Closed-form equation for natural frequencies of beams under full range of axial loads modeled with a spring-mass system

A new simple closed-form equation that accurately predicts the effect of an arbitrarily large constant axial load, residual stress or temperature shift on the natural frequencies of an uniform single-span beam, with various end conditions, is presented. Its accuracy and applicability range are studied by comparing its predictions with numerical simulations and with the approximate Galef’s and Bokaian’s formulas. The new equation may be understood as a refinement or extension of these two approximate formulas. Significant accuracy and applicability range improvements are achieved, especially near the buckling point and for large and moderate axial load. The new closed-form equation is applicable in the full range of axial load, i.e., from the buckling load to the tensioned-string limit. It also models well the beam-to-string transition region for the eight boundary conditions studied. It works remarkably well in the free-free and sliding-free cases, where it is a near-exact solution. In addition, it yields the natural frequencies of a 1-D spring-mass system that may be used to model tensioned beams, and potentially, more complex systems.Peer ReviewedPostprint (published version

Curvature of BEOL cantilevers in CMOS-MEMS processes

© 2017 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.This paper presents the curvature characterization results of released back-end-of-line 5 µm-wide cantilevers for two different 0.18-µm 1P6M complementary metal-oxide semiconductor microelectromechanical systems processes. Results from different runs and lots from each foundry are presented. The methodology and accuracy of the characterization approach, based on optical measurements of test cantilever curvature, are also discussed. Special emphasis is given to the curvature average and variability as a function of the number of stacked layers. Analythical equations for modeling the bending behavior of stacked cantilevers as a function of the tungsten (W) vias that join the metal layers are presented. In addition, the effect of various post-processing conditions and design techniques on the curvature of both single and stacked cantilevers is analyzed. In particular, surpassing certain time-dependent temperature stress conditions after release lead to curvature shifts larger than one order of magnitude. Also, the W via design was found to strongly affect the curvature of the test cantilevers.Peer ReviewedPostprint (author's final draft

Científicos asturianos hallan un nuevo método para detectar el cáncer de páncreas

Artículo periodístico de divulgación científica escrito por Marcos Palicio.Peer Reviewe

La huella de lo esotérico en la novela La sirena negra de Emilia Pardo Bazán

El espiritismo y la teosofía son, entre las doctrinas esotéricas, las de mayor implantación en la sociedad española de fin de siglo. Ambas influyeron en las manifestaciones literarias de la época, como lo prueba su amplia presencia en la prensa y la frecuencia con la que los escritores incorporan lo sobrenatural en sus obras. Emilia Pardo Bazán integra en La sirena negra, numerosos rasgos estilísticos tomados de la estética esotérica: visión de espectros, auras, vida en objetos inanimados, sueños premonitorios, trasmigración de espíritus… Su protagonista, de perfiles satánicos, está dominado por un ansia de aniquilamiento que remite al nirvana budista. Ello no significa que la autora comulgue con tales doctrinas; por el contrario la crítica ha señalado unánimemente la marcada orientación cristiana de sus últimas novelas.Amongst the esoteric doctrines both, spiritism and theosophia, are the most firmly settled in the late 19th century Spanish society. Their influence on literary production of those days is reflected by press wide diffusion as well as frequent use of supernatural subjects by writers. In La sirena negra, Emilia Pardo Bazán incorporates for stylistic purposes a great number of esoteric aesthetics features: spectra, auras, premonitory dreams, spirit transmigration and perception of life in inanimate objects. The protagonist, that shows some Satanist character types, is seduced by a desire of self-annihilation that reminds of Buddhist Nirvana. This fact does not indicate that the author shares these doctrines; on the contrary her deep Christian orientation in her late novels has been unanimously emphasized by critics

Towards Next Generation Teaching, Learning, and Context-Aware Applications for Higher Education: A Review on Blockchain, IoT, Fog and Edge Computing Enabled Smart Campuses and Universities

[Abstract] Smart campuses and smart universities make use of IT infrastructure that is similar to the one required by smart cities, which take advantage of Internet of Things (IoT) and cloud computing solutions to monitor and actuate on the multiple systems of a university. As a consequence, smart campuses and universities need to provide connectivity to IoT nodes and gateways, and deploy architectures that allow for offering not only a good communications range through the latest wireless and wired technologies, but also reduced energy consumption to maximize IoT node battery life. In addition, such architectures have to consider the use of technologies like blockchain, which are able to deliver accountability, transparency, cyber-security and redundancy to the processes and data managed by a university. This article reviews the state of the start on the application of the latest key technologies for the development of smart campuses and universities. After defining the essential characteristics of a smart campus/university, the latest communications architectures and technologies are detailed and the most relevant smart campus deployments are analyzed. Moreover, the use of blockchain in higher education applications is studied. Therefore, this article provides useful guidelines to the university planners, IoT vendors and developers that will be responsible for creating the next generation of smart campuses and universities.Xunta de Galicia; ED431C 2016-045Xunta de Galicia; ED431G/01Agencia Estatal de Investigación de España; TEC2016-75067-C4-1-

