An Integrated Sideband-Separating SIS Mixer Based on Waveguide Split Block for 100 GHz Band with 4.0–8.0 GHz IF

We have developed an integrated sideband-separating SIS mixer for the 100 GHz band based on the waveguide split block. The measured receiver noise temperatures with 4.0–8.0 GHz IF are less than 60 K in the LO frequency range of 90–110 GHz, and a minimum value of around 45 K is achieved at 100 GHz. The image rejection ratios are more than 10 dB in the frequency range of 90–110 GHz. We have installed the sideband-separating SIS mixer into an atmospheric ozone-measuring system at Osaka Prefecture University and successfully observed an ozone spectrum at 110 GHz in SSB mode. This experimental result indicates that the sideband-separating SIS mixer is very useful for astronomical observation as well as atmospheric observation.     

Vacuum Ultraviolet Spectra of Silver in a Borosilicate Glass

Vacuum ultraviolet absorption spectra of silver dissolved in 60 mol% B₂O₃-40 mol% SiO₂ glass in oxygen, nitrogen, and oxygen–nitrogen atmospheres at 1000°, 1100°, and 1200°C were measured. Strong absorption which may be attributed to Ag⁺-complex was observed around 5.5 and 6.5 eV. It is suggested that an Ag⁺-complex/Ag⁰ redox pair exists in the glass and that this pair shows O-type redox behavior.     

An improved procedure for the detritylation of 1-alkyl 2-acyl 3-trityl-sn-glycerols

The effects of experimental conditions and acid catalysts on the removal of the trityl group of 1-alkyl-2-acyl-3-trityl-sn-glycerols to yield 1-alkyl-2-acyl-sn-glycerols have been investigated. Removal of the trityl protecting group was complicated by the concomitant migration of the 2-acyl moiety to yield the 1-alkyl-3-acyl-sn-glycerol isomer. The course of detritylation as well as the extent of the 2-acyl to 3-acyl migration under the various conditions used were followed by high performance liquid chromatography (HPLC). Optimum yields of the desired 1-alkyl-2-acyl-sn-glycerol (}90%) were obtained with a molar equivalent of boron trifluoride-methanol in methylene chloride at 22 C for five min. Presented in part at the AOCS meeting in Honolulu, Hawaii, in May 1986.     

A biologically plausible neural network for motion detection

A neural network model is proposed that detects the actual velocity vector of an object by using local motion signals detected by local motion detectors. First, the computational theory to obtain the actual velocity vector of a rigid object is described. Then a neural network is shown that implements the theory. The neural network model is constructed by two layers: a local velocity vector extraction layer and an integration layer. Many velocity vectors of points on a moving object are detected by local detectors in the local velocity vector extraction layer. These local velocity vectors are integrated in the integration layer in order to obtain the actual velocity vector of the object. The computational processing pathway of the proposed model is similar to the motion processing pathway of visual stimulus in the actual nervous system.     

Preferred orientation of AlN plates prepared by chemical vapour deposition of AlCl3 + NH3 system

Aluminium nitride (AlN) plates about 1 mm thick (maximum) were prepared by chemical vapour deposition (CVD) at the maximum deposition rate of 430 nm s⁻¹ using AlCl₃, NH₃ and H₂ gases at deposition temperatures,T _dep, of 873–1473 K. The effects of deposition conditions on the preferred orientation, morphology and micro-structure were investigated. WhenT _dep was less than 1073 K, the resulting CVD AlN plates contained some impurity chlorine and the aluminium content exceed the nitrogen content. WhenT _dep exceeded 1173 K, no chlorine was detected, and the Al/N atomic ratio matched the stoichiometric value. The lattice parameters (a=0.311 nm,c=0.4979 nm) and density (3.26×10³ kgm⁻³) were in agreement with values reported previously. The crystal planes oriented parallel to the substrates changed from (1 1 ˉ2 0) to (1 0 ˉ1 0) to (0001) with increasing total gas pressure (P _tot) and decreasingT _dep. This tendency is discussed thermodynamically and is explained by the change of supersaturation in the gas phase.     

