Subjects -> ENGINEERING (Total: 2844 journals)
    - CHEMICAL ENGINEERING (247 journals)
    - CIVIL ENGINEERING (248 journals)
    - ELECTRICAL ENGINEERING (176 journals)
    - ENGINEERING (1448 journals)
    - ENGINEERING MECHANICS AND MATERIALS (451 journals)
    - HYDRAULIC ENGINEERING (62 journals)
    - INDUSTRIAL ENGINEERING (97 journals)
    - MECHANICAL ENGINEERING (115 journals)

ENGINEERING (1448 journals)            First | 1 2 3 4 5 6 7 8     

Showing 1201 - 1205 of 1205 Journals sorted alphabetically
Purinergic Signalling     Hybrid Journal   (Followers: 1)
Quaderns d’Història de l’Enginyeria     Open Access  
Quality and Reliability Engineering International     Hybrid Journal   (Followers: 15)
Quality Engineering     Hybrid Journal   (Followers: 12)
Quantum Engineering     Hybrid Journal  
R&D Journal     Open Access   (Followers: 1)
Radiochimica Acta     Hybrid Journal   (Followers: 5)
Rare Metals     Hybrid Journal   (Followers: 3)
Reactive and Functional Polymers     Hybrid Journal   (Followers: 5)
Recent Patents on Engineering     Hybrid Journal   (Followers: 3)
Recent Patents on Nanotechnology     Hybrid Journal   (Followers: 2)
Recherche Transports Sécurité     Hybrid Journal   (Followers: 1)
Redes de Ingeniería     Open Access  
Regional Maritime University Journal     Full-text available via subscription   (Followers: 3)
Regular and Chaotic Dynamics     Hybrid Journal  
Rem : Revista Escola de Minas     Open Access  
Remote Sensing     Open Access   (Followers: 54)
Remote Sensing Letters     Hybrid Journal   (Followers: 46)
Requirements Engineering     Hybrid Journal   (Followers: 3)
Research Ideas and Outcomes     Open Access   (Followers: 1)
Research in Engineering Design     Hybrid Journal   (Followers: 10)
Research Journal of Nanoscience and Nanotechnology     Open Access   (Followers: 18)
Resonance     Hybrid Journal   (Followers: 29)
Respuestas     Open Access  
Results in Engineering     Open Access  
Review of Symbolic Logic     Full-text available via subscription   (Followers: 2)
Reviews in Advanced Sciences and Engineering     Partially Free   (Followers: 1)
Revista AIDIS de Ingeniería y Ciencias Ambientales. Investigación, desarrollo y práctica     Open Access  
Revista Brasileira de Engenharia Agrícola e Ambiental     Open Access   (Followers: 1)
Revista Brasileira de Inovação     Open Access  
Revista Campus     Open Access  
Revista Ciencia y Tecnología     Open Access  
Revista Ciencia y Tecnología     Open Access  
Revista Ciencia y Tecnología El Higo     Open Access   (Followers: 2)
Revista Científica de la UCSA     Open Access  
Revista Colombiana fe Technologias de Avanzada (RCTA)     Open Access   (Followers: 3)
Revista Cubana de Ingeniería     Open Access  
Revista de Ciências Exatas Aplicadas e Tecnológicas da Universidade de Passo Fundo : CIATEC-UPF     Open Access  
Revista de Ciências Exatas e Tecnologia     Open Access   (Followers: 1)
Revista de Ingeniería     Open Access  
Revista de Ingenieria Sismica     Open Access  
Revista de Investigación     Open Access  
Revista de Investigación, Desarrollo e Innovación     Open Access  
Revista de Investigaciones en Energía, Medio Ambiente y Tecnología     Open Access  
Revista de la Universidad del Zulia     Open Access  
Revista EIA     Open Access   (Followers: 1)
Revista Facultad de Ingeniería     Open Access   (Followers: 1)
Revista Facultad de Ingenieria - Universidad de Tarapaca     Open Access   (Followers: 1)
Revista Facultad de Ingeniería Universidad de Antioquia     Open Access   (Followers: 1)
Revista Fatec Zona Sul : REFAS     Open Access  
Revista Iberoamericana de Automática e Informática Industrial RIAI     Open Access  
Revista Informador Técnico     Open Access   (Followers: 1)
Revista Ingenieria de Construcción     Open Access   (Followers: 1)
Revista Interdisciplinar de Pesquisa em Engenharia     Open Access   (Followers: 1)
Revista Internacional de Métodos Numéricos para Cálculo y Diseño en Ingeniería     Open Access  
Revista Logos Ciencia & Tecnología     Open Access   (Followers: 1)
Revista Técnica de la Facultad de Ingeniería : Universidad del Zulia     Open Access   (Followers: 1)
Revista Tecnología en Marcha     Open Access  
Revista Tecnológica     Open Access   (Followers: 1)
Revista UIS Ingenierías     Open Access  
Revue de Métallurgie     Full-text available via subscription  
RUDN Journal of Engineering Researches     Open Access   (Followers: 1)
Russian Engineering Research     Hybrid Journal  
Russian Journal of Non-Ferrous Metals     Hybrid Journal   (Followers: 21)
Russian Microelectronics     Hybrid Journal   (Followers: 1)
