bluuebunny/crossref_metadata_2025 huggingface dataset:
The Impact of Language and Location on the Curriculum Preferences of Online Entrepreneurship Students: An Application of Google Analytics
Authors: Starbird S. Andrew , Martin Jill M. , Kalbas-Schmidt Trish A.
Published: January 2022

The needs and interests of online learners can be difficult to assess. Large, self-paced, open courses attract learners from different locations, ethnicities, and educational backgrounds. It is critical that instructors and institutions understand the needs and interests of their learners so that curriculum and pedagogy can evolve. In this paper we consider the curriculum preferences of online learners who are accessing asynchronous, self-selected, and self-paced training content related to entrepreneurship. The content is free and is offered in both English and Spanish. We utilize data from Google Analytics, a free application that records critical data about the demographics and behavior of online users, to test hypotheses about the influence of language and location on the preferences and engagement of learners. We find statistically significant differences in the interests and engagement of learners to Spanish content as opposed to our English content. Similarly, we find that location has a statistically significant impact on the curriculum interests and engagement of learners. Using this information, we can design curriculum that is more closely aligned with the interests of our learners and allocate resources to improve pedagogy.
The Relationship between Teacher Candidates’ Affective Dispositions and Instructional Planning Actions in STEM
Authors: Burton Megan , Maiorca Cathrine , Tripp Lucretia Octavia
Published: January 2022

This study explores the relationship between elementary teacher candidate affective dispositions and the action of STEM lesson planning. While affective dispositions are important, understanding the connection between dispositions and practice is key. Teacher candidates’ affective dispositions about STEM education and instructional planning were examined after participating in a virtual STEM experience. Seventeen elementary teacher candidates experienced STEM instruction via summer virtual courses and field placements. This article focuses on responses to questions about affective dispositions that were coded using inductive analysis. Dispositions towards the following themes were identified: ways to teach integrated STEM, use of inquiry and open ended questions, and confidence. Early childhood lesson plans were coded deductively using the characteristics of model-eliciting activities. Analysis of the data found that teacher candidates who experienced learning, observing, and planning via virtual experiences demonstrated positive affective dispositions towards teaching STEM. However, there were areas of disconnect between the affective dispositions expressed and the instructional action of planning STEM lessons. The data suggest the experiences of learning, observing, and planning STEM lessons can be meaningful in professional growth, but that more needs to be done beyond these experiences to create synergy between instructional actions and affective dispositions related to STEM education.
Early Elementary Students’ Use of Shape and Location Schemas When Embedding and Disembedding
Authors: Bofferding Laura , Chen Lizhen , Kocabas Sezai , Aqazade Mahtob
Published: January 2022

Elementary students’ early development of embedding and disembedding is complex and paves the way for later STEM learning. The purpose of this study was to clarify the factors that support students’ embedding (i.e., overlapping shapes to form a new shape) and disembedding (i.e., identifying discrete shapes within another shape) through the use of filled shapes as opposed to shape frames. We recruited 26 Grade 1 students (~6–7 years old) and 23 Grade 3 students (~8–9 years old), asked them to work on two layered puzzle designs from the Color Code puzzle game, and interviewed them about their thinking processes. The first graders had higher success rates at fixing and embedding the tiles correctly, and students at both grade levels improved on the three-tile design when encountering it a second time about two months later. The four-tile design was more difficult, but students improved if they could identify a correct sub-structure of the design. Successful students used a combination of pictorial shape strategies and schematic location strategies, systematically testing tiles and checking how they could be embedded. The results suggest that helping students focus on sub-structures can promote their effective embedding.
“[Culture] Makes Each Country Unique, It’s Kind of like a Trademark.” Empirical Results on Students’ Perceptions of Culture and Space as Learning Prerequisite for Geography Lessons
Authors: Ege Ronja , Budke Alexandra
Published: January 2022

Students’ everyday perceptions of culture and space have a significant impact on their social coexistence and should, therefore, be considered in geography lessons. The other or foreign is often negatively assessed. This perception is based on an essentialist understanding of cultural space but is inappropriate for a culturally diverse world. The concept of transculturality by Wolfgang Welsch offers a constructivist perspective on culture and space, which takes cultural globalization into account and avoids a stereotyped division of cultures. To prevent xenophobia, it is important to understand the everyday ideas about culture and space younger generations possess and the extent to which transculturality is integrated. The learning requirements of students provide a basis on which geography lessons can be developed that incorporate these concepts to counteract xenophobia. To determine everyday perceptions, 197 German 9th-grade students were asked. The selection of the sample was based on a declaration of consent from the parents and was not fully probabilistic. In addition to a preliminary study, 98 female and 99 male students were surveyed in a written questionnaire. The data analysis was realized in a mixed-method design, with qualitative content analysis and supplementary quantifications. The results of which suggested that culture and space are predominantly understood as nationally specific. Consequently, a transcultural understanding should be incorporated long-term into geography lessons.
Model Predictive Operation Control of Islanded Microgrids under Nonlinear Conversion Losses of Storage Units
Authors: Gholami Milad , Pisano Alessandro
Published: January 2022

