bluuebunny/crossref_metadata_2025 huggingface dataset:
Active Joint Stiffness Regulation to Achieve Isotropic Compliance in the Euclidean Space
Authors: Belfiore Nicola P. , Verotti Matteo , Di Giamberardino Paolo , Rudas Imre J.
Published: September 2012

This paper is dedicated to the relationship between the external force applied on a point of a robot end-effector and its consequent displacement in static conditions. Both the force and the displacement are herein considered in the Euclidean space E(3). This fact represents a significant simplification of the approach, since it avoids some problems related to the absence of a natural positive definite metric on the Special Euclidean Group SE(3). On the other hand, such restriction allows the method to find closed-form solutions to a large class of problems in robot statics. The peculiar goal of this investigation consists of setting up a procedure which guarantees at least one pose at which any force applied (in E(3)) to an end-effector point is always parallel to its consequent displacement (also in E(3)). This property, which will be referred to as isotropic compliance in E(3), makes the robot tip static behavior uniform with respect to all directions, namely, isotropic, although not homogeneous, since it holds only in some poses. Achieving isotropic compliance in E(3) is a task more general than the classical problem of finding a pose with unit condition number, which does not include the case of different elements in the diagonal joint stiffness matrix. For this reason, the object of the present investigation could not be furtherer simplified to the classical kinetostatic problem in terms of the jacobian matrix alone. The paper reveals how the force–displacement parallelism can be achieved by using a method based on a simple proportional-derivative (PD) controller strategy. The method can be applied when the passive and active stiffness act, on the joints, either in parallel or in series, and the magnitude of the displacement response can be chosen by imposing appropriate values for the overall joints compliance. Results show that for the three analyzed examples, namely, the RR, RRP, and RRR manipulators, with arbitrary lengths of the links, there is, at least, one pose for which the sought property is achieved.
KPC-9, a Novel Carbapenemase from Clinical Specimens in Israel
Authors: Hidalgo-Grass Carlos , Warburg Gabriela , Temper Violeta , Benenson Shmuel , Moses Allon E. , Block Colin , Strahilevitz Jacob
Published: September 2012

A
bla
KPC-9
carbapenemase variant was discovered in isolates of
Klebsiella pneumoniae
and
Escherichia coli
from a single patient. It differed from
bla
KPC-3
by one amino acid substitution (Val239Ala). The
K. pneumoniae
isolate was typed as ST258, as was the epidemic Israeli KPC-3 clone.
bla
KPC-9
was found on a plasmid indistinguishable from pKpQIL that carries
bla
KPC-3
in the epidemic clone. Compared to KPC-3, KPC-9 conferred less resistance to carbapenems and higher resistance to ceftazidime.
In Vitro
Antifungal Activity of Isavuconazole against Madurella mycetomatis
Authors: Kloezen Wendy , Meis Jacques F. , Curfs-Breuker Ilse , Fahal Ahmed H. , van de Sande Wendy W. J.
Published: September 2012

Currently, therapy of black-grain mycetoma caused by
Madurella mycetomatis
consists of extensive debridement of the infected tissue combined with prolonged antifungal therapy with ketoconazole or itraconazole. In the present study, the
in vitro
activity of the new triazole isavuconazole toward
M. mycetomatis
was evaluated. Isavuconazole appeared to have high activity against
M. mycetomatis
, with MICs ranging from ≤0.016 to 0.125 μg/ml. Due to its favorable pharmacokinetics, isavuconazole could be a promising antifungal agent in the treatment of mycetoma.
Virulence Phenotypes of Legionella pneumophila Associated with Noncoding RNA lpr0035
Authors: Jayakumar Deepak , Early Julie V. , Steinman Howard M.
Published: September 2012

The Philadelphia-1 strain ofLegionella pneumophila, the causative organism of Legionnaires' disease, contains a recently discovered noncoding RNA, lpr0035. lpr0035 straddles the 5′ chromosomal junction of a 45-kbp mobile genetic element, pLP45, which can exist as an episome or integrated in the bacterial chromosome. A 121-bp deletion was introduced in strain JR32, a Philadelphia-1 derivative. The deletion inactivated lpr0035, removed the 49-bp direct repeat at the 5′ junction of pLP45, and locked pLP45 in the chromosome. Intracellular multiplication of the deletion mutant was decreased by nearly 3 orders of magnitude inAcanthamoeba castellaniiamoebae and nearly 2 orders of magnitude in J774 mouse macrophages. Entry of the deletion mutant into amoebae and macrophages was decreased by >70%. The level of entry in both hosts was restored to that in strain JR32 by plasmid copies of two open reading frames immediately downstream of the 5′ junction and plasmid lpr0035 driven by its endogenous promoter. When induced from atacpromoter, plasmid lpr0035 completely reversed the intracellular multiplication defect in macrophages but was without effect in amoebae. These data are the first evidence of a role for noncoding RNA lpr0035, which has homologs in six otherLegionellagenomes, in entry ofL. pneumophilainto amoebae and macrophages and in host-specific intracellular multiplication. The data also demonstrate that deletion of a direct-repeat sequence restricts the mobility of pLP45 and is a means of studying the role of pLP45 mobility inLegionellavirulence phenotypes.
Enteropathogenic Escherichia coli and Vaccinia Virus Do Not Require the Family of WASP-Interacting Proteins for Pathogen-Induced Actin Assembly
Authors: Garber John J. , Takeshima Fuminao , Antón Inés M. , Oyoshi Michiko K. , Lyubimova Anna , Kapoor Archana , Shibata Tomoyuki , Chen Feng , Alt Frederick W. , Geha Raif S. , Leong John M. , Snapper Scott B.
Published: September 2012

