瞬态热响应的条元半解析法

由卷积型变分原理出发，针对二维瞬态热响应问题，在空间域采用三角函数加补充项的有限条法，在时间域取解析函数，得到求解瞬态热响应的条元半解析法计算列式．     

Weak convergence of weighted empirical type processes under contiguous and changepoint alternatives

Let X₁, X₂,… be independent random variables. We study asymptotic behaviour of two-time parameter empirical type processes based on observations, ranks and sequential ranks. We introduce weight functions and derive the limiting distributions of these processes under the null hypothesis of X_i being identically distributed, as well as under a class of continguous alternatives which can accommodate the possible occurrence of a changepoint in the series of measurements.     

非线性四阶椭圆型方程的极大值原理

文中考察了一类非线性四阶椭圆型方程,构造了其解的某种泛函,导出了该泛函满足极大值原理的条件。由此可得到该方程解、解的梯度及椭圆算子等的估计。     

The local time of iterated Brownian motion

We define and study the local time process {L ^*(x,t);x¹,t0} of the iterated Brownian motion (IBM) {H(t):=W ₁(|W ₂ (t)|); t0}, whereW ₁(·) andW ₂(·) are independent Wiener processes.Research supported by Hungarian National Foundation for Scientific Research, Grant No. T 016384.Research supported by an NSERC Canada Grant at Carleton University, Ottawa.Research supported by a PSC CUNY Grant, No. 6-66364.     

Knowledge-based systems for analytical chemistry

Analytical chemists have made extensive use of computer technology, automating most analytical instruments, many analyses and reporting activities. We now need to expand the areas to which computers can be applied by addressing problems of greatly increased complexity. These problems fall into two general classes, the first class of problems are those thatcannot be solved using only first principle information and, the second class are those problems thatcan be solved using only first principles, but that are so complex that the traditional approach is often not cost effective.The discussion will center on how artificial intelligence technology (AI) can provide the means for using heuristics together with first principle information to solve instances of the first class of problems. The knowledge required to provide the solution is formulated as facts, rules (heuristics) and an inference engine.The same AI technology can also be used to refine specifications and provide cost effective solutions for very complex problems involving only first principle information. For this class of problems an AI work station can provide the software development conductive to rapid prototyping and specification refinement.Discussion of several expert systems will be used to describe the capabilities and features of rule-based systems. The strengths and weaknesses of one system, use of IR spectra for structure elucidation, will be examined in some detail. It is an expert system consisting of rule sets organized into logic trees, thus it will provide an opportunity to describe how the use of more advanced AI technology could further improve the program's performance.     

Significant reduction of on-site Coulomb energy U due to short-range correlation in an organic Mott insulator.

By carrying out a first-principles T-matrix calculation on multiple scatterings between electrons, we show that the intramolecular electron-electron interaction energy U, of a Mott insulator of the organic radical 1,3,5-trithia-2,4,6-triazapentalenyl (TTTA) is significantly reduced from the naive expectation value of the Coulomb interaction (7.3 eV and 5.3 eV, respectively, for the bare and screened Coulomb interactions) to 2.9 eV due to the short-range correlation. This result together with the intermolecular interaction energy D=1.3 eV explains the experimental optical gap (1.5 eV). The associated two-particle wavefunction clearly shows the Coulomb hole indicating that two electrons with antiparallel spins cannot approach because of the Coulomb repulsion. We also discuss the energetics and magnetics of this system.     

Freezing temperatures and enthalpies of dilution of aqueous solutions of amides. Gibbs energies and enthalpies of interaction of the N,N-dimethylamide group in aqueous solutions

Enthalpies of dilution, freezing temperatures, and densities of aqueous solutions of N,N-dimethylacetamide and N,N-dimethylpropionamide have been measured. Freezing temperatures of dilute aqueous solutions of formamide and N,N-dimethylformamide have also been measured. These data yield the pairwise molecular Gibbs energies and enthalpies of interaction: these have been treated according to a group additivity principle to give pairwise functional group Gibbs energies and enthalpies of interaction. The results indicate that substitution on the amide nitrogen may increase the Gibbs energy and enthalpy of interaction of the amide group with itself in an aqueous environment but the effect if present is small.     

Rank order statistics for time series models

Some invariance principles are obtained for the one-sample rank order statistics of a -mixing or strong mixing type time series. The estimation of the center of symmetry of the time series and tests for serial dependence are considered as applications.     

A stochastic variational approach to viscous Burgers equations

We consider viscous Burgers equations in one dimension of space and derive their solutions from stochastic variational principles on the corresponding group of homeomorphisms. The metrics considered on this group are L ^p metrics. The velocity corresponds to the drift of some stochastic Lagrangian processes. Existence of minima is proved in some cases by direct methods. We also give a representation of the solutions of viscous Burgers equations in terms of stochastic forward-backward systems.     

非晶SiO2薄膜中氧双键缺陷电子及光学特性的第一性原理研究

利用第一性原理对离子溅射沉积的非晶SiO2薄膜微观结构进行了分析、研究,结果表明,氧双键缺陷（SGs）可以作为体缺陷稳定存在于非晶SiO2中,SGs缺陷导致非晶SiO2薄膜材料禁带中引入了新的电子态,减小了禁带宽度;同时采用时相关密度泛函理论（TDDFT）对其光学特性进行了研究,得到非晶SiO2薄膜介电常数与入射光子能量间的关系曲线,从介电常数的虚部发现SGs缺陷在3.6eV处存在一个光学吸收峰。