OpenRaiser/Intern-Atlas huggingface dataset:
Off-Line Handwritten Signature Identification Using Rotated Complex Wavelet Filters
Venue: arXiv cs.CV 2011
Year: 2011

In this paper, a new method for handwritten signature identification based on rotated complex wavelet filters is proposed. We have proposed to use the rotated complex wavelet filters (RCWF) and dual tree complex wavelet transform(DTCWT) together to derive signature feature extraction, which captures information in twelve different directions. In identification phase, Canberra distance measure is used. The proposed method is compared with discrete wavelet transform (DWT). From experimental results it is found that signature identification rate of proposed method is superior over DWT
Distributed Learning Policies for Power Allocation in Multiple Access Channels
Venue: arXiv cs.GT 2011
Year: 2011

We analyze the problem of distributed power allocation for orthogonal multiple access channels by considering a continuous non-cooperative game whose strategy space represents the users' distribution of transmission power over the network's channels. When the channels are static, we find that this game admits an exact potential function and this allows us to show that it has a unique equilibrium almost surely. Furthermore, using the game's potential property, we derive a modified version of the replicator dynamics of evolutionary game theory which applies to this continuous game, and we show that if the network's users employ a distributed learning scheme based on these dynamics, then they converge to equilibrium exponentially quickly. On the other hand, a major challenge occurs if the channels do not remain static but fluctuate stochastically over time, following a stationary ergodic process. In that case, the associated ergodic game still admits a unique equilibrium, but the learning analysis becomes much more complicated because the replicator dynamics are no longer deterministic. Nonetheless, by employing results from the theory of stochastic approximation, we show that users still converge to the game's unique equilibrium. Our analysis hinges on a game-theoretical result which is of independent interest: in finite player games which admit a (possibly nonlinear) convex potential function, the replicator dynamics (suitably modified to account for nonlinear payoffs) converge to an eps-neighborhood of an equilibrium at time of order O(log(1/eps)).
On a Connection between Ideal Two-level Autocorrelation and Almost Balancedness of $p$-ary Sequences
Venue: arXiv cs.IT 2011
Year: 2011

In this correspondence, for every periodic $p-$ary sequence satisfying ideal two-level autocorrelation property the existence of an element of the field ${\bf GF}(p)$ which appears one time less than all the rest that are equally distributed in a period of that sequence, is proved by algebraic method. In addition, it is shown that such a special element might not be only the zero element but as well arbitrary element of that field.
Integration of Communication Analysis and the OO-Method: Rules for the manual derivation of the Conceptual Model
Venue: arXiv cs.SE 2011
Year: 2011

Enterprise information systems can be developed following a model-driven paradigm. This way, models that represent the organisational work practice are used to produce models that represent the information system. Current software development methods are starting to provide guidelines for the construction of conceptual models, taking as input requirements models. This paper proposes the integration of two methods: Communication Analysis (a communication-oriented requirements engineering method [España, González et al. 2009]) and the OO-Method (a model-driven object-oriented software development method [Pastor and Molina 2007]). For this purpose, a systematic technique for deriving OO-Method Conceptual Models from business process and requirements models is proposed. The business process specifications (which include message structures) are processed in order to obtain static and dynamic views of the computerised information system. Then, using the OLIVANOVA framework, software source code can be generated automatically [CARE Technologies].
Cost Based Satisficing Search Considered Harmful
Venue: arXiv cs.AI 2011
Year: 2011

Recently, several researchers have found that cost-based satisficing search with A* often runs into problems. Although some "work arounds" have been proposed to ameliorate the problem, there has not been any concerted effort to pinpoint its origin. In this paper, we argue that the origins can be traced back to the wide variance in action costs that is observed in most planning domains. We show that such cost variance misleads A* search, and that this is no trifling detail or accidental phenomenon, but a systemic weakness of the very concept of "cost-based evaluation functions + systematic search + combinatorial graphs". We show that satisficing search with sized-based evaluation functions is largely immune to this problem.
The key exchange cryptosystem used with higher order Diophantine equations
Venue: arXiv cs.IT 2011
Year: 2011

One-way functions are widely used for encrypting the secret in public key cryptography, although they are regarded as plausibly one-way but have not been proven so. Here we discuss the public key cryptosystem based on the system of higher order Diophantine equations. In this system those Diophantine equations are used as public keys for sender and recipient, and sender can recover the secret from the Diophantine equation returned from recipient with a trapdoor. In general the system of Diophantine equations is hard to solve when it is positive-dimensional and it implies the Diophantine equations in this cryptosystem works as a possible one-way function. We also discuss some problems on implementation, which are caused from additional complexity necessary for constructing Diophantine equations in order to prevent from attacking by tamperers.
Image Encryption Based on Diffusion and Multiple Chaotic Maps
Venue: arXiv cs.CR 2011
Year: 2011

