Nanocrystalline graphite-like pyrolytic carbon film electrode for electrochemical sensing of hydrazine

Pyrolytic carbon film (PCF) electrode fabricated by a non-catalytic chemical vapor deposition (CVD) process was used as an electrochemical sensor for the detection of hydrazine. The electrode response was found to be electrocatalytic producing a reduction in the overpotential compared to other unmodified carbon-based electrodes such as glassy carbon (GC), basal-plane pyrolytic graphite (BPPG), and edge-plane pyrolytic graphite (EPPG) electrodes. The overall number of electrons involved in the electro-oxidation of hydrazine, the number of electrons involved in the rate-determining step, and diffusion coefficient of hydrazine at PCF electrode were estimated using cyclic voltammetry and chronoamperometry. The performance of PCF electrode was comparable to and in some cases even better than many chemically modified electrodes in terms of detection limit, linear dynamic range, and sensitivity. Moreover, the sensor exhibited fast response time (within 2 s), high response stability, and reproducibility. All the results indicated this sensor is suitable for hydrazine analysis.     

A novel method for the fabrication of high-aspect ratio C-MEMS structures

A novel fabrication process was developed to create high aspect ratio (>10:1) carbon posts, all-carbon suspended bridges and wires, self-organized bunches of carbon posts, and carbon plates supported by carbon beams. The structures are all made from a two-step pyrolysis process with SU-8 photoresist as the starting material. In this paper we describe the fabrication of these various new C-MEMS structures and detail an important application of the high aspect ratio carbon posts arrays. The carbon post arrays can be reversible charged/discharged with Li ions, an application that may greatly impact the application of C-MEMS in three-dimensional microbatteries. Complex suspended C-MEMS structures, such as wires, plates, ribbons, and self-organized bunches of posts, were built. Methods to accurately and repeatedly fabricate all the above 3-D C-MEMS structures are given.     

Multi-layer integration framework for low carbon design based on design features

Global warming has currently become the most discussed environmental issue. The major portion of the carbon emission for a product is determined at the design stage of its life cycle. Given that products are made of parts, one of the major difficulties is that existing carbon emission assessment methods are machining process-oriented and lack association with design information, which makes it difficult to support low-carbon design. To address this problem, this paper develops a multi-layer integration framework for part low-carbon design based on the association mechanism among five layers, i.e., design feature, machining process, machining feature, operation feature, and carbon emission feature. The carbon emission assessment model of the part could be obtained by the method of top-down expansion and bottom-up assessment in terms of the design features through the developed framework. To obtain a low carbon design scheme, an improved differential evolution algorithm (IDE) with the multi-layer encoding method is proposed based on the hierarchical relationship of the framework, which aims to minimize the potential carbon emissions of parts and makespan of its machining processes. The proposed methodology is verified by the low carbon design of a flange plate.     

Modular membrane valves for universal integration within thermoplastic devices

While much research has been conducted on elastomeric valves within PDMS microfluidic devices, we rarely see scalable manufacturing processes for integrating such valves into rigid thermoplastic devices. Most thermoplastic materials do not share intrinsic bonding compatibility to flexible elastomer membranes, making it difficult to ensure leak-proof operation of such valves within thermoplastic devices. In order to overcome bonding compatibility issues, we propose decoupling the valve architecture from the fluidic routing device layers. This can be achieved by prefabricating modular valves via molding processes and subsequently inserting them into thermoplastic layers containing valve seats. Thermoplastic layers containing modular valves are then thermally bonded to thermoplastic layers containing the fluidic routing channels, resulting in leak-proof valve integration. At valve actuation pressures of approximately 60 kPa, the modular membrane valves seal fluidic channels operating at a flow rate of 100 µl min^?1. Modular valves that were incorporated into a concentration gradient generator demonstrated dynamically configurable fluid routing at a response frequency of 5 Hz. The integration of modular membrane valves is an effective solution to streamline and cost-down the manufacturing of hybrid elastomer–thermoplastic devices. As this solution does not rely on bonding compatibility between the elastomeric membranes and the thermoplastic device, it can be applied universally to solve integration issues for low-cost thermoplastic device fabrication.     

Fabrication of X-rays mask with carbon membrane for diffraction gratings

We have produced diffraction gratings for obtaining high resolution X-ray phase imaging, such as X-ray Talbot interferometer. These diffraction gratings were required to have a fine, high accuracy, high aspect ratio structure. Therefore, we decided to use the X-rays lithography technique that used synchrotron radiation of the directivity for a manufacture process. The accuracy of the completed structure depends largely on the accuracy of the X-ray mask. In our group, a resin material is conventionally used for the membrane of large X-ray masks. However, X-ray masks comprising a resin membrane have the disadvantage that, after several cycles of X-ray exposure, they crease and sag due to X-ray-derived heat. As a substitute for the conventional resin membrane, we experimentally fabricated a new X-ray mask using a carbon wafer membrane. The newly fabricated X-ray mask was subjected to X-ray exposure experiment. We succeeded in making the structure body which was almost shape. And the experimental results verified that the new mask did not deteriorate even when used repeatedly, demonstrating that it was highly durable.     

