构建 “三三三”混合式课堂教学新模式*——以“原子结构”类比模型的建构为例(Ⅱ)

根据优化的无机化学“原子结构”教学设计,运用一系列直观具体的原子结构类比模型,开展了“三三三”混合式课堂教学改革。通过比较改革前后的教学效果及问卷调查结果,发现试点班学生的主动性、积极性和参与性有明显提高,教学改革达到了预期效果。结果表明,在课堂中渗透类比思维,是帮助学生理解抽象概念和理论的有效方法。     

李萨如图激光扫描模拟机理分析

对李萨如图激光扫描模拟机理进行理论分析．其结论是：两个以不同频率相互垂直简谐振动的反射镜，将定向入射的激光光束转化为同时在两个相互垂直方向上散射的激光束，且相应两个方向的散射角分别依两镜片简谐振动的规律变化，这种散射激光束照射在演示屏上光斑的运动轨迹便是李萨如图的模拟。     

对偶定理在三角教与学中的应用

数理逻辑中的对偶定理在计算中已经有广泛的应用，笔用对偶定理作为指导思想在三角证明题的构造，在条件等式的证明和三角化简求值中都有广泛的应用。可见对定理可以开拓研究领域，还可以使研究的三角题扩大一倍，更可以创造更多的三角题。     

Computation of internal aerodynamic noise from a quick-opening throttle valve using frequency-domain acoustic analogy

Recently, plastic products in air-intake parts of automotive engines have become very popular due to advantages that include reduced weight, constricted cost, and lower intake air temperature. However, flow-induced noise in air-intake parts becomes a more serious problem for plastic intake-manifolds than for conventional aluminum-made manifolds. This is due to the fact that plastic manifolds transmit more noise owing to their lower material density. Internal aerodynamic noise from a quick-opening throttle valve is computed by using a frequency-domain acoustic analogy, which is based on the integral formula derived by using the General Green Function, Lighthill’s acoustic analogy and Curle’s extension of Lighthill’s. The integral formula is arranged in such a manner that allows a frequency-domain acoustic signal to be predicted at any location in a duct through the use of unsteady flow data in space and time, which can be obtained by applying Computational Fluid Dynamics techniques. The prediction of the acoustic pressure level from the quick-opening throttle valve shows good agreement with actual measurement. Through the detailed analysis of the flow-noise generation mechanism it was found that the anti-vortex lines, formed behind the throttle valve during the quick-opening behavior, feed the large-scale coherent turbulence and, as a result, play a crucial role in generating the dipolar sound from unsteady loading of the quick-opening throttle valve. From this, it can be inferred that the low-noise design of the throttle-duct system can be made by using this concept to break the large-scale vortex structure.     

Reactivity of [Os3(CO)10(NCMe)2] and [Os3(CO)10(μ-Cl)(μ-AuPPh3)] with 4-mercaptopyridine: X-ray structure of [Os3(CO)10(μ-H)(μ-SC5H4N)] and [Os3(CO)10(μ-AuPPh3)(μ-SC5H4N)]

The compound [Os₃(CO)₁₀(μ-Cl)(μ-AuPPh₃)] (2) was prepared from the reaction between [Os₃(CO)₁₀(NCMe)₂] (1) and [AuClPPh₃] under mild conditions. The reaction of 2 with 4-mercaptopyridine (4-pyS) ligand yielded compounds [Os₃(CO)₁₀(μ-H)(μ-SC₅H₄N)] (4), formed by isolobal replacement of the fragment [AuPPh₃]⁺ by H⁺ and [Os₃(CO)₁₀(μ-AuPPh₃)(μ-SC₅H₄N)] (5). [Os₃(CO)₁₀(μ-H)(μ-SC₅H₄N)] (4) was also obtained by substitution of two acetonitrile ligands in the activated cluster 1 by 4-pyS, at room temperature in dichloromethane. Compounds 2-5 were characterized spectroscopically and the molecular structures of 4 and 5 in the solid state were obtained by single crystal X-ray diffraction studies.     

利用特殊函数和类比法有序化排列正负指数幂算符

研究算符函数的有序化排列是一项重要的数理任务.本文利用特殊函数和正规乘积排序与反正规乘积排序间的互换法则法导出了幂算符(αα^+)^±n和(α^+α)^±n的正规与反正规乘积排序.进一步,利用类比法得到了算符(XP)^±n和(PX)^±n的坐标-动量排序与动量-坐标排序式.最后,对新得到的这些算符结果的应用进行一些讨论.     

光纤传感器在相似材料模型测试中的相容性研究

为了找出光纤传感器弯曲损耗与岩层变形破坏过程中变形的关系 ,在相似材料模型铺设过程中将光纤传感器埋入在层合材料之间。研究了相似材料模拟实验中 ,光纤与模型岩层的相互作用机理 ,光纤与模型岩层的相容性 ,以及提高二者相容性的方法 ;并设计了一种基于光时域反射技术的新型微弯光纤传感器 ,用于相似材料模型的应变、位移检测中。实验研究表明 ,这种传感器结构不仅能实现对岩体变形的监测 ,而且在该情况下传感器不会失效 ,具有较好的相容性。构建了岩体光纤检测的理论基础     

Gas-dynamic analogy in the theory of stratified liquid flows with a free boundary

Novel approximate mathematical models of long-wave theory describing flows of a density-stratified liquid with a free boundary are proposed. It is shown that in certain cases the equations of the novel models coincide with either the equations of nonisentropic gas dynamics with a polytropic equation of state for γ = 2 or the equations describing the dynamics of a mixture of two perfect gases.     

Gas-dynamic analogy for vortex free-boundary flows

The classical shallow-water equations describing the propagation of long waves in flow without a shear of the horizontal velocity along the vertical coincide with the equations describing the isentropic motion of a polytropic gas for a polytropic exponent γ = 2 (in the theory of fluid wave motion, this fact is called the gas-dynamic analogy). A new mathematical model of long-wave theory is derived that describes shear free-boundary fluid flows. It is shown that in the case of one-dimensional motion, the equations of the new model coincide with the equations describing nonisentropic gas motion with a special choice of the equation of state, and in the multidimensional case, the new system of long-wave equations differs significantly from the gas motion model. In the general case, it is established that the system of equations derived is a hyperbolic system. The velocities of propagation of wave perturbations are found. __________ Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 48, No. 3, pp. 8–15, May–June, 2007.     

浅谈物理学研究和应用中的类比法

在物理学的方法论中，类比法是一种逻辑思维方法，也是一种重要的创新思维方式．本文根据其原则介绍了类比法在以下四个方面的运用：物理学研究、物理模型和概念提出、建立物理理论、物理教学．