The scattering of electromagnetic waves from strong drift turbulent vortex streets in uniform pla... more The scattering of electromagnetic waves from strong drift turbulent vortex streets in uniform plasmas has been considered. An integral equation describing the scattering is obtained in a Fourier representation. This integral equation is then solved approximately by the Galerkin method using two trial functions. Assuming arbitrary polarization and a plane wave for the incident electromagnetic field, a compact expression for
The objective of this work is to quantify the accuracy and precision of particle sizing performed... more The objective of this work is to quantify the accuracy and precision of particle sizing performed through light scattering goniometry. A rigorous characterization of this simple method depends on a complete description of the scattering geometry, and to our knowledge this has not yet been done. We have determined the central diameter (d0) and standard deviation (sigma) of samples of
The cork oak tree (Quercus suber L.) symbolizes the Montado landscape in Portugal and is a centra... more The cork oak tree (Quercus suber L.) symbolizes the Montado landscape in Portugal and is a central element in the country’s social and economic history. In recent decades, the loss of thousands of cork oaks has been reported, revealing the ongoing decline of these agroforestry ecosystems. This emblematic tree of the Mediterranean Basin is host to the soil-born root pathogen Phytophthora cinnamomi, an active cork oak decline driver. In this framework, the early diagnosis of trees infected by the oomycete by non-invasive methods should contribute to the sustainable management of cork oak ecosystems, which motivated this work. Gas exchange and visible/near-infrared (400–1100 nm) reflectance spectroscopy measurements were conducted on leaves of both control and P. cinnamomi inoculated plants. These measurements were taken at 63, 78, 91, 126, and 248 days after inoculation. Additionally, at the end of the experiment, biochemical assays of pigments, sugars, and starch were performed. The ...
Kiwifruit consumption has increased due to its rich nutritional properties. Although ‘Hayward’ co... more Kiwifruit consumption has increased due to its rich nutritional properties. Although ‘Hayward’ continues to be the main cultivar, others, such as yellow fleshed ‘Jintao’, are of increasing interest. The objective of this research was to evaluate the acceptability and storage performance of these two cultivars. Sensory evaluation of green ‘Hayward’ and yellow ‘Jintao’ kiwifruit were performed along cold storage for three seasons/years to follow the organoleptic characteristics through ripening, as well as the acquisition of their spectra by Vis-NIR. For ‘Jintao’ were performed two sensory evaluations per year at 2.5- and 4.5-months’ storage and for ‘Hayward’ at 2.5-, 4.5- and 5.5-months’ storage. The nonparametric Mann–Whitney test and Kruskal–Wallis ANOVA were performed to test the significant differences between the mean ranks among the storage time. A non-metric multidimensional scaling plot method using the ALSCAL algorithm in a seven-point Likert scale was applied to determine t...
Cork oak tree (Quercus suber L.) symbolises Montado landscape in Portugal and is a central elemen... more Cork oak tree (Quercus suber L.) symbolises Montado landscape in Portugal and is a central element in the country's social and economic history. In recent decades, the loss of thousands of cork oaks has been reported, revealing the ongoing decline of these agro-forestry ecosystems. This emblematic tree of the Mediterranean Basin is host to the soil-born root pathogen Phytophthora cinnamomi, an active cork oak decline driver. In this framework, the early diagnosis of trees infected by the oomycete by non-invasive methods should contribute to the sustainable management of cork oak ecosystems and motivated this work. Using leaf reflectance spectroscopy it was possible to distinguish plants inoculated with P. cinnamomi from non-inoculated plants in a long course assay and to argue about the factors contributing to this differentiation. Spectral acquisitions in the visible-near infrared (400–1100 nm) were performed at 63, 78, 91, 126 and 248 days after inoculation (DAI), on the abaxi...
An ultra-low-cost RCL meter, aimed at IoT applications, was developed, and was used to measure el... more An ultra-low-cost RCL meter, aimed at IoT applications, was developed, and was used to measure electrical components based on standard techniques without the need of additional electronics beyond the AVR® micro-controller hardware itself and high-level routines. The models and pseudo-routines required to measure admittance parameters are described, and a benchmark between the ATmega328P and ATmega32U4 AVR® micro-controllers was performed to validate the resistance and capacitance measurements. Both ATmega328P and ATmega32U4 micro-controllers could measure isolated resistances from 0.5 Ω to 80 MΩ and capacitances from 100 fF to 4.7 mF. Inductance measurements are estimated at between 0.2 mH to 1.5 H. The accuracy and range of the measurements of series and parallel RC networks are demonstrated. The relative accuracy (ar) and relative precision (pr) of the measurements were quantified. For the resistance measurements, typically ar, pr < 10% in the interval 100 Ω–100 MΩ. For the cap...
Algarve Citrus comprise many species, hybrids and varieties, which are only harvested at their op... more Algarve Citrus comprise many species, hybrids and varieties, which are only harvested at their optimal edible ripening stage. As protected geographical indication (PGI) commodities, these fruits must observe several quantitative and qualitative requirements stipulated in a specific norm. In respect to oranges [Citrus sinensis (L.) Osbeck], the norm comprises a general approach for the whole group, without addressing specifically the various existing varieties. The main objectives of this study were: 1) to test if the consumer evaluation fully agreed with the Algarve Citrus norm and/or with other quality parameters measured; 2) if there were any differences among major orange varieties that should be accounted by the Algarve Citrus norm. Then, we compared ‘Newhall’, ‘Lane late’ and ‘Valencia late’ from orchards located in Quarteira and Paderne, at the beginning of the respective marketing season, concerning both these parameters and their sensorial evaluation by a semi-trained panel....
