Discussion of the application of mathematical softwares for the determination of frequency characteristics of mechanical systems

There are many large-scale contacting methods for gas reactions requiring a solid catalyst. The catalytic gas-solid Fluidized Bed Reactor (FBR) is one of the popular methods in industry. In FBRs the bulk of the gas throughput is present as lean bubbles, mostly deprived of solids, bubbling through a solids-rich emulsion phase. The movement of gas into and out of the emulsion often dictates the performance of an FBR. During the past five decades major contributions have been made towards the understanding of FBRs, although numerous gaps still exist, especially at higher bubbling regime velocities. This work follows an integrated approach for the simultaneous measurement of hydrodynamics and reactor performance. Hydrodynamics are measured using fast X-Ray Tomography (XRT), pressure analysis techniques and an optical fibre probe. Reactor performance is measured by utilizing the ozone decomposition reaction. Performance is quantified using a basic two-phase reactor model with an apparent overall interphase mass transfer (K0) parameter. Two 14 cm (ID) fluidized bed columns are used, one setup supporting the ozone decomposition reaction and the other installed within a fast XRT facility. Special emphasis is placed on superficial velocities (U0) spanning the entire bubbling regime up to the onset of the turbulent regime (Uc). The particle types employed are Geldart B sand particles and highly dense ferro-silicon (FeSi) particles. Fines are added to both particle types, resulting in a total of four particle systems (sand baseline; sand with fines; FeSi baseline; FeSi with fines). Time constraints on the XRT equipment limited the tomography measurements to the sand baseline particle system. The hydrodynamics of the other particle systems were limited to the pressure signal and optical probe measurements of the ozone decomposition setup. The results of the sand baseline system suggest that a distinction should be made between the low-interaction bubbling regime and the high-interaction bubbling regime. A change in mass transfer behaviour occurs around a U0/Uc value of 0.25. Reactor performance increases up to U0/Uc = 0.7, after which a decreasing trend is observed. An empirical correlation is proposed for the specific interphase mass transfer (kbe) of the higher velocity bubbling regime. This correlation is based on the integration of the hydrodynamics determined by means of XRT and reactor performance: 4-12 The hydrodynamic parameter β gives the best fit for the entire velocity range with an average error of 8%, although it is not recommended for U0/Uc<0.17. It is observed that the classical approach of penetration theory for interphase mass transfer, performs exceptionally well at low velocities (U0/Uc<0.34). The addition of fines to the FeSi particle type decreases the overall reactor performance, despite decreased bubble sizes. The solids fraction, however, unexpectedly increases with the addition of fines and a collapse of the emulsion phase is measured. It is therefore postulated that though flow in the emulsion phase is much higher for the FeSi baseline system and decreases with the addition of fines. For the sand particle type, the behaviour expected from literature is observed: reactor performance increases, bubble sizes decrease and the solids fraction decreases. Very distinct hydrodynamic behaviour is observed for all the fluidization regimes with XRT. Probability density distributions show there are still two phases present in the turbulent regime and that the emulsion-phase solids fraction remains independent of velocity until fast fluidization sets in. The turbulent regime has unique hydrodynamic behaviour, although voids appear to be a transient structure between the structures of the bubbling and fast fluidization regimes. / Thesis (PhD)--University of Pretoria, 2013. / gm2014 / Chemical Engineering / unrestricted

Ulvsunda is a former industrial area in Stockholm facing a politically uncertain future. The intention of the project is to explore what developing it under these very circumstances would imply. How do you design for uncertain futures? For time-limited use? In a first phase I looked at the densification of a block of land, and in a second phase the development of specific buildings. The response I propose are buildings general in their interior structure and at the same time very specific in their urban expression. Individual spaces are auctioned out repetitively over time according to a concept called ‘Solids’, responding to the demands on the area over time. / Ulvsunda är ett ’före detta’ industriområde i Stockholms som befinner sig i ett planeringsmässigt vacuum. Syftet med det här projektet är att undersöka vad en utveckling under just de förutsättningarna kan innebära. Hur designar man för en osäker framtid; för tidsbegränsad användning? I en första fas studerade jag förtätnings- och stadsrumsstrategier och i en andra fas utvecklades specifika byggnader. Mitt förslag innebär byggnader med en öppen intern struktur matchat med ett specifikt yttre. Användning tilldelas genom ett system av auktioner över tid enligt ett koncept som kallas ’Solids’, på så vis kan byggnaderna svara på platsens krav över tid.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Civil Engineering, 1981. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Bibliography: leaves 222-223. / by John Lambros Tassoulas. / Ph.D.

