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  • 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.
1

Effects of mix uniformity in diets with high inclusion of alternative ingredients on growth performance and carcass characteristics in swine and poultry

Morts, Megan January 1900 (has links)
Master of Science / Department of Animal Sciences and Industry / Joe D. Hancock / Three finishing pig and one broiler chick experiment were completed to determine the effect of diet formulation, mix time, and diet form on growth performance and carcass measurements. In Exp. 1, finishing pigs fed corn-soy diets had greater ADG, HCW, DP, and BF (P < 0.05) compared to pigs fed diets with 30% DDGS and 10% wheat middlings. However, increasing mix time from 60 to 420 s did not affect growth performance or carcass measurements (P > 0.38). In Exp. 2, pigs were fed diets with 32% DDGS and 32% wheat middlings and were mix for 0, 15, 30, 60, or 420 s. There were no differences in growth performance or carcass measurements as mix time was increased from 0 to 420 s (P > 0.06). In Exp. 3, pigs were fed 32% DDGS and 32% wheat middlings in meal and pelleted diets that were mixed for 0 or 180 s. Pelleting diets increased ADG and improved G/F (P > 0.01). Increasing mix time had no effect on ADG or G/F (P > 0.16) as mix time was increased from 0 to 180 s. There were no differences in carcass measurements because of diet form or mix time. In the final experiment (Exp. 4), broiler chicks were fed a corn-soy diet or a diet with 20% DDGS and 20% wheat middlings and mixed for 0, 15, 30, 60, and 300 s. Broiler chicks fed the corn-soy diet had greater G/F (P < 0.01) but increasing mix time from 0 to 300 s did not affect growth performance or carcass characteristics (P > 0.13). Increased mix time in diets with high levels of alternative ingredients does not affect growth performance or carcass measurements when fed to finishing pigs or broiler chicks.
2

Analysis of multilayer coatings by electron microscopy

Davock, Helen Jane January 1998 (has links)
No description available.
3

The Uniformity Space of Hypergraphs

Mol, Lucas 13 August 2012 (has links)
For a hypergraph H=(V,E) and a field F, a weighting of H is a map f:V ?F. A weighting is called stable if there is some k ? F such that the sum of the weights on each edge of H is equal to k. The set of all stable weightings of H forms a vector space over F. This vector space is termed the uniformity space of H over F, denoted U(H,F), and its dimension is called the uniformity dimension of H over F. This thesis is concerned with several problems relating to the uniformity space of hypergraphs. For several families of hypergraphs, simple ways of computing their uniformity dimension are found. Also, the uniformity dimension of random l-uniform hypergraphs is investigated. The stable weightings of the spanning trees of a graph are determined, and lastly, a notion of critical uniformity dimension is introduced and explored.
4

Characterization of wastewater subsurface drip emitters and design approaches concerning system application uniformity

Duan, Xiaojing 02 June 2009 (has links)
Subsurface drip distribution is an important on-site wastewater treatment technique which is widely used with various soil types and restricted site conditions. It can distribute pretreated wastewater uniformly into soil. Some recent field applications showed low application uniformities, which was reflected in overloading of the field near the supply manifold while low emitter discharge rates occurred at the end of lateral. Designers are seeking appropriate operation pressures and drip zone configurations to improve system application uniformity. This research was conducted to test some popular wastewater drip products in both lab and field-scale experiments. The first goal of this study was to evaluate the performance of five subsurface drip products under eight operational pressures ranging from 0 to 310 kPa (45 psi). After evaluation of each group of 60 emitters, results showed that Netafim Bioline pressure compensating (PC) emitters exhibited a uniformity coefficient (UC) of 95% with a coefficient of variance (Cv) of 4.9%. The average UC of Geoflow Wasteflow products is 94.4% and Cv value is 6.8%. Flow rate and pressure relationships (Q-H curves) were developed for each drip emitter tested. By analyzing low and normal operational pressure ranges, Q-H curves were fitted to the data and resulted in R2 values ranging from 1.000 to 0.414. Geoflow pressure compensating products possess the features of non-pressure compensating emitters under low pressure head. Netafim PC products are characterized as pressure compensating over the full range of operational pressures and emit water with nominal uniformity during low pressure range. To evaluate drip zone configurations with respect to distribution uniformity, a field-scale experiment was set up and three drip tubing products were tested in different dosing and operation schemes. Three factors of wastewater drip system design were tested. System operation pressure (138 kPa/20 psi and 276 kPa/40 psi); different pressure control components (pressure regulator/recirculation valve) and schemes (continuous flushing/intermittent flushing); and supply line length (7.6 m/25 ft, 15.2 m/50 ft, and 30.4 m/100 ft) were evaluated to compare their influence on water application uniformity. It was concluded that, for Geoflow PC and NPC products, among all three factors, system operational pressure has the greatest effect on drip system application uniformity; supply line length has the least influence. For Netafim PC tubing, pressure control scheme has the greatest effect on drip system application uniformity; supply line length has the least influence. The optimal combination of the three factors could save more than 10 minutes of dosing time to meet the required dosing application uniformity. An engineering computation example on system fill time was presented and compared to experimental results to demonstrate the possible gap between typical design processes and real field application.
5

