ARX Linear Modeling of Hot Mix Asphalt Compaction

The compaction of the asphalt layer is a fundamental operation in pavement construction but, at the same time, its control is very difficult. The consequences on costs, on execution time and on duration of the pavement are very relevant and, for that reason, we wanted to prepare a predictive model able to minimize the attempts, often unsuccessful, which the executor is forced to make in the early stages of the construction. Due to a very large number of variables, we could not control the phenomenon with any known physical models; so, for the purpose of this research paper, we preferred to make use of a so-called black-box linear model, calibrating it with an appropriate procedure of trials and errors.The results achieved with this model have made it possible to predict the value of the material density with a reliability of 88% that, for the number of involved variables, can be considered a satisfactory target.With this procedure and knowing the boundary conditions (characteristics of the roller and the material), it is possible to arrange the compaction very quickly, achieving a good compromise between layer density and execution times

Identification of the most important factors in the compaction process

The compaction of a hot mix asphalt depends on a number of important factors whose control, during the execution of the pavement, is complex; however it is essential to achieve the results envisaged in the design with the least possible cost. Therefore, the evaluation of the effect of these variables on the material density is important as well as their quantification in real time. This research, starting from a survey of some environmental variables, together with the hot mix asphalt density using an electrical impedance device, through the application of a neuro-fuzzy technique, proposes a procedure to classify the most important features. These results can be rapidly deduced during the paving operations; calibrations required to correct the compaction can be applied on site without waiting further time necessary for the extraction of the cores and the subsequent laboratory analysis. In this way it is possible to identify with a better precision the aspects of the environmental context requiring more attention. In addition, the model permits the inclusion of new input variables and additional data that can be recorded in following phases

Evaluation of the laboratory prediction of surface properties of bituminous mixtures. Construction and Building Materials. Volume 23. Issue 2. Elsevier Ltd, Amsterdam. ISSN: 0950-0618 pp. 943–952

An experimental and analytical investigation was carried out both in laboratory and in situ on wearing courses. The approach presented in this paper aims to predict the in situ density and surface properties of bituminous layers, during the phase of mix design in laboratory. Therefore, the main attempt of this study is to identify, amongst the commonly available laboratory equipments, the most adequate for producing specimens that, used for carrying out simple and reliable laboratory test, allow the prediction of the surface characteristics of the mixture as laid on site. This is done by comparing the data collected from an experimental site with those calculated from laboratory specimens compacted with the superpave gyratory compactor (SGC). Typical laboratory tests (such as the sand patch method and the skid test) as well as the surface data obtained with a laser profilometer have been considered for characterizing the properties of a standard Italian wearing course, laid in two different final thicknesses and produced with the most common raw materials, according to the currently used techniques for mixtures production and laying process for maintenance work. An evaluation of the SGC ability to represent the density and surface properties of the mixture once on site is then discussed

Compaction of Open-Graded HMAs Evaluated by Fuzzy Clustering Technique

The aim of this paper is the proposal of an expeditious procedure to be used during the execution of an asphalt layer for improving the compaction task. This procedure, based on a fuzzy clustering technique, starts from the knowledge of some information recorded by ordinary measuring instruments and provides an aid to the decision-maker on the number of roller passes needed to achieve a specic density at a certain temperature. This result can be deduced with great rapidity during the paving operations on site without waiting for the time spent in the core extraction and in the subsequent laboratory analysis. In this way it is possible to identify more precisely which aspects of the execution have to be corrected for performing the best compaction

Preterm birth: incidence, risk factors and second trimester cervical length in a single center population. A two-year retrospective study

To report the incidence and the major risk factors (RFs) associated with preterm birth (PTB), combining both maternal RFs and cervical length (CL), and to understand if cervical length measurement is really useful in all the patients

Implementation of a program for quality assurance on leaf positioning accuracy using Gafchromic ® RTQA2 films

In radiotherapy treatments the correct dose delivery to the target volume and the consequent conservation of healthy tissues is affected by multileaf collimator (MLC) leaf positioning accuracy and reproducibility, mostly in intensity-modulated radiation therapy (IMRT): For this reason a quality assurance (QA) program is necessary to ensure the best treatment possible to each patient. The aim of this study is the implementation of a method using Gafchromic ® RTQA 2 films to perform routine QA on the MLC, both for qualitative and quantitative analysis. A flatbed document scanner (Epson 10000XL) was used in conjunction with radiochromic detector; a scanning protocol was firstly defined to improve readout accuracy. RTQA2 films were irradiated with 6 MV X-rays at different dose levels to obtain calibration curve. To evaluate the leaf positioning accuracy in different conditions, a rhomboidal shape and a field consisting in three rectangular segments were selected. The images quantitative analysis was handled with a program developed in MATLAB to evaluate the differences between expected and measured leaves positions. The reproducibility and global uncertainty of the method were estimated to be equal to 0.5% and 0.6 mm, respectively. Moreover, a qualitative test was performed: A garden picket fence field, consisting in multiple segments 2 × 22 cm 2 , was realized setting known leaves shifts to test the method sensitivity. The picket fence test shows that the method is able to detect displacements equal to 1 mm. The results suggest that Gafchromic ® RTQA2 films represent a reliable tool to perform MLC routine QA

Intestinal tuberculosis in a patient with Cushing’s syndrome

A 39-year-old woman presented with cushingoid features was worked up and diagnosed to have ACTH-independent Cushing’s syndrome. Computed tomography of the whole abdomen revealed a left adrenal mass. She was scheduled for elective laparoscopic left adrenalectomy, however, a few days prior to the surgery, the patient had hematochezia. Colonoscopy revealed multiple ulcers on the terminal ileum, to which biopsy revealed Mycobacterium tuberculosis infection. The patient underwent laparoscopic left adrenalectomy on the same admission, which revealed adrenal adenoma on histopathology