The science papers I've read

Today I read a paper titled “Path lengths, correlations, and centrality in temporal networks”

The abstract is:
In temporal networks, where nodes interact via sequences of temporary events, information or resources can only flow through paths that follow the time-ordering of events

Such temporal paths play a crucial role in dynamic processes

However, since networks have so far been usually considered static or quasi-static, the properties of temporal paths are not yet well understood

Building on a definition and algorithmic implementation of the average temporal distance between nodes, we study temporal paths in empirical networks of human communication and air transport

Although temporal distances correlate with static graph distances, there is a large spread, and nodes that appear close from the static network view may be connected via slow paths or not at all

Differences between static and temporal properties are further highlighted in studies of the temporal closeness centrality

In addition, correlations and heterogeneities in the underlying event sequences affect temporal path lengths, increasing temporal distances in communication networks and decreasing them in the air transport network

Today I read a paper titled “Thinking like Archimedes with a 3D printer”

The abstract is:
We illustrate Archimedes’ method using models produced with 3D printers

This approach allowed us to create physical proofs of results known to Archimedes and illustrate ideas of a mathematician who is known both for his for his mechanical inventions as well as his breakthroughs in geometry and calculus

We use technology from the 21st century to trace intellectual achievements from the 3rd century BC

While we celebrate the 2300th birthday of Archimedes (287-212 BC) in 2013, we also live in an exciting time, where 3D printing is becoming popular and affordable

Today I read a paper titled “A Novel Algorithm for Real-time Procedural Generation of Building Floor Plans”

The abstract is:
Real-time generation of natural-looking floor plans is vital in games with dynamic environments

This paper presents an algorithm to generate suburban house floor plans in real-time

The algorithm is based on the work presented in [1]

However, the corridor placement is redesigned to produce floor plans similar to real houses

Moreover, an optimization stage is added to find a corridor placement with the minimum used space, an approach that is designed to mimic the real-life practices to minimize the wasted spaces in the design

The results show very similar floor plans to the ones designed by an architect

Today I read a paper titled “Logging safely in public spaces using color PINs”

The abstract is:
Nowadays, we are increasingly logging on many different Internet sites to access private data like emails or photos remotely stored in the clouds

This makes us all the more concerned with digital identity theft and passwords being stolen either by key loggers or shoulder-surfing attacks

Quite surprisingly, the current bottleneck of computer security when logging for authentication is the User Interface (UI): How can we enter safely secret passwords when concealed spy cameras or key loggers may be recording the login session? Logging safely requires to design a secure Human Computer Interface (HCI) robust to those attacks

We describe a novel method and system based on entering secret ID passwords by means of associative secret UI passwords that provides zero-knowledge to observers

We demonstrate the principles using a color Personal Identification Numbers (PINs) login system and describes its various extensions

Today I read a paper titled “Finding statistically significant communities in networks”

The abstract is:
Community structure is one of the main structural features of networks, revealing both their internal organization and the similarity of their elementary units

Despite the large variety of methods proposed to detect communities in graphs, there is a big need for multi-purpose techniques, able to handle different types of datasets and the subtleties of community structure

In this paper we present OSLOM (Order Statistics Local Optimization Method), the first method capable to detect clusters in networks accounting for edge directions, edge weights, overlapping communities, hierarchies and community dynamics

It is based on the local optimization of a fitness function expressing the statistical significance of clusters with respect to random fluctuations, which is estimated with tools of Extreme and Order Statistics

OSLOM can be used alone or as a refinement procedure of partitions/covers delivered by other techniques

We have also implemented sequential algorithms combining OSLOM with other fast techniques, so that the community structure of very large networks can be uncovered

Our method has a comparable performance as the best existing algorithms on artificial benchmark graphs

Several applications on real networks are shown as well

OSLOM is implemented in a freely available software (this http URL), and we believe it will be a valuable tool in the analysis of networks

Today I read a paper titled “Detecting Important Nodes to Community Structure Using the Spectrum of the Graph”

The abstract is:
Many complex systems can be represented as networks, and how a network breaks up into subnetworks or communities is of wide interest

However, the development of a method to detect nodes important to communities that is both fast and accurate is a very challenging and open problem

In this manuscript, we introduce a new approach to characterize the node importance to communities

First, a centrality metric is proposed to measure the importance of network nodes to community structure using the spectrum of the adjacency matrix

We define the node importance to communities as the relative change in the eigenvalues of the network adjacency matrix upon their removal

Second, we also propose an index to distinguish two kinds of important nodes in communities, i.e., “community core” and “bridge”

Our indices are only relied on the spectrum of the graph matrix

They are applied in many artificial networks as well as many real-world networks

This new methodology gives us a basic approach to solve this challenging problem and provides a realistic result

Today I read a paper titled “Survey on Various Gesture Recognition Techniques for Interfacing Machines Based on Ambient Intelligence”

The abstract is:
Gesture recognition is mainly apprehensive on analyzing the functionality of human wits

The main goal of gesture recognition is to create a system which can recognize specific human gestures and use them to convey information or for device control

Hand gestures provide a separate complementary modality to speech for expressing ones ideas

Information associated with hand gestures in a conversation is degree,discourse structure, spatial and temporal structure

The approaches present can be mainly divided into Data-Glove Based and Vision Based approaches

An important face feature point is the nose tip

Since nose is the highest protruding point from the face

Besides that, it is not affected by facial expressions.Another important function of the nose is that it is able to indicate the head pose

