基于SOI-MEMS技术的静电驱动-电容检测硅谐振器

提出一种基于SOI-MEMS技术的静电驱动-电容敏感检测的横向硅谐振器,对其进行设计、MEMS工艺加工制作实现、微弱电容检测及开环测试．该新型静电激励谐振器结构主要包含一个从中间受力点向两侧引出两个电极板的双端固支梁,这种设计使得此谐振器的静电驱动电压远小于具有相同电极板面积和极板间距的同类静电驱动谐振器,且检测电容更大,降低了检测难度．以器件层电阻率很低（0．001～0．002Ω·bcm）的SOI晶圆为基础材料,其SOI—MEMS加工工艺流程简单,仅需要2块掩膜版,有4个主要单步工艺．实验测试结果表明：在真空度为0．1—1．0Pa环境下,直流偏置电压低至30V,交流驱动电压峰-峰值为20mV时,该谐振器在其谐振频率点52261．99Hz处的Q值依然高于11800．     

Effects of Minerals on the Release of Nitrogen Species from Anthracite

Abstract

Experiments have been carried out to investigate the effects of minerals on nitrogen species emission including NO and its precursors from a high rank coal during temperature-programmed combustion by TG/EGA method at 10°C/min. Sodium was found to be an excellent catalyst for the reduction of NO and HCN evolution due to its higher catalysis of sodium on the char-NO reaction. However, iron can induce an increase of NO release. Calcium and titanium additives can be classified as inactive constituents because of their weak catalysis on HCN and NO emission. All the metallic additives can promote NH₃ emission except sodium. Parent coal has higher fractions of nitrogen release as NO and NH₃ and lower fraction of nitrogen release as HCN than demineralized coal, which can be attributed to the catalysis of indigenous minerals in parent coal.     

Multi-degree cyclic hoist scheduling with time window constraints

This paper deals with the multi-degree cyclic single-hoist scheduling problem with time window constraints, in which multiple identical parts enter and leave the system during each cycle. We propose an analytical mathematical model and a branch-and-bound algorithm so as to find a cyclic sequence of hoist moves that maximises the throughput. The branch-and-bound algorithm implicitly enumerates the sequence of hoist moves and requires the solution of a specific set of linear programming problems (LPPs). Computational results on benchmark instances and randomly generated test instances are presented.     

High-performance EPDM/organoclay nanocomposites by melt extrusion

Ethylene-propylene-diene terpolymer (EPDM)/organoclay nanocomposites were prepared by melt extrusion in a twin-screw extruder. The organoclay was characterized by XRD and TGA. As observed by transmission electron microscopy (TEM), the organoclay particles were exfoliated in EPDM. The tensile strength of the nanocomposites increased to 12.3 MPa at the same 3.0 phr amounts of fillers, which was a five-fold increase compared to pure EPDM and 2.8 times compared to the nanocomposite prepared by direction blending; furthermore it was above that of carbon black composites with 15.0 phr. The results of co-reinforcement system exploited a promising application prospect of the organoclay and the nanocomposites. The processability of the terpolymer was improved as a result of the decrease of mooney viscosity; the improvement of the thermal stability of the nanocomposite was determined by TGA.     

FTIR Characterization of Fe3+–OH Groups in Fe–H–BEA Zeolite: Interaction with CO and NO

Fe³⁺–OH groups of a Fe–H–BEA sample prepared by conventional ion-exchange method are characterized by an IR band at 3686–3684 cm^?1. They exhibit a weak acidity: upon low-temperature CO adsorption the O–H stretching modes are blue shifted by 100 cm^?1 and the respective carbonyl adducts are observed at 2158 cm^?1. The Fe³⁺–OH groups are reduced at room temperature by NO to form Fe²⁺–NO species and NO⁺ groups in cationic positions. Desorption of pre-adsorbed NO at temperatures above 373 K regenerates the Fe³⁺–OH groups. The relation of the Fe³⁺–OH species to the so-called α-oxygen is discussed.     

One-dimensional self-assembly of planar pi-conjugated molecules: adaptable building blocks for organic nanodevices

