Дисертації з теми "Compressor stem"
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1
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.
Повний текст джерела
2
Дережук, Михайло Васльович. "Відновлення штоку гідроциліндру плазмовим напиленням". Master's thesis, КПІ ім. Ігоря Сікорського, 2018. https://ela.kpi.ua/handle/123456789/28500.
Повний текст джерелаАнотація:
В даному дипломному проекті розглядається питання пов’язане з підвищенням зносостійкості штоку гідроциліндра плазмовим напиленням.
Проведено аналіз умов роботи та експлуатації штоку гідроциліндра, досліджено технологічні характеристики основного та матеріалу для напилення.
Розроблено технологію підвищення зносостійкості, яка забезпечує якісне формування напиленого шару та високі зносостійкі властивості.
В розділі з охорони праці висвітлено питання підвищення електробезпеки, газової безпеки та покращення умов праці персоналу.
Записка вміщує 93 сторінки машинописного тексту, 24 рисунків, 23 таблиць, 1 додаток, 15 джерел літератури.In this thesis project the issue related to increase wear resistance of hydraulic cylinder with plasma spraying is indicated. The analysis of the working conditions and the operating of compressor stem has been studied. The technological characteristics of the basic and surfacing materials have been investigated. The technology of restoration that ensures a high-quality formation of the deposited layer, providing the high wear resistant properties, has been developed. In the section on Occupational Health and Safety the issues of enhance electrical and gas safety and improvement of the working conditions of the personnel are highlighted. The note contains 93 pages of typewritten text, 8 figures, 10 tables, 2 appendixes, 15 sources of literature.
3
Hedges, Collin R. "Computational fluid dynamic model of steam ingestion into a transonic compressor." Thesis, Monterey, Calif. : Naval Postgraduate School, 2009. http://edocs.nps.edu/npspubs/scholarly/theses/2009/Jun/09Jun%5FHedges.pdf.
Повний текст джерелаАнотація:
Thesis (M.S. in Mechanical Engiineering)--Naval Postgraduate School, June 2009.Thesis Advisor(s): Gannon, Anthony J. "June 2009." Author(s) subject terms: Computational Fluid Dynamics, Transonic, Compressor, Steam Ingestion, Sanger Rotor. Description based on title screen as viewed on July 10, 2009. Includes bibliographical references (p. 61). Also available in print.
4
Levis, William R. "Unsteady casewall pressure measurements in a transonic compressor during steam induced stall." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2006. http://library.nps.navy.mil/uhtbin/hyperion/06Jun%5FLevis.pdf.
Повний текст джерела
5
Ho, Fu-chak, and 何富澤. "Effect of cyclic compression on cytoskeleton remodeling and cell matrix interaction of hMSCs encapsulated in three dimensional type I collagen matrix." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2014. http://hdl.handle.net/10722/197108.
Повний текст джерелаАнотація:
The potential of determining stem cell fate through mechanoregulation has been demonstrated recently. However, the underlying mechanism remains largely unknown. Previously, we developed a novel microencapsulation technique to entrap cells in a nanofibrous collagen meshwork and use the cell-collagen model to study mechanoregulation of human mesenchymal stem cells (hMSCs). Initially, hMSCs were randomly distributed within the construct. Upon cyclic compression, hMSCs reoriented towards a direction along the loading axis. Cytoskeleton, being the major sub-cellular machinery supporting cell shape and motility, should play crucial role in sensing and responding mechanical signals. Therefore, a better understanding in the change of cytoskeleton and associated molecules upon mechanical loading is a prerequisite to rationalizing the loading regimes for stem cell-based functional tissue engineering.
In the current project, we hypothesize that hMSCs encapsulated in 3D collagen construct will respond to cyclic compression by remodeling the cytoskeleton structures and altering the interactions with collagen matrix. hMSCs collagen construct were cyclically compressed for 9 hours through micromanipulator based compression system. After compression, constructs were harvested either immediately after compression, 2 hours after compression and 24 hours compression, together with non-loading control group.
Here, we report compression-induced novel changes in cytoskeleton. Firstly, omnidirectional filopodia-like structures together with stress fibers bucking were observed immediately after 9hrs of cyclic compression. Secondly, actin patches were observed shortly after removal of 9hrs compression before the actin fibers resumed. Apart from exhibiting similar morphology with filopodia, the omnidirectional filopodia-like structures may share a similar function in interacting with ECM. Co-localization of the major membrane-bound matrix metalloproteinases MT1-MMP with actin staining was found along the length of the filopodia-like structures. A local collagen digestion zone, characterized by the presence of collagenase cleaved collage, was found co-localizing at least partially with the filopodia-like structures around the cell. Whether creating pericellular collagen digestion zone was mediated by MT1-MMP along the compression-induced filopodia like structures and what functions the digestion zone serves are interesting question to answer in the future.
Another interesting observation is the complete disassembly of pre-existing stress fibers followed by formation by numerous actin patches throughout the cell shortly after removal of the compression loading. Stress fibers reformed in 24 hours after removal of the loading. Quantitative measurement of F:G actin ratio agrees with such disassembly and reassembly dynamics. Colocalization of actin branching protein arp2/3 with the actin patches was found, suggesting that mechanically loaded hMSCs were re-establishing actin cytoskeleton network from these nucleation centers. Further studies are required to figure out the underlying significance of the loading-induced cytoskeleton dynamics in hMSCs and whether the actin patches Arp2/3 complex associates with endocytosis of cleaved collagen fragments.published_or_final_version
Mechanical Engineering
Doctoral
Doctor of Philosophy
6
Villescas, Ivan J. "Flow field surveys in a transonic compressor prior to inlet steam ingestion tests." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2005. http://library.nps.navy.mil/uhtbin/hyperion/05Sep%5FVillescas.pdf.
Повний текст джерелаАнотація:
Thesis (M.S. in Mechanical Engineering)--Naval Postgraduate School, September 2005.Thesis Advisor(s): Garth Hobson, Anthony Gannon. Includes bibliographical references (p. 57-59). Also available online.
7
Hurley, Andrew M. "Experimental investigation of high-pressure steam-induced surge in a transonic compressor stage." Thesis, Monterey, Calif. : Naval Postgraduate School, 2008. http://bosun.nps.edu/uhtbin/hyperion-image.exe/08Jun%5FHurley.pdf.
Повний текст джерелаАнотація:
Thesis (M.S. in Mechanical Engineering)--Naval Postgraduate School, June 2008.Thesis Advisor(s): Gannon, Anthony J. "June 2008." Description based on title screen as viewed on August 25, 2008. Includes bibliographical references (p. 29-30). Also available in print.
8
Li, Chuen-wai, and 李鑽偉. "Dynamic compression and exogenous fibronectin regulates cell-matrix adhesions and intracellular signaling proteins of human mesenchymal stem cells in 3D collagen environment." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hdl.handle.net/10722/197553.
