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1
Zuehlke, Karl William. "Yield." College Park, Md.: University of Maryland, 2009. http://hdl.handle.net/1903/9339.
Testo completoAbstract (sommario):
Thesis (M.F.A.) -- University of Maryland, College Park, 2009.<br>Thesis research directed by: Dept. of English. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
2
Christensen, Justin. "Electron Yield Measurements of High-Yield, Low-Conductivity Dielectric Materials." DigitalCommons@USU, 2017. https://digitalcommons.usu.edu/etd/6694.
Testo completoAbstract (sommario):
Materials exposed to the space plasma environment acquire electric charge, which can have harmful effects if it leads to arcing or electrostatic breakdown of important spacecraft components. In fact, spacecraft charging is the leading environmentally induced cause of spacecraft anomalies. This study focuses on measuring electron yield, a property of materials that describes how many electrons are ejected from a material under energetic electron bombardment, which can vary depending on the energy of incident electrons. Intrinsic electron yield is defined as the average number of electrons emitted per incident electron from an electrically neutral material. The specific aim of this work is to improve yield measurements for insulator materials, which can be difficult to test using conventional methods due to charge accumulation in insulators.Most studies of electron yield use a steady current electron beam in a vacuum chamber to irradiate materials to be tested. By comparing the amount of current deposited in the material to the total incident current, the emitted current can be calculated. This works well for conductors; however, insulators charge up quickly, which either repel incident electrons or reattract emitted electrons producing erroneous yield measurements. This study improves on methods that use a pulsed electron beam to measure yield with small amounts of charge per pulse, as well as neutralization methods to dissipate stored charge between pulse measurements.The improvements to instrumentation and data analysis techniques are quantified to demonstrate their validity. These improvements will allow for continued studies on extreme insulator materials. Future studies will provide new understanding of interactions between electron radiation and materials, which will allow for better modeling of spacecraft charging and the development of materials that meet desired electron emission specifications.
3
German, Guy. "Yield-stress drops." Thesis, University of Edinburgh, 2010. http://hdl.handle.net/1842/3792.
Testo completoAbstract (sommario):
The behaviour of viscoplastic drops during formation and detachment from a capillary nozzle, free-fall, impact on a solid substrate and subsequent spreading are investigated experimentally by high-speed imaging. Drop dynamic behaviour is an integral component of many contemporary industrial processes ranging from fuelinjection systems in combustion engines to spray coating, agrochemical and pharmaceutical delivery, fire extinguishment and ink-jet printing. Yield-stress fluids are commonly used nowadays in products ranging from mayonnaise to hair-gel. It is hoped that through understanding the dynamics of viscoplastic fluids, additional spray applications can be developed that will help to advance and optimise industrial processes. Viscoplastic fluids exhibit shear-thinning behaviour when the applied stress exceeds a certain threshold value, called the yield-stress. Below this threshold however, the fluid behaves like an elastic solid. By comparing the behaviour of viscoplastic drops with both Newtonian and shear-thinning fluids, yield-stress is shown to be capable of altering detachment behaviour, drop shape during free-fall, impact morphology and the final sessile shape of drops after spreading. For drops attached to the end of a capillary tube, growth continues until a maximum supportable tensile stress is reached in the drop neck. After this critical point, drops become unstable and detach. The critical break-up behaviour of low yield-stress drops is found to be similar to those of Newtonian and shear-thinning fluids. Above a threshold value however, characterised in terms of the ratio between yield-stress magnitude and capillary pressure, yield-stress forces exceed surface tension forces and the maximum tensile stress achievable in the drop neck at critical stability is governed by the extensional yield-stress, established using the von Mises criterion. This threshold value can also be used to characterise equilibrium drop shapes during free-fall. Whereas Newtonian, shear-thinning and low yield-stress fluids form near spherical equilibrium drop shapes, fluids above a threshold value become increasingly more prolate as the yield-stress increases. Upon impact, viscoplastic drops can exhibit central peaks at the end of inertial spreading. The influence of yield-stress magnitude on impact behaviour is qualitatively established by measuring the size of these peaks. Peaks indicate that deformation during impact is localized and within a threshold radius, shear stresses will not be large enough to overcome the yield-stress, therefore fluid within this region will not deform from the drop shape prior to impact. After impact, spreading will be dependent on the surface energy. Again, the ratio of the yield-stress magnitude to the capillary pressure can be used to characterise the final sessile drop shape. Whilst the equilibrium contact angle of Newtonian, shear-thinning and low yield-stress drops is independent of the yield-stress magnitude, above a threshold value, contact angles vary as a function of yield-stress magnitude. Whilst the research presented in this thesis highlights how fluid yield-stress can influence drop dynamics, some results are only qualitative. To establish more quantitative results, computational fluid dynamics methods should be used to examine viscoplastic drop dynamics. This research should focus primarily on impact behaviour, an aspect that has not received much attention previously. Modelling shear-thinning and viscoplastic fluid behaviour can be achieved by incorporating the relevant rheological models into the flow equations and examining impact morphology using a volume of fluid method. Numerical results can then be directly compared with the experimental results. Useful further experimentation could examine the relaxation behaviour of diamagnetically levitated viscoplastic drops. The results from this work could provide further insight into what rheological model best describes viscoplastic behaviour for shear-stresses below the yield-point.
4
Antas, Vilém. "Yield Curve Constructions." Master's thesis, Vysoká škola ekonomická v Praze, 2016. http://www.nusl.cz/ntk/nusl-264627.
Testo completoAbstract (sommario):
The goal of this thesis is to analyze the mathematical apparatus of the most widespread methods used for the yield curves construction. It aims to introduce not only the various of construction models but also to describe the whole process of creation, while discussing the advantages and disadvantage of individual methods. The first chapter focus on the general theory and the use of the term structure of interest rates in practice. The second part deals with the construction process itself and describes the most frequently used methods. The last chapter then shows the real application of selected methods on given data set and the use of the constructed yield curves for interest rate derivative valuation too.
5
Cooney, Mackenzie C. "Yield-Curve Momentum." Scholarship @ Claremont, 2019. https://scholarship.claremont.edu/cmc_theses/2244.
Testo completoAbstract (sommario):
It has been twelve years since the last time the yield curve was inverted. Since 2017, the yield curve has been continuing to flatten and has almost entered an inverted state. The last five recessions have been preceded by the inversion of the yield curve. I examine momentum trading strategy’s ability to outperform during an inverted yield curve state. The yield curve can enter the momentum portfolio strategy through the portfolio’s formation and holding period. I document the increased performance of the momentum strategy’s total portfolio return in an inverted state. These results have implications on the timing a momentum trading strategy might be implemented.
6
Li, Dandan. "SOYBEAN QTL FOR YIELD AND YIELD COMPONENTS ASSOCIATED WITH GLYCINE SOJA ALLELES." UKnowledge, 2006. http://uknowledge.uky.edu/gradschool_diss/331.