In general, fabrication of well-defined organic nanowires or nanobelts with controllable size and morphology is not as advanced as for their inorganic counterparts. Whereas inorganic nanowires are widely exploited in optoelectronic nanodevices, there remains considerable untapped potential in the one-dimensional (1D) organic materials. This Account describes our recent progress and discoveries in the field of 1D self-assembly of planar pi-conjugated molecules and their application in various nanodevices including the optical and electrical sensors. The Account is aimed at providing new insights into how to combine elements of molecular design and engineering with materials fabrication to achieve properties and functions that are desirable for nanoscale optoelectronic applications. The goal of our research program is to advance the knowledge and develop a deeper understanding in the frontier area of 1D organic nanomaterials, for which several basic questions will be addressed: (1) How can one control and optimize the molecular arrangement by modifying the molecular structure? (2) What processing factors affect self-assembly and the final morphology of the fabricated nanomaterials; how can these factors be controlled to achieve the desired 1D nanomaterials, for example, nanowires or nanobelts? (3) How do the optoelectronic properties (e.g., emission, exciton migration, and charge transport) of the assembled materials depend on the molecular arrangement and the intermolecular interactions? (4) How can the inherent optoelectronic properties of the nanomaterials be correlated with applications in sensing, switching, and other types of optoelectronic devices? The results presented demonstrate the feasibility of controlling the morphology and molecular organization of 1D organic nanomaterials. Two types of molecules have been employed to explore the 1D self-assembly and the application in optoelectronic sensing: one is perylene tetracarboxylic diimide (PTCDI, n-type) and the other is arylene ethynylene macrocycle (AEM, p-type). The materials described in this project are uniquely multifunctional, combining the properties of nanoporosity, efficient exciton migration and charge transport, and strong interfacial interaction with the guest (target) molecules. We see this combination as enabling a range of important technological applications that demand tightly coupled interaction between matter, photons, and charge. Such applications may include optical sensing, electrical sensing, and polarized emission. Particularly, the well-defined nanowires fabricated in this study represent unique systems for investigating the dimensional confinement of the optoelectronic properties of organic semiconductors, such as linearly polarized emission, dimensionally confined exciton migration, and optimal pi-electronic coupling (favorable for charge transport). Combination of these properties will make the 1D self-assembly ideal for many orientation-sensitive applications, such as polarized light-emitting diodes and flat panel displays.     

Preparation and characterization of new anhydrous, conducting membranes based on composites of ionic liquid trifluoroacetic propylamine and polymers of sulfonated poly (ether ether) ketone or polyvinylidenefluoride

A novel ionic liquid of trifluoroacetic propylamine, i.e., [CH₃CH₂CH₂NH₃⁺] [CF₃COO⁻] (TFAPA), was synthesized from trifluoroacetic acid and propylamine. The ionic liquid of TFAPA was used to prepare anhydrous, conducting membranes based on polymers of sulfonated poly (ether ether) ketone (SPEEK) or polyvinylidenefluoride (PVDF). The ionic conductivity and mechanical strength of the composite membranes were investigated at elevated temperatures and under anhydrous conditions. Conductivity of 0.030 S/cm was achieved with TFAPA at 180 °C, and of 0.019 S/cm with a membrane containing 70% (wt) TFAPA in SPEEK with a sulfonation degree of 86% at 160 °C. Increasing either ionic liquid content or temperature reduced the mechanical strength of the composite membrane. Efforts were made to improve the strength of TFAPA/SPEEK composite membranes by cross-linking the SPEEK, which led to some strength enhancement at 110 °C and 130 °C.     

Thermally and mechanically enhanced epoxy resin‐silica hybrid materials containing primary amine‐modified silica nanoparticles

In this article, a series of hybrid materials consisted of epoxy resin matrix and well‐dispersed amino‐modified silica (denoted by AMS) nanoparticles were successfully prepared. First of all, the AMS nanoparticles were synthesized by performing the conventional acid‐catalyzed sol–gel reactions of tetraethyl orthosilicate (TEOS), which acts as acceded sol–gel precursor in the presence of 3‐aminopropyl trimethoxysilane (APTES), a silane coupling agent molecules. The as‐prepared AMS nanoparticles were then characterized by FTIR, ¹³C‐NMR, and ²⁹Si‐NMR spectroscopy. Subsequently, a series of hybrid materials were prepared by performing in situ thermal ring‐opening polymerization reactions of epoxy resin in the presence of as‐prepared AMS nanoparticles and raw silica (RS) particles (i.e., pristine silica). AMS nanoparticles were found to show better dispersion capability in the polymer matrices than that of RS particles based on the morphological observation of transmission electron microscopy (TEM) study. The better dispersion capability of AMS nanoparticles in hybrid materials was found to lead enhanced thermal, mechanical properties, reduced moisture absorption, and gas permeability based on the measurements of thermo gravimetric analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and gas permeability analysis (GPA), respectively. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

基于LabVIEW和PDA的模块化便携式车载检测仪设计

现代汽车机电一体化程度越来越高,其电气、动力、液压系统的结构与工作原理日趋复杂,司机单靠经验对汽车保养和简单维护将很难满足需求.于是迫切需要一种操作简单、便携且价格低廉的车载检测、诊断仪.基于PDA的廉价、便携及可靠性,结合NI公司的DAQCard-6024E数据采集卡和Lab-VIEW PDA模块,可以设计出满足以上需求的仪器.因其模块化及可订制的软件,这种检测仪具有很强的适应性,也可应用于汽修厂.进一步开发PDA的无线网络功能,还可使司机随时随地获得汽修厂专业在线支持,其市场前景广阔.     

基于ANSYS的套管螺纹应力分析

石油套管在井下受力复杂,其螺纹连接是套管的薄弱环节。在目前发现的套损中有很大的比例是由螺纹连接失效造成的,因此真实地模拟井下受力情况,并且准确的测出在不同工况与螺纹部位的应力应变场的关系,对研究套管螺纹连接的极限承载能力,保护套管,保证油田正常生产具有十分重要的意义。文章采用ANSYS软件提供的子模型方法,通过有限元分析方法研究套管螺纹受力状况及变形情况,模拟井下复杂工况环境对套管螺纹的影响,优化螺纹结构,使应力分布更加合理。