• Title/Summary/Keyword: Partial Field

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An Acoustical Analysis on the Transformer Enclosure in Power Plants (발전소 변압기 밀폐구조의 음향해석)

  • 이준신;김연환;손석만
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 1997.10a
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    • pp.244-249
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    • 1997
  • The enclosure with a small opened area is extensively used in power plants to reduce the propagating noise from transformers. The radiation impedance associated with the location and width of the opened area, and the geometric configurations of internal acoustic field is very important to determine the basic acoustic characteristics of this partial enclosure. In this study, two-dimensional rectangular chambers with opened areas are investigated to examine the acoustic properties of the enclosure. The mode expansions of the physical variables defined on boundary surfaces are introduced to derive a simple algebraic equation. The acoustic characteristics can be easily predicted by this analytical approach, and the results well agree with physical grounds. Physical concepts as results of this work will be helpful to use the partial enclosure as a noise control element.

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Antitumor Activities by lmmunological Function of Chitin, Chitosan and Their Oligosaccharides (키틴 ${\cdot}$키토산 및 그 올리고당의 면역작용에 의한 항종양 활성)

  • 전유진;김세권
    • Journal of Life Science
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    • v.7 no.2
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    • pp.149-159
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    • 1997
  • Chitin, a linked polysaccharide composed of 2-acetamido-2-deoxy-$\beta$-D-glucopytanose residues, is distributed widely in nature. It has been utilized on various application field due to the development of chitin derivatives such as chitosan, partial deacetylated chitin, carboxylmethyl chitin, sulfated chitin, and so on. Chitin and chitosan have been recently interested in antitumor and antimicrobial activities, because of a powerful tumor inhibitory effect against experimental mouse tumors. Especially, the oligosaccharides obtained by partial degradation of them exhibited a remarkable antitumor effect against sarcoma 180, MM 48 and Meth Asolid tumors and antimetastatic effect against Lewis lung carcinoma in mice. This review describes on antitumor effects of chitin, chitosan and their oligosaccharides by their mechanism of action involving enhancement of immunological system.

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A review of effects of partial dynamic loading on dynamic response of nonlocal functionally graded material beams

  • Ahmed, Ridha A.;Fenjan, Raad M.;Hamad, Luay Badr;Faleh, Nadhim M.
    • Advances in materials Research
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    • v.9 no.1
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    • pp.33-48
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    • 2020
  • With the use of differential quadrature method (DQM), forced vibrations and resonance frequency analysis of functionally graded (FG) nano-size beams rested on elastic substrate have been studied utilizing a shear deformation refined beam theory which contains shear deformations influence needless of any correction coefficient. The nano-size beam is exposed to uniformly-type dynamical loads having partial length. The two parameters elastic substrate is consist of linear springs as well as shear coefficient. Gradation of each material property for nano-size beam has been defined in the context of Mori-Tanaka scheme. Governing equations for embedded refined FG nano-size beams exposed to dynamical load have been achieved by utilizing Eringen's nonlocal differential law and Hamilton's rule. Derived equations have solved via DQM based on simply supported-simply supported edge condition. It will be shown that forced vibrations properties and resonance frequency of embedded FG nano-size beam are prominently affected by material gradation, nonlocal field, substrate coefficients and load factors.

Conformable solution of fractional vibration problem of plate subjected to in-plane loads

  • Fadodun, Odunayo O.;Malomo, Babafemi O.;Layeni, Olawanle P.;Akinola, Adegbola P.
    • Wind and Structures
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    • v.28 no.6
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    • pp.347-354
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    • 2019
  • This study provides an approximate analytical solution to the fractional vibration problem of thin plate governing anomalous motion of plate subjected to in-plane loads. The method of variable separable is employed to transform the fractional partial differential equations under consideration into a fractional ordinary differential equation in temporal variable and a bi-harmonic plate equation in spatial variable. The technique of conformable fractional derivative is utilized to solve the resulting fractional differential equation and the approach of finite sine integral transform method is used to solve the accompanying bi-harmonic plate equation. The deflection field which measures the transverse displacement of the plate is expressed in terms of product of Bessel and trigonometric functions via the temporal and spatial variables respectively. The obtained solution reduces to the solution of the free vibration problem of thin plate in literature. This work shows that conformable fractional derivative is an efficient mathematical tool for tracking analytical solution of fractional partial differential equation governing anomalous vibration of thin plates.

