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31.
YANBIN LI MICHAEL F. SLAVIK CARL L. GRIFFIS JEONG-WEON KIM 《Journal of Food Safety》1993,13(4):241-252
Electrical stimulation was evaluated as a method to kill Salmonella typhimurium in various salt solutions at different concentration . Salmonella typhimurium at 2 × 105 CFU/ml was treated at 22–24C for 60 min in each salt solution using electricity at 10 mA/cm2 current, 1 kHz frequency, and 50% duty cycle. Samples taken at various times were serially diluted, plated on tryptic soy agar and xylose lysine desoxycholate agar, and incubated at 37C for 18–24 h. To detect injured cells, samples were also pre-enriched in buffered peptone water at 37C for 4–5h before being plated. Results indicated all salmonellae were electrically killed at 5 min in NaCl, at 30 min in NaNO3 , and at 45 min in NaC2 H3 O2 at 0.15 and 0.015 M concentrations. Salmonellae were also killed at 45 min in Na3 PO4 and at 60 min in Na2 CO3 at 0.0015 M concentration by electricity in combination with high pH . 相似文献
32.
A novel approach is proposed for improving adaptive feedback cancellation using a variable step-size affine projection algorithm(VSS-APA) based on global speech absence probability(GSAP).The variable step-size of the proposed VSS-APA is adjusted according to the GSAP of the current frame.The weight vector of the adaptive filter is updated by the probability of the speech absence.The performance measure of acoustic feedback cancellation is evaluated using normalized misalignment.Experimental results demonstrate that the proposed approach has better performance than the normalized least mean square(NLMS) and the constant step-size affine projection algorithms. 相似文献
33.
Cloud computing is becoming a key factor in the market day by day. Therefore, many companies are investing or going to invest in this sector for development of large data centers. These data centers not only consume more energy but also produce greenhouse gases. Because of large amount of power consumption, data center providers go for different types of power generator to increase the profit margin which indirectly affects the environment. Several studies are carried out to reduce the power consumption of a data center. One of the techniques to reduce power consumption is virtualization. After several studies, it is stated that hardware plays a very important role. As the load increases, the power consumption of the CPU is also increased. Therefore, by extending the study of virtualization to reduce the power consumption, a hardware-based algorithm for virtual machine provisioning in a private cloud can significantly improve the performance by considering hardware as one of the important factors. 相似文献
34.
提出了一种计算公式,定量地计算了既有氢氧化物沉淀又有氢氧配离子形成的化学反应体系中的金属离子的分布,考察了影响沉淀和配离子形成的各种因素.基于提出的公式,计算了锌、镉、铜、镍、铁(Ⅲ)、铁(Ⅱ)、铝、钙、镁的沉淀率,理论计算与实验结果一致. 相似文献
35.
YONG KANG PYUNG S. SONG JONG S. YUN YI Y. JEONG SANG D. KIM 《Chemical Engineering Communications》2013,200(1):31-47
Effects of secondary air injection on the hydrodynamics such as solid holdup and gas-solid flow behavior were investigated in a circulating fluidized bed. The gas velocity in the riser, the ratio of secondary air velocity to that of primary air, and the solid circulating rate were chosen as operating variables. Fluid cracking catalyst(FCC) with a density of 1840 kg/m3 and a mean diameter of 74 um was employed as the solid phase. The secondary air was fed to the riser radially or tangentially at the wall of the column. Pressure drop fluctuations in the riser were measured and analyzed by adopting the stochastic method to characterize the effects of secondary air injection on the gas-solid flow behavior in the bed. It has been found that the injection of secondary air into the riser can increase the solid holdup in the riser considerably, and that the tangential injection of secondary air is more effective for the increasing the solid holdup than the radial injection. However, the gas-solid flow behavior has been found to become less persistent with the injection of secondary air; the resultant flow behavior is more complex when the air is injected tangentially than radially. The solid holdups in the primary as well as secondary zones of the riser have been well correlated in terms of not only operating variables but also fractal dimension of the pressure fluctuations. 相似文献
36.
Silica beads, containing 2-hydroxy-5-nonylacetophenoneoximc (LIX84) were prepared in order to examine the removal of copper ions from aqueous waste solutions. The process for copper ion removal using the modified silica beads was mathematically modeled using both a non-equilibrium model and an equilibrium model. The external mass transfer coefficient and effective diffusivity inside the bead pore were estimated by matching the experimental data and predicted values from the model, and the results were compared. The results of the two models were similar and in good agreement because of the relatively faster reaction rate than mass transfer rate. Sensitivity analyses showed that the external mass transfer has more influence on the copper ion removal system because of hydrophobic effects. 相似文献
37.
Steady, single-phase transport characterized by high eddy diffusivity in axial direction is a special case of vessel transport phenomena which has not been studied systematically so far. In the present paper, experiments are reported for a Gorter-Mellink duct, at zero net mass flow, covering turbulent eddy transport in cold He4 pressurized beyond its thermodynamic critical pressure above 4 K. Axial transport in vertical direction is induced by gravitational buoyancy. A new phenomenological equation is proposed on the basis of quantum fluid convection postulated originally for He II below the lambda point (Goner and Mellink, 1949). Our data agree reasonably with the equation. 相似文献
38.
The phase behaviors of toluene/polycyclic aromatic hydrocarbon mixture systems were investigated with a continuous-flow type apparatus at 573.2,598.2.623.2 and 648.2K,while the pressure changed from 1 tp 5 MPa,The pseudo-binary phase behaviors were predicted with the Peng-Robinson equation of state with interaction parameters between toluene and pseudo-components considered.The phase diagrams of the system have been classified following the category of phase boundary diagram models.The extraction selectivity and efficiency of toluene as a solvent was discussed by comparing with that of hexane .The prediction model for selectivity was also suggested. 相似文献
39.
In this paper we introduce a new test of the null hypothesis of no cointegration between a pair of time series. For a very simple generating model, our test compares favourably with the Engle–Granger/Dickey–Fuller test and the Johansen trace test. Indeed, shortcomings of the former motivated the development of our test. The applicability of our test is extended to series generated by low-order vector autoregressions. Again, we find evidence that this general version of our test is more powerful than the Johansen test. The paper concludes with an empirical example in which the new test finds strong evidence of cointegration, but the Johansen test does not. 相似文献
40.