Protection of railway infrastructure objects against electrical corrosion

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Liudmyla Trykoz ◽  
Svetlana Kamchatnaya ◽  
Dmytro Borodin ◽  
Armen Atynian ◽  
Roman Tkachenko
Keyword(s):  
Leakage Current ◽  
Electrical Resistance ◽  
Electrical Current ◽  
Leakage Currents ◽  
Destructive Effect ◽  
Accelerated Corrosion ◽  
Content Type ◽  
Pedestrian Bridges ◽  
Railway Infrastructure ◽  
Bridge Structures

Purpose The purpose of this paper is to develop a technological method of protection against electrical corrosion. One more way to protect the objects is to prevent the electrical current from getting to them. For example, railway objects are surrounded with a material with raised electrical resistance. Design/methodology/approach The railway infrastructure objects (foundations, contact-line supports, reinforced concrete sub-bases, bridge structures, pipelines of engineering networks, supports of passenger platforms and pedestrian bridges, concrete plinth walls of station buildings) are subjected to destruction due to the action of electrical current. One of destruction factors is a corrosion of the concrete constructions which is caused by the leakage current action. Findings Leakage currents and stray currents bypass the structure of supports of high passenger platforms or pipes of engineering networks. These currents spread by the line with the least resistance outside of the structures. Research limitations/implications Electrical leakage current from the rails gets into such structures through sleepers, ballast and soil and leads to accelerated corrosion leaching of concrete. Practical implications The constructions are protected against the destructive effect of electrical corrosion on the metal or concrete of the structure. This scheme is suitable for the construction and reconstruction of railway structures which operate on electrified sections of railways. Originality/value Schemes of technological solution are proposed for protection of foundations, supports of high passenger platforms, pipelines of engineering networks, etc. For this, the arrangement of soil-contained screens with big electrical resistance is suggested.

Microcontroller-based inverter topology integrated in PV systems

2015 ◽  
Vol 34 (1) ◽  
pp. 132-150 ◽  
Author(s):  
Mounir Bouzguenda ◽  
Tarek Selmi ◽  
Adel Gastli ◽  
Ahmed Masmoudi
Keyword(s):  
Leakage Current ◽  
Control Strategy ◽  
Design Methodology ◽  
Leakage Currents ◽  
Zero Crossing ◽  
Content Type ◽  
Pv Systems ◽  
High Conversion Ratio ◽  
Inverter Topology ◽  
Practical Implications

Purpose – The purpose of this paper is to study the problem of the leakage currents in transformerless inverter topologies. It proposes a novel topology and how important the adopted control strategy on the power quality produced by the inverter. Design/methodology/approach – The paper presents an investigation of a novel transformerless inverter topology. It adopted a control strategy in which the DC source is disconnected from the inverter when the zero vectors of the control are applied. By using such control strategy, the electrical efficiency of the whole system was improved and the leakage current was significantly reduced. Findings – The paper provides a solution to minimize the leakage current in transformerless inverter topologies. Besides, the problem of zero-crossing distortions was totally eliminated. Research limitations/implications – Because of the high conversion ratio of the boost converter, the efficiency of the whole system needs to be enhanced. Practical implications – The paper includes the experimental results of the proposed topology which are in good match with the simulation results. Originality/value – This paper identifies a need to study the leakage current phenomena in transformerless inverter topologies.

scholarly journals Effect of Applied Pressure on the Electrical Resistance of Carbon Nanotube Fibers

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2106
Author(s):  
Chris J. Barnett ◽  
James D. McGettrick ◽  
Varun Shenoy Gangoli ◽  
Ewa Kazimierska ◽  
Alvin Orbaek White ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Electrical Resistance ◽  
Copper Wire ◽  
Applied Pressure ◽  
Radial Strain ◽  
Electrical Current ◽  
Electrical Contacts ◽  
Electrical Performance ◽  
Macro Scale ◽  
Carbon Nanotube Fibers

