bluuebunny/crossref_metadata_2025 huggingface dataset:
Study, Development and Prototyping of a Novel Mild Hybrid Power Train for a City Car: Design of the Turbocharger
Authors: Capata Roberto , Sciubba Enrico
Published: December 2020

Within a large, state-funded, Italian National Project aimed to test the feasibility of an on-the-road prototype of a mild hybrid city vehicle, one of the tasks was to conceive, design and implement an innovative turbocharger that would allow for some energy recovery. The selected vehicle is propelled by a 3-cylinder, 998 cc turbocharged engine (the 66 kW Mitsubishi-Smart W451). The idea is to implement two types of energy recovery: one via the new turbocharger and one through a standard braking energy recovery (also known as KERS). The study of the former is the object of this paper. The proposed turbocharger configuration consists of mechanically separated, electrically coupled compressor and turbine, possibly mounting only slightly modified commercial equipment to reduce construction costs. This paper reports the results of the calculation of the behavior of the new turbocharging group across the entire engine operating range and describes the preliminary design of the unit. An accurate simulation of a mixed (urban and extra-urban) driving mission demonstrates that a net saving of about 5.6% can be attained by the installation of the novel turbocharger unit.
Development of a Novel Concrete Curing Method Using Induction Heating System
Authors: Ahn Chi-Hyung , Lee Jinbok , Kim Dong-Jin , Shin Hyun-Oh
Published: December 2020

This study aimed to develop an accelerated concrete curing method based on induction heating (IH) technology. The proposed curing method provides improved heating efficiency and safety since it directly heats only the metallic forms in a non-contacting manner. It also has the advantage of being capable of heating the concrete according to a desirable heating scenario. The effects of several parameters on its performance were evaluated using a finite element method (FEM)-based thermal analysis and heating performance tests. The FEM analysis revealed the steel form to be appropriate for the IH system. The analysis also revealed that equally spaced three-turn coils yielded increased temperature uniformity in the steel form, which was verified by results of the steel form heating experiments. Furthermore, the minimum temperature generated in the form was sufficient for concrete curing. The efficiency of the use of IH for concrete curing and the effects of curing parameters were further investigated through compression tests after applications of various curing methods and by examining the temperature distributions during curing. The test results revealed early strength development even under water freezing conditions. This demonstrated the effectiveness of IH for concrete curing in cold weather. However, the efficiency decreased when the cross-sectional dimension of the specimen increased. The test results also verified that the maximum temperature and duration of induction heat curing affect the early age strength of concrete.
Predicting Student Performance Using Data Mining and Learning Analytics Techniques: A Systematic Literature Review
Authors: Namoun Abdallah , Alshanqiti Abdullah
Published: December 2020

The prediction of student academic performance has drawn considerable attention in education. However, although the learning outcomes are believed to improve learning and teaching, prognosticating the attainment of student outcomes remains underexplored. A decade of research work conducted between 2010 and November 2020 was surveyed to present a fundamental understanding of the intelligent techniques used for the prediction of student performance, where academic success is strictly measured using student learning outcomes. The electronic bibliographic databases searched include ACM, IEEE Xplore, Google Scholar, Science Direct, Scopus, Springer, and Web of Science. Eventually, we synthesized and analyzed a total of 62 relevant papers with a focus on three perspectives, (1) the forms in which the learning outcomes are predicted, (2) the predictive analytics models developed to forecast student learning, and (3) the dominant factors impacting student outcomes. The best practices for conducting systematic literature reviews, e.g., PICO and PRISMA, were applied to synthesize and report the main results. The attainment of learning outcomes was measured mainly as performance class standings (i.e., ranks) and achievement scores (i.e., grades). Regression and supervised machine learning models were frequently employed to classify student performance. Finally, student online learning activities, term assessment grades, and student academic emotions were the most evident predictors of learning outcomes. We conclude the survey by highlighting some major research challenges and suggesting a summary of significant recommendations to motivate future works in this field.
Theoretical Aspects for Calculating the Mobilized Load during Suspension Training through a Mobile Application
Authors: López-Moranchel Ignacio , Alegre Luis M. , Maurelos-Castell Patricia , Picó Pérez Vicent , Ara Ignacio
Published: December 2020

Introduction: This study describes the theoretical foundations of the development of an equation that allows for the estimation of the mobilized load when training with suspension devices (type TRX®) and presents a mobile application as a means for its use. Methods: Systems of equations are proposed of which the terms depend on the angulation of the device with respect to the vertical (angle α), the relationship between the height of grip, the height of the center of mass and the weight of the subject, which are recorded from a photo. Results: Based on the photo and the subject’s standing height, the application allows the user to measure the angle α, providing the values of applied force (in N) and mobilized load in relation to the percentage of body mass, applying the calculations described in our equations. The equation also provides the estimated value of the load mobilized during a push up on the floor (68% of the subject’s body mass) and the equation for the calculation of the mobilized load when the suspension device is fixed to the feet. Conclusions: It is possible to use equations to estimate the load mobilized in each repetition during training using suspension devices and to implement this algorithm in a mobile application.
Adaptive Control for a Biological Process under Input Saturation and Unknown Control Gain via Dead Zone Lyapunov Functions
Authors: Rincón Alejandro , Hoyos Fredy E. , Candelo-Becerra John E.
Published: December 2020

