Protection of Digital Telecom Exchanges Against Lightning Surges and Earth Faults

Low-power electronic devices used in digital telecom exchanges are vulnerable to surge voltages and currents primarily originating from natural lightning or due to the direct interactions between electric power and telecommunication lines, etc., causing the earth/ground potential rise, neutral potential rise, and faults in the system. The fault currents may flow directly to telecom lines or through the equipment to the customer's premises, causing adequate damage to the equipment and personnel safety. In wireline applications, analog or digital, central office, exchanges, and subscriber sides have to be protected. Decisive protection and protective methods have to be employed for proper functioning of the equipment under overvoltage/overcurrent conditions. Current investigation reports some interesting results obtained on the recently developed high-voltage high-current protection cards used in digital telecom exchanges. The performances of protection cards both for the ring wave and hybrid wave surges are evaluated and presented. The surge generators required for the investigation are developed and fabricated in house as per the relevant telecom standards.

A Method Based on Digital Image Analysis for Measuring the Strain Field of Deformed Sheet

对薄板成形应变场传统的测量方法进行了研究,指出了其不足和误差的来源,提出了数字图像分析法测量薄板成形中的应变场,对测量原理、新的测量方法对传统方法的改进,以及如何降低误差进行了介绍,指出数字图像分析法的前景,提出了改进意见。

Thermal Properties Measurement of Micro-Electromechanical System Sensors by Digital Moire Method

The thermal properties of a micro-electromechanical system sensor were analysed by a novel digital moire method. A double-layer micro-cantilever sensor (60 mu m long, 10 mu m width and 2 mu dm thick) was prepared by focused ion beam milling. A grating with frequency of 5000 lines mm- I was etched on the cantilever. The sensor was placed into a scanning electron microscope system with a high temperature device. The observation and recording of the thermal deformation of the grating were realised in real-time as the temperature rose from room temperature to 300 degrees C at intervals of 50 degrees C. Digital moire was generated by interference of the deformed grating and a digital virtual grating. The thermal properties including strain distribution of the sensor and the linear expansion coefficient of polysilicon were accurately measured by the phase-shifted moire patterns.

Fixed-lag blind equalization and sequence estimation in digital communications systems using sequential importance sampling

We present methods for fixed-lag smoothing using Sequential Importance sampling (SIS) on a discrete non-linear, non-Gaussian state space system with unknown parameters. Our particular application is in the field of digital communication systems. Each input data point is taken from a finite set of symbols. We represent transmission media as a fixed filter with a finite impulse response (FIR), hence a discrete state-space system is formed. Conventional Markov chain Monte Carlo (MCMC) techniques such as the Gibbs sampler are unsuitable for this task because they can only perform processing on a batch of data. Data arrives sequentially, so it would seem sensible to process it in this way. In addition, many communication systems are interactive, so there is a maximum level of latency that can be tolerated before a symbol is decoded. We will demonstrate this method by simulation and compare its performance to existing techniques.

GSPS photonic analogue to digital conversion system using broadband continuous wave source

An 80 GSPS photonic ADC system is demonstrated, using broadband MLL and dispersive fibre to form a continuous waveform with time-wavelength mapping, and AWG to channelise. Tests are carried out for RF signals up to 10GHz. © 2005 Optical Society of America.

Las citas de leyes y otras normas : legislación comparada y nuevo digesto jurídico argentino

Decía Tomás de Aquino que “lex non est ipsum ius, proprie loquendo, sed aliqualis ratio iuris” 1: “[…] la ley no es el mismo derecho, propiamente hablando, sino cierta racionalización del derecho”. En concordancia con esto, entre nosotros enseñaba Alberdi que “saber, pues, leyes, no es saber derecho”, dado que “las leyes no son más que la imagen imperfecta y frecuentemente desleal del derecho que vive en la armonía viva del organismo social”, del cual hay que “conocer su genio, su misión, su rol”, porque “es el alma, la vida, el espíritu de las leyes” 2. Esto lleva, según el maestro argentino, a que “en materia de leyes, no se puede hacer nada, si no se sabe el derecho”3. El derecho no es la ley, entonces, pero sin embargo la ley tiene una relación estrecha con el derecho, del cual a veces es su causa eficiente, como ocurre con las materias de mero Derecho Positivo, y otras, es una suerte de causa ejemplar, cuando refleja la justicia natural de las cosas. La causa final inmediata de toda ley, por otra parte, debe ser el derecho, y la mediata, el bien común. El hecho, entonces, de que las leyes tengan una función segunda con respecto al derecho no las vuelve menos importantes. El conocimiento de las leyes, así, no es algo ajeno al oficio del jurista, sino que es un elemento fundamental para la búsqueda de la justicia en los casos concretos...

El fundamento del poder de la ley y el problema de las normas tautológicas

Introducción: Algunos autores proporcionalistas, en la extensa e interesante discusión que mantuvieron con algunos teóricos de la ley natural durante las últimas décadas del siglo XX plantearon la objeción de que los preceptos o normas de ley natural tenían una fundamentación tautológica, es decir, que carecían de fundamentación adecuada. La objeción no era poco importante, pues si una norma es tautológica, entonces no solo no tiene fundamento racional, sino que no reúne, como se verá, las condiciones mínimas para dirigir efectivamente las acciones morales concretas de los hombres. En otras palabras, una norma fundada tautológicamente no sería verdadera norma...