Energy resolution calibration is crucial for gamma-ray spectral analysis,as measured using a scintillation detector.A locally constrained regularization method was proposed to determine the resolution calibration para...Energy resolution calibration is crucial for gamma-ray spectral analysis,as measured using a scintillation detector.A locally constrained regularization method was proposed to determine the resolution calibration parameters.First,a Monte Carlo simulation model consistent with an actual measurement system was constructed to obtain the energy deposition distribution in the scintillation crystal.Subsequently,the regularization objective function is established based on weighted least squares and additional constraints.Additional constraints were designed using a special weighting scheme based on the incident gamma-ray energies.Subsequently,an intelligent algorithm was introduced to search for the optimal resolution calibration parameters by minimizing the objective function.The most appropriate regularization parameter was determined through mathematical experiments.When the regularization parameter was 30,the calibrated results exhibited the minimum RMSE.Simulations and test pit experiments were conducted to verify the performance of the proposed method.The simulation results demonstrate that the proposed algorithm can determine resolution calibration parameters more accurately than the traditional weighted least squares,and the test pit experimental results show that the R-squares between the calibrated and measured spectra are larger than 0.99.The accurate resolution calibration parameters determined by the proposed method lay the foundation for gamma-ray spectral processing and simulation benchmarking.展开更多
The three-dimensional spectral analysis method was applied to airglow data from September 2023 to August 2024 derivedfrom an OH airglow imager located at the Hejing station (42.79°N, 83.73°E) to study the pr...The three-dimensional spectral analysis method was applied to airglow data from September 2023 to August 2024 derivedfrom an OH airglow imager located at the Hejing station (42.79°N, 83.73°E) to study the propagation characteristics of gravity waves(GWs) over Northwest China. We found that obvious seasonal variations occur in the propagation of GWs. In spring, GWs mainlypropagate in the northeast direction. In summer and autumn, GWs mainly propagate in the north direction. However, GWs mainlypropagate in the south direction in winter. The direction of GW propagation in the zonal direction is controlled by the wind-filteringeffect, whereas the north–south meridional direction is mainly determined by the location of the wave source. We found that the averageenergy spectrum exhibits a 10%–20% higher intensity in summer and winter compared with spring and autumn. For the first time, wereport the seasonal variation characteristics of GWs over the inland areas of Northwest China, which is of great significance forunderstanding the regional distribution characteristics of GWs.展开更多
As a frequently occurred marine pollution phenomenon,red tides of water body due to eutrophication cause massive mortality of marine organisms and serious ecological problems.The early warning and prediction of red ti...As a frequently occurred marine pollution phenomenon,red tides of water body due to eutrophication cause massive mortality of marine organisms and serious ecological problems.The early warning and prediction of red tide outbreak can provide guidance to the coastal management,and is of great value to the aquaculture industry and marine environment protection.An approach for the risk assessment of red tide occurrence using spectral indices was made.The optimal spectral indices were explored from three candidates,namely two-band ratio(TBR)method,three-band spectral index(TBSI)method,and fluorescence baseline(FLB)method.The correlations between the spectral indices and the red tide occurrence were quantitatively evaluated through analysis of variance(ANOVA).The risk maps for the Beibu Gulf and the Bohai Bay in China were produced with the normalized spectral indices based on the multi-spectral observation from Sentinel-3 satellite.Results show that both TBR and TBSI values have significant correlations with the occurrences of red tide as the ANOVA results.TBSI illustrated correctly the risk of red tide occurrence in the risk maps and was the optimal spectral index offshore risk assessment of red tide.FLB method failed to recognize the high-risk regions and may not be the appropriate spectral index.The risk assessment method proposed in this study can provide early alarms on red tide occurrence and help timely the countermeasure against potential harms.展开更多
In order to overcome the shortcomings that the reconstructed spectral reflectance may be negative when using the classic principal component analysis （PCA）to reduce the dimensions of the multi-spectral data, a nonne...In order to overcome the shortcomings that the reconstructed spectral reflectance may be negative when using the classic principal component analysis （PCA）to reduce the dimensions of the multi-spectral data, a nonnegative constrained principal component analysis method is proposed to construct a low-dimensional multi-spectral space and accomplish the conversion between the new constructed space and the multispectral space. First, the reason behind the negative data is analyzed and a nonnegative constraint is imposed on the classic PCA. Then a set of nonnegative linear independence weight vectors of principal components is obtained, by which a lowdimensional space is constructed. Finally, a nonlinear optimization technique is used to determine the projection vectors of the high-dimensional multi-spectral data in the constructed space. Experimental results show that the proposed method can keep the reconstructed spectral data in [ 0, 1 ]. The precision of the space created by the proposed method is equivalent to or even higher than that by the PCA.展开更多
[ Objective] The paper was to operate the application and promotion of non-pesticide replacing high-toxic pesticides techniques in Kunming City, and to analyze its benefit. [ Method ] Through application and promotion...[ Objective] The paper was to operate the application and promotion of non-pesticide replacing high-toxic pesticides techniques in Kunming City, and to analyze its benefit. [ Method ] Through application and promotion of frequency trembler grid lamps, sticking plate trapping technology, construction of treatment ponds for field waste vegetable leaves, standardized （accurate） cultivation techniques, cultivation techniques of disease-resistant varieties and diverse cultivation technologies, the promotion benefit of non-pesticide replacing high-toxic pesticides techniques was comprehensively investigated and evaluated. [ Result ] The appli- cation and promotion area of non-pesticide replacing high-toxic pesticides techniques in Kunming City during 2006 -2010 reached 94 667 hm2. The investigation on control efforts and quantitative analysis of cost/benefit showed that the beneficial result of application and promotion of non-pesticide replacing high-toxic pesticides techniques was higher than the direct benefit of application and promotion of traditional pesticide replacing techniques. This improvement innovated the traditional pesticide replacing method in replacement work of high-toxic pesticides, reducing the usage volume of pesticide in Kunming City. [ Conclusion] The application and promotion of non-pesticide replacing high-toxic pesticides techniques improved the economic, social and ecological benefit of replacement work of high-toxic pesticides, protected the agricultural ecological environment and promoted the sustainable development of agricultural production.展开更多
