Search results for "Mathematica"
showing 10 items of 7971 documents
Manufacturing tolerances effects on PV array energy production
2014
This paper investigates the tolerance effects of commercial photovoltaic modules in terms of electrical energy reduction of photovoltaic plants. Several commercial modules, having the same rated power, present different power tolerance values. A wide tolerance is an indicator of possible defects or differences in the production process and is responsible of remarkable reductions in the electricity production of photovoltaic plants. In this paper, thanks to the development of a suitable simulation tool, several simulations have been carried out, considering different tolerance and shading conditions for the PV array. Simulation results quantify the peak power value of the different plant con…
Mechanical construction and installation of the ATLAS tile calorimeter
2013
This paper summarises the mechanical construction andinstallation of the Tile Calorimeter for the ATLASexperiment at the Large Hadron Collider in CERN, Switzerland. The TileCalorimeter is a sampling calorimeter using scintillator as the sensitivedetector and steel as the absorber and covers the central region of the ATLASexperiment up to pseudorapidities ±1.7. The mechanical construction ofthe Tile Calorimeter occurred over a periodof about 10 years beginning in 1995 with the completionof the Technical Design Report and ending in 2006 with the installationof the final module in the ATLAS cavern. Duringthis period approximately 2600 metric tons of steel were transformedinto a laminated struc…
Plastic load capacity and stability of frames in fire
1997
The behaviour of real construction materials in different predictable conditions is so complex that it is difficult to describe it precisely in terms of mathematical equations. The problem of the mathematical modelling of materials is, therefore, to be solved rationally by taking into consideration the material type, construction method, load value and external conditions (e.g. temperature). In ambient temperatures there is an interaction of elastic form and plastic form of steelwork failure. This interaction is described by the Merchant-Rankine formula. An analogous interaction should be expected at elevated temperatures. This paper puts forward an interaction formula for elasto-plastic cr…
Spectral analysis of the criteria for multiaxial Random Fatigue
1991
In the paper the spectral analysis of several fatigue criteria under simple and complex states of stress has been done and limitations appearing while formulating new criteria for multiaxial random loadings have been shown. The presented analysis includes determination, with digital simulation, of probability density function and power spectral density function of the equivalent stress according to three special linear criteria of multiaxial random fatigue and six nonlinear criteria. Calculations were carried out for four kinds of random stress state. It has been shown that mathematical models for the criteria of multiaxial random fatigue formulated as nonlinear combinations of stress state…
Machining Economics and Optimization
2008
This chapter provides comprehensive knowledge regarding economical considerations and possible optimization methods of machining operations. The background of machining economics, including costs, time and productivity, related for typical machining operations (such as turning, milling and drilling) is outlined. The components of machining costs and time related to the cutting speed are distinguished, and appropriate mathematical models are presented. Optimization procedures allowing selection of optimal values of cutting speed and feed rate based on tool life and energy efficiency criteria are overviewed. In the first case, the economic cutting speed and cutting speed corresponding to the …
Electrostatic synchronous generator model of an Inverter-Based Distributed Generators
2015
In this paper, the idea of modelling the Inverter-Based Distributed Generators by using the concept of Electrostatic synchronous machines is discussed. A mathematical model of the inverter has been established which depends on the dc bus voltage, modulation index and frequency of the system. Two mathematical models have been developed: a small signal model and a steady-state model. These mathematical models will be helpful in studying the stability of a microgrid; especially when studying the transient stability performance of on-grid operation of converter-based distributed generator with multi-machine microgrid. Simulation results using Matlab/Simulink are carried out.
Mathematical Model of a PM Brushless Motor with Different Stator-Rotor Pole Pairs Number
2013
The paper presents a mathematical model of Permanent Magnet AC brushless machines (PMSM) having a number of stator poles-obtained via the distribution of the three-phase winding- different from the rotor one, realized by the displacement of the permanent magnets. For these so- called ‘Fractional-Slot’ motors (where few total slots generate high equivalent number of poles) the available mathematical models appear partial and/or incomplete, despite of numerous designing considerations made in literature. In this paper an analytical approach is developed to point out an instantaneous- values mathematical model with concentrated parameters, that can be suitable for control architecture systems …
APPLICATION OF MATHEMATICAL MODELS FOR THE SIMULATION OF THERMAL COMFORT CONDITIONS IN A LIVING ROOM
2005
The paper deals with the distributions of temperature and averaged turbulent airflows in living rooms in 2D and 3D approximations using Ansys/Flotran and Ansys/CFX software respectively. The distributions are calculated depending on the placement and temperature of heaters, heat transfer coefficients of the building structures and ventilation conditions. The authors analyse the influence of these factors on the air circulation and the related heat flows through building structures. The thermal balance of a room and its dependence on various external factors is also considered. As thermal comfort conditions’ parameters are analysed, the airflow velocities and indoor temperatures with its gra…
Validation Specimen for Contour Method Extension to Multiple Residual Stress Components
2007
A new theoretical development of the contour method [1], that allow the user to measure the three normal residual stress components on cross sections of a generic mechanical part, is presented. To validate such a theoretical development, a residual stress test specimen was properly designed, fabricated and then tested with different experimental techniques.
Intensive wave power and steel quenching 3-D model for cylindrical sample. Time direct and reverse formulations and solutions
2017
In this paper we develop mathematical models for three dimensional hyperbolic heat equations (wave equation or telegraph equation) with inner source power and construct their analytical solutions for the determination of the initial heat flux for cylindrical sample. As additional conditions the temperature and heat flux at the end time are given. In some cases we give expression of wave energy. In some cases we give expression of wave energy. Some solutions of time inverse problems are obtained in the form of first kind Fredholm integral equation, but others has been obtained in closed analytical form as series. We viewed both direct and inverse problems at the time. For the time inverse pr…