Based on chaotic oscillator system, this paper proposes a novel method on high frequency low signal-to-noise ratio BPSK(Binary Phase Shift Keying) signal detection. Chaotic oscillator system is a typical non-linear sy...Based on chaotic oscillator system, this paper proposes a novel method on high frequency low signal-to-noise ratio BPSK(Binary Phase Shift Keying) signal detection. Chaotic oscillator system is a typical non-linear system which is sensitive to periodic signals and immune to noise at the same time. Those properties make it possible to detect low signal-to-noise ratio signals. The BPSK signal is a common signal type which is widely used in modern communication. Starting from the analysis of advantages of chaotic oscillator system and signal features of the BPSK signal, we put forward a unique method that can detect low signal-to-noise ratio BPSK signals with high frequency. The simulation results show that the novel method can detect low signal-to-noise ratio BPSK signals with frequency in an order of magnitude of 108 Hz, and the input Signal-to-Noise Ratio threshold can be -20 dB.展开更多
Weak signal reception is a very important and challenging problem for communication systems especially in the presence of non-Gaussian noise,and in which case the performance of optimal linear correlated receiver degr...Weak signal reception is a very important and challenging problem for communication systems especially in the presence of non-Gaussian noise,and in which case the performance of optimal linear correlated receiver degrades dramatically.Aiming at this,a novel uncorrelated reception scheme based on adaptive bistable stochastic resonance(ABSR)for a weak signal in additive Laplacian noise is investigated.By analyzing the key issue that the quantitative cooperative resonance matching relationship between the characteristics of the noisy signal and the nonlinear bistable system,an analytical expression of the bistable system parameters is derived.On this basis,by means of bistable system parameters self-adaptive adjustment,the counterintuitive stochastic resonance(SR)phenomenon can be easily generated at which the random noise is changed into a benefit to assist signal transmission.Finally,it is demonstrated that approximately 8dB bit error ratio(BER)performance improvement for the ABSR-based uncorrelated receiver when compared with the traditional uncorrelated receiver at low signal to noise ratio(SNR)conditions varying from-30dB to-5dB.展开更多
Low temperature as abiotic stress adversely impacts plant growth and development, and limits the ecological distribution of plants as well. Throughout their long evolutionary history, plants have developed a range of ...Low temperature as abiotic stress adversely impacts plant growth and development, and limits the ecological distribution of plants as well. Throughout their long evolutionary history, plants have developed a range of complicated and precise molecular regulatory mechanisms to deal with low-temperature stress, involving the activation of signal transduction pathways and the regulation of related genes. In this review, we provide a systematic summary of the most recent research findings regarding three hypotheses of cellular perception of low-temperature signals and two major intracellular low-temperature signaling pathways, including CBF-dependent signaling pathways and CBF-independent signaling pathways. Focus is placed on the functions of each component of the ICE-CBF-COR signaling cascade as well as their interrelationships. This review concludes that although some progress has been made in the identification, function, and mechanism of low-temperature response genes, their roles in the low-temperature regulatory network and molecular mechanisms still need to be studied in detail, which will be of great significance for improving the low-temperature tolerance of plants and adapting to climate change.展开更多
Bearing condition monitoring and fault diagnosis (CMFD) can investigate bearing faults in the early stages, preventing the subsequent impacts of machine bearing failures effectively. CMFD for low-speed, non-continuous...Bearing condition monitoring and fault diagnosis (CMFD) can investigate bearing faults in the early stages, preventing the subsequent impacts of machine bearing failures effectively. CMFD for low-speed, non-continuous operation bearings, such as yaw bearings and pitch bearings in wind turbines, and rotating support bearings in space launch towers, presents more challenges compared to continuous rolling bearings. Firstly, these bearings have very slow speeds, resulting in weak collected fault signals that are heavily masked by severe noise interference. Secondly, their limited rotational angles during operation lead to a restricted number of fault signals. Lastly, the interference from deceleration and direction-changing impact signals significantly affects fault impact signals. To address these challenges, this paper proposes a method for extracting fault features in low-speed reciprocating bearings based on short signal segmentation and modulation signal bispectrum (MSB) slicing. This method initially separates short signals corresponding to individual cycles from the vibration signals based on encoder signals. Subsequently, MSB analysis is performed on each short signal to generate MSB carrier-slice spectra. The optimal carrier frequency and its corresponding modulation signal slice spectrum are determined based on the carrier-slice spectra. Finally, the MSB modulation signal slice spectra of the short signal set are averaged to obtain the overall average feature of the sliced spectra.展开更多