Abstract The continuously rotating detonation engine （CRDE） is a new concept of engines for air- craft and spacecraft. Quasi-stable continuously rotating detonation （CRD） can be observed in an annular combustion c...Abstract The continuously rotating detonation engine （CRDE） is a new concept of engines for air- craft and spacecraft. Quasi-stable continuously rotating detonation （CRD） can be observed in an annular combustion chamber, but the sustaining, stabilizing and adjusting mechanisms are not yet clear. To learn more deeply into the CRDE, experimental studies have been carried out to inves- tigate hydrogen-oxygen CRDE. Pressure histories are obtained during each shot, which show that stable CRD waves are generated in the combustor, when feeding pressures are higher than 0.5 MPa for fuel and oxidizer, respectively. Each shot can keep running as long as fresh gas feeding main- tains. Close-up of the pressure history shows the repeatability of pressure peaks and indicates the detonation velocity in hydrogen-oxygen CRD, which proves the success of forming a stable CRD in the annular chamber. Spectrum of the pressure history matches the close-up analysis and confirms the CRD. It also shows multi-wave phenomenon and affirms the fact that in this case a single detonation wave is rotating in the annulus. Moreover, oscillation phenomenon is found in pressure peaks and a self-adjusting mechanism is proposed to explain the phenomenon.展开更多
The spectral methods and ice-induced fatigue analysis are discussed based on Miner＇s linear cumulative fatigue hypothesis and S-N curve data. According to the long-term data of full-scale tests on the platforms in th...The spectral methods and ice-induced fatigue analysis are discussed based on Miner＇s linear cumulative fatigue hypothesis and S-N curve data. According to the long-term data of full-scale tests on the platforms in the Bohai Sea, the ice force spectrum of conical structures and the fatigue environmental model are established. Moreover, the finite element model of JZ20-2MSW platform, an example of ice-induced fatigue analysis, is built with ANSYS software. The mode analysis and dynamic analysis in frequency domain under all kinds of ice fatigue work conditions are carded on, and the fatigue life of the structure is estimated in detail. The methods in this paper can be helpful in ice-induced fatigue analysis of ice-resistant platforms.展开更多
Response spectral moments are useful for system reliability analysis.Usually,spectral mo- ments are calculated by the frequency domain method.Based on the time domain modal analysis of random vibrations,the authors pr...Response spectral moments are useful for system reliability analysis.Usually,spectral mo- ments are calculated by the frequency domain method.Based on the time domain modal analysis of random vibrations,the authors present a new method for calculating response spectral moments through response correlation functions.The method can be applied to both classical and non-classical damping cases and to three kinds of random excitations,i.e.,white noise,band-limited white noise, and filtered white noise.展开更多
In modern transportation,pavement is one of the most important civil infrastructures for the movement of vehicles and pedestrians.Pavement service quality and service life are of great importance for civil engineers a...In modern transportation,pavement is one of the most important civil infrastructures for the movement of vehicles and pedestrians.Pavement service quality and service life are of great importance for civil engineers as they directly affect the regular service for the users.Therefore,monitoring the health status of pavement before irreversible damage occurs is essential for timely maintenance,which in turn ensures public transportation safety.Many pavement damages can be detected and analyzed by monitoring the structure dynamic responses and evaluating road surface conditions.Advanced technologies can be employed for the collection and analysis of such data,including various intrusive sensing techniques,image processing techniques,and machine learning methods.This review summarizes the state-ofthe-art of these three technologies in pavement engineering in recent years and suggests possible developments for future pavement monitoring and analysis based on these approaches.展开更多
In this paper, we make use of the functional spectral analysis to infer the periodicity of paleoclimate in the Hongzuisi section since about 15 ka. Through combined analysis of organic carbon isotope and CaCO\-3 conte...In this paper, we make use of the functional spectral analysis to infer the periodicity of paleoclimate in the Hongzuisi section since about 15 ka. Through combined analysis of organic carbon isotope and CaCO\-3 content, the law of paleoclimatic evolution of the Hongzuisi section is obtained. There were climatic changes from 10 ka to about 0.1 ka over the last 15 ka. Among these cycles, the cycle of several ka is most remarkable. The result indicates that functional spectral analysis is helpful for paleoclimatic study, which can provide useful information about paleoclimatic reconstruction and future forecast.展开更多
Fatigue failure has long been an important issue for ships and offshore structures. Among the numerous methods for predicting fatigue life, the spectral method is accepted as the most reliable. Although the theory beh...Fatigue failure has long been an important issue for ships and offshore structures. Among the numerous methods for predicting fatigue life, the spectral method is accepted as the most reliable. Although the theory behind spectral analysis is straight-forward, the analysis itself is complicated and time-consuming because it is closely related to critical technical details such as the application of fatigue loading (wave pressures and the inertial forces due to cargoes), the extraction of the stress, and the calculation of stress RAO. Here, four key technical details-loading application, displacement boundary condition, the calculation of stress RAO, and the extraction of the fatigue stress-are discussed thoroughly. For each aspect, a resolution is presented based on the finite element pre-and post-processing software MSC/PATRAN or FE solver MSC/NASTRAN. The resolutions are effective and efficient, which can help engineers perform spectral fatigue analysis accurately and faster.展开更多