Design of a Fog Computing, Blockchain and IoT-Based Continuous Glucose Monitoring System for Crowdsourcing mHealth

[Abstract] Diabetes Mellitus, usually called only Diabetes, is a worldwide chronic metabolic disorder that is characterized by abnormal oscillations in blood sugar levels. Such levels should be monitored by diabetes patients, which traditionally have had to take blood samples by finger-pricking, at least between twice and four times a day. Finger-pricking has a number of drawbacks that can be tackled by Continuous Glucose Monitors (CGMs), which are able to determine blood sugar levels throughout the day and not only at specific time instants. In this paper, the design of an IoT CGM-based system is proposed, whose collected blood sugar sample values can be accessed remotely; thus being able to monitor patients, specifically dependent ones (e.g., children, elders, and pregnant women) and warn them in the case where a dangerous situation is detected. In order to create such a system, a fog computing system, based on distributed mobile smart phones, has been devised to collect data from the CGMs. Moreover, the use of a blockchain is proposed, to receive, validate, and store the collected data with the objective of avoiding untrusted sources and, thus, to provide a transparent and trustworthy data source of a population, which can vary in age, ethnicity, psychology, education, self-care, and/or geographic location, in a rapid, flexible, scalable, and low-cost way. These crowdsourced data can enable novel mHealth applications for diagnosis, patient monitoring, or even public health actions, which can help to advance in the control of the disease and raise global awareness on the increasing prevalence of diabetes.Xunta de Galicia; ED431C 2016-045Xunta de Galicia; ED431G/01Agencia Estatal de Investigación de España; TEC2016-75067-C4-1-

Leveraging Blockchain for Sustainability and Open Innovation: A Cyber-Resilient Approach toward EU Green Deal and UN Sustainable Development Goals

In 2015, the United Nations (UN) member states identified 17 Sustainable Development Goals (SDGs) to be fulfilled by 2030. SDGs are an urgent global call for action to provide a blueprint for shared prosperity in a sustainable world. At a European level, in December 2019, the European Green Deal was presented, a roadmap to implement the UN 2030 agenda with a commitment to a growth strategy that will turn environmental challenges into opportunities across all policy areas. To achieve these SDGs, blockchain is one of the key enabling technologies that can help to create sustainable and secure solutions, since it is able to deliver accountability, transparency, traceability, and cyber-resilience, as well as to provide a higher operational efficiency in global partnerships. This chapter overviews the potential of blockchain to face sustainability challenges by describing several relevant applications. Finally, different open challenges and recommendations are enumerated with the aim of guiding all the stakeholders committed to the development of cyber-resilient and high-impact sustainable solutions

Use Case Based Blended Teaching of IIoT Cybersecurity in the Industry 4.0 Era

[Abstract] Industry 4.0 and Industrial Internet of Things (IIoT) are paradigms that are driving current industrial revolution by connecting to the Internet industrial machinery, management tools or products so as to control and gather data about them. The problem is that many IIoT/Industry 4.0 devices have been connected to the Internet without considering the implementation of proper security measures, thus existing many examples of misconfigured or weakly protected devices. Securing such systems requires very specific skills, which, unfortunately, are not taught extensively in engineering schools. This article details how Industry 4.0 and IIoT cybersecurity can be learned through practical use cases, making use of a methodology that allows for carrying out audits to students that have no previous experience in IIoT or industrial cybersecurity. The described teaching approach is blended and has been imparted at the University of A Coruña (Spain) during the last years, even during the first semester of 2020, when the university was closed due to the COVID-19 pandemic lockdown. Such an approach is supported by online tools like Shodan, which ease the detection of vulnerable IIoT devices. The feedback results provided by the students show that they consider useful the proposed methodology, which allowed them to find that 13% of the IIoT/Industry 4.0 systems they analyzed could be accessed really easily. In addition, the obtained teaching results indicate that the established course learning outcomes are accomplished. Therefore, this article provides useful guidelines for teaching industrial cybersecurity and thus train the next generation of security researchers and developers.This work has been funded by the Xunta de Galicia (ED431G 2019/01), the Agencia Estatal de Investigación of Spain (TEC2016-75067-C4-1-R, RED2018-102668-T, PID2019-104958RB-C42) and ERDF funds of the EU (AEI/FEDER, UE)Xunta de Galicia; ED431G 2019/0