A design technique for a 60 GHz-bandwidth distributed basebandamplifier IC module

A DC-60 GHz, 9 dB distributed amplifier IC module is fabricated with 0.15 μm InAlAs-InGaAs low-noise HEMTs with 155 GHz f_T and 234 GHz f_max. The device is mounted in a metal package with 1.8 mm coaxial cable signal interfaces. The package is specially designed using three-dimensional electromagnetic field analyses, resulting in very flat frequency characteristics of the module within 1.5 dB gain ripples over the entire bandwidth. A multichip module loaded with two amplifier ICs in cascade is also fabricated, and operates at a 17.5 dB gain from 60 kHz to 48 GHz. The 1 dB gain compression output power is about 5 dBm for both modules. The noise figure of the single-chip module is approximately 4 dB over a 10-40 GHz frequency range     

Creep-fatigue failure test and analysis of a vessel-type structure subjected to cyclic thermal transients

A SUS 304 vessel type test model, designed to include several typical structural parts of FBR components, was subjected to 1,300 cycles of severe thermal transient loadings using a large scale sodium loop. After th test, the model was inspected by a dye penetrant test. Crackings were observed at the intended portions of the model, and the fracture surfaces were nearly perfect rock-candy patterns (IG crackings) which are usually observed in creep rupture crackings. A-Heat transfer analysis using the measured temperature data, and elastic and inelastic thermal stress analyses were carried out to evaluate the creep-fatigue damage and the crack initiation. Strain concentration factors due to geometrical and metallurgical discontinuities or to inelastic behavior of the material are discussed. Finally fracture mechanics analyses were performed to explain the crack growth behavior.     

Immunohistochemical studies of proliferating cell nuclear antigen and cathepsin D in transitional cell carcinoma of the urinary bladder

Immunohistochemical staining for proliferating cell nuclear antigen (PCNA) and cathepsin D was performed on 60 transitional cell carcinoma (TCC) specimens from 60 patients with bladder cancer. The percentage of PCNA-positive cells (PCNA-labelling index) was determined by counting 500 or 1,000 cells, and cathepsin D expression was graded according to the extent of immunoreactivity to anti-cathepsin D antibody. The PCNA-labelling index was significantly higher in high-grade and high-stage tumors compared to that in low-grade and low-stage tumors. Cathepsin D was highly positive in grade-1 tumors. In contrast, 82% of grade-3 tumors and 76% of advanced tumors showed negative or low reactivity to anti-cathepsin D. Groups of high PCNA-labelling index and negative cathepsin D had significantly poorer prognoses compared to those of the low PCNA group and cathepsin D highly positive group, respectively, in univariate analyses. However, neither of these two factors were independent prognostic factors in multivariate analyses. These results suggest that the PCNA-labelling index and cathepsin D expression may indicate the malignant potential of TCC and may be able to provide additional information for predicting survival when stratifying for grade of bladder cancer.     

Effects of pH and SO2 on solubility coefficients of inert gases in human whole blood

We systematically investigated the quantitative importance of pH and O2 saturation (SO2) of hemoglobin on the solubility coefficients (alpha) for six inert gases: sulfur hexafluoride, N2, ethane, cyclopropane, halothane, and diethyl ether. Measurements of alpha were made at 37 degrees C with SO2 of 0-1.0 and pH of 7.2-7.7 by use of whole blood obtained from three healthy subjects. No significant dependence of alpha on pH was demonstrated for sulfur hexafluoride, N2, halothane, or diethyl ether, but an appreciable augmentation of alpha with increasing pH was found for ethane and cyclopropane. No alpha value obtained for oxygenated blood differed statistically from that for deoxygenated blood. In addition to the basic findings on the effects of pH on alpha values of ethane and cyclopropane with the multiple inert gas elimination technique (data obtained from 22 patients with either interstitial pneumonia or chronic obstructive pulmonary disease), we also found that dependence of alpha on blood pH exerted no significant influence on the recovery of ventilation-perfusion distribution in the lung. We concluded that: 1) pH plays an appreciable role in determining gas solubilities in blood, 2) SO2 is not a decisive factor for gas solubilities in blood, and 3) the influence of various pH values in pulmonary capillaries on inert gas exchange is negligible.     

Development of railgun accelerator at the institute of space and astronautical science (ISAS)

This paper describes the current status of the development of electromagnetic launchers such as the railgun at ISAS. The railgun is the most improved accelerator of Electromagnetic Launchers (EML). EML offers a potential for accelerating a projectile to much greater velocities than achieved with conventional powder guns or light gas guns. However, there has been little progress in increasing the velocity of EMLs since the experiment by Rashleigh and Marshall. A few experiments have been reported achieving velocities greater than 6km/s. The authors have achieved velocities greater than 6 km/s by reducing plasma leakage which is one of the factors limiting velocity. In this paper a 6 km/s launch is reported, compared with the results of two other shots considered from the viewpoint of plasma leakage, and the effect of entrainment of eroded material into the armature by rail ablation was discussed on the basis of simulated numerical calculations.     

On the formulation of optimal water allocation problem by linear programming

A problem of maximizing the efficiency of water use in industry is considered as a problem of optimizing water allocation in a total system which consists of water using and treating sub-systems. A problem formulation presented here is directed toward the iterative use of the linear programming based on characteristics specific to water allocation problems.     

