多极板电流变阀应用于避震器之研究

以流动模式(flow mode)多极板之电流变阀(electrorheological valve) 进行避震器阻尼力特性的研究.由于电极板的大小直接影响到流体流动的剪力及避震器的阻尼力,因此使用多极板型式来探讨避震器的特性.设计有1～5个流道之并联及1～3个流道之串联多极板电流变阀的电流变避震器,并使用自制的电流变液进行实验.由研究结果显示,流动式并联极板之电流变避震器,一个流道之阻尼力最大,流道极板增加则阻尼力反而下降,而流动式串联多极板之电流变避震器之阻尼力则随极板数递增,故需要高阻尼力之避震器较适合使用串联多极板型式.     

A Dynamic Model and Parameter Identification of High Viscosity Magnetorheological Fluid-Based Energy Absorber with Radial Flow Mode

The excellent suspension stability of the high-viscosity linear polysiloxane magnetorheological fluid (HVLP MRF) makes it a great controlled medium for magnetorheological energy absorbers (MREAs). In our previous work, the Herschel–Bulkley flow model (HB model) was used to describe the shear-thinning rheological behavior and establish the dynamic model of an HVLP MRF-based MREA with radial flow mode. However, as the established model was implicit, the MREA response time increased and the buffer effect was degraded. To improve the time response characteristics, an explicit dynamic model based on the HB model incorporating minor losses (called the E-HBM model) is proposed in this study. The model parameters were identified based on the HBM model. To verify the E-HBM model, five evaluation parameters for the energy absorption performance of the MREA, that is, peak force, mean force, crush force efficiency, specific energy absorption, and stroke efficiency, were introduced to compare the theoretical results with the experimental results obtained using a high-speed drop tower facility with a mass of 600 kg. Then, the relative error of the crush force efficiency, specific energy absorption, and stroke efficiency was quantitatively and comprehensively analyzed considering the E-HBM model and experimental results. The results indicate that the proposed E-HBM model agrees with the impact behavior of the radial flow mode MREA.     

The Research on the Principles of Component of Magnetorheological Fluid Selecting and Its Mechanism

Because of its extensive applying prospect, magnetorheological fluid and its device have been concerned by many domain,but the lack of good magnetorheological fluid that can be used in real engineering is hindering the developing of this technology. Firstly, from the direction of the mechanism of rheologic and its performance objective, the principles of components of magnetorheological fluid selecting and their affects on fluid’s performance are studied. Secondly, the technology of disperse is researched. At last, the performance of a kind of magnetorheological fluid that made by the above principles is introduced.     

磁流变体流变学特性研究

对所研制的矿物油介质和硅油介质磁流变体样品的零场粘度、磁流变性能、示功及速度特性进行了系统的测试和分析,并对其影响因素进行了详细的讨论.研制的磁流变体零场粘度小于0.5 Pa s(γ=81 s-1)且具有良好的粘温特性; 磁流变体的剪切应力接近和超过70 kPa(B=6000 Gs); 在智能减振器的应用试验中获得理想的示功特性曲线.     

基于激波管装置的乙烯氧化实验研究与动力学机理分析

在乙烯/氧气化学计量比为1,温度1092-1743 K,压力1.3-3.0 atm (1 atm = 101325 Pa)范围内,利用激波管测量了在摩尔分数为96%和75%两种不同氩气稀释度工况下的乙烯/氧气/氩气反应体系的着火延迟时间。实验结果表明,乙烯着火延迟时间在低稀释度下比高稀释度下短,着火延迟时间的对数与温度的倒数成良好线性关系,随着温度增加着火延迟时间缩短。此外,低稀释度下,能观察到爆轰(或者爆燃转爆轰)现象,而在高稀释度下,未发生爆轰现象。将四种不同机理模拟结果与实验结果比较,发现LLNL机理与实验结果吻合得较好。反应路径分析研究表明,稀释度对乙烯氧化反应路径无影响,而温度影响较大,温度增加,乙烯消耗路径由四条减少为三条,反应C₂H₄ + H (+ M) = C₂H₅ (+ M)由正向消耗乙烯变为逆向生成乙烯。     

