Environmentally heterogeneous mountains provide opportunities for rapid diversification and speciation.The family Prunellidae(accentors)is a group of birds comprising primarily mountain specialists that have recently ...Environmentally heterogeneous mountains provide opportunities for rapid diversification and speciation.The family Prunellidae(accentors)is a group of birds comprising primarily mountain specialists that have recently radiated across the Palearctic region.This rapid diversification poses challenges to resolving their phylogeny.Herein we sequenced the complete mitogenomes and estimated the phylogeny using all 12(including 28 individuals)currently recognized species of Prunellidae.We reconstructed the mitochondrial genome phylogeny using 13 protein-coding genes of 12 species and 2 Eurasian Tree Sparrows(Passer montanus).Phylogenetic relationships were estimated using a suite of analyses:maximum likelihood,maximum parsimony and the coalescent-based SVDquartets.Divergence times were estimated by implementing a Bayesian relaxed clock model in BEAST2.Based on the BEAST time-calibrated tree,we implemented an ancestral area reconstruction using RASP v.4.3.Our phylogenies based on the maximum likelihood,maximum parsimony and SVDquartets approaches support a clade of large-sized accentors(subgenus Laiscopus)to be sister to all other accentors with small size(subgenus Prunella).In addition,the trees also support the sister relationship of P.immaculata and P.rubeculoides+P.atrogularis with 100%bootstrap support,but the relationships among the remaining eight species in the Prunella clade are poorly resolved.These species cluster in different positions in the three phylogenetic trees and the nodes are often poorly supported.The five nodes separating the seven species diverged simultaneously within less than half million years(i.e.,between 2.71 and 3.15 million years ago),suggesting that the recent radiation is likely responsible for rampant incomplete lineage sorting and gene tree conflicts.Ancestral area reconstruction indicates a central Palearctic region origin for Prunellidae.Our study highlights that whole mitochondrial genome phylogeny can resolve major lineages within Prunellidae but is not sufficient to fully resolve the relationship among the species in the Prunella clade that almost simultaneously diversify during a short time period.Our results emphasize the challenge to reconstruct reliable phylogenetic relationship in a group of recently radiated species.展开更多
Grafting of acrylic acid (AAc) and acrylamide (AAm) onto preirradiated PP film was performed in aqueous solution of AAc and AAm, respectively. Electron beam accelerator was used as irradiation source. The effect of f...Grafting of acrylic acid (AAc) and acrylamide (AAm) onto preirradiated PP film was performed in aqueous solution of AAc and AAm, respectively. Electron beam accelerator was used as irradiation source. The effect of ferrous sulfate, sodium nitrate, methanol and glucose on the degree of grafting was demonstrated. The function of the different additives was compared by the grafting of different monomers (AAc and AAm). The results show that the four of these additives are elective on the grafting of AAc. Only two of these additives, ferrous sulfate and methanol were effective on the grafting of AAm.展开更多
The energy radiated as seismic waves strongly depends on the fault rupture process associated with rupture speed and dynamic frictional mechanisms involved in the fault slip motion. Following McGarr and Fletcher appro...The energy radiated as seismic waves strongly depends on the fault rupture process associated with rupture speed and dynamic frictional mechanisms involved in the fault slip motion. Following McGarr and Fletcher approach, we derived a physics-based relationship of the weighted average fault slip velocity vs apparent stress, rupture speed and static stress drop based on a dynamic circular fault model. The resultant function can be approximately used to bound near-fault ground motion and seismic energy associated with near-fault coseismic deformation. Fault frictional overshoot and under- shoot mechanisms governed by a simple slip-weakening constitutive relation are included in our consideration by using dy- namic rupture models named as M- and D-models and proposed by Madariaga (1976) and Boatwright. We applied the above function to the 2008 great Wenchuan earthquake and the 1999 Jiji (Chi-Chi) earthquake to infer the near-fault ground motion called slip weighted average particle velocity and obtained that such model-dependent prediction of weighted average ground velocities is consistent to the results derived from the near-fault strong motion observations. Moreover, we compared our re- sults with the results by McGarr and Fletcher approach, and we found that the values of the weighted average particle veloci- ties we obtained for these two earthquakes are generally smaller and closer to the values by direct integration of strong mo- tion recordings of the near-fault particle velocity waveform data. In other words, if this result comes to be true, it would be a straightforward way used to constrain the near-fault ground motion or to estimate source parameters such as rupture speed, static and dynamic stress drops.展开更多
A numerical and experimental study was presented on active control of structurally radiated sound from an elastic cylindrical shell.An analytical model was developed for the active structural acoustic control (ASAC) o...A numerical and experimental study was presented on active control of structurally radiated sound from an elastic cylindrical shell.An analytical model was developed for the active structural acoustic control (ASAC) of the cylindrical shell.Both global and local control strategies were considered.The optimal control forces corresponding to each control strategy were obtained by using the linear quadratic optimal control theory.Numerical simulations were performed to examine and analyze the control performance under different control strategies.The results show that global sound attenuation of the cylindrical shell at resonance frequencies can be achieved by using point force as the control input of the ASAC system.Better control performance can be obtained under the control strategy of minimization of the radiated sound power.However,control spillover may occur at off-resonance frequencies with the control strategy of structural kinetic energy minimization in terms of the radiated sound power.Considerable levels of global sound attenuation can also be achieved in the on-resonance cases with the local control strategy,i.e.,minimization of the mean-square velocity of finite discrete locations.An ASAC experiment using an FXLMS algorithm was implemented,agreement was observed between the numerical and experimental results,and successful attenuation of structural vibration and radiated sound was achieved.展开更多
