Agglomeration, Evaporation And Morphological Changes In Droplets With Nanosilica And Nanoalumina Suspensions In An Acoustic Field

Acoustic levitation permits the study of droplet dynamics without the effects of surface interactions present in other techniques such as pendant droplet methods. Despite the complexities of the interactions of the acoustic field with the suspended droplet, acoustic levitation provides distinct advantages of controlling morphology of droplets with nanosuspensions post precipitation. Droplet morphology is controlled by vaporization, deformation and agglomeration of nanoparticles, and therefore their respective timescales are important to control the final shape. The balance of forces acting on the droplet, such as the acoustic pressure and surface tension, determine the geometry of the levitated droplet. Thus, the morphology of the resultant structure can be controlled by manipulating the amplitude of the levitator and the fluid properties of the precursor nanosuspensions. The interface area in colloidal nanosuspensions is very large even at low particle concentrations. The effects of the presence of this interface have large influence in the properties of the solution even at low concentrations. This thesis focuses on the dynamics of particle agglomeration in acoustically levitated evaporating nanofluid droplets leading to shell structure formation. These experiments were performed by suspending 500µm droplets in a pressure node of a standing acoustic wave in a levitator and heating them using a carbon dioxide laser. These radiatively heated functional droplets exhibit three distinct stages, namely, pure evaporation, agglomeration and structure formation. The temporal history of the droplet surface temperature shows two inflection points. Morphology and final precipitation structures of levitated droplets are due to competing mechanisms of particle agglomeration, evaporation and shape deformation. This thesis provides iv a detailed analysis for each process and proposes two important timescales for evaporation and agglomeration that determine the final diameter of the structure formed. It is seen that both agglomeration and evaporation timescales are similar functions of acoustic amplitude (sound pressure level), droplet size, viscosity and density. However it is shown that while the agglomeration timescale decreases with initial particle concentration, the evaporation timescale shows the opposite trend. The final normalized diameter hence can be shown to be dependent solely on the ratio of agglomeration to evaporation timescales for all concentrations and acoustic amplitudes. The experiments were conducted with 10nm silica, 20nm silica, 20nm alumina and 50nm alumina solutions. The structures exhibit various aspect ratios (bowls, rings, spheroids) which depend on the ratio of the deformation timescale (tdef) and the agglomeration timescale (tg). For tde

Productive Development Policies in Costa Rica: Market Failures, Government Failures, and Policy Outcomes

This paper analyzes five Productive Development Policies (PDPs) implemented in Costa Rica, finding that they are not optimally addressing market failures. Moreover, government failures rather than market failures represent the main justification for PDPs. Even in the presence of market failures, the policy instruments applied are not necessarily the most economically efficient but rather the most politically feasible options. In addition, the lack of policy evaluation and monitoring prevents adjustments and corrections of such policies. Addressing the arguments for policy intervention and incorporating the results of evaluation into policy design and reform are necessary conditions for success. In spite of positive policy outcomes, limitations to enhance competitiveness and create the conditions for productivity growth are still present. An umbrella approach in the case of those PDPs that reinforce each other is necessary for productivity growth.Policy Analysis, Policy Making, Industrial Policy, Costa Rica

Climate change and agricultural structural change : the relevance for machinery use and acquisition in Germany