In the recent world, security is a prime important issue, and encryption is one of the best alternative way to ensure security. More over, there are many image encryption schemes have been proposed, each one of them has its own strength and weakness. This paper presents a new algorithm for the image encryption/decryption scheme. This paper is devoted to provide a secured image encryption technique using multiple chaotic based circular mapping. In this paper, first, a pair of sub keys is given by using chaotic logistic maps. Second, the image is encrypted using logistic map sub key and in its transformation leads to diffusion process. Third, sub keys are generated by four different chaotic maps. Based on the initial conditions, each map may produce various random numbers from various orbits of the maps. Among those random numbers, a particular number and from a particular orbit are selected as a key for the encryption algorithm. Based on the key, a binary sequence is generated to control the encryption algorithm. The input image of 2-D is transformed into a 1- D array by using two different scanning pattern (raster and Zigzag) and then divided into various sub blocks. Then the position permutation and value permutation is applied to each binary matrix based on multiple chaos maps. Finally the receiver uses the same sub keys to decrypt the encrypted images. The salient features of the proposed image encryption method are loss-less, good peak signal-to-noise ratio (PSNR), Symmetric key encryption, less cross correlation, very large number of secret keys, and key-dependent pixel value replacement.
A New Dynamic Round Robin and SRTN Algorithm with Variable Original Time Slice and Intelligent Time Slice for Soft Real Time Systems
Venue: arXiv cs.OS 2011
Year: 2011

The main objective of the paper is to improve the Round Robin (RR) algorithm using dynamic ITS by coalescing it with Shortest Remaining Time Next (SRTN) algorithm thus reducing the average waiting time, average turnaround time and the number of context switches. The original time slice has been calculated for each process based on its burst time.This is mostly suited for soft real time systems where meeting of deadlines is desirable to increase its performance. The advantage is that processes that are closer to their remaining completion time will get more chances to execute and leave the ready queue. This will reduce the number of processes in the ready queue by knocking out short jobs relatively faster in a hope to reduce the average waiting time, turn around time and number of context switches. This paper improves the algorithm [8] and the experimental analysis shows that the proposed algorithm performs better than algorithm [6] and [8] when the processes are having an increasing order, decreasing order and random order of burst time.
Probability Bracket Notation, Term Vector Space, Concept Fock Space and Induced Probabilistic IR Models
Venue: arXiv cs.IR 2011
Year: 2011

After a brief introduction to Probability Bracket Notation (PBN) for discrete random variables in time-independent probability spaces, we apply both PBN and Dirac notation to investigate probabilistic modeling for information retrieval (IR). We derive the expressions of relevance of document to query (RDQ) for various probabilistic models, induced by Term Vector Space (TVS) and by Concept Fock Space (CFS). The inference network model (INM) formula is symmetric and can be used to evaluate relevance of document to document (RDD); the CFS-induced models contain ingredients of all three classical IR models. The relevance formulas are tested and compared on different scenarios against a famous textbook example.
LDPC Code Design for the BPSK-constrained Gaussian Wiretap Channel
Venue: arXiv cs.IT 2011
Year: 2011

A coding scheme based on irregular low-density parity-check (LDPC) codes is proposed to send secret messages from a source over the Gaussian wiretap channel to a destination in the presence of a wiretapper, with the restriction that the source can send only binary phase-shift keyed (BPSK) symbols. The secrecy performance of the proposed coding scheme is measured by the secret message rate through the wiretap channel as well as the equivocation rate about the message at the wiretapper. A code search procedure is suggested to obtain irregular LDPC codes that achieve good secrecy performance in such context.
Mixing, Ergodic, and Nonergodic Processes with Rapidly Growing Information between Blocks
Venue: arXiv cs.IT 2011
Year: 2011

We construct mixing processes over an infinite alphabet and ergodic processes over a finite alphabet for which Shannon mutual information between adjacent blocks of length $n$ grows as $n^β$, where $β\in(0,1)$. The processes are a modification of nonergodic Santa Fe processes, which were introduced in the context of natural language modeling. The rates of mutual information for the latter processes are alike and also established in this paper. As an auxiliary result, it is shown that infinite direct products of mixing processes are also mixing.
Software is a directed multigraph (and so is software process)
Venue: arXiv cs.SE 2011
Year: 2011