Повний текст джерелаАнотація:
The fundamental principle of tissue engineering is to use appropriate cell source, combined with scaffolds and bioactive factors to develop tissue constructs which restore, maintain or improve tissue function. There is increasing data emphasizing the importance of mechanical signals and extracellular matrix (ECM) proteins presented by the scaffold in determining stem cell fate/functions which are critical to tissue construct maturation and success of stem cell-based therapies. Cell-matrix adhesions are one of the major mechanosensing machineries cells use to convert information provided by ECM ligands and mechanical signals presented by scaffolds into intracellular biochemical signaling cascades which lead to particular functional responses. Therefore, understanding how ECM ligands and mechanical signals regulate cell-matrix adhesion formation and activation of associated intracellular signaling proteins is fundamental to rational design of biomaterial and loading protocol for optimal cell functional responses in tissue constructs.
In this study, we attempted to understand the regulatory effects of external mechanical signal and exogenous ECM protein on cell-matrix adhesion formation and associated intracellular signaling proteins of human mesenhymal stem cells, and in particular, to test the hypothesis that mechanical stimulation or exogenous ECM protein can lead to adhesion maturation into 3D-matrix adhesions in 3D collagen environment. We used microencapsulation technique to embed cells in 3D collagen environment, forming disc-shaped hMSC-collagen constructs. By immunofluorescent staining and confocal microscopy, we visualized changes in size, morphologies and molecular composition of the adhesions.
First of all, 2D adhesions of hMSCs were characterized. We showed that hMSCs form well-organized αv integrin-based focal adhesions and fibrillar adhesions in 2D culture. To investigate the regulatory effects of mechanical signals on adhesion signaling and maturation, we used micromanipulator-based loading device to impose dynamic compression to hMSC-collagen constructs. We found that dynamic compression lead to enlargement of integrin αv adhesions which recruit focal adhesion kinase (FAK), vinculin and extracellular signal-regulated kinase (ERK). In addition, FAK was activated at enlarged integrin αv adhesions and translocated to peri-nuclear region after compression, suggesting that loading induces activation of FAK signaling pathways through increased integrin αv clustering. Moreover, we demonstrated that dynamic compression can induce 3D-matrix adhesion formation, indicating the role of external force in integrin α5-based adhesion maturation in 3D collagen environment.
We explored the effect of exogenous ECM proteins on adhesion maturation of hMSCs by adding fibronectin into cell-collagen mixture during fabrication of collagen constructs. Our results demonstrated that the exogenous fibronectin can induce α5 integrin-based adhesion maturation into 3D-matrix adhesions in our collagen constructs in a dose-dependent manner.
This study demonstrated that the effect of external mechanical signals and exogenous ECM ligands on adhesion signaling and maturation of hMSCs in 3D collagen environment. Our findings contribute towards mechanobiology of hMSCs in 3D context. In particular, our results showed that exogenous proteins or external loading can lead to 3D-matrix adhesion formation, which may serve as a potential way to enhance biological functions of hMSCs in collagen constructs, facilitating stem cell-based therapies.published_or_final_version
Mechanical Engineering
Doctoral
Doctor of Philosophy
9
Payne, Thomas A. "Inlet flow-field measurements of a transonic compressor rotor prior to and during steam-induced rotating stall." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2005. http://library.nps.navy.mil/uhtbin/hyperion/05Dec%5FPayne.pdf.
Повний текст джерела
10
Zarro, Sarah E. "Steady state and transient measurements within a compressor rotor during steam-induced stall at transonic operational speeds." Thesis, Monterey, California. Naval Postgraduate School, 2006. http://hdl.handle.net/10945/2528.
Повний текст джерелаАнотація:
Approved for public release, distribution unlimitedSteam leakage from an aircraft carrier catapult is sometimes ingested into the aircraft engines upon launch which may induce compressor stall. Investigation of this phenomenon is of particular interest to the Navy with its new F35C, the aircraft carrier variant of the joint strike fighter. The single engine configuration of the F-35C makes this aircraft particularly vunerable to steam-induced stall. The present study examined both throttle-induced stall and steam-induced stall in a compressor at 90% and 95% speed through the use of 9 Kulite and 2 hot-film pressure transducers. The use of Fast Fourier Transform waterfall plots of the transient data before and during stall proved invaluable in determining stall precursors as well as the mode of rotor stall. In addition, a new computational fluid dynamic model was designed using CFX-5 software to represent a single blade passage of the compressor rotor, in order to predict compressor performance. The computed results were compared to experimental results gathered at various throttle settings. An accurate model will enable researchers to predict compressor performance for various and multiple gases.
Outstanding Thesis
11
Phaiboonsilpa, Natthanon. "CHEMICAL CONVERSION OF LIGNOCELLULOSICS AS TREATED BY TWO-STEP SEMI-FLOW HOT-COMPRESSED WATER." Kyoto University, 2010. http://hdl.handle.net/2433/126764.
Повний текст джерела
12
Мірошниченко, Володимир Валерійович, Владимир Валерьевич Мирошниченко, Volodymyr Valeriiovych Miroshnychenko, В`ячеслав Михайлович Арсеньєв, Вячеслав Михайлович Арсеньев та Viacheslav Mykhailovych Arseniev. "Струйная термокомпрессорная установка для когенерационных энергопреобразующих систем". Thesis, Сумский государственный университет, 2016. http://essuir.sumdu.edu.ua/handle/123456789/45736.
Повний текст джерелаАнотація:
В условиях непрерывного роста цен на энергоносители, предельного
состояния износа оборудования тепловых электростанций и высокого уровня
энергозатратности экономики Украины, в значительной степени зависящей
от условий импорта нефти и природного газа, все более актуальным
становится применение малых энергогенерирующих систем непосредственно
у потребителей. Теоретические ресурсы потенциальной энергии, которая
теряется при дросселировании природного газа на ГРС и ГРП в Украине
составляют около 5 млн. МВт·ч ежегодно.
13
Kohut, Vojtěch. "Výroba stlačeného vzduchu v TŽ Třinec." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2011. http://www.nusl.cz/ntk/nusl-229816.
Повний текст джерелаАнотація:
The main purpose of this master’s thesis is description of the current technology of compressed air production in the grounds of Třinecké Železárny, a.s. (TZ). Compressed air for companies in the TZ area is manufactured and distributed by company Energetika Třinec, a.s. (ET). The part of the thesis is the preparation and execution of measurement including evaluation of specific energy consumption for production of compressed air by compressors of ET company. In conclusion there is proposed the possibility of substitution of compressors including the economic evaluation.
14
ALBUQUERQUE, Carlos Eduardo da Silva. "Avaliação do comportamento energético e exergético de um sistema de refrigeração por compressão de vapor." Universidade Federal de Campina Grande, 2017. http://dspace.sti.ufcg.edu.br:8080/jspui/handle/riufcg/1249.
