Automatic modulation recognition(AMR)of radiation source signals is a research focus in the field of cognitive radio.However,the AMR of radiation source signals at low SNRs still faces a great challenge.Therefore,the ...Automatic modulation recognition(AMR)of radiation source signals is a research focus in the field of cognitive radio.However,the AMR of radiation source signals at low SNRs still faces a great challenge.Therefore,the AMR method of radiation source signals based on two-dimensional data matrix and improved residual neural network is proposed in this paper.First,the time series of the radiation source signals are reconstructed into two-dimensional data matrix,which greatly simplifies the signal preprocessing process.Second,the depthwise convolution and large-size convolutional kernels based residual neural network(DLRNet)is proposed to improve the feature extraction capability of the AMR model.Finally,the model performs feature extraction and classification on the two-dimensional data matrix to obtain the recognition vector that represents the signal modulation type.Theoretical analysis and simulation results show that the AMR method based on two-dimensional data matrix and improved residual network can significantly improve the accuracy of the AMR method.The recognition accuracy of the proposed method maintains a high level greater than 90% even at -14 dB SNR.展开更多
Electromagnetic Radiation Source Identification(ERSI) is a key technology that is widely used in military and radiation management and in electromagnetic interference diagnostics.The discriminative capability of machi...Electromagnetic Radiation Source Identification(ERSI) is a key technology that is widely used in military and radiation management and in electromagnetic interference diagnostics.The discriminative capability of machine learning methods has recently been used for facilitating ERSI.This paper presents a new approach to improve ERSI by adopting support vector machines,which are proven to be effective tools in pattern classification and regression,on the basis of the spatial distribution of electromagnetic radiation sources.Spatial information is converted from 3D cubes to 1D vectors with subscripts as inputs in order to simplify the model.The model is trained with 187 500 data sets in order to enable it to identify the types of radiation source types with an accuracy of up to 99.9%.The influence of parameters(e.g.,penalty parameter,reflection and noise from the ambient environment,and the scaling method for the input data) are discussed.The proposed method has good performance in noisy and reverberant environment.It has an identification accuracy of 82.15% when the signal-to-noise ratio is 20 dB.The proposed method has better accuracy in a noisy environment than artificial neural networks.Given that each Electromagnetic(EM) source has unique spatial characteristics,this method can be used for EM source identification and EM interference diagnostics.展开更多
An X-ray radiation source with approximately constant radiation temperature is realized by irradiating golden hohlraum with a shaped laser pulse. A simple theoretical model based on power balance is used to design the...An X-ray radiation source with approximately constant radiation temperature is realized by irradiating golden hohlraum with a shaped laser pulse. A simple theoretical model based on power balance is used to design the shape of the drive laser pulse. Experiments are carried out on the Shenguang III prototype laser facility, and the experimentM results are presented for radiation sources with the flat-top lasting about 2.5 ns at two different peak temperatures of about 150 eV and 170 eV, respectively, including the the drive laser pulses and the time integrated possible improvements are discussed. time histories of the temperatures, the shapes of radiation spectra. The validity of the model and展开更多
In order to acquire a broadband absorption spectrum in a single shot,a compact radiation source was developed by using a Z-pinch type electric discharge.This paper presents the mechanical and electrical construction o...In order to acquire a broadband absorption spectrum in a single shot,a compact radiation source was developed by using a Z-pinch type electric discharge.This paper presents the mechanical and electrical construction of the source,as well as its electrical and optical characteristics,including the intense continuum of radiation emitted by the source in the UV and visible spectral range.It also shows that the compactness of the source allows direct coupling with the probed medium,enabling broadband absorption measurement in the spectral range of 200e300 nm without use of an optical fiber which strongly attenuates the light in the short wavelength range.Concretely,thanks to this source,broadband spectral absorption of NO molecules around 210 nm and that of OH molecules around 310 nm were recorded in this direct coupling arrangement.Copper atom spectral absorption around 325 nm of the peripheral cold zones of an intense transient arc was also recorded.展开更多
Radiation source identification plays an important role in non-cooperative communication scene and numerous methods have been proposed in this field. Deep learning has gained popularity in a variety of computer vision...Radiation source identification plays an important role in non-cooperative communication scene and numerous methods have been proposed in this field. Deep learning has gained popularity in a variety of computer vision tasks. Recently, it has also been successfully applied for radiation source identification.However, training deep neural networks for classification requires a large number of labeled samples, and in non-cooperative applications, it is unrealistic. This paper proposes a method for the unlabeled samples of unknown radiation source. It uses semi-supervised learning to detect unlabeled samples and label new samples automatically. It avoids retraining the neural network with parameter-transfer learning. The results show that compared with the traditional algorithms, the proposed algorithm can offer better accuracy.展开更多
