Dynamic Bayesian smooth transition autoregressive models applied to hourly electricity load in southern Brazil

Dynamic Bayesian Smooth Transition Autoregressive (DBSTAR) models are proposed for nonlinear autoregressive time series processes as alternative to both the classical Smooth Transition Autoregressive (STAR) models of Chan and Tong (1986) and the Bayesian Simulation STAR (BSTAR) models of Lopes and Salazar (2005). Unlike those, DBSTAR models are sequential polynomial dynamic analytical models suitable for inherently non-stationary time series with non-linear characteristics such as asymmetric cycles. As they are analytical, they also avoid potential computational problems associated with BSTAR models and allow fast sequential estimation of parameters. Two types of DBSTAR models are defined here based on the method adopted to approximate the transition function of their autoregressive components, namely the Taylor and the B-splines DBSTAR models. A harmonic version of those models, that accounted for the cyclical component explicitly in a flexible yet parsimonious way, were applied to the well-known series of annual Canadian lynx trappings and showed improved fitting when compared to both the classical STAR and the BSTAR models. Another application to a long series of hourly electricity loading in southern Brazil, covering the period of the South-African Football World Cup in June 2010, illustrates the short-term forecasting accuracy of fast computing harmonic DBSTAR models that account for various characteristics such as periodic behaviour (both within-the-day and within-the-week) and average temperature

Yukawa particles in a confining potential

We study the density distribution of repulsive Yukawa particles confined by an external potential. In the weak coupling limit, we show that the mean-field theory is able to accurately account for the particle distribution. In the strong coupling limit, the correlations between the particles become important and the mean-field theory fails. For strongly correlated systems, we construct a density functional theory which provides an excellent description of the particle distribution, without any adjustable parameters.Comment: Submitte

Interaction between random heterogeneously charged surfaces in an electrolyte solution

We study, using Monte Carlo simulations, the interaction between infinite heterogeneously charged surfaces inside an electrolyte solution. The surfaces are overall neutral with quenched charged domains. An average over the quenched disorder is performed to obtain the net force. We find that the interaction between the surfaces is repulsive at short distances and is attractive for larger separations

Equation of state of charged colloidal suspensions and its dependence on the thermodynamic route

The thermodynamic properties of highly charged colloidal suspensions in contact with a salt reservoir are investigated in the framework of the Renormalized Jellium Model (RJM). It is found that the equation of state is very sensitive to the particular thermodynamic route used to obtain it. Specifically, the osmotic pressure calculated within the RJM using the contact value theorem can be very different from the pressure calculated using the Kirkwood-Buff fluctuation relations. On the other hand, Monte Carlo (MC) simulations show that both the effective pair potentials and the correlation functions are accurately predicted by the RJM. It is suggested that the lack of self-consistency in the thermodynamics of the RJM is a result of neglected electrostatic correlations between the counterions and coions

Measuring the Energy Efficiency of Evaporative Systems through a New Index - EvaCOP

Evaporative systems are probably the oldest technology for thermal comfort. However, they are still an essential technology in the food industry, environments for thermal comfort, and even for cooling data centers. Standards have been improved to compare the energy efficiency of this type of equipment. Using AHRI concepts with temperature data from the 29 most populous cities in the world, an EvaCOP index was created from temperatures that are easier to simulate than current parameters. The index parameters were tested in a laboratory located in Curitiba (Brazil). EvaCOP values of 45.58 and 25.77 W/W were found in the calculation in two different simulated equipment and compared with the compression cycle systems that in the most efficient machines is around 6.29 W/W.info:eu-repo/semantics/publishedVersio

The concept of mass – gravitic and inertial in eurhythmic physics

The concept of mass, be it gravitic or inertial, has played a major role in traditional physics. The meaning of the concept of mass and the equivalence between inertial and gravitic mass have been and are object of great polemics in the arena of scientific discussion. In the nonlinear complex inter-relational Eurhythmic Physics, the concept of mass, that has been assumed as a fundamental idea, no longer shares this attribute. In this way of looking at Nature the concept of mass loses its fundamental status being only a relational and, under certain circumstances, useful concept

Ecoenergetic Comparison of HVAC Systems in Data Centers

The topic of sustainability is of high importance today. Global efforts such as the Montreal Protocol (1987) and the Kigali Amendment (2016) are examples of joint work by countries to reduce environmental impacts and improve the level of the ozone layer, the choice of refrigerants and air conditioning systems, which is essential for this purpose. But what indicators are to be used to measure something so necessary? In this article, the types of air conditioning and GWP (Global Warming Potential) levels of equipment in the project phase were discussed, the issue of TEWI (Total Equivalent Warming Impact) that measures the direct and indirect environmental impacts of refrigeration equipment and air conditioning and a new methodology for the indicator was developed, the TEWI DC (DC is the direct application for Data Center), and using the formulas of this new adapted indicator it was demonstrated that the TEWI DC for Chicago (USA) was 2,784,102,640 kg CO2/10 years and Curitiba (Brazil) is 1,252,409,640 kg CO2/10 years. This difference in value corresponds to 222.30% higher annual emissions in Chicago than in Curitiba, showing that it is much more advantageous to install a Data Center in Curitiba than in Chicago in terms of environmental impact. The TEWI indicator provides a more holistic view, helping to combine energy and emissions into the same indicator.info:eu-repo/semantics/publishedVersio

Evaluation of the heat and energy performance of a datacenter by a new efficiency index: Energy Usage Effectiveness Design - EUED

Data Centers are growing steadily worldwide and they are expected to continue on growing up to 53% in 2020. Due to this growth the energy efficiency in this type of building is essential. There are methodologies to measure this efficiency; one example is PUE (Power Usage Effectiveness). The unit suggested for measuring efficiency at the design stage would be the EUED (Energy Usage Efficiency Design) with this will be used data to use "free cooling" and adiabatic system in some cases, a comparison will be made only considering the equipment in the worst situation. It also uses the study of enthalpy utilization as a new methodology to obtain the results. By doing so, differences were found, between cities than 1.21% of São Paulo in relation to Curitiba and 10.61% of Rio de Janeiro in relation to Curitiba. The indices obtained by applying the EUED index were 1.245 kW.kW- 1 for Curitiba, 1.260 kW.kW-1 for São Paulo and 1.377 kW.kW-1 for Rio de Janeiro, respectively, giving a difference of 16.86% for Curitiba of 16.19% for São Paulo and 10.31% for Rio de Janeiro in relation to PUE COA (Power Usage Effectiveness Constant Outdoor Air).info:eu-repo/semantics/publishedVersio

Refrigeration of COVID-19 Vaccines: Ideal Storage Characteristics, Energy Efficiency and Environmental Impacts of Various Vaccine Options

This article considers the ideal storage conditions for multiple vaccine brands, such as Pfizer, Moderna, CoronaVac, Oxford–AstraZeneca, Janssen COVID-19 and Sputnik V. Refrigerant fluid options for each storage condition, thermal load to cool each type of vaccine and environmental impacts of refrigerants are compared. An energy simulation using the EUED (energy usage effectiveness design) index was developed. The Oxford–AstraZeneca, Janssen COVID-19 and CoronaVac vaccines show 9.34-times higher energy efficiency than Pfizer. In addition, a TEWI (total equivalent warming impact) simulation was developed that prioritizes direct environmental impacts and indirect in refrigeration. From this analysis, it is concluded that the cold storage of Oxford–AstraZeneca, Janssen COVID-19 and CoronaVac vaccines in Brazil generates 35-times less environmental impact than the Pfizer vaccine.info:eu-repo/semantics/publishedVersio