This thesis is a contribution to the research project Regional Climate Change, funded by the German Research Foundation (Deutsche Forschungsgemeinschaft, DFG Forschergruppe 1695 Regionaler Klimawandel). The projects objective was to learn about the vulnerability and sensitivity of typical land systems in Southwest Germany and identify suitable strategies for adaptation. The doctoral work contributes with empirical and methodological insights of farmers likely management adaptations in light of the farm managerial challenges arising from climate and structural change in Germany. The agricultural structure in Germany has strongly changed in the last 60 years. Where before numerous small-scale and labor-intensive farms were observed, it is now the place where fewer and highly mechanized farms contribute to agricultural production. The ongoing agricultural structural change in Germany is characterized by a trend in which many farms exit the agricultural sector, and the remaining --growth-oriented-- farmers take over the land, reorganize their farm business, and expand their operations. Nevertheless, this trend of farm growth, which is expected to continue in the future, poses significant challenges at the farm management level: Decisions on machinery use and acquisition play a crucial role in shaping the farm cost structure, and represent a critical element for maintaining competitiveness. Particularly for the expansion efforts, farm managers face a highly complex decision-making process to acquire the proper machinery capacities for field operations. Moreover, an additional factor will need to be considered for adequate decision-making: Climate change developments and the uncertainties associated with this process will likely increase the complexity of the farmers decision-making regarding the best reorganizational strategies towards farms expansion. Changes in the natural conditions for crop growth and development will likely result in management adaptations, e.g., changing the timing for fieldwork operations or changing land-use patterns. An analysis of the complex interactions and interdependencies between the environment and the farm system, on the one hand, and the resources and production possibilities available to the farm manager in the course of farm expansion on the other hand, require adequate tools of analysis. This work analyzes three dimensions of farm machinery management in the context of climate change and agricultural structural change. The first element of analysis corresponds to an examination of the sensibility of land-use and machinery investment decisions to climate change scenarios with the agent-based MPMAS model constructed for Central Swabian Jura in Southwest Germany. The Central Swabian Jura MPMAS model is a constitutive part of the bioeconomic modeling system MPMAS_XN. The MPMAS_XN system integrates the agricultural economic agent-based software MPMAS and the plant-soil modeling software Expert-N (XN) into a fully coupled system. The assessment of the sensibility and responsiveness of the MPMAS component revealed complex adaptation responses of land-use and machinery investment decisions as a result of shifted timing in fieldwork operations (e.g., harvesting or fertilization tasks). The second element of analysis corresponds to an examination of economies of size arising from farm machinery use and acquisition decisions in arable farms that follow a typical crop rotation practiced in Germany. For the analysis, a whole-farm multiperiod mathematical program implemented in the agent-based software MPMAS was employed. Optimizations were run and evaluated at a broad range of farm sizes and two distinctive distributions of availability of fieldwork days estimated for Southwest Germany. The results allowed observing patterns of optimal farm machinery demand and cost curves for several evaluated farm sizes and distributions of available fieldwork days distributions. The third main element of this work corresponds to a methodological contribution to the MPMAS_XN model system. Within this element, the implementation, functioning, and potential of an external theory-based MPMAS module are presented. The external module represents dynamics for joint machinery investments among simulated farm agents and serves as an enhancing methodological contribution for analyzing and representing farm machinery management in the agent-based software MPMAS.Diese Arbeit ist ein Beitrag zum von der Deutschen Forschungsgemeinschaft geförderten Projekt Regionaler Klimawandel, dessen Ziel es war die Verwundbarkeit und Sensitivität typischer Landsysteme in Südwestdeutschland zu untersuchen und geeignete Anpassungsstrategien zu identifizieren. Diese Doktorarbeit liefert empirische und methodische