Tensile strength of radio frequency cold plasma treated PET fibers - Part 1: Influence of environment and treatment time

This article reports on a series of experiments with polyethylene terepthalate (PET) treated in a radio frequency plasma reactor using argon and oxygen as a gas fuel, for treatment times equal to 5 s, 20 s, 30 s, and 100 s. The mechanical strength modification of PET fibers, evaluated by tensile tests on monofilaments, showed that oxygen and argon plasma treatment resulted in a decrease in the average tensile strength compared with the untreated fibers. This reduction in tensile strength is more significant for argon plasma and is very sensitive to the treatment time for oxygen plasma. Scanning electron microscopy (SEM) used to analyze the effects of cold plasma treatment on fiber surfaces indicates differences in roughness profiles depending on the type of treatments, which were associated with variations in mechanical strength. Differences in the roughness profile, surveyed through an image analysis method, provided the distance of roughness interval, D-ri. This parameter represents the number of peaks contained in a unit length and was introduced to correlate fiber surface condition, before and after cold plasma treatments, and average tensile strength. Statistical analysis of experimental data, using Weibull cumulative distribution and linear representation, was performed to explain influences of treatment time and environmental effects on mechanical properties. The shape parameter, alpha, and density parameter, beta, from the Weibull distribution function were used to indicate the experimental data range and to confirm the mechanical performance obtained experimentally.

Effects of thermal annealing on the semi-insulating properties of radio frequency magnetron sputtering-produced germanate thin films

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Remote laboratory experiment access via an RFID interface

In this paper, remote laboratory experiment access is considered through the use of radio frequency identification (RFID) technology. Contactless smart cards are used widely in many applications from travel cards through to building access control and inventory tracking. However, their use is considered here for access to electronic engineering experimentation in a remote laboratory setting by providing the ability to interface experiments through this contactless (wireless) connection means. A case study design is implemented to demonstrate such a means by incorporating experiment data onto a contactless smart card and accessing this via a card reader and web server arrangement. © 2012 IEEE.

Desenvolvimento de um sintetizador de freqüência de baixo custo em tecnologia CMOS

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Estudo da tecnologia RFID e sua aplicação na gestão de estoques

Due to the need of more agility, dynamism and reliability in stock management, the market has turned its attention to RFID, which offers a practical solution and live up to the big corporations' expectations. The search for continuous improvement establishes a direct link with RFID, for its technology offers accurate real time information in any monitored given place. RFID is a radio frequency communication technology. A reader communicates to a tag through waves. This tag can be active, with a battery, or passive, in which its power is supplied by currents induced by the field variation it is exposed to. The RFID technology has a well defined basic principle, but there are many constructive ways of implementing it. The adaptability as well as the flexibility regard to the several kinds of stock in industry, reaching their particular needs. RFID can lower maintenance costs in stock by collecting data more accurately, lowering human error and optimizing the item handling at its reception, exit and while it is inside the company. This paper presents an example of RFID technology applied in a company's stock management. It is possible to prove that there are, in fact, great advantages in implementing this technology, as it creates the opportunity for continuous improvement in stock management, with better application of material, labour and quality tools, since the data collected through an automatized process using RFID are more reliable and dynamic

Avaliação de projetos logísticos de RFID aplicados na indústria aeronáutica brasileira

Pós-graduação em Engenharia Mecânica - FEG

Concept design for a RFID enabled student workbook

In this paper, the concept for a radio frequency identification (RFID) enabled student workbook is discussed and a prototype system developed. The workbook is a question-answer notebook in traditional paper format in which hand written solutions to student assignments are written. An embedded RFID tag in the workbook is then used for the student to store his/her solution to the attempted assignment questions at home. On entry to the classroom and once the questions have been attempted, an RFID reader in the classroom will retrieve the answers from the workbook, automatically collate the results and instantly provide a summary of these results for the individual student and the class as a whole. If problems are highlighted, the teacher can then investigate issues with individual students and review the answers provided in the workbook.

Contribuições para a melhoria da gestão de resíduos de eletroeletrônicos no Brasil, no contexto da sustentabilidade ambiental

Pós-graduação em Engenharia de Produção - FEG

Módulo para identificação de objetos e transmissão de dados sem fio

Pós-graduação em Engenharia Elétrica - FEIS

Estimativa do padrão de preferência térmica de matrizes pesadas (frango de corte)

Female broiler breeder productivity is based on the principles of thermal comfort that are directly related with the microclimate inside the housing. This research had the objective of monitoring the behavior of female broiler breeders, using the technology of radio-frequency, injectable transponders and readers in different existing microclimates inside a small scale distorted housing model. Eight birds with electronic identification were used. Three readers were used, in three different points inside the model: on the floor of the nest, in the passage besides the lateral wall and below the water facility. Dry bulb (DBT), wet bulb (WBT) and black globe (BGT) temperature were measured continuously. The results point out a distinct behavioral pattern of the birds regarding the environment exposition during the experiment. Three probabilistic models of behavior were developed from the recorded data: probabilistic model for the passage use: FP = 1.10 - 0.244 ln(DBT), probabilistic model for the water facility use: FB = 0.398 + 0.00866(DBT), and probabilistic model for the nest use: FN = 2.22 - 0.272 DBT + 0,011 DBT 2 - 0.000144 DBT 3.

