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Application of Connected Truck Data to Evaluate Spatiotemporal Impact of Rest Area Closures on Ramp Parking
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作者 Jijo K. Mathew Jairaj Desai +1 位作者 Edward D. Cox Darcy M. Bullock 《Journal of Transportation Technologies》 2024年第3期289-307,共19页
Ensuring adequate access to truck parking is critical to the safe and efficient movement of freight traffic. There are strict federal guidelines for commercial truck driver rest periods. Rest areas and private truck s... Ensuring adequate access to truck parking is critical to the safe and efficient movement of freight traffic. There are strict federal guidelines for commercial truck driver rest periods. Rest areas and private truck stops are the only places for the trucks to stop legally and safely. In locations without sufficient parking areas, trucks often park on interstate ramps, which create safety risks for other interstate motorists. Historically, agencies have employed costly and time intensive manual counting methods, camera surveillance, and driver surveys to assess truck parking. Connected truck data, available in near real-time, offers an efficient alternative to practitioners to assess truck parking patterns and identify areas where there may be insufficient safe parking spaces. This paper presents a case study of interstate I-70 in east central Indiana and documents the observed spatiotemporal impacts of a rest area closure on truck parking on nearby interstate ramps. Results showed that there was a 28% increase in parking on ramps during the rest area closure. Analysis also found that ramps closest to the rest area were most impacted by the closure, seeing a rise in truck parking sessions as high as 2.7 times. Parking duration on the ramps during rest area closure also increased drastically. Although it was expected that this would result in increased parking by trucks on adjacent ramps, this before, during, after scenario provided an ideal scenario to evaluate the robustness of these techniques to assess changing parking characteristics of long-haul commercial trucks. The data analytics and visualization tools presented in this study are scalable nationwide and will aid stakeholders in informed data-driven decision making when allocating resources towards improving the nations commercial vehicle parking infrastructure. 展开更多
关键词 connected Truck Data Rest areas Exit Ramps Truck Parking Commercial Vehicles
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Transport Accessibility and Spatial Connections of Cities in the Guangdong-Hong Kong-Macao Greater Bay Area 被引量:8
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作者 CAO Xiaoshu OUYANG Shishu +3 位作者 YANG Wenyue LUO Yi LI Baochao LIU Dan 《Chinese Geographical Science》 SCIE CSCD 2019年第5期820-833,共14页
Based on geographic information system(GIS) spatial analysis technology, the spatial pattern of raster grid transport accessibility for the Guangdong-Hong Kong-Macao Greater Bay area was studied and the states of spat... Based on geographic information system(GIS) spatial analysis technology, the spatial pattern of raster grid transport accessibility for the Guangdong-Hong Kong-Macao Greater Bay area was studied and the states of spatial connectedness were simulated using highway passenger transport, railway passenger transport, port passenger transport and aviation passenger transport data. The result shows that transport accessibility within the Guangdong-Hong Kong-Macao Greater Bay area costs ‘one hour’ and the spatial distribution of accessibility in the area presents clear ‘core-periphery’ spatial