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The effect of clearance upon friction and lubrication of large diameter hip resurfacing prosthesis using blood and combinations of bovine serum with aqueous solutions of CMC and hyaluronic acid as lubricants.Afshinjavid, Saeed January 2010 (has links)
In real life, immediately after joint replacement, the artificial joint is actually bathed in blood
(and clotted blood) instead of synovial fluid. Blood contains large molecules and cells of size
~ 5 to 20 2m suspended in plasma and considered to be a non-Newtonian (pseudoplastic)
fluid with density of 1060 Kg/m3 and viscosity ~ 0.01 Pas at shear rates of 3000 s-1 (as
obtained in this work). The effect of these properties on friction and lubrication is not fully
understood and, so far to our knowledge, hardly any studies have been carried out regarding
friction of metal-on-metal bearings with various clearances in the presence of lubricants such
as blood or a fluid containing macromolecules such as hyaluronic acid (HA) which is a major
component of synovial fluid increasing its viscosity and lubricating properties. In this work,
therefore, we have investigated the frictional behaviour of a group of Smith and Nephew
Birmingham Hip Resurfacing implants with a nominal diameter of 50mm and diametral
clearances in the range ~ 80 2m to 300 2m, in the presence of blood (clotted and whole
blood), a combination of bovine serum (BS) with hyaluronic acid (HA) and carboxymethyl
cellulose (CMC, as gelling agent) adjusted to a range of viscosities (~0.001-0.2 Pas), and
bovine serum with CMC adjusted to a similar range of viscosities.
These results suggested that reduced clearance bearings have the potential to generate high
friction especially in the presence of blood which is indeed the in vivo lubricant in the early
weeks after implantation. Friction factors in higher clearance bearings were found to be lower
than those of the lower clearance bearings using blood as the lubricant. Similar trends, i.e.
increase in friction factor with reduction in diametral clearance, were found to be also the
case using a combination of BS+CMC or BS+HA+CMC as lubricants having viscosities in
the range 0.1-0.2 and 0.03-0.14 Pas, respectively. On the other hand, all the lubricants with
lower viscosities in the range 0.001-0.0013 and 0.001-0.013 Pas for both BS+CMC and BS+HA+CMC, respectively, showed the opposite effect, i.e. caused an increase in friction
factor with increase in diametral clearance.
Another six large diameter (50mm nominal) BHR deflected prostheses with various
clearances (~ 50-2802m after cup deflection) were friction tested in vitro in the presence of
blood and clotted blood to study the effect of cup deflection on friction. It was found that the
biological lubricants caused higher friction factors at the lower diametral clearances for blood
and clotted blood as clearance decreased from 2802m to 502m (after deflection).
The result of this investigation has suggested strongly that the optimum clearance for the 50
mm diameter MOM BHR implants to be ¿1502m and <2352m when blood lubricant used, so
as to avoid high frictions (i.e. avoid friction factors >0.2) and be able to accommodate a
mixed lubrication mode and hence lower the risk of micro- or even macro-motion specially
immediately after hip implantation. These suggested optimum clearances will also allow for
low friction (i.e. friction factors of <0.2-0.07) and reasonable lubrication (dominantly mixed
regime) for the likely cup deflection occurring as a result of press-fit fixation. / Smith & Nephew Orthopaedics Ltd.
