In order to improve the accuracy of cable fault position location at a low cost and make the testing results intuitive, a cable fault detector based on wave form reconstruction is designed. In this detector, the cable...In order to improve the accuracy of cable fault position location at a low cost and make the testing results intuitive, a cable fault detector based on wave form reconstruction is designed. In this detector, the cable fault position is located based on the time-domain pulse reflection （TDR） principle. A pulse waveform is injected in the tested cable, and a high-speed comparator with changeable reference voltages is used to binarize the test pulse waveform to a binary sequence on a certain voltage. Through scanning the reference voltage in a full voltage range, multi-sequences are acquired to reconstruct the pulse waveform transmission in the cable, and then the pulse attenuation feature, electrical open circuit fault, electrical short circuit fault, and the fault position of the cable are diagnosed. Experimental results show that the designed cable fault detector can determine the fault type and its position of the cable being tested, and the testing results are intuitive.展开更多
Two loosely coupled single degree of freedom (SDOF) systems were used to model the flexural and direct shear responses of one-way reinforced concrete slabs subjected to explosive loading. Blast test results show that ...Two loosely coupled single degree of freedom (SDOF) systems were used to model the flexural and direct shear responses of one-way reinforced concrete slabs subjected to explosive loading. Blast test results show that the SDOF systems are accurate in predicting the failure mode of the slab under blast loads by incorporating the effects of the strain rate effect caused by rapid load application. Based on different damage criteria, pressure-impulse (P-I) diagrams of the two failure modes were analyzed with the SDOF systems. The effects of span length, concrete strength, and reinforcement ratio of the slab on the P-I diagram were also investigated. Results indicate that a slab tends to fail in direct shear mode when it is of a smaller span length and tends to fail in flexure mode when it is of a larger span length. With the increase of the concrete strength or reinforced ratio, both the flexure and shear capacity increase. Based on numerical results, a simplified method and a semi analytical equation for deriving the P-I diagram are proposed for different failure modes and damage levels.展开更多
A simple method,based on harmonic wavelet analysis is proposed for the decomposition of a given energy bounded signal into a periodic signal and a pulse.Alike a denoising method,the first part signal it might represen...A simple method,based on harmonic wavelet analysis is proposed for the decomposition of a given energy bounded signal into a periodic signal and a pulse.Alike a denoising method,the first part signal it might represent a smooth periodic function while the pulse is a singular unpredicted perturbation (taken as a fault).It will be shown that,under some general conditions,by a simple projection into two disjoint space of functions we can easily separate the periodic component of the signal from the fault (represented by the singular pulse).展开更多
Cosmic radiation has several effects on the On-Board Processing(OBP)platform in satellite communications systems,and Single Event Upsets(SEUs)are one of its most important effects.In order to protect the Finite Impuls...Cosmic radiation has several effects on the On-Board Processing(OBP)platform in satellite communications systems,and Single Event Upsets(SEUs)are one of its most important effects.In order to protect the Finite Impulse Response(FIR)filters against SEU,this paper proposes a novel Residue Number(RN)-based method.The proposed method applies the transpose form of the FIR filter to avoid the fault missing caused by SEU on shift registers.It also adjusts the input intelligently to avoid the fault missing caused by SEU on the filter coefficients.After all the fault missing events are avoided,the modulus can be minimised to achieve the minimum overhead.Theoretical analysis and simulation results show that the noise introduced by the input adjustment is negligible.Fault injection shows that the fault missing rate of the proposed method is zero.Finally,FPGA implementation shows that the overhead of the proposed method is approximately 75% of Triple Modular Redundancy,and is only 1%-2% higher than that of the traditional RN-based design.展开更多
基金The National Natural Science Foundation of China(No.61240032)the Natural Science Foundation of Jiangsu Province(No.BK2012560)+1 种基金the College Scientific and Technological Achievements Transformation Promotion Project of Jiangsu Province(No.JH-05)the Science and Technology Support Program of Jiangsu Province(No.BE2012740)
文摘In order to improve the accuracy of cable fault position location at a low cost and make the testing results intuitive, a cable fault detector based on wave form reconstruction is designed. In this detector, the cable fault position is located based on the time-domain pulse reflection （TDR） principle. A pulse waveform is injected in the tested cable, and a high-speed comparator with changeable reference voltages is used to binarize the test pulse waveform to a binary sequence on a certain voltage. Through scanning the reference voltage in a full voltage range, multi-sequences are acquired to reconstruct the pulse waveform transmission in the cable, and then the pulse attenuation feature, electrical open circuit fault, electrical short circuit fault, and the fault position of the cable are diagnosed. Experimental results show that the designed cable fault detector can determine the fault type and its position of the cable being tested, and the testing results are intuitive.
基金Project(JC11-02-18) supported by the Scientific Foundation of National University of Defense Technology, ChinaProject(11202236) supported by the National Natural Science Foundation of China
文摘Two loosely coupled single degree of freedom (SDOF) systems were used to model the flexural and direct shear responses of one-way reinforced concrete slabs subjected to explosive loading. Blast test results show that the SDOF systems are accurate in predicting the failure mode of the slab under blast loads by incorporating the effects of the strain rate effect caused by rapid load application. Based on different damage criteria, pressure-impulse (P-I) diagrams of the two failure modes were analyzed with the SDOF systems. The effects of span length, concrete strength, and reinforcement ratio of the slab on the P-I diagram were also investigated. Results indicate that a slab tends to fail in direct shear mode when it is of a smaller span length and tends to fail in flexure mode when it is of a larger span length. With the increase of the concrete strength or reinforced ratio, both the flexure and shear capacity increase. Based on numerical results, a simplified method and a semi analytical equation for deriving the P-I diagram are proposed for different failure modes and damage levels.
文摘A simple method,based on harmonic wavelet analysis is proposed for the decomposition of a given energy bounded signal into a periodic signal and a pulse.Alike a denoising method,the first part signal it might represent a smooth periodic function while the pulse is a singular unpredicted perturbation (taken as a fault).It will be shown that,under some general conditions,by a simple projection into two disjoint space of functions we can easily separate the periodic component of the signal from the fault (represented by the singular pulse).
基金supported by the National High Technical Research and Development Program of China (863 Program) "Research on the Key Technology for the Base Band Signal Processing for Onboard Payload"the Sino-Japan Joint Fund "Key Technique Research for GSS Integrated Mobile Satellite Communications"+2 种基金Tsinghua University Initiative Scientific Research Program "Key Technologies of SkyEarth Integration Wireless Communication Network" under Grant No. 2010 THZ03the National Key Basic Research Program of China(973 Program) under Grant No. 2012CB316000the Spanish Ministry of Science and Education under Grant No. AYA2009-13300-C03
文摘Cosmic radiation has several effects on the On-Board Processing(OBP)platform in satellite communications systems,and Single Event Upsets(SEUs)are one of its most important effects.In order to protect the Finite Impulse Response(FIR)filters against SEU,this paper proposes a novel Residue Number(RN)-based method.The proposed method applies the transpose form of the FIR filter to avoid the fault missing caused by SEU on shift registers.It also adjusts the input intelligently to avoid the fault missing caused by SEU on the filter coefficients.After all the fault missing events are avoided,the modulus can be minimised to achieve the minimum overhead.Theoretical analysis and simulation results show that the noise introduced by the input adjustment is negligible.Fault injection shows that the fault missing rate of the proposed method is zero.Finally,FPGA implementation shows that the overhead of the proposed method is approximately 75% of Triple Modular Redundancy,and is only 1%-2% higher than that of the traditional RN-based design.
