OpenRaiser/Intern-Atlas huggingface dataset:
Optimizing data collection for object tracking in wireless sensor networks
Venue: arXiv cs.NI 2013
Year: 2013

In this paper some modifications are proposed to optimize an algorithm of object tracking in wireless sensor network (WSN). The task under consideration is to control movement of a mobile sink, which has to reach a target in the shortest possible time. Utilization of the WSN resources is optimized by transferring only selected data readings (target locations) to the mobile sink. Simulations were performed to evaluate the proposed modifications against state-of-the-art methods. The obtained results show that the presented tracking algorithm allows for substantial reduction of data collection costs with no significant increase in the amount of time that it takes to catch the target.
Educating Programmers: A Reflection on Barriers to Deliberate Practice
Venue: arXiv cs.CY 2013
Year: 2013

Programming is a craft which often demands that learners engage in a significantly high level of individual practice and experimentation in order to acquire basic competencies. However, practice behaviours can be undermined during the early stages of instruction. This is often the result of seemingly trivial misconceptions that, when left unchecked, create cognitive-affective barriers. These interact with learners' self-beliefs, potentially inducing affective states that inhibit practice. This paper questions how to design a learning environment that can address this issue. It is proposed that analytical and adaptable approaches, which could include soft scaffolding, ongoing detailed informative feedback and a focus on self-enhancement alongside skill development, can help overcome such barriers.
Physical-Layer Security with Multiuser Scheduling in Cognitive Radio Networks
Venue: arXiv cs.IT 2013
Year: 2013

In this paper, we consider a cognitive radio network that consists of one cognitive base station (CBS) and multiple cognitive users (CUs) in the presence of multiple eavesdroppers, where CUs transmit their data packets to CBS under a primary user's quality of service (QoS) constraint while the eavesdroppers attempt to intercept the cognitive transmissions from CUs to CBS. We investigate the physical-layer security against eavesdropping attacks in the cognitive radio network and propose the user scheduling scheme to achieve multiuser diversity for improving the security level of cognitive transmissions with a primary QoS constraint. Specifically, a cognitive user (CU) that satisfies the primary QoS requirement and maximizes the achievable secrecy rate of cognitive transmissions is scheduled to transmit its data packet. For the comparison purpose, we also examine the traditional multiuser scheduling and the artificial noise schemes. We analyze the achievable secrecy rate and intercept probability of the traditional and proposed multiuser scheduling schemes as well as the artificial noise scheme in Rayleigh fading environments. Numerical results show that given a primary QoS constraint, the proposed multiuser scheduling scheme generally outperforms the traditional multiuser scheduling and the artificial noise schemes in terms of the achievable secrecy rate and intercept probability. In addition, we derive the diversity order of the proposed multiuser scheduling scheme through an asymptotic intercept probability analysis and prove that the full diversity is obtained by using the proposed multiuser scheduling.
Automated Change Detection and Reactive Clustering in Multivariate Streaming Data
Venue: arXiv cs.DB 2013
Year: 2013

Many automated systems need the capability of automatic change detection without the given detection threshold. This paper presents an automated change detection algorithm in streaming multivariate data. Two overlapping windows are used to quantify the changes. While a window is used as the reference window from which the clustering is created, the other called the current window captures the newly incoming data points. A newly incoming data point can be considered a change point if it is not a member of any cluster. As our clustering-based change detector does not require detection threshold, it is an automated detector. Based on this change detector, we propose a reactive clustering algorithm for streaming data. Our empirical results show that, our clustering-based change detector works well with multivariate streaming data. The detection accuracy depends on the number of clusters in the reference window, the window width.
Networks of Innovation in 3D Printing
Venue: arXiv cs.HC 2013
Year: 2013

Innovation inside companies is difficult to see. But an emerging online community of inventors who publicly post 3D CAD drawings of their work provide a way to observe - and perhaps amplify - innovation. In this paper we analyze the network structure of Thingiverse, a website oriented toward 3D printing. This form of printing blurs the line between creating information and manufacturing objects: drawings can be sent to devices that build 3D objects out of many materials, including resin, ceramics, and metal. As an exploratory study, we analyzed the structure of Thingiverse links. Our results suggest that analysis of remix network structure may provide ways of tracing innovation processes and detecting the emergence of new ideas, combination of disparate ideas.
Graphs with no 7-wheel subdivision
Venue: arXiv cs.DM 2013
Year: 2013

The subgraph homeomorphism problem, SHP($H$), has been shown to be polynomial-time solvable for any fixed pattern graph $H$, but practical algorithms have been developed only for a few specific pattern graphs. Among these are the wheels with four, five, and six spokes. This paper examines the subgraph homeomorphism problem where the pattern graph is a wheel with seven spokes, and gives a result that describes graphs with no $W_{7}$-subdivision, showing how they can be built up, using certain operations, from smaller `pieces' that meet certain conditions. We also discuss algorithmic aspects of the problem.
Search strategies for developing characterizations of graphs without small wheel subdivisions
Venue: arXiv cs.DM 2013
Year: 2013

