Lightning impulse breakdown voltage RBDPO with the presence of metallic particles under a uniform electric field

The performance of liquid insulation in power transformer is vulnerable to particles, especially the metallic particles. This paper presents the experimental study on the effect of metallic particles on the palm oil (PO) as dielectric insulating fluid under lightning impulse breakdown voltage. The type of PO used in this study is refined, bleached and deodorized Palm Oil (RBDPO) Olein. Two different types of metallic particles (copper and iron) with different concentrations (clean, low, medium, and high) were studied. The lightning impulse test has been carried out according to IEC 60897 standard and under the influence of a uniform electric field. For the comparative purpose, similar test has been carried out with mineral oil (MO). The presence of metallic particles reduces the average lightning impulse breakdown voltage of MO and PO but shows less significant effect to MO. This is because the streamers in the PO propagate faster and further than in the MO at the same voltage level. Hence, causing the breakdown voltage of PO lower than MO. Under negative lightning impulse, the breakdown voltage of MO is slightly higher than RBDPO. From the study, the increment of the number of particle level contamination will reduce the lightning impulse breakdown voltages of the PO

Radiation pattern performance of bow tie patch antenna for ground penetrating radar (GPR) applications

This paper presents a directional bow tie patch antenna for ground penetrating radar (GPR) applications. There are four proposed designs for this paper. Three of the antenna is designed by introducing Sierpinski gasket fractal concept on bow tie patch antenna. There is some modification on this design in order to create a new different fractal design that is applicable for GPR applications. The bow tie antenna performance is studied across 1 GHz to 4 GHz. The best return loss obtained for this paper is at 3.7 GHz where all four designs have its best performance. The comparison at 3.7 GHz of these four antenna designs presented in this pape

Smart control and management system for hydroponic plant growth

Hydroponics is one of the cultivation methods that uses water as a plant growth medium. In this technique, a mineral solution is added to the water solvent, which enables the process of nutrient uptake by the plant. Several important parameters need to be observed to use hydroponic cultivation methods such as temperature, humidity, water, and nutrient requirements. Sunlight is also needed for the process of photosynthesis to take place. This research uses hydroponic techniques in a hydroponic growth space, with LED growth lights as an alternative to sunlight because the space is covered without sunlight. Monitoring of the output in the box was detected using a temperature sensor, a humidity sensor, an ultrasound sensor to detect the height of the plant, and a water level sensor with the height of the water measured as the plant medium. The sensor measurement results in the hydroponic growth chamber are described as follows: the fan cooler operates when the temperature is > 30oC, and the humidity > 60%. The water pump works when the water level is less than 50% of the set point. Control on the lights was carried out with the LDR sensors each reaching a setting point of >500 in bright conditions, and <500 in dark conditions. The average update / data time received in the web is 2.4 seconds

A Review On Oil-Based Nanofluid As Next-Generation Insulation For Transformer Application

Due to the increasing demand on developing good insulation, several researchers have performed experimental studies to prove the effectiveness and capabilities of transformer oil. This is done by suspending nanosized solid particles in the oil (nanofluid) for transformer applications. In brief, this paper presents a compilation of research studies which is divided into three parts. Part I discuss the preparation of the nanofluid which involves different types of nanomaterials, the optimal amount of concentrations, and applicable synthesisation methods for producing stably suspended nanofluids. In Part II, the nanofluid’s performances including the electrical breakdown voltages, impulse tests, and thermal and dielectric behaviour are reviewed in depth and compared. Part III emphasizes the limitation of nanofluids. Most researchers have agreed that appropriate concentrations of nanomaterials and the preparation method for nanofluids mainly affect the performance of nanofluids especially in terms of electrical properties. Meanwhile, types of nanomaterials and base oil also play a vital role in producing nanofluids as a better alternative transformer oil. However, among a few researchers, there are concerns regarding the issue of agglomeration and inconsistencies of findings that need to be resolved. Therefore, a few aspects must be taken into consideration to produce the next generation of high heat dissipation insulation