Fourier transform （FF） is a commonly used method in spectral analysis of ocean wave and offshore structure responses, but it is not suitable for records of short length. In this paper another method, wavelet transfo...Fourier transform （FF） is a commonly used method in spectral analysis of ocean wave and offshore structure responses, but it is not suitable for records of short length. In this paper another method, wavelet transform （WT）, is applied to ＇analyze the data of short length. The Morlet wavelet is employed to calculate the spectra density functions for wave records and simulated Floating Production Storage and Offloading （FPSO） vessels＇ responses. Computed wave data include simulated wave data based on JONSWAP spectrum and the recorded data of Storm 149 from North Alwyn. Wavelet method is validated by comparing the statistical characteristics by WF method and those by fast Fourier transform （FFT） method with those of target spectra. The spectral density fnnctions＇ shapes calculated by WT are less malformed and have less error of statistical characteristics compared with those by FT especially when the record lengths decrease.展开更多
Traditional unsupervised seismic facies analysis techniques need to assume that seismic data obey mixed Gaussian distribution.However,fi eld seismic data may not meet this condition,thereby leading to wrong classifi c...Traditional unsupervised seismic facies analysis techniques need to assume that seismic data obey mixed Gaussian distribution.However,fi eld seismic data may not meet this condition,thereby leading to wrong classifi cation in the application of this technology.This paper introduces a spectral clustering technique for unsupervised seismic facies analysis.This algorithm is based on on the idea of a graph to cluster the data.Its kem is that seismic data are regarded as points in space,points can be connected with the edge and construct to graphs.When the graphs are divided,the weights of the edges between the different subgraphs are as low as possible,whereas the weights of the inner edges of the subgraph should be as high as possible.That has high computational complexity and entails large memory consumption for spectral clustering algorithm.To solve the problem this paper introduces the idea of sparse representation into spectral clustering.Through the selection of a small number of local sparse representation points,the spectral clustering matrix of all sample points is approximately represented to reduce the cost of spectral clustering operation.Verifi cation of physical model and fi eld data shows that the proposed approach can obtain more accurate seismic facies classification results without considering the data meet any hypothesis.The computing efficiency of this new method is better than that of the conventional spectral clustering method,thereby meeting the application needs of fi eld seismic data.展开更多
Samples of two crop seeds (corn and sesame) grown on different contaminated soil sources were collected and prepared for neutron activation analysis. Soil contamination sources were organic waste compost applied to s...Samples of two crop seeds (corn and sesame) grown on different contaminated soil sources were collected and prepared for neutron activation analysis. Soil contamination sources were organic waste compost applied to soil amendments namely, sewage sludge(Bs) and municipal solid waste (MSW) at 4%, 6% and 8% respectively. The non destructive NAA technique was used to determine some trace elements accumulation in plant seeds. Results revealed that increasing rate of tested organic waste resulted in dramatic increase in tested heavy metals levels in seeds(i.e., Fe, Zn, Co, Cr, Sc and Hg). Sesame seeds showed higher affinity to accumulate trace elements than corn grains in most tested elements. Moreover, MSW addition enhanced the accumulation of tested metals in seeds more than Bs compost.展开更多
Objective： To explore the core acupoints and combination rules of auricular acupoint therapy for simple obesity, and to further analyze the characteristics of the prescription of auricular acupoint therapy for simple...Objective： To explore the core acupoints and combination rules of auricular acupoint therapy for simple obesity, and to further analyze the characteristics of the prescription of auricular acupoint therapy for simple obesity.Methods： Relevant clinical study literature in recent 30 years in PubMed, China Biology Medicine disc（CBM）, China National Knowledge Infrastructure（CNKI）, Wan Fang Database. VIP Database and TCM Online Database was retrieved, and eligible articles were selected in order to build a prescription database of auricular acupoint therapy for simple obesity. On the basis of complex network techniques, the core acupoints and combination rules of auricular acupoint therapy for simple obesity were analyzed, and the characteristics of auricular acupoint therapy for simple obesity were analyzed comprehensively.Results： There were 46 network nodes of auricular acupoint. The top 16 core acupoints for auricular acupoint therapy for simple obesity included Nèifēnmì（内分泌CO18）, Pí（脾CO13）, Wèi（胃CO4）, Sānjiāo（三焦CO17）, Jīdiǎn（饥点）.Shénmén（神门TF4）. Dàcháng（大肠CO7）. Pízhìxià（皮质下AT4）. Fèi（肺CO14）. Shèn（肾CO10）. Jiāogǎn（交感AH6 a）, Kǒu（口CO1）,Gān（肝CO12）. Xiǎocháng（小肠CO6） and Nǎo（脑）. The combination of auricular acupoints was mainly based on the main indications of acupoints. The analysis of auricular acupoints combination indicated that the combination of CO4 with CO18 was applied most frequently, which was followed by the combinations of CO13 with CO18 and CO13 with C04. According to the analysis of auricular acupoint stimulation methods, ear point taping and pressing with Wángbùliúxíng（王不留行,Semen Vaccariae） seeds was used frequently, which was followed by magnetic beads taping and pressing and pyonex therapy. Auricular acupoint therapy combined with acupuncture for simple obesity was used most commonly, which was followed by auricular acupoint therapy combined with catgut embedment in acupoint and simple auricular acupoint therapy.Conclusion： In this study, the core acupoints and combinations of auricular acupoint therapy for simple obesity were explored effectively, and the pressing materials and major combined intervention methods were summarized and analyzed, thus providing references and treatment thoughts in terms of the point and prescription selection of auricular acupoint therapy for simple obesity.展开更多