Bearing faults localization of a moving vehicle by using a moving frame acoustic holography (이동 프레임 음향 홀로그래피를 이용한 주행 중인 차량의 베어링 결함 위치 추정)

  • Jeon, Jong-Hoon;Park, Choon-Su;Kim, Yang-Hann;Koh, Hyo-In;You, Won-Hee
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2009.04a
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    • pp.681-688
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    • 2009
  • This paper deals with a bearing faults localization technique based on holographic approach by visualizing sound radiated from the faults. The main idea stems from the phenomenon that bearing faults in a moving vehicle generate impulsive sound. To visualize fault signal from the moving vehicle, we can use the moving frame acoustic holography [H.-S. Kwon and Y.-H. Kim, "Moving frame technique for planar acoustic holography," J. Acoust. Soc. Am. 103(4), 1734-1741, 1998]. However, it is not easy to localize faults only by applying the method. This is because the microphone array measures noise (for example, noise from other parts of the vehicle and the wind noise) as well as the fault signal while the vehicle passes by the array. To reduce the effect of noise, we propose two ideas which utilize the characteristics of fault signal. The first one is to average holograms for several frequencies to reduce the random noise. The second one is to apply the partial field decomposition algorithm [K.-U. Nam, Y.-H. Kim, "A partial field decomposition algorithm and its examples for near-field acoustic holography," J. of Acoust. Soc. Am. 116(1), 172-185, 2004] to the moving source, which can separate the fault signal and noise. Basic theory of those methods is introduced and how they can be applied to localize bearing faults is demonstrated. Experimental results via a miniature vehicle showed how well the proposed method finds out the location of source in practice.

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Axisymmetric Swirling Flow Simulation of the Draft Tube Vortex in Francis Turbines at Partial Discharge

  • Susan-Resiga, Romeo;Muntean, Sebastian;Stein, Peter;Avellan, Francois
    • International Journal of Fluid Machinery and Systems
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    • v.2 no.4
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    • pp.295-302
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    • 2009
  • The flow in the draft tube cone of Francis turbines operated at partial discharge is a complex hydrodynamic phenomenon where an incoming steady axisymmetric swirling flow evolves into a three-dimensional unsteady flow field with precessing helical vortex (also called vortex rope) and associated pressure fluctuations. The paper addresses the following fundamental question: is it possible to compute the circumferentially averaged flow field induced by the precessing vortex rope by using an axisymmetric turbulent swirling flow model? In other words, instead of averaging the measured or computed 3D velocity and pressure fields we would like to solve directly the circumferentially averaged governing equations. As a result, one could use a 2D axi-symmetric model instead of the full 3D flow simulation, with huge savings in both computing time and resources. In order to answer this question we first compute the axisymmetric turbulent swirling flow using available solvers by introducing a stagnant region model (SRM), essentially enforcing a unidirectional circumferentially averaged meridian flow as suggested by the experimental data. Numerical results obtained with both models are compared against measured axial and circumferential velocity profiles, as well as for the vortex rope location. Although the circumferentially averaged flow field cannot capture the unsteadiness of the 3D flow, it can be reliably used for further stability analysis, as well as for assessing and optimizing various techniques to stabilize the swirling flow. In particular, the methodology presented and validated in this paper is particularly useful in optimizing the blade design in order to reduce the stagnant region extent, thus mitigating the vortex rope and expending the operating range for Francis turbines.