The Radon-ambiguity transform (RAT), although efficient for detecting the linear frequency modulated signals (LFMs), is troubled by the energy accumulation of noise in low signal-to-noise ratio (SNR). A secondor...The Radon-ambiguity transform (RAT), although efficient for detecting the linear frequency modulated signals (LFMs), is troubled by the energy accumulation of noise in low signal-to-noise ratio (SNR). A secondorder difference (SOD) method is proposed to treat with this problem. In the SOD method, the optimal search step and difference step are derived from the LFM rate resolution formula. The sharpness of the peaks of RAT is measured by curvature, and the sharpness, but not the magnitude of the peaks, is used to detect the LFMs. The SOD method removes the noise energy accumulation and reserves the drastically changing components integrally; thus, it improves the detection probability of LFMs in low SNR. The expected performance of the new method is verified by 100 Monte Carlo simulations.展开更多
To boost the performance of 4-ary pulse amplitude modulated(PAM) at low signal-to-noise ratio(SNR), bistable stochastic resonance(BSR) system is introduced into digital communications system and get a reliable signal ...To boost the performance of 4-ary pulse amplitude modulated(PAM) at low signal-to-noise ratio(SNR), bistable stochastic resonance(BSR) system is introduced into digital communications system and get a reliable signal detection scheme. In this paper, we first analyse BSR system for different amplitudes of 4-ary PAM signals. The steadystate of the bistable system will be statistically distinct, and the feasibility of the proposed detection scheme is confirmed. On this basis, we present a detailed study on steady-state transitions of the BSR system, and an explicit expression of the bistable system parameters is derived. By setting the bistable system parameters, bistable system, 4-ary PAM signal, and noise reach the resonance state, and the BSR-based detection scheme is implemented. Moreover, we derive an analytical expression to calculate the symbol error rate(SER) of 4-ary PAM signals with the BSR-based detection under additive white Gaussian noise(AWGN). Finally, the simulation results validate that BSR-based detection scheme can improve the detection performance while efficiently reducing the symbol error rate.展开更多
A new tracking algorithm is proposed aiming at the tracking problem in low bit signal-to- noise ratio (i. e. , Eb/N0 ) scenarios, in which the bit clock regenerated by bit synchronization loop decides loop update mo...A new tracking algorithm is proposed aiming at the tracking problem in low bit signal-to- noise ratio (i. e. , Eb/N0 ) scenarios, in which the bit clock regenerated by bit synchronization loop decides loop update moment. The double frequency processing and non-coherent accumulation tech- nologies are applied to eliminate the impact of data polarity inversion, and then long time accumula- tion improves the input signal-to-noise ratio of discriminator. The frequency locked loop and phase locked loop constitute a carrier loop in parallel, which can meet the high dynamic demands. The ef- fectiveness of this algorithm has been corroborated by theoretical analysis, simulation and measure- ments, and the new tracking algorithm has been used in an aerospace engineering project successfully.展开更多
In order to search for the seismic wave characteristics of low frequency signals in the Alxa Left Banner region,Inner Mongolia,the low frequency signals of seismic wave data are extracted from the earthquakes of MS5. ...In order to search for the seismic wave characteristics of low frequency signals in the Alxa Left Banner region,Inner Mongolia,the low frequency signals of seismic wave data are extracted from the earthquakes of MS5. 8 in 2015 and MS5. 0 in 2016 in this area. The results show that:① Before the MS5. 8 earthquake,the seismic stations located near the epicenter in Wuhai,Dongshengmiao,and Shizuishan recorded seismic waves that showed the phenomenon of spectrum shift from high to low frequency.② The low frequency signals recorded by different stations have obvious difference.③ According to the data recorded by the station closest to the epicenter,low-frequency signals were recorded about120 hours before the earthquake and had obvious anomalies. This may reflect slow slip before the earthquake.展开更多
