Academic literature on the topic 'SNL fuel assembly'

In this present work, a systematically study on 20% PtCeO2/C catalyst for ethanol electro-oxidation in direct ethanol fuel cell were carried out. For cathode catalyst, a commercial catalyst of 40% Pt/C from ETEK was applied. Catalysts were printed on to carbon paper of TGPH 060 and sandwiched into membrane electrode assembly (MEA) and then arranged infitel cell with the geometric area 1.2 cm2. As an electrolyte, we used Nafion 117 from Du Pont. On-line Differential Electrochemical Mass Spectrometry (DEMS) measurement infuel cell setup was carried out in order to determine the activity and selectivity which was indicated by result of Faradaic current and CO2 current efficiency of ethanol electro-oxidation respectively. PtCeO2/C was significantly improving the selectivity of CO formation n comparison to the commercial catalyst of 20% Pt/C from A/fa Aesar- Johnson Mattews. Increasing of" selectivity was shown by the increase of CO2 current efficiency of ethanol oxidation of about 20 percent in comparison to references catalyst of 20% Pt/C (AlfaAesar-JM).Keywords: Ceria, Membrane Electrode Assembly (MEA), DEMS, Ethanol Electro-OxidationAbstrakPada peneletian ini dilakukan kajian sistematis terhadap katalis 20% PtCeO2/C yang akan digunakan pada elektro-oksidasi etanol pada sel bahan bakar etanol langsung. Untuk katalis katoda, digunakan katalis komersial 40% Pt/C dari ETEK. Katalis tersebut diaplikasikan pada kertas karbon TGPH 060 dan diselipkan pada rangkaian membran electroda (MEA) dan kemudian disusun pada sel bahan bakar yang memiliki luas geometris 1.2 cm2. Sebagai elektrolit, digunakan Nafion 117 produksi Du Pont. Pengukuran On-line oleh Spektrometri Massa Elektrokimia Diferensial atau Differential Electrochemical Mass Spectrometry (DEMS) pada pemasangan sel bahan bakar telah dilakukan untuk menentukan aktivitas dan selektivitasnya yang dapat ditunjukkan masing-masing oleh hasil arus Faradik dan efisiensi arus CO2 dari elektro-oksidasi etanol. Dari hasil percobaan diperoleh bahwa PtCeO2/C dapat secara signifikan meningkatkan selektivitas untuk membentuk CO2 dibandingkan terhadap katalis komersial 20% Pt/C dari A/fa Aesar-Johnson Mattews. Kenaikan selektivitas ditunjukkan oleh kenaikan efisiensi arus CO2pada oksidasi ethanol sebesar 20 persen dibandingkan terhadap katalis rujukan 20% Pt/C (AlfaAesar-JM).Kata Kunci: Ceria, Membrane Electrode Assembly (MEA), DEMS, Elektro-Oksidasi Etanol

The neutron-physical characteristics of curium and americium in spent nuclear fuel (SNF) of the BN-600 reactor were considered in the work. With the help of the Serpent software complex, several models of the BN-600 reactor fuel assembly with different enrichment of fuel by U-235 were built. In BN-600, with the probability of dividing Am-241 by no more than 15%, incomplete burning of minor actinides (MA) occurs and even the accumulation of Cm-244, which is dangerous for storage.

The purposes of this research are designing the prototype of DMFC, consist of graphite and aluminium cell stacks and MEA with difference Nafion content. Cell stack has active area of 6.5 cm2, and single serpentine flow field. MEAs were fabricated using Nafion membrane 117 (DuPont), gas diffusion layer (GDL) carbon cloth, and commercial catalysts E-Tek, Pt/C for the cathode side and Pt-Ru/C for the anode. Catalysts loading on the anode are 3 and 4 mgPt-Ru/cm2 and on the cathode is 3 mg/cm2. Dry Nafion content of 20 %-wt and 40 %-wt were used in this experiment. MEA fabrication was done by brush coating and hot pressing. Single cell test conducted to evaluate the performance of DMFC at 70°C with 2M methanol as fuel and air as the oxidant. The results of single cell test showed that cell voltage of 600-750 mV, current density of 100 150 mW/cm2, with maximum power density of 19 mW/cm2 ware achieved. MEA with 40 wt% Nafion content showed the better performance than 20 %-wt with power density 19 mWlcm2 and 6 mW/cm2, respectively. Increasing the catalyst loading from 3 to 4 mgPt-Ru/cm2 improved the power density from 16 to 18 mW/cm2. Keywords: Direct Methanol Fuel Cell, Cel stack, MEA, Nation content. Abstrak Penelitian ini bertujuan untuk merancang sebuah prototipe DMFC dengan cell stack berbahan grafit dan aluminium serta fabrikasi MEA dengan variasi kandungan Nafion. Cell stack memiliki luas aktif 6.5 cm2 dengan flowfield bertipe single serpentine. MEA difabrikasi menggunakan membran Nafion 117 (DuPont), lapisan difusi gas carbon cloth dan katalis komersial E-Tek, Pt/C untuk katoda dan Pt-Ru/Cuntuk anoda. Kandungan katalis adalah 3 dan 4 mgPt-Ru/cm2 pada sisi anoda dan 3 mg/cm2 pada sisi katoda. Kandungan Nafion yang digunakan adalah 20 dan 40 % berat. Fabrikasi MEA dilakukan dengan metode brush coating dan hot pressing. Uji kinerja DMFC dilakukan pada suhu 70°C dengan menggunakan bahan bakar metanal 2M dan udara sebagai oksidan. Hasil uji kinerja DMFC sel tunggal didapatkan potensial sel 600-750 mv densitas arus 100-150 mW/cm serta densitas energi maksimum 19 mW/cm2. MEA dengan kandun?an Nafion 40 % berat memiliki kinerja yang lebih baik dengan densitas energi 19 mW/cm dibandingkan dengan Nafion 20 % berat sebesar 6 mW/cm2. Kenaikan loading katalis anoda dari 3 menjadi 4 mgPt-Ru/cm2 dapat meningkatkan densitas energi dari 16 mW/cm2 menjadi 18 mW/cm2.Kata kunci: Direct Methanol Fuel Cell,Cel stack, MEA, kandungan Nation.