Sadhana     Open Access   (Followers: 10)
Safety Science     Hybrid Journal   (Followers: 28)
Scholedge International Journal of Multidisciplinary & Allied Studies     Open Access   (Followers: 3)
Science & Technique     Open Access   (Followers: 1)
Science and Education : Scientific Publication of BMSTU     Open Access   (Followers: 1)
Science and Engineering Ethics     Hybrid Journal   (Followers: 9)
Science and Technology     Open Access   (Followers: 2)
Science and Technology Indonesia     Open Access   (Followers: 1)
Science China Technological Sciences     Hybrid Journal   (Followers: 1)
Science in Context     Hybrid Journal   (Followers: 4)
Science Journal of Volgograd State University. Technology and innovations     Open Access  
Science Progress     Full-text available via subscription   (Followers: 4)
Sciences & Technologie B : Sciences de l'ingénieur     Open Access  
Scientia cum Industria     Open Access  
Scientific Drilling     Open Access  
Scientific Journal of Control Engineering     Open Access   (Followers: 3)
Scientific Journal of Mehmet Akif Ersoy University     Open Access  
Scientific Journal of Pure and Applied Sciences     Open Access   (Followers: 1)
SCITECH Nepal     Open Access  
Sealing Technology     Full-text available via subscription   (Followers: 1)
Securitas Vialis     Hybrid Journal  
Security and Communication Networks     Hybrid Journal   (Followers: 2)
Selcuk University Journal of Engineering, Science and Technology     Open Access   (Followers: 2)
Selected Topics in Applied Earth Observations and Remote Sensing, IEEE Journal of     Hybrid Journal   (Followers: 57)
Semiconductors     Hybrid Journal   (Followers: 2)
Semiconductors and Semimetals     Full-text available via subscription   (Followers: 1)
Sensing and Imaging : An International Journal     Hybrid Journal   (Followers: 2)
Sensor Letters     Full-text available via subscription   (Followers: 2)
Sensors     Open Access   (Followers: 23)
Separation and Purification Technology     Hybrid Journal   (Followers: 15)
Shock and Vibration     Hybrid Journal   (Followers: 26)
SIAM Journal on Applied Dynamical Systems     Hybrid Journal   (Followers: 2)
SIAM Journal on Mathematical Analysis     Hybrid Journal   (Followers: 4)
SIAM Journal on Matrix Analysis and Applications     Hybrid Journal   (Followers: 3)
SIAM Journal on Numerical Analysis     Hybrid Journal   (Followers: 7)
SIAM Journal on Optimization     Hybrid Journal   (Followers: 11)
SIAM Review     Hybrid Journal   (Followers: 7)
SILICON     Hybrid Journal  
SINERGI     Open Access  
Sistemas & Telemática     Open Access   (Followers: 2)
Sleep and Biological Rhythms     Hybrid Journal   (Followers: 9)
Small     Hybrid Journal   (Followers: 16)
Smart Grid     Open Access   (Followers: 1)
SN Applied Sciences     Hybrid Journal   (Followers: 1)
Sociología y Tecnociencia     Open Access  
Soft Computing     Hybrid Journal   (Followers: 9)
Soil Dynamics and Earthquake Engineering     Hybrid Journal   (Followers: 15)
Solar RRL     Hybrid Journal  
Soldagem & Inspeção     Open Access  
SourceOCDE Developpement urbain, rural et regional     Full-text available via subscription   (Followers: 1)
SourceOCDE Energie     Full-text available via subscription  
SourceOECD Energy     Full-text available via subscription  
SourceOECD Science and Technology Statistics - SourceOCDE Base de donnees des sciences et de la technologie     Full-text available via subscription  
SourceOECD Transport     Full-text available via subscription   (Followers: 2)
SourceOECD Urban, Rural and Regional Development     Full-text available via subscription  
South African Computer Journal     Full-text available via subscription  
South African Journal of Agricultural Extension     Open Access   (Followers: 4)
South African Journal of Science     Open Access   (Followers: 4)
Sports Engineering     Hybrid Journal   (Followers: 2)
Stahlbau     Hybrid Journal   (Followers: 2)
Steel in Translation     Hybrid Journal   (Followers: 1)
Steel Research International     Hybrid Journal   (Followers: 24)
Stochastic Analysis and Applications     Hybrid Journal   (Followers: 2)
Stochastic Processes and their Applications     Hybrid Journal   (Followers: 5)
Stochastics and Dynamics     Hybrid Journal  
Strain     Hybrid Journal   (Followers: 2)
Strategic Planning for Energy and the Environment     Hybrid Journal   (Followers: 4)
Studies in Engineering and Technology     Open Access  
Studies in Interface Science     Full-text available via subscription  
Studies in Logic and Practical Reasoning     Full-text available via subscription  
