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Designing Cyclic Schedules for Streaming Repetitive Job-Shop Manufacturing Systems with Blocking and No-Wait Constraints

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IFAC-PapersOnLine 2019年第10期52卷 73-78页

作者： R. Wójcik J. Pempera Department of Computer Engineering Faculty of Electronics Wrocław University of Science and Technology Wrocław Poland Department of Control Systems and Mechatronics Faculty of Electronics Wrocław University of Science and Technology Wrocław Poland

We consider a problem of designing no-wait cyclic schedules for job-shop manufacturing system with repetitive transportation tasks that are defined by sequences of operations. Each operation is performed in a sector of manufacturing system using its resources, e.g. vehicles, machines, and takes some time for manufacturing and transportation. The sectors and their resources can be shared by several tasks in the exclusive mode. There are no buffers between sectors thus when a transportation car is in a sector it blocks this sector to other cars and cannot leave it until a sector which is required by the following operation in its transportation route is free. The repetitive transportation tasks performed in a manufacturing system are modelled as a system of cyclic processes executing sequences of operations and sharing common resources according to a mutual exclusion protocol. The problem consists in finding no-wait cyclic schedules for which no process (tasks) that started execution will wait for resources (sectors) required to execute its operations and each operation will be started immediately after finishing the previous one. The casade-like structure (C-LS) system of processes is considered. This system is structurally deadlock-free therefore no-buffer (resource blocking) constraint will never lead to deadlock state. The C-LS system of processes can be seen as a composition of subsystems with two cyclic processes sharing a single resource, namely 2-P subsystems. Using our recurrent integer modulus equations model (developed in our previous works) we find for each 2-P subsystem all possible start times of the processes (if exist) that belong to a no-wait schedule and construct all possible no-wait schedules for each component 2-P. Finally, we design cyclic no-wait schedules for the C-LS system by joining the cyclic schedules designed for its component 2-P subsystems.

关键词： Repetitive tasks cyclic processes job-shop systems blocking no-wait constraints cyclic scheduling two processes sharing resource cascade-like structured systems cyclic schedules integration

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Fundamental issues regarding uncertainties in artificial neural networks

arXiv

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arXiv 2020年

作者： Thacker, N.A. Twining, C.J. Tar, P.D. Notley, S. Ramesh, V. Division of Informatics Imaging & Data Sciences University of Manchester United Kingdom Department of Computer Science University of Manchester United Kingdom Department of Automatic Control and Systems Engineering University of Sheffield United Kingdom Center for Cognition and Computation Goethe-Universität Frankfurt am Main Germany

Artificial Neural Networks (ANNs) implement a specific form of multi-variate extrapolation and will generate an output for any input pattern, even when there is no similar training pattern. Extrapolations are not necessarily to be trusted, and in order to support safety critical systems, we require such systems to give an indication of the training sample related uncertainty associated with their output. Some readers may think that this is a well known issue which is already covered by the basic principles of pattern recognition. We will explain below how this is not the case and how the conventional (Likelihood estimate of) conditional probability of classification does not correctly assess this uncertainty. We provide a discussion of the standard interpretations of this problem and show how a quantitative approach based upon long standing methods can be practically applied. The methods are illustrated on the task of early diagnosis of dementing diseases using Magnetic Resonance Imaging. Copyright © 2020, The Authors. All rights reserved.

关键词： Extrapolation

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Comparison of the Effectiveness of Various Structures of Regulators for controlling an Object of the Sixth Order

Comparison of the Effectiveness of Various Structures of Reg...

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2019 International Multi-Conference on engineering, computer and Information sciences, SIBIRCON 2019

作者： Zhmud, Vadim Dimitrov, Lubomir Nosek, Jaroslav Roth, Hubert Novosibirsk State Technical University Dept. of Automation Novosibirsk Russia Technical University of Sofia Sofia Bulgaria Technical University of Liberec Faculty of Mechatronics Computer Science and Interdisciplinary Research Liberec Czech Republic University of Siegen Department of Automatic Control Engineering Siegen Germany Germany

