Numerical Investigation of Electrohydrodynamic (EHD) Flow Control in an S-Shaped Duct

An electrohydrodynamic （EHD） method, which is based on glow discharge plasma, is presented for flow control in an S-shaped duct. The research subject is an expanding channel with a constant width and a rectangular cross section. An equivalent divergence angle and basic function are introduced to build the three-dimensional model. Subsequently, the plasma physical models are simplified as the effects of electrical body force and work （done by the force） on the fluid near the wall. With the aid of FLUENT software, the source terms of momentum and energy are added to the Navier-Stokes equation. Finally, the original performance of three models （A, B and C） is studied, in which model A demonstrates better performance. Then EHD control based on model A is discussed. The results show that the EHD method is an effective way of reducing flow loss and improving uniformity at the duct exit. The innovation in this study is the assessment of the EHD control effect on the flow in an S-shaped duct. Both the parametric modeling of the S-shaped duct and the simplified models of plasma provide valuable information for future research on aircraft inlet ducts.

Correlation of annexin A2 expression with epithelial-mesenchymal transition and extracellular matrix degradation in bile duct carcinoma

Objective: To investigate the correlation of annexin A2 expression with epithelial-mesenchymal transition (EMT) and extracellular matrix (ECM) degradation in bile duct carcinoma. Methods: A total of 60 patients with primary bile duct carcinoma who accepted bile duct carcinoma laparotomy in our hospital between April 2009 and May 2017 were selected. The bile duct carcinoma tissue and adjacent normal tissue were kept during operation and enrolled in bile duct cancer group (n=60) and normal control group (n=60). The protein expression of annexin A2, EMT marker molecules, MMPs subtypes and TIMPs subtypes in two groups of specimens were detected, and Pearson test was used to evaluate the correlation of annexin A2 expression with EMT and ECM degradation in bile duct carcinoma tissue. Results: Annexin A2 expression in bile duct cancer group was higher than that in normal control group;E-cadherin, β-catenin and syndecan-1 protein expression in bile duct cancer group were lower than those in control group whereas P-cadherin and Vimentin protein expression were higher than those in normal control group;MMP-2, MMP-7 and MMP-9 protein expression in bile duct cancer group were higher than those in normal control group whereas TIMP-1 and TIMP-2 protein expression were lower than those in normal control group. Pearson test showed that the annexin A2 expression in bile duct carcinoma was directly correlated with the protein expression of EMT marker molecules, MMPs subtypes and TIMPs subtypes. Conclusion: annexin A2 increases in bile duct carcinoma, and it can regulate EMT and ECM degradation process to affect the disease outcome.

Targeting tight junctions during epithelial to mesenchymal transition in human pancreatic cancer

Pancreatic cancer continues to be a leading cause of cancer-related death worldwide and there is an urgent need to develop novel diagnostic and therapeutic strategies to reduce the mortality of patients with this disease. In pancreatic cancer, some tight junction proteins, including claudins, are abnormally regulated and therefore are promising molecular targets for diagnosis, prognosis and therapy. Claudin-4 and-18 are overexpressed in human pancreatic cancer and its precursor lesions. Claudin-4 is a high affinity receptor of Clostridium perfringens enterotoxin(CPE). The cytotoxic effects of CPE and monoclonal antibodies against claudin-4 are useful as novel therapeutic tools for pancreatic cancer. Claudin-18 could be a putative marker and therapeutic target with prognostic implications for patients with pancreatic cancer. Claudin-1,-7, tricellulin and marvelD3 are involved in epithelial to mesenchymal transition(EMT) of pancreatic cancer cells and thus might be useful as biomarkers during disease. Protein kinase C is closely related to EMT of pancreatic cancer and regulates tight junctions of normal human pancreatic duct epithelial cells and the cancer cells. This review focuses on the regulation of tight junctions via protein kinase C during EMT in human pancreatic cancer for the purpose of developing new diagnostic and therapeutic modalities for pancreatic cancer.

