bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of residual life in flexible pavements
Authors: Livneh Moshe
Published: January 2010

In the field of pavement rehabilitation design, one finds a prominent absence of uniformity in the principles of calculation, a lack of clarity as to the testing methods, and a confusion of basic physical concepts. An example of this situation is the residual life of the pavement structure, which constitutes an important measure in the calculation of pavement bearing capacity. The basic question of how to establish such a parameter in practice is discussed in this paper by examining the relationships between the residual life parameter and the pavement surface state, the pavement structural state, the pavement functional state, and the effects of asphalt fatigue or the total structural deterioration on the residual life-span. Finally, this paper suggests a method for including the residual life parameter within the design process of flexible pavement rehabilitation. Key words: cracking, damages, deflection, permanent deformation, evaluation, fatigue, flexible pavements, overlay, rehabilitation, service level, visual testing.
Estimating design quantiles from scarce data
Authors: Hong Han Ping , Lind Niels C.
Published: January 2010

The statistical data available to determine design parameters are often scarce. Probability-based design requires estimates of quantiles that lie in a tail region of the distribution of the random variables. Common methods of estimation (e.g., the method of moments or maximum likelihood) employ a few well-known fundamental distribution models for which standard procedures are available. Unfortunately, they yield distributions that generally violate a strict combinatorial constraint (the sample rule) that is particularly crucial in the tail regions. This paper presents an alternative method to determine quantiles from a set of independent observations of a random variable. A Lagrange polynomial mapping is used to generalize the fundamental distribution type and to satisfy the sample rule in the relevant tail and at any desired number of sample points. Resampling, of interest when the sample size is very small, is easily incorporated. A formulation to estimate high and low quantiles, based only on three constraints, is given for practical use. The calculations are as simple as those for the common methods or simpler. The method is illustrated for a fundamental distribution of the lognormal type. Results obtained by using the lognormal polynomial method of Lind and the method of Jaeger and Bakht applied to an observed data set and its resampled data set are compared. Key words: design, estimation, extreme, Lagrange polynomial, probability, distribution, quantile, random, resampling, statistics, tail.
Application of inelastic response spectra derived from seismic hazard spectral ordinates for Canada
Authors: Humar J. L. , Rahgozar M. A.
Published: January 2010

The Geological Survey of Canada is currently producing a suite of new hazard maps for Canada. These maps take into account the additional recorded data obtained during the past 13 years, as well as the new geological and tectonic information that has recently become available. They provide elastic spectral acceleration values for a uniform probability of exceedance of 10% in 50 years. A method of using the uniform hazard spectral values to obtain design response spectral curves for different values of ductility is presented here. The method uses two spectral values obtained from the hazard maps, the peak spectral acceleration for the site and the spectral acceleration corresponding to a period of 0.5 s. Empirical expressions are developed to represent the design response spectra. It is shown that by using inelastic spectral accelerations rather than the elastic spectral values in association with a reduction factor, the new method provides a more reliable estimate of the design forces. Key words: uniform hazard spectra; inelastic spectra, seismic design forces, force modification factor, foundation factor, seismic hazard for Canada.
Bridge management by dynamic programming and neural networks
Authors: Razaqpur A. G. , Halim A. O. Abd El , Mohamed Hosny A.
Published: January 2010

Bridges and pavements represent the major investment in a highway network. In addition, they are in constant need of maintenance, rehabilitation, and replacement. One of the problems related to highway infrastructure is that the cost of maintaining a network of bridges with an acceptable level-of-service is more than the budgeted funds. For large bridge networks, traditional management practices have become inadequate for dealing with this serious problem. Bridge management systems are a relatively new approach developed to solve the latter problem, following the successful application of similar system concepts to pavement management. Priority setting schemes used in bridge management systems range from subjective basis using engineering judgement to very complex optimization models. However, currently used priority setting schemes do not have the ability to optimize the system benefits in order to get optimal solutions. This paper presents a network optimization model which allocates a limited budget to bridge projects. The objective of the model is to determine the best timing for carrying out these projects and the spending level for each year of the analysis period in order to minimize the losses of the system benefits. A combined dynamic programming and neural network approach was utilized to formulate the model. The bridge problem has two dimensions: the time dimension and the bridge network dimension. The dynamic programming sets its stages in the time dimension, while the neural network handles the network dimension. Key words: bridge management, dynamic programming, neural networks, budget allocation.
La résistance au gel des bétons à haute performance
Authors: Marchand J. , Pigeon M. , Gagné R. , Jacobsen S. , Sellevold E. J.
Published: January 2010

