bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of Ekman friction on the velocity profile of a coherent vortex in a three-dimensional rotating turbulent flow
Authors: Parfenyev Vladimir M. , Vergeles Sergey S.
Published: November 2021

In the presence of strong background rotation, the velocity field tends to become quasi-two-dimensional, which leads to the inverse energy cascade. If the damping is small enough, then the energy is accumulated at the largest scales of the system, forming coherent columnar vortex structures known as condensates. Recently, it was found that the radial velocity profiles of axisymmetric cyclones and anticyclones are described by the dependence UGφ(r)=±ϵ/ν r ln (R/r), where ϵ is statistically stationary turbulent forcing power per unit mass, ν is the kinematic viscosity of a fluid, and R is the transverse size of the vortex. However, the corresponding theory did not take into account the boundary effects and, therefore, was mainly applicable to numerical simulations with periodic boundary conditions. Here, we demonstrate that for typical experimental conditions, the damping of the condensate far enough from the symmetry axis is determined by the linear Ekman friction α=2Ω0E1/2 associated with the no-slip conditions at the lower and upper boundaries of the system, where Ω0 is the angular velocity of the background rotation and E is the Ekman number. In this case, the azimuthal velocity of the coherent vortex does not depend on the distance to the vortex center and is determined by the expression UGφ=±3ϵ/α. We discuss the structure of the coherent vortex in this case and compare the results with velocity profiles of condensates in two-dimensional systems.
Requesting early removal of long-acting reversible contraception: a qualitative study exploring the experiences of doctors working in primary care
Authors: Ding Jacqueline , Williams Henrietta , Hocking Jane S. , Coombe Jacqueline
Published: November 2021

Long-acting reversible contraceptives (LARC) are the most effective contraceptive methods available in Australia and are effective for between 3 and 8 years. Early LARC removal (<12 months of use) can lead to gaps in contraceptive cover, exposing women to the risk of unplanned pregnancy. This study explored the experiences of doctors working in primary care (GPs and sexual health physicians) when asked to remove LARC earlier than expected. From May to July 2020, 13 doctors in Melbourne, Australia, were interviewed. Overall, participants felt conflicted about early LARC removal requests; participants highlighted the importance of respecting patient autonomy, but many felt that patients should ideally persist with LARC longer. Participants found balancing a desire to respect patients’ autonomy with their clinical responsibility challenging. Doctors used reassurance, delaying tactics and treatment of side effects to try and prolong LARC use. However, this balancing act led many doctors to perceive a tension between themselves and their patients when early LARC removal was requested. Incorporating professional education addressing these issues may help primary care providers better anticipate and navigate the tension surrounding early LARC removal consultations and maintain effective doctor–patient relationships.
PD-L1 sustains chronic, cancer cell–intrinsic responses to type I interferon, enhancing resistance to DNA damage
Authors: Cheon HyeonJoo , Holvey-Bates Elise G. , McGrail Daniel J. , Stark George R.
Published: November 2021

Significance

Cancer cell–intrinsic IFN-I responses can have opposite effects in response to DNA damage, either facilitating or inhibiting cytotoxicity. We found that PD-L1 regulates these seemingly paradoxical effects, inhibiting the cytotoxic acute response to high levels of IFN-I but sustaining the protective chronic response to constitutive low levels of IFN-I. This revealed facet of PD-L1 activity operates independently of the cancer cell–extrinsic immune system. Our improved understanding of the functions of PD-L1 in cancer informs more effective strategies to target PD-L1 and block both its cell-intrinsic and its immune-dependent functions.
Multisubstrate DNA stable isotope probing reveals guild structure of bacteria that mediate soil carbon cycling
Authors: Barnett Samuel E. , Youngblut Nicholas D. , Koechli Chantal N. , Buckley Daniel H.
Published: November 2021

Significance

Soil organic matter contains a large fraction of global C whose fate is largely governed by soil microbial communities. Global C-cycle models can be improved using information about microbial processes in soil, but the inner workings of soil communities remain largely hidden from view. We used stable isotopes to characterize the guild structure of soil bacteria based on how they assimilated C from different sources. Guild structure corresponded with growth dynamics and
rrn
copy number. We also show that this guild structure explains microbial biogeographical patterns at continental and global scales. These results suggest that microbial contributions to soil C cycling are largely governed by an anabolic process that governs energy allocation to growth, competition, and survival.
Diversifying and enhancing mountainous destinations through rural tourism: the case of Kalavrita, Greece.
Authors: Boukas Nikolaos
Published: November 2021

