This study explores the impact of bismuth oxide(Bi_(2)O_(3))on the optical and radiation shielding properties of transparent,lead-free thulium-doped bismuth borotellurite radiation shielding glass.The investigated gla...This study explores the impact of bismuth oxide(Bi_(2)O_(3))on the optical and radiation shielding properties of transparent,lead-free thulium-doped bismuth borotellurite radiation shielding glass.The investigated glass composition follows the formula[(TeO_(2))_(75)(B_(2)O_(3))_(25)]_(98-x)(Bi_(2)O_(3))_x[Tm_(2)O_(3)]_(2),where x=0 mol%,5 mol%,10 mol%,15 mol%,20 mol%,25 mol%,and 30 mol%.All glass samples remain transparent,with an optical bandgap(E_(opt))exceeding 3.1 e V,ensuring visible light transmission.Radiation shielding data from Phy-X and XCom reveal interactions of the photoelectric effect,Compton scattering,and pair production,with minimal relative difference in mass attenuation coefficient(MAC)which is between0.05 and 0.56.At 0.662 Me V photon energy,the 20 mol%and 25 mol%Bi_(2)O_(3)glasses exhibit significantly higher Phy-X MAC values than other samples,except RS 520 glass,which contains 71%Pb O.Despite incorporating only up to 25 mol%Bi_(2)O_(3),these glasses outperform others in density,half-value layer(HVL),and mean free path(MFP).Correlating E_(opt)and MAC,the 20 mol%Bi_(2)O_(3)glass is the best candidate for transparent radiation shielding glass due to its wide optical bandgap which prevents ionization of trapped holes.Significantly,the linkage between MFP and molar refraction was also discovered based on the particle size influence on both parameters.展开更多
In decades,the battlefield environment is becoming more and more complex with plenty of electronic equipments.Thus,in order to improve the survivability of radar sensors and satisfy the requirement of maneuvering targ...In decades,the battlefield environment is becoming more and more complex with plenty of electronic equipments.Thus,in order to improve the survivability of radar sensors and satisfy the requirement of maneuvering target tracking with a low probability of intercept,a non-myopic scheduling is proposed to minimize the radiation cost with tracking accuracy constraint.At first,the scheduling problem is formulated as a partially observable Markov decision process(POMDP).Then the tracking accuracy and radiation cost over the future finite time horizon are predicted by the posterior carmer-rao lower bound(PCRLB) and the hidden Markov model filter,respectively.Finally,the proposed scheduling is implemented efficiently by utilizing the branch and bound(B&B) pruning algorithm.Simulation results show that the performance of maneuvering target tracking was improved by the improved interacting multiple model(IMM),and the scheduler time and maximum memory consumption were significant reduced by the present B&B pruning algorithm without losing the optimal solution.展开更多
The main goal of this paper is to investigate natural convective heat transfer and flow characteristics of non-Newtonian nanofluid streaming between two infinite vertical flat plates in the presence of magnetic field ...The main goal of this paper is to investigate natural convective heat transfer and flow characteristics of non-Newtonian nanofluid streaming between two infinite vertical flat plates in the presence of magnetic field and thermal radiation.Initially,a similarity transformation is used to convert momentum and energy conservation equations in partial differential forms into non-linear ordinary differential equations (ODE) applying meaningful boundary conditions.In order to obtain the non-linear ODEs analytically,Galerkin method (GM) is employed.Subsequently,the ODEs are also solved by a reliable numerical solution.In order to test the accuracy,precision and reliability of the analytical method,results of the analytical analysis are compared with the numerical results.With respect to the comparisons,fairly good compatibilities with insignificant errors are observed.Eventually,the impacts of effective parameters including magnetic and radiation parameters and nanofluid volume fraction on the velocity,skin friction coefficient and Nusselt number distributions are comprehensively described.Based on the results,it is revealed that with increasing the role of magnetic force,velocity profile,skin friction coefficient and thermal performance descend.Radiation parameter has insignificant influence on velocity profile while it obviously has augmentative and decreasing effects on skin friction and Nusselt number,respectively.展开更多
Presence of different terms with various values can alter the thermal behavior of the nanofluids flow over porous surfaces.The aim of this research is to study the influence of nanoparticles volume fraction,nanopartic...Presence of different terms with various values can alter the thermal behavior of the nanofluids flow over porous surfaces.The aim of this research is to study the influence of nanoparticles volume fraction,nanoparticles type,suction or injection,the heat generation or absorption,the Eckert number,thermal and velocity slip parameters,and radiation on the velocity and temperature fields on the flow and heat transfer over a porous flat plate.Four different types of nanoparticles including metal nanoparticles (Cu),metal oxide nanoparticles (Al2O3) and carbon-based nanomaterials (MWCNTs and SWCNTs) which were dispersed in the water (as based fluid) are studied.The governing equations are converted into the ordinary differential equations using similarity solution and solved numerically by the RKF45 algorithm.The results of the simulations showed a contradiction with the results of other researchers who expressed that using nanoparticles with higher thermal conductivity and volume fraction led to increasing heat transfer rate in nanofluids;this study proves that,in some cases,boosting the volume fraction of nanoparticles has a potential to decrease the heat transfer rate due to significant changes in values of some parameters including radiation,heat generation,and viscous dissipation.展开更多
