Dynamic consistency of fuzzy conditional temporal problems

Conditional Temporal Problems (CTPs) can deal simultaneously with uncertainty and temporal constraints, allowing for the representation of temporal and conditional plans. CTPPs generalize CTPs by adding preferences to the temporal constraints and by allowing fuzzy thresholds for the occurrence of some events. Here we focus on dynamic consistency of CTPPs, the most useful notion of consistency in practice. We describe an algorithm which allows for testing if a CTPP is dynamically consistent and we study its complexity. Simple temporal problems with preferences and uncertainty (STPPUs) are another formalism to model temporal constraints where preference and uncertainty coexist. While uncertainty is CTPPs is modeled via conditions on the execution of variables, in STPPUs it is modelled by means of events whose occurrence time is not known. We consider the relation between CTPPs and STPPUs and we show that the former framework is at least as expressive as the second one. Such a result is obtained by providing a polynomial mapping from STPPUs to CTPPs.     

LC无源无线气体传感器的制备及对NH3气敏特性的研究

采用酸化后的碳纳米管与聚苯胺掺杂作为传感器的气敏材料.通过丝网印刷技术将无铅铝浆印刷在氧化铝陶瓷基板上形成电感线圈,并将制备好的气敏材料涂覆到电感线圈上,制备出LC谐振式无源气体传感器.制作成气体传感器后在NH3气氛中进行测试分析,实现了在密闭环境下的非接触测量.重点分析了在室温下NH3气体的浓度对传感器谐振频率f0的变化及响应恢复时间的影响,结果表明气体浓度在300×10-6时,传感器的灵敏度为4.499 MHz.     

Interactions of the surface heat and moisture transfer from the human body under varying climatic conditions and walking speeds

The surface heat and moisture transfer from the human body are normally characterized by the thermal insulation and moisture vapor resistance, which are important parameters in environmental engineering. In the past, due to the limitation of measurement technology, simultaneous measurement of these two parameters was not possible and hence there is a lack of clear understanding on the interaction of surface heat and moisture transfer. In this paper, through the experimental measurements on a newly developed sweating/non-sweating fabric manikin (named WALTER) under varying climatic conditions and "walking" speeds, we show that the surface thermal insulation is little affected by moisture transfer. The surface moisture vapor resistances measured under isothermal conditions tend to be greater than those measured under non-isothermal conditions, especially when the wind velocity is less than 2.0m/s. The Lewis Relation holds under non-isothermal conditions, but should be corrected under isothermal condition when the wind velocity is small.     

A microfabricated electrochemical actuator for large displacements

A large-displacement electrochemical actuator was designed, fabricated, and tested. The large displacement is obtained by using a corrugated membrane made by physical vapor deposition of Parylene sandwiched with an intermediate layer of sputtered platinum. The layered structure is approximately 8-μm thick, with 26 grooves approximately 120-μm deep, and with a radial period of 350 μm. The electrochemical cell consists of platinum electrodes with a 1 M H₂ SO₄ solution. Hydrogen and oxygen gas is generated to displace the membrane. Although the actuator can operate at a voltage as low as 1.23 V, the experimentally determined efficiency of converting electrical energy to mechanical work is only 0.37%. The governing equations for the conservation of mass, momentum (equilibrium), energy, and the entropy generation rate were formulated assuming that the gas bubbles either nucleate without growth or grow without nucleation. For the nucleation case, simulations were performed for constant pressure isothermal actuation, and the average experimental efficiency was bounded by simulations with gas bubble radii between 1×10^-6 m and 1×10^-6 m. The predicted ratio of the power dissipated to the electrical power supplied is 1.37 for isothermal actuation     

Electrophoresis of a finite rod along the axis of a long cylindrical microchannel filled with Carreau fluids

