bluuebunny/crossref_metadata_2025 huggingface dataset:
Modeling of the Effective Elastic Properties of Multifunctional Carbon Nanocomposites Due to Agglomeration of Straight Circular Carbon Nanotubes in a Polymer Matrix
Authors: Jarali Chetan Shivaputra , Basavaraddi Somaraddi R. , Kiefer Björn , Pilli Sharanabasava C. , Charles Lu Y.
Published: July 2013

In the present study, the effective elastic properties of multifunctional carbon nanotube composites are derived due to the agglomeration of straight circular carbon nanotubes dispersed in soft polymer matrices. The agglomeration of CNTs is common due to the size of nanotubes, which is at nanoscales. Furthermore, it has been proved that straight circular CNTs provide higher stiffness and elastic properties than any other shape of the nanofibers. Therefore, in the present study, the agglomeration effect on the effective elastic moduli of the CNT polymer nanocomposites is investigated when circular CNTs are aligned straight as well as distributed randomly in the matrix. The Mori–Tanaka micromechanics theory is adopted to newly derive the expressions for the effective elastic moduli of the CNT composites including the effect of agglomeration. In this direction, analytical expressions are developed to establish the volume fraction relationships for the agglomeration regions with high, and dilute CNT concentrations. The volume of the matrix in which there may not be any CNTs due to agglomeration is also included in the present formulation. The agglomeration volume fractions are subsequently adopted to develop the effective relations of the composites for transverse isotropy and isotropic straight CNTs. The validation of the modeling technique is assessed with results reported, and the variations in the effective properties for high and dilute agglomeration concentrations are investigated.
Thermoelastodynamics in Transversely Isotropic Media With Scalar Potential Functions1
Authors: Eskandari-Ghadi Morteza , Rahimian Mohammad , Sture Stein , Forati Maysam
Published: July 2013

A complete set of potential functions consisting of three scalar functions is presented for coupled displacement-temperature equations of motion and heat equation for an arbitrary x3-convex domain containing a linear thermoelastic transversely isotropic material, where the x3-axis is parallel to the axis of symmetry of the material. The proof of the completeness theorem is based on a retarded logarithmic potential function, retarded Newtonian potential function, repeated wave equation, the extended Boggio's theorem for the transversely isotropic axially convex domain, and the existence of a solution for the heat equation. It is shown that the solution degenerates to a set of complete potential functions for elastodynamics and elastostatics under certain conditions. In a special case, the number of potential functions is reduced to one, and the required conditions are discussed. Another special case involves the rotationally symmetric configuration with respect to the axis of symmetry of the material.
Overtrawlability and Mechanical Damage of Pipe-in-Pipe
Authors: Jiexin Zheng , Palmer Andrew , Brunning Paul
Published: July 2013

A pipeline on the seabed may be struck by moving trawl gear, and that may damage the pipeline. Trenching can be a useful but expensive way to protect the pipeline. Pipe-in-pipe and bundled pipeline systems are widely used in the offshore industry recently because of their high level of thermal insulation and because they lend themselves to rapid and economical installation. However, there is no clearly specified standard method to analyze the overtrawlability of pipe-in-pipe systems. If we apply the same method as for the single wall pipe, it is likely to result in a conservative design for the pipe-in-pipe. The objective of this paper is to investigate the overtrawlability of pipe-in-pipe, especially in the impact phase, and to fill this gap. In this study, the authors demonstrate that a quasi-static analysis can replace a dynamic analysis to some extent because the overall response does not show a big difference. The demonstration is based on both quasi-static indentation tests and impact tests for single wall pipe and pipe-in-pipe, as well as the corresponding finite element (FE) models. The FE models not only help to compare the responses but also offer a way to analyze the overtrawlability of the pipe-in-pipe. The quasi-static FE models are used for a further comparison between a pipe-in-pipe and a 406.4 mm (16 in.) single wall pipe to illustrate the overtrawlability of the pipe-in-pipe.
Gray matter parcellation constrained full brain fiber bundling with diffusion tensor imaging
Authors: Xu Qing , Anderson Adam W. , Gore John C. , Ding Zhaohua
Published: July 2013

Purpose:

Studying white matter fibers from diffusion tensor imaging (DTI) often requires them to be grouped into bundles that correspond to coherent anatomic structures, particularly bundles that connect cortical/subcortical basic units. However, traditional fiber clustering algorithms usually generate bundles with poor anatomic correspondence as they do not incorporate brain anatomic information into the clustering process. On the other hand, image registration‐based bundling methods segment fiber bundles by referring to a coregistered atlas or template with prelabeled anatomic information, but these approaches suffer from the uncertainties introduced from misregistration and fiber tracking errors and thus the resulting bundles usually have poor coherence. In this work, a bundling algorithm is proposed to overcome the above issues.