An experiment was performed on the Shenguang III prototype laser facility to continue the study on hohlraum radiation source with approximately constant radiation temperature using a continuously shaped laser pulse.A ...An experiment was performed on the Shenguang III prototype laser facility to continue the study on hohlraum radiation source with approximately constant radiation temperature using a continuously shaped laser pulse.A radiation source with a flattop temperature of about130 e V that lasted about 5 ns was obtained.The previous analytical iteration method based on power balance and self-similar solution of ablation was modified taking into account the plasma movements and it was used to design the laser pulse shape for experiment.A comparison between experimental results and simulation is presented and better agreement was achieved using the modified method.Further improvements are discussed.展开更多
The undulator is the key component in the compact THz radiation source based on FEL.By matching the adjustable period magnetic field of the undulator with the optical resonance cavity,the passing electron beam will ge...The undulator is the key component in the compact THz radiation source based on FEL.By matching the adjustable period magnetic field of the undulator with the optical resonance cavity,the passing electron beam will generate coherent radiation with gain,and the radiation power required by THz source can be achieved finally. Compared with the pure permanent magnet type,the hybrid type undulator can decrease the field errors caused by non-homogeneous magnetization of magnetic blocks,and provide higher magnetic field.The conceptual design of a hybrid undulator used for THz radiation source is introduced.We use the FEM code OPERA/TOSCA to simulate 3D magnetic field of the undulator.After optimizing the end structure of the hybrid undulator,the first field integrals is controlled within 0.01Gs.m,and the deviation of the electron beam is less than 0.02mm.展开更多
The spatial orientation of optical radiation sources has long been the hot topic in the aerospace and the military applications.Current researches mainly focus on the high precision orientation on the partial field of...The spatial orientation of optical radiation sources has long been the hot topic in the aerospace and the military applications.Current researches mainly focus on the high precision orientation on the partial field of view.Thus,combination of several partial fields of view is required to achieve orientation when the field of view exceeds 180°,which results in the increase of size,weight,power consumption and the cost.By defining radiation energy and direction of the optical radiation source as a vector and applying the cosine law of radiation and vector theorem,it is shown that the vector can be obtained from unit normal vectors on the three un-coplanar surfaces and from the energy projected by the optical radiation source.Based on this,an orientation method with 360° full field of view by a polyhedron is suggested,the mathematical formula for anti-multipath interference is supposed and the error upper limit is derived.The feasibility and effectiveness of this method are validated by measurements and simulation.An accuracy better than 2.866° and 0.574° is achieved when the ratio of measurement error of energy on arbitrary surface and the true value are 5% and 1%,respectively,given the matrix composed of unit normal vectors on three measurement surfaces is orthogonal.展开更多
An equivalent radiation source method is proposed to characterize electromagnetic emission and interference of complex three dimensional integrated circuits（IC） in this paper.The method utilizes amplitude-only near-...An equivalent radiation source method is proposed to characterize electromagnetic emission and interference of complex three dimensional integrated circuits（IC） in this paper.The method utilizes amplitude-only near-field scanning data to reconstruct an equivalent magnetic dipole array,and the differential evolution optimization algorithm is proposed to extract the locations,orientation and moments of those dipoles.By importing the equivalent dipoles model into a 3D full-wave simulator together with the victim circuit model,the electromagnetic interference issues in mixed RF/digital systems can be well predicted.A commercial IC is used to validate the accuracy and efficiency of this proposed method.The coupled power at the victim antenna port calculated by the equivalent radiation source is compared with the measured data.Good consistency is obtained which confirms the validity and efficiency of the method.展开更多
