邮票上的物理学史⑨--牛顿

"牛顿由于发现了万有引力定律而创立了科学的天文学,由于进行了光的分解而创立了科学的光学,由于建立了二项式定律和无穷理论而创立了科学的数学,由于认识了力的本性而创立了科学的力学."恩格斯的这段话很好地总结了牛顿的科学业绩.为了纪念牛顿在科学上的伟大建树,许多国家发行了多枚一套的邮票.     

物理实验开放式教学初探

网上预约实验实现了各校区资源共享、教学内容有弹性满足了不同层次学生的需求，开放式教学增强了教师的责任心，激发了学生学习的主动性和积极性，提高了实验教学质量，充分利用了实验室的资源，取得了较好的效果。     

自由落体实验的改进

针对教材中自由落体实验操作的不稳定性,改进了实验,增强了实验操作的稳定性,提高了实验的精确度,减少了实验次数,节省了时间,提高了课堂效率.     

地磁场测量实验教学设备的改造、替代及软件选取

介绍了周期幅值法测量地磁场的实验方法,指出了原实验设备存在的问题,同时提出了实验设备的改造方案,并详细介绍了如何软选取件模块.该工作降低了实验教学的维护成本,节约了因等待维护耗费的大量时间,保证了实验教学的顺利进行.     

控制环量设计涡轮的实验研究

采用控制环量方法设计了一单级涡轮。该方法打破了传统的设计规律,为验证该方法的可靠性进行了模型试验。在宽广的范围内测定了总特性;在设计点附近作了沿叶高效率分布及动叶进、出口速度三角形的测定。本文给出了主要试验结果并作了简要分析。结果表明基本上达到了设计要求,控制环量设计的主要特征得到了验证,该方法基本可行。     

双波段扫描辐射计的研制

介绍了一种新型小视场、高精度的双波段扫描辐射计。描述了系统的特点,分析了系统的总体方案。介绍了系统的工作原理,对系统的NETD进行了估算,对其探测器的选择、光学系统设计、调制系统设计、扫描机构设计、信号处理等方案进行了详细论述,对系统的标定和测量原理进行了分析,并给出了相应的计算公式。给出了系统的检测结果。     

某空间望远镜相关跟踪系统摆镜随机振动分析

介绍了基础激励下机构随机振动响应的理论与分析方法.利用有限元分析软件ANSYS建立了某空间望远镜相关跟踪系统摆镜的有限元模型,并进行了随机振动响应分析.通过分析考察了其承受动力学环境的能力.对计算结果进行了分析.指出了现有结构中的薄弱环节,提出了改进方案,为摆镜的设计提供了重要参考依据.     

La/酸化膨润土吸附剂的表征与除磷性能

以酸化改性膨润土为载体,采用浸泡法制备了稀土La掺杂的La/酸化膨润土吸附剂.通过XRD和FTIR对其结构进行了表征,探讨了膨润土的改性机理,研究了该吸附剂对废水的除磷性能.结果表明：酸化过程洗掉了膨润土中的杂质和氧化铝,稀土镧的掺杂在膨润土层间及表面引入了一定数量的羟基化合物,改善了膨润土的层间结构并生成了新的La-O-Si键,实现了La与膨润土的复合,提高了膨润土的吸附性能.     

大统一理论:回顾与展望

本文系统地讨论了大统一理论的来龙去脉。回顾了大统一理论的发展历史,讨论了其发展现状及存在问题,指出了进一步发展的方向。本文重点介绍了SU(5)和SO(10)两个模型,讨论了Higgs场、规范等级、渐近自由、重正化等问题。文章进而讨论了一些有趣问题,比如提供了对宇宙重子起源的解释、计算了质子衰变寿命、论述了B-L是否守恒以及讨论了中子和中微子可能有的振荡现象等。     

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提出了一种用于高功率微波武器的等离子体通道天线(PCA),计算了该天线的辐射方向图。推导出了一般性天线的辐射方向函数;建立了PCA的近似电磁模型;给出了圆坐标系下PCA和周围空气中的电磁场,利用边界条件得出了PCA的色散方程,求出PCA的表面波波矢。重点讨论了PCA的辐射场随等离子体密度、天线长度、半径的变化,证实了PCA方向图的可控性。     