Methods:

The proposed algorithm combines clustering‐ and registration‐based approaches so that the bundle coherence and the consistency with brain anatomy are simultaneously achieved. Moreover, based on this framework, a groupwise fiber bundling method is further proposed to leverage a group of DTI data for reducing the effect of the uncertainties in a single DTI data set and improving cross‐subject bundle consistency.

Results:

Using the Montreal Neurological Institute template, the proposed methods are applied to building a full brain bundle network that connects cortical/subcortical basic units. Based on several proposed metrics, the resulting bundles show promising bundle coherence and anatomic consistency as well as improved cross‐subject consistency for the groupwise bundling.

Conclusions:

A fiber bundling algorithm has been proposed in this paper to cluster a set of whole brain fibers into coherent bundles that are consistent to the brain anatomy.
Determination of air‐kerma strength for the 192Ir GammaMed iX pulsed‐dose‐rate brachytherapy source
Authors: Riley A. D. , Pike T. L. , Micka J. A. , Fulkerson R. K. , DeWerd L. A.
Published: July 2013

Purpose:

Pulsed‐dose‐rate (PDR) brachytherapy was originally proposed to combine the therapeutic advantages of high‐dose‐rate (HDR) and low‐dose‐rate brachytherapy. Though uncommon in the United States, several facilities employ pulsed‐dose‐rate brachytherapy in Europe and Canada. Currently, there is no air‐kerma strength standard for PDR brachytherapy 192Ir sources traceable to the National Institute of Standards and Technology. Discrepancies in clinical measurements of the air‐kerma strength of the PDR brachytherapy sources using HDR source‐calibrated well chambers warrant further investigation.

Methods:

In this research, the air‐kerma strength for an192Ir PDR brachytherapy source was compared with the University of Wisconsin Accredited Dosimetry Calibration Laboratory transfer standard well chambers, the seven‐distance technique [B. E. Rasmussen et al., “The air‐kerma strength standard for 192Ir HDR sources,” Med. Phys. 38, – (2011)] 10.1118/1.3656683, and the manufacturer's stated value. Radiochromic film and Monte Carlo techniques were also employed for comparison to the results of the measurements.

Results:

While the measurements using the seven‐distance technique were within + 0.44% from the manufacturer's determination, there was a + 3.10% difference between the transfer standard well chamber measurements and the manufacturer's stated value. Results showed that the PDR brachytherapy source has geometric and thus radiological qualities that exhibit behaviors similar to a point source model in contrast to a conventional line source model.

Conclusions:

The resulting effect of the pointlike characteristics of the PDR brachytherapy source likely account for the differences observed between well chamber and in‐air measurements.
Calculation method using Clarkson integration for the physical dose at the center of the spread‐out Bragg peak in carbon‐ion radiotherapy
Authors: Tajiri Minoru , Maeda Takamasa , Koba Yusuke , Isobe Yoshiharu , Kuroiwa Toshitaka , Fukuda Shigekazu , Tanimoto Katsuyuki , Shibayama Koichi
Published: July 2013

Purpose:

In broad‐beam carbon‐ion radiotherapy performed using the heavy‐ion medical accelerator in Chiba, the number of monitor units is determined by measuring the physical dose at the center of the spread‐out Bragg peak (SOBP) for the treatment beam. The total measurement time increases as the number of treatment beams increases, which hinders the treatment of an increased number of patients. Hence, Kusano et al. [Jpn. J. Med. Phys. 23(Suppl. 2), – (2003)] proposed a method to calculate the physical dose at the center of the SOBP for a treatment beam. Based on a recent study, the authors here propose a more accurate calculation method.

Methods:

The authors measured the physical dose at the center of the SOBP while varying the circular field size and range‐shifter thickness. The authors obtained the physical dose at the center of the SOBP for an irregularly shaped beam using Clarkson integration based on these measurements.

Results:

The difference between the calculated and measured physical doses at the center of the SOBP varied with a change in the central angle of the sector segment. The differences between the calculated and measured physical doses at the center of the SOBP were within ±1% for all irregularly shaped beams that were used to validate the calculation method.

