自制教具在实际运用中的效果反思

结合自制的一些教具,展示了自制教具在教学中所取得的效果     

实验教学综合管理系统的研究与实践

实验教学在理工科学生实践教学中占有重要地位,但随着招生规模的扩大,对实验教学管理的信息化提出了更高要求,本系统利用ASP与SQL Server数据库技术,将实验预约、成绩管理、教师工作量统计、数据库管理等模块集成到系统中,实现了教学管理中各种资源的优化配置,大大提高了教学管理效率。     

新型测地声呐——GPY高分辨地层剖面仪

本文介绍了一种能工作于特浅水域的高分辨地层剖面仪。首先分析了国际现有产品存在的技术问题,然后阐述GPY中所采用的声学和信号处理上的新技术,最后介绍它的主要技术特点及应用效果。     

大学物理演示教学模式初探

本介绍了我校大学物理演示的教学模式,教学管理的具体做法,为吸引学生积极参与演示实验的措施及发展思路等。     

大学物理实验教学改革探析

实验改革是提高实验教学效果的有效途径,为提高大学物理实验的教学效果,本文针对大学物理实验教学实际,从实验教学内容、教学方法和手段、教学管理等进行了深入探讨,提出了进一步优化教材、改进教学方法、建立信息化网络等措施.实现了学员利用信息平台自主预约、自主学习,获取相关实验内容及与军事相关的前沿知识,使学员在创新能力、分析问题、解决问题的能力等方面得到了不同程度的提高.     

《 大学物理实验教学管理系统》的开发设计

从北京科技大学天津学院物理实验教学和管理的实际需求出发, 对大学物理实验教学管理系统进行了 设计与研究; 主要从大学物理实验教学管理系统的设计需求、 总体结构设计、 功能设计、 页面设计等几个方面对系统 的研究成果进行了总结; 目的是通过该系统平台的构建, 实现教学资源共享、 教学管理信息化、 规范化、 系统化, 解决 实验教学过程中出现的预习难、 复习难、 管理难的问题, 从而改善实验教学效果和提高管理效率     

投影栅相位法三维形体检测精确解相方法的研究

根据投影栅相位法三维检测实际应用中所遇到的频域处理的移频问题和被测物体与参考面的对应关系问题,分析了它们对解相精度的影响,提出了不移频和全场参考面的解决方法,经实例验证,它们在工程各取得了满意的效果     

平抛运动实验的改进

针对高中平抛运动实验中所用器材分散、描点效果不理想的缺点,对实验装置进行了改进. 改进的装置由J2135型碰撞实验器、绘图板和底板组成,并增加了活动托板和"L"型定位器等装置. 改进后的装置操作简便,运动轨迹描绘准确.     

物理课堂教学管理模式的非主流

经历了3年的新课程改革,更新了教材,同时也学到了许多创新的教学方法,本文从教学管理方法上,结合实际教学,总结出一些创新的管理模式,供同行参考．     

开放式实验教学管理系统的设计与应用

开发了一套基于B/S模式的开放式实验管理系统,介绍了系统设计及主要功能模块。教学管理实践表明,本系统的使用可以提高实验室的资源使用率、实验教学质量及管理水平。     

A Convergence exponent for multidimensional continued-fraction algorithms

We study a convergence exponent of multidimensional continued-fraction algorithms (MCFAs). We provide a dynamical systems interpretation for this exponent, then express a general relation for the exponent in terms of the Kolmogorov-Sinai (KS) entropy and smallest eigenvalue of the associated shift map. We consider the case of approximating two irrationals and demonstrate the numerical method for using the smallest eigenvalue and entropy to evaluate for several MCFAs, including Jacobi-Perron and GMA (generalized mediant algorithm). On very general grounds, the bounds for this exponent (for two irrationals) are 13/2=1.5. The upper bound is attained for algorithms with best approximation properties. We find _GMA=1.387 and _JP=1.374, as well as the values for the KS entropy and Oseledec eigenvalues.     

On the upper critical dimension of lattice trees and lattice animals

We give a rigorous proof of mean-field critical behavior for the susceptibility (=1/2) and the correlation length (v=1/4) for models of lattice trees and lattice animals in two cases: (i) for the usual model with trees or animals constructed from nearest-neighbor bonds, in sufficiently high dimensions, and (ii) for a class of spread-out or long-range models in which trees and animals are constructed from bonds of various lengths, above eight dimensions. This provides further evidence that for these models the upper critical dimension is equal to eight. The proof involves obtaining an infrared bound and showing that a certain square diagram is finite at the critical point, and uses an expansion related to the lace expansion for the self-avoiding walk.     

On Shor’s Channel Extension and Constrained Channels

Several equivalent formulations of the additivity conjecture for constrained channels, which formally is substantially stronger than the unconstrained additivity, are given. To this end a characteristic property of the optimal ensemble for such a channel is derived, generalizing the maximal distance property. It is shown that the additivity conjecture for constrained channels holds true for certain nontrivial classes of channels. After giving an algebraic formulation for Shors channel extension, its main asymptotic property is proved. It is then used to show that additivity for two constrained channels can be reduced to the same problem for unconstrained channels, and hence, global additivity for channels with arbitrary constraints is equivalent to additivity without constraints.     

