局用射频线缆在工程中的应用

简要介绍局用射频线缆的应用情况、线缆的选型、常用线缆型号及指标,最后提出了在工程设计中,应充分考虑原有线缆及拟用线缆的电气指标、物理性能、应用场合等多种因素。

宇航用射频同轴电缆组件放电抑制技术探究

对于宇航用射频同轴电缆组件来讲,当航天器处于入轨或者正轨运行状态时,都必须要带有一定电量。否则,系统将会无法有效运行。根据相关调查和研究可以发现:在其运行过程中,会在很大程度上受到低气压放电效应和针孔微放电效应的影响,从而对功率射频同轴连接器性能和可靠性产生较大影响。为此,本篇文章在综合了相关调查和研究之后完成,针对现阶段工作中所出现的各种问题,对其进行合理化分析。主要从功率阈值、通气孔、导体间隙尺寸等多个角度进行分析。综合相关问题对其进行有效分析,有效避免了不必要问题的发生,对于电缆组件运输功率信号稳定性和可靠性的提升产生了积极作用。

量子线中空穴被δ函数型杂质散射时的波函数匹配条件

对量子线 (量子薄层 )中的空穴哈密顿的约化问题进行了讨论 。

注射用灯盏花素对麻醉犬急性心肌缺血的影响

目的 :通过麻醉犬心肌缺血实验研究注射用灯盏花素的抗心肌缺血作用。方法 :采用结扎麻醉犬左冠状动脉前降支(LAD)造成急性心肌缺血的病理模型 ,采用心外膜电图 (EECG)、肌酸激酶 (CK)、乳酸脱氢酶 (LDH)、心肌梗塞范围等指标观察注射用灯盏花素对急性心肌缺血的作用。结果 :注射用灯盏花素可降低麻醉犬冠脉结扎所致ST段升高总mV数 (Σ ST)和ST段升高总点数 (N ST) ,减少血清中CK、LDH的释放 ,减小心肌梗塞范围。结论

射频同轴电缆组件在太空中应用的技术保障浅谈

射频同轴电缆组件作为卫星载荷通讯必备的组件,长期以来对进口的依赖程度较高。随着近几年国际宇航市场环境的变化,再加上国内倡导的“自主可控”,以及商业卫星载荷对成本的敏感性,射频同轴电缆组件的完全自主国产化,是该市场发展的大方向。笔者从多年的射频同轴电缆组件国产化研发工作实践中,总结出了其在太空中应用的设计技术基础,并做出浅析。

注射用核糖核酸Ⅱ对消化道肿瘤的临床疗效观察

目的观察注射用核糖核酸II(以下简称:核II)对晚期消化道肿瘤患者的疗效和安全性。方法 80例晚期消化道肿瘤患者单盲随机分为核II组和对照组,对照组采用单纯化疗方案,核II组于化疗同时静脉滴注核II 200 mg/d,连续45 d(一个疗程)后检测患者T细胞亚群的变化、外周白细胞变化、毒副不良反应发生率、并通过Karnofsky评分评价患者的生活质量。结果①核II组化疗后CD3、CD4、CD56的阳性率明显高于对照组(P<0.05)。②核II组化疗后的白细胞下降程度、不良反应II度发生比例均明显低于对照组(P<0.05)。③核II组化疗后Karnofsky评分升高比例57.5%明显高于对照组42.5%。结论①核II可刺激T细胞成熟和分化,显著提高机体免疫功能。②核II可减少化疗过程中患者白细胞的下降、毒副反应的发生。③化疗联合核II可以有效改善患者生活质量。

基于WindowsNT的复杂目标GRECO建模

ＧＲＥＣＯ技术是目前分析高频区复杂目标雷达散射截面（ＲＣＳ）最有效的方法之一。对复杂目标而言，应用ＧＲＥＣＯ方法的一个重要工作就是对目标的几何造型进行准确地建模，这样才能获得令人满意的结果。本文结合ＣＲ样条建模理论，利用（Ｇ１，Ｋ＝１）几何样条及其张量积曲面，阐述了在ＷｉｎｄｏｗｓＮＴ环境下利用ＶＣ４０与ＯｐｅｎＧＬ为ＧＲＥＣＯ方法进行建模的机制。

