A Multi-Finger Si_(1-x)Ge_x/Si Heterojunction Bipolar Transistor for Wireless Power Amplifier Applications

A large area multi-finger configuration power SiGe HBT device(with an emitter area of about 880μm~2)was fabricated with 2μm double-mesa technology.The maximum DC current gain β is 214.The BV_(CEO) is up to 10V,and the BV_(CBO) is up to 16V with a collector doping concentration of 1×10~(17)cm~(-3) and collector thickness of 400nm.The device exhibits a maximum oscillation frequency f_(max) of 19.3GHz and a cut-off frequency f_T of 18.0GHz at a DC bias point of I_C=30mA and V_(CE)=3V.MSG(maximum stable gain)is 24.5dB,and U(Mason unilateral gain)is 26.6dB at 1GHz.Due to the novel distribution layout,no notable current gain fall-off or thermal effects are observed in the I-V characteristics at high collector current.

历史时期黄土高原生态环境建设分析

采用科学史观简要分析了黄土高原生态环境演变的历史过程。通过分析认为 ,历史时期的黄土高原生态环境演变不再单纯表现为自然过程 ,而是与人类活动密切相关的人地互动过程。人为因素黄土高原生态环境历史演变具有双重意义 ,既通过耕种对自然环境破坏 ,还进行农业生态环境建设 ,提高土地承载能力 ,其主要是由不同的环境观和社会因素造成的。人类对生态环境影响以资源利用为主 ,有意识的建设活动较少 ,农业生态环境建设成就巨大 ,生态环境演变具有明显历史进程 ,被动的生态环境保护和恢复对生态环境演变有特殊意义 ,历史时期黄土高原农业生态环境建设实践及其成效在农田水利环境、土壤环境、水土保持等方面表现突出。历史时期生态环境建设研究具有现实意义 ,在当今西部大开发机遇下 ,应借鉴历史经验 ,加快黄土高原生态环境建设。建议采用科学的环境观指导实践 ,加大科技投入和市场调剂 ,减小黄土高原地区粮食压力 ,实现较劣土地的生态恢复 ,使自然生态环境修复和农业生态环境建设同步进行 ,建设结构合理的水土保持型大农业生态环境。

Density functional studies of diatomic LaO to LuO

Bond distances, vibrational frequencies, electron affinities, ionization potentials, dissociation energies and dipole moments of the title molecules in neutral, positively and negatively charged ions were studied by use of density functional method. Ground electronic state was assigned for each molecule. The bonding patterns were analyzed and compared with both the available data and across the series. It was found that besides ionic component, covalent bonds are formed between the metal s, d and f orbitals and oxygen p orbitals. Contrary to the well known lanthanide contraction, the bond distance is not regular from LaO to LuO for both neutral and charged molecules. An obvious population at 5d orbital was observed through the lanthanide series. 4f electrons also participate the chemical bonding for CeO to NdO and TbO to TmO. For EuO, GdO, YbO and LuO, 4f electrons tend to be localized. The spin multiplicity is regular for neutral and charged molecules. The spin multiplicity of the charged molecules can be obtained by -1 (or +1 for TbO+, DyO+, YbO- and YbO+) compared with the corresponding neutral molecules.

W-183 NMR characterization of rare earth heteropolymetalates in aqueous solution

W-183 NMR spectra were obtained for [La(AsW11O39)(2)](11-), [La(As2W17O61)(2)](17-), [La(SiW9Mo2O39)(2)](13-), [LaSb9W21O86](16-), [LaAs4W40O140](25-) and alpha-, beta-[(CeO)(3) . (SiW9O34)(2)](14-) complexes, Tungsten NMR studies showed that the C-s symmetry of the square antiprism for [La(ASW(11)O(39))(2)](11-) and [La(As2W17O61)(2)](17-) anions keep constant in aqueous solution; the lanthanide accupied the central S-1 site in [LnSb(9)W(21)O(86)](16-) and [LnAs(4)W(40)O(140)](25-) complexes, respectively, and lanthanide metal cations gave [(CeO)(3) . (SiW9O34)(3)](14-) type of complexes with SiW9O3410-.

Photovoltaic Properties and Quantum Size Effect in Nanocrystalline CeO2

Different size. nanocrystallines CeO2 were synthesized and their diffuse reflectance absorption spectra have heen measured. The absorption band in the region from 300 to 450 nm was assigned to the O2p-Ce2 4f transition. It was found that a strongly red-shifted broad continuum of the absorption band occured as the decrease of the partical size. We have also measured the surface photovoltage as function of wavelength by SPS technique. And the absorption band was resolved to two peaks with different photovoltaic properties. Photovoltaic quantum size effect was observed by FMSPS measurement.

