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排序方式: 共有1384条查询结果,搜索用时 15 毫秒
81.
Mode analysis of spreading of partially coherent beams propagating through atmospheric turbulence 总被引:11,自引:0,他引:11
Shirai T Dogariu A Wolf E 《Journal of the Optical Society of America. A, Optics, image science, and vision》2003,20(6):1094-1102
The spreading of partially coherent beams propagating through atmospheric turbulence is studied by use of the coherent-mode representation of the beams. Specifically, we consider partially coherent Gaussian Schell-model beams entering the atmosphere, and we examine the spreading of each coherent mode, represented by a Hermite-Gaussian function, on propagation. We find that in atmospheric turbulence the relative spreading of higher-order modes is smaller than that of lower-order modes, whereas the relative spreading of all order modes is the same as in free space. This modal behavior successfully explains why under certain circumstances partially coherent beams are less affected by atmospheric turbulence than are fully spatially coherent laser beams. 相似文献
82.
Xiaoyuan He Tomotaka Ogura Akihiro Satou Osamu Hasegawa 《IEEE transactions on systems, man, and cybernetics. Part B, Cybernetics》2007,37(5):1357-1372
We present a new approach for online incremental word acquisition and grammar learning by humanoid robots. Using no data set provided in advance, the proposed system grounds language in a physical context, as mediated by its perceptual capacities. It is carried out using show-and-tell procedures, interacting with its human partner. Moreover, this procedure is open-ended for new words and multiword utterances. These facilities are supported by a self-organizing incremental neural network, which can execute online unsupervised classification and topology learning. Embodied with a mental imagery, the system also learns by both top-down and bottom-up processes, which are the syntactic structures that are contained in utterances. Thereby, it performs simple grammar learning. Under such a multimodal scheme, the robot is able to describe online a given physical context (both static and dynamic) through natural language expressions. It can also perform actions through verbal interactions with its human partner. 相似文献
83.
Eiji Shirai 《Circuits and Systems II: Express Briefs, IEEE Transactions on》2007,54(2):166-170
This brief describes a design technique for multistage preamplifiers of the type commonly used in high-performance comparators. Following the examination of multistage preamplifier responses in both the spectral and time domains, and a consideration 1/f noise attenuation in topologies employing offset storage capacitors, a procedure for optimizing both the number of stages and the offset storage capacitance is presented. As a demonstration vehicle, a comparator with a 13-Msample/s conversion rate and 200-muV minimum input resolution is designed for realization in a 0.4-mum CMOS technology under the constraint of a power dissipation of 250 muW when operating from a 2.5-V supply. In this design, the effective input signal is 33 muV for the minimum input resolution of 200 muV due to signal corruption from circuit noise and residual error from incomplete settling 相似文献
84.
Okamura M. Kimura K. Shirai S. Yamauchi N. 《Electron Devices, IEEE Transactions on》1994,41(2):180-185
A light-transmitting two-dimensional photodetector array (32×32 cells) using amorphous silicon (a-Si) pin photodiodes and polysilicon (poly-Si) thin film transistors (TFT's) integrated on a transparent substrate has been developed for use in a free-space optical switching network. The fabrication and the characteristics of the photodetector array are discussed. With driving circuits and sensing amplifiers, this photodetector array shows a minimum detectable power of -25 dBm and an insertion loss of 0.4 dB for an incident optical beam with a diameter of 550 μm. By monitoring the positions and the states of input optical beams, this photodetector array can be used to control the optical paths in photonic switching systems, such as a 1024-input-port optical concentrator 相似文献
85.
Detection of genetically modified organisms in foreign-made processed foods containing corn and potato 总被引:1,自引:0,他引:1
Monma K Araki R Sagi N Satoh M Ichikawa H Satoh K Tobe T Kamata K Hino A Saito K 《Shokuhin eiseigaku zasshi. Journal of the Food Hygienic Society of Japan》2005,46(3):79-85
Investigations of the validity of labeling regarding genetically modified (GM) products were conducted using polymerase chain reaction (PCR) methods for foreign-made processed foods made from corn and potato purchased in the Tokyo area and in the USA. Several kinds of GM crops were detected in 12 of 32 samples of processed corn samples. More than two GM events for which safety reviews have been completed in Japan were simultaneously detected in 10 samples. GM events MON810 and Bt11 were most frequently detected in the samples by qualitative PCR methods. MON810 was detected in 11 of the 12 samples, and Bt11 was detected in 6 of the 12 samples. In addition, Roundup Ready soy was detected in one of the 12 samples. On the other hand, CBH351, for which the safety assessment was withdrawn in Japan, was not detected in any of the 12 samples. A trial quantitative analysis was performed on six of the GM maize qualitatively positive samples. The estimated amounts of GM maize in these samples ranged from 0.2 to 2.8%, except for one sample, which contained 24.1%. For this sample, the total amount found by event-specific quantitative analysis was 23.8%. Additionally, Roundup Ready soy was detected in one sample of 21 potato-processed foods, although GM potatoes were not detected in any sample. 相似文献
86.
