• Title/Summary/Keyword: permanent displacement

Search Result 195, Processing Time 0.03 seconds

A Design on Reduction Cogging Torque of Dual Generator Radial Flux Permanent Magnet Generator for Small Wind Turbine

  • Lee, Gyeong-Chan;Jung, Tae-Uk
    • Journal of Electrical Engineering and Technology
    • /
    • v.8 no.6
    • /
    • pp.1590-1595
    • /
    • 2013
  • In this paper, the design for an electromagnetic structure and reduction cogging torque of a dual generator structured RFPM generator, which is a combination of the inner- and outer-rotor types, has been proposed. We call this a dual generator radial flux permanent magnet generator. To reduce the cogging torque, firstly, stator tooth pairing was designed; secondly, stator displacement was designed and finally, stator tooth pairing and stator displacement were carried out simultaneously. We found the optimal design condition about stator tooth pairing angle combination and stator displacement angle for cogging torque minimization. As a result, a cogging was reduced by 93.3[%] by this study.

Optimal Design of Permanent Magnet Actuator Using Parallel Genetic Algorithm (병렬유전 알고리즘을 이용한 영구자석형 액추에이터의 최적설계)

  • Kim, Joong-Kyoung;Lee, Cheol-Gyun;Kim, Han-Kyun;Hahn, Sung-Chin
    • The Transactions of The Korean Institute of Electrical Engineers
    • /
    • v.57 no.1
    • /
    • pp.40-45
    • /
    • 2008
  • This paper presents an optimal design of a permanent magnet actuator(PMA) using a parallel genetic algorithm. Dynamic characteristics of permanent magnet actuator model are analyzed by coupled electromagnetic-mechanical finite element method. Dynamic characteristics of PMA such as holding force, operating time, and peak current are obtained by no load test and compared with the analyzed results by coupled finite element method. The permanent magnet actuator model is optimized using a parallel genetic algorithm. Some design parameters of vertical length of permanent magnet, horizontal length of plunger, and depth of permanent magnet actuator are predefined for an optimal design of permanent magnet actuator model. Furthermore dynamic characteristics of the optimized permanent magnet actuator model are analyzed by coupled finite element method. A displacement of plunger, flowing current of the coil, force of plunger, and velocity of plunger of the optimized permanent magnet actuator model are compared with the results of a primary permanent magnet actuator model.

Permanent Transvenous Endocardial Pacemaker Inevitably Implanted Two Electrode Leads (두개의 전극도자를 사용하게 된 Permanent Transvenous Pacemaker Implantation: 1례 보고)

  • Kwack, Moon-Sub;Lee, Hong-Kyun
    • Journal of Chest Surgery
    • /
    • v.14 no.2
    • /
    • pp.168-174
    • /
    • 1981
  • Since cardiac pacemaker was first totally implanted by Chardack, Gage and Greatbatch [1966], the electrical circuity of the cardiac pacemaker has been improved, modified, and refined. The problem of transvenous electrodes, however, is still remained; this may be due to electrode displacement, exit and/or entrance block, lead fracture and insulation defects. In permanent cardiac pacing, Irreversible loss of function of the transvenous electrode catheter eventually requires insertion of new lead. Authors now report one case that disclosed easy displacement of electrode tip in early phase of implantation and then two years and five months later, malfunctioning electrode could not be withdrawn from the cardiovascular system because it has become firmly enclosed by fibrous tissue along its course from the vein tract to the right ventricle. Under such circumstances, the electrode catheter tip was left in tricuspid annulus after being sutured at its entrance and burying the loop of lead in generator pocket. New other one electrode was then reimplantation through left external jugular vein.