Due to global energy depletion,solar energy technology has been widely used in the world.The output power of the solar energy systems is affected by solar radiation.Accurate short-term forecasting of solar radiation c...Due to global energy depletion,solar energy technology has been widely used in the world.The output power of the solar energy systems is affected by solar radiation.Accurate short-term forecasting of solar radiation can ensure the safety of photovoltaic grids and improve the utilization efficiency of the solar energy systems.In the study,a new decomposition-boosting model using artificial intelligence is proposed to realize the solar radiation multi-step prediction.The proposed model includes four parts:signal decomposition(EWT),neural network(NARX),Adaboost and ARIMA.Three real solar radiation datasets from Changde,China were used to validate the efficiency of the proposed model.To verify the robustness of the multi-step prediction model,this experiment compared nine models and made 1,3,and 5 steps ahead predictions for the time series.It is verified that the proposed model has the best performance among all models.展开更多
The aim of this paper is to achieve the radio frequency stealth(RFS) during the course of tracking by controlling the radiation energy and the interval of a radar. Firstly, we build the model of probability of interce...The aim of this paper is to achieve the radio frequency stealth(RFS) during the course of tracking by controlling the radiation energy and the interval of a radar. Firstly, we build the model of probability of interception with the once radiation during the course of tracking. Secondly, we establish the model of the cumulative probability of interception to describe the effect of RFS throughout the tracking process and obtain two solutions that are minimizing the probability of interception and the radiation times to reduce the cumulative probability of interception. Thirdly, we propose a self-adapting radiation energy control method(SARE)to minimize the probability of interception. Fourthly, we propose a self-adapting radiation interval control method(SARI) to minimize radiation times. Fifthly, combining SARE with SARI, we propose a SARE-SARI control method(SAEI) during the course of tracking.Finally, we compare SAEI with two others by simulation, and the results show the effect of RFS of SAEI is better than the other two,but we have to make a trade-off between the ability of RFS and the effect of tracking.展开更多
A grating-resonator composite structure was investigated.The output characteristics of Smith-Purcell radiation in this grating-resonator composite structure were studied by optical theoretic analysis and particle-in-c...A grating-resonator composite structure was investigated.The output characteristics of Smith-Purcell radiation in this grating-resonator composite structure were studied by optical theoretic analysis and particle-in-cell simulation method.The results showthat tunable coherent Smith-Purcell radiation at Terahertz wavelengths can be generated by this novel structure.This novel grating-resonator composite structure has the following advantages:it can reflect all radiation with an emission angle and random azimuthal angles which backs onto the electron beam with same phase and cause the electrons to be modulated.展开更多
Background and objectives:The incidence of symptomatic radiation pneumonitis(RP)and its relationship with dose-volume histogram(DVH)parameters in non-small cell lung cancer(NSCLC)patients receiving epidermal growth fa...Background and objectives:The incidence of symptomatic radiation pneumonitis(RP)and its relationship with dose-volume histogram(DVH)parameters in non-small cell lung cancer(NSCLC)patients receiving epidermal growth factor receptortyrosine kinase inhibitors(EGFR-TKIs)and concurrent once-daily thoracic radiotherapy(TRT)remain unclear.We aim to analyze the values of clinical factors and dose-volume histogram(DVH)parameters to predict the risk for symptomatic RP in these patients.Methods:Between 2011 and 2019,we retrospectively analyzed and identified 85 patients who had received EGFR-TKIs and oncedaily TRT simultaneously(EGFR-TKIs group)and 129 patients who had received concurrent chemoradiotherapy(CCRT group).The symptomatic RP was recorded according to the Common Terminology Criteria for Adverse Event(CTCAE)criteria(grade 2 or above).Statistical analyses were performed using SPSS 26.0.Results:In total,the incidences of symptomatic(grade≥2)and severe RP(grade≥3)were 43.5%(37/85)and 16.5%(14/85)in EGFR-TKIs group vs 27.1%(35/129)and 10.1%(13/129)in CCRT group respectively.After 1:1 ratio between EGFR-TKIs group and CCRT group was matched by propensity score matching,chi-square test suggested that the incidence of symptomatic RP in the MATCHED EGFR-TKIs group was higher than that in the matched CCRT group(χ^(2)=4.469,P=0.035).In EGFRTKIs group,univariate and multivariate analyses indicated that the percentage of ipsilateral lung volume receiving≥30 Gy(ilV_(30))[odds ratio(OR):1.163,95%CI:1.036-1.306,P=0.011]and the percentage of total lung volume receiving≥20 