The chapter emphasizes the tourism products that the destination offers, highlighting rural tourism as a macro niche that is worthy to be considered as a unique form of tourism, and suggests a series of strategies for the diversification and enhancement of the tourism offering for the holistic Greek destination experience. In this regard, this study was employed for: (i) discovering the role of rural tourism for the mountainous area of Kalavrita, highlighting the challenges and opportunities of the current tourism situation in the area; (ii) analysing the strategies formulated by tourism authorities to engage in rural tourism; and (iii) conceptualizing the current and potential rural tourism products that do, and could, lead to the appropriate diversification of the existing tourism product of the Kalavrita region, as a representative western European mountainous destination.
Fine-tuning activity-dependent bulk endocytosis via kinases and phosphatases
Authors: Milosevic Ira , Cousin Michael A.
Published: November 2021

The regulation of activity-dependent bulk endocytosis, the dominant mode of membrane retrieval in response to intense neuronal activity, is poorly understood. In this JCB issue, Peng et al. (2021. J. Cell. Biol.https://doi.org/10.1083/jcb.202011028) propose a novel molecular mechanism for the coordination of activity-dependent bulk endocytosis that builds on Minibrain kinase and its presynaptic substrate synaptojanin-1.
Investigation of mechanical, thermodynamical, dynamical and electronic properties of RuYAs (Y
= Cr and Fe) alloys
Authors: Kalita Dipangkar , Ram Mahesh , Limbu Nihal , Saxena Atul
Published: November 2021

Investigation of structural, dynamical, mechanical, electronic and thermodynamic properties of RuYAs (Y = Cr and Fe) alloys have been performed from the first principle calculations. Among the three structural phases, ‘α’ phase is found to be energetically favorable for both the RuCrAs and RuFeAs compounds. The computed cohesive energies and phonon dispersion spectra indicate the structural and dynamical stabilities of both the compounds. Mechanical stability of these compounds are studied using elastic constants. The Pugh’s ratio predicts RuFeAs to be more ductile than RuCrAs. The RuCrAs alloy, on the other hand, is found to be a stiffer, harder and highly rigid crystal with stronger bonding forces than the RuFeAs. Furthermore, the thermodynamical properties have also been estimated with respect to the temperature under different pressures using the quasi-harmonic Debye model. In order to account for the effect of the highly correlated d transition elements in the system we incorporated the GGA + U approximations. Within the GGA + U approach, the electronic structure reveals the half-metallicity for both compounds, which follows the Slater–Pauling rule. The charge density and electron localized function reflect the covalent bonding among the constituent atoms. Bader analysis reveals that the charge transfer takes place from Cr/Fe to Ru and As atoms in both approximations. Both Raman and infrared active modes have been identified in the compounds.
Hermite-Chebyshev pseudospectral method for inhomogeneous superconducting strip problems and magnetic flux pump modeling
Authors: Sokolovsky Vladimir , Prigozhin Leonid
Published: November 2021

The numerical simulation of superconducting devices is a powerful tool for understanding the principles of how they work and improving their design. Usually, these simulations are based on a finite element method but, recently, a different approach, based on the spectral technique, has been presented for very efficient solution of several applied superconductivity problems described by 1D integro-differential equations or a system of such equations. Here, we propose a new pseudospectral method for 2D magnetization and transport current superconducting strip problems with an arbitrary current–voltage relation, spatially inhomogeneous strips and strips in a nonuniform applied field. The method is based on bivariate expansions in Chebyshev polynomials and Hermite functions. It can be used for numerical modeling of magnetic flux pumps of different types and investigating AC losses in coated conductors with local defects. Using a realistic 2D version of the superconducting dynamo benchmark problem as an example, we show that our new method is a competitive alternative to finite element methods.
Erosion of tungsten marker layers in W7-X
Authors: Mayer M , Balden M , Brezinsek S , Dhard C P , Elgeti S , Fajardo D , Fellinger J , Guitart Corominas M , Hiret P , Kandler M , Krause M , Loesser D , Lumsdaine A , Naujoks D , Neilson H , Neu R , Oelmann J , Ruset C , Schmidt-Dencker J-H
Published: November 2021