Spelar det någon roll vem det är som utför kontrollen? : En studie av enhetlighet avseende bedömning av regelefterlevnad i livsmedelskontroll

Karlsson, Tommy January 2015 (has links)
Legislation on official controls requires competent authorities to carry out a risk-based control in a uniform way. The purpose of this study was to investigate whether data from official controls can be used to examine to what extent the assessment of compliance is performed in a uniform way. Data from official controls carried out by a competent authority were examined for differences in the assessment of non-compliance amongst the control staff. The dissemination of non-compliance within a selection of regulatory requirements was also examined. The result shows that the proportion non-compliances increase when more than one inspector is present. Inspectors carrying out fewer controls show significant differences in their assessment of compliance with certain requirements. Under certain conditions dispersion measures based on the proportion of non-compliances can be used as indicators or comparative figures for consistency.
6

The influence of stress variations in wet pressing

Gullbrand, Jörgen January 2004 (has links)
<p>Two methods for the measurement of micro-scale stressvariations of press felt surfaces were developed. The methodswere based on a thin plastic film that was coated with anopaque stress-sensitive layer (Cronapress conversion film). Thefilm was compressed between a felt and a smooth surface. Uponapplication of load the opaque layer became partiallytransparent at the locations where load was applied by thesurface fibres of the felt. The degree of transparency was afunction of the locally applied stress. The spatial resolutionof the method was 6.3 µm, which means that even details ofthe order of the diameter of a batt fibre diameter can beresolved.</p><p>Parameters characterising the stress variations were used toquantitatively describe the extent of the stress variations,the size of the contact areas and the distance between them.The applicability of these contact characterisation parameterswas evaluated in laboratory wet pressing experiments and inpilot paper machine trials for two sets of specially designedpress felts. In general, the dewatering result was mainlyinfluenced by the diameter of the felt surface batt fibres andby the web grammage. For a specific pulp type and operatingconditions a multivariate model was formulated based on themeasured web dryness, web grammage and each contactcharacterisation parameter. The model was able to describe thedewatering capability of the different felts tested. Contactcharacterisation parameters related to contact properties (e.g.contact area ratio) gave the best prediction for low grammagewebs, while parameters related to flow properties (e.g. size ofopenings) gave the best prediction for high grammage webs.</p><p>Furthermore it was found that at a certain web grammage, thesurface batt fibre diameter did not have an influence on thedewatering result. This grammage was termed "transitiongrammage". Below the transition grammage a fine surface gavesignificantly better dewatering, while the opposite trend wasobserved above the transition grammage. Based on these results,a modified dewatering hypothesis was formulated. Thishypothesis links the non-uniform compression of the wet webwith different dewatering situations for low and high grammagewebs.</p><p><b>Keywords</b>Press felts, Roughness, Smoothness, SurfaceStructure, Uniformity, Wet pressing, Batt fibre, Base weave,Stress variations, Micro-scale.</p>
7

The implications of compartment fire non-uniformity for the membrane action of reinforced concrete slabs

