螺旋盘管式相变储热单元储热性能

以石蜡作为相变材料,制作了内通流体螺旋盘管结构的相变储热单元。在对储热单元储热过程进行传热分析的基础上,利用实验手段对储热单元在不同工况下的储热性能进行了研究。通过对其储热过程中相变材料相变过程的分析,提出储热器设计的优化方案。利用实验数据得到其准则关联式,为其在工程中的应用提供了依据。     

计算机自动编程在曲轴铸造工装上的应用

通过应用计算机自动编程加工铸造工装,不仅提高了工作效率,还更好地满足了工艺需求。     

柴油机加速工况时NOx排放模拟计算

在油滴蒸发准维燃烧模型基础上,结合生成NOx的详细化学动力学机理,建立了直喷式柴油机的NOx生成模型,与实测结果对比有较好的吻合性。利用此模型对柴油机加速过程NOx排放进行了模拟计算,计算结果表明：柴油机加速工况时的NOx浓度值变化较大,有的比标定工况时还大。     

Continuity wave in the elongated bubble region of horizontal slug flow

Visualized observation on the wave feature in a horizontal slug flow was made with a high‐speed digital camera. It was found that the liquid film flow in the elongated bubble region of slug flow behaves as a continuity wave. Theoretical analysis was carried out and it reveals that the liquid film flow is a continuity wave with celerity the same as the translational velocity of the elongated bubble. The control equation for the liquid film height in the elongated bubble region was derived. The results predicted by the equation fit well with the observed data. A new conclusion was obtained that slug flow has continuity wave in it, explaining the stable slug flow wave characterization. © 2005 Wiley Periodicals, Inc. Heat Trans Asian Res, 34(8): 547–554, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20092     

TDB－100硅太阳电池仿真及P－V特性研究

采用多项式数学模型对ＴＤＢ－１００硅太阳电池实测Ｉ－Ｖ数据进行拟合，可得到电池的实验模型，该模类具有很高的精度。运用这个模型对Ｐ－Ｖ特性进行分析，并根据电池的光照及温度特性，将该模型进行扩展，得到了电池的预计模型。     

基于SGOI和CESL结构的新型应变硅NMOSFET的有限元研究

应变硅技术通过在沟道区引入适当的应变,达到提高载流子迁移率、改善MOS器件性能的目的.利用有限元法,研究了一种基于SGOI与氮化硅CESL应变结构的新型应变硅NMOSFET.结果表明,与采用单一的SGOI或CESL结构相比,两者共同作用下的新结构能更有效地提高沟道应变.增加氮化硅薄膜的本征应力、减小应变硅层厚度、适当提高锗组分,均能有效增加硅沟道区的应变量.采用有限元分析进行的模拟研究,可弥补实验测量的不足,为纳米级应变硅器件的设计和制造提供参考.     

移动互联网安全问题分析

随着我国移动互联网进入快速增长时期,移动互联网的安全问题已经成为影响其发展的重要因素之一。目前在接入安全保障上主要采用双向认证鉴权、在无线空口采用加强型加密机制以及针对WiFi接入用AES算法替代RC4,在承载网上主要部署异常流量监控和清洗技术,以及采用网络溯源技术等来解决安全问题。     

RFID防碰撞算法分析与研究

在RFID系统中碰撞是一个很常见的问题,如何有效地解决这一问题对于RFID系统来说至关重要,文中对解决防碰撞的常用方法Aloha算法和二进制树算法做了详细的研究,比较其优缺点,并提出了一种改进的RFID防碰撞算法.     

GPS轨迹测量系统在导弹飞行试验中的应用

空空导弹研制需要一系列空中系留飞行试验,以解决导弹制导系统对真实目标的截获跟踪能力。传统的系留试验由于地面试验人员无法实时掌握靶机和目标机的动态,给飞行试验结果造成了很大的不确定性;本系统利用日益广泛使用的GPS全球定位技术,从载机的导弹产品和目标机GPS吊舱接收下传的GPS信息,实时解算出目标机相对于载机位置、速度等信息,显示在数据处理软件上,从而使地面试验人员实时获取载机和目标机的相关信息,为试验指挥提供了可靠数据;实际应用结果表明,该系统大大提高了系留试验的成功率和导弹截获概率,为飞行试验节约了试验经费和时间,创造了良好的经济效益。     

A Fully Integrated 0.13- μm CMOS Digital Low-IF DBS Satellite Tuner Using a Ring Oscillator-Based Frequency Synthesizer

A low-IF fully integrated tuner for DBS satellite TV applications has been realized in 0.13-mum CMOS. A wideband ring oscillator-based frequency synthesizer having a large frequency step was used to downconvert a cluster of channels to a sliding low-IF frequency, while the second downconversion to baseband was performed in the digital domain. Eliminating the inductors and using a small-area oscillator has reduced both the parasitic magnetic and substrate coupling, allowing single-chip integration of the sensitive tuner and the noisy digital demodulator. A significant reduction in die area was achieved by using a single oscillator to cover the entire satellite TV spectrum, while a noise attenuator was cascaded with the PLL passive loop filter to reduce the equivalent VCO tuning gain. This improves PLL noise and spur performance and allows the on-chip integration of the loop filter. The digital low-IF tuner allows the use of a discrete step AGC loop that results in lower noise figure and higher linearity. Automatic signal path gain and bandwidth digital calibration was realized using replica ring oscillators. Tuner specifications include: 90 dB gain range, 10 dB noise figure at max gain, +25dBm IIP3 at min gain, 1.3deg rms integrated phase noise, <-50dBc spurs, 0.5-W power consumption from dual 1.8/3.3-V supplies, and 1.8times1.2 mm² die area