Characterization of MEMS accelerometer self-noise by means of PSD and Allan Variance analysis
In this paper, we have studied the sources of error of a low-cost 3-axis MEMS accelerometer by means of Power Spectral Density and Allan Variance techniques. These techniques were applied to the signals acquired from ten identical devices to characterize the variability of the sensor produced by the same manufacturer. Our analysis showed as identically produced accelerometer have somehow variable behavior in particular at low frequency. It is therefore of paramount importance before their use in Inertial Navigation or Earthquakes Monitoring System, a complete characterization of each single sensors.
SOLUZIONE IN FORMA CHIUSA PER IL CALCOLO DELLE FREQUENZE NATURALI DI CILINDRI A PARETE SOTTILE E BORDI INCASTRATI
In questo lavoro si presenta un modello matematico che consente di calcolare in forma chiusa ed in maniera accurata le frequenze naturali dei gusci cilindrici circolari isotropi a parete sottile e bordi incastrati. L’equazione delle frequenze è stata determinata applicando il principio di Hamilton, mediante il metodo di Rayleigh, al sistema di equazioni indefinite del moto derivanti dalla versione di Reissner della teoria di Love, opportunamente modificata con le assunzioni di Donnell. La validazione del modello è stata effettuata mettendone a confronto i risultati sia con quelli derivanti dall’analisi modale realizzata agli elementi finiti, sia con dati sperimentali e teorici presenti in l…
An experimental investigation on the long-term compatibility of preheated crude palm oil in a large compression ignition diesel engine
An experimental study was carried out on a large stationary compression ignition engine to evaluate the long-term compatibility and durability issues associated with the use of crude palm oil as fuel. Two different preheating temperatures (60 and 80 °C) were adopted to assess the potential improvements related to lower fuel viscosity. The results obtained, in terms of in-cylinder carbon deposits and engine wear, were compared with the results obtained using ordinary diesel fuel. For each fuel and preheating temperature, the engine was operated for 300 consecutive h, during which several engine lubricant samples were collected and analysed to determine soot and fuel contaminations, viscosity…
A closed-form solution for natural frequencies of thin-walled cylinders with clamped edges
Abstract This paper presents an approximate closed-form solution for the free-vibration problem of thin-walled clamped–clamped cylinders. The used indefinite equations of motion are classic. They derive from Reissner׳s version of Love׳s theory, properly modified with Donnell׳s assumptions, but an innovative approach has been used to find the equations of natural frequencies, based on a solving technique similar to Rayleigh׳s method, on the Hamilton׳s principle and on a proper constructions of the eigenfuctions. Thanks to the used approach, given the geometric and mechanical characteristics of the cylinder, the model provides the natural frequencies via a sequence of explicit algebraic equat…
A Low Cost Customizable Micro-ROV for Environmental Research - Applications, Advances and Challenges
Summary Several shallow submarines areas are characterized by considerable releases of hydrocarbon gases, which, during earthquakes or volcanic activity, may suddenly and violently occur. In some instances, changes in chemical and physical properties of gas emissions, which are generated by geothermal systems connected to the volcanoes’ plumbing system, are important precursors of volcanic activity and useful indices for the study of the geothermal field. Furthermore, some superficial structures such faults, landslide slopes or archaeological relics should be studied with such a high detail that geophysical and bathymetric surveys are unable to provide. In response to the needs increasingly…