characteristics, with Guangzhou, Foshan, Shenzhen constituting the core. The transport accessibility of Guangdong-Hong Kong-Macao is high. Average accessibility of urban nodes as measured by travel time is 0.99 h, and the areas accessible within 1.42 h occupy 79.14% of the total area. Most of the areas with the lowest accessibility are found in the peripheral area, with the worst accessibility being 4.73 h. Compared with the west-side cities, the economically developed east-side cities of the Guangdong-Hong Kong-Macao Greater Bay area have higher connectivity with roads, railways, ports, and aviation transport. Guangzhou, Foshan, Zhuhai, Shenzhen, Hong Kong and Macao are closely linked. The higher the accessibility, the closer the intercity connectedness. 展开更多
关键词 transport ACCESSIBILITY urban SPATIAL connection Guangdong-Hong Kong-Macao GREATER BAY area China
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Changes in brain functional network connectivity after stroke 被引量:3
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作者 Wei Li Yapeng Li +1 位作者 Wenzhen Zhu Xi Chen 《Neural Regeneration Research》 SCIE CAS CSCD 2014年第1期51-60,共10页
Studies have shown that functional network connection models can be used to study brain net- work changes in patients with schizophrenia. In this study, we inferred that these models could also be used to explore func... Studies have shown that functional network connection models can be used to study brain net- work changes in patients with schizophrenia. In this study, we inferred that these models could also be used to explore functional network connectivity changes in stroke patients. We used independent component analysis to find the motor areas of stroke patients, which is a novel way to determine these areas. In this study, we collected functional magnetic resonance imaging datasets from healthy controls and right-handed stroke patients following their first ever stroke. Using independent component analysis, six spatially independent components highly correlat- ed to the experimental paradigm were extracted. Then, the functional network connectivity of both patients and controls was established to observe the differences between them. The results showed that there were 11 connections in the model in the stroke patients, while there were only four connections in the healthy controls. Further analysis found that some damaged connections may be compensated for by new indirect connections or circuits produced after stroke. These connections may have a direct correlation with the degree of stroke rehabilitation. Our findings suggest that functional network connectivity in stroke patients is more complex than that in hea- lthy controls, and that there is a compensation loop in the functional network following stroke. This implies that functional network reorganization plays a very important role in the process of rehabilitation after stroke. 展开更多
关键词 nerve regeneration brain injury STROKE motor areas functional magnetic resonanceimaging brain network independent component analysis functional network connectivity neuralplasticity NSFC grant neural regeneration
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Filtering bleb area and intraocular pressure following subconjunctival injection of CTGF antibody after glaucoma filtration surgery in rabbits 被引量:2
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作者 Jian-Ming Wang Na Hui +2 位作者 Ya-Zhi Fan Lei Xiong and Nai-Xue Sun 《International Journal of Ophthalmology(English edition)》 SCIE CAS 2011年第5期480-483,共4页
