Search results for "Reliability engineering"
showing 10 items of 224 documents
UML-Based Reliability Modeling of Network Services, a UDP Echo Service Case Study
2009
In the paper, we discuss state space reliability modeling formalism of distributed systems and services compliant with UML metamodel. Behavior of modeled application system we describe in terms of states. Service generation process we represent as a sequence of application system states. State space approach allows us to define dependence between application system components via dependence between components states and states input, output parameters. Reliability of application system component we define for each simply action state. Reliability of a service we express by components reliability in states determined by service generation process. As an example, we analyze reliability of cli…
Energy saving in WWTP: Daily benchmarking under uncertainty and data availability limitations
2016
Efficient management of Waste Water Treatment Plants (WWTPs) can produce significant environmental and economic benefits. Energy benchmarking can be used to compare WWTPs, identify targets and use these to improve their performance. Different authors have performed benchmark analysis on monthly or yearly basis but their approaches suffer from a time lag between an event, its detection, interpretation and potential actions. The availability of on-line measurement data on many WWTPs should theoretically enable the decrease of the management response time by daily benchmarking. Unfortunately this approach is often impossible because of limited data availability. This paper proposes a methodolo…
Domestic demand predictions considering influence of external environmental parameters
2015
A precise prediction of domestic demand is very important for establishing home energy management system and preventing the damage caused by overloading. In this work, active and reactive power consumption prediction model based on historical power usage data and external environment parameter data (temperature and solar radiation) is presented for a typical Southern Norwegian house. In the presented model, a neural network is adopted as a main prediction technique and historical domestic load data of around 2 years are utilized for training and testing purpose. Temperature and global irradiation (which illustrates the solar radiation level quantitatively) are employed as external parameter…
Building Automation and Control Systems and Electrical Distribution Grids: A Study on the Effects of Loads Control Logics on Power Losses and Peaks
2018
Growing home comfort is causing increasing energy consumption in residential buildings and a consequent stress in urban medium and low voltage distribution networks. Therefore, distribution system operators are obliged to manage problems related to the reliability of the electricity system and, above all, they must consider investments for enhancing the electrical infrastructure. The purpose of this paper is to assess how the reduction of building electricity consumption and the modification of the building load profile, due to load automation, combined with suitable load control programs, can improve network reliability and distribution efficiency. This paper proposes an extensive study on…
Dynamic reconfiguration systems for PV plant: Technical and economic analysis
2020
Solar plants suffer of partial shading and mismatch problems. Without considering the generation of hot spots and the resulting security issues, a monitoring system for the health of a PV plant should be useful to drive a dynamic reconfiguration system (DRS) to solve bottlenecks due to different panels’ shading. Over the years different DRS architectures have been proposed, but no suggestions about costs and benefits have been provided. Starting from technical subjects such as differences of the topologies driving the hardware complexity and number of components, this paper identifies the cost of DRS and its lifetime, and based on these issues it provides an economic analysis for a 6 kWp PV…
Methodologies for the Exploitation of Existing Energy Corridors. GIS Analysis and DTR Applications
2018
The exploitation of power lines currently in operation has now become a common practice among electric system operators. The construction of new power lines requires taking economic, political and social problems into consideration. This paper considers two methodologies adopted by the Italian Transmission System Operator (TSO), Terna S.p.A.: Dynamic Thermal Rating (DTR) and Laser Imaging Detection and Ranging-Geographic Information System (L-GIS). DTR systems dynamically calculate the real transport capacity of a power line. The L-GIS system allows, after the geo-referencing of the power line, the management of any interference between the line and the nearby obstacles, permitting the opti…
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…
Cost Reduction in Irrigation Networks by an Efficient Use of Pressure Reducing Valves
1992
The cost effective design of hydraulic networks has been traditionally studied from the point of view of the relationship between hydraulic variables and economic parameters, with piping being the main element studied. The reason is clear: the piping is by far the most costly item of a projected network. However it is not usual to find an explicit consideration of the influence that pipe thickness has on the cost of the network because of the added difficulty that this aspect poses to formulating the problem of optimization. In irrigation networks, which are typically branched, it is advisable to place Pressure Reducing Valves (PRV’s) to fulfil three main goals: 1) to control the flow rate …
Using partial-orders for detecting faults in concurrent systems
1998
The paper suggests test derivation approaches to obtain test suites for concurrent systems based on the concept of fault coverage criteria in opposition to structural test coverage criteria. Using a partial-order model, called Mazurkiewicz Trace Machine (MTM), for test derivation, the state explosion problem can be alleviated. The derived test suites are characterized by their small size compared to test suites from traditional test derivation approaches and exhibit a defined degree of fault coverage according to certain fault models. The fault models of concurrent systems considered in the paper are based on the most common faults, acceptance, refusal, and transfer faults. A scenario of te…
Effects of Demand Side Management on the Operation of an Isolated LV Microgrids
2019
The work presents the results of a study regarding the impact of Demand Side Management actions on flexible loads distributed at the domestic end-users' facilities in an isolated low voltage microgrid. Aim of the research study is to evaluate how the implementation of local control actions on the end-user's side can impact on the operation of the isolated microgrid. The Demand Side Management is applied by each domestic user to optimize the operation of its own resources following well-defined operative steps. The study is carried out implementing a suitable model of the microgrid in Neplan environment, while the daily controlled load profiles of the end-users are evaluated using the Montec…