A literature survey of the frost resistance of high-performance concrete (HPC) is presented in this paper. Various aspects of HPC behaviour to frost, such as ice formation, resistance to internal microcracking and scaling, and air entrainment were discussed. The survey clearly indicates that the volume of ice formed in the 0 to −20 °C range is significantly reduced by the low porosity of HPC. This reduction is often accompanied by a significant improvement of the scaling resistance. Some studies even reveal the existence of a critical water/binder ratio below which air entrainment would not be required as a protection against this type of deterioration. However, this critical water/binder ratio would not apply to internal cracking. In many instances, HPC with no air entrainment were resistant to scaling but susceptible to internal microcracking. The behaviour of HPC to frost is discussed from both theoretical and applied points of view. Key words: frost resistance, high-performance concrete, ice formation, internal microcracking, scaling.
Factors influencing changes in modal choice in the Toronto region
Authors: D'abadie Robert , Hutchinson Bruce G.
Published: January 2010

The paper summarizes the changes in modal transport choice behaviour that occurred in the Toronto region between 1986 and 1991. The evidence presented shows that the region has become more dependent on automobile travel, making the sustainable transport targets adopted by Canada even more difficult to achieve. These changes are analyzed in terms of (i) changes in the size of the socio-demographic market segments that influence modal transport choice, (ii) changes in the choice probabilities of these market segments, and (iii) changes in the spatial structure of the Toronto region. The socio-demographic changes during the 1986–1991 period are less favourable to public transport and the probabilities of selecting public transport for the journey to work have decreased substantially for most of the market segments. The paper shows the overwhelming influence of development density on modal transport choice and the beneficial influence of adjacent high density employment and residential densities on the use of nonmotorized travel. The paper argues that the excessive auto-dependency of the Toronto region is likely to change only if high density suburban development forms are created and comprehensive road and parking pricing schemes introduced. Key words: urban transport, transport mode choice, public transport, regional development.
Precision of the air void characteristics measurement by ASTM C 457: results of an interlaboratory test program
Authors: Saucier François , Pleau Richard , Vézina Daniel
Published: January 2010

Since 1993, the Quebec Department of Transportation requires all its concrete suppliers to demonstrate that their concrete satisfies the requirements of the CSA A23.1 standard as regards the maximum spacing factor of the air void system. This new requirement raises questions about the reproducibility of the ASTM C 457 test method. An interlaboratory study was carried out to verify if the variability of the test method is sufficiently low to allow reliable decisions on the acceptance or rejection of in-place hardened concrete. A total of 18 operators from 13 different laboratories microscopically examined the six concrete slabs used for the study. It is concluded that the average reproducibility coefficient of variation is 14.4% for the total air content measurement and 14.2% for the spacing factor measurement. Considering these results, the probability that the measured value of the spacing factor exceeds the mandatory limit of 230 μm on a concrete production containing an air void system with a spacing factor of 170 μm (the target value proposed in the CSA A23.1 M-94 standard) is less than 0.7% (a probability of error of about 1%, 5%, or 10% is typical of most quality control test methods). Key words: concrete, air content, air void measurement, spacing factor, ASTM C 457 standard, interlaboratory study, freeze–thaw durability.
Auscultation d'une culée du pont de Portneuf à l'aide d'une inclusion de béton instrumentée (CIUS)
Authors: Bois Axel-Pierre , Lachemi Mohamed , Ballivy Gérard
Published: January 2010

The Portneuf Bridge, built in 1992, is the first air-entrained high-performance concrete bridge in North America. To understand its short and long term behaviour, an auscultation program has been set. Hence, a cylindrical concrete inclusion of the Université de Sherbrooke was installed in one of the abutments of the bridge. The aim of this study is to present the first results thus acquired. The analysis of the results allowed to calculate the coefficient of thermal expansion of the concrete and to assess deformation variations due to shrinkage and creep and the effects of rebar–concrete interaction in the upper abutment region. Moreover, the presence of thermal gradients, which creates nonisotropic deformations, has been established. Key words: high-performance concrete, deformations, thermal gradients, instrumentation, bridge, monitoring. [Journal translation]
Nonlinearity aspects of edge of pavement on superelevation runoffs
Authors: Polus Abishai , Reshetnik Israel
Published: January 2010

The purpose of this paper is to evaluate the differences between two design alternatives for the pavement edge along the superelevation runoff. The highway literature usually recommends to design the edge as a combination of straight lines, i.e., linear edge design and nonlinear change of superelevation. It is possible, however, to construct another method by which the superelevation increases linearly within the pavement along the runoff. This paper analyzes the two design alternatives and examines the differences between the two methods. It was shown that on a spiralled highway, a linear change of the superelevation is more suitable for the motion equation on the spiral. This provides a more natural transition and an increase in driver's comfort. When a spiral does not exist, the linear change of the pavement edge, which causes a nonlinear change in the superelevation rate, leads to a reduced side friction at the critical section where the superelevation was not fully developed. It is shown that the difference between the two methods is relatively small and therefore for reasons of practicality, the recommendation is to adapt the linear edge of pavement design. Key words: highway, superelevation, edge of pavement, runoff, spiral.
Spatial characterization of drought events using synthetic hydrology
Authors: Burn Donald H. , DeWit William J.
Published: January 2010

