Open Trajectories Research Articles

Are we human? Some examples for mapping non-linear educational practices

The aim of this paper is to explore some open conditions and trajectories for thinking about models of learning facilitation in the light of non-linear understandings, typical of the posthuman thought. The posthuman framework allows for the thematization of a plurality of methods of educational intervention that decentralize that humanist logic that operates through oppositional and hierarchical models, shifting attention toward "practical provocations" that highlight the vitality of the material and the non-human. Grounding this proposal in the expert work of those scholars who are offering systematizations of this field of study, the article brings together examples of some empirical experiences to illustrate certain applications of feminist new material, posthumanist and postqualitative approaches to education.

Terms of entanglement: a posthumanist reading of Terms of Service

ABSTRACT Contemporary connected things entail ongoing relations between producers, end users, and other actors characterized by ongoing updates and production of data about and through use. These relations are currently governed by Terms of Service (ToS) and related policy documents, which are known to be mostly ignored beyond the required interaction of ticking a box to indicate consent. This seems to be a symptom of failure to design for effectively mediating ongoing relations among multiple stakeholders involving multiple forms of value generation. In this paper, we use ToS as an entrance point to explore design practices for democratic data governance. Drawing on posthuman perspectives, we make three posthuman design moves exploring entanglements, decentering, and co-performance in relation to Terms of Service. Through these explorations we begin to sketch a space for design to engage with democratic data governance through a practice of what we call revealing design that is aimed at meaningfully making visible these complex networked relations in actionable ways. This approach is meant to open alternative possible trajectories that could be explored for design to enable genuine democratic data governance.

Bundle adjustment with motion constraints for uncalibrated multi-camera systems at the ground level

Multi-camera systems for structure from motion (SfM) are widely deployed in many mapping applications. Existing solutions assume known rig calibration, synchronized frames among cameras, as well as overlapping field of views (FoVs). In this paper, we derive novel geometric constraints assuming minimal knowns about the multi-camera systems, to benefit low-cost and non-expert use cases where uncalibrated multi-camera systems with non-typical geometry setups present, i.e., no rig calibration, no overlapping FoVs. Assuming that these cameras are co-located and share the same motion of the platform, the proposed constraints utilize the parallelism and length proportionality of motion vectors of these co-located cameras and formulate them as translation constraints into the bundle adjustment (BA). The proposed constraints (called motion constraints) impose a first-order penalty to co-located cameras whose motion speeds and directions between frames do not match. With soft constraints, it can handle loosely synchronized frames (with an error within one second). The proposed constraints are integrated into the BA framework and experimented with different camera setups, i.e., on a group of casually co-located GoPro cameras with no rig calibration, and some with no overlapping views. Our results show that the constraints are extremely effective in improving the reconstruction and pose accuracy for ground motion images: in our self-collected open trajectories without loop closure, the proposed constraints are effective in correcting topographical errors (i.e., trajectory drifts) of the resulting models, and the dense point clouds achieve up to 11.34 m (86.12 %) of mean absolute error (MAE) improvement as compared to reference LiDAR point clouds; our results on KITTI-odometry and KITTI-360 datasets also show an improvement of up to 28.82 m (81.05 %) in terms of the root mean square error (RMSE) of absolute pose error (APE). We expect that the proposed constraints are significant not only as additional geometric constraints for image-based mobile mapping, but also will benefit the broader use of photogrammetry, since it empowers the possibility to harness the traditionally so-called low-quality stereo/multi-camera data (e.g., by non-photogrammetry citizen scientists) into improved 3D products.

