Individual Degrees Of Freedom Research Articles

Cooling of a granular gas mixture in microgravity

Granular gases are fascinating non-equilibrium systems with interesting features such as spontaneous clustering and non-Gaussian velocity distributions. Mixtures of different components represent a much more natural composition than monodisperse ensembles but attracted comparably little attention so far. We present the observation and characterization of a mixture of rod-like particles with different sizes and masses in a drop tower experiment. Kinetic energy decay rates during granular cooling and collision rates were determined and Haff’s law for homogeneous granular cooling was confirmed. Thereby, energy equipartition between the mixture components and between individual degrees of freedom is violated. Heavier particles keep a slightly higher average kinetic energy than lighter ones. Experimental results are supported by numerical simulations.

Platonic solids bouncing on a vibrating plate.

The energy transfer between bouncing particles and rigid boundaries during impacts is crucially influenced not only by restitution coefficients of the material but also by particle shapes. This is particularly important when such particles are mechanically agitated with vibrating plates. Inertial measurement units are able to measure all acceleration and rotational velocity components of an object and store these data for subsequent analysis. We employ them to measure the dynamics of cubes and icosahedra on vibrating plates to study the efficiency of energy transfer into the individual degrees of freedom (DOFs) of the excited object. The rotational DOFs turn out to be much less excited than the vertical translational motion. Most remarkably, there is only little difference between the two Platonic solids in both the absolute energies and the energy partition ratios.

Optimizing the utilization of structural resources of flight simulator motion systems

The object of the study is a six degrees-of-freedom motion system of the synergistic type of a flight simulator. The latter is the main technical means for training pilots and means of research and development of aircraft. The task of optimal utilization of its structural resources was solved, which provides an opportunity to improve the quality of motion cueing. The result is the developed method, which ensures optimal use of structural resources of motion systems of flight simulators. This is explained, first of all, by the use of the developed simplified operator for converting the movements of jacks into the movement of a motion system along individual degrees of freedom on the basis of quadratic approximation. Given this, it became possible to describe the coordinates of the centers of the axes of rotation of the motion system by cubic spline functions. Secondly, the solution of the task of estimating the structural resources of the motion system along linear degrees of freedom on the basis of the developed criterion was carried out by an effective modified method of the deformed polyhedron. This method combines the random search method in the first steps of the search and the gradient method in determining the global extremum. Thirdly, the problem of determining the dependence of the coordinates of the pitch and yaw axes along the pitch angle was stated and solved. Owing to the optimal utilization of the structural resources of motion systems, the coordinates of the axis of their rotation along pitch are as close as possible to the coordinate of the axis of the aircraft. Thus, the quality of motion cueing on the flight simulator is significantly increased and it is possible to use motion systems with shorter lengths of jacks, and therefore, to reduce the cost of their manufacture and operation

Taking into account a location of aircraft’s center of mass during motion cuing

Compared to other information sources, motion cues provide a pilot with anticipatory information about spatial position and movement of aircraft. For motion cueing a flight simulator cockpit is installed on a motion system, movement of which motion cueing. Therefore, motion system is one of the most important components of full flight simulators. The problem of effective use of constructive resources of six-degrees of freedom synergistic motion system has been solved. But the problem of improving the motion cueing remained unsolved, due to the fact that location of motion system center of rotation is significantly different from location of aircraf’s center of gravity, and motion cues differ from real, flight one. The study subject is motion cueing on flight simulators. The problem was solved on the basis of simplified operator for transformation of motion system movements along individual degrees of freedom into jack movements, cubic spline functions to describe the dependence of the centers of rotation along pitch and yaw, and optimization theory using the deformable polyhedron method. The formulated and solved problem of taking into account of location of aircraft’s center of gravity during motion cueing along pitch and yaw increases an efficiency of using of constructive resource of a six-degrees of freedom synergistic motion system, a motion cueing fidelity and training realism on flight simulator.

Fiber-based photon-pair generation: tutorial

The purpose of this tutorial paper is to present a broad overview of photon-pair generation through the spontaneous four wave mixing (SFWM) process in optical fibers. Progress in optical fiber technology means that today we have at our disposal a wide variety of types of fiber, which, together with the fact that SFWM uses two pump fields, implies a truly remarkable versatility in the resulting possible photon-pair properties. We discuss how the interplay of frequency, transverse mode, and polarization degrees of freedom—the first linked to the latter two through fiber dispersion—leads to interesting entanglement properties both in individual degrees of freedom and also permitting hybrid and hyper entanglement in combinations of degrees of freedom. This tutorial covers methods for photon-pair factorability, frequency tunability, and SFWM bandwidth control, the effect of frequency non-degenerate and counterpropagating pumps, as well as methods for characterizing photon pairs generated in optical fibers.