Amperometric glucose biosensor based on integration of glucose oxidase with platinum nanoparticles/ordered mesoporous carbon nanocomposite

This article reports a new amperometric glucose biosensor based on ordered mesoporous carbon (OMC) supported platinum nanoparticles (Pt/OMC) modified electrode. The Pt/OMC nanocomposite modified electrode exhibited excellent electrocatalytic activities towards the reduction and oxidation of H₂O₂ as well. This feature allowed us to use it as bioplatform on which glucose oxidase (GOD) was immobilized by entrapment in electropolymerized pyrrole film for the construction of the glucose biosensor. The biosensor showed good analytical performances in terms of low detection (0.05 mM), high sensitivity (0.38 μA/mM) and wide linear range (0.05-3.70 mM). In addition, the effects of pH value, applied potential, electroactive interference and the stability of the biosensor were discussed. The applicability to blood analysis was also evaluated.     

悬挂运动控制系统中的循迹算法研究

为解决悬挂运动控制系统中的黑色间断曲线循迹问题,根据颜色传感器的安装位置和数量,并考虑到硬件电路功能和算法的复杂程度,对循迹算法进行了研究,选定了两种算法进行试验,即一个传感器画圆扫描法和四个传感器圆周均布法,实现了对黑色间断曲线的循迹。     

静电悬浮转子微陀螺悬浮控制系统的研究

针对一种新颖的基于MEMS技术的静电悬浮转子微陀螺,提出了悬浮控制系统的原理和设计,并着重对z轴悬浮控制系统的设计进行了分析,建立了Z轴方向悬浮控制系统的数学模型,通过分析扰动力对转子位移的影响,得出PID(比例-积分-微分控制)参数决定动态刚度,通过仿真结果可以看出,采用反馈线性化可补偿系统的负刚度特性,结合变预载控制实现转子的快速准确定位,为后续的旋转和加矩控制提供良好的条件.     

非平衡分子动力学在炭膜气体分离CH4/CO2中的模拟研究

通过建立单孔狭缝模型,采用非平衡分子动力学方法研究CH_4/CO_2二元气体混合物通过管状炭膜的传递和分离特性,考察了系统温度、气体组成和膜孔径对通量的影响。模拟过程中将膜低势,区压力取为更符合实际情况的非零值(大于零)。研究结果表明,在温度为20℃～160℃范围内,随温度升高,CH_4的通量增加,CO_2的通量则先降低后升高(80℃出现最低值);随混合气中CH_4组成的增加,CO_2通量下降、CH_4通量升高;随膜孔径增大,CH_4通量先增后减(9.77 (?)时出现最大值)、CO_2通量则呈下降趋势。以上模拟结果与实验数据相比较,吻合良好。在此基础上,本文还考察了跨膜压差对过程的影响,发现CH_4和CO_2的通量均随跨膜压差的增大而增大,膜的分离性能则随之降低。本研究结果充分表明,所建模型能够正确地描述CH_4/CO_2气体混合物的炭膜分离过程。     

No more bonding,no more clamping,magnetically assisted membrane integration in microfluidic devices

The integration of porous membranes with microfluidic devices allows a simple but high-throughput mass transport control for numerous microfluidic applications, such as single-cell separation, sample analysis, and purification. In this study, we demonstrate a novel integration process of porous membranes into microfluidic devices by applying a magnetic field and hydrodynamically stabilizing them. This new approach simplifies the integration process by removing physicochemical bonding between membranes and microfluidic devices, but overcomes many practical issues observed in current methods, such as device leakage, membrane replacement, and membrane material selection. More importantly, our approach allows us to install membranes with diverse physicochemical features and spatial configurations into a single microfluidic device. This additional ability can significantly improve its performance and capability in applications. Finally, we successfully demonstrate the utilization of our membrane device for simple particle separation.     

Electrothermally Actuated RF MEMS Switches Suspended on a Low-Resistivity Substrate

This paper presents an electrothermally actuated lateral resistive-contact switch for application to low-gigahertz-band communication systems. It was manufactured on a standard low-resistivity substrate, and its RF performance was improved by suspending the structures 25 mum from the substrate, which is a strategy for future integration with active devices in the system-on-chip concept. Measured insertion losses are -0.26 dB at 1 GHz and -0.65 dB at 6 GHz, return losses are -29 dB at 1 GHz and -25 dB at 6 GHz, and isolations are -52 dB at 1 GHz and -26 dB at 6 GHz. The device is driven by a metal electrothermal actuator, which achieves large displacements and contact forces at much lower temperatures than traditional polysilicon electrothermal actuators. The RF power handling characteristics are also addressed and measured.     