The double-peak characteristic of underwater radiated noise in the near field on top of the target submarine was analyzed in depth on the basis of submarine test data on the sea. The contribution of three major noise ...The double-peak characteristic of underwater radiated noise in the near field on top of the target submarine was analyzed in depth on the basis of submarine test data on the sea. The contribution of three major noise sources to the radiated noise of a submarine were compared and analyzed, and emphasis was put on the original source, production mechanism, and their correlative characteristics. On the basis of analysis on underwater tracking and pass through characteristics of the target submarine, the double-peak phenomenon was reasonably interpreted. Furthermore, the correctness of the theoretical interpretation was verified adequately in real submarine tests. The double-peak phenomenon indicates that the space distributing character on submarine radiated noise are both asymmetrical with time and space, whereas that is provided with directivity. Studying the double-peak phenomenon in depth has important reference value and meaning in engineering practice for understanding the underwater radiated noise field of submarines.展开更多
To improve the ability of detecting underwater targets under strong wideband interference environment,an efficient method of line spectrum extraction is proposed,which fully utilizes the feature of the target spectrum...To improve the ability of detecting underwater targets under strong wideband interference environment,an efficient method of line spectrum extraction is proposed,which fully utilizes the feature of the target spectrum that the high intense and stable line spectrum is superimposed on the wide continuous spectrum.This method modifies the traditional beam forming algorithm by calculating and fusing the beam forming results at multi-frequency band and multi-azimuth interval,showing an excellent way to extract the line spectrum when the interference and the target are not in the same azimuth interval simultaneously.Statistical efficiency of the estimated azimuth variance and corresponding power of the line spectrum band depends on the line spectra ratio(LSR)of the line spectrum.The change laws of the output signal to noise ratio(SNR)with the LSR,the input SNR,the integration time and the filtering bandwidth of different algorithms bring the selection principle of the critical LSR.As the basis,the detection gain of wideband energy integration and the narrowband line spectrum algorithm are theoretically analyzed.The simulation detection gain demonstrates a good match with the theoretical model.The application conditions of all methods are verified by the receiver operating characteristic(ROC)curve and experimental data from Qiandao Lake.In fact,combining the two methods for target detection reduces the missed detection rate.The proposed post-processing method in2-dimension with the Kalman filter in the time dimension and the background equalization algorithm in the azimuth dimension makes use of the strong correlation between adjacent frames,could further remove background fluctuation and improve the display effect.展开更多
In the mining process of deep metal mines,diff erent types of rock mass instability failures are caused by strong mining disturbance.It is beneficial to master the fracture mechanism of rock mass in time to effectivel...In the mining process of deep metal mines,diff erent types of rock mass instability failures are caused by strong mining disturbance.It is beneficial to master the fracture mechanism of rock mass in time to effectively prevent and control the ground pressure disasters.Microseismic signals are generated by the propagation and expansion of cracks inside the rock mass that contain plentiful information about the structural changes of rock mass.The ratio of the radiated energy of S and P waves(Es/Ep)of microseismic events can fast and eff ectively calculate the rock fracture mechanism,which is widely used for ground pressure hazard risk assessment.In this paper,this method was used to analyze the fracture mechanism of rock mass around deep stope in Hongtoushan copper mine and Ashele copper mine.Furthermore,the spatial distribution characteristics and proportion changes of microseismic events with diff erent fracture mechanisms along with the mining process were studied.The results show that tensile cracks play a dominant role,accounting for 62%of the total events,during non-shear fracturing of the rock mass caused by the stoping unloading eff ect,while shear cracks occupy 68%of the total events during orebody slip failure.When the physical and mechanical properties of the orebody and rock mass are signifi cantly diff erent,slip failure along their contact zone is prone to occur under blasting disturbance.During deep mining,it is necessary to control the exposed area of the roof by each stoping,especially during the earlier mining stage,to avoid tensile stress concentration.The temporal and spatial variation of tension cracks and shear cracks induced by roof damage obtained in this paper can guide the prevention and control of ground pressure disasters in deep mining eff ectively.展开更多