Studies in Surface Science and Catalysis     Full-text available via subscription   (Followers: 1)
Sud-Sciences et Technologies     Open Access   (Followers: 1)
Superconductor Science and Technology     Hybrid Journal   (Followers: 3)
Surface Engineering     Hybrid Journal   (Followers: 1)
Surface Review and Letters     Hybrid Journal   (Followers: 1)
Surface Science Reports     Full-text available via subscription   (Followers: 20)
Surfaces and Interfaces     Hybrid Journal  
Survey Review     Hybrid Journal   (Followers: 6)
Surveying and Land Information Science     Full-text available via subscription   (Followers: 1)
Surveys in Operations Research and Management Science     Hybrid Journal   (Followers: 3)
Sustainability Science     Open Access   (Followers: 9)
Sustainability Science and Engineering     Full-text available via subscription   (Followers: 3)
Sustainable Management of Sediment Resources     Full-text available via subscription  
Swiss Journal of Geosciences     Hybrid Journal   (Followers: 1)
Symmetry     Open Access   (Followers: 1)
Synthesis Lectures on Algorithms and Software in Engineering     Full-text available via subscription   (Followers: 3)
Synthesis Lectures on Antennas     Full-text available via subscription   (Followers: 5)
Synthesis Lectures on Biomedical Engineering     Full-text available via subscription  
Synthesis Lectures on Computational Electromagnetics     Full-text available via subscription   (Followers: 4)
Synthesis Lectures on Energy and the Environment: Technology, Science, and Society     Full-text available via subscription   (Followers: 1)
Synthesis Lectures on Engineering     Full-text available via subscription  
Synthesis Lectures on Global Engineering     Full-text available via subscription  
Synthesis Lectures on Professionalism and Career Advancement for Scientists and Engineers     Full-text available via subscription   (Followers: 2)
Synthetic Metals     Hybrid Journal   (Followers: 4)
Systems Engineering     Hybrid Journal   (Followers: 7)
Systems Engineering - Theory & Practice     Full-text available via subscription  
Systems Engineering Procedia     Open Access  
Systems Research Forum     Hybrid Journal   (Followers: 1)
Systems Science & Control Engineering     Open Access   (Followers: 8)
Tableros     Open Access   (Followers: 2)
Tapuya : Latin American Science, Technology and Society     Open Access   (Followers: 1)
Technical Tips Online     Full-text available via subscription   (Followers: 1)
Technological Engineering     Open Access   (Followers: 1)
Technologies     Open Access   (Followers: 2)
TECHNOLOGY     Hybrid Journal   (Followers: 1)
Technology and Economics of Smart Grids and Sustainable Energy     Hybrid Journal  
Technology and Innovation     Full-text available via subscription   (Followers: 4)
Technology in Society     Hybrid Journal   (Followers: 7)
Technometrics     Full-text available via subscription   (Followers: 9)
Tecnología y Ciencia     Open Access  
Tecnología y Sociedad     Open Access   (Followers: 1)
TecnoLógicas     Open Access  
Tecnura     Open Access   (Followers: 1)
Tekhné     Open Access   (Followers: 1)
Tekniikan Waiheita     Open Access  
Teknologi dan Kejuruan : Jurnal Teknologi, Kejuruan, dan Pengajarannya     Open Access  
Telecommunications Policy     Hybrid Journal   (Followers: 9)
Textile Science and Technology     Full-text available via subscription   (Followers: 4)
Thalassas : An International Journal of Marine Sciences     Hybrid Journal  
The Engineer     Partially Free  
The Journal of Supercomputing     Hybrid Journal   (Followers: 1)
The Scientific World Journal     Open Access  
Theoretical and Computational Fluid Dynamics     Hybrid Journal   (Followers: 17)
Theoretical Issues in Ergonomics Science     Hybrid Journal   (Followers: 7)
Thermal Engineering     Full-text available via subscription   (Followers: 10)
Tikrit Journal of Engineering Science     Open Access  
tm - Technisches Messen     Hybrid Journal   (Followers: 2)
Topics in Catalysis     Hybrid Journal   (Followers: 1)
Traffic Injury Prevention     Hybrid Journal   (Followers: 75)
Transactions of the Indian National Academy of Engineering     Hybrid Journal   (Followers: 2)
Transactions of the VŠB – Technical University of Ostrava, Safety Engineering Series     Open Access   (Followers: 1)
Transactions of Tianjin University     Full-text available via subscription  
Transport and Aerospace Engineering     Open Access   (Followers: 13)
Transport and Telecommunication     Open Access   (Followers: 4)
Transport World Africa     Full-text available via subscription   (Followers: 2)