Tuneo Suzuki Hirofusa Shirai Nobumasa Hojo 《Journal of Inorganic and Organometallic Polymers and Materials》1994,4(3):251-260
The kinetics of the metal exchange reaction between Cu(II)-poly(vinyl alcohol) [Cu(II)-PVA] and Zn(II)-ethylenediamine-N,N,N′,N′-tetraacetic acid [Zn(II)-EDTA] has been studied by mixing both solutions in a spectrophotometer at pH 10.0 to 11.0, ionic strength μ=0.10(KNO3), and 15 to 35°C. The reaction is initiated by the formation of unstable Cu(II)-H-PVA through attack of H+ ion on the Cu(II)-PVA complex, and both reactions, ligand exchange and metal exchange, proceed simultaneously. The metal exchange step may be rate determining. The rate equation and rate constants of this reaction were determined as follows: ?d[Cu(II)-PVA]/dt=k 0(H)[PVA?][Cu(II)-PVA] [Zn(II)-EDTA], wherek 0(H)=k 1+(k′2+k′3)[H+],k 1=5.98±1.64M ?1 s?1, andk 2+k 3=k′2 K Cu(II)-H-PVA ?H +k′3 K Zn(II)-EDTA H =(5.91±0.89)×107 M ?2 s?1. 相似文献
87.
S Kozlowski M Corr M Shirai LF Boyd CD Pendleton JA Berzofsky DH Margulies 《Canadian Metallurgical Quarterly》1993,151(8):4033-4044
T cell stimulation by certain class I-restricted antigenic peptides, such as the HIV 1 gp160-derived peptide, P18, requires peptide processing by angiotensin-1 converting enzyme (ACE) in FCS. We observed that longer versions of P18 and the murine cytomegalovirus pp89-derived core peptide, pMCMV, which could stimulate T cell hybridomas in FCS, were not as sensitive to the ACE inhibitor captopril as P18. Using cell-free soluble murine class I MHC molecules and protease inhibitors, we found that there are pathways of differing efficiency that use enzymes other than ACE for the proteolytic processing of peptides in serum. The kinetics of the generation of T cell stimulatory activity among P18 variant peptides in serum differed with peptide length, and with the nature of amino and COOH-terminal extensions. Such processing occurs in human plasma as well as in FCS. The understanding of this processing, its kinetics, and its inhibitors can lead to better design of peptide-based therapies, including vaccines. 相似文献
88.
Takuro Tomita Ayahito Uetake Tsutomu Asahina Kentaro Kayanuma Akihiro Murayama Yasuo Oka 《Journal of Superconductivity and Novel Magnetism》2005,18(3):405-410
Spin injection processes in the double quantum dots of ZnSe-based diluted magnetic semiconductors are discussed. Double quantum
dots are fabricated from ZnSe-based double quantum wells by electron beam lithography and wet etching. In these samples, the
photo-excited carriers in the magnetic dots are injected into the non-magnetic dots. The circular polarization degrees of
photoluminescence from the non-magnetic dots are measured by micro-photoluminescence measurement system under the magnetic
field up to 5 T. The maximum spin polarization degrees of injected carriers determined from our experiment are 10% for double
quantum wells and 15% for double quantum dots. The spin injection efficiency was estimated both from the observed circular
polarization degree and the diffusion length of carriers. We concluded that the spin injection efficiency is increased in
the double quantum dots. 相似文献
89.
Dariusz Kata Kenshiro Shirai Manshi Ohyanagi Zuhair A. Munir 《Journal of the American Ceramic Society》2001,84(4):726-732
The synthesis of solid solutions of AlN–SiC was investigated through the combustion reaction between Si3 N4 , aluminum, and carbon powders and nitrogen gas at pressures ranging from 0.1 to 6.0 MPa. The combustion reaction was initiated locally and then the wave front propagated spontaneously, passing through the cylindrical bed containing the loose powder. In the presence of Si3 N4 as a reactant, it was feasible to synthesize solid solutions at an ambient pressure (0.1 MPa). The relationship between nitrogen pressure and full-width at half-maximum of the (110) peak of the product showed that lower pressures produced more-homogeneous solid solutions. Some aspects of formation of the AlN–SiC solid solutions were discussed with special emphasis on the influence of nitrogen pressure and reactant stoichiometry. 相似文献
90.
Akihiro Ishimi Kozo Katsuyama Koji Maeda Tsuyoshi Nagamine Takeo Asaga Hirotaka Furuya 《Journal of Nuclear Science and Technology》2013,50(12):1144-1155
The X-ray CT technology previously developed by JAEA was upgraded. The shape of the X-ray source beam was changed from a circular shape to an elliptical one and the collimator slit width was decreased from 0.3 to 0.1 mm. The X-ray detector was improved by changing a CdWO4 scintillator to a highly sensitive silicon semiconductor detector. The analysis code of X-ray CT image was revised with respect to the number of points by using two kinds of experimental results and taking into account the effects of crack existence and deviation of the central void position from the radial center of a fuel pellet. As a result, high resolution X-ray CT images could be obtained on the transverse cross section of irradiated fuel assemblies. The error of the dimensional measurement was improved from ±0.1 to ±0.03 mm by upgrading the instrument and revising the analysis code of X-ray CT image. The discriminating accuracy of density difference could be increased, and the low density region (undisturbed region) and high density region (equi-axial and columnar regions) in the X-ray CT image on the cross section of irradiated fuel could be discriminated from each other. The reliability of fuel performance analysis improves because a large number of PIE data can be collected, compared with the conventional destructive PIE. 相似文献