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using spatial » using spectral (Expander búsqueda)
1
artículo
Publicado 2012
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This paper reviews the different indices used to describe and characterize the horizontal structure or spatial pattern in forest stands, with particular emphasis on those which have been applied to the study of tropical forests. These indices have been classified according to their data-inventory requirements. A number of aspects concerned with the statistical properties of the most commonly employed indices (Fisher and Morisita indices, LQV techniques and SADIE in the quadrats group; Clark-Evans, Pielou and Byth-Ripley in the nearest-neighbour group; The empirical L(d) and O-ring functions in the mapped data group) and their applicability to tropical stands, have been tested in experimental plots located in an Andean tropical forest.
2
artículo
Publicado 2021
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The backscatter coefficient (BSC) quantifies the frequency-dependent reflectivity of tissues. Accurate estimation of the BSC is only possible with the knowledge of the attenuation coefficient slope (ACS) of the tissues under examination. In this study, the use of attenuation maps constructed using full angular spatial compounding (FASC) is proposed for attenuation compensation when imaging integrated BSCs. Experimental validation of the proposed approach was obtained using two cylindrical physical phantoms with off-centered inclusions having different ACS and BSC values than the background, and in a phantom containing an ex vivo chicken breast sample embedded in an agar matrix. With the phantom data, three different ACS maps were employed for attenuation compensation: (1) a ground truth ACS map constructed using insertion loss techniques, (2) the estimated ACS map using FASC attenuation ...
3
artículo
Publicado 2022
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Climate change, as well as the appearance of pests and diseases, are affecting olive plantations (Olea europaea L.) and the production of olives in the world, therefore, there is an urgent need for tools to help us identify the spatial and temporal evolution of the olive groves, regarding the attack of pests, in this case, the Orthezia olivicola and the olive borer Phloeotribus scarabaeoides. In this work, we use information from freely available satellite images that allowed us to carry out spatial and temporal analysis and the combination of vegetation indices. For the studied area, according to the values of the NDVI (Normalized Difference Vegetation Index), it was identified that the surface of diseased plants ranges from 42% to 68%, moderately healthy plants from 2% to 18%, and the state of the plantation considered as very healthy plants with a tendency to zero, which means that pr...
4
artículo
Publicado 2017
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Immediately north of Salta city, several streams have their sources on the eastern slopes of the Sierra de Vaqueros, whose piedemonte is urbanized. The man influence on the mountain environment makes it necessary to estimate erosion rates the location of their different erosion classes and their analysis. The work was carried out with satellite images, generating the base map and thematic maps of the Vaqueros and Los Nogales microbasins, through the use of a Geographic Information System (GIS); this allowed to characterize the study areas and to obtain the necessary information to apply the Universal Equation of Soil Loss (USLE). R, K and LS factors were obtained through adaptations of the method, due to the unavailability of data established by authors. The average of current water erosion showed a rate of 47 t/ha/year for the Vaqueros microbasin and 45 t/ha/year for the microbasin Los ...
5
artículo
Publicado 2018
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Attenuation imaging using spectral techniques such as the spectral log difference (SLD) method suffers from a severe trade-off between spatial resolution and estimation variance. Recently, the regularized spectral log difference (RSLD) method was proposed as a technique that extends such trade-off by incorporating spatial priors (i.e., total variation) in the inversion process. However, the reduction of the variance of attenuation images could also be accomplished by post-processing of the attenuation maps using noise reduction techniques. The main goal of this study is to determine which strategy (i.e., noise handling during or after the attenuation image reconstruction) provides attenuation maps of better quality, both with synthetic data and experimental data obtained from calibrated physical phantoms. The results suggest that the noise rejection mechanism of RSLD significantly outper...
6
artículo
Publicado 2021
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This article describes the fundamentals of digital image digital processing using a free-access, web user interface called Octave-Online. This interface is part of the GNU operating system software applications, as well as it is known as the equivalent of Matlab in free versión; for this reason, this tool was chosen in order to give a practical approach to the use of ten basic techniques of spatial processing of digital images. To do this, we started by collecting 8 files with image contents in JPG and with different characteristics such as high and low contrast, high and low frequency, shades of gray, and intensity of colors, to put the proposed processing techniques into practice. Subsequently, some guidelines were provided for access, upload of JPG files, creation of * .m extension files, and knowledge of certain tools offered by the Octave-Online web user in...
7
artículo
Publicado 2025
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Due to its complex topography, the Lake Titicaca region, located in the southern tropical Andes, presents great challenges for atmospheric modeling. This study aims to improve the representation of precipitation and air surface temperature using the Weather Research and Forecasting (WRF) model at high spatial resolution (2 km), during the austral summer of 2020. We conducted 11 experiments with different configurations of topography, land use, physical parameterizations, and lake surface temperature (LST). Each experiment was evaluated considering in-situ data from the Peruvian-Bolivian region and gridded precipitation products. For precipitation, the best configuration, with an average bias close to zero mm, includes using the GMTED2010 topography (not smoothed) and the land use data of Eva et al. (2004), along with the Purdue Lin microphysics and the Grell 3D cumulus scheme. For air te...