Over-60-GHz design technology for an SCFL dynamic frequency dividerusing InP-based HEMTs

A toggle operation of 39-63.5 GHz without tuning has been achieved by a digital dynamic frequency divider (DFD). The DFD employs a pair of clocked inverters (CIs) with source-coupled FET logic (SCFL) and uses 0.1-μm-gate InAlAs/InGaAs/InP high electron-mobility transistors (HEMTs) of good uniformity and high performance. On a 2-in wafer, the frequency divider showed a maximum toggle frequency (f_tog,max) of 59.1±3.3 GHz and a fabrication yield of 89%. This is the highest operation frequency ever reported for a broad-band digital frequency divider. Comparison of the DFD and the static frequency divider (SFD) showed that the ratio of f_tog,max for the DFD to that for the SFD is much higher than the value expected from the linear-response theory. The comparison also showed that the ratio of the measured f_tog,max for the DFD to that for the SFD is 1.7, in contrast with the value of two expected from the circuit simulation. Delay-time analysis revealed that this 15% decrease of the ratio is due to the transmission delay of interconnections and charging time for stray capacitance     

Caution when applying eddy current inversion to stress corrosion cracking

This study evaluates the applicability of computer-aided eddy current inversion techniques to the profile evaluation of stress corrosion cracking in Inconel welds. Welded plate specimens, which model head penetration welds of pressurized water reactors, are fabricated; notches and stress corrosion cracks are artificially introduced into the weld metal of the specimens. Eddy current inspections are performed using a uniform eddy current probe driven at frequencies of 10 and 40 kHz. Since weld noise is observed uniformly along the weld line, a simple signal processing is applied to eliminate it. First, the artificial notches are reconstructed and good agreements between reconstructed and true profiles are provided, which demonstrates that the computer-aided eddy current inversion technique can deal with defects in welds. Then, numerical simulations are performed to evaluate the profiles of the stress corrosion cracks. In the numerical simulations, the stress corrosion cracks are modeled as a conductive region with a fixed width of 0.3 mm. The cross-sectional profiles of the cracks are reconstructed from measured eddy current signals directly above and along a crack. Although eddy current signals calculated from the reconstructed profiles agree well with measured ones, the true profiles revealed by destructive testing are found to be very different from the reconstructed ones. Whereas the most plausible reason for the difference is the unexpectedly volumetric profile of the stress corrosion cracks, this study has revealed that computer-aided eddy current inversion techniques that have been used to consider cracks in thin structures would not at this point be directly applicable to those in thick structures. It is also important to know in advance those crack features that can adversely impact accurate crack sizing including whether a detected crack is volumetric or not, namely there are many parallel cracks in a cluster or not.     

Highly spin-polarized materials and devices for spintronics?

The performance of spintronics depends on the spin polarization of the current. In this study half-metallic Co-based full-Heusler alloys and a spin filtering device (SFD) using a ferromagnetic barrier have been investigated as highly spin-polarized current sources. The multilayers were prepared by magnetron sputtering in an ultrahigh vacuum and microfabricated using photolithography and Ar ion etching. We investigated two systems of Co-based full-Heusler alloys, Co₂Cr_{1 − x}Fe_xAl (CCFA(x)) and Co₂FeSi_{1 − x}Al_x (CFSA(x)) and revealed the structure and magnetic and transport properties. We demonstrated giant tunnel magnetoresistance (TMR) of up to 220% at room temperature and 390% at 5 K for the magnetic tunnel junctions (MTJs) using Co₂FeSi_0.5Al_0.5 (CFSA(0.5)) Heusler alloy electrodes. The 390% TMR corresponds to 0.81 spin polarization for CFSA(0.5) at 5 K. We also investigated the crystalline structure and local structure around Co atoms by x-ray diffraction (XRD) and nuclear magnetic resonance (NMR) analyses, respectively, for CFSA films sputtered on a Cr-buffered MgO (001) substrate followed by post-annealing at various temperatures in an ultrahigh vacuum. The disordered structures in CFSA films were clarified by NMR measurements and the relationship between TMR and the disordered structure was discussed. We clarified that the TMR of the MTJs with CFSA(0.5) electrodes depends on the structure, and is significantly higher for L2₁ than B2 in the crystalline structure. The second part of this paper is devoted to a SFD using a ferromagnetic barrier. The Co ferrite is investigated as a ferromagnetic barrier because of its high Curie temperature and high resistivity. We demonstrate the strong spin filtering effect through an ultrathin insulating ferrimagnetic Co-ferrite barrier at a low temperature. The barrier was prepared by the surface plasma oxidization of a CoFe₂ film deposited on a MgO (001) single crystal substrate, wherein the spinel structure of CoFe₂O₄ (CFO) and an epitaxial relationship of MgO(001)[100]/CoFe₂ (001)]110]/CFO(001)[100] were induced. A SFD consisting of CoFe₂ /CFO/Ta on a MgO (001) substrate exhibits the inverse TMR of - 124% at 10 K when the configuration of the magnetizations of CFO and CoFe₂ changes from parallel to antiparallel. The inverse TMR suggests the negative spin polarization of CFO, which is consistent with the band structure of CFO obtained by first principle calculation. The - 124% TMR corresponds to the spin filtering efficiency of 77% by the CFO barrier.