In this work, substrate control of a biological process with unknown varying control gain, input saturation, and uncertain reaction rate is addressed. A novel adaptive controller is proposed, which tackles the combined effect of input saturation and unknown varying control gain with unknown upper and lower bounds. The design is based on dead zone radially unbounded Lyapunov-like functions, with the state backstepping as control framework. The convergence of the modified tracking error and the boundedness of the updated parameters are ensured by means of the Barbalat’s lemma. As the first distinctive feature, a new second-order auxiliary system is proposed that tackles the effect of saturated input and the unknown varying control gain with unknown upper and lower bounds. As the second distinctive feature, the modified tracking error converges to a compact set whose width is user-defined, so that it does not depend on bounds of either external disturbances, model terms, or model coefficients. The convergence region of the current tracking error is determined for the closed loop system subject to the formulated controller and the proposed auxiliary system. Finally, numerical simulation illustrates the performance of the proposed controller.
Residual Stress Relaxation of DRWDs in OSDs under Constant/Variable Amplitude Cyclic Loading
Authors: Zhong Wen , Ding Youliang , Song Yongsheng , Geng Fangfang , Wang Zhiwen
Published: December 2020

An orthotropic steel deck (OSD) has a complicated structure, and its fatigue life is mainly determined by various welding details. Fatigue assessment of deck-to-rib welding details (DRWDs) under long-term train loads is an important concern for engineers. Properly assessing the initial residual stress and the mechanism of stress relaxation in DRWDs under long-term external loading is a prerequisite for predicting the fatigue damage and service life of OSDs. In this paper, a finite element analysis method is proposed to calculate the residual stress relaxation in DRWDs of OSDs under constant/variable amplitude cyclic loading. First, experiments on full-size OSD specimens were carried out using the hole drilling strain-gauge method, and the multi-axial distribution characteristics of residual stress on the sub-surface of the deck were obtained. On this basis, a refined residual stress analysis model of DRWDs using thermal-structural sequence coupling analysis and life and death unit technology is established, and the accuracy of the model is verified by the test data. Second, a coupling stress analysis model that considers the welding residual stress and mechanical stress using cyclic plastic constitutive model is established. The combined influence of number of cycles, stress amplitude, and stress ratio on multi-axial residual stress relaxation effect under constant/variable amplitude cyclic loading is investigated. Finally, a release formula of welding residual stress relaxation coefficient is proposed based on the external loading stress amplitude, stress ratio, and material yield stress. The results show that (1) with the increase in the number of loading cycles, the stress decreases until it is stabilized, while the global distribution of welding residual stress remains unchanged. Most of the welding residual stress release (about 95%) occurs in the first cycle; (2) the residual stress relaxation decreases with the increase in stress amplitude and increases linearly with the stress ratio; (3) the residual stress release is controlled by the maximum amplitude stress in the variable amplitude cyclic loading. After the residual stress is released, the stress will not continue to be released if the DRWDs have the same or smaller amplitude loading.
Electrospun Fiber Scaffolds for Engineering Glial Cell Behavior to Promote Neural Regeneration
Authors: Puhl Devan L. , Funnell Jessica L. , Nelson Derek W. , Gottipati Manoj K. , Gilbert Ryan J.
Published: December 2020

Electrospinning is a fabrication technique used to produce nano- or micro- diameter fibers to generate biocompatible, biodegradable scaffolds for tissue engineering applications. Electrospun fiber scaffolds are advantageous for neural regeneration because they mimic the structure of the nervous system extracellular matrix and provide contact guidance for regenerating axons. Glia are non-neuronal regulatory cells that maintain homeostasis in the healthy nervous system and regulate regeneration in the injured nervous system. Electrospun fiber scaffolds offer a wide range of characteristics, such as fiber alignment, diameter, surface nanotopography, and surface chemistry that can be engineered to achieve a desired glial cell response to injury. Further, electrospun fibers can be loaded with drugs, nucleic acids, or proteins to provide the local, sustained release of such therapeutics to alter glial cell phenotype to better support regeneration. This review provides the first comprehensive overview of how electrospun fiber alignment, diameter, surface nanotopography, surface functionalization, and therapeutic delivery affect Schwann cells in the peripheral nervous system and astrocytes, oligodendrocytes, and microglia in the central nervous system both in vitro and in vivo. The information presented can be used to design and optimize electrospun fiber scaffolds to target glial cell response to mitigate nervous system injury and improve regeneration.
Cytokinin N-glucosides: Occurrence, Metabolism and Biological Activities in Plants
Authors: Pokorná Eva , Hluska Tomáš , Galuszka Petr , Hallmark H. Tucker , Dobrev Petre I. , Záveská Drábková Lenka , Filipi Tomáš , Holubová Katarína , Plíhal Ondřej , Rashotte Aaron M. , Filepová Roberta , Malbeck Jiří , Novák Ondřej , Spíchal Lukáš , Brzobohatý Břetislav , Mazura Pavel , Zahajská Lenka , Motyka Václav
Published: December 2020

