Miracle-dz/UniFAR-FTUs huggingface dataset:
Vehicle-Motion-Constraint-Based Visual-Inertial-Odometer Fusion With Online Extrinsic Calibration

Autonomous positioning in complex urban areas is a challenging problem and has attracted increasing attention in academia. Multisensor fusion of camera, inertial measurement unit (IMU), and wheel odometer has been a prevailing solution that is not only low-cost but easy-to-build. Most of the related methods fuse the odometer measurements into the visual-inertial framework by preintegrating the wheel speed into the displacement. However, they are not very suitable for some scenarios where the vehicle velocity changes frequently. Instead of preintegrating the odometer measurements, in this article, we present an efficient and practical visual-inertial-odometer approach that fuses the wheel speed into the visual-inertial framework directly based on the vehicle motion constraint. Specifically, we use the nonholonomic constraint (NHC) and lever-arm compensation to introduce the vehicle velocity measurement into the fusion framework to limit the drift. Meanwhile, the proposed framework also allows to online calibration of the IMU-odometer extrinsic parameters (EPs) explicitly. Moreover, we develop an observability-aware method to enhance the system stability and the performance of online extrinsic calibration. We also develop a robust initialization method to obtain the initial values of the visual-inertial-odometer system in one-step optimization. Our approach is validated extensively in simulation environments, autonomous driving public datasets, and real-world experiments. The simulation results show the extrinsic calibration error is within 0.1°/0.02 m for rotation and translation. The public dataset and real-world ground robot experiments show a 0.3% position error in both the 4-km long urban area route and the 403-m long park route.
PHYSICAL LAYER SECURITY IN THE 5G HETEROGENEOUS WIRELESS SYSTEM WITH IMPERFECT CSI

5G is expected to serve completely heterogeneous scenarios where devices with low or high software and hardware complexity will coexist. This entails a security challenge because low complexity devices such as IoT sensors must still have secrecy in their communications. This project proposes tools to maximize the secrecy rate in a scenario with legitimate users and eavesdroppers considering: i) the limitation that low complexity users have in computational power and ii) the eavesdroppers’ unwillingness to provide their channel state information to the base station. The tools have been designed based on the physical layer security field and solve the resource allocation from two different approaches that are suitable in different use cases: i) using convex optimization theory or ii) using classification neural networks. Results show that, while the convex approach provides the best secrecy performance, the learning approach is a good alternative for dynamic scenarios or when wanting to save transmitting power.
HYDRAULIC GEOMETRY OF ACTIVE GRAVEL RIVERS

The hydraulic geometry of straight reaches of wide, active rivers with beds and banks composed of loose gravel is considered. Naive mechanistic formulations lead to the stable channel paradox; stable width is incompatible with an active bed. A resolution of the paradox based on bed stress redistribution due to turbulent lateral transfer of downstream momentum is outlined and is used to obtain three rationally derived regime relations.These dimensionless relations provide channel properties as functions of bed pavement size and two specified variables, e.g., water and sediment discharge, or water discharge and width. Reduction to relations for hydraulic geometry is shown to require information concerning watershed mechanics that is external to the river, and thus fluvially indeterminate. An empirical relation is determined for this purpose, allowing for derivation of dimensionless relations for hydraulic geometry.
Human Geography and area Research

FIRST glance it might appear that only in physical geography would a A geographer make a contribution to an area research program staffed by social scientists. Geographers, however, do not so delimit their field. ' This paper focuses in particular on the contributions of human geography. In the treatment I present my own point of view, but am only too conscious that I neither reveal exclusively new thoughts nor, in the attempt to emphasize new ideas, cover all topics uniformly.2 As an example of the distinctive nature of human geography let us consider economic geography. This branch, Wooldridge and East observe, is in practice at least three quarters of the field of human geography and (rightly or wrongly) is not a branch of economics any more than is economic geology.3 Hartshorne, Finch, and others earlier indicated much the same opinion.4 Most topics studied by the economic geographer are also considered by economists in various specialist branches of that subject, but are not, however, core topics in economics. Some of the topics which the economic geographer studies include: various aspects of agriculture, mining, and other production; industrial location and development; transport routes and flows; markets; and rural and urban settlements. More nearly core topics for a relatively "pure" economist on the other hand include: price movements,
Critical Shields values in coarse‐bedded steep streams

