Papers by Muhammad Talha Naeem
Mathematics
The paper aims to examine the spillover of uncertainty among commodity markets using Diebold–Yilm... more The paper aims to examine the spillover of uncertainty among commodity markets using Diebold–Yilmaz approach based on forecast error variance decomposition. Next, causal impact of global factors as drivers of uncertainty transmission between oil and other commodity markets is analyzed. Our analysis suggests that oil is a net transmitter to other commodity uncertainties, and this transmission significantly increased during the global financial crisis of 2008–2009. The use of linear and nonlinear causality tests indicates that the global factors have a causal effect on the overall connectedness, and especially on the spillovers from oil to other commodity uncertainties. Further segregation of transmissions between oil to individual commodity markets indicates that stock market implied volatility, risk spread, and economic policy uncertainty are the influential drivers of connectedness among commodity markets.
ABSTRACT In this paper, we consider the uplink communication in a network of cognitive radio node... more ABSTRACT In this paper, we consider the uplink communication in a network of cognitive radio nodes. The transmitting nodes and the receiver are equipped with multiple antennas and MIMO processing abilities. For this network, we study the problem of interference-aware joint secondary user (SU) selection/scheduling and power control (JSUS-QPC). The main objective of the JSUS-QPC is to maximize the sum-rate capacity of the cognitive MIMO uplink communication system under the constraint that the interference to the primary users (PU) is below a specified level. We formulate this optimization problem as nonlinear integer programming problem. The computational complexity of finding an optimal solution to the JSUS-QPC problem by exhaustive search grows exponentially with the number of users and power levels. Therefore, we apply a Quantum Inspired Evolutionary algorithm (QIEA) to determine the suboptimal solution to the JSUS-QPC problem. The proposed scheme has low computational complexity and its results are comparable to the optimal exhaustive search algorithm.
IEEE Radio and Wireless Symposium formerly, 2010
In this paper, we present an algorithm for joint symbol detection (JSD) at the receiver in a Mult... more In this paper, we present an algorithm for joint symbol detection (JSD) at the receiver in a Multi-Device (MD) STBC-MIMO System. We apply Cross Entropy Optimization (CEO) to JSD problem in a MD-STBC-MIMO system. We find that this algorithm has good performance especially at a low SNR region in a rank-deficient MD-STBC-MIMO system. ML detector, Sphere Decoder (SD) and Semi-definite
Journal of Pure and Applied Algebra, 2010
We study the set of Cohen-Macaulay monomial ideals with a given radical. Among this set of ideals... more We study the set of Cohen-Macaulay monomial ideals with a given radical. Among this set of ideals are the so-called Cohen-Macaulay modifications. Not all Cohen-Macaulay squarefree monomial ideals admit nontrivial Cohen-Macaulay modifications. It is shown that if there exists one such modification, then there exist indeed infinitely many.
Journal of Mechanical Science and Technology, 2013
ABSTRACT This study gives a brief work on vibration characteristics of cylindrical shells submerg... more ABSTRACT This study gives a brief work on vibration characteristics of cylindrical shells submerged in an incompressible fluid. The shell is presumed to be structured from functionally graded material. The effect of the fluid is introduced by using the acoustic wave equation. Love’s first order thin shell theory is utilized in the shell dynamical equations. The problem is framed by combining shell dynamical equations with the acoustic wave equation. Fluid-loaded terms are associated with Hankel function of second kind. Wave propagation approach is employed to solve the shell problem. Some comparisons of numerical results are performed for the natural frequencies of simply supported-simply supported, clamped-clamped and clamped-simply supported boundary conditions of isotropic as well as functionally graded cylindrical shells to check the validity of the present approach. The influence of fluid on the submerged functionally graded cylindrical shells is noticed to be very pronounced.
IET Communications, 2013
ABSTRACT In this study, the problem of determining the power allocation that maximises the energy... more ABSTRACT In this study, the problem of determining the power allocation that maximises the energy efficiency of cognitive radio network is investigated as a constrained fractional programming problem. The energy-efficient fractional objective is defined in terms of bits per Joule per Hertz. The proposed constrained fractional programming problem is a non-linear non-convex optimisation problem. The authors first transform the energy-efficient maximisation problem into a parametric optimisation problem and then propose an iterative power allocation algorithm that guarantees ε-optimal solution. A proof of convergence is also given for the ε-optimal algorithm. The proposed ε-optimal algorithm provide a practical solution for power allocation in energy-efficient cognitive radio networks. In simulation results, the effect of different system parameters (interference threshold level, number of primary users and number of secondary users) on the performance of the proposed algorithms are investigated.