The essay mainly studies a system of low frequency signal′s measurement and the extraction of its characteristic quantity,introduces how matlab analyzes and extracts low frequency signal.MATLAB,a visual programming s...The essay mainly studies a system of low frequency signal′s measurement and the extraction of its characteristic quantity,introduces how matlab analyzes and extracts low frequency signal.MATLAB,a visual programming software,designs testing program for mechanic vibration signal,analyzes and identifies vibration signal.The collected data shows the effectiveness of the system.Based on XM121 modules,the testing system collects and analyzes single channel signal.展开更多
Low-temperature plasma(LTP) has shown great promise in wound healing,although the underlying mechanism remains poorly understood.In the present study,an argon atmospheric pressure plasma jet was employed to treat L9...Low-temperature plasma(LTP) has shown great promise in wound healing,although the underlying mechanism remains poorly understood.In the present study,an argon atmospheric pressure plasma jet was employed to treat L929 murine fibroblasts cultured in vitro and skin wounds in BALB/c mice.The in vitro analysis revealed that treatment of fibroblasts with LTP for 15 s resulted in a significant increase in cell proliferation,secretion of epidermal growth factor(EGF) and transforming growth factor-β1(TGF-β1),production of intracellular reactive oxygen species(ROS),and the percentage of cells in S phase,protein expression of phosphorylated p65(P-p65) and cyclin D1,but a noted decrease in the protein expression of inhibitor kappa B(IκB).The in vivo experiments demonstrated that 30-s LTP treatment enhanced the number of fibroblasts and the ability of collagen synthesis,while 50-s treatment led to the opposite outcomes.These results suggested that LTP treatment promotes the fibroblast proliferation in wound healing by inducing the generation of ROS,upregulating the expression of P-p65,downregulating the expression of IκB,and activating the NF-κB signaling pathway and consequently altering cell cycle progression(increased DNA synthesis in S phage).展开更多
A low-power complementary metal oxide semiconductor(CMOS) operational amplifier (op-amp) for real-time signal processing of micro air vehicle (MAV) is designed in this paper.Traditional folded cascode architectu...A low-power complementary metal oxide semiconductor(CMOS) operational amplifier (op-amp) for real-time signal processing of micro air vehicle (MAV) is designed in this paper.Traditional folded cascode architecture with positive channel metal oxide semiconductor(PMOS) differential input transistors and sub-threshold technology are applied under the low supply voltage.Simulation results show that this amplifier has significantly low power,while maintaining almost the same gain,bandwidth and other key performances.The power required is only 0.12 mW,which is applicable to low-power and low-voltage real-time signal acquisition and processing system.展开更多
In order to investigate the regularity of metal magnetic signals of ferromagnetic materials under the effect of applied load, the static tensile test of Q235 steel and 18CrNiWA steel plate specimens were conducted and...In order to investigate the regularity of metal magnetic signals of ferromagnetic materials under the effect of applied load, the static tensile test of Q235 steel and 18CrNiWA steel plate specimens were conducted and metal magnetic memory signals of specimens were measured during the test process. The influencing factors of metal magnetic memory signals and the relationship between axial applied load and signals were analyzed. The fracture and microstructure of the specimens were observed. The results show that the magnetic signals corresponding to the measured points change linearly approximately with increasing axial load. The microstructure of Q235 steel is ferrite and perlite, whereas that of 18CrNiWA steel is bainite and low-carbon martensite. The fracture of these two kinds of specimens is ductile rupture; carbon content of specimen materials and dislocation glide give much contribution to the characteristics of magnetic curves.展开更多
文摘Based on chaotic oscillator system, this paper proposes a novel method on high frequency low signal-to-noise ratio BPSK(Binary Phase Shift Keying) signal detection. Chaotic oscillator system is a typical non-linear system which is sensitive to periodic signals and immune to noise at the same time. Those properties make it possible to detect low signal-to-noise ratio signals. The BPSK signal is a common signal type which is widely used in modern communication. Starting from the analysis of advantages of chaotic oscillator system and signal features of the BPSK signal, we put forward a unique method that can detect low signal-to-noise ratio BPSK signals with high frequency. The simulation results show that the novel method can detect low signal-to-noise ratio BPSK signals with frequency in an order of magnitude of 108 Hz, and the input Signal-to-Noise Ratio threshold can be -20 dB.