Critical Shields values ( τc* ) suitable for specific applications are back‐calculated from representative bed load samples in mountain streams and a flow competence/critical flow approach. The general increase of τc50* (for the bed D50 size) as well as τc16* and τc84* (for the bed D16 and D84 sizes) with stream gradient Sx and also the stratification of τc50* by relative flow depth and relative roughness are confirmed. Critical Shields values τc16* are shown to exceed τc50* by about threefold, while those for τc84* are nearly half of τc50* . However, it remains unclear to what extent physical processes or numerical artifacts contribute to determining critical Shields values. Critical bankfull Shields values ( τcbf* ) back‐computed from the average largest particles mobile at bankfull flow DBmax,bf approach τc16* at steep gradients and τc84* at low gradients and therefore increase very steeply with Sx. The relation τcbf*=f(Sx) is stratified by bed stability (D50/DBmax,bf) and predictable if bed stability can be field categorized. Noncritical Shields values ( τbf50* ) computed from bankfull flow depth and the D50 size differ from τc50* and τcbf* . Only in bankfull mobile streams where D50/DBmax = 1 can τ*cbf, τc50* , and τbf50* be used interchangeably. In highly mobile streams, substituting τcbf* by τbf50* overpredicts the DBmax,bf size by up to fivefold and underpredicts DBmax,bf by the same amount in highly stable streams. A value of 0.03 is appropriate for τcbf* only on low stability beds with Sx ≅ 0.01, but overpredicts DBmax,bf by 30‐fold on highly stable beds with Sx ≅ 0.1. Differences in field and computational methods also affect critical Shields values.
Bayesian Inference with Missing Data

1 Bayesian Inference . 2 1.1 Main steps . 2 1.2 Some basic models . 4 2 Missing Data Problems . 10 2.1 Data augmentation . 10 2.2 Discrete data example . 11 2.3 Gaussian data example . 12 References . 14
Airborne hyperspectral BRDF measurements using the HyperSpecTIR instrument

The scan mechanism of the HyperSpecTIR hyperspectral instrument has been modified to allow BRDF measurements from an airborne platform. The HyperSpecTIR is a flexible, airborne hyperspectral imager capable of on-the-fly programmability. Such measurements afford the opportunity to study geometric and spectral properties of natural scenes such as fields and canopies, as well as man-made substances such as composite materials and paints. As a proof of concept study for the BRDF measurement method, data was collected during flight operations near Phoenix Arizona. The measurements were performed in the principle plane and included the solar hot-spot. Detailed descriptions of the instrument and data collection methods are presented. The collected data is analyzed and compared to BRDF models of the solar hot-spot.
Geometric characteristics of pull-apart basins

Pull-apart basins are depressions bounded on their sides by two or more strike-slip faults and on their ends by diagonal transfer faults. As proposed by theoretical, experimental, and numerical studies in the literature, there are angular and scale relationships between these faults. Here, I compiled the major results on geometries of pull-apart basins of previous workers and then examined the geometric characteristics of pull-apart basins along the North Anatolian fault zone for a comparison of current data in two and three dimensions. According to the results of my compilation from the literature and measurements of pull-apart examples from northern Turkey, the acute angles of this type of strike-slip basin are clustered at 30°–35°. In metric scale, the consistency in their two-dimensional (2-D) geometry is well known as an aspect ratio of 3:1 between length and width. Basin length is a function of stretching associated with strike-slip displacement, and increased displacement causes the width of the fault zone to increase, resulting in wider pull-apart basins. However, the depth of a pull-apart basin is a function of stretching associated with strike-slip displacement. In this study, comparison of data related to pull-apart basin scales from the literature suggests that the depth is related to the length and width.
Elastic constants measurement in anisotropic Olivier wood plates using air-coupled ultrasonic bulk waves.

The anisotropic materials are widely used for many structural applications, the determination of mechanical properties is critical for ensuring reliable performance. The knowledge of complete elastic stiffness matrix is essential for modelling and evaluating the mechanical behaviour of materials under severe loading conditions. Ultrasonic techniques are however qualified for non destructive measurement of all of the elastic constants of such materials. The elastic moduli Cij identification from the measurement of phase velocities of Lamb modes were often deduced from the low-frequency plate wave dispersion data, using contact transducers or Laser. There are two disadvantages of the techniques, first the non diagonal elastic constants Cij are difficult to measure and second the coupling resin might change the elastic properties of the materials. Air coupled transducers are now advanced enough to be used in the industry field and it was proved in the past that they are efficient enough to generate Lamb waves in plates and to detect them after propagation. The system is tested for anisotropic composite materials made of epoxy matrix reinforced by glass or carbon fibres. In this work we used this technique to determine the anisotropic constants of anisotropic olivier wood plates. We are now investigating the inverse problem for the identification of Cij from phase velocities of any Lamb modes. The optimization process, applying the simplex method, gives the values of elastic constants with uncertainty in the vicinity of 15 percent.
Prey density drives diet shift of the invasive mysid shrimp, Limnomysis benedeni