Knowledge of the nose location will enable us to align an unknown 3D face with those in a face database

Eye detection is divided into eye position detection and eye contour detection

Existing works in eye detection can be classified into two major categories: traditional image-based passive approaches and the active IR based approaches

The former uses intensity and shape of eyes for detection and the latter works on the assumption that eyes have a reflection under near IR illumination and produce bright/dark pupil effect

The traditional methods can be broadly classified into three categories: template based methods,appearance based methods and feature based methods

The purpose of this paper is to compare various human Gesture recognition systems for interfacing machines directly to human wits without any corporeal media in an ambient environment

Today I read a paper titled “Irrelevance of information outflow in opinion dynamics models”

The abstract is:
The Sznajd model for opinion dynamics has attracted a large interest as a simple realization of the psychological principle of social validation

As its most salient feature, it has been claimed that the Sznajd model is qualitatively different from other ordering processes, because it is the only one featuring outflow of information as opposed to inflow

We show that this claim is unfounded by presenting a generalized zero-temperature Glauber-type of dynamics which yields results indistinguishable from those of the Sznajd model

In one-dimension we also derive an exact expression for the exit probability of the Sznajd model, that turns out to coincide with the result of an analytical approach based on the Kirkwood approximation

This observation raises interesting questions about the applicability and limitations of this approach

Today I read a paper titled “Mining User Comment Activity for Detecting Forum Spammers in YouTube”

The abstract is:
Research shows that comment spamming (comments which are unsolicited, unrelated, abusive, hateful, commercial advertisements etc) in online discussion forums has become a common phenomenon in Web 2.0 applications and there is a strong need to counter or combat comment spamming

We present a method to automatically detect comment spammer in YouTube (largest and a popular video sharing website) forums

The proposed technique is based on mining comment activity log of a user and extracting patterns (such as time interval between subsequent comments, presence of exactly same comment across multiple unrelated videos) indicating spam behavior

We perform empirical analysis on data crawled from YouTube and demonstrate that the proposed method is effective for the task of comment spammer detection

Today I read a paper titled “Physically-based particle simulation and visualization of pastes and gels”

The abstract is:
This paper is focused on the question of simulation and visualiza- tion of 3D gel and paste dynamic effects

In a first part, we introduce a 3D physically based particle (or mass-interaction) model, with a small number of masses and few powerful interaction parameters, which is able to generate the dynamic features of both gels and pastes

This model proves that the 3D mass-interaction method is relevant for the simulation of such phenomena, without an explicit knowledge of their underly- ing physics

In a second part, we expose an original rendering process, the Flow Structuring Method that enhances the dynamic properties of the simulation and offers a realistic visualization

This process ignores all the properties of the underlying physical model

It leads to a reconstruction of the spatial structure of the gel (or paste) flow only through an analysis of the output of the simula- tion which is a set of unorganized points moving in a 3D space

Finally, the paper presents realistic renderings obtained by using implicit surfaces and ray-tracing techniques on the Structured Flow previously obtained

Today I read a paper titled “Noise in Naming Games, partial synchronization and community detection in social networks”

The abstract is:
The Naming Games (NG) are agent-based models for agreement dynamics, peer pressure and herding in social networks, and protocol selection in autonomous ad-hoc sensor networks

By introducing a small noise term to the NG, the resulting Markov Chain model called Noisy Naming Games (NNG) are ergodic, in which all partial consensus states are recurrent

By using Gibbs-Markov equivalence we show how to get the NNG’s stationary distribution in terms of the local specification of a related Markov Random Field (MRF)

By ordering the partially-synchronized states according to their Gibbs energy, taken here to be a good measure of social tension, this method offers an enhanced method for community-detection in social interaction data

We show how the lowest Gibbs energy multi-name states separate and display the hidden community structures within a social network

Today I read a paper titled “Computation of the Travelling Salesman Problem by a Shrinking Blob”

The abstract is:
The Travelling Salesman Problem (TSP) is a well known and challenging combinatorial optimisation problem

Its computational intractability has attracted a number of heuristic approaches to generate satisfactory, if not optimal, candidate solutions

In this paper we demonstrate a simple unconventional computation method to approximate the Euclidean TSP using a virtual material approach

The morphological adaptation behaviour of the material emerges from the low-level interactions of a population of particles moving within a diffusive lattice

A `blob’ of this material is placed over a set of data points projected into the lattice, representing TSP city locations, and the blob is reduced in size over time

As the blob shrinks it morphologically adapts to the configuration of the cities

The shrinkage process automatically stops when the blob no longer completely covers all cities

By manually tracing the perimeter of the blob a path between cities is elicited corresponding to a TSP tour

Over 6 runs on 20 randomly generated datasets of 20 cities this simple and unguided method found tours with a mean best tour length of 1.04, mean average tour length of 1.07 and mean worst tour length of 1.09 when expressed as a fraction of the minimal tour computed by an exact TSP solver

We examine the insertion mechanism by which the blob constructs a tour, note some properties and limitations of its performance, and discuss the relationship between the blob TSP and proximity graphs which group points on the plane

The method is notable for its simplicity and the spatially represented mechanical mode of its operation

We discuss similarities between this method and previously suggested models of human performance on the TSP and suggest possibilities for further improvement

Today I read a paper titled “Injectivity of 2D Toric Bézier Patches”

The abstract is:
Rational Bezier functions are widely used as mapping functions in surface reparameterization, finite element analysis, image warping and morphing

