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1.
物理教学离不开理想化模型的建构,简化的理想模型能够帮助中学生在现有知识层面的基础上,更好地理解相关知识并解决问题.但是在实际物理问题中,如果不充分考虑理想化条件,学生在解决问题时就容易产生认知矛盾,不知所措.以一个有趣的静电场问题为例,揭示理想化模型的局限性,强调"去理想化"思维习惯的重要性.探讨分析了教师如何帮助学生打破思维定势,让其对已掌握的物理知识活学活用,培养学生严谨的科学思维.  相似文献   
2.
This paper investigated the effect of Gaussian distribution width, average particle diameter, particle loading, and the tapered angle on minimum fluidization velocity (Umf) by conducting extensive experiments in tapered fluidized beds. Three powders with Gaussian size distribution and different distribution widths were used in the experiments. An increase in Umf with increasing the average particle diameter, particle loading, and the tapered angle was observed. There was also a nonmonotonic behavior of Umf as the Gaussian distribution width increased. An empirical correlation including dimensionless groups for predicting Umf in tapered beds was developed in which the effect of distribution width was considered. The proposed correlation predictions were in good agreement with the experimental data, with a maximum deviation of 16.5% and average and standard deviations of, respectively, 6.4% and 7.4%. The proposed correlation was also compared with three earlier models, and their accuracy was discussed.  相似文献   
3.
张琳蕊  徐祯  张萍 《物理通报》2022,(1):47-49+53
关于显像管电视机的成像原理,高中物理教材仅关注运动的带电粒子在偏转线圈提供的磁场中的偏转.但在实际生活中,地磁场也会对电视机显像管中运动带电粒子的轨迹产生影响.本文立足于高中生的认知能力,从生活实例出发,分析地磁场对彩色显像管成像的影响,细化建模过程,给出真实参数,凸显科学研究方法在教学中的应用,使教学内容与现代科技和生活实际相联系,从而将培养学生的核心素养落实在日常教学之中.  相似文献   
4.
Qian Dong 《中国物理 B》2022,31(3):30303-030303
Using a single-mode approximation, we carry out the entanglement measures, e.g., the negativity and von Neumann entropy when a tetrapartite generalized GHZ state is treated in a noninertial frame, but only uniform acceleration is considered for simplicity. In terms of explicit negativity calculated, we notice that the difference between the algebraic average $\pi_{4}$ and geometric average $\varPi_{4}$ is very small with the increasing accelerated observers and they are totally equal when all four qubits are accelerated simultaneously. The entanglement properties are discussed from one accelerated observer to all four accelerated observers. It is shown that the entanglement still exists even if the acceleration parameter $r$ goes to infinity. It is interesting to discover that all 1-1 tangles are equal to zero, but 1-3 and 2-2 tangles always decrease when the acceleration parameter $r$ increases. We also study the von Neumann entropy and find that it increases with the number of the accelerated observers. In addition, we find that the von Neumann entropy $S_{\text{ABCDI}}$, $S_{\text{ABCIDI}}$, $S_{\text{ABICIDI}}$ and $S_{\text{AIBICIDI}}$ always decrease with the controllable angle $\theta$, while the entropies $S_{3-3~\rm non}$, $S_{3-2~\rm non}$, $S_{3-1~\rm non}$ and $S_{3-0~\rm non}$ first increase with the angle $\theta$ and then decrease with it.  相似文献   
5.
惯性约束核聚变研究最近取得可喜成果,美国国家点火装置NIF装置实验上聚变增益达到了输入激光能量的三分之二.但是,这一成果与人们的预期还有较大差距,需要更深入研究激光与等离子体相互作用初期的动力学过程.我们发展了一种新方法,用单发长脉冲电子束团为探针,测量激光等离子体内电磁场在整个等离子体持续时间内的演化过程.实验中,高压静电电子源产生能量0—100 keV连续可调、脉宽10ns的电子束团.1 J,532 nm,脉宽约4 ns的激光脉冲聚焦到银靶上,激发产生等离子体.电子束团穿过激光等离子体,被其中的电磁场调制后成像,单发电子束团时间宽度会覆盖整个等离子体持续时间,通过分析电子束团的调制强度,推得等离子体内电磁场的变化.实验上成功实现了单发电子束团对整个激光等离子体内电场的诊断测量,获得了演化曲线,推算出实验条件下电子束通过路径上平均电场的最大值约为7.74×10~5 V/m.  相似文献   
6.