Повний текст джерелаАнотація:
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CNPq
Esta pesquisa apresenta uma análise energética e exergética de uma unidade de refrigeração de água gelada de grande porte, chamada chiller. O refrigerador em estudo realiza o ciclo termodinâmico de refrigeração com auxílio de um compressor mecânico, usualmente acionado por um motor elétrico, de forma a aumentar a pressão em determinada fase do ciclo termodinâmico do sistema, o que gera um alto consumo de energia elétrica. Com avanço da tecnologia, a cada dia surgem novos tipos de compressores que possuem um menor consumo de energia e melhoram o desempenho da unidade como um todo. O objetivo deste trabalho é avaliar os comportamentos energético e exergético, baseados respectivamente na primeira lei e na segunda lei da termodinâmica, de um chiller que fornece água gelada e trabalha com um compressor tipo parafuso. Este estudo foi realizado baseando-se no comportamento real de um chiller de compressão de vapor, instalado em um shopping da região de João Pessoa-PB. Através de simulação numérica, foi possível avaliar o comportamento do equipamento com a mudança de alguns dos parâmetros normais de trabalho, como pressões de condensação e evaporação, temperatura s de condensação e evaporação e fluido refrigerante. Neste estudo, são apresentados dados do desempenho do equipamento em função das pressões do evaporador e do compressor, da temperatura de evaporação, entre outros parâmetros. Os resultados das simulações, realizadas com auxilio do software EES, mostraram que o desempenho da unidade melhora ao diminuir a variação de pressão entre o condensador e o evaporador e que as eficiências energética e exergética sofrem um acréscimo com o aumento da temperatura de evaporação e uma redução com a elevação da temperatura de condensação.
This research presents energetic and exergetic analysis of a water refrigeration unit, called Chiller. The Chiller under study performs the thermodynamic cycle of the refrigeration with the assistance of a mechanical compressor, usually triggered by an electric motor, in order to increase the pressure in a certain stage on the thermodynamic cycle of the system, which generates high energy consumption. However, with the advance of the technology, every day emergs new types of compressors that have lowest energy consumption and improves the performance of the unit as a whole. The purpose of this work is to evaluate both e nergetic and exergetic behavior, of a chiller that provides cold water and works with a screw type compressor, based on the first and second laws of thermodynamics . This study was based on the actual behavior of a steam compression chiller from a mall in the city of João Pessoa-PB. Through numerical simulation, it was possible to evaluate the behavior of the equipment with the change of some of the normal parameters of work, as condensation and evaporation pressures, condensation and evaporation temperature and refrigerant fluid. In this study, the performance of the equipment data is presented as a function of the evaporator and compressor pressures, the evaporation temperature and other parameters. The results of the simulations, that were realized with support of software EES, showed that the unit performance was improved by decreasing the pressure variation between condenser and the evaporator and also has proved that the energetic and exergetic efficiences are increased by raising the evaporation temperature and a reduction happens by increasing the condensation temperature.
15
Fritz, Jason Ronald. "The Chondrogenesis of PDLs by Dynamic Unconfined Compression Is Dependent on p42/44 and Not p38 or JNK." Scholarly Repository, 2009. http://scholarlyrepository.miami.edu/oa_theses/225.
Повний текст джерелаАнотація:
Articular cartilage lines the surfaces of load bearing joints and has limited capabilities for self-repair due to its alymphatic and avascular structure. Attempts at making repairs to this tissue has resulted in substandard materials and/or causing further injury to the patient making this tissue a prime candidate for tissue engineering studies incorporating adult stem cells. These studies have given rise to some answers and many more questions including a search for alternative stem cell sources and what biochemical changes the cells undergo during the differentiation of these stem cells into chondrocytes, the cells which make up articular cartilage. Recently, periodontal dental ligament stem cells (PDLs) have come to the forefront as a practical alternative to other adult stem cells as well as the involvement of the mitogen-activated protein kinases (MAPKs) in stem cell differentiation via mechanical stimulation. During dynamic unconfined compression, levels of p42/44 MAPK increased by 50% (p<0.05). Additionally, the expression of the chondrogenic differentiation factor SRY (sex determining region Y)-box 9 (SOX-9) increased by 3-fold (p<0.05) as well as the chondrocyte marker aggrecan by over 2-fold after 4h of dynamic unconfined compression. Addition of the p42/44 phosphorylation inhibitor PD98059, along with compression, yielded no change in SOX-9 or aggrecan expression levels from basal levels in uncompressed controls. Inhibition of p38 MAPK or JNK phosphorylation during unconfined compression had no effect on the elevated expression of SOX-9 and aggrecan as compared to compressed cells without the addition of an inhibitor. It is therefore the overall findings of this study that PDLs possess the ability to differentiate into chondrocytes by mechanical compression and this differentiation is mediated by the p42/44 MAPK cascade.
16
Tegas, Antonio Vasile. "Finite element modeling of flow/compression-induced deformation of alginate scaffolds for bone tissue engineering." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amslaurea.unibo.it/10209/.
Повний текст джерелаАнотація:
Trauma or degenerative diseases such as osteonecrosis may determine bone loss whose recover is promised by a "tissue engineering“ approach. This strategy involves the use of stem cells, grown onboard of adequate biocompatible/bioreabsorbable hosting templates (usually defined as scaffolds) and cultured in specific dynamic environments afforded by differentiation-inducing actuators (usually defined as bioreactors) to produce implantable tissue constructs.
The purpose of this thesis is to evaluate, by finite element modeling of flow/compression-induced deformation, alginate scaffolds intended for bone tissue engineering.
This work was conducted at the Biomechanics Laboratory of the Institute of Biomedical and Neural Engineering of the Reykjavik University of Iceland.
In this respect, Comsol Multiphysics 5.1 simulations were carried out to approximate the loads over alginate 3D matrices under perfusion, compression and perfusion+compression, when varyingalginate pore size and flow/compression regimen.
The results of the simulations show that the shear forces in the matrix of the scaffold increase coherently with the increase in flow and load, and decrease with the increase of the pore size.
Flow and load rates suggested for proper osteogenic cell differentiation are reported.
17
Кухарев, И. Е., та В. И. Гецман. "Повышение надежности турбины Р-32 компрессора синтез-газа поз. 401 на предприятии ОАО "Минудобрения", г. Россошь". Thesis, Издательство СумГУ, 2011. http://essuir.sumdu.edu.ua/handle/123456789/21540.
Повний текст джерелаАнотація:
Описывается модернизация паровой турбины привода компрессора синтез – газа производства аммиака, выполненная фирмой ООО «ТРИЗ» с целью снижения уровней вибраций во всем диапазоне частот вращения ротора турбины за счет уменьшения расстояния между подшипниками и установки дополнительной демпферной опоры.
При цитуванні документа, використовуйте посилання http://essuir.sumdu.edu.ua/handle/123456789/21540There described modernizing the steam turbine for driving the synthesis – gas compressor of ammonia production, which has been executed by the TRIZ OOO to decrease the vibration levels throughout the rotational speed range of the turbine rotor at the expense of decreasing the distance between the bearings and installing additional damping support При цитировании документа, используйте ссылку http://essuir.sumdu.edu.ua/handle/123456789/21540
18
Mesnard, Philippe. "Formes d’onde à saut de fréquences et Compressed Sensing : Application à la détection et à la reconnaissance aéroportées." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLG004.
