A Blockchain-Based Efficient Cross-Domain Authentication Scheme for Internet of Vehicles

The Internet of Vehicles(IoV)is extensively deployed in outdoor and open environments to effectively address traffic efficiency and safety issues by connecting vehicles to the network.However,due to the open and variable nature of its network topology,vehicles frequently engage in cross-domain interactions.During such processes,directly uploading sensitive information to roadside units for interaction may expose it to malicious tampering or interception by attackers,thus compromising the security of the cross-domain authentication process.Additionally,IoV imposes high real-time requirements,and existing cross-domain authentication schemes for IoV often encounter efficiency issues.To mitigate these challenges,we propose CAIoV,a blockchain-based efficient cross-domain authentication scheme for IoV.This scheme comprehensively integrates technologies such as zero-knowledge proofs,smart contracts,and Merkle hash tree structures.It divides the cross-domain process into anonymous cross-domain authentication and safe cross-domain authentication phases to ensure efficiency while maintaining a balance between efficiency and security.Finally,we evaluate the performance of CAIoV.Experimental results demonstrate that our proposed scheme reduces computational overhead by approximately 20%,communication overhead by around 10%,and storage overhead by nearly 30%.

热消融治疗肺部亚实性结节专家共识(2021年版)

局部热消融技术在肺部结节治疗领域正处在起步与发展阶段,为了肺结节热消融治疗的临床实践和规范发展,由"中国医师协会肿瘤消融治疗技术专家组""中国医师协会介入医师分会肿瘤消融专业委员会""中国抗癌协会肿瘤消融治疗专业委员会""中国临床肿瘤学会消融专家委员会"组织多学科国内有关专家,讨论制定了"热消融治疗肺部亚实性结节专家共识(2021年版)"。主要内容包括:(1)肺部亚实性结节的临床评估;(2)热消融治疗肺部亚实性结节技术操作规程、适应证、禁忌证、疗效评价和相关并发症;(3)存在的问题和未来发展方向。

Elevation of basal lacustrine sediments along the mid-lower reaches of the Yangtze River and its implications for the reconstruction of Holocene water levels

The middle and lower reaches of the Yangtze River,a primary region for freshwater lakes in China,have undergone significant transformations throughout the Holocene.These changes,driven by factors such as sea-level rise,climate change,and human activities,have led to the progressive elevation of water levels in this area.As a result,a floodplain has emerged,characterized by the formation of numerous shallow lakes along the river course.However,the pattern of water-level changes in the main channel of the Yangtze River during the Holocene remains unclear.This gap in knowledge poses challenges for understanding sediment transport dynamics,the interactions between the river and its adjacent lakes,and the prevention and control of flood disasters in the Yangtze River basin.To shed light on these issues,our study compiled data on the surface elevation and water depth of 81 lakes in the mid-lower reaches of the Yangtze River basin.Additionally,we analyzed historical water-level records from the 1900s to the 1970s at eight gauging stations from Shashi to Jiangyin along the river’s main stream.Our findings reveal that,particularly along the Jingjiang section,the basal elevation of most lakes is lower than the Yangtze River’s water level during the dry season.Conversely,the water level of the main stream exceeds that of both the floodplain and the lakes enclosed by the Jingjiang embankment.In the tidal reach,especially within the Taihu Lake basin,the basal elevation of lakes typically falls below sea level.Meanwhile,lakes located along the section from Chenglingji to Wuhu exhibit basal elevations that correspond with the Yangtze River’s annual average and dry season water levels.Given the widespread presence of lakes along the middle and lower reaches of the Yangtze River,our study introduces a new proxy for reconstructing the mean water level of the mid-lower Yangtze River in the Holocene.By analyzing sediments from Nanyi Lake and Chenyao Lake in the lower Yangtze River,we attempted to reconstruct the water level of the Yangtze River’s main channel since 8 ka BP.

