Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 59
Filtrar
1.
Sensors (Basel) ; 24(9)2024 Apr 26.
Artigo em Inglês | MEDLINE | ID: mdl-38732872

RESUMO

This paper presents an experimental evaluation of a wearable light-emitting diode (LED) transmitter in an optical camera communications (OCC) system. The evaluation is conducted under conditions of controlled user movement during indoor physical exercise, encompassing both mild and intense exercise scenarios. We introduce an image processing algorithm designed to identify a template signal transmitted by the LED and detected within the image. To enhance this process, we utilize the dynamics of controlled exercise-induced motion to limit the tracking process to a smaller region within the image. We demonstrate the feasibility of detecting the transmitting source within the frames, and thus limit the tracking process to a smaller region within the image, achieving an reduction of 87.3% for mild exercise and 79.0% for intense exercise.


Assuntos
Algoritmos , Exercício Físico , Dispositivos Eletrônicos Vestíveis , Humanos , Exercício Físico/fisiologia , Processamento de Imagem Assistida por Computador/métodos , Fotografação/instrumentação , Fotografação/métodos , Atenção à Saúde
2.
Phytopathology ; 114(1): 126-136, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-37531626

RESUMO

Athelia rolfsii, causal agent of "southern blight" disease, is a soilborne fungal pathogen with a wide host range of more than 500 species. This study's objectives were to (i) quantify the effects of two environmental factors, temperature and soil moisture, on germination of A. rolfsii inoculum (sclerotia), which is a critical event for the onset of disease epidemics and (ii) predict the timing of sclerotial germination by applying population-based threshold-type hydrothermal time (HTT) models. We conducted in vitro germination experiments with three isolates of A. rolfsii isolated from peanuts, which were tested at five temperatures (T), ranging from 17 to 40°C, four matric potentials (Ψm) between -0.12 and -1.57 MPa, and two soil types (fine sand and loamy fine sand), using a factorial design. When Ψm was maintained between -0.12 and -0.53 MPa, T from 22 to 34°C was found to be conducive to sclerotial germination (>50%). The HTT models were fitted for a range of T (22 to 34°C) and Ψm (-0.12 to -1.57 MPa) that accounted for 84% or more of variation in the timing of sclerotial germination. The estimated base T ranged between 0 and 4.5°C and the estimated base Ψm between -2.96 and -1.52 MPa. The results suggest that the HTT modeling approach is a suitable means of predicting the timing of A. rolfsii sclerotial germination. This HTT methodology can potentially be tested to fine-tune fungicide application timing and in-season A. rolfsii management strategies. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.


Assuntos
Ascomicetos , Basidiomycota , Germinação , Areia , Doenças das Plantas/microbiologia , Solo
3.
Psychol Res Behav Manag ; 16: 4973-4987, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-38089530

RESUMO

Background: Although the use of technology is a trend, since the COVID-19 pandemic, its use has been exacerbated, especially in educational processes, causing techno-stress among teachers. Purpose: In order to contribute to the lack of validated and adapted instruments in Latin America, this study aimed to analyze the psychometric properties and factorial structure of the Spanish version of the technostress scale in a large sample of Ecuadorian teachers. Methods: A non-probabilistic intentional sample of 2850 teachers (mean age 40 years, SD= 9.65; 65% female) from various schools throughout the Ecuadorian territory was surveyed online using a cross-sectional design. Data analysis included exploratory (EFA) and confirmatory factor analysis (CFA), factorial invariance, assessment of internal consistency, sex differences in technostress scale scores and convergent validity. Results: The EFA yielded a structure of four factors: skepticism, fatigue, anxiety and inefficiency. Through CFA, the hierarchical model that included a general factor and four nested factors had a better fit, and that model remained invariant across sex, age and public and private institutions. Total omega value (ω) was 0.962 for the total scale and hierarchical omega values (ωh) were 0.886 for the general factor, as well as 0.30, 0.22, 0.12 and 0.21 for the respective nested factors (skepticism, fatigue, anxiety and inefficiency). Moreover, the Resources, Experiences, Demands for Information and Communication Technologies (RED/TIC) scores were significantly higher among women, although effect sizes of comparison of those sex differences were very small. Finally, the RED/TIC scores correlated with the Depression, Anxiety and Stress Scale (DASS-21). Conclusion: The RED/TIC scale has adequate psychometric properties in primary and high school teachers, and its use in that population is supported, which provides a valuable tool for the evaluation and detection of technostress in teachers and facilitates the investigation of this multifactorial phenomenon in Latin America.

