31 research outputs found

    Integration of a genetic optimisation algorithm in a simulation framework for optimising femtocell networks.

    Get PDF
    The developments in mobile communication systems from 1G to 4G have increased demands on the network due to the increased number of devices and increasing volume of data and 5G is expected to significantly increase demands further. Therefore, networks need to be more efficient to deliver the expected increase in volume. An energy and cost efficient way to cope with such an anticipated increase in the demand of voice and data is the dense deployment of small cells i.e. femtocells. Femtocells are identified as a crucial way to the delivery of the increased demands for heterogeneous networks in which macrocells work in combination with femtocells to provide coverage to offices, homes and enterprise. A survey of the literature is conducted to examine the mechanisms and approaches different authors have used to optimise the network. One of the major activities in this project before the transfer was the identification of the parameters. The literature was analysed and key performance parameters were identified. Based on the identified key performance parameters, a simulation framework is used to perform the experiments and to analyse the performance of a two-tier LTE-A system having femtocell overlays. A comprehensive and easy to use graphical user interface has been set up with the desired two- tier network topologies. It estimates the throughput and path loss of all the femto and macro users for all the supported bandwidths of an LTE-A system using different modulation schemes. A series of tests are carried out using the described simulation framework for a range of scenarios. The modulation scheme that yield highest throughput for a femtocell user is identified, and path loss is found to be independent from the modulation scheme but is dependent on the distance from its base station. In another series of experiments, the effects that walls inside buildings have on connectivity are examined and positioning of the femtocells is changed for each scenario inside buildings to analyse the performance. These results are used to find the optimised location of femtocells in different room layouts of the building. The simulation framework is further developed to be able to optimise the whole femtocell network by finding the optimised positioning of femtocells using the genetic optimisation algorithm. The end user can provide the inputs of the desired network topology to the simulation framework through a graphical user interface. The throughput and path loss of all the femto users are calculated before and after optimisation. The simulation results are generated in the form of tables before and after optimisation for comparison and analysis. The layouts depicting the indoor environment of the building before and after optimisation can be seen and analysed through the graphical user interface developed as a part of this simulation framework. Two case studies are defined and described to test the capacity and capability of the developed simulation framework and to show how the simulation framework can be used to identify the optimum positions of the femtocells under different configurations of room designs and number of users that represent contrasting loads on the network. Any desired network topology can be created and analysed on the basis of throughput and path loss by using this simulation framework to optimise the femtocell networks in an indoor environment of the building. The results of the experiments are compared against the claims in other published research

    Growth in Public Interest and Scientific Research on Kinesiology Taping

    Get PDF
    Kinesiology taping has grown in popularity, though there are a number of unsubstantiated claims made by some kinesiology taping advocates. An investigation was conducted into trends in general and scientific interest in kinesiology taping. Data in the public domain (Google Trends and Google Scholar data) indicated significant growth of interest both in terms of public search queries and scientific publications relevant to kinesiology taping. Cyclical trends in interest relevant to kinesiology taping were identified. Segmented regression indicated some of the growth in interest in kinesiology taping may be attributed to exposure of spectators of the Olympic Games to kinesiology taping in athletes. Despite substantial growth in research on kinesiology taping there remain unsubstantiated claims

    Revision workshops in elementary mathematics enhance student performance in routine laboratory calculations

    Get PDF
    The ability to understand and implement calculations required for molarity and dilution computations that are routinely undertaken in the laboratory are essential skills that should be possessed by all students entering an undergraduate Life Sciences degree. However, it is increasingly recognized that the majority of these students are ill equipped to reliably carry out such calculations. There are several factors that conspire against students' understanding of this topic, with the alien concept of the mole in relation to the mass of compounds and the engineering notation required when expressing the relatively small quantities typically involved being two key examples. In this report, we highlight teaching methods delivered via revision workshops to undergraduate Life Sciences students at the University of Nottingham. Workshops were designed to 1) expose student deficiencies in basic numeracy skills and remedy these deficiencies, 2) introduce molarity and dilution calculations and illustrate their workings in a step-by-step manner, and 3) allow students to appreciate the magnitude of numbers. Preworkshop to postworkshop comparisons demonstrated a considerable improvement in students' performance, which attenuated with time. The findings of our study suggest that an ability to carry out laboratory calculations cannot be assumed in students entering Life Sciences degrees in the United Kingdom but that explicit instruction in the form of workshops improves proficiency to a level of competence that allows students to prosper in the laboratory environment