ISBN: (纸本)9781728144016

Object control requires the calculation of a regulator. One of the most effective methods for calculating the regulator is the method of numerical optimization of the regulator. This paper discusses the solution of the problem of controlling a linear object of the sixth order, the parameters of which are such that this high order significantly and negatively affects the possibilities of successfully managing this object. Using the traditional approach to the design problem of the controller (regulator) allows us to formally solve the problem;however, the result of this solution is not satisfactory. The use of additional derivation does not give any noticeable improvement. A solution to this problem is proposed by using pseudo-local feedback, moreover, this connection is supposedly most effective if it covers one of two identical links in the object model. This allows for a smoother attenuation of the frequency response of the object in the region where the action of these two links begins to affect. For pseudo-local communication, an additional PID controller is used, the coefficients of which are also determined by the method of numerical optimization. The optimization result allows us to conclude that the presence of an integral element in this controller is optional. The calculation result of such a composite controller meets the most stringent requirements for the quality of control, since in such a system the speed is increased at least twice, the oscillations, which were about 10% in amplitude, are completely eliminated, the robustness of the system is ensured, which is verified by changing all the controller coefficients by 5% up and down, and also by changing the time constant of the element of the pseudolocal loop by 10% up and down, changes in the transition process of the system in this case remain are acceptable. © 2019 IEEE.

关键词： Feedback

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Prescribed performance control guided policy improvement for satisfying signal temporal logic tasks

arXiv

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arXiv 2019年

作者： Varnai, Peter Dimarogonas, Dimos V. Division of Decision and Control Systems School of Electrical Engineering and Computer Science KTH Royal Institute of Technology Stockholm114 28 Sweden

Signal temporal logic (STL) provides a userfriendly interface for defining complex tasks for robotic systems. Recent efforts aim at designing control laws or using reinforcement learning methods to find policies which guarantee satisfaction of these tasks. While the former suffer from the trade-off between task specification and computational complexity, the latter encounter difficulties in exploration as the tasks become more complex and challenging to satisfy. This paper proposes to combine the benefits of the two approaches and use an efficient prescribed performance control (PPC) base law to guide exploration within the reinforcement learning algorithm. The potential of the method is demonstrated in a simulated environment through two sample navigational tasks. Copyright © 2019, The Authors. All rights reserved.

关键词： Temporal logic

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Distributed Barrier Certificates for Safe Operation of Inverter-Based Microgrids

Distributed Barrier Certificates for Safe Operation of Inver...

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American control Conference

作者： Soumya Kundu Sijia Geng Sai Pushpak Nandanoori Ian A. Hiskens Karan Kalsi Optimization and Control Group Pacific Northwest National Laboratory USA Electrical Engineering and Computer Science University of Michigan Ann Arbor USA

ISBN: (纸本)9781538679012;9781538679265

Inverter-interfaced microgrids differ from the traditional power systems due to their lack of inertia. Vanishing timescale separation between voltage and frequency dynamics makes it critical that faster-timescale stabilizing control laws also guarantee by-construction the satisfaction of voltage limits during transients. In this article, we apply a barrier functions method to compute distributed active and reactive power setpoint control laws that certify satisfaction of voltage limits during transients. Using sum-of-squares optimization tools, we propose an algorithmic construction of these control laws. Numerical simulations are provided to illustrate the proposed method.

关键词： Safe handling voltage limits control law Licence Satisfaction power systems set point control Distribute

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A Pipelining Loop Optimization Method for Dataflow Architecture

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Journal of computer science & Technology 2018年第1期33卷 116-130页

作者： Xu Tan Xiao-Chun Ye Xiao-Wei Shen Yuan-Chao Xu Da Wang Lunkai Zhang Wen-Ming Li Dong-Rui Fan Zhi-Min Tang State Key Laboratory of Computer Architecture Institute of Computing Technology Chinese Academy of Sciences Beijing 100190 China School of Computer and Control Engineering University of Chinese Academy of Sciences Beijing 1000J9 China State Key Laboratory of Mathematical Engineering and Advanced Computing Wuxi 214125 China College of Information Engineering Capital Normal University Beijing 100048 China Department of Computer Science The University of Chicago Chicago IL 60637 U.S.A.

With the coming of exascale supercomputing era, power efficiency has become the most important obstacle to build an exascale system. Dataflow architecture has native advantage in achieving high power efficiency for scientific applications. However, the state-of-the-art dataflow architectures fail to exploit high parallelism for loop processing. To address this issue, we propose a pipelining loop optimization method （PLO）, which makes iterations in loops flow in the processing element （PE） array of dataflow accelerator. This method consists of two techniques, architecture-assisted hardware iteration and instruction-assisted software iteration. In hardware iteration execution model, an on-chip loop controller is designed to generate loop indexes, reducing the complexity of computing kernel and laying a good f（mndation for pipelining execution. In software iteration execution model, additional loop instructions are presented to solve the iteration dependency problem. Via these two techniques, the average number of instructions ready to execute per cycle is increased to keep floating-point unit busy. Simulation results show that our proposed method outperforms static and dynamic loop execution model in floating-point efficiency by 2.45x and 1.1x on average, respectively, while the hardware cost of these two techniques is acceptable.