4.
Microorganisms ; 11(12)2023 Dec 18.
Artigo em Inglês | MEDLINE | ID: mdl-38138146

RESUMO

The introduction of rhizoma peanut (RP Arachis glabrata Benth) into bahiagrass (Paspalum notatum Flüggé) may require time to develop stable plant-soil microbe interactions as the microbial legacy of the previous plant community may be long-lasting. A previous study showed that <2 years of introducing rhizoma peanut into bahiagrass pastures minimally affected soil bacterial diversity and community composition. In this study, we compared the effects of the long-term inclusion of rhizoma peanut (>8 years) into bahiagrass on soil bacterial diversity and community composition against their monocultures at 0 to 15 and 15 to 30 cm soil depths using next-generation sequencing to target bacterial 16S V3-V4 regions. We observed that a well-established RP-bahiagrass mixed stand led to a 36% increase in bacterial alpha diversity compared to the bahiagrass monoculture. There was a shift from a soil bacterial community dominated by Proteobacteria (~26%) reported in other bahiagrass and rhizoma peanut studies to a soil bacterial community dominated by Firmicutes (39%) in our study. The relative abundance of the bacterial genus Crossiella, known for its antimicrobial traits, was enhanced in the presence of RP. Differences in soil bacterial diversity and community composition were substantial between 0 to 15 and 15 to 30 cm soil layers, with N2-fixing bacteria belonging to the phylum Proteobacteria concentrated in 0 to 15 cm. Introducing RP into bahiagrass pastures is a highly sustainable alternative to mineral N fertilizer inputs. Our results provide evidence that this system also promotes greater soil microbial diversity and is associated with unique taxa that require further study to better understand their contributions to healthy pastures.

6.
Microb Ecol ; 86(4): 2703-2715, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-37507489

RESUMO

Soil microorganisms play key roles in soil nutrient transformations and have a notable effect on plant growth and health. Different plant genotypes can shape soil microbial patterns via the secretion of root exudates and volatiles, but it is uncertain how a difference in soil microorganisms induced by crop cultivars will respond to short-term seasonal variations. A field experiment was conducted to assess the changes in soil bacterial communities of seven rhizoma peanut (Arachis glabrata Benth, RP) cultivars across two growing seasons, April (Spring season) and October (Fall season). Soils' bacterial communities were targeted using 16S rRNA gene amplicon sequencing. Bacterial community diversity and taxonomic composition among rhizoma peanut cultivars were significantly affected by seasons, cultivars, and their interactions (p < 0.05). Alpha diversity, as estimated by the OTU richness and Simpson index, was around onefold decrease in October than in April across most of the RP cultivars, while the soils from Arblick and Latitude had around one time higher alpha diversity in both seasons compared with other cultivars. Beta diversity differed significantly in April (R = 0.073, p < 0.01) and October (R = 0.084, p < 0.01) across seven cultivars. Bacterial dominant taxa (at phylum and genus level) were strongly affected by seasons and varied towards more dominant groups that have functional potentials involved in nutrient cycling from April to October. A large shift in water availability induced by season variations in addition to host cultivar's effects can explain the observed patterns in diversity, composition, and co-occurrence of bacterial taxa. Overall, our results demonstrate an overriding effect of short-term seasonal variations on soil bacterial communities associated with different crop cultivars. The findings suggest that season-induced shifts in environmental conditions could exert stronger impacts on soil microorganisms than the finer-scale rhizosphere effect from crop cultivars, and consequently influence largely microbe-mediated soil processes and crop health in agricultural ecosystems.


