Early effects of low dose C ion or X-ray irradiation on human peripheral blood lymphocytes

The aim of this study was to estimate the acute effects of low dose ¹²C⁶⁺ ions or X-ray radiation on human immune function. The human peripheral blood lymphocytes (HPBL) of seven healthy donors were exposed to 0.05 Gy ¹²C⁶⁺ ions or X-ray radiation and cell responses were measured at 24 h after exposure. The cytotoxic activities of HPBL were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT); the percentages of T and NK cells subsets were detected by flow cytometry; mRNA expression of interleukin (IL)-2, tumor necrosis factor (TNF)-α and interferon (IFN)-γ were examined by real time quantitative RT-PCR (qRT-PCR); and these cytokines protein levels in supernatant of cultured cells were assayed by enzyme-linked immunosorbent assays (ELISA). The results showed that the cytotoxic activity of HPBL, mRNA expression of IL-2, IFN-γ and TNF-α in HPBL and their protein levels in supernatant were significantly increased at 24 h after exposure to 0.05 Gy ¹²C⁶⁺ ions radiation and the effects were stronger than observed for X-ray exposure. However, there was no significant change in the percentage of T and NK cells subsets of HPBL. These results suggested that 0.05 Gy high linear energy transfer (LET) ¹²C⁶⁺ radiation was a more effective approach to host immune enhancement than that of low LET X-ray. We conclude that cytokines production might be used as sensitive indicators of acute response to LDI.     

Magnetic Field Fluctuations in the Solar Wind, Foreshock and Magnetosheath： Cluster Data Analysis

46 magnetosheath crossing events from the two years (2001.2-2003.1) of Cluster magnetic field measurements are identified and used to investigate the characters of the magnetic field fluctuations in the regions of undisturbed solar wind, foreshock, magnetosheath. The preliminary results indicate the properties of the plasma turbulence in the magnetosheath are strongly controlled by IMF orientation with respect to the bow shock normal. The amplitude of the magnetic field magnitude and direction variations behind quasi-parallel bow shock are larger than those behind quasi-perpendicular bow shock. Almost purely compressional waves are found in quasi-perpendicular magnetosheath.     

基于动态ID的远程认证方案的改进

智能卡由于具有低功耗、安全计算和便携性的特点,常常被用做身份认证终端.基于静态口令的认证方案不能由用户选择密钥并且需要在服务器保存一个密钥表,而基于动态ID的方案能解决这些问题.提出了新的方案,指出Liao-Lee-Hwang方案中不能抗偷窃攻击的缺点,并在其基础上做了改进.新的改进方案不仅继承了原方案中抗猜测攻击、实现共同认证、服务器不会泄露用户密钥的的优点,同时也避免了窃取攻击;并且新的改进方案在计算量上也小于Liao-Lee-Hwang的方案.      

一种减少失速保护虚警率的混合滤波方法

针对飞机失速保护设计过程中易出现虚警的情况,提出一种基于FIR和传统滤波器相结合的混合滤波方法。结合飞机本体的运动特征,对参与失速保护逻辑运算的两个重要参数,即侧向加速度和迎角信号进行频率分析,基于信号的特征设计混合滤波器,然后采用Simulink滤波工具箱设计滤波器对信号进行滤波处理。仿真结果表明该方法能够减少虚警率的发生,特别是大背景噪声下的虚警率能够得到较好抑制,验证了滤波器设计正确性,从而提高失速保护功能对适航条款符合性。该滤波器设计方法,不但可以有效解决本文提到的问题,对于其他涉及信号处理的系统设计同样具有借鉴意义。     

Selective laser melting of Al–8.5Fe–1.3V–1.7Si alloy: Investigation on the resultant microstructure and hardness

This article presents the microstructure and hardness variation of an Al–8.5Fe–1.3V–1.7Si(wt%, FVS0812) alloy after selective laser melting(SLM) modification. Three zones were distinguished across the melting pool of the SLM-processed FVS0812 alloy: the laser melted zone(LMZ), the melting pool border, and the heat affected zone(HAZ) in the previously deposited area around the melting pool. Inside the LMZ, either an extremely fine cellular-dendritic structure or a mixture zone of the a-Al matrix and nanoscale Al_(12)(Fe,V)_3Si particles appeared. With a decreased laser beam scanning speed, the cellular-dendritic structure zone within the LMZ shrank significantly while the mixture zone expanded. The a-Al and Al_(12)(Fe,V)_3Si mixture zone was also observed in the HAZ, but another phase, submicron h-Al_(13)Fe_4 particles with rectangular or hexagonal shapes,formed along the melting pool border. Microhardness tests indicated that the hardness of the SLM-processed FVS0812 samples far exceeded that of the as-cast FVS0812 alloy.     

