Novel approach to numerical equivalence investigations on synthetic circuits for circuit-breaker testing

G. Witte; K. Möller

doi:10.1002/etep.4450040207

A Novel Approach to Power Circuit Breaker Design for Replacement of SF6

Acta Polytechnica ◽

10.14311/548 ◽

2004 ◽

Vol 44 (2) ◽

Author(s):

D. J. Telfer ◽

J. W. Spencer ◽

G. R. Jones ◽

J. E. Humphries

Keyword(s):

Circuit Breaker ◽

Circuit Breakers ◽

Power Circuit ◽

Current Interruption ◽

Novel Approach ◽

Different Gases ◽

Critical Contact ◽

Made In ◽

Gas Pressures

This contribution explores the role of PTFE ablation in enhancing current interruption for various background gases in high voltage circuit breakers. An assessment of the current interruption capability has been made in terms of the arcing duration and the contact gap length at which critical arc extinction is achieved. These observations are supported by measurements of the magnitude of extinction and re-ignition voltage peaks. Most previous and other current experimental work on gas filled circuit breaker design follows conventional wisdom in investigating arcing behaviours at elevated gas pressures (usually up to 6 bar). But in this work we concentrate on the effects of using low gas pressures (less than 1 bar) in the presence of a close-fitting shield of ablatant polymer material (PTFE) that surrounds the electrode assembly of an experimental high power circuit breaker. We demonstrate that for several different gases, arc extinction capability compares well under these conditions with SF6, suggesting that SF6 could be replaced entirely in this novel system by more environmentally friendly gases. Moreover, the critical contact gap lengths at extinction are only slightly greater than when using SF6 at 6 bar. Weight loss measurements from the ablatant shield suggest that a chemical puffer action is the most likely mechanism for achieving the observed arc extinctions in this system.

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Bagged Decision Trees Based Scheme of Microgrid Protection Using Windowed Fast Fourier and Wavelet Transforms

10.20944/preprints201803.0272.v1 ◽

2018 ◽

Author(s):

Solomon Netsanet Alemu ◽

Jianhua Zhang ◽

Dehua Zheng

Keyword(s):

Decision Trees ◽

Wavelet Transforms ◽

Distribution Systems ◽

Circuit Breaker ◽

Great Level ◽

Detection Scheme ◽

Novel Approach ◽

Bagged Decision Trees ◽

The Right ◽

Beijing China

Microgrids of varying size and applications are regarded as a key feature of modernizing the power system. The protection of those systems, however, has become a major challenge and a popular research topic for the reason that it involves greater complexity than traditional distribution systems. This paper addresses the issue through a novel approach which utilizes detailed analysis of current and voltage waveforms through windowed fast Fourier and wavelet transforms. The fault detection scheme involves bagged decision trees which use input features extracted from the signal processing stage and selected by correlation analysis. The technique was tested on a microgrid model developed using PSCAD/EMTDS, which is inspired from an operational microgrid in Goldwind Sc. Tech. Co. Ltd, in Beijing, China. The results showed great level of effectiveness to accurately identify faults from other non-fault disturbances, precisely locate the fault and trigger opening of the right circuit breaker/s under different operation modes, fault resistances and other system disturbances.

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A New Solution to Coulomb Friction in Mechanism Bearings: Theory and Application

Journal of Mechanical Design ◽

10.1115/1.3254986 ◽

1981 ◽

Vol 103 (4) ◽

pp. 764-775 ◽

Cited By ~ 4

Author(s):

I. Imam ◽

M. Skreiner ◽

J. P. Sadler

Keyword(s):

Coulomb Friction ◽

Circuit Breaker ◽

Closed Form Solution ◽

Form Solution ◽

Design Tool ◽

Operating Conditions ◽

Equilibrium Equations ◽

Simplified Approach ◽

Novel Approach ◽

In Series

A new approximate closed form solution is presented for analyzing Coulomb friction in mechanism bearings. This is accomplished by linearizing the nonlinear terms of the equilibrium equations by a novel approach. The method, based on the traditional friction circle concepts, is particularly well suited to computers and proceeds to the solution without the need for any numerical methods or iterative steps as has previously been required. Further, only a pair of simultaneous equations is solved at a time, thus eliminating the need for a complete matrix inversion. It is believed that this simplified approach will be more readily usable in actual design situations where consideration of bearing friction is of considerable importance. A number of analytical validity checks were applied that successfully verified the adequacy of this new approach. As an example, the theory is applied to various models of a class of circuit breaker mechanisms, consisting of five four-bar linkages in series under different operating conditions. In all cases, the analytical results compare very favorably with the test data, thus establishing the method as a valuable practical design tool.