Testo completoAbstract (sommario):
USA soybean germplasm has a narrow genetic base that could be augmented by alleles from the wild species Glycine soja which positively influence agronomic traits. The objective of this study was to identify such alleles for yield and yield component QTL (quantitative trait loci). Two populations of 150 BC2F4 lines were generated from a mating between recurrent parent Glycine max 7499 and donor parent Glycine soja PI 245331 with one line in each population tracing back to the same BC2 plant. Population A was used for the QTL identification analysis and population B was used for the QTL verification test. The population A lines were genotyped at 120 SSR marker loci and one phenotype marker, covering a total map length of 1506 cM in 20 linkage groups with an average interval size of 12.5 cM. There were nine putative QTL significantly (Pandlt;0.0001, LODandgt;3.0) associated with yield and yield component traits across 3 environments. One QTL for seed yield was identified using the combined data; the G. soja allele at satt511 on LG-A1 was associated with increased seed yield (LOD=4.3) with an additive yield effect of 190 235 kg ha-1 depending on the QTL analysis method. The phenotypic variance accounted for by the QTL at satt511 was 12%. This QTL also provided a significant yield increase across environments in the validation population; lines that were homozygous for the G. soja allele at satt511 demonstrated a 6.3% (P=0.037) yield increase over lines that were homozygous for the G. max allele. One seed filling period QTL was identified at satt335 (LOD=4.0) on LG-F with an additive effect of +1 day. This QTL also provided a +1 day additive effect (LOD=3.3) on maturity. These results demonstrate the potential of using exotic germplasm to improve soybean yield.
7
Gonçalves, Júlia Alves Roque. "Yield gap explaining factors and solutions to improve yields in a maize farm in Portugal." Master's thesis, ISA, 2019. http://hdl.handle.net/10400.5/21289.
Testo completoAbstract (sommario):
Mestrado em Engenharia Agronómica / Instituto Superior de Agronomia. Universidade de Lisboa<br>Over the decades, it has been found that agricultural intensification, that is, the increase in production per hectare, is substantially urgent and necessary, justified by the observed and expected population increase and the impossibility of agricultural expansion. One of the methods for achieving this goal is the study and investigation of yield gaps, which may be explained by unfavorable soil and climate conditions, or less adequate input management.
Given the socio-economic importance of maize crop in Portugal and the need for case studies that exemplify agricultural intensification methods, this dissertation aims to discover which are the reducing factors that justify the gap between the maximum and actual yields, known as yield gaps, which were analyzed between plots and years, and how large was the yield gap over the 10 years.
Through a database of irrigation appropriations, nitrogen applications, sowing dates and climate data, collected over 10 years and provided by Milho Amarelo company, located in the Santarem region, other variables were calculated, such as degree-day accumulation, cultural evapotranspiration and intercepted radiation. These data were analyzed annually according to the whole cycle and according to different phenological phases (vegetative and reproductive).
Once all variables were obtained and organized, statistical methods of bivariate and multivariate analysis were performed. The magnitude of yield gap was calculated according to the Approach 2 indicated by FAO 41.
The results show that interaction of sowing dates with climatic conditions are in the nature of this deviation, with gap’s magnitude ranging from 5% to 20%, depending on the climatic conditions of the year<br>N/A
8
Mills, Robert William. "Fission product yield evaluation." Thesis, University of Birmingham, 1995. http://etheses.bham.ac.uk//id/eprint/4353/.
Testo completoAbstract (sommario):
A new evaluation has been made of the independent and cumulative yields of fission products for a selection of fissioning systems, including fission of nuclides important for reactor design and operation, and for fuel and waste management. The evaluation, which has been given the reference name UKFY3, used a new database of measurements and is considered complete up to early 1993. This database considerably extends and updates the database used for the previous UKFY2 evaluation. The measurement database was analysed to produce a “best estimate” set of fission product yields. Careful study has been made of experimental uncertainties and discrepancies in the data. As some discrepancies could not be resolved the normalised residual technique was used to down-weight discrepant values. Relative and ratio-of-ratio measurements were included in the analysis by an iterative procedure. The measured data, results of the analysis and discrepancies in the data are shown in extensive tables included as appendices to this thesis. The “best estimates” of fission product yields generated by the analysis were then studied to improve the understanding of the systematics of the yield distribution in mass, charge and isomeric state. Models describing these distributions were investigated and fitted. The effects of the fissioning nucleus mass and charge were examined, as well as the effect of neutron energy on the distributions from neutron-induced fission. The results of these studies were then combined with the “best estimates” to generate complete independent and cumulative yields sets for a list of fissioning systems considered important for applications. This set consists of the neutron-induced fission of 232Th, 233,234,235,236,238U, 237,238Np, 238,239,240,241,242Pu, 241,242m,243Am, and 243,244,245Cm, plus the spontaneous fission of 242,244Cm and 252Cf. These complete yield sets were subsequently adjusted to fit the physical constraints of the fissioning process. The new adjusted library produced by the analysis of the UKFY3 database, provisionally called UKFY3.0 has been produced as a computer file in the ENDF-6 format. The new UKFY3.0 file and the UKFY2 file, which has been revised for use in JEF2.2 during this work, were then tested against integral experimental results for delayed neutron and decay heat production respectively. Finally, results of this work are summarized, remaining problems discussed and areas for future work high-lighted.
9
Abrahams, Michael (Michael G. ). "Estimating yield curve noise." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/118001.
Testo completoAbstract (sommario):
Thesis: S.M. in Management Research, Massachusetts Institute of Technology, Sloan School of Management, 2018.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 27-29).<br>In this paper, I explore methods for estimating noise in the yield curve. I evaluate optimization methods for fitting yield curves using the Nelson-Siegel model where recommendations in the literature remain unclear. I provide open source code on Github including contributions to the QuantLib C++ financial library.<br>by Michael Abrahams.<br>S.M. in Management Research
10
Bilhastre, Ângela Germano. "Fitting the yield curve." Master's thesis, NSBE - UNL, 2009. http://hdl.handle.net/10362/9456.
Testo completoAbstract (sommario):
A Work Project, presented as part of the requirements for the Award of a Masters Degree in Finance from the NOVA – School of Business and Economics<br>This paper is concerned with the fitting of the yield curve in order to achieve a
continuous term structure of interest rates by applying two methods: the cubic
polynomial spline by McCulloch (1975), and the Nelson-Siegel-Svensson (1994).
Subsequently, a trading model is used to make sensitivity analysis decisions on whether
to buy or sell a bond (reach/cheap analysis). Finally, with the purpose of forecasting
future yields, out-of-sample forecasts are calculated for the parameters of the Nelson-Siegel-Svensson.
11
Iebesh, Abdulhamid. "Interpolation of Yield curves." Thesis, Mälardalens högskola, Akademin för utbildning, kultur och kommunikation, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-48968.
Testo completoAbstract (sommario):
In this thesis we survey several interpolation methods that are used to construct the yield curves. We also review the bootstrapping and show that the bootstrap is closely connected to the interpolation in the case of bootstrapping yield curve. The most effort is dedicated, in this thesis, on the monotone convex method and on investigation of the difficulties to get accurate yield curves.
12
Siegfried, Cary Ann. ""Failure to Yield": Essays." Thesis, University of North Texas, 2017. https://digital.library.unt.edu/ark:/67531/metadc1062910/.
Testo completoAbstract (sommario):
Failure to Yield is a collection of creative nonfiction that explores themes of presence and emotional connection and expression. The seven essays, which include three flash essays, explore the themes by reflecting on such topics as marriage, parent-child relationships and addiction. The collection is woven together by the author's relationships with her parents and children and by her experiences growing up in a small town in Iowa.
13
Dobiáš, Vladimír. "Arbitrage-Free Yield Curve." Doctoral thesis, Vysoká škola ekonomická v Praze, 2003. http://www.nusl.cz/ntk/nusl-77145.