Magnetism And Thermomechanical Properties In Si Substituted MnCoGe Compounds

MnCoGe-based compounds have been increasingly studied due to their possible large magnetocaloric effect correlated to the magnetostructural coupling. In this research, a comprehensive study of structure, magnetic phase transition, magnetocaloric effect and thermomechanical properties for MnCoGe1−xSix is reported. Room temperature X-ray diffraction indicates that the MnCoGe1−xSix (x = 0, 0.05, 0.1, 0.15 and 0.2) alloys have a major phase consisting of an orthorhombic TiNiSi-type structure with increasing lattice parameter b and decreasing others (a and c) with increasing Si concentration. Along with M-T and DSC measurements, it is indicated that the Tc value increased with higher Si concentration and decreased for structural transition temperature Tstr. The temperature dependence of the magnetization curves overlaps completely, indicating that there is no thermal hysteresis, and it is shown that the transition is the second-order type. It is also shown that the decreased magnetization on the replacement of Si for Ge decreases the value of −ΔSM from −ΔSM~8.36 J kg−1 K−1 at x = 0 to −ΔSM~5.49 J kg−1 K−1 at x = 0.2 with 5 T applied field. The performed Landau theory has confirmed the second-order transition in this study, which is consistent with the Banerjee criterion. The magnetic measurement and thermomechanical properties revealed the structural transition that takes place with Si substitution of G

Development of MPLS test-bed for network traffic engineering

Providing Quality of Service (QoS) and Traffic Engineering (TE) capabilities in the Internet is essential, especially in supporting the requirement of real-time traffic, as well as mission critical applications. For that reason, the current Internet must be enhanced with new technology that enables it to offer capabilities for controlling its behaviour as needed. Multiprotocol Label Switching (MPLS) is an emerging technology that provides QoS and traffic engineering features in IP network. This study is mainly concerned on how to develop MPLS test-bed in order to assess MPLS functionalities. The goal is to develop MPLS test-bed using Linux operating system with kernel version 2.6.5 as the platform. In this work the MPLS test-bed consists of four MPLS routers and two host terminals. MPLS software package version 1.946 has been used to build up routers similar to existing routers in MPLS domain called as Label Switched Router (LSR). Once the routers are well configured, the connection between two routers is established to create Label Switched Path (LSP). This LSP connection is also used to create new LSP from ingress router to egress router. IP packets are sent from ingress router to host terminals to validate the test-bed. These packets were encapsulated with MPLS header and they are examined by using ‘tcpdump’ command in Linux terminal which shows that the test-bed is successfully developed. In order to enhance test-bed functionalities, packet generator can be added to the test-bed so that UDP and TCP throughput measurement can be done. Besides, RSVP and Diffserv can be integrated into the test-bed for future study