The injectivity (one-to-one property) of a mapping function is typically necessary for these applications

Toric Bezier patches are generalizations of classical patches (triangular, tensor product) which are defined on the convex hull of a set of integer lattice points

We give a geometric condition on the control points that we show is equivalent to the injectivity of every 2D toric Bezier patch with those control points for all possible choices of weights

This condition refines that of Craciun, et al., which only implied injectivity on the interior of a patch

Today I read a paper titled “A mathematical model for networks with structures in the mesoscale”

The abstract is:
The new concept of multilevel network is introduced in order to embody some topological properties of complex systems with structures in the mesoscale which are not completely captured by the classical models

This new model, which generalizes the hyper-network and hyper-structure models, fits perfectly with several real-life complex systems, including social and public transportation networks

We present an analysis of the structural properties of the multilevel network, including the clustering and the metric structures

Some analytical relationships amongst the efficiency and clustering coefficient of this new model and the corresponding parameters of the underlying network are obtained

Finally some random models for multilevel networks are given to illustrate how different multilevel structures can produce similar underlying networks and therefore that the mesoscale structure should be taken into account in many applications

Today I read a paper titled “Understanding Cascading Failures in Power Grids”

The abstract is:
In the past, we have observed several large blackouts, i.e

loss of power to large areas

It has been noted by several researchers that these large blackouts are a result of a cascade of failures of various components

As a power grid is made up of several thousands or even millions of components (relays, breakers, transformers, etc.), it is quite plausible that a few of these components do not perform their function as desired

Their failure/misbehavior puts additional burden on the working components causing them to misbehave, and thus leading to a cascade of failures

The complexity of the entire power grid makes it difficult to model each and every individual component and study the stability of the entire system

For this reason, it is often the case that abstract models of the working of the power grid are constructed and then analyzed

These models need to be computationally tractable while serving as a reasonable model for the entire system

In this work, we construct one such model for the power grid, and analyze it

Today I read a paper titled “Sampling-based Algorithms for Optimal Motion Planning”

The abstract is:
During the last decade, sampling-based path planning algorithms, such as Probabilistic RoadMaps (PRM) and Rapidly-exploring Random Trees (RRT), have been shown to work well in practice and possess theoretical guarantees such as probabilistic completeness

However, little effort has been devoted to the formal analysis of the quality of the solution returned by such algorithms, e.g., as a function of the number of samples

The purpose of this paper is to fill this gap, by rigorously analyzing the asymptotic behavior of the cost of the solution returned by stochastic sampling-based algorithms as the number of samples increases

A number of negative results are provided, characterizing existing algorithms, e.g., showing that, under mild technical conditions, the cost of the solution returned by broadly used sampling-based algorithms converges almost surely to a non-optimal value

The main contribution of the paper is the introduction of new algorithms, namely, PRM* and RRT*, which are provably asymptotically optimal, i.e., such that the cost of the returned solution converges almost surely to the optimum

Moreover, it is shown that the computational complexity of the new algorithms is within a constant factor of that of their probabilistically complete (but not asymptotically optimal) counterparts

The analysis in this paper hinges on novel connections between stochastic sampling-based path planning algorithms and the theory of random geometric graphs

Today I read a paper titled “Gyroscopically Stabilized Robot: Balance and Tracking”

The abstract is:
The single wheel, gyroscopically stabilized robot – Gyrover, is a dynamically stable but statically unstable, underactuated system

In this paper, based on the dynamic model of the robot, we investigate two classes of nonholonomic constraints associated with the system

Then, based on the backstepping technology, we propose a control law for balance control of Gyrover

Next, through transferring the systems states from Cartesian coordinate to polar coordinate, control laws for point-to-point control and line tracking in Cartesian space are provided

Today I read a paper titled “The Impact of Visual Appearance on User Response in Online Display Advertising”

The abstract is:
Display advertising has been a significant source of revenue for publishers and ad networks in online advertising ecosystem

One of the main goals in display advertising is to maximize user response rate for advertising campaigns, such as click through rates (CTR) or conversion rates

Although in the online advertising industry we believe that the visual appearance of ads (creatives) matters for propensity of user response, there is no published work so far to address this topic via a systematic data-driven approach

In this paper we quantitatively study the relationship between the visual appearance and performance of creatives using large scale data in the world’s largest display ads exchange system, RightMedia

We designed a set of 43 visual features, some of which are novel and some are inspired by related work

We extracted these features from real creatives served on RightMedia

We also designed and conducted a series of experiments to evaluate the effectiveness of visual features for CTR prediction, ranking and performance classification

Based on the evaluation results, we selected a subset of features that have the most important impact on CTR

We believe that the findings presented in this paper will be very useful for the online advertising industry in designing high-performance creatives

It also provides the research community with the first ever data set, initial insights into visual appearance’s effect on user response propensity, and evaluation benchmarks for further study

Today I read a paper titled “Asynchronous Decentralized Algorithm for Space-Time Cooperative Pathfinding”

The abstract is:
Cooperative pathfinding is a multi-agent path planning problem where a group of vehicles searches for a corresponding set of non-conflicting space-time trajectories

Many of the practical methods for centralized solving of cooperative pathfinding problems are based on the prioritized planning strategy

However, in some domains (e.g., multi-robot teams of unmanned aerial vehicles, autonomous underwater vehicles, or unmanned ground vehicles) a decentralized approach may be more desirable than a centralized one due to communication limitations imposed by the domain and/or privacy concerns