For a software system, its architecture is typically defined as the fundamental organization of the system incorporated by its components, their relationships to one another and their environment, and the principles governing their design. If contributed to by the artifacts coresponding to engineering processes that govern the system's evolution, the definition gets natually extended into the architecture of software and software process. Obviously, as long as there were no software systems, managing their architecture was no problem at all; when there were only small systems, managing their architecture became a mild problem; and now we have gigantic software systems, and managing their architecture has become an equally gigantic problem (to paraphrase Edsger Dijkstra). In this paper we propose a simple, yet we believe effective, model for organizing architecture of software systems. First of all we postulate that only a hollistic approach that supports continuous integration and verification for all software and software process architectural artifacts is the one worth taking. Next we indicate a graph-based model that not only allows collecting and maintaining the architectural knowledge in respect to both software and software process, but allows to conveniently create various quantitive metric to asses their respective quality or maturity. Such model is actually independent of the development methodologies that are currently in-use, that is it could well be applied for projects managed in an adaptive, as well as in a formal approach. Eventually we argue that the model could actually be implemented by already existing tools, in particular graph databases are a convenient implementation of architectural repository.
Probabilistically Safe Vehicle Control in a Hostile Environment
Venue: arXiv cs.SY 2011
Year: 2011

In this paper we present an approach to control a vehicle in a hostile environment with static obstacles and moving adversaries. The vehicle is required to satisfy a mission objective expressed as a temporal logic specification over a set of properties satisfied at regions of a partitioned environment. We model the movements of adversaries in between regions of the environment as Poisson processes. Furthermore, we assume that the time it takes for the vehicle to traverse in between two facets of each region is exponentially distributed, and we obtain the rate of this exponential distribution from a simulator of the environment. We capture the motion of the vehicle and the vehicle updates of adversaries distributions as a Markov Decision Process. Using tools in Probabilistic Computational Tree Logic, we find a control strategy for the vehicle that maximizes the probability of accomplishing the mission objective. We demonstrate our approach with illustrative case studies.
Modelling dynamic route choice of pedestrians to assess the criticality of building evacuation
Venue: arXiv cs.OH 2011
Year: 2011

This paper presents an event-driven way finding algorithm for pedestrians in an evacuation scenario, which operates on a graph-based structure. The motivation of each pedestrian is to leave the facility. The events used to redirect pedestrians include the identification of a jam situation and/or identification of a better route than the current. This study considers two types of pedestrians: familiar and unfamiliar with the facility. Four strategies are modelled to cover those groups. The modelled strategies are the shortest path (local and global); They are combined with a quickest path approach, which is based on an observation principle. In the quickest path approach, pedestrians take their decisions based on the observed environment and are routed dynamically in the network using an appropriate cost benefit analysis function. The dynamic modelling of route choice with different strategies and types of pedestrians considers the manifold of in uences which appears in the real system and raises questions about the criticality of an evacuation process. To address this question criteria are elaborated. The criteria we focus on in this contribution are the evacuation time, the individual times spent in jam, the jam size evolution and the overall jam size itself. The in uences of the different strategies on those evaluation criteria are investigated. The sensibility of the system to disturbances (e.g. broken escape route) is also analysed. Keywords: pedestrian dynamics, routing, quickest path, evacuation, jam, critical state
Difference-Huffman Coding of Multidimensional Databases
Venue: arXiv cs.DB 2011
Year: 2011

A new compression method called difference-Huffman coding (DHC) is introduced in this paper. It is verified empirically that DHC results in a smaller multidimensional physical representation than those for other previously published techniques (single count header compression, logical position compression, base-offset compression and difference sequence compression). The article examines how caching influences the expected retrieval time of the multidimensional and table representations of relations. A model is proposed for this, which is then verified with empirical data. Conclusions are drawn, based on the model and the experiment, about when one physical representation outperforms another in terms of retrieval time. Over the tested range of available memory, the performance for the multidimensional representation was always much quicker than for the table representation.
Rendering of 3D Dynamic Virtual Environments
Venue: arXiv cs.GR 2011
Year: 2011

In this paper we present a framework for the rendering of dynamic 3D virtual environments which can be integrated in the development of videogames. It includes methods to manage sounds and particle effects, paged static geometries, the support of a physics engine and various input systems. It has been designed with a modular structure to allow future expansions. We exploited some open-source state-of-the-art components such as OGRE, PhysX, ParticleUniverse, etc.; all of them have been properly integrated to obtain peculiar physical and environmental effects. The stand-alone version of the application is fully compatible with Direct3D and OpenGL APIs and adopts OpenAL APIs to manage audio cards. Concluding, we devised a showcase demo which reproduces a dynamic 3D environment, including some particular effects: the alternation of day and night infuencing the lighting of the scene, the rendering of terrain, water and vegetation, the reproduction of sounds and atmospheric agents.
Stratified B-trees and versioning dictionaries
Venue: arXiv cs.DS 2011
Year: 2011

