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Almost 80% of World's energy needs are furnished through combustion of natural resources such as oil, natural gas and coal etc. A sprawling world population implies increased demand of the energy resources. Subsequently, there has been a hike in fuel prices. Unfortunately, the planet is left to bear the brunt in form of pollution. These factors have put forward a pressing demand of research for eco-friendly...
This paper presents the half-duplex coded-cooperative scheme for non-line of sight communication systems. Multiple-relays are divided in two groups which are frequency division multiplexed and participate in coded-cooperation. Antenna array is used at the destination to obtain multi-receive diversity. Maximal ratio combining (MRC) is used at the destination to combine the signals transmitted at different...
This paper reports design, fabrication and measurements of a wideband amplifier for UHF applications. A technology based on Gallium Nitride (GaN) transistor is used to design a class- AB amplifier with compact dimensions which can be employed as a driver stage for many UHF applications with wideband requirements. Wideband impedance transformers at input and output of the amplifier are implemented...
Landing Craft Unit (LCU) is a specialized craft used to transport battle tanks, military vehicles and troops from a principal platform at sea to shore. There has been an increasing emphasis on shallow water operations in last decade. The capabilities of available LCUs limit the tactics of an amphibious operation. This study is focused on a newly proposed concept of High Speed Landing Craft Unit based...
Nuclear Submarines (SSNs) and Conventional Submarines (SSKs) have traditionally been approached with entirely different design philosophies. SSN designs are typically ocean going and offer endurance limited only by stores and crew. SSK designs, whilst traditionally smaller than SSN designs, are capable of operations in littoral waters and deploy low signature propulsion systems compared to SSN boats...
Super Wideband (SWB) printed antenna with enhanced gain covering the impedance bandwidth ranging from 3–20GHz is presented. Gain enhancement of the antenna is achieved using appropriately designed frequency selective structure (FSS) acting as a band stop filter i.e. reflector, while keeping the bandwidth of antenna unchanged. The FSS used effectively reflects the in-phase radiations with a very low...
Adaptive equalizer is an integral component of modern communication systems that combats the effects of channel fading especially in multipath environment. In long term evolution (LTE) the number of multipath are standardized as seven and nine for extended pedestrian and extended vehicular-A channel respectively. The number of filter taps is an important design parameter that determines the performance...
Recently, a low cost and reliable remote sensing infrastructure has emerged as one of the fundamental requirements for communication in sensor nodes of Cognitive Radio (CR) applications. To achieve this, an Energy Efficient Wireless Sensor Network (EEWSN) has significant importance for monitoring the entire CR Network (CRN). The foremost important aspect in CRN is the spectrum sensing for which different...
This paper presents the design of an implemented prototype of a multi-rate Continuous Phase Frequency Shift Keying (CPFSK) transmitter. In case of a fixed rate CPFSK transmitter, the input symbol rate remains constant, thus the pulse shaping filter and frequency deviation are also fixed to a certain bandwidth. Contrary to this, for a multirate CPFSK design, the input symbol rate may vary and the pulse...
The anomalistic aerodynamic behavior of wrap-around fins has kept the researchers engrossed in devising new design methods and analysis techniques. Rolling moment at zero incidence angle, induced forces and moments due to fin curvature, roll reversal phenomenon, static side moment and Magnus side moment are the main aggravations that make their aerodynamics more complex when compared with the planar...
Shock wave/boundary layer interaction with separation may induce large-scale instabilities involving the whole field. This phenomenon, known as transonic buffeting, causes potentially dangerous vibrations, negative effect on flight stability and reduces the lifetime of aircraft structures. In the present work, numerical simulations have been performed to investigate the buffeting phenomenon over a...
In order to investigate the viability to extract energy from fluid-structure interaction as the result of aeroelastic instability, we numerically compute the canonical problem of flow past a circular cylinder. The structure is modeled as elastically mounted, supported by linear spring and damper, where it is allowed to move in transverse direction only. The fluid flow is governed by non-dimensional...
This paper aims to evaluate the detection capability of three different beamforming techniques namely Bartlett, MUSIC, and 2D-FFT. MATLAB simulations of these techniques have been developed and applied on real-time data acquired through a linear sensor array. The simulation results and data analysis showed that 2D-FFT beamforming technique provides the best possible detection as compared to other...
Dynamic soaring is a cyclic manoeuvre practiced by RC glider pilots and marine avian species which utilises wind gradients on the leeward side of geophysical features to increase flight speed. The technique has been characterized by extraordinary lift during the climbing phase and tremendous gain of speed during the descent phase of the manoeuvres. The phenomenon experienced by these aircraft with...
An experimental study, at ReD= 1.3×103, has been performed to study the effects of placement of boundary-layer-submerged divergent vane-type vortex generator in the upstream symmetric region of a main cylinder at a gap of 0.75D on laminar junction flow. The study is performed using 2D Particle Image Velocimetry (PIV). Resultsof the experiment demonstrate the ability of this controlling method to mitigate...
A spike attached to a blunt body influence aerodynamic drag and changes its flow field in hypersonic flow. In other words, spiked hemispherical design minimize the drag and ensures longer ranges and more cost-effective flights. It is, therefore, a potential candidate for drag reduction of a future high-speed vehicle. The pressure on the blunt body can be substantially reduced due to forward facing...
Multivariate interpolation by using radial basis functions (RBF) provides persuasive meshfree method for scattered data approximation. It offers a unified solution for mesh motion and fluid-structure interpolation problems. The method is computationally expensive in its pure form, therefore, it has been combined with a data reduction “double-edged greedy” algorithm to make it efficient for large degrees...
A conceptual design approach has been described for a back-packable, hand-launched miniature unmanned aerial vehicle. The design space has been segregated into different areas that are analyzed separately in detail. The initial design phase involves an intellectual process and requires a number of design iterations to be performed. Therefore, low fidelity analyses tools are mostly employed to acquire...
Ceiling fans are the most used resource for providing indoor thermal comfort in hot climates because of factors like low cost, easy availability and less electric consumption compared to air conditioning units. The fan industry of Pakistan is well-renowned on the national scale. In this paper, the features of the flow field generated by the ceiling fans under different geometric shapes are discussed...
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