Regeneration Potential of Woody Species at the Side of Secondary Roads Post-Logging of Loundoungou-Toukoulaka Forest Management Unit, Republic of the Congo

Natural regeneration is the basis of a dynamic and demographic balance of plant populations. The objective of this study was to assess the natural regeneration potential of woody species along secondary roads post-logging abandoned since 2008 and 2018. In the two Annual Allowable Cuts (AAC 2008 and AAC 2018), 24 regenerating sub-plots (i.e. 12 sub-plots for AAC 2008 and 12 sub-plots for AAC 2018) with a unit area of 5 m × 5 m were delimited with a total area of 0.06 ha (i.e. 0.03 ha for each AAC). The abundance and diversity of woody species were respectively inventoried and estimated. Two estimators of the specific richness were used to estimate the floristic diversity of each Annual Allowable Cuts (AAC). The results reveal globally 88 woody species in the AAC 2008 and 241 woody species in the AAC 2018, with respective average densities of 2933 stem/ha and 8033 stem/ha. There was a very highly significant difference between the mean densities of the two AAC (Kruskal-Wallis test;H = 2.36, p-value < 0.000). The results also highlight a great diversity and a relatively high abundance of woody species in the 2018 AAC compared to the 2008 AAC. Also, the spatial structuring of the sub-plots on the basis of Principal Component Analysis (PCA) demonstrates that the floristic composition of the two AAC is globally different. The study suggests silvicultural interventions and the long-term assessment of regenerating woody species along abandoned secondary roads in order to guarantee the sustainable management of their population.

Mapping regional forest management units:a road-based framework in Southeastern Coastal Plain and Piedmont

Management practices are one of the most important factors affecting forest structure and function.Landowners in southern United States manage forests using appropriately sized areas,to meet management objectives that include economic return,sustainability,and esthetic enjoyment.Road networks spatially designate the socioenvironmental elements for the forests,which represented and aggregated as forest management units.Road networks are widely used for managing forests by setting logging roads and firebreaks.We propose that common types of forest management are practiced in road-delineated units that can be determined by remote sensing satellite imagery coupled with crowd-sourced road network datasets.Satellite sensors do not always capture roadcaused canopy openings,so it is difficult to delineate ecologically relevant units based only on satellite data.By integrating citizen-based road networks with the National Land Cover Database,we mapped road-delineated management units across the regional landscape and analyzed the size frequency distribution of management units.We found the road-delineated units smaller than 0.5 ha comprised 64%of the number of units,but only0.98%of the total forest area.We also applied a statistical similarity test(Warren's Index)to access the equivalency of road-delineated units with forest disturbances by simulating a serious of neutral landscapes.The outputs showed that the whole southeastern U.S.has the probability of road-delineated unit of 0.44 and production forests overlapped significantly with disturbance areas with an average probability of 0.50.

Ruppert's Delaunay Triangulation Refinement Scheme for Optimal RSUs Placement in Vehicle to Infrastructure Communication Network

Road Side Units(RSUs)are the essential component of vehicular communication for the objective of improving safety and mobility in the road transportation.RSUs are generally deployed at the roadside and more specifically at the intersections in order to collect traffic information from the vehicles and disseminate alarms and messages in emergency situations to the neighborhood vehicles cooperating with the network.However,the development of a predominant RSUs placement algorithm for ensuring competent communication in VANETs is a challenging issue due to the hindrance of obstacles like water bodies,trees and buildings.In this paper,Ruppert’s Delaunay Triangulation Refinement Scheme(RDTRS)for optimal RSUs placement is proposed for accurately estimating the optimal number of RSUs that has the possibility of enhancing the area of coverage during data communication.This RDTRS is proposed by considering the maximum number of factors such as global coverage,intersection popularity,vehicle density and obstacles present in the map for optimal RSUs placement,which is considered as the core improvement over the existing RSUs optimal placement strategies.It is contributed for deploying requisite RSUs with essential transmission range for maximal coverage in the convex map such that each position of the map could be effectively covered by at least one RSU in the presence of obstacles.The simulation experiments of the proposed RDTRS are conducted with complex road traffic environments.The results of this proposed RDTRS confirmed its predominance in reducing the end-to-end delay by 21.32%,packet loss by 9.38%with improved packet delivery rate of 10.68%,compared to the benchmarked schemes.

