Fiber-optic reflex sensor for in-line production measurement

The paper describes experiments concerning distance measurement with fiber-optic sensor and improvement of the measurement principle. The sensor probe was well-designed with a small structure and multi-function. The novel optical fiber probe arrangement as well as the possibilities of use for complex measurement problems are explained using the measurement of an internal screw thread as an example. The experimental results show that the measurement uncertainty of the thread minor diameter can reach ±10 μm, and the stability of the measurement system is better than 0.07%.     

自制金割效应物理摆的研究性实验

金割效应物理摆是将数学中的优选法与物理实验中的复摆结合起来并用计算机处理数据的自制教学仪器.把金割效应物理摆作为研究性实验进行开设,更有利于培养学生的开拓精神和创新能力.     

Kolmogorov Width of Classes of Smooth Functions on the Sphere

Let ^d−1{(x₁,…,x_d) ^d:x²₁+···+x²_d=1} be the unit sphere of the d-dimensional Euclidean space ^d. For r>0, we denote by B^r_p (1p∞) the class of functions f on ^d−1 representable in the formwhere dσ(y) denotes the usual Lebesgue measure on ^d−1, and P^λ_k(t) is the ultraspherical polynomial.For 1p,q∞, the Kolmogorov N-width of B^r_p in L^q( ^d−1) is given bythe left-most infimum being taken over all N-dimensional subspaces X_N of L^q( ^d−1).The main result in this paper is that for r2(d−1)²,where A_NB_N means that there exists a positive constant C, independent of N, such that C⁻¹A_NB_NCA_N.This extends the well-known Kashin theorem on the asymptotic order of the Kolmogorov widths of the Sobolev class of the periodic functions.     

Electron–hole complexes in self-assembled quantum dots in strong magnetic fields

We present results of calculations and experiments on electron–hole complexes in InGaAs/GaAs self-assembled quantum dots in high magnetic field (B). Due to hidden symmetries, the chemical potential of an N-exciton system at special B fields becomes insensitive to the exciton number as well as the magnetic field. This results in plateau regions of high intensity in measured magneto-PL spectrum. Theoretical calculations using exact diagonalization techniques successfully explain the measured magneto-photoluminescence spectrum with B fields up to 28 T.     

一种不等带宽光学梳状滤波器

提出了一种新型—Michelson—三面镜FabryPerot型50GHz不等带宽光学梳状滤波器设计方案,分析和模拟表明:该器件将一路信道间隔为50GHz的输入信号分离成信道间隔为100GHz的奇偶两路输出信号,其中在3dB处,奇数信道带宽大于30GHz用于10Gb/s传输,偶数信道带宽大于60GHz用于40Gb/s传输对于将来的40Gb/s系统,该器件具有优势.     

U：CaF2晶体的分凝特性与光谱性质

应用TGT法生长了直径为75mm的U：CaF2晶体，宏观上透明完整.应用公式K0=Cs/Cl计算了U在CaF2晶体中的分凝系数等于0.53.应用溶质分布一般公式Cs=K0C0(1-g)K0-1，计算U的浓度分布与测量值，数值符合说明晶体生长过程接近平衡状态.分析不同条件下生长的U: CaF2晶体的晶胞参数和吸收光谱，结果表明生长气氛决定U的价态及电荷补偿机理：无PbF2存在的条件下，U为+4价，晶体呈绿色；PbF2的加入起到氟化去氧作用，U倾向于以离子半径最接近于Ca2+的U3+存在，晶体呈红色.从晶体生长开始到结束的部位，U3+:CaF2晶体吸收光谱的峰位不变，峰强呈现与U浓度相同的增加趋势.U3+:CaF2晶体外层厚约5mm处呈黄色，含有U3+和U2+的混合价态离子，其原理是石墨坩埚的还原作用通过单质铅，使部分的U3+进一步还原成了U2+. 关键词： 铀 氟化钙晶体 分凝系数 晶胞参数     

Efficient microwave induced direct α-halogenation of carbonyl compounds

A novel and direct method for the synthesis of α-halocarbonyl compounds using sequential treatment of carbonyl compounds with [hydroxy(tosyloxy)iodo]benzene followed by magnesium halides under solvent-free microwave irradiation conditions is described.     

多媒体在二维动量实验中的应用

利用VisualBasic的多媒体功能和CCD摄像头以及气垫桌等组成的实验系统，演示了二维碰撞中的动量守恒．