Los precios del petróleo y la actividad económica en México

Estudiamos la interdependencia entre los precios del petróleo y la actividad económica, en México, usando un análisis de spillovers estáticos y dinámicos en los dominios del tiempo y de la frecuencia. Los principales hallazgos muestran, que: 1) Las relaciones entre los precios del petróleo y la actividad económica han fluctuado en el tiempo; 2) las variaciones de los precios del petróleo tienen efectos de corto plazo y sus volatilidades, efectos de largo plazo sobre la actividad económica; 3) los precios del petróleo MAYA tienen las mayores interdependencias con la actividad económica; 4) los spillovers netos más altos entre los precios del petróleo y la actividad económica ocurrieron entre abril de 2009 y junio de 2012. El estudio usa series de variaciones y volatilidades mensuales de los precios spot del petróleo MAYA, WTI y Brent y del indicador IGAE, del período de febrero de 1993 a diciembre de 2019. Abstract We study the interdependence between oil prices and economic activity in Mexico using an analysis of static and dynamic spillovers in the time and frequency domains. The main findings show that: 1) The relationships between oil prices and economic activity have fluctuated over time; 2) variations in oil prices have short-run effects and their volatilities have long-run effects on economic activity; 3) MAYA oil prices have the main interdependences with economic activity; 4) the highest net spillovers between oil prices and economic activity occurred between April 2009 and June 2012. The study uses a series of variations and monthly volatilities of the spot oil prices MAYA, WTI, and Brent, and the IGAE indicator from February 1993 to December 2019.

Time Latency-Centric Signal Processing: A Perspective of Smart Manufacturing

Smart manufacturing employs embedded systems such as CNC machine tools, programable logic controllers, automated guided vehicles, robots, digital measuring instruments, cyber-physical systems, and digital twins. These systems collectively perform high-level cognitive tasks (monitoring, understanding, deciding, and adapting) by making sense of sensor signals. When sensor signals are exchanged through the abovementioned embedded systems, a phenomenon called time latency or delay occurs. As a result, the signal at its origin (e.g., machine tools) and signal received at the receiver end (e.g., digital twin) differ. The time and frequency domain-based conventional signal processing cannot adequately address the delay-centric issues. Instead, these issues can be addressed by the delay domain, as suggested in the literature. Based on this consideration, this study first processes arbitrary signals in time, frequency, and delay domains and elucidates the significance of delay domain over time and frequency domains. Afterward, real-life signals collected while machining different materials are analyzed using frequency and delay domains to reconfirm its (the delay domain’s) significance in real-life settings. In both cases, it is found that the delay domain is more informative and reliable than the time and frequency domains when the delay is unavoidable. Moreover, the delay domain can act as a signature of a machining situation, distinguishing it (the situation) from others. Therefore, computational arrangements enabling delay domain-based signal processing must be enacted to effectively functionalize the smart manufacturing-centric embedded systems.

What Is the Spectrum?

This chapter provides a gentle introduction to the concepts of audio signals, functions, the time and frequency domains. It discusses the fundamental ideas about the spectrum in a mostly non-mathematical way. The reader is guided through the typical parameters of sound waveforms, and shown various ways to represent their spectra. Rudiments of auditory perception and psychoacoustics are also introduced, providing the basis for the rest of the volume. A provisional definition of the spectrum is put forward at the conclusion.