Dissipative dynamics of a particle in a vibrating periodic potential: Chaos and control

The dissipative chaotic dynamics of a particle subjected to a horizontally vibrating periodic potential is characterized theoretically and confirmed numerically in the case of an external chaos-controlling periodic excitation also acting on the particle. Theoretical predictions concerning the chaotic threshold in parameter space are deduced from the application of Melnikov's method that fully determine the chaos-control scenario. Also, the structure of diverse regularization regions in parameter space is explained theoretically with the aid of an energy analysis. It was found that the phase difference between the two periodic excitations involved plays a crucial role in the chaos-control scenario, with the particular feature that its optimal value depends upon the ratio between the damping coefficient and the excitation frequency. This constitutes a genuine feature of the chaos-control scenario associated with nonsteady potentials which is in contrast to the case of steady potentials. Additionally, we demonstrate the robustness of the chaos-control scenario against the presence of low-intensity Gaussian noise and reshaping of chaos-suppressing excitations

Directed ratchet transport of cold atoms and fluxons driven by biharmonic fields: A unified view

This paper discusses two retrodictions of the theory of ratchet universality which explain previous experimental results concerning directed ratchet transport of cold atoms in dissipative optical lattices in one case and of fluxons in uniform annular Josephson junctions in the other, both driven by biharmonic fields. It has to be emphasized that these retrodictions are in sharp contrast with the current standard explanation of such experimental results, and they offer optimal control of the ratchetlike motion of such entities. New experimental proposals with cold atoms and fluxons are discussed, providing additional tests for novel predictions from ratchet universality. ©2021 American Physical Societ

Impulse-induced optimum signal amplification in scale-free networks

Optimizing information transmission across a network is an essential task for controlling and manipulating generic information-processing systems. Here, we show how topological amplification effects in scale-free networks of signaling devices are optimally enhanced when the impulse transmitted by periodic external signals (time integral over two consecutive zeros) is maximum. This is demonstrated theoretically by means of a star-like network of overdamped bistable systems subjected to generic zero-mean periodic signals and confirmed numerically by simulations of scale-free networks of such systems. Our results show that the enhancer effect of increasing values of the signal''s impulse is due to a correlative increase of the energy transmitted by the periodic signals, while it is found to be resonant-like with respect to the topology-induced amplification mechanism

The influence of competitive pressure on manufacturer internal information integration

Research on competitive pressure plays an important part in understanding a firm’s behaviour in its changing environment. This paper provides an empirical contribution to the knowledge of the relationship between competitive pressure and internal information integration in this area by focusing on manufacturer internal information integration. The findings show that the degree of manufacturer internal information can be explained by the competitive strength of the largest firm in the industry. From a management perspective, the results indicate the need to regard the competitive landscape as an additional lever of manufacturer internal information sharing

Discrete breathers in dc biased Josephson-junction arrays

We propose a method to excite and detect a rotor localized mode (rotobreather) in a Josephson-junction array biased by dc currents. In our numerical studies of the dynamics we have used experimentally realizable parameters and included self-inductances. We have uncovered two families of rotobreathers. Both types are stable under thermal fluctuations and exist for a broad range of array parameters and sizes including arrays as small as a single plaquette. We suggest a single Josephson-junction plaquette as an ideal system to experimentally investigate these solutions.Comment: 5 pages, 5 figure, to appear June 1, 1999 in PR

Specific heat effects in two-dimensional shock refractions

Compressible mixtures in supersonic flows are subject to significant temperature changes via shock waves and expansions, which affect several properties of the flow. Besides the widely studied variable transport effects such as temperature-dependent viscosity and conductivity, vibrational and rotational molecular energy storage is also modified through the variation of the heat capacity cp and heat capacity ratio gamma , especially in hypersonic flows. Changes in the composition of the mixture may also modify its value through the species mass fraction Yalfa, thereby affecting the compression capacity of the flow. Canonical configurations are studied here to explore their sharply conditioned mechanical equilibrium under variations of these thermal models. In particular, effects of cp(T , Yalfa) and gamma (T , Yalfa) on the stability of shock-impinged supersonic shear and mixing layers are addressed, on condition that a shock wave is refracted. It is found that the limits defining regular structures are affected (usually broadened out) by the dependence of heat capacities with temperature. Theoretical and high-fidelity numerical simulations exhibit a good agreement in the prediction of regular shock reflections and their post-shock aerothermal properties.Work produced with the support of a 2019 Leonardo Grant for Researchers and Cultural Creators, BBVA Foundation and Project PID2019-108592RB-C41 and PID2019-108592RA-C43 (MICINN/ FEDER, UE). Numerical simulations were carried out on the MareNostrum 4 supercomputer with the Grant RES FI-2019-1-0046. The authors gratefully acknowledge Arnaud Mura, CNRS researcher at Institut PPRIME in France, for the numerical tool CREAMS.Publicad

Author Correction: Identification of minimal parameters for optimal suppression of chaos in dissipative driven systems

Correction to: Scientific Reports https://doi.org/10.1038/s41598-017-17969-9, published online 21 December 201

Combustion characteristics of hydrochar and pyrochar derived from digested sewage sludge

