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Diagnostics of temperature and blue-shifted velocity using soft X-ray spectra from the Macao Science Satellite-1 被引量:2
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作者 JianPing Li Xu Yang +6 位作者 Dong Li JinHua Shen Lei Yang Ya Wang LianSheng Li YongQiang Shi HaiSheng Ji 《Earth and Planetary Physics》 2025年第3期740-751,共12页
Using the new soft X-ray data from the Macao Science Satellite-1,we studied a solar flare that occurred on 22 June 2023.We found that the centroids of the Ca(around 3.9 keV)and Fe(around 6.7 keV)line features exhibit ... Using the new soft X-ray data from the Macao Science Satellite-1,we studied a solar flare that occurred on 22 June 2023.We found that the centroids of the Ca(around 3.9 keV)and Fe(around 6.7 keV)line features exhibit a rapid shift toward higher energy channels during the flare's rising phase,followed by a gradual decrease during the decay phase.Through precise energy calibration,the centroids are determined with high accuracy.Temperature and velocity are then self-consistently derived by comparing the centroids with those calculated from the synthesized line features using the latest CHIANTI atomic database(ver.10.1).The calculated maximum velocity reaches up to 710±60 km s-1,which significantly exceeds the previously reported values.Our results suggest that the entire shift of soft X-ray lines may occur during the process of chromospheric evaporation. 展开更多
关键词 Macao Science Satellite-1 solar flares soft X-ray lines chromospheric evaporation
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Surveying Organic Matter,Thermal Maturity Level,and Paleo-Environmental Conditions by Considering Biomarker and Stable Carbon Isotopic Analysis 被引量:1
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作者 Meysam Hemmati Yaser Ahmadi +2 位作者 Behzad Vaferi Ali Hosin Alibak David A.Wood 《Journal of Earth Science》 2025年第2期428-440,共13页
Biomarker and stable carbon isotope analyses are presented for the Garau Formation of the Cretaceous Age,an important source rock in western Iran,to reveal its potential as an oilprone source rock.The C_(28)/C_(29)ste... Biomarker and stable carbon isotope analyses are presented for the Garau Formation of the Cretaceous Age,an important source rock in western Iran,to reveal its potential as an oilprone source rock.The C_(28)/C_(29)sterane ratio value range(0.72 to 0.83)of bitumen samples from the formation suggests that they were likely formed during phytoplankton blooms.Sterane,hopane,and isoprenoid/n-alkane ratios indicate that the formation's organic matter predominantly consists of algae,and bacteria,accompanied by some reworked material derived from higher plants.Due to the predominance of anoxic conditions and the actions of sulfate-reducing bacteria,the bitumen present is enriched with sulfur compounds.The percentages of saturates,aromatics,and nitrogen-sulfuroxygen(NSO)fractions in the bitumen samples classify them as naphthenic oils.Isotope analysis reveals that biodegradation and water-washing have reduced the concentrations of some volatile saturates and low molecular weight aromatics in the bitumen samples.These actions have resulted in distinctiveδ^(13)C values for the formation's kerogen and bitumen fractions.The formation's organic matter has been subjected to high-temperature thermal regimes and has entered the oil-generation window at the sampled localities,with vitrinite reflectance(%R_(C))varying between 0.7%and 0.75%. 展开更多
关键词 source-rock geochemistry biomarkers stable carbon isotopes alteration processes naphthenic crude oil petroleum geology
