A new method is proposed for calculating the aircraft equivalent single vulnerable area using Monte-Carlo simulation technique. The method simulates the kill events of single vulnerable components and multiply vulnera...A new method is proposed for calculating the aircraft equivalent single vulnerable area using Monte-Carlo simulation technique. The method simulates the kill events of single vulnerable components and multiply vulnerable components or redundant components to ＇Model of Filling Boxes with Balls＇, in which the area of each box is equal to the component＇s vulnerable area. By randomly and uniformly sampling the threat hit locations, the expected number of hits required to kill an aircraft can be given and the aircraft equivalent singly vulnerable area can be attained. Examples demonstrate the correctness and feasibility of the proposed method. Analysis show that the developed method overcomes two shortcomings of currently used methods. （1） It can calculate the equivalent single vulnerable area of aircraft with several sets of multiply vulnerable components, and （2） When the components of each multiple set have different vulnerable areas, the method also applies.展开更多
An experiment was conducted during Kharif seasons of 2009 and 2010 on sandy loam soil of West Bengal, India to evaluate the productivity and economic viability of maize ＋ legume intercropping systems in additive as w...An experiment was conducted during Kharif seasons of 2009 and 2010 on sandy loam soil of West Bengal, India to evaluate the productivity and economic viability of maize ＋ legume intercropping systems in additive as well as in replacement series with different row proportions. Maize （Zea rnays L.） cv. ＂Vijay＂ （composite）, green gram （Vigna radiata L.） cv. ＂Samrat＂, black gram （Vigna mungo L.） cv. ＂Sarada＂, soybean （Glycine max L. Merril） cv. ＂PK 327＂ and peanut （Arachis hypogaea L.） cv. ＂JL 24＂, were tested in monoculture as well as in intercropping situations with 1：1 （additive series） and 1：2 ratios （replacement series）. The result indicated that intercropped legumes improved the yield components of maize and offered some bonus yield. The highest maize grain yield （2,916.28 kg/ha） and maize equivalent yield （4,831.45 kg/ha） were recorded with maize ＋ green gram （1：1） and maize ＋ peanut （1：I）, respectively. The values of all the competition functions were always greater than unity and maize ＋ black gram （1：2） recorded the highest values of land equivalent ratio （1.433）, area time equivalent ratio （1.374） and land equivalent coefficient （0.421）. Maximum monetary advantage （Rs. 10,579.13） was found with maize ＋ green gam （l：1）. Maize ＋ peanut （1：2） combination recorded the highest relative net return （2.01）, net return （Rs. 28,523.08）, benefit-cost ratio （2.76） ad per day return （Rs. 259.30）.展开更多
The particle size and shape measured by image analysis is helpful to discuss the human health effects of particulate beside the aerodynamic scale. To explore the size and shape features of particle suspended in the ro...The particle size and shape measured by image analysis is helpful to discuss the human health effects of particulate beside the aerodynamic scale. To explore the size and shape features of particle suspended in the road environment, this research selected 12 bus stations as the sampling sites along the main road in the air polluted city Shijiazhuang, China, where a Car-Free Campaign had been carried out. We hung 2 slides covered with a layer of petroleum jelly to collect suspending particles for 24 hours at each sampling site, and measured the particles size and shape parameters with the Particle Size Analyzer of CIS-50. The results show that the average particle size by the equivalent area diameter is around 10 μm, the size distributions are multi-modal with wide span, demonstrating that coarse dust suspended on road derived from several particle sources. Most of the particles suspended are square or square-like in shape with rugged border. Compared the samples of ordinary days and of the Car-Free day, the size and shape features vary little, inferring the ineffective results for the particle control of the Campaign. There is certain relationship between particle size and shape. The number percent of PMs-E （particulate matter with equivalent area diameter beneath 5 pro） is positively correlative with the number percent of particles of square or square-like shape, and negatively correlative with that of round or round-like shape. This relationship pattern in the road environment is contrary to the situations in the upper atmosphere, inferring different transportation and source emission mechanism influences.展开更多