Monte Carlo examination of first-order phase transitions in a system with many independent order parameters: Three-dimensional Ashkin-Teller model.

A Monte Carlo (MC) computer experiment for the analysis of first-order temperature-driven phase transitions in a system with one or many independently behaving order parameters is presented using the example of the three-dimensional (3D) Ashkin-Teller model, one of the important reference systems in statistical physics showing a rich and complex phase diagram. The properties of a number of quantities, such as magnetization, three types of cumulants, the internal energy, and its histogram, are exploited. The Lee and Kosterlitz concept proposed for strong first-order phase transitions in systems with one independent order parameter is significantly expanded to obtain results with comparable error bars in reasonable computation times at an arbitrary amount of latent heat. The proposed computer MC experiment uses parallel processing and both the Metropolis and recently formulated cluster algorithms. Arbitrarily weak to strong first-order phase transitions in the phase diagram region with ferromagnetic interactions are investigated and the latent heat associated with individual degrees of freedom is carefully computed. In the discussion of results, the behavior of our 3D system between that of the mean-field and that of the 2D one is bracketed and the role of the Potts point is clarified.

Response of a High Damping Rubber Bearing to Multiaxial Excitation

Abstract A high damping rubber bearing fabricated as part of a seismic isolation system was tested at the Caltrans Seismic Response Modification Device Test Facility at the University of California, San Diego. The purpose of the test program, which consisted of 33 tests, was to assess the impact of multiaxial excitation and input rate on the response of the bearing. The test protocol consisted of unique tests, including testing the bearing in all six degrees of freedom (uncoupled and coupled) and testing the bearing dynamically to failure. This article examines the hysteretic response and resulting performance parameters of the bearing to the different tests. The most notable impacts on the bearing’s hysteretic response were the axial loading and coupling the lateral degrees of freedom, while the rotational degrees of freedom had minimal impact on the bearing’s response. The bearing’s hysteretic response to coupling input in the rotational degrees of freedom with lateral and axial degrees of freedom was consistent with the expected performance from superimposing the response to input from individual degrees of freedom. The bearing failed at almost three times the design shear strain and at a shear force over five times the shear force at the design shear strain during the dynamic test to failure.

Analysis of RC Deep Beams Considering the Shear Deformations and Bar-concrete Interaction

In this paper, reinforced concrete (RC) deep beams (DBs) have been analyzed numerically and a new approach is proposed to the nonlinear numerical modeling of such structural members. The effect of shear deformations and the interaction between reinforcing steel bar and concrete are considered in modeling and analysis. In order to consider the effect of shear deformations, the Timoshenko beam theory has been applied to formulate the analysis method. In the modeling, the RC DB is divided into several sub-elements which are composed of concrete and reinforcing steel bars. Individual degrees of freedom have been assigned to each reinforcing steel bar. Thus, each reinforcing steel bar is able to slip relative to its surrounding concrete and the bond effect is simulated by nonlinear springs. To consider the interaction between reinforcing steel bar and concrete, the concrete segment acts as a beam element, and each reinforcing steel bar acts as a truss element. The reliability of this method has been confirmed by comparing the obtained results from the numerical analysis and the results of the experimental pushover test.

Дитя во времени. Автобиографические сражения Владимира Набокова

This article is devoted to the analysis of autobiography as a form of anthropological practice of yourself. The autobiography of Vladimir Nabokov’s “Other Shores” has been investigated from this perspective in connection with his other works. The philosophical side of Nabokov’s memoirs is considered here. This made it possible to formulate the main problems of the writer’s autobiographical work: the ratio of memory and imagination when plotting, the difference between fact and event in the structure of memory, the degree of individual freedom from coercion of objective historical circumstances, the possibility of discerning the meaning of one’s own biography long before the end of physical life. As a result of the study, Nabokov’s autobiography is characterized as a struggle against time for personal immortality. In this struggle, the writer is not so much expressing as creating yourself. He takes an active position in the act of remembrance, directing memory into the mainstream of the search for the meaning of his past, starting from early childhood. A person who remembers himself gets the opportunity to break out of the linear course of time, to distinguish repetitions in the past and read them as signs of his biography. Finally, reconfiguring biographic optics allows the author to come to a point of view from which he, through ordinary objects, begins to see not only the past and the future in their mutual transition, but also eternity. Thus, the writer avoids the main threat hanging over the mortal creature – the prospect of its annihilation.

