Rain depolarization measurement using INTELSAT-IV satellite in 4 GHz band at a low elevation angle

The degradation of cross polarization discrimination (XPD)due to rain has been measured at 4 GHz using the Indian Ocean INTELSAT-IV satellite at Yamaguchi in Japan, where the satellite elevation angle is as low as 9 degrees. Based on the data obtained from August 1975 to October 1976, this paper describes the analyses on the cumulative time distribution of XPD,the correlation of XPD degradation with surface rain rate and rain attenuation, and the duration characteristics of XPD degradation.     

Grating Lobe Suppression of Narrow-Wall Slotted Hollow Waveguide Millimeter-Wave Planar Antenna for Arbitrarily Linear Polarization

A high-gain and high-efficiency slotted waveguide planar antenna is developed in the millimeter-wave band. Forty-five degree inclined polarization is required for automotive radar systems. In the design of slotted waveguide array for arbitrarily linear polarization, slot spacing is one guide wavelength which is larger than a wavelength in free space. Consequently, grating lobes appear in the radiation pattern. So, we developed a slotted waveguide planar antenna composed of post-loaded narrow-wall slots and a single-layer alternating-phase feeding circuit. A planar antenna with suppressed grating lobes has been fabricated and its RF performance has been measured. The measured gain is 33.2 dBi and antenna efficiency is 56% at 76 GHz. Grating lobe level is -28.6 dB lower than main lobe level. Since the proposed structure remains simple, the antenna is expected to be manufactured by metal injection molding for low cost     

Effect of Monovalent Cation Additives on the γ-Al2O3-to-α-Al2O3 Phase Transition

The effect of monovalent cation addition on the γ-Al₂O₃-to-α-Al₂O₃ phase transition was investigated by differential thermal analysis, powder X-ray diffractometry, and specific-surface-area measurements. The cations Li⁺, Na⁺, Ag⁺, K⁺, Rb⁺, and Cs⁺ were added by an impregnation method, using the appropriate nitrate solution. β-Al₂O₃ was the crystalline aluminate phase that formed by reaction between these additives and Al₂O₃ in the vicinity of the γ-to-α-Al₂O₃ transition temperature, with the exception of Li⁺. The transition temperature increased as the ionic radii of the additive increased. The change in specific surface area of these samples after heat treatment showed a trend similar to that of the phase-transition temperature. Thus, Cs⁺ was concluded to be the most effective of the present monovalent additives for enhancing the thermal stability of γ-Al₂O₃. Because the order of the phase-transition temperature coincided with that of the formation temperature of β-Al₂O₃ in these samples, suppression of ionic diffusion in γ-Al₂O₃ by the amorphous phase containing the added cations must have played an important role in retarding the transition to α-Al₂O₃. Larger cations suppressed the diffusion reaction more effectively.     

Backmixing of liquid in horizontal multiple-impeller vessels

The batch mixing model for liquid as the continuous phase of a gas-liquid system in a horizontal multiple-impeller vessel was applied to continuous flow operation. The back flow ratio was determined by measuring the residence time distribution. The relation between back flow ratio and operating variables was found to be similar to that for a vertical multiple-impeller vessel. A method for estimating the back flow ratio in a horizontal multiple-impeller vessel, from the mixing time in a single-impeller vessel, was presented.     

Addition of fentanyl to epidural lidocaine raises the toe temperature

In order to investigate effects of addition of fentanyl epidurally on the onset of sympathectomy from epidural lidocaine, we have measured the toe temperature of 29 healthy patients undergoing elective lower extremity or lower abdominal surgeries. The latency of onset of the toe temperature was significantly shorter in patients receiving both epidural lidocaine and fentanyl compared with those receiving epidural lidocaine alone (258 +/- 135 vs 398 +/- 184 sec, P < 0.05 [mean +/- SD]). Osmolarity and pH of the epidural solutions were similar between the two groups. These results suggest, but do not indicate, that sympathectomy from epidural lidocaine is accelerated by the addition of fentanyl.     

