强激光大气传输中拉曼散射的数值计算

用经典理论推导了强激光大气传输中由于氮的转动受激Ｒａｎｍａｎ散射所造成的对传输功率的限制方程，并计算了光强的阈值，得到了阈光强与激光波长和脉宽的关系；此外，还研究了二维效应和激光脉冲系列通过大气时声子激发的累加效应。     

生长素自旋标记物的合成及生物活性

将４－氧－２，２，６，６－四甲基哌啶－１－氧自由基（ＴＭＰＯ）与３种植物生长素拼接在一起，合成了相应的腙，以研究ＴＭＰＯ对生长素活性的影响．所得化合物的结构通过ＩＲ、ＥＳＲ、元素分析或ＭＳ加以证实．初步生物活性测定表明，与母体相比不仅对绿豆幼苗的生长促进作用无影响，在一定条件下还增强了促进生长的活性     

A High Gain and Broadband C-Band Aperture-Coupled Patch Antenna

A aperture-coupled patch antenna is designed with parasitic elements connecting to the rectangle ring on the bottom of antenna substrate through metal vias, which lead the current induced by patch radiator to the top surface of antenna substrate. Therefore, the effective radiation is enhanced and higher gain is achieved. The bandwidth is broadened simultaneously due to the structure of aperture-coupled patch antenna with parasitic elements. Compared to the conventional aperture-coupled patch antenna, the antenna gain increases averagely 2 dB due to the novel structure. Compared to patch antenna of electromagnetic band-gap, the dimensions of novel patch antenna greatly decreases, which can be used as element in the array antenna. Two kinds manufactured antenna are both measured in an anechoic chamber. The good agreements between numerical simulation and experimental prototype have been obtained.     

Study on the complex-formation reaction of yttrium with para-methyl-chlorophosphonazo(CPApM)

Yttrium forms with CPApM a 1:2 α-complex instantaneously in acidic medium. At pH～5 (buffer solution), the α-complex is transformed to a β-complex with an absorption peak at 755 nm after standing. The transformation reaction is a first-order reaction. The rate constant and the apparent activation energy were found to be 9.67 × 10^?1 min^?1 and 52.3 kJ·mol^?1 respectively. The mechanism of the reaction shows that the β-complex (Y:CPApM=2:4) is formed by combining two molecules of α-complex with the liberation of one proton.     

Optimal training sample allocation and asymptotic expansions for error rates in discriminant analysis

The sample-based rule obtained from Bayes classification rule by replacing the unknown parameters by ML estimates from a stratified training sample is used for the classification of a random observationX into one ofL populations. The asymptotic expansions in terms of the inverses of the training sample sizes for cross-validation, apparent and plug-in error rates are found. These are used to compare estimation methods of the error rate for a wide range of regular distributions as probability models for considered populations. The optimal training sample allocation minimizing the asymptotic expected error regret is found in the cases of widely applicable, positively skewed distributions (Rayleigh and Maxwell distributions). These probability models for populations are often met in ecology and biology. The results indicate that equal training sample sizes for each populations sometimes are not optimal, even when prior probabilities of populations are equal.     

Study of photoreaction in dichromated gelatin by laser photoacoustic technique

 An experimental method to study the photochemical reaction in solid-state dichromated gelatin during exposure is proposed, in which two laser sources with different wavelengths are used to induce photoreaction and to excite photoacoustic signal, respectively. This method is to obtain the real-time characteristics during the formation of the photoreaction product. The curve is fitted using the Rosencwaig-Gersho (R-G) theory and chemical kinetics. The reaction order and the rate of reaction may be obtained by fitting the parameters. The results show that photochemical reaction in dichromated gelatin conforms to the mechanism suggested by Watanable-Westheimer, and the photosensitivity of the samples, prepared under different conditions, is dependent on the initial concentration of photoactive ions. Received: 18 April 1995/Revised version: 3 May 1996     

Production of fumaric acid by immobilized rhizopus using rotary biofilm contactor

Rotary biofilm contactor (RBC) is a reactor consisting of plastic discs that act as supports for micro-organisms. The discs are mounted on a horizontal shaft and placed in a medium-containing vessel. During nitrogen-rich growth phase, mycelia ofRhizopus oryzae ATCC 20344 grew on and around the discs and formed the “biofilm” of self-immobilized cells on the surface of the plastic discs. During the fermentation phase, the discs are slowly rotated, and the biofilms are exposed to the medium and the air space, alternately. With RBC, in the presence of CaCO₃,Rhizopus biofilm consumes glucose and produces fumaric acid with a volumetric productivity of 3.78 g/L/h within 24 h. The volumetric productivity is about threefolds higher with RBC than with a stirred-tank fermenter with CaCO₃. Furthermore, the duration of fermentation is one-third of the stirred-tank system. The immobilized biofilm is active for over a 2-wk period with repetitive use without loss of activity.

     

Effects of a Degeneracy in the Competition Model: Part II. Perturbation and Dynamical Behaviour

This is the second part of our study on the competition model where the coefficient functions are strictly positive over the underlying spatial region Ω except b(x), which vanishes in a nontrivial subdomain of Ω, and is positive in the rest of Ω. In part I, we mainly discussed the existence of two kinds of steady-state solutions of this system, namely, the classical steady-states and the generalized steady-states. Here we use these solutions to determine the dynamics of the model. We do this with the help of the perturbed model where b(x) is replaced by b(x)+ε, which itself is a classical competition model. This approach also reveals the interesting relationship between the steady-state solutions (both classical and generalized) of the above system and that of the perturbed system.     

Coloring of Double Disk Graphs

We study the problem of minimizing the number of colors for vertex-coloring of double disk graphs and in this note, show a polynomial-time 31-approximation for the problem, which improves an existing result.     

Kp,q-factorization of complete bipartite graphs

Let K _m,nbe a complete bipartite graph with two partite sets having m and n vertices, respectively. A K _p,q-factorization of K _m,n is a set of edge-disjoint K _p,q-factors of K _m,n which partition the set of edges of K _m,n. When p = 1 and q is a prime number, Wang, in his paper “On K _1,k -factorizations of a complete bipartite graph” (Discrete Math, 1994, 126: 359—364), investigated the K _1,q -factorization of K _m,nand gave a sufficient condition for such a factorization to exist. In the paper “K _1,k -factorizations of complete bipartite graphs” (Discrete Math, 2002, 259: 301—306), Du and Wang extended Wang’s result to the case that q is any positive integer. In this paper, we give a sufficient condition for K _m,n to have a K _p,q-factorization. As a special case, it is shown that the Martin’s BAC conjecture is true when p : q = k : (k+ 1) for any positive integer k.