In order to get first insight into net tungsten erosion in W7-X, tungsten (W) marker layers were exposed during the operational phase OP 1.2b at one position of the Test Divertor Unit (TDU), at 21 different positions of the inner heat shield, and at two scraper elements. The maximum tungsten erosion rate at the TDU strike line was 0.13 nm s−1 averaged over the whole campaign. The erosion was inhomogeneous on a microscopic scale, with higher erosion on ridges of the rough surface inclined towards the plasma and deposition of hydrocarbon layers in the recessed areas of the rough surface. The W erosion at the inner heat shield was below the detection limit of 3–6 × 1012 W-atoms/cm2s, and all inner heat shield tiles were covered with a thin B/C/O layer with thickness in the range 2 × 1017–1018 B + C atoms/cm2 (about 20–100 nm B + C). W-erosion of the marker layers on the scraper elements was also below the detection limit.
Fabricating tritium permeation barrier for PFC with a new non-coating strategy
Authors: Wang Lu , Zhou Hai-Shan , Liu Hao-Dong , Xu Yu-Ping , Wang Wan-Jing , Li Yan-Fen , Luo Guang-Nan
Published: November 2021

Tritium (T) permeation through plasma-facing component (PFC) into the coolant is a major concern of fusion reactor operation. In this work, deuterium (D) permeation through CLAM steel, CLAM/CLAM and CLAM/Fe-Cr-Al samples prepared by hot isostatic pressing (HIP) are tested in a linear plasma device. Only the downstream surfaces of the samples are oxidized with controlled atmosphere to form permeation barrier. No significant effect on D diffusion and penetration can be observed for the joining interfaces, while the dense oxide layer at the downstream side plays an important role in suppressing D permeation. The downstream surface oxidization of CLAM/Fe-Cr-Al is found to effectively reduce D permeation flux by a factor up to 1000.
Long-term in-vivo recording performance of flexible penetrating microelectrode arrays
Authors: Jang Jae-Won , Kang Yoo Na , Seo Hee Won , Kim Boil , Choe Han Kyoung , Park Sang Hyun , Lee Maan-Gee , Kim Sohee
Published: November 2021

Objective. Neural interfaces are an essential tool to enable the human body to directly communicate with machines such as computers or prosthetic robotic arms. Since invasive electrodes can be located closer to target neurons, they have advantages such as precision in stimulation and high signal-to-noise ratio (SNR) in recording, while they often exhibit unstable performance in long-term in-vivo implantation because of the tissue damage caused by the electrodes insertion. In the present study, we investigated the electrical functionality of flexible penetrating microelectrode arrays (FPMAs) up to 3 months in in-vivo conditions. Approach. The in-vivo experiment was performed by implanting FPMAs in five rats. The in-vivo impedance as well as the action potential (AP) amplitude and SNR were analyzed over weeks. Additionally, APs were tracked over time to investigate the possibility of single neuron recording. Main results. It was observed that the FPMAs exhibited dramatic increases in impedance for the first 4 weeks after implantation, accompanied by decreases in AP amplitude. However, the increase/decrease in AP amplitude was always accompanied by the increase/decrease in background noise, resulting in quite consistently maintained SNRs. After 4 weeks of implantation, we observed two distinctive issues regarding long-term implantation, each caused by chronic tissue responses or by the delamination of insulation layer. The results demonstrate that the FPMAs successfully recorded neuronal signals up to 12 weeks, with very stably maintained SNRs, reduced by only 16.1% on average compared to the first recordings, although biological tissue reactions or physical degradation of the FPMA were present. Significance. The fabricated FPMAs successfully recorded intracortical signals for 3 months. The SNR was maintained up to 3 months and the chronic function of FPMA was comparable with other silicon based implantable electrodes.
Randomness of Möbius coefficients and Brownian motion: growth of the Mertens function and the Riemann hypothesis
Authors: Mussardo Giuseppe , LeClair André
Published: November 2021

The validity of the Riemann hypothesis (RH) on the location of the non-trivial zeros of the Riemann ζ-function is directly related to the growth of the Mertens function

M

(

x

)

=

∑

k
=
1

x

μ

(

k

)

, where μ(k) is the Möbius coefficient of the integer k; the RH is indeed true if the Mertens function goes asymptotically as M(x) ∼ x
1/2+ϵ
, where ϵ is an arbitrary strictly positive quantity. We argue that this behavior can be established on the basis of a new probabilistic approach based on the global properties of the Mertens function, namely, based on reorganizing globally in distinct blocks the terms of its series. With this aim, we focus attention on the square-free numbers and we derive a series of probabilistic results concerning the prime number distribution along the series of square-free numbers, the average number of prime divisors, the Erdős–Kac theorem for square-free numbers, etc. These results point to the conclusion that the Mertens function is subject to a normal distribution as much as any other random walk. We also present an argument in favor of the thesis that the validity of the RH also implies the validity of the generalized RH for the Dirichlet L-functions. Next we study the local properties of the Mertens function, i.e. its variation induced by each Möbius coefficient restricted to the square-free numbers. Motivated by the natural curiosity to see how closely to a purely random walk any sub-sequence is extracted by the sequence of the Möbius coefficients for the square-free numbers, we perform a massive statistical analysis on these coefficients, applying to them a series of randomness tests of increasing precision and complexity; together with several frequency tests within a block, the list of our tests includes those for the longest run of ones in a block, the binary matrix rank test, the discrete Fourier transform test, the non-overlapping template matching test, the entropy test, the cumulative sum test, the random excursion tests, etc, for a total of 18 different tests. The successful outputs of all these tests (each of them with a level of confidence of 99% that all the sub-sequences analyzed are indeed random) can be seen as impressive ‘experimental’ confirmations of the Brownian nature of the restricted Möbius coefficients and the probabilistic normal law distribution of the Mertens function analytically established earlier. In view of the theoretical probabilistic argument and the large battery of statistical tests, we can conclude that while a violation of the RH is strictly speaking not impossible, it is however extremely improbable.
Nonplanar Tiled 1-bit Transmitarray with Phase Error Compensation
Authors: Kirillov V V , Turalchuk P A
Published: November 2021

