In order to satisfy increasingly greater demand for the performance of communication systems, a throughput efficient wireless system based on the extended binary phase shift keying （EBPSK） modulation is presented. S...In order to satisfy increasingly greater demand for the performance of communication systems, a throughput efficient wireless system based on the extended binary phase shift keying （EBPSK） modulation is presented. Simultaneously, corresponding analysis of power spectra is also given with a brief process. The optimal waveform is proposed without useful information loss, by removing linear spectra presenting periodic components. On this basis, the reasonable definition of bandwidth is discussed, which indicates that the EBPSK belongs to the category of the ultra narrow band （UNB） throughput-efficient communication. Meanwhile, the modulation parameters＇ effects on bandwidth, transmission rate and transmission performance are analyzed. Results illustrate the validity of theoretical analysis and spectrum optimization. Results also prove that this UNB system can obtain good bit error rate （BER） performance with high spectra efficiency.展开更多
The identification of the inter-electrode gap size in the high frequency group pulse micro-electrochemical machining （HGPECM） is mainly discussed. The auto-regressive（AR） model of group pulse current flowing acros...The identification of the inter-electrode gap size in the high frequency group pulse micro-electrochemical machining （HGPECM） is mainly discussed. The auto-regressive（AR） model of group pulse current flowing across the cathode and the anode are created under different situations with different processing parameters and inter-electrode gap size. The AR model based on the current signals indicates that the order of the AR model is obviously different relating to the different processing conditions and the inter-electrode gap size; Moreover, it is different about the stability of the dynamic system, i.e. the white noise response of the Green＇s function of the dynamic system is diverse. In addition, power spectrum method is used in the analysis of the dynamic time series about the current signals with different inter-electrode gap size, the results show that there exists a strongest power spectrum peak, characteristic power spectrum（CPS）, to the current signals related to the different inter-electrode gap size in the range of 0～5 kHz. Therefore, the CPS of current signals can implement the identification of the inter-electrode gap.展开更多
Understanding the physical features of the flow noise for an axisymmetric body is important for improving the performance of a sonar mounted on an underwater platform. Analytical calculation and numerical analysis of ...Understanding the physical features of the flow noise for an axisymmetric body is important for improving the performance of a sonar mounted on an underwater platform. Analytical calculation and numerical analysis of the physical features of the flow noise for an axisymmetric body are presented and a simulation scheme for the noise correlation on the hydrophones is given. It is shown that the numerical values of the flow noise coincide well with the analytical values. The main physical features of flow noise are obtained. The flow noises of two different models are compared and a model with a rather optimal fore-body shape is given. The flow noise in horizontal symmetry profile of the axisymmetric body is non-uniform, but it is omni-directional and has little difference in the cross section of the body. The loss of noise diffraction has a great effect on the flow noise from boundary layer transition. Meanwhile, based on the simulation, the noise power level increases with velocity to approximately the fifth power at high frequencies, which is consistent with the experiment data reported in the literature. Furthermore, the flow noise received by the acoustic array has lower correlation at a designed central frequency, which is important for sonar system design.展开更多
By using the technique for evolutionary power spectrum proposed by Nakayama and with reference to the Kameda formula, an evolutionary spectrum prediction model for given earthquake magnitude and distance is establishe...By using the technique for evolutionary power spectrum proposed by Nakayama and with reference to the Kameda formula, an evolutionary spectrum prediction model for given earthquake magnitude and distance is established based on the 80 near-source acceleration records at rock surface with large magnitude from the ground motion database of western U.S.. Then a new iteration method is developed for generation of random accelerograms non-stationary both in amplitude and frequency which are compatible with target evolutionary spectrum. The phase spectra of those simulated accelerograms are also non-stationary in time and frequency domains since the interaction between amplitude and phase angle has been considered during the generation. Furthermore, the sign of the phase spectrum increment is identified to accelerate the iteration. With the proposed statistical model for predicting evolutionary power spectra and the new method for generating compatible time history, the artificial random earthquake accelerograms non-stationary both in amplitude and frequency for certain magnitude and distance can be provided.展开更多
Based on the measurement of one-dimensional （1D） optical path difference （OPD） of the supersonic turbulent bound- ary layer, an analytical form for the power spectrum of the two-dimensional （2D） OPD is obtained ...Based on the measurement of one-dimensional （1D） optical path difference （OPD） of the supersonic turbulent bound- ary layer, an analytical form for the power spectrum of the two-dimensional （2D） OPD is obtained with its structure function and under the locally homogeneous isotropic assumption. The universality of this spectrum is argued, and its validity is checked by the comparison with experimental result. The potential applications of this model in theoretical and numerical studies are emphasized. Another contribution of this work is around the application of correlation function to analyzing the statistics of OPD. Based on our results and other results published elsewhere, we show that the OPD is often not stationary, and one should be cautious about using this tool.展开更多
