基于太赫兹光谱检测的危险品模糊识别研究

在采用太赫兹时域光谱(THz-TDS)技术对7种常见危险品进行实验研究并得到它们在0.2～2.6 THz频率范围的特征吸收谱的基础上,用模糊识别方法对7种常见危险品的太赫兹特征吸收谱进行了训练和识别。将爆炸物RDX(黑索金)、γ-HNIW、DNT(2,4-二硝基甲苯)及毒品MA(甲基苯丙胺)、氯胺酮等的不同特征吸收峰作为模糊聚类分析数据源,利用相关系数法建立模糊相似矩阵,借助传递闭包法获得模糊等价矩阵,形成标准太赫兹吸收光谱模型库,采用极差分析进行数据预处理,计算海明贴近度,识别待检物品为隐蔽在军服后的RDX和毒品MDA(替苯丙胺)。研究结果表明,由分子间相互作用或声子共振模式引起的不同特征吸收是确定危险品类型和种类的依据,用模糊识别可以实现对不同种类危险物品的识别和鉴定,为太赫兹光谱技术用于危险品的检测和识别提供了一种新的有效方法。     

Analytical solutions to the electromagnetic field in a cylindrical shell excited by external axial current

The solutions to the electromagnetic field excited by a long axial current outside a conductive and magnetic cylindrical shell of finite length are studied in this paper. The more accurate analytical solutions are obtained by solving the proper boundary value problems by the separation variable method. Then the solutions are simplified according to asymptotic formulas of Bessel functions. Compared with the accurate solutions, the simplified solutions do not contain the Bessel functions and the inverse operation of the singular matrix, and can be calculated out fast by computers. The simplified solutions are more suitable for the cylindrical shell of high permeability and conductivity excited by a high frequency source. Both of the numerical results and the physical experimental results validate the simplified solutions obtained.     

Analytical solutions of transient pulsed eddy current problem due to elliptical electromagnetic concentrative coils

The electromagnetic concentrative coils are indispensable in the functional magnetic stimulation and have potential applications in nondestructive testing.In this paper,we propose a figure-8-shaped coil being composed of two arbitrary oblique elliptical coils,which can change the electromagnetic concentrative region and the magnitude of eddy current density by changing the elliptical shape and/or spread angle between two elliptical coils.Pulsed current is usually the excitation source in the functional magnetic stimulation,so in this paper we derive the analytical solutions of transient pulsed eddy current field in the time domain due to the elliptical concentrative coil placed in an arbitrary position over a half-infinite plane conductor by making use of the scale-transformation,the Laplace transform and the Fourier transform are used in our derivation.Calculation results of field distributions produced by the figure-8-shaped elliptical coil show some behaviours as follows:1) the eddy currents are focused on the conductor under the geometric symmetric centre of figure-8-shaped coil;2) the greater the scale factor of ellipse is,the higher the eddy current density is and the wider the concentrative area of eddy current along y axis is;3) the maximum magnitude of eddy current density increases with the increase of spread angle.When spread angle is 180,there are two additional reverse concentrative areas on both sides of x axis.     

一价Na元素对LaMnO3母体A位掺杂的磁电性质的影响

通过测量La1-xNaxMnO3(x=0.05、0.10、0.15、0.20、0.25、0.33)体系的M～T曲线和R～T曲线,研究了La位Na掺杂对体系磁电性质的影响.结果发现:随着Na掺杂浓度的增加,体系居里温度Tc升高,顺磁-铁磁相变逐渐变陡;伴随着顺磁-铁磁相变,体系发生金属-绝缘体相变,电阻随掺杂浓度增加而下降.体系磁电性质的变化来源于掺杂引起的Mn3 -O-Mn4 间的双交换作用、静态Jahn-Teller畸变和公差因子的变化.     

