Ghulam Ishaq Khan Institute of Engineering Sciences and Technology

About: Ghulam Ishaq Khan Institute of Engineering Sciences and Technology is a education organization based out in Topi, Pakistan. It is known for research contribution in the topics: Thin film & Quantum efficiency. The organization has 618 authors who have published 940 publications receiving 10674 citations.

Sum Ergodic Capacity Analysis Using Asymptotic Design of Massive MU-MIMO Systems

Abstract: This communication attempts to characterize the performance metrics of downlink Massive MU-MIMO systems impaired by cochannel interference and additive noise over a Rayleigh fading environment. We obtain close-form solutions for the probability density function of signal-to-interference-plus-noise ratio (SINR) and the sum ergodic capacity. The proposed work structures SINR in a quadratic form and thereby imposes a condition on its signal and interference power for a large transmit antenna diversity order; the conditional form is then analyzed using a distance correlation metric. Eventually, the sum ergodic capacity is expressed in a close-form by means of a residue theory approach and validated using the Monte Carlo simulation means.

Parametric study of gasketed flange joints of different sizes and classes for improved design and performance

Abstract: Gasketed bolted flanged pipe joints are widely used in industrial applications and are prone to failure in terms of sealing and strength. In this paper, flange bending stress, flange rotation, bolt bending, stress variation at gasket and centring ring of the gasketed flange joints are analysed during bolt up and internal pressure loading. Three pressure classes 150# (12-600 mm (0.5-24 in.)), 900# (12-600 mm (0.5-24 in.)) and 2500# (12-300 mm (0.5-12 in.)) were employed for comparison of results. For better joint strength and sealing, the bolts were prestressed to 50% of their yield strength during bolt-up and 20% surface yielding is allowed at the hub-flange fillet. In addition, raised face on the flange faces are machined to control flange rotation and bolt bending and achieve required gasket seating stress.

Minimizing energy losses by introducing periodic pinning centers on superconducting films

Abstract: We study vortex behavior in a set of samples of a rectangular array of antidots on a high-quality metallic superconducting Nb film. For this purpose, we measure magneto-resistance properties of some samples with varying dimensions, and also varying periods of antidots in the array. In the first phase, we characterize magneto-resistance curves of the samples with large period having weak pinning effect. The vortex array, due to the interstitial vortices being dominant, rapidly becomes disorder causing high differential resistance. Later, we measure the same curves with smaller period of the samples, and observe a strong pinning effect mainly due to the fact that the vortex array remains in order. We demonstrate that by decreasing the period of samples, energy loss in nano-engineered thin films may be minimized.

Experimental and Numerical Investigation of Solitary Wave Run-up Reduction

Abstract: Rehman, K.; Park, K.-Y., and Cho, Y.-S., 2018. Experimental and Numerical Investigation of Solitary Wave Run-up Reduction. In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Special Issue No. 85, pp. 1111–1115. Coconut Creek (Florida), ISSN 0749-0208.Rising sea-levels and extreme wave events threaten coastal communities and stability of coastal regions. Accurate prediction of wave over-topping over coastal protection structures is challenging, but vital for effective hazard mitigation. Non-hydrostatic numerical modelling and laboratory experiments are used to assess magnitude of run-up over coastal protection structures under varying relative wave heights and structural features. The primary focus is the investigation of solitary wave impact with breakwaters, the consequent run-up and measures for its reduction. The experiments consisted of generating solitary waves in a 1.1 m high and 32.5 m long flume and observing its run-up for different heights of incident waves. A slope adjuster was used to vary the slope of a plywood plank for reproducing coastal features. Experimental observations were verified by proposing a numerical model based on non-linear shallow water equations (NLSWE) and solution is obtained by Godunov-type finite volume method. The NLSWE provide good approximation of shoaling, wave breaking, and wave reflection which arise due to wave overtopping in the swash and surf zones. The novel feature of the numerical model is the introduction of bed slope discretization technique – applicable on both structure and unstructured meshes- which offers well-balanced solution even for steep slopes encountered in case of breakwaters. Shock-capturing capabilities of Harten, Lax, and van Leer with contact wave restoration (HLLC) solver are utilized for accurate estimation of shocks and bore waves features during flow transitions. The proposed model gives excellentn agreement with experimental observations. The findings will further enhance the understanding of extreme wave propagation events over submerged coastal structures and related mitigation techniques.