A classic versioned data structure in storage and computer science is the copy-on-write (CoW) B-tree -- it underlies many of today's file systems and databases, including WAFL, ZFS, Btrfs and more. Unfortunately, it doesn't inherit the B-tree's optimality properties; it has poor space utilization, cannot offer fast updates, and relies on random IO to scale. Yet, nothing better has been developed since. We describe the `stratified B-tree', which beats all known semi-external memory versioned B-trees, including the CoW B-tree. In particular, it is the first versioned dictionary to achieve optimal tradeoffs between space, query and update performance.
Design and analysis of continuous hybrid differentiator
Venue: arXiv cs.SY 2011
Year: 2011

In this paper, a continuous hybrid differentiator is presented based on a strong Lyapunov function. The differentiator design can not only reduce sufficiently chattering phenomenon of derivative estimation by introducing a perturbation parameter, but also the dynamical performances are improved by adding linear correction terms to the nonlinear ones. Moreover, strong robustness ability is obtained by integrating sliding mode items and the linear filter. Frequency analysis is applied to compare the hybrid continuous differentiator with sliding mode differentiator. The merits of the continuous hybrid differentiator include the excellent dynamical performances, restraining noises sufficiently, and avoiding the chattering phenomenon.
On the gradual deployment of random pairwise key distribution schemes (Extended Version)
Venue: arXiv cs.CR 2011
Year: 2011

In the context of wireless sensor networks, the pairwise key distribution scheme of Chan et al. has several advantages over other key distribution schemes including the original scheme of Eschenauer and Gligor. However, this offline pairwise key distribution mechanism requires that the network size be set in advance, and involves all sensor nodes simultaneously. Here, we address this issue by describing an implementation of the pairwise scheme that supports the gradual deployment of sensor nodes in several consecutive phases. We discuss the key ring size needed to maintain the secure connectivity throughout all the deployment phases. In particular we show that the number of keys at each sensor node can be taken to be $O(\log n)$ in order to achieve secure connectivity (with high probability).
Anytime Reliable Codes for Stabilizing Plants over Erasure Channels
Venue: arXiv cs.SY 2011
Year: 2011

The problem of stabilizing an unstable plant over a noisy communication link is an increasingly important one that arises in problems of distributed control and networked control systems. Although the work of Schulman and Sahai over the past two decades, and their development of the notions of "tree codes" and "anytime capacity", provides the theoretical framework for studying such problems, there has been scant practical progress in this area because explicit constructions of tree codes with efficient encoding and decoding did not exist. To stabilize an unstable plant driven by bounded noise over a noisy channel one needs real-time encoding and real-time decoding and a reliability which increases exponentially with delay, which is what tree codes guarantee. We prove the existence of linear tree codes with high probability and, for erasure channels, give an explicit construction with an expected encoding and decoding complexity that is constant per time instant. We give sufficient conditions on the rate and reliability required of the tree codes to stabilize vector plants and argue that they are asymptotically tight. This work takes a major step towards controlling plants over noisy channels, and we demonstrate the efficacy of the method through several examples.
An Improved Efficient Key Distribution Mechanism for Large-Scale Heterogeneous Mobile Sensor Networks
Venue: arXiv cs.CR 2011
Year: 2011

Due to resource constraints of the sensor nodes, traditional public key cryptographic techniques are not feasible in most sensor network architectures. Several symmetric key distribution mechanisms are proposed for establishing pairwise keys between sensor nodes in sensor networks, but most of them are not scalable and also are not much suited for mobile sensor networks because they incur much communication as well as computational overheads. Moreover, these schemes are either vulnerable to a small number of compromised sensor nodes or involve expensive protocols for establishing keys. In this paper, we introduce a new scheme for establishing keys between sensor nodes with the help of additional high-end sensor nodes, called the auxiliary nodes. Our scheme provides unconditional security against sensor node captures and high network connectivity. In addition, our scheme requires minimal storage requirement for storing keys mainly due to only a single key before deployment in each node in the sensor network, supports efficiently addition of new nodes after initial deployment and also works for any deployment topology.
Community Detection via Semi-Synchronous Label Propagation Algorithms
Venue: arXiv cs.SI 2011
Year: 2011

A recently introduced novel community detection strategy is based on a label propagation algorithm (LPA) which uses the diffusion of information in the network to identify communities. Studies of LPAs showed that the strategy is effective in finding a good community structure. Label propagation step can be performed in parallel on all nodes (synchronous model) or sequentially (asynchronous model); both models present some drawback, e.g., algorithm termination is nor granted in the first case, performances can be worst in the second case. In this paper, we present a semi-synchronous version of LPA which aims to combine the advantages of both synchronous and asynchronous models. We prove that our models always converge to a stable labeling. Moreover, we experimentally investigate the effectiveness of the proposed strategy comparing its performance with the asynchronous model both in terms of quality, efficiency and stability. Tests show that the proposed protocol does not harm the quality of the partitioning. Moreover it is quite efficient; each propagation step is extremely parallelizable and it is more stable than the asynchronous model, thanks to the fact that only a small amount of randomization is used by our proposal.