OpenRaiser/Intern-Atlas huggingface dataset:
Together we stand, Together we fall, Together we win: Dynamic Team Formation in Massive Open Online Courses
Venue: arXiv cs.SI 2014
Year: 2014

Massive Open Online Courses (MOOCs) offer a new scalable paradigm for e-learning by providing students with global exposure and opportunities for connecting and interacting with millions of people all around the world. Very often, students work as teams to effectively accomplish course related tasks. However, due to lack of face to face interaction, it becomes difficult for MOOC students to collaborate. Additionally, the instructor also faces challenges in manually organizing students into teams because students flock to these MOOCs in huge numbers. Thus, the proposed research is aimed at developing a robust methodology for dynamic team formation in MOOCs, the theoretical framework for which is grounded at the confluence of organizational team theory, social network analysis and machine learning. A prerequisite for such an undertaking is that we understand the fact that, each and every informal tie established among students offers the opportunities to influence and be influenced. Therefore, we aim to extract value from the inherent connectedness of students in the MOOC. These connections carry with them radical implications for the way students understand each other in the networked learning community. Our approach will enable course instructors to automatically group students in teams that have fairly balanced social connections with their peers, well defined in terms of appropriately selected qualitative and quantitative network metrics.
The Power of an Example: Hidden Set Size Approximation Using Group Queries and Conditional Sampling
Venue: arXiv cs.DS 2014
Year: 2014

We study a basic problem of approximating the size of an unknown set $S$ in a known universe $U$. We consider two versions of the problem. In both versions the algorithm can specify subsets $T\subseteq U$. In the first version, which we refer to as the group query or subset query version, the algorithm is told whether $T\cap S$ is non-empty. In the second version, which we refer to as the subset sampling version, if $T\cap S$ is non-empty, then the algorithm receives a uniformly selected element from $T\cap S$. We study the difference between these two versions under different conditions on the subsets that the algorithm may query/sample, and in both the case that the algorithm is adaptive and the case where it is non-adaptive. In particular we focus on a natural family of allowed subsets, which correspond to intervals, as well as variants of this family.
Uniform and Piece-wise Uniform Fields in Memristor Models
Venue: arXiv cs.ET 2014
Year: 2014

The Strukov model was the phenomenological model that accompanied the announcement of the first recognised physical instantiation of the memristor and, as such, it has been widely used. This model described the motion of a boundary, $w$, between two types of inter-converting material, $R_{\mathrm{off}}$ and $R_{\mathrm{on}}$, seemingly under a uniform field across the entire device. In fact, what was intended was a field with a discontinuity at $w$, that was uniform between $0<x<w$. In this paper we show that the discontinuity is required for the Strukov model derivation to be completed, and thus the derivation as given does not describe a situation with a uniform field across the entire device. The discontinuity can be described as a Heaviside function, $H$, located on $w$, for which there are three common single-valued approximations for $H(w)$. The Strukov model as intended includes an approximation for the Heaviside function (the field is taken to be the same as that across the $R_{\mathrm{on}}$ part of the device). We compare approximations and give solutions. We then extend the description of the field to a more-realistic continuously varying sigmoidal transition between two uniform fields and demonstrate that the centro-symmetric approximation model (taking the field as being the average of the fields across $R_{\mathrm{on}}$ and $R_{\mathrm{off}}$) is a better single-point model of that situation: the other two approximations over or underestimate the field.
A Structural Query System for Han Characters
Venue: arXiv cs.CL 2014
Year: 2014

The IDSgrep structural query system for Han character dictionaries is presented. This system includes a data model and syntax for describing the spatial structure of Han characters using Extended Ideographic Description Sequences (EIDSes) based on the Unicode IDS syntax; a language for querying EIDS databases, designed to suit the needs of font developers and foreign language learners; a bit vector index inspired by Bloom filters for faster query operations; a freely available implementation; and format translation from popular third-party IDS and XML character databases. Experimental results are included, with a comparison to other software used for similar applications.
IMP Science Gateway: from the Portal to the Hub of Virtual Experimental Labs in Materials Science
Venue: arXiv cs.CE 2014
Year: 2014