Повний текст джерелаАнотація:
Les changements dans le contexte du traitement radar aéroporté impliquent de plus en plus d'améliorations qui justifient la recherche d'une alternative au filtrage adapté, qui est le processus utilisé classiquement pour estimer les paramètres des cibles détectées. Le Compressed Sensing ouvre la perspective d'un nouveau traitement, également efficace dans les configurations de cibles multiples, avec de meilleures performances de suivi et de reconnaissance que l'approche classique. Nous cherchons à appliquer ce traitement aux formes d'onde dites à évasion de fréquence. Le choix intégral des paramètres de définition du signal transmis déterminee entièrement la matrice de mesure de la procédure du Compressed Sensing, laquelle solution fournit toutes les informations recherchées sur la scène observée. Pour chaque signal à évasion de fréquence, et d'amplitude constante, la matrice de mesure correspondante est obtenue en extrayant certaines lignes d'une matrice de Fourier étendue particulière, la matrice de Fourier 2D. La construction de la génération de la matrice de mesure est importante car le succès de la reconstruction dépend des propriétés algébriques de cette matriceChanges in the context of airborne radar processing implie more and more improvements that justify to look for an alternative to Matched Filtering, the process conventionally used to estimate the parameters of detected targets. Compressed Sensing suggests a new treatment, also performing in multi-target cases, with better tracking and recognition performances than classical approach. We seek to apply this treatment to step frequency waveforms. The whole choice of definition parameters for the transmitted signal entirely builds the measurement matrix of the Compressed Sensing procedure which solution gives all the sought information of the observed scene. For each step frequency signal with constant amplitude, the resulting measurement matrix is obtained by extracting some lines from a particular extended Fourier matrix, the 2D Fourier matrix. The construction of the measurement matrix generation is important since the success of the reconstruction depends on the algebraic properties of this matrix
19
Прокопов, Максим Геннадійович, Максим Геннадьевич Прокопов та Maksym Hennadiiovych Prokopov. "Теплофизическое моделирование рабочего процесса жидкостно-парового струйного компрессора". Thesis, Изд-во СумГУ, 2011. http://essuir.sumdu.edu.ua/handle/123456789/23679.
Повний текст джерелаАнотація:
У дисертаційній роботі наведені: теплофізична модель рідинно-
парового струминного компресора, результати аналізу
експериментальних досліджень закипаючих потоків рідини у каналах,
що розширюються, і проточній частині рідинний-парового
струминного компресора, опис формування трьох критичних режимів
течії і структурної інверсії потоку, характеристики компресора.
Представлена математична модель робочого процесу, яка
дозволяє визначати параметри і характеристики рідинно-парового
струминного компресора. Створена методика інженерного розрахунку
реалізована у вигляді розрахункової програми для ЕОМ і дозволяє
створити компресор з високими показниками ефективності.
При цитуванні документа, використовуйте посилання http://essuir.sumdu.edu.ua/handle/123456789/23679В диссертационной работе приведены: теплофизическая модель жидкостно-парового струйного компрессора, результаты анализа экспериментальных исследований вскипающих потоков жидкости в расширяющихся каналах и проточной части жидкостно-парового струйного компрессора, описание формирования трех критических режимов течения и структурной инверсии потока, характеристики компрессора. Представлена математическая модель рабочего процесса, которая позволяет определять параметры и характеристики жидкостно-парового струйного компрессора. Созданная методика инженерного расчета реализована в виде расчетной программы для ЭВМ и позволяет создать компрессор с высокими показателями эффективности. При цитировании документа, используйте ссылку http://essuir.sumdu.edu.ua/handle/123456789/23679
The dissertation presents the results: thermophysical model of liquidsteam stream compressor, results of analysis of experimental researches of boiling up streams of liquid in the broadening ductings and running part of liquid-steam stream compressor, description of forming of three critical modes of flow and structural inversion of stream. The mathematical model of working process, which allows to determine parameters and descriptions of liquid-steam stream compressor, is presented. The created method of engineering calculation is realized as a calculation program for computer and allows to create a compressor highperformance efficiency, descriptions of compressor. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/23679
20
Sendeski, Mauricio Michalak. "Atividade simpática na hipertensão arterial associada à compressão neurovascular do bulbo rostral ventro-lateral em humanos." Universidade de São Paulo, 2004. http://www.teses.usp.br/teses/disponiveis/5/5160/tde-14102014-092123/.
Повний текст джерелаАнотація:
Introdução: A prevalência de perda auditiva em recém-nascidos (RN) normais e lactentes é estimada em 1,5 a 6/1.000 nascidos vivos, sendo que naqueles considerados de alto risco varia de 1,5 a 17%. Objetivos: Verificar a prevalência de deficiência auditiva adquirida em RN e lactentes que ficaram internados em unidade de cuidados intensivos (UTI) e intermediários; relacionar a deficiência auditiva com a existência de fatores de risco para este evento e determinar o nível anatômico da lesão nos RN que apresentarem esta deficiência. Métodos: Estudo de coorte prospectivo no período de setembro de 2003 a março de 2004, com 71 recém-nascidos de três Hospitais da cidade de São Paulo, com populações de características semelhantes. Em relação ao sexo, 26 (36,62%) eram do sexo feminino e 45 (63,38%) do masculino; a média de peso e idade gestacional ao nascimento foi 2.480,63g (825g-4215g) e 36,14 semanas (25,57 - 41,57 semanas), respectivamente. Os 71 RN realizaram a primeira avaliação auditiva utilizando o método de emissão otoacústica evocada transiente (EOAET) aplicado durante a internação hospitalar. A segunda avaliação foi ambulatorial e além de o método de EOAET foi aplicado também o de audiometria de tronco cerebral (ABR). A média de idade cronológica e idade gestacional corrigida na primeira avaliação auditiva foi 19,36 dias e 38,86 semanas, enquanto na segunda avaliação foi 73,50 dias e 46,61 semanas, respectivamente. Os fatores de risco escolhidos para testar uma possível relação com deficiência auditiva foram: perinatais, respiratórios, infecciosos, metabólicos, uso de equipamentos e outros, como: tempo de ventilação mecânica, utilização de oxigenioterapia não invasiva, tempo de incubadora e tempo de internação na UTI, fármacos ototóxicos, neurológicos, insuficiência renal e retinopatia da prematuridade. Os dados foram avaliados descritivamente pelo cálculo de médias e proporções, análise inferencial e teste de concordância entre a primeira e segunda avaliação audiológica. Resultados: Dos 71 RN avaliados, 23 (32,39%) apresentaram alteração auditiva, sendo 8 (30,77%) do sexo feminino e 15 (33,33%) do masculino. Em relação à lateralidade, 11 (47,83%) RN apresentaram alterações unilaterais e 12 (52,17%) bilaterais e em relação ao local da lesão, 14 (60,87%) apresentaram alterações cocleares, 1 (4,35%) retrococlear e 8 (34,78%) mista. A alteração auditiva esteve estatisticamente associada com: RN pequeno para a idade gestacional, apnéia, hipocalcemia, uso de dois ou mais fármacos ototóxicos, amicacina e furosemida Houve fraca concordância entre as duas avaliações realizadas com EOAET (k=0,138, intervalo de confiança (95%)=[0; 0,364]). Conclusões: a prevalência de perda auditiva nos RN e lactentes internados nas unidades de cuidados intensivos e intermediários foi mais elevada do que a da citada na literatura. Houve associação estatística com seis fatores de risco estudados e não houve diferença entre o comprometimento unilateral e bilateral, com predomínio da freqüência de alterações cocleares, seguidas de alterações mistas e retrococlearesIntrodution: The prevalence of newborn and infant hearing loss is estimated to range 1.5 to 6 per 1.000 live births and newborn with risk factors for hearing loss range 1.5 to 17%. Objective: To verify the prevalence of newborns and infants hearing loss admitted in the intensive and intermediary care unit; to relate the hearing loss with the presence of risk factors for such event and to determine the wound anatomic level. Methods: It is a prospective cohort study with 71 newborns (NB), in three Hospitals in São Paulo (September 2003 and March 2004). Twenty six (36.62%) NB females and 45 (63.38%) males. The average of the weight and of the gestational age at the birth were 2,480.63 g (825 g-4,215 g) and 36.14 weeks (25.57-41.57 weeks), respectively. The first evaluation using the transient evoked otoacoustic emission during the hospitalization. The second was performed in the ambulatory of the hospital with transient evoked otoacoustic emission and auditory brainstem response. The average of the chronologic age and of the gestacional age at the first evaluation were 19.36 days and 38.86 weeks and at the second evaluation were 73.50 days and 46.61 weeks, respectively. The risk factors for hearing loss evaluated: perinatal, respiratory, infection, metabolic, use of equipment and others (mechanical ventilation duration, use of non-invasive oxygen-therapy, time in the incubator and neonatal in the intensive unit care), ototoxic medications, neurological, renal ins ufficiency and retinopathy of prematurity. The data were evaluated calculating averages and proportions, inferential analysis and concordance test between the first and the second audiologic evaluation. Results: Twenty three (32.39%) NB of the 71 presented a hearing loss, eight (30.77%) females and 15 (33.33%) males. Eleven (47.83%) newborns presented unilateral alteration and 12 (52.17%) bilateral. Fourteen NB (60.87%) presented cochlear alteration, 1 (4.35%) retrocochlear and 8 (34.78%) mixed. The hearing loss was significantly associated with small for gestational age newborns; apnea, hypocalcaemia, administration ototoxic medications, administration of amicacine and furosemida. The concordance test between the first and the second transient evoked otoacoustic emission was weak (k=0.138, 95%confidence interval 0;0.364). Conclusions: The prevalence of hearing loss in this study was high that in the literature. The hearing loss was significantly associated with six risks factors studied. The difference between unilateral and bilateral alteration wasn\'t observed, the cochlear alteration was more frequent, following the mixed and retrocochlear alteration
21
Fourie, Neil. "Simulating the effect of wind on the performance of axial flow fans in air-cooled steam condenser systems." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/95977.
