Time-differences-of-arrival （TDOA） and gain-ratios-of- arrival （GROA） measurements are used to determine the passive source location. Based on the measurement models, the con- strained weighted least squares （CWL...Time-differences-of-arrival （TDOA） and gain-ratios-of- arrival （GROA） measurements are used to determine the passive source location. Based on the measurement models, the con- strained weighted least squares （CWLS） estimator is presented. Due to the nonconvex nature of the CWLS problem, it is difficult to obtain its globally optimal solution. However, according to the semidefinite relaxation, the CWLS problem can be relaxed as a convex semidefinite programming problem （SDP）, which can be solved by using modern convex optimization algorithms. Moreover, this relaxation can be proved to be tight, i.e., the SDP solves the relaxed CWLS problem, and this hence guarantees the good per- formance of the proposed method. Furthermore, this method is extended to solve the localization problem with sensor position errors. Simulation results corroborate the theoretical results and the good performance of the proposed method.展开更多
In this study,influence of back-wall clearance,CWL(Critical Water Level)and air content in water on flow patterns in a pump intake has been investigated experimentally and theoretically for different cases.The statist...In this study,influence of back-wall clearance,CWL(Critical Water Level)and air content in water on flow patterns in a pump intake has been investigated experimentally and theoretically for different cases.The statistical data show that CWL for a two-phase flow is lower than that in the case of a single-phase flow at a relatively low flow rate,and as the flow rate increases,this trend turns out to be completely reversed.Fine experimental data obtained under conditions of subcritical,critical and supercritical flow rates have revealed that the larger the back-wall clearance is,the more vortices exist and the higher the vorticity of free-surface vortices is.For the smallest back-wall clearance,the flow coming through the inlet occupies most space under the pipe bell,and both this flow and the inflow coming from the back wall are asymmetric relative to a certain vertical line other than the axis.For the larger and the largest back-wall clearances,the flows coming from the inlet and from the back wall are almost symmetrical relative to the vertical axis of the pipe bell.The velocity distributions on two PIV measurement lines for different back-wall clearance magnitudes indicate that the smallest back-wall clearance influences the flow around the pipe bell.展开更多
基金supported by the National Natural Science Foundation of China(61201282)the Science and Technology on Communication Information Security Control Laboratory Foundation(9140C130304120C13064)
文摘Time-differences-of-arrival （TDOA） and gain-ratios-of- arrival （GROA） measurements are used to determine the passive source location. Based on the measurement models, the con- strained weighted least squares （CWLS） estimator is presented. Due to the nonconvex nature of the CWLS problem, it is difficult to obtain its globally optimal solution. However, according to the semidefinite relaxation, the CWLS problem can be relaxed as a convex semidefinite programming problem （SDP）, which can be solved by using modern convex optimization algorithms. Moreover, this relaxation can be proved to be tight, i.e., the SDP solves the relaxed CWLS problem, and this hence guarantees the good per- formance of the proposed method. Furthermore, this method is extended to solve the localization problem with sensor position errors. Simulation results corroborate the theoretical results and the good performance of the proposed method.
基金supported by the National Natural Science Foundation of China(Grant Nos.51909132,52079140,51779257).
文摘In this study,influence of back-wall clearance,CWL(Critical Water Level)and air content in water on flow patterns in a pump intake has been investigated experimentally and theoretically for different cases.The statistical data show that CWL for a two-phase flow is lower than that in the case of a single-phase flow at a relatively low flow rate,and as the flow rate increases,this trend turns out to be completely reversed.Fine experimental data obtained under conditions of subcritical,critical and supercritical flow rates have revealed that the larger the back-wall clearance is,the more vortices exist and the higher the vorticity of free-surface vortices is.For the smallest back-wall clearance,the flow coming through the inlet occupies most space under the pipe bell,and both this flow and the inflow coming from the back wall are asymmetric relative to a certain vertical line other than the axis.For the larger and the largest back-wall clearances,the flows coming from the inlet and from the back wall are almost symmetrical relative to the vertical axis of the pipe bell.The velocity distributions on two PIV measurement lines for different back-wall clearance magnitudes indicate that the smallest back-wall clearance influences the flow around the pipe bell.
