BEPCⅡ-LINAC试验束第二靶室混合辐射环境模拟

 为提供探测器或样品辐照实验与靶物质选择所需的辐射环境基本物理参数,利用蒙特卡罗模拟软件FLUKA对BEPCⅡ-LINAC试验束E2线上的第二靶室混合辐射环境进行了模拟计算,得到了以靶心为圆心,半径为1 m的球面上的各次级粒子的微分通量、角度微分截面、磁谱仪方位角上的双微分能谱、靶室内的剂量率分布。     

旋转相似载荷下轴对称结构弹性响应的快速算法:旋转叠加法及其应用

基于叠加原理,采用坐标旋转和线性叠加的方法,建立了求解旋转相似载荷下轴对称结构弹性响应的快速算法--旋转叠加法.文章首先给出了"旋转相似载荷"的定义,推导了相关计算公式,然后给出了一个应用实例,验证了算法的正确性和有效性,最后对相关问题进行了讨论.旋转叠加法巧妙利用了叠加原理和结构的轴对称性,对同一结构只需一次分析,即...     

铝型材电泳涂装小试工艺中影响漆膜质量的几个因素的研究

研究了实验室小试条件下电压、时间、极距等因素对铝型材阳极电泳涂膜厚度及膜层外观的影响,确定了电泳涂装的较佳工艺:电压130 V,时间130～230 s,极距88～110 mm,室温下进行.在此条件下的电泳涂膜厚度可达21 μm以上,合乎工艺的生产要求.且各项耐蚀性检测结果较好.     

由一道考题引发的探究

1．考题呈现 近日一次高三模拟考中有如下考题： 已知抛物线y2=4x上有一点A（1,2）,过点A作抛物线的两条动弦AB和AC,且AB垂直AC,问：直线BC是否过定点？若过定点,求出该定点;若不过,请说明理由．     

中美高中理科物理主流教材中阅读材料的比较与启示

分析了中美高中理科物理主流教材在阅读材料上的差异,并得到了启示,以便更好地为教师开展阅读材料的教学提供参考.     

Nonlinear dynamics analysis of cluster-shaped conservative flows generated from a generalized thermostatted system

The thermostatted system is a conservative system different from Hamiltonian systems,and has attracted much attention because of its rich and different nonlinear dynamics.We report and analyze the multiple equilibria and curve axes of the cluster-shaped conservative flows generated from a generalized thermostatted system.It is found that the cluster-shaped structure is reflected in the geometry of the Hamiltonian,such as isosurfaces and local centers,and the shapes of cluster-shaped chaotic flows and invariant tori rely on the isosurfaces determined by initial conditions,while the numbers of clusters are subject to the local centers solved by the Hessian matrix of the Hamiltonian.Moreover,the study shows that the cluster-shaped chaotic flows and invariant tori are chained together by curve axes,which are the segments of equilibrium curves of the generalized thermostatted system.Furthermore,the interesting results are vividly demonstrated by the numerical simulations.     

Wildly Tunable,High-Efficiency MgO：PPLN Mid-IR Optical Parametric Oscillator Pumped by a Yb-Fiber Laser

We demonstrate a wildly tunable, high-eFficiency mid-infrared （mid-IR） output-coupled single resonant optical parametric oscillator （OC-SRO） pumped by a Yb-fiber laser. The compact mid-infrared source employs a 50- mm-long, multi-grating MgO-doped periodically poled lithium niobate （MgO-PPLN） crystal, providing as much as 1.73 W idler power at 3.012#m, and 1.27W signal power at 1645nm, corresponding to an overall conversion efficiency of 41.7% and a slope efficiency of 77.9%. In particular, the mid-infrared output power of 1.03 W and 0.67W are obtained at 3.7μm and 3.9μm, respectively, with an optical-to-optical conversion efficiency of 14.3% and 9.3%. Furthermore, the idler light is tunable from 3 μm to 3.9 μm by changing the periods from 31 to 28.5μm, with the output power 〉1 W over 78% of the tuning range. Our experimental results are pump power limited and further mid-IR power and conversion efficiency could be obtained with a suitable high-power pump source. The total OC-SRO output power rms at 2.6 W is about 0.6% during 2 h measurement.     

Comparative Studies on Two 1,8-Naphthalimide Derivatives with Experimental and Theoretical Methods

Two 1,8-naphthalimide derivatives of 7H-benzimidazo[2,1,-a]benz[de] isoquino- lin-7-one（1） and 4-bromo-7H-benzimidazo[2,1,-a]benz[de]isoquinolin-7-one（2） have been synthesized and characterized by elemental analysis, IR, 1H NMR, UV-Vis and fluorescence spectra. For the two compounds, density functional theory（DFT） calculations of the structures and natural population atomic charge analysis have been performed at the B3LYP/6-311G＊＊ level of theory. Based on Onsager reaction filed model and by using TD-DFT method at the B3LYP/6-311G＊＊ level, electron spectra of 1 and 2 with solvent effect in CHCl3 solvent have been predicted, which are in agreement with the experimental ones. Comparative studies on 1 and 2 indicate that introducing an electron-withdrawing group of Br into the 4-position of naphthalene ring in 2 does not significantly make the molecular geometry of 2 different from that of 1, but evidently changes the atomic charge redistribution, moves the positive-negative charges center and then changes the dipole moment in 2. Additionally, for compound 2, the existence of Br atom has also influenced the peak intensity and peak locations in both electron and fluorescence spectra.     

适用于TATB,RDX,HMX含能材料的全原子力场的建立与验证

报道一个适用于三种常见的含能材料分子三硝基三氨基苯(TATB),环三亚甲基三硝胺(RDX),环四亚甲基四硝胺(HMX)的全原子力场.力场采用广泛使用的力场函数形式,其中键参数通过拟合量子化学密度泛函计算的数据获得,电荷参数和范德华参数通过拟合相应的分子晶体的物理性质(密度和升华焓)优化得到.通过计算分子和分子晶体的性质显示该力场可以用来准确地预测分子结构、分子振动频率和分子晶体的晶胞参数、密度和升华焓.进一步的验证显示该力场可用来较为准确地预测分子晶体的状态方程和机械模量.     

新型高分子季鏻盐改性抗菌塑料的制备及性能研究

高分子季鏻盐抗菌剂具有安全、高效的特点,使用过程中不会通过皮肤组织进行渗透。本文将实验室自制的新型高分子季鏻盐抗菌剂粉末与低密度聚乙烯(LDPE)基体材料共混,通过熔融挤出法制备了含梯度浓度抗菌剂的抗菌塑料,研究了不同抗菌剂添加浓度对基体材料熔融性质及其抗菌性能的影响,并探讨了抗菌塑料的生物安全性。结果表明,梯度浓度的抗菌剂改性塑料对金黄色葡萄球菌和大肠杆菌均有良好的抗菌效果;生物安全性测试结果表明,抗菌塑料的细胞毒性为0级,说明抗菌塑料具有较高的生物安全性。