A Study on SSVEP-Based BCI

Abstract-Brain-computer interface （BCI） can help the deformity person finish some basic activities. In this paper, we concern some critical aspects of SSVEP based BCI, including stimulator selection, method of SSVEP extracting in a short time, stimulating frequency selection, and signal electrode selection. The conclusion is that the stimulator type should be based on the complexity of the BCI system, the method based on wavelet analysis is more valid than the power spectrum method in extracting the SSVEP in a short period, and the selections of stimulating frequency and electrode are important in designing a BCI system. These contents are meaningful for implementing a real SSVEP-based BCI.     

Chinese yam polysaccharide enhances growth performance and cellular immune response in weanling rats

BACKGROUND: In order to develop a novel dietary additive for potential application in domestic animals and humans, a fraction of Chinese yam polysaccharide (CYP) was prepared and a study was conducted to determine the effects of dietary supplementation with CYP on the immune response and growth performance in weanling rats. RESULTS: Dietary supplementation with CYP increased the average daily feed intake and average daily gain but decreased the feed/gain ratio overall compared with the non‐supplemented group. CYP also significantly increased the serum contents of interleukin‐2 and tumour necrosis factor and the proliferation activity of peripheral lymphocytes but decreased the serum contents of low‐density lipoprotein, total cholesterol and triglyceride compared with the non‐supplemented group. CONCLUSION: The increase in cellular immunity in CYP‐supplemented weanling rats confers an important protective role in the non‐specific defence against infections. This herbal polysaccharide, as a natural green dietary additive for promoting the immune response and healthy growth, may offer an effective alternative to antibiotics for weanling animals. Copyright © 2009 Society of Chemical Industry     

单颗磨粒划擦SiCf/SiC陶瓷基复合材料的试验研究

为研究SiC纤维(SiC_f)增强SiC陶瓷基复合材料(SiC_f/SiC)的磨削损伤机理,搭建试验平台开展单颗磨粒划擦试验,测量划擦力并观察其表面损伤形式,研究磨粒形状、划痕深度和SiC_f取向对复合材料磨削机理的影响。试验结果表明:SiC_f/SiC陶瓷基复合材料的划擦损伤形式主要有基体崩碎、纤维裂纹、断裂和拔出等。在SiC_f/SiC陶瓷基复合材料划擦过程中,尖锐状磨粒的划擦力更小,且整条划痕的表面损伤范围较扁平状磨粒的小。用扁平状磨粒划擦但纤维取向γ= 0°时,划痕形貌中纤维断裂、纤维拔出等损伤形式出现较少。      

选区激光熔化Inconel 718合金的熔池形态与组织

通过不同扫描速度和扫描方式的选区激光熔化(SLM)技术制备了Inconel 718合金,研究了工艺参数对熔池的形态、凝固组织、晶粒大小和晶粒取向的影响。结果表明,随着扫描速度增加,熔池的深度与宽度的比值增大,曲率增大;而扫描速度为1 450mm/s时,采用单向扫描比十字交叉扫描时深宽比值更大。在熔池内,凝固组织由熔池底部的胞晶向熔池侧面的胞枝晶转变。晶粒以<001>方向择优生长,其晶粒间的取向差角以小角度(<15°)为主。当十字交叉扫描时,随着扫描速度增加,小角度取向差角的分布分数增加。当速度一定、采用十字交叉扫描时,小角度的取向差角占比为62.57%,而采用单向扫描时为47.69%。     

深冷处理对YG8硬质合金/42CrMo钢钎焊接头残余应力的影响

通过ANSYS仿真软件建立了YG8硬质合金/42CrMo钢钎焊接头的焊接工艺模型和深冷处理工艺模型,分析了接头表面残余应力分布,并与经深冷+回火处理后的焊接接头表面残余应力进行对比。结果表明,深冷处理可使焊接接头42CrMo钢侧形成残余压应力,且深冷温度对残余压应力的影响较深冷次数更明显。最优深冷工艺为-160 ℃深冷3次,且仿真结果与试验测量值相差不大,表明所建立的模型具有一定的可靠性。     