"Science gateway" (SG) ideology means a user-friendly intuitive interface between scientists (or scientific communities) and different software components + various distributed computing infrastructures (DCIs) (like grids, clouds, clusters), where researchers can focus on their scientific goals and less on peculiarities of software/DCI. "IMP Science Gateway Portal" (http://scigate.imp.kiev.ua) for complex workflow management and integration of distributed computing resources (like clusters, service grids, desktop grids, clouds) is presented. It is created on the basis of WS-PGRADE and gUSE technologies, where WS-PGRADE is designed for science workflow operation and gUSE - for smooth integration of available resources for parallel and distributed computing in various heterogeneous distributed computing infrastructures (DCI). The typical scientific workflows with possible scenarios of its preparation and usage are presented. Several typical use cases for these science applications (scientific workflows) are considered for molecular dynamics (MD) simulations of complex behavior of various nanostructures (nanoindentation of graphene layers, defect system relaxation in metal nanocrystals, thermal stability of boron nitride nanotubes, etc.). The user experience is analyzed in the context of its practical applications for MD simulations in materials science, physics and nanotechnologies with available heterogeneous DCIs. In conclusion, the "science gateway" approach - workflow manager (like WS-PGRADE) + DCI resources manager (like gUSE)- gives opportunity to use the SG portal (like "IMP Science Gateway Portal") in a very promising way, namely, as a hub of various virtual experimental labs (different software components + various requirements to resources) in the context of its practical MD applications in materials science, physics, chemistry, biology, and nanotechnologies.
Converging Work-Talk Patterns in Online Task-Oriented Communities
Venue: arXiv cs.SE 2014
Year: 2014

Much of what we do is accomplished by working collaboratively with others, and a large portion of our lives are spent working and talking; the patterns embodied in the alternation of working and talking can provide much useful insight into task-oriented social behaviors. The available electronic traces of the different kinds of human activities in online communities are an empirical goldmine that can enable the holistic study and understanding of these social systems. Open Source Software projects are prototypical examples of collaborative, task-oriented communities, depending on volunteers for high-quality work. Here, we use sequence analysis methods to identify the work-talk patterns of software developers in these online communities. We find that software developers prefer to persist in same kinds of activities, i.e., a string of work activities followed by a string of talk activities and so forth, rather than switch them frequently; this tendency strengthens with time, suggesting that developers become more efficient, and can work longer with fewer interruptions. This process is accompanied by the formation of community culture: developers' patterns in the same communities get closer with time while different communities get relatively more different. The emergence of community culture is apparently driven by both "talk" and "work". Finally, we also find that workers with good balance between "work" and "talk" tend to produce just as much work as those that focus strongly on "work"; however, the former appear to be more likely to continue to be active contributors in the communities.
Certificates in Data Structures
Venue: arXiv cs.DS 2014
Year: 2014

We study certificates in static data structures. In the cell-probe model, certificates are the cell probes which can uniquely identify the answer to the query. As a natural notion of nondeterministic cell probes, lower bounds for certificates in data structures immediately imply deterministic cell-probe lower bounds. In spite of this extra power brought by nondeterminism, we prove that two widely used tools for cell-probe lower bounds: richness lemma of Miltersen et al. and direct-sum richness lemma of Patrascu and Thorup, both hold for certificates in data structures with even better parameters. Applying these lemmas and adopting existing reductions, we obtain certificate lower bounds for a variety of static data structure problems. These certificate lower bounds are at least as good as the highest known cell-probe lower bounds for the respective problems. In particular, for approximate near neighbor (ANN) problem in Hamming distance, our lower bound improves the state of the art. When the space is strictly linear, our lower bound for ANN in d-dimensional Hamming space becomes t=Omega(d), which along with the recent breakthrough for polynomial evaluation of Larsen, are the only two t=Omega(d) lower bounds ever proved for any problems in the cell-probe model.
An Effective Round Robin Algorithm using Min-Max Dispersion Measure
Venue: arXiv cs.OS 2014
Year: 2014