The problems in calculating parameters of equivalent collection area,earth resistivity and lightning protection category as well as their effects on lightning disaster risk assessment were analyzed,and practical examp...The problems in calculating parameters of equivalent collection area,earth resistivity and lightning protection category as well as their effects on lightning disaster risk assessment were analyzed,and practical examples proved the effects of those differences on lightning protection identification,intercept efficiency calculation in evaluating lightning disaster risk. In the meantime,several new concepts,such as the height of buildings for lightning protection were defined,and a fixed radius value was set to the ground flash density for calculation,establishing the ground flash density formula to solve the problems in parameter calculation,which would be beneficial to promote the standardization of lightning disaster risk assessment.展开更多
Mitigating the sonic boom to an acceptable stage is crucial for the next generation of supersonic transports.The primary way to suppress sonic booms is to develop a low sonic boom aerodynamic shape design.This paper p...Mitigating the sonic boom to an acceptable stage is crucial for the next generation of supersonic transports.The primary way to suppress sonic booms is to develop a low sonic boom aerodynamic shape design.This paper proposes an inverse design approach to optimize the near-field signature of an aircraft,making it close to the shaped ideal ground signature after propagation in the atmosphere.By introducing the Deep Neural Network(DNN)model for the first time,a predicted input of Augmented Burgers equation is inversely achieved.By the K-fold cross-validation method,the pre-dicted ground signature closest to the target ground signature is obtained.Then,the corresponding equivalent area distribution is calculated using the classical Whitham’s F-function theory from the optimal near-field signature.The inversion method is vali-dated using the classic example of the C608 vehicle provided by the Third Sonic Boom Prediction Workshop(SBPW-3).The results show that the design ground signature is consistent with the target signature.The equivalent area distribution of the design result is smoother than the baseline distribution,and it shrinks significantly in the rear section.Finally,the robustness of this method is verified through the inverse design of sonic boom for the non-physical ground signature target.展开更多
基金National Natural Science Foundation of China (10372082) Aeronautical Science Foundation of China(02B53008) and Doctorate Foun-dation of Northwestern Polytechnical University(CX200301)
文摘A new method is proposed for calculating the aircraft equivalent single vulnerable area using Monte-Carlo simulation technique. The method simulates the kill events of single vulnerable components and multiply vulnerable components or redundant components to ＇Model of Filling Boxes with Balls＇, in which the area of each box is equal to the component＇s vulnerable area. By randomly and uniformly sampling the threat hit locations, the expected number of hits required to kill an aircraft can be given and the aircraft equivalent singly vulnerable area can be attained. Examples demonstrate the correctness and feasibility of the proposed method. Analysis show that the developed method overcomes two shortcomings of currently used methods. （1） It can calculate the equivalent single vulnerable area of aircraft with several sets of multiply vulnerable components, and （2） When the components of each multiple set have different vulnerable areas, the method also applies.
文摘An experiment was conducted during Kharif seasons of 2009 and 2010 on sandy loam soil of West Bengal, India to evaluate the productivity and economic viability of maize ＋ legume intercropping systems in additive as well as in replacement series with different row proportions. Maize （Zea rnays L.） cv. ＂Vijay＂ （composite）, green gram （Vigna radiata L.） cv. ＂Samrat＂, black gram （Vigna mungo L.） cv. ＂Sarada＂, soybean （Glycine max L. Merril） cv. ＂PK 327＂ and peanut （Arachis hypogaea L.） cv. ＂JL 24＂, were tested in monoculture as well as in intercropping situations with 1：1 （additive series） and 1：2 ratios （replacement series）. The result indicated that intercropped legumes improved the yield components of maize and offered some bonus yield. The highest maize grain yield （2,916.28 kg/ha） and maize equivalent yield （4,831.45 kg/ha） were recorded with maize ＋ green gram （1：1） and maize ＋ peanut （1：I）, respectively. The values of all the competition functions were always greater than unity and maize ＋ black gram （1：2） recorded the highest values of land equivalent ratio （1.433）, area time equivalent ratio （1.374） and land equivalent coefficient （0.421）. Maximum monetary advantage （Rs. 10,579.13） was found with maize ＋ green gam （l：1）. Maize ＋ peanut （1：2） combination recorded the highest relative net return （2.01）, net return （Rs. 28,523.08）, benefit-cost ratio （2.76） ad per day return （Rs. 259.30）.