  • PDF

The numerical study of seismic behavior of gravity retaining wall built near rock face

  • Taravati, Hossein;Ardakani, Alireza
    • Earthquakes and Structures
    • /
    • v.14 no.2
    • /
    • pp.179-186
    • /
    • 2018
  • We present the accurate investigation the seismic behavior of the gravity retaining wall built near rock face based on numerical method. The retaining wall is a useful structure in geotechnical engineering, where the earthquake is a common phenomenon; therefore, the evaluation of the behavior of the retaining wall during an earthquake is essential. However, in all previous studies, the backfill behind the wall was usually approximated by a homogeneous region, while in contrast, in practice, in many cases retaining walls are used to support the soil pressure in, inhomogeneous, mountainous area. This suggests an accurate investigation of the problem, i.e., numerical analysis. The numerical results will be compared with some of recently proposed analytical methods to show the accuracy of the proposed method. We show that increasing the volume of the rock face yields decreasing the permanent horizontal displacement of the gravity retaining wall built near rock face. Besides, we see that the permanent horizontal displacement of the gravity retaining wall with homogenous backfill is more than permanent horizontal displacement of the gravity retaining wall case of the built near rock face in different frequency contents.

Seismic response of operational tunnels to earthquakes with foreshocks or aftershocks

  • Junyoung Lee;Jae-Kwang Ahn;Byungmin Kim
    • Geomechanics and Engineering
    • /
    • v.38 no.6
    • /
    • pp.621-631
    • /
    • 2024
  • In designing earthquake-resistant structures, we traditionally select dynamic loads based on the recurrence period of earthquakes, using individual seismic records or aligning them with the design spectrum. However, these records often represent isolated waveforms lacking continuity, underscoring the need for a deeper understanding of natural seismic phenomena. The Earth's crustal movement, both before and after a significant earthquake, can trigger a series of both minor and major seismic events. These minor earthquakes, which often occur in short time before or after the major seismic events, prompt a critical reassessment of their potential impact on structural design. In this study, we conducted a detailed tunnel response analysis to assess the impact of both single mainshock and multiple earthquake scenarios (including foreshock-mainshock and mainshock-aftershock sequences). Utilizing numerical analysis, we explored how multiple earthquakes affect tunnel deformation. Our findings reveal that sequential seismic events, even those of moderate magnitude, can exert considerable stress on tunnel lining, resulting in heightened bending stress and permanent displacement. This research highlights a significant insight: current seismic design methodologies, which predominantly focus on the largest seismic intensity, may fail to account for the cumulative impact of smaller, yet frequent, seismic events like foreshocks and aftershocks. Our results demonstrate that dynamic analyses considering only a single mainshock are likely to underestimate the potential damage (i.e., ovaling deformation, failure lining, permanent displacement etc.) when compared to analyses that incorporate multiple earthquake scenarios.

Using a feed forward ANN to model the inelastic behaviour of confined sandwich panels

  • Marante, Maria E.;Barreto, Wilmer J.;Picon, Ricardo A.
    • Structural Engineering and Mechanics
    • /
    • v.71 no.5
    • /
    • pp.545-552
    • /
    • 2019
  • The analysis and design of complex structures like sandwich-panel elements are difficult; the use of finite element method for the analysis is complicated and time consuming when non-linear effects are considered. On the other hand, artificial neural network (ANN) models can capture the non-linear effects and its application requires lesser computational demand. Two ANN models were trained, tested and validated to compute the force for a given displacement of a sandwich-type roof element; 2555 force and element deformation pairs were used for training the ANN models. For the models trained without considering the damping effect, there were two values in the input layer: maximum displacement and current displacement, and for the model considering damping, displacement from the previous step was used as an additional input. Totally, 400 ANN models were trained. Results show that there is a good agreement between the experimental and simulated data, and the models showed a good performance with a mean square error value of 4548.85. Both the ANN models could simulate the inelastic behaviour, loss of rigidity, and evolution of permanent displacements. The models could also interpolate and extrapolate, which enables them to be used as an analysis and design tool for such complex elements.

Time-Series Interferometric Synthetic Aperture Radar Based on Permanent Scatterers Used to Analyze Ground Stability Near a Deep Underground Expressway Under Construction in Busan, South Korea (고정산란체 기반 시계열 영상레이더 간섭기법을 활용한 부산 대심도 지하 고속화도로 건설 구간의 지반 안정성 분석)

