• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 324
  • 235
  • 71
  • 40
  • 35
  • 20
  • 9
  • 6
  • 6
  • 6
  • 5
  • 4
  • 2
  • 2
  • 2
  • Tagged with
  • 909
  • 198
  • 155
  • 126
  • 103
  • 101
  • 89
  • 79
  • 77
  • 76
  • 58
  • 53
  • 48
  • 48
  • 47
  • 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.
121

Characterization and Combustion Performance of Corn Oil-Based Biofuel Blends

Savant, Gautam Sandesh 2012 May 1900 (has links)
In recent years, the development and use of biofuels have received considerable attention due to the high demand for environmentally acceptable (green) fuels. Most of the recent studies have looked at the processes of converting vegetable oils into biodiesel. It is well known vegetable oil to biodiesel conversion involves many processes including transesterification, which makes biodiesel costly and time-consuming to produce. In this study, the effects of blending high-viscosity fresh and used corn oils with low-viscosity diesel and jet fuel mixed with butanol and ethanol were studied. Several corn oil-based blends were formulated and characterized to understand the effect of composition on viscosity, fuel stability and energy content. The formulated corn oil blends were combusted in a 30 kW modified combustion chamber to determine the corresponding NOx and CO emission levels, along with CO₂ levels. Used corn oil was made by simply heating fresh corn oil for a fixed period of time (about 44 hours), and was characterized by quantifying its total polar material (TPM), iodine value, free fatty acid content, and peroxide value. The combustion experiments were conducted at a constant heat output of 68,620 kJ/hr (19 kW), to observe and study the effects of equivalence ratio, swirl number, and fuel composition on emissions. Used corn oil blends exhibited better combustion performance than fresh corn oil blends, due in part to the higher unsaturation levels in fresh corn oil. NOx emissions for used corn oil increased with swirl number. Among all the blends, the one with the higher amount of diesel (lower amount of corn oil) showed higher NOx emissions. The blend with fresh corn oil showed decreasing NOx with increasing equivalence ratio at swirl number 1.4. All blends showed generally decreasing CO trends at both swirl numbers at very lean conditions. The diesel fuel component as well as the alcohols in the blends were also important in the production of pollutants. Compared to the diesel-based blends mixed with used corn oil, butanol, and ethanol, the jet fuel-based blends showed higher NOx levels and lower CO levels at both swirl numbers.
122

Robust A-optimal designs for mixture experiments in Scheffe' models

Chou, Chao-Jin 28 July 2003 (has links)
A mixture experiment is an experiments in which the q-ingredients are nonnegative and subject to the simplex restriction on the (q-1)-dimentional probability simplex. In this work , we investigate the robust A-optimal designs for mixture experiments with uncertainty on the linear, quadratic models considered by Scheffe' (1958). In Chan (2000), a review on the optimal designs including A-optimal designs are presented for each of the Scheffe's linear and quadratic models. We will use these results to find the robust A-optimal design for the linear and quadratic models under some robust A-criteria. It is shown with the two types of robust A-criteria defined here, there exists a convex combination of the individual A-optimal designs for linear and quadratic models respectively to be robust A-optimal. In the end, we compare efficiencies of these optimal designs with respect to different A-criteria.
123

Synthesis Of Carbasugars And Other Related Structural Motifs

Talukdar, Pinaki 05 1900 (has links)
Recent years have witnessed a great deal of interest in the design and synthesis of small molecules, which can mimic complex carbohydrates of vital importance in various life processes. Carbasugars constitute one such class of molecules among several others, in which ring oxygen of sugar is replaced by a methylene unit. Several approaches have been reported in the literature for the synthesis of carbasugars emanating both from carbohydrate and non-carbohydrate sources. While the carbohydrate-based approaches require extensive prote'ction-deprotection maneuver, the non-carbohydrate-based approaches generally have problems of diastereoselection and introduction of chirality. In the context of synthesis of carbasugars, we envisaged that a suitable derivative of i bicyclo[2.2.1]heptane (norbornyl system), could serve as a carbasugar equivalent provided the inherent cyclohexane ring could be disengaged through a tactical cleavage of C1-C7 or C4-C7 bonds. In the present thesis entitled "Synthesis of carbasugars and other structurally related motifs", we have established the carbasugar-norbornyl system equivalence by using 7-* oxobicyclo[2.2.1]hept~5-en-2~yl acetate as precursor . While the tactical cleavage of C1-C7 bond was employed in the synthesis of carbasugars, the C4-G7 bond cleavage provided access to a new class of carbasugars i.e. "confused" carbasugars* The quest for stronger and specific inhibitors of glycosidases led us to synthesize a diverse array of polyoxygenated compounds in this new family of carbasugars. The thesis has been organized under five main sections: I. Introduction, II. Results & Discussion, III. Experimental, IV. Spectra, and V. References where we have narrated our I synthetic efforts with suitable literature citations.
124