In a drilling process, the power spectrum of the drilling force is related tothe tool wear and is widely applied in the monitoring of tool wear. But the feature extraction andidentification of the power spectrum have ...In a drilling process, the power spectrum of the drilling force is related tothe tool wear and is widely applied in the monitoring of tool wear. But the feature extraction andidentification of the power spectrum have always been an unresolved difficult problem. This papersolves it through decomposition of the power spectrum in multilayers using wavelet transform andextraction of the low frequency decomposition coefficient as the envelope information of the powerspectrum. Intelligent identification of the tool wear status is achieved in the drilling processthrough fusing the wavelet decomposition coefficient of the power spectrum by using a BP (BackPropagation) neural network. The experimental results show that the features of the power spectrumcan be extracted efficiently through this method, and the trained neural networks show highidentification precision and the ability of extension.展开更多
Local field potential(LFP) signals of the rat hippocampus were recorded under noninvasive focused ultrasound stimulation(FUS) with different ultrasonic powers. The LFP mean absolute power was calculated with the Welch...Local field potential(LFP) signals of the rat hippocampus were recorded under noninvasive focused ultrasound stimulation(FUS) with different ultrasonic powers. The LFP mean absolute power was calculated with the Welch algorithm at the delta, theta, alpha, beta, and gamma frequency bands. The experimental results demonstrate that the LFP mean absolute power at different frequency bands increases as the ultrasound power increases.展开更多
The period-3 behaviors of 105 exons from 20 genes in human were studied by Fourier power spectrum. The results indicated that not all exons show the period-3 behavior. The exons were adjusted in order to make them acc...The period-3 behaviors of 105 exons from 20 genes in human were studied by Fourier power spectrum. The results indicated that not all exons show the period-3 behavior. The exons were adjusted in order to make them accord with the order of the protein translated, and we found that the period-3 character is relation to the length of exons and the bases distribution in the three codon position. Furthermore, as long as the exons with period-3 behavior accord with the order of protein translated, they would exhibit the synonymous codons usage preference, and the codons with g/c at the third position are used in higher frequency. The results are significant to the gene prediction and the research on the introns.展开更多
The relationship between hippocampal electroencephalogram(EEG)power spectrum and the extinction of addiction memory was investigated.Forty KM mice(Kunming mice)that had successfully established morphine(MOR)-condition...The relationship between hippocampal electroencephalogram(EEG)power spectrum and the extinction of addiction memory was investigated.Forty KM mice(Kunming mice)that had successfully established morphine(MOR)-conditioned place preference(CPP)were divided into four groups:saline-training extinction(SAL-TE),SAL-natural extinction(SAL-NE),MORTE,MOR-NE,for extinction treatment and EEG recording in the dorsal and ventral hippocampus(DH/VH).Results show that the CPP score of MOR-TE significantly decreased and the total,βandγbands power spectrum of MOR-TE was suppressed.Notably,the total power from the VH was more correlated with the extinction method,and the TE total power was always lower than NE in SAL or MOR group.Naloxone enhanced the EEG total power and all bands(DH)orβandγbands(VH)power in the SAL group.However,in the MOR-TE group,onlyβandγbands power in VH increased(P<0.05).The results suggest that TE can promote the extinction of opiate addictive memory more effectively than NE,and the extinction of MOR-CPP may have a stronger correlation with changes of VH-EEG power spectrum.展开更多
It is important to extract texture feature from the ground-base cloud image for cloud type automatic detection.In this paper,a new method is presented to capture the contour edge,texture and geometric structure of clo...It is important to extract texture feature from the ground-base cloud image for cloud type automatic detection.In this paper,a new method is presented to capture the contour edge,texture and geometric structure of cloud images by using Contourlet and the power spectrum analysis algorithm.More abundant texture information is extracted.Cloud images can be obtained a multiscale and multidirection decomposition.The coefficient matrix from Contourlet transform of ground nephogram is calculated.The energy,mean and variance characteristics calculated from coefficient matrix are composed of the feature information.The frequency information of the data series from the feature vector values is obtained by the power spectrum analysis.Then Support Vector Machines(SVM)classifier is used to classify according to the frequency information of the trend graph of data series.It is shown that altocumulus and stratus with different texture frequencies can be effectively recognized and further subdivided the types of clouds.展开更多
When one applies the wavelet transform to analyze finite-length time series, discontinuities at the data boundaries will distort its wavelet power spectrum in some regions which are defined as a wavelength-dependent c...When one applies the wavelet transform to analyze finite-length time series, discontinuities at the data boundaries will distort its wavelet power spectrum in some regions which are defined as a wavelength-dependent cone of influence （COI）. In the COI, significance tests are unreliable. At the same time, as many time series are short and noisy, the COI is a serious limitation in wavelet analysis of time series. In this paper, we will give a method to reduce boundary effects and discover significant frequencies in the COI. After that, we will apply our method to analyze Greenland winter temperature and Baltic sea ice. The new method makes use of line removal and odd extension of the time series. This causes the derivative of the series to be continuous （unlike the case for other padding methods）. This will give the most reasonable padding methodology if the time series being analyzed has red noise characteristics.展开更多