Erkenntnisse über die wahrscheinlichen Managementanpassungen der Landwirte und Landwirtinnen angesichts der Herausforderungen der Betriebsführung, die sich aus dem Klima- und Strukturwandel in Deutschland ergeben. Die Agrarstruktur in Deutschland hat sich in den letzten 60 Jahren stark verändert. Wo früher zahlreiche kleine und arbeitsintensive Betriebe beobachtet wurden, tragen heute weniger, dafür aber hochmechanisierte Betriebe zur landwirtschaftlichen Produktion bei. Dieser anhaltende landwirtschaftliche Strukturwandel in Deutschland kennzeichnet sich dadurch, dass viele Betriebe den Agrarsektor verlassen und die verbleibenden, wachstumsorientierten Landwirte und Landwirtinnen die Produktion übernehmen, ihre Betriebe neu organisieren und ihre Tätigkeiten ausweiten. Dieser Wachstumstrend, der sich voraussichtlich in Zukunft fortsetzen wird,hat erhebliche Herausforderungen auf der Ebene des Betriebsmanagements zur Folge: Entscheidungen über den Einsatz und die Anschaffung von Maschinen spielen eine entscheidende Rolle bei der Gestaltung der Betriebskostenstruktur und sind daher ein zentrales Element für die Aufrechterhaltung der Wettbewerbsfähigkeit. Insbesondere bei den Expansionsbemühungen stehen die BetriebsleiterInnen vor einem hochkomplexen Entscheidungsprozess, um die passenden Maschinenkapazitäten für den Feldeinsatz zu erwerben. Neben dem Erwerb und der optimalen Nutzung von Maschinen muss ein zusätzlicher Faktor für eine angemessene Entscheidungsfindung berücksichtigt werden: Die Entwicklung des Klimawandels und die mit diesem Prozess einhergehenden Unsicherheiten werden die Komplexität der Entscheidungsfindung hinsichtlich der besten Umstrukturierungsstrategien für die Expansion der landwirtschaftlichen Betriebe vermutlich weiter erhöhen. Dadurch entstehenden Änderungen der natürlichen Bedingungen für Pflanzenwachstum und -entwicklung wird wahrscheinlich mit Anpassungen des Managements begegnet, z.B. durch Verschiebung derFeldarbeitszeitpunkte oder durch Veränderung der Landnutzungsmuster. Eine Analyse der geschilderten komplexen Wechselwirkungen und Abhängigkeiten, einerseits zwischen Umwelt und landwirtschaftlichen Systemen, andererseits zwischen Ressourcen und Produktionsmöglichkeiten, die den Verantwortlichen zur Betriebserweiterung zur Verfügung stehen, erfordert geeignete Analysewerkzeuge. Diese Arbeit analysiert drei Dimensionen des Landmaschinenmanagements im Kontext des Klimawandels und des landwirtschaftlichen Strukturwandels. Im ersten Analyseelement wird die Sensibilität von Landnutzungs- und Maschineninvestitionsentscheidungen in Bezug auf verschiedene Klimawandelszenarien untersucht. Diese Analyse wird mit dem agentenbasierten MPMAS Modell durchgeführt, das für die mittlere Schwäbischen Alb in Südwestdeutschland erstellt wurde. Das MPMAS- Modell ist ein wesentlicher Bestandteil des bioökonomischen Modellierungssystems MPMAS_XN. Das MPMAS_XN Modellierungssystem integriert die agrarökonomische, agentenbasierte MPMAS Software und die Pflanzen-Boden-Modellierungssoftware Expert-N (XN) in ein vollständig gekoppeltes System. Die Bewertung der Sensibilität und Reaktionsfähigkeit der MPMAS Komponente zeigt komplexe Anpassungsreaktionen von Landnutzungs- und Maschineninvestitionsentscheidungen als Ergebnis eines verschobenen Zeitplans bei Feldarbeiten (z. B. Ernte- oder Düngungsaufgaben). Im zweiten Schritt befasst sich die vorliegende Arbeit mit einer Untersuchung der Skaleneffekte, die sich aus den Kaufentscheidungen und dem Einsatz von Landmaschinen in Ackerbetrieben ergeben, in denen eine für Deutschland übliche Fruchtfolge angebaut wird. Für die Analyse wird ein in der agentenbasierten Software MPMAS implementiertes mathematisches Mehrperiodenprogramm für den gesamten landwirtschaftlichen Betrieb verwendet. Optimierungen werden in einem breiten Spektrum von Betriebsgrößen und zwei unterschiedlichen Verteilungen der Verfügbarkeit von Feldarbeitstagen, die für Südwestdeutschland geschätzt werden, durchgeführt und bewertet. Die Ergebnisse ermöglichen die Beobachtung von Mustern der optimalen Nachfrage nach landwirtschaftlichen Maschinen sowie der Kostenkurven für die betrachteten Betriebsgrößen und Verteilungen der verfügbaren Feldarbeitstage. Der dritte Hauptteil dieser Arbeit stellt einen methodischen Beitrag zum MPMAS_XN Modellsystem dar. In diesem Element werden die Implementierung, Funktionsweise und das Potenzial eines externen und theoretisch aufgebauten MPMAS-Moduls vorgestellt. Dieses externe Modul repräsentiert die Dynamik, die sich aus gemeinsamen Maschineninvestitionen zwischen simulierten Computer-Agenten ergibt und dient als verbesserter methodischer Beitrag zur Analyse und Darstellung des Landmaschinenmanagements in der Agentenbasierte Software MPMAS

