共查询到20条相似文献，搜索用时 140 毫秒
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本文针对某型号摆线针轮减速机的故障原因，对摆线齿形进行了优化设计，改善了齿面受力情况，满足了实际生产应用。 相似文献
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以仙居县植绒针厂的植绒针生产工艺为研究对象，应用价值工程的原理从价值和功能等方面进行分析，然后在保证产品必要功能的前提下，对植绒针的生产工艺进行了改进，从而达到降低生产成本、提高经济效益的目的。 相似文献
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大针茅草原养育了各种野生动物和家畜 ,主要是马、牛、羊等 ,形成特殊的草原生态系统 ,对人类做出了重大的贡献。但针茅的颖果为针状并具带钩刺 ,易扎入羊皮内 ,尤其是细毛羊受到很大的危害 ;本文根据从 60年代以来所做的各方面努力 ,提出针对大面积针茅草原的放牧管理措施 ,为天然草场改良及草畜一体化实施专项针对性讨论提供参考 相似文献
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改变造林模式,营造针阔混交林势在必行,也符合科学发展观的要求,针对这一问题进行了论述。 相似文献
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针对客运专线隧道仰拱施工采用传统小块铜模不可克服的缺陷，开发了针梁式仰拱衬砌滑行模架，详细阐述了针粱式模架的结构组成、工作原理、施工工艺和与传统小块钢模施工的优势，并总结了仰拱混凝土施工质量控制措施。 相似文献
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目的:探讨密闭式安全静脉留置针联合采血针采血和常规采血对电解质测定结果的影响。方法:采用密闭式安全型静脉留置针联合采血针采血与同一时间自身的同侧肢体(非输液侧肢体)常规采血,做配对对照,检测干生化电解质K+Na+CL-Ca2+值有无差异。结果:两种方法各时间段检测患者的干生化电解质K+Na+CL-Ca2+值差异无统计学意义(P0.05)。结论:密闭式安全型静脉留置针联合采血针采血,减轻患者痛苦,减少感染,减少护士针刺伤,提高工作效率。 相似文献
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The super-high strength of single-layer graphene has attracted great interest. In practice, defects resulting from thermodynamics or introduced by fabrication, naturally or artificially, play a pivotal role in the mechanical behaviors of graphene. More importantly, high strength is just one aspect of the magnificent mechanical properties of graphene: its atomic-thin geometry not only leads to ultra-low bending rigidity, but also brings in many other unique properties of graphene in terms of mechanics in contrast to other carbon allotropes, including fullerenes and carbon nanotubes. The out-of-plane deformation is of a ‘soft’ nature, which gives rise to rich morphology and is crucial for morphology control. In this review article, we aim to summarize current theoretical advances in describing the mechanics of defects in graphene and the theory to capture the out-of-plane deformation. The structure–mechanical property relationship in graphene, in terms of its elasticity, strength, bending and wrinkling, with or without the influence of imperfections, is presented. 相似文献
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利用差示扫描量热仪及扫描电子显微镜,分别对结构可控聚丙烯-b-聚甲基丙烯酸甲酯共聚物和聚丙烯-b-聚苯乙烯共聚物用于聚烯烃共混体系的热性能及相容性进行了研究.实验结果表明,这些功能化的聚丙烯嵌段共聚物基本上保持了原有聚丙烯高熔点等优良特性,并对它们相应共混体系有明显的增容作用.另外,这些功能化的聚丙烯嵌段共聚物能提高它们相应共混体系的弯曲强度和弯曲模量等力学性能. 相似文献
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Wen Xing Peng Shi Ramesh K. Agarwal Yuxin Zhao 《Journal of The Franklin Institute》2019,356(6):3590-3611
In practice, it is almost impossible to directly add a controller on each node in a complex dynamical network due to the high control cost and the difficulty of practical implementation, especially for large-scale networks. In order to address this issue, a pinning control strategy is introduced as a feasible alternative. The objective of this paper is first to recall some recent advancements in global pinning synchronization of complex networks with general communication topologies. A systematic review is presented thoroughly from the following aspects, including modeling, network topologies, control methodologies, theoretical analysis methods, and pinned node selection and localization schemes (pinning strategies). Fully distributed adaptive laws are proposed subsequently for the coupling strength as well as pinning control gains, and sufficient conditions are obtained to synchronize and pin a general complex network to a preassigned trajectory. Moreover, some open problems and future works in the field are also discussed. 相似文献
