The Experts below are selected from a list of 232308 Experts worldwide ranked by ideXlab platform
Armando J D Silvestre - One of the best experts on this subject based on the ideXlab platform.
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strategies to reduce the Brightness reversion of industrial ecf bleached eucalyptus globulus kraft pulp
Journal of Chemical Technology & Biotechnology, 2008Co-Authors: Isabel M C L Seco, Carlos Pascoal Neto, Armando J D SilvestreAbstract:BACKGROUND: Brightness stability is a key property of bleached chemical pulps and is primarily determined by wood species and bleaching process conditions. Eucalyptus globulus is becoming a very important raw material for hardwood pulp production. In spite of this importance, there is a relative lack of systematic studies in the literature dealing with the subject. This research aims to study the effect of some of the foremost bleaching parameters of a DEDD bleaching sequence as well as the effect of a final P stage (DEDP instead of DEDD) in the Brightness stability of bleached E. globulus kraft pulps. RESULTS: The increase of the D0 stage temperature from 55 °C to 90 °C caused an increase in Brightness stability. Increasing the ClO2 charges from 2.8% to 3.2% also improved significantly the Brightness stability. A high H2SO4 charge in the D0 stage (10 kg tonne−1 pulp) diminished the Brightness stability. The combination of H2O2 addition to the E stage and ClO2 reduction in the two final D stages does not affect Brightness reversion. Raising the D2 stage temperature from 65 °C to 82 °C decreased the Brightness reversion, while an increase was obtained when the temperature rose above 82 °C. Substitution of the last ClO2 stage in the DEDD sequence by a H2O2 stage (DEDP) significantly reduced the Brightness reversion. CONCLUSION: For an existing pulp mill in which the implementation of new technologies to improve Brightness reversion is considered, the results obtained showed that Brightness stability can be improved without any significant capital investment. Copyright © 2007 Society of Chemical Industry
Isabel M C L Seco - One of the best experts on this subject based on the ideXlab platform.
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strategies to reduce the Brightness reversion of industrial ecf bleached eucalyptus globulus kraft pulp
Journal of Chemical Technology & Biotechnology, 2008Co-Authors: Isabel M C L Seco, Carlos Pascoal Neto, Armando J D SilvestreAbstract:BACKGROUND: Brightness stability is a key property of bleached chemical pulps and is primarily determined by wood species and bleaching process conditions. Eucalyptus globulus is becoming a very important raw material for hardwood pulp production. In spite of this importance, there is a relative lack of systematic studies in the literature dealing with the subject. This research aims to study the effect of some of the foremost bleaching parameters of a DEDD bleaching sequence as well as the effect of a final P stage (DEDP instead of DEDD) in the Brightness stability of bleached E. globulus kraft pulps. RESULTS: The increase of the D0 stage temperature from 55 °C to 90 °C caused an increase in Brightness stability. Increasing the ClO2 charges from 2.8% to 3.2% also improved significantly the Brightness stability. A high H2SO4 charge in the D0 stage (10 kg tonne−1 pulp) diminished the Brightness stability. The combination of H2O2 addition to the E stage and ClO2 reduction in the two final D stages does not affect Brightness reversion. Raising the D2 stage temperature from 65 °C to 82 °C decreased the Brightness reversion, while an increase was obtained when the temperature rose above 82 °C. Substitution of the last ClO2 stage in the DEDD sequence by a H2O2 stage (DEDP) significantly reduced the Brightness reversion. CONCLUSION: For an existing pulp mill in which the implementation of new technologies to improve Brightness reversion is considered, the results obtained showed that Brightness stability can be improved without any significant capital investment. Copyright © 2007 Society of Chemical Industry
Muhammad Tahir - One of the best experts on this subject based on the ideXlab platform.
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joint rate Brightness control using variable rate mppm for led based visible light communication systems
IEEE Transactions on Wireless Communications, 2013Co-Authors: Abu Bakar Siddique, Muhammad TahirAbstract:LED based lighting systems provide an opportunity for data transmission in addition to their traditional use as source of illumination. Brightness control is required to achieve either desired level of illumination or to achieve energy conservation. Conventionally, simultaneous data transmission as well as Brightness control is achieved using two different modulation schemes. Either pulse width modulation or pulse amplitude modulation is used for Brightness control and some variants of pulse position modulation are employed for data transmission. The need for two different modulation schemes, to meet the dual objective, makes the system design complex. In this paper we propose variable-rate multi-pulse-position-modulation (VR-MPPM), for LED based visible light communication system, to achieve joint Brightness control and data transmission. The proposed approach eradicates the need for either pulse width modulation or pulse amplitude modulation and still achieves the Brightness control. Encoder and decoder algorithms for VR-MPPM realization are developed and are implemented on the hardware testbed. Experimental results revealing the effect of Brightness level variation on symbol error rate are also provided. Existence of an underlying trade-off between achievable resolution for Brightness control and the corresponding successful data transmission rate is recognized. To exploit this trade-off, an optimization problem is formulated.