Повний текст джерелаАнотація:
Thesis (MEng) -- Stellenbosch University, 2014.ENGLISH ABSTRACT: The use of air-cooled steam condensers (ACSCs) is the preferred cooling method in the chemical and power industry due to stringent environmental and water use regulations. The performance of ACSCs is however highly dependent on the influence of windy conditions. Research has shown that the presence of wind reduces the performance of ACSCs. It has been found that cross-winds (wind perpendicular to the longest side of the ACSC) cause distorted inlet flow conditions, particularly at the upstream peripheral fans near the symmetry plane of the ACSC. These fans are subjected to what is referred to as '2-D' wind conditions, which are characterised by flow separation on the upstream edge of the fan inlets. Experimental investigations into inlet flow distortion have simulated these conditions by varying the fan platform height. Low platform heights resulted in higher levels of inlet flow distortion, as also found to exist with high cross-wind speeds. This investigation determines the performance of various fan configurations (representative of configurations used in the South- African power industry) subjected to distorted inlet flow conditions through experimental and numerical investigations. The similarity between platform height and cross-wind effects is also investigated and a correlation between system volumetric effectiveness, platform height and cross-wind velocity is found.
AFRIKAANSE OPSOMMING: Die gebruik van lugverkoelde stoom kondensors (LVSK's) word verkies as 'n verkoelingsmetode in die chemiese- en kragvoorsieningsindustrie as gevolg van streng omgewings- en waterverbruiksregulasies. Die werkverrigting van LVSK's word egter grootliks beïnvloed deur die teenwoordigheid van wind. Navorsing het gewys dat die teenwoordigheid van wind die werkverrigting van LVSK's verminder. Daar was gevind dat kruiswinde (wind loodreg tot die langste sy van die LVSK) versteurde inlaat vloeitoestande veroorsaak, veral by waaiers wat aan die stroomop kant van die LVSK naby die simmetrievlak geleë is. Hierdie waaiers word blootgestel aan na wat verwys word as '2-D' windtoestande wat gekenmerk word deur vloeiwegbreking wat plaasvind by die stroomop rand van die waaierinlate. Eksperimentele ondersoeke van inlaat vloeiversteurings het hierdie toestande gesimuleer deur die waaier platformhoogte te verstel. Lae platform hoogtes het gelei tot hoër vlakke van inlaat vloeiversteuring, soortgelyk aan wat gevind word met hoë kruiswindsnelhede. Hierdie ondersoek gebruik numeriese en eksperimentele metodes om die werkverrigting van verskeie waaierkon gurasies (verteenwoordigend van kon- gurasies wat gebruik word in die Suid-Afrikaanse kragvoorsieningsindustrie) wat blootgestel word aan versteurde inlaat vloeitoestande te bepaal. Die ooreenkoms tussen platformhoogte en kruiswind e ekte word ook ondersoek en 'n korrelasie tussen die sisteem volumetriese e ektiwiteit, platformhoogte en kruiswindsnelheid word bepaal.
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Votoupal, Adam. "Parní protitlaková turbína s integrovanou převodovkou pro pohon kompresoru." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-400498.
Повний текст джерелаАнотація:
The master’s thesis deals with the design of steam back-pressure turbine with integrated gearbox for compressor drive according to given parameters. The first part of the thesis is literature review which comprises a general division of steam turbines, especially a description of the types of blading. Furthermore, it describes the conversion of energy in the steam turbine stage in detail. The second part of the thesis contains calculations and includes the design of the flow parts of the steam turbine, the design of the outlet and the integrated gearbox. Attached to this work are drawings of a simplified section of the steam turbine with a gearbox and the layout drawing of the machine.
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Козін, Віктор Миколайович, Виктор Николаевич Козин, Viktor Mykolaiovych Kozin та М. В. Заставенко. "Аналіз ефективності роботи конденсатора повітряного охолодження парокомпресійної холодильної машини". Thesis, Сумський державний університет, 2017. http://essuir.sumdu.edu.ua/handle/123456789/62418.
Повний текст джерелаАнотація:
З часом резерви розвіданих первинних ресурсів вичерпуються,
кількість нафти і природного газу, з розумною ціною видобування, з кожним
роком стає менше, а попит на них зростає. Крім того, останнім часом
спостерігається загальна тенденція стрімкого подорожчання первинних
енергоресурсів, що у свою чергу призводить до зростання цін на кінцевий
продукт. Очевидно, що економія первинних енергоресурсів є невід’ємною
складовою будь-якого підприємства, зокрема пов’язаного із використанням
холодильної техніки.
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Головань, С. В. "Теплонасосна установка з використанням пароструминної термокомпресії". Master's thesis, Сумський державний університет, 2019. http://essuir.sumdu.edu.ua/handle/123456789/76512.
Повний текст джерелаАнотація:
У роботі розглянуто схеми та принципи дії тепловикористовуючих теплових насосів, до яких відносяться абсорбційні, адсорбційні та пароежекторні насоси.
Також виконано термодинамічний аналіз пароструминного термотрансформатора, який працює в режимі теплового насоса.