Co:BaTiO3/Si(100)纳米复合薄膜制备、微结构及其紫外光电子能谱研究

采用脉冲激光气相沉积(PLD)方法,在Si(100)晶面上制备了Co:BaTiO₃纳米复合薄膜.采用X射线衍射(XRD)结合透射电镜(TEM)方法研究了两种厚度Co:BaTiO₃纳米复合薄膜的晶体结构,当薄膜厚度约为30 nm时,薄膜为单一择优取向;当薄膜厚度约为100nm时,薄膜呈多晶结构.原子力显微镜(AFM)分析表明,当膜厚为30nm时,薄膜呈现明显的方形晶粒.采用紫外光电子能谱(UPS)研究了Co的价态和Co:BaTiO₃纳米复合薄 关键词： 3')" href="#">BaTiO₃ 纳米复合薄膜 紫外光电子能谱     

Sm填充skutterudite化合物中填充原子扰动效应研究

结合Rietveld结构解析和拉曼光谱对单相多晶的Sm原子填充的skutterudite化合物Sm_yFe_xCo_4-xSb₁₂进行了分析.Rietveld精确化结果表明：Sm_yFe_xCo_4-xSb₁₂化合物具有填充式skutterudite结构,Sm原 关键词： 方钴矿 Rietveld结构解析 拉曼散射 扰动     

沉降介质对单分散SiO2微球重力组装欧泊模板的影响

 以氨水作催化剂、正硅酸乙酯为硅源、乙醇为溶剂,采用改进溶胶-凝胶法制备了系列单分散SiO₂微球,研究了平均粒径为250,280,320 nm单分散SiO₂微球在水、无水乙醇、丙酮等介质中的沉降与自组装过程。还对单分散体系重力沉降组装欧泊模板的形成机理进行了讨论。SEM表明,微球在无水乙醇和丙酮沉降介质中均能组装形成3维有序密堆积结构的欧泊,但在无水乙醇中要优于在丙酮中。沉降速度实验表明,相同粒径的单分散SiO₂微球在水、乙醇、丙酮作为沉降介质中的沉降速度相差并不大,沉降介质对重力水平沉降组装模板的影响主要是由于其表面张力与粘度不同造成的。     

PS-RF双层空心微球的制备

 采用聚苯乙烯(PS)空心微球为模板,间苯二酚-甲醛(RF)为前驱体溶液,邻苯二甲酸二丁酯为分散剂,以界面聚合反应为基础初步总结出一条PS-RF双层聚合物空心微球的制备工艺,并就制备过程中RF溶液与分散剂油相的选择、预聚时间、搅拌速率、固化温度等影响因素进行了讨论。当RF溶液质量分数为25%,间苯二酚与碳酸钠的物质的量之比为100,预聚24 h,搅拌速率120～200 r/min,固化温度35 ℃时,制得了球形度和同心度达到95%以上,表面粗糙度小于10 nm的PS-RF双层空心微球。     

电子回旋共振微波等离子体刻蚀α:CH薄膜的工艺

 为了刻蚀出图形完整、侧壁陡直、失真度小的α:CH薄膜微器件,研究了有铝和无铝掩膜、气体流量比、工作气压对刻蚀速率的影响,并对纯氧等离子体刻蚀稳定性进行了研究。研究结果表明：在相同条件下,刻蚀速率随刻蚀时间变化不大;a:CH薄膜上有铝和无铝掩膜时,刻蚀速率相同;流量一定时,刻蚀速率随氩气和氧气体积比的增大而降低,当用纯氩气时,几乎没刻蚀作用;刻蚀速率随工作气压的增大而降低。实验中,得到最佳刻蚀条件是：纯氧气,流量4 mL·s^-1,工作气压9.9×10^-2 Pa,微波源电流80 mA,偏压-90 V。     

间苯二酚-甲醛气凝胶空心微球制备技术

 采用微流体注射成型技术,以邻苯二甲酸二丁酯为内外油相,间苯二酚/甲醛(RF)溶液为水相,经过溶胶-凝胶、溶剂交换、超临界干燥等过程制备出了RF气凝胶空心微球。分别采用红外光谱、光学显微镜、X光显微分析、透射电镜(TEM)、N­₂吸附-脱附,对RF空心微球成分、形貌、孔径、直径分布等进行表征。结果表明：RF为单层空心微球,具有典型的气凝胶多孔结构,由粒径为10 nm左右、且粒度分布较为均匀的纳米粒子构成,平均孔径为20 nm左右,球形度和同心度大于95%,微球直径分布在550～750 mm,最大可达到800 mm,达到了快点火靶的基本要求。