Motion of charged particles in bright squeezed vacuum

The motion of laser-driven electrons quivers with an average energy termed pondermotive energy. We explore electron dynamics driven by bright squeezed vacuum (BSV), finding that BSV induces width oscillations, akin to electron quivering in laser light, with an equivalent ponderomotive energy. We identify closed and open trajectories of the electronic width that are associated with high harmonic generation and above-threshold ionization, respectively, similarly to trajectories of the electron position when its motion is driven by coherent light. In the case of bound electrons, the width oscillations may lead to ionization with noisy sub-cycle structure. Our results are foundational for strong-field and free-electron quantum optics, as they shed light on ionization, high harmonic generation, and nonlinear Compton scattering in BSV.

Kagome Quantum Oscillations in Graphene Superlattices.

Electronic spectra of solids subjected to a magnetic field are often discussed in terms of Landau levels and Hofstadter-butterfly-style Brown-Zak minibands manifested by magneto-oscillations in two-dimensional electron systems. Here, we present the semiclassical precursors of these quantum magneto-oscillations which appear in graphene superlattices at low magnetic field near the Lifshitz transitions and persist at elevated temperatures. These oscillations originate from Aharonov-Bohm interference of electron waves following open trajectories that belong to a kagome-shaped network of paths characteristic for Lifshitz transitions in the moire superlattice minibands of twistronic graphenes.

Perekhody Lifshitsa i uglovye diagrammy provodimosti v metallakh so slozhnymi poverkhnostyami Fermi

We consider the Lifshitz topological transitions and the corresponding changes in the galvano-magnetic properties of a metal from the point of view of the general classification of open electron trajectories arising on Fermi surfaces of arbitrary complexity in the presence of magnetic field. The construction of such a classification is the content of the Novikov problem and is based on the division of non-closed electron trajectories into topologically regular and chaotic trajectories. The description of stable topologically regular trajectories gives a basis for a complete classification of non-closed trajectories on arbitrary Fermi surfaces and is connected with special topological structures on these surfaces. Using this description, we describe here the distinctive features of possible changes in the picture of electron trajectories during the Lifshitz transitions, as well as changes in the conductivity behavior in the presence of a strong magnetic field. As it turns out, the use of such an approach makes it possible to describe not only the changes associated with stable electron trajectories, but also the most general changes of the conductivity diagram in strong magnetic fields.

Exact solution and coherent states of an asymmetric oscillator with position-dependent mass

We revisit the problem of the deformed oscillator with position-dependent mass [da Costa et al., J. Math. Phys. 62, 092101 (2021)] in the classical and quantum formalisms by introducing the effect of the mass function in both kinetic and potential energies. The resulting Hamiltonian is mapped into a Morse oscillator by means of a point canonical transformation from the usual phase space (x, p) to a deformed one (xγ, Πγ). Similar to the Morse potential, the deformed oscillator presents bound trajectories in phase space corresponding to an anharmonic oscillatory motion in classical formalism and, therefore, bound states with a discrete spectrum in quantum formalism. On the other hand, open trajectories in phase space are associated with scattering states and continuous energy spectrum. Employing the factorization method, we investigate the properties of the coherent states, such as the time evolution and their uncertainties. A fast localization, classical and quantum, is reported for the coherent states due to the asymmetrical position-dependent mass. An oscillation of the time evolution of the uncertainty relationship is also observed, whose amplitude increases as the deformation increases.

THE EXACT SOLUTIONS TO THE GRAVITATIONAL CONTRACTION IN COMOVING COORDINATE SYSTEM

The gravitational collapse of a star is a warmly discussed but still puzzling problem, which not only involves the dynamics of the gases, but also the subtle coordinate transformation. In this letter, we give some more detailed investigation on this problem, and reach the results: (I). The comoving coordinate system for the stellar system is only compatible with the zero-pressure free falling particles. (II). For the free falling dust, there are three kind of solutions respectively corresponding to the oscillating, the critical and the open trajectories. The solution of Oppenheimer and Snyder is the critical case. (III). All solutions are exactly derived. There is a new kind singularity in the solution, but its origin is unclear.