Modelo de vivienda social a partir del uso integral de la Guadua angustifolia Kunth para las zonas urbanas y rurales de Nicaragua

Según los estudios de déficit habitacional en América Latina del BID, En Nicaragua el 78 por ciento de las familias nicaragüenses no posee un hogar digno; según datos oficiales para el año 2017 el país enfrenta un déficit de Como respuesta ante esta realidad en el año 2009, en Nicaragua se formó la “Ley Especial para el Fomento de la construcción de Vivienda y de Acceso a la Vivienda de Interés Social”3. La cual fomenta continuamente la organización y ejecución de proyectos de construcción de viviendas sociales en todo el país. Nicaragua enfrenta a la actualidad un déficit habitacional de aproximadamente un millón de viviendas, por lo que año tras año, el gobierno dirige grandes fondos de inversión para de reducir este marcado déficit habitacional, agravado por los altos costos de materiales de construcción, transporte, y los severos daños ocasionados al medio ambiente por la fabricación de mucho de estos materiales

Identifying Web Tables - Supporting a Neglected Type of Content on the Web

The abundance of the data in the Internet facilitates the improvement of extraction and processing tools. The trend in the open data publishing encourages the adoption of structured formats like CSV and RDF. However, there is still a plethora of unstructured data on the Web which we assume contain semantics. For this reason, we propose an approach to derive semantics from web tables which are still the most popular publishing tool on the Web. The paper also discusses methods and services of unstructured data extraction and processing as well as machine learning techniques to enhance such a workflow. The eventual result is a framework to process, publish and visualize linked open data. The software enables tables extraction from various open data sources in the HTML format and an automatic export to the RDF format making the data linked. The paper also gives the evaluation of machine learning techniques in conjunction with string similarity functions to be applied in a tables recognition task.Comment: 9 pages, 4 figure

Insight into morphology changes of nanoparticle laden droplets in acoustic field

Hollow structures with unique morphologies form due to particle agglomeration in acoustically levitated nanofluid functional droplets when subjected to external heating. The final diameter of the structure depends only on the ratio of agglomeration to evaporation time scales for various nanoparticle laden droplets, and not on the type of the suspended particles. These time scales depend only on nanoparticle concentration. This valuable information may be exploited to form microstructures with desired properties from ceramic compounds. Phase diagrams for alumina and silica droplets indicate the transition from a bowl to ring structure depending on concentration

Patient\u27s Perception of the IV Experience in the Emergency Department

The pain associated with IV insertion can create a stressful experience for ED patients. The objective of this comparative study is to determine whether the use of a topical vapocoolant spray (Pain Ease) prior to IV insertion would be an effective means of reducing pain and anxiety in adult ED patients. Stable ED patients requiring an IV were included in the study, with some exclusions. 100 consented patients were randomly chosen to participate; Pain Ease vapocoolant spray was used on half of those prior to IV insertion. Data collection was done by ED nurses. The same study questionnaire was used with 2 groups of consented patients, those with and without Pain-Ease applied just prior to IV insertion. The RN documented their perception of vein quality and the ease of IV insertion. The patient rated the levels of pain and anxiety with IV insertion. Patients who had Pain Ease used were asked if they would want the spray to be used for future IV’s. ED RNs perceived minimal difficulty with IV insertions. There was no statistical difference in the comparison of patient pain or anxiety for IV starts with or without the use of Pain Ease prior to the IV insertion. Of patients who did have a vapocoolant used prior to ED insertion, 74% would like to have it used again. Both the RN perceptions of difficulty and the patient perceptions of pain/anxiety scored very low, with and without the use of a vapocoolant. There is some benefit to the use of a vapocoolant, because 74% of the patients who did have it would request it again. While the use of a vapocoolant with all ED patients was not supported, it remains an available adjunct when needed to allay anxiety and discomfort

El control del empleador con respecto a la dignidad e intimidad del trabajador

Trabajo de final de graduación de 133 páginas en formato pdfCon qué límites se puede controlar la prestación del servicio y como ejecutar ese control. Si bien es cierto que la tecnología permite el desarrollo eficiente de las labores, estas nuevas tecnologías potenciales, las facultades de control y vigilancia por parte del empleador deben ser justificables y que no violen el derecho de la intimidad del trabajador. Además existen nuevas formulas de trabajo que generalmente son menos evidentes, la limitación entre el ámbito profesional y el ámbito personal de los trabajadores. La vigilancia del empresario en las actividades de sus trabajadores, pueden afectar la intimidad de los trabajadores. En especial pretender exigir que ninguna actividad de la esfera personal se realice en el trabajo. Es importante mencionar que en la doctrina ya se habla del derecho del trabajador a un grado razonable de libertad a la hora de determinar sus actuaciones en el trabajo, sin ser constantemente vigilados. Obviamente el trabajador tiene derecho a que se otorgue cierta tutela de la vida privada, en el lugar del trabajo. Otro es el que se tenga derecho libre e irrestricto de la vida privada dentro del trabajo.Universidad Estatal a Distancia de Costa Ric

Difficulties to identify and pronounce the sounds /s/ and /z/ as EFL students in the second semester 2013, belonging to the Saturday program of the English Major at UNAN MANAGUA

One major concern about the EFL Saturday courses at UNAN-Managua is if the students are acquiring a good level of proficiency on pronunciation. It is a strong belief that EFL learners have great difficulties on pronunciation due to negative transfer; especially with difficult twin sounds which do not have an equivalent in the mother tongue of non-native speakers. This research was applied to a group of 15 students of the Saturday program of the English Major at UNAN. To this purpose were applied one survey to the students, two interviews, and several class observations. There were interesting findings about the subject and the most important is the concern to create phonological awareness in the students to improve their pronunciation