Reviewerly/exHarmony huggingface dataset:
Finding GEMS: Multi-Scale Dictionaries For High-Dimensional Graph Signals

Modern data introduces new challenges to classic signal processing approaches, leading to a growing interest in the field of graph signal processing. A powerful and well-established model for real world signals in various domains is sparse representation over a dictionary, combined with the ability to train the dictionary from signal examples. This model has been successfully applied to graph signals as well by integrating the underlying graph topology into the learned dictionary. Nonetheless, dictionary learning methods for graph signals are typically restricted to small dimensions due to the computational constraints that the dictionary learning problem entails, and due to the direct use of the graph Laplacian matrix. In this paper, we propose a graph-enhanced multi-scale dictionary learning algorithm that applies to a broader class of graph signals, and is capable of handling much higher dimensional data. We incorporate the underlying graph topology both implicitly, by forcing the learned dictionary atoms to be sparse combinations of graph-wavelet functions, and explicitly, by adding direct graph constraints to promote smoothness in both the feature and manifold domains. The resulting atoms are thus adapted to the data of interest, while adhering to the underlying graph structure and possessing a desired multi-scale property. Experimental results on several datasets, representing both synthetic and real network data of different nature, demonstrate the effectiveness of the proposed algorithm for graph signal processing even in high dimensions.
Differential Geometry in Edge Detection: Accurate Estimation of Position, Orientation and Curvature

The vast majority of edge detection literature has aimed at improving edge recall and precision, with relatively few addressing the accuracy of edge orientation estimates which are often based on gradient. We show that first-order estimates of orientation can have significant error and this can be remedied by employing Third-Order estimates. This paper aims at estimating differential geometry attributes of an edge, namely, localization, orientation, and curvature, as well as edge topology, and develop robust numerical techniques in gray-scale and color images, applicable to a variety of popular edge detectors, such as gradient-based, gPb and SE. Second, a combinatorial model of edge grouping in a small neighborhood is developed to capture all geometrically consistent grouping called curvels, which establish: (i) edge topology in the form of potential links between an edge and other edges; (ii) an accurate curvature estimate for each possible grouping, whose performance is comparable to methods which use global and multi-scale methods; (iii) a more accurate localization of an edge. These have been evaluated using four distinct methodologies (i) traditional human annotated datasets; (ii) using coherence measure; (iii) stability analysis under visual perturbation, and (iv) utilitarian evaluation, and show meaningful improvements.
Information Formulation of the UDU Kalman Filter

A new information formulation of the Kalman filter is presented where the information matrix is parameterized as the product of an upper triangular matrix, a diagonal matrix, and the transpose of a triangular matrix (referred as UDU factorization). The UDU factorization of the Kalman filter is known for its numerical stability; this paper extends the technique to the information filter. A distinct characteristic of the new algorithm is that measurements can be processed as vectors, while the classic UDU factorization requires scalar measurement processing, i.e., a diagonal measurement noise covariance matrix.
A Bi-LSTM memory network for end-to-end goal-oriented dialog learning

We develop a model to satisfy the requirements of Dialog System Technology Challenge 6 (DSTC6) Track 1: building an end-to-end dialog systems for goal-oriented applications. This task involves learning a dialog policy from transactional dialogs in a given domain. Automatic system responses are generated using given task-oriented dialog data (http://workshop.colips.org/dstc6/index.html). As this task has a similar structure to a question answering task (Weston et al., 2015), we employ the MemN2N architecture (Sukhbaatar et al., 2015), which outperforms models based on recurrent neural networks or long short-term memory (LSTM). However, two problems arise when applying this model to the DSTC6 task. First, we encounter an out-of-vocabulary problem, which we resolve by categorizing the metadata types of words that exist in the knowledge base; the metadata is similar to the named entity. Second, the original memory network model has a weak ability to reflect sufficient temporal information, because it only uses sentence-level embeddings. Therefore, we add bidirectional LSTM (Bi-LSTM) at the beginning of the model to better reflect temporal information. The experimental results demonstrate that our model reflects temporal features well. Furthermore, our model achieves state-of-the-art performance among the memory networks, and is comparable to hybrid code networks (Ham et al., 2017) and hierarchical LSTM model (Bai et al., 2017) which is not an end-to-end architecture.
Keypoint Transfer for Fast Whole-Body Segmentation

We introduce an approach for image segmentation based on sparse correspondences between keypoints in testing and training images. Keypoints represent automatically identified distinctive image locations, where each keypoint correspondence suggests a transformation between images. We use these correspondences to transfer the label maps of entire organs from the training images to the test image. The keypoint transfer algorithm includes three steps: 1) keypoint matching; 2) voting-based keypoint labeling; and 3) keypoint-based probabilistic transfer of organ segmentations. We report segmentation results for abdominal organs in whole-body CT and MRI, as well as in contrast-enhanced CT and MRI. Our method offers a speed-up of about three orders of magnitude in comparison with common multi-atlas segmentation while achieving an accuracy that compares favorably. Moreover, keypoint transfer does not require the registration to an atlas or a training phase. Finally, the method allows for the segmentation of scans with a highly variable field-of-view.
Aligning concepts across proof assistant libraries

