum Allowable Concentration Pods linear models Orthogonal Predictive control REACTOR OPERATION optimization algorithms Surgery Reduced order model Model predictive control

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Automatic Detection of 2D and 3D Lung Nodules in Chest Spiral CT Scans

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INTERNATIONAL JOURNAL OF BIOMEDICAL IMAGING 2013年第1期2013卷 517632页

作者： El-Baz, Ayman Elnakib, Ahmed Abou El-Ghar, Mohamed Gimel'farb, Georgy Falk, Robert Farag, Aly Univ Louisville Dept Bioengn Bioimaging Lab Louisville KY 40292 USA Univ Mansoura Urol & Nephrol Dept Mansoura 35516 Egypt Univ Auckland Dept Comp Sci Auckland 1142 New Zealand Jewish Hosp Med Imaging Div Louisville KY 40202 USA Univ Louisville Elect & Comp Engn Dept Louisville KY 40292 USA

Automatic detection of lung nodules is an important problem in computer analysis of chest radiographs. In this paper, we propose a novel algorithm for isolating lung abnormalities (nodules) from spiral chest low-dose CT (LDCT) scans. The proposed algorithm consists of three main steps. The first step isolates the lung nodules, arteries, veins, bronchi, and bronchioles from the surrounding anatomical structures. The second step detects lung nodules using deformable 3D and 2D templates describing typical geometry and gray-level distribution within the nodules of the same type. The detection combines the normalized cross-correlation template matching and a genetic optimization algorithm. The final step eliminates the false positive nodules (FPNs) using three features that robustly define the true lung nodules. Experiments with 200 CT data sets show that the proposed approach provided comparable results with respect to the experts.

关键词： Computer aided analysis Dataset gray level distribution Lung nodules Spiral Computed Tomography optimization algorithms automatic detection Bronchioles

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ADAPTIVE PROBABILISTIC BRANCH AND BOUND WITH CONFIDENCE INTERVALS FOR LEVEL SET APPROXIMATION 13

ADAPTIVE PROBABILISTIC BRANCH AND BOUND WITH CONFIDENCE INTE...

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Winter Simulation Conference on Simulation - Making Decisions in a Complex World

作者： Huang, Hao Zabinsky, Zelda B. Univ Washington Seattle WA 98195 USA

ISBN: (纸本)9781479939503;9781479920778

We present a simulation optimization algorithm called probabilistic branch and bound with confidence intervals (PBnB with CI), which is designed to approximate a level set of solutions for a user-defined quantile. PBnB with CI is developed for both deterministic and noisy problems with mixed continuous and discrete variables. The quality of the results is statistically analyzed with order statistic techniques and confidence intervals are derived. Also, the number of samples and replications are designed to achieve a certain quality of solutions. When the algorithm terminates, it provides an estimation of the desired quantile with confidence intervals, and an approximation level set, including a statistically guaranteed set in the true desirable level set, a statistically pruned set, and a set which is not statistically specified. We also present numerical experiments with benchmark functions to visualize the algorithm and its capability.

关键词： Confidence intervals approximation optimization algorithms branches Level set Chlorine Solutions Quantile BENCHMARKS

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Optimum Path Synthesis of a Geared Five-Bar Mechanism

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ADVANCES IN MECHANICAL ENGINEERING 2013年第Pt.1期5卷 757935-1-757935-13页

作者： Lin, Wen-Yi De Lin Inst Technol Dept Mech Engn New Taipei City 23654 Taiwan

Most studies on path synthesis problems are to trace simple or smooth trajectories. In this work, an optimum synthesis for several special trajectories generated by a geared five-bar mechanism is studied using the one-phase synthesis method. The synthesis problem for the special trajectories, which is originally studied using the two-phase synthesis method discussed in the literature, is a real challenge due to very few dimensionally proportioned mechanisms that can generate the special trajectories. The challenging special trajectories with up to 41 discrete points include a self-overlapping curve, nonsmooth curves with straight segments and vertices, and sophisticated shapes. The error function of the square deviation of positions is used as the objective function and the GA-DE evolutionary algorithm is used to solve the optimization problems. Findings show that the proposed method can obtain approximately matched trajectories at the cost of a tremendous number of evaluations of the objective function. Therefore, the challenging problems may serve as the benchmark problems to test the effectiveness and efficiency of synthesis methods and/or optimization algorithms. All the synthesized solutions have been validated using the animation of the SolidWorks assembly so that the obtained mechanisms are sound and usable.