Assuntos
Arachis , Solo , Estações do Ano , Arachis/microbiologia , Ecossistema , RNA Ribossômico 16S/genética , Bactérias/genética , Microbiologia do Solo
7.
Opt Express ; 31(13): 21493-21506, 2023 Jun 19.
Artigo em Inglês | MEDLINE | ID: mdl-37381247

RESUMO

This paper presents an experimental study of the turbulence impact caused by temperature inhomogeneity and air bubbles on a global shutter-based underwater optical camera communication (UOCC). The effects of these two phenomena on UOCC links are illustrated in terms of the intensity variations and an associated reduction in the average received intensity of the illuminated pixels corresponding to the optical source projection and the dispersion of the projection on the captured images. Additionally, it is shown that the area of illuminated pixels in the temperature-induced turbulence scenario is higher than in the bubbly water case. To analyze the effects of those two phenomena on the optical link performance, the signal-to-noise ratio (SNR) of the system is evaluated by considering different points as the regions of interest (ROI) from the light source projection of the captured images. The results indicate that the system performance is improved by averaging over the value of several pixels produced by the point spread function, compared to simply using the central and the maximum pixel value as the ROIs.

8.
PLoS One ; 18(5): e0285842, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37228054

RESUMO

BACKGROUND: Psychological capital (PsyCap) as a higher-order positive psychological resources (that include hope, efficacy, resilience, and optimism, or the HERO within). This construct was widely described and evaluated in the workplace; however, there is little research in other contexts, such as education, due to the lack of validated and adapted instruments in Latin America. Therefore, the objective of this study is to analyze the psychometric properties and factorial structure of the Spanish version of the psychological capital scale in a large sample of Ecuadorian university students. METHODS: A non-probabilistic convenience sample of 1732 university students (mean age 20 years, SD = 2,29; 55% female) from the city of Loja-Ecuador were surveyed online using a cross-sectional design. RESULTS: The respecified second-order 4-factor model showed the best fit to the data (CMIN/DF = 7.99, CFI = .977, TLI = .970 NFI = .974, IFI = .980, AIC = 443.833, RMSEA = .064 [058, .070]), and such model remained invariant across sex, age and public and private institutions. The internal consistency was adequate, with Alpha and Omega coefficients for the total scale (α = .941, ω = .942) and its four factors: self-efficacy (α = .869, ω = .872), hope (α = .888, ω = .889), resilience (α = .774, ω = .785), and optimism (α = .840, ω = .840). Finally, the PsyCap and its dimensions correlated with academic engagement and satisfaction. CONCLUSIONS: The psychological capital showed adequate psychometric properties in university students, and its use in this context is supported.


Assuntos
Estudantes , Humanos , Feminino , Adulto Jovem , Adulto , Masculino , Equador , Psicometria/métodos , Estudos Transversais , Universidades , Inquéritos e Questionários , Estudantes/psicologia , Reprodutibilidade dos Testes
9.
Opt Express ; 30(24): 43910-43924, 2022 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-36523079

RESUMO

Symmetries in system modeling can be exploited to obtain analytical results on the system behavior and to speed up computations using the symmetric model. This work explores the use of symmetries in radiant surfaces for calculating the induced irradiance distributions by developing a general mathematical expression. The obtained model is applied to flat, cylindrical, and spherical sources to obtain explicit expressions. An experimental evaluation of the flat source is carried out and compared with a traditional point source, and the obtained procedure for the flat scenario is compared with the direct integration approach, which shows an improvement in the computation time of at least two orders of magnitude with a relative root mean square error of less than 10%. The results show that the proposed approach enhances short-range predictions for extended sources. To demonstrate the impact of this in optical wireless communications we have outlined a few applications.