关键词： dataflow model control-flow model loop optimization exascale computing scientific application

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Colored Petri net model of electrical networks for diagnostic purposes

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IFAC-PapersOnLine 2018年第2期51卷 260-265页

作者： Pózna, A.I. Fodor, A. Gerzson, M. Hangos, K.M. Department of Electrical Engineering and Information Systems University of Pannonia VeszprémH-8201 Hungary Institute for Computer Science and Control Hungarian Academy of Sciences BudapestH-1518 Hungary

A simple and effective colored Petri net (CPN) model is proposed in this paper for a special type of electrical networks that describe local transformer areas, in order to detect and localize illegal loads that may be present. The model is decomposed to characteristic structural elements called feeders with one or two sources the computation of which can be performed independently and in parallel. The CPN model allows to handle the interval-type uncertainties in the model in a transparent and effective way. © 2018

关键词： Electric network parameters

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Gradient-Based STL control with Application to Nonholonomic Systems

arXiv

引用

arXiv 2019年

作者： Varnai, Peter Dimarogonas, Dimos V. Division of Decision and Control Systems School of Electrical Engineering and Computer Science KTH Royal Institute of Technology Stockholm114 28 Sweden

In this paper, we study the control of dynamical systems under temporal logic task specifications using gradient-based methods relying on quantitative measures that express the extent to which the tasks are satisfied. A class of controllers capable of providing satisfaction guarantees for simple systems and specifications is introduced and then extended for the case of unicycle-like dynamics. The possibility of combining such controllers in order to tackle more complex task specifications while retaining their computational efficiency is examined, and the practicalities related to an effective combination are demonstrated through a simulation study. The introduced framework for controller design lays ground for future work in the direction of effectively combining such elementary controllers for the purpose of aiding exploration in learning algorithms. Copyright © 2019, The Authors. All rights reserved.

关键词： controllers

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Image de-blurring Model based on Machine Learning

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Journal of Physics: Conference Series 2021年第2期1952卷

作者： Junsheng Li Silu Xu Cong Wang College of Computer Science and Technology Harbin Engineering University Harbin Heilongjiang 150001 City Institute Dalian University of Technology Dalian Liaoning 1166000 School of Information and Control Engineering Qingdao University of Technology Qingdao Shandong 266520

Due to the influence of haze in winter, outdoor images usually lose contrast and fidelity. In view of the fact that most de-fog algorithms are not effective for images with large sky areas, an improved dark channel a priori de-fog method is proposed. First of all, the sky region is segmented according to the image gradient information, and on the basis of sky segmentation, the atmospheric light value is reasonably estimated by setting the discriminant formula combined with the high brightness and smoothness of atmospheric light reference pixels. Secondly, according to the different dark channel values, the piecewise linear function is used to dynamically modify the adjustable parameters to solve the local shadow caused by excessive defog. Then, the transmittance estimated by the bright channel model and the improved dark channel prior model are fused, and the edge is optimized by guided filtering. Finally, combined with the atmospheric scattering model, the defog image is obtained by brightness compensation and contrast stretching. The experimental results show that the improved method can effectively improve the image distortion, enhance the image contrast and details, especially in maintaining the visual authenticity of the sky region.

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Prescribed Performance control Guided Policy Improvement for Satisfying Signal Temporal Logic Tasks

Prescribed Performance Control Guided Policy Improvement for...

引用

American control Conference

作者： Peter Varnai Dimos V. Dimarogonas Division of Decision and Control Systems School of Electrical Engineering and Computer Science KTH Royal Institute of Technology 114 28 Stockholm Sweden

ISBN: (纸本)9781538679012;9781538679265

Signal temporal logic (STL) provides a user-friendly interface for defining complex tasks for robotic systems. Recent efforts aim at designing control laws or using reinforcement learning methods to find policies which guarantee satisfaction of these tasks. While the former suffer from the trade-off between task specification and computational complexity, the latter encounter difficulties in exploration as the tasks become more complex and challenging to satisfy. This paper proposes to combine the benefits of the two approaches and use an efficient prescribed performance control (PPC) base law to guide exploration within the reinforcement learning algorithm. The potential of the method is demonstrated in a simulated environment through two sample navigational tasks.

关键词： Religious Missions Temporal logic Exploration Simulated Environment Policies Satisfaction Learning Learning methods control law signals

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