Search results for "FOREST"

Assessing flow resistance in gravel bed channels by dimensional analysis and self-similarity

2018

Abstract In this paper a new flow resistance equation for open channel flow, based on the integration of a power velocity profile, was tested for gravel bed channels. First this flow resistance equation, theoretically deduced by dimensional analysis and incomplete self-similarity condition, was reported. Then a relationship between the Γ function of the velocity profile, the channel slope and the Froude number was calibrated by the available laboratory measurements of flow velocity, water depth and bed slope carried out in 416 flume experimental runs with a gravel bed. Then the relationship for estimating Γ function and the theoretical resistance equation was tested by 83 independent flume …

Evaluating the Effects of Sediment Transport on Pipe Flow Resistance

2021

In this paper, the applicability of a theoretical flow resistance law to sediment-laden flow in pipes is tested. At first, the incomplete self-similarity (ISS) theory is applied to deduce the velocity profile and the corresponding flow resistance law. Then the available database of measurements carried out by clear water and sediment-laden flows with sediments having a quasi-uniform sediment size and three different values of the mean particle diameter Dm (0.88 mm, 0.41 mm and 0.30 mm) are used to calibrate the Γ parameter of the power-velocity profile. The fitting of the measured local velocity to the power distribution demonstrates that (i) for clear flow the exponent δ can be estimated b…

New Theoretical Solution of Stage-Discharge Relationship for Slit Weirs

2018

In this paper, the flow-process of a slit weir was analyzed on the basis of a theorem of dimensional analysis and incomplete selfsimilarity theory. The theoretically deduced stage-discharge formula then was calibrated using experimental data obtained for a ratio between the weir and the channel width, ranging from 0.05 to 0.25. The deduced stage-discharge relationship allowed measuring discharge values characterized by errors that, for 98% of the measured values, were less than or equal to 5%. The performance of the proposed theoreticalstage-discharge formula also was improved by introducing the Reynolds number (for 98.5% of the measured values the error was less than or equal to 5%, and th…

Testing a theoretically-based overland flow resistance law by Emmett’s database

2021

Abstract The main aim of this paper was to test a recently theoretically deduced flow resistance equation, based on a power-velocity profile, using a wide database of available measurements carried out in laboratory and field experimental runs with overland flow under simulated rainfall. In comparison with previous calibrations and validations of this theoretically deduced flow resistance equation, the used database by Emmett is characterized by a wide range of rainfall intensities (from 79.2 to 303.5 mm h−1 for laboratory runs and from 178.3 to 215.9 mm h−1 for field investigations) and bed slopes (from 0.33 to 17% for laboratory runs and from 2.9 to 33.2% for field investigations). For th…

Gestione dei nitrati in agricoltura

2010

Highly irregular graphs with extreme numbers of edges

1997

Abstract A simple connected graph is highly irregular if each of its vertices is adjacent only to vertices with distinct degrees. In this paper we find: (1) the greatest number of edges of a highly irregular graph with n vertices, where n is an odd integer (for n even this number is given in [1]), (2) the smallest number of edges of a highly irregular graph of given order.

Validation of a mechanistic model for predicting fruit scab infection on different loquat cultivars

2017

[EN] Scab, caused by Fusicladium eriobotryae, is the main disease affecting loquat (Eriobotrya japonica) in the Mediterranean basin. A mechanistic epidemiological model developed in Spain to predict infection of loquat fruit by conidia was assessed in the main loquat cultivated area of Italy (Sicily). A 3-year study (2014-2016) was carried out in an experimental orchard on three loquat cultivars: Algerie, Peluche and San Filipparo. For each cultivar, output of the model was compared with observed scab development on fruits. The scab epidemics observed were different in different years and cultivars, representing a suitable data set for model validation. The model correctly predicted loquat …

A NEW SPECIES OF DISSOCHAETA BLUME (MELASTOMATACEAE) FROM KALIMANTAN (BORNEO, INDONESIA)

2006

Dissochaeta atrobrunnea (Melastomataceae–Dissochaeteae) from Kalimantan (Borneo, Indonesia) is described and illustrated. The species can be assigned to Dissochaeta sect. Dissochaeta and is easily recognized by its dense cover of light brown, sessile, stellate hairs and dark brown, 4–6 mm long bristles on branches, leaf undersurfaces, petioles, inflorescences, bracts and hypanthia. Like all other species of Dissochaeta sect. Dissochaeta, D. atrobrunnea shows heterantherous flowers.

Influenza della tecnica di misura della distribuzione granulometrica sulla stima della curva di ritenzione idrica del suolo

2011

Le distribuzioni granulometriche ottenute sia con il tradizionale metodo per stacciatura-sedimentazione (SH) che con il metodo della diffrattometria laser (LD) sono state utilizzate per determinare le curve di ritenzione idrica di 40 suoli siciliani attraverso modello di Arya e Paris (AP). La curve di ritenzione idrica determinate con il metodo SH sono risultate più accurate di quelle ottenute dal metodo LD. Fra le differenti procedure applicative utilizzate, i risultati migliori si sono ottenuti utilizzando per ciascun suolo un valore del parametro  determinato attraverso una procedura di ottimizzazione. Infine, è stata proposta una relazione tra il parametro  e il contenuto in argilla c…

Effects of Canopy Gap Disturbance on Forest Birds in Boreal Forests

2013

We studied the effects of small-scale disturbance on breeding, forest passerine birds in an old-growth and managed boreal forests in northern Finland. Small-scale disturbance (< 2 ha) in an old-growth and managed forests originated from wind falls and small clear cuts. Continuous forest without gaps was used as a control for both management types (old-growth and managed forests). Passerines' response to disturbance was examined by estimating species richness and abundance of different ecological groups. Species richness and the total abundance of birds did not differ between gap and non-gap plots, neither did the abundance of most ecological groups. Management type or study year were the mo…