AIM: To study the role of connective tissue growth factor (CTGF) antibody in inhibiting bleb scarring after glaucoma filtration surgery (GFS) in rabbit model. METHODS: GFS was performed on both eyes in five rabbits. O... AIM: To study the role of connective tissue growth factor (CTGF) antibody in inhibiting bleb scarring after glaucoma filtration surgery (GFS) in rabbit model. METHODS: GFS was performed on both eyes in five rabbits. One eye of each rabbit was chosen randomly as antibody group and received subconjunctival injection of 0.1mL CTGF antibody (50mg/L) immediately after GFS applied and on the 5 th day after GFS. The other eye of each rabbit as control group was received subconjunctival injection of 0.1mL PBS at the same time as antibody group. On postoperative days 1, 3, 5, 7, 10, and 14, the appearance of filtrating blebs was observed under slit lamp, the area and the intraocular pressure (IOP) were measured with micrometer and applanation tonometer, respectively. RESULTS: On postoperative days 1, 3, 5, 7, 10, and 14, areas of filtrating blebs in antibody group were all larger comparing with the control group (P<0.05) and IOPs of antibody group were lower than the control group(P<0.05). CONCLUSION: Subconjunctival injection of CTGF antibody can maintain larger bleb area and lower IOP after GFS in rabbit. 展开更多
关键词 connective tissue growth factor antibody TRABECULECTOMY area of filtrating bleb intraocular pressure
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Non-concomitant cortical structural and functional alterations in sensorimotor areas following incomplete spinal cord injury 被引量:2
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作者 Yu Pan Wei-bei Dou +9 位作者 Yue-heng Wang Hui-wen Luo Yun-xiang Ge Shu-yu Yan Quan Xu Yuan-yuan Tu Yan-qing Xiao Qiong Wu Zhuo-zhao Zheng Hong-liang Zhao 《Neural Regeneration Research》 SCIE CAS CSCD 2017年第12期2059-2066,共8页
Brain plasticity, including anatomical changes and functional reorganization, is the physiological basis of functional recovery after spinal cord injury(SCI). The correlation between brain anatomical changes and fun... Brain plasticity, including anatomical changes and functional reorganization, is the physiological basis of functional recovery after spinal cord injury(SCI). The correlation between brain anatomical changes and functional reorganization after SCI is unclear. This study aimed to explore whether alterations of cortical structure and network function are concomitant in sensorimotor areas after incomplete SCI. Eighteen patients with incomplete SCI(mean age 40.94 ± 14.10 years old; male:female, 7:11) and 18 healthy subjects(37.33 ± 11.79 years old; male:female, 7:11) were studied by resting state functional magnetic resonance imaging. Gray matter volume(GMV) and functional connectivity were used to evaluate cortical structure and network function, respectively. There was no significant alteration of GMV in sensorimotor areas in patients with incomplete SCI compared with healthy subjects. Intra-hemispheric functional connectivity between left primary somatosensory cortex(BA1) and left primary motor cortex(BA4), and left BA1 and left somatosensory association cortex(BA5) was decreased, as well as inter-hemispheric functional connectivity between left BA1 and right BA4, left BA1 and right BA5, and left BA4 and right BA5 in patients with SCI. Functional connectivity between both BA4 areas was also decreased. The decreased functional connectivity between the left BA1 and the right BA4 positively correlated with American Spinal Injury Association sensory score in SCI patients. The results indicate that alterations of cortical anatomical structure and network functional connectivity in sensorimotor areas were non-concomitant in patients with incomplete SCI, indicating the network functional changes in sensorimotor areas may not be dependent on anatomic structure. The strength of functional connectivity within sensorimotor areas could serve as a potential imaging biomarker for assessment and prediction of sensory function in patients with incomplete SCI. This trial was registered with the Chinese Clinical Trial Registry(registration number: Chi CTR-ROC-17013566). 展开更多