This paper describes an approach to spatial drought analysis based on multi-site streamflow synthesis. The approach developed can be used to assist with the quantification of the return period for the drought of record and can also be used to facilitate the identification of daesign drought events of a specified return period. The approach was applied to the Nelson–Churchill River basin in Manitoba, Canada. For this system, the impacts of droughts on power generation were investigated in addition to a determination of the return period for the drought of record. Key words: droughts, streamflow generation, frequency analysis, hydroelectric power.
Winter streamflow variability in two groundwater-fed sub-Arctic rivers, Yukon Territory, Canada
Authors: Hamilton A. S. , Moore R. D.
Published: January 2010

Frequent discharge measurements were made during the winter of 1994–1995 in two groundwater-fed streams near Whitehorse, Yukon Territory, to evaluate the nature and causes of winter discharge variability in sub-Arctic rivers. Observations were also made of near-stream hydraulic head, snowmelt percolation, and water quality. A linear reservoir model provided a poor fit to the streamflow recessions at both rivers, whereas three relatively complex models provided good fits to the data used for calibration. A pronounced discharge depression occurred at M'Clintock River associated with an increase in stage at freeze-up. The volume of water represented by the depression was about three times the maximum amount that could be accounted for by channel storage. This discrepancy could have been caused by stream–aquifer interactions. Piezometric observations were consistent with a reversal of hydraulic gradient across the stream bed, which would block or reduce groundwater inflow, as well as cause water to go into bank storage. A sustained discharge depression did not occur at Ibex River, probably because the volume of channel storage is small with respect to discharge and could be satisfied over the period of freeze-up without measurable deviation from the recession trend, and because the near-stream hydraulic gradients were strong enough not to be influenced by stage increases. Discharge at Ibex River was uncorrelated with air temperature. At M'Clintock River, residuals from the layered linear reservoir model appeared to be weakly correlated with air temperature. Key words: baseflow, river ice, winter, Yukon Territory, streamflow, stream–aquifer interactions.
Les effets des caractéristiques du réseau de bulles d'air, du type de mûrissement, du truellage de surface et de la fumée de silice sur la résistance à l'écaillage d'un béton à haute performance
Authors: Gagné Richard , Latreille Yvon , Marchand Jacques
Published: January 2010

In Canada, high-performance concretes (HPCs) are increasingly used in construction and repair, particularly for its durability, which is distinctly superior compared with ordinary concrete. The current tendency is to provide for a spacing factor of air bubbles lower than 230 μm in all HPCs that are subjected to freeze–thaw cycles. This choice is basically the outcome of an ongoing controversy as to the necessity of providing a good network of entrained air bubbles to protect HPCs against freeze–thaw cycles. In the future, the optimal use of HPC will depend, among other factors, on a better understanding of minimal requirements regarding the characteristics of air voids to ensure a good behavior of HPCs under freeze–thaw cycles. The results of the investigation reported herein show that a spacing factor lower than approximately 500 μm can be sufficient to ensure a good resistance of HPCs to scaling. It is also shown that surface trawling, slump, and set-retarding agents have only secondary effects on the scaling resistance of HPCs. Silica fume and membrane curing have allowed to improve significantly the scaling resistance of the HPCs under investigation. Key words: high-performance concrete, durability, scaling, set-retarding agent, silica fume, surface finishing, curing, pumping, entrained air, spacing factor.
Operation strategies for psychrophilic anaerobic digestion of swine manure slurry in sequencing batch reactors
Authors: Massé D. I. , Patni N. K. , Droste R. L. , Kennedy K. J.
Published: January 2010

The objective of this study was to evaluate the performance of psychrophilic anaerobic digestion in sequencing batch reactors (SBRs) under operating strategies that would optimize process performance and stability while minimizing the interference of the bioreactor operation with regular farm activities. Process performance was evaluated on (i) reduction in pollution potential; (ii) energy recovery; and (iii) odour reduction. Experiments were carried out in twelve 40-L SBRs. Experimental results indicated that psychrophilic anaerobic digestion of swine manure slurry at 20 °C in an intermittently fed SBR (i) reduced the pollution potential of swine manure slurry by removing 84 – 93% of the soluble chemical oxygen demand and 41 – 83% of total chemical oxygen demand; (ii) produced biogas at rates exceeding 0.48 L of CH4 per gram of volatile solids fed; and (iii) successfully reduced odours. Other findings were that (i) for all experimental runs, psychrophilic anaerobic digestion of swine manure slurry in SBRs was very stable; (ii) the process generally performed well without external mixing; and (iii) intermittent feeding of once or three times a week did not affect process stability and performance. As a result, this process requires little energy input and most of the energy produced will be available for farm use. Since this process is very stable, process feeding could be integrated with the routine operation of manure removal from the barn, thereby minimizing interference with other farm operations. Key words: anaerobic, anaerobic treatment, psychrophilic, animal manure, methane production, process control, manure treatment.
Shear lag in slotted HSS tension members
Authors: Korol R. M.
Published: January 2010

