• Title/Summary/Keyword: Reducing Pressure Control

검색결과 255건 처리시간 0.025초

Effective simulation-based optimization algorithm for the aircraft runway scheduling problem

  • Wided, Ali;Fatima, Bouakkaz
    • Advances in aircraft and spacecraft science
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    • 제9권4호
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    • pp.335-347
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    • 2022
  • Airport operations are well-known as a bottleneck in the air traffic system, putting growing pressure on the world's busiest airports to schedule arrivals and departures as efficiently as possible. Effective planning and control are essential for increasing airport efficiency and reducing aircraft delays. Many algorithms for controlling the arrival/departure queuing area are handled, considering it as first in first out queues, where any available aircraft can take off regardless of its relative sequence with other aircraft. In the suggested system, this problem was compared to the problem of scheduling n tasks (plane takeoffs and landings) on a multiple machine (runways). The proposed technique decreases delays (via efficient runway allocation or allowing aircraft to be expedited to reach a scheduled time) to enhance runway capacity and decrease delays. The aircraft scheduling problem entails arranging aircraft on available runways and scheduling their landings and departures while considering any operational constraints. The topic of this work is the scheduling of aircraft landings and takeoffs on multiple runways. Each aircraft's takeoff and landing schedules have time windows, as well as minimum separation intervals between landings and takeoffs. We present and evaluate a variety of comprehensive concepts and solutions for scheduling aircraft arrival and departure times, intending to reduce delays relative to scheduled times. When compared to First Come First Serve scheduling algorithm, the suggested strategy is usually successful in reducing the average waiting time and average tardiness while optimizing runway use.

Feedback control strategies for active control of noise inside a 3-D vibro-acoustic cavity

  • Bagha, Ashok K.;Modak, Subodh V.
    • Smart Structures and Systems
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    • 제20권3호
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    • pp.273-283
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    • 2017
  • This paper presents and compares three feedback control strategies for active control of noise inside a 3-D vibro-acoustic cavity. These are a) control strategy based on direct output feedback (DOFB) b) control strategy based on linear quadratic regulator (LQR) to reduce structural vibrations and c) LQR control strategy with a weighting scheme based on structural-acoustic coupling coefficients. The first two strategies are indirect control strategies in which noise reduction is achieved through active vibration control (AVC), termed as AVC-DOFB and AVC-LQR respectively. The third direct strategy is based on active structural-acoustic control (ASAC). This strategy is an LQR based optimal control strategy in which the coupling between the various structural and the acoustic modes is used to design the controller. The strategy is termed as ASAC-LQR. A numerical model of a 3-D rectangular box cavity with a flexible plate (glued with piezoelectric patches) and with other five surfaces treated rigid is developed using finite element (FE) method. A single pair of collocated piezoelectric patches is used for sensing the vibrations and applying control forces on the structure. A comparison of frequency response function (FRF) of structural nodal acceleration, acoustic nodal pressure, and piezoelectric actuation voltage is carried out. It is found that the AVC-DOFB control strategy gives equal importance to all the modes. The AVC-LQR control strategy tries to consume the control effort to damp all the structural modes. It is seen that the ASAC-LQR control strategy utilizes the control effort more intelligently by adding higher damping to those structural modes that matter more for reducing the interior noise.

이압요법이 퇴행성 슬관절염 노인의 관절 통증, 관절 가동범위 및 수면에 미치는 효과 (Effects of Auricular Acupressure on Joint Pain, Range of Motion, and Sleep in the Elderly with Knee Osteoarthritis)

  • 장민진;임윤미;박효정
    • 지역사회간호학회지
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    • 제30권1호
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    • pp.79-89
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    • 2019
  • Purpose: The purpose of this paper is to determine effects of auricular acupressure on knee pain, range of motion, and sleep in the elderly with knee osteoarthritis. Methods: This is an experimental study designed with randomization and single-blind in a placebo-control approach. The subjects included the elderly with knee osteoarthritis who were using an elderly welfare facility. In each of the groups, 28 subjects were assigned. For the experimental group, auricular acupressure was applied to five pressure points related to the pain caused by osteoarthritis and sleep. In the case of the placebo-control group, auricular acupressure was applied to other five points than the former. The intervention lasted eight weeks. In order to examine intervention effects of auricular acupressure, joint pain, Pressure Pain Thresholds (PPTs), and extension and flexion range of motion (ROM) were measured weekly. As for the preand post-examinations, pain, sleep quality, and the time-by-sleep stage of the patients with knee osteoarthritis were measured. Results: The VAS scores in the experimental group with auricular acupressure significantly decreased through time (p<.001) and WOMAC also significantly decreased (p<.01) compared with the placebo-control group. However, there were no significant differences in PPTs. The flexion (p<.01) and extension (p<.001) ROMs measured for eight weeks improved over time. Meanwhile, sleep quality improved significantly after the intervention termination (p<.01), but there was no significant difference found in the time-by-sleep stage. Conclusion: Auricular acupressure applied for eight weeks was found to be effective in reducing joint pain, improving knee ROM, and improving sleep quality in patients with degenerative knee arthritis.