基金supported in part by the National Natural Science Foundation of China(62001356)in part by the National Natural Science Foundation for Distinguished Young Scholar(61825104)+1 种基金in part by the National Key Research and Development Program of China(2022YFC3301300)in part by the Innovative Research Groups of the National Natural Science Foundation of China(62121001)。
文摘Weak signal reception is a very important and challenging problem for communication systems especially in the presence of non-Gaussian noise,and in which case the performance of optimal linear correlated receiver degrades dramatically.Aiming at this,a novel uncorrelated reception scheme based on adaptive bistable stochastic resonance(ABSR)for a weak signal in additive Laplacian noise is investigated.By analyzing the key issue that the quantitative cooperative resonance matching relationship between the characteristics of the noisy signal and the nonlinear bistable system,an analytical expression of the bistable system parameters is derived.On this basis,by means of bistable system parameters self-adaptive adjustment,the counterintuitive stochastic resonance(SR)phenomenon can be easily generated at which the random noise is changed into a benefit to assist signal transmission.Finally,it is demonstrated that approximately 8dB bit error ratio(BER)performance improvement for the ABSR-based uncorrelated receiver when compared with the traditional uncorrelated receiver at low signal to noise ratio(SNR)conditions varying from-30dB to-5dB.
文摘Low temperature as abiotic stress adversely impacts plant growth and development, and limits the ecological distribution of plants as well. Throughout their long evolutionary history, plants have developed a range of complicated and precise molecular regulatory mechanisms to deal with low-temperature stress, involving the activation of signal transduction pathways and the regulation of related genes. In this review, we provide a systematic summary of the most recent research findings regarding three hypotheses of cellular perception of low-temperature signals and two major intracellular low-temperature signaling pathways, including CBF-dependent signaling pathways and CBF-independent signaling pathways. Focus is placed on the functions of each component of the ICE-CBF-COR signaling cascade as well as their interrelationships. This review concludes that although some progress has been made in the identification, function, and mechanism of low-temperature response genes, their roles in the low-temperature regulatory network and molecular mechanisms still need to be studied in detail, which will be of great significance for improving the low-temperature tolerance of plants and adapting to climate change.
文摘Bearing condition monitoring and fault diagnosis (CMFD) can investigate bearing faults in the early stages, preventing the subsequent impacts of machine bearing failures effectively. CMFD for low-speed, non-continuous operation bearings, such as yaw bearings and pitch bearings in wind turbines, and rotating support bearings in space launch towers, presents more challenges compared to continuous rolling bearings. Firstly, these bearings have very slow speeds, resulting in weak collected fault signals that are heavily masked by severe noise interference. Secondly, their limited rotational angles during operation lead to a restricted number of fault signals. Lastly, the interference from deceleration and direction-changing impact signals significantly affects fault impact signals. To address these challenges, this paper proposes a method for extracting fault features in low-speed reciprocating bearings based on short signal segmentation and modulation signal bispectrum (MSB) slicing. This method initially separates short signals corresponding to individual cycles from the vibration signals based on encoder signals. Subsequently, MSB analysis is performed on each short signal to generate MSB carrier-slice spectra. The optimal carrier frequency and its corresponding modulation signal slice spectrum are determined based on the carrier-slice spectra. Finally, the MSB modulation signal slice spectra of the short signal set are averaged to obtain the overall average feature of the sliced spectra.
