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11.
针对传统的容积型流阻差式无阀压电泵具有吸入周期和排出周期,存在着流动脉动大、流量小的问题,提出一种新型的鱼鳍摆动式无阀压电泵。模仿在鱼类中巡游速度最快的金枪鱼的鱼体结构,设计了压电双晶片结构的压电振子,并将其尾鳍设计成柔性叶片状。分析了压电双晶片结构悬臂梁的受力变形、模态振型在机电转换效率方面的关系。研制了泵的样机并测量了激励电压在100 V时泵的流量。实验结果表明:振子工作在1阶振型时,泵水效应不明显;振子工作在2阶振型时,谐振频率为740 Hz,泵的流量为266 mL/min;振子工作在3阶振型时,谐振频率为1 280 Hz,泵的流量为105 mL/min。 相似文献
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Micromixers to produce cosmetic emulsions 总被引:1,自引:0,他引:1
Tromeur M Mahé C Schwesinger N Tranchant JF 《International journal of cosmetic science》2003,25(1-2):1-4
In the cosmetics industry, emulsions play a key-role in active solubilization and texture/efficacy optimization. However, depending on their physico-chemical properties, the active ingredients are often more stable in a single phase: for example, Vitamin A is more stable in an oily phase than in a water phase. We have developed a special mixing device which produces an emulsion in the body of the pump, immediately before application on the skin. The mixing unit consists of two silicon chips. Each chip has several Y-shaped microchannels and intersections etched on its upper surface. When the two etched surfaces are bonded together, they produce series of interconnecting micromixing elements which permit the repeat mixing of the two phases, thus producing an extremely homogenous emulsion. These micromixers require carefully designed formulae in which the physico-chemical properties of each raw material are essential to obtain a spontaneous emulsion. This device has been incorporated into a spray pack and optimized to deliver the spontaneous emulsion when finger pressure is applied. 相似文献
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While strategies employing early or late direct-injection of fuel can improve emissions, they also can lead to impingement of liquid-phase fuel on the piston and/or cylinder wall due to low in-cylinder temperatures and densities during the injection event. Previous work has shown that liquid-phase fuel films formed in this way can lead to pronounced degradations in efficiency and emissions. To avoid these problems, a quantitative understanding of fuel-property effects on the liquid penetration length is needed, and this understanding must include conditions where in-cylinder thermodynamic conditions and the injection rate vary with time. This work reports liquid penetration lengths measured in an optical engine under such time-varying conditions. Diagnostics included laser light scattering for measurement of the liquid length and conventional pressure-data acquisition for heat-release analysis. Unsteady liquid penetration was characterized for different injection timings, injection pressures, intake-manifold pressures, and fuel volatilities to gain an understanding of the relative importance of these factors. Fuel volatility was studied by using two fuels, 2,2,4,4,6,8,8-heptamethylnonane (HMN) and 2,2,4-trimethylpentane (TMP), which have very different volatility characteristics. Measured liquid lengths changed as in-cylinder conditions changed, with increasing temperature and density during the compression stroke causing a decrease in liquid length, and decreasing temperature and density during the expansion stroke causing an increase in liquid length. Intake-manifold pressure and fuel volatility were found to be primary factors governing liquid length. Heat loss from the charge gas to the engine and local charge cooling due to fuel vaporization were found to have a secondary influence on liquid length. Injection pressure was found to have little effect. 相似文献
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以固定协调控制下绿信比确定方法及感应控制原理为基础,设计了基于逻辑规则的感应式协调控制下绿信比优化流程,提出了感应协调控制下绿灯时间实时优化方法,确定了最大弹性绿灯时间计算方法。算例表明,该方法具有较好的实用性。 相似文献
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