  First | 1 2 3 4 5 6 7 8     

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Revista Brasileira de Engenharia Agrícola e Ambiental
Journal Prestige (SJR): 0.541
Citation Impact (citeScore): 1
Number of Followers: 1  

  This is an Open Access Journal Open Access journal
ISSN (Print) 1415-4366 - ISSN (Online) 1807-1929
Published by SciELO Homepage  [911 journals]
  • Water productivity with localized irrigation using groundwater and reuse
           water in the cultivation of plant species

    • Abstract: ABSTRACT This study aimed to analyze the water saving potential of replacing the traditional, furrow-irrigated banana crop in the Curu-Pentecoste Irrigated Perimeter with localized systems by inserting new cropping plans and sources of groundwater and reuse water. An analysis of the support capacity in shallow tube wells for irrigation was also performed, considering the scenario of full recharge and water scarcity. The economic analysis was performed using the profitability indicators of the investment analysis: benefit/cost ratio, net present value, internal rate of return and payback period. Water productivity data reveal that cropping plans associated with alternative sources of water from shallow tube wells and reuse of the excess surface irrigation water in localized systems are economically more attractive than traditional, furrow-irrigated banana crop. The support capacity of shallow tube wells reveals that the exploitation of this underground water resource in the region is a viable alternative for irrigation of small areas. With the exception of banana, the other scenarios analyzed showed positive cash flows from the second year.RESUMO Objetivou-se neste estudo analisar o potencial de economia de água da substituição do cultivo tradicional da bananeira irrigada por sulcos no Perímetro Irrigado Curu-Pentecoste por sistemas localizados mediante a inserção de novos planos de ocupação e fontes de água subterrânea e de reúso. Realizou-se, também, análise da capacidade de suporte em poços rasos tubulares para irrigação, considerando o cenário de recarga plena e de escassez hídrica. A análise econômica foi realizada por meio dos indicadores de rentabilidade da análise de investimento: relação benefício/custo, valor presente líquido, taxa interna de retorno e período payback. Os dados de produtividade da água revelam que os planos de cultivo associados às alternativas de fontes hídricas provenientes de poço raso tubular e de reúso do excesso da irrigação por superfície em sistemas localizados são mais atrativos do ponto de vista econômico que o cultivo tradicional da bananeira irrigada por sulcos. A capacidade de suporte dos poços rasos tubulares revela que a exploração deste recurso hídrico subterrâneo na região é alternativa viável para irrigação de pequenas áreas. À exceção da bananeira, os demais cenários analisados demonstraram fluxos de caixa positivos a partir do segundo ano.
       
  • Fuzzy modeling of the risk of cacao moniliasis occurrence in Bahia state,
           Brazil

    • Abstract: ABSTRACT This work aimed to determine potential areas for the establishment of cocoa moniliasis in Bahia state, Brazil, by means of fuzzy logic, based on historical datasets of temperature and air relative humidity, available for 519 measurement points distributed throughout the state of Bahia. The data were initially submitted to a descriptive statistical analysis. The spatial variability was determined through geostatistical analysis, followed by interpolation to map the spatial-temporal structure dependence of the phenomenon. Simulations of continuous pixel-to-pixel classification of variables were performed using fuzzy mapping to model the climatic risk of disease establishment. The exponential fuzzy model was applied to temperature data, while the linear model was used for air relative humidity data. The potential areas were defined for each month, using data of temperature and air relative humidity. The fuzzy models used allowed for modeling of the climatic risk of cocoa moniliasis establishment. A large area of the state is at high risk of disease, thus requiring mitigating measures to avoid the pathogen’s introduction and dissemination.RESUMO Com este trabalho objetivou-se definir áreas potenciais de estabelecimento da monilíase do cacaueiro no Estado da Bahia, por meio da lógica fuzzy, com base em séries históricas de temperatura e umidade relativa do ar, disponíveis para 519 pontos de medição distribuídos no Estado da Bahia. Os dados foram submetidos inicialmente a uma análise estatística descritiva. A variabilidade espacial foi determinada através de análise geoestatística, seguida de interpolações para mapear a estrutura da dependência espaço-temporal do fenômeno. Para modelar o risco climático de estabelecimento da doença foram realizadas simulações de classificação contínua, pixel-a-pixel, das representações das variáveis, utilizando o mapeamento fuzzy. Aos dados de temperatura, aplicou-se o modelo fuzzy exponencial, enquanto que aos dados de umidade relativa do ar, o modelo utilizado foi o linear. As definições de áreas potenciais foram realizadas para cada mês, utilizando a informação conjunta das pertinências da temperatura e da umidade relativa do ar. Os modelos fuzzy utilizados permitiram modelar o risco climático de estabelecimento da monilíase no Estado da Bahia. A maior extensão do Estado da Bahia tem riscos elevados para o desenvolvimento da doença, o que exige medidas mitigadoras para evitar a introdução e disseminação do patógeno.
       
  • No-tillage curly lettuce cultivated under different spacings

    • Abstract: ABSTRACT The use of appropriate cultural practices is important for the sustainability of the production system. This study aims to evaluate the agronomic performance of lettuce cultivar ‘Mônica’, during two crop cycles, at the Instituto Federal Catarinense, Campus of Concórdia, SC, Brazil. Two experiments were conducted in the field, arranged in randomized block design, in a 3 x 2 factorial scheme, evaluating the effects of three spacings (0.20 × 0.20, 0.25 × 0.25 and 0.30 × 0.30 m), associated with two planting systems (conventional and no-tillage with millet), with four repetitions in the first cycle and five in the second. At 39 and 44 days after transplanting, six plants were harvested in the first and in the second cycles, respectively. Soil temperature, fresh and dry mass of the spontaneous plants, dry mass of roots, plant diameter, number of marketable leaves, fresh and dry mass of the plants were evaluated. Lettuce cultivated under no-tillage at larger spacings resulted in higher yield per plant, but higher yield per area was observed at smaller spacing. No-tillage reduced spontaneous plants and soil temperature in the West of Santa Catarina.RESUMO O uso de práticas culturais adequadas é importante para a sustentabilidade do sistema de produção. Este estudo objetiva avaliar o desempenho agronômico da cultivar de alface ‘Mônica’, durante dois ciclos de cultivo, no Instituto Federal Catarinense, Campus Concórdia, SC. Foram conduzidos dois experimentos no campo, dispostos em blocos casualizados, em esquema fatorial 3 x 2, sendo avaliados os efeitos de três espaçamentos (0,20 × 0,20; 0,25 × 0,25 e 0,30 × 0,30 m), associados a dois sistemas de plantio (convencional e plantio direto com milheto), com quatro repetições no primeiro ciclo e cinco no segundo. Decorridos 39 e 44 dias após o transplante foi feita a colheita de 6 plantas centrais no primeiro e no segundo ciclo, respectivamente. Foram avaliados a temperatura do solo, massa fresca e seca das plantas espontâneas, massa seca das raízes, diâmetro da planta, número de folhas comerciais por planta, massa fresca e seca das plantas. A alface cultivada em plantio direto em espaçamentos maiores obteve maior produtividade por planta, contudo, maior produtividade por área foi observada em menor espaçamento. O plantio direto reduziu as plantas espontâneas e a temperatura do solo no Oeste Catarinense.
       