A Highly Efficient UV‐C Absorber Based on Theoretical and Experimental Studies

Based on two published UV absorbing molecules 2‐(5′‐tert‐butyl‐2′‐hydroxyl)benzotriazole (Tinuvin‐PS ) and hydroxybenzophenone (HBP ), both having characteristic absorption capability, a refined UV absorber, 2‐(3′‐benzoyl‐2′‐hydroxy‐5′‐tert‐butylphenyl)benzotriazole, has been synthesized. This new UV absorber exhibits a wider absorption range and better thermal stability compared to either Tinuvin‐PS and HBP and a higher absorption efficiency in the UV ‐C range. Theoretical studies reveal that the UV ‐C absorption arises from the electron density transfer from the Tinuvin‐PS moiety to the HBP moiety and the enhanced absorption efficiency is ascribed to the presence of the carbonyl's π system.     

基于多链模型的磁流变弹性体剪切模量的数值分析

Based on the magnetic interaction energy, using derivative of the magnetic energy density, a model is proposed to compute the magnetic-induced shear modulus of magnetorheological elastomers. Taking into account the influences of particles in the same chain and the particles in all adjacent chains, the traditional magnetic dipole model of the magnetorheological elastomers is modified. The influence of the ratio of the distance etween adjacent chains to the distance between adjacent particles in a chain on the magnetic induced shear odulus is quantitatively studied. When the ratio is large, the multi-chain model is compatible with the single chain model, but when the ratio is small, the difference of the two models is significant and can not be neglected. Making certain the size of the columns and the distance between adjacent columns, after constructing the computational model of BCT structures, the mechanical property of the magnetorheological elastomers composed of columnar structures is analyzed. Results show that, conventional point dipole model has overrated the magnetic-induced shear modulus of the magnetorheological elastomers. From the point of increasing the magnetic-induced shear modulus, when the particle volume fraction is small, the chain-like structure exhibits better result than the columnar structure, but when the particle volume fraction is large,the columnar structure will be better.     

Shock Tube Measurement of Ethylene Ignition Delay Time and Molecular Collision Theory Analysis

In this study, 75% and 96% argon diluent conditions were selected to determine the ignition delay time of stoichiometric mixture of C₂H₄/O₂/Ar within a range of pressures (1.3-3.0 atm) and temperatures (1092-1743 K). Results showed a logarithmic linear relationship of the ignition delay time with the reciprocal of temperatures. Under both two diluent conditions, ignition delay time decreased with increased temperature. By multiple linear regression analysis, the ignition delay correlation was deduced. According to this correlation, the calculated ignition delay time in 96% diluent was found to be nearly five times that in 75% diluent. To explain this discrepancy, the hard-sphere collision theory was adopted, and the collision numbers of ethylene to oxygen were calculated. The total collision numbers of ethylene to oxygen were 5.99×10³⁰ s^-1cm^-3 in 75% diluent and 1.53×10²⁹ s^-1cm^-3 in 96% diluent (about 40 times that in 75% diluent). According to the discrepancy between ignition delay time and collision numbers, viz. 5 times corresponds to 40 times, the steric factor can be estimated.     

高活性聚苯胺电流变液的制备与性能研究

高活性聚苯胺电流变液的制备与性能研究官建国，谢洪泉，过俊石（华中理工大学化学系，武汉，４３００７４）关键词电流变液，聚苯胺，反掺杂，电荷迁移极化电流变液（ＥＲＦ）是重要的人工智能材料和高效机电一体化的功能液体［１］．目前，研究ＥＲＦ技术的关键是提高Ｅ...     

