四君子汤对小鼠抗疲劳耐缺氧作用的研究

观察四君子汤对小鼠抗疲劳、耐缺氧能力的影响,并探讨其作用机理.方法:用水提醇沉法制得四君子汤.取小鼠160只,随机分成Ⅰ、Ⅱ、Ⅲ、Ⅳ四组,Ⅰ和Ⅲ组灌胃、Ⅱ和Ⅳ组腹腔注射四君子汤.各处理组给药浓度分别为0.5g/mL、1.0g/mL、1.5g/mL,给药量均为0.2mL/10g,对照组给予等量生理盐水.连续6天,在最后一次给药30min后,进行负重游泳及耐缺氧试验,测定小鼠的存活时间.结果:在耐缺氧试验中,腹腔注射高剂量(1.5g/mL)四君子汤作用效果明显(P＜0.05),其他各处理组小鼠在不同的抗应激试验中生存时间均比对照组延长,但差异不显著(P＞0.05).结论:灌胃和腹腔注射四君子汤水提醇沉液对小鼠均有一定的抗疲劳和耐缺氧作用.     

Experimental Study on Force Behavior of Steel Reinforced Concrete Transfer Beam Structure with Basement of Large Space *

本文通过转换梁及其下部柱中设与不设型钢骨架两种方案托柱式底层大空间转换层结构模型的对比试验,系统研究了其在垂直荷载和水平荷载作用下的受力性能、位移延性和破坏机制等．结果表明：型钢混凝土转换梁结构具有良好的受力及抗震性能,并提出了有关设计建议．     

成层地基半透水边界一维固结分析

本文在Terzaghi模型基础上,考虑了半透水边界条件和逐渐加荷条件,求解出一维固结解,并根据该解详细研究了成层土有别于单层土的一些固结特性以及半透水边界、土层性质、加荷速率等对超静孔压及地基固结度的影响,并通过算例说明了解的应用。     

饱和砂土自由场地地震液化的离散元模拟

为研究饱和砂土自由场地的地震液化过程,基于颗粒离散元与计算流体动力学耦合方法,在PFC3D程序中通过二次开发实现对自由场地基底不规则地震波的输入,研究在实测Kobe地震波激励下该液化过程的宏细观力学响应,并与已有的福建中细砂离心机模型试验结果进行对比。数值模拟结果表明:试样发生液化的时刻对应于基底地震加速度峰值时刻,浅部土层先于深部土层发生液化,超静孔隙水压力的消散是从深部土层逐渐向浅部土层发展的;伴随液化过程,各深度土层的有效应力路径均从初始应力状态向应力空间的原点移动;数值试验呈现出的上述规律均与实际砂土离心机模型试验呈现出的规律保持一致。数值试样宏观的液化特征在微观机理上可由流体对颗粒的归一化拖曳力、局部孔隙比、平均配位数、颗粒位移的变化规律来相应表征。     

船舶港口装卸过程中波浪补偿的数值方法

为提高船舶港口装卸效率,实现港口装卸自动化, 利用数值波浪水池模拟船舶港口装卸工程中的波浪补偿问题.基于CFD理论建立船舶港口装卸过程中波浪补偿数值计算模型.通过Flow 3D的边界造波模块,建立三种不同波形的数值波浪水池,并配合Sommerfeld辐射边界条件以及多孔介质模型进行消波.结合CAD技术对船舶港口装卸过程中的波浪补偿进行数值分析,最终将该船舶港口装卸过程中的波浪补偿量转化为起重机的位移补偿量.仿真结果表明,该方法满足工程要求,可为港口自动化装卸提供技术支持.     

Between-limb asymmetry in kinetic and temporal characteristics during bilateral plyometric drop jumps from different heights

ABSTRACT

This study investigated the between-limb asymmetry in kinetic and temporal characteristics during bilateral plyometric drop jumps from different heights. Seventeen male basketball players performed drop jumps from 3 heights on two platforms in randomized orders. Vertical ground reaction force data were analysed with respect to the lead limb (i.e. the limb stepping off the raised platform first) and trail limb. Peak forces and loading rates of each limb were calculated. The absolute time differential between the two limbs at initial ground contact and takeoff were determined. The frequency of symmetrical landing and taking off with “both limbs together” were counted using 3 time windows. Results showed that the lead limb displayed higher peak forces and loading rates than the trail limb across all heights (p <.05). As drop height increased, the absolute time differentials decreased at initial ground contact (p <.001) but increased at takeoff (p =.035). The greater the preset time window, the more landings and takeoffs were classified as bilaterally symmetrical. In conclusion, higher drop heights allowed subjects to become more bilaterally symmetrical in the timing of landing but this reduction in temporal asymmetry did not accompany with any reduction in kinetic asymmetry.     

焊接高强箍筋高强混凝土柱滞回特性研究

以2根焊接高强箍筋、高强混凝土柱试件为研究对象,进行低周反复水平荷载作用试验,研究体积配箍率的变化对柱滞回特性的影响.试验结果表明,高强混凝土柱体积配箍率较大的试件滞回曲线相对饱满,滞回环面积较大,累积滞回耗能大,吸收地震能量多,延性好.该研究结果对发展应用高强混凝土具有实际意义.     

On the Exploratory Road to Unraveling Factor Loading Non-invariance: A New Multigroup Rotation Approach

Multigroup exploratory factor analysis (EFA) has gained popularity to address measurement invariance for two reasons. Firstly, repeatedly respecifying confirmatory factor analysis (CFA) models strongly capitalizes on chance and using EFA as a precursor works better. Secondly, the fixed zero loadings of CFA are often too restrictive. In multigroup EFA, factor loading invariance is rejected if the fit decreases significantly when fixing the loadings to be equal across groups. To locate the precise factor loading non-invariances by means of hypothesis testing, the factors’ rotational freedom needs to be resolved per group. In the literature, a solution exists for identifying optimal rotations for one group or invariant loadings across groups. Building on this, we present multigroup factor rotation (MGFR) for identifying loading non-invariances. Specifically, MGFR rotates group-specific loadings both to simple structure and between-group agreement, while disentangling loading differences from differences in the structural model (i.e., factor (co)variances).     

在役混凝土拱桥承载能力的鉴定与评估

为检验在役混凝土拱桥的承载能力与动力特性,对某净跨为134.7m的拱桥进行荷载试验。测试结构静态的应变、桥面挠度、拱肋挠度、吊索变形、吊索索力等结构静力反应。同时,测试了结构自振频率、动挠度及加速度等结构动力反应,根据动挠度计算得出冲击系数。将实测值与理论值进行对比分析。结果表明,应变校验系数在0.7～1.0之间,实测的挠度、吊索索力、频率及冲击系数均小于理论值,说明桥梁具有较好承载力和整体竖向刚度较好。试验方法与分析结果为今后评估与鉴定同类型桥梁提供理论依据和技术参考。     

基于堆场混堆的集装箱异贝位同步调度方法

针对集装箱码头内装卸桥、集装箱卡车与龙门吊三者对集装箱装卸问题,基于现今码头同步装卸技术的思想,在深入分析研究该项技术在集装箱装卸调度方法的实际应用基础上,结合集装箱贝位协同作业的同步装卸方法,提出了基于堆场混堆的集装箱异贝位同步调度方法,建立了集装箱卡车总行驶距离最小的数学模型,并运用单亲遗传算法对模型进行求解.运用Matlab进行数值模拟,对比传统单程装卸模式的数据,验证了基于堆场混堆的集装箱异贝位同步调度方法的可行性与有效性.