Framework for the integrated video quality assessment

Through years of development Content Networks (CN) have become more sophisticated and more technically diverse. Modern CN are designed to be more adaptive to communication environment, devices and user requirements. However, one open issue is the still fluctuating quality of service provision. As a result user experience can be negatively affected. In order to maintain a satisfactory level of user experience it is crucial to develop a feasible solution to measure the extent to which video services meet users?? expectation. Assessing video quality with respect to users?? subjective opinions is a complex task. In this paper we address challenges of this task and design an integrated framework using a number of comprehensive functional modules. Our framework integrates objective quality assessment models of Artifacts Measurement (AM) and Quality of Delivery (QoD) approaches. Only the fittest models are activated by the framework considering requirements of individual evaluation tasks. We also introduce our recent work of realising key functional modules of the framework. Joint subjective experiments between two institutes have also been carried out for the purpose of model implementation and evaluation. Results from experiments verify the concept of an integrated framework and show the effectiveness of its key modules in estimating the quality level of video services.     

核厚对铝泡沫夹芯板抗弯性能的影响

研究了在4点弯曲工况下，铝泡沫核心/热塑性复合材料面层构成的夹芯板的核心厚度对变形机制的影响。通过全过程应力分析和观察，得出不同核厚下一系列的失效机制。各个样本厚度对应不同失效区域均可观察到高应变集中。相对薄的样本表面出现折皱和破裂现象，一些核也会碎裂，相对厚的样本的失效取决于核的凹陷。增加表面厚度可以避免核的凹陷，否则，可以观察到关键的核被剪碎。     

Assessing the accuracy of using aggregated traffic traces in network engineering

Aggregated traffic traces are commonly used in network engineering for QoS or performance parameters evaluation. Many performance models come from such aggregated traces. However, real traffic is a marked point process combining two processes: one for the arrival times of packets and the other for their size in bytes. This paper deals with assessing whether aggregated traces are a good representation of real traffic. Based on the analysis of many traffic traces, and focusing only on loss probability, it is shown that the packet drop probability obtained for the aggregated traffic traces can significantly differ from the real packet drop probability obtained for the real traffic traces. Then, a solution which enables one to obtain correct loss probability based on aggregated traffic traces is proposed by determining the correct aggregation scale and traffic parameters to be applied.     

The Influence of Polyhedral Oligomeric Silsequioxanes on Domain Microstructure in Polyurethane Elastomers

The influence of polyhedral oligomeric silsequioxanes (POSS) as covalently bound hybrid physical property modifiers on the segmental dynamics and morphology of segmented polyurethane elastomers has been studied by solid-state magic sandwich echo nuclear magnetic resonance (MSE-NMR), differential scanning calorimetry (DSC) and atomic force microscopy (AFM). A model system has been synthesized which incorporates diol functionalized POSS over a range of loadings into the hard-block of a methylene di-isocyanate - butane diol - poly(tetramethylene glycol) (MDI-BDO-PTMG) segmented PU elastomer. MSE-NMR has been employed to probe the segmental dynamics of the PU system as a function of POSS loading and it has been demonstrated that low levels of POSS as a substitute chain extender, both rigidify the hard-block phase of the PU and significantly alter both the phase morphology, mixing and structure of the inter-phase domains. These observations are supported by more classical AFM and DSC morphological characterization of the POSS-PU hybrid systems which show significant re-structuring of the phase domain structure of the PU and ordering of the crystalline hard-block domains. This work demonstrates the application of a multi-scaled experimental approach towards understanding the effects of three-dimensional, nano-scale cage moieties on the already complex phase structure of segmented polyurethanes. Through these efforts, new insight has been gained into the mechanisms by which low levels of a nano-material such as a cubic sesquioxane, can impact the phase separation and segmental dynamics of block ter-polymer polyurethanes.     

The microstructure of electrodeposited titanium-aluminum alloys

The microstructure of electrodeposited titanium-aluminide alloys containing 3.6 to 24.1 at. pct Ti was studied by transmission electron microscopy. The surface morphology of the deposits showed that they contained nodular and faceted grains which tended to be less faceted at higher Ti contents. Extensive 111 twinning was observed in all deposits, and growth striations parallel to were observed in the low Ti deposits. The growth of nodules was linked to the presence of these twins; it was hypothesized that the twin boundaries act as easy atomic attachment points and, therefore, enhance the growth rate. The presence of twins and striations was used to pro-pose a growth mechanism. The 5.3, 15.8, and 24.1 at. pct Ti deposits were single-phase grains of the Ll₂ crystal structure, as opposed to the expected equilibrium two-phase mixture of face-centered cubic (fcc) Al (saturated with Ti) and D0₂₂ Al₃Ti. Calculated electron diffraction in-tensity data were used to demonstrate that the decrease in intensity of the superlattice reflections in the substoichiometric deposits is due to a reduction in the difference in atomic scattering factors between the two lattice site types. formerly NIST/NRC Postdoctoral Research Associate, National Institute of Standards and Technology.     