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Strength of parrot fight feathers is a function of positionon the wing
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作者 Denis Charles Deeming Connor J.Hutchings +1 位作者 Fern G.Seaward Adrian M.Goodman 《Current Zoology》 2025年第2期212-222,共11页
Powered fight in birds is reliant on feathers forming an aerodynamic surface that resists air pressures.Many basic aspects of feather functionality are unknown,which hampers our understanding of wing function in birds... Powered fight in birds is reliant on feathers forming an aerodynamic surface that resists air pressures.Many basic aspects of feather functionality are unknown,which hampers our understanding of wing function in birds.This study measured the dimensions of primary and secondaryfight feathers of 19 species of parrots.The maximum force the feathers could withstand from below was also measured to mimic the pressuresexperienced during a downstroke.The analysis tested whether:(1)feather dimensions differed along the wing and among secondary and primary remiges;(2)the force that feathers could withstand varied among the remiges;and(3)there would be isometric relationships with bodymass for feather characteristics.The results show that body mass signifcantly affected vane width,rachis thickness,maximum force,and ultimate bending moment,but the relationship for feather length only approached signifcance.Many of the proximal secondary feathers showedsignifcantly lower values relative to the frst primary,whereas for distal primaries the values were greater.There were isometric relationships forforce measurements of primary and secondary feathers with body mass,but there was positive allometry for feather lengths and vane widths.The forces feathers can withstand vary along the wing may be a proxy for the aerodynamic properties of the feathers in situ.Broader taxonomicstudies that explore these topics are required for other species representing a range of different orders.A better understanding of the functionality of feathers will improve our understanding of how avian fight works particularly considering the variety in fight style and wing shape in birds. 展开更多
关键词 bending moment dimensions FEATHER force primary SECONDARY
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Size of the ulna and taxonomic order affect vane dimensions of secondary remiges in birds
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作者 D.C.Deeming E.P.Bayliss E.Ketley 《Avian Research》 2025年第2期284-290,共7页
The number of secondary feathers varies among orders of birds with some orders exhibiting a positive relationship with ulna length,whereas in other orders secondary number is invariant.This difference has implications... The number of secondary feathers varies among orders of birds with some orders exhibiting a positive relationship with ulna length,whereas in other orders secondary number is invariant.This difference has implications for scaling of the width of the feather vane within orders.In those species where the number of secondary remiges is invariant with ulna length,vane width should scale isometrically with ulna size to maintain an aerodynamic flight surface.Where feather count increases with increasing ulna length then vane width should exhibit negative allometry.Vane length should also correlate with ulna length,irrespective of the number of feathers.Data were compiled from an online library of images for the vane length and the width of the vane at 50%of the vane length for the fifth secondary feather for 209 bird species from 24 different orders.The results supported the hypotheses that vane width is a function of ulna size,and the number of secondary feathers as associated with different