Search results for "Reliability"
showing 10 items of 1563 documents
Voltage Rise Issues and Mitigation Techniques Due to High PV Penetration into the Distribution Network
2018
Integration of photovoltaic systems (PV)into the low voltage (LV)grid is seen as a viable and globally accepted optionto meet the ever-increasing energy demands. However, the high PV penetration into the LV distribution grid has raised up many concerns for various stakeholders e.g. distribution company, industry partners, end users etc. The suddenchanges in the voltage level, is one of the main issues due to the reverse power flowfrom distributed energy sources to the grid, has significantly affected the behavior of the traditional LV grid. This paper has reviewed the impacts on voltage profile due to high PV penetration and different techniques used for mitigation these issues such as acti…
Krill herd algorithm-based neural network in structural seismic reliability evaluation
2018
ABSTRACTIn this research work, the relative displacement of the stories has been determined by means of a feedforward Artificial Neural Network (ANN) model, which employs one of the novel methods for the optimization of the artificial neural network weights, namely the krill herd algorithm. For the purpose of this work, the area, elasticity, and load parameters were the input parameters and the relative displacement of the stories was the output parameter. To assess the precision of the feedforward (FF) model optimized using the Krill Herd Optimization (FF-KH) algorithm, comparison of results has been performed relative to the results obtained by the linear regression model, the Genetic Alg…
Faults identification, location and characterization in electrical systems using an analytical model-based approach
2005
The start of the electrical energy market has encouraged distributors to make new investments at distribution level so as to attain higher quality levels. The service continuity is one of the aspects of greater importance in the definition of the quality of the electrical energy. For this reason, the research in the field of fault diagnostic for distribution systems is spreading ever more. This paper presents a novel methodology to identify, locate and characterize the faulty events in the electrical distribution systems. The methodology can be extended to all types of faulty events and is applicable to reconfigurable systems. After having described the guidelines of the methodology, the Au…
Identification of differential risk hotspots for collision and vehicle type in a directed linear network
2019
Traffic accidents can take place in very different ways and involve a substantially distinct number and types of vehicles. Thus, it is of interest to know which parts of a road structure present an overrepresentation of a specific type of traffic accident, specially for some typologies of collisions and vehicles that tend to trigger more severe consequences for the users being involved. In this study, a spatial approach is followed to estimate the risk that different types of collisions and vehicles present in the central area of Valencia (Spain), considering the accidents observed in this city during the period 2014-2017. A directed spatial linear network representing the non-pedestrian ro…
Fault Injection into VHDL Models: Experimental Validation of a Fault-Tolerant Microcomputer System
1999
This work presents a campaign of fault injection to validate the dependability of a fault tolerant microcomputer system. The system is duplex with cold stand-by sparing, parity detection and a watchdog timer. The faults have been injected on a chip-level VHDL model, using an injection tool designed with this purpose. We have carried out a set of injection experiments (with 3000 injections each), injecting transient and permanent faults of types stuck-at, open-line and indetermination on both the signals and variables of the system, running a workload. We have analysed the pathology of the propagated errors, measured their latency, and calculated both detection and recovery coverage. We have…
Reducing False Node Failure Predictions in HPC
2019
Future HPC applications must be able to scale to thousands of compute nodes, while running for several days. The increased runtime and node count inconveniently raises the probability of hardware failures that may interrupt computations. Scientists must therefore protect their simulations against hardware failures. This is typically done using frequent checkpoint& restart, which may have significant overheads. Consequently, the frequency in which checkpoints are taken should be minimized. Predicting hardware failures ahead of time is a promising approach to address this problem, but has remaining issues like false alarms at large scales. In this paper, we introduce the probability of unnece…
Error mitigation using RaptorQ codes in an experimental indoor free space optical link under the influence of turbulence
2015
In free space optical (FSO) communications, several factors can strongly affect the link quality. Among them, one of the most important impairments that can degrade the FSO link quality and its reliability even under the clear sky conditions consists of optical turbulence. In this work, the authors investigate the generation of both weak and moderate turbulence regimes in an indoor environment to assess the FSO link quality. In particular, they show that, due to the presence of the turbulence, the link experiences both erasure errors and packet losses during transmission, and also compare the experimental statistical distribution of samples with the predicted Gamma Gamma model. Furthermore,…
Energy Conscious Building Design
1987
Since the beginning of energy crisis many design tools have been developed in order to enable the designer to cope with energy consumption in buildings. These tools are of different kind: from very sophisticated simulation models to simplified (often too much) methods. Each of them offers various advantages and disadvantages, and it is up to the designer to choose among them.
Sleep assessment devices: types, market analysis, and a critical view on accuracy and validation
2019
[EN] Introduction: Sleep assessment devices are essential for the detection, diagnosis, and monitoring of sleep disorders. This paper provides a state-of-the-art review and comparison of sleep assessment devices and a market analysis. Areas covered: Hardware devices are classified into contact and contactless devices. For each group, the underlying technologies are presented, paying special attention to their limitations. A systematic literature review has been carried out by comparing the most important validation studies of sleep tracking devices in terms of sensitivity and specificity. A market analysis has also been carried out in order to list the most used, best-selling, and most high…
The Effect of Process Evolution on Capability Study
1996
In today manufacturing scenario the trend to produce with lower and lower tolerance and continuously decrease the defectives rate seems to be irreversible. Then the evaluation of system performances is essential to determine if the process is able to respect our tolerances. With the classical approach this evaluation is realised by considering the process in the in control state and evaluating the capability indices and, consequently, the defectives rate. In this paper the evolution of the process is considered in terms of the mean out-of-control-time, and the real defective rate is evaluated by proposing a new capability index.