Preparation of nanometre size oxide particles using filter expansion aerosol generator

Crystalline zinc oxide particles of nanometre size (< 20 nm) particles were produced from a zinc acetate solution by using a filter expansion aerosol generator (FEAG). The FEAG is an aerosol generator that is operated at 60 torr reactor pressure and produces droplets of around 2 m. The shape of the particles produced by the FEAG were distinctively different from those produced by the ultrasonic spray source (USS). Results from scanning electron microscopy (SEM) and X-ray diffractometry (XRD) indicated that crystalline zinc oxide particles of nanometre size were produced at 600 °C in 0.02 s residence time. Weight loss of these particles, determined by thermogravimetric analysis (TGA), was 3 wt%. Based on the morphology change as a function of the reactor temperature and solute concentration, we proposed that the nanometre particles were formed by uniform precipitation at the drying stage and decomposition followed by disintegration into nanometre particles. It was also shown that exothermic decomposition of the solute was not required for the disintegration of the primary particles in the FEAG process. This result opened up an opportunity for producing carbon-free nanometre particles from nitrate salts by using the FEAG.     

Surface modification of polyetherurethaneureas and their antithrombogenicity

Polyetherurethaneurea (PU) films were treated by oxygen plasma discharge followed by acrylic acid (AA) grafting. The carboxyl groups of the AA-grafted PU (PU-AA) surface were coupled with bovine serum albumin and heparin via water soluble carbodiimide. Surface characterization of the modified PUs was carried out by attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy and electron spectroscopy for chemical analysis (ESCA). The amount of immobilized albumin and heparin on the PU surface was 1.8 and 1.5 g/cm², respectively, as determined by the dye interaction method. Interactions between the surface-modified PUs and blood components such as plasma proteins and platelets were investigated to evaluate the blood compatibility of the samples. Plasma recalcification time (PRT) and activated partial thromboplastin time (APTT) of the albumin-immobilized PU (PU-Al) were almost the same as those of PU, while platelets were less adhered on the PU-Al than on PU. On the other hand, PRT and APTT of the PU-He were significantly longer than those of the PU, PU-AA, and PU-Al. Moreover, adhesion of platelets was effectively suppressed on the PU-He, leading to good in vitro blood compatibility.     

A network-based mobility management scheme for future Internet

The current Internet was originally designed for “fixed” terminals and can hardly support mobility. It is necessary to develop new mobility management schemes for the future Internet. This paper proposes an Identifiers Separating and Mapping Scheme (ISMS), which is a candidate for the future Internet mobility management, and discusses the basic principles and detailed message flow. ISMS is a network-based mobility management scheme that takes advantage of the identity and location separation. The mobility entities in the core network are responsible for the location management. ISMS is designed to satisfy the requirements of faster handover, route optimism, advanced management, location privacy and security. The average handover delay of ISMS is on the order of milliseconds only, which is far smaller than that of Mobile IPv6. Analyses show that ISMS can reduce packet overhead on wireless channels. We build a prototype and perform some experiments. Results verify the feasibility of ISMS.     

Embedding multi-dimensional meshes into twisted cubes

The twisted cube is an important variant of the most popular hypercube network for parallel processing. In this paper, we consider the problem of embedding multi-dimensional meshes into twisted cubes in a systematic way. We present a recursive method for embedding a family of disjoint multi-dimensional meshes into a twisted cube with dilation 1 and expansion 1. We also prove that a single multi-dimensional mesh can be embedded into a twisted cube with dilation 2 and expansion 1. Our work extends some previously known results.     

智能型双电源开关控制器的设计

提出了一种以PIC16F884单片机为控制单元,以两台塑壳断路器双电源开关为控制对象的智能控制器的设计方案.介绍了控制器的工作原理和工作模式,并给出了硬件方案和软件设计思想以及抗干扰的方法.     

偏最小二乘方法在中药指纹图谱相似度研究中的应用

本文介绍了偏最小二乘作为1种新的方法应用于指纹图谱的相似度比较计算中.偏最小二乘方法通过从中药色谱或光谱数据中提取大量信息来预测出1个响应值.本文中利用偏最小二乘方法为基础来计算中药色谱指纹图谱的相似度.相比较于传统的相似度计算方法,上述方法得到的结果更加明确可靠,并且计算量少于其他算法.     

未雨绸缪 防患未然——“柔性测试”助力泛华测控提供高可靠性测试系统

<正>毋庸置疑,"可靠性"一直是评价电子产品性能的关键词之一,尤其在军工、航天等领域,产品的可靠性更是具有举足轻重的地位。一个细小器件的故障引发系统重大事故的案例屡见不鲜。随着人们对可靠性的重要性认识的不断提高,业内对可靠性理论及可靠性设计的研究也不断深入。12月2日,由中国电子     

The effect of the aspect ratio on the hydrophobicity of microstructured polydimethylsiloxane (PDMS) robust surfaces

In this study, we have designed and fabricated robust hydrophobic surfaces that are composed of various micropillar arrays and investigated the effect of the aspect ratio (feature height/feature size) of the micropillar on the wettability of the fabricated surfaces. The robust, micropillar-arrayed surfaces were designed to yield the same Wenzel and Cassie water contact angles (CAs). According to our design rule, one can achieve an enhanced hydrophobic surface by increasing the height of the micropillars. The designed hydrophobic surfaces were fabricated by polydimethylsiloxane (PDMS) replica molding with photolithographically micropatterned SU-8 masters. The hydrophobicity properties of the fabricated PDMS surfaces were fully characterized theoretically and experimentally. From the theoretical and experimental results, it was found that the micropillars of an intrinsically hydrophobic material with a high aspect ratio enhance the hydrophobicity of the surface by increasing the surface roughness (in view of the Wenzel state) and the opportunities for the entrapment of air beneath a water droplet (the Cassie state).     

Optimization of optical lens-controlled scanning electron microscopic resolution using generalized regression neural network and genetic algorithm

A scanning electron microscope (SEM) is a sophisticated equipment employed for fine imaging of a variety of surfaces. In this study, prediction models of SEM were constructed by using a generalized regression neural network (GRNN) and genetic algorithm (GA). The SEM components examined include condenser lens 1 and 2 and objective lens (coarse and fine) referred to as CL1, CL2, OL-Coarse, and OL-Fine. For a systematic modeling of SEM resolution (R), a face-centered Box–Wilson experiment was conducted. Two sets of data were collected with or without the adjustment of magnification. Root-mean-squared prediction error of optimized GRNN models are GA 0.481 and 1.96×10^-12 for non-adjusted and adjusted data, respectively. The optimized models demonstrated a much improved prediction over statistical regression models. The optimized models were used to optimize parameters particularly under best tuned SEM environment. For the variations in CL2 and OL-Coarse, the highest R could be achieved at all conditions except a larger CL2 either at smaller or larger OL-Coarse. For the variations in CL1 and CL2, the highest R was obtained at all conditions but larger CL2 and smaller CL1.     

齐次等式约束线性回归模型条件根方估计的效率

对齐次等式约束线性回归模型回归系数的约束最小二乘估计提出改进,引入一种估计的相对效率,证明在一定条件下,狭义条件根方估计、广义条件根方估计的效率均高于约束最小二乘估计的效率．