  • Nitrogen and mepiquat chloride can affect fiber quality and cotton yield

    • Abstract: ABSTRACT The use of mepiquat chloride (MC) in cotton (Gossypium hirsutum L.) cultivation has increased significantly in recent years. The use of MC, a growth regulator, results in higher precocity and lower height and consequently increases yield and reduces crop costs. The objective of this study was to evaluate the effects of nitrogen (N) and MC doses on fiber quality and cotton yield. This study was conducted during the 2012/13 and 2013/14 harvests in the experimental area of the Fundação de Apoio à Pesquisa Agropecuária de Chapadão, located in the municipality of Chapadão do Sul, MS, Brazil, at 18° 48’ 45.9” S, 52° 36’ 3” W, having an altitude of 820 m. The experimental design was a randomized blocks in a 5 × 4 factorial scheme comprised of five N doses (0, 40, 80, 120, 160 kg ha-1) and four MC doses (0, 50, 100, 150 mL ha-1) with four repetitions. Analyses of fiber quality included: length, uniformity, elongation, strength, micronaire index, reflectance, yellowing degrees and short fiber content. Regarding cotton yield, green color index (GCI), plant height at harvest time, and cotton seed yield were determined. The best results for fiber quality and productivity occurr with the application of 76.8 mL ha-1 of MC to the cotton crops when the N dose is greater than 80 kg ha-1. Increasing N doses causes an increase in cotton yield and micronaire index, but there is a decrease in fiber uniformity.RESUMO O uso do cloreto de mepiquat (CM) no cultivo de algodão (Gossypium hirsutum L.) aumentou significativamente nos últimos anos. O uso do CM, um regulador de crescimento, resulta em maior precocidade e menor altura e, consequentemente, aumento da produtividade e redução dos custos da cultura. O objetivo deste estudo foi avaliar os efeitos de doses de nitrogênio e CM sobre a qualidade da fibra e produtividade do algodoeiro. O estudo foi conduzido nas safras 2012/13 e 2013/14, na área experimental da Fundação de Apoio à Pesquisa Agropecuária de Chapadão, em Chapadão do Sul, MS, a 18o 48’ 45,9” S, 52o 36’ 3” W, com altitude de 820 m. O delineamento experimental foi em blocos casualizados em esquema fatorial 5 x 4, correspondendo a cinco doses de N (0, 40, 80, 120, 160 kg ha-1) e quatro doses de CM (0, 50, 100, 150 mL ha-1) com quatro repetições. As avaliações realizadas para análises da qualidade da fibra foram: comprimento, uniformidade, elongação, resistência, índice micronaire, reflectância, graus de amarelecimento e conteúdo de fibras curtas. Para a produtividade do algodão foram feitas análises de índice de cor verde (ICV), altura de plantas no momento da colheita e produtividade do algodão em caroço. Os melhores resultados em qualidade de fibras e produtividade ocorrem com a aplicação de 76,8 mL ha-1 de CM no algodoeiro quando a dose de N é maior que 80 kg ha-1. Doses crescentes de N causam aumento na produtividade de algodão e no índice micronaire, porém há uma diminuição na uniformidade de fibras.
       
  • Critical nitrogen dilution curves and productivity assessments for plant
           cane

