• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 224
  • 179
  • 10
  • 8
  • 4
  • 3
  • 3
  • 3
  • 1
  • 1
  • Tagged with
  • 446
  • 446
  • 265
  • 265
  • 247
  • 246
  • 225
  • 224
  • 218
  • 186
  • 89
  • 81
  • 77
  • 77
  • 75
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
341

Enhanced Passive RF-DC Converter Circuit Efficiency for Low RF Energy Harvesting

Chaour, Issam, Fakhfakh, Ahmed, Kanoun, Olfa 02 May 2017 (has links) (PDF)
For radio frequency energy transmission, the conversion efficiency of the receiver is decisive not only for reducing sending power, but also for enabling energy transmission over long and variable distances. In this contribution, we present a passive RF-DC converter for energy harvesting at ultra-low input power at 868 MHz. The novel converter consists of a reactive matching circuit and a combined voltage multiplier and rectifier. The stored energy in the input inductor and capacitance, during the negative wave, is conveyed to the output capacitance during the positive one. Although Dickson and Villard topologies have principally comparable efficiency for multi-stage voltage multipliers, the Dickson topology reaches a better efficiency within the novel ultra-low input power converter concept. At the output stage, a low-pass filter is introduced to reduce ripple at high frequencies in order to realize a stable DC signal. The proposed rectifier enables harvesting energy at even a low input power from −40 dBm for a resistive load of 50 kΩ. It realizes a significant improvement in comparison with state of the art solutions
342

Experimental observation and quantum chemical investigation of thallium(I) (Z)-methanediazotate: synthesis of a long sought and highly reactive species

Singh, Neeraj, Fiedler, Benjamin, Friedrich, Joachim, Banert, Klaus 28 April 2017 (has links) (PDF)
For the first time, successful synthesis and characterisation of the missing (Z)-isomer of thallium(I) methanediazotate has been accomplished, utilising low-temperature NMR monitoring analysis. The title compound was synthesised from N-methyl-N-nitrosourea and thallium(I) propoxide, under sub-ambient temperature conditions, as a highly moisture sensitive entity. Quantum chemical calculations, performed at the CCSD(T) level, depict excellent conformity to experimental results. Indeed, compared to its (E) counterpart, the formation of the title compound is thermodynamically less favoured, but preferred by means of kinetic control owing to a hindered isomerisation.
343

Cognitive Investments in Academic Success: The Role of Need for Cognition at University

Grass, Julia, Strobel, Alexander, Strobel, Anja 26 June 2017 (has links) (PDF)
Previous research has shown that Need for Cognition (NFC), the individual tendency to engage in and enjoy cognitive endeavors, contributes to academic performance. Most studies on NFC and related constructs have thereby focused on grades to capture tertiary academic success. This study aimed at a more comprehensive approach on NFC’s meaning to success in university. We examined not only performance but also rather affective indicators of success. The current sample consisted of 396 students of different subjects with a mean age of 24 years (139 male). All participants took part in an online survey that assessed NFC together with school performance and further personality variables via self-report. Success in university was comprehensively operationalized including performance, satisfaction with one’s studies, and thoughts about quitting/changing one’s major as indicators. The value of NFC in predicting tertiary academic success was examined with correlation analyses and path analysis. NFC significantly correlated with all success variables with the highest correlation for study satisfaction. Path analysis confirmed the importance of NFC for study satisfaction showing that NFC had a significant direct effect on study satisfaction and via this variable also a significant indirect effect on termination thoughts. This study clearly indicates that NFC broadly contributes to the mastery of academic requirements and that it is worthwhile to intensify research on NFC in the context of tertiary education.
344

Retention of employees in the institutions of higher learning with special reference to the Central University of Technology : Free State