AIM: To determine the value of bowel sounds analysis using an electronic stethoscope to support a clinical diagnosis of intestinal obstruction. METHODS: Subjects were patients who presented with a diagnosis of possibl...AIM: To determine the value of bowel sounds analysis using an electronic stethoscope to support a clinical diagnosis of intestinal obstruction. METHODS: Subjects were patients who presented with a diagnosis of possible intestinal obstruction based on symptoms, signs, and radiological findings. A 3MTH Littmann Model 4100 electronic stethoscope was used in this study. With the patients lying supine, six 8-second recordings of bowel sounds were taken from each patient from the lower abdomen. The recordings were analysed for sound duration, soundto-sound interval, dominant frequency, and peak frequency. Clinical and radiological data were reviewed and the patients were classified as having either acute, subacute, or no bowel obstruction. Comparison of bowel sound characteristics was made between these subgroups of patients. In the presence of an obstruction, the site of obstruction was identified and bowel calibre was also measured to correlate with bowel sounds. RESULTS: A total of 71 patients were studied during the period July 2009 to January 2011. Forty patientshad acute bowel obstruction (27 small bowel obstruction and 13 large bowel obstruction), 11 had subacute bowel obstruction (eight in the small bowel and three in large bowel) and 20 had no bowel obstruction (diagnoses of other conditions were made). Twenty-five patients received surgical intervention (35.2%) during the same admission for acute abdominal conditions. A total of 426 recordings were made and 420 recordings were used for analysis. There was no significant difference in sound-to-sound interval, dominant frequency, and peak frequency among patients with acute bowel obstruction, subacute bowel obstruction, and no bowel obstruction. In acute large bowel obstruction, the sound duration was significantly longer (median 0.81 s vs 0.55 s, P = 0.021) and the dominant frequency was significantly higher (median 440 Hz vs 288 Hz, P = 0.003) when compared to acute small bowel obstruction. No significant difference was seen between acute large bowel obstruction and large bowel pseudoobstruction. For patients with small bowel obstruction, the sound-to-sound interval was significantly longer in those who subsequently underwent surgery compared with those treated non-operatively (median 1.29 s vs 0.63 s, P < 0.001). There was no correlation between bowel calibre and bowel sound characteristics in both acute small bowel obstruction and acute large bowel obstruction. CONCLUSION: Auscultation of bowel sounds is nonspecific for diagnosing bowel obstruction. Differences in sound characteristics between large bowel and small bowel obstruction may help determine the likely site of obstruction.展开更多
Pneumonia is a highly transmissible disease in children.According to the World Health Organization(WHO),the most affected regions include south Asia and sub-Saharan Africa.Worldwide,15%of pediatric deaths can be attri...Pneumonia is a highly transmissible disease in children.According to the World Health Organization(WHO),the most affected regions include south Asia and sub-Saharan Africa.Worldwide,15%of pediatric deaths can be attributed to pneumonia.Computing techniques have a significant role in science,engineering,and many other fields.In this study,we focused on the efficiency of numerical techniques via computer programs.We studied the dynamics of the pneumonia-like infections of epidemic models using numerical techniques.We discuss two types of analysis:dynamical and numerical.The dynamical analysis included positivity,boundedness,local stability,reproduction number,and equilibria of the model.We also discusswell-known computing techniques including Euler,Runge Kutta,and non-standard finite difference(NSFD)for the model.The non-standard finite difference(NSFD)technique shows convergence to the true equilibrium points of the model for any time step size.However,Euler and Runge Kutta do not work well over large time intervals.Computing techniques are the suitable tool for crosschecking the theoretical analysis of the model.展开更多
Geophysical surveying is crucial in the investigation of mineral resources in poorly exposed areas such as SE-Cameroon, a region known for its gold mineral potential. In this paper, gravity survey is carried out in th...Geophysical surveying is crucial in the investigation of mineral resources in poorly exposed areas such as SE-Cameroon, a region known for its gold mineral potential. In this paper, gravity survey is carried out in the Batouri area, SE-Cameroon based on land gravity data from the Centre-south Cameroon. <span style="font-family:Verdana;">Therefore, an analytical polynomial separation program, based on least-square fi</span><span style="font-family:Verdana;">tting of a third-degree polynomial surface to the Bouguer anomaly map, was used to separate the regional/residual components in gravity data. This technique permitted to better understand the disposition of the deep and near surface structures responsible of the observed anomalies in the Batouri area. Spectral analysis and 2.5D modelling of two profiles P</span><sub><span style="font-family:Verdana;">1</span></sub><span style="font-family:Verdana;"> (SW-NE) and P</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> (N-S) selected from the residual anomaly map provided depths to basement. These depths constrain the gravity models along the profiles, indicating a variable thickness of the sedimentary infill with an approximate anomaly of -</span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">33 mGal. The 2.5D model of the basement shows a gravity body, with a signature suggesting two close and similar masses, which characterize the quartz-bearing formations associated here to granite and gneiss. Our work highlights a main heavy gravity: Gwé-Batouri anomaly, containing the major part of auriferous deposits located along the NE-SW direction. Further, three tectonic sub-basins bounded by normal faults have been highlighted at Guedal, Gwé, and Bélimban, in the south of Guedal-Bélimban depression. They are associated with the extension tectonics, more or less vertical tangential cuts and accidents that have affected the region. A correlation with previous results from tectonic, lithological and gold mineralization activities proves the relevance of the study and the need to intensify geophysical surveying in the area.</span></span></span>展开更多
The application of ti me-series modeling and forecasting method to the spectral analysis for lubricat ing oil of mechanical equipment is discussed. The AR model is used to perform a time-series modeling and forecasti...The application of ti me-series modeling and forecasting method to the spectral analysis for lubricat ing oil of mechanical equipment is discussed. The AR model is used to perform a time-series modeling and forecasting analysis for the spectral analysis data co llected from aero-engines. In the oil condition monitoring field of mechanical equipment, the use of the method of time-series analysis has rarely been report ed. As indicated in the satisfactory example, a practical method for condition m onitoring and fault forecasting of mechanical equipment has been achieved.展开更多
