Recently, atomically thin two-dimensional (2D) transition metal dichalcogenides (TMDCs) materials have drawn significant attention due to their unique optical and electrical properties1, 2. This offers unique opportunities for the next-generation electronic and optoelectronic devices3. Specifically, recent innovations in the big-data-driven prediction of new 2D materials, integration of new device architectures, interfacial engineering of contacts between semiconductor/metals and semiconductor/dielectrics as well as encapsulation in hexagonal boron nitride4, 5 have further propelled the electrical mobility to be on a par with or even beyond the silicon (Si) counterpart. These strategies hold tantalizing prospects on extending the Moore's law. Yet, there is still room for improvement before 2D TMDCs become truly technologically relevant. The challenge lies in the full validation of the intrinsic charge transport that is associated with the specific nature and ordered arrangement of atoms in the atomically thin crystal lattice. This requires, the controlled stitch of both metals and chalcogenides in an atom-by-atom fashion. To this end, a variety of synthetic approaches have been developed, this includes but not limited to chemical vapor deposition (CVD) 6, 7, mechanical exfoliation8 and solution-based exfoliation9. Among which, CVD shows better controllability over thicknesses, geometric shapes, sizes, and qualities through manipulation of the growth factors, e.g., growth temperature, pressure, precursor ratio, and gas carrier. These complex growth environments will significantly confound the scalability, crystallinity, defect density, and reproducibility of the CVD approach. Therefore, an impetus exists to gain fundamental insights into the universal growth mechanism that is currently lacking and therefore curbs the realization o the controlled epitaxy of high-mobility three-atom-thick semiconducting TMDCs films with wafer-scale-homogeneity. In this thesis, a mechanistic study toward revealing the epitaxy growth mechanism is established to include 1) epitaxy growth of multilayer, 2) epitaxy growth of heterostructures, and 3) epitaxy growth of high quality (exceedingly low defect density) of 2D TMDCs materials through a controlled CVD strategy.

<p>Dynamic modeling of Vapor Compression Cycles (VCC) is particularly important for designing and evaluating controls and fault detection and diagnosis (FDD) algorithms. As a result, transient modeling of VCCs has become an active area of research over the past two decades. Although a number of tools have been developed, the computational requirements for dynamic VCC simulations are still significant. A computationally efficient but accurate modeling approach is critically important to accelerate the design and assessment of control and FDD algorithms where a number of iterations with a variety of test input signals are required. Typically, the dynamics of compressors and expansion devices evolve on an order of magnitude faster than those of heat exchangers (HX) within VCC systems. As a result, most dynamic modeling efforts have focused on heat exchanger models. The switched moving boundary (SMB) method, which segments a heat exchanger depending on thermodynamic phase of the refrigerant, i.e. subcooled liquid, two-phase and superheated vapor, and moves control volumes as the length of each phase changes, can reduce the computation time compared with the finite volume (FV) method by solving fewer equations due to a smaller set of control volumes. Despite the computational benefit of the SMB, there is a well-known numerical issue associated with switching the model representations when a phase zone disappears or reappears inside of a heat exchanger. More importantly, the computational load is still challenging for many practical VCC systems. This thesis proposes an approach applying nonlinear model order reduction (MOR) methods to dynamic heat exchanger models to generate reduced order HX models, and then to couple them to quasi-static models of other VCC components to complete a reduced order VCC model. To enable the use of nonlinear model reduction techniques, a reformulated FV model is developed for matching the baseline MOR model structure, by using different pairs of thermodynamic states with some appropriate assumptions. Then a rigorous nonlinear model order reduction framework based on Proper Orthogonal Decomposition (POD) and the Discrete Empirical Interpolation Method (DEIM) is developed to generate reduced order HX models. </p><p> </p><p> The proposed reduced order modeling approach is implemented within a complete VCC model. Reduced order HX models are constructed for a centrifugal chiller test-stand at Herrick Labs, Purdue University, and are integrated with quasi-static models of compressor and expansion valve to form the complete cycle. The reduced cycle model is simulated in the Modelica-based platform to predict load-change transients, and is compared with measurements. The validation results indicate that the reduced order model executes 200 times faster than real time with negligible prediction errors.</p><br>