For maritime radiation source target tracking in particular electronic counter measures（ECM）environment,there exists two main problems which can deteriorate the tracking performance of traditional approaches.The frs...For maritime radiation source target tracking in particular electronic counter measures（ECM）environment,there exists two main problems which can deteriorate the tracking performance of traditional approaches.The frst problem is the poor observability of the radiation source.The second one is the measurement uncertainty which includes the uncertainty of the target appearing/disappearing and the detection uncertainty（false and missed detections）.A novel approach is proposed in this paper for tracking maritime radiation source in the presence of measurement uncertainty.To solve the poor observability of maritime radiation source target,using the radiation source motion restriction,the observer altitude information is incorporated into the bearings-only tracking（BOT）method to obtain the unique target localization.Then the two uncertainties in the ECM environment are modeled by the random fnite set（RFS）theory and the Bernoulli fltering method with the observer altitude is adopted to solve the tracking problem of maritime radiation source in such context.Simulation experiments verify the validity of the proposed approach for tracking maritime radiation source,and also demonstrate the superiority of the method compared with the traditional integrated probabilistic data association（IPDA）method.The tracking performance under different conditions,particularly those involving different duration of radiation source opening and switching-off,indicates that the method to solve our problem is robust and effective.展开更多
In recent years,in order to meet the practical needs of deep edge mine detection with large depth and high precision,transient electromagnetic method(TEM)near emission source detection mode has become an international...In recent years,in order to meet the practical needs of deep edge mine detection with large depth and high precision,transient electromagnetic method(TEM)near emission source detection mode has become an international advanced method(Xue et al.,2020).展开更多
The PeTa (Perelman-Tatartchenko) effect is the radiation of the energy of a first-order phase transition during the transition from a less condensed phase to a more condensed one. The effect was independently discover...The PeTa (Perelman-Tatartchenko) effect is the radiation of the energy of a first-order phase transition during the transition from a less condensed phase to a more condensed one. The effect was independently discovered by M. Perelman and the author of this paper. Six papers on the PeTa effect have been published in this journal over the past nine years. They are devoted to the development of PeTa models to explain the following phenomena: IR radiation from cold surfaces, cavitation luminescence/sonoluminescence (CL/SL), laser-induced bubble luminescence (LIBL), and vapor bubble luminescence (VBL) in underwater geysers. This paper describes the sources of PeTa radiation in the Earth’s atmosphere. These sources of infrared radiation have been investigated by numerous research groups, but their interpretation either does not exist at all, or it is erroneous. The following phenomena are specifically considered: PeTa radiation during the formation of clouds and fog;a pulse laser based on the PeTa radiation;condensation explosions as sources of PaTa radiation;measurement of the concentration of water vapor in the atmosphere using PeTa radiation;atmospheric scintillation of infrared radiation in the atmosphere due to the PeTa effect;PeTa radiation as a source of comfort for the igloo;the influence of PeTa radiation on living organisms;PeTa radiation due to characteristics of tropical storms;PeTa radiation as a possible precursor to earthquakes. The problem of global warming, which worries everyone, as it turns out, is also associated with the PeTa effect.展开更多
MCNPX(Monte Carlo N-Particle Transport Code)computer code is used to design a model to CANDU(Canada Deuterium Uranium)reactor core and its shielding system.It is assumed that reactor core is fueled with natural uraniu...MCNPX(Monte Carlo N-Particle Transport Code)computer code is used to design a model to CANDU(Canada Deuterium Uranium)reactor core and its shielding system.It is assumed that reactor core is fueled with natural uranium.The core radiation sources are calculated which consider prompt neutrons,neutron induced gamma and prompt gamma radiations.The total neutron flux and dose rate are calculated along the shield and at outer shield points.The results indicated that the major dose rate component at outer shield points is due to neutron induced gamma dose rate(μSv/h).展开更多
Swelling property of acrylamide hydrogels,prepared from aqueous solutions of acrylamide monomer havingconcentrations in the range of 10-60 wt% by ray irradiation method using a Co-60 gamma radiation source at dosesran...Swelling property of acrylamide hydrogels,prepared from aqueous solutions of acrylamide monomer havingconcentrations in the range of 10-60 wt% by ray irradiation method using a Co-60 gamma radiation source at dosesranging 1-30.0 kGy,has been investigated under various swelling media.These swelling media were basically solvents(solutions),produced by dissolving methanol,ethanol,glucose,sucrose,sodium chloride and sodium persulfate individuallywith distilled water,and solutions prepared with pHs=3,7 and 10.The investigation was performed in order to observe theeffect of these solvents and pHs as well as the influence of monomer concentrations,radiation doses and times on swellingbehavior of hydrogels.Swelling values were found higher for hydrogels prepared with lower monomer concentrations(ca.20 wt%)and radiation doses(ca.5 kGy)and showed a leveling off tendency within 24 h.The glucose solvent and the buffersolution of pH=10 revealed significant increase of swelling of hydrogels as compared to other solutions.Results areexplained based on crosslinking density in hydrogel,polymer-solvent/polymer-polymer interactions in solutions,permeability of molecules in solutions and ionization capacity of hydrogel in pH.展开更多
