Non-cylindrical casings filled with explosives have undergone rapid development in warhead design and explosion control.The fragment spatial distribution of prismatic casings is more complex than that of traditional c...Non-cylindrical casings filled with explosives have undergone rapid development in warhead design and explosion control.The fragment spatial distribution of prismatic casings is more complex than that of traditional cylindrical casings.In this study,numerical and experimental investigations into the fragment spatial distribution of a prismatic casing were conducted.A new numerical method,which adds the Lagrangian marker points to the Eulerian grid,was proposed to track the multi-material interfaces and material dynamic fractures.Physical quantity mappings between the Lagrangian marker points and Eulerian grid were achieved by their topological relationship.Thereafter,the fragment spatial distributions of the prismatic casing with different fragment sizes,fragment shapes,and casing geometries were obtained using the numerical method.Moreover,fragment spatial distribution experiments were conducted on the prismatic casing with different fragment sizes and shapes,and the experimental data were compared with the numerical results.The effects of the fragment and casing geometry on the fragment spatial distributions were determined by analyzing the numerical results and experimental data.Finally,a formula including the casing geometry parameters was fitted to predict the fragment spatial distribution of the prismatic casing under internal explosive loading.展开更多
A technique based on the double Fourier series is developed to estimate the winds at different isobaric levels forthe limited area domain, 35°E to 140°E and 30°S to 40°N, using the observed winds a...A technique based on the double Fourier series is developed to estimate the winds at different isobaric levels forthe limited area domain, 35°E to 140°E and 30°S to 40°N, using the observed winds at 850 hPa lcvcl for the month ofJune. For this purpose the wind field at a level under consideration is taken in the ratio form with that of 850 hPa level and the coefficients of the double Fouricr series are computed. These coefficients are subsequently used to computethe winds which are compared with the actual winds. The results of the double Fourier series technique are comparedwith those of the polynomial surface fitting method developed by Bavadekar and Khaladkar (1 992). The technique isalso applied for the daily wind data of 11. June, 1979 and the validation of the technique is tested for a few radiosondestations of india. The computed winds for these radiosonde stations arc quite close to observed winds.展开更多
Bifacial PV modules have unique advantages in low-carbon building applications such as BIPV systems but often suffer from the shading problem resulting from higher surrounding objects or building facades.Point-blank q...Bifacial PV modules have unique advantages in low-carbon building applications such as BIPV systems but often suffer from the shading problem resulting from higher surrounding objects or building facades.Point-blank quantitative studies of PV performance of bifacial modules operating in actual environments as affected by shading on PV cells are lacking due to the difficulties of analysis caused by the existing multiple variable factors.By constructing an experimental comparison system on a flat roof of a building,we experimentally tested and analyzed the comparative variation characteristics of PV performance of bifacial and mono-facial modules under different shading area fractions.The results show that from the viewpoint of photoelectric efficiency,the PV performance of both bifacial and mono-facial PV modules clearly varied with the shading fraction of PV cell in some linear rules,though it is difficult to find regularity from the perspective of output power which was also affected by dynamic solar radiation intensity.An abnormal phenomenon emerged that the photoelectric efficiencies of the bifacial modules with small shading fraction were higher compared to the case without shading.Based on the findings of the experimental results,a regression approximation method based on shading test results(RAST Method)is further proposed to analyze and calculate the bifacial gain of bifacial modules.In the case of the existing roof installation,the mean bifacial gains of the two bifacial modules with different inclination angles were 8.86%and 11.30%,respectively.展开更多
Cavity-coupled plasmonic structure is demonstrated to be a simple and effective tool to manipulatelight,enhance the biosensing figure of merit, and control the polarization state. In this Letter, we demonstrate the tu...Cavity-coupled plasmonic structure is demonstrated to be a simple and effective tool to manipulatelight,enhance the biosensing figure of merit, and control the polarization state. In this Letter, we demonstrate the tunability of the chiroptical effect of cavity-coupled chiral structure, i.e., sandwich chiral metamaterials(SCMs), in whichradiation coupling dominates the interaction between particles. Two types of SCMs whose building blocks are 3D chiral and 2D chiral, respectively, are numerically studied. Distinct responses are observed in these two materials. The chiroptical effect can be effectively manipulated and enhanced in the 2D case, while the SCMs consisting of 3D chiral layers keep the chiroptical effecta constant. A theoretical analysis based on matrix optics is developed to explain the corresponding phenomena, which gives a reasonable agreement with numerical simulations.展开更多
The stochastic resonance based on optical bistability in the semiconductor optical amplifier is numerically investigated to extract a weak pulse signal buried in noise. The output property of optical bistability under...The stochastic resonance based on optical bistability in the semiconductor optical amplifier is numerically investigated to extract a weak pulse signal buried in noise. The output property of optical bistability under different system parameters is analyzed, which determines the performance of the stochastic resonance. Through optimizing these parameters, the noise-hidden signal is extracted via stochastic resonance, in which the maximum cross-correlation gain higher than nine is obtained. This provides a novel technology for detecting a weak optical signal in various signal processing fields.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.11822203and 11702026)。
文摘Non-cylindrical casings filled with explosives have undergone rapid development in warhead design and explosion control.The fragment spatial distribution of prismatic casings is more complex than that of traditional cylindrical casings.In this study,numerical and experimental investigations into the fragment spatial distribution of a prismatic casing were conducted.A new numerical method,which adds the Lagrangian marker points to the Eulerian grid,was proposed to track the multi-material interfaces and material dynamic fractures.Physical quantity mappings between the Lagrangian marker points and Eulerian grid were achieved by their topological relationship.Thereafter,the fragment spatial distributions of the prismatic casing with different fragment sizes,fragment shapes,and casing geometries were obtained using the numerical method.Moreover,fragment spatial distribution experiments were conducted on the prismatic casing with different fragment sizes and shapes,and the experimental data were compared with the numerical results.The effects of the fragment and casing geometry on the fragment spatial distributions were determined by analyzing the numerical results and experimental data.Finally,a formula including the casing geometry parameters was fitted to predict the fragment spatial distribution of the prismatic casing under internal explosive loading.
