The electrode system in impedance-based ventilation measurement

In this paper, we determined which electrode types, sizes, and locations were best suited for impedance-based ventilation measurement. Optimal electrodes provide high signal-to-(motion) artifact ratio (SAR) and reliability by meeting the following criteria: 1) low baseline impedance, 2) high adhesion, 3) good physical stability, 4) large effective area, 5) thin with high flexibility. We compared 14 electrodes from two main groups: adhesive-gel and conductive rubber electrodes. Adhesive-gel electrodes are easy to apply, make good body contact, and do not slip during the course of an experiment. We found that higher SAR's are obtained when electrode area is increased by connecting several small electrodes together rather than by using a single electrode with a larger area. The peak SAR is achieved when two electrode arrays (area = 70 cm2) are centered at the 8th intercostal spaces on opposite midaxillary lines. To determine the optimal electrode locations, we placed 32 electrodes on the trunk and recorded impedance between 171 electrode combinations on ten normal adult subjects. Based on these data, we conclude that the SAR's are highest when one electrode is placed on the midpoint between the left and right second intercostal spaces on the sternum and the other electrode is placed in the opposite position on the back.     

Optimization of grating duty factor in gain-coupled DFB lasers withabsorptive grating-analysis and fabrication

Grating duty factor strongly affects the performance of gain-coupled (GC) distributed feedback (DFB) laser diodes with an absorptive grating. Through numerical analysis the authors have found an optimum value in the duty factor for their low threshold operation. The minimum threshold gain achievable at this optimum duty factor is found to be almost independent of the order of the grating. According to this prediction, the authors have fabricated GaAlAs/GaAs GC DFB lasers with a third-order absorptive grating where the grating duty factor has been made close to the theoretical optimum value. In 200-μm-long devices with both facets as-cleaved, low CW threshold current of 25 mA, external efficiency of 0.5 mW/mA, and SMSR as high as 45 dB have been obtained, which is qualitatively consistent with the analysis. High yield of single mode oscillation seems to be the result of the gain coupling     

High-temperature performance and microstructure of composite modified hard asphalt

Composite modified hard asphalt (CMHA) was prepared by four-step high-speed shearing method adding crumb rubber, styrene-butadiene-styrene (SBS) copolymer, and hard asphalt to QHD AH-70 neat asphalt. The high-temperature performance and microstructure of CMHA were evaluated by rotational viscometer, fluorescence microscopy, and infrared spectroscopy, through which the modification mechanism was proposed. The results show that the shearing time had great influence on the high-temperature performance of CMHA. A significant variation in phase morphology of CMHA during preparation was observed. It is found that phase morphology was converted from a continuous asphalt phase with dispersed polymer phase to two twisted continuous phases, then to a continuous asphalt phase with dispersed polymer phase again. Preparation of CMHA was a complex physical and chemical process. A fraction of SBS took part in the chemical reaction and others were dispersed in net structure, which is beneficial for workability and performance of asphalt.     

钛合金的激光气体氮化研究

本研究了Ｔｉ－６Ａｌ－４Ｖ合金的激光气体氮化，试验结果表明在激光功率密度大于５．０×１０＾４Ｗ／ｃｍ＾２，氮气压力为０．４ＭＰａ，通过激光辐射可在Ｔｉ－６Ａｌ－４Ｖ合金表面形成氮化钛。其氮化层的厚度为４００μｍ。在氮化层中存在大量氮化钛枝晶。其平均二次枝晶间距为１．７７μｍ。细小的氮化钛枝晶均匀地分布在氮化层中。最后测定和分析了氮化层的显微组织、相成份和显微硬度，并讨论了氮化钛的形成过程。     

Iterative boundary condition (IBC) in finite difference solvingscattering problems of open region

A novel truncation boundary condition, the iterative boundary condition (IBC), is proposed for finite difference (FD) solving electromagnetic scattering problems. The iterative process of this condition is given. Solutions of the IBC for some 2D cylinder scattering problems have been obtained and are compared with solutions using MoM and MEI. These solutions show very good agreement     

硬限幅函数神经元的精确实现

本文提出了一种新的利用跨导运放ＯＴＡ精确实现电压－电流型硬限幅函数神经元方法，它的主要特点是容易实现、且神经元的输幅可调。     

增产措施选井方法

增产措施选井方法以试井手段为主，结合油藏工程方法，综合考虑了决定措施效果的各种因素，建立了措施选井的基本模式。该技术经中原油田上百井次的应用，选井准确率达80％以上，验证了该方法的可行性。     

川东北气区高含硫天然气开发SWOT分析

利用SWOT态势分析方法,对四川盆地川东北气区高含硫天然气开发所拥有的资源、发展环境等优势和勘探开发、工艺技术等方面的劣势进行分析,指出当前川东北高含硫天然气开发的条件、机遇和不足,并从政治法律、经济、社会文化和技术等外部环境以及天然气经营潜在进入者和竞争对手等外部威胁分析其对本企业的影响和不利,在此基础上提出了加快川东北高含硫天然气开发的建议。     

Effect of organic/inorganic coating on moisture diffusion in a chip-on-board package with globtop

The moisture diffusion in globtop material for a chip-on-board (COB) package coated with SiN_x and silicone, respectively, or coated with SiN_x plus silicone were measured by embedding a humidity sensor in the globtop and recording the capacitive change in three different temperature/humidity environments. The experimental results were simulated by Fick’s diffusion law with finite-element method modeling. The moisture diffusion coefficients and activation energies were calculated to quantitatively compare the moisture-resistance effects of different coatings. For example, at 85°C/85% RH, the moisture diffusion coefficients for the uncoated reference, SiN_x-coated, silicone-coated, and silicone/SiN_x double-layered coated samples are 1E-5, 0.8E-5, 0.7E-5, and 0.2E-5 mm²/s, respectively. The experimental and simulation results show that double-layered coating with silicone/SiN_x has excellent moisture-resistance properties because it not only smoothes the steps on a printed circuit board (PCB) but also keeps the good moisture resistance of the inorganic films.