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Full-Text Articles in Engineering
Structural And Superconducting Properties Of R1 – Xcaxba2cu3o7 – Delta With 0.50 >= X >= 0.00, A. Sedky, A. Gupta, V. P. Awana, A. V. Narlikar
Structural And Superconducting Properties Of R1 – Xcaxba2cu3o7 – Delta With 0.50 >= X >= 0.00, A. Sedky, A. Gupta, V. P. Awana, A. V. Narlikar
Faculty of Engineering - Papers (Archive)
We report here a consolidated study of structural and superconducting properties of Ca substituted R1-xCaxBa2Cu3O7-δ system, with R=Er, Y, Sm, and Nd, and for 0.50>~x>~0.00. Interestingly, with increasing x, Er/Y samples show a behavior significantly different from Sm/Nd. In particular (1) orthorhombic distortion of R:123 lattice is found to be little affected for Er/Y samples with increasing x in comparison to Sm/Nd samples, (2) although Ca substitution leads to oxygen depletion for all the four sets of samples, the average Cu valence is, in general, found to remain invariant with x, (3) ρ(T) is found to show an …
Optimum Design Of Absorber For Mdof Structures, Muhammad N. S Hadi, Y. Arfiadi
Optimum Design Of Absorber For Mdof Structures, Muhammad N. S Hadi, Y. Arfiadi
Faculty of Engineering - Papers (Archive)
This paper discusses the optimum design of tuned mass damper (TMD) for seismically excited building structures. In the design process the multi degree of freedom structures are considered so that it makes improvement to the available design procedures so far, where usually only single mode model is considered.
Nonlinear Single-Electron Tunneling Through Individually Coated Colloid Particles At Room Temperature , S. T. Yau, P. Mulvaney, W. Xu, Geoffrey M. Spinks
Nonlinear Single-Electron Tunneling Through Individually Coated Colloid Particles At Room Temperature , S. T. Yau, P. Mulvaney, W. Xu, Geoffrey M. Spinks
Faculty of Engineering - Papers (Archive)
Single-electron tunneling (SET) has been observed with nanometer coated colloid gold particles at room temperature. We have made the smallest (3-nm) thiol- and silicon dioxide (SiO2)-coated gold particles, from which we obtained SET signals using a scanning tunneling microscope (STM)images reveal individual particles supported by an atomically flat metal surface. The STM tip is used to obtain SET signals from the individual particles, whose shapes have been characterized. The current-voltage curves of the particles exhibit well-defined Coulomb staircases that resemble those obtained at 4.2 K, indicating a strong Coulomb repulsive interaction at room temperature. The clear Coulomb staircases are due …
Elementary Electronic Excitation In Three-Dimensional Electron Gases Under Free-Electron Laser Radiations, W. Xu
Faculty of Engineering - Papers (Archive)
I present a detailed theoretical study of the collective excitation associated with plasmon modes in threedimensional electron gases 3DEG’s, subject to free-electron laser FEL radiations. Using the exact solution of the time-dependent Schro¨dinger equation in which the effect of the electromagnetic e.m. radiation field is included in the Coulomb gauge, I have derived the Green’s function, the density of states DOS, and the density-density correlation function for free electrons in (K,t) and K, representation. With these results, the influence of the FEL radiations on plasmon spectrum in a 3DEG has been studied by employing the randomphase approximation. It has been …
Nonlinear Optical Absorption And Lo-Phonon Emission In Steady-State Terahertz-Driven Three-Dimensional Electron Gases, W. Xu
Faculty of Engineering - Papers (Archive)
We present a detailed theoretical study on nonlinear transport and optical properties in three-dimensional electron gases 3DEG's subjected to intense terahertz THz electromagnetic radiation fields. The steady-state electronic transition rate induced by electron-photon-phonon interactions in a 3DEG system has been derived by using an approach from which the effects of multiphoton processes can be easily included. By solving the momentum- and energy-balance equations based on a steady-state Boltzmann equation, where electron interactions with LO phonons are taken into account, we have investigated the dependence of electron temperature, relaxation time, mobility, multiphoton absorption and emission, and photon-assisted LO-phonon emission on the …
Shear Behaviour Of Railway Ballast Based On Large Scale Triaxial Testing, Buddhima Indraratna, D. Ionescu, H. D. Christie
Shear Behaviour Of Railway Ballast Based On Large Scale Triaxial Testing, Buddhima Indraratna, D. Ionescu, H. D. Christie
Faculty of Engineering - Papers (Archive)
Quarried rock fragments (ballast) constitute one of the most commonly used construction matierals in railway engineering. Ballast is subjected to high stress levels as well as being always exposed to environmental changes. Unsatisfactory performance of railway tracks is often associated with the loss of cross level, track profile and track alignment.
