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Singularity Study of Sectorial Domain by Weak Formulation and Fractal Finite Element in Hamilton System
Get PDFThe weak formulation of mixed state equations including boundary conditions are presented in polar coordinate system, mixed variational formulation is established in sectorial domain. The fractal finite element method is used to analyse the sector domain problem. The present result is exactly analogous to the Hamiltonian mechanics for a dynamic system by simulating time variable t with coordinate variable r. The stress singularity at singular point is investigated by means of the fractal finite element method. The present study satisfies the continuity conditions of stresses and displacements at the interfaces. The principle and method suggested here have clear physical concepts. So this method would be easily popularized in dynamics analysis of elasticity
Buckling Behavior of Steel Plates and Concrete Filled Composite Shear Walls Related Nuclear Power Engineering
Get PDFBased on the program of nuclear power engineering, the in-plane buckling behavior of Steel plates and concrete filled composite shear wall (SCSW) was investigated. 9 1/5 scaled specimens were conducted under horizontal cyclic load and constant vertical load. The parameters such as the space of studs, the vertical load, the form of connectors, and the thickness of the steel plate were designed to research the affection on the buckling of the steel plate. According to the results of tests, it can be seen that the bulge of the steel plate occurred at about 50mm above the top of the foundation beam. The bulge can be connected as a whole in the specimens with studs only, but not in the specimens with stiffeners. Finite element models were performed to simulate the buckling behavior of the steel plate, and the results were found to be in good agreement with the test results. The buckling stress of the steel plate was calculated by equations based on the measuring data. It was found that they were smaller than that of finite element analysis. The more accurate simulation was needed
Technological Activities and Antibiofilm Effect of Staphylococcus Equorum Isolated from Fermented Sausage
Get PDFThe present study aimed at evaluating the technological properties and the ability of Staphylococcus equorum to inhibit biofilm formation by Staphylococcus aureus and Escherichia coli O157:H7. Seventeen S. equorum strains were isolated from fermented sausage and examined for their ability to grow at 10 or 15 ºC in the presence of 10 or 15% NaCl at pH values of 4.5, 5.0 or 5.5. Technological properties including catalases, superoxide dismutase, lipolytic and proteolytic activities of S. equorum strains were determined. All strains grew under the studied conditions and showed variable activities. The strain S. equorum HMA4 showed good characters of all the studied metabolic properties and had ability to grow under all studied conditions. The antagonistic effect of S. equorum HMA4 against S. aureus or E. coli O157:H7 biofilms was studied under the above conditions. There was a significant increasing in the reduction percentage of biofilm formation at pH 5.0 and 5.5 comparing with those obtained at pH 4.5. The antibiofilm effect of S. equorum HMA4 against E. coli O157:H7 was higher than its effect on biofilm of S. aureus. In conclusion, beside its role in the developing flavor and enhancing the color of the fermented foods, S. equorum HMA4 could be used as a protective starter against some foodborne pathogens in fermented foods
Influence of Carding and Pressing on Hygrothermal Properties and Fire Reaction of Hemp Fiber Nonwoven Mats
Get PDFThis article depicts the effect of carding and pressing on hygrothermal properties of hemp fibers nonwoven mats, trying to understand if their implementation can improve their behavior when employed as insulation materials in buildings. Hemp fibers belonging to Cannabis Sativa species and coming from local area (Apulia - Italy) were examined, then samples of carded and pressed hemp fibers nonwoven mats were prepared. According to European standards, the thermal conductivity, the vapor permeability and the fire reaction of hemp fibers samples were measured. Results were compared to each other and with those of a commercial nonwoven mat made with hemp (90 wt. %) and synthetic fibers (10 wt. %), used as reference. We observed that carded and pressed hemp fibers were characterized by a lower thermal conductivity when compared to unprocessed hemp fibers, likely because the removing of wood elements. On the other hand, not processed hemp fibers show higher breathability when compared to carded and pressed ones, as well as with respect to the commercial nonwoven mat. Moreover, it was proved that the absence of synthetic commingled fibers in hemp fibers allows a better behavior in fire reaction. At last, the improvement in terms of insulation properties of a hollow brick when filled with hemp fibers was verified, by comparing the thermal conductivities of an empty and a filled hollow brick; as expected, the filled hollow brick shows a lower thermal conductivity, underlining the effectiveness of hemp fibers as insulation material
Fabrication and Characterization of Magnetic GQDs Using Green Tea Extract for Environmental Remediation
Get PDFA graphene-based magnetic nanocomposite was synthesized and used as an effective adsorbent for crystal violet dye. The properties of the magnetic nanocomposite were characterized by X-ray diffraction (XRD), Fourier Transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and Vibrating Sample Magnetometer (VSM). This novel graphene-based magnetic nanocomposite showed great adsorptive ability towards the analytes and can easily separated from the water. When the amount of magnetic GQDs was 10 g/L, the removal rate of was more than 90%
