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131.
Madihian M. Bak E. Yoshida H. Hirabayashi H. Imai K. Kinoshita Y. Yamazaki T. Desclos L. 《Solid-State Circuits, IEEE Journal of》1997,32(4):521-525
This paper concerns the design consideration, fabrication process, and performance results for an ultra-broadband, low-voltage, low-power, BiCMOS-based transceiver chip for cellular-satellite-LAN wireless communication networks. The transceiver chip incorporates an RF amplifier, a Gilbert down-mixer, and an IF amplifier in the receive path, and an IF amplifier, a Gilbert up-mixer, and an RF amplifier in the transmit path. For an RF frequency in the 1-10 GHz band and an IF frequency in the 100-1000 MHz band, the developed transceiver chip consumes less than 60 mW at 2 V, to yield a downconversion gain of 40 dB at 1 GHz and 10 dB at 10 GHz and an upconversion gain of 42 dB at 1 GHz and 11 dB at 10 GHz. To avoid possible start-up problems caused during “stand-by” to “enable” mode transition, a simple switching technique is employed for enabling either the receive or the transmit path, by changing the value of a reference voltage applied to both the down- and the up-mixers. While the developed transceiver chip exhibits the best performance for a dc supply voltage of 2 V, it shows a graceful degradation for a ±0.15 V voltage deviation. The transceiver's chip size is 1.04 mm×1.04 mm 相似文献
132.
133.
MAG (metal active gas) arc welding is an important and widely used welding process that allows welding to proceed at high efficiency through appropriate selection of operating parameters, such as the welding current, welding speed, shielding gas composition, etc. Experimental determination of optimum operating parameters, however, is costly and time-consuming, although welding process simulations based on mathematical models are expected to be able to solve the problem of time and costs. 相似文献
134.
Xiang Cheng Zhigang Wang Kazuo Nakamoto Kazuo Yamazaki 《The International Journal of Advanced Manufacturing Technology》2011,53(5-8):523-533
Many researches have studied the micro tools either by simulations or experiments showing that the micro tools play very important roles in micro/nano machining, and micro tool geometries have a direct impact on the final machining quality. Commercially available micro milling tools are usually simply made from downsizing of macro milling tools, which may not be able to be accurately fabricated. Custom micro milling tools have been created by some researchers, but no design criteria for micro milling tools have been introduced. The above factors constrain the development of effective micro milling tools and consequently constrain the researches on micro/nano milling. Based on former researcher??s work, this paper tries to introduce the design criteria for the custom micro tooling. Firstly, the extent typical micro milling tools are studied, and their drawback/limitations are summarized. Secondly, experimental evaluations of the key drawback/limitations are processed. Thirdly, the design criteria for custom micro milling tools are proposed, and corresponding design process is introduced. Then, a new micro hexagonal end mill has been designed based on these criteria. Finally, a polycrystalline diamond micro hexagonal end mill with a diameter of 0.5?mm was fabricated by wire electrical discharge machining, and the evaluation experiments for the hexagonal end mill have been processed on a nano milling center. Experimental results show the newly designed hexagonal end mill can achieve submicron level surface roughness and has simultaneously high-accuracy side and bottom machining capabilities. 相似文献
135.
Ryoichi Furushima Yohtaro Matsuo Tadashi Shiota Kouichi Yasuda 《Journal of Nondestructive Evaluation》2011,30(1):29-40
Changes in amplitude and phase shifts in plane elastic waves were theoretically estimated when they propagated through an
elastic body containing cylindrical inclusions. Based on the integral equation suggested by Lavrov et al., these changes were
calculated in the case when only one cylindrical inclusion was located in the body and the propagating waves have a single
frequency. These calculations were expanded to more practical case when multiple cylindrical inclusions aligned in the body
and the waves have some frequency band. The changes in amplitude and phase shifts calculated were associated to the changes
in apparent sonic velocity and attenuation coefficient due to a structural change in the material. This theoretical approach
contributes to a quantitative damage evaluation based upon structural changes in various materials by measuring the acoustical
parameters such as apparent sonic velocity and attenuation coefficient. 相似文献
136.
Akira Miyazaki Takayuki Yamazaki Taikan Suehara Toshio Namba Shoji Asai Tomio Kobayashi Haruo Saito Toshitaka Idehara Isamu Ogawa Yoshinori Tatematsu 《Journal of Infrared, Millimeter and Terahertz Waves》2014,35(1):91-100
Positronium is an ideal system for research on Quantum Electrodynamics (QED), especially in a bound state. A discrepancy of 3.9 standard deviations has been found between the measured hyperfine structure (Ps-HFS) and the QED predictions. This may be due to the contribution of unknown new physics or common systematic effects in previous measurements, in all of which the Zeeman effect was used. We propose a new method to directly measure the Ps-HFS using a high power gyrotron. We compare two resonators which have been developed to supply sufficient power to drive the direct transition, a Fabry-Pérot resonator and a ring resonator with a diffraction grating. We plan to perform first direct measurement of Ps-HFS within the next six months. 相似文献
137.
