Hebei University of Technology

Hebei, China

Hebei University of Technology is a public university whose main campus lies in the Guangrong Dao neighborhood of the Hongqiao District in Tianjin, China. It is the first institute of technology in modern Chinese education history. It is among the first group of institutions of higher learning in the national “211-Project” to which priority is given in construction. In order to carry out the “21st Century Education Revitalizing Action Plan”. Wikipedia.

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We have systematically investigated the influence of oxygen vacancy defects on the structural, electronic and magnetic properties of La1-xSrxMnO3 (x = 1/3) film by means of ab initio calculations using bare GGA as well as GGA+U formalism, in the latter of which, the on-site Coulombic repulsion parameter U for Mn 3d orbital has been determined by the linear response theory. It is revealed that the introduction of the vacancy defects causes prominent structural changes including the distortion of MnO6 octahedra and local structural deformation surrounding the oxygen vacancy. The GGA+U formalism yields a significantly larger structural change than the bare GGA method, surprisingly in contrast with the general notion that the inclusion of Hubbard U parameter exerts little influence on structural properties. The distortion of MnO6 octahedra leads to a corresponding variation in the hybridization between Mn 3d and O 2p, which gets strengthened if the Mn-O distance becomes smaller and vice versa. The magnetic moments of the Mn atoms located in three typical sites of the vacancy-containing supercell are all larger than those in the pristine system. We have characterized the O-vacancy defect as a hole-type defect that forms a negative charge center, attracting electrons.

Liu H.-T.,Hebei University of Technology
Engineering Fracture Mechanics | Year: 2017

In the present paper, the non-local theory, the generalized Almansi's theorem and the Schmidt method are developed for the analysis of a permeable mode-I crack in a piezoelectric medium(PZT-4, P-7, PZT-5H) under the harmonic stress waves. The problem is formulated through Fourier transformation into two pairs of dual integral equations, in which the unknown variables are the displacement jumps across the crack surfaces. For solving the dual integral equations, the displacement jumps across the crack surfaces are directly expanded as a series of Jacobi polynomials. The dynamic non-local stress and the dynamic non-local electric displacement are obtained at the crack tips. Numerical examples are provided to show the effects of the crack length, the characteristics of the harmonic wave and the lattice parameter on the dynamic stress field and the dynamic electric displacement field near the crack tips in a piezoelectric medium. Different from the classical solutions, the present solution exhibits no stress and electric displacement singularities at the crack tips in a piezoelectric medium. © 2017 Elsevier Ltd

Zhang Z.H.,Hebei University of Technology
Optics and Lasers in Engineering | Year: 2012

Full-field fringe projection techniques have been widely studied in academia and applied in industrial fields because of the advantages of non-contact operation, fast full-field acquisition, high accuracy and automatic data processing. Phase data map is calculated from one or multiple captured fringe pattern images on the measured object surface, which are called as single-shot and multiple-shot 3D measurement methods. Although multiple-shot methods can give highly accurate data for measuring static objects, it could be degraded by disturbance, such as vibration and environmental noises between gap of image shot. However, single-shot methods are insensitive to vibrational noises because of capturing only one image. Therefore, various single-shot methods have been actively researched recently with the advent of new imaging and projecting devices. This paper reviews the single-shot 3D shape measurement techniques by projecting and capturing one fringe pattern image on the object surface, the wrapped phase demodulation algorithms from one captured image. The challenging problems and future research directions are discussed to advance single-shot 3D shape measurement techniques. © 2012 Elsevier Ltd. All rights reserved.

Min C.-H.,Hebei University of Technology
Journal of Power Sources | Year: 2010

A three-dimensional, two-phase and non-isothermal model of a proton exchange membrane fuel cell (PEMFC) based on the previously developed model is established using the two-fluid method. This two-phase model considers the liquid water transport in both cathode and anode sides and accounts for the intrinsic heat transfer between the reactant fluids and the solid matrices. The latent heat of water condensation/evaporation is considered in the present model. The numerical results demonstrate that the lower cathode humidity is beneficial for cell performance. In the anode side, the water vapor can be condensed at high current density because the water vapor transport is less than the hydrogen consumption rate. Near the catalyst layer, the reactant fluid temperature is higher than the solid matrix temperature, and far from the catalyst layer, the temperature difference between the reactant fluid and the solid matrix decreases. Near the channel, the reactant fluid temperature is lower than the solid matrix temperature. © 2009 Elsevier B.V. All rights reserved.

