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1
Jivanuwong, Solos. "Nondestructive Detection of Hollow Heart in Potatoes Using Ultrasonics." Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/36671.
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Ultrasonic techniques were used to detect hollow heart in potatoes nondestructively. Fifty Russet Burbank potatoes were evaluated physically and sonically. A pair of dry-coupling 50-kHz ultrasonic transducers were used to generate an ultrasonic pulse with a power level of 0.22 W for the test of acoustic transmission through whole potato tuber in a transverse direction at different locations along the longitudinal axis with a certain interval distance. It was found that the waveform analyses in time domain for a series of transmitted signals along the longitudinal axis of potato tuber, yielded the potential in detecting hollow heart in potatoes noninvasively. The transmission losses for potatoes having hollow heart were found to be greater than 0.28 dB/mm. This value was used as a criterion to indicate potatoes with hollow heart at an accuracy of 98 percent. The ability to detect hollow heart in potatoes was limited to a minimum cavity size of 0.5 cm3 because the interval distance between locations of measurement was relatively large compared to the size of the projected area of hollow heart. The accuracy of the detection would be improved if a smaller contact area for the transmitting transducer were used, and if the intervals between ultrasonic measurement locations were smaller.
Physical properties of the tested potatoes were also recorded for consideration of their relationships with ultrasonic parameters. Physical properties of tested potatoes such as modulus of elasticity, tuber length, diameter, and weight, were found to have poor correlation with ultrasonic parameters such as ultrasonic velocity, attenuation coefficient, and root mean square voltage of transmitted signal. This study showed that if all potatoes with weights of 300 g or less were eliminated from a mass of incoming potatoes, only 80 percent of the total mass would have to be examined for hollow heart.
Master of Science
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Cook, Corina K. "Hollow at the core apocalyptic visions in Joseph Conrad's Heart of darkness and T.S. Eliot's The waste land /." Instructions for remote access. Click here to access this electronic resource. Access available to Kutztown University faculty, staff, and students only, 2002. http://www.kutztown.edu/library/services/remote_access.asp.
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Thesis (M.A.)--Kutztown University of Pennsylvania, 2002.Source: Masters Abstracts International, Volume: 45-06, page: 2842. Typescript. Abstract precedes thesis as preliminary leaves 1-2. Includes bibliographical references (leaves 81-86).
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Astrouski, Ilya. "Polymeric Hollow Fiber Heat Exchanger Design." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2016. http://www.nusl.cz/ntk/nusl-240499.
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This Ph.D. thesis is focused on theory and experimental investigations developing of new knowledge about polymeric hollow fiber heat exchanger (PHFHE). The state-of-the-art study of plastic heat exchangers shows that their usage is limited by several niches where their advantages significantly dominates, or where the use of non-plastic competitors is not impossible. On the other hand, plastic heat exchangers (and PHFHEs in particular) are devices of increasing interest. It is shown that use of small tubes (fibers) allows PHFHEs to be more competitive than conventional plastic heat exchangers. Small hydraulic diameter of a fiber causes high heat transfer coefficients, reduces thermal resistance of plastic wall and allows it to create light and compact design. Detailed study of fluid flow and heat transfer inside the hollow fiber showed that conventional approaches for single-phase laminar flow can be utilized. Poiseuille number equal to 64 and Nussel number about 4 are recommended to be used to predict pressure drops and heat transfer coefficient, respectively. Additional attention should be paid to careful determination of fiber diameter and liquid properties (viscosity). Scaling effects, such as axial heat conduction, thermal entrance region and viscous dissipation can be neglected. The study of outside heat transfer showed that heat transfer on fiber bunches are intense and are competitive to contemporary compact finned-tube heat exchangers. The Grimson approach showed clear correlation with experimental results and, thus is recommended to predict heat transfer coefficients on fiber bunches. Two types of fouling (particulate- and biofouling) of outer fiber surface were experimentally studied. It was found that particulate fouling by titanium oxide particles is not intense and deposits can be removed relatively easy. However, fouling is much more intense when it is associated with biofouling caused by wastewater. In this case, smooth and low-adhesive surface of plastic is not sufficient precaution to prevent deposit formation.
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Ford, Theodore Robert. "Thermal conductivity of bonded hollow-sphere monoliths." Thesis, Georgia Institute of Technology, 1991. http://hdl.handle.net/1853/20045.
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Gonzalez, Ralph P. "Hollow sphere radiant thermal conductivity reduction using infrared pore opacification." Thesis, Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/20495.
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Bartuli, Erik. "Optimization of Heat Transfer Surfaces of Heat Exchangers." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-401602.