Practical algorithms for solving the Subgraph Homeomorphism Problem are known for only a few small pattern graphs: among these are the wheel graphs with four, five, six, and seven spokes. The length and difficulty of the proofs leading to these algorithms increase greatly as the size of the pattern graph increases. Proving a result for the wheel with six spokes requires extensive case analysis on many small graphs, and even more such analysis is needed for the wheel with seven spokes. This paper describes algorithms and programs used to automate the generation and testing of the graphs that arise as cases in these proofs. The main algorithm given may be useful in a more general context, for developing other characterizations of SHP-related properties.
Q-Gaussian Swarm Quantum Particle Intelligence on Predicting Global Minimum of Potential Energy Function
Venue: arXiv cs.NE 2013
Year: 2013

We present a newly developed -Gaussian Swarm Quantum-like Particle Optimization (q-GSQPO) algorithm to determine the global minimum of the potential energy function. Swarm Quantum-like Particle Optimization (SQPO) algorithms have been derived using different attractive potential fields to represent swarm particles moving in a quantum environment, where the one which uses a harmonic oscillator potential as attractive field is considered as an improved version. In this paper, we propose a new SQPO that uses -Gaussian probability density function for the attractive potential field (q-GSQPO) rather than Gaussian one (GSQPO) which corresponds to harmonic potential. The performance of the q-GSQPO is compared against the GSQPO. The new algorithm outperforms the GSQPO on most of the time in convergence to the global optimum by increasing the efficiency of sampling the phase space and avoiding the premature convergence to local minima. Moreover, the computational efforts were comparable for both algorithms. We tested the algorithm to determine the lowest energy configurations of a particle moving in a 2, 5, 10, and 50 dimensional spaces.
On the effect of the IO-substitution on the Parikh image of semilinear AFLs
Venue: arXiv cs.FL 2013
Year: 2013

Back in the 80s, the class of mildly context-sensitive formalisms was introduced so as to capture the syntax of natural languages. While the languages generated by such formalisms are constrained by the constant-growth property, the most well-known and used mildly-context sensitive formalisms, like tree-adjoining grammars or multiple context-free grammars, generate languages which verify the stronger property of being semilinear. In (Bourreau et al., 2012), the operation of IO-ubstitution was created so as to exhibit mildly context-sensitive classes of languages which are not semilinear, although they verify the constant-growth property. In the present article, we extend the notion of semilinearity, and characterise the Parikh image of the IO-MCFLs (i.e. languages which belong to the closure of MCFLs under IO-subsitution) as universally-linear. Based on this result and on the work of Fischer on macro-grammars, we then show IO-MCFLs are not closed under inverse homomorphism, which proves that the family of IO-MCFLs is not an abstract family of languages.
A Parallel SGD method with Strong Convergence
Venue: arXiv cs.LG 2013
Year: 2013

This paper proposes a novel parallel stochastic gradient descent (SGD) method that is obtained by applying parallel sets of SGD iterations (each set operating on one node using the data residing in it) for finding the direction in each iteration of a batch descent method. The method has strong convergence properties. Experiments on datasets with high dimensional feature spaces show the value of this method.
Automatic Airspace Sectorisation: A Survey
Venue: arXiv cs.OH 2013
Year: 2013

Airspace sectorisation provides a partition of a given airspace into sectors, subject to geometric constraints and workload constraints, so that some cost metric is minimised. We survey the algorithmic aspects of methods for automatic airspace sectorisation, for an intended readership of experts on air traffic management.
Edge covering with budget constrains
Venue: arXiv cs.DS 2013
Year: 2013

We study two related problems: finding a set of k vertices and minimum number of edges (kmin) and finding a graph with at least m' edges and minimum number of vertices (mvms). Goldschmidt and Hochbaum \cite{GH97} show that the mvms problem is NP-hard and they give a 3-approximation algorithm for the problem. We improve \cite{GH97} by giving a ratio of 2. A 2(1+ε)-approximation for the problem follows from the work of Carnes and Shmoys \cite{CS08}. We improve the approximation ratio to 2. algorithm for the problem. We show that the natural LP for \kmin has an integrality gap of 2-o(1). We improve the NP-completeness of \cite{GH97} by proving the pronlem are APX-hard unless a well-known instance of the dense k-subgraph admits a constant ratio. The best approximation guarantee known for this instance of dense k-subgraph is O(n^{2/9}) \cite{BCCFV}. We show that for any constant ρ>1, an approximation guarantee of ρfor the \kmin problem implies a ρ(1+o(1)) approximation for \mwms. Finally, we define we give an exact algorithm for the density version of kmin.
On the Distributed Construction of a Collision-Free Schedule in WLANs
Venue: arXiv cs.NI 2013
Year: 2013

