Temperature chaos is a non-local effect

Temperature chaos plays a role in important effects, like for example memory and rejuvenation, in spin glasses, colloids, polymers. We numerically investigate temperature chaos in spin glasses, exploiting its recent characterization as a rare-event driven phenomenon. The peculiarities of the transformation from periodic to anti-periodic boundary conditions in spin glasses allow us to conclude that temperature chaos is non-local: no bounded region of the system causes it. We precise the statistical relationship between temperature chaos and the free-energy changes upon varying boundary conditions.Comment: 15 pages, 8 figures. Version accepted for publication in JSTA

Causes and Effects of Chaos

Most of the recent literature on chaos and nonlinear dynamics is written either for popular science magazine readers or for advanced mathematicians. This paper gives a broad introduction to this interesting and rapidly growing field at a level that is between the two. The graphical and analytical tools used in the literature are explained and demonstrated, the rudiments of the current theory are outlined and that theory is discussed in the context of several examples: an electronic circuit, a chemical reaction and a system of satellites in the solar system

Chaos in high-power high-frequency gyrotrons

Gyrotron interaction is a complex nonlinear dynamical process, which may turn chaotic in certain circumstances. The emergence of chaos renders dynamical systems unpredictable and causes bandwidth broadening of signals. Such effects would jeopardize the prospect of advanced gyrotrons in fusion. Therefore, it is important to be aware of the possibility of chaos in gyrotrons. There are three different chaos scenarios closely related to the development of high-power gyrotrons: First, the onset of chaos in electron trajectories would lead to difficulties in the design and efficient operation of depressed potential collectors, which are used for efficiency enhancement. Second, the radio-frequency signal could turn chaotic, decreasing the output power and the spectral purity of the output signal. As a result, mode conversion, transmission, and absorption efficiencies would be reduced. Third, spatio-temporal chaos in the resonator field structure can set a limit for the use of large-diameter interaction cavities and high-order TE modes (large azimuthal index) allowing higher generated power. In this thesis, the issues above are addressed with numerical modeling. It is found that chaos in electron residual energies is practically absent in the parameter region corresponding to high efficiency. Accordingly, depressed collectors are a feasible solution also in advanced high-power gyrotrons. A new method is presented for straightforward numerical solution of the one-dimensional self-consistent time-dependent gyrotron equations, and the method is generalized to two dimensions. In 1D, a chart of gyrotron oscillations is calculated. It is shown that the regions of stationary oscillations, automodulation, and chaos have a complicated topology in the plane of generalized gyrotron variables. The threshold current for chaotic oscillations exceeds typical operating currents by a factor of ten. However, reflection of the output signal may significantly lower the threshold. 2D computations indicate that stationary single-mode operation of gyrotrons would be impossible if the azimuthal index is about 46 or larger, which is rather close to the presently used values. Moreover, electron beam misalignment can lower this critical value. Above the critical value, less favorable modes suppress the operating mode.reviewe

THE IMPACT OF GLOBAL CRISIS ON ROMANIA’S ECONOMIC DEVELOPMENT

The world is passing through the most difficult economic and financial crisis inthe history, which severely affects its stability in the long term, risking an uncontrolled slideinto chaos and uncertainty. The housing market crisis emerged in the United States in July2007, due to multiple interferences generated by the globalization, has spread to otherregions, triggering the world economy into recession. The study is trying to present the maincauses and characteristics of the crisis, with special attention to its impact on Romania, whichhas witnessed a severe economic downturn in the first half of 2009, registering a sharpdecline in industrial production, construction sector, exports and also in the lending activity.To deal with high budget deficit and liquidity pressures in the short term a financingagreement with international organizations has been concluded. But, in the long term, theexternal debt burden is increasing, the sustainable development of Romania facing new risksarising from both the global crisis and the internal vulnerabilities.international financial crisis, global recession, causes and effects of the crisis, anti-crisisremedies, external debt, sustainable development.

