scholarly journals Strain localisation and failure at twin-boundary complexions in nickel-based superalloys

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Zhenbo Zhang ◽  
Zhibiao Yang ◽  
Song Lu ◽  
Allan Harte ◽  
Roberto Morana ◽  
...  

Abstract Twin boundaries (TBs) in Ni-based superalloys are vulnerable sites for failure in demanding environments, and a current lack of mechanistic understanding hampers the reliable lifetime prediction and performance optimisation of these alloys. Here we report the discovery of an unexpected γ″ precipitation mechanism at TBs that takes the responsibility for alloy failure in demanding environments. Using multiscale microstructural and mechanical characterisations (from millimetre down to atomic level) and DFT calculations, we demonstrate that abnormal γ″ precipitation along TBs accounts for the premature dislocation activities and pronounced strain localisation associated with TBs during mechanical loading, which serves as a precursor for crack initiation. We clarify the physical origin of the TBs-related cracking at the atomic level of γ″-strengthened Ni-based superalloys in a hydrogen containing environment, and provide practical methods to mitigate the adverse effect of TBs on the performance of these alloys.

2017 ◽  
Vol 19 (32) ◽  
pp. 21648-21654 ◽  
Author(s):  
Trinh Thi Ly ◽  
Ganbat Duvjir ◽  
Taewon Min ◽  
Jinho Byun ◽  
Taehoon Kim ◽  
...  

The alloying behavior of crystalline SnSe1−xSx was investigated at the atomic level by combining STM experiments and DFT calculations.


2021 ◽  
Author(s):  
◽  
Katherine Smith

<p>Within the literature associated with political leadership, scholarship directly focused upon political performance in office is thinly conducted, both in New Zealand and in other areas across the world. This thesis aims to greater understand political leadership and performance in New Zealand, and address the gaps in the literature correlated with Prime Ministerial performance. To do this, this thesis provides a current list of rankings of former Premiers and Prime Ministers in New Zealand and identifies the dimensions that one must fulfil to display exceptional performance in office. To undertake this research, this thesis uses a series of surveys – distributed to students at Victoria University of Wellington, and to other individuals with a professional interest in politics and history in New Zealand – to best assess public perceptions towards political performance. Building upon the path dependency created by former exercises of the same nature in New Zealand (conducted by Simon Sheppard in 1998, and by Jon Johansson and Stephen Levine in 2011), this thesis provides a snapshot of the current public perceptions of outstanding political performance. In a similar nature to the earlier studies, this thesis identifies the dimensions of longevity, death in office, and being a ‘big change’ or crisis Prime Minister as being directly correlated with elevated performance in office. Additionally, this thesis investigates whether a series of variables – namely time between exercises in New Zealand, and the appearance of a possible recency effect– provide any influence or change over results. Additionally, this thesis moves outside the scope of exercises conducted previously in New Zealand, by ranking Prime Ministerial performance using a series of different methodologies. In conjunction with a replication of the exercises already conducted in New Zealand, this survey also assesses Prime Ministerial performance by using a survey based upon the well-cited Schlesinger ranking studies in the United States, and a third survey aimed to assess political shifts and levels of knowledge and recall rates amongst university students. Regardless of such factors, the results of this thesis remain consistent with previous exercises, with Michael Savage, Richard Seddon, Helen Clark and Peter Fraser being regarded by the political and academic elite across all surveys as embodying the highest qualities of successful political leadership in New Zealand.</p>


2012 ◽  
Vol 533 ◽  
pp. 43-49 ◽  
Author(s):  
Benoît Ter-Ovanessian ◽  
Dominique Poquillon ◽  
Jean-Marc Cloué ◽  
Eric Andrieu

Author(s):  
Milija Gluhovic ◽  
Silvija Jestrovic ◽  
Shirin Rai ◽  
Michael Saward

Beginning with two vivid examples that illustrate the Handbook’s core arguments—that politics is performative, performance is political, and that both of these matter to understanding our worlds—the introduction provides a current, contextual account of the shared syntax of politics and performance. It defines key terms, such as politics, performance, theatricality, and performativity, that inform the Handbook contributions. Through accessible and provocative engagements with new ways of thinking about politics and performance in both disciplinary and interdisciplinary modes, the introduction shows that these categories are interwoven and entangled in complex and consequential ways. It outlines the states of the art in theater and performance studies and politics, respectively, capturing key points of interconnection between these discourses in order to build on, extend, and reshape interdisciplinary conversations. Finally, it reflects on key challenges and opportunities that attend bringing the two broad fields together for mutual enrichment and building a new, hybrid field of study. Underlining the co-constitutive nature of performance and politics, the introduction suggests that such a framework is critical to promoting an interdisciplinary approach to understanding the complex political world of the twenty-first century.


