The Experts below are selected from a list of 5037 Experts worldwide ranked by ideXlab platform
Jean Claude Ruel - One of the best experts on this subject based on the ideXlab platform.
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windthrow in riparian buffer Strips effect of wind exposure thinning and Strip Width
Forest Ecology and Management, 2001Co-Authors: Jean Claude Ruel, Kevin R CooperAbstract:This paper discusses the effects of topography, riparian buffer Strip Width and thinning on the amount of windthrow over 9 years in balsam fir (Abies balsamea) stands. Monitoring of windthrow was conducted in 25 riparian areas representing five treatments: uncut control, thinned 20 m Strip, unthinned 20, 40 and 60 m Strips. Wind tunnel measurements were made on a topographical model of the study area to provide an estimate of local wind behaviour. A cluster analysis performed on the wind speed data led to the identification of four major topographic units of similar wind behaviour. Wind speed in valleys varied greatly depending upon the direction of the approaching winds and the presence of small topographic features. When the wind blows perpendicularly to the valley, wind speed tends to be lower but more variable than when it blows parallel to the valley. Windthrow was not related to Strip Width or thinning. The field study showed that windthrow 5 years after cutting was found to be correlated with the speed of winds blowing roughly perpendicular to the Strips. Windthrow after 7 and 9 years, following an unusual wind event that occurred between years 5 and 7, was no longer correlated with this wind direction. High levels of damage were observed where the valley widened, offering less shelter to the buffer Strips.
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Windthrow in riparian buffer Strips: Effect of wind exposure, thinning and Strip Width
Forest Ecology and Management, 2001Co-Authors: Jean Claude Ruel, Daniel Pin, Kevin CooperAbstract:This paper discusses the effects of topography, riparian buffer Strip Width and thinning on the amount of windthrow over 9 years in balsam fir (Abies balsamea) stands. Monitoring of windthrow was conducted in 25 riparian areas representing five treatments: uncut control, thinned 20 m Strip, unthinned 20, 40 and 60 m Strips. Wind tunnel measurements were made on a topographical model of the study area to provide an estimate of local wind behaviour. A cluster analysis performed on the wind speed data led to the identification of four major topographic units of similar wind behaviour. Wind speed in valleys varied greatly depending upon the direction of the approaching winds and the presence of small topographic features. When the wind blows perpendicularly to the valley, wind speed tends to be lower but more variable than when it blows parallel to the valley. Windthrow was not related to Strip Width or thinning. The field is study showed that windthrow 5 years after cutting was found to be correlated with the speed of winds blowing roughly perpendicular to the Strips. Windthrow after 7 and 9 years, following an unusual wind event that occurred between years 5 and 7, was no longer correlated with this wind direction. High levels of damage were observed where the valley widened, offering less shelter to the buffer Strips. © 2001 Elsevier Science B.V.
Kevin R Cooper - One of the best experts on this subject based on the ideXlab platform.
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windthrow in riparian buffer Strips effect of wind exposure thinning and Strip Width
Forest Ecology and Management, 2001Co-Authors: Jean Claude Ruel, Kevin R CooperAbstract:This paper discusses the effects of topography, riparian buffer Strip Width and thinning on the amount of windthrow over 9 years in balsam fir (Abies balsamea) stands. Monitoring of windthrow was conducted in 25 riparian areas representing five treatments: uncut control, thinned 20 m Strip, unthinned 20, 40 and 60 m Strips. Wind tunnel measurements were made on a topographical model of the study area to provide an estimate of local wind behaviour. A cluster analysis performed on the wind speed data led to the identification of four major topographic units of similar wind behaviour. Wind speed in valleys varied greatly depending upon the direction of the approaching winds and the presence of small topographic features. When the wind blows perpendicularly to the valley, wind speed tends to be lower but more variable than when it blows parallel to the valley. Windthrow was not related to Strip Width or thinning. The field study showed that windthrow 5 years after cutting was found to be correlated with the speed of winds blowing roughly perpendicular to the Strips. Windthrow after 7 and 9 years, following an unusual wind event that occurred between years 5 and 7, was no longer correlated with this wind direction. High levels of damage were observed where the valley widened, offering less shelter to the buffer Strips.
Kevin Cooper - One of the best experts on this subject based on the ideXlab platform.
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Windthrow in riparian buffer Strips: Effect of wind exposure, thinning and Strip Width
Forest Ecology and Management, 2001Co-Authors: Jean Claude Ruel, Daniel Pin, Kevin CooperAbstract:This paper discusses the effects of topography, riparian buffer Strip Width and thinning on the amount of windthrow over 9 years in balsam fir (Abies balsamea) stands. Monitoring of windthrow was conducted in 25 riparian areas representing five treatments: uncut control, thinned 20 m Strip, unthinned 20, 40 and 60 m Strips. Wind tunnel measurements were made on a topographical model of the study area to provide an estimate of local wind behaviour. A cluster analysis performed on the wind speed data led to the identification of four major topographic units of similar wind behaviour. Wind speed in valleys varied greatly depending upon the direction of the approaching winds and the presence of small topographic features. When the wind blows perpendicularly to the valley, wind speed tends to be lower but more variable than when it blows parallel to the valley. Windthrow was not related to Strip Width or thinning. The field is study showed that windthrow 5 years after cutting was found to be correlated with the speed of winds blowing roughly perpendicular to the Strips. Windthrow after 7 and 9 years, following an unusual wind event that occurred between years 5 and 7, was no longer correlated with this wind direction. High levels of damage were observed where the valley widened, offering less shelter to the buffer Strips. © 2001 Elsevier Science B.V.