Research on the Coverage of the Belt and Road Initiative and a Community with Shared Future for Mankind by Mainstream Media in the United States--Taking the three major mainstream media in the United States as an example

Since China put forward the Belt and Road Initiative and a community with shared future for mankind,mainstream media in the United States such as The Washington Post,The New York Times and The Wall Street Journal have given continuous reports.As the world’s superpower,the United States has a developed media system and a wide range of influence.The study extracted 173 valid texts from May 2015 to March 2020,among which only 5 reports were on a community with shared future for mankind.American media mainly reported from five aspects including economy,politics,cultural,security and environment,although there is no lack of certain sounds,there was more negative reports.It can provide a reference basis for our accurate response and creating a positive international public opinion environment that grasping the reporting trends on the Belt and Road Initiative and a community with shared future for mankind accurately.

A New System for Road Traffic Optimisation Using the Virtual Traffic Light Technology

Large cities suffer from traffic congestion,particularly at intersections,due to a large number of vehicles,which leads to the loss of time by increasing carbon emissions,including fuel consumption.Therefore,the need for optimising the flow of vehicles at different intersections and reducing the waiting time is a critical challenge.Conventional traffic lights have been used to control traffic flow at different intersections and have been improved to become more efficient by using different algorithms,sensors and cameras.However,they also face some challenges,such as high-cost installation,operation,and maintenance issues.This paper develops a new system based on the Virtual Traffic Light(VTL)technology to improve traffic flow at different intersections and reduce the encountered loss of time and vehicles’travel time.Additionally,it reduces the costs of installation,maintenance and operation over various conventional traffic light systems.Consequently,the system proposes algorithms for traffic scheduling and lane identification by using vehicle ID,priority and time of arrival.To evaluate the system,four scenarios were presented where each scenario uses a different number of vehicles consisting of three types(emergency vehicles,public buses and private vehicles),each given a different priority.The proposed system is evaluated by integrating two simulators,namely,(OMNeT++)and(SUMO),and two frameworks,namely,(VEINS)and(INET)to prepare an appropriate working environment.the results prove that an improvement in the average travel time for several vehicles reaches 44.43%–49.76%compared with conventional traffic lights.Further,it is proven from the obtained results that the average waiting time for emergency vehicles is enhanced by 96.63%–97.63%,while the average waiting time for public buses is improved by 94.81%–97.23%.On the other hand,the waiting time for private vehicles‘improved by 87.14%to 89.71%’.

基于RSU辅助的车载机会网络通信能力增强方案

针对传统车载机会网络通信能力的有限性及随机化的问题,提出一种通过部署路边单元(RSU)进行辅助通信来增强车载机会网络通信能力的方案。该方案利用RSU稳定的覆盖、存储和传输优势,有效克服传统车载机会网络通信时间间隔长、传输能力有限等缺点。以北京和上海各自一个月的出租车全球定位系统(GPS)数据为基础,对车辆与RSU的相遇特性进行了分析,发现该方案通过合理部署RSU对车辆信息进行缓存,可以极大地提高车辆间的通信概率。理论分析和仿真实验表明,利用RSU可以完成车与车之间大数据的传输,能极大提升车载机会网络的通信能力。

基于流量的车载网络路边单元RSU部署方案

针对目前车载移动容迟网络中的路边单元(RSU)部署问题,提出一种基于车流量的车载网络路边单元RSU部署方案,该方案通过对车载网中路口的车流量的统计行为进行分析,在城市重要交通枢纽和交叉路口部署路边单元RSU来进行辅助通信,从而有效提高车载移动网络的通信效率。根据北京和上海两地实际的车载移动数据,进一步对所提方案进行分析和评估。研究结果表明:在辅助车辆与车载之间的通信时,密集部署RSU可以创造连续的通信机会,从而有效提高网络性能。

基于多传感器融合技术的智慧路侧单元设计

基于多传感器融合技术,设计了一种智慧路侧单元。通过二维视觉感知和三维点云感知设计获取优质的交通信息;并在此基础上,完成点云和视觉的决策级融合。该智慧路侧单元可满足智慧交通领域实时路况检测需求,为车路协同的实现提供了切实可行的参考方案。

路网环境下基于Unit模型的位置隐私保护方法

基于位置的服务(LBS)为人们的日常生活带来很大便利,然而由此引起的用户隐私泄露问题也同样受到人们的关注.用户向LBS提交查询时必须提供确切位置信息,攻击者可根据用户的位置信息推断出该用户的私人信息进而做出一些违背道德法律的事情.为解决这个问题,现有的大部分空间匿名技术将用户的位置进行泛化,然后再发送到LBS服务器.本文基于路网环境提出一种新的路网模型,并以该路网模型提出一种新的路网匿名方法.首先,针对路网环境提出Unit路网模型,将道路网络划分为小的匿名单元,然后对匿名单元采用希尔伯特编码进行排序,为后面产生匿名区域和匿名区域扩展打下基础.其次,提出基于Unit路网模型的位置隐私保护算法.为保证服务质量,匿名区域的总长度不能超过一定的长度限制.因此在扩展匿名区域的时候只考虑有活跃用户的匿名单元.第三,提出在匿名区域内添加假用户的方法来提高匿名成功率.最后,基于理论分析和实验验证,证明了上述算法的有效性.