Effects of brake pressures on stick-slip bifurcation and chaos of the vehicle brake system

Vibrations and noises induced by vehicle braking at low speeds are problems that have always blocked the development of the automotive industry, which the stick-slip vibrations of brake system are the major reason that causes the vibration and noise. Ref. [19] predicts chaotic stick-slip vibrations by introducing a torsional model. Additionally, in this article, we have established a four degree of freedom torsional braking model under pure braking, which is based on that reference. Since the chaotic stick-slip motions have been found based on a proper friction model through numerical method, from the bifurcation diagram of the relative velocity between the rotor and pad to corresponding brake pressure, we also found the dynamic characteristics of the system changing from doubling periodic bifurcation to chaos just by increasing the brake pressures. Any further numerical study showed that the doubling periodic bifurcation occurs both in stick phase and slip phase, which composed of the upper and lower bifurcation of the global bifurcation diagram. Thus, chaos and periodic motions in it can be identified by calculating Lyapunov exponents with ‘CLDYN’ method. At last, the effects of friction model parameters on bifurcation and chaos were studied, which provides important evidence theoretically showing that the decrease in braking vibrations and noises at low speed and the matching control of braking pressures

Using methods of non-linear dynamics in historical social research: application of chaos theory in the analysis of the worker's movement in pre revolutionary Russia

"Die Autoren analysieren offizielle Statistiken der Streikbewegung in Rußland während der Jahre 1895 bis 1908 mit Methoden der Chaos-Theorie und entwickeln ein Modell zur Erklärung nicht-linearer Prozesse. Der Verlauf und die Häufigkeit der Streiks werden als Selbstorganisation der Industriearbeiter interpretiert, was der herkömmlichen Meinung nach dem Dominieren äußerer Faktoren widerspricht." (Autorenreferat)"Social conflicts often contain unpredictable peaks of activities and relatively long periods of non-stable behaviour. How could we explain such a non-linear, chaotic behaviour? What is more substantial - internal factors of these effects or external causes? Sometimes historians take into account only external factors as the main causes of the historical phenomena, though they possibly play the 'trigger' role in the processes of the 'social explosives'. Such questions can be asked in the investigation of the strike movement in Russia in the end of 19th and the beginning of the 20th century. One of possible ways to answer these questions is to apply the theory of non-linear systems with dynamically stochastic behaviour (or 'chaos'), developed in the last decades. We used official statistics of industrial strikes in the Russian Empire during the years 1895-1908. Our research demonstrates the possible appearance of 'chaos' (in mathematical sense) in the system behaviour and the existence of a rather long unstable period. To describe the development of strike movement we built the quantitative model. The system of the four non-linear ordinary differential equations was constructed after using advanced mathematical procedures to analyse the time-series. This model had a good predictor feature and for defined values of the coefficients demonstrated a chaotic behaviour. The research reveals the great role of the mechanism of information transfer and the significance of internal factors in the strike movement." (author's abstract

Moving forward in circles: challenges and opportunities in modelling population cycles

Population cycling is a widespread phenomenon, observed across a multitude of taxa in both laboratory and natural conditions. Historically, the theory associated with population cycles was tightly linked to pairwise consumer–resource interactions and studied via deterministic models, but current empirical and theoretical research reveals a much richer basis for ecological cycles. Stochasticity and seasonality can modulate or create cyclic behaviour in non-intuitive ways, the high-dimensionality in ecological systems can profoundly influence cycling, and so can demographic structure and eco-evolutionary dynamics. An inclusive theory for population cycles, ranging from ecosystem-level to demographic modelling, grounded in observational or experimental data, is therefore necessary to better understand observed cyclical patterns. In turn, by gaining better insight into the drivers of population cycles, we can begin to understand the causes of cycle gain and loss, how biodiversity interacts with population cycling, and how to effectively manage wildly fluctuating populations, all of which are growing domains of ecological research

Labor Informalization and Social Problems in Indonesia in Gender Equality Study (Case Study of Layoffs as the Effect of Digitalization in Cirebon City in 2019)

As of March 31, 2019, the Cirebon City Giant Hyper market has been declared closed and does not carry out trading activities. Employees who are dominated by women are threatened with being dismissed and this creates widespread social problems in the community. As a result of these layoffs, it has led to the growth of labor informalization with the proliferation of street workers (PKL) or independent workers which will cause chaos in the arrangement of big cities, which will have an impact on social problems. This study tries to analyze the gender equality study of the Marx model with an ethnographic approach, trying to trace the causes and effects of the informalization that afflicts female workers in the city of Cirebon