Effects of a Combination of Scapular Stabilization and Thoracic Extension Exercises on Respiration, Pain, Craniovertebral Angle and Cervical Range of Motion in Elementary School Teachers with a Forward Head Posture: A Randomized Controlled Trial

  • Kang, Na-Yeon;Kim, Kyoung
    • 대한물리의학회지
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    • 제17권2호
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    • pp.29-40
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    • 2022
  • PURPOSE: This study examined the effects of an exercise program for the thoracic spine and scapula rather than the neck, which is the primary site of pain. METHODS: Thirty-two elementary school teachers with a forward head posture (FHP) were assigned randomly to either the experimental group (n = 16) or the control group (n = 16). The experimental group performed scapular stabilization exercise (SSE) and thoracic extension exercise (TEE), and the control group performed cervical self-myofascial release exercise and stretching exercise. The pulmonary functions, pain, craniovertebral angle (CVA), and cervical range of motion (CROM) were measured before the intervention and six weeks after. RESULTS: The within-group comparisons showed that the VAS and CROM (except for extension) in both groups were significantly different before and after the intervention (p < .05). The changes in the maximum inspiratory pressure (MIP), maximum expiratory pressure (MEP), forced vital capacity (FVC), forced expiratory volume at 1 sec (FEV1), and CVA were significant only in the experimental group (p < .05). The between-group comparisons showed a significant difference in the FVC, FEV1, VAS, CVA, and left lateral flexion (p < .05). CONCLUSION: The combination of SSE and TEE in the experimental group was more effective in improving the FHP and breathing ability. Moreover, the experimental group and control combination appeared to be effective in reducing pain and improving the CROM. The combination of SSE and TEE, which are exercises that do not target the cervical spine directly, was effective in improving the posture, respiration, neck pain, and CROM in elementary school teachers with FHP.

손마사지와 손잡아주기가 국소마취 수술환자의 불안에 미치는 영향 (Effects of Hand Massage and Hand Holding on the Anxiety in Patients with Local Infiltration Anesthesia)

  • 오현정;박정숙
    • 대한간호학회지
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    • 제34권6호
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    • pp.924-933
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    • 2004
  • Purpose: This study was to examine the effects of hand massage and hand holding as nursing interventions on the anxiety in patients with local infiltration anesthesia. Method: The design of this study was a nonequivalent, control group, non- synchronized design. The subjects of this study consisted of 15 patients for the hand massage group, 15 patients for the hand holding group and 17 patients for the control group awaiting surgery in the operation room of a general hospitalin Daegu. As an experimental treatment, hand massage was carried out by the Hand Massage Protocol developed by Snyder(1995) and interpreted by Cho(1998) and hand holding developed by Cho(1998). The data were analyzed by SPSS/WIN, T-test, ANOVA, Cronbach's a, and the Scheffe test. Results: The hand massage group and hand holding group were more effective than the control group in reducing anxiety, VAS score, systolic blood pressure and pulse rate. Conclusion: Hand massage and hand holding are effective nursing interventions that alleviates the psychological and physiological anxiety of patients with local infiltration anesthesia. In particular, the simple contact of hand holding is regarded as an effective and easily accessible nursing intervention in the operating room.

굴삭기 IMV용 비례전자밸브의 동특성 (Dynamic Characteristics of Electro-hydraulic Proportional Valve for an Independent Metering Valve of Excavator)

  • 강창남;윤소남;정황훈;김문곤
    • 드라이브 ㆍ 컨트롤
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    • 제15권2호
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    • pp.46-51
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    • 2018
  • Many research studies have been carried out related to saving energy and environmental pollution in the field of construction machinery. The best solution for reducing the related environmental pollution is to reduce fuel consumption by upgrading the energy efficiency of machinery used in this field. An efficiency upgrade in the field of construction machinery would mean minimizing the pressure loss in hydraulic pipe lines or achieving optimal operating conditions while responding to a load. One way to achieve this is to make an equivalent circuit, like an electrohydrostatic actuator, or to improve the spool type valve using the 4/3 way method. This study deals with an electrohydraulic proportional flow control valve. SimulationX software is used as a simulation tool for analyzing the dynamic characteristics. The analysis results, including the performance and characteristics of design parameters, are discussed and the validity of the theoretical analysis is also evaluated.