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Disertační práce je zaměřena na kovové a polymerní výměníky tepla. Hlavním předmětem zkoumání je optimalizace teplosměnných ploch za účelem zvýšení účinnosti výměníku tepla. Tyto cíle byly dosaženy experimentálně a numericky pomocí modelování v ANSYS. Na základě dosažených výsledků byla rozpracována technologie křížového navíjení polymerních výměníků z dutých vláken. Experimentální zařízení původně určené pro navíjení tlakových nádrží bylo modifikované pro automatizovanou výrobu polymerních výměníků z dutých vláken, ježto může být použita při jejich masové výrobě. Tato práce se také zabývala výměníky tepla pro klimatizační systémy. Byly zkoumány možnosti využití polymerních výměníků z dutých vláken v těchto systémech. Mimo jiné byla provedena studie vlivu cyklického tepelného zatížení standardního kovového žebrovaného tepelného výměníku.
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Anh, Viet Bui, of Western Sydney Hawkesbury University, of Science Technology and Environment College, and of Science Food and Horticulture School. "A study of osmotic distillation in hollow fibre modul." THESIS_CSTE_SFH_Anh_V.xml, 2002. http://handle.uws.edu.au:8081/1959.7/4.
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Osmotic distillation is a process of removing water from an aqueous solution, driven by water vapour pressure gradient across a hydrophobic membrane. The process occurs at or below ambient temperature and under atmospheric pressure. This research project investigates the osmotic distillation process in hollow fibre modules using hollow fibres PP375, PV375 and PV660 supplied by Memcor Australia. Operating conditions such as temperature, feed concentration and brine cross flow velocity, but not the feed cross flow velocity, were found to have significant effect on the flux. Models for heat and mass transfers were used to study the polarisation phenomena in osmotic distillation. Temperature and concentration profiles at the membrane surfaces due to polarisation were quantified. Scholfield and Ordinary Diffusion models for flux prediction based on the bulk conditions were developed and validated. Models for water activity and viscosity of aqueous glucose and calcium chloride solutions were also developed and validated in this work.Master of Science (Hons)
8
Shapiro, Michael Jay. "An experimental investigation of the thermal conductivity of thin-wall hollow ceramic spheres." Thesis, Georgia Institute of Technology, 1987. http://hdl.handle.net/1853/8667.
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Bokišová, Lenka. "Konstrukční řešení teplosměnné plochy a její zanášení u výměníků z dutých plastových vláken." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-230426.
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This thesis studies a possibility of using hollow fibres for construction of innovative heat exchangers. The first part introduces to the field of heat exchangers and polymers as materials suitable for formation of heat transfer surfaces. Further, the potential of hollow fibres of small diameters is outlined, including the merits, limits and proposals for improving. The significant part of the work is dedicated to the review of methods of fibres fixation and separation and review of fouling and cleaning of heat exchangers. Overviews of design possibilities which prevent fibres clustering have been made. The solutions, which are prepared for experimental research at Heat Transfer and Fluid Flow Laboratory are stated, including analysis of “curly” fibres application. The next part presents calculations for models of water – water and water – air heat exchangers and discusses influence of fibre diameter, flow velocity and the other parameters on heat characteristics. The heat transfer and fluid flow formulas using for heat exchangers of a bigger order can be employed with small changes. Furthermore, the influence of hollow fibres arrangement and distances on heat transfer is discussed.
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Ondrejka, Filip. "Nekonvenční chladicí systémy pro Formuli Student." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-444964.
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This master’s thesis deals with the design and manufacture of a heat exchanger with polymeric hollow fibers for a Formula Student vehicle. The work can be divided into three parts. The first part contains a review of heat transfer and heat exchangers, the second part deals with polymeric fiber heat exchangers design and manufacture of of polymeric hollow fibers heat exchanger with a heat exchanger for a Formula Student vehicle. The last part deals with the comparison of polymeric hollow fibers heat exchanger with the original aluminum heat exchanger and the evaluation of the measurement results.
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Kůdelová, Tereza. "Fázové změny na povrchu tepelných výměníků s dutými vlákny." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2018. http://www.nusl.cz/ntk/nusl-375535.
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The thesis focuses on the polymer hollow fibres heat exchangers. The main object of the research is the formation and process of condensation on the outer surface of fibres and the effect of phase change on the heat transfer. The study deals with the influence of the geometry of the heat exchnager on the heat transfer and the condensation process. Fatigue tests of polymeric hollow fibres exchangers are also part of the work. The work provides an overview of the possible use of such heat exchangers in industrial applications associated with condensation.
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Holle, Ann-Kathrin [Verfasser], and Stefan [Akademischer Betreuer] Blankenberg. "Klinische Evaluation des Heart Type Fatty Acid Binding Protein in der Diagnostik der frühen Phase des akuten Koronarsyndroms / Ann-Kathrin Holle. Betreuer: Stefan Blankenberg." Hamburg : Staats- und Universitätsbibliothek Hamburg, 2014. http://d-nb.info/1049281543/34.