The signals generated by electromagnetic flow sensors used for slurry fluids are often affected by noise interference produced by interaction with the slurry itself.In this study,the power spectrum characteristics of ...The signals generated by electromagnetic flow sensors used for slurry fluids are often affected by noise interference produced by interaction with the slurry itself.In this study,the power spectrum characteristics of the signal are studied,and an attempt is made to determine the relationship between the characteristics of the related noise and the velocity and concentration of the slurry fluid.Dedicated experiments are conducted and the related power spectrum curve is obtained processing the signal measured by the sensor with Matlab.Numerical simulations are also carried out in the frame of an Eulerian approach in order get additional insights into the considered problem through comparison with the experimental results.The following conclusions are drawn:(1)The intensity of noise is directly proportional to the number of solid particles colliding with the electrode of the electromagnetic flow sensor per unit time,and to the square of the average velocity of the flow layer near the pipe wall.(2)With an increase in the slurry noise intensity,the power spectrum curve shifts upward in the logarithmic coordinate system(and vice versa).展开更多
Blind image quality assessment(BIQA) can assess the perceptual quality of a distorted image without a prior knowledge of its reference image or distortion type. In this paper, a novel BIQA model is developed in wavele...Blind image quality assessment(BIQA) can assess the perceptual quality of a distorted image without a prior knowledge of its reference image or distortion type. In this paper, a novel BIQA model is developed in wavelet domain. Considering the multi-resolution and band-passing characteristics of discrete wavelet transform(DWT), an improvement over the power spectrum is put forward, i.e., dubbed wavelet power spectrum(WPS)estimation. Then, the concept of directional WPS is applied to simplify the calculation. Moreover, a rotationally symmetric modulation transfer function(MTF) of human visual system(HVS) is integrated as a filter, which makes the metric to be consistent with the human vision perception and more discriminative. Experiments are conducted on the LIVE databases and three other databases, and the results show that the proposed metric is highly correlated with subjective evaluations and it competes well with other state-of-the-art metrics in terms of effectiveness and robustness.展开更多
The paper proposed the research and implement of text similarity system based on power spectrum analysis. It is not difficult to imagine that the signals of brain are closely linked with writing process. So we build t...The paper proposed the research and implement of text similarity system based on power spectrum analysis. It is not difficult to imagine that the signals of brain are closely linked with writing process. So we build text modeling and set pulse signal function to get the power spectrum of the text. The specific detail is getting power spectrum from economic field to build spectral library, and then using the method of power spectrum matching algorithm to judge whether the test text belonged to the economic field. The method made text similarity system finish the function of text intelligent classification efficiently and accurately.展开更多
Developing a comprehensive model of the early universe that describes events and conditions prior to recombination has proved difficult. Using a new approach, we express Heisenberg’s uncertainty principle in terms of...Developing a comprehensive model of the early universe that describes events and conditions prior to recombination has proved difficult. Using a new approach, we express Heisenberg’s uncertainty principle in terms of measures and counts of those measures to resolve an expression consisting entirely of counts. The description allows us to resolve explicit values for discrete measures. With these values, we present new expressions describing the earliest epoch and the transition event that initiates expansion. We determine the quantity, age, density, and temperature of the cosmic microwave background (CMB). Moreover, we approach the CMB power spectrum anew, describing each mass/energy distribution, its physical significance, its peak temperature, and the effects of relativity. We do not engage in fitting or modification of the existing laws of physics. The approach is classical and correlates both quantum and cosmological phenomena with descriptive expressions that are measurable, verifiable, and falsifiable.展开更多
Spectrum sensing is an essential component to realize the cognitive radio, and the requirement for real-time spectrum sensing in the case of lacking prior information, fading channel, and noise uncertainty, indeed pos...Spectrum sensing is an essential component to realize the cognitive radio, and the requirement for real-time spectrum sensing in the case of lacking prior information, fading channel, and noise uncertainty, indeed poses a major challenge to the classical spectrum sensing algorithms. Based on the stochastic properties of scalar transformation of power spectral density（PSD）, a novel spectrum sensing algorithm, referred to as the power spectral density split cancellation method（PSC）, is proposed in this paper. The PSC makes use of a scalar value as a test statistic, which is the ratio of each subband power to the full band power. Besides, by exploiting the asymptotic normality and independence of Fourier transform,the distribution of the ratio and the mathematical expressions for the probabilities of false alarm and detection in different channel models are derived. Further, the exact closed-form expression of decision threshold is calculated in accordance with Neyman–Pearson criterion. Analytical and simulation results show that the PSC is invulnerable to noise uncertainty,and can achive excellent detection performance without prior knowledge in additive white Gaussian noise and flat slow fading channels. In addition, the PSC benefits from a low computational cost, which can be completed in microseconds.展开更多
