640 research outputs found
Identifying Advantages and Disadvantages of Variable Rate Irrigation – An Updated Review
Variable rate irrigation (VRI) sprinklers on mechanical move irrigation systems (center pivot or lateral move) have been commercially available since 2004. Although the number of VRI, zone or individual sprinkler, systems adopted to date is lower than expected there is a continued interest to harness this technology, especially when climate variability, regulatory nutrient management, water conservation policies, and declining water for agriculture compound the challenges involved for irrigated crop production. This article reviews the potential advantages and potential disadvantages of VRI technology for moving sprinklers, provides updated examples on such aspects, suggests a protocol for designing and implementing VRI technology and reports on the recent advancements. The advantages of VRI technology are demonstrated in the areas of agronomic improvement, greater economic returns, environmental protection and risk management, while the main drawbacks to VRI technology include the complexity to successfully implement the technology and the lack of evidence that it assures better performance in net profit or water savings. Although advances have been made in VRI technologies, its penetration into the market will continue to depend on tangible and perceived benefits by producers
Análisis Comparativo Del Posicionamiento GNSS Utilizando Receptor De Bajo Costo U-Blox De Doble Frecuencia Para Aplicaciones Topógrafo-Geodésicas
Se evaluó y comparó estadísticamente el posicionamiento obtenido a través del receptor de bajo costo U-blox ZED-F9P de nueva generación con un receptor geodésico, realizando observaciones GNSS sobre un vértice geodésico mediante del método de Posicionamiento Puntual Preciso y relativo estático, con una distancia de 33 km a la estación de referencia. Esto, con la finalidad de probar la factibilidad de utilizar receptores de bajo costo de gama similares en trabajos topográficos-geodésicos. Para ello, se consideran cuatro escenarios; en el primer escenario, se aplicó la técnica relativo estático con el equipo de bajo costo, en el segundo escenario se procesó con un receptor geodésico en modo relativo estático; ambos mediante un software comercial. Para el tercer y cuarto escenario, se procesó modo Posicionamiento Puntual Preciso con el software RTKLIB. Los resultados muestran que para la técnica Posicionamiento Puntal Preciso la precisión lograda de 1 cm por el equipo de bajo costo es apta para realizar trabajos geodésicos. En el método relativo estático, la precisión lograda de 7 mm indica que es posible utilizar el equipo de bajo costo para trabajos topógrafos-geodésicos de alta precisión considerando una línea base ≤33 km, esto, según la normatividad del Instituto Nacional de Estadística y Geografía.
The new generation, low-cost U-blox ZED-F9P receiver was evaluated and statistically compared by GNSS observations on a geodesic monument, through both Precise Point Positioning and Static relative positioning techniques with a distance of 33 km from the references station. This was done with the purpose of checking the use feasibility of the low-cost receiver of similar gamma in topographic-geodesic works. To that end, four scenarios were considered: in the first scenario, the static relative positioning with the low-cost equipment was applied; in the second scenario, the static relative positioning with a geodetic receiver was applied. Both scenarios were processed with commercial software. The third and fourth scenarios were processed with Precise Point Positioning techniques through the RTKLIB software. The results show that Precise Point Positioning techniques get a precision of 1 cm through the use of low-cost equipment which is suitable to apply in geodetic works. In the static relative method, the precision obtained is 7 mm, indicating the possibility of using the low-cost equipment in both survey and geodetic high precision works, considering a line base ≤30 Km, according to the Instituto Nacional de Estadística y Geografía normative
A split-based incremental deterministic automata minimization algorithm
The final publication is available at Springer via http://dx.doi.org/10.1007/s00224-014-9588-y.