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Polymers at the Electrode-Electrolyte Interface : Negative Electrode Binders for Lithium-Ion BatteriesJeschull, Fabian January 2017 (has links)
We are today experiencing an increasing demand for high energy density storage devices like the lithium-ion battery for applications in portable electronic devices, electric vehicles (EV) and as interim storage for renewable energy. High capacity retention and long cycle life are prerequisites, particularly for the EV market. The key for a long cycle life is the formation of a stable solid-electrolyte interphase (SEI) layer on the surface of the negative electrode, which typically forms on the first cycles due to decomposition reactions at the electrode-electrolyte interface. More control over the surface layer can be gained when the layer is generated prior to the battery operation. Such a layer can be tailored more easily and can reduce the loss of lithium inventory considerably. In this context, water-soluble electrode binders, e.g. sodium carboxymethyl cellulose (CMC-Na) and poly(acrylic acid) (PAA), have proven themselves exceptionally useful. Since the binder is a standard component in composite electrodes anyway, its integration into the electrode fabrication process is easily accomplished. This thesis work investigates the parameters that govern binder distribution in elec-trode coatings, control the stability and electrochemical performance of the elec-trode and that determine the composition of the surface layer. Several commonly used electrode materials (graphite, silicon and lithium titanate) have been applied in order to study the impact of the binder on the electrode morphology and the differ-ent electrode-electrolyte interfaces. The results are correlated with the electrochemi-cal performance and with the SEI composition obtained by in-house and synchro-tron-based photoelectron spectroscopy (PES). The results demonstrate that the poor swellability of these water-soluble binders leads to a protection of the active material, given that the surface coverage is high and the binder evenly distributed. Although on the laboratory scale electrode formu-lations with a high binder content are common, they have little practical use in commercial devices due to the high content of inactive material. As the binder con-tent is decreased, complete surface coverage is more difficult to achieve and the binder distribution is more strongly coupled to the particle-binder interactions during the preparation process. Moreover, it is demonstrated in this thesis how these inter-actions are related to the surface area of the electrode components applied, the surface composition and the electrochemistry of the electrode. As a result of the smaller binder contents the benefits provided by CMC-Na and PAA at the electrode surface are compromised and the performance differs less distinctly from electrodes fabricated with the conventional binder, i.e. poly(vinylidene difluoride) (PVdF). Composites of alloying and conversion materials, on the other hand, typically em-ploy binders in larger amounts. Despite the frequently noted resiliency to volume expansion, which is also a positive side effect of the poor swellability of the binder in the electrolyte, the protection of the surface and the formation of a more stable interface are the major cause for the improved electrochemical behaviour, com-pared to electrodes employing PVdF binders.
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Angličtina na Facebooku: ke specifickým rysům angličtiny v internetové komunikaci / Facebook English: on the specific features of English netspeakMišutková, Anna January 2014 (has links)
The aim of this thesis is to describe the language of electronic communication ('netspeak') as one of the present trends of the development of English. The thesis is based on the hypothesis 'netspeak' represents an independent multimodal linguistic variety sharing some features with informal face-to-face conversation. For this purpose, the language of selected samples of the texts of English-speaking students of British universities obtained from the social network Facebook was studied. The qualitative and quantitative analysis of these data and their comparison with spoken form of standard English, namely with the spoken demographically sampled part of the British National Corpus, confirmed the hypothesis. ! Key words: netspeak, CMC, Facebook, emoticons, face-to-face communication, informal conversation
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Hedging Rule Discussions : A study on hedging and emoticons in an online board game discussion forumAldén, Joakim January 2019 (has links)
In everyday language, people tend to speak in a non-committing fashion when making claims, either to save their own face or to save another person’s face. In linguistics, this is called hedging, with common words and expressions such as probably, assume and I don’t know often revealing that a hedging speech act has been performed. In computer-mediated communication, Skovholt et al. (2014) discovered that emoticons, rather than signaling the sender’s emotions, were used to hedge. This study aims to further investigate the matter by looking at how users on a board game forum hedge when speaking about board games’ complexity with the research question “do more complex games involve more hedge usage on the board game forum Boardgamegeek?” as the point of departure. Data was taken from forum posts tagged with rules. The results showed that complexity barely increases the likelihood of hedging, with a slight edge given to simpler games.
