• Title/Summary/Keyword: optimizations

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A Rule-based Optimal Placement of Scaling Shifts in Floating-point to Fixed-point Conversion for a Fixed-point Processor

  • Park, Sang-Hyun;Cho, Doo-San;Kim, Tae-Song;Paek, Yun-Heung
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.6 no.4
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    • pp.234-239
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    • 2006
  • In the past decade, several tools have been developed to automate the floating-point to fixed-point conversion for DSP systems. In the conversion process, a number of scaling shifts are introduced, and they inevitably alter the original code sequence. Recently, we have observed that a compiler can often be adversely affected by this alteration, and consequently fails to generate efficient machine code for its target processor. In this paper, we present an optimization technique that safely migrates scaling shifts to other places within the code so that the compiler can produce better-quality code. We consider our technique to be safe in that it does not introduce new overflows, yet preserving the original SQNR. The experiments on a commercial fixed-point DSP processor exhibit that our technique is effective enough to achieve tangible improvement on code size and speed for a set of benchmarks.

Evaluating Join Performance on Relational Database Systems

  • Ordonez, Carlos;Garcia-Garcia, Javier
    • Journal of Computing Science and Engineering
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    • v.4 no.4
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    • pp.276-290
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    • 2010
  • The join operator is fundamental in relational database systems. Evaluating join queries on large tables is challenging because records need to be efficiently matched based on a given key. In this work, we analyze join queries in SQL with large tables in which a foreign key may be null, invalid or valid, given a referential integrity constraint. We conduct an extensive join performance evaluation on three DBMSs. Specifically, we study join queries varying table sizes, row size and key probabilistic distribution, inserting null, invalid or valid foreign key values. We also benchmark three well-known query optimizations: view materialization, secondary index and join reordering. Our experiments show certain optimizations perform well across DBMSs, whereas other optimizations depend on the DBMS architecture.

RELIABILITY-BASED OPTIMIZATION OF AIRFOILS USING A MOMENT METHOD AND PARSEC FUNCTION (모멘트 기법과 PARSEC 함수를 이용한 에어포일 신뢰성 기반 최적설계)

  • Lee, Jae-Hun;Kang, Hee-Youb;Kwon, Jang-Hyuk;Kwak, Byung-Man
    • 한국전산유체공학회:학술대회논문집
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    • 2010.05a
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    • pp.50-54
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    • 2010
  • In this study, reliability-based design optimizations of airfoils were performed. PARSEC function was used to consider the uncertainty of the aerodynamic shape for the reliability-based shape optimization of airfoils. Among aerodynamic performance. The accuracy of the reliability analysis was compared with other method and it was found that the moment method predicts the probability accurately. Deterministic and reliability-based optimizations were performed for shape of the RAE2822 airfoil and it was demonstrated that reliability-based optimizations the aerodynamic performances under uncertainties of the shape of the airfoil.

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Thermo-elastic Creep and Frequency Optimization by Using Feasible Direction Method (Feasible Direction Method를 사용한 열.탄성.크리프 및 진동수에 대한 최적화)

  • Jo, Hui-Geun;Park, Yeong-Won;Gang, Yeon-Sik;Lee, Gyeong-Don
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.25 no.5
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    • pp.857-865
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    • 2001
  • In finite element analysis, engineering optimizations are divided two major parts that are topology and structural optimization. Until these days most structural optimizations usually concentrate on single disciplinary optimization. Therefore numerical analysis and methodology which can optimize thermo-elastic creep and frequency phenomena are not suggested. In this paper finite element analysis methodology and algorithm of thermo -elastic creep and frequency optimizations are suggested and corroborate the efficiency of suggested new numerical methodology and algorithm by solving example problem.

Robust compensator design for parametric uncertain systems by separated optimizations (분리최적화 기법을 이용한 강인제어기 설계)

  • 김경수;박영진
    • 제어로봇시스템학회:학술대회논문집
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    • 1996.10b
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    • pp.589-592
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    • 1996
  • It is well known that robust compensators designed by the block-diagonal Lyapunov function approaches are conservative while they are popular in practice because of their computational easiness. In this note, we develop a systematized version of conventional block-diagonal Lyapunov function approaches by deriving two separated optimizations based on the guaranteed cost control method. The proposed method generates reasonable robust compensators in practice.

