Search results for "Compaction"

Global dynamical behaviors in a physical shallow water system

2016

International audience; The theory of bifurcations of dynamical systems is used to investigate the behavior of travelling wave solutions in an entire family of shallow water wave equations. This family is obtained by a perturbative asymptotic expansion for unidirectional shallow water waves. According to the parameters of the system, this family can lead to different sets of known equations such as Camassa-Holm, Korteweg-de Vries, Degasperis and Procesi and several other dispersive equations of the third order. Looking for possible travelling wave solutions, we show that different phase orbits in some regions of parametric planes are similar to those obtained with the model of the pressure …

Prediction of hydraulic and acoustic properties of open-graded mixes

2014

The use of open-graded mixes increases significantly the hydraulic permeability of pavement and contributes to reduce the noise impact in comparison to traditional pavement. Such characteristics are very appealing and would greatly increase driver's safety. However, during service life, the pores tend to be clogged by many factors among them secondary traffic compaction and filling of voids by fine materials are relevant, especially on heavy routes. In this case the noise reduction and drainage capabilities will gradually disappear, causing serious problems for road safety and maintenance. In this paper we propose a simulation approach in order to predict the drainage and acoustic behavior …

Impact Assessment of Skidding Extraction: Effects on Physical and Chemical Properties of Forest Soils and on Maple Seedling Growing along the Skid Tr…

2019

Several studies investigated soil disturbances caused on skid trails by forest logging. However, there is still a lack of knowledge about the severity and the distance of disturbances along both sides from the trails. The aims of this study were: i) to investigate the changes in physical and chemical properties of soil along the sides of skidding trails

Isolated left ventricular non-compaction: A larger part of submerged iceberg with criteria for diagnosis to the limits of standard

2010

An unusual cause of cerebral cardioembolism in a 33-year-old man due to ventricular noncompaction

2009

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Performance-based characterization of recycled polymer modified asphalt mixture

2021

Due to the introduction of secondary materials, the asphalt mixtures to be designed and tested in our laboratories are constantly becoming much more complex than traditional asphalt mixtures making difficult to use conventional laboratory procedure and/or predict expected results. This study proposes a comprehensive characterization of asphalt mixture modified with recycled polymer compound by using both wet and dry process proposing adjustments to laboratory mixing and sample compaction procedure. Accordingly, three AC20 Hot Asphalt Mixture (HMA) were designed and their conventional and performance related properties were assessed by looking at a) Indirect Tensile test (ITS) a) moisture da…

An investigation on using pre-treated tyre rubber as a replacement of synthetic polymers for bitumen modification

2015

Rubberized bitumen obtained through a swelling process, has widely proven to be a successful technology for asphalt pavement applications and a solution to reduce the dismantling of tyre rubber on landfills. However, this technology presents two main operative issues which needs the adoption of costly special equipment. Firstly, significant high value of High Temperature Viscosity (HTV) which imposes mixing and compaction difficulties and leads to increased energy consumption and emissions. Furthermore, during the hot storage period, phase separation between rubber particles and the base bitumen could occur. Developing Recycled Tyre Rubber Modified Bitumen (RTR-MBs) with improved storage st…

APPLICAZIONE DI UN PROTOTIPO DI MOTOVANGATRICE PER PRESERVARE LA FERTILITÀ DEL SUOLO

Negli ambienti caratterizzati da forti pendenze o sistemati a terrazze, nell’ambito delle lavorazioni superficiali, viene impiegato diffusamente il motocoltivatore provvisto di zappatrice rotativa. Tuttavia, l’effetto dell’uso ripetuto della zappatrice per lavorazione del terreno ha una notevole influenza sulle caratteristiche del terreno, che si presenta finemente polverizzato, soffice e astrutturato. Al fine di limitare tali inconvenienti, è stata progettata dalla sezione Meccanica del Dipartimento Scienze Agrarie e Forestali dell’Università di Palermo, in collaborazione con la ditta costruttrice Agrotec di Padova, una macchina innovativa semovente provvista di organi di lavoro del tipo a…

Have tractor manufacturers bore in mind soil compaction over the last 40 years?

2019

Soil compaction is the compression of soil particles in a lower volume as a consequence of the reduction of the spaces existing among the particles themselves. This phenomenon is caused by natural forces and, above all, human ones. In order to estimate the field damages that can be caused by the traffic of agricultural machines, the load and the mean pressure applied by the tyres onto the soil can be measured. The research aim is to determine the pressure applied by each considered tractor onto the soil, in order to evaluate the effect of the traffic of tractors onto the soil itself. A total of 783 wheeled tractors manufactured and marketed in the last 35 years (1979-2014) was investigated.…

Neuromuscular disorders and non compaction: How much is the strength of the association and how can it be suspected?

2009

In many reports Finsterer and Stöllberger reported a strong association between non compaction of the left ventricle and neuromuscular disorders. In the same report the authors described a neurological involvement in more than 50%. Recently we published our personal experience, about 21 paediatric patients: only 4 patients (19%) showed a neuromuscular disorder, and only 1 of them showed an increased plasmatic level of CK, and in particular of MM isoform, with a normal level of CK-MB. None presented high levels of troponine. Through the experience of 3 centres we collected 61 patients affected by non compaction that performed a neurological control, and only 14 (21%) were affected by neuromu…