Equilibrium considerations of the updated Lagrangian formulation of beam-columns with natural concepts

Bathe and co-workers'^1,2 updated Lagrangian formulation is reviewed for a two-dimensional beam-column element. From this review a physical interpretation and properties are derived for the matrices of the method. A variant of Argyris and co-workers'^4,5 natural concept is introduced in the updated Lagrangian formulation, and a new method to derive element matrices arises. A detailed derivation of the matrices of the twodimensional beam-column element is presented to clarify further the UL formulations. Explicit expressions for these matrices, computed with the use of symbolic manipulation,¹⁷ are also presented to illustrate the concepts discussed. Finally, numerical results are shown to compare and evaluate different methods and matrices.     

Radiant and convective heat transfer for flow of a transparent gas in a short tube with sinusoidal wall heat flux

The present analysis accounts for combined convective and radiant heat transfer to a fluid flowing in a short tube with prescribed wall heat flux. The heat flux distribution used was of sine shape with maximum at the middle of the tube. This solution is known to represent the axial power variation in a nuclear reactor core. The tube wall and gas bulk temperatures were obtained by successive substitutions for the wall and gas energy balance equations. The integrals were approximated by Sympson's rule and initial guesses for the iterative process were based upon limiting cases for pure radiation and pure convection. The results of the combined solution compared with the pure radiation approach show a decrease of 30 percent for the maximum wall temperature using black surface ($\text{ε=1}$). For this same situation, the increase in the gas temperature along the tube shows a reduction of 58 percent when compared to the pure convection solution.     

Social skills of and social environments produced by different Holland types: A social perspective on person€nvironment fit models.

Acritical aspect of the environment in person–environment models is the nature and density of the social interactions of the members who populate the environment. Because social types solve problems through social mechanisms, it was hypothesized that they would have greatest skills in social coping and that the further the Euclidean distance (in Holland's hexagon) from social, the lower the skill level would be in these social skills. It was also hypothesized that there would be no differences among Holland types in skill level for problem-focused social skills. On the basis of an assessment of vocational interests and self-reported social skills of 134 undergraduates, these hypotheses were corroborated. Chemistry laboratory groups were qualitatively studied to describe the social interaction environment of persons with relative deficits in the social-coping skills. These chemists interacted often, enjoyed and benefited from the interactions, but constrained their social interactions to minimize the dependence on social-coping social skills. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Adding a temporal dimension to a logic system

We introduce a methodology whereby an arbitrary logic system L can be enriched with temporal features to create a new system T(L). The new system is constructed by combining L with a pure propositional temporal logic T (such as linear temporal logic with Since and Until) in a special way. We refer to this method as adding a temporal dimension to L or just temporalising L. We show that the logic system T(L) preserves several properties of the original temporal logic like soundness, completeness, decidability, conservativeness and separation over linear flows of time. We then focus on the temporalisation of first-order logic, and a comparison is make with other first-order approaches to the handling of time.     

Homogeneity analysis of square meter-sized electrodes for PEM electrolysis and PEM fuel cells

Electrodes for polymer electrolyte membrane electrolyzers and fuel cells are manufactured by coating a catalyst dispersion, consisting of precious metal, ionomer and solvents, onto a substrate that is subsequently dried. One target of current research is to produce square meter-sized electrodes, but so far the homogeneity that can be achieved in this scaling is unclear. To quantify the achievable homogeneity of an electrode, manufactured by means of slot die coating in a roll-to-roll pilot plant, this study focuses first on the selection of an appropriate substrate by investigating thickness, basis weight and surface free energy distribution at the square meter scale. Afterward, a dispersion is coated on the selected substrate, dried and investigated with respect to thickness and basis weight distribution. Among the investigated substrates, Kapton has the smallest scatter in terms of thickness and basis weight. The subsequent coating results in a precious metal loading of 1.10 mg cm\(^{-2}\), with a scattering of 5.5% that can be further reduced to 4.5% when edge effects can be prevented. These results are now available for further research in which it is necessary to investigate whether or not these fluctuations affect the achievable electrochemical efficiencies of electrodes.     

Syntheses and Characterization of Zinc Oxide Nanoparticles on Graphene Sheets: Adsorption-Reaction In Situ DRIFTS of Methane and CO<Subscript>2</Subscript>

Zinc oxide and graphene support as catalyst were synthesized and characterized using different techniques. Results showed that graphene presented thermal stability, and maintained its structure under heat treatment at temperatures of 500 °C. TPD He experiments showed decomposition of residual compounds, releasing oxygenated compounds after functionalization of the graphene oxide. The catalyst performance was evaluated for the reaction of CH₄?+?CO₂ and O₂ by surface reaction at programmed temperature. We observed the formation of CO, H₂ and H₂O. However, TPSR and DRIFTS coupled to a mass spectrometer evidenced methane activation on ZnO/rGO-T, due to the evolution of H₂ and CO₂ traces of water and hydrocarbons, such as ethane (C₂H₆). Less sensitive but present was the signal 60, which can be assigned to the formation of acetic acid (CH₃COOH) at 300 °C.