Background Epilepsy is one of the common clinical disorders with comorbid anxiety and depression that severely afects their quality of life and increases their suicidality,while screening for anxiety and depression cu...Background Epilepsy is one of the common clinical disorders with comorbid anxiety and depression that severely afects their quality of life and increases their suicidality,while screening for anxiety and depression currently lacks objective identifers.This study aimed to analyze the characteristics of the electroencephalogram(EEG)power spectrum in patients with epilepsy with comorbid anxiety and depression,utilizing resting EEG data.Methods Resting EEG data were collected under standard conditions from two groups:patients with epilepsy comorbid with anxiety and depression(n=42)and patients without comorbidities(n=45).EEG power was calculated using data processing with EEGLAB and MATLAB.This study compared the absolute and relative powers of theδ,θ,α,β,andγfrequency bands,as well as the values of(δ+θ)/(α+β),between the two groups.Additionally,the correlation between the EEG power of each frequency band and anxiety and depression scores was analyzed.Results 1)Among individuals with epilepsy comorbid with anxiety and depression,lower absolute power ofδ,α,andθat specifc sites was observed(P<0.05),along with lower relative power ofθat certain sites(P<0.05).Conversely,higher relative power ofβandγat specifc sites was noted in those with comorbidities(P<0.05).2)There was no statistically signifcant diference in the values of(δ+θ)/(α+β)between the two groups(P>0.05).3)Depression scores exhibited a negative correlation withθabsolute power at the T3 and T4 sites(P<0.05),while showing a positive correlation withβrelative power at the C4 and T6 sites(P<0.05).Anxiety scores displayed a positive correlation withβrelative power at the F4,C3,C4 and T6 sites andγrelative power at F8 site(P<0.05).Conclusions The fndings suggest that comorbid anxiety and depression may impact resting EEG power spectra in individuals with epilepsy,particularly in regions exhibiting altered network connectivity.Furthermore,a positive correlation was observed between anxiety and depression scores andβrelative power in the right central and right posterior temporal regions,indicating potential screening utility.展开更多
Airborne pulse radar and communication systems are essential for precise detection and collision avoidance,ensuring that aircraft operate safely and efficiently.A major challenge in spectrum sharing is the allocation ...Airborne pulse radar and communication systems are essential for precise detection and collision avoidance,ensuring that aircraft operate safely and efficiently.A major challenge in spectrum sharing is the allocation of resources in both the time and frequency domains,aiming to minimize inter-system interference as the available spectrum fluctuates over time.In this paper,regarding maximization of detection probability and spectrum utilization efficiency as two fundamental objectives,a novel Dynamic Spectrum and Power Allocation based on Genetic Algorithm(GA-DSPA)model is proposed,which dynamically allocates communication channel frequency and power under the constraints of pulse radar detection probability and signal-to-interferenceplus-noise ratio of communication.To solve this bi-objective model,a non-dominated sortingbased multi-objective genetic algorithm is developed.A novel environment perception strategy and offspring sorting technique based on radar echoes are integrated into the optimization framework.Simulation results indicate that by integrating environmental monitoring mechanisms and dynamic adaptation strategies,the proposed method effectively tracks the evolving Paretooptimal Fronts(Po Fs),thereby ensuring optimal performance for both co-located pulse radar and communication systems.Hardware test results confirm that within the GA-DSPA framework,the pulse radar achieves higher detection probabilities under identical conditions,while the communication system realizes increased average throughput.展开更多
Understanding the photon number statistics of a quantum emitter(QE)interacting with complex photonic environments is fundamental to advances in quantum optics and nanophotonics.We introduce a general theoretical frame...Understanding the photon number statistics of a quantum emitter(QE)interacting with complex photonic environments is fundamental to advances in quantum optics and nanophotonics.We introduce a general theoretical framework for calculating the modal photon number density spectrum(MPNDS)in arbitrary dielectric structures with an embedded two-level QE.We validate our approach by investigating a system composed of a two-level QE and a photonic crystal(PhC)slab with an L3 cavity and a waveguide,finding that the MPNDS exhibits significant changes in both waveguide and background radiative channels as the interaction between the QE and modal field transitions from weak coupling to strong coupling.We observe that the number of photons guided along the waveguide shows a strong dependence on the QE’s transition frequency and transition dipole moment,but demonstrates robustness to the transition dipole moment when the transition frequency approaches the waveguide cutoff frequency.Our work allows for the determination and tailoring of light emission characteristics across diverse radiative channels in complex photonic environments.展开更多
Precise measurement of betatron tune is required for good operating condition of CSNS RCS. The fractional part of betatron tune is important and it can be measured by analyzing the signals of beam position from the ap...Precise measurement of betatron tune is required for good operating condition of CSNS RCS. The fractional part of betatron tune is important and it can be measured by analyzing the signals of beam position from the appointed BPM. Usually these signals are contaminated during the acquisition process, therefore several power spectrum methods are used to improve the frequency resolution. In this article classical and modern power spectrum methods are used. In order to compare their performance, the results of simulation data and IQT data from J-PARC RCS are discussed, It is shown that modern power spectrum estimation has better performance than the classical ones, though the calculation is more complex.展开更多
基金The National Natural Science Foundation of China(No.60472054)the Natural Science Foundation of Jiangsu Province(No.BK2007103)
文摘In order to satisfy increasingly greater demand for the performance of communication systems, a throughput efficient wireless system based on the extended binary phase shift keying （EBPSK） modulation is presented. Simultaneously, corresponding analysis of power spectra is also given with a brief process. The optimal waveform is proposed without useful information loss, by removing linear spectra presenting periodic components. On this basis, the reasonable definition of bandwidth is discussed, which indicates that the EBPSK belongs to the category of the ultra narrow band （UNB） throughput-efficient communication. Meanwhile, the modulation parameters＇ effects on bandwidth, transmission rate and transmission performance are analyzed. Results illustrate the validity of theoretical analysis and spectrum optimization. Results also prove that this UNB system can obtain good bit error rate （BER） performance with high spectra efficiency.