8
artículo
Publicado 2025
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Purpose Avocado production in Peru takes place in different biomes and under different agricultural systems (e.g., conventional, organic, or agroforestry). Therefore, it is important to understand differences in the environmental profile of avocado production within the diversity of these cultivation systems. Hence, the main objective of the study was to conduct a cradle-togate attributional Life Cycle Assessment of avocado production in Peru by small and medium-sized producers, under multiple scenarios to provide insights for enhancing environmental performance and including a sensitivity and uncertainty analysis. Methods Primary data were collected from 80 small and medium-sized producers (i.e., 355 ha) for the year 2023 to build the life cycle inventory, which was supported by the ecoinvent database. SimaPro was used to integrate inventory flows and assessment methods. The latter incl...
9
artículo
Publicado 2013
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Determination of the stereochemistry of organic compounds has been a problem that the scientific community has been giving solution to over the years. Different methods have emerged, such as X-ray Diffraction or different types of Nuclear Magnetic Resonance (NMR). However, it just has been discovered that the method used in the determination of the absolute configuration of the α-acids derived from hops used in the manufacture of bitter beers, was not the appropriate.
10
artículo
Publicado 2013
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Determination of the stereochemistry of organic compounds has been a problem that the scientific community has been giving solution to over the years. Different methods have emerged, such as X-ray Diffraction or different types of Nuclear Magnetic Resonance (NMR). However, it just has been discovered that the method used in the determination of the absolute configuration of the ?-acids derived from hops used in the manufacture of bitter beers, was not the appropriate.
11
artículo
The objective of this research was to determine the difference in spatial orientation in four-year-old children of a Public Educational Institution and a Private Educational Institution, Lima. The theoretical foundations were based on the theory of Jean Piaget, which refers to the cognitive processes developed according to the age of the infants, which are related to the stages of space acquisition. In addition, Howard Gardner's theory of spatial intelligence was considered. The research is basic type, comparative descriptive level. A checklist was used as an instrument. 0.023 (p <.005) was obtained, that is, there is a difference in spatial orientation in four years in favor of the private educational institution.
12
artículo
Publicado 2021
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This research studies exploratorily the relationship between socio-spatial segregation in the spread of the COVID-19 disease and its lethality in the city of Lima. The consequences of the COVID-19 pandemic have revealed the inconsistencies of an uncontrolled urban growth in different Peruvian cities as well as inequalities within them, boosting the devastating effects of the pandemic, what placed Peru at the top of the list of the countries with the highest lethality in the world from COVID -19. In this regard, it is considered the urban-socio spatial segregation as the spread and amplifying cause of the COVID-19, especially in popular sectors. Methodologically, the research is based on the exploratory method using a mixed methodology bibliographic review, field observation and quantitative data to approach the effects of the pandemic and the unequal impact in Lima city.
13
artículo
Publicado 2024
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This study analyzed spatial soil fertility variability in a 1440 m² plot in Mosquera, Colombia, to create homogeneous management zones for precision agriculture. 480 soil samples were collected using a 3x1 m grid, analyzing pH, electrical conductivity, phosphorus, exchangeable cations, microelements, and soil organic matter (SOM). Principal Component Analysis (PCA) identified SOM, pH, and electrical conductivity as key indicators for zoning. Kriging interpolation mapped these properties, revealing high variability. The exponential model best represented the semivariograms. Fuzzy clustering, based on indicator thresholds, divided the plot into two zones, with high overlap between pH and SOM-based divisions. A QUEFTS model simulated crop yield, showing that optimized N and K fertilization, based on zoning, maximized yields. The study demonstrates the effectiv...
14
documento de trabajo
Publicado 2024
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Quality and safety of the soil are essential to ensure social and economic development and provides the supply of contaminant free food. With agriculture intensification, expansion of urban zones, construction of roads, and mining, some agricultural soils sites become polluted increasing environmental risks to ecosystems functions and human health. Hence the need know the spatial distribution of elements in soils, we mapped 25 elements, namely Ca, Mg, Sr, Ba, Be, K, Na, As, Sb, Se, Tl, Cd, Zn, Al, Pb, Hg, Cr, Ni, Cu, Mo, Ag, Fe, Co, Mn and V, using various geospatial datasets, such as remote sensing, climate, topography, soil data, and distance, to establish the spatial estimation models of spatial distribution trained trough machine learning model with a supervised dataset of 109 topsoil samples, into Google earth engine platform. Using R2, RMSE and MAE to assess the prediction accuracy...
