The Experts below are selected from a list of 173592 Experts worldwide ranked by ideXlab platform
Chong-won Lee - One of the best experts on this subject based on the ideXlab platform.
-
In situ runout identification in active magnetic bearing system by extended Influence Coefficient method
IEEE ASME Transactions on Mechatronics, 1997Co-Authors: Cheol-soon Kim, Chong-won LeeAbstract:In this paper, an efficient, yet easy-to-use, in-situ runout identification scheme, based on the extended Influence Coefficient method, is presented for active magnetic bearing (AMB) systems. It is shown experimentally that the proposed scheme successfully identifies and eliminates the troublesome runout of a well-balanced AMB system in the laboratory, so that a high-precision spindle system can be achieved, while it is in operation.
John K Ramsey - One of the best experts on this subject based on the ideXlab platform.
-
comparison of theoretical and experimental unsteady aerodynamics of linear oscillating cascade with supersonic leading edge locus video
2004Co-Authors: John K Ramsey, Dan ErwinAbstract:An experimental Influence Coefficient technique was used to obtain unsteady aerodynamic Influence Coefficients and, consequently, unsteady pressures for a cascade of symmetric airfoils oscillating in pitch about mid-chord. Stagger angles of 0 deg and 10 deg were investigated for a cascade with a gap-to-chord ratio of 0.417 operating at an axial Mach number of 1.9, resulting in a supersonic leading-edge locus. Reduced frequencies ranged from 0.056 to 0.2. The Influence Coefficients obtained determine the unsteady pressures for any interblade phase angle. The unsteady pressures were compared with those predicted by several algorithms for interblade phase angles of 0 deg and 180 deg.
-
experimental unsteady pressures on an oscillating cascade with supersonic leading edge locus
17th Aerospace Ground Testing Conference, 1992Co-Authors: Daniel Erwin, G M Gregorek, John K RamseyAbstract:The first experimental data for an oscillating cascade with a supersonic leading edge locus (SLEL) at zero stagger angle is presented which were obtained in the NASA/OSU supersonic oscillating cascade facility. Reduced frequencies from .093 to .146, based on half chord were investigated. An Influence Coefficient technique for a linear oscillating cascade with constant interblade phase angle has been extended to a cascade with a SLEL.
Cheol-soon Kim - One of the best experts on this subject based on the ideXlab platform.
-
In situ runout identification in active magnetic bearing system by extended Influence Coefficient method
IEEE ASME Transactions on Mechatronics, 1997Co-Authors: Cheol-soon Kim, Chong-won LeeAbstract:In this paper, an efficient, yet easy-to-use, in-situ runout identification scheme, based on the extended Influence Coefficient method, is presented for active magnetic bearing (AMB) systems. It is shown experimentally that the proposed scheme successfully identifies and eliminates the troublesome runout of a well-balanced AMB system in the laboratory, so that a high-precision spindle system can be achieved, while it is in operation.
Jae Heon Cho - One of the best experts on this subject based on the ideXlab platform.