Conclusions:

The accuracy of the proposed method depends on both the number of angular intervals used for Clarkson integration and the fineness of the basic data used for calculations: sampling numbers for the field size and thickness of the range shifter. If those parameters are properly chosen, the authors can obtain a calculated monitor unit number with high accuracy sufficient for clinical applications.
A COMPARED ANALYSIS OF THE SUSCEPTIBILITY IN THE O(N) THEORY
Authors: BRANCHINA VINCENZO , MESSINA EMANUELE , ZAPPALÀ DARIO
Published: July 2013

The longitudinal susceptibility χL of the O(N) theory in the broken phase is analyzed by means of three different approaches, namely the leading contribution of the 1/N expansion, the Functional Renormalization Group flow in the Local Potential approximation and the improved effective potential via the Callan–Symanzik equations, properly extended to d = 4 dimensions through the expansion in powers of ϵ = 4-d. The findings of the three approaches are compared and their agreement in the large N limit is shown. The numerical analysis of the Functional Renormalization Group flow equations at small N supports the vanishing of [Formula: see text] in d = 3 and d = 3.5 but is not conclusive in d = 4, where we have to resort to the Callan–Smanzik approach. At finite N as well as in the limit N→∞, we find that [Formula: see text] vanishes with J as Jϵ/2 for ϵ> 0 and as ( ln (J))-1 in d = 4.
SIZE DISTRIBUTION OF GENE FAMILIES IN A GENOME
Authors: RUDNICKI RYSZARD , TIURYN JERZY
Published: July 2013

We consider a probabilistic model of genome evolution. We are interested in size distribution of gene families. The model is based on three fundamental evolutionary events: gene loss, duplication and accumulated change. We assume that the probability of gene loss and duplication is constant and the probability of gene mutation mi depends on the size i of a family. We prove that size distribution of paralogous gene families in a genome converges to the equilibrium as time goes to infinity. Moreover, we show how this equilibrium depends on the sequence (mi). Theoretical results are compared with the available genomic data.
INFORMATION CONSERVATION IS FUNDAMENTAL: RECOVERING THE LOST INFORMATION IN HAWKING RADIATION
Authors: ZHANG BAOCHENG , CAI QING-YU , ZHAN MING-SHENG , YOU LI
Published: July 2013

In both classical and quantum world, information cannot appear or disappear. This fundamental principle, however, is questioned for a black hole, by the acclaimed "information loss paradox." Based on the conservation laws of energy, charge, and angular momentum, we recently show the total information encoded in the correlations among Hawking radiations equals exactly to the same amount previously considered lost, assuming the nonthermal spectrum of Parikh and Wilczek. Thus the information loss paradox can be falsified through experiments by detecting correlations, for instance, through measuring the covariances of Hawking radiations from black holes, such as the manmade ones speculated to appear in LHC experiments. The affirmation of information conservation in Hawking radiation will shine new light on the unification of gravity with quantum mechanics.
TREND PREDICTION IN TEMPORAL BIPARTITE NETWORKS: THE CASE OF MOVIELENS, NETFLIX, AND DIGG
Authors: ZENG AN , GUALDI STANISLAO , MEDO MATÚŠ , ZHANG YI-CHENG
Published: July 2013

Online systems, where users purchase or collect items of some kind, can be effectively represented by temporal bipartite networks where both nodes and links are added with time. We use this representation to predict which items might become popular in the near future. Various prediction methods are evaluated on three distinct datasets originating from popular online services (Movielens, Netflix, and Digg). We show that the prediction performance can be further enhanced if the user social network is known and centrality of individual users in this network is used to weight their actions.
ENTROPY-GROWTH-BASED MODEL OF EMOTIONALLY CHARGED ONLINE DIALOGUES
Authors: SIENKIEWICZ JULIAN , SKOWRON MARCIN , PALTOGLOU GEORGIOS , HOŁYST JANUSZ A.
Published: July 2013

We analyze emotionally annotated massive data from Internet relay chat (IRC) as well as from BBC forum website and model the dialogues between chat participants by assuming that the driving force for the discussion is the entropy growth of emotional probability distribution. This process is claimed to be responsible for a power-law distribution of the discussion lengths observed in the dialogues. We perform numerical simulations based on the noticed phenomenon obtaining a good agreement with the real data. Finally, we propose a method to artificially prolong the duration of the discussion that relies on the entropy of emotional probability distribution.
QUANTUM KEY DISTRIBUTION WITH REALISTIC HERALDED SINGLE-PHOTON SOURCES
Authors: LASOTA MIKOŁAJ , DEMKOWICZ-DOBRZAŃSKI RAFAŁ , BANASZEK KONRAD
Published: July 2013

We analyze theoretically the performance of four-state quantum key distribution protocols implemented with a realistic heralded single-photon source. The analysis assumes a noisy model for the detector heralding generation of individual photons via spontaneous parametric down-conversion, including dark counts and imperfect photon number resolution. We identify characteristics of the heralding detector that defines the attainable cryptographic key rate and the maximum secure distance. Approximate analytical formulas are applied to multiplexed detection and compared with results of numerical calculations.
ULTRA-LOW-ENERGY STRAINTRONICS USING MULTIFERROIC COMPOSITES
Authors: ROY KUNTAL
Published: July 2013