基金This project is supported by the 10th Five-year Plan Pre-research Project Foundation of China Weapon Industry Company, China(No.42001080701).
文摘The identification of the inter-electrode gap size in the high frequency group pulse micro-electrochemical machining （HGPECM） is mainly discussed. The auto-regressive（AR） model of group pulse current flowing across the cathode and the anode are created under different situations with different processing parameters and inter-electrode gap size. The AR model based on the current signals indicates that the order of the AR model is obviously different relating to the different processing conditions and the inter-electrode gap size; Moreover, it is different about the stability of the dynamic system, i.e. the white noise response of the Green＇s function of the dynamic system is diverse. In addition, power spectrum method is used in the analysis of the dynamic time series about the current signals with different inter-electrode gap size, the results show that there exists a strongest power spectrum peak, characteristic power spectrum（CPS）, to the current signals related to the different inter-electrode gap size in the range of 0～5 kHz. Therefore, the CPS of current signals can implement the identification of the inter-electrode gap.
基金Project supported by the National Natural Science Foundational of China (Grant No. 10774119)the Program for New Century Excellent Talents in University, China (Grant No. NCET-08-0455)+1 种基金the Natural Science Foundation of Shaanxi Province of China (Grant No. SJ08F07)the Foundation of National Laboratory of Acoustic and the Foundation for Fundamental Research of Northwestern Polytechnic University, China (Grant No. 2007004)
文摘Understanding the physical features of the flow noise for an axisymmetric body is important for improving the performance of a sonar mounted on an underwater platform. Analytical calculation and numerical analysis of the physical features of the flow noise for an axisymmetric body are presented and a simulation scheme for the noise correlation on the hydrophones is given. It is shown that the numerical values of the flow noise coincide well with the analytical values. The main physical features of flow noise are obtained. The flow noises of two different models are compared and a model with a rather optimal fore-body shape is given. The flow noise in horizontal symmetry profile of the axisymmetric body is non-uniform, but it is omni-directional and has little difference in the cross section of the body. The loss of noise diffraction has a great effect on the flow noise from boundary layer transition. Meanwhile, based on the simulation, the noise power level increases with velocity to approximately the fifth power at high frequencies, which is consistent with the experiment data reported in the literature. Furthermore, the flow noise received by the acoustic array has lower correlation at a designed central frequency, which is important for sonar system design.
基金Key Program of the National Natural Science Foundation of China (90510017)
文摘By using the technique for evolutionary power spectrum proposed by Nakayama and with reference to the Kameda formula, an evolutionary spectrum prediction model for given earthquake magnitude and distance is established based on the 80 near-source acceleration records at rock surface with large magnitude from the ground motion database of western U.S.. Then a new iteration method is developed for generation of random accelerograms non-stationary both in amplitude and frequency which are compatible with target evolutionary spectrum. The phase spectra of those simulated accelerograms are also non-stationary in time and frequency domains since the interaction between amplitude and phase angle has been considered during the generation. Furthermore, the sign of the phase spectrum increment is identified to accelerate the iteration. With the proposed statistical model for predicting evolutionary power spectra and the new method for generating compatible time history, the artificial random earthquake accelerograms non-stationary both in amplitude and frequency for certain magnitude and distance can be provided.
基金Project supported by the National Natural Science Foundation of China(Grant No.61008037)the National Basic Research Program of China(Grant No.2009CB724100)
文摘Based on the measurement of one-dimensional （1D） optical path difference （OPD） of the supersonic turbulent bound- ary layer, an analytical form for the power spectrum of the two-dimensional （2D） OPD is obtained with its structure function and under the locally homogeneous isotropic assumption. The universality of this spectrum is argued, and its validity is checked by the comparison with experimental result. The potential applications of this model in theoretical and numerical studies are emphasized. Another contribution of this work is around the application of correlation function to analyzing the statistics of OPD. Based on our results and other results published elsewhere, we show that the OPD is often not stationary, and one should be cautious about using this tool.