Carbon nanotubes (CNTs) can be spun into fibers as potential lightweight replacements for copper in electrical current transmission since lightweight CNT fibers weigh <1/6th that of an equivalently dimensioned copper wire. Experimentally, it has been shown that the electrical resistance of CNT fibers increases with longitudinal strain; however, although fibers may be under radial strain when they are compressed during crimping at contacts for use in electrical current transport, there has been no study of this relationship. Herein, we apply radial stress at the contact to a CNT fiber on both the nano- and macro-scale and measure the changes in fiber and contact resistance. We observed an increase in resistance with increasing pressure on the nanoscale as well as initially on the macro scale, which we attribute to the decreasing of axial CNT…CNT contacts. On the macro scale, the resistance then decreases with increased pressure, which we attribute to improved radial contact due to the closing of voids within the fiber bundle. X-ray photoelectron spectroscopy (XPS) and UV photoelectron spectroscopy (UPS) show that applied pressure on the fiber can damage the π–π bonding, which could also contribute to the increased resistance. As such, care must be taken when applying radial strain on CNT fibers in applications, including crimping for electrical contacts, lest they operate in an unfavorable regime with worse electrical performance.

APPLICATION OF EPITAXIAL UNIPOLAR BARRIERS TO REDUCE NOISE CURRENTS IN PHOTODETECTORS

2011 ◽  
Vol 20 (03) ◽  
pp. 557-564
Author(s):  
G. R. SAVICH ◽  
J. R. PEDRAZZANI ◽  
S. MAIMON ◽  
G. W. WICKS
Keyword(s):  
Leakage Current ◽  
Surface Passivation ◽  
Leakage Currents ◽  
Type Region ◽  
Surface Leakage Current ◽  
Unipolar Barrier ◽  
Trap Assisted Tunneling ◽  
Assisted Tunneling ◽  
Tunneling Currents ◽  
Surface Leakage

Tunneling currents and surface leakage currents are both contributors to the overall dark current which limits many semiconductor devices. Surface leakage current is generally controlled by applying a post-epitaxial passivation layer; however, surface passivation is often expensive and ineffective. Band-to-band and trap assisted tunneling currents cannot be controlled through surface passivants, thus an alternative means of control is necessary. Unipolar barriers, when appropriately applied to standard electronic device structures, can reduce the effects of both surface leakage and tunneling currents more easily and cost effectively than other methods, including surface passivation. Unipolar barriers are applied to the p -type region of a conventional, MBE grown, InAs based pn junction structures resulting in a reduction of surface leakage current. Placing the unipolar barrier in the n -type region of the device, has the added benefit of reducing trap assisted tunneling current as well as surface leakage currents. Conventional, InAs pn junctions are shown to exhibit surface leakage current while unipolar barrier photodiodes show no detectable surface currents.

Environmental tests of embedded thin- and thick-film resistors in comparison to chip resistors

Circuit World ◽  
2014 ◽  
Vol 40 (1) ◽  
pp. 7-12 ◽  
Author(s):  
Wojciech Steplewski ◽  
Andrzej Dziedzic ◽  
Janusz Borecki ◽  
Grazyna Koziol ◽  
Tomasz Serzysko
Keyword(s):  
Thin Film ◽  
Thick Film ◽  
Electrical Resistance ◽  
Printed Circuit Boards ◽  
Base Material ◽  
Forming Process ◽  
Content Type ◽  
Thin Film Resistors ◽  
Embedded Resistors ◽  
The Impact