关键词 nerve regeneration incomplete spinal cord injury gray matter volume functional connectivity sensorimotor areas functionalmagnetic resonance imaging brain plasticity non-concomitant anatomical structure network imaging biomarker neural regeneration
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Migration and speciation transformation mechanisms of mercury in undercurrent zones of the Tongguan gold mining area, Shaanxi Loess Plateau and impact on the environment 被引量:5
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作者 Rui-ping Liu You-ning Xu +2 位作者 Hui-chao Rui El-Wardany RM Ying Dong 《China Geology》 2021年第2期311-328,共18页
In order to study the migration and transformation mechanism of Hg content and occurrence form in subsurface flow zone of gold mining area in Loess Plateau and its influence on water environment,the field in-situ infi... In order to study the migration and transformation mechanism of Hg content and occurrence form in subsurface flow zone of gold mining area in Loess Plateau and its influence on water environment,the field in-situ infiltration test and laboratory test were carried out in three typical sections of river-side loess,alluvial and proluvial strata in Tongguan gold mining area of Shaanxi Province,and the following results were obtained:(1)The source of Hg in subsurface flow zone is mainly caused by mineral processing activities;(2)the subsurface flow zone in the study area is in alkaline environment,and the residual state,iron and manganese oxidation state,strong organic state and humic acid state of mercury in loess are equally divided in dry and oxidizing environment;mercury in river alluvial or diluvial strata is mainly concentrated in silt,tailings and clayey silt soil layer,and mercury has certain stability,and the form of mercury in loess is easier to transform than the other two media;(3)under the flooding condition,most of mercury is trapped in the silt layer in the undercurrent zone where the sand and silt layers alternate with each other and the river water and groundwater are disjointed,and the migration capacity of mercury is far less than that of loess layer and alluvial layer with close hydraulic connection;(4)infiltration at the flood level accelerates the migration of pollutants to the ground;(5)the soil in the undercurrent zone is overloaded and has seriously exceeded the standard.Although the groundwater monitoring results are safe this time,relevant enterprises or departments should continue to pay attention to improving the gold extraction process,especially vigorously rectify the small workshops for illegal gold extraction and the substandard discharge of the three wastes,and intensify efforts to solve the geological environmental problems of mines left over from history.At present,the occurrence form of mercury in the undercurrent zone is relatively stable,but the water and soil layers have been polluted.The risk of disjointed groundwater pollution can not be ignored while giving priority to the treatment of loess and river alluvial landform areas with close hydraulic links.The research results will provide a scientific basis for water conservancy departments to groundwater prevention and control in water-deficient areas of the Loess Plateau. 展开更多