Understanding the diet preferences and prey selection of invasive species is crucial to better predict their impact on community structure and ecosystem functioning. Limnomysis benedeni, a Ponto-Caspian invasive mysid shrimp, is one of the most successful invaders in numerous European river and lake ecosystems. While existing studies suggest potentially strong trophic impact due to high predation pressure on invaded plankton communities, little is known of its prey selectivity between phyto-and zooplankton, under diﬀerent prey concentrations. Here, we therefore investigated the feeding selectivity of L. benedeni on two commonly occurring prey organisms in freshwaters, the small rotifer zooplankton Brachionus calyciﬂorus together with the microphytoplankton Cryptomonas sp. present in increasing densities. Our results demonstrated a clear shift in diet selection, with L. benedeni switching from B. calyciﬂorus to Cryptomonas sp. already when the two prey species were provided in equal biomasses. Diﬀerent functional responses were observed for each prey type, indicating somewhat diﬀerent foraging mechanisms for each prey type. These ﬁndings provide experimental evidence on the feeding ﬂexibility of invasive mysid shrimps and potential implications for trophic interactions in invaded ecosystems.
A multicomponent model of phytoplankton size structure

Size-fractionated filtration (SFF) is a direct method for estimating pigment concentration in various size classes. It is also common practice to infer the size structure of phytoplankton communities from diagnostic pigments estimated by high-performance liquid chromatography (HPLC). In this paper, the three-component model of Brewin et al. (2010) was fitted to coincident data from HPLC and from SFF collected along Atlantic Meridional Transect cruises. The model accounted for the variability in each data set, but the fitted model parameters differed for the two data sets. Both HPLC and SFF data supported the conceptual framework of the three-component model, which assumes that the chlorophyll concentration in small cells increases to an asymptotic maximum, beyond which further increase in chlorophyll is achieved by the addition of larger celled phytoplankton. The three-component model was extended to a multicomponent model of size structure using observed relationships between model parameters and assuming that the asymptotic concentration that can be reached by cells increased linearly with increase in the upper bound on the cell size. The multicomponent model was verified using independent SFF data for a variety of size fractions and found to perform well (0.628 ≤ r ≤ 0.989) lending support for the underlying assumptions. An advantage of the multicomponent model over the three-component model is that, for the same number of parameters, it can be applied to any size range in a continuous fashion. The multicomponent model provides a useful tool for studying the distribution of phytoplankton size structure at large scales.
The correlated evolution of foraging mode and reproductive in lizards

Life-history theory suggests that the optimal reproductive effort of an organism is affected by factors such as energy acquisition and predation risk. The observation that some organisms actively search for their prey and others ambush them creates the expectation of different energy needs and predation risk associated with each foraging behavior, the so-called “foraging-mode paradigm”. Although this paradigm has been around for decades, the empirical evidence consists of conflicting results derived from competing models based on different mechanisms. For instance, models within the foraging-mode paradigm suggest that widely-foraging females have evolved low reproductive effort, because a heavy reproductive load decreases their ability to escape from predators. By contrast, a long-standing prediction of evolutionary theory indicates that organisms subject to high extrinsic mortality, should invest more in reproduction. Here, we present the first partial evidence that widely-foraging species have evolved greater reproductive effort than have sit-and-wait species, which we attribute to a larger body size and greater mortality among mobile foragers. According to our findings, we propose a theoretical model that could explain the observed pattern in lizards, suggesting ways for evolutionary ecologists to test mechanistic hypotheses at the intraspecific level.
LABOUR RELATIONS DEVELOPMENT AND CHANGES IN DIGITAL ECONOMY: FROM FRAGILE HUMAN RESOURCES TO AGILE TALENT-COLLABORATORS

Citation Information: Sánchez-Bayón, A. , Lominchar, J. (2020). Labour relations development and changes in digital economy: from fragile human resources to agile talent-collaborators. Journal of Legal, Ethical and Regulatory Issues, x(x). ABSTRACT This article aims to be a phenomenological critical review, with comparative and holistic techniques, about the labour relations development into the welfare state economy and the changes in the digital economy. There is a diagnosis, in ethical, compliance and lean terms, in the process to move from a model of human resources in bureaucratic corporations to a talent development in agile organizations. Also, it is offered a profile of the new kind of collaborators in digital era.
Multivariate models for rainfall based on Markov modulated Poisson processes

Point process models for rainfall are constructed generally based on Poisson cluster processes. Most commonly used point process models in the literature were constructed either based on Bartlett–Lewis or Neyman–Scott cluster processes. In this paper, we utilize a class of Cox process models, termed the Markov modulated Poisson process (MMPP), to model rainfall intensity. We use this class of models to analyse rainfall data observed in the form of tip time series from rain gauge tipping buckets in a network of gauges in Somerset, southwest England, recorded by the Hydrological Radar Experiment (HYREX). Univariate and multivariate models are employed to analyse the data recorded at single and multiple sites in the catchment area. As the structure of this proposed class of MMPP models allows us to construct the likelihood function of the observed tip time series, we utilize the maximum likelihood methods in our analysis to make inferences about the rainfall intensity at sub-hourly time scales. The multivariate models are used to analyse rainfall time series jointly at four stations in the region. Properties of the cumulative rainfall in discrete time intervals are studied, and the results of fitting three-state models are presented.
Can the Paths of Successful Students Help Other Students With Their Course Enrollments?