Assessing Psychometric Equivalence of Paper-and-Pencil and Interactive Voice Response (IVR) Modes of Administration for the EQ-5D and the QLQ-C30

Lundy, John Jason January 2008 (has links)
Electronic data capture technologies, such as interactive voice response (IVR) systems, are emerging as important alternatives for collecting self-reported data. The purpose of this research was to assess the measurement equivalence between the original paper-based versions and the adapted interactive voice response (IVR) versions of the EQ-5D and the QLQ-C30. Furthermore, we examined the test-retest reliability of two consecutive administrations of the IVR versions of the EQ-5D and the QLQ-C30. The comparison of the paper and IVR versions of the EQ-5D was conducted utilizing a crossover design with subjects randomly assigned to one of two assessment orders: 1) paper then IVR or 2) IVR then paper. A convenience sample of in-treatment outpatient cancer clinic patients (n=139) were asked to complete each assessment two days apart. For the test-retest component, outpatient cancer clinic patients (n=127) were asked to complete the IVR-based EQ-5D twice, two days apart. The analyses tested for mean differences (paired t-test) and test-retest reliability (ICC).In the crossover analysis, ten of the fifteen mean differences analyzed for the scales and items of the QLQ-C30 were within the equivalence interval set a priori. The ICCs for the scales and items of the QLQ-C30 ranged from 0.698 to 0.899. Two of the items, insomnia and appetite loss, did not meet our threshold of being statistically different from an ICC of 0.70. The EQ-5D index score means were equivalent between paper and IVR, however the EQ VAS score differences were not wholly contained in the equivalence interval. The ICCs were above 0.890 for the index and the EQ VAS. In the test-retest analysis, the ICCs for the nine multi-item scales for the QLQ-C30 were all above 0.69, ranging from 0.698 to 0.891. Ten of the fifteen mean differences analyzed were within the equivalence interval set a priori. For the EQ-5D, the mean differences were wholly contained within the equivalence intervals for both the index and the EQ VAS and the ICCs were significantly different from 0.70. Overall, the IVR version of the questionnaires provided psychometrically equivalent results to those obtained on the original paper version and showed good stability over time.
125

Lietuvių kalbos frazeologizmų su komponentu „akis“ atitikmenys anglų ir rusų kalbose / Lithuanian Phraseological Units With Component „eye“ Equivalents In English And Russian Languages

Jucienė, Indra 23 June 2006 (has links)
The subject of Master`s work – Lithuanian Phraseological Units With Component „eye“ Equivalents In English And Russian Languages. 518 examples of phraseological units with component „eye“, are picked out from Lithuanian, English and Russian Dictionaries of Phraseology. These tasks are set in Master`s work: • To consider an academic material, which deals with the subject. • To pick out phraseological units with component „eye“ from Lithuanian, English and Russian Dictionaries of Phraseology. • To group phraseological units into thematic groups according to their meanings. • To do contrastive analysis of fraseological units according to their stucture and stylistic. • To group phraseological thematic groups according to their equivalence in Lithuanian, English and Russian languages. In the preface of Master`s work, the tasks of the subject are stated, academic material is analysed. In the main part of Master`s work, Lithuanian, English and Russian phraseological units with component „eye“, are contrasted and analysed according to these positions: meaning, structure, stylistic, equivalence. All phraseological units with component „eye“ in Lithuanian, English and Russian languages are grouped in 4 thematic groups according to their meaning: motion, visual, physical, psychoemotional. Lithuanian, English and Russian phraseological units are classified from the point of view of their structure and stilistic. According to their equivalents in Lithuanian, English and Russian... [to full text]
126

Polynomial Functions over Rings of Residue Classes of Integers

Meredith, M Brandon 06 August 2007 (has links)
In this thesis we discuss how to find equivalent representations of polynomial functions over the ring of integers modulo a power of a prime. Specifically, we look for lower degree representations and representations with fewer variables for which important applications in electrical and computer engineering exist. We present several algorithms for finding these compact formulations.
127

Nonparametric statistical procedures for therapeutic clinical trials with survival endpoints

