OpenRaiser/Intern-Atlas huggingface dataset:
Predictive Modelling of Bone Age through Classification and Regression of Bone Shapes
Venue: arXiv cs.LG 2014
Year: 2014

Bone age assessment is a task performed daily in hospitals worldwide. This involves a clinician estimating the age of a patient from a radiograph of the non-dominant hand. Our approach to automated bone age assessment is to modularise the algorithm into the following three stages: segment and verify hand outline; segment and verify bones; use the bone outlines to construct models of age. In this paper we address the final question: given outlines of bones, can we learn how to predict the bone age of the patient? We examine two alternative approaches. Firstly, we attempt to train classifiers on individual bones to predict the bone stage categories commonly used in bone ageing. Secondly, we construct regression models to directly predict patient age. We demonstrate that models built on summary features of the bone outline perform better than those built using the one dimensional representation of the outline, and also do at least as well as other automated systems. We show that models constructed on just three bones are as accurate at predicting age as expert human assessors using the standard technique. We also demonstrate the utility of the model by quantifying the importance of ethnicity and sex on age development. Our conclusion is that the feature based system of separating the image processing from the age modelling is the best approach for automated bone ageing, since it offers flexibility and transparency and produces accurate estimates.
A General Framework for Well-Structured Graph Transformation Systems
Venue: arXiv cs.LO 2014
Year: 2014

Graph transformation systems (GTSs) can be seen as wellstructured transition systems (WSTSs), thus obtaining decidability results for certain classes of GTSs. In earlier work it was shown that wellstructuredness can be obtained using the minor ordering as a well-quasiorder. In this paper we extend this idea to obtain a general framework in which several types of GTSs can be seen as (restricted) WSTSs. We instantiate this framework with the subgraph ordering and the induced subgraph ordering and apply it to analyse a simple access rights management system.
Notions of Computation as Monoids
Venue: arXiv cs.LO 2014
Year: 2014

There are different notions of computation, the most popular being monads, applicative functors, and arrows. In this article we show that these three notions can be seen as monoids in a monoidal category. We demonstrate that at this level of abstraction one can obtain useful results which can be instantiated to the different notions of computation. In particular, we show how free constructions and Cayley representations for monoids translate into useful constructions for monads, applicative functors, and arrows. Moreover, the uniform presentation of all three notions helps in the analysis of the relation between them.
Outer bounds for exact repair codes
Venue: arXiv cs.IT 2014
Year: 2014

We address the open problem of establishing the rate region for exact-repair regenerating codes for given parameters (n,k,d). Tian determined the rate region for a (4,3,3) code and found that it lies strictly within the functional-repair rate region. Using different methods, Sasidharan, Senthoor and Kumar proved a non-vanishing gap between the functional-repair outer bound and the exact-repair outer bound for codes with k>=3. Our main results are two improved outer bounds for exact-repair regenerating codes. They capture and then extend essential parts in the proofs by Tian and by Sasidharan, Senthoor and Kumar. We show that the bounds can be combined for further improvements.
Max-Weight Scheduling and Quality-Aware Streaming for Device-to-Device Video Delivery
Venue: arXiv cs.NI 2014
Year: 2014

We propose and analyze centralized and distributed algorithms for device-to-device video scheduling and streaming. The proposed algorithms address jointly the problems of device-to-device link scheduling and video quality adaptation in streaming. Our simulations show that the proposed algorithms significantly outperform conventional separated approaches that treat these two problems independently.
Achieving 100,000,000 database inserts per second using Accumulo and D4M
Venue: arXiv cs.DB 2014
Year: 2014