orders.Vane length was unaffected by the number of secondaries but varied between orders.The results suggest that birds have solved the problem of maintaining the aerodynamic surface of the proximal wing in two ways.Hence as ulna length increases the first solution involves more feathers that exhibit negative allometry for vane width,or in the second where feather count doesn't change,the vane width simply scales isometrically.The implications for the mechanical properties of the vane,and how it affects wing function,have not yet been explored in a range of birds. 展开更多
关键词 AVIAN FEATHER Secondary remiges Ulna length Vane length Vane width
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Traffic Problems in Michigan and Using Intelligent Transportation Systems to Solve
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作者 Chaudhry Abu Bakar Imran 《Journal of Traffic and Transportation Engineering》 2025年第1期17-27,共11页
The aim of this study is to determine the level to which the public is aware about ITS(intelligent transportation systems)technologies and how they perceive the potential advantages and inhibitors of ITS in Michigan.A... The aim of this study is to determine the level to which the public is aware about ITS(intelligent transportation systems)technologies and how they perceive the potential advantages and inhibitors of ITS in Michigan.A survey was performed with 200 participants living in Michigan,in urban,suburban and rural areas.Questions covered in the survey included how often and how bad traffic congestion occurred,how familiar travelers were with ITS technologies(adaptive traffic signals,real time monitoring of the traffic)and how much support travelers would provide for ITS initiatives.Results reveal that there is a high degree of traffic congestion awareness,there is low public awareness of ITS technologies.While respondents who were aware of ITS solutions had positive views about deploying them,especially in urban areas,they were less supportive of ITS solutions than they were among those who did not know much about these.Factors including area of residence,commute time and age were perceived to influence ITS along with more positive attitudes to ITS amongst urban dwellers and younger respondents.Analysis of key barriers to ITS implementation reflected high initial costs,challenges with technical integration and users’concerns surrounding privacy. 展开更多
关键词 Traffic congestion ITS ITS awareness public perception traffic management MICHIGAN SURVEY environmental impact economic benefits public support
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Nest attentiveness does not impact incubation duration across different bird species
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作者 D.Charles Deeming 《Avian Research》 2025年第3期338-344,共7页
Avian incubation is characterised by the contact between the eggs and the bird's skin to transfer heat to increase egg temperature above ambient conditions. Birds can be attentive to the clutch all of the time or,... Avian incubation is characterised by the contact between the eggs and the bird's skin to transfer heat to increase egg temperature above ambient conditions. Birds can be attentive to the clutch all of the time or, particularly if only one parent incubates, attentiveness may be quite low. Attentiveness is related to egg size with large eggs having high attentiveness, whereas small eggs (<10 g) can have attentiveness ranging from 50% to 100%. Previous studies have suggested that incubation duration is a function of attentiveness albeit for small birds. This study tested the hypothesis that, after controlling for egg size and phylogeny, incubation duration would