OpenRaiser/Intern-Atlas huggingface dataset:
Convolutional Simplex Projection Network (CSPN) for Weakly Supervised Semantic Segmentation
Venue: arXiv cs.CV 2018
Year: 2018

Weakly supervised semantic segmentation has been a subject of increased interest due to the scarcity of fully annotated images. We introduce a new approach for solving weakly supervised semantic segmentation with deep Convolutional Neural Networks (CNNs). The method introduces a novel layer which applies simplex projection on the output of a neural network using area constraints of class objects. The proposed method is general and can be seamlessly integrated into any CNN architecture. Moreover, the projection layer allows strongly supervised models to be adapted to weakly supervised models effortlessly by substituting ground truth labels. Our experiments have shown that applying such an operation on the output of a CNN improves the accuracy of semantic segmentation in a weakly supervised setting with image-level labels.
Deep Learning on Retina Images as Screening Tool for Diagnostic Decision Support
Venue: arXiv cs.CV 2018
Year: 2018

In this project, we developed a deep learning system applied to human retina images for medical diagnostic decision support. The retina images were provided by EyePACS. These images were used in the framework of a Kaggle contest, whose purpose to identify diabetic retinopathy signs through an automatic detection system. Using as inspiration one of the solutions proposed in the contest, we implemented a model that successfully detects diabetic retinopathy from retina images. After a carefully designed preprocessing, the images were used as input to a deep convolutional neural network (CNN). The CNN performed a feature extraction process followed by a classification stage, which allowed the system to differentiate between healthy and ill patients using five categories. Our model was able to identify diabetic retinopathy in the patients with an agreement rate of 76.73% with respect to the medical expert's labels for the test data.
Using Multi-Core HW/SW Co-design Architecture for Accelerating K-means Clustering Algorithm
Venue: arXiv cs.DC 2018
Year: 2018

The capability of classifying and clustering a desired set of data is an essential part of building knowledge from data. However, as the size and dimensionality of input data increases, the run-time for such clustering algorithms is expected to grow superlinearly, making it a big challenge when dealing with BigData. K-mean clustering is an essential tool for many big data applications including data mining, predictive analysis, forecasting studies, and machine learning. However, due to large size (volume) of Big-Data, and large dimensionality of its data points, even the application of a simple k-mean clustering may become extremely time and resource demanding. Specially when it is necessary to have a fast and modular dataset analysis flow. In this paper, we demonstrate that using a two-level filtering algorithm based on binary kd-tree structure is able to decrease the time of convergence in K-means algorithm for large datasets. The two-level filtering algorithm based on binary kd-tree structure evolves the SW to naturally divide the classification into smaller data sets, based on the number of available cores and size of logic available in a target FPGA. The empirical result on this two-level structure over multi-core FPGA-based architecture provides 330X speed-up compared to a conventional software-only solution.
Time-efficient Garbage Collection in SSDs
Venue: arXiv cs.PF 2018
Year: 2018

SSDs are currently replacing magnetic disks in many application areas. A challenge of the underlying flash technology is that data cannot be updated in-place. A block consisting of many pages must be completely erased before a single page can be rewritten. This victim block can still contain valid pages which need to be copied to other blocks before erasure. The objective of garbage collection strategies is to minimize write amplification induced by copying valid pages from victim blocks while minimizing the performance overhead of the victim selection. Victim selection strategies minimizing write amplification, like the cost-benefit approach, have linear runtime, while the write amplifications of time-efficient strategies, like the greedy strategy, significantly reduce the lifetime of SSDs. In this paper, we propose two strategies which optimize the performance of cost-benefit, while (almost) preserving its write amplification. Trace-driven simulations for single- and multi-channel SSDs show that the optimizations help to keep the write amplification low while improving the runtime by up to 24-times compared to the original cost-benefit strategy, so that the new strategies can be used in multi-TByte SSDs.
A Synchronized Stereo and Plenoptic Visual Odometry Dataset
Venue: arXiv cs.CV 2018
Year: 2018