关键词 Mercury speciation Hyporheic zones Constant surface water level Flood level Surface-groundwater Hydraulic connection Tongguan gold mining areas Loess Plateau Shannxi Province
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An advanced segmentation using area and boundary tracing technique in extraction of lungs region
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作者 Kiran THAPALIYA Sang-Woong LEE +2 位作者 Jae-Young PYU Heon JEONG Goo-Rak KWON 《Journal of Central South University》 SCIE EI CAS 2014年第10期3811-3820,共10页
A new method is presented for the segmentation of pulmonary parenchyma. The proposed method is based on the area calculation of different objects in the image. The main purpose of the proposed algorithm is the segment... A new method is presented for the segmentation of pulmonary parenchyma. The proposed method is based on the area calculation of different objects in the image. The main purpose of the proposed algorithm is the segment of the lungs images from the computer tomography(CT) images. The original image is binarized using the bit-plane slicing technique and among the different images the best binarized image is chosen. After binarization, the labeling is done and the area of each label is calculated from which the next level of binarized image is obtained. Then, the boundary tracing algorithm is applied to get another level of binarized image. The proposed method is able to extract lung region from the original images. The experimental results show the significance of the proposed method. 展开更多
关键词 bit-plane slicing technique connected component labeling area tracing boundary tracing
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Investigating connectional characteristics of Motor Cortex network
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作者 Dong-Mei Hao Ming-Ai Li 《Journal of Biomedical Science and Engineering》 2009年第1期30-35,共6页
To understand the connectivity of cerebral cor-tex, especially the spatial and temporal pattern of movement, functional magnetic resonance imaging (fMRI) during subjects performing finger key presses was used to extra... To understand the connectivity of cerebral cor-tex, especially the spatial and temporal pattern of movement, functional magnetic resonance imaging (fMRI) during subjects performing finger key presses was used to extract functional networks and then investigated their character-istics. Motor cortex networks were constructed with activation areas obtained with statistical analysis as vertexes and correlation coefficients of fMRI time series as linking strength. The equivalent non-motor cortex networks were constructed with certain distance rules. The graphic and dynamical measures of motor cor-tex networks and non-motor cortex networks were calculated, which shows the motor cortex networks are more compact, having higher sta-tistical independence and integration than the non-motor cortex networks. It indicates the motor cortex networks are more appropriate for information diffusion. 展开更多
关键词 Motor CORTEX NETWORK connectIVITY Correlation COEFFICIENT Functional Magnetic RESONANCE Imaging (fMRI) Activation area
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Height connection across sea by using satellite altimetry data sets,ellipsoidal heights,astrogeodetic deflections of the vertical,and an Earth Gravity Model
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作者 Jianbo Wang Xinmin Qi +3 位作者 Kai Luo Zhengyuan Li Ruikang Zhou Jinyun Guo 《Geodesy and Geodynamics》 EI CSCD 2023年第4期347-354,共8页
