With an increase of interest in space flight and vacuum research, there has been a corresponding increase in the need for values of outgassing rates of many materials. In space flight the knowledge of the outgassing rates of components and materials used in construction of space vehicles allow the determination of pressures within sections of the vehicle, the contamination level of critical components, and the reliability of vehicle components. In the construction of an ultra high vacuum facility, the knowledge of the value of the outgassing rates of construction materials allows the chamber to be constructed of low outgassing materials, minimizing the amount of gas evolving from the chamber walls. With the initiation of a research program, the outgassing rates of the chamber, test objects, and instrumentation are needed to determine the level of vacuum obtainable during the investigation.<br /> With the increased need for outgassing rates, more emphasis has been placed on the measurement of outgassing rates. The literature reports several techniques for the measurement of outgassing rates. Of these techniques, the rate of rise method is simple and convenient to apply, and hence of much interest. Because it is simple and easily applied, the rate of rise technique has been used by many experimenters to measure the outgassing rates of various materials. However, some experimenters have rejected its use as they felt that the dynamic nature of the technique introduced large errors into the outgassing measurements. There is presently in the literature no technical evaluation of the rate of rise method as to the suitability or unsuitability for measuring outgassing rates. / Master of Science

Increasing global competition, high stumpage and energy prices, and the slowing housing market have challenged the U.S. hardwood lumber industry during the past several years. Many wood product manufactures are trying to remain in business by implementing continuous improvement programs like lean manufacturing. However, the lumber drying process where lumber is kiln-dried in large batches, can significantly increase manufacturing and inventory lead-time; and is a process that tends to limit how lean the remaining process can become. Vacuum drying has the potential to reduce drying times, reduce batch sizes and achieve product quality comparable or superior to conventional drying. The overall goal of this research was to evaluate how vacuum-drying technology could support further lean implementation in manufacturing of hardwood products. Specifically, to estimate conventional and vacuum drying times, quality, and costs for drying 4/4 red oak lumber; to determine by the use of feasibility analysis (cash flow, net present value, and internal rate of return) differences between conventional and vacuum drying for 4/4 red oak lumber; and to determine if the high capital cost of vacuum drying equipment can be justified with the reduction of WIP and cycle time, while meeting desired throughput. The study includes a cost analysis of vacuum and conventional drying, and a determination of the potential financial gains associated with the reduced drying times via vacuum drying. It was determined that vacuum drying quality was equal or better than conventional drying with less checking, end splits, drying stress and shrinkage. Compared to conventional drying, vacuum drying times with air drying and without air drying were 67% less and 70% less, respectively. Conventional and vacuum with no air drying scenarios were determined to be financially feasible when compared using Net Present Value and Internal Rate of Return analysis. However, vacuum drying with no air drying had better NPV and IRR values than conventional drying. The scenario of vacuum with air drying was not feasible. Two case studies, each employing the three drying scenarios (conventional drying, vacuum with air drying, and vacuum without air drying), were used to determine the impact of cycle times and work in process. It was determined that the cycle times for vacuum drying were 87% and 95% less than conventional drying for the first case study and 51% and 90% less than conventional drying for the second. WIP was 48% and 84% less in the first case study and 43% and 92% less than conventional drying for the second. Cycle time was reduced by 87% and 51% for Plant C and D, respectively. Finally it was determined that the reduction of WIP represented a cost saving of 73% and 76% for the two case studies. The reduction in costs, faster drying rates, and equal quality, and reduced cycle times make vacuum drying a potential technology available for improvement of the competitiveness for flooring manufacturers. / Master of Science

Prior to launch, space craft instruments need to be tested in a relevant environment to prove operational functionality. Thus, we have developed an ion source to stimulate thermal plasma instruments in a vacuum chamber. This dissertation presents the mechanical design of the source, simulations of the potentials and charged particle trajectories in and around the source, and vacuum chamber measurements of the emitted ion beam. Once the ion source is understood, it is successfully used to test a typical ion instrument. Further aspects of the ion source, efficiency, thermionic filament emission, and collision frequencies are also discussed. / Doctor of Philosophy / Satellites have become a critical resource for business and governments. The study of the high edge of the earth’s atmosphere, where satellites operate, is difficult because the physics of this region is so complex. More measurements of the upper atmosphere are needed to understand exactly how it works and improve the computer models simulating the atmosphere. The instruments used to measure this region need to be validated before they are launched. This dissertation describes the design and testing of an ion source device that can produce charged particles in a very low pressure environment, such as a vacuum chamber, to create conditions similar to those an instrument would encounter in orbit. Computer simulations and physical tests of the source are presented, compared, and found to match. Finally, an actual satellite instrument is successfully validated with the source.

