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1
Bakhurji, Khalid A. « Cascade control for a steam-heated double-pipe heat exchanger ». Thesis, California State University, Long Beach, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=1596967.
Texte intégralRésumé :
The goal of this thesis is to create the experimental setup and the necessary instrumentation for the temperature control of a double-pipe heat exchanger. The heat exchanger, located at the Chemical Engineering Control Laboratory at the California State University, Long Beach, has been used in the past for temperature control experiments, in which the manipulated variable was the incoming water flow. In the control experiments performed for the current work, the manipulated variable is the incoming steam pressure. For this purpose cascade control has been used, with an inner loop controlling the steam pressure setpoint, and an outer loop controlling the water outlet temperature. Despite major fluctuations in the steam pressure supply and inappropriate sizing of a control valve, the experimental results show that the designed cascade control can track the temperature setpoint and reject load-induced disturbances satisfactorily. System parameters are obtained via experimental modeling through open loop experiments. A LabView-based data acquisition and control program has been written and implemented for acquiring and processing sensor outputs, and for providing control commands to the final control elements. Several controller parameter tuning methods, such as IMC, ITAE, Cohen-Coon, and Ziegler-Nichols, were implemented and evaluated experimentally through a set of performance indices.
2
Pieters, Alfred Cornelius. « Whip restraint for a steam pipe rupture event on a nuclear power plant / Alfred Cornelius Pieters ». Thesis, North-West University, 2013. http://hdl.handle.net/10394/9391.
Texte intégralRésumé :
One of the requirements of a safe nuclear power plant design is the postulation of the
dynamic effects of a steam pipe rupture. The dynamic effects are the discharging fluid and
pipe whip on structures, systems or components. A pipe rupture can be caused in the steam
pipe system where a defect such as a crack exists.
Multiple factors contribute to the initiation of pipe cracks during the plant’s life. Cracks may
start microscopically small and over time, with the assistance of cyclic operation, fatigue may
elongate the crack. When a steam pipe is cooled by water during an accident, steam
condensate may accumulate and form slugs of water. This water will have an effect on the
system termed condensation induced water hammer. The cause of the pipe rupture is not
addressed in this dissertation.
Pipe rupture can be considered to be either a circumferential or longitudinal break. For the
purpose of this dissertation only a circumferential break will be considered.
This research is based on the development of a pipe whip restraint structure to protect the
plant environment during a steam pipe rupture event in a nuclear power plant. It focuses on
a structural component required to restrain the dynamic energy to an acceptable level.
Whip restraints used in the nuclear industry are typically honeycomb, U-bar and crush pipe
types. In this dissertation only the U-bar and crush pipe whip restraints will be considered.
The plant environment, with regards to pipe layout, plays a large role in determining the type
of restraint to be used, whether it is U-bar or crush pipe. A whip towards the wall/structure
will favor a crush pipe; a whip away from the wall/structure will favor a U-bar restraint. In this
project the crush pipe is selected where the whip is towards a wall/structure. The crush pipe
also represents a simpler design.
First-order analysis is performed using the energy method to determine the conceptual
geometry of the whipping component and the restraint geometry. Second-order analysis
includes finite element analysis to verify the first-order results. In this dissertation the concept
validation is done using LS-PrePost. for the pre- and post-processing while the analysis is
performed using LS-DYNA ®. During the second-order analysis it was demonstrated that the
energy is successfully absorbed by the crush pipe and thus the first-order analysis is
considered adequate.Thesis (MIng (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2013
3
Kane, Stephen James. « Two-phase flow of water and steam in a liquid metal fast breeder reactor pipe ». Thesis, University of Southampton, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261438.
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4
Du, Preez Christiaan. « Effect of graphitization on the static mechanical properties of service exposed ASTM A516 Gr. 65 steam pipe metal ». Thesis, Nelson Mandela Metropolitan University, 2017. http://hdl.handle.net/10948/22277.
Texte intégralRésumé :
The focus of this research project is to establish what effect graphitization has on the static mechanical properties of service exposed ASTM A516 Grade 65 steam pipe material, which operated for prolonged periods above 425 ̊C. The research study was conducted on three graphitized service exposed steam pipe weldment samples and on a newly welded and post weld heat treated sample with graphitized service exposed steam pipe material. Macro samples were removed from each of the samples at two positions and these were evaluated with regard to graphite nodule size, nearest neighbour spacing and % planar graphitization in the parent pipe and HAZ regions on either side of the welds. It was found on all of the service exposed samples that the graphite nodules of the HAZ regions have a smaller median nodule size, smaller median nearest neighbour spacing and increased % planar graphitization in comparison to the parent pipe material. The service expose parent pipe material on either side of the weldments of the respective samples was chemically analyzed. This was done with the focus being on the deoxidizing element content (Si and Al) of the respective parent pipe regions and to what extent these elements influenced the development of planar graphitization in these regions. No correlation could be identified between the level of deoxidizing elements and the levels of % planar graphitization in the parent pipe material. Tensile and Charpy impact samples were removed from the respective service exposed samples parent material on either side of the weld and from the HAZ regions on the side with the highest levels of planar graphitization. These samples were tested and the yield and ultimate tensile strength and Charpy impact toughness of the respective samples were then evaluated to establish how these static mechanical properties were influenced by the % planar graphitization. The yield and ultimate tensile strength of the service exposed material did not show a statistically significant correlation with the % planar graphitization. The Charpy impact toughness results did however show a statistically significant negative correlation towards the % planar graphitization. This was clearly evident from the results of the HAZ regions of the service exposed weldments (Samples A-C) which had the highest levels of % planar graphitization and the lowest impact toughness, while the newly welded and post weld heat treated Sample D had no planar graphitization outside the HAZ and the highest impact toughness. This research project not only investigated how planar graphitization affects the static mechanical properties of service exposed pipe material, it also investigated on a microstructural basis, how planar graphitization nucleates and grows. The microstructural investigation showed that the free carbon required for the development of planar graphitization originated from the regions outside the HAZ, which were formed when the pearlite bands were dissolved during the welding of the steam pipe. The heat input from the welding sensitized this region for the development of planar graphitization, probably due to the formation of a “carbon-rich” matrix due to the partial dissolution of the cementite precipitates. All the carbide precipitates in this region consisted of M3C. aluminium-rich precipitates were found inside newly nucleated graphite nodules, indicating its role as a possible heterogeneous nucleation site. Growth of newly formed graphite nodules showed a preference towards high-angle grain boundaries and regions with dislocations for the initial growth stages of the graphite nodules. The microstructure of the region outside the HAZ of the newly introduced seam weld on the service exposed steam pipe material (with graphitization), was also investigated using advanced electron microscopy methods and it yielded no evidence of the development of planar graphitization.
5
Tossey, Brett M. « Steam Oxidation Resistance of Shot Peened Austenitic Stainless Steel Superheater Tubes ». The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1306261300.
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Le, Kieu Hiep [Verfasser]. « Multiscale modeling of non-isothermal fluid transport in porous media : applications to loop heat pipe evaporator and superheated steam drying / Kieu Hiep Le ». Magdeburg : Universitätsbibliothek, 2017. http://d-nb.info/1155824369/34.
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7
Klíma, Martin. « Návrh konstrukce trubkového svazku generátoru páry ». Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-230296.
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Diploma thesis is focused on analisis of the steam generator tube bundle on the basis calculation by the finite elements method and softwaru ANSYS. Next it will also také account of job descriptions and methods of operation of the equipment propřed plan revision kontrol points that will be most critical. Annexes included documentary of model from the SolidWorks.
