• Title/Summary/Keyword: beating

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Beating phenomena in spacecraft sine testing and an attempt to include the sine sweep rate effect in the test-prediction

  • Nali, Pietro;Bettacchioli, Alain
    • Advances in aircraft and spacecraft science
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    • v.3 no.2
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    • pp.197-209
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    • 2016
  • The Spacecraft (S/C) numerical sine test-predictions are usually performed through Finite Element Method (FEM) Frequency Response Analysis (FRA), that is the hypothesis of steady-state responses to harmonic excitation to the S/C base is made. In the test practice, the responses are transient and may be significantly different from those predicted through FRA. One of the most significant causes of discrepancy between prediction and test consists in the beating phenomena. After a brief overview of the topic, the typical causes of beating are described in the first part of the paper. Subsequently, focus is made on the sine sweep rate effect, which often leads to have beatings after the resonance of weakly damped modes. In this work, the approach illustrated in the literature for calculating the sine sweep rate effect in the case of Single-Degree-Of-Freedom (SDOF) oscillators is extended to Multi-Degrees-Of-Freedom (MDOF) systems, with the aim of increasing the accuracy of the numerical sine test-predictions. Assumptions and limitations of the proposed methodology are detailed along the paper. Several assessments with test results are discussed and commented.

Study on Reduction of Excessive Noise and Vibration of Aft Part of High Speed Ro-Ro Passenger Ship (고속 여객선 선미부 과대 진동/소음 감소를 위한 연구)

  • Shin, Yunkil
    • Journal of Ocean Engineering and Technology
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    • v.33 no.2
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    • pp.196-202
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    • 2019
  • In this study, the excessive noise and vibration phenomena of a high-speed Ro/Ro passenger ship were analyzed, and a countermeasure was taken based on them. This ship was granted a comfort class notation by the classification society, which was COMFORT-VIBRATION-II and COMFORT-NOISE-CREW-II. However, unfortunately, excessive noise and vibration in the aft part of the ship were delivered from the twin shaft propellers, and therefore the Class Requirement was not satisfied before delivery. In order to obtain the class notation, all of the concerned parties came to an agreement to reduce the noise and vibration level during operation after delivery because a seasonal ferry service was already scheduled and the cabin was fully booked. The root cause of the massive amount of noise and vibration was mainly the propeller-induced excitation pulse and beating that occurred from the mismatch of the rotating speeds of the two shaft lines. A 1st order vibrating force and beating phenomena existed in the propeller. Thus, a reduction of the excitation force, elimination of the beating phenomena, and decrease of the noise level at the aft area cabins and public spaces were required. In addition, structural reinforcements were conducted using pillars and additional girders at the aft part of the decks.

Effects of Guaruhaebaekbanha-tang Extract on Beating Rate and LDH Activity in Cultured Rat Myocardial Cells (과루해백반하탕 추출물이 배양 심근세포의 박동수와 LDH 활성도에 미치는 영향)

  • An Hyo Chang;Kwon Kang Beam;Park Eun Young;Jang Seung Ho;Ryu Do Gon
    • Journal of Physiology & Pathology in Korean Medicine
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    • v.16 no.2
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    • pp.289-295
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    • 2002
  • To certify the protective effect of herbal medicine against oxygen free radical-induced myocardiotoxicity, cytotoxicity was measured using MTT, LDH activity and Beating rate assay in the presence of Guaruhaebaekbanha-tang(GHBT) extracts or single constituents of this prescription. Myocardial toxicity was evaluated in neonatal rat myocardiocytes in cultures. In the present study, xanthine oxidase/hypoxanthine(XO/HX) resulted in a decrease in cell viability, increases in LDH activity in culture medium and decreases in beating rate in cultured myocardial cells. In the effect of GHBT extract, it showed the prevention from the XO/HX-induced cardiotoxicity by the increases of cell viability and beating rate as well as the decrease of LDH activity. In the protective effect of Fructus Trichosanthis(FT), Bulbus Allii Macrostemi(BAM) and Rhizoma Pinelliae(RP), all the extracts were significantly effective in the protection of XO/HX-induced cardiotoxocity in cultured myocardial cells by the increase of beating rate as well as th decrease of LDH activity. From these results, they show that XO/HX is cardiotoxic in cultured myocardial cells derived from neonatal rat, and it suggests that GHBT, FT, SAM, RP extracts are positively effective in the blocking in XO/HX-induced cardiotoxicity.