be a function of attentiveness. Data for 444 bird species representing 24 orders were analysed. Whilst egg mass had a significant relationship with incubation duration, there was no relationship with attentiveness for all of the species or a subset of the passerines. Despite egg temperature drops during an incubation recess, average day-time and night-time temperatures are similar in a range of species. Re-examination of previously reported temperature profiles recorded by dummy eggs over a 24-h period shows that after an incubation recess there seems to be an additional heat flux that raises egg temperature above that seen during night-time periods of constant incubation. The reasons why eggs under intermittent incubation are not considerably cooler than eggs during constant incubation are discussed. 展开更多
关键词 Egg temperature Heat flux Incubation duration Nest attentiveness PHYLOGENY
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Death after psychiatric contraindications to urgent liver transplant for paracetamol overdose
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作者 Olivia R E Impey Jennifer D Baker +1 位作者 Roger S Smyth Stephen G Potts 《World Journal of Transplantation》 2025年第3期110-115,共6页
BACKGROUND Paracetamol overdose(POD)is the most common cause of acute hepatic failure(AHF)in the United Kingdom.Without urgent orthotopic liver transplant(OLT),mortality is high.Psychiatric assessment for transplant i... BACKGROUND Paracetamol overdose(POD)is the most common cause of acute hepatic failure(AHF)in the United Kingdom.Without urgent orthotopic liver transplant(OLT),mortality is high.Psychiatric assessment for transplant is time-pressured and often undertaken by psychiatrists without transplant experience.Assessors may identify absolute psychiatric contraindications(APCIs)precluding transplant in otherwise medically suitable patients.It is unknown how often this occurs.The combination of high but unknown mortality,time pressure,and relative inexperience is likely to provoke anxiety in assessors.This study hypothesised that the proportion of POD patients assessed for OLT who die because psychiatric contraindications preclude transplant would be small but not negligible.AIM To determine the proportion of patients with paracetamol-induced AHF,for whom psychiatric contraindications preclude transplantation,and the consequent mortality.METHODS This is an 18-year single-centre retrospective cohort study based in a national liver transplant centre.524 participants were identified from a departmental database and included if they had AHF from suspected POD and received a psychiatric assessment for OLT.For those who died before discharge,records were reviewed for medical and psychiatric contraindications to transplant,alongside age,sex,and primary psychiatric diagnosis.We calculated the proportion of patients assessed for whom APCIs precluded transplant,resulting in death.RESULTS Among 524 patients undergoing psychiatric assessment for OLT,there were 102 in-episode deaths(19.5%).APCIs were identified in 46 patients who were otherwise medically suitable for transplant and went on to die.This statistic represents 8.8%of the number of persons evaluated and 45%of the number of deaths.Within this subgroup,27(59%)were female,with a mean age of 44.6 years(ranging from 19-72 years).The most common primary psychiatric diagnosis was alcohol dependence syndrome,which accounted for 67%(n=31).CONCLUSION 8.8%of medically suitable patients with AHF following POD died with APCIs to transplant.This indicates a need for ongoing assessor training and support,and(inter)national comparisons of practice. 展开更多