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Biotype composition and virulence distribution of wheat curl mite in the North Central United StatesKhalaf, Luaay Kahtan January 1900 (has links)
Doctor of Philosophy / Department of Entomology / C. Michael Smith / The wheat curl mite, Aceria tosichella (Keifer), is an important global pest of bread wheat, Triticum aestivum L. Chronic and often severe reductions of winter wheat yield due to A. tosichella infestations have occurred in North America and all other wheat-production areas for over five decades. Moreover, A. tosichella is the only vector which transmits the three most important wheat viruses in the Great Plains, which are Wheat Streak Mosaic Virus (WSMV), the most economically important wheat virus in North America; Triticum Mosaic Virus (TriMV) and High Plains Wheat Mosaic Virus (HPWMoV). Mite infestation alone causes stunted, chlorotic plants in susceptible wheat varieties. To date, mite resistant wheat cultivars have been the only sufficient method to control A. tosichella. The discovery of new genes for A. tosichella resistance and their introgression into wheat cultivars are essential steps to combat the development of new and/or different A. tosichella biotypes which can develop to overcome resistance genes. Both A. tosichella biotype 1 and 2 exist in U. S. Great Plains wheat producing areas. Elucidating and predicting A. tosichella population composition changes based on climatic and geographic variables is a key to continued effective mite management. Experiments were conducted to: 1) assess A. tosichella virulence in mites collected from 25 sample sites in six states to wheat plants harboring the Cmc2, Cmc3 and Cmc4 mite resistance genes and the Wsm2 WSMV resistance gene in 2014 and 2015, and determine the distribution of WSMV, TriMV and HPWMoV present in mites collected; 2) assess A. tosichella biotype composition using internal transcribed spacer 1 (ITS1) and cytochrome oxidase I (COI) polymorphisms; 3) use generalized additive modeling to capture the spatio-temporal factors contributing to the prevalence of A. tosichella biotypes 1 and 2; and 4) screen Kansas advanced breeding lines for resistance to A. tosichella biotypes 1 and 2.
Results indicated that A. tosichella collected from 92% of the sample area were virulent to susceptible Jagger wheat plants with no Cmc resistance genes; that mites from 36% of the sample area were virulent to the Cmc2 gene, and that mites collected from 24% of sample area were virulent to Cmc3. Mite populations from only 8% of the sample sites exhibited virulence to plants containing Cmc4 + Wsm2 or Cmc4. The WSMV virus was predominant and present in 76% of all mites sampled. HPWMoV and TriMV were less apparent and present in 16% and 8% of all mites sampled, respectively. These results will enable breeders to increase the efficiency of wheat production by releasing wheat varieties containing A. tosichella resistance genes that contribute to reducing virus transmission. Results of spatio-temporal factor modeling provide new, more accurate information about the use of ground-cover and precipitation as key predictors of biotype prevalence and ratio.
Experiments to determine if Kansas State University advanced breeding lines contain A. tosichella resistance found no resistance to biotype 1, resistance to biotype 2 in breeding lines AYN3-37 and AYN3-34; and moderate resistance to biotype 2 in breeding lines AYN2-28 and AYN2-36.
The demonstrated correlation between reduced A. tosichella population size and avirulence; characterization and prediction of the A. tosichella biotype composition; and the identification of new sources of A. tosichella resistance in wheat can help entomologists and wheat breeders increase wheat production efficiency by releasing additional wheat cultivars containing A. tosichella resistance genes.
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Pragmatic Quotation Use in Online Yelp Reviews and its Connection to Author SentimentWright, Mary Elisabeth 01 March 2016 (has links)
Previous research has established that punctuation can be used to communicate nuances of meaning in online writing (McAndrew & De Jonge, 2011). Punctuation, considered a computer mediated communication (CMC) cue, expresses tone and emotion and disambiguates an author's intention (Vandergriff, 2013). Quotation marks as CMC cues can serve pragmatic functions and have been understudied. Some of these functions have been generally described (Predelli, 2003). However, no corpus study has specifically focused on the pragmatic uses of quotations in online text. Consumer reviews, a genre of online text, can directly impact business profits and influence customers' purchasing decisions (Floyd, Freling, Alhoqail, Cho & Freling, 2014). Businesses are investing in sentiment analysis to gauge their target market's opinions (Salehan & Kim, 2016). Sentiment analysis is the computerized appraisal of a text to determine whether its author is expressing a positive or negative opinion (Novak, Smailovic, Sluban & Mozetic, 2015). Sentiment analysis programs are still limited and could be improved in accuracy. Most programs rely on lexicons of words given a pre-determined polarity value (positive or negative) out of context (Novak et al., 2015). However, context is crucial to communication, and sentiment analysis programs could incorporate a better variety of contextual linguistic features to improve their accuracy. Quotations used for pragmatic communication is such a feature. This study discovered seven pragmatic quotation uses in a 2014 Yelp review corpus: Collective Knowledge, Non-standard, Grammatical, Non-literal, Narrative, Idiolect, and Emphasis. An ANOVA and Tukey HSD test were performed, and the results were significant. Pragmatic category accounted for 15% of the variance in review star rating. The Collective Knowledge category and the Narrative and Non-literal categories were significantly different from each other. The Collective Knowledge category showed a correlation with positive sentiment, while the Narrative and Non-literal categories displayed a correlation with negative sentiment. These three categories are likely present in several types of online text, making them valuable for further sentiment analysis research. If these pragmatic patterns could be detected automatically, they could be used in sentiment algorithms to give a more accurate picture of author opinion.
