机械能守恒定律和相对性原理

详细阐述了机械能守恒定律成立的条件及该定律服从力学相地性原理所需满足的条件,回答了《河北师范学院学报（自然科学版）》在１９９７年第２期上赵佩章等同志对本刊多年来氯表的有关文章的批评     

机械能守恒定律服从力学相对性原理

阐述了机械能守恒定律服从力学相对性原理。     

"机械能守恒定律是否遵从相对性原理"辨

从两个层次上的相对性原理出发,对“机械能守恒定律是否遵从相对性原理”进行了剖析;并对究竟把什么称作机械能守恒定律更为合理,提出了一些看法。     

力学相对性原理与机械能

本文指出，只包括内势能的机械能定理和机械 能守恒定律满足力学相对性原理．但是，包括稳定外 势能的机械能定理和机械能守恒定律是不满足力学相对性原理的．机械能守恒定律是否满足力学相对性原理，取决于对势能的处理方法，与力学系统受力状态和机械能守恒条件的表述方式无关     

势能和机械能守恒定律

本文讨论了单质点和质点系的机械能守恒问题，指出只有内保守力的孤立系统，才满足力学相对性原理．     

质点系的功能原理和机械能守恒定律的讨论

我们使用的教材在推导质点系的功能原理时，将质点系的动能定理：     

动量守恒定律与机械能守恒定律

问题的提出在力学中,我们学习到两条最基本、最重要的定律,就是:动量守恒定律与机械能守恒定律,这两定律属于经验定律;它们的建立是从许多学者们长时期的实验事实概括出来的。因此,初学物理的人们很自然地就会认为这两定律在力学中是无处而不可以应用的。但是,     

非惯性系机械能守恒定律

从非惯性系动力学方程出发，可导出对非惯性系的动能定理，在此基础上，引进惯性力势能Ｕｈ及对非惯性系的机械能 Ｅ’＝Ｕ’＋Ｕｈ＋Ｔ’，又可导出质点对非贯性系的机械能守恒律．此守恒律用来求解某些相对运动问题极为简便．     

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.     

对一道力学习题解法的剖析

通过一道经典的力学习题的分析,考察内力的不同作用效果,指出加深理解物理规律适用条件的重要性.     

机械能守恒定律及动量守恒定律演示仪器的制作

制作一种可以同时验证机械能守恒和动量守恒的实验装置,并通过这两个实验现象的对比更显著地体现了两个实验的物理现象与原理,有利于学生对机械能守恒与动量守恒原理的理解与认知。     

Enhancement of Optomechanical Squeezing of Light Using the Optical Coherent Feedback

A coherent feedback scheme is used to enhance the degree of squeezing of the output field in a cavity optomechanical system. In the feedback loop, a beam splitter (BS) plays the roles of both a feedback controller and an input–output port. To realize effective enhancement, the output quadrature should take the same form as the input quadrature, and the system should operate at the deamplification situation in the meantime. This can be realized by choosing an appropriate frequency-dependent phase angle for the generalized quadrature. Additionally, both the transmissivity of the BS and the phase factor induced by time delays in the loop affect optical squeezing. For the fixed frequency, the optimal values of transmissivity and phase factor can be used to achieve the enhanced optical squeezing. The effect of optical losses on squeezing is also discussed. Optical squeezing is degraded by the introduced vacuum noise owing to the inefficient transmission in the loop. We show that the enhancement of squeezing is achievable with the parameters of the current experiments.     

AlN在AlN/VN纳米多层膜中的相转变及其对薄膜力学性能的影响

采用反应磁控溅射制备了AlN/VN纳米多层膜.研究了多层膜调制周期对AlN生长结构的影响以 及纳米多层膜的力学性能.结果表明：小周期多层膜中的AlN以亚稳的立方相(c-AlN)存在并 与VN形成共格外延生长的超晶格.薄膜产生硬度和弹性模量升高的超硬效应.大调制周期下， AlN从立方结构转变为稳定的六方相（h-AlN），并使多层膜形成纳米晶的“砖墙”型结构. 讨论认为VN的模板作用有利于c-AlN的生长，但不能显著提高其临界厚度. 关键词： 薄膜的力学性能 外延生长 亚稳相     

Effect of Addition of Process Control Agent (PCA) on the Nanocrystalline Behavior of Elemental Silver during High Energy Milling

Mechanical Alloying (MA) or High Energy Milling has been a subject of great interest for last few decades. However, in the majority of the cases the investigations are confined to areas like alloying in binary or multi-component systems from premixed powders. Very little work has been reported on high-energy milling of pure metals. There are some reports on mechanical alloying of pure metals that undergo polymorphic transformation on milling, but relatively few papers have been reported in the literature pertaining to attrition milling of pure metals, which do not fall under this category. One such attempt has been made in this investigation by subjecting a noble metal like silver with fcc crystal structure to attrition milling. The present work deals with the investigation of the effect of addition of a process control agent (PCA) on the nanocrystalline behavior of elemental silver powder subjected to high energy milling in an attritor. Elemental silver powder was subjected to attrition milling with and without addition of stearic acid as PCA. The powder samples drawn at periodic intervals during the course of milling were subjected to characterization using techniques like XRD, SEM and DSC. The variation in particle shape morphology, crystallite size and lattice strain as a function of PCA was studied.     

非Chetaev型非完整可控力学系统的Noether-形式不变性

基于函数对时间的全导数采用沿系统的运动轨线方式, 研究非Chetaev型非完整可控力学系统的Noether-形式不变性. 给出非Chetaev型非完整可控力学系统的Noether-形式不变性的定义和判据. 由Noether-形式不变性同时得到了Noether守恒量和新型守恒量. 并举例说明结果的应用. 关键词： 非Chetaev型非完整系统 可控力学系统 Noether-形式不变性 守恒量     

Equation of state and temperature variation of the bulk modulus of the alkaline earth fluorides

The isotherms for the alkaline earth fluorides (CaF₂, SrF₂ and BaF₂) have been computed using the expression for the total free energy of a crystal in the quasiharmonic approximation. The theoretical points for SrF₂ and BaF₂ have been compared with the points derived from Bridgman’s experimental relation. The temperature variation of the isothermal bulk modulus of the alkaline earth fluorides has been worked out on the basis of Axe’s shell model. The theoretica points are compared with the points obtained from the temperature variation of the elastic constants data. It is found that the vibrational contribution to the temperature variation of the elastic constants in these crystals is significant.