长沙磁浮快线对铁路无线电子设备的电磁干扰分析

针对长沙磁浮快线工程的特点,通过现场模拟测试,对比相关标准规范,分析了铁路无线电子设备受中低速磁浮工程电磁干扰的影响情况。

Total Dose Radiation-Hard 0.8μm SOI CMOS Transistors and ASIC

This paper presents the total dose radiation performance of 0.8μm SOI CMOS devices fabricated with full dose SIMOX technology. The radiation performance is characterized by threshold voltage shifts and leakage currents of transistors and standby currents of ASIC as functions of the total dose up to 500krad（Si）. The experimental results show that the worst case threshold voltage shifts of front channels are less than 320mV for pMOS transistors under off-gate radiation bias at 1Mrad（Si） and less than 120mV for nMOS transistors under on-gate radiation bias. No significant radiation-induced leakage current is observed in transistors to 1Mrad （Si）. The standby currents of ASIC are less than the specification of 5μA over the total dose range of 500krad（Si）.

Adaptive channel estimation based on pilot signals and transform-domain processing in SISO/MIMO OFDM systems

Based on the transform-domain characteristics of pilot signals,a band suppression filter is used as a transform-domain filter to restrain the interference of noise in channel estimation.The performance effect on channel estimation for an orthogonal frequency division multiplex （OFDM） system by different energy coefficients in the transform domain and the energy coefficient under the different signal-to-noise ratios （SNR） are also analyzed.A new energy coefficient expression is deduced.It is theoretically proven that dynamically selecting an energy coefficient can significantly improve the performance of channel estimation.Simulation results show that the proposed algorithm can achieve better performance close to the theoretic bounds of perfect channel estimation. The algorithm is adapted to single-input single-output （SISO） OFDM and multi-input multi-output （MIMO） OFDM systems.

Estimation of Net Primary Productivity of Terrestrial Vegetation in China by Remote Sensing

Among the many approaches for studying the net primary productivity (NPP), a new method by using remote sensing was introduced in this paper. With spectral information source (the visible band, near infrared band and thermal infrared band) of NOAA-AVHRR, we can get the relative index and parameters, which can be used for estimating NPP of terrestrial vegetation. By means of remote sensing, the estimation of biomass and NPP is mainly based on the models of light energy utilization. In other words, the biomass and NPP can be calculated from the relation among NPP, absorbed photosynthetical active radiation (APAR) and the rate (epsilon) of transformation of APAR to organic matter, thus: NPP = ( FPAR x PAR) x [epsilon * x sigma (T) x sigma (E) x sigma (S) x (1 - Y-m) x (1 - Y-g)]. Based upon remote sensing ( RS) and geographic information system (GIS), the NPP of terrestrial vegetation in China in every ten days was calculated, and the annual NPP was integrated. The result showed that the total NPP of terrestrial vegetation in China was 6.13 x 10(9) t C . a(-1) in 1990 and the maximum NPP was 1 812.9 g C/m(2). According to this result, the spatio-temporal distribution of NPP was analyzed. Comparing to the statistical models, the RS model, using area object other than point one, can better reflect the distribution of NPP, and match the geographic distribution of vegetation in China.

Micromechanical Tunable Optical Filter

A micromachined vertical cavity tunable filter with AlGaAs/GaAs distributed Bragg reflector is presented.This filter can be electrostatic tuning over a range of 28nm with an applied voltage of 7V.

Mutagenic Effect of ^(60)Co γ-rays Irradiation on Turf Characteristics of Buchloe dactyloides (Nutt.) Engelm.

[Objective] This study aimed to investigate the mutagenic effect of 60 Co γ-rays irradiation on turf characteristics of Buchloe dactyloides （Nutt.） Engelm. [Method] Buffalo grass were irradiated with 60 Co γ-rays at five different radiation intensities （1 200, 1 400, 1 600, 1 800, 2 000 Gy） to determine the related turf characteristics and analyze the mutagenic effect of 60 Co γ-rays at different radiation intensities on buffalo grass. [Result] Germination rates of buffalo grass irradiated by different radiation intensities of 60 Co γ-rays varied inconsistently, and the root length and bud length were shorter than the control; compared with the control, the height of irradiated seedlings was significantly reduced, and the number of tillers, plant height, leaf length and leaf blade width were smaller than the control; however, the stolon length, stolon diameter and number of stolon nods had no significant difference compared with the control. [Conclusion] This study laid foundation for determining the appropriate radiation intensity of 60 Co γ-rays and selecting useful mutants of buffalo grass.