As the knowledge available in the computer understandable proof corpora grows, recognizing repeating patterns becomes a necessary requirement in order to organize, synthesize, share, and transmit ideas. In this work, we automatically discover patterns in the libraries of interactive theorem provers and thus provide the basis for such applications for proof assistants. This involves detecting close properties, inducing the presence of matching concepts, as well as dynamically evaluating the quality of matches from the similarity of the environment of each concept. We further propose a classification process, which involves a disambiguation mechanism to decide which concepts actually represent the same mathematical ideas. We evaluate the approach on the libraries of six proof assistants based on different logical foundations: HOL4, HOL Light, and Isabelle/HOL for higher-order logic, Coq and Matita for intuitionistic type theory, and the Mizar Mathematical Library for set theory. Comparing the structures available in these libraries our algorithm automatically discovers hundreds of isomorphic concepts and thousands of highly similar ones.
Scaling Up In-Memory-Computing Classifiers via Boosted Feature Subsets in Banked Architectures

In-memory computing is an emerging approach for overcoming memory-accessing bottlenecks, by eliminating the costs of explicitly moving data from point of storage to point of computation outside the array. However, computation increases the dynamic range of signals, such that performing it via the existing structure of dense memory substantially squeezes the signalto-noise ratio (SNR). In this brief, we explore how computations can be scaled up, to jointly optimize energy/latency/bandwidth gains with SNR requirements. We employ algorithmic techniques to decompose computations so that they can be mapped to multiple parallel memory banks operating at chosen optimal points. Specifically focusing on in-memory classification, we consider a custom IC in 130-nm CMOS IC and demonstrate an algorithm combining error-adaptive classifier boosting and multi-armed bandits, to enable segmentation of a feature vector into multiple subsets. The measured performance of 10-way MNIST digit classification, using images downsampled to 16×16 pixels (mapped across four separate banks), is 91%, close to that simulated using full unsegmented feature vectors. The energy per classification is 879.7 pJ, 14.3× lower than that of a system based on separated memory and digital accelerator.
Invertible Particle-Flow-Based Sequential MCMC With Extension to Gaussian Mixture Noise Models

Sequential state estimation in non-linear and non-Gaussian state spaces has a wide range of applications in statistics and signal processing. One of the most effective non-linear filtering approaches, particle filtering, suffers from weight degeneracy in high-dimensional filtering scenarios. Several avenues have been pursued to address high-dimensionality. Among these, particle flow particle filters construct effective proposal distributions by using invertible flow to migrate particles continuously from the prior distribution to the posterior, and sequential Markov chain Monte Carlo (SMCMC) methods use a Metropolis-Hastings (MH) accept-reject approach to improve filtering performance. In this paper, we propose to combine the strengths of invertible particle flow and SMCMC by constructing a composite Metropolis-Hastings (MH) kernel within the SMCMC framework using invertible particle flow. In addition, we propose a Gaussian mixture model (GMM)-based particle flow algorithm to construct effective MH kernels for multi-modal distributions. Simulation results show that for high-dimensional state estimation example problems the proposed kernels significantly increase the acceptance rate with minimal additional computational overhead and improve estimation accuracy compared with state-of-the-art filtering algorithms.
Exemplar-based depth inpainting with arbitrary-shape patches and cross-modal matching

Commodity RGB-D cameras can provide texture and depth maps in real-time, and thus have facilitated the booming development of various depth-dependent applications. However, depth maps suffer from the loss of valid values, which leads to holes and impairs both research and applications. In this paper, we propose a novel exemplar based method to fill depth holes and thus to improve depth quality. This novel method is based on the fact that a depth map has many similar even identical parts, and the lost depth values can be restored by referring to valid ones. Considering the intrinsic property of depth maps, i.e., the sharpness of object boundaries, we propose to use arbitrary-shape matching patches, instead of fixed squares, to avoid inter-depth-layer distortion and thus improve the boundary. In addition, since depth values do not have distinct features, cross-modal matching, where both depth and texture are involved, is utilized. Moreover, we also investigate the similarity criteria in cross-modal matching, in order to improve the accuracy between the source patch and the target patch. Experimental results demonstrate that the proposed method can accurately recover lost depth information, especially at boundaries, which outperforms state-of-the-art exemplar-based inpainting methods.
Function approximation with zonal function networks with activation functions analogous to the rectified linear unit functions

