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Recorded recurrent deep reinforcement learning guidance laws for intercepting endoatmospheric maneuvering missiles
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作者 Xiaoqi Qiu Peng Lai +1 位作者 Changsheng Gao Wuxing Jing 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2024年第1期457-470,共14页
This work proposes a recorded recurrent twin delayed deep deterministic(RRTD3)policy gradient algorithm to solve the challenge of constructing guidance laws for intercepting endoatmospheric maneuvering missiles with u... This work proposes a recorded recurrent twin delayed deep deterministic(RRTD3)policy gradient algorithm to solve the challenge of constructing guidance laws for intercepting endoatmospheric maneuvering missiles with uncertainties and observation noise.The attack-defense engagement scenario is modeled as a partially observable Markov decision process(POMDP).Given the benefits of recurrent neural networks(RNNs)in processing sequence information,an RNN layer is incorporated into the agent’s policy network to alleviate the bottleneck of traditional deep reinforcement learning methods while dealing with POMDPs.The measurements from the interceptor’s seeker during each guidance cycle are combined into one sequence as the input to the policy network since the detection frequency of an interceptor is usually higher than its guidance frequency.During training,the hidden states of the RNN layer in the policy network are recorded to overcome the partially observable problem that this RNN layer causes inside the agent.The training curves show that the proposed RRTD3 successfully enhances data efficiency,training speed,and training stability.The test results confirm the advantages of the RRTD3-based guidance laws over some conventional guidance laws. 展开更多
关键词 Endoatmospheric interception Missile guidance Reinforcement learning Markov decision process Recurrent neural networks
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复杂岩溶高承压水下深埋地铁车站设计及施工方案研究
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作者 袁丛军 《山西建筑》 2025年第2期124-128,共5页
近十多年来,我国城市轨道交通工程大量建设并投入运营,区间地下隧道与地下车站的顺利建设、安全运营均与地下地质条件密切相关。在各种地质条件中,以复杂岩溶及岩溶水对地下工程的影响最为不利,特别是复杂岩溶发育叠加岩溶高承压水条件... 近十多年来,我国城市轨道交通工程大量建设并投入运营,区间地下隧道与地下车站的顺利建设、安全运营均与地下地质条件密切相关。在各种地质条件中,以复杂岩溶及岩溶水对地下工程的影响最为不利,特别是复杂岩溶发育叠加岩溶高承压水条件下修建地下深埋车站工程最为罕见,难度与风险最大。因此有必要对此类地质条件下地下车站设计方案、施工工艺进行深入的研究与总结。研究结论:赋存于隔水层下的灰岩溶洞和溶隙中的地下水,具有明显的承压性与不均一性,在岩性交界面因溶蚀作用显著增强,往往具有承压管道流特征;复杂岩溶及岩溶承压水条件下地下车站设计采用外截内排、分区实施、设置注浆截水帷幕+坑底处理+减压泄水井的综合设计方案可行有效;根据钻孔情况,采取化学注浆可以显著提高支护桩的成桩率;地下深埋车站的选址应当尽量避开岩溶发育条带与碎屑岩的富水与溶蚀发育交界带,以避免受复杂岩溶及高承压水的不利影响大幅增加工程投资;文中所述的设计方案与施工措施,确保了工程的按期顺利建成,取得了较好的技术、经济和社会效益,其成功的工程勘察设计与施工经验可供其他类似工点参考利用。 展开更多
关键词 深埋车站 复杂岩溶 高承压水 外截内排 围护结构
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使用INTERCEPT血液系统制备血浆的临床前安全试验
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作者 叶兵 《国外医学(输血及血液学分册)》 2004年第3期285-285,共1页
背景和目的 最近发展的血浆INTERCEPT血液系统,通过添加新的补骨脂素,amotosalen HCl(AMOTOSALEN),然后用A段紫外线照射,来灭活可能造成新鲜冻干血浆污染的病毒、细菌、原生物和白细胞。
关键词 intercept 血液系统 制备 血浆 安全试验
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常规血库制品程序中血小板INTERCEPT血液系统的应用:单采血小板的评价
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作者 叶兵 《国外医学(输血及血液学分册)》 2004年第5期475-475,共1页
关键词 常规血库制品程序 血小板 intercept血液系统 单采血小板 评价
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Nitrogen interception in floodwater of rice field in Taihu region of China 被引量:16
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作者 LIANG Xin-qiang CHEN Ying-xu LI Hua TIAN Guang-ming ZHANG Zhi-jian NI Wu-zhong HE Miao-miao 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2007年第12期1474-1481,共8页
A field experiment located in Taihu Lake Basin of China was conducted, by application of urea or a mixture of urea with manure, to elucidate the interception of nitrogen (N) export in a typical rice field through "... A field experiment located in Taihu Lake Basin of China was conducted, by application of urea or a mixture of urea with manure, to elucidate the interception of nitrogen (N) export in a typical rice field through "zero-drainage water management" combined with sound irrigation, rainfall forecasting and field drying. N concentrations in floodwater rapidly declined before the first event of field drying after three split fertilizations, and subsequently tended to rearm to the background level. Before the first field drying, total particulate nitrogen (TPN) was the predominant N form in floodwater of plots with no N input, dissolved inorganic nitrogen (DIN) on plots that received urea only, and dissolved organic nitrogen (DON) on plots treated with the mixture of urea and manure. Thereafter TPN became the major form. No N export was found from the rice field, but total nitrogen (TN) of 15.8 kg/hm^2 was remained, mainly due to soil N sorption. The results recommended the zero-drainage water management for full-scale areas for minimizing N export. 展开更多
