1,401 research outputs found
A historical comment about the GVT in short interval
No full textIn this article, the author introduces the history, progress and method in the Goldbach-Vinogradov Theorem in short interval by which every sufficiently large odd integer could be expressed as the sum of three almost equal prime numbers.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000183488400018&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701MathematicsCPCI-S(ISTP)
Investigation on the DC CB Performance during a Current Interruption Failure at First Current Zero
No full textThe vacuum interrupter is used as the key component of an active DCCB due to its excellent interruption and dielectric recovery characteristics after current zero. The vacuum interrupter can only interrupt the fault currents below the limitation of a critical di/dt and TIV, otherwise it causes a reignition and the interruption failure. In this paper, a detailed active injection DC CB model is developed, considering operation delay of switches, parasitic parameters of switches and thorough control logic. The limitation dielectric strength between the vacuum gap is defined by the cold break down voltage. Based on the numerical modelling, investigation will be performed to see the performance of DC CB with a failure interruption on the first current zero. The simulation results can help to optimize the injection circuit parameters when DC CB has a failure on the first current zero and has to interrupt in the next current zeros. This algorithm will consider predefined threshold of di/dt, chopping current and variable operation time in different scenarios.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Intelligent Electrical Power Grid
Technical performance of different DC CB technologies for future HVDC Grids
No full textMultiterminal dc (MTDC) network is preferred due to its reliability, security of supply and flexibility. However, MTDC network also comes with the protection challenges resulting from dc faults. Hence, the dc circuit breaker (DC CB) is imperative in such a network. In these recent years, several DC CB technologies have been proposed and demonstrated by different manufacturers. Besides, these DC CB technologies differ from each other in terms of the speed of operation, interruption capability and costs. Hence, for the optimal performance of the MTDC network, a study of the co-ordinative operation of different DC CB technologies is required. In this thesis, two typical types of DC CBs are modelled in detail and implemented in a 4-terminal MTDC network in PSCAD environment, by considering operation time, interruption capability and interruption characteristics. The obtained results are used for DC CB’s selection optimization methodology for the future MTDC networks. Similarly, a scaled model of DC CB has to be analysed in terms of its interruption capability in MTDC network considering various scenarios. Therefore, in this master thesis, technical performance of DC CB technologies is conducted for a test and multiterminal dc network in EMT based software environment.The DC CB is the key to unlock the reliable operation of a Multi-terminal direct current network, whereas fast, effective and accurate models are frequently needed for system-level studies. Due to higher subsystem components in DC CB, a detailed DC CB model creates a bottleneck in the network analysis. This thesis also proposes and compares, an average model with a detailed model of Voltage source converter Assisted Resonant Current (VARC) and Mechanical DC CB in MTDC Network in terms of their performance and computation time for two typical simulation cases. The average and detailed model is modelled and simulated on the PSCAD/EMTDC electromagnetic transient platform. Decisively, this thesis concludes by presenting an accurate response of the average model during the fast transient event, showing additional computational advantage.<br/
The characteristics of the polish CB-language
No full textThe paper analyzes the language used by drivers on the Citizens’ Band radio (CB radio). The
users of the radio communicate only in speech, their communication is highly pragmatic and
based on partnership. The utterances alternate between formal and informal ones, which
determines the range and register of vocabulary. Drivers often use diminutives and polite
addresses thus creating the atmosphere of mutual respect and cordiality, which can be
comforting and reassuring for strangers who happen to establish a casual contact. The specific
language used on the CB radio fulfils two basic functions: it creates a sense of community
among drivers and protects the information passed on as warnings. At the end of the paper,
the author appends a comprehensive glossary of the CB language
Modelling of GO/PPy/CB and rGO/PPy/CB nanocomposite supercapacitors using an electrical equivalent circuit
No full textIn this study, supercapacitor device performances of graphene oxide (GO), reduced graphene oxide (rGO), polypyrrole (PPy), and ternary nanocomposites of GO, PPy, and carbon black (CB) as GO/PPy/CB and rGO/PPy/CB were firstly prepared using the in situ polymerization method. The obtained composite materials were characterized by scanning electron microscopy energy–dispersive X-ray (SEM–EDX), Fourier-transform infrared-attenuated transmission reflectance (FTIR-ATR), X-ray diffraction (XRD), thermal gravimetric analysis (TGA), atomic force microscopy (AFM), Brunauer–Emmett–Teller (BET) surface area analysis, cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopic (EIS) methods. The highest specific capacitance (Csp) of the rGO/PPy/CB nanocomposite was obtained as Csp = 39, 48, and 27.86 F × g?1 by three methods of CV, GCD, and EIS, respectively. Two equivalent circuit models of Rs(CdlRct) and LRs(QRct) were presented to compare equivalent circuit parameters. Theoretical and experimental values are compatible with each other. Graphical abstract: [Figure not available: see fulltext.]. © 2021, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.Trakya ÜniversitesiThis work is a part of the research project NKUBAP.01.?NAP.19.213 approved by the Scientific and Research Project Unit (Tekirdag Namik Kemal University). This research grant is gratefully acknowledged. We thank Prof. Dr. Murat Turkyilmaz and Ozan Yoruk (PhD student) for TGA and BET measurements (TUTAGEM, Trakya University, Turkey)