The human pathogens enteropathogenic
Escherichia coli
(EPEC) and vaccinia virus trigger actin assembly in host cells by activating the host adaptor Nck and the actin nucleation promoter neural Wiskott-Aldrich syndrome protein (N-WASP). EPEC translocates effector molecules into host cells via type III secretion, and the interaction between the translocated intimin receptor (Tir) and the bacterial membrane protein intimin stimulates Nck and N-WASP recruitment, leading to the formation of actin pedestals beneath adherent bacteria. Vaccinia virus also recruits Nck and N-WASP to generate actin tails that promote cell-to-cell spread of the virus. In addition to Nck and N-WASP, WASP-interacting protein (WIP) localizes to vaccinia virus tails, and inhibition of actin tail formation upon ectopic expression of WIP mutants led to the suggestion that WIP is required for this process. Similar studies of WIP mutants, however, did not affect the ability of EPEC to form actin pedestals, arguing against an essential role for WIP in EPEC-induced actin assembly. In this study, we demonstrate that Nck and N-WASP are normally recruited by vaccinia virus and EPEC in the absence of WIP, and neither WIP nor the WIP family members CR16 and WIRE/WICH are essential for pathogen induced actin assembly. In addition, although Nck binds EPEC Tir directly, N-WASP is required for its localization during pedestal formation. Overall, these data highlight similar pathogenic strategies shared by EPEC and vaccinia virus by demonstrating a requirement for both Nck and N-WASP, but not WIP or WIP family members in pathogen-induced actin assembly.
Liver abscess caused by toothpick and treated by laparoscopic left hepatic resection: case report and literature review
Authors: Abu-Wasel Bassam , Eltawil Karim M , Keough Valerie , Molinari Michele
Published: September 2012

Hepatic abscesses caused by ingested foreign bodies have been reported in the medical literature but represent very uncommon events. Extra-luminal migration of sawing needles and pins is the most common cause of perforation of the gastrointestinal tract associated with liver infections. Other non-metallic sharp objects such as animal bones and toothpicks have been described but are less frequent. The authors present a case of a 45-year-old woman who suffered from sepsis and a liver abscess because of the migration of a toothpick that lodged in the left hepatic lobe. Review of the literature on the pathogenesis and clinical management of liver abscesses caused by ingested foreign is presented.
BCG vaccination in England since 2005: a survey of policy and practice
Authors: Pilger Daniel , Nguipdop-Djomo Patrick , Abubakar Ibrahim , Elliman David , Rodrigues Laura C , Watson John M , Eastman Vera , Mangtani Punam
Published: September 2012

Objective

Assess the current BCG vaccination policies and delivery pathways for immunisation in Primary Care Trusts (PCTs) in England since the 2005 change in recommendations.

Design

A survey of key informants across PCTs using a standardised, structured questionnaire.

Setting

152 PCTs in England.

Results

Complete questionnaires were returned from 127 (84%) PCTs. Sixteen (27%) PCTs reported universal infant vaccination and 111 (73%) had selective infant vaccination. Selective vaccination outside infancy was also reported from 94 (74%) PCTs. PCTs with selective infant policy most frequently vaccinated on postnatal wards (51/102, 50%), whereas PCTs with universal infant vaccination most frequently vaccinated in community clinics (9/13, 69%; p=0.011). To identify and flag up eligible infants in PCTs with targeted infant immunisation, those who mostly vaccinate on postnatal wards depend on midwives and maternity records, whereas those who vaccinate primarily in the community rely more often on various healthcare professionals.

Conclusions

Targeted infant vaccination has been implemented in most PCTs across the UK. PCTs with selective infant vaccination provide BCG vaccine via a greater variety of healthcare professionals than those with universal infant vaccination policies. Data on vaccine coverage would help evaluate the effectiveness of delivery. Interruptions of delivery noted here emphasise the importance of not just an agreed, standardised, local pathway, but also a named person in charge.
STUDY OF NUCLEAR BOUND STATES USING MEAN-FIELD WOODS–SAXON AND SPIN-ORBIT POTENTIALS
Authors: PAHLAVANI M. R. , ALAVI S. A.
Published: September 2012