10.
Opt Express ; 30(12): 20261-20277, 2022 Jun 06.
Artigo em Inglês | MEDLINE | ID: mdl-36224776

RESUMO

In rolling shutter (RS)-based optical camera communication (OCC) links, selecting the appropriate camera's exposure time is critical, as it limits the reception bandwidth. In long exposures, the pixels accumulate over time the incoming irradiance of several consecutive symbols. As a result, a harmful intersymbol interference corrupts the received signal. Consequently, reducing the exposure time is required to increase the reception bandwidth at the cost of producing dark images with impracticable light conditions for human or machine-supervised applications. Alternatively, deep learning (DL) equalizers can be trained to mitigate the exposure-related ISI. These equalizers must be trained considering the transmitter clock and the camera's exposure, which can be exceptionally challenging if those parameters are unknown in advance (e.g., if the camera does not reveal its internal settings). In those cases, the receiver must estimate those parameters directly from the images, which are severely distorted by the exposure time. This work proposes a DL estimator for this purpose, which is trained using synthetic images generated for thousands of representative cases. This estimator enables the receiver operation under multiple possible configurations, regardless of the camera used. The results obtained during the validation, using more than 7000 real images, registered relative errors lower than 1% and 2% when estimating the transmitter clock and the exposure time, respectively. The obtained errors guarantee the optimal performance of the following equalization and decoding receiver stages, keeping bit error rates below the forward error correction limit. This estimator is a central component of any OCC receiver that operates over moderate exposure conditions. It decouples the reception routines from the cameras used, ultimately enabling cloud-based receiver architectures.


Assuntos
Aprendizado Profundo , Comunicação , Humanos
11.
Rev. cuba. enferm ; 38(3)sept. 2022.
Artigo em Espanhol | LILACS, BDENF - Enfermagem, CUMED | ID: biblio-1441561

RESUMO

Introducción: El Patient Health Questionnaire es un instrumento breve para evaluar ansiedad y depresión, cuya estructura factorial no es clara. Objetivo: Analizar la confiabilidad, validez convergente, divergente y de constructo como la estructura factorial del Patient Health Questionnaire en universitarios ecuatorianos. Métodos: La muestra fue de 1732 estudiantes, con una edad promedio de 20 años; 55 % fueron mujeres de tres universidades de Loja, Ecuador. Los instrumentos aplicados, en su versión en español fueron: Cuestionario de Aceptación y acción, Cuestionario de Capital Psicológico, Escala de Depresión y Ansiedad, Escala de Estrés percibido. Resultados: La estructura factorial se ajustó mejor al modelo bifactorial (CMIN/DF = 14,247; CFI = 0,996; GFI = 0,996; NFI = 0,996, RMSEA = 0,087). Este modelo es invariante entre hombres y mujeres. La confiabilidad fue óptima para la escala total (α = 0,879; ω = 0,880) y sus dos factores: ansiedad (α = 0,838; ω = 0,838) y depresión α = 0,779; ω = 0,780). Las puntuaciones se correlacionaron con indicadores de salud mental. Conclusiones: El Patient Health Questionnaire es una escala con propiedades psicométricas óptimas para estudiantes universitarios ecuatorianos, que presenta una estructura de dos factores(AU)


Introduction: The Patient Health Questionnaire is a brief instrument for assessing anxiety and depression, whose factorial structure is not clear. Objective: To analyze the reliability, convergent, divergent and construct validity, as well as the factorial structure, of the Patient Health Questionnaire in Ecuadorian university students. Methods: The sample consisted of 1732 students, with an average age of twenty years. 55 % were women from three universities in Loja. The instruments applied were the Acceptance and Action Questionnaire, the Psychological Capital Questionnaire, the Depression and Anxiety Scale, and the Perceived Stress Scale. Results: The factorial structure was better adjusted to the bifactorial model (CMIN/DF=14.247; CFI = 0.996; GFI = 0.996; NFI = 0.996, RMSEA = 0.087). This model is invariant between men and women. Reliability was optimal for the total scale (α = 0.879; ω = 0.880) and its two factors: anxiety (α = 0.838; ω = 0.838) and depression (α = 0.779; ω = 0.780). Scores were correlated with mental health indicators. Conclusions: The Patient Health Questionnaire is a scale with optimal psychometric properties for Ecuadorian university students, presenting a bifactorial structure(AU)