This paper proposes a certainty equivalence model predictive control (MPC) approach for the operation of islanded microgrids with a very high share of renewable energy sources. First, to make the MG model more realistic, the conversion losses of the storage units and the conversion losses of the power electronic devices are considered by the quadratic functions in the dynamic of units. Then, to mitigate the effect of errors in the storage units’ state of charge prediction, the conversion loss functions are reformulated by the mixed-integer linear inequality functions and included in the proposed scheme. Finally, the effectiveness of the proposed certainty MPC is verified by a numerical case study.
Performance Assessment of Collective Perception Service Supported by the Roadside Infrastructure
Authors: Correia Marco , Almeida João , Bartolomeu Paulo C. , Fonseca José A. , Ferreira Joaquim
Published: January 2022

To mitigate road-related problems such as safety and traffic congestion, the evolution towards cooperative communicating technologies and autonomous systems is considered a solution to overcome human physical limitations and the limited perception horizon of on-board sensors. This paper describes the implementation of the Collective Perception Service (CPS) in a real road infrastructure with the goal of providing information to automated vehicles and to a central road operator. The Collective Perception Messages are built by retrieving information from traffic classification radars for local dissemination using ITS-G5 radio technology and for broader access by disseminating the messages into a central entity. The service is improved by applying some rules for optimizing the message dissemination in order to increase radio channel efficiency. The results of the experimental tests showed that the end-to-end delay between the production event of the Collective Perception Message (CPM) and the reception by other ITS stations is within the boundaries defined by ETSI standards. Moreover, the algorithm for message dissemination also shows improvement in the radio channel efficiency by limiting the number of objects disseminated by CPM messages. The developed Collective Perception Service and the road infrastructure are, therefore, a valuable asset to provide useful information for increasing road safety and fostering the deployment of Cooperative, Connected and Automated Mobility (CCAM) applications.
A Miniaturized Quartz Crystal Microbalance (QCM) Measurement Instrument Based on a Phase-Locked Loop Circuit
Authors: Park Jong-Yoon , Pérez Rocío L. , Ayala Caitlan E. , Vaughan Stephanie R. , Warner Isiah M. , Choi Jin-Woo
Published: January 2022

The quartz crystal microbalance (QCM) has been widely used in laboratory settings as an analytical tool for recognizing and discriminating biological and chemical molecules of interest. As a result, recent studies have shown there to be considerable attention in practical applications of the QCM technique beyond the laboratory. However, most commercial QCM instruments are not suitable for off-laboratory usage. For field-deployable applications and in situ detection, the development of a portable QCM measurement system achieving comparable performance to benchtop instruments is highly desired. In this paper, we describe the development of a fully customizable, miniaturized, battery-powered, and cost-efficient QCM system employing a phase-locked loop (PLL) electronic circuit-based QCM measurement system. The performance of this developed system showed a minimum frequency resolution of approximately 0.22 Hz at 0.1 s measurement time. This novel, miniaturized system successfully demonstrated an ability to detect two common volatile organic compounds (VOCs), methanol and dichloromethane (DCM), and the obtained results were comparable to responses from a commercially available benchtop instrument.
Neighboring-Pixel-Based Maximum Power Point Tracking Algorithm for Partially Shaded Photovoltaic (PV) Systems
Authors: Rehman Huma , Murtaza Ali Faisal , Sher Hadeed Ahmed , Noman Abdullah M. , Al-Shamma’a Abdullrahman A. , Alkuhayli Abdulaziz , Spertino Filippo
Published: January 2022

In this paper, a neighboring-pixel-based virtual imaging (NPBVI) technique is developed to comprehensively detect the shading conditions on PV arrays. The proposed VI technique is then merged with a probabilistic mechanism of shaded module currents. Finally, a mathematical model is presented, which predicts the current voltage (I-V) region corresponding to the global maximum (GM) of the shaded PV array. The effectiveness of the proposed NPBVI MPPT is validated through numerous experiments that were carried out using a hardware prototype with a 150 W power rating. For the experiments, a PV array consisting of 3 × 2 (Np × Ns) 20 W PV modules was utilized. The experiments showcase agreement that the proposed method successfully identified the GM region of a partially shaded PV array.
Differences of Pore Features in Marine Shales between Lower Cambrian and Lower Silurian Formations of Upper Yangtze Area, South China
Authors: Li Minghui , Li Mingliang , Huang Haiping , Gong Lei , Zheng Debao
Published: January 2022