Moeketsi, Maganyane Mittah 11 1900 (has links)
The research investigates the retention of employees in the institutions of higher learning and the focus is placed on the Central University of Technology: Free State (CUT). The research is undertaken because the employees at the Central University of Technology: Free State, are resigning from their positions and join rival institutions and other organisations. This creates a problem on part of students, fellow employees and management. There is therefore, a need to find reasons behind these mass resignations of employees and also to look at the retention strategies that can be employed to keep employees at the Central University of Technology: Free State. In order to address the above purpose of the research, various retention strategies to keep talented employees are discussed, and factors that lead to employees leaving the institutions are also placed under the spotlight. The discussion shows that talent management has a direct relationship with employee needs and motivation. Qualitative and quantitative methods of research are used to analyse the retention strategies employed at the Central University of Technology: Free State. The findings of the research reveal that factors such as working environment, satisfying work-life, personal career development, emotional exhaustion as well as rewards versus performance exacerbate mass exodus of talented employees at the institution. It is also disclosed that there are retention strategies in place but are not effectively implemented. The findings revealed that managers and supervisors play crucial roles in the interpretation and implementation of strategies. Working conditions should be improved so that employees stay with the institution and perform to the best of their ability. Training should be made compulsory for every employee as it provides necessary skills. Best performance and rewards should match performance in order to keep employees at the institution. / Public Administration and Management / M. Admin. (Public Administration)
345

Application of multivariate regression techniques to paint: for the quantitive FTIR spectroscopic analysis of polymeric components

Phala, Adeela Colyne January 2011 (has links)
Thesis submitted in fulfilment of the requirements for the degree Master of Technology Chemistry in the Faculty of (Science) Supervisor: Professor T.N. van der Walt Bellville campus Date submitted: October 2011 / It is important to quantify polymeric components in a coating because they greatly influence the performance of a coating. The difficulty associated with analysis of polymers by Fourier transform infrared (FTIR) analysis’s is that colinearities arise from similar or overlapping spectral features. A quantitative FTIR method with attenuated total reflectance coupled to multivariate/ chemometric analysis is presented. It allows for simultaneous quantification of 3 polymeric components; a rheology modifier, organic opacifier and styrene acrylic binder, with no prior extraction or separation from the paint. The factor based methods partial least squares (PLS) and principle component regression (PCR) permit colinearities by decomposing the spectral data into smaller matrices with principle scores and loading vectors. For model building spectral information from calibrators and validation samples at different analysis regions were incorporated. PCR and PLS were used to inspect the variation within the sample set. The PLS algorithms were found to predict the polymeric components the best. The concentrations of the polymeric components in a coating were predicted with the calibration model. Three PLS models each with different analysis regions yielded a coefficient of correlation R2 close to 1 for each of the components. The root mean square error of calibration (RMSEC) and root mean square error of prediction (RMSEP) was less than 5%. The best out-put was obtained where spectral features of water was included (Trial 3). The prediction residual values for the three models ranged from 2 to -2 and 10 to -10. The method allows paint samples to be analysed in pure form and opens many opportunities for other coating components to be analysed in the same way.
346

Use of food-buying practices within different socio-economic classes in the city of Cape Town