文摘In a drilling process, the power spectrum of the drilling force is related tothe tool wear and is widely applied in the monitoring of tool wear. But the feature extraction andidentification of the power spectrum have always been an unresolved difficult problem. This papersolves it through decomposition of the power spectrum in multilayers using wavelet transform andextraction of the low frequency decomposition coefficient as the envelope information of the powerspectrum. Intelligent identification of the tool wear status is achieved in the drilling processthrough fusing the wavelet decomposition coefficient of the power spectrum by using a BP (BackPropagation) neural network. The experimental results show that the features of the power spectrumcan be extracted efficiently through this method, and the trained neural networks show highidentification precision and the ability of extension.
基金supported by the National Natural Science Foundation of China(Grant No.61273063)China Postdoctoral Science Foundation(Grant No.2013M540215)the Natural Science Foundation of Hebei Province,China(Grant No.F2014203161)
文摘Local field potential(LFP) signals of the rat hippocampus were recorded under noninvasive focused ultrasound stimulation(FUS) with different ultrasonic powers. The LFP mean absolute power was calculated with the Welch algorithm at the delta, theta, alpha, beta, and gamma frequency bands. The experimental results demonstrate that the LFP mean absolute power at different frequency bands increases as the ultrasound power increases.
基金This work was supported by the National Natural Science Foundation of China(Grants 20475068)the Natural Science Foundation of Guangdong Province(Contact No.031577)the Opening Foundation of State Key Laboratory of Chem/Biosensing and Chemometrics of Hunan University(2003).
文摘The period-3 behaviors of 105 exons from 20 genes in human were studied by Fourier power spectrum. The results indicated that not all exons show the period-3 behavior. The exons were adjusted in order to make them accord with the order of the protein translated, and we found that the period-3 character is relation to the length of exons and the bases distribution in the three codon position. Furthermore, as long as the exons with period-3 behavior accord with the order of protein translated, they would exhibit the synonymous codons usage preference, and the codons with g/c at the third position are used in higher frequency. The results are significant to the gene prediction and the research on the introns.
基金the National Natural Science Foundation of China(31760278)NHC Key Laboratory of Drug Addiction Medicine of Kunming Medical University(2020DAMOP-002)。
文摘The relationship between hippocampal electroencephalogram(EEG)power spectrum and the extinction of addiction memory was investigated.Forty KM mice(Kunming mice)that had successfully established morphine(MOR)-conditioned place preference(CPP)were divided into four groups:saline-training extinction(SAL-TE),SAL-natural extinction(SAL-NE),MORTE,MOR-NE,for extinction treatment and EEG recording in the dorsal and ventral hippocampus(DH/VH).Results show that the CPP score of MOR-TE significantly decreased and the total,βandγbands power spectrum of MOR-TE was suppressed.Notably,the total power from the VH was more correlated with the extinction method,and the TE total power was always lower than NE in SAL or MOR group.Naloxone enhanced the EEG total power and all bands(DH)orβandγbands(VH)power in the SAL group.However,in the MOR-TE group,onlyβandγbands power in VH increased(P<0.05).The results suggest that TE can promote the extinction of opiate addictive memory more effectively than NE,and the extinction of MOR-CPP may have a stronger correlation with changes of VH-EEG power spectrum.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.41775165,41305137,41706109,41475022).
文摘It is important to extract texture feature from the ground-base cloud image for cloud type automatic detection.In this paper,a new method is presented to capture the contour edge,texture and geometric structure of cloud images by using Contourlet and the power spectrum analysis algorithm.More abundant texture information is extracted.Cloud images can be obtained a multiscale and multidirection decomposition.The coefficient matrix from Contourlet transform of ground nephogram is calculated.The energy,mean and variance characteristics calculated from coefficient matrix are composed of the feature information.The frequency information of the data series from the feature vector values is obtained by the power spectrum analysis.Then Support Vector Machines(SVM)classifier is used to classify according to the frequency information of the trend graph of data series.It is shown that altocumulus and stratus with different texture frequencies can be effectively recognized and further subdivided the types of clouds.
基金partially supported by the National Key Science Program for Global Change Research (Grant no.2010CB950504)the National High-Technology Research & Development Program of China (863 Program,Grant no.2010AA012305)+2 种基金the National Natural Science Foundation of China(Grant no.41076125)the Fundamental Research Funds for the Central Universities (Key Program)the Polar Climate and Environment Key Laboratory
文摘When one applies the wavelet transform to analyze finite-length time series, discontinuities at the data boundaries will distort its wavelet power spectrum in some regions which are defined as a wavelength-dependent cone of influence （COI）. In the COI, significance tests are unreliable. At the same time, as many time series are short and noisy, the COI is a serious limitation in wavelet analysis of time series. In this paper, we will give a method to reduce boundary effects and discover significant frequencies in the COI. After that, we will apply our method to analyze Greenland winter temperature and Baltic sea ice. The new method makes use of line removal and odd extension of the time series. This causes the derivative of the series to be continuous （unlike the case for other padding methods）. This will give the most reasonable padding methodology if the time series being analyzed has red noise characteristics.