Lower Cambrian shale and lower Silurian shale are both typical of oil-prone kerogen and siliceous composition, but different in thermal maturities. Porosity differences were determined in marine shales between the two shales. Measurements were utilized including organic geochemistry, XRD, scanning electron microscopy (SEM) and N2 gas adsorption. Pore volume (PV) of lower Silurian shale was approximately 1.5 times higher than that of lower Cambrian shale, and pore surface area (PSA) of lower Silurian shale was almost 2.5 times higher than that of lower Cambrian shale. Lower Cambrian shale and lower Silurian shale possess similar materials, but distinctive thermal degrees. Evolution mechanisms of different types of pores, especially organic matter (OM)-hosted pores, may trigger this different pore features. Pores of rigid framework are the residue of primary interparticle pores during the burial history. Pores associated with clay flakes can be preserved well adjacent to rigid grains or secondary minerals acting as rigid frameworks or grain supporters. Dissolved pores in both lower Cambrian shale and lower Silurian shale barely contribute to the total porosity and mean little to the permeability. Both excessive OM content and over thermal maturity are detrimental to development of OM-hosted pores. Rigid particles, clay flakes, and OM commonly co-exist within shale matrix. Rigid grains act as supporters, clay flakes confine ample space, and OM first migrates into and provides secondary OM-hosted pores. In this condition, pores can be preserved owing to associating matrix with good mechanic and chemical stability. The significant differences of structural settings result into various hydrocarbon explosion efficiency and different pressure circumstance, which consequently leads to the different pore features between the two shales. For lower Cambrian shale, overpressure circumstance diminish if hydrocarbon expels outside of the shale system, and OM-hosted pores destroy through compaction. Sustaining overpressure and abundant residue hydrocarbon (migrated OM) make positive contributions to the pore properties, in terms of numbers, diameters and connectivity of the lower Silurian shale samples.
Prediction of Gas Concentration Based on LSTM-LightGBM Variable Weight Combination Model
Authors: Wang Xiangqian , Xu Ningke , Meng Xiangrui , Chang Haoqian
Published: January 2022

Gas accidents threaten the safety of underground coal mining, which are always accompanied by abnormal gas concentration trend. The purpose of this paper is to improve the prediction accuracy of gas concentration so as to prevent gas accidents and improve the level of coal mine safety management. Combining the LSTM model with the LightGBM model, the LSTM-LightGBM model is proposed with variable weight combination method based on residual assignment, which considers not only the time subsequence feature of data, but also the nonlinear characteristics of data. During the data preprocessing, the optimal parameters of gas concentration prediction are determined through the analysis of the Pearson correlation coefficients of different sensor data. The experimental results demonstrate that the mean absolute errors of LSTM-LighGBM, LSTM and LightGBM are 1.94%, 2.19% and 2.77%, respectively. The accuracy of LSTM-LightGBM variable weight combination model is better than that of the two above models, respectively. In this way, this study provides a novel idea and method for gas accident prevention based on gas concentration prediction.
Simulation Study of Solidification in the Shell-And-Tube Energy Storage System with a Novel Dual-PCM Configuration
Authors: Mozafari Moslem , Lee Ann , Cheng Shaokoon
Published: January 2022

This study proposes a novel dual-PCM configuration with outstanding solidification response in a horizontal shell-and-tube energy storage system. To demonstrate that the proposed PCM configuration is superior in its thermal responses, results from a range of numerical simulations are presented and compared between different configurations of dual-PCM. As the melting/solidus point is a crucial factor for the solidification rate, dual PCMs are chosen such that the average of their melting point is equal to the melting point of the single-PCM in the reference case. Additionally, equal-area sectors are considered for all cases to ensure the same quantities of PCMs are compared. The temporal liquid fraction and temperature contours reveal that solidification is delayed in the upper half of the system due to strong natural convection motions. Therefore, a dual-PCM configuration is offered to improve the solidification rate in this region and accelerate the full solidification process. Results show that placing a PCM with a lower solidus point in the lower half or an annulus-shaped zone around the cold tube can save the full recovery time up to 8.51% and 9.36%, respectively. The integration of these two strategies results in a novel and optimum design that saves the solidification time up to 15.09%.
A Multi Domain Modeling Approach for the CFD Simulation of Multi-Stage Gearboxes
Authors: Mastrone Marco Nicola , Concli Franco
Published: January 2022