基金supported by the Program for New Century Excellent Talents in University, Ministry of Education (NCET-05-0803)
文摘The Radon-ambiguity transform (RAT), although efficient for detecting the linear frequency modulated signals (LFMs), is troubled by the energy accumulation of noise in low signal-to-noise ratio (SNR). A secondorder difference (SOD) method is proposed to treat with this problem. In the SOD method, the optimal search step and difference step are derived from the LFM rate resolution formula. The sharpness of the peaks of RAT is measured by curvature, and the sharpness, but not the magnitude of the peaks, is used to detect the LFMs. The SOD method removes the noise energy accumulation and reserves the drastically changing components integrally; thus, it improves the detection probability of LFMs in low SNR. The expected performance of the new method is verified by 100 Monte Carlo simulations.
基金supported by the National Natural Science Foundation of China (61631015, 61501354, 61501356, and 61573202)the Fundamental Research Funds of the Ministry of Education (7215433803)+5 种基金the Foundation of State Key Laboratory of Integrated Services Networks (ISN1101002)Higher School Subject Innovation Engineering Plan (B08038)Science and Technology Innovation Team Key Plan of Shaanxi Province (2016KCT-01)The Fundamental Research Funds of the Ministry of Education, China (Grant No. JB160101)The Key Laboratory Foundation of Ministry of Industry and Information Technology (KF20181912)China Postdoctoral Science Foundation (2018M631122)
文摘To boost the performance of 4-ary pulse amplitude modulated(PAM) at low signal-to-noise ratio(SNR), bistable stochastic resonance(BSR) system is introduced into digital communications system and get a reliable signal detection scheme. In this paper, we first analyse BSR system for different amplitudes of 4-ary PAM signals. The steadystate of the bistable system will be statistically distinct, and the feasibility of the proposed detection scheme is confirmed. On this basis, we present a detailed study on steady-state transitions of the BSR system, and an explicit expression of the bistable system parameters is derived. By setting the bistable system parameters, bistable system, 4-ary PAM signal, and noise reach the resonance state, and the BSR-based detection scheme is implemented. Moreover, we derive an analytical expression to calculate the symbol error rate(SER) of 4-ary PAM signals with the BSR-based detection under additive white Gaussian noise(AWGN). Finally, the simulation results validate that BSR-based detection scheme can improve the detection performance while efficiently reducing the symbol error rate.
基金Supported by the National High Technology Research and Development Program of China(863 Program)(2011AA1569)
文摘A new tracking algorithm is proposed aiming at the tracking problem in low bit signal-to- noise ratio (i. e. , Eb/N0 ) scenarios, in which the bit clock regenerated by bit synchronization loop decides loop update moment. The double frequency processing and non-coherent accumulation tech- nologies are applied to eliminate the impact of data polarity inversion, and then long time accumula- tion improves the input signal-to-noise ratio of discriminator. The frequency locked loop and phase locked loop constitute a carrier loop in parallel, which can meet the high dynamic demands. The ef- fectiveness of this algorithm has been corroborated by theoretical analysis, simulation and measure- ments, and the new tracking algorithm has been used in an aerospace engineering project successfully.