A method of cleaning multilayer copper wirings in ultra large scale integrated circuits after chemical-mechanical polishing, the method including: a) preparing a cleaning solution, the cleaning solution including between 0.1 and 5 wt. % of a nonionic surfactant, between 0.1 and 7 wt. % of a corrosion inhibitor, and between 0.1 and 0.6 wt. % of a chelating agent in deionized water; b) adjusting the pH value of the cleaning solution to between 7 and 8 using triethanolamine; c) during the production of ULSI, after the chemical-mechanical polishing step, washing the multilayer copper wirings with the cleaning solution at a flow rate of between 500 and 5000 mL/min for between 0.5 and 1 min; d) ultrasonic washing in the presence of deionized water under following conditions: 60 Hz frequency of ultrasound, 50 C. temperature, and between 0.5 and 1 min ultrasonic time; and e) drying the multilayer copper wirings.

A method of cleaning tungsten plug surfaces in ultra large scale integrated circuits after chemical-mechanical polishing, the method including: a) preparing a cleaning solution by mixing deionized water, between 15 and 30 g/L of an active agent with respect to the deionized water, between 5 and 20 g/L of a chelating agent with respect to the deionized water, and between 1 and 60 g/L of a corrosion inhibitor with respect to the deionized water; b) after alkaline chemical-mechanical polishing, washing the tungsten plug surfaces using the cleaning solution at a flow rate of between 1000 and 4000 g/min for between 30 s and 3 min.

A method of cleaning copper material surfaces in ultra large scale integrated circuits after polishing, the method including: a) mixing and stirring between 1 and 4 wt. % of a surfactant, between 0.5 and 3 wt. % of a chelating agent, between 0.1 and 5 wt. % of a corrosion inhibitor, and deionized water, to yield a water soluble cleaning solution with pH value of between 7.4 and 8.2; and b) washing the copper material surfaces using the cleaning solution after alkaline chemical-mechanical polishing under following conditions: between 2000 and 3000 Pa of pressure; between 1000 and 5000 mL/min of flow rate:; and at least between 0.5 and 2 min of washing time.

CITIC Dicastal CO. and Hebei University of Technology | Date: 2016-03-15

The present invention provides an aluminium alloy refiner. The aluminium alloy refiner is characterized by comprising 7 to 10 parts of Ti, 2 to 3 parts of B and the balance of Al by weight, for example, 8 parts of Ti, 3 parts of B and 89 parts of Al by weight. The aluminium alloy refiner is prepared by rapid solidification. After the refiner is added to A356.2 aluminium alloy, the grain size of the alloy is significantly reduced than that of the aluminium alloy treated by a conventional refiner. Moreover, the solubility of metals in liquid may be increased due to rapid solidification, such that the refiner is more easily absorbed by the aluminium alloy melt after being added to the aluminium alloy.

CITIC Dicastal CO. and Hebei University of Technology | Date: 2016-03-16

The invention provides a method of refining aluminum alloy, which is characterized in that aluminum-based nanometer quasicrystal alloy is used as an aluminum alloy refiner to refine the aluminum alloy; the aluminum-based nanometer quasicrystal alloy does not comprise Si, Fe or Cr; the aluminum-based nanometer quasicrystal alloy consists of (1) Al; (2) Mn and (3) La and/or Ce. The refiner selected in the invention is rare earth-containing alloy which has a strong refinement ability on the aluminum alloy, and is nanometer quasicrystal; after adding the rare earth-containing alloy to melt, the element distribution of the rare earth-containing alloy is more uniform than that of traditional alloy; and nanometer quasicrystal particles substantially increase the number of heterogeneous nucleation particles and improve the grain refinement effect of the aluminum alloy.

Mi Y.-J.,Hebei University of Technology
International Journal of Theoretical Physics | Year: 2012

We study the dynamics of classical correlation and quantum discord of two-qubit system interacted with the thermal reservoir. Special attention is paid to the difference between the entanglement and quantum discord when considering the influences of the nonzero mean photon number and quantum fluctuation of the vacuum. It is shown that in the same range of the physical parameters, the factors leading to the entanglement sudden death only accelerates the decay of quantum discord, and the quantum discord can last for an infinite period when the entanglement disappears. So the quantum discord is more robust than entanglement under this decoherence environment, and quantum discord is a more general measure of quantum correlation than entanglement. © 2011 Springer Science+Business Media, LLC.

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