8
Lobo, Carlos Alexandre O. C. (Carlos Alexandre Orosco Caelho). « Filling strategies for avoiding water hammer in steam filled pipes ». Thesis, Massachusetts Institute of Technology, 1989. http://hdl.handle.net/1721.1/14484.
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9
Perez-Barbante, Dezire Q'anna. « IN-PLANE CYCLIC SHEAR PERFORMANCE OF PIPE STEM REINFORCED COB WALL ». DigitalCommons@CalPoly, 2019. https://digitalcommons.calpoly.edu/theses/2116.
Texte intégralRésumé :
This thesis investigates full-scale pipe stem reinforced cob walls under in-plane cyclic shear loads. Cob is the combination of clay subsoils, sand, straw and water that is built in lifts to produce monolithic walls. There is insufficient amount of information on cob as a building material in today’s age. The prior research that exists has examined varying straw content and type, water content, and mixture ratios to determine their effect on strength. There is currently one report that analyzes full-scale cob walls under in-plane loading. This thesis looks to iterate the full-scale tests and specifically studies the effect of reinforcement on cob walls. Concurrent to this research, another thesis was written that investigates a full-scale wire mesh reinforced cob wall under in-plane cyclic shear loads.
From the data collected, a shear failure was suggested for the stem pipe wall. There appeared to be a large amount of ductility from the data and the cracks formed. Ductility, a seismic response modification factor (R-Factor) and stiffness were calculated using the yield point and ultimate loads.Iterations of this research and those performed in the past can be helpful in integrating cob in to the California Building Code.
10
Salami, Najdat. « Gasification of Pine Wood Chips with Air-Steam in Fluidized Bed ». Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-234253.
Texte intégralRésumé :
Tato práce studovala vliv použití vzduchu a páry jako zplynovacího činidla ve zkapalňovacím generátoru plynu na vlastnosti vyprodukovaného plynu (oxid uhelnatý, vodík, obsah dehtu a nízká výhřevnost). Tato studie byla založena na experimentech které byly provedeny ve fluidním generátoru plynu Biofluid 100 v laboratoři Energetického ústavu technologické univerzity Brno s použitím páry jako zplynovacího činidla a borovicového dřeva jako výchozí suroviny. Cílem této dizertační práce je stanovit nejlepší provozní parametry systému při užití vodní páry a vzduchu ve zplynovacím zařízení biofluid 100, při kterých se dosáhne nejvyšší kvality plynu. K dosažení tohoto cíle bylo provedeno mnoho experimentů studujících účinky teploty reaktoru(T101), poměru páry a biomasy (S/B) poměru páry a vzduchu (S/A), teploty dodávané páry (Tf1), ekvivalentního poměru ER,ve složení vyprodukovaném plynu, výhřevnost, výtěžnost plynu, efektivnost přeměny uhlíku a účinnost zplynovače. Výsledky experimentů ukázaly, že zvýšení teploty reaktoru vede ke zvýšení obsahu vodíku a oxidu uhelnatého, výhřevnosti, výtěžnosti plynu, efektivnosti přeměny uhlíku, efektivnosti zplynovače a ke snížení obsahu dehtu. Příliš vysoká teplota reaktoru ale snižuje výhřevnost plynu. Dodáváním páry se zvýšila kvalita plynu, vyšší H_2,LHV a nižší obsah dehtu. Přesto ale nadměrné množství páry snižuje zplyňovací teplotu a tím i kvalitu plynu. Poměr páry a biomasy při kterém se dosáhne nejlepší kvality plynu se zvýší s teplotou reaktoru. Bylo zjištěno, že kdykoli byla teplota páry (Tf1) vyšší, byl plyn více kvalitní, ale zvyšování teploty páry také zvyšuje ekonomické náklady na vyprodukovaný plyn což se při masové produkci plynu musí brát v úvahu. Efekt ekvivalentního poměru ER, byl studován postupným zvyšováním, bylo zjištěno, že nejlepší ekvivalentní poměr pro dosažení nejvyšší kvality plynu byl kolem 0.29, při ER > 0.29 byl obsah hořlavého plynu snížen a to vedlo ke snížení kvality plynu. Obsah dehtu se snižuje jak zvýšením teploty reaktoru tak poměrem páry k biomase. Podle výsledků experimentů a diskuze, bylo zjištěno, že při použití směsi páry a vzduchu se kvalita plynu zvýší, parametry pro dosažení nejvyšší kvality vyprodukovaného plynu při experimentálních podmínkách jsou: T101 =829 S/B=0.67((kg steam)/(kg biomass)) ,S/A=0.67((kg steam)/(kg air)) , ER= 0.29 and a Tf1 je nejvyšší možná teplota,při které se vodík zvýší z 10.48 na 19,68% a výhřevnost z 3.99 na 5.52(MJ/m^3 ) a obsah dehtu z 1964(mg/m^3 ) na 1046(mg/m^3 ) zvýšením z 0 na 0.67 při T101=829 .
11
Yell, M. D. « Steam compression in the single screw compressor ». Thesis, University of Leeds, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372575.
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12
Olsen, Colin Andreas Dupont. « Empirical process modeling of the acid catalyzed steam pretreatment of radiata and lodgepole pine ». Thesis, University of British Columbia, 2012. http://hdl.handle.net/2429/43807.
Texte intégralRésumé :
Ethanol, an alternative liquid fuel, can be produced from sugars derived from lignocellulosic biomass in a bioconversion process that involves pretreatment, enzymatic hydrolysis, and fermentation. Among the different types of biomass investigated for bioconversion, softwoods are readily available in Canada, the US, and Scandinavia. Acid catalyzed steam pretreatment is a preferred method for softwoods due to its ability to effectively recover hemicellulose-derived sugars at moderate operating conditions. More severe conditions are generally required to produce a substrate readily hydrolyzed by enzymes, but because sugar degradation also occurs at these conditions, steam pretreatment is essentially a compromise.
Prediction of sugar recoveries from steam pretreated and enzymatically hydrolyzed softwood is desirable for the purposes of process control and steam pretreatment reactor design. In this thesis, efforts were made to determine whether response surface methodology or the thermal severity factors Ro and CS were better suited to the development of empirical models of steam pretreatment. The construction of the thermal severity factor models highlighted the predominance of temperature and time in determining the direct outcomes of the acid catalyzed steam pretreatment of radiata pine. Within a comparison of several response surface methodology models, a hybrid experimental design produced the most robust model because it was developed in conjunction with a narrow process space. Moreover, it was apparent that the response surface methodology models possessed the greater capacity for predicting the direct outcomes of steam pretreatment.
In an attempt to overcome limitations identified in the first portion of this thesis, the predictive capability of response surface methodology was further tested using lodgepole pine ranging in chip size and moisture content. The additional model created demonstrated that response surface methodology could successfully account for feedstock characteristics as well as steam pretreatment operating conditions. Moisture content, but not chip size, was shown to have a significant influence on the combined sugar recovery obtained after SO2 catalyzed steam pretreatment and subsequent enzymatic hydrolysis. In addition, model development was conducted in this portion of the thesis such that the model could form the basis of a more dynamic simulation of the entire softwood to bioethanol process.
13
Nakka, Ravi Kumar Nasrazadani Seifollah. « Flow accelerated corrosion experience at Comanche Peak Steam Electric Station ». [Denton, Tex.] : University of North Texas, 2008. http://digital.library.unt.edu/permalink/meta-dc-6072.
