• Title/Summary/Keyword: state monitoring. event

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Power Saving Scheme by Distinguishing Traffic Patterns for Event-Driven IoT Applications

  • Luan, Shenji;Bao, Jianrong;Liu, Chao;Li, Jie;Zhu, Deqing
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.13 no.3
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    • pp.1123-1140
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    • 2019
  • Many Internet of Things (IoT) applications involving bursty traffic have emerged recently with event detection. A power management scheme qualified for uplink bursty traffic (PM-UBT) is proposed by distinguishing between bursty and general uplink traffic patterns in the IEEE 802.11 standard to balance energy consumption and uplink latency, especially for stations with limited power and constrained buffer size. The proposed PM-UBT allows a station to transmit an uplink bursty frame immediately regardless of the state. Only when the sleep timer expires can the station send uplink general traffic and receive all downlink frames from the access point. The optimization problem (OP) for PM-UBT is power consumption minimization under a constrained buffer size at the station. This OP can be solved effectively by the bisection method, which demonstrates a performance similar to that of exhaustive search but with less computational complexity. Simulation results show that when the frame arrival rate in a station is between 5 and 100 frame/second, PM-UBT can save approximately 5 mW to 30 mW of power compared with an existing power management scheme. Therefore, the proposed power management strategy can be used efficiently for delay-intolerant uplink traffic in event-driven IoT applications, such as health status monitoring and environmental surveillance.

Clustering based on Dependence Tree in Massive Data Streams

  • Yun, Hong-Won
    • Journal of information and communication convergence engineering
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    • v.6 no.2
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    • pp.182-186
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    • 2008
  • RFID systems generate huge amount of data quickly. The data are associated with the locations and the timestamps and the containment relationships. It is requires to assure efficient queries and updates for product tracking and monitoring. We propose a clustering technique for fast query processing. Our study presents the state charts of temporal event flow and proposes the dependence trees with data association and uses them to cluster the linked events. Our experimental evaluation show the power of proposing clustering technique based on dependence tree.

Monitoring of Machining State in Turning by Means of Information and Feed Motor Current (NC 정보와 이송축 모터 전류를 이용한 선삭 가공 상태 감시)

  • 안중환;김화영
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.16 no.1
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    • pp.156-161
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    • 1992
  • In this research a monitoring system for turning using NC information and the current of feed motor as a monitoring signal was developed. The overall system consists of modules such as learning process, NC data transmission, generation of forecast information, signal acquisition, monitoring and post process. In the learning process, the reference data and the cutting force equation necessary for monitoring are obtained from the accumulated monitoring results. In the generation of forecast information, the information of forecasted cutting forces is acquired from the cutting force equation and NC program and appended to each NC block as a monitor code. Reliability of monitoring is improved by using the monitor code in the real-time monitoring. Monitoring module is divided into two parts : the off-line monitoring where errors of NC program are checked and the on-line monitoring where the level of motor current is monitored during cutting operations. If the actual current level exceeds the limit value provided by the monitor code in the level monitoring, it is recognized as abnormal. In the event of abnormal status, the post processor sends the emergency stop signal to NC controller to stop the operation. Actual experiments have shown that the developed monitoring system works well.

A Study on the Monitoring of Pressure Vessel Safety during Hydrotest by Acoustic Emission (AE에 의한 압력용기의 안전성평가에 관한 연구)

  • Lee, J.S.;Cho, K.S.;Choi, J.M.;Chang, H.K.;Oh, S.K.
    • Journal of the Korean Society for Nondestructive Testing
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    • v.8 no.1
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    • pp.12-21
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    • 1988
  • The behaviour of pressure vessel made of SS41 steel was investigated during hydrotest. AE tests were carried out for the vessels in as-manufactured, V-notched and weld-cracked state using microcomputer-based AE instrumentation. The following results were obtained: 1) In the case of source location using cylindrical program, to minimize the error of source location, the difference of max. Delta T values measured from each sensor should be kept as small as possible. 2) When crack grew, AE event rate increased continuously but AE event from the inclusions occurred intermittently, so by analyzing event rate, the source of AE could be derived. 3) From the spot welding part of supporter, many events with low energy occurred independent of Kaiser effect, which could be confirmed by analyzing energy parameter. 4) The b-value from the tensile specimen of was lower than that from normal specimen and the b-value from crack propagation was lower than that from deformation, so by analyzing peak amplitude distribution, the source mechanism could be derived from the b-value.