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Sridi, Ahmed. "Modélisations thermomécanique et numérique du comportement de maçonneries en briques alvéolées en terre cuite sous chargements mécanique et thermique sévères." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLC047/document.
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Un des enjeux majeurs de la filière de construction en briques alvéolées est l’amélioration de la tenue au feu de hauts et ambitieux bâtiments, réalisés avec ces briques. L’objet de nos travaux est de développer des modèles thermo-mécaniques et des outils numériques suffisamment prédictifs pour orienter la recherche, par la simulation numérique, de produits améliorés vis-à-vis de la tenue au feu, permettant de diminuer le nombre de coûteux essais expérimentaux. Les contributions principales sont d’ordre méthodologique. Nous avons ainsi établi un dialogue entre les observations, les mesures et les résultats expérimentaux, d’un côté, les modèles et les simulations de l’autre, avec un souci permanent de diminution des coûts des simulations. Ainsi, tirant profit de résultats de mesures réalisées, nous avons développé progressivement des modélisations adaptées, en examinant l’importance des phénomènes thermiques (conduction, convection et rayonnement), en recherchant les « juste-bonnes» (par rapport aux objectifs) relations d’échanges aux multiples interfaces du problème et en introduisant le changement de phase de l’eau liée. Nous avons également été amenés à identifier, par approche inverse, certains paramètres, après avoir identifié les bons mécanismes thermo-mécaniques. Enfin, pour mieux inscrire nos travaux dans une démarche d’aide efficace à la conception, nous avons travaillé dans le cadre multimodèle et multiéchelle Arlequin pour formuler, approcher et résoudre les problèmes thermo-mécaniques résultants, comportant des zones de concentrations du gradient thermique et de singularités mécaniques. L’approche globale, élaborée et testée, en utilisant différents codes et en développant des parties d’autres, montre une capacité réelle à améliorer les calculs des structures en briques alvéolées, soumises à des chargements thermo-mécaniquesOne of the major challenges of the hollow clay brick industry nowadays is to improve the fire resistance of ambitiously tall buildings, constructed with this type of bricks. The objective of our work is to develop thermo-mechanical models and related predictive numerical tools to guide the research of improved fire-performance products and therefore reduce the number of expensive experimental tests. Our main contributions are methodological. With a permanent concern of reducing the simulation costs, we establish a dialogue between observations, measurements and experimental results, on the one hand, models and simulations on the other hand. In this regard, measurements, obtained during the experimental tests we carried out, are used to progressively develop relevant models, by examining the importance of thermal phenomena (conduction, convection and radiation), by looking for the just right transfer relations (with respect to our objectives) at the multiple interfaces of the problem and by considering the phase change of bound water. After identifying the good thermo-mechanical mechanisms, we calibrate some numerical parameters by solving an inverse problem. Moreover, to efficiently help the design of new products, we employ the multi-model and multi-scale Arlequin framework to formulate, approximate and solve resulting thermo-mechanical problems. The latters include areas of thermal gradient concentrations and mechanical singularities. Our global approach implemented and tested by developing codes and enriching others, shows a real ability of our methodology to efficiently compute structures made of hollow bricks, when subjected to thermomechanical load
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Hvožďa, Jiří. "Matematický model membránové destilace." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-445459.
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Diplomová práce se zabývá membránovou destilací, především z matematické perspektivy. Jedná se o tepelně poháněný separační proces, ve kterém se pro rozdělení kapalné a plynné fáze používá porézní membrána. Kapalina se vypařuje a její plynná fáze prochází přes póry v membráně. Během tohoto procesu dochází k tepelné i látkové výměně, které jsou popsány systémem parciálních diferenciálnich rovnic. Další model je založen na analogii s elektrickými obvody, zákonu zachování energie, hmotnostní bilanci a empirických vztazích. Je ověřen s experimentálně naměřenými daty z nové alternativní destilační jednotky používající membránu a kondenzátor z polymerních dutých vláken. Výkon a účinnost jednotky jsou vyhodnoceny. Další možná vylepšení jsou navržena.
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Reynolds, Rema Ella. "Holla if you hear me giving voice to those we have missed : a qualitative examination of black middle class parents' involvement and engagement activities and relationships in public secondary schools /." Diss., Restricted to subscribing institutions, 2009. http://proquest.umi.com/pqdweb?did=1835603611&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.
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Jelínek, Roman. "Bytový dům ve Zlíně." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2013. http://www.nusl.cz/ntk/nusl-225804.