15
documento de trabajo
Publicado 2024
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Quality and safety of the soil are essential to ensure social and economic development and provides the supply of contaminant free food. With agriculture intensification, expansion of urban zones, construction of roads, and mining, some agricultural soils sites become polluted increasing environmental risks to ecosystems functions and human health. Hence the need know the spatial distribution of elements in soils, we mapped 25 elements, namely Ca, Mg, Sr, Ba, Be, K, Na, As, Sb, Se, Tl, Cd, Zn, Al, Pb, Hg, Cr, Ni, Cu, Mo, Ag, Fe, Co, Mn and V, using various geospatial datasets, such as remote sensing, climate, topography, soil data, and distance, to establish the spatial estimation models of spatial distribution trained trough machine learning model with a supervised dataset of 109 topsoil samples, into Google earth engine platform. Using R2, RMSE and MAE to assess the prediction accuracy...
16
artículo
Publicado 2024
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The architecture, engineering, construction, and operation (AECO) industry has brought transformations within the field. Despite the changes, traditional teaching methods such as analyzing two-dimensional plans and models are still being used in training processes, which do not effectively promote the development of spatial skills. In this context, augmented reality (AR) can be used as a tool to translate two-dimensional information into three-dimensional space. Thus, the present study explores the use of the VT-Platform AR tool to develop and reinforce spatial skills among undergraduate civil engineering students. The study follows a quantita-tive approach with a descriptive scope and an experimental design. Students in the sanitary engineering subject were divided into two groups: an experimental group and a control group. A short-term teaching-learning methodology was proposed for the...
17
artículo
Publicado 2024
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The risks of environmental pollution occupy a relevant place in the scheme of ecological studies at the national and territorial level. These must be treated with the articulation of a system of preventive measures and proactive solutions that contribute to mitigate the consequences of the negative deterioration on the existing ecosystems. The objective of this research was to evaluate the environmental impact of the solid particles dispersed in the air resulting from the fires that occurred in the Municipal Landfill of the city of Santa Clara, in Villa Clara, Cuba, on the community of Caracatey, due to its proximity to the landfill and the spatial reach that these particles had in the city of Santa Clara. For the development of this research, methods of information collection and methods of processing the information collected were used, among which the following stand out: participator...
18
tesis de grado
Publicado 2022
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In the high mountain ecosystems of the Huaytapallana Regional Conservation Area (ACR-H) there are three species of flora (Krapfia macropetala, Gentianella scarlatinostriata and Senecio canescens) of social, economic, cultural and medicinal importance, however their population status and undefined local distribution make these species area more vulnerable to extinction. Therefore, the objective of this work is to determine the population distribution for repopulation purpose in the ACR-H from the potential distribution in Peru using Maxent algorithm and a local model developed with the Saaty pairwise hierarchy matrix, adding a soil sample for a better application of the final model. The results show that the Species Distribution Models (SDMs) have a high confidence because the Area Under the Curve (AUC) surpass 0.90. Otherwise, the local model is consistent by showing a Consistency Ratio ...
19
artículo
Publicado 2017
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Malaria has steadily increased in the Peruvian Amazon over the last five years. This study aimed to determine the parasite prevalence and micro-geographical heterogeneity of Plasmodium vivax parasitaemia in communities of the Peruvian Amazon. Four cross-sectional active case detection surveys were conducted between May and July 2015 in four riverine communities in Mazan district. Analysis of 2785 samples of 820 individuals nested within 154 households for Plasmodium parasitaemia was carried out using light microscopy and qPCR. The spatio-temporal distribution of Plasmodium parasitaemia, dominated by P. vivax, was shown to cluster at both household and community levels. Of enrolled individuals, 47% had at least one P. vivax parasitaemia and 10% P. falciparum, by qPCR, both of which were predominantly sub-microscopic and asymptomatic. Spatial analysis detected significant clustering in thr...
20
tesis de maestría
Publicado 2017
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The attenuation coefficient slope (ACS) has the potential to be used for tissue characterization and as a diagnostic ultrasound tool, hence complementing B-mode images. The ACS can be valuable for estimation of other ultrasound parameters such as the backscatter coefficient. There is a well-known tradeoff between the precision of the estimated ACS values and the data block size used in spectral-based techniques such as the spectral log difference (SLD). This trade-off limits the practical usefulness of spectral-based attenuation imaging techniques. In this thesis work, the regularized spectral log difference (RSLD) technique is presented in detail and evaluated with simulations and experiments with physical phantoms, ex vivo and in vivo. The ACS values obtained when using the RSLD technique were compared to the ones obtained when using the SLD technique, as well as the ground truth ACS v...