Gy(tlV_(20))(OR:1.171,95%CI:1.031-1.330,P=0.015),with chronic obstructive pulmonary disease(COPD)or not(OR:0.158,95%CI:0.041-0.600,P=0.007),were independent predictors of symptomatic RP.Compared to patients with lower iIV_(30)/tlV_(20)values(ilV_(30)and tlV_(20)<cut-off point values)and without COPD,patients with higher ilV_(30)/tlV_(20)values(ilV_(30)and tlV_(20)>cut-off point values)and COPD had a significantly higher risk for developing symptomatic RP,with a hazard ratio(HR)of 1.350(95%CI:1.190-1.531,P<0.001).Conclusion:Patients receiving both EGFR-TKIs and once-daily TRT were more likely to develop symptomatic RP than patients receiving concurrent chemoradiotherapy.The ilV_(30),tlV_(20),and comorbidity of COPD may predict the risk of symptomatic RP among NSCLC patients receiving EGFR-TKIs and conventionally fractionated TRT concurrently.展开更多
In this study,a series of hypervelocity impact tests were carried out based on a two-stage light gas gun,and the sequence spectrum and radiation evolution data of the impact products under different impact conditions ...In this study,a series of hypervelocity impact tests were carried out based on a two-stage light gas gun,and the sequence spectrum and radiation evolution data of the impact products under different impact conditions were obtained.The diameter of the projectile is 3-5 mm,the impact velocity is 3.13-6.58 km/s,and the chamber pressure is 0.56-990 Pa.The spectrum of ejected debris cloud in the 250-310 nm band were obtained using a transient spectral measurement system and a multi-channel radiometer measurement system.The test results reveal that the flash radiation intensity increases as a power function with the kinetic energy of the impact.Furthermore,the peak value of the line spectrum decreases as the chamber vacuum degree increases,while the radiation width gradually expands.The line spectrum in the spectral characterization curve corresponds to the ejected debris clouds splitting phase,which does not produce significant line spectrum during material fragmentation and is dominated by the continuum spectrum produced by blackbody radiation.There will appear one or three characteristic peaks in the flash radiation time curve,the first and second peaks correspond to the penetration phase and the third peak corresponds to the expansion phase of the ejected debris clouds on the time scale,the first and second peaks are more sensitive to the chamber vacuum degree,and when the pressure is higher than 99 Pa,the first and second characteristic peaks will disappear.The radiant heat attenuation of the flash under different impact conditions is significantly different,the attenuation exponent has a power function relationship with the impact velocity and the chamber vacuum degree,while the attenuation exponent has a linear relationship with the diameter of the projectile,the specific expression of the attenuation exponent is obtained by fitting.The findings from this research can serve as a valuable reference for remote diagnostic technologies based on flash radiation characteristics.展开更多
Based on the thermodynamics theory and physical micro-properties of solid materials subjected to external loading at room temperature,a formula of calculating temperature difference of infrared radiation in terms of t...Based on the thermodynamics theory and physical micro-properties of solid materials subjected to external loading at room temperature,a formula of calculating temperature difference of infrared radiation in terms of the sum of three principal strains was deduced to quantitatively investigate the infrared radiation characteristics in test. Two typical specimens,the three-point bending beam and the disc pressed in diameter,were tested and their principal strains were calculated by finite element method in order to obtain the temperature differences of infrared radiation. Numerical results are in a good agreement with test results,which verifies the validity of the formula of calculating temperature differences of infrared radiation and the model of quantitatively describing the infrared radiation characteristics of solid materials,and reveals the corresponding inner physical mechanism.展开更多
As the fastest integral equation solver to date, the multilevel fast multipole algorithm （MLFMA） has been applied successfully to solve electromagnetic scattering and radiation from 3D electrically large objects. Bu...As the fastest integral equation solver to date, the multilevel fast multipole algorithm （MLFMA） has been applied successfully to solve electromagnetic scattering and radiation from 3D electrically large objects. But for very large-scale problems, the storage and CPU time required in MLFMA are still expensive. Fast 3D electromagnetic scattering and radiation solvers are introduced based on MLFMA. A brief review of MLFMA is first given. Then, four fast methods including higher-order MLFMA （HO-MLFMA）, fast far field approximation combined with adaptive ray propagation MLFMA （FAFFA-ARP-MLFMA）, local MLFMA and parallel MLFMA are introduced. Some typical numerical results demonstrate the efficiency of these fast methods.展开更多