Optical In-Situ Plasma Process Monitoring Technique for Detection of Abnormal Plasma Discharge

  • Hong, Sang Jeen;Ahn, Jong Hwan;Park, Won Taek;May, Gary S.
    • Transactions on Electrical and Electronic Materials
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    • 제14권2호
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    • pp.71-77
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    • 2013
  • Advanced semiconductor manufacturing technology requires methods to maximize tool efficiency and improve product quality by reducing process variability. Real-time plasma process monitoring and diagnosis have become crucial for fault detection and classification (FDC) and advanced process control (APC). Additional sensors may increase the accuracy of detection of process anomalies, and optical monitoring methods are non-invasive. In this paper, we propose the use of a chromatic data acquisition system for real-time in-situ plasma process monitoring called the Plasma Eyes Chromatic System (PECS). The proposed system was initially tested in a six-inch research tool, and it was then further evaluated for its potential to detect process anomalies in an eight-inch production tool for etching blanket oxide films. Chromatic representation of the PECS output shows a clear correlation with small changes in process parameters, such as RF power, pressure, and gas flow. We also present how the PECS may be adapted as an in-situ plasma arc detector. The proposed system can provide useful indications of a faulty process in a timely and non-invasive manner for successful run-to-run (R2R) control and FDC.

Development of partial liquefaction system for liquefied natural gas carrier application using exergy analysis

  • Choi, Jungho
    • International Journal of Naval Architecture and Ocean Engineering
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    • 제10권5호
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    • pp.609-616
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    • 2018
  • The cargo handling system, which is composed of a fuel gas supply unit and cargo tank pressure control unit, is the second largest power consumer in a Liquefied Natural Gas (LNG) carrier. Because of recent enhancements in ship efficiency, the surplus boil-off gas that remains after supplying fuel gas for ship propulsion must be reliquefied or burned to regulate the cargo tank pressure. A full or partial liquefaction process can be applied to return the surplus gas to the cargo tank. The purpose of this study is to review the current partial liquefaction process for LNG carriers and develop new processes for reducing power consumption using exergy analysis. The developed partial liquefaction process was also compared with the full liquefaction process applicable to a LNG carrier with a varying boil-off gas composition and varying liquefaction amounts. An exergy analysis showed that the Joule-Thomson valve is the key component needed for improvements to the system, and that the proposed system showed an 8% enhancement relative to the current prevailing system. A comparison of the study results with a partial/full liquefaction process showed that power consumption is strongly affected by the returned liquefied amount.

2 리터급 터보과급 가솔린 기관에서 내장형 WGV가 기관 성능에 미치는 영향 (The Effect of the Embedded WGV on the Engine Performance for a 2-liter Turbo-charged Gasoline Engine)

  • 장종관
    • 한국자동차공학회논문집
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    • 제24권2호
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    • pp.232-241
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    • 2016
  • The turbocharger, to decrease the harmful exhaust gas(CO, HC and etc.) and $CO_2$ emission as well as the increase of the engine output, would be an useful method for engine downsizing. Therefore the thermal endurance of turbine blade, the lubrication of turbine shaft and the engine knock according to the supercharge of the inlet air, had been studied. And there had been much progress in these research tasks to be achieved a breakthrough. But a study on the built-in WGV of a gasoline engine for a passenger car which may effect on the engine performance, is few. In this paper, the effect of the embedded WGV on the engine performance was performed through the endurance test, which was conducted more than 300 hrs using the 4 stroke, 1998 cc, water-cooled engine. To sum up the major results, there were an abrasion in the area of the WGV head edge and the thermal deformation on the WGV head face, These phenomena led to reducing the boost pressure which caused the reduction in the volumetric efficiency of the engine. It resulted in decreasing the engine power gradually during the life cycle of the embedded WGV.

저소음 저배압을 위한 다중모드 배기계의 소음제어 (Control of the Multi-Mode Muffler for Low Noise and Low Backpressure)

  • 손동구;김흥섭;오재응
    • 대한기계학회논문집A
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    • 제24권6호
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    • pp.1371-1378
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    • 2000
  • To reduce backpressure for improving engine power in exhaust system, a large difference of pressure is required, but this is in conflict with the requirement for reducing exhaust noise that needs a small pressure difference. In this paper, the controllable muffler designed by simplifying the structure of the exhaust system has a low backpressure and a proper sound specification to the rotation of engine. The exhaust system in conventional studies has been designed to have maximum noise reduction over the whole driving domain, but due to its complex structure this led to increased backpressure. If the muffler is designed according to the driving frequency, which is a dominant noise component in stationary driving speed, the backpressure is reduced due to the simplified structure of the muffler. Furthermore, a multi-mode muffler able to change structure with varied driving speed was designed.