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961.
We have examined the applicability of this simple and effective test to polymer systems widely used in the medical industry. First, it was found that not every polymer examined exhibited a distinct onset of autocatalytic oxidation detectable by DSC. However, for cases where distinct onsets are found, powerful insights can be obtained. These included activation energy of the degradation, thermal oxidative shelf life prediction, and correlation, with product performances. Actual examples are presented to illustrate the utility of the test. 相似文献
962.
Kim S. Jeong S. Lee Y.T. Kim D.-H. Lim J.-S. Seo K.-S. Nam S. 《Electronics letters》2002,38(13):622-623
A new ultra-wideband, low-loss and small-size coplanar waveguide (CPW) to coplanar strip (CPS) transition which can be used from DC to 110 GHz is presented. The proposed transition connects CPW with CPS by the reformed air-bridge. Two ground planes of CPW are tied at their ends by a line and the centre of the line is connected to the ground strip of CPS by another line. Owing to the symmetry of the proposed structure, the currents of two ground planes of CPW are combined with the same phase and transferred to the ground strip of CPS. With height of 3 μm, the signal line of CPW passes over two connecting lines and is connected to the signal strip of CPS. For the back-to-back transition structure, insertion loss <1 dB and return loss >15 dB are obtained from 0.5 to 110 GHz 相似文献
963.
T. M. Holden J. W. L. Pang R. A. Holt 《Metallurgical and Materials Transactions A》2002,33(3):749-755
The development of the understanding of the intergranular stresses in ZIRCALOY-2 is reviewed. Neutron diffraction measurements
of the intergranular strains were made on rod-textured material and highly textured plate. The elastoplastic self-consistent
(EPSC) model provides a sound theoretical foundation for our understanding of the behavior. The strain response of ZIRCALOY-2
to applied tensile stress is well described for two very different textures with the same slip and hardening parameters. It
is almost certain that tensile twinning is the explanation for the response to compressive stress and rolling that is, as
yet, incompletely understood.
This article is based on a presentation made in the symposium entitled “Defect Properties and Mechanical Behavior of HCP Metals
and Alloys” at the TMS Annual Meeting, February 11–15, 2001, in New Orleans, Louisiana, under the auspices of the following
ASM committees: Materials Science Critical Technology Sector, Structural Materials Division, Electronic, Magnetic & Photonic
Materials Division, Chemistry & Physics of Materials Committee, Joint Nuclear Materials Committee, and Titanium Committee. 相似文献
964.
Courteville A. Gharbi T. Cornu J.Y. 《IEEE transactions on bio-medical engineering》1998,45(2):145-150
A high-sensitivity human muscle-vibration measurement (MMG) sensor adapted to clinical use is presented. The muscle vibration phenomenon is modeled and investigated to optimize the measurement technique. The sensor uses an acoustic impedance adaptation technique to convert the skin surface vibration in terms of acoustic pressure, which is sensed by a microphone. The device is calibrated and gives the real amplitude of the vibration. It is also well fitted to measure other physiological vibrations in the 2 Hz-1 kHz range 相似文献
965.
This paper describes a new write/erase method for flash memory to improve the read disturb characteristics by means of drastically reducing the stress leakage current in the tunnel oxide. This new write/erase operation method is based on the newly discovered three decay characteristics of the stress leakage current. The features of the proposed write/erase method are as follows: 1) the polarity of the additional pulse after applying write/erase pulse is the same as that of the control gate voltage in the read operation; 2) the voltage of the additional pulse is higher than that of a control gate in a read operation, and lower than that of a control gate in a write operation; and 3) an additional pulse is applied to the control gate just after a completion of the write/erase operation. With the proposed write/erase method, the degradation of the read disturb life time after 106 write/erase cycles can be drastically reduced by 50% in comparison with the conventional bipolarity write/erase method used for NAND type flash memory. Furthermore, the degradation can he drastically reduced by 90% in comparison with the conventional unipolarity write/erase method fur NOR-, AND-, and DINOR-type flash memory. This proposed write/erase operation method has superior potential for applications to 256 Mb flash memories and beyond 相似文献
966.
The authors present an adaptive space-time reduced-length minimum mean-squared error (MMSE) receiver to suppress co-channel interference in the near-far environment for an asynchronous direct-sequence code-division multiple-access (DS/CDMA) system. Simulation results show that better bit-error rate and faster and more stable convergence are achieved over the existing full- and reduced-length MMSE receivers 相似文献
967.
Y. Itoh Y. Mitsunaka K. Sakamoto T. Nagashima 《Journal of Infrared, Millimeter and Terahertz Waves》1992,13(9):1353-1359
An experiment was carried out for transforming the 120 GHz-TE12.2 whispering-gallery mode (WGM) into a circularly polarized hollow radiation beam. A hollow beam was formed by reflecting the WGM, which was radiated from a 16 mm radius circular waveguide cut, with an annular mirror having suitable local normal vectors. The experimentally observed field intensity profiles of the reflected wave were in good agreement with calculated results. 相似文献
968.
969.
A potential barrier model along the grain boundaries in ultrathin tin dioxide (SnO2) gas sensors is presented. It is assumed that the negatively charged oxygens are adsorbed only on the grain boundaries. The
potential barrier depth is expressed as functions of grain size, donor concentration and surface coverage of adsorbed oxygen
ions at the boundaries. A direct consequence is that the conduction electrons are effectively confined in a grain when the
film thickness becomes smaller than a critical value. This indicates a drastic increase in resistivity with decreasing film
thickness in air, and thus an occurrence of an extremely high gas sensitivity. 相似文献
970.
Design of artificial satellites for communication, remote sensing and scientific investigations follows, at present, a fixed
pattern based on existing and proven technologies and the requirements of payload or experiment within the constraints of
weight, volume and power available. The advances in optoelectronic components and systems have opened up a new dimension in
designing satellites of the future, incorporating new technologies. This paper deals with general satellite design concepts
based on optoelectronic systems wherever applicable. 相似文献