Hydrogen absorption by Pd-coated ZrNi prepared by using Barrel-Sputtering System

To improve the durability of hydrogen storage materials against surface poisoning by impurity gases, effectiveness of Pd-coating layer prepared by using a Barrel-Sputtering System was examined for ZrNi powder. The effectiveness of Pd-coating was evaluated by activation temperature, at which Pd/ZrNi poisoned by air could be activated to absorb hydrogen. Characterization of Pd-coated ZrNi (denoted as Pd/ZrNi) by scanning electron microscopy, electron probe microanalysis and X-ray diffraction showed that a uniform Pd-coating layer was formed with the barrel-sputtering system. It was found that the poisoned Pd/ZrNi sample could be activated even at 423 K to absorb hydrogen at room temperature. This exhibits remarkable contrast to bare ZrNi, which could be only activated appreciably above 1073 K. It is concluded that the Pd-coating by barrel sputtering is quite effective to avoid the effect of surface poisoning of powdery hydrogen storage materials. However, the activation at excessively high temperature resulted in the loss of high activity to absorb hydrogen. It was concluded that this phenomenon was associated with reactions between Pd and ZrNi to form PdZr and other byproducts.     

分割电极片状压电致动器——(二)位移特性及狭缝宽度对其影响的实验研究

研究了悬臂梁式分割电极片状压电致动器的位移特性。理论分析表明，分割电极狭缝宽度会减小致动器自由端的位移输出，但当狭缝宽度小于致动器电极宽度的１０％时，可忽略狭缝宽度的影响。致动器端部位移的测试结果大于理论计算值。与现有磁头悬浮臂尺寸相近的致动器，在２０Ｖ～５０Ｖ的电压驱动下均可获得１μｍ～２μｍ的致动位移。对９８５０道／厘米的密度磁盘，该位移能覆盖至少一个磁道宽度，满足磁头定位两级伺服系统对第二级致动器位移的基本要求。     

The material properties of sulphonated phenolic resin reinforced cement mortars

The material properties of new sulphonated phenolic resin (SP) reinforced cement mortars have been investigated. SP was found to promote the dispersion of cement particles and to interact with Ca(OH)₂. As a result, the resulting mortars exhibit better workability, more compact structure and higher compressive strength than plain mortars. The mortar with 1 wt% SP present after 28 days curing exhibits a compressive strength of 66MPa, which is about 18% higher than that of plain mortar.     

Computer processing of artifact and arrhythmias in heart rate variability analysis.

Analysis of heart rate variability (HRV) with Holter monitoring is often difficult due to excessive artifacts and arrhythmias. While short sudden surges are treated successfully by most methods, slow heart rate (HR) variations, nocturnal trapezoidally-shaped HR increases and special types of arrhythmias which are similar to normal HRV fluctuations may distort further time domain and spectral analysis. This paper examines the advantages and disadvantages of different methods for preprocessing of HR data. We have developed the following approach to the analysis of HRV. (1) A combination method based on the absolute difference between HR values and both the last normal HR value and an updated mean is used for removal of artifacts and arrhythmias. This method can detect both sudden surges in HR values as well as longer periods of noise combined with slow normal variations. An additional stage of wild point removal is then optionally applied. (2) Certain special problems such as large T-waves, bigeminal rhythm, slow HR variations and nocturnal trapezoidally-shaped HR increases are also identified. Although none of the algorithms can be applied successfully to all cases, the final computer analysis for preprocessing described in the present study has proved to be superior to the simplified methods which are usually used and provides more suitable data for HRV analysis.     

A hybrid wafer-dicing process for GaAs MMIC production

A dicing process for GaAs MMIC (monolithic microwave integrated circuit) wafers using spin-on wax for wafer mounting and a hybrid process of wet chemical etching/mechanical sawing for chip dicing is described. This process minimizes ragged chip edges and reduces generation of microcracks in addition to the elimination of the plated gold burrs on the backside of the diced MMIC chips. This process gives a uniformity of -3 μm across a 2-in wafer following the completion of the whole backside process. This GaAs chip dicing technique is amenable to production because it exhibits both a very high chip yield (>90%) and nearly flawless edges     

Development of a distributed sensing technique using Brillouinscattering

This paper reviews the developments of a distributed strain and temperature sensing technique that uses Brillouin scattering in single-mode optical fibers. This technique is based on strain- and temperature-induced changes in the Brillouin frequency shift. Several approaches for measuring the weak Brillouin line are compared     

Integrated-optic double-ring resonators with a wide free spectralrange of 100 GHz

Integrated-optic double-ring resonators with a wide free spectral range (FSR) of 100 GHz are fabricated using GeO₂-doped silica waveguides with a high relative refractive index difference (Δ) of 1.5%. The resonators are composed of two ring resonators comprising small ring waveguides with radii of 1.75 and 2.0 mm. The double-ring resonator module exhibited a wide FSR of 98.0 GHz, a finesse of higher than 138, a low crosstalk of less than -11.7 dB, and a low insertion loss of 6.1 dB. The measured FSR of 98.0 GHz is wider than any previously reported ring resonator composed of optical waveguides     

Synthesis, characteristics and oxygen-sensitive properties of SrMgxTi 1 − xO3 nanocrystals

SrMg_xTi_{1 - x}O₃ nanocrystals (x = 0.1–0.6) were synthesized by the stearic acid gel method. Powder samples were characterized by X-ray diffraction and X-ray photoelectron (XP) spectroscopy. The results showed that the lattice parameter a and the O 1s XP spectrum changed not only with the Mg content x but also with the grain size d of the samples. The conductivity of a thick film specimen fabricated on an aluminium oxide wafer was investigated in a nitrogen—oxygen atmosphere.     

Pore size control of porous silica by sol-gel process

Porous silica glass was prepared by sol-gel process from tetraethoxysilane (TEOS). The effects of solvents (water, ethanol), drying condition, heat treatment temperature on specific surface area and pore size distribution of porous silica were investigated. Gelation process accelerates with an increase of H₂O content, while retards with the increase of ethanol amount. Structure changes during heat treatment were studied by means of DTA, XRD. TEM micrographs show that the gel particles shrink after heated at 500°C, thus the average pore size decreases.