关键词 NITROGEN paddy field surface floodwater interceptION Taihu region
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Novel TPN control algorithm for exoatmospheric intercept 被引量:14
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作者 Chen Lei Zhang Bing 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2009年第6期1290-1295,共6页
A novel control algorithm with fixed pulse thrust, based on true proportional navigation(TPN), is proposed for exoatmospheric intercept.According to the TPN guidance law and pulse thrust characteristics, the princip... A novel control algorithm with fixed pulse thrust, based on true proportional navigation(TPN), is proposed for exoatmospheric intercept.According to the TPN guidance law and pulse thrust characteristics, the principle of control command is presented, the control stability and precision are analyzed.With the help of the TPN guidance law, the algorithm can automatically modulate the turn-on time and duration of the thrust, which could effectively limit the impact of measure noise of the line-of-sight(LOS) angle and rate on the interception miss-distance.At last, the number-theoretic method(NTM) is introduced to acquire the relation between control algorithm and miss-distance, even as it simulates the intercept process with initial state noise.And the reliability of the algorithm is demonstrated with the simulation result. 展开更多
关键词 exoatmospheric intercept true proportional navigation pulse thrust control algorithm numbertheoretic method.
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Mulching mode and planting density affect canopy interception loss of rainfall and water use efficiency of dryland maize on the Loess Plateau of China 被引量:8
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作者 ZHENG Jing FAN Junliang +4 位作者 ZHANG Fucang YAN Shicheng GUO Jinjin CHEN Dongfeng LI Zhijun 《Journal of Arid Land》 SCIE CSCD 2018年第5期794-808,共15页
High and efficient use of limited rainwater resources is of crucial importance for the crop production in arid and semi-arid areas. To investigate the effects of different soil and crop management practices(i.e., mul... High and efficient use of limited rainwater resources is of crucial importance for the crop production in arid and semi-arid areas. To investigate the effects of different soil and crop management practices(i.e., mulching mode treatments: flat cultivation with non-mulching, flat cultivation with straw mulching, plastic-covered ridge with bare furrow and plastic-covered ridge with straw-covered furrow; and planting density treatments: low planting density of 45,000 plants/hm^2, medium planting density of 67,500 plants/hm^2 and high planting density of 90,000 plants/hm^2) on rainfall partitioning by dryland maize canopy, especially the resulted net rainfall input beneath the maize canopy, we measured the gross rainfall, throughfall and stemflow at different growth stages of dryland maize in 2015 and 2016 on the Loess Plateau of China. The canopy interception loss was estimated by the water balance method. Soil water storage, leaf area index, grain yield(as well as it components) and water use efficiency of dryland maize were measured or calculated. Results showed that the cumulative throughfall, cumulative stemflow and cumulative canopy interception loss during the whole growing season accounted for 42.3%–77.5%, 15.1%–36.3% and 7.4%–21.4% of the total gross rainfall under different treatments, respectively. Soil mulching could promote the growth and development of dryland maize and enhance the capability of stemflow production and canopy interception loss, thereby increasing the relative stemflow and relative canopy interception loss and reducing the relative throughfall. The relative stemflow and relative canopy interception loss generally increased with increasing planting density, while the relative throughfall decreased with increasing planting density. During the two experimental years, mulching mode had no significant influence on net rainfall due to the compensation between throughfall and stemflow, whereas planting density significantly affected net rainfall. The highest grain yield and water use efficiency of dryland maize were obtained under the combination of medium planting density of 67,500 plants/hm^2 and mulching mode of plastic-covered ridge with straw-covered furrow. Soil mulching can reduce soil evaporation and retain more soil water for dryland maize without reducing the net rainfall input beneath the maize canopy, which may alleviate the contradiction between high soil water consumption and insufficient rainfall input of the soil. In conclusion, the application of medium planting density(67,500 plants/hm^2) under plastic-covered ridge with bare furrow is recommended for increasing dryland maize production on the Loess Plateau of China. 展开更多
