质点系的功能原理和机械能守恒定律不应忽视的条件

针对质点系功能原理及机械能守恒定律的推导过程,进行了分析,提出了适用条件.     

机械能守恒定律成立的条件

1功能原理与机械能守恒定律 对于质点系从一个状态变化到另一个状态的过程，根据质点的动能定理可以得到质点系动能定理．而由质点系动能定理又能导出功能原理，功能原理的表述为 A外力＋A非保守内力=△E（1） 式中A外力为外力所做的功，A非保守内力为非保守内力所做的功，△E为系统机械能E的增量．     

势能引入的一种方法

本文给出了适合工科大学物理教学的势能引入的一种方法     

跑步运动的力学探究

用质心运动定律与平动功和形变功知识分析跑步的动力来源,探究内力与外力之间的关系,强调"许多自主运动系统的质心平动是系统内力引起的外力做功的结果".     

人走路时摩擦力是否做功

阐明人走路时，摩擦力没有做功，但摩擦力起了将内能转化为质心平动动能的作用。     

质点系内外力做功的物理图像分析

为了澄清质点系内外力做功分析中常见的错误, 通过详细分析一道典型的易错题目, 比较清晰地建立 了类似物理情景下质点系内外力做功的物理图像     

浅析质点系动量定理中“∑”的位置

质点系动量守恒定律是从质点系动量定理中推导得出的,而质点系动量定理的表达中关于质点系受到的总冲量却有两种表示,为了使质点系动量守恒定律的推导更自然,“∑”在质点系动量定理的表达式中就应该在“∫”内而不应该在“∫”外。     

Calorimeter energy calibration using the energy conservation law

A new calorimeter energy calibration method was developed for the proposed ILC detectors. The method uses the center-of-mass energy of the accelerator as the reference. It has been shown that using the energy conservation law it is possible to make ECAL and HCAL cross calibration to reach a good energy resolution for the simple calorimeter energy sum.      

Discussion of the He-He interaction energy in the average energy approximation

Using the Unsöld average energy method a double perturbation theory expression for the interaction energy through second order is obtained which includes intra-atomic correction terms arising from the use of trial wavefunctions to represent the non-interacting molecules. These formal expressions are applied to the ground state He-He interaction and results for the interaction energy are obtained that compare favourably with recent semiempirical and ab initio calculations. The Unsöld calculations are used to investigate approximations that have been introduced into the average energy calculation by other workers, and as a model for discussing the relative importance of second-order charge overlap and exchange effects and the convergence of the multipole treatment of the interaction energy for this typical non-bonded interaction. The results illustrate the importance of knowing as many terms as possible in the R ^-1 expansion of the energy. Finally a portion of this work required the recalculation of the He-He repulsive energy obtained by using the Eckart wavefunction to represent the helium atom. The resultant energy is approximately 25 per cent lower than that previously obtained using this wavefunction for most values of R.     

The fractal energy measurement and the singularity energy spectrum analysis

The singularity exponent (SE) is the characteristic parameter of fractal and multifractal signals. Based on SE, the fractal dimension reflecting the global self-similar character, the instantaneous SE reflecting the local self-similar character, the multifractal spectrum (MFS) reflecting the distribution of SE, and the time-varying MFS reflecting pointwise multifractal spectrum were proposed. However, all the studies were based on the depiction of spatial or differentiability characters of fractal signals. Taking the SE as the independent dimension, this paper investigates the fractal energy measurement (FEM) and the singularity energy spectrum (SES) theory. Firstly, we study the energy measurement and the energy spectrum of a fractal signal in the singularity domain, propose the conception of FEM and SES of multifractal signals, and investigate the Hausdorff measure and the local direction angle of the fractal energy element. Then, we prove the compatibility between FEM and traditional energy, and point out that SES can be measured in the fractal space. Finally, we study the algorithm of SES under the condition of a continuous signal and a discrete signal, and give the approximation algorithm of the latter, and the estimations of FEM and SES of the Gaussian white noise, Fractal Brownian motion and the multifractal Brownian motion show the theoretical significance and application value of FEM and SES.     