In this paper we present an asynchronous decentralized variant of prioritized planning ADPP and its interruptible version IADPP

The algorithm exploits the inherent parallelism of distributed systems and allows for a speed up of the computation process

Unlike the synchronized planning approaches, the algorithm allows an agent to react to updates about other agents’ paths immediately and invoke its local spatio-temporal path planner to find the best trajectory, as response to the other agents’ choices

We provide a proof of correctness of the algorithms and experimentally evaluate them on synthetic domains

Today I read a paper titled “Automatic Image Segmentation by Dynamic Region Merging”

The abstract is:
This paper addresses the automatic image segmentation problem in a region merging style

With an initially over-segmented image, in which the many regions (or super-pixels) with homogeneous color are detected, image segmentation is performed by iteratively merging the regions according to a statistical test

There are two essential issues in a region merging algorithm: order of merging and the stopping criterion

In the proposed algorithm, these two issues are solved by a novel predicate, which is defined by the sequential probability ratio test (SPRT) and the maximum likelihood criterion

Starting from an over-segmented image, neighboring regions are progressively merged if there is an evidence for merging according to this predicate

We show that the merging order follows the principle of dynamic programming

This formulates image segmentation as an inference problem, where the final segmentation is established based on the observed image

We also prove that the produced segmentation satisfies certain global properties

In addition, a faster algorithm is developed to accelerate the region merging process, which maintains a nearest neighbor graph in each iteration

Experiments on real natural images are conducted to demonstrate the performance of the proposed dynamic region merging algorithm

Today I read a paper titled “Content-Based Filtering for Video Sharing Social Networks”

The abstract is:
In this paper we compare the use of several features in the task of content filtering for video social networks, a very challenging task, not only because the unwanted content is related to very high-level semantic concepts (e.g., pornography, violence, etc.) but also because videos from social networks are extremely assorted, preventing the use of constrained a priori information

We propose a simple method, able to combine diverse evidence, coming from different features and various video elements (entire video, shots, frames, keyframes, etc.)

We evaluate our method in three social network applications, related to the detection of unwanted content – pornographic videos, violent videos, and videos posted to artificially manipulate popularity scores

Using challenging test databases, we show that this simple scheme is able to obtain good results, provided that adequate features are chosen

Moreover, we establish a representation using codebooks of spatiotemporal local descriptors as critical to the success of the method in all three contexts

This is consequential, since the state-of-the-art still relies heavily on static features for the tasks addressed

Today I read a paper titled “A Parameterized Centrality Metric for Network Analysis”

The abstract is:
A variety of metrics have been proposed to measure the relative importance of nodes in a network

One of these, alpha-centrality [Bonacich, 2001], measures the number of attenuated paths that exist between nodes

We introduce a normalized version of this metric and use it to study network structure, specifically, to rank nodes and find community structure of the network

Specifically, we extend the modularity-maximization method [Newman and Girvan, 2004] for community detection to use this metric as the measure of node connectivity

Normalized alpha-centrality is a powerful tool for network analysis, since it contains a tunable parameter that sets the length scale of interactions

By studying how rankings and discovered communities change when this parameter is varied allows us to identify locally and globally important nodes and structures

We apply the proposed method to several benchmark networks and show that it leads to better insight into network structure than alternative methods

Today I read a paper titled “Dynamic Multi-Vehicle Routing with Multiple Classes of Demands”

The abstract is:
In this paper we study a dynamic vehicle routing problem in which there are multiple vehicles and multiple classes of demands

Demands of each class arrive in the environment randomly over time and require a random amount of on-site service that is characteristic of the class

To service a demand, one of the vehicles must travel to the demand location and remain there for the required on-site service time

The quality of service provided to each class is given by the expected delay between the arrival of a demand in the class, and that demand’s service completion

The goal is to design a routing policy for the service vehicles which minimizes a convex combination of the delays for each class

First, we provide a lower bound on the achievable values of the convex combination of delays

Then, we propose a novel routing policy and analyze its performance under heavy load conditions (i.e., when the fraction of time the service vehicles spend performing on-site service approaches one)

The policy performs within a constant factor of the lower bound (and thus the optimal), where the constant depends only on the number of classes, and is independent of the number of vehicles, the arrival rates of demands, the on-site service times, and the convex combination coefficients

Today I read a paper titled “Stochastic Surveillance Strategies for Spatial Quickest Detection”

The abstract is:
We design persistent surveillance strategies for the quickest detection of anomalies taking place in an environment of interest

From a set of predefined regions in the environment, a team of autonomous vehicles collects noisy observations, which a control center processes

The overall objective is to minimize detection delay while maintaining the false alarm rate below a desired threshold

We present joint (i) anomaly detection algorithms for the control center and (ii) vehicle routing policies

For the control center, we propose parallel cumulative sum (CUSUM) algorithms (one for each region) to detect anomalies from noisy observations

For the vehicles, we propose a stochastic routing policy, in which the regions to be visited are chosen according to a probability vector

We study stationary routing policy (the probability vector is constant) as well as adaptive routing policies (the probability vector varies in time as a function of the likelihood of regional anomalies)

In the context of stationary policies, we design a performance metric and minimize it to design an efficient stationary routing policy

Our adaptive policy improves upon the stationary counterpart by adaptively increasing the selection probability of regions with high likelihood of anomaly

Finally, we show the effectiveness of the proposed algorithms through numerical simulations and a persistent surveillance experiment