A research program was undertaken to study the shear-lag phenomenon for slotted hollow structural section (HSS) tension members having gusset plates welded at the ends, a commonly employed detail in braced frame construction. The purpose of this study was to establish whether the shear-lag reduction factor indeed involves only the weld length to weld distance ratio, or if other parameters also influence connection strength and behaviour. Key words: shear lag, slotted members, reduction factor, design, experiments, hollow structural sections.
SUBCONSCIOUS EFFECT ON PEDESTRIAN COUNTER FLOW IN A MODIFIED LATTICE GAS MODEL WITH THE VARIABLE TRANSITION PROBABILITY
Authors: KUANG HUA , TAO SONG , DAI SHIQIANG , LI XINGLI
Published: January 2010

Pedestrian behavioral modeling is an important topic to reproduce rich pedestrian dynamics phenomena. In this paper, a modified lattice gas model is proposed to simulate pedestrian counter flow under periodic boundary conditions by considering the variable transition probability, which can quantitatively describe complex human subconscious behaviors and distinguish the individual and common characteristics of pedestrians. Four types of walkers are involved in the model, and their dynamical characteristics are discussed in some complex situations. The simulation results show that the presented model can reproduce some essential features of pedestrian counter flows, such as the lane formation, segregation effect and phase separation. For the mixed pedestrian flows, the comparison between the subconscious behaviors of obeying the traffic rules and those of breaking the traffic rules indicates that the former could effectively reduce the occurrence of jam cluster. In addition, it is found that with increase of the strength of drift D1, the jam transition threshold decreases. Finally, the simulation results are compared with our previous study (see Ref. 32). It is shown that the mean velocity and the mean flow are always larger at the free moving phase, and the underlying mechanism is discussed in detail.
A FUZZY NEURAL NETWORK FOR THE ACTIVE VIBRATION CONTROL OF A CENTRIFUGAL PENDULUM VIBRATION ABSORBER
Authors: LIANG CHI-HSIUNG , TUNG PI-CHENG
Published: January 2010

In this study, we develop a fuzzy back-propagation (BP) neural network controller for active vibration control of a centrifugal pendulum vibration absorber (CPVA). The fuzzy BP neural network controller systems can be viewed as a conventional fuzzy algorithm for coarse tuning. The BP algorithm can also be applied for fine tuning, in this case to regulate the anti-resonance frequency in an active pendulum vibration absorber (APVA), by suppressing vibration of the carrier. The dynamic model of the APVA was developed and simulated using MATLAB. In the simulation results, when the frequency of the disturbance changes, the outputs of the fuzzy BP neural network controller are used to determine an appropriate value for the torque of the active pendulum such that the vibration amplitude of the carrier is minimized. A comparison of the carrier vibration results for the CPVA, the fuzzy algorithm and the fuzzy BP algorithm is performed. The simulation results demonstrate the effectiveness of the proposed fuzzy BP neural network APVA for reducing the carrier vibrations.
GEOMETRIC STRUCTURAL ASPECTS OF PROTEINS AND NEWCOMB–BENFORD LAW
Authors: MORET M. A. , de SENNA V. , SANTANA M. C. , ZEBENDE G. F.
Published: January 2010

The major factor that drives a protein toward collapse and folding is the hydrophobic effect. At the folding process a hydrophobic core is shielded by the solvent-accessible surface area of the protein. We study the behavior of the numbers in 5526 protein structures present in the Brookhaven Protein Data Bank. The first digit of mass, volume, average radius and solvent-accessible surface area are measured independently and we observe that most of these geometric observables obey the Newcomb–Benford law. That is volume, mass and average radius obey the Newcomb–Benford law. Nevertheless, the digits of the solvent-accessible surface area do not agree with the Newcomb–Benford law. The present findings indicate that the hydrophobic effect is responsible for the anomalous first digit behavior of solvent-accessible surface areas.
TOTALLY ASYMMETRIC EXCLUSION PROCESSES ON LATTICES WITH A BRANCHING POINT
Authors: WANG XIONG , JIANG RUI , HU MAO-BIN , NISHINARI KATSUHIRO , WU QING-SONG
Published: January 2010

We study totally asymmetric simple exclusion process (TASEP) where particles move on a single-chain lattice which diverges into two parallel lattice branches. At the branching point, the particles move to one of the two branches with equal rate r/2. The phase diagram and density profiles are investigated by using mean-field approximation and Monte Carlo simulations. It is found that the phase diagram can be classified into three regions at any value of r. However, a threshold [Formula: see text] is identified. In cases of r > rc and r < rc, the phase diagram exhibits qualitatively different phases. The analytical results are in good agreement with the results of Monte Carlo simulations.
OPINION DYNAMICS IN POPULATIONS WITH IMPLICIT COMMUNITY STRUCTURE
Authors: SI XIAMENG , LIU YUN , ZHANG ZHENJIANG
Published: January 2010

