Influence of textile treatment on mechanical and sorption properties of flax/epoxy composites

The aim of the present work is to study the effect of conventional textile treatments of woven flax on the mechanical properties and the water sorption of flax/epoxy composites. The flax fabrics are standard 2/2 twills. Various treatments are carried out on fabric such as mercerization, bleaching, and leaching for long fibers or on yarn such as leaching for short fibers. A model, based on a modified rule of mixture applied to composite reinforced with woven fabric, is developed to include the effect of fiber and porosity volume fractions on composite stiffness and strength. Most treatments improve tensile stiffness and strength of flax/epoxy composite and reduce composite water sorption. We prove by X‐ray fluorescence analysis, thermogravimetric analysis, and tensile tests of dry fabric that it is due to an improvement in the interfacial bonding between fibers and matrix. The best performances are achieved with bleaching and mercerization treatment. The weakest performances are obtained with the composites made with leached yarns. POLYM. COMPOS., 34:1761–1773, 2013. © 2013 Society of Plastics Engineers     

Improved harmonic suppression efficiency of single-phase APFs in distorted distribution systems

In this study, a control method is proposed to improve the harmonic suppression efficiency of the single-phase active power filter in a distorted power system to suppress current harmonics and reactive power. The proposed method uses the self-tuning filter (STF) algorithm to process single-phase grid voltage in order to provide a uniform reference grid current, which increases the efficiency of the system. The results of the simulation study are presented to verify the effectiveness of the proposed control technique in this study.     

Monotonic torsional resistance and fatigue resistance of novel SCOPE RS instruments

To evaluate monotonic torsional resistance and fatigue resistance of novel SCOPE RS instruments and to compare ROTATE, Hyflex CM, OneCurve, and ProTaper Next instruments as a counterpart. The instrument groups were as follows: SCOPE RS; ROTATE; HyflexCM; OneCurve; ProTaperNext. The cyclic fatigue resistance of unused instruments was tested at both room and body temperatures (n = 10). The time to fracture, the mean number of cycles until failure, and the length of the fractured fragments were analyzed. The monotonic torsional resistance of new instruments was measured in accordingly American National Standards/American Dental Association No. 28 and International Organization for Standardization 3630–1:2008 specifications (n = 10). The maximum torque and angular deflection at break were recorded. The fractographic examination was performed by scanning electron microscope. Energy‐dispersive X‐ray spectroscopy was used to investigate the microstructure of NiTi instruments. One‐way ANOVA with Games‐Howell Post Hoc multiple comparisons tests were used (p < .05). The ROTATE had superior cyclic fatigue resistance than other groups in both temperature conditions (p < .01). However, it exhibited lower torsional resistance than SCOPE RS (p < .01). SCOPE RS had superior torsional resistance than other groups (p < .01). Micrographs revealed typical features of fatigue behaviors in all groups. Weight percentages of the Ni and Ti revealed similarity for all instruments. The novel SCOPE RS instruments presented superior monotonic torsional resistance but failed to show any improvement in the cyclic fatigue resistance compared with its counterparts, ROTATE, HyflexCM, and OneCurve.     

A comparison of the space requirements of multi-dimensional quadtree-based file structures

A comparison is made of the space requirements of pointer and a number of pointer-less implementations of multidimensional quadtree-based file structures. The database is assumed to be static. In order to make the comparison realistic, considerations such as computer byte sizes are taken into account, and fields are constrained to start on bit and byte boundaries where appropriate. In many practical cases, the pointer quadtree requires less space than the pointer-less quadtree. This effect is more pronounced for octrees and data of higher dimension. Empirical data from a cartographic batabase are used to support the analysis.The support of the National Science Foundation under Grant IRI8802457 is gratefully acknowledged     

Nonexistence of global solutions for a class of nonlocal in time and space nonlinear evolution equations

