Risks management in the wine supply chain during the Global Pandemic

Treballs Finals del Màster en Oficial en Empresa Internacional / International Business, Facultat d'Economia i Empresa, Universitat de Barcelona. Curs: 2020-2022. Tutor: Xavier Rius PochThe COVID19 pandemic can be considered the worst global crisis since WorldWarII. No one predicted this sudden catastrophe and how it would last until now. In particular, it has greatly impacted companies engaged in import and export. This resear chaims to identify the wine supply chain risks and learn how the wineries mitigate the risks. Provide a reference for supply chain risk management for wineries and small and medium-sized exporters

Stable intermediate phase of secondary structures for semiflexible polymers

Systematic microcanonical inflection-point analysis of precise numerical results obtained in extensive generalized-ensemble Monte Carlo simulations reveals a bifurcation of the coil-globule transition line for polymers with a bending stiffness exceeding a threshold value. The region, enclosed by the toroidal and random-coil phases, is dominated by structures crossing over from hairpins to loops upon lowering the energy. Conventional canonical statistical analysis is not sufficiently sensitive to allow for the identification of these separate phases

Secondary-Structure Phase Formation for Semifelxible Polymers by Bifurcation in Hyperphase Space

Canonical analysis has long been the primary analysis method for studies of phase transitions. However, this approach is not sensitive enough if transition signals are too close in temperature space. The recently introduced generalized microcanonical inflection-point analysis method not only enables the systematic identification and classification of transitions in systems of any size, but it can also distinguish transitions that standard canonical analysis cannot resolve. By applying this method to a generic coarse-grained model for semiflexible polymers, we identify a mixed structural phase dominated by secondary structures such as hairpins and loops that originates from a bifurcation in the hyperspace spanned by inverse temperature and bending stiffness. This intermediate phase, which is embraced by the well-known random-coil and toroidal phases, is testimony to the necessity of balancing entropic variability and energetic stability in functional macromolecules under physiological conditions

Impact of bending stiffness on ground-state conformations for semiflexible polymers

Many variants of RNA, DNA, and even proteins can be considered semiflexible polymers, where bending stiffness, as a type of energetic penalty, competes with attractive van der Waals forces in structure formation processes. Here, we systematically investigate the effect of the bending stiffness on ground-state conformations of a generic coarse-grained model for semiflexible polymers. This model possesses multiple transition barriers. Therefore, we employ advanced generalized-ensemble Monte Carlo methods to search for the lowest-energy conformations. As the formation of distinct versatile ground-state conformations, including compact globules, rod-like bundles, and toroids, strongly depends on the strength of the bending restraint, we also performed a detailed analysis of contact and distance maps

Wind turbine designs for urban applications: A case study of shrouded diffuser casing for turbines

The increased demand for renewable energy and the development of energy independent building designs have motivated significant research into the improvement of wind power technologies that target urban environments. However, the implementation of wind turbines in urban environments is still very limited. There have been some studies analyzing different designs of urban wind turbines either using computational fluid dynamics (CFD), wind tunnel tests or field data for existing or new turbine designs. This paper reviews the state-of-the-art of urban wind energy by examining the various types of urban wind turbine designs, with a view to understand their performance and the synergy between the turbines and the urban environments. It also considers a flanged diffuser shroud mechanism - a fluid machine, mounted on rooftop of buildings used as casing for small wind turbines to improve turbine performance by using mainly CFD. The diffuser shroud mechanism can draw the airflow over buildings utilizing its special features such as, cycloidal curve geometry at the inlet and a vortex generating flange at the outlet, to guide and accelerate the airflow inside. The performance of the fluid machine is optimized parametrically. The mechanism is modeled on a building rooftop in a real test site in Montreal, Canada with real statistical wind data. The CFD result confirms the functionality of the fluid machine to take advantage of the airflow over buildings in complex built-environments for wind power generation

Passivation of GaAs surfaces and fabrication of self-assembled In(Ga)As/GaAs quantum ring structures