Soybean Dongnong 47 was subjected to the experiments of increasing UV-B radiation and water stress on soybean yield components in different growth periods. The results showed that 100-seed weight greatly increased dur...Soybean Dongnong 47 was subjected to the experiments of increasing UV-B radiation and water stress on soybean yield components in different growth periods. The results showed that 100-seed weight greatly increased during the early stage of pod filling in the treatment of weak UV-B radiation, seed number per plant as well as seed weight per plant and Dongnong47 yield also increased, while the yield and yield components of Dongnong47 during the blossom to mature period were negatively affected in the treatment of intensive UV-B radiation. 100-seed weight of Dongnong47 all increased in the double factor treatments of UV-B radiation and water stress, with the drought intensified, seed number per plant, seed weight per plant and yield of Dongnong47 decreased, the change of 100-seed weight were various and the antagonistic action of UV-B radiation and water stress were related with their intensity.展开更多
Thermophotovoltaic （TPV） system has been regarded as one promising means to alleviate current energy demand because it can directly generate electricity from radiation heat via photons. However, the presently availa...Thermophotovoltaic （TPV） system has been regarded as one promising means to alleviate current energy demand because it can directly generate electricity from radiation heat via photons. However, the presently available TPV systems suffer from low conversion efficiency and low throughput. A viable solution to increase their efficiency is to apply micro/nanoscale radiation principles in the design of different components to utilize the characteristics ~f thermal radiation at small distances and in microstructures. Several critical issues are reviewed, such as photovoltaic effect, quantum efficiency and efficiency of TPV system. Emphasis is given to the development of wavelength-selective emitters and filters and the aspects of micro/nanoscale heat transfer. Recent progress, along with the challenges and opportunities for future development of TPV systems are also outlined.展开更多
This study presents the effect of non-uniform heat source on the magneto-hydrodynamic flow of nanofluid across an expanding plate with consideration of the homogeneous-heterogeneous reactions and thermal radiation eff...This study presents the effect of non-uniform heat source on the magneto-hydrodynamic flow of nanofluid across an expanding plate with consideration of the homogeneous-heterogeneous reactions and thermal radiation effects.A nanofluid’s dynamic viscosity and effective thermal conductivity are specified with Corcione correlation.According to this correlation,the thermal conductivity is carried out by the Brownian motion.Similarity transformations reduce the governing equations concerned with energy,momentum,and concentration of nanofluid and then numerically solved.The influences of the effective parameters,e.g.,the internal heat source parameters,the volume fraction of nanofluid,the radiation parameter,the homogeneous reaction parameter,the magnetic parameter,the heterogeneous parameter and the Schmidt number are studied on the heat and flow transfer features.Further,regarding the effective parameters of the present work,the correlation for the Nusselt number has been developed.The outcomes illustrate that with the raising of the heterogeneous parameter and the homogeneous reaction parameter,the concentration profile diminishes.In addition,the outcomes point to a reverse relationship between the Nusselt number and the internal heat source parameters.展开更多
The annealing time is an important affecting factor in the performance of many furnaces.The present work deals with the transient simulation of annealing process in a cubic furnace in which a solid element is placed i...The annealing time is an important affecting factor in the performance of many furnaces.The present work deals with the transient simulation of annealing process in a cubic furnace in which a solid element is placed in its center.As the working gas can have some radiating features,a set of governing equations including the energy balance with the radiative transfer equation(RTE)for the gray radiating medium and the conduction equation inside the solid product are numerically solved with progressing in time.Numerical results which are validated against both analytical and theoretical findings in the literature demonstrate that during the starting period,a high rate of radiant energy transfers into the solid body even at small optical thickness.This behavior which hastens the rate of heat transfer at low values of the radiation conduction parameter,causes a fast annealing process in which the solid body warms up to its maximum temperature.Moreover,it is revealed that the rate of heat transfer is an increasing function of radiation-conduction parameter.展开更多
A radiation hard phase-locked loop （PLL） is designed at 2.5 GHz using silicon on sapphire complementary metal-oxide-semiconductor process. Radiation hardness is achieved through improving circuit design without sacr...A radiation hard phase-locked loop （PLL） is designed at 2.5 GHz using silicon on sapphire complementary metal-oxide-semiconductor process. Radiation hardness is achieved through improving circuit design without sacrificing real estate. Stability is guaranteed by a fully self-bias architecture. The lock time of PLL is minimized by maximizing the loop bandwidth. Frequency tuning range of voltage controlled oscillator is significantly enhanced by a novel load configuration. In addition, multiple bias stages, asynchronous frequency divider, and silicon on sapphire process jointly make the proposed PLL more radiation hard. Layout of this PLL is simulated by Cadence Spectre RF under both single event effect and total induced dose effect. Simulation results demonstrate excellent stability, lock time 〈 600 ns, frequency tuning range [1.57 GHz, 3.46 GHz], and jitter 〈 12 ps. Through comparison with PLLs in literatures, the PLL is especially superior in terms of lock time and frequency tuning range performances.展开更多
