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91.
S. Di Carlo M. Falasconi E. SanchezA. Scionti G. SquilleroA. Tonda 《Pattern recognition letters》2011,32(13):1594-1603
Artificial olfaction systems, which mimic human olfaction by using arrays of gas chemical sensors combined with pattern recognition methods, represent a potentially low-cost tool in many areas of industry such as perfumery, food and drink production, clinical diagnosis, health and safety, environmental monitoring and process control. However, successful applications of these systems are still largely limited to specialized laboratories. Sensor drift, i.e., the lack of a sensor’s stability over time, still limits real industrial setups. This paper presents and discusses an evolutionary based adaptive drift-correction method designed to work with state-of-the-art classification systems. The proposed approach exploits a cutting-edge evolutionary strategy to iteratively tweak the coefficients of a linear transformation which can transparently correct raw sensors’ measures thus mitigating the negative effects of the drift. The method learns the optimal correction strategy without the use of models or other hypotheses on the behavior of the physical chemical sensors. 相似文献
92.
Alkali-free glass as a high energy density dielectric material 总被引:3,自引:0,他引:3
One of the greatest challenges in the development of new high energy density materials is to increase dielectric permittivity while maintaining high breakdown strength. The dielectric breakdown behavior of an alkali-free barium boroaluminosilicate glass is shown to have remarkably high DC dielectric breakdown strength (12 MV/cm) and reasonably high permittivity (~ 6), equating to energy densities in excess of 35 J/cm3. This behavior is attributed to highly polarizable Ba ions enhancing the real part of complex permittivity, the low loss due to the alkali-free composition, and the substantially defect-free quality of the glass and its surfaces. To our knowledge, this is the highest breakdown strength reported for a bulk glass, and rivals the breakdown strength more typically observed in pristine thin films of SiO2. These findings indicate that alkali-free multicomponent glasses may be strong candidates for next-generation high energy density storage capacitors for portable or pulsed power applications. 相似文献
93.
Carlo Paolo Sasso Peiqi Zheng Vittorio Basso Peter Müllner David C. Dunand 《Intermetallics》2011,19(7):952-956
The high surface/volume ratio and mechanical stability under cyclic strain makes polycrystalline Ni–Mn–Ga metallic foams attractive for magnetic refrigeration. By means of comparison with a polycrystalline bulk material, we have demonstrated that the porous structure of Ni54.8Mn20.2Ga25.0 open-cells metallic foams (porosity varying between 44% and 58%) reduces the temperature span of the phase transition and increases the magnetocaloric effect (MCE). MCE was investigated using calorimetry in a magnetic field. Temperature scan and isothermal experiments have shown a 0.8 K T?1 shift of the phase transition temperature and a maximum irreversible entropy change of 2.5 Jkg?1 K?1. The results indicate that metallic foams can represent a good approach for enhancing field induced phase transitions in magnetic refrigeration applications. 相似文献
94.
Edoardo Artioli Lourenco Beirão da Veiga Harri Hakula Carlo Lovadina 《Computational Mechanics》2009,44(1):45-60
We consider the free vibration problem of thin shells of revolution of constant type of geometry, focusing on the asymptotic
behaviour of the lowest eigenfrequency, as the thickness tends to zero. Numerical experiments are computed using two discretization
methods, collocation and finite elements, each corresponding to a different shell model. Our results are in agreement with
theoretical results obtained using interpolation theory and cited in literature. 相似文献
95.
96.
The study investigates the effects of the roughness of the metal counterface (mirror finished or polished) on the coefficient of dry friction for some of the most common engineering plastics used in current bearing technology. The results show that an optimal roughness for minimum friction is likely to exist for any polymer, and it depends on the bulk properties of the polymer itself. “Soft” plastics characterized by a low modulus of elasticity exhibit better sliding behaviour on very smooth, mirror finished surfaces, whereas for high-modulus plastics lower friction is measured in combination with rougher, polished counterfaces. The influence of the contact pressure and sliding velocity are also investigated and found to depend on the layout of the tribological system. 相似文献
97.