The boundary effect on the electrophoretic behavior of a particle in a non-Newtonian fluid is studied by considering the electrophoresis of a finite rod along the axis of a cylindrical microchannel filled with shear-thinning Carreau fluids, which include both Newtonian and power-law fluids as special cases. Under the conditions of low surface potential and weak applied electric field, the influences of the radius of the microchannel, the aspect ratio of the rod, the thickness of double layer, and the nature of the Carreau fluid on the mobility of the rod are investigated. We show that due to the shear-thinning effect, the mobility of the rod in the present case can be significantly larger than that in the corresponding Newtonian case; the former is more sensitive to the variation in the thickness of double layer than the latter, and the difference between the two increases with decreasing thickness of double layer. The shear-thinning effect is important under the following conditions: the double layer is thin, the boundary effect is important, and/or the aspect ratio is large. We show that increasing the aspect ratio can either raise or lessen its mobility, which is not found previously, and can play an important role in electrophoresis measurement.     

On-board phthalocyanine gas sensor microsystem dedicated to the monitoring of oxidizing gases level in passenger compartments

The monitoring of in-vehicle pollutant concentrations by means of an on-board molecular semiconductor gas sensor microsystem is described in this paper. The main objective is to measure in real time with a high level of accuracy the variations of oxidizing gases concentration in bus passenger compartments to inform travelers or commuters and to evaluate the assessment of bus drivers’ exposure. A self-contained gas sensor microsystem of which the sensitive element is constituted by a thin layer of copper phthalocyanine has been developed, validated at laboratory under controlled experimental conditions and then implemented in a bus of the urban network of Clermont-Ferrand, France. Preliminary in-car measurements realized with commercial analyzers show that nitrogen dioxide is the major oxidizing gas present on urban roads and so is considered as the target gas in this study. Tests realized under artificially polluted atmosphere show the high performances obtained with our microsystem, such as high resolution, low threshold, good reproducibility, satisfying concentration range and real time detection. The calibration curve has been determined at laboratory by experiments made under low NO₂ concentrations in the range of those measured in urban atmosphere. The relation between sensor microsystem response and gas concentration is established with accuracy. The validation of our microsystem is illustrated by measurements realized under real conditions, i.e., in an urban bus. It shows that NO₂ concentration variations are mainly correlated with the nature of roads and that rates of pollutant measured in traffic are always greater than those measured by the nearest stations of the air quality control network.     

某型涡扇发动机进口空气流量测量参数敏感性分析

基于某型涡扇发动机飞行台试飞,以某型涡扇发动机进口空气流量的测量为研究对象;首先建立了发动机进口空气流量计算模型以及相应的误差计算模型,其次采用辨识方法确定了测量参数的敏感系数,最后针对测量参数的无量纲敏感系数随飞行高度和发动机状态的变化进行了分析;分析结果表明:发动机进口空气对测量截面半径最为敏感,其次为主流区总压、主流区总温和主流区总静压差,对附面层位移厚度敏感性较差,且在发动机设计状态附面层对空气流量的影响为3%。     

Effect of inlet and outlet boundary conditions on swirling flows

Numerical simulations are conducted for both three-dimensional, turbulent flow in a multi-channel swirler and axisymmetric, isothermal, turbulent flow in combustion chambers using the standard κ−ε turbulence model. Calculations are first carried out for three-dimensional, isothermal and turbulent flow inside the swirler channels in order to derive the velocity profiles of both air and gas at the swirler outlets, which are used as inlet boundary conditions of the model combustor and can also be used in future studies for different combustors with the same type of swirler. In order to study the sensitivity of swirling flow inside the chamber to the inlet and outlet boundary conditions, different inlet velocity profiles and outlet boundary conditions are also employed. The results show that in the cases considered, the flow behaviour in the chamber is not very sensitive to the actual shape of the inlet velocity profiles provided the averages of the inlet axial, radial and azimuthal velocity components are separately preserved. Other conditions being equal, we find that the swirling flow performance in the combustor depends not only on the inlet swirl number, but also strongly on the relative magnitude of the radial velocity component at inlet and introduce a new dimensionless number N_r, analogous to the swirl number, to measure the relative importance of this quantity. Outlet boundary conditions have some influence near the outlet, but nearly no effect further upstream for the cases investigated.     