This paper reviews the recent developments on building nanoelectronics for our future information processing paradigm using multiferroic composites. With appropriate choice of materials, when a tiny voltage of few tens of millivolts is applied across a multiferroic composite, i.e., a piezoelectric layer stain-coupled with a magnetostrictive layer, the piezoelectric layer gets strained and the generated stress in the magnetostrictive layer switches the magnetization direction between its two stable states. We particularly review the switching dynamics of magnetization and calculation of associated metrics like switching delay and energy dissipation. Such voltage-induced magnetization switching mechanism dissipates a minuscule amount of energy of only ~ 1 attojoule in sub-nanosecond switching delay at room-temperature. The performance metrics for such nonvolatile straintronic devices make them very attractive for building not only memory devices but also building logic, so that they can be deemed suitable for computational purposes. Hence, multiferroic straintronics has profound promise of contributing to beyond Moore's law technology, i.e., of being possible replacement of conventional charge-based electronics, which is reaching its performance limit specifically due to excessive energy dissipation.
A survey on smartphone-based systems for opportunistic user context recognition
Authors: Hoseini-Tabatabaei Seyed Amir , Gluhak Alexander , Tafazolli Rahim
Published: July 2013

The ever-growing computation and storage capability of mobile phones have given rise to mobile-centric context recognition systems, which are able to sense and analyze the context of the carrier so as to provide an appropriate level of service. As nonintrusive autonomous sensing and context recognition are desirable characteristics of a personal sensing system; efforts have been made to develop opportunistic sensing techniques on mobile phones. The resulting combination of these approaches has ushered in a new realm of applications, namely
opportunistic user context recognition with mobile phones
.

This article surveys the existing research and approaches towards realization of such systems. In doing so, the typical architecture of a mobile-centric user context recognition system as a sequential process of
sensing
,
preprocessing
, and
context recognition
phases is introduced. The main techniques used for the realization of the respective processes during these phases are described, and their strengths and limitations are highlighted. In addition, lessons learned from previous approaches are presented as motivation for future research. Finally, several open challenges are discussed as possible ways to extend the capabilities of current systems and improve their real-world experience.
Recovery within long-running transactions
Authors: Colombo Christian , Pace Gordon J.
Published: July 2013

As computer systems continue to grow in complexity, the possibility of failure increases. At the same time, the increase in computer system pervasiveness in day-to-day activities bring along increased expectations on their reliability. This has led to the need for effective and automatic error-recovery techniques to resolve failures. Transactions enable the handling of failure propagation over concurrent systems due to dependencies, restoring the system to the point before the failure occurred. However, in various settings, especially when interacting with the real world, reversal is not possible. The notion of compensations has been long advocated as a way of addressing this issue, through the specification of activities which can be executed to undo partial transactions. Still, there is no accepted standard theory; the literature offers a plethora of distinct formalisms and approaches.

In this survey, we review the compensations from a theoretical point of view by (i) giving a historic account of the evolution of compensating transactions; (ii) delineating and describing a number of design options involved; (iii) presenting a number of formalisms found in the literature, exposing similarities and differences; (iv) comparing formal notions of compensation correctness; (v) giving insights regarding the application of compensations in practice; and (vi) discussing current and future research trends in the area.
Phase-change memory
Authors: Zilberberg Omer , Weiss Shlomo , Toledo Sivan
Published: July 2013

This article surveys the current state of phase-change memory (PCM) as a nonvolatile memory technology set to replace flash and DRAM in modern computerized systems. It has been researched and developed in the last decade, with researchers providing better architectural designs which address the technology's main challenges—its limited write endurance, potential long latency, high energy writes, power dissipation, and some concerns for memory privacy. Some physical properties of the technology are also discussed, providing a basis for architectural discussions. Also briefly shown are other architectural alternatives, such as FeRAM and MRAM. The designs surveyed in this article include read before write, wear leveling, write cancellation, write pausing, some encryption schemes, and buffer organizations. These allow PCM to stand on its own as a replacement for DRAM as main memory. Designs for hybrid memory systems with both PCM and DRAM are also shown and some designs for SSDs incorporating PCM.
A survey on cache tuning from a power/energy perspective
Authors: Zang Wei , Gordon-Ross Ann
Published: July 2013

Low power and/or energy consumption is a requirement not only in embedded systems that run on batteries or have limited cooling capabilities, but also in desktop and mainframes where chips require costly cooling techniques. Since the cache subsystem is typically the most power/energy-consuming subsystem, caches are good candidates for power/energy optimizations, and therefore, cache tuning techniques are widely researched. This survey focuses on state-of-the-art offline static and online dynamic cache tuning techniques and summarizes the techniques' attributes, major challenges, and potential research trends to inspire novel ideas and future research avenues.
Exploration and exploitation in evolutionary algorithms
Authors: Črepinšek Matej , Liu Shih-Hsi , Mernik Marjan
Published: July 2013