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Copper-dependent ATP7B up-regulation drives the resistance of TMEM16A-overexpressing head-and-neck cancer models to platinum toxicity

Biochemical Journal ◽

10.1042/bcj20190591 ◽

2019 ◽

Vol 476 (24) ◽

pp. 3705-3719 ◽

Cited By ~ 2

Author(s):

Avani Vyas ◽

Umamaheswar Duvvuri ◽

Kirill Kiselyov

Keyword(s):

Oxidative Stress ◽

Head And Neck ◽

Transcriptional Activation ◽

Platinum Resistance ◽

Mrna Levels ◽

Strong Positive Correlation ◽

Platinum Compounds ◽

Copper Chelation ◽

Novel Approach ◽

Cancer Models

Platinum-containing drugs such as cisplatin and carboplatin are routinely used for the treatment of many solid tumors including squamous cell carcinoma of the head and neck (SCCHN). However, SCCHN resistance to platinum compounds is well documented. The resistance to platinum has been linked to the activity of divalent transporter ATP7B, which pumps platinum from the cytoplasm into lysosomes, decreasing its concentration in the cytoplasm. Several cancer models show increased expression of ATP7B; however, the reason for such an increase is not known. Here we show a strong positive correlation between mRNA levels of TMEM16A and ATP7B in human SCCHN tumors. TMEM16A overexpression and depletion in SCCHN cell lines caused parallel changes in the ATP7B mRNA levels. The ATP7B increase in TMEM16A-overexpressing cells was reversed by suppression of NADPH oxidase 2 (NOX2), by the antioxidant N-Acetyl-Cysteine (NAC) and by copper chelation using cuprizone and bathocuproine sulphonate (BCS). Pretreatment with either chelator significantly increased cisplatin's sensitivity, particularly in the context of TMEM16A overexpression. We propose that increased oxidative stress in TMEM16A-overexpressing cells liberates the chelated copper in the cytoplasm, leading to the transcriptional activation of ATP7B expression. This, in turn, decreases the efficacy of platinum compounds by promoting their vesicular sequestration. We think that such a new explanation of the mechanism of SCCHN tumors’ platinum resistance identifies novel approach to treating these tumors.

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Collecting Words: A Clinical Example of a Morphology-Focused Orthographic Intervention

Language Speech and Hearing Services in Schools ◽

10.1044/2020_lshss-19-00050 ◽

2020 ◽

Vol 51 (3) ◽

pp. 544-560 ◽

Cited By ~ 3

Author(s):

Kimberly A. Murphy ◽

Emily A. Diehm

Keyword(s):

Written Language ◽

Morphological Knowledge ◽

English Orthography ◽

Word Level ◽

Novel Approach ◽

Language Pathology ◽

The One ◽

Critical Intervention ◽

Reading And Spelling ◽

Reading And Spelling Difficulties

Purpose Morphological interventions promote gains in morphological knowledge and in other oral and written language skills (e.g., phonological awareness, vocabulary, reading, and spelling), yet we have a limited understanding of critical intervention features. In this clinical focus article, we describe a relatively novel approach to teaching morphology that considers its role as the key organizing principle of English orthography. We also present a clinical example of such an intervention delivered during a summer camp at a university speech and hearing clinic. Method Graduate speech-language pathology students provided a 6-week morphology-focused orthographic intervention to children in first through fourth grade ( n = 10) who demonstrated word-level reading and spelling difficulties. The intervention focused children's attention on morphological families, teaching how morphology is interrelated with phonology and etymology in English orthography. Results Comparing pre- and posttest scores, children demonstrated improvement in reading and/or spelling abilities, with the largest gains observed in spelling affixes within polymorphemic words. Children and their caregivers reacted positively to the intervention. Therefore, data from the camp offer preliminary support for teaching morphology within the context of written words, and the intervention appears to be a feasible approach for simultaneously increasing morphological knowledge, reading, and spelling. Conclusion Children with word-level reading and spelling difficulties may benefit from a morphology-focused orthographic intervention, such as the one described here. Research on the approach is warranted, and clinicians are encouraged to explore its possible effectiveness in their practice. Supplemental Material https://doi.org/10.23641/asha.12290687

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