The neutron single-particle bound states as solutions of radial Schrödinger equation for the central Woods–Saxon potential together with spin-orbit interaction and centrifugal terms have been obtained analytically. By introducing new variable and using Taylor expansion, the differential equation has been transformed to solvable hypergeometric type. This differential equation has also been solved using Nikiforov–Uvarov (NU) method. Neutron single-particle states have been derived as self-adjoint form of hypergeometric series. By means of boundary conditions, which implies eigenvalue condition as complicated relation between energy eigenvalues and parameters of nuclear potential, the neutron single-particle energy eigenvalues have been derived using graphical method. To examine method, numerical results in special cases of S states are evaluated. Results obtained using this method are in satisfactory agreements with available numerical solutions.
VISUAL ANALYSIS OF RESIDUALS FROM DATA-BASED MODELS IN COMPLEX INDUSTRIAL PROCESSES
Authors: ORDOÑEZ DANIEL G. , CUADRADO ABEL A. , DÍAZ IGNACIO , GARCÍA FRANCISCO J. , DÍEZ ALBERTO B. , FUERTES JUAN J.
Published: September 2012

The use of data-based models for visualization purposes in an industrial background is discussed. Results using Self-Organizing Maps (SOM) show how through a good design of the model and a proper visualization of the residuals generated by the model itself, the behavior of essential parameters of the process can be easily tracked in a visual way. Real data from a cold rolling facility have been used to prove the advantages of these techniques.
SET-VALUED DYNAMICS IN PROBLEMS OF MATHEMATICAL THEORY OF CONTROL PROCESSES
Authors: FILIPPOVA TATIANA
Published: September 2012

The dynamics and properties of set-valued states of differential control systems with uncertainties in initial data are studied. It is assumed that the dynamical system has a special structure, in which nonlinear terms in the right-hand sides of related differential equations are quadratic in state coordinates. We construct external and internal ellipsoidal estimates of reachable sets of nonlinear control system and find differential equations of proposed ellipsoidal estimates of reachable sets of nonlinear control system. The results obtained for quadratic system nonlinearities are extended to other types of control systems under uncertainty.
BIFURCATION ANALYSIS OF DAMPED VISCO-ELASTIC PLANAR BEAMS UNDER SIMULTANEOUS GRAVITATIONAL AND FOLLOWER FORCES
Authors: LUONGO ANGELO , D'ANNIBALE FRANCESCO
Published: September 2012

The mechanical behavior of a non-conservative non-linear beam, internally and externally damped, undergoing codimension-1 (static or dynamic) and codimension-2 (double-zero) bifurcations, is analyzed. The system consists of a purely flexible, planar, visco-elastic beam, fixed at one end, loaded at the tip by a follower force and a dead load, acting simultaneously. An integro-differential equation of motion in the transversal displacement, with relevant boundary conditions, is derived. Then, the linear stability diagram of the trivial rectilinear configuration is built-up in the space of the two loading parameters. Attention is then focused on the double-zero bifurcation, for which a post-critical analysis is carried out without any a-priori discretization. An adapted version of the Multiple Scale Method, based on a fractional series expansion in the perturbation parameter, is employed to derive the bifurcation equations. Finally, bifurcation charts are evaluated, able to illustrate the system behavior around the codimension-2 bifurcation point.
SPIN-DEPENDENT ELECTRON TRANSPORT IN A QUANTUM WIRE WITH FINITE WIDTH MODULATED BY MAGNETIC-ELECTRIC BARRIERS
Authors: LU JIAN-DUO , XU BIN , ZHENG WEI
Published: September 2012

We theoretically present the spin-dependent electron transport in a two-dimensional electron gas (2DEG) with finite width modulated by magnetic–electric barriers. It is found that the transmission probability and the spin polarization are strongly dependent on the height of the electric barrier, the energy of the incident electron, the distance between the two magnetic fields, and the width of the 2DEG. These may be useful for making the practical devices.
INVESTIGATION OF SPACE CHARGE TRAP LEVELS IN Al2O3 NANO-POWDER DOPED POLYETHYLENE BY PHOTO-STIMULATED DISCHARGE METHOD
Authors: ZHU ZHIEN , ZHANG YEWEN , AN ZHENLIAN , ZHENG FEIHU
Published: September 2012

The trap levels of Al 2 O 3 nano-powder doped LDPE with different Al 2 O 3 contents are investigated by PSD technique. The variation of trap depth in the doped LDPE can be qualitatively estimated by PSD spectra in continuous scanning method, and the distribution of trap levels in the samples can be quantitatively described in step scanning method. It is indicated that the trap levels of LDPE can be evidently deepened by Al 2 O 3 nano-powder doping with the content more than 0.1 wt%. According to the relative reports on the effect of nano-powder doping to space charge injection, it is considered that the suppression of space charge is probably correlated to the deeper trap levels in Al 2 O 3 nano-powder doped LDPE.
THERMODYNAMIC PROPERTIES OF AN ELECTRON GAS SYSTEM TRAPPED WITHIN VARIOUS SHAPES OF POTENTIALS
Authors: GÜLVEREN BERNA
Published: September 2012

The Thomas–Fermi (TF) equation is solved numerically for an electron gas system that interacts via the Coulomb potential. An emphasis is placed on how certain physical properties, such as the chemical potential and the total energy, change with the shape of the confinement at finite temperatures. By comparing these results with the results calculated for the noninteracting case, we are able to analyze how the inter-particle forces affect the thermodynamic properties of electrons. It is shown that the total energy and other properties of an electron gas is very sensitive to the particle interactions and the shape of the confining potential, even at high temperatures. The results are also applicable to nanostructures like two-dimensional quantum dot systems, wires.
EFFECT OF REPETITIVE PULSED LASER IRRADIATION ON PLASMA PLUME EMISSION INTENSITY AND SURFACE MORPHOLOGY OF 15 MeV ELECTRON-DEFECTED SILICON
Authors: SIRAJ K. , SHOAIB M. , ALI SAQIB , RAFIQUE M. S. , SAIF-UR-REHMAN
Published: September 2012

