Search results for "SAF"

Questions on terrorism

1980

DOUBLE EARTH FAULT EFFECTS IN PRESENCE OF INTERCONNECTED EARTH ELECTRODES

2009

The paper presents a study on the effects of double earth faults in Medium Voltage (MV) networks, in presence of electrical interconnection of the earthing systems of the secondary substations. In urban areas, indeed, the earth electrodes of the secondary substations are interconnected and, in many cases, they are also connected to the earth electrodes of the primary stations, in order to realize quasi-equipotential surfaces, intrinsically safe against electric shocks, named Global Earthing Systems (GES). The concept of GES has been introduced in the technical literature ten years ago in the Document HD 637 S1 by CENELEC, with the aim of providing a solution to the problems of designing and…

The Quest for Global Safety

2007

The authors present a systematic study on the factors that have influence on the establishment of the safety conditions ensuring the rise of Global Earthing Systems. Starting from the definition of Global Earthing System given by CENELEC Document HD 637 SI and from the results of the studies done on the last years on the interconnected earthing systems inside MV networks, the paper proposes some directions of deepening on the topic of Global Safety. Some of the themes whom the paper deals with are: the correct definition of proximity, interconnection and quasi-equipotentiality of the earth electrodes belonging to a Global Earthing System; the influence of the presence of HV/MV stations on h…

Introduction: the unusualness and contribution of life span longitudinal studies of aggressive and criminal behavior

2009

Plastic load capacity and stability of frames in fire

1997

The behaviour of real construction materials in different predictable conditions is so complex that it is difficult to describe it precisely in terms of mathematical equations. The problem of the mathematical modelling of materials is, therefore, to be solved rationally by taking into consideration the material type, construction method, load value and external conditions (e.g. temperature). In ambient temperatures there is an interaction of elastic form and plastic form of steelwork failure. This interaction is described by the Merchant-Rankine formula. An analogous interaction should be expected at elevated temperatures. This paper puts forward an interaction formula for elasto-plastic cr…

Low self-control as a precursor to crime and accidents in a Finnish longitudinal study

1995

A Multi-Objective Approach to Optimize a Periodic Maintenance Policy

2012

The present paper proposes a multi-objective approach to find out an optimal periodic maintenance policy for a repairable and stochastically deteriorating multi-component system over a finite time horizon. The tackled problem concerns the determination of the system elements to replace at each scheduled and periodical system inspection by ensuring the simultaneous minimization of both the expected total maintenance cost and the expected global system unavailability time. It is assumed that in the case of system elements failure they are instantaneously detected and repaired by means of minimal repair actions in order to rapidly restore the system. A nonlinear integer mathematical programmi…

ECONOMIC-STATISTICAL DESIGN APPROACH FOR A VSSI X-BAR CHART CONSIDERING TAGUCHI LOSS FUNCTION AND RANDOM PROCESS SHIFTS

2014

Economic design approaches of control charts are commonly based on the assumption that various cost parameters values and the occurrence risk of assignable causes have to be a priori known with precision. However, in real operative contexts, such parameters can be really difficult to accurately estimate, especially considering costs arising from out-of-control conditions of the process. As consequence, pure economic design approaches can involve chart schemes with low statistical performance. To overcome such limitation, it is herein proposed a multi-objective economic-statistical design approach for an adaptive X-bar chart. In particular, such approach aims at the minimization of both the…

A new and simplified approach to assess the pavement surface micro- and macrotexture

2017

Abstract Road safety depends on pavement skid resistance and surface texture. Skid resistance mainly depends on micro-texture and macrotexture. Skid and texture measurements on samples, in the laboratory, at the preliminary stage of the design, would enhance the design in terms of timing, costs, and reliability. Consequently, this study aims at setting up and validating simple methods for assessing surface texture and skid resistance based on core/sample measurements. Experiments were carried out and predictive relationships were set up to explain and predict results. Under given conditions, miniaturised macro-and microtexture tests (modified EN 13036-1 and modified EN 13036-4, respectively…

Risk Assessment of a compound feed process based on HAZOP analysis and linguistic terms

2016

[EN] The size and complexity of industrial plants, along with the characteristics of the products used, require a study, analysis and control of the existing risks in every industrial process. In this paper, a methodology for risk assessment in industrial plants, based on the combination of risks identification through the Hazard and Operability (HAZOP) analysis and the risks evaluation through linguistic variables and fuzzy numbers is applied to a case study consisting on a compound feed plant located in the town of Silla (Valencia, Spain). The results from this study show that the main risk in the compound feed production process is the formation of explosive atmospheres (ATEX). Therefore…