Search results for "Ground"

Mathematical Model of Unmanned Aircraft In Ground Effect for Optimal Collision Avoidance

2011

The fundamental aim of the present paper is to model the aerodynamic characteristics of an Unmanned Aerial Vehicle(UAV) flying in ground effect. The second aim is to determine the relationship between the optimal avoidance maneuver and the control to execute it. In fact, this relationship is basilar to the development of a guidance scheme capable of approximating the optimal trajectory in real time. In the first part of this work ,a non-linear model is built in order to model the aerodynamic characteristics of an UAV flying In Ground Effect. To use a single model in the whole range of flying altitude, aerodynamic coefficients are modeled by means of hyperbolic equations. In particular, thes…

An Improved Approach to the Simulation of Single-Line-to-Ground Faults in Transmission Networks

2009

These paper presents a mathematical model for studying the Single-Line-to-Ground fault in transmission networks, giving a personal contribution for a methodical and accurate analysis of complex systems, by providing an evolution of the “circuital method” able to solve the case of a system in which more than one line supply the fault.

Extraction of thermal characteristics of surrounding geological layers of a geothermal heat exchanger by 3D numerical simulations

2016

Ground thermal conductivity and borehole thermal resistance are key parameters for the design of closed Ground-Source Heat Pump (GSHP) systems. The standard method to determine these parameters is the Thermal Response Test (TRT). This test analyses the ground thermal response to a constant heat power injection or extraction by measuring inlet and outlet temperatures of the fluid at the top of the borehole heat exchanger. These data are commonly evaluated by models considering the ground being homogeneous and isotropic. This approach estimates an effective ground thermal conductivity representing an average of the thermal conductivity of the different layers crossed by perforation. In order …

Efficiency improvement of a ground coupled heat pump system from energy management

2011

The installed capacity of an air conditioning system is usually higher than the average cooling or heating demand along the year. So, most of the time, the system is working under its actual capacity. In this contribution, we study the way to improve the efficiency of a ground coupled heat pump air conditioning system by adapting its produced thermal energy to the actual thermal demand. For this purpose, an air conditioning system composed by a ground coupled heat pump and a central fan coil linked to an office located in a cooling dominated area was simulated, and a new management strategy aiming to diminish electrical consumption was developed under the basic constraint that comfort requi…

The influence of ozone and aerosols on the experimental values of UV erythemal radiation at ground level in Valencia

2009

Ultraviolet erythemal radiation (UVER) values have been simulated for different values of column ozone and aerosol optical depth (AOD) using a multiple scattering model: SBDART. The results show that UVER decreased when atmospheric ozone and aerosols increased, with the ozone having greater influence than AOD. To quantify these dependencies the influence of aerosols on the simulated values of UVER has been analysed for different ozone values. This dependence was linear. Similarly, to quantify the influence of ozone on the UVER values this was simulated for fixed values of AOD while varying the column ozone. The expression of this dependence was found to be a second-order polynomial. We also…

Experimental values of the UV index during 2000 at two locations in Mediterranean Spain

2002

During the past 2 years automatic measurements of UVB solar irradiance have been made sstematically at ground level at a number of points in Spain. Values for both the ultraviolet erythemal radiation and the ultraviolet index (UVI) have been obtained from these measurements. In this paper we present a first analysis of these values for two locations on the Spanish Mediterranean coast—Valencia and Barcelona—an area where a large part of the summer tourism of the country is concentrated. During the summer the UVI only reached ten on three occasions, though a value of nine was reached repeatedly (both classified as extreme risk by the World Health Organization). It has been shown that, in 90% …

Deperturbation treatment of theAΣ+1–bΠ3complex of NaRb and prospects for ultracold molecule formation inXΣ+1(v=0;J=0)

2007

High resolution Fourier transform spectra (FTS) of laser induced fluorescence (LIF) of $C\phantom{\rule{0.2em}{0ex}}^{1}\ensuremath{\Sigma}^{+};D\phantom{\rule{0.2em}{0ex}}^{1}\ensuremath{\Pi}\ensuremath{\rightarrow}A\phantom{\rule{0.2em}{0ex}}^{1}\ensuremath{\Sigma}^{+}--b\phantom{\rule{0.2em}{0ex}}^{3}\ensuremath{\Pi}$ and $A\phantom{\rule{0.2em}{0ex}}^{1}\ensuremath{\Sigma}^{+}--b\phantom{\rule{0.2em}{0ex}}^{3}\ensuremath{\Pi}\ensuremath{\rightarrow}X\phantom{\rule{0.2em}{0ex}}^{1}\ensuremath{\Sigma}^{+}$ transitions in ${\mathrm{Na}}^{85}\mathrm{Rb}$ and ${\mathrm{Na}}^{87}\mathrm{Rb}$ were obtained. An analysis of the direct LIF spectra together with the rotational relaxation satellite…

Laser synthesis of ultracold alkali metal dimers: optimization and control

2015

Effect of steel collars on the seismic behaviour of axially-cracked historical stone columns

2014

Granite and heavy stone circular columns could often be found in the cultural heritage among ancient churches and historical buildings in all the Mediterranean area. Their good strength properties allow them to carry big load values, while their bright colours and aesthetical characteristics were used by a lot of architects in the past to achieve structural solutions with great visual impact.Though such materials have great compressive strength values, environmental effects, especially long term effects, can damage the structural members, by cracking them. In this way the slenderness of the column increases, and the presence of an imposed ground motion can be very dangerous, since the colum…

Amplification of Interstory Drift and Velocity for the Passive Control of Structural Vibrations

2008

Mitigation of structural damage due to earthquake ground motion may be performed by inserting dampers in the structure. In order to enhance the damping effect various toggle brace configurations have been recently proposed. In this paper these equipments are analyzed in detail and compared with a new one here proposed. The analysis is performed by taking into account the inherent nonlinearities of the damper by means of stochastic analysis and validated by using time histories of recorder accelerograms and by the stochastic analysis using spectrum consistent power spectral density.