The beating effect of high crystalized nonwood fibers treated with low-molecular weighted waste celulase in the papermaking processes (Cellulase생산공정중 발생되는 저분자량 분포도의 폐효소류 처리가 고결정화된 배목재 섬유소의 고해에 미치는 영향)

  • 김병현;신종순;강영립;박병권;이성구
    • Journal of the Korean Graphic Arts Communication Society
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    • v.18 no.1
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    • pp.121-139
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    • 2000
  • This study is to test the possibility of applying the low-molecular weighted waste cellulase, which is produced in the process of cellulase production, to paper making. After experimenting on high-crystallized non-wood fibers with beating catalyst. I got the result that the condition for the optimal effect is temperature 40~6$0^{\circ}C$, the time 90min to 120min, pH 5.0 to 6.0, the enzyme contents 0.3% and that the effect of beating such as slight reduction of fiver viscosity, increase of water retention value(WRV) and shortening of fiber length was increased with waste cellulase. Through this process, the density, folding endurance, tensile strength and burst strength of paper was remarkably increased, which is inferred to result from the increased flexibility of fiber by individual characteristics of non-wood fiber, which was high-crystallized by penetrated low-molecular weight cellulases in the fiber.

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Effects of Fructus Schisandrae Water Extract on Cultured Mouse Myocardial Cells Induced by Xanthine Oxidase/Hypoxanthine (오미자 추출물이 산소지유기에 의하여 손상된 생쥐의 배양 심근세포에 미치는 영향)

  • 주은정
    • Journal of Nutrition and Health
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    • v.33 no.7
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    • pp.739-744
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    • 2000
  • The purpose of this study was to elucidate protective effect of Fructus Schsandrae(FS) water extract against xanthine oxidase/hypoxanthine(XO/HX)-induced cardiotoxicity in myocardial cells this experiment was performed. Cardiotoxicity of XO/HX was examined by MTT(MTT [3-(4,5-dimethylthiazol-2-yl)-2.5,-diphenyl tetrazolium bromide) assay. XO/HX induced the decrease of cell viability. Also XO/HX induced the increase of LDH activity and the decrease of beating rate on cultured myocardial cells in a dose-dependent manner. To investigate cardioprotective effect of FS water extract cultures were preincubated with FS water extract for 3 hours. Cultures were then exposed to XO/HX for 72 hours. FS water extract have an efficacy in decreaasing LDH activity and increasing heart beating rate on cultured myocardial cells damaged by XO/HX. From the results it is suggested that XO/HX may show toxic effect in cultured myocardial cells derived from neonatal mouse and FS water extract is effective in the prevention of XO/HX-induced cardiotoxicity.

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A Study on the Optimal Span Length Selection of Conventional Railway Bridges considering Resonance Suppression (공진소멸 현상을 이용한 기존선 철도교량의 지간 최적화를 위한 연구)

  • Kim Sungil;Chung Wonseok;Choi Eunsoo
    • Journal of the Korean Society for Railway
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    • v.8 no.2
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    • pp.137-144
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    • 2005
  • The possibility of resonance exists always in railway bridges unlike highway bridges because railway bridges are loaded repeatedly by specific trains which has equidistant wheel loads. Resonance phenomenon of the bridge can be broken out when exciting frequencies by tram determined from the speed and effective beating internal coincides with natural frequencies of the bridge Excessive fluctuations of dynamic displacements and accelerations by resonance cause unpleasant passenger comfort and instability of railway structures. On the other hand, resonance suppression phenomenon that all the previous loads which pass through the bridge sum to zero can be occurred. In case we apply this resonance suppression properly, design of stable railway bridge from dynamics point of view can be made. In the present study, most dominant beating internal of conventional trams will be find. A(ter that. specific span length of the bridge which derives resonance suppression can be selected for railway bridges which accomplishes superior dynamic behavior.