In this paper, we present an extended evaluation of a course recommender system designed to support students who struggle in the first semesters of their studies and are at risk of dropping out. The system, which was developed in earlier work using a student-centered design and which is based on the explainable k -nearest neighbor algorithm, recommends a set of courses that have been passed by the majority of the student’s nearest neighbors who have completed their studies. The present evaluation is based on the data of students from three different study programs. One result is that the recommendations do lower the dropout risk. We also discovered that while the recommended courses differed from those taken by students who dropped out, they matched quite well with courses taken by students who completed the degree program. Although the course recommender sys-tem targets primarily students at risk, students doing well could use it. Furthermore, we found that the number of recommended courses for struggling students is less than the number of courses they actually enrolled in. This suggests that the recommendations given indicate a different and hopefully feasible path through the study program for students at risk of dropping out.
Hygroscopicity and cloud droplet activation of mineral dust aerosol

Hygroscopicity and cloud condensation nucleus (CCN) activity were measured for three mineral dust samples: one from the Canary Islands, representing North African dust transported across the Atlantic; one from outside Cairo, representing North African dust transported to the eastern Mediterranean; and Arizona Test Dust, representing dust in the southwestern United States. To reaerosolize bulk samples, dust samples were either suspended in high purity water and particles generated by atomization, or samples were resuspended in dry air using a fluidized bed. Only the Canary Island sample generated from aqueous suspension showed appreciable hygroscopic growth at subsaturated conditions; all other samples exhibited diameter growth factors of less than 1.1 for relative humidities ≤90%. Despite their low hygroscopicities at subsaturated conditions, all samples activated as cloud droplets at supersaturations lower than required for insoluble particles. We suggest that the CCN activity of these mineral dusts are well‐represented using the hygroscopicity parameter 0.01 ≤ κ ≤ 0.08.
Quantification of vibrations during mountain biking

Background: Â During cross-country mountain biking, riders are subjected to vibrations due to the terrain, which must be damped before reaching the central nervous system. Â Damping vibrations requires work, which may help to explain the decrease in economy for mountain biking as compared to road cycling (Titlestad et al., 2006 Journal of Sports Sciences, 24(2), 125-135). Â Purpose: To describe the relationship between vibration mechanics and their interaction with terrain, bicycle and rider during a race pace effort on a cross country mountain bike track. Â Methods: Participants (n=8) completed two separate laps on a cross country track using 26â€ and 29â€ wheels, at race speed. Power, cadence, speed, heart rate, and geographical position were sampled and logged every second for control purposes. Tri-axial accelerometers located at handlebar centre, lower left arm, lower left leg, seat post, lower back and medial forehead, recorded accelerations with a output rate 128 Hz to measure vibrations experienced during the whole lap and over terrain sections (uphill and downhill). Vibrations were quantified using a root mean square (RMS) and using Fourier analyses. Â Results: RMS data showed greater total accelerations for 29â€ vs 26â€ wheels (p=0.0020), and a significant interaction of terrain and accelerometer location (p<.0001). While climbing, accelerations were generally low and concentrated at low movement frequencies. While descending, however, high RMS values were seen on the bicycle (handlebar and seat post) and the parts of the body near the interface with the bicycle (left arm and left leg), while lower accelerations at the lower back and head were not significantly different than the accelerations during climbing. Â In addition, Fourier analyses showed that the accelerations occurred at a higher frequency when compared to uphill sections. Â No differences between overall power output (p=0.3062) and heart rate (p=0.8423), yet overall time was greater for 26â€ compared to 29â€ wheels (p=0.0061). Discussion: The results show that mountain bikers are subjected to large accelerations, or vibrations, particularly during downhill sections. Â These vibrations are damped before reaching the lower back and head, which requires metabolic work. Â In addition, 29 inch wheels showed a clear performance advantage, going faster for the same average power, although resulting in greater vibrations for the riders. Â Conclusion: This study demonstrates an additional non-propulsive, muscular challenge to riding during cross country mountain biking represented by a change in accelerations at the point of interface between bike-body compared to lower back and head.