A penetrating view of the three-dimensional nanostructure of female spermatheca and male flagellum in the species Aleochara verna is obtained with 100-nm resolution using a hard X-ray microscope, which provides a fast...A penetrating view of the three-dimensional nanostructure of female spermatheca and male flagellum in the species Aleochara verna is obtained with 100-nm resolution using a hard X-ray microscope, which provides a fast noninvasive imaging technology for insect morphology. Through introducing Zernike phase contrast and heavy metal staining, images taken at 8 keV displayed sufficient contrast for observing nanoscale fine structures, such as the spermatheca cochleate duct and the subapex of the flagellum, which have some implications for the study of the sperm transfer process and genital evolution in insects. This work shows that both the spatial resolution and the contrast characteristic of hard X-ray microscopy are quite promising for insect morphology studies and, particularly, provide an attractive alternative to the destructive techniques used for investigating internal soft tissues.展开更多
Radiation simulation utilizing plasma radiation sources (PRS) generates a large number of undesirable debris, which may damage the expensive diagnosing detectors. An ultra fast shutter (UFS) driven by pulsed high curr...Radiation simulation utilizing plasma radiation sources (PRS) generates a large number of undesirable debris, which may damage the expensive diagnosing detectors. An ultra fast shutter (UFS) driven by pulsed high current can erect a physical barrier to the slowly moving debris after allowing the passage of X-ray photons. The UFS consists of a pair of thin metal foils twisting the parallel axes in a Nylon cassette, compressed with an outer magnetic field, generated from a fast capacitor bank, discharging into a single turn loop. A typical capacitor bank is of 7.5μF charging voltages varying from 30 kV to 45 kV, with corresponding currents of approximately 90 kA to140 kA and discharging current periods of approximately 13.1μs. A shutter closing time as fast as 38 microseconds has been obtained with an aluminium foil thickness of 100 micrometers and a cross-sectional area of 15 mm by 20 mm. The design, construction and the expressions of the valve-closing time of the UFS are presented along with the measured results of valve-closing velocities.展开更多
Vacuum ultraviolet(VUV)photoionization and photodissociation of methylcyclohexane have been studied utilizing a reflectron time-of-flight mass spectrometer(RTOF-MS)with synchrotron radiation source.Photoionization eff...Vacuum ultraviolet(VUV)photoionization and photodissociation of methylcyclohexane have been studied utilizing a reflectron time-of-flight mass spectrometer(RTOF-MS)with synchrotron radiation source.Photoionization efficiency curves(PIEs)of molecule ion C7H14^+ and fragment ions C7H13^+,C6H11^+,C6H10+,C5H10^+,C5H9^+,C4H8^+,C4H7^+,and C3H5^+ were observed.The ionization energy of methylcyclohexane was measured to be(9.80±0.03)eV,and appearance energies of fragment ions were determined from the PIEs.Optimized structures of transitional states,intermediates and product ions were characterized at the B3LYP/6-31G(d)level and the energies were calculated using G3B3 method.Formation channels of dominating fragment ions were proposed.Intramolecular hydrogen migrations and carbon ring-opening were the foremost processes in fragmentation pathways of methylcyclohexane.展开更多
A theoretical model is presented to describe the parametric acoustic field generated by a piston radiator. In the model, the high-frequency primary wave interaction region that is truncated by a low-pass acoustic filt...A theoretical model is presented to describe the parametric acoustic field generated by a piston radiator. In the model, the high-frequency primary wave interaction region that is truncated by a low-pass acoustic filter can be viewed as a cylindrical source within the Rayleigh distance of the piston. When the radius of the piston is much smaller than the length of the parametric region, this model is reduced to the Berketey's End-Fire Line Army model. Comparison between numerical calculations and experimental measurement show that the generated parametric sound field (especially near the axis) agrees well with the experiment results.展开更多
The Volume Source Boundary Point Method (VSBPM) is greatly improved so that it will speed up the VSBPM's solution of the acoustic radiation problem caused by the vibrating body. The fundamental solution provided b...The Volume Source Boundary Point Method (VSBPM) is greatly improved so that it will speed up the VSBPM's solution of the acoustic radiation problem caused by the vibrating body. The fundamental solution provided by Helmholtz equation is enforced in a weighted residual sense over a tetrahedron located on the normal line of the boundary node to replace the coefficient matrices of the system equation. Through the enhanced volume source boundary point analysis of various examples and the sound field of a vibrating rectangular box in a semi-anechoic chamber, it has revealed that the calculating speed of the EVSBPM is more than 10 times faster than that of the VSBPM while it works on the aspects of its calculating precision and stability, adaptation to geometric shape of vibrating body as well as its ability to overcome the non-uniqueness problem.展开更多