The Apache Accumulo database is an open source relaxed consistency database that is widely used for government applications. Accumulo is designed to deliver high performance on unstructured data such as graphs of network data. This paper tests the performance of Accumulo using data from the Graph500 benchmark. The Dynamic Distributed Dimensional Data Model (D4M) software is used to implement the benchmark on a 216-node cluster running the MIT SuperCloud software stack. A peak performance of over 100,000,000 database inserts per second was achieved which is 100x larger than the highest previously published value for any other database. The performance scales linearly with the number of ingest clients, number of database servers, and data size. The performance was achieved by adapting several supercomputing techniques to this application: distributed arrays, domain decomposition, adaptive load balancing, and single-program-multiple-data programming.
Diversity Multiplexing Tradeoff of the Half-duplex Slow Fading Multiple Access Channel based on Generalized Quantize-and-Forward Scheme
Venue: arXiv cs.IT 2014
Year: 2014

This paper investigates the Diversity Multiplexing Tradeoff (DMT) of the generalized quantize-and-forward (GQF) relaying scheme over the slow fading half-duplex multiple-access relay channel (HD-MARC). The compress-and-forward (CF) scheme has been shown to achieve the optimal DMT when the channel state information (CSI) of the relay-destination link is available at the relay. However, having the CSI of relay-destination link at relay is not always possible due to the practical considerations of the wireless system. In contrast, in this work, the DMT of the GQF scheme is derived without relay-destination link CSI at the relay. It is shown that even without knowledge of relay-destination CSI, the GQF scheme achieves the same DMT, achievable by CF scheme with full knowledge of CSI.
Study of Security Issues in Pervasive Environment of Next Generation Internet of Things
Venue: arXiv cs.NI 2014
Year: 2014

Internet of Things is a novel concept that semantically implies a world-wide network of uniquely addressable interconnected smart objects. It is aimed at establishing any paradigm in computing. This environment is one where the boundary between virtual and physical world is eliminated. As the network gets loaded with hitherto unknown applications, security threats also become rampant. Current security solutions fail as new threats appear to de-struct the reliability of information. The network has to be transformed to IPv6 enabled network to address huge number of smart objects. Thus new addressing schemes come up with new attacks. Real time analysis of information from the heterogeneous smart objects needs use of cloud services. This can fall prey to cloud specific security threats. Therefore need arises for a review of security threats for a new area having huge demand. Here a study of security issues in this domain is briefly presented.
Racing Multi-Objective Selection Probabilities
Venue: arXiv cs.AI 2014
Year: 2014

In the context of Noisy Multi-Objective Optimization, dealing with uncertainties requires the decision maker to define some preferences about how to handle them, through some statistics (e.g., mean, median) to be used to evaluate the qualities of the solutions, and define the corresponding Pareto set. Approximating these statistics requires repeated samplings of the population, drastically increasing the overall computational cost. To tackle this issue, this paper proposes to directly estimate the probability of each individual to be selected, using some Hoeffding races to dynamically assign the estimation budget during the selection step. The proposed racing approach is validated against static budget approaches with NSGA-II on noisy versions of the ZDT benchmark functions.
Integration of Cloud Computing and Web2.0 Collaboration Technologies in E-Learning
Venue: arXiv cs.CY 2014
Year: 2014

Cloud computing technology is an emerging new computing paradigm for delivering computing services. Although it still in its early stage, it has changed the way how many applications are developed and accessed. This computing approach relies on a number of existing technologies, such as Web2.0, virtualization, Service oriented architecture SOA, Web services,etc.Cloud computing is growing rapidly and becoming an adoptable technology for the organizations especially education institutes, with its dynamic scalability and usage of virtualized resources as a service through the Internet.Today, eLearning is also becoming a very popular and powerful trend.However,in traditional web based eLearning systems,building and maintenance are located onsite in institutions or enterprises, which cause lot of problems to appear such as lacking the support of underlying infrastructure, which can dynamically allocate the needed calculation and storage resources for eLearning systems.As the need for e learning is increasing continuously and its necessary for eLearning systems to keep pace with the right technology needed for development and improvement.However, todays technologies such as Web 2.0, Cloud, etc.enable to build more successful and effective educational environment,that provide collaboration and interaction in eLearning environments.The challenge is to use and integrate these technologies in order to construct tools that allow the best possible learning results.Cloud computing and Web 2.0 are two areas that are starting to strongly effect how the development,deployment and usage of eLearning application.This paper presents the benefits of using cloud computing with the integration of Web 2.0 collaboration technologies in eLearning environment.
Tollan-Xicocotitlan: A reconstructed City by augmented reality
Venue: arXiv cs.CE 2014
Year: 2014