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14
Sevanto, Sanna. « Tree stem diameter change measurements and sap flow in Scots pine ». Helsinki : University of Helsinki, 2003. http://ethesis.helsinki.fi/julkaisut/mat/fysik/vk/sevanto/.
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15
Reeves, Christopher D. « Effectiveness of Elevated Skid Trail Headwater Stream Crossings in the Cumberland Plateau ». UKnowledge, 2012. http://uknowledge.uky.edu/forestry_etds/7.
Texte intégralRésumé :
One of the primary concerns associated with timber harvesting is the production of sediments from stream crossings. While research has shown that using improved haul road crossings can mitigate sediment production in perennial streams compared to the use of unimproved crossings little research has been undertaken on temporary skidder crossings of headwater streams, a situation common to a significant percentage of ground skidding operations. This experiment consisted of a controlled replicated testing of the effectiveness of four types of temporary skidder stream crossings (unimproved ford, corrugated culvert, wood panel skidder bridge, and PVC pipe bundle) relative to bedload and suspended sediment production. Automated samplers were used to monitor sediment and bedload production during the construction, use, removal, and post-removal phases associated with the use of these temporary crossings. Results showed that elevated crossings mitigated total sediment production compared to unimproved fords. Further, wood panel bridges yielded lower amounts of sediment than culverts but PVC pipe bundles show no difference between bridges or culverts. Sediment production varied by crossing type and use phase. While no differences were found among crossings types during construction, there was a difference between improved crossings and fords during use. Further, bridges and PVC pipe bundle crossings produced significantly less sediments than culverts during both their removal and during post-removal sampling and fords produced the largest amount of sediments during these phases.
16
Jiang, Lichun. « An evaluation of modeling techniques for stem taper, volume and weight for yellow-poplar and red pine in West Virginia ». Morgantown, W. Va. : [West Virginia University Libraries], 2007. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=5143.
Texte intégralRésumé :
Thesis (Ph. D.)--West Virginia University, 2007.Title from document title page. Document formatted into pages; contains ix, 111 p. : ill. (some col.). Includes abstract. Includes bibliographical references.
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Emebiri, Livinus Chinenye, et -. « Detection and Genetic Mapping of Quantitative Trait Loci Influencing Stem Growth Efficiency in Radiata Pine ». The Australian National University. Department of Forestry, 1997. http://thesis.anu.edu.au./public/adt-ANU20010822.164445.
Texte intégralRésumé :
Needle-to-stem unit rate (NESTUR) is a stem growth index of conifer seedling trees that measures the efficiency of stemwood production per unit of needle growth. Five experiments were carried out in this thesis using progenies of two unrelated full-sib radiata pine crosses. The initial experiment (experiment 1) applied the bulked segregant analysis technique to determine whether RAPD analysis could be successfully extended to the development of molecular markers for NESTUR in radiata pine. The NESTUR values of 174 progenies of the full-sib family 12038 x 10946 were determined. Based on the genotypic analysis of the individuals, two quantitative trait loci (QTL) controlling NESTUR were identified at ANOVA P-levels of 0.01-0.001. An absence of RAPD fragment markers generated by primers OPE-06 and OPA-10 was associated with low NESTUR values, while primer UBC-333 generated a 550 bp band that was associated with high NESTUR values. Linkage to components of NESTUR (increments in stem diameter and stem volume) was demonstrated for one of the QTL, while the other was unique to NESTUR, and not shared with the components. There was a significant interaction between the two QTLs. Presence of OPA-101200 locus appeared to inhibit expression of the QTL linked to UBC-333 [subscript 550].
¶
To further analyse the quantitative trait loci (QTLs) controlling NESTUR, a linkage map was constructed from RAPD markers segregating in 93 haploid progeny of another full sib cross (30040 x 80121) (experiment 2). Two hundred and sixty-two (262) markers were mapped to 14 linkage groups of at least 7 markers, ranging in size from 39 to 183 cM. The 14 linkage groups covered approximately 1511 cM of genetic map distance.
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In experiment 3, the linkage map was used to map QTLs controlling NESTUR, as well as increments in seedling stem diameter, volume, and height and needle volume. Altogether, five putative QTLs were detected for NESTUR, with explained variation ranging from 9 to 22%. Of the five QTLs detected, 3 were coincidental with those for stem growth in height, diameter and volume. The two QTL positions that were unique to NESTUR were flanked by QTLs for the component traits. Together, effects of the five QTLs explained 48% of the total phenotypic variation for NESTUR.
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Ability of identified markers to predict the phenotype and seedlings with growth potential was assessed in the cross 30040 x 80121, using six RAPD markers associated with NESTUR at ANOVA P-levels of 0.01-0.001 (experiment 4). The correlation between observed NESTUR and predicted values was 0.70. Differences in observed vs. predicted values were not large and did not indicate serious misclassifications, such as classification of an upper ranking individual into the lower group, or vice versa.
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Over a two-year growth period, the ability of NESTUR to predict stem growth was strongly affected by seedling age. In contrast, markers linked to NESTUR showed a consistent ability to predict stem growth, irrespective of seedling age. Compared with the top 1% of the original population, seedlings selected for their genotypic values showed a higher stem volume growth of 103% in the first year, and 76% in the second year.
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The expression of QTLs for stem volume, stem diameter, height, number of branches, number of whorls, and branches/whorl were compared at 5, 12, and 24 months of age. Two QTLs detected for height showed contrasting expression over two years, one was gradually reduced from LOD of 2.70 to 0.43 and the other increased from 1.12 to 2.45. Compared with the pattern observed for height, LOD scan profiles for diameter and volume showed less temporal change of peaks, suggesting that the genetic control for height growth is probably more unstable than that of diameter. QTLs controlling the phenotype at the time of measurement (ie the final phenotype) showed similar magnitude of effects on that trait's respective increments (or growth rate).
18
Nakka, Ravi Kumar. « Flow Accelerated Corrosion Experience at Comanche Peak Steam Electric Station ». Thesis, University of North Texas, 2008. https://digital.library.unt.edu/ark:/67531/metadc6072/.
Texte intégralRésumé :
Flow accelerated corrosion (FAC) is a major concern in the power industry as it causes thinning of the pipes by the dissolution of the passive oxide layer formed on the pipe surface. Present research deals with comparing the protection offered by the magnetite (Fe3O4) versus maghemite (γ-Fe2O3) phases thickness loss measurements. Fourier transform infrared spectroscopy (FTIR) is used in distinguishing these two elusive phases of iron oxides. Representative pipes are collected from high pressure steam extraction line of the secondary cycle of unit 2 of Comanche Peak Steam Electric Station (CPSES). Environmental scanning electron microscopy (ESEM) is used for morphological analysis. FTIR and X-ray diffraction (XRD) are used for phase analysis. Morphological analysis showed the presence of porous oxide surfaces with octahedral crystals, scallops and "chimney" like vents. FTIR revealed the predominance of maghemite at the most of the pipe sections. Results of thickness measurements indicate severe thickness loss at the bend areas (extrados) of the pipes.
19
Speer, James H., et Richard L. Holmes. « Effects of Pandora Moth Outbreaks on Ponderosa Pine Wood Volume ». Tree-Ring Society, 2004. http://hdl.handle.net/10150/262634.