A zonal function (ZF) network on the q dimensional sphere Sq is a network of the form x↦∑k=1nakϕ(x⋅xk) where ϕ:[−1,1]→R is the activation function, xk∈Sq are the centers, and ak∈R. While the approximation properties of such networks are well studied in the context of positive definite activation functions, recent interest in deep and shallow networks motivate the study of activation functions of the form ϕ(t)=|t|, which are not positive definite. In this paper, we define an appropriate smoothness class and establish approximation properties of such networks for functions in this class. The centers can be chosen independently of the target function, and the coefficients are linear combinations of the training data. The constructions preserve rotational symmetries.
Copper prospectivity in Tibet, China: Based on the identification of geochemical anomalies

The Qinghai–Tibet Plateau is an important mineral-rich region and is well known for its copper resources. This study investigates stream-sediment geochemistry in assessing the potential for Cu resources in the region. A spectrum–area model is used to process large volumes of data with multifractal and power-spectrum analysis. The model can be used to separate geochemical anomalies from geochemical background levels thus eliminating the influence of different geomorphological landscapes. It is recognised from this study that geochemical anomalies are closely related to deep-seated faults forming terrane boundaries that are multiply deformed and intruded by granites. Second order structures related to these tectonic zones are commonly mineralised and are considered highly prospective for mineral resources. The results of this study indicate that geochemical anomalies are useful for identifying potential Cu mineral resources.
Bandwidth and Energy Efficient Image Sharing for Situation Awareness in Disasters

In order to save human lives and reduce injury and property loss, Situation Awareness (SA) information is essential and important for rescue workers to perform the effective and timely disaster relief. The information is generally derived from the shared images via widely used smartphones. However, conventional smartphone-based image sharing schemes fail to efficiently meet the needs of SA applications due to two main reasons, i.e., real-time transmission requirement and application-level image redundancy, which is exacerbated by limited bandwidth and energy availability. In order to provide efficient image sharing in disasters, we propose a bandwidth- and energy- efficient image sharing system, called BEES. The salient feature behind BEES is to propose the concept of Approximate Image Sharing (AIS), which explores and exploits approximate feature extraction, redundancy detection, and image uploading to trade the slightly low quality of computation results in content-based redundancy elimination for higher bandwidth and energy efficiency. Nevertheless, the boundaries of the tradeoffs between the quality of computation results and efficiency are generally subjective and qualitative. We hence propose the energy-aware adaptive schemes in AIS to leverage the physical energy availability to objectively and quantitatively determine the tradeoffs between the quality of computation results and efficiency. Moreover, unlike existing work only for cross-batch similar images, BEES further eliminates in-batch ones via a similarity-aware submodular maximization model. The response time of querying similar images is reduced via leveraging a geographic coordinate based index partitioning scheme. We have implemented the BEES prototype which is evaluated via three real-world image datasets. Extensive experimental results demonstrate the efficacy and efficiency of BEES. We have released the source codes of BEES at GitHub.
Design of a K-Winners-Take-All Model With a Binary Spike Train

A continuous-time K -winners-take-all (KWTA) neural model that can identify the largest K of N inputs, where command signal is described. The model is given by a differential equation where the spike train is a sum of delta functions. A functional block-diagram of the model includes N feed-forward hard-limiting neurons and one feedback neuron, used to handle input dynamics. The existence and uniqueness of the model steady states are analyzed, the convergence analysis of the state variable trajectories to the KWTA operation is proven, the convergence time and number of spikes required are derived, as well as the processing of time-varying inputs and perturbations of the model nonlinearities are analyzed. The main advantage of the model is that it is not subject to the intrinsic convergence of speed limitations of comparable designs. The model also has an arbitrary finite resolution determined by a given parameter, low complexity, and initial condition independence. Applications of the model for parallel sorting and parallel rank-order filtering are presented. Theoretical results are derived and illustrated with computer-simulated examples that demonstrate the model's performance.
Parana: A Parallel Neural Architecture Considering Thermal Problem of 3D Stacked Memory

