关键词： 弹性流体动力润滑   齿轮   凸轮   轴承  

摘要： 弹性流体动力润滑是润滑理论的一个重要分支,也是关系到高副接触机械零件使用耐久性和可靠性的关键技术问题。计算机模拟仿真技术、数值计算方法和弹流测试技术的发展,推动了弹流润滑理论的发展和该理论在高副零件摩擦副设计中的广泛应用。综述齿轮、凸轮、轴承3种高副接触零件基于表面粗糙纹理、轮齿修形、有限长接触、热效应、镀层等因素的弹流润滑研究发展概况。指出现代弹流润滑理论虽然在高副接触零件中的应用已逐渐接近工程实际要求,能够较可靠地解决实际工况下的润滑难题,但在非稳态效应和真实粗糙表面对高副零件弹流润滑的影响方面,高副零件弹流润滑的多重参数耦合、计算机仿真及相关实验验证方面,还须进一步深入研究。

关键词： 浅镇静   ICU   机械通气   呼吸动力学  

摘要： 目的探讨持续性浅镇静目标导向调控策略与常规镇静策略对ICU机械通气患者呼吸动力学的影响。方法选取2017年5月—2018年9月在哈尔滨市第四医院ICU病房中收治的机械通气患者90例,研究对象按照抛硬币的方法入组,对照组50例,试验组40例。实验组采用持续浅镇静目标导向调控方案进行持续浅镇静,对照组应用常规镇静方案,记录并比较两组干预实施前、实施后48h记录所有患者呼吸动力学指标:Cdny、Pplat、Ppeak和VT。结果实施干预前,两组机械通气患者呼吸力学指标比较差异无统计学意义(P>0.05);两种策略实施后48h,实验组Pplat、Ppeak明显降低,而Cd、VT显著升高,差异有统计学意义(P<0.05)。结论持续性浅镇静目标导向调控方案较常规镇痛镇静策略能够更快降低ICU病房中行机械通气患者的气道峰压、平台压,更大程度上增加患者的肺动态顺应性和潮气量,能够更有效的提高ICU机械通气患者镇静镇痛管理效率。

关键词： 机械制造   基础课程   教学策略  

摘要： 随着国民经济发展水平的不断提高,各个行业发展迅速,尤其是机械制造业的发展水平显著提高,但是在实际发展中仍旧面临着一些问题,其中最为明显的就是人才培养问题。通过设计课程教学的基本思路、鼓励开放式和互动式学习、多学科融合教学等措施能够有效提升高校人才培养质量,为机械行业输送优秀人才。

关键词： 动力机械强度与振动   课程改革   专题教学   产学研合作平台  

摘要： 动力机械及工程作为培养学术型机械人才的主要专业之一,为适应社会发展和国家政策的要求,需要各高校加强对该专业课程的教学改革。文章结合上海电力学院自身的电力特色,基于动力机械及工程专业,对"动力机械强度与振动"课程进行教学内容与教学模式方面的改革,同时优化课程考核标准,使得课程更具有针对性与专业性,为高校动力机械及工程专业课程教学质量的提升提供思路和参考。

关键词： Tensile strength  

摘要： Unveiling the fundamental thermal-oxidative aging mechanism and thermal degradation kinetics of the poly(decamethyleneterephthalamide) (PA10T)/ glass fiber (GF) composites under different aging temperatures (160 degrees C, 200 degrees C, and 240 degrees C) for 0-50 days will facilitate the understanding of the interaction between matrix PA10T and GF. The results revealed that the decrease of mechanical properties referring to tensile strength, flexural strength and notched impact strength, and the occurrence of debonding phenomenon between PA10T matrix and GF were increasingly obvious after longer aging time at higher aging temperature. At the same time, the decline of crystalline was mainly ascribed to the thermal-oxidative aging effect, which triggered the deterioration of mechanical properties of PA10T/GF composites. Accordingly, the enhancement of rigidity were probably attributed to the higher temperature aging effect with the aging time prolonging in PA10T/GF composites, while the interfacial debonding between GF and resin matrix obviously occurred with the increase of aging time. In a word, it is believed that investigating the fundamental thermal-oxidative aging of PA10T/GF composites would be beneficial to optimize and control the service life and applications of materials. POLYM. ENG. SCI., 59:643-656, 2019. (c) 2018 Society of Plastics Engineers

关键词： benzamides   bi-heterocyclic   kinetics   molecular docking   phosphatase  

摘要： Novel bi-heterocyclic benzamides were synthesized by sequentially converting 4-(1H-indol-3-yl)butanoic acid (1) into ethyl 4-(1H-indol-3-yl)butanoate (2), 4-(1H-indol-3-yl)butanohydrazide (3), and a nucleophilic 5-[3-(1H-indol-3-yl)propyl]-1,3,4-oxadiazole-2-thiol (4). In a parallel series of reactions, various electrophiles were synthesized by reacting substituted anilines (5a-k) with 4-(chloromethyl)benzoylchloride (6) to afford 4-(chloromethyl)-N-(substituted-phenyl)benzamides (7a-k). Finally, the nucleophilic substitution reaction of 4 was carried out with newly synthesized electrophiles, 7a-k, to acquire the targeted bi-heterocyclic benzamides, 8a-k. The structural confirmation of all the synthesized compounds was done by IR, H-1 NMR, C-13 NMR, EI-MS, and CHN analysis data. The inhibitory effects of these bi-heterocyclic benzamides (8a-k) were evaluated against alkaline phosphatase, and all these molecules were identified as potent inhibitors relative to the standard used. The kinetics mechanism was ascribed by evaluating the Lineweaver-Burk plots, which revealed that compound 8b inhibited alkaline phosphatase non-competitively to form an enzyme-inhibitor complex. The inhibition constant K-i calculated from Dixon plots for this compound was 1.15 mu M. The computational study was in full agreement with the experimental records and these ligands exhibited good binding energy values. These molecules also exhibited mild cytotoxicity toward red blood cell membranes when analyzed through hemolysis. So, these molecules might be deliberated as nontoxic medicinal scaffolds to render normal calcification of bones and teeth.

