不可思议——奇妙的数

6174这个数表面看起来并没有什么特别，似乎和其它的四位数一样平常，实际上6174是个身怀绝技、深藏不露的数，它的本领需要在特定的场合才能显露出来。下面我们就来制造一下这种场合。

Magnetic force distribution and deformation law of sheet using uniform pressure electromagnetic actuator

The distribution of magnetic forces and current on sheet and coil was analyzed in detail according to the structural parameter of the coil which was invalid.The result shows that the current direction based on simulation result agrees with the principles of uniform pressure electromagnetic actuator.The reason for coil failure was proposed.Then the magnetic forces on the sheet were input into an explicit finite element software ANSYS/LS-DYNA to analyze the deformation law of the sheet.

Effects of static magnetic fields on melt flow in detached solidification

A series of three-dimensional numerical computations were conducted to understand the effects of different static magnetic fields on thermal fluctuation and melt flow during the detached solidification of CdZnTe. Numerical calculations were carried out by three different configurations of magnetic field: without magnetic field, with an axial magnetic field (AMF) and with a cusp-shaped magnetic field (CMF). The results reveal that the magnetic fields can effectively suppress the melt flow and thermal fluctuation and the suppression effect of the AMF is stronger than that of the CMF. Besides, the physical mechanism of thermocapillary?buoyancy convection instability was discussed and the effects of magnetic field on the critical Marangoni number were also obtained.

Effect of electromagnetic force and anode gas on electrolyte flow in aluminum electrolysis cell

Based on the commercial computational fluid dynamics software CFX-4.3, electrolyte flow fields in a 156 kA pre-baked anode aluminum electrolysis cell were investigated in three different cases where the electrolyte melt was driven by different kinds of force, i.e. electromagnetic force only, the anode gas drag force only and both of the former two forces. The results show that when electromagnetic force was introduced only, most of the electrolyte moves horizontally; when anode gas drag force was introduced only, the electrolyte flows mainly around each anode with small circulation; when electromagnetic force and anode gas drag force were both introduced together, the structure of the electrolyte flow fields and the velocity of electrolyte are similar to that of the case where only anode gas drag force is used. The electrolyte flow fields are mainly determined by the anode gas drag force.

Hysteresis model of magnetostrictive actuators and its numerical realization

This paper presents two numerical realization of Preisach model by Density Function Method (DFM) and F Function Method (FFM) for a giant magnetostrictive actuator (GMA). Experiment and simulation showed that FFM is better than DFM for predicting precision of hysteresis loops. Lagrange bilinear interpolation algorithm is used in Preisach numerical realization to enhance prediction performance. A set of hysteresis loops and higher order reversal curves are predicted and experimentally verified. The good agreement between the measured and predicted curves shows that the classical Preisach model is effective for modelling the quasi-static hysteresis of the GMA.

Mode II fracture analysis of double edge cracked circular disk subjected to different diametral compression

A detailed analysis of mode II stress intensity factors(SIFs) for the double edge cracked Brazilian disk subjected to different diametral compression is presented using a weight function method. The mode II SIFs at crack tips can be obtained by simply calculating an integral of the product of mode II weight function and the shear stress on the prospective crack faces of uncracked disk loaded by a diametral compression. A semi-analytical formula for the calculation of normalized mode II SIF, f _Ⅱ, is derived for different crack lengths (from 0.1 to 0.7) and inclination angles (from 10° to 75°) with respect to loading direction. Comparison between the obtained results and finite element method solutions shows that the weight function method is of high precision. Combined with the authors previous work on mode I fracture analysis, the new specimen geometry can be used to study fracture through any combination of mode I and mode II loading by a simple alignment of the crack relative to the diameter of compression loading, and to obtain pure mode II crack extension. Another advantage of this specimen geometry is that it is available directly from rock core and is also easy to fabricate.

Study of Changes in the Thermodynamic Functions in a Magnetic Field

The authors offered the new formula of the thermodynamic functions in a magnetic field. The authors have also found that thermodynamic functions of internal energy dUand free energy dF changes in the magnetic field.

A Possible Interpretation of Burst-Like Characteristics of Explosive Events

Explosive events have been observed to occur consecutively in bursts at intermittent locations along theboundary near the opposite polarity. The aim of the present paper is to explore a possible mechanism to interpret thisburst-like characteristic of explosive events. The 2D magnetohydrodynamic (MHD) numerical simulations with resistivityhave been carried out to reproduce the intermittent spatial-temporal magnetic reconnection events taking place along thelong, compressible current sheet. The observed density enhancements in previously published results have been verifiedto be associated to magnetic reconnection sites. Late observational evidences, which support present attempts, have alsobeen found, at least in morphological evolution of the consecutive explosive events.