Water scarcity has caused severe impact on the entire ecosphere while the climate change is resulting in high frequency of extreme weather conditions, especially extended period of drought. Due to the even increasing world’s population and the continued societal modernization, water scarcity is now one of the leading global challenges towards the development of human society. On the other hand, atmospheric water, accounting for 6 times the water in all rivers on Earth, is emerging as an alternative water resource. This dissertation thoroughly investigated the fully solar energy driven atmospheric water harvesting (AWH) process in a broad scientific and application context. The light-to-heat conversion process of solar photothermal materials was investigated first with a rationally designed droplet-laser system, which in combination with the calculation of heat of absorption of water vapor for various application scenarios, formed a theoretical basis of this dissertation research. As a result, a series of commonly used hydrated salts and their anhydrous counterparts were judiciously selected and successfully proven to be low-cost AWH materials to generate clean fresh water for arid regions. A hydrogel-deliquescent salt composite was further developed as AWH material with a significantly enhanced fresh water production capacity. A new design of nano-capsule encapsulated deliquescent salt was further put forward to enhance water vapor sorption/desorption kinetics, which enabled, for the first time, multiple sorption/desorption cycles within one day and thus multiplied water production capacity. The first-ever continuous AWH device, as opposed to batch-type one, was rationally designed, fabricated, and successfully tested in field conditions outdoors. At last, the dissertation pioneered a novel concept of atmospheric water sorption and desorption cycle for photovoltaic (PV) panel cooling. This dissertation shines significant light on sorption based atmospheric water harvesting and inspires more research efforts on this important research topic.

Carbon nanotube forests (CNTFs) are grown using an injection chemical vapor deposition method. Images of CNTFs are taken using a scanning electron microscope and are used to measure their height and density. Growth parameters are systematically varied to determine their effect on the height and density of CNTFs. Investigations of CNTF density as a function of distance from the growth substrate reveal that diffusion can be a limiting factor on CNTF growth. Our findings indicate that height and density are related and that each growth parameter has multi-dimensional effects.

Intermolecular complexes between H₂O and atmospheric species HO, HO₂, H₂O₂, O₃, NO and NO₂ have been studied by ab initio molecular orbital methods. The studies have been performed to the MP2 theory level by using 4-31G, 6-31G, D95, 6-31G**, D95**, 6-311G**, 6-311+G**, 6-311++G**, 6-311+G(2d,lp) and 6-311+G(2d,2p) basis sets. The geometries were fully optimized. The vibrational frequencies were calculated. The Basis Set Superposition Error (BSSE) were estimated. Finally, the binding energies of the complexes were predicted with other thermochemical properties. The binding energies of H₂O•HO, H₂O•HO₂, H₂O•H₂O₂, H₂O•O₃, H₂O•NO and H₂O•NO₂ are estimated to be 5.7±0.6, 8.9±1.0, 7.3±1.3, 1.8±0.2, 1.17 (no BSSE correction) and 2.98 (no BSSE correction) Kcal/Mol, respectively. The Kcq for dimerization to yield H₂O•HO, H₂O•HF, H₂O•HO₂, H₂O•H₂O and H₂O•H₂O₂ are estimated to be 0.11, 2.8, 3.3, 0.067 and 0.11 atm¯¹, respectively. The H₂O•HO, H₂O•HF, H₂O•HO₂, H₂O•H₂O and H₂O•H₂O₂ are quite strongly bonded complexes, while H₂O•O₃, H₂O•NO and H₂O•NO₂ are only weakly bonded complexes. The Kcq changes with temperature are discussed, and their importance in atmospheric chemistry are addressed.

Publicación a texto completo no autorizada por el autor. / Aborda el estudio de una nueva tecnología para el aislamiento de aceites esenciales, que permite remover sus componentes volátiles de interés comercial. La materia prima de ensayo fue la semilla triturada de Schinus molle L. (SML), elegida por su alto contenido de aceite esencial (EO), su disponibilidad y una variedad de aplicaciones. El dispositivo experimental fue diseñado e implementado por el autor haciendo uso de materiales y dispositivos disponibles localmente. Los resultados remarcables indican que la tecnología de vapor (PST) aumenta en 45% el rendimiento alcanzado con arrastre de vapor (SST). En resumen, el estudio implica el modelado matemático de cada una de las tres etapas en las que fue dividido el proceso para su análisis, los que fueron validados a la luz de los datos experimentales utilizando herramientas estadísticas y de simulación, develando así una tecnología limpia de separación intensificada que puede sustituir exitosamente al clásico proceso de arrastre de vapor. / Tesis

In this thesis,zirconium carbide (ZrC) layers were deposited on graphite substrates using a CVD reactor at temperatures ranging from 1250 °C to 1450 °C in steps of 50 °C. The deposited layers were characterised by XRD, Raman Spectroscopy and SEM.ZrCsamples were also prepared by spark plasma sintering (SPS), at 1700, 1900 and 2100 °C at 50 MPa for 10 minutes. The phase and microstructure after the sintering process were investigated by XRD and SEM. Iridium (Ir) thin films were deposited on these ZrCsamples and annealed in vacuum at temperatures of 600 and 800 °C for 2h. The phase composition, solid-state reactions and surface morphology were investigated by GIXRD and SEM. XRD was used to identify the phases present in the as-deposited and annealed samples. It showed that Ir2Zr was the initial phase formed at 600 °C. At temperature 800 °C IrZr formed. / Thesis (PhD (Physics))--University of Pretoria, 2019. / University of Pretoria / Physics / PhD (Physics) / Unrestricted

