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51.
Vicente M. Gómez-López María I. Gil Ana Allende Jeroen Blancke Lien Schouteten María V. Selma 《Food and Bioprocess Technology》2014,7(12):3390-3397
The fresh-cut industry must treat process water to guarantee its microbial quality before reuse or recirculation back into the processing line. In the present study, the suitability of high-power ultrasound (HPU) for disinfecting and recycling process water was evaluated. An ultrasonic horn (20 kHz) was used to inactivate Escherichia coli O157:H7 inoculated in five types of process water which showed different physical and chemical characteristics. Differences in the inactivation level of E. coli O157:H7 at different HPU densities (0.14, 0.28, 0.56, and 1.12 kW/L) with controlled (20–25 °C) and uncontrolled (15–72 °C, 3.6 °C/min) temperature increase were studied. Results showed that the higher the power density and temperature, the higher the efficiency, reaching up to 6 log reductions of E. coli O157:H7. Alkalinity (between 0 and 253 mg HCO3 ?/L) and organic matter concentration (between 9 and 3,525 mg O2/L) in water did not reduce ultrasonic efficacy against E. coli O157:H7. Agglomerates >90 μm, which represented 34 % of those present in the process water, were reduced to only 11 % by HPU. Results indicate that HPU can be successfully applied to treat process water of the fresh produce industry because the antimicrobial efficacy was not affected by the continuous variation of the process water quality. HPU can be a suitable technology for the fresh produce industry to be able to reduce consumption of water and decrease wastewater and the generation of disinfection by-products. 相似文献
52.
M. Vicente da Silva A. N. Antão 《International journal for numerical methods in engineering》2012,89(12):1471-1496
This paper describes a novel upper‐bound formulation of limit analysis. This formulation is an innovative variant of an existing two‐field mixed formulation based on the augmented Lagrangian method also developed by the authors. A natural approach is used to describe the deformation of each finite element. Furthermore, and in contrast to the previous formulation, two independent field approximations are now both used to define the velocity field, defined globally and at element level. It is shown that this feature allows a governing system of uncoupled linear equations to be obtained. Some numerical examples in plane strain conditions are presented in order to illustrate the current model performance. In conclusion, the potential and advantages of this new approach are discussed. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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A. V. Berezin A. V. Vorontsov S. V. Zakharov M. B. Markov S. V. Parot’kin 《Mathematical Models and Computer Simulations》2013,5(5):492-500
A mathematical model of electron cascade transfer is presented. It is developed for studying the prebreakdown stage of gaseous discharge based on the kinetic equation for electrons in a self-consistent electromagnetic field. An elastic scattering of electrons, excitation of molecules by electron impact, and impact ionization are taken into account. A natural ionization background is used as the initial distribution of free electrons. The results of the computational experiment are compared to the data of measurements of drift velocity and the average energy of electrons of discharge, as well as the Townsend coefficient in a flat charged condensor filled with diluted xenon. The comparison showed that the model is not in contrast with the experiment. In order to contract the volume of the discharge’s full current calculation, a transport approximation is built. It is based on the averaging of angular scattering. The applicability of the transport approximation for modeling the full current of the capillary discharge is studied. 相似文献
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João Vicente Akwa Horácio Antonio Vielmo Adriane Prisco Petry 《Renewable & Sustainable Energy Reviews》2012,16(5):3054-3064
This paper presents a review on the performance of Savonius wind turbines. This type of turbine is unusual and its application for obtaining useful energy from air stream is an alternative to the use of conventional wind turbines. Simple construction, high start up and full operation moment, wind acceptance from any direction, low noise and angular velocity in operation, reducing wear on moving parts, are some advantages of using this type of machine. Over the years, numerous adaptations for this device were proposed. The variety of possible configurations of the rotor is another advantage in using such machine. Each different arrangement of Savonius rotor affects its performance. Savonius rotor performance is affected by operational conditions, geometric and air flow parameters. The range of reported values for maximum averaged power coefficient includes values around 0.05–0.30 for most settings. Performance gains of up to 50% for tip speed ratio of maximum averaged power coefficient are also reported with the use of stators. Present article aims to gather relevant information about Savonius turbines, bringing a discussion about their performance. It is intended to provide useful knowledge for future studies. 相似文献
58.
Ferrofluid Lubrication of Compliant Polymeric Contacts: Effect of Non-homogeneous Magnetic Fields 总被引:1,自引:0,他引:1
This paper demonstrates a new route to control friction in the isoviscous elastic lubrication regime between compliant point contacts. For this aim, the superposition of non-homogeneous magnetic fields in ferrofluid lubricated contacts is proposed. Under appropriate conditions, a friction reduction is observed by simply displacing the magnetic field distribution in the flow direction towards the inlet of the contact. This friction reduction is associated with a lower Couette friction contribution as a result of the fact that surfaces become more separated under field. Experiments and simulations are in good qualitative agreement. 相似文献
59.
Vicente Milanés Joshué Pérez Jorge Godoy Enrique Onieva 《Expert systems with applications》2012,39(10):9097-9107
To decrease traffic accidents is a declared target of Intelligent Transportation Systems (ITS). Among them, rear-end collisions are one of the most common and constitute one of the as yet unsolved topics in the automotive sector. This paper presents an approach to the avoidance of rear-end collisions in congested traffic situations. To this end, two fuzzy controllers, a Collision Warning System (CWS) and a Collision Avoidance System (CAS), have been developed. The former is in charge of alerting the driver in case of an impending rear-end collision to prevent or mitigate the crash. The latter is in charge of generating an output control signal for the steering wheel in order to avoid the collision. Both CWS and CAS have been tested with real cars using vehicle-to-infrastructure (V2I) communications to acquire data of vehicles. A system installed in the infrastructure capable of assessing road traffic conditions in real time is responsible for transmitting the data of the vehicles in the surrounding area. The systems have been tested at the Center for Automation and Robotics (CAR)’s facilities with two mass-produced cars. 相似文献
60.
Víctor Falguera Anabel Mengual Manuel Vicente Albert Ibarz 《Food research international (Ottawa, Ont.)》2010,43(3):882-885
Calcium pidolate is a calcium containing molecule that has the essential advantage of being absorbed more easily and in a greater proportion than any other calcium compound. The combination between a low methoxyl pectin and calcium allows forming food gels with a small amount of sugar. In this work, the use of calcium pidolate in the composition of two of these products (jams and gelatins) has been assayed, testing its rheological properties. An optimum content of calcium pidolate has been found for each product and sugar proportion. Both in jams and gelatins, the results obtained with calcium pidolate were better than the ones obtained with calcium chloride. 相似文献