1,905 research outputs found
Experimental Evaluation of Capacity Statistics for Short VDSL Loops
No full textWe assess the capacity potential of very short very-high data-rate digital subscriber line loops using full-binder channel measurements collected by France Telecom R&D. Key statistics are provided for both uncoordinated and vectored systems employing coordinated transmitters and coordinated receivers. The vectoring benefit is evaluated under the assumption of transmit precompensation for the elimination of self-far-end crosstalk, and echo cancellation of self-near-end crosstalk. The results provide useful bounds for developers and providers alike.©2009 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE. Eleftherios Karipidis, Nicholas Sidiropoulos, Amir Leshem and Li Youming, Experimental Evaluation of Capacity Statistics for Short VDSL Loops, 2005, IEEE Transactions on Communications, (53), 7, 1119-1122.http://dx.doi.org/10.1109/TCOMM.2005.85162
Capacity Statistics for Short DSL Loops from Measured 30 MHz Channel Data
No full textIn recent years, there is growing interest in hybrid fiber-copper access solutions, as in fiber to the basement (FTTB) and fiber to the curb/cabinet (FTTC), combined with advanced vectored transmission modalities. The twisted pair segment in these architectures is in the range of a few hundred meters, thus supporting transmission over up to 30 MHz. In this paper, we assess the capacity potential of these very short loops using full-binder channel measurements collected by France Telecom R&D. Key statistics are provided for both uncoordinated and vectored transmission, and the vectoring benefit is evaluated. The results provide useful bounds for developers and providers alike.©2005 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.Eleftherios Karipidis, Nicholas Sidiropoulos, Amir Leshem and Li Youming, Capacity Statistics for Short DSL Loops from Measured 30 MHz Channel Data, 2005, Proceedings of the 6th IEEE International Workshop on Signal Processing Advances for Wireless Communications (SPAWC), 174-178.http://dx.doi.org/10.1109/SPAWC.2005.150589
SPLATT: Efficient and Parallel Sparse Tensor-Matrix Multiplication
No full textMulti-dimensional arrays, or tensors, are increasingly found in fields such as signal processing and recommender systems. Real-world tensors can be enormous in size and often very sparse. There is a need for efficient, high-performance tools capable of processing the massive sparse tensors of today and the future. This paper introduces SPLATT, a C library with shared-memory parallelism for three-mode tensors. SPLATT contains algorithmic improvements over competing state of the art tools for sparse tensor factorization. SPLATT has a fast, parallel method of multiplying a matricized tensor by a Khatri-Rao product, which is a key kernel in tensor factorization methods. SPLATT uses a novel data structure that exploits the sparsity patterns of tensors. This data structure has a small memory footprint similar to competing methods and allows for the computational improvements featured in our work. We also present a method of finding cache-friendly reorderings and utilizing them with a novel form of cache tiling. To our knowledge, this is the first work to investigate reordering and cache tiling in this context. SPLATT averages almost 30x speedup compared to our baseline when using 16 threads and reaches over 80x speedup on NELL-2.Smith, Shaden; Ravindran, Niranjay; Sidiropoulos, Nicholas D.; Karypis, George. (2015). SPLATT: Efficient and Parallel Sparse Tensor-Matrix Multiplication. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/215973
Joint QoS Multicast Power / Admission Control and Base Station Assignment : A Geometric Programming Approach
No full textThe joint power control and base station (BS) assignment problem is considered under Quality-of-Service (QoS) constraints. If a feasible solution exists, the problem can be efficiently solved using existing distributed algorithms. Infeasibility is often encountered in practice, however, which brings up the issue of optimal admission control. The joint problem is NP-hard, yet important for QoS provisioning and bandwidth-efficient operation of existing and emerging cellular and overlay/underlay networks. Recognizing this, there have been several attempts to develop reasonable heuristics for joint admission and power control. This contribution takes a more disciplined approach. The joint problem is first concisely formulated as a constrained optimization problem, whose objective combines the BS assignment, admission, and power control components. The formulation also allows for multicasting. A geometric programming approximation is then developed, which forms the core of a heuristic, yet well-motivated centralized algorithm that generates approximate solutions to the original NP-hard problem. Numerical results against an enumeration baseline illustrate the merits of the approach.©2008 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.Eleftherios Karipidis, Nicholas Sidiropoulos and Leandros Tassiulas, Joint QoS Multicast Power / Admission Control and Base Station Assignment: A Geometric Programming Approach, 2008, Proceedings of the 5th IEEE Workshop on Sensor Array and Multi-Channel Signal Processing (SAM), 155-159.http://dx.doi.org/10.1109/SAM.2008.460684
Kruskal’s permutation lemma and the identification of CANDECOMP/PARAFAC and bilinear models with constant modulus constraints
No full textCANDECOMP/PARAFAC (CP) analysis is an extension of low-rank matrix decomposition to higher-way arrays, which are also referred to as tensors. CP extends and unifies several array signal processing tools and has found applications ranging from multidimensional harmonic retrieval and angle-carrier estimation to blind multiuser detection. The uniqueness of CP decomposition is not fully understood yet, despite its theoretical and practical significance. Toward this end, we first revisit Kruskal's permutation lemma, which is a cornerstone result in the area, using an accessible basic linear algebra and induction approach. The new proof highlights the nature and limits of the identification process. We then derive two equivalent necessary and sufficient uniqueness conditions for the case where one of the component matrices involved in the decomposition is full column rank. These new conditions explain a curious example provided recently in a previous paper by Sidiropoulos, who showed that Kruskal's condition is in general sufficient but not necessary for uniqueness and that uniqueness depends on the particular joint pattern of zeros in the (possibly pretransformed) component matrices. As another interesting application of the permutation lemma, we derive a similar necessary and sufficient condition for unique bilinear factorization under constant modulus (CM) constraints, thus providing an interesting link to (and unification with) CP.</p
Characterization and structure in the development of Tudor comedy
No full textThe role of characterization in dramatic structure is assessed by theoretical criteria.
