Intermittent curing and its effect on pulsed laser-induced photopolymerization

Different intermittent curing methods were conducted for pulsed laser induced photopolymerization reactions in a TMPTA acrylic system. Two methods of curing were compared, named grouped pulses impingement (GPI) and consecutively pulsed curing (CPC), respectively, in which the total number of the curing pulses were kept same. In GPI, a prominent light diffraction effect was observed in the post curing process, but was absent in the CPC procedure. A condensed but limited sized core of polymeric structure was the cause of the light diffraction. The amount of inhomogeneity in the refractive index for the core was about 90% of the cured background. Simulations based on Fresnel diffraction theory were performed, and the result was in good agreement with the experimental observations. PACS  42.25.Bs; 61.82.Pv; 82.35.-x     

The ab initio quantum chemical calculation of MgH+ and Mg2H+

The potential energy curve of MgH+ and the potential energy surface of Mg₂H+ are calculated by quantum chemical ab initio SCF MO method with STO-3G basis set. The electronic wave functions and populations are obtained. The eqilibrium internuclear distance of MgH+ is 1.60 Å. There are two possible configurations of Mg₂H+: C and D . The former is (Mg-Mg-H)+, with bond length rM_g-M_g = 2.41Å and rM_g-H =1.63Å. The latter is (Mg-H-Mg)+, with bond length rM_g-H = 1.73Å. The cause of the stability of these species is discussed. The result of calculation about the bond length of MgH+ agrees reasonably well with experimental value. The conclusion about the stability of (Mg-Mg-H)+ ion supports the hypothesis proposed by Porter, based on thermodynamical calculation.     

从石英光纤废料中制备硅新工艺的实验研究

对石英光纤废弃物氢热还原过程进行了热力学分析,并利用X射线衍射分析法(XRD)、激光拉曼光谱(Laser Raman Spectroscopy)、X射线光电子能谱(XPS)及化学分析等对该新工艺进行了实验研究.产物中只检测到硅和氧两种元素且金属键硅质量含量在15%以上,说明该方法不仅可以实现该类危险废弃物的无害化处理,而且还可以作为高纯度太阳级硅的一个潜在的供给渠道,从而弥补太阳能电池硅光伏材料供应的不足.     

A relationship between the Berlekamp-Massey and the euclidean algorithms for linear feedback shift register synthesis

A relationship between the Berlekamp-Massey and the Euclidean algorithms for linear feedback shift register synthesis is established. In fact, by refining a sequence of polynomials appearing in the Euclidean algorithm, the sequence of characteristic polynomials computed by the Berlekamp-Massey algorithm will be achieved. A preliminary version of this paper was presented at the Oberwolfach Information Theory Meeting, May 12–16, 1986.     

Asymptotic behavior of solutions for a class of retarded difference equations

Consider the retarded difference equationx _n −x _n−1 =F(−f(x _n )+g(x _n−k )), wherek is a positive integer,F,f,g:R→R are continuous,F andf are increasing onR, anduF(u)>0 for allu≠0. We show that whenf(y)≥g(y) (resp. f(y)≤g(y)) fory∈R, every solution of (*) tends to either a constant or −∞ (resp. ∞) asn→∞. Furthermore, iff(y)≡g(y) fory∈R, then every solution of (*) tends to a constant asn→∞. Project supported by NNSF (19601016) of China and NSF (97-37-42) of Hunan     

N2O+离子A2Σ+电子态的光解动力学研究

用一束波长为360.55nm的激光，通过N2O分子的（3+1）共振多光子电离（REMPI）过程制备纯净且布居完全处于X2Π(000)态的母体离子N2O+，然后用另一束波长在275—328nm范围内的可调谐激光将制备的N2O+离子激发至预解离电子态A2Σ+.实验发现，由于解离碎片NO+所具有的一定的反冲速度，其TOF质谱峰明显比N2O+母体宽.通过分析NO+碎片TOF质谱峰形状，得到了解离产物的总平均平动能〈ET〉；通过考察〈ET〉随光解能量的变化，发现光解能量在32000cm-1附近约250cm-1的变化 关键词： N2O+离子A2Σ+态 TOF质谱峰 预解离机理     

The orbit method and the Virasoro extension of Diff(S): I. Orbital integrals

Using the finite dimensional example of , the universal covering of PSU(1,1), as a guide, we revisit the orbit method as it applies to , the universal central extension of . We clarify some aspects of the classification of coadjoint orbits, determine boundedness properties of the natural height function on these orbits, and calculate orbital integrals.     

关于电磁学教学的三点建议

本文就电磁学教学中常遇到的问题谈一点教学体会。