Spatiotemporal segmentation for compact video representation

In this paper, a novel hierarchical object-oriented video segmentation and representation algorithm is proposed. The local variance contrast and the frame difference contrast are jointly exploited for structural spatiotemporal video segmentation because these two visual features can indicate the spatial homogeneity of the grey levels and the temporal coherence of the motion fields efficiently, where the two-dimensional (2D) spatiotemporal entropic technique is further selected for generating the 2D thresholding vectors adaptively according to the variations of the video components. After the region growing and edge simplification procedures, the accurate boundaries among the different video components are further exploited by an intra-block edge extraction procedure. Moreover, the relationships of the video components among frames are exploited by a temporal tracking procedure. This proposed object-oriented spatiotemporal video segmentation algorithm may be useful for MPEG-4 system generating the video object plane (VOP) automatically.     

Sonosynthesis of microstructures array for semiconductor photovoltaics

The properties of the silicon samples subjected to cavitation impacts have been studied. It was shown that high-intensity (15 W/cm²) and high-frequency (1–6 MHz) sonication of silicon samples in the liquid nitrogen induces changes of the physical, chemical, and structural properties of semiconductor surface. Optical, atomic force and scanning electron microscopy techniques as well as energy dispersive X-ray spectroscopy, X-ray diffraction and photoresponse spectroscopy were used. The experimental study demonstrates the microstructure formation as well as a change of the chemical composition at the silicon surface. It was found that a significant rise in value and expansion of the spectral range of photosensitivity take place after cavitation treatment. The photoresponse of about 2.0 eV can be connected with the formation of Si-rich SiN_x compound inside the ultrasonically structured region of Si. The obtained value of the refractive index confirms this assumption.     

Design of AlxGa1−xAs/GaAs/InyGa1−yAs triple junction solar cells with anti-reflective coating

Multi-junction solar cells (SC) made from III–V compound semiconductors are still in the development phase. Here, we perform calculations for multi-junction cells: Al_xGa_1−xAs top junction, GaAs middle junction and In_yGa_1−yAs bottom junction (all of these materials with band-gaps between 2.1 and 0.8 eV) in order to obtain the optimal band gap and thickness for each junction under the AM1.5 solar radiation spectrum. The ideal photo-current density is around 15.5 mA/cm². In order to reduce the natural reflectivity, an anti-reflective coating (ARC) was chosen, based on a MgF₂/ZnS double layer, allowing for a significant increase of the current density with respect to a cell without it. Calculations of external quantum efficiency (QE) were also performed for the three cases mentioned above: ideal one, taking into account the total reflection and with the ARC double layer. Finally, when more realistic calculations are done, taking into account the carrier recombination at each sub-cell, and the light reflection for a tandem cell with the designed ARC on top, the expected conversion efficiency (η), under the AM 1.5 spectrum (without concentration), was determined to be around 38.5%, making this an attractive III–V compound tandem cell to be investigated in the near future.     

Micromechanical modeling to determine the compressive strength and failure mode interaction of multidirectional laminates

Computational models to predict the compressive strength of carbon fiber reinforced polymer matrix composites are proposed here, motivated by the failure mechanisms observed in compression tests. Delamination, fiber kink-banding and their interaction are seen to dominate the failure response. An upscaled semi-homogenized laminate model is developed to predict the observed compressive response of multidirectional laminates. A generalized 2-D formulation is presented to determine the interfaces most susceptible to delamination. Subsequently, cohesive elements are added along these interfaces to introduce delamination capability in the model. Predictions of the model are compared against experimental data, and are found to be in agreement with respect to compressive strength and failure modes. Further, the effect of stacking sequence on the compressive strength and failure mode is investigated.     

Antiviral and Anticancer Activity of Cisplatin Derivatives of Tilorone

Cisplatin derivatives containing tilorone and a tilorone derivative were synthesized and characterized employing IR analysis, mass spectrometry, elemental analysis, and chain length. The polymeric cisplatin derivatives prevent growth of four transformed cell lines, L929, 143, Vero, and BS-C-1 and effectively inhibit four viruses including the DNA viruses; herpes simplex-1, vaccinia, and Varicella zoster, and the RNA virus, reovirus in the micrograms/mL range. The tilorone polymers display activity against both transformed cells and DNA and RNA viruses at biologically important concentrations.     

