北京地铁暗挖隧道注浆止水和加固技术分析

以北京地铁暗挖隧道施工为工程背景,结合当地地质条件,决定采取袖阀管深孔注浆和前进式注浆工艺相结合的施工方案对隧道周围土体进行加固,经数值分析可知加固效果较为显著,从而确保了隧道施工质量。     

风力驱动顶出装置的研制

简介了风力驱动顶出装置的研制情况,特别介绍了该装置的总体方案设计、结构组成、工作原理以及该装置的创新点。该装置使用风力来进行驱动,实现搬运货物或者其他功能,可以大大节约能源,更好的体现低碳环保。     

Risk factors associated with elevated serum pancreatic amylase levels during hemodialysis

Elevated levels of serum pancreatic enzymes are frequently observed in hemodialysis (HD) patients. The complex hemodynamic, biochemical, and physiological alterations in uremia were speculated to cause excessive release of pancreatic enzymes beyond decreased renal clearance. However, hemodynamic factors are seldom explored in this aspect. We performed the study to evaluate the association between intradialytic hemodynamic change and elevated serum pancreatic amylase (SPA). Eighty‐three prevalent HD patients without any clinical evidence of acute pancreatitis underwent pre‐HD and post‐HD blood sampling for serum pancreatic enzyme levels. Demographic, biochemical, and hematological data were collected from patient record review. Hemodialysis information including intradialytic blood pressure changes and ultrafiltration (UF) amount were collected and averaged for 1 month before the blood sampling day. Patients with elevated SPA during the HD session had greater mean systolic blood pressure and mean arterial pressure reduction, greater UF volume, greater pre‐HD blood urea nitrogen and serum creatinine, higher serum phosphorus, lower pre‐HD serum total CO₂, and lower left ventricle ejection fraction (LVEF). Using multivariate linear and logistic regression analysis, the independent predictors of elevated SPA were determined to be mean arterial pressure reduction during HD, mean UF amount, pre‐HD serum total CO₂, and LVEF. Greater blood pressure reduction during HD, greater UF volume, lower pre‐HD serum total CO₂, and lower LVEF were significantly associated with elevated SPA during HD. This suggests that hemodynamic factors contribute to elevated serum pancreatic enzymes in HD patients.     

Simulation and experiment study on adhesive ejection behavior in jetting dispenser

In this paper, fundamental equations for jetting dispenser are presented to express the influence of adhesive pressure, nozzle diameter, and needle movement law, and the equations are then verified by flow behavior simulation. Subsequently, a novel jetting dispenser system is built to finish experiments about the mentioned influence parameters, and simulation results verify the regularities from experiment are correct. Flow velocity in the central nozzle will be faster and radius of the droplet will be bigger if the pressure in the chamber became higher, flow velocity in the central nozzle will be constant and the radius of the droplet will be bigger if the dead time became longer, and bigger nozzle diameter can lead to faster flow velocity in the central nozzle and bigger droplet. Besides, these mentioned works prove that our designed jetting dispenser is practical and useful for adhesive jetting.     

SDG故障诊断方法在核动力装置中的应用研究

核动力装置运行状态的诊断关系到装置运行的安全性和可靠性。针对核动力装置系统复杂,难以建立数学模型的特点,本文将基于定性模型的符号有向图（SDG）方法应用于核动力装置中进行故障诊断,并以核动力装置主冷却剂系统为研究对象,提出了相应的建模方法并建立了SDG模型,根据所建立的模型开发了基于SDG方法的核动力装置故障诊断系统,并以蒸汽发生器传热管破裂（SGTR）事故和弹棒事故为例对该系统的诊断推理过程进行了分析。仿真结果表明,基于SDG的方法在核动力装置中能有效诊断故障,并能提供故障传播路径,具有良好的解释性,可为运行人员决策提供帮助。     

二维T-S波在壁面局部喷吸边界层流中的演化

采用壁面设置局部法向速度模拟喷吸条件,数值计算获得稳定的三维边界层基本流的数值解。在此基础上,研究不稳定的二维扰动T-S波在空间演化过程的非线性问题;探讨边界层壁面局部无量纲喷吸速度0.004,0.000 6对二维T-S波非线性演化的影响及其对增长率的贡献。数值计算结果表明,边界层平均流剖面的改变促进了扰动波的快速增长,增强了流体运动的不稳定性,扩大了中性曲线的不稳定区域范围,不稳定的二维T-S波获得了更大的增长率;不稳定的二维扰动T-S波在非线性演化过程中,由于非线性相互作用不断增强,逐渐诱导激发出三维扰动速度及高次谐波,其三维扰动基本波的流向波数和频率与二维扰动波的流向波数和频率相同;正、负相间流向涡及强剪切层已初步形成。     

手机外壳双色反向模具的顶出系统设计

设计了双色反向注塑模具,第一射模具的预压顶针系统和第二射的静模顶出系统是该双色反向模具的主要特点,通过设置工艺平面来避免浇口产生的痕迹和顶针压痕;并针对塑件的收缩,介绍了预压顶针和摩擦开闭器的脱模力计算方法;用Moldflow软件对双色成型进行了仿真和评估。试模结果表明,该双色反向注塑模具的设计成功避免了常规双色注射成型中产生的料花和流痕等缺陷,并保证了大批量生产的品质。     

灯罩塑件二次顶出结构及相关尺寸计算

介绍了对原有防尘灯罩注射模具的改进与其主要结构、工作原理和顶出机构的有关尺寸计算。     

深腔类注射模旋转顶出脱倒扣的装置

介绍了一种旋转顶出脱内倒扣的结构,此结构可应用在深腔类注射模无法通过斜顶脱倒扣的情况。洗碗机内胆模具属于典型的中大型深腔注射模,塑件底部有3个卡扣需要设计脱倒扣机构实现出模。由于模具型芯高度太高,常规斜顶需要做到600mm以上且截面积小于10×10mm,斜顶在模具使用过程中极易弯曲或折断。该结构通过固定在顶出板上的轴承座以及旋转控制导轨实现顶出-旋转-顶出的动作,使塑件脱离倒扣,代替了传统斜顶。此机构可以提高模具寿命,降低维护成本。     

高压弹射装置内弹道二维模型及发射腔内流场特性分析

高压弹射装置中火药先燃烧积聚成高压气体,后瞬间打开,弹射弹丸攻击目标。为了掌握这一过程中发射腔内流场的复杂变化,建立了高压弹射装置内弹道二维气相模型,采用Runger-Kutta算法和MacCormark差分格式耦合方法进行数值模拟,并将计算所得的压力曲线与试验结果进行对比,验证了数值计算的可靠性。进一步根据计算得到发射腔内气体压力、速度等参量的分布情况,分析发射腔内的流场特性。结果表明,弹射关键阶段在弹丸启动的较短时间内,高压气体大小和分布是影响弹丸弹射效果的直接因素。