Cytokinins (CKs) are a class of phytohormones affecting many aspects of plant growth and development. In the complex process of CK homeostasis in plants, N-glucosylation represents one of the essential metabolic pathways. Its products, CK N7- and N9-glucosides, have been largely overlooked in the past as irreversible and inactive CK products lacking any relevant physiological impact. In this work, we report a widespread distribution of CK N-glucosides across the plant kingdom proceeding from evolutionary older to younger plants with different proportions between N7- and N9-glucosides in the total CK pool. We show dramatic changes in their profiles as well as in expression levels of the UGT76C1 and UGT76C2 genes during Arabidopsis ontogenesis. We also demonstrate specific physiological effects of CK N-glucosides in CK bioassays including their antisenescent activities, inhibitory effects on root development, and activation of the CK signaling pathway visualized by the CK-responsive YFP reporter line, TCSv2::3XVENUS. Last but not least, we present the considerable impact of CK N7- and N9-glucosides on the expression of CK-related genes in maize and their stimulatory effects on CK oxidase/dehydrogenase activity in oats. Our findings revise the apparent irreversibility and inactivity of CK N7- and N9-glucosides and indicate their involvement in CK evolution while suggesting their unique function(s) in plants.
Gut Microbiome Composition Remains Stable in Individuals with Diabetes-Related Early to Late Stage Chronic Kidney Disease
Authors: Lecamwasam Ashani , Nelson Tiffanie M. , Rivera Leni , Ekinci Elif I. , Saffery Richard , Dwyer Karen M.
Published: December 2020

(1) Background: Individuals with diabetes and chronic kidney disease display gut dysbiosis when compared to healthy controls. However, it is unknown whether there is a change in dysbiosis across the stages of diabetic chronic kidney disease. We investigated a cross-sectional study of patients with early and late diabetes associated chronic kidney disease to identify possible microbial differences between these two groups and across each of the stages of diabetic chronic kidney disease. (2) Methods: This cross-sectional study recruited 95 adults. DNA extracted from collected stool samples were used for 16S rRNA sequencing to identify the bacterial community in the gut. (3) Results: The phylum Firmicutes was the most abundant and its mean relative abundance was similar in the early and late chronic kidney disease group, 45.99 ± 0.58% and 49.39 ± 0.55%, respectively. The mean relative abundance for family Bacteroidaceae, was also similar in the early and late group, 29.15 ± 2.02% and 29.16 ± 1.70%, respectively. The lower abundance of Prevotellaceae remained similar across both the early 3.87 ± 1.66% and late 3.36 ± 0.98% diabetic chronic kidney disease groups. (4) Conclusions: The data arising from our cohort of individuals with diabetes associated chronic kidney disease show a predominance of phyla Firmicutes and Bacteroidetes. The families Ruminococcaceae and Bacteroidaceae represent the highest abundance, while the beneficial Prevotellaceae family were reduced in abundance. The most interesting observation is that the relative abundance of these gut microbes does not change across the early and late stages of diabetic chronic kidney disease, suggesting that this is an early event in the development of diabetes associated chronic kidney disease. We hypothesise that the dysbiotic microbiome acquired during the early stages of diabetic chronic kidney disease remains relatively stable and is only one of many risk factors that influence progressive kidney dysfunction.
Effect of Dog-Assisted Therapy on Psychomotor Development of Children with Intellectual Disability
Authors: Wolan-Nieroda Andżelina , Dudziak Jadwiga , Drużbicki Mariusz , Pniak Bogumiła , Guzik Agnieszka
Published: December 2020

Background: Although dog-assisted therapy (DAT) has been used for years, there is still a scarcity of research findings confirming efficacy of the method. The current study was designed to assess effects of DAT on psychomotor development of children with mild intellectual disabilities. Material and method: The study involved 60 children with mild intellectual disabilities, aged 10–13 years, divided into a group participating in a 10-month DAT program, and the control group. Four tests were applied, i.e., finger identification, postural imitation, kinaesthesia, and Bourdon-Wiersma Dot Cancellation Test. The examinations were carried out before the start and at the end of the DAT, and at a two-month follow-up. Results: The results obtained by the DAT group in all the four tests, at all the three timepoints, were not the same (p < 0.001). No statistically significant differences were found in the measurement at the end of the therapy between the DAT group and the controls. On the other hand, the DAT group achieved significantly better scores (p = 0.001 and p = 0.001), compared to the control, in the follow-up measurements two months after the end of the therapy in postural imitation and finger identification tests. Conclusions: Some of the scores achieved by the children in the DAT group improved in the measurements performed over time. Two months after the therapy ended, the children in the DAT group presented greater gains in motor planning (postural imitation test) and in the sense of touch, attention, and concentration (finger identification test), compared to the control group. Although the measurement performed immediately after the therapy did not show significant differences between the DAT group and the controls, the examination carried out at the two-month follow-up identified long-term gains in the treatment group in the domain of motor planning (postural imitation test).
Determinants of Household-Level Coping Strategies and Recoveries from Riverine Flood Disasters: Empirical Evidence from the Right Bank of Teesta River, Bangladesh
Authors: Mondal Md. Sanaul Haque , Murayama Takehiko , Nishikizawa Shigeo
Published: December 2020