基金This research was supported by the Nature Science Foundation of Hebei Province （D2005000176） and the Construction Projects of Key Disciplines in University of Hebei Province, China. The authors would like to thank the support of the Environment Monitoring Center of Shijiazhuang city, China.
文摘The particle size and shape measured by image analysis is helpful to discuss the human health effects of particulate beside the aerodynamic scale. To explore the size and shape features of particle suspended in the road environment, this research selected 12 bus stations as the sampling sites along the main road in the air polluted city Shijiazhuang, China, where a Car-Free Campaign had been carried out. We hung 2 slides covered with a layer of petroleum jelly to collect suspending particles for 24 hours at each sampling site, and measured the particles size and shape parameters with the Particle Size Analyzer of CIS-50. The results show that the average particle size by the equivalent area diameter is around 10 μm, the size distributions are multi-modal with wide span, demonstrating that coarse dust suspended on road derived from several particle sources. Most of the particles suspended are square or square-like in shape with rugged border. Compared the samples of ordinary days and of the Car-Free day, the size and shape features vary little, inferring the ineffective results for the particle control of the Campaign. There is certain relationship between particle size and shape. The number percent of PMs-E （particulate matter with equivalent area diameter beneath 5 pro） is positively correlative with the number percent of particles of square or square-like shape, and negatively correlative with that of round or round-like shape. This relationship pattern in the road environment is contrary to the situations in the upper atmosphere, inferring different transportation and source emission mechanism influences.
文摘The problems in calculating parameters of equivalent collection area,earth resistivity and lightning protection category as well as their effects on lightning disaster risk assessment were analyzed,and practical examples proved the effects of those differences on lightning protection identification,intercept efficiency calculation in evaluating lightning disaster risk. In the meantime,several new concepts,such as the height of buildings for lightning protection were defined,and a fixed radius value was set to the ground flash density for calculation,establishing the ground flash density formula to solve the problems in parameter calculation,which would be beneficial to promote the standardization of lightning disaster risk assessment.
基金the National Key Research and Development Program of China(No.2020YFB1709500)Natural Science Basic Research Program of Shaanxi province(No.2021JQ-076)Fundamental Research Funds for the Central Universities.
文摘Mitigating the sonic boom to an acceptable stage is crucial for the next generation of supersonic transports.The primary way to suppress sonic booms is to develop a low sonic boom aerodynamic shape design.This paper proposes an inverse design approach to optimize the near-field signature of an aircraft,making it close to the shaped ideal ground signature after propagation in the atmosphere.By introducing the Deep Neural Network(DNN)model for the first time,a predicted input of Augmented Burgers equation is inversely achieved.By the K-fold cross-validation method,the pre-dicted ground signature closest to the target ground signature is obtained.Then,the corresponding equivalent area distribution is calculated using the classical Whitham’s F-function theory from the optimal near-field signature.The inversion method is vali-dated using the classic example of the C608 vehicle provided by the Third Sonic Boom Prediction Workshop(SBPW-3).The results show that the design ground signature is consistent with the target signature.The equivalent area distribution of the design result is smoother than the baseline distribution,and it shrinks significantly in the rear section.Finally,the robustness of this method is verified through the inverse design of sonic boom for the non-physical ground signature target.
