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Shahid N.,LUMS | Naqvi I.H.,LUMS
2011 7th International Conference on Emerging Technologies, ICET 2011 | Year: 2011

Support vector machines (SVM) have formulated the main concepts of machine learning, ever since their introduction. The one-class quarter sphere SVM has received recent interest, as it extends the concepts of machine learning to the domain of linear optimization problems with cost efficiency. This paper deals with the novel idea of a quarter-sphere SVM based only on temporal-attribute correlations. To avoid communication overhead the system complexity at individual sensor nodes is slightly increased. The outlier and event detection rate keeps up with the detection rate obtained via previous approaches with an added advantage of no communication cost. © 2011 IEEE.

Nadeem U.,LUMS | Hassan N.U.,LUMS | Pasha M.A.,LUMS | Yuen C.,Singapore University of Technology and Design
Electronics Letters | Year: 2014

A wireless indoor positioning system using white LED lights is proposed. The time difference of arrival technique is employed and the phase differences between the received signals are determined to develop a positioning algorithm which can estimate the receiver location with a mean localisation error as low as 1 mm in a room of dimensions 5 × 5 × 3 m. Through simulations, it is identified that the optimum receiver height where localisation error gets minimised is between 2.5 and 3 m from the ceiling which corresponds well with the typical dimensions of a room. © The Institution of Engineering and Technology 2014.

Mahmood A.,University of Punjab | Khan S.,LUMS
IEEE Transactions on Image Processing | Year: 2010

Elimination Algorithms are often used in template matching to provide a significant speed-up by skipping portions of the computation while guaranteeing the same best-match location as exhaustive search. In this work, we develop elimination algorithms for correlation-based match measures by exploiting the transitivity of correlation. We show that transitive bounds can result in a high computational speed-up if strong autocorrelation is present in the dataset. Generally strong intrareference local autocorrelation is found in natural images, strong inter-reference autocorrelation is found if objects are to be tracked across consecutive video frames and strong intertemplate autocorrelation is found if consecutive video frames are to be matched with a reference image. For each of these cases, the transitive bounds can be adapted to result in an efficient elimination algorithm. The proposed elimination algorithms are exact, that is, they guarantee to yield the same peak location as exhaustive search over the entire solution space. While the speed-up obtained is data dependent, we show empirical results of up to an order of magnitude faster computation as compared to the currently used efficient algorithms on a variety of datasets. © 2006 IEEE.

Nadeem U.,LUMS | Hassan N.U.,LUMS | Pasha M.A.,LUMS | Yuen C.,Singapore University of Technology and Design
Electronics Letters | Year: 2015

The performance of time division multiplexing and frequency division multiplexing protocols for light emitting diode light emitting diode (IPS) designs using visible light emitting diode lights is evaluated. The impact of timing synchronisation errors on the localisation accuracy of IPS designs is also determined. © The Institution of Engineering and Technology 2015.

Mustafa N.H.,LUMS | Ray S.,Max Planck Institute for Informatics
Discrete and Computational Geometry | Year: 2010

We consider the problem of computing minimum geometric hitting sets in which, given a set of geometric objects and a set of points, the goal is to compute the smallest subset of points that hit all geometric objects. The problem is known to be strongly NP-hard even for simple geometric objects like unit disks in the plane. Therefore, unless P = NP, it is not possible to get Fully Polynomial Time Approximation Algorithms (FPTAS) for such problems. We give the first PTAS for this problem when the geometric objects are half-spaces in ℝ 3 and when they are an r-admissible set regions in the plane (this includes pseudo-disks as they are 2-admissible). Quite surprisingly, our algorithm is a very simple local-search algorithm which iterates over local improvements only. © 2010 Springer Science+Business Media, LLC.

Munir A.,LUMS | Qazi I.A.,LUMS | Uzmi Z.A.,LUMS | Mushtaq A.,LUMS | And 3 more authors.
Proceedings - IEEE INFOCOM | Year: 2013

For provisioning large-scale online applications such as web search, social networks and advertisement systems, data centers face extreme challenges in providing low latency for short flows (that result from end-user actions) and high throughput for background flows (that are needed to maintain data consistency and structure across massively distributed systems). We propose L2DCT, a practical data center transport protocol that targets a reduction in flow completion times for short flows by approximating the Least Attained Service (LAS) scheduling discipline, without requiring any changes in application software or router hardware, and without adversely affecting the long flows. L2DCT can co-exist with TCP and works by adapting flow rates to the extent of network congestion inferred via Explicit Congestion Notification (ECN) marking, a feature widely supported by the installed router base. Though L2DCT is deadline unaware, our results indicate that, for typical data center traffic patterns and deadlines and over a wide range of traffic load, its deadline miss rate is consistently smaller compared to existing deadline-driven data center transport protocols. L2DCT reduces the mean flow completion time by up to 50% over DCTCP and by up to 95% over TCP. In addition, it reduces the completion for 99th percentile flows by 37% over DCTCP. We present the design and analysis of L2DCT, evaluate its performance, and discuss an implementation built upon standard Linux protocol stack. © 2013 IEEE.