Harper, Crystal January 2013 (has links)
Thesis submitted in fulfilment of the requirements for the degree Master of Technology Consumer Science: Food and Nutrition in the Faculty of Applied Sciences at the Cape Peninsula University of Technology 2013 / Consumer debt has escalated in South Africa ever since the country sank into a recession in early 2009. One of the many consequences of this economic downturn has been a major increase in energy, transport and food prices. Food-buying strategies can be used by consumers to help to reduce the amount of money, which is spent on food, and increase funds that are available for other household expenses. The main objective of this study was to determine the use of four pre-selected food-buying practices by consumers who reside in different socio-economic status (SES) areas in the City of Cape Town. Residents of lower SES areas have been found to have purchasing patterns that are different to those who live in higher SES areas. The subsidiary objectives were to further establish whether there is a difference in the use of food-buying practices by consumers who reside in different SES areas, and to ascertain whether shopper and demographical characteristics have an influence on the use of food-buying practices among consumers in general as well as among consumers within the same SES area. A consumer intercept survey was conducted after being granted ethics approval. Three groups of respondents that represent a low, middle and high SES area were systematically sampled. A total of 1 200 consumers (95% response rate) who are older than 18 years anonymously and voluntarily participated in the study, which was conducted at pre-selected stores in the suburban areas of Delft (low SES area), Maitland (middle SES area) and Meadowridge (high SES area) in the City of Cape Town. These areas and stores were selected to represent the SES of households or consumers, respectively, based on the demographic and employment profile that was provided for each by Statistics South Africa‟s 2001‟s census profiles. The data was collected by using a pilot tested structured, self-administered questionnaire consisting of mainly multiple-choice questions, which gathered information from the respondents regarding their shopper and demographic characteristics, as well as their frequency of use of the four food-buying practices (represented by six structured questions each) as: (i) use of a shopping list; (ii) use of advertisements to plan shopping; (iii) comparison of prices amongst different brands; and (iv) avoidance of impulse buying. These food-buying practices were selected based on available consumer education literature, which focused on the use of these food-buying practices and a pilot study that was conducted in 2011, which indicated that these four practices were most frequently used by the consumers who were surveyed. Within each SES area most of the Cronbach‟s alpha coefficients that were obtained were >0.9 among the six questions, which represented each food-buying practice, and reflected strong internal consistencies among the questions. The Generalised Linear Model analysis of variance utilising the Wald statistic, which is based on the chi- square distribution and Bonferroni pair-wise comparisons, were used to determine significant differences between respondents‟ use of the food-buying practices and their SES area group, as well as their shopper and demographic characteristics. A significant level of p<0.001, as well as p<0.05 was used. Most (60 to 80%) of the respondents in each SES area are female. Within the total sample, low and middle SES areas a majority (62 to 73%) of the respondents were between 26 to 55 years of age, whereas in the high SES area a majority (63.5%) of the respondents were 46 years and older. In general, more than half (52 to 56%) of the respondents were married and most (38 to 55%) were employed full-time and had household sizes, which mainly (18 to 23%) consist of two to four members. Regarding highest level of education attained, most of the respondents in the total sample either had a Grade 8 to 11 (37.6%) or a Grade 12 (24.7%), whereas most (54%) respondents in the high SES had either acquired a post-matric diploma or certificate, degree or post-graduate degree. Most (67 to 89 %) of the respondents within the total sample, middle and low SES area associated themselves with the Coloured population group, whereas most (56.7%) of the respondents in the high SES area associated themselves with the White population group. Concerning household monthly income, two thirds (65%) of the respondents within the high SES area had an income of R12 801 upward; most (77.5%) of the respondents within the middle SES area had an income of R801 to R12 800 per month; and more than half (57%) of the respondents in the low SES area received an income of R800 to R3 200 per month. In general, most respondents indicated that they shopped for food once a week (33 to 48%); took less than half an hour to shop for food (40 to 52%); and usually shopped alone for food (68.9%). Cash was the most prevalent means of payment among respondents within the total sample (66.7%), middle (70.5%) and low (93%) SES areas, while most (43.2%) respondents in the high SES area paid by means of a debit card. Among the respondents who reside in the different SES suburban areas, differences in the use of food-buying practices were revealed. Respondents within the high (p<0.001) and middle (p<0.05) SES areas displayed a higher propensity to use a shopping list, yet a lower propensity to use advertisements compared to respondents within the low SES area. Respondents within the low and particularly middle SES area displayed a higher propensity to compare prices (p<0.05) compared to respondents within the high SES area. No differences (p>0.05) for the avoidance of impulse buying as a food-buying practice were found among respondents within a low, middle and high SES area. A largely low propensity to avoid impulse buying was found. Regarding shopper characteristics, the respondent payment method influenced the use of a shopping list (p<0.05), use of advertisements (p<0.05 and p<0.001 between the payment methods) and propensity to avoid impulse buying (p<0.05) as food-buying practices within the low SES area. Among respondents, in general, the payment method influenced the avoidance of impulse buying (p<0.05) as a food-buying practice. The length of time that it took to shop influenced the use of a shopping list (p<0.05) as a food-buying practice within the low SES area and the propensity to compare prices of different brands (p<0.05) as a food-buying practice within the middle SES area. Shopping frequency influenced the use of advertisements (p<0.05) as a food buying practice within the low SES area and co-shopping influenced the propensity to avoid impulse buying (p<0.05 and p<0.001 between the various co-shoppers) as a food-buying practice within the low SES area, as well as the propensity to use advertisements (p<0.05) as a food-buying practice within the high SES area. Gender influenced the use of a shopping list (p<0.05) as a food-buying practice within the high SES area and the use of advertisements (p<0.05), as well as the propensity to avoid impulse buying (p<0.001) as food-buying practices within the middle SES area. Gender also affected the propensity to compare the prices of different brands (p<0.05) as a food-buying practice within the low SES area and among respondents, in general, the propensity to avoid impulse buying (p<0.05), as well as the use of advertisements (p<0.001) as food-buying practices. Employment status affected the use of a shopping list (p<0.05) as a food-buying practice within the high SES area. Population group affected the propensity to use advertisements as a food-buying practice within the low SES area (p<0.05 and p<0.001 between the population groups) and among the respondents, in general, (p<0.05). Household monthly income affected the propensity to compare the prices of different brands (p<0.05) as a food-buying practice within the high SES area. Among the respondents, in general, household monthly income affected the propensity to compare the prices of different brands (p<0.05 and p<0.001 between the income groups) and the use of advertisements (p<0.05) as food-buying practices. The study confirmed that there are differences in the use of food-buying practices among consumers who reside in different SES areas, and further identified specific shopper and demographic characteristics that have an effect on consumers‟ (in general, as well as within the same SES area) use of food-buying practices. Since food-buying practices can be used by consumers to manage their household income expenditure on food, consumer awareness of these practices, in particular the avoidance of impulse buying should be promoted through educational efforts ideally by food retail companies. These companies have the resources and capability to communicate with consumers regularly (while shopping in-store), and can inform their customers about food-buying practices that would help them to save money and/or make additional funds available for other essential household expenses.
347

