• Title/Summary/Keyword: geometric optimization

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Design Optimization of CML-Based High-Speed Digital Circuits (전류모드 논리 회로 기반의 고속 디지털 회로 디자인 최적화)

  • Jang, Ikchan;Kim, Jintae;Kim, SoYoung
    • Journal of the Institute of Electronics and Information Engineers
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    • v.51 no.11
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    • pp.57-65
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    • 2014
  • This paper presents a framework that is based on a reconfigurable macro-model of current-mode logic (CML) high-speed digital circuits enabling equation-based design optimization. The proposed macro-model is compatible with geometric programming, thereby enabling constraint-driven top-level power optimization. The proposed optimization framework is applied to a design of CML based serial-link transmitter with user-defined design specifications as an example of high speed digital circuits using 45nm and 90nm CMOS technology. The proposed optimization framework can derive a design with optimal power efficiency for given transistor technology nodes.

Optimization of modular Truss-Z by minimum-mass design under equivalent stress constraint

  • Zawidzki, Machi;Jankowski, Lukasz
    • Smart Structures and Systems
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    • v.21 no.6
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    • pp.715-725
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    • 2018
  • Truss-Z (TZ) is an Extremely Modular System (EMS). Such systems allow for creation of structurally sound free-form structures, are comprised of as few types of modules as possible, and are not constrained by a regular tessellation of space. Their objective is to create spatial structures in given environments connecting given terminals without self-intersections and obstacle-intersections. TZ is a skeletal modular system for creating free-form pedestrian ramps and ramp networks. The previous research on TZ focused on global discrete geometric optimization of the spatial configuration of modules. This paper reports on the first attempts at structural optimization of the module for a single-branch TZ. The internal topology and the sizing of module beams are subject to optimization. An important challenge is that the module is to be universal: it must be designed for the worst case scenario, as defined by the module position within a TZ branch and the geometric configuration of the branch itself. There are four variations of each module, and the number of unique TZ configurations grows exponentially with the branch length. The aim is to obtain minimum-mass modules with the von Mises equivalent stress constrained under certain design load. The resulting modules are further evaluated also in terms of the typical structural criterion of compliance.

A Robust Pricing/Lot-sizing Model and A Solution Method Based on Geometric Programming

  • Lim, Sung-Mook
    • Management Science and Financial Engineering
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    • v.14 no.2
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    • pp.13-23
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    • 2008
  • The pricing/lot-sizing problem of determining the robust optimal order quantity and selling price is discussed. The uncertainty of parameters characterized by an ellipsoid is explicitly incorporated into the problem. An approximation scheme is proposed to transform the problem into a geometric program, which can be efficiently and reliably solved using interior-point methods.

Two-Phase Approach to Optimal Weather Routing Using Real-Time Adaptive A* Algorithm and Geometric Programming (실시간 적응 A* 알고리즘과 기하학 프로그래밍을 이용한 선박 최적항로의 2단계 생성기법 연구)

  • Park, Jinmo;Kim, Nakwan
    • Journal of Ocean Engineering and Technology
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    • v.29 no.3
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    • pp.263-269
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    • 2015
  • This paper proposes a new approach for solving the weather routing problem by dividing it into two phases with the goal of fuel saving. The problem is to decide two optimal variables: the heading angle and speed of the ship under several constraints. In the first phase, the optimal route is obtained using the Real-Time Adaptive A* algorithm with a fixed ship speed. In other words, only the heading angle is decided. The second phase is the speed scheduling phase. In this phase, the original problem, which is a nonlinear optimization problem, is converted into a geometric programming problem. By solving this geometric programming problem, which is a convex optimization problem, we can obtain an optimal speed scheduling solution very efficiently. A simple case of numerical simulation is conducted in order to validate the proposed method, and the results show that the proposed method can save fuel compared to a constant engine output voyage and constant speed voyage.

The Optimized Design Method of Vehicle for Weight-Reduction (무게절감을 위한 차량 최적 설계 기법)

  • Lee, Jeong-Ick
    • Korean Journal of Computational Design and Engineering
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    • v.12 no.5
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    • pp.376-381
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    • 2007
  • The geometric configuration in the weight-reduced structure is very required to be started from the conceptual design with low cost, high performance and quality. In this point, a structural-topological shape concerned with conceptual design of structure is important. The method used in this paper combines three optimization techniques, where the shape and physical dimensions of the structure and material distribution are hierachically optimized, with the maximum rigidity of structure and lightweight.