Islands and the mainland are separated by seas,and the distances between them might be so long that the height on the mainland cannot be exactly translated to the islands,resulting in different height systems on the m... Islands and the mainland are separated by seas,and the distances between them might be so long that the height on the mainland cannot be exactly translated to the islands,resulting in different height systems on the mainland and the islands.In this study,we used astrogeodetic deflections of the vertical and ellipsoidal heights of points on the mainland and island near their coastlines to implement height connection across sea areas.First,the modeled gravity and modeled astrogeodetic vertical deflections of segmentation points along connecting routes over the sea between the mainland and the island were determined by Earth Gravity Model(EGM),and the ellipsoidal heights of segmentation points were determined by the satellite altimetry data sets.Second,we used a linear interpolation model to increase the precision of the vertical deflections of segmentation points.Third,we computed the geopotential difference of points between the mainland and the island using a method derived from geopotential theory and the astronomical leveling principle.Finally,we estimated the normal height of the point on the island using the geopotential-difference iterative computation approach.Using observed data of normal heights,ellipsoidal heights,and astrogeodetic vertical deflections referring to height sites in Qingdao,Shandong Province,we conducted a numerical experiment involving the normal height connection across sea regions.We determined the data of the ellipsoidal heights and gravity of segmentation points along the connecting route across the water in the numerical experiment using DTU10.The distance of the height connection across the sea was approximately 10.5 km.According to China's official leveling specifications,the experimental results met the criterion of third-class leveling precision. 展开更多
关键词 Height datum connection across sea areas Geopotential difference Normal heights Astrogeodetic vertical deflections ISLANDS
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Lobster Fishery Connectivity and Management In Indonesia Waters
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作者 Waluyo Taslim Arifin 《Journal of Fisheries Science》 2021年第1期1-7,共7页
The distribution of lobsters in Indonesian waters is very wide,even lobster species in Indonesia are also scattered in the tropical waters of the western Pacific Ocean,the Indian Ocean,Africa to Japanese waters.Indone... The distribution of lobsters in Indonesian waters is very wide,even lobster species in Indonesia are also scattered in the tropical waters of the western Pacific Ocean,the Indian Ocean,Africa to Japanese waters.Indonesian waters are divided into 11(eleven)Fishery Management Zone(FMZ).Lobsters in Indonesia may come from various water areas,both national and regional water zones,and they’re called the sink population.Its spread is influenced by the movement of the current.Lobster seed is nurtured by nature through ocean currents from Australia,East Indonesia,Japan,then back to Australia.Lobsters have a complex life cycle,where adult lobsters inhabit coral reefs as a place to lay eggs,then hatch into planktonic larvae,and grow up in open seas and carry out diurnal and ontogenetic vertical migrations before returning to nurseries in shallow coastal areas and reefs,coral,as well as habitat by the type of species.Literature research had used at least two methodologies to estimate the distribution and connection sensitivity matrices of marine organism larvae.The two most common approaches are using genetic markers and numerical biophysical modeling.Thus,this