Testo completoAbstract (sommario):
We address the issue of market incompleteness in the time dimension. Specifically, we focus on interest rate markets and the yield curve extraction. The lack of information about interest rates manifest itself in a non-invertible linear system. The usual approach to circumvent this problem is by applying various curve fitting methods - both parametric and non-parametric. We argue in favor of a novel method relying on information theory, which reformulates the ill-posed linear algebra problem into a well-posed optimization problem, where the linear pricing equations are used as constraints. Local cross entropy is used to determine the optimal solution among the admissible solutions, while all the input prices reflected in constraints are perfectly matched. Large-scale optimization package called AMPL is used extensively throughout this work to obtain the optimal solution as well as to demonstrate the implementation details.
14
LO, CONTE RICCARDO. "Government Bond Yield Spreads." Doctoral thesis, Università Cattolica del Sacro Cuore, 2009. http://hdl.handle.net/10280/639.
Testo completoAbstract (sommario):
Il presente lavoro raccoglie 4 contributi sul tema dei differenziali sui tassi di interesse esistenti tra i membri dell'unione monetaria europea.<br>I investigate the determinants of sovereign yield spreads in EMU.
15
LO, CONTE RICCARDO. "Government Bond Yield Spreads." Doctoral thesis, Università Cattolica del Sacro Cuore, 2009. http://hdl.handle.net/10280/639.
Testo completoAbstract (sommario):
Il presente lavoro raccoglie 4 contributi sul tema dei differenziali sui tassi di interesse esistenti tra i membri dell'unione monetaria europea.<br>I investigate the determinants of sovereign yield spreads in EMU.
16
Barral, Baron Guillaume. "Investigation and validation of QTL for yield and yield components in winter barley." Thesis, University of Newcastle upon Tyne, 2016. http://hdl.handle.net/10443/3329.
Testo completoAbstract (sommario):
The rapid development of biotechnologies in crop genetics has increased the prospects for more efficient crop improvement. In barley breeding programmes, marker assisted selection (MAS) approaches for quantitative trait loci (QTL) for yield and yield components is still developing as it requires a thorough understanding of the genetic architecture of complex traits. This project reports an investigation of QTL for yield and yield components in two-row winter barley using three QTL mapping experiments. First, a bi-parental mapping population from an elite cross identified 23 genetic factors involved in the control of complex traits, including a strong grain weight QTL on the short arm of chromosome 2H. Second, two genome wide association studies (GWAS) were used to explore the genetic diversity for agronomic traits in European variety panels used in the NUE-CROPS and the AGOUEB projects. The integration of QTL mapping results revealed clustering of significant effects as potential targets for MAS. A major QTL cluster identified on 2H suggests that the centromeric HvCEN candidate gene is strongly involved in controlling the phenology and number of grains per ear in two-row winter barley and has additional pleiotropic effects on several agronomic traits. Some QTL effects were further confirmed by a QTL validation experiment using near isogenic lines (NILs) developed from advanced breeding material alongside the mapping experiments. Most of the QTL clusters involving different yield components showed that allele effects mirrored phenotypic correlations and a few QTL clusters were identified that had unidirectional increasing effects on all traits, such as an important tillering locus on 4HL. The exploitation of comparative genomics with rice revealed that SNP haplotypes could be used for candidate gene discovery at barley QTL clusters. The complexity of the QTL clusters associated with yield and yield components highlight the challenges in identifying relevant targets for marker assisted breeding when accounting for pleiotropic effects of loci controlling phenology and correlated traits. The study provides insights into the genetic architecture of complex traits in small grain cereals and for the implementation of associated QTL in commercial barley breeding activities.
17
Sanhueza, Gonzalez Javier Enrique. "Three essays on global yield curve factors and international linkages across yield curves." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/three-essays-on-global-yield-curve-factors-and-international-linkages-across-yield-curves(6dd58365-6d0d-4928-9908-8fdc924df984).html.
Testo completoAbstract (sommario):
This thesis presents three essays on global yield curve factors and international linkages across yield curves. The essays represent a contribution to our understanding of the effect of globalization on yields, addressing three topics: modeling global and local yield curve factors, modeling global and local yield curve factors in excess bond returns and a joint model of global macroeconomic and yield curve factors. The first essay proposes and develops an empirical model of global and local yield curve factors based on three factors proposed by Nelson and Siegel (1987) dynamized and reinterpreted by Diebold and Li (2006) as level, slope and curvature. The results support the existence of a global yield curve composed of global factors which together with local factors describe the yield curve of the USA, Germany and the UK. Specifically, the global factors explain on average 55% of the variance of yields, and impulse response functions indicate that shocks to global factors are larger and last longer than shocks to local factors. In the second essay, we examine the predictability content of the global and local yield curve factor model to predict excess bond returns one year ahead. We use a rolling window of fifteen years to compare in-sample predictability of our model and two benchmark models: the model proposed by Cochrane and Piazzesi (2005) and the global and local factor model proposed by Dahlquist and Hasseltoft (2011). The results indicate that the global and local yield curve factors from our model predict excess bond returns with an adjusted R² up to 59%. We also find that global factors explain up to 58% of the forecast error variance when predicting excess bond returns. Moreover, our model outperforms both competing models considering the USA, Germany and the UK.The third essay proposes and estimates a joint model of global macroeconomic and yield curve factors, which shows the interaction between global yield curve factors and global macroeconomic factors. Our findings show that the influence of macroeconomic factors on yield curve factors is stronger than the influence of yield curve factors on macroeconomic factors.
18
Zhen, Chen. "Celestial satellite and earthly crop yield: informational content of satellite-based crop yield forecasts." Thesis, Montana State University, 2001. http://etd.lib.montana.edu/etd/2001/zhen/ZhenC2001.pdf.
Testo completoAbstract (sommario):
Since the late 70s, burgeoning efforts have been allocated to study the potential of monitoring crop conditions and forecasting crop yields via remote sensing from the satellite. An overwhelming majority of these studies shows that remote sensing from the satellite express high predictive power in crop forecasting. In this thesis, using satellite images to forecast wheat yield from 1989 to 2000 in six Montana Crop Reporting Districts (CRD), several statistical improvements were achieved over extant crop forecasting models. First, different weights were allowed for satellite images obtained at different points of time, accounting for the likely heterogeneous contributions of various crop phenological stages to the final crop yield. Second, crop acreage information was directly modeled. This, to some extent, alleviates the low-resolution problem of existing satellite imagery. Third, jackknife out-of-sample forecasts were generated to formally measure the well-known instability problem of using satellite imagery in crop forecasting across seasons. In addition, the satellite-based crop yield forecasts were compared with those of the U.S. Department of Agriculture (USDA), whose forecasts were based on traditional methods. It is shown that although meaningful crop forecasts can be generated from the satellite imagery late season, the additional yield information that can be extracted from the satellite tends to be limited. Because in the major wheat producing CRDs, the USDA forecasts are already very accurate and little independent information is observed in the satellite-based forecasts. Results suggest the needs to pinpoint crop phenological stages and to calibrate region-specific crop forecasting model.
19
Alghamdi, Mohammed A. M. "Plant growth regulators effects on vegative growth, yield and yield components in winter wheat." Thesis, University of Reading, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.553077.