A type of silicon detector known as AXUV (absolute extreme ultraviolet) photodiodes is successfully used to measure the radiated power in EAST. The detector is characterized by compact structure, fast temporal respo...A type of silicon detector known as AXUV (absolute extreme ultraviolet) photodiodes is successfully used to measure the radiated power in EAST. The detector is characterized by compact structure, fast temporal response (〈0.5 s) and flat spectral sensitivity in the range from ultra-violet to X-ray. Two 16-channel AXUV arrays are installed in EAST to view the whole poloidal cross-section of plasma. Based on the diagnostic system, typical radiation distributions for both limiter and divertor plasma are obtained and compared. As divertor detachment occurs, the radiation distribution in X-point region is observed to vary distinctly. The total radiation power losses in discharges with different plasma parameters are briefly analyzed.展开更多
The current article discusses the heat transfer characteristics of ferromagnetic liquid over an elastic surface with the thermal radiation and non-Fourier heat flux.In most of the existing studies,the heat flux is con...The current article discusses the heat transfer characteristics of ferromagnetic liquid over an elastic surface with the thermal radiation and non-Fourier heat flux.In most of the existing studies,the heat flux is considered as constant,but whereas we incorporated the non-Fourier flux to get the exact performance of the flow.Also,we excluded the PWT and PHF cases to control the boundary layer of the flow.The governing equations related to our contemplate are changed into non-linear ordinary differential equations(ODE’s)by utilizing appropriate similarity changes,which are at the point enlightened by Runge–Kutta based shooting approach.The equations are broken down concerning boundary conditions and to be explained prescribed wall temperature(PWT)and prescribed heat flux(PHF)cases.The impacts of diverse non-dimensional physical parameters on velocity and temperature profiles are laid out graphically.Also,the assortment of skin friction and local Nusselt number for both PWT and PHF cases for various assessments of non-dimensional parameters have been sorted out.Towards the wrap-up of the examination,we suspect that the friction factor coefficient is higher in the PWT case compared to the PHF case.This result helps to conclude that the flux conditions are useful for cooling applications.展开更多
Ultrawideband electromagnetic pulses with high amplitude and short duration are reported to affect several aspects of cell physiology. They are usually delivered to the living material through electrodes in small dedi...Ultrawideband electromagnetic pulses with high amplitude and short duration are reported to affect several aspects of cell physiology. They are usually delivered to the living material through electrodes in small dedicated chambers. Here we showed, using a totally different experimental setup, that radiated EM pulses illuminating the living material through a specialized antenna (without any direct contact) are able to trigger a rapid release of ATP in cultured murine cells that was concomitant with a drop of intracellular AEC. Despite this rapid and strong response, we found that cell viability and clonogenicity were only slightly affected by the EMF exposure.展开更多
The air breakdown in the high-power antenna near-field region limits the enhancement of the radiated power. A model coupling the field equivalent principle and the electron number density equation is presented to stud...The air breakdown in the high-power antenna near-field region limits the enhancement of the radiated power. A model coupling the field equivalent principle and the electron number density equation is presented to study the breakdown process in the near-field region of the circular aperture antenna at atmospheric pressure. Simulation results show that, although the electric field in the near-field region is nonuniform, the electron diffusion has small influence on the breakdown process when the initial electron number density is uniform in space. The field magnitude distribution on the aperture plays an important role in the maximum radiated power above which the air breakdown occurs. The maximum radiated power also depends on the phase difference of the fields at the center and edge of the aperture, especially for the uniform field magnitude distribution.展开更多
In this paper, analytical formularions of radiated sound pressure of ring-stiffenedcylindrical shells in fluid medium are derived by means of Hamilton's principleHuygens principle and Green function . These formul...In this paper, analytical formularions of radiated sound pressure of ring-stiffenedcylindrical shells in fluid medium are derived by means of Hamilton's principleHuygens principle and Green function . These formulations Can be used to compute the sound pressure of the shell's surface nearfield and farfield.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
The problem of excessive radiated emission for a certain type of laser scanner is discussed in this paper.Firstly,the frequency characteristics of the laser scanner can be obtained by traditional test methods.Accordin...The problem of excessive radiated emission for a certain type of laser scanner is discussed in this paper.Firstly,the frequency characteristics of the laser scanner can be obtained by traditional test methods.According to the frequency and electronic equipment characteristics,the interference source can be estimated and established.Then based upon analysis,modified methods are proposed.By applying the above methods,the interference source can be identified and the amount of radiated emission from the scanner can be reduced effectively.Finally,the scanner can op erate in a compatible manner with other electronic systems at the same time.The above methods can provide a reference for electronic equipment design ensuring electromagnetic compatibility and passing the radiated emission test.展开更多
