Efeito da aplicação sucessiva de precipitações pluviais com diferentes perfis na taxa de infiltração de água no solo

O processo de infiltração é influenciado pelas condições da superfície do solo e pela precipitação pluvial. O objetivo deste trabalho foi avaliar a influência de aplicações sucessivas de precipitações pluviais com diferentes perfis na formação do encrostamento superficial e, consequentemente, na taxa de infiltração de água em solo sem cobertura e com cobertura. Foram aplicadas três precipitações pluviais sucessivas para cada perfil de precipitação pluvial, em intervalos de 24 h, sendo usados os perfis de precipitação pluvial constante, exponencial decrescente, duplo exponencial adiantado e atrasado, com uma lâmina média de 55 mm por aplicação. Buscou-se ajustar um fator de decaimento da taxa de infiltração (Ti) em função da energia cinética acumulada da chuva, denominado de fator f, dado pela razão entre a taxa de infiltração estável (Tie) com efeito da chuva e a Tie sem o efeito da chuva. Foram avaliadas duas condições de cobertura do solo, solo sem cobertura e solo coberto com palhada, sendo os ensaios de infiltração realizados com um simulador de chuvas, em parcelas experimentais de dimensões de 1,0 x 0,7 m. Os resultados foram avaliados por meio de análises gráficas, análise de variância e teste de média. Verificou-se que os diferentes perfis de precipitação pluvial não influenciaram a infiltração de água no solo, tanto para o solo sem cobertura como para o solo com cobertura, sendo esta influenciada somente pelas aplicações sucessivas, com menores valores da taxa de infiltração obtidos na segunda e terceira aplicações. O decréscimo na Ti em solo sem cobertura foi devido à formação de encrostamento superficial, o que ocorreu logo na primeira aplicação. A Tie em solo sem cobertura teve decréscimo de 75 % se comparada à Tie em solo com cobertura. A lâmina infiltrada não foi influenciado pelos quatro perfis de precipitação pluvial. O fator f foi descrito com uso de uma equação do tipo exponencial.

Modelo para estimativa da infiltração de água e perfil de umidade do solo

A adequada modelagem da infiltração de água no solo é fundamental para estimação do movimento de água, erosão hídrica, recarga e contaminação de aquíferos. Este trabalho apresenta um modelo para estimativa da infiltração de água no solo (GAML-c), com base no modelo de Green-Ampt-Mein-Larson, que provê descrição da geometria e do deslocamento da frente de umedecimento no solo. Testes experimentais foram conduzidos em Latossolo Vermelho-Amarelo para avaliar o GAML-c, usando-se quatro diferentes cenários: considerando a condutividade hidráulica do solo igual à taxa de infiltração estável (Tie) e a umidade máxima do solo igual ao teor de água na zona de transmissão (θw) (TW); condutividade hidráulica do solo igual à do solo saturado (K0) e a umidade máxima do solo igual θw (KW); condutividade hidráulica do solo igual à Tie e a umidade máxima do solo igual ao teor de água na saturação (θs) (TS); e condutividade hidráulica do solo igual a K0 e a umidade máxima do solo igual θs (KS). Verificou-se que o GAML-c no cenário TW foi o melhor estimador do perfil de umidade do solo, resultando em aceitáveis estimativas da infiltração de água.

Rintamalta kotiseurakunnan multiin

Artikkeli ilmestynyt julkaisussa: Tampereen hiippakunnan vuosikirja. 46 (1995), s. 95-100

Thermodynamic investigations in the Si-Ge-rich part of the ruthenium-silicon-germanium system

This paper reports molar heat capacities of Ru50SixGe(50-x) and Ru40SiyGe(60-y) ternary solid solutions determined by differential scanning calorimetry. A second order transition has been characterised for alloys ranging from Ru40Ge60 to Ru40Si10Ge50 at temperatures ranging from 850 to 1040 K, respectively. Tie lines have been established at 1000-900-800-700-600 degrees C by electron microprobe measurements on annealed alloys of the two phase domains: Ru50SixGe(50-x)-Ru40SiyGe(60-y) and Ru40SiyGe(60-y)-SizGe(100-z).