Evaluation on Nutritional Value of Field Crickets as a Poultry Feedstuff

  • Wang, Dun;Zhai, Shao Wei;Zhang, Chuan Xi;Bai, Yao Yu;An, Shi Heng;Xu, Ying Nan
    • Asian-Australasian Journal of Animal Sciences
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    • v.18 no.5
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    • pp.667-670
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    • 2005
  • The proximate analysis, amino acid content and true amino acid digestibility and TMEn for poultry of adult Field crickets Gryllus testaceus Walker, were investigated. The insect was also used as partial replacement of protein supplements in the broiler diet on an equal CP percentage and TMEn basis. The results indicated that the adult insect contained: crude protein 58.3%; fat 10.3%, chitin 8.7% and ash 2.96% on dry matter basis, respectively. The total amounts of methionine, cystine and lysine in the Field crickets were 1.93%, 1.01% and 4.79%, respectively, and their true digestibility coefficients, determined in cecectomized roosters, were 94.1%, 85% and 96%, respectively. The TMEn of this insect meal was 2,960 kcal/kg determined in cecectomized roosters. When cornsoybean meal diets were formulated on an equal CP percentage and TMEn basis, up to 15% Field cricket could replace control diet without any adverse affects on broiler weight gain, feed intake or gain:feed ratio from 8 to 20 d posthatching.

Effect of Metallic Particles on E-field Enhancement in Extra High Voltage Gas-insulated Transmission Lines

  • Rao, M. Mohana;Satyanarayana, S.;Kumar, S. Vinay;Jain, H.S.
    • Journal of Electrical Engineering and Technology
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    • v.5 no.4
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    • pp.631-636
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    • 2010
  • Gas-insulated transmission lines (GITL) are valued as technological solutions in hydro-power stations due to their enormous power handling capabilities. The performance of GITL is a function of the size of metallic particles inside the gas-insulated chamber. Electrostatic field (E-field) enhancement is a common phenomenon in gas-insulated lines due to these metallic particles. In this study, the E-field enhancement factor is calculated by considering metallic particles at various locations in the gas-insulated line/bus section, such as high-tension (HT) conductor, high-voltage shields, support insulator, and inner surface of grounded enclosure. For this purpose, a two-dimensional model based on finite element (FE) method is developed. The length of the metallic particle is in the range of 1 to 10 mm while the diameter is between 1 to 3 mm. E-field enhancement is also computed for various particle configurations of the gas-insulated system, with focus on dielectric coating made of epoxy on HT conductor and inner surface of grounded enclosure.

Study on the Tx/Rx Beam Performance of Planar Active Phased Array Antenna for Airborne as using the Near-field Measurement (근접전계 시험을 이용한 항공기용 평면형 능동 위상 배열 안테나 송수신 빔 성능 검증에 관한 연구)

  • Kim, Young-Wan;Lee, Jaemin;Lee, Yuri;Kim, JongPhil;Park, Jong-Kuk;Park, Kyuchul;Kim, Sunju
    • Journal of the Korea Institute of Military Science and Technology
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    • v.21 no.1
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    • pp.61-68
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    • 2018
  • In this paper, we described about methods and results to verify the Tx/Rx beam characteristics of a planar active phased array antenna as using a near-field measurement. The near-field system can effectively measure multiple beams and predict the performance degradation due to the partial failure of individual elements. Also, it can accurately predict the EIRP relating to detection performance of the active phased array radar. We briefly described the near-field measurement method to verify the Tx/Rx beam characteristics, and then verified the effectiveness of measurement method by analyzing the measured results.

Comparison of internal adaptation of removable partial denture metal frameworks made by lost wax technique and printing technique of pattern using CAD (Lost wax technique과 CAD를 이용한 pattern의 프린팅 방식으로 제작된 가철성 국소의치 금속구조물의 적합도 비교)

  • Choi, Wonjun;Woo, Yi-Hyung;Kim, Hyeong-Seob;Paek, Janghyun
    • The Journal of Korean Academy of Prosthodontics
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    • v.56 no.1
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    • pp.17-24
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    • 2018
  • Lost wax technique of casting wax patterns has been used principally to make metal frameworks of removable partial dentures. Since the development of digital technology and CAD, metal frameworks can be built through digital surveying and framework designing. Many cases proved that resin patterns made by CAD printing method were well adapted to internal oral structure and final metal frameworks also showed good internal adaptation as well. The metal frameworks of a removable partial denture were made by both lost wax technique and CAD technique and were applied to a patient with severe alveolar bone loss. Using CAD data and fit checker, internal adaptation of both metal frameworks were evaluated by comparing the gap between surveyed crown and its structure. This study is to prove that metal frameworks by both techniques showed adaptation that can be applied in clinical field.