In wireless local area networks (WLANs), a media access protocol arbitrates access to the channel. In current IEEE 802.11 WLANs, carrier sense multiple access with collision avoidance (CSMA/CA) is used. Carrier sense multiple access with enhanced collision avoidance (CSMA/ECA) is a subtle variant of the well-known CSMA/CA algorithm that offers substantial performance benefits. CSMA/ECA significantly reduces the collision probability and, under certain conditions, leads to a completely collision-free schedule. The only difference between CSMA/CA and CSMA/ECA is that the latter uses a deterministic backoff after successful transmissions. This deterministic backoff is a constant and is the same for all the stations. The first part of the paper is of tutorial nature, offering an introduction to the basic operation of CSMA/ECA and describing the benefits of this approach in a qualitative manner. The second part of the paper surveys related contributions, briefly summarizing the main challenges and potential solutions, and also introducing variants and derivatives of CSMA/ECA.
An Intuitive Design Approach For Implementing Real Time Audio Effects
Venue: arXiv cs.SD 2013
Year: 2013

Audio effect implementation on random musical signal is a basic application of digital signal processors. In this paper, the compatibility features of MATLAB R2008a with Code Composer Studio 3.3 has been exploited to develop Simulink models which when emulated on TMS320C6713 DSK generate real time audio effects. Each design has been done by two different asynchronous scheduling techniques: (i) Idle task Scheduling and (ii) DSP/BIOS task Scheduling. A basic COCOMO analysis has been done for the generated code to justify the industrial viability of this design approach. KEYWORDS: Musical signal processing, Real time Audio effects, Echo, Stress Generation, Reverberation, Reverberated Chorus, Real Time Scheduling.
Two automated techniques for analyzing and debugging Mpi-based programs
Venue: arXiv cs.PL 2013
Year: 2013

Message Passing Interface (MPI) is the most commonly used paradigm in writing parallel programs since it can be employed not only within a single processing node but also across several connected ones. Data flow analysis concepts, techniques and tools are needed to understand and analyze MPI-based programs to detect bugs arise in these programs. In this paper we propose two automated techniques to analyze and debug MPI-based programs source codes.
On the Efficiency of the Walrasian Mechanism
Venue: arXiv cs.GT 2013
Year: 2013

Central results in economics guarantee the existence of efficient equilibria for various classes of markets. An underlying assumption in early work is that agents are price-takers, i.e., agents honestly report their true demand in response to prices. A line of research in economics, initiated by Hurwicz (1972), is devoted to understanding how such markets perform when agents are strategic about their demands. This is captured by the \emph{Walrasian Mechanism} that proceeds by collecting reported demands, finding clearing prices in the \emph{reported} market via an ascending price tâtonnement procedure, and returns the resulting allocation. Similar mechanisms are used, for example, in the daily opening of the New York Stock Exchange and the call market for copper and gold in London. In practice, it is commonly observed that agents in such markets reduce their demand leading to behaviors resembling bargaining and to inefficient outcomes. We ask how inefficient the equilibria can be. Our main result is that the welfare of every pure Nash equilibrium of the Walrasian mechanism is at least one quarter of the optimal welfare, when players have gross substitute valuations and do not overbid. Previous analysis of the Walrasian mechanism have resorted to large market assumptions to show convergence to efficiency in the limit. Our result shows that approximate efficiency is guaranteed regardless of the size of the market.
SolarStat: Modeling Photovoltaic Sources through Stochastic Markov Processes
Venue: arXiv cs.OH 2013
Year: 2013

In this paper, we present a methodology and a tool to derive simple but yet accurate stochastic Markov processes for the description of the energy scavenged by outdoor solar sources. In particular, we target photovoltaic panels with small form factors, as those exploited by embedded communication devices such as wireless sensor nodes or, concerning modern cellular system technology, by small-cells. Our models are especially useful for the theoretical investigation and the simulation of energetically self-sufficient communication systems including these devices. The Markov models that we derive in this paper are obtained from extensive solar radiation databases, that are widely available online. Basically, from hourly radiance patterns, we derive the corresponding amount of energy (current and voltage) that is accumulated over time, and we finally use it to represent the scavenged energy in terms of its relevant statistics. Toward this end, two clustering approaches for the raw radiance data are described and the resulting Markov models are compared against the empirical distributions. Our results indicate that Markov models with just two states provide a rough characterization of the real data traces. While these could be sufficiently accurate for certain applications, slightly increasing the number of states to, e.g., eight, allows the representation of the real energy inflow process with an excellent level of accuracy in terms of first and second order statistics. Our tool has been developed using Matlab(TM) and is available under the GPL license at[1].
Modeling and Verification of Infinite Systems with Resources
Venue: arXiv cs.LO 2013
Year: 2013