138.
K Yamazaki K Sato K Shizume Y Kanaji Y Ito T Obara T Nakagawa T Koizumi R Nishimura 《Canadian Metallurgical Quarterly》1995,80(2):473-479
Using a highly sensitive bioassay for TSH, in which human thyroid follicles incorporate 125I and release de novo synthesized thyroid hormone into the culture medium, the thyrotropic activities of various hCG preparations were studied. Under the culture conditions employed, bovine TSH (bTSH) was approximately 6- to 9-fold more active than human TSH (hTSH). Highly purified hCG prepared from urine of normal pregnant women (CR 127) had only a trivial thyrotropic activity equipotent to 0.00022 microU bTSH/U hCG or 0.0013 microU hTSH/U hCG (19.7 microU hTSH/mg hCG). Hybrid hCG (AB1ER) also elicited low thyrotropic activity (14.0 microU hTSH/mg), whereas crude hCG had moderate thyrotropic activity (0.041 hTSH microU/U hCG or 127 microU/mg protein). Deglycosylated hCG, a very weak LH/hCG receptor agonist, was the most potent agonist in thyroid follicles (588 microU hTSH/mg protein). hCGs purified from urine of patients with trophoblastic tumors had greater TSH-like activity (37-84 microU hTSH/mg protein) than purified hCG. Asialo-hCG purified from a patient with choriocarcinoma had very potent TSH-like activity (468 microU hTSH/mg). Submaximal doses of bTSH and hCG variants produced additive stimulation of thyroid function. Furthermore, the thyrotropic effect of hCG was inhibited by anti-TSH receptor antibody obtained from patients with myxedema. These in vitro findings suggest that although hCG is reported to exert potent cAMP-stimulating activity on rat thyroid-like cells (FRTL-5) and Chinese hamster ovary cells transfected with hTSH receptor complementary DNA (0.092-0.72 microU hTSH/U hCG), the thyrotropic activity induced by authentic hCG in human thyroid follicles is too weak to cause hyperthyroidism in normal pregnancy. However, hCG produced by some trophoblastic tumors, particularly asialo-hCG, has potent thyrotropic activity sufficient to cause clinically overt hyperthyroidism when produced excessively. 相似文献
139.
K Kubo Y Yamazaki T Masubuchi A Takamizawa H Yamamoto T Koizumi K Fujimoto Y Matsuzawa T Honda M Hasegawa S Sone 《Canadian Metallurgical Quarterly》1998,158(3):979-984
To clarify the structure and function of the airways in Mycobacterium avium-intracellulare (MAI) infection, we performed pulmonary function tests and high-resolution computed tomography (HRCT) of the thorax in female patients 61 +/- 9 yr of age (n = 12) with pulmonary MAI infection without predisposing lung disease and compared their data with those of normal female volunteers 54 +/- 8 yr of age (n = 9). We calculated the E/I ratio, i.e., the average ratio of HRCT number at full expiration to that at full inspiration, as an index for the evaluation of air trapping distal to the small airways. Patients showed significant increases in residual volume and slope of phase III (DeltaN2) of the single-breath nitrogen test, and significant decreases in flow at 50 and 25% of FVC, suggesting hyperinflation and obstruction of the small airways. HRCT of patients revealed the small nodules and ectasis of bronchioles and small bronchi located mainly in segments (S) S2, S3, S4, and S5. The E/I ratio was significantly elevated in patients, and especially higher in the upper lung field than in the lower lung field, suggesting air trapping distal to the small airways. The difference of E/I ratio between the upper and lower field is probably related to the segmental distribution of CT abnormalities. These findings suggest that MAI infection can lead to air trapping distal to the small airways. 相似文献
140.
S Yamashita H Yamazaki T Kato T Yokota N Matsumoto S Matsukura 《Canadian Metallurgical Quarterly》1996,35(3):215-218
The first human infection caused by Ascotricha chartarum of the maxillary sinus is described. The patient, a 35-year-old woman, developed a hard bony swelling on the right cheek. Her maxillary X-ray showed complete opacity of the right maxillary antrum with a shadow of erosion. C.T. scan revealed a radio opaque mass having vacuolated appearance in the antrum. The debris removed from the antrum contained phaeoid fungal elements. At places, softening of the bone was observed. The mucoperiosteum exhibited acute inflammatory reaction and invasion by the pathogen. The pale brown to subhyaline fungal elements in biopsy tissue grew Ascotricha chartarum, a phaeoid ascomycetous fungus in culture. The patient had a smooth recovery when treated with betadine lavage and itraconazole after surgical intervention. 相似文献