Synthesis,Structural Characterization,and Initial Evaluation as Anticancer Drugs of Dibutyltin Polyamines Derived from Various 4,6-Diaminopyrimidines

A number of diaminopyrimidines have been incorporated into dibutyltin polyamines with molecular weights ranging from 3.5 × 10⁴ to 3.7 × 10⁶ and product yields from 47 to 88%. Infrared spectroscopy is consistent with the inclusion of the diaminopyridines into the polymer backbone with the IR spectroscopy showing the formation of the Sn–N bond as well as the presence of bands from both reactants being present in the polymer. F MALDI MS is also consistent with the products being polymeric and containing units from both the dibutyltin and pyrimidine reactants. The products exhibit good inhibition of cancer cell lines including those derived from human lung, bone, breast, prostrate, and colon cancers. Inhibition occurs within the same concentration range, and lower than that of the most widely employed chemotherapeutic drug, cisplatin.     

An advanced start algorithm for all-integer programming

In this paper, we present an all-integer cutting plane technique called the Advanced Start Algorithm (ASA), for solving the all-integer (otherwise linear) programming problem (IP). We develop a good advanced primal-infeasible start based on the optimal solution to the LP relaxation, and use a two-stage dual/primal algorithm to obtain the optimal solution to (IP). We illustrate the operation of the ASA on three small problems, and exhibit computational results on a set of standard test problems.     

Enhanced functional brain imaging by using adaptive filtering and a depth compensation algorithm in diffuse optical tomography

Reflectance diffuse optical tomography (rDOT) of brain function is limited by its high sensitivity to the superficial tissues (i.e., the scalp and skull) and by its severe decrease in measurement sensitivity with increased depth. Significant interference in rDOT results from spontaneous fluctuations that are embedded in both the superficial tissues and brain, such as arterial pulsation and vasomotion. In this study, first we investigate coherence and phase shift of the spontaneous fluctuations in the resting state, within the superficial tissues and at various depths of the brain, respectively. We demonstrate that the spontaneous fluctuations originating from arterial pulsations ( ～ 1 Hz) are spatially global and temporally coherent, while the fluctuations originating from vasomotion ( ～ 0.1 Hz) tend to have less coherence with increased depth. Second, adaptive cancellation of spontaneous fluctuations with a frequency-specific strategy is utilized and validated in both resting and activation (evoked by a finger-tapping task) states. Third, improved depth localization of motor activation in reconstructed rDOT images is achieved by combining adaptive cancellation with a depth compensation algorithm that we recently reported.     

On assessing spatial uniformity of particle distributions in quality control of manufacturing processes

There are many situations in quality control of manufacturing processes in which the quality of a process is characterized by the spatial distribution of certain particles in the product, and the more uniform the particle distribution is, the better the quality is. To realize quality control and guide process improvement efforts, the degree of spatial uniformity of particle distributions needs to be assessed. On the other hand, many quantitative metrics have been developed in areas outside manufacturing for measuring uniformity of point patterns, which can be applied for this purpose. However, critical issues exist in applying existing metrics for quality control relating to which metrics to choose and how to use them in specific situations. To provide general guidelines on these issues, this research identifies popular uniformity metrics scattered in different areas and compares their performance in detecting nonuniform particle distributions under various practical scenarios through a comprehensive numerical study. Effects of different factors on the performance of the metrics are revealed and the best metric is found. The use and effectiveness of the selected metric is also demonstrated in a case study where it is applied to data from emerging material fabrication processes in nanomanufacturing and biomanufacturing.     

Theory and numerics of geometrically non-linear gradient plasticity

This work presents the theory and the numerics of a thermodynamically consistent formulation of geometrically non-linear gradient plasticity. Due to the lack of the classical local continuum formulation to produce physically meaningful and numerically converging results within localization computations, a thermodynamically motivated gradient plasticity formulation is envisioned. Especially within the framework of crystal plasticity we resort to physically motivated arguments in terms of geometrically necessary dislocations densities that imply the incorporation of higher gradients. In a first simplified approach presented here we adopt the gradient of the internal hardening variable as a provision for geometrically necessary dislocations. We start from a thermodynamic formulation within a geometrically non-linear setting including the additional contribution of the gradient of the internal history variable. This introduces e.g. the vectorial hardening flux and the quasi-nonlocal drag stress. At the numerical side, besides the balance of linear momentum, the algorithmic consistency condition has to be solved in weak form. Thereby, the crucial issue is the determination of the active constraints exhibiting plastic loading which is solved by an active set search algorithm borrowed from convex non-linear programming. Finally, some demonstrative numerical examples complement the presentation.