The application of Computer-Aided Engineering (CAE) tools in mechanical design has consistently increased over the last decades. The benefits introduced by virtual models in terms of time and cost reductions are the main drivers for their exploitation in industry as well as for research purposes in academia. In this regard, Computational Fluid Dynamics (CFD) can be exploited to study lubrication and efficiency of gears. However, the mesh handling complexities deriving from the boundary motion is still a concern for its application to multi-stage gearboxes. In this work, an innovative multi domain partitioning method for the simulation of a two-stage industrial speed reducer is presented. The implemented solution foresees the combination of two remeshing strategies, namely GRA (Global Remeshing Approach) and GRAMC (GRA with Mesh Clustering), and resulted in a computationally effective performance. The results were compared with experimental data obtained with measurements on the real system, providing a good agreement in the power losses prediction. Considering the complexity of obtaining such results experimentally, the proposed numerical algorithm can offer substantial benefits for an estimation of the transmissions’ efficiency in various operating conditions. The numerical model was built in the open-source environment OpenFOAM®.
Energy Analysis of an Industrial Nozzle with Variable Outlet Conditions during Compressible and Transient Airflow
Authors: Wołosz Krzysztof J.
Published: January 2022

The nozzle which is applied in industrial pneumatic pulsators is studied. It is a part of the system for unclogging the drains and outlets of silos and hoppers for loose materials. The nozzle is required to achieve the lowest level of energy losses while directing the airflow, which impacts the loose material bed. The energy rate transferred into the bed depends on the temperature and pressure differences between the inlet and outlet of the nozzle. In this study, the available energy is determined assuming compressible and transient airflow through the nozzle, which is a part of the industrial pneumatic pulsator. Numerical simulations are performed using the OpenFOAM CFD toolbox. Energy analysis is carried out by using Reynolds Transport Theorem for specific energy for the variable temperature inside the silo on the basis of CFD results. In fact, the air parameters at the outlet of the nozzle are the ones inside the silo. The study showed that the design of the nozzle is not very sufficient from an energetic point of view.
Evaluation of the Program Subsidizing Prosumer Photovoltaic Sources in Poland
Authors: Zdonek Iwona , Tokarski Stanisław , Mularczyk Anna , Turek Marian
Published: January 2022

This article attempts to evaluate the My Electricity program concerning increasing renewable energy production in photovoltaic (PV) prosumer sources (PV micro-installations) in Poland. The assessment is made from the perspective of beneficiaries, business, and local community. One may also find an answer to the question of how this program should be modified so that it continues to support the development of PV systems in Poland. Moreover, how Poles assess the PV technology, in terms of the safety of its users and its impact on the environment, is studied. For this purpose, there was exploratory, qualitative, and quantitative research conducted. Twelve case studies were used as well as online questionnaires conducted on prosumers who used the My Electricity program to install PV micro-installations (57 respondents). By means of interviews, there was a confrontation of their point of view with the opinions of seven skeptics of such installations. Moreover, five experts from the energy industry and politicians involved in the transformation of the energy system were interviewed in order to balance the enthusiastic opinions of prosumers and the skeptical views of objectors to home PV systems. The results of our research indicate that the program is rated very well by enthusiasts of PV systems, although they emphasize the high investment costs and the lack of solutions supporting energy storage. Experts point out that the power grid in Poland is not prepared for such an immediate increase in prosumer PV systems, and they suggest more care in solving this problem.
Influence of Coil Current and Oil Film Thickness on Hopf Bifurcation of MLDSB
Authors: Zhao Jianhua , Zhang Hanwen , Chen Jianlin , Wu Xiaochen , Wang Yongqiang , Gao Dianrong , Liang Yingna
Published: January 2022

Magnetic-liquid double-suspension bearing (MLDSB) is composed of an electromagnetic supporting system and a hydrostatic supporting system. Due to its greater supporting capacity and stiffness, it is appropriate for middle-speed applications, overloading, and frequent starting. However, because it contains two sets of systems, its structure and rotor support system are more complex. It contains strong nonlinear links. When the parameters of the system change, the bearing rotor may feature Hopf bifurcation, resulting in system flutter and reducing the operational stability of the magnetic fluid double-suspension bearing rotor, which has become one of the key problems restricting its development and application. As key parameters of MLDSB, the coil current and oil film thickness exert a major impact on Hopf bifurcation. Therefore, the mathematical model of MLDSB is established in this paper, and the border and direction of Hopf bifurcation, period, and amplitude of limit cycle are analyzed. The calculation, simulation, and experimental results show that when the coil current and oil film thickness of the bearing system are greater than the boundary value of the Hopf bifurcation, Hopf bifurcation will occur, resulting in the vibration of the bearing rotor and affecting the stability of the system. In addition, when analyzing the combined effects of coil current and oil film thickness on the Hopf bifurcation of the system, it was found that the boundary value of Hopf bifurcation in the system is reduced compared with when it is are affected solely due to the coupling of the two parameters. The period, amplitude and vibration speed of limit cycle increase with increases in the coil current and oil film thickness. Hopf bifurcation experiment was conducted on MLDSB testing system. The results show that Hopf bifurcation does not occur when i0 < 0.5 A, the bearing rotor operates stably in the balanced position, i0 > 1.0 A, Hopf bifurcation occurs in the system, and the bearing rotor vibrates with equal amplitude, which reduces the stability of operation. The research in this paper can provide a theoretical reference for the Hopf bifurcation analysis of MLDSB.
Online Wind-Atlas Databases and GIS Tool Integration for Wind Resource Assessment: A Spanish Case Study
Authors: Sánchez-del Rey Agustín , Gil-García Isabel Cristina , García-Cascales María Socorro , Molina-García Ángel
Published: January 2022