车载自组织网络中RSU协调的多信道MAC协议

提出了一种车载自组织网络中路侧单元(RSU, road side unit)协调的多信道MAC(RMM, RSU-coordinated multichannel MAC)协议,以支持非安全(如运输效率、娱乐应用等)消息的高效传输。在路侧单元的协调下,节点有更多机会在控制信道上进行预约,以实现服务信道上无竞争的传输。同时,RMM协议支持在整个同步间隔内传输服务分组,从而提高了服务信道的饱和吞吐量和利用率,并减少了时延。与现有的其他协议相比,仿真结果证实了所提协议的优越性。

车联网中RSU动态接入选择问题的研究

车联网中车与车以及车与基础设施间的实时通信问题越来越受到关注,而车辆的高速移动性和无线通信的不可靠性大大降低了数据传输效率。为了解决这个问题,针对路边单元(Road Side Unit, RSU)接入选择问题进行了研究,并提出了一种新的RSU接入选择算法,来合理调配车辆与RSU的连接。车辆选择RSU进行接入的常规方法是基于车辆的接收信号强度,但它未充分考虑车辆的高速移动性,这会导致接入RSU的车辆的数目大幅度变化。所以采用实时监测和预测相结合的方法合理调配RSU上连接的车辆,让每一RSU上连接的车辆数目波动幅度达到最小,并且保证RSU得到充分利用。仿真结果表明,此算法能够有效降低数据包碰撞、增强无碰撞传输概率、提高成功传包率。

基于C-V2X的智能路侧单元系统设计

随着自动驾驶技术和智能交通产业的不断发展,车路协同技术逐渐成为交通领域研究的热点,路侧单元RSU做为车路协同系统的路侧核心设备,是支撑车路协同技术应用的关键所在。基于此,文章设计了一种基于C-V2X的智能路侧单元,具备C-V2X直连通信及5G通信功能,支持C-V2X系列标准协议,能够连接路侧各类智能设备以及交通参与者,将路侧信息分析处理后上传到云端,同时将信息发送给车端,为智能网联车辆、自动驾驶车辆提供各类信息服务,支撑车路协同场景应用。

通信感知算力一体化在车联网中的应用探讨

移动通信、边缘计算、人工智能等技术的演进和规模化部署促进了车辆、交通、电子信息产业的深度融合,加速了单车智能化、高级别自动驾驶和车路云一体化的进展。蜂窝车联网通过无处不在的无线基站和边缘计算为车路云一体化提供更智能、更高效的信息感知、处理和信息交互能力,以此形成的通信感知算力一体化技术逐渐成为学术界和产业界关注的焦点。首先对蜂窝车联网和通信感知算力一体化技术进行了概述并分析了感知、定位、成像、辅助通信、自组网、边缘计算技术等关键技术点,进而列举了五种蜂窝车联网的典型场景案例,最后对未来蜂窝车联网产业化发展进行了展望,为车路云一体化的发展提供了重要思路。

“双碳”目标下浙江省道路运输业碳排放预测

为明确浙江省道路运输业的碳排放发展趋势,量化碳减排措施效果,通过分析浙江省道路运输行业车辆(公路客运、公路货运、公共汽车、出租汽车)的能源消耗与运输生产数据,提出单位碳排放强度指标,结合情景分析法构建基于单位碳排放强度的道路运输碳排放预测模型。结果表明,2021年浙江省公路客运、公路货运、公共汽车、出租汽车的单位碳排放强度分别为304.4 kg·(万人·km)^(-1)、383.3 kg·(万t·km)^(-1)、43.4 kg·(102km)^(-1)、12.5 kg·(102km)^(-1);不同情景下碳达峰时间不同,强化低碳情景下道路运输行业预测最早于2028年达峰,峰值为1490.2万t。新能源车推广发展、车辆运输能效提升以及运输结构调整,可有效降低道路运输业碳排放,加快实现道路运输业碳达峰。

