84 research outputs found

    Real-Time Implementation of Spectrum Sensing Techniques in Cognitive Radios

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    Wireless communication requirements of higher sampling frequencies and bandwidth are ever increasing. For this purpose, exploitation of underutilized spectrum bands was one the challenging research targets. Cognitive Radio (CR) is a promising solution to overcome the ‚Äúlimited bandwidth‚ÄĚ issue. Software defined radio (SDR) is the enabler of CR. The aim of the thesis is to adopt the vacant TV channels for secondary users. Spectrum sensing prototype has been proposed to detect TV white space (TVWS). The prototype has been developed using Universal Software Radio Peripheral (USRP) and examined to sense TVWS in the real time world. The conducting analysis of obtained measurements showed the state of unoccupied spectrum bands in the UHF band ranges from 500 MHz to 698 MHz in the urban area ofWindsor, Ontario, Canada. Two different spectrum sensing techniques namely, the energy detector, and pilot-tone detector were employed to get the result with minimum computational complexity. Experiments show that the presence of incumbent users can be easily detected using the spectrum sensing techniques mentioned in the thesis. The experimental results have demonstrated the validity of the proposed prototyp

    Impact of Charge on Traversable Wormhole Solutions in f(R,T)f(R,T) Theory

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    This paper examines the effects of charge on traversable wormhole structure in f(R,T)f(R,T) theory. For this purpose, we use the embedding class-I approach to build a wormhole shape function from the static spherically symmetric spacetime. The developed shape function satisfies all the required conditions and connects two asymptotically flat regions of spacetime. We consider different models of this modified theory to examine the traversable wormhole solutions through null energy condition and also check their stable state. We conclude that viable and stable wormhole solutions are obtained under the influence of charge in this gravitational theory.Comment: 21 pages, 5 figure

    An adaptive discrete Newton method for regularization-free Bingham model

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    [EN] Developing a numerical and algorithmic tool which correctly identifies unyielded regions in yield stress fluid flow is a challenging task. Two approaches are commonly used to handle the singular behaviour at the yield surface, i.e. the Augmented Lagrangian approach and the regularization approach, respectively. Generally in the regularization approach, solvers do not perform efficiently when the regularization parameter gets very small. In this work, we use a formulation introducing a new auxiliary stress. The three field formulation of the yield stress fluid corresponds to a regularization-free Bingham formulation. The resulting set of equations arising from the three field formulation is solved efficiently and accurately by a monolithic finite element method. The velocity and pressure are discretized by the higher order stable FEM pair Q2/Pdisc 1 and the auxiliary stress is discretized by the Q2 element. Furthermore, this problem is highly nonlinear and presents a big challenge to any nonlinear solver. Therefore, we developed a new adaptive discrete Newton method, which evaluates the Jacobian with the divided difference approach. We relate the step length to the rate of the actual nonlinear reduction for achieving a robust adaptive Newton method. We analyse the solvability of the problem along with the adaptive Newton method for Bingham fluids by doing numerical studies for a prototypical configuration ‚ÄĚviscoplastic fluid flow in a channel‚ÄĚ.We would like to thank the Deutsche Forschungsgemeinschaft (DFG) for their financial support under the DFG Priority Program SPP 1962. The authors also acknowledge the support by LS3 and LiDO3 team at ITMC, TU Dortmund UniversityFatima, A.; Turek, S.; Ouazzi, A.; Afaq, MA. (2022). An adaptive discrete Newton method for regularization-free Bingham model. En Proceedings of the YIC 2021 - VI ECCOMAS Young Investigators Conference. Editorial Universitat Polit√®cnica de Val√®ncia. 180-189. https://doi.org/10.4995/YIC2021.2021.12389OCS18018

    Monolithic Newton-Multigrid Solver for Multiphase Flow Problems with Surface Tension