In this work, laser induced plasma plume intensity and surface morphology of electron-defected silicon have been studied. For this purpose, the silicon (1 1 1) was irradiated with 15 MeV electrons at different doses (2000–10,000 cGy). The electron-defected silicon samples were analyzed by XRD and SEM, showing increase in number of defects (incubation or absorption centers) by increasing electron dose. Afterward, repetitive Nd:YAG laser pulses were applied to electron-defected silicon. The plasma plume due to each laser pulse was photographed by computer controlled image capture system. From the images, the integrated intensity of plasma plume was calculated by image processing software and plotted as a function of number of laser pulses. The plasma plume intensity was found to increase linearly with increasing pulse number for all silicon samples. The integrated intensity of plasma plume also increases for those silicon samples which were irradiated at higher electron doses. The surface morphology of laser-ablated electron-defected samples was examined through SEM showing different phenomena, like thermal, electronic and hydrodynamic sputtering processes along with the formation of cone, craters, re-deposition of material, heat affected zone (HAZ) and debris formation.
X-RAY STUDIES OF BIOLOGICAL MATTER IN MICROFLUIDIC ENVIRONMENTS
Authors: KÖSTER SARAH , PFOHL THOMAS
Published: September 2012

Biological systems such as cells and cellular components are governed by processes, which take place on nanometer to micrometer length scales. X-ray scattering, diffraction and imaging techniques are extremely well suited to study these processes as the spatial resolution extends well into the relevant length scales. At the same time, the investigation of physical and chemical properties and behavior of such systems requires well-defined and controllable sample environments. One successful way to establish such environments, including specified flow fields, concentration gradients and confinement regimes is by employing microfluidic technology tailored to the particular scientific question. This brief review focuses on microfluidic techniques that have been used to investigate biological matter by X-rays. In particular, we show how the characteristics of flow on the micron scale enable new scientific approaches as compared to macroscale experiments.
MODE ANALYSIS AND SYSTEMATICAL DESIGN OF WIDE-BANDWIDTH PHOTONIC CRYSTAL 60° WAVEGUIDE BENDS WITH HIGH TRANSMISSION
Authors: CHEN TAO , ZHENG CAILONG , LI JINXING
Published: September 2012

We present a procedure to enhance the transmission efficiency of a photonic crystal slab waveguide bend by introducing an air hole with the same radius at the center of bend and optimizing the positions of three neighboring holes in the corner. The improvement relies only on the method of displacing holes which is technologically preferred to controlling variations in hole size or shape. We employ the effective refractive index approach and two-dimensional plane wave expansion method to analyze the guide modes of the straight waveguide and waveguide bend. The transmission character of bent waveguides is investigated using two-dimensional finite-difference time-domain method. Numerical studies demonstrate that the approximate method of mode analysis is unsuitable to our model. Alternatively, we systematically study the effect of different positions of the holes on the transmission. The optimized bends for the high transmission with broad bandwidth are proposed.
IIVFDT: IGNORANCE FUNCTIONS BASED INTERVAL-VALUED FUZZY DECISION TREE WITH GENETIC TUNING
Authors: SANZ J. , BUSTINCE H. , FERNÁNDEZ A. , HERRERA F.
Published: September 2012

The choice of membership functions plays an essential role in the success of fuzzy systems. This is a complex problem due to the possible lack of knowledge when assigning punctual values as membership degrees. To face this handicap, we propose a methodology called Ignorance functions based Interval-Valued Fuzzy Decision Tree with genetic tuning, IIVFDT for short, which allows to improve the performance of fuzzy decision trees by taking into account the ignorance degree. This ignorance degree is the result of a weak ignorance function applied to the punctual value set as membership degree.

Our IIVFDT proposal is composed of four steps: (1) the base fuzzy decision tree is generated using the fuzzy ID3 algorithm; (2) the linguistic labels are modeled with Interval-Valued Fuzzy Sets. To do so, a new parametrized construction method of Interval-Valued Fuzzy Sets is defined, whose length represents such ignorance degree; (3) the fuzzy reasoning method is extended to work with this representation of the linguistic terms; (4) an evolutionary tuning step is applied for computing the optimal ignorance degree for each Interval-Valued Fuzzy Set.