We consider formal verification of recursive programs with resource consumption. We introduce prefix replacement systems with non-negative integer counters which can be incremented and reset to zero as a formal model for such programs. In these systems, we investigate bounds on the resource consumption for reachability questions. Motivated by this question, we introduce relational structures with resources and a quantitative first-order logic over these structures. We define resource automatic structures as a subclass of these structures and provide an effective method to compute the semantics of the logic on this subclass. Subsequently, we use this framework to solve the bounded reachability problem for resource prefix replacement systems. We achieve this result by extending the well-known saturation method to annotated prefix replacement systems. Finally, we provide a connection to the study of the logic cost-WMSO.
A Chemistry-Inspired Framework for Achieving Consensus in Wireless Sensor Networks
Venue: arXiv cs.DC 2013
Year: 2013

The aim of this paper is to show how simple interaction mechanisms, inspired by chemical systems, can provide the basic tools to design and analyze a mathematical model for achieving consensus in wireless sensor networks, characterized by balanced directed graphs. The convergence and stability of the model are first proven by using new mathematical tools, which are borrowed directly from chemical theory, and then validated by means of simulation results, for different network topologies and number of sensors. The underlying chemical theory is also used to derive simple interaction rules that may account for practical issues, such as the estimation of the number of neighbors and the robustness against perturbations. Finally, the proposed chemical solution is validated under real-world conditions by means of a four-node hardware implementation where the exchange of information among nodes takes place in a distributed manner (with no need for any admission control and synchronism procedure), simply relying on the transmission of a pulse whose rate is proportional to the state of each sensor.
Constrained Codes for Joint Energy and Information Transfer
Venue: arXiv cs.IT 2013
Year: 2013

In various wireless systems, such as sensor RFID networks and body area networks with implantable devices, the transmitted signals are simultaneously used both for information transmission and for energy transfer. In order to satisfy the conflicting requirements on information and energy transfer, this paper proposes the use of constrained run-length limited (RLL) codes in lieu of conventional unconstrained (i.e., random-like) capacity-achieving codes. The receiver's energy utilization requirements are modeled stochastically, and constraints are imposed on the probabilities of battery underflow and overflow at the receiver. It is demonstrated that the codewords' structure afforded by the use of constrained codes enables the transmission strategy to be better adjusted to the receiver's energy utilization pattern, as compared to classical unstructured codes. As a result, constrained codes allow a wider range of trade-offs between the rate of information transmission and the performance of energy transfer to be achieved.
From Theory to Practice: Plug and Play with Succinct Data Structures
Venue: arXiv cs.DS 2013
Year: 2013

Engineering efficient implementations of compact and succinct structures is a time-consuming and challenging task, since there is no standard library of easy-to- use, highly optimized, and composable components. One consequence is that measuring the practical impact of new theoretical proposals is a difficult task, since older base- line implementations may not rely on the same basic components, and reimplementing from scratch can be very time-consuming. In this paper we present a framework for experimentation with succinct data structures, providing a large set of configurable components, together with tests, benchmarks, and tools to analyze resource requirements. We demonstrate the functionality of the framework by recomposing succinct solutions for document retrieval.
Multi-target Radar Detection within a Sparsity Framework
Venue: arXiv cs.IT 2013
Year: 2013

Traditional radar detection schemes are typically studied for single target scenarios and they can be non-optimal when there are multiple targets in the scene. In this paper, we develop a framework to discuss multi-target detection schemes with sparse reconstruction techniques that is based on the Neyman-Pearson criterion. We will describe an initial result in this framework concerning false alarm probability with LASSO as the sparse reconstruction technique. Then, several simulations validating this result will be discussed. Finally, we describe several research avenues to further pursue this framework.
How Does Kanban Impact Communication and Collaboration in Software Engineering Teams?
Venue: arXiv cs.SE 2013
Year: 2013

Highly iterative development processes such as Kanban have gained significant importance in industry. However, the impact of such processes on team collaboration and communication is widely unknown. In this paper, we analyze how the Kanban process aids software team's behaviours -- in particular, communication and collaboration. The team under study developed a mobile payment software product in six iterations over seven weeks. The data were collected by a questionnaire, repeated at the end of each iteration. The results indicate that Kanban has a positive effect at the beginning to get the team working together to identify and coordinate the work. Later phases, when the team members have established good rapport among them, the importance for facilitating team collaboration could not be shown. Results also indicate that Kanban helps team members to collectively identify and surface the missing tasks to keep the pace of the development harmonized across the whole team, resulting into increased collaboration. Besides presenting the study and the results, the article gives an outlook on future work.