Journal of Mechanical Science and Technology, 2010
In this analysis, a comparative study for natural frequencies of two-layered cylindrical shells w... more In this analysis, a comparative study for natural frequencies of two-layered cylindrical shells was presented with one layer composed of functionally graded material and the other layer of isotropic material. Love’s thin shell theory was exploited for the strain-displacement and curvature-displacement relationships. For governing frequency equations, the Rayleigh-Ritz method was utilized to minimize the Lagrangian functional in the form of
Archive of Applied Mechanics, 2011
In the present work, vibration characteristics of thin functionally graded cylindrical shells are... more In the present work, vibration characteristics of thin functionally graded cylindrical shells are studied under the influence of various boundary conditions. Fabrication of FGM cylindrical shell is carried out by using exponential volume fraction law. Strain-and curvature-displacements relationships are taken from Love's thin shell theory. The frequency equation in the form of eigenvalue problem is obtained by adapting the Rayleigh-Ritz method. Characteristic beam functions are assumed to approximate the axial modal dependence. Effects of exponential volume fraction law on the natural frequencies of the FGM cylindrical shells for various boundary conditions are studied against circumferential wave number, length to radius ratio and thickness to radius ratio for different values of power law exponents. Results evaluated show good agreement with those available in the literature. Keywords Cylindrical shells • Functionally graded materials • Exponential volume fraction law • Love's thin shell theory • Rayleigh-Ritz method • Lagrangian functional • Boundary conditions • Natural frequencies Notations A, B, D Extensional, coupling and bending stiffness matrices A
Archive of Applied …
In the present study, a vibration frequency analysis of a bi-layered cylindrical shell composed o... more In the present study, a vibration frequency analysis of a bi-layered cylindrical shell composed of two independent functionally graded layers is presented. The thickness of the shell layers is assumed to be equal and constant. Material properties of the constituents of bi-layered functionally graded cylindrical shell are assumed to vary smoothly and continuously through the thickness of the layers of the shell and are controlled by volume fraction power law distribution. The expressions for strain-displacement and curvature-displacement relationships are utilized from Love's first approximation linear thin shell theory. The versatile Rayleigh-Ritz approach is employed to formulate the frequency equations in the form of eigenvalue problem. Influence of material distribution in the two functionally graded layers of the cylindrical shells is investigated on shell natural frequencies for various shell parameters with simply supported end conditions. To check the validity, accuracy and efficiency of the present methodology, results obtained are compared with those available in the literature.
Applied Mathematics and Mechanics, 2009
In this paper, the influence of an exponential volume fraction law on the vibration frequencies o... more In this paper, the influence of an exponential volume fraction law on the vibration frequencies of thin functionally graded cylindrical shells is studied. Material properties in the shell thickness direction are graded in accordance with the exponential law. Expressions for the strain-displacement and curvature-displacement relationships are taken from Love's thin shell theory. The Rayleigh-Ritz approach is used to derive the shell eigenfrequency equation. Axial modal dependence is assumed in the characteristic beam functions. Natural frequencies of the shells are observed to be dependent on the constituent volume fractions. The results are compared with those available in the literature for the validity of the present methodology.
Aerospace Science and Technology, 2009
Some in-service deterioration in any mechanical device, such as an aero-engine, is inevitable. Al... more Some in-service deterioration in any mechanical device, such as an aero-engine, is inevitable. Also in a country like Pakistan, there is a significant variation of day temperature over the year. As a result of experiencing deterioration (of the engine as a whole or any of its components individually) and/or any alteration in the conditions (such as day temperature) of incoming air stream, an engine will seek a different steady operating point thereby resulting in a variation of the spool speeds and/or turbine-entry temperatures in order to provide the same thrust. Rises in the turbine entry-temperatures and spool speeds result in greater rates of creep and fatigue damage being incurred by the hot-end components and thereby higher engine's life cycle costs. Possessing a better knowledge of the impacts of day temperature variation upon the creep life-consumption of aero-engine's hot-end components, helps the users to take wiser management-decisions. For a military aircraft's mission-profile, using a bespoke computer simulation, the implications of day temperature variation for a turbofan aero-engine's high pressure turbine-blade's creep life-consumption have been predicted.
Advances in Medical Education and Practice, 2013
In an integrated method of education, medical students are introduced to radiology in their precl... more In an integrated method of education, medical students are introduced to radiology in their preclinical years. However, no study has been conducted in Pakistan to demonstrate an academic framework of medical radiology education at an undergraduate level. Therefore, we aimed to document and compare the current level of teaching duties, teaching methodologies, and teaching rewards among radiologists and residents in private and public teaching hospitals in Karachi, Pakistan. Methods: A survey was conducted among 121 radiologists and residents in two private and two public teaching hospitals in Karachi, Pakistan. Radiologists who were nationally registered with the Pakistan Medical and Dental Council either part-time or full-time were included. Radiology residents and fellows who were nationally registered with the Pakistan Medical and Dental Council were also included. Self-administered questionnaires addressing teaching duties, methods, and rewards were collected from 95 participants. Results: The overall response rate was 78.51% (95/121). All of the radiologists were involved in teaching residents and medical students, but only 36% reported formal training in teaching skills. Although most of the respondents (76%) agreed that medical students appeared enthusiastic about learning radiology, the time spent on teaching medical students was less than five hours per week annually (82%). Only 37% of the respondents preferred dedicated clerkships over distributed clerkships (41%). The most common preferred teaching methodology overall was one-on-one interaction. Tutorials, teaching rounds, and problem-based learning sessions were less favored by radiologists than by residents. Teaching via radiology films (86%) was the most frequent mode of instruction. Salary (59%) was the most commonly cited teaching reward. The majority of respondents (88%) were not satisfied with their current level of teaching rewards. Conclusion: All radiologists and residents working in an academic radiology department are involved in teaching undergraduate students at multiple levels. The most valued teaching methodology involves use of images, with one-on-one interaction between the trainer and trainee. The monetary reward for teaching is inbuilt into the salary. The methodology adopted for teaching purposes was significantly different between respondents from private hospitals and those from public teaching hospitals. Because of low satisfaction among the respondents, efforts should be made to provide satisfying teaching rewards.
