固溶时效对上引拉铸Cu-0.3Cr-0.1Zr组织性能的影响

用扫描电镜(SEM)、透射电子显微镜(TEM)、涡流电导率测量仪和万能试验机测试分别测量了上引拉铸拉拔之后固溶时效对Cu-0.3Cr-0.1Zr合金抗拉强度及导电率性能的影响,用金相显微镜观察不同拉拔加工率下固溶的显微组织。并探讨了合金的强化机理。结果表明:上引Cu-0.3Cr-0.1Zr合金铸锭经过75%冷拉变形后固溶其组织和力学性能较好。经时效后的固溶态Cu-0.3Cr-0.1Zr合金,抗拉强度和导电率迅速上升,随着时间时间的延长,其抗拉强度达到峰值后呈下降趋势,而导电率则继续上升。Cu-Cr-Zr合金析出强化的重要因素是大量共格弥散的析出相,以共格强化机制估算的强化值423MPa与实验结果 415MPa相近。

S7-200 PLC控制的大锭半连铸引锭装置

本文叙述了应用S7-200 PLC控制原理和方法.根据半连铸生产工艺要求编制了程序,使整个系统能够按照工艺要求进行工作,提高产量和质量使得在成本较低的情况下达到与国外引进设备相同功能的效果。

RF MEMS Switch on Poly-Silicon Substrate

The improvements of the design and the compatibility with silicon IC of RF MEMS switch are presented.The compatibility with silicon IC is realized by dielectric isolation technology,and the decrease of the pull voltage of the switch is done by etching some holes on the metal membrane.The preliminary test results are as follows: C off and C on are 0 32pF,6pF,respectively;the pull down voltage is about 25V.The package of the RF MEMS switch is done by micro stripline,and the isolation and the insertion loss are 35dB,2dB,respectively at 1 5GHz;the switching speed is about 3μs by oscilloscope.

Pullback Attractors for Semi-uniformly Dissipative Dynamical Systems

The existence of pullback attractors for semi-uniformly dissipative dynamical systems under some asymptotic compactness assumptions is considered.A sufficient condition for the existence of pullback attractors is presented.Then,the results are applied to non-autonomous 2D Navier-Stokes equations.

A Remark on the Pullback Attractors for the Non-autonomous Benjamin-Bona-Mahony Equation

In this paper,we show the existence of pullback attractors for the nonautonomous Benjamin-Bona-Mahony equations by establishing the pullback uniform asymptotically compactness.

Gravitational Faraday effect in curved space-time induced by high-power lasers

Gravitational field produced by high-power laser is calculated according to the linearized Einstein field equation in weak field approximation. Gravitational Faraday effect of electromagnetic wave propagating in the above gravitational field is studied and the rotation angle of polarization plane of electromagnetic wave is derived. The result is discussed and estimated under the condition of present experiment facility.

Torsional Vibration Analysis of an FR Driveline System

Towing tractor drivelines are lightly damped non-linear systems. Interactions between components can cause dynamic behavors such as gear gap impact in gear transmissions, shuffle and clonk phenomena in driveline. The torsional vibration of driveline has an important effect on grand engineering vehicle vibration and noise. Through analyzing torsional vibration equations of driveline, torsional vibration model of driveline is developed by using Matlab/Simulink software, Shuffle and clonk phenomena are observed in torsional vibration. The modeling method of analysizing driveline torsional vibration can be used to research and improve similar engineering vehicle driveline behavors.

Interactive Lagrangian density between massive photons and gravitons

The interactive Lagrangian density of massive photons and gravitons is proposed after an investigation into the interaction between photons with or without mass under the influence of gravity either as classical field, gravitational wave, or gravitons from a perspective of quantum field. This interactive Lagrangian density can provide a step-stone for further research of gravitational wave and the possible rest mass of photon.

Generalized Negative Imaginary Lemma for Descriptor Systems

Flexible structure dynamics with collocated force actuators and position sensors lead to negative imaginary （NI） systems. In this paper, the authors study the extension of NI theory to descriptor systems. The authors derive an NI lemma for descriptor systems. This is done by using the transformation from positive real （PR） system to NI system. Then, the Weierstrass Form transformation was involved to transform A and E matrices to be in a special form. An illustrative example is presented to support the result. Negative imaginary systems, positive real systems, descriptor systems, Negative imaginary lemma.