可穿戴式微流控芯片在体液检测和药物递送中的研究进展

可穿戴式微流控芯片在医疗、体育、军事等领域具有广泛的应用潜力,利用可穿戴式微流控芯片对人体体液进行实时监测,可以通过芯片与皮肤的接触,方便地对汗液、泪液、唾液等体液进行采集,并分析和传输数据,可以实时获取汗液pH值以及血糖、乳酸盐、钠/钾离子、钙离子、重金属等的含量的信息,这些体液信息对于个体生命体征的实时监测和疾病诊断有着重要的指示性作用.本文介绍了近年来可穿戴式微流控芯片在体液检测和药物递送方面的最新研究进展,以及利用可穿戴式微流控芯片进行生命体征监测的应用案例.本文还简要介绍了利用可穿戴式微流控芯片进行精准药物递送的最新研究动向和应用进展,并对可穿戴式微流控芯片发展过程可能遇到的问题进行了分析,对未来融合发展的前景进行了展望.     

Investigation on the Adaptability of the Polymer Microspheres for Fluid Flow Diversion in Porous Media

Large amounts of water producing from producers have been a great concern for petroleum engineers. In an attempt to inhibit water production and promote oil productivity, various water control agents and techniques have been devised for enhanced oil recovery purpose for decades with some good successes reported commercially. Mainly field-targeted specifically, however, these chemicals are limited in expansive reservoir applications for failing to tolerate harsh formation conditions of high temperature (HT) and high salinity (HS). Besides, their low injectivity is also another proper impediment. In this presentation, we synthesized a new agent of polymer microspheres using inverse emulsion polymerization technique to divert fluid patterns in deep porous media for reservoirs encountered recovery enhancement problems. These microspheres are made to tolerate HT and HS conditions, and can be pumped into deep pore space with relative ease. With the help of nuclear magnetic resonance (NMR) and nuclear pore membrane filtration techniques, a series of experimental procedures were conducted to test the adaptability of newly produced polymer microspheres to targeted pore structure in enhancing the sweeping efficiency of injection fluids. Both laboratory core tests and NMR data show good characteristics of polymer microspheres in modifying injection profile, demonstrating a good capability to divert fluid flow patterns in deep porous media and enhance oil productivity.     

基于棒状介孔SiO_2剪切增稠流体的流变行为

以三嵌段共聚物聚氧乙烯-聚氧丙烯-聚氧乙烯(PEO-PPO-PEO,P123)为模板剂,采用溶胶-凝胶法合成了介孔SiO_2-P123复合物,经煅烧除去P123得到不同长径比的棒状介孔SiO_2粒子,将其分散于聚乙二醇(PEG)中制成剪切增稠流体(STF),利用旋转流变仪对STF的流变性能进行了表征。结果表明:在稳态条件下,STF的剪切增稠效应随介孔SiO_2质量分数的增加而增强,随介孔SiO_2粒子长径比的增加而减弱;在动态条件下,STF的剪切增稠效应随介孔SiO_2质量分数的增加而减弱,随介孔SiO_2粒子长径比的增加而增强。     

超临界流体萃取在环境分析中的应用

按基体的不同形态综述了１９９３年以来超临界流体萃取在痕量环境污染物分析中的最新进展情况,５５篇。常见萃取分析的有机污染物主要包括多环芳烃、多氯联苯、二咕恶咕英、石油烃类、酚类化合物、农药和除草剂残留、金属离子和表面活性剂等。     

Effect of Cooling Fluid Flow Rate on the Estimation of Conversion by Calorimetry in a Lab-Scale Reactor

Significant information about polymerization reactions carried out in lab-scale reactors is lost because sampling is not always possible due to the high viscosity, heterogeneity of the reaction medium or pressurization of the reactor. Thus, monitoring these reactions through calorimetry technique could be very valuable. Nevertheless, standard lab-scale reactors can present a relatively high residence time of the cooling fluid in the jacket and significant heat loss of the jacket to the surroundings. In the present work, the effect of the cooling fluid flow rate on the estimation of conversion through isothermal and isoperibolic calorimetry during a batch emulsion polymerization was investigated. Results show that the estimation of conversion through isothermal and isoperibolic calorimetry was not significantly affected by the cooling fluid flow rate using heat flow calorimetry. Nevertheless, when employing the energy balance of the jacket and the estimation of the global heat exchange coefficient between the jacket and the surroundings to estimate conversion (heat balance calorimetry) better results were obtained for lower cooling fluid flow rates.     