In the present study, a specific and sensitive approach using ultra-high-performance liquid chromatography coupled with triple quadrupole tandem mass spectrometry was developed and validated for the quantitative analysis of 14 constituents in rat plasma, liver, and heart. The method was fully validated and successfully applied to pharmacokinetic, hepatic disposition, and heart tissue distribution studies of 14 compounds after the oral administration of Qi-Li-Qiang-Xin capsule. Ginsenoside Rb1, alisol A, astragaloside IV, and periplocymarin were found to be highly exposed in rat plasma, while toxic components such as hypaconitine, mesaconitine, and periplocin had low circulation levels in vivo. Moreover, sinapine thiocyanate, neoline, formononetin, calycosin, and alisol A exhibited significant liver first-pass effects. Notably, high levels of alisol A, periplocymarin, benzoylmesaconine, and benzoylhypaconine were observed in the heart. Based on high exposure and appropriate pharmacokinetic features in the systemic plasma and heart, astragaloside IV, ginsenoside Rb1, periplocymarin, benzoylmesaconine, benzoylhypaconine, and alisol A can be considered as the main potentially effective components. Ultimately, the results provide relevant information for discovery of effective substances, as well as further anti-heart failure action mechanism investigations of Qi-Li-Qiang-Xin capsule.  相似文献   
7.
试验发现,以球形TNT为中心爆源,球形玻璃珠构成的颗粒和球壳中发生破碎的颗粒体积分数随当量比(颗粒球壳的质量与TNT炸药的质量比)的增加呈现指数衰减规律。采用有限元与离散元耦合的连续非连续数值方法,揭示了中心炸药起爆后颗粒环壳内爆炸波的传播衰减和在环壳外界面反射后的稀疏卸载过程。由于爆炸波的短脉冲特性,颗粒内部应力场始终处于应力非均衡状态,采用应力均衡状态下颗粒破碎强度的Weibull分布会得到远高于试验测得的破碎颗粒体积分数。因此采用破坏波传播特征时间内的平均诱导应力而非瞬时诱导应力作为颗粒破碎强度的应力指标,并通过试验结果确定破坏波传播特征时间。考虑了应力传播的非均匀性对于颗粒破碎的影响,得到了平均诱导应力峰值的概率分布随比例距离的变化规律,结合修正后的颗粒破碎强度Weibull分布建立了破碎颗粒体积分数随比例距离的变化模型。  相似文献   
8.
9.
黄孝龙  李宁  翁春生  康杨 《中国物理 B》2022,31(1):14703-014703
Instantaneous and precise velocity sensing is a critical part of research on detonation mechanism and flow evolution.This paper presents a novel multi-projection tunable diode laser absorption spectroscopy solution,to provide a real-time and reliable measurement of velocity distribution in detonation exhaust flow with obvious nonuniformity.Relations are established between overlapped spectrums along probing beams and Gauss velocity distribution phantom according to the frequency shifts and tiny variations in components of light-of-sight absorbance profiles at low frequencies analyzed by the fast Fourier transform.With simulated optical measurement using H2O feature at 7185.6 cm-1 carried out on a phantom generated using a simulation of two-phase detonation by a two-fluid model,this method demonstrates a satisfying performance on recovery of velocity distribution profiles in supersonic flow even with a noise equivalent absorbance up to 2×10-3.This method is applied to the analysis of rapidly decreasing velocity during a complete working cycle in the external flow field of an air-gasoline detonation tube operating at 25 Hz,and results show the velocity in the core flow field would be much larger than the arithmetic average from traditional tunable diode laser doppler velocimetry.This proposed velocity distribution sensor would reconstruct nonuniform velocity distribution of high-speed flow in low cost and simple operations,which broadens the possibility for applications in research on the formation and propagation of external flow filed of detonation tube.  相似文献   
10.
Transferring entangled states between matter qubits and microwave-field (or optical-field) qubits is of fundamental interest in quantum mechanics and necessary in hybrid quantum information processing and quantum communication. We here propose a way for transferring entangled states between superconducting qubits (matter qubits) and microwave-field qubits. This proposal is realized by a system consisting of multiple superconducting qutrits and microwave cavities. Here, „qutrit” refers to a three-level quantum system with the two lowest levels encoding a qubit while the third level acting as an auxiliary state. In contrast, the microwave-field qubits are encoded with coherent states of microwave cavities. Because the third energy level of each qutrit is not populated during the operation, decoherence from the higher energy levels is greatly suppressed. The entangled states can be deterministically transferred because measurement on the states is not needed. The operation time is independent of the number of superconducting qubits or microwave-field qubits. In addition, the architecture of the circuit system is quite simple because only a coupler qutrit and an auxiliary cavity are required. As an example, our numerical simulations show that high-fidelity transfer of entangled states from two superconducting qubits to two microwave-field qubits is feasible with present circuit QED technology. This proposal is quite general and can be extended to transfer entangled states between other matter qubits (e.g., atoms, quantum dots, and NV centers) and microwave- or optical-field qubits encoded with coherent states.  相似文献   
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