Protective effect of Radix Astragali injection on immune organs of rats with obstructive jaundice and its mechanism

AIM: To observe the protective effect of Radix Astragali injection on immune organs (lymph nodes, spleen and thymus) of rats with obstructive jaundice (OJ) and its mechanism. METHODS: SD rats were randomly divided into sham-operation group, model control group and Radix Astragali treatment group. On days 7, 14, 21 and 28 after operation, mortality rate of rats, pathological changes in immune organs, expression levels of Bax and nuclear factor (NF)-κB p65 proteins, apoptosis indexes and serum tumor necrosis factor (TNF)-α level in spleen and thymus were observed, respectively.RESULTS: Compared to model control group, the number of dead OJ rats in Radix Astragali treatment group decreased (P > 0.05). The TNF-α level (27.62 ± 12.61 vs 29.55 ± 18.02, 24.61 ± 9.09 vs 31.52 ± 10.95) on days 7 and 21, the pathological severity score for spleen [0.0 (0.0) vs 0.0 (2.0) on days 7 and 14 and for lymph nodes [0.0 (1.0) vs 1.0 (2.0), 1.0 (0.0) vs 2.0 (1.0)] on days 21 and 28, the product staining intensity and positive rate of Bax protein in spleen [0.0 (0.0) vs 1.0 (2.0), 0.0 (1.0) vs 2.0 (1.5) and thymus [0.0 (0.0) vs 1.0 (2.0), 0.0 (1.0) vs 2.0 (1.5)] on days 14 and 28, the apoptotic indexes [0.0 (0.0) vs 0.0 (0.01)] in spleen and thymus [0.0 (0.0) vs 0.0 (0.01) on days 14 and 21 were significantly lower in Radix Astragali treatment group than in model control group (P < 0.05). CONCLUSION: Radix Astragali has protective effects on immune organs of OJ rats by relieving the pathological changes in immune organs, reducing TNF-α level and inhibiting Bax expression and apoptosis in spleen and thymus.

Simultaneous Determination of Ceftazidime and Tazobactam in Injectable Powder by Reversed-Phase High Performance Liquid Chromatography

A reversed-phase high performance liquid chromatographic (RP-HPLC) method wasdeveloped and validated for the simultaneous deteimination of ceftazidime and tazobactam ininject-able powder. Methods Chromatography was carried out on Zorbax 300SB-C_(18) column using amixture of methanol and aqueous solution of phosphate buffer (pH = 5.6) as mobile phase. The UVdetection wavelength was 220 run. Results The linear ranges of ceftazidime and tazobactam were 0.62- 631.8 μg·mL^(-1) and 0.66 - 677.50 μg·mL^(-1), respectively. The average recoveries were 98.8%- 101.4% for ceftazidime, and 99,1% - 100.2% for tazobactam. The RSD values of inter-day andintra-day assays were lower than 1.5% for ceftazidime and 2.6% for tazobactam. Conclusion Thismethod is reproducible, simple, precise, and rapid for the quality control of ceftazidime andtazobactam in injectable powder.

Preparation of Macroporous TiO2 Ceramic Based on Membrane Jet-flow Emulsification

A novel method to prepare macroporous TiO2 ceramic, based on membrane emulsification was reported.To solve the paradox between the instability of nonaqueous emulsion and long emulsification time required by themembrane emulsification, a two-stage ceramic membrane jet-flow emulsification .was. proposed. Discussion wasconducted on the evolution of droplet size with time, which followed the Ostwalcl npemng theory. And a monodispersed nonaqueous emulsion with an average droplet size of 1.6μm could beprepared. Using the emulsion, as atemplate, TiO2 ceramics with an average pore size ot 1.1 μm were obtaineed. Tne material could be prospectivelyused for preparation of catalysts, adsorbents, and membranes.

