This paper outlines the significance of enhancing the instantaneous protection reliability of low voltage circuit breakers and describes their main failure modes. The instantaneous failure mechanism of low voltage cir...This paper outlines the significance of enhancing the instantaneous protection reliability of low voltage circuit breakers and describes their main failure modes. The instantaneous failure mechanism of low voltage circuit breakers was analyzed so that measures to improve instantaneous protection reliability can be determined. Furthermore, the theory of the instantaneous characteristics calibration device for low voltage circuit breakers and the method of eliminating the non-periodic component of test current are given in detail. Finally, the test results are presented.展开更多
The instantaneous total mortality rate(Z) of a fish population is one of the important parameters in fisheries stock assessment. The estimation of Z is crucial to fish population dynamics analysis,abundance and catch ...The instantaneous total mortality rate(Z) of a fish population is one of the important parameters in fisheries stock assessment. The estimation of Z is crucial to fish population dynamics analysis,abundance and catch forecast,and fisheries management. A catch curve-based method for estimating time-based Z and its change trend from catch per unit effort(CPUE) data of multiple cohorts is developed. Unlike the traditional catch-curve method,the method developed here does not need the assumption of constant Z throughout the time,but the Z values in n continuous years are assumed constant,and then the Z values in different n continuous years are estimated using the age-based CPUE data within these years. The results of the simulation analyses show that the trends of the estimated time-based Z are consistent with the trends of the true Z,and the estimated rates of change from this approach are close to the true change rates(the relative differences between the change rates of the estimated Z and the true Z are smaller than 10%). Variations of both Z and recruitment can affect the estimates of Z value and the trend of Z. The most appropriate value of n can be different given the effects of different factors. Therefore,the appropriate value of n for different fisheries should be determined through a simulation analysis as we demonstrated in this study. Further analyses suggested that selectivity and age estimation are also two factors that can affect the estimated Z values if there is error in either of them,but the estimated change rates of Z are still close to the true change rates. We also applied this approach to the Atlantic cod(G adus morhua) fishery of eastern Newfoundland and Labrador from 1983 to 1997,and obtained reasonable estimates of time-based Z.展开更多
XPS and chemical trapping experments with H2, NH3, and CH3I as trapping agents were carried out for studying the adsorption of propylene over MoO3 or r-Bi2MoO6. The results show that the fragmentation of carbon chain ...XPS and chemical trapping experments with H2, NH3, and CH3I as trapping agents were carried out for studying the adsorption of propylene over MoO3 or r-Bi2MoO6. The results show that the fragmentation of carbon chain takes place during the adsorption of propylene through breaking C -C double bond and C-C bond on Mo2+ and the adjacent lattice oxygen, leading to formation of the oxygen- or nitrogen-containing by-products of C1 and C2 species. Diffuse-Reflection Fourier Transform Infrared (DRFTIR) Spectroscopy was used to study the surface species formed during the chemisorption and reaction of propylene over y-Bi2MoO6 at a lower temperature. The results that C1, C2 adspecies were detected by DRFTIR at 175℃ are consistent with the results of XPS and chemical trapping experiments, whlle the results at 50℃ Grasselli et al.展开更多
An adaptive approach to select analysis window param- eters for linear frequency modulated （LFM） signals is proposed to obtain the optimal 3 dB signal-to-noise ratio （SNR） in the short- time Fourier transform （S...An adaptive approach to select analysis window param- eters for linear frequency modulated （LFM） signals is proposed to obtain the optimal 3 dB signal-to-noise ratio （SNR） in the short- time Fourier transform （STFT） domain. After analyzing the instan- taneous frequency and instantaneous bandwidth to deduce the relation between the window length and deviation of the Gaus- sian window, high-order statistics is used to select the appropriate window length for STFT and get the optimal SNR with the right time-frequency resolution according to the signal characteristic under a fixed sampling rate. Computer simulations have verified the effectiveness of the new method.展开更多
In cognitive radio (CR) relay networks,most previous work concentrates on maximizing physical layer quality of service (QoS),e.g.,spectral efficiency and achievable data rate,as relay selection criteria.However,the re...In cognitive radio (CR) relay networks,most previous work concentrates on maximizing physical layer quality of service (QoS),e.g.,spectral efficiency and achievable data rate,as relay selection criteria.However,the residual energy state of relay nodes is largely ignored,which has significant effects on the average network lifetime for those battery-limited wireless networks.In this paper,an opportunistic distributed best-relay node selection scheme is proposed for cooperative transmissions over underlay-paradigm based CR networks,and meanwhile guarantee that the primary link is provided with a minimum-rate for a certain percentage of time.The objective is to increase achievable data rate as well as prolong average network lifetime.Specifically,both the instantaneous channel state information (ICSI) and residual energy of candidate relay nodes are taken as weighted metric,and the relay node with the optimal weighted metric is selected as the best one.Simulation results are presented to demonstrate the effectiveness of the proposed scheme.展开更多
基金Project (No. 043804411) supported by the Tianjin Natural ScienceFoundation, China
文摘This paper outlines the significance of enhancing the instantaneous protection reliability of low voltage circuit breakers and describes their main failure modes. The instantaneous failure mechanism of low voltage circuit breakers was analyzed so that measures to improve instantaneous protection reliability can be determined. Furthermore, the theory of the instantaneous characteristics calibration device for low voltage circuit breakers and the method of eliminating the non-periodic component of test current are given in detail. Finally, the test results are presented.