The Qianguo Ms5. 8 earthquake swarm of 2013 occurred in Qianguo, Jilin Province, China. There are five earthquakes with Ms ≥5. 0 in the Qianguo earthquake swarm, with magnitudes of Ms 5. 5, Ms 5. 0, Ms 5. 3, Ms 5. 8 ...The Qianguo Ms5. 8 earthquake swarm of 2013 occurred in Qianguo, Jilin Province, China. There are five earthquakes with Ms ≥5. 0 in the Qianguo earthquake swarm, with magnitudes of Ms 5. 5, Ms 5. 0, Ms 5. 3, Ms 5. 8 and Ms 5. 0. In this study, the far-field seismic radiated energy characteristics of the earthquakes are compared based on the source spectrum and the ground motion spectrum of the earthquake swarm. The ground motion spectrum of the five earthquakes at Changchun seismic station （CN2）, which is the national standard station, is first investigated with the recorded ground motions, and then the far-field seismic radiated energy is calculated and combined with the relationships of the source spectrum to describe the variable characteristics of the Qianguo earthquake swarm. Research results indicate that the second earthquake （No. 2） with Ms5. 0 is the key event of the earthquake swarm, which occurred on October 31, the same day following the first Ms5. 5 earthquake （No.l）. In fact, the magnitude of event No. 2 decreased compared to event No.l, which did not agree with its large far-field seismic radiated energy. It needs to be pointed out that event No. 2 was the turning point event of the Qianguo earthquake swarm, as being a significant transition before the largest Ms5. 8 earthquake.展开更多
基金National Natural Science Foundation of China under Grant No.61973037China Postdoctoral Science Foundation under Grant No.2022M720419。
文摘Automatic modulation recognition(AMR)of radiation source signals is a research focus in the field of cognitive radio.However,the AMR of radiation source signals at low SNRs still faces a great challenge.Therefore,the AMR method of radiation source signals based on two-dimensional data matrix and improved residual neural network is proposed in this paper.First,the time series of the radiation source signals are reconstructed into two-dimensional data matrix,which greatly simplifies the signal preprocessing process.Second,the depthwise convolution and large-size convolutional kernels based residual neural network(DLRNet)is proposed to improve the feature extraction capability of the AMR model.Finally,the model performs feature extraction and classification on the two-dimensional data matrix to obtain the recognition vector that represents the signal modulation type.Theoretical analysis and simulation results show that the AMR method based on two-dimensional data matrix and improved residual network can significantly improve the accuracy of the AMR method.The recognition accuracy of the proposed method maintains a high level greater than 90% even at -14 dB SNR.
基金supported by the National Natural Science Foundation of China under Grant No.61201024
文摘Electromagnetic Radiation Source Identification(ERSI) is a key technology that is widely used in military and radiation management and in electromagnetic interference diagnostics.The discriminative capability of machine learning methods has recently been used for facilitating ERSI.This paper presents a new approach to improve ERSI by adopting support vector machines,which are proven to be effective tools in pattern classification and regression,on the basis of the spatial distribution of electromagnetic radiation sources.Spatial information is converted from 3D cubes to 1D vectors with subscripts as inputs in order to simplify the model.The model is trained with 187 500 data sets in order to enable it to identify the types of radiation source types with an accuracy of up to 99.9%.The influence of parameters(e.g.,penalty parameter,reflection and noise from the ambient environment,and the scaling method for the input data) are discussed.The proposed method has good performance in noisy and reverberant environment.It has an identification accuracy of 82.15% when the signal-to-noise ratio is 20 dB.The proposed method has better accuracy in a noisy environment than artificial neural networks.Given that each Electromagnetic(EM) source has unique spatial characteristics,this method can be used for EM source identification and EM interference diagnostics.
文摘An X-ray radiation source with approximately constant radiation temperature is realized by irradiating golden hohlraum with a shaped laser pulse. A simple theoretical model based on power balance is used to design the shape of the drive laser pulse. Experiments are carried out on the Shenguang III prototype laser facility, and the experimentM results are presented for radiation sources with the flat-top lasting about 2.5 ns at two different peak temperatures of about 150 eV and 170 eV, respectively, including the the drive laser pulses and the time integrated possible improvements are discussed. time histories of the temperatures, the shapes of radiation spectra. The validity of the model and
文摘In order to acquire a broadband absorption spectrum in a single shot,a compact radiation source was developed by using a Z-pinch type electric discharge.This paper presents the mechanical and electrical construction of the source,as well as its electrical and optical characteristics,including the intense continuum of radiation emitted by the source in the UV and visible spectral range.It also shows that the compactness of the source allows direct coupling with the probed medium,enabling broadband absorption measurement in the spectral range of 200e300 nm without use of an optical fiber which strongly attenuates the light in the short wavelength range.Concretely,thanks to this source,broadband spectral absorption of NO molecules around 210 nm and that of OH molecules around 310 nm were recorded in this direct coupling arrangement.Copper atom spectral absorption around 325 nm of the peripheral cold zones of an intense transient arc was also recorded.