We present a new dataset to evaluate monocular, stereo, and plenoptic camera based visual odometry algorithms. The dataset comprises a set of synchronized image sequences recorded by a micro lens array (MLA) based plenoptic camera and a stereo camera system. For this, the stereo cameras and the plenoptic camera were assembled on a common hand-held platform. All sequences are recorded in a very large loop, where beginning and end show the same scene. Therefore, the tracking accuracy of a visual odometry algorithm can be measured from the drift between beginning and end of the sequence. For both, the plenoptic camera and the stereo system, we supply full intrinsic camera models, as well as vignetting data. The dataset consists of 11 sequences which were recorded in challenging indoor and outdoor scenarios. We present, by way of example, the results achieved by state-of-the-art algorithms.
Deterministic Hypothesis Generation for Robust Fitting of Multiple Structures
Venue: arXiv cs.CV 2018
Year: 2018

We present a novel algorithm for generating robust and consistent hypotheses for multiple-structure model fitting. Most of the existing methods utilize random sampling which produce varying results especially when outlier ratio is high. For a structure where a model is fitted, the inliers of other structures are regarded as outliers when multiple structures are present. Global optimization has recently been investigated to provide stable and unique solutions, but the computational cost of the algorithms is prohibitively high for most image data with reasonable sizes. The algorithm presented in this paper uses a maximum feasible subsystem (MaxFS) algorithm to generate consistent initial hypotheses only from partial datasets in spatially overlapping local image regions. Our assumption is that each genuine structure will exist as a dominant structure in at least one of the local regions. To refine initial hypotheses estimated from partial datasets and to remove residual tolerance dependency of the MaxFS algorithm, iterative re-weighted L1 (IRL1) minimization is performed for all the image data. Initial weights of IRL1 framework are determined from the initial hypotheses generated in local regions. Our approach is significantly more efficient than those that use only global optimization for all the image data. Experimental results demonstrate that the presented method can generate more reliable and consistent hypotheses than random-sampling methods for estimating single and multiple structures from data with a large amount of outliers. We clearly expose the influence of algorithm parameter settings on the results in our experiments.
Rendering Elimination: Early Discard of Redundant Tiles in the Graphics Pipeline
Venue: arXiv cs.AR 2018
Year: 2018

GPUs are one of the most energy-consuming components for real-time rendering applications, since a large number of fragment shading computations and memory accesses are involved. Main memory bandwidth is especially taxing battery-operated devices such as smartphones. Tile-Based Rendering GPUs divide the screen space into multiple tiles that are independently rendered in on-chip buffers, thus reducing memory bandwidth and energy consumption. We have observed that, in many animated graphics workloads, a large number of screen tiles have the same color across adjacent frames. In this paper, we propose Rendering Elimination (RE), a novel micro-architectural technique that accurately determines if a tile will be identical to the same tile in the preceding frame before rasterization by means of comparing signatures. Since RE identifies redundant tiles early in the graphics pipeline, it completely avoids the computation and memory accesses of the most power consuming stages of the pipeline, which substantially reduces the execution time and the energy consumption of the GPU. For widely used Android applications, we show that RE achieves an average speedup of 1.74x and energy reduction of 43% for the GPU/Memory system, surpassing by far the benefits of Transaction Elimination, a state-of-the-art memory bandwidth reduction technique available in some commercial Tile-Based Rendering GPUs.
A User Modeling Pipeline for Studying Polarized Political Events in Social Media
Venue: arXiv cs.SI 2018
Year: 2018

