频变交叉耦合带通滤波器的耦合矩阵综合研究

综合代表滤波器拓扑结构和特性的耦合矩阵是交叉耦合滤波器设计的重点。提出了一种基于广义特征值的优化综合方法,通过非线性最小二次求解,将耦合矩阵的广义特征值逼近至广义切比雪夫响应多项式传输函数零极值参考点,优化求解出带有频变交叉耦合带通滤波器的耦合矩阵。通过3个数值实例演示了该方法,并验证其有效性。这是对经典带通滤波器耦合矩阵综合方法的补充,为频变交叉耦合滤波器的设计建立了基础。     

高粘度系统油泵粘性摩擦功耗的探讨及应用

针对攀钢1450热轧板厂1250系统运行中存在的问题,对系统摩擦功耗进行了分析测试,发现油泵功率损耗较大;根据流体力学流体内摩擦定理及积分原理,对油泵粘性摩擦功耗进行了初步探讨;根据系统摩擦功耗测试和粘性摩擦功耗分析结果,提出系统改进方案并实施,改造效果较好;并发现油泵粘性摩擦功耗分析结果,对高粘度系统的精确设计有着十分重要的意义。     

基于Matlab的无花果成熟度识别技术

利用matlab和图像处理技术对无花果果实进行处理识别，该系统可以快速、高效的辨别出七八分熟以上的无花果果实，进而提高了无花果自动化识别水平，同时为无花果采摘机器人的研究做了准备。无花果目前已知有八百个品种，绝大部分都是常绿品种，但目前市场上常见的大约在十种以内。并以布兰瑞克、金早、金傲芬、紫蕾、波姬红、绿早、青皮几种中国最受欢迎的无花果品种为对象，通过MATLAB软件研究了判别无花果成熟度的算法,分别依据果实裂口和颜色变化进行判别。综合两种算法对果实成熟度进行判断，正确率达到89.5%。     

TiB2-SiC粉末喷雾造粒及其等离子喷涂沉积机理研究

利用喷雾干燥对TiB_2-SiC复合粉末进行造粒,研究了浆料固含量、粘结剂含量及SiC含量对喷雾干燥粉体颗粒形貌等的影响。采用大气等离子喷涂技术,以抛光的石墨为基体,在不同预热温度和不同喷距下对TiB_2-SiC粉末进行粒子收集,研究不同工艺参数对TiB_2-SiC粒子铺展形貌的影响,并制备了TiB_2-SiC涂层。结果表明:当浆料固含量为50%,粘结剂含量为5%,SiC含量为10%时,喷雾造粒获得球形度高、流动性好的TiB_2-SiC粉末;随着基体预热温度的升高,喷距的增大,扁平粒子的溅射逐渐减弱,形成规则的圆盘状粒子;在等离子焰流作用下,TiB_2-SiC粒子熔化加速并与基体发生碰撞,熔融粒子扁平化,急速冷却凝固,不断堆叠、搭接为宏观涂层。     

The productive potentials of sweet sorghum ethanol in China

As one of the important non-grain energy crops, sweet sorghum has attracted the attention of scientific community and decision makers of the world since decades. But insufficient study has been done about the spatial suitability distribution and ethanol potential of sweet sorghum in China. This paper attempts to probe into the spatial distribution and ethanol potential of sweet sorghum in China by ArcGIS methods. Data used for the analysis include the spatial data of climate, soil, topography and land use, and literatures relevant for sweet sorghum studies. The results show that although sweet sorghum can be planted in the majority of lands in China, the suitable unused lands for large-scale planting (unit area not less than 100 hm²) are only as much as 78.6 × 10⁴ hm²; and the productive potentials of ethanol from these lands are 157.1 × 10⁴–294.6 × 10⁴ t/year, which can only meet 24.8–46.4% of current demand for E10 (gasoline mixed with 10% ethanol) in China (assumption of the energy efficiency of E10 is equivalent to that of pure petroleum). If all the common grain sorghum at present were replaced by sweet sorghum, the average ethanol yield of 244.0 × 10⁴ t/year can be added, and thus the productive potentials of sweet sorghum ethanol can satisfy 63.2–84.9% of current demand for E10 of China. In general, Heilongjiang, Jilin, Inner Mongolia and Liaoning rank the highest in productive potentials of sweet sorghum ethanol, followed by Hebei, Shanxi, Sichuan, and some other provinces. It is suggested that these regions should be regarded as the priority development zones for sweet sorghum ethanol in China.     

Optimal radar waveform design method in colored and non-Gaussian noise

This paper considers the design of optimal waveforms for detection of point targets in colored non-Gaussian noise. We present the likelihood ratio processor and derive an expression for its output signal-to-noise ratio (SNR), and then use this as the basis for a cost function in a waveform design optimization which is solved by using a one dimensional alternating maximization algorithm. Finally simulations are performed to verify the effectiveness of the new waveforms.     

An Evaluation of China’s Water Footprint

The water footprint is an indicator of freshwater consumption that looks not only at direct water consumption of a consumer or producer, also at the indirect water consumption. The water footprint can be regarded as a comprehensive indicator of freshwater resources appropriation, next to the traditional and restricted measure of water withdrawal. Based on the concept and calculating method of water footprint, this paper estimates the water footprint of China in 2007. The result shows that the total water footprint of China is 856.34 × 10⁹ m³ and the per capita water footprint is 648.11 m³/year. The spatial difference of per capita water footprint is obvious among all provinces of China. Generally, the more developed cities, the southern and coastal provinces have a higher per capita water footprint, lower water footprint intensity and higher efficiency of water consumption, while the North West China has lower water utilization efficiency. China is one of the thirteen water scarce countries in the world and spatial distribution of water resources is non-uniform. In addition to the virtual water trade, government should apply advanced technology and best available management practices, improve the efficiency of water use, reduce virtual water content per unit product, and continue nation-wide readjustment of industrial structure to guarantee an efficient use of limited water resources.     

一种复杂地物目标近垂直后向散射系数反演方法

复杂地物目标的近垂直后向散射特征是影响雷达高度表回波波形的重要因素之一。对近垂直后向散射系数的获取主要采用基于参数模型的实测数据拟合方法,但一般只适用于地势平坦且介质相对单一的地海面目标。本文基于机载雷达高度表,针对复杂地物目标的距离-多普勒图像仿真实验数据和实测数据,利用距离-多普勒域和地球空间域的映射关系,提出一种后向散射系数的反演算法,并对得到的后向散射系数进行定量分析。实验验证了提出的反演算法具有一定的适用性和参考性。     

基于硅基IPD技术的新型S波段带通滤波器设计

将无源器件内埋或集成在封装基板中,是射频系统级封装(SIP)的小型化面临的首要问题之一.基于硅基集成无源器件(IPD)技术,借鉴经典的级联四角元件(CQ)滤波器拓扑,提出一种四电感互耦结构.利用集总LC谐振器和分布式互感耦合原理,在交叉耦合节点处以加载电容的方式引入频变耦合节点,实现了一款新颖的S波段四阶带通滤波器,尺寸仅为1.5 mm×l mm,其通带内最小插损约为-3.5 dB@ 2.8 GHz,-1 dB带宽为2.63～2.96 GHz,在带外形成两个传输零点位置:-41.5 dB@2.29 dB@3.34 GHz.该滤波器结构形式新颖,可以整体集成到硅基板中,为射频系统级封装一体化集成提供支持.