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The aim of this thesis is to elaborate project documentation for new construction of low-energy residential building with 16 luxury apartments, apartment without barriers and with pharmacy of basic type. It is a four-storey detached building without basement, with flat roof, roof terraces and with balconies. Residential building is located in one of the most enjoyable parts of the city of Zlín – Jižní Svahy II in the vicinity of Central park with bicycle path and with beautiful view of the Zlín. The building will be located on land plot No. 2144/46, where is still situated unfinished building "Torso" from the late 80 years. The residential building is designed in brick system Heluz, ceiling construction is made up of prestressed hollow core slabs, perimeter walls are with external thermal insulation composite system and external doors and windows are made of plastic and aluminum with triple glazing. For heating and water heating will be utilized renewables energy, such as heat pump and solar collectors. Residential units with three residential rooms are designed with a forced ventilation by means of ventilation units with heat recovery. The building also uses modern shielding elements such as outdoor blinds and horizontal sun breakers. The part of the project are also disposition studies, seminar work and energy part.
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Balasubramanian, Holly Ann. "Heat-mass-momentum transfer in hollow fiber spinning." Thesis, 2004. http://hdl.handle.net/2152/1477.
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Balasubramanian, Holly Ann Lloyd Douglas R. "Heat-mass-momentum transfer in hollow fiber spinning." 2004. http://repositories.lib.utexas.edu/bitstream/handle/2152/1477/balasubramanianh94421.pdf.
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Weinberg, Alon David. "Dialogue, displacement and return - contexts of a journey on a two-way road: Anishinaabek responses to all-weather roads through Waabanong Nakaygum: memory and continuity on the eastern shores of Lake Winnipeg and beyond." 2014. http://hdl.handle.net/1993/23243.
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East of Lake Winnipeg is what conservationists call the ‘east shore wilderness’ / ‘heart of the boreal.’ The largest contiguous tract of unindustrialized boreal forest on Earth, this area has been the focus of 15 years of discussion and planning in Manitoba. The area is also designated Waabanong Nakaygum, a homeland to the Anishinaabek of this bush-meets-lake region. Waabanong has seen limited access during the industrial period of personal mechanized mobility due to a lack of constructed all-weather roads. However, an older pattern of travel and mobility does exist across the land, for centuries constituting traditional Anishinaabek patterns of land use and trade. As all-weather roads are being constructed along Lake Winnipeg, oral interviews will examine the question: will the older trails remain in the collective culture of the people or shall the north-south cultural and economic flows replace the east-west bush history traced by the rivers that wind through?
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Chih-ChengHuang and 黃志誠. "Heat Conduction of Hollow Cylinders with Time-Dependent Boundary Conditions and Heat Convection Coefficients." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/71527168018617045126.
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博士國立成功大學
機械工程學系碩博士班
101
The analytic solutions for the transient heat conduction by extending the method of shifting function in (I) functionally graded circular hollow cylinders with general time-dependent boundary conditions, and (II) uniform circular hollow cylinders with time-dependent boundary condition and heat convection coefficient are developed. The proposed solution method is free of integral transforms. Limiting studies and numerical analysis are given to illustrate the efficiency and the accuracy of the analysis. The influences of physical properties on the heat conduction behavior of the system are studied.
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Hsu, Hsiung-Chun, and 徐熊群. "Heat Transfer Measurements of Perforated Hollow Cylindrical Fins in Staggered Alignment." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/c83e6u.
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碩士國立虎尾科技大學
機械與機電工程研究所
99
In this study, heat transfers of perforated hollow cylindrical fins in staggered alignment are experimentally measured. Both of the natural convections and impingement flows of four cases of fin structure are investigated. The fin structures are designed with 8 pins, 14 pins, 23 pins, and 33 pins, respectively; and the corresponding spacing ratio Sx is ranging from 1.7 to 0.9, respectively. As to the natural convection experiments, input powers are varied from 10W to 30W and its corresponding Rayleigh numbers are varied from 1 x 106to 5 x 106. Considering the impingement flow experiments, the input powers are varied from 32.5W to 181.45W, and Reynolds numbers are changed from 16699 to 150291. The test rig of natural convection experiments is constructed by Bakelite materials and is carefully insulated. A T-tube channel made by Acrylic is used to conduct the impingement flow experiments. Both experiments are conducted according to the corresponding experimental conditions, and experimental data are collected by a logger for post analysis. According to the experimental results shown, for natural convection flows, the Nusselt numbers evaluated from experiments, as comparing to the reference [31], is higher than the one of solid and hollow fins under the same conditions. Comparing to the case of solid fins, its Nussult number increases from 30% to 35%; comparing to the case of hollow fins, its Nussult number increases from 2% to 5%. For impingement flow experiments, if spacing ratio Sx is increasing from 0.9 to 1.7, pressure drops will decrease 40%. Therefore, it can be noted that increasing Sx will increase the heat transfer of the fin structures. Increasing input powers can decrease the thermal resistances up to 50%. By the results of fin efficiency, for higher Reynolds numbers, fin efficiency is decreased as spacing ratio. It shows that for higher Reynolds numbers and smaller spacing ratio, the fin efficiency is smaller. This study shows that the fin structures with perforated hollow cylindrical fins in staggered alignment is feasible to and applicable as heat dissipation mechanisms of LED lightings or electronic devices.
