Search results for "Discharge"
showing 10 items of 424 documents
A new approach for deducing the stage-discharge relationship of a triangular broad-crested device
2022
In this paper, the outflow process of a triangular broad-crested device is examined using the dimensional analysis and the incomplete self-similarity theory. A new theoretical stage-discharge relationship is proposed, and its applicability is verified using measurements available in literature. The proposed power equation is characterized by a coefficient depending on device apex angle and a constant value of the exponent.
Deducing the stage-discharge relationship of rectangular broad and sharp-crested contraction devices
2023
Flumes with a local contraction of the channel width are a common way for accurately measuring the flow discharge. In this paper, the outflow process of rectangular broad and sharp-crested contraction devices is modeled using the dimensional analysis and the incomplete self-similarity condition. The proposed theoretical stage-discharge relationship is tested using measurements available in the literature. The proposed power equation is characterized by a value of the exponent close to 1.5 and a coefficient depending on the contraction ratio. The proposed flow-measuring flumes are characterized by a good accuracy of the measured discharge (ranging from -2.71 to 3.28% for the broad-crested co…
Stage-discharge relationship for an upstream inclined grid with transversal bars
2016
Check dams with grids upgrading upstream are often used in mountain rivers, where intense sediment transport and steep slopes occur. In some cases, sloping grids are used in the construction of debris flow breakers. In this paper, the outflow process of an upstreaminclined grid with transversal bars is studied by using the dimensional analysis and the incomplete self-similarity theory. Next, the theoretical analysis shows that a power equation can be used for establishing the stage-discharge equation. The coefficient of the power equation depends on both the slope angle and the void ratio, whereas the exponent depends only on the slope angle. Finally, this deduced stage-discharge relationsh…
Closure "Stage-discharge relationship for an upstteam inclined grid with transversal bars"
2016
The paper is a closure of “Stage-Discharge Relationship for an Unpstream Inclined Grid with Transversal Bars”
SURFACE ROUGHNESS PREDICTION OF ELECTRO-DISCHARGE MACHINED COMPONENTS USING ARTIFICIAL NEURAL NETWORKS
2016
Electro-Discharge machining (EDM) is a thermal process comprising a complex metal removal mechanism, which involves the formation of a plasma channel between the tool and the workpiece electrodes leading to the melting and evaporation of the material to be removed. EDM is considered especially suitable for machining complex contours with high accuracy, as well as for materials that are not amenable to conventional removal methods. However, several phenomena negatively affecting the surface integrity of EDMed workpieces need to be taken into account and studied in order to achieve the optimization of the process. Recently, artificial neural networks (ANN) have emerged as a novel modeling tec…
Test procedures for use of wireless partial discharges instrumentation in HV networks
2014
On-field diagnostic methods based on Partial Discharge (PD) measurements for asset assessment in High Voltage (HV) sectors are experiencing a constant growth in recent years. This rise of interest motivated the research toward faster, reliable and less expensive methods and technologies to perform PD measurements. Recently, a portable instrument based on a wideband antenna sensor, intended for accurate partial discharge measurements, has been developed by the authors. This sensor allows to capture electromagnetic waves in a bandwidth ranging from 0.1-100 MHz as well as the electric field of the AC supply voltage to be used as a phase reference. This approach completely avoid the need of a d…
Predictability of PD inception in defects included in HVDC cables by conductivity models calibrated through experiments
2022
To date, there are several methods for calculating the electric field distribution within a dielectric layer subjected to HVDC voltage. However, experimental techniques for evaluating the accuracy of models for calculating the electric field, such as space charge measurement, are often not precise enough to be used for this purpose. At the same time, the knowledge of Partial Discharge (PD) phenomenon occurring under HVDC stress is also not as developed as that of PD under HVAC voltage. The main goal of this research is to study the effectiveness of dielectric conductivity models to forecast the inception condition for PD under load and HVDC voltage stress. This study has been carried out by…
Design and Simulation of Fast Discharge Units (FDUs) for Toroidal Field Coils of Divertor Tokamak Test (DTT)
2023
Questa tesi riassume il lavoro svolto durante il triennio di dottorato nel periodo compreso tra il 2019 e il 2022. Come è ben noto nella comunità scientifica, l'ambiziosissimo progetto di fusione nucleare ha richiesto e richiede notevoli risorse ed investimenti; La tabella di marcia per la generazione di energia da fusione nucleare su larga scala comprende missioni impegnative. I progetti ITER e DEMO, essendo progetti internazionali, richiedono la collaborazione (sia dal punto di vista economico che tecnico) di diversi Paesi a livello europeo ed extraeuropeo; per questo motivo i vari aspetti tecnologici, che verranno poi implementati e applicati nei reattori a fusione finali, vengono prima …
Performances of a PCB-based Loop Antenna Inductive Sensor for Partial Discharges Detection
2022
This paper presents the test results of an electrically small loop antenna sensor towards detecting the radiated magnetic field due to partial discharge (PD) activities. The loop antenna prototype was printed on an FR-4 substrate with a thickness of 1.6 mm, featuring a compact size of 20 mm times20 mm times1.7 mm. The proposed sensor, initially simulated with Ansys HFSS software, has a resonant frequency of about 100 MHz. Its detection capability for three types of partial discharges (i.e., corona, surface and internal PDs) has been evaluated. Laboratory experiments showed that the evaluated loop spiral antenna is appropriate for the detection of the three types of PDs. Indeed, the results …
Partial discharges characteristics during load transients in an HVDC model cable
2021
The occurrence of Partial Discharges (PD) in HVAC cables is widespread considered as one of the most important concerns for the stability of the insulation. To date, the role of PD in the ageing and definitive fault of HVDC cables has been poorly investigated. This is mainly due to some practical difficulties in the performing of the measurements. Compared to the PDs occurring under AC stress, the higher inception voltages and the lower repetition rates, obtainable under DC voltage, make the exclusion of the measurement noise more difficult. This paper is focused on the study of the characteristics of the PDs occurring in an artificial defect located in proximity of the outer dielectric' su…