Renewable energy sources are becoming increasingly integrated into the electricity-generation sector, being eco-friendly solutions, decreasing global warming, and improving the energy transition process. Among the different renewables, wind energy is considered a mature, clean, renewable, and inexhaustible technology as well, becoming one of the main resources in a sustainable framework. Aiming to evaluate the wind resource, scientific contributions have mostly presented a common basis: historical data campaigns of the wind resource mainly considering wind speed—including the module, direction, standard deviation, etc. However, online wind-atlas databases are becoming tools widely used for both wind-resource assessment and optimal wind-power locations. Under this framework, this study analyzed and compared such online wind data sources and their integration with GIS tools for optimal wind-resource-assessment purposes. The proposed methodology identified the corresponding wind-atlas databases directly on their websites and indirectly through the wind data used in relevant contributions about the optimal location of wind sites. Our contribution to the scientific community is thus the review and comparison of these atlas databases for reducing the barrier to access wind data—including GIS-tool-integration analysis. The limitations raised by civil societies, particularly regarding environmental and bird concerns, were not included in this study. Nevertheless, the authors are aware of these concerns and limitations. A Spanish case study was also included in this work, comparing both estimated and collected wind-atlas databases in terms of wind-resource assessment.
Numerical Study of Baroclinic Acoustic Streaming Phenomenon for Various Flow Parameters
Authors: Baran Błażej , Machaj Krystian , Malecha Ziemowit , Tomczuk Krzysztof
Published: January 2022

The article presents a numerical study of the large-amplitude, acoustically-driven streaming flow for different frequencies of the acoustic wave and different temperature gradients between hot and cold surfaces. The geometries studied were mainly two-dimensional rectangular resonators of different lengths, but also one three-dimensional rectangular resonator and one long and narrow channel, representative of a typical U-shaped resistance thermometer. The applied numerical model was based on the Navier–Stokes compressible equations, the ideal gas model, and finite volume discretization. The oscillating wall of the considered geometries was modeled as a dynamically moving boundary of the numerical mesh. The length of the resonators was adjusted to one period of the acoustic wave. The research confirmed that baroclinic acoustic streaming flow was largely independent of frequency, and its intensity increased with the temperature gradient between the hot and cold surface. Interestingly, a slight maximum was observed for some oscillation frequencies. In the case of the long and narrow channel, acoustic streaming manifested itself as a long row of counter-rotating vortices that varied slightly along the channel. 3D calculations showed that a three-dimensional pair of streaming vortices had formed in the resonator. Examination of the flow in selected cross-sections showed that the intensity of streaming gradually decreased as it approached the side walls of the resonator creating a quasi-parabolic profile. The future development of the research will focus on fully 3D calculations and precise identification of the influence of the bounding walls on the streaming flow.
Simultaneous Detection of NH3 and NO2 by Modified Impedance Spectroscopy in Sensors Based on Carbon Nanotubes
Authors: Blecha Tomas , Smitka Vaclav , Bodnar Michal , Stulik Jiri
Published: January 2022

There are many gaseous substances that need to be monitored for possible damage to health or the environment. This requires many sensors. The solution to reducing the number of sensors is to use one sensor to detect several gaseous substances simultaneously. Efforts to simplify sensor systems thus lead to the use of a sensor with a suitable sensitive layer and to finding a suitable method of detecting individual gaseous substances within one sensor. The aim is to find a suitable method to detect various gaseous substances acting on the sensor. For this purpose, modified impedance spectroscopy in the high-frequency range is applied, where the scattering parameters of the sensor based on carbon nanotubes are measured under the action of NO2 and NH3 gases. For this method of detection of gaseous substances, a suitable sensor platform structure was designed to enable the measurement of the electrical properties of the sensor in the GHz range. Based on the obtained results, it is possible to use one sensor to detect different types of gaseous substances.
Effect of the Intercalation and Dispersion of Organoclays on Energy Demand in the Extrusion of Recycled HDPE/PP Nanocomposites
Authors: Rigail-Cedeño Andres , Vera-Sorroche Javier , García-Mejía Gladys , Intriago Raul
Published: January 2022

