关于有界性的勒茹米辛型定理

本文对于泛函微分方程建立了关于有界性的新的勒茹米辛型定理，其中不仅可避免采用不易寻找的函数Ｐ，而且还可以采用若干个含有状态变量ｘ的部分变元的李雅普诺夫函数，这样，本文中所得的结果大大改进了已知结果。一方面，它更易于应用；另一方面，保证有界性的条件较少限制，并且，还给出了一些例子来说明所得结果的优越性。     

数学问题解答

2005年10月号问题解答(解答由问题提供人给出)1576求函数y=cscx-cotxarctan94≤x≤arctan23的值域.解如图,构造一组邻边分别为3、4,4、6的矩形ABCF,CDEF,P为线段BC上的任意一点,则∠EBD=arctan94,∠ECD=arctan32,∠EPD=x,BE=97,CE=213,PE=4cscx,PD=4cotx,PB=9-4cotx,PC=4cotx-6,由PE+PB≥BE,即4cscx+9-4cotx≥97,有cscx-cotx≥974-9①又PE-PC≤CE,即4cscx-4cotx+6≤213,有cscx-cotx≤132-3②由①、②,得974-9≤cscx-cotx≤13-32,即所求值域为974-9,132-3.1577D是△ABC的边AB的中点,E是BC边上的点,且AC=EB-EC,在边C…     

Double Jet Emission of Hot Electrons from a Micro-droplet Spray

Spatial distribution of hot electrons with energies above 50 keV are investigated by an ethanol micro-droplet spray irradiated by linearly and elliptically polarized 150 fs laser pulses at an intensity of 10^18 W/cm^2. Two symmetric hot electron jets with respect to the laser propagation direction are observed in the polarization plane for a     

Quantum spectra and classical periodic orbit in the cubic billiard

Quantum billiards have attracted much interest in many fields. People have made a lot of researches on the two-dimensional (2D) billiard systems. Contrary to the 2D billiard, due to the complication of its classical periodic orbits, no one has studied the correspondence between the quantum spectra and the classical orbits of the three-dimensional (3D) billiards. Taking the cubic billiard as an example, using the periodic orbit theory, we find the periodic orbit of the cubic billiard and study the correspondence between the quantum spectra and the length of the classical orbits in 3D system. The Fourier transformed spectrum of this system has allowed direct comparison between peaks in such plot and the length of the periodic orbits, which verifies the correctness of the periodic orbit theory. This is another example showing that semiclassical method provides a bridge between quantum and classical mechanics.     

Hydrothermal and Solvothermal Synthesis of the Complex Fluoride α′-SrAlF_5

Introduction　　Strontiumaluminumpentafluoride SrAlF5isagoodhostforthespectralresearchofdopedrareearthionsduetoitsweakcrystalfieldenvironment.Forthefirsttime ,Hewesetal.1foundthef→flineemissionoftheEu2 + inSrAlF5matrix ,andfournonequivalentsitesforRE2 + inSrAlF5havealsobeenreported .2 Theobservationofthetunable laserofCr3+ from 85 2to 94 7nminSrAlF5hasat tractedconsiderableattention3andtheferroelectricbehav ior4 ofSrAlF5hasextendeditsapplicablefield .Twogener almethods,high temperatur…     

Influence of Growth Temperature and Trimethylindium Flow of InGaN Wells on Optical Properties of InGaN Multiple Quantum-Well Violet Light-Emitting Diodes

An InGaN multiple-quantum-well (MQW) violet-light-emitting diode (LED) is grown by low-pressure metalorganic chemical vapour deposition. It is found that photoluminescence wavelength of the InGaN MQW violet LED is lengthened with increasing growth temperature and with the increasing trimethylindium flow of the InGaN wells. The electroluminescence peak wavelength of the violet LED are about 401 nm with full width at half maximum of 14nm, and the output power in injection current of 2OmA at room temperature is 4.1mW.     

评冯端、金国钧著《凝聚态物理学》（上卷）（高等教育出版社出版）

凝聚态物理是涉及面很广而又充满活力的学科．它描述自然界物质存在的最普遍形态，又是高新技术的基础．两次诺贝尔物理奖得主Bardeen曾不止一次将凝聚态物理比作一棵根深叶茂的大树，有些枝干会成熟、干枯，但会不断冒出新芽，长成新枝，开花结果．这是一幅很生动的写照．