research uses molecular genetic techniques to explain the ge­netic structure of lobster populations using a biophysical model approach that can explain the genetic structure of lobsters,as well as the distribution based on regional oceanographic synthesis data and lobster biology known in Indonesian waters.This model has four components,namely:1)a ben­thic module based on a Geographical Information System(GIS)which is a lobster habitat in the spawning and recruitment process,2)a physical oceanography module containing daily velocity in the form of a three-di­mensional hydrodynamic model,3)a larva biology module that describes larval life history characteristics,and 4)a Lagrangian Stochastic module that tracks the individual trajectories of larvae. 展开更多
关键词 Lobster fishery Fishery management areas Lobster connectivity Biophysical mode
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How to use the PING to test network connection
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作者 ZHAO Zong-hui 《通讯和计算机(中英文版)》 2008年第2期62-64,共3页
关键词 PING 计算机技术 网络 连接速度
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连通设备粉尘爆炸泄压面积确定方法
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作者 李刚 周雷 +1 位作者 张晓宇 张凯 《东北大学学报(自然科学版)》 EI CAS CSCD 北大核心 2024年第2期276-281,共6页
国内外相关标准提供了单体设备的泄压面积计算方法,但连通设备的准则尚属空白.通过FLACS数值模拟,以玉米淀粉为爆炸介质,探究了连通设备内的泄爆压力和压力上升速率.结果表明:当管道长度一定时,传爆容器内最大泄爆压力随泄压面积增加而... 国内外相关标准提供了单体设备的泄压面积计算方法,但连通设备的准则尚属空白.通过FLACS数值模拟,以玉米淀粉为爆炸介质,探究了连通设备内的泄爆压力和压力上升速率.结果表明:当管道长度一定时,传爆容器内最大泄爆压力随泄压面积增加而降低;在设置相同泄压面积时,传爆容器内的最大泄爆压力随管道长度的增长而增大,且达到最大泄爆压力的时间也随之延后;传爆容器所需最小安全泄压面积大于同等大小单体设备的泄压面积,说明现有单体设备的泄压面积计算方法对于连通设备不适用.通过数值拟合,对标准中单体设备的泄压面积计算公式进行修正,使其满足连通设备安全泄压要求.研究结果为连通系统的防爆设计提供参考和依据. 展开更多
关键词 连通设备 粉尘爆炸 数值模拟 泄爆压力 泄压面积
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基于高速公路客流数据的重庆与毗邻地区联系网络空间结构研究
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作者 宗会明 刘绘敏 +2 位作者 陈易林 张大鹏 张嘉敏 《热带地理》 CSCD 北大核心 2024年第5期794-803,共10页
基于高速公路交通客流数据,采用社会网络与GIS空间分析法,以客流联系视角探讨重庆市与毗邻地区的城镇网络空间结构。结果表明:1)重庆中心城区为网络的绝对核心,长寿、江津、璧山为网络中的重要节点城市,涪陵、璧山、长寿在网络中通达性... 基于高速公路交通客流数据,采用社会网络与GIS空间分析法,以客流联系视角探讨重庆市与毗邻地区的城镇网络空间结构。结果表明:1)重庆中心城区为网络的绝对核心,长寿、江津、璧山为网络中的重要节点城市,涪陵、璧山、长寿在网络中通达性明显,涪陵、黔江、江津、万州的中介作用突出;2)重庆与毗邻地区的客流网络呈现三级轴线联系,整体网络呈现明显的放射性特征,部分地区联系突破省级行政边界,网络层级按照“4+15+18”分布;3)重庆与毗邻地区的凝聚子群表现出高度的地理邻近性,形成“核心―边缘”结构。未来重庆中心城区需进一步加强与四川东部地级市的辐射能力与交通联系,进一步培育与成都双城联系的发展轴,在远期发展中考虑纳入遵义市等地区更好融入重庆都市圈。 展开更多
关键词 网络结构 公路客流 都市圈联系 毗邻地区 重庆
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利用激光点云的智能网联汽车自主换道横向避障
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作者 白雪 赵宇 +2 位作者 温国强 王春絮 王伟 《激光杂志》 CAS 北大核心 2024年第6期238-242,共5页
通过智能网联汽车自主换道横向避障设计,提高车辆自主驾驶安全性能,提出基于激光点云的智能网联汽车自主换道横向避障方法,构建基于全激光雷达的无人驾驶系统的汽车行驶环境激光点云数据采集模型,通过激光雷达激光点云图像检测方法实现... 通过智能网联汽车自主换道横向避障设计,提高车辆自主驾驶安全性能,提出基于激光点云的智能网联汽车自主换道横向避障方法,构建基于全激光雷达的无人驾驶系统的汽车行驶环境激光点云数据采集模型,通过激光雷达激光点云图像检测方法实现对智能网汽车行驶环境感知。结合障碍物检测、车道线检测、可行驶区域检测的方法,分析智能网联下汽车换道障碍物和车道的相关性特征量,通过激光点云的自主寻优方法寻找边界点直到搜索路径达到阈值,再结合直线道路模型和车道线连续性原则实现对汽车自主换道横向避障规划设计。仿真结果表明,采用该方法进行汽车自主环控避障,在5 s时达到收敛状态,障碍物坐标识别误差距离低于0.7,并且该方法的识别精度达到了0.970以上,提高了车道信息的感知能力,准确高效地估计可行驶区域,提高车辆避障能力。 展开更多
关键词 激光点云 智能网联汽车 自主换道 横向避障 可行驶区域
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深化沈阳现代化都市圈一体化发展的挑战与对策
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作者 邹丽 吴琼 孙楚寒 《中国商论》 2024年第15期155-158,共4页
现代化都市圈一体化发展是城市和国家经济发展到一定阶段的必经之路,本文采用定量和定性分析相结合的方法,深入分析沈阳现代化都市圈一体化发展过程中面临着产业发展阶段存在差异、产业结构趋同、深层次产业分工协作较弱等问题,并根据... 现代化都市圈一体化发展是城市和国家经济发展到一定阶段的必经之路,本文采用定量和定性分析相结合的方法,深入分析沈阳现代化都市圈一体化发展过程中面临着产业发展阶段存在差异、产业结构趋同、深层次产业分工协作较弱等问题,并根据沈阳都市圈7市1区的实际状况,提出构建“1+ 2+ 6”式对策机制,围绕政务一体化、交通一体化和现代化、基础设施一体化、数字资源一体化、产业一体化和互补共生化、公共服务一体化和便利化等方面建立城市跨界发展与互通模式,重塑以沈阳为中心的辽宁经济发展格局,加快辽宁和东北经济发展。 展开更多
关键词 都市圈 一体化发展 “1+2+6”式 城市跨界与互通 高质量发展
