Miracle-dz/UniFAR-FTUs huggingface dataset:
Joint User Mobility and Traffic Characterization in Temporary Crowded Events

In TCEs (Temporary Crowded Events), for example, music festivals, users are faced with problems accessing the Internet. TCEs are limited time events with a high concentration of people moving within the event enclosure while accessing the Internet. Unlike other events where the user locations are constant and known at the start (e.g. stadiums), the traffic generation and the user movement in TCEs is variable and influenced by the dynamics of the event. The movement of users can lead to overloads in APs (Access Point) in case they are fixed. In order to minimize this phenomenon, new techniques have been explored that resort to the adjustable positioning of APs integrated into UAVs (Unmanned Aerial Vehicles). In these scenarios, the dynamic of the location of the APs requires that tools of prediction of the users movements and, in turn, of the sources of traffic, gain particular expression when being related to the algorithms of positioning of the referred APs. In order to allow the development and analysis of new network planning solutions for TCEs, it is necessary to recreate these scenarios in simulation, which, in turn, requires a detailed characterization of this kind of events. This article aims to characterize and model the mobility and traffic generated by users in TCEs. This characterization will enable the development of new statistical models of traffic generation and user mobility in TCEs.
Deformation and sorting of capsules in a T-junction

We study experimentally the motion and deformation of individual capsules transported by a constant volume-flux flow of low Reynolds number, through the T-junction of a channel with rectangular cross-section. We use millimetric ovalbumin-alginate capsules which we characterise independently of the flow experiment. Centred capsules travel at constant velocity down the straight channel leading to the T-junction, where they decelerate and expand in the spanwise direction before turning into one of the two identical daughter channels. There, non-inertial lift forces act to re-centre them and relax their shape until they reach a steady state of propagation. We find that the dynamics of fixed-size capsules within our channel geometry is governed by a capillary number $Ca$ defined as the ratio of viscous shear forces to elastic restoring forces, which we quantify by statically compressing the capsule between parallel plates to 50 % of its initial diameter, in order to account for different membrane thickness, pre-inflation and nonlinear elastic deformation. We show that the maximum extension in the T-junction of capsules of different stiffness collapses onto a master curve in $Ca$. This provides a sensitive measure of the relative stiffness of capsules at constant flow rate, particularly for softer capsules. We also find that the T-junction can sort fixed-size capsules according to their stiffness because the position in the T-junction from which capsules are entrained into the daughter channel depends uniquely on $Ca$. We demonstrate that a T-junction can be used as a sorting device by enhancing this initial capsule separation through a diffuser.
Dislocation drag from phonon wind in an isotropic crystal at large velocities

ABSTRACT The anharmonic interaction and scattering of phonons by a moving dislocation, the photon wind, imparts a drag force on the dislocation. In early studies, the drag coefficient B was computed and experimentally determined only for dislocation velocities v much less than transverse sound speed, . In this paper, we derive analytic expressions for the velocity dependence of B up to in terms of the third-order continuum elastic constants of an isotropic crystal, in the continuum Debye approximation. In so doing we point out that the most general form of the third order elastic potential for such a crystal and the dislocation-phonon interaction requires two additional elastic constants involving asymmetric local rotational strains, which have been neglected previously. We compute the velocity dependence of the transverse phonon wind contribution to B in the range 1–90% for Al, Cu, Fe, and Nb in the isotropic Debye approximation. The drag coefficient for transverse phonons scattering from screw dislocations is finite as , whereas B is divergent for transverse phonons scattering from edge dislocations in the same limit. This divergence indicates the breakdown of the Debye approximation and sensitivity of the drag coefficient at very high velocities to the microscopic crystalline lattice cutoff. We compare our results to experimental results wherever possible and identify ways to validate and further improve the theory of dislocation drag at high velocities with realistic phonon dispersion relations, inclusion of lattice cutoff effects, MD simulation data, and more accurate experimental measurements.
Far-infrared Properties of the Bright, Gravitationally Lensed Quasar J0439+1634 at z = 6.5