High-temperature series for scalar-field Lattice models: Generation and analysis

An implementation of the free-embedding scheme for high-temperature series generation on the body-centered cubic family of lattices in arbitrary dimensiond is, described. Series to order 21 in inverse temperature are tabulated for several scalar field models, both for the magnetic susceptibility and for the second moment of the spin correlation function. The critical behavior of a family of 3-dimensional double Gaussian models, which interpolate continuously between the spin-1/2 Ising model and the Gaussian model, is analyzed in detail away from the Gaussian model limit using confluent inhomogeneous secondorder differential approximants. With our best estimate of the correction-to-scaling exponent,=0.52±0.03, the leading exponents for the susceptibility and correlation length for this family are consistent with universality and are given by=1.237±0.002 and =0.630±0.0015, respectively, and=2–/=0.0359±0.0007.     

Excitation functions and isomeric ratios in the reaction130Te (α,xpyn) for α-particle energies between 15 and 37 MeV

The¹³⁰Te(,n)¹³³Xe,¹³⁰Te(,p)¹³³I,¹³⁰Te(,pn)¹³²I and¹³⁰Te(, n)¹²⁹Te excitation functions for alpha particle energies between 14.7 and 36.5 MeV are presented. Excitation functions for the last three reactions are measured for the first time and more consistent results for (, n) are obtained. The isomeric ratios for the ( n), (, pn) and (, n) reactions were deduced. Calculations based on different theoretical models of equilibrium and preequilibrium decay are compared with the experimental results and discussed. Acceptable presentation of the energy behavior of the measured isomeric ratios was obtained when higher angular momentum depletion for preequilibrium emitted particles was included. The absolute values of the isomeric ratios however remain overestimated.We want to express our gratitude to Prof. Ts. Vylov and Dr. V. Brudanin (Dubna) who supplied us with measurement equipment, to Dr. Chr. Necheva for taking part in the experiments, to the U-200 cyclotron staff and to the direction of the Laboratory of Nuclear Reactions (JINR) for making the irradiation possible and to Dr. E. Dobreva (Sofia) for fruitful discussion of the experimental method. We wish to express our gratitude also to Prof. M. Uhl and the NEA data bank for making the computer code STAPRE available to us and to Prof. J. Ernst (Bonn) for fruitful discussions. This project has been completed with the financial support of the Committee for Science at the Council of Ministers under contract No. 644.     

Theoretical calculations of vibrational frequencies and rotational constants of the N2O isotopomers

Theoretical values of vibrational frequencies and rotational constants for all the isotopomers of nitrous oxide are reported. The calculations are carried out variationally using an empirical Morse-cosine potential energy surface previously determined for N₂O, and a set of optimal internal vibrational coordinates. The spectroscopic constants obtained are compared to those extracted from spectroscopic measurements for the , , , , , and isotopomers. The agreement between calculated and observed values for these isotopomers is shown to be excellent, especially for the rotational constants. As a result, an unidentified band recently recorded is properly assigned. The spectroscopic constants computed for the rest of the isotopomers, for which observed information is much scarcer, have therefore a predictive character. The vibrational zero point energies for all the N₂O isotopomers are also given.     

Green's functions for off-shell electromagnetism and spacelike correlations

The requirement of gauge invariance for the Schwinger-DeWitt equations, interpreted as a manifestly covariant quantum theory for the evolution of a system in spacetime, implies the existence of a five-dimensional pre-Maxwell field on the manifold of spacetime and proper time . The Maxwell theory is contained in this theory; integration of the field equations over restores the Maxwell equations with the usual interpretation of the sources. Following Schwinger's techniques, we study the Green's functions for the five-dimensional hyperbolic field equations for both signatures ± [corresponding to O(4, 1) or O(3, 2) symmetry of the field equations] of the proper time derivative. The classification of the Green's functions follows that of the four-dimensional theory for massive fields, for which the mass squared may be positive or negative, respectively. The Green's functions for the five-dimensional field are then given by the Fourier transform over the mass parameter. We derive the Green's functions corresponding to the principal part _P and the homogeneous function ₁ ; all of the Green's functions can be expressed in terms of these, as for the usual field equations with definite mass. In the O(3, 2) case, the principal part function has support for x²², corresponding to spacelike propagation, as well as along the light cone x²=0 (for =0). There can be no transmission ofinformation in spacelike directions, with this propagator, since the Maxwell field, obtained by integration over , does not contain this component of the support. Measurements are characterized by such an integration. The spacelike field therefore can dynamically establish spacelike correlations.     

Coherent Solid-State Phase Transitions with Atomic Diffusion: A Thermomechanical Treatment

Using the framework of modern continuum thermomechanics, we develop sharp- and diffuse-interface theories for coherent solid-state phase transitions. These theories account for atomic diffusion and for deformation. Of essential importance in our formulation of the sharp-interface theory are a system of configurational forces and an associated configurational force balance. These forces, which are distinct from standard Newtonian forces, describe the intrinsic material structure of a body. The configurational balance, when restricted to the interface, leads to a generalization of the classical Gibbs–Thomson relation, a generalization that accounts for the orientation dependence of the interfacial energy density and also for a broad spectrum of dissipative transition kinetics. Our diffuse-interface theory involves nonstandard microforces and an associated microforce balance. These forces arise naturally from an interpretation of the atomic densities as macroscopic parameters that describe atomistic kinematics distinct from the motion of material particles. When supplemented by thermodynamically consistent constitutive relations, the microforce balance yields a generalization of the Cahn–Hilliard relation giving the chemical potentials as variational derivatives of the total free energy with respect to the atomic densities. A formal asymptotic analysis (thickness of the transition layer approaching zero) demonstrates the correspondence between versions of our theories specialized to the case of a single mobile species for situations in which the time scale for interface propagation is small compared to that for bulk diffusion. While the configurational force balance is redundant in the diffuse-interface theory, when integrated over the transition layer, the limit of this balance is the interfacial configurational force balance (i.e., generalized Gibbs–Thomson relation) of the sharp-interface theory.