Today I read a paper titled “Detecting Separation in Robotic and Sensor Networks”

The abstract is:
In this paper we consider the problem of monitoring detecting separation of agents from a base station in robotic and sensor networks

Such separation can be caused by mobility and/or failure of the agents

While separation/cut detection may be performed by passing messages between a node and the base in static networks, such a solution is impractical for networks with high mobility, since routes are constantly changing

We propose a distributed algorithm to detect separation from the base station

The algorithm consists of an averaging scheme in which every node updates a scalar state by communicating with its current neighbors

We prove that if a node is permanently disconnected from the base station, its state converges to $0$

If a node is connected to the base station in an average sense, even if not connected in any instant, then we show that the expected value of its state converges to a positive number

Therefore, a node can detect if it has been separated from the base station by monitoring its state

The effectiveness of the proposed algorithm is demonstrated through simulations, a real system implementation and experiments involving both static as well as mobile networks

Today I read a paper titled “Brain-Computer Interface Controlled Robotic Gait Orthosis”

The abstract is:
Reliance on wheelchairs after spinal cord injury (SCI) leads to many medical co-morbidities

Treatment of these conditions contributes to the majority of SCI health care costs

Restoring able-body-like ambulation after SCI may reduce the incidence of these conditions, and increase independence and quality of life

However, no biomedical solution exists that can reverse this lost neurological function, and hence novel methods are needed

Brain-computer interface (BCI) controlled lower extremity prosthesis may constitute one such novel approach

One subject with able-body and one with paraplegia due to SCI underwent electroencephalogram (EEG) recording while engaged in alternating epochs of idling and walking kinesthetic motor imagery (KMI)

These data were analyzed to generate an EEG prediction model for online BCI operation

A commercial robotic gait orthosis (RoGO) system (treadmill suspended), was interfaced with the BCI computer

In an online test, the subjects were tasked to ambulate using the BCI-RoGO system when prompted by computerized cues

The performance of this system was assessed with cross-correlation analysis, and omission and false alarm rates

The offline accuracy of the EEG prediction model averaged 86.3%

The cross-correlation between instructional cues and BCI-RoGO walking epochs averaged 0.812 +/- 0.048 (p-value<10^-4)

There were on average 0.8 false alarms per session and no omissions

This is the first time a person with parapegia due to SCI regained basic brain-controlled ambulation, thereby indicating that restoring brain-controlled ambulation is feasible

Future work will test this system in a population of individuals with SCI

If successful, this may justify future development of invasive BCI-controlled lower extremity prostheses

This system may also be applied to incomplete SCI to improve neurological outcomes beyond those of standard physiotherapy

Today I read a paper titled “Characterizing and approximating eigenvalue sets of symmetric interval matrices”

The abstract is:
We consider the eigenvalue problem for the case where the input matrix is symmetric and its entries perturb in some given intervals

We present a characterization of some of the exact boundary points, which allows us to introduce an inner approximation algorithm, that in many case estimates exact bounds

To our knowledge, this is the first algorithm that is able to guaran- tee exactness

We illustrate our approach by several examples and numerical experiments

Today I read a paper titled “Detecting Friendship Within Dynamic Online Interaction Networks”

The abstract is:
In many complex social systems, the timing and frequency of interactions between individuals are observable but friendship ties are hidden

Recovering these hidden ties, particularly for casual users who are relatively less active, would enable a wide variety of friendship-aware applications in domains where labeled data are often unavailable, including online advertising and national security

Here, we investigate the accuracy of multiple statistical features, based either purely on temporal interaction patterns or on the cooperative nature of the interactions, for automatically extracting latent social ties

Using self-reported friendship and non-friendship labels derived from an anonymous online survey, we learn highly accurate predictors for recovering hidden friendships within a massive online data set encompassing 18 billion interactions among 17 million individuals of the popular online game Halo: Reach

We find that the accuracy of many features improves as more data accumulates, and cooperative features are generally reliable

However, periodicities in interaction time series are sufficient to correctly classify 95% of ties, even for casual users

These results clarify the nature of friendship in online social environments and suggest new opportunities and new privacy concerns for friendship-aware applications that do not require the disclosure of private friendship information

Today I read a paper titled “A Neural Network Classifier of Volume Datasets”

The abstract is:
Many state-of-the art visualization techniques must be tailored to the specific type of dataset, its modality (CT, MRI, etc.), the recorded object or anatomical region (head, spine, abdomen, etc.) and other parameters related to the data acquisition process

While parts of the information (imaging modality and acquisition sequence) may be obtained from the meta-data stored with the volume scan, there is important information which is not stored explicitly (anatomical region, tracing compound)

Also, meta-data might be incomplete, inappropriate or simply missing

This paper presents a novel and simple method of determining the type of dataset from previously defined categories

2D histograms based on intensity and gradient magnitude of datasets are used as input to a neural network, which classifies it into one of several categories it was trained with

The proposed method is an important building block for visualization systems to be used autonomously by non-experts

The method has been tested on 80 datasets, divided into 3 classes and a “rest” class

A significant result is the ability of the system to classify datasets into a specific class after being trained with only one dataset of that class

Other advantages of the method are its easy implementation and its high computational performance

Today I read a paper titled “Sensor Management: Past, Present, and Future”

The abstract is:
Sensor systems typically operate under resource constraints that prevent the simultaneous use of all resources all of the time

Sensor management becomes relevant when the sensing system has the capability of actively managing these resources; i.e., changing its operating configuration during deployment in reaction to previous measurements