Recent advances in deep learning (DL) have stimulated increasing interests in neural networks (NN). From the perspective of operation type and network architecture, deep neural networks can be categorized into full convolution-based neural network (ConvNet), recurrent neural network (RNN), and fully-connected neural network (FCNet). Different types of neural networks are usually cascaded and combined as a hybrid neural network (Hybrid-NN) to complete real-life cognitive tasks. Such hybrid-NN implementation is memory-intensive with large number of memory accesses, hence the performance of hybrid-NN is often limited by the insufficient memory bandwidth. A “3D + 2.5D” integration system, which integrates a high-bandwidth 3D stacked DRAM side-by-side with a highly-parallel neural processing unit (NPU) on a silicon interposer, overcomes the bandwidth bottleneck in hybrid-NN acceleration. However, intensive concurrent 3D DRAM accesses produced by the NPU lead to a serious thermal problem in 3D DRAM. In this paper, we propose a neural processor called <i>Parana</i> for hybrid-NN acceleration in consideration of thermal problem of 3D DRAM. Parana solves the thermal problem of 3D memory by optimizing both the total number of memory accesses and memory accessing behaviors. For memory accessing behaviors, Parana balances the memory bandwidth by spatial division mapping hybrid-NN onto computing resources, which efficiently avoids that masses of memory accesses are issued in a short time period. To reduce the total number of memory accesses, we design a new NPU architecture and propose a memory-oriented tiling and scheduling mechanism to exploit the maximum utilization of on-chip buffer. Experimental results show that Parana reduces the peak temperature by up to 54.72 <inline-formula> <tex-math notation="LaTeX">$^\circ$</tex-math></inline-formula> C and the steady temperature by up to 32.27 <inline-formula><tex-math notation="LaTeX"> $^\circ$</tex-math></inline-formula> C over state-of-the-art accelerators with 3D memory without performance degradation.
Safe option-critic: learning safety in the option-critic architecture

Designing hierarchical reinforcement learning algorithms that exhibit safe behaviour is not only vital for practical applications but also, facilitates a better understanding of an agent's decisions. We tackle this problem in the options framework, a particular way to specify temporally abstract actions which allow an agent to use sub-policies with start and end conditions. We consider a behaviour as safe that avoids regions of state-space with high uncertainty in the outcomes of actions. We propose an optimization objective that learns safe options by encouraging the agent to visit states with higher behavioural consistency. The proposed objective results in a trade-off between maximizing the standard expected return and minimizing the effect of model uncertainty in the return. We propose a policy gradient algorithm to optimize the constrained objective function. We examine the quantitative and qualitative behaviour of the proposed approach in a tabular grid-world, continuous-state puddle-world, and three games from the Arcade Learning Environment: Ms.Pacman, Amidar, and Q*Bert. Our approach achieves a reduction in the variance of return, boosts performance in environments with intrinsic variability in the reward structure, and compares favorably both with primitive actions as well as with risk-neutral options.
U-Finger: Multi-Scale Dilated Convolutional Network for Fingerprint Image Denoising and Inpainting

This paper studies the challenging problem of fingerprint image denoising and inpainting. To tackle the challenge of suppressing complicated artifacts (blur, brightness, contrast, elastic transformation, occlusion, scratch, resolution, rotation, and so on) while preserving fine textures, we develop a multi-scale convolutional network termed U-Finger. Based on the domain expertise, we show that the usage of dilated convolutions as well as the removal of padding have important positive impacts on the final restoration performance, in addition to multi-scale cascaded feature modules. Our model achieves the overall ranking of No.2 in the ECCV 2018 Chalearn LAP Inpainting Competition Track 3 (Fingerprint Denoising and Inpainting). Among all participating teams, we obtain the MSE of 0.0231 (rank 2), PSNR 16.9688 dB (rank 2), and SSIM 0.8093 (rank 3) on the hold-out testing set.
Bayesian analysis for mixture of latent variable hidden Markov models with multivariate longitudinal data

Latent variable hidden Markov models (LVHMMs) are important statistical methods in exploring the possible heterogeneity of data and explaining the pattern of subjects moving from one group to another over time. Classic subject- and/or time-homogeneous assumptions on transition matrices in transition model as well as the emission distribution in the observed process may be inappropriate to interpret heterogeneity at the subject level. For this end, a general extension of LVHMM is proposed to address the heterogeneity of multivariate longitudinal data both at the subject level and the occasion level. The main modeling strategy is that the observed time sequences are first grouped into different clusters, and then within each cluster the observed sequences are formulated via latent variable hidden Markov model. The local heterogeneity at the occasion level is characterized by the distribution related to the latent states, while the global heterogeneity at the subject level is identified with the finite mixture model. Compared to the existing methods, an appeal underlying the proposal is its capacity of accommodating non-homogeneous patterns of state sequences and emission distributions across the subjects simultaneously. As a result, the proposal provides a comprehensive framework for exploring various kinds of relevance among the multivariate longitudinal data. Within the Bayesian paradigm, Markov Chains Monte Carlo (MCMC) method is used to implement posterior analysis. Gibbs sampler is used to draw observations from the related full conditionals and posterior inferences are carried out based on these simulated observations. Empirical results including simulation studies and a real example are used to illustrate the proposed methodology.
Cartesian and Lyndon trees

The article describes the structural and algorithmic relations between Cartesian trees and Lyndon trees. This leads to a uniform presentation of the Lyndon table of a word corresponding to the Next Nearest Smaller table of a sequence of numbers. It shows how to efficiently compute runs, that is, maximal periodicities occurring in a word.