Clinical usefulness of ^(18) F-FDG PET/CT in the restaging of esophageal cancer after surgical resection and radiotherapy

AIM： To evaluate the clinical usefulness of lSF-fluorodeoxyglucose positron emission and computed tomography QSF-FDG PET/CT） in restaging of esophageal cancer after surgical resection and radiotherapy. METHODS： Between January 2007 and Aug 2008, twenty histopathologically diagnosed esophageal cancer patients underwent 25 PET/CT scans （three patients had two scans and one patient had three scans） for restaging after surgical resection and radiotherapy. The standard reference for tumor recurrence was histopathologic confirmation or clinical follow-up for at least ten months after ^18F-FDG PET/CT examinations. RESULTS： Tumor recurrence was confirmed histopathologically in seven of the 20 patients （35%） and by clinical and radiological follow-up in 13 （65%）. ^18F-FDG PET/CT was positive in 14 patients （68.4%） and negative in six （31.6%）. ^18F-FDG PET/CT was true positive in 11 patients, false positive in three and true negative in six. Overall, the accuracy of ^18F-FDG PET/CT was 85%, negative predictive value （NPV） was 100%, and positive predictive value （PPV） was 78.6%.The three false positive PET/CT findings comprised chronic inflammation of mediastinal lymph nodes （n = 2） and anastomosis inflammation （n = 1）. PET/ CT demonstrated distant metastasis in 10 patients. ^18F-FDG PET/CT imaging-guided salvage treatment in nine patients was performed. Treatment regimens were changed in 12 （60%） patients after introducing ^18F-FDG PET/CT into their conventional post-treatment follow-up program. CONCLUSION： Whole body ^18F-FDG PET/CT is effective in detecting relapse of esophageal cancer after surgical resection and radiotherapy. It could also have important clinical impact on the management of esophageal cancer, influencing both clinical restaging and salvage treatment of patients.

Mechanism of wet shotcrete interacting with rock in support systems

In order to have a good understanding of the behavior of wet shotcrete as a support element interacting with the rock mass,mechanism of wet shotcrete interacting with rock in support systems was analyzed through theoretical,numerical study and analytical analysis.A new model of distribution of rock stress state after wet shotcrete was applied,which includes shotcrete layer,composite layer,strengthening layer,plastic layer and elastic layer,and a full illustration of the rock mass stress state was given after shotcrete interacting with rock mass.At the same time,numerical analysis with FLAC gives a stress distribution along the monitor line,respectively,at the sidewall and roof of the tunnel.The displacement obviously decreases with the depth of rock,the tangential stress for tunnel supported by shotcrete is lower than that without shotcrete,and radial stress for tunnel supported by shotcrete is higher than that without shotcrete.It has been demonstrated by AIRY'S stress function,which gives a reasonable solution.Finally,the application of wet shotcrete in Jinfeng Gold Mine shows that the displacement of tunnel decreases obviously in sidewall and roof.

New Reflection Principles for Maxwell's Equations and Their Applications

Some new reflection principles for Maxwell's equations are first established, which are then applied to derive two novel identifiability results in inverse electromagnetic obstacle scattering problems with polyhedral scatterers.

An Enhanced Physically Based Scour Model for Considering Jet Air Entrainment

Based on systematic experiments on the influence of air entrainment on rock block stability in plunge pools impacted by high-velocity jets,this study presents adaptations of a physically based scour model.The modifications regarding jet aeration are implemented in the Comprehensive Scour Model(CSM),allowing it to reproduce the physical-mechanical processes involved in scour formation concerning the three phases;namely,water,rock,and air.The enhanced method considers the reduction of momentum of an aerated jet as well as the decrease of energy dissipation in the jet diffusive shear layer,both resulting from the entrainment of air bubbles.Block ejection from the rock mass depends on a combination of the aerated time-averaged pressure coefficient and the modified maximum dynamic impulsion coefficient,which was found to be a constant value of 0.2 for high-velocity jets in deep pools.The modified model is applied to the case of the observed scour hole at the Kariba Dam,with good agreement.