Étude et conception d'antennes reconfigurables basées sur des matériaux plasma

Plasma is the 4th state of matter with complex permittivity that can be exploited to give advantages in communication system. Its negative permittivity has been studied in many research papers and it was proven to have similar characteristics as metal material in terms of electrical conductivity. While keeping permeability in the positive region, plasma will respond to electromagnetic waves in the similar manner as metal. Therefore, this thesis aimed to use plasma as an alternative to metal in the construction of reconfigurable antennas. The first part of this thesis is dedicated to characterize a plasma model based on the commercially available plasma source. Since there are many type of plasma source in terms of their electrical properties and physical shapes, it is important to characterize a particular plasma source so that it can be modeled in simulations to construct other types of plasma antennas. The second part presents the realization of plasma reflector antennas. Two types of plasma reflector antennas have been simulated, fabricated and measured at 2.4 GHz. The first one is are round reflector antenna (RRA) and the second one is corner reflector antenna (CRA). The performances of RRA have been validated and it was proven to provide beam shaping and beam scanning capability. The measured radiation patterns are in a good agreement with simulation ones. The capability of RRA is exceptional since it can steer its main beam from 0° up to 360°. Moreover, the scanning gain remains the same as the main beam is being moved from one direction to another. The CRA that has been introduced in this thesis is a novel design since it integrates two corner-reflector antennas on a single ground plane. The CRA offers three beam shapes which are electrically switchable from one shape to another. The CRA was simulated, fabricated and finally its performances were validated throughout a series of agile measurements. The measured reflected radiation patterns are in good agreements with the simulation ones. The measured gains of the RRA and CRA are 5 dB higher than the gain of classical monopole antenna with an identical size of finite ground plane. The fourth part deals with plasma as radio waves radiator. Two plasma antennas using commercially available U-shaped compact fluorescent lamp (CFL) have been fabricated and measured and it was proven that these antennas can be to radiate radio signal. The last part discusses about radar cross section performance of the plasma reflector antennas. The two plasma reflector antennas (RRA and CRA) were tested and measured for their RCS performance.Le milieu plasma correspond au 4ème état de la matière présentant une permittivité diélectrique complexe qui peut être exploitée pour les systèmes de communication. Sa permittivité négative a été étudiée dans de nombreux travaux de recherche démontrant que le plasma peut avoir des caractéristiques similaires à celles d'un métal en termes de conductivité électrique. En considérant une perméabilité positive, le plasma peut ainsi réagir de la même manière qu'un métal en présence d'une onde électromagnétique. Cette thèse a pour objectif de démontrer que le plasma est une alternative au métal pour la réalisation d'antennes reconfigurables. La première partie du travail concerne la caractérisation du milieu plasma en utilisant des sources plasma commerciales à savoir des lampes à Néon. Cette caractérisation est primordiale afin de pouvoir ensuite simuler ce type de source. La seconde partie des recherches a concerné la conception et la réalisation d'antennes plasma reconfigurables en rayonnement et ceci à la fréquence de 2.4 GHz. Le premier concept est un réflecteur circulaire et le second un réflecteur à angle droit tous les deux réalisés à partir de différentes lampes à Néon et illuminés par une antenne source monopole. Le réflecteur circulaire permet de dépointer le faisceau d'antennes sur 360° alors que le réflecteur à angle droit permet de reconfigurer le faisceau rayonnant et de passer d'un faisceau directif à deux faisceaux avec un creux dans l'axe. Ces dispositifs rayonnants innovants basés sur des lampes à Néon ont été validés expérimentalement et les résultats de mesure (S11 et rayonnement) sont en bonne adéquation avec les résultats de simulation. Ces deux types d'antennes réflecteurs possèdent également de bons résultats en termes de gain, ce qui valide l'utilisation et la caractérisation des lampes plasma de commerce utilisées. Dans la troisième partie du travail, ce même type de lampe à néon a été utilisé pour concevoir cette fois un élément rayonnant excité par couplage capacitif. La réalisation d'un prototype à permis de démontrer la faisabilité d'une telle source rayonnante. Enfin, la dernière partie des recherches concerne une étude de la Surface Equivalente Radar des antennes réflecteur conçues précédemment. L'étude a démontré que ces antennes réflecteurs plasma présentent des SER largement inférieures lorsqu'elles sont éteintes ainsi qu'à fréquence haute (8 GHz) comparativement à celles d'antennes métalliques équivalentes ce qui en fait des antennes furtives d'un point de vue radar