This work concentrates on two topics: (i) GaAs surface passivation methods using different materials and (ii) formation of InAs islands on GaAs and transformation of InAs islands into quantum rings (QRs). All the samples are fabricated by metalorganic vapor phase epitaxy and characterized by optical spectroscopy and atomic force microscopy. InGaAs/GaAs near-surface quantum well (NSQW) structures were used in the GaAs surface passivation studies because of their sensitivity to surface states. Ultra-thin InP, GaP, GaN layers were grown in-situ on top of the NSQW structure as the passivation layer. As-P and As-N exchange on the GaAs surface were also applied for passivation. In all the passivation methods, the photoluminescence (PL) intensities and carrier lifetimes of the NSQWs were significantly increased. The enhancement factor of the PL intensity was up to two orders of magnitude. The study of time durability of the passivation after keeping the samples for months in air ambient showed that those passivation methods protect the samples against oxidation while the unpassivated samples degrade severely. The passivation effects of these materials were also studied using NSQWs fabricated on (110)-oriented GaAs substrates. The suitability of atomic layer deposited (ALD) titanium nitride layer on GaAs surface as an ex-situ passivation layer was also investigated. Although the enhancement factor of the PL intensity is smaller than that obtained by in-situ methods, smooth surface morphology and notable extension of carrier lifetime were observed in the ALD passivated samples. It is known that island formation is severely suppressed on the GaAs (110) surface. This limitation can be overcome by using a thin strain reducing layer, e.g., an InGaAs layer. Relatively uniform InAs islands with an average areal density of 109 cm-2 were obtained on GaAs (110) substrate at 400 °C using a thin InGaAs strain reducing layer. Transformation of InAs islands into rings was realized by partially capping the InAs islands and annealing under tertiarybutylarsine flow. Effects of growth conditions on ring evolution were studied by varying the thickness of the partial capping layer, annealing time and annealing temperature. It was concluded that the temperature dependence of the diffusion anisotropy of the indium atoms plays an important role in the ring evolution. The annealing process of the partially capped islands affects significantly the ring shape and the optical properties of the QR structure

Selenium isotope systematics of mid-ocean-ridge basalts and implications for the long-term volatile and chalcophile record of the crust–mantle system

Selenium is a chalcophile, moderately volatile and redox-sensitive element. The Se isotopic and elemental systematics of mantle-derived rocks and melts may therefore provide new approaches to study the terrestrial volatile origin and evolution as well as secular changes of redox conditions across the surface and mantle reservoirs. Selenium is significantly depleted in mantle samples (at ng/g levels), posing analytical challenges for Se isotopic studies of the igneous system. This study presents an analytical protocol suitable for precise and accurate determination of Se isotope and Se–Te abundances of igneous rocks. The Se–Te elemental systematics provide a petrogenetic context for interpreting Se isotope systematics. The new method was used to analyze a suite of basaltic glasses from the Pacific–Antarctic ridge (PAR) and the Mid-Atlantic ridge (MAR). The magmatic differentiation involving concurrent sulfide segregation results in significant chalcophile element fractionation but no measurable Se isotopic variation. Because of the demonstrated lack of Se isotopic fractionation between sulfides and silicate melt, the Se isotope systematics of MORB reflects a source signature. The southern MAR displays a significant source heterogeneity due to the localized interaction between the ridge and Shona and Discovery mantle plumes that incorporate recycled components

Gradabschätzungen für den Kreisumfang von Graphen

In dieser Dissertation werden neue Gradabschätzungen für den Kreisumfang c(G) von k-zusammenhängenden Graphen G mit 3 = (k+1)delta-(k+1)(k-1) gilt, wenn L(G-C) >= k-1 und G ein (k+1)-zusammenhängende Graph ist. Die Ausnahmeklassen bzgl. dieser Abschätzungen für k-zusammenhängende Graphen werden im wesentlichen bestimmt. Für 3-zusammenhängende Graphen G werden die Ausnahmeklassen bzgl. der Abschätzung |C| >= 4delta-c bei L(G-C) >= 2 für 5 = k >= 5 and L(G-C) >= k-1. It is known that c(G)= |C| >= (k+1)delta-(k-1)(k+1), if G is (k+1)-connected and n = |G| >= (k+1)&delta;-k(k-1), if G is k-connected. The exceptional classes for these estimates when the connectivity is reduced by 1 are essentially determined. Moreover, for 3-connected graphs G, the exceptional classes for the estimates c(G) >= 4delta-c for 5 <= c <= 8 are essentially characterized

間隙充填モルタルの流動性及び材料分離抵抗性に関する研究

首都大学東京, 2018-03-25, 博士（工学）首都大学東