Generalized Gibbs Phase Rule and Multicriticality Applied to Magnetic Systems

A generalization of the original Gibbs phase rule is proposed in order to study the presence of single phases, multiphase coexistence, and multicritical phenomena in lattice spin magnetic models. The rule is based on counting the thermodynamic number of degrees of freedom, which strongly depends on the external fields needed to break the ground state degeneracy of the model. The phase diagrams of some spin Hamiltonians are analyzed according to this general phase rule, including general spin Ising and Blume–Capel models, as well as q-state Potts models. It is shown that by properly taking into account the intensive fields of the model in study, the generalized Gibbs phase rule furnishes a good description of the possible topology of the corresponding phase diagram. Although this scheme is unfortunately not able to locate the phase boundaries, it is quite useful to at least provide a good description regarding the possible presence of critical and multicritical surfaces, as well as isolated multicritical points.

Deep-learning-based recognition of multi-singularity structured light

Structured light with customized topological patterns inspires diverse classical and quantum investigations underpinned by accurate detection techniques. However, the current detection schemes are limited to vortex beams with a simple phase singularity. The precise recognition of general structured light with multiple singularities remains elusive. Here, we report deep learning (DL) framework that can unveil multi-singularity phase structures in an end-to-end manner, after feeding only two intensity patterns upon beam propagation. By outputting the phase directly, rich and intuitive information of twisted photons is unleashed. The DL toolbox can also acquire phases of Laguerre–Gaussian (LG) modes with a single singularity and other general phase objects likewise. Enabled by this DL platform, a phase-based optical secret sharing (OSS) protocol is proposed, which is based on a more general class of multi-singularity modes than conventional LG beams. The OSS protocol features strong security, wealthy state space, and convenient intensity-based measurements. This study opens new avenues for large-capacity communications, laser mode analysis, microscopy, Bose–Einstein condensates characterization, etc.

Analysis of a PWM Converter with Less Current Ripple, Wide Voltage Operation and Zero-Voltage Switching

This paper studies and implements a power converter to have less current ripple output and wide voltage input operation. A three-leg converter with different primary turns is presented on its high-voltage side to extend the input voltage range. The current doubler rectification circuit is adopted on the output side to have low current ripple capability. From the switching states of the three-leg converter, the presented circuit has two equivalent sub-circuits under different input voltage ranges (Vin = 120–270 V or 270–600 V). The general phase-shift pulse-width modulation is employed to control the presented converter so that power devices can be turned on at zero voltage in order to reduce switching loss. Compared to two-stage circuit topologies with a wide voltage input operation, the presented converter has the benefits of simple circuit structure, easy control algorithm using a general integrated circuit or digital controller, and less components. The performance of the presented circuit is confirmed and validated by an 800 W laboratory prototype.

“Amplified Spontaneous Emission” in Micro- and Nanolasers

Amplified Spontaneous Emission is ubiquitous in systems with optical gain and is responsible for many opportunities and shortcomings. Its role in the progression from the simplest form of thermal radiation (single emitter spontaneous emission) all the way to coherent radiation from inverted systems is still an open question. We critically review observations of photon bursts in micro- and nanolasers, in the perspective of currently used measurement techniques, in relation to threshold-related questions for small devices. Corresponding stochastic predictions are analyzed, and contrasted with burst absence in differential models, in light of general phase space properties. A brief discussion on perspectives is offered in the conclusions.