This paper presents a user modeling pipeline to analyze discussions and opinions shared on social media regarding polarized political events (e.g., public polls). The pipeline follows a four-step methodology. First, social media posts and users metadata are crawled. Second, a filtering mechanism is applied to filter spammers and bot users. As a third step, demographics information is extracted out of the valid users, namely gender, age, ethnicity and location information. Finally, the political polarity of the users with respect to the analyzed event is predicted. In the scope of this work, our proposed pipeline is applied to two referendum scenarios (independence of Catalonia in Spain and autonomy of Lombardy in Italy) in order to assess the performance of the approach with respect to the capability of collecting correct insights on the demographics of social media users and of predicting the poll results based on the opinions shared by the users. Experiments show that the method was effective in predicting the political trends for the Catalonia case, but not for the Lombardy case. Among the various motivations for this, we noticed that in general Twitter was more representative of the users opposing the referendum than the ones in favor.
Investigating the Intersection of Science Fiction, Human-Computer Interaction and Computer Science Research
Venue: arXiv cs.HC 2018
Year: 2018

This paper outlines ongoing dissertation research located in the intersection of science fiction, human-computer interaction and computer science. Through an interdisciplinary perspective, drawing from fields such as human-computer interaction, film theory and studies of science and technology, qualitative and quantitative content analysis techniques are used to contextually analyze expressions of science fiction in peer-reviewed computer science research repositories, such as the ACM or IEEE Xplore Digital Libraries. This paper concisely summarizes and introduces the relationship of science fiction and computer science research and presents the research questions, aims and implications in addition to prior work and study methodology. In the latter part of this work-in-progress report, preliminary results, current limitations, future work and a post-dissertation trajectory are outlined.
Big Data: the End of the Scientific Method?
Venue: arXiv cs.GL 2018
Year: 2018

We argue that the boldest claims of Big Data are in need of revision and toning-down, in view of a few basic lessons learned from the science of complex systems. We point out that, once the most extravagant claims of Big Data are properly discarded, a synergistic merging of BD with big theory offers considerable potential to spawn a new scientific paradigm capable of overcoming some of the major barriers confronted by the modern scientific method originating with Galileo. These obstacles are due to the presence of nonlinearity, nonlocality and hyperdimensions which one encounters frequently in multiscale modelling.
Decentralized Cooperative Planning for Automated Vehicles with Hierarchical Monte Carlo Tree Search
Venue: arXiv cs.AI 2018
Year: 2018

Today's automated vehicles lack the ability to cooperate implicitly with others. This work presents a Monte Carlo Tree Search (MCTS) based approach for decentralized cooperative planning using macro-actions for automated vehicles in heterogeneous environments. Based on cooperative modeling of other agents and Decoupled-UCT (a variant of MCTS), the algorithm evaluates the state-action-values of each agent in a cooperative and decentralized manner, explicitly modeling the interdependence of actions between traffic participants. Macro-actions allow for temporal extension over multiple time steps and increase the effective search depth requiring fewer iterations to plan over longer horizons. Without predefined policies for macro-actions, the algorithm simultaneously learns policies over and within macro-actions. The proposed method is evaluated under several conflict scenarios, showing that the algorithm can achieve effective cooperative planning with learned macro-actions in heterogeneous environments.
Recurrent Neural Network-based Model Predictive Control for Continuous Pharmaceutical Manufacturing
Venue: arXiv cs.SY 2018
Year: 2018

The pharmaceutical industry has witnessed exponential growth in transforming operations towards continuous manufacturing to effectively achieve increased profitability, reduced waste, and extended product range. Model Predictive Control (MPC) can be applied for enabling this vision, in providing superior regulation of critical quality attributes. For MPC, obtaining a workable model is of fundamental importance, especially in the presence of complex reaction kinetics and process dynamics. Whilst physics-based models are desirable, it is not always practical to obtain one effective and fit-for-purpose model. Instead, within industry, data-driven system-identification approaches have been found to be useful and widely deployed in MPC solutions. In this work, we demonstrated the applicability of Recurrent Neural Networks (RNNs) for MPC applications in continuous pharmaceutical manufacturing. We have shown that RNNs are especially well-suited for modeling dynamical systems due to their mathematical structure and satisfactory closed-loop control performance can be yielded for MPC in continuous pharmaceutical manufacturing.
Video-based computer aided arthroscopy for patient specific reconstruction of the Anterior Cruciate Ligament
Venue: arXiv cs.CV 2018
Year: 2018