    • Abstract: ABSTRACT Nitrogen is the most limiting nutrient for the development of sugarcane and particularly the use of more productive and demanding varieties, for which the doses of nitrogen fertilization necessary during the plant cane cycle may be underestimated and the critical levels of nitrogen in the leaf may be modified. The objective of this study was to determine the critical nitrogen dilution curve (CNDC) for leaves, evaluate the aboveground dry mass production (DM) and productivity of two varieties fertilized with N in the plant cane cycle. The study was conducted under field conditions, evaluating two sugarcane varieties RB92579 and RB867515, fertilized with seven doses of N (0, 30, 60, 90, 120, 150 and 200 kg ha-1). The varieties and doses were arranged in randomized blocks and analyzed in the 2 × 7 factorial scheme. It was found that the nitrogen concentration in the leaf decreased with four repetitions increase in DM yield and adjusted an exponential model, which enabled to estimate the critical levels of 13.03 and 12.46 g N kg-1 dry matter in the varieties RB92579 and RB867515, respectively. The plant cane cycle were observed to respond positively to nitrogen fertilization, with increase of 18.66% in tons of stalk per hectare (TSH) in response to the application addition of up to 129.45 kg N ha-1. The variety RB92579 showed the lowest dilution of the critical nitrogen concentration, the highest production of DM and higher stalk yield, and accordingly is considered to be the more efficient of the two varieties with respect to nitrogen fertilizer utilization.RESUMO O nitrogênio (N) é o nutriente mais limitante ao desenvolvimento da cana-de-açúcar e com a utilização de variedades mais produtivas e exigentes, as doses utilizadas na adubação nitrogenada na cana planta podem estar subestimadas e os teores críticos de N na folha poderão sofrer modificações. O objetivo da pesquisa foi determinar a curva de diluição dos teores críticos de N (CNDC) na folha, avaliar a produção da massa seca da parte aérea (ADM) e a produtividade de duas variedades de cana-de-açúcar em relação à adubação nitrogenada. A pesquisa foi realizada em condições de campo, sendo avaliadas as variedades RB92579 e RB867515, quando adubadas com sete doses de N (0, 30, 60, 90, 120, 150 e 200 kg ha-1). As variedades e doses de N foram dispostas em blocos casualizados com quatro repetições sob o esquema fatorial de 2 × 7. O teor de N na folha reduziu com o aumento da ADM e se ajustou ao modelo exponencial que permitiu estimar os teores críticos de 13,03 e 12,46 g de N kg-1 de matéria seca nas variedades RB92579 e RB867515, respectivamente. A cana planta respondeu positivamente à adubação nitrogenada e aumentou em 18,66% a tonelada de colmos por hectare (TCH) com adição de até 129,45 kg ha-1 de N. A variedade RB92579 apresentou menor diluição do teor crítico do N, maior produção de ADM e maior produtividade de colmos, sendo considerada mais eficiente na utilização do N-fertilizante.
       
  • Evapotranspiration and crop coefficients in two irrigated wheat cultivars

    • Abstract: ABSTRACT In the state of Mato Grosso, Brazil, wheat is an alternative to the current production system, mainly in irrigated crops, with new cultivars improved for this environment and system. The objective was to determine the evapotranspiration of the irrigated wheat crop and the dual coefficients of cultivars for the Brazilian Midwest. The experiment was conducted in the field using 12 weighing lysimeters and mini-lysimeters, filled by soil monoliths. The wheat cultivars BRS-254 and BRS-394 were used in the first and second years, respectively. Reference evapotranspiration was obtained by the Penman-Monteith equation and crop evapotranspiration by the mass difference in the lysimeters. Basal crop coefficient and soil water evaporation coefficient were determined according to the crop development stages in both years of cultivation. The mean ETc and ETo values were 3.87, 3.49 mm d-1 and 4.10 and 3.23 mm d-1, respectively, in the first and second cultivation cycles, with higher values of ETc recorded in the reproductive stages of the crop, flowering and grain filling. The basal crop coefficients and soil water evaporation coefficients estimated by weighing lysimeters composed of soil monoliths are: Kcb - 0.42, 0.78, 0.94, 0.74 and 0.47 and Ke - 0.72, 0.52, 0.39, 0.58 and 0.13 for the cultivar BRS-254, and Kcb - 0.28, 0.27, 0.65, 0.98 and 0.66 and Ke - 1.04, 0.96, 0.65, 0.34 and 0.51 for the cultivar BRS-394, at the stages of emergence, tillering, flowering, maturation and harvest, respectively.RESUMO No estado do Mato Grosso, a cultura do trigo surge como alternativa ao sistema produtivo atual, principalmente em cultivos irrigados, com novas cultivares melhoradas para este ambiente e sistema. Objetivou-se determinar a evapotranspiração da cultura (ETc) do trigo irrigado e os coeficientes duplos de cultivo de cultivares para o Centro-Oeste brasileiro. O experimento foi realizado no campo utilizando 12 lisímetros e minilisímetros de pesagem, preenchidos por monólitos de solo. Foram utilizadas as cultivares de trigo BRS-254 e BRS-394 no primeiro e segundo ano, respectivamente. A evapotranspiração de referência (ETo) foi obtida pela equação de Penman-Monteith e da cultura por diferença de massa nos lisímetros utilizados para determinar o coeficiente de evaporação de água do solo. Foram determinados os coeficientes basais de cultivo e de evaporação de água do solo conforme os estádios de desenvolvimento da cultura nos dois anos de cultivo. Os valores médios de ETc e ETo foram de 3,87, 3,49 mm d-1 e de 4,10 e 3,23 mm d-1, respectivamente, no primeiro e no segundo ciclos de cultivo, com maiores valores de ETc registrados nas fases reprodutivas da cultura, florescimento e enchimento de grãos. Os coeficientes basais de cultivo e os coeficientes de evaporação de água do solo estimados por lisímetros de pesagem preenchidos por monólitos de solo são: Kcb - 0,42, 0,78, 0,94, 0,74 e 0,47 e Ke - 0,72, 0,52, 0,39, 0,58 e 0,13 para a cultivar BRS-254, e Kcb - 0,28, 0,27, 0,65, 0,98 e 0,66 e Ke - 1,04, 0,96, 0,65, 0,34 e 0,51 para a cultivar BRS-394, nos estádios de emergência, perfilhamento, florescimento, maturação e colheita, respectivamente.
       