多级双向拉伸挤出系统在聚合物加工中的应用进展

以自主研发的分割-双向拉伸-叠加单元(LME)为核心,借助数学中的积分思想,通过串联一系列的LME,累积单个LME中双向拉伸/剪切力场作用效果,发明一套新型多级双向拉伸挤出系统(MBSE)。分析讨论MBSE构造及原理,介绍MBSE拉伸/剪切复合力场的实现及分布,从纯聚合物、聚合物/聚合物共混材料,聚合物/无机纳米粒子复合材料等物料体系着重讨论了MBSE的特点与优势。研究结果表明,相对于传统的基于单一剪切力场的挤出成型方法,MBSE中的双向拉伸/剪切复合力场,在调控分散相形态、调控聚合物晶体结构、促进纳米填分散及调控纳米填料粒子网络等方面具有突出的优势,在高分子及其复合材料的加工成型中具有广阔的应用前景。

流动场诱导成核剂TMC-300取向分布对聚乳酸性能的影响

聚乳酸(PLA)分子链呈半刚性,结晶速率缓慢导致PLA制品几乎都为非晶态或低结晶度态。制品的耐久性与韧性较差,极大地限制了其在工业领域的应用。文中首先添加高效有机成核剂TMC-300用以改善其结晶性能,研究了TMC-300含量对其成核效率的影响;随后利用多级拉伸复合应力场诱导TMC-300取向分布研究其对PLA结晶及力学性能的影响。结果表明,TMC-300在多级拉伸复合应力场的诱导下沿流动方向取向分布,继而诱导PLA片晶垂直其轴向方向生长,实现PLA片晶沿流动方向的高度取向。在PLA/1%TMC-300体系中,PLA的结晶度达到38%,拉伸强度及断裂伸长率分别达到了92 MPa与32%。

基于液态金属/聚硫橡胶构筑兼具导热与自修复功能可拉伸热界面材料

针对导热自修复复合材料存在的自修复性能-导热性能-力学性能难以平衡的问题,利用液态金属(LM)作为导热填料,通过界面设计使LM与基体之间形成动态可逆配位键,提升复合材料导热性能的同时兼顾材料的力学性能和自修复性能。文中通过主链上含有大量二硫键(S-S)且以硫醇为端基(-SH)的液态聚硫橡胶(PSR)与液态金属(LM)共混复合,利用LM赋予复合材料较高热导率,借助PSR分子中的动态二硫键(S-S)及LM与PSR之间形成的金属-巯基、金属-硫自由基可逆配位键赋予材料自修复性能。研究表明,当LM的体积分数为50%时,复合材料导热率可达0.70 W/(m·K),是纯基体的4.17倍,断裂伸长率仍然高达525%,在90℃自修复4 h时,断裂伸长率修复效率达到98.3%,实现了材料自修复性能-导热性能-力学性能的平衡。

Recent advances of Rh-based intermetallic nanomaterials for catalytic applications

Rhodium(Rh)has received widespread attention in fundamental catalytic research and numerous industrial catalytic applications.Compared to homogeneous catalysts,Rh-based nanomaterials as heterogeneous catalysts are much easier to separate and collect after usage,making them more suitable for commercial use.To this purpose,there has been a constant demand in constructing stable and highly active Rh-based nanomaterials.In contrast to Rh-based solid solutions with a random distribution of metallic atoms in the lattice,Rh-based intermetallic compounds(IMCs)with a fixed stoichiometric ratio and an ordered atomic arrangement can ensure the homogenous distribution of active sites and structural stability in the catalytic process.In this review,we concentrate on the fabrication of Rh-based IMCs for catalytic applications.Various synthetic methods and protocols for the controlled preparation of Rh-based IMC are illustrated.Meanwhile,the catalytic applications and corresponding catalytic mechanisms are discussed.In addition,personal perspectives about the remaining challenges and prospects in this field are provided.We believe this review will be useful in directing the development of Rh-based IMC catalysts for heterogeneous catalysis.

Graded interface engineering of 3D/2D halide perovskite solar cells through ultrathin(PEA)_(2)PbI_(4) nanosheets