Examples of systems in which sensor management is currently used or is likely to be used in the near future include autonomous robots, surveillance and reconnaissance networks, and waveform-agile radars

This paper provides an overview of the theory, algorithms, and applications of sensor management as it has developed over the past decades and as it stands today

Today I read a paper titled “Robotic Applications in Cardiac Surgery”

The abstract is:
Traditionally, cardiac surgery has been performed through a median sternotomy, which allows the surgeon generous access to the heart and surrounding great vessels

As a paradigm shift in the size and location of incisions occurs in cardiac surgery, new methods have been developed to allow the surgeon the same amount of dexterity and accessibility to the heart in confined spaces and in a less invasive manner

Initially, long instruments without pivot points were used, however, more recent robotic telemanipulation systems have been applied that allow for improved dexterity, enabling the surgeon to perform cardiac surgery from a distance not previously possible

In this rapidly evolving field, we review the recent history and clinical results of using robotics in cardiac surgery

Today I read a paper titled “Analyzing the Social Structure and Dynamics of E-mail and Spam in Massive Backbone Internet Traffic”

The abstract is:
E-mail is probably the most popular application on the Internet, with everyday business and personal communications dependent on it

Spam or unsolicited e-mail has been estimated to cost businesses significant amounts of money

However, our understanding of the network-level behavior of legitimate e-mail traffic and how it differs from spam traffic is limited

In this study, we have passively captured SMTP packets from a 10 Gbit/s Internet backbone link to construct a social network of e-mail users based on their exchanged e-mails

The focus of this paper is on the graph metrics indicating various structural properties of e-mail networks and how they evolve over time

This study also looks into the differences in the structural and temporal characteristics of spam and non-spam networks

Our analysis on the collected data allows us to show several differences between the behavior of spam and legitimate e-mail traffic, which can help us to understand the behavior of spammers and give us the knowledge to statistically model spam traffic on the network-level in order to complement current spam detection techniques

Today I read a paper titled “Design and Construction of a Brain-Like Computer: A New Class of Frequency-Fractal Computing Using Wireless Communication in a Supramolecular Organic, Inorganic System”

The abstract is:
Here, we introduce a new class of computer which does not use any circuit or logic gate

In fact, no program needs to be written: it learns by itself and writes its own program to solve a problem

Godels incompleteness argument is explored here to devise an engine where an astronomically large number of IfThen arguments are allowed to grow by self assembly, based on the basic set of arguments written in the system, thus, we explore the beyond Turing path of computing but following a fundamentally different route adopted in the last half a century old non Turing adventures

Our hardware is a multilayered seed structure

If we open the largest seed, which is the final hardware, we find several computing seed structures inside, if we take any of them and open, there are several computing seeds inside

We design and synthesize the smallest seed, the entire multilayered architecture grows by itself

The electromagnetic resonance band of each seed looks similar, but the seeds of any layer shares a common region in its resonance band with inner and upper layer, hence a chain of resonance bands is formed (frequency fractal) connecting the smallest to the largest seed (hence the name invincible rhythm or Ajeya Chhandam in Sanskrit)

Today I read a paper titled “Assembly and Disassembly Planning by using Fuzzy Logic & Genetic Algorithms”

The abstract is:
The authors propose the implementation of hybrid Fuzzy Logic-Genetic Algorithm (FL-GA) methodology to plan the automatic assembly and disassembly sequence of products

The GA-Fuzzy Logic approach is implemented onto two levels

The first level of hybridization consists of the development of a Fuzzy controller for the parameters of an assembly or disassembly planner based on GAs

This controller acts on mutation probability and crossover rate in order to adapt their values dynamically while the algorithm runs

The second level consists of the identification of theoptimal assembly or disassembly sequence by a Fuzzy function, in order to obtain a closer control of the technological knowledge of the assembly/disassembly process

Two case studies were analyzed in order to test the efficiency of the Fuzzy-GA methodologies

Today I read a paper titled “An Approach For Robots To Deal With Objects”

The abstract is:
Understanding object and its context are very important for robots when dealing with objects for completion of a mission

In this paper, an Affordance-based Ontology (ABO) is proposed for easy robot dealing with substantive and non-substantive objects

An ABO is a machine-understandable representation of objects and their relationships by what it’s related to and how it’s related

By using ABO, when dealing with a substantive object, robots can understand the representation of its object and its relation with other non-substantive objects

When the substantive object is not available, the robots have the understanding ability, in term of objects and their functions to select a non substantive object in order to complete the mission, such as giving raincoat or hat instead of getting stuck due to the unavailability of substantive object, e.g

umbrella

The experiment is done in the Ubiquitous Robotics Technology (u-RT) Space of National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan

Today I read a paper titled “Using virtual human for an interactive customer-oriented constrained environment design”

The abstract is:
For industrial product design, it is very important to take into account assembly/disassembly and maintenance operations during the conceptual and prototype design stage

For these operations or other similar operations in a constrained environment, trajectory planning is always a critical and difficult issue for evaluating the design or for the users’ convenience

In this paper, a customer-oriented approach is proposed to partially solve ergonomic issues encountered during the design stage of a constrained environment

A single objective optimization based method is taken from the literature to generate the trajectory in a constrained environment automatically

A motion capture based method assists to guide the trajectory planning interactively if a local minimum is encountered within the single objective optimization

At last, a multi-objective evaluation method is proposed to evaluate the operations generated by the algorithm