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
Numerical study was performed to evaluate the characteristics of combined heat transfer of radiation, conduction and convection in indirect near infrared ray （N/R） heating chamber. The effects of important design pa...Numerical study was performed to evaluate the characteristics of combined heat transfer of radiation, conduction and convection in indirect near infrared ray （N/R） heating chamber. The effects of important design parameters such as the shape of heat absorbing cylinder and heat releasing fin on the pressure drop and heat transfer coefficient were analyzed with different Reynolds numbers. The Reynolds numbers were varied from 103 to 3x106, which was defined based on the hydraulic diameter of the heat absorbing cylinder. Analyses were performed to obtain the inner and outer flow and the temperature distributions in the heat absorbing cylinder and the rates of radiation heat transfer and convection heat transfer. As the Reynolds number increases, the convection heat transfer rate is increased while the radiation heat transfer rate is decreased. The average convection heat transfer rate follows a power rule of the Reynolds number. Addition of three-dimensional heat releasing fin to the outside of the heat absorbing cylinder enhances the convection heat transfer.展开更多
基金funded by the National Defence University of Malaysia(Grant No.UPNM/2022/GPJP/SG/3)My Brain Sc Scholarship 2023。
文摘This study explores the impact of bismuth oxide(Bi_(2)O_(3))on the optical and radiation shielding properties of transparent,lead-free thulium-doped bismuth borotellurite radiation shielding glass.The investigated glass composition follows the formula[(TeO_(2))_(75)(B_(2)O_(3))_(25)]_(98-x)(Bi_(2)O_(3))_x[Tm_(2)O_(3)]_(2),where x=0 mol%,5 mol%,10 mol%,15 mol%,20 mol%,25 mol%,and 30 mol%.All glass samples remain transparent,with an optical bandgap(E_(opt))exceeding 3.1 e V,ensuring visible light transmission.Radiation shielding data from Phy-X and XCom reveal interactions of the photoelectric effect,Compton scattering,and pair production,with minimal relative difference in mass attenuation coefficient(MAC)which is between0.05 and 0.56.At 0.662 Me V photon energy,the 20 mol%and 25 mol%Bi_(2)O_(3)glasses exhibit significantly higher Phy-X MAC values than other samples,except RS 520 glass,which contains 71%Pb O.Despite incorporating only up to 25 mol%Bi_(2)O_(3),these glasses outperform others in density,half-value layer(HVL),and mean free path(MFP).Correlating E_(opt)and MAC,the 20 mol%Bi_(2)O_(3)glass is the best candidate for transparent radiation shielding glass due to its wide optical bandgap which prevents ionization of trapped holes.Significantly,the linkage between MFP and molar refraction was also discovered based on the particle size influence on both parameters.
基金supported by the National Defense Pre-research Foundation of China(012015012600A2203)。
文摘In decades,the battlefield environment is becoming more and more complex with plenty of electronic equipments.Thus,in order to improve the survivability of radar sensors and satisfy the requirement of maneuvering target tracking with a low probability of intercept,a non-myopic scheduling is proposed to minimize the radiation cost with tracking accuracy constraint.At first,the scheduling problem is formulated as a partially observable Markov decision process(POMDP).Then the tracking accuracy and radiation cost over the future finite time horizon are predicted by the posterior carmer-rao lower bound(PCRLB) and the hidden Markov model filter,respectively.Finally,the proposed scheduling is implemented efficiently by utilizing the branch and bound(B&B) pruning algorithm.Simulation results show that the performance of maneuvering target tracking was improved by the improved interacting multiple model(IMM),and the scheduler time and maximum memory consumption were significant reduced by the present B&B pruning algorithm without losing the optimal solution.
文摘The main goal of this paper is to investigate natural convective heat transfer and flow characteristics of non-Newtonian nanofluid streaming between two infinite vertical flat plates in the presence of magnetic field and thermal radiation.Initially,a similarity transformation is used to convert momentum and energy conservation equations in partial differential forms into non-linear ordinary differential equations (ODE) applying meaningful boundary conditions.In order to obtain the non-linear ODEs analytically,Galerkin method (GM) is employed.Subsequently,the ODEs are also solved by a reliable numerical solution.In order to test the accuracy,precision and reliability of the analytical method,results of the analytical analysis are compared with the numerical results.With respect to the comparisons,fairly good compatibilities with insignificant errors are observed.Eventually,the impacts of effective parameters including magnetic and radiation parameters and nanofluid volume fraction on the velocity,skin friction coefficient and Nusselt number distributions are comprehensively described.Based on the results,it is revealed that with increasing the role of magnetic force,velocity profile,skin friction coefficient and thermal performance descend.Radiation parameter has insignificant influence on velocity profile while it obviously has augmentative and decreasing effects on skin friction and Nusselt number,respectively.