In this paper, hydrochars and pyrochars were produced at 260 ºC under different residence times (2 and 4 h) using anaerobic digested sewage sludge (SSL) as initial feedstock. The effect of reaction time on the fuel properties of hydrochars and pyrochars was evaluated. Moreover, the combustion kinetics of raw SSL and the derived pyrochars and hydrochars without coal blending were determined at two different air flows (20 and 90 mL/min) and compared. In the same conditions, the yield of hydrochar was significantly lower than that of pyrochar, confirming the different reaction pathways followed in each process. The results showed hydrochars have lower carbon recovery and energy yield than pyrochars, making the latter more suitable for energy purposes. The thermogravimetric combustion study showed that both thermochemical treatments increased the ignition temperature but decreased the burnout temperature, which results in higher stability during handling and storage. However, raw SSL is better for combustion than hydrochar according to the combustibility index. In addition, the kinetic study showed that the activation energy of the combustion of biochars, especially pyrochar, is lower than that of raw SSL, which is advantageous for their combustion

Evaluation of the chemical and nutritional properties of tunisian almond cultivars

The aim of this research was to evaluate for the first time protein, oil content, fatty acid profile and sugar composition for the main commercial almond cultivars in Tunisia in comparison to foreigners. Thus, fruits from twelve locals and five introduced cultivars from France, Italy and Spain were analyzed over two years. In fact, total oil content varied from 52.28% ("Blanco") to 60.95% ("Lsen Asfour") in the first year and from 47.75% ("Zahaaf") to 56.15% ("Mahsouna") in the second. However, the highest oleic acid content was noted in "Francoli" (76.2%) for both years. It was followed by "Sahnoun" (75.11%) firstly and "Abiodh" (73.02%) secondly. Likewise, the highest linoleic acid content was observed in "Porto" for both studied years (22.87% and 23.67%). The highest palmitic acid content was detected in "Porto" (7.02%) and in "Tuono" for the consecutive years. Sugars profile was quite distinctive among cultivars. The cultivar "Porto" presented the highest total sugars (5.8 g/100g DW) and sucrose contents (4.96 g/100g DW). Nevertheless, protein content doesn"t show extreme values. For both years, the local cultivar "Zahaaf" presented the highest protein content (27 g/100g DW) while introduced French cultivar "Fournat de Breznaud" presented the lowest protein content (17 g/100g DW). All the analyzed components were different significantly according to cultivar and year effects. Results evidenced that the local Tunisian cultivars are highly rich in oil and fatty acids particularly oleic and linoleic acids, confirm the almond kernel as a high nutritional dietetic source and underline the high adaptability of some introduction

Creation of a virtual environment for supporting the teaching in Physical-Chemistry (Pharmacy)

Un aspecto importante de la práctica docente en el EEES es su interés en el trabajo global del alumno a partir del cual se establece el sistema ECTS de créditos curriculares. Este enfoque requiere una revisión de la metodología docente. Es reconocido que la irrupción de las TIC en todos los sectores sociales, ha tenido una repercusión directa en el sistema educativo. En este contexto, Internet ha demostrado no sólo su importancia como canal de transmisión de contenidos sino su potencial como herramienta docente ya que incorpora interactividad, permite la personalización en la utilización de recursos, se adapta a necesidades particulares en el proceso formativo y permite combinar diferentes tipos de recursos. La aplicación de las TIC en la educación superior es cada día más palpable. Con las limitaciones que imponen los grupos numerosos de alumnos, es clara la tendencia hacia la creación de entornos virtuales como apoyo de la docencia presencial con una integración lo más completa posible en la programación didáctica. La presente comunicación analiza estas cuestiones desde la experiencia acumulada en el desarrollo de diversos recursos docentes y la creación de un entorno específico para algunos grupos de alumnos del curso primero adscritos a las enseñanzas impartidas por el Departamento de Química Física en su sección de Farmacia. El entorno virtual se propone como a) un espacio diseñado no como acumulación de páginas HTML, sino como estructurado de una forma flexible de manera que permita ser actualizado por aportaciones múltiples; b) un espacio interactivo que facilite tanto los intercambios más habituales: profesor-alumnos, como los intercambios transversales entre los alumnos; c) una referencia para alojar recursos que complementen la actividad presencial y d) un lugar de integración de diversas herramientas de aplicación docente.A important issue regarding the educational practice in the EEES, is the interest in the students’ global work from which curricular ECST system has been established. This particular approach requires a revision of the methodology applied in teaching. It is well known that the Information and Communication Technologies (ICT) have been extended to all social sectors and have produced a special impact on the educational system. In this context, Internet has proved to be not only important as a channel for the transmission of contents but also as a potential educational tool since incorporates interactivity, allows a personalized use of multiple resources, is adaptable to particular needs in the formative process and allows to combine different kinds of resources. The application of ICT in the University studies is more extended every day. In spite of the limitations imposed by the existence of groups formed by a high number of students, a clear trend seems to consolidate nowadays: the creation of virtual environments supporting on-site teaching and which are integrated as much as possible in the study schedules. The present communication focuses on these general aspects in relation with the experience accumulated in the development of several educational resources and the creation of a specific virtual environment for students which enrolled in Physical- Chemistry (Pharmacy section) during the past academic years. The virtual environment developed is a) a designed space not for accumulating static HTML pages but structured for allowing to update it with periodical contributions; b) an interactive space where the usual communicative exchange between students and teacher as well as between students is facilitated; c) a reference in which to incorporate complementary resources in order to support 'on site' teaching; and d) a place to integrate different tools with application in educational matters