Application of ultrasonic method in asphalt concrete testing for fatigue life estimation

This paper presents the possibilities of applying ultrasonic methods in asphalt concrete specimen testing in order to estimate fatigue life using ultrasonic characteristics of specimens. The procedures and results of testing cylinder shaped samples of both ultrasonic analysis and fatigue life testing are described. The ultrasonic method was first used in order to obtain the seismic characteristics of specimens. Then, the specimens were tested for fatigue lives using the repeated-loading indirect tensile test equipment (SDU-Asphalt Tester). To be able to model the fatigue lives, in addition to conventional fatigue model parameters new parameters from this ultrasonic analysis were taken into consideration. These additional parameters are acquired from the seismic measurements. Hence, only by examining the ultrasonic method, it will be possible to predict the fatigue lives of the specimens non-destructively.     

Fastness and dyeability improvement of wool fabric pretreated with oxalate derivatives

Wool fabrics were pretreated with calcium and sodium oxalate in acidic and alkaline pH media. The pretreated and untreated fabric samples were then dyed in the same bath with acid dyes by the exhaustion technique. The pretreated fiber sample surfaces were observed using a scanning electron microscope. The color strength and fastness properties of the fabrics were investigated. The results of the study showed that pretreatment with oxalate derivatives can be used as a means of improving the dyeability of wool fibers. As the dyed, pretreated wool fabrics had higher color strength and fastness results than the untreated wool fabrics, the mechanical properties were affected negatively. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

The Hypercube Separation algorithm: A fast and efficient algorithm for on-line handwritten character recognition

This paper introduces a new neural network training algorithm, Hypercube Separation (HCS) algorithm which is very fast and guaranteed to learn. HCS is a simple algorithm suitable for hardware implementation which classifies different input patterns presented to it through the formation of multiple hyperplanes. The performance of the HCS algorithm is compared to that of the Binary Synaptic Weights (BSW) algorithm and to the Backpropagation (BP) algorithm in solving the two spiral problem, which is an almost pathological problem for pattern separation. The HCS algorithm was able to successfully separate the input patterns, requiring three orders of magnitude less training time than the BP algorithm and one order of magnitude less hidden layer nodes than the BSW algorithm. We also present the application of HCS to on-line handwritten character recognition with good results, especially when the simple nature of the algorithm is taken into consideration.     

Suction Removal of Sediment from between Armor Blocks. II: Waves

When a stone/armor layer on a sand bed is exposed to flow, the sand underneath will be agitated by the flow turbulence. When the flow velocity reaches a critical value, the sand will be sucked (winnowed out) from between the armor blocks. In a previous investigation, we studied suction removal of sediment in steady currents. The present study is an extension of our previous investigation to waves. The critical condition for the onset of suction is determined. It is found that the onset of suction is governed by three parameters: (1) the sediment mobility number (based on the sediment size); (2) the ratio of sediment size to stone size, d/D; and (3) the Keulegan-Carpenter (KC) number, based on the armor block/stone size. The variation of the critical mobility number for suction as a function of d/D and KC is determined for the ranges of the parameters 0.001相似文献   

Hydrolysis characteristics of calcium hydride (CaH2) powder in the presence of ethylene glycol,methanol, and ethanol for controllable hydrogen production

Calcium hydride (CaH₂) reacts vigorously with water, liberating hydrogen gas. For the development of an effective hydrogen storage system, it is an absolute necessity to control the rate of hydrogen production. In the present study, the effects of different solvent, ethylene glycol, methanol, and ethanol, on the hydrolysis of CaH₂ for controllable hydrogen production were investigated. Reactions were performed at different temperatures (20, 40, and 60°C) in order to calculate the kinetic parameters. The Arrhenius equation was used to calculate the activation energies. The activation of energy of the hydrolysis reaction of CaH₂ in an ethanol solution (E_a = 20.03 kJ/mol) was found to be less than the other reactions.     