Web encounter facilitate contacts between people from different communities outside space and time. Implicit Community Structure is exhibited because of highly connected links within community and sparse encounters between communities. Considering the imperceptible influence of encounter on opinions, Sznajd updating rules are used to mimic people's behaviors after encountering a stranger in another community. We introduce a model for opinion evolution, in which the interconnectivity between different communities is represented as encounter frequency, and leadership is introduced to control the strength of community's opinion guide. In this scenario, the effects of Implicit Community Structure of contact network on opinion evolution, for asymmetric and random initial distribution but with heterogeneous opinion guide, are investigated respectively. It is shown that large encounter frequency favors consensus of the whole populations and successful opinion spreading, which is qualitatively agree with the results observed in Majority model defined on substrates with predefined community structure.
ACHIEVING ENERGY-EFFICIENT BIPEDAL WALKING TRAJECTORY THROUGH GA-BASED OPTIMIZATION OF KEY PARAMETERS
Authors: DAU VAN-HUAN , CHEW CHEE-MENG , POO AUN-NEOW
Published: January 2010

This paper proposes a method of energy-efficient trajectory planning for bipedal walking robots. In this study, we plan hip and foot trajectories in Cartesian space using polynomial interpolation. The seven key parameters which define the hip and foot trajectories are optimized by genetic algorithm (GA). Since the hip trajectory is crucial to the stability and walking performance of bipedal robot, we introduce a way to increase hip trajectory's variation by extending the order of the interpolated polynomial and using a set of key parameters. To ensure stable walking motion, we employ the zero-moment-point (ZMP) as the stability criterion. The effectiveness of our proposed method is verified by two simulation examples (flat terrain walking and slope walking) of a humanoid robot named NUSBIP-II.
ESTIMATES AND COMPUTATIONS IN RABINOWITZ–FLOER HOMOLOGY
Authors: ABBONDANDOLO ALBERTO , SCHWARZ MATTHIAS
Published: January 2010

The Rabinowitz–Floer homology of a Liouville domain W is the Floer homology of the Rabinowitz free period Hamiltonian action functional associated to a Hamiltonian whose zero energy level is the boundary of W. This invariant has been introduced by K. Cieliebak and U. Frauenfelder and has already found several applications in symplectic topology and in Hamiltonian dynamics. Together with A. Oancea, the same authors have recently computed the Rabinowitz–Floer homology of the cotangent disk bundle D* M of a closed Riemannian manifold M, by means of an exact sequence relating the Rabinowitz–Floer homology of D* M with its symplectic homology and cohomology. The first aim of this paper is to present a chain level construction of this exact sequence. In fact, we show that this sequence is the long homology sequence induced by a short exact sequence of chain complexes, which involves the Morse chain complex and the Morse differential complex of the energy functional for closed geodesics on M. These chain maps are defined by considering spaces of solutions of the Rabinowitz–Floer equation on half-cylinders, with suitable boundary conditions which couple them with the negative gradient flow of the geodesic energy functional. The second aim is to generalize this construction to the case of a fiberwise uniformly convex compact subset W of T* M whose interior part contains a Lagrangian graph. Equivalently, W is the energy sublevel associated to an arbitrary Tonelli Lagrangian L on TM and to any energy level which is larger than the strict Mañé critical value of L. In this case, the energy functional for closed geodesics is replaced by the free period Lagrangian action functional associated to a suitable calibration of L. An important issue in our analysis is to extend the uniform estimates for the solutions of the Rabinowitz–Floer equation — both on cylinders and on half-cylinders — to Hamiltonians which have quadratic growth in the momenta. These uniform estimates are obtained by the Aleksandrov integral version of the maximum principle. In the case of half-cylinders, they are obtained by an Aleksandrov-type maximum principle with Neumann conditions on part of the boundary.
TIMELINESReflections on the future of iSchools from a dean inspired by some junior faculty
Authors: Pollack Martha E.
Published: January 2010

This article, by Martha Pollack, Dean of the School of information at the University of Michigan, completes a year in which five of the six Timelines columns have dealt with prospects for research on Information as well as aspects of its history. This is an exciting time for many elements of HCI, including Design, the input and display device renaissance, a flowering of domain-specific HCI-yet this period may be most remembered for its embrace of Information.---Jonathan Grudin
Catching elephants with mice
Authors: Gandhi Sorabh , Suri Subhash , Welzl Emo
Published: January 2010

We propose a scalably efficient scheme for detecting large-scale physically correlated events in sensor networks. Specifically, we show that in a network of
n
sensors arbitrarily distributed in the plane, a sample of
O
(1/ϵ log 1/ϵ) sensor nodes (
mice
) is sufficient to catch any, and
only those
, events that affect Ω (ϵ
n
) nodes (
elephants
), for any 0 < ϵ < 1, as long as the
geometry
of the event has a bounded Vapnik-Chervonenkis (VC) dimension. In fact, the scheme is provably able to estimate the size of an event within the approximation error of ±ϵ
n
/4, which can be improved further at the expense of more mice. The detection algorithm itself requires knowledge of the event geometry (e.g., circle, ellipse, or rectangle) for the sake of computational efficiency, but the combinatorial bound on the sample size (set of mice) depends only on the VC, dimension of the event class and not the precise shape geometry.

