Francisco Araujo - Academia.edu (original) (raw)
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Papers by Francisco Araujo
Environmental Management, 2003
The biodiversity of many Brazilian rivers is seriously threatened by industrial and municipal pol... more The biodiversity of many Brazilian rivers is seriously threatened by industrial and municipal pollution, and Rio Paraiba do Sul, located between two major industrial centers is one example of this situation. A survey of the fish assemblage was conducted from October 1998 to September 1999 and the data were used to develop an index of biotic integrity (IBI). We sampled three zones in bracketing a large urban–industrial complex to evaluate water quality changes and the usefulness of the IBI as a monitoring tool. Water quality was classified as poor upstream of the effluent discharges, very poor near the discharges, and poor–fair downstream of the discharges, with this latter situation revealing the current biological capacity of the river. Physical and chemical habitat characteristics were also measured at each site to construct an independent environmental index to validate the IBI. The habitat and IBI indices were highly correlated, suggesting this IBI would be applicable to other large rivers in southeast Brazil.
Optics Letters, 2006
A new concept to measure rotation angles based on a fiber-optic modal Mach-Zehnder interferometer... more A new concept to measure rotation angles based on a fiber-optic modal Mach-Zehnder interferometer is demonstrated by using a nonadiabatic taper cascaded with a long-period fiber grating. Information about the magnitude of the rotation angle can be obtained from the measurement of the interference pattern visibility, and under certain conditions it is also possible to obtain the sign of the rotation angle from the induced phase variation in the fiber interferometer.
Fiber and Integrated Optics, 2005
Measurement Science & Technology, 2005
Optical Engineering, 2004
IEEE Photonics Technology Letters, 2001
Laser & Photonics Reviews, 2008
A review of optical fiber sensing demonstrations based on photonic crystal fibers is presented. T... more A review of optical fiber sensing demonstrations based on photonic crystal fibers is presented. The text is organized in five main sections: the first three deal with sensing approaches relying on fiber Bragg gratings, long-period gratings and interferometric structures; the fourth one reports applications of these fibers for gas and liquid sensing; finally, the last section focuses on the exploitation of nonlinear effects in photonic crystal fibers for sensing.
IEEE Photonics Technology Letters, 1999
Optical Engineering, 2000
ABSTRACT
Optics Letters, 2006
A new concept to measure rotation angles based on a fiber-optic modal Mach-Zehnder interferometer... more A new concept to measure rotation angles based on a fiber-optic modal Mach-Zehnder interferometer is demonstrated by using a nonadiabatic taper cascaded with a long-period fiber grating. Information about the magnitude of the rotation angle can be obtained from the measurement of the interference pattern visibility, and under certain conditions it is also possible to obtain the sign of the rotation angle from the induced phase variation in the fiber interferometer.
Fiber and Integrated Optics, 2005
Measurement Science & Technology, 2005
Optical Engineering, 2004
IEEE Photonics Technology Letters, 2001
Laser & Photonics Reviews, 2008
A review of optical fiber sensing demonstrations based on photonic crystal fibers is presented. T... more A review of optical fiber sensing demonstrations based on photonic crystal fibers is presented. The text is organized in five main sections: the first three deal with sensing approaches relying on fiber Bragg gratings, long-period gratings and interferometric structures; the fourth one reports applications of these fibers for gas and liquid sensing; finally, the last section focuses on the exploitation of nonlinear effects in photonic crystal fibers for sensing.
Environmental Management, 2003
The biodiversity of many Brazilian rivers is seriously threatened by industrial and municipal pol... more The biodiversity of many Brazilian rivers is seriously threatened by industrial and municipal pollution, and Rio Paraiba do Sul, located between two major industrial centers is one example of this situation. A survey of the fish assemblage was conducted from October 1998 to September 1999 and the data were used to develop an index of biotic integrity (IBI). We sampled three zones in bracketing a large urban–industrial complex to evaluate water quality changes and the usefulness of the IBI as a monitoring tool. Water quality was classified as poor upstream of the effluent discharges, very poor near the discharges, and poor–fair downstream of the discharges, with this latter situation revealing the current biological capacity of the river. Physical and chemical habitat characteristics were also measured at each site to construct an independent environmental index to validate the IBI. The habitat and IBI indices were highly correlated, suggesting this IBI would be applicable to other large rivers in southeast Brazil.
Optics Letters, 2006
A new concept to measure rotation angles based on a fiber-optic modal Mach-Zehnder interferometer... more A new concept to measure rotation angles based on a fiber-optic modal Mach-Zehnder interferometer is demonstrated by using a nonadiabatic taper cascaded with a long-period fiber grating. Information about the magnitude of the rotation angle can be obtained from the measurement of the interference pattern visibility, and under certain conditions it is also possible to obtain the sign of the rotation angle from the induced phase variation in the fiber interferometer.
Fiber and Integrated Optics, 2005
Measurement Science & Technology, 2005
Optical Engineering, 2004
IEEE Photonics Technology Letters, 2001
Laser & Photonics Reviews, 2008
A review of optical fiber sensing demonstrations based on photonic crystal fibers is presented. T... more A review of optical fiber sensing demonstrations based on photonic crystal fibers is presented. The text is organized in five main sections: the first three deal with sensing approaches relying on fiber Bragg gratings, long-period gratings and interferometric structures; the fourth one reports applications of these fibers for gas and liquid sensing; finally, the last section focuses on the exploitation of nonlinear effects in photonic crystal fibers for sensing.
IEEE Photonics Technology Letters, 1999
Optical Engineering, 2000
ABSTRACT
Optics Letters, 2006
A new concept to measure rotation angles based on a fiber-optic modal Mach-Zehnder interferometer... more A new concept to measure rotation angles based on a fiber-optic modal Mach-Zehnder interferometer is demonstrated by using a nonadiabatic taper cascaded with a long-period fiber grating. Information about the magnitude of the rotation angle can be obtained from the measurement of the interference pattern visibility, and under certain conditions it is also possible to obtain the sign of the rotation angle from the induced phase variation in the fiber interferometer.
Fiber and Integrated Optics, 2005
Measurement Science & Technology, 2005
Optical Engineering, 2004
IEEE Photonics Technology Letters, 2001
Laser & Photonics Reviews, 2008
A review of optical fiber sensing demonstrations based on photonic crystal fibers is presented. T... more A review of optical fiber sensing demonstrations based on photonic crystal fibers is presented. The text is organized in five main sections: the first three deal with sensing approaches relying on fiber Bragg gratings, long-period gratings and interferometric structures; the fourth one reports applications of these fibers for gas and liquid sensing; finally, the last section focuses on the exploitation of nonlinear effects in photonic crystal fibers for sensing.