基金the Major Scientific andTechnical Project of Department of Science and Technology,Inner Mongolia in 2016(Strong Earthquake Track in the Short Stage and Integration Innovation of Stereoscopic Observation Technology in Space and Ground)
文摘In order to search for the seismic wave characteristics of low frequency signals in the Alxa Left Banner region,Inner Mongolia,the low frequency signals of seismic wave data are extracted from the earthquakes of MS5. 8 in 2015 and MS5. 0 in 2016 in this area. The results show that:① Before the MS5. 8 earthquake,the seismic stations located near the epicenter in Wuhai,Dongshengmiao,and Shizuishan recorded seismic waves that showed the phenomenon of spectrum shift from high to low frequency.② The low frequency signals recorded by different stations have obvious difference.③ According to the data recorded by the station closest to the epicenter,low-frequency signals were recorded about120 hours before the earthquake and had obvious anomalies. This may reflect slow slip before the earthquake.
文摘The essay mainly studies a system of low frequency signal′s measurement and the extraction of its characteristic quantity,introduces how matlab analyzes and extracts low frequency signal.MATLAB,a visual programming software,designs testing program for mechanic vibration signal,analyzes and identifies vibration signal.The collected data shows the effectiveness of the system.Based on XM121 modules,the testing system collects and analyzes single channel signal.
基金supported by the National Natural Science Foundation of China(Nos.81372076,51677146,51521065 and 51307133)the Sci-Tech Project of Shaanxi Province(No.2010K16-04)
文摘Low-temperature plasma(LTP) has shown great promise in wound healing,although the underlying mechanism remains poorly understood.In the present study,an argon atmospheric pressure plasma jet was employed to treat L929 murine fibroblasts cultured in vitro and skin wounds in BALB/c mice.The in vitro analysis revealed that treatment of fibroblasts with LTP for 15 s resulted in a significant increase in cell proliferation,secretion of epidermal growth factor(EGF) and transforming growth factor-β1(TGF-β1),production of intracellular reactive oxygen species(ROS),and the percentage of cells in S phase,protein expression of phosphorylated p65(P-p65) and cyclin D1,but a noted decrease in the protein expression of inhibitor kappa B(IκB).The in vivo experiments demonstrated that 30-s LTP treatment enhanced the number of fibroblasts and the ability of collagen synthesis,while 50-s treatment led to the opposite outcomes.These results suggested that LTP treatment promotes the fibroblast proliferation in wound healing by inducing the generation of ROS,upregulating the expression of P-p65,downregulating the expression of IκB,and activating the NF-κB signaling pathway and consequently altering cell cycle progression(increased DNA synthesis in S phage).
基金Sponsored by the National Natural Science Foundation of China (60843005)the Basic Research Foundation of Beijing Institute of Technology(20070142018)
文摘A low-power complementary metal oxide semiconductor(CMOS) operational amplifier (op-amp) for real-time signal processing of micro air vehicle (MAV) is designed in this paper.Traditional folded cascode architecture with positive channel metal oxide semiconductor(PMOS) differential input transistors and sub-threshold technology are applied under the low supply voltage.Simulation results show that this amplifier has significantly low power,while maintaining almost the same gain,bandwidth and other key performances.The power required is only 0.12 mW,which is applicable to low-power and low-voltage real-time signal acquisition and processing system.
基金Projects(50235030, 50505052) supported by the National Natural Science Foundation of China
文摘In order to investigate the regularity of metal magnetic signals of ferromagnetic materials under the effect of applied load, the static tensile test of Q235 steel and 18CrNiWA steel plate specimens were conducted and metal magnetic memory signals of specimens were measured during the test process. The influencing factors of metal magnetic memory signals and the relationship between axial applied load and signals were analyzed. The fracture and microstructure of the specimens were observed. The results show that the magnetic signals corresponding to the measured points change linearly approximately with increasing axial load. The microstructure of Q235 steel is ferrite and perlite, whereas that of 18CrNiWA steel is bainite and low-carbon martensite. The fracture of these two kinds of specimens is ductile rupture; carbon content of specimen materials and dislocation glide give much contribution to the characteristics of magnetic curves.