Although recurrent floods cause detrimental impact for the people living in riverine floodplains, households are taking up various risks management strategies to deal with them. This paper examined household’s post-disaster coping strategies to respond and recover from riverine floods in 2017. Data were collected through a questionnaire survey from 377 households from the right bank of Teesta River in Bangladesh. Households employed different coping strategies including borrowing money, assets disposal, consumption reduction, temporary migration, and grants from external sources, to cope with flood. Results from logistic regression models suggested that increasing severity of flood reduced households’ consumption. Exposed households were more likely to borrow money. Consumption reduction and temporary migration were mostly adopted by agricultural landless households. Income from nonfarm sources was found to be an important factor influencing household’s decisions on coping. Furthermore, households that recovered from the last flood disaster seek insurance through their own savings and available physical assets, highlighting the role of disaster preparedness in resilient recovery. This study calls for the policy intervention at the household-level to enhance the adaptive capacity of riverine households so that people at risk can cope better and recover from flood disaster using their resources.
Accurate Spectral Collocation Computation of High Order Eigenvalues for Singular Schrödinger Equations
Authors: Gheorghiu Călin-Ioan
Published: December 2020

We are concerned with the study of some classical spectral collocation methods, mainly Chebyshev and sinc as well as with the new software system Chebfun in computing high order eigenpairs of singular and regular Schrödinger eigenproblems. We want to highlight both the qualities as well as the shortcomings of these methods and evaluate them in conjunction with the usual ones. In order to resolve a boundary singularity, we use Chebfun with domain truncation. Although it is applicable with spectral collocation, a special technique to introduce boundary conditions as well as a coordinate transform, which maps an unbounded domain to a finite one, are the special ingredients. A challenging set of “hard”benchmark problems, for which usual numerical methods (f. d., f. e. m., shooting, etc.) fail, were analyzed. In order to separate “good”and “bad”eigenvalues, we have estimated the drift of the set of eigenvalues of interest with respect to the order of approximation and/or scaling of domain parameter. It automatically provides us with a measure of the error within which the eigenvalues are computed and a hint on numerical stability. We pay a particular attention to problems with almost multiple eigenvalues as well as to problems with a mixed spectrum.
Microangiopathy in Ocular Sarcoidosis Using Fluorescein Gonio and Fundus Angiography from Diagnostic and Therapeutic Aspects
Authors: Hamanaka Teruhiko , Akabane Noriko , Sakurai Tetsuro , Ikushima Soichiro , Kumasaka Toshio , Takemura Tamiko
Published: December 2020

In this retrospective study, we investigated vascular abnormalities in sarcoidosis using fluorescein gonioangiography (FGA) to detect angle neovascularization (ANV), fundus fluorescein angiography (FFA), and pathological specimens from the aspects of microangiopathy. In 57 sarcoidosis patients, clinical data was reviewed by dividing the cases into three groups (Group I: histologically diagnosed; Group II: positive bilateral hilar lymphadenopathy (BHL); Group III: negative BHL). The FFA, FGA, and pathological examination data in the autopsy eyes and trabeculectomy specimens were investigated. FGA and FFA detected ANV (91%) and nodule-associated abnormalities (87%), respectively. No intraocular pressure (IOP) elevation was observed after continuous topical betamethasone, except in the steroid responder group. Maximum IOP had significant correlation with nodules in the angle (p = 0.02696) and visual field defect (p = 0.0151). Granulomas adjacent to blood vessels, including the Schlemm’s canal, and thickening of the retinal blood vessel wall caused occlusion of those vessels. Photocoagulation was required for retinal tears (14%) and the retinal blood vessel occlusion (7%). Suppression of IOP elevation via continuous topical betamethasone may be important to avoid irreversible outflow-route changes and optic-nerve damage, and the concept of microangiopathy in ocular sarcoidosis may be important for understanding the proper treatment of serious complications.
Determining Causal Skeletons with Information Theory
Authors: Sigtermans David
Published: December 2020

Modeling a causal association as arising from a communication process between cause and effect, simplifies the discovery of causal skeletons. The communication channels enabling these communication processes, are fully characterized by stochastic tensors, and therefore allow us to use linear algebra. This tensor-based approach reduces the dimensionality of the data needed to test for conditional independence, e.g., for systems comprising three variables, pair-wise determined tensors suffice to infer the causal skeleton. The only thing needed is a minor extension to information theory, namely the concept of path information.
Single-Layer Line-Fed Broadband Microstrip Patch Antenna on Thin Substrates
Authors: Vincenti Gatti Roberto , Rossi Riccardo , Dionigi Marco
Published: December 2020

