基于小波高频距离像的红外小目标检测

针对远距离复杂背景下红外小目标检测问题,本文提出了一种基于小波高频距离像的方法。该方法首先将处理空间变换到小波域,通过分析残留背景、目标和噪声系数在高频子带的差异,定义基于邻域均值的子带系数表达形式,构造高频子带系数的中心向量,对小波高频图像进行综合形成距离像,得到红外复杂背景的抑制结果。在此基础上,利用恒虚警率算法将单帧背景抑制图像分割成候选目标、残留背景和噪声像素点。最后,在时间域基于目标运动的相关性,利用管道滤波实现红外小目标的最终检测。仿真实验结果表明,相对于经典算法,本文方法可以实现对红外复杂背景的有效抑制,增强目标信号的强度,准确稳定的从红外复杂背景中检测出小目标。     

轫致辐射中电子束焦斑漂移现象的抑制

电子束焦斑偏离轴线中心的现象严重影响器件辐射效应实验的效率。介绍了一种简单有效的抑制电子束焦斑偏心的方法,研制了一种小尺寸不锈钢阴极,比较了不锈钢阴极和传统环形天鹅绒阴极在"强光一号"装置上的实验结果。实验结果表明对于小尺寸不锈钢阴极,最大辐射剂量位于靶面中心的概率为67%,位于35mm圆圈内的概率为100%。相比传统环形天鹅绒阴极(最大剂量落于中心位置的概率约20%,有60%以上概率偏离中心2~3cm)的实验统计数据,焦斑的偏心现象得到明显的抑制。     

超声法合成CePO4纳米线及发光性能研究

用CeO2作为铈源,采用可重复利用的H3PO4及非模板剂的情况下,用低温超声法成功合成了六方结构的CePO4一维纳米线材料。用X-射线粉末衍射(XRD)、透射电镜(TEM)和荧光分光光度计(FL)测试样品的物相结构、微观形貌、颗粒尺寸和发光性能;并研究超声时间和PO3-4/Ce3+摩尔比对产物的形貌和荧光性能的影响。结果表明:实验所做出的样品全部是六方晶系的结构,形貌都为一维纳米线,其纳米线长50~200nm,宽5~40nm左右;不同超声时间和PO3-4/Ce3+摩尔比的纳米线长径比不同,随超声时间的延长和PO3-4/Ce3+摩尔比增大纳米线出现团聚现象,产物在250~300nm处有宽的激发峰,在378nm处有一个发射峰,是属于Ce3+的5d-4f能级跃迁。     

不同防老剂对天然橡胶复合材料P-V-T关系的影响

采用PVT膨胀仪测试了添加不同防老剂的天然橡胶(NR)复合材料的压力-体积-温度(P-V-T)属性,通过最小二乘法拟合得到Tait方程参数,预测了体系的热膨胀系数(α)和等温压缩系数(β),结果表明,Tait状态方程可用来预测该复合材料体系的P-V-T行为,NR复合材料的α值随着压力的增大而减小,随温度变化不明显;β值随压力的增大而减小,且随着温度的升高而升高.分子模拟结果观察了体系凝聚态结构在不同温度下的变化,表明其变化原因是升温使体系自由体积增大,分子链的活动性增强,同时观察到单独加入防老剂4010NA或防老剂RD的体系α和β的值较大,说明其尺寸稳定性差,而当同时加入4010NA和RD进行防老剂并用时,体系的α和β值均较小,表明此复合材料体系不容易产生变形;通过分子动力学模拟手段计算了NR复合材料的内聚能密度(CED)随温度的变化规律,对于2种防老剂并用的体系,其CED比较大,说明分子间相互作用力较强,从而体系尺寸稳定性好,受温度和压力的影响小.     

不同品种环保橡胶填充油对乳聚丁苯橡胶性能影响研究

通过使用差示扫描量热仪(DSC)、橡胶加工分析仪(RPA)和动态压缩生热仪测试,分别研究了采用国内外不同品种的环保型橡胶填充油所制备的乳聚丁苯橡胶的热性能、动态力学性能以及动态压缩生热性能,并与非环保型丁苯橡胶SBR1712及环保型丁苯橡胶SBR1723进行了对比。结果表明,采用环保型芳烃油(TDAE)所制备的乳聚丁苯橡胶损耗因子最大,生热稍高于其它品种环保油;采用克拉玛依石化环保型环烷油(AP-10)所制备的乳聚丁苯橡胶动态压缩生热性能最好。     

Study of In Situ Formation of Magnesium Hydroxide Whisker via Basic Magnesium Chloride Whisker Regulated by Organic Parcels at Low Temperature

