Arbitrary Transition Research Articles

Arbitrary sensitive transitions in recurrent neural networks

An Excitable Network Attractor (ENA) is a forward-invariant set in phase space that can be used to explain input-driven behaviour of Recurrent Neural Networks (RNNs) trained on tasks involving switching between a discrete set of states. An ENA is composed of two or more attractors and excitable connections that allow transitions from one attractor to another under some input perturbation. The smallest such perturbation that makes a connection between two attractors is called the excitability threshold associated with that connection. The excitability threshold provides a measure of sensitivity of the connection to input perturbations. Errors in performance of such trained RNNs can be related to errors in transitions around the associated ENA. Previous work has demonstrated that ENAs of arbitrary sensitivity and structure can be realised in a RNN by suitable choice of connection weights and nonlinear activation function. In this paper we show that ENAs of arbitrary sensitivity and structure can be realised even using a suitable fixed nonlinear activation function, i.e. by suitable choice of weights only. We show that there is a choice of weights such that the probability of erroneous transitions is very small.

Sol-gel transition effect based on konjac glucomannan thermosensitive hydrogel for photo-assisted uranium extraction

Exploiting the intelligent photocatalysts capable of phase separation provides a promising solution to the removal of uranium, which is expected to solve the difficulty in separation and the poor selectivity of traditional photocatalysts in carbonate-containing uranium wastewater. In this paper, the γ-FeOOH/konjac glucomannan grafted with phenolic hydroxyl groups/poly-N-isopropylacrylamide (γ-FeOOH/KGM(Ga)/PNIPAM) thermosensitive hydrogel is proposed as the photocatalysts for extracting uranium from carbonate-containing uranium wastewater. The dynamic phase transformation is demonstrated to confirm the arbitrary transition of γ-FeOOH/KGM(Ga)/PNIPAM thermosensitive hydrogel from a dispersed state with a high specific surface area at low temperatures to a stable aggregated state at high temperatures. Notably, the γ-FeOOH/KGM(Ga)/PNIPAM thermosensitive hydrogel achieves a remarkably high rate of 92.3% in the removal of uranium from the wastewater containing carbonates and maintains the efficiency of uranium removal from uranium mine wastewater at over 90%. Relying on electron spin resonance and free radical capture experiment, we reveal the adsorption-reduction-nucleation-crystallization mechanism of uranium on γ-FeOOH/KGM(Ga)/PNIPAM thermosensitive hydrogel. Overall, this strategy provides a promising solution to treating uranium-contaminated wastewater, showing a massive potential in water purification.

Large Deviations beyond the Kibble-Zurek Mechanism.

The Kibble-Zurek mechanism (KZM) predicts that the average number of topological defects generated upon crossing a continuous or quantum phase transition obeys a universal scaling law with the quench time. Fluctuations in the defect number near equilibrium are approximately of Gaussian form, in agreement with the central limit theorem. Using large deviations theory, we characterize the universality of fluctuations beyond the KZM and report the exact form of the rate function in the transverse-field quantum Ising model. In addition, we characterize the scaling of large deviations in an arbitrary continuous phase transition, building on recent evidence establishing the universality of the defect number distribution.

A Survey on Radar-Based Continuous Human Activity Recognition

Radar-based human motion and activity recognition is currently a topic of great research interest, as the aging population increases and older individuals prefer an independent lifestyle. This technology has a wide range of applications, such as fall detection in assisted living, gesture recognition for human-machine interfaces, and many more. Numerous studies exist on various approaches for radar-based activity capture and classification. However, most of these employ rather artificial data, often obtained in laboratory environments, and typically collected under particular conditions. Specifically, most research so far has aimed at distinguishing a predefined set of single activities with a defined start, stop and duration. This paper aims at drawing the attention to a so far less researched issue, one that will be of vital importance for future real-world application of radar-based human activity recognition: continuous activity recognition, i.e. recognizing specific activities in a stream of several sequential activities with unknown duration and arbitrary transitions between different classes of activities. A review on the current state of the art in this relatively new topic is given, followed by a discussion on future research directions.