Yes / This paper presents a simulation study of vacuum membrane distillation (VMD) for desalination. A simulation model was built on Aspen Plus® platform as user defined unit operation for VMD module. A simplified mathematical model was verified and the analysis of process performance based on simulation was also carried out. Temperature and concentration polarization effects are significant in the conditions of higher feed temperature and/or vacuum pressure. The sign of difference of the vapour pressures between at the membrane interfaces, is a pointer of the vacuum pressure threshold. Increasing the vacuum pressure at lower feed temperature is an effective way to increase the permeate flux and reduce the energy consumption simultaneously.

<p>Istraživanja u okviru disertacije usmerena su na razvoj vakuumskog postupka su&scaron;enja voća. Konstruisan je prototip laboratorijske vakuumske su&scaron;are i optimizovan proces su&scaron;enja vi&scaron;anja i borovnica. U cilju optimizacije procesa su&scaron;enja ispitan je uticaj nezavisno promenljivih procesa, temperature i pritiska, na parametre kvaliteta osu&scaron;enog voća (aktivnost vode, sadržaj ukupnih fenola, ukupnih monomernih antocijana i vitamina C, antioksidativnu aktivnost, promenu boje, teksturu i sposobnost rehidratacije). Proces su&scaron;enja optimizovan je kori&scaron;ćenjem metode odzivnih povr&scaron;ina (engl. Response Surface Methodology, RSM).<br />Rezultati istraživanja pokazuju da tehnika su&scaron;enja voća u vakuumu daje odlične rezultate u pogledu očuvanja visokovrednih komponenata voća i ima perspektivu za &scaron;iru primenu u zanatskim i poluindustrijskim postrojenjima.</p> / <p>Research in the framework of the thesis focuses on the development of fruit vacuum-drying process. Laboratory vacuum dryer prototype was constructed. Cherries and blueberries vacuum drying process was optimized. In order to optimize the drying process, the influence of independent variables of the process (temperature and pressure) on the quality parameters of dried fruit (water activity, total phenol content, total monomeric anthocyanins and vitamin C, antioxidant activity, colour change, texture, and rehydration capability) was investigated. The drying process was optimized using Response Surface Methodology (RSM).<br />There is the possibility of application of the results in plants at semi-industrial and industrial level.</p>

Capacitance manometer with sensors maintained at temperatures above the temperature of the vacuum vessel may read a higher gas pressure than the true value. This arises due to a transport process of molecules induced by molecule-surface collisions called thermal transpiration effect. Thermal transpiration effect depends on the pressure, the temperature gradient, gas, geometry and surface properties of the interconnecting pipe between the capacitance manometer and the vacuum vessel. To determine the height of the thermal transpiration effect for the biomolecular gas tetrahydrofuran, an experimental setup has been built. Its suitability to measure the thermal transpiration effect has been tested. Measurements of thermal transpiration effects for nitrogen and tetrahydrofuran have been analyzed with the semi-empirical Takaishi-Sensui equation. The coefficients of the Takaishi-Sensui equation can be used to determine the magnitude of the thermal transpiration effect for different temperature gradients, diameters of the interconnecting pipe and pressures.

Ce travail présente l’étude d'une méthode de recherche utilisable en milieu industriel dessources de contamination chimique des pompes à vide équipant les lithographes EUV. Cetravail porte sur la problématique d’une éventuelle contamination carbonée introduite par lesystème de pompage et, notamment, par la turbine et le stator.A partir d’une caractérisation détaillée par chromatographie et spectroscopie dephotoémission de la contamination résiduelle issue du procédé de production, une procédured’analyse par spectrométrie de masse en phase gazeuse (RGA) utilisable en milieu industriel aété mise en oeuvre. En particulier, la possibilité de varier la température de l’échantillonpendant la mesure permet de caractériser la contamination carbonée résiduelle en étudiant lesprocédés physico-chimiques qui en sont à l’origine.Après avoir démontré l’efficacité du nettoyage final à éliminer les résidus des huiles de coupet avoir identifié la contamination organique résiduelle comme résidu du seul procédé denettoyage industriel, une copie « in vitro » de ce nettoyage a été développée : cela a permis demieux le caractériser en étudiant l’impact de plusieurs paramètres.L’influence de la concentration de lessive et de la procédure de séchage sur la contaminationcarbonée résiduelle a ainsi été étudiée. Une analyse de la contamination en phase gazeuse(RGA et TD-GCMS) ainsi qu’une caractérisation XPS de la surface des échantillons ont étéfaites. L’analyse de l’ensemble de ces résultats a permis d’établir un lien direct entre laconcentration de lessive utilisée et la contamination organique résiduelle. De plus,l’importance d’un séchage à haute température a été démontrée en mettant en évidence laprésence de plusieurs facteurs qui contribuent à la contamination résiduelle. / This work presents the study of a research method of the contamination sources of EUVLturbo molecular pumps, suitable for the industrial environment. This study deals with theproblem of a possible carbon contamination due to the pumping system and in particular tothe rotor and the stator.After a detailed characterisation of the production process residual contamination by TDGCMS/FID and XPS, a RGA procedure suitable for industrial environment has beendeveloped. The possibility to change the sample temperature during the measure lets tocharacterise the residual carbon contamination by investigating its primal physic-chemicalphenomena.The identification of the whole production process residual contamination demonstrates theefficacy of the industrial cleaning step to clean lubricants residuals. In order to bettercharacterise the cleaning step residual contamination, we developed an “in vitro” copy of theindustrial cleaning step.Thanks to the temperature variable RGA analysis of the residual contamination, we couldpoint out several contributions to carbon contamination and we could connect thesecontributions to different cleaning parameters.Detergent concentration as well as different drying procedure impact on residual carboncontamination has been studied. RGA and TD-GCMS/FID analysis as well as XPS surfacecharacterization have been performed. These analyses show a direct connection between thedetergent concentration used in the cleaning step and the residual carbon contamination.Furthermore, the importance of a high temperature drying step has been demonstrated.