La fecha de publicación corresponde a la versión First OnlineWe here study previous results due to Hopcroft and Almeida et al. to
propose an incremental split-based deterministic automata minimization algorithm
whose average running-time does not depend on the size of the alphabet. The experimentation
carried out shows that our proposal outperforms the algorithms studied
whenever the automata have more than a (quite small) number of states and symbols.García Gómez, P.; Vázquez-De-Parga Andrade, M.; Velasco, JA.; López Rodríguez, D. (2014). A split-based incremental deterministic automata minimization algorithm. Theory of Computing Systems. 1-18. doi:10.1007/s00224-014-9588-y118Hopcroft, J.E., Ullman, J.D.: Introduction to Automata Theory, Languages and Computation. Addison-Wesley Publishing Company (1979)Watson, B.W., Daciuk, J.: An efficient incremental DFA minimization algorithm. Nat. Lang. Eng. 9(1), 49–64 (2003)Almeida, M., Moreira, N., Reis, R.: Incremental DFA minimisation. In: Domaratzki, M., Salomaa, K. (eds.) CIAA, of Lecture Notes in Computer Science, vol. 6482, pp 39–48. Springer (2010)Hopcroft, J.E.: An n ⋅ log n algorithm for minimizing states in a finite automaton. Technical report, Stanford, University, Stanford (1971)Moore, E.F.: Gedanken experiments on sequential machines. In: Shannon, C.E., Mc-Carthy, J. (eds.) Automata Studies. Princeton Universty Press, Princeton (1956)Berstel, J., Boasson, L., Carton, O., Fagnot, I.: Automata: from Mathematics to Applications, chapter Minimization of automata. European Mathematical Society. (arXiv: 1010.5318v3. ) To appear.David, J.: Average complexity of Moore’s and Hopcroft’s algorithms. Theor. Comput. Sci. 417, 50–65 (2012)Almeida, M., Moreira, N., Reis, R.: Aspects of enumeration and generation with a string automata representation. In: Leung, H., Pighizzini, G. (eds.) DCFS, pp 58–69. New Mexico State University, Las Cruces (2006)Gries, D.: Describing an algorithm by Hopcroft. Acta Informatica 2, 97–109 (1973)Aho, A., Hopcroft, J.E., Ullman, J.D.: The Design and Analysis of Computer Algorithms. Addison-Wesley Publishing Company (1974)Blum, N.: A O ( n log n ) implementation of the standard method for minimizing n-state finite automata. Inf. Process. Lett. 57, 65–69 (1996)Knuutila, T.: Re-describing an algorithm by Hopcroft. Theor. Comput. Sci. 250, 333–363 (2001)Veanes, M.: Minimization of symbolic automata. Technical report, Microsoft Research, MSR-TR-2013-48 (2013)Lothaire, M.: Applied Combinatorics on Words chap. 1. Cambridge University Press, Cambridge (2005
Late presentation of chronic HBV and HCV patients seeking first time specialist care in Spain: a 2-year registry review
Chronic viral hepatitis infection affects an estimated 325 million people globally. People who initiate treatment after significant disease progression face increased risk of severe liver complications and death. Data are scarce on the characteristics and risk factors of people who present late to care in Spain and globally. Data were collected from January 2018 to December 2019 to report late presentation (LP) to specialist care at 11 large university hospitals in Spain to assess related risk factors using a multivariable logistic regression model. 2290 (CHB = 505, CHC = 1785) patients were analysed, with 581 (25.2%) presenting late. Hepatitis C patients more frequently reported LP compared to hepatitis B patients (28.1% vs 15.0%; p < 0.001). Older age (p < 0.001), being male
(p < 0.001), being Spanish‑born (p < 0.001), and having an unknown origin of referral (p = 0.08) were associated with a higher likelihood of LP. Advanced liver disease was identified in 533 (23%) patients and late‑stage liver disease in 124 (5.4%). LP, including with irreversible liver damage, to viral hepatitis
specialist care is frequent in Spain, despite being a country with unrestricted treatment access. Initiatives to reduce LP should specifically target men, older individuals, foreign‑born populations for CHB, and Spanish nationals for CHC
Modelando o BSC para as Universidades do Sistema ACAFE
As Instituições de Ensino Superior (IES), percebendo o acirramento da concorrência, reconhecem a importância de repensar sua forma de gestão, buscando uma visão mais competitiva e continuada. Assim, com o objetivo de contribuir para a gestão estratégica dessas instituições, especificamente as pertencentes ao sistema ACAFE, foi utilizada neste estudo a ferramenta de gestão Balanced Scorecard (BSC). Algumas etapas foram necessárias à sua adequação à s universidades fundacionais catarinenses. Apresentaram-se e identificaram-se algumas caracterÃsticas existentes no ambiente das universidades fundacionais catarinenses e suas peculiaridades em relação a outras organizações que não integram esse setor; realizaram-se os ajustes necessários à ferramenta Balanced Scorecard à s universidades do sistema ACAFE; bem como a proposta da ferramenta auxiliar denominado mapa estratégico. Por último demonstrou-se a possibilidade de se desenvolver e utilizar o BSC acadêmico institucional como forma de integrar mais de um campus a gestão focada na estratégia.Balanced Scorecard, BSC, Universidades, ACAFE
Using Genetic Algorithms to Improve Support Vector Regression in the Analysis of Atomic Spectra of Lubricant Oils
[Abstract] Purpose
– The purpose of this paper is to assess the quality of commercial lubricant oils. A spectroscopic method was used in combination with multivariate regression techniques (ordinary multivariate multiple regression, principal components analysis, partial least squares, and support vector regression (SVR)).
Design/methodology/approach
– The rationale behind the use of SVR was the fuzzy characteristics of the signal and its inherent ability to find nonlinear, global solutions in highly complex dimensional input spaces. Thus, SVR allows extracting useful information from calibration samples that makes it possible to characterize physical-chemical properties of the lubricant oils.
