El Museo Etnográfico de La Rioja

En número dedicado a: Provincia de Logroñ

A Pseudo-Measure of Fuzziness

In this note we give an example of a gradationof openness (a fuzzy topology in Shostak’s sense) and deduce from it a pseudo-measure of fuzziness

Years of sunlight exposure and cataract: a case-control study in a Mediterranean population.

BACKGROUND: We aimed to investigate the relation between sunlight exposure and risk of cataract. METHODS: We carried out a frequency-matched case-control study of 343 cases and 334 controls attending an ophthalmology outpatient clinic at a primary health-care center in a small town near Valencia, Spain. All cases were diagnosed as having a cataract in at least one eye based on the Lens Opacification Classification system (LOCS II). Controls had no opacities in either eye. All cases and controls were interviewed for information on outdoor exposure, "usual" diet, history of severe episodes of diarrhea illness, life-style factors and medical and socio-demographic variables. Blood antioxidant vitamin levels were also analyzed. We used logistic regression models to estimate sex and age-adjusted odds ratios (ORs) by quintiles of years of occupational outdoor exposure, adjusting for potential confounders such as smoking, alcohol consumption, serum antioxidants and education. RESULTS: No association was found between years of outdoor exposure and risk of cataract. However, exploratory analyses suggested a positive association between years of outdoor exposure at younger ages and risk of nuclear cataract later in life. CONCLUSION: Our study does not support an association with cataract and sunlight exposure over adult life

A RCCI operational limits assessment in a medium duty compression ignition engine using an adapted compression ratio

Reactivity Controlled Compression Ignition concept offers an ultra-low nitrogen oxide and soot emissions with a high thermal efficiency. This work investigates the capabilities of this low temperature combustion concept to work on the whole map of a medium duty engine proposing strategies to solve its main challenges. In this sense, an extension to high loads of the concept without exceeding mechanical stress as well as a mitigation of carbon oxide and unburned hydrocarbons emissions at low load together with a fuel consumption penalty have been identified as main Reactivity Controlled Compression Ignition drawbacks. For this purpose, a single cylinder engine derived from commercial four cylinders medium-duty engine with an adapted compression ratio of 12.75 is used. Commercial 95 octane gasoline was used as a low reactivity fuel and commercial diesel as a high reactivity fuel. Thus, the study consists of two different parts. Firstly, the work is focused on the development and evaluation of an engine map trying to achieve the maximum possible load without exceeding a pressure rise rate of 15 bar/CAD. The second part holds on improving fuel consumption and carbon oxide and unburned hydrocarbons emissions at low load. Results suggest that it is possible to achieve up to 80% of nominal conventional diesel combustion engine load without overpassing the constraints of pressure rise rate (below 15 bar/CAD) and maximum pressure peak (below 190 bar) while obtaining ultra-low levels of nitrogen oxide and soot emissions. Regarding low load challenges, it has developed a particular methodology sweeping the gasoline-diesel blend together with intake temperature or exhaust gas recirculation maintaining constant the combustion phasing and ultra-low nitrogen oxide and soot emissions. As a result a drastic decrease carbon oxide and unburned hydrocarbons emissions is obtained with a slight fuel consumption improvement.The authors would like to thank VOLVO Group Trucks Technology for supporting this research.Benajes Calvo, JV.; Pastor Soriano, JV.; García Martínez, A.; Boronat-Colomer, V. (2016). A RCCI operational limits assessment in a medium duty compression ignition engine using an adapted compression ratio. Energy Conversion and Management. 126:497-508. doi:10.1016/j.enconman.2016.08.023S49750812

Measurements of OH* and CH* Chemiluminescence in Premixed Flames in a Constant Volume Combustion Bomb under Autoignition Conditions

The objectives of this paper are as follows: (1) To study parametrically OH* and CH* chemiluminescence trace evolution as a function of the initial pressure, temperature, and equivalence ratio of premixed flames of n-heptane, under autoignition conditions, in a constant volume combustion bomb. The signals of the electronically excited states of OH* (306 nm) and CH* (430 nm) have been detected through band-pass filters with two photomultiplier tubes placed in an optical access of the combustion bomb. (2) To determine the feasibility of using OH* and CH* chemiluminescence signals as active-control parameters for premixed flames. For this purpose, a correlation between OH* chemiluminescence emissions and the equivalence ratio and the rate of heat release during the combustion process is obtained, as well as a correlation between CH* chemiluminescence emissions and the adiabatic flame temperature. (3) To investigate the relationship between the OH* and CH* chemiluminescent emissions in premixed combustions of n-heptane, iso-octane, and a mixture of 50% n-heptane and 50% toluene and the equivalence fuel/air ratio for a given initial temperature and pressure. To reach these objectives, measurements of OH* and CH* chemiluminescences from premixed flames of n-heptane with autoignition are reported at equivalence ratios ranging from 0.8 to 1.0, in a constant volume combustion bomb. The morphology of the curves and the relationships with parameters of interest during the combustion process (i.e., the rate of heat release, burned temperature, etc.) are studied. In addition, premixed combustions of iso-octane, n-heptane, and a mixture of n-heptane and toluene are also investigated at different fuel/air equivalence ratios for a given initial pressure and temperature, to assess the possibility of using the ratio between the OH* and CH* chemiluminescence signals to monitorize the equivalence ratio during the combustion, as other authors have considered previously. © 2010 American Chemical Society.The authors of this paper thank the Spanish Ministry of Science and Technology for the financial support of this research through the project TRA2007-67961-C03/AUT and the Regional Government of Castile and Leon through the funding for the GR203 Excellence Research Group. The authors also appreciate the help provided by Dr. Carot for the statistical design of experiments.Tinaut Fluixa, FV.; Reyes, M.; Giménez, B.; Pastor Soriano, JV. (2011). Measurements of OH* and CH* Chemiluminescence in Premixed Flames in a Constant Volume Combustion Bomb under Autoignition Conditions. ENERGY & FUELS. 25:119-129. https://doi.org/10.1021/ef1013456S1191292