Archives for 2014

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 “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 “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 “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 “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 “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 “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

Today I read a paper titled “Simulation Techniques and Prosthetic Approach Towards Biologically Efficient Artificial Sense Organs- An Overview”

The abstract is:
An overview of the applications of control theory to prosthetic sense organs including the senses of vision, taste and odor is being presented in this paper

Simulation aspect nowadays has been the centre of research in the field of prosthesis

There have been various successful applications of prosthetic organs, in case of natural biological organs dis-functioning patients

Simulation aspects and control modeling are indispensible for knowing system performance, and to generate an original approach of artificial organs

This overview focuses mainly on control techniques, by far a theoretical overview and fusion of artificial sense organs trying to mimic the efficacies of biologically active sensory organs

Keywords: virtual reality, prosthetic vision, artificial