关键词 dryland maize THROUGHFALL STEMFLOW canopy interception loss yield water use efficiency Loess Plateau
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Combined proportional navigation law for interception of high-speed targets 被引量:4
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作者 Yuan LI Liang YAN +2 位作者 Ji-guang ZHAO Fan LIU Tao WANG 《Defence Technology(防务技术)》 SCIE EI CAS 2014年第3期298-303,共6页
A new proportional navigation(PN) guidance law,called combined proportional navigation(CPN),is proposed.The guidance law is designed to intercept high-speed targets,which is a common case for ballistic targets.The ran... A new proportional navigation(PN) guidance law,called combined proportional navigation(CPN),is proposed.The guidance law is designed to intercept high-speed targets,which is a common case for ballistic targets.The range of target-to-interceptor speed ratio during target interception is derived when guidance laws are applied in high-speed targets interception,and the effectiveness of negative navigation ratio in the PN-based guidance law is proven analytically in some lemmas.Based on the lemmas,the lateral acceleration command of CPN is defined,and the solution to the appearance of singularity in time-varying navigation ratio is given.The simulation results show that CPN can determine headon engagement(as PN) or tail-chase engagement(as RPN) through initial path angle compared with PN and retro proportional navigation(RPN),and can adjust the value of navigation ratio for head-on engagement or tail-chase engagement.Therefore,the capture region of CPN is larger than that of other guidance laws using PN-based methods. 展开更多
关键词 COMBINED proportional NAVIGATION Proportional NAVIGATION HIGH-SPEED target CAPTURE region interceptION
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Improving the Vegetation Dynamic Simulation in a Land Surface Model by Using a Statistical-dynamic Canopy Interception Scheme 被引量:3
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作者 梁妙玲 谢正辉 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2008年第4期610-618,共9页
Canopy interception of incident precipitation, as a critical component of a forest's water budget, can affect the amount of water available to the soil, and ultimately vegetation distribution and function. In this pa... Canopy interception of incident precipitation, as a critical component of a forest's water budget, can affect the amount of water available to the soil, and ultimately vegetation distribution and function. In this paper, a statistical-dynamic approach based on leaf area index and statistical canopy interception is used to parameterize the canopy interception process. The statistical-dynamic canopy interception scheme is implemented into the Community Land Model with dynamic global vegetation model (CLM-DGVM) to improve its dynamic vegetation simulation. The simulation for continental China by the land surface model with the new canopy interception scheme shows that the new one reasonably represents the precipitation intercepted by the canopy. Moreover, the new scheme enhances the water availability in the root zone for vegetation growth, especially in the densely vegetated and semi-arid areas, and improves the model's performance of potential vegetation simulation. 展开更多
关键词 canopy interception vegetation dynamics soil water land surface model
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Estimating light interception using the color attributes of digital images of cotton canopies 被引量:3
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作者 XUE Hui-yun HAN Ying-chun +6 位作者 LI Ya-bing WANG Guo-ping FENG Lu FAN Zheng-yi DU Wen-li YANG Bei-fang MAO Shu-chun 《Journal of Integrative Agriculture》 SCIE CAS CSCD 2017年第7期1474-1485,共12页
Crop growth and yield depend on canopy light interception (LI). To identify a low-cost and relatively efficient index for measuring LI, several color attributes of red-green-blue (RGB), hue-saturation-intensity (... Crop growth and yield depend on canopy light interception (LI). To identify a low-cost and relatively efficient index for measuring LI, several color attributes of red-green-blue (RGB), hue-saturation-intensity (HSI), hue-saturation-value (HSV) color models and the component values of color attributes in the RGB color model were investigated using digital images at six cotton plant population densities in 2012-2014. The results showed that the LI values followed downward quadratic curves after planting. The red (R), green (G) and blue (B) values varied greatly over the years, in accordance with Cai's research demonstrating that the RGB model is affected by outside light. Quadratic curves were fit to these color attributes at six plant population densities. Additionally, linear regressions of LI on every color attribute revealed that the hue (H) values in HSI and HSV were significantly linearly correlated with LI with a determination coefficient (R2)〉0.89 and a root mean square error (RMSE)=0.05. Thus, the H values in the HSI and HSV models could be used to measure LI, and this hypothesis was validated. The H values are new indexes for quantitatively estimating the LI of heterogeneous crop cano- pies, which will provide a theoretical basis for optimizing the crop canopy structure. However, further research should be conducted in other crops and under other growing and environmental conditions to verify this finding. 展开更多