基金supported by the National Key R&D Program of China (2018YFB2101300)。
文摘Radiation source identification plays an important role in non-cooperative communication scene and numerous methods have been proposed in this field. Deep learning has gained popularity in a variety of computer vision tasks. Recently, it has also been successfully applied for radiation source identification.However, training deep neural networks for classification requires a large number of labeled samples, and in non-cooperative applications, it is unrealistic. This paper proposes a method for the unlabeled samples of unknown radiation source. It uses semi-supervised learning to detect unlabeled samples and label new samples automatically. It avoids retraining the neural network with parameter-transfer learning. The results show that compared with the traditional algorithms, the proposed algorithm can offer better accuracy.
文摘An experiment was performed on the Shenguang III prototype laser facility to continue the study on hohlraum radiation source with approximately constant radiation temperature using a continuously shaped laser pulse.A radiation source with a flattop temperature of about130 e V that lasted about 5 ns was obtained.The previous analytical iteration method based on power balance and self-similar solution of ablation was modified taking into account the plasma movements and it was used to design the laser pulse shape for experiment.A comparison between experimental results and simulation is presented and better agreement was achieved using the modified method.Further improvements are discussed.
文摘The undulator is the key component in the compact THz radiation source based on FEL.By matching the adjustable period magnetic field of the undulator with the optical resonance cavity,the passing electron beam will generate coherent radiation with gain,and the radiation power required by THz source can be achieved finally. Compared with the pure permanent magnet type,the hybrid type undulator can decrease the field errors caused by non-homogeneous magnetization of magnetic blocks,and provide higher magnetic field.The conceptual design of a hybrid undulator used for THz radiation source is introduced.We use the FEM code OPERA/TOSCA to simulate 3D magnetic field of the undulator.After optimizing the end structure of the hybrid undulator,the first field integrals is controlled within 0.01Gs.m,and the deviation of the electron beam is less than 0.02mm.
文摘The spatial orientation of optical radiation sources has long been the hot topic in the aerospace and the military applications.Current researches mainly focus on the high precision orientation on the partial field of view.Thus,combination of several partial fields of view is required to achieve orientation when the field of view exceeds 180°,which results in the increase of size,weight,power consumption and the cost.By defining radiation energy and direction of the optical radiation source as a vector and applying the cosine law of radiation and vector theorem,it is shown that the vector can be obtained from unit normal vectors on the three un-coplanar surfaces and from the energy projected by the optical radiation source.Based on this,an orientation method with 360° full field of view by a polyhedron is suggested,the mathematical formula for anti-multipath interference is supposed and the error upper limit is derived.The feasibility and effectiveness of this method are validated by measurements and simulation.An accuracy better than 2.866° and 0.574° is achieved when the ratio of measurement error of energy on arbitrary surface and the true value are 5% and 1%,respectively,given the matrix composed of unit normal vectors on three measurement surfaces is orthogonal.
基金supported by the National Nature Science Foundation of China(No.61274110)
文摘An equivalent radiation source method is proposed to characterize electromagnetic emission and interference of complex three dimensional integrated circuits（IC） in this paper.The method utilizes amplitude-only near-field scanning data to reconstruct an equivalent magnetic dipole array,and the differential evolution optimization algorithm is proposed to extract the locations,orientation and moments of those dipoles.By importing the equivalent dipoles model into a 3D full-wave simulator together with the victim circuit model,the electromagnetic interference issues in mixed RF/digital systems can be well predicted.A commercial IC is used to validate the accuracy and efficiency of this proposed method.The coupled power at the victim antenna port calculated by the equivalent radiation source is compared with the measured data.Good consistency is obtained which confirms the validity and efficiency of the method.
基金supported by the National Natural Science Foundation of China(No.61101186)
文摘For maritime radiation source target tracking in particular electronic counter measures（ECM）environment,there exists two main problems which can deteriorate the tracking performance of traditional approaches.The frst problem is the poor observability of the radiation source.The second one is the measurement uncertainty which includes the uncertainty of the target appearing/disappearing and the detection uncertainty（false and missed detections）.A novel approach is proposed in this paper for tracking maritime radiation source in the presence of measurement uncertainty.To solve the poor observability of maritime radiation source target,using the radiation source motion restriction,the observer altitude information is incorporated into the bearings-only tracking（BOT）method to obtain the unique target localization.Then the two uncertainties in the ECM environment are modeled by the random fnite set（RFS）theory and the Bernoulli fltering method with the observer altitude is adopted to solve the tracking problem of maritime radiation source in such context.Simulation experiments verify the validity of the proposed approach for tracking maritime radiation source,and also demonstrate the superiority of the method compared with the traditional integrated probabilistic data association（IPDA）method.The tracking performance under different conditions,particularly those involving different duration of radiation source opening and switching-off,indicates that the method to solve our problem is robust and effective.