Characters who perform actions necessary for the completion of the narrative sequence are
said to be "bound" to the narrative; those without such obligations are "free". Characters
who maintain a single, constant meaning during the course of a play are said to be "static";
characters who change or develop into new roles are "dynamic". Horatian decorum
demanded that comic characters be static, and the characters of Plautine and Terentian
tradition were almost always bound to narrative intrigue. However, evaluations of six
Tudor comedies show an increasing use of non-classical characterization within the comic
form.
In the early comedies lohan lohan and Roister Doister all characters are bound and
static, yet the impetus to enlarge the role of characterization is evident. The characters of
lohan lohan are expanded from their French source, and Roister Doister includes
extraneous episodes in which Udall displays his braggart hero. Free characters abound in
Misogonus; as well the play brings dynamic characterization into the scope of comedy with
the conversion of its prodigal son.
Free characters offer new possibilities of non-narrative plotting. In comedies of the
1580s favourite traditional characters appear as diversions outside the action, and thematic
arrangements of characters inform the increasingly complex plots. Lyly stresses the
symbolic potential of characters in Endimion, whereas Greene uses dynamic
characterization to heighten the illusion of independent figures in Friar Bacon and Friar
Bungay. Love's Labour's Lost exposes the limitations of comic artifice by pulling the
characters between convention and individualization.
By the end of the sixteenth century free and dynamic characters had become
common, and characterization had established a sizable claim on the design of English
comedy. These developments set the English form apart from its neoclassical counterparts
Chapter 10 - Introduction to Radar Signal Processing
No full textSignal processing for radar systems is a vast and fascinating discipline that concerns many different
techniques and fields of application. The complete Elsevier Reference includes this section along with
that on Array Signal Processing, which is intimately related to radar techniques. This section focuses
on the most recent and exciting findings on the applications of signal processing techniques in radar
systems, described in a tutorial manner, such that newcomers in the area can learn what is going on in
this always in progress field of research. The basics and the new findings on array signal processing
techniques are covered in the Array Signal Processing section edited by Mats Viberg.
The history of radar started more than one hundred years ago, in 1904, when Christian Hülsmeyer
demonstrated the first experimental radar in Cologne, Germany. Later, in 1920, Guglielmo Marconi also
observed the radio detection of targets in his experiments, but it was not until World War II that dynamic
development of radar began. It has since then evolved into an indispensable all-weather, long-range
sensor. Military and security applications have always been the main drivers of radar developments.
However, later on radar has become a key sensor for civil applications including air, maritime, and
ground traffic control and the guidance of aircraft and vehicles on airport surfaces.
According to its acronym RAdio Detection And Ranging, the classical radar mission is to detect and
locate objects. With the advent of coherent pulse radar, velocity measurements have become possible by
exploitingtheDopplereffect.Todayspecializedradarsmeasureelevation,aidinweathermonitoring,and
help with target classification. To find an overview of basic radar concepts and radar signal processing
algorithms the interested reader can refer to [1
External interventions and the duration of civil wars
No full textThe authors combine an empirical model of external intervention, with a theoretical model of civil war duration. Their empirical model of intervention allows them to analyze civil war duration, using"expected"rather than"actual"external intervention as an explanatory variable in the duration model. Unlike previous studies, they find that external intervention is positively associated with the duration of civil war. They distinguish partial third-party interventions that extend the length of war, from multilateral"peace"operations, which have a mandate to restore peace without taking sides - and which typically take place at war's end, or at least when both sides have agreed to a cease-fire. In a future paper, the authors will examine whether partial third-party interventions - whatever their effect on a war's duration - increase the risk of war's recurrence. If that proves true, then even if interventions reduce the length of civil war, they may do so at the cost of further destabilizing the political system, and sowing the seeds of future rebellion.Children and Youth,Peace&Peacekeeping,Post Conflict Reconstruction,Post Conflict Reconstruction,International Affairs,Post Conflict Reconstruction,Social Conflict and Violence,Peace&Peacekeeping,Post Conflict Reconstruction,International Affairs
An Influential Collector : Tsar Nicholas I of Russia
No full textTsar Nicholas I of Russia (1796-1855) was one of the European sovereigns most firmly committed to guaranteeing the principle of monarchy following the Congress of Vienna. The importance of his political role has, however, overshadowed his role as a collector, patron and promoter of the arts. This article analyzes his artistic education, his tastes and aesthetic orientation and the works he bought for his personal art collection and for the ‘New Hermitage’ museum, which he inaugurated in 1852. By observing various instances in which he influenced the Russian artists of the time and the formation of the Museum’s collections, the author shows how the Tsar promoted not only monarchic principles, but also precise monarchic taste and artistic criteria
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