Round Robin (RR) scheduling algorithm is a preemptive scheduling algorithm. It is designed especially for time sharing Operating System (OS). In RR scheduling algorithm the CPU switches between the processes when the static Time Quantum (TQ) expires. RR scheduling algorithm is considered as the most widely used scheduling algorithm in research because the TQ is equally shared among the processes. In this paper a newly proposed variant of RR algorithm called Min-Max Round Robin (MMRR) scheduling algorithm is presented. The idea of this MMRR is to make the TQ repeatedly adjusted using Min-Max dispersion measure in accordance with remaining CPU burst time. Our experimental analysis shows that MMRR performs much better than RR algorithm in terms of average turnaround time, average waiting time and number of context switches.
Linear Time LexDFS on Cocomparability Graphs
Venue: arXiv cs.DS 2014
Year: 2014

Lexicographic depth first search (LexDFS) is a graph search protocol which has already proved to be a powerful tool on cocomparability graphs. Cocomparability graphs have been well studied by investigating their complements (comparability graphs) and their corresponding posets. Recently however LexDFS has led to a number of elegant polynomial and near linear time algorithms on cocomparability graphs when used as a preprocessing step [2, 3, 11]. The nonlinear runtime of some of these results is a consequence of complexity of this preprocessing step. We present the first linear time algorithm to compute a LexDFS cocomparability ordering, therefore answering a problem raised in [2] and helping achieve the first linear time algorithms for the minimum path cover problem, and thus the Hamilton path problem, the maximum independent set problem and the minimum clique cover for this graph family.
Service-Constraint Based Truthful Incentive Mechanisms for Crowd Sensing
Venue: arXiv cs.NI 2014
Year: 2014

Crowd sensing is a new paradigm which leverages the pervasive smartphones to efficiently collect and upload sensing data, enabling numerous novel applications. To achieve good service quality for a crowd sensing application, incentive mechanisms are necessary for attracting more user participation. Most of existing mechanisms apply only for the budget-constraint scenario where the platform (the crowd sensing organizer) has a budget limit. On the contrary, we focus on a different scenario where the platform has a service limit. Based on the offline and online auction model, we consider a general problem: users submit their private profiles to the platform, and the platform aims at selecting a subset of users before a specified deadline for minimizing the total payment while a specific service can be completed. Specially, we design offline and online service-constraint incentive mechanisms for the case where the value function of selected users is monotone submodular. The mechanisms are individual rationality, task feasibility, computational efficiency, truthfulness, consumer sovereignty, constant frugality, and also performs well in practice. Finally, we use extensive simulations to demonstrate the theoretical properties of our mechanisms.
Optimization and design of a laser-cutting machine using delta robot
Venue: arXiv cs.RO 2014
Year: 2014

Industrial high speed laser operations the use of delta parallel robots potentially offers many benefits due to their structural stiffness and limited moving masses. This paper deals with a particular Delta, developed for high speed laser cutting. Parallel delta robot has numerous advantages in comparison with serial robots Higher stiffness and connected with that a lower mass of links the possibility of transporting heavier loads, and higher accuracy. The main drawback is however a smaller workspace. Hence there exists an interest for the research concerning the workspace of robots.In industrial cutting tool maximum do not have more prescribe measurement to cut so that in This paper is oriented to parallel kinematic robots definition description of their specific application of laser cutting comparison of robots made by different producers and determination of velocity and acceleration parameters kinematic analysis inverse and forward kinematic. It brings information about development of Delta robot. The production of laser cutting machines began thirty years ago. The progress was very fast and at present time every year over 3000 laser cutting machines is installed in the world. Laser cutting is one of the largest applications of lasers in metal working industry.
Design of a Low Voltage Class-AB CMOS Super Buffer Amplifier with Sub Threshold and Leakage Control
Venue: arXiv cs.OH 2014
Year: 2014