基金project supported by Science and Technology Innovation Fund(Grant No.KDY2019001)Integrated Geophysical Simulation Lab of Chang’an University(Key Laboratory of Chinese Geophysical Society)
文摘In recent years,in order to meet the practical needs of deep edge mine detection with large depth and high precision,transient electromagnetic method(TEM)near emission source detection mode has become an international advanced method(Xue et al.,2020).
文摘The PeTa (Perelman-Tatartchenko) effect is the radiation of the energy of a first-order phase transition during the transition from a less condensed phase to a more condensed one. The effect was independently discovered by M. Perelman and the author of this paper. Six papers on the PeTa effect have been published in this journal over the past nine years. They are devoted to the development of PeTa models to explain the following phenomena: IR radiation from cold surfaces, cavitation luminescence/sonoluminescence (CL/SL), laser-induced bubble luminescence (LIBL), and vapor bubble luminescence (VBL) in underwater geysers. This paper describes the sources of PeTa radiation in the Earth’s atmosphere. These sources of infrared radiation have been investigated by numerous research groups, but their interpretation either does not exist at all, or it is erroneous. The following phenomena are specifically considered: PeTa radiation during the formation of clouds and fog;a pulse laser based on the PeTa radiation;condensation explosions as sources of PaTa radiation;measurement of the concentration of water vapor in the atmosphere using PeTa radiation;atmospheric scintillation of infrared radiation in the atmosphere due to the PeTa effect;PeTa radiation as a source of comfort for the igloo;the influence of PeTa radiation on living organisms;PeTa radiation due to characteristics of tropical storms;PeTa radiation as a possible precursor to earthquakes. The problem of global warming, which worries everyone, as it turns out, is also associated with the PeTa effect.
文摘MCNPX(Monte Carlo N-Particle Transport Code)computer code is used to design a model to CANDU(Canada Deuterium Uranium)reactor core and its shielding system.It is assumed that reactor core is fueled with natural uranium.The core radiation sources are calculated which consider prompt neutrons,neutron induced gamma and prompt gamma radiations.The total neutron flux and dose rate are calculated along the shield and at outer shield points.The results indicated that the major dose rate component at outer shield points is due to neutron induced gamma dose rate(μSv/h).
文摘Swelling property of acrylamide hydrogels,prepared from aqueous solutions of acrylamide monomer havingconcentrations in the range of 10-60 wt% by ray irradiation method using a Co-60 gamma radiation source at dosesranging 1-30.0 kGy,has been investigated under various swelling media.These swelling media were basically solvents(solutions),produced by dissolving methanol,ethanol,glucose,sucrose,sodium chloride and sodium persulfate individuallywith distilled water,and solutions prepared with pHs=3,7 and 10.The investigation was performed in order to observe theeffect of these solvents and pHs as well as the influence of monomer concentrations,radiation doses and times on swellingbehavior of hydrogels.Swelling values were found higher for hydrogels prepared with lower monomer concentrations(ca.20 wt%)and radiation doses(ca.5 kGy)and showed a leveling off tendency within 24 h.The glucose solvent and the buffersolution of pH=10 revealed significant increase of swelling of hydrogels as compared to other solutions.Results areexplained based on crosslinking density in hydrogel,polymer-solvent/polymer-polymer interactions in solutions,permeability of molecules in solutions and ionization capacity of hydrogel in pH.
基金the National Basic Research Program of China(Grant Nos.2012CB825800 and 2009CB930804)the Key Program of the National Natural Science Foundation of China(Grant Nos.10734070 and 10774144)+1 种基金the National Natural Science Foundation of China(Grant Nos.11205189,10979055,31071909,and 31272358)the Knowledge Innovation Program of the Chinese Academy of Sciences(Grant No.KJCX2-YW-N42)
文摘A penetrating view of the three-dimensional nanostructure of female spermatheca and male flagellum in the species Aleochara verna is obtained with 100-nm resolution using a hard X-ray microscope, which provides a fast noninvasive imaging technology for insect morphology. Through introducing Zernike phase contrast and heavy metal staining, images taken at 8 keV displayed sufficient contrast for observing nanoscale fine structures, such as the spermatheca cochleate duct and the subapex of the flagellum, which have some implications for the study of the sperm transfer process and genital evolution in insects. This work shows that both the spatial resolution and the contrast characteristic of hard X-ray microscopy are quite promising for insect morphology studies and, particularly, provide an attractive alternative to the destructive techniques used for investigating internal soft tissues.