In this work, the issue of limited bandwidth typical of microstrip antennas realized on a single thin substrate is addressed. A simple yet effective design approach is proposed based on the combination of traditional single-resonance patch geometries. Two novel shaped microstrip patch antenna elements with an inset feed are presented. Despite being printed on a single-layer substrate with reduced thickness, both radiators are characterized by a broadband behavior. The antennas are prototyped with a low-cost and fast manufacturing process, and measured results validate the simulations. State-of-the-art performance is obtained when compared to the existing literature, with measured fractional bandwidths of 3.71% and 6.12% around 10 GHz on a 0.508-mm-thick Teflon-based substrate. The small feeding line width could be an appealing feature whenever such radiating elements are to be used in array configurations.
Ferroelectric Polarization Aided Low Voltage Operation of 3D NAND Flash Memories
Authors: Ham Ilsik , Jeong Youngseok , Baik Seung Jae , Kang Myounggon
Published: December 2020

In this paper, we proposed a novel structure enabling the low voltage operation of three-dimensional (3D) NAND flash memory. The proposed structure has a ferroelectric thin film just beneath the control gate, where the inserted ferroelectric material is assumed to have two stable polarization states. A voltage for ferroelectric polarization (VPF) that is lower than the program or erase voltage is used to toggle the polarization state of the ferroelectric thin film, whose impact on the channel potential profile is analyzed to optimize operation voltage reduction. The channel potential of select word line (WL), where the natural local self-boosting (NLSB) effect occurs, increases due to the polarization state. Model parameters for the ferroelectric thin film of 8 nm are fixed to 15 µC/cm2 for remanent polarization (Pr), 30 µC/cm2 for saturation polarization (Ps), and 2 MV/cm for coercive field (Ec). Within our simulation conditions, a program voltage (VPGM) reduction from 18 V to 14 V is obtained.
A Hybrid Prognostics Deep Learning Model for Remaining Useful Life Prediction
Authors: Xie Zhiyuan , Du Shichang , Lv Jun , Deng Yafei , Jia Shiyao
Published: December 2020

Remaining Useful Life (RUL) prediction is significant in indicating the health status of the sophisticated equipment, and it requires historical data because of its complexity. The number and complexity of such environmental parameters as vibration and temperature can cause non-linear states of data, making prediction tremendously difficult. Conventional machine learning models such as support vector machine (SVM), random forest, and back propagation neural network (BPNN), however, have limited capacity to predict accurately. In this paper, a two-phase deep-learning-model attention-convolutional forget-gate recurrent network (AM-ConvFGRNET) for RUL prediction is proposed. The first phase, forget-gate convolutional recurrent network (ConvFGRNET) is proposed based on a one-dimensional analog long short-term memory (LSTM), which removes all the gates except the forget gate and uses chrono-initialized biases. The second phase is the attention mechanism, which ensures the model to extract more specific features for generating an output, compensating the drawbacks of the FGRNET that it is a black box model and improving the interpretability. The performance and effectiveness of AM-ConvFGRNET for RUL prediction is validated by comparing it with other machine learning methods and deep learning methods on the Commercial Modular Aero-Propulsion System Simulation (C-MAPSS) dataset and a dataset of ball screw experiment.
Deep Neural Network Approach for Prediction of Heating Energy Consumption in Old Houses
Authors: Lee Sungjin , Cho Soo , Kim Seo-Hoon , Kim Jonghun , Chae Suyong , Jeong Hakgeun , Kim Taeyeon
Published: December 2020

Neural network models are data-driven and are effective for predicting and interpreting nonlinear or unexplainable physical phenomena. This study collected building information and heating energy consumption data from 16,158 old houses, selected key input variables that affect the heating energy consumption based on the collected datasets, and developed a deep neural network (DNN) model that showed the highest accuracy for the prediction of heating energy consumption in an old house. As a result, 11 key input variables were selected, and an optimal DNN model was developed. This optimal DNN model showed the highest prediction accuracy (R2 = 0.961) when the number of hidden layers was five and the number of neurons was 22. When the optimal DNN model was applied for the standard model of low-income detached houses, the prediction accuracy (Cv(RMSE)) of the optimal DNN model, compared to the EnergyPlus calculation result, was 8.74%, which satisfied the ASHRAE standard sufficiently.
Integration of PV into the Sarajevo Canton Energy System-Air Quality and Heating Challenges
Authors: Dedović Maja Muftić , Avdaković Samir , Mujezinović Adnan , Dautbašić Nedis
Published: December 2020