关键词 Paracetamol overdose Acute hepatic failure Orthotopic liver transplant Psychiatric contraindications Mortality
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Artificial Intelligence-Driven Advanced Wave Energy Planning and Control:Framework,Challenges and Perspectives
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作者 Bo Yang Guo Zhou +1 位作者 Shua Zhou Yaxing Ren 《Energy Engineering》 2025年第10期3905-3915,共11页
1 Introduction With the continuous increase in global population,the demand for energy is upgrading at an unprecedented rate.At present,fossil fuels dominate the global energy landscape,but their limitations lay the g... 1 Introduction With the continuous increase in global population,the demand for energy is upgrading at an unprecedented rate.At present,fossil fuels dominate the global energy landscape,but their limitations lay the groundwork for the upcoming global energy crisis[1].The non renewable nature of fossil fuels,coupled with increasing energy consumption,poses a significant threat to the long-term energy security of the world.In addition,the combustion of fossil fuels releases a large amount of air pollutants such as carbon dioxide and sulfur dioxide,leading to serious environmental pollution and climate change.These environmental issues have far-reaching impacts,including rising sea levels,extreme weather events,and loss of biodiversity[2–4]. 展开更多
关键词 Artificial intelligence wave energy WEC control hybrid planning
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Aging Dynamics in Polymer Powder Bed Fusion Systems:The Case of Selective Laser Sintering
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作者 Bruno Alexandre de Sousa Alves Dimitrios Kontziampasis Abdel-Hamid Soliman 《Additive Manufacturing Frontiers》 2025年第2期156-166,共11页
Additive manufacturing(AM)is an advanced production method for layer-by-layer fabrication,offering a paradigm shift in manufacturing.However,the sustainability of AM processes is poor,since suppliers recommend reusing... Additive manufacturing(AM)is an advanced production method for layer-by-layer fabrication,offering a paradigm shift in manufacturing.However,the sustainability of AM processes is poor,since suppliers recommend reusing 50%-70%of reprocessed powder,contributing to a significant increase in material disposal.To explore the possibility of fully reusing the polymeric material,we conduct a comprehensive characterisation of the powder particulates,in combination with analysis of the final prints.Utilizing optical and scanning electron microscopes,we statistically evaluate the size,morphology,and shape of the particles.Furthermore,tensile strength and deformation of printed bars is evaluated,showcasing the impact of aging on the print properties.The findings reveal that consecutive reuse of used powder significantly influences dimensional accuracy of the printed parts.We detect a 30.63%relative value of shrinkage after six printing iterations,which corresponds to an absolute shrinkage increase by 0.98%.This is significant considering the standard shrinkage for the material used is already 3.2%.Additionally,parts that are printed with reused material exhibit a small increase in elongation at yield,as well as an unexpected rise in tensile strength.Significant agglomeration of small particles is observed in the aged powder,since there are particles of less than 10μm,which are not found in the virgin powder.These results contribute to a better understanding of the issues related to the reusing of aged material,and offer invaluable insights for mitigating the environmental impact that is associated with material disposal in AM. 展开更多
关键词 Additive manufacturing 3D printing Powder bed fusion Selective laser sintering POLYMERS SUSTAINABILITY RECYCLING
