密集弹片群对钢筋混凝土墙体的整体破坏效应分析

常规弹头爆炸后,不仅产生空气冲击波,同时也产生大量高速弹片,形成弹片群,和空气冲击波一样,弹片群也具有极大的破坏杀伤能力。对于建筑结构而言,密集弹片群不仅产生聚集局部破坏效应,还会将能量传递到结构,使之产生整体破坏效应,这是单个弹片与密集弹片群破坏效应的主要区别之一。采用数值模拟的方法对弹片群的整体破坏效应进行了初步研究,描绘钢筋混凝土墙体在弹片群冲击作用下的动态响应过程,揭示弹片群的整体破坏效应,与冲击波在同一量级,在结构设计中不可忽视。     

廊空间在建筑外部空间设计应用初探

本文试从建筑外部空间的角度分析建筑廊空间的产生,并结合实例深入分析了廊空间在外部空间设计应用中的三种基本类型以及所产生的影响.     

Rewritable Optical Memory Through High‐Registry Orthogonal Upconversion

An experimental design, based on a combination of core–shell‐structured upconversion nanoparticles and diarylethene photochromic molecules, for achieving rewritable optical memory is reported. This core–shell design enables the nanoparticles to emit two sets of distinct emission bands with ultrahigh spectral purity through laser excitation at 980 and 1532 nm. Importantly, the ultraviolet emission of the nanoparticles under 980 nm irradiation is used to activate the cyclization reaction of diarylethene through C? C bond formation, while the green emission from the nanoparticles upon 1532 nm excitation leads to the cleavage of the newly formed C? C bond. This pathway offers a convenient and versatile optical method for controlling the process of data writing and erasing with high spatiotemporal resolution.     

水轮机微机调速器PID参数的智能化设置

当前,大型机组调速器的国产化条件日渐成熟.相对于进口设备,中国的硬件水平还有一定的差距,但在软件方面,设计理念已处于国际先进水平.在机组空载工况下如何整定PID参数及防止参数间配合不合理,是水轮机调节关心的问题.文中提出一种调速器PID参数合理搭配的判断和提示方法,该智能化设置使得调速器能够稳定工作,避免因参数不合理而导致非正常停运.     

A Si–SiC Oxidation‐resistant Coating for Carbon/Carbon Composites by Hot‐pressing Reaction Technique

A Si–SiC coating was prepared by hot‐pressing reactive sintering (HPRS) technique for protecting carbon/carbon (C/C) composites against oxidation. The Si–SiC coating has a dense and crack‐free structure with a thickness of 70–90 μm. The Si–SiC coating by HPRS has a higher SiC content and lower Si content than the coating by pressure‐less reactive sintering (PRS). It also exhibits better oxidation‐protective ability than that prepared by PRS. With hot‐pressing, the flexural strength of the Si–SiC coated C/C composites decreases from 121 MPa to 99 MPa, and the interface bonding strength increases from 6 MPa to 10 MPa.     

回收尼龙的扩链改性研究

研究了回收尼龙扩链改性中扩链剂KL-E4370用量、吸酸剂的品种、共混条件对扩链效果的影响。结果显示,扩链剂KL-E4370用量为2%,吸酸剂氧化镁用量为2%,加工温度230℃,主机频率为8Hz下改性效果最好。     

碳纤维增强碳复合材料高温抗氧化硅基陶瓷涂层的研究进展(英文)

碳纤维增强碳(carbon fiber reinforced carbon,C/C)复合材料抗氧化问题一直是国际材料界研究的热点。硅基陶瓷作为C/C复合材料抗氧化涂层,是目前研究最深入的涂层体系。综述了国内外近几年C/C复合材料高温抗氧化硅基陶瓷涂层的研究进展,总结了C/C复合材料高温抗氧化硅基陶瓷涂层的制备工艺和对已有工艺的改进方法,分析了硅基陶瓷涂层在高温空气中、燃烧环境中的氧化失效机理。结合硅基非氧化物陶瓷(SiC,Si3N4等)环境障碍涂层的发展,展望了C/C复合材料在复杂环境中抗氧化涂层的研究方向。     

基于盾构掘进参数分析的隧道围岩模糊判别

以重庆主城越江排水隧道工程的地层条件为背景,基于施工现场盾构掘进试验,运用模糊数学方法,对盾构掘进过程中隧道围岩状况判别的理论和方法进行了研究。结合盾构掘进的特点和刀盘切割岩石的基本原理,提出了比推力和比扭矩的概念,建立了不同围岩条件下的比推力(SF)和比扭矩(ST)模糊集合,探讨和揭示了刀盘比推力和比扭矩的关系,刀盘推力、扭矩及切深与地质条件的相关性及与不同围岩状况、盾构掘进状态的对应关系。研究表明,若比推力与比扭矩以较高的水平同步、均匀变化,说明盾构在较硬的均匀地层中掘进;若比推力与比扭矩均较小且同步、均匀变化,说明盾构在较软的均匀地层中掘进;若比推力与比扭矩的变化出现比例异常,则暗示盾构正在穿越断层破碎地段或遇到障碍物或盾构姿态不良等。该方法减少了盾构在此类地层下掘进的盲目性和停机次数,提高了掘进效率和施工安全度,可用于盾构隧道施工围岩状况的适时、定性判别。     

γ－HPTES偶联剂的合成及其在砼中的应用

合成了新型长链硅烷──γ－己二胺基丙基三乙氧基硅烷（γ－ＨＰＴＥＳ）偶联剂，确定了合成反应的条件，用红外光谱验证了其结构。研究了γ－ＨＰＴＥＳ作为砼减水剂的功能，表明其用量在０．８％～１．０％时具有显著的减水增强作用，减水率达３２．８％，二个月抗压强度提高２１％。     

Micro-pleating in carbon-carbon composites under a cyclic load

As preferred high-temperature structural materials, the potential applications for C/C composites are bound to involve cyclic loads. Therefore a clear understanding of the behavior of these composites under cyclic loads and a proper evaluation of their fatigue life are necessary if they are to be used in applications subjected to fluctuating stresses. The cyclic fatigue behavior of C/C composites, however, has been overlooked until recently[1,2]. So far, except for few investigations on the …