Thermodynamics of Third Order Lovelock-Born-Infeld Black Holes

We here explore black holes in the third order Lovelock gravity coupling with nonlinear Born-Infeld electro- magnetic field. Considering special second and third order coefficients （＆g = 363 = a2）, we analyze the thermodynamics of third order Lovelock-Born-Infeld black holes and, in 7-dimensional AdS space-time, discuss the stability of black holes in different event horizon structures. We find that the cosmological constant A plays an important role in the distribution of black hole stable regions.

Pressure and Doping Effects on Critical Temperature in MgB_2 and Nonmagnetic Borocarbides within Two-Band Eliashberg Theory

Critical temperature of Mg1-xAlxB2, MgB2-xCx are calculated using two-band Eliashberg theory in intermediate e-ph coupling. Analytical calculations are conducted for different values of doping parameters x in this compounds. Pressure effects on critical temperature in MgB2 and nonmagnetic borocarbide YNi2B2C are also investigated. Results is compared with available experimental data and good agreement is achieved.

Unification of Gravity and Electromagnetism

Gravity and electromagnetism are two sides of the same coin, which is the clue of this unification. Gravity and electromagnetism are represented by two mathematical structures, symmetric and antisymmetric respectively. Einstein gravitational field equation is the symmetric mathematical structure. Electrodynamics Lagrangian is three parts, for electromagnetic field, Dirac field and interaction term. The definition of canonical energy momentum tensor was used for each term in Electrodynamics Lagrangian to construct the antisymmetric mathematical structure; symmetric and antisymmetric gravitational field equations are two sides of the same Lagrangian.

Two Independent Numerical Studies Demonstrating How to Efficiently Eliminate Electrolysis Side Reactions in Magneto-Hydro-Dynamic Pumping System

In this work, a numerical study for designing a new kind of MHD （Magneto-Hydrn-Dynamic） pumps is presented. This technique makes a compromise between electrolysis prevention and high flow rate performance. This technique should eliminate electrolytic bubble generation, electrodes wear and fluid propriety modification. All these side phenomena are prevented by considering isolated electrodes. The numerical presented results in this paper demonstrate that continuous MHD pumping is possible with isolated electrodes. The MHD excitation combines a high frequency altering current with a low frequency altering magnetic field. In order to validate our results, two independent theoretical methods for computing flow rate are followed. The two presented independent approaches show that high flow rate is possible even with isolated electrodes. To overcome the problem of dimensioning this kind of pumps, a generic numerical analysis is proposed. Hence, the pump performances as functions of the external parameter are studied and tools to calculate for a given fluid and the optimal high frequency regime are provided.

The Application of the Combined Method for Selection of Optimal Excitation Parameters

The quality as well as reliability of electrical energy transmitted to consumers is one of the main parameters of successful operation of the power system. The searching of optimal coefficient＇s combination of PSS （power system stabilizer） is the main goal of this article. The possibility of application of the new combined approach for the optimal excitation＇s settings search is presented. MC （Monte Carlo） method, in order to search and select the optimal combination of excitation system, was applied. The proposed method has been researched with a mathematical model of the power system. This model has been built using Matlab/Simulink software. Paper shows advantages and disadvantages of the proposed methods.

Comparison between Two Vertical Enclosures Filled With Porous Media under the Effect of Radiation and Magnetohydrodynamics

A numerical study has been carried out to investigate the temperature distribution and the natural convection heat transfer in axisymmetric two-dimensional vertical saturated porous cylinder with steady state laminar flow. A comparison between two situations is done under the effect of MHD （magnetohydrodynamics） and radiation. In the two situations, the vertical walls of the cylinder are cooled with constant wall temperature and a constant heat generation subjected along the centerline of the cylinder. The first case for cylinder with insulated upper surface and cooled bottom surface while the second case for cylinder with cooled upper surface and insulated bottom surface. The governing equations used are continuity, momentum and energy equations which are transformed to dimensionless equations. The finite difference approach is used to obtain all the computational results using the MATLAB-7 programming. The parameters affected the system are Rayleigh number ranging within （102≤ Ra ≤104）, radiation parameter （0≤ Rd ≤ 2） and magnetohydrodynamics MHD （Mn） （0 ≤ Mn≤ 2）.The results show that the temperature of Case 1 is more than that in Case 2 at constant Ra, Mn and Rd while the value of the stream in Case 2 is greater than that in Case 1. Nu increase with the increase of Rd and increasing Mn caused the temperature to increase and the streamline dropped while Nu decreased. A correlation has been set up to give the average Nusselt number variation with Ra, Rd and Mn for which the results are found to be in good agreement with previously published researches.