Revisiting boundary-driven non-equilibrium Markov dynamics in arbitrary potentials via supersymmetric quantum mechanics and via explicit large deviations at various levels

For boundary-driven non-equilibrium Markov models of non-interacting particles in one dimension, either in continuous space with the Fokker–Planck dynamics involving an arbitrary force F(x) and an arbitrary diffusion coefficient D(x), or in discrete space with the Markov jump dynamics involving arbitrary nearest-neighbor transition rates , the Markov generator can be transformed via an appropriate similarity transformation into a quantum supersymmetric Hamiltonian with many remarkable properties. We first describe how the mapping from the boundary-driven non-equilibrium dynamics towards some dual equilibrium dynamics (see Tailleur et al 2008 J. Phys. A: Math. Theor. 41 505001) can be reinterpreted via the two corresponding quantum Hamiltonians that are supersymmetric partners of each other, with the same energy spectra. We describe the consequences for the spectral decomposition of the boundary-driven dynamics, and we give explicit expressions for the Kemeny times needed to converge towards the non-equilibrium steady states. We then focus on the large deviations at various levels for empirical time-averaged observables over a large time-window T. We start with the always explicit Level 2.5 concerning the joint distribution of the empirical density and of the empirical flows before considering the contractions towards lower levels. In particular, the rate function for the empirical current alone can be explicitly computed via the contraction from the Level 2.5 using the properties of the associated quantum supersymmetric Hamiltonians.

A Fairness-Enhanced Intelligent MAC Scheme Using Q-Learning-Based Bidirectional Backoff for Distributed Vehicular Communication Networks

With the increasing attention to front-edge vehicular communication applications, distributed resource allocation is beneficial to the direct communications between vehicle nodes. However, in highly dynamic distributed vehicular networks, quality of service (QoS) of the systems would degrade dramatically because of serious packet collisions in the absence of sufficient link knowledge. Focusing on the fairness optimization, a Q-learning-based collision avoidance (QCA) scheme, which is characterized by an ingenious bidirectional backoff reward model R <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">QCA</inf> corresponding to arbitrary backoff stage transitions, has been proposed in an intelligent distributed media access control protocol. In QCA, an intelligent bidirectional backoff agent based on the Markov decision process model can actively motivate each vehicle agent to update itself toward an optimal backoff sub-intervel BSI <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">opt</inf> through either positive or negative bidirectional transition individually, resulting in the distinct fair communication with a proper balance of the resource allocation. According to the reinforcement learning theory, the problem of goodness evaluation on the backoff stage self-selection policy is equal to the problem of maximizing Q function of the vehicle in the current environment. The final decision on BSI <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">opt</inf> related to an optimal contention window range was solved through maximizing the Q value or <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$Q_{\max}$</tex> . The ε-qreedy algorithm was used to keep a reasonable convergence of the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$Q_{\max}$</tex> solution. For the fairness evaluation of QCA, four kinds of dynamic impacts on the vehicular networks were investigated: mobility, density, payload size, and data rate with a network simulator NS2. Consequently, QCA can achieve fair communication efficiently and robustly, with advantages of superior Jain's fairness index, relatively high packet delivery ratio, and low time delay.

Calculation and discussion of the distribution of double magnetic ions in the lattice site: The perovskite structure with d3 -d5 superexchange interaction

In this paper, for the d3-d5 superexchange perovskite system, the distribution of double magnetic ions in the B-site is quantitatively calculated using molecular field theory. The model we established, which applies to RFe1−pCrpO3, goes one step further than the former anti-site defect one. Calculations have revealed that the distribution of Fe and Cr ions in many previous studies of Fe–Cr perovskite does not always conform to the uniform distribution. Instead, they exhibit an effect that aviods the Fe–Fe or Cr–Cr clustering. This work settles previous disputes regarding the phase transition temperature range of double perovskites and explains why the phase transition temperature shifts with the same given doping proportion. It furnishes theoretical guidance for the design of functional materials with arbitrary phase transition temperatures.

A Real-Time Self-Adaptive Thermal Metasurface.

Emerging metamaterials have served as an efficient strategy for the realization of unconventional heat control and management using structural thermal properties, and many functional thermal metadevices have been investigated. However, thermal functions are usually fixed or limited in the switching range. Thus far, real-time thermal regulation is elusive for thermal metamaterials because of deterministic artificial metastructures and uncontrollable phase transitions, coupled with the absence of dynamic adaptability. Here, a self-adaptive metasurface platform to implement programmable thermal functions via the automatic evolution of thermoelectric heat sources and real-time control of the driven voltage is reported. The proof-of-concept smart platform experimentally demonstrates arbitrary switching between elaborate thermal patterns consolidated into an active thermoelectric element matrix. Further, thermal pixels and feedback control systems are integrated into printed circuit boards, resulting in self-adaptability to any thermal requirements. This study sets up a new paradigm for arbitrary transitions between exquisite thermal patterns and is expected to pave the way for real-time thermal management in a programming formation.

