Strengthening of Preloaded RC Beams Using Hybrid Carbon Sheets

Reinforced concrete (RC) beams subject to service loads of 40 or 60% of steel yielding were strengthened using hybrid continuous carbon fiber sheets. The hybrid systems were made of high-strength and high-modulus carbon sheets, and compared with systems using only high-strength carbon. It was found that the use of high-modulus carbon sheets in hybrid systems could increase the yielding load, the flexural stiffness, the postyielding ductility, and reduce the crack opening in concrete. The slope changes on load-deflection curves at steel yielding are not noticeable in hybrid systems. The tensile strains developed in hybrid sheets after the fracture of high-modulus carbon are higher in magnitude and distributed in a larger area, leading to an ultimate carbon fracture with concrete crushing. These unique features are attributed to the high stiffness and low ultimate tensile strain of the high-modulus carbon fibers which stiffen the structures, avoid or delay the fiber-reinforced polymer debonding, and facilitate the deformability during their subsequent breakdown.     

多功能滚齿机的数字控制系统

本文叙述了以ＳＴＤＰＣ／ＸＴ（或ＰＣ／ＡＴ）机为主要核心构成的滚齿机数字控制系统的结构，软件设计和特点，系统采用混合语言编程，极大地提高了软件设计的灵活性与快速性，也分析了ＣＮＣ系统的加工过程，提出了加工中的软件预处理控制方法，并给出了轴伺服控制的并行算法分析与实现。     

等离子体聚合有机膜的离子注入改性

以苯胺为单体在等离子体条件下进行聚合，测量所合成的有机膜经１００ｋｅＶ、５×１０１５ｃｍ￣（－２）Ａｒ￣＋注入后电阻率的变化，并用ＦＴＩＲ、ＸＰＳ和核分析方法对离子注入引起的结构和成分改变进行了探讨。结果表明，在等离子体环境下，聚合膜内仍含有大量环结构。由于Ａｒ￣＋的注入，聚合膜表面损伤而碳化，使注入层内的体电阻率降低１１个数量级。     

用正电子湮没寿命技术研究塑性变形纯Ni的回复过程

本文用正电子湮没寿命方法研究了塑性变形镍(含0.01％杂质)的回复过程的特点及杂质在缺陷回复过程的作用和影响,计算了形变为10％的试样中的位错密度及形成空位团的有效空位浓度。     

粉煤灰填充PVC树脂的研究

采用ＷＡＸＤ、ＳＥＭ和力学测试等方法对不同粒度和不同含量的粉煤灰（ＰＦＡ）与聚氯乙烯（ＰＶＣ）共混物的结构形态、力学性能进行了测定。结果表明，ＰＦＡ粒度对ＰＶＣ／ＰＦＡ共混物的性能具有明显影响，当ＰＦＡ粒度尺寸达到一定程度时，再降低ＰＦＡ粒度尺寸对共混物的性能影响不大。随着ＰＶＣ／ＰＦＡ共混物中ＰＦＡ含量的增加，拉伸强度和拉伸模量增大，但伸长率降低。     

Melting behaviors, isothermal and non-isothermal crystallization kinetics of nylon 1212

Isothermal crystallization, subsequent melting behavior and non-isothermal crystallization of nylon 1212 samples have been investigated in the temperature range of 160-171 °C using a differential scanning calorimeter (DSC). Subsequent DSC scans of isothermally crystallized samples exhibited three melting endotherms. The commonly used Avrami equation and that modified by Jeziorny were used, respectively, to fit the primary stage of isothermal and non-isothermal crystallizations of nylon 1212. The Avrami exponent n was evaluated, and was found to be in the range of 1.56-2.03 for isothermal crystallization, and of 2.38-3.05 for non-isothermal crystallization. The activation energies (ΔE) were determined to be 284.5 KJ/mol and 102.63 KJ/mol, respectively, for the isothermal and non-isothermal crystallization processes by the Arrhenius' and the Kissinger's methods.     

关于建立健全交通基础设施长寿命安全保障体系的战略思考

本文主要针对我国交通基础设施存在的结构病害严重、"短寿命"突出、"老龄化"日益凸显、长寿命安全服役面临严峻挑战等问题,借鉴发达国家的先进经验,提出了我国交通基础设施长寿命安全保障体系建设的总体目标、战略任务及相关建议,并开展了交通基础设施长寿命安全保障体系的系统研究和建设工作,对确保其长寿命安全服役和交通大动脉的安全畅通、支撑国民经济可持续发展、保障人民生活安稳有序、助力国家安全和社会稳定具有十分重要的战略意义。     

火焰喷涂聚酰胺12/n-SiO2复合涂层工艺及性能

采用火焰喷涂法制备了聚酰胺12(PA12)及聚酰胺12/纳米SiO2(n-SiO2)复合涂层,并利用电子拉力机、摩擦磨损试验机、红外光谱仪(FTIR)和示差扫描量热仪(DSC)等对涂层的结构与性能进行了研究.红外光谱分析表明PA12及PA12/n-SiO2粉末在火焰喷涂过程中没有发生氧化或降解反应,表明火焰喷涂法适宜制备PA12及PA12/n-SiO2复合涂层;DSC分析结果表明n-SiO2具有成核剂作用,能提高PA12大分子的结晶速度及结晶度;涂层力学性能及摩擦磨损性能分析表明n-SiO2能提高涂层的力学性能,改善涂层的耐老化性能和摩擦磨损性能.当n-SiO2添加量为1.5%(质量)时,涂层综合性能最佳.     

基于VMD的故障特征信号提取方法

变模式分解(variational mode decomposition,简称VMD)能够将多分量信号一次性分解成多个单分量调幅调频信号(variational intrinsic mode function,简称VIMF),但对噪声比较敏感。利用VMD对噪声的敏感特性,提出了一种基于VMD的降噪方法。利用排列熵定量确定VMD分解后各分量的含噪程度,对高噪分量直接剔除,对低噪分量进行Savitzky-Golay平滑处理,然后重构信号。运用该方法降噪后,对重构信号进行变模式分解,能够有效提取故障特征信号。仿真和实例分析表明,基于VMD的降噪方法的降噪效果优于小波变换降噪方法,VMD能有效提取故障特征信号。