Proposing a simplified and parametric numerical shear stress-strain model for RC deep beams

In this paper, the behaviour of reinforced concrete (RC) elements has been studied and a new shear stress-strain (SS-S) model is proposed for RC deep beams. Timoshenko beam theory is applied to consider the effect of shear deformations in numerical models. To take into account, the effect of bar-concrete interaction, the deep beam is divided into several sub-elements, and individual degrees of freedom are assigned to bars, which allow them to act independently. Since SS-S model is highly sensitive to several factors, a numerical definition of RC deep beams' shear behaviour is presented after assessing the contribution of main effective parameters on RC element's shear behaviour. The mentioned model is a push curve which has three breaking points. Proposed SS-S model is composed of several mathematical equations which allows users to easily predict the shear behaviour of RC deep beams without dealing with complex and time-consuming calculations.

Proposing a simplified and parametric numerical shear stress-strain model for RC deep beams

In this paper, the behaviour of reinforced concrete (RC) elements has been studied and a new shear stress-strain (SS-S) model is proposed for RC deep beams. Timoshenko beam theory is applied to consider the effect of shear deformations in numerical models. To take into account, the effect of bar-concrete interaction, the deep beam is divided into several sub-elements, and individual degrees of freedom are assigned to bars, which allow them to act independently. Since SS-S model is highly sensitive to several factors, a numerical definition of RC deep beams' shear behaviour is presented after assessing the contribution of main effective parameters on RC element's shear behaviour. The mentioned model is a push curve which has three breaking points. Proposed SS-S model is composed of several mathematical equations which allows users to easily predict the shear behaviour of RC deep beams without dealing with complex and time-consuming calculations.

Education system of the information age in the discourse of paradigmal forecast

Based on the regularities of the first stage of lifecycle for the social system of industrial education it is predicted the status of initiation for education and perception system around the turn of the anthropocene eon. It is emphasized that the process of the new age education system set- up takes place in self-organizing mode. For this purpose, the following is assessed: 1) the state of the “spirit of the era”, that carries an personalized (information, network, knowledge, digital) society, as an example of a new type of life order for the global community; 2) worldview imperatives of eco-humanistic filling of the educational community of the planet; 3) ideological guidelines for sustainable development; 4) conceptual prerequisites for the formation of a new education type that do not correspond in any way to the transformation of the violent paradigm of education and upbringing of young people of the technocratic age; 5) the state of fundamental science as a reason that, on the basis of mastering a new classification of social labor, should generate a modernization of education content in the 21st century; 6) the content of the involved segment of senseogenesis, which gives rise to a new division of information work in order to qualitatively service new operation forces, leading to the benefits of the development of spiritual production over material. It is prognosed that the new social division of labor will form a qualitatively new nomenclature of workers in domain of national and international education. The problems of the current state of the theory of education and pedagogy are revealed, those does not have time to produce perspectives of national and international educational policies relevant to the needs of the planet’s social organism. The attention of educators focused on the inadequacy of the existing pedagogical and organizational facilities to impact on the formation of creative personality, since they only improve the conservation of the industrial education system. The planetary personality is justified as the ideal of an educated person of the 21st century and the ultimate goal of education and upbringing in the World Knowledge Society. The principle of personalization / individualization is defined as the main parameter of managing the generation of the future education system. Emphasis is placed on the benefits of an open system of education that enhances the degree of individual freedom in a globalized world. Educators and education managers are encouraged to turn to the principles of evolution, which more strongly contribute to the spread of human activity in the school. The attractiveness of the idea of self-education for the modern young generation in the virtual space of the information age is emphasized.