基金National Key Research and Development Program of China Subproject(No.2016YFD0700103)Natural Science Foundation of Henan(Nos.202300410124&19HASTIT021)+1 种基金Key Research and Development Program of Yunnan Province(No.2018ZC001)the National Natural Science foundation of China under Grant No.61801288.
文摘The signals generated by electromagnetic flow sensors used for slurry fluids are often affected by noise interference produced by interaction with the slurry itself.In this study,the power spectrum characteristics of the signal are studied,and an attempt is made to determine the relationship between the characteristics of the related noise and the velocity and concentration of the slurry fluid.Dedicated experiments are conducted and the related power spectrum curve is obtained processing the signal measured by the sensor with Matlab.Numerical simulations are also carried out in the frame of an Eulerian approach in order get additional insights into the considered problem through comparison with the experimental results.The following conclusions are drawn:(1)The intensity of noise is directly proportional to the number of solid particles colliding with the electrode of the electromagnetic flow sensor per unit time,and to the square of the average velocity of the flow layer near the pipe wall.(2)With an increase in the slurry noise intensity,the power spectrum curve shifts upward in the logarithmic coordinate system(and vice versa).
文摘Blind image quality assessment(BIQA) can assess the perceptual quality of a distorted image without a prior knowledge of its reference image or distortion type. In this paper, a novel BIQA model is developed in wavelet domain. Considering the multi-resolution and band-passing characteristics of discrete wavelet transform(DWT), an improvement over the power spectrum is put forward, i.e., dubbed wavelet power spectrum(WPS)estimation. Then, the concept of directional WPS is applied to simplify the calculation. Moreover, a rotationally symmetric modulation transfer function(MTF) of human visual system(HVS) is integrated as a filter, which makes the metric to be consistent with the human vision perception and more discriminative. Experiments are conducted on the LIVE databases and three other databases, and the results show that the proposed metric is highly correlated with subjective evaluations and it competes well with other state-of-the-art metrics in terms of effectiveness and robustness.
文摘The paper proposed the research and implement of text similarity system based on power spectrum analysis. It is not difficult to imagine that the signals of brain are closely linked with writing process. So we build text modeling and set pulse signal function to get the power spectrum of the text. The specific detail is getting power spectrum from economic field to build spectral library, and then using the method of power spectrum matching algorithm to judge whether the test text belonged to the economic field. The method made text similarity system finish the function of text intelligent classification efficiently and accurately.
文摘Developing a comprehensive model of the early universe that describes events and conditions prior to recombination has proved difficult. Using a new approach, we express Heisenberg’s uncertainty principle in terms of measures and counts of those measures to resolve an expression consisting entirely of counts. The description allows us to resolve explicit values for discrete measures. With these values, we present new expressions describing the earliest epoch and the transition event that initiates expansion. We determine the quantity, age, density, and temperature of the cosmic microwave background (CMB). Moreover, we approach the CMB power spectrum anew, describing each mass/energy distribution, its physical significance, its peak temperature, and the effects of relativity. We do not engage in fitting or modification of the existing laws of physics. The approach is classical and correlates both quantum and cosmological phenomena with descriptive expressions that are measurable, verifiable, and falsifiable.
基金Project supported by the National Natural Science Foundation of China(Grant No.61301179)the Doctorial Program Foundation of the Ministry of Education,China(Grant No.20110203110011)the 111 Project,China(Grant No.B08038)
文摘Spectrum sensing is an essential component to realize the cognitive radio, and the requirement for real-time spectrum sensing in the case of lacking prior information, fading channel, and noise uncertainty, indeed poses a major challenge to the classical spectrum sensing algorithms. Based on the stochastic properties of scalar transformation of power spectral density（PSD）, a novel spectrum sensing algorithm, referred to as the power spectral density split cancellation method（PSC）, is proposed in this paper. The PSC makes use of a scalar value as a test statistic, which is the ratio of each subband power to the full band power. Besides, by exploiting the asymptotic normality and independence of Fourier transform,the distribution of the ratio and the mathematical expressions for the probabilities of false alarm and detection in different channel models are derived. Further, the exact closed-form expression of decision threshold is calculated in accordance with Neyman–Pearson criterion. Analytical and simulation results show that the PSC is invulnerable to noise uncertainty,and can achive excellent detection performance without prior knowledge in additive white Gaussian noise and flat slow fading channels. In addition, the PSC benefits from a low computational cost, which can be completed in microseconds.
基金funded by the National Natural Science Foundation of China(82101527,32160190)the Science and Technology Project in Guizhou Province(Grant No.QKHJC-ZK[2021]No.408)the Science and Technology Foundation of the Guizhou Provincial Health Commission(gzwkj2021-026).