Effects of Resveratrol on Superficial Scald of 'Dangshansuli' Pears
Get PDFThe effects of resveratrol (Res) on the quality and superficial scald of ‘Dangshansuli’ pears (Pyrus bretchnederi Rehd.) during cold storage (0±0.5°C) and shelf life (20°C) were investigated. The results showed that treatments with 0.1, 1.0, 10 and 100 mg L-1 Res significantly delayed the decrease of firmness, soluble solids contents (SSC), juice rate, reduced the relative conductivity, MDA, α-farnesene and conjugated trienes in the cold storage. At the end of 210 d storage, α-farnesene of control, 0.1, 1.0, 10 and 100 mg L-1 Res treatments were 14.81, 11.0, 10.49, 9.31 and 11.4 nmol cm-2, respectively. Whereas conjugated trienes were 6.38, 4.17, 4.04, 3.67 and 4.39 nmol cm-2 respectively. After 210 d, the scald incidence of control, 0.1, 1.0, 10 and 100 mg L-1 Res treatment were 45.5%, 4.3%, 0%, 0% and 7.1%, respectively, and their scald index were 18.2%, 2.9%, 0%, 0% and 3.1%, respectively. After additional 7 d at 20°C, scald incidence successively were 100%, 21.4%, 22.4%, 14.1% and 20.9%, while the scald index were 71.2%, 23.3%, 22.9%, 15.4% and 22.8%, respectively. Res treatments maintained the quality and inhibited superficial scald, and 10 mg L-1 Res was the optimum treatment. Thus, it is likely that Res can serve as a potential antioxidant for the preservation and storage of postharvest ‘Dangshansuli’ pears
Determination of Catechol by Cetyltrimethylammonium Bromide Functionalized Graphene Modified Electrode
Get PDFA simple and sensitive electrochemical sensor was prepared by using electrodeposition of the cetyltrimethylammonium Bromide (CTMAB ) functionalized Graphene (GR) on the glassy carbon electrode (GCE) to determine Catechol (CC) in water. The performance of the CTMAB functionalized GR sensor was studied and the analysis conditions of the CC were optimized. The experimental results showed that, compared with bare GCE, the redox peak current of CC on the modified electrode was obviously enhanced. Under the optimized conditions, the oxidation and reduction peak current all showed a good linear relationship with the concentration of CC from 5μmol/L to 1000 μmol/L. The detection limit of oxidation peak is 2.92 μmol/L, and that of reduction peak is 2.44 μmol/L. The recovery was founded to be in the range of 92.70 %~101.80 %. Moreover, the sensor could be used for the determination of CC in real samples with satisfactory results. And the mechanism of the sensitization of CC detected by CTMAB-GR modified GCE was discussed preliminarily
Au25 cluster-loaded SrTiO3 water-splitting photocatalyst; preparation and elucidation of the effect of cocatalyst refinement on photocatalytic activity
Get PDFWater-splitting photocatalysts have attracted much attention for decades as materials to produce clean and renewable hydrogen (H2) as a fuel. In this study, we succeeded in precisely loading ultrafine gold cocatalyst particles (Au25 clusters) on the water-splitting photocatalyst SrTiO3 using glutathionate-protected Au25 clusters as a precursor. Photocatalysis experiments using the obtained photocatalyst revealed that the ultraminiaturization of the Au cocatalyst on SrTiO3 improves its water-splitting activity. The main reason for this improvement was attributed to the acceleration of the H2-evolution reaction caused by the ultra-miniaturization of the cocatalyst. This effect of refining the cocatalyst differs from that of Au-loaded BaLa4Ti4O15. These results demonstrate that the effect of ultra-miniaturization of the cocatalyst on photocatalytic activity varies depending on the photocatalyst
Stability analysis and observer design for one-sided Lipschitz descriptor systems with time-varying delay
Get PDFThis paper investigates the problem of stability analysis and observer design for nonlinear descriptor systems with time-varying delay. In the systems, the nonlinear function satisfies the one-sided Lipschitz condition and the quadratic internal boundary condition. The disturbance is considered in both the state and the output equation. Using one-sided Lipschitz condition, the quadratic internal boundary condition, and the generalized Lyapunov method, we establish the non-strict bilinear matrix inequality (BMI)-based condition. We change the condition into strict bilinear matrix inequality (BMI) condition. Furthermore, we give the linear matrix inequality-based condition to ensure the gradual convergence of state estimation error and to accomplish robustness against L2 norm bounded disturbances by utilizing change of variables for straight forward computation of the observer gain matrix. Finally, a numerical example is given to verify the effectiveness of the observer design scheme
Optimization of Dietary Fiber Extraction from Pineapple Pomace by Response Surface Methodology
Get PDFTaking pineapple peel as raw material, the dietary fiber in pineapple pomace was extracted by enzymatic method combined with the chemical chemicalchemicalchemical chemical method. The effects of enzyme dosage, enzymolysis timetimetimetime, alkaline pH and alkali solution time on the yield of pineapple pomace dietary fiber were studied. And optimize the extraction process. The results showed that the optimal extraction process parameters of pineapple pomace were as follows: enzyme dosage 480u/g, enzyme hydrolysis time 43 minute, alkaline hydrolysis pH=12, alkaline hydrolysis time 60 minute, pineapple pomace dietary fiber under these conditions, the yield can reach 78.86%. The mathematical model is feasible for optimizing the extraction process of pineapple pomace dietary fiber