AN ANALYSIS OF AXISYMMETRIC MAGNETIC FIELD OF LINEAR OSCILLATION MOTOR

In this paper, using axial field finite analysis method, the field of a movable core type linear oscillation motor is analyzed. The program of axial field finite analysis is worked out. Using this program, we analyze various fields, including the field excited by permanent magnet materials, the field by two coils respectively, and the fields with the core moving to various positions.

Polishing of Titanium Alloy Blade Root with Elastic Magnetic Toolic Tool

Removal of milling marks at the root fillet of titanium alloy blade is a tough work because of the interference between the polishing tool and the workpiece.A polishing method based on elastic magnetic tool was proposed.The software ANSYS Maxwell was used to simulate the effect of different pole orientation arrangements on the magnetic field distribution.A comparison of polishing effect was made between elastic and inelastic magnetic pole carriers.The processing parameters of the elastic magnetic tool polishing for the blade root were optimized by orthogonal experiment(Taguchi)method.Results show that compared with the inelastic magnetic polishing tool,the elastic magnetic polishing tool with polyurethane as the pole carrier can effectively improve the surface quality of the polished workpiece.Under the optimal processing parameters(rotational speed=900 r/min,feeding rate=6 mm/min,machining gap=1.5 mm and abrasive size=10‒14μm),the original milling marks at the blade root are effectively removed and the average surface roughness Ra is dropped from 0.95μm to 0.12μm,which verifies the feasibility of the elastic magnetic polishing tool in the surface finishing of the titanium alloy blade root.

Efficient splitting schemes for magneto-hydrodynamic equations

We present in this paper several efficient numerical schemes for the magneto-hydrodynamic(MHD)equations. These semi-discretized(in time) schemes are based on the standard and rotational pressure-correction schemes for the Navier-Stokes equations and do not involve a projection step for the magnetic field. We show that these schemes are unconditionally energy stable, present an effective algorithm for their fully discrete versions and carry out demonstrative numerical experiments.

Containment of high-speed rotating disk fragments

Disk burst accidents sometimes happen in aeroengines.To avoid tragic consequences,aeroengine casings must have sufficient containment capability.Experiments and simulations need to be conducted to study the impact,distortion,and perforation caused by disk burst and which may give important clues to potential failure mechanisms.This paper presents some containment tests of high-speed rotating disk fragments,in which the original disks were burst into three equal fragments within a predetermined rotating speed range.The failure modes of the containment casing varied significantly with the thickness of the containment casing.Shearing,tearing,tensile fracture,and large plastic stretching deformation occurred in a thin-walled containment casing,while a thick-walled casing could contain disk fragments and withstand large plastic deformation.Numerical simulations were carried out to study the impact process and failure modes further.Good agreement was found between the results of the simulations and the tests.

Effect of Transverse Correlation Function on the Thermodynamic Quantities of Ferromagnetic Systems

The effect of transverse correlation between spins on the thermodynamic properties of ferromagnetic systems is investigated in details. Qualitatively, at finite temperature the transverse correlation reflects the short-range interaction between spins, so that lowers the internal energy and consequently raises the free energy. It also means the introduction o[ some ordering, and hence lowers the entropy. It is depressed by the field which forces the spins to turn to the field direction, so that it decreases with the field when temperature is fixed. The low-temperature expansion of the energy shows that the inclusion of the transverse correlation at least partly considers the interaction between spin waves.

Nonlinear identification of electro-magnetic force model

Conventional attractive magnetic force models (proportional to the coil current squared and inversely proportional to the gap squared) cannot simulate the nonlinear responses of magnetic bearings in the presence of electromagnetic losses,flux leakage or saturation of iron.In this paper,based on results from an experimental set-up designed to study magnetic force,a novel parametric model is presented in the form of a nonlinear polynomial with unknown coefficients.The parameters of the proposed model are identified using the weighted residual method.Validations of the model identified were performed by comparing the results in time and frequency domains.The results show a good correlation between experiments and numerical simulations.