Electron–Electron Interactions in Sb-Doped SnO<Subscript>2</Subscript> Thin Films

Electrical conductivity and Hall-effect measurements on undoped and Sb-doped SnO₂ thin films prepared by the sol–gel technique were carried out as a function of temperature (55 K to 300 K). Structural characterizations of the films were performed by atomic force microscopy (AFM) and x-ray diffraction (XRD). A doping-induced metal–insulator transition (MIT) was observed. On the metallic side of the transition, the experimental data were interpreted in terms of electron–electron interactions (EEI). The existence of EEI was confirmed by excellent agreement between theoretical and experimental data. The experimental data on the insulator side of the transition were analyzed in terms of variable-range hopping (VRH) conduction. A complete set of parameters describing the properties of the localized electrons, including hopping energy, hopping distance, and the value of the density of states at the Fermi level, was determined.     

Synthesis,structural characterization,and hydrolysis of Ammonia Borane (NH3BH3) as a hydrogen storage carrier

In the present study, synthesis, structural characterization, and hydrolysis of the promising hydrogen storage carrier ammonia borane (NH₃BH₃), were investigated. NH₃BH₃ was prepared by one-pot chemical reaction between sodium borohydride (NaBH₄) and different ammonia salts [NH₄X, X: SO₄, CO₃, Cl] in the presence of solvent, tetrahydrofurane (THF). Synthesizes with different temperatures (20–40 °C), reaction times (30–130 min), amount of added THF volume (50–200 ml) and NaBH₄/(NH₄)₂SO₄ input molar ratios (0.47–0.75) were performed in order to find the optimum reaction conditions for obtaining maximum product yield. The characterization of NH₃BH₃ products was carried out by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy (RS), elemental analysis (C, H, N, O) and NMR spectroscopy. Characterization results indicated that NH₃BH₃ as a crystalline powder at 98% purity was achieved with 92.18% production yield. Additionally, hydrolysis of product NH₃BH₃ in the presence of amorphous Co–B catalyst at 22–80 °C under magnetic stirring (700 rpm) was performed. The maximum hydrogen generation rate was 5447.80 ml min⁻¹ g cat⁻¹ and the hydrolysis reaction kinetics were clarified based on zero-order, first-order and Langmuir–Hinshelwood kinetic models.     

Baking kinetics of muffins in convection and steam assisted hybrid ovens (baking kinetics of muffin…)

Effects of oven type and baking temperature on acrylamide concentration, surface browning, temperature profiles and drying rates of muffins were investigated. Muffins were baked in convection and steam assisted hybrid ovens at 145, 160 and 175 °C for different baking times. For all oven types, the acrylamide concentration of muffins increased with increasing baking time and temperature (p < 0.05). The formation was considered as the first order reaction kinetics except for the lowest baking temperature at natural convection and steam assisted hybrid ovens. The reaction rate constant, k was found to be in the range of 0.027–0.078 (min⁻¹). For the forced convection oven, the effect of baking temperature on acrylamide concentration followed the Arrhenius type of equation; with activation energy of 36.35 kJ/mol. The minimum drying rate was observed by the steam assisted hybrid oven, at all conditions. Steam assisted baking resulted in lower acrylamide concentration at all baking temperatures, while providing the average moisture content not significantly different.     

Control of lactic acid bacteria in fermented beverages using lysozyme and nisin: test of traditional beverage boza as a model food system

The objective of this study was to increase quality and limited shelf‐life of boza (3–15 days), a traditional Balkan origin fermented beverage using lysozyme (LYS) and/or nisin (NIS). For this purpose, the effectiveness of NIS, LYS and LYS:NIS combinations was first tested in a broth medium at 4 °C for 3 weeks on Lactobacillus plantarum, one of the frequently isolated lactic acid bacteria in boza. Stability of LYS and NIS in boza, their effects on LAB counts, and chemical and sensory properties of boza were then evaluated during cold storage at 4 °C. Results of LAB counts as well as pH, d ‐ and l ‐lactic acid, and titratable acidity measurements showed that LAB in boza containing NIS (250 μg g^?1) or LYS:NIS (500:250 μg g^?1) could be controlled without reducing LAB counts below 6 log CFU mL^?1 during 2 weeks shelf‐life. In contrast, LYS (500 μg g^?1) alone could not control LAB in boza to delay its acidic spoilage. Positive effects of NIS and LYS:NIS application on quality of boza were also proved with sensory analysis by panelists and e‐nose measurements. This work showed that use of natural GRAS agents in preservation of fermented beverages containing probiotic LAB is possible without affecting their characteristic aroma and flavour.