The experimental study shows that the IIVFDT method allows the results provided by the initial fuzzy ID3 with and without Interval-Valued Fuzzy Sets to be outperformed. The suitability of the proposed methodology is shown with respect to both several state-of-the-art fuzzy decision trees and C4.5. Furthermore, we analyze the quality of our approach versus two methods that learn the fuzzy decision tree using genetic algorithms. Finally, we show that a superior performance can be achieved by means of the positive synergy obtained when applying the well known genetic tuning of the lateral position after the application of the IIVFDT method.
A FILTER PROPOSAL FOR INCLUDING FEATURE CONSTRUCTION IN A GENETIC LEARNING ALGORITHM
Authors: GARCIA DAVID , GONZALEZ ANTONIO , PEREZ RAUL
Published: September 2012

In system identification process often a predetermined set of features is used. However, in many cases it is difficult to know a priori whether the selected features were really the more appropriate ones. This is the reason why the feature construction techniques have been very interesting in many applications. Thus, the current proposal introduces the use of these techniques in order to improve the description of fuzzy rule-based systems. In particular, the idea is to include feature construction in a genetic learning algorithm. The construction of attributes in this study will be restricted to the inclusion of functions defined on the initial attributes of the system. Since the number of functions and the number of attributes can be very large, a filter model, based on the use of information measures, is introduced. In this way, the genetic algorithm only needs to explore the particular new features that may be of greater interest to the final identification of the system. In order to manage the knowledge provided by the new attributes based on the use of functions we propose a new model of rule by extending a basic learning fuzzy rule-based model. Finally, we show the experimental study associated with this work.
INDUCING FUZZY REGRESSION TREE FORESTS USING ARTIFICIAL IMMUNE SYSTEMS
Authors: GASIR FATHI , CROCKETT KEELEY , BANDAR ZUHAIR
Published: September 2012

Fuzzy decision forests aim to improve the predictive power of single fuzzy decision trees by allowing multiple views of the same domain to be modelled. Such forests have been successfully created for classification problems where the outcome field is discrete; however predicting a continuous output value is more challenging in combining the output from multiple fuzzy decision trees. This paper presents a new approach to creating fuzzy regression tree forests based upon the induction of multiple fuzzy regression decision trees from one training sample, where each tree will represent a different view of the data domain. The singular fuzzy regression trees are induced using a proven algorithm known as Elgasir which fuzzifies crisp CHAID decision trees using trapezoidal membership functions for fuzzification and applies Takagi-Sugeno inference to obtain the final predicted values. A modified version of Artificial Immune System Network model (opt-aiNet) is then used for the simultaneous optimization of the membership functions across all trees within the forest. A strength of the proposed method is that data does not require fuzzification before forest induction this reducing pre-processing time and the need for subjective human experts. Five problem sets from the UCI repository and KEEL repository are used to evaluate the approach. The experimental results have shown that fuzzy regression tree forests reduce the error rate compared with single fuzzy regression trees.
UNIVERSAL IMAGE NOISE REMOVAL FILTER BASED ON TYPE-2 FUZZY LOGIC SYSTEM AND QPSO
Authors: ZHAI DAOYUAN , HAO MINSHEN , MENDEL JERRY
Published: September 2012

Removing Mixed Gaussian and Impulse Noise (MGIN) is considered to be one of the most essential topics in the domain of image restoration, and it is much more challenging than to remove pure Gaussian or impulse noise separately. Therefore, relatively fewer works have been published in this area. This paper proposes a new integrated approach for MGIN removal that is based on a Non-Singleton Interval Type-2 (NS-IT2) Fuzzy Logic System (FLS), and explains how to design such a NS-IT2 FLS using a Quantum-behaved Particle Swarm Optimization (QPSO) algorithm. Then the paper goes on to introduce two supplementary components, a Block-Matching 3-Dimensional Discrete Cosine Transformation (BM3D DCT) filter and a contrast scaling filter, which augment the overall performance of the NS-IT2 FLS. Finally, the paper shows that this proposed approach indeed provides both quantitatively and visually much better results compared to other often-used non-fuzzy techniques as well as its Type-1 (T1) and singleton IT2 (S-IT2) counterparts.
RECENT PROGRESS OF PERPENDICULAR ANISOTROPY MAGNETIC TUNNEL JUNCTIONS FOR NONVOLATILE VLSI
Authors: IKEDA SHOJI , SATO HIDEO , YAMANOUCHI MICHIHIKO , GAN HUADONG , MIURA KATSUYA , MIZUNUMA KOTARO , KANAI SHUN , FUKAMI SHUNSUKE , MATSUKURA FUMIHIRO , KASAI NAOKI , OHNO HIDEO
Published: September 2012

We review recent developments in magnetic tunnel junctions with perpendicular easy axis (p-MTJs) for nonvolatile very large scale integrated circuits (VLSIs). So far, a number of material systems such as rare-earth/transition metal alloys, L10-ordered ( Co, Fe )– Pt alloys, Co /( Pd, Pt ) multilayers, and ferromagnetic-alloy/oxide stacks have been proposed as electrodes in p-MTJs. Among them, p-MTJs with single or double ferromagnetic-alloy/oxide stacks, particularly CoFeB–MgO , were shown to have high potential to satisfy major requirements for integration.
Sedimentological controls on the fracture distribution and network development in Mesaverde Group sandstone lithofacies, Uinta Basin, Utah, USA
Authors: Sonntag Ryan , Evans James P. , La Pointe Paul , Deraps Meagan , Sisley Hope , Richey David
Published: September 2012

