The aim of this paper was to study three variables in hydrogen peroxide bleaching of cotton fabrics： the amount of hydrogen peroxide （H2O2）, peroxide stabilizer （Na2SiO3） and the process temperature. The factoria...
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The aim of this paper was to study three variables in hydrogen peroxide bleaching of cotton fabrics： the amount of hydrogen peroxide （H2O2）, peroxide stabilizer （Na2SiO3） and the process temperature. The factorial planning of two levels and three factors was done in order to obtain an optimized recipe for subsequent comparison with commons recipes used in industry. Were evaluated the brightness （DL）, energy consumption （dQ）, H2O2 residual （Rox）, processing time and ecological costs.
The use of diffusers around the horizontal-axis wind turbines has been widely studied since the diffuser improves the power coefficient of the turbine and it is often called DAWTs （diffuser augmented wind turbines）....
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The use of diffusers around the horizontal-axis wind turbines has been widely studied since the diffuser improves the power coefficient of the turbine and it is often called DAWTs （diffuser augmented wind turbines）.Turbines using diffuser are called DWATs （Diffuser Augmented Turbines）,and have efficiency bigger than the Betz limit （maximum energy flow extracted = 59.26%）. Thus, this study presents a mathematical model describing the behavior of the velocity profile internally to a diffuser according to the characteristics of flow and geometry of a conical diffuser. The results are compared with experimental data and show good agreement.
This paper presents a T-slot planar inverted F antenna (PIFA) for wireless mobile communications GSM/UMTS/WCDMA systems. A modified ground plane is used to increase the bandwidth. A prototype is implemented and the di...
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ISBN:
(纸本)9781479913961
This paper presents a T-slot planar inverted F antenna (PIFA) for wireless mobile communications GSM/UMTS/WCDMA systems. A modified ground plane is used to increase the bandwidth. A prototype is implemented and the differences in performance of the antenna with and without the presence of the mobile handset and the user's head are estimated. The simulations are performed using the finite difference time domain (FDTD) method.
This paper presents a parallel implementation approach of selective harmonic compensator for active power filters. This approach uses field programmable gate array (FPGAs) in order to reduce the compensator computatio...
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ISBN:
(纸本)9781467324120
This paper presents a parallel implementation approach of selective harmonic compensator for active power filters. This approach uses field programmable gate array (FPGAs) in order to reduce the compensator computational time. To compensate for even a small number of harmonics digital filters require multiple calculation instructions involving multiplications and additions. Thus, to improve the performance of the computer system it is proposed the digital compensator implementation using parallel structures in FPGA devices. Experimental results are presented to compare the speedup of the proposed parallel approach with the DSP sequential execution time conventionally used in active power filters applications.
The amorphous Cu46Zr42Al7Y5 alloy presents large supercooled liquid region (ΔTX = 100 K), with a viscosity of about 106 N.s/m2 where the material can flow as a liquid, making it possible an easy deformation in this t...
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The amorphous Cu46Zr42Al7Y5 alloy presents large supercooled liquid region (ΔTX = 100 K), with a viscosity of about 106 N.s/m2 where the material can flow as a liquid, making it possible an easy deformation in this temperature region. The aim of this work was to analyze processing routes to produce bulks of metallic glasses. Two kinds of materials were used: amorphous powders and ribbons, both were consolidated by hot extrusion in temperatures inside the range between Tg and Tx, with a ram speed of 1 mm/min and extrusion ratio of 3 : 1. Analysis of X-Ray Diffratometry (XRD), Differential Scanning Calorimetry (DSC) and Scanning Electron Microscopy (SEM), revealed that the proposed consolidation routes were effective to produce large bulks of amorphous materials, even with the strong decreasing of ΔTX observed after deformation by milling and during extrusion.
This paper presents the description of a DC electronic load based on an interleaved chopper converter to determine the biasing and dynamics characteristics of either fuel cells (FCs) and photovoltaic panels (PVs). Var...
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This paper presents the description of a DC electronic load based on an interleaved chopper converter to determine the biasing and dynamics characteristics of either fuel cells (FCs) and photovoltaic panels (PVs). Variable loads are used for experimental data acquisition of I-V power supply characteristics in a way that several operating points can be easily obtained. Laboratory load current tests using ordinary power resistors are not an easy solution due to their size, cost and overall weight. To resolve that it is proposed in this paper that the current through electronically varying loads can give better resolution to the I-V characteristics of FC and PV sources. The interleaved operation of the chopper converter ensures an input high frequency current ripple, reducing so the input LC filters size and converter volume. The converter transfer function is analyzed and controllers are designed to obtain a fast dynamic response and insure good stability in steady state operation. It is presented the converter operating principles, operating states and design. The simulated and results are compared to each other in order to prove the electronic load effectiveness in acquiring the I-V biasing curves of fuel cells and photovoltaic panels.
This work evaluated thermal comfort conditions in an operating room ventilated with spiral diffuser jet. The objective is to asses conditions of local thermal discomfort of the patient and the surgical team in this ki...
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ISBN:
(纸本)9781627480758
This work evaluated thermal comfort conditions in an operating room ventilated with spiral diffuser jet. The objective is to asses conditions of local thermal discomfort of the patient and the surgical team in this kind of environment using the concept of equivalent temperatures and a manikin with heated sensors. The results showed a very small change in the equivalent temperatures in different parts of the body for the surgeon, the nurse and the patient, It occurs due to the air distribution system with spiral diffuser jet that provides more homogeneous conditions of heat exchange. However, there were higher equivalent temperatures on the head of the surgeon and the nurse and on the patient's chest, because of the heat exchange by radiation with the surgical focus.
In this work some theoretical aspects of constitutive equations for thixotropic fluids and restrictions on their functional forms are formally discussed. In the current study a formal emphasis has been given to the st...
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In this work some theoretical aspects of constitutive equations for thixotropic fluids and restrictions on their functional forms are formally discussed. In the current study a formal emphasis has been given to the structural nature of this substances. The behavior of thixotropic fluids is analyzed in terms of simple isothermal laminar shear flow.
This paper presents a connection system based on static converters aiming to connect three phase generators of mini and micro hydropower plants to the distribution single-phase rural electric utilities in Brazil. It w...
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This paper presents a connection system based on static converters aiming to connect three phase generators of mini and micro hydropower plants to the distribution single-phase rural electric utilities in Brazil. It will be presented the modeling of static converters and the computational simulation results obtained by PSIM software.
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