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涂层混凝土在应力腐蚀条件下氯离子渗透性能的变化是一个新的课题。本文利用自行设计的加载设备对混凝土保护涂层及涂层涂刷次数等不同情况下的氯离子渗透性进行了研究。研究表明,保护涂层减小了混凝土在应力腐蚀环境作用下抗弯强度的损失。同时也提高了混凝土的抗氯离子渗透性,而且随着保护涂层刷涂次数的增加这种优越性越明显。 相似文献
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The analysis of circular concrete columns using unconfined concrete models is a well established practice. However, there is a necessity to develop realistic analysis and design tools that predict the extreme ultimate capacity of such columns since modern codes and standards like AASHTO LRFD are introducing extreme load events. The increase in strength and ductility due to full axial confinement is not applicable to pure bending and bending plus axial load simply because the area of effective confined concrete is reduced. The higher the eccentricity the smaller the compressed portion of the confined core. Accordingly, the ultimate confined strength is gradually reduced from the fully confined value fcc′ (at zero eccentricity) to the unconfined value fc′ (at infinite eccentricity) as a function of eccentricity to diameter ratio. A numerical analysis algorithm is developed using the finite layer procedure and the secant stiffness approach within a framework of incremental-iterative moment of area computations. The resulting nonlinear section analysis requires radial loading in which the eccentricity is kept constant or the axial load is proportional to the applied moment. The results are compared with existing experimental data and the widely used Mander model to benchmark the present predictions. 相似文献
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The seamless integration of reagents into microfluidic devices can serve to significantly reduce assay complexity and cost for disposable diagnostics. In this work, the integration of multiplexed reagents into thermoplastic 2D microwell arrays is demonstrated using a scalable pin spotting technique. Using a simple and low-cost narrow-bore capillary spotting pin, high resolution deposition of concentrated reagents within the arrays of enclosed nanoliter-scale wells is achieved. The pin spotting method is further employed to encapsulate the deposited reagents with a chemically modified wax layer that serves to prevent disruption of the dried assay components during sample introduction through a shared microchannel, while also enabling temperature-controlled release after sample filling is complete. This approach supports the arbitrary patterning and release of different reagents within individual wells without crosstalk for multiplexed analyses. The performance of the in-well spotting technique is characterized using on-chip rolling circle amplification to evaluate its potential for nucleic acid-based diagnostics. 相似文献
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C25-8.83/0.981是一台抽汽供热式汽轮发电机组.该机组在启动调试过程中,发现其存在四号轴承轴向振动超标故障、发电机转子热不平衡故障和汽轮机动静碰磨故障等问题.本文通过启动运行过程中对机组参数监控及轴系振动的监测,经过对现象及相关数据的分析,并在停机过程中多次进行调整.最终确定四号轴承轴向振动超标的主要原因是由于该轴承球面与球面座定位销错位,引起定位销卡涩,从而使激振力投影点与轴承几何中心不重合,致使四号轴承轴向振动过大.而发电机转子热不平衡和汽轮机动静碰磨的故障现象是在机组并网带负荷运行过程中四号轴承和二号轴承相继振动过大.经分析判断,主要是由于发电机转子在运行过程中发生了热弯曲,从而造成发电子转子热不平衡,产生较大的轴向振动,进而影响到汽轮机转子并致使动静碰磨造成二号轴承振动过大.最终通过现场动平衡,加配重,才使这一问题得到较好的解决. 相似文献
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先张法预应力混凝土管桩,尤其是薄壁管桩抗弯能力不足,往往由于施工过程土侧压力或位移造成管桩出现裂缝或其他工程问题。因此,提高管桩抗弯能力对避免或减少管桩工程质量事故有一定的作用。管桩是一空心细长预应力混凝土预制构件,在沉桩过程当中除受到竖向压力(或打击力)外,由于相邻桩沉桩过程土体的侧移挤压作用,使得已沉管桩还受到水平推力的作用。所以管桩可以视为一受弯或压弯构件来建立受力模型。因此,提高管桩抗弯能力也就是要提高管桩抗侧变形能力。本文通过实验和数值分析表明在预应力混凝土管桩中添加钢筋混凝土横隔,能提高管桩的抗弯和变形能力。 相似文献