Event of Freedom in the Contemporary World

The article discusses the significance and comprehension of freedom in the rapidly changing contemporary world. Unprecedented degree of individual independence and personal autonomy has been achieved, but this fact does not exclude the striving and search for the ways to gain freedom. The author presents the approaches defining a free subject as an effectively acting individuality, as a personality who surveys social practices and resists the dominant discourse, as a hyper consumer. Analyzing the concept of free subject, it is possible to reveal a tendency indicating that the achievement of independence and autonomy of an individual leads to the emergence of various kinds of contradictions, which become the basis for the emergence of new forms of dependence. The feature of modern forms of dependence is that with an unprecedented degree of individual freedom, new difficulties arise in finding their own identity. The problems of personal self-discovery, individual development are still relevant. The inaccessibility of freedom is considered as the basis for its presence since the search and striving for freedom constantly requires individual efforts contributing to the revitalization of unique forms of being. Other modes of consciousness are considered in the process of researching M. Bakhtin’s doctrine on “participatory consciousness” and K.J. Wojtyla’s teaching, which presumes that the consciousness of actions is not related to the processes of cognition, but it is expressed in the opportunity to feel himself the cause of action, to experience the authorship of this type of activity. Freedom as a way of the implementation of the being is expressed in Gilles Deleuze’s concept of the “sense-event.” Thus, freedom serves as the basis for everything that may happen, starts a new series of events, develops new rules, and, at the same time, is constantly adjusted in the process of personal efforts.

Probing magneto-elastic phenomena through an effective spin-bath coupling model

A phenomenological model is constructed, that captures the effects of coupling magnetic and elastic degrees of freedom, in the presence of external, stochastic perturbations, in terms of the interaction of magnetic moments with a bath, whose individual degrees of freedom cannot be resolved and only their mesoscopic properties are relevant. In the present work, the consequences of identifying the effects of dissipation as resulting from interactions with a bath of spins are explored, in addition to elastic, degrees of freedom. The corresponding stochastic differential equations are solved numerically and the moments of the magnetization are computed. The stochastic equations implicitly define a measure on the space of spin configurations, whose moments at equal times satisfy a hierarchy of deterministic, ordinary differential equations. Closure assumptions are used to truncate the hierarchy and the same moments are computed. We focus on the advantages and problems that each approach presents, for the approach to equilibrium and, in particular, the emergence of longitudinal damping.

Evaluation of Different Modes of Haptic Guidance for Robotic Surgery

Abstract The evolution of surgery has resulted in a plethora of systems varying in their application field, size, as well as degree of autonomy. Especially systems which combine principles of so-called synergistic robotic systems and master-slave-telemanipulators are interesting concerning cooperative aspects of surgeon and robotic system. While the former provide haptic guidance information (“virtual fixtures”), the latter provide haptic feedback from position or force sensor information of the slave device. During the design of these combined systems particular attention has to be paid during the allocation of information to the haptic information channel as superimposing of haptic guidance information and haptic sensor feedback can lead to concealment of essential feedback information. This paper reports on an experimental usability evaluation of different haptic guidance modes varying in their degree of autonomy as well as degree of freedom (DOF) with respect to three surgical scenarios, namely reaching a predefined position and orientation, tracking a predefined 3D trajectory, and applying a defined force (such as during e.g. a 3D-bone milling task). The goal was to evaluate whether some DOF of haptic guidance information can be left free for force sensor information feedback. General findings indicate that haptic guidance does not have to be augmented on three DOF to improve usability. Therefore, a combination of haptic sensor information feedback and haptic guidance information divided between individual DOF seems to be a potential solution.

Hyperentanglement of Photons Emitted by a Quantum Dot.

A hyperentangled state of light represents a valuable tool capable of reducing the experimental requirements and resource overheads, and it can improve the success rate of quantum information protocols. Here, we report on demonstration of polarization and time-bin hyperentangled photon pairs emitted from a single quantum dot. We achieved this result by applying resonant and coherent excitation on a quantum dot system with marginal fine structure splitting. Our results yield fidelities to the maximally entangled state of 0.81(6) and 0.87(4) in polarization and time bin, respectively.

Free Cooling of a Granular Gas of Rodlike Particles in Microgravity.