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Robust Constrained Predictive Control without On-line Optimizations

  • Lee, Y. I.;B. Kouvaritakis
    • 제어로봇시스템학회:학술대회논문집
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    • 2001.10a
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    • pp.27.4-27
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    • 2001
  • A stabilizing control method for linear systems with model uncertainties and hard input constraints is developed, which does not require on-line optimizations. This work is motivated by the constrained robust MPC(CRMPC) approach [3] which adopts the dual mode prediction strategy (i.e. free control moves and invariant set) and minimizes a worst case performance criterion. Based on the observation that, a feasible control sequence for a particular state can be found as a linear combination of feasible sequences for other states, we suggest a stabilizing control algorithm providing sub-optimal and feasible control sequences using pre-computed optimal sequences for some canonical states. The on-line computation of the proposed method reduces to simple matrix multiplication.

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Optimizations for Mobile MIMO Relay Molecular Communication via Diffusion with Network Coding

  • Cheng, Zhen;Sun, Jie;Yan, Jun;Tu, Yuchun
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.16 no.4
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    • pp.1373-1391
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    • 2022
  • We investigate mobile multiple-input multiple-output (MIMO) molecular communication via diffusion (MCvD) system which is consisted of two source nodes, two destination nodes and one relay node in the mobile three-dimensional channel. First, the combinations of decode-and-forward (DF) relaying protocol and network coding (NC) scheme are implemented at relay node. The adaptive thresholds at relay node and destination nodes can be obtained by maximum a posteriori (MAP) probability detection method. Then the mathematical expressions of the average bit error probability (BEP) of this mobile MIMO MCvD system based on DF and NC scheme are derived. Furthermore, in order to minimize the average BEP, we establish the optimization problem with optimization variables which include the ratio of the number of emitted molecules at two source nodes and the initial position of relay node. We put forward an iterative scheme based on block coordinate descent algorithm which can be used to solve the optimization problem and get optimal values of the optimization variables simultaneously. Finally, the numerical results reveal that the proposed iterative method has good convergence behavior. The average BEP performance of this system can be improved by performing the joint optimizations.

Automated optimization for memory-efficient high-performance deep neural network accelerators

  • Kim, HyunMi;Lyuh, Chun-Gi;Kwon, Youngsu
    • ETRI Journal
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    • v.42 no.4
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    • pp.505-517
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    • 2020
  • The increasing size and complexity of deep neural networks (DNNs) necessitate the development of efficient high-performance accelerators. An efficient memory structure and operating scheme provide an intuitive solution for high-performance accelerators along with dataflow control. Furthermore, the processing of various neural networks (NNs) requires a flexible memory architecture, programmable control scheme, and automated optimizations. We first propose an efficient architecture with flexibility while operating at a high frequency despite the large memory and PE-array sizes. We then improve the efficiency and usability of our architecture by automating the optimization algorithm. The experimental results show that the architecture increases the data reuse; a diagonal write path improves the performance by 1.44× on average across a wide range of NNs. The automated optimizations significantly enhance the performance from 3.8× to 14.79× and further provide usability. Therefore, automating the optimization as well as designing an efficient architecture is critical to realizing high-performance DNN accelerators.

Topology Optimization of Electromagnetic Systems with Nonlinear and Eddy Current Effects (비선형 및 Eddy Current효과를 고려한 전자기 시스템의 위상 최적 설계)

  • Kang, Je-Nam;Wang, Se-Myung
    • Proceedings of the KIEE Conference
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    • 2001.07b
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    • pp.768-770
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    • 2001
  • The topology optimizations of electromagnetic systems with the nonlinear and the eddy current effects are studied using the finite element method. The topology design sensitivity formulations of nonlinear magnetostatics and eddy current systems are derived using the adjoint variable method. A computer program is developed using object orient programming and applied to the topology optimization of a C-core actuator. A numerical study shows the effects of saturation and eddy current by comparing results of topology optimizations.

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