Magnetometamaterials: Metamaterials with Tunable Magnetic Matter Conductivity

The transport of tiny particles is of great interest in the field of lab-on-a-chip. Here, by drawing inspiration from electric materials, we introduce magnetometamaterials, which, as opposed to electrons, transport magnetic particles (i.e., matter). The proposed metamaterial is composed of lithographically patterned disk-shaped micromagnets arranged in rows forming linear magnetic tracks on a silicon substrate. It is shown that by applying an external rotating magnetic field with the right frequency, the particles move along the magnetic tracks. The magnetic matter transport rate (i.e., magnetic matter conductivity) is tuned by adjusting the external magnetic field. We show that the particle transport is similar to the classical electron transport through a periodic lattice. At low frequencies, similar to the electrons at low temperatures, the particles move in closed loops around single magnets, resulting in an insulating regime. At higher frequencies, similar to the electrons at higher temperatures, some particles show the same behavior (i.e., move in closed loops); however, some others move along the magnetic tracks (i.e., demonstrate open trajectories). This behavior resembles a magnetic matter semiconductor. At even higher frequencies, all the particles show open trajectories along the magnetic tracks, and the device resembles a magnetic matter conductor. We define the operational ranges, both theoretically and experimentally, for both one- and two-dimensional magnetometamaterials. We show that, in an appropriate vertical bias field, the two-dimensional magnetometamaterials can transport the particles in arbitrary paths. The proposed metamaterial in this work can be used in designing circuits for transporting particles with crucial applications in biomedical engineering.

The new institutional economy: ways of renewal and social inequalities

Purpose of the research – to determine the ways of renewal and social inequalities in the new institutional economy.Methodology – historical and causal analysis.Originality / value. The articulation of external compulsion with internal productive and social dynamics is a common explanation for the existence of open and diverse trajectories of occurrence. Here we show that they are also driven by the sectoral dynamics, the internal transformation of social relations, and the institutional dynamics that accompany the profound structural changes that "emerging" economies undergo.Findings – systematization of scientists ' opinions on the formation of scientifi c views on the institutional economy and institutions.

Particle interactions with permeable drops in shear flow

Motivated by particle removal from suspension by agglomeration with drops, the behavior of a spherical solid particle as it approaches a spherical drop covered with a rigid, permeable film is examined numerically. The particle and drop are in an external shear flow where viscous forces dominate. First, we revisit the classical problem of a particle interacting with a non-permeable drop, which includes closed orbits and open trajectories, but no collisional trajectories (without attractive forces present). Next, permeability is introduced, which modifies the two-sphere mobility functions for the system. For permeable drops, four types of trajectories are found, including infinity to drop (collision), infinity to infinity (miss), finite drop-to-drop, and closed-orbit trajectories. The collision efficiency as a function of the particle/drop size ratio and film permeability is then calculated. The efficiency dramatically increases with permeability, and it is maximum when the particle and drop are of nearly equal size.

Covid-19 as a Generator of Pending Narratives: Developing an Empirical Tool to Analyze Narrative Practices in Constructing Futures

The article describes the basic elements of the pending narrative and develops them into a tool of qualitative analysis by taking examples from Covid-19-related reports, opinions and editorials in the news. The pending narrative is a powerful story form, persuading the responsible actors in public to take action by stirring up compelling passion for a specific goal. It has a cogency that comes from the threat that if we do not act in the right way now, the continuity of life will be jeopardized. Crises are fertile breeding grounds for pending narratives, and the arrival of the Covid-19 virus is an expressive example of a situation threatening the continuity of human life around the globe. These circumstances feed on the emergence of pending narratives, which translate the unknown, uncertain and frightening future from open, multiple and unpredictable trajectories into more closed, predictable and controllable pathways. In the development of the pending narrative into a tool of qualitative analysis, the article takes influences from narratology, Bamberg’s theory on positioning analysis, Greimas’ narrative semiotics and critical discourse analysis. It proposes that in the analysis of pending narratives we benefit from the separation of three levels. On the first level, pending narratives highlight disorder and the menacing trajectory of the anti-subject, and outline a qualifying trajectory for the subject to overcome the threat. On the second level they persuade the responsible actors and the audience to identify with the qualifying trajectory and to take action or support it. And on the third level they articulate the kind of values, identities and moral order in aid of which the required action is taken.