Topology Optimization Using Digital Images (디지털 이미지를 이용한 위상최적설계)

  • Shin, Woon-Joo;Min, Seung-Jae
    • Korean Journal of Computational Design and Engineering
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    • v.11 no.4
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    • pp.265-272
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    • 2006
  • For the design and analysis of 3D object featuring complexity and irregularity in shape, sectional digital images measured by an industrial CT scanner are employed to generate a finite element model with uniform voxels. The voxel model plays a key role in developing an integrated reverse engineering system including geometric modeling, simulation and optimization. Design examples applied to topology optimization show that the proposed approach can provide a remarkable reduction in time cost at the conceptual and detail design stages.

Stability and PSR(Power-Supply Rejection) Models for Design Optimization of Capacitor-less LDO Regulators (회로 최적화를 위한 외부 커패시터가 없는 LDO 레귤레이터의 안정도와 PSR 성능 모델)

  • Joo, Soyeon;Kim, Jintae;Kim, SoYoung
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.26 no.1
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    • pp.71-80
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    • 2015
  • LDO(Low Drop-Out) regulators have become an essential building block in modern PMIC(Power Managment IC) to extend battery life of electronic devices. In this paper, we optimize capacitor-less LDO regulator via Geometric Programming(GP) designed using Dongbu HiTek $0.5{\mu}m$ BCDMOS process. GP-compatible models for stability and PSR of LDO regulators are derived based on monomial formulation of transistor characteristics. Average errors between simulation and the proposed model are 9.3 % and 13.1 %, for phase margin and PSR, respectively. Based on the proposed models, the capacitor-less LDO optimization can be performed by changing the PSR constraint of the design. The GP-compatible performance models developed in this work enables the design automation of capacitor-less LDO regulator for different design target specification.

Adaptation of Motion Capture Data of Human Arms to a Humanoid Robot Using Optimization

  • Kim, Chang-Hwan;Kim, Do-Ik
    • 제어로봇시스템학회:학술대회논문집
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    • 2005.06a
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    • pp.2126-2131
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    • 2005
  • Interactions of a humanoid with a human are important, when the humanoid is requested to provide people with human-friendly services in unknown or uncertain environment. Such interactions may require more complicated and human-like behaviors from the humanoid. In this work the arm motions of a human are discussed as the early stage of human motion imitation by a humanoid. A motion capture system is used to obtain human-friendly arm motions as references. However the captured motions may not be applied directly to the humanoid, since the differences in geometric or dynamics aspects as length, mass, degrees of freedom, and kinematics and dynamics capabilities exist between the humanoid and the human. To overcome this difficulty a method to adapt captured motions to a humanoid is developed. The geometric difference in the arm length is resolved by scaling the arm length of the humanoid with a constant. Using the scaled geometry of the humanoid the imitation of actor's arm motions is achieved by solving an inverse kinematics problem formulated using optimization. The errors between the captured trajectories of actor arms and the approximated trajectories of humanoid arms are minimized. Such dynamics capabilities of the joint motors as limits of joint position, velocity and acceleration are also imposed on the optimization problem. Two motions of one hand waiving and performing a statement in sign language are imitated by a humanoid through dynamics simulation.

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Parametric geometric model and shape optimization of an underwater glider with blended-wing-body

  • Sun, Chunya;Song, Baowei;Wang, Peng
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.7 no.6
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    • pp.995-1006
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    • 2015
  • Underwater glider, as a new kind of autonomous underwater vehicles, has many merits such as long-range, extended-duration and low costs. The shape of underwater glider is an important factor in determining the hydrodynamic efficiency. In this paper, a high lift to drag ratio configuration, the Blended-Wing-Body (BWB), is used to design a small civilian under water glider. In the parametric geometric model of the BWB underwater glider, the planform is defined with Bezier curve and linear line, and the section is defined with symmetrical airfoil NACA 0012. Computational investigations are carried out to study the hydrodynamic performance of the glider using the commercial Computational Fluid Dynamics (CFD) code Fluent. The Kriging-based genetic algorithm, called Efficient Global Optimization (EGO), is applied to hydrodynamic design optimization. The result demonstrates that the BWB underwater glider has excellent hydrodynamic performance, and the lift to drag ratio of initial design is increased by 7% in the EGO process.