Deeny, Susan January 2011 (has links)
Maintaining structural stability is an integral component of building fire safety. Stability must be ensured to provide adequate time for safe egress of the buildings occupants, fire fighting operations and property protection. Structural fire engineering endeavours to design structures to withstand the effects of fire in order to achieve this objective. The behaviour of reinforced concrete in fire is not as well understood as other construction materials, such as steel. This is in part due to the complexity of concrete material behaviour and also due to concrete’s reputation of superior fire performance. Concrete technology is, however, continually evolving; structures are increasingly slender, more highly stressed and have higher compressive strengths. A more robust understanding of concrete’s behaviour in fire will enable predictions of the implications of changing concrete technology and also help to properly quantify the fire safety risk associated with concrete structures. A fundamental key to understanding structural fire performance is the relationship between the thermal environment induced by the fire and the structure. Significant thermal variation has been found experimentally to exist within fire compartments. Despite this the design of structures for fire almost universally assumes the compartment thermal environment to be homogeneous. In this thesis the implications of compartment fire non-uniformity for concrete structural behaviour is investigated to assess the validity of the uniform compartment temperature assumption. The investigation is conducted using numerical tools; a detailed review of the necessary background knowledge, material modelling of reinforced concrete, finite element modelling of reinforced concrete structures and compartment fire thermal variation is included. The behaviour of a two-way spanning reinforced concrete slab is used as a structural benchmark. The membrane behaviour exhibited by two-way spanning RC slabs at high temperatures has been previously studied under uniform thermal conditions. They therefore are an ideal benchmark for identifying the influence of non-uniform thermal environments for behaviour. The relationship between gas phase temperature variation and concrete thermal expansion behaviour, which is fundamental to understanding concrete high temperature structural behaviour, is first investigated. These preliminary studies provide the necessary fundamental understanding to identify the influence of gas phase temperature variation upon the membrane behaviour of reinforced concrete slabs. The individual influences of spatial and temporal variation upon slab membrane behaviour are investigated and the behaviour under non-uniform thermal variation contrasted with uniform thermal exposure behaviour. The influence of spatial variation of temperature is found to be strongly dependent upon the structural slenderness ratio. The tensile membrane action of slender slabs is particularly susceptible to the distorted slab deflection profiles induced by spatial variation of gas temperature. Conversely the compressive membrane behaviour of stocky slabs is found to be insensitive to the deformation effects induced by spatial variation of temperature. The influence upon slender slabs is demonstrated under a range of temporal variations indicating that the thermal response of concrete is sufficiently fast to be sensitive to realistically varying distributions of temperature. Contrasting behaviour induced by uniform and non-uniform thermal exposures indicates that uniform temperature assumptions provide both conservative and unconservative predictions of behaviour. The accuracy of the uniform temperature assumptions was also found to be dependent upon the type of fire, for example, fast hot and short cool fires. Additionally, the sensitivity of structural performance to deformations caused by spatial variation of temperature demonstrated in this thesis challenges the purely strength based focus of traditional structural fire engineering. Spalling is an important feature of concrete’s high temperature behaviour which is not currently explicitly addressed in design. The incorporation of spalling into structural analysis is not, however, straightforward. The influence of spalling upon behaviour has therefore been dealt with separately. A spalling design framework is developed to incorporate the effects of spalling into a structural analysis. Application of the framework to case studies demonstrates the potential for spalling to critically undermine the structural performance of concrete in fire. It also demonstrates how the framework can be used to quantify the effects of spalling and therefore account for these in the structural fire design addressing spalling risk in a rational manner.
8

Effects of maternal management and nutrition on broiler chicken carcass uniformity

Holm, Deborah 11 1900 (has links)
This project researched the effects of pullet-phase feed restriction methodology or management and hen-phase diet fortification on female broiler breeder BW and carcass trait uniformity as well as on performance of the broiler offspring. Feed treatments had a significant effect on female BW and carcass trait uniformity at 22 wk of age, with sorting and scatter treatments having the highest uniformity estimates, compared to limited daily, skip-a-day and fibre-diluted programs. Feed and premix treatments did not affect traits after 22 wk of age as individual caging at 22 wk of age unified female BW uniformity across all treatments. Feed treatments did not affect the uniformity of age at sexual maturity, first egg characteristics or production parameters. Premix treatment resulted in decreased shell uniformity and increased uniformity of one of the production parameters, total egg mass. Feed treatments may have a greater effect on female broiler breeder efficiency than previously suggested. / Animal Science
9

