讲透一个模型 领会一种方法 发散一串问题——从一道电磁感应的典型例题谈高考一轮复习中的发散式教学

高考一轮复习的一个主要目标就是对基本解题方法的理解和掌握.因此一轮复习课中的发散式教学不宜覆盖太多的知识点,而应紧紧抓住某一模型的物理背景,引导学生深入探讨该模型的特点和规律.在此基础上再针对性地发散以提高学生举一反三的应变能力,即"讲透一个模型,领会一种方法,发散一串问题".     

SHOCK COMPRESSION BEHAVIOR OF BROMOFORM

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Use of a lensed fiber for a large-field-of-view, high-resolution, fiber-scanning microendoscope

We report the application of a lensed fiber to a miniaturized fiber raster scanner in order to reduce the fiber's output beam size, thereby allowing for a compact and flexible endoscope capable of a large field of view (FOV) and high spatial resolution. For a proof of principle, the fabricated lensed fiber scanner is paired with a miniaturized gradient-index assembly to achieve a one-photon lateral resolution of 1.1 μm with a FOV that has a diameter of 440 μm.     

Production of a Large, Quiescent, Magnetized Plasma

This paper describes an experimental device which produces a large, homogeneous, quiescent, and magnetized plasma. Typical numbers as measured in an Argon plasma are: Size - 6 cm diameter × 100 cm length; Density - 108 to 1010 electrons/cm3; Electron temperature - 1 to 3 e. v.; Noise fluctuation - e?f1/kBTe < 5%; Magnetic field - to 5 kG.     

Coupling a quantum dot, fermionic leads, and a microwave cavity on a chip

We demonstrate a hybrid architecture consisting of a quantum dot circuit coupled to a single mode of the electromagnetic field. We use single wall carbon nanotube based circuits inserted in superconducting microwave cavities. By probing the nanotube dot using a dispersive readout in the Coulomb blockade and the Kondo regime, we determine an electron-photon coupling strength which should enable circuit QED experiments with more complex quantum dot circuits.     

Threshold, power, and spectral characteristics of a semiconductor emitter with a fiber Bragg grating

The threshold, power, and spectral characteristics of an emitter with a fiber Bragg grating are calculated. The effect of heating of the active region of a laser diode, its thermal resistance, and radiation power extracted from the cavity of the emitter on these characteristics is investigated. It is shown that satisfactory agreement between the theory and experiment is observed when the heating of the active zone of the laser diode by the pump current flowing through it and the radiation power extracted from the cavity of the emitter are taken into account.     

Influence of sonication,temperature, and agitation,on the physical properties of a palm-based fat crystallized in a continuous system

High-intensity ultrasound (HIU) has been used in the past to change fat crystallization and physical properties of fat crystalline networks. The objective of this work was to evaluate how HIU placed on different positions in a scraped surface heat exchanger (SSHE) using different processing conditions affect the physical properties of an interesterified palm olein. The sample was crystallized at two temperatures (20 °C and 25 °C) and two agitation rates (344/208 rpm and 185/71 rpm, barrels/pin worker). HIU (12.7 mm-diameter tip, 50% amplitude, 5 s pulses) was placed at three different positions within the SSHE. After processing, samples were stored at 25 °C for 48 h and analyzed according to the crystal morphology, solid fat content (SFC), oil binding capacity (OBC), melting behavior, viscoelasticity, and hardness. Physical properties were affected by crystallization conditions, by sonication, and by HIU position. The greatest improvement obtained was at 20 °C using low agitation when HIU was placed at the beginning of the SSHE. These conditions result in a sample with 98.9% of OBC, 274 kPa of viscoelasticity and 31 N of hardness. These results show that HIU can be used as an additional processing tool to improve physical properties of a palm-based fat and that the best improvement was obtained as a combination of crystallization conditions and HIU position.     

Invariants,singularities, and parameters of a Kerr solution source

The regularity of a basis of algebraic independent second-order invariants of the Riemann-Christoffel tensor of Kerr space-time is proved by direct calculation in a Boyer-Lindquist coordinate system.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 40–43, December, 1988.     

Modeling of a two-color, two-stage, ultrafast Yb-doped fiber amplifier

We have modeled a two-stage, Yb-doped fiber amplifier system to amplify two-color ultrafast laser pulses in near-infrared. The first and second stages namely preamplifier and power amplifier are single-clad, single-mode and double-clad, single-mode Yb-doped fibers respectively. From numerical simulations of the modeled fiber amplifiers, the optimal lengths of the two fibers to have equal power at two colors centered at 1035 nm and 1105 nm are in agreement with our experimental results. Numerical simulations have also been performed to demonstrate the impact of using a flat-top, two-color seed spectrum on the system performance.     

Establishing a new acoustical laboratory, planning, experiments, experiences

A significant part of the input data for planning the acoustical quality of building is the result of laboratory measurements. Detailed modelling of complex phenomena of sound transmission, like structure borne sound propagation can be solved based on on well planned laboratory experiences. However it seems the constructional details of the testing facilities have important effect on the measured results. The paper describes the process of planning the testing facilities of the Laboratory of Building Acoustics, TU Budapest, which operate as a standardised laboratory, a modelling “tool” for flanking transmission in research and development and which is utilised in teaching too. Some results and conclusions of recent experiments are also reported and discussed here related to the sound reduction index of a heavy brick wall without and with flanking transmission, to the impact sound insulation between the rest of a stair and an adjacent room and also to a possibility to determine the reduction of impact sound transmission of floor coverings.     

Decays of the Higgs Bosons Н, H,A, and H± into a Photon and a Gauge Boson

Russian Physics Journal - Within the framework of the Minimal Supersymmetrtic Standard Model, we have investigated the decay channels of Higgs bosons into a photon and a gauge boson: H(h; A)...     

Synthesis,growth, optical properties of a new metalic crystal

The present fascinating field of research is synthesize, grow, and characterize NLO crystals. Optically good quality single crystals of Potassium Thiourea Carbonate (PTC) crystals have been grown by a slow evaporation method. The grown crystals were characterized by powder X-ray diffraction (XRD), FTIR, UV–vis, micro hardness, impedence analysis. FTIR studies confirm the functional groups present in the grown crystal. The UV–vis spectrum showed the transmitting ability of the crystals in the visible region. Vickers micro hardness is showed the hardness of the material. The impedence of the crystal for various frequencies is also reported.