关键词： Polymer composite   Mechanical properties   Interface   Molecular dynamics  

摘要： We investigate the mechanical behavior of polypropylene/silica composites under mode I and II loading by using molecular dynamics simulations, focusing on the effects of two typical surface coupling agents of HMDZ and APTES on the interface deformation and failure. It is found that under mode I loading, the silica surface functionalized with APTES can enhance the tensile strength of polypropylene/silica composites effectively. In contrast, the silica surface functionalized with HMDZ has little effect on the tensile strength. The simulation results are supported by experiments. Under mode II loading, it is found that both HMDZ and APTES can enhance the shear strength of polypropylene/silica composites with APTES being more effective. The underlying mechanisms for the enhancement of interface strength are analyzed. Our work provides a deep understanding of the interface structure, deformation and failure and will be useful for selecting suitable surface coupling agents in enhancing the interface strength of polymer composites.

关键词： Nickel doping   Adsorption regeneration   In situ decontamination   Cationic and anionic dyes   Synergistic effect  

摘要： Iron-nickel bimetallic organic frameworks (FeNix-BDC, H2BDC: terephthalic acid) were developed as bifunctional materials for adsorption and photo-Fenton degradation of organic dyes with different charge properties. Significantly enhanced adsorption capacity of FeNi1/15-BDC towards methylene blue (MB) and methyl orange (MO) was achieved, 5.3 and 2.6 times higher than that of pristine Fe-BDC, which was attributed to enlarged specific surface area and pore volume and the decreased surface charges induced by Ni doping. The adsorption kinetics demonstrated that chemisorption was dominant and intra-particle diffusion was the rate-controlling step. Two-stage degradation including slow induction stage and rapid oxidation stage fitted with pseudo-zeroorder kinetics well. The increased rate constants (2.472 vs. 1.188 min(-1) for MB;0.616 vs. 0.421 min(-1) for MO) in the induction stage as well as the superior removal capability by asynchronism relative to synchronism jointly corroborating the improved adsorption performance was favor for subsequent degradation. Notably, this heterogeneous system not only exhibited obvious advantages like wider pH working range (3-9), better stability and reusability of catalysts, but also achieved the dual objectives of in-situ decontamination and adsorbent regeneration. The coupling of adsorption and degradation along with synergism between photocatalysis and Fenton-like process are responsible for the reinforced removal of organic contaminants.

关键词： 2-Amino-3-cyanopyridine   Aldehyde   Amines   Chemically-Controlled   Cyclohexanone   Fructose   Kinetics   Malononitrile  

摘要： 2-Amino-3-cyanopyridine derivatives have been synthesized via a four-component reaction of malononitrile (1), aromatic aldehyde (2), cyclohexanone (3), and amines (4) in the presence of fructose and maltose catalysts with good to excellent yields. In addition, for the first time we describe the experimental kinetics study and a full mechanistic investigation of title reaction. To determine the right position of each component in the reaction path, kinetic study of the reaction was carried out using UV-vis spectrophotometry technique. Based on temperature effects on the reaction rate, activation energy (E-a= 28.97 +/- 0.21 kJ mol(-1)) and its parameters (Delta H-double dagger = 26.49 +/- 0.23 kJ mol(-1), Delta S-double dagger = -122.88 +/- 0.67 J mol(-1 )K(-1) and Delta G(double dagger) = 63.12 +/- 0.46 kJ mol(-1)) were determined, so the reaction was enthalpy and chemically controlled and also its mechanism was associative. By the change in the solvent polarity, it was found that polar solvents increase the reaction rate and the mixture of water/ethanol (50/50) was the best choice. Changing the structure of aniline (4) and benzaldehyde (2) by the substituent groups exhibited that the reaction proceeds faster in a poor electronic ring, regarding benzaldehyde (2), which is the result of the electron-withdrawing groups and a rich electronic ring for aniline, which is because of the electron donating groups. Further investigations on the partial orders of reactants approved the independency of the rate law to the concentrations of components (3) and (4), so the reaction was second-order kinetics corresponding to compounds (1) and (2) with the right rate law = k7k2k112Catk-6. Step(7) was recognized as the RDS.

关键词： 产业化应用   商用车   混合动力系统   城际交通   复合驱动   能量回馈   节能减排   尾气排放  

摘要： 商用车是我国城市、城乡、城际交通与运输的重要运载工具。2017年全国商用车保有量达2800万辆,产销量420万辆(占全球20%)。据统计,我国商用车燃油消耗达1.22亿吨/年(占石油总消耗21.9%),北京等城市的大气颗粒物中,商用车尾气排放占40%以上。因此,商用车节能减排需求迫切。混合动力(简称"混动")系统利用发动机与电机复合驱动,以及能量回馈复合制动等新技术,可显著降低内燃动力车辆能耗和排放,是解决该问题最重要的途径之一。然而,我国混合动力技术严重缺失,商用车并联混动市场被美国伊顿公司垄断。

关键词： 动力设备   机械振动控制   位移量   振动信号  

摘要： 为增强船舶动力设备机械振动控制效果,设计一个船舶动力设备机械振动控制模型。设定船舶动力设备机械振动控制模型,依据采集的振动信号模型得到机械振动位移量,同时依据位移量提出控制计算方法,以此完成船舶动力设备机械振动控制。实验结果表明,所设计的船舶动力设备机械振动控制模型加强了船舶在低频激励下的效果,并降低了机械振动控制的控制误差,具备实际应用的意义。