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Robust Process Fault Detection System Under Asynchronous Time Series Data Situation (비동기 설비 신호 상황에서의 강건한 공정 이상 감지 시스템 연구)

  • Ko, Jong-Myoung;Choi, Ja-Young;Kim, Chang-Ouk;Sun, Sang-Joon;Lee, Seung-Jun
    • IE interfaces
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    • v.20 no.3
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    • pp.288-297
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    • 2007
  • Success of semiconductor/LCD industry depends on its yield and quality of product. For the purpose, FDC (Fault Detection and Classification) system is used to diagnose fault state in main manufacturing processes by monitoring time series data collected by equipment sensors which represent various conditions of the equipment. The data set is segmented at the start and end of each product lot processing by a trigger event module. However, in practice, segmented sensor data usually have the features of data asynchronization such as different start points, end points, and data lengths. Due to the asynchronization problem, false alarm (type I error) and missed alarm (type II error) occur frequently. In this paper, we propose a robust process fault detection system by integrating a process event detection method and a similarity measuring method based on dynamic time warping algorithm. An experiment shows that the proposed system is able to recognize abnormal condition correctly under the asynchronous data situation.

An Autonomous Command Recommend and Execution System for the Satellite Operation (위성 운영을 위한 이벤트 시퀀스 기반의 자동 명령 추천 및 수행 시스템)

  • Yang, Seung-Eun;Jung, Jae-Yeop;Cheon, Yee-Jin
    • Aerospace Engineering and Technology
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    • v.13 no.2
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    • pp.29-37
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    • 2014
  • Telemetry, satellite event and error information are used to check the satellite status in ground station. Different from telemetry which only informs the parameter value, event and error gives explicit information of a certain operation or status. Event also contains ground action information because every command execution is logged as event. Currently, those information is gathered and applied only for monitoring of the satellite. However, the load of the operation is getting grown because of the excessively increased information of the satellite with the number of satellite increasement. Also, the process of reporting problem to developer (or an expert) induce time delay for satellites fault management. In this paper, we propose a satellite operation assistant system which collects event sequence and stores in different group by its feature, and then recommends or executes an appropriate action for the identified abnormal state. This system is applicable to on board system for resolving LEO-satellite autonomous fault situation since is has limited contact time.

Monitoring Technique using Acoustic Emission and Microseismic Event (AE와 MS 이벤트를 이용한 계측기술)

  • Cheon, Dae-Sung;Jung, Yong-Bok;Park, Chul-Whan;Synn, Joong-Ho;Park, Eui-Seob
    • Tunnel and Underground Space
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    • v.18 no.1
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    • pp.1-9
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    • 2008
  • Acoustic emission (AE) and Microseimsic (MS) activities are law-energy seismic events associated with a sudden inelastic deformation such as the sudden movement of existing fractures, the generation of new fractures or the propagation of fractures. These events rapidly increase before major failure and happen within a given rock volume and radiate detectable seismic waves. The main difference between AE and MS signals is that the seismic motion frequencies of AE signals are higher than those of MS signals. As the failure of geotechnical structures usually happens as a high velocity and small displacement, it is nat easy ta determine the precursor and initiation stress level of failure in displacement detection method. To overcame this problem, AE/MS techniques far detection of structure failure and damage have recently adapt in civil engineering. This study deal with the basic theory of AE/MS and state of arts in monitoring technique using AE/MS.