“Exploration and exploitation are the two cornerstones of problem solving by search.” For more than a decade, Eiben and Schippers' advocacy for balancing between these two antagonistic cornerstones still greatly influences the research directions of evolutionary algorithms (EAs) [1998]. This article revisits nearly 100 existing works and surveys how such works have answered the advocacy. The article introduces a fresh treatment that classifies and discusses existing work within three rational aspects: (1) what and how EA components contribute to exploration and exploitation; (2) when and how exploration and exploitation are controlled; and (3) how balance between exploration and exploitation is achieved. With a more comprehensive and systematic understanding of exploration and exploitation, more research in this direction may be motivated and refined.
Mathematical formalisms for performance evaluation of networks-on-chip
Authors: Kiasari Abbas Eslami , Jantsch Axel , Lu Zhonghai
Published: July 2013

This article reviews four popular mathematical formalisms—
queueing theory, network calculus, schedulability analysis
, and
dataflow analysis
—and how they have been applied to the analysis of on-chip communication performance in Systems-on-Chip. The article discusses the basic concepts and results of each formalism and provides examples of how they have been used in Networks-on-Chip (NoCs) performance analysis. Also, the respective strengths and weaknesses of each technique and its suitability for a specific purpose are investigated. An open research issue is a unified analytical model for a comprehensive performance evaluation of NoCs. To this end, this article reviews the attempts that have been made to bridge these formalisms.
Using targeted paraphrasing and monolingual crowdsourcing to improve translation
Authors: Resnik Philip , Buzek Olivia , Kronrod Yakov , Hu Chang , Quinn Alexander J. , Bederson Benjamin B.
Published: July 2013

Targeted paraphrasing is a new approach to the problem of obtaining cost-effective, reasonable quality translation, which makes use of simple and inexpensive human computations by monolingual speakers in combination with machine translation. The key insight behind the process is that it is possible to spot likely translation errors with only monolingual knowledge of the target language, and it is possible to generate alternative ways to say the same thing (i.e., paraphrases) with only monolingual knowledge of the source language. Formal evaluation demonstrates that this approach can yield substantial improvements in translation quality, and the idea has been integrated into a broader framework for monolingual collaborative translation that produces fully accurate, fully fluent translations for a majority of sentences in a real-world translation task, with no involvement of human bilingual speakers.
An abstractive approach to sentence compression
Authors: Cohn Trevor , Lapata Mirella
Published: July 2013

In this article we generalize the sentence compression task. Rather than simply shorten a sentence by deleting words or constituents, as in previous work, we rewrite it using additional operations such as substitution, reordering, and insertion. We present an experimental study showing that humans can naturally create abstractive sentences using a variety of rewrite operations, not just deletion. We next create a new corpus that is suited to the abstractive compression task and formulate a discriminative tree-to-tree transduction model that can account for structural and lexical mismatches. The model incorporates a grammar extraction method, uses a language model for coherent output, and can be easily tuned to a wide range of compression-specific loss functions.
An inference-based model of word meaning in context as a paraphrase distribution
Authors: Moon Taesun , Erk Katrin
Published: July 2013

Graded models of word meaning in context characterize the meaning of individual usages (occurrences) without reference to dictionary senses. We introduce a novel approach that frames the task of computing word meaning in context as a probabilistic inference problem. The model represents the meaning of a word as a probability distribution over potential paraphrases, inferred using an undirected graphical model. Evaluated on paraphrasing tasks, the model achieves state-of-the-art performance.
Pervasive social context
Authors: Schuster Daniel , Rosi Alberto , Mamei Marco , Springer Thomas , Endler Markus , Zambonelli Franco
Published: July 2013

As pervasive computing meets social networks, there is a fast growing research field called pervasive social computing. Applications in this area exploit the richness of information arising out of people using sensor-equipped pervasive devices in their everyday life combined with intense use of different social networking services. We call this set of information pervasive social context. We provide a taxonomy to classify pervasive social context along the dimensions space, time, people, and information source (STiPI) as well as commenting on the type and reason for creating such context. A survey of recent research shows the applicability and usefulness of the taxonomy in classifying and assessing applications and systems in the area of pervasive social computing. Finally, we present some research challenges in this area and illustrate how they affect the systems being surveyed.
Nontrivial landmark recommendation using geotagged photos
Authors: Shi Yue , Serdyukov Pavel , Hanjalic Alan , Larson Martha
Published: July 2013

