共查询到20条相似文献,搜索用时 93 毫秒
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共振法和相位法可以测量声速,本文使用逐差法处理实验数据以减小实验中的随机误差和仪器误差。实验中测量的物理量较多,人工处理数据比较繁琐,且容易出错。因此,本文使用Matlab软件和逐差法处理数据。把测量的实验数据和仪器不确定度输入Excel表格中,然后把Excel文件引入到Matlab软件中,运行逐差法计算的程序后可以直接得到声速,以及测量的百分差和相对不确定度,处理过程快捷精确。经过计算发现:相位法测量声速的百分差略低于共振法测量声速的百分差。 相似文献
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1"伏安法"测电阻 伏安法测电阻是普通物理电磁学的一个经典实验,传统的实验方法有两种--电流表内接法和外接法.由于电流表的内阻RA和电压表的内阻Rv的存在,给实验带来系统误差. 相似文献
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利用“求差法”测电阻 总被引:1,自引:1,他引:0
1"伏安法"测电阻
伏安法测电阻是普通物理电磁学的一个经典实验,传统的实验方法有两种--电流表内接法(图1)和电流表外接法(图2).由于电流表的内阻RA和电压表的内阻Rv的存在,给实验带来系统误差. 相似文献
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交流等效参数的测定是高校普通物理实验中的很重要的内容.目前多采用交流电桥法,Q表法和三表法.本文介绍的示波法较上述方法具有形象直观,简便易行的优点. 相似文献
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An accumulation layer is formed on the emitter side of a biased resonant tunneling diode (RTD) leading to a similar subband structure as in the ordinary MOS-system. Electrons occupying the subbands can tunnel through the RTD-structure and give rise to a significant contribution to the diode current. We calculate the subband current from our semiclassical transport model developed earlier for the ordinary tunneling current. The model includes quantum interference and bulk scattering by utilizing an optical approximation for the coherent part of the wave function. The subband current turns out to be of the same order of magnitude as the ordinary tunneling current component. It is shifted to higher voltages and therefore it increases the valley current. In order to reduce the subband current and improve the peak-to-valley current ratio (PVCR), we propose a novel RTD-structure with a grading in front of the emitter barrier. The purpose of the grading is to suppress the formation of the accumulation layer and thereby decrease the valley current. Calculations show that PVCR increases by a factor of two using a proper design of the grading. 相似文献
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We report on an all-electrical measurement of the spin Hall effect in epitaxial Fe/InxGa(1-x)As heterostructures with n-type (Si) channel doping and highly doped Schottky tunnel barriers. A transverse spin current generated by an ordinary charge current flowing in the InxGa(1-x)As is detected by measuring the spin accumulation at the edges of the channel. The spin accumulation is identified through the observation of a Hanle effect in the voltage measured by pairs of ferromagnetic Hall contacts. We investigate the bias and temperature dependence of the resulting Hanle signal and determine the skew and side-jump contributions to the total spin Hall conductivity. 相似文献
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Morphogen, a class of signaling molecules to direct and control pattern formation of cell and tissue, is first synthesized in a local region and then conveyed to other regions or degraded. In the previous studies, this transport process was modeled by deterministic models of ordinary differential equations. In microcosmic environments, however, the process is often affected by stochastic fluctuations (or the noise). It remains unclear how this noise affects morphogen gradients. Here, we build a spatiotemporal master equation model for the process of morphogen transport in a finite developmental field, from which we derive the first-order moment equations of this master equation. We derive the analytical expression of the local accumulation time that the morphogens reach a steady state, and find that this time is nonlinear with respect to the cell positions. We also derive the approximate expressions of the steady-state variances, the Fano factors and the local accumulation time of the variance. Interestingly, we find that the local accumulation time for the variance of the morphogen number is shorter than that of its corresponding second-order moment. Moreover, the noise in the morphogen number is almost not affected by the distance from the cellular position to morphogen source. In addition, we further study some quantities (e.g., potential energy and diffusion force) from the view of physical-chemical mechanisms, and uncover that the diffusion force is a key factor for the formation of the morphogen gradient. Our results provide insights on morphogen diffusion. 相似文献