Yahya Rahmat-samii - One of the best experts on this subject based on the ideXlab platform.
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Experimental and Numerical Analysis to Determine the Equivalent Strip Width for Cylindrical Wire for Mesh Reflector Antennas
2006 IEEE Antennas and Propagation Society International Symposium, 2006Co-Authors: Harish Rajagopalan, Yahya Rahmat-samiiAbstract:Reflector antennas are used to realize large deployable antennas in many satellite and ground antenna systems. The utilization of a knitted wire mesh as the reflecting surface provides reduced wind effects, unfurlability and deployable capability. In the past, the mesh surface problem has been solved by using wire-grid modeling, Strip-aperture modeling and periodic method of moments. In 1982, Butler showed that the equivalent Strip Width of an isolated single conducting wire is twice its diameter. This result was based on the equivalency of the total currents induced on the conducting cylinder and the narrow Strip. This Strip-wire equivalence has been used in all the Strip aperture and wire grid formulations. This equivalence has not been verified in practice for mesh reflector structures where one may also consider the interaction among adjacent wires. The motivation of this work is to calculate the equivalent factor (beta) (beta = w (Width of the Strip) / d (diameter of the wire)) thus determining the equivalent Strip Width for a cylindrical wire with measurement and numerical analysis for mesh reflectors by considering the interaction among adjacent wires
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Equivalent Strip Width for cylindrical wire for mesh reflector antennas: Experiments, waveguide, and plane-wave simulations
IEEE Transactions on Antennas and Propagation, 2006Co-Authors: Harish Rajagopalan, Amane Miura, Yahya Rahmat-samiiAbstract:This paper presents the verification of the equivalent Strip Width for a cylindrical wire for mesh reflector antennas with experimental and numerical analysis and compares waveguide and plane-wave simulations. For experimental purposes, the transmission and reflection characteristics of copper Strips and copper wires were measured. For numerical analysis, a model of the experimental setup was designed and simulated in High-Frequency Structure Simulator (HFSS). Comparing the measurement and HFSS simulated results confirmed that the numerical model was accurate. Using HFSS, it was verified that the equivalent Strip Width for a cylindrical wire is almost twice (~1.89) the wire diameter (for an infinitely thin Strip) for typical mesh reflector structures. A periodic Strip model was simulated both in HFSS and periodic Method of Moments (MoM) using the plane-wave incidence at different angles and the transmission and reflection characteristics were determined. The effects of the thickness of the Strip, angle of incidence, and the spacing between the adjacent Strips on the equivalence between the Strip Width and wire diameter were also studied. As the center to center Strip spacing increases beyond 1.5lambda, the equivalent factor beta (Strip Width /wire diameter) approaches the classical factor of 2
Shahram Amirmoradi - One of the best experts on this subject based on the ideXlab platform.
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determination of optimal Strip Width in Strip intercropping of maize zea mays l and bean phaseolus vulgaris l in northeast iran
Journal of Cleaner Production, 2015Co-Authors: Mehdi Nassiri Mahallati, Alireza Koocheki, F Mondani, Hassan Feizi, Shahram AmirmoradiAbstract:Abstract Intercropping is a sustainable method for crop production used to maximize utilization of available resources. The aim of this study, conducted in 2009 and 2010, was to determine an optimal Strip Width in maize/bean Strip intercropping. Treatments evaluated in the study were contribution of different Strip Width and intercrops of 2 rows bean and 2 rows maize (II), 3 rows bean and 3 rows maize (III), 4 rows bean and 4 rows maize (IV), 5 rows bean and 5 rows maize (V), maize and bean monocultures. The higher than average temperature in 2010, led to decrease crop yields in that year. The climatic conditions had more effect on reduction of bean yield than maize. Radiation absorption, radiation use efficiency, biological yield, land equivalent ratio, crowding coefficient and system productivity index were greater in 2009 than in 2010. Radiation use efficiency for maize and bean were higher in 2009 than 2010 (8.9% and 17.6% respectively). The Strip intercropping system enhanced radiation absorption, radiation use efficiency, biological yield, land equivalent ratio, crowding coefficient and system productivity index compared with the monoculture system. Increasing Strip Width from 2 to 5 rows resulted in a decrease all the criteria measured. The best Strip Width was with II and III Strip intercropping treatments. Although biological yield in intercropping was less than in monoculture, total land productivity was improved by greater land equivalent ratio (1.39 and 1.37). This means that 39% and 37% more land was required for monoculture than intercropping to produce the same yields in 2009 and 2010, respectively. Therefore it was demonstrated that an intercropping system is more effective than a monoculture system in resource utilization. It also appears that equivalent row numbers of 3 and 4 for each crop in a Strip manner is more promising in resource use than other combination of rows.