We present IRAM NOrthern Extended Millimeter Array, James Clerk Maxwell Telescope/Submillimetre Common-User Bolometer Array-2 and Very Large Array (VLA) observations of the most distant known gravitationally lensed quasar, J0439+1634 at z = 6.5. We detect strong dust emission, [C ii] 158 μm, [C i] 369 μm, [O i] 146 μm, CO(6–5), CO(7–6), CO(9–8), CO(10–9), H2O 31,2−22,1, and H2O 32,1−31,2 lines, as well as a weak radio continuum. The strong [C ii] line yields a systemic redshift of the host galaxy to be z = 6.5188 ± 0.0002. The magnification makes J0439+1634 the far-infrared (FIR) brightest quasar at z > 6 known, with the brightest [C ii] line yet detected at this redshift. The FIR luminosity is (3.4 ± 0.2) × 1013μ−1 L⊙, where μ ∼2.6–6.6 is the magnification of the host galaxy, estimated based on the lensing configuration from HST imaging. We estimate the dust mass to be (2.2 ± 0.1) × 109μ−1 . The CO spectral line energy distribution using four CO lines are best fit by a two-component model of the molecular gas excitation. The estimates of molecular gas mass derived from CO lines, and atomic carbon mass are consistent, in the range of (3.9–8.9) × 1010μ−1 . The [C ii]/[C i], [C ii]/CO, and [O i]/[C ii] line luminosity ratios suggest a photodissociation region model with more than one component. The ratio of H2O 32,1−31,2 line luminosity to LTIR is consistent with values in local and high-redshift ultra-/hyper-luminous infrared galaxies. The VLA observations reveal an unresolved radio continuum source, and indicate that J0439+1634 is a radio-quiet quasar with R = 0.05–0.17.
Calibration of the virial factor f in supermassive black hole masses of reverberation-mapped AGNs

Using a compiled sample of 34 broad-line active galactic nuclei (AGNs) with measured H β time lags from the reverberation mapping (RM) method and measured bulge stellar velocity dispersions σ*, we calculate the virial factor f by assuming that the RM AGNs intrinsically obey the same MBH−σ* relation as quiescent galaxies, where MBH is the mass of the supermassive black hole (SMBH). Considering four tracers of the velocity of the broad-line regions (BLRs), i.e. the H β line width or line dispersion from the mean or rms spectrum, there are four kinds of the factor f. Using the H β full width at half-maximum (FWHM) to trace the BLRs velocity, we find significant correlations between the factor f and some observational parameters, e.g. FWHM, the line dispersion. Using the line dispersion to trace the BLRs velocity, these relations disappear or become weaker. It implies the effect of inclination in BLRs geometry. It also suggests that the variable f in MBH estimated from luminosity and FWHM in a single-epoch spectrum is not negligible. Using a simple model of thick-disc BLRs, we also find that, as the tracer of the BLRs velocity, H β FWHM has some dependence on the inclination, while the line dispersion σH β is insensitive to the inclination. Considering the calibrated FWHM-based factor f from the mean spectrum, the scatter of the SMBH mass is 0.39 dex for our sample of 34 low-redshift RM AGNs. For a high-redshift sample of 30 Sloan Digital Sky Survey RM AGNs with measured stellar velocity dispersions, we find that the SMBH mass scatter is larger than that for our sample of 34 low-redshift RM AGNs. It implies the possibility of evolution of the MBH−σ* relation from high-redshift to low-redshift AGNs.
Translation and rotation of a spherical particle in a turbulent boundary layer