Tesis por compendio / Fish salting and smoking industry need to innovate in their production processes, optimizing them to increase the profitability of its activities, improving the nutritional quality of their products and ensuring food safety. Currently, salting and smoking improvements focus primarily on speed up processes, using alternative techniques, which allow reducing processing steps, minimize waste and achieve a greater standardization of their products. In this study, a simultaneous salting-smoking method has been developed, employing a controlled salting, liquid smoke and water vapour permeable bags, to obtain smoked fish products. The feasibility of this technique was studied on three fish species (salmon, cod and trout), with a view to optimizing processing conditions, according to the characteristics of the raw material and the commercial products used as a reference. Afterwards, the quality and shelf-life during cold storage of the products obtained was evaluated. In the next step, the nutritional quality of salmon and trout products developed was improved, by means of the partial replacement of NaCl by other salts, and the effect on the physicochemical and sensory characteristics, as well as the quality and shelf-life during storage was evaluated. Finally, the application of impedance spectroscopy as an on-line monitoring technique on the salting-smoking was studied. The results show that the simultaneous salting-smoking in water vapour permeable bags is suitable to obtain smoked fish products, with similar characteristics to the commercial products, without affecting consumer acceptance, and microbiologically stable during storage. The new method offers advantages compare with the traditional methods such as the reduction of processing steps, less brine waste, and the protection against contaminations during processing. In the present study, replacement of 50% NaCl by KCl has been achieved in the smoked salmon and trout products, whithout affecting physicochemical and sensory quality or the microbial stability during cold storage. The spectroscopy impedance has shown to be an effective tool in the on-line monitoring of the physicochemical parameters in the salting-smoking. / La industria de los salazones y ahumados de pescado necesita innovar en sus procesos productivos, optimizando los mismos para rentabilizar sus actividades, mejorando la calidad nutricional de sus productos y garantizando la inocuidad de los mismos. En la actualidad, la mejora de los procesos de salado y ahumado se centra principalmente en agilizar los procesos, aplicando nuevas técnicas alternativas que permitan reducir los tiempos de procesado, minimizar la generación de residuos y conseguir una mayor estandarización de sus productos. En el presente trabajo se ha desarrollado un nuevo método de salado-ahumado simultáneo, empleando un salado controlado, humo líquido y bolsas permeables al vapor de agua, para obtener productos de la pesca ahumados. La viabilidad de la técnica se estudió en tres especies de pescado (salmón, bacalao y trucha), con el fin de optimizar las condiciones de procesado, en función de las características de la materia prima y de productos comerciales de referencia. Posteriormente, se evaluó la calidad y vida útil durante el almacenamiento en refrigeración de los productos obtenidos. En la siguiente etapa, se llevó a cabo una mejora en la calidad nutricional de los productos desarrollados de salmón y trucha ahumada a través de la reducción de su contenido en sal, mediante el reemplazo de NaCl por otras sales y se estudió su efecto sobre los parámetros fisicoquímicos y sensoriales, así como en la calidad y vida útil durante su almacenamiento. Finalmente, se estudió la aplicación de la técnica de espectroscopía de impedancia como herramienta de monitorización on-line del proceso de salado-ahumado de salmón. Los resultados obtenidos han demostrado que el salado-ahumado simultáneo en bolsas permeables al vapor de agua permite obtener productos de pescado ahumado con características similares a los productos comerciales, sin afectar a su aceptación por parte del consumidor y estables microbiológicamente durante el almacenamiento. El nuevo método aporta ventajas respecto a los procesos tradicionales de ahumado, como son la reducción de etapas de procesado, la disminución de residuos de salmuera y la protección del producto frente a contaminaciones durante el procesado. En el presente estudio, se ha conseguido sustituir un 50% de NaCl por KCl en el producto de salmón y trucha ahumada sin afectar a la calidad físico-química y sensorial, ni a la estabilidad microbiológica durante su almacenamiento en refrigeración. La técnica de espectroscopía de impedancia ha demostrado ser una herramienta eficaz en la monitorización on-line de los parámetros fisicoquímicos que caracterizan el salado-ahumado de salmón. / La indústria de les saladures i fumats de peix necessita innovar en els seus processos productius, optimitzant els mateixos per a rendibilitzar les seues activitats, millorant la qualitat nutricional dels seus productes i garantint la innocuïtat dels mateixos. En l'actualitat, la millora dels processos de salat i fumat se centra principalment a agilitzar els processos, aplicant noves tècniques alternatives que permeten reduir els temps de processat, minimitzar la generació de residus i aconseguir una major estandardització dels seus productes. En el present treball s¿ha desenvolupat un nou mètode de salat-fumat simultani, emprant un salat controlat, fum líquid i bosses permeables al vapor d'aigua, per a obtindre productes de la pesca fumats. La viabilitat de la tècnica es va estudiar en tres espècies de peix (salmó, abadejo i truita), a fi d'optimitzar les condicions de processat, en funció de les característiques de la matèria prima i de productes comercials de referència. Posterioment, es va avaluar la qualitat i vida útil durant l'emmagatzemament en refrigeració dels productes obtinguts. En la següent etapa, es va dur a terme una millora en la qualitat nutricional dels productes desenvolupats de salmó i truita ahumada a través de la reducció del seu contingut en sal, per mitjà del reemplaçament de NaCl per altres sals i es va estudiar el seu efecte sobre els paràmetres físico-químics i sensorials, així com en la qualitat i vida útil durant el seu emmagatzemament. Finalment, es va estudiar l'aplicació de la tècnica d'espectroscòpia d'impedància com a ferramenta de monitorització on-line del procés de salat-fumat de salmó. Els resultats obtinguts han mostrat que el salat-fumat simultani en bosses permeables al vapor d'aigua permet obtindre productes de peix fumat, amb característiques semblants als productes comercials, sense afectar la seua acceptació per part del consumidor i estables microbiològicament durant l'emmagatzemament. El nou mètode aporta avantatges respecte als processos tradicionals de fumat, com són la reducció d'etapes de processat, la disminució de residus de salmorra i la protecció del producte davant contaminacions durant el processat. En el present estudi, s'ha aconseguit substituir un 50% de NaCl per KCl en el producte de salmó i truita ahumada sense afectar la qualitat físico-química i sensorial, ni a l'estabilitat microbiològica durant el seu emmagatzemament en refrigeració. La tècnica d'espectroscòpia d'impedància ha demostrat ser una ferramenta eficaç en la monitorització on-line dels paràmetres fisicoquímics que caracteritzen el salat-fumat de salmó. / Rizo Párraga, AM. (2017). DESARROLLO Y OPTIMIZACIÓN DE NUEVOS PROCESOS PARA LA OBTENCIÓN DE PRODUCTOS DE LA PESCA AHUMADOS [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/77994 / TESIS / Premios Extraordinarios de tesis doctorales / Compendio