关键词： Benchmark testing optimization algorithms trajectory ERROR FUNCTIONS Objective function Solid-Phase Synthesis Techniques synthesis optimal path Animation evolutionary algorithm

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A modified particle swarm approach for multi-objective optimization of laminated composite structures

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STRUCTURAL ENGINEERING AND MECHANICS 2012年第3期42卷 335-352页

作者： Sepehri, A. Daneshmand, F. Jafarpur, K. Shiraz Univ Sch Mech Engn Shiraz Iran McGill Univ Dept Mech Engn Montreal PQ H3A 2K6 Canada

Particle Swarm optimization (PSO) is a stochastic population based optimization algorithm which has attracted attentions of many researchers. This method has great potentials to be applied to many optimization problems. Despite its robustness the standard version of PSO has some drawbacks that may reduce its performance in optimization of complex structures such as laminated composites. In this paper by suggesting a new variation scheme for acceleration parameters and inertial weight factors of PSO a novel optimization algorithm is developed to enhance the basic version's performance in optimization of laminated composite structures. To verify the performance of the new proposed method, it is applied in two multi-objective design optimization problems of laminated cylindrical. The numerical results from the proposed method are compared with those from two other conventional versions of PSO-based algorithms. The convergancy of the new algorithms is also compared with the other two versions. The results reveal that the new modifications in the basic forms of particle swarm optimization method can increase its convergence speed and evade it from local optima traps. It is shown that the parameter variation scheme as presented in this paper is successful and can evenfind more preferable optimum results in design of laminated composite structures.

关键词： cylindrical composite laminated shell optimization algorithms particle swarm optimization

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Automated Multitrajectory Method for Reaction optimization in a Microfluidic System using Online IR Analysis

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ORGANIC PROCESS RESEARCH & DEVELOPMENT 2012年第8期16卷 1409-1415页

作者： Moore, Jason S. Jensen, Klavs F. Dept Chem Engn Novartis MIT Ctr Continuous Mfg Ma Cambridge MA 02139 USA

An automated multitrajectory optimization platform with continuous online infrared (IR) monitoring is presented. The production rate of a Paal-Knorr reaction is maximized within a constrained temperature and residence time design space. The automated platform utilizes a microreactor system to carry out optimizations with low material requirements and implements a micro IR flow cell for continuous online monitoring of reaction conversion. The approach to steady state at each set of reaction conditions is assessed continuously before the objective function is evaluated and reactor conditions move to the next set point. Several optimization algorithms are tested for their performance on a complex objective terrain. Each function comes to agreement on the optimal conditions but requires a significantly different number of experiments to reach the final conditions. Additionally, multiple objective functions are compared to analyze the trade-off between production rate and conversion.

关键词： on line detection Automation Objective function iridium reaction optimization Natural Increase Microfluidics Conversion Disorder optimization algorithms Set of points

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Design and optimization of Future Hybrid and Electric Propulsion Systems: An Advanced Tool Integrated in a Complete Workflow to Study Electric Devices

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OIL & GAS SCIENCE AND TECHNOLOGY-REVUE D IFP ENERGIES NOUVELLES 2012年第4期67卷 547-562页

作者： Le Berr, F. Abdelli, A. Postariu, D. -M. Benlamine, R. IFP Energies Nouvelles F-92852 Rueil Malmaison France