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The dilemmatic nature of luring communication: an action-implicative discourse analysis of online predator and P-J member interactionBuchanan, Lauren-Ashley 01 May 2016 (has links)
The occurrence of child sex abuse in the United States has long been considered a problem of paramount importance (e.g. Durkin, 2002; Howitt, 2008; Jenkins, 1998). Historically, the primary assumption was that the sexual solicitation of children occurred face-to-face. However, with the advent of communication technologies, people began to realize the internet's role in child solicitation. In an effort to combat this mode of child luring, a concerned citizen created P-J, an organization that seeks to identify and incriminate online predators (OPs). Members of this organization (PJMs) wait in online spaces for OPs to approach them. Then PJMs communicate as if they are minors to gather incriminating evidence against the OPs. PJMs and OPs have incompatible goals for their interactions. OPs' aim to foster a sexual relationship with a minor without being punished for it. PJMs' aim to gather enough evidence against OPs to convict them and prevent the future luring of children. To accomplish these goals, PJMs and OPs communicate with each other and face unique dilemmas in doing so.
The current dissertation employs Action-Implicative Discourse Analysis (AIDA; Tracy, 1995), a theory-method package that helps identify strategies used by interactants to address their institutionally based communicative dilemmas, to answer the research questions: 1) How do PJMs communicatively address their dilemma of encouraging online predators to pursue sexual contact without entrapping or making OPs suspicious, and 2) How do OPs communicatively address their dilemma of seducing their targets without getting caught or scaring off the presumed minor? By doing so, the project expands extant knowledge of grooming and computer-mediated self-presentation. It also extends the use of AIDA to contexts beyond organizations and formal institutions.
Through the sampling and constant comparison procedure of 40 PJM-OP instant messenger transcripts provided by the organization's website, the researcher identified four overarching categories of strategies that PJMs used to manage their dilemma: Target Presentation, OP Safety, Sexual/Relational Contribution Management, and Bust Facilitation. The researcher also identified five overarching categories of strategies for OPs: Identity Establishment, Relationship Management, Safety Precautions, Sexual Communication Engagement, and Meet Facilitation. Within these categories are many strategies PJMs and OPs utilized in an effort to address their dilemmas of attaining their goals while avoiding risks.
By identifying the aforementioned strategies, the researcher satisfied her primary goal of recognizing and understanding how PJMs and OPs attempt to reach their respective goals while avoiding risks. In addition to fulfilling this primary goal, the results of this project entail implications for several different lines of research. Specifically, the results of this dissertation extend research on traditional and online grooming, self-presentation online, and AIDA. The results also provide practical implications concerning what adolescents should be wary of when communicating with unknown others online. Additionally, the study has the capacity to help PJMs become more aware of OPs' strategies as well as their own. This awareness could help PJMs more efficiently train new PJMs and gain a deeper understanding of their interactions.
