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951.
报道了一种采用内匹配技术制作的GaAs大功率晶体管。通过管芯的结构设计和工艺优化,进行了GaAs微波大栅宽芯片的研制;通过内匹配技术对HPFET(high performance FET)管芯进行阻抗匹配,实现了器件的大功率输出;通过提高栅-漏击穿电压、降低饱和压降等手段提高器件的功率和附加效率。经测试,当器件Vds=10V时,在5.3~5.7GHz频段输出功率P0≥47.8dBm(60.3W),功率附加效率PAE≥42.8%,其中在5.5GHz频率点,输出功率达到48dBm(63.1W),附加效率为46.8%。  相似文献   
952.
In this paper,a flexible and stretchable circuit has been fabricated by the printing method based on Ag NWs/PDMS composite.The randomly oriented Ag NWs were buried in PDMS to form a conductive and stretchable electrode.Stable conductivity was achieved with a large range of tensile strain (0-50%) after the initial stretching/releasing cycle.The stable electrical response is due to the buckling of the Ag NWs/PDMS composite layer.Furthermore,printed stretchable circuits integrated with commercial ICs have been demonstrated for wearable applications.  相似文献   
953.
Kwan  H.K. Tang  C.Z. 《Electronics letters》2002,38(13):645-646
An approach for designing multiplierless multilayer feedforward neural networks using quantised neurons is proposed. The design has significant merits for digital VLSI implementation in terms of reduced silicon area and increased operational speed. As compared to one-powers-of-two weights approaches of multiplierless design, the quantised neurons approach offers additional advantages of simplicity in activation function realisation and freedom in weights adaptation  相似文献   
954.
The current-voltage characteristics and frequency dependences of the impedance of composite nanostructures fabricated on the basis of layered anisotropic semiconductor p-GaSe and ferroelectric KNO3 are studied. Multilayer nanostructures were obtained by introducing nanoscale pyramidal ferroelectric inclusions into a layered GaSe matrix. Hysteresis phenomena in current-voltage characteristics and abrupt changes in the conductance and capacitance in frequency dependences of the impedance are detected. These phenomena are associated with the collective effect of electric polarization switching in nanoscale 3D ferroelectric inclusions in the layered matrix, features of its local deformation, and polytype phase transitions in this matrix. X-ray, atomic-force microscopy, and impedance studies in a low (B < 400 mT) magnetic field show that the electrical characteristics of nanostructures are associated with the Maxwell-Wagner effect in nanostructures, the formation of quantum wells in GaSe during deformation of crystals in the region of nanoscale inclusion localization, and carrier tunneling in the structures.  相似文献   
955.
This paper mainly deals with the problem of detecting and identifying target in close range, the performance of which will be effected by the radiometer’s parameters and target’s characteristics. According to the relationship between the range equation of the Passive Millimeter Wave (PMMW) and these parameters, we present a convenient statistical method based on PMMW image detection to solve the inherent problem by statistical radiometer parameters, which can be achieved by the W band radiometer experimental data. Finally, we validate the method by simulation and experiment. The results show that the method is convenient for detecting and identifying target in close range.  相似文献   
956.
A novel in situ decomposition/reduction approach is developed to manu­facture hollow core, magnetic, and mesoporous double‐shell nanostructures (HMMNSs) via in situ decomposition and reduction of a β‐FeOOH nanorod core and organosilicate‐incorporated silica‐shell precursor. The formed HMMNSs are then aminated by silanization for further covalent conjugation to rhodamine B isothiocyanate (RBITC) and poly(ethylene glycol) (PEG) chains. The resultant RBITC‐grafted and PEGylated nanocomposites (HMMNS–R/Ps) have excellent blood compatibility and very low cytotoxicity towards HeLa and MCF‐7 cells, and can be taken up by cancer cells effectively in a dose‐dependent manner, as confirmed by in vitro flow cytometry, confocal luminescence imaging, and magnetic resonance imaging (MRI) studies. In vivo MRI studies coupled with Prussian blue staining of slides from different organs show that the nanocomposites preferentially accumulate in liver and spleen after intravenous injection, which suggests a potential application of the nanocomposites as MRI contrast agents. Importantly, the HMMNS–R/P nanocomposites show high loading capacity for water‐insoluble anticancer drugs (docetaxel or camptothecin) owing to the presence of a large inner cavity and enhanced surface area and pore volume. Furthermore, the drug‐loaded nanocomposites exhibit greater cytotoxicity than the corresponding free drugs. These results confirm that the HMMNS–R/P nanocomposites are promising candidates for simultaneous bioimaging and drug delivery.  相似文献   
957.
业务全面IP化、网络全面宽带化,成为这个时代的两大方向,并在省内干线传送网领域形成了富有激情的碰撞。“面向全IP业务的光传送网”显示出越来越明晰的框架,引领着最新的技术潮流。从未来来看,网络的IP化、扁平化不可逆转,省内干线传送网络最终会成为IP over Optical的架构。  相似文献   
958.
比较研究了InGaAs/GaAs量子链和量子点的稳态和瞬态光学特性.实验发现,量子链的荧光寿命有很强的探测能量依赖关系,而量子点的荧光寿命随能量变化较小;量子链的荧光寿命随着激发功率迅速增加,高功率时趋于饱和,而量子点的荧光寿命随激发功率变化缓慢;此外,量子链样品的荧光上升时间也比量子点的小得多.这些结果清楚表明,在量子链结构中,参与发光的载流子之间存在很强的耦合和输运.进一步分析表明,这种耦合作用主要发生在量子链方向.荧光的偏振特性进一步证实了这一点.  相似文献   
959.
The study of current-voltage characteristics of amorphous film samples of the Se1?x S x system (x = 0, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5) showed that carrier transport occurs by the mechanism of one-carrier injection space-charge-limited currents, involving two groups of traps, i.e., shallow ones (E t1) corresponding to charged intrinsic defects C 1 ? and caused by dangling bonds in selenium and deep traps E t2 also corresponding to charged intrinsic defects C 3 + in selenium. It has been shown that a change in the Se-S system composition significantly affects both the charge transport mechanism and trap parameters, i.e., energy states and concentrations.  相似文献   
960.
Photoluminescence, optical reflectance and electro-reflectance spectroscopies were employed to study an AlGaAs/GaAs multiple-quantum-well based resonant Bragg structure, which was designed to match optical Bragg resonance with the exciton-polariton resonance at the second quantum state in the GaAs quantum wells. The structure with 60 periods of AlGaAs/GaAs quantum wells was grown on a semi-insulating substrate by molecular beam epitaxy. Broad and enhanced optical and electro-reflectance features were observed when the Bragg resonance was tuned to the second quantum state of the GaAs quantum well excitons manifesting an enhancement of the light-matter interaction under double-resonance conditions. By applying an alternating electric field, we revealed electro-reflectance features related to the x(e2-hh2) and x(e2-hh1) excitons. The excitonic transition x(e2-hh1), which is prohibited at zero electric field, was allowed by a DC bias due to brake of symmetry and increased overlap of the electron and hole wave functions caused by electric field.  相似文献   
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