bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modeling of Photovoltaic-Thermal District Heating with Dual Thermal Modes
Authors: Kang Anneka , Korolija Ivan , Rovas Dimitrios 
Published: November 2021

Abstract
Solar photovoltaic thermal (PVT) collectors could be a competitive addition to district heating systems, particularly in areas with high energy density since they simultaneously produce electricity and heat whilst increasing the PV efficiency through cooling. This study presents a new Modelica PVT model, which is used together with EnergyPlus in a co-simulation setup to assess the technical feasibility of solar PVT district heating in new builds. The model has been applied to a block of 12 2-bedroom terraced houses with a 184m2 PVT array on the south facing side of the roof. It was identified that well-designed seasonal PVT heating configurations and control schemes are required to maximise PVT outputs. PVT dual thermal modes occur when the PV is either connected to a load or producing at close to the maximum power point. Integrating the dual modes into a control system could be more economical if heat tariffs were higher than electrical ones when heat demand is greater than the PVT thermal output.
CFD-based surrogate modelling of urban wind farms using artificial neural networks: double rotor arrangements
Authors: Sahebzadeh Sadra , Rezaeiha Abdolrahim , Montazeri Hamid 
Published: November 2021

Abstract
Extensive characterization studies are required to identify optimal wind farm layouts and achieve high power density, i.e., power per land area. Performing such studies using experimental or high-fidelity numerical methods can be timely and computationally expensive. To alleviate this obstacle, surrogate models can be developed to mimic the behavior of the simulation/experiment. In this paper, a shallow feed-forward artificial neural network (ANN) surrogate model is developed. The Levenberg-Marquardt algorithm is used to train a model with 3 layers and 10 hidden nodes. The model correlates the arrangement of a double-rotor vertical axis wind turbine array, as the fundamental generating cell of the wind farm, with its overall power performance. The inputs are the relative distance (R) and angle (®) between the rotors, and the output is the overall power coefficient of the array. In total, 96 CFD-simulated arrangements are used as data points to train, validate and test the model. The trained model has a mean square error of 2.10 × 10-5 and R-squared of 0.99, indicating its accuracy and generalizability. The average and maximum errors are 3% and 10%, respectively. The employed method can be expanded to accommodate more rotors towards optimal urban wind farm layout design.
Exploring light exposure of hospital nurses working rapidly rotating shifts in relation to sleepiness and sleep
Authors: Aarts Mariëlle P.J. , Hartmeyer Steffen L. , Morsink Kars , Kort Helianthe S.M. 
Published: November 2021

Abstract
Nightshift work can negatively impact sleep, performance, and health. Careful manipulation of light exposure patterns can help reduce these negative effects but is challenging in conditions of rapidly rotating shiftwork and due to individual differences. As chronotype is related to shiftwork tolerance, we explored patterns of sleep, sleepiness, and light exposure during the first day of nightshift work between earlier and later chronotypes, based on data from an observational field study among rapidly rotating hospital nurses. Due to the limited sample size, only descriptive analyses and visual inspection were conducted. In line with findings of lower shiftwork tolerance, earlier chronotypes (N=6) seemed to be sleepier during work and sleep less than later types (N=7). Differences were also observed in light exposure patterns, revealing potential for light exposure interventions, and suggesting a contribution to shiftwork tolerance. For future intervention studies in aiming to identify a light exposure strategy, our findings highlight the importance of investigating light exposure relative to the individual circadian phase.
A conceptual simulation workflow to guide design decisions regarding the effects of daylight on occupants’ alertness
Authors: Clotilde Pierson , Eugenia Soto Magán Victoria , Mariëlle Aarts , Marilyne Andersen 
Published: November 2021

AbstractRecent developments in the lighting research field have demonstrated the importance of a proper exposure to light to mediate several of our behavioral and physiological responses. However, we spend nowadays around 90% of our time indoors with an often quite limited access to bright daylight. To be able to anticipate how much the built environment actually influences our light exposure, and how much it may ultimately impact our health, well-being, and productivity, new computational tools are needed. In this paper, we present a first attempt at a simulation workflow that integrates a spectral simulation tool with a light-driven prediction model of alertness. The goal is to optimize the effects of light on building occupants, by informing the decision makers about the impact of different design choices. The workflow is applied to a case study to provide an example of what learnings can be expected from it.
The impact of daylight presence on cooling strategies: energy simulations of a test room in Austin, Texas, and Geneva, Switzerland
Authors: Uckok I T , Addington M , Felkner J 
Published: November 2021