Abstract Key steps in hematopoiesis and the expression of genes encoding hemoglobin subunits are critically dependent upon specific members of the GATA factor family of transcription factors. Our recent efforts have focused on elucidating how GATA factors select functional sites in chromatin and how they function combinatorially with additional regulatory factors. GATA motifs are often arranged in close proximity to E-boxes, and such composite elements commonly mediate GATA factor- and Scl/TAL1-dependent transcriptional responses. Only a small fraction of these composite elements in chromatin are occupied by GATA factors and Scl/TAL1, and a specific epigenetic signature distinguishes occupied versus unoccupied elements genome-wide. In the context of hemoglobin synthesis, we are using genetic and molecular approaches to dissect the multistep mechanism underlying the control of β-globin transcription. GATA-1-containing complexes assemble at the β-globin Locus Control Region (LCR) prior to the murine adult βmajor promoter. Though the LCR physically interacts with the βmajor promoter, this interaction is not required for the binding of several trans-acting factors to the LCR or the promoter. A hypomorphic mutation of the chromatin remodeler BRG1 limits the extent to which RNA Polymerase II (Pol II) is recruited to the promoter and also abrogates the LCR-promoter interaction. Whereas looping is not required for assembly of the full complement of promoter complex components, looping is linked to the establishment of maximal levels of Pol II at the promoter. Collectively, these results provide insights into the relationship between, and importance of, individual steps in the multi-step activation mechanism. I will discuss progress on unraveling mechanisms underlying GATA-1-mediated activation of the adult β-like globin genes as well as fundamental aspects of GATA factor function, which have broad relevance in diverse systems. promoter. Though the LCR physically interacts with the β promoter, this interaction is not required for the binding of several -acting factors to the LCR or the promoter. A hypomorphic mutation of the chromatin remodeler BRG1 limits the extent to which RNA Polymerase II (Pol II) is recruited to the promoter and also abrogates the LCR-promoter interaction. Whereas looping is not required for assembly of the full complement of promoter complex components, looping is linked to the establishment of maximal levels of Pol II at the promoter. Collectively, these results provide insights into the relationship between, and importance of, individual steps in the multi-step activation mechanism. I will discuss progress on unraveling mechanisms underlying GATA-1-mediated activation of the adult β-like globin genes as well as fundamental aspects of GATA factor function, which have broad relevance in diverse systems.

Asymmetric gas diffusion media (GDM) pairing, which feature distinct GDM at the anode and cathode of the proton electrolyte membrane fuel cell (PEMFC), enhance water management compared to symmetric pairing of GDM (anode and cathode GDM are identical). An asymmetric pairing of Freudenberg GDM (H24C3 at anode and H23C2 at cathode) reduces ohmic resistances by up to 40% and oxygen transport resistances by 14% en route to 25% higher current density in dry gas flows. The asymmetric GDM pairing effectively hydrates the membrane electrode assembly (MEA) while minimizing liquid water saturation in the cathode compared to a commonly used symmetric GDM pairing of SGL 29BC at the anode and cathode. Superior water management observed with asymmetric GDM in flow-through mode is also realized in dead-ended anode (DEA) mode. Compared to the symmetric GDM pairing, the asymmetric GDM pairing with Freudenberg GDM increases cell voltage at all current densities, extends and stabilizes steady-state voltage behavior, slows voltage decay, and vastly reduces the frequency of anode purge events. These results support that the asymmetric Freudenberg GDM combination renders the PEMFC less prone to anode water saturation and performance loss from the anticipated increase in water back-diffusion during DEA mode operation.

The Cs2SnX6 perovskites have attracted much attention due to excellent optoelectronic properties and high stability. In the present work, we have focused on the morphology control and photoluminescence characteristics of the Cs2SnCl6 perovskite crystals. The synthesis process of the Cs2SnCl6 crystals includes two stages composed of the formation of initial crystals and the growth of Cs2SnCl6; the later originated from the oxidization of CsSnCl3. This process has been confirmed by Scanning electron microscope (SEM) and X-rays diffraction (XRD). By controlling the concentration of the initial reactants and hydrochloric acid in the solution to change the supersaturation of the solution, different crystal morphologies, such as truncated octahedron, octahedron, hexapod, quasi-sphere, have been obtained. In relatively a low supersaturation solution, the amount of growth units dominates the crystal growth process to obtain the hexapod and self-assembly crystals. In contrast, in relatively high supersaturation solution, nucleation predominates to yield small size truncated octahedrons and near-spherical Cs2SnCl6 crystals. The synthesized Cs2SnCl6 crystals have shown a wide emission band peaking at 450 nm with full width at half maximum (FWHM) 63 nm due to the defects introduced by Sn2+. The photoluminescence intensities of crystals synthesized at various conditions exhibited considerable difference, which was about 60 times between the highest and the lowest.

Facilitating the uptake of established methodologies for risk-based decision-making in product conformity assessment taking into account measurement uncertainty by providing dedicated software is the aim of the European project EMPIR CASoft(2018–2020), involving the National Measurement Institutes from France, Sweden and the UK, and industrial partner Trescal (FR) as primary supporter. The freely available software helps end-users perform the required risk calculations in accordance with current practice and regulations and extends that current practice to include bivariate cases. The software is also aimed at supporting testing and calibration laboratories in the application of the latest version of the ISO/IEC 17025:2017 standard, which requires that“…the laboratory shall document the decision rule employed, taking into account the level of risk […] associated with the decision rule and apply the decision rule.” Initial experiences following launch of the new software in Spring 2020 are reported.

ComplexinII (CpxII) inhibits non-synchronized vesicle fusion, but the underlying mechanisms have remained unclear. Here, we provide evidence that the far C-terminal domain (CTD) of CpxII interferes with SNARE assembly, thereby arresting tonic exocytosis. Acute infusion of a CTD-derived peptide into mouse chromaffin cells enhances synchronous release by diminishing premature vesicle fusion like full-length CpxII, indicating a direct, inhibitory function of the CTD that sets the magnitude of the primed vesicle pool. We describe a high degree of structural similarity between the CpxII CTD and the SNAP25-SN1 domain (C-terminal half) and show that the CTD peptide lowers the rate of SDS-resistant SNARE complex formation in vitro. Moreover, corresponding CpxII:SNAP25 chimeras do restore complexin’s function and even ‘superclamp’ tonic secretion. Collectively, these results support a so far unrecognized clamping mechanism wherein the CpxII C-terminus hinders spontaneous SNARE complex assembly, enabling the build-up of a release-ready pool of vesicles for synchronized Ca2+-triggered exocytosis.

