• Title, Summary, Keyword: full scale measurements

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A neural network shelter model for small wind turbine siting near single obstacles

  • Brunskill, Andrew William;Lubitz, William David
    • Wind and Structures
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    • v.15 no.1
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    • pp.43-64
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    • 2012
  • Many potential small wind turbine locations are near obstacles such as buildings and shelterbelts, which can have a significant, detrimental effect on the local wind climate. A neural network-based model has been developed which predicts mean wind speed and turbulence intensity at points in an obstacle's region of influence, relative to unsheltered conditions. The neural network was trained using measurements collected in the wakes of 18 scale building models exposed to a simulated rural atmospheric boundary layer in a wind tunnel. The model obstacles covered a range of heights, widths, depths, and roof pitches typical of rural buildings. A field experiment was conducted using three unique full scale obstacles to validate model predictions and wind tunnel measurements. The accuracy of the neural network model varies with the quantity predicted and position in the obstacle wake. In general, predictions of mean velocity deficit in the far wake region are most accurate. The overall estimated mean uncertainties associated with model predictions of normalized mean wind speed and turbulence intensity are 4.9% and 12.8%, respectively.

Evaluation of buffeting response predictions of a cable-stayed bridge from full-scale measurements during a typhoon (실교량 계측을 통한 태풍 영양하의 사장교 버페팅 응답 평가)

  • Park, Jin;Kim, Ho-Kyung;Cho, Soo-Jin;Kim, Gi-Nam;Park, Jun-Yong;Seo, Ju-Won
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.82-83
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    • 2011
  • 본 논문에서는 3경간 연속 사장교에 설치 된 계측장비에서 2010년 태풍 곤파스 당시 계측한 바람 및 교량응답 자료를 바탕으로 사장교의 버페팅 응답을 평가하였다. 계측 된 바람자료에서 스펙트럼 분석을 수행하고 그 결과를 버페팅 해석에 반영하여 실교량 거동을 예측하였다. 예측 된 교량의 거동은 실제 계측 된 값과 유산한 결과를 나타내었다.

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Development of a Dynamically Scaled Model of the Catenary for High Speed Railway (고속전철 가선계의 축소모델 개발에 관한 연구)

  • Kim, Jung-Soo
    • Journal of the Korean Society for Railway
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    • v.10 no.4
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    • pp.409-413
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    • 2007
  • A dynamically scaled model of the catenary with a nominal scaling factor of 18.5:1 is designed and constructed. The motivation for developing such a model is the great difficulty of making accurate measurements on the full-scale catenary and the difficulty of making experimental modifications to it. The scaled model is designed to be dynamically equivalent to the full scale catenary with respect to the mass and elastic strength. The scaled model is partially verified by comparing linear vibration and wave characteristics with those predicted by the simulation study.

A 6 m cube in an atmospheric boundary layer flow -Part 2. Computational solutions

  • Richards, P.J.;Quinn, A.D.;Parker, S.
    • Wind and Structures
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    • v.5 no.2_3_4
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    • pp.177-192
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    • 2002
  • Computation solutions for the flow around a cube, which were generated as part of the Computational Wind Engineering 2000 Conference Competition, are compared with full-scale measurements. The three solutions shown all use the RANS approach to predict mean flow fields. The major differences appear to be related to the use of the standard $k-{\varepsilon}$, the MMK $k-{\varepsilon}$ and the RNG $k-{\varepsilon}$ turbulence models. The inlet conditions chosen by the three modellers illustrate one of the dilemmas faced in computational wind engineering. While all modeller matched the inlet velocity profile to the full-scale profile, only one of the modellers chose to match the full-scale turbulence data. This approach led to a boundary layer that was not in equilibrium. The approach taken by the other modeller was to specify lower inlet turbulent kinetic energy level, which are more consistent with the turbulence models chosen and lead to a homogeneous boundary layer. For the $0^{\circ}$ case, wind normal to one face of the cube, it is shown that the RNG solution is closest to the full-scale data. This result appears to be associated with the RNG solution showing the correct flow separation and reattachment on the roof. The other solutions show either excessive separation (MMK) or no separation at all (K-E). For the $45^{\circ}$ case the three solutions are fairly similar. None of them correctly predicting the high suctions along the windward edges of the roof. In general the velocity components are more accurately predicted than the pressures. However in all cases the turbulence levels are poorly matched, with all of the solutions failing to match the high turbulence levels measured around the edges of separated flows. Although all of the computational solutions have deficiencies, the variability of results is shown to be similar to that which has been obtained with a similar comparative wind tunnel study. This suggests that the computational solutions are only slightly less reliable than the wind tunnel.

Field measurements of wind pressure on an open roof during Typhoons HaiKui and SuLi

  • Feng, Ruoqiang;Liu, Fengcheng;Cai, Qi;Yan, Guirong;Leng, Jiabing
    • Wind and Structures
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    • v.26 no.1
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    • pp.11-24
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    • 2018
  • Full-scale measurements of wind action on the open roof structure of the WuXi grand theater, which is composed of eight large-span free-form leaf-shaped space trusses with the largest span of 76.79 m, were conducted during the passage of Typhoons HaiKui and SuLi. The wind pressure field data were continuously and simultaneously monitored using a wind pressure monitoring system installed on the roof structure during the typhoons. A detailed analysis of the field data was performed to investigate the characteristics of the fluctuating wind pressure on the open roof, such as the wind pressure spectrum, spatial correlation coefficients, peak wind pressures and non-Gaussian wind pressure characteristics, under typhoon conditions. Three classical methods were used to calculate the peak factors of the wind pressure on the open roof, and the suggested design method and peak factors were given. The non-Gaussianity of the wind pressure was discussed in terms of the third and fourth statistical moments of the measured wind pressure, and the corresponding indication of the non-Gaussianity on the open roof was proposed. The result shows that there were large pulses in the time-histories of the measured wind pressure on Roof A2 in the field. The spatial correlation of the wind pressures on roof A2 between the upper surface and lower surface is very weak. When the skewness is larger than 0.3 and the kurtosis is larger than 3.7, the wind pressure time series on roof A2 can be taken as a non-Gaussian distribution, and the other series can be taken as a Gaussian distribution.

