bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Transformation Plasticity on Gear Distortion and Residual Stresses in Carburizing Quenching Simulation
Authors: Li Xusheng , Ju Dongying , Cao Jianting , Wang Sirui , Chen Yong , He Fangbo , Li Hui
Published: October 2021

This paper addresses the effect of gear steel on distortion and residual stresses due to phase transformation in carburizing and quenching. In particular, the martensitic and bainitic phase transformation expansion and transformation plasticity properties of two automotive gearbox steels (20CrMnTiH and 20MnCr5) and their physical parameters are measured by experiments of transformation plasticity properties. Numerical simulations of the actual carburizing and quenching process of the gearbox spline helical gears were carried out in combination with the thermal and mechanical properties with temperature variations calculated by the material design software JMAT-Pro. In particular, the phase transformation properties of the two materials and their influence on the distortion and residual stresses after carburizing and quenching were verified by experiments of transformation plasticity and numerical simulations. A reliable basis is provided for predicting the distortion mechanism of gear steels in carburizing and quenching.
The Difference of Marginal Bone Preservation between Dental Implants with Non-Threaded or Micro-Threaded Collar Designs
Authors: Almasri Mazen
Published: October 2021

This study analyzes the marginal bone loss (MBL) among dental implants characterized with non-threaded collar design (NT) when compared to the more classic micro-threaded collar design (MC) as such might reflect the future dentogengival esthetics, implant metal show, and mucositis. A total of 112 patients who received 311 implants have been included in the study and analyzed for their postoperative MBL using sequential periapical radiographs. The prevalence of postoperative peri-implant mucositis was recorded as well. The periapical radiographic comparison was performed between the immediate postoperative record and at the 24-month recall visit. Among the 311 implants, 124 (39.9%) had NT implants, and 187 (60.1%) had MC implants. Out of the 112 patients, 37 (44.6%) were females, and 10 (34.5%) were males included in the NT group. In contrast, 46 (55.4%) females and 19 (65.5%) males were in the MC group. The mean age among the two groups was 41.43 ± 15.900 and 46.68 ± 16.070, respectively. In contrast, the mean MBL among the groups were 0.544 ± 0.7129 and 0.061 ± 0.2648, respectively. The change in MBL was not positively correlated with gender (p-value = 0.154) or age (p-value = 0.115) in both groups. However, there was a significant difference (p-value = 0.001, X2 = 62.796, Df = 4) of MBL between the two implant systems themselves. The MBL was higher in people implanted with the NT system when compared to MC. Therefore, the MC implant system can be a better choice for marginal bone preservation, especially in restoring esthetically demanding areas in the mouth.
Cocrystals versus Salts of Fluorescein
Authors: Răducă Mihai , Mădălan Augustin M.
Published: October 2021

A series of nitrogen-containing organic molecules (4,4’-bipyridyl; trans-1,2-bis(4-pyridyl)ethylene; 1,2-bis(4-pyridyl)ethane; 4-aminopyridine and trans-1,4-diaminocyclohexane) was envisaged for cocrystallization experiments together with fluorescein. These compounds, containing pyridyl or/and amino nitrogen atoms, can act either as hydrogen bond acceptors for the phenol groups of fluorescein-generating cocrystals or as proton acceptors forming organic salts. Five cocrystals were obtained with the partners containing only pyridyl groups: {(H2Fl)2(bipy)} (1); {(H2Fl)2(bipy)(MeOH)2} (2); {(H2Fl)2(bpete)(EtOH)2} (3); {(H2Fl)(bpete)} (4); {(H2Fl)(bpeta)} (5). The compounds bearing amino groups deprotonate fluorescein producing salts: [(HFl)(Hampy)]∙2H2O (6); [(HFl)(Hampy)] (7); [(Fl)(H2diach)]∙3H2O (8); [(HFl)2(H2diach)]∙2H2O∙EtOH (9); and [(HFl)2(Fl)2(H2diach)3]∙4H2O (10). Optical properties of the cocrystals and salts were investigated.
Development and Optimization of VGF-GaAs Crystal Growth Process Using Data Mining and Machine Learning Techniques
Authors: Dropka Natasha , Böttcher Klaus , Holena Martin
Published: October 2021

The aim of this study was to assess the ability of the various data mining and supervised machine learning techniques: correlation analysis, k-means clustering, principal component analysis and decision trees (regression and classification), to derive, optimize and understand the factors influencing VGF-GaAs growth. Training data were generated by Computational Fluid Dynamics (CFD) simulations and consisted of 130 datasets with 6 inputs (growth rate and power of 5 heaters) and 5 outputs (interface position and deflection, and temperatures at various positions in GaAs). Data mining results confirmed a good dispersion of the training data without the feasibility of a dimensionality reduction. Data clustering was observed in relation to the position of the crystallization front relative to the side heaters. Based on the statistical performance criteria and training results, decision trees identified the most decisive inputs and their ranges for a favorable interface shape and to keep GaAs temperature beyond limits for heavy arsenic evaporation. Decision trees are a recommendable machine learning technique with short training times and acceptable predictive accuracy based on small volume of CFD training data, capable of providing guidelines for understanding the crystal growth process, which is a prerequisite for the growth of low-cost, high-quality bulk crystals.
Incorporation of Iron(II) and (III) in Hydroxyapatite—A Theoretical Study
Authors: Makshakova Olga Nikolaevna , Shurtakova Daria Vladimirovna , Vakhin Alexey Vladimirovich , Grishin Peter Olegovich , Gafurov Marat Revgerovich
Published: October 2021

