双模态超燃冲压发动机点火方案对比试验

在来流马赫数2、总温840K的双模态超燃冲压发动机扩张型燃烧室的冷启动工况下,对凹腔上游的煤油横向射流喷雾的三种点火方案(热射流点火、乙烯引导点火、凹腔内局部补氧点火)进行了试验对比研究。采用高速相机拍摄了不同点火方式下的初始火焰生成和发展过程,对比分析了各种点火方案的点火接力过程和压力响应特点。试验研究表明,热射流火焰和喷雾下游掺混燃烧后通过火焰逆传形成凹腔驻留火焰,室压受热射流供应及其与喷雾作用的非定常特性的影响较大;乙烯引导点火受乙烯燃烧强度的影响,在研究的参数范围内,由于生成的乙烯火焰较弱,易被煤油喷雾浇熄,旨在凹腔内形成接力火焰的点火方法未能实现乙烯引导的成功点火;在凹腔内局部补氧能够改善煤油喷雾的点火性能,点火接力过程过渡平稳。      

聚乙烯在固体燃料冲压发动机中燃烧特性的数值研究

为准确模拟聚乙烯在固体燃料冲压发动机中的燃烧状态,估算了乙烯-空气两步反应中,相关组分的粘性、导热系数随温度的变化,并进行多项式拟合;同时使用UDF进行质量、动量、能量添加。数值计算的结果表明:燃面退移速率的计算误差不超过11.3%,其变化规律与已有实验相同;补燃室温度的误差不大于5.2%;补燃室温度随来流空气质量流率的增大而减小;高来流空气总温或低来流空气质量流率的工况下,燃料充分燃烧所需的补燃室更长;几何相似,其它条件相同时,小尺寸发动机内流场传向燃料表面的热流密度更大,燃面退移速率更高。      

基于可拓学理论的冲压发动机传感器选型研究

依据已建立的亚燃冲压发动机一体化模型,采用可拓学理论中物元与关联函数的概念,将亚燃冲压发动机传感器选型中各个因素间的关系转化成关联函数矩阵,运用层次分析法确定各个因素的权重值,提出一种应用于亚燃冲压发动机传感器选型的综合评价方法。通过对亚燃冲压发动机燃烧室进口温度传感器选型的验证,表明此方法与工程实践相结合,可行性较高。      

陈宥成:目标有多大,市场有多大

香港南明美容集团陈宥成总经理的办公室，坐落在北京玲珑公园个幽静的四合院内。在这个幽雅的环境中，陈宥成显得非常健谈。     

主成份投影法用于多目标决策与评价

提出了一种多目标决策与评价的新方法——主成份投影法。该方法概念清楚,涵义明确,本质上是一种加权方法,但与其它一些加权方法并非完全一致,且具有不同的经济涵义和数学涵义。     

早期目标指导的容量治疗防治重症急性胰腺炎腹腔高压和多脏器功能不全的作用

目的 探讨早期目标指导的容量治疗中使用6%羟乙基淀粉130/0.4氯化钠注射液防治重症急性胰腺炎患者腹腔高压和多脏器功能不全的作用.方法 根据病例入选和排除标准,4个医学中心共有120例重症急性胰腺炎患者入选.所有患者就诊时距离初发症状时间均在72 h之内,年龄18～65岁.随机分为研究组(n=59)和对照组(n=61).两组患者均实施重症急性胰腺炎早期综合治疗方案.对照组的容量治疗使用乳酸林格溶液;研究组除使用乳酸林格溶液外,同时静脉输注6%羟乙摹淀粉130/0.4氯化钠注射液.入组时及入组后监测患者液体平衡、腹内压、肺、肝、肾功能及APACHE Ⅱ评分.结果 入组后第4天和第5天,研究组平均腹内压低于对照组(P<0.05);调整基线效应和多中心效应后,平均腹内压相对基线的下降幅度自第2天开始明显大于对照组(P<0.05);两组腹内压高峰值出现时间的分布无差异(P>0.05),但研究组腹内压高峰出现时间有前移趋势.研究组液体正平衡总量低于对照组(P=0.041);液体负平衡出现时间早于对照组(P=0.036).两组各个时间点的APACHE Ⅱ评分的差异均无统计学意义(P>0.05),但调整基线效应和多中心效应后,自第4天开始,研究组相对基线值下降的幅度大于对照组(P<0.05).相关性分析显示,APACHE Ⅱ评分与腹内压水平呈正相关.研究组的氧合指数大于对照组(P<0.05).结论 在重症急性胰腺炎患者早期治疗中应关注容量治疗对腹内压的影响,使用羟乙基淀粉130/0.4氯化钠注射液有助于减轻液体扣押、降低腹内压和APACHE Ⅱ评分、保护脏器功能.     