While nearly optimal in theory, due to implicit constant factors, these “scale-free” bounds still prove too large in practice if applied blindly. We therefore propose heuristic improvements and perform empirical parameter tuning to counter the pessimism inherent in these theoretical estimates. Using a variety of data distributions and event geometries, we show through simulations that the final scheme is eminently scalable and practical, say, for
n
≥ 1000. The overall simplicity and generality of our technique suggests that it is well suited for a wide class of sensornet applications, including monitoring of physical environments, network anomalies, network security, or any abstract binary event that affects a significant number of nodes in the network.
Directed broadcast with overhearing for sensor networks
Authors: Jurdak Raja , Ruzzelli Antonio G. , O'hare Gregory M. P. , Higgs Russell
Published: January 2010

The efficient management of scarce network resources, including energy and bandwidth, represents a central challenge for wireless sensor networks. The current trend in resource management relies on the introduction of control mechanisms, such as control message exchanges, node-specific addressing, and storage of partial network state information. These mechanisms typically incur communication and processing overhead that does not scale well for larger or denser networks. Instead of introducing control mechanisms for network resource management, this article proposes and evaluates a Directed Broadcast with Overhearing (DBO) approach for sensor networks that combines directed broadcast at the network layer with CSMA and packet overhearing at the MAC layer. Through avoidance of control messaging and exchange of network state information, DBO trades off limited packet duplication overhead for control messaging overhead. This article introduces an analytical model that provides the basis for DBO evaluation and for analysis of the approach's transient packet retransmissions, route convergence, and energy consumption in the average and worst cases. We also present the model implementation details and the simulation experiments that explore the suitability of DBO for networks of different sizes with three different radio models that vary the width of grey regions, and we compare DBO's energy consumption against conventional unicast beacon-based and snooping-based routing protocols. The results indicate that that DBO's route convergence requires an average of five hops for ideal radio reception, seven hops for narrow grey regions, and twelve hops for wide grey regions. These results confirm that DBO shifts energy consumption from critical nodes near the base station to nodes near the source. The overall energy consumption of limited packet duplication overhead with DBO compared to unicast routing shrinks for medium- to large-size networks, rendering it more favorable than conventional communication approaches for large and dense sensor networks.
ShortPK
Authors: Wang Ronghua , Du Wenliang , Liu Xiaogang , Ning Peng
Published: January 2010

Broadcast authentication is an important functionality in sensor networks. Energy constraints on sensor nodes and the real-time nature of the broadcasts render many of the existing solutions impractical: previous works focusing primarily on symmetric key schemes have difficulties in achieving real-time authentication. Public Key Cryptography (PKC), however, can satisfy the real-time requirements, and recent trends indicate that public key is becoming feasible for sensor networks.

However, PKC operations are still expensive computations. It is impractical to use PKC in the conventional ways for broadcast authentication in sensor networks. To reduce costs, we propose
ShortPK
, an efficient Short-term Public Key broadcast authentication scheme. The basic idea is to use short-length public/private keys, but limit their lifetime to only a short period of time. To cover a long period of time, we need to use many public/private key pairs; distributing these public keys to sensors is a challenging problem. We describe a progressive key distribution scheme that is secure, efficient, and packet-loss resilient. We compare our scheme with the traditional 160-bit ECC public key schemes, and show that our scheme can achieve a significant improvement on energy consumption.
Learning SQL Programming with Interactive Tools
Authors: Brusilovsky Peter , Sosnovsky Sergey , Yudelson Michael V. , Lee Danielle H. , Zadorozhny Vladimir , Zhou Xin
Published: January 2010

Rich, interactive eLearning tools receive a lot of attention nowadays from both practitioners and researchers. However, broader dissemination of these tools is hindered by the technical difficulties of their integration into existing platforms. This article explores the technical and conceptual problems of using several interactive educational tools in the context of a single course. It presents an integrated Exploratorium for database courses, an experimental platform, which provides personalized access to several types of interactive learning activities. Several classroom studies of the Exploratorium have demonstrated its value in both the integration of several tools and the provision of personalized access.
Visualization Tools for Teaching Computer Security
Authors: Yuan Xiaohong , Vega Percy , Qadah Yaseen , Archer Ricky , Yu Huiming , Xu Jinsheng
Published: January 2010

Using animated visualization tools has been an important teaching approach in computer science education. We have developed three visualization and animation tools that demonstrate various information security concepts and actively engage learners. The information security concepts illustrated include: packet sniffer and related computer network concepts, the Kerberos authentication architecture, and wireless network attacks. These tools are implemented using Macromedia Flash MX Professional Edition. The animations can run from a Web page as Flash Applets or as standalone applications. These visualization tools are intended to be used in undergraduate level computer network and security courses. They can be used as classroom instructor demos, student exercises, or Web-based student learning resources. These tools have been used in various computer network and information security courses at North Carolina A&T State University, and have received positive feedback from the students.
An Agile Constructionist Mentoring Methodology for Software Projects in the High School
Authors: Meerbaum--Salant Orni , Hazzan Orit
Published: January 2010