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Renewable energy and its impact on agricultural and economic development in the Netherlands and South Africa
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作者 Saul NGARAVA Alois Aldridge MUGADZA 《Regional Sustainability》 2025年第2期1-16,共16页
The use ofrenewable energyisan important way toachieve sustainable agriculturalandeconomic development.However,there are differences in accessto renewable energy between the Global North and Global South.This study ut... The use ofrenewable energyisan important way toachieve sustainable agriculturalandeconomic development.However,there are differences in accessto renewable energy between the Global North and Global South.This study utilisedan autoregressive distributed lag-error correctionmodel and thedata spanning from 1991to 2021 to comparatively analyse the dynamic relationship amongrenewable energy consumption,the value of agricultural production,gross domestic product(GDP),economic diversificationindex,urban population,the total water extraction for agricultural withdrawal,and trade balancein the Netherlands and South Africa.In the shortrun,renewable energy consumption was increased by the value of agricultural productionbut decreased by GDPin South Africa.In the longrun,renewable energy consumption and GDP increased the value of agricultural production,while the value of agricultural production also increased GDP in South Africa.However,in the Netherlands,there was no short-and long-run relationship betweenrenewable energy consumption and agricultural and economic development.The results revealedthat there was a short-and long-run relationship in South Africa.Moreover,in the Netherlands,the adjustment speed was-1.46 forrenewable energy consumption with an error correction of 0.68 a(8.22 months).In South Africa,the adjustment speedwas-1.28 forrenewable energy consumption with an error correction of 0.78 a(9.38 months).Therefore,compared to South Africa,renewable energy consumptionin the Netherlands takes less time to return to balance after a shock.Thesefindings signify different trajectories on sectoral and economic transition initiatives spurred usingrenewable energy between the Netherlands and South Africa.Policy relating to initiatives such as“agro-energy communities”in Global South countries such as South Africa should be emphasised to promote the use of renewable energy in the agricultural sector. 展开更多
关键词 Autoregressive distributed lag-error correction model(ARDL-ECM) Renewable energy consumption Agricultural production Economic development The Netherlands South Africa
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Association between insulin and liver function tests,liver disease and cirrhosis in population-based cohorts with long term follow-up
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作者 Andreas Schult Kirsten Mehlig +5 位作者 Kurt Svärdsudd Sven Wallerstedt Cecilia Björkelund Per-Olof Hansson Henrik Zetterberg Jerzy Kaczynski 《World Journal of Hepatology》 2025年第6期104-115,共12页
BACKGROUND Insulin resistance is a cardiometabolic risk factor characterized by elevated insulin levels.It is associated with fatty liver disease and elevated liver function tests(LFT)in cross-sectional studies,but da... BACKGROUND Insulin resistance is a cardiometabolic risk factor characterized by elevated insulin levels.It is associated with fatty liver disease and elevated liver function tests(LFT)in cross-sectional studies,but data from cohort studies are scarce.AIM To investigate the association between insulin and pathological LFT,liver disease,and cirrhosis in a populationbased