基于控制壁面压力分布的分级单边膨胀喷管设计及试验验证

提出了基于控制壁面压力分布的分级 单边膨胀喷管(SERN)设计思想。在强几何限制条件下,设计了一个基准模型A,与采用分级膨胀思想设计的模型B进行对比。然后,对模型B喷管进行缩比进行了冷流试验,试验与数值模拟结果吻合良好,说明数值模拟结果可靠。模型A与模型B数值模拟的对比结果表明,模型B喷管在推力性能下降很少的前提下,冷热态俯仰力矩差较模型A下降了44.6%,有效减小了飞行器的配平难度,验证了该设计思想的正确性。      

Optimization of Connecting Rod Design Parameters for External Fixation System: A Biomechanical Study

The role of connecting rod in healing process of a fractured bone has always been of significant importance for surgeons. Adding a connecting rod to the fixator would be a secure option for increasing stability without increasing infection rate. The roles of 4 design parameters of the connecting rod (ie, connecting rod diameter, elevation, material, and configuration) were assessed by using finite element models to calculate axial stiffness and interfragmentary strain at the fracture gap. Taguchi method was used to achieve an optimal design set for maximizing stability with regard to connecting rod variables. Also, analysis of variance (ANOVA) approach was employed to determine contribution percentage of each design parameter on outputs. For optimizing connecting rod design parameters, an optimal set of variables consisting of 11 mm, 40 mm, 200 GPa, and Type 3 external fixator were determined by Taguchi for connecting rod diameter, elevation, modulus of elasticity, and configuration, respectively. However, as Type 3 external fixator stability is a little more than Type 2, it would be better if Type 3 external fixator in Taguchi suggestion be replaced by Type 2 external fixator to be as minimally invasive as possible. Furthermore, ANOVA results revealed that the connecting rod configuration is the most important parameter with 95% and 96% effectiveness on the interfragmentary strain and axial stiffness.     

PDE Constrained Optimization and Design of Frozen Mode Crystals

We explore the use of PDE constrained nonlinear optimization techniques to optimize and design electromagnetic crystals which exhibit frozen mode behavior. This is characterized by Van Hove singularities in the dispersion relation, e.g., stationary reflection points and degenerate band edge points. Hence, the optimization process modifies the dispersion relation by adjusting the geometries and material parameters. The resulting algorithm is found to be capable of recovering all known crystal configurations as well as many new configurations, some of which display dramatically improved properties over previously used configuration. We investigate both gyrotropic photonic crystals and degenerate band edge crystals as well as the more complex case of the oblique incidence. In this latter case, we extend the investigation to the three-dimensional case to identify the first three-dimensional crystal exhibiting frozen mode behavior.     

应用均匀设计和响应面分析优化谷物早餐的挤压工艺

以小麦、燕麦和玉米粉为主要原料，以脆性和保脆性为主要指标，通过均匀设计得到挤压工艺中对品质影响较大的3个因素及其取值范围。再通过响应面分析对谷物早餐的挤压工艺进行优化，得出最佳的挤压工艺为：螺杆螺旋速度为334r／min；Ⅰ区温度为40℃；Ⅱ区温度为150℃；Ⅲ区温度为123．50℃；水分质量分数22．60％；蛋白质质量分数7．3％；脂肪质量分数8％。     

Simulation of Two-Dimensional Scramjet Combustor Reacting Flow Field Using Reynolds Averaged Navier-Stokes WENO Solver