Three-dimensional particle tracking experiments were conducted in a turbulent boundary layer with friction Reynolds number $Re_\tau$ of 700 and 1300. Two finite size spheres with specific gravities of 1.003 (P1) and 1.050 (P2) and diameters of 60 and 120 wall units were released individually from rest on a smooth wall. The spheres were marked with dots all over the surface to monitor their translation and rotation via high-speed stereoscopic imaging. The spheres accelerated strongly after release over streamwise distances of one boundary layer thickness before approaching an approximate terminal velocity. Initially, sphere P1, which had Reynolds numbers $Re_p$ of 800 and 1900, always lifts off from the wall. Similar behavior was observed occasionally for sphere P2 with initial $Re_p$ of 1900. The spheres that lifted off reached an initial peak in height before descending towards the wall. The sphere trajectories exhibited multiple behaviors including saltation, resuspension and sliding motion with small random bouncing depending on both $Re_\tau$ and specific gravity. The lighter sphere at $Re_\tau=1300$, which remained suspended above the wall during most of its trajectory, propagated with the fastest streamwise velocity. By contrast, the denser sphere at $Re_\tau=700$, which mostly slid along the wall, propagated with the slowest streamwise velocity. After the spheres approached an approximate terminal velocity, many experienced additional lift-off events that were hypothesized to be driven by hairpins or coherent flow structures. Spheres were observed to rotate about all three coordinate axes. While the mean shear may induce a rotation about the spanwise axis, near-wall coherent structures and the sphere's wake might drive the streamwise and wall-normal rotations. In all cases where the sphere propagates along the wall, sliding motion, rather than forward rolling motion, is dominant.
hammurabi X: Simulating Galactic Synchrotron Emission with Random Magnetic Fields

We present version X of the hammurabi package, the HEALPix-based numeric simulator for Galactic polarized emission. Improving on its earlier design, we have fully renewed the framework with modern C++ standards and features. Multithreading support has been built in to meet the growing computational workload in future research. For the first time, we present precision profiles of the hammurabi line-of-sight integral kernel with multilayer HEALPix shells. In addition to fundamental improvements, this report focuses on simulating polarized synchrotron emission with Gaussian random magnetic fields. Two fast methods are proposed for realizing divergence-free random magnetic fields either on the Galactic scale where field alignment and strength modulation are imposed, or on a local scale where more physically motivated models like a parameterized magnetohydrodynamic (MHD) turbulence can be applied. As an example application, we discuss the phenomenological implications of Gaussian random magnetic fields for high Galactic latitude synchrotron foregrounds. In this, we numerically find B/E polarization-mode ratios lower than unity based on Gaussian realizations of either MHD turbulent spectra or in spatially aligned magnetic fields.
Directivity Modes of Earthquake Populations with Unsupervised Learning

We present a novel approach for resolving modes of rupture directivity in large populations of earthquakes. A seismic spectral decomposition technique is used to first produce relative measurements of radiated energy for earthquakes in a spatially compact cluster. The azimuthal distribution of energy for each earthquake is then assumed to result from one of several distinct modes of rupture propagation. Rather than fitting a kinematic rupture model to determine the most likely mode of rupture propagation, we instead treat the modes as latent variables and learn them with a Gaussian mixture model. The mixture model simultaneously determines the number of events that best identify with each mode. The technique is demonstrated on four datasets in California, each with compact clusters of several thousand earthquakes with comparable slip mechanisms. We show that the datasets naturally decompose into distinct rupture propagation modes that correspond to different rupture directions, and the fault plane is unambiguously identified for all cases. We find that these small earthquakes exhibit unilateral ruptures 63–73% of the time on average. The results provide important observational constraints on the physics of earthquakes and faults.
Algorithms for Weighted Independent Transversals and Strong Colouring

An independent transversal (IT) in a graph with a given vertex partition is an independent set consisting of one vertex in each partition class. Several sufficient conditions are known for the existence of an IT in a given graph and vertex partition, which have been used over the years to solve many combinatorial problems. Some of these IT existence theorems have algorithmic proofs, but there remains a gap between the best existential bounds and the bounds obtainable by efficient algorithms. Recently, Graf and Haxell (2018) described a new (deterministic) algorithm that asymptotically closes this gap, but there are limitations on its applicability. In this article, we develop a randomized algorithm that is much more widely applicable, and demonstrate its use by giving efficient algorithms for two problems concerning the strong chromatic number of graphs.
DIEL: Transparent Scaling for Interactive Visualization