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Coloradia pandora (Blake) is a phytophagous insect that defoliates Pinus ponderosa (Dougl. ex Laws.) in south-central Oregon. Little is known about the extent of damage this insect inflicts upon its host trees during an outbreak. In this paper, we present stem analyses on four dominant Pinus ponderosa trees that enable us to determine the amount of volume lost during each Coloradia pandora outbreak on this site for the past 450 years. We found that on average an outbreak inhibits radial growth so that an individual tree produces 0.057 m³ less wood volume than the potential growth for the duration of an individual outbreak. A total of 0.549 m³ of growth per tree was inhibited by 10 outbreaks during the lifetime of the trees, which, in this stand, equates to 9.912 m³/ha (1,700 board feet/acre) of wood suppressed over the last 450 years throughout the stand. Our results do not support previous findings of a lag in suppression onset between the canopy of the tree versus the base. Crossdating of stem analysis samples is paramount to definitively examine the potential for a lagged response throughout the
20
Rune, Göran. « Instability in plantations of container-grown Scots pine and consequences on stem form and wood properties / ». Uppsala : Dept. of Forest Products and Markets, Swedish Univ. of Agricultural Sciences, 2003. http://epsilon.slu.se/s281-ab.html.
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McEwen, Amiana Marie. « Abundance, Distribution, and Geometry of Naturally Occurring Macropores in Stream Banks ». Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/95948.
Texte intégralRésumé :
Preferential flow paths are areas of substantially higher permeability than surrounding media. Macropores and soil pipes are a type of preferential flow path where conduit-like voids in the subsurface are typically greater than three millimeters in diameter. They are known to occur in agricultural and forest soils, often as a result of biological and physical processes. Macropores also exist in stream banks and have the potential to enhance the exchange of water and solutes between the channel and riparian groundwater, yet the geographic distribution of bank macropores is unknown. Here we determined the abundance, distribution, and geometry of naturally occurring surface-connected macropores in the banks of 20 streams across five physiographic provinces in the Eastern United States. We identified a total of 1,748 macropores, which were present in all 20 streams, with 3.8 cm average width, 3.3 cm average height, 11.5 cm average depth, and 27.9 cm average height above water surface elevation. Macropore abundance, distribution and geometry were statistically different between physiographic provinces, stream orders, and soil textures, with the latter being the most important. Macropores tended to be larger and more abundant in soils with a high cohesiveness and a low hydraulic conductivity compared to soils with a low cohesiveness and high hydraulic conductivity. As a result, streams with greater longitudinal heterogeneity of soil texture also had greater heterogeneity of macropore density. However, macropore size and height above baseflow water surface elevation also increased with stream order and therefore stream size. This work represents the first attempt to characterize macropores across a variety of riverine systems and presents evidence that macropores may play an important role in hyporheic exchange within stream banks. These results may have water quality implications, where macropores may enhance hyporheic exchange yet reduce the filtering capacity of riparian buffer zones.MS
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Loubser, Karl Albie. « An experimental study of an inherently-safe, natural circulating, flash-tube type system for a nuclear reactor steam supply concept ». Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/96050.
Texte intégralRésumé :
Thesis (MEng) -- Stellenbosch University, 2014.ENGLISH ABSTRACT: This project investigates aspects of a novel inherently safe nuclear power steam supply system as safety is of paramount importance. The system envisaged has unique features namely: a) a two-phase flow flash-tube type natural circulating primary loop (also the secondary radioactive particle containment); b) a twophase flow thermosyphon heat pipe type heat exchanger secondary loop is used to transfer heat from the primary loop to the steam generators, thereby physically separating the two flow streams from one another; c) a natural convection air cooled condenser for the removal of the reactor’s residual heat; d) a unique core using TRISO type fuel (acting as the primary radioactive particle containment) with life of at least 8.9 years; e) a steel containment vessel acting as a tertiary radioactive product containment; f) a concrete containing structure with air vents to allow air to pass over the main steel containment vessel for cooling purposes in the case of an emergency, and for the removal of parasitic heat during operation. In particular the primary and secondary loops of the proposed system are investigated. This is done by design, construction and testing of a small scale experimental set-up of the primary and secondary loops as well as the development of theoretical models for the two loops. A literature survey focusing on nuclear technology, thermosyphon loops, natural circulating loop instabilities, heat pipes, and two-phase flow modelling is presented to give a brief overview of the technologies as well as tools used in the work undertaken. Observations of the inside flow behaviour of the primary loop experimental set-up were made possible by windows providing many insights into the inner workings, such as plume formation and geysering. The transient response of the secondary heat pipe loop start-up is also investigated. A thermal resistance theoretical model was developed for the secondary loop using heat transfer formulae from theory as well as experimentally semiempirical correlated formula. Different states of operation of the secondary loop were observed during testing with the theoretical model of the condensing regime correlating well, two-phase regime correlating acceptably and liquid regime correlating poorly to experimental results and thus were modelled using an experimentally determined overall heat transfer coefficient. The secondary loop model of the liquid regime is coupled with the primary loop theoretical model to predict the system’s performance. A homogeneous, one-dimensional, simple theoretical model for the primary loop was derived and computer simulated. The results did not compare well with experimental results for single phase flow and failed to capture the onset of two-phase flow. The assumptions of one dimensional model with a unidirectional flow, a hydrostatic pressure problem, a constant volumetric flow rate and the inability of the implementation of the code to handle expansion are noted as some of the flaws in the theoretical model. The following recommendations are made: a more advanced design of the pressuriser should be incorporated into the experiment; the secondary loop’s theoretical model should be characterised under a broader set of operating conditions; the computer program can be used as the basis for further research and implementation of alternative solution algorithms and models.