Design and fabrication of novel microfluidic systems for microsphere generation

Song, Ki-Young 30 May 2011
<p>In this thesis, a study of the rational design and fabrication of microfluidic systems for microsphere generation is presented. The required function of microfluidic systems is to produce microspheres with the following attributes: (i) the microsphere size being around one micron or less, (ii) the size uniformity (in particular coefficient of variation (CV)) being less than 5%, and (iii) the size range being adjustable as widely as possible.</p> <p>Micro-electro-mechanical system (MEMS) technology, largely referring to various micro-fabrication techniques in the context of this thesis, has been applied for decades to develop microfluidic systems that can fulfill the foregoing required function of microsphere generation; however, this goal has yet to be achieved. To change this situation was a motivation of the study presented in this thesis.</p> <p>The philosophy behind this study stands on combining an effective design theory and methodology called Axiomatic Design Theory (ADT) with advanced micro-fabrication techniques for the microfluidic systems development. Both theoretical developments and experimental validations were carried out in this study. Consequently, the study has led to the following conclusions: (i) Existing micro-fluidic systems are coupled designs according to ADT, which is responsible for a limited achievement of the required function; (ii) Existing micro-fabrication techniques, especially for pattern transfer, have difficulty in producing a typical feature of micro-fluidic systems - that is, a large overall size (~ mm) of the device but a small channel size (~nm); and (iii) Contemporary micro-fabrication techniques to the silicon-based microfluidic system may have reached a size limit for microspheres, i.e., ~1 micron.</p> <p>Through this study, the following contributions to the field of the microfluidic system technology have been made: (i) Producing three rational designs of microfluidic systems, device 1 (perforated silicon membrane), device 2 (integration of hydrodynamic flow focusing and crossflow principles), and device 3 (liquid chopper using a piezoelectric actuator), with each having a distinct advantage over the others and together having achieved the requirements, size uniformity (CV ⤠5%) and size controllability (1-186 &#x00B5;m); (ii) Proposing a new pattern transfer technique which combines a photolithography process with a direct writing lithography process (e.g., focused ion beam process); (iii) Proposing a decoupled design principle for micro-fluidic systems, which is effective in improving microfluidic systems for microsphere generation and is likely applicable to microfluidic systems for other applications; and (iv) Developing the mathematical models for the foregoing three devices, which can be used to further optimize the design and the microsphere generation process.</p>
10

Design and fabrication of novel microfluidic systems for microsphere generation

Song, Ki-Young 30 May 2011 (has links)
<p>In this thesis, a study of the rational design and fabrication of microfluidic systems for microsphere generation is presented. The required function of microfluidic systems is to produce microspheres with the following attributes: (i) the microsphere size being around one micron or less, (ii) the size uniformity (in particular coefficient of variation (CV)) being less than 5%, and (iii) the size range being adjustable as widely as possible.</p> <p>Micro-electro-mechanical system (MEMS) technology, largely referring to various micro-fabrication techniques in the context of this thesis, has been applied for decades to develop microfluidic systems that can fulfill the foregoing required function of microsphere generation; however, this goal has yet to be achieved. To change this situation was a motivation of the study presented in this thesis.</p> <p>The philosophy behind this study stands on combining an effective design theory and methodology called Axiomatic Design Theory (ADT) with advanced micro-fabrication techniques for the microfluidic systems development. Both theoretical developments and experimental validations were carried out in this study. Consequently, the study has led to the following conclusions: (i) Existing micro-fluidic systems are coupled designs according to ADT, which is responsible for a limited achievement of the required function; (ii) Existing micro-fabrication techniques, especially for pattern transfer, have difficulty in producing a typical feature of micro-fluidic systems - that is, a large overall size (~ mm) of the device but a small channel size (~nm); and (iii) Contemporary micro-fabrication techniques to the silicon-based microfluidic system may have reached a size limit for microspheres, i.e., ~1 micron.</p> <p>Through this study, the following contributions to the field of the microfluidic system technology have been made: (i) Producing three rational designs of microfluidic systems, device 1 (perforated silicon membrane), device 2 (integration of hydrodynamic flow focusing and crossflow principles), and device 3 (liquid chopper using a piezoelectric actuator), with each having a distinct advantage over the others and together having achieved the requirements, size uniformity (CV ⤠5%) and size controllability (1-186 &#x00B5;m); (ii) Proposing a new pattern transfer technique which combines a photolithography process with a direct writing lithography process (e.g., focused ion beam process); (iii) Proposing a decoupled design principle for micro-fluidic systems, which is effective in improving microfluidic systems for microsphere generation and is likely applicable to microfluidic systems for other applications; and (iv) Developing the mathematical models for the foregoing three devices, which can be used to further optimize the design and the microsphere generation process.</p>

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