Thesis (MScEng)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: See item for full text / AFRIKAANSE OPSOMMING: Sien item vir volteks

Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2007. / Cooling tower rain zone performance characteristics such as the loss coefficient and the Merkel number are evaluated and simulated. To this end the influence of drop diameter and drop deformation on the velocity, path length and cooling of single water drops are investigated. Experimental drop size and pressure drop data over a counterflow rain zone are presented and the effect of drop deformation on the pressure drop is investigated using the experimental data and CFD. Using the experimental drop size data and CFD, the performance uncertainty produced by using the Rosin-Rammler drop distribution function as opposed to the discrete drop distribution data is investigated. CFD models are developed to investigate the feasibility of modelling rain zones by assuming a constant drop diameter and to establish which diameter definition is the most representative of a particular polydisperse drop distribution. These models were used to validate the correlations for the rain zone performance characteristics proposed in literature.

Thesis (MSc)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: The binary cluster model is used to investigate the properties of exotic structures and decays in various nuclei. A simple method is described to choose the possible clusters forming within the nucleus, by assuming the nucleus consists of a mixture of up to four different core-cluster pairs. A phenomenological potential is then used, with optimized parameters, to describe the even-even 222-232Th nuclei within the binary cluster model, by calculating exotic decay half-lives, reduced electromagnetic transition probabilities, and energy spectra. After finding that all experimentally observed heavy ion emissions are predicted with the model and calculated structure observables are reproduced within good agreement of the experimentally measured values, the model was extended to include the even-even 230-234U, 236-240Pu and 222-224Ra nuclei. We found that almost all experimentally observed heavy ion emissions are predicted within the model with reasonable accuracy in the calculated halflives, and found good agreement in the other calculated structure observables. / AFRIKAANSE OPSOMMING: Die binêre bondel model is gebruik om die eienskappe van eksotiese strukture en verval in verskeie nukliedes te ondersoek. ’n Eenvoudige metode is gebruik om die moontlike bondels wat binne die nuklied vorm te kies, deur die aanname te maak dat die nuklied uit ’n mengsel van tot vier verskillende kern-bondel pare bestaan. ’n Fenomenologiese potensiaal is dan gebruik, met optimale parameters, om die ewe-ewe 222-232Th nukliedes met die binêre bondel model te beskryf, deur eksotiese verval halfleeftye, verminderde elektromagnetiese oorgangswaarskynlikhede, en energie spektra te bereken. Nadat daar gevind is dat alle vrygestelde swaar ione wat eksperimenteel waargeneem is deur die model voorspel word, en berekende struktuur waarneembares tot goeie ooreenstemming met die eksperimentele waardes produseer is, is die model uitgebrei om die ewe-ewe 230-234U, 236-240Pu en 222-224Ra nukliedes in te sluit. Daar is gevind dat byna alle vrygestelde swaar ione wat eksperimenteel waargeneem is deur die model voorspel word met redelike akkuraathied in die berekening van hul halfleeftye, asook dat daar goeie ooreenstemming tussen die berekende en eksperimentele waardes van ander struktuur waarneembares was.

Syftet med denna studie är att söka kunskap om omsorg genom att prata med förskollärare om lämningssituationer. Vi kartlägger, utforskar och fördjupar deras omsorgskunskap, var den kommer ifrån och var de placerar den i förskollärarprofessionen. Genom att ha fenomenologi som teoretisk utgångspunkt, söker vi essensen av deras kunskap genom att ta del av hela deras livsvärld. Vi använder oss också av Aristoteles kunskapsbegrepp fronesis, för att analysera vårt material. Syftet med det är att vidga normer för kunskap och professionalitet. Vårt resultat visar att essensen i förskollärares kunskaper vid lämningssituationer består av inkännande och lyhördhet eftersom varje situation och barn kräver olika bemötanden utifrån de behov som uppstår. Vi har upptäckt att dethär är en kunskapsform som har en inneboende logik som baseras på ett omsorgsetiskt förhållningssätt. Detta ser vi som vårt viktigaste resultat. Vår slutsats blir därför att omsorg är en kunskapsform som tillhör förskollärarprofessionen som bör inkluderas i förskolans kunskapsbank. Förskolans pedagogik består av omsorg, lärande och fostran och ska samtidigt vila på vetenskaplig grund och därför blir det viktigt att alla dessa delar undersöks och formuleras på ett vetenskapligt vis. / The purpose of this study is to seek knowledge about care by interviewing preschool teachers regarding daily drop-offs. We have explored what this knowledge consists of, where it comes from and how they apply it in their profession at large. By using phenomenology as our theoretical approach, we seek the essence of their knowledge by including their whole lived experience. We also use Aristotle’s concept fronesis, to analyze our material. By doing this we aim to broaden standards of knowledge and professionality. Our results show that the essence of the preschool teachers´ knowledge in the situation of daily drop-offs, comes down to the their empathetic and responsive ability, since every child and situation requires a different approach, depending on the childs different needs. We discovered that this is a form of knowledge owning its’ own logic, based on ethics of care, which we see as our most important result. Our conclusion is therefore, that caring is a form of knowledge that is a part of the preschool teacher profession and should also be included as one. Pedagogy in Swedish preschools integrates an educational and caregiving practice and should also be based on scientific methods and evidence-based practices. It is important that the educational aswell as the caregiving element become subjects of scientific research.

