Desarrollo de un sistema de monitoreo de temperatura para la sala de equipos de telecomunicaciones del ICE

Proyecto de Graduación (Licenciatura en Ingeniería Electrónica). Instituto Tecnológico de Costa Rica. Escuela de Ingeniería Electrónica, 2006.El Proceso de Transmisión del ICE de San Pedro cuenta con una sala de equipos de telecomunicaciones, cuyo sistema de enfriamiento (aire acondicionado y ventilas) no logra mantener una temperatura baja uniforme, lo que da como resultado un sobrecalentamiento de los equipos con los efectos negativos que esto conlleva (disminución del ciclo de vida y averías). Este problema representa a la empresa un mayor costo económico, debido que requieren de un personal técnico para la reparación y mantenimiento, tener un inventario de componentes de repuestos y el tiempo invertido en la búsqueda de averías y en su debida reparación. Por estas razones es necesario realizar un sistema de monitoreo de la temperatura de la sala para determinar las zonas que pueden perjudicar los equipos y analizar posibles soluciones. Para implementar el sistema de monitoreo se colocaron módulos con sensores de temperatura en los bastidores, en donde se encuentra ubicados los equipos de telecomunicación. Estos módulos se comunican entre sí por medio de enlaces inalámbricos infrarrojos. Una vez recolectados los datos, éstos son enviados a una computadora que se encarga de visualizar por medio de gráficos el comportamiento térmico de la sala en estudio y además guardar la información en una base de datos. También se desarrolló el software para automatizar proceso de cambiar la temperatura de acuerdo a los valores recolectados

A state of the art of sensor location, flow observability, estimation, and prediction problems in traffic networks

A state-of-the-art review of flow observability, estimation, and prediction problems in traffic networks is performed. Since mathematical optimization provides a general framework for all of them, an integrated approach is used to perform the analysis of these problems and consider them as different optimization problems whose data, variables, constraints, and objective functions are the main elements that characterize the problems proposed by different authors. For example, counted, scanned or “a priori” data are the most common data sources; conservation laws, flow nonnegativity, link capacity, flow definition, observation, flow propagation, and specific model requirements form the most common constraints; and least squares, likelihood, possible relative error, mean absolute relative error, and so forth constitute the bases for the objective functions or metrics. The high number of possible combinations of these elements justifies the existence of a wide collection of methods for analyzing static and dynamic situations

A Systematic Mapping Study on Approaches for AI-Supported Security Risk Assessment

Effective assessment of cyber risks in the increasingly dynamic threat landscape must be supported by artificial intelligence techniques due to their ability to dynamically scale and adapt. This article provides the state of the art of AI-supported security risk assessment approaches in terms of a systematic mapping study. The overall goal is to obtain an overview of security risk assessment approaches that use AI techniques to identify, estimate, and/or evaluate cyber risks. We carried out the systematic mapping study following standard processes and identified in total 33 relevant primary studies that we included in our mapping study. The results of our study show that on average, the number of papers about AI-supported security risk assessment has been increasing since 2010 with the growth rate of 133% between 2010 and 2020. The risk assessment approaches reported have mainly been used to assess cyber risks related to intrusion detection, malware detection, and industrial systems. The approaches focus mostly on identifying and/or estimating security risks, and primarily make use of Bayesian networks and neural networks as supporting AI methods/techniques.acceptedVersio

Frameworks for data-driven quality management in cyber-physical systems for manufacturing: A systematic review

Recent advances in the manufacturing industry have enabled the deployment of Cyber-Physical Systems (CPS) at scale. By utilizing advanced analytics, data from production can be analyzed and used to monitor and improve the process and product quality. Many frameworks for implementing CPS have been developed to structure the relationship between the digital and the physical worlds. However, there is no systematic review of the existing frameworks related to quality management in manufacturing CPS. Thus, our study aims at determining and comparing the existing frameworks. The systematic review yielded 38 frameworks analyzed regarding their characteristics, use of data science and Machine Learning (ML), and shortcomings and open research issues. The identified issues mainly relate to limitations in cross-industry/cross-process applicability, the use of ML, big data handling, and data security.publishedVersio

Permutation entropy analysis of the output of a laser diode under stimulated Brillouin scattering optical feedback

