不同碱度精炼渣系对弹簧钢夹杂物的影响

大颗粒不变形夹杂物是造成弹簧钢疲劳失效的主要原因。为了优化高级别弹簧钢55SiCr中夹杂物的组成、形态与分布,采用两次LF炉进站精炼方式,并在二次精炼过程中设计了两种不同碱度的渣系,通过氧氮分析仪、电子探针等检测手段对比分析两种工艺下钢中全氧含量、夹杂物尺寸与成分。结果表明,低碱度精炼渣使弹簧钢夹杂物成分趋近于Al2O3-SiO2-CaO系统中低熔点塑性化区间,但不利于大颗粒夹杂物的控制与消除;高碱度精炼渣使夹杂物的平均尺寸更小,分布更均匀,但夹杂物中Al2O3含量偏高;高碱度精炼渣有利于钢液的深脱氧,钢的洁净度更高,但需注意连铸过程中钢液的氧化。     

作为功能材料的矶松素的提取及HMO计算

对从植物中提取的矶松素的大π电子体系进行ＨＭＯ计算．计算表明：矶松素可能具有较大的二阶极化率和可能存在双稳态结构,是分子电子器件和非线性光学（ＮＬＯ）器件的理想化学材料     

巯基交联淀粉的制备及其对汞等重金属离子絮凝性能的研究

交联玉米淀粉与巯基乙酸在酸催化下,以THF为反应介质,在适当的配料比和反应条件下,可以制得巯基含量为0.5～0.8mmol/g的巯基交联淀粉。对一些重金属,它是一种有效的絮凝剂,可用于含汞、铅和镉等废水的处理。     

西天目山土壤线虫区系与生态的初步探讨

1987年5月由中国自然科学基金会资助,开始了“亚热带森林土壤动物区系及其在森林生态平衡中的作用”的研究工作,开选定浙江西天目山作为研究点之一。本工作在西天目山选定5个采样区。经鉴定,西天目山土壤线虫可分5目23属40种,其中有13种仅鉴定到属,并认为,土壤线虫数量的变化,主要与海拔高度、温度、土壤pH值、降水量等因素有关。     

Effect of thrombin on the apoptosis of hippocampal neurons in vitro

Hippocampal neurons were treated by thrombin and thrombin receptor activating peptides (TRAP). Cell survival rate was decreased in a dose-dependent manner by MTT assay. The numbers of apoptotic cell and apoptotic rate of hippocampal neurons treated by different concentrations of thrombin were increased in a dose-dependent manner by terminal deoxynucleotidyl transferase (TdT) mediated dUTP-biotin nick end-labeling (TUNEL) method and Flow Cytometry. When the concentration of thrombin is 40 U/mL, TUNEL positive cells and apoptotic rate of hippocampal neurons reached peak value, were 27.3±4.0 and (29.333±4.633)%, respectively. Immunocytochemistry assay show that Bcl-2 protein expression was down-regulated and Bax protein expression was up-regulated with the concentration of thrombin increased. TRAP can mimic the effect of thrombin to induce apoptosis on hippocampal neurons. These data demonstrated that thrombin induced hippocampal neuron apoptosis in a dose-dependent manner through activating protease-activated protein-1 (PAR-1). The change in expression of Bcl-2 and Bax was related with the effect of high concentration thrombin induced apoptosis on hippocampal neurons. Foundation item: Supported by the Natural Science Foundation of Hainan Province (N30215) Biography: YANG Wen-qiong (1968-), female, Ph.D. candidate, research direction: cerebrovascular disease.     

Study on control strategy of CAN bus network based on event triggered mode

In order to reduce the load rate of CAN bus and improve the real-time performance of control system, CAN bus control system of a pure electric vehicle is studied. Communication messages of each node are optimized and redefined by sorting the message into three types: control message, status message and alarm message. Event triggered mode is added to the communication way of CAN bus, and the communication control strategy of the vehicle is made. It is proved that CAN bus load rate of control system is reduced after optimization, and the real-time performance of communication is improved effectively.     

Simon算法对SIMON密码的密钥恢复攻击

近年来,随着量子技术被应用到密码算法的安全性分析中,经典密码算法的安全性受到了极大的威胁.将Simon量子算法应用到SIMON密码的分析之中,成功构造一个周期函数,将3轮SIMON密码与随机置换区分开.随后对该周期函数满足Simon问题条件的参数进行估计,找到且证明其存在一个上界,从而计算出SIMON32/48/64这3类密码对应参数的上界值.最后通过分别构造加密和解密过程相应的区分器,对6轮SIMON密码进行了密钥恢复攻击,得到了4个轮密钥,并给出了该攻击的时间复杂度.     

维格纳分布中交叉项干扰及平滑消除方法

结合心电信号的数学模型讨论维格纳分布的交叉项干扰以及运用平滑处理消除该干扰的原理，进而探讨选择两维高窗参数的方法，模拟信号和实验的心肌缺血家兔心电信号的分析结果证实，平滑维格纳分布既可克服交叉又项干扰，又能满足心电信号分析对时间分辨率和频率分辨率的要求。     

液氮在弦月形通道中沸腾传热强化实验研究

首次利用极限偏心圆管形成的弦月形通道在液氮池中进行了两相流沸腾传热实验研究，实验结果表明，当热流密度达到９ｋＷ／ｍ＾２时，弦月形通道内的传热温差仅为１．１Ｋ，传热性能达到了目前一致公认的沸腾传热系数最高的烧结多孔表面管的同等水平，而其制造工艺、生产成本和运行操作等方面却大大优于后者。     

动态应力下功率n-LDMOS器件热载流子退化恢复效应

针对功率n-LDMOS器件在动态应力条件下的热载流子退化恢复效应进行了实验和理论研究.电荷泵实验测试和器件专用计算机辅助软件的仿真分析结果表明,在施加不同的动态应力条件下,功率n-LDMOS器件存在2种主要的热载流子退化机理,即鸟嘴区域的热空穴注入和沟道区域的界面态产生,均有明显的退化恢复效应.对功率n-LDMOS器件施加2个连续3 600 s的不同应力,观察每个阶段结束时刻的CP电流曲线,发现该器件在应力变换期间确实发生了热空穴的退陷阱效应.然后,对功率n-LDMOS器件施加3个连续3 600 s的不同应力,观察每个阶段结束时刻的CP电流曲线,发现器件处于关断阶段时,已产生的界面态存在一定程度的复合.