关键词 canopy light interception (LI) digital image color attributes HUE
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Sensor radiation interception risk control in target tracking 被引量:4
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作者 Ce Pang Gan-lin Shan +1 位作者 Wei-ning Ma Gong-guo Xu 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2020年第3期695-704,共10页
This paper is mainly on the problem of radiation interception risk control in sensor network for target tracking.Firstly,the sensor radiation interception risk is defined as the product of the interception probability... This paper is mainly on the problem of radiation interception risk control in sensor network for target tracking.Firstly,the sensor radiation interception risk is defined as the product of the interception probability and the cost caused by the interception.Secondly,the radiation interception probability model and cost model are established,based on which the calculation method of interception risk can be obtained.Thirdly,a sensor scheduling model of radiation risk control is established,taking the minimum interception risk as the objective function.Then the Hungarian algorithm is proposed to obtain sensor scheduling scheme.Finally,simulation experiments are mad to prove the effectiveness of the methods proposed in this paper,which shows that compared with the sensor radiation interception probability control method,the interception risk control method can keep the sensor scheduling scheme in low risk as well as protect sensors of importance in the sensor network. 展开更多
关键词 Radio frequency stealth Target tracking interception probability interception risk Hungary algorithm
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Characteristics of canopy interception and its simulation with a revised Gash model for a larch plantation in the Liupan Mountains, China 被引量:2
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作者 Zebin Liu Yanhui Wang +7 位作者 Ao Tian Yu Liu Ashley A.Webb Yarui Wang Haijun Zuo Pengtao Yu Wei Xiong Lihong Xu 《Journal of Forestry Research》 SCIE CAS CSCD 2018年第1期187-198,共12页
Canopy interception is a significant proportion of incident rainfall and evapotranspiration of forest ecosystems. Hence, identifying its magnitude is vital for studies of eco-hydrological processes and hydrological im... Canopy interception is a significant proportion of incident rainfall and evapotranspiration of forest ecosystems. Hence, identifying its magnitude is vital for studies of eco-hydrological processes and hydrological impact evaluation. In this study, throughfall, stemflow and interception were measured in a pure Larix principis-rupprechtii Mayr.(larch) plantation in the Liupan Mountains of northwestern China during the growing season(May–October) of 2015, and simulated using a revised Gash model. During the study period, the total precipitation was 499.0 mm; corresponding total throughfall, stemflow and canopy interception were 410.3, 2.0 and 86.7 mm,accounting for 82.2, 0.4 and 17.4% of the total precipitation, respectively. With increasing rainfall, the canopy interception ratio of individual rainfall events decreased initially and then tended to stabilize. Within the study period, the simulated total canopy interception, throughfall and stemflow were 2.2 mm lower, 2.5 mm higher and 0.3 mm lower than their measured values, with a relative error of 2.5, 0.6 and 15.0%, respectively. As quantified by the model, canopy interception loss(79%) mainly consisted of interception caused by canopy adsorption, while the proportions of additional interception and trunk interception were small. The revised Gash model was highly sensitive to the parameter of canopy storage capacity,followed by the parameters of canopy density and mean rainfall intensity, but less sensitive to the parameters of mean evaporation rate, trunk storage capacity, and stemflow ratio. The revised Gash model satisfactorily simulated the total canopy interception of the larch plantation within the growing season but was less accurate for some individual rainfall events, indicating that some flaws exist in the model structure. Further measures to improve the model’s ability in simulating the interception of individual rainfall events were suggested. 展开更多
关键词 Canopy interception Larch plantation Revised Gash model STEMFLOW THROUGHFALL