As per the entail in wireless communication, the ever increasing switching speeds of digital devices pose significant challenges. Signal quality is more important for high speed products and the signal integrity ...As per the entail in wireless communication, the ever increasing switching speeds of digital devices pose significant challenges. Signal quality is more important for high speed products and the signal integrity must ensure reliable transmission where signal integrity is a measure of the quality of an electrical signal. A high speed differential signal will result in signal integrity issues such as crosstalk and radiated emission. One of the solutions to suppress radiated emission is defected ground pattern. This paper introduces a novel trident incurvature shaped defected ground structure to suppress radiated emission that arises in high speed differential signal. The proposed defected ground structure is implemented using Ansoft HFSS simulation tool and its performance is quantified in terms of scattering parameters. The proposed trident incurvature shaped defected ground pattern reduces near end coupling and far end coupling by more than 6 dB and 2 dB respectively. It also provides better return loss and insertion loss in the frequency range 1 - 6 GHz.展开更多
In this study, to explore the radiation protection effects of Lyophyllum Decastes Sing (LDS), a hot distilled-water extract of LDS was orally administered at a dosage of 250mg/kg every other day for a period of 2 we...In this study, to explore the radiation protection effects of Lyophyllum Decastes Sing (LDS), a hot distilled-water extract of LDS was orally administered at a dosage of 250mg/kg every other day for a period of 2 weeks in irradiated mice. An automatic blood cell counter was used to measure white blood cells (lymphocytes, monocyte, and granulocytes) one day before X-ray irradiation, and 3 hours, 12 hours, 24 hours, 3 days, 7 days, 15 days and 30 days after irradiation. The Dunnett test was used to examine statistical significance of differences. The peripheral blood cell counts in the Lyophyllum-administered non-irradiation group revealed an increase in the numbers of ieukocytes, lymphocytes and monocytes. For 2 Gy whole body radiation, a significant statistical difference was found between the X-ray group and the Lyophyllum plus X-ray group in the numbers of leukocytes, lymphocytes and monocytes. The results suggest that Lyophyllum restrains blood cell-count falling after irradiation, which is probably mediated at least in part by hemopoietic function, and NK and LAK activities seems to play a role in preventing secondary irffections associated with irradiation.展开更多
The quality of dark output images from the CMOS (complementarymetal oxide semiconductor) black and white (B & W) digital imagesensors captured before and after γ-ray irradiation was studied. Thecharacteristic par...The quality of dark output images from the CMOS (complementarymetal oxide semiconductor) black and white (B & W) digital imagesensors captured before and after γ-ray irradiation was studied. Thecharacteristic parameters of the dark output images captured atdifferent radiation dose, e.g. average brightness and itsnon-uniformity of dark out- put images, were analyzed by our testsoftware. The primary explanation for the change of the parameterswith the radi- ation dose was given.展开更多
In order to investigate the influence of radiation therapy after the treatment of maxillary implant-supported prostheses, 27 patients received a total of 131 implants in maxilla after oral cancer treatment and/or reco...In order to investigate the influence of radiation therapy after the treatment of maxillary implant-supported prostheses, 27 patients received a total of 131 implants in maxilla after oral cancer treatment and/or reconstructive surgery. Among them, 25 received maxillary implant-supported prostheses. The cumulative survival rates of implants and prostheses were evaluated by the product-limit-estimates method according to Kaplan-Meier. The cumulative survival rate of implants and prostheses in irradiated patients was compared with that in non-irradiated patients by statistical Log-rank test. The results showed that 112 implants were observed after implant loading. The implants cumulative survival rate was approximately 65 % for overall patients. The cumulative prosthesis successful rate was approximately 88 % for all 25 patients. Log-rank test analysis revealed that there was a significant difference in cumulative implants survival rates between non-irradiated and irradiated maxillary bone (P<0. 01). It was concluded that the implants and prostheses in irradiated patients have significantly lower survival rates than in non-irradiated patients.展开更多
The nonlinear radiated waves generated by a structure in forced motion, are simulated numerically based on the potential theory. A fully nonlinear numerical model is developed by using a higher-order boundary element ...The nonlinear radiated waves generated by a structure in forced motion, are simulated numerically based on the potential theory. A fully nonlinear numerical model is developed by using a higher-order boundary element method (HOBEM). In this model, the instantaneous body position and the transient free surface are updated at each time step. A Lagrangian technique is employed as the time marching scheme on the free surface. The mesh regridding and interpolation methods are adopted to deal with the possible numerical instability. Several auxiliary functions are proposed to calculate the wave loads indirectly, instead of directly predicting the temporal derivative of the velocity potential. Numerical experiments are carried out to simulate the heave motions of a submerged sphere in infinite water depth, the heave and pitch motions of a truncated flared cylinder in finite depth. The results are verified against the published numerical results to ensure the effectiveness of the proposed model. Moreover, a series of higher harmonic waves and force components are obtained by the Fourier transformation to investigate the nonlinear effect of oscillation frequency. The difference among fully nonlinear, body-nonlinear and linear results is analyzed. It is found that the nonlinearity due to free surface and body surface has significant influences on the numerical results of the radiated waves and forces.展开更多
