Search results for: F. Tofighi
Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 3

Search results for: F. Tofighi

3 Receive and Transmit Array Antenna Spacingand Their Effect on the Performance of SIMO and MIMO Systems by using an RCS Channel Model

Authors: N. Ebrahimi-Tofighi, M. ArdebiliPour, M. Shahabadi

Abstract:

In this paper, the effect of receive and/or transmit antenna spacing on the performance (BER vs. SNR) of multipleantenna systems is determined by using an RCS (Radar Cross Section) channel model. In this physical model, the scatterers existing in the propagation environment are modeled by their RCS so that the correlation of the receive signal complex amplitudes, i.e., both magnitude and phase, can be estimated. The proposed RCS channel model is then compared with classical models.

Keywords: MIMO system, Performance of system, Signalcorrelation, SIMO system, Wireless channel model.

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2 Effect of Fuel Spray Angle on Soot Formation in Turbulent Spray Flames

Authors: K. Bashirnezhad, M. Moghiman, M. Javadi Amoli, F. Tofighi, S. Zabetnia

Abstract:

Results are presented from a combined experimental and modeling study undertaken to understand the effect of fuel spray angle on soot production in turbulent liquid spray flames. The experimental work was conducted in a cylindrical laboratory furnace at fuel spray cone angle of 30º, 45º and 60º. Soot concentrations inside the combustor are measured by filter paper technique. The soot concentration is modeled by using the soot particle number density and the mass density based acetylene concentrations. Soot oxidation occurred by both hydroxide radicals and oxygen molecules. The comparison of calculated results against experimental measurements shows good agreement. Both the numerical and experimental results show that the peak value of soot and its location in the furnace depend on fuel spray cone angle. An increase in spray angle enhances the evaporating rate and peak temperature near the nozzle. Although peak soot concentration increase with enhance of fuel spray angle but soot emission from the furnace decreases.

Keywords: Soot, spray angle, turbulent flames, liquid fuel.

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1 The Risk Assessment of Nano-particles and Investigation of Their Environmental Impact

Authors: Nader Nabhani, Amir Tofighi

Abstract:

Nanotechnology is the science of creating, using and manipulating objects which have at least one dimension in range of 0.1 to 100 nanometers. In other words, nanotechnology is reconstructing a substance using its individual atoms and arranging them in a way that is desirable for our purpose. The main reason that nanotechnology has been attracting attentions is the unique properties that objects show when they are formed at nano-scale. These differing characteristics that nano-scale materials show compared to their nature-existing form is both useful in creating high quality products and dangerous when being in contact with body or spread in environment. In order to control and lower the risk of such nano-scale particles, the main following three topics should be considered: 1) First of all, these materials would cause long term diseases that may show their effects on body years after being penetrated in human organs and since this science has become recently developed in industrial scale not enough information is available about their hazards on body. 2) The second is that these particles can easily spread out in environment and remain in air, soil or water for very long time, besides their high ability to penetrate body skin and causing new kinds of diseases. 3) The third one is that to protect body and environment against the danger of these particles, the protective barriers must be finer than these small objects and such defenses are hard to accomplish. This paper will review, discuss and assess the risks that human and environment face as this new science develops at a high rate.

Keywords: Nanotechnology, risk assessment, environment.

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