In vitro propagation of Agathosma betulina an indigenous plant of economic importance

Witbooi, Hildegard January 2013 (has links)
Thesis submitted in fulfilment of the requirements for the degree Master of Technology: Horticultural Sciences in the Faculty of Applied Sciences at the CAPE PENINSULA UNIVERSITY OF TECHNOLOGY Supervisor: Dr L Kambizi Co-supervisor: Dr NP Makunga Cape Town December 2013 / Agathosma betulina (Berg.) Pillans, previously known as Barosma betulina, is a member of the Rutaceae family, and indigenous to the fynbos botanical biome of the Western Cape of South Africa. It is commonly known as buchu. Extracts as well as powdered leaves have traditionally been used for the treatment of various ailments. The increase in the international demand for A. betulina for health as well as food and beverage benefits, have raised concerns over exploitation of wild populations and the lack of horticultural information necessitates this study to evaluate the propagation of this economical important species. The main objective of this study was to establish a simple and highly productive micropropagation protocol for A. betulina through experimenting with nodal explants. Testing of the effect of various treatments (physical scarification, chemical scarification, GA, stratification, smoke and combinations thereof) on the in vitro germination of A. betulina seeds was done to elucidate the factors which control seed germination. The study revealed that the physical scarification and smoke-induced germination had a significant effect on germination percentages. In terms of germination rate, the radical generally started to appear after approximately 10 days in the physical scarification with smoke treatment. Initial decontamination methods with the exposure of various concentrations of NaOCl gave fatal results, however 1.5% NaOCl had more phenolic reactions rather than fungal or bacterial contamination. Interestingly, contamination rates of explants were influenced by the stage of maturity of the explant material. This plant material was used to test different strengths of regeneration media, to ensure that the explants receive ample nutrients. Results made exhibited that ½ MS was the best strength for growing A. betulina nodal explants. Compared comparison between in vitro derived explants and ex vitro collected explants showed that the ex vitro derived explants had significant results, but the explants lost vigour soon after the initial exponential growth leading to the explants dying off. Furthermore, ex vitro decontaminated plant material was not economically viable to continue with. Seedlings derived from germinated seeds appeared to be the preferred method of propagation as this spent the least time in culture and produced a stable plant with an established root system, which is essential during the hardening off process after in vitro growth. When exposing nodal explants to phytohormone 2,4-D it responds best to dosages 0.5mg Lˉ¹ and 1mg Lˉ¹. Phytohormone BA was very effective in producing soft friable callus. The best results were shown when 0.5mg Lˉ¹ BA was applied to ½ MS media. For both shoot length and multiple shoot production, a combination of phytohormones BA-NAA (1: 0.5mgLˉ¹) had the most significant results. Interestingly, a higher phytohormone concentration of NAA is necessary to develop multiple adventitious roots. The effect of 3mg Lˉ¹ was significant in that it resulted in multiple adventitious roots, but fewer calli was observed in this treatment. Micropropagation becomes valuable as little attention between subcultures is needed; making it less labour intensive compared to conventional nursery propagation systems where weeding watering and spraying of plants are labour intensive. In the traditional world of medicine, more so in Southern Africa, extracts are prepared by adding boiling water to the plant material; however commercial ethanol is used as an extractant. Establishment of the essential oil quality of the in vitro cultures post exposure to various treatments was done. Analysis of essential oils from A. betulina resulted in the identification of twenty one compounds. The results showed qualitative as well as quantitative differences amongst the samples used in the study. The highest relative concentration of limonene was observed in the callus of nodal explants after it was exposed to 0.5mg lˉ¹ NAA. No pulegone was found in this treatment making it ideal for limonene production. This suggests that liquid culture with the same treatment may produce more calli making it ideal for the production of limonene.
348