This study endeavors to deal with the least square spectral analysis on the time series, to find present significant frequencies, to analyze 40 tide components using harmonic methods and to show relationship between d...This study endeavors to deal with the least square spectral analysis on the time series, to find present significant frequencies, to analyze 40 tide components using harmonic methods and to show relationship between discovered frequencies and 40 components of tide. For the purpose of collecting data of altimetry satellites of Topex/Poseidon (T/P), Jason 1, Jason 2 and coastal tide gauges of Bandar Anzali, Noshahr, and Nekah were utilized. In this time series formed by cross over points of altimetry satellite and then using least square spectral analysis on time series derived from altimetry satellite and coastal tide gauges the significant components were found and annual, biannual, and monthly components were discovered. Then, analysis of 40 tide components was conducted using harmonic method to find the amplitude and phase. It represented that solar annual (Sa) plays the most significant role on Caspian Sea corresponded to the least square spectral analysis of the time series. The results shows that the annual (Sa) and semi-annual Solar (Ssa) constituents on all of the ports listed have the highest amplitude in comparison with the other constituents which are respectively 16 cm, 18 cm and 15 cm for annual constituent and 2.8 cm, 5.4 cm and 3.7 cm for semi-annual constituent.展开更多
基金supported by the National Natural Science Foundation of China(No.41804141)。
文摘Energy resolution calibration is crucial for gamma-ray spectral analysis,as measured using a scintillation detector.A locally constrained regularization method was proposed to determine the resolution calibration parameters.First,a Monte Carlo simulation model consistent with an actual measurement system was constructed to obtain the energy deposition distribution in the scintillation crystal.Subsequently,the regularization objective function is established based on weighted least squares and additional constraints.Additional constraints were designed using a special weighting scheme based on the incident gamma-ray energies.Subsequently,an intelligent algorithm was introduced to search for the optimal resolution calibration parameters by minimizing the objective function.The most appropriate regularization parameter was determined through mathematical experiments.When the regularization parameter was 30,the calibrated results exhibited the minimum RMSE.Simulations and test pit experiments were conducted to verify the performance of the proposed method.The simulation results demonstrate that the proposed algorithm can determine resolution calibration parameters more accurately than the traditional weighted least squares,and the test pit experimental results show that the R-squares between the calibrated and measured spectra are larger than 0.99.The accurate resolution calibration parameters determined by the proposed method lay the foundation for gamma-ray spectral processing and simulation benchmarking.
基金supported by the National Science Foundation of China(Grant Nos.42374205 and 41974179)the Specialized Research Fund of the National Space Science Center,Chinese Academy of Sciences(Grant No.E4PD3010)supported by the Specialized Research Fund for State Key Laboratories.
文摘The three-dimensional spectral analysis method was applied to airglow data from September 2023 to August 2024 derivedfrom an OH airglow imager located at the Hejing station (42.79°N, 83.73°E) to study the propagation characteristics of gravity waves(GWs) over Northwest China. We found that obvious seasonal variations occur in the propagation of GWs. In spring, GWs mainlypropagate in the northeast direction. In summer and autumn, GWs mainly propagate in the north direction. However, GWs mainlypropagate in the south direction in winter. The direction of GW propagation in the zonal direction is controlled by the wind-filteringeffect, whereas the north–south meridional direction is mainly determined by the location of the wave source. We found that the averageenergy spectrum exhibits a 10%–20% higher intensity in summer and winter compared with spring and autumn. For the first time, wereport the seasonal variation characteristics of GWs over the inland areas of Northwest China, which is of great significance forunderstanding the regional distribution characteristics of GWs.
基金Supported by the National Key R&D Program of China(No.2023YFC3108300)the Dalian High-level Talent Innovation Program(No.2022RG02)the Fundamental Research Funds for the Central Universities(No.3132023507)。
文摘As a frequently occurred marine pollution phenomenon,red tides of water body due to eutrophication cause massive mortality of marine organisms and serious ecological problems.The early warning and prediction of red tide outbreak can provide guidance to the coastal management,and is of great value to the aquaculture industry and marine environment protection.An approach for the risk assessment of red tide occurrence using spectral indices was made.The optimal spectral indices were explored from three candidates,namely two-band ratio(TBR)method,three-band spectral index(TBSI)method,and fluorescence baseline(FLB)method.The correlations between the spectral indices and the red tide occurrence were quantitatively evaluated through analysis of variance(ANOVA).The risk maps for the Beibu Gulf and the Bohai Bay in China were produced with the normalized spectral indices based on the multi-spectral observation from Sentinel-3 satellite.Results show that both TBR and TBSI values have significant correlations with the occurrences of red tide as the ANOVA results.TBSI illustrated correctly the risk of red tide occurrence in the risk maps and was the optimal spectral index offshore risk assessment of red tide.FLB method failed to recognize the high-risk regions and may not be the appropriate spectral index.The risk assessment method proposed in this study can provide early alarms on red tide occurrence and help timely the countermeasure against potential harms.
基金The Pre-Research Foundation of National Ministries andCommissions (No9140A16050109DZ01)the Scientific Research Program of the Education Department of Shanxi Province (No09JK701)
文摘In order to overcome the shortcomings that the reconstructed spectral reflectance may be negative when using the classic principal component analysis （PCA）to reduce the dimensions of the multi-spectral data, a nonnegative constrained principal component analysis method is proposed to construct a low-dimensional multi-spectral space and accomplish the conversion between the new constructed space and the multispectral space. First, the reason behind the negative data is analyzed and a nonnegative constraint is imposed on the classic PCA. Then a set of nonnegative linear independence weight vectors of principal components is obtained, by which a lowdimensional space is constructed. Finally, a nonlinear optimization technique is used to determine the projection vectors of the high-dimensional multi-spectral data in the constructed space. Experimental results show that the proposed method can keep the reconstructed spectral data in [ 0, 1 ]. The precision of the space created by the proposed method is equivalent to or even higher than that by the PCA.