Method To Estimate Water Storage Capacity Of Capillary Barriers, J. C. Stormont, C. E. Morris
Method To Estimate Water Storage Capacity Of Capillary Barriers, J. C. Stormont, C. E. Morris
Faculty of Engineering - Papers (Archive)
This paper presents a method to estimate the additional storage capacity derived from the presence of a capillary break or barrier beneath a soil layer used in a surface cover system. The method involves first estimating the suction head profile in the soil layer at breakthrough. Then, using a relationship between suction head and water content (i.e., the moisture characteristic function), the corresponding water content profile is derived. Integrating the water content over the depth of the soil layer yields the total water in the layer from which the the net storage capacity can be determined. Good agreement was obtained …
Laboratory Determination Of Smear Zone Due To Vertical Drain Installation, Buddhima Indraratna, I. W. Redana
Laboratory Determination Of Smear Zone Due To Vertical Drain Installation, Buddhima Indraratna, I. W. Redana
Faculty of Engineering - Papers (Archive)
This paper is mainly concerned with a laboratory study to investigate the effect of smear due to vertical drain installation. The extent of the smear zone around a vertical drain was studied utilizing a large-scale consolidometer apparatus. The test results reveal that a significant reduction in the horizontal permeability takes place toward a central drain, whereas the vertical permeabilty remains relatively unchanged. The radius of the smear zone was estimated to be a factor of four to five times the radius of the central drain (mandrel), and the measured ratio of horizontal to vertical permeability approached unity at the drain-soil …
Tissue Equivalence Correction For Silicon Microdosimetry Detectors In Boron Neutron Capture Therapy, P. D. Bradley, Anatoly B. Rosenfeld
Tissue Equivalence Correction For Silicon Microdosimetry Detectors In Boron Neutron Capture Therapy, P. D. Bradley, Anatoly B. Rosenfeld
Faculty of Engineering - Papers (Archive)
Reverse-biased silicon p-n junction arrays have been proposed as microdosimetry detectors. The tissue equivalence of such detectors in boron neutron capture therapy (BNCT) is discussed. A comparison of the range-energy relationships of H, He, C, and Li ions in tissue (ICRU-muscle) and silicon is given. A simple geometrical scaling (~0.63) of linear dimensions is required to convert microdosimetric energy deposition measurements performed in silicon to equivalent deposition in tissue. The Monte Carlo technique is used to examine energy deposition for two simple geometrical cases applicable to BNCT.
Thermal Activation And Ac-Field-Induced Discontinuous Domain Jumps In Perovskite La0.7ca0.3mno3, Xiaolin Wang, J. Horvat, Hua-Kun Liu, S. X. Dou
Thermal Activation And Ac-Field-Induced Discontinuous Domain Jumps In Perovskite La0.7ca0.3mno3, Xiaolin Wang, J. Horvat, Hua-Kun Liu, S. X. Dou
Faculty of Engineering - Papers (Archive)
Low-field ac susceptibility was measured on bulk La0.7Ca0.3MnO3 prepared by a partial melting technique. Discontinuous jumps with heights of (1 - 2)105 emu at temperature intervals of 3-5 K were observed in the ac susceptibility. 28 jumps were observed in the temperature range between 4.2 K and the Curie temperature of 250 K, with an ac field amplitude of 1 Oe, a frequency of 117 Hz, and a dc bias field of 5 and 20 Oe. Upon increasing the frequency up to 5000 Hz, the jumps shifted to lower temperature. For a dc bias field of 50 Oe and an …
Magnetic And Superconducting Properties Of Pr In La12xprxbacacu3o7 System With 0.0< X <1.0, V. P. S. Awana, S X. Dou, R. Singh, A. V. Narlikar, S. K. Malik, W. B. Yelon
Magnetic And Superconducting Properties Of Pr In La12xprxbacacu3o7 System With 0.0< X <1.0, V. P. S. Awana, S X. Dou, R. Singh, A. V. Narlikar, S. K. Malik, W. B. Yelon
Faculty of Engineering - Papers (Archive)
We report the results on structural aspects, magnetic, and superconducting properties of the La1-xPrxBaCaCu3O7 system. Both x-ray and neutron diffraction studies reveal that Pr substitutes isostructurally in the tetragonal LaBaCaCu3O7 (La:1113) system until the complete replacement of La by Pr. The superconducting transition temperature, Tc , determined from ac susceptibility measurements decreases, with increasing x. The relative Tc depression due to Pr in the LaBaCaCu3O7 superconductor is less in comparison to that found for La-site Pr substituted LaBa2Cu3O7 (La:123). While …
Structural And Magnetic Properties Of Rsr2fe3o9 (R=La, Y, Pr, And Gd), V. P. S. Awana, S X. Dou, I. Felner, I. Nowik, S. K. Malik, A. Mehta, R. Singh, A. V. Narlikar, W. B. Yelon
Structural And Magnetic Properties Of Rsr2fe3o9 (R=La, Y, Pr, And Gd), V. P. S. Awana, S X. Dou, I. Felner, I. Nowik, S. K. Malik, A. Mehta, R. Singh, A. V. Narlikar, W. B. Yelon
Faculty of Engineering - Papers (Archive)
We have investigated the RSr2Fe3O9 (R=La, Y, Pr, and Gd) materials by several experimental techniques, including x-ray and neutron diffraction, magnetic susceptibility, and Mossbauer spectroscopy measurements. All materials studied are single phase and crystallize in the hexagonal perovskite structure. Magnetic susceptibility studies reveal that, for R=La and Pr, the Fe ions order antiferromagnetically at about TN=190 K. Short range magnetic correlations are observed up to 250 K. For R=La and Pr, 57Fe Mossbauer studies reveal two inequivalent magnetic sextets below 190 K, with the area ratio 2:1. Above TN, one …