Use of GPS for Photogrammetry, HR-342, 1993

Five test flights were conducted to study the use of Global Positioning System (GPS) in Photogrammetry, three in Iowa, one each in California and Texas. These tests show that GPS can be used to establish ground control by the static method and to determine camera location by the kinematic method. In block triangulation, six GPS controls are required and additional elevation control along the centerline is also required in strip triangulation. The camera location determined by aerial triangulation depends on the scale of the photography. The 1:3000 scale photography showed that the absolute accuracy of the camera location by GPS is better than five centimeters. The 1:40000 scale photography showed that the relative accuracy of the camera location by GPS is about one millimeter. In a strip triangulation elevation control is required in addition to the camera location by GPS. However, for block triangulation camera location by GPS is sufficient. Pre-targeting of pass and tie points gives the best results in both block and strip triangulation. In normal mapping for earth work computations the use of 1:6000 scale photography with GPS control instead of 1:3000 scale is recommended. It is recommended that research be done in the use of GPS for navigation in aerial photographic missions. It is highly recommended that research be done in the use of GPS to determine tip and tilt of the aerial camera, that is required in stereoplotting.

Performance of Various Thicknesses of P.C. Concrete Secondary Pavement, HR-9, 1979

In 1951 Greene County and the Iowa Highway Research Board paved County Road E-33 from Iowa Highway No. 17 (now Iowa 4) to Farlin with various thicknesses [ranging from 4.5 in. (11.4 cm) to 6 in. (15.2 cm)] of portland cement concrete pavement. The project, designated HR-9, was divided into ten research sections. This formed pavement was placed on the existing grade. Eight of the sections were non-reinforced except for centerline tie bars and no contraction joints were used. Mesh reinforcing and contraction joints spaced at 29 ft 7 in. (9.02 m) intervals were used in two 4.5-in. (11.4-cm) thick sections. The concrete in one of the sections was air entrained. Signs denoting the design and limits of the research sections were placed along the roadway. The pavement has performed well over its 28-year life, carrying a light volume of traffic safely while requiring no major maintenance. The 4.5-in. (11.4-cm) thick mesh-reinforced pavement with contraction joints has exhibited the best overall performance.

Wien, Cambridge, Königsberg: filosofisia tapahtumia 1929-1930

Kirjoittaja on Oulun yliopiston aatehistorian professori. Kirjoittajalta on aiemmin julkaistu Tieteessä tapahtuu -lehdessä Wienin piiriä sivuavat artikkelit "Eino Kaila ja tie Wienin piiriin" (TT 2/ 2002), "Kaila ja kahden tunnistamistavan ero" (TT 4/2002), "Realisti Wienin piirin väittelyissä" (TT 7/2002) ja "Positivismin kriitikosta positivistiksi"(TT 8/2002).

Weeds in spring cereal fields in Finland - a third survey

Selostus: Kolmas kevätviljapeltojen rikkakasvikartoitus

Performance of Various Thicknesses of Portland Cement Concrete, HR-9, 30 Year Report, 1981

If adequately designed and high quality material and good construction practices are used, portland cement concrete is very durable. This is demonstrated by the oldest pavement in Iowa (second oldest in the U.S.) paved in 1904, which performed well for 70 years without resurfacing. The design thickness is an important factor in both the performance and cost of pavement. The objective of this paper is to provide a 30-year performance evaluation of a pavement constructed to determine the required design thickness for low volume secondary roadways. In 1951 Greene County and the Iowa Highway Research Board of the Iowa Department of Transportation initiated a four-mile (6.4 km) demonstration project to evaluate thicknesses ranging from 4-1/2" (11.4 cm) to 6" (15.2 cm). The project, consisting of 10 research sections, was formed pavement placed on a gravel roadbed with very little preparation except for redistribution of the loose aggregate. Eight sections were non-reinforced except for centerline tie bars and no contraction joints were used. Mesh reinforcing and contraction joints spaced at 29' 7" (9.02 m) intervals were used in two 4-1/2" (11.4 cm) thick sections. The only air entrained section was non-reinforced. The pavement performed well over its 30-year life carrying a light volume of traffic and did not require major maintenance. There was substantial cracking with average slab length varying directly with thickness. The 4-1/2" (11.4 cm) thick non-air entrained, mesh-reinforced pavement with contraction joints has performed the best.