Testo completoAbstract (sommario):
Three glasshouse experiments and one field experiment were carried out to investigate the effect of the plant growth regulator on vegetative growth and yield components of reduced height isogenic lines of the wheat (Triticum aestivum L.) cultivar Mercia. The first experiment compared the growth regulator response of seven isogenic lines of Mercia. Subsequent experiments used four lines, (Mercia control, Rhtl Rht2, and Rht8). Two glasshouse experiments examined the responses under well watered and water stress conditions. The third glasshouse experiment examined rates and time of application under well watered conditions, whilst the field experiment had different rates of application. In all experiments growth regulators reduced plant height significantly in all lines. Growth regulator decreased total dry matter and grain yield with greatest reduction generally for the control and Rht8 lines. Rhtl was the least affected. There were few significant effects of growth regulator on gas exchange and chlorophyll fluorescence but the trend was for greater values with growth regulator. In the first glasshouse experiment, a rate of 2.0 1 ha-1 applied just before the third node detectable stage under non water stressed and water stressed conditions gave slight increases in yield of up to 14% except for line Rht10 which increased significantly in non-stressed conditions. In the second glasshouse experiment, a rate of 2.5 1 ha" applied at the start of stem elongation under 30% FC and 100% FC gave reductions in yield up to 16% for the growth regulator and 55% under water stress. In the field experiment, rates of 2.5 and 3.0 1 ha-1 applied at the start of stem elongation gave reductions in yield up to 20% mainly through individual seed weight. In the final glasshouse experiment, rates of 2.5 and 3.0 1 ha-l applied at 6 leaves unfolded and 1st node detectable both reduced grain yield.
20
Sunarlin, Novianti. "Soybean development, yield and yield component responses to shade level and time of shading /." The Ohio State University, 1985. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487260135355056.
Testo completo
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Hartzheim, Paul N. H. "Canada's nascent high-yield market." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0016/MQ49568.pdf.
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Adkin, P. "Yield surfaces in cyclic plasticity." Thesis, Coventry University, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.374221.
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Batchelor, Stephen Norman. "Reaction yield detected magnetic resonance." Thesis, University of Oxford, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334884.
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Zhou, Ning 1970. "Improving line yield at Fab17." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/9214.
Testo completoAbstract (sommario):
Thesis (M.B.A.)--Massachusetts Institute of Technology, Sloan School of Management; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2000.<br>Also available online at the DSpace at MIT website.<br>Includes bibliographical references (leaf 77).<br>Fab 17 was a Digital Equipment Corporation semiconductor manufacturing and development facility. In June of 1998, Intel purchased Fab 17 from Digital. Intel shifted the focus to manufacturing and implemented many Intel operation policies. Intel sold equipment back to Digital and reorganized the manufacturing organization. As a result of Intel's initiatives and increasing demand for Fahl 7 products, Fab 17's profitability was improved. Despite improved profitability, Fab 17 was not meeting line yield performance goals. This thesis examines line yield excursions at Fab 17. Root causes are identified, and recommendations are made. The thesis first analyzes the line-yield loss data at Fahl 7 from a macro perspective. Inexperienced technicians and multitasking are found to be associated with most line yield incidents. The thesis then studies line yield excursions in high leverage functional areas in detail. Two major root causes are identified. First, in the reorganization, many technicians switched to new roles and had to be retrained. The training was rushed. Due to low level of automation, processing wafer at Fab 17 requires experience and proficiency. Fab 17's wafer starts increased in the first two quarters of 1999. Technicians had to rush to process the wafers. This resulted in high stress, which leads to high probability of line yield excursion. The inexperienced technicians are even more prone to line yield excursions under high stress. In addition, Fab 17 lacked a minimum staffing policy. Often an inappropriate number of technicians are present on the manufacturing floor. This necessitates multitasking, which creates higher stress and leads to higher probability of line yield excursions. The thesis recommends operations policies to address these issues and reports the actual implementation and some preliminary results.<br>by Ning Zhou.<br>S.M.<br>M.B.A.
25
Félix, Ana Catarina Ramos. "Contagion in sovereign yield spreads." Master's thesis, Instituto Superior de Economia e Gestão, 2013. http://hdl.handle.net/10400.5/6138.
Testo completoAbstract (sommario):
Mestrado em Economia Monetária e Financeira<br>Since the beginning of the sovereign debt crisis in the Euro Area, the main concern for the European leaders is to prevent against the possible contagion from the distress countries, as Greece, Ireland and Portugal. In our research, we will try to understand if there is a spillover effect from the countries mentioned before and which determinants can be considered as a mechanism of transmission of the sovereign debt crisis. We will perform an econometric analysis in a panel of 13 EU countries (Austria, Belgium, Denmark, Finland, France, Greece, Ireland, Italy, the Netherlands, Portugal, Spain, Sweden and the United Kingdom), covering the period 2000:Q1 to 2013:Q1, and after we analyze each country individually, on the basis of a SUR analysis. We find that the countries with deteriorated macro and fiscal fundamentals are more vulnerable to contagion and are more affected by the international, liquidity and credit risks.
26
Chvojka, Erik, and David Lovén. "Dividend yield strategies in Sweden." Thesis, Uppsala universitet, Företagsekonomiska institutionen, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-354811.
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Brand, Howard James Jarrell. "Towards Autonomous Cotton Yield Monitoring." Thesis, Virginia Tech, 2016. http://hdl.handle.net/10919/72908.
Testo completoAbstract (sommario):
One important parameter of interest in remote sensing to date is yield variability. Proper understanding of yield variability provides insight on the geo-positional dependences of field yields and insight on zone management strategies. Estimating cotton yield and observing cotton yield variability has proven to be a challenging problem due to the complex fruiting behavior of cotton from reactions to environmental conditions. Current methods require expensive sensory equipment on large manned aircrafts and satellites. Other systems, such as cotton yield monitors, are often subject to error due to the collection of dust/trash on photo sensors. This study was aimed towards the development of a miniature unmanned aerial system that utilized a first-person view (FPV) color camera for measuring cotton yield variability. Outcomes of the study led to the development of a method for estimating cotton yield variability from images of experimental cotton plot field taken at harvest time in 2014. These plots were treated with nitrogen fertilizer at five different rates to insure variations in cotton yield across the field. The cotton yield estimates were based on the cotton unit coverage (CUC) observed as the cotton boll image signal density. The cotton boll signals were extracted via their diffusion potential in the image intensity space. This was robust to gradients in illumination caused by cloud coverage as well as fruiting positions in the field. These estimates were provided at a much higher spatial resolution (9.0 cm2) at comparable correlations (R2=0.74) with current expensive systems. This method could prove useful for the development of low cost automated systems for cotton yield estimation as well as yield estimation systems for other crops.<br>Master of Science
28
Dehlbom, Gustaf. "Interpolation of the yield curve." Thesis, Uppsala universitet, Tillämpad matematik och statistik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-423128.
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Harper, John. "Alfalfa Yield and Cutting Interactions." College of Agriculture, University of Arizona (Tucson, AZ), 1985. http://hdl.handle.net/10150/200496.
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Harper, John, and David K. Parsons. "Alfalfa Variety Yield Comparison, Coolidge." College of Agriculture, University of Arizona (Tucson, AZ), 1985. http://hdl.handle.net/10150/200500.
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Morita, Rubens Hossamu. "Emerging markets yield curve dynamics." reponame:Repositório Institucional do FGV, 2007. http://hdl.handle.net/10438/1839.
Testo completoAbstract (sommario):
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Previous issue date: 2007-12-18T00:00:00Z<br>This work extendes Diebold, Li and Yueís (2006) about global yield curve and proposes to extend the study by including emerging countries. The perception of emerging market su§ers ináuence of external factors or global factors, is the main argument of this work. We expect to obtain stylized facts.that obey similar pattern found by those authors. The results indicate the existence of global level and global slope factors. These factors represent an important fraction in the bond yield determination and show a decreasing trend of the global level factor low ináuence of global slope factor in these countries when they are compared with developed countries. Keywords: Kalman Filter, Emerging Markets, Yield Curve, and Bond.
