关键词： Cardiac resynchronization therapy   Left bundle branch block   Heart failure with preserved ejection fraction  

摘要： Cardiac resynchronization therapy (CRT) has revolutionized the care of patients with heart failure with reduced ejection fraction (HFrEF) and left bundle branch block (LBBB);some hypothesize that electrical resynchronization may also benefit patients with heart failure with preserved ejection fraction (HFpEF) and LBBB. We assessed the acute hemodynamic and mechanical impact of temporary LV pacing in 2 patients with HFpEF and LBBB and a "classic" pattern of echocardiographic dyssynchrony. LV pacing facilitated electrical resynchronization with acute resolution of mechanical dyssynchrony and improvements in invasively and non-invasively measured global cardiac function, due in part to shortening of the isovolumetric contraction period. (C) 2018 Elsevier Inc. All rights reserved.

关键词： Analytical dynamics   Unilateral constraint   Manifold with boundary   Frictional contact   Central or eccentric collision  

摘要： This study focuses on the development of a new formulation, which describes the dynamics of a class of mechanical systems involving a single contact with friction. The whole process is performed within the general framework of analytical dynamics. At the same time, the efforts are assisted and enhanced by employing some fundamental tools of differential geometry. This provides a strong theoretical foundation, allowing for a systematic and consistent application of Newton's law of motion to systems possessing configuration manifolds with boundary. The manifold boundary is first defined by using the unilateral constraint representing the contact event. Then, it is shown that the corresponding contact phase takes place inside a thin layer near this boundary, where the dominant dynamics is described by a suitable set of three ordinary differential equations. The explicit appearance of time in the formulation introduces a short but finite time scale, which permits the consideration of contact of any combination of mechanical bodies, including rigid and discretized deformable bodies. Finally, the study concludes with presentation of a selected set of examples. In all cases, emphasis is put on illustrating the basic steps of the analysis as well as on capturing and investigating phenomena arising during central or eccentric collision of bodies. (C) 2018 Elsevier Ltd. All rights reserved.

关键词： 船舶动力   噪声数据   数据分析   方法优化  

摘要： 常规船舶动力机械噪声数据分析采用构建数学模型的方法对噪声数据进行分析,针对频率大于15 k Hz的瞬时机械噪声数学模型无法提取信息,通常采用高斯定理特定值估算法进行分析,存在高频瞬时机械噪声分析精度较低的不足,为此提出船舶动力机械的噪声数据分析方法优化。引入噪声矢量数据场体系构建采集-处理-输出的整体框架,根据工作条件对矢量数据场相关参数进行选取;依托雅克·杜波切特计算理论对机械噪声数据进行优化计算,完成提出的船舶动力机械的噪声数据分析方法优化。试验数据表明,提出的优化方法较常规数据分析方法,在高频阶段提高分析精度22.45%,适合于对船舶动力机械噪声的分析。

关键词： 工程机械   液压系统   动力匹配   控制技术  

摘要： 随着科学技术的不断发展,液压机械传动工程在工程机械管理系统中占有重要地位。在提高工程机械效率同时还可降低能耗。本文就针对工程机械液压系统动力匹配及控制技术进行了探讨。

关键词： 俯卧位机械通气   重症肺炎   呼吸衰竭   血流动力学   血气分析  

摘要： 目的:探讨俯卧位机械通气对重症肺炎并呼吸衰竭患者血气分析指标、血流动力学的影响.方法:选择2015年11月至2017年10月入住我院ICU的51例重症肺炎合并呼吸衰竭患者均接受俯卧位机械通气治疗,分别于俯卧位(PP)前、PP后1h、PP后2h、仰卧位(SP)后1h、SP后2h检测并比较患者血流动力学指标[心率(HR)、呼吸频率、平均动脉压(MAP)、心排血量(CO)、中心静脉压(CAP)]和血气分析指标[酸碱度(pH值)、二氧化碳分压(PaCO2)、脉搏血氧饱和度(SaO2)、氧合指数(PaO2/FiO2)以及血氧分压(PaO2)].观察患者皮肤黏膜损伤、皮下水肿、血压下降、发热等不良反应的发生情况.结果:PP后1、2h以及SP后1、2h患者PaO2、PaO2/FiO2、SaO2均高于PP前,差异均有统计学意义(P<0.05),PP后1、2h以及SP后1、2h患者PaO2、PaO2/FiO2、SaO2两两比较,差异均无统计学意义(P>0.05);各时间点患者HR、呼吸频率、MAP、CVP、CO、pH值、PaCO2差异均无统计学意义(P>0.05).仅1例患者发生皮下水肿,1例血压下降,均自行好转.结论:俯卧位机械通气有利于改善重症肺炎并呼吸衰竭患者的PaO2、PaO2/FiO2、SaO2,且对血流动力学无明显影响,值得临床推广.