Assuntos
Humanos , Adulto Jovem , Questionário de Saúde do Paciente
12.
Int. j. clin. health psychol. (Internet) ; 22(3): 1-7, Sept. - dec. 2022. ilus, tab
Artigo em Inglês | IBECS | ID: ibc-208426

RESUMO

Background/Objective: Depression represents a leading cause of disability and a major contributor to the overall global burden of disease with women systematically reporting a higher prevalence than men. This study aimed to examine the predictive value and relation of three transdiagnostic psychological factors (perceived stress, psychological inflexibility and loneliness) on depression and its sex differences for the general population in a large sample of Ecuador.Method: A non-probabilistic and non-clinical sample of 16.074 people from across Ecuador were online surveyed using a cross-sectional design. The structural equation model was based on scores from standardized questionnaires as measures of depression, psychological perceived stress, psychological inflexibility, and loneliness.Results: Women reported significantly higher levels of depression, mediated by differences in perceived stress, psychological inflexibility and loneliness. Perceived stress was the most important predictor of depression and mediated the effect of loneliness on depression. Complementarily, psychological inflexibility partially mediated the effect of perceived stress and loneliness on depression. The overall model accounted for the 78% of the total variance in depression.Conclusions: Results of this study provide a novel and robust transdiagnostic model of sex differences on depression and insights on how to design effective programs for preventing depression targeting modifiable transdiagnostic risk factors. (AU)


Assuntos
Humanos , Adulto Jovem , Adulto , Pessoa de Meia-Idade , Idoso , Depressão , Estresse Psicológico , Solidão , Inquéritos e Questionários , Equador
13.
Int J Clin Health Psychol ; 22(3): 100322, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35892040

RESUMO

Background/Objective: Depression represents a leading cause of disability and a major contributor to the overall global burden of disease with women systematically reporting a higher prevalence than men. This study aimed to examine the predictive value and relation of three transdiagnostic psychological factors (perceived stress, psychological inflexibility and loneliness) on depression and its sex differences for the general population in a large sample of Ecuador. Method: A non-probabilistic and non-clinical sample of 16.074 people from across Ecuador were online surveyed using a cross-sectional design. The structural equation model was based on scores from standardized questionnaires as measures of depression, psychological perceived stress, psychological inflexibility, and loneliness. Results: Women reported significantly higher levels of depression, mediated by differences in perceived stress, psychological inflexibility and loneliness. Perceived stress was the most important predictor of depression and mediated the effect of loneliness on depression. Complementarily, psychological inflexibility partially mediated the effect of perceived stress and loneliness on depression. The overall model accounted for the 78% of the total variance in depression. Conclusions: Results of this study provide a novel and robust transdiagnostic model of sex differences on depression and insights on how to design effective programs for preventing depression targeting modifiable transdiagnostic risk factors.

14.
Front Psychol ; 13: 813894, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35572338

RESUMO

Background: The Patient Health Questionnaire-9 (PHQ-9) is the most well-known self-report measure to screen for depressive symptomatology, although discerning which is the factor structure that represents the best fit remains a challenge. Objective: The aim of this study was to analyze the psychometric properties and factorial structure of the Spanish version of the PHQ-9 in a large sample of Ecuadorian college students. Methods: A total of 5,394 students (M = 22.03 years; SD = 3.05; 54.8% female) from three Ecuadorian universities were surveyed using a computerized questionnaire within a 4-week assessment period. The PHQ-9 was tested for factorial structure, reliability, and correlations with other mental health-related measures. Results: The hierarchical model that included a general factor and three nested factors had a better fit, and such a hierarchical structure remained invariant across sex and age. Total omega value (ω) was 0.90 for the total scale and hierarchical omega values (ωh) were 0.68 for the general factor, as well as 0.34, 0.38, and 0.44 for the respective nested factors (somatic, cognitive/affective, concentration/motor). Moreover, PHQ-9 scores were significantly higher among women, although effect sizes of comparison of those sex differences were very small. Finally, the PHQ-9 scores correlated with multiple mental health indicators (psychological inflexibility, loneliness, stress, and satisfaction with life). Discussion: The Spanish version of the PHQ-9 showed good psychometric properties among Ecuadorian college students. The hierarchical structure showed the best fit for the data, including not only a dominant general factor, but also the somatic, cognitive/affective and concentration/motor subcomponents. In conclusion, the PHQ-9 tool seems to represent an easy-to-implement screening questionnaire to design preventive programs for those Ecuadorian college students at risk of developing depressive disorders.