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Kirigwi, Francis M. "Identification of markers associated with grain yield and components of yield under water stress in wheat /." Search for this dissertation online, 2005. http://wwwlib.umi.com/cr/ksu/main.
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Whelan, Helen G. "The effect of crop yield potential on disease yield loss relationships in barley (Hordeum vulgare L.)." Lincoln University, 1992. http://hdl.handle.net/10182/1980.
Testo completoAbstract (sommario):
Proportional loss models commonly used in disease surveys are based on the assumption that per cent yield loss is the same in all crops, regardless of their yield potential. Estimates of regional crop loss may be inaccurate if the relationship between disease and yield loss is affected by crop yield potential. The importance of crop yield potential in disease: yield loss modelling was investigated and models for more accurate regional crop loss estimates were developed, taking crop yield potential into account. Two spring sown barley (cv. Triumph) experiments were conducted in 1987/88 and 1988/89 in Canterbury, New Zealand, to study the effect of crop yield potential on the relationship between disease and yield loss. Crop yield potentials of 323 to 806gDM/m² were generated in seven crops by varying nitrogen and water inputs, sowing date (mid-spring and early-summer) and season. Leaf rust (Puccinia hordei Otth) epidemics of different severity were generated by applying fungicides at different times, frequencies and rates to control the natural epidemics. Disease was measured as per cent disease severity (%DS), green leaf area, radiation interception and near-infrared radiation (NIR) reflectance from crop canopies. Yield was measured as total and grain dry weight. Epidemics were severe in the fully diseased plots from GS 34 and 46 to maturity in the late and early sown crops respectively. Disease reduced grain yield by 50 to 63% in 1987/88 and 24 to 38% in 1988/89 in the fully diseased plots. Disease: yield loss models were derived by regression analysis for each crop in 1987/88. Single point, multiple point and area under curve models were derived from %DS and GLAI variables, and proportional (%) and actual (gDM/m²) grain yield. The effect of yield potential was determined by comparing regression equation coefficients for each crop with crop yield potential. An area under green leaf area index curve (AUGLAIC): actual yield model was best suited to determining the effect of yield potential on yield loss. This model was selected because AUGLAIC summarised the effect of disease on plant growth over the season and actual yield represented the crop yield potential in the absence of disease and the response of actual yield to disease. Crop yield potential did not affect actual yield loss caused by leaf rust. Disease measured as AUGLAIC explained most of the variation in yield (R²adj=0.93) for all crops in both years. Assessment of GLAI is not suitable for estimation of regional crop loss because of the requirement for a rapid and low cost method. Reflectance of NIR from the crop canopy was investigated as an alternative to GLAI measurements. Reflectance was correlated significantly (P<0.001) with GLAI (r=0.66 to 0.89) and green area index (r=0.76 to 0.92). Reflectance measured at grain-filling (GS 85-87) explained most (R²adj=0.94) of the variation in yield for all crops in both years. The relationship between AUGLAIC and yield was validated with data from independent diseased and healthy barley crops. The AUGLAIC: yield model described the effects of disease on yield accurately but overestimated yield by 49 to 108% in the healthy crops. Models based on accumulated PAR (photosynthetically active radiation) intercepted by green leaves explained the observed deviations in yield of these crops from the AUGLAIC: yield model. Accumulated PAR models accounted for differences in incident radiation, canopy structure, radiation interception by green leaves, radiation use efficiency and harvest index which are important in determining dry matter production and grain yield. Accumulated PAR models described the effects of disease on crop growth which were not represented by GLAI alone. Variation in crop yield potential at the regional scale is important in disease: yield loss modelling and can be accounted for by using either separate equations for each yield potential crop or crop category, robust models, inclusion of a form function for yield potential or choice of disease and yield variables which integrate yield potential.
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Tarhuni, Abdalla Mohamed. "The potential for improved yield and yield stability in faba bean (Vicia faba L.) cultivar mixtures." Thesis, University of Liverpool, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235564.
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Pidaran, Kalaiyarasi. "Effect of planting geometry, hybrid maturity, and population density on yield and yield components in sorghum." Thesis, Kansas State University, 2012. http://hdl.handle.net/2097/15074.
Testo completoAbstract (sommario):
Master of Science<br>Department of Agronomy<br>Rob M. Aiken<br>Mary Beth Kirkham<br>Prior studies indicate clumped planting can increase grain sorghum yield up to 45% under water deficit conditions by reducing tiller number, increasing radiation use efficiency, and preserving soil water for grain fill. The objective of this study was to evaluate effects of planting geometry on sorghum grain yield. The field study was conducted in seven environments with two sorghum hybrids, four populations, and two planting geometries. Crop responses included leaf area index, yield, and components of yield. Delayed planting decreased yield by 39%, and a later maturing hybrid increased yield, relative to an early hybrid, by 11% under water sufficiency. Clumped planting increased the fraction of fertile culms (culms which formed panicles) from 5-14%. It reduced the number of culms m-2 by 12% under water limiting conditions (at one of two locations) but increased culms m-2 16% under water sufficiency. Seeds per panicle and seed weight generally compensated for differences in panicles m-2, which were related to different planting population densities.
Although agronomic characteristics of hybrids varying in maturity have been widely studied, little information exists concerning their physiological differences. Therefore, the objective of the greenhouse study was to determine if stomatal resistance, leaf temperature, and leaf chlorophyll content differed between two DeKalb grain sorghum [Sorghum bicolor (L.) Moench] hybrids. They were DKS 36-16 and DKS 44-20, of medium-early and medium maturity, respectively, when grown under field conditions in Kansas. Seeds were planted in a greenhouse. Stomatal resistance and leaf temperature were measured 55 days after planting with a Decagon Devices (Pullman, WA) diffusion porometer, and chlorophyll content was measured 119 days after planting with a Konica Minolta (Osaka, Japan) SPAD chlorophyll meter. The two hybrids did not differ in stomatal resistance, leaf temperature, chlorophyll content, height, and dry weight. Their difference in maturity was not evident under the greenhouse conditions. Future work needs to show if hybrids of different maturities vary in physiological characteristics
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Liu, Xiaojun. "Effects of Biosolids Application and Harvest Frequency on Switchgrass Yield, Feedstock Quality, and Theoretical Ethanol Yield." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/19267.
Testo completoAbstract (sommario):
Switchgrass (Panicum virgatum L.) is a promising bioenergy crop for biofuel production. However, the effects of biosolids application on biomass yield, nitrogen (N) concentration, feedstock quality and theoretical ethanol yield (TEY) are rarely reported in the literature. The objectives of this research were: 1) to compare the effects of biosolids application on biomass yield, N concentration, feedstock quality and TEY, and 2) to compare the effects of harvest frequency on biomass yield, N concentration, feedstock quality and TEY. This experiment began in 2010 and tested four plant available N (PAN) rates of biosolids (0, 153, 306, 459 kg ha-1), one urea rate (180 kg ha-1), and two harvest frequencies (cut once in November or cut in July and November) on a Davidson soil at Orange, VA. Biosolids and urea applications increased biomass yield and TEY across years relative to control, but had no effects on measures of feedstock quality. Inconsistent biomass yield responses to harvest frequency were observed during three years. Cutting once per year consistently increased biomass lignin, cellulose, and hemicellulose concentrations, theoretical ethanol potential (TEP), and reduced N and ash concentrations compared to two cuts. Across years one cut increased TEY by 11% over the two cuts. The results demonstrate that biosolids can be applied as an N source to increase biomass yield and TEY. Two cuts increased biomass yield but reduced TEP, and had inconsistent effects on TEY.<br>Master of Science
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Raymond, Fred Douglas. "Reducing Corn Yield Variability and Enhancing Yield Increases Through the Use of Corn-Specific Growth Models." Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/36304.