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Interception of sulfate deposition from a closed canopy to a forest gap edge canopy in a subalpine dragon spruce plantation 被引量:1
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作者 ZHANG Yu WU Fu-zhong +7 位作者 TAN Bo XU Zhen-feng LI Han LIU Jun-cheng ZHAO Hai-rong TAN Si-yi YOU Cheng-ming YANG Wan-qin 《Journal of Mountain Science》 SCIE CSCD 2019年第12期2856-2866,共11页
Reducing the threats of sulfate ion(SO42-)deposition to terrestrial ecosystems is a great challenge.The canopy interception effect on SO42-deposition has been well documented,but the interception efficiency of the gap... Reducing the threats of sulfate ion(SO42-)deposition to terrestrial ecosystems is a great challenge.The canopy interception effect on SO42-deposition has been well documented,but the interception efficiency of the gap edge remains unknown.Therefore,a subalpine dragon spruce(Picea asperata)plantation was evaluated in the upper reaches of the Yangtze River.The dynamics of the SO42-concentration in the throughfall were investigated from the gap edge to the closed canopy during the rainfall and snowfall periods from August 2015 to July 2016.The annual input of SO42-totaled 2.56 kg/ha through rainfall and 0.69 kg/ha through snowfall.The total annual net interception fluxes(NIFs)of SO42-at the gap edge and in the closed canopy were 1.48 kg/ha and 0.66 kg/ha,respectively,and the net interception ratios(NIRs)accounted for 45.40%and 20.25%,respectively.The NIF and the NIR of SO42-at the gap edge were higher than those in the closed canopy.Therefore,the results suggested that a significant amount of SO42-deposition was intercepted by the tree canopy in the subalpine plantation,with more SO42-deposition at the gap edge than in the closed canopy,which is beneficial for improving the water quality in the upper reaches of the Yangtze River via forest management. 展开更多
关键词 Canopy interception Sulfate ion THROUGHFALL Gap edge Closed canopy Picea asperata
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‘Relationships between relationships’ in forest stands: intercepts and exponents analyses 被引量:1
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作者 Vladimir L.Gavrikov 《Journal of Forestry Research》 SCIE CAS CSCD 2018年第3期575-582,共8页
Relationships between diameter at breast height(dbh) versus stand density, and tree height versus dbh(height curve) were explored with the aim to find if there were functional links between correspondent parameters of... Relationships between diameter at breast height(dbh) versus stand density, and tree height versus dbh(height curve) were explored with the aim to find if there were functional links between correspondent parameters of the relationships, exponents and intercepts of their power functions. A geometric model of a forest stand using a conic approximation suggested that there should be interrelations between correspondent exponents and intercepts of the relationships. It is equivalent to a type of ‘relationship between relationships’ that might exist in a forest stand undergoing self-thinning, and means that parameters of one relationship may be predicted from parameters of another. The predictions of the model were tested with data on forest stand structure from published databases that involved a number of trees species and site quality levels. It was found that the correspondent exponents and intercepts may be directly recalculated from one another for the simplest case when the total stem surface area was independent of stand density. For cases where total stem surface area changes with the drop of density, it is possible to develop a generalization of the model in which the interrelationships between correspondent parameters(exponents and intercepts) may be still established. 展开更多
关键词 Total stem surface area SELF-THINNING Conic approximation Power function Exponent intercept Scots pine
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Design of synthetic aperture radar low-intercept radio frequency stealth 被引量:10
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作者 CHANG Wensheng TAO Haihong +1 位作者 LIU Yanbin SUN Guangcai 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2020年第1期64-72,共9页
Not confined to a certain point,such as waveform,this paper systematically studies the low-intercept radio frequency(RF)stealth design of synthetic aperture radar(SAR)from the system level.The study is carried out fro... Not confined to a certain point,such as waveform,this paper systematically studies the low-intercept radio frequency(RF)stealth design of synthetic aperture radar(SAR)from the system level.The study is carried out from two levels.In the first level,the maximum low-intercept range equation of the conventional SAR system is deduced firstly,and then the maximum low-intercept range equation of the multiple-input multiple-output SAR system is deduced.In the second level,the waveform design and imaging method of the low-intercept RF SAR system are given and verified by simulation.Finally,the main technical characteristics of the lowintercept RF stealth SAR system are given to guide the design of low-intercept RF stealth SAR system. 展开更多
