Search results for " Mach"
showing 10 items of 1388 documents
Assessment of Cost and Energy Requirements of Electron Beam Melting (EBM) and Machining Processes
2017
Additive Manufacturing is under the spotlight as potential disruptive technology, particularly for the production of complex-shaped structural metallic components. However, the actual AM process capabilities present some limitations in achieving the strict part quality requirements imposed by the aerospace and automotive sectors. Therefore, the integration of AM and conventional manufacturing represents an emerging scenario to be investigated. In this paper, a pure machining process and a hybrid production route (based on EBM and finish machining) are compared. The influence of material usage-related factors on costs and energy demand is discussed. The results prove that, despite precise pr…
A Banki–Michell turbine for in-line water supply systems
2017
The design of a novel Banki-Michell type turbine, to be located in existing water pipelines, is proposed. The turbine has a very efficient diffuser which allows the turbine to be compact and, most important, to have in-line flanges for minimal piping modifications at existing sites. This turbine combines a simple geometry with stable efficiency in a wide range of water discharges. The design procedure estimates the outer diameter of the impeller, its width and the geometry of the diffuser. A series of experimental tests has been carried out to measure the efficiency of the proposed turbine prototype. The turbine was tested in two different configurations, with and without rotational velocit…
VirDe: A new virtual reality design approach
2008
Virtual reality (VR), even if it does not represent any more a novel technology, is one of the most powerful tool to help designers during the development of new projects. This is proved by very numerous research activities related to this field. In this research, we have studied a new way to approach the development of a product. We present the ongoing development of a system, called VirDe, acronym of virtual design, which can allow the designers to perform the whole design process, from the modelling phase to the finite element method (FEM) simulation analysis, in a virtual reality environment. This new method allows remarkable time and money saving in the overall product design process, …
A novel hybrid model for air quality index forecasting based on two-phase decomposition technique and modified extreme learning machine.
2017
The randomness, non-stationarity and irregularity of air quality index (AQI) series bring the difficulty of AQI forecasting. To enhance forecast accuracy, a novel hybrid forecasting model combining two-phase decomposition technique and extreme learning machine (ELM) optimized by differential evolution (DE) algorithm is developed for AQI forecasting in this paper. In phase I, the complementary ensemble empirical mode decomposition (CEEMD) is utilized to decompose the AQI series into a set of intrinsic mode functions (IMFs) with different frequencies; in phase II, in order to further handle the high frequency IMFs which will increase the forecast difficulty, variational mode decomposition (VM…
Thermal stress analysis of different full and ventilated disc brakes
2015
During the braking phase, the heat produced by friction between pads and disc cannot be entirely dissipated. Consequently, the brake disc, especially if very hard braking occur, can accumulate large amounts of heat in a short time so producing high gradients of temperature on it. Under these conditions, functionality and safety of the brake system can be compromised. The object of this study is to investigate, under extreme working conditions, the thermomechanical behaviour of different brake rotors in order to evaluate their efficiency and stability and to identify any compromising weakness on them. In particular, by means of FEM thermo-mechanical coupled analyses, one full disc and three …
Fast procedure for the calculation of maximum slot filling factors in electrical machines
2017
This paper presents an algorithm for the calculation of maximum slot filling factor in electrical machines. The determination of whole wire cross section that occupy the area of a stator slot is very important in order to estimate the copper losses: The greater is the filling factor the lower are copper losses. The main goal of this paper is to define a simple algorithm for the determination of slot filling factors suitable for all type of slot profiles. The algorithm can be considered as an additional useful tool for the fast design of electrical machine windings.
Testing of cooperative tasks for Unmanned Aerial and ground platforms
2014
In the last years the Model Based Design for Unmanned Systems aided the safe and rational release of applications running on unmanned systems. In particular in this paper we focus on a hybrid methodology that merges Software in the Loop (SIL) and Model in the Loop (MIL) strategies for cooperative tasks performed by aerial and ground autonomous vehicles. The proposed work flow covers the design and testing of Ground Control Station (GCS) modelled by a finite state machine, the design and testing of navigation code running on UAV and UGV and the testing of cooperative missions. The work-flow is based on a realistic 3D physical simulator interfaced with Matlab-Simulink-Stafeflow. The proposed …
Application of latent nestling method using Coloured Petri Nets for the Fault Diagnosis in the wind turbine subsets
2008
This paper presents an application example using the lating nestling method for the fault diagnosis based in the use of coloured Petri nets, to a lubrication and cooling system in the wind turbinepsilas gearbox with a critical subsystem as far as failure probability. It demonstrate the synthesis capacity of the method for any model of diagnosis and isolation, giving as opposed to know the contributed advantages other methodologies, as those based in finite state machine.
Latent Nestling Method: A new fault diagnosis methodology for complex systems
2008
This paper presents a new methodology for permanent and intermittent fault diagnosis, named faults latent nestling method (FLNM), using coloured Petri nets (CPNs). CPNs and FLNM method allow for an enhanced capability for synthesis and modelling of complex systems in contrast to the classical phenomena of combinational state explosion when using finite state machine based methods.
Modular fault diagnosis based on discrete event systems for a mixer chemical process
2003
The knowledge of failure type and their location is an indispensable requirement for the establishment of tasks of adequate recovery strategies and maintenance of both factory automation and process control systems. The failure diagnosis methodology presented in the paper is based on discrete event systems models and on the diagnosers concept, those which permit the analysis off-line and online of diagnosability of failures that can occur in the processes. We present an approach for models and associated diagnosers based on a modular decomposition of the global system, with the purpose of avoiding the problems of the exponential explosion of the number of states and of the computational com…