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1.
节点连接的破坏和失效显著影响装配整体式混凝土框架结构在连续倒塌大变形下的抗力机理、破坏模式和变形能力。为研究装配整体式混凝土框架结构的抗连续倒塌性能,设计了3个1/3缩尺的两跨梁柱子结构试件,开展了拟均布加载下的静力连续倒塌试验和理论计算分析。包含1个现浇对比试件RC和2个采用不同梁柱纵筋连接方式的装配整体式试件PC,即梁钢筋通过机械套筒连接和锚固板锚固、柱钢筋通过半灌浆套筒连接的试件,梁钢筋通过90°弯折锚固、柱钢筋通过约束浆锚连接的试件。试验发现:由于后浇区混凝土强度的提高,装配整体式试件的压拱机制峰值荷载较现浇对比试件分别提高22.9%和20.2%;拟均布加载下,梁最终变形呈曲线,该变形模式下节点需要提供更高的转动能力才能保证梁整体变形满足T/CECS 392—2021《建筑结构抗倒塌设计标准》的挠度要求;在悬链线峰值荷载时相邻跨梁提供的水平约束能有效限制边柱的水平变形和装配式试件的坐浆层滑移。理论计算表明,装配整体式试件的压拱作用的倒塌抗力贡献率低于现浇对比试件,其原因是边柱坐浆层滑移削弱了梁端约束,进而降低了压拱机制承载力。采用能量原理评估了试件的动力倒塌抗力,由于压拱机制下的累积耗能能力较高,装配整体式试件的动力倒塌抗力分别比现浇试件提高了16.8%和18.8%。  相似文献   
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In this article, energy efficient ensemble clustering method (EECM) with black widow optimization (EECM-BWO) algorithm is proposed for effective data transmission with the help of real time flood disaster monitoring wireless sensor network (WSN). Initially, unified scalable ensemble clustering algorithm based on ensemble generation and consensus function is proposed for selecting the optimal routing path among the node using BWO algorithm. Then, biologically inspired routing black widow spiders optimization algorithm is proposed to trade off the nodes energy level, self-organization, and self-configuration in the WSN. The simulation is performed using NS2 simulator for validating the performance of the proposed EECM-BWO method. Here, in node, low delay achieves 24.07%, 72.58%, 51.36%, 81.75%, 77.74%, high packet delivery ratio achieves 70.83%, 53.93%, 90.23%, 43.58%, 24.58%, low packet drop attains 77.93%, 72.76%, 61.56%, 51.87%, 34.35%, low energy consumption attains 75.9%, 52.94%, 65.81%, 58%, 41.2% compared with existing energy-efficient clustering approach consolidated game theory as well as dual-cluster-head mode for WSNs energy-aware clustering by cuckoo optimization approach (EECM-COA), energy-aware clustering-based routing using multi-path reliable transmission with routing and control board (EECM-RCB-MRT), adaptive repair algorithm with temporally ordered routing algorithms for flood control strategy (EECM-AR-TORA-FCS), passive multi-hop clustering algorithm (EECM-PMC), dynamic source routing protocol based on genetic algorithm-bacterial foraging optimization (DSR-GA-BFO).  相似文献   
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Most of the internet users connect through wireless networks. Major part of internet traffic is carried by Transmission Control Protocol (TCP). It has some design constraints while operated across wireless networks. TCP is the traditional predominant protocol designed for wired networks. To control congestion in the network, TCP used acknowledgment to delivery of packets by the end host. In wired network, packet loss signals congestion in the network. But rather in wireless networks, loss is mainly because of the wireless characteristics such as fading, signal strength etc. When a packet travels across wired and wireless networks, TCP congestion control theory faces problem during handshake between them. This paper focuses on finding this misinterpretation of the losses using cross layer approach. This paper focuses on increasing bandwidth usage by improving TCP throughput in wireless environments using cross layer approach and hence named the proposed system as CRLTCP. TCP misinterprets wireless loss as congestion loss and unnecessarily reduces congestion window size. Using the signal strength and frame error rate, the type of loss is identified and accordingly the response of TCP is modified. The results show that there is a significant improvement in the throughput of proposed TCP upon which bandwidth usage is increased.  相似文献   