文摘Background Epilepsy is one of the common clinical disorders with comorbid anxiety and depression that severely afects their quality of life and increases their suicidality,while screening for anxiety and depression currently lacks objective identifers.This study aimed to analyze the characteristics of the electroencephalogram(EEG)power spectrum in patients with epilepsy with comorbid anxiety and depression,utilizing resting EEG data.Methods Resting EEG data were collected under standard conditions from two groups:patients with epilepsy comorbid with anxiety and depression(n=42)and patients without comorbidities(n=45).EEG power was calculated using data processing with EEGLAB and MATLAB.This study compared the absolute and relative powers of theδ,θ,α,β,andγfrequency bands,as well as the values of(δ+θ)/(α+β),between the two groups.Additionally,the correlation between the EEG power of each frequency band and anxiety and depression scores was analyzed.Results 1)Among individuals with epilepsy comorbid with anxiety and depression,lower absolute power ofδ,α,andθat specifc sites was observed(P<0.05),along with lower relative power ofθat certain sites(P<0.05).Conversely,higher relative power ofβandγat specifc sites was noted in those with comorbidities(P<0.05).2)There was no statistically signifcant diference in the values of(δ+θ)/(α+β)between the two groups(P>0.05).3)Depression scores exhibited a negative correlation withθabsolute power at the T3 and T4 sites(P<0.05),while showing a positive correlation withβrelative power at the C4 and T6 sites(P<0.05).Anxiety scores displayed a positive correlation withβrelative power at the F4,C3,C4 and T6 sites andγrelative power at F8 site(P<0.05).Conclusions The fndings suggest that comorbid anxiety and depression may impact resting EEG power spectra in individuals with epilepsy,particularly in regions exhibiting altered network connectivity.Furthermore,a positive correlation was observed between anxiety and depression scores andβrelative power in the right central and right posterior temporal regions,indicating potential screening utility.
基金co-supported by the National Natural Science Foundation of China(No.62293495)the National Key Research and Development Program of China(No.2023YFB3306900)the Academic Excellence Foundation of BUAA for ph.D Students,China。
文摘Airborne pulse radar and communication systems are essential for precise detection and collision avoidance,ensuring that aircraft operate safely and efficiently.A major challenge in spectrum sharing is the allocation of resources in both the time and frequency domains,aiming to minimize inter-system interference as the available spectrum fluctuates over time.In this paper,regarding maximization of detection probability and spectrum utilization efficiency as two fundamental objectives,a novel Dynamic Spectrum and Power Allocation based on Genetic Algorithm(GA-DSPA)model is proposed,which dynamically allocates communication channel frequency and power under the constraints of pulse radar detection probability and signal-to-interferenceplus-noise ratio of communication.To solve this bi-objective model,a non-dominated sortingbased multi-objective genetic algorithm is developed.A novel environment perception strategy and offspring sorting technique based on radar echoes are integrated into the optimization framework.Simulation results indicate that by integrating environmental monitoring mechanisms and dynamic adaptation strategies,the proposed method effectively tracks the evolving Paretooptimal Fronts(Po Fs),thereby ensuring optimal performance for both co-located pulse radar and communication systems.Hardware test results confirm that within the GA-DSPA framework,the pulse radar achieves higher detection probabilities under identical conditions,while the communication system realizes increased average throughput.
基金Project supported by the Basic and Applied Basic Research Project,Guangzhou Basic Research Plan(Grant No.202201011444).
文摘Understanding the photon number statistics of a quantum emitter(QE)interacting with complex photonic environments is fundamental to advances in quantum optics and nanophotonics.We introduce a general theoretical framework for calculating the modal photon number density spectrum(MPNDS)in arbitrary dielectric structures with an embedded two-level QE.We validate our approach by investigating a system composed of a two-level QE and a photonic crystal(PhC)slab with an L3 cavity and a waveguide,finding that the MPNDS exhibits significant changes in both waveguide and background radiative channels as the interaction between the QE and modal field transitions from weak coupling to strong coupling.We observe that the number of photons guided along the waveguide shows a strong dependence on the QE’s transition frequency and transition dipole moment,but demonstrates robustness to the transition dipole moment when the transition frequency approaches the waveguide cutoff frequency.Our work allows for the determination and tailoring of light emission characteristics across diverse radiative channels in complex photonic environments.
文摘Precise measurement of betatron tune is required for good operating condition of CSNS RCS. The fractional part of betatron tune is important and it can be measured by analyzing the signals of beam position from the appointed BPM. Usually these signals are contaminated during the acquisition process, therefore several power spectrum methods are used to improve the frequency resolution. In this article classical and modern power spectrum methods are used. In order to compare their performance, the results of simulation data and IQT data from J-PARC RCS are discussed, It is shown that modern power spectrum estimation has better performance than the classical ones, though the calculation is more complex.