Hussain N.,King Abdulaziz University | Shah M.H.,LUMS
Computers and Mathematics with Applications | Year: 2011

In this paper we establish some topological properties of the cone b-metric spaces and then improve some recent results about KKM mappings in the setting of a cone b-metric space. We also prove some fixed point existence results for multivalued mappings defined on such spaces. © 2011 Elsevier Ltd. All rights reserved.

Basit A.,LUMS | Mustafa N.H.,LUMS | Ray S.,Ecole Polytechnique Federale de Lausanne | Raza S.,LUMS
Discrete and Computational Geometry | Year: 2010

The so-called first selection lemma states the following: given any set P of n points in ℝd, there exists a point in ℝd contained in at least cdnd+1-O(nd) simplices spanned by P, where the constant cd depends on d. We present improved bounds on the first selection lemma in ℝ3. In particular, we prove that c3≥0. 00227, improving the previous best result of c3≥0. 00162 by Wagner (On k-sets and applications. Ph. D. thesis, ETH Zurich, 2003). This makes progress, for the three-dimensional case, on the open problems of Bukh et al. (Stabbing simplices by points and flats. Discrete Comput. Geom., 2010) (where it is proven that c3≤1/44≈0. 00390) and Boros and Füredi (The number of triangles covering the center of an n-set. Geom. Dedic. 17(1):69-77, 1984) (where the two-dimensional case was settled). © 2010 Springer Science+Business Media, LLC.

Zaheer A.,LUMS | Akhter I.,LUMS | Haris Baig M.,LUMS | Marzban S.,LUMS | Khan S.,LUMS
Proceedings of the IEEE International Conference on Computer Vision | Year: 2011

Most nonrigid objects exhibit temporal regularities in their deformations. Recently it was proposed that these regularities can be parameterized by assuming that the nonrigid structure lies in a small dimensional trajectory space. In this paper, we propose a factorization approach for 3D reconstruction from multiple static cameras under the compact trajectory subspace representation. Proposed factorization is analogous to rank-3 factorization of rigid structure from motion problem, in transformed space. The benefit of our approach is that the 3D trajectory basis can be directly learned from the image observations. This also allows us to impute missing observations and denoise tracking errors without explicit estimation of the 3D structure. In contrast to standard triangulation based methods which require points to be visible in at least two cameras, our approach can reconstruct points, which remain occluded even in all the cameras for quite a long time. This makes our solution especially suitable for occlusion handling in motion capture systems. We demonstrate robustness of our method on challenging real and synthetic scenarios. © 2011 IEEE.

Brkic Z.,Erasmus University Rotterdam | Maria N.I.,Erasmus University Rotterdam | Van Helden-Meeuwsen C.G.,Erasmus University Rotterdam | Van De Merwe J.P.,Erasmus University Rotterdam | And 6 more authors.
Annals of the Rheumatic Diseases | Year: 2013

Objective To determine the prevalence of upregulation of interferon (IFN) type I inducible genes, the so called "IFN type I signature", in CD14 monocytes in 69 patients with primary Sjögren's syndrome (pSS) and 44 healthy controls (HC) and correlate it with disease manifestations and expression of B cell activating factor (BAFF). Methods Expression of IFI44L, IFI44, IFIT3, LY6E and MX1 was measured using real time quantitative PCR in monocytes. Expression values were used to calculate IFN type I scores for each subject. pSS patients positive for the IFN type I signature (IFN score≥10) and patients negative for the signature (IFN score<10) were then compared for clinical disease manifestations and BAFF expression. A bioassay using a monocytic cell line was performed to study whether BAFF mRNA expression was inducible by IFN type I activity in serum of patients with pSS. Results An IFN type I signature was present in 55% of patients with pSS compared with 4.5% of HC. Patients with the IFN type I signature showed: (a) higher EULAR Sjögren's Syndrome Disease Activity Index scores; higher anti-Ro52, anti-Ro60 and anti-La autoantibodies; higher rheumatoid factor; higher serum IgG; lower C3, lower absolute lymphocyte and neutrophil counts; (b)higher BAFF gene expression in monocytes. In addition, serum of signature-positive patients induced BAFF gene expression in monocytes. Conclusions The monocyte IFN type I signature identifies a subgroup of patients with pSS with a higher clinical disease activity together with higher BAFF mRNA expression. Such patients might benefit from treatment blocking IFN type I production or activity.

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