2020 ◽  
Vol 999 ◽  
pp. 13-20
Author(s):  
Qing Wu Zhang ◽  
Tian Fang ◽  
Hao Lu ◽  
Wei Wang ◽  
Qing Qing Zhang ◽  
...  

Protein gel of soy was formed immediately during polymerization of aniline initiated by certain amount of FeCl3. In order to obtain iron-doped carbon material, this composite was then carbonized at 700°C under nitrogen atmosphere for 5h. SEM, FT-IR, XRD, and isothermal desorption/adsorption technologies were employed to characterize morphology and structure of the material. Electrical capacitance of iron-doped carbon materials and performance of a prototype supercapacitor based on the material as its electrodes were measured by cyclic voltammetry, chronopotentiometry, and A.C. impedance respectively. Results show that morphology of as-obtained material is porous and hierachical, specific surface area of the material is 232.1m2/g, and specific capacitance of the material can reach 475.2F/g in 6 M KOH aqueous solution. Energy density and power density of the cell is 2.1Wh/kg and 2.0kW/kg, respectively. Capacity retention of the device is 100% after 5000 cycles at a current density of 2A/g. The above studies imply that this original iron-doped carbon material will have a good potential application in field of energy storage.


2001 ◽  
Vol 11 (1) ◽  
pp. 2114-2117 ◽  
Author(s):  
K. Sasaki ◽  
A. Yamagata ◽  
A. Nii ◽  
T. Onishi ◽  
M. Shibuya

Author(s):  
Samuel Kanner ◽  
Ronald W. Yeung

The possibility of incorporating a wave-energy extractor into a current design of the WindFloat platform is examined. First, to absorb wave energy, a rolling cam shape, with rotary power take-off, is attached to a tubular truss member of the WindFloat located above the calm-waterline. Based on the assumption that the extractor is operating in beam seas, numerical predictions for the coupled 3-DOF system (surge, heave and pitch motions) were completed for an ideal-fluid situation. The degradation of the performance of the wave energy extractor because of viscous effects was discussed in [1]. Second, a design of a versatile bi-directional rotary system, named the UC Berkeley Double-Ratchet Mechanism (UCB-DRM) was made. This mechanism can produce a unidirectional rotational motion, thus facilitating the power take off by a generator. A physical unit was constructed. The efficiency and performance of this mechanical system is assessed by introducing a known, bi-directional torque input and measuring the torque output.


2015 ◽  
Vol 40 (1) ◽  
pp. 83-87 ◽  
Author(s):  
ALYSON CAMPBELL ◽  
STEPHEN FARRIER

This short piece highlights a current spurt in queer researcher–practitioners doing practice as research (PaR) in higher education and explores potential reasons why PaR is so vital, appealing, useful and strategic for queer research. As a starting point, we offer the idea of messiness and messing things up as a way of describing the methods of PaR. Queer mess is to do with asserting the value and pleasure of formations of knowledge that sit outside long-standing institutional hierarchies of research. The latter places what Robin Nelson calls ‘hard knowledge’ above tacit, quotidian, haptic and embodied knowledge. The methodological and philosophical impulses of PaR make space for a range of research methods inherently bound up with the researcher as an individual and the materiality of lived experience within research. Yet, in our experience, although each PaR project is individual, PaR projects follow certain shared modes evolving largely from embodied and heuristic research methods adapted from social sciences, such as (auto)ethnography, participant observation, phenomenology and action research. PaR methodology in theatre and performance is composed of a bricolage of these openly embodied methods, which makes PaR, as an embodied resistance to sanitary boundaries, somewhat queer in academic terms already. It is unsurprising, then, that PaR is so attractive to queer practitioner–researchers bent on queering normative hierarchies of knowledge.


2012 ◽  
Vol 241-244 ◽  
pp. 632-635
Author(s):  
H. L. Do

In this paper, an energy recovery for plasma display is proposed. The proposed energy recovery sustainer provides soft-switching of main sustain switches and reduces the switching loss. Due to soft-switching characteristic, the switching losses of main switches are significantly reduced. In addition, the conduction losses in both main and auxiliary switches are effectively reduced by varying a current build-up time according to image patterns. Theoretical analysis and performance of the proposed energy recovery sustain driver were verified on an experimental prototype operating at 200 kHz switching frequency.


2007 ◽  
Vol 19 (24) ◽  
pp. 1961-1963 ◽  
Author(s):  
Da-Long Cheng ◽  
Tsu-Chiang Yen ◽  
Wei Chang ◽  
Wang-Chuang Kuo ◽  
Kuo-Sheng Kao ◽  
...  

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