Search results for "leakage"
showing 10 items of 146 documents
Performance Comparison of Electrical Motors equipped with slightly Asymmetrical Windings
2019
This paper presents a comparison between the performances of electrical machines equipped with slightly asymmetrical windings. More in detail, by modifying the stator geometry of an Interior Permanent Magnet Synchronous Machine equipped with a symmetrical winding configuration, other two slightly asymmetrical winding topologies are obtained. The three models are, then, analyzed by means of a finite element method (FEM) and the related results are compared in terms of cogging torque, static characteristics and leakage factor. The obtained results demonstrate that the adoption of slightly asymmetrical windings could be an interesting alternative solution during the design stage of electrical …
Leakage-detection in blade pitch control systems for wind turbines
2012
The main contribution of the work is a systematic study evaluating the performance of different filters for leakage detection in pitch control systems. The effectiveness of the proposed methods is examined in a Matlab/Simulink real-time environment. The test bed consists of the following elements: hydraulic power unit, servo valve, two leakage bypasses, hydraulic cylinder, payload and xPC-based control system. The filters are tested with the state-augmentation and the hypothesis testing approaches. To our knowledge, the comparison of these different approaches has not been done previously for this type of application. The paper concludes on the accuracy and sensitivity of the leakage detect…
GA-based Off-Line Parameter Estimation of the Induction Motor Model Including Magnetic Saturation and Iron Losses
2020
This paper, starting from recent papers in the scientific literature dealing with Rotating Induction Motor (RIM) dynamic modelling, as a first step, improves its space-vector dynamic model, including both the magnetic saturation and iron losses; The main original aspects of the proposed model are the following: 1) the magnetic saturation of the iron core has been described on the basis of both current versus flux and flux versus current functions, 3) it includes the iron losses, separating them in hysteresis and eddy current ones, 4) it includes the effect of the load on the magnetic saturation. Afterwards, it proposes an off-line technique for the estimation of electrical parameters of thi…
A PC-based instrument for harmonics and interharmonics measurement in power supply systems
2004
Abstract Growing interest on power quality has led international working groups to define new standards for testing and measurement techniques to apply to power systems. Special attention has been paid to harmonic and interharmonic measurements. Here, the authors introduce a PC-based instrument capable of synchronising sampling frequency with fundamental frequency in order to perform on-line voltage or current distortion analysis. The instrument has been developed in accordance with currently available standards and international documents, IEC 61000-4-7 Ed. 2002, IEC 61000-4-30 Ed. 2003, Draft Guide IEEE P1159.1 Ed. 2003 and limits given by IEC 61000 Part. 3. A detailed description of the …
Estimating the environmental and resource costs of leakage in water distribution systems: A shadow price approach.
2016
Water scarcity is one of the main problems faced by many regions in the XXIst century. In this context, the need to reduce leakages from water distribution systems has gained almost universal acceptance. The concept of sustainable economic level of leakage (SELL) has been proposed to internalize the environmental and resource costs within economic level of leakage calculations. However, because these costs are not set by the market, they have not often been calculated. In this paper, the directional-distance function was used to estimate the shadow price of leakages as a proxy of their environmental and resource costs. This is a pioneering approach to the economic valuation of leakage exter…
Delayed chronic intracranial subdural hematoma complicating resection of a tanycytic thoracic ependymoma
2015
Background To demonstrate that the diagnosis of an intracranial subdural hematoma should be considered for patients presenting with acute or delayed symptoms of intracranial pathology following resection of a spinal tumor. Case description We present a case of a 57-year-old woman found to have a chronic subdural hematoma 1 month following resection of a thoracic extramedullary ependymoma. Evacuation of the hematoma through a burr hole relieved the presenting symptoms and signs. Resolution of the hematoma was confirmed with a computed tomography (CT) scan. Conclusion Headache and other symptoms not referable to spinal pathology should be regarded as a warning sign of an intracranial subdural…
SETUP OF VIRTUAL EXPERIMENTS AND CRITICAL ANALYSIS OF CONVENTIONAL THERMOECONOMIC DIAGNOSIS OF MULTIPLE FAULTS IN AIR-CONDENSED ROOFTOP SYSTEMS
2012
The diagnosis of soft faults in vapor compression cooling systems is a crucial activity, since malfunctions may provoke heavy degradation in plant performance and increase the power consumption for space cooling. Among the various Faults Detection and Diagnosis techniques developed over the last two decades, thermoeconomic diagnosis has been playing only a marginal role due to the difficulties encountered when applying the conventional thermoeconomic approaches to vapor compression refrigeration plants. In this paper a critical analysis on capabilities and limits of thermoeconomic diagnosis of refrigeration systems is proposed. The reference plant assumed for this study is a 116 kWc air-con…
Radiation leakage study for the Valencia applicators
2011
Abstract Introduction and purpose The Valencia applicators which are accessories of the microSelectron-HDR afterloader (Nucletron, Veenendaal, The Netherlands) are designed to treat skin lesions. These cup-shaped applicators are an alternative to superficial/orthovoltage x-ray treatment units. They limit the irradiation to the required area using tungsten-alloy shielding, and are equipped with a tungsten-alloy flattering filter allowing the treatment of skin tumors, the oral cavity, vaginal cuff, etc. The tungsten-alloy thickness to shield radiation is not the same in all parts of the applicators. This fact led us to question whether the leakage radiation differs depending on where it is me…
Fusion of biological membranes
2005
The process of membrane fusion has been examined by Monte Carlo simulation, and is found to be very different than the conventional picture. The differences in mechanism lead to several predictions, in particular that fusion is accompanied by transient leakage. This prediction has recently been verified. Self-consistent field theory is applied to examine the free energy barriers in the different scenarios.
Faut-il réaliser un scanner quand la protéine C réactive est élevée après chirurgie colorectale ? Résultats de la cohorte IMACORS
2017
Resume Introduction Les concentrations seriques de proteine C reactive (CRP) en deca d’un seuil predefini entre le 3e et le 5e jour postoperatoire sont un marqueur fiable de l’absence de complication infectieuse apres chirurgie colorectale. Cependant, la strategie a mettre en place en cas de CRP elevee n’est pas codifiee. Le but de ce travail etait d’analyser l’utilite du scanner dans cette situation au sein d’une cohorte prospective de chirurgie colorectale reglee. Methodes Entre novembre 2011 et avril 2015, les patients ayant une CRP > 125 mg/L au 4e jour postoperatoire d’une resection colorectale reglee dans l’un des 2 centres participants ont ete inclus prospectivement dans une base. To…