Vibration Monitoring and Diagnosis System Framework for 3MW Wind Turbine (3MW 풍력발전기 진동상태감시 및 진단시스템 프레임워크)

  • Son, Jong-Duk;Eom, Seung-Man;Kim, Sung-Tae;Lee, Ki-Hak;Lee, Jeong-Hoon
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.25 no.8
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    • pp.553-558
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    • 2015
  • This paper aims at making a dedicated vibration monitoring and diagnosis framework for 3MW WTG(wind turbine generator). Within the scope of the research, vibration data of WTG drive train are used and WTG operating conditions are involved for dividing the vibration data class which included transient and steady state vibration signals. We separate two health detections which are CHD(continuous health detection) and EHD(event health detection). CHD has function of early detection and continuous monitoring. EHD makes the use of finding vibration values of fault components effectively by spectrum matrix subsystem. We proposed framework and showed application for 3MW WTG in a practical point of view.

Impact test of a centrifugal pump used in nuclear power plant under aircraft crash scenario

  • Huang, Tao;Chen, Mengmeng;Li, Zhongcheng;Dong, Zhanfa;Zhang, Tiejian;Zhou, Zhiguang
    • Nuclear Engineering and Technology
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    • v.53 no.6
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    • pp.1858-1868
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    • 2021
  • Resisting an accidental impact of large commercial aircrafts is an important aspect of advanced nuclear power plant (NPP) design. Especially after the 9·11 event, some regulations were enacted, which required the design of NPPs should consider the accidental impact of large commercial aircrafts. Normal working of equipment is important for stopping reactor under an impact when an NPP is in operation. However, there is a lack of reliable analysis and research on the impact test of nuclear prototype equipment. Therefore, in order to study the response of the equipment under high acceleration impact, a centrifugal pump is selected as the research object to perform the impact test. A horizontal half-sinusoidal pulse wave was applied to the working pump. The test results show that the horizontal response of the motor and flange is greater compared to other parts, as well as the vertical response of the coupling. The stress response of the pump body support and motor support is high, hence these parts should be considered in the design of the pump. Finally, combined with the damage and stress evaluation results of the pump under different amplitudes, the ultimate impact acceleration that the pump can withstand is given.

Damage and vibrations of nuclear power plant buildings subjected to aircraft crash part II: Numerical simulations

  • Li, Z.R.;Li, Z.C.;Dong, Z.F.;Huang, T.;Lu, Y.G.;Rong, J.L.;Wu, H.
    • Nuclear Engineering and Technology
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    • v.53 no.9
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    • pp.3085-3099
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    • 2021
  • Investigations of large commercial aircraft impact effect on nuclear power plant (NPP) buildings have been drawing extensive attentions, particularly after the 9/11 event, and this paper aims to numerically assess the damage and vibrations of NPP buildings subjected to aircrafts crash. In Part I of present paper, two shots of reduce-scaled model test of aircraft impact on NPP were conducted based on the large rocket sled loading test platform. In the present part, the numerical simulations of both scaled and prototype aircraft impact on NPP buildings are further performed by adopting the commercial program LS-DYNA. Firstly, the refined finite element (FE) models of both scaled aircraft and NPP models in Part I are established, and the model impact test is numerically simulated. The validities of the adopted numerical algorithm, constitutive model and the corresponding parameters are verified based on the experimental NPP model damages and accelerations. Then, the refined simulations of prototype A380 aircraft impact on a hypothetical NPP building are further carried out. It indicates that the NPP building can totally withstand the impact of A380 at a velocity of 150 m/s, while the accompanied intensive vibrations may still lead to different levels of damage on the nuclear related equipment. Referring to the guideline NEI07-13, a maximum acceleration contour is plotted and the shock damage propagation distances under aircraft impact are assessed, which indicates that the nuclear equipment located within 11.5 m from the impact point may endure malfunction. Finally, by respectively considering the rigid and deformable impacts mainly induced by aircraft engine and fuselage, an improved Riera function is proposed to predict the impact force of aircraft A380.