The Mesaverde Group, Uinta Basin, Utah is the source of current significant natural gas production and contains several trillion cubic feet of undiscovered natural gas resources. To evaluate and model the potential connectivity of hydraulically induced fractures to natural fractures in the subsurface, the natural fracture network was examined using scanline sampling, image and well logs, core and microstructural analyses. Regional fracture sets include subvertical fractures with dominant orientations of: north–south (006–015°), NE (045–059°), NNW (326–342°) and a WNW (271–286°). Sedimentologic and diagenetic characteristics of seven sandstone lithofacies control the fracture development and distribution in the group. Key sedimentologic and diagenetic influences on fracture distribution include bed thickness, stratigraphic architecture, the degree of cementation and the type of cement. From these sedimentologic controls on the character of natural fractures, lithofacies can potentially predict fracture distribution within the Mesaverde Group based on environments of deposition. The presence of NW-trending discontinuous sandstone reservoirs deposited in meandering fluvial environments that are highly fractured by a pervasive WNW-striking fracture set helps to explain fairways of prolific natural gas production within the basin.
Sills as fractured hydrocarbon reservoirs: examples and models
Authors: Gudmundsson Agust , Løtveit Ingrid F.
Published: September 2012

Sills are common in sedimentary basins and, through thermal effects, may contribute significantly to the transformation of organic material into oil and gas. In addition, many sills act as hydrocarbon reservoirs, either as seals or as fractured reservoirs themselves. The seals are related to glassy margins and/or low permeable metamorphosed host rocks at the contacts between the sills and their host rocks. Reservoir formation may then be encouraged at sill-fault or sill-dyke contacts, provided the dykes/faults have low permeabilities. If the seal at the lower margin of a sill is ruptured (because of changes in tectonic loading) while the seal at the upper margin is maintained, the sill may itself act as a fractured hydrocarbon reservoir. Major sills in sedimentary basins are mostly
c.
15–150 m thick and are mostly fed by (much thinner) dykes. Deflection of dykes into sills is primarily due to three related factors: (1) opening of contacts ahead of the feeder dyke (the ‘Cook–Gordon debonding’); (2) dykes meeting layers with local stresses unfavourable to dykes but favourable to sills (‘stress barriers’); and (3) abrupt increase in Young's modulus (‘elastic mismatch’) across a contact. Theoretical models predict common lateral dimension/maximum thickness (aspect) ratios of sills between 150 and 500, in agreement with actual measurements of sill dimensions. Many thick sills worldwide are currently exploited as hydrocarbon reservoirs.
Micro perceptual human computation for visual tasks
Authors: Gingold Yotam , Shamir Ariel , Cohen-Or Daniel
Published: September 2012

Human Computation (HC) utilizes humans to solve problems or carry out tasks that are hard for pure computational algorithms. Many graphics and vision problems have such tasks. Previous HC approaches mainly focus on generating data in batch, to gather benchmarks, or perform surveys demanding nontrivial interactions. We advocate a tighter integration of human computation into online, interactive algorithms. We aim to distill the differences between humans and computers and maximize the advantages of both in one algorithm. Our key idea is to decompose such a problem into a massive number of very simple, carefully designed, human
micro-tasks
that are based on
perception
, and whose answers can be combined algorithmically to solve the original problem. Our approach is inspired by previous work on micro-tasks and perception experiments. We present three specific examples for the design of micro perceptual human computation algorithms to extract depth layers and image normals from a single photograph, and to augment an image with high-level semantic information such as symmetry.
Updated sparse cholesky factors for corotational elastodynamics
Authors: Hecht Florian , Lee Yeon Jin , Shewchuk Jonathan R. , O'Brien James F.
Published: September 2012

We present
warp-canceling corotation
, a nonlinear finite element formulation for elastodynamic simulation that achieves fast performance by making only partial or delayed changes to the simulation's linearized system matrices. Coupled with an algorithm for incremental updates to a sparse Cholesky factorization, the method realizes the stability and scalability of a sparse direct method without the need for expensive refactorization at each time step. This finite element formulation combines the widely used corotational method with stiffness warping so that changes in the per-element rotations are initially approximated by inexpensive per-node rotations. When the errors of this approximation grow too large, the per-element rotations are selectively corrected by updating parts of the matrix chosen according to locally measured errors. These changes to the system matrix are propagated to its Cholesky factor by incremental updates that are much faster than refactoring the matrix from scratch. A nested dissection ordering of the system matrix gives rise to a hierarchical factorization in which changes to the system matrix cause limited, well-structured changes to the Cholesky factor. We show examples of simulations that demonstrate that the proposed formulation produces results that are visually comparable to those produced by a standard corotational formulation. Because our method requires computing only partial updates of the Cholesky factor, it is substantially faster than full refactorization and outperforms widely used iterative methods such as preconditioned conjugate gradients. Our method supports a controlled trade-off between accuracy and speed, and unlike most iterative methods its performance does not slow for stiffer materials but rather it actually improves.
Sensor network localization by eigenvector synchronization over the euclidean group
Authors: Cucuringu Mihai , Lipman Yaron , Singer Amit
Published: September 2012