„Misiek z okularami na hulajnodze”, czyli o CB-polszczyźnie
No full textThe paper analyzes the language used by drivers on the Citizens’ Band radio (CB radio). The users of the radio communicate only in speech, their communication is highly pragmatic and based on partnership. The utterances alternate between formal and informal ones, which determines the range and register of vocabulary. Drivers often use diminutives and polite addresses thus creating the atmosphere of mutual respect and cordiality, which can be comforting and reassuring for strangers who happen to establish a casual contact. The specific language used on the CB radio fulfils two basic functions: it creates a sense of community among drivers and protects the information passed on as warnings. At the end of the paper, the author appends a comprehensive glossary of the CB language
Fast bug finding in lock-free data structures with CB-DPOR
No full textThesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2014.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student-submitted PDF version of thesis.Includes bibliographical references (pages 39-40).This thesis describes CB-DPOR, an algorithm for quickly finding bugs in lock-free data structures. CB-DPOR is a combination of the CHESS and DPOR model checking algorithms. CB-DPOR performs similar to the concurrently developed preemption-bounded BPOR algorithm. CODEX is a tool for finding bugs in lock-free data structures. CODEX implements CBDPOR and this thesis demonstrates how to use CODEX to find bugs. This thesis describes new bugs in open-source lock-free data structures, and compares the performance of CBDPOR with the earlier model checking algorithms CHESS, DPOR, and PCT. CB-DPOR find bugs one to two orders of magnitude faster than earlier algorithms.by Jelle van den Hooff.M. Eng
Characterization of [nickel(cyclam)] CB[8] as an outer-sphere redox agent
No full textLong-range electron transfer reactions play a key role in the life-giving processes of photosynthesis and respiration; however, much is still unknown about electron transfer occurring over extended distances. The focus of this project is to design and study synthetic systems in which electron transfer will be forced to take place over larger than normal distances due to steric bulk surrounding a redox active metal centre. Two approaches are followed – (1) complexing bulky pendant arm macrocycles with redox active metals and (2) encapsulating a redox active metal macrocycle within a bulky host molecule—cucurbit[8]uril.The metal pendant arm macrocycles proved to be insoluble in aqueous solutions, excluding them from kinetic studies. The inclusion complex, [Ni(cyclam)]@CB[8], however, is water-soluble at the low concentrations needed for kinetic analysis. Furthermore, the inclusion complex is readily oxidized to the nickel(III) form by the oxidant hexaaquacobalt(III). Upon oxidation, the [NiIII (cyclam)]@CB[8] complex can be used as an oxidant for the benzenediols, hydroquinone and catechol. The results of the above kinetic studies can be directly compared to previous studies involving free NiII(cyclam) as the reductant/oxidant. In this way, the steric effect of the bulky cucurbit[8]uril ring on the rate of electron transfer can be directly accounted for. The results indicate that encapsulation of the Ni(II) macrocycle within cucurbit[8]uril results in a factor of 2 decrease in the rates of electron transfer as compared to that of the free Ni(II) macrocycle. This indicates that steric bulk has a significant effect on the rate of electron transfer, as expected.A novel "one-pot" synthesis of the inclusion complex [Ni(cyclam)]@CB[8], as well as the crystal structure of [Cu(cyclam)]@CB[8], showing cyclam in the rare trans-I configuration, will also be reported.Source: Masters Abstracts International, Volume: 47-06, page: 3601
23.5 A Sub-1V 810nW Capacitively-Biased BJT-Based Temperature Sensor with an Inaccuracy of ±0.15°C (3σ) from -55°C to 125°C
No full textBJT-based temperature sensors are widely used because they can achieve excellent accuracy after 1-point calibration. However, they typically dissipate mu textWs of power and require supply voltages above 1V [1]. Although sensors based on DTMOSTs [2], [3], capacitively biased (CB) diodes and BJTs [4,5] have demonstrated sub-1V operation, this comes at the expense of accuracy. This paper presents a sub-1V CB BJT-based temperature sensor that achieves a 1-point-trimmed inaccuracy of 0.15°C (3σ) from -55 circC to 125 circC, which is 4times better than the CB BJT state-of-the-art [4]. It also achieves a resolution FoM of 0.34pJ.K2, which is 6.8 times better than that of state-of-the-art BJT-based sensors with a similar accuracy [1], [6], (Fig. 23.5.6).Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic InstrumentationMicroelectronic
Modeling, Experimental Validation, and Application of VARC HVDC Circuit Breakers
No full textThis paper deals with the modeling, hardware results and model validation by measurements of a VSC assisted resonant current (VARC) dc circuit breaker (CB) and the application within a future network by simulation. The newly emerging VARC dc CB can be used as a solution for the protection of offshore multi-terminal HVDC (MTDC) grids. In this paper, the proposed VARC dc CB is modeled in detail in a PSCAD environment, by taking into account dielectric strength of the vacuum gap, high-frequency current quenching ability and parasitic components. The PSCAD-model is then verified by data from the testing of a 27 kV VARC dc CB prototype with maximum current interruption capability of 10 kA. Additionally, the initial transient interruption voltage and current slope at zero-crossing during the interruption are analyzed. With respect to scaling to a higher voltage level, three types of series connected modules are presented and the performances are compared. The performance of the series connected modules is simulated in a model of a 4-terminal HVDC grid. The obtained results validate the VARC dc CB as a promising solution for the dc fault isolation in MTDC grids.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Intelligent Electrical Power Grid
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