The scattering of electromagnetic waves from strong drift turbulent vortex streets in uniform pla... more The scattering of electromagnetic waves from strong drift turbulent vortex streets in uniform plasmas has been considered. An integral equation describing the scattering is obtained in a Fourier representation. This integral equation is then solved approximately by the Galerkin method using two trial functions. Assuming arbitrary polarization and a plane wave for the incident electromagnetic field, a compact expression for
The objective of this work is to quantify the accuracy and precision of particle sizing performed... more The objective of this work is to quantify the accuracy and precision of particle sizing performed through light scattering goniometry. A rigorous characterization of this simple method depends on a complete description of the scattering geometry, and to our knowledge this has not yet been done. We have determined the central diameter (d0) and standard deviation (sigma) of samples of
The cork oak tree (Quercus suber L.) symbolizes the Montado landscape in Portugal and is a centra... more The cork oak tree (Quercus suber L.) symbolizes the Montado landscape in Portugal and is a central element in the country’s social and economic history. In recent decades, the loss of thousands of cork oaks has been reported, revealing the ongoing decline of these agroforestry ecosystems. This emblematic tree of the Mediterranean Basin is host to the soil-born root pathogen Phytophthora cinnamomi, an active cork oak decline driver. In this framework, the early diagnosis of trees infected by the oomycete by non-invasive methods should contribute to the sustainable management of cork oak ecosystems, which motivated this work. Gas exchange and visible/near-infrared (400–1100 nm) reflectance spectroscopy measurements were conducted on leaves of both control and P. cinnamomi inoculated plants. These measurements were taken at 63, 78, 91, 126, and 248 days after inoculation. Additionally, at the end of the experiment, biochemical assays of pigments, sugars, and starch were performed. The ...
Kiwifruit consumption has increased due to its rich nutritional properties. Although ‘Hayward’ co... more Kiwifruit consumption has increased due to its rich nutritional properties. Although ‘Hayward’ continues to be the main cultivar, others, such as yellow fleshed ‘Jintao’, are of increasing interest. The objective of this research was to evaluate the acceptability and storage performance of these two cultivars. Sensory evaluation of green ‘Hayward’ and yellow ‘Jintao’ kiwifruit were performed along cold storage for three seasons/years to follow the organoleptic characteristics through ripening, as well as the acquisition of their spectra by Vis-NIR. For ‘Jintao’ were performed two sensory evaluations per year at 2.5- and 4.5-months’ storage and for ‘Hayward’ at 2.5-, 4.5- and 5.5-months’ storage. The nonparametric Mann–Whitney test and Kruskal–Wallis ANOVA were performed to test the significant differences between the mean ranks among the storage time. A non-metric multidimensional scaling plot method using the ALSCAL algorithm in a seven-point Likert scale was applied to determine t...
Cork oak tree (Quercus suber L.) symbolises Montado landscape in Portugal and is a central elemen... more Cork oak tree (Quercus suber L.) symbolises Montado landscape in Portugal and is a central element in the country's social and economic history. In recent decades, the loss of thousands of cork oaks has been reported, revealing the ongoing decline of these agro-forestry ecosystems. This emblematic tree of the Mediterranean Basin is host to the soil-born root pathogen Phytophthora cinnamomi, an active cork oak decline driver. In this framework, the early diagnosis of trees infected by the oomycete by non-invasive methods should contribute to the sustainable management of cork oak ecosystems and motivated this work. Using leaf reflectance spectroscopy it was possible to distinguish plants inoculated with P. cinnamomi from non-inoculated plants in a long course assay and to argue about the factors contributing to this differentiation. Spectral acquisitions in the visible-near infrared (400–1100 nm) were performed at 63, 78, 91, 126 and 248 days after inoculation (DAI), on the abaxi...
An ultra-low-cost RCL meter, aimed at IoT applications, was developed, and was used to measure el... more An ultra-low-cost RCL meter, aimed at IoT applications, was developed, and was used to measure electrical components based on standard techniques without the need of additional electronics beyond the AVR® micro-controller hardware itself and high-level routines. The models and pseudo-routines required to measure admittance parameters are described, and a benchmark between the ATmega328P and ATmega32U4 AVR® micro-controllers was performed to validate the resistance and capacitance measurements. Both ATmega328P and ATmega32U4 micro-controllers could measure isolated resistances from 0.5 Ω to 80 MΩ and capacitances from 100 fF to 4.7 mF. Inductance measurements are estimated at between 0.2 mH to 1.5 H. The accuracy and range of the measurements of series and parallel RC networks are demonstrated. The relative accuracy (ar) and relative precision (pr) of the measurements were quantified. For the resistance measurements, typically ar, pr < 10% in the interval 100 Ω–100 MΩ. For the cap...
Algarve Citrus comprise many species, hybrids and varieties, which are only harvested at their op... more Algarve Citrus comprise many species, hybrids and varieties, which are only harvested at their optimal edible ripening stage. As protected geographical indication (PGI) commodities, these fruits must observe several quantitative and qualitative requirements stipulated in a specific norm. In respect to oranges [Citrus sinensis (L.) Osbeck], the norm comprises a general approach for the whole group, without addressing specifically the various existing varieties. The main objectives of this study were: 1) to test if the consumer evaluation fully agreed with the Algarve Citrus norm and/or with other quality parameters measured; 2) if there were any differences among major orange varieties that should be accounted by the Algarve Citrus norm. Then, we compared ‘Newhall’, ‘Lane late’ and ‘Valencia late’ from orchards located in Quarteira and Paderne, at the beginning of the respective marketing season, concerning both these parameters and their sensorial evaluation by a semi-trained panel....
Uploads
Papers by Rui Guerra