In the recent past it has been found that a considerable pressure drop occurred during the extrusion of linear polyethylene in the course of capillary flow. The pressure drop resides within a narrow temperature window of one to two degrees Celsius. In this research the hydrodynamic condition and molecular origin of the extrusion window of linear polymer were investigated further. The advantage of the extrusion window, viz. smooth extrudate with less die swell ratio attained at low extrusion pressure and temperature, has potential in industrial applications. However, the extrusion window, corresponding to linear polyethylene (PE) with relatively low polydispersity (<7), has a narrow window temperature interval, circa 1~2°C, thus it could not be applied to industrial scale processing at the industrial scale. To have a fundamental insight and make the process industrially viable, research in this thesis was devoted to broaden the extrusion window to tolerate the thermal fluctuations in conventional processing. To achieve this goal molecular weight dependence of window temperature and flow criticalities is revealed. The hydrodynamic conditions of the extrusion window observed in a rate-controlled rheometer and stick-slip flow studied in a stress-controlled rheometer could be traced back to the same origin, viz. slip flow arises due to the disentanglement of adsorbed chains on capillary wall from free chains in the bulk. Secondly, a dual window effect was uncovered in the course of capillary flow of a bimodal PE, which is consistent with the window temperature dependence on molecular weight. Moreover, it was found that flow induced orientation within the window effect is even less than that observed in steady state flow at a relatively low shear rate. This implies that in the window region only relaxed free chains are extruded through the capillary die and most of the adsorbed chains, which could be disengaged from the entangled melt, remain sticking to the inner capillary wall. This observation is consistent with the hydrodynamic origin of high-surface-energy-die slip flow. Finally, a unimodal linear PE with extremely broad molecular weight distribution, i.e. polydispersity (PDI) is 27, showed a broad window effect, circa 8°C, at an appropriate apparent shear rate. The molecular origin of such a broad window effect is due to its broad molecular weight distribution. These results have further implications for energy efficient processing.

No description available.

I denna uppsats försöker jag att fylla ett tomrum inom forskningen om studenter som väljer att hoppa sina programutbildningar inom samhällsvetenskapliga program riktade mot en kandidatexamen. Syftet med detta arbete är att presentera en bild av avhoppade studenter inom kandidatprogram, och därmed utgöra en beskrivande studie för fortsatt forskning och fördjupning inom området. Jag har samlat in och analyserat statistik om avhoppade studenter från fem samhällsvetenskapliga program vid Luleå tekniska universitet. Med hjälp av statistisk analys ger jag en detaljerad bild av studenterna som väljer att hoppa av sin samhällsvetenskapliga universitetsutbildning. Resultaten visar på en skillnad mellan könen, där männen generellt är underrepresenterade inom de flesta program men har samtidigt högst sannolikhet att lämna programmen. För båda könen är det inte ovanligt att de fortsätter studera ett annat program eller kurser vid samma universitet efter att de har hoppat av. Denna sannolikhet ökar ännu mer ifall de ursprungligen kommer från närliggande orter till universitetet. För avhoppade studenterna som kommer från andra delar av Sverige råder det omvända förhållandet, om dessa individer fortsätter att studera sker det oftast vid ett annat universitet eller högskola. Med de tillgängliga data som använts går det dock ej utläsa ifall de avhoppade studenterna väljer att studera liknande program eller kurser vid nya utbildningsorter. Det finns även en skillnad mellan könen när man gör en åldersindelning, där äldre kvinnor oftare forsätter att studera än män. Jag diskuterar mina resultat med hjälp av etablerad forskning inom utbildningssociologi, där man studerat hur kulturellt kapital, habitus, könsskillnader påverkar engagemang gentemot skolan och hur väl man lyckas prestera inom skolväsendet. Genom att koppla resultaten mot teorier inom utbildningssociologi kan detta arbete vara en utgångspunkt för att utveckla nya frågeställningar och hypoteser om avhoppade kandidatprogram studenter. Och därmed bidra till fortsatt forskning inom området. / In this paper I try to fill a gap in the studies of students who drop out of higher education in Sweden. The gap consists of students who choose to drop out of educational programs aimed towards bachelor degrees in the social sciences. The aim of this study is to present the reader with a picture of students who drops out of bachelor programs and by doing so I hope to provide a stepping stone for further research in this area. I collect and analyze statistical data on drop outs from five programs at the University of Technology in Luleå. With this I provide detailed presentation using statistical analysis of the students who choose to drop out of higher education in the social sciences. The analyzed data shows a discrepancy between the genders, where even though men are typically underrepresented at the programs at a whole, they are still the most likely to leave the programs. But even when they drop out of a program there is a high probability that they continue to study at the same university, this is true for both gender but slightly more so for women. This also increases greatly if you are from the surrounding area of the university to begin with. For students who drop out and originated from other parts of the country, they are more likely to continue their studies at a different university. With the current data available in this study, there is no way to know what type of programs or courses they choose to study at their new choice of university. There is also a difference between the genders when accounting for age, where older women have a slightly higher tendency to continue to study after they drop out.  I discuss my results with established research in the field of sociology of education, on how culture capital, habitus, and differences in gender effect how students engage and perform in education. By using theories of sociology of education, this study can be used to further develop research questions and explore new premises within the subject area.