Online photo-sharing sites provide a wealth of information about user behavior and their potential is increasing as it becomes ever-more common for images to be associated with location information in the form of geotags. In this article, we propose a novel approach that exploits geotagged images from an online community for the purpose of personalized landmark recommendation. Under our formulation of the task, recommended landmarks should be relevant to user interests and additionally they should constitute nontrivial recommendations. In other words, recommendations of landmarks that are highly popular and frequently visited and can be easily discovered through other information sources such as travel guides should be avoided in favor of recommendations that relate to users' personal interests. We propose a collaborative filtering approach to the personalized landmark recommendation task within a matrix factorization framework. Our approach, WMF-CR, combines weighted matrix factorization and category-based regularization. The integrated weights emphasize the contribution of nontrivial landmarks in order to focus the recommendation model specifically on the generation of nontrivial recommendations. They support the judicious elimination of trivial landmarks from consideration without also discarding information valuable for recommendation. Category-based regularization addresses the sparse data problem, which is arguably even greater in the case of our landmark recommendation task than in other recommendation scenarios due to the limited amount of travel experience recorded in the online image set of any given user. We use category information extracted from Wikipedia in order to provide the system with a method to generalize the semantics of landmarks and allow the model to relate them not only on the basis of identity, but also on the basis of topical commonality. The proposed approach is computational scalable, that is, its complexity is linear with the number of observed preferences in the user-landmark preference matrix and the number of nonzero similarities in the category-based landmark similarity matrix. We evaluate the approach on a large collection of geotagged photos gathered from Flickr. Our experimental results demonstrate that WMF-CR outperforms several state-of-the-art baseline approaches in recommending nontrivial landmarks. Additionally, they demonstrate that the approach is well suited for addressing data sparseness and provides particular performance improvement in the case of users who have limited travel experience, that is, have visited only few cities or few landmarks.
Semantic trajectories
Authors: Yan Zhixian , Chakraborty Dipanjan , Parent Christine , Spaccapietra Stefano , Aberer Karl
Published: July 2013

With the large-scale adoption of GPS equipped mobile sensing devices, positional data generated by moving objects (e.g., vehicles, people, animals) are being easily collected. Such data are typically modeled as streams of spatio-temporal (x,y,t) points, called
trajectories
. In recent years trajectory management research has progressed significantly towards efficient storage and indexing techniques, as well as suitable knowledge discovery. These works focused on the geometric aspect of the raw mobility data. We are now witnessing a growing demand in several application sectors (e.g., from shipment tracking to geo-social networks) on understanding the
semantic
behavior of moving objects. Semantic behavior refers to the use of semantic abstractions of the raw mobility data, including not only geometric patterns but also knowledge extracted jointly from the mobility data and the underlying geographic and application domains information. The core contribution of this article lies in a
semantic model
and a
computation and annotation platform
for developing a semantic approach that progressively transforms the raw mobility data into semantic trajectories enriched with segmentations and annotations. We also analyze a number of experiments we did with semantic trajectories in different domains.
Connecting people through physical proximity and physical resources at a conference
Authors: Chin Alvin , Xu Bin , Wang Hao , Chang Lele , Wang Hao , Zhu Lijun
Published: July 2013

This work investigates how to bridge the gap between offline and online behaviors at a conference and how the physical resources in the conference (the physical objects used in the conference for gathering attendees together in engaging an activity such as rooms, sessions, and papers) can be used to help facilitate social networking. We build Find and Connect, a system that integrates offline activities and interactions captured in real time with online connections in a conference environment, to provide a list of potential people one should connect to for forming an ephemeral social network. We investigate how social connections can be established and integrated with physical resources through positioning technology, and the relationship between physical proximity encounters and online social connections. Results from our two datasets of two trials, one at the UIC/ATC 2010 conference and GCJK internal marketing event, show that social connections that are reciprocal in relationship, such as friendship and exchanged contacts, have tighter, denser, and highly clustered networks compared to unidirectional relationships such as follow. We discover that there is a positive relationship between physical proximity encounters and online social connections before the social connection is made for friends, but a negative relationship for after the social connection is made. The first indicates social selection is strong, and the second indicates social influence is weak. Even though our dataset is sparse, nonetheless we believe our work is promising and novel which is worthy of future research.
Lexical semantic factors in the acceptability of english support-verb-nominalization constructions
Authors: Davis Anthony R. , Barrett Leslie
Published: July 2013

We explore the properties of support-verb and nominalization (SVN) pairs in English, a type of multiword expression in which a semantically impoverished verb combines with a complement nominalization sharing an unexpressed role with the verb. This study follows others in seeking syntactic or lexical semantic factors correlated with the acceptability of these constructions. In particular, following recent work showing certain semantic verb class features to improve SVN classification [Tu and Roth 2011], we explore the possibility that support verbs and the verbal roots of nominalizations in acceptable SVN pairs are clustered according to the classes of Levin [1993]. We compare the compatibility correlation of these results with those of the Aktionsart-class-based proposal of Barrett and Davis [2002]. We find the evidence that Levin classes are a factor in the acceptability of SVN constructions to be equivocal, and conclude with a discussion of the reasons for this finding.
Learning to detect english and hungarian light verb constructions
Authors: Vincze Veronika , Nagy T. István , Zsibrita János
Published: July 2013

Light verb constructions consist of a verbal and a nominal component, where the noun preserves its original meaning while the verb has lost it (to some degree). They are syntactically flexible and their meaning can only be partially computed on the basis of the meaning of their parts, thus they require special treatment in natural language processing. For this purpose, the first step is to identify light verb constructions.