基金This project supported by the National Nature Science Foundation of China (No. 10035020 )
文摘Radiation simulation utilizing plasma radiation sources (PRS) generates a large number of undesirable debris, which may damage the expensive diagnosing detectors. An ultra fast shutter (UFS) driven by pulsed high current can erect a physical barrier to the slowly moving debris after allowing the passage of X-ray photons. The UFS consists of a pair of thin metal foils twisting the parallel axes in a Nylon cassette, compressed with an outer magnetic field, generated from a fast capacitor bank, discharging into a single turn loop. A typical capacitor bank is of 7.5μF charging voltages varying from 30 kV to 45 kV, with corresponding currents of approximately 90 kA to140 kA and discharging current periods of approximately 13.1μs. A shutter closing time as fast as 38 microseconds has been obtained with an aluminium foil thickness of 100 micrometers and a cross-sectional area of 15 mm by 20 mm. The design, construction and the expressions of the valve-closing time of the UFS are presented along with the measured results of valve-closing velocities.
基金supported by the National Natural Science Foundation of China(No.91544105,No.41275127,No.U1532137 and No.11575178)。
文摘Vacuum ultraviolet(VUV)photoionization and photodissociation of methylcyclohexane have been studied utilizing a reflectron time-of-flight mass spectrometer(RTOF-MS)with synchrotron radiation source.Photoionization efficiency curves(PIEs)of molecule ion C7H14^+ and fragment ions C7H13^+,C6H11^+,C6H10+,C5H10^+,C5H9^+,C4H8^+,C4H7^+,and C3H5^+ were observed.The ionization energy of methylcyclohexane was measured to be(9.80±0.03)eV,and appearance energies of fragment ions were determined from the PIEs.Optimized structures of transitional states,intermediates and product ions were characterized at the B3LYP/6-31G(d)level and the energies were calculated using G3B3 method.Formation channels of dominating fragment ions were proposed.Intramolecular hydrogen migrations and carbon ring-opening were the foremost processes in fragmentation pathways of methylcyclohexane.
文摘A theoretical model is presented to describe the parametric acoustic field generated by a piston radiator. In the model, the high-frequency primary wave interaction region that is truncated by a low-pass acoustic filter can be viewed as a cylindrical source within the Rayleigh distance of the piston. When the radius of the piston is much smaller than the length of the parametric region, this model is reduced to the Berketey's End-Fire Line Army model. Comparison between numerical calculations and experimental measurement show that the generated parametric sound field (especially near the axis) agrees well with the experiment results.
基金This work is supported by the National Natural Science Foundation of China (59575017) and the Technical Developmental Foundation of Machinery Industry (97JA0104).
文摘The Volume Source Boundary Point Method (VSBPM) is greatly improved so that it will speed up the VSBPM's solution of the acoustic radiation problem caused by the vibrating body. The fundamental solution provided by Helmholtz equation is enforced in a weighted residual sense over a tetrahedron located on the normal line of the boundary node to replace the coefficient matrices of the system equation. Through the enhanced volume source boundary point analysis of various examples and the sound field of a vibrating rectangular box in a semi-anechoic chamber, it has revealed that the calculating speed of the EVSBPM is more than 10 times faster than that of the VSBPM while it works on the aspects of its calculating precision and stability, adaptation to geometric shape of vibrating body as well as its ability to overcome the non-uniqueness problem.
基金funded by the National Natural Science Foundation,China(Grant No.41404045,No.41504047)
文摘The Qianguo Ms5. 8 earthquake swarm of 2013 occurred in Qianguo, Jilin Province, China. There are five earthquakes with Ms ≥5. 0 in the Qianguo earthquake swarm, with magnitudes of Ms 5. 5, Ms 5. 0, Ms 5. 3, Ms 5. 8 and Ms 5. 0. In this study, the far-field seismic radiated energy characteristics of the earthquakes are compared based on the source spectrum and the ground motion spectrum of the earthquake swarm. The ground motion spectrum of the five earthquakes at Changchun seismic station （CN2）, which is the national standard station, is first investigated with the recorded ground motions, and then the far-field seismic radiated energy is calculated and combined with the relationships of the source spectrum to describe the variable characteristics of the Qianguo earthquake swarm. Research results indicate that the second earthquake （No. 2） with Ms5. 0 is the key event of the earthquake swarm, which occurred on October 31, the same day following the first Ms5. 5 earthquake （No.l）. In fact, the magnitude of event No. 2 decreased compared to event No.l, which did not agree with its large far-field seismic radiated energy. It needs to be pointed out that event No. 2 was the turning point event of the Qianguo earthquake swarm, as being a significant transition before the largest Ms5. 8 earthquake.