The use of renewable energy sources increases the energy self-sustainability of cities, enabling citizens to reduce energy costs, which results in an increase in their standard of living. However, solar energy penetration in Bosnia and Herzegovina, and its capital Sarajevo, is not in line with the possibilities. Furthermore, the Sarajevo Canton is extremely polluted during the winter months because of the use of unacceptable heating fuel. The aim of this paper is to introduce photovoltaic power systems use in heating electrification system. In this paper AQI is calculated based on historical data and the hybrid model EMD-SARIMA for air pollution and a solar production forecast is presented. The methodology was tested in the Sarajevo Canton, taking into account 35,000 households. In order to ensure clean air, renewable electric energy use for household heating should be implemented. The widespread use of inefficient individual heating systems characterized by inefficient and expensive use of firewood and the use of coal in individual furnaces in populated areas are the main problems of internal and urban air pollution in Sarajevo Canton. In order to reduce energy poverty in Sarajevo Canton, the use of a floating photovoltaic power plant located on Lake Jablanica with a capacity of 30 MW and the solar prosumers with capacity of 115 MW to provide the 196 GWh necessary for heating electrification of 35,000 households is implemented in this paper. Finally, based on correlation between AQI forecast and solar production it was calculated that the values of the AQI, considering the application of solar energy during 150 days (five months) in one heating season, have significantly decreased. Also renewable energy sources have a very important role in reducing carbon dioxide (CO2) emissions into the atmosphere and reducing urban pollution. With this approach, households would be heated by renewable electricity, which would make Sarajevo a cleaner, smarter city.
Parametric Study of Air Infiltration in Residential Buildings—The Effect of Local Conditions on Energy Demand
Authors: Miszczuk Artur , Heim Dariusz
Published: December 2020

Airtightness is nowadays one of the physical parameters which determine overall building energy performance. In a wide range of states, the upper limit for air change rate at a Pa (na), air permeability rate at a Pa (qa), or specific leakage rate at a Pa (wa) is determined by the formal regulations. It should be highlighted that airtightness requirements are mainly the same around the world, disregarding any site and climatic conditions. The main goal of the presented work was to reveal the effect of individual location and surrounding infiltration rate and heat demand. The analyses were done using numerical techniques and computational models of the three buildings developed and calibrated based on the blower door test results. The compared buildings characterize by a similar geometry but differ in the air change rate at 50 Pa (n50). Analyses done for different locations and levels of sheltering by surrounding elements allow the determination of the real effect of local conditions. The obtained differences in energy demand between two locations from the same climatic zone were from 70% to 90%, depending on the airtightness of the buildings. Considering different sheltered conditions, the differences for the same location can be even 200%. The obtained results allowed for the formulation of the general conclusion that building location and level of exposure could be considered in future airtightness regulations.
Economic Assessment of a PV Hybridized Linear Fresnel Collector Supplying Air Conditioning and Electricity for Buildings
Authors: Montenon Alaric Christian , Papanicolas Costas
Published: December 2020

The present study evaluates the potential upgrade of a Linear Fresnel Reflector (LFR) collector at the Cyprus Institute (CyI) with photovoltaics via the calculation of the Levelized Cost Of Heat (LCOH). For over 4 years the collector has been supplying heating and cooling to the Novel Technologies Laboratory (NTL) of the Cyprus Institute (CyI). Extensive measurements have been carried out both on the LFR and NTL to render real numbers in the computations. This hybridization would be undertaken with the installation of PV arrays under mirrors, so that the collector is able to either reflect direct radiation to the receiver to process heat or to produce electricity directly in the built environment. The main objective is the decrease of the LCOH of Linear Fresnel collectors, which hinders their wider deployment, while air conditioning demand is globally booming. The results show that the LCOH for a small LFR to supply air conditioning is high, c€25.2–30.1 per kWh, while the innovative PV hybridization proposed here decreases it. The value of the study resides in the real data collected in terms of thermal efficiency, operation, and maintenance.
Potential Energy, Demand, Emissions, and Cost Savings Distributions for Buildings in a Utility’s Service Area
Authors: Bass Brett , New Joshua , Copeland William
Published: December 2020

Several companies, universities, and national laboratories are developing urban-scale energy modeling that allows the creation of a digital twin of buildings for the simulation and optimization of real-world, city-sized areas. Prior to simulation-based assessment, a baseline of savings for a set of utility-defined use cases was established to clarify the initial business case for specific energy efficient building technologies. In partnership with a municipal utility, 178,337 OpenStudio and EnergyPlus models of buildings in the utility’s 1400 km2 service area were created, simulated, and assessed with measures for quantifying energy, demand, cost, and emissions reductions of each building. The method of construction and assumptions behind these models is discussed, definitions of example measures are provided, and distribution of savings across the building stock is provided under a maximum technical adoption scenario.
3D Electromagnetic Field Analysis Applied to Evaluate the Accuracy of a Voltage Transformer under Distorted Voltage
Authors: Lesniewska Elzbieta , Kaczmarek Michal , Stano Ernest
Published: December 2020