Coating of titanium carbide films on stainless steel by chemical vapour deposition and their corrosion behaviour in a Br2-O2-Ar atmosphere

Stainless steel (SUS304) plates were coated with TiC films using chemical vapour deposition (CVD) as a candidate material for UT-3 which is a promising process of hydrogen production through the thermal decomposition of water. The corrosion behaviour of the TiC film-coated SUS304 plates was examined in a Br₂-O₂-Ar atmosphere. The effects of CVD conditions on the surface texture, deposition rates and preferred orientation of the TiC films were investigated, and the optimum CVD conditions determined. Corrosion of the TiC film-coated SUS304 plates in the Br₂-O₂-Ar atmosphere was mainly caused by oxidation of the TiC film and SUS304 substrate. Microcracks in the TiC films lead to corrosion of the SUS304 substrate. At oxygen partial pressures below 0.1 kPa, weight loss was observed due to the formation of volatile titanium and iron bromides. At oxygen partial pressures greater 0.1 kPa, the time dependence of weight increase was parabolic due to the formation of oxide scale. The oxide scales were mixtures of TiO₂, Fe₂O₃ and Fe₃O₄. The corrosion mechanism is discussed thermodynamically.     

New materials in automotive tribology

The rapid, world‐wide spread of automobiles has necessitated the development of improved technologies for environmental protection, resource utilization and customer satisfaction. As the designs of automotive components have changed, emphasis has shifted to tribological approaches. New tribo‐materials are needed for automotive components that must run at higher temperatures and higher [pressure] x.[velocity] conditions. This paper outlines current issues related to tribo‐materials in passenger cars. This revised version was published online in June 2006 with corrections to the Cover Date.     

Studies on the friction and transfer of semicrystalline polymers

The friction and transfer of various semi-crystalline polymers were studied in several experiments. The cylindrical surfaces of polymers were slid over glass plates at low speed and under constant load. The kinetic friction of PTFE in repeated traverses did not vary with the number of traverses and the transfer of PTFE occurred successively on previously transferred PTFE films. The film transferred at each traverse was extremely thin (< 50 Å). The friction of PTFE decreased with increased humidity in the environment and appeared to be independent of crystalline transitions. Other polymers exhibited higher friction than PTFE and their transfer was generally as small lumps or short streaks. HDPE displayed a very low friction, although the friction of ultrahigh molecular weight polyethylene (UHDPE) was somewhat higher than that of HDPE. With HDPE and UHDPE, as well as with PTFE, long films stretched from one side of the abrasion grooves produced on the polymer frictional surfaces to the other side, like a bridge. The static friction of the three different polymers was very sensitive to the direction of prerubbing on the frictional surfaces and the static friction in sliding parallel to the pre-rubbing direction was much smaller than that perpendicular to it. The roles of the molecular profile and of the banded or spherulitic structure of the polymers in the polymer transfer mechanism are discussed on the basis of the experimental results obtained.     

Viscoelastic-plastic behaviour with mean strain changes in polypropylene

The stress-strain curves and stress-relaxation curves of polypropylene are obtained by using a closed-loop, electrohydraulic, servo-controlled testing machine. Effects of mean strain changes on deformation behaviour are examined in a tension-compression mode under strain control at room temperature (18–23 °C). The hysteresis loops of three mean strains show a steady-state response from the stress-strain curves at a strain rate of 1 × 10^–3 s^–1 at a strain width of 5%, at a number of cycles of N=50 and at three mean strains (_m=0, + 1.0 and + 2.0%). The drop of stress at the mean strain of _m= -1.0% is larger in magnitude than that at _m=+1.0%; this is caused by the higher stress level at _m=- 1.0% as compared with the stress level at _m=+1.0%. From the results of stress amplitude and the stress drop behaviour, the magnitude of stress drop is hardly affected by the mean strain.     

Wafer-level vacuum package of two-dimensional micro-scanner

Microsystem Technologies - We present wafer-level vacuum package of two-dimensional (2-D) micro-scanner based on glass-silicon anodic bonding. To form the sacrificial gap for evacuating air in the...