In this study, we present our conditional random fields-based tool—called FXTagger—for identifying light verb constructions. The flexibility of the tool is demonstrated on two, typologically different, languages, namely, English and Hungarian. As earlier studies labeled different linguistic phenomena as light verb constructions, we first present a linguistics-based classification of light verb constructions and then show that FXTagger is able to identify different classes of light verb constructions in both languages.

Different types of texts may contain different types of light verb constructions; moreover, the frequency of light verb constructions may differ from domain to domain. Hence we focus on the portability of models trained on different corpora, and we also investigate the effect of simple domain adaptation techniques to reduce the gap between the domains. Our results show that in spite of domain specificities, out-domain data can also contribute to the successful LVC detection in all domains.
Wireless noncontact ECG and EEG biopotential sensors
Authors: Chi Yu M. , Ng Patrick , Cauwenberghs Gert
Published: July 2013

Wearable, unobtrusive and patient friendly physiological sensors will be a key driving force in the wireless health revolution. Cardiac (ECG) and brain (EEG) signals are two important signal modalities indicative of healthy and diseased states of body and mind that directly benefit from long-term monitoring. Despite advancements in wireless and embedded electronics technology, however, ECG/EEG monitoring devices still face problems with patient compliance and comfort from the use wet/gel electrodes. We have developed two wireless biopotential instrumentation systems using noncontact electrodes that can operate without direct skin contact and through thin layers of fabric. The first system is a general purpose replacement for traditional ECG/EEG telemetry systems and the second is a compact, fully self-contained wireless ECG tag. All of the issues relating to the design of low noise, high performance noncontact sensors are discussed along with full technical details, circuit schematics and construction techniques. The noncontact electrode has been integrated into both a wearable ECG chest harness as well an EEG headband and characterized in a battery of experiments that represent potential health applications including resting ECG, exercise ECG and EEG directly against standard clinical adhesive Ag/AgCl electrodes. With careful design and secure mechanical harnesses the noncontact sensor is capable of approaching the quality of conventional electrodes.
Expanding our visions of citizen science
Authors: Kuznetsov Stacey
Published: July 2013

Community + Culture features practitioner perspectives on designing technologies for and with communities. We highlight compelling projects and provocative points of view that speak to both community technology practice and the interaction design field as a whole.

Christopher A. Le Dantec
Smart societies
Authors: Monroy-Hernández Andrés , Farnham Shelly , Kiciman Emre , Counts Scott , De Choudhury Munmun
Published: July 2013

Social media has become globally ubiquitous, transforming how people are networked and mobilized. This forum explores research and applications of these new networked publics at individual, organizational, and societal levels.

Shelly Farnham, Editor
Information recall task impact in olfaction-enhanced multimedia
Authors: Ademoye Oluwakemi A. , Ghinea Gheorghita
Published: July 2013

Enhancing multimedia applications with olfactory sensations is one of the last challenges in the area. While there is evidence, both scientific and anecdotal, that olfactory cues help users in information recall tasks, there is a lack of work when the targeted information is one contained in a multimedia presentation, which is precisely the focus of this article. Accordingly, we present the results of two experimental studies. The first study measured the impact of olfactory media variation on the user's ability to perceive, synthesize, and analyze the informational content of olfactory-enhanced multimedia videos; the second study measured the impact of information content, and an information recall task in respect of user perception of the relevance, sense of reality, and acceptability of the olfactory media content, as well as the overall enjoyment of the experience. Results show that the use of olfactory media content, both pleasant and unpleasant, in multimedia displays does not significantly impact on information assimilation in a negative way. Moreover, the addition of a performance task may enhance the user's understanding of the correlation between the characteristic odor(s) and the scenario under consideration, as well as enable users to consciously learn the odors.
GPUDet
Authors: Jooybar Hadi , Fung Wilson W.L. , O'Connor Mike , Devietti Joseph , Aamodt Tor M.
Published: July 2013

Nondeterminism is a key challenge in developing multithreaded applications. Even with the same input, each execution of a multithreaded program may produce a different output. This behavior complicates debugging and limits one's ability to test for correctness. This non-reproducibility situation is aggravated on massively parallel architectures like graphics processing units (GPUs) with thousands of concurrent threads. We believe providing a deterministic environment to ease debugging and testing of GPU applications is essential to enable a broader class of software to use GPUs.