Laws of Large Numbers for Non-Homogeneous Markov Systems with Arbitrary Transition Probability Matrices

Laws of Large Numbers for Non-Homogeneous Markov Systems with Arbitrary Transition Probability Matrices

Exceptional points in oligomer chains

Symmetry underpins our understanding of physical law. Open systems, those in contact with their environment, can provide a platform to explore parity-time symmetry. While classical parity-time symmetric systems have received a lot of attention, especially because of the associated advances in the generation and control of light, there is much more to be discovered about their quantum counterparts. Here we provide a quantum theory which describes the non-Hermitian physics of chains of coupled modes, which has applications across optics and photonics. We elucidate the origin of the exceptional points which govern the parity-time symmetry, survey their signatures in quantum transport, study their influence for correlations, and account for long-range interactions. We also find how the locations of the exceptional points evolve as a function of the chain length and chain parity, capturing how an arbitrary oligomer chain transitions from its unbroken to broken symmetric phase. Our general results provide perspectives for the experimental detection of parity-time symmetric phases in one-dimensional arrays of quantum objects, with consequences for light transport and its degree of coherence.

Rooting out the weeds that bind: Disemboweling the devil after 2020

AbstractYear‐end rituals give arbitrary transitions meaning, facilitate collective mourning or sensemaking, enable closure or catharsis, or, alternatively, their refusal. Through a blend of creative fiction and feminist auto‐ethnography, this essay observes the end of 2020 with a both/and offer: a medium for processing the collective trauma of 2020, the Year of the Bindweed, and an invitation to whimsically imagine the otherwise in the insurgent thallopower of 2021, the Year of the Mushroom. As I strive to uproot its endless twists and turns through 2020, I follow the bindweed's path from Minneapolis to Mars and back as it courses through countless crises named and unnamed only to wind up back in my garden. There I find that this Convolvulus arvensis is deeply rooted in an entangled system of White supremacy, heteropatriarchy, imperialism, and capitalism, regenerating itself with no clear beginning or end to weed out or unravel. Theorizing in “ex‐centric sites” (Harrison 2016), this essay is the compost pile of my ethnographic work on anti‐feminism and right‐wing populism. Drawing allegories from the garden as another way of knowing (Jones 2000), it “centers an embodied feminist ethos” (Berry et al. 2017) in a form fugitive to the conventional modalities of academic theory‐making. [Corrections added on 25 October 2021 after first online publication: The abstract was added to the article.]

Computing Equilibria with Two-Player Zero-Sum Continuous Stochastic Games with Switching Controller

Equilibrium computation with continuous games is currently a challenging open task in artificial intelligence. In this paper, we design an iterative algorithm that finds an ε-approximate Markov perfect equilibrium with two-player zero-sum continuous stochastic games with switching controller. When the game is polynomial (i.e., utility and state transitions are polynomial functions), our algorithm converges to ε = 0 by exploiting semidefinite programming. When the game is not polynomial, the algorithm exploits polynomial approximations and converges to an ε value whose upper bound is a function of the maximum approximation error with infinity norm. To our knowledge, this is the first algorithm for equilibrium approximation with arbitrary utility and transition functions providing theoretical guarantees. The algorithm is also empirically evaluated.

High order transition elements: The xNy-element concept, Part II: Dynamics

In this article, the construction of versatile transition elements for applications in dynamics is comprehensively discussed. Based on the transfinite mapping technique, also known as Coons–Gordon interpolation, piece-wise shape functions are derived such that an arbitrary number of elements with different ansatz spaces is coupled conformingly. This is an important prerequisite to enable the use of local mesh refinement strategies for regular quadrilateral discretizations. Due to the special construction of the shape functions, there are no hanging nodes that need to be taken care of. The focus in this contribution is on dynamics, and therefore, Lagrange polynomials are taken as the basis to construct shape functions for arbitrary transition elements. As a consequence, the Kronecker-delta and partition of unity properties are recovered. These properties are crucial to diagonalize the mass matrix using standard mass lumping techniques such as row-summing and diagonal scaling. The performance of the proposed family of elements is assessed by means of several benchmark examples, where the numerical rates of convergence are determined for both consistent and lumped mass matrix formulations.

Computational limitations of affine automata and generalized affine automata

We present new results on the computational limitations of affine automata (AfAs). First, we show that using the endmarker does not increase the computational power of AfAs. Second, we show that the computation of bounded-error rational-valued AfAs can be simulated in logarithmic space. Third, we identify some logspace unary languages that are not recognized by algebraic-valued AfAs. Fourth, we show that using arbitrary real-valued transition matrices and state vectors does not increase the computational power of AfAs in the unbounded-error model. When focusing only the rational values, we obtain the same result also for bounded error. As a consequence, we show that the class of bounded-error affine languages remains the same when the AfAs are restricted to use rational numbers only.