Content warning: although it was kept to a minimum, this text displays instances of (anti-Semitic) hate speech. During the 2016 U.S. election and its aftermath, multiple journalistic accounts reported on “alt-right trolls” emanating from anonymous online spaces like the imageboard 4chan (e.g. Abramson; Ellis). Having gained infamy for its nihilist trolling subcultures (Phillips, This Is Why) and the loose hacktivist movement Anonymous (Coleman), 4chan now drew headlines because of the alt-right’s “genuinely new” concoction of white supremacy, ironic Internet humour, and a lack of clear leadership (Hawley 50). The alt-right “anons”, as imageboard users call themselves, were said to primarily manifest on the “Politically Incorrect” subforum of 4chan: /pol/. Gradually, a sentiment arose in the titles of several news articles that the pro-Trump “alt-right trolls” had successfully won the metapolitical battle intertwined with the elections (Phillips, Oxygen 5). For instance, articles titled that “trolls” were “The Only True Winners of this Election” (Dewey) or even “Plotting a GOP Takeover” (Stuart).The headlines were as enticing as questionable. As trolling-expert Whitney Phillips headlined herself, the alt-right did not attain political gravity solely through its own efforts but rather was “Conjured Out of Pearl Clutching and Media Attention” (“The Alt-Right”), with news outlets being provoked to criticise, debunk, or sensationalise its trolling activities (Faris et al. 131; Phillips, “Oxygen” 5-6). Even with the right intentions, attempts at denouncement through using vague, structuralist notions–from “alt-right” and “trolls” to “the basket of deplorables” (Robertson) – arguably only strengthened the coherence of those it was meant to disavow (Phillips, Oxygen; Phillips et al.; Marantz). Phillips et al. therefore lamented such generalisations, arguing attributing Trump’s win to vague notions of “4chan”, “alt-right”, or “trolls” actually bestowed an “atemporal, almost godlike power” to what was actually an “ever-reactive anonymous online collective”. Therefore, they called to refrain from making claims about opaque spaces like 4chan without first “plotting the landscape” and “safeguarding the actual record”. Indeed, “when it comes to 4chan and Anonymous”, Phillips et al. warned, “nobody steps in the same river twice”.This text answers the call to map anonymous online groups by engaging with the complexity of testing the muddy waters of the ever-changing and dissimulative 4chan-current. It first argues how anti-structuralist research outlooks can answer to many of the pitfalls arising from this complex task. Afterwards, it traces the word trump as it was used on 4chan/pol/ to problematise some of the above-mentioned media narratives. How did anons consider Trump, and how did the /pol/-current change during the build-up of the 2016 U.S. elections and afterwards?On Researching Masked and Dissimulative ExtremistsWhile potentially playing into the self-imagination of malicious actors (Phillips et al.), the frequent appearance of overblown narratives on 4chan is unsurprising considering the peculiar affordances of imageboards. Imageboards are anonymous – no user account is required to post – and ephemeral – posts are deleted after a certain amount of activity, sometimes after days, sometimes after minutes (Bernstein et al.; Hagen). These affordances complicate studying collectives on imageboards, with the primary reasons being that 1) they prevent insights into user demographics, 2) they afford particularly dissimulative, playful discourse that can rarely be taken at face value (Auerbach; de Zeeuw and Tuters), and 3) the sheer volume of auto-deleted activity means one has to stay up-to-date with a rapid waterfall of subcultural ephemera. Additionally, the person stepping into the muddy waters of the chan-river also changes their gaze over time. For instance, Phillips bravely narrates how she once saw parts of the 4chan-stream as “fun” to only later realise the blatantly racist elements present from the start (“It Wasn’t Just”).To help render legible the changing currents of imageboard activity without relying on vague understandings of the “alt-right”, “trolls”, or “Anonymous”, anti-structuralist research outlooks form a possible answer. Around 1900, sociologists like Gabriel Tarde already argued to refrain from departing from structuralist notions of society and instead let social compositions arise through iterative tracing of minute imitations (11). As described in Bruno Latour’s Reassembling the Social, actor-network theory (ANT) revitalises the Tardean outlook by similarly criticising the notion of the “social” and “society” as distinct, sui-generis entities. Instead, ANT advocates tracing “flat” networks of agency made up of both human and non-human actors (165-72). By tracing actors and describing the emerging network of heterogeneous mediators and intermediaries (105), one can slowly but surely get a sense of collective life. ANT thus takes a page from ethnomethodology, which advocates a similar mapping of how participants of a group produce themselves as such (Garfinkel).For multiple reasons, anti-structuralist approaches like ANT can be useful in tracing elusive anonymous online groups and their changing compositions. First, instead of grasping collectives on imageboards from the outset through structuralist notions, as networked individuals, or as “amorphous and formless entities” (see e.g. Coleman 113-5), it only derives its composition after following where its actors lead. This can result in an empirical and literally objective mapping of their collectivity while refraining from mystifications and non-existent connections–so often present in popular narratives about “trolls” and the “alt-right”. At the same time, it allows prominent self-imaginations and mythologizations – or, in ANT-parlance, “localisations of the global” (Latour 173-190) – rise to the surface whenever they form important actors, which, as we will see, tends to happen on 4chan.Second, ANT offers a useful lens with which to consider how non-human actors can uphold a sense of collectivity within anonymous imageboards. This can include digital objects as part of the infrastructure–e.g. the automatically assigned post numbers having mythical value on 4chan (Beran, It Came From 69)–but also cultural objects like words or memes. Considering 4chan’s anonymity, this focus on objects instead of individuals is partly a necessity: one cannot know the exact amount and flow of users. Still, as this text seeks to show, non-human actors like words or memes can form suitable actors to map the changing collectivity of anonymous imageboard users in the absence of demographic insights.There are a few pitfalls worth noting when conducting ANT-informed research into extremist spaces like 4chan/pol/. The aforementioned ironic and dissimulative rhetoric of anonymous forum culture (de Zeeuw and Tuters) means tracing is complicated by implicit (yet omnipresent) intertextual references undecipherable to the untrained eye. Even worse, when misread or exaggerated, such tracing efforts can play into trolling tactics. This can in turn risk what Phillips calls “giving oxygen” to bigoted narratives by amplifying their presence (“Oxygen”). Since ANT does not prescribe what sort of description is needed (Latour 149), this exposure can be limited and/or critically engaged with by the researcher. Still, it is inevitable that research on extremist collectives adds at least some garbage to already polluted information ecologies (Phillips and Milner 2020), even when “just” letting the actors speak (Venturini). Indeed, this text will unfortunately also show hate speech terms below.These complications of irony and amplification can be somewhat mitigated by mixing ethnographic involvement with computational methods. Together, they can render implicit references explicit while also mapping broad patterns in imitation and preventing singular (misleading) actors from over-dominating the description. When done well, such descriptions do not only have to amplify but can also marginalise and trivialise. An accurate mapping can thereby counter sensationalist media narratives, as long as that is where the actors lead. It because of this potentiality that anti-structuralist tracing of extremist, dissimulative online groups should not be discarded outright.Stopping Momentarily to Test the WatersTo put the above into practice, what follows is a brief case study on the term trump on 4chan/pol/. Instead of following users, here the actor trump is taken an entry point for tracing various assemblages: not only referring to Donald J. Trump as an individual and his actions, but also to how /pol/-anons imagine themselves in relation to Trump. In this way, the actor trump is a fluid one: each of its iterations contains different boundaries and variants of its environment (de Laet and Mol 252). By following these environments, can we make sense of how the delirious 2016 U.S. election cycle played out on /pol/, a space described as the “skeleton key to the rise of Trump” (Beran, 4chan)?To trace trump, I use the 4plebs.com archive, containing almost all posts made on /pol/ between late-2013 and early 2018 (the time of research). I subsequently use two text mining methods to trace various connections between trump and other actors and use this to highlight specific posts. As Latour et al. note, computational methods allow “navigations” (593) of different data points to ensure diverse empirical perspectives, preventing both structuralist “zoomed-out” views and local contexts from over-dominating. Instead of moving between micro and macro views, such a navigation should therefore be understood