Questa tesi è una raccolta di due capitoli che indagano due temi distinti di ricerca in economia del lavoro e dell'istruzione. Nel primo capitolo, si studiano gli effetti causali di una nuova politica di ammissione selettiva introdotta presso il Dipartimento di Economia di una importante università private situata nel nord d'Italia. Si trovano significativi miglioramenti nei risultati accademici degli studenti del primo anno che sono esposti alla nuova politica di ammissione in termini di una riduzione del tasso di abbandono scolastico e di un aumento dei crediti compiuti. Nel secondo capitolo di questa tesi, da un'altra parte, si fornisce un'evidenza recente sulla struttura dinamica e di autocovarianza del reddito di lavoro maschile italiano e si caratterizzano gli shock sul reddito del lavoro per tutto il ciclo di vita sfruttando dei dati amministrativa di grande scala provenienti dagli archivi dell'INPS. Osserviamo un aumento sostanziale della varianza del reddito degli individui di età compresa tra 50 e 60 anni. Tali risultati suggeriscono che questo aumento della varianza è guidato dall'aumento della varianza sia del componente transitorio che permanente della disuguaglianza di reddito. Tuttavia, l'accelerazione per gli individui sopra i 50 anni è causato dalla fluttuazione della varianza dei shock transitori. / This thesis is a collection of two chapters that investigate two different research topics in labor and education economics. In the first chapter, we study the causal effects of a new selective admission policy introduced in the Department of Economics at a leading private university located in the North of Italy. We find significant improvements in the academic outcomes of first year students who are exposed to this new admission policy in terms of reduction in the drop-out rate and increase in the average credits. In the second chapter of this thesis, on the other hand, we provide up-to-date evidence on the dynamic and autocovariance structures of Italian males' labor income and characterize labor income shocks over the life-cycle by exploiting a large-scale administrative data from the archives of Italian Social Security Administration (INPS). We observe a substantial increase in the variance of log-incomes of individuals between the ages of 50 and 60. Our results suggest that the latter increase in the variance is driven by the increases in the variances of both transitory and permanent components of income inequality. However, the accelerating pattern after age 50 is caused by the fluctuations in the variance of transitory shocks.

本研究旨在探討國中補校學生中輟的原因及其有關之變項；並對中輟原因的因應策略進行相關之研究。研究的方法採用文獻探討及問卷調查。研究的範圍為100至102學年度間，曾就讀補校且仍未復學之中輟生，由新北市境內辦理國中補習教育的30所國中，擇17所國中補效實施問卷。將實際收集的有效資料與以分析，得到下列幾項重要的發現及結論； 一、影響國中補校學生中輟的原因多元且複雜，以工作、家庭、自我能力認同、生理、心理及學校等因素居多。 二、國中補校學生中輟最主要原因，乃是工作及家庭因素。 三、學校因素在國中補校學生中輟原因中，在各因素之後。 四、不同個人背景變項之國中補校中輟生，其中輟原因與性別、年齡、婚姻及居住地區有關。 五、因應國中補校學生中輟生的策略，改善教師教學應被視為最重要且須立即進行之因應策略，並輔以加強學生輔導，改善環境與設備，調整課程與內容等策略。 六、在國中補校學生中輟的因應策略上，教師及學生的看法頗為一致。 / The purpose of this study is to explore the cause of dropouts among junior high school extention school (JHSES) students, their related variables and the coping strategies to such dropouts. Methology of research document analysis and questionnaires were performed in the 100-102 school year. Among 30 JHSES in New Taipei City, 17 enrolled in the questionnaire. Following important conclusions were obtained from data collected: 1. Factors influencing JHSES student dropout are diverse and complex, involving work, family, self-identity, physical, psychological and school, among others. 2. Most important factor of JHSES dropout is work and family. 3. School is least influential in the JHSES dropout. 4. JHSES dropout with different personal background is most effected by gender, age, marital status and residential areas. 5. Improvement of teacher instruction should be regarded as most important and immediate strategy, supplemented by strengthening student counseling, improving environment and equipment, adjusting curriculum content, etc. 6. Teacher and student views are consistent in the strategies to improve dropout in JHSES.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.