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Wang, Meng-Ping, and 王孟平. "FORCED CONVECTIVE HEAT TRANSFER IN A RECTANGULAR HOLLOW OR POROUS CHANNEL." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/81558176442663752036.
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碩士國立清華大學
動力機械工程學系
88
ABSTRACT A series of experimental investigations with a stringent liquid crystal transient method on the studies related to the convective heat transfer in hollow and porous channels have been successfully performed. For the study on the heat transfer in a rectangular hollow channel, the local spanwise-averaged Nusselt number decreases along the streamwise direction. A symmetric distribution of heat transfer coefficients in the spanwise direction has been verified; and a maximum Nusselt number exists at the center location of the test channel inlet for all the experimental cases. The effect of the air preheating temperature on local and average Nusselt numbers is not significant; while the local and average Nusselt numbers increase with increasing Reynolds number in a power of 0.55. The local and average Nusselt numbers on the test channel surface for material Type (II) are higher than those for material Type (I). These Nusselt numbers for the cases of wall material Type (II) will approach those for the cases of material Type (I) when the Reynolds number increases. Additionally, two new empirical correlations of heat transfer in a hollow channel for wall material Type (I) and Type (II) are respectively proposed. For the study on the heat transfer in a rectangular porous channel, the local Nusselt number increases from the channel inlet to X=0.15-0.20 and then gradually decreases along the streamwise direction. A uniform distribution of local Nusselt numbers in spanwise direction at a specified streamwise location can be found. A maximum heat transfer is generally existed around X=0.15-0.20 for all the experimental cases. The effect of the air preheating temperature on local and average Nusselt numbers is not significant. The local and average Nusselt numbers increase with increasing Reynolds number or decreasing medium porosity. The peak of the distribution of local Nusselt number becomes more sharper when the Reynolds number increases. The medium porosity has a significant influence in the entrance region of the channel, i.e., X<0.5; while its effect is gradually diminished along the streamwise direction in the region of 0.5￡X<1.0. No significant deviation on the local and average Nusselt numbers for material Type (I) and Type (II) . Besides, all the ratios of are much greater than unity. Two new correlations of in terms of Re, e and Da for wall material Type (I) and Type (II) are proposed. Furthermore, a concept of the amount of enhanced heat transfer is introduced. Based on all the experimental data in the experiments of porous channels, a new empirical correlation of j/f in terms of e and Re is proposed in the study.
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Wu, Yueh-Chan, and 吳岳展. "Two-Dimensional inverse problem in estimating heat sources of a hollow cylinder." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/74349280166561454988.
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碩士國立中興大學
應用數學系所
102
This study is to pretict the heat sources of hollow cylinders inversely by a hybrid numerical method. First, the r and z domains are divided into equally small elements Δr and Δz, respectively. Next, one discretizes the governing equation through the second-order finite difference method. The Savitzky-Golay digital filter is then used to smoothen the measurement error. Then, substituting the thermal conductivity, boundary into the finite difference equations, and using MATLAB software to calculate inversely difference equations for heat sources. The results are, finally, undergone a polynomial regression to obtain the empirical correlation for heat sources. The study discusses the influences of simulating measurement errors ω (1%, 3% and 5%), the numbers of the measured points(n, m) and the width of smooth window N to analyze predicting the strength of heat sources. The results show that the more the measured points, the lower is the error of estimations through a hybrid numerical method. The accuracy of the calculated inversly the value of heat sources increases with a decrease in the measurement errors or an increase in the width of the smooth window. Using the second-order finite difference method and Savitzky-Golay digital filter to calculate inversely the strength of heat sources and applying the polynomial regression to obtain an empirical correlation is a simple and effective way.
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Ma, Zhengyuan. "Mechanical properties of heat-treated and hot-dip galvanized rectangular hollow section material." Thesis, 2018. https://dspace.library.uvic.ca//handle/1828/10411.
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Hot-dip galvanizing is widely used for corrosion protection of steel structures. However, there has been a plethora of recent reports on premature cracking in galvanized steel structures, which have resulted in some early decommissions or even hazardous collapses. This research focuses on cold-formed Rectangular Hollow Sections (RHS). A total of 108 tensile coupons were tested to investigate the effects of galvanizing as well as different pre-galvanizing treatments on the material properties around the cross sections of the specimens. For the first time, this thesis reports a comprehensive measurement of residual stresses in different directions at the member ends which are directly relevant to the cracking issue. The results were also compared to the residual stresses far away from the member ends, which are relevant to structural stability research. In all, the research provides a better understanding of the characteristics and structural performance of galvanized RHS to facilitate its application. The recommendations can help engineers, fabricators, and galvanizers mitigate the risk of cracking in RHS during galvanizing.Graduate
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Ciou, Yong-Sheng, and 邱永勝. "Effect of heat treatment on the pervaporation performances of PAN hollow fiber membrane." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/p7ah7a.
