Second order SUSY transformations with `complex energies'

Second order supersymmetry transformations which involve a pair of complex conjugate factorization energies and lead to real non-singular potentials are analyzed. The generation of complex potentials with real spectra is also studied. The theory is applied to the free particle, one-soliton well and one-dimensional harmonic oscillator.Comment: 11 pages, 2 figures, submitted on 23 August 2002 to Phys. Lett.

Validation of calibrated energy models: Common errors

Nowadays, there is growing interest in all the smart technologies that provide us with information and knowledge about the human environment. In the energy ¿eld, thanks to the amount of data received from smart meters and devices and the progress made in both energy software and computers, the quality of energy models is gradually improving and, hence, also the suitability of Energy Conservation Measures (ECMs). For this reason, the measurement of the accuracy of building energy models is an important task, because once the model is validated through a calibration procedure, it can be used, for example, to apply and study different strategies to reduce its energy consumption in maintaining human comfort. There are several agencies that have developed guidelines and methodologies to establish a measure of the accuracy of these models, and the most widely recognized are: ASHRAE Guideline 14-2014, the International Performance Measurement and Veri¿cation Protocol (IPMVP) and the Federal Energy Management Program (FEMP). This article intends to shed light on these validation measurements (uncertainty indices) by focusing on the typical mistakes made, as these errors could produce a false belief that the models used are calibrated

Towards a new generation of building envelope calibration

Building energy performance (BEP) is an ongoing point of reflection among researchers and practitioners. The importance of buildings as one of the largest activators in climate change mitigation was illustrated recently at the United Nations Framework Convention on Climate Change 21st Conference of the Parties (COP21). Continuous technological improvements make it necessary to revise the methodology for energy calculations in buildings, as has recently happened with the new international standard ISO 52016-1 on Energy Performance of Buildings. In this area, there is a growing need for advanced tools like building energy models (BEMs). BEMs should play an important role in this process, but until now there has no been international consensus on how these models should reconcile the gap between measurement and simulated data in order to make them more reliable and affordable. Our proposal is a new generation of models that reconcile the traditional data-driven (inverse) modelling and law-driven (forward) modelling in a single type that we have called law-data-driven models. This achievement has greatly simpli¿ed past methodologies, and is a step forward in the search for a standard in the process of calibrating a building energy model

Some properties of Multiplication Operators acting on Banach spaces of measurable functions

The purpose of this article is to survey the recent results about the properties of multiplication operators acting on Banach spaces of measurable functions. Most of them was presented by the author in a conference held in Bogotá 2016, on the occasion of celebrating the "IV UN Encuentro de Matemáticas" at the "Universidad Nacional de Colombia"

Group theoretical approach to the intertwined Hamiltonians

We show that the finite difference B\"acklund formula for the Schr\"odinger Hamiltonians is a particular element of the transformation group on the set of Riccati equations considered by two of us in a previous paper. Then, we give a group theoretical explanation to the problem of Hamiltonians related by a first order differential operator. A generalization of the finite difference algorithm relating eigenfunctions of {\emph three} different Hamiltonians is found, and some illustrative examples of the theory are analyzed, finding new potentials for which one eigenfunction and its corresponding eigenvalue is exactly known

Occupational factors associated with health-related quality of life in nursing professionals: a multi-centre study

Background: Nursing professionals are exposed to stressful situations arising from the work context that may affect health-related quality of life (HRQoL). The objective of this study was to analyse the relationship between sociodemographic and work-related variables regarding HRQoL in nursing professionals. Methods: A multi-centre, cross-sectional descriptive design was used. The participants consisted 1521 nurses working in healthcare centres, in both primary care and hospital care, in the eight provinces of the Andalusian Public Health System (APHS), Spain. Sociodemographic and work-related variables were analysed: Compassion fatigue, compassion satisfaction and burnout were measured using the professional quality of life questionnaire (ProQOL), and HRQoL was measured using the SF-12 health questionnaire. Results: Compassion fatigue, burnou, and, to a lesser extent, compassion satisfaction significantly influence the physical and mental components of HRQoL. The simple regression analysis showed that burnout and compassion fatigue were significantly associated with the mental component of HRQoL. Gender influenced the mental component of HRQoL. The rest of the sociodemographic and work-related variables were not significantly related to HRQoL. Conclusion: Work-related stress and repeated contact with situations of suffering influence HRQoL. Health systems must implement programmes to increase the emotional well-being of workers

Probabilistic load forecasting for building energy models

In the current energy context of intelligent buildings and smart grids, the use of load forecasting to predict future building energy performance is becoming increasingly relevant. The prediction accuracy is directly influenced by input uncertainties such as the weather forecast, and its impact must be considered. Traditional load forecasting provides a single expected value for the predicted load and cannot properly incorporate the effect of these uncertainties. This research presents a methodology that calculates the probabilistic load forecast while accounting for the inherent uncertainty in forecast weather data. In the recent years, the probabilistic load forecasting approach has increased in importance in the literature but it is mostly focused on black-box models which do not allow performance evaluation of specific components of envelope, HVAC systems, etc. This research fills this gap using a white-box model, a building energy model (BEM) developed in EnergyPlus, to provide the probabilistic load forecast. Through a Gaussian kernel density estimation (KDE), the procedure converts the point load forecast provided by the BEM into a probabilistic load forecast based on historical data, which is provided by the building’s indoor and outdoor monitoring system. An hourly map of the uncertainty of the load forecast due to the weather forecast is generated with different prediction intervals. The map provides an overview of different prediction intervals for each hour, along with the probability that the load forecast error is less than a certain value. This map can then be applied to the forecast load that is provided by the BEM by applying the prediction intervals with their associated probabilities to its outputs. The methodology was implemented and evaluated in a real school building in Denmark. The results show that the percentage of the real values that are covered by the prediction intervals for the testing month is greater than the confidence level (80%), even when a small amount of data are used for the creation of the uncertainty map; therefore, the proposed method is appropriate for predicting the probabilistic expected error in load forecasting due to the use of weather forecast data