Homam Naffakh Moosavy Mohammad-Reza Aboutalebi Seyed Hossein Seyedein Carlo Mapelli 《Journal of Materials Processing Technology》2013,213(11):1875-1884
The Scheil equation was used to model the solidification path, microsegregation of alloying elements in the interdendritic regions, solidification temperature ranges, and to predict the formation of secondary structures and the castability behavior of as-cast superalloys. 4 experimental alloys with pre-specified γ-Ti,Nb,Al,Mo composition containing different Nb, Ti and Al contents were designed using vacuum induction melting furnace. The produced as-cast superalloys were characterized using optical and scanning electron microscopy equipped with energy dispersive X-ray spectrometer and TG–DSC analysis. The experiments showed logic conformity to the modeling results. The model and experiment confirmed the highest segregation behavior for Ti and Nb. All the experimental superalloys indicated the remarkable tendency to form secondary eutectic structures at the last stages of solidification. Superalloy with chemical composition of γ-3.5%Mo,1.8%Al,4%Ti,2.9%Nb showed the shorter solidification temperature range and the best castability. 相似文献
98.
Ian Laboriante Maxwell Fisch Amir Payamipour Fang Liu Carlo Carraro Roya Maboudian 《Tribology Letters》2011,44(1):13-17
The evolution of morphology, electrical properties, and chemical composition has been studied in cyclically contacting polycrystalline
silicon (polysilicon) surfaces coated with perfluoroalkylsilane self-assembled monolayer (SAM). The microinstrument used is
a MEMS cantilever that is repeatedly actuated out-of-plane to impact a landing pad and is then moved in-plane to enable nondestructive
in situ inspection of the impacted area. Analyses show that a device with a monolayer coating exhibits signs of surface degradation
after a much higher number of cycles than its uncoated counterpart. A sharp increase in contact resistance between the cantilever
and landing pad is observed at ~10 billion cycles for a coated device, versus ~25 million cycles for an uncoated device. Likewise,
the onset of grain fracture in the landing pad occurs at ~25 billion cycles for the SAM-coated device, versus ~3 billion cycles
for its uncoated counterpart. The effectiveness of the monolayer coating diminishes after more than 100 billion contact cycles
as the SAM layer is removed, and the polysilicon substrate becomes susceptible to adhesive wear. 相似文献
99.
Gerardo M. Verderame Paolo Ricci Giovanni De Carlo Gaetano Manfredi 《Construction and Building Materials》2009,23(12):3499-3511
In recent years there has been wide use of non-linear dynamic analysis for the evaluation of existing structures in areas of high seismic risk. In the simulation of the cyclic behaviour of elements in reinforced concrete (RC) its bonding performance cannot be ignored. There are numerous numerical models developed in recent decades which can explicitly account for the slip between reinforcing bars and the surrounding concrete through the definition of the local hysteretic bond–slip relationship. As for plain bars, commonly used in reinforced concrete buildings before the 1970s, there are almost no references to hysteretic bond mechanisms.This paper describes the results of a series of monotonic and cyclic pull-out tests aimed at the assessment of the bond performances of plain round bars. Monotonic behaviour is characterized by a first ascending branch, up to the maximum bond strength; in this phase, as the slip increases, chemical–physical adhesion and micro-interlocking between the cement paste and the indentations of the bar surface progressively activate. During post-peak phase the only frictional contribute is present, gradually degrading towards a minimum value as the slip increases. The two parameters, maximum bond strength and minimum frictional bond, in spite of the high variability shown, seem to reflect well the literature indications about bond performances of plain bars. In cyclic field, where the only frictional mechanism is present, experimental results show a significant degradation of bond capacities. Hysteretic cycles show a singular shape, characterized by a reloading phase showing a slight reduction for slip values approaching zero and a subsequent increase in bond stress towards the maximum imposed slip. Bond stresses in cyclic field show a high variability, but it is generally possible to recognize a decreasing trend both with the number of cycles and with the maximum imposed slip. 相似文献
100.
The 12-month pre-Ph.D. ICTP Diploma Courses in the fields of Condensed Matter Physics, High Energy Physics, Mathematics, Earth System Physics and Basics Physics have been recorded using the automated, low cost recording system called EyA developed in-house. We discuss the technical details on how these recordings were implemented, together with some web usage statistics and students feedback. As yet, no similar endeavor has been made to put on-line a complete high-level Diploma Programme, due to the high costs involved when using alternative recording solutions. These recordings are freely available on the website www.ictp.tv. 相似文献