圆抛物面薄壳在冲击波载荷下变形的实验研究

目的　研究中心固定支撑的圆抛物面薄壳体在爆炸冲击波载荷作用下的变形效应; 方法　将圆抛物面薄壳体置于裸装药柱产生的爆炸场中,测定在不同冲击波载荷作用下壳体表面的变形量,分析了壳体的变形特点和变形规律;通过相似理论将实验研究结果加以推广; 结果　得到了壳体变形量的有关曲线和关系式;结论　该研究结果可以为雷达天线在爆炸冲击波作用下的变形程度分析提供参数;     

基于马尔可夫随机场的曲面光顺算法

利用最小均方（LMS）线性预测方法检测曲面型值点，对误差较大的坏点采用预测值进行修正，从而有效地避免了坏点对曲面光顺效果的影响。基于马尔可夫随机场（MRF）的局部特性，采用二阶邻域内数据点的线性组合代替原型值点，选择适当的加权系数，依次对各型值点进行修改，即可在保证曲面精度的前提下实现曲面光顺。计算结果证明，此算法结构简单，运算速度快，修改能力强，对不同形式的参数曲面都可以取得良好的光顺效果。     

基于共空间模式和功率谱密度的脑电信号分类

由于单一域缺少其他相关信息而导致运动想象分类准确率不高和泛用性差,本文研究设计了基于空间域和频域的运动想象分类方法。根据运动想象执行时的对侧映射机制以及事件相关同步和事件相关去同步的现象,对C3和C4通道数据进行共空间模式和功率谱密度特征提取和融合,然后使用网格搜索参数优化的支持向量机对运动想象的脑电信号进行分类。结果表明共空间模式和功率谱密度的融合特征,解决了共空间模式对噪声敏感以及缺少频率特征信息的缺点,实现了更高的分类结果和泛化性,分类准确率达91.3%,验证了该方法的有效性。     

Data Location Mechanism in Agent-Based Autonomic Storage Systems

This paper introduces agent-based methodology to build a distributed autonomic storage system infrastructure, and an effectively negotiation mechanism based on agent is applied for data location. We present Availability-based Data Allocation （ADA） algorithm as a data placement strategy to achieve high efficient utilization of storage resources by employing multiple distributed storage resources. We use Bloom filter in each storage device to track the location of data. We present the data lookup strategy that small size of read request is handled directly, and large size of read request is handled by cooperation with storage devices.The performance evaluation shows that the data location mechanism is high available and can work well for heterogeneous autonomic storage systems.     

Watching cartoons activates the medial prefrontal cortex in children

The medial prefrontal cortex (MPFC) of human adults is involved in attributing mental states to real human agents but not to virtual artificial characters. This study examined whether such differential MPFC activity can be observed in children who are more fascinated by cartoons than adults. We measured brain activity using functional magnetic resonance imaging (fMRI) while 10-year-old children watched movie and cartoon clips, simulating real and virtual visual worlds, respectively. We showed neuroimaging evidence that, in contrast to adults, the MPFC of children was activated when perceiving both human agents and artificial characters in coherent visual events. Our findings suggest that, around the age of 10 years, the MPFC activity in children is different from that in adults in that it can be spontaneously activated by non-human agents in a virtual visual world.     

Meteorological observations on Mount Everest in 2005

Mount Everest,the highest point on the Earth is often referred to as the earth's third pole as such the place is relatively inaccessible and little is known about its meteorology.In April 2005,an automatic weather station was installed at the mountain's North Col(6523 m a.s.l.).According to the observational 10-minute mean and daily records,the meteorological characteristics were analyzed. All the meteorological elements displayed obvious diurnal variations during May 1 to July 22,2005.The monthly variation of daily meteo- rological elements on Mount Everest coincided with that on Dingri,the closest routine meteorological station,with the high correlation co- efficients of 0.928,0.877,0.682,0.755,0.826 and 0.676(n=83,p<0.001)for mean temperature,minimum temperature,max- imum temperature,relative humidity,pressure and wind speed,respectively.Furthermore,the vertical mean gradient of temperature was above 0.6℃/100 m,especially for the daily maximum temperature.Most weather events on Mount Everest prominently appeared on the same day as those on Dingri,especially those from daily mean pressure,temperature and relative humidity with the cross-correlation coeffi- cients of 0.673,0.485 and 0.487(n=83,p<0.001),respectively.Some other weather events on Mount Everest lagged one-day be- hind those on Dingri.Furthermore,forecasting of the weather events on Mount Everest from pressure on Dingri was more reliable than those from the other meteorological elements.The conclusions are much important for research on meteorology and climate changes in the region.     

多元化企业核心业务的选择与评价方法

针对企业如何选择与评价多元化企业核心业务,提出了一种操作性更好的分析方法·该方法基于母合优势理论,分别通过分析评价母体特征与业务的成功关键因素的匹配程度以及与业务母合机会的匹配程度两种匹配性因素,建立了选择与评价多元化企业核心业务的数量模型·最后,通过一个实例说明了如何运用该模型进行多元化企业核心业务的选择和评价·     

CFD simulation of fluidization quality in the three-dimensional fluidized bed

Multiphase computational fluid dynamics （CFD） has become an alternative method to experimental investigation for predicting the fluid dynamics in gas-solid fluidized beds. The model of Brandani and Zhang, which contains additional terms in both the gas- and solidphase momentum equations, is employed to explore homogeneous fluidization of Geldart type A particles and bubbling fluidization of Geldart type B particles in three-dimensional gas-fluidized beds. In this model, only a correlation for drag force is necessary to close the governing equations. Two kinds of solids, i.e., fine alumina powder （dp= 60 μm and pp = 1500 kg/m^3） and sand （dp = 610 μm and pp = 2500 kg/m^3）, are numerically simulated in a rectangular duct of 0.2 m （long） × 0.2 m （wide）× 0.5 m （high） size. The results show good agreement with the classic theory of Geldart.     

Millennial- and orbital-scale changes in the East Asian monsoon over the past 224,000 years

High-resolution speleothem records from China have provided insights into the factors that control the strength of the East Asian monsoon. Our understanding of these factors remains incomplete, however, owing to gaps in the record of monsoon history over the past two interglacial-glacial cycles. In particular, missing sections have hampered our ability to test ideas about orbital-scale controls on the monsoon, the causes of millennial-scale events and relationships between changes in the monsoon and climate in other regions. Here we present an absolute-dated oxygen isotope record from Sanbao cave, central China, that completes a Chinese-cave-based record of the strength of the East Asian monsoon that covers the past 224,000 years. The record is dominated by 23,000-year-long cycles that are synchronous within dating errors with summer insolation at 65 degrees N (ref. 10), supporting the idea that tropical/subtropical monsoons respond dominantly and directly to changes in Northern Hemisphere summer insolation on orbital timescales. The cycles are punctuated by millennial-scale strong-summer-monsoon events (Chinese interstadials), and the new record allows us to identify the complete series of these events over the past two interglacial-glacial cycles. Their duration decreases and their frequency increases during glacial build-up in both the last and penultimate glacial periods, indicating that ice sheet size affects their character and pacing. The ages of the events are exceptionally well constrained and may thus serve as benchmarks for correlating and calibrating climate records.