文摘Presence of different terms with various values can alter the thermal behavior of the nanofluids flow over porous surfaces.The aim of this research is to study the influence of nanoparticles volume fraction,nanoparticles type,suction or injection,the heat generation or absorption,the Eckert number,thermal and velocity slip parameters,and radiation on the velocity and temperature fields on the flow and heat transfer over a porous flat plate.Four different types of nanoparticles including metal nanoparticles (Cu),metal oxide nanoparticles (Al2O3) and carbon-based nanomaterials (MWCNTs and SWCNTs) which were dispersed in the water (as based fluid) are studied.The governing equations are converted into the ordinary differential equations using similarity solution and solved numerically by the RKF45 algorithm.The results of the simulations showed a contradiction with the results of other researchers who expressed that using nanoparticles with higher thermal conductivity and volume fraction led to increasing heat transfer rate in nanofluids;this study proves that,in some cases,boosting the volume fraction of nanoparticles has a potential to decrease the heat transfer rate due to significant changes in values of some parameters including radiation,heat generation,and viscous dissipation.
基金Project(2020TJ-Q06)supported by Hunan Provincial Science&Technology Talent Support,ChinaProject(KQ1707017)supported by the Changsha Science&Technology,ChinaProject(2019CX005)supported by the Innovation Driven Project of the Central South University,China。
文摘Due to global energy depletion,solar energy technology has been widely used in the world.The output power of the solar energy systems is affected by solar radiation.Accurate short-term forecasting of solar radiation can ensure the safety of photovoltaic grids and improve the utilization efficiency of the solar energy systems.In the study,a new decomposition-boosting model using artificial intelligence is proposed to realize the solar radiation multi-step prediction.The proposed model includes four parts:signal decomposition(EWT),neural network(NARX),Adaboost and ARIMA.Three real solar radiation datasets from Changde,China were used to validate the efficiency of the proposed model.To verify the robustness of the multi-step prediction model,this experiment compared nine models and made 1,3,and 5 steps ahead predictions for the time series.It is verified that the proposed model has the best performance among all models.
基金supported by the National Natural Science Foundation of China(61472441)
文摘The aim of this paper is to achieve the radio frequency stealth(RFS) during the course of tracking by controlling the radiation energy and the interval of a radar. Firstly, we build the model of probability of interception with the once radiation during the course of tracking. Secondly, we establish the model of the cumulative probability of interception to describe the effect of RFS throughout the tracking process and obtain two solutions that are minimizing the probability of interception and the radiation times to reduce the cumulative probability of interception. Thirdly, we propose a self-adapting radiation energy control method(SARE)to minimize the probability of interception. Fourthly, we propose a self-adapting radiation interval control method(SARI) to minimize radiation times. Fifthly, combining SARE with SARI, we propose a SARE-SARI control method(SAEI) during the course of tracking.Finally, we compare SAEI with two others by simulation, and the results show the effect of RFS of SAEI is better than the other two,but we have to make a trade-off between the ability of RFS and the effect of tracking.
基金Supported by National Natural Science of China(11275089,11375081)
文摘A grating-resonator composite structure was investigated.The output characteristics of Smith-Purcell radiation in this grating-resonator composite structure were studied by optical theoretic analysis and particle-in-cell simulation method.The results showthat tunable coherent Smith-Purcell radiation at Terahertz wavelengths can be generated by this novel structure.This novel grating-resonator composite structure has the following advantages:it can reflect all radiation with an emission angle and random azimuthal angles which backs onto the electron beam with same phase and cause the electrons to be modulated.
文摘Background and objectives:The incidence of symptomatic radiation pneumonitis(RP)and its relationship with dose-volume histogram(DVH)parameters in non-small cell lung cancer(NSCLC)patients receiving epidermal growth factor receptortyrosine kinase inhibitors(EGFR-TKIs)and concurrent once-daily thoracic radiotherapy(TRT)remain unclear.We aim to analyze the values of clinical factors and dose-volume histogram(DVH)parameters to predict the risk for symptomatic RP in these patients.Methods:Between 2011 and 2019,we retrospectively analyzed and identified 85 patients who had received EGFR-TKIs and oncedaily TRT simultaneously(EGFR-TKIs group)and 129 patients who had received concurrent chemoradiotherapy(CCRT group).The symptomatic RP was recorded according to the Common Terminology Criteria for Adverse Event(CTCAE)criteria(grade 2 or above).Statistical analyses were performed using SPSS 26.0.Results:In total,the incidences of symptomatic(grade≥2)and severe RP(grade≥3)were 43.5%(37/85)and 16.5%(14/85)in EGFR-TKIs group vs 27.1%(35/129)and 10.1%(13/129)in CCRT group respectively.After 1:1 ratio between EGFR-TKIs group and CCRT group was matched by propensity score matching,chi-square test suggested that the incidence of symptomatic RP in the MATCHED EGFR-TKIs group was higher than that in the matched CCRT group(χ^(2)=4.469,P=0.035).In EGFRTKIs group,univariate and multivariate analyses indicated that the percentage of ipsilateral lung volume receiving≥30 Gy(ilV_(30))[odds ratio(OR):1.163,95%CI:1.036-1.306,P=0.011]and the percentage of total lung volume receiving≥20 Gy(tlV_(20))(OR:1.171,95%CI:1.031-1.330,P=0.015),with chronic obstructive pulmonary disease(COPD)or not(OR:0.158,95%CI:0.041-0.600,P=0.007),were independent predictors of symptomatic RP.Compared to patients with lower iIV_(30)/tlV_(20)values(ilV_(30)and tlV_(20)<cut-off point values)and without COPD,patients with higher ilV_(30)/tlV_(20)values(ilV_(30)and tlV_(20)>cut-off point values)and COPD had a significantly higher risk for developing symptomatic RP,with a hazard ratio(HR)of 1.350(95%CI:1.190-1.531,P<0.001).Conclusion:Patients receiving both EGFR-TKIs and once-daily TRT were more likely to develop symptomatic RP than patients receiving concurrent chemoradiotherapy.The ilV_(30),tlV_(20),and comorbidity of COPD may predict the risk of symptomatic RP among NSCLC patients receiving EGFR-TKIs and conventionally fractionated TRT concurrently.