This project presents the analysis, design, implementation and results of Reconstruction Xicocotitlan Tollan-through augmented reality, which will release information about the Toltec culture supplemented by presenting an overview of the main premises of the Xicocotitlan Tollan city supported dimensional models based on the augmented reality technique showing the user a virtual representation of buildings in Tollan.
Location Aided Energy Balancing Strategy in Green Cellular Networks
Venue: arXiv cs.NI 2014
Year: 2014

Most cellular network communication strategies are focused on data traffic scenarios rather than energy balance and efficient utilization. Thus mobile users in hot cells may suffer from low throughput due to energy loading imbalance problem. In state of art cellular network technologies, relay stations extend cell coverage and enhance signal strength for mobile users. However, busy traffic makes the relay stations in hot area run out of energy quickly. In this paper, we propose an energy balancing strategy in which the mobile nodes are able to dynamically select and hand over to the relay station with the highest potential energy capacity to resume communication. Key to the strategy is that each relay station merely maintains two parameters that contains the trend of its previous energy consumption and then predicts its future quantity of energy, which is defined as the relay station potential energy capacity. Then each mobile node can select the relay station with the highest potential energy capacity. Simulations demonstrate that our approach significantly increase the aggregate throughput and the average life time of relay stations in cellular network environment.
STAIR Codes: A General Family of Erasure Codes for Tolerating Device and Sector Failures
Venue: arXiv cs.IT 2014
Year: 2014

Practical storage systems often adopt erasure codes to tolerate device failures and sector failures, both of which are prevalent in the field. However, traditional erasure codes employ device-level redundancy to protect against sector failures, and hence incur significant space overhead. Recent sector-disk (SD) codes are available only for limited configurations. By making a relaxed but practical assumption, we construct a general family of erasure codes called \emph{STAIR codes}, which efficiently and provably tolerate both device and sector failures without any restriction on the size of a storage array and the numbers of tolerable device failures and sector failures. We propose the \emph{upstairs encoding} and \emph{downstairs encoding} methods, which provide complementary performance advantages for different configurations. We conduct extensive experiments on STAIR codes in terms of space saving, encoding/decoding speed, and update cost. We demonstrate that STAIR codes not only improve space efficiency over traditional erasure codes, but also provide better computational efficiency than SD codes based on our special code construction. Finally, we present analytical models that characterize the reliability of STAIR codes, and show that the support of a wider range of configurations by STAIR codes is critical for tolerating sector failure bursts discovered in the field.
A Symbol-Based Estimation Technique for Inter-vehicular Communication Performance Optimization
Venue: arXiv cs.NI 2014
Year: 2014

The aim of this paper is to enhance the quality of Orthogonal Frequency Division Multiplexing OFDM estimation in dedicated vehicular communication transmission V2X networks. Wireless Access in Vehicular Environment WAVE as also known IEEE 802.11p represents the standard for these networks. Developing a reliable inter-vehicular V2X communication has to focus on optimizing its real performances. In this work, we studied the fact that WAVE transmission uses the channel characteristics designed for indoor and stationary communication terminals in IEEE 802.11a. In this paper, we propose an approach to overcome this mobility problem of terminal communication. The considered solution consists in using pilot estimation technique to reduce the high bit error rate. First, we highlight the impact of rearranging the pilot symbol positions on the quality of transmission QoT. Second, we try to overcome one of the PHY layer estimation constraints by adding two new pilot symbols. By considering pilot symbol aided channel estimation at the transmitter, we focus on Least Square LS and Minimum Mean Square Error MMSE channel estimation on the receiver. A range of simulations is carried out according to ratio between the Bit Error Rate BER and the Signal to Noise Ratio SNR. We demonstrate that rearranging pilot pattern can offer better results than standardized ones. Furthermore, we prove that adding pilots symbols can provide the best performances.
Transpose-free Fast Fourier Transform for Turbulence Simulation
Venue: arXiv cs.MS 2014
Year: 2014