Impacts of test factors on heavy ion single event multiple-cell upsets in nanometer-scale SRAM

Single event multiple-cell upsets (MCU) increase sharply with the semiconductor devices scaling. The impacts of several test factors on heavy ion single event MCU in 65 nm SRAM are studied based on the buildup of MCU test data acquiring and processing technique, including the heavy ion LET, the tilt angle, the device orientation, the test pattern and the supply voltage; the MCU physical bitmaps are extracted correspondingly. The dependencies of parameters such as the MCU percentage, MCU mean and topological pattern on these factors are summarized and analyzed. This work is meaningful for developing a more reasonable single event test method and assessing the effectiveness of anti-MCU strategies on nanometer-scale devices.     

基于FPGA的电机伺服器设计

文中针对传统的8位单片机由于计算功能等条件限制和系统内部体系结构,在实现各种高效的控制算法和先进的电机控制理论时面临的着成本高,系统复杂程度高等问题.该设计采用模糊比例算法,即在大范围内采用模糊控制,以提高系统的动态响应速度,建立系统模型.通过现场可编程门阵列FPGA的数字电子系统对电机进行控制,以硬件电路算法实现算法程序,将原来的电路板级产品集成为芯片级产品,为电动机数字控制提供了一种新的有效方法.该设计的优点:低功耗,可靠性高,低成本.     

Fe_2O_3含量对MnZn铁氧体中Fe~(2+)量、磁性能及导电机制的影响

通过测量MnZn铁氧体的磁性能及Fe2+、Mn3+含量,考察了MnZn铁氧体中的Fe2+含量与配方中Fe2O3、MnO含量的关系及其对MnZn铁氧体磁性能的影响,并探究了MnZn铁氧体的导电机制。结果表明:随着(Fe2O3)a(MnO)b(ZnO)c主组成配方中a值递增(52.55≤a≤53.35)、b值递减(38.33≥b≥37.52),呈现出Fe2+、Mn3+含量均增加的趋势。随着Fe2+含量增加,Pcv谷底温度向低温方向移动,Pcv(min)先减后增,Pcv(20/70/100℃)均先减后增,均在Fe2+含量=1.55%附近达到最小值;起始磁导率μi(20/70/100℃)均先增后减。根据Pcv-Fe2+含量和μi-Fe2+含量两个关系图在Fe2O3=53.15mol%附近出现极值点这一现象,初步推测铁氧体Znα2+Mnβ-x2+Mnx3+Fey2+Feχ-y3+O4+σ(0.1794≥α≥0.1786,0.754≥β≥0.734,0.0031≤x≤0.0040,0.051≤y≤0.070)的导电机制为:y0.064时小极化子间的束缚能主导,y0.064时电子跃迁主导。     

考虑间歇性电源不确定性的配电网经济效益风险评估

主要针对风电波动对配电网造成的影响进行风险评估,建立了含储能、可控负荷的配电网风险评估模型,量化分析了配电网的风险损失,在风险评估中引入 VaR及 CVaR 等方法,为评估新能源并网风险提供了一种可行方法。仿真结果验证了模型的正确性和有效性,说明储能、可控负荷有助于降低配电网风险。     

锂离子电池SiO/C负极材料制备及电化学性能

以一氧化硅、葡萄糖以及AGP-8石墨为原料,通过行星球磨和后续的高温热解制备SiO/C复合负极材料。采用X射线衍射仪(XRD)和扫描电子显微镜(SEM)对其进行了表征,经较高温度热处理得到的复合物中含有单质硅材料。复合材料电极电化学测试显示,经1 350℃热处理得到复合材料循环38周后,容量保持率接近100%,这主要源于稳定的材料结构能够在一定程度上承受嵌/脱锂过程中硅体积的变化。