Transition to adulthood: A critical role for exercise in building overall well-being

A growing number of multidisciplinary studies have reported the beneficial effects of physical activities towards the development of overall well-being and the reduction of chronic illnesses. Physical inactivity is a serious worldwide problem and is considered the key lifestyle factor that negatively influences health and function of individuals. Here we propose that growth kinetics of body and mind and associated disproportionate physical activity may have considerable effects on the increased physical and mental illnesses and premature death rates currently observed in mid to late adulthood people. Children and young adults, being in exponential growth phase and self-motivated to engage in physical activity, possess more cognition, resilience, and mind-body-emotion-spirit integration. In contrast, as our body transitions into adulthood, there is a decline in the growth of body and mind. Furthermore, in this period, adults experience the increased stressors of career and financial demands, time pressure, and family responsibilities. The decline in growth combined with prolonged stress appears to result in reduced cognition, resilience, and mind-body-emotion-spirit integration, leading to sedentary and other faulty lifestyles, which could further lead to a predisposition to maladaptive behaviours and various chronic diseases at a later stage. In agreement with this, currently more than two thirds of the adult population across the world are physically inactive and are failing to perform the daily recommended guidelines of moderate to vigorous exercise. As negative changes and faulty lifestyles begin to occur during and after adulthood transition, creating awareness in people between 29 to 35 years of age about mindful exercise should be considered a national priority. This would allow adults to achieve overall well-being, and increased productivity and life expectancy, reducing health care-associated economic burden placed on the nation.

RESEARCH ON SCHEME OF HIGH-SPEED ROTOR／WING TRANSITION HELICOPTER RD15

To analyze the existing schemes of high-speed rotorcrafts and some new technologies, a new conceptual sketch of the high-speed rotor/wing transition helicopter RD15 is proposed. The overall layout of the RD15 is given out and the transition process from the helicopter mode to the airplane mode is designed. The lift system consists of a circular disk-wing with four retractable blades. The technology of individual blade control is adopted for flight control in hover and low speed flight. The tail is a vectored thrust duct propeller. It can provide the anti-torque in hover, and offer the multi-directional controls and propulsion drive for the airplane mode flight. The aerodynamic characteristics and key technologies in the transition process for this layout, including the nose up angle of disk-wing, the length of the blade, rotation speed, pitch angle and other parameters, are theoretically ana lyzed and experimentally tested. Calculation and experiments show that the shift process of the lift, the power and controls are smooth, and the designed scheme is feasible.

Optimization of endwall contouring in axial compressor S-shaped ducts

This paper presents a numerical investigation of the potential aerodynamic benefits of using endwall contouring in a fairly aggressive duct with six struts based on the platform for endwall design optimization.The platform is constructed by integrating adaptive genetic algorithm（AGA）, design of experiments（DOE）, response surface methodology（RSM） based on the artificial neural network（ANN）, and a 3D Navier–Stokes solver.The visual analysis method based on DOE is used to define the design space and analyze the impact of the design parameters on the target function（response）.Optimization of the axisymmetric and the non-axisymmetric endwall contouring in an S-shaped duct is performed and evaluated to minimize the total pressure loss.The optimal ducts are found to reduce the hub corner separation and suppress the migration of the low momentum fluid.The non-axisymmetric endwall contouring is shown to remove the separation completely and reduce the net duct loss by 32.7%.

UHPC预制轨顶风道装配化研究

为提高轨顶风道现场施工的便捷性和施工质量,结合广州地铁10号线的实际情况,提出一种装配式轨顶风道的装配方案。结合使用超高性能混凝土(UHPC),利用其超高的力学性能和耐久性能,减少轨顶风道后期的相关维护。结果表明:本文所提出的装配式轨顶风道设计方案安全可靠,施工工艺合理,UHPC在预制风道中的使用,提高了风道的相关力学性能,降低了后期维护成本。

大型燃气轮机余热锅炉进口烟道速度均匀性研究

通过对燃气轮机出口与锅炉本体进口之间过渡烟道的数值模拟 ,得出不同仰角上面板烟道出口的速度分布。根据出口速度均匀性 ,确定了最佳仰角。此外 ,对非均速进口气流流经锅炉管束时的流场也进行了数值模拟 ,结果表明 :大约经过 4～ 5排管子 ,主气流速度即趋于均匀。在管箱顶部和底部 ,存在局部高速区 ,易造成管子磨损。这些结论已用于燃机余热锅炉的设计 ,并取得良好效果 ,使烟气均匀性问题得到解决。

