No description available.

No description available.

No description available.

No description available.

The statistical mechanics of a one-dimensional Ising model in thermal equilibrium is well-established, textbook material. Yet, when driven far from equilibrium by coupling two sectors to two baths at different temperatures, it exhibits remarkable phenomena, including an unexpected 'freezing by heating. These phenomena are explored through systematic numerical simulations. This study reveals complicated relaxation processes as well as a crossover between two very different steady state regimes which are found to be bistable within a certain parameter range. / Ph. D.

Call number: LD2668 .T4 1979 F54 / Master of Science

Detta arbete syftar till att undersöka hur blå-grön infrastruktur kan användas som en metod för översvämningsskydd vid hamnomvandlingar av industriområden som en del i att öka städers resilience. Forskningsdesignen som används är en fallstudie av fenomenen blå-grön infrastruktur och urban flooding. Arbetets teoretiska ramverk utgörs av non-equilibrium-paradigmets syn på begreppet resilience. Resilience definieras här som ett system som påverkas av externa och interna processer samtidigt som det har en förmåga till kontinuerlig anpassning samt en fortlöpande funktionalitet. Av arbetets analys framkommer att vid implementering av blå-grön infrastruktur är helheten större än summan av delarna. Det är därför centralt att alla delar av det blå-gröna infrastruktursystemet fyller en funktion i sig själva så väl som i förhållande till varandra. Detta är den viktigaste aspekten som måste uppfyllas om blå-grön infrastruktur ska kunna möta de krav som urban flooding och havsnära exploatering ställer. / This studie aim to investegate how blue-green infrastructure can be used as a method for urban flood-prevention in redevelopments of former harbors as a part of increasing the resilience capacity of urban areas. The method is a case study of the fenomenon blu-green infrastructure and urban flooding. The studies theoretical framework is the non-equilibrium paradigm view of resilience. In this studie resilience is viewed as a system that is influenced by internal and external processes as well as retaining the capacity of constant adaptation and functionality.  As a result of the studies analysis it is shown that when implementing blue-green infrastructure the idea of that the whole is bigger than total of the parts is vital. The system that aims to cope with urban flooding has to be functional as a cohesive system as well as in the separate parts. This is the most important idea if blu-green infrastructure is to be useful in coping with the consequences of urban flooding as well as ensuring a more resilient future.

Two new apparati have been developed to measure solid-liquid and liquid-liquid equilibria via a synthetic visual method by determination of thermal signatures. One apparatus adopts a technique of using Peltier modules for cooling, and the other is a well-known design that uses a cryogenic fluid in a thermostatted glass cell for cooling of the sample. The Peltier design is for small sample volumes, with a 10 cm3 aluminium equilibrium cell and has a minimum operating temperature of 253.15 K. The glass design is developed to complement the Peltier and has a larger volume of 140 cm3 and a minimum operating temperature of 223.15 K. Both apparati have been semi-automated in order to increase the accuracy and improve the efficiency of data measurements. Therefore the experimenter no longer has to wait for many hours for the determination of equilibrium. This was done by incorporating software, which was specially designed for the apparati using Labview8TM, for controlling the cooling and heating rates. The uncertainty of the temperature measurements was found to be ±0.03 K for the Peltier apparatus and ±0.02 K for the Glass apparatus. Liquid-liquid equilibria data has also been measured on the Peltier apparatus, to demonstrate its versatility. This was done using a digital camera, controlled through the Labview software to identify cloud points. The results have been found to be comparable with literature values. For solid-liquid equilibria new systems of n-alkyl carboxylic acid binary mixtures have also been measured: heptanoic acid + butyric acid and heptanoic acid + hexanoic acid. These systems were measured using both apparati and both systems exhibited eutectic behaviour. All eutectic temperatures were measured on the Glass apparatus. Experimental data for these systems was modelled using the local composition models: Wilson, NRTL and UNIQUAC models. The NRTL model was found to give the best results for both systems with root mean square deviations (RMSD) of 2.16 K and 1.27 K and absolute average deviations (AAD) of 0.61 K and 0.49 K, between temperature measurements of this work and those calculated from the models, for the heptanoic acid + butyric acid and heptanoic acid + hexanoic acid systems, respectively. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2010.