Today I read a paper titled “NL Understanding with a Grammar of Constructions”

The abstract is:
We present an approach to natural language understanding based on a computable grammar of constructions

A “construction” consists of a set of features of form and a description of meaning in a context

A grammar is a set of constructions

This kind of grammar is the key element of Mincal, an implemented natural language, speech-enabled interface to an on-line calendar system

The system consists of a NL grammar, a parser, an on-line calendar, a domain knowledge base (about dates, times and meetings), an application knowledge base (about the calendar), a speech recognizer, a speech generator, and the interfaces between those modules

We claim that this architecture should work in general for spoken interfaces in small domains

In this paper we present two novel aspects of the architecture: (a) the use of constructions, integrating descriptions of form, meaning and context into one whole; and (b) the separation of domain knowledge from application knowledge

We describe the data structures for encoding constructions, the structure of the knowledge bases, and the interactions of the key modules of the system.

Today I read a paper titled “The effects of graphical interface design characteristics on human-computer interaction task efficiency”

The abstract is:
The main objective of this paper was to investigate the effects of a computer screen interface design and its related geometrical characteristics of 36 graphical objects on a user’s task efficiency

A total of 490 subjects took part in laboratory experiments that focused on the direct manipulation of a visual dialogue between a user and a computer

The subjects were asked to select an object from among a group of items randomly placed on the computer screen that were visible exclusively during the visual search process

A model expressing the mean object acquisition time as a function of graphical object size and the configuration was developed and statistically validated

The model showed an influence of geometrical design characteristics of the graphical objects (icons) and their groupings (icon structures) on the observed task efficiency

The reported results can be used at those stages of a software lifecycle that concentrate on prototyping, designing, and implementing graphical solutions for the efficient graphical user-computer interface

Today I read a paper titled “On Linear Spaces of Polyhedral Meshes”

The abstract is:
Polyhedral meshes (PM) – meshes having planar faces – have enjoyed a rise in popularity in recent years due to their importance in architectural and industrial design

However, they are also notoriously difficult to generate and manipulate

Previous methods start with a smooth surface and then apply elaborate meshing schemes to create polyhedral meshes approximating the surface

In this paper, we describe a reverse approach: given the topology of a mesh, we explore the space of possible planar meshes with that topology

Our approach is based on a complete characterization of the maximal linear spaces of polyhedral meshes contained in the curved manifold of polyhedral meshes with a given topology

We show that these linear spaces can be described as nullspaces of differential operators, much like harmonic functions are nullspaces of the Laplacian operator

An analysis of this operator provides tools for global and local design of a polyhedral mesh, which fully expose the geometric possibilities and limitations of the given topology

Today I read a paper titled “Interactive Character Posing by Sparse Coding”

The abstract is:
Character posing is of interest in computer animation

It is difficult due to its dependence on inverse kinematics (IK) techniques and articulate property of human characters

To solve the IK problem, classical methods that rely on numerical solutions often suffer from the under-determination problem and can not guarantee naturalness

Existing data-driven methods address this problem by learning from motion capture data

When facing a large variety of poses however, these methods may not be able to capture the pose styles or be applicable in real-time environment

Inspired from the low-rank motion de-noising and completion model in lai2011motion, we propose a novel model for character posing based on sparse coding

Unlike conventional approaches, our model directly captures the pose styles in Euclidean space to provide intuitive training error measurements and facilitate pose synthesis

A pose dictionary is learned in training stage and based on it natural poses are synthesized to satisfy users’ constraints

We compare our model with existing models for tasks of pose de-noising and completion

Experiments show our model obtains lower de-noising and completion error

We also provide User Interface(UI) examples illustrating that our model is effective for interactive character posing

Today I read a paper titled “A novel 2.5D approach for interfacing with web applications”

The abstract is:
Web applications need better user interface to be interactive and attractive

A new approach/concept of dimensional enhancement – 2.5D “a 2D display of a virtual 3D environment”, which can be implemented in social networking sites and further in other system applications

Today I read a paper titled “Who is the best player ever? A complex network analysis of the history of professional tennis”

The abstract is:
We consider all matches played by professional tennis players between 1968 and 2010, and, on the basis of this data set, construct a directed and weighted network of contacts

The resulting graph shows complex features, typical of many real networked systems studied in literature

We develop a diffusion algorithm and apply it to the tennis contact network in order to rank professional players

Jimmy Connors is identified as the best player of the history of tennis according to our ranking procedure

We perform a complete analysis by determining the best players on specific playing surfaces as well as the best ones in each of the years covered by the data set

The results of our technique are compared to those of two other well established methods

In general, we observe that our ranking method performs better: it has a higher predictive power and does not require the arbitrary introduction of external criteria for the correct assessment of the quality of players

The present work provides a novel evidence of the utility of tools and methods of network theory in real applications

Today I read a paper titled “Using evolutionary design to interactively sketch car silhouettes and stimulate designer’s creativity”

The abstract is:
An Interactive Genetic Algorithm is proposed to progressively sketch the desired side-view of a car profile

It adopts a Fourier decomposition of a 2D profile as the genotype, and proposes a cross-over mechanism

In addition, a formula function of two genes’ discrepancies is fitted to the perceived dissimilarity between two car profiles

This similarity index is intensively used, throughout a series of user tests, to highlight the added value of the IGA compared to a systematic car shape exploration, to prove its ability to create superior satisfactory designs and to stimulate designer’s creativity