Preparation of Bi,Pb-Sr-Ca-Cu-O superconductor by the sol-gel method

The high -T _c superconducting phase in the Bi, Pb-Sr-Ca-Cu-O system has been prepared by the sol-gel method. The formation process of the low-T _c phase as well as the high-T _c phase has been examined by thermal analysis, infra-red measurements and X-ray diffraction, and compared with the conventional solid-state reaction. At a low heat-treatment temperature of 400 ° C, Bi₂O₃, CaCO₃ and CuO are precipitated from the gel. These oxides react with each other to form several double oxides above 600 ° C and yield the low-T _c phase as a main product at 800 ° C. The heat treatment at higher temperatures effectively leads to the formation of the high-T _c phase. In particular, the high-T _c phase is most predominantly formed in the specimen heat treated at 845 ° C for 48 h after calcination at 800 ° C for 12 h, which is reflected in the critical temperature of 104 K. The temperature at which the low-T _c phase is formed is lower in the sol-gel-derived sample than in the specimen prepared by the solid-state reaction. Further-more, the sol-gel method brought about a larger amount of the high-T _c phase than the solid-state reaction when the conditions for the heat treatment were identical. These facts clearly indicate the superiority of the sol-gel method for the formation of both high-T _c and low-T _c Bi, Pb-Sr-Ca-Cu-O superconducting phases.     

Self-assembly of concentric quantum double rings

We demonstrate the self-assembled formation of concentric quantum double rings with high uniformity and excellent rotational symmetry using the droplet epitaxy technique. Varying the growth process conditions can control each ring's size. Photoluminescence spectra emitted from an individual quantum ring complex show peculiar quantized levels that are specified by the carriers' orbital trajectories.     

Carbon–carbon composite bearing materials in hip arthroplasty: analysis of wear and biological response to wear debris

Ultra-high molecular weight polyethylene wear particles have been implicated as the major cause of osteolysis, implant loosening and late aseptic failure in total hip arthroplasties in vivo. This study initially screened 22 carbon-carbon composite materials as alternatives for UHMWPE in joint bearings. New bearing materials should satisfy certain criteria--they should have good wear properties that at least match UHMWPE, and produce wear particles with low levels of cytotoxic and osteolytic activity. Initial screening was based on wear resistance determined in short-term tribological pin-on-plate tests. Three materials (HMU-PP(s), HMU-RC-P(s), and SMS-RC-P(s)) which had superior wear resistance were selected for long-term testing. All materials had very low wear factors and SMS-RC-P(s), which had a wear factor of 0.08 +/- 0.56 x 10(-7) mm3/Nm, was selected for the subsequent biological testing and particle size analysis. SMS-RC-P(s) showed good biocompatibility in bulk material form and also the wear particles had low cytotoxicity for L929 fibroblasts in culture compared to metal wear particles. Wear debris size analysis by transmission electron microscopy showed that the particles were very small, with the vast majority being under 100 nm in size, similar to metal wear particles. The potential osteolytic effect of SMS-RC-P(s) wear particles was investigated by culturing particles with human peripheral blood mononuclear cells and measuring TNFalpha production. SMS-RC-P(s) did not significantly stimulate TNFalpha production at a particle volume to cell number ratio of 80:1, indicating that the debris had a low osteolytic potential. The results of this study suggest that carbon-carbon composites, particularly those composed of PAN-based fibers may be important biomaterials in the development of next generation bearing surfaces for use in total joint replacements that have very low wear rates and reduced osteolytic and cytotoxic potential.     

固体废弃物在超/近临界水中连续分解装置的研制

利用超／近临界水具有的特性,探索固体废弃物在超／近临界水中的再资源化技术。由于固体废弃物料在高温高压水中连续分解的反应装置。固体物料与水混成浆料供给反应器,解决了某些固体物料向高温高压反应器中的连续输送问题,浆料的固含量可达10％（wt）以上。并对模式物质——纤维素和木质素;实物——米糠、豆腐渣和稻壳等进行了连续分解实验,运行结果稳定。本工作证实了通过将固体废弃物与水混成浆料的方式,实现固体废弃物在超／近临界水中连续处理的可能性。