  • Taewook Kim;Hyangsun Han;Siung Lee;Woo-Seok Kim
    • The Journal of Engineering Geology
    • /
    • v.33 no.4
    • /
    • pp.689-699
    • /
    • 2023
  • Assessing ground stability is critical to the construction of underground transportation infrastructure. Surface displacement is a key indicator of ground stability, and can be measured using interferometric synthetic aperture radar (InSAR). This study measured time-series surface displacement using permanent scatterer InSAR applied to Sentinel-1 SAR images acquired from January 2017 to June 2023 for the area around a deep underground expressway under construction to connect Mandeok-dong and Centum City in Busan, South Korea. Regions of seasonal subsidence and uplift were identified, as were regions with severe subsidence after summer 2022. To evaluate stability of the ground in the construction area, the mean displacement velocity, final surface displacement, cumulative surface displacement, and difference between minimum and maximum surface displacement were analyzed. Considering the time-series surface displacement characteristics of the study area, the difference between minimum and maximum surface displacement since June 2022 was found to be the most suitable parameter for evaluating ground stability. The results identified highly unstable ground in the construction area as being to the north of the mid-lower reaches of the Oncheon-cheon River and to the west of the Suyeong River at the point where both rivers meet, with the difference between minimum and maximum surface displacement of 40~60 mm.

OBSERVATION OF SUBSIDENCE AT SHINHO INDUSTRIAL COMPLEX USING PERMANENT SCATTERERS

  • Kim, Sang-Wan;Won, Joong-Sun
    • Proceedings of the KSRS Conference
    • /
    • 2002.10a
    • /
    • pp.471-475
    • /
    • 2002
  • To detect ground subsidence, the permanent scatterer SAR interferometry is applied to the Shinho industrial complex. Eleven JERS-1 images were acquired in the study area between October 1996 and September 1998. All SAR data were co-registered to one master scene (January 8, 1998) and thus 10 interferograms were obtained in a time series. In order to determine permanent scatterers, coherence maps as well as the interferograms were generated and exploited. The coherence at the selected PSs was larger than 0.4 in a 515 sub-window and 0.5 in a 39 sub-window. Twenty-nine PSs within the reclaimed land and 8 PSs (as reference phase) outside the plant were selected for the analysis. The 29 PSs were grouped into 5 sub-groups. We removed the reference phase, which was estimated from 8 outside PSs that were considered as phases free of displacement, from the phases at PSs inside the plant. Residual phases could be interpreted as surface displacement and DEM error. The subsidence of about 40 cm was detected at group 4, while surface displacements were negligible in the rest groups.

  • PDF

A Basic Study of Displacement Measurement of Magnetic Bearing System Using Hall Effect Sensor (자기베어링 시스템에서의 변위측정을 위한 홀 효과 센서의 기초 연구)

  • Yang, J.H.;Jeong, G.G.;Jeong, H.H.;Son, S.K.
    • Journal of Power System Engineering
    • /
    • v.11 no.2
    • /
    • pp.72-76
    • /
    • 2007
  • Since the magnetic bearing system has unstability inherently it is necessary to measure the displacement for stable operation. Normally the displacement measurement is implemented by using sensors. The sensor for the displacement measurement is selected by precision, installation space, effect of magnetic field and response speed. And the cost of displacement measurement sensor also is considered. At the cost the hall effect sensor has a large advantage comparing with the others. Therefore this study concern about the basis experimental test for the displacement measurement of the magnetic bearing system that uses the hall effect sensor coupled with a tiny permanent magnet. The experimental results confirm the validity and practicability for this displacement measurement sensor.

  • PDF

ERUPTION GUIDANCE OF DISPLACED PERMANENT SUCCESSOR CAUSED BY PERIAPICAL LESION OF MANDIBULAR PRIMARY MOLAR (하악 유구치 치근단 병소에 의해 변위된 계승 영구치의 맹출유도)

  • Lim, Su-Min;Baik, Byeoug-Ju;Yang, Yeon-Mi;Han, Ji-Hye;Kim, Jae-Gon
    • Journal of the korean academy of Pediatric Dentistry
    • /
    • v.34 no.2
    • /
    • pp.335-340
    • /
    • 2007
  • Primary teeth and the permanent successor must be understood as interdependent units, where each one of them interacts with and depends upon the other. The spread of pulpal inflammation in primary teeth to the periradicular tissues can lead to early eruption, enamel hypoplasia or hypocalcification, developmental arrest of permanent successor. Also the periapical inflammation cause permanent tooth displacement in various direction. We describe here two clinical cases of displaced permanent successor caused by periapical lesion of mandibular primary molar in children.

  • PDF