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Search Results: 1 - 7 of 7 matches for " Gravalos "
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Fault Detection of Fuel Injectors Based on One-Class Classifiers  [PDF]
Dimitrios Moshou, Athanasios Natsis, Dimitrios Kateris, Xanthoula-Eirini Pantazi, Ioannis Kalimanis, Ioannis Gravalos
Modern Mechanical Engineering (MME) , 2014, DOI: 10.4236/mme.2014.41003

Fuel injectors are considered as an important component of combustion engines. Operational weakness can possibly lead to the complete machine malfunction, decreasing reliability and leading to loss of production. To overcome these circumstances, various condition monitoring techniques can be applied. The application of acoustic signals is common in the field of fault diagnosis of rotating machinery. Advanced signal processing is utilized for the construction of features that are specialized in detecting fuel injector faults. A performance comparison between novelty detection algorithms in the form of one-class classifiers is presented. The one-class classifiers that were tested included One-Class Support Vector Machine (OCSVM) and One-Class Self Organizing Map (OCSOM). The acoustic signals of fuel injectors in different operational conditions were processed for feature extraction. Features from all the signals were used as input to the one-class classifiers. The one-class classifiers were trained only with healthy fuel injector conditions and compared with new experimental data which belonged to different operational conditions that were not included in the training set so as to contribute to generalization. The results present the effectiveness of one-class classifiers for detecting faults in fuel injectors.

An Experimental Determination of Gross Calorific Value of Different Agroforestry Species and Bio-Based Industry Residues  [PDF]
Ioannis Gravalos, Panagiotis Xyradakis, Dimitrios Kateris, Theodoros Gialamas, Dimitrios Bartzialis, Kyriakos Giannoulis
Natural Resources (NR) , 2016, DOI: 10.4236/nr.2016.71006
Abstract: Solid biomass fuels are useful and cost effective renewable energy source. The energy content of biomass is determined by its calorific value. The objective of this study was to determine experimentally the gross calorific value (GCV) of different agroforestry species and bio-based industry residues that could be used by: a) companies specialized in processing raw biomass solid biofuel production, b) small-scale consumers (households, medium-sized residential buildings, etc.). The fuel samples used were from agricultural residues and wastes (rice husks, apricot kernels, olive pits, sunflower husks, cotton stems, etc.), energy crops and wetland herbs (cardoon, switchgrass, common reed, narrow-leaf cattail), and forest residues (populus, fagus, pinus). The GCV of the bio-mass samples was experimentally determined based on CEN/TS 14918:2005, and an oxygen bomb calorimeter was used (Model C5000 Adiabatic Calorimeter, IKA?-Werke, Staufen, Germany). The GCV of different agroforestry species and residues ranges from 14.3 - 25.4 MJ?kg1. The highest GCV was obtained by seeds and kernels due to higher unit mass and higher lipid content. Pinus sylvestris with moisture content 24.59% obtained the lowest GCV (13.973 MJ?kg1).
Synthesis and Electrophilic Substitution of Pyrido[2,3,4-kl]-acridines
Avi Koller,Amira Rudi,Marta Garcia Gravalos,Yoel Kashman
Molecules , 2001, DOI: 10.3390/60400300
Abstract: Several new pyrido[2,3,4-kl]acridines were synthesized by reacting naphthoquinone, juglone or cyclohexan-1,3-dione with β,β’-diaminoketones in a biomimetic reaction. The structure of all new compounds was elucidated by NMR and MS spectroscopy. Electrophilic substitution, mainly nitration, of the various compounds was undertaken and the substitution positions determined. A series of derivatives was prepared and their cytotoxicity towards P-388 mouse lymphoma cells analysed. The most cytotoxic derivatives were found to have IC50’s of 0.05 and 0.1 ug/ml.
