Diagnosis of Mechanical Faults Affecting a Hydroelectric Group by Vibration Analysis

This article deals with a diagnostic approach based on a predictive / conditional maintenance approach of a hydroelectric group. The technique used is based on the spectral analysis of the vibration signals, as well as on the orbital analysis of the bearings displacements. To do this, test protocols in different operating regimes are carried out, based on the collection of data measured according to the multisensor approach, the aim of which is to identify the predominant faults. The positions of the sensors are placed as close as possible to the bearings on the rigid structure of the hydroelectric group in accordance with the recommendations of standard ISO 10816-5. The evaluation approach is based on the analysis of the amplitudes of the vibration speeds, the aim of which is to identify the type of faults, as well as on the bearing displacement indicators in order to classify them in the pre-established zones according to thresholds recommended by the Standard. Therefore, a recommended tuning intervention can be planned in order to restore the unit to its proper operating condition, the aim of which is to increase its service life and improve fuel efficiency. Keywords—Diagnostic, Vibration analysis, Hydroelectric group, Multi-sensor approach, Standard

LOCAL DETERMINANTS OF DRIVING BEHAVIOURS: INSTALLATION THEORY INTERVENTIONS TO REDUCE FUEL CONSUMPTION AMONG TRUCK DRIVERS IN COLOMBIA

Eco-driving has been linked to considerable reductions in negative externalities and costs for transportation companies, employees and communities (including fuel consumption, safety and emission benefits). Nevertheless, some of the biggest challenges to its implementation are related to promoting behavioural change among drivers. This paper presents the results of three behavioural field interventions that were successful to improve fuel efficiency in heavy freight transportation. The interventions brought further improvement even though the target company already had strong training, incentive, control and feedback procedures in place. The Installation Theory framework and the Subjective Evidence-Based Ethnography (SEBE) technique were used to systematically analyse determinants of driving behaviours, and to design cost-effective behavioural interventions based on social norms. The effects of three interventions were then tested using a pre-test post-test control group design among 211 drivers of the company. Results show significant decreases in average monthly fuel consumption of up to 4% in month 1 and up to 4.5% in month 3. Our findings show (with certain qualifications), that the Installation Theory framework and social norm interventions can be a cost-effective method to improve fuel efficiency in road freight transport companies, even when strong training, incentive, control and feedback procedures are already in place.

Method to Reduce Drag Coefficient for Fuel Efficiency in Semi-Truck Trailer and Trailer Stability

Heavy commercial vehicles due to their un-streamlined body shapes are aerodynamically inefficient due to higher fuel consumption as compared to passenger vehicles. The rising demand and use of fossil fuel escalate the amount of carbon dioxide emitted to the environment, thus more efficient tractor-trailer design becomes necessary to be developed. Fuel consumption can be reduced by either improving the driveline losses or by reducing the external forces acting on the truck. These external forces include rolling resistance and aerodynamic drag. When driving at most of the fuel is used to overcome the drag force, thus aerodynamic drag proves an area of interest to study to develop an efficient tractor-trailer design. Tractor-trailers are equipped with standard add-on components such as roof defectors, boat tails and side skirts. Modification of these components helps reduce drag coefficient and improve fuel efficiency. The objective of this study is to determine the most effective geometry of trailer add-on devices in semi-truck trailer design to reduce the drag coefficient to improve fuel efficiency and vehicle stability. The methodology consisted of CFD analysis on Mercedes Benz Actros using ANSYS FLUENT. The simulation was performed on the tractor-trailer at a speed of 30m/s. The analysis was performed with various types of add-on devices such as side skirts, boat tail and vortex generators. From the simulation results, it was observed that addition of tractor-trailer add-on devices proved beneficial over modifying trailer geometry. Combination of add-on devices in the trailer underbody, rear and front sections was more beneficial in reducing drag coefficient as compared to their individual application. Improving fuel efficiency by 17.74%. Stability of the tractor-trailer is improved due to the add-on devices creating a streamlined body and reducing the low-pressure region at the rear end of the trailer.