Testo completoAbstract (sommario):
Crop simulation models (CSMs) are used to evaluate management and environmental scenarios on crop growth and yields. Two corn (Zea Mays L.) crop growth simulation models, Hybrid-Maize, and CERES-Maize were calibrated and validated under Virginia conditions with the goal of better understanding corn response to variable environmental conditions and decreasing temporal yield variation. Calibration data were generated from small plot studies conducted at five site-years. Main plots were plant density (4.9, 6.2, 7.4, and 8.6 plants m-2); subplots were hybrids of differing relative maturity (RM) [early = Pioneer® Brand â 34B97â (108 day RM); medium = Pioneer® Brand â 33M54â (114 day RM); and late = Pioneer® Brand â 31G66â (118 day RM)]. Model validation was generated from large scale, replicated strip plot trials conducted at various locations across Virginia in 2005 and 2006. Prior to model adjustments based on calibration data, both CSMs under predicted corn grain yield in calibration and validation studies. CERES-Maize grain yield prediction error was consistent across the range of tested plant density while accuracy of Hybrid-Maize varied with plant density. Hybrid-Maize-estimated biomass production was highly accurate. Greater leaf area index (LAI) and biomass production were measured than was predicted by the CERES-Maize CSM. Both CSMs were modified based on calibration data sets and validated. Validation results of the calibrated CSMs showed improved accuracy in simulating planting date and environmental effects on a range of corn hybrids grown throughout Virginia over two years. We expect that both modified models can be used for strategic research and management decisions in mid-Atlantic corn production.<br>Master of Science
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Xie, Quan. "Physiological and genetic determination of yield and yield components in a bread wheat × spelt mapping population." Thesis, University of Nottingham, 2015. http://eprints.nottingham.ac.uk/28998/.
Testo completoAbstract (sommario):
A substantial increase in wheat yield is needed for global food security. This requires a comprehensive understanding of the physiological and genetic basis of yield determination. The present study aimed to dissect yield physiologically and genetically in a recombinant inbred line mapping population derived from bread wheat × spelt. A total of 201 traits were investigated in the field and glasshouse across three years, and these traits formed five themes: genetic variation in yield and yield components, and the usefulness of spelt as a genetic resource; tillering dynamics; biomass accumulation; flowering time and subsequent leaf senescence; and grain filling processes. Large genetic variation in all traits was found, and spelt showed many desirable traits and alleles independent of low threshability, so it can be used to broaden genetic diversity for yield improvement in bread wheat, while maintaining the free-threshing habit. Quantitative trait loci for tiller production and survival were identified, which were also affected by light environment under the canopy: low red:far red ratio (R:FR) led to early tillering cessation, few total shoots, high infertile shoot number and shoot abortion, probably resulting from an assimilate shortage due to early and enhanced stem growth induced by low R:FR. More fertile tillers normally contributed to plant yield and grain number, but reduced individual grain weight, partly because of smaller carpels and fewer stem water soluble carbohydrates at anthesis. In addition, preanthesis biomass accumulation increased yield and yield components. For grain weight, slightly early anthesis and delayed but fast leaf senescence were associated with larger grains. Carpel size at anthesis, grain dry matter and water accumulation, as well as grain morphological expansion, determined final grain weight, because of pleiotropy or tight gene linkages. These findings provide deeper insight into yield determination in wheat, and facilitate trait-based physiological and molecular breeding.
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Khomo, Melvin Muzi. "The yield curve as a forecasting tool : does the yield spread predict recessions in South Africa?" Thesis, Rhodes University, 2006. http://hdl.handle.net/10962/d1004722.
Testo completoAbstract (sommario):
This paper examines the ability of the yield curve to predict recessions in South Africa, and compares its predictive power with other commonly used variables that include the growth rate in real money supply, changes in stock prices and the index of leading economic indicators. The study also makes an attempt to find out if monetary policy explains the yield spread's predictive power with regards to future economic activity. Regarding methodology, the standard probit model proposed by Estrella and Mishkin (1996) that directly estimates the probability of the economy going into recession is used. Results from this model are compared with a modified probit model suggested by Dueker (1997) that includes a lagged dependent variable. Results presented in the paper provide further evidence that the yield curve, as represented by the yield spread between 3-month and IO-year government paper, can be used to estimate the likelihood of recessions in South Africa. The yield spread can produce recession forecasts up to 18 months, although it's best predictive power is seen at two quarters. Results from the standard probit model and the modified pro bit model with a lagged dependent variable are somewhat similar, although the latter model improves forecasts at shorter horizons up to 3 months. Compared with other indicators, real M3 growth is a noisy indicator and does not provide much information about future recessions, whilst movements in the All-Share index can provide information for up to 12 months but does not do better than the yield curve. The index of leading economic indicators outperforms the yield spread in the short run up to 4 months but the spread performs better at longer horizons. Based on the results from the study, it appears that changes in monetary policy explain the yield spread's predictive power. This is because the yield spread loses its explanatory power when combined with a variable representing the monetary policy stance of the central bank.
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Martinez, Ascanio Ana Karine <1979>. "Fine Mapping of qroot-yield-1.06, a QTL for Root, Plant Vigor and Yield in Maize." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amsdottorato.unibo.it/7160/1/Martinez_Ascanio_Ana_Karine_Tesi.pdf.
Testo completoAbstract (sommario):
Root-yield-1.06 is a major QTL affecting root system architecture (RSA) and other agronomic traits in maize. The effect of this QTL has been evaluated with the development of near isogenic lines (NILs) differing at the QTL position. The objective of this study was to fine map qroot-yield-1.06 by marker-assisted searching for chromosome recombinants in the QTL interval and concurrent root phenotyping in both controlled and field conditions, through successive generations. Complementary approaches such as QTL meta-analysis and RNA-seq were deployed in order to help prioritizing candidate genes within the QTL target region. Using a selected group of genotypes, field based root analysis by ‘shovelomics’ enabled to accurately collect RSA information of adult maize plants. Shovelomics combined with software-assisted root imaging analysis proved to be an informative and relatively highly automated phenotyping protocol. A QTL interval mapping was conducted using a segregating population at the seedling stage grown in controlled environment. Results enabled to narrow down the QTL interval and to identify new polymorphic markers for MAS in field experiments. A collection of homozygous recombinant NILs was developed by screening segregating populations with markers flanking qroot-yield-1.06. A first set of lines from this collection was phenotyped based on the adapted shovelomics protocol. QTL analysis based on these data highlighted an interval of 1.3 Mb as completely linked with the target QTL but, a larger safer interval of 4.1 Mb was selected for further investigations. QTL meta-analysis allows to synthetize information on root QTLs and two mQTLs were identified in the qroot-yield-1.06 interval. Trascriptomics analysis based on RNA-seq data of the two contrasting QTL-NILs, confirmed alternative haplotypes at chromosome bin 1.06. qroot-yield-1.06 has now been delimited to a 4.1-Mb interval, and thanks to the availability of additional untested homozygous recombinant NILs, the potentially achievable mapping resolution at qroot-yield-1.06 is c. 50 kb.