基金Supported by Non-pesticide Replacing High-toxic Pesticides Project in Yunnan Province (ynzz-200733)~~
文摘[ Objective] The paper was to operate the application and promotion of non-pesticide replacing high-toxic pesticides techniques in Kunming City, and to analyze its benefit. [ Method ] Through application and promotion of frequency trembler grid lamps, sticking plate trapping technology, construction of treatment ponds for field waste vegetable leaves, standardized （accurate） cultivation techniques, cultivation techniques of disease-resistant varieties and diverse cultivation technologies, the promotion benefit of non-pesticide replacing high-toxic pesticides techniques was comprehensively investigated and evaluated. [ Result ] The appli- cation and promotion area of non-pesticide replacing high-toxic pesticides techniques in Kunming City during 2006 -2010 reached 94 667 hm2. The investigation on control efforts and quantitative analysis of cost/benefit showed that the beneficial result of application and promotion of non-pesticide replacing high-toxic pesticides techniques was higher than the direct benefit of application and promotion of traditional pesticide replacing techniques. This improvement innovated the traditional pesticide replacing method in replacement work of high-toxic pesticides, reducing the usage volume of pesticide in Kunming City. [ Conclusion] The application and promotion of non-pesticide replacing high-toxic pesticides techniques improved the economic, social and ecological benefit of replacement work of high-toxic pesticides, protected the agricultural ecological environment and promoted the sustainable development of agricultural production.
基金supported by the National Natural Science Foundation of China(No.91441110)
文摘Abstract The continuously rotating detonation engine （CRDE） is a new concept of engines for air- craft and spacecraft. Quasi-stable continuously rotating detonation （CRD） can be observed in an annular combustion chamber, but the sustaining, stabilizing and adjusting mechanisms are not yet clear. To learn more deeply into the CRDE, experimental studies have been carried out to inves- tigate hydrogen-oxygen CRDE. Pressure histories are obtained during each shot, which show that stable CRD waves are generated in the combustor, when feeding pressures are higher than 0.5 MPa for fuel and oxidizer, respectively. Each shot can keep running as long as fresh gas feeding main- tains. Close-up of the pressure history shows the repeatability of pressure peaks and indicates the detonation velocity in hydrogen-oxygen CRD, which proves the success of forming a stable CRD in the annular chamber. Spectrum of the pressure history matches the close-up analysis and confirms the CRD. It also shows multi-wave phenomenon and affirms the fact that in this case a single detonation wave is rotating in the annulus. Moreover, oscillation phenomenon is found in pressure peaks and a self-adjusting mechanism is proposed to explain the phenomenon.
基金The paper was supported by the National 863 High Technology Develpoment Plan Project(Grant No.2001AA602015)
文摘The spectral methods and ice-induced fatigue analysis are discussed based on Miner＇s linear cumulative fatigue hypothesis and S-N curve data. According to the long-term data of full-scale tests on the platforms in the Bohai Sea, the ice force spectrum of conical structures and the fatigue environmental model are established. Moreover, the finite element model of JZ20-2MSW platform, an example of ice-induced fatigue analysis, is built with ANSYS software. The mode analysis and dynamic analysis in frequency domain under all kinds of ice fatigue work conditions are carded on, and the fatigue life of the structure is estimated in detail. The methods in this paper can be helpful in ice-induced fatigue analysis of ice-resistant platforms.
基金Project supported by the National Natural Science Foundation of China.
文摘Response spectral moments are useful for system reliability analysis.Usually,spectral mo- ments are calculated by the frequency domain method.Based on the time domain modal analysis of random vibrations,the authors present a new method for calculating response spectral moments through response correlation functions.The method can be applied to both classical and non-classical damping cases and to three kinds of random excitations,i.e.,white noise,band-limited white noise, and filtered white noise.
基金supported by the National Key R&D Program of China(2017YFF0205600)the International Research Cooperation Seed Fund of Beijing University of Technology(2018A08)+1 种基金Science and Technology Project of Beijing Municipal Commission of Transport(2018-kjc-01-213)the Construction of Service Capability of Scientific and Technological Innovation-Municipal Level of Fundamental Research Funds(Scientific Research Categories)of Beijing City(PXM2019_014204_500032).
文摘In modern transportation,pavement is one of the most important civil infrastructures for the movement of vehicles and pedestrians.Pavement service quality and service life are of great importance for civil engineers as they directly affect the regular service for the users.Therefore,monitoring the health status of pavement before irreversible damage occurs is essential for timely maintenance,which in turn ensures public transportation safety.Many pavement damages can be detected and analyzed by monitoring the structure dynamic responses and evaluating road surface conditions.Advanced technologies can be employed for the collection and analysis of such data,including various intrusive sensing techniques,image processing techniques,and machine learning methods.This review summarizes the state-ofthe-art of these three technologies in pavement engineering in recent years and suggests possible developments for future pavement monitoring and analysis based on these approaches.
基金GrantedbytheNationalNaturalScienceFoundationofChina (No .4 9972 0 5 7)
文摘In this paper, we make use of the functional spectral analysis to infer the periodicity of paleoclimate in the Hongzuisi section since about 15 ka. Through combined analysis of organic carbon isotope and CaCO\-3 content, the law of paleoclimatic evolution of the Hongzuisi section is obtained. There were climatic changes from 10 ka to about 0.1 ka over the last 15 ka. Among these cycles, the cycle of several ka is most remarkable. The result indicates that functional spectral analysis is helpful for paleoclimatic study, which can provide useful information about paleoclimatic reconstruction and future forecast.
文摘Fatigue failure has long been an important issue for ships and offshore structures. Among the numerous methods for predicting fatigue life, the spectral method is accepted as the most reliable. Although the theory behind spectral analysis is straight-forward, the analysis itself is complicated and time-consuming because it is closely related to critical technical details such as the application of fatigue loading (wave pressures and the inertial forces due to cargoes), the extraction of the stress, and the calculation of stress RAO. Here, four key technical details-loading application, displacement boundary condition, the calculation of stress RAO, and the extraction of the fatigue stress-are discussed thoroughly. For each aspect, a resolution is presented based on the finite element pre-and post-processing software MSC/PATRAN or FE solver MSC/NASTRAN. The resolutions are effective and efficient, which can help engineers perform spectral fatigue analysis accurately and faster.
