Search results for "Spark"
showing 10 items of 124 documents
Implementation of early childhood physical curriculum (SPARK) in the Central Valley of California (USA)
2017
Abstract The aim of this paper is to describe the methodology applied to develop and launch the implementation of physical activity curriculum (SPARK) at several schools in the Central Valley of California. The SPARK Early Childhood Program is one of eight within the SPARK Coordinated School Health (CSH) model. This research try to create environments that promote healthful behaviors at school and in the community for both children and adults. Overweight and obese children are likely to develop serious health problems. Among children in the U.S., Latino children are affected disproportionally by the obesity epidemic. Ninos Sanos, Familia Sana (Healthy Children, Healthy Family) is a five-yea…
Essays On European Natural Gas Market
2018
La presente tesis ha cubierto diferentes aspectos de los mercados europeos del gas natural y la electricidad, en particular algunas propiedades que afectan a la efectividad de la cobertura, como la estacionalidad en varianza y en precios. Asimismo, se ha realizado un estudio de la prima de riesgo del gas natural, su relación con las variables de riesgo y su descomposición en una prima de riesgo de reinversión o ‘rollover’ y una prima de ‘preferencia por liquidez’ relacionada con el plazo. La tesis se compone de tres capítulos: el Capítulo I estudia la estacionalidad en los precios y la volatilidad y cómo mejora la efectividad de la cobertura teniendo en cuenta dicha estacionalidad; el Capít…
Use of organic fertilizers for lettuce plug plant production
2009
Vegetable crop production in conventional intensive agricultural systems commonly implies high fertilization rates. Recent data show that the worldwide demand for organically grown products is expanding rapidly. Increasing interest in organic vegetable production has lead to a need to produce seedlings organically. The aim of this study was to evaluate the effects of different levels of organic fertilizers applied to lettuce seedlings on plant growth and yield. Romaine lettuce seeds of cultivar Gretta R were sown on March 2007 in polystyrene plug trays in a unheated greenhouse in the Northern coast of Sicily. At the second leaf stage, seedlings were saturated with solutions containing vario…
The determinants affecting the internationalisation of the Italian SMEs producing sparkling wines: An empirical study on the RBV of the firms
2014
In the last few years, wine industry has been characterised by profound changes that have determined an intensification of competition on a global scale. The aim of this study is to identify the firms’ internal factors that most influence the export intensity and the ability to fit into the international market of the Italian wineries producing sparkling wines through a resource-based view (RBV) approach. Results of our study supporting the findings of previous empirical researches presented in this paper. In particular, the main factors affecting export intensity are: innovation degree and intensity of investment in advertising and promotion, among firms’ characteristics, and abroad experi…
A mathematical model for the prediction of the injected mass diagram of a S.I. engine gas injector
2013
A mathematical model of gaseous fuel solenoid injector for spark ignition engine has been realized and validated through experimental data. The gas injector was studied with particular reference to the complex needle motion during the opening and closing phases, which strongly affects the amount of fuel injected. As is known, in fact, when the injector nozzle is widely open, the mass flow depends only on the fluid pressure and temperature upstream the injector: this allows one to control the injected fuel mass acting on the “injection time” (the period during which the injector solenoid is energized). This makes the correlation between the injected fuel mass and the injection time linear, e…
High-speed solid state fluorination of Nb2O5 yields NbO2F and Nb3O7F with photocatalytic activity for oxygen evolution from water
2021
Solid state reactions are slow because the diffusion of atoms or ions through the reactant, intermediate and crystalline product phases is the rate-limiting step. This requires days or even weeks of high temperature treatment, and consumption of large amounts of energy. We employed spark-plasma sintering, an engineering technique that is used for high-speed consolidation of powders with a pulsed electric current passing through the sample to carry out the fluorination of niobium oxide in minute intervals. The approach saves time and large amounts of waste energy. Moreover, it allows the preparation of fluorinated niobium oxides on a gram scale using poly(tetrafluoroethylene) (®Teflon) scrap…
Rapid continous radiochemical separations by thermochromatography in connection with a gas-jet recoil-transport system
1980
Abstract A combination of a gas-jet recoil-transport system with a thermochromatographic system has been studied as a technique for rapid, continuous radiochemical separations. Fission products were used as a model for complex mixtures of elements. A nitrogen gas-jet containing potassium chloride clusters was applied to transport nuclides produced in a reactor from the target area to the thermochromatographic column. Conversion of the reaction products carried by the gas-jet volatile species was achieved by stopping the clusters in a quartz-wool plug located in the column and kept at high temperatures and feeding a reactive gas into the column. Several reactive gases producing volatile chlo…
NOX reduction and efficiency improvements by means of the Double Fuel HCCI combustion of natural gas–gasoline mixtures
2016
Abstract Homogeneous Charge Compression Ignition (HCCI) and Double Fuel (DF) combustion represent two innovative processes sharing a strong potential for pollutant emissions and fuel consumption reduction. HCCI regards the auto-ignition of a homogeneous premixed charge of air and fuel, featuring very low NOX emissions and good efficiency. Double Fuel (DF) instead indicates the simultaneous combustion of gasoline and natural gas (or gasoline and LPG), premixed with air by the port injection of both fuels within same engine cycle. Since fuel mixtures enhances the HCCI performances widening the range of possible operating conditions, the authors tested the HCCI combustion process using natural…
The Experimental Validation of a New Thermodynamic Method for TDC Determination
2007
In-cylinder pressure analysis is becoming more and more important both for research and development purpose and for control and diagnosis of internal combustion engines; directly measured by means of a combustion chamber pressure transducers or evaluated by analysing instantaneous engine speed [1,2,3,4], incylinder pressure allows the evaluation of indicated mean effective pressure (IMEP), combustion heat release, combustion phase, friction pressure, etc...It is well known to internal combustion engine researchers that for a right evaluation of these quantities the exact determination of Top Dead Centre (TDC) is of vital importance: a 1° error on TDC determination can lead to evaluation err…
Spark plasma sintering of cobalt ferrite nanopowders prepared by coprecipitation and hydrothermal synthesis.
2007
International audience; Cobalt ferrite exhibits a high coercivity at room temperature and a strong magnetic anisotropy compared to the other spinel ferrites and, consequently appears as an interesting material for permanent magnets and high-density recording. The magnetic properties depend also on the crystallite size. In order to keep the powder properties in a bulk material, dense nanostructured cobalt ferrite has to be sintered. A field activated sintering process like spark plasma sintering (SPS) may be promising for such challenge. The present paper deals with: (i) the preparation of cobalt ferrite by two methods: coprecipitation and hydrothermal synthesis in supercritical water; (ii) …