Coupling of 3D Eulerian and Lagrangian Spray Approaches in Industrial Combustion Engine Simulations

The Lagrangian DDM （discrete droplet model） is state-of-the-art for CFD （computational fluid dynamics） simulations of mixture formation and combustion in industrial engines. A commonly known drawback of the DDM approach is the attenuated validity in the dense spray, where the bulk liquid disintegrates into droplets. There the assumption of single droplets surrounded by a homogenous gas field is not reasonable. In this region, the Eulerian-Eulerian multi-phase approach performs better because instead of parcels the spray is represented by the volume fractions of one bulk liquid and several droplet size class phases. A further drawback of the DDM approach is that increasing the spatial resolution of the computational grid leads to a reduced statistical convergence, since the number of spray parcels per computational cell becomes smaller. It is desirable to combine the benefits of both spray approaches in coupled CFD simulations. Therefore, the dense spray region is simulated separately with the Eulerian spray approach on a highly resolved mesh covering only the region close to the nozzle orifice. The entire engine domain with combustion and emission models is simulated with the Eulerian-Lagrangian spray approach for the dilute spray region. The two simulations are coupled through exchange of boundary conditions and model source terms. An on-line coupling interface manages the data transfer between the two simulation clients, i.e., Eulerian spray and engine client. The aim of this work is to extend the coupled spray approach in terms of exchanging combustion related heat and species sources, and consequently creating the link between Eulerian spray and combustion models. The results show mixture formation and combustion in real-case engine simulations, and demonstrate the feasibility of spray model combination in engineering applications.

A Theory of Evolving Natural Constants Based on the Unification of General Theory of Relativity and Dirac’s Large Number Hypothesis

Talcing Dirac's large number hypothesis as true, we have shown [Commun.Theor. Phys. (Beijing, China) 42 (2004) 703] the inconsistency of applying Einstein's theory ofgeneral relativity with fixed gravitation constant G to cosmology, and a modified theory for varyingG is found, which reduces to Einstein's theory outside the gravitating body for phenomena of shortduration in small distances, thereby agrees with all the crucial tests formerly supportingEinstein's theory. The modified theory, when applied to the usual homogeneous cosmological model,gives rise to a variable cosmological tensor term determined by the derivatives of G, in place ofthe cosmological constant term usually introduced ad hoc. Without any free parameter thetheoretical Hubble's relation obtained from the modified theory seems not in contradiction toobservations, as Dr. Wang's preliminary analysis of the recent data indicates [Commun. Theor. Phys.(Beijing, China) 42 (2004) 703]. As a complement to Commun. Theor. Phys. (Beijing, China) 42 (2004)703 we shall study in this paper the modification of electromagnetism due to Dirac's large numberhypothesis in more detail to show that the approximation of geometric optics still leads to nullgeodesies for the path of light, and that the general relation between the luminosity distance andthe proper geometric distance is still valid in our theory as in Einstein's theory, and give theequations for homogeneous cosmological model involving matter plus electromagnetic radiation.Finally we consider the impact of the modification to quantum mechanics and statistical mechanics,and arrive at a systematic theory of evolving natural constants including Planck's h as well asBoltzmann's k_B by finding out their cosmologically combined counterparts with factors ofappropriate powers of G that may remain truly constant to cosmologically long time.

Homogenization of attractors for a class of nonlinear parabolic equations

The relation between the global attractors Aε for a calss of quasilinear parabolic equations and the global attractor A0 for the homogenized equation is discussed, and an explicit error estimate between Aε and A0 is given.

Spin Symmetry in Dirac-Attractive Radial Problem and Tensor Potential

In this paper,we solve the Dirac equation under spin symmetry limit for attractive radial potential including a Coulomb-like tensor interaction.By using the parametric generalization of the Nikiforov-Uvarov method,the energy eigenvalues equation and the corresponding wave functions have been obtained in closed forms.Some numerical results are given too.

Solutions of the Schrdinger Equation with Quantum Mechanical Gravitational Potential Plus Harmonic Oscillator Potential

The solutions of the Schrodinger equation with quantum mechanical gravitational potential plus harmonic oscillator potential have been presented using the parametric Nikiforov-Uvarov method. The bound state energy eigen values and the corresponding un-normalized eigen functions are obtained in terms of Laguerre polynomials. Also a special case of the potential has been considered and its energy eigen values are obtained.

Two-post-Newtonian approximation of the scalar-tensor theory with an intermediate-range force for general matter

Some future space missions measure distances of laser links and angles with unprecedented precision, allowing us to test theories of gravity up to the two-post-Newtonian （2PN） order. Besides, investigation of an intermediate-range force has been of considerable interests in gravitational experiments. Inspired by these ideas, within the framework of the scalar-tensor theory with an intermediate- range force, its 2PN approximation is obtained with Chandrasekhar＇s approach. It includes the 2PN metric and equations of motion for general matter without specific equation of state. The conserved quantities to the 2PN order are isolated with the aid of the energy-momentum complex. We also discuss the prospect of testing and distinguishing the intermediate-range force with the orbital motions of celestial bodies and spaeecrafts.