Many hardware and software techniques have been proposed for providing determinism on general-purpose multi-core processors. However, these techniques are designed for small numbers of threads. Scaling them to thousands of threads on a GPU is a major challenge. This paper proposes a scalable hardware mechanism, GPUDet, to provide determinism in GPU architectures. In this paper we characterize the existing deterministic and nondeterministic aspects of current GPU execution models, and we use these observations to inform GPUDet's design. For example, GPUDet leverages the inherent determinism of the SIMD hardware in GPUs to provide determinism within a wavefront at no cost. GPUDet also exploits the Z-Buffer Unit, an existing GPU hardware unit for graphics rendering, to allow parallel out-of-order memory writes to produce a deterministic output. Other optimizations in GPUDet include deterministic parallel execution of atomic operations and a workgroup-aware algorithm that eliminates unnecessary global synchronizations.

Our simulation results indicate that GPUDet incurs only 2X slowdown on average over a baseline nondeterministic architecture, with runtime overheads as low as 4% for compute-bound applications, despite running GPU kernels with thousands of threads. We also characterize the sources of overhead for deterministic execution on GPUs to provide insights for further optimizations.
DeNovoND
Authors: Sung Hyojin , Komuravelli Rakesh , Adve Sarita V.
Published: July 2013

Recent work has shown that disciplined shared-memory programming models that provide deterministic-by-default semantics can simplify both parallel software and hardware. Specifically, the DeNovo hardware system has shown that the software guarantees of such models (e.g., data-race-freedom and explicit side-effects) can enable simpler, higher performance, and more energy-efficient hardware than the current state-of-the-art
for deterministic programs
. Many applications, however, contain non-deterministic parts; e.g., using lock synchronization. For commercial hardware to exploit the benefits of DeNovo, it is therefore necessary to extend DeNovo to support non-deterministic applications.

This paper proposes DeNovoND, a system that supports lock-based, disciplined non-determinism, with the simplicity, performance, and energy benefits of DeNovo. We use a combination of distributed queue-based locks and access signatures to implement simple memory consistency semantics for safe non-determinism, with a coherence protocol that does not require transient states, invalidation traffic, or directories, and does not incur false sharing. The resulting system is simpler, shows comparable or better execution time, and has 33% less network traffic on average (translating directly into energy savings) relative to a state-of-the-art invalidation-based protocol for 8 applications designed for lock synchronization.
Parallelizing data race detection
Authors: Wester Benjamin , Devecsery David , Chen Peter M. , Flinn Jason , Narayanasamy Satish
Published: July 2013

Detecting data races in multithreaded programs is a crucial part of debugging such programs, but traditional data race detectors are too slow to use routinely. This paper shows how to speed up race detection by spreading the work across multiple cores. Our strategy relies on
uniparallelism
, which executes time intervals of a program (called
epochs
) in parallel to provide scalability, but executes all threads from a single epoch on a single core to eliminate locking overhead. We use several techniques to make parallelization effective: dividing race detection into three phases, predicting a subset of the analysis state, eliminating sequential work via transitive reduction, and reducing the work needed to maintain multiple versions of analysis via factorization. We demonstrate our strategy by parallelizing a happens-before detector and a lockset-based detector. We find that uniparallelism can significantly speed up data race detection. With 4x the number of cores as the original application, our strategy speeds up the median execution time by 4.4x for a happens-before detector and 3.3x for a lockset race detector. Even on the same number of cores as the conventional detectors, the ability for uniparallelism to elide analysis locks allows it to reduce the median overhead by 13% for a happens-before detector and 8% for a lockset detector.
Power containers
Authors: Shen Kai , Shriraman Arrvindh , Dwarkadas Sandhya , Zhang Xiao , Chen Zhuan
Published: July 2013

Energy efficiency and power capping are critical concerns in server and cloud computing systems. They face growing challenges due to dynamic power variations from new client-directed web applications, as well as complex behaviors due to multicore resource sharing and hardware heterogeneity. This paper presents a new operating system facility called "power containers" that accounts for and controls the power and energy usage of individual fine-grained requests in multicore servers. This facility relies on three key techniques---1) online model that attributes multicore power (including shared maintenance power) to concurrently running tasks, 2) alignment of actual power measurements and model estimates to enable online model recalibration, and 3) on-the-fly application-transparent request tracking in multi-stage servers to isolate the power and energy contributions and customize per-request control. Our mechanisms enable new multicore server management capabilities including fair power capping that only penalizes power-hungry requests, and energy-aware request distribution between heterogeneous servers. Our evaluation uses three multicore processors (Intel Woodcrest, Westmere, and SandyBridge) and a variety of server and cloud computing (Google App Engine) workloads. Our results demonstrate the high accuracy of our request power accounting (no more than 11% errors) and the effectiveness of container-enabled power virus isolation and throttling. Our request distribution case study shows up to 25% energy saving compared to an alternative approach that recognizes machine heterogeneity but not fine-grained workload affinity.