The Anterior Cruciate Ligament (ACL) tear is a common medical condition that is treated using arthroscopy by pulling a tissue graft through a tunnel opened with a drill. The correct anatomical position and orientation of this tunnel is crucial for knee stability, and drilling an adequate bone tunnel is the most technically challenging part of the procedure. This paper presents, for the first time, a guidance system based solely on intra-operative video for guiding the drilling of the tunnel. Our solution uses small, easily recognizable visual markers that are attached to the bone and tools for estimating their relative pose. A recent registration algorithm is employed for aligning a pre-operative image of the patient's anatomy with a set of contours reconstructed by touching the bone surface with an instrumented tool. Experimental validation using ex-vivo data shows that the method enables the accurate registration of the pre-operative model with the bone, providing useful information for guiding the surgeon during the medical procedure.
A Surprising Linear Relationship Predicts Test Performance in Deep Networks
Venue: arXiv cs.LG 2018
Year: 2018

Given two networks with the same training loss on a dataset, when would they have drastically different test losses and errors? Better understanding of this question of generalization may improve practical applications of deep networks. In this paper we show that with cross-entropy loss it is surprisingly simple to induce significantly different generalization performances for two networks that have the same architecture, the same meta parameters and the same training error: one can either pretrain the networks with different levels of "corrupted" data or simply initialize the networks with weights of different Gaussian standard deviations. A corollary of recent theoretical results on overfitting shows that these effects are due to an intrinsic problem of measuring test performance with a cross-entropy/exponential-type loss, which can be decomposed into two components both minimized by SGD -- one of which is not related to expected classification performance. However, if we factor out this component of the loss, a linear relationship emerges between training and test losses. Under this transformation, classical generalization bounds are surprisingly tight: the empirical/training loss is very close to the expected/test loss. Furthermore, the empirical relation between classification error and normalized cross-entropy loss seem to be approximately monotonic
Game-Theoretic Optimization for Machine-Type Communications Under QoS Guarantee
Venue: arXiv cs.IT 2018
Year: 2018

Massive machine-type communication (mMTC) is a new focus of services in fifth generation (5G) communication networks. The associated stringent delay requirement of end-to-end (E2E) service deliveries poses technical challenges. In this paper, we propose a joint random access and data transmission protocol for mMTC to guarantee E2E service quality of different traffic types. First, we develop a priority-queueing-based access class barring (ACB) model and a novel effective capacity is derived. Then, we model the priority-queueing-based ACB policy as a non-cooperative game, where utility is defined as the difference between effective capacity and access penalty price. We prove the existence and uniqueness of Nash equilibrium (NE) of the non-cooperative game, which is also a sub-modular utility maximization problem and can be solved by a greedy updating algorithm with convergence to the unique NE. To further improve the efficiency, we present a price-update algorithm, which converges to a local optimum. Simulations demonstrate the performance of the derived effective capacity and the effectiveness of the proposed algorithms.
RuntimeSearch: Ctrl+F for a Running Program
Venue: arXiv cs.SE 2018
Year: 2018

Developers often try to find occurrences of a certain term in a software system. Traditionally, a text search is limited to static source code files. In this paper, we introduce a simple approach, RuntimeSearch, where the given term is searched in the values of all string expressions in a running program. When a match is found, the program is paused and its runtime properties can be explored with a traditional debugger. The feasibility and usefulness of RuntimeSearch is demonstrated on a medium-sized Java project.
Turbulucid: A Python Package for Post-Processing of Fluid Flow Simulations
Venue: arXiv cs.CE 2018
Year: 2018

