• Title/Summary/Keyword: Hard real-time

Search Result 505, Processing Time 0.033 seconds

An Integer Programming Approach to the Problem of Daily Crew Scheduling (일간승무계획문제의 정수계획해법)

  • 변종익;이경식;박성수
    • Proceedings of the Korean Operations and Management Science Society Conference
    • /
    • 2000.04a
    • /
    • pp.613-616
    • /
    • 2000
  • This paper considers the problem of subway crew scheduling. Crew scheduling is concerned with finding a minimum number of assignments of crews to a given timetable satisfying various restrictions. Traditionally, crew scheduling problem has been formulated as a set covering or set partitioning problem possessing exponentially many variables, but even the LP relaxation of the problem is hard to solve due to the exponential number of variables. In this paper, we propose two basic techniques that solve the problem in a reasonable time, though the optimality of the solution is not guaranteed. To reduce the number of variables, we adopt column-generation technique. We could develop an algorithm that solves column-generation problem in polynomial time. In addition, the integrality of the solution is accomplished by variable-fixing technique. Computational results show column-generation makes the problem of treatable size, and variable fixing enables us to solve LP relaxation in shorter time without a considerable increase in the optimal value. Finally, we were able to obtain an integer optimal solution of a real instance within a reasonable time.

  • PDF

An Efficient DVS Algorithm for Pinwheel Task Schedules

  • Chen, Da-Ren;Chen, You-Shyang
    • Journal of Information Processing Systems
    • /
    • v.7 no.4
    • /
    • pp.613-626
    • /
    • 2011
  • In this paper, we focus on the pinwheel task model with a variable voltage processor with d discrete voltage/speed levels. We propose an intra-task DVS algorithm, which constructs a minimum energy schedule for k tasks in O(d+k log k) time We also give an inter-task DVS algorithm with O(d+n log n) time, where n denotes the number of jobs. Previous approaches solve this problem by generating a canonical schedule beforehand and adjusting the tasks' speed in O(dn log n) or O($n^3$) time. However, the length of a canonical schedule depends on the hyper period of those task periods and is of exponential length in general. In our approach, the tasks with arbitrary periods are first transformed into harmonic periods and then profile their key features. Afterward, an optimal discrete voltage schedule can be computed directly from those features.

Development of a CAN-based Real-time Simulator for Car Body Control

  • Kang, Ki-Ho;Seong, Sang-Man
    • 제어로봇시스템학회:학술대회논문집
    • /
    • 2005.06a
    • /
    • pp.444-448
    • /
    • 2005
  • This paper presents a developing procedure of the CAN-based real-time simulator for car body control, aiming at replacing the actual W/H (Wiring Harness) and J/B(Junction Box) couple eventually. The CAN protocol, as one kind of field-bus communication, defines the lowest 2 layers of the ISO/OSI standard, namely, the physical layer(PL) and the data link layer(DLL), for which the CSMA/NBA protocol is generally adopted. For CPU, two PIC18Fxx8x's are used because of their built-in integration of CAN controller, large internal FLASH memory (48K or 64K), and their costs. To control J/B's and actuators, 2 controller boards are separately implemented, between which CAN lines communicate through CAN transceivers MCP255. A power motor for washing windshield, 1 door lock motor, and 6 blink lamps are chosen for actuators of the simulator for the first stage. For the software architecture, a polling method is used for the fast global response time despite its slow individual response time. To improve the individual response time and to escape from some eventual trapped-function loops, High/Low ports of the CPU are simply used, which increases the stability of the actuator modules. The experimental test shows generally satisfactory results in normal transmitting / receiving function and message trace function. This simulator based on CAN shows a promising usefulness of lighter, more reliable and intelligent distributed body control approach than the conventional W/H and J/B couple. Another advantage of this approach lies in the distributed control itself, which gives better performance in hard real-time computing than centralized one, and in the ability of integrating different modules through CAN.