The primary focus of this study is the measurement and modeling of binary and ternary VLE data. The measurements of binary and ternary systems were undertaken on a fully automated dynamic VLE apparatus. The glass dynamic VLE still was modified to handle pressures ranging from 0 to 500 kPa, however, the safest maximum pressure to which tests had been conducted was 350 kPa. Thus, this limit was not to be exceeded during the measurement of experimental data. The systems under investigation included the binary and ternary combinations of the following chemicals: n-hexane, 1-hexene and n-methyl-2-pyrrolidone (NMP) at isothermal conditions. A test system consisting of ethanol + cyclohexane was measured at 40 kPa, as well as the system of 1-hexene + NMP at 363.15 K and n-hexane + NMP at 363.15 K. Published literature data for these test systems were employed to verify the measured data for the test systems complied with thermodynamic consistency. All other data constitutes new data, currently unavailable in literature. The following isotherms were measured: 1) 1-hexene (1) + NMP (2) at 323.15, 343.15, 353.15 and 363.15 K 2) n-hexane (1) + NMP (2) at 353.15, 363.15, 378.15 and 383.15 K 3) 1-hexene (1) + n-hexane (2) at 343.15, 363.15 and 373.15 K, and 4) 1-hexene (1) +n-hexane (2) + NMP (2) at 363.15 K All system measurements were carried out on the glass low-to-medium pressure VLE still of Lilwanth (2011), with the exception of the test system ethanol + cyclohexane, which was carried out on the low pressure VLE glass still of Hirawan (2007). The two VLE stills, utilized to carry out measurements in this work, can operate isobarically and isothermally. The temperature on the stills of Hirawan (2007) and Lilwanth (2011) were controlled to within ±0.425 and ±0.089 K respectively and the accuracy of pressure control is to within ±0.320 and ±0.440 kPa respectively. In addition, for the calibration of the various systems: ethanol + cyclohexane, 1-hexene + NMP, n-hexane + NMP, 1-hexene + n-hexane and 1-hexene + n-hexane + NMP, the accuracies are: ±0.002, ±0.0034, ±0.0033, ±0.0066 and ±0.0083 of a mole fraction respectively. The binary interaction parameters obtained from modeling the three binary systems were used to predict the ternary system data. Thereafter, the experimentally measured data for the ternary system was then compared to the model prediction, which was completed on Dortmund Data Bank (DDB, 2011). The measured binary data was regressed utilizing the combined and the direct methods. For the direct method, the cubic equations of state (CEoS) used to describe the vapour phase included the Peng-Robinson (1976) and Soave-Redlich-Kwong (1972) equations combined with the mixing rule of Wong and Sandler (1992) in conjunction with the Gibbs excess energy models, namely the NRTL (1968) and UNIQUAC (1975) models, to describe the liquid phase non-idealities. For the combined method, the Gibbs excess energy activity coefficient models mentioned above were employed to represent the liquid phase imperfections and the vapour phase nonidealities were represented by cubic equations of state, as mentioned above, as well as the Hayden and O‟Connell (1975) virial equation of state for the calculation of the virial coefficients. To verify whether the measured data is thermodynamically consistent the point and direct tests were applied. Even though the direct test is a more stringent approach to testing thermodynamic consistency, for the systems 1-hexene + NMP and n-hexane + NMP, the point test was utilized as the primary means by which to quantify the data, as the associative effects of the NMP molecule effect the results obtained. For the system 1-hexene + n-hexane the direct test was used as the primary means to test the consistency of data, as no cross- or self-association is present. After extensive modeling was carried out, it was found that for the systems 1-hexene + NMP and n-hexane + NMP the model which enabled the best fit of the experimental data are the NRTL activity coefficient model in conjunction with the Hayden and O‟Connell virial equation of state (EoS). For the system 1-hexene + n-hexane the overall best fit model is the Peng-Robinson EoS in conjunction with the Wong-Sandler mixing rule and the NRTL activity coefficient model. A single set of binary interaction parameters for each of the three binary systems was obtained (via regression on Aspen Plus®) using the NRTL-HOC models. However, since Aspen Plus® cannot predict ternary system behaviour using the binary interaction parameters of the constituent systems, DDB was utilized. Further, DDB did not have available the HOC virial EoS (for enabling predictions), thus, it was decided to use the ideal gas model for representation of the vapour phase in conjunction with the NRTL activity coefficient model. The use of the ideal gas model does not compromise the integrity of the prediction in any way since the ternary system measurements were carried out in the dilute NMP region. Thus, since the main components in the ternary mixture at any one instant were 1-hexene and nhexane, and these components behave ideally, the ideal gas model is applicable. After the predicted behaviour for the ternary system was compared to the experimental data for the same system, the maximum percentage error encountered between the two data sets is 5%. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2012

No description available.