Journal of Physics: …, 2009
... 107 464 [4] Yang Y, Kayan B, Bozer N, Pate B, Baker C and Gizir AM 2007 J. Chromatogr. ... 44... more ... 107 464 [4] Yang Y, Kayan B, Bozer N, Pate B, Baker C and Gizir AM 2007 J. Chromatogr. ... 44 464 [22] Wang SY, Wu CL, Chu FH, Chien SC, Kuo YH, Shyur LF and Chang ST 2005 Holzforschung 59 295 [23] Surducan E and Surducan V 2008 Procedure and device for dynamic ...
J Pak Med Assoc, 2010
Hypercapneic ARF was defined as the presence of all the following: Respiratory rate higher than 2... more Hypercapneic ARF was defined as the presence of all the following: Respiratory rate higher than 25 breaths/minute, arterial pH less than 7.35, and partial pressure of arterial carbon dioxide (PaCO2) in excess of 45 mmHg. NIV failure was defined as endotracheal intubation and invasive ventilation after placement on NIV and/or death.
Journal of Insect …, 1991
Heliothis zea (Boddie) larvae that fed on an optimal diet (80:20 protein:sugar ratio) had low lev... more Heliothis zea (Boddie) larvae that fed on an optimal diet (80:20 protein:sugar ratio) had low levels of blood trehalose. In contrast, blood trehalose levels were high when larvae fed on a diet with a greater sugar content. Blood trehalose was also elevated in self-selecting larvae that ...
Journal of Software Engineering (JSE), 2008
Improved knowledge management in modern World Wide Web is one of the major and significant issues... more Improved knowledge management in modern World Wide Web is one of the major and significant issues to retrieve accurate and complete data. The hidden Web, also known as the invisible Web or deep Web, has given rise to a new issue of Web mining research. Most documents in the hidden Web, including pages hidden behind search forms, specialized databases, and dynamically generated Web pages, are not accessible by general Web mining application. In this paper a system is designed that has a robust ...
Australian Journal of Basic and Applied Science, 5 (7), 188-193., 2010
ABSTRACT: Increase in the scientific disciplines has caused large data collections as important c... more ABSTRACT: Increase in the scientific disciplines has caused large data collections as important community resources. The volume of interesting data is already measured in terabytes and will soon total in peta-bytes. This research proposal presents the issue of processing massive amount of satellite data. A single LEO satellite sends around 2 GB of data in 24 hours of a day. To process this huge amount of data, normal digital computers face constraints like processing time, recourses and cost. A solution is needed that can ...
ABSTRACT: World Wide Web is enormous compilation of multi-variant data. For better knowledge mana... more ABSTRACT: World Wide Web is enormous compilation of multi-variant data. For better knowledge management it is important to retrieve accurate and complete data. The hidden Web, also known as the invisible Web or deep Web, has given rise to a new issue of Web mining research. Most documents in the hidden Web, including pages hidden behind search forms, specialized databases, and dynamically generated Web pages, are not accessible by general Web mining application. In this paper a system is designed that has a robust ...
Emerging Trends and Applications in Information Communication Technologies, 2012
XMI (XML Metadata Interchange) is used to exchange metadata information of UML (Unified Modeling ... more XMI (XML Metadata Interchange) is used to exchange metadata information of UML (Unified Modeling Language) models using XML (Extensible Markup Language) representation. All major CASE tools eg ArgoUML, Rational Rose, Enterprise Architect, MS Visio, Altova, Smart Draw, etc can export and import XMI. However, current implementation of XMI in all CASE tools does not fulfill the goal of a model interchange as the CASE tools can just import XMI and extract metadata information but cannot generate UML models such as UML class ...
International Conference on Software Engineering (ISE’06) Lahore Pakistan, ISE, 2006
Information or knowledge representation is one of the principal elements of artificial intelligen... more Information or knowledge representation is one of the principal elements of artificial intelligence based applications. Conventionally, predicate logic is used in various languages to represent the required knowledge. The recent fashion in knowledge representation languages is to use XML as the low-level syntax. XML is the standard representation of multi-facet data. This generic representation tends to make the output of these KR languages easy for machines to parse. On the other hand, modern web ...
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Papers by Muhammad Talha Naeem