Part-baked rye bread with and without Ca-propionate (0.2 g/100 flour) were baked for 10, 15, 20 minutes at 230°C and stored at refrigerator temperature (4°C) for 10, 20, 30 days then second-baked for 5, 10, 15 minutes at the same temperature to give an oven-fresh end product. The effect of antimicrobial additive (Ca-propionate), part-baking, storage in refrigerator and rebaking on quality parameters such as yield of volume and crumb softness, water activity and pasting properties of rye bread crumb was evaluated. Addition of Ca-propionate increased bump area, while yield of volume and softness values of rye bread crumb decreased. The increase in initial baking time caused a decrease in the pasting temperature, water activity, and softness value and an increase in the bump area and viscosity of the rebaked bread crumb. Bump area and pasting temperature of rebaked rye bread crumb increased with longer (intermediate storage) time, while viscosity, yield of volume, water activity, and softness values decreased. A strong negative correlation was observed between pasting temperature and other parameters, which are bump area, peak viscosity, holding end viscosity, cooling end viscosity, and softness value for rye bread that was rebaked after part-baked and storing at refrigerator temperature. The re-baking rye bread after part-baking for 10 and 15 minutes and storage for 7, 14, and 21 days at refrigerator temperature gave softer crumb than the control group. 相似文献
In this paper a mode II fracture testing method has been developed for wood from analytical, experimental and numerical investigations. Analytical results obtained by other researchers showed that the specimen geometry and loading type used for the proposed mode II testing method results in only mode II stress intensity and no mode I stress intensity at the crack tip. Experiments have been carried out to determine mode II fracture toughness KIIC and fracture energy GIIF from the test data collected from both spruce (pice abies) and poplar (populus nigra) specimens. It was found that there existed a very good relation between fracture toughness KIIC and fracture energy GIIF when the influence of orthotropic stiffness EII* in mode II was taken into account. It verified that for this mode II testing method the formula of LEFM can be employed for calculating mode II fracture toughness even for highly orthotropic materials like wood. In the numerical studies for the tested spruce specimen, the crack propagation process, stress and strain fields in front of crack tips and the stress distributions along the ligament have been investigated in detail. It can be seen that the simulated crack propagating process along the ligament is a typical shear cracking pattern and the development of cracks along the ligament is due to shear stress concentrations at the crack tips of the specimen. It has been shown that this mode II fracture testing method is suitable for measuring mode II fracture toughness KIIC for highly orthotropic materials like wood. 相似文献
Several fragile watermarking schemes presented in the literature are either vulnerable to vector quantization (VQ) counterfeiting attacks or sacrifice localization accuracy to improve security. Using a hierarchical structure, we propose a method that thwarts the VQ attack while sustaining the superior localization properties of blockwise independent watermarking methods. In particular, we propose dividing the image into blocks in a multilevel hierarchy and calculating block signatures in this hierarchy. While signatures of small blocks on the lowest level of the hierarchy ensure superior accuracy of tamper localization, higher level block signatures provide increasing resistance to VQ attacks. At the top level, a signature calculated using the whole image completely thwarts the counterfeiting attack. Moreover, "sliding window" searches through the hierarchy enable the verification of untampered regions after an image has been cropped. We provide experimental results to demonstrate the effectiveness of our method. 相似文献
Measurements were made on the longitudinal and transverse strain of sea-ice beams loaded in flexure. The specimens were tested with stress rates varying from 10 to 600 kPa s?1 and temperatures ranging from ?5°C to ?40°C. Under these conditions, the effective strain ratio μ increases with increasing temperature and decreasing stress rate. The strong influence of the stress rate, σ, suggests an empirical law of the form: μ = 0.24 where σ is the stress rate (kPa s?1), is a unit stress ratio (1 kPa s?1) and μD is a dynamic value of Poisson's rate which depends on the temperature. 相似文献
A large sea water desalination plant, using the multi-effect process at high temperature has been described and a comparison is given with the other distillation processes.The multi-effect plant is easily adaptable in a wide range of operating conditions. It has a low total energy consumption (8.75 KWh per m3 produced (expressed as electrical energy). A high GOR is obtained (12.4). Compared with a MSF of the same production capacity, the investment costs are smaller. This leads to a substantial decrease in cost of the produced water. The technology of horizontal sprayed tubes is a proven one and has been executed more than a hundred times on small and medium units. 相似文献
A steel for concrete oxidizes in humid air to give lepidocrocite γ Fe OOH (orthorhombic) and Geothit Fe OOH (orthorhombic). When a test piece of reinforced concrete (or mortar), wetted with a saline solution, is submitted to an electromotive force (accelerated corrosion) the nature of the hydrated iron oxides formed is distinct: in the case of the use of a NaCl and KCl solution, akaganeite β Fe OOH (tetragonal) essentially appears; with a Na2SO4 solution, goethit and γ Fe2O3 are obtained on the steel. These differences in the cristallographic nature of the oxides, and consequently the crystal growth process associated with their formation, are related to the time at which the first macroscopic crack in the test piece appears.
Abstract
Un acier pour béton armé s'oxyde à l'air humide pour former de la lepidocrocite FeOOH γ orthorhombique et de la goethite FeOOH également orthorhombique. Si on soumet une éprouvette de béton (ou de mortier) armé, imbidé d'une solution saline, à une force électromotrice appliquée, afin de réalizer une corrosion accélérée de l'armature, on constate que la nature des oxydes de fer hydratés formés est assez particulière: dans le cas de l'utilisation de solution de NaCl ou de KCl il se forme essentiellement l'akaganeite FeOOH β tétragonale; avec une solution de Na2SO4 on obtient de la goethite et du Fe2O3 γ. Ces différences dans la nature cristallographique des oxydes formés, donc les processus de croissance cristalline qui leur donnent naissance peuvent expliquer les résultats des études électrochimiques (échéance d'apparition de la première fissure macroscopique). 相似文献