This paper describes a CMOS analogy voltage supper buffer designed to have extremely low static current Consumption as well as high current drive capability. A new technique is used to reduce the leakage power of class-AB CMOS buffer circuits without affecting dynamic power dissipation. The name of applied technique is TRANSISTOR GATING TECHNIQUE, which gives the high speed buffer with the reduced low power dissipation (1.105%), low leakage and reduced area (3.08%) also. The proposed buffer is simulated at 45nm CMOS technology and the circuit is operated at 3.3V supply[11]. Consumption is comparable to the switching component. Reports indicate that 40% or even higher percentage of the total power consumption is due to the leakage of transistors. This percentage will increase with technology scaling unless effective techniques are introduced to bring leakage under control. This article focuses on circuit optimization and Design automation techniques to accomplish this goal [9].
Structural Interactions and Absorption of Structural Rules in BI Sequent Calculus
Venue: arXiv cs.LO 2014
Year: 2014

Development of a contraction-free BI sequent calculus, be it in the sense of G3i or G4i, has not been successful in literature. We address the open problem by presenting such a sequent system. In fact our calculus involves no structural rules.
Design and considerations of ADC0808 as interleaved ADCs
Venue: arXiv cs.OH 2014
Year: 2014

Here in this paper we are presenting a digital system background technique for correcting the time offset error rate and gain mismatches in a time interleaved analog to digital converter system for N channel communication using 8 bit ADC0808 ICs. A time interleaved A to D converter system is an effective way to implement a high sampling rate ADC with relatively slow circuits. This paper analyses the benefits and derives an upper band on the performance by considering kT/C noise and slewing requirement of the circuit driving the system. In the system, several channel ADCs operate at interleaved sampling times as if they were effectively a single ADC operating at a much higher sampling rate. A timing mismatch calibration technique is proposed that covers linear and non linear channel mismatches, unifies, and extends the channel models. A novel foreground channel mismatch identification method has been developed, which can be used to fully characterize dynamic linear mismatches. A background identification method provides accurate timing mismatch estimates.
Harnessing Bursty Interference in Multicarrier Systems with Feedback
Venue: arXiv cs.IT 2014
Year: 2014

We study parallel symmetric 2-user interference channels when the interference is bursty and feedback is available from the respective receivers. Presence of interference in each subcarrier is modeled as a memoryless Bernoulli random state. The states across subcarriers are drawn from an arbitrary joint distribution with the same marginal probability for each subcarrier and instantiated i.i.d. over time. For the linear deterministic setup, we give a complete characterization of the capacity region. For the setup with Gaussian noise, we give outer bounds and a tight generalized degrees of freedom characterization. We propose a novel helping mechanism which enables subcarriers in very strong interference regime to help in recovering interfered signals for subcarriers in strong and weak interference regimes. Depending on the interference and burstiness regime, the inner bounds either employ the proposed helping mechanism to code across subcarriers or treat the subcarriers separately. The outer bounds demonstrate a connection to a subset entropy inequality by Madiman and Tetali.
Unsupervised Text Extraction from G-Maps
Venue: arXiv cs.CV 2014
Year: 2014

This paper represents an text extraction method from Google maps, GIS maps/images. Due to an unsupervised approach there is no requirement of any prior knowledge or training set about the textual and non-textual parts. Fuzzy CMeans clustering technique is used for image segmentation and Prewitt method is used to detect the edges. Connected component analysis and gridding technique enhance the correctness of the results. The proposed method reaches 98.5% accuracy level on the basis of experimental data sets.
Compressed Sensing Based Direct Conversion Receiver With Interference Reducing Sampling
Venue: arXiv cs.IT 2014
Year: 2014