Luo, Yingchun 02 August 2007 (has links)
This thesis proposed two nonparametric statistical tests, based on the Kolmogorov-Smirnov distance and L2 mallows disatnce. To implement the proposed tests, nonparametric bootstrap method is employed to approximate the distributions of the test statistics to construct the corresponding bootstrap confidence interval procedures. Monte-Carlo simulations are performed to investigate the actual type I error of the proposed bootstrap procedures. It is found that the type I error of the bootstrap BC confidence interval procedure is close to the nominal level when censoring is not heavy and the boosttrap percentile confidence interval procedure works well when Kolmogorov-Smirnov distance is used to characterize the equivalence. When the data is heavily censored, the procedures based on the Kolmogorov-Smirnov distance have very conservative type I errors, while the procedures based on the Mallows distance are very liberal. / Thesis (Ph.D, Mathematics & Statistics) -- Queen's University, 2007-08-01 10:43:32.345
128

Improving children's understanding of mathematical equivalence

Watchorn, Rebecca P. D. Unknown Date
No description available.
129

A text editor based on relations /

Fayerman, Brenda. January 1984 (has links)
No description available.
130

Expression of the concept of happiness in English and Lithuanian zoomorphic idioms / Laimės koncepto išraiška anglų ir lietuvių kalbų zoomorfiniuose frazeologizmuose

Sadauninkaitė, Skaistė 05 August 2013 (has links)
The aim of the research was to investigate the aspects of happiness and the way they are expressed through Lithuanian and English zoomorphic idioms. The research focused on the theoretical background of idiom peculiarities, establishment of the aspects of happiness, their investigation and comparison within the zoomorphic idioms of both languages. To carry out the research, 135 zoomorphic idioms were collected: 50 English idioms and 85 Lithuanian idioms. Qualitative, descriptive and quantitative methods of analysis were mainly employed in the research. The analysis revealed that 45 animal names were employed to express happiness in both languages. English idioms comprised 25 animal names, and 33 animal names were found in Lithuanian idioms. Despite the fact that 13 animal names (bull, calf, cat, cow, dog, horse, sheep, eagle, bird, dove, fish, bee, and duckling) coincided in both languages, the patterns of equivalence expressing the same aspect of happiness were not abundant. Ten semantic groups of happiness were distinguished:joy,wealth, good health, relationships,knowledge,longevity,easy life, optimism, acknowledgement, and positive traits. Although there were 3 total and 12 partial equivalents distinguished among 10 semantic groups of happiness, zero equivalence was prevailing. This confirms the fact that Lithuanian and English cultures are different. Despite this fact, both the Lithuanians and the English employ the concepts of a horse and a cat to express the aspects of... [to full text] / Šio darbo tikslas yra ištirti laimės aspektus bei jų reiškimo būdus lietuviškuose ir angliškuose zoomorfiniuose frazeologizmuose. Tyrime yra naudojami kokybinis, kiekybinis ir aprašomasis analizės metodai. Teorinėje dalyje yra apžvelgiama frazeologizmų definicijos problema, jų struktūrinė bei semantinė klasifikacija, formavimosi subtilybės bei kultūros įtaka. Šiame darbe skiriamas didelis dėmesys šiuolaikinei ir praėjusių šimtmečių laimės sampratai bei ryšio tarp žmogaus ir gyvūnų aptarimui. Praktinės dalies analizei buvo surinkta 135 zoomorfiniai frazeologizmai: 50 anglų kalboje ir 85 lietuvių kalboje. Iš viso 45 gyvūnai buvo pasitelkti reikšti laimės aspektus abiejų kalbų frazeologizmuose: 25 iš jų anglų kalboje ir 33 lietuvių kalboje. Tik 13 gyvūnų sutampa abiejose kalbose (jautis, veršis, katė/katinas, karvė, šuo, arklys, avis, erelis, paukštis, balandis, žuvis, bitė ir ančiukas). Dauguma jų yra naminiai gyvūnai, vieni iš anksčiausiai prijaukintų bei būdingi abiem šalims. Vienas iš svarbiausių praktinės dalies akcentų buvo išskirti laimės aspektų semantines grupes. Remiantis mokslininkų darbais bei statistiniais tyrimais buvo išskirta 10 semantinių grupių: džiaugsmas/sėkmė, turtas/gerovė, gera sveikata/fizinė būklė, santykiai/sutarimas, žinios/patirtis, ilgaamžiškumas/energija, lengvas gyvenimas, optimizmas/pozityvios permainos, pripažinimas, teigiami bruožai/buvimas geresniu už kitus. Remiantis šiais kriterijais, frazeologizmai buvo klasifikuojami, lyginami ir... [toliau žr. visą tekstą]

Page generated in 0.0488 seconds