关键词： Epoxy resin   Furfuryl alcohol   Curing kinetic   Furan hardener   Bio-additive  

摘要： Bio-resourced furan derivatives as additive (polyfurfuryl alcohol, PFA) and hardener (Difurfuryl amine, DFA) were synthesized then utilized in the preparation of the bio-based epoxy networks. The structural, thermal, thermomechanical, and mechanical properties and also the curing kinetics of the bio-based epoxy networks were investigated. FTIR and (HNMR)-H-1 corroborate the successful synthesis of the materials as well as the reaction between components. the mechanical properties of the networks such as tensile strength, Young's modulus, flexural strength and flexural modulus were ranging 10-16 MPa, 900-1100 MPa, 54-64 MPa and 3-4 GPa respectively. The curing kinetics was investigated by non-isothermal DSC and isoconversional methods to determine kinetic data and measurement of the activation energy. The applied models for the kinetic study were successfully fitted to the experimental data obtained from DSC. The results demonstrated the autocatalytic process of curing in samples. Also the activation energy of the curing process was ranging 50-80 KJ/mol.

关键词： Graphene  

摘要： The influence of functionalization of cyclohexyl diamine onto the graphene surface via diazonium reaction on the cure kinetics as well as morphology, mechanical, thermal and physical properties of natural rubber (NR)/graphene nanocomposite foam was investigated. The surface functionalization of graphene was confirmed by Fourier transform infrared spectroscopy, Raman spectroscopy, and thermogravimetric analysis (TGA). Without an addition of blowing agent, the vulcanized NR composites containing cyclohexyl amine-treated graphene showed not obvious different dispersion of graphene nanoplatelets than those containing untreated graphene as confirmed by transmission electron microscopy micrographs. Although the addition of untreated graphene could accelerate the sulfur vulcanization rate of NR nanocomposite foam due to the high thermal conductivity of graphene particle, and the remaining oxygen functional groups on the surface of graphene, the amines from cyclohexyl diamine on the treated graphene could react with carboxylic and epoxide group on the surface of graphene leading to a reduction of reactive oxygen functional groups on graphene surface and in turn slowed vulcanization rate. The fast vulcanization rate in untreated graphene system led to small bubble size in the NR nanocomposite foams. In contrast, the treated graphene system showed high tensile strength and low thermal expansion coefficient owing to low cell density. Finally, the defect on the graphene surface after functionalization was detected by Raman spectroscopy;this resulted in poor thermal conductivity for the treated graphene composite system. (C) 2018 Society of Plastics Engineers

关键词： Melamine formaldehyde microsphere   nitrile butadiene rubber   interaction   vulcanization   mechanical strength  

摘要： The melamine formaldehyde (MF) microsphere/nitrile butadiene rubber (NBR) vulcanizates were prepared by adding MF into NBR through mechanical mixing, followed by a vulcanization process. The influences of MF on the vulcanization characteristics, vulcanization kinetics, and mechanical properties were investigated. The results showed that MF interacted with NBR through hydrogen bonds. In addition, parameter b calculated by the ratio of modulus and strains also demonstrated the strong interaction between MF and NBR. Adding MF into NBR would reduce the curing time of NBR compounds, and increase the curing rate, as well as the cross-linked density. The vulcanization kinetics of MF/NBR compounds could be simulated accurately by Ghoreishy's model. The mechanical properties of MF/NBR increased with the incorporation of MF. The modulus at 100%, modulus at 300%, and tensile strength of NBR vulcanizates with 20 parts per hundred rubber MF had 155, 90, and 110% increment, respectively, compared with those of neat NBR. The MF also enhanced the tear strength of NBR by 80% with a rough tear-fractured surface of NBR recorded by scanning electron microscope.

关键词： Molecular dynamics simulation   Aluminum alloy   Zinc alloy additive   Mechanical properties of aluminum alloy   Large-Scale Atomic/Molecular Massively Parallel Simulator (LAMMPS)   Modified embedded atomic method  

摘要： We propose a potential model to represent aluminum 7075 alloys and use the model to analyze their mechanical behaviors under different strain rates at the molecular level. Although aluminum 7075 alloy has been used in various fields, a model that takes all the components of the alloy into consideration has not yet been proposed;thus, simulation at the molecular level has not yet been performed. Especially, as for the zinc, the modified embedded atomic method (MEAM) potential parameters were not available because the axial ratio of zinc is larger than 1. Our work overcomes this problem by proposing a potential model capable of considering all the elements comprising aluminum 7075 alloys. Our approach involves applying the verified embedded atom method (EAM), incorporating potential parameters of zinc to the MEAM potential parameters, and utilizing the existing MEAM potential parameters of the other elements. Using the proposed potential model, we created molecular dynamics models of aluminum 7075 alloys both with and without the consideration of zinc. The mechanical properties of the two models under different strain rates are compared, and the effects of considering zinc on the alloy are investigated. As a result, it is observed that the model that possesses zinc shows higher yield stress and ultimate tensile strength than the model that does not have zinc. Moreover, suppression of the partial dislocation is noticed when zinc is present. The inclusion of zinc enhances the strength by inhibiting partial dislocation. This proposed model will be useful to analyze the mechanical behaviors of other alloys containing zinc.