Voltage transformers (VTs) are an important element of the measuring system that allows measuring the energy flow in medium and high voltage networks. Additional problems with the accuracy of the measurement introduced by the appearance of sources and nonlinear receivers cause deformation of the voltage shape in the energy system. Due to the high metrological requirements, the design of voltage transformers requires high accuracy (for class 0.2 ΔU ≤ 0.2, phase displacement ≤10 min), which is not possible with the use of analytical methods using approximate models. Therefore, only the application of numerical modeling by the finite element method, taking into account real three-dimensional phenomena, allows achieving high modeling accuracy. The article concerns the phenomenon of the influence of voltage higher harmonics of supply voltage on the accuracy (up to the 100th harmonic) of the measuring inductive voltage transformer (IVT). The applied modeling method takes into account the phenomena in the transformer core and the circuit equations resulting from the winding arrangement, which allows for the study of the deformation voltage transformation. Experimental tests on a real model to evaluate the method used were necessary. The article presents simulations for a model transformer, and results have been confirmed by experimental tests.
Lyapunov-Function-Based Controller for Single-Phase NPC Quasi-Z-Source Inverter with 2ω Frequency Ripple Suppression
Authors: Bayhan Sertac , Komurcugil Hasan
Published: December 2020

This paper proposes a high-performance control technique based on Lyapunov’s stability theory for a single-phase grid-connected neutral-point-clamped quasi-impedance source inverter with LCL filter. The Lyapunov function based control is employed to regulate the inverter output current, whereas the proportional resonant controller is used to produce the reference of the inverter output current that is needed in the Lyapunov function based control. Use of proportional resonant controller ensures the zero steady-state error in the grid current. An important feature of the proposed Lyapunov function based control is the achievement of resonance damping without using a dedicated damping method. Furthermore, the modified simple boost control technique is proposed to eliminate the double-line frequency ripples in the quasi-impedance source inductor currents and minimize the double-line frequency ripples in the quasi-impedance source capacitor voltages. The proposed control technique considerably reduces the inverter size, weight, and cost as well as increases overall system efficiency since the required inductances and capacitances sizes are lower. Experimental results obtained from a 2.5 kW neutral-point-clamped quasi-impedance source inverter prototype are presented to validate the performance of the Lyapunov function based control technique.
Solar Energy Potential in the Yangtze River Delta Region—A GIS-Based Assessment
Authors: Odhiambo Morice R. O. , Abbas Adnan , Wang Xiaochan , Mutinda Gladys
Published: December 2020

Decarbonization of electrical power generation is an essential necessity in the reduction of carbon emissions, mitigating climate change and attaining sustainable development. Solar energy as a substitution for fossil fuel-based energy sources has the potential to aid in realizing this sustainable future. This research performs a geographic information systems (GIS)-based assessment of the solar energy potential in the Yangtze River Delta region (YRDR) of China using high-resolution solar radiation data combined with geographical, social, environmental and cultural constraints data. The solar energy potential is evaluated from the geographical and technical perspective, and the results reveal that the YRDR is endowed with rich solar energy resources, with the geographical potential in the suitable areas ranging from 1446 kWh/m2 to 1658 kWh/m2. It is also estimated that the maximum solar capacity potential could be up to 4140.5 GW, illustrating the high potential available for future capacity development in this region. Realizing this significant potential as an alternative for fossil fuel-based electricity generation would result in a substantial mitigation of CO2 emissions in this region, where air pollution is severe. Potential evaluations found that Jiangsu and Anhui provinces provide the most optimal areas for the development of solar photovoltaics (PV) installations, as they have the highest geographical and technological solar energy potential. Further, findings of the case study undertaken at a solar PV plant show disparities between actual generated power and technical solar potential, highlighting the significance of utilizing solar radiation data from local ground-based meteorological stations. This study provides policy makers and potential investors with information on solar energy potential in the Yangtze River Delta region that would contribute to solar power generation development.
Three-Dimensional Simulation of New Car Profile
Authors: Mansour Hamdy , Afify Rola , Kassem Omar
Published: December 2020

Aerodynamics has identified remarkable development in the improvement of fuel efficiency, reducing wind noise and increasing engine cooling. Moving body profile controls fuel the consumption rate. This paper discusses a novel car profile consisting of two airfoils Roncz (car profile) and National Advisory Committee for Aeronautics NACA 10 (car sides). They are used to create a streamlined body. Three-Dimensional numerical simulations of the full scale model (half domain) are performed to examine the effect of car profile on the drag coefficient and thus fuel consumption. Simulations are considered over a range of air flow velocities, from 20 to 45 km/h in a step of 5 km/h. The ahmed body is used to validate the results. Results are shown graphically for coefficients of drag and lift and pressure and velocity contours. They show that the design of the car profile is effective.
Modeling Post-Liberalized European Gas Market Concentration—A Game Theory Perspective
Authors: Hamie Hassan , Hoayek Anis , Auer Hans
Published: December 2020

The question of whether the liberalization of the gas industry has led to less concentrated markets has attracted much interest among the scientific community. Classical mathematical regression tools, statistical tests, and optimization equilibrium problems, more precisely non-linear complementarity problems, were used to model European gas markets and their effect on prices. In this research, the parametric and nonparametric game theory methods are employed to study the effect of the market concentration on gas prices. The parametric method takes into account the classical Cournot equilibrium test, with assumptions on cost and demand functions. However, the non-parametric method does not make any prior assumptions, a factor that allows greater freedom in modeling. The results of the parametric method demonstrate that the gas suppliers’ behavior in Austria and The Netherlands gas markets follows the Nash–Cournot equilibrium, where companies act rationally to maximize their payoffs. The non-parametric approach validates the fact that suppliers in both markets follow the same behavior even though one market is more liquid than the other. Interestingly, our findings also suggest that some of the gas suppliers maximize their ‘utility function’ not by only relying on profit, but also on some type of non-profit objective, and possibly collusive behavior.
Re-Turning to the Event of Colonisation in New South Wales
Authors: Davies Bronwyn
Published: December 2020

