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As commercial and military aircraft continue to be subject to direct lightning flashes, there is a great need to characterize correctly the electrical currents and electric potential fluctuations on an aircraft to determine alternative design approaches to minimizing the severity of the lightning-aircraft dynamics. Moreover, with the increased severity of thunderstorms due to global warming, the need arises even more to predict and quantify electrical characteristics of the lightning-aircraft electrodynamics, which is normally not measurable, using a reliable electric model of the aircraft. Such a model is advanced here. The paper aims to discuss these issues.

The case considered in this paper is that of an aircraft directly attached to an earth flash lightning channel. The paper develops a new approach to modelling the aircraft using electric dipoles. The model has the power to represent sharp edges such as wings, tail ends and radome for any aircraft with different dimensions by using a number of different sized dipoles. The distributed transmission line model (TLM) of the lightning return stroke incorporating the distributed aircraft model is used to determine aircraft electrical elements and finally the electric current induced on the aircraft body due to lightning's interaction with the aircraft. The model is validated by the waveform method and experimental results.

The dipole model proposed is a very powerful tool for minute representation of the different shapes of aircraft frame and to determine the best geometrical shape and fuselage material to reduce electric stress. This charge simulation method costs less computer storage and faster computing time.

The paper for the first time presents a computer-based simulation tool that allows scientists and engineers to study the dynamics of voltage and current along the aircraft surface when the aircraft is attached to a cloud to ground lightning channel.

The purpose of this paper is to design and realize a high gain power amplifier (PA) with low output back-off power using the InGaP/GaAs HBT process for WCDMA applications from 1.85 to 1.91 GHz.

A three stages cascaded PA is designed which observes a high power gain. A 100 mA of quiescent current helps the PA to operate efficiently. The final stage device dimension has been selected diligently in order to deliver a high output power. The inter-stage match between the driver and main stage has been designed to provide maximum power transfer. The output matching network is constructed to deliver a high linear output power which meets the WCDMA adjacent channel leakage ratio (ACLR) requirement of −33 dBc close to the 1 dB gain compression point.

With the cascaded topology, a maximum 31.3 dB of gain is achieved at 1.9 GHz. S11 of less than −18 dB is achieved across the operating frequency band. The maximum output power is indicated to be 32.7 dBm. An ACLR of −33 dBc is achieved at maximum linear output power of 31 dBm.

The designed PA is an excellent candidate to be employed in the WCDMA transmitter chain without the aid of additional driver amplifier and linearization circuits.

In this work, a fully integrated GaAs HBT PA has been implemented which is capable to operate linearly close to its 1 dB gain compression point.

The purpose of this paper is to investigate the heat transfer in an arbitrary cavity filled with porous medium. The geometry of the cavity is such that an isothermal heating source is placed centrally at the bottom of the cavity. The height and width of the heating source is varied to analyses its effect on the heat transfer characteristics. The investigation is carried out for three different cases of outer boundary conditions such as two outside vertical walls being maintained at cold temperature T_o, two vertical and top horizontal surface being heated to. T_o and the third case with top surface kept at T_o but other surfaces being adiabatic.

Finite element method is used to solve the governing equations.

It is observed that the cavity exhibits unique heat transfer behavior as compared to regular cavity. The cases of boundary conditions are found to affect the heat transfer rate in the porous cavity.

This is original work representing the heat transfer in irregular porous cavity with various boundary conditions. This work is neither being published nor under review in any other journal.

The purpose of this study was to analyze the heat transfer in a square porous cavity that has a solid block placed at its center. The prime focus of this study is to investigate the effect of size of the square solid block and other physical parameters on the heat transfer rate from the hot surface into the porous medium. The left vertical surface of cavity is maintained at a hot temperature and the right vertical surface at a cool temperature, T_c. The finite element method is used to simplify the governing equations and is solved iteratively. It is noted that the size of the solid block plays a vital role in dictating the heat transfer from the hot surface to porous medium.

The current work is based on finite element formulation of a square porous cavity that has a solid square block placed at its center. Governing equations were solved iteratively.

The size of the solid block has a pronounced effect on the heat transfer behavior inside the porous cavity.

This study highlights the heat transfer due to a conducting square solid block at mid of porous cavity.