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Full-Text Articles in Engineering
Exact Formula For Nondiagonal Green's Functions In Condensed-Matter Physics , T. Toyoda, Y. Takahashi, C. Zhang
Exact Formula For Nondiagonal Green's Functions In Condensed-Matter Physics , T. Toyoda, Y. Takahashi, C. Zhang
Faculty of Engineering - Papers (Archive)
An exact formula for the nondiagonal part of the one-particle temperature Green’s function is obtained within the framework of the nonperturbative canonical formulation of the finite-temperature generalized Ward-Takahashi relation. It is shown that the Landau-level Green’s function for two-dimensional electrons has a nonvanishing nondiagonal part if the electron-electron interaction is included.
Use Of A Narrow-Gap Prewell For The Optical Study Of Charge Buildup And The Fermi-Energy Edge Singularity In A Double-Barrier Resonant-Tunneling Structure , T. A. Fisher, P. D. Buckle, Philip E. Simmonds, R. J. Teissier, M. S. Skolnick, C. R. White, D. M. Whittaker, L. Eaves, B. Usher, P. C. Kemeny, R. Grey, G. Hill, M. A. Pate
Use Of A Narrow-Gap Prewell For The Optical Study Of Charge Buildup And The Fermi-Energy Edge Singularity In A Double-Barrier Resonant-Tunneling Structure , T. A. Fisher, P. D. Buckle, Philip E. Simmonds, R. J. Teissier, M. S. Skolnick, C. R. White, D. M. Whittaker, L. Eaves, B. Usher, P. C. Kemeny, R. Grey, G. Hill, M. A. Pate
Faculty of Engineering - Papers (Archive)
A strained InyGa1-yAs layer is incorporated adjacent to the emitter barrier of an AlxGa1-xAs/GaAs/AlxGa1-xAs double-barrier resonant-tunneling structure (DBRTS), so that it forms a prewell for the electrons that accumulate prior to tunneling into the GaAs quantum well (QW). Observation of photoluminescence (PL) and photoluminescence excitation (PLE) from the prewell then enables a direct optical determination of the charging behavior in the emitter-accumulation region to be achieved. We show in addition that an optical probe of the prewell can, by consideration of the electrostatics, provide a reliable determination of the charge distribution in the whole DBRTS at the peak of the …
Plasmon Assisted Resonant Tunneling In A Double Barrier Heterostructure , C. Zhang, M. L. Lerch, A. D. Martin, Philip E. Simmonds, L. Eaves
Plasmon Assisted Resonant Tunneling In A Double Barrier Heterostructure , C. Zhang, M. L. Lerch, A. D. Martin, Philip E. Simmonds, L. Eaves
Faculty of Engineering - Papers (Archive)
When a double barrier semiconductor structure is biased near a tunneling resonance, charge can accumulate in the quantum well. Coupling between this two dimensional electron gas and the tunneling current is investigated. Experimental data taken inside a region of apparent bistability in one device reveal a satellite on the high energy side of the current resonance in the I(V) characteristic. A theoretical model based on the many-body transfer Hamiltonian formalism shows that a plasmon excitation has remarkably similar structure. Magnetic field data support the plasmon satellite interpretation.