Purpose – The purpose of this paper is to investigate the influence of parameters of embedded resistive elements manufacturing process as well as the influence of environmental factors on their electrical resistance. The investigations were made in comparison to the similar constructions of discrete chip resistors assembled to standard printed circuit boards (PCBs). Design/methodology/approach – The investigations were based on the thin-film resistors made of NiP alloy, thick-film resistors made of carbon or carbon-silver inks as well as chip resistors in 0402 and 0603 packages. The polymer thick-film resistive films were screen-printed on the several types finishing materials of contact terminations such as copper, silver, and gold. To determine the sensitivity of embedded resistors versus standard assembled chip resistors on environmental exposure, the climatic chamber was used. The measurements of resistance were carried out periodically during the tests, and after the exposure cycles. Findings – The results show that the change of electrical resistance of embedded resistors, in dependence of construction and base material, is different and mainly not exceed the range of 3 per cent. The achieved results in reference to thin-film resistors are comparable with results for standard chip resistors. However, the results that were obtained for thick-film resistors with Ag and Ni/Au contacts are similar. It was not found the big differences between resistors with and without conformal coating. Research limitations/implications – The studies show that embedded resistors can be used interchangeably with chip resistors. It allows to save the area on the surface of PCB, occupied by these passive elements, for assembly of active elements (ICs) and thus enable to miniaturization of electronic devices. But embedding of passive elements into PCB requires to tackle the effect of each forming process steps on the operational properties. Originality/value – The technique of passive elements embedding into PCB is generally known; however, there are no detailed reports on the impact of individual process steps and environmental conditions on the stability of their electrical resistance. The studies allow to understand the importance of each factor process and the mechanisms of operational properties changes depending on the used materials.

Rotating co-flow jets with horizontal lip and shape transition

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Dawn Pradeeb S. A. ◽  
Subramanian Thanigaiarasu ◽  
Nagarajakrishnan Premanand
Keyword(s):  
Nozzle Exit ◽  
Large Scale ◽  
Metal Cutting ◽  
Flame Length ◽  
Equivalent Diameter ◽  
Exit Plane ◽  
Interesting Phenomenon ◽  
Destructive Effect ◽  
Outer Flow ◽  
Content Type

Purpose Control over large-scale coherent structures and stream-wise vortices lead to enhanced entrainment/conservation of the jet which is desirable for most free jet applications such as design of combustion chamber in jet engines and flame length elongation of welding torch used for metal cutting. Design/methodology/approach A co-flow nozzle with lip thickness of 2 mm, between the primary (inner) and secondary (outer) flow, is selected. Three nozzle combinations are used, i.e. C–C (circle–circle), C–E (circle–ellipse) and C–S (circle–square) for acquiring comparative data. For these nozzle combinations, inner nozzle exit plane is kept as a circle, whereas the outer nozzle exit planes are varied to circle, ellipse and square. The exit plane area of outer nozzle for the nozzle combinations has equivalent diameter, De. The nozzles are fabricated in a way that the outer nozzle can be rotated along the longitudinal axis, keeping the inner nozzle intact. Findings The C–C nozzle combination is effective in low Mach number regime in decaying the jet, when the rotational component is introduced. Around 30% reduction in the jet core length is observed for the C–C nozzle combinations without any lip. The C–E nozzle shows sedative result in decaying or preserving the jet. The C–S nozzle combination shows interesting phenomenon, whereby the low subsonic case tends to conserve the jet by 15% and the higher subsonic case tends to decay the jet by 10%. Originality/value The developed nozzle systems show both conservative and destructive effect on the jet, which is desirable for the mentioned applications.

Research on the delamination wear properties of the pure carbon strip at the high-sliding speed with electric current

2018 ◽  
Vol 70 (1) ◽  
pp. 76-83 ◽  
Author(s):  
Hongjuan Yang ◽  
Lin Fu ◽  
Yanhua Liu ◽  
Weiji Qian ◽  
Bo Hu
Keyword(s):  
Electric Current ◽  
High Speed ◽  
Normal Load ◽  
Copper Wire ◽  
Electrical Current ◽  
Wear Properties ◽  
Sliding Speed ◽  
Content Type ◽  
Delamination Wear ◽  
High Speed Data

Purpose This paper aims to investigate the delamination wear properties of a carbon strip in a carbon strip rubbing against a copper wire at the high-sliding speed (380 km/h) with or without electrical current. Design/methodology/approach The friction and wear properties of a carbon strip in a carbon strip rubbing against a copper wire are tested on the high-speed wear tester whose speed can reach up to 400 km/h. The test data have been collected by the high-speed data collector. The worn surfaces of the carbon strip are observed by the scanning electron microscope. Findings It was found that there was a significant increase of the delamination wear with the decrease of the normal load when the electric current is applied. The size of the flake-like peeling also increases with the decrease of normal load. The delamination wear extends gradually from the edge of the erosion pits to the surrounding area with the decrease of the normal load. However, the delamination wear never appears in the absence of electric current. It is proposed that the decreased normal load and the big electrical current are the major causes of the delamination wear of the carbon strip. Originality value The experimental test at high-sliding speed of 380 km/h was performed for the first time, and the major cause of the delamination was discovered in this paper.

