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排序方式: 共有183条查询结果,搜索用时 15 毫秒
1.
Kameyama H. Miyajima T. Zhi Ding 《IEEE transactions on circuits and systems. I, Regular papers》2008,55(3):851-860
In multicarrier systems, when the order of a channel impulse response is larger than the length of the cyclic prefix (CP), there is a significant performance degradation due to interblock interference (IBI). This paper proposes a blind-channel shortening method in which the equalizer parameter vector is formed by the noise subspace of the received signal correlation matrix so that the output power is maximized. The proposed method can not only shorten the effective channel impulse response to within the CP length but also maximize the output signal-to-interference-and-noise ratio while eliminating the IBI. We point out that the performance depends on the choice of a decision delay and propose a simple method for determining the appropriate delay. We propose both a batch algorithm and an adaptive algorithm and show by simulation that they are superior to the conventional algorithms. 相似文献
2.
A. Bozbey S. Miyajima T. Ortlepp A. Fujimaki 《Journal of Superconductivity and Novel Magnetism》2011,24(1-2):1065-1069
In this study, we report on our simulation and experimental results for quasi-one junction SQUIDs (QOS) comparator targeted to be used in the front-end of the detector read-out circuits. The QOS is used as a 1-bit quantizer in the front-end of the read-out circuit. Their performance and reliability is very much depending on the circuit parameters of the QOSs. The main design parameters are the threshold level, gray zone width, and the chip-to-chip reproducibility over different fabrication batches. For some special applications, such as detector readout, the overall power consumption needs to be sufficient small. We measured threshold and gray zone counting each individual switching event for various bias and input current values and for different QOS designs. In addition, circuit simulations including thermal noise are used to explain the observed circuit behavior and to optimize design parameters. 相似文献
3.
Okuyama H. Miyajima T. Morinaga Y. Hiei F. Ozawa M. Akimoto K. 《Electronics letters》1992,28(19):1798-1799
The continuous wave operation of an ZnSe/ZnMgSSe laser diode was achieved for the first time at 77 K. Blue stimulated emission was observed at a wavelength of 447 nm and the threshold current density was 225 A/cm/sup 2/.<> 相似文献
4.
Kojima T. Miyajima M. Akaboshi F. Yogo T. Ishimoto S. Okuda A. 《Semiconductor Manufacturing, IEEE Transactions on》2000,13(3):293-299
We have developed a chemical mechanical polishing (CMP) process monitor which uses polishing vibration. The monitor enables us to accurately detect the polishing end point in copper (Cu) polishing even when the process conditions such as initial film thickness, slurry flow and polishing rate are changed and when polishing multilayer film. Furthermore, the monitor is not only applicable to Cu polishing but also to planarizing polishing of an inter-level dielectric layer. The monitor can be also used to control the processes and the equipment because of its capability to detect abnormalities in the polishing conditions 相似文献
5.
Komukai T. Yamamoto T. Sugawa T. Miyajima Y. 《Quantum Electronics, IEEE Journal of》1995,31(11):1880-1889
A 1.064-μm band upconversion pumped Tm3+-doped fluoride fiber amplifier and a laser both operating at 1.47 μm are investigated in detail. The two devices are based on the 3F 4→3H4 transition in a trivalent thulium ion, which is a self-terminating system. When pumped at 1.064 μm, the amplifier has a gain of over 10 dB from 1.44 to 1.51 μm and a low-noise characteristic. Also, the fiber laser generates a high-output power of over 100 mW with a slope efficiency of 59% at around 1.47 μm. These levels of performance will be important for optical communication systems 相似文献
6.
The amplification characteristics at around 1.5 μm of a 0.9-m-long, 1000-p.p.m Er3+-doped single-mode fluoride fiber are discussed. By using 1.48-μm laser diodes with 55-mW launched output as a pump source, a gain of 1.75 dB was obtained at 1.530 μm. A broad bandwidth of 40 nm was obtained, which may be suitable for wavelength-division multiplexing (WDM) system use 相似文献
7.
A highly efficient and tunable Nd/sup 3+/ doped fluoride fibre laser operating in the 1.3 mu m band pumped at 0.8 mu m is demonstrated. The pump laser is a titanium sapphire laser and the tuning element is a dielectric multicoated bandpass filter inserted in the cavity. The oscillation wavelength was successfully tuned from 1.315 to 1.348 mu m for the first time.<> 相似文献
8.
Shinya Kato Yasuyoshi Kurokawa Shinsuke Miyajima Yuya Watanabe Akira Yamada Yoshimi Ohta Yusuke Niwa Masaki Hirota 《Nanoscale research letters》2013,8(1):361
To achieve a high-efficiency silicon nanowire (SiNW) solar cell, surface passivation technique is very important because a SiNW array has a large surface area. We successfully prepared by atomic layer deposition (ALD) high-quality aluminum oxide (Al2O3) film for passivation on the whole surface of the SiNW arrays. The minority carrier lifetime of the Al2O3-depositedSiNW arrays with bulk silicon substrate was improved to 27 μs at the optimum annealing condition. To remove the effect of bulk silicon, the effective diffusion length of minority carriers in the SiNW array was estimated by simple equations and a device simulator. As a result, it was revealed that the effective diffusion length in the SiNW arrays increased from 3.25 to 13.5 μm by depositing Al2O3 and post-annealing at 400°C. This improvement of the diffusion length is very important for application to solar cells, and Al2O3 deposited by ALD is a promising passivation material for a structure with high aspect ratio such as SiNW arrays. 相似文献
9.
Wataru Kanematsu Tatsuya Miyajima Mutsuo Sando 《Journal of the American Ceramic Society》2001,84(10):2427-2429
A visualizing technique for indentation damage of ceramics was developed. Plasma etching was used to enhance the view of cracks and the subsurface microcracking crush zone following Knoop indentation of hot pressed Si3 N4 . The microcracking zone was readily identified from the surface view of the indented surface as a grain-falling-off region (GFOR), defined as a region in which grains were removed by preferential etching using CF4 gas, followed by ultrasonic cleaning. A fissure-like opening corresponding to the indentation cracks was also observed. It is inferred that the formation of the GFOR region and the fissure-like opening were caused by the etching/cleaning treatment. Meanwhile, the etching on a section which included diagonals of the impression provided a section view of the microcracking zone. 相似文献
10.
Numerical Evaluation of Toughening by Crack-Face Grain Interlocking in Self-Reinforced Ceramics 总被引:1,自引:0,他引:1
Serguei Kovalev Tatsuya Miyajima Yukihiko Yamauchi Mototsugu Sakai 《Journal of the American Ceramic Society》2000,83(4):817-824
Crack bridging associated with the pull-out process of interlocking grains in self-reinforced ceramic materials is studied through a micromechanical simulation. The pullout of a single inclined grain is modeled via the numerical solution of a general contact problem. The bridging-force versus crack-opening-distance curve indicates a nonlinear, springlike response for the pullout of interlocking grains. The sliding friction along the debonded interface, induced by highly localized contact stresses, dominates the total bridging force. The bridging force increases with grain inclination until eventual bridge failure. The pullout of misaligned grains mainly affects short-crack toughening, with a rising R -curve, whereas aligned grains contribute to long-crack toughening. The residual stresses of the thermal expansion anisotropy play a minor role in the pull-out process of grain interlocking and the resultant toughening. The proposed mechanism is operative in both single-phase and composite ceramics in which pullout of elongated grains/reinforcements occurs. 相似文献