  • PDF

Study of the Effects of Sa-am Acupuncture on Upper Limb Spasticity in Patients with Chronic Post-stroke Hemiparesis using Real-time Sonoelastography (실시간 탄성초음파를 이용한 만성 뇌졸중 후 편마비 환자의 상지 강직에 대한 사암침 효과 연구)

  • Baek, Kyung-Min;Kwon, Dong-Rak;Park, Gi-Young
    • The Journal of Internal Korean Medicine
    • /
    • v.35 no.1
    • /
    • pp.1-11
    • /
    • 2014
  • Objectives : To investigate the effects of Sa-am acupuncture on muscle architecture and elastic properties of the spastic elbow flexor and to evaluate the correlation between clinical findings and parameters of real-time sonoelastography (RTS) in patients with chronic post-stroke hemiparesis. Materials and Methods : Seven patients (five males, two females) with chronic post-stroke hemiparesis were included. Sa-am acupuncture of Ganseunggyeok (肝勝格: LU8 LR4 補, HT8 LR2 瀉) was applied to the unaffected side 3 times a week for 4 weeks. During each acupuncture treatment period, patients were requested to exercise their affected arm, and spasticity and functional recovery outcomes of the affected arm were evaluated before and after Sa-am acupuncture treatment. Clinical outcomes were assessed using motricity index (MI), modified Ashworth scale (MAS), Fugl-Meyer assessment scale (FMA) and modified Barthel index (MBI) for elbow flexor spasticity. RTS images indicate the relative hardness of the examined muscles ranged from red (hard) to purple (soft) for color-scale, and from black (hard) to white (soft) for hue scale. Color and hue histograms of the biceps brachii and brachialis were analyzed using Image J software, and median red, blue, and hue pixel intensity were obtained. Results : MI and FMA score significantly increased and MAS score significantly decreased (p<0.05). F-wave maximal amplitude of affected abductor pollicis brevis significantly decreased (p<0.05). Muscle thickness of affected brachialis significantly increased (p<0.05). Red and green pixel intensity of affected brachialis significantly decreased (p<0.05). Conclusions : Our study revealed that Sa-am acupuncture is effective as a useful and safe treatment for spasticity in chronic post-stroke hemiparesis.

Improvement of Reliability of Static Execution Time Analysis Using Software Monitoring Technique (소프트웨어 감시 기법을 활용한 정적 실행시간 분석의 신뢰성 향상)

  • Kim, Yun-Kwan;Kim, Tae-Wan;Chang, Chun-Hyon
    • Journal of the Korea Society of Computer and Information
    • /
    • v.15 no.4
    • /
    • pp.37-45
    • /
    • 2010
  • A system which needs timely accuracy has to design and to verify correctly about execution-time for reliability. Accordingly, it is necessary for timing analysis tools, and much previous research worked. In timing analysis tool, there are two methods. One is a static analysis, and the other is a measurement based analysis. A static analysis is able to spend time less than a measurement based analysis method, but has low reliability of analysis result caused by hard to estimate time of I/O caused by various hardware. A measurement based analysis can be close analysis to real result, but it is hard to adapt to actual application, and spend a lot of time to get result of analysis. As such, this paper present a software monitoring architecture to supply reliability of static analysis process. In a presented architecture, it can select target as needed measurement through static analysis, and reuse result of measurement exist. Therefore, The architecture can reduce overload of time and performance for measurement, and improve the reliability which is the worst problem of static analysis.

Development of Wireless Base Station Re4mote Monitoring System Using IoT Based on Cloud Server (클라우드 서버 기반 IoT를 이용한 무선기지국 원격 감시시스템 개발)

  • Lee, Yang-Weon;Kim, Chul-Won
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
    • /
    • 2018.05a
    • /
    • pp.491-494
    • /
    • 2018
  • Radio base stations, which are widely distributed across large areas, have many difficulties in managing them. Unmanned radio base stations in remote mountains are having a hard time accessing them in case of emergencies. Major telephone service providers only remotely control incoming and outgoing information and local small business partners responsible for maintaining actual facilities do not possess such technologies, so they are each checked during field visits. In this study, in order to monitor temperature, humidity, fire condition, and power operation at a wide range of radio base stations, real-time monitoring is carried out at the office of Klaus server through real-time monitoring.

  • PDF

Fine Grain Real-Time Code Scheduling Using an Adaptive Genetic Algorithm (적합 유전자 알고리즘을 이용한 실시간 코드 스케쥴링)

  • Chung, Tai-Myoung
    • The Transactions of the Korea Information Processing Society
    • /
    • v.4 no.6
    • /
    • pp.1481-1494
    • /
    • 1997
  • In hard real-time systems, a timing fault may yield catastrophic results. Dynamic scheduling provides the flexibility to compensate for unexpected events at runtime; however, scheduling overhead at runtime is relatively large, constraining both the accuracy of the timing and the complexity of the scheduling analysis. In contrast, static scheduling need not have any runtime overhead. Thus, it has the potential to guarantee the precise time at which each instruction implementing a control action will execute. This paper presents a new approach to the problem of analyzing high-level language code, augmented by arbitrary before and after timing constraints, to provide a valid static schedule. Our technique is based on instruction-level complier code scheduling and timing analysis, and can ensure the timing of control operations to within a single instruction clock cycle. Because the search space for a valid static schedule is very large, a novel adaptive genetic search algorithm was developed.