as a “circulation” around the data, deploying various perspectives that each assemble the actors in a different way. In following this, the case study aims to demonstrate how, instead of a lengthy ethnographic account, a brief navigation using both quali- and quantitative perspectives can quickly demystify some aspects of seemingly nebulous online groups.Tracing trump: From Meme-Wizard to Anti-Semitic TargetTo get a sense of the centrality of Trump on /pol/, I start with post frequencies of trump assembled in two ways. The first (Figure 1) shows how, soon after the announcement of Trump’s presidential bid on 16 June 2015, around 100,000 comments mention the word (2% of the total amount of posts). The frequencies spike to a staggering 8% of all comments during the build-up to Trump’s win of the Republican nomination in early 2016 and presidential election in November 2016. Figure 1: The absolute and relative amount of posts on 4chan/pol/ containing the word trump (prefixes and suffixes allowed).To follow the traces between trump and the more general discourse surrounding it, I compiled a more general “trump-dense threads” dataset. These are threads containing thirty or more posts, with at least 15% of posts mentioning trump. As Figure 2 shows, at the two peaks, 8% of any thread on /pol/ was trump-dense, accounting for approximately 15,000 monthly threads. While Trump’s presence is unsurprising, these two views show just how incredibly central the former businessman was to /pol/ at the time of the 2016 U.S. election. Figure 2: The absolute and relative amount of threads on 4chan/pol/ that are “trump-dense”, meaning they have thirty comments or more, out of which at least 15% contain the word trump (prefixes and suffixes allowed).Instead of picking a certain moment from these aggregate overviews and moving to the “micro” (Latour et al.), I “circulate” further with Figure 3, showing another perspective on the trump­-dense thread dataset. It shows a scatter plot of trump-dense threads grouped per week and plotted according to how similar their vocabulary is. First, all the words per week are weighted with tf-idf, a common information retrieval algorithm that scores units on the basis if they appear a lot in one of the datasets but not in others (Spärck-Jones). The document sets are then plotted according to the similarity of their weighted vocabulary (cosine similarity). The five highest-scoring terms for the five clusters (identified with K-means) are listed in the bottom-right corner. For legibility, the scatterplot is compressed by the MDS algorithm. To get a better sense of specific vocabulary per week, terms that appeared in all weeks are filtered out (like trump or hillary). Read counterclockwise, the nodes roughly increase in time, thus showing a clear temporal change of discourse, with the first clusters being more similar in vocabulary than the last, and the weeks before and after the primary election (orange cluster) showing a clear gap. Figure 3: A scatterplot showing cosine distances between tf-idf weighted vocabularies of trump-dense threads per week. Compressed with MDS and coloured by five K-means clusters on the underlying tf-idf matrix (excluding terms that appeared in all weeks). Legend shows the top five tf-idf terms within these clusters. ★ denotes the median week in the cluster.With this map, we can trace other words appearing around trump as significant actors in the weekly documents. For instance, Trump-supportive words like stump (referring to “Can’t Stump the Trump”) and maga (“Make America Great Again”) are highly ranked in the first two clusters. In later weeks, less clearly pro-Trump terms appear: drumpf reminds of the unattractive root of the Trump family name, while impeached and mueller show the Russia probe in 2017 and 2018 were significant in the trump-dense threads of that time. This change might thus hint at growing scepticism towards Trump after his win, but it is not shown how these terms are used. Fortunately, the scatterplot offers a rudder with which to navigate to further perspectives.In keeping with Latour’s advice to keep “aggregate structures” and “local contexts” flat (165-72), I contrast the above scatterplot with a perspective on the data that keeps sentence structures intact instead of showing abstracted keyword sets. Figure 4 uses all posts mentioning trump in the median weeks of the first and last clusters in the scatterplot (indicated with ★) and visualises word trees (Wattenberg and Viégas) of most frequent words following “trump is a”. As such, they render explicit ontological associations about Trump; what is Trump, according to /pol/-anons? The first word tree shows posts from 2-8 November 2015, when fifteen Republican competitors were still in the race. As we have seen in Figure 1, Trump was in this month still “only” mentioned in around 50,000 posts (2% of the total). This word tree suggests his eventual nomination was at this point seen as an unlikely and even undesirable scenario, showing derogatory associations like retard and failure, as well as more conspiratorial words like shill, fraud, hillary plant, and hillary clinton puppet. Notably, the most prominent association, meme, and others like joke and fucking comic relief, imply Trump was not taken too seriously (see also Figure 5). Figure 4: Word trees of words following “trump is a” in the median weeks of the first and last clusters of the scatterplot. Made with Jason Davies’s Word Tree application. Figure 5: Anons who did not take Trump seriously. Screencapture taken from archive.4plebs.org (see post 1 and post 2 in context).The first word tree contrast dramatically with the one from the last median week from 18 to 24 December 2017. Here, most associations are anti-Semitic or otherwise related to Judaism, with trump most prominently related to the hate speech term kike. This prompts several questions: did /pol/ become increasingly anti-Semitic? Did already active users radicalise, or were more anti-Semites drawn to /pol/? Or was this nefarious current always there, with Trump merely drawing anti-Semitic attention after he won the election? Although the navigation did not depart from a particular critical framework, by “just following the actors” (Venturini), it already stumbled upon important questions related to popular narratives on 4chan and the alt-right. While it is tempting to stop here and explain the change as “radicalisation”, the navigation should continue to add more empirical perspectives. When doing so, the more plausible explanation is that the unlikely success of Trump briefly attracted (relatively) more diverse and playful visitors to /pol/, obscuring the presence and steady growth of overt extremists in the process.To unpack this, I first focus on the claim that a (relatively) diverse set of users flocked to /pol/ because of the Trump campaign. /pol/’s overall posting activity rose sharply during the 2016 election, which can point to already active users becoming more active, but is likely mostly caused by new users flocking to /pol/. Indeed, this can be traced in actor language. For instance, many anons professed to be “reporting in” from other 4chan boards during crucial moments in the campaing. One of the longest threads in the trump-dense threads dataset (4,504 posts) simply announces “Cruz drops out”. In the comments below, multiple anons state they arrived from other boards to join the Trump-infused activity. For instance, Figure 6 shows an anon replying “/v/ REPORTING IN”, to which sixty other users reacted by similarly affirming themselves as representatives from other boards (e.g. “/mu/ here. Ready to MAGA”). While but another particular view, this implies Trump’s surprising nomination stimulated a crowd-like gathering of different anons jumping into the vortex of trump-related activity on /pol/. Figure 6: Replies by outside-anons “reporting in” the sticky thread announcing Ted Cruz's drop out, 4 May 2016. Screenshots taken from 4plebs.org (see post 1 and post 2 in context).Other actor-language further expresses Trump’s campaign “drew in” new and unadjusted (or: less extreme) users. Notably, many anons claimed the 2016 election led to an “invasion of Reddit users”. Figure 7 shows one such expression: an annotated timeline of /pol/’s posting activity graph (made by 4plebs), posted to /pol/ on 26 February 2016 and subsequently reposted 34 times. It interprets 2016 as a period where “Trump shit goes into overdrive, meme shit floods /pol/, /pol/ is now reddit”. Whether these claims hold any truth is difficult to establish, but the image forms an interesting case of how the entirety “/pol/” is imagined and locally articulated. Such simplistic narratives relate to what Latour calls “panoramas”: totalising notions of some imagined “whole” (188-90) that, while not to be “confused with the collective”, form crucial data since they express how actors understand their own composition (190). Especially in the volatile conditions of anonymous and ephemeral imageboards, repeated panoramic narratives can help in constructing a sense of cohesion–and thereby also form interesting actors to trace. Indeed, following the panoramic statement “/pol/ is now reddit”, other gatekeeping-efforts are not hard to find. For instance, phrases urging other anons to go “back to reddit” (occurring in 19,069 posts in the total dataset) or “back to The_Donald” (a popular pro-Trump subreddit, 1,940 posts) are also particularly popular in the dataset. Figure 7: An image circulated on /pol/ lamenting that "/pol/ is now reddit" by annotating 4plebs’s posting metrics. Screenshot taken from archive.4plebs.org (see posts).Did trump-related activity on /pol/ indeed become more “meme-y” or “Reddit-like” during