This sequential study explores the perceptions of older adults and careworkers in Sweden regarding the benefits and challenges of smart vacuumcleaners. With a rapidly ageing population, understanding attitudes towardsthe use of such technology becomes essential. A mixed-methods approach,including questionnaires and semi-structured interviews, was used to gatherdata and provide a detailed understanding of the perceived benefits andchallenges associated with these devices. Findings suggest that older adultsperceive smart vacuum cleaners as beneficial in reducing cleaning assistancedependence and enhancing life quality. Concerns centred around affordabilityand fear for social isolation. Care workers saw potential for time-saving,leading to improved care. Despite some reservations, both groups recognizedthe potential benefits of smart vacuum cleaners. The study suggests the needfor larger, longitudinal studies to further explore these perspectives anddetermine the potential of smart vacuum cleaners in supporting ageing inplace.

Pneumatic vacuum systems are today used in automated manufacturing and packaging industries. Before an automated system is allowed to lift an object the control system has to get a good to go signal that informs that the desired vacuum level is reached in the gripper and that it is able to lift the object. The device sending this signal is called a vacuum switch. To reduce the energy consumption of the system the vacuum switch should also send a signal to the energy saving system. The work is conducted for Piab AB in Täby in Sweden. The purpose of this master thesis was to dimension and design a new electromechanical vacuum switch that is able to send a signal from two vacuum levels. The two levels should be adjustable but also dependent of each other to make the switch more reliable. The work resulted in an electromechanical vacuum switch with two dependent and adjustable signals. The switch met 13 of the 15 tested requirements. One of the requirements it failed to meet was the height requirement and the other was a performance parameter which it marginally failed. Further more, all requirements could not be verified. A full verification will have to be done with a later prototype. More work has to be done on the switch before it meets all the requirements and functions as desired, but the purpose can be considered fulfilled since all the basic functions are working as desired. / Pneumatiska vakuumsystem används idag inom automatiserade industrier. Innan ett automatiserat system är tillåtet att lyfta ett objekt måste kontrollsystemet få en OK signal som informerar om att den önskade vakuumnivån är uppnåd i gripdonet. Enheten som skickar OK signalen kallas en vakuumvakt. För att hålla nere på systemets energikonsumtion ska vakuumvakten även skicka en signal till energisparsystemet. Arbetet är utfört på Piab AB i Täby i Sverige. Syftet med det här examensarbetet var att dimensionera och konstruera en ny elektromekanisk vakuumvakt som kan skicka en signal från två olika vakuumnivåer. Dessa två vakuumnivåer ska vara justerbara men också beroende av varandra för att göra vakuumvakten mer pålitlig. Arbetet resulterade i en elektromekanisk vakuumvakt med två justerbara och beroende av varandra vakuumnivåer. Vakten uppfyllde 13 av 15 testade krav. En av de krav den inte klarade av att uppfylla var höjdbegränsningen, det andra kravet missade vakten marginellt och det var ett prestandakrav. Alla krav kunde inte verifieras, en fullständig verifikation av de specifierade kraven bör göras med en senare prototyp. Mer arbete behöver läggas ner på vakten innan den uppfyller alla krav och fungerar som önskat, men syftet med arbetet kan fortfarande anses vara uppfyllt eftersom alla grundläggande funktioner fungerar som det är tänkt.

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