Few studies have drawn on any systematic research into the energy demand to produce polymer-based nanocomposites. Regarding the problem, it is well-known that single screw extrusion is an energy-intensive process, so the incorporation of energy meters must be considered to examine the energy efficiency of the process. In this study, the effect of a nanoclay addition on the energy demand of the extrusion process was examined by extruding recycled high-density polyethylene (rHDPE) and recycled polypropylene (rPP) with a gradual compression screw with both dispersive and distributive mixers. The rHDPE/rPP was modified by adding commercial organoclay (OMMT) (3 wt%) and olefin block copolymer (OBC) (5 wt%) as compatibilizers. The energy consumption was measured on the total energy of the extruder machine. Mass throughput (MT) and specific energy consumption (SEC) were obtained at different screw speeds (10, 20, 30, 40, 50 RPM). The SEC of OMMT and OMMT/OBC nanocomposites was 25–50% lower than rHDPE/rPP, especially at higher throughputs. X-ray diffraction (XRD) and scanning electron microscope (SEM) illustrated the degree of intercalation and dispersion of the organoclay at different screw speeds. Better organoclay intercalation and dispersion were found at lower temperatures. Rheological curves showed a decrease in the viscosity at extrusion rates of nanocomposite mixtures. Melt temperature measured at die exit was reduced in the presence of organoclay over the screw speeds studied. This work suggests that the processing of rHDPE/rPP based nanocomposites can result in minor costs when processing conditions are carefully selected.
Aerodynamics and Complicated Heat Transfer with the Mixed Motion of Air in the Flat Duct of a High-Temperature Heat Exchanger
Authors: Basok Borys , Kremnev Vyacheslav , Pavlenko Anatoliy , Timoshchenko Andriy
Published: January 2022

The purpose of the research is to study the aerodynamics and heat transfer in the duct of a high-temperature recuperation system. The object of the research is a flat duct with a thickness-to-height ratio a:b = 1:10, length c = 400·a with one-sided heat input to the duct surface, complicated heat transfer and mixed air movement in the duct. The objectives of the research are to determine: (a) average temperatures on the duct surfaces; (b) air temperature distribution along the length of the duct; (c) local and average integral temperature values along the length of the duct; (d) local and average integral heat flow densities on the duct surfaces; (e) local and average integral heat exchange coefficients and Nusselt numbers on the duct surfaces; and (f) pressure distribution along the length and total pressure drop in the duct. The research method is based on conducting a mathematical numerical experiment in a stationary three-dimensional Cartesian formulation and physical modeling of processes on a prototype. It is established that the dominant heat transfer between the duct walls and the air is a complicated convective heat transfer, in which forced convection is affected by free convection. There is a 1.5–2.0-fold difference in the values of the heat flow density on the hot and non-heated surfaces of the duct. Generalizing dependences of Nusselt numbers, temperature pressures and friction resistance coefficients as functions of a dimensionless coordinate are obtained.
EU R&D Funding for Electricity Grid Technologies and the Energy Transition: Centralised versus Decentralised Transition Pathways
Authors: Klitkou Antje , Fevolden Arne Martin , Andersen Allan Dahl
Published: January 2022

In the acceleration phase transitions often increase in depth and scope, and thereby create knock-on effects for wider system structures. In the renewable energy transition, for example, higher shares of intermittent renewable energy sources call for new grid technologies to increase flexible grid operation. At the same time, there are different ways of achieving renewable energy transitions and providing flexibility. In Europe, important tensions exist over how centralised or decentralised a renewable energy electricity system should be. This paper explores to what extent and how European framework programmes for research and development have addressed and supported innovation in transmission grid (centralised system) and distribution grid (decentralised) technologies. We analyse European R&D projects that studied electricity grid planning, development and innovation over 2002–2020. We apply social network analysis of the collaboration partners in these projects, and analyse the calls for proposals issued by three European Framework Programmes: FP6, FP7 and Horizon 2020. The framework programmes have addressed energy-related issues, but the priorities have changed over time, reflecting the ongoing energy transition. We ask if the importance of transmission grid vs. distribution grid has changed over time, and if and how the collaboration patterns have changed.
Development of Generalized Distribution Utility Index in Consumer-Driven Logistics
Authors: Galkin Andrii , Schlosser Tibor , Khvesyk Yuliia , Kuzkin Olexiy , Klapkiv Yuriy , Balint Gabriel
Published: January 2022

In the current conditions of sharp change in demand and instability of markets, there is a need to develop a method and evaluation criterion that would meet the sustainable scenario of a supplying goods system including the consumer-driven concept. The analysis of goods distribution methods showed that to assess the integrated efficiency between the supply system and its end-consumers, it is advisable to apply integrated criterion efficiency—generalized distribution utility. The developed indicator takes into account the profit of the distribution channel (or its participants) and the generalized costs of end users during shopping activity. Based on the proposed indicator, the feasibility of using vehicle capacity is substantiated, which provides the maximum generalized distribution costs value and corresponds to the optimal sustainable distribution in consumer-driven logistics.
On-Line Monitoring of Biological Parameters in Microalgal Bioprocesses Using Optical Methods
Authors: Havlik Ivo , Beutel Sascha , Scheper Thomas , Reardon Kenneth F.
Published: January 2022

