1,722 research outputs found
Aumento dell'affidabilità e dell'efficienza del modello DFRM per simulare al propagazione di colate detritiche.
No full textIn the upper regions of mountain basins, landslides play a fundamental role in shaping the terrain and supplying sediment to channel flow. Within this frame, numerous processes must be considered, which include to rock collapses to sediment flow dynamics in the principal channels. Among the various types of landslides that can occur along these channels, one of the most perilous is the debris flow, a rapid surge of sediment and water mixed. Due to the flow's speed and its ability to transport big boulders at its impact front, debris-flows possess a high destructive potential. Other significant hazardous factors include the long distances they can cover and their sudden occurrence, sometimes without previous runoff in a channel.
Triggering occurs when there is a right combination of three main conditions: the channel slope; the runoff and the availability of sediment at the channel bottom and its susceptibility to movement. When runoff impacts sediment in the area where the channel slope is above a threshold, a debris flow may be triggered. However, the presence of sediment in the channel bottom is necessary for a triggering and closely linked to landslides occur in upper part of basin. Therefore, the connectivity of the sediment on basin’s slopes is important to the initialization of the flow transport. Consequently, debris flow is a natural phenomenon that is not easily predictable because local channel conditions are influenced by several processes. In addition, estimation of runoff through a hydrological model is not easy task, it requires right calibration using a good knowledge of the study area and a correct identification of the local rainfall volume. Sometime, these latter points are not easy to achieve in particular way in mountainous area. All of these concepts underscore the importance to study and developing models that help authorities in predicting and identifying the risk to human lives and activities. Especially because, areas with small slopes in the centre of the valley were considered the most suitable place to build, but sometimes these are deposition fans formed by sediments from debris-flow events.
Nowadays, numerical models are the main tools for identifying hazards and assessing risks. They play a crucial role not only in new project development but also in evaluating the effectiveness of existing countermeasures. Moreover, improving the knowledge on debris-flow initiation and propagation and their modelling becomes very important to reduce and control the risk in the subject area. The final goal of this research is to develop an efficient and reliable model that can be used both in the aforementioned fields and integrating in a model base early warning system
Curvature Effects on Permanent Magnet Harmonic Losses of Surface-Mounted Permanent Magnet Machines
No full textPermanent magnets mounted on the rotor (or mover) of surface-mounted permanent magnet (SPM) rotating (or linear) synchronous machines are exposed to armature reaction field magneto-motive force (MMF) space harmonics, which cause eddy currents and losses. Magnet losses in rotating machines are sometimes studied through simplified models where the air-gap geometry is linearized. This may lead to suppose that curvature plays a minor role. In order to verify the extent to which such assumption holds, explicit formulas are derived and assessed in this paper for magnet loss estimation in case of both linear and circular air-gap geometry. Then, magnet losses in rotating and linear machines having equal MMF harmonics, air-gap width and magnet height and material are compared and conclusions about curvature effects on permanent magnet losses are drawn
Proposed Solution for Stony Debris-Flow Control Works in Two Headwater Basins with Morphological Changes
No full textStony debris flows originating from the two basins of Jaron di Sacomedan and Jaron dei Ross pose a significant threat to the inhabited area of Chiapuzza (Dolomites, Northeastern Italian Alps) and the national road SS 51. In the upper part of the Jaron dei Ross basin, a large scree at the foot of a rocky amphitheater undergoes morphological changes due to frequent rockfalls. Previous mitigation efforts have proven inadequate, and after identifying the causes of their failure, new control measures are being planned. These works aim to direct debris flows towards a deposition area capable of intercepting flows from both the Jaron dei Ross and Jaron di Sacomedan basins. Essentially, the upper works in the Jaron dei Ross basin divert debris flows away from the populated area and channel them to a location where the sediment volume transported by debris flows from both basins can be stored. This solution is designed to protect both the Chiapuzza community and the SS51 national road
Utilizzo di un modello idraulico per colate detritiche nella progettazione di opere idraulico-forestali
No full textTUTELA DEL LAVORO E LIBERTA' D'IMPRESA NEI PROCESSI DI ESTERNALIZZAZIONE
No full textL’elaborato analizza le conseguenze lavoristiche della successione fra imprenditori, muovendo da una ricognizione delle varie tipologie di esternalizzazione con le relative esigenze e principali criticità.
L’indagine si concentra in primo luogo sul trasferimento d’azienda, esaminando la normativa e la giurisprudenza europee per passare poi alla disciplina di diritto interno, alle procedure sindacali e a uno specifico focus sul trasferimento delle aziende in crisi.
Successivamente l’autore si sofferma sull’appalto, prendendone in particolare considerazione gli indici di genuinità, i criteri di distinzione dalla somministrazione illecita di manodopera e la tutela delle maestranze in caso di avvicendamento fra imprese.
Da ultimo, la ricerca approfondisce le c.d. “clausole sociali”, sia di prima che di seconda generazione, valutandone la compatibilità con il diritto eurounitario e con la costituzione nonché riflettendo sui possibili rimedi in caso di loro violazione.The author analyzes the labour consequences of the succession between entrepreneurs, starting from a recognition of the various types of outsourcing with the related needs and main critical issues.
The survey focuses primarily on the transfer of businesses, examining European legislation and case-law and then moving on to internal legislation, trade union procedures and a specific focus on the transfer of companies in crisis.
The author then dwells on the contract, taking into account in particular the indications of authenticity, the criteria of distinction from the illicit administration of labour and the protection of workers in the event of turnover between companies.
Finally, the research deepens the "social clauses", both first and second generation, assessing their compatibility with European law and with the constitution and reflecting on possible remedies in case of their violation
Simulations of the occurrence of runoff-generated debris flows by means of hydrological models in headwater rocky basins
No full textThe simulation of the occurrence of the runoff-generated debris flows can be approached by means of hydrological models. In this work, we show that a rainfall-runoff model designed for the simulation of runoff in headwater rocky basins can capture both the transit timing of the first debris-flow surge and its hydrograph. We successfully compared the stage hydrograph of debris flows with that of the simulated runoff in two headwater rocky basins of Dolomites
Modello efficiente di propagazione idraulica di colate detritiche per realizzare mappe di pericolo
No full textStart-Up Performance Prediction of Line-Fed Solid-Rotor Salient-Pole Synchronous Motors
No full textSolid rotor synchronous motors are widely used in the Oil&Gas industry, because of their mechanical robustness and self-starting capability. The starting performance calculation for these machines is a challenging task. In this paper the specific case of a solid salient pole motor rated 17.5 MW at 1500 rpm is addressed. A simplified but accurate method is proposed and validated experimentally to predict the motor current and torque during direct-on-line (DOL) starting. The proposed methodology combines Finite Element Analysis (FEA) with a lumped-parameter machine model to obtain the best compromise between accuracy and computational efficiency
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