Design and optimization of Future Hybrid and Electric Propulsion Systems: An Advanced Tool Integrated in a Complete Workflow to Study Electric Devices - Electrification to reduce greenhouse effect gases in transport sector is now well-known as a relevant and future solution studied intensively by the whole actors of the domain. To reach this objective, a tool for design and characterization of electric machines has been developed at IFP Energies nouvelles. This tool, called EMTool, is based on physical equations and is integrated to a complete workflow of simulation tools, as Finite Element Models or System Simulation. This tool offers the possibility to study several types of electric machine topologies: permanent magnet synchronous machine with radial or axial flux, induction machines, etc. This paper presents the main principles of design and the main equations integrated in the EMTool, the methods to evaluate electric machine performances and the validations performed on existing machine. Finally, the position of the EMTool in the simulation tool workflow and application examples are presented, notably by coupling the EMTool with advanced optimization algorithms or finite element models.

关键词： simulation tool design theory finite element model Integrate electric machines machine performance Permanent magnet synchronous machines systems simulation optimization algorithms ELECTRIC PROPULSION Electric devices Greenhouse gases

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Intelligent OLSR Routing Protocol optimization for VANETs

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2012年第4期61卷 1884-1894页

作者： Toutouh, Jamal Garcia-Nieto, Jose Alba, Enrique Univ Malaga Dept Lenguajes & Ciencias Comp E-29071 Malaga Spain

Recent advances in wireless technologies have given rise to the emergence of vehicular ad hoc networks (VANETs). In such networks, the limited coverage of WiFi and the high mobility of the nodes generate frequent topology changes and network fragmentations. For these reasons, and taking into account that there is no central manager entity, routing packets through the network is a challenging task. Therefore, offering an efficient routing strategy is crucial to the deployment of VANETs. This paper deals with the optimal parameter setting of the optimized link state routing (OLSR), which is a well-known mobile ad hoc network routing protocol, by defining an optimization problem. This way, a series of representative metaheuristic algorithms (particle swarm optimization, differential evolution, genetic algorithm, and simulated annealing) are studied in this paper to find automatically optimal configurations of this routing protocol. In addition, a set of realistic VANET scenarios (based in the city of Malaga) have been defined to accurately evaluate the performance of the network under our automatic OLSR. In the experiments, our tuned OLSR configurations result in better quality of service (QoS) than the standard request for comments (RFC 3626), as well as several human experts, making it amenable for utilization in VANET configurations.

关键词： Metaheuristics optimization algorithms optimized link state routing (OLSR) vehicular ad hoc networks (VANET)

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Vibration analysis and design optimization of viscoelastic sandwich cylindrical shell

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JOURNAL OF SOUND AND VIBRATION 2012年第12期331卷 2729-2752页

作者： Mohammadi, Farough Sedaghati, Ramin Concordia Univ Dept Mech & Ind Engn Montreal PQ H3G 1M8 Canada

Damping properties of viscoelastic sandwich structure can be improved by changing some parameters such as thickness of the layers, distribution of partial treatments, slippage between layers at the interfaces, cutting and its distribution at the top and core layers. Since the optimization problem may result in a thick core layer, for achieving more accuracy a new higher-order Taylor's expansion of transverse and in-plane displacement fields is developed for the core layer of sandwich cylindrical shell in which the displacement fields at the core layer are compatibly described in terms of the displacement fields at the elastic faces. The presented model includes fewer parameters than the previously developed models and therefore decreases the number of degree of freedom in the finite element modeling. The transverse normal stress in the core layer is also considered. The formulations are developed to consider the slippage between layers at the interfaces. Finally, by combining the finite element method and the optimization algorithms based on the genetic algorithm and sequential quadratic programming technique, a design optimization methodology has been formulated to maximize the damping characteristics using the optimal number and location of cuts and partial treatments with optimal thicknesses of top and core layers. (C) 2012 Elsevier Ltd. All rights reserved.

关键词： optimization algorithms Vibration analysis Damping capacity Transverse CORE LAYER Finite element method Cylindrical Interfaces Optimal design Interface

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