On the classical approximation in the quantum statistics of equivalent particles

It is shown here that the microcanonical ensemble for a system of noninteracting bosons and fermions contains a subensemble of state vectors for which all particles of the system are distinguishable. This IQC (inner quantum-classical) subensemble is therefore fully classical, except for a rather extreme quantization of particle momentum and position, which appears as the natural price that must be paid for distinguishability. The contribution of the IQC subensemble to the entropy is readily calculated, and the criterion for this to be a good approximation to the exact entropy is a logarithmically strengthened form of the usual criterion for the validity of classical statistics in terms of the thermal de Broglie wavelength and the average volume per particle. Thus, it becomes possible to derive the Maxwell-Boltzmann distribution directly from the ensemble in the classical limit, using fully classical reasoning about the distinguishability of particles. The entropy is additive—theN! factor of the Boltzmann count cancels out in the course of the calculation, and the N! paradox is thereby resolved. The method of correct Boltzmann counting and the lowest term of the Wigner-Kirkwood series for the partition function are seen to be partly based on the IQC subensemble, and their partly nonclassical nature is clarified. The clear separation in the full ensemble of classical and nonclassical components makes it possible to derive the classical statistics of indistinguishable particles from their quantum statistics in a controlled, explicit way. This is particularly important for nonequilibrium theory. The treatment of molecular collisions along too-literally classical lines turns out to require exorbitantly high temperatures, although there are suggestions of indirect ways in which classical nonequilibrium theory might be justified at ordinary temperatures. The applicability of exact classical ergodic and mixing theory to systems at ordinary temperatures is called into question, although the general idea of coarse-graining is confirmed. The concepts on which the IQC idea is based are shown to give rise to a series development of thermostatistical quantities, starting with the distinguishable-particle approximation.This work was supported in part by the Air Force Office of Scientific Research, through Grants No. AF-AFSOR 557-64 and 557-67.     

Statistical dynamics of the Lorenz model

The dynamics of the Lorenz model in the turbulent regime (r>r _T is investigated by applying methods for treating many-body systems. Symmetry properties are used to derive relations between correlation functions. The basic ones are evaluated numerically and discussed for several values of the parameterr. A theory for the spectra of the two independent relaxation functions is presented using a dispersion relation representation in terms of relaxation kernels and characteristic frequencies. Their role in the dynamics of the system is discussed and it is shown that their numerical values increase in proportion to r. The approximation of the relaxation kernels that represent nonlinear coupling between the variables by a relaxation time expression and a simple mode coupling approximation, respectively, is shown to explain the two different fluctuation spectra. The coupling strength for the modes is determined by a Kubo relation imposing selfconsistency. Comparison with the experimental spectra is made for three values ofr.     

B-spline solver for one-electron Schrödinger equation

A numerical algorithm for solving the one-electron Schrödinger equation is presented. The algorithm is based on the Finite Element method, and the basis functions are tensor products of univariate B-splines. The application of cubic or higher order B-splines guarantees that the searched solution belongs to a continuous and one time differentiable function space, which is a desirable property in the Kohn–Sham equation context from the Density Functional Theory with pseudopotential approximation. The theoretical background of the numerical algorithm is presented, and additionally, the implementation on parallel computers with distributed memory is described. The current implementation of the algorithm uses the MPI, HYPRE and ParMETIS libraries to distribute matrices on processing units. Additionally, the LOBPCG algorithm from HYPRE library is used to solve the algebraic generalized eigenvalue problem. The proposed algorithm works for any smooth interaction potential, where the domain of the problem is a finite subspace of the ?³ space. The accuracy of the algorithm is demonstrated for a selected interaction potential. In the current stage, the algorithm can be applied to solve the linearized Kohn–Sham equation for molecular systems.     