二元双喉道射流推力矢量喷管流动参数影响的数值研究

采用数值模拟方法研究了不同流动参数对二元双喉道射流推力矢量喷管(Dual-throat fluidic Thrust-vectoring Nozzle,DTN)内流特性和推力矢量控制效果的影响。结果表明,DTN在非推力矢量情况下,NPR在3~4范围时,推力系数较大,达到0.968,而流量系数较小,仅为0.93;NPR再增大,推力系数迅速下降。在推力矢量情况下,落压比一定时,随着次流流量比的增加,推力矢量角增加,而流量系数、推力系数、推力矢量效率减小;次流流量比一定时,随着落压比的增加,推力矢量角减小,系统推力系数先增加后减小,流量系数略微增加。     

半捷联位标器稳定跟踪与弹体姿态一体化控制

半捷联位标器安装在弹体上,由于寄生回路的存在,使得位标器稳定跟踪控制回路和弹体姿态控制回路产生严重耦合,影响了位标器的稳定与跟踪。针对半捷联导引头稳定平台的稳定与跟踪问题,提出了一种半捷联位标器稳定跟踪控制与弹体姿态控制的一体化方法。基于反步控制原理设计了控制律,通过合理选择反馈增益可保证系统的稳定性与动态性能。最后对一体化设计与传统分离设计进行了仿真对比。仿真结果表明：考虑位标器稳定跟踪回路与导弹姿态回路耦合的一体化控制器,不仅能够保证弹体姿态控制系统快速响应,还可以提高位标器的稳定跟踪性能,并降低位标器跟踪不上高速目标的可能性。     

种层厚度对油麦兼用集排器供种装置充种性能的影响

为研究种层厚度对油麦兼用集排器供种装置充种性能的影响,该文运用EDEM(engineering discrete element method)软件和高速摄像技术,对不同种层调节板倾角和种层厚度的种群运动与供种性能进行了仿真与试验研究。EDEM仿真分析了种层厚度与转速对种群压力、种群与供种机构切向力和充种数量的影响;台架试验研究了种层厚度对充填角和供种性能的影响。结果表明:倾角为60°种层调节板的种群压力较大,充填角和充种性能均较优;种群压力和切向力随纵向距离增加而增加,随横向距离增加而降低;随转速增加,种群压力趋于稳定,切向力随之增加,单个型孔充种数量降低5%。转速为10～50 r/min时,初始充填角、充填角和供种速率均随纵向距离增加和横向距离降低而增加,但充种数量变异系数呈先降后升的趋势。种群压力、切向力、初始充填角、充填角与供种速率均呈极显著正相关,种群压力和切向力与初始充填角和充填角均呈极显著正相关,种层厚度和转速影响充填角分别源于种群压力和切向力。在纵向距离分别为15和20 mm,横向距离为46 mm条件下,油菜、小麦供种速率变异系数和破损率分别均低于1.0%和0.1%。田间试验表明该优化种层厚度条件下的集排器油菜种植密度满足农艺种植要求。该研究明确了种层厚度影响油麦兼用集排器供种装置充种性能的原因,为油麦兼用集排器供种装置种层厚度调节和结构改进提供了参考。     

Distributed state estimation for heterogeneous mobile sensor networks with stochastic observation loss

The problem of distributed fusion and random observation loss for mobile sensor networks is investigated herein. In view of the fact that the measured values, sampling frequency and noise of various sensors are different, the observation model of a heterogeneous network is constructed. A binary random variable is introduced to describe the drop of observation component and the topology switching problem caused by complete observation loss is also considered. A cubature information filtering algo...