Controle de Acesso utilizando Arduino, banco de dados MySQL e LabVIEW

The search for more reliable security systems and information management of these systems is leading to a growing progress in new technologies investments that allow the implementation of equipment with a high level of reliability, but also have an agile and practical operation. This led people to turn increasingly looking for home automation systems, enterprise and industry for the automation and integration of their systems. The identification by radio frequency is very widespread today for ensuring both agility in handling records data, the reliability of their identification systems, which are increasingly advanced and less susceptible to fraud. Attached to this technology, the use of the database is always very important for the storage of information collected, the area where the MySQL platform is widely used. Using the open source Arduino platform for programming and manipulation of RFID module and LabVIEW software for the union of all these technologies and to develop a user-friendly interface, you can create a highly reliable access control and agility places a high turnover of people. This project aims to prove the advantages of using all these technologies working together, thus improving a flawed system effectively safety, cheaper and quicker

Enhancement of optical absorption by modulation of the oxygen flow of TiO2 films deposited by reactive sputtering

Oxygen-deficient TiO2 films with enhanced visible and near-infrared optical absorption have been deposited by reactive sputtering using a planar diode radio frequency magnetron configuration. It is observed that the increase in the absorption coefficient is more effective when the O-2 gas supply is periodically interrupted rather than by a decrease of the partial O-2 gas pressure in the deposition plasma. The optical absorption coefficient at 1.5 eV increases from about 1 x 10(2) cm(-1) to more than 4 x 10(3) cm(-1) as a result of the gas flow discontinuity. A red-shift of similar to 0.24 eV in the optical absorption edge is also observed. High resolution transmission electron microscopy with composition analysis shows that the films present a dense columnar morphology, with estimated mean column width of 40nm. Moreover, the interruptions of the O-2 gas flow do not produce detectable variations in the film composition along its growing direction. X-ray diffraction and micro-Raman experiments indicate the presence of the TiO2 anatase, rutile, and brookite phases. The anatase phase is dominant, with a slight increment of the rutile and brookite phases in films deposited under discontinued O-2 gas flow. The increase of optical absorption in the visible and near-infrared regions has been attributed to a high density of defects in the TiO2 films, which is consistent with density functional theory calculations that place oxygen-related vacancy states in the upper third of the optical bandgap. The electronic structure calculation results, along with the adopted deposition method and experimental data, have been used to propose a mechanism to explain the formation of the observed oxygen-related defects in TiO2 thin films. The observed increase in sub-bandgap absorption and the modeling of the corresponding changes in the electronic structure are potentially useful concerning the optimization of efficiency of the photocatalytic activity and the magnetic doping of TiO2 films. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4724334]

Surface energy increase of oxygen-plasma-treated PET

Prosthetic composite is a widely used biomaterial that satisfies the criteria for application as an organic implant without adverse reactions. Polyethylene therephthalate (PET) fiber-reinforced composites have been used because of the excellent cell adhesion, biodegradability and biocompatibility. The chemical inertness and low surface energy of PET in general are associated with inadequate bonds for polymer reinforcements. It is recognized that the high strength of composites, which results from the interaction between the constituents, is directly related to the interfacial condition or to the interphase. A radio frequency plasma reactor using oxygen was used to treat PET fibers for 5, 20, 30 and 100 s. The treatment conditions were 13.56 MHz, 50 W, 40 Pa and 3.33 x 10(-7) m(3)/s. A Rame-Hart goniometer was used to measure the contact angle and surface energy variation of fibers treated for different times. The experimental results showed contact angle values from 47degrees to 13degrees and surface energies from 6.4 x 10(-6) to 8.3 x 10(-6) J for the range of 5 to 100 s, respectively. These results were confirmed by the average ultimate tensile strength of the PET fiber/polymethylmethacrylate (PMMA) matrix composite tested in tensile mode and by scanning electron microscopy. (C) 2003 Elsevier B.V. All rights reserved.

Thin films generated by plasma immersion ion implantation and deposition of hexamethyldisilazane mixed with nitrogen in different proportions

In this work, it was used a plasma system composed of a cylindrical stainless steel reactor, a radio-frequency (13.56MHz) power source fixed at either 25 W or 70 W, a power source with a negative bias of 10kV and a 100Hz pulse. The system worked at an operational pressure of 80mTorr which consisted of varying concentrations of the monomer HMDSN and gaseous nitrogen in ratios: HMDSN (mTorr)/nitrogen (mTorr) from 70/10 to 20/60 in terms of operational pressure. The structural characterization of the films was done by FTIR spectroscopy. Absorptions were observed between 3500 cm(-1) to 3200 cm(-1), 3000 cm(-1) to 2900 cm(-1), 2500 cm(-1) to 2000 cm(-1), 1500 cm(-1) to 700 cm(-1), corresponding, respectively, to OH radicals, C-H stretching bonds in CH2 and CH3 molecules, C-N bonds, and finally, strain C-H bonds, Si-CH3 and Si-N groups, for both the 70 W and the 25 W. The contact angle for water was approximately 100 degrees and the surface energy is near 25mJ/m(2) which represents a hydrophobic surface, measured by goniometric method. The aging of the film was also analyzed by measuring the contact angle over a period of time. The stabilization was observed after 4 weeks. The refractive index of these materials presents values from 1.73 to 1.65 measured by ultraviolet-visible technique.

Properties of hydrogenated amorphous carbon films deposited by PECVD and modified by SF6 plasma

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)