the election cycle, as the above panorama articulates? The activity in the trump-dense threads seems to suggest so. Figure 8 again uses the tf-idf terms from these threads, but here with the columns denoting the weeks and the rows the top scoring tf-idf terms of their respective week. To highlight relevant actors, all terms are greyed out (see the unedited sheet here), except for several keywords that indicate particularly playful or memetic vernacular: the aforementioned stump, emperor, referring to Trump’s nickname as “God Emperor”; energy, referring to “high energy”, a common catchphrase amongst Trump supporters; magic, referring to “meme magic”, the faux-ironic belief that posting memes affects real-life events; and pepe, the infamous cartoon frog. In both the tf-idf ranking and the absolute frequencies, these keywords flourish in 2016, but disappear soon after the presidential election passes. The later weeks in 2017 and 2018 rarely contain similarly playful and memetic terms, and if they do, suggest mocking discourse regarding Trump (e.g. drumpf). This perspective thus pictures the environment around trump in the run-up to the election as a particularly memetic yet short-lived carnival. At least from this perspective, “meme shit” thus indeed seemed to have “flooded /pol/”, but only for a short while. Figure 8: tf-idf matrix of trump-dense threads, columns denoting weeks and rows denoting the top hundred most relevant terms per week. Download the full tf-idf matrix with all terms here.Despite this carnivalesque activity, further perspectives suggest it did not go at the expense of extremist activity on /pol/. Figure 9 shows the absolute and relative counts of the word "jew" and its derogatory synonym "kike". Each of these increases from 2015 onwards. As such, it seems to align with claims that Trump’s success and /pol/ becoming increasingly extremist were causally related (Thompson). However, apart from possibly confusing correlation with causation, the relative presence remains fairly stable, even slightly decreasing during the frenzy of the Trump campaign. Since we also saw Trump himself become a target for anti-Semitic activity, these trendlines rather imply /pol/’s extremist current grew proportionally to the overall increase in activity, and increased alongside but not but necessarily as a partisan contingent as a result of Trump’s campaign. Figure 9: The absolute and relative frequency of the terms "jew" and "kike" on 4chan/pol/.ConclusionCombined, the above navigation implies two main changes in 4chan/pol/’s trump-related current. First, the climaxes of the 2016 Republican primaries and presidential elections seem to have invoked crowd-like influxes of (relatively) heterogeneous users joining the Trump-delirium, marked by particularly memetic activity. Second, /pol/ additionally seemed to have formed a welcoming hotbed for anti-Semites and other extremists, as the absolute amount of (anti-Semitic) hate speech increased. However, while already-present and new users might have been energised by Trump, they were not necessarily loyal to him, as professed by the fact that Trump himself eventually became a target. Together with the fact that anti-Semitic hate speech stayed relatively consistent, instead of being “countercultural” (Nagle) or exclusively pro-Trump, /pol/ thus seems to have been composed of quite a stable anti-Semitic and Trump-critical contingent, increasing proportionally to /pol/’s general growth.Methodologically, this text sought to demonstrate how a brief navigation of trump on 4chan/pol/ can provide provisional yet valuable insights regarding continuously changing current of online anonymous collectives. As the cliché goes, however, this brief exploration has left more many questions, or rather, it did not “deploy the content with all its connections” (Latour 147). For instance, I have not touched on how many of the trump-dense threads are distinctly separated and pro-Trump “general threads” (Jokubauskaitė and Peeters). Considering the vastness of such tasks, the necessity remains to find appropriate ways to “accurately map” the wild currents of the dissimulative Web–despite how muddy they might get.NoteThis text is a compressed and edited version of a longer MA thesis available here.ReferencesAbramson, Seth. “Listen Up, Progressives: Here’s How to Deal with a 4Chan (“Alt-Right”) Troll.” Medium, 2 May 2017. <https://medium.com/@Seth_Abramson/listen-up-progressives-heres-how-to-deal-with-a-4chan-alt-right-troll-48594f59a303>.Auerbach, David. “Anonymity as Culture: Treatise.” Triple Canopy, n.d. 22 June 2020 <https://www.canopycanopycanopy.com/contents/anonymity_as_culture__treatise>.Beran, Dale. “4chan: The Skeleton Key to the Rise of Trump”. Medium, 14 Feb. 2017. <https://medium.com/@DaleBeran/4chan-the-skeleton-key-to-the-rise-of-trump-624e7cb798cb>.Beran, Dale. It Came from Something Awful: How a Toxic Troll Army Accidentally Memed Donald Trump into Office. New York: All Points Books, 2019.Bernstein, Michael S, Andrés Monroy-Hernández, Drew Harry, Paul André, Katrina Panovich, and Greg Vargas. “4chan and /b/: An Analysis of Anonymity and Ephemerality in a Large Online Community.” Proceedings of the Fifth International AAAI Conference on Weblogs and Social Media, 2011.Coleman, Gabriella. Hacker, Hoaxer, Whistleblower, Spy: The Many Faces of Anonymous. London: Verso Books, 2014.De Laet, Marianne, and Annemarie Mol. “The Zimbabwe Bush Pump: Mechanics of a Fluid Technology.” Social Studies of Science 30.2 (2000): 225–263. 1 May 2020 <https://journals.sagepub.com/doi/10.1177/030631200030002002>. De Zeeuw, Daniel, and Marc Tuters. “Teh Internet Is Serious Business: On the Deep Vernacular Web Imaginary.” Cultural Politics 16.2 (2020).Dewey, Caitlin. “The Only True Winners of this Election are Trolls.” The Washington Post, 3 Nov. 2016. <https://www.washingtonpost.com/news/the-intersect/wp/2016/11/03/the-only-true-winners-of-this-election-are-trolls/>.Faris, Robert, Hal Roberts, Bruce Etling, Nikki Bourassa, Ethan Zuckerman, and Yochai Benkler. “Partisanship, Propaganda, and Disinformation: Online Media and the 2016 U.S. Presidential Election.” Berkman Klein Center Research Publication, 2017. <http://nrs.harvard.edu/urn-3:HUL.InstRepos:33759251>.Garfinkel, Harold. Studies in Ethnomethodology. New Jersey: Prentice-Hall, 1967.Hagen, Sal. “Rendering Legible the Ephemerality of 4chan/pol/.” OILab.eu, 12 Apr. 2020. <https://oilab.eu/rendering-legible-the-ephemerality-of-4chanpol/>.Hawley, George. Making Sense of the Alt-Right. New York: Columbia UP, 2017.Jokubauskaitė, Emilija, and Stijn Peeters. “Generally Curious: Thematically Distinct Datasets of General Threads on 4chan/Pol/”. Proceedings of the International AAAI Conference on Web and Social Media 14.1 (2020): 863-7. <https://www.aaai.org/ojs/index.php/ICWSM/article/view/7351>.Latour, Bruno. Reassembling the Social: An Introduction to Actor-Network Theory. New York: Oxford UP, 2005.Latour, Bruno, Pablo Jensen, Tommaso Venturini, Sébastian Grauwin, and Dominique Boullier. “‘The Whole Is Always Smaller than Its Parts’. A Digital Test of Gabriel Tarde’s Monads.” British Journal of Sociology 63.4 (2012): 590-615.Marantz, Andrew. Antisocial: Online Extremists, Techno-Utopians, and the Hijacking of the American Conversation. New York: Penguin Random House, 2019.Nagle, Angela. Kill All Normies: Online Culture Wars from 4chan and Tumblr to Trump and the White House. Winchester: Zero Books, 2017.Phillips, Whitney. This Is Why We Can’t Have Nice Things: Mapping the Relationship between Online Trolling and Mainstream Culture. Cambridge: MIT Press, 2015.———. “The Alt-Right Was Conjured Out of Pearl Clutching and Media Attention.” Motherboard, 12 Oct. 2016 <https://www.vice.com/en_us/article/jpgaeb/conjuring-the-alt-right>.———. “The Oxygen of Amplification: Better Practices for Reporting on Extremists, Antagonists, and Manipulators Online.” Data & Society, 2018. <https://datasociety.net/wp-content/uploads/2018/05/1_PART_1_Oxygen_of_Amplification_DS.pdf>.———. “It Wasn’t Just the Trolls: Early Internet Culture, ‘Fun,’ and the Fires of Exclusionary Laughter.” Social Media + Society (2019). <https://journals.sagepub.com/doi/10.1177/2056305119849493>.Phillips, Whitney, Gabriella Coleman, and Jessica Beyer. “Trolling Scholars Debunk the Idea That the Alt-Right’s Shitposters Have Magic Powers.” Motherboard, 22 Mar. 2017. <https://motherboard.vice.com/en_us/article/z4k549/trolling-scholars-debunk-the-idea-that-the-alt-rights-trolls-have-magic-powers>.Robertson, Adi. “Hillary Clinton Exposing Pepe the Frog Is the Death of Explainers.” The Verge, 15 Sep. 2016. <https://www.theverge.com/2016/9/15/12926976/hillary-clinton-trump-pepe-the-frog-alt-right-explainer>.Spärck Jones, Karen. “A Statistical Interpretation of Term Specificity and its Application in Retrieval.” Journal of Documentation 28.1 (1972): 11-21.Stuart, Tessa. “Inside the DeploraBall: The Trump-Loving Trolls Plotting a GOP Takeover.” Rolling Stone, 20 Jan. 2017. <https://www.rollingstone.com/politics/politics-features/inside-the-deploraball-the-trump-loving-trolls-plotting-a-gop-takeover-128128/>.Tarde, Gabriel. The Laws of Imitation. Ed. and trans. Elsie Clews Parsons. New York: Henry Holt and Company, 1903.Thompson, Andrew. “The Measure of Hate on 4chan.” Rolling Stone, 10 May 2018. <https://www.rollingstone.com/politics/politics-news/the-measure-of-hate-on-4chan-627922/>.Venturini, Tommaso. “Diving in Magma: How to Explore Controversies with Actor-Network Theory.” Public Understanding of Science 19.3 (2010): 258-273.Wattenberg, Martin, and Fernanda Viégas. “The Word Tree, an Interactive Visual Concordance.” IEEE Transactions on Visualization and Computer Graphics 14.6 (2008): 1221-1228.

