Failure of Saturated Sand in Non-Symmetrical Cyclic Loading

Extensive experimental studies have been focused on the cyclic behavior of saturated sand under free-field level ground conditions when subjected to earthquake loading. In many practical applications involving earth dams, slopes and buildings, however, soil elements are always subjected to initial static driving shear stresses on the horizontal planes. The impact of initial shear stresses on cyclic behavior and strength of sand is not yet fully understood. The focus of the present study is placed on the initial shear impact on the failure mechanisms of saturated sand varying from loose to dense state. Three distinctly different cyclic failure patterns have been identified. The most critical one is characterized by sudden, run-away deformation without any precautionary signal. The second failure mode is well known as cyclic mobility in which deformation takes place in double amplitude. The third type is the plastic axial strain accumulation in a single direction. It is shown that which failure pattern prevails is complicated, depending on the initial state of sand and the degree of stress reversal

Automated composite ellipsoid modelling for high frequency GTD analysis

The preliminary results of a scheme currently being developed to fit a composite ellipsoid to the fuselage of a helicopter in the vicinity of the antenna location are discussed under the assumption that the antenna is mounted on the fuselage. The parameters of the close-fit composite ellipsoid would then be utilized as inputs into NEWAIR3, a code programmed in FORTRAN 77 for high frequency Geometrical Theory of Diffraction (GTD) Analysis of the radiation of airborne antennas

Coherent spin transport through a 350-micron-thick Silicon wafer

We use all-electrical methods to inject, transport, and detect spin-polarized electrons vertically through a 350-micron-thick undoped single-crystal silicon wafer. Spin precession measurements in a perpendicular magnetic field at different accelerating electric fields reveal high spin coherence with at least 13pi precession angles. The magnetic-field spacing of precession extrema are used to determine the injector-to-detector electron transit time. These transit time values are associated with output magnetocurrent changes (from in-plane spin-valve measurements), which are proportional to final spin polarization. Fitting the results to a simple exponential spin-decay model yields a conduction electron spin lifetime (T1) lower bound in silicon of over 500ns at 60K.Comment: Accepted in PR

Evolution of the band alignment at polar oxide interfaces

First-principles calculations demonstrate the evolution of the band alignment at La0.7A0.3MnO3|La1-xAx|TiO2|SrTiO3(001) heterointerfaces, where A = Ca, Sr, or Ba, as the interfacial A-site composition, La1-Ax, is varied from x = 0.5 to x = 1.0. This variation leads to a linear change of the SrTiO3 valence band offset with respect to the Fermi level of the La0.7A0.3MnO3 metal electrode and hence to a linear change of the Schottky barrier height at this interface. The effect arises due to electrostatic screening of the polar interface which alters the interfacial dipole and hence the electrostatic potential step at this interface. We find that both the La0.7A0.3MnO3 and SrTiO3 layers contribute to screening with both electronic and ionic screening being important for the change in the interface dipole. The results are in agreement with the recent experimental data.Comment: 4 pages, 4 figure

A combined finite element-Langevin dynamics (FEM-LD) approach for analyzing the mechanical response of bio-polymer networks

postprin

Possible surface plasmon polariton excitation under femtosecond laser irradiation of silicon

The mechanisms of ripple formation on silicon surface by femtosecond laser pulses are investigated. We demonstrate the transient evolution of the density of the excited free-carriers. As a result, the experimental conditions required for the excitation of surface plasmon polaritons are revealed. The periods of the resulting structures are then investigated as a function of laser parameters, such as the angle of incidence, laser fluence, and polarization. The obtained dependencies provide a way of better control over the properties of the periodic structures induced by femtosecond laser on the surface of a semiconductor material.Comment: 11 pages, 8 figures, accepted for publication in Journal of Applied Physic

Comparison of chemical profiles and effectiveness between Erxian decoction and mixtures of decoctions of its individual herbs : a novel approach for identification of the standard chemicals

Acknowledgements This study was partially supported by grants from the Seed Funding Programme for Basic Research (Project Number 201211159146 and 201411159213), the University of Hong Kong. We thank Mr Keith Wong and Ms Cindy Lee for their technical assistances.Peer reviewedPublisher PD

Research advances on the anti-aging profile of Fructus lycii: An ancient Chinese herbal medicine

Fructus lycii is a common Chinese herbal medicine used in China for nearly 2000 years. It has beneficial effects on eyes, liver and kidneys; and it has long been considered to be an anti-aging herb in ancient Chinese medicine. Modern studies have partially probed the magic anti-aging property of F. lycii. The beneficial effects of F. lycii on aging are largely attributed to its bioactive components such as polysaccharides, carotenoids and flavonoids. This review focuses on the anti-aging aspect of F. lycii, elaborating the bioactive ingredients accounting for the property, anti-aging pharmacology in terms of its antioxidation capacity, immunomodulative effect and neuroprotective activity. Copyright ©2008 The Berkeley Electronic Press. All rights reserved.published_or_final_versio

Conduction mechanisms of epitaxial EuTiO3 thin films

To investigate leakage current density versus electric field characteristics, epitaxial EuTiO3 thin films were deposited on (001) SrTiO3 substrates by pulsed laser deposition and were post-annealed in a reducing atmosphere. This investigation found that conduction mechanisms are strongly related to temperature and voltage polarity. It was determined that from 50 to 150 K the dominant conduction mechanism was a space-charge-limited current under both negative and positive biases. From 200 to 300 K, the conduction mechanism shows Schottky emission and Fowler-Nordheim tunneling behaviors for the negative and positive biases, respectively. This work demonstrates that Eu3+ is one source of leakage current in EuTiO3 thin films.Comment: 17 pages,4 figures, conferenc

The Helicopter Antenna Radiation Prediction Code (HARP)

The first nine months effort in the development of a user oriented computer code, referred to as the HARP code, for analyzing the radiation from helicopter antennas is described. The HARP code uses modern computer graphics to aid in the description and display of the helicopter geometry. At low frequencies the helicopter is modeled by polygonal plates, and the method of moments is used to compute the desired patterns. At high frequencies the helicopter is modeled by a composite ellipsoid and flat plates, and computations are made using the geometrical theory of diffraction. The HARP code will provide a user friendly interface, employing modern computer graphics, to aid the user to describe the helicopter geometry, select the method of computation, construct the desired high or low frequency model, and display the results