2016年9月29日，在工业和信息化部电子信息司指导下，虚拟现实产业联盟（Industry of Virtual Reality Alliance，简称IVRA）在北京成立。工业和信息化部总工程师张峰出席成立大会，并指出中国必须要把握战略窗口机遇期，深化认识、尽...2016年9月29日，在工业和信息化部电子信息司指导下，虚拟现实产业联盟（Industry of Virtual Reality Alliance，简称IVRA）在北京成立。工业和信息化部总工程师张峰出席成立大会，并指出中国必须要把握战略窗口机遇期，深化认识、尽早谋划、科学布局，以虚拟现实技术带来的广阔前景为契机，一手抓产业发展，一手抓安全保障，实现虚拟现实产业决速健康有序发展。展开更多
The successful rate of transmission coordination of opportunistic routing （OK） is analyzea systematically, and then two efficient transmission coordination mechanisms （TCMs） are proposed for OR： a batch sliding w...The successful rate of transmission coordination of opportunistic routing （OK） is analyzea systematically, and then two efficient transmission coordination mechanisms （TCMs） are proposed for OR： a batch sliding window-based TCM and a bit map-based TCM, to reduce the total number of packet transmissions and improve end-to-end throughput for OR. The batch sliding window-based TCM avoids the oscillation of the successful rate of transmission coordination by transmitting packets in continuous batch mode so as to improve the average successful rate of transmission coordination efficiently, while the bit map-based TCM improves end-to-end throughput of OR by reducing the overhead of transmission coordination. Exhaustive simulations show that the average end-to-end throughput gains of the two proposed TCMs are 15.4% and 6.4% over the batch map-based TCM, respectively.展开更多
Wavelet denoising is an effective approach to extract fault features from strong background noise.It has been widely used in mechanical fault detection and shown excellent performance.However,traditional thresholds ar...Wavelet denoising is an effective approach to extract fault features from strong background noise.It has been widely used in mechanical fault detection and shown excellent performance.However,traditional thresholds are not suitable for nonstationary signal denoising because they set universal thresholds for different wavelet coefficients.Therefore,a data-driven threshold strategy is proposed in this paper.First,the signal is decomposed into different subbands by wavelet transformation.Then a data-driven threshold is derived by estimating the noise power spectral density in different subbands.Since the data-driven threshold is dependent on the noise estimation and adapted to data,it is more robust and accurate for denoising than traditional thresholds.Meanwhile,sliding window method is adopted to set a flexible local threshold.When this method was applied to simulation signal and an inner race fault diagnostic case of dedusting fan bearing,the proposed method has good result and provides valuable advantages over traditional methods in the fault detection of rotating machines.展开更多
文摘2016年9月29日，在工业和信息化部电子信息司指导下，虚拟现实产业联盟（Industry of Virtual Reality Alliance，简称IVRA）在北京成立。工业和信息化部总工程师张峰出席成立大会，并指出中国必须要把握战略窗口机遇期，深化认识、尽早谋划、科学布局，以虚拟现实技术带来的广阔前景为契机，一手抓产业发展，一手抓安全保障，实现虚拟现实产业决速健康有序发展。
文摘The successful rate of transmission coordination of opportunistic routing （OK） is analyzea systematically, and then two efficient transmission coordination mechanisms （TCMs） are proposed for OR： a batch sliding window-based TCM and a bit map-based TCM, to reduce the total number of packet transmissions and improve end-to-end throughput for OR. The batch sliding window-based TCM avoids the oscillation of the successful rate of transmission coordination by transmitting packets in continuous batch mode so as to improve the average successful rate of transmission coordination efficiently, while the bit map-based TCM improves end-to-end throughput of OR by reducing the overhead of transmission coordination. Exhaustive simulations show that the average end-to-end throughput gains of the two proposed TCMs are 15.4% and 6.4% over the batch map-based TCM, respectively.
基金supported by the National Natural Science Foundation of China(Grant No.51275384)the Key project of National Natural Science Foundation of China(Grant No.51035007)+1 种基金the National Basic Research Program of China("973"Project)(Grant No.2011CB706805)the Specialized Research Fund for the Doctoral Program of Higher Education(Grant No.20110201130001)
文摘Wavelet denoising is an effective approach to extract fault features from strong background noise.It has been widely used in mechanical fault detection and shown excellent performance.However,traditional thresholds are not suitable for nonstationary signal denoising because they set universal thresholds for different wavelet coefficients.Therefore,a data-driven threshold strategy is proposed in this paper.First,the signal is decomposed into different subbands by wavelet transformation.Then a data-driven threshold is derived by estimating the noise power spectral density in different subbands.Since the data-driven threshold is dependent on the noise estimation and adapted to data,it is more robust and accurate for denoising than traditional thresholds.Meanwhile,sliding window method is adopted to set a flexible local threshold.When this method was applied to simulation signal and an inner race fault diagnostic case of dedusting fan bearing,the proposed method has good result and provides valuable advantages over traditional methods in the fault detection of rotating machines.