retrospective cohort study.METHODS Anthropometric and cardiometabolic factors of 857 men and 1228 women from prospective cohort studies were used.LFT were obtained at two time points 8 years to 24 years after baseline.Liver disease diagnoses were obtained from nationwide registries.The association between insulin levels and the development of elevated LFT or liver disease and cirrhosis was analyzed.RESULTS Total follow-up was 54054 person-years for women and 27556 person-years for men.Insulin levels were positively correlated with elevated LFT during follow-up,whereas physical activity and coffee consumption were negatively correlated.Individuals with both insulin levels in the upper tertile and alcohol consumption above MASLD thresholds had an increased risk for both liver disease,adjusted hazard ratio(aHR)of 4.3(95%CI:1.6-14.6)and cirrhosis(aHR=4.8,95%CI:1.6-14.6).CONCLUSION This population-based study provides evidence that high insulin levels are a risk factor for development of elevated liver enzymes and clinically manifest liver disease.The results support the concept of metabolic dysfunction associated liver disease. 展开更多
关键词 INSULIN Liver function tests ALCOHOL Metabolic dysfunction associated steatotic liver disease Liver cirrhosis
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基于人工流场的四轮转向自动驾驶集成控制算法 被引量:3
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作者 刘庆伟 GORDON Tim +1 位作者 RAHMAN Shammi 喻凡 《机械设计与研究》 CSCD 北大核心 2022年第4期138-144,共7页
提出了一种基于人工流场的四轮转向车辆自动驾驶路径跟踪集成控制算法。在确定的驱动、制动和侧向加速度约束下,规划了沿期望参考路径的速度轨迹。利用人工流场引导算法设计了质点模型沿参考路径的参考速度矢量生成算法,针对四轮转向车... 提出了一种基于人工流场的四轮转向车辆自动驾驶路径跟踪集成控制算法。在确定的驱动、制动和侧向加速度约束下,规划了沿期望参考路径的速度轨迹。利用人工流场引导算法设计了质点模型沿参考路径的参考速度矢量生成算法,针对四轮转向车辆,选定前后轴的中心为控制点,并设计了前馈+反馈的底层控制算法。利用MATLAB/Simulink和CarMaker搭建了仿真环境,并设计了连续曲率变化和大曲率变化两种典型工况,验证了所提出的控制算法的有效性。试验结果表明,在质心侧向加速度0.6g的极限工况下,控制算法可实现侧向跟踪误差和偏航角误差分别小于5 cm和4°。 展开更多
关键词 自动驾驶 路径跟踪 车辆动力学 集成控制
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一种尺度感知型遥感图像融合新方法 被引量:7
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作者 李旭 高雅楠 Shigang Yue 《宇航学报》 EI CAS CSCD 北大核心 2017年第12期1348-1353,共6页
针对在高分辨率星载遥感图像融合中容易出现的空间或光谱信息失真问题,提出一种基于滚动导向滤波的多光谱与全色光图像融合新方法。该方法采用主成分分析(PCA)设计融合模型,利用具有尺度感知特性的滚动导向滤波器准确地提取出多光谱... 针对在高分辨率星载遥感图像融合中容易出现的空间或光谱信息失真问题,提出一种基于滚动导向滤波的多光谱与全色光图像融合新方法。该方法采用主成分分析(PCA)设计融合模型,利用具有尺度感知特性的滚动导向滤波器准确地提取出多光谱图像第一主成分的大尺度结构信息和全色光图像的小尺度细节信息,然后将细节信息与结构信息相结合,经过主成分分析反变换得到融合结果。本文采用Geo Eye-1卫星数据进行试验,主观分析与客观评价表明,该方法能够在保持图像光谱信息的同时显著提高融合图像的空间分辨率,且融合质量优于现有的几种融合方法。 展开更多
关键词 滚动导向滤波器 图像融合 全色光图像 多光谱图像
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基于化学反应速率理论的绝缘聚合物直流老化演变的仿真研究 被引量:2
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作者 左周 姚陈果 +3 位作者 DISSADO L A 高岩峰 DODD S J CHALASHKANOV N M 《高电压技术》 EI CAS CSCD 北大核心 2020年第3期832-842,共11页
直流电场作用下绝缘聚合物老化演变的仿真研究,对促进计算高电压工程学的发展有重要的理论及工程价值。为此使用MATLAB自定义编程,在二维坐标中建立有限差分老化数值模型;用绝缘薄膜的老化寿命数据所拟合的小尺寸结构单元的通用参数,表... 直流电场作用下绝缘聚合物老化演变的仿真研究,对促进计算高电压工程学的发展有重要的理论及工程价值。为此使用MATLAB自定义编程,在二维坐标中建立有限差分老化数值模型;用绝缘薄膜的老化寿命数据所拟合的小尺寸结构单元的通用参数,表征大尺寸绝缘样品的材料不均匀性;并基于化学反应速率理论,量化计算绝缘老化过程。通过仿真发现,绝缘聚合物内部的薄弱点率先发生微小劣化,导致局部电场畸变;增强的局部电场进一步加速局部区域的老化进程,引起劣化区域的扩大与延伸;最终当局部场强达到临界值时,绝缘内部发生快速的击穿过程,并形成贯穿上下电极的细丝状导电路径,在靠近极板时由于局部电场分散性而出现分形的失效结构。该研究提出的数值仿真模型可高效、直观地反映绝缘聚合物老化过程中,从随机性局部劣化演变到确定性宏观失效的物理规律,为深入理解绝缘老化失效提供了理论参考和依据。 展开更多
关键词 计算高电压工程学 化学反应速率理论 材料不均匀性 老化 击穿 绝缘聚合物
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大鼠小体积肝移植后肝细胞再生的研究 被引量:1
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作者 何清 陈燕涛 +4 位作者 张红卫 谷艳丽 Uta Dahmen Olaf Dirsch 王捷 《岭南现代临床外科》 2005年第3期233-235,共3页
