Search results for "Liability"
showing 10 items of 1754 documents
Sensorless control of PMSM by a linear neural network: TLS EXIN neuron
2010
Sensorless vector control applied to the Permanent Magnet Synchronous Motors (PMSMs) is a very challenging subject. It permits obtaining high dinamical performance by exploiting increased reliability and also reduced cost. Among the different methodologies proposed in literature, a model based approach has been proposed here. In particular, the space vector equations of the PMSM have been re-elaborated to permit the use of a Least Squares technique. The problem has been then faced-up to with the so-called TLS EXIN neuron, which is a linear neural network able to solve the TLS problem on-line. Simulation tests have been done on both interior mounted and surface mounted machines.
Re-analysis of fatigue data for welded joints using the notch stress approach
2010
Abstract Experimental fatigue data for welded joints have been collected and subjected to re-analysis using the notch stress approach according to IIW recommendations. This leads to an overview regarding the reliability of the approach, based on a large number of results (767 specimens). Evidently, there are some limitations in the approach regarding mild notch joints, such as butt joints, which can be assessed non-conservatively. In order to alleviate this problem, an increased minimum notch factor of Kw ⩾ 2.0 is suggested instead of the current recommendation of Kw ⩾ 1.6. The data for most fillet-welded joints agree quite well with the FAT 225 curve; however a reduction to FAT 200 is sugg…
Using semantics to facilitate data integration of offshore wind farms
2012
Operation and maintenance play an important role in extracting power from the wind, especially, in offshore wind energy where wind farms are located far off the shore and under harsh weather conditions. Improved operation and maintenance is likely to reduce costs as well as hazard exposure of the employees. Implementation of advanced information technology is thus crucial for operating offshore wind farms effectively and efficiently and hence improves operation and maintenance. However, information availability and reliability are key issues for their use in the offshore wind domain. In addition, the semantic of information has not been exploited thoroughly. This paper describes the develop…
Impact of increasing penetration of photovoltaic (PV) systems on distribution feeders
2015
This paper investigates impact of increasing photovoltaic (PV) penetration on distribution feeders. The main focus of this work is on ‘how PV systems penetration can influence operation of the protective devices in the distribution feeder?’. PV systems' impact, in a distribution feeder, for 3Φ fault has been analyzed. It considers fault location and protective devices (PDs) settings (e.g. time of PDs operation before a fault gets cleared by it). This paper is also emphasizing on ‘how the penetration of PV can affect voltage quality / unbalance in the distribution feeder’. The considered distribution feeders are supplying residential network and therefore loading on different phases are goin…
Error and Uncertainty Analysis of Non-Uniform Residual Stress Evaluation by Using the Ring-Core Method
2016
Like other mechanical methods used for the residual stress evaluation on a generic structural component, the Ring-Core Method (RCM) is potentially subjected to various error sources that in some particular experimental conditions can lead to significant errors and/or uncertainties on the computed residual stresses. The accuracy of the residual stresses computed by the RCM can be improved by a proper error analysis that allows the user to correct the systematic errors, as well as to evaluate the remaining stress uncertainty due to the random errors. Therefore, in order to give a contribution to the accuracy of the RCM, in the present work the list of the main error sources is presented and t…
A RELIABILITY MODEL FOR OPTIMAL ALLOCATION OF SPARE TOOLS IN FMS
1989
ABSTRACT A model for the dynamic management of the tool set of an FMS workstation is developed. The proposed approach processing the on-line recorded tool failure data updates the estimate of the parameters of the probability density functions of tool life and selects, at the occurence of each failure, the code of the tool to be allocated in the workstation storage devices in order to maximize its reliability over a planned horizon.
Frequency mapping in dynamic light emission with wavelet transform
2013
International audience; Dynamic photon emission microscopy is an e cient tool to analyse today's integrated circuit. Nevertheless, the reduction of transistor's dimensions leads to more complex acquisitions where many spots can be seen. A frequency characterization of the whole acquired area can help to have a better understanding of it. With that purpose in mind, a new methodology to draw frequency mapping of dynamic light emission acquisition is reported. It is fully automated and based on wavelet transform and autocorrelation function. Regarding the possible use in an industrial context, the suggested method can help to localize abnormal emission activity and it gives some perspectives o…
Load management for voltage security using probabilistic fuzzy decision tree method
2016
During contingency, load management is most important in planning, monitoring and controlling of power system. In transmission system, there is limit for controlling the reactive power in large size power network. In order to manage heavy loading on transmission, load management is necessary to avoid voltage collapse. This paper presents a methodology for load management considering voltage security assessment using probabilistic fuzzy decision tree (PFDT) technique. By using probabilistic fuzzy decision tree method, the load management is calculated in optimal manner in real time and insecure operating conditions are observed. With the help of this method, a real time load management plan …
Risk Based Inspection Planning for Fatigue Damage in Offshore Steel Structures
2015
High fatigue reliability is one of the most important design criteria for welded offshore steel structures. Due to repeated wave loading fatigue cracks may initiate and grow in welded joints that are important for the integrity of these structures. The present paper presents the methodology and the practical calculations for risk based inspection planning for fatigue cracks in welded details. Due to the uncertainty in the variables involved in the problem the planning has to be carried out by stochastic modeling and risk based assessments. Scatter in potential crack growth has to be analyzed by applied probabilistic facture mechanics and the uncertainty in the performance of the actual insp…
A Comparative Analysis of the Reliability of Simple and Two-Level Checkpointing Techniques in two Different Distributed Industrial Control System Arc…
2003
In Distributed industrial control systems it is necessary to guarantee certain reliability level. In this sense, Checkpointing and Rollback techniques offer interesting possibilities to achieve fault tolerance without appreciable cost and complexity increment. Several Checkpointing techniques have been proposed. Most of them suppose the presence of stable storage in the system. But distributed industrial control systems usually do not dispose of this kind of storage. So, another storage strategy has to be employed. If Checkpoints were locally stored (Simple Checkpointing), the system tolerates only transient faults. If Checkpoints were locally, at the same node, and, additionally, at anothe…