Carlos Pascoal Neto - One of the best experts on this subject based on the ideXlab platform.
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strategies to reduce the Brightness reversion of industrial ecf bleached eucalyptus globulus kraft pulp
Journal of Chemical Technology & Biotechnology, 2008Co-Authors: Isabel M C L Seco, Carlos Pascoal Neto, Armando J D SilvestreAbstract:BACKGROUND: Brightness stability is a key property of bleached chemical pulps and is primarily determined by wood species and bleaching process conditions. Eucalyptus globulus is becoming a very important raw material for hardwood pulp production. In spite of this importance, there is a relative lack of systematic studies in the literature dealing with the subject. This research aims to study the effect of some of the foremost bleaching parameters of a DEDD bleaching sequence as well as the effect of a final P stage (DEDP instead of DEDD) in the Brightness stability of bleached E. globulus kraft pulps. RESULTS: The increase of the D0 stage temperature from 55 °C to 90 °C caused an increase in Brightness stability. Increasing the ClO2 charges from 2.8% to 3.2% also improved significantly the Brightness stability. A high H2SO4 charge in the D0 stage (10 kg tonne−1 pulp) diminished the Brightness stability. The combination of H2O2 addition to the E stage and ClO2 reduction in the two final D stages does not affect Brightness reversion. Raising the D2 stage temperature from 65 °C to 82 °C decreased the Brightness reversion, while an increase was obtained when the temperature rose above 82 °C. Substitution of the last ClO2 stage in the DEDD sequence by a H2O2 stage (DEDP) significantly reduced the Brightness reversion. CONCLUSION: For an existing pulp mill in which the implementation of new technologies to improve Brightness reversion is considered, the results obtained showed that Brightness stability can be improved without any significant capital investment. Copyright © 2007 Society of Chemical Industry
Bradley Holder - One of the best experts on this subject based on the ideXlab platform.
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optical night sky Brightness measurements from the stratosphere
The Astronomical Journal, 2020Co-Authors: Ajay Gill, Steven J Benton, Anthony M Brown, Paul C Clark, Christopher J Damaren, T F Eifler, A A Fraisse, M Galloway, John W Hartley, Bradley HolderAbstract:This paper presents optical night sky Brightness measurements from the stratosphere using CCD images taken with the Super-pressure Balloon-borne Imaging Telescope (SuperBIT). The data used for estimating the backgrounds were obtained during three commissioning flights in 2016, 2018, and 2019 at altitudes ranging from 28 km to 34 km above sea level. For a valid comparison of the Brightness measurements from the stratosphere with measurements from mountain-top ground-based observatories (taken at zenith on the darkest moonless night at high Galactic and high ecliptic latitudes), the stratospheric Brightness levels were zodiacal light and diffuse Galactic light subtracted, and the airglow Brightness was projected to zenith. The stratospheric Brightness was measured around 5.5 hours, 3 hours, and 2 hours before the local sunrise time in 2016, 2018, and 2019 respectively. The $B$, $V$, $R$, and $I$ Brightness levels in 2016 were 2.7, 1.0, 1.1, and 0.6 mag arcsec$^{-2}$ darker than the darkest ground-based measurements. The $B$, $V$, and $R$ Brightness levels in 2018 were 1.3, 1.0, and 1.3 mag arcsec$^{-2}$ darker than the darkest ground-based measurements. The $U$ and $I$ Brightness levels in 2019 were 0.1 mag arcsec$^{-2}$ brighter than the darkest ground-based measurements, whereas the $B$ and $V$ Brightness levels were 0.8 and 0.6 mag arcsec$^{-2}$ darker than the darkest ground-based measurements. The lower sky Brightness levels, stable photometry, and lower atmospheric absorption make stratospheric observations from a balloon-borne platform a unique tool for astronomy. We plan to continue this work in a future mid-latitude long duration balloon flight with SuperBIT.