This work seeks to illustrate the potential benefits afforded by implementing aspects of fluid dynamics, especially the latest computational fluid dynamics (CFD) modeling approach, through numerical experimentation and the traditional discipline of physical experimentation to improve the calibration of the severe reactor accident analysis code, MELCOR, in one of several spent fuel pool (SFP) complete loss-of-coolant accident (LOCA) scenarios. While the scope of experimental work performed by Sandia National Laboratories (SNL) extends well beyond that which is reasonably addressed by our allotted resources and computational time in accordance with initial project allocations to complete the report, these simulated case trials produced a significant array of supplementary high-fidelity solutions and hydraulic flow-field data in support of SNL research objectives. Results contained herein show FLUENT CFD model representations of a 9x9 BWR fuel assembly in conditions corresponding to a complete loss-of-coolant accident scenario. In addition to the CFD model developments, a MATLAB based control-volume model was constructed to independently assess the 9x9 BWR fuel assembly under similar accident scenarios. The data produced from this work show that FLUENT CFD models are capable of resolving complex flow fields within a BWR fuel assembly in the realm of buoyancy-induced mass flow rates and that characteristic hydraulic parameters from such CFD simulations (or physical experiments) are reasonably employed in corresponding constitutive correlations for developing simplified numerical models of comparable solution accuracy.
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Spent nuclear fuel (SNF) integrity evaluation related to its handling and transportation for mid-/long-term dry storage is a regulatory requirement. Especially, a drop event is the most fatal failure mode among regulatory conditions. For SNF drop accidents, it is required that the mechanical integrity of the SNF be evaluated using test results or analytic methodologies. The SNF mechanical test, however, takes much time and cost, and there are safety issues related to the release of radioactive materials. Thus, finite element analysis is used as an alternative to the experimental test method to solve this problem. In this study, a three dimensional (3D) finite element model was developed using ABAQUS software to simulate the structural behaviors of a fresh fuel assembly (FA) prior to applying SNF properties because of a lack of SNF test results. Static and dynamic mechanical behaviors were simulated with this model and compared with the fresh FA test results. The analysis results are in good agreement with the test results. Therefore, the analysis model consistent with the test results will be applied to the evaluation of the FA drop integrity reflecting the specific SNF characteristics.