This article describes the construction process and evaluation of the Agile Constructionist Mentoring Methodology (ACMM), a mentoring method for guiding software development projects in the high school. The need for such a methodology has arisen due to the complexity of mentoring software project development in the high school. We introduce the ACMM and suggest a year-long mentoring template that includes the practices required for the actual mentoring process. The evaluation of the ACMM reveals that the methodology addresses each of the challenges teachers cope with during the mentoring process, which were identified in the first phase of the research.
Boids that see
Authors: Silva Alessandro Ribeiro Da , Lages Wallace Santos , Chaimowicz Luiz
Published: January 2010

Behavioral models have been used in the entertainment industry to increase the realism in the simulation of large groups of individuals. Unfortunately, the classical models can be very compute-intensive when very large groups are considered, reducing its applicability in games and other interactive systems. In this article we explore both search space reduction and parallelism to improve the performance of Reynold's
Boids
model. We propose a methodology that considers self-occlusion (visibility culling) to reduce the number of neighbors and we take advantage the parallelism present in common graphics processor units (GPUs) to allow the simulation of very large groups. We performed different GPU implementations (GPGPU and CUDA); the results show that visibility culling allows significant gains in performance without affecting the model's overall behavior.
Evaluation of a pervasive game for domestic energy engagement among teenagers
Authors: Gustafsson Anton , Katzeff Cecilia , Bang Magnus
Published: January 2010

In this article, we present
Power Agent
—a pervasive game designed to encourage teenagers and their families to reduce energy consumption in the home. The ideas behind this mobile phone-based game are twofold; to transform the home environment and its devices into a learning arena for hands-on experience with electricity usage and to promote engagement via a team competition scheme. We report on the game's evaluation with six teenagers and their families who played the game for ten days in two cities in Sweden. Data collection consisted of home energy measurements before, during, and after a game trial, in addition to interviews with participants at the end of the evaluation. The results suggest that the game concept was highly efficient in motivating and engaging the players and their families to change their daily energy-consumption patterns during the game trial. Although the evaluation does not permit any conclusions as to whether the game had any postgame effects on behavior, we can conclude that the pervasive persuasive game approach appears to be highly promising in regard to energy conservation and similar fields or issues.
Neuronal editor agent for scene cutting in game cinematography
Authors: Passos Erick B. , Montenegro Anselmo , Clua Esteban W. G. , Pozzer Cezar , Azevedo Vinicius
Published: January 2010

Cinematography techniques in games aim to provide high-level abstractions for operating a virtual camera on the basis of concepts borrowed from the movie industry, such as scene, shot, and line of action, among others. One typical approach is the development of agents to execute tasks that are similar to their counterparts in a real movie set: director, editor, and cinematographer. However, a game is an interactive application and resembles a live TV show or a live sport transmission, where the actions taken by all the actors are not known previously. In such a scenario, the role of the editor is of great importance, since he or she is the one who ultimately decides what point of view should appear on the screen. In the context of game cinematography, most previous work has proposed ways of mapping scene concepts and automatically controlling the virtual camera, but without paying much attention to the role of an editor agent. Our article demonstrates an intelligent editor agent that uses neuronal network classifiers to decide shot transition and has an intuitive user interface to the learning mechanism.
An extensible framework for interactive facial animation with facial expressions, lip synchronization and eye behavior
Authors: Queiroz Rossana B. , Cohen Marcelo , Musse Soraia R.
Published: January 2010

In this article we describe our approach to generating convincing and empathetic facial animation. Our goal is to develop a robust facial animation platform that is usable and can be easily extended. We also want to facilitate the integration of research in the area and to directly incorporate the characters in interactive applications such as embodied conversational agents and games. We have developed a framework capable of easily animating MPEG-4 parameterized faces through high-level description of facial actions and behaviors. The animations can be generated in real time for interactive applications. We present some case studies that integrate computer vision techniques in order to provide interaction between the user and a character that interacts with different facial actions according to events in the application.
A bidimensional data structure and spatial optimization for supermassive crowd simulation on GPU
Authors: Passos Erick Baptista , Joselli Mark , Zamith Marcelo , Clua Esteban Walter Gonzalez , Montenegro Anselmo , Conci Aura , Feijo Bruno
Published: January 2010

Computing and presenting emergent crowd simulations in real time is a computationally intensive task. This intensity is mostly due to the complexity of the traversal algorithm needed for the interactions of all elements against each other on the basis of a proximity query. By using special data structures such as grids, and due to the parallel nature of graphics hardware, relevant previou work reduced this complexity considerably, making it possible to achieve interactive frame rates. However, existing proposals tend to be heavily bound by the maximum density of such grids, which is usually high, leading to arguably inefficient algorithms. In this article we propose the use of a fine- grained grid and accompanying data manipulation, to lead to scalable algorithmic complexity. We also implement a representative flocking boids case study, from which we ran benchmarks with more than one million simulated and rendered boids at nearly 30fps. We remark that related previous work achieved no more than 15,000 boids with interactive frame rates.
Physical interfaces for tabletop games
Authors: Leitner J. , Haller M. , Yun K. , Woo W. , Sugimoto M. , Inami M. , Cheok A. D. , Been-Lirn H. D.
Published: January 2010