15.
Opt Lett ; 47(5): 1053-1056, 2022 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-35230288

RESUMO

Optical camera communication (OCC) is a promising technology to be used in future wireless communication systems. In this work, a cluster-based data detection procedure is applied to enhance the performance of an OCC system. A multispectral camera is employed to capture the spectral variations in light-emitting diodes (LEDs) caused by temperature. This strategy's system performance is compared with a system that uses traditional linear methods, such as zero-forcing (ZF) and minimum mean square error (MMSE) equalizers. The findings of this study indicate that an improvement in the bit error rate (BER) can be achieved by applying a clustering approach.

16.
J Environ Qual ; 51(1): 55-65, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34978336

RESUMO

Incorporating legumes is one option for improving pasture fertility, sustainability, and biodiversity. Diazotrophic microorganisms, including rhizobia that form symbioses with legumes, represent a small fraction of the total soil microbial community. Yet, they can offset nitrogen (N) fertilizer inputs through their ability to convert atmospheric N2 into plant-usable N via biological N2 fixation (BNF). This study used amplicon sequencing of 16S rRNA genes to investigate soil bacterial community composition and diversity in grazed 'Argentine' bahiagrass (Paspalum notatum Flügge) pastures where N fertilizer was supplanted with legume-derived N from BNF in some treatments. Treatments consisted of bahiagrass fertilized with (a) mineral N (224 kg N ha-1  yr-1 ), (b) combination mineral N (34 kg N ha-1  yr-1 ) and legume-derived N via cool-season clover (CSC) (Trifolium spp.) mix, or (c) combination mineral N (34 kg N ha-1  yr-1 ) and legume-derived N via CSC mix and strips of Ecoturf rhizoma peanut (Arachis glabrata Benth.). Bradyrhizobium spp. relative abundance was 44% greater in the mixed pasture. Other bacterial genera with BNF or denitrification potentials were greater in pastures with legumes, whereas sequences assigned to genera associated with high litter turnover were greater in bahiagrass pastures receiving only mineral N. Soil bacteria alpha diversity was greater in pastures receiving 34 kg ha-1  yr-1 N fertilizer application and the CSC mix than in pastures with the CSC mix and rhizoma peanut strips. Our results demonstrate soil microbial community shifts that may affect soil C and N cycling in pastures common to the southeastern United States.


Assuntos
Arachis , Solo , Bactérias/genética , Florida , RNA Ribossômico 16S/genética
17.
Opt Express ; 29(15): 22973-22991, 2021 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-34614574

RESUMO

In rolling shutter-based optical camera communication (OCC), the camera's exposure time limits the achievable reception bandwidth. In long-exposure settings, the image sensor pixels average the incident received power, producing inter-symbol interference (ISI), which is perceived in the images as a spatial mixture of the symbol bands. Hence, the shortest possible exposure configuration should be selected to alleviate ISI. However, in these conditions, the camera produces dark images with impracticable light conditions for human or machine-supervised applications. In this paper, a novel convolutional autoencoder-based equalizer is proposed to alleviate exposure-related ISI and noise. Furthermore, unlike other systems that use artificial neural networks for equalization and decoding, the training procedure is conducted offline using synthetic images for which no prior information about the deployment scenario is used. Hence the training can be performed for a wide range of cameras and signal-to-noise ratio (SNR) conditions, using a vast number of samples, improving the network fitting and the system decoding robustness. The results obtained in the experimental validation record the highest ISI mitigation potential for Manchester encoded on-off keying signals. The system can mitigate the ISI produced by exposure time windows that are up to seven times longer than the transmission symbol duration, with bit error rates (BER) lower than 10-5 under optimal SNR conditions. Consequently, the reception bandwidth improves up to 14 times compared to non-equalized systems. In addition, under harsh SNRs conditions, the system achieves BERs below the forward error correction limit for 1dB and 5 dB while operating with exposure times that are 2 and 4 times greater than the symbol time, respectively.

