Cobalt (III) Oxyhydroxide as a Pyrrole Polymerization Initiator: a Theoretical Study

In this work, the possibility of using cobalt (III) oxyhydroxide as an electropolymerization initiator for pyrrole is studied by theoretical means. A hybrid material may be yielded by this synthesis. The mathematical model has been developed and analyzed using linear stability theory and bifurcation analysis: the steady-state stability requisites, correspondent to the synthesis efficiency, were obtained. The general causes for oscillatory and monotonic instabilities have also been detected.

Steady state stability in electrical power systems considering operation limits in generators, transformers and transmission lines

Electrical power systems are exposed to several events that can cause unstable operation scenarios. This is due to improper operation of certain components. If an event occurs, the system must be designed to overcome that contingency, thus remaining in a permanent condition that must be evaluated in order to monitor and prevent a possible collapse of the system. An evaluation of steady state stability is proposed at this work based on the capacity curves of generators, transformers and transmission lines. These remarked curves provide information on the operation point of these elements, thus allowing the application of remedial actions. PowerFactory and Matlab are used to carry out the tool for monitoring the operation points after a contingency. The effectiveness of the developed tool is validated at the IEEE 39-bus power system model, where results shows that the functionalaty for different contingencies based on the operating conditions when the components of the power system are varied, cosnquently, the tool identifies cases that require actions at the operational level.

SEAMHCRD deterministic compartmental model based on clinical stages of infection for COVID-19 pandemic in Sultanate of Oman

The present novel coronavirus (COVID-19) infection has engendered a worldwide crisis on an enormous scale within a very short period. The effective solution for this pandemic is to recognize the nature and spread of the disease so that appropriate policies can be framed. Mathematical modelling is always at the forefront to understand and provide an adequate description of the transmission of any disease. In this research work, we have formulated a deterministic compartmental model (SEAMHCRD) including various stages of infection, such as Mild, Moderate, Severe and Critical to study the spreading of COVID-19 and estimated the model parameters by fitting the model with the reported data of ongoing pandemic in Oman. The steady-state, stability and final pandemic size of the model has been proved mathematically. The various transmission as well as transition parameters are estimated during the period from June 4th to July 30th, 2020. Based on the currently estimated parameters, the pandemic size is also predicted for another 100 days. Sensitivity analysis is performed to identify the key model parameters, and the parameter gamma due to contact with the symptomatic moderately infected is found to be more significant in spreading the disease. Accordingly, the corresponding basic reproduction number has also been computed using the Next Generation Matrix (NGM) method. As the value of the basic reproduction number (R0) is 0.9761 during the period from June 4th to July 30th, 2020, the disease-free equilibrium is stable. Isolation and tracing the contact of infected individuals are recommended to control the spread of disease.

Análise do Desempenho da Coordenação Entre a Proteção Contra Perda de Excitação e os Limitadores de Subexcitação e de Estabilidade em Regime Permanente

O trabalho desenvolvido propõe avaliar, através de simulações computacionais, o desempenho da proteção contra perda de excitação (ANSI 40) em geradores síncronos coordenada com o limitador de subexcitação (UEL) do regulador de tensão, observando os limites impostos pela curva de capabilidade do gerador e seu limite de estabilidade em regime permanente (do inglês Steady State Stability Limit - SSSL). Foi utilizado um modelo real de gerador síncrono aplicado no Sistema Teste Brasileiro de 9 Barras, implementados nos softwares ANAREDE e ANATEM. Utilizando estes softwares foram simulados eventos que poderiam causar a atuação da proteção contra perda de excitação. Sendo assim, foi possível observar os benefícios da coordenação da proteção 40 com o limitador de subexcitação, garantindo uma proteção mais efetiva, com melhor sensibilidade e, portanto, contribuindo com maior confiabilidade ao sistema elétrico.