On the dynamics and ergodic properties of theXY model

The return to equilibrium is investigated for one-dimensional (one-sided) chain of theXY model. The initial state is taken to be the Gibbs state for the sum of the Hamiltonian for theXY model of lengthN and a perturbation by a uniform magnetic field acting on the firstn sites. The time evolution under the unperturbedXY model Hamiltonian is studied for the expectation value of the average magnetization of the same firstn sites in the infinitely extended system (i.e., after taking the limitN). It is found that the return to equilibrium occurs for a finite-size perturbation (i.e., for a fixedn), while it does not occur for an infinite-size perturbation (i.e., the limit n is taken simultaneously as N). A certain twisted asymptotic Abelian property of theXY model is shown and used as a technical tool.     

Correlations and conductivity of interacting fermions in a disordered chain—a Monte Carlo simulation

The interplay between disorder and interaction in a one dimensional system of fermions is investigated by the use of a Monte Carlo simulation. The model considered (Hubbard Anderson Model) is a combination of the Anderson model, for noninteracting fermions in a random potential, and the extended Hubbard model, for interacting fermions in a periodic potential. To study the physics of this model, a (Quantum) Monte Carlo simulation is performed for a finite chain of 120 sites. The simulation is done for different band fillings, and several values of the interaction parameters and the strength of disorder. The low frequency behaviour of the conductivity is calculated as well as the static correlation functions for the charge density and the spin density. From the results for these quantities the competition between disorder-induced effects (Anderson localization) and interaction-induced effects (Mott transition, long range order) is studied.     

Radon in water from Transylvania (Romania)

Radon is a radioactive noble gas of a natural origin that may be found anywhere in soil, air and in different types of water: surface, well and spring. It is worth to carry out surveys for the radon in natural waters for radiation protection as well as for geological considerations. The results present here are from a survey carried out in the Transylvania region in Romania for radon concentrations in natural waters. The measurements were made using the LUK-VR system that is based on radon gas measurement with Lucas cell. Due to the large number of water samples (1511 samples) collected for analysis, a short counting time had to be used, so that the measurements were made during the non-equilibrium state between radon and its progeny. The results show that the radon concentrations are within the range of $0.5–129.3\mathrm{kBq}/{\mathrm{m}}^3$ with an average value of $15.4\mathrm{kBq}/{\mathrm{m}}^3$ for all types of water covered within this survey.     

On testing objective local theories by using Greenberger-Horne-Zeilinger states

The convenience of using Greenberger-Horne-Zeilinger (GHZ) stales for disproving a recently proposed hardest-to-beat type of hidden variables theory is analyzed. The experimental conditions for observing a discrepancy from quantum mechanical predictions are obtained, for a GHZ state with an arbitrary number q of particles. It is shown that an Orsay-like experiment is preferable, even for highly idealized conditions and even if the difficulty of preparation of a GHZ state with a large number of particles is not taken into account. The situation may be different for the case q=4 if a proposed theorem is demonstrated true.     

Model basis states for photons and "empty waves"

From the perspective of physical realism (PR), a photon is a localized entity that carries energy and momentum, and which is surrounded by a wave packet (anempty wave) that is devoid of observable energy or momentum. In creating quantized PR basis states for a photon wave packet, three requirements must be met:(1) The basis states must each carry the frequency of the wave;(2) They must closely resemble the photon, so that e.g. they scatter in the same manner from an optical mirror;(3) They must have infinitesimal energy, linear momentum, and angular momentum. An essentially zero-energy "empty wave" quantum-a "zeron"-is defined which meets these requirements. It is created as an asymmetric single-particle (or single-antiparticle) excitation of the vacuum state, with the "particle" (or "antiparticle") and its associated "hole" (or "antihole") forming a rotational bound state. The photon is reproduced as a symmetric particle-antiparticle excitation of the vacuum state, with the "particle" and "antiparticle" also forming a rotational bound state. The relativistic transformation problem is discussed. A key point in this development is the deduction of the correct equation of motion for a "hole" state in an external electrostatic field.     

Determination of Microwave Parameters of Isotropic Mediums by Using an Open Quasi-Optical Spherical Resonator

The technique for determination of dielectric parameters of substances is submitted on a base of using a high-Q whispering gallery oscillations in a quasi-optical spherical resonator. The function ability of a method is shown on an example of measurement of permittivity for several substances in the 8 mm wave band.