In this paper, I re-turn to the event of colonisation in New South Wales. I draw on the journal of my ancestor, David Collins, who came to New South Wales on the First Fleet in 1788 to take up the position of the colony’s Judge Advocate and Secretary to Governor Phillip. Drawing on Collins’ account of the first years of the colony, I contemplate the difficult interface between the Indigenous civilisation that existed in New South Wales prior to the event of colonisation, and the British newcomers’ civilisation as it was thought and practiced in those first years of the colony. That im/possible interface still reverberates in the present, implicating me as a 6th-generation newcomer.
Fruit Ripening Development of ‘Valencia’ Orange Trees Grafted on Different ‘Trifoliata’ Hybrid Rootstocks
Authors: Domingues Allan Ricardo , Marcolini Ciro Daniel Marques , Gonçalves Carlos Henrique da Silva , Gonçalves Leandro Simões Azeredo , Roberto Sergio Ruffo , Carlos Eduardo Fermino
Published: December 2020

The development of fruit ripening of ‘Valencia’ orange trees [Citrus sinensis (L.) Osb.] grafted on the following ‘Trifoliata’ hybrid rootstocks: ‘US-852’, IPEACS-256 and IPEACS-264 citrandarins, and F.80-3, ‘W-2’ citrumelo, and ‘Swingle’ citrumelo (control), was assessed in three different subtropical locations: Rancho Alegre (RA); São Sebastião da Amoreira (SSA); and São Jerônimo da Serra (SJS), Parana state, Brazil. The climate of the RA and SSA locations was classified as Cfa with hot summers, whereas that of the SJS location was Cfb with temperate summers, which are located at 380, 650, and 835 m a.s.l., respectively. A completely randomized block design with four replications and four trees per plot was used as a statistical model for each location. The soluble solids (SS) content, titratable acidity (TA), and the maturation index (MI) or ratio (SS/TA) of the juice, as well as the citrus color index (CCI) of fruit skin, were assessed monthly, beginning 200 days after flowering until harvest, totaling seven sampling dates. The data sets of each location were analyzed independently through a two-way analysis of variance (ANOVA) involving rootstocks in a split plot array in time (days) to allow for the assessment of the significance of the main effects, complemented by regression analysis. In general, the ripening of ‘Valencia’ orange fruits was influenced by the different ‘Trifoliata’ hybrid rootstocks. At the RA location, trees on IPEACS-256 and’ US-852’ citrandarins had the highest SS, and on ‘US-852’ citrandarin had the highest MI, reaching the MIim earlier than the other rootstocks. The highest CCI was achieved when trees were on IPEACS-256 citrandarin. At the SSA location, trees on ‘US-852’, IPEACS-256, and IPEACS-264 citrandarins had the highest SS, but on ‘US–852’ had the highest MI, reaching the earliest MIim among the rootstocks. The highest CCI was achieved when trees were on ‘US-852’ and IPEACS-256 citrandarins. In the SSJ location, there was no significant effect of the rootstocks on and of the variables of ‘Valencia’ orange fruit. This assessment can be useful in the planning of new orchards producing high-quality fruit with desirable features for the orange juice industry.
Time Use Implication of Clean Cookstoves in Rural Settings in Ghana: A Time Use Study
Authors: Prah Rebecca Kyerewaa Dwommoh , Carrion Daniel , Oppong Felix Boakye , Tawiah Theresa , Mujtaba Mohammed Nuhu , Gyaase Stephaney , Kwarteng Adolphine , Ae-Ngibise Kenneth Ayuurebobi , Agyei Oscar , Twumasi Mieks , Agbokey Francis , Asante Kwaku Poku , Jack Darby W.
Published: December 2020

Whilst the health benefit of using clean cookstoves and fuels is widely known, there is limited information on the non-health benefit of these stoves, especially in low-middle-income countries. This paper reports the time use implications of using clean cookstoves and fuels by comparing liquified petroleum gas (LPG), an improved biomass cookstove (BioLite), and traditional biomass cookstoves (three-stone fires) in Ghana. Using survey-based time diaries, information on all the activities undertaken by study participants during a 24-h was collected and analyzed. The findings of the study show that LPG users spent significantly less time gathering firewood compared to the users of improved cookstoves and three-stone fires. LPG users spent slightly less time per cooking episode, generally, and there was no significant difference in cooking time across the three cookstoves mostly due to stove stacking. Time spent engaging in economic activities was highest for LPG users and improved biomass cookstove users, at least when compared to three-stone fire users. In this study, we provide evidence on the time use implications of clean cookstoves, highlighting their non-health benefits and supporting efforts towards the adoption and sustained used of clean cookstoves