文摘A technique based on the double Fourier series is developed to estimate the winds at different isobaric levels forthe limited area domain, 35°E to 140°E and 30°S to 40°N, using the observed winds at 850 hPa lcvcl for the month ofJune. For this purpose the wind field at a level under consideration is taken in the ratio form with that of 850 hPa level and the coefficients of the double Fouricr series are computed. These coefficients are subsequently used to computethe winds which are compared with the actual winds. The results of the double Fourier series technique are comparedwith those of the polynomial surface fitting method developed by Bavadekar and Khaladkar (1 992). The technique isalso applied for the daily wind data of 11. June, 1979 and the validation of the technique is tested for a few radiosondestations of india. The computed winds for these radiosonde stations arc quite close to observed winds.
基金the National Natural Science Foundation of China(NSFC)(No.51408278)the Jiangxi Provincial Key Research and Development Program,China(No.20202BBEL53033)the Nature Science Foundation of Fujian Province(No.2022J01233269).
文摘Bifacial PV modules have unique advantages in low-carbon building applications such as BIPV systems but often suffer from the shading problem resulting from higher surrounding objects or building facades.Point-blank quantitative studies of PV performance of bifacial modules operating in actual environments as affected by shading on PV cells are lacking due to the difficulties of analysis caused by the existing multiple variable factors.By constructing an experimental comparison system on a flat roof of a building,we experimentally tested and analyzed the comparative variation characteristics of PV performance of bifacial and mono-facial modules under different shading area fractions.The results show that from the viewpoint of photoelectric efficiency,the PV performance of both bifacial and mono-facial PV modules clearly varied with the shading fraction of PV cell in some linear rules,though it is difficult to find regularity from the perspective of output power which was also affected by dynamic solar radiation intensity.An abnormal phenomenon emerged that the photoelectric efficiencies of the bifacial modules with small shading fraction were higher compared to the case without shading.Based on the findings of the experimental results,a regression approximation method based on shading test results(RAST Method)is further proposed to analyze and calculate the bifacial gain of bifacial modules.In the case of the existing roof installation,the mean bifacial gains of the two bifacial modules with different inclination angles were 8.86%and 11.30%,respectively.
基金supported by the National Natural Science Foundation of China under Grant No.61377054
文摘Cavity-coupled plasmonic structure is demonstrated to be a simple and effective tool to manipulatelight,enhance the biosensing figure of merit, and control the polarization state. In this Letter, we demonstrate the tunability of the chiroptical effect of cavity-coupled chiral structure, i.e., sandwich chiral metamaterials(SCMs), in whichradiation coupling dominates the interaction between particles. Two types of SCMs whose building blocks are 3D chiral and 2D chiral, respectively, are numerically studied. Distinct responses are observed in these two materials. The chiroptical effect can be effectively manipulated and enhanced in the 2D case, while the SCMs consisting of 3D chiral layers keep the chiroptical effecta constant. A theoretical analysis based on matrix optics is developed to explain the corresponding phenomena, which gives a reasonable agreement with numerical simulations.
基金supported by the National Natural Science Foundation of China under Grant No.61275134
文摘The stochastic resonance based on optical bistability in the semiconductor optical amplifier is numerically investigated to extract a weak pulse signal buried in noise. The output property of optical bistability under different system parameters is analyzed, which determines the performance of the stochastic resonance. Through optimizing these parameters, the noise-hidden signal is extracted via stochastic resonance, in which the maximum cross-correlation gain higher than nine is obtained. This provides a novel technology for detecting a weak optical signal in various signal processing fields.