燃气轮机余热锅炉过渡烟道的优化设计

针对余热锅炉过渡烟道内烟气流通截面的形式,给出了改变烟道上面板仰角和在烟道内加装导流板两种优化方案,并且通过对优化方案的模拟计算,得出了烟气速度在烟道出口截面上的分布情况。在对模拟结果的分析讨论后,得出两个优化方案的最佳选择。计算结果表明,加装导流板能够明显改善烟道出口截面的烟气速度分布,平均速度由11.13m/s增加到11.51m/s,速度的均方差由12.33m/s降为4.02m/s。将所得结论应用于实际工程中,取得了良好效果。

高涵道比发动机涡轮过渡流道性能模拟

采用数值模拟方法对高涵道比发动机涡轮过渡流道设计工况和非设计工况性能进行了详细分析,得出了与实验值较吻合的计算结果。数值结果与实验数据比较表明:所选的计算模型是可靠的,能够直接用来对带整流支板的涡轮过渡流道数值模拟;可以采用较紧凑的设计而得到对高压涡轮出口条件不敏感的低损失系统。

整体式固体火箭冲压发动机转级过程数值仿真

为了研究整体式固体火箭冲压发动机从助推级向冲压发动机级的工况转换(转级)过程,采用双时间步推进方法,求解非定常、三维、有化学反应的Navier-Stokes方程组,得到了发动机进气道/燃烧室一体化流场在转级过程中的变化情况,分析了相关因素对转级过程的影响。仿真研究表明,进气道出口堵盖打开前,进气道内气流保持压力振荡状态,振荡频率主要与飞行高度相关;堵盖打开后,空气与一次燃气进入补燃室掺混并燃烧,过程中发动机内流场发生剧烈的变化;堵盖打开时燃烧室内的压力对于进气道的起动至关重要。上述研究对于整体式固体火箭冲压发动机设计具有指导意义。

燃机过渡烟道尿素热解工艺的可行性研究

通过分析燃气轮机(燃机)过渡烟道内的烟气参数和烟气特性,以及尿素热解所需的条件,论证了利用燃机过渡烟道进行尿素热解的可行性,并提出了相关的设计参数。尿素热解雾化液滴中的最大粒径约180μm时,热解炉可正常运行。当燃机过渡烟道具有合适的温度、适当的雾滴粒径,满足停留时间和热解所需时间时,可保证尿素热解制氨,从而节省大量能源,使脱硝过程更加安全、经济、有效。

交叉三角形波纹板流道在过渡流状态下的传热与阻力特性

交叉三角形波纹板流道中流动常处于过渡态。本文研究了交叉波纹板中的周期性完全发展流动及热传递。利用周期性降低几何流道的复杂性以及简化模拟对象。为了模拟这个拓扑结构中的过渡流,利用了已经验证的低雷诺数k-ε,湍流模型来说明流动中的湍流流动。得到了三维复杂计算区的温度、速度以及湍流场。计算了在恒壁温和恒热流密度两种边界条件下的摩擦系数和平均Nusselt数及其与雷诺数的关系。湍流中心从上层壁面的波纹处移向下层壁面的波纹处并逐步增强。

垂直起降固定翼飞翼布局无人机过渡飞行纵向稳定性研究

针对由两个主涵道风扇和一个前涵道风扇组成垂直升力部件的垂直起降固定翼飞翼布局无人机,估算出风扇推力和喷流/机翼的诱导气动力,考虑到过渡飞行过程的气动干扰明显和配平控制量变化较大的影响,并且为了防止无人机进入失效陡壁,提出一种预置飞行迎角加速到安全速度后,先关闭主涵道再关闭前涵道风扇的过渡飞行控制策略,分析了无人机平飞速度、涵道风扇入口来流、出口喷流对配平和过渡飞行纵向稳定性的影响,得到了涵道风扇的作用减小了过渡飞行的短周期稳定性、增加了长周期的阻尼的结论。