Geometrizing Quantum Dynamics of a Bose-Einstein Condensate

We show that quantum dynamics of Bose-Einstein condensates in the weakly interacting regime can be geometrized by a Poincaré disk. Each point on such a disk represents a thermofield double state, the overlap between which equals the metric of this hyperbolic space. This approach leads to a unique geometric interpretation of stable and unstable modes as closed and open trajectories on the Poincaré disk, respectively. The resonant modes that follow geodesics naturally equate fundamental quantities including the time, the length, and the temperature. Our work suggests a new geometric framework to coherently control quantum systems and reverse their dynamics using SU(1,1) echoes. In the presence of perturbations breaking the SU(1,1) symmetry, SU(1,1) echoes deliver a new means to measure these perturbations such as the interactions between excited particles.

Breaking of Cubic Symmetry in Rare-Earth Dodecaborides with Dynamic Charge Stripes

The effect of symmetry lowering for the parameters of electron transport in rare-earth dodecaborides RB12 (R = Ho, Er, Tm, Lu) with fcc crystal structure at temperatures T ≤ 150 K has been discovered. It has been shown that the anisotropy of the magnetoresistance increases sharply at the transition to the disordered cage-glass phase below T* ~ 60 K. This effect is observed in magnetic and nonmagnetic rare-earth dodecaborides, including solid solutions RxLu1–xB12 with high substitutional disorder. The role of the electron phase separation (charge stripes along the 〈110〉 direction) in these metals with open trajectories on the Fermi surface is discussed.

PERFORMANCE EVALUATION OF A MOBILE MAPPING APPLICATION USING SMARTPHONES AND AUGMENTED REALITY FRAMEWORKS

Abstract. In this paper, we present a performance evaluation of our smartphone-based mobile mapping application based on an augmented reality (AR) framework in demanding outdoor environments. The implementation runs on Android and iOS devices and demonstrates the great potential of smartphone-based 3D mobile mapping. The application includes several functionalities such as device tracking, coordinate, and distance measuring as well as capturing georeferenced imagery. We evaluated our prototype system by comparing measured points from the tracked device with ground control points in an outdoor environment with four different campaigns. The campaigns consisted of open and closed-loop trajectories and different ground surfaces such as grass, concrete and gravel. Two campaigns passed a stairway in either direction. Our results show that the absolute 3D accuracy of device tracking with state-of-the-art AR framework on a standard smartphone is around 1% of the travelled distance and that the local 3D accuracy reaches sub-decimetre level.

Theory of hydrodynamic interaction of two spheres in wall-bounded shear flow

It is shown theoretically that the presence of a wall induces qualitative and quantitative changes in the hydrodynamic interaction between two particles in a shear flow. The phase portrait of particles' relative motion is rather different from the classical Batchelor and Green's theory corresponding to an unbounded shear flow. It has the same topology upon varying the distance between the particle pair and the wall and contains new, previously overlooked, regions of closed trajectories. The theory is able to explain the origin of open swapping trajectories found earlier in numerical simulations.

SCIENTIFIC THOUGHT AND ABSOLUTES

We propose a reflection on the construction of scientific knowledge and in so doing an image of this knowledge. This will allow us to develop a comparative analysis of some of the main principles underpinning the constitution of the different sciences. We will highlight the role of critical thought in science, or even “negative results,” which pose limits and hence open new trajectories. In particular, we will address a misleading point of view, based on some informal concepts taken from computer science, which dominates the biological imaginary. An “ethics of knowledge” will follow, as a critical and open perspective, capable of taking on the well-intentioned responsibility of proposing universal, though not absolute, principles of knowledge.