Evaluating an information literacy intervention for first year engineering students at the Cape Peninsula University of Technology

Marion Davids January 2009 (has links)
<p>The aim of the research project is to investigate the effectiveness of an information literacy intervention for first year engineering students at the Cape Peninsula University of Technology. Information literacy has been identified as a necessary outcome of tertiary education. It refers to the life-long learning competencies of finding and using information in order to solve problems, to make decisions and to create new knowledge. Information literacy education has evolved from earlier forms of library user education, such as bibliographic instruction, and is central to the mission of academic libraries. However, librarians responsible for information literacy programmes seldom evaluate the effectiveness of their interventions. In today&rsquo / s climate of accountability and outcomes-based education, it is necessary to provide evidence of the benefits of the user education that libraries provide. The researcher uses the American College and Research Library (ACRL) Information Literacy Competency Standards for Higher Education, which are internationally recognized and widely used by South African academic librarians, as a benchmark to evaluate an intervention for a group of first year students enrolled for a mechanical engineering course. The intervention consists of two workshops which aim to teach the students to find information relevant to their essays via the university&rsquo / s OPAC, various engineering databases and to teach them how to reference and cite their sources in their essays. The research methodology assessed students&rsquo / information literacy before and after the two workshops with the use of a questionnaire consisting of a set of questions based on some of the ACRL standards. The questionnaire also gathered data on students&rsquo / prior experience of libraries, reading and computers, which might impact on their information literacy...</p>
349

Finanzierung von Open Access - bisher und heute / Open-Access-Funding - so far and now

Blumtritt, Ute 17 June 2013 (has links) (PDF)
Die Universitätsbibliothek Chemnitz bietet seit vielen Jahren verschiedene Services zum Open-Access-Publizieren für die Wissenschaftler der Technischen Universität. Dazu gehören u.a. das digitale Volltextarchiv, das Open Journal System und der Universitätsverlag. Wissenschaftliche Autoren können sowohl auf dem Goldenen als auch auf dem Grünen Weg Open Access publizieren. In diesem Jahr wurde erstmals ein Publikationsfonds für die Veröffentlichung von Open-Access-Artikeln eingerichtet. Es wurden Mittel von der Deutschen Forschungsgemeinschaft und der Technischen Universität Chemnitz bereitgestellt. Damit können die Universitätsangehörigen die finanzielle Übernahme von Publikationsgebühren für Open-Access-Artikel bei der Bibliothek beantragen. Sind die Fördervoraussetzungen erfüllt, erfolgt der Zuschlag in der Reihenfolge des Eingangs der Rechnung. / Since many years the University Library of Chemnitz offers several services regarding open access publication to the scientists of Chemnitz University of Technology. Among others this includes a digital archive, a Journal Management System, and the University Press. It is possible to publish on Golden Way of Open Access as well as on Green Way. This year we offer for the first time a publication funds for the publication of open access articles. The financial resources are provided by Deutsche Forschungsgemeinschaft and Chemnitz University of Technology. Please apply for financial support at the University Library if you need to pay a publication fee for open access articles. If the criteria for financial support are met an agreement will be made in order of invoices received.
350

Volltextarchiv und Dokumentenserver MONARCH

Blumtritt, Ute, Ziegler, Christoph 19 December 2002 (has links)
Vorstellung des Volltextarchivs MONARCH der Technischen Universität Chemnitz. Auf der Basis von Betriebs- und Entwicklungsprinzipien wird MONARCH aus Nutzer- und Bibliothekssicht charakterisiert. Speziell wird auf die Aspekte eines Autors/Archivierenden eingegangen, z.Bsp. workflow und Statistik. Im zweiten Teil werden Interna dargelegt, wie Integration in die Gesamt-DV-Technologie, Verwendung von Standards und Basis-Werkzeugen sowie aktuelle Weiterentwicklungen.

Page generated in 0.0998 seconds