In this paper we have analyzed accounting spent nuclear fuel (SNF) burnup of VVER-1000 and RBMK-1000 only with actinides. The following characteristics were analyzed: initial fuel enrichment, burnup fraction, axial burnup profile in the fuel assembly (FA) and fuel weight. As the results show, in the first 400 hours after stopping the reactor, there is an increase in the effective neutron multiplication factor (keff) due to beta decay of 239Np into 239Pu. Further, from 5 to 50 years, decrease in keff due to beta decay of 241Pu into 241Am. In the future there is a slight change in criticality of the system. Accounting nuclear fuel burnup in the justification of nuclear safety of SNF storages will provide an opportunity to increase the volume of loaded fuel and thus significantly reduce technology costs of handling of SNF.

In this paper accounting of spent nuclear fuel (SNF) burnup of RBMK-1000 with actinides and full isotopic composition has been performed. The following characteristics were analyzed: initial fuel enrichment, burnup fraction, axial burnup profile in the fuel assembly (FA) and fuel weight. As the results show, in the first 400 hours after stopping the reactor, there is an increase in the effective neutron multiplication factor (keff) due to beta decay of 239Np into 239Pu. Further, from 5 to 50 years, there is a decrease in keff due to beta decay of 241Pu into 241Am. Beyond 50 years there is a slight change in the criticality of the system. Accounting for nuclear fuel burnup in the justification of nuclear safety of SNF systems will provide an opportunity to increase the volume of loaded fuel and thus significantly reduce technology costs of handling of SNF.