scholarly journals KLECTOR: Design of Low Power Static Random-Access Memory Architecture with reduced Leakage Current

2021 ◽  
Author(s):  
Ananth Kumar Tamilarasan ◽  
Darwin Sundarapandi Edward ◽  
Arun Samuel Thankamony Sarasam
Keyword(s):  
Leakage Current ◽  
Random Access ◽  
Static Random Access Memory ◽  
Memory Architecture ◽  
Access Memory ◽  
Leakage Currents ◽  
Output Node ◽  
Voltage Drops ◽  
Novel Approach ◽  
Standby Mode

Abstract A novel approach called Keeper in LEakage Control Transistor (KLECTOR) is presented in this paper to reduce leakage currents in SRAM architecture. The SRAM is significantly affected by the leakage current during the "standby mode", which is caused by the fabric which has a lower threshold voltage. KLECTOR circuit employs less power consumption by restricting the flow of current through devices of less voltage drops and relies heavily on the self-controlled transistor at the output node. It has been found from the presented results that static (leakage) power in the write operation is reduced to 63% and 69 % for the read operation. This proposed approach is designed and simulated using the Virtuoso, Cadence EDA tool.

scholarly journals Studi Pola Arus Bocor Isolator Keramik Selama Waktu Pemakaian 24 Jam

2020 ◽  
Vol 3 (3) ◽  
Author(s):  
Dini Fauziah ◽  
Waluyo Waluyo ◽  
Ismail Muhammad Khaidir
Keyword(s):  
Ambient Temperature ◽  
Electric Power ◽  
Leakage Current ◽  
Distribution System ◽  
Power Transmission ◽  
Current Data ◽  
Electric Power System ◽  
Leakage Currents ◽  
Ceramic Insulator ◽  
Distribution System Reliability

ABSTRAK Isolator merupakan komponen yang penting dijaga keandalannya dalam sistem transmisi dan distribusi tenaga listrik. Isolator rentan mengalami kegagalan akibat lingkungan, karena terpapar langsung kondisi dimana isolator tersebut terpasang. Salah satu jenis isolator yang sering digunakan adalah bahan keramik, dimana memiliki kelebihan diantaranya kekuatan mekanik yang cukup handal. Namun kekurangan isolator jenis ini adalah sifat permukaannya yang hidrofilik, yaitu mudah menyerap air sehingga bila digunakan pada kelembaban tinggi cenderung memicu timbulnya arus bocor. Arus bocor merupakan parameter penting pada isolator karena sering menjadi penyebab kegagalan isolator. Untuk mengetahui seberapa besar pengaruh kondisi lingkungan terhadap arus bocor, dilakukan pengujian terhadap isolator keramik dalam waktu 24 jam. Data arus bocor diambil setiap 3 jam untuk melihat perubahannya berdasarkan perubahan kelembaban, dan suhu lingkungan. Hasilnya didapat bahwa semakin tinggi kelembaban udara, dan semakin rendah suhu lingkungan maka arus bocor semakin tinggi. Hasil penelitian ini dapat dijadikan acuan untuk mengantisipasi kegagalan isolator keramik akibat arus bocor sehingga keandalan sistem tenaga listrik dapat terjaga. Kata kunci: Isolator keramik, Lingkungan, Kelembaban, Suhu. ABSTRACT Isolator is an important component that must be maintained to keep electric power transmission and distribution system reliability. Isolators are susceptible to failure due to the environment, because they are directly exposed to conditions where the insulator installed. Ceramic insulator is one type of isolator that is often used, which has advantages including mechanical strength that is quite reliable. However, the lack of this type of isolator is its hydrophilic surface, which is easy to absorb water so that when used at high humidity tends to trigger a leakage current. Leakage current is an important parameter in an insulator because it can be a cause due to insulator failure. To find out how environmental conditions impact on leakage currents along day, a ceramic isolator is tested within 24 hours. Leakage current data is taken every 3 hours to see the changes based on changes in humidity, and ambient temperature. The result is the higher humidity of the air, and the lower ambient temperature, can make insulator leakage current rise up. The results of this study can be used as a reference to anticipate the failure of ceramic insulators due to leakage currents so that the reliability of the electric power system can be maintained. Keywords: ceramic insulator, environtment, humidity, temperature.