用热敏液晶粒子实现流体温度场的可视化

热敏液晶是图象测量技术研究中采用的新型敏感材料，针它密封装入圆球形微型胶囊中，要实现流体温度场的可视化定量计量。热敏液晶的ＲＧＢ值与温度之间的特性具有严重的非线性，而且因实验条件不同而异。本文介绍了它的色／温转换特性和摄影视角对该特性测量时的影响及其解决方法。     

轧钢加热炉燃烧工况在线测控系统

针对某大型钢厂轧钢加热炉系统在线实时性不强,采集数据不足,现场管理不便等问题,提出了构建加热炉燃烧工况在线测控系统。利用烟道气分析仪,在加热炉加热段增设多个燃烧气氛采集点,结合PLC和上位机组态软件,可以在线测量炉内不同区段残氧量与可燃物浓度,实现空气过剩系数的在线调整优化。同时,开发了节能量与氧化烧损两个模块,可用于实时估算可实现节能量与钢坯氧化烧损量。项目实施结果表明,炉燃烧工况在线测控系统可以实现加热炉内燃烧状况精确控制,有效降低燃气消耗。     

Hydrogen sensing characteristics of vertical type hydrogen sensors based on porous 3C-SiC with catalyst materials

The hydrogen-sensing characteristics of porous 3C-SiC (p-SiC) with different catalyst metals were investigated. The scanning electron microscopy results confirm that the 3C-SiC film has a porous structure with a pore size of 20–30 nm. Hydrogen sensing behavior of Pd/p-SiC was analyzed as a function of hydrogen concentration by current–voltage (I–V) and ?I-t methods under steady state and transient conditions. The Pd was used as a Schottky contact and detection material. The Pt and Au catalyst metals were deposited on Pd layer to increase the hydrogen sensing characteristics. The change in current was monitored in the range of 210–610 ppm hydrogen concentrations. The deposited Pt was more sensitive to hydrogen gas than the Pd and Au catalyst metals. It is evaluated that the hydrogen sensing properties of porous 3C-SiC Schottky-diode can be improved by Pt and Pd catalytic metals.     

Epitaxially grown graphene based gas sensors for ultra sensitive NO2 detection

Epitaxially grown single layer and multi layer graphene on SiC devices were fabricated and compared for response towards NO₂. Due to electron donation from SiC, single layer graphene is n-type with a very low carrier concentration. The choice of substrate is demonstrated to enable tailoring of the electronic properties of graphene, with a SiC substrate realising simple resistive devices tuned for extremely sensitive NO₂ detection. The gas exposed uppermost layer of the multi layer device is screened from the SiC by the intermediate layers leading to a p-type nature with a higher concentration of charge carriers and therefore, a lower gas response. The single layer graphene device is thought to undergo an n-p transition upon exposure to increasing concentrations of NO₂ indicated by a change in response direction. This transition is likely to be due to the transfer of electrons to NO₂ making holes the majority carriers.     

Simulation of the aquaplane problem

Finite-element analysis (FEA) has been widely integrated into the tire design process as a useful numerical tool for the investigation of various behavioural conditions of tires during their service life. Recently, much interest has been directed towards the contact of a tire with a water layer together with steering and braking capability (especially for the landing of airplanes). In this paper, we present several possibilities for the modeling of aquaplane problems with the ADINA system. The solution results, which relate to the character of fluid-flow pressure distribution and lift forces obtained by the steady-state analysis, yield important information for tire design. The water under the tire is considered to be an isothermal incompressible fluid and the tire structure is considered a deformable body.     