Étude et conception d'antennes reconfigurables basées sur des matériaux plasma

Le milieu plasma correspond au 4ème état de la matière présentant une permittivité diélectrique complexe qui peut être exploitée pour les systèmes de communication. Sa permittivité négative a été étudiée dans de nombreux travaux de recherche démontrant que le plasma peut avoir des caractéristiques similaires à celles d'un métal en termes de conductivité électrique. En considérant une perméabilité positive, le plasma peut ainsi réagir de la même manière qu'un métal en présence d'une onde électromagnétique. Cette thèse a pour objectif de démontrer que le plasma est une alternative au métal pour la réalisation d'antennes reconfigurables. La première partie du travail concerne la caractérisation du milieu plasma en utilisant des sources plasma commerciales à savoir des lampes à Néon. Cette caractérisation est primordiale afin de pouvoir ensuite simuler ce type de source. La seconde partie des recherches a concerné la conception et la réalisation d'antennes plasma reconfigurables en rayonnement et ceci à la fréquence de 2.4 GHz. Le premier concept est un réflecteur circulaire et le second un réflecteur à angle droit tous les deux réalisés à partir de différentes lampes à Néon et illuminés par une antenne source monopole. Le réflecteur circulaire permet de dépointer le faisceau d'antennes sur 360 alors que le réflecteur à angle droit permet de reconfigurer le faisceau rayonnant et de passer d'un faisceau directif à deux faisceaux avec un creux dans l'axe. Ces dispositifs rayonnants innovants basés sur des lampes à Néon ont été validés expérimentalement et les résultats de mesure (S11 et rayonnement) sont en bonne adéquation avec les résultats de simulation. Ces deux types d'antennes réflecteurs possèdent également de bons résultats en termes de gain, ce qui valide l'utilisation et la caractérisation des lampes plasma de commerce utilisées. Dans la troisième partie du travail, ce même type de lampe à néon a été utilisé pour concevoir cette fois un élément rayonnant excité par couplage capacitif. La réalisation d'un prototype à permis de démontrer la faisabilité d'une telle source rayonnante. Enfin, la dernière partie des recherches concerne une étude de la Surface Equivalente Radar des antennes réflecteur conçues précédemment. L'étude a démontré que ces antennes réflecteurs plasma présentent des SER largement inférieures lorsqu'elles sont éteintes ainsi qu'à fréquence haute (8 GHz) comparativement à celles d'antennes métalliques équivalentes ce qui en fait des antennes furtives d'un point de vue radar.Plasma is the 4th state of matter with complex permittivity that can be exploited to give advantages in communication system. Its negative permittivity has been studied in many research papers and it was proven to have similar characteristics as metal material in terms of electrical conductivity. While keeping permeability in the positive region, plasma will respond to electromagnetic waves in the similar manner as metal. Therefore, this thesis aimed to use plasma as an alternative to metal in the construction of reconfigurable antennas. The first part of this thesis is dedicated to characterize a plasma model based on the commercially available plasma source. Since there are many type of plasma source in terms of their electrical properties and physical shapes, it is important to characterize a particular plasma source so that it can be modeled in simulations to construct other types of plasma antennas. The second part presents the realization of plasma reflector antennas. Two types of plasma reflector antennas have been simulated, fabricated and measured at 2.4 GHz. The first one is are round reflector antenna (RRA) and the second one is corner reflector antenna (CRA). The performances of RRA have been validated and it was proven to provide beam shaping and beam scanning capability. The measured radiation patterns are in a good agreement with simulation ones. The capability of RRA is exceptional since it can steer its main beam from 0 up to 360. Moreover, the scanning gain remains the same as the main beam is being moved from one direction to another. The CRA that has been introduced in this thesis is a novel design since it integrates two corner-reflector antennas on a single ground plane. The CRA offers three beam shapes which are electrically switchable from one shape to another. The CRA was simulated, fabricated and finally its performances were validated throughout a series of agile measurements. The measured reflected radiation patterns are in good agreements with the simulation ones. The measured gains of the RRA and CRA are 5 dB higher than the gain of classical monopole antenna with an identical size of finite ground plane. The fourth part deals with plasma as radio waves radiator. Two plasma antennas using commercially available U-shaped compact fluorescent lamp (CFL) have been fabricated and measured and it was proven that these antennas can be to radiate radio signal. The last part discusses about radar cross section performance of the plasma reflector antennas. The two plasma reflector antennas (RRA and CRA) were tested and measured for their RCS performance.RENNES1-Bibl. électronique (352382106) / SudocSudocFranceF

Performance and Radiation Patterns of A Reconfigurable Plasma Corner-Reflector Antenna

Abstract—A novel reconfigurable plasma corner reflector antenna is proposed to better collimate the energy in forward direction operating at 2.4GHz. Implementation of a low cost plasma element permits beam shape to be changed electrically. The maximum measured gains are 5.7dBi, 10.8dBi and 10.5dBi for the omnidirectional, single and double beam shapes respectively. Index Terms—Corner reflector antenna, plasma corner reflector antenna, plasma antenna, reconfigurable antenna, reconfigurable plasma antenna. S I

Performance of a reconfigurable reflector antenna with scanning capability using low cost plasma elements

International audienceA reflector antenna with rounded shape is designed to collimate beam radiated by a quarter wave antenna operating at 2.4 GHz by implementing low cost plasma elements. The measured gain is 9 dBi, cross-polarization remains below -10 dB and operating bandwidth of the antenna is almost 46 percent