关键词： Polyurethane foam   Nanoclay   Nanosilica   Reaction kinetics   Thermal properties   Mechanical properties  

摘要： The use of functional nanofillers to improve the properties of rigid polyurethane (PU) foams has caused the need for a better understanding of how these nanofillers modify the reaction kinetic of the PU system. In this study, different nanoclays and nanosilicas are used as functional nanofillers. Analysis of the kinetic data obtained by in-situ FTIR spectroscopy monitoring allows to correlate the isocyanate consumption with the type of nanoparticles. The quantification of urethane and urea, obtained by deconvolution of the carbonyl region absorptions, enables to follow the blowing and gelling reactions during the foaming process. These reactions are correlated to the nature of the chemical groups present on the surface of the nanoparticles added. In addition, the effect of the modification of the reaction kinetics on the density, cellular structure, thermal conductivity and mechanical properties is herein discussed. (C) 2018 Elsevier Ltd. All rights reserved.

关键词： Thiols   Kinetic parameters   Vinyl   Functional groups   Kinetics  

摘要： Kinetic parameters and their influence on the overall rates of base-catalyzed thiolMichael reactions proceeding via an alternating propagation and chain transfer cycle were evaluated. A kinetic model was developed that enables the determination and accurate prediction of the reaction kinetic paths for the thiolMichael addition reaction and its accompanying polymerization. Individual kinetic parameters for propagation and chain transfer steps were evaluated for three commonly used thiol and vinyl functional monomers. Chain transfer and propagation kinetic parameters were determined in binary combinations of monomers from analysis of experimental data for the reaction rates. Subsequently, eight ternary thiolMichael systems composed of thiolacrylatevinyl sulfone and thiol 1-thiol 2-vinyl were analyzed based on the binary kinetic model parameters. It was clearly demonstrated that the kinetic parameters determined from the binary reactions enabled an accurate prediction of the relative reactivity and selectivity in the multicomponent systems. Finally, the calculated kinetic parameters were utilized in network-forming polymerizations to validate the suitability of the model to predict network development, particularly in the initial stages prior to any diffusion limitations on the reaction kinetics. These results serve as a useful guide for monomer selection in designing thiolMichael-based polymers with appropriate kinetic characteristics and material properties.

关键词： Montmorillonite   Complexation   Adsorption   Cations   Ions  

摘要： Systematic first-principles molecular dynamics (FPMD) simulations were carried out to study the structures, free energies, and acidity constants of UO22+ surface complexes on montmorillonite in order to elucidate the surface complexation mechanisms of the uranyl ion (UO22+) on clay mineral edges at the atomic scale. Four representative complexing sites were investigated, that is, Al(OH)(2) and AlOHSiO on the (010) surface and AlOHOa and SiOOa on the (110) surface. The results show that uranyl ions form bidentate complexes on these sites. All calculated binding free energies for these complexes are very similar. These bidentate complexes can be hydrolyzed, and their corresponding derived pK a values (around 5.0 and 9.0 for pK(a1), and pK(a2), respectively) indicate that UO2(OH)(+) and UO2(OH)(2) surface groups are the dominant surface species in the environmental pH range. The OH groups of UO2(OH)(2) surface complexes can act as complexing sites for subsequent metals. Additional simulations showed that such multinuclear adsorption is feasible and can be important at high pH. Furthermore, FPMD simulation results served as input parameters for an electrostatic thermodynamic surface complexation model (SCM) that adequately reproduced adsorption data from the literature. Overall, this study provides an improved understanding of UO22+ complexation on clay mineral edge surfaces.

关键词： 工程机械   混合动力工程   储能装置  

摘要： 储能装置对工程机械混合动力系统的安全运行和效率的提高均具有重要的影响。基于此,本研究在概述工程机械混合动力储能装置相关理论的基础上,重点介绍了液压蓄能器、超级电容、飞轮电池以及电化学电池混合动力储能装置,并比较了这四种储能装置的优缺点,以希望为混合动力储能装置在工程机械中的具体应用提供借鉴和指导。