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    [EN] We have developed a monolithic Newton-multigrid solver for multiphase flow problems which solves velocity, pressure and interface position simultaneously. The main idea of our work is based on the formulations discussed in [1], where it points out the feasibility of a fully implicit monolithic solver for multiphase flow problems via two formulations, a curvature-free level set approach and a curvature-free cutoff material function approach. Both formulations are fully implicit and have the advantages of requiring less regularity, since neither normals nor curvature are explicitly calculated, and no capillary time restriction. Furthermore, standard Navier-Stokes solvers might be used, which do not have to take into account inhomogeneous force terms. The reinitialization issue is integrated with a nonlinear terms within the formulations.The nonlinearity is treated with a Newton-type solver with divided difference evaluation of the Jacobian matrices. The resulting linearized system inside of the outer Newton solver is a typical saddle point problem which is solved using the geometrical multigrid with Vanka-like smoother using higher order stable FEM pair Q2/P1discQ_2/P^{\text{disc}}_1 for velocity and pressure and Q2Q_2 for all other variables. The method is implemented into an existing software packages for the numerical simulation of multiphase flows (FeatFlow). The robustness and accuracy of this solver is tested for two different test cases, i.e. static bubble and oscillating bubble, respectively [2].Muhammad Aaqib Afaq would like to thank Erasmus Mundus INTACT project, funded by the European Union as part of the Erasmus Mundus programme and the National University of Sciences and Technology (NUST) for their financial support. The authors also acknowledge the support by LS3 and LiDO3 team at ITMC, TU Dortmund University.Afaq, MA.; Turek, S.; Ouazzi, A.; Fatima, A. (2022). Monolithic Newton-Multigrid Solver for Multiphase Flow Problems with Surface Tension. En Proceedings of the YIC 2021 - VI ECCOMAS Young Investigators Conference. Editorial Universitat Politècnica de València. 190-199. https://doi.org/10.4995/YIC2021.2021.12390OCS19019

    Hirayama disease, a rare cause of posture related cord compression: a case report from radiological perspective

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    Hirayama Disease is a disease of young adults lying in the age group between twenty to thirty years. It is an extremely uncommon disorder. Its other synonyms are juvenile muscular atrophy of the distal upper extremity (JMADUE) or monomelic amyotrophy (MMA). A previously healthy 25-year-old man presented with gradually increasing weakness in both hands for the past few years. There was neither history of trauma nor family history of neuromuscular disease. MRI was advised. Routine cervical sagittal MR images (Non-flexion or extension) revealed cord flattening and atrophy at C5 to C7 levels.There was evidence of syrinx. Flexion MRI was performed later on. Midline sagittal T1- and T2-weighted images of the cervical spine showed anterior displacement of the cervical cord with marked flattening of cord. The patient was advised to modify his posture, avoid flexion and to apply cervical collar. Physiotherapy was started to improve the tone of muscles. In case of deterioration of symptoms he was advised to consult for surgery. The purpose of this case report is to show the importance of dynamic scan in symptomatic patients especially in their second or third decade with progressive upper limb weakness. Mostly the scanning in neutral posture does not reveal any significant cord compression. Similarly a normal looking thecal sac with preserved anterior and posterior thecal sleeves without disc disease dramatically changes on change of posture. This case shows the importance of dynamic scanning in symptomatic patients with progressive upper limb weakness and with no obvious cause of the cord changes on routine MR images. Cervical collar, physiotherapy and in resistant cases surgery is recommended for management

    Assessing the Role of Mobile Banking Applications in Creating Brand Loyalty among the Consumers of Commercial Banks

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    The Internet is transforming the world and abruptly revolutionizing every field of life. Due to rampant advancement in internet technologies, the world is getting shrunk into the pocket and the concept of distances has been evoked. Advancement in the internet has given birth to many other distinguished technologies such as artificial intelligence, the internet of things, and metaverse, and these inventions have revolutionized the whole technological scenario In this modern era and especially after the pandemic COVID-19 world has shifted to smart technologies and the use of mobile banking applications has been boosted, Mobile Banking Applications are like a virtual bank where customers can experience the quality of banking services through the interface of applications. In this current research, we will try to root out how mobile applications create brand loyalty among the consumers of commercial banks in Bahawalpur. Key Words: Mobile Banking, Brand Loyalty, Artificial Intelligence, Commercial Banks, Loyalty Schemes, Financial Application

    Association of Stress, Knowledge Management, and Change with Organizational Effectiveness in Education Sector of Pakistan

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    The purpose of this study is to analyze the impact of organizational stress, knowledge management, and organizational change on organizational effectiveness. A valid questionnaire was distributed to administrative staff and faculty members of different educational institutes. 100 questionnaires were distributed in public and private educational sectors. 75 complete questionnaires were received at response rate of 75%. A non probability random sampling technique was used to select the sample. Pearson’s moment correlation and linear regression was applied to study the relationship between organizational stress, knowledge management, organizational change and organizational effectiveness. Results show significant relationship of factors and positive impact on organizational effectiveness. This research also discusses practical implicatios and research limitations.&nbsp
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