Search results for "Compaction"

High chromium-carbon’s steel microstructural and properties evolutions after Hot Isostatic Pressing (HIP) process : From powder to final product.

2021

Fe-Cr-C alloys are frequently used as hard coating coatings for nuclear valves in pressurized water reactors (PWRs), due to their good mechanical resistance and corrosion. The Norem02 alloy (Fe - 25% Cr - 4% Ni - 4% Mn - 4% Si - 2% Mo) is one of the most promising candidates. Hardfacing coatings are typically deposited by a plasma transferred arc welding (PTAW) process, which results in a coarse and heterogeneous microstructure, exhibiting unsatisfactory wear resistance properties, mainly at high temperature. In the present study, Norem02 is developed by Hot Isostatic Compression (CIC), a pressure assisted sintering technique where a powder is placed in a plastically deformable container un…

Growth pattern of underlithified strata during thrust-related folding

2004

Abstract Asymmetric anticlines with overturned or steeply dipping forelimbs and gently dipping backlimbs are generally interpreted as thrust-related folds. Fold asymmetry occurs as a consequence of forelimb rotation. If deformation takes place in environments dominated by submarine sedimentation, the limbs coincide with the slope (depositional surface) and rotation reflects slope steepening. If folds are nucleated in poorly or unlithified deposits, growth geometry also depends on the properties of the media, such as cohesion and the angle of internal friction. For cohesionless deposits, the tilting of the slope influences the equilibrium of the soft sediments, resulting in gravity-driven fl…

Mapping soil compaction measuring cone penetrometer resistance

2003

The quickest way for monitoring soil compaction differences in a field is measuring cone penetrometer resistance. Soil compaction can be significantly spatially variable, depending on the amount and distribution of the traffic of agricultural machines in the field. Therefore, it could be useful to measure soil compaction on a localised basis, in order to produce maps of the damages caused by the traffic of agricultural machines and/or the action of tillage implements. Aim of this paper is to present a system developed by the Department I.T.A.F. for the geo-referenced measurement of cone penetrometer resistance and for mapping soil compaction. This system was built fitting a minitransporter …

Systems for evaluating the correlation between soil cone penetrometer resistance and shear strength

2008

The aim of this research is to study possible correlations between soil compaction (and related soil cone penetrometer resistance measurements) and shear strength normal to the field plane, required to cut the soil with a subsoiler. A measurement system for sensing the soil cone penetrometer resistance was built mounting, on a frame fixed to the front part of a tractor, a rod and a penetration cone with a load cell. A load cell, mounted on the tractor drawbar, pulling a subsoiler, allowed to measure the shear strength normal to the field plane, required to cut the soil. Both load cells were connected, through a display, to a portable computer, where a software was used for acquiring the dat…

Isolated non-compaction, stroke and trabecular meshwork fibrosis

2009

Left ventricular non compaction: epidemiology, clinical findings, diagnosis and therapy

2014

Abstract Left ventricular non compaction (LVNC) is a cardiomyopathy due to an arrest of the normal development of myocardium which determines the persistence of foetal myocardium in post--natal life in at least 2/3 of the wall (criterion known as non compacted/ compacted ratio greater than 2). Although in absence of a confirmed prevalence of LVNC, reviewing literature shows an increasing number of reports over the years, though diagnosed cases represent just the tip of a realistically far wider phenomenon. Clinical manifestations are variable, ranging from the absence of any symptom to congestive heart failure, arrhythmias and systemic thromboembolism. Echocardiography is the gold standard …

On the hydro-mechanical behaviour of remoulded and natural Opalinus Clay shale

2016

The geo-energy sector makes use of advanced technologies such as shale gas extraction, CO2 sequestration and nuclear waste geological disposal that rely on the exploitation of shale formations. Due to the great depths involved in these applications and the difficulties in retrieving intact samples, remoulded shale specimens are often adopted for hydro-mechanical testing. Remoulded and intact shales may substantially differ in their hydro-mechanical behaviour due to the particular structure of the natural material, which is the result of diagenesis and burial history. This paper presents an experimental campaign aimed at (i) characterizing the role of diagenesis and depth for Opalinus Clay s…

Effects of soil compaction, rain exposure and their interaction on Soil Carbon Dioxide emission

2012

Soils release more carbon per annum than current global anthropogenic emissions (Luo and Zhou, 2006). Soils emit carbon dioxide through mineralization and decomposition of organic matter and respiration of roots and soil organism (Houghton 2007) Evaluation of the effects of abiotic factors on microbial activity is of major importance in the context of mitigation greenhouse gases emissions. One of the key greenhouse gases is carbon dioxide (CO2) and previous studies demonstrate that soil CO2 emission is significantly affected by temperature and soil water content. There are a limited number of studies that examine the impact of bulk density and soil surface characteristics as a result of exp…

Multivariate geostatistics for assessing and predicting soil compaction

2005

The aim of this research is to investigate the potential of geostatistical techniques for understanding and evaluating the spatial variability of soil compaction, caused by the traffic of agricultural machines and/or the action of tillage implements. Soil cone penetrometer resistance was measured in a field of inland Sicily, along a transect of 3 m length, from the soil surface until 70 cm depth. The 3D mean maps showed a random variation on the surface and a high spatial correlation among penetrometer resistance data measured at different depths. The map corresponding to five tractor passes showed the largest extension of the areas characterised by the highest values of penetrometer resist…

Survey of the mean pressure exerted by a wide range of tractors on the soil

2010

In order to predict the mean pressure exerted by a vehicle tyre on the soil, in 1984 Plackett suggested measuring the contact area of a tyre on a hard surface. The model proposed by Hallonborg in 1996, based on the “super ellipse theory”, provided the best results in terms of prediction of the tyre-soil contact area. In this study 82 4WD tractors with different power, mass and age of manufacture were surveyed. Relying on their technical features, the contact area of the front and rear tyres of each tractor and, therefore, their pressure on the soil was calculated, in order to assess the attention paid by manufacturers to soil compaction. The results of this survey showed that the mean press…