We present a new approach to localization of sensors from noisy measurements of a subset of their Euclidean distances. Our algorithm starts by finding, embedding, and aligning uniquely realizable subsets of neighboring sensors called patches. In the noise-free case, each patch agrees with its global positioning up to an unknown rigid motion of translation, rotation, and possibly reflection. The reflections and rotations are estimated using the recently developed eigenvector synchronization algorithm, while the translations are estimated by solving an overdetermined linear system. The algorithm is scalable as the number of nodes increases and can be implemented in a distributed fashion. Extensive numerical experiments show that it compares favorably to other existing algorithms in terms of robustness to noise, sparse connectivity, and running time. While our approach is applicable to higher dimensions, in the current article, we focus on the two-dimensional case.
Sensor network data fault detection with maximum a posteriori selection and bayesian modeling
Authors: Ni Kevin , Pottie Greg
Published: September 2012

Current sensor networks experience many faults that hamper the ability of scientists to draw significant inferences. We develop a method to systematically identify when these faults occur so that proper corrective action can be taken. We propose an adaptable modular framework that can utilize different modeling methods and approaches to identifying trustworthy sensors. We focus on using hierarchical Bayesian space-time (HBST) modeling to model the phenomenon of interest, and use maximum a posteriors selection to identify a set of trustworthy sensors. Compared to an analogous linear autoregressive system, we achieve excellent fault detection when the HBST model accurately represents the phenomenon.
A case for hierarchical routing in low-power wireless embedded networks
Authors: Iwanicki Konrad , Van Steen Maarten
Published: September 2012

Hierarchical routing has often been mentioned as an appealing point-to-point routing technique for wireless sensor networks (sensornets). While there is a volume of analytical and high-level simulation results demonstrating its merits, there has been little work evaluating it in actual sensornet settings. This article bridges the gap between theory and practice.

Having analyzed a number of proposed hierarchical routing protocols, we have developed a framework that captures the common characteristics of the protocols and identifies design points at which the protocols differ. We use a sensornet implementation of the framework in TOSSIM and on a 60-node testbed to study various trade-offs that hierarchical routing introduces, as well as to compare the performance of hierarchical routing with the performance of other routing techniques, namely shortest-path routing, compact routing, and beacon vector routing. The results show that hierarchical routing is a compelling routing technique also in practice. In particular, despite only logarithmic routing state, it can offer small routing stretch: an average of ∼ 1.25 and a 99th percentile of 2. It can also be robust, minimizing the maintenance traffic or the latency of reacting to changes in the network. Moreover, the trade-offs offered by hierarchical routing are attractive for many sensornet applications when compared to the other routing techniques. For example, in terms of routing state, hierarchical routing can offer scalability at least an order of magnitude better than compact routing, and at the same time, in terms of routing stretch, its performance is within 10--15% of that of compact routing; in addition, this performance can further be tuned to a particular application. Finally, we also identify a number of practical issues and limitations of which we believe sensornet developers adopting hierarchical routing should be aware.
Comparison of methods for language-dependent and language-independent query-by-example spoken term detection
Authors: Tejedor Javier , Fapšo Michal , Szöke Igor , Černocký Jan “Honza” , Grézl František
Published: September 2012

This article investigates query-by-example (QbE) spoken term detection (STD), in which the query is not entered as text, but selected in speech data or spoken. Two feature extractors based on neural networks (NN) are introduced: the first producing phone-state posteriors and the second making use of a compressive NN layer. They are combined with three different QbE detectors: while the Gaussian mixture model/hidden Markov model (GMM/HMM) and dynamic time warping (DTW) both work on continuous feature vectors, the third one, based on weighted finite-state transducers (WFST), processes phone lattices. QbE STD is compared to two standard STD systems with text queries: acoustic keyword spotting and WFST-based search of phone strings in phone lattices. The results are reported on four languages (Czech, English, Hungarian, and Levantine Arabic) using standard metrics: equal error rate (EER) and two versions of popular figure-of-merit (FOM). Language-dependent and language-independent cases are investigated; the latter being particularly interesting for scenarios lacking standard resources to train speech recognition systems. While the DTW and GMM/HMM approaches produce the best results for a language-dependent setup depending on the target language, the GMM/HMM approach performs the best dealing with a language-independent setup. As far as WFSTs are concerned, they are promising as they allow for indexing and fast search.
Analyzing and Visualizing Jump Performance Using Wireless Body Sensors
Authors: Pradhan Gaurav N. , Prabhakaran B.
Published: September 2012

Advancement in technology has led to the deployment of body sensor networks (BSN) to monitor and sense human activity in pervasive environments. Using multiple wireless on-body systems, such as physiological data monitoring and motion capture systems, body sensor network data consists of heterogeneous physiologic and motoric streams that form a multidimensional framework. In this article, we analyze such high-dimensional body sensor network data by proposing an efficient, multidimensional factor analysis technique for quantifying human performance and, at the same time, providing visualization for performances of participants in a low-dimensional space for easier interpretation.
Quantitative Analysis of Systems Using Game-Theoretic Learning
Authors: Seshia Sanjit A. , Rakhlin Alexander
Published: September 2012