  • Salinity and flow rates of nutrient solution on cauliflower biometrics in
           NFT hydroponic system

    • Abstract: ABSTRACT The use of brackish water in hydroponic crops represents an alternative for vegetable production. In this context, two experiments were conducted to evaluate the effect of using brackish water to prepare the nutrient solution and replace the evapotranspired depth, applied at different flow rates, on cauliflower biometrics in NFT (nutrient film technique) hydroponic system. In both experiments, the experimental design was completely randomized with four repetitions, in a 6 x 2 factorial scheme: six levels of water electrical conductivity (ECw) in interaction with two flow rates of nutrient solution application in the hydroponic channels (1.5 and 2.5 L min-1). In Experiment I, brackish waters with different EC (1.5, 2.5, 3.5, 4.5 and 5.5 dS m-1), obtained by the addition of NaCl in public-supply water (0.2 dS m-1), were used. In Experiment II, the chemical characteristics of brackish waters collected in the semiarid region of Pernambuco were simulated, with EC of 1.67, 3.30, 4.71, 5.88 and 13.84 dS m-1, plus the control (0.2 dS m-1). Increasing salinity reduced cauliflower growth. Flow rate of 1.5 L min-1 promoted the best results of shoot fresh and dry masses, leaf area, number of leaves, plant height and shoot diameter. The best water for cauliflower production was public-supply water and, among the well waters, the best was the calcium sulfate-rich water with EC of 1.67 dS m-1.RESUMO O uso de águas salobras em cultivos hidropônicos representa uma alternativa para a produção de hortaliças. Assim, foram conduzidos dois experimentos objetivando avaliar o uso de águas salobras, no preparo da solução nutritiva e reposição da lâmina evapotranspirada aplicadas em diferentes vazões na biometria de plantas de couve-flor em sistema hidropônico NFT (técnica do fluxo laminar de nutrientes). Nos dois experimentos, o delineamento experimental utilizado foi o inteiramente casualizado com quatro repetições, em esquema fatorial 6 x 2: seis níveis de condutividade elétrica da água (CEa) em interação com duas vazões de aplicação da solução nutritiva nos canais hidropônicos (1,5 e 2,5 L min-1). No Experimento I utilizaram-se águas salobras com diferentes CE (1,5; 2,5; 3,5; 4,5 e 5,5 dS m-1), obtidos a partir da adição de NaCl na água de abastecimento (0,2 dS m-1). No Experimento II foram simuladas as características químicas das águas salobras coletadas na região semiárida de Pernambuco, com CE de 1,67; 3,30; 4,71; 5,88 e 13,84 dS m-1, além do controle (0,2 dS m-1). O aumento da salinidade reduziu o crescimento da couve-flor. A vazão de 1,5 L min-1 foi a que proporcionou os melhores resultados para as massas fresca e seca da parte aérea, área foliar, número de folhas, altura de planta e diâmetro da parte aérea. A melhor água para a produção da couve-flor foi a de abastecimento e dentre as de poços, a melhor foi a água sulfatada cálcica de 1,67 dS m-1.
       
  • Microclimate and thermal comfort indices in silvopastoral systems under
           different planting directions and seasons

    • Abstract: ABSTRACT The orientation of tree-rows in a silvopastoral system associated with different seasons of the year allows more or less sunlight penetration, resulting in deliberate modification of the microclimate composition and thermal conditions provided to animals. In this sense, the aims of this study were to evaluate microclimatic variables and thermal comfort indices for east-west and north-south oriented silvopastoral systems, compared to unshaded systems during summer and winter. The study was conducted at the Modelo II Farm (21° 08’ S 53° 17’ W) at an altitude of 354 m. A randomized block design in scheme of split-split plots with five repetitions was adopted. Two planting directions and a control treatment (unshaded) were evaluated in the plots. Collection times were evaluated in sub-plots, and the distance from eucalyptus trees was evaluated in sub-sub-plots. Changes in the east-west and north-south planting directions did not promote changes in climate variables, nor did they change the thermal comfort indices during summer. There were differences, however, in temperature and relative humidity of the air, black globe temperature, and radiant heat load during winter. Silvopastoral systems provide improvements in the environment and, concomitantly, to the thermal comfort of animals, when compared to unshaded systems. However, thermal stress situations occur despite the presence of trees, depending on the time of the day and the distance from the rows of eucalyptus trees.RESUMO O direcionamento dos renques das árvores em sistema silvipastoril, associados a diferentes estações do ano, permite maior ou menor penetração de luz solar, resultando em expressiva modificação da composição do microclima e das condições térmicas a serem propiciadas aos animais. Neste sentido, objetivou-se avaliar as variáveis microclimáticas e índices de conforto térmico em sistemas silvipastoris orientados na direção leste-oeste e norte-sul, comparados ao sistema sem sombra nas estações de verão e inverno. O estudo foi realizado na Fazenda Modelo II (21° 08’ S 53º 17’ O, e altitude de 354 m). O delineamento adotado foi em blocos casualizados em esquema de parcelas sub-subdivididas, com cinco repetições. Nas parcelas foram avaliadas duas direções de plantio e controle (sem sombra). Nas sub-parcelas foram avaliados os horários de coleta e nas sub-subparcelas as distâncias em relação ao renque das árvores de eucalipto. As direções leste-oeste e norte-sul não promoveram alterações nas variáveis climáticas, bem como nos índices de conforto térmico durante o verão. Entretanto, diferenciaram-se para temperatura e umidade relativa do ar, temperatura do globo negro e carga térmica radiante durante o inverno. Os sistemas silvipastoris proporcionam melhoria no ambiente e concomitantemente no conforto térmico animal quando comparados ao sistema sem sombra. Todavia, mesmo na presença de árvores, ocorrem situações de estresse térmico, dependendo do horário do dia e da distância em relação aos renques de eucalipto.
       