A phase compensation method for 1-bit phase quantized transmitarray is discussed. Using the tiled architecture of the transmitarray, the position of each unit cell is changed along the optical axis of the transmitarray. The spatial displacement allows changing the resulting phase distribution along the transmitarray aperture. Analytical calculations were performed to demonstrate the performance of the transmitarray radiation pattern.
An adaptive control framework based on Reinforcement learning to balance energy, comfort and hygiene in heat pump water heating systems
Authors: Heidari Amirreza , Marechal Francois , Khovalyg Dolaana
Published: November 2021

A major challenge in the operation of water heating systems lies in the highly stochastic nature of occupant behavior in hot water use, which varies over different buildings and can change over the time. However, the current operational strategies of water heating systems are detached from occupant behavior, and follow a conservative and energy intensive approach to ensure the availability of hot water any time it is demanded. This paper proposes a Reinforcement learning-based control framework which can learn and adapt to the occupant behavior of each specific building and make a balance between energy use, occupant comfort and water hygiene. The proposed framework is compared to the conventional approach using the real-world measurements of hot water use behavior in a single family residential building. Although the monitoring campaign has been executed during home lockdown due to COVID-19, when the occupants exhibited a very different schedule and water use related behavior, the proposed framework has learned the occupant behavior over a relatively short period of 8 weeks and provided 24.5% energy use reduction over the conventional approach, while preserving occupant comfort and water hygiene.
Artificial Intelligence for Detecting Indoor Visual Discomfort from Facial Analysis of Building Occupants
Authors: Johra Hicham , Gade Rikke , Poulsen Mathias Østergaard , Christensen Albert Daugbjerg , Khanie Mandana Sarey , Moeslund Thomas , Jensen Rasmus Lund
Published: November 2021

Glare is a common local visual discomfort that is difficult to identify with conventional light sensors. This article presents an artificial intelligence algorithm that detects subjective local glare discomfort from the image analysis of the video footage of an office occupant’s face. The occupant’s face is directly used as a visual comfort sensor. Results show that it can recognize glare discomfort with around 90% accuracy. This algorithm can thus be at the basis of an efficient feedback control system to regulate shading devices in an office building.
Evaluation of linear and nonlinear system models in hierarchical model predictive control of HVAC systems
Authors: Eser Steffen , Stoffel Phillip , Kumpel Alexander , Muller Dirk
Published: November 2021

Buildings are responsible for one third of the global final energy consumption. Model predictive control (MPC) can reduce their energy consumption and improve thermal comfort. However, designing the required models can be time consuming. Splitting the control problem into smaller subproblems could make the modeling process more modular and therefore cheaper. A hierarchical MPC structure is proposed in this work, where the building model is divided into a lower layer consisting of the producer side and an upper layer consisting of the consumers. Linear and non-linear model equations as well as a cost-based and a control quality-based cost function for a building energy system are developed. In a simulation, the nonlinear controller outperforms the linear controller in both constraint satisfaction and energy costs.
Comparative study of neural network based and white box model predictive control for a room temperature control application
Authors: Stoffel Phillip , Berktold Max , Gall Arman , Kiimpel Alexander , Muller Dirk
Published: November 2021

On a global scale, buildings are a major cause for primary energy consumption. Since buildings are complex multiple input multiple output systems and characterized by slow dynamics, model predictive control is a promising approach to reduce building energy consumption. Due to the high individual modeling effort model predictive control lacks practical applicability. For that reason black box process models are gaining more and more interest in scientific literature. In this work we evaluate the performance of an ANN based controller against a white box controller with perfect knowledge. We show that the data driven controller achieves a similar control quality as the white box controller. We initially train the data driven controller in 20 days and then employ an online learning strategy to continuously improve the control quality.
The influence of perceived environmental quality on thermal comfort in an outdoor urban environment during hot summer
Authors: Lau Kevin Ka-Lun , Choi Chun Yin
Published: November 2021