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Ungdomars identitetsskapande och livsvillkor : Fyra studier om ungdomar i fyra olika kontexterDahlgren, Erika, Jarlengrip, Karl, Jonsson, Gong, Kronblad, Christopher January 2006 (has links)
<p>Ungdomars identitetsskapande och livsvillkor är vad vår antologi handlar om. Det vi har studerat är hur ungdomar väljer att leva i det nutida samhället. I och med de stora valmöjligheterna och människors reflexiva förmåga uppkommer ständigt rädslan att de val vi gör kanske är fel. Ungdomstiden vi tar upp i denna antologi kan ses som något specifikt avgörande för skapandet av den personliga identiteten. De teman vi kommer att behandla är unga kristna i dagens samhälle och deras tro i koppling till deras identitetsskapande, punkens betydelse för ungdomars identitet och hur samhället ser på dem, hur användandet av tekniken har påverkat unga människor med dess fördelar och nackdelar. Till sist tar vi upp unga tjejers syn på förhållanden, kärlek och sex. Vi har genom intervjuer med ungdomar i åldrarna 16-26 studerat deras syn på identitet och livsvillkor ur olika perspektiv och sammanhang.</p>
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Gultekin, Burhan 01 September 2012 (has links) (PDF)
This research and development work deals with the design methodology for
Cascaded Multilevel Converter (CMC) based Transmission STATCOM (TSTATCOM)
and development of a ± / 12MVAR, 12kV line-to-line wye-connected,
11-level CMC. This CMC module constitutes the basic building block of TSTATCOM
systems. Sizing of the CMC module, number of H-Bridges in each phase
of the CMC, AC voltage rating of the CMC, the number of paralleled CMC modules
in the T-STATCOM system, optimum value of series filter reactors and
determination of busbar in the power grid to which the T-STATCOM system is
going to be connected are also discussed in the thesis in view of IEEE Std.519-1992,
current status of HV IGBT technology and the required reactive power variation
range for the T-STATCOM application. In the field prototype of the CMC module,
the AC voltages are approximated to sinusoidal waves by Selective Harmonic
Elimination Method (SHEM) and by the use of an optimized series input filter
reactor. The use of n number of HBs in each phase provides us n number of freedom in the application of SHEM. One of them is allocated to the fundamental component
while n-1 is for the elimination of low order harmonics. Since n is chosen to five in
the prototype system, 5th, 7th,11th and 13th harmonic components are successfully
eliminated in the AC voltage waveforms of the CMC module. The equalization of
DC link capacitor voltages is achieved according to Modified Selective Swapping
(MSS) algorithm. MSS is applied every 400&mu / s period if needed to obtain a perfect
equalization of DC link capacitor voltages at the expense of higher switching
frequency and hence switching losses. In this research work, an L-shaped laminated
bus has been designed and the HV IGBT driver circuit has been modified for
optimum switching performance of HV IGBT modules in each HB circuit. The
performances of the HB circuit and the resulting 11-level CMC module have been
obtained not only in the laboratory but also in the field. Design works for HB and the
CMC are based on MATLAB and PSCAD simulations. The laboratory and field
performance of the HB circuit and CMC module is found to be satisfactory and quite
consistent with the theoretical results and design objectives. In addition to these, 154
kV, ± / 50MVAr T-STATCOM prototype has been designed, implemented and
installed at Sincan Transformer Substation-Ankara primarily for the purposes of
reactive power compensation and terminal voltage regulation. The T-STATCOM
prototype is composed of five parallel operated CMC modules developed within the
scope of this PhD thesis research work. The T-STATCOM configuration permits the
operation of any number of CMC modules in the range from one to five for
experimental purposes. The performance of this T-STATCOM system is also
presented in this PhD thesis as a sample application.
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Ungdomars identitetsskapande och livsvillkor : Fyra studier om ungdomar i fyra olika kontexterDahlgren, Erika, Jarlengrip, Karl, Jonsson, Gong, Kronblad, Christopher January 2006 (has links)
Ungdomars identitetsskapande och livsvillkor är vad vår antologi handlar om. Det vi har studerat är hur ungdomar väljer att leva i det nutida samhället. I och med de stora valmöjligheterna och människors reflexiva förmåga uppkommer ständigt rädslan att de val vi gör kanske är fel. Ungdomstiden vi tar upp i denna antologi kan ses som något specifikt avgörande för skapandet av den personliga identiteten. De teman vi kommer att behandla är unga kristna i dagens samhälle och deras tro i koppling till deras identitetsskapande, punkens betydelse för ungdomars identitet och hur samhället ser på dem, hur användandet av tekniken har påverkat unga människor med dess fördelar och nackdelar. Till sist tar vi upp unga tjejers syn på förhållanden, kärlek och sex. Vi har genom intervjuer med ungdomar i åldrarna 16-26 studerat deras syn på identitet och livsvillkor ur olika perspektiv och sammanhang.
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