京都大学 / 0048 / 新制・課程博士 / 博士(エネルギー科学) / 甲第20097号 / エネ博第344号 / 新制||エネ||69(附属図書館) / 33213 / 京都大学大学院エネルギー科学研究科エネルギー社会・環境科学専攻 / (主査)教授 坂 志朗, 教授 髙野 俊幸, 准教授 河本 晴雄 / 学位規則第4条第1項該当 / Doctor of Energy Science / Kyoto University / DGAM

In the past few decades, devices such as computers have become smaller, and their performance has improved beyond comparison. Semiconductors and interconnectors are used in almost all devices today and are made of thin films. Chemical vapor deposition (CVD) and atomic layer deposition (ALD) are common methods for depositing conformal films, where the film grows by being exposed to precursors either continuously as in CVD or by pulses as is pulsed CVD and ALD. It has been reported that Cu amidinate and guanidinate are precursors for depositing metallic Cu (Copper), but they tend to decompose. Precursors that are thermally stable and can be used to deposit a thin film of Cu are (1,3-di-tert-butyltriazenides) copper(I) (Cu-triazenides). This precursor has been synthesized and developed by the Pedersen Group in the Department of Physics, Chemistry, and Biology (IFM) at Linköpings University. This thesis investigates if Cu-triazenides are suitable as vapor deposition precursors using pulsed CVD and if Cu-triazenides are suitable as an ALD precursor with H2O as the second precursor. The main objective of this thesis is to focus on films deposited with ALD by finding the ALD window that gives a growth per cycle and making a saturation curve for each precursor. Si(100) and glass were used as the substrate, and SEM-EDX (Scanning electron microscopy- Energy- dispersive X-ray spectroscopy), XRD (X-ray diffraction), and XRR (X-ray reflectivity) analyzed the chemical, physical and, optical properties of the films. The Cu-triazenides were suitable as single-source precursors, as films were deposited with pulsed CVD on both Si(100) and glass. ALD deposited no film on Si(100) between the temperature 175–300 °C, and the analysis methods did not provide information on the thickness and composition of the films deposited on the glass.