关键词： 湿喷台车机械臂   三维模型   运动学   动力学  

摘要： 针对混凝土湿喷台车机械臂的结构特点,采用D-H法建立连杆坐标系,推导出运动学和动力学方程。在此基础上,基于MATLAB Robotic Toolbox对混凝土湿喷台车机械臂进行运动学仿真分析,建立仿真模型并求解工作空间,验证所建运动学模型的正确性。采用ADAMS建立湿喷台车机械臂动力学模型,对两种最危险工况分别进行研究,计算动作油缸的最大载荷,并探究其随油缸位移的变化情况,仿真结果为机械臂与油缸的设计提供了一定的参考依据。

关键词： 多体动力学   机械工程   工程应用  

摘要： 多体动力学在现阶段一般是指多体的系统动力学,是一门较为复杂和综合性相对较强的力学学科,在机械工程领域中占据重要地位。结合多体动力学相关概念,介绍多体动力学在机械工程中的应用,为相关工程的应用提供一定的参考。

关键词： 机械通气   急性呼吸窘迫综合征   右心室收缩压   血压   血流动力学  

摘要： 目的探讨不同潮气量(VT)机械通气对油酸(OA)诱导急性呼吸窘迫综合征(ARDS)大鼠右心血流动力学的影响。方法将60只雄性SD大鼠按随机数字表法分为对照组(n=20)、ARDS模型组(n=20)、小VT组(n=10)和大VT组(n=10)。经大鼠颈总静脉注入OA 0.15 mL/kg制备ARDS模型;对照组给予等量生理盐水。ARDS模型组制模后2 h取10只大鼠测定氧合指数(PaO_(2)/FiO_(2));取肺组织测定湿/干重比值(W/D),光镜下观察肺组织病理学改变并进行肺损伤评分,以确定模型制备是否成功。小VT组和大VT组于制模后2 h分别给予大鼠VT为6 mL/kg或20 mL/kg的机械通气4 h;对照组和ARDS模型组保持自主呼吸。机械通气4 h后,测定大鼠心率(HR)、右心室收缩压(RVSP)、右室内压上升最大速率(dp/dt max)和血压(BP),同时取动脉血进行血气分析〔pH值、动脉血氧分压(PaO_(2))、动脉血二氧化碳分压(PaCO_(2))、PaO_(2)/FiO_(2)〕。结果制模后1 h,ARDS模型组大鼠即出现呼吸窘迫症状。制模后2 h,大体观察可见肺脏外观有明显点片状出血;对照组无上述改变。ARDS模型组大鼠PaO_(2)/FiO_(2)较对照组显著降低〔mmHg(1 mmHg=0.133 kPa):294.3±5.9比459.0±4.4,P<0.01〕,肺W/D比值和肺损伤评分均较对照组明显升高〔肺W/D比值:8.24±0.25比4.48±0.13,肺损伤评分(分):0.60±0.03比0.12±0.02,均P<0.01〕,提示ARDS模型制备成功。ARDS模型组大鼠动脉血气分析及血流动力学指标均较对照组明显恶化。机械通气4 h后,小VT组动脉血气分析指标均明显优于ARDS模型组和大VT组〔pH值:7.36±0.02比7.24±0.02、7.13±0.01,PaO_(2)(mmHg):92.4±2.1比61.8±2.3、76.6±2.2,PaCO_(2)(mmHg):49.6±1.7比61.8±1.8、33.6±1.3,PaO_(2)/FiO_(2)(mmHg):440.0±10.2比274.3±21.4、364.7±10.5,均P<0.05〕;小VT组HR、BP和dp/dt max明显高于ARDS模型组和大VT组〔HR(次/min):346.9±5.4比302.3±10.1、265.5±12.2,BP(mmHg):125.4±2.2比110.0±2.5、89.2±2.8,dp/dt max(mmHg/s):1393.3±30.3比1236.4±20.5、896.1±19.5,均P<0.05〕,而RVSP则明显低于ARDS模型组和大VT组(mmHg:31.3±0.4比34.0±1.0、38.8±0.9,P<0.05)。结论小VT机械通气可改善ARDS大鼠右心室的血流动力学参数,保护右心功能。

关键词： Graphene oxide   Nanocomposites   Molecular dynamics simulation   Surface roughness  

摘要： Based on the results of molecular dynamics (MD) simulations and a mean-field micromechanics model, we report on some positive contributions of the oxygen functional groups in single-layer graphene oxide (GO) to the mechanical and interfacial properties of polyethylene (PE)/graphene nanocomposites. As the epoxide and hydroxyl group degrade the mechanical properties of single-layer graphene, clear degradations in the longitudinal Young's and in-plane shear moduli are observed when the deformation of graphene is involved in the loading of the nanocomposite unit cells. However, a significant improvement in the longitudinal shear modulus of nanocomposites is predicted. By comparing the MD simulation results with double-inclusion (D-I) model predictions, contributions of the interphase zone and the interfacial stiffening effect to the elasticity of nanocomposites are again confirmed. Finally, we demonstrate a novel evolution of the out-of-plane normal stress and longitudinal shear stress in single-layer GO arising from its interaction with the surrounding PE matrix via atomic virial stress.