Abstract
In order to understand how to reduce energy consumption in buildings, all factors affecting occupant comfort and behavior must be considered. Previous work from EPFL has elucidated the influence of daylight on thermal perception and its resulting potential to reduce cooling loads in a controlled test space in Geneva, Switzerland with three different illumination levels (130 lux, 600 lux, and 1400 lux) and under three different indoor air temperature levels (19°C, 23°C, 27°C). Occupants perceived the temperature as up to 2°C cooler when exposed to daylight, leading to reduced cooling loads. For climates with high cooling loads for much of the year, such as Austin, Texas, this reduction could yield significant benefits for low-energy building design. Simulations show the total amount of energy saved from adopting this strategy in Austin, Texas.
Data mining for evaluating the rebounds-associated emissions due to energy-related consumer behavioural shifts in Switzerland
Authors: Shinde Rhythima , Peng Sidi , Vijay Saloni , Hellweg Stefanie , Froemelt Andreas 
Published: November 2021

AbstractEnergy-related household consumption lead to a substantial share of the total household GHG emissions (direct and indirect). The policies or technologies, which try to mitigate these emissions often end up ‘rebounding’ i.e. the savings of energy (bills) caused by these measures, induce further expenses in other (e.g. travel) or same (e.g. electricity) categories, leading to (partial) offsetting of the emissions saving. This research introduces application of a data-driven bottom up method to evaluate these rebound emissions based on the household consumption (expenses) and properties. Two scenarios of energy-savings measures are evaluated here: (1) switching to energy-efficient devices, and (2) switching to renewable energy. The results are discussed for households with varying income, region of residence and household size. The results show that higher income and bigger households have higher total rebounds for both scenarios, while Zurich has lowest compared to all other Swiss regions.
Sensitivity analysis of heating a typical UK dwelling and implications for retrofit design
Authors: Simpson Kate , Childs Peter , Whyte Jennifer 
Published: November 2021

Abstract
The aim of this research is to quantify the impact of heating set point on space heating energy demand for a typical UK dwelling. Retrofit includes fabric energy efficiency improvements. Energy performance certificates (EPCs) inform the householder of typical savings per measure, but this has previously been found to inaccurately estimate space heating energy demand, leading to errors in 'typical savings' presented to householders. The most sensitive inputs have been found to be temperature set point, followed by fabric efficiency. The BREDEM methodology assumes a temperature of 21°C for nine hours a day, rather than ~16°C and ~20°C found in research. The methods used to inform this study are local sensitivity analysis of the domestic energy model, based on a typical dwelling example with calibrated inputs. This is done using an open calibrated Python model, based on BREDEM. The impact of heating patterns on space heating energy demand are modelled pre retrofit; according to differing heating set points, following wall and loft fabric upgrade and full fabric upgrade. The BREDEM heating set point assumptions lead to space heating energy demand predicted ~50-100 kWh/m2/yr higher than real heating set points. Implications for retrofit design and EPCs are discussed.
A comparative analysis of quantification and validation methods for prospecting the anthropogenic mine as material reserve for circular construction
Authors: Jawanrudi Damun , McGranahan Joseph , Heisel Felix 
Published: November 2021

Abstract
Globally, buildings account for at least 39% of CO2 emissions and more than 50% of resource extraction and solid waste production. Therefore, any transition to carbon neutral buildings must be paired with new resource sensibilities and a shift from linear models of material consumption to continuous material use within a circular economy. Prospecting the (urban) anthropogenic mine represents an essential step towards circular construction and requires a robust methodology for data collection and interpretation. This paper presents a comparative analysis of survey methods, evaluated by parameters of time, accuracy, equipment, and labor to determine the ability of each tool in providing the necessary data to activate the existing built environment as a material resource. Chosen methods span from on-site manual and analog surveys to off-site digital technologies on a variety of case study scales. In all cases, the output’s data format (sketch book, images, mesh or point cloud outputs) can be cumbersome to process with CAD and BIM software, increasing time to results and limiting the technology’s potential, introducing the call for a new generation of survey tools specifically addressing the needs of deconstruction and salvage in circular construction.
Newman-Janis Ansatz for rotating wormholes
Authors: Gutiérrez-Piñeres A C , Beltrán N H , López-Monsalvo C S 
Published: November 2021

Abstract
A central problem in General Relativity is obtaining a solution to describe the source’s interior counterpart for Kerr black hole. Besides, determining a method to match the interior and exterior solutions through a surface free of predefined coordinates remains an open problem. In this work, we present the ansatz formulated by the Newman-Janis to generate solutions to the Einstein field equation inspired by the mention problems. We present a collection of independent classes of exact interior solutions of the Einstein equation describing rotating fluids with anisotropic pressures. Furthermore, we will elaborate on some obtained solutions by alluding to rotating wormholes.
Forces in Schwarzschild, Vaidya and generalized Vaidya spacetimes
Authors: Vertogradov Vitalii 
Published: November 2021