京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第21428号 / 農博第2306号 / 学位論文||H30||N5156(農学部図書室) / 京都大学大学院農学研究科地域環境科学専攻 / (主査)教授 近藤 直, 准教授 小川 雄一, 教授 飯田 訓久 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DGAM

Alterations of fluid phase transitions in porous materials are conventionally employed for the characterization of mesoporous solids. In the first approximation, this may be based on the application of the Kelvin equation for gas–liquid and the Gibbs–Thomson equation for solid–liquid phase equilibria for obtaining pore size distributions. Herein, we provide a comparative analysis of different phase coexistences measured in mesoporous silica solids with different pore sizes and morphology. Instead of comparing the resulting pore size distributions, we rather compare the transitions directly by using a common coordinate for varying the experiment’s thermodynamic parameters based on the two equations mentioned. Both phase transitions in these coordinates produce comparable results for mesoporous solids of relatively large pore sizes. In contrast, marked differences are found for materials with smaller pore sizes. This illuminates the fact that, with reducing confinement sizes, thermodynamic fluctuations become increasingly important and different for different equilibria considered. In addition, we show that in the coordinate used for analysis, mercury intrusion matches perfectly with desorption and freezing transitions.

Pharmaceutical solids tend to exist in different physical forms termed as polymorphs. Issues about pharmaceutical systems are mainly concerned with the active ingredient's physico-chemical stability and bioavailability. The main aim of this study is to investigate the non-bonded interactions in pharmaceutical solids that govern the physical pharmaceutics performance of such materials and through the use of structural techniques and correlation of these results with crystal structural database to establish the presence of physical motifs in selected systems. Structural motifs were identified by the use of single crystal and crystal packing analysis on diverse range of pharma-relevant materials including chalcones, cryptolepines, biguanides and xanthines. These selected systems were validated using functional group and molecular analysis and correlating them to the Cambridge Structural Database. Crystallization studies are done on these selected systems as well as exploiting those using synthetic analogues. A total of 51 crystal structures were investigated including 16 new structure determinations. Addition synthesis of new xanthines to investigate novel intermolecular patterns was also undertaken. The understanding and exploitation of intermolecular interactions involving hydrogen bonds and coordination complexation during packing can be used in the design and synthesis of solid state molecular structures with desired physical and chemical properties.

No description available.

Nuclear magnetic resonance (NMR) provides a variety of tools for the structural characterization of porous solids. In this paper, we discuss a relatively novel approach called NMR cryodiffusometry, which is based on a simultaneous assessment of both the phase state of intraporous liquids at low temperatures, using NMR cryoporometry, and their transport properties, using NMR diffusometry. Choosing two model porous materials with ordered and disordered pore structures as the host systems, we discuss the methodological and fundamental aspects of the method. Thus, with the use of an intentionally micro-structured mesoporous silicon, we demonstrate how its structural features give rise to specific patterns in the effective molecular diffusivities measured upon progressive melting of a frozen liquid in the mesopores. We then present the results of a detailed study of the transport properties of the same liquid during both melting and freezing processes in Vycor porous glass, a material with a random pore structure. 1

Vatten är en livsviktig resurs därför behöver kvalitén övervakas. Slamhalt i vatten är viktigt eftersom det kan föra med sig gifter och näringsämnen, men även grumlar vattnet vilket kan påverka livsmiljön för vattenlevande organismer. Slamhalt varierar över tid på grund av olika processer som transporterar material till vattendrag. För att mäta slamhalten har man historiskt tagit vattenprover i fält. Det är tidsödande och görs sällan vilket leder till att man lätt missar toppar och dalar i flödet.  Turbiditet är möjligt att mäta in situ och innebär att vattnets ljusgenomsläpplighet mäts. Det kan mätas med täta intervall vilket ger detaljerad information om förändringar i vattendragen. Korrelationen mellan turbiditet och slamhalt har undersökts flera gånger men eftersom mätningar reagerar på partiklars storlek och form behöver man utvärdera sambandet för varje enskilt vattendrag.  2017 gjordes en studie för Sveriges lantbruksuniversitet där Hoang (2017) använde multivariabel statistik för att undersöka turbiditet korrelerat med fosfor samt jordarters och markanvändnings påverkan på relationen i svenska vatten.  Sedan dess har markdata uppdaterats vilket gör det aktuellt att undersöka korrelationen mellan slamhalt och turbiditet. Genom linjär regression visades ett tydligt samband mellan turbiditet och slamhalt för många avrinningsområden. De högsta korrelationerna syntes för områden med hög fördelning av åkermark och lerhalt. / Water is a vital resource for life, that is why water quality is monitored. Suspended solids in water are important because it transports pollutants and nutrients, it also dims the water which can affect the environment for water living organisms. Suspended solids change over time due to different processes that transport materials to waterbodies. Historically, suspended solids have been measured by taking samples in the field. That takes a lot of time and fluctuations are lost because of dispersed measuring periods.  Turbidity can be measured in-situ and quantifies the light attenuation of the water. It can be measured with tight intervals which results in detailed information about changes in the waterbody. The correlation between suspended solids and turbidity has been studied several times, however, a turbidity sensor reacts to particle size and form which means that the correlation needs to be investigated for every individual waterbody.  2017 a study at the Swedish university of agriculture was done where Hoang (2017) used multivariate statistics to study turbidity correlated with phosphorus, as well as soil classes and land use factors influence on the relationship in Swedish waters. Since then, new data for soil and land use have been updated which makes it relevant to evaluate the correlation between suspended solids and turbidity. Through linear regression a clear correlation was shown for many catchments. The highest correlations were found in areas with high rates of agriculture and clay rich soils.