Spatiotemporal saliency detection and salient region determination for H.264 videos

In this study, a spatiotemporal saliency detection and salient region determination approach for H.264 videos is proposed. After Gaussian filtering in Lab color space, the phase spectrum of Fourier transform is used to generate the spatial saliency map of each video frame. On the other hand, the motion vector fields from each H.264 compressed video bitstream are backward accumulated. After normalization and global motion compensation, the phase spectrum of Fourier transform for the moving parts is used to generate the temporal saliency map of each video frame. Then, the spatial and temporal saliency maps of each video frame are combined to obtain its spatiotemporal saliency map using adaptive fusion. Finally, a modified salient region determination scheme is used to determine salient regions (SRs) of each video frame. Based on the experimental results obtained in this study, the performance of the proposed approach is better than those of two comparison approaches.     

Carrier dynamics and intervalley scattering in InN

The carrier cooling and the carrier relaxation of an InN thin film illuminated with two excitation energies of 1.53 and 3.06 eV were studied by an ultrafast time-resolved photoluminescence upconversion apparatus. The hot phonon effect could be accounted for longer effective phonon emission times as compared to the theoretical prediction. The rise time and the LO phonon emission time for 3.06 eV excitation were much smaller than those for 1.53 eV excitation. These differences were attributed to the intervalley scattering between the Γ₁ and Γ₃ valleys in InN when carriers were excited with the energy of 3.06 eV. The intervalley scattering times of 250 fs and 2 ps were estimated for the intervalley scattering from the Γ₁ to Γ₃ valley and the reversed scattering process, respectively.     

Formation mechanism of microcrystalline spherical graphite particles in solidified nickel

Nickel is a well known catalyst that can readily transform carbon into graphite at high temperature. In our designed arc-discharge experiments, diamond easily dissolved in melted nickel and became small graphitic flakes. After the melted nickel had cooled and solidified, there were many microcrystalline-sized spherical graphite particles found on the nickel grain boundaries, surprisingly. It is interesting that only at the hotter area would the spherical graphite be found. This leads to our proposed forming mechanism: the spherical graphite particles were formed during the solidification of nickel. Because the temperature and solubility are high at the hotter area (zone A), the crystallization and growth of graphite became transport-controlled, instead of surface-controlled, and therefore the most common shape of the particles was spherical. This phenomenon, as far as we know, has not been previously observed.     

The Impact of Short-Sale Constraints on Asset Allocation Strategies via the Backward Markov Chain Approximation Method

This paper considers an asset allocation strategy over a finite period under investment uncertainty and short-sale constraints as a continuous-time stochastic control problem. Investment uncertainty is characterised by a stochastic interest rate and inflation risk. If there are no short-sale constraints, the optimal asset allocation strategy can be obtained analytically. We consider several kinds of short-sale constraints and employ the backward Markov chain approximation method to explore the impact of short-sale constraints on asset allocation decisions. Our results show that the short-sale constraints do indeed have a significant impact on these decisions.     

A comparison of different postures for scaffold end-frame disassembly

Overexertion and fall injuries comprise the largest category of nonfatal injuries among scaffold workers. This study was conducted to identify the most favourable scaffold end-frame disassembly techniques and evaluate the associated slip potential by measuring whole-body isometric strength capability and required coefficient of friction (RCOF) to reduce the incidence of injury. Forty-six male construction workers were used to study seven typical postures associated with scaffold end-frame disassembly. An analysis of variance (ANOVA) showed that the isometric forces (334.4-676.3 N) resulting from the seven postures were significantly different (p < 0.05). Three of the disassembly postures resulted in considerable biomechanical stress to workers. The symmetric front-lift method with hand locations at knuckle height would be the most favourable posture; at least 93% of the male construction worker population could handle the end frame with minimum overexertion risk. The static RCOF value resulting from this posture during the disassembly phase was less than 0.2, thus the likelihood of a slip should be low.     

Design of piecewise constant gains for optimal control via Walsh functions

This paper presents a technique for determinating time-varying feedback gains of linear systems with quadratic performance criteria. The gains are approximated by the piecewise constants which axe naturally determined by Walsh functions. After introducing Walsh functions in the beginning we develop an operational matrix for solving state equations. Then using the operational matrix we solve the piecewise constant gains problem.     

Analysis of licking responses in rats: Effects of cholecystokinin and bombesin.