太赫兹波段超材料在核酸恒温指数扩增检测上的应用

超材料对电磁场具有介电环境敏感和局域电场增强等奇特的电磁特性,近年来广泛用于无标记生物检测。文中设计并制作了一种金属开口谐振环阵列结构的超材料,在太赫兹波段下分别检测核酸恒温指数扩增前后反应体系,在氮气干燥环境下,扩增反应前后的频率偏移量分别为Δf1=（54±3）GHz、Δf2=（60±5）GHz。实验结果显示金属开口谐振环阵列结构的超材料可以作为一种生物传感器快速无标记检测核酸扩增前后的变化。     

基于PVDF膜的QCM对DMMP的气敏特性研究

神经性毒剂是化学战剂的重要分支.为了检测神经性毒剂模拟剂甲基膦酸二甲酯(DMMP),使用毛细管在压电石英晶体(QCM)的电极上滴涂上不同质量的聚偏氟乙烯(PVDF)溶液,干燥后作为敏感膜.室温下测试QCM对不同浓度的DMMP的响应情况,发现QCM的频率变化与气体浓度有着良好的线性关系.该实验结果表明,PVDF可以作为检测DMMP的很好的敏感材料.     

金属氧化物气敏元件稳定性的研究进展

金属氧化物气敏元件性能的不稳定制约了元件的实用化进程,气敏元件稳定性的研究成为气体传感器技术中的一项重要内容。概述了金属氧化物气敏元件稳定性的研究进展,介绍了敏感材料、敏感材料的制备工艺、载体材料、加热/测量电极等因素对稳定性的影响。分析了各种影响因素的作用机理,并对其研究前景进行了展望。     

Determination of adhesive forces and sticking temperature of coated glasses for the hot-embossing-process

In contrast to previous studies a new coating strategy was developed to decouple the viscosity in the glass volume from the sticking behaviour at the glass surface. Not the mould, but the glassy substrate was coated with a thin, adhesive and ductile layer. For that purpose, soda-lime silica and borosilicate glasses were coated with gold, chromium, carbon, silica or titanium oxide. The isothermal hot embossing was carried out under air or, however, under argon atmosphere with a pressure of 500 Pa. Under vacuum inert gas atmosphere, all examined coatings shift the sticking temperatures by around 80 K to temperatures near the Littleton-temperature of the glass, which is even higher than the temperature process range of micro structuring. The adhesive forces are <10% in comparison to those observed at uncoated glass substrates. Under air, the increase in the sticking temperature is not as pronounced. The coatings on the glass enable to apply hot embossing at higher temperatures and hence at smaller viscosities. Hence high shear rates and a reduction of embossing forces are enabled.     

镉、锡复合氧化物及掺银薄膜的气敏光透射特性

ＣｄＯ－ＳｎＯ２复合氧化物是对乙醇气体选择性较好的敏感材料［１］，但灵敏度比纯ＳｎＯ２低。对镉、锡复合氧化物掺微量银后，灵敏度明显提高。掺银薄膜的气敏光透射特性好，可检测乙醇饱和气体的浓度高且重复性好。     

多气参测量的压力型基准大气数据系统研制

针对某飞行器嵌入式大气数据传感(FADS)系统的飞行试验校准问题,研制了一套压力型姿态角测量的多气参基准大气数据系统。设计了可实现高线性度、解耦的压力型姿态角测量空速管,并配套研制了大气数据计算机。解决了有限空间内多气路之间密封、同时精确取气和压力测量、飞行器机体干扰下的风洞试验标定、多参数拟合修正的气参解算等难题,获得了机体干扰下的空速管测量修正解算公式,实现了基准气参的高精度测量。在完成基准空速管的风洞试验标定和联调试验后,实现了对全系统正常工况下的飞行参数测量精度及系统稳定性考核,最终成功应用于飞行试验中。     

Direct Simulation of Moderately Rarefied Gas Flows in Two-Dimensional Model Porous Media

The applicability of a quasi-hydrodynamic system of equations to the simulation of moderately rarefied gas isothermal flows in two-dimensional domains with a complex geometry typical for pore spaces of rock samples is numerically studied. In order to take into account gas slippage effect on the solid boundaries the classical Maxwell slip boundary conditions are used, for which an approximation is proposed and the implementation algorithm is described. The simulation results are presented for several samples under different average pressure values. A qualitatively correct dependence of the Klinkenberg slip factor on the ratio of the absolute permeability coefficient to the sample porosity is revealed.