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碩士中原大學
化學工程研究所
92
In this study, Heat-treated polyacrylonitrile (PAN) hollow fiber membranes were prepared by heat-treating the PAN precursor hollow fiber membrane with different heat-treatment conditions. The influence of heat-treatment conditions on the pervaporation performances of aqueous isopropanol (IPA) solution through heat-treated PAN hollow fiber membranes were investigated. It shows that the permeation rate decreases and the water content in permeate increases with increasing heat-treatment temperature in the range of 60-180 OC. Nevertheless, the permeation rate increases again as the heat-treatment temperature increases. The permeation rate and water content in the permeate for a 90wt% aqueous isopropanol solution through the heat-treated PAN hollow fiber membranes at 120℃ for 12h were 186 g/m2h and 99.2 wt﹪, respectively. The SEMs observation depicts that the morphology of heat-treated PAN hollow fiber membranes were denser with increasing the heat-treatment temperature. As the heat treatment temperature higher than 210oC, dehydrogenation and cyclization reaction of the PAN molecular occurred during the heat-treatment process. Moreover, the inference of feed temperature and feed composition on the pervaporation performance through heat-treated PAN hollow fiber membranes were also investigated. It shows that an increase in the feed isopropanol concentration results in a decrease in the permeation rate and an increase in the separation factor. And the permeation rate increase and the separation factor decrease with increasing the feed solution temperature. The pervaporation performances for 90 wt% ethanol solution, isopropanol solution and tetrafluropropanol solution through heat-treated PAN hollow fiber membranes were also investigated. The tetrafluropropanol solution gave the best separation performance through heat-treated PAN hollow fiber membranes.
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MIN-LANG, YANG, and 楊敏郎. "Study on lightweight concrete hollow bricks used in buildings for improve heat insulation and waterproofing." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/01932276467463568538.
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碩士建國科技大學
土木與防災研究所
100
An increase in global temperature causes glaciers to melt and the sea levels to rise. The rainfall is not regular, either drought or heavy rain,which caused tremendous disaster. Taiwan is located in East Asia, where is in the sub-tropical climate zone.The land is affected by the continental and marine climate patterns In Taiwan from April to May are the plum rain seasons while June and July for the afternoon rainstorm, then in July, August and September are typhoon season. With the increasing rainfall, the roof of the building would withstand a direct impact. Therefore, there would be the leakage and seepage.There are always extra tin roof on the detached houses for preventing the leakage and the heat.but it would result in the ugly landscape and the public issue. For saving the cost, some building construction companies use cheap and simple way to make the roof. But it would be followed by the problems of rising maintenance expense in the future. This thesis is analyzing the methods of building the flat roofs on new buildings and existing buildings ,as well as the materials. The author indicates that the use of light concrete hollow brick applications can : (1) reduce maintenance costs, improve construction efficiency. (2) reduce waste, and reduce the carbon environmental benefits. (3) provide comfortable living,appearance, and save electricity costs. The conclusions are achieved through simple experiments, materials analysis, and the household interviews. The living environment would be comfortable, energy efficiency and cost reducing.
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YE, RONG-PENG, and 葉榮鵬. "Temperature distribution and thermal stress analysis of a hollow cylinder subject to a moving heat source." Thesis, 1986. http://ndltd.ncl.edu.tw/handle/80701483816786263802.
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Li, Shi-Wei, and 李世偉. "Effect of spinning condition on membrane morphology and pervaporation performance of heat-treatment PAN hollow fiber membranes." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/29804328127254273185.