Compared the effects of cholecystokinin (CCK) and bombesin (BBS) on the consummatory response in male albino rats in 3 experiments. The normal licking response pattern did not change as the meal progressed; no predictor was found to indicate when the meal would terminate. Licks normally occurred at about 6/sec, but there were a few licks that occurred at about 3/sec with no licking occurring in the intermediate range; thus, a distinctive bimodal frequency distribution of the interlick interval was formed. CCK reduced the intake of milk and the related licking indices as expected, but it also induced an unusual licking pattern: The contact duration was shortened, the interlick interval was lengthened, and there was an increase in the proportion of licks with long interlick intervals, the effects that accentuated the bimodality of the distribution of interlick intervals. BBS reduced the intake and the related licking indices. The CCK effect may be mediated partially by a change in the motor aspect of the consummatory response; however, BBS reduced intake by simply decreasing the number of licks and shortening the intake duration. BBS may be a candidate for a natural satiety hormone. (37 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Studies of the mesophase development in polymeric fibers during deformation by synchrotron SAXS/WAXD

On-line structural and morphological studies on Kevlar 49 and isotactic polypropylene (iPP) fibers during deformation were carried out using synchrotron small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXD). A novel image analysis method was used to extract quantitative fractions of the crystal phase, the amorphous phase and a mesomorphic (intermediate) phase from two-dimensional (2D) WAXD patterns. Results showed that about 20 wt% in the Kevlar 49 fiber had an intermediate mesophase morphology. The transitions between crystal phase, amorphous phase and mesophase were not obvious during deformation of Kevlar 49 fiber at room temperatures. 2D SAXS patterns indicated that the superstructure of the Kevlar 49 fiber was fibril in nature. 2D WAXD results of iPP fibers showed that the -form crystals were quite defective in the initial state and were converted to the well-known mesomorphic form by drawing at room temperatures. The mesophase in Kevlar 49 fibers was then compared with that in iPP fibers. The shape of one-dimensional equatorial peak of the mesophase in the iPP fiber was similar to that in the Kevlar fiber, indicating that the mesophase in both iPP and Kevlar fibers could be similar in some aspects of molecular arrangement. Corresponding 2D SAXS patterns showed that there was no obvious long period in the mesophase of the drawn iPP fiber. We speculate that the constituents of the mesomorphic fraction extracted in the drawn iPP fibers may consist of partially oriented bundles of helical chains with random helical hands as well as oriented chains with no helical structures (consisting of stereo/tacticity defects). The latter is similar to the mesophase of rigid chains in Kevlar fibers, consisting of only oriented chains with no helical structures.     

Investigation of the Phase Equilibria of Sn-Cu-Au Ternary and Ag-Sn-Cu-Au Quaternary Systems and Interfacial Reactions in Sn-Cu/Au Couples

The phase equilibria of the Sn-Cu-Au ternary, Ag-Sn-Cu-Au quaternary systems and interfacial reactions between Sn-Cu alloys and Au were experimentally investigated at specific temperatures in this study. The experimental results indicated that there existed three ternary intermetallic compounds (IMCs) and a complete solid solubility between AuSn and Cu₆Sn₅ phases in the Sn-Cu-Au ternary system at 200°C. No quaternary IMC was found in the isoplethal section of the Ag-Sn-Cu-Au quaternary system. Three IMCs, AuSn, AuSn₂, and AuSn₄, were found in all couples. The same three IMCs and (Au,Cu)Sn/(Cu,Au)₆Sn₅ phases were found in all Sn-Cu/Au couples. The thickness of these reaction layers increased with increasing temperature and time. The mechanism of IMC growth can be described by using the parabolic law. In addition, when the reaction time was extended and the Cu content of the alloy was increased, the AuSn₄ phase disappeared gradually. The (Au, Cu)Sn and (Cu_,Au)₆Sn₅ layers played roles as diffusion barriers against Sn in Sn-Cu/Au reaction couple systems.     

A finite element study of the effect of the angle between two intersecting cylindrical shells subjected to internal pressure

The results of a study of the critical region of two intersecting cylindrical shells due to internal pressure loading are presented as a function of the angle between the two axes. The investigation was performed using the thin shell element of a three-dimensional finite element program. Three models with the angle between the axes of the two cylindrical shells equal to 30, 60, and 90°, were analyzed. In all of the three models, the diameter ratio of the two shells was 0.5283; the diameter to thickness ratio of the larger or main shell was 44.76, while the same ratio for the smaller or attached shell was 15.487. The results of these analyses show that the stresses in the critical intersection region are least when the two axes are perpendicular to each other; for other angular configurations, the stresses increase as the acute angle between the two axes decrease. This effect of inclination for pressure loading is just opposite of the effect found by authors [1] for external moments. In that case, for in-plane as well as out-ofplane moments, the stresses are larger for normally intersecting shells as compared to other angular configurations.