-
watershed model calibration framework developed using an Influence Coefficient algorithm and a genetic algorithm and analysis of pollutant discharge characteristics and load reduction in a tmdl planning area
Journal of Environmental Management, 2015Co-Authors: Jae Heon Cho, Jong Ho LeeAbstract:Manual calibration is common in rainfall-runoff model applications. However, rainfall-runoff models include several complicated parameters; thus, significant time and effort are required to manually calibrate the parameters individually and repeatedly. Automatic calibration has relative merit regarding time efficiency and objectivity but shortcomings regarding understanding indigenous processes in the basin. In this study, a watershed model calibration framework was developed using an Influence Coefficient algorithm and genetic algorithm (WMCIG) to automatically calibrate the distributed models. The optimization problem used to minimize the sum of squares of the normalized residuals of the observed and predicted values was solved using a genetic algorithm (GA). The final model parameters were determined from the iteration with the smallest sum of squares of the normalized residuals of all iterations. The WMCIG was applied to a Gomakwoncheon watershed located in an area that presents a total maximum daily load (TMDL) in Korea. The proportion of urbanized area in this watershed is low, and the diffuse pollution loads of nutrients such as phosphorus are greater than the point-source pollution loads because of the concentration of rainfall that occurs during the summer. The pollution discharges from the watershed were estimated for each land-use type, and the seasonal variations of the pollution loads were analyzed. Consecutive flow measurement gauges have not been installed in this area, and it is difficult to survey the flow and water quality in this area during the frequent heavy rainfall that occurs during the wet season. The Hydrological Simulation Program-Fortran (HSPF) model was used to calculate the runoff flow and water quality in this basin. Using the water quality results, a load duration curve was constructed for the basin, the exceedance frequency of the water quality standard was calculated for each hydrologic condition class, and the percent reduction required to achieve the water quality standard was estimated. The R(2) value for the calibrated BOD5 was 0.60, which is a moderate result, and the R(2) value for the TP was 0.86, which is a good result. The percent differences obtained for the calibrated BOD5 and TP were very good; therefore, the calibration results using WMCIG were satisfactory. From the load duration curve analysis, the WQS exceedance frequencies of the BOD5 under dry conditions and low-flow conditions were 75.7% and 65%, respectively, and the exceedance frequencies under moist and mid-range conditions were higher than under other conditions. The exceedance frequencies of the TP for the high-flow, moist and mid-range conditions were high and the exceedance rate for the high-flow condition was particularly high. Most of the data from the high-flow conditions exceeded the WQSs. Thus, nonpoint-source pollutants from storm-water runoff substantially affected the TP concentration in the Gomakwoncheon.
-
parameter optimization of the qual2k model for a multiple reach river using an Influence Coefficient algorithm
Science of The Total Environment, 2010Co-Authors: Jae Heon ChoAbstract:An Influence Coefficient algorithm and a genetic algorithm (GA) were introduced to develop an automatic calibration model for QUAL2K, the latest version of the QUAL2E river and stream water-quality model. The Influence Coefficient algorithm was used for the parameter optimization in unsteady state, open channel flow. The GA, used in solving the optimization problem, is very simple and comprehensible yet still applicable to any complicated mathematical problem, where it can find the global-optimum solution quickly and effectively. The previously established model QUAL2Kw was used for the automatic calibration of the QUAL2K. The parameter-optimization method using the Influence Coefficient and genetic algorithm (POMIG) developed in this study and QUAL2Kw were each applied to the Gangneung Namdaecheon River, which has multiple reaches, and the results of the two models were compared. In the modeling, the river reach was divided into two parts based on considerations of the water quality and hydraulic characteristics. The calibration results by POMIG showed a good correspondence between the calculated and observed values for most of water-quality variables. In the application of POMIG and QUAL2Kw, relatively large errors were generated between the observed and predicted values in the case of the dissolved oxygen (DO) and chlorophyll-a (Chl-a) in the lowest part of the river; therefore, two weighting factors (1 and 5) were applied for DO and Chl-a in the lower river. The sums of the errors for DO and Chl-a with a weighting factor of 5 were slightly lower compared with the application of a factor of 1. However, with a weighting factor of 5 the sums of errors for other water-quality variables were slightly increased in comparison to the case with a factor of 1. Generally, the results of the POMIG were slightly better than those of the QUAL2Kw.
Dan Erwin - One of the best experts on this subject based on the ideXlab platform.
-
comparison of theoretical and experimental unsteady aerodynamics of linear oscillating cascade with supersonic leading edge locus video
2004Co-Authors: John K Ramsey, Dan ErwinAbstract:An experimental Influence Coefficient technique was used to obtain unsteady aerodynamic Influence Coefficients and, consequently, unsteady pressures for a cascade of symmetric airfoils oscillating in pitch about mid-chord. Stagger angles of 0 deg and 10 deg were investigated for a cascade with a gap-to-chord ratio of 0.417 operating at an axial Mach number of 1.9, resulting in a supersonic leading-edge locus. Reduced frequencies ranged from 0.056 to 0.2. The Influence Coefficients obtained determine the unsteady pressures for any interblade phase angle. The unsteady pressures were compared with those predicted by several algorithms for interblade phase angles of 0 deg and 180 deg.