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.

A new transmission model in cognitive radio based on cyclic generalized polynomial codes for bandwidth reduction

Abstract: The frequency spectrums are inefficiently utilized and cognitive radio has been proposed for full utilization of these spectrums. The central idea of cognitive radio is to allow the secondary user to use the spectrum concurrently with the primary user with the compulsion of minimum interference. However, designing a model with minimum interference is a challenging task. In this paper, a transmission model based on cyclic generalized polynomial codes discussed in [2] and [15], is proposed for the improvement in utilization of spectrum. The proposed model assures a non interference data transmission of the primary and secondary users. Furthermore, analytical results are presented to show that the proposed model utilizes spectrum more efficiently as compared to traditional models.

Understanding Variations in the Tracking and Erosion Performance of HTV-SR-Based Composites due to AC-Stressed Aging.

Abstract: Among the polymeric family, high-temperature-vulcanized silicone rubber (HTV-SR) is the most deployed material for high voltage insulation applications. However, in an outdoor environment, due to contamination and wetting-induced dry band arcing, consequently SR experiences surface tracking and erosion. From a practical standpoint, the tracking and erosion performance under multi-stress aging is required to be known. It is in that context that the present study was undertaken to measure and analyze the effect of multi-stress aging on tracking and erosion performance. Composite samples of SR having different filler concentrations of silica and alumina trihydroxide (ATH) were aged in a multi-stress chamber for a period of 5000 h, and after that their electrical tracking performance was studied. Simultaneously, unaged samples were also exposed to tracking test for comparison. To conduct this test, the inclined plane testing technique was used in accordance with IEC-60587. All samples exposed to tracking test were analyzed using different diagnostic and measuring techniques involving surface leakage current measurement, Fourier transform infrared spectroscopy (FTIR), thermal stability and hydrophobicity classification. Experimental results shown that the tracking lifetime increased through incorporation of silica and ATH fillers in the SR. Amongst all test samples, two samples designated as filled with 2% nano silica and 20% micro silica/ATH exhibited greater resistance to tracking. This was attributed to the optimum loading as well as better dispersion of the fillers in the polymer matrix. The presence of nano-silica enhanced time-to-tracking failure, owing to both improved thermal stability and enhanced shielding effect on the surface of nanocomposite insulators.

Evaluation of Effectiveness of Fence on a Country’s Border: a Case Study of Pak-Afghan Border Fence

Abstract: The border fencing has become a hot topic in the world’s current political affairs. At the end of the Cold War, there were only 15 walls all around the world, but now, 70 such barriers are protecting the countries from the terrorists ( https://www.usatoday.com/story/news/world/2018/05/24/border-walls-berlin-wall-donald-trump-wall/553250002/ ), drug cartels, insurgents, or suicide bombers lurking on the other side. For the past two decades, the peace of Pakistan has been extremely deteriorated by the suicide bombers mainly coming from Afghanistan through Pak-Afghan Border. Recently, the government of Pakistan decided to build a border fence around the border. In this study, the effectiveness of this border fencing is determined in terms of its ability to stop terrorism, smuggling, and illegal immigration. The multi-criteria decision-making (MCDM) approach such as the fuzzy technique of order of preference by similarity to ideal solution (Fuzzy TOPSIS) is employed to determine the effectiveness of the border to stop terrorism, smuggling, and illegal immigration. The data for this study is collected from the army officers who worked at the Pak-Afghan Border. The results of Fuzzy TOPSIS depict that the most influencing factor is terrorism while the second most affected factor (alternative in this case) is smuggling. The third factor is illegal immigration which has the lowest weightage of importance among all the alternatives. The results of this study can be helpful for countries such as Pakistan that are facing the problems related to terrorism, smuggling, and illegal immigration from the neighboring countries in taking a decision to build border fencing.

Fast recursive reconstruction of large time varying multidimensional fields

Abstract: We develop computationally fast and storage efficient implementations for the Kalman-Bucy filter (KBf) for data assimilation problems with large time varying multidimensional fields. We refer to them as the block KBf (bKBf) and the localized block KBf (lbKBf). For fields defined on a 2D lattice of linear dimension I, the bKBf reduces the computational complexity of the KBf by O(I). The lbKBf saves further on computations by a factor of I and decreases the storage requirements by O(I). We illustrate the IbKBf in assimilating satellite measurements in physical oceanography, presenting simulations for an equatorial beta plane.

A Novel Efficient Traffic Estimation Strategy Using Hello Messaging Through Local Link Connectivity in MANETs

Abstract: Network traffic estimation under random mobility of network nodes is one of the key challenges for effective communication in mobile ad hoc networks (MANETs). Under random movement of network nodes and uniform distribution of path durations among neighboring nodes, there must be a unified model to determine an adequate network traffic estimation strategy in MANETs. In this paper, a local link connectivity model that guarantees effective communication among the neighboring nodes inside a cluster is presented. Furthermore, a novel efficient traffic estimation (ETE) strategy is presented using a Markov chain process and Hello messaging through local link connectivity among neighboring nodes under uniform speed and random trajectories of mobile nodes. It has been observed that the ETE strategy is affected by the transmission rate of Hello messages, link probability at current time step of the Markov process, expected number of nodes inside a cluster, received signal strength, and probability of successful reception of the expected Hello messages at next time step of the Markov process. An expected increase in the critical transmission range of a network node as a result of possible overlapping with its neighboring nodes inside the cluster due to random mobility has also been investigated. Analytical and simulation results demonstrate efficacy of the proposed ETE strategy in terms of successful reachability of transmitted Hello messages, mean connection time, mean CH degree, queuing delay, and load balancing. In addition, the ETE strategy achieves better local link connectivity among neighboring nodes, lower Hello messages transmission latency, and better throughput in terms of successful reception of Hello messages by a neighboring node.