Findings
– A dataset of 42 spectra measured from oil standards was studied to assess the concentration of copper into the oils and, thus, evaluate the wearing of the machinery. It was found that the use of SVR was very advantageous to get a regression model.
Originality/value
– The use of genetic algorithms coupled to SVR was considered in order to reduce the time needed to find the optimal parameters required to get a suitable prediction model
Supercritical carbon dioxide extraction of lipids from Eucalyptus globulus wood
7 páginas, 2 tablas, 1 gráfico, 10 referencias.Various typical lipid components of wood extractives have been isolated from Eucalyptus globulus wood by supercritical carbon dioxide modified with methanol. The influence of various extraction parameters on the yield and qualitative composition of the extracts have been studied.
The extracts were analyzed by gas chromatography–mass spectrometry and compared with those obtained by Soxhlet extraction with acetone, the standard method for the determination of wood extractives. The qualitative and quantitative results obtained by both methods were in good
agreement. The experimental planning to asses the influence of pressure, temperature and percentage of methanol and their interactions on the extraction efficiency was carried out with a factorial design, followed by multiple linear regression algorithm.This research has been supported by the projects PB95-0079 (Spanish CICYT) and FAIR CT95-0560 (UE-Commission).Peer reviewe
Expansion of the agricultural frontier in the largest South American Dry Forest: Identifying priority conservation areas for snakes before everything is lost
Conservation planning relies on integrating existing knowledge, social-environmental contexts, and potential threats to identify gaps and opportunities for action. Here we present a case study on how priority areas for conservation can be determined using existing information on biodiversity occurrence and threats. Specifically, our goals are: (1) to model the ecological niche of twelve endemic snake species in the Dry Chaco Forest, (2) to quantify the impact of the deforestation rates on their distributions, (3) to propose high priority areas for conservation in order to improve the actual protected area system, and (4) to evaluate the influence of the human footprint on the optimization of selected priority areas. Our results demonstrate that Argentinian Dry Chaco represent, on average, ~74% of the distribution of endemic snake species and deforestation has reduced suitable areas of all snake species in the region. Further, the current protected areas are likely insufficient to conserve these species as only very low percentages (3.27%) of snakes’ ranges occur within existing protected areas. Our models identified high priority areas in the north of the Chaco forest where continuous, well-conserved forest still exists. These high priority areas include transition zones within the foothill forest and areas that could connect patches of forest between the western and eastern Chaco forest. Our findings identify spatial priorities that minimize conflicts with human activities, a key issue for this biodiversity hotspot area. We argue that consultation with stakeholders and decision-makers are urgently needed in order to take concrete actions to protect the habitat, or we risk losing the best conservation opportunities to protect endemic snakes that inhabit the Argentinian Dry Chaco.Fil: Andrade Díaz, Soledad María. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Bio y Geociencias del Noroeste Argentino. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Instituto de Bio y Geociencias del Noroeste Argentino; ArgentinaFil: Sarquis, Juan Andrés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; ArgentinaFil: Loiselle, Bette A.. University of Florida; Estados UnidosFil: Giraudo, Alejandro Raul. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; Argentina. University of Florida; Estados Unidos. Universidad Nacional del Litoral. Facultad de Humanidades y Ciencias; ArgentinaFil: Diaz Gomez, Juan Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Bio y Geociencias del Noroeste Argentino. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Instituto de Bio y Geociencias del Noroeste Argentino; Argentin
Hybrid Model Based on Genetic Algorithms and SVM Applied to Variable Selection Within Fruit Juice Classification
Research article[Abstract] Given the background of the use of Neural Networks in problems of apple juice classification, this paper aim at implementing a newly developed method in the field of machine learning: the Support Vector Machines (SVM). Therefore, a hybrid model that combines genetic algorithms and support vector machines is suggested in such a way that, when using SVM as a fitness function of the Genetic Algorithm (GA), the most representative variables for a specific classification problem can be selected
Supercritical carbon dioxide extraction of lipids from Eucalyptus globulus wood
7 páginas, 2 tablas, 1 gráfico, 10 referencias.Various typical lipid components of wood extractives have been isolated from Eucalyptus globulus wood by supercritical carbon dioxide modified with methanol. The influence of various extraction parameters on the yield and qualitative composition of the extracts have been studied.
The extracts were analyzed by gas chromatography–mass spectrometry and compared with those obtained by Soxhlet extraction with acetone, the standard method for the determination of wood extractives. The qualitative and quantitative results obtained by both methods were in good
agreement. The experimental planning to asses the influence of pressure, temperature and percentage of methanol and their interactions on the extraction efficiency was carried out with a factorial design, followed by multiple linear regression algorithm.This research has been supported by the projects PB95-0079 (Spanish CICYT) and FAIR CT95-0560 (UE-Commission).Peer reviewe
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