    CONSTITUTIVE MODELLING OF SANDS UNDER MONOTONIC LOADING

    Get PDF
    This paper presents the drained and undrained behavior of soils using a modified version of the original cam clay constitutive model. The strain hardening behavior of soils is one of the major challenges in geotechnical engineering. The constitutive equations are numerically integrated over fixed time steps to apply effective stress to the derived elastoplastic soil model. Convergence of solution is controlled by a constitutive relation, namely the associated flow rule. This study provides step by step Python and octave programs to solve for q"-" p by solving the associated non-linear system. The problem is formulated by assuming small strains in the elastic region and large strains in the plastic region. The transition from over-consolidated to normally consolidated states is predicted to be smooth by this elastoplastic model. The model is recognized and solved as a boundary value problem with only two effective stress variables namely q"-" p which is an approximation of three-dimensional invariants

    Adaptive Filtering on GPS-Aided MEMS-IMU for Optimal Estimation of Ground Vehicle Trajectory

    Get PDF
    Fusion of the Global Positioning System (GPS) and Inertial Navigation System (INS) for navigation of ground vehicles is an extensively researched topic for military and civilian applications. Micro-electro-mechanical-systems-based inertial measurement units (MEMS-IMU) are being widely used in numerous commercial applications due to their low cost; however, they are characterized by relatively poor accuracy when compared with more expensive counterparts. With a sudden boom in research and development of autonomous navigation technology for consumer vehicles, the need to enhance estimation accuracy and reliability has become critical, while aiming to deliver a cost-effective solution. Optimal fusion of commercially available, low-cost MEMS-IMU and the GPS may provide one such solution. Different variants of the Kalman filter have been proposed and implemented for integration of the GPS and the INS. This paper proposes a framework for the fusion of adaptive Kalman filters, based on Sage-Husa and strong tracking filtering algorithms, implemented on MEMS-IMU and the GPS for the case of a ground vehicle. The error models of the inertial sensors have also been implemented to achieve reliable and accurate estimations. Simulations have been carried out on actual navigation data from a test vehicle. Measurements were obtained using commercially available GPS receiver and MEMS-IMU. The solution was shown to enhance navigation accuracy when compared to conventional Kalman filter

    Avascular necrosis of the hip

    No full text
    Avascular necrosis (AVN) of femoral head refers to the death of osteophytes and subsequent structural changes leading to subchondral fracture, femoral head collapse and secondary hip joint osteoarthritis. It is a clinical condition that has been described by various terms including aseptic necrosis, avascular necrosis, osteonecrosis and ischemic necrosis. It was first reported in 1738 by Alexander Munro, a Professor of Anatomy at Edinburgh University. The exact pathophysiology of AVN is still unknown, different mechanisms leading to compromise of the tenuous femoral head blood supply have been suggested but no definitive explanation is fully accepted. This devastating condition often has a delayed presentation in younger patients, limiting management choices. There have been many treatment options detailed. The idea of preserving the femoral head at all costs is losing popularity with the increased proven survivorship in total hip arthroplasty in the younger patient. In this chapter we will discuss the etiology, presumed pathophysiology, classification systems and treatment options for AVN both historic and modern along with their reported success rates.</p

    Gastrointestinal stromal tumor with skeletal muscle, adrenal and cardiac metastases: An unusual occurrence

    No full text
    Gastrointestinal stromal tumor (GIST) is the most common mesenchymal tumor of the bowel. It most commonly arises in the stomach, followed by the small intestine, colorectum and the esophagus. It usually spreads to the liver or the peritoneum, with bone and lung metastases being infrequent. Here, we present a case report of GIST behaving in a bizarre way. The patient presented with skeletal muscle metastasis and was initially misdiagnosed as leiomyosarcoma. On follow-up, he developed adrenal metastasis, and later, cardiac metastasis. None of the above unusual sites has previously been reported in literature to our knowledge
    corecore