轮式车辆动力传动系统动态特性键合图建模与仿真的研究

在深入分析车辆纵向运动时动力传动系统各单元动态特性及其相互作用的基础上，运用键合图理论构造了车辆动力传动系统较完整的动态模型，并用实例进行了仿真和试验验证。研究结果表明，所建模型和仿真可以较准确地反映系统的动态特性。     

双层套管井中声波波形分析

用柱状多层理论模型,计算了裸眼井、单层套管井、双层套管井中的声波波形。分别用地层纵波、横波和套管波信息,结合三种模型对双层套管井中不同条件下水泥胶结质量进行了详细分析。指出用内层套管波列和地层波列可定性判断两层套管之间的水泥胶结质量,用外层套管波列和地层波列能判断外层套管和地层之间的水泥胶结质量。结果表明,裸眼井和套管井的声波全波资料综合分析,能较好地评价水泥胶结质量。     

镀铜钢纤维表面改性及其耐腐蚀性能和黏结性能

为了改善镀铜钢纤维与水泥基体的黏结强度,用γ-甲基丙烯酰氧基丙基三甲氧基硅烷(MPS)和γ-巯基丙基三甲氧基硅烷(MPTS)对镀铜钢纤维进行表面处理.采用红外光谱、扫描电子显微镜(SEM)、氯化钠溶液浸泡腐蚀试验和黏结强度测试来评价处理后镀铜钢纤维的性能.结果表明:MPTS与镀铜钢纤维表面发生了化学键合,提升了钢纤维表面粗糙度;经过MPS处理和MPTS/MPS组合处理的钢纤维腐蚀溶液的吸光度积分只有未处理组的91%和45%;经过MPS处理和MPTS/MPS组合处理的钢纤维从水泥基体中拔出时所做的功相对于未改性组分别提升了43%和224%,与水泥基体的黏结强度得到了相应提高.     

The bond graph model of planar flexible multibody mechanical systems and its dynamic principle

Toincreasethereliabilityandefficiencyofthedy namicanalysisofflexiblemultibodysystems,differentprocedureshavebeenproposedinpreviousworks[1,2].Buttheseproceduresareonlysuitableforasingleener gydomain,suchasastrictmechanicalone,andcan notdealwiththeproblemsofcomputeraideddynamicanalysisofplanarflexiblemultibodymechanicalsys temscontainingthecouplingofmulti energydomains.Bondgraphs[3]havepotentialapplicationsinanalyzingsuchcomplexsystemsbecauseoftheirabilitytode scribethedynamicsofinteractingsyste…     

Influence of priming time and primer’s concentrations on bovine enamel bond strengths

This study investigated the effects of priming time (5, 30 or 60?s), 10-MDP (10-methacryloyloxydecyl dihydrogen phosphate)-containing primer’s concentrations (0.5, 1, 5, 10 and 20% (w/w)) and two neutral primers (5% (w/w) of 10-MDP-Na or EDTA-2Na) on bovine enamel microtensile bond strength (μTBS) using a novel prime-and-rinse approach. After priming, the enamel surfaces were thoroughly water-sprayed and dried before resin composite was placed. There was a significant influence of primer’s concentrations and priming time on bovine enamel μTBS when 10-MDP-containing primers were used (p?<?0.001), revealing the optimal priming time (30?s) and the best combination (priming with 20% of 10-MDP for 30?s). The prime-and-rinse approach might be an innovative supplement to contemporary dental adhesive procedures. The neutral primer (5% of 10-MDP-Na) produced moderate enamel μTBS on highly polished enamel surfaces, while another neutral primer (5% of EDTA-2Na) failed, suggesting that chemical bonding of 10-MDP to enamel hydroxyapatite crystallites could yield detectable bond strengths on smooth enamel surfaces.     

静电纺丝法制备含四重氢键的聚氨酯纳米纤维

合成了含四重氢键UPy单元的聚氨酯,该四重氢键体系在非极性溶剂CHCl3中能通过四重氢键识别发生自聚作用,溶液黏度可大大提高,有利于静电纺丝的顺利进行,可降低最低可纺浓度。从溶剂配比和纺丝液的浓度两方面初步探讨了该聚氨酯的静电可纺性:φ(DMF)/φ(CHCl)3=1/1为该体系的最佳溶剂配比;当聚氨酯的质量分数为8%~12%时,可以顺利得到聚氨酯纳米纤维。     

基于因果行为模型的机械运动系统方案求解

从机械运动系统的多能复合特征出发,提出了基于因果行为模型的方案求解方法.采用键合图建模运动行为语义,提取了输入输出的能量类型、变化与约束特征.通过有向图联结基本行为,建立因果行为模型来描述系统的复杂行为.建立了相应的方案求解过程模型,其中方案创新主要通过正向推理组合基本元件,方案变型则通过在约束下扩展行为模板实现.最后,以工业高速平头锁眼机运动方案为例,验证了该方案的可行性.     

镧系、锕系元素化合物Δ_fH_m~Θ与结构的相关性

根据 Randic分子连接性拓扑理论 ,建立了一个新的键参数——拓扑指数 YM,并用 YM对 1 50余种镧系、锕系元素化合物的标准生成焓 -Δf HΘm 拟合 ,结果相关性良好。     

Physicochemical and Theoretical Characterization of a New Small Non-Metal Schiff Base with a Differential Antimicrobial Effect against Gram-Positive Bacteria

Searching for adequate and effective compounds displaying antimicrobial activities, especially against Gram-positive bacteria, is an important research area due to the high hospitalization and mortality rates of these bacterial infections in both the human and veterinary fields. In this work, we explored (E)-4-amino-3-((3,5-di-tert-butyl-2-hydroxybenzylidene)amino) benzoic acid (SB-1, harboring an intramolecular hydrogen bond) and (E)-2-((4-nitrobenzilidene)amino)aniline (SB-2), two Schiff bases derivatives. Results demonstrated that SB-1 showed an antibacterial activity determined by the minimal inhibitory concentration (MIC) against Staphylococcus aureus, Enterococcus faecalis, and Bacillus cereus (Gram-positive bacteria involved in human and animal diseases such as skin infections, pneumonia, diarrheal syndrome, and urinary tract infections, among others), which was similar to that shown by the classical antibiotic chloramphenicol. By contrast, this compound showed no effect against Gram-negative bacteria (Klebsiella pneumoniae, Escherichia coli, and Salmonella enterica). Furthermore, we provide a comprehensive physicochemical and theoretical characterization of SB-1 (as well as several analyses for SB-2), including elemental analysis, ESMS, ¹H and ¹³C NMR (assigned by 1D and 2D techniques), DEPT, UV-Vis, FTIR, and cyclic voltammetry. We also performed a computational study through the DFT theory level, including geometry optimization, TD-DFT, NBO, and global and local reactivity analyses.