Structural, magnetic and electrical properties of (La0.70−xNdx)Sr0.30Mn0.70Cr0.30O3 with 0 ≤ x ≤ 0.30

The structural, magnetic and electrical properties of (La_0.70−xNd_x)Sr_0.30Mn_0.70Cr_0.30O₃ perovskites (0 ≤ x ≤ 0.30) prepared by the usual ceramic procedure were investigated. Structural Rietveld refinement revealed that these compounds crystallize in a rhombohedral perovskite structure when x = 0, 0.10 and 0.20, while for x = 0.30 the structure becomes orthorhombic (Pbnm). It was found that the substitution of La by Nd reduces the Curie temperature (T_C). The FC, ZFC, M(H) and AC susceptibility measurements show typical canted-antiferromagnetism for the Nd-doped samples, in which a ferromagnetic component coexists with predominant antiferromagnetic interactions. The values of the magnetization (M(H)) decrease very slightly when increasing the Nd content, compared to the undoped sample (M_S values at 5 T and 2 K are, respectively, 47.9, 47.3 and 47.5 emu/g for x = 0.10, 0.20 and 0.30, compared to 48.2 emu/g for x = 0), indicating that the Nd³⁺ contribution is negligible compared to the total moment of the ferromagnetic (Mn/Cr) network. The resistivity increases by several orders of magnitude with Nd-doping and the semi-conducting behaviour persists in the whole temperature range. The interaction between Mn⁴⁺–O–Cr³⁺and Cr³⁺–O–Cr³⁺ is responsible for the semi-conducting state.     

Performance of olive waste ash concrete exposed to elevated temperatures

This study explores the influence of olive waste ash (OWA) on the performance of concrete exposed to elevated temperatures in the range from 400 to 600 °C. The performance of concrete to elevated temperature was evaluated using compressive strength and electrical charge of concrete. Three OWA levels were used in the study: 7%, 15%, and 22% by weight of cement. The other experimental parameters investigated in the study were elevated temperature (400 and 600 °C), aggregate type (crushed basalt and volcanic tuff), w/c ratio (0.5 and 0.7), and air content (non-air and air entrained). After the initial moist curing period of 90 days, concrete specimens were exposed to elevated temperatures for a period of 2 h using an electric furnace.     

Copy-move forgery detection of duplicated objects using accurate PCET moments and morphological operators

This paper presents a new method for copy-move forgery detection of duplicated objects. A bounding rectangle is drawn around the detected object to form a sub-image. Morphological operator is used to remove the unnecessary small objects. Highly accurate polar complex exponential transform moments are used as features for the detected objects. Euclidian distance and correlation coefficient between the feature vectors are calculated and used for searching the similar objects. A set of 20 forged images with duplicated objects is carefully selected from previously published works. Additional 80 non-forged images are edited by the authors and forged by duplicating different kinds of objects. Numerical simulation is performed where the results show that the proposed method successfully detect different kinds of duplicated objects. The proposed method is much faster than the previously existing methods. Also, it exhibits high robustness to various attacks such as additive white Gaussian noise, JPEG compression, rotation, and scaling.     

Calculating optimal modulation periods to maximize the peak capacity in two-dimensional HPLC

Theoretical calculations are presented to optimize modulation period for maximum total peak capacity in comprehensive two-dimensional HPLC (2D-HPLC) taking into account the effect of modulation on the apparent peak capacity of the first-dimension (1D) separation. Results indicate that modulation periods are most favorable when they are adjusted to approximately 2.2-4 times the standard deviation of a 1D peak in order to avoid excessively short run times at the second dimension (2D). Data are presented that effective peak capacities of several thousand in 60 min can be expected for practical 2D-HPLC conditions, utilizing 1D gradient elution followed by 2D isocratic elution, that remain at approximately 50-70% of the theoretical maximum peak capacity. This work suggests that lower modulation frequencies and longer 2D separation times than previously proposed are favorable under realistic chromatographic conditions, alleviating some practical problems associated with 2D-HPLC.     

