By introducing the bit-level multi-stream coded Layered Space-Time （LST） transmitter along with a novel iterative MultiStage Decoding （MSD） at the receiver, the paper shows how to achieve the near-capacity perform...By introducing the bit-level multi-stream coded Layered Space-Time （LST） transmitter along with a novel iterative MultiStage Decoding （MSD） at the receiver, the paper shows how to achieve the near-capacity performance of the Multiple-Input Multiple-Output （MIMO） systems with square Quadrature Amplitude Modulation （QAM）. In the proposed iterative MSD scheme, the detection at each stage is equivalent to multiuser detection of synchronous Code Division Multiple Access （CDMA） multiuser systems with the aid of the binary representation of the transmitted symbols. Therefore, the optimal Soft-Input Soft-Output （SISO） multiuser detection and low-complexity SISO multiuser detection can be utilized herein. And the proposed scheme with low-complexity SISO multiuser detection has polynomial complexity in the number of transmit antennas M, the number of receive antennas N, and the number of bits per constellation point Me. Simulation results demonstrate that the proposed scheme has similar Bit Error Rate （BER） performance to that of the known Iterative Tree Search （ITS） detection.展开更多
This paper presents a predictive defect detection method for prototype additive manufacturing(AM)based on multilayer susceptibility discrimination(MSD).Most current methods are significantly limited by merely captured...This paper presents a predictive defect detection method for prototype additive manufacturing(AM)based on multilayer susceptibility discrimination(MSD).Most current methods are significantly limited by merely captured images,disregarding the differences between layer-by-layer manufacturing approaches,without combining transcendental knowledge.The visible parts,originating from the prototype of conceptual design,are determined based on spherical flipping and convex hull theory,on the basis of which theoretical template image(TTI)is rendered according to photorealistic technology.In addition,to jointly consider the differences in AM processes,the finite element method(FEM)of transient thermal-structure coupled analysis was conducted to probe susceptible regions where defects appeared with a higher possibility.Driven by prior knowledge acquired from the FEM analysis,the MSD with an adaptive threshold,which discriminated the sensitivity and susceptibility of each layer,was implemented to determine defects.The anomalous regions were detected and refined by superimposing multiple-layer anomalous regions and comparing the structural features extracted using the Chan-Vese(CV)model.A physical experiment was performed via digital light processing(DLP)with photosensitive resin of a non-faceted scaled V-shaped engine block prototype with cylindrical holes using a non-contact profilometer.This MSD method is practical for detecting defects and is valuable for a deeper exploration of barely visible impact damage(BVID),thereby reducing the defect of prototypical mechanical parts in engineering machinery or process equipment via intellectualized machinevision.展开更多
基金the National Natural Science Foundation of China (No. 60472098 and No. 60502046).
文摘By introducing the bit-level multi-stream coded Layered Space-Time （LST） transmitter along with a novel iterative MultiStage Decoding （MSD） at the receiver, the paper shows how to achieve the near-capacity performance of the Multiple-Input Multiple-Output （MIMO） systems with square Quadrature Amplitude Modulation （QAM）. In the proposed iterative MSD scheme, the detection at each stage is equivalent to multiuser detection of synchronous Code Division Multiple Access （CDMA） multiuser systems with the aid of the binary representation of the transmitted symbols. Therefore, the optimal Soft-Input Soft-Output （SISO） multiuser detection and low-complexity SISO multiuser detection can be utilized herein. And the proposed scheme with low-complexity SISO multiuser detection has polynomial complexity in the number of transmit antennas M, the number of receive antennas N, and the number of bits per constellation point Me. Simulation results demonstrate that the proposed scheme has similar Bit Error Rate （BER） performance to that of the known Iterative Tree Search （ITS） detection.
基金funded by the National Key Research and Development Project of China(Grant No.2022YFB3303303)Zhejiang Scientific Research and Development Project(Grant No.LZY22E060002)+2 种基金Key Program of the National Natural Science Foundation of China(Grant Nos.51935009,U22A6001)The Ng Teng Fong Charitable Foundation in the form of a ZJU-SUTD IDEA Grant(Grant No.188170-11102)Zhejiang University President Special Fund financed by Zhejiang province(Grant No.2021XZZX008).
文摘This paper presents a predictive defect detection method for prototype additive manufacturing(AM)based on multilayer susceptibility discrimination(MSD).Most current methods are significantly limited by merely captured images,disregarding the differences between layer-by-layer manufacturing approaches,without combining transcendental knowledge.The visible parts,originating from the prototype of conceptual design,are determined based on spherical flipping and convex hull theory,on the basis of which theoretical template image(TTI)is rendered according to photorealistic technology.In addition,to jointly consider the differences in AM processes,the finite element method(FEM)of transient thermal-structure coupled analysis was conducted to probe susceptible regions where defects appeared with a higher possibility.Driven by prior knowledge acquired from the FEM analysis,the MSD with an adaptive threshold,which discriminated the sensitivity and susceptibility of each layer,was implemented to determine defects.The anomalous regions were detected and refined by superimposing multiple-layer anomalous regions and comparing the structural features extracted using the Chan-Vese(CV)model.A physical experiment was performed via digital light processing(DLP)with photosensitive resin of a non-faceted scaled V-shaped engine block prototype with cylindrical holes using a non-contact profilometer.This MSD method is practical for detecting defects and is valuable for a deeper exploration of barely visible impact damage(BVID),thereby reducing the defect of prototypical mechanical parts in engineering machinery or process equipment via intellectualized machinevision.