文摘Fourier transform （FF） is a commonly used method in spectral analysis of ocean wave and offshore structure responses, but it is not suitable for records of short length. In this paper another method, wavelet transform （WT）, is applied to ＇analyze the data of short length. The Morlet wavelet is employed to calculate the spectra density functions for wave records and simulated Floating Production Storage and Offloading （FPSO） vessels＇ responses. Computed wave data include simulated wave data based on JONSWAP spectrum and the recorded data of Storm 149 from North Alwyn. Wavelet method is validated by comparing the statistical characteristics by WF method and those by fast Fourier transform （FFT） method with those of target spectra. The spectral density fnnctions＇ shapes calculated by WT are less malformed and have less error of statistical characteristics compared with those by FT especially when the record lengths decrease.
基金This work was supported by National Natural Science Foundation of China(Nos.U1562218,41604107,and 41804126).
文摘Traditional unsupervised seismic facies analysis techniques need to assume that seismic data obey mixed Gaussian distribution.However,fi eld seismic data may not meet this condition,thereby leading to wrong classifi cation in the application of this technology.This paper introduces a spectral clustering technique for unsupervised seismic facies analysis.This algorithm is based on on the idea of a graph to cluster the data.Its kem is that seismic data are regarded as points in space,points can be connected with the edge and construct to graphs.When the graphs are divided,the weights of the edges between the different subgraphs are as low as possible,whereas the weights of the inner edges of the subgraph should be as high as possible.That has high computational complexity and entails large memory consumption for spectral clustering algorithm.To solve the problem this paper introduces the idea of sparse representation into spectral clustering.Through the selection of a small number of local sparse representation points,the spectral clustering matrix of all sample points is approximately represented to reduce the cost of spectral clustering operation.Verifi cation of physical model and fi eld data shows that the proposed approach can obtain more accurate seismic facies classification results without considering the data meet any hypothesis.The computing efficiency of this new method is better than that of the conventional spectral clustering method,thereby meeting the application needs of fi eld seismic data.
文摘Samples of two crop seeds (corn and sesame) grown on different contaminated soil sources were collected and prepared for neutron activation analysis. Soil contamination sources were organic waste compost applied to soil amendments namely, sewage sludge(Bs) and municipal solid waste (MSW) at 4%, 6% and 8% respectively. The non destructive NAA technique was used to determine some trace elements accumulation in plant seeds. Results revealed that increasing rate of tested organic waste resulted in dramatic increase in tested heavy metals levels in seeds(i.e., Fe, Zn, Co, Cr, Sc and Hg). Sesame seeds showed higher affinity to accumulate trace elements than corn grains in most tested elements. Moreover, MSW addition enhanced the accumulation of tested metals in seeds more than Bs compost.
基金Supported by special program of scientific research in Traditional Chinese Medicine in 2015(201507003)National Natural Science Foundation of China(81674081)~~
文摘Objective： To explore the core acupoints and combination rules of auricular acupoint therapy for simple obesity, and to further analyze the characteristics of the prescription of auricular acupoint therapy for simple obesity.Methods： Relevant clinical study literature in recent 30 years in PubMed, China Biology Medicine disc（CBM）, China National Knowledge Infrastructure（CNKI）, Wan Fang Database. VIP Database and TCM Online Database was retrieved, and eligible articles were selected in order to build a prescription database of auricular acupoint therapy for simple obesity. On the basis of complex network techniques, the core acupoints and combination rules of auricular acupoint therapy for simple obesity were analyzed, and the characteristics of auricular acupoint therapy for simple obesity were analyzed comprehensively.Results： There were 46 network nodes of auricular acupoint. The top 16 core acupoints for auricular acupoint therapy for simple obesity included Nèifēnmì（内分泌CO18）, Pí（脾CO13）, Wèi（胃CO4）, Sānjiāo（三焦CO17）, Jīdiǎn（饥点）.Shénmén（神门TF4）. Dàcháng（大肠CO7）. Pízhìxià（皮质下AT4）. Fèi（肺CO14）. Shèn（肾CO10）. Jiāogǎn（交感AH6 a）, Kǒu（口CO1）,Gān（肝CO12）. Xiǎocháng（小肠CO6） and Nǎo（脑）. The combination of auricular acupoints was mainly based on the main indications of acupoints. The analysis of auricular acupoints combination indicated that the combination of CO4 with CO18 was applied most frequently, which was followed by the combinations of CO13 with CO18 and CO13 with C04. According to the analysis of auricular acupoint stimulation methods, ear point taping and pressing with Wángbùliúxíng（王不留行,Semen Vaccariae） seeds was used frequently, which was followed by magnetic beads taping and pressing and pyonex therapy. Auricular acupoint therapy combined with acupuncture for simple obesity was used most commonly, which was followed by auricular acupoint therapy combined with catgut embedment in acupoint and simple auricular acupoint therapy.Conclusion： In this study, the core acupoints and combinations of auricular acupoint therapy for simple obesity were explored effectively, and the pressing materials and major combined intervention methods were summarized and analyzed, thus providing references and treatment thoughts in terms of the point and prescription selection of auricular acupoint therapy for simple obesity.