(η~5-C_5H_5)_3Ln·OC_4H_8(Ln=Ce,Er)的合成及晶体结构

用无水硝酸铈铵[(NH_4)_2Ce(NO_3)_6]与环戊二烯钠(C_5H_5Na)在四氢呋喃中按1:6摩尔比反应,得到(η~5-C_6H_5)_3Ce·OC_4H_8;用ErCl_3·nTHF与环辛二烯钾(C_8H_(11)K)按等摩尔比于-78℃反应,升至室温,再按1:2摩尔比加入C_5H_5Na,得到了(η~5-C_5H_5)_3Er·OC_4H_8.两配合物晶体结构测定结果表明都属单斜晶系P2_(1/n)空间群.Ce配合物与已测定过的(η~5-C_5H_5)_3Ln·OC_4H_8(Ln=La,PrNd,Gd,Dy,Y,Lu)的晶体结构不是同构物:而Er配合物则是同构物.Ce配合物中的Ce—O、Ce—Cent(环戊二烯环中心)和平均Ce—C(η~5)键长不符合镧系收缩规律,而Er配合物的键长符合.这说明在(η~5-C_5H_5)_3Ln·OC_4H_8同构系列中在Ce和Dy有两个断点,但不存在所谓的“钆断现象”,因为Y,Er,Lu配合物的Ln—O和Ln—C(η~5)和Ln—Centroid距离不大于Gd的相应值.

服务机器人路径规划技术研究

随着技术的发展和数字产品的价格下降，家用机器人必将成为未来数字家庭的主导。正如家用机器人生产厂商iRobot的CEO科林·安格尔所说：“我认为，完全有理由想像，10年之后每个家庭都将拥有一台机器人。”路径规划技术是移动机器人导航系统中不可缺少的重要组成部分，不仅是移动机器人完成任务的安全保障，同时也是移动机器人智能化程度的重要标志。 本论文以新松公司“家用服务机器人的研究开发”项目为背景，对服务机器人的路径规划系统中的重点和难点问题进行了深入的研究，主要工作如下： 在嵌入式微处理器ARM7上实现了服务机器人的路径规划系统，完成了超声波传感器和红外传感器的采集和标定，并通过仿真研究和实验研究两方面对机器人的路径规划系统进行分析和设计。 在MATLAB GUI的仿真平台上，采用改进斥力势场函数解决了障碍物附近目标点不可达问题，通过引入引导点解决机器人在‘U’型区域内的震荡问题。在实验中，首先采用改进势场函数实现了机器人的折线规划方法，基于此算法，实现了机器人在固定范围内漫游的功能；通过改进折线规划方法，提出了弧形规划算法；通过引入人工协调场，解决了机器人、障碍物与目标点在一条直线上时与长形障碍物的碰撞问题；最后再加上各种安全措施，保证机器人在躲避障碍物的同时，能以一种比较平滑、优美的曲线到达目标点。 本论文首先在仿真中实现基本的规划算法，以服务机器人为平台，通过实验，不断发现新问题，提出新的改进算法，最后再在实验中进行验证。实验结果表明本文设计的路径规划算法能够实现机器人以平滑优美的曲线在复杂环境中的路径规划功能。

Comparative study by infrared spectroscopy and microcalorimetry of the CO adsorption over supported palladium catalysts

The adsorption of CO on Al(2)O(3), ZrO(2), ZrO(2)-SiO(2), and ZrO(2)-La(2)O(3) supported Pd catalysts was studied by adsorption microcalorimetry and infrared (TR) spectroscopy. Some interesting and new correlations between the results of microcalorimetry and IR spectroscopy have been found. The CO is adsorbed on palladium catalysts in three different modes: multibonded (3-fold), bridged (2-fold), both on Pd(lll) and (100) planes, and linear (1-fold) adsorbed species. The corresponding differential adsorption heats lie in the field of high (210-170 kJ/mol), medium (140-120 kJ/mol), and low (95-60 kJ/mol) values, respectively. The nature of the support, the reduction temperature, and the pretreatment conditions affect the surface structure of the Pd catalysts, resulting in variations in the site energy distribution, i.e., changes in the fraction of sites adsorbing CO with specific heats of adsorption. Moreover, the CeO(2); promoter addition weakens the adsorption strength of CO on palladium. Based on the exposed results, a correctness factor, which considers the percentages of various CO adsorption states, must be introduced when one calculates the Pd dispersion using CO adsorption data.

上市公司经营管理者绩效－报酬与激励机制初探

This research aims at the CEO's (chief executive officer) incentive-reward system and investigates 456 companies that have come into the market. The structure and level of agent reward are analyzed. And the problem in the incentive-reward mechanism is brought forward. The agent's payments are poor comparing to their contributions. And stock is not a primary incentive. Bonus compensation is still the dominant incentive means. By questionnaire and interview, it was fond that matriel need was rank first among these CEOs'needs. These foundinds indicate that the agents' payment is too poor to work as an effective incentive. The corporation's agent incentive is not enough in fact. The two reasons about this problem lie in our institutions and traditional opinions about commerce. To solve this matter, we must establish a scientific and reasonable evaluation system and incentive-reward system. At the same time, the market system and corporation management mechanism are absolutely need.