The chaotic output emitted by a diode laser with optical feedback has fascinated the community for decades. The external cavity delay time imparts a weak level of periodicity to the laser output (the so-called "time delay signature", TDS) that is a drawback for applications that require random optical signals. A lot of efforts have focused in suppressing the TDS either by post-processing the signal or by using alternative ways to generate random optical signals. Here, we compare the signals generated by two optical feedback setups: in the first one, the stimulated Brillouin backscattered light from a standard optical fibre is re-injected into the laser (stimulated Brillouin scattering optical feedback, SBSOF); in the second one, the light transmitted through the fibre is re-injected into the laser (conventional optical feedback, COF). We analyse the permutation entropy, a well-known measure of complexity that captures order relations between values of a time series. We find that, on average, the signal generated by the SBSOF setup has slightly lower PE than the one generated by the COF setup, except when the sampling time of the intensity signal is an exact multiple of the delay; in that case, due to TDS, the entropy of the COF signal is lower than that of the SBSOF signal. We interpret the lower entropy value of the SBSOF signal as due to oscillations at the Brillouin frequency shift. Taken together, our results show that TDS suppression can have an undesirable side effect: a decrease of the entropy of the signal.ECOS-Nord programme (N° M19P03); Consejo Nacional de Ciencia y Tecnología (465594); Institució Catalana de Recerca i Estudis Avançats (Generalitat de Catalunya); Ministerio de Ciencia, Innovación y Universidades (PGC2018-099443-B-I00)Peer ReviewedPostprint (published version

Investigation of the Dynamical Behavior of a High-Power Laser Diode Subject to Stimulated Brillouin Scattering Optical Feedback

In this work, we propose a new scheme of optical feedback using stimulated Brillouin scattering (SBS). A highpower laser diode emitting at 1450 nm stimulates Brillouin backscattering in a 4km-long optical fibre and the back-scattered light is injected back into the laser diode for optical feedback. The experimental results with RF spectrum exhibit clearly the Brillouin frequency shift at 11.46 GHz. Although the frequency shift is very large, the laser diode subject to optical feedback using SBS shows abundant dynamics. RF spectrum maps are also established with respect to the laser drive current. The results are compared with the ones for conventional optical feedback and it is clearly shown that the dynamical behaviours for both the configurations are very different. The investigation with autocorrelation functions reveals that the time-delay signature vanishes completely using the SBS feedback scheme unlike the conventional feedback one

Investigation of behavior and perception of digital library users: A cognitive style perspective

Cognitive style is an influential factor in users’ information seeking. The study presented in this paper examines how users’ cognitive styles affect their behavior and perception in digital libraries. Fifty participants took part in this study. Two dimensions of cognitive styles were considered: (a) Field Dependence/Independence; (2) Verbalizer/Imager. The results showed that Intermediate users and Verbalizers have not only more positive perception, but they also complete the tasks in effective ways. Implications for the design of personalized digital libraries are also discussed

Iliac Vein Injury Due to a Damaged Hot Shears™ Tip Cover During Robot Assisted Radical Prostatectomy

We report a rare case of vascular injury secondary to a damaged Hot Shears™ tip cover. Two 1 mm holes in the tip cover resulted in perforations in the obturator and external iliac veins during pelvic node dissection. Bleeding was controlled with bipolar coagulation and a 5 mm metal clip in the obturator and iliac vein, respectively. The rest of the procedure was completed uneventfully. Frequent integrity assessment of this accessory is necessary. Its function is important in order to carry out safe dissection in proximity to delicate structures. When injuries arise from areas not directly involved in the dissection, immediate inspection of the instruments should be mandatory

Purely infinite crossed products by endomorphisms

We study the crossed product C⁎C⁎-algebra associated to injective endomorphisms, which turns out to be equivalent to study the crossed product by the dilated automorphism. We prove that the dilation of the Bernoulli p -shift endomorphism is topologically free. As a consequence, we have a way to twist any endomorphism of a DD-absorbing C⁎C⁎-algebra into one whose dilated automorphism is essentially free and have the same K -theory map than the original one. This allows us to construct purely infinite crossed products C⁎C⁎-algebras with diverse ideal structures

Nanoscale Phase Change Memory with Graphene Ribbon Electrodes

Phase change memory (PCM) devices are known to reduce in power consumption as the bit volume and contact area of their electrodes are scaled down. Here, we demonstrate two types of low-power PCM devices with lateral graphene ribbon electrodes: one in which the graphene is patterned into narrow nanoribbons and the other where the phase change material is patterned into nanoribbons. The sharp graphene "edge" contacts enable switching with threshold voltages as low as ~3 V, low programming currents (<1 {\mu}A SET, <10 {\mu}A RESET) and ON/OFF ratios >100. Large-scale fabrication with graphene grown by chemical vapor deposition also enables the study of heterogeneous integration and that of variability for such nanomaterials and devices.Comment: submitted to Applied Physics Letter