Numerical study of highly dispersive optical solitons with differential group delay having quadratic-cubic law of refractive index by Laplace–Adomian decomposition

This paper carries out numerical simulations of highly dispersive optical solitons with differential group delay having quadratic-cubic law of nonlinearity. The Laplace–Adomian decomposition scheme is implemented to visualize the soliton propagation dynamics. Both bright and dark solitons are addressed. The error measure for these numerical approximations is impressively low as presented.

Ticket tariffs modelling in urban and regional public transport

Ticket tariff is an important factor influencing the demand for public transport. Among basic problematics re-garding ticket tariffs are designing new fare systems and optimization of current systems. The task of optimization is influenced by two main factors: ticket prices and the structure of the tariff. Both elements were researched in this article, based on eleven public transport organizers fare systems in Poland – metropolitan areas and cities of a different scale. The purpose of this article was to define basic tariff types used in urban and regional public transport with a presentation of their function models. Ticket tariffs split into two main groups: flat and differen-tial. Differential group of tariffs covers: distance (usually are encountered fares based on a number of kilometres or stops travelled), quality (e.g. different fares on basic and express lines), time (minutes, hours or days of ticket validity, but also different tariff during on-peak and off-peak hours), sections (between which passenger travel on a transit route) and zones (transport network divided into areas, e.g. designated by municipalities bounda-ries) tariffs. The concept of this study was to transform as many tariffs as possible from tabular form to the math-ematical function. Five types of functions were considered for each tariff schematic: linear, power, polynomial, logarithmic and exponential. Functions and associated with them R-squared parameters were obtained as a result of regression analysis. The paper indicates that for time, distance and flat tariffs conformity (R2) was in most cases very high and above 0,90. The results indicate that the power function best describes time tariffs. In the case of distance tariffs, different kind of functions can be used: logarithmic, power or polynomial. The pro-posed function form of tariffs may speed up the process of creating new fare systems or upgrading existing ones. With general knowledge about the structure of tariffs and their function forms, it would be easier to determine the price of different kinds of tickets. New fare integration solutions could be also proposed in the future by using Big Data analysis.

La Inteligencia Intrapersonal en el aula de E/LE: una propuesta didáctica para alumnos sinohablantes

Resumen: El proceso de adquisición del español como LM de los estudiantes sinohablantes se ve dificultado por el elevado índice de variables conflictivas de índole lingüística y cultural que entran en juego. La importancia que estas variables tienen en el desarrollo de su proceso de enseñanza-aprendizaje convierte a los alumnos chinos en un grupo diferencial dentro del conjunto de aprendientes de E/LE. Con una lengua materna tipológicamente distante del español y educados en un sistema educativo organizado a partir del estructuralismo y del método de gramática-traducción, estos alumnos presentan unas necesidades específicas de aprendizaje que los docentes deberán tener en cuenta si desean ayudarles a completar con éxito el proceso de adquisición lingüística. Esta unidad didáctica representa, por lo tanto, un intento de llevar al aula un modelo de intervención pedagógica que atienda dichas necesidades basándose en el trabajo sobre las variables afectivas autorreferenciales como la autoestima y la motivación personal. Palabras clave: estudiante sinohablante, inteligencia intrapersonal, choque cultural, método comunicativo. Intrapersonal intelligence in the classroom of Spanish as a Foreign Language: a didactic proposal for Chinese students Abstract: The acquisition process of Spanish as a target language for Chinese students is hindered by the variety and complexity of linguistic and cultural issues which take place throughout the teaching-learning process. The significance of these issues reveals Chinese students as a differential group among their fellow students. Given the fact that their mother tongue is typologically distant from Spanish and them having been educated in a structuralist and grammar-translation-based educational system, their teachers will have to carefully take into account their learning special needs if they are willing to assist them for them to successfully achieve their language acquisition process. Therefore, the purpose of this didactic unit is to introduce in the classroom a pedagogic approach as a guideline to meet the mentioned needs. It is based on detecting and identifying their own emotions such as self-esteem and personal motivation. Key words: Chinese student, intrapersonal intelligence, cultural shock, communicative approach.

Group-Birefringence-Dispersion Measurements for Polarization-Maintaining Fibers Using a Kerr Phase-Interrogator

A method which utilizes a Kerr phase-interrogator to measure the group birefringence dispersion (GBD) of a polarization-maintaining fiber (PMF) is systematically studied in this paper. The differential group delay of two sinusoidally modulated optical signals (SMOSs) polarized along the principal axes of the PMF is measured by a Kerr phase-interrogator, which leads to the group birefringence of the PMF. As the laser wavelength of the SMOSs varies, the group birefringence as a function of the laser wavelength is obtained, and the GBD is calculated as the derivative of the group birefringence with respect to the laser wavelength. The proposed method is experimentally demonstrated by characterizations of a Panda PMF with high GBD and an elliptical core PMF with low GBD, and its performance is analyzed. The proposed method eliminates the impact of the laser coherent length and allows for characterizing the GBD of PMFs that are tens of kilometers long.

Impact of Wind Gust on High-Speed Characteristics of Polarization Mode Dispersion in Optical Power Ground Wire Cables

Polarization mode dispersion is recognized as a key factor limiting optical transmission systems, particularly those fiber links that run at bit rates beyond 10 Gbps. In-line test and characterization of polarization mode dispersion are thus of critical importance to evaluate the quality of installed optical fibers that are in use for high-speed signal traffics. However, polarization-based effects in optical fibers are stochastic and quite sensitive to a range of environmental changes, including optical cable movements. This, in turn, gives rise to undesired variations in light polarization that adversely impair the quality of the signal transmission in the link. In this work, we elaborate on experimental testing and theoretical analysis to asses changes of polarization mode dispersion in optical fibers that are caused by environmental variations, here wind gusts in particular. The study was performed on commercially harnessed optical fibers installed within optical power ground wire cables, taking into account different weather conditions. More specifically, we showed that changes caused by wind gusts significantly influence the differential group delay and the principal state of polarization in those optical fibers. For this, we experimentally measured a number of parameters to characterize light polarization properties. Measurements were carried out on C-band operated fiber-optic link formed by 111-km-long power ground wire cables and 88 spectral channels, with a test time step of 1 min during 12 consecutive days. Variations in differential group delay allowed for sensitive testing of environmental changes with measured maxims up to 10 ps under the worst wind conditions. Moreover, measured parameters were used in a numerical model to assess the quality of transmitted high-bit-rate optical signals as a function of wind conditions. The analysis revealed a negligible impact of wind on a 10 Gbps transmission, while substantial influence was noticed for higher bit rates up to 100 Gbps. These results show promises for efficient sensing of environmental changes and subsequent monitoring of the quality of recently used fiber-optic link infrastructures.