基金supported by the National Natural Science Foundation of China (Grant No.11672278)。
文摘In this study,a series of hypervelocity impact tests were carried out based on a two-stage light gas gun,and the sequence spectrum and radiation evolution data of the impact products under different impact conditions were obtained.The diameter of the projectile is 3-5 mm,the impact velocity is 3.13-6.58 km/s,and the chamber pressure is 0.56-990 Pa.The spectrum of ejected debris cloud in the 250-310 nm band were obtained using a transient spectral measurement system and a multi-channel radiometer measurement system.The test results reveal that the flash radiation intensity increases as a power function with the kinetic energy of the impact.Furthermore,the peak value of the line spectrum decreases as the chamber vacuum degree increases,while the radiation width gradually expands.The line spectrum in the spectral characterization curve corresponds to the ejected debris clouds splitting phase,which does not produce significant line spectrum during material fragmentation and is dominated by the continuum spectrum produced by blackbody radiation.There will appear one or three characteristic peaks in the flash radiation time curve,the first and second peaks correspond to the penetration phase and the third peak corresponds to the expansion phase of the ejected debris clouds on the time scale,the first and second peaks are more sensitive to the chamber vacuum degree,and when the pressure is higher than 99 Pa,the first and second characteristic peaks will disappear.The radiant heat attenuation of the flash under different impact conditions is significantly different,the attenuation exponent has a power function relationship with the impact velocity and the chamber vacuum degree,while the attenuation exponent has a linear relationship with the diameter of the projectile,the specific expression of the attenuation exponent is obtained by fitting.The findings from this research can serve as a valuable reference for remote diagnostic technologies based on flash radiation characteristics.
基金Projects (10775018, 10702010, 50374073) supported by the National Natural Science Foundation of ChinaProject(2002CB412701) supported by the National Basic Research Program of China
文摘Based on the thermodynamics theory and physical micro-properties of solid materials subjected to external loading at room temperature,a formula of calculating temperature difference of infrared radiation in terms of the sum of three principal strains was deduced to quantitatively investigate the infrared radiation characteristics in test. Two typical specimens,the three-point bending beam and the disc pressed in diameter,were tested and their principal strains were calculated by finite element method in order to obtain the temperature differences of infrared radiation. Numerical results are in a good agreement with test results,which verifies the validity of the formula of calculating temperature differences of infrared radiation and the model of quantitatively describing the infrared radiation characteristics of solid materials,and reveals the corresponding inner physical mechanism.
基金the National Natural Science Foundation of China (60431010, 60601008)the New CenturyExcellent Talent Support Plan of China (NCET-05-0805)+2 种基金the International Joint Research Project ("111" Project)(b07048)the"973" Programs 61360(2008CB317110)Young Doctor Displine Platform University of Electronic Science and Technology of China.
文摘As the fastest integral equation solver to date, the multilevel fast multipole algorithm （MLFMA） has been applied successfully to solve electromagnetic scattering and radiation from 3D electrically large objects. But for very large-scale problems, the storage and CPU time required in MLFMA are still expensive. Fast 3D electromagnetic scattering and radiation solvers are introduced based on MLFMA. A brief review of MLFMA is first given. Then, four fast methods including higher-order MLFMA （HO-MLFMA）, fast far field approximation combined with adaptive ray propagation MLFMA （FAFFA-ARP-MLFMA）, local MLFMA and parallel MLFMA are introduced. Some typical numerical results demonstrate the efficiency of these fast methods.