A Python package for post-processing of plane two-dimensional data from computational fluid dynamics simulations is presented. The package, called turbulucid, provides means for scripted, reproducible analysis of large simulation campaigns and includes routines for both data extraction and visualization. For the former, the Visualization Toolkit (VTK) is used, allowing for post-processing of simulations performed on unstructured meshes. For visualization, several matplotlib-based functions for creating highly customizable, publication-quality plots are provided. To demonstrate turbulucid's functionality it is here applied to post-processing a simulation of a flow over a backward-facing step. The implementation and architecture of the package are also discussed, as well as its reuse potential.
Improving the Integrality Gap for Multiway Cut
Venue: arXiv cs.DS 2018
Year: 2018

In the multiway cut problem, we are given an undirected graph with non-negative edge weights and a collection of $k$ terminal nodes, and the goal is to partition the node set of the graph into $k$ non-empty parts each containing exactly one terminal so that the total weight of the edges crossing the partition is minimized. The multiway cut problem for $k\ge 3$ is APX-hard. For arbitrary $k$, the best-known approximation factor is $1.2965$ due to [Sharma and Vondrák, 2014] while the best known inapproximability factor is $1.2$ due to [Angelidakis, Makarychev and Manurangsi, 2017]. In this work, we improve on the lower bound to $1.20016$ by constructing an integrality gap instance for the CKR relaxation. A technical challenge in improving the gap has been the lack of geometric tools to understand higher-dimensional simplices. Our instance is a non-trivial $3$-dimensional instance that overcomes this technical challenge. We analyze the gap of the instance by viewing it as a convex combination of $2$-dimensional instances and a uniform 3-dimensional instance. We believe that this technique could be exploited further to construct instances with larger integrality gap. One of the ingredients of our proof technique is a generalization of a result on \emph{Sperner admissible labelings} due to [Mirzakhani and Vondrák, 2015] that might be of independent combinatorial interest.
Method for Hybrid Precision Convolutional Neural Network Representation
Venue: arXiv cs.NE 2018
Year: 2018

This invention addresses fixed-point representations of convolutional neural networks (CNN) in integrated circuits. When quantizing a CNN for a practical implementation there is a trade-off between the precision used for operations between coefficients and data and the accuracy of the system. A homogenous representation may not be sufficient to achieve the best level of performance at a reasonable cost in implementation complexity or power consumption. Parsimonious ways of representing data and coefficients are needed to improve power efficiency and throughput while maintaining accuracy of a CNN.
Asynchronous Ripple Carry Adder based on Area Optimized Early Output Dual-Bit Full Adder
Venue: arXiv cs.AR 2018
Year: 2018

This technical note presents the design of a new area optimized asynchronous early output dual-bit full adder (DBFA). An asynchronous ripple carry adder (RCA) is constructed based on the new asynchronous DBFAs and existing asynchronous early output single-bit full adders (SBFAs). The asynchronous DBFAs and SBFAs incorporate redundant logic and are encoded using the delay-insensitive dual-rail code (i.e. homogeneous data encoding) and follow a 4-phase return-to-zero handshaking. Compared to the previous asynchronous RCAs involving DBFAs and SBFAs, which are based on homogeneous or heterogeneous delay-insensitive data encodings and which correspond to different timing models, the early output asynchronous RCA incorporating the proposed DBFAs and/or SBFAs is found to result in reduced area for the dual-operand addition operation and feature significantly less latency than the asynchronous RCAs which consist of only SBFAs. The proposed asynchronous DBFA requires 28.6% less silicon than the previously reported asynchronous DBFA. For a 32-bit asynchronous RCA, utilizing 2 stages of SBFAs in the least significant positions and 15 stages of DBFAs in the more significant positions leads to optimization in the latency. The new early output 32-bit asynchronous RCA containing DBFAs and SBFAs reports the following optimizations in design metrics over its counterparts: i) 18.8% reduction in area than a previously reported 32-bit early output asynchronous RCA which also has 15 stages of DBFAs and 2 stages of SBFAs, ii) 29.4% reduction in latency than a 32-bit early output asynchronous RCA containing only SBFAs.