In this work, we demonstrate an in situ phase conversion from basic magnesium chloride（BMC） into magnesium hydroxide whisker by using polar organic solvent at low temperature. The morphology and phase composition of magnesium hydroxide whiskers prepared at different reaction temperature, alkali concentration and organic solvent were analyzed by X-ray diffraction（XRD） and scanning electronic microscope（SEM）. It was found that when one of the organic solvents such as absolute ethyl alcohol, butanol, polyethylene glycol（PEG-400）, acetone, et al. was selected as the template, the precursor BMC can transform into whisker-like magnesium hydroxide through precipitate transformation in low temperature and non-hydrothermal system. It can be reasonably explained that the regulation of Mg^2＋ solubility by those organic solvents and the sustained release of Mg^2＋ dissolution by organic adsorption played a significant role in the formation of magnesium hydroxide whisker via BMC whisker as the precursor.     

Vulcanization kinetics of graphene/styrene butadiene rubber nanocomposites

This paper presents the influence of graphene on the vulcanization kinetics of styrene butadiene rubber （SBR） with dicumyl peroxide. A curemeter and a differential scanning calorimeter were used to investigate the cure kinetics, from which the kinetic parameters and apparent activation energy were obtained. It turns out that with increasing graphene loading, the induction period of the vulcanization process of SBR is remarkably reduced at low graphene loading and then levels off; on the other hand, the optimum cure time shows a monotonous decrease. As a result, the vulcanization rate is suppressed at first and then accelerated, and the corresponding activation energy increases slightly at first and then decreases. Upon adding graphene, the crosslinking density of the nanocomposites increases, because graphene takes part in the vulcanization process.     

Three Zinc(Ⅱ) Complexes Based on 2-Carboxylic Acid-4-nitropyridine-1-oxide: Synthesis,Crystal Structure,and Fluorescence Properties

Three new metal-organic complexes, namely [Zn(POA)2(H2O)2](1), [Zn(POA)2(H2O)2]·2H2O(2) and [Zn(POA)2]n(3), have been synthesized by organic ligand 2-carboxylic acid-4-nitropyridine-1-oxide(POA) and zinc(Ⅱ) ions. The structures of complexes 1~3 are characterized by single-crystal X-ray analysis, XRD powder diffraction analysis, infrared spectroscopy and thermal stability analysis method. Complex 1 belongs to monoclinic system, space group C2/c with a = 22.8215(15), b = 7.5613(16), c = 10.048(3) ?, β = 109.47°, V = 1634.7(6) ?~3, Z = 4, F(000) = 944, Dc = 1.900 g/cm^3, C(12)H(10)N4O(12)Zn, Mr = 467.61 and μ = 1.584 mm^-1. The whole molecule presents "V" shape. Complex 2 is a centrosymmetric structure in triclinic system with space group P1: a = 7.4728(5), b = 7.6825(6), c = 8.5184(6) ?, α = 65.975(2), β = 79.87(2), γ = 89.855(2)°, V = 4384.1(5) ?~3, Z = 1, F(000) = 256, Dc = 1.908 g/cm^3, C(12)H(14)N4O(14)Zn, Mr = 503.64 and μ = 1.492 mm^-1. Complex 3 is a one-dimensional chain structure belonging to monoclinic system and space group P21/c with a = 4.9456(6), b = 12.5322(14), c = 11.2514(13) ?, β = 97.313(11)°, V = 6916.8(14) ?~3, Z = 2, F(000) = 432, Dc = 2.072 g/cm^3, C(12)H6N4O(10)Zn, Mr = 431.58, and μ = 1.852 mm^-1. In three complexes, six oxygen atoms from the surrounding coordination atoms form a ZnO6 distorted octahedral coordination geometry around the zinc ions. Meanwhile, fluorescent properties of the three complexes were investigated at room temperature. The fluorescence spectroscopic analysis demonstrated that the ligand POA shows red-shift after coordinating with the zinc(Ⅱ) ions.     

创新型综合实验:苯甲酰苯胺的合成*

肟化反应和贝克曼重排反应是高校化学专业重要的基础有机实验,现行的实验教材常采用由环己酮制备己内酰胺,该实验存在反应过程难监测,反应后处理损失大,收率低,实验效果不理想等问题。以二苯甲酮为原料,经肟化、贝克曼重排合成苯甲酰苯胺,产物经1H NMR、13C NMR、IR等确证分子结构。研究结果表明:苯甲酰苯胺合成反应平稳,实验现象明显,后处理简便,收率较高。通过TLC监测反应进程,能使学生对反应过程有清楚的认知和掌控。实验内容和时间适合大学实验要求,实验综合性强,拓展空间大,能够有效训练学生的创新思维和科研意识,提高学生的实验技能。