基金Supported by Postdoctoral Fund of Settling Down in Heilongjiang Province (LBH-Z05086)Scientific Research Fund of Northeast Agricultural University
文摘Soybean Dongnong 47 was subjected to the experiments of increasing UV-B radiation and water stress on soybean yield components in different growth periods. The results showed that 100-seed weight greatly increased during the early stage of pod filling in the treatment of weak UV-B radiation, seed number per plant as well as seed weight per plant and Dongnong47 yield also increased, while the yield and yield components of Dongnong47 during the blossom to mature period were negatively affected in the treatment of intensive UV-B radiation. 100-seed weight of Dongnong47 all increased in the double factor treatments of UV-B radiation and water stress, with the drought intensified, seed number per plant, seed weight per plant and yield of Dongnong47 decreased, the change of 100-seed weight were various and the antagonistic action of UV-B radiation and water stress were related with their intensity.
基金Project(2009AA05Z215) supported by the National High Technology Research and Development Program of China
文摘Thermophotovoltaic （TPV） system has been regarded as one promising means to alleviate current energy demand because it can directly generate electricity from radiation heat via photons. However, the presently available TPV systems suffer from low conversion efficiency and low throughput. A viable solution to increase their efficiency is to apply micro/nanoscale radiation principles in the design of different components to utilize the characteristics ~f thermal radiation at small distances and in microstructures. Several critical issues are reviewed, such as photovoltaic effect, quantum efficiency and efficiency of TPV system. Emphasis is given to the development of wavelength-selective emitters and filters and the aspects of micro/nanoscale heat transfer. Recent progress, along with the challenges and opportunities for future development of TPV systems are also outlined.
文摘This study presents the effect of non-uniform heat source on the magneto-hydrodynamic flow of nanofluid across an expanding plate with consideration of the homogeneous-heterogeneous reactions and thermal radiation effects.A nanofluid’s dynamic viscosity and effective thermal conductivity are specified with Corcione correlation.According to this correlation,the thermal conductivity is carried out by the Brownian motion.Similarity transformations reduce the governing equations concerned with energy,momentum,and concentration of nanofluid and then numerically solved.The influences of the effective parameters,e.g.,the internal heat source parameters,the volume fraction of nanofluid,the radiation parameter,the homogeneous reaction parameter,the magnetic parameter,the heterogeneous parameter and the Schmidt number are studied on the heat and flow transfer features.Further,regarding the effective parameters of the present work,the correlation for the Nusselt number has been developed.The outcomes illustrate that with the raising of the heterogeneous parameter and the homogeneous reaction parameter,the concentration profile diminishes.In addition,the outcomes point to a reverse relationship between the Nusselt number and the internal heat source parameters.
文摘The annealing time is an important affecting factor in the performance of many furnaces.The present work deals with the transient simulation of annealing process in a cubic furnace in which a solid element is placed in its center.As the working gas can have some radiating features,a set of governing equations including the energy balance with the radiative transfer equation(RTE)for the gray radiating medium and the conduction equation inside the solid product are numerically solved with progressing in time.Numerical results which are validated against both analytical and theoretical findings in the literature demonstrate that during the starting period,a high rate of radiant energy transfers into the solid body even at small optical thickness.This behavior which hastens the rate of heat transfer at low values of the radiation conduction parameter,causes a fast annealing process in which the solid body warms up to its maximum temperature.Moreover,it is revealed that the rate of heat transfer is an increasing function of radiation-conduction parameter.
文摘A radiation hard phase-locked loop （PLL） is designed at 2.5 GHz using silicon on sapphire complementary metal-oxide-semiconductor process. Radiation hardness is achieved through improving circuit design without sacrificing real estate. Stability is guaranteed by a fully self-bias architecture. The lock time of PLL is minimized by maximizing the loop bandwidth. Frequency tuning range of voltage controlled oscillator is significantly enhanced by a novel load configuration. In addition, multiple bias stages, asynchronous frequency divider, and silicon on sapphire process jointly make the proposed PLL more radiation hard. Layout of this PLL is simulated by Cadence Spectre RF under both single event effect and total induced dose effect. Simulation results demonstrate excellent stability, lock time 〈 600 ns, frequency tuning range [1.57 GHz, 3.46 GHz], and jitter 〈 12 ps. Through comparison with PLLs in literatures, the PLL is especially superior in terms of lock time and frequency tuning range performances.
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 Second Stage of Brain Korea 21 Projects
文摘Numerical study was performed to evaluate the characteristics of combined heat transfer of radiation, conduction and convection in indirect near infrared ray （N/R） heating chamber. The effects of important design parameters such as the shape of heat absorbing cylinder and heat releasing fin on the pressure drop and heat transfer coefficient were analyzed with different Reynolds numbers. The Reynolds numbers were varied from 103 to 3x106, which was defined based on the hydraulic diameter of the heat absorbing cylinder. Analyses were performed to obtain the inner and outer flow and the temperature distributions in the heat absorbing cylinder and the rates of radiation heat transfer and convection heat transfer. As the Reynolds number increases, the convection heat transfer rate is increased while the radiation heat transfer rate is decreased. The average convection heat transfer rate follows a power rule of the Reynolds number. Addition of three-dimensional heat releasing fin to the outside of the heat absorbing cylinder enhances the convection heat transfer.