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Martinez, Ascanio Ana Karine <1979>. "Fine Mapping of qroot-yield-1.06, a QTL for Root, Plant Vigor and Yield in Maize." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amsdottorato.unibo.it/7160/.
Testo completoAbstract (sommario):
Root-yield-1.06 is a major QTL affecting root system architecture (RSA) and other agronomic traits in maize. The effect of this QTL has been evaluated with the development of near isogenic lines (NILs) differing at the QTL position. The objective of this study was to fine map qroot-yield-1.06 by marker-assisted searching for chromosome recombinants in the QTL interval and concurrent root phenotyping in both controlled and field conditions, through successive generations. Complementary approaches such as QTL meta-analysis and RNA-seq were deployed in order to help prioritizing candidate genes within the QTL target region. Using a selected group of genotypes, field based root analysis by ‘shovelomics’ enabled to accurately collect RSA information of adult maize plants. Shovelomics combined with software-assisted root imaging analysis proved to be an informative and relatively highly automated phenotyping protocol. A QTL interval mapping was conducted using a segregating population at the seedling stage grown in controlled environment. Results enabled to narrow down the QTL interval and to identify new polymorphic markers for MAS in field experiments. A collection of homozygous recombinant NILs was developed by screening segregating populations with markers flanking qroot-yield-1.06. A first set of lines from this collection was phenotyped based on the adapted shovelomics protocol. QTL analysis based on these data highlighted an interval of 1.3 Mb as completely linked with the target QTL but, a larger safer interval of 4.1 Mb was selected for further investigations. QTL meta-analysis allows to synthetize information on root QTLs and two mQTLs were identified in the qroot-yield-1.06 interval. Trascriptomics analysis based on RNA-seq data of the two contrasting QTL-NILs, confirmed alternative haplotypes at chromosome bin 1.06. qroot-yield-1.06 has now been delimited to a 4.1-Mb interval, and thanks to the availability of additional untested homozygous recombinant NILs, the potentially achievable mapping resolution at qroot-yield-1.06 is c. 50 kb.
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Maleka, Koena Gideon. "Determination of yield and yield components of selected tomato varities in soil with different levels of cattle manure application." Thesis, University of Limpopo (Turfloop Campus), 2012. http://hdl.handle.net/10386/834.
Testo completoAbstract (sommario):
Thesis (M.Sc. (Crop Science)) --University of Limpopo, 2012<br>Organic tomatoes are increasingly popular with larger market acceptance since organic farming uses limited or no artificial chemicals. Application of organic fertilisers such as cattle manure has potential to boost organic tomato productivity particularly under low input farming systems. However, information is required on the optimum level of manure application on different tomato cultivars to help emerging tomato farmers in South Africa. The objective of this study was to determine the relative response of yield and yield components among selected determinate and indeterminate tomato cultivars using different levels of cattle manure. Two separate field experiments were conducted at the University of Limpopo during 2007 and 2008 using a split plot design with three replications. Two sets of tomato cultivars were included in which one set consisted indeterminate types (Money Maker, Ox Heart and Sweetie) and the other determinates (Roma and Floradade). Cultivars were assigned as the main plot treatments with six rates of manure (0, 10, 20, 30, 40 and 50 in gram per plant) applied as the subplot treatments to each set. Results indicated significant interactions (P ≤ 0.01) between indeterminate tomato cultivars and levels of manure applied for fruit yield and fruit size in both experiments. Plant height showed variation from 78 to168 cm in Experiment I and 87 to 176 cm in Experiment II. During Experiment I fruit number varied from 23 to 91 per plant and 23 to 97 in Experiment II. Significant differences were detected among determinate cultivars on fruit yield varying from 7928 to 3 4705 kg per hectare during Experiment I and 3 169 to 2 9840 kg per hectare during Experiment II. Overall, the best level of manure for maximum fruit yield and greater fruit size was achieved at 40 g per plant in the indeterminate cultivar Sweetie. Conversely, the best level of manure for maximum fruit yield was achieved at 30 g per plant in determinate cultivar Roma. Thus, to achieve maximum yield, tomato growers could apply 600 and 800 kg per hectare manure on the determinate and indeterminate tomato cultivars, respectively.<br>the National Research Foundation (NRF)
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Wilson, Laurie L. "Yield stress studies on molten chocolate." Thesis, University of British Columbia, 1991. http://hdl.handle.net/2429/29792.
Testo completoAbstract (sommario):
A study of the flow properties of four chocolate samples was conducted. These were commercial semi-sweet (HSS), milk chocolate (HMC) and two experimental samples (H1 and H2). The yield stress, an important quality indicator of the chocolate, was estimated from steady shearing flow data by extrapolating the Casson model equation to zero flow rate and, by allowing stresses to relax after shearing. As well, undisturbed samples were examined in start-up flow using Single Vane and Multiple Vane methods. Proximate and sucrose analyses were carried out to determine the chemical composition of each chocolate sample. The mean particle size and the distribution of sizes contained in the samples was determined to further characterize the chocolates.
A multivariate analysis of variance indicated that there was a significant difference in chemical composition among the four test samples. The mean particle sizes ranged from 5.73 to 6.27, 6.98 and 7.15 µm for samples HSS, H1, HMC and H2, respectively. The greatest number of particles were in the size range of 4.0 to 5.0 µm.
The Casson model equation was fitted to steady flow data obtained with coaxial cylinder fixtures using a Brookfield HAT viscometer, a Brabender Rheotron viscometer, and a Carri-Med Controlled Stress Rheometer. For the Brookfield viscometer, the Casson
equation over the shear rate range used, was found to accurately describe the flow characteristics of chocolate samples HMC, HSS and H2, but not sample H1.
For the Brabender viscometer and the Carri-Med rheometer, the Casson equation did not fit the flow data over the entire shear rate range used with each instrument. A deviation in linearity occurred below approximately 0.5 s‾1 in the flow data measured in both instruments, thereby making the yield stress determination somewhat ambiguous.
Yield values recalculated using only the linear data points were higher. In addition, for the Brabender viscometer, significant differences (p<0.05) were observed in both the yield and viscosity values measured using two coaxial cylinder fixtures of different annular gap widths. Using the Carri-Med rheometer, a significant difference in viscosity (p<0.05) over consecutive test runs was found and a significant difference (p<0.01) in yield stress when samples were sheared for 12 minutes as compared to 30 minutes.
Yield stress estimates obtained using Multiple Vane Method I and Method II were comparable for chocolate samples HMC, HSS, and H2, but were significantly higher for sample H1 when using Method II as compared to Method I. Method II may be a more accurate estimate of the yield value of molten chocolate because the assumption of a uniform shear stress distribution over the ends of the vane fixture could not be proven experimentally for samples HSS and H1 when using Method I. Also, the dependence of the yield value on the rotational speed was evident when the vane data were analyzed using Method I, but was not a significant factor (p>0.05) when Method II was used to estimate yield stress. In addition, the single point measurements used to estimate yield stress agreed more closely with values obtained using Method II as compared to Method I.
It is postulated that the Single Vane Method or Multiple Vane Method II may provide more accurate estimates of the yield stress of molten chocolate than using the Casson approximation. For the vane methods, direct measurements were taken under virtually static conditions; whereas, in the Casson extrapolation method, yield stress was estimated indirectly from flow data over a broad shear rate range at stresses well beyond the yield point of the sample. The Single Vane Method was simple and required less time than fitting the Casson flow model to shear stress-shear rate data and, therefore, may be more suitable for routine yield stress measurements of molten chocolate in quality control laboratories.<br>Land and Food Systems, Faculty of<br>Graduate
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Zaabab, Abdel Hafid. "SCFL VLSI circuits for improved yield." Thesis, University of Ottawa (Canada), 1993. http://hdl.handle.net/10393/6599.