AFRIKKANSE OPSOMMING: Hierdie projek ondersoek aspekte van ’n ongewone, essensieel veilige kernkrag stoomtoevoer-stelsel, omdat veiligheid van kardinale belang is. Die stelsel wat voorgestel is, het unieke eienskappe, naamlik: a) ’n twee-fasevloei flits-buistipe natuurlik sirkulerende primêre lus (wat ook die sekondêre inperking van radioaktiewe materiaal bevat); b) ’n twee-fasevloei termo-heweleffek sekondêre lus hitte-pyp hitte-uitruiler word gebruik om die hitte vanaf die primêre lus oor te dra na die stoomkragopwekkers en daardeur word die twee strome se vloei fisies geskei van mekaar; c) ’n natuurlike konveksie lugverkoelde kondensor word gebruik vir die verwydering van die reaktors se oortollige hitte; d) ’n unieke kern gebruik TRISO-tipe brandstof (wat as die primêre inperking van radioaktiewe materiaal optree) met ’n lewe van minstens 8.9 jaar; e) ’n inperkingshouer van staal wat optree as ’n tersiêre radioaktiewe produkhouer; f) ’n betonstruktuur met lugventilasie om toe te laat dat lug oor die hoof staalhouer vloei vir verkoeling in ’n noodgeval, en vir die verwydering van parasitiese hitte tydens werking. Hoofsaaklik word die primêre en sekondêre lusse van die voorgestelde stelsel ondersoek. Dit word gedoen deur die ontwerp, konstruksie en die toets van ’n eksperimentele opstelling van die primêre en sekondêre lusse op klein skaal, sowel as die ontwikkeling van teoretiese modelle vir die twee lusse. ’n Literatuurstudie wat fokus op kerntegnologie, termo-heweleffeklusse, natuurlik sirkulerende lus instabiliteit, hitte-pype, en twee-fase vloeimodellering word aangebied om ’n kort oorsig te gee van die tegnologie, sowel as gereedskap gebruik in die werk wat onderneem is. Om die interne vloeigedrag van die primêre lus se eksperimentele opstelling waar te neem, word daar gebruik gemaak van vensters wat dien as ’n manier om die innerlike werking van die proses soos pluimvorming en die kook van die water in die warmwaterkolom te toon. Die oorgangsreaksie van die sekondêre hittepyplus aanvangs is ook ondersoek. ’n Teoretiese termiese weerstandmodel is ontwikkel vir die sekondêre lus met behulp van hitte-oordragformules waarvoor hitte-oordragteorie gebruik is, wat met eksperimentele semi-empiriese formules gekorreleer is. Verskillende toestande van die sekondêre lus se werking is waargeneem gedurende die toetse. Die teoretiese model het goed met die kondensasiestaat gekorreleer, terwyl by die twee-fasewerkswyse aanvaarbare korrellasies aangetref is en die uiteindelike vloeitoestand swakker gekorrelleer het met eksperimentele resultate en dus gemodelleer is met behulp van die NTU-effektiwiteitsmetode. Die sekondêre lusmodel van die vloeistoftoestand is gekoppel met die primêre lus teoretiese model om die werking van die stelsels te voorspel. ’n Homogene een-dimensionele eenvoudige teoretiese model van die primêre lus is afgelei en ’n rekenaar simulasie is uitgevoer. Die resultate vergelyk nie goed met die eksperimentele resultate vir enkelfasevloei en kon nie die aanvang van twee-fasevloei beskryf nie. Die aannemings van ’n een-dimensionele model met eenrigting vloei, ’n hidrostatiese druk probleem, ’n konstant volumetries vloeitempo en die onvermoë van die implementering van die kode om uitbreiding te hanteer is bekend as ’n paar van die foute in die teoretiese model. Die volgende aanbevelings word gemaak: ’n meer gevorderde ontwerp van drukreëlaar moet in die eksperiment ingesluit word; die sekondêre lus se teoretiese model moet gekenmerk word onder ’n wyer stel bedryfsomstandighede, en die rekenaar program kan gebruik word as die basis vir verdere navorsing en die implementering van alternatiewe algoritmes en modelle.
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Attaoui, Pascale. « Analyse d'images obtenues par balayage de surface avec un capteur ponctuel courants de Foucault ». Gif-sur-Yvette : Commissariat à l'énergie atomique, 1994. http://catalogue.bnf.fr/ark:/12148/cb35748414t.
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Miller, Dominique. « Contribution à l'étude et à la réalisation d'une sonde multi-éléments à courants de Foucault et de l'instrumentation associée, destinée à la détection et la reconstruction tomographique de défauts dans les tubes de générateurs de vapeur ». Cachan, Ecole normale supérieure, 1998. http://www.theses.fr/1998DENS0039.
Texte intégralRésumé :
Compte-tenu des progrès en matière de modélisation des dispositifs à courants de Foucault, et de résolution des problèmes inverses, on peut espérer pouvoir utiliser bientôt les outils de l'imagerie pour la reconstruction de défauts de pièce métalliques. Encore faut-il disposer d'un capteur approprie, qui échantillonne correctement le champ magnétique et qui soit modélisable. Dans cette thèse, nous présentons les pré déterminations nécessaires à la réalisation d'un capteur multiéléments, dans le cadre du contrôle à grande vitesse de tubes de générateurs de vapeurs. Cela conduit en la conception d'une sonde de type microsystème, avec détecteurs sur silicium et électronique de conditionnement embarquée. Par ailleurs, la reconstruction tomographique étant une opération coûteuse en temps de calcul, et elle ne doit être appliquée que sur des zones suspectes. Nous proposons un pré traitement rapide et efficace, base sur l'analyse en composantes principales pour détecter de telles zones, malgré un rapport signal à bruit souvent très mauvais. L'ensemble sonde/pré traitement donne des résultats très satisfaisant en termes de détection, et doit permettre par la suite une reconstruction tomographique des défauts.
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Barbotteau, Yves. « Recherche des modifications de caractéristiques dans des biomatériaux en verre bioactif par des méthodes nucléaires et physico-chimiques ». Phd thesis, Clermont-Ferrand 2, 2002. http://www.theses.fr/2002CLF21360.
Texte intégralRésumé :
Les biomatériaux à usage orthopédique posent le problème de leur devenir dans l'organisme. Lorsqu'ils sont métalliques, ils posent le problème du relargage de métaux dans les tissus voisins. L'alliage de titane Ti6AI4V est utilisé pour ses bonnes propriétés mécaniques et pour sa résistance à la corrosion. L'usage d'un revêtement permet d'améliorer encore ses performances. J'ai étudié deux revêtements en verre référencés BVA et BVH. La caractérisation in vivo et in vitro a été menée grâce à plusieurs techniques complémentaires d'analyse : microscopies électroniques et méthodes nucléaires (PIXE. . . ). Le verre BVA s'est révélé être bioactif. Il se transforme en un gel de silicium avec incorporation de protéines et d'oligo-éléments (Zn et Sr), et ce, dès 3 mois après implantation. Ce gel disparaît peu à peu et est remplacé par un os néoformé. Cet os a été analysé comme mature après un an d'implantation ; il assure une meilleure ostéointégration de l'implant. Quant au verre BVH, il est bioinerte. Sa composition est constante au cours du temps. Cependant, la formation d'une interface de 2 µm d'épaisseur, induite par le processus de dépôt du revêtement, fragilise les liaisons inter-granulaires. Cela se traduit par la fragmentation du revêtement et la migration de grains de verre à travers le réseau lacunaire de l'os environnant. Les deux verres sont une barrière efficace contre la corrosion de l'alliage, tant qu'ils restent en place. J'ai proposé les bases d'une nouvelle méthodologie d'analyse : la combinaison de la cartographie PIXE et de l'histopathologie. Le principal intérêt est de corréler une éventuelle réponse tissulaire à la présence de certains éléments atomiques. J'ai introduit pour la première fois la théorie de la percolation pour essayer de modéliser la résorption de biomatériaux poreux tel que le corail et les hydroxyapatites. Les premières simulations sont très prometteuses et rendent bien compte de plusieurs résultats expérimentaux observés
26
Klinka, Karel, Han Y. H. Chen, Qingli Wang et Christine Chourmouzis. « Height growth curves and site index tables for subalpine fir, Engelmann spruce, and lodgepole pine in the ESSF zone of BC ». Forest Sciences Department, University of British Columbia, 1998. http://hdl.handle.net/2429/768.
Texte intégralRésumé :
Height growth models of coastal low- and mid-elevation Pacific silver fir, low-elevation white spruce, and low- and midelevation
lodgepole pine have been used for predicting productivity of subalpine fir, Engelmann spruce, and lodgepole
pine, respectively. These models, however, are biased in predicting height growth of high-elevation subalpine fir, Engelmann
spruce, and lodgepole pine.
To improve this situation, 329 sample plots (165 for subalpine fir, 90 for Engelmann spruce, and 74 for lodgepole pine)
were located throughout the Engelmann Spruce-Subalpine Fir (ESSF) zone. Stem analysis was carried out on three
dominant trees in each 0.04 ha sample plot. For each study species, a height growth model was developed on the data
from two-thirds of the sample plots using the conditioned Chapman-Richards’ function; the model was validated using
the remaining one-third of the sample plots.
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Ptáček, Ondřej. « Návrh dvoutlakého vertikálního kotle na odpadní teplo za plynovou turbínou na zemní plyn ». Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2017. http://www.nusl.cz/ntk/nusl-319246.