We live in an era of big data and rich data visualization. As data sets increase in size, browser-based interactive visualizations eventually hit limits in storage and processing capacity. In order to provide interactivity over large datasets, visualization applications typically need to be extensively rewritten to make use of powerful back-end services. It would be far preferable if front-end developers could write visualizations once in a natural way, and have a framework take responsibility for transparently scaling up the visualization to use back-end services as needed. Achieving this goal requires rethinking how communication and state are managed by the framework: the mapping of interaction logic to server APIs or database queries, handling of results arriving asynchronously over the network, as well as basic cross-layer performance optimizations like caching. In this paper, we present DIEL, a framework that achieves this cross-layer autoscaling transparently under a simple, declarative interface. DIEL treats UI events as a stream of data that is captured in an event history for reuse. Developers declare what the state of the interface should be after the arrival of events. DIEL compiles these declarative specifications into relational queries over both event history and the data to be visualized. In doing so, DIEL makes it easier to develop visualizations that are robust against changes to the size and location of data. To evaluate the DIEL framework, we developed a prototype implementation and confirmed that DIEL supports a range of visualization and interaction designs. Visualizations written using DIEL can transparently and seamlessly scale to use back-end services with little intervention from the developer.
Gravitational wave array -- operation of the LIGO-Virgo network as a gravitational wave Hanbury Brown and Twiss interferometer

The current gravitational wave observatory network includes detectors at Hanford, Livingston, and Cascina. This network could be used as a gravitational wave Hanbury Brown and Twiss (HBT) interferometer. The gravitational wave HBT interferometer is an extension of conventional HBT intensity interferometers for Standard Model fields, since gravitational wave detectors measure amplitude instead of intensity. Glauber correlations in the GWA have a wide range of potential applications, such as determining the properties of a gravitational wave source. These correlations also have the potential of demonstrating and measuring non-classicality, i.e. the quantum nature, of the gravitational wave.
A Kernel Stein Test for Comparing Latent Variable Models

We propose a kernel-based nonparametric test of relative goodness of fit, where the goal is to compare two models, both of which may have unobserved latent variables, such that the marginal distribution of the observed variables is intractable. The proposed test generalizes the recently proposed kernel Stein discrepancy (KSD) tests (Liu et al., Proceedings of the 33rd international conference on machine learning (pp. 276–284); Chwialkowski et al., (2016), In Proceedings of the 33rd international conference on machine learning (pp. 2606–2615); Yang et al., (2018), In Proceedings of the 35th international conference on machine learning (pp. 5561–5570)) to the case of latent variable models, a much more general class than the fully observed models treated previously. The new test, with a properly calibrated threshold, has a well-controlled type-I error. In the case of certain models with low-dimensional latent structures and high-dimensional observations, our test significantly outperforms the relative maximum mean discrepancy test, which is based on samples from the models and does not exploit the latent structure.
On First-Order Bounds, Variance and Gap-Dependent Bounds for Adversarial Bandits

We make three contributions to the theory of k-armed adversarial bandits. First, we prove a first-order bound for a modified variant of the INF strategy by Audibert and Bubeck [2009], without sacrificing worst case optimality or modifying the loss estimators. Second, we provide a variance analysis for algorithms based on follow the regularised leader, showing that without adaptation the variance of the regret is typically {\Omega}(n^2) where n is the horizon. Finally, we study bounds that depend on the degree of separation of the arms, generalising the results by Cowan and Katehakis [2015] from the stochastic setting to the adversarial and improving the result of Seldin and Slivkins [2014] by a factor of log(n)/log(log(n)).
Fast approximate clearance evaluation for rovers with articulated suspension systems