18.
Sensors (Basel) ; 21(18)2021 Sep 19.
Artigo em Inglês | MEDLINE | ID: mdl-34577489

RESUMO

In this paper, we explore the potential applications of Optical Wireless Communications in the tourism industry, considering both indoor and outdoor scenarios and different transmission speeds. They range from high-speed atmospheric outdoor links (Free-Space Optics (FSO)) to indoor systems based on high-speed lighting networks (known under the trade name LiFi©) or low-speed services support the Internet of Things networks, using visible light (VLC) or IR emitters, with receivers based on either on classical photodiodes or in image sensors, known as Optical Camera Communications. The avant-garde applications of this technology have been studied focusing on three possible use scenarios: the traveler himself, in what we have called TAN (Tourist Area Network); the tourist facility, which includes not only the hotel but also leisure areas (theme parks, museums, natural protected areas) or services (restaurants, shopping areas, etc.); and the entire destination, which can be both the city or the territory where the tourist is received, within the paradigm of the Smart Tourist Destination (STD). In addition to the classic services based on radio frequency and wired broadband networks, these technologies will make it possible to meet the tourist's challenging needs, the establishment, and the destination. Besides, they cover the services imposed by the new marketing services related to location or context and feed the big data systems used to study tourist behavior.


Assuntos
Aplicações da Informática Médica , Turismo , Indústrias , Rede Social , Tecnologia sem Fio
19.
Sensors (Basel) ; 21(8)2021 Apr 13.
Artigo em Inglês | MEDLINE | ID: mdl-33924508

RESUMO

Optical wireless communications in outdoor scenarios are challenged by uncontrollable atmospheric conditions that impair the channel quality. In this paper, different optical camera communications (OCC) equipment are experimentally studied in the laboratory and the field, and a sub-pixel architecture is raised as a potential solution for outdoor wireless sensor networks (WSN) applications, considering its achievable data throughput, the spatial division of sources, and the ability of cameras to overcome the attenuation caused by different atmospheric conditions such as rain, turbulence and the presence of aerosols. Sub-pixel OCC shows particularly adequate capabilities for some of the WSN applications presented, also in terms of cost-effectiveness and scalability. The novel topology of sub-pixel projection of multiple transmitters over the receiver using small optical devices is presented as a solution using OCC that re-uses camera equipment for communication purposes on top of video-monitoring.

20.
Sensors (Basel) ; 21(9)2021 Apr 22.
Artigo em Inglês | MEDLINE | ID: mdl-33921995

RESUMO

Visible light communications (VLC) technology is emerging as a candidate to meet the demand for interconnected devices' communications. However, the costs of incorporating specific hardware into end-user devices slow down its market entry. Optical camera communication (OCC) technology paves the way by reusing cameras as receivers. These systems have generally been evaluated under static conditions, in which transmitting sources are recognized using computationally expensive discovery algorithms. In vehicle-to-vehicle networks and wearable devices, tracking algorithms, as proposed in this work, allow one to reduce the time required to locate a moving source and hence the latency of these systems, increasing the data rate by up to 2100%. The proposed receiver architecture combines discovery and tracking algorithms that analyze spatial features of a custom RGB LED transmitter matrix, highlighted in the scene by varying the cameras' exposure time. By using an anchor LED and changing the intensity of the green LED, the receiver can track the light source with a slow temporal deterioration. Moreover, data bits sent over the red and blue channels do not significantly affect detection, hence transmission occurs uninterrupted. Finally, a novel experimental methodology to evaluate the evolution of the detection's performance is proposed. With the analysis of the mean and standard deviation of novel K parameters, it is possible to evaluate the detected region-of-interest scale and centrality against the transmitter source's ideal location.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...