Effect of CO2 Flow Rate on the Extraction of Astaxanthin and Fatty Acids from Haematococcus pluvialis Using Supercritical Fluid Technology

Haematococcus pluvialis is the largest producer of natural astaxanthin in the world. Astaxanthin is a bioactive compound used in food, feed, nutraceutics, and cosmetics. In this study, astaxanthin extraction from H. pluvialis by supercritical fluid extraction was evaluated. The effects of temperature (40 and 50 °C), pressure (40 and 50 MPa), and CO₂ flow rate (2 and 4 L/min) were investigated. The results showed that the highest astaxanthin recovery was obtained at 50 °C/50 MPa and the CO₂ flow rates evaluated had no significant effect. It was possible to achieve astaxanthin recoveries of 95% after 175 min for a CO₂ flow rate of 2 L/min, and 95 min for CO₂ flow rate of 4 L/min. The ω-6/ω-3 ratios obtained were similar in all conditions, reaching 0.87, demonstrating that the extracts from H. pluvialis by SFE are rich in unsaturated fatty acids (UFA) which increases their positive effects when used as a functional ingredient in food.     

磁性流体的制备、应用及其稳定性的解析

本文概括地介绍了磁性流体的特性和制备方法, 重点论述了磁性流体的应用,对磁性流体的稳定性进行了解析。     

西藏红景天超临界流体萃取及萃取物的GC-MS分析

探讨了西藏红景天的超临界流体萃取工艺,应用GC-MS方法对萃取物成分进行了分析.结果表明,最佳提取工艺条件为:夹带剂乙醇的体积分数为85%,萃取温度为55℃,萃取压力为30 MPa,萃取时间为2 h.此条件下红景天萃取物得率为5.65%.GC-MS分析鉴定出32种组分,主要为醇类、酯类、烷烃、烯烃等化合物,并应用峰面积归一化法测定了其相对含量.     

Simulation of Flow Field for Pulsatile Blood Flow in a Femoral Artery Based on Cosserat Continua

This investigation describes unsteady, pulsatile, laminar, and locally fully developed blood flow velocity and rotation fields during cardiac cycle in the femoral artery using Cosserat continuum mechanics approach. After solving the continuity, linear momentum, and angular momentum equations for flow of blood through artery, the time and position dependent velocity and rotation fields have been calculated. It is shown that the maximum values of velocity occur at the inlet core, while the maximum values of rotation occur on the arterial boundary. It is also demonstrated that the flow of blood in artery is laminar and a good agreement with existing data is established. A time dependent Gaussian equation for non-Newtonian blood viscosity coefficient γ_v has also been found.     

Analysis and Verification on the Chain-like Model with Normal Distribution of Magnetorheological Elastomer

Magnetorheological elastomer （MRE） is a new kind of smart materials, the rheological properties can be controlled rapidly by the external magnetic field. It is mainly composed of rubber and micron-sized ferromagnetic particles, which forms a chain-like structure. Therefore its mechanical, electric, and magnetic properties can be changed by the applied magnetic field, which is called as the magneto-induced effect. But this effect is not remarkable enough currently for the engineering application. So it is important for material preparation to optimize parameters to enhance the magneto-induced effect. In this work, based on chain-like model, some factors influencing the magneto-induced effect of MRE were analyzed theoretically by using dipole method with the normal distribution of chain＇s angle introduced. The factors included the oblique angle of particles chains, magnetic field intensity, and shear strain, etc. Some experiments were also carried out.