Pseudo-spectral method is one of the most accurate techniques for simulating turbulent flows. Fast Fourier transform (FFT) is an integral part of this method. In this paper, we present a new procedure to compute FFT in which we save operations during interprocess communications by avoiding transpose of the array. As a result, our transpose-free FFT is 15\% to 20\% faster than FFTW.
Gain-scheduled synchronization of parameter varying systems via relative $H_\infty$ consensus with application to synchronization of uncertain bilinear systems
Venue: arXiv cs.SY 2014
Year: 2014

The paper considers a problem of consensus-based synchronization of uncertain parameter varying multi-agent systems. We present a method for constructing consensus-based synchronization protocol schedules for each agent to ensure it synchronizes with a reference parameter-varying system. The proposed protocol guarantees a specified level of $H_\infty$ transient consensus between the agents. The algorithm uses a consensus-preserving interpolation and produces continuous (in the scheduling parameter) coefficients for the protocol. An application to synchronization of uncertain bilinear systems is discussed.
Constant Factor Approximation for Balanced Cut in the PIE model
Venue: arXiv cs.DS 2014
Year: 2014

We propose and study a new semi-random semi-adversarial model for Balanced Cut, a planted model with permutation-invariant random edges (PIE). Our model is much more general than planted models considered previously. Consider a set of vertices V partitioned into two clusters $L$ and $R$ of equal size. Let $G$ be an arbitrary graph on $V$ with no edges between $L$ and $R$. Let $E_{random}$ be a set of edges sampled from an arbitrary permutation-invariant distribution (a distribution that is invariant under permutation of vertices in $L$ and in $R$). Then we say that $G + E_{random}$ is a graph with permutation-invariant random edges. We present an approximation algorithm for the Balanced Cut problem that finds a balanced cut of cost $O(|E_{random}|) + n \text{polylog}(n)$ in this model. In the regime when $|E_{random}| = Ω(n \text{polylog}(n))$, this is a constant factor approximation with respect to the cost of the planted cut.
A CNL for Contract-Oriented Diagrams
Venue: arXiv cs.CL 2014
Year: 2014

We present a first step towards a framework for defining and manipulating normative documents or contracts described as Contract-Oriented (C-O) Diagrams. These diagrams provide a visual representation for such texts, giving the possibility to express a signatory's obligations, permissions and prohibitions, with or without timing constraints, as well as the penalties resulting from the non-fulfilment of a contract. This work presents a CNL for verbalising C-O Diagrams, a web-based tool allowing editing in this CNL, and another for visualising and manipulating the diagrams interactively. We then show how these proof-of-concept tools can be used by applying them to a small example.
Runtime Enforcement for Component-Based Systems
Venue: arXiv cs.SE 2014
Year: 2014

Runtime enforcement is an increasingly popular and effective dynamic validation technique aiming to ensure the correct runtime behavior (w.r.t. a formal specification) of systems using a so-called enforcement monitor. In this paper we introduce runtime enforcement of specifications on component-based systems (CBS) modeled in the BIP (Behavior, Interaction and Priority) framework. BIP is a powerful and expressive component-based framework for formal construction of heterogeneous systems. However, because of BIP expressiveness, it remains difficult to enforce at design-time complex behavioral properties. First we propose a theoretical runtime enforcement framework for CBS where we delineate a hierarchy of sets of enforceable properties (i.e., properties that can be enforced) according to the number of observational steps a system is allowed to deviate from the property (i.e., the notion of k-step enforceability). To ensure the observational equivalence between the correct executions of the initial system and the monitored system, we show that i) only stutter-invariant properties should be enforced on CBS with our monitors, ii) safety properties are 1-step enforceable. Given an abstract enforcement monitor (as a finite-state machine) for some 1-step enforceable specification, we formally instrument (at relevant locations) a given BIP system to integrate the monitor. At runtime, the monitor observes and automatically avoids any error in the behavior of the system w.r.t. the specification. Our approach is fully implemented in an available tool that we used to i) avoid deadlock occurrences on a dining philosophers benchmark, and ii) ensure the correct placement of robots on a map.
CNN: Single-label to Multi-label
Venue: arXiv cs.CV 2014
Year: 2014