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In recent years, Software Defined Networking (SDN) has become an important candidate for communication infrastructure in smart cities. It produces a drastic increase in the need for delivery of video services that are of high resolution, multiview, and large-scale in nature. However, this entity gets easily influenced by heterogeneous behaviour of the user's wireless link features that might reduce the quality of video stream for few or all clients. The development of SDN allows the emergence of new possibilities for complicated controlling of video conferences. Besides, multicast routing protocol with multiple constraints in terms of Quality of Service (QoS) is a Nondeterministic Polynomial time (NP) hard problem which can be solved only with the help of metaheuristic optimization algorithms. With this motivation, the current research paper presents a new Improved Black Widow Optimization with Levy Distribution model (IBWO-LD)-based multicast routing protocol for smart cities. The presented IBWO-LD model aims at minimizing the energy consumption and bandwidth utilization while at the same time accomplish improved quality of video streams that the clients receive. Besides, a priority-based scheduling and classifier model is designed to allocate multicast request based on the type of applications and deadline constraints. A detailed experimental analysis was carried out to ensure the outcomes improved under different aspects. The results from comprehensive comparative analysis highlighted the superiority of the proposed IBWO-LD model over other compared methods.  相似文献   
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Annihilation of vacancy clusters in monolayer molybdenum diselenide (MoSe2) under electron beam irradiation is reported. In situ high-resolution transmission electron microscopy observation reveals that the annihilation is achieved by diffusion of vacancies to the free edge near the vacancy clusters. Monte Carlo simulations confirm that it is energetically favorable for the vacancies to locate at the free edge. By computing the minimum energy path for the annihilation of one vacancy cluster as a case study, it is further shown that electron beam irradiation and pre-stress in the suspended MoSe2 monolayer are necessary for the vacancies to overcome the energy barriers for diffusion. The findings suggest a new mechanism of vacancy healing in 2D materials and broaden the capability of electron beam for defect engineering of 2D materials, a promising way of tuning their properties for engineering applications.  相似文献   
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机车运行的过程中齿轮箱传动系统不仅受到传递载荷、轮轨冲击载荷的联合影响,而且还要适应轮对、构架之间复杂的相对运动,导致齿轮传动系统出现故障的情况下采集到的信号成分复杂并且具有明显调制现象。该文针对齿轮系统含有齿根裂纹故障情况下采集到的信号调制现象进行解调方法研究。首先,通过数值仿真方法得到轮对、电机、构架以及车体等机车部件在齿轮箱齿轮含有齿根裂纹故障情况下的振动信号;然后,运用仿真得到的电机振动信号对多种解调方法进行对比分析,通过数据分析得到一种适合机车齿轮箱齿根裂纹故障的解调方法。结果表明基于复Morlet小波簇的梳状滤波器的解调方法可以对机车振动信号进行有效的解调。  相似文献   
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叙述了车用连接导通制件中成对铜片的冲裁弯曲成形工艺,介绍了制件的排样及模具结构设计特点,并对模具主要工作零件进行设计,阐述了切断活动凹模镶件的设计。模具经生产实践证明:模具结构紧凑合理,成形的制件形状和尺寸达到图纸技术要求,可为同类制件的模具设计提供参考。  相似文献   
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通过对螺母板的工艺分析与计算,提出采用落料、拉深、镦挤、翻边及弯曲的多工位级进模冲压来实现该制件自动化生产。介绍了该制件的排样方案及模具总体结构设计,说明了结构设计的特点。为使厚料拉深的毛坯能顺利地流入到拉深凹模内(有利于材料塑性变形),该模具采用工艺伸缩带来连接制件与载体。经多年来的生产验证,该模具结构新颖、合理、可靠,冲压出的制件质量稳定、生产效率高,可为类似制件的模具设计提供相关参考。  相似文献   
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