PWR fuel assembly (FA) experiences many changes from the time it is manufactured, loaded in the reactor and removed from the reactor for reprocessing or stroage etc. Any of these alterations which impact spent nuclear fuel (SNF) integrity should be considered to design a cask/canister. Regarding the cask/canister design, there could be a freedom to design a system that mitigates the forces transmitted to SNF and fuel rods. If the cask/canister design prevents or mitigates forces transmitted to its contents such that structural integrity is not significantly compromised, the detailed SNF properties are necessary to make a decision of the elaborated design parameters. An approach to those work formations is to analyze mechanical characteristics of structural components. Those informations are also used to evaluate hypothetical accident, to select limiting FA for cask/canister to accommodate various kinds of SNFs and to design transportation/storage system for SNFs. Especially, FA structural properties are a sort of essential data. Thus, in this paper, some approaches to evaluate SNF mechanical characteristics are suggested through the existing technical information review, some test data and the analysis methodology, and also closely study the mechanical characteristics of a representative SNF for its general comprehension.

In this paper accounting of spent nuclear fuel (SNF) burnup of RBMK-1000 only with actinides has been performed. The following characteristics were analyzed: initial fuel enrichment, burnup fraction, axial burnup profile in the fuel assembly (FA) and fuel weight. As the results show, in the first 400 hours after stopping the reactor, there is an increase in the effective neutron multiplication factor (keff) due to beta decay of 239Np into 239Pu. Further, from 5 to 50 years, there is a decrease in keff due to beta decay of 241Pu into 241Am. Beyond 50 years there is a slight change in the criticality of the system. Accounting for nuclear fuel burnup in the justification of nuclear safety of SNF systems will provide an opportunity to increase the volume of loaded fuel and thus significantly reduce technology costs of handling of SNF.

Within the EURATOM FP7 Collaborative Project “Fast / Instant Release of Safety Relevant Radionuclides from Spent Nuclear Fuel (CP FIRST-Nuclides)”, a State-of-the-Art Report was prepared. The fast / instant release fraction (IRF) is defined as a fraction of the inventory of radionuclides that may be rapidly released from the fuel and fuel assembly materials at the time of canister breaching. In the context of safety analysis for a repository, the time span for mobilization of this fraction can be considered instantaneously, even if the process takes some time in experiments. Radionuclides contributing to the fast release are fission gases (Kr and Xe), easily soluble elements such as cesium and iodine, and other elements which are hardly incorporated in the UO2 crystal lattice. The present contribution summarizes the results obtained from published studies focused on rapid release experiments carried out with different spent nuclear fuel (SNF), samples, sizes, techniques (batch and flow-through), and durations. A total of 80 experiments cover the study of UO2 SNF from pressure water reactors (PWR) of different initial enrichments and burn-up, while 20 experiments were performed with UO2 SNF from boiling water reactors (BWR) and 8 with MOX fuel.

The National Spent Nuclear Fuel Program (NSNFP) at the Idaho National Engineering and Environmental Laboratory (INEEL) prepared four representative Department of Energy (DOE) spent nuclear fuel (SNF) canisters for the purpose of drop testing. The first two canisters represented a modified 24-inch diameter standardized DOE SNF canister and the second two canisters represented the Hanford Multi-Canister Overpack (MCO). The modified canisters and internals were constructed and assembled at the INEEL. The MCO internal weights were fabricated at the INEEL and assembled into two MCOs at Hanford and later shipped to the INEEL for drop test preparation. Drop testing of these four canisters was completed in August 2004 at Sandia National Laboratories. The modified canisters were dropped from 30 feet onto a flat, essentially unyielding surface, with the canisters oriented at 45 degrees and 70 degrees off-vertical at impact. One representative MCO was dropped from 23 feet onto the same flat surface, oriented vertically at impact. The second representative MCO was dropped onto the flat surface from 2 feet oriented at 60 degrees off-vertical. These drop heights and orientations were chosen to meet or exceed the Yucca Mountain repository drop criteria. This paper discusses the comparison of deformations between the actual dropped canisters and those predicted by pre-drop and limited post-drop finite element evaluations performed using ABAQUS/Explicit. Post-drop containment of all four canisters, demonstrated by way of helium leak testing, is also discussed.

INPRO has defined requirements organized in a hierarchy of Basic Principles, User Requirements and Criteria (consisting of an indicator and an acceptance limit) to be met by innovative nuclear reactor systems (INS) in six areas, namely: economics, safety, waste management, environment, proliferation resistance, and infrastructure. If an INS meets all requirements in all areas it represents a sustainable system for the supply of energy, capable of making a significant contribution to meeting the energy needs of the 21st century. Draft manuals have been developed, for each INPRO area, to provide guidance for performing an assessment of whether an INS meets the INPRO requirements in a given area. The manuals set out the information that needs to be assembled to perform an assessment and provide guidance on selecting the acceptance limits and, for a given INS, for determining the value of the indicators for comparison with the associated acceptance limits. Each manual also includes an example of a specific assessment to illustrate the guidance. This paper discusses the manual for performing an INPRO assessment in the area of safety of fuel cycle installations. The example, chosen solely for the purpose of illustrating the INPRO methodology, describes an assessment of an MOX fuel fabrication plant based on sol-gel technology and illustrates an assessment performed for an INS at an early stage of development. The safety issues and the assessment steps are presented in detail in the paper.

The research here presented is focused on the laser based experimental characterisation of an Ansaldo Energia burner equipping the Heavy Duty gas turbine (HD). The component is a partially premixed, swirl stabilized burner, adopting a central axial swirler surrounded by a mixed-flow, radially inward one. The burner can be fed with gaseous and liquid fuels by adopting three different injection modalities: diffusion, premixed and pilot injections. The experimental campaigns were carried out at DIMSET/SCL, the Savona Combustion Laboratory, within a joint research initiative between Ansaldo Energia and DIMSET (University of Genoa), on a full scale burner-combustor assembly, by scaling the base load operational conditions to ambient pressure under a Mach number similitude. The research activities performed have been addressed at achieving a detailed set of experimental data adequate to obtain a complete unsteady flow field characterisation in terms of velocity components’ radial distributions together with their local turbulent and periodical fluctuations within the combustor primary zone. In this way, the inner recirculation region at the burner exit can be neatly identified. Furthermore, the main fluid-dynamical parameters of the turbulent flow have been calculated, in terms of turbulent kinetic energy, turbulence intensity, Reynolds stresses and swirl number in order to characterise in detail the burner-combustor assembly from a fluid-dynamics point of view. The said investigations being performed with different operational and geometrical settings and properly managed in order to allow further burner developments at the technological/industrial level. In parallel, the research activities have also pursued the target of performing a thorough velocity fluctuation analysis, to be correlated with possible combustion instabilities, in order to attain a deeper comprehension of phenomena typically affecting gas turbine combustors, such as thermo-acoustical instabilities (humming). The velocity fluctuations have been investigated with particular reference to their inception locations within the burner: it turned out that they are typically related to the presence of the two different swirlers, which induce peculiar interactions between two different flow structures, each one presenting its own dynamical characteristics.