Efeito da usinagem na estrutura e propriedades mecanicas do a?o superaustenítico ASTM A351 CN3MN
Gravalos, Márcio Tadeu;Martins, Marcelo;Diniz, Anselmo Eduardo;Mei, Paulo Roberto;
Rem: Revista Escola de Minas , 2007, DOI: 10.1590/S0370-44672007000100013
Abstract: super austenitic stainless steels are denominated as such because they present good resistance to pitting corrosion and, also, offer excellent mechanical properties, which makes them one of the options for the production of components used by the petroleum industry. however, the superficial foundry hardening during the machining processes can change these properties. this paper aimed at investigating the effects of the machining operation on the surface of the super austenitic steel astm a351 cn3mn. samples of the casted steel suffered wear due to cylindrical machining, with different cutting speeds, using indexable carbide inserts of varied geometries. the analysis of the microstructure on the casting surface was accomplished by optical microscopy and the foundry hardened surface was determined by micro-hardness. the mechanical properties of the steel were determined by traction assay. the wear in the cutting inserts was accomplished in a mev.
Influência da rugosidade na resistência à corros?o por pite em pe?as torneadas de a?o inoxidável superaustenítico
Gravalos, Márcio Tadeu;Martins, Marcelo;Diniz, Anselmo Eduardo;Mei, Paulo Roberto;
Rem: Revista Escola de Minas , 2010, DOI: 10.1590/S0370-44672010000100013
Abstract: pitting corrosion resistance has been correlated to the morphological conditions of the surface: a smooth surface finishing decreases the potential for pitting. this study aimed at investigating the relationship between pitting corrosion resistance and surface roughness in the machined surfaces of superaustenitic stainless steel astm a744 grade cn3mn. the samples of the casting steel were cylindrically turned sunder different combinations of cutting conditions, producing different surface roughness patterns. the surfaces of the samples, as machined, were characterized by roughness and hardness. after the application of an accelerated immersion corrosion test, these surfaces were examined in a stereoscope and the weight loss by corrosion was also determined. it was revealed that the samples exhibited different corrosion resistance behaviors, according to the machining conditions applied. a correlation between pitting resistance corrosion and machined surface roughness was evident, and also, the weight loss due to the formation of pits. this study has identified that corrosion can be controlled through the selection of appropriate machining parameters.
Boletín de la Sociedad Chilena de Química , 2001, DOI: 10.4067/S0366-16442001000100007
Abstract: several new 2,3-functionally dialkyl-1,4-benzohydroquinone diacetates have been prepared by oxidative cleavage of epoxide compounds iii, obtained from the diels-alder condensation product between the monoterpene myrcene and 1,4-benzoquinone. the nature of the isolated products is depending of the functionality of the side chain
Approach to early-onset colorectal cancer: Clinicopathological, familial, molecular and immunohistochemical characteristics
Jose Perea, Edurne Alvaro, Yolanda Rodríguez, Cristina Gravalos, Eva Sánchez-Tomé, Barbara Rivera, Francisco Colina, Pablo Carbonell, Rogelio González-Sarmiento, Manuel Hidalgo, Miguel Urioste
World Journal of Gastroenterology , 2010,
Abstract: AIM: To characterize clinicopathological and familial features of early-onset colorectal cancer (CRC) and compare features of tumors with and without microsatellite instability (MSI).METHODS: Forty-five patients with CRC aged 45 or younger were included in the study. Clinical information, a three-generation family history, and tumor samples were obtained. MSI status was analyzed and mismatch repair genes were examined in the MSI families. Tumors were included in a tissue microarray and an immunohistochemical study was carried out with a panel of selected antibodies.RESULTS: Early onset CRC is characterized by advanced stage at diagnosis, right colon location, low-grade of differentiation, mucin production, and presence of polyps. Hereditary forms represent at least 21% of cases. Eighty-one percent of patients who died during follow-up showed a lack of expression of cyclin E, which could be a marker of poor prognosis. β-catenin expression was normal in a high percentage of tumors.CONCLUSION: Early-onset CRC has an important familial component, with a high proportion of tumors showing microsatellite stable. Cyclin E might be a poor prognosis factor.
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