Evacuation and its Types – Revision of the Definition and Classification

Objective: Evacuation is a broad concept encompassing many forms of movement in the event of an emergency. Definitions of evacuation are different in many standards and publications in the field of fire safety engineering. The introduction of a unified version of the definition will allow for a precise description of this process. The diversity of its forms and types in the literature on the subject requires the introduction of an appropriate classification. This will allow for systematization of various forms of evacuation and conducting more precise research on individual types of the evacuation process. Introduction: The evacuation process takes into account the possibility of moving not only people, but also animals and property from a place of danger to a currently safe place. It is a process that does not always take place in an organized or orderly way, and its effect is to leave the place of danger by all people. The complexity of the evacuation process allows it to be divided due to various forms, ways of conducting it, or objects subject to evacuation. In the literature on the subject, many definitions of various forms of evacuation have been formed, i.e. general, phase, organized, self-evacuation, indepen- dent, rescue, primary, gradual, selective, sequential, full, preventive, partial, successful, total, successful, successful, secondary, primary, intervention, managed, directed, unmanaged, I degree, II degree, III degree, etc. Methodology: The authors reviewed the available definitions of the concept of evacuation and proposed a new definition to describe the process in more general terms. In addition, the authors conducted a review of the forms of evacuation and its classification occurring in scientific publications within the national scope. As a result of the detailed analysis, a preliminary classification of individual determinations of the evacuation process was made. Conclusions: The concept of evacuation has a much broader meaning than the current definitions of this process. The analysis shows that evacuation should be defined as a process of moving people, animals or property from a place of danger to a place currently safe. For the purposes of this article, a total of more than 25 evacuation process determinations have been identified, which have been classified into 12 categories. Progress in many areas, i.e. construction, development of transport and urban infrastructure and the occurrence of public demonstrations/events, affects the need to verify existing definitions for the needs of new conditions. The publication aims to draw attention to the need to introduce a systematic analysis of the classification of the evacuation process. Such classification will allow for the proper identification of all kinds of variables that have different effects on different forms of this process. The introduction of such a division will allow the use of appropriate measures, tools and procedures to ensure an adequate level of human safety. The carried out categorization may be the basis for identifying the risks that may occur during individual forms of evacuation. Keywords: evacuation, evacuation definition, types of evacuation, fire safety Type of article: review article

The effects of nonlinear damping on degenerate parametric amplification

This paper considers the dynamic response of a single degree of freedom system with nonlinear stiffness and nonlinear damping that is subjected to both resonant direct excitation and resonant parametric excitation, with a general phase between the two. This generalizes and expands on previous studies of nonlinear effects on parametric amplification, notably by including the effects of nonlinear damping, which is commonly observed in a large variety of systems, including micro- and nano-scale resonators. Using the method of averaging, a thorough parameter study is carried out that describes the effects of the amplitudes and relative phase of the two forms of excitation. The effects of nonlinear damping on the parametric gain are first derived. The transitions among various topological forms of the frequency response curves, which can include isolae, dual peaks, and loops, are determined, and bifurcation analyses in parameter spaces of interest are carried out. In general, these results provide a complete picture of the system response and allow one to select drive conditions of interest that avoid bistability while providing maximum amplitude gain, maximum phase sensitivity, or a flat resonant peak, in systems with nonlinear damping.

Late-glacial fluctuations of two southern Patagonia outlet glaciers revealed by high-resolution seismic surveys

Lago Argentino hosts various calving glaciers, among them the famous Perito Moreno. Whereas the onland late Pleistocene–Holocene glacial history is rather well constrained, the submerged glacier-related features were until now undisclosed. Here we present a series of high-resolution seismic profiles revealing moraine bodies associated with the late-glacial glacier dynamics and the first bathymetric map of the Brazo Rico and Brazo Sur, the two southern arms of Lago Argentino. At the eastern termination of Brazo Rico, we identified at the lake floor the submerged expression of the Puerto Bandera 3 moraine mapped onshore, which represents the oldest event (12,660 ± 70 cal yr BP oldest minimum age) recognized in this lake arm, and seven other younger events expressed by a series of terminal and recessional moraines. Along the Brazo Sur, few moraine bodies have been imaged by seismic data. Here, the youngest temporal constraint comes from the Frías moraine (ca. 6000 cal yr BP), which closes off the southern end of the Brazo Sur. At the confluence of the two arms, the Perito Moreno and the former Frías glacier merged and flowed toward east during their late-glacial maximum advance (i.e., Puerto Bandera 1 moraine). The subaqueous evidence of moraine bodies testifies to the occurrence of previously undocumented pulses of the Perito Moreno and former Frías glaciers within the general phase of late Pleistocene–Holocene regression.

The conditions of full synchronization in generalized Kuramoto models [in Polish: Warunki pełnej synchronizacji w uogólnionych modelach Kuramoto]

A modified Kuramoto model of synchronization in a finite discrete system of locally coupled oscillators is studied. The model consists of N oscillators with random natural frequencies arranged on a ring. It is shown analytically and numerically that finite-size systems may have many different synchronized stable solutions which are characterised by different values of the winding number. The lower bound for the critical coupling $k_c$ is given, as well as an algorithm for its exact calculation. It is shown that in general phase-locking does not lead to phase coherence in 1D.