Thermal comfort in outdoor spaces is essential for human health and human wellbeing. A comfortable outdoor space enhances urban livability and sustainability. Previous studies on outdoor human thermal comfort highlighted that apart from the microclimate conditions, the psychological and physiological factors play an important role in human thermal comfort. The influence of environmental quality on human thermal comfort is being examined in this paper. A survey with a total of 1842 thermal comfort responses was conducted during a hot summer in Hong Kong. Perceived aesthetic and acoustic quality votes are strongly associated with Thermal Sensation Votes (TSV). Thermal Comfort Votes (TCV) in the satisfied aesthetic group and the satisfied acoustic group are significantly higher than that in the not satisfied group. A sensation of comfort was confirmed by 39.8% and 38.4% of participants in the satisfied aesthetic group and the satisfied acoustic group, while only 22.2% and 23.9% of the members of the not satisfied group felt comfortable. The study suggested that the perceived environmental qualities are highly associated with thermal sensation and thermal comfort, and a beautiful and quiet environment can improve the thermal comfort and thermal tolerance.
Impact of volume distribution on pedestrian wind environment in high-rise urban districts: a CFD study
Authors: Sadeghfar Milad , Sahebzadeh Sadra
Published: November 2021

Pedestrian wind environment assessment is becoming an essential part of the urban design process especially in dense urban areas due to its ability to address the wind comfort/safety/health concerns in an early phase. In this paper, high-fidelity computational fluid dynamics (CFD) simulations, validated with experimental data, are performed on eight different designs in a generic urban layout to study the impact of volume distribution on pedestrian wind environment in high-rise urban districts. The results show that the blockage effects of the high-rise buildings decelerates the wind in the streets parallel to the flow while accelerating the flow in the streets perpendicular to the flow. This effect is evident up to a two block distance upstream of the high-rises. Furthermore, it is shown that consequent rows of high-rises in the downstream of the first row facing the wind flow have little effect on the upstream pedestrian wind; however, they have a significant role in the extent of affected areas downstream. The findings of this study provide further understanding about the impact of different volume distributions on pedestrian wind environment in high-rise urban districts and clarify their effect on wind safety and comfort.
A tool for automated detection of hidden operation modes in building energy systems
Authors: Storek Thomas , Kriwet Jonathan , Kümpel Alexander , Müller Dirk
Published: November 2021

The integration of renewable energy sources into building energy systems and the progressive coupling between the thermal and electrical domains makes the analysis of these systems increasingly complex. At the same time, however, more and more building monitoring data is being collected. The manual evaluation of this data is time-consuming and requires expert knowledge. Hence, there is a strong need for tools that enable the automatic knowledge extraction from these huge data sets to support system integrators and favor the development of smart energy services, e.g., predictive maintenance. One crucial step in knowledge extraction is the detection of change points and hidden states in measurements. In this work, we present a tool for automated detection of hidden operation modes based on multivariate time series data deploying motif-aware state assignment (MASA). The tool is evaluated utilizing measurements of a heat pump and compared to two baseline algorithms, namely k-Means and k-Medoids. MASA performs particularly well on noisy data, where it shows only a small deviation in the number of detected change points compared to the ground truth with up to 77% accuracy. Furthermore, it almost always outperforms the baseline algorithms, which in turn require extensive preprocessing.
BIM in Early Design Phase: Workflow for Preliminary Assessment with SBToolCZ
Authors: Veselka J , Hájek J , Volf M , Růžička J , Žd’ára V
Published: November 2021

Early design phase provides the highest potential for saving emissions and energy. Building Information Modeling (BIM) in cooperation with environmental assessment can be efficient tools for various kinds of analysis. This paper shows a possible workflow of using data from BIM in an online form for an early building assessment. Different methods of data export are also described. Czech national methodology, SBToolCZ was used for this study. However, the described principles are applicable for any other commonly used method. Results show approximately 60% of precision compared to the full SBToolCZ assessment (depends on the building typology). As an outcome of the study, a free online tool for architects and public usage is being developed.
Modeling of Photovoltaic-Thermal District Heating with Dual Thermal Modes
Authors: Kang Anneka , Korolija Ivan , Rovas Dimitrios
Published: November 2021

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

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

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

Recent 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

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

Energy-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

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

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

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

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

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

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

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

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

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

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.