Search results for " compaction"

Early response ofQuercus roburseedlings to soil compaction following germination

2018

Logging operations using heavy machinery effect changes in soil characteristics due to compaction; such conditions can negatively influence seedling development. In stands managed on the basis of close-to-nature silviculture or continuous cover forestry, successful establishment of natural regeneration after logging is important to ensure the proper functioning of a forest ecosystem, to promote soil recovery, and to prevent and mitigate land degradation processes (such as soil erosion, mudflow, waterlogging, and landslides) related to soil compaction and rutting. This work aimed to assess the early response of Quercus robur seedlings to soil compaction during the first 1.5 months after germ…

Procedure for a Temperature-Traffic Model on Rubberized Asphalt Layers for Roads and Railways

2017

The impact of temperature on the mechanical properties and thermal susceptibility of the railway bituminous sub-ballast layer, has served as motivation to develop the advanced measurement of thermal cycles in this layer and, an evaluation of the average seasonal temperatures interpolated by sinusoidal functions, of which characteristic parameters are determined. According to weather situation, Barber’s temperature model was used to prove the effectiveness for the railway superstructure. It is included the assessment of improved modified asphalt mixes performed with coarse rubber from scrap tires, having 1.5 to 3 percent of crumb rubber (particle size 0.2-4 mm) by weight of the total mix, as…

Beam matching with space charge in energy recovery linacs

2019

Abstract Matching with space charge of an Energy-Recovery Linac (ERL) arc into the subsequent RF structure is essential to preserve beam quality. We show how to match beam envelopes and dispersion along the bends and recirculation arcs of an ERL, including space charge forces, in order to adjust the beam to the parameters of the subsequent RF structure. For a qualitative analysis, we show that one can use a beam matrix approach together with the smooth focusing approximation but with longitudinal–transverse coupling. It is also shown that the space-charge-modified dispersion plays a key role for the adjustment of the momentum compaction R 56 required for both the isochronous and the non-iso…

Lossless coding of hyperspectral images with principal polynomial analysis

2014

The transform in image coding aims to remove redundancy among data coefficients so that they can be independently coded, and to capture most of the image information in few coefficients. While the second goal ensures that discarding coefficients will not lead to large errors, the first goal ensures that simple (point-wise) coding schemes can be applied to the retained coefficients with optimal results. Principal Component Analysis (PCA) provides the best independence and data compaction for Gaussian sources. Yet, non-linear generalizations of PCA may provide better performance for more realistic non-Gaussian sources. Principal Polynomial Analysis (PPA) generalizes PCA by removing the non-li…

SURFACE AND MECHANISTIC PROPERTIES OF RECYCLED BITUMINOUS MIXTURES

2019

EXECUTIVE SUMMARY Problem Often, when the characteristics of a bituminous mixture are analised, there are major differences between in-lab and in-situ results. This is due to the fact that the procedures and techniques implemented during the design phase (in lab) may be different from those used on site. Then, is very important to be able to predict the main properties of a mixture particularly when innovative materials are used. For example, when crumb rubber is used, phisical and volumetric properties of mixes may change over time, in particular due to the swelling phenomenon that it alters different properties of the mixture (e.g., viscosity). This study aims to investigate the main aspe…

Ventricular dysfunction and number of non compacted segments in non compaction: Non-independent predictors.

2010

Abstract Background Isolated ventricular noncompaction (IVNC) is characterized by multiple prominent trabeculations and deep intertrabecular recesses. Some reports prove that the chronic heart failure may occur in approximately half of the patients. In this report we investigate the correlation between the number of non compacted segments and entity of systolic dysfunction from the registry and subregistries of the SIEC. Method To identify the correlation between ventricular dysfunction and number of segments involved in non compaction we evaluated a consecutive series of 238 patients affected by non compaction, from the SIEC (Societa Italiana di Ecografia Cardiovascolare) registry. The ave…

CHARACTERIZATION OF RUBBERIZED ASPHALT FOR RAILWAY SUB-BALLASTS

Tesi di dottorato sotto la supervisione del professore Gaetano di Mino del Dipartimento di Ingegneria Civile di Palermo), come borsista Marie-Curie all'interno del progetto SUPRITN 2013/2017. Il mio lavoro e la linea della ricerca riguarda i conglomerati bituminosi con granulato di gomma per lo strato di sub-ballast nelle linee ferroviarie. L’attività di ricerca comprende il mix-design dell’asfalto con aggiunta di gomma, la caratterizzazione e le prestazioni per la ferrovia in termini di comportamento meccanico e lo smorzamento delle vibrazioni. In particolare con l’avvento dell’alta velocità, diversi studi hanno evidenziato ottime caratteristiche fisico-meccaniche per ciò che riguarda il c…

Comparison between a Uniaxial Compaction Tester and a Shear Tester for the Characterization of Powder Flowability

2014

The complete characterization of powder flow properties with shear cells is a long and time-consuming process that requires specially trained operators or costly automated instruments. For these reasons, in industrial practice, the use of simpler and less extensive measurement by uniaxial compaction testers is often preferred. However, previous studies in the literature indicate that the results of the two techniques are not directly comparable due to the different stress state conditions achieved in the two testers.In this study, an experimental campaign to measure the flow function of five different powders with a ring shear tester (RST) and a uniaxial compaction tester (UCT) was performe…

Sealing ability of lateral compaction and tapered single cone gutta-percha techniques in root canals prepared with stainless steel and rotary nickel …

2011

Objectives: The aim of this study was to evaluate the sealing ability of lateral compaction and tapered single cone gutta-percha techniques in root canals prepared with stainless steel and rotary nickel titanium root canal instruments by fluid filtration method. Study design: The root canals were prepared with stainless steel (SS) and nickel titanium (NiTi) instruments. The canals prepared with SS were obturated with lateral compaction technique using .02 tapered cones and the canals prepared with NiTi instruments were obturated with lateral compaction technique using .02 tapered cones or 06 tapered single cones. The amount of leakage was evaluated by fluid filtration model. The results wer…

Long-term non-sustainable soil erosion rates and soil compaction in drip-irrigated citrus plantation in Eastern Iberian Peninsula.

2021

Abstract Agriculture is known to commonly cause soil degradation. In the Mediterranean, soil erosion is widespread due to the millennia-old farming, and new drip-irrigated plantations on slopes, such as the citrus ones, accelerate the process of soil degradation. Until now, the published data about soil erosion in citrus orchards is based on short-term measurements. Long-term soil erosion measurements are needed to assess the sustainability of drip-irrigated citrus production and to design new strategies to control high soil erosion rates. The objective of this study is to assess long-term soil erosion rates in citrus plantations and report the changes in soil bulk density as indicators of …