胆汁淤积致肝内胆管上皮细胞间质表型转变的病理学分析

目的探讨胆汁性肝纤维化时胆管上皮细胞发生间质表型转变的特点。方法制作胆管结扎所致大鼠肝纤维化模型,利用HE染色、免疫组化和免疫荧光等方法,检测术后1周和2周时肝内胆管细胞的上皮和间质标志物的表达情况。结果大鼠胆管结扎后胆汁淤积,引起肝内汇管区胆管细胞显著增生以及围胆管成纤维细胞和纤维基质增加。免疫组化结果显示,假手术组和胆管结扎组大鼠胆管细胞均表达上皮细胞标志蛋白CK19,但胆管结扎组肝内胆管细胞也表达间质细胞标志物Vimentin和FSP1/S100A4。胆管结扎1周时,汇管区内新生小胆管呈Vimentin强阳性,2周时增生胆管周围许多细胞也呈Vimentin阳性。但两组大鼠胆管细胞均不表达肌成纤维细胞标志物α-SMA,α-SMA阳性细胞主要分布于汇管区胆管细胞周围。结论在胆汁性肝纤维化进程中胆管细胞增生并发生一定程度的上皮-间质表型转变,可能促进了肝纤维化的发生。

城市轨道交通车辆数字仿真分析管理平台设计

针对城市轨道车辆集成度高、结构复杂、开发周期长、试验成本巨大等特点,提出了应用虚拟产品开发技术,构建基于异地网络的分布式计算和协同设计的城市轨道车辆多学科数字化仿真分析和数据管理平台。该平台实现了车辆主要零部件、整车和列车系统的相关数字化设计、性能仿真和虚拟试验等分析研究工作,为城市轨道车辆产品设计人员提供易于操作的专业化CAE集成仿真分析和数据管理工具,可缩短产品设计周期、降低开发成本、提高产品竞争力。

排气弯管结构参数对回流环形燃烧室出口温度分布的影响

本文采用标准k-ε湍流模型进行弯管准三维轴对称和三维数值模拟,研究弯管几何结构对回流环形燃烧室出口温度分布的影响。结果表明,弯管中心轴线长度和进出口面积收敛比对出口温度分布有重要的影响,压力损失系数的影响次之。得到了弯管进出口温度分布系数的比值与压力损失系数、无量纲中心轴线长度和进出口面积收敛比的函数关系,所得结果可为满足出口温度分布系数的回流环形燃烧室排气弯管结构的优化设计提供有用的依据。

E^3对转涡轮设计特点分析(Ⅱ)——过渡段不同方案的流场分析比较

本文以E3对转涡轮方案为背景,针对高压涡轮动叶设计难以满足低压涡轮预旋需求的难点,提出了取消低压涡轮导叶,改由过渡段支板弥补高压涡轮所提供预旋不足的过渡段改进设想。对过渡段支板不同改进方案和E3原方案进行了流场计算、气动性能比较及结构可行性分析。

城市轨道交通车辆的一种新型线槽预布及安装工艺

简单介绍了德国西门子公司城市轨道交通车辆的线槽预布及安装工艺。详细介绍了株洲电力机车有限公司目前使用的城市轨道交通车辆车内线槽、底架线槽的预布及安装新工艺和操作过程,并将株洲电力机车有限公司的线槽安装工艺与国外同类企业的线槽安装工艺进行了对比分析。

中心线变化规律和膨胀比对圆转方过渡段流场形态的影响

为了获得流道中心线变化规律和截面膨胀比ε对圆转方过渡段流场形态的影响规律,在某型发动机的真实工况下,分别对3种中心线变化规律(前缓后急、缓急相当、前急后缓)和5种膨胀比(1.00,1.01,1.03,1.05,1.07)的圆转方过渡段结构进行建模计算,得到了圆转方过渡段内部流场形态、总压恢复系数和流向涡涡量的变化规律。结果表明:不同结构的横截面静压和速度分布差异较大。前急后缓结构在圆转方横截面出现明显的角涡;在三种中心线变化规律结构中总压恢复系数沿流向均呈下降趋势,流向涡涡量沿流向均呈先增大后减小的趋势,三种结构的流向涡涡量最大值从大到小依次为前急后缓结构、前缓后急结构和缓急相当结构,最大最小值相差19%。随着膨胀比的增大,在圆转方横截面会出现角涡;在不同膨胀比结构中总压恢复系数沿流向均呈下降趋势,流向涡涡量沿流向均呈先增大后减小的趋势,膨胀比1.03结构的局部流向涡无量纲涡量比1.07结构小40.9%。缓急相当中心线变化规律和膨胀比ε=1.03为最佳结构参数。