关键词 synthetic aperture radar(SAR)imaging low-intercept radio frequency(RF)stealth low-intercept range low-intercept waveform
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Genotypic variation in spatiotemporal distribution of canopy light interception in relation to yield formation in cotton 被引量:3
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作者 XING Fangfang HAN Yingchun +10 位作者 FENG Lu ZHI Xiaoyu WANG Guoping YANG Beifang FAN Zhengyi LEI Yaping DU Wenli WANG Zhanbiao XIONG Shiwu LI Xiaofei Ll Yabing 《Journal of Cotton Research》 2018年第3期20-29,共10页
Background: Within-canopy interception of photosynthetically active radiation(PAR) impacts yield and other agronomic traits in cotton(Gossypium hirsutum L.). Field experiments were conducted to investigate the influen... Background: Within-canopy interception of photosynthetically active radiation(PAR) impacts yield and other agronomic traits in cotton(Gossypium hirsutum L.). Field experiments were conducted to investigate the influence of 6 cotton varieties(they belong to 3 different plant types) on yield, yield distribution, light interception(LI), LI distribution and the relationship between yield formation and LI in Anyang, Henan, in 2014 and 2015.Result: The results showed that cotton cultivars with long branches(loose-type) intercepted more LI than did cultivars with short branches(compact-type), due to increased LI in the middle and upper canopy. Although loose-type varieties had greater LI, they did not yield significantly higher than compact-type varieties, due to decreased harvest index. Therefore, improving the harvest index by adjusting the source-to-sink relationship may further increase cotton yield for loose-type cotton. In addition, there was a positive relationship between reproductive organ biomass accumulation and canopy-accumulated LI, indicating that enhancing LI is important for yield improvement for each cultivar. Furthermore, yield distribution within the canopy was significantly linearly related to vertical LI distribution.Conclusion: Therefore, optimizing canopy structure of different plant type and subsequently optimizing LI distribution within the cotton canopy can effectively enhance the yield. 展开更多
关键词 Cotton cultivars Light interception Plant type structure Boll distribution YIELD
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Optimal multilevel thresholding based on molecular kinetic theory optimization algorithm and line intercept histogram 被引量:3
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作者 范朝冬 任柯 +1 位作者 张英杰 易灵芝 《Journal of Central South University》 SCIE EI CAS CSCD 2016年第4期880-890,共11页
Among all segmentation techniques, Otsu thresholding method is widely used. Line intercept histogram based Otsu thresholding method(LIH Otsu method) can be more resistant to Gaussian noise, highly efficient in computi... Among all segmentation techniques, Otsu thresholding method is widely used. Line intercept histogram based Otsu thresholding method(LIH Otsu method) can be more resistant to Gaussian noise, highly efficient in computing time, and can be easily extended to multilevel thresholding. But when images contain salt-and-pepper noise, LIH Otsu method performs poorly. An improved LIH Otsu method(ILIH Otsu method) is presented, which can be more resistant to Gaussian noise and salt-and-pepper noise. Moreover, it can be easily extended to multilevel thresholding. In order to improve the efficiency, the optimization algorithm based on the kinetic-molecular theory(KMTOA) is used to determine the optimal thresholds. The experimental results show that ILIH Otsu method has stronger anti-noise ability than two-dimensional Otsu thresholding method(2-D Otsu method), LIH Otsu method, K-means clustering algorithm and fuzzy clustering algorithm. 展开更多
关键词 image segmentation multilevel thresholding Otsu thresholding method kinetic-molecular theory (KMTOA) line intercept histogram
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An improved CFD model of gas flow and particle interception in a fiber material 被引量:2
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作者 Zhiwei Sun Jianhui Wen +3 位作者 Xiao Luo Wen Du Zhiwu Liang Kaiyun Fu 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2017年第3期264-273,共10页