Microalgae are promising sources of fuels and other chemicals. To operate microalgal cultivations efficiently, process control based on monitoring of process variables is needed. On-line sensing has important advantages over off-line and other analytical and sensing methods in minimizing the measurement delay. Consequently, on-line, in-situ sensors are preferred. In this respect, optical sensors occupy a central position since they are versatile and readily implemented in an on-line format. In biotechnological processes, measurements are performed in three phases (gaseous, liquid and solid (biomass)), and monitored process variables can be classified as physical, chemical and biological. On-line sensing technologies that rely on standard industrial sensors employed in chemical processes are already well-established for monitoring the physical and chemical environment of an algal cultivation. In contrast, on-line sensors for the process variables of the biological phase, whether biomass, intracellular or extracellular products, or the physiological state of living cells, are at an earlier developmental stage and are the focus of this review. On-line monitoring of biological process variables is much more difficult and sometimes impossible and must rely on indirect measurement and extensive data processing. In contrast to other recent reviews, this review concentrates on current methods and technologies for monitoring of biological parameters in microalgal cultivations that are suitable for the on-line and in-situ implementation. These parameters include cell concentration, chlorophyll content, irradiance, and lipid and pigment concentration and are measured using NMR, IR spectrophotometry, dielectric scattering, and multispectral methods. An important part of the review is the computer-aided monitoring of microalgal cultivations in the form of software sensors, the use of multi-parameter measurements in mathematical process models, fuzzy logic and artificial neural networks. In the future, software sensors will play an increasing role in the real-time estimation of biological variables because of their flexibility and extendibility.
Using the Data of Geocryological Monitoring and Geocryological Forecast for Risk Assessment and Adaptation to Climate Change
Authors: Osipov Victor , Aksyutin Oleg , Sergeev Dmitrii , Tipenko Gennadii , Ishkov Alexandre
Published: January 2022

Permafrost monitoring should be organized in different ways within undisturbed landscapes and in areas with technogenic impacts. The state and dynamics of permafrost are described by special indicators. It helps to characterize seasonal and long-term tendencies and link them with permafrost hazards estimation. The risk is determined by the hazard probability and the vulnerability of infrastructure elements. The hazard does not have integral indicators, but is determined by separate spatial and temporal characteristics. The spatial characteristics include the ground’s physical and cryolithological features that are linked with the history of the permafrost. The temporal characteristics are associated with the future evolution of the climate and anthropogenic pressures. The geocryological monitoring content and geocryological forecasting are interdependent and should be implemented together. The adaptation recommendations are based on the analytical algorithms and use the results of permafrost monitoring and permafrost state forecasting. The development of an adaptation program is a recognition of the company’s responsibility for the sustainable development of resource management territories. Risk management uses the methods of the flexible ground temperature regime management.
The Vision of Self-Management in Cognitive Organic Power Distribution Systems
Authors: Loeser Inga , Braun Martin , Gruhl Christian , Menke Jan-Hendrik , Sick Bernhard , Tomforde Sven
Published: January 2022

Due to the ongoing trend towards a decarbonisation of energy use, the power system is expected to become the backbone of all energy sectors and thus the fundamental critical infrastructure. High penetration with distributed energy resources demands the coordination of a large number of prosumers, partly controlled by home energy management systems (HEMS), to be designed in such a way that the power system’s operational limits are not violated. On the grid level, distribution management systems (DMS) seek to keep the power system in the normal operational state. On the prosumer level, distributed HEMS optimise the internal power flows by setpoint specification of batteries, photovoltaic generators, or flexible loads. The vision of the ODiS (Organic Distribution System) initiative is to develop an architecture to operate a distribution grid reliably, with high resiliency, and fully autonomously by developing “organic” HEMS and DMS which possess multiple self-x capabilities, collectively referred to as self-management. Thus, ODiS seeks answers to the following question: How can we create the most appropriate models, techniques, and algorithms to develop novel kinds of self-configuring, self-organising, self-healing, and self-optimising DMS that are integrally coupled with the distributed HEMS? In this concept paper, the vision of ODiS is presented in detail based on a thorough review of the state of the art.
Numerical Study of Thermochemistry and Trace Element Behavior during the Co-Combustion of Coal and Sludge in Boiler
Authors: Liang Di , Li Yimin , Zhou Zhongning
Published: January 2022