Testo completoAbstract (sommario):
In this thesis an improvement to the Gallium Arsenide source coupled FET logic ECL output cell is presented. Because of parameter variations from site-to-site in the wafer, ECL compatibility of source coupled FET logic circuits, in terms of voltage levels and clock duty cycle, was very poor and therefore the electrical yield was very low. A source coupled FET logic buffer driver was designed to make the Gallium Arsenide ECL cell more resistant to parameter variations and consequently, the yield is highly improved. Furthermore, multi-site circuits are now possible with a high output electrical yield. The circuit complexity is limited by the latency problem which occurs when using both high and low frequency signals to drive the gate. In this research, the latency time period is reduced by over 75% and hence either the operating frequency or the complexity can be increased six times.
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De, Bruin Jason Lee. "Maximizing soybean yield potential in Iowa." [Ames, Iowa : Iowa State University], 2007.
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Njoroge, Kiarie. "Earliness and yield in Katumani maize." Thesis, University of Cambridge, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305695.
Testo completo
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Ibrahim, Yahuza. "Extending yield/density equations for intercropping." Thesis, University of Reading, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.553122.
Testo completoAbstract (sommario):
Five experiments agronomically managed differently investigated yield/density relationships in wheat/faba bean (bean) intercrop system. Mostly wheat seed yields (SY) responses were asymptotic to increase in wheat seed rate (wsr). For the wheat sole crop (WSC), SY ranged from 102 g/m2-734 g/m2. Intercropping reduced wheat SY but this did not always depend on wsr. The maximum bean sole crop SY was 392g/m2: bean SY declined as wsr increased. In most cases biomass yield (BY) responses followed similar pattern as the SY. The total intercrops (TI) SY were greater than the sole crops (SC) mostly where wheat intercrop BY were not substantially reduced. Also, mostly the TI accumulated more photosynthetically active radiation (PAR) whilst WSC was better at radiation use efficiency (RUE) as wsr increased. Intercrop performance (IP) were assessed from results and fitted values (FV) after yield/density equations (YDE) were applied (for the SY) using land equivalent ratio (LER), crop performance ratio (CPR) and another index. For the SY, a maximum LER of 2.20, and a maximum CPR of 1.61 were obtained. In two experiments LER > 1.0 but CPR < 1.0 were obtained, indicating that the TI were less efficient than Se. Estimates of IP using FV, did not consistently agreed with estimates of IP using results. In one experiment, sulphur application increased bean but reduced wheat SY. The effects of sulphur on SY were mainly determined by the BY and the PAR. In another experiment, delaying bean sowing reduced bean and increased wheat SY. Effects of different bean sowing dates on SY were determined by variables similar to the effect of sulphur above. Moreover, across the experiments, wsr and intercropping reduced weed biomass substantially, and weeds biomass inclusions had effects on the estimate of RUE. In conclusion, wheat/bean intercrop system is beneficial, and YDE can quantify the intercrop yields well.
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Marakbi, Zakaria, and VYDRIN CARLOS JUNIOR LOPEZ. "High Yield Corporate Bond Portfolio Optimization." Thesis, KTH, Optimeringslära och systemteori, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-146746.
Testo completoAbstract (sommario):
The fixed maturity, cash flow and risk characteristics of high-yield corporate bonds distinguish them from equities and complicate a direct application of well established optimization techniques such as Markowitz's mean-variance model and Sharpe ratio maximization. This can partly explain why qualitative methods constitute the dominant design in the portfolio selection process of high-yield corporate bonds. This thesis attempts to employ elements from Markowitz's theories and combine them with optimization- as well as financial theory in order to develop a quantitative optimization model. In addition, we examine the possibilities for a shift in the existing dominant design. A risk-neutral pricing model were used to estimate default probabilities of high yield corporate bonds. To approximate the covariance matrix, a new application of the single-index method were proposed. The derived optimization models produced results that coincide with financial theory regarding risk, return and diversification. Furthermore, an examination of a potential shift in the current dominant design suggests that a shift is not likely to occur in the near future. A reoccurring remark in this thesis is the importance to understand the underlying assumptions behind any quantitative model, suggesting that quantitative models can merely be used as a tool in combination with a human judgement.<br>Högavkastande företagsobligationer innehar egenskaper som särskiljer de från aktier. Detta medför komplikationer vid en direkt tillämpning av väletablerade optimeringsmodeller som 'Markowitz's mean-variance model' och 'Sharpe ratio maximisation'. Detta förklarar delvis varför kvalitativa metoder dominerar portföljallokeringsprocessen för högavkastande företagsobligationer. Examensarbetet kombinerar Markowitzs modell med teorier från optimeringslära och finansiell matematik i syfte att utveckla en kvantitativ optimeringsmodell för portföljallokering. Arbetet ämnar även till att undersöka möjligheterna för ett skift i den nuvarande dominanta processen för allokering av högavkastande företagsobligationer. En riskneutral prissättningsmodell tillämpades för att estimera sannolikheter att företagen går i konkurs. För att approximera kovariansmatrisen introduceras en ny tillämpning av 'single-index method'. De härledda optimeringsmodellerna visade på resultat som sammanfaller med finansiell teori angående risk, avkastning och diversifiering. En analys av möjligheterna för ett potentiellt skift i den dominerande processen påvisade att detta förmodligen ej kommer att ske inom en snar framtid. En återkommande anmärkning i detta examensarbete ar vikten av modellmedvetenhet och att således ha kunskap om de underliggande antaganden som modellen bygger på, vilket framgår av slutsatsen att kvantitativa metoderna enbart kan användas som ett verktyg och därav agera som ett underlag för beslutsfattande.
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Gafga, Philip Henry. "The information in the yield curve." Thesis, Durham University, 1995. http://etheses.dur.ac.uk/5432/.
Testo completoAbstract (sommario):
The term structure of interest rates as described by yield curves has the potential to contain information about the course of future nominal and real interest rates, inflation and economic activity. The link between the yield curve and these economic variables is formalised via capital asset pricing models. The information in yield curves is examined in a systematic manner using two new term structure data sets. The first one is an extended version of the McCulloch yield data for the United States for the period 1947-91 and the second one is a new highly detailed data set for the United Kingdom supplied by the Bank of England for this study, which consists of daily observations on yields for the period 4th January 1983 to 30th November 1993.Empirical evidence for the United States for the period 1952-91 shows that inflation and real interest rate changes tend to offset each other so that there is no useful information about nominal interest rates. Information about the real term structure is sometimes obscured by the offsetting effects of real interest rates and term premiums. Evidence is presented that shows yield spreads may give more unambiguous signals about economic activity if such activity is measured in relative terms. The better predictive power of UK term structures with regard to nominal interest rates is due to inflation and real interest rates moving together in the same direction. The phenomenon of disinflation can produce highly significant information about the real term structure. For the US and, more particularly, the UK, the predictive power of the yield curve is subject to significant change. The main conclusion reached is that over-reliance certainly should not be placed on the yield curve as a leading economic indicator.
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Maragos, Spyridon A. (Spyriodon Apostolos). "Yield management for the maritime industry." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/12031.
Testo completo