A Correlation between Emile Sound and Other Waves (에밀레의 맥놀이와 다른 파동과의 상관관계)

  • 안정근;진용옥
    • The Journal of the Acoustical Society of Korea
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    • v.20 no.1
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    • pp.30-35
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    • 2001
  • The most important characteristic of Emile Bell's sound is a beating. It is modulation phenomenon which appears as a result of interference multiplication in time domain. This modulation phenomenon can be modeled as DSB-SC which suppress carrier and signals distributed both sides. The beatiog wave is observed in Laman distribution signal for polyvinyl speech signal, water vein wave, tide wave. The beating wave is caused by asymmetry Property of the bell.

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Improvement of Physical Characteristics of Paper with Micro Pulp (마이크로 펄프를 이용한 종이의 물성 개선)

  • Kim, Hak-Sang;Kim, Bong-Yong
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • v.40 no.1
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    • pp.9-14
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    • 2008
  • Beating and using chemical agents are common methods to improve physical properties. But the beating is high energy consumption process and chemical agent addition may cause deteriorate waste water quality. Therefore, it is necessary to use more environment-friendly methods. In this study, micro pulp was used in the handsheet making to get improving effects of physical properties without beating treatment and chemicals. Stiffness, thickness and air permeability were increased and strength properties of paper were also improved to some extents by only the micro pulp addition.

Development of Observation Methods for Density of Stink Bugs in Soybean Field (콩포장에서 노린재류의 밀도조사법 개발)

  • Bae, Soon-Do;Kim, Hyun-Ju;Lee, Geon-Hwi;Park, Sung-Tae
    • Korean journal of applied entomology
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    • v.46 no.1 s.145
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    • pp.153-158
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    • 2007
  • This study was conducted to develope the observing methods for density of stink bugs in soybean reproductive stage. The adults and nymphs of bean bug, Riptortus clavatus, red-banded shield bug, Piezodous hybneri, green stink bug, Nezara antennata, Sole bug, Dolycoris baccarum, and brown marmorated stink bug, Halyomorpha halys were observed by three observing methods such as beating, sweeping net, and visual counting methods in the full bloom (R2), full pod (R4) and beginning maturity (R7) of soybean. As a result, total number of stink bugs observed was the highest with 5,214.2 by beating method, and then was 2,581.8 by visual counting method, and was the lowest with 103.1 by sweeping net method. Total number of stink bugs observed by the beating and visual counting methods was P. hybneri, followed by N. antennata, H. halys, R. clavatus and D. baccarum with clear difference in observed number of each stink bugs while total number of stink bugs observed by sweeping net method was very low in the range of 18 to 23. Accordingly, the observed density of stink bugs exception of R. clavatus adult by beating method was generally high. However, the number of R. clavatus adult was more observed by flushing method than that by beating method from the beginning bloom (R1) to full maturity (R8), and was more observed at morning time than that at afternoon time. Therefore, two observation methods that flushing method for R. clavatus and beating method for the other stink bugs were recommended for the occurring density of stink bugs in soybean because both bean bug and pentatomidae stink bugs have distinct behavior characteristics such as flying and dropping.

Case Studies on Beating Phenomena of Hydraulic Couplings (유체 커플링의 맥놀이 현상 사례 연구)

  • 최성필;박종포;김호종
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 1997.04a
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    • pp.133-138
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    • 1997
  • Belt-conveyer driving systems, which transport coal stored in the yard of a coal-fired fossil power plant to coal silos, experienced severe vibrations. From measurement, it was found that the vibrations showed beating phenomenoa and arose from hydraulic couplings installed between motors and gear boxes. In the present paper, described are results of case studies on vibration troubleshooting for the belt-conveyor driving systems: 1)resonance of the system; 2)field balancing.

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