论红西路军在永昌的统一战线工作

红西路军转战永昌期间,广泛宣传抗日民族统一战线的政治主张,动员社会各界进步力量,建立县级苏维埃政权,推进抗日运动,做了许多富有成效的工作。红西路军永昌统战工作产生的具体成效:(一)组织支前,为部队补充给养;(二)极力救援离散东返的西路军人员;(三)主动安葬、祭奠革命烈士。红西路军永昌统战工作的历史意义:播撒了中国革命的火种;树立了军民团结的典范,增进了永昌人民对党和红西路军的感情;推动了抗日民族统一战线的形成。

VANET中基于模糊逻辑的RSU自适应数据更新方案

在基于路边基站(RSU)的车载自组网(VANET)路由协议中,RSU以固定周期更新数据导致交通控制中心(TCC)的部分数据容易失效,造成数据包丢失,严重影响路由协议性能。为此,提出一种基于模糊逻辑的RSU自适应数据更新周期计算方案。RSU根据自身服务范围内车辆节点的运动状况,利用注册表中数据量和数据更新速率参数,设计模糊逻辑控制系统,自适应计算数据更新周期,从而提高TCC中数据的有效性。实验结果表明,与BUS-VANET路由协议相比,基于该方案的VANET路由协议能够提升通信链路的稳定性和可靠性,并降低数据更新包数量和传输时延。

基于双重防护理念的上跨线桥中墩防护设计

该文总结分析上跨线桥中墩位置的碰撞事故类型,发现防正碰和防剐蹭是桥墩防护的两项重要需求。基于此提出了双重防护新理念及对应技术方案。第一重防护通过在桥墩外围设置混凝土护栏或船形加高构件,以防止车辆正碰桥墩;第二重防护为桥墩自体通过包裹钢板或泡沫铝板以防止车辆剐蹭桥墩。通过计算机仿真和单元试验验证桥墩防护结构方案的安全性,评估其在防正碰和防剐蹭的双重作用。结果表明:该研究提出的设计方案能有效地保护人、车、桥的安全,降低事故严重程度及损失,有助于桥墩后期维护及耐久性保障,已在实际工程中得到应用与认可。

车联网中基于休眠机制部署RSUs方案

针对车联网(vehicular ad hoc networks,VANETs)中路边设施单元(road side units,RSUs)部署问题,提出部署RSU的新方案,记为P_RSU方案。P_RSU方案以保证必要的数据包传输率(packet delivery ratio,PDR)为前提,以降低所有RSUs消耗总能量为目的。P_RSU方案引用休眠机制,并采用太阳能作为RSUs能量供给的补充。首先将P_RSU方案进行形式化表述,形成约束条件、多目标函数。然后,通过RPR(rainbow product ranking)算法求解目标函数,从而获取部署RSUs的最优位置。仿真结果表明,提出的P_RSU方案能有效地降低能量消耗、优化RSUs数量。

抵抗推理攻击的车联网位置隐私增强方法

车联网中实体可信度不明确,用户与其他实体频繁通信,会增加用户隐私泄露风险。为此,提出一种抵抗推理攻击的车联网位置隐私增强方法。用户向路边单元(RSU)请求兴趣点(POIs),并从本地缓存中根据用户相似度推荐多个合适的POIs,在多POIs中选择最终目的地。即使兴趣点被攻击者窃取也难以推断用户的最终目的地。如果用户未收到期望的POI,可以向服务提供商(SP)请求扩大服务范围。仿真结果表明,与对比方法相比,所提方法的通信开销平均降低14%,位置熵平均提高12%。所提方案通过减小与SP的通信次数,不仅能减小通信开销,还能增强隐私保护程度。通过用户偏好计算更符合用户期望的多个POIs,供用户选择最终的目的地,不仅能提高服务可用性,还能抵抗推理攻击。

RSU辅助的V-NDN数据转发机制

V-NDN(vehicular named data networking)是一种使用命名数据网络架构的车辆自组织网络(vehicular Ad-hoc network,VANET),主要用来连接移动车辆之间的通信。提高网络中兴趣包的命中率是研究领域急待解决的难题。文章研究了城市道路环境下V-NDN的数据转发策略,考虑到城市道路环境下路侧单元(road side unit,RSU)被均匀广泛部署的特点,提出了一种基于RSU辅助的V-NDN数据转发策略(RSU aided V-NDN)。通过实验仿真与传统的V-NDN和基于蜂窝网络辅助的V-NDN进行对比,结果表明该文提出的数据转发策略有效地提高了网络的服务质量(quality of service,QoS)。