Sludge is one of the main pollutants from sewage treatment and contains a high content of water and organic matter. The co-combustion of sludge and coal can bring about the energy conversion of sludge. However, the high moisture content in sludge and the inorganic pollutants generated by co-combustion have adverse effects on combustion and the environment. In this work, through experimentation, it was demonstrated that co-combustion does not release obvious toxic elements or create an environmental hazard. On the basis of the TG/DTG curves, the ignition points of sludge and coal and the temperature of each group were obtained, which provided boundary conditions for a numerical simulation. Co-combustion with various mixing ratios and moisture contents was studied via the numerical simulation of a 330 MW boiler. The numerical results show that a high mixing ratio reduced the boiler temperature and created more moisture and fuel NOx. When the mixing ratio reached 40%, the boiler temperature became less than the combustion temperature. Sludge drying improved the internal temperature of the boiler, but it created thermal NOx. When the moisture content decreased to 40%, the temperature in the boiler rose, which improved combustion.
An Adaptive Building Skin Concept Resulting from a New Bioinspiration Process: Design, Prototyping, and Characterization
Authors: Hubert Tessa , Dugué Antoine , Vogt Wu Tingting , Aujard Fabienne , Bruneau Denis
Published: January 2022

Building envelopes can manage light, heat gains or losses, and ventilation and, as such, play a key role in the overall building performance. Research has been focusing on increasing their efficiency by proposing dynamic and adaptive systems, meaning that they evolve to best meet the internal and external varying conditions. Living organisms are relevant examples of adaptability as they have evolved, facing extreme conditions while maintaining stable internal conditions for survival. From a framework based on the inspiration of living envelopes such as animal constructions or biological skins, the concept of an adaptive envelope inspired by the Morpho butterfly was proposed. The system can manage heat, air, and light transfers going through the building and includes adaptive elements with absorption coefficients varying with temperature. This paper presents the developed framework that led to the final concept as well as the concept implementation and assessment. A prototype for heat and light management was built and integrated into a test bench. Measurements were performed to provide a first assessment of the system. In parallel, geometrical parametric models were created to compare multiple configurations in regards to indicators such as air, light, or heat transfers. One of the models provided light projections on the system that were compared with measurements and validated as suitable inputs in grey-box models for the system characterization.
Enhancing Efficiency of Industrial Centrifugal Fans Using Blade Adjustment Mechanism
Authors: Moczko Przemyslaw , Odyjas Piotr , Pietrusiak Damian , Więckowski Jędrzej , Scholz Peter , Dix Martin , Osiecki Tomasz , Timmel Tristan , Kroll Lothar
Published: January 2022

The paper presents research on increasing the efficiency of industrial centrifugal fans, which are the third highest energy-consuming group of devices. This problem is related to the frequent incompatibility of the fan characteristics with the flow conditions of the installation in which they are operated, which lowers efficiency and increases energy consumption. By ensuring high efficiency of these devices, it is possible to significantly reduce the operating costs of such industrial equipment. For this purpose, a unique concept of regulating the flow parameters of centrifugal fans was developed. The scientific basis of this idea is that a relatively small change in the impeller diameter of the fan significantly affects the flow rate and the pressure rise of the fan. Therefore, the idea uses variable length of the impeller blades by dividing them into a fixed and a movable part. It enables adjustment of the length of the blades, which allows extension of the range of effective and efficient operating parameters. On this basis, several technical solutions of the regulation system were developed, which were then tested using simulation and analytical methods. Two material options for the moving part of the blade have also been developed, one made of metallic materials (high-strength steel and aluminum) and the other made of composite materials. The research showed a significant influence of the mass of the movable part of the blade on the load of the control system. Therefore, ultra-light material variants were used for the impeller blades. The flow simulation tests of the new method of adjusting the fan flow parameters confirmed the effectiveness of this solution. As a result, a wider range of highly efficient centrifugal fans equipped with such a control system was obtained.
Study of Induction Motor Inter-Turn Fault Part I: Development of Fault Models with Distorted Flux Representation
Authors: Im Seong-Hwan , Gu Bon-Gwan
Published: January 2022

An inter-turn fault (ITF) is one of the most frequent induction motor faults; thus, many previous works have studied its model and diagnosis. However, previous works, simplifying the specific distorted flux distribution by the ITF, presented induction motor fault models and focused on the fault signal analysis for diagnoses. Consequently, these results are only adequate for the pretested motor and sensitive to fault signal distortion. This paper presents an induction motor ITF model in the stationary DQ frame, for a model-based diagnosis. Furthermore, to describe the distorted flux distribution along the air gap by the ITF, the rotor flux linkages are described in the independent DQ frame of every pole, and the mutual flux linkages among the rotor, stator, and ITF windings are specifically modeled. Hence, the proposed full model has many current states and mutual inductances to describe the high pole number motor. A simplified model is also proposed for easier usage in the diagnosis, with light ITF to overcome this complexity. Finally, simulation and experiments are performed to verify the presented induction motor ITF fault models.