These tests have involved six designers with a design goal defined by a semantic attribute

The results reveal that if “friendly” is diversely interpreted in terms of car shapes, “sportive” denotes a very conventional representation which may be a limitation for shape renewal

Today I read a paper titled “Haptics in computer music : a paradigm shift”

The abstract is:
With an historical point of view combined with a bibliographic overview, the article discusses the idea that haptic force feedback transducers correspond with a paradigm shift in our real-time tools for creating music

So doing, il shows that computer music may be regarded as a major field of research and application for haptics

Today I read a paper titled “A Spectral Learning Approach to Range-Only SLAM”

The abstract is:
We present a novel spectral learning algorithm for simultaneous localization and mapping (SLAM) from range data with known correspondences

This algorithm is an instance of a general spectral system identification framework, from which it inherits several desirable properties, including statistical consistency and no local optima

Compared with popular batch optimization or multiple-hypothesis tracking (MHT) methods for range-only SLAM, our spectral approach offers guaranteed low computational requirements and good tracking performance

Compared with popular extended Kalman filter (EKF) or extended information filter (EIF) approaches, and many MHT ones, our approach does not need to linearize a transition or measurement model; such linearizations can cause severe errors in EKFs and EIFs, and to a lesser extent MHT, particularly for the highly non-Gaussian posteriors encountered in range-only SLAM

We provide a theoretical analysis of our method, including finite-sample error bounds

Finally, we demonstrate on a real-world robotic SLAM problem that our algorithm is not only theoretically justified, but works well in practice: in a comparison of multiple methods, the lowest errors come from a combination of our algorithm with batch optimization, but our method alone produces nearly as good a result at far lower computational cost

Today I read a paper titled “Random Topologies and the emergence of cooperation: the role of short-cuts”

The abstract is:
We study in detail the role of short-cuts in promoting the emergence of cooperation in a network of agents playing the Prisoner’s Dilemma Game (PDG)

We introduce a model whose topology interpolates between the one-dimensional euclidean lattice (a ring) and the complete graph by changing the value of one parameter (the probability p to add a link between two nodes not already connected in the euclidean configuration)

We show that there is a region of values of p in which cooperation is largely enhanced, whilst for smaller values of p only a few cooperators are present in the final state, and for p \rightarrow 1- cooperation is totally suppressed

We present analytical arguments that provide a very plausible interpretation of the simulation results, thus unveiling the mechanism by which short-cuts contribute to promote (or suppress) cooperation

Today I read a paper titled “Fuzzy overlapping communities in networks”

The abstract is:
Networks commonly exhibit a community structure, whereby groups of vertices are more densely connected to each other than to other vertices

Often these communities overlap, such that each vertex may occur in more than one community

However, two distinct types of overlapping are possible: crisp (where each vertex belongs fully to each community of which it is a member) and fuzzy (where each vertex belongs to each community to a different extent)

We investigate the effects of the fuzziness of community overlap

We find that it has a strong effect on the performance of community detection methods: some algorithms perform better with fuzzy overlapping while others favour crisp overlapping

We also evaluate the performance of some algorithms that recover the belonging coefficients when the overlap is fuzzy

Finally, we investigate whether real networks contain fuzzy or crisp overlapping

Today I read a paper titled “Optimal Probabilistic Ring Exploration by Asynchronous Oblivious Robots”

The abstract is:
We consider a team of $k$ identical, oblivious, asynchronous mobile robots that are able to sense i.e., view) their environment, yet are unable to communicate, and evolve on a constrained path

Previous results in this weak scenario show that initial symmetry yields high lower bounds when problems are to be solved by deterministic robots

In this paper, we initiate research on probabilistic bounds and solutions in this context, and focus on the exploration problem of anonymous unoriented rings of any size

It is known that $\Theta(\log n)$ robots are necessary and sufficient to solve the problem with $k$ deterministic robots, provided that $k$ and $n$ are coprime

By contrast, we show that four identical probabilistic robots are necessary and sufficient to solve the same problem, also removing the coprime constraint

Our positive results are constructive

Today I read a paper titled “Effective Mechanism for Social Recommendation of News”

The abstract is:
Recommendation systems represent an important tool for news distribution on the Internet

In this work we modify a recently proposed social recommendation model in order to deal with no explicit ratings of users on news

The model consists of a network of users which continually adapts in order to achieve an efficient news traffic

To optimize network’s topology we propose different stochastic algorithms that are scalable with respect to the network’s size

Agent-based simulations reveal the features and the performance of these algorithms

To overcome the resultant drawbacks of each method we introduce two improved algorithms and show that they can optimize network’s topology almost as fast and effectively as other not-scalable methods that make use of much more information

Today I read a paper titled “Circadian pattern and burstiness in mobile phone communication”

The abstract is:
The temporal communication patterns of human individuals are known to be inhomogeneous or bursty, which is reflected as the heavy tail behavior in the inter-event time distribution

As the cause of such bursty behavior two main mechanisms have been suggested: a) Inhomogeneities due to the circadian and weekly activity patterns and b) inhomogeneities rooted in human task execution behavior

Here we investigate the roles of these mechanisms by developing and then applying systematic de-seasoning methods to remove the circadian and weekly patterns from the time-series of mobile phone communication events of individuals

We find that the heavy tails in the inter-event time distributions remain robustly with respect to this procedure, which clearly indicates that the human task execution based mechanism is a possible cause for the remaining burstiness in temporal mobile phone communication patterns