1,721,012 research outputs found
Laparoscopic-endoscopic surgical instrument for handling parenchymatous and cavum organs
No full textSTRUMENTO DA PRESA ATRAUMATICA A VENTOSA PER MANIPOLAZIONE DI ORGANI PARENCHIMATOSI E CAVI PER CHIRURGIA LAPAROSCOPICA ED ENDOSCOPICA
No full textAnalysis of Engine Braking System for Heavy Vehicle Performance Improvement
No full textThis paper focuses on the analysis of engine braking systems used in Internal Combustion Engines (ICEs) for heavy vehicles. It aims to evaluate the functionality of engine brakes and investigate the technologies used for their implementation. Engine braking is crucial for vehicle safety and efficiency since it reduces speed through the engine's mechanical resistances, thus saving energy, and limiting wear of friction brakes. While light vehicles typically downshift gears for engine braking, heavy vehicles use exhaust valve manipulation. Two diesel engines, E1 and E2 from FPT Industrial S.p.a., are analysed, each equipped with different engine brake types: mechanical for E1 and hydraulic for E2. The research activity involves component and system-level analysis, including thermal cycle examination, mechanical component performance evaluation, critical issue identification, and comparison of braking power characteristics. E2 demonstrates superior performance due to its fully hydraulic brake system, regulated by an Oil Control Valve (OCV), allowing quicker and more precise activation compared to E1. Additionally, E2 emits 9% less carbon dioxide, enhancing its competitiveness for future emissions regulations
On the Power-Weighted Efficiency of Multimode Powertrains: A Case Study on a Two-Mode Hybrid System
Full text linkMultimode powertrains represent one of the most versatile solutions for hybrid electric vehicles where multiple power sources are integrated with aim of improving fuel economy and reducing pollutants emission in every operating condition. Some hybrid powertrain designs feature multiple planetary gear sets whose components can be directly driven by the powertrain actuators (electric motor or thermal engine) or can be connected through clutches and brakes. The advantages due to the availability of multiple modes are mitigated by the increase of production costs and complexity because of the higher number of components required if compared with the single mode solutions. A numerical methodology is adapted from the literature to analyze, categorize, and compare each distinct working configuration. The energy consumption of each powertrain configuration is then evaluated through the power-weighted efficiency concept whose formulation normalize the contribution from each power source. This paper aims at extending the methodology to investigate the operating range for each powertrain configuration to always achieve the maximum efficiency. The methodology is then applied to the realistic case study of the EVT 2-Mode Hybrid System
Analytical study on the cornering behavior of an articulated tracked vehicle
Full text linkArticulated tracked vehicles have been traditionally studied and appreciated for the extreme maneuverability and mobility flexibility in terms of grade and side slope capabilities. The articulation joint represents an attractive and advantageous solution, if compared to the traditional skid steering operation, by avoiding any trust adjustment between the outside and inside tracks. This paper focuses on the analysis and control of an articulated tracked vehicle characterized by two units connected through a mechanical multiaxial joint that is hydraulically actuated to allow the articulated steering operation. A realistic eight degrees of freedom mathematical model is introduced to include the main nonlinearities involved in the articulated steering behavior. A linearized vehicle model is further proposed to analytically characterize the cornering steady-state and transient behaviors for small lateral accelerations. Finally, a hitch angle controller is designed by proposing a torque-based and a speed-based Proportional Integral Derivative (PID) logics. The controller is also verified by simulating maneuvers typically adopted for handling analysis
Logica fuzzy nella pneumatica
No full textIn this paper the most recent applications of fuzzy logic to pneumatic systems are presented. In particular, pneumatic actuators with position, speed and force control are examined, together with Cartesian robots with pneumatic drives and fuzzy control
Steering Behavior of an Articulated Amphibious All-Terrain Tracked Vehicle
Full text linkThis paper presents a study related to an Articulated Amphibious All-Terrain Tracked Vehicle (ATV) characterized by a modular architecture. The ATV is composed by two modules: The first one hosts mainly the vehicle engine and powertrain components, meanwhile the second one can be used for goods transportation, personnel carrier, crane and so on. The engine torque is transmitted to the front axle sprocket wheel of each module and finally distributed on the ground through a track mechanism. The two modules are connected through a multiaxial joint designed to guarantee four relative degrees of freedom. To steer the ATV, an Electro Hydraulic Power System (EHPS) is adopted, thus letting the vehicle steerable on any kind of terrain without a differential tracks speed. The paper aims to analyze the steady-state lateral behavior of the ATV on a flat road, through a non-linear mathematical vehicle model built in Matlab/Simulink environment. The model describes the vehicle main planar motion and the interaction between the two modules through the application of a hydraulic steering torque. The model simulates steady-state handling maneuvers in Matlab/Simulink. Two scenarios are considered: One with the application of an open-loop hydraulic steering torque without any vehicle feedback; the second one with a closed-loop steering torque actuation based on the relative angle between the two modules (hitch angle). Finally, the influence of the ATV longitudinal speed on vehicle lateral characteristics is also presented
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