Convolutional Neural Network (CNN) has demonstrated promising performance in single-label image classification tasks. However, how CNN best copes with multi-label images still remains an open problem, mainly due to the complex underlying object layouts and insufficient multi-label training images. In this work, we propose a flexible deep CNN infrastructure, called Hypotheses-CNN-Pooling (HCP), where an arbitrary number of object segment hypotheses are taken as the inputs, then a shared CNN is connected with each hypothesis, and finally the CNN output results from different hypotheses are aggregated with max pooling to produce the ultimate multi-label predictions. Some unique characteristics of this flexible deep CNN infrastructure include: 1) no ground truth bounding box information is required for training; 2) the whole HCP infrastructure is robust to possibly noisy and/or redundant hypotheses; 3) no explicit hypothesis label is required; 4) the shared CNN may be well pre-trained with a large-scale single-label image dataset, e.g. ImageNet; and 5) it may naturally output multi-label prediction results. Experimental results on Pascal VOC2007 and VOC2012 multi-label image datasets well demonstrate the superiority of the proposed HCP infrastructure over other state-of-the-arts. In particular, the mAP reaches 84.2% by HCP only and 90.3% after the fusion with our complementary result in [47] based on hand-crafted features on the VOC2012 dataset, which significantly outperforms the state-of-the-arts with a large margin of more than 7%.
Weak Secrecy in the Multi-Way Untrusted Relay Channel with Compute-and-Forward
Venue: arXiv cs.IT 2014
Year: 2014

We investigate the problem of secure communications in a Gaussian multi-way relay channel applying the compute-and-forward scheme using nested lattice codes. All nodes employ half-duplex operation and can exchange confidential messages only via an untrusted relay. The relay is assumed to be honest but curious, i.e., an eavesdropper that conforms to the system rules and applies the intended relaying scheme. We start with the general case of the single-input multiple-output (SIMO) L-user multi-way relay channel and provide an achievable secrecy rate region under a weak secrecy criterion. We show that the securely achievable sum rate is equivalent to the difference between the computation rate and the multiple access channel (MAC) capacity. Particularly, we show that all nodes must encode their messages such that the common computation rate tuple falls outside the MAC capacity region of the relay. We provide results for the single-input single-output (SISO) and the multiple-input single-input (MISO) L-user multi-way relay channel as well as the two-way relay channel. We discuss these results and show the dependency between channel realization and achievable secrecy rate. We further compare our result to available results in the literature for different schemes and show that the proposed scheme operates close to the compute-and-forward rate without secrecy.
Universal Lyndon Words
Venue: arXiv cs.DM 2014
Year: 2014

A word $w$ over an alphabet $Σ$ is a Lyndon word if there exists an order defined on $Σ$ for which $w$ is lexicographically smaller than all of its conjugates (other than itself). We introduce and study \emph{universal Lyndon words}, which are words over an $n$-letter alphabet that have length $n!$ and such that all the conjugates are Lyndon words. We show that universal Lyndon words exist for every $n$ and exhibit combinatorial and structural properties of these words. We then define particular prefix codes, which we call Hamiltonian lex-codes, and show that every Hamiltonian lex-code is in bijection with the set of the shortest unrepeated prefixes of the conjugates of a universal Lyndon word. This allows us to give an algorithm for constructing all the universal Lyndon words.