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961.
Shin S.-C. Ming-Da Tsai Ren-Chieh Liu Lin K.-Y. Huei Wang 《Microwave and Wireless Components Letters, IEEE》2005,15(7):448-450
A 24-GHz low-noise amplifier (LNA) was designed and fabricated in a standard 0.18-/spl mu/m CMOS technology. The LNA chip achieves a peak gain of 13.1 dB at 24 GHz and a minimum noise figure of 3.9 dB at 24.3 GHz. The supply voltage and supply current are 1 V and 14 mA, respectively. To the author's knowledge, this LNA demonstrates the lowest noise figure among the reported LNAs in standard CMOS processes above 20 GHz. 相似文献
962.
Three sorbents were compared in order to determine their potential for oil spill cleanup. Polypropylene nonwoven web, rice hull, and bagasse with two different particle sizes were evaluated in terms of oil sorption capacities and oil recovery efficiencies. Polypropylene can sorb almost 7 to 9 times its weight from different oils. Bagasse, 18 to 45 mesh size, follows polypropylene as the second sorbent in oil spill cleanup. Bagasse, 14 to 18 mesh size, and rice hull have comparable oil sorption capacities, which are lower than those of the two former sorbents. It was found that oil viscosity plays an important role in oil sorption by sorbents. All adsorbents used in this work could remove the oil from the surface of the water preferentially. 相似文献
963.
Different NMR techniques were combined to obtain the structure and velocity information for a systematic investigation of fixed beds with low aspect ratio (tube diameter to particle diamter, dt/dp) in the range 1.4 to 32. The structure of the void space was determined for a variety of packed beds of glass beads or regular and irregular porous pellets by magnetic resonance imaging (MRI). Based on the images the radial distribution of the voids within the bed was obtained. Ordering effects were found even for non‐spherical and polydisperse particles, and a maximum of the fluid density near the tube wall was confirmed for all pellet geometries and sizes. By combining MRI with velocity encoding, velocity profiles and distributions of flow velocity components of a single fluid phase through packed beds have been acquired. The radial velocity distribution follows an oscillatory pattern which largely reflects the ordering of the particles, which can be accessed from the density distribution of the interparticle fluid. Maximum velocities of up to four times the average value were found to occur near the tube wall. This wall effect was observed for all but the smallest particles, where the aspect ratio was dt/dp = 32. Moreover, a visualisation of flow pattern in the presence of packed particles was achieved by using a tagging technique, and the stationary flow field could be identified for an experimental time of several hours. 相似文献
964.
The charge storage characteristics of P-channel Ge/Si hetero-nanocrystal based MOSFET memory has been investigated and a logical array has been constructed using this memory cell. In the case of the thickness of tunneling oxide T_ox=2nm and the dimensions of Si- and Ge-nanocrystal D_Si=D_Ge=5nm, the retention time of this device can reach ten years(~1×10~8s) while the programming and erasing time achieve the orders of microsecond and millisecond at the control gate voltage |V_g|=3V with respect to N-wells, respectively. Therefore, this novel device, as an excellent nonvolatile memory operating at room temperature, is desired to obtain application in future VLSI. 相似文献
965.
966.
967.
Yen-Kang Liu Pei-Lum Tso 《The International Journal of Advanced Manufacturing Technology》2003,22(5-6):396-400
Grinding is the most suitable process for manufacturing good quality diamond tools. In this paper, diamond wheels have been studied. From the grinding of polycrystalline diamond (PCD) insets, the effects of certain factors such as the bonding material, the grit size and structure of a diamond wheel have been investigated. It is concluded that vitrified bond diamond wheels are the most suitable for grinding PCDs and the recommended grit size is mesh number 1000, which can get a good surface quality within an appropriate time. The wheel structure is another important factor. Rougher wheels (mesh #800, #1000) with the softer grade scale P yield a higher material removal rate (MRR) than scale Q. However, a finer wheel (mesh #1200) needs a tougher structure to promote its grinding ability and to have a higher MRR. 相似文献
968.
V. Ya. Basevich A. A. Belyaev V. Brandshteter M. G. Neigauz R. Tashl S. M. Frolov 《Combustion, Explosion, and Shock Waves》1994,30(6):737-745
A detailed kinetic mechanism is proposed for the oxidation of iso-octane, n-heptane, and mixtures of them in air (number of particles 43, number of reactions 284), which satisfactorily describes the distinctive features of low-temperature and high-temperature oxidation at an initial temperature of 1200 K, pressure of 15–40 absolute atmospheres or higher, and a fuel excess ratio of 0.5–2. The abbreviated mechanisms obtained to describe the auto-ignition of fuel with an octane number of 90 involve 27 particles (38 reactions) and 18 particles (22 reactions).N. N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, Moscow, 117977. Translated from Fizika Goreniya i Vzyrva, Vol. 30, No. 6, pp. 15–25, November–December, 1994. 相似文献
969.
De Jun Mu Guan-Zhong Dai Liu K.J.R. Yao K. 《Signal Processing, IEEE Transactions on》1995,43(2):555-556
Comments that the paper by Liu and Yao (see ibid., vol.40, no.1, p.190, 1992) presented an efficient algorithm for spectral decomposition, but the parallel algorithm and architecture for the Hessenberg reduction has a problem. The matrix obtained from the unitary similarity transformation is not necessarily a Hessenberg matrix. The authors reply that the Hessenberg reduction described is not in the Hessenberg form. Only the first column is in its proper form. There are many ways to overcome such a problem. One simple way is to use the multiphase rectangular systolic array 相似文献
970.
介绍了太钢板坯连铸水处理系统的工艺流程,分析了连铸浊环水水质存在的问题。通过对冷却塔部分、铁皮坑、水泵调速等改造,以及选用新的水质稳定剂,使水质明显好转。 相似文献