We present a light‐weight body‐terrain clearance evaluation algorithm for the automated path planning of NASA's Mars 2020 rover. Extraterrestrial path planning is challenging due to the combination of terrain roughness and severe limitation in computational resources. Path planning on cluttered and/or uneven terrains requires repeated safety checks on all the candidate paths at a small interval. Predicting the future rover state requires simulating the vehicle settling on the terrain, which involves an inverse‐kinematics problem with iterative nonlinear optimization under geometric constraints. However, such expensive computation is intractable for slow spacecraft computers, such as RAD750, which is used by the Curiosity Mars rover and upcoming Mars 2020 rover. We propose the approximate clearance evaluation (ACE) algorithm, which obtains conservative bounds on vehicle clearance, attitude, and suspension angles without iterative computation. It obtains those bounds by estimating the lowest and highest heights that each wheel may reach given the underlying terrain, and calculating the worst‐case vehicle configuration associated with those extreme wheel heights. The bounds are guaranteed to be conservative, hence ensuring vehicle safety during autonomous navigation. ACE is planned to be used as part of the new onboard path planner of the Mars 2020 rover. This paper describes the algorithm in detail and validates our claim of conservatism and fast computation through experiments.
Geodesic Centroidal Voronoi Tessellations: Theories, Algorithms and Applications

Nowadays, big data of digital media (including images, videos and 3D graphical models) are frequently modeled as low-dimensional manifold meshes embedded in a high-dimensional feature space. In this paper, we summarized our recent work on geodesic centroidal Voronoi tessellations(GCVTs), which are intrinsic geometric structures on manifold meshes. We show that GCVT can find a widely range of interesting applications in computer vision and graphics, due to the efficiency of search, location and indexing inherent in these intrinsic geometric structures. Then we present the challenging issues of how to build the combinatorial structures of GCVTs and establish their time and space complexities, including both theoretical and algorithmic results.
Constructing Information-Lossless Biological Knowledge Graphs from Conditional Statements

Conditions are essential in the statements of biological literature. Without the conditions (e.g., environment, equipment) that were precisely specified, the facts (e.g., observations) in the statements may no longer be valid. One biological statement has one or multiple fact(s) and/or condition(s). Their subject and object can be either a concept or a concept's attribute. Existing information extraction methods do not consider the role of condition in the biological statement nor the role of attribute in the subject/object. In this work, we design a new tag schema and propose a deep sequence tagging framework to structure conditional statement into fact and condition tuples from biological text. Experiments demonstrate that our method yields a information-lossless structure of the literature.
Exploring learner perceptions of and interaction behaviors using the Research Writing Tutor for research article Introduction section draft analysis

The swiftly escalating popularity of automated writing evaluation (AWE) software in recent years has compelled much study into its potential for effective pedagogical use (Chen & Cheng, 2008; Cotos, 2011; Warschauer & Ware, 2006). Research on the effectiveness of AWE tools has concentrated primarily on determining learners’ achieved output (Warschauer & Ware, 2006) and emphasized the attainment of linguistic goals (Escudier et al., 2011); however, in-process investigations of users’ interactions with and perceptions of AWE tools remain sparse (Shute, 2008; Ware, 2011). This dissertation employed a mixed-methods approach to investigate how 11 graduate student language learners interacted with and perceived the Research Writing Tutor (RWT), a web-based AWE tool which provides discourse-oriented, discipline-specific feedback on users’ section drafts of empirical research papers. A variety of data was collected and analyzed to capture a multidimensional depiction of learners’ first time interactions with the RWT; data comprised learners’ pre-task demographic survey responses, screen recordings of students’ interactions with the RWT, individual users’ interactional reports archived in the RWT database, instructor and researcher observations of students’ in-class RWT interactions, stimulated recall transcripts, and post-task survey responses. Descriptive statistics of the Likert-scale response data were calculated, and open-ended survey responses and stimulated recall transcripts were analyzed using open coding discourse analysis techniques or Systemic Functional Linguistic (SFL) appreciation resource analysis (Martin & Rose, 2003), prior to triangulating data for certain research questions. Results showed that participants found the RWT to be useful and were positive in their attitudes about helpfulness of the tool in the future if issues in feedback accuracy were improved. However, the participants’ also cited wavering trust in the RWT and its automated feedback, seemingly originating from learners’ observations of RWT