Vacuum ultraviolet radiation of Upilex-S polyimide film 25 μm thick was performed using a gas jet type of vacuum ultraviolet simulator which gives unfixed wavelength from 5 nm to 200 nm.Nanoparticles redeposited on t...Vacuum ultraviolet radiation of Upilex-S polyimide film 25 μm thick was performed using a gas jet type of vacuum ultraviolet simulator which gives unfixed wavelength from 5 nm to 200 nm.Nanoparticles redeposited on the films were observed and the nanoparticles formed on the surface consist mainly of carbon clusters.Changes in the composition and the chemical characteristics of film surface after radiation were identified by X-ray photoelectron spectroscopy(XPS).Relative O content in the radiated area was found to be higher,while N content was lower than in the pristine area.This indicates that Upilex-S polyimide film releases N atoms as volatile species.And the C1s,O1s envelopes were fitted using Multipak Spectrum software.The surface morphologies on iradiated area were examined by Atomic Force Microscope(AFM).Pieces of radiant products protrude from the eradiated surface,leading to considerable roughness for the iradiated area.And the surface transmittance of Upilex-S film after radiation reduces.展开更多
基金funded by the National Natural Science Foundation of China(NSFC32020103005)the Third Xinjiang Scientific Expedition and Research(XIKK)(2022xjkk0205)Second Tibetan Plateau Scientific Expedition and Research(2019QZKK0501)。
文摘Environmentally heterogeneous mountains provide opportunities for rapid diversification and speciation.The family Prunellidae(accentors)is a group of birds comprising primarily mountain specialists that have recently radiated across the Palearctic region.This rapid diversification poses challenges to resolving their phylogeny.Herein we sequenced the complete mitogenomes and estimated the phylogeny using all 12(including 28 individuals)currently recognized species of Prunellidae.We reconstructed the mitochondrial genome phylogeny using 13 protein-coding genes of 12 species and 2 Eurasian Tree Sparrows(Passer montanus).Phylogenetic relationships were estimated using a suite of analyses:maximum likelihood,maximum parsimony and the coalescent-based SVDquartets.Divergence times were estimated by implementing a Bayesian relaxed clock model in BEAST2.Based on the BEAST time-calibrated tree,we implemented an ancestral area reconstruction using RASP v.4.3.Our phylogenies based on the maximum likelihood,maximum parsimony and SVDquartets approaches support a clade of large-sized accentors(subgenus Laiscopus)to be sister to all other accentors with small size(subgenus Prunella).In addition,the trees also support the sister relationship of P.immaculata and P.rubeculoides+P.atrogularis with 100%bootstrap support,but the relationships among the remaining eight species in the Prunella clade are poorly resolved.These species cluster in different positions in the three phylogenetic trees and the nodes are often poorly supported.The five nodes separating the seven species diverged simultaneously within less than half million years(i.e.,between 2.71 and 3.15 million years ago),suggesting that the recent radiation is likely responsible for rampant incomplete lineage sorting and gene tree conflicts.Ancestral area reconstruction indicates a central Palearctic region origin for Prunellidae.Our study highlights that whole mitochondrial genome phylogeny can resolve major lineages within Prunellidae but is not sufficient to fully resolve the relationship among the species in the Prunella clade that almost simultaneously diversify during a short time period.Our results emphasize the challenge to reconstruct reliable phylogenetic relationship in a group of recently radiated species.
文摘Grafting of acrylic acid (AAc) and acrylamide (AAm) onto preirradiated PP film was performed in aqueous solution of AAc and AAm, respectively. Electron beam accelerator was used as irradiation source. The effect of ferrous sulfate, sodium nitrate, methanol and glucose on the degree of grafting was demonstrated. The function of the different additives was compared by the grafting of different monomers (AAc and AAm). The results show that the four of these additives are elective on the grafting of AAc. Only two of these additives, ferrous sulfate and methanol were effective on the grafting of AAm.
基金supported by the Knowledge Innovation Program of Chinese Academy of Sciences (KZCX2-YW-Q08-2)One-Hundred-Individual Program of Chinese Academy of Sciences
文摘The energy radiated as seismic waves strongly depends on the fault rupture process associated with rupture speed and dynamic frictional mechanisms involved in the fault slip motion. Following McGarr and Fletcher approach, we derived a physics-based relationship of the weighted average fault slip velocity vs apparent stress, rupture speed and static stress drop based on a dynamic circular fault model. The resultant function can be approximately used to bound near-fault ground motion and seismic energy associated with near-fault coseismic deformation. Fault frictional overshoot and under- shoot mechanisms governed by a simple slip-weakening constitutive relation are included in our consideration by using dy- namic rupture models named as M- and D-models and proposed by Madariaga (1976) and Boatwright. We applied the above function to the 2008 great Wenchuan earthquake and the 1999 Jiji (Chi-Chi) earthquake to infer the near-fault ground motion called slip weighted average particle velocity and obtained that such model-dependent prediction of weighted average ground velocities is consistent to the results derived from the near-fault strong motion observations. Moreover, we compared our re- sults with the results by McGarr and Fletcher approach, and we found that the values of the weighted average particle veloci- ties we obtained for these two earthquakes are generally smaller and closer to the values by direct integration of strong mo- tion recordings of the near-fault particle velocity waveform data. In other words, if this result comes to be true, it would be a straightforward way used to constrain the near-fault ground motion or to estimate source parameters such as rupture speed, static and dynamic stress drops.