文摘AIM: To determine the value of bowel sounds analysis using an electronic stethoscope to support a clinical diagnosis of intestinal obstruction. METHODS: Subjects were patients who presented with a diagnosis of possible intestinal obstruction based on symptoms, signs, and radiological findings. A 3MTH Littmann Model 4100 electronic stethoscope was used in this study. With the patients lying supine, six 8-second recordings of bowel sounds were taken from each patient from the lower abdomen. The recordings were analysed for sound duration, soundto-sound interval, dominant frequency, and peak frequency. Clinical and radiological data were reviewed and the patients were classified as having either acute, subacute, or no bowel obstruction. Comparison of bowel sound characteristics was made between these subgroups of patients. In the presence of an obstruction, the site of obstruction was identified and bowel calibre was also measured to correlate with bowel sounds. RESULTS: A total of 71 patients were studied during the period July 2009 to January 2011. Forty patientshad acute bowel obstruction (27 small bowel obstruction and 13 large bowel obstruction), 11 had subacute bowel obstruction (eight in the small bowel and three in large bowel) and 20 had no bowel obstruction (diagnoses of other conditions were made). Twenty-five patients received surgical intervention (35.2%) during the same admission for acute abdominal conditions. A total of 426 recordings were made and 420 recordings were used for analysis. There was no significant difference in sound-to-sound interval, dominant frequency, and peak frequency among patients with acute bowel obstruction, subacute bowel obstruction, and no bowel obstruction. In acute large bowel obstruction, the sound duration was significantly longer (median 0.81 s vs 0.55 s, P = 0.021) and the dominant frequency was significantly higher (median 440 Hz vs 288 Hz, P = 0.003) when compared to acute small bowel obstruction. No significant difference was seen between acute large bowel obstruction and large bowel pseudoobstruction. For patients with small bowel obstruction, the sound-to-sound interval was significantly longer in those who subsequently underwent surgery compared with those treated non-operatively (median 1.29 s vs 0.63 s, P < 0.001). There was no correlation between bowel calibre and bowel sound characteristics in both acute small bowel obstruction and acute large bowel obstruction. CONCLUSION: Auscultation of bowel sounds is nonspecific for diagnosing bowel obstruction. Differences in sound characteristics between large bowel and small bowel obstruction may help determine the likely site of obstruction.
文摘Pneumonia is a highly transmissible disease in children.According to the World Health Organization(WHO),the most affected regions include south Asia and sub-Saharan Africa.Worldwide,15%of pediatric deaths can be attributed to pneumonia.Computing techniques have a significant role in science,engineering,and many other fields.In this study,we focused on the efficiency of numerical techniques via computer programs.We studied the dynamics of the pneumonia-like infections of epidemic models using numerical techniques.We discuss two types of analysis:dynamical and numerical.The dynamical analysis included positivity,boundedness,local stability,reproduction number,and equilibria of the model.We also discusswell-known computing techniques including Euler,Runge Kutta,and non-standard finite difference(NSFD)for the model.The non-standard finite difference(NSFD)technique shows convergence to the true equilibrium points of the model for any time step size.However,Euler and Runge Kutta do not work well over large time intervals.Computing techniques are the suitable tool for crosschecking the theoretical analysis of the model.
文摘Geophysical surveying is crucial in the investigation of mineral resources in poorly exposed areas such as SE-Cameroon, a region known for its gold mineral potential. In this paper, gravity survey is carried out in the Batouri area, SE-Cameroon based on land gravity data from the Centre-south Cameroon. <span style="font-family:Verdana;">Therefore, an analytical polynomial separation program, based on least-square fi</span><span style="font-family:Verdana;">tting of a third-degree polynomial surface to the Bouguer anomaly map, was used to separate the regional/residual components in gravity data. This technique permitted to better understand the disposition of the deep and near surface structures responsible of the observed anomalies in the Batouri area. Spectral analysis and 2.5D modelling of two profiles P</span><sub><span style="font-family:Verdana;">1</span></sub><span style="font-family:Verdana;"> (SW-NE) and P</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> (N-S) selected from the residual anomaly map provided depths to basement. These depths constrain the gravity models along the profiles, indicating a variable thickness of the sedimentary infill with an approximate anomaly of -</span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">33 mGal. The 2.5D model of the basement shows a gravity body, with a signature suggesting two close and similar masses, which characterize the quartz-bearing formations associated here to granite and gneiss. Our work highlights a main heavy gravity: Gwé-Batouri anomaly, containing the major part of auriferous deposits located along the NE-SW direction. Further, three tectonic sub-basins bounded by normal faults have been highlighted at Guedal, Gwé, and Bélimban, in the south of Guedal-Bélimban depression. They are associated with the extension tectonics, more or less vertical tangential cuts and accidents that have affected the region. A correlation with previous results from tectonic, lithological and gold mineralization activities proves the relevance of the study and the need to intensify geophysical surveying in the area.</span></span></span>
文摘The application of ti me-series modeling and forecasting method to the spectral analysis for lubricat ing oil of mechanical equipment is discussed. The AR model is used to perform a time-series modeling and forecasting analysis for the spectral analysis data co llected from aero-engines. In the oil condition monitoring field of mechanical equipment, the use of the method of time-series analysis has rarely been report ed. As indicated in the satisfactory example, a practical method for condition m onitoring and fault forecasting of mechanical equipment has been achieved.
文摘This study endeavors to deal with the least square spectral analysis on the time series, to find present significant frequencies, to analyze 40 tide components using harmonic methods and to show relationship between discovered frequencies and 40 components of tide. For the purpose of collecting data of altimetry satellites of Topex/Poseidon (T/P), Jason 1, Jason 2 and coastal tide gauges of Bandar Anzali, Noshahr, and Nekah were utilized. In this time series formed by cross over points of altimetry satellite and then using least square spectral analysis on time series derived from altimetry satellite and coastal tide gauges the significant components were found and annual, biannual, and monthly components were discovered. Then, analysis of 40 tide components was conducted using harmonic method to find the amplitude and phase. It represented that solar annual (Sa) plays the most significant role on Caspian Sea corresponded to the least square spectral analysis of the time series. The results shows that the annual (Sa) and semi-annual Solar (Ssa) constituents on all of the ports listed have the highest amplitude in comparison with the other constituents which are respectively 16 cm, 18 cm and 15 cm for annual constituent and 2.8 cm, 5.4 cm and 3.7 cm for semi-annual constituent.