Abstract
In this paper we investigate how the leading term in the geodesic equation in Schwarzschild spacetime changes under the coordinate transformation to Eddington-Finkelstein coordinates. This term corresponds to the Newton force of attraction. Also we consider this term when we add the energy-momentum tensor of the form of the null dust and the null perfect fluid into right-hand side of the Einstein equation. We estimate the value of this force in Vaidya spacetime when the naked singularity formation occurs. Also we give conditions in generalized Vaidya spacetime when this force of attraction is replaced by the force of repulsion.
Analysis of energy saving in a single-family home project
Authors: Macgregor A A , Gallardo R J , Gómez Camperos J A 
Published: November 2021

Abstract
Electric energy is one of the types of energy that is most present in the activities that human beings carry out daily, hence the importance of making efficient consumption of this resource, especially that which is done in homes, since energy savings represent a reduction in carbon dioxide emissions. Given that the construction sector can represent up to 39% of the carbon dioxide emissions emitted into the atmosphere, this research analyzes the impact generated by the construction and use of a single-family home, with the use of DesignBuilder software. Initially, a model was made under traditional conditions, thus determining where the greatest heat gains were concentrated, followed by a second model under adjusted conditions. A life cycle analysis was made under conditions adjusted to a period of 100 years and the submission of the two conditions to the choosing by advantages method. The results showed that the changes can reduce annual energy consumption by up to 66% and recover the investment in 10 years. Finally, the analysis of the life cycle determined that for a period of 100 years the emissions are 18679.67 equivalent tonnes of carbon dioxide.
Methodology of robust inverted pendulum controllers on a vehicle
Authors: Mesa F , Ospina Ospina R , Devia-Narvaez D M 
Published: November 2021

Abstract
In the theory of controllers, the simple and inverted pendulum play an important role due to the equations that result from them, which imply non-linearities and perturbations, thus, in this article, a brief classification of inverted pendulums is presented: inverted pendulum, inverted double pendulum, inverted rotary pendulum (Furuta pendulum). Subsequently, a mathematical model of the inverted pendulum is described through the deduction of the equations of motion that represent the dynamics of the system. Robust control is presented that allows expanding the richness of the mathematical equations, for this case, a control with output feedback is presented and applied to the inverted pendulum to control the unstable dynamics of this model. The results are compared with a post placement control and a robust control using a norm that analyses the characteristics of the system.
Acoustic emissions in the valuation of the combustion chamber pressure of an engine
Authors: Rojas Suárez J P , Pabón León J A , Orjuela Abril M S 
Published: November 2021

Abstract
Internal combustion engines demand advanced monitoring methodologies to promote efficient operation; particularly, the combustion pressure plays a central role in the overall performance, which promotes the utilization of transducers that hinders. Therefore, the present study introduces an acoustic emission methodology that serves for indirect combustion pressure measurements. Accordingly, the compound methodology integrates the Hilbert transform and the complex cepstrum using neural networks to accomplish pressure signal reconstruction. Results demonstrated that the proposed methodology featured robust performance while estimating pressure signals as it mitigates the combined noise effect produced by variations in engine speed, engine load, and fuel type. Moreover, the reconstructed signal facilitated the determination of key performance parameters such as peak pressure, pressure timing, and effective mean pressure. Relative error amounted to less than 10%, which ratified the robustness of the indirect pressure measurements. In conclusion, acoustic signal techniques represent an adequate approach to estimate the combustion pressure at variable engine conditions.
Analysis of the dispersivity in soils by applying a modified test based on the pinhole method
Authors: Galvis L C , Ruge J C , Olarte M C 
Published: November 2021

Abstract
The Pinhole test is an empirical probe with a qualitative classification foundation that identifies fine-grained soils with dispersive potential using hydraulic heads. However, the original technique was designed to identify dispersive clays. In some cases, it is misused as a quantitative test for measuring subsurface erosion rates. This paper presents a physicochemical modification to the exact test, based on adding a dispersant in the sample compaction water. For the quantitative evaluation of the susceptibility of the soil to generate internal tubification or piping, the effects of hydraulic load, flow, and orifice diameter before and after the execution of the test are explored—both for the samples treated with deflocculant and for those compacted using distilled water. Additionally, to complete the identification results, physical and chemical approaches were applied as methods of comparison. The results obtained from the altered soils indicate a significant increase in the clay fraction among the samples at the end of the test and gains of 3.7 and 6.2 times the initial diameter. The study demonstrates that the modified test is suitable for identifying non-dispersive soils before raising the percolation pressure. This modification is helpful for the improvement of the test because it helps to understand the procedure better and allows to calibrate the apparatus used.
Investigation of high current electron beam dynamics in linear induction accelerator for creation of a high-power THz radiation source
Authors: Nikiforov D.A. , Petrenko A.V. , Sinitsky S.L. , Bak P.A. , Skovorodin D.I. , Logachev P.V. , Zhivankov K.I. , Sandalov E.S. , Meshkov O.I. , Ivanov A.V. , Fuodorov V.V. , Starostenko A.A. , Pavlov O.A. , Kuznetsov G.I. , Krylov A.A. , Starostenko D.A. , Nikitin O.A. , Akhmetov A.R. 
Published: November 2021