基金Supported by the National Natural Science Foundation of China (No.10802024)Research Fund for the Doctoral Program of Higher Education of China (No. 200802171009)+2 种基金the Natural Science Foundation of Heilongjiang Province (No.E200944)Innovative Talents Fund of Harbin (No.2009RFQXG211)Fundamental Research Fund of HEU (No. HEUFT08003)
文摘A numerical and experimental study was presented on active control of structurally radiated sound from an elastic cylindrical shell.An analytical model was developed for the active structural acoustic control (ASAC) of the cylindrical shell.Both global and local control strategies were considered.The optimal control forces corresponding to each control strategy were obtained by using the linear quadratic optimal control theory.Numerical simulations were performed to examine and analyze the control performance under different control strategies.The results show that global sound attenuation of the cylindrical shell at resonance frequencies can be achieved by using point force as the control input of the ASAC system.Better control performance can be obtained under the control strategy of minimization of the radiated sound power.However,control spillover may occur at off-resonance frequencies with the control strategy of structural kinetic energy minimization in terms of the radiated sound power.Considerable levels of global sound attenuation can also be achieved in the on-resonance cases with the local control strategy,i.e.,minimization of the mean-square velocity of finite discrete locations.An ASAC experiment using an FXLMS algorithm was implemented,agreement was observed between the numerical and experimental results,and successful attenuation of structural vibration and radiated sound was achieved.
基金Supported by the Navy Equipment Advanced Research Project under Grant No. 40113070203
文摘The double-peak characteristic of underwater radiated noise in the near field on top of the target submarine was analyzed in depth on the basis of submarine test data on the sea. The contribution of three major noise sources to the radiated noise of a submarine were compared and analyzed, and emphasis was put on the original source, production mechanism, and their correlative characteristics. On the basis of analysis on underwater tracking and pass through characteristics of the target submarine, the double-peak phenomenon was reasonably interpreted. Furthermore, the correctness of the theoretical interpretation was verified adequately in real submarine tests. The double-peak phenomenon indicates that the space distributing character on submarine radiated noise are both asymmetrical with time and space, whereas that is provided with directivity. Studying the double-peak phenomenon in depth has important reference value and meaning in engineering practice for understanding the underwater radiated noise field of submarines.
基金supported by the National Natural Science Foundation of China(51875535)the Natural Science Foundation for Young Scientists of Shanxi Province(201701D221017,201901D211242)。
文摘To improve the ability of detecting underwater targets under strong wideband interference environment,an efficient method of line spectrum extraction is proposed,which fully utilizes the feature of the target spectrum that the high intense and stable line spectrum is superimposed on the wide continuous spectrum.This method modifies the traditional beam forming algorithm by calculating and fusing the beam forming results at multi-frequency band and multi-azimuth interval,showing an excellent way to extract the line spectrum when the interference and the target are not in the same azimuth interval simultaneously.Statistical efficiency of the estimated azimuth variance and corresponding power of the line spectrum band depends on the line spectra ratio(LSR)of the line spectrum.The change laws of the output signal to noise ratio(SNR)with the LSR,the input SNR,the integration time and the filtering bandwidth of different algorithms bring the selection principle of the critical LSR.As the basis,the detection gain of wideband energy integration and the narrowband line spectrum algorithm are theoretically analyzed.The simulation detection gain demonstrates a good match with the theoretical model.The application conditions of all methods are verified by the receiver operating characteristic(ROC)curve and experimental data from Qiandao Lake.In fact,combining the two methods for target detection reduces the missed detection rate.The proposed post-processing method in2-dimension with the Kalman filter in the time dimension and the background equalization algorithm in the azimuth dimension makes use of the strong correlation between adjacent frames,could further remove background fluctuation and improve the display effect.
基金the National Key Research and Development Program of China(2017YFC0602904)the National Natural Science Foundation of China(51974059)the Fundamental Research Funds for the Central Universities(N180115010).
文摘In the mining process of deep metal mines,diff erent types of rock mass instability failures are caused by strong mining disturbance.It is beneficial to master the fracture mechanism of rock mass in time to effectively prevent and control the ground pressure disasters.Microseismic signals are generated by the propagation and expansion of cracks inside the rock mass that contain plentiful information about the structural changes of rock mass.The ratio of the radiated energy of S and P waves(Es/Ep)of microseismic events can fast and eff ectively calculate the rock fracture mechanism,which is widely used for ground pressure hazard risk assessment.In this paper,this method was used to analyze the fracture mechanism of rock mass around deep stope in Hongtoushan copper mine and Ashele copper mine.Furthermore,the spatial distribution characteristics and proportion changes of microseismic events with diff erent fracture mechanisms along with the mining process were studied.The results show that tensile cracks play a dominant role,accounting for 62%of the total events,during non-shear fracturing of the rock mass caused by the stoping unloading eff ect,while shear cracks occupy 68%of the total events during orebody slip failure.When the physical and mechanical properties of the orebody and rock mass are signifi cantly diff erent,slip failure along their contact zone is prone to occur under blasting disturbance.During deep mining,it is necessary to control the exposed area of the roof by each stoping,especially during the earlier mining stage,to avoid tensile stress concentration.The temporal and spatial variation of tension cracks and shear cracks induced by roof damage obtained in this paper can guide the prevention and control of ground pressure disasters in deep mining eff ectively.