  • PDF

Dynamic Bandwidth Allocation of CAN-based Network using increments of signal applied to Marine Engine Monitoring System (신호 증감 량을 이용한 CAN 기반 선박 엔진 모니터링 시스템의 동적인 대역폭 할당)

  • Lee, Hyun;Lee, Jun-Seok;Lim, Hyun-Seop;Lee, Jang-Myung
    • The Transactions of The Korean Institute of Electrical Engineers
    • /
    • v.61 no.6
    • /
    • pp.838-844
    • /
    • 2012
  • This paper proposes the effective monitoring method for marine engine system, which is implemented based upon Controller Area Network (CAN). As the marine engine monitoring system requires various kind of information, a lot of sensor nodes are distributed to several places. The CAN supports huge numbers of message IDs for the sensor nodes and provides a stable communication channel in a wide area such as a 12,000 TEU container ship. Since the CAN is priority-based communication system, some of hard real-time messages like alarm messages which are time-critical to the operation of the vessel cannot be communicated within the dead-time. Therefore it is desirable to distinguish the bandwidth of the CAN for static state messages and transition-state messages not to be harmful to the engine operations. Using the features of message arbitration ability of the CAN, it is proposed in this paper that the bandwidth allocation is dynamically adjusted to cope with the increment of input signal to improve the performance of monitoring system. Effectiveness and validity of the proposed scheme have been demonstrated through real experiments.

Development of Integrated Operating Program for Inshore Test Miner and its Simulator (근해역 시험집광기용 통합운용 프로그램 및 시뮬레이터 개발)

  • Lee, Do-Kyoung;Yoon, Suk-Min;Park, Soung-Jea;Yeu, Tae-Kyeong;Hong, Sup;Kim, Hak-Kyeong;Kim, Sang-Bong
    • Journal of Ocean Engineering and Technology
    • /
    • v.23 no.4
    • /
    • pp.78-84
    • /
    • 2009
  • This paper presents development results of integrated operating program and its simulator for an inshore test miner. The inshore test miner drives on the seabed and collects manganese nodules. For operating the test miner, integrated operating program (IOP) is needed for remote control and monitor of the miner in real-time. However, it is hard to develop the practical IOP for the test miner system, because the system is big, expensive, and unique. So a simulator was developed as a test substitute in order to save time and to reduce cost. Using test results of the simulator, the IOP of the test miner was developed. The developed IOP consists of remote program, host program, monitoring program and database program. The operating program was developed using PXI and Labview of NI. The experimental results are presented to show the applicability of the developed program.

Multiple Path Based Vehicle Routing in Dynamic and Stochastic Transportation Networks

  • Park, Dong-joo
    • Proceedings of the KOR-KST Conference
    • /
    • 2000.02a
    • /
    • pp.25-47
    • /
    • 2000
  • In route guidance systems fastest-path routing has typically been adopted because of its simplicity. However, empirical studies on route choice behavior have shown that drivers use numerous criteria in choosing a route. The objective of this study is to develop computationally efficient algorithms for identifying a manageable subset of the nondominated (i.e. Pareto optimal) paths for real-time vehicle routing which reflect the drivers' preferences and route choice behaviors. We propose two pruning algorithms that reduce the search area based on a context-dependent linear utility function and thus reduce the computation time. The basic notion of the proposed approach is that ⅰ) enumerating all nondominated paths is computationally too expensive, ⅱ) obtaining a stable mathematical representation of the drivers' utility function is theoretically difficult and impractical, and ⅲ) obtaining optimal path given a nonlinear utility function is a NP-hard problem. Consequently, a heuristic two-stage strategy which identifies multiple routes and then select the near-optimal path may be effective and practical. As the first stage, we utilize the relaxation based pruning technique based on an entropy model to recognize and discard most of the nondominated paths that do not reflect the drivers' preference and/or the context-dependency of the preference. In addition, to make sure that paths identified are dissimilar in terms of links used, the number of shared links between routes is limited. We test the proposed algorithms in a large real-life traffic network and show that the algorithms reduce CPU time significantly compared with conventional multi-criteria shortest path algorithms while the attributes of the routes identified reflect drivers' preferences and generic route choice behaviors well.

  • PDF