Abstract
The work addresses the use of electron beam produced by the
linear induction accelerator to generate terahertz radiation pulses
of 100 MW power level based on a free electron laser scheme. The
beam parameters required for efficient generation are given. The
features of transverse beam dynamics when transporting the beam
through the linac are investigated. Emphasis is put on the electron
injector which geometry and operation parameters mainly determine
the beam characteristics at the linac exit. Most of the possible
factors contributing to the beam emittance gain in the accelerator
are considered. The obtained analytical estimates are compared to
the numerical simulation results. The experimental results on
compressing and transporting the beam having the electron energy of
5 MeV and the current of 1 kA in the transport system of free
electron laser are presented.
Chitosan/β-TCP composites scaffolds coated with silk fibroin: a bone tissue engineering approach
Authors: Piaia Lya , Silva Simone S , Gomes Joana M , R Franco Albina , Fernandes Emanuel M , Lobo Flávia C M , Rodrigues Luísa C , Leonor Isabel B , Fredel Márcio C , Salmoria Gean V , Hotza Dachamir , Reis Rui L 
Published: November 2021

Abstract
Bone regeneration and natural repair are long-standing processes that can lead to uneven new tissue growth. By introducing scaffolds that can be autografts and/or allografts, tissue engineering provides new approaches to manage the major burdens involved in this process. Polymeric scaffolds allow the incorporation of bioactive agents that improve their biological and mechanical performance, making them suitable materials for bone regeneration solutions. The present work aimed to create chitosan/beta-tricalcium phosphate-based scaffolds coated with silk fibroin and evaluate their potential for bone tissue engineering. Results showed that the obtained scaffolds have porosities up to 86%, interconnectivity up to 96%, pore sizes in the range of 60–170 μm, and a stiffness ranging from 1 to 2 MPa. Furthermore, when cultured with MC3T3 cells, the scaffolds were able to form apatite crystals after 21 d; and they were able to support cell growth and proliferation up to 14 d of culture. Besides, cellular proliferation was higher on the scaffolds coated with silk. These outcomes further demonstrate that the developed structures are suitable candidates to enhance bone tissue engineering.
A physiological signal derived from sun-induced chlorophyll fluorescence quantifies crop physiological response to environmental stresses in the U.S. Corn Belt
Authors: Kimm Hyungsuk , Guan Kaiyu , Jiang Chongya , Miao Guofang , Wu Genghong , Suyker Andrew E , Ainsworth Elizabeth A , Bernacchi Carl J , Montes Christopher M , Berry Joseph A , Yang Xi , Frankenberg Christian , Chen Min , Köhler Philipp 
Published: November 2021

Abstract
Sun-induced chlorophyll fluorescence (SIF) measurements have shown unique potential for quantifying plant physiological stress. However, recent investigations found canopy structure and radiation largely control SIF, and physiological relevance of SIF remains yet to be fully understood. This study aims to evaluate whether the SIF-derived physiological signal improves quantification of crop responses to environmental stresses, by analyzing data at three different spatial scales within the U.S. Corn Belt, i.e. experiment plot, field, and regional scales, where ground-based portable, stationary and space-borne hyperspectral sensing systems are used, respectively. We found that, when controlling for variations in incoming radiation and canopy structure, crop SIF signals can be decomposed into non-physiological (i.e. canopy structure and radiation, 60% ∼ 82%) and physiological information (i.e. physiological SIF yield, ΦF, 17% ∼ 31%), which confirms the contribution of physiological variation to SIF. We further evaluated whether ΦF indicated plant responses under high-temperature and high vapor pressure deficit (VPD) stresses. The plot-scale data showed that ΦF responded to the proxy for physiological stress (partial correlation coefficient, r
p= 0.40, p< 0.001) while non-physiological signals of SIF did not respond (p> 0.1). The field-scale ΦF data showed water deficit stress from the comparison between irrigated and rainfed fields, and ΦF was positively correlated with canopy-scale stomatal conductance, a reliable indicator of plant physiological condition (correlation coefficient r= 0.60 and 0.56 for an irrigated and rainfed sites, respectively). The regional-scale data showed ΦF was more strongly correlated spatially with air temperature and VPD (r= 0.23 and 0.39) than SIF (r= 0.11 and 0.34) for the U.S. Corn Belt. The lines of evidence suggested that ΦF reflects crop physiological responses to environmental stresses with greater sensitivity to stress factors than SIF, and the stress quantification capability of ΦF is spatially scalable. Utilizing ΦF for physiological investigations will contribute to improve our understanding of vegetation responses to high-temperature and high-VPD stresses.