У дослідній частині поставлені задачі дослідження, розроблено теплонасосну установку з використанням пароструминної термокомпресії та досліджено зміни температури випаровування холодильного агента та температури на вході до паронагрівача на ефективність її роботи.
У конструкторській частині виконано тепловий конструктивний розрахунок пароструминного ежектора.
В розділі охорони праці розглянуто техніку безпеки при експлуатації холодильного виробництва, проведено Аналіз шкідливих та небезпечних факторів холодильного виробництва, виконано розрахунок природного та штучного освітлення.В работе рассмотрены схемы и принципы действия теплоиспользующих тепловых насосов, к которым относятся абсорбционные, адсорбционные и пароэжекторные насосы. Также выполнен термодинамический анализ пароструйного термотрансформатора, который работает в режиме теплового насоса. В исследовательской части поставленные задачи исследования, разработана теплонасосной установки с использованием пароструйных термокомпрессии и исследованы изменения температуры испарения холодильного агента и температуры на входе в паронагревателя на эффективность ее работы. В конструкторской части выполнен тепловой конструктивный расчет пароструйного эжектора. В разделе охраны труда рассмотрены технике безопасности при эксплуатации холодильного производства, проведения Анализ вредных и опасных факторов холодильного производства, произведен расчет естественного и искусственного освещения.
The work discusses the schemes and principles of operation of heat-using heat pumps, which include absorption, adsorption and steam jet pumps. A thermodynamic analysis of the steam-jet thermotransformer, which operates in the heat pump mode, was also performed. In the research part, the objectives of the study were developed, a heat pump installation using steam-jet thermal compression was developed, and changes in the temperature of evaporation of the refrigerant and the temperature at the inlet of the steam heater on its efficiency were studied. In the design part, the thermal design calculation of the steam-jet ejector was performed. In the section of labor protection, safety measures are considered during operation of the refrigeration industry, analysis of harmful and dangerous factors in the refrigeration industry, calculation of natural and artificial lighting.
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Warensjö, Mats. "Compression wood in Scots pine and Norway spruce : distribution in relation to external geometry and the impact on dimensional stability in sawn wood /." Umeå : Swedish University of Agricultural Sciences, 2003. http://diss-epsilon.slu.se/archive/00000415/.
Повний текст джерелаАнотація:
Thesis (doctoral)--Swedish University of Agricultural Sciences, 2003.Thesis documentation sheet inserted. Appendix includes reprints of five papers and manuscripts, four co-authored with others. Includes bibliographical references. Also issued electronically via World Wide Web in PDF format; online version lacks appendix.
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Moraes, Mayara Queiroz. "Contribuição aos estudos da influência da nanossílica nas propriedades mecânicas e na trabalhabilidade de concretos para produção em centrais e para fabricação de pré-moldados." Universidade Federal de Goiás, 2012. http://repositorio.bc.ufg.br/tede/handle/tede/3429.
Повний текст джерелаАнотація:
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
Unlike the silica fume, whose benefits on the properties of the concretes are already widely known, little is known regarding nanosilica. This research offers an analysis of the contribution of different types of nanosilica in mechanical characteristics and workability maintenance of concretes, as well as an evaluation of the behavior of these additions when subjected to steam curing. For this, there were compared among themselves laboratory test results in concretes with different characteristics and different purposes (one of them suitable for production at batching plants and the other for metering precast elements). The results confirmed advantages for the simple addition of nanossílica at mechanical properties of concretes for batching plants with strengths above 40 MPa (a/c<0.52), but showed that the most advantageous situation consists in adding it together with sílica fume, since the concrete with both additions exceeded the reference concrete above 36 MPa (a/c<0.615), which highlights the importance of combining pozzolanic effect of silica fume, the creation of nucleation sites caused by nanossílica and better packaging mix, size distribution generated by the two additions give the folder.Regarding the maintenance of workability, the nanosilica dispersed in superplasticizer demonstrated satisfactory performance. In the analysis of concretes for precast elements, the addition of nanosilica dispersed superplasticizer and silica fume together was also the one which showed the best results in terms of resistance in 28 days of conventional curing. However, with steam curing, a great improvement was noted in the behavior of nanosilica dispersed in water, which had not achieved good results with the conventional cure, while nanosilica dispersed in superplasticizer did not respond well to the process, possibly due to the shape of the polycarboxylate used in the dispersion of the particles. Probably, the nanosilica dispersed in water showed no significant pozzolanic activity levels, but with the rise of temperature and the agitation of the particles, the formation of nucleation sites was intensified. As the development of resistance in early ages, all additions had positive effects, but the best performance was observed on the concrete with the simple addition of nanosilica dispersed in superplasticizer. With this addition, the concrete has reached 40 MPa after only 12 hours of steam curing, within about four times lower than the reference concrete (44 hours), which suggests that its addition to the concrete could result in na almost four times greater productivity of a precast elements factory.
Ao contrário da sílica ativa, cujas vantagens nas propriedades do concreto já são amplamente conhecidas, pouco se sabe em relação à nanossílica. Esta pesquisa contempla uma análise da contribuição de diferentes tipos de nanossílica nas características mecânicas e de manutenção do abatimento de concretos, bem como uma avaliação do comportamento destas adições frente à cura térmica. Para isto, compararam-se entre si resultados de ensaios laboratoriais em concretos com diferentes traços e diferentes finalidades (produção em centrais dosadoras e fabricação de pré-moldados). Os resultados confirmaram vantagens para a adição simples de nanossílica quanto à resistência à compressão dos concretos para centrais com resistências acima de 40 MPa (a/c<0,52), mas mostraram que a melhor situação consiste na adição conjunta de sílica ativa e nanossílica, já que o concreto com a adição conjunta superou o de referência a partir de 36 MPa (a/c<0,615). Isso deixa clara a importância de aliar o efeito pozolânico da sílica ativa, a criação de pontos de nucleação ocasionada pela nanossílica e o melhor empacotamento da mistura, gerado pela distribuição granulométrica que as duas adições juntas conferem à pasta. Quanto à manutenção do abatimento, a nanossílica dispersa em aditivo superplastificante demonstrou desempenho satisfatório. Em relação aos concretos para pré-moldados, foi a adição conjunta de sílica ativa e nanossílica dispersa em superplastificante a que apresentou melhores resultados de resistência aos 28 dias de cura convencional. No entanto, com a cura térmica, notou-se melhora substancial do comportamento da nanossílica dispersa em água, que não havia atingido bons resultados com cura convencional, enquanto a nanossílica dispersa em superplastificante não respondeu bem ao processo, possivelmente por influência da forma do policarboxilato usado na dispersão das partículas. Provavelmente, a nanossílica dispersa em água não apresentou atividade pozolânica relevante, mas com a elevação da temperatura e a agitação das partículas, a formação de pontos de nucleação foi intensificada. Quanto ao desenvolvimento de resistências nas idades iniciais, todas as adições apresentaram efeitos positivos, mas o melhor desempenho foi observado no concreto com adição simples da nanossílica dispersa em superplastificante. Com ela, o concreto atingiu 40 MPa com apenas 12 horas de cura térmica, prazo quase quatro vezes menor do que o do concreto de referência (44 horas), o que leva a crer que sua adição ao concreto poderia implicar em uma produtividade quase quatro vezes maior de uma fábrica de elementos pré-moldados.