This paper describes a direct conversion receiver applying compressed sensing with the objective to relax the analog filtering requirements seen in the traditional architecture. The analog filter is cumbersome in an \gls{IC} design and relaxing its requirements is an advantage in terms of die area, performance and robustness of the receiver. The objective is met by a selection of sampling pattern matched to the prior knowledge of the frequency placement of the desired and interfering signals. A simple numerical example demonstrates the principle. The work is part of an ongoing research effort and the different project phases are explained.
ProofPeer: Collaborative Theorem Proving
Venue: arXiv cs.LO 2014
Year: 2014

We define the concept of collaborative theorem proving and outline our plan to make it a reality. We believe that a successful implementation of collaborative theorem proving is a necessary prerequisite for the formal verification of large systems.
Assessing the Zone of Comfort in Stereoscopic Displays using EEG
Venue: arXiv cs.HC 2014
Year: 2014

The conflict between vergence (eye movement) and accommodation (crystalline lens deformation) occurs in every stereoscopic display. It could cause important stress outside the "zone of comfort", when stereoscopic effect is too strong. This conflict has already been studied using questionnaires, during viewing sessions of several minutes. The present pilot study describes an experimental protocol which compares two different comfort conditions using electroencephalography (EEG) over short viewing sequences. Analyses showed significant differences both in event-related potentials (ERP) and in frequency bands power. An uncomfortable stereoscopy correlates with a weaker negative component and a delayed positive component in ERP. It also induces a power decrease in the alpha band and increases in theta and beta bands. With fast responses to stimuli, EEG is likely to enable the conception of adaptive systems, which could tune the stereoscopic experience according to each viewer.
Ensemble estimation of multivariate f-divergence
Venue: arXiv cs.IT 2014
Year: 2014

f-divergence estimation is an important problem in the fields of information theory, machine learning, and statistics. While several divergence estimators exist, relatively few of their convergence rates are known. We derive the MSE convergence rate for a density plug-in estimator of f-divergence. Then by applying the theory of optimally weighted ensemble estimation, we derive a divergence estimator with a convergence rate of O(1/T) that is simple to implement and performs well in high dimensions. We validate our theoretical results with experiments.
Demystifying the Scaling Laws of Dense Wireless Networks: No Linear Scaling in Practice
Venue: arXiv cs.IT 2014
Year: 2014

We optimize the hierarchical cooperation protocol of Ozgur, Leveque and Tse, which is supposed to yield almost linear scaling of the capacity of a dense wireless network with the number of users $n$. Exploiting recent results on the optimality of "treating interference as noise" in Gaussian interference channels, we are able to optimize the achievable average per-link rate and not just its scaling law. Our optimized hierarchical cooperation protocol significantly outperforms the originally proposed scheme. On the negative side, we show that even for very large $n$, the rate scaling is far from linear, and the optimal number of stages $t$ is less than 4, instead of $t \rightarrow \infty$ as required for almost linear scaling. Combining our results and the fact that, beyond a certain user density, the network capacity is fundamentally limited by Maxwell laws, as shown by Francheschetti, Migliore and Minero, we argue that there is indeed no intermediate regime of linear scaling for dense networks in practice.
Improving weather radar by fusion and classification
Venue: arXiv cs.CV 2014
Year: 2014

In air traffic management (ATM) all necessary operations (tactical planing, sector configuration, required staffing, runway configuration, routing of approaching aircrafts) rely on accurate measurements and predictions of the current weather situation. An essential basis of information is delivered by weather radar images (WXR), which, unfortunately, exhibit a vast amount of disturbances. Thus, the improvement of these datasets is the key factor for more accurate predictions of weather phenomena and weather conditions. Image processing methods based on texture analysis and geometric operators allow to identify regions including artefacts as well as zones of missing information. Correction of these zones is implemented by exploiting multi-spectral satellite data (Meteosat Second Generation). Results prove that the proposed system for artefact detection and data correction significantly improves the quality of WXR data and, thus, enables more reliable weather now- and forecast leading to increased ATM safety.