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We consider a Gaussian Beam (GB) resonant system for high frequency gravitational waves (HFGWs) detection. At present, we find the optimal signal strength in theory through setting the magnetic component of GB in a standard gaussian form. Under the synchro-resonance condition, we study the signal strength (i.e., transverse perturbative photon fluxes) from the relic HFGWs (predicted by ordinary inflationary model) and the braneworld HFGWs (from braneworld scenarios). Both of them would generate potentially detectable transverse perturbative photon fluxes (PPFs). Furthermore we find optimal system parameters and the relationship between frequency and effective width of energy fluxes accumulation. 相似文献
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AES and PES studies of nitrogen in iron implanted with molecular nitrogen ions having an energy of 120 keV and doses on the order of 1017 N-atoms/cm2 were performed. Measuring nitrogen concentration depth profiles, a remarkable accumulation of nitrogen near surface was found besides the ordinary concentration maximum at the depth of mean projected range Rp of nitrogen ions. In addition to strong nitride bonding state a weakly bonded nitrogen was also observed. It manifested itself by time-dependent changes in spectra and by a distinct value of N 1s binding energy. The reasons for the concept of weakly bonded nitrogen, probably of molecular form, are discussed. 相似文献
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Algebraic dynamics solutions and algebraic dynamics algorithm for nonlinear ordinary differential equations 总被引:2,自引:2,他引:0
The problem of preserving fidelity in numerical computation of nonlinear ordinary differential equations is studied in terms
of preserving local differential structure and approximating global integration structure of the dynamical system. The ordinary
differential equations are lifted to the corresponding partial differential equations in the framework of algebraic dynamics,
and a new algorithm—algebraic dynamics algorithm is proposed based on the exact analytical solutions of the ordinary differential
equations by the algebraic dynamics method. In the new algorithm, the time evolution of the ordinary differential system is
described locally by the time translation operator and globally by the time evolution operator. The exact analytical piece-like
solution of the ordinary differential equations is expressed in terms of Taylor series with a local convergent radius, and
its finite order truncation leads to the new numerical algorithm with a controllable precision better than Runge Kutta Algorithm
and Symplectic Geometric Algorithm. 相似文献
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The Hamilton--Jacobi method for solving ordinary differential equations is presented
in this paper. A system of ordinary differential equations of first order or second
order can be expressed as a Hamilton system under certain conditions. Then the
Hamilton--Jacobi method is used in the integration of the Hamilton system and the
solution of the original ordinary differential equations can be found. Finally, an
example is given to illustrate the application of the result. 相似文献
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P. Munayco J. Munayco M. Valenzuela P. Rochette J. Gattacceca R. B. Scorzelli 《Hyperfine Interactions》2014,224(1-3):257-262
Some terrestrial areas have climatic and geomorphologic features that favor the preservation, and therefore, accumulation of meteorites. The Atacama Desert in Chile is among the most important of such areas, known as dense collection areas. This desert is the driest on Earth, one of the most arid, uninhabitable locals with semi-arid, arid and hyper-arid conditions. The meteorites studied here were collected from within the dense collection area of San Juan at the Central Depression and Coastal Range of Atacama Desert. 57Fe Mössbauer spectroscopy was used for quantitative analysis of the degree of weathering of the meteorites, through the determination of the proportions of the various Fe-bearing phases and in particular the amount of oxidized iron in the terrestrial alteration products. The abundance of ferric ions in weathered chondrites can be related to specific precursor compositions and to the level of terrestrial weathering. The aim of the study was the identification, quantification and differentiation of the weathering products in the ordinary chondrites found in the San Juan area of Atacama Desert. 相似文献
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We derive the q-Taylor's formula with its q-remainder through the q-differentiation approach. Comparison between q-Taylor's expansion with the ordinary Taylor's formula is made, which shows that the q-remainder is different from the ordinary one. 相似文献
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