基金supported by National Natural Science Foundation of China (No. 10935004)National Magnetic Confinement Fusion Science Program of China (Nos. 2010GB106000, 2010GB106004)
文摘A type of silicon detector known as AXUV (absolute extreme ultraviolet) photodiodes is successfully used to measure the radiated power in EAST. The detector is characterized by compact structure, fast temporal response (〈0.5 s) and flat spectral sensitivity in the range from ultra-violet to X-ray. Two 16-channel AXUV arrays are installed in EAST to view the whole poloidal cross-section of plasma. Based on the diagnostic system, typical radiation distributions for both limiter and divertor plasma are obtained and compared. As divertor detachment occurs, the radiation distribution in X-point region is observed to vary distinctly. The total radiation power losses in discharges with different plasma parameters are briefly analyzed.
文摘The current article discusses the heat transfer characteristics of ferromagnetic liquid over an elastic surface with the thermal radiation and non-Fourier heat flux.In most of the existing studies,the heat flux is considered as constant,but whereas we incorporated the non-Fourier flux to get the exact performance of the flow.Also,we excluded the PWT and PHF cases to control the boundary layer of the flow.The governing equations related to our contemplate are changed into non-linear ordinary differential equations(ODE’s)by utilizing appropriate similarity changes,which are at the point enlightened by Runge–Kutta based shooting approach.The equations are broken down concerning boundary conditions and to be explained prescribed wall temperature(PWT)and prescribed heat flux(PHF)cases.The impacts of diverse non-dimensional physical parameters on velocity and temperature profiles are laid out graphically.Also,the assortment of skin friction and local Nusselt number for both PWT and PHF cases for various assessments of non-dimensional parameters have been sorted out.Towards the wrap-up of the examination,we suspect that the friction factor coefficient is higher in the PWT case compared to the PHF case.This result helps to conclude that the flux conditions are useful for cooling applications.
文摘Ultrawideband electromagnetic pulses with high amplitude and short duration are reported to affect several aspects of cell physiology. They are usually delivered to the living material through electrodes in small dedicated chambers. Here we showed, using a totally different experimental setup, that radiated EM pulses illuminating the living material through a specialized antenna (without any direct contact) are able to trigger a rapid release of ATP in cultured murine cells that was concomitant with a drop of intracellular AEC. Despite this rapid and strong response, we found that cell viability and clonogenicity were only slightly affected by the EMF exposure.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61501358,11622542,61431010,and 61627901)the Fundamental Research Funds for the Central Universities,China
文摘The air breakdown in the high-power antenna near-field region limits the enhancement of the radiated power. A model coupling the field equivalent principle and the electron number density equation is presented to study the breakdown process in the near-field region of the circular aperture antenna at atmospheric pressure. Simulation results show that, although the electric field in the near-field region is nonuniform, the electron diffusion has small influence on the breakdown process when the initial electron number density is uniform in space. The field magnitude distribution on the aperture plays an important role in the maximum radiated power above which the air breakdown occurs. The maximum radiated power also depends on the phase difference of the fields at the center and edge of the aperture, especially for the uniform field magnitude distribution.
文摘In this paper, analytical formularions of radiated sound pressure of ring-stiffenedcylindrical shells in fluid medium are derived by means of Hamilton's principleHuygens principle and Green function . These formulations Can be used to compute the sound pressure of the shell's surface nearfield and farfield.
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.
文摘The problem of excessive radiated emission for a certain type of laser scanner is discussed in this paper.Firstly,the frequency characteristics of the laser scanner can be obtained by traditional test methods.According to the frequency and electronic equipment characteristics,the interference source can be estimated and established.Then based upon analysis,modified methods are proposed.By applying the above methods,the interference source can be identified and the amount of radiated emission from the scanner can be reduced effectively.Finally,the scanner can op erate in a compatible manner with other electronic systems at the same time.The above methods can provide a reference for electronic equipment design ensuring electromagnetic compatibility and passing the radiated emission test.
文摘As per the entail in wireless communication, the ever increasing switching speeds of digital devices pose significant challenges. Signal quality is more important for high speed products and the signal integrity must ensure reliable transmission where signal integrity is a measure of the quality of an electrical signal. A high speed differential signal will result in signal integrity issues such as crosstalk and radiated emission. One of the solutions to suppress radiated emission is defected ground pattern. This paper introduces a novel trident incurvature shaped defected ground structure to suppress radiated emission that arises in high speed differential signal. The proposed defected ground structure is implemented using Ansoft HFSS simulation tool and its performance is quantified in terms of scattering parameters. The proposed trident incurvature shaped defected ground pattern reduces near end coupling and far end coupling by more than 6 dB and 2 dB respectively. It also provides better return loss and insertion loss in the frequency range 1 - 6 GHz.