基金Supported by the USDA Cooperative State Research,Education and Extension Service,Hatch Project(No.0210510)the National Natural Science Foundations of China(Nos.31270527,40801225)+1 种基金the Natural Science Foundation of Zhejiang Province(No.LY13D010005)the Young Academic Leaders Climbing Program of Zhejiang Province(No.pd2013222)
文摘The instantaneous total mortality rate(Z) of a fish population is one of the important parameters in fisheries stock assessment. The estimation of Z is crucial to fish population dynamics analysis,abundance and catch forecast,and fisheries management. A catch curve-based method for estimating time-based Z and its change trend from catch per unit effort(CPUE) data of multiple cohorts is developed. Unlike the traditional catch-curve method,the method developed here does not need the assumption of constant Z throughout the time,but the Z values in n continuous years are assumed constant,and then the Z values in different n continuous years are estimated using the age-based CPUE data within these years. The results of the simulation analyses show that the trends of the estimated time-based Z are consistent with the trends of the true Z,and the estimated rates of change from this approach are close to the true change rates(the relative differences between the change rates of the estimated Z and the true Z are smaller than 10%). Variations of both Z and recruitment can affect the estimates of Z value and the trend of Z. The most appropriate value of n can be different given the effects of different factors. Therefore,the appropriate value of n for different fisheries should be determined through a simulation analysis as we demonstrated in this study. Further analyses suggested that selectivity and age estimation are also two factors that can affect the estimated Z values if there is error in either of them,but the estimated change rates of Z are still close to the true change rates. We also applied this approach to the Atlantic cod(G adus morhua) fishery of eastern Newfoundland and Labrador from 1983 to 1997,and obtained reasonable estimates of time-based Z.
基金Supported by the National Natural Science Fundation of China.
文摘XPS and chemical trapping experments with H2, NH3, and CH3I as trapping agents were carried out for studying the adsorption of propylene over MoO3 or r-Bi2MoO6. The results show that the fragmentation of carbon chain takes place during the adsorption of propylene through breaking C -C double bond and C-C bond on Mo2+ and the adjacent lattice oxygen, leading to formation of the oxygen- or nitrogen-containing by-products of C1 and C2 species. Diffuse-Reflection Fourier Transform Infrared (DRFTIR) Spectroscopy was used to study the surface species formed during the chemisorption and reaction of propylene over y-Bi2MoO6 at a lower temperature. The results that C1, C2 adspecies were detected by DRFTIR at 175℃ are consistent with the results of XPS and chemical trapping experiments, whlle the results at 50℃ Grasselli et al.
基金supported by the National Natural Science Foundation of China(6107313361175053+8 种基金6127236960975019)the Heilongjiang Postdoctoral Grant(LRB08362)the Fundamental Research Funds for the Central Universities of China(2011QN0272011QN1262012QN0302011ZD010)the Science and Technology Planning Project of Dalian City(2011A17GX0732010E15SF153)
文摘An adaptive approach to select analysis window param- eters for linear frequency modulated （LFM） signals is proposed to obtain the optimal 3 dB signal-to-noise ratio （SNR） in the short- time Fourier transform （STFT） domain. After analyzing the instan- taneous frequency and instantaneous bandwidth to deduce the relation between the window length and deviation of the Gaus- sian window, high-order statistics is used to select the appropriate window length for STFT and get the optimal SNR with the right time-frequency resolution according to the signal characteristic under a fixed sampling rate. Computer simulations have verified the effectiveness of the new method.
基金Sponsored by the National Major Science&Technology Project(Grand No.2009ZX03002-014)the National Nature Science Foundation(Grant No.60832009)+1 种基金the Beijing Municipal Natural Science Foundation(Grand No.4102044)the National Natural Science Foundation for Distinguished Young Scholar(Grand No.61001115)
文摘In cognitive radio (CR) relay networks,most previous work concentrates on maximizing physical layer quality of service (QoS),e.g.,spectral efficiency and achievable data rate,as relay selection criteria.However,the residual energy state of relay nodes is largely ignored,which has significant effects on the average network lifetime for those battery-limited wireless networks.In this paper,an opportunistic distributed best-relay node selection scheme is proposed for cooperative transmissions over underlay-paradigm based CR networks,and meanwhile guarantee that the primary link is provided with a minimum-rate for a certain percentage of time.The objective is to increase achievable data rate as well as prolong average network lifetime.Specifically,both the instantaneous channel state information (ICSI) and residual energy of candidate relay nodes are taken as weighted metric,and the relay node with the optimal weighted metric is selected as the best one.Simulation results are presented to demonstrate the effectiveness of the proposed scheme.