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This diploma thesis deals with proposal of a two-lane vertical boiler using the waste heat after gas turbine. In the first part the heat calculation has been done followed by the arrangement of particular heat exchange surfaces and the drawing of real saw diagram. There are also dimensions of drums, inlet and outlet pipes and transfer pipelines drafted. Furthermore, I have listed the materials that are used for casing the boiler and pipelines. Finally, the boiler loss is calculated and the boiler hydraulic calculation is performed. The supplement contains a boiler drawing.
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Richter, Štěpán. « Studie možnosti vybudování malých vodních nádrží v lokalitě u Vyškova na Moravě ». Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2012. http://www.nusl.cz/ntk/nusl-225619.
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This thesis deals with the design of small reservoirs at Vyškov na Moravě. Projected reservoirs’ dams are earth-fill and homogenous and each one is equipped with the bottom water outlet and the emergency spillway. The first reservoir, located on the tributary of the Drnůvka river, has the fountain type emergency spillway and the feed pipe bottom water outlet. The reservoir of the Merchanice river, situated at the Vyškov airport, is equipped with the lateral emergency spillway and the feed pipe bottom water outlet. The third design is the reconstruction of the Marchanka reservoir projecting the dam raise. For this small reservoir two variants of functional installations were elaborated.
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Majek, Dee. « Big Content's Big Blunders : Anti-piracy measures in the entertainment and copyright industries ». Thesis, Stockholms universitet, Institutionen för mediestudier, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-107225.
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This thesis examines the on-going anti-piracy and anti-file sharing measures taken by media conglomerates and big content as misguided attempts at addressing changing consumer expectations and social and technological norms. These measures include legislation such as the Stop Online Piracy Act (SOPA), Preventing Real Online Threats to Economic Creativity and Theft of Intellectual Property Act (PIPA), Anti-Counterfeiting Trade Agreement (ACTA), and Cyber Intelligence Sharing and Protection Act (CISPA); and litigation against both extremes of the spectrum: from the world's largest file sharing search engines like The Pirate Bay, and cyberlockers like MegaUpload, to private citizens who illegally downloaded a few movies or a few songs. The manner in which the entertainment industry's largest, most expensive, and highest-profile anti-piracy measures in the recent years have been received by groups from IT corporations to human rights organizations, researchers, politicians, legal and internet experts, and millions of citizens worldwide are of focus; and how this translates into an unpopular public image is explored. Piracy is underlined as a service and distribution problem, and various international studies are presented in exploring the relationship between illegal downloading and legal purchases.
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Med, Lukáš. « Návrh dvoutlakého horizontálního kotle na odpadní teplo ». Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2016. http://www.nusl.cz/ntk/nusl-241924.
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This master's thesis deals with thermal calculation and design of proportions of calorific components of a heat recovery steam generator (HRSG), which is placed behind a combustion turbine, for given parameters of exhaust gases and requested parameters of steam. In the first chapters is described the design, layout of HRSG and the thermal calculation. The next parts deal with the design of flue-gas duct and each individual heating surface. Next section shows computations of dimensions of drums, flooding pipes, transferring pipes and all other outer pipes. The chosen materials are described in one of the last chapters and the last chapter deals with calculation of draft loss of steam generator.
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Morávek, Aleš. « Hydraulický agregát pro regulaci parní turbíny ». Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2016. http://www.nusl.cz/ntk/nusl-254353.
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This diploma thesis is focused on the design of high-pressure hydraulic unit to drive a regulation of condensation turbine. The aim is to calculate all the elements of the hydraulic system, piping design and the necessary drawings. The entire assembly consists of purchased parts from other manufacturers. Major oil tank and a safety catch tank is described in detail and will be made, not bought.
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Blinková, Magdaléna. « Založení stavby ve složitých základových poměrech ». Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2017. http://www.nusl.cz/ntk/nusl-265337.
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The subject of this diploma thesis is the design of deep foundation highway bridge on D3 motorway in km 112.574, over Bošilecký stream and evaluation of geomorphological, geological and hydrogeological conditions and perform static calculation bridge foundation
33
Guibert, Geoffroy. « Etude par des méthodes nucléaires et physico-chimiques de la contamination des tissus situés autour de biomatériaux métalliques implantés ». Phd thesis, Clermont-Ferrand 2, 2004. http://www.theses.fr/2004CLF21506.
Texte intégralRésumé :
Les implants utilisés comme biomatériaux sont fonctionnels, biocompatibles et certains bio-actifs. Il existe quatre familles de biomatériaux : les métaux et les alliages, les céramiques, les polymères et les matériaux naturels. Des phénomènes d'usure (corrosion, frottement) génèrent des débris dans l'organisme. Ces débris engendrent différents problèmes : toxicité, réactions inflammatoires, descellements prothétique par lyse osseuse. Nature, taille, morphologie, quantité des débris sont des paramètres qui influencent les réactions biologiques susceptibles de se produire. Nous avons caractérisé la contamination métallique (migration, comportement in vivo, quantité, taille et nature des débris) provenant des prothèses de genou au niveau du tissu capsulaire voisin. Les méthodes PIXE-RBS et STEM-EDXS, principalement employées, sont des outils complémentaires. Les débris sont répartis de façon hétérogène dans l'articulation du genou. Ils migrent sur plusieurs milliers de µm en profondeur. Pour les échantillons fortement pollués, les débris sont des grains d'alliages de dimension de l'ordre de µm (PIXE). Les rapports massiques in vivo confirment la stabilité chimique des grains de TA6V et l'évolution des grains de CrCoMo. Une étude à l'échelle nanométrique (STEM-EDXS) montre une dissolution de grains de TA6V (µm) en de plus petits (nm). Localement la présence de grains alpha indiquerait une dissolution préférentielle de la phase bêta (joint de grain) avec largage de A1 et V éléments carcinogènes et toxiques. Le développement d'un protocole PIXE-histologie en cible mince, corrèle une analyse PIXE et histologique sur une même zone. Ce protocole informe sur les pathologies liées aux contaminations métalliques, même si leur teneur est de l'ordre du µg/g, grâce à la sensibilité de la méthode PIXE. De plus l'innocuité vis-à-vis de la radioactivité de plusieurs biomatériaux naturels ou synthétiques est établie, à l'aide de système de détection y ultra bas bruit de fond
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SHANKER, PRASHANT KUMAR. « THERMAL AND COST ANALYSIS OF INSULATING MATERIALS FOR STEAM PIPE ». Thesis, 2023. http://dspace.dtu.ac.in:8080/jspui/handle/repository/19968.
Texte intégralRésumé :
This Project aims to determine the economic insulation thickness for various materials
and perform a thermal analysis to find the insulation material thickness's heat flux and
temperature distribution. We also conduct a cost analysis to find the minimum cost
according to a MATLAB program's economic insulation thickness. Finally, we calculate
the payback period using the heat flux with and without insulation. To achieve these
objectives, we develop a MATLAB program that finds the economic insulation
thickness for a given set of parameters such as temperature difference, insulation
conductivity, outside convective heat transfer coefficient, etc. The program outputs the
consistency required to minimise insulation cost and heat loss. We then use this
thickness value in ANSYS to create the 2D geometry of the steam pipe with insulation.
After completing the geometry, we perform a thermal analysis on ANSYS Fluent to find
the insulation material's heat flux and temperature distribution. Finally, we conduct
thermal research for different insulation materials and compare the results to determine
the most effective insulation material in reducing heat loss. Once we obtain the heat flux
values, we perform a cost analysis to determine the savings from insulation. Cost saving
includes considering the initial cost of insulation and the yearly savings in energy costs.