2D halide perovskites have emerged as promising materials because of their stability and passivation effect in perovskite solar cells(PSCs).However,the introduction of bulky organic ammonium cations from 2D halide perovskites would decrease the device performance generally compared to the traditional 3D MAPbI_(3).Incorporation of ultrathin 2D halide perovskite nanosheets(NSs)with 3D MAPbI_(3)could address this issue.Herein,we re port a rationally designed PSCs with dimensional graded 3D/2D MAPbI_(3)/(PEA)_(2)PbI_(4)heterojunction,in which 2D(PEA)_(2)PbI_(4)NSs were synthesized and incorporated between 3D MAPbI_(3)and hole-transporting layer.Besides the significantly improved stability,a notable increasement in power conversion efficiency(PCE)of 20%was obtained for the 3D/2D perovskite solar cells due to the favourable band alignment among(PEA)_(2)PbI_(4)NSs and the other components.The graded structure of MAPbI_(3)/(PEA)_(2)PbI_(4)would upshift the energy level continuously,which enhances the hole extraction efficiency thus reduces the interface charge recombination,leading to the increasements of VOC from1.04 V to 1.07 V,Jsc from 21.81 mA/cm^(2) to 23.15 mA/cm^(2) and the fill factor from 67.89% to 74.78%,and therefore an overall PCE of 18.53%.

Bifurcations and Single Peak Solitary Wave Solutions of an Integrable NonlinearWave Equation

Dynamical system theory is applied to the integrable nonlinear wave equation ut±(u^(3)−u^(2))x+(u^(3))xxx=0.We obtain the single peak solitary wave solutions and compacton solutions of the equation.Regular compacton solution of the equation correspond to the case of wave speed c=0.In the case of c 6=0,we find smooth soliton solutions.The influence of parameters of the traveling wave solutions is explored by using the phase portrait analytical technique.Asymptotic analysis and numerical simulations are provided for these soliton solutions of the nonlinear wave equation.

Changes of vegetation in southern China

In order to reveal the changes of vegetation in southern China since the Last Glacial Maximum, we have established high-resolution time scales and palynological sequences of borehole profiles by drilling cores in some weak areas of the research to restore vegetation changes over the past 20,000 years on the basis of previous work. This paper gives the vegetation zoning maps of 18, 9 and 6 ka BP respectively in southern China, and describes the distribution characteristics of plants in different zones/subzones. The results show that the vegetation zonations around 18 ka BP were significantly different from that at present.It appeared in turn with Cold-temperate coniferous forest and alpine meadow steppe zone, and Temperate mixed coniferous and broad-leaved forest zone/warm temperate deciduous broad-leaved forest zone from northwest to southeast in the west, and Temperate mixed coniferous and broad-leaved forest zone, Warm temperate deciduous broad-leaved forest zone, and Northern subtropical mixed evergreen and deciduous broad-leaved forest zone from north to south in the central and east. The vegetation distribution around 9 ka BP changed distinctively. Except that the northwest part was located in Mountain temperate mixed coniferous and broad-leaved forest zone, the vegetation in other areas occurred in turn with North subtropical mixed evergreen and deciduous broad-leaved forest subzone, Mid-subtropical typical evergreen broad-leaved forest subzone, and South subtropical monsoon evergreen broad-leaved forest subzone/Tropical seasonal rainforest and rainforest zone from north to south.There was little change in the appearance of vegetation zonations between 6 and 9 ka BP, but the northern edge of each vegetation belt moved a little northward, reflecting that the overall climate became warmer around 6 ka BP. The vegetation changes in southern China over the past 20,000 years were largely driven by environmental changes. Climate change was the main factor affecting the vegetation distribution. The impact of human activities became more and more remarkable in the later period. In the lower reaches of the Yangtze River and the delta region, sea level changes also influenced the vegetation distribution.

An aggregate flow based scheduler in multi-task cooperated UAVs network

Unmanned Aerial Vehicles(UAVs)cooperative multi-task system has become the research focus in recent years.However,the existing network frameworks of UAVs are not flexible and efficient enough to deal with the complex multi-task scheduling,because they are not able to perceive the different features.In this paper,a novel cooperated UAVs network framework for multi-task scheduling is proposed.It is a three-layer network including a core layer,an aggregation layer and an execution layer,which enhances the efficiency of multi-task distribution,aggregation and transmission.Furthermore,an Aggre Gate Flow(AGFlow)based scheduler is dedicatedly designed to maximize the task completion rate,whose key point is to aggregate flows belonging to one task during the multi-task transmission of UAVs network and to allocate priority by calculating the urgency-level of each AGFlow.Simulation results demonstrate that,compared with that of state-of-the-art scheduler,the average task completion rate of AGFlow based scheduler is raised by 0.278.