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碩士中原大學
化學工程研究所
99
In this study, stabilized polyacrylonitrile(PAN) hollow fiber membranes were fabricated by heat-treating dry/wet spun asymmetric PAN hollow fiber membrane. The effects of spinning conditions(such as Dope solution concentration, air gap, bore liquid composition)as well as heat-treatment process(temperature and time)on the morphology of PAN hollow fiber membrane and pervaporation performances of 90 wt.% aqueous ethanol solution through hollow fiber membrane were investigated. The results showed that the pure water flux decreased but the permeation rate increased while water concentration in permeate constant with increasing PAN content in the dope for the heat-treated PAN hollow fiber membranes. These phenomena might be due to with increasing PAN content in the dope the dehydrogenation and cyclization reaction have occurred during the heat-treatment process will be increased. The SEMs observation depicts that the morphology of heat-treated PAN hollow fiber membranes were denser with increasing the heat-treatment temperature. As the heat treatment temperature is 210 ℃, dehydrogenation and cyclization reaction of the PAN molecular occurred during the heat-treatment process. So the pervaporation performances increased. And then constant the heat treatment temperature is 210 ℃and change the heat treatment time, the pervaporation performances decreased and then increased. These phenomena might be due to two effect control.The results can find the best heat-treatment process condition is 210 ℃、12hr. In the study, want to control membrane structure of macrovoids were passed through the entire cross section of PAN hollow fiber membrane to decreased the resistance , so changing the spinning condition of bore liquid composition and air gap. The results show that change bore liquid composition can not increase the pervaporation performances, but when change the air gap to 30 cm can get the best pervaporation performances.And then the hollow fiber membrane free volume size and distribution and variation in the multilayer structure were probed using a variable monoenergy slow positron beam (VMSPB) to understand the relationship between the membrane separation performance and free volume.
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Chen, Bo-Syun, and 陳柏勛. "The study of heat-treatment on the morphology and pervaporation performances of PI/PAN hollow fiber membranes." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/11588959275810605511.
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碩士桃園創新技術學院
材料應用科技研究所
100
In this study, the effect of spinning and heat-treatment on the morphology and aqueous alcohol solution pervaporation performances of Polyimide (PI)/ Polyacrylonitrile (PAN) hollow fiber membranes were investigated. Three kinds of hollow fiber membranes were fabricated in this study such as PI/PAN dual-layer hollow fiber membranes, PI/PAN blend hollow fiber membranes and PI/PAN hollow fiber membranes with various solvent systems. The results show that the PI/PAN dual-layer hollow fiber membranes were delaminated after heat-treatment. The pervaporation performances of heat-treated dual-layer PI/PAN hollow fiber membranes were dominated by the outer layer of PI layer. By comparing the 90wt.% aqueous isopropanol solution pervaporation performance at 25OC through heat-treated PI hollow fiber membranes as heat-treatment temperature lower than 210OC, the permeation flux of PI/PAN dual-layer hollow fiber membranes were higher than PI hollow fiber membranes. These phenomenon might be due to the fact that the PI layer thickness of duel-layer hollow fiber membrane was thinner than PI hollow fiber membrane resulted in the lower permeate thanfer resistance, thus, the permeation flux increased and water content in permeate decreased. As the heat-treated temperature was increased to 240OC, no matter PI/PAN dual-layer or PI hollow fiber membrane, the performances inclused permeation flux and water content in permeate were the same. As for the PI/PAN blended system, there are many strip pores on the inner and outer surface of as-spun blended hollow fiber membranes as increasing the PI content. In the cross-sectional morphology, there are many also many pores between PI fiber and PAN matrix. These pores could provide more permeation flux and decrease water content in permeate. The morphology of PI/PAN blend hollow fiber membranes were densify by heat-treating the as-spun PI/PAN blend hollow fiber membranes and resulted in the decrease of permeation flux and increase the water content in permeate. The optimal pervaporation performances of 90wt.% aqueous isopropanol solution at 25OC could be gotten through the heat-treated PI/PAN(10/90) blended hollow fiber membranes. The permeation flux and water content in permeate were 294 g/m2h and 95 wt.%, respectively. The PI/PAN(10:90) hollow fiber membranes were also prepared by various solvent systems such NMP, FMAc and DMF. The results show that by using NMP as the solvent to dissolve PI or PAN polymer, the highest viscosity of PI/PAN(10:90)/solvent solution could be prepared. On the contrary, the lowest viscosity could be gotten by using DMF as the solvent. The optimal pervaporation performances of 90wt.% aqueous isopropanol solution at 25OC could be gotten through the heat-treated PI/PAN(10/90)/DMAc blended hollow fiber membranes. The permeation flux and water content in permeate were 203 g/m2h and 99wt.%, respectively. The pervaporation operation conditions such as feed concentration, feed temperature and feed alcohol through PI/PAN(10:90)/DMAc heat-treated hollow fiber membranes were also investigated in this study. The permeation flux increased while water content in permeate decreased with increasing feed temperature. The permeation flux also increased with decreasing isopropanol concentration in feed. By increasing the carbon number of feed alcohol, the permeation flux decreased slight while water content in permeate almost kept 99 wt.%.
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Wu, Jin-Rong, and 吳進榮. "Conjugated Heat Transfer Analysis of Wall Conduction and Mixed Convection for Non-Newtonian Fluids over Vertical Slender Hollow Cylinders." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/19517362403370081710.