We also calculate the payback period to determine the time it would take for the
insulation to pay for itself. From the results we obtain, we observe that the directional
heat flux plays a crucial role in determining the performance of the insulation material.
A higher directional heat flux in the insulation material indicates better insulation
performance. In conclusion, this project provides a comprehensive approach to finding
the economic thickness of insulation, determining the thermal performance of insulation
materials and analysing the cost and payback period of insulation. These findings can be
used to select insulation materials for steam pipes and design energy-efficient systems.
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Huang, Tsung-Yuan, et 黃琮元. « Computer Aid Design and Experiments on Double Pipe Heat Exchangers Subject to Ultra-Supercritical Steam ». Thesis, 2012. http://ndltd.ncl.edu.tw/handle/39537050334084050626.
Texte intégralRésumé :
碩士國立臺灣海洋大學
機械與機電工程學系
100
The increase in the temperature and pressure can effectively enhance the efficiency of power generation. The current operating range of steam has reached the ultra-supercritical state. The thermal physical properties subject to high temperatures and pressures of steam have been investigated in this thesis, especially at the critical point. To achieve the goal, the safety wall thickness of a pipe at a specified pressure and temperature was calculated according to the specification of CNS. The detailed procedure was written in an EXCEL code and it can be executed in a personal computer. The data base includes SUS-316L and Inconel-718 which facilitates the information of physical property during the calculation. Based on a designate pressure of 400 atm and the maximum temperature up to 760 ℃, an experimental device has been established by TPRI to study the effect of erosion. The thermal behavior of all the heat exchangers in this loop was investigated in this work. LMTD method has been used to estimate the heat transfer area in the design of double pipe heat exchangers. The experiments were also conducted. The deviation between theory and data is about 5% in a flow rate of 300kg/hr, whereas it increases to 50% in a test of 180kg/hr. It is doubted that the reason was due to low mass flow rate in which Reynolds number falls into the laminar flow regime maybe the eccentric allocation in double pipes. Usually, once-through type boilers have been used in a supercritical power plant. The heating pipes in is type of boiler is subject to the risk of dryout and burnout. A new generation of super-critical boiler bore pipe uses the rifled tube, internally rifled tube allows fluid rotation to produce centrifugal force, the bubble is moved toward the centerline of the tube. Hence the dryout phenomenon can effectively delay.
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Chung, Chen-LIN, et 鍾承麟. « Computer Codes to Investigate the Thermal Performance of Double-Pipe Heat Exchangers and Boiler Tubes with High Pressure Water Steam ». Thesis, 2015. http://ndltd.ncl.edu.tw/handle/38020230687475521384.
Texte intégralRésumé :
碩士國立臺灣海洋大學
機械與機電工程學系
103
The variations of temperature dependent properties of water are studied especially at saturation state and near the critical point. The thermal conductivity as well as viscosity is observed to appear a minimum in the supercritical region, and the relations to pressure have been developed. This study is also interested in the thermal performance of heat exchangers established by Taipower Company. Three cases have been conducted at subcritical and supercritical pressures. Through a series of calculations, the overall heat transfer coefficient can be estimated. When the temperature falls in the low or high regime, the error is around 10%. Whereas the error increases up to 50% while the range of temperature includes either the saturation or pseudo-critical conditions. Similar results were detected in many literatures. Furthermore, the heat transfer coefficients obtained in the present code are compared favorably with the experimental data by China in both tube and annular sides. Finally, the absence of applied heat flux in the present formulas may be expected to play an important role in the further thermal analysis. Nusselt number is an index of heat transfer ability. Some famous empirical correlations were investigated, but none of them can fit the data in the neighborhood of critical point. In addition, the phenomenon of heat transfer deterioration (HTD) was observed near the pseudo critical condition which may result in crack of a boiler tube. A computing program coded in Visual-Basic has been developed to simulate the thermal behavior inside the heated tube. The predicted temperature is made to compare favorably with experimental results. Referencing the facilities in many foreign countries, some suitable sizes of test piece and the installation of thermocouples are recommended. The operating condition including temperature, pressure, mass flux as well as power supply is all investigated which provides Taipower Company to construct the test apparatus
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Чернова, Юлія Ігорівна. « Підвищення енергетичної ефективності жаротрубного парового котла VSP-1000 в умовах Концерну «Міські теплові мережі» м. Запоріжжя ». Магістерська робота, 2020. https://dspace.znu.edu.ua/jspui/handle/12345/2159.
Texte intégralRésumé :
Чернова Ю. І. Підвищення енергетичної ефективності жаротрубного парового котла VSP – 1000 в умовах КОНЦЕРНУ «МТМ» м. Запоріжжя : кваліфікаційна робота магістра спеціальності 144 "Теплоенергетика" / наук. керівник Ю. М. Каюков. Запоріжжя : ЗНУ, 2020. 96 с.UA : Робота викладена на 96 сторінках друкованого тексту, містить 5 таблиці, 4 рисунки. Перелік посилань включає 20 джерел з них на іноземній мові 0. В дипломній роботі розглянуто питання про дослідження теплообміну для удосконалення конструкції жаротрубного котла та вплив аеродинамічних параметрів на його роботу. Розроблено вісім креслень та презентація в яких наведено шляхи підвищення ефективності парового котла.
EN : The work is presented on 96 pages of printed text, contains 5 tables, 4 figures. The list of references includes 20 sources, 0 of them in foreign language. The thesis deals with the issue of the study of heat exchange to improve the design of the fire-tube boiler and the influence of aerodynamic parameters on its work. Eight drawings have been developed and a presentation on how to improve the efficiency of a steam boiler.
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Chen, Kuan-You, et 陳冠友. « Steam Condensation and Transport in Micro-Grooved Pipes ». Thesis, 2005. http://ndltd.ncl.edu.tw/handle/93274487998540913918.
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Lin, Shish-Cho, et 林士▉. « TORSIONAL BEGANIOR OF SINGLE STEAL-PIPE PILES IN SATURETED SAND ». Thesis, 1993. http://ndltd.ncl.edu.tw/handle/81367687012227672105.
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Eichenberg, Thomas William. « Numerical analysis of condensation induced water-hammer in horizontal piping systems ». Thesis, 1990. http://hdl.handle.net/1957/38056.
Texte intégralRésumé :
Condensation Induced Water-Hammer, CIWH, has been an
historical problem for the nuclear power industry over the
past 2 decades. It has caused damage to plant systems, and
considerable anguish to plant operators. This thesis has
embarked on an attempt to characterize the fluid motion, heat
transfer, mixing, and stability of a horizontal, stratified
flow of steam over subcooled water.
A literature review was conducted to determine the state
of numerical and analytical methods which have been applied
to this problem. The result of the review has led to the
implementation of new analytical interfacial stability
models. Information from the review has also led to the
development of correlations for wave frequency and amplitude
on the phase interface.
A numerical model has been developed to estimate the
temperature profile on the phase interface. Also, the model
will construct, by use of the above correlations, an estimate
of the interface wave structure. This wave structure is then
evaluated against a non-linear model for interface stability
to determine the onset of slug formation.