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New closed-form expressions for SNR estimates of Nakagami fading channels by the method of moments

Method of moments has been a parameter estimation technique appropriate to calculate signal-to-noise ratio (SNR) estimates in fading channel models in which an optimal technique like maximum likelihood estimation is not mathematically tractable. In this article, the ratio of the second moment squared to the fourth moment of the received signal envelope is considered to calculate an exact expression for the SNR estimate in Nakagami-m fading channel for M-QAM and \(\theta \)-MQAM modulations as well as expressions to evaluate the variance and the mean of the estimate. The paper presents two useful contributions for SNR estimation theory on Nakagami fading. Besides the exact algebraic expression for the estimate for a generalized QAM modulation scheme, its performance is evaluated through a statistical linearization argument.     

Theoretical and Experimental Analysis of LED Lamp for Visible Light Communications

Wireless Personal Communications - Visible light communications (VLC) are an emerging technology that uses light-emitting diodes (LEDs) and photodiodes to provide high-speed communication between...     

A real-time attack defense framework for 5G network slicing

Network Slicing (NS) is a key enabler to support 5G network services on-demand. However, since NS is a result of the recent advancement in Software-Defined Networking and Network Function Virtualization, it introduces new security issues which include attacks against an NS instance within an operator network and interslice security threats. In this scenario, identifying and mitigating attacks in real-time is of paramount importance to improve security aspects. However, it is far from being straightforward. Therefore, this work proposes the FrameRTP4, a P4-based framework that aims to deliver real-time attack detection and mitigation mechanisms in 5G NS scenarios. For this, it provides a P4-based switch that implements an Service Function Chaining protocol layer, an efficient and scalable Access Control List for the detection and mitigation of known attacks, and a monitoring system aiming to reduce the overhead induced on the control channel. Furthermore, it delivers an orchestrator that aims to control all switches in order to enable lifecycle management of NS instances and P4 table rules. Besides, it also performs some autonomous tasks such as the wildcard rules generation and the detection of new threats by using machine learning algorithms. Preliminary results point to the potential benefits of FrameRTP4 to be part of a 5G NS infrastructure.     

Production,stabilisation and characterisation of silver nanoparticles coated with bioactive polymers pluronic F68, PVP and PVA

The increasing and alarming panorama of bacterial infections and associated morbidities that occur during medical and hospital procedures makes the development of technologies that aid in controlling such bacterial infections of utmost importance. Recent studies have shown that formulations with metal nanoparticles exhibit good antibacterial properties against a broad spectrum of microorganisms. Moreover, it was demonstrated that some biologically active polymeric materials, when applied in combination with chemical antimicrobial agents, enhance the therapeutic action of the latter. The research effort entertained herein aimed at the physico‐chemical characterisation of silver nanoparticles obtained by chemical reduction, stabilised by bioactive polymers polyvinyl alcohol and polyvinylpyrrolidone, and further co‐stabilised by pluronic F68. Scanning electron microscopy images of the nanoparticles produced, coated with different stabilisers, have shown that the chemical nature of the stabilisation effect promoted incorporation of pluronic in the nanoparticles and was closely related to an increase in the silver concentration in the nanoparticle samples obtained via energy‐dispersive X‐ray spectroscopy. The study described herein also shows that the nature of the stabiliser favours the interaction of pluronic F68 with samples containing silver nanoparticles.Inspec keywords: silver, nanoparticles, polymer films, coatings, nanocomposites, nanofabrication, microorganisms, biomedical materials, nanomedicine, antibacterial activity, reduction (chemical), scanning electron microscopy, X‐ray chemical analysisOther keywords: bioactive polymers pluronic F68 coated silver nanoparticles, PVP coated silver nanoparticles, PVA coated silver nanoparticles, bacterial infections, associated morbidities, medical procedures, hospital procedures, antibacterial properties, microorganisms, biologically active polymeric materials, chemical antimicrobial agents, therapeutic action, physicochemical characterisation, chemical reduction, bioactive polymers polyvinyl alcohol, polyvinylpyrrolidone, scanning electron microscopy, stabilisation effect, energy‐dispersive X‐ray spectroscopy, Ag