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基于无滑移接触的螺栓连接结构动力学建模方法及试验验证
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作者 胡杰 鄂林仲阳 唐蔡平 《航天器环境工程》 CSCD 2024年第5期538-544,共7页
为准确描述和分析动力学环境下螺栓连接结构的响应行为,提出将无滑移接触区域作为有效接触区的螺栓连接结构动力学简化建模方法;无滑移接触区可通过非线性静力学数值模拟获得。仿真结果表明,螺栓预紧力对无滑移接触区范围影响甚微,可以... 为准确描述和分析动力学环境下螺栓连接结构的响应行为,提出将无滑移接触区域作为有效接触区的螺栓连接结构动力学简化建模方法;无滑移接触区可通过非线性静力学数值模拟获得。仿真结果表明,螺栓预紧力对无滑移接触区范围影响甚微,可以避免拧紧力矩以及拧紧力矩系数等参数的取值差异对建模精度的影响。同时,开展了典型组合结构从部件级到系统级的多层级模态试验,测试结果表明多阶模态频率及振型的试验结果与仿真结果吻合良好,说明该建模方法准确、有效,适用于正向设计过程中对产品动力学特性的研究。 展开更多
关键词 螺栓连接 无滑移接触区 动力学建模 数值仿真 模态试验
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基于图像内凹度的矿井外因火灾识别及抗干扰方法
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作者 孙继平 李小伟 《煤炭学报》 EI CAS CSCD 北大核心 2024年第7期3253-3264,共12页
尽早发现矿井火灾并处置,可避免或减少人员伤亡和财产损失及次生事故的发生。井下没有日光、月光、星光及闪电等自然光源,影响矿井火灾图像识别的主要是矿井光源。圆形度能够排除圆形光源的干扰,但难以排除非圆形光源的干扰。矩形度能... 尽早发现矿井火灾并处置,可避免或减少人员伤亡和财产损失及次生事故的发生。井下没有日光、月光、星光及闪电等自然光源,影响矿井火灾图像识别的主要是矿井光源。圆形度能够排除圆形光源的干扰,但难以排除非圆形光源的干扰。矩形度能够排除矩形光源的干扰,但难以排除非矩形光源的干扰。在工程实际中,因摄像机的拍摄角度不同,矿井光源图像会出现变形,无法呈现理想的规则形状,使用圆形度和矩形度算法难以排除矿井光源的干扰。揭示了火焰图像轮廓外接图面积明显大于其图像实际面积,圆形灯、长方形灯和正方形灯等矿井实际光源图像轮廓外接图面积近似等于其光源图像实际面积等特点。提出基于图像内凹度的矿井火灾识别及抗干扰方法,计算目标图像面积与图像轮廓外接图面积的比值(即图像内凹度),根据火焰图像内凹度数值较小,而矿井光源图像内凹度数值较大,区分火焰与矿井光源。提出的内凹度方法不受摄像机距检测目标距离和图像大小、摄像机安装位置和摄像机拍摄检测目标的角度、矿井光源形状等影响,适应性强,识别准确率高。实验表明,内凹度识别方法计算得到的矿井干扰光源减去火焰图像平均差值最大,波动最小,区分度最好,受摄像机拍摄角度及距离影响最小,抗干扰能力最强,准确率为91.6%。矩形度识别方法计算得到的矿井干扰光源减去火焰图像平均差值较大,波动较小,区分度较好,受摄像机拍摄角度及距离影响较小,抗干扰能力一般,准确率为72.5%。圆形度识别方法计算得到的矿井干扰光源减去火焰图像平均差值最小,波动最大,区分度最差,受摄像机拍摄距离影响较小,受摄像机拍摄角度影响大,抗干扰能力最差,准确率为12.0%。因此,提出的内凹度识别方法,优于矩形度和圆形度,区分度最好,受摄像机拍摄角度及距离影响最小,抗干扰能力最强。 展开更多
关键词 矿井火灾 图像内凹度 图像轮廓 外接图面积 火灾监测 图像识别
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机织钩面粘扣带表面质量的机器视觉检测方法
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作者 金守峰 李政 +2 位作者 徐畅 昝杰 郭彩霞 《毛纺科技》 CAS 北大核心 2024年第4期103-110,共8页
针对机织钩面粘扣带表面质量人工检测中存在的精度低等问题,提出了基于机器视觉的机织钩面粘扣带表面质量检测方法。通过单目视觉的切向成像获得粘扣带表面的单行图像,避免了粘扣带相邻行之间的干扰。对单行粘扣带图像进行预处理后,采... 针对机织钩面粘扣带表面质量人工检测中存在的精度低等问题,提出了基于机器视觉的机织钩面粘扣带表面质量检测方法。通过单目视觉的切向成像获得粘扣带表面的单行图像,避免了粘扣带相邻行之间的干扰。对单行粘扣带图像进行预处理后,采用投影法对其进行水平投影和垂直投影,提取粘扣带表面单行图像中的每个钩扣状区域,基于连通域统计法判别钩扣状区域的切割状态,计算其切开率,通过统计数据表征粘扣带表面质量。实验结果表明,该方法对机织钩面粘扣带表面质量的检测相对误差为1%,具有较高的稳定性。 展开更多
关键词 机织钩面粘扣带 切向成像 投影法 钩扣状区域 连通域
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基于直流电流瞬时微分的特高压直流分层接入系统非故障层换相失败预防控制策略
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作者 王渝红 李元琦 +2 位作者 廖建权 陈立维 赏成波 《电力自动化设备》 EI CSCD 北大核心 2024年第2期126-132,146,共8页
在特高压直流分层接入系统中,由于层间耦合作用,某一层交流系统发生故障可能导致非故障层换流器发生换相失败。为此,考虑到故障过程直流电流的变化,提出一种基于直流电流瞬时微分的换相失败预防控制策略。该策略基于故障后直流电流的变... 在特高压直流分层接入系统中,由于层间耦合作用,某一层交流系统发生故障可能导致非故障层换流器发生换相失败。为此,考虑到故障过程直流电流的变化,提出一种基于直流电流瞬时微分的换相失败预防控制策略。该策略基于故障后直流电流的变化特性,得到换相电流时间面积控制中触发角修正量,代替原有换相失败预防控制,提高非故障层换相失败预防控制的启动精度;同时基于电流预测量和等效直流输入电阻动态调整低压限流控制器的指令值,提高其响应速度。在PSCAD/EMTDC中搭建仿真模型对不同工况下所提控制策略进行验证。结果表明,该策略可降低高低端换流器同时发生换相失败的风险,改善故障后系统的运行性能。 展开更多
关键词 特高压直流输电 分层接入系统 换相失败 电流预测 换相电流时间面积 低压限流控制器
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考虑智能网联车辆影响的八车道高速公路施工区可变限速控制方法
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作者 过秀成 肖哲 +2 位作者 张一鸣 张叶平 许鹏宇 《东南大学学报(自然科学版)》 EI CAS CSCD 北大核心 2024年第2期353-359,共7页
为提升车联网环境下高速公路施工区交通运行效率及安全水平,提出了一种基于强化学习的可变限速控制方法.选取智能驾驶模型和真车试验模型,分别对传统人工车辆和智能网联车辆的跟驰行为进行建模,构建了以瓶颈下游路段交通流量为效率指标... 为提升车联网环境下高速公路施工区交通运行效率及安全水平,提出了一种基于强化学习的可变限速控制方法.选取智能驾驶模型和真车试验模型,分别对传统人工车辆和智能网联车辆的跟驰行为进行建模,构建了以瓶颈下游路段交通流量为效率指标、瓶颈路段速度标准差为安全指标的复合奖励值,利用深度确定性策略梯度算法,分车道动态求解最佳限速值.仿真结果表明,所提可变限速控制方法在不同智能网联车辆渗漏率条件下均能有效提升交通流运行效率和安全水平,且在智能网联车辆渗漏率较低时,提升效果更加显著.当智能网联车辆渗漏率为1.0时,瓶颈下游路段交通流量提升10.1%,瓶颈路段速度标准差均值下降68.9%;当智能网联车辆渗漏率为0时,瓶颈下游路段交通流量提升20.7%,瓶颈路段速度标准差均值下降78.1%.智能网联车辆的引入能够提升至多52.0%的瓶颈下游路段交通流量. 展开更多
关键词 可变限速控制 深度确定性策略梯度算法 八车道高速公路施工区 智能网联车辆 协同自适应巡航控制
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