The numerical model has been used to evaluate two known
CIWH events. The results indicate that the onset of slug
formation is necessary, but not sufficient, to ensure a
water-hammer event. The results imply that there is the
possibility that once a slug has formed, it may break up
before a trapped steam void can fully collapse. The model
also indicates that CIWH in steam generator, feedwater nozzle
sections is not due to the formation of slug on an unstable
phase interface. Rather, CIWH may occur when the liquid
level inside of the feedwater nozzle is above the top of the
feedring, thus creating an isolated steam pocket. The rapid
condensation of the trapped steam in the causes CIWH. This
particular result implies that it may be possible to completely
avoid CIWH in the feedwater nozzle altogether.Graduation date: 1991
41
李汎濱. « Chemical and bioactive constituents of the stem of piper arborescens ». Thesis, 2002. http://ndltd.ncl.edu.tw/handle/16748590935680540822.
Texte intégralRésumé :
碩士高雄醫學大學
天然藥物研究所
90
ABSTRACT Investigation on the CHCl3 souble part of the stem of Formosan Piper arborescens Roxb.(Piperaceae), has led to the isolation of twenty-one compounds including sixteen alkaloids：two simple pyridones, 5,6-dihydro-2(1H)-pyridone (1)、piplartine (2)；seven cyclobutanoid amides, piplartine-dimer A (3)、piperarboresine (4)、piperarborenine A (5)、piperarborenine B (6)、piperarborenine C (7)、piperarborenine D (8)、piperarborenine E (9)；two dioxoaporphines, cepharadione B (14)、1,2,3-trimethoxy-4,5-dioxo-6a,7-dehydroaporphine (15)；five aristolactams, cepharanone B (16)、piperolactam B (17)、piperolactam C (18)、aristolactam BⅢ (19)、goniothalactam (20)；and two lignans, (+)-diayangambin (12)、(+)-arborone (13)；two phenylpropanoids, methyl trans-3,4,5-trimethoxycinnamate (10)、methyl cis-3,4,5-trimethoxycinna- mate (11)；and 4-acetonyl-3,5-dimethoxy-p-quinol (21). Among the isolates, compounds 5~9 and 13 were new compounds. The known compounds 16~20 of aristolactam type, were isolated for the first time from this plant. The structures of the isolated compounds were elucidated by spectroscopic analysis. Compound 2 and 17 revealed antiplatelet aggregation activity at 100 and 50μg ml-1 induced by AA and collagen, compound 7 and 10 showed antiplatelet aggregation activity at 100μg ml-1 induced by collagen, compound 12 showed inhibitory activity on platelet aggregation at 100 and 50μg ml-1 induced by PAF. Additionally, compound 2, 4~9, 19 and 20 showed significant cytotoxicity against P-388, A549 and HT-29 cancer cell lines in vitro.
42
Espinoza, Jesus Alberto. « Genetic and nutritional effects on stem sinuosity in loblolly pine ». 2009. http://www.lib.ncsu.edu/theses/available/etd-01172009-084805/unrestricted/etd.pdf.
Texte intégral
43
LeBude, Anthony Vincent. « Adventitious rooting and physiology of stem cuttings of loblolly pine ». 2005. http://www.lib.ncsu.edu/theses/available/etd-04122005-152359/unrestricted/etd.pdf.
Texte intégral
44
HUANG, CHEN-HAO, et 黃陳浩. « A physical model for^^heat transfer in turbulent steam-water droplet flows in vertical pipes ». Thesis, 1986. http://ndltd.ncl.edu.tw/handle/66226675873003057062.
Texte intégral
45
Wood, Elizabeth Rachel. « Clonal variation of stem taper in loblolly pine (Pinus taeda L.) ». 2009. http://www.lib.ncsu.edu/theses/available/etd-10292009-195937/unrestricted/etd.pdf.
Texte intégral
46
Zhang, J., X. Lin, R. Wang, Yakun Guo, C. Zhang et Y. Zhang. « Flow structures in wake of a pile-supported horizontal axis tidal stream turbine ». 2019. http://hdl.handle.net/10454/17796.
Texte intégralRésumé :
YesThis study presents results from laboratory experiments to investigate the wake structure in the lee side of a scaled three-bladed horizontal axis tidal stream turbine with a mono-pile support structure. Experiments are conducted for a range of approaching flow velocity and installation height of rotor. Analysis of the results shows that bed shear stress increases with the increase of approaching velocity and decrease of installation height within 2D (D is the diameter of the rotor) downstream of the rotor. The flow field within 2D downstream of the rotor is greatly influenced by the presence of nacelle and mono-pile. Low stream-wise flow velocity and large turbulence intensity level is detected along the flume center right behind the nacelle and mono-pile from 1D to 2D downstream of the rotor. Stream-wise velocity at the blade tip height lower than the nacelle increases sharply from 1D to 2D and gradually grows afterwards. Correspondingly, the turbulence intensity decreases quickly from 1D to 2D and slowly afterwards. Large bed shear stress is measured from 1D to 2D, which is closely related to turbulence induced by the mono-pile. It is also found that the presence of the mono-pile might make the flow field more ‘disc-shaped’.
National Key Research and Development Program of China (No.2017YFC1404200), the Marine Renewable Energy Research Project of State Oceanic Administration (No.GHME2015GC01), the Fundamental Research Funds for the Central Universities of China (No.2017B696X14) and the Postgraduate Research & Practice Innovation Program of Jiangsu Province, China (No.KYCX17_0448)
47
Aspinwall, Michael Joseph. « Relating breast-height wood properties to whole-stem wood properties in loblolly pine ». 2007. http://www.lib.ncsu.edu/theses/available/etd-07132007-102928/unrestricted/etd.pdf.
Texte intégral
48
Emebiri, Livinus Chinenye. « Detection and Genetic Mapping of Quantitative Trait Loci Influencing Stem Growth Efficiency in Radiata Pine ». Phd thesis, 1997. http://hdl.handle.net/1885/46845.
Texte intégralRésumé :
Needle-to-stem unit rate (NESTUR) is a stem growth index of conifer seedling trees that measures the efficiency of stemwood production per unit of needle growth. Five experiments were carried out in this thesis using progenies of two unrelated full-sib radiata pine crosses. The initial experiment (experiment 1) applied the bulked segregant analysis technique to determine whether RAPD analysis could be successfully extended to the development of molecular markers for NESTUR in radiata pine. The NESTUR values of 174 progenies of the full-sib family 12038 x 10946 were determined. Based on the genotypic analysis of the individuals, two quantitative trait loci (QTL) controlling NESTUR were identified at ANOVA P-levels of 0.01-0.001. An absence of RAPD fragment markers generated by primers OPE-06 and OPA-10 was associated with low NESTUR values, while primer UBC-333 generated a 550 bp band that was associated with high NESTUR values. Linkage to components of NESTUR (increments in stem diameter and stem volume) was demonstrated for one of the QTL, while the other was unique to NESTUR, and not shared with the components. There was a significant interaction between the two QTLs. Presence of OPA-101200 locus appeared to inhibit expression of the QTL linked to UBC-333 [subscript 550]. ¶ ...
49
Sherrill, Joshua Reid. « Genetic and cultural effects on stem taper and bark thickness in loblolly pine (Pinus taeda L.) ». 2005. http://www.lib.ncsu.edu/theses/available/etd-03222005-151742/unrestricted/etd.pdf.
Texte intégral
50
Rosier, Christopher L. « Factors affecting the rooting of Fraser fir (Abies fraseri) and Virginia pine (Pinus virginiana) stem cuttings ». 2003. http://www.lib.ncsu.edu/theses/available/etd-04292003-110435/unrestricted/etd.pdf.
Texte intégral