Advancing behavioral understanding and damage evaluation of concrete members using high-resolution digital image correlation data

  • Sokoli, Drit;Shekarchi, William;Buenrostro, Eliud;Ghannoum, Wassim M.
    • Earthquakes and Structures
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    • v.7 no.5
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    • pp.609-626
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    • 2014
  • The capabilities of a high-resolution Digital Image Correlation (DIC) system are presented within the context of deformation measurements of full-scale concrete columns tested under reversed cyclic loading. The system was developed to have very high-resolution such that material strains on the order of the cracking stain of concrete could be measured on the surface of full-scale structural members. The high-resolution DIC system allows the measurement of a wide range of deformations and strains that could only be inferred or assumed previously. The DIC system is able to resolve the full profiles of member curvatures, rotations, plasticity spread, shear deformations, and bar-slip induced rotations. The system allows for automatic and objective measurement of crack widths and other damage indices that are indicative of cumulated damage and required repair time and cost. DIC damage measures contrast prevailing proxy damage indices based on member force-deformation data and subjective damage measures obtained using visual inspection. Data derived from high-resolution DIC systems is shown to be of great use in advancing the state of behavioral knowledge, calibrating behavioral and analytical models, and improving simulation accuracy.

Measurement Uncertainty Analysis for Fluctuating Hull Pressure (선미변동압력 계측시험에서의 불확실성 해석)

  • G.I. Choi
    • Journal of the Society of Naval Architects of Korea
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    • v.30 no.4
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    • pp.46-60
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    • 1993
  • Accurate measurements of fluctuating pressure in the cavitation tunnel are necessary to predict vibration and noise intensities in full scale ship. In this paper, the results of an experimental study on fluctuating pressure induced by a cavitating propeller are presented and discussed. Extensive measurements at several propeller revolutions are made using the flat plate to understand controversial problems of the effects of propeller revolution in the cavitation tunnel. The analysis of the uncertainties in experimental measurements and results is used to estimate the errors in uniform flow.

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Monitoring of tall slender structures by GPS measurements

  • Chmielewski, Tadeusz;Breuer, Peter;Gorski, Piotr;Konopka, Eduard
    • Wind and Structures
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    • v.12 no.5
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    • pp.401-412
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    • 2009
  • A method is applied for the estimation of structural damage of tall slender structures using natural frequency and displacements measurements by GPS. The relationship between the variation in the global stiffness matrix (or in the stiffness of each finite element) and the change in the natural frequencies of the structure is given. In engineering practice the number of frequencies which can be derived by GPS measurement of long-period structures will be equal to one, two or three first natural frequencies. This allows us in initial studies to detect damage with frequency changes based on forward methods in which the measured frequencies are compared with the predicted analytical data. This idea, of health monitoring from possible changes to natural frequencies, or from a statement of excessive displacements is applied to the Stuttgart TV Tower.

The Effect of Phytofiltration System on the Improvement of Indoor Air Quality (식물을 이용한 실내공기환경 정화효과에 관한 연구)

  • Song, Jeong-Eun;Pang, Seung-Ki;Kim, Yong-Sik;Sohn, Jang-Yeul
    • KIEAE Journal
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    • v.5 no.4
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    • pp.3-8
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    • 2005
  • The objective of this study is to examine the impact of the Phytofiltration system on the improvement of indoor air quality. Measurement was performed in a full-scale mock up model to examine the purification efficiency of air by plants. Seven species of plants, which were recommended by NASA, were used in measurements. Two species of plants that showed outstanding purifying effects were chosen for further measurements. The measurements were performed according to the positions and amounts of plants. Thermal environment, the concentration of Toluene and Formaldehyde were monitored. Ficus Benjamiana and Aglaonema brevispathum were excellent in diluting the concentration of contaminants. The effect of diluting concentration became better as the amount of plants increased. The reducing effect was the best when the plants were placed near window.

Displacement prediction of precast concrete under vibration using artificial neural networks

  • Aktas, Gultekin;Ozerdem, Mehmet Sirac
    • Structural Engineering and Mechanics
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    • v.74 no.4
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    • pp.559-565
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    • 2020
  • This paper intends to progress models to accurately estimate the behavior of fresh concrete under vibration using artificial neural networks (ANNs). To this end, behavior of a full scale precast concrete mold was investigated numerically. Experimental study was carried out under vibration with the use of a computer-based data acquisition system. In this study measurements were taken at three points using two vibrators. Transducers were used to measure time-dependent lateral displacements at these points on mold while both mold is empty and full of fresh concrete. Modeling of empty and full mold was made using ANNs. Benefiting ANNs used in this study for modeling fresh concrete, mold design can be performed. For the modeling of ANNs: Experimental data were divided randomly into two parts such as training set and testing set. Training set was used for ANN's learning stage. And the remaining part was used for testing the ANNs. Finally, ANN modeling was compared with measured data. The comparisons show that the experimental data and ANN results are compatible.