绿色施工下的深路堑施工群综合承载度分析

为寻求最优化“绿色施工—资源—环境—施工活动强度”组合系统,基于理想承载状态下的多维效益,以施工群为研究主体,考虑工程施工中排污因子的短板效应,构建施工群承载机制的木桶模型. 采用状态空间法原理,取木桶模型的桶底、桶壁、桶中水作状态轴,以承载状况为研究对象,建立施工群承载度的状态空间模型. 结合深路堑施工工艺和专家决策意见遴选出31个变量作为承、压指标,基于Canopy平台,运用随机森林（RF）算法和短板因子度量模型进行赋权,确定施工群的综合承载状况. 以兰新高铁的深路堑工程为例,构建考虑短板效应的木桶模型,并基于状态空间模型确定施工群的承载状态,结果显示：绿色施工效果与施工群承载状态的优劣成正相关;针对已有成果中雷达图的对比研究证实了所提出的模型与方法的可行性.     

RRR-RRP六杆机构的MATLAB运动学仿真

用复数推导了曲柄、RRR和 RRP 级杆组的位移、速度和加速度的复数表达式 ,并将其转化为适用于MATL AB仿真的矩阵数学模型 ,以该矩阵数学模型编制了相应的 M函数仿真模块 ,对给定的 RRR- RRP六杆 级机构为例说明如何使用这三个仿真模块建立 MATL AB仿真模型 ,并对其仿真结果的正确性加以分析。其主要思想是以组成机构的杆组为仿真模块 ,搭建各种机构 MATL AB仿真模型 ,可以对各种低副机构进行运动学仿真和分析     

精密微小型制造理论、技术及其应用

以中间尺度的微小型构件为目标,以传统制造技术为基础,提出精密微小型制造技术概念和主要内涵.提出并实现了高转速数控精密微小型车铣复合加工技术,研究在微小型车铣复合加工中心上进行微小型零件完整性加工的工艺技术及特性.针对超薄、异型微小型金属构件的制造,提出大功率高频群脉冲电化学微小型制造方法和工艺.提出并初步研究基于制造特征仿真的相关理论和建模方法,介绍应用实例.提出基于工艺匹配原则的计算机显微检测技术,介绍关键技术研究进展.     

褐煤与大豆荚共热解的产物特性分析

利用自制的低温热解装置研究褐煤与大豆荚共热解的产物特性,考察大豆荚掺混比和催化剂Fe₂O₃对热解产物特性的影响。通过FT-IR、GC-MS、SEM-EDX和UV-vis分析共热解产物的性质,并将半焦用于亚甲基蓝吸附实验。研究结果表明：掺混比30%时,共热解焦油的产率达到最大值11.98%,比煤焦油产率增加44.86%,与计算值的正偏差最大（0.8%）,同时,大豆荚的添加有促进焦油生成的协同作用。大豆荚的添加有利于共热解焦油中含氧杂环的断裂,使共热解焦油中直链烷烃增多,芳香族化合物减少,使重质组分转化为轻质组分,从而提高焦油品质;同时,大豆荚的添加使共热解半焦的含氧基团增加,微观形貌变粗糙。而Fe₂O₃的加入使共热解焦油中酚、醇类物质增加;加Fe₂O₃共热解半焦的褶皱更加明显。共热解半焦对亚甲基蓝的吸附率为33.62%,比煤半焦的吸附率提高8.84%,加Fe₂O₃共热解半焦的吸附率为55.57%,比共热解半焦提高65.29%。     

A novel organizing scheme of single topic user group based on trust chain model in social network

Social network sites (SNS) presently face the task of grouping users into small subsets within themselves. In this study, an organizing scheme for single‐topic user groups is proposed for facilitating user sharing and communicating under common interests. The main rationales of the proposed scheme are (1) only an influential single topic is selected through its impact evaluation to attract users; (2) only the users having high degree of interest, explicit or implicit, on the topic should be grouped; and (3) trustworthy relationships among users are taken into consideration to enlarge the scale of user group. The proposed organizing scheme comprises 3 features: topic impact evaluation, interest degree measurement, and trust chain‐based organizing. The main structure of our proposed scheme is (1) an overview of the proposed scheme and its formal related definitions; (2) a topic impact evaluation method, ie, an importance evaluation and a popularity calculation; (3) a user interest degree measurement method, ie, explicit and implicit interest evaluation with dynamic factors included; (4) a trust chain calculation method based on the topology features of the trust chain; (5) an organizing algorithm for single topic user group, and finally, some experimental results and discussions to illustrate the effectiveness and feasibility of our scheme.     

Compact microstrip low pass filter with flat group-delay using triangle-shaped resonators

In this paper, a compact microstrip lowpass filter (LPF) using triangle-shaped resonators is presented. The designed LPF includes three symmetric triangle-shaped resonators to provide a suitable passband and sharp response. A suppressing unit composed of several suppressing cells is designed to obtain a wide rejection band and low insertion loss in the passband. The fabricated LPF has been measured and indicts that it has −3 dB cut off frequency at 5.15 GHz. The rejection band has been expended from 5.51 GHz to 43.2 GHz with maximally flat return loss in this region nearby to 0 dB. Also, simulation and experimental results show that the proposed filter has a very flat group delay in the passband, which is the minimum value in comparison with the published works since 2017.     

Efficient communication protocol of group negotiation in VANET

An efficient communication protocol of group negotiation was proposed.The protocol adopted self-checking authentication in group to avoid the nodes sending certificates to the authentication center which improved the efficiency of identification.At the same time,the group establishment among nodes which through negotiation ensured the communication confidentiality and prevented the phenomenon of single-point failure.Besides,a group key transmission scheme was proposed to reduce the frequency of authentication for legal vehicles and improve the speed of joining in the group.At the end,theoretical analysis and simulation results demonstrate that the proposed protocol not only meets the security requirements of communication in VANET,but also shows much better performance than previous reported schemes on verification delay,transmission overhead and average delay.     

整形为平顶洛伦兹光束的非球面透镜组研究

高斯光束整形为均匀平顶光束在激光加工、激光驱动核聚变等方面有着重要应用。以平顶洛伦兹函数作为输出光束强度分布,采用非球面透镜组整形方案,通过分析平顶洛伦兹函数阶数和半高宽对整形效果的影响,使用最小二乘法拟合非球面面型,最后透镜组由ZEMAX软件进行光学仿真,结果表明,选用阶数为25,半高宽增大时,整形效果越好,在中心一定区域能达到理想的平顶光束输出。     

2D Group IVB Transition Metal Dichalcogenides

Semiconductor technology is currently impaired by the surface dangling bond of materials, which introduces scattering and interface traps. 2D materials, especially transition metal dichalcogenides (TMDs) with different main groups, have settled this issue by utilizing unique atomically smooth surfaces and van der Waals (vdW) structures. Over the past few decades, many processes for exploring new materials, manipulating physical properties, and synthesizing single crystals have been developed. Among these 2D materials, group IVB TMDs are distinguished for their splendid physical properties, including ultrahigh mobility, charge density wave, superconducting transitions, etc. Here, the recent advances in group IVB TMDs are reviewed, which offer easy access to next generation nano-, opto-, thermal-electronic, energy storage and conversion applications. Both the advantages and challenges of these studies are summarized to further clarify existing problems.     

CSCD系统的集成模型和实现方法

计算机支持协同设计(CSCD)是计算机支持协同工作(CSCW)的一个重要分支，CSCD系统(CSCDS)是CSCD的具体实现。在介绍CSCDS技术基础的基础上，提出了CSCDS的集成模型和实现方法。