地方时与区时在电离层研究中的差异

本文指出混淆地时与区时两个时间概念在电离层研究中带来的差异的严重性，建议使用地方与区时这两个名词，而抛弃“本地时”和“当地时”等容易引起混淆的名词。     

An approach to automated detection of tumors in mammograms

An automated system for detecting and classifying particular types of tumors in digitized mammograms is described. The analysis of mammograms is performed in two stages. First, the system identifies pixel groupings that may correspond to tumors. Next, detected pixel groupings are subjected to classification. The essence of the first processing stage is multiresolution image processing based on fuzzy pyramid linking. The second stage uses a classification hierarchy to identify benign and malignant tumors. Each level of the hierarchy uses deterministic or Bayes classifiers and a particular measurement. The measurements pertain to shape and intensity characteristics of particular types of tumors. The classification hierarchy is organized in such a way that the simplest measurements are used at the top, with the system stepping through the hierarchy only when it cannot classify the detected pixel groupings with certainty.     

Variational study of vacuum structure with fermions ind+1 dimensional Hamiltonian lattice gauge theory

The physical vacuum state and general expression for the Hamiltonian ofd+1 dimensional lattice gauge theory are given by incorporating the exact ground state of pure gauge theory and the variational fermion vacuum state. The applications toSU(2) andSU(3) gauge theories in 2+1 and 3+1 dimensions are demonstrated and the fermion condensates \(\left\langle {\bar \psi \psi } \right\rangle \) as functions of 1/g ² are calculated.     

Convergence of the fractional step Lax-Friedrichs scheme and Godunov scheme for the isentropic system of gas dynamics

A convergence theorem of the fractional step Lax-Friedrichs scheme and Godunov scheme for an inhomogeneous system of isentropic gas dynamics (1<5/3) is established by using the framework of compensated compactness. Meanwhile, a corresponding existence theorem of global solutions with large data containing the vacuum is obtained.Partially supported by U.S. NSF Grant # DMS-850403     

Na2SnO3系催化剂在甲烷氧化偶联反应中的催化性能及表面碱性的探讨

1982年Keller和Bhasin以金属氧化物为催化剂从甲烷制得少量乙烯和乙烷的工作引起了各国研究工作者的重视,此后报道了许多有研究价值的催化剂,其中添加碱金属对提高催化性能所起的作用引起了普遍的关注.Lunsford等首先用添加Li~+的MgO作催化剂,发现催化剂表面碱性增强的同时,生成C_2烃类产物的选择性明显增加.随后Iwamatu等在MgO中添加Na~+及Rb~+盐,Jones等在Mn~(4+)/SiO_2中添加Na~+,Otsuka等在Sm_2O_3中添加LiCl作为甲烷氧化偶联催化剂进行了研究,这些结果均表明,因添加碱金属使催化剂呈现     

电沉积富铁Fe-Ni合金箔工艺的研究

对硫酸盐-氯化物电解液中电沉积富铁Fe-Ni合金箔的工艺进行了研究,讨论了电解液组成、电流密度、温度及pH值等因素与合金箔组成之间的相互关系,得到了制备富铁合金箔的最佳镀液组成及工艺条件,并通过实验确定在阴阳极比为1:2时,镍铁联合阳极配比为1.5:1.通过扫描电镜,能谱和X-衍射对富铁Fe-Ni合金箔的形貌及结构进行分析表明合金箔晶粒细致,尺寸均匀,结构紧密,表面光滑平整,无孔洞和裂纹,晶粒结构为(111),(200),(311)及(222)织构,并表现为较强的(111)择优取向.     

硫酸根阴离子对HPMBP及TOA协同萃取镨(Ⅲ)及钕(Ⅲ)的影晌

本文研究了硫酸根阴离子对1-苯基-3-甲基-4-苯甲酰基吡唑酮-5(HPMBP,HL)及三辛胺(TOA)协同萃取镨(Ⅲ)及钕(Ⅲ)的影响。发现在SO_4~(2-)体系中协萃机理为:(LnL_3)_o+(HTOAL)_o(HTOA~+LuL_4~-)_o及(HLnL_4)_o+(TOA)_o(HTOA~+LnL_4~-)_o式中Ln~(3+)=Pr~(3+),下标“o”指示有机相中物种,无下标指示水相中物种。固体萃合物的红外光谱及元素分析数据确证了上述机理。