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Лєоньков, Г. А. "Типи холодильних машин". Thesis, Сумський державний університет, 2018. http://essuir.sumdu.edu.ua/handle/123456789/67057.
Повний текст джерелаАнотація:
Холодильні машини є комплексом пристроїв, основною функцією
якого є зменшення та стабілізація зниженої температури, яка є
нижчою за температуру навколишнього середовища в діапазоні від
10°С до -153°С. Холодильні машини є дуже поширеними як у
промисловості, так і в побуті.
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Santos, Liane Ferreira dos [UNESP]. "A influência do patamar de cura térmica sobre a resistência dos concretos auto-adensáveis elaborados com diferentes tipos de cimento: avaliação pelo método da maturidade." Universidade Estadual Paulista (UNESP), 2010. http://hdl.handle.net/11449/94478.
Повний текст джерелаАнотація:
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santos_lf_me_ilha.pdf: 6137370 bytes, checksum: 5de758f11cce6406d87fe87638a96bb5 (MD5)O concreto auto-adensável (CAA) é um material que representa um dos maiores avanços na tecnologia do concreto das últimas décadas. O desenvolvimento do CAA propiciou eficiência e melhora nas condições de trabalho em canteiro de obras e na indústria de pré-moldados. Do ponto de vista reológico, o CAA é uma mistura fluida que proporciona diferenças de comportamento quando comparado ao concreto convencional. Neste contexto, a proposta desta pesquisa foi estudar, num primeiro plano, as características reológicas nas fases de pasta, argamassa e concreto do CAA no estado fresco e seu comportamento no estado endurecido. Para isso, optouse por empregar a metodologia de Repette e Melo (2005), que considera a resistência à compressão como ponto de partida para a composição do traço do CAA e que estuda os aspectos reológicos envolvidos nas diferentes fases de sua dosagem. Os materiais empregados para estudo de dosagem foram o fíler basáltico como adição, areia média, brita 19 mm, aditivo superplastificante e dois tipos de cimento. Foram elaborados dois concretos, com cimentos distintos, ambos com mesma classe de resistência igual a 40 MPa. Num segundo plano, foi realizado um estudo da avaliação da resistência à compressão desses concretos quando submetidos à cura térmica a vapor, variando-se as temperaturas de cura (entre 65oC e 80oC), assim como o patamar isotérmico de cura em 4 h,6 h e 8 h para cada temperatura. A avaliação das propriedades mecânicas dos concretos foi realizada empregando o Método da Maturidade. No emprego da maturidade foram utilizados as funções de Nurse e Saul e a proposta por Freiesleben-Hansen e Pedersen (FHP). As análises comparativas foram realizadas em função do tipo de cimento empregado, temperatura de cura e tempo de patamar isotérmico
The self-compacting concrete (SCC) is a material that represents one of the greatest advances in concrete technology in recent decades. The development of SCC has resulted in improved efficiency and working conditions at the construction site and the precast industry. Rheological point of view, the SCC is a fluid mix that provides behavior differences when compared to conventional concrete. In this context, the proposal of this research was to study, in the foreground, the rheological phases of paste, mortar and concrete of SCC in the fresh state and its behavior in the hardened state. For this, we chose to employ the methodology Repette e Melo (2005), which considers the compressive strength as a starting point for the composition of the trace of SCC and studying the rheological aspects involved in the different stages of their dosage. The materials used to study the dosage was basalt fillers such as addition, medium sand, gravel 19 mm, superplasticizer additive and two types of cement. We prepared two concretes with different cements, both with the same strength class of 40 MPa. In the background, a study assessing the compressive strength of concrete when subjected to steam curing, varying the curing temperatures (between 65oC and 80oC) as well as the level of isothermal cure at 4 h, 6 h and 8 h for each temperature. The evaluation of mechanical properties of concrete was carried out using the Maturity Method. Employment of maturity was used to Nurse e Saul function, as well as function proposed by Freiesleben-Hansen and Pedersen (FHP). Comparative analysis were performed according to the type of cement used, curing temperature and isothermal plateau
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Spáčil, Tomáš. "Bicí automat pro hudebníky." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2014. http://www.nusl.cz/ntk/nusl-220353.
Повний текст джерелаАнотація:
The aim of this work is to create a functional prototype of a drum machine with sound generating using a microcontroller. Introduction is devoted to general drum machine and an analysis of its parts, principle and basic modes of operation. The following chapter deals with the principle of digital signal processing and sound generation using a microcontroller. Part of this chapter is focused on mixing using compression methods. The core of this work is to design my own block structure and overall scheme of the drum machine with a description of the parts. Followed by analysis and implementation with theoretical and practical point of view. It is mainly about presentation and description of important parts of firmware codes, DPS design and another technical documentation useful for final prototype production. The conclusion contains a summary of the results with prezentation and discussion.
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Čupera, Pavel. "Trigenerace a její využití v praxi." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2009. http://www.nusl.cz/ntk/nusl-217827.
Повний текст джерелаАнотація:
e master's thesis clarifies the concept of trigeneration and the principle of absorbing cooling. Compare the advantages and disadvantages of this method of manufacture cool with compressor cooling. It presents an overview of the implementation of a developing cold absorption and performance. Acquainted with the types of absorption chillers of the two leading suppliers, their characteristics and existing applications of these refrigeration units in operation in the Czech Republic and abroad. It also assesses the possibility of using these units in conjunction with a cogeneration unit powered by internal combustion engine. It follows from the economic assessment of costs and income of the absorption chillers and compressor chillers and on concrete examples and an assessment of the effectiveness of the various options.
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Chou, Yuh-Shan, and 周鈺珊. "Bioactive Constituents from the Stems of Michelia compressa var. formosana." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/48035065274504960504.
Повний текст джерелаАнотація:
碩士輔英科技大學
醫學檢驗生物技術系碩士班
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Analysis of active ingredient in stems of Michelia compressa var. formosana (Magnoliaceae). Make the sample to dry, cut into small pieces and put into the glass bottle filled with methanol, after concentrated under reduced pressure to give an extracts of methanol. The methanol extracts using column chromatography and thin layer chromatography to made the purified compound, and to the composition and structure of the identification of NMR methods. We isolated seven compounds from the stems of M. compressa var. formosana including: liriodenine (1), (-)-N-acetylanonaine (2), pressalanine A (3), p-hydroxybenzaldehyde (4), 3,4-dihydroxybenzoic acid (5), (-)-bornesitol (6) and β-sitostenone (7). Among them, pressalanine A (3), 3,4-dihydroxybenzoic acid (5) and (-)-bornesitol (6) were isolated for the first time from this species.
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Chang, Tung-Yuan, and 張東源. "Compression Properties of Slag Cement Concrete Made by the Dry- Mix/Steam-Injection Procedure." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/27183615093099781434.
Повний текст джерела
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Jayaprakash, Narayan M. "Shock Wave-boundary Layer Interaction in Supersonic Flow over Compression Ramp and Forward-Facing Step." Thesis, 2014. http://hdl.handle.net/2005/3014.