Granular gases as dilute ensembles of particles in random motion are at the basis of elementary structure-forming processes in the Universe, involved in many industrial and natural phenomena, and also excellent models to study fundamental statistical dynamics. The essential difference to molecular gases is the energy dissipation in particle collisions. Its most striking manifestation is the so-called granular cooling, the gradual loss of mechanical energy E(t) in the absence of external excitation. We report an experimental study of homogeneous cooling of three-dimensional granular gases in microgravity. The asymptotic scaling E(t)∝t^{-2} obtained by Haff's minimal model [J. Fluid Mech. 134, 401 (1983)JFLSA70022-112010.1017/S0022112083003419] proves to be robust, despite the violation of several of its central assumptions. The shape anisotropy of the grains influences the characteristic time of energy loss quantitatively but not qualitatively. We compare kinetic energies in the individual degrees of freedom and find a slight predominance of translational motions. In addition, we observe a preferred rod alignment in the flight direction, as known from active matter or animal flocks.

Unveiling the internal entanglement structure of the Kondo singlet

We disentangle all the individual degrees of freedom in the quantum impurity problem to deconstruct the Kondo singlet, both in real and energy space, by studying the contribution of each individual free electron eigenstate. This is a problem of two spins coupled to a bath, where the bath is formed by the remaining conduction electrons. Being a mixed state, we resort to the "concurrence" to quantify entanglement. We identify "projected natural orbitals" that allow us to individualize a single-particle electronic wave function that is responsible of more than $90\%$ of the impurity screening. In the weak coupling regime, the impurity is entangled to an electron at the Fermi level, while in the strong coupling regime, the impurity counterintuitively entangles mostly with the high energy electrons and disentangles completely from the low-energy states carving a "hole" around the Fermi level. This enables one to use concurrence as a pseudo order parameter to compute the characteristic "size" of the Kondo cloud, beyond which electrons are are weakly correlated to the impurity and are dominated by the physics of the boundary.

Gothic Truth and Mimetic Practice: On the Realism of Schiller’s Geisterseher

ABSTRACTThe official reality claim of the eighteenth-century novel established itself in sharp distinction from fantastic modes of narration (ancient epics, medieval romances, religious allegories, etc.). Realist narratives following the laws of probability draw on a fictional ontology of contingency that goes back to the Aristotelian definition of the term as “possible” and “not necessary.” The pluralistic poetics of the early novel, thereby, not only participate in the programatically modern project “of a scientific scrutiny of life” (Watt) but also forms an essential part of the modern belief in the self-determined nature of the human subject. By contrast, Gothic realism gains all its attraction by depicting impossible events and actions as “real” and assumed unrealities as “possible.” Gothic novels develop an alternative ontology of contingency that actualizes the real possibility of non-being. Next to Walpole’s Castle of Otranto, I analyze Schiller’s Ghost Seer. Schiller’s contagious poetics of mimesis transforms calculable contingencies into the imponderability of sheer accidents. Moreover, it is a tale about the mystery of sociality and about the morally justifiable degree of individual freedom. Within a fictional framework of radical indeterminacy and unexpected novelty, Schiller’s tale calls for an ethics of absolute contingency. It does not content itself with taking the possible for real and the real for non-necessary; instead, its narrative environment calls for a radically situational ethics.

Directly Characterizing the Relative Strength and Momentum Dependence of Electron-Phonon Coupling Using Resonant Inelastic X-Ray Scattering

The coupling between lattice and charge degrees of freedom in condensed matter materials is ubiquitous and can often result in interesting properties and ordered phases, including conventional superconductivity, charge density wave order, and metal-insulator transitions. Angle-resolved photoemission spectroscopy and both neutron and non-resonant x-ray scattering serve as effective probes for determining the behavior of appropriate, individual degrees of freedom -- the electronic structure and lattice excitation, or phonon dispersion, respectively. However, each provides less direct information about the mutual coupling between the degrees of freedom, usual through self-energy effects, which tend to renormalize and broaden spectral features precisely where the coupling is strong, impacting ones ability to quantitively characterize the coupling. Here we demonstrate that resonant inelastic x-ray scattering, or RIXS, can be an effective tool to directly determine the relative strength and momentum dependence of the electron-phonon coupling in condensed matter systems. Using a diagrammatic approach for an 8-band model of copper oxides, we study the contributions from the lowest order diagrams to the full RIXS intensity for a realistic scattering geometry, accounting for matrix element effects in the scattering cross-section as well as the momentum dependence of the electron-phonon coupling vertex. A detailed examination of these maps offers a unique perspective into the characteristics of electron-phonon coupling, which complements both neutron and non-resonant x-ray scattering, as well as Raman and infrared conductivity.