In this paper, we study the nonlocal nonlinear evolution equation

${}^C{D}_{0|t}^{\alpha }u(t,x)?(J1\left|u\right|?\left|u\right|)(t,x){+}^C{D}_{0|t}^{\beta }u(t,x)={\left|u(t,x)\right|}^p,t>0,x\in {\mathbb{R}}^d,$

where $1<\alpha <2$, $0<\beta <1$, $p>1$, $J:{\mathbb{R}}^d\to {\mathbb{R}}_{+}$, $1$ is the convolution product in ${\mathbb{R}}^d$, and ${}^C{D}_{0|t}^q$, $q\in \{\alpha ,\beta \}$, is the Caputo left-sided fractional derivative of order $q$ with respect to the time $t$. We prove that the problem admits no global weak solution other than the trivial one with suitable initial data when $1<p<1+\frac{2\beta }{d\beta +2(1?\beta )}$. Next, we deal with the system

where $1<\alpha <2$, $0<\beta <1$, $p>1$, and $q>1$. We prove that the system admitsnon global weak solution other than the trivial one with suitable initial data when $1<pq<1+\frac{2\beta }{d\beta +2(1?\beta )}max\{p+1,q+1\}$. Our approach is based on the test function method.     

ConcaveCubes: Supporting Cluster‐based Geographical Visualization in Large Data Scale

In this paper we study the problem of supporting effective and scalable visualization for the rapidly increasing volumes of urban data. From an extensive literature study, we find that the existing solutions suffer from at least one of the drawbacks below: (i) loss of interesting structures/outliers due to sampling; (ii) supporting heatmaps only, which provides limited information; and (iii) no notion of real‐world geography semantics (e.g., country, state, city) is captured in the visualization result as well as the underlying index. Therefore, we propose ConcaveCubes, a cluster‐based data cube to support interactive visualization of large‐scale multidimensional urban data. Specifically, we devise an appropriate visualization abstraction and visualization design based on clusters. We propose a novel concave hull construction method to support boundary based cluster map visualization, where real‐world geographical semantics are preserved without any information loss. Instead of calculating the clusters on demand, ConcaveCubes (re)utilizes existing calculation and visualization results to efficiently support different kinds of user interactions. We conduct extensive experiments using real‐world datasets and show the efficiency and effectiveness of ConcaveCubes by comparing with the state‐of‐the‐art cube‐based solutions.     

Fast mode decision algorithm for H.264/SVC enhancement layer

Scalable video coding (SVC) has been standardized to extend the capabilities of the H.264 advanced video coding (AVC). The SVC can compress several video sequences of various resolutions as a single bit-stream. In the SVC enhancement layer, for Joint Scalable Video Model (JSVM) software implementation, an exhaustive mode decision process based on the base layer mode predictions is performed to obtain the best mode for each macroblock (MB). This technique may achieve a higher coding efficiency; however, it induces a significant computational complexity in the encoding engine. In order to speedup the SVC encoder, a fast mode decision algorithm was proposed in this paper. In other words, our aim was to decrease the number of candidate modes to reduce the computational complexity and maintain the same level of coding efficiency, this approach used the spatial and temporal correlation between MB situated at the enhancement layer and its co-located MB at the base layer. Our statistical analyses were made using several HD sequences with different motion characteristics. Experimental results show a significant improvement in terms of time encoding which is a major constraint for any real-time implementation. However, this gain is accompanied with an acceptable loss in video quality and a tolerable bit rate increase for most media supports. In fact, our proposed algorithm permits a major improvement that can reach up to 64.9 % in terms of computational effort. This gain will induce an average loss yield to 10.5 or 13.87 % that is comparable to the 13.12 % of the He Li’s algorithm with an acceptable loss in terms of subjective video quality.     

Least‐squares‐based adaptive target localization by mobile distance measurement sensors

A least‐squares‐based adaptive algorithm with forgetting factor is proposed for localization of a target by a mobile distance measurement sensor. This problem, in its most general form, was tackled in a recent paper using a gradient adaptive algorithm, assuming distance measurements are directly available. We establish that the proposed algorithm bears the same stability and convergence properties as the gradient algorithm previously studied. It is demonstrated via simulations that the proposed algorithm converges significantly faster to the location estimates than the gradient algorithm for high forgetting factor values and significantly reduces the noise effects for small values of the forgetting factor. Furthermore, a more challenging form of the original problem is considered, where distance information is required to be deduced from time of flight measurements, considering a time of flight‐based active distance measurement sensor and an environment with unknown signal permittivity/speed; the proposed algorithm is redesigned to solve this problem. Copyright © 2014 John Wiley & Sons, Ltd.