About the Realistic Porosity of Porous Glasses

Nitrogen adsorption, mercury intrusion, scanning electron microscopy and small-angle X-ray scattering have been used to determine the texture properties of a selected mesoporous glass. The glass has been prepared by a combined acid and alkaline leaching treatment of a phase separated sodium-borosilicate initial glass. Residues of silica gel, remaining in the pores of the investigated glass after the treatment with alkaline solution, lead to differences in the results of the standard characterization techniques nitrogen adsorption and mercury intrusion.In order to explain these differences, small-angle scattering experiments in combination with scanning electron microscopy have been performed.Here, a well-defined range order L 60 nm has been selected and a 50% porosity results. The behaviour of the second derivative of the small-angle scattering correlation function has been checked by the use of the linear simulation model.     

The effects of tantalum on the microstructure of two polycrystalline nickel-base superalloys: B-1900 + Hf and MAR-M247

Changes in the γ/γ'/carbide microstructure as a function of Ta content were studied in conventionally cast B-1900 + Hf and both conventionally cast and directionally solidified MAR-M247.* The effects of tantalum on the microstructure were found to be similar in both nickel-base superalloys. In particular, the γ' and carbide volume fractions increased approximately linearly with tantalum additions in both alloys. The γ' phase compositions did not change as tantalum additions were made with the exception of an increase in the tantalum level. Bulk tantalum additions increased the tantalum, chromium, and cobalt levels of the γ phase in both alloy series. The increase in the concentrations of the latter two elements was attributed to a decrease in the γ phase fraction with increasing bulk tantalum level and nearly constant γ' /γ partitioning ratios. It was demonstrated that the large increase in the γ ' volume fraction was a result of tantalum not affecting the partitioning ratios of the other alloying elements. The addition of tantalum led to a partial replacement of the hafnium in the MC carbides, although the degree of replacement was reduced by the solutionizing and aging heat treat-ment. In addition, chromium-rich M₂₃C₆ carbides formed as a result of MC carbide decomposition during heat treatment.     

Effects of moisture and UV exposure on liquid molded carbon fabric reinforced nylon 6 composite laminates

Liquid molding of thermoplastics has been limited by high resin viscosity, high temperature processing requirements, and a short processing window [Sibal PW, Camargo RE, Macosko CW. Designing nylon 6 polymerization for RIM. In: Proceedings of the second international conference on reactive processing of polymers, Pittsburgh, PA; 1982, p. 97–125.]. The processing parameters for vacuum assisted resin transfer molding (VARTM) developed by the authors and previously reported [Pillay S, Vaidya UK, Janowski GM. Liquid molding of carbon fabric-reinforced nylon matrix composite laminates. J Thermoplast Compos Mater 2005;18:509–27] have been adapted to process carbon/nylon 6 composite panels. The present work addresses the effects of moisture and ultraviolet (UV) exposure on the static and dynamic mechanical properties of carbon fabric reinforced, thermoplastic polyamide 6 matrix panels processed using VARTM. The Bao and Yee dual diffusivity model [Bao LR, Yee AF. Moisture diffusion and hygrothermal aging in bismaleimide matrix carbon fiber composites: Part II – Woven and hybrid composites. Compos Sci Technol 2002;62:2111–9] was applied to evaluate the moisture uptake for the C/PA6, fully immersed in distilled water at 100 °C. SEM results show that moisture exposure result in surface micro-cracks compromise of the fiber–matrix interface. The flexural strength is lowered by 45%, after exposure to moisture at 100 °C. UV exposure up to 600 h causes yellowing of the samples and an increase in crystallinity from 40% to 44%.     

The Rule of Thirds: Controlling Junction Chirality and Polarity in 3D DNA Tiles

The successful self-assembly of tensegrity triangle DNA crystals heralded the ability to programmably construct macroscopic crystalline nanomaterials from rationally-designed, nanoscale components. This 3D DNA tile owes its “tensegrity” nature to its three rotationally stacked double helices locked together by the tensile winding of a center strand segmented into 7 base pair (bp) inter-junction regions, corresponding to two-thirds of a helical turn of DNA. All reported tensegrity triangles to date have employed $\left(Z+2/3\right)$ turn inter-junction segments, yielding right-handed, antiparallel, “J1” junctions. Here a minimal DNA triangle motif consisting of 3-bp inter-junction segments, or one-third of a helical turn is reported. It is found that the minimal motif exhibits a reversed morphology with a left-handed tertiary structure mediated by a locally-parallel Holliday junction—the “L1” junction. This parallel junction yields a predicted helical groove matching pattern that breaks the pseudosymmetry between tile faces, and the junction morphology further suggests a folding mechanism. A Rule of Thirds by which supramolecular chirality can be programmed through inter-junction DNA segment length is identified. These results underscore the role that global topological forces play in determining local DNA architecture and ultimately point to an under-explored class of self-assembling, chiral nanomaterials for topological processes in biological systems.