The non-equilibrium chemical reacting combustion flows of a proposed long slender scramjet system were numerically studied by solving the turbulent Reynolds averaged Navier-Stokes (RANS) equations. The Spalart-Allmaras one equation turbulence model is used which produces better results for near wall and boundary layer flow field problems. The lower-upper symmetric Gauss-Seidel implicit scheme, which enables results converge efficiently under steady state condition, is combined with the weighted essentially non-oscillatory (WENO) scheme to yield an accurate simulation tool for scramjet combustion flow field analysis. Using the WENO schemes high-order accuracy and its non-oscillatory solution at flow discontinuities, better resolution of the hypersonic flow problems involving complex shock-shock/shock-boundary layer interactions inside the flow path, can be achieved. Two types of scramjet combustor with cavity-based and strut-based fuel injector were considered as the testing models. The flow characteristics with and without combustion reactions of the two types of combustor models were studied with a transient hydrogen/oxygen combustion model. The detailed results of aerodynamic data are obtained and discussed, moreover, the combustion properties of varying the equivalent ratio of hydrogen, including the concentration of reacting species, hydrogen and oxygen, and the reacting products, water, are demonstrated to study the combustion process and performance of the combustor. The comparisons of flow field structures, pressure on wall and velocity profiles between the experimental data and the solutions of the present algorithms, showed qualitatively as well as the quantitatively in good agreement, and validated the adequacy of the present simulation tool for hypersonic scramjet reacting flow analysis.     

Computational Fluid Dynamics‐Based Design Optimization Method for Archimedes Screw Blood Pumps

An optimization method suitable for improving the performance of Archimedes screw axial rotary blood pumps is described in the present article. In order to achieve a more robust design and to save computational resources, this method combines the advantages of the established pump design theory with modern computer‐aided, computational fluid dynamics (CFD)‐based design optimization (CFD‐O) relying on evolutionary algorithms and computational fluid dynamics. The main purposes of this project are to: (i) integrate pump design theory within the already existing CFD‐based optimization; (ii) demonstrate that the resulting procedure is suitable for optimizing an Archimedes screw blood pump in terms of efficiency. Results obtained in this study demonstrate that the developed tool is able to meet both objectives. Finally, the resulting level of hemolysis can be numerically assessed for the optimal design, as hemolysis is an issue of overwhelming importance for blood pumps.     

星点设计效应面法优化盐酸文拉法辛油包水乳剂处方

摘要目的 采用星点设计效应面法优化盐酸文拉法辛油包水乳剂处方,以获得稳定的乳状液。方法分别考察了乳化剂、盐酸文拉法辛、聚乙二醇和氯化钠用量对乳剂黏度、离心破坏率和平均粒径等指标的影响。用线性方程和二次多项式描述各指标及总评“归一值”与4个因素之间的数学关系,根据总评“归一值”的最佳数学模型描绘效应面,选择最佳处方,并进行预测分析。结果4个因素和3个评价指标及总评“归一值”之间存在定量关系。优选的最佳处方：乳化剂P135为0.48 g,盐酸文拉法辛0.40 g,聚乙二醇0.26 g及氯化钠0.025 g。优化处方各指标的预测值和目标值接近。结论所建立的模型预测性良好,可用于优化盐酸文拉法辛油包水乳剂处方,并获得性质稳定的乳状液。     

正交旋转回归试验优化纤维素酶发酵培养基

利用旋转回归法研究里氏木霉WX-112发酵生产纤维素酶的两个重要因素：微晶纤维素粉（Avicel）和麸皮对滤纸酶活的影响，并拟合出回归方程。经回归分析表明，培养基中Avicel、麸皮的含量及其配比对滤纸酶活有显著影响。通过岭脊分析寻优得出：Avicel最佳浓度为1．34g／dL、麸皮最佳浓度为3．35g／dL，在此优化条件下滤纸酶活可迭6．51U／mL。用30L发酵罐进行放大试验，滤纸酶涪可达10．84U／mL，CMCase达到449．57U／mL。