  • Fiber-reinforced concrete for the flat bottom of silos

    • Abstract: ABSTRACT The use of synthetic fibers as reinforcement for concrete replacing the steel reinforcement has been diffused worldwide in several applications, gaining prominence in the application for industrial floors, tunnel linings, road pavements, etc., i.e., continuous structures in contact with soil that require performance in the elastic medium. The present study investigated the applicability of concrete reinforced with synthetic fibers in the bottom slab of silos supported directly on the ground, being composed of an experimental study and a case study. The experimental study consisted of the analysis of the mechanical behavior of this concrete by testing three concentrations of synthetic fibers (3.0, 4.5 and 6.0 kg m-3) in a conventional simple concrete matrix. The case study consisted of the design of this part in conventional reinforced concrete and concrete reinforced with synthetic fibers with the objective of performing an economic comparison between the two projects. The experimental results showed that the fiber concentration that contributed to a better mechanical performance of the concrete matrix was 3.0 kg m-3. The case study showed that the most economical design was the one made with fiber-reinforced concrete.RESUMO O emprego de fibras sintéticas como reforço para concretos em substituição das armaduras de aço vem sendo difundido mundialmente em diversas aplicações, ganhando destaque na aplicação para pisos industriais, revestimentos de túneis, pavimentos rodoviários, etc., isto é, estruturas contínuas em contato com o solo que requerem desempenho no meio elástico. O presente trabalho investiga a aplicabilidade do concreto reforçado com fibras sintéticas na laje de fundo de silos apoiados diretamente sobre o solo, sendo o mesmo composto por um estudo experimental e um estudo de caso. O estudo experimental resume-se na análise do comportamento mecânico desse concreto, testando-se três concentrações de fibras sintéticas (3.0, 4.5 e 6.0 kg m-3) numa matriz de concreto simples convencional. O estudo de caso consiste no dimensionamento dessa peça em concreto armado convencional e concreto reforçado com fibras sintéticas, com o objetivo de realizar um comparativo econômico entre os dois projetos. Os resultados experimentais mostraram que a concentração de fibras que contribuiu para melhor desempenho mecânico da matriz de concreto foi o de 3.0 kg m-3. O estudo de caso mostrou que o projeto mais econômico foi o dimensionado com concreto reforçado com fibras.
       
  • Isotherms and thermodynamic properties of water adsorption in
           ‘Cumari-do-Pará’ pepper seeds

    • Abstract: ABSTRACT Studies related to water sorption in seeds are essential for the design and optimization of storage systems. The objective of this research was to determine and model the adsorption isotherms and calculate the latent heat of water vaporization, differential enthalpy and entropy, the isokinetic theory and Gibbs free energy for ‘Cumari-do-Pará’ pepper seeds. The equilibrium moisture contents were obtained by the static gravimetric method at temperatures of 30, 35 and 40 °C and water activities between 0.290 and 0.900 (decimal). The Chen-Clayton model is the one that best represents the water adsorption isotherms in ‘Cumari-do-Pará’ pepper seeds under the studied conditions, with 9.94% mean relative error, 0.40 mean estimated error and random distribution of residuals. The latent heat of vaporization ranged from 2,555.669 to 3,162.180 kJ kg-1. The enthalpy, entropy and Gibbs free energy increase with the reduction in the equilibrium moisture content of the seeds. The isokinetic theory is valid for the adsorption process.RESUMO Estudos relacionados com a sorção de água em sementes são essenciais para o dimensionamento e otimização de sistemas de armazenagem. Assim, objetivou-se determinar e modelar as isotermas de adsorção e calcular o calor latente de vaporização da água, a entalpia e entropia diferencial, a teoria isocinética e a energia livre de Gibbs para as sementes de pimenta Cumari-do-Pará. Os teores de água de equilíbrio foram obtidos pelo método estático gravimétrico nas temperaturas de 30, 35 e 40 °C e atividades de água entre 0,290 a 0,900 (decimal). O modelo de Chen-Clayton é o que melhor representa as isotermas de adsorção de água em sementes de pimenta Cumari-do-Pará nas condições estudadas, apresentando 9,94% de erro médio relativo, 0,40 de erro médio estimado e distribuição aleatória dos resíduos. O calor latente de vaporização variou de 2.555,669 a 3.162,180 kJ kg-1. A entalpia, a entropia e a energia livre de Gibbs aumentam com a redução do teor de água de equilíbrio das sementes. A teoria isocinética é válida para o processo de adsorção.
       
 
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