A dynamic variational multiscale method for viscoelasticity using linear tetrahedral elements

In this article, we develop a dynamic version of the variational multiscale (D‐VMS) stabilization for nearly/fully incompressible solid dynamics simulations of viscoelastic materials. The constitutive models considered here are based on Prony series expansions, which are rather common in the practice of finite element simulations, especially in industrial/commercial applications. Our method is based on a mixed formulation, in which the momentum equation is complemented by a pressure equation in rate form. The unknown pressure, displacement, and velocity are approximated with piecewise linear, continuous finite element functions. To prevent spurious oscillations, the pressure equation is augmented with a stabilization operator specifically designed for viscoelastic problems, in that it depends on the viscoelastic dissipation. We demonstrate the robustness, stability, and accuracy properties of the proposed method with extensive numerical tests in the case of linear and finite deformations.     

Electron beam irradiated HDPE/EVA/Mg(OH)2 composites for flame-retardant electric cables

The mechanical properties and flammability of high-density polyethylene (HDPE)/ethylene vinyl acetate (EVA) mixed with various amounts of magnesium hydroxide (Mg(OH)₂) as the filler in composites, irradiated with electron beam at an irradiation dose of 150 kGy, have been studied. It is found that high-energy electron beam irradiation has significant effects on the mechanical properties of the HDPE/EVA/Mg(OH)₂ composites. The tensile strength and elastic modulus increased greater than in the unirradiated ones. Meanwhile, with increasing the content of Mg(OH)₂ in the composites, the limiting oxygen index (LOI) value increased sharply. The microstructure of the caves of the unirradiated HDPE/EVA/Mg(OH)₂ composites show poor interface of composites compared with the irradiated ones, as observed in SEM micrographs.     

Enhanced structural and optical properties of ZnO nanopowder with tailored visible luminescence as a function of sodium hydroxide to zinc sulfate mass ratio

ZnO nanopowders of tailored particle sizes were synthesized using a simple wet chemical method, by controlling the mass ratio of the precursors. The physical properties were investigated as a function of OH^?/Zn²⁺ mass ratio (x). The structural properties of the synthesized nanoparticles (NPs) are studied using X-ray diffraction (XRD). XRD patterns show pure wurtzite structure. Microstructural parameters dependence on x ratio was studied based on Williamson-Hall model. We notice an increase in crystallite size (17–24?nm) and a decrease in strain values when the x ratio increases (0.5–1.4). The best crystallinity corresponds to the higher mass ratio. Indeed, for x?=?1.4 we obtain the largest crystallite size, the lowest strain and stacking faults. The TEM images support the XRD results. Raman spectra confirm the purity of the synthesized ZnO powder. Furthermore, the optical properties were examined by UV–vis and Photoluminescence as a function of precursor’s ratio. Absorption data show a band gap red-shift of the ZnO-NPs with increase in particle’s size. Moreover, we found that the ZnO-NPs luminescence in the visible range can be engineered by changes of x ratio. This constitutes an advantage for the use of ZnO-NPs in different wavelength areas in optoelectronic applications covering UV-Blue-Green domain for the LED design, sensors…     

Patterns of Innovation Capabilities in KIBS Firms: Evidence from the 2003 Statistics Canada Innovation Survey on Services

The aim of this paper is to shed light on complementarities and substitutions between various types of innovation capabilities in knowledge-intensive-based service (KIBS) firms. The data used in this study are the responses of 2,625 innovative firms to the 2003 Statistics Canada Innovation Survey on services. The empirical results suggest the presence of three patterns of complementary innovation capabilities, one pattern of substitute activities and finally, four patterns of innovation capabilities that are independent from each other. Hence, the results suggest the presence of complementarities: first, between internal R&D, external R&D, acquisition of equipment and machinery, and marketing activities; second, between external R&D, acquisition of equipment and machinery, acquisition of external knowledge and marketing activities; third, between acquisition of equipment and machinery, acquisition of external knowledge and marketing activities. Such complementarities lead to the conclusion that, in practice, managers of KIBS firms consider the consolidation of these capabilities jointly instead of separately. The paper also discusses issues related to patterns of capabilities that are substitutes and independent from each other. The results of this study also show significant heterogeneity in the determinants of the different patterns of innovation capabilities.