IncreTable
is a mixed-reality tabletop game inspired by
The Incredible Machine
. Users can combine real and virtual game pieces in order to solve puzzles in the game. Game actions include placing virtual domino blocks with digital pens, controlling a virtual car by modifying the virtual terrain through a depth camera interface, and controlling real robots to topple over real and virtual dominoes.
Generalized Probability Functions
Authors: Martinez Alexandre Souto , González Rodrigo Silva , Terçariol César Augusto Sangaletti
Published: January 2010

From the integration of nonsymmetrical hyperboles, a one‐parameter generalization of the logarithmic function is obtained. Inverting this function, one obtains the generalized exponential function. Motivated by the mathematical curiosity, we show that these generalized functions are suitable to generalize some probability density functions (pdfs). A very reliable rank distribution can be conveniently described by the generalized exponential function. Finally, we turn the attention to the generalization of one‐ and two‐tail stretched exponential functions. We obtain, as particular cases, the generalized error function, the Zipf‐Mandelbrot pdf, the generalized Gaussian and Laplace pdf. Their cumulative functions and moments were also obtained analytically.
Exons 19 and 21 of Epidermal Growth Factor Receptor Are Highly Conserved in Squamous Cell Cancer of the Head and Neck
Authors: Carlson Matthew , Wuertz Beverly , Lin Jizhen , Taylor Randy , Ondrey Frank
Published: January 2010

Objective. Epidermal growth factor receptor (EGFR) tyrosine kinase inhibition (TKI) is a promising treatment in upper aerodigestive malignancies. EGFR inhibitors might be more effective in patients whose tumors harbor specific EGFR mutations. The presence of specific EFGR mutations is predictive of over a 75% response rate to TKI therapies as compared to 10% in wild type cases of non-small cell lung cancer. Our objective was to examine whether these mutations might occur in upper aerodigestive cancers.Design. DNA was extracted from 20 head and neck squamous cell tumors and 4 squamous cell carcinoma cell lines and sequenced the receptor using published primer pairs. We then compared the results against published mutations.Results. No exon 19 or 21 mutations were found in any of the 20 tumors and 0 of 4 cell lines. Based on the tumor data we would predict that no greater than 8% of head and neck tumors (CI 97.5%) would be likely to harbor either of these mutations.Conclusions. Our findings are comparable to results recently published of Korean, Austrian, and Spanish patient populations and we conclude that exon 19 and 21 EGFR mutations are not more common in head and neck cancer than in nonsmall-cell carcinoma.
Review on an Advanced High‐Temperature Measurement Technology: The Optical Fiber Thermometry
Authors: Yu Y. B. , Chow W. K.
Published: January 2010

Optical fiber thermometry technology for high‐temperature measurement is briefly reviewed in this paper. The principles, characteristics, recent progresses and advantages of the technology are described. Examples of using the technology are introduced. Many blackbody, infrared, and fluorescence optical thermometers are developed for practical applications.
Application of Variational Iteration Method to Fractional Hyperbolic Partial Differential Equations
Authors: Dal Fadime
Published: January 2010

The solution of the fractional hyperbolic partial differential equation is obtained by means of the variational iteration method. Our numerical results are compared with those obtained by the modified Gauss elimination method. Our results reveal that the technique introduced here is very effective, convenient, and quite accurate to one‐dimensional fractional hyperbolic partial differential equations. Application of variational iteration technique to this problem has shown the rapid convergence of the sequence constructed by this method to the exact solution.
Intravascular Papillary Endothelial Hyperplasia Associated with Venous Pool Arising in the Lower Lip: A Case Report
Authors: Yonezawa Hisanobu , Hiraki Akimitsu , Iyama Ken-ichi , Shinohara Masanori
Published: January 2010

Intravascular papillary endothelial hyperplasia is a benign nonneoplastic vascular lesion that consists of endothelial cells with abundant vascular tissue with papillary proliferation. An adult female had a painless growing dark red nodule on the left side of the lower lip and often touched and gnawed at it for more than 4 years. The lesion was a tender, smooth mass approximately 1 cm in diameter without discoloration reaction. Magnetic resonance imaging of the lesion showed specific findings. She was diagnosed clinically as having mimicked hemangioma, and the lesion was totally excised under local anesthesia. Histopathological examination revealed that papillary proliferated endothelial cells with venous pool, and the lesion was diagnosed as intravascular papillary endothelial hyperplasia associated with venous pool. There has been no recurrence for more than 1 year. Despite the benign nature of this lesion, it could have been mistaken for a malignant tumor because of its clinical course and radiologic findings.