Search results for " Reliability."
showing 10 items of 551 documents
Simplified Model of PC Concrete Beams with Corroded Strands in Highway Viaduct: Case Study and Analytical Modeling
2021
AbstractIn this paper, several cases of failure of prestressed reinforced concrete (PC) beams of a viaduct in Italy due to cable corrosion are presented. Therefore, a simplified model to determine ...
A PCA-based clustering algorithm for the identification of stratiform and convective precipitation at the event scale: an application to the sub-hour…
2021
AbstractUnderstanding the structure of precipitation and its separation into stratiform and convective components is still today one of the important and interesting challenges for the scientific community. Despite this interest and the advances made in this field, the classification of rainfall into convective and stratiform components is still today not trivial. This study applies a novel criterion based on a clustering approach to analyze a high temporal resolution precipitation dataset collected for the period 2002–2018 over the Sicily (Italy). Starting from the rainfall events obtained from this dataset, the developed methodology makes it possible to classify the rainfall events into f…
Statement validity assessment: Inter-rater reliability of criteria-based content analysis in the mock-crime paradigm
2005
Methods. Three raters were trained in CBCA. Subsequently, they analysed transcripts of 102 statements referring to a simulated theft of money. Some of the statements were based on experience and some were confabulated. The raters used 4-point scales, respectively, to judge the degree to which 18 of the 19 CBCA criteria were fulfilled in each statement. Results. The analysis of rater judgment distributions revealed that, with judgments of individual raters varying only slightly across transcripts, the weighted kappa coefficient, the product-moment correlation, and the intra-class correlation were inadequate indices of reliability. The Finn-coefficient and percentage agreement, which were cal…
Degraded Gerber Saddles in RC Bridges
2023
Sudden failure of reinforced concrete (RC) or prestressed concrete (PC) Gerber saddles of bridges and viaducts has occurred all around in the word in the last few years due to corrosion of steel bars. The danger of sudden and brittle failure is often due to general and pitting corrosion of steel bars, concrete crushing, and loss of bond in steel bars. In this paper, the flexural response of reinforced concrete Gerber supports under their self-weight with or without service loads was investigated through determination of the load-deflection response of beams, with the focus on the consequences of pitting corrosion and loss of bond in steel bars. A simplified strut-and-tie model was developed…
Tracing the Cultural Background of Lone-Wolf Terrorism
2021
The end of the Cold War, as well as the collapse of the Soviet Union, posed new greater challenges and risks for the “Global North.” Terrorism—doubtless—seems to be one of them. Over the recent years, and particularly after 9/11, terrorists changed the focus of their attacks. While classic terrorism targeted important persons such as politicians, chief police officers, or celebrities, modern terrorism planned attacks on leisure-spots spaces, tourist destinations, and lay-persons. This is particularly troublesome for policymakers (who are in charge of orchestrating all-pervading models to preserve homeland security) and for field-workers who are seriously punished when they are in contact wi…
Condition Monitoring Technologies for Synthetic Fiber Ropes - a Review
2020
This paper presents a review of different condition monitoring technologies for fiber ropes. Specifically, it presents an overview of the articles and patents on the subject, ranging from the early 70’s up until today with the state of the art. Experimental results are also included and discussed in a conditionmonitoring context,where failuremechanisms and changes in physical parameters give improved insight into the degradation process of fiber ropes. From this review, it is found that automatic width measurement has received surprisingly little attention, and might be a future direction for the development of a continuous condition monitoring system for synthetic fiber ropes.
Vulnerability of a Damaged Bridge Abutment in a Seismic Area
2018
The case of the abutment of a motorway urban viaduct damaged by human intervention is presented. Built in the 1960s, it lies in a critical seismic area and the human-induced damage involved the elements of the abutment foundation. The structure is geometrically complex and the evaluations of its structural safety were carried out by applying Italian codes from different times: those concerning the time of construction, those of a recent past (1996), and those of the present (2008), inspired by Eurocodes. A comparison between the safety checks performed and the requirements of all these codes is presented and discussed, especially regarding safety coefficients after the damage was done. Two …
Emergent vulnerabilities in Integrated Operations: A proactive simulation study of economic risk
2009
Abstract The protection of critical infrastructure requires an understanding of the effects of change on current and future safety and operations. Vulnerabilities may emerge during the rollout of updated techniques and integration of new technology with existing work practices. Managers need to understand how their decisions, often focused on economic priorities, affect the dynamics of vulnerability over time. Such understanding is difficult to obtain, as the historical data typically used for decision support, prediction and forecasting may not be available. We report on the use of group model building and simulation to consider proactively the effects of a 10-year, multi-billion dollar mo…
A Fuzzy Inference Expert System to Support the Decision of Deploying a Military Naval Unit to a Mission
2009
Naval military units are complex systems required to operate in fixed time frames in offshore tasks where maintenance operations are drastically limited. A failure during a mission is a critical event that can drastically influence the mission success. The decision of switching a unit to a mission hence requires complex judgments involving information about the health status of machineries and the environmental conditions. The present procedure aims to support the decision about switching a unit to a mission considering the vagueness and uncertainty of information by means of fuzzy theory and emulates the decision process of a human expert by means of a rule-based inference engine. A numeri…
On a linear diophantine problem of Frobenius
1993
Abstract In this paper, linear diophantine problem of Frobenius is discussed. A theorem concerning the largest integer g m (a1,a2) and the smallest integer G m (a1,a2) with m different representations with a1,a2 as basis is proved.