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碩士明志科技大學
機電工程研究所
101
In this thesis, the steady laminar convective heat transfer of non-Newtonian fluids flowing over a vertical slender hollow cylinder has been investigated. By considering the interaction between wall conduction and mixed convection, an analysis is presented to study the conjugate heat transfer characteristics. In addition, the power-law model is used for non-Newtonian fluids with exponent n < 1 for pseudoplastics fluids, n = 1 for Newtonian fluids, n > 1 for dilatant fluids. A conjugate heat transfer parameter is proposed as control indicators to show the impact of the wall heat conduction. The coordinates and dependent variables are transformed to yield computationally efficient numerical solutions. The effects of the conjugate heat transfer parameter, the buoyancy parameter, the curvature parameter and the Prandtl number on the fluid fields and the thermal fields, so that the skin friction group and the heat transfer group will be discussed in depth.
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Dai, Xianghe, and Dennis Lam. "Shape effect on the behaviour of axially loaded concrete filled steel tubular stub columns at elevated temperature." 2012. http://hdl.handle.net/10454/5883.
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Concrete filled steel tubular columns have been extensively used in modern construction owing to that they utilise the most favourable properties of both constituent materials. It has been recognized that concrete filled tubular columns provide excellent structural properties such as high load bearing capacity, ductility, large energy-absorption capacity and good structural fire behaviour. This paper presents the structural fire behaviour of a series of concrete filled steel tubular stub columns with four typical column sectional shapes in standard fire. The selected concrete filled steel tube stub columns are divided into three groups by equal section strength at ambient temperature, equal steel cross sectional areas and equal concrete core cross sectional areas. The temperature distribution, critical temperature and fire exposing time etc. of selected composite columns are extracted by numerical simulations using commercial FE package ABAQUS. Based on the analysis and comparison of typical parameters, the effect of column sectional shapes on member temperature distribution and structural fire behaviour are discussed. It shows concrete steel tubular column with circular section possesses the best structural fire behaviour, followed by columns with elliptical, square and rectangular sections. Based on this research study, a simplified equation for the design of concrete filled columns at elevated temperature is proposed.
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Wang, Yu-Liang, and 王友良. "Holler If You Hear Me: Taiwanese Hip Hop Music under the Transnational Cultural Flow in East Asia." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/44gyb8.
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碩士國立臺灣師範大學
英語學系
103
Abstract The thesis focuses on the transnational collaborations of Taiwanese hip hop music in East Asia. Over the past twenty years, Taiwanese hip hop music has transformed from the stages of initial imitation and appropriation of the music form, the domestication of local culture to the present transnational crossover collaborations among East Asian countries. Transnational Taiwanese hip hop music brings abundant cultural diversity and flow and also presents the possibility of “trans-Asian” hip hop. The thesis consists of three chapters. The first chapter probes into the history of hip hop culture, the art form of rap music, and the globalization of hip hop. By adopting Arjun Appadurai’s “scape” theory, I indicate that ethnoscapes and mediascapes are related to the globalization of hip hop, along with the mutability of rap to develop hip hop in different cultures. The second chapter draws the attention on the development of hip hop music in the context of East Asian countries by discussing specific issues as Korean Wave/K-pop, J-hip hop and J-R&;B to thus suggest that the interrelations of hip hop’s cross-cultural and regional experience in East Asia has the great influence on Taiwanese hip hop music. In Chapter Three, I first summarize the history and development of Taiwanese hip hop and take Taiwanese hip hop group Da Mouth, singer Nicky Lee, music producer Jae Chong and rapper Softlipa to be the cases to analyze their images, music style and experience of East Asian collaborations. I argue that transnational Taiwanese hip hop music in East Asia has come to possibility through global mobility of diaspora, transnationalism and transbordering identities.
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Cooper, Theressa N. "“Holla if you hear me”: A Conversation with Black, inner-city youth on career preparedness programs." 2010. http://trace.tennessee.edu/utk_graddiss/874.
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This research study specifically addressed; how vocational preparedness programs effect the career aspirations of Black youth, within the context of the Middle Tennessee Council Boy Scouts of America’s Exploring program. The goal of this research is to represent Black youth participating in a vocational preparedness program. Interviews, journals, and rich, thick descriptions are utilized in this work.
Using the lens of narrative inquiry and cultural studies, I hoped to further the field of career development through the experiences of some of its key players, African American youth. Within the context of their stories five major themes surfaced around the ideas: (1) Advancement via Individual Determination. (AVID), (2) Career Self-efficacy, (3) Roles of significant others in career development, (4) Perceptions of the Exploring program, and (5) what would you like to see happen in the Exploring program?
Beyond themes expressed by the research participants, the following underlying factors also came to light; (1) giving voice to Black youth which are part of the marginalized minority population and restoring a sense of narrative power and authority to the youths telling the stories, (2) The Advancement Via Individual Determination (AVID) program as a significant influencer, (3) structure and organization of the Learning for Life program, (4) the role of Black women as significant others in the career decisions of participants, and (5) career choice – trade vs. careers.