The analysis of quantitative properties, such as timing and power, is central to the design of reliable embedded software and systems. However, the verification of such properties on a program is made difficult by their heavy dependence on the program’s environment, such as the processor it runs on. Modeling the environment by hand can be tedious, error prone, and time consuming. In this article, we present a new game-theoretic approach to analyzing quantitative properties that is based on performing systematic measurements to automatically learn a model of the environment. We model the problem as a game between our algorithm (player) and the environment of the program (adversary) in which the player seeks to accurately predict the property of interest, while the adversary sets environment states and parameters. To solve this problem, we employ a randomized strategy that repeatedly tests the program along a linear-sized set of program paths called basis paths, using the resulting measurements to infer a weighted-graph model of the environment from which quantitative properties can be predicted. Test cases are automatically generated using satisfiability modulo theories (SMT) solving. We prove that our algorithm can, under certain assumptions and with arbitrarily high probability, accurately predict properties such as worst-case execution time or estimate the distribution of execution times. Experimental results for execution time analysis demonstrate that our approach is efficient, accurate, and highly portable.
Time-Triggered Implementations of Dynamic Controllers
Authors: Nghiem Truong , Pappas George J. , Alur Rajeev , Girard Antoine
Published: September 2012

Bridging the gap between model-based design and platform-based implementation is one of the critical challenges for embedded software systems. In the context of embedded control systems that interact with an environment, a variety of errors due to quantization, delays, and scheduling policies may generate executable code that does not faithfully implement the model-based design. In this article, we show that the performance gap between the model-level semantics of linear dynamic controllers, for example, the proportional-integral-derivative (PID) controllers and their implementation-level semantics, can be rigorously quantified if the controller implementation is executed on a predictable time-triggered architecture. Our technical approach uses lifting techniques for periodic time-varying linear systems in order to compute the exact error between the model semantics and the execution semantics. Explicitly computing the impact of the implementation on overall system performance allows us to compare and partially order different implementations with various scheduling or timing characteristics.
Graphical passwords
Authors: Biddle Robert , Chiasson Sonia , Van Oorschot P.C.
Published: September 2012

Starting around 1999, a great many graphical password schemes have been proposed as alternatives to text-based password authentication. We provide a comprehensive overview of published research in the area, covering both usability and security aspects as well as system evaluation. The article first catalogues existing approaches, highlighting novel features of selected schemes and identifying key usability or security advantages. We then review usability requirements for knowledge-based authentication as they apply to graphical passwords, identify security threats that such systems must address and review known attacks, discuss methodological issues related to empirical evaluation, and identify areas for further research and improved methodology.
Survey of state melding in virtual worlds
Authors: Liu Huaiyu , Bowman Mic , Chang Francis
Published: September 2012

The fundamental goal of virtual worlds is to provide users with the illusion that they are all seeing and interacting with each other in a consistent world. State melding is the core of creating this illusion of a shared reality. It includes two major parts: consistency maintenance and state update dissemination. Well-designed state melding technologies are also critical for developing a virtual world that can scale to a large number of concurrent users and provide satisfying user experiences. In this article, we present a taxonomy of consistency models and categorization of state update dissemination technologies for virtual worlds. To connect theories and practices, we then apply the taxonomy to case study several state-of-the-art virtual worlds. We also discuss challenges and promising solutions of state melding in large-scale virtual worlds. This survey aims to provide a thorough understanding of existing approaches and their strength and limitations and to assist in developing solutions to improve scalability and performance of virtual worlds.
A review of error estimation in adaptive quadrature
Authors: Gonnet Pedro
Published: September 2012

The most critical component of any adaptive numerical quadrature routine is the estimation of the integration error. Since the publication of the first algorithms in the 1960s, many error estimation schemes have been presented, evaluated, and discussed. This article presents a review of existing error estimation techniques and discusses their differences and their common features. Some common shortcomings of these algorithms are discussed, and a new general error estimation technique is presented.
Assistive tagging
Authors: Wang Meng , Ni Bingbing , Hua Xian-Sheng , Chua Tat-Seng
Published: September 2012

Along with the explosive growth of multimedia data, automatic multimedia tagging has attracted great interest of various research communities, such as computer vision, multimedia, and information retrieval. However, despite the great progress achieved in the past two decades, automatic tagging technologies still can hardly achieve satisfactory performance on real-world multimedia data that vary widely in genre, quality, and content. Meanwhile, the power of human intelligence has been fully demonstrated in the Web 2.0 era. If well motivated, Internet users are able to tag a large amount of multimedia data. Therefore, a set of new techniques has been developed by combining humans and computers for more accurate and efficient multimedia tagging, such as batch tagging, active tagging, tag recommendation, and tag refinement. These techniques are able to accomplish multimedia tagging by jointly exploring humans and computers in different ways. This article refers to them collectively as
assistive tagging
and conducts a comprehensive survey of existing research efforts on this theme. We first introduce the status of automatic tagging and manual tagging and then state why assistive tagging can be a good solution. We categorize existing assistive tagging techniques into three paradigms: (1) tagging with data selection & organization; (2) tag recommendation; and (3) tag processing. We introduce the research efforts on each paradigm and summarize the methodologies. We also provide a discussion on several future trends in this research direction.