Novel approach for planetary gear train dimensional synthesis through kinematic mapping

The synthesis of a kinematic trajectory traversed by an output link (planet gear) and posture of a planetary gear train with noncircular gears can be divided into two phases: dimensional synthesis of the open-chain 2R mechanism (planetary carrier) and optimization of the transmission ratio of noncircular gear pairs. According to kinematic mapping theory, more than one closed coupler trajectory can be obtained by five preset poses. Simultaneous consideration of the trajectory shape, posture, and gear ratio is difficult during planetary gear train synthesis. This work therefore proposes a new method for the synthesis of planetary gear train in which different path segments in different trajectories are selected and a group of same-type 2R mechanisms is employed to pass through them in order to rebuild a new, closed trajectory. Subsequently, the transmission ratio of noncircular gear pairs can be determined using the relative angular displacement of the 2R mechanism. To improve the roundness of the pitch curves of noncircular gears, two optimization steps are implemented using a genetic algorithm without alternating the data points of the requisite open trajectories. For example, a mechanism for rice pot seedling transplanting is obtained by using the method.

The Second Boundaries of Stability Zones and the Angular Diagrams of Conductivity for Metals Having Complicated Fermi Surfaces

We consider some general aspects of dependence of magneto-conductivity on a magnetic field in metals having complicated Fermi surfaces. As it is well known, a nontrivial behavior of conductivity in metals in strong magnetic fields is connected usually with appearance of non-closed quasiclassical electron trajectories on the Fermi surface in a magnetic field. The structure of the electron trajectories depends strongly on the direction of the magnetic field and usually the greatest interest is caused by open trajectories that are stable to small rotations of the direction of $\, {\bf B} $. The geometry of the corresponding Stability Zones on the angular diagram in the space of directions of $\, {\bf B} \, $ represents a very important characteristic of the electron spectrum in a metal linking the parameters of the spectrum to the experimental data. Here we will consider some very general features inherent in the angular diagrams of metals with Fermi surfaces of the most arbitrary form. In particular, we will show here that any Stability Zone actually has a second boundary, restricting a larger region with a certain behavior of conductivity. Besides that, we shall discuss here general questions of complexity of the angular diagrams for the conductivity and propose a theoretical scheme for dividing the angular diagrams into "simple" and "complex" diagrams. The proposed scheme will in fact also be closely related to behavior of the Hall conductivity in a metal in strong magnetic fields. In conclusion, we will also discuss the relationship of the questions under consideration to the general features of an (abstract) angular diagram describing the behavior of quasiclassical electron trajectories at all energy levels in the conduction band.

Bimodal pair f-KdV dynamics in star-forming clouds

A theoretical formalism for investigating the bimodal conjugational mode dynamics of hybrid source, dictated by a unique pair of forced Korteweg-de Vries (f-KdV) equations in a complex turbo-magnetized star-forming cloud, is reported. It uses a standard multi-scale analysis executed over the cloud-governing equations in a closure form to derive the conjugated pair f-KdV system. We numerically see the structural features of two distinctive classes of eigenmode patterns stemming from the conjoint gravito-electrostatic interplay. The electrostatic compressive monotonic aperiodic shock-like patterns and gravitational compressive non-monotonic oscillatory shock-like structures are excitable. It is specifically revealed that the constitutive grain-charge (grain-mass) acts as electrostatic stabilizer (gravitational destabilizer) against the global cloud collapse dynamics. The basic features of the nonlinear coherent structures are confirmed in systematic phase-plane landscapes, indicating electrostatic irregular non-homoclinic open trajectories and gravitational atypical non-chaotic homoclinic fixed-point attractors. The relevance in the real astro-cosmic scenarios of the early phases of structure formation via wave-driven fluid-accretive transport processes is summarily emphasized.