Search results for "SPEED"
showing 10 items of 876 documents
On Serving Cell Change Reliability in HSDPA Network
2009
In Wideband Code Division Multiple Access (WCDMA) networks the Signaling Radio Bearer (SRB) is transmitted downlink to inform the user i.a. when it needs to make a handover. When transmitting e.g. Voice over IP (VoIP) on High Speed Downlink Packet Access (HSDPA) SRB is mapped on HSDPA user data channel, High-Speed Downlink Shared Channel (HS-DSCH) in order to maximize voice capacity. The lack of support for soft handover (SHO) of HS-DSCH may compromise the reception of SRB and thus also a possible incoming serving HSDPA cell change command especially at the cell borders. This can lead to serious VoIP service degradation due to prolonged camping on a poor cell and in the worst case even to c…
The bridge volcanic LIdar-BILLI: A review of data collection and processing techniques in the Italian most hazardous volcanic areas
2020
Volcanologists have demonstrated that carbon dioxide (CO2) fluxes are precursors of volcanic eruptions. Controlling volcanic gases and, in particular, the CO2 flux, is technically challenging, but we can retrieve useful information from magmatic/geological process studies for the mitigation of volcanic hazards including air traffic security. Existing techniques used to probe volcanic gas fluxes have severe limitations such as the requirement of near-vent in situ measurements, which is unsafe for operators and deleterious for equipment. In order to overcome these limitations, a novel range-resolved DIAL-Lidar (Differential Absorption Light Detection and Ranging) has been developed as part of…
Numerical and experimental study of hydrostatic displacement machine
2012
This paper presents a simulation tool to determine the structural deflections and corresponding leakage flow in a hydrostatic displacement motor. The simulation tool is applied to a new motor principle that is categorized as an extreme low-speed high-torque motor with dimensions that calls for attention to the volumetric efficiency. To counteract structural deflections the motor is equipped with compensation pressure volumes that may be used to limit the leakage flow across the end faces of the circular rotor. This leakage flow is investigated by solving Reynolds equation for the pressure distribution across both end faces. The fluid pressure is combined with structural calculations in a fl…
Real-time acquisition of complex optical fields by binary amplitude modulation
2017
We describe, through simulations and experiments, a real-time wavefront acquisition technique using random binary amplitude masks and an iterative phase retrieval algorithm based on the Fresnel propagator. By using a digital micromirror device, it is possible to recover an unknown complex object by illuminating with this set of masks and simultaneously recording the resulting intensity patterns with a high-speed camera, making this technique suitable for dynamic applications.
A methodology for evaluation of operational zones for distributed generation based on DFIG
2017
This study developed a methodology to determine zones of acceptable voltage profiles for wind power generation connected to distribution systems. Three load profiles (residential, commercial and industrial) connected to the distribution network were analyzed considering the impact on voltage levels and steady-state stability for different wind speeds and wind generator control strategies. The wind generator model is based on doubly fed induction generator (DFIG) and were developed using Matlab/Simulink. The presented methodology can be used to map the impact on operation of different types of control, the time of day and the available wind speed and it is not limited only for DFIG. The resu…
Applying Numerical Weather Prediction Models to the Production of New European Wind Atlas : Sensitivity studies of the wind climate to the planetary …
2018
Reliable and precise information about the wind speed climate is crucial for the development of wind energy. Meteorological processes in the mesoscale (2 – 200 km) can be represented using Numerical Weather Prediction (NWP) models such as the Weather Research and Forecast model (WRF), but before their application for creating wind energy atlases, their results and sensitivity to modelling parameters should be investigated. Here the WRF model wind speed results for the year 2015 for the Baltic Sea region are investigated, and the effect of the planetary boundary layer parametrization scheme is analyzed.
Numerical and analytical analysis of a monopile-supported offshore wind turbine under ship impacts
2021
Abstract Offshore wind turbines in the vicinity of ship traffic are exposed to increased risks of ship collisions. To better understand the impact mechanism, this paper evaluates the dynamic responses of a monopile-supported wind turbine under ship impacts, using both numerical and analytical methods. The nonlinear finite element method is applied during the numerical simulations, and the wind load effects, soil conditions, and rigid and deformable ship bows are considered. The analytical approach, originally developed based on the energy method, is extended here to address the damping effects of monopile-supported wind turbines. In the case study, the impacts are studied between a 4600-ton…
Verification of Numerical Weather Prediction Model Results for Energy Applications in Latvia
2014
Abstract Wind power forecasting greatly relies on wind speed forecasts. Numerical Weather Prediction (NWP) models are a reliable source of meteorological forecasts and they can also be used in wind resource assessment. In this work we carry out the verification of wind speed results from the NWP model Weather Research and Forecast (WRF), grid resolution - 3 km. Results from 172 model runs in May and November 2013 are compared with meteorological observations in 24 stations in Latvia. The model usually predicts wind speed values that are larger than the observed and the diurnal cycle has a large impact on verification results. Verification results obtained by interpolating model results betw…
Wind speed spatial estimation for energy planning in Sicily: introduction and statistical analysis
2008
Abstract The exploitation of the renewable energy sources plays a key role for achieving the CO 2 emissions reduction targets established by the Kyoto Protocol, as well as for facing the shortage of world fossil fuels reserves. In countries like Italy, with an high potential in terms of wind power generation, an efficient energy planning based on renewables is a very complex task. It encompasses many aspects: the resource availability assessment, the compliance with environmental and legislative constraints and last, but not least, the technical aspects linked to the safe integration to the grid of the intermittent power generated by the wind farms. This paper is the first part of a study a…
Joint probability distributions for wind speed and direction. A case study in Sicily
2015
In this study we analyze data of hourly average wind speed and direction measured at three different sampling stations located in Sicily (Italy) and provide a statistical model for their joint probability density function. Singly truncated from below Normal Weibull mixture distribution and a linear combination of von Mises distributions are used to model wind speed and direction. Sites with heterogeneous local conditions (prevailing wind direction and/or elevation) have been considered in order to investigate the reliability of the model here taken into consideration.