(Custodial) spaces to grow? Adolescent development during custodial transitions

ABSTRACT Drawing on empirical data from two individual research projects, this paper extends the literature on child and youth incarceration and offers a previously unexplored analysis of experiences and transitions through institutional environments for young people. Different penal environments have different operational practices and treatment according to arbitrary age-determined constructions of childhood, youth and young adulthood, evidenced by decreasing safeguards. This article demonstrates the reduction of operative and supportive investment in those held, and the shifting perception from children that require ‘training’ to young people and young adults who are managed and whose particular needs are neglected. The arbitrary nature of transitions presents a paradox between developmental maturity as an individualistic ongoing process and arbitrary age-determined transitions. As such, it is argued that there should be a more developmental approach to caring for young people across penal environments which accounts for their ongoing maturity and complex needs.

Thermodynamic Uncertainty Relation for General Open Quantum Systems

We derive a thermodynamic uncertainty relation for general open quantum dynamics, described by a joint unitary evolution on a composite system comprising a system and an environment. By measuring the environmental state after the system-environment interaction, we bound the counting observables in the environment by the survival activity, which reduces to the dynamical activity in classical Markov processes. Remarkably, the relation derived herein holds for general open quantum systems with any counting observable and any initial state. Therefore, our relation is satisfied for classical Markov processes with arbitrary time-dependent transition rates and initial states. We apply our relation to continuous measurement and the quantum walk to find that the quantum nature of the system can enhance the precision. Moreover, we can make the lower bound arbitrarily small by employing appropriate continuous measurement.

Reliability evaluation of power systems with multi-state warm standby and multi-state performance sharing mechanism

With the increasing interconnection of the power grids, the imbalanced distribution between power generation and demand in different areas has been effectively alleviated. In practical power systems, the subsystems in different areas need to meet the load requirements of each subsystem, and the performance sharing among different subsystems is one way to increase system reliability. Moreover, each subsystem can be configured with redundancy techniques especially warm standby, which consumes less energy than hot standby and has a shorter recovery time than cold standby. Furthermore, both the generating units and the performance sharing mechanism may have more than binary states in practice. Therefore, in this paper, the reliability evaluation of power systems with multi-state warm standby and multi-state performance sharing mechanism is proposed. Arbitrary state transition time distributions are allowed, and the successful activation probabilities for warm standby generating units are also embedded in the proposed model. The multi-state decision diagram (MSDD) technique is developed for system reliability evaluation. Time-dependent reliability is presented in illustrative examples to validate the proposed model and technique.

Neutrino flavor oscillations and spin rotation in matter and electromagnetic field

We obtain a relativistically covariant wave equation for neutrinos in dense matter and electromagnetic field, which describes both flavor oscillations and neutrino spin rotation. Using this equation we construct a quasiclassical theory of these phenomena. We obtain the probabilities of arbitrary spin-flavor transitions assuming the external conditions to be constant. We demonstrate that the resonance behavior of the transition probabilities is possible only when the neutrino flavor states cannot be described as superpositions of the mass eigenstates. We discover that a resonance, which is similar to the Mikheev--Smirnov--Wolfenstein resonance, takes place for neutrinos in magnetic field due to the transition magnetic moments. This resonance gives an opportunity to determine, whether neutrinos are Dirac or Majorana particles.

Path-space moderate deviations for a class of Curie–Weiss models with dissipation

We modify the spin-flip dynamics of the Curie–Weiss model with dissipation in Dai Pra, Fischer and Regoli (2013) by considering arbitrary transition rates and we analyze the phase-portrait as well as the dynamics of moderate fluctuations for macroscopic observables. We obtain path-space moderate deviation principles via a general analytic approach based on the convergence of non-linear generators and uniqueness of viscosity solutions for associated Hamilton–Jacobi equations. The moderate asymptotics depend crucially on the phase we are considering and, moreover, their behavior may be influenced by the choice of the rates.

Reliability assessment and activation sequence optimization of non-repairable multi-state generation systems considering warm standby

Warm standby has been widely applied to power generation systems to ensure safe and reliable operation with lower energy consumption and shorter leading time compared with the case of hot standby and cold standby, respectively. Since there is a series of intermediate states between perfect functioning and complete failure for generating units, multi-state characteristics emerge in power generation systems. Considering different parameters of state transition time distributions before and after activation of standby units, as well as generating units with arbitrary state transition time distributions, this entails a need to propose a reliability evaluation technique to handle multi-state power generation systems considering warm standby with arbitrary state transition time distributions. An analytic method based on multi-state decision diagram (MSDD) is proposed in this paper for the reliability analysis of the proposed systems considering successful activation probabilities of warm standby units. The MSDD-based technique is applicable to multi-state power generation systems with arbitrary state transition time distributions for generating units. The proposed method enables the automated calculation of the system reliability and expected surplus performance. Furthermore, the optimum sequence of activating warm standby units that maximizes system reliability is formulated based on the proposed automatic reliability calculation method. Illustrative examples are provided to validate the effectiveness of the proposed technique.