目的探讨小体积肝移植术后肝再生的情况。方法建立大鼠30%原位肝移植模型,实验分为肝切除(PH)组、全肝移植(OLT)组和30%小体积肝移植(30%POLT)组,观察1w生存率,并于术后1、2、3、7d检测肝细胞增殖活性、肝功能和肝组织学变化。结果各组1... 目的探讨小体积肝移植术后肝再生的情况。方法建立大鼠30%原位肝移植模型,实验分为肝切除(PH)组、全肝移植(OLT)组和30%小体积肝移植(30%POLT)组,观察1w生存率,并于术后1、2、3、7d检测肝细胞增殖活性、肝功能和肝组织学变化。结果各组1w生存率均为100%;30%POLT组术后2d达到增殖高峰,峰值与PH组无差异(P>0.05);其肝功能酶学指标在术后1、3d明显升高,组织学见肝细胞核分裂极其活跃。结论冷缺血1h的30%供肝和肝切除后肝脏具有同样的增殖活性,仅增殖高峰稍晚;较短的冷缺血时间以及熟练的手术技术可能对小体积供肝的再生起重要作用。 展开更多
关键词 小体积肝移植 肝再生 大鼠
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冷缺血对大鼠小体积肝移植肝再生的影响
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作者 何清 陈燕涛 +3 位作者 王捷 谷艳丽 Uta Dahmen Olaf Dirsch 《岭南现代临床外科》 2006年第3期170-172,共3页
目的探讨冷缺血对大鼠小体积肝移植术后肝再生的影响。方法本组在2002年9月~2004年8月利用大鼠肝总量30%原位肝移植模型,实验分为肝总量70%肝切除组(C组)和冷缺血1、3、5h组(E1、E2、E3组),观察1w生存率及肝重量/受体原肝重量比值(EGW/... 目的探讨冷缺血对大鼠小体积肝移植术后肝再生的影响。方法本组在2002年9月~2004年8月利用大鼠肝总量30%原位肝移植模型,实验分为肝总量70%肝切除组(C组)和冷缺血1、3、5h组(E1、E2、E3组),观察1w生存率及肝重量/受体原肝重量比值(EGW/RLW),并检测术后1、2、3、7d肝细胞增殖活性及肝组织学变化。结果E1组1w生存率及EGW/RLW分别达100%和95%,均明显高于E2、E3组(P均<0.05);E1、E2、E3组均于术后2d达到增殖高峰,其中E1组峰值显著高于E2、E3组(P<0.001),且与C组峰值无差异(P>0.05);组织学检查见E1组肝细胞核分裂明显活跃。结论冷缺血1h的小体积供肝和70%肝切除后肝脏具有同样的增殖活性,仅增殖高峰稍晚;冷缺血超过3h严重影响小体积供肝的再生能力和受者的存活率。 展开更多
关键词 冷缺血 小体积肝移植 肝再生
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基于Faster R-CNN的野外环境中蝗虫快速识别 被引量:4
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作者 武英洁 房世波 +4 位作者 Piotr Chudzik Simon Pearson Bashir Al-Diril 冯旭宇 李云鹏 《气象与环境学报》 2020年第6期137-143,共7页
蝗虫是常见的害虫之一,对农作物和生态系统具有很大的危害,采用常规的方法对蝗虫进行监测存在一定局限性,为了有效应用海量野外影像数据实现对蝗虫实时监测,本文建立了一种基于深度学习网络的蝗虫自动识别模型。利用手机模拟摄像头获取... 蝗虫是常见的害虫之一,对农作物和生态系统具有很大的危害,采用常规的方法对蝗虫进行监测存在一定局限性,为了有效应用海量野外影像数据实现对蝗虫实时监测,本文建立了一种基于深度学习网络的蝗虫自动识别模型。利用手机模拟摄像头获取的内蒙古锡林浩特附近草原的280张蝗虫的RGB图像,采用深度学习算法中的Faster R-CNN(Faster Region-based Convolutional Neural Network)网络结构建立了蝗虫识别模型。经验证该模型的精确度为0.756,可以较准确地将蝗虫从野外复杂环境中识别出来,与以往同类研究相比,在识别结果和实用性方面均有较大的进步。该模型是建立蝗虫实时监测系统的基础,可以为蝗虫的防治提供辅助信息,同时该网络结构还可以应用于其他害虫的识别,具有较强的推广性,拓宽了深度学习算法的应用领域。 展开更多
关键词 蝗虫 深度学习 识别 Faster R-CNN
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高次谐波大回旋太赫兹振荡器多模工作特性 被引量:2
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作者 赵其祥 马梦诗 +5 位作者 李想 吕游 张天钟 彭麟 王峨锋 冯进军 《红外与毫米波学报》 SCIE EI CAS CSCD 北大核心 2022年第2期457-463,共7页
设计了一支可工作于4~9次谐波的大回旋太赫兹振荡管,借助于三维粒子模拟,研究了设计的大回旋振荡管注-波互作用机理、高次谐波工作特性、谐波模式间竞争等关键特性。结果表明,通过调节磁场强度,可以在多个相邻谐波处连续激发振荡,实现... 设计了一支可工作于4~9次谐波的大回旋太赫兹振荡管,借助于三维粒子模拟,研究了设计的大回旋振荡管注-波互作用机理、高次谐波工作特性、谐波模式间竞争等关键特性。结果表明,通过调节磁场强度,可以在多个相邻谐波处连续激发振荡,实现频率为240 GHz到460 GHz之间的太赫兹波辐射,最大辐射功率为19kW。同时研究了第7、8和9次谐波模式之间的竞争,讨论了实现稳定注-波互作用和高次谐波状态下单模工作的方法。此外,论文还对不同谐波状态下的欧姆损耗功率进行了研究。 展开更多
关键词 大回旋电子注 回旋管 高次谐波 太赫兹
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基于激光雷达和摄像头的FSAC赛车锥桶感知算法研究 被引量:5
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作者 王华东 李刚 +1 位作者 李晓纲 张东 《河北科技大学学报》 CAS 北大核心 2022年第6期613-623,共11页
针对赛场环境下无人驾驶方程式赛车感知系统中锥桶检测准确率较低的问题,提出了一种基于激光雷达和摄像头标定融合的锥桶检测算法。首先,对激光雷达采集的点云进行滤波、地平面滤除、欧式聚类,得到感兴趣区域内锥桶的空间位置信息;其次... 针对赛场环境下无人驾驶方程式赛车感知系统中锥桶检测准确率较低的问题,提出了一种基于激光雷达和摄像头标定融合的锥桶检测算法。首先,对激光雷达采集的点云进行滤波、地平面滤除、欧式聚类,得到感兴趣区域内锥桶的空间位置信息;其次,通过标定后得到的摄像头的内外参矩阵将锥桶空间位置信息投影到像素平面内,并在HSV颜色空间下对锥桶空间位置周围一定区域内H通道的像素点进行颜色判断,从而获得锥桶的颜色信息;最后,将得到的锥桶颜色信息附加在锥桶的空间位置上以实现信息融合,在校园内模仿赛场环境进行实验验证。结果表明,标定融合算法能够满足赛场上不同项目的比赛要求,避免了使用单一传感器算法时出现对锥桶漏检误检的情况。因此,标定融合算法可实现对锥桶的有效检测,丰富了检测目标的信息,提高了检测锥桶的准确性,为方程式大赛中使用传感器融合进行锥桶检测提供了参考。 展开更多
关键词 车辆工程 无人驾驶方程式赛车 激光雷达 摄像头 时空对准 标定融合
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FSAC赛车动态视野算法研究 被引量:7
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作者 宫彦乔 刘立东 +1 位作者 李刚 张东 《重庆理工大学学报(自然科学)》 CAS 北大核心 2023年第1期1-8,共8页
针对中国大学生无人驾驶方程式(FSAC)赛车在高速转弯工况中,由于弯道视野中获得的桩桶数量少而易于导致路径规划失败的问题,设计了一种基于激光雷达和惯性导航的动态视野算法。该算法基于激光雷达信息对桩桶进行检测,同时利用惯性导航... 针对中国大学生无人驾驶方程式(FSAC)赛车在高速转弯工况中,由于弯道视野中获得的桩桶数量少而易于导致路径规划失败的问题,设计了一种基于激光雷达和惯性导航的动态视野算法。该算法基于激光雷达信息对桩桶进行检测,同时利用惯性导航解算得到航向角的变化量,并进行加权滑动平均滤波,预测下一时刻航向角变化趋势,结合车速与车轮转角信息,计算并调整感兴趣区域的范围,将感知视野保持在赛道中央,在转弯处获取更多桩桶信息。将算法进行实车验证,结果表明:有效提高了赛车的感知效率,提升了赛车的路径规划能力。 展开更多
关键词 FSAC赛车 激光雷达 惯性导航 动态视野 加权滑动平均滤波
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