文摘In this study, to explore the radiation protection effects of Lyophyllum Decastes Sing (LDS), a hot distilled-water extract of LDS was orally administered at a dosage of 250mg/kg every other day for a period of 2 weeks in irradiated mice. An automatic blood cell counter was used to measure white blood cells (lymphocytes, monocyte, and granulocytes) one day before X-ray irradiation, and 3 hours, 12 hours, 24 hours, 3 days, 7 days, 15 days and 30 days after irradiation. The Dunnett test was used to examine statistical significance of differences. The peripheral blood cell counts in the Lyophyllum-administered non-irradiation group revealed an increase in the numbers of ieukocytes, lymphocytes and monocytes. For 2 Gy whole body radiation, a significant statistical difference was found between the X-ray group and the Lyophyllum plus X-ray group in the numbers of leukocytes, lymphocytes and monocytes. The results suggest that Lyophyllum restrains blood cell-count falling after irradiation, which is probably mediated at least in part by hemopoietic function, and NK and LAK activities seems to play a role in preventing secondary irffections associated with irradiation.
基金the National Natural Science Foundation of China (No.10075029).
文摘The quality of dark output images from the CMOS (complementarymetal oxide semiconductor) black and white (B & W) digital imagesensors captured before and after γ-ray irradiation was studied. Thecharacteristic parameters of the dark output images captured atdifferent radiation dose, e.g. average brightness and itsnon-uniformity of dark out- put images, were analyzed by our testsoftware. The primary explanation for the change of the parameterswith the radi- ation dose was given.
文摘In order to investigate the influence of radiation therapy after the treatment of maxillary implant-supported prostheses, 27 patients received a total of 131 implants in maxilla after oral cancer treatment and/or reconstructive surgery. Among them, 25 received maxillary implant-supported prostheses. The cumulative survival rates of implants and prostheses were evaluated by the product-limit-estimates method according to Kaplan-Meier. The cumulative survival rate of implants and prostheses in irradiated patients was compared with that in non-irradiated patients by statistical Log-rank test. The results showed that 112 implants were observed after implant loading. The implants cumulative survival rate was approximately 65 % for overall patients. The cumulative prosthesis successful rate was approximately 88 % for all 25 patients. Log-rank test analysis revealed that there was a significant difference in cumulative implants survival rates between non-irradiated and irradiated maxillary bone (P<0. 01). It was concluded that the implants and prostheses in irradiated patients have significantly lower survival rates than in non-irradiated patients.
基金supported by the National Natural Science Foundation of China(51222902,51221961,and 51379032)the Program for New Century Excellent Talents in University(NCET-130076)+2 种基金The Fundamental Research Fund for the Central University(HEUCF140103)The Open Fund of State Key Laboratory of Coastal and Offshore Engineering(LP1407)the Lloyd’s Register Foundation (LRF) through the Joint Centre Involving University College London,Shanghai Jiaotong University and Harbin Engineering University
文摘The nonlinear radiated waves generated by a structure in forced motion, are simulated numerically based on the potential theory. A fully nonlinear numerical model is developed by using a higher-order boundary element method (HOBEM). In this model, the instantaneous body position and the transient free surface are updated at each time step. A Lagrangian technique is employed as the time marching scheme on the free surface. The mesh regridding and interpolation methods are adopted to deal with the possible numerical instability. Several auxiliary functions are proposed to calculate the wave loads indirectly, instead of directly predicting the temporal derivative of the velocity potential. Numerical experiments are carried out to simulate the heave motions of a submerged sphere in infinite water depth, the heave and pitch motions of a truncated flared cylinder in finite depth. The results are verified against the published numerical results to ensure the effectiveness of the proposed model. Moreover, a series of higher harmonic waves and force components are obtained by the Fourier transformation to investigate the nonlinear effect of oscillation frequency. The difference among fully nonlinear, body-nonlinear and linear results is analyzed. It is found that the nonlinearity due to free surface and body surface has significant influences on the numerical results of the radiated waves and forces.
基金This work is financially supported by Development Program for Outstanding Young Teachers in Harbin Institute of Technology(No HIT2006 32)
文摘Vacuum ultraviolet radiation of Upilex-S polyimide film 25 μm thick was performed using a gas jet type of vacuum ultraviolet simulator which gives unfixed wavelength from 5 nm to 200 nm.Nanoparticles redeposited on the films were observed and the nanoparticles formed on the surface consist mainly of carbon clusters.Changes in the composition and the chemical characteristics of film surface after radiation were identified by X-ray photoelectron spectroscopy(XPS).Relative O content in the radiated area was found to be higher,while N content was lower than in the pristine area.This indicates that Upilex-S polyimide film releases N atoms as volatile species.And the C1s,O1s envelopes were fitted using Multipak Spectrum software.The surface morphologies on iradiated area were examined by Atomic Force Microscope(AFM).Pieces of radiant products protrude from the eradiated surface,leading to considerable roughness for the iradiated area.And the surface transmittance of Upilex-S film after radiation reduces.