Finding the dominant energy transmission paths in statistical energy analysis

A key issue for noise, vibration and harshness purposes, when modelling the vibroacoustic behaviour of a system, is that of determining how energy is transmitted from a given source, where external energy is being input, to a target where energy is to be reduced. In many situations of practical interest, a high percentage of the transmitted energy is driven by a limited set of dominant paths. For instance, this is at the core of the existence of transmission loss regulations between dwellings. In this work, it is shown that in the case of a system modelled with statistical energy analysis (SEA), the problem of ranking dominant paths can be posed as a variation of the so-called K shortest path problem in graph theory. An algorithm for the latter is then modified and adapted to obtain the sorted set of K dominant energy transmission paths in a SEA model. A numerical example to show its potential for practical applications is included.     

能量追踪

在非惯性系中讨论能量的传递时,需考虑惯性力的功。     

Electric ignition energy evaluation and the energy distribution structure of energy released in electrostatic discharge process

Ignition energy is one of the important parameters of flammable materials, and evaluating ignition energy precisely is essential to the safety of process industry and combustion science and technology. By using electric spark discharge test system, a series of electric spark discharge experiments were conducted with the capacitor-stored energy in the range of 10 J, 100 J, and 1000 J, respectively. The evaluation method for energy consumed by electric spark, wire, and switch during capacitor discharge process has been studied respectively. The resistance of wire, switch, and plasma between electrodes has been evaluated by different methods and an optimized evaluation method has been obtained. The electric energy consumed by wire, electric switch, and electric spark-induced plasma between electrodes were obtained and the energy structure of capacitor-released energy was analyzed. The dynamic process and the characteristic parameters(the maximum power, duration of discharge process) of electric spark discharge process have been analyzed. Experimental results showed that, electric spark-consumed energy only accounts for 8%–14% of the capacitor-released energy. With the increase of capacitor-released energy, the duration of discharge process becomes longer, and the energy of plasma accounts for more in the capacitor-released energy. The power of electric spark varies with time as a damped sinusoids function and the period and the maximum value increase with the capacitor-released energy.     

Effect of Wigner energy on the symmetry energy coefficient in nuclei

The nuclear symmetry energy coefficient(including the coefficient a_(sym)~((4)) of the I~4 term) of finite nuclei is extracted by using the differences of available experimental binding energies of isobaric nuclei.It is found that the extracted symmetry energy coefficient a_(sym)~*(A,I) decreases with increasing isospin asymmetry I,which is mainly caused by Wigner correction,since e_(sym)~* is the summation of the traditional symmetry energy e_(sym) and the Wigner energy ew.We obtain the optimal values J = 30.25±0.10 MeV,a_(ss)=56.18±1.25 MeV,a_(sym)~((4)) = 8.33±1.21 MeV and the Wigner parameter x= 2.38 ±0.12 through a polynomial fit to 2240 measured binding energies for nuclei with20 ≤ A ≤ 261 with an rms deviation of 23.42 keV.We also find that the volume symmetry coefficient J■ 30 MeV is insensitive to the value x,whereas the surface symmetry coefficient a_(ss) and the coefficient a_(sym)~((4)) are very sensitive to the value of x in the range 1≤x≤4.The contribution of the a_(sym)~((4)) term increases rapidly with increasing isospin asymmetry I.For very neutron-rich nuclei,the contribution of the a_(sym)~((4)) term will play an important role.     

能量公设与自由能判据的普遍化形式

从能量公设的角度论述了自由能及其判据的普遍化形式,并对其本质内涵进行了讨论．讨论认为：热力学系统中目由能的一般形式是与N种功类型相关的各种能形式之和,对孤立物体系在温度不变的情形下,不可逆过程总是导致总自由能的减少．通过实例说明了普遍化形式自由能判据的应用．     

Nature of the energy dependent self energy for photoelectrons in copper

New high resolution ultraviolet photoemission energy distributions (EDCs) from copper are found to agree best with the calculations of Williams et al., using the Chodorow potential, if an energy dependent shift is made between the experimental and calculated EDCs. It is argued that this shift is most probably due to an energy dependent self energy as discussed by Lundqvist and others.