An improved CFD model of gas flow and particle interception in a fiber material which fiber size is Y-shape was developed in this work. The porous medium model was used to build the model of the whole size of fiber fi... An improved CFD model of gas flow and particle interception in a fiber material which fiber size is Y-shape was developed in this work. The porous medium model was used to build the model of the whole size of fiber filter medium. Mixture model was adopted. The algorithm of particle interception in the whole size of fiber filter medium was derived and UDF(User Defined Function) that described kinds of particle filtering mechanisms in filter fibrous media was added to the Fluent default conservation equation as source term for simulation. The inertial resistance of the filter was taken into consideration, which provided a more precise measurement of the smoke flow and the particle interception in the filter under higher smoke speed conditions. The commercial software, Fluent 6.3, was used to simulate the smoke flow and particle interception in the filter in a single suction. The velocity and pressure profiles of smoke or nicotine particle in the filter, as well as nicotine particle volume fraction profile were well simulated. Finally, the comparisons of nicotine particle filtration efficiency between Fluent simulation results in this work and experimental results, as well as the model prediction in the literature were made to validate the simulation model. The comparisons showed that the particle entrapment model from simulation results was in good agreement with that from the experimental results. In addition, the Fluent simulation results are closer to reality both at the beginning and the end of the smoke process comparing with the model predicted results in the literature. 展开更多
关键词 Numerical simulation Y-shape fiber Particle interception Flow field distribution Filtration efficiency UDF
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A guidance method for coplanar orbital interception based on reinforcement learning 被引量:4
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作者 ZENG Xin ZHU Yanwei +1 位作者 YANG Leping ZHANG Chengming 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2021年第4期927-938,共12页
This paper investigates the guidance method based on reinforcement learning(RL)for the coplanar orbital interception in a continuous low-thrust scenario.The problem is formulated into a Markov decision process(MDP)mod... This paper investigates the guidance method based on reinforcement learning(RL)for the coplanar orbital interception in a continuous low-thrust scenario.The problem is formulated into a Markov decision process(MDP)model,then a welldesigned RL algorithm,experience based deep deterministic policy gradient(EBDDPG),is proposed to solve it.By taking the advantage of prior information generated through the optimal control model,the proposed algorithm not only resolves the convergence problem of the common RL algorithm,but also successfully trains an efficient deep neural network(DNN)controller for the chaser spacecraft to generate the control sequence.Numerical simulation results show that the proposed algorithm is feasible and the trained DNN controller significantly improves the efficiency over traditional optimization methods by roughly two orders of magnitude. 展开更多
关键词 orbital interception reinforcement learning(RL) Markov decision process(MDP) deep neural network(DNN)
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The impact of plant density and spatial arrangement on light interception on cotton crop and seed cotton yield:an overview 被引量:6
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作者 CHAPEPA Blessing MUDADA Nhamo MAPURANGA Rangarirai 《Journal of Cotton Research》 2020年第3期210-215,共6页
Light attenuation within a row of crops such as cotton is influenced by canopy architecture,which is defined by size,shape and orientation of shoot components.Level of light interception causes an array of morpho-anat... Light attenuation within a row of crops such as cotton is influenced by canopy architecture,which is defined by size,shape and orientation of shoot components.Level of light interception causes an array of morpho-anatomical,physiological and biochemical changes.Physiological determinants of growth include light interception,light use efficiency,dry matter accumulation,duration of growth and dry matter partitioning.Maximum light utilization in cotton production can be attained by adopting cultural practices that yields optimum plant populations as they affect canopy arrangement by modifying the plant canopy components.This paper highlights the extent to which spatial arrangement and density affect light interception in cotton crops.The cotton crop branches tend to grow into the inter-row space to avoid shade.The modification of canopy components suggests a shade avoidance and competition for light.Maximum leaf area index is obtained especially at flowering stage with higher populations which depicts better yields in cotton production. 展开更多
关键词 Light interception Plant populations Spatial arrangement Canopy architecture
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