Performance Of Embankment Stabilized With Vertical Drains On Soft Clay, Buddhima Indraratna, A. S. Balasubramaniam, P. Ratnayake
Performance Of Embankment Stabilized With Vertical Drains On Soft Clay, Buddhima Indraratna, A. S. Balasubramaniam, P. Ratnayake
Faculty of Engineering - Papers (Archive)
This study describes the performance of a fldl-scale embankment raised on a soft marine clay, stabilized with vertical band drains in Malaysia. The finite element code CRISP, which is based on critical-state soil mechanics, has been employed to investigate the performance of the embankment and the underlying soft clay. Predictions of the excess pore pressures and both vertical and lateral displacements are made and compared with field observations. The limited use of closed-form solutions for the prediction of settlements at the line of symmetry of the embankment is also discussed. The effectiveness of the prefabricated drains has been evaluated according …
Electron Correlations In A Double-Quantum-Well Structure, C. Zhang
Electron Correlations In A Double-Quantum-Well Structure, C. Zhang
Faculty of Engineering - Papers (Archive)
The electron correlation effect in a double-quantum-well structure is investigated. The local-field correction and static structural factors are calculated for these structures. It is found that the static structural factors show an anomalous behavior at small q due to the coupled quantum-well-plasma excitation and the interlayer structural factor is negative at large q. We also found that the long-wavelength acoustic plasma mode is further softened due to short-range electron correlations. The minimum critical well separation for this mode to exist increases by an amount ∼1/kf1, where kf1 is the Fermi wave vector of the well with higher electron concentration.
Magnetoresistance And V-I Curves Of Ag-Sheathed (Bi,Pb)2sr2ca2cu3o10+Y Tape, E. Babic, I. Kusevic, S X. Dou, Hua-Kun Liu, Q. Y. Hu
Magnetoresistance And V-I Curves Of Ag-Sheathed (Bi,Pb)2sr2ca2cu3o10+Y Tape, E. Babic, I. Kusevic, S X. Dou, Hua-Kun Liu, Q. Y. Hu
Faculty of Engineering - Papers (Archive)
The magnetoresistance and the V-I curves (I>Ic) of a well-characterized Ag-clad (Bi,Pb)2Sr2Ca2Cu3O10+y tape (BPSCCO) with Jc(77 K, B=0)=10 kA/cm2 have been analyzed in the temperature (T) range 80–110 K and magnetic field (B) up to 60 mT. The results obtained after the correction for the parallel conduction through the Ag sheathing and BPSCCO core are similar to those for corresponding single crystals and the epitaxial thin films. The effective activation energy for the flux creep U0 is larger than those for the single crystals and thin films of Bi-Sr-Ca-Cu-O (BSCCO) compound. The variations of the differential resistance Rf (deduced …
Intergranular And Intragranular Critical Currents In Silver-Sheathed Pb-Bi-Sr-Ca-Cu-O Tapes, K. Muller, C. Andrikidis, Hua-Kun Liu, S. X. Dou
Intergranular And Intragranular Critical Currents In Silver-Sheathed Pb-Bi-Sr-Ca-Cu-O Tapes, K. Muller, C. Andrikidis, Hua-Kun Liu, S. X. Dou
Faculty of Engineering - Papers (Archive)
The role of the intergranular and intragranular critical current densities in silver-sheathed Pb-Bi-Sr-Ca-Cu-O tapes is investigated by means of magnetic-moment measurements in perpendicular field at different temperatures using a superconducting quantum interference device magnetometer. We find that low-field magnetic-moment loops are mainly caused by the intergranular (transport) critical current density JcJ but that in high fields the contribution from the intragranular critical current density JcG becomes significant. The low-field data can be described well in terms of a critical-state model for a thin strip of a homogeneous type-II superconductor in a perpendicular field where JcJ flows over the entire tape. …
Case History Analysis Of Mine Water Pollution In New South Wales, Muttucumaru Sivakumar, S Morton, Raghu N. Singh
Case History Analysis Of Mine Water Pollution In New South Wales, Muttucumaru Sivakumar, S Morton, Raghu N. Singh
Faculty of Engineering - Papers (Archive)
In this paper, problems associated with mine waste water discharge quality in two mines are examined in the environmentally sensitive regions in NSW, Australia. In the first mine the problem of controlling and treating surface run-off from a large coal mine site is duscussed. Then study involved sampling and analysis of mine wastewater during various weather conditions over a period of six months. The samples were analysed for a range of physical and chemical water quality parameters. The study indicated that during minor storms, the mine wastewater treatment system worked effectively, but during a moderate to major storm, the treatment …