结构不平衡交跨线路悬垂串张力特性仿真研究

线路结构不平衡影响着悬垂串的张力特性,以某220kV耐直耐交叉跨越线路实际工程为背景,通过改变交叉跨越耐张段线路中的邻档档距和高差,研究大风工况下交叉跨越线路结构不对称特性对其悬垂串最大动张力的影响.建立了交叉跨越线路有限元模型,利用线性滤波法模拟大风工况下的脉动风速时程曲线,根据大风工况的模拟风速对不同交叉跨越线...     

A geometric note on integration

We propose a decomposition principle for the Riemann–Stieltjes integration and study some of its implications which lead to three distinct forms for the Riemann integral for monotonically varying differentiable functions.     

基于XML的信息集成研究

基于可扩展标记语言(extensible markup language,XML)的Web服务作为一种新型的信息集成架构已经受到来自数据库领域和软件工程领域的广泛关注.服务的整个构建、描述、发布、发现、数据传输过程都是以XML为基础的.在分析了XML的特性的基础上,提出将服务组合、调用的接口处理问题转换成XML数据的处理问题,将服务传送的异构数据、参数的处理转换成XML消息的处理.在此基础上,提出了基于XML的异构信息集成方案.该方案将异构数据库数据以及接口处理信息转换成XML文档,按照通用的XML文档的格式来访问异构系统服务,集成系统服务,并可以通过XML文档的加密/解密来保证系统内部数据的安全性.最后还分析了基于XML的信息集成方案的实现.     

基于OWL的本体集成

提出一种新的本体集成方法。分析了本体集成的原因,阐述了本体集成时应遵循的4条基本原则,并给出了集成的分类,提出了一种基于OWL DL图闭包的本体集成方法。该方法将OWL DL本体抽象为RDFS图模型,根据给定的OWL DL推理规则生成OWL DL本体的图闭包,在此基础上进行本体集成,同时提出了几种计算实体相似度的方法,将本方法与COMA++和FCA-merge进行实验对比,本方法在准确率和召回率上占优势。     

Numerical integration on a tetrahedron

Generalizing toR ³ a previous work inR ² [1], we give approximations with any arbitrary degree, of integrals on a tetrahedron, as a product (different from Stroud's conical product formulas) of one dimensional Gauss-Jacobi formulas.     

巢湖水体悬浮物的遥感分析

利用Landsat TM/ETM 卫星遥感影像为数据源,根据TM/ETM 的3、4波段反射率与悬浮物浓度存在着线性相关的性质,利用每个时相的3、4波段进行加法运算后的影像,对巢湖悬浮物浓度分布及其变化趋势进行了分析。研究结果表明,巢湖的悬浮物浓度较高,所占的面积在增大,悬浮物的污染还是很严重;但是,通过对1987年和2003年巢湖水体悬浮物悬浓度等级变化转移矩阵分析发现,悬浮物浓度等级降低的区域比悬浮物浓度等级升高的区域高出了17.64个百分点。这说明巢湖悬浮物的污染在减轻,国家对巢湖的治理已见成效。     

Democratic integration: self-organized integration of adaptive cues

Sensory integration or sensor fusion -- the integration of information from different modalities, cues, or sensors -- is among the most fundamental problems of perception in biological and artificial systems. We propose a new architecture for adaptively integrating different cues in a self-organized manner. In Democratic Integration different cues agree on a result, and each cue adapts toward the result agreed on. In particular, discordant cues are quickly suppressed and recalibrated, while cues having been consistent with the result in the recent past are given a higher weight in the future. The architecture is tested in a face tracking scenario. Experiments show its robustness with respect to sudden changes in the environment as long as the changes disrupt only a minority of cues at the same time, although all cues may be disrupted at one time or another.     

悬浮泥沙的计算机特征提取和分类

本文提出了一套适应于小型图象处理设备的信息提取,聚类分析等悬浮泥沙处理方法,它简而易行,降低了处理成本.其基本思想,特别是通过分级聚类将多维问题近似地化简为一维问题,可同样地用于其它各种应用问题.文章最后简要报告了一些应用结果.     

基于递增方式的视点集成研究*

针对与视点集成相关的问题,首先讨论了基于开发关系的视点集成方式,然后提出了一种基于二元递增方式的视点集成过程;同时采用范畴理论对该集成过程进行了建模,有利于一般意义上进一步研究与视点集成相关的基本性质.