Повний текст джерелаАнотація:
Shock wave-boundary layer interactions (SWBLIs) have been studied ex-tensively due to their practical importance in the design of high speed ve-hicles. These interactions, especially the ones leading to shock induced separation are typically unsteady in nature and can lead to large fluctuating pressure and thermal loads on the structure. The resulting shock oscil-lations are generally composed of high-frequency small-scale oscillations and low-frequency large-scale oscillations, the source of the later being a subject of intense recent debate. Motivated by these debates, we study in the present work, the SWBLI at a compression ramp and on a forward-facing step (FFS) at a Mach number of 2.5. In the case of compression ramps, a few ramp angles are studied ranging from small (10 degree) ramp angle to relatively large values of up to 28 degrees. The FFS configuration, which consists of a 90 degree step of height h, may be thought of as an extreme case of the compression ramp geometry, with the main geometri-cal parameter here being (h/δ), where δis the thickness of the oncoming boundary layer. This configuration is less studied and has some inherent advantages for experimentally studying SWBLI as the size of the separa-tion bubble is large. In the present experimental study, we use high-speed schlieren, unsteady wall pressure measurements, surface oil flow visualiza-tion, and detailed particle image velocimetry (PIV) measurements in two orthogonal planes to help understand the features of SWBLI in the com-pression ramp geometry and the forward-facing step case.
The SWBLI at a compression ramp has been more widely studied, and our measurements show the general features that have been seen in earlier studies. The upstream boundary layer is found to separate close to the ramp corner forming a separation bubble. The streamwise length of the separa-tion bubble is found to increase with the ramp angle, with a consequent shift of the shock foot further upstream. At very small ramp angles up to 10 degrees, there is no evidence of separation, while at large ramp angles of 28 degrees, the separation bubble extends upstream to about 3.5δ(δ=boundary layer thickness). In all cases, the separation bubble is however very small in the wall normal direction, typically known to be about 0.1δ, and hence is difficult to directly measure in experiments using PIV. Shock foot measurements using PIV show that the shock has a spanwise ripple, which seems directly related to the high-and low-speed streaks in the in-coming boundary layer as recently shown by Ganapathisubramani et al. (2007).
The forward-facing step configuration may be thought of as an extreme case of the compression ramp geometry, with a ramp angle of 90 degrees. This configuration has not been extensively studied, and is experimentally convenient due to the large separation bubbles formed ahead of the step. In the present work, extensive measurements of the mean and unsteady flow around this configuration have been done, especially for the case of h/δ=2, where his the step height. Pressure measurements in this case, show clear low-frequency motions of the shock at non-dimensional frequencies of about fh/U∞≈ 0.02. In this case, PIV measurements show the pres-ence of a large mean separation bubble extending to about 4hupstream and about 1hvertically. Instantaneous PIV measurements have been done in both cross-stream (streamwise and wall-normal plane) and in the span-wise (streamwise-spanwise) plane. Instantaneous cross-stream PIV mea-surements show significant variations of the shock location and angle, be-sides large variations in the recirculation region (or separation bubble), this being determined as the area having streamwise velocities less than zero. From a large set of individual PIV instantaneous fields, we can estimate the correlation of the measured shock location to both downstream effects like the area of the recirculation region, and upstream effects like the presence of high-/low-speed streaks in the oncoming boundary layer. We find that the shock location measured from data outside the boundary layer is more highly correlated to downstream effects as measured through the recircu-lation area compared to upstream effects in the boundary layer. However, we find that the shock foot within the boundary layer has ripples in the
spanwise direction which are well correlated to the presence of high-/low-speed streaks in the incoming boundary layer. These spanwise ripples are however found to be small (less than one h) compared to the highly three-dimensional shape of the recirculation region with spanwise variation of the order of 3 step heights.
In summary, the study shows that the separated region ahead of the step is highly three-dimensional. The shock foot within the boundary layer is found to have ripples that are well correlated to fluctuations in the in-coming boundary layer. However, we find that the large-scale nearly two-dimensional shock motions outside the boundary layer are not well cor-related to the fluctuations in the boundary layer, but are instead well cor-related with the spanwise-averaged separation bubble extent. Hence, the present results suggest that for the forward-facing step configuration, it is the downstream effect caused by the separation bubble that leads to the observed low-frequency shock motions.
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Hamza, Syed Muhammad Farrukh. "Shear-enhanced permeability and poroelastic deformation in unconsolidated sands." Thesis, 2012. http://hdl.handle.net/2152/ETD-UT-2012-08-6353.
Повний текст джерелаАнотація:
Heavy oil production depends on the understanding of mechanical and flow properties of unconsolidated or weakly consolidated sands under different loading paths and boundary conditions. Reconstituted bitumen-free Athabasca oil-sands samples were used to investigate the geomechanics of a steam injection process such as the Steam Assisted Gravity Drainage (SAGD). Four stress paths have been studied in this work: triaxial compression, radial extension, pore pressure increase and isotropic compression. Absolute permeability, end-point relative permeability to oil & water (kro and krw), initial water saturation and residual oil saturation were measured while the samples deformed.
Triaxial compression is a stress path of increasing mean stress while radial extension and pore pressure increase lead to decreasing mean stress. Pore pressure increase experiments were carried out for three initial states: equal axial and confining stresses, axial stress greater than confining stress and confining stress greater than axial stress. Pore pressure was increased under four boundary conditions: 1) constant axial and confining stress; 2) constant axial stress and zero radial strain; 3) zero axial strain and constant confining stress; and 4) zero axial and radial strain. These experiments were designed to mimic geologic conditions where vertical stress was either S1 or S3, the lateral boundary conditions were either zero strain or constant stress, and the vertical boundary conditions were either zero strain or constant stress.
Triaxial compression caused a decrease in permeability as the sample compacted, followed by appreciable permeability enhancement during sample dilation. Radial extension led to sample dilation, shear failure and permeability increase from the beginning. The krw and kro increased by 40% and 15% post-compaction respectively for the samples corresponding to lower depths during triaxial compression. For these samples, residual oil saturation decreased by as much as 40%. For radial extension, the permeability enhancement decreased with depth and ranged from 20% to 50% while the residual oil saturation decreased by up to 55%. For both stress paths, more shear-enhanced permeability was observed for samples tested at lower pressures, implying that permeability enhancement is higher for shallower sands. The pore pressure increase experiments showed an increase of only 0-10% in absolute permeability except when the effective stress became close to zero. This could possibly have occurred due to steady state flow not being reached during absolute permeability measurement. The krw curves generally increased as the pore pressure was increased from 0 psi. The increase ranged from 5% to 44% for the different boundary conditions and differential stresses. The kro curves also showed an increasing trend for most of the cases. The residual oil saturation decreased by 40-60% for samples corresponding to shallow depths while it increased by 0-10% for samples corresponding to greater depths. The reservoirs with high differential stress are more conducive to favorable changes in permeability and residual oil saturation. These results suggested that a decreasing mean stress path is more beneficial for production increase than an increasing mean stress path. The unconsolidated sands are over-consolidated because of previous ice loading which makes the sand matrix stiffer. In this work, it was found that over-consolidation, as expected, decreased the porosity and permeability (40-50%) and increased the Young’s and bulk moduli of the sand. The result is sand which failed at higher than expected stress during triaxial compression.
Overall, results show that lab experiments support increased permeability due to steam injection operations in heavy oil, and more importantly, the observed reduction in residual oil saturation implies SAGD induced deformation should improve recovery factors.text