Electrical Characteristics of Large Chip-Size 3.3 kV SiC-JBS Diodes

2013 ◽  
Vol 740-742 ◽  
pp. 881-886 ◽  
Author(s):  
Hiroyuki Okino ◽  
Norifumi Kameshiro ◽  
Kumiko Konishi ◽  
Naomi Inada ◽  
Kazuhiro Mochizuki ◽  
...  
Keyword(s):  
Electric Field ◽  
Schottky Barrier ◽  
Leakage Current ◽  
Reverse Current ◽  
Tunneling Current ◽  
Leakage Currents ◽  
Reverse Leakage Current ◽  
Low Leakage ◽  
Chip Size ◽  
Barrier Metal

The reduction of reverse leakage currents was attempted to fabricate 4H-SiC diodes with large current capacity for high voltage applications. Firstly diodes with Schottky metal of titanium (Ti) with active areas of 2.6 mm2 were fabricated to investigate the mechanisms of reverse leakage currents. The reverse current of a Ti Schottky barrier diode (SBD) is well explained by the tunneling current through the Schottky barrier. Then, the effects of Schottky barrier height and electric field on the reverse currents were investigated. The high Schottky barrier metal of nickel (Ni) effectively reduced the reverse leakage current to 2 x 10-3 times that of the Ti SBD. The suppression of the electric field at the Schottky junction by applying a junction barrier Schottky (JBS) structure reduced the reverse leakage current to 10-2 times that of the Ni SBD. JBS structure with high Schottky barrier metal of Ni was applied to fabricate large chip-size SiC diodes and we achieved 30 A- and 75 A-diodes with low leakage current and high breakdown voltage of 4 kV.

scholarly journals Fast and Sensitive Detection of Bacillus anthracis Spores by Immunoassay

2012 ◽  
Vol 78 (18) ◽  
pp. 6491-6498 ◽  
Author(s):  
Nathalie Morel ◽  
Hervé Volland ◽  
Julie Dano ◽  
Patricia Lamourette ◽  
Patricia Sylvestre ◽  
...  
Keyword(s):  
Bacillus Anthracis ◽  
Electrical Current ◽  
Biological Weapons ◽  
Meso Scale Discovery ◽  
Simple Method ◽  
Content Type ◽  
Bacillus Anthracis Spores ◽  
Luminescent Signal ◽  
Sample Purification ◽  
Phosphate Buffered Saline

ABSTRACTBacillus anthracisis one of the most dangerous potential biological weapons, and it is essential to develop a rapid and simple method to detectB. anthracisspores in environmental samples. The immunoassay is a rapid and easy-to-use method for the detection ofB. anthracisby means of antibodies directed against surface spore antigens. With this objective in view, we have produced a panel of monoclonal antibodies againstB. anthracisand developed colorimetric and electrochemiluminescence (ECL) immunoassays. Using Meso Scale Discovery ECL technology, which is based on electrochemiluminescence (ECL) detection utilizing a sulfo-Tag label that emits light upon electrochemical stimulation (using a dedicated ECL plate reader, an electrical current is placed across the microplate with electrodes integrated into the bottom of the plate, resulting in a series of electrically induced reactions leading to a luminescent signal), a detection limit ranging between 0.3 × 103and 103CFU/ml (i.e., 30 to 100 spores per test), depending on theB. anthracisstrain assayed, was achieved. In complex matrices (5 mg/ml of soil or simulated powder), the detection level (without any sample purification or concentration) was never altered more than 3-fold compared with the results obtained in phosphate-buffered saline.

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