Effect of heat treatment on magnetostriction and order-disorder transition of Fe83Ga17

Effect of heat treatment on magnetostrictive properties and order-disorder transition of 〈110〉-oriented polycrystal Fe83Ga17 alloys is investigated. It is found that magnetostriction and order degree of Fe83Ga17 alloys are very sensitive to cooling rate. Variation of magnetostriction is discussed in terms of order-disorder transition. Under compressive stress of 20 Mpa, saturation strain λs of partially ordered Fe83Ga17 alloys quenched into water reaches 298×10-6.     

分布式被动传感器网异步采样下的机动目标跟踪

针对分布式被动传感器网的特点，提出了一种异步采样条件下机动目标跟踪方法。该方法采用交互式多模型概率数据互联滤波器跟踪机动目标。为启动滤波器，采用最大似然法估计目标初始状态；为适应异步观测条件，提出了马尔可夫转移概率计算方法。仿真实验表明，在分布式被动传感器网中采用该算法能有效进行机动目标跟踪。     

Hypoosmotic shock induces a stateⅠtransition of photosynthetic apparatus in Dunaliella salina

The effects of hypoosmotic shock on state transition in darkness in Dunaliella salina were studied. When the concentration of NaCI in culture medium was dropped from 1.5 to 0.5 mol/L abruptly, the photosynthetic rate of D.salina declined, but the respiratory rate and intracellular ATP content increased in the dark. The FpsⅡ/FpsⅠ ratio at 77 K of D. salina cells exposed to hypoosmotic shock was higher than that of control cells, indicating that more excitation energy was distributed to PS Ⅱ in stressed D.salina cells upon illumination. A decrease in LHC Ⅱ phosphorylation level was also observed when D.salina was exposed to hypoosmotic shock. Thus a state Ⅰ transition of photosynthetic apparatus occurs when D.salina suffers hypoosmotic shock in darkness, which is supposed to be related to an enhancement of respiration and an increase in ATP content in stressed D.salina cells.     

平图的transition多项式的Maple计算

将现有的计算方法改进得到了一种新的计算平图的transition多项式的方法。算法使用了圈置换的方法计算每个transition操作所产生的欧拉圈的数目。利用Maple软件编写出了该算法的程序,通过这个程序,可以实现任意一个平图的transition多项式的计算。     

超高速碰撞成坑特性分子动力学模拟

基于开源分子动力学程序LAMMPS,对直径为4.86 nm的球形铝弹丸以10 km/s超高速撞击半无限厚铝靶进行模拟.弹坑形成的物理过程与超高速碰撞宏观现象相似,弹坑深度与宏观经验公式计算结果基本一致,获得了弹丸头部相对于碰撞点的位移随时间的变化规律;分析了靶板中冲击波传播特性,碰撞初期冲击波阵面传播速度达到12 km/s,随后冲击波传播速度逐渐减小,接近于弹性波速;弹坑周围观测区发生熔化相变,熔化时间持续0.07 ps,熔化层厚度为2.9 nm;弹坑周围观测区冷却速率达到1015 K/s量级,抑制了原子重结晶,最终呈现为固相非晶结构.      

The hidden disintegration of cluster heterogeneity in Fe-based glass-forming alloy melt

The evolution of liquid metal at high temperature is known much less than their solid states. This is partially due to that the message concerning clusters, metastable phase or heterogeneity in liquid is usually too slight to be traced. Here, we shed some light on the nature of structural evolution of Fe-based glass-forming alloy during overheating process by the investigation of high-temperature melt viscometry and first principles simulations. It was found that a structural transition around 1400 ℃ occurred in the melts of initial homogeneous ingot, heterogeneous ingot and amorphous ribbons jointly, and was confirmed by the results from differential scanning calorimeter(DSC), and ab initio molecular dynamics(AIMD). Combining these results with Fe-Si-B ternary phase diagram and the melting characteristics of Fe-B compounds, it is safe to conclude that the disintegration of Fe_2B type clusters to Fe_3B-type clusters leads to the observed transition. These results offer a significant reference for the preparation and property control of Fe-based amorphous alloys.     

数学教育中几个关键词的定界、作用及教学对策

文中就目前数学教育中出现的一些被弱化的领域,以关键词的形式分别给出其定界、作用及教学对策。     

双水作用Met过渡态电子激发特性的图解分析

采用密度泛函理论(DFT)中的B3 LYP方法,在6-311+G(2df)基组水平上优化气相条件下甲硫氨酸(Met)分子的几何构型,分析Met+2 H 2 O分子体系手性转变过程中各基元反应物的特征,并在M06-2X/def2-TZVP下,用含时密度泛函理论(TDDFT)方法给出隐式溶剂甲醇下Met+2 H2 O分子体...     

磁场影响水溶液冰晶的试验及装置

为寻找生物组织低温无损保存的新方法,研究了磁场对KMnO4溶液冰晶形成的影响.建立了不同形式的磁场发生装置,包括旋转磁场、方波叠加正弦波磁场、50kHz磁场.为保证样品降温过程慢速均匀,运用虚拟仪器技术建立了温度测控系统.使用低温显微系统对磁场影响下样品冰晶的形态进行了记录.结果表明,低频旋转磁场对生物溶液冰晶的形成产生了影响,尤其50kHz交变磁场对溶液中冰晶的生长具有较为显著的抑制作用,说明在易于产生的低冷冻速率下,交变磁场对生物组织的低温无损保存研究具有重要意义,适合实际应用.     

基于数量柔性契约与Markov链的应急物资采购模型

突发灾害是以一定概率发生的随机事件,其状态总是不断发生转移,使政府已采购的应急物资在状态好转时易造成浪费,在状态持续恶化时难以满足突发需求,因此考虑突发灾害状态转移的应急物资采购策略对提升政府应急物资保障能力至关重要.本文将突发灾害状态转移过程视为一个有限次的齐次Markov链,构建了基于数量柔性契约的应急物资采购模型,分析了政企达成合作的条件与双方最优决策策略.采用数值计算与敏感性分析验证该模型的有效性,讨论了若干外生变量对政企最优决策策略与双方成本收益的影响,提出了重要的管理启示.结果表明,突发灾害状态转移情形下的应急物资采购模型既能提高政府应急物资保障能力,又可以保障企业合理收益与控制政府成本.