Hydroxyapatite (Ca10(PO4)6(OH)2, HAp) doped with various transition metals has generated great interest in view of its potential application in a wide variety of fields, including in catalysis as a support with a series of attractive properties. Despite a large number of experimental works devoted to the synthesis and application of iron-substituted hydroxyapatites, problems concerning the location, introduced defects, and charge compensation schemes for Fe2+ and/or Fe3+ cations in the crystal structure of HAp remain unclear. This paper is devoted to the comprehensive analysis of iron (II) and (III) introduction into the HAp lattice by density functional theory (DFT) calculations. We show that the inclusion of Fe2+ in the Ca(1) and Ca(2) positions of HAp is energetically comparable. For the Fe3+, there is a clear preference to be included in the Ca(2) position. The inclusion of iron results in cell contraction, which is more pronounced in the case of Fe3+. In addition, Fe3+ may form a shorter linkage to oxygen atoms. The incorporation of both Fe2+ and Fe3+ leads to notable local reorganization in the HAp cell.
Polymeric Terbium(III) Squarate Hydrate as a Luminescent Magnet
Authors: Takano Rina , Ishida Takayuki
Published: October 2021

Polymeric terbium(III) squarate hydrate [{Tb2(C4O4)3(H2O)8}n] was prepared from TbCl3 or Tb2O3 and squaric acid. The crystal structure was determined in a monoclinic Pc space group, and the whole molecular arrangement gives a sandwiched two-dimensional structure. The coordination polyhedra are described as a square antiprism. The solid complex emits green light under UV irradiation at room temperature with the quantum yield of 25%. Although Tb3+ is a non-Kramers ion, the alternating-current magnetic susceptibility showed frequency dependence in a 2000-Oe DC field, and the effective energy barrier for magnetization reorientation was 33(2) K. Thus, [{Tb2(C4O4)3(H2O)8}n] displayed functions of a potential luminescent magnet.
16S rRNA Gene Amplicon Sequencing Data of the Iron Quadrangle Ferruginous Caves (Brazil) Shows the Importance of Conserving This Singular and Threatened Geosystem
Authors: Lemes Camila G. C. , Villa Morghana M. , Felestrino Érica B. , Perucci Luiza O. , Assis Renata A. B. , Cordeiro Isabella F. , Fonseca Natasha P. , Guerra Lara C. C. , Caneschi Washington L. , Moraes Lauro Â. G. , do Carmo Flávio F. , Kamino Luciana H. Y. , Vale Pedro N. C. , Guima Suzana E. S. , Setubal João C. , Salgado André A. R. , Moreira Leandro M.
Published: October 2021

The Iron Quadrangle (IQ) is one of the main iron ore producing regions of the world. The exploitation of its reserves jeopardizes the high biological endemism associated with this region. This work aimed to understand the diversity and bacterial potential associated with IQ caves. Floor and ceiling samples of seven ferruginous caves and one quartzite cave were collected, and their microbial relative abundance and diversity were established by 16S rRNA gene amplicon sequencing data. The results showed that ferruginous caves present higher microbial abundance and greater microbial diversity compared to the quartzite cave. Many species belonging to genera found in these caves, such as Pseudonocardia and Streptacidiphilus, are known to produce biomolecules of biotechnological interest as macrolides and polyketides. Moreover, comparative analysis of microbial diversity and metabolic potential in a biofilm in pendant microfeature revealed that the microbiota associated with this structure is more similar to the floor rather than ceiling samples, with the presence of genera that may participate in the genesis of these cavities, for instance, Ferrovum, Geobacter, and Sideroxydans. These results provide the first glimpse of the microbial life in these environments and emphasize the need of conservation programs for these areas, which are under intense anthropogenic exploration.
Polar Vortex Multi-Day Intensity Prediction Relying on New Deep Learning Model: A Combined Convolution Neural Network with Long Short-Term Memory Based on Gaussian Smoothing Method
Authors: Peng Kecheng , Cao Xiaoqun , Liu Bainian , Guo Yanan , Xiao Chaohao , Tian Wenlong
Published: October 2021

The variation of polar vortex intensity is a significant factor affecting the atmospheric conditions and weather in the Northern Hemisphere (NH) and even the world. However, previous studies on the prediction of polar vortex intensity are insufficient. This paper establishes a deep learning (DL) model for multi-day and long-time intensity prediction of the polar vortex. Focusing on the winter period with the strongest polar vortex intensity, geopotential height (GPH) data of NCEP from 1948 to 2020 at 50 hPa are used to construct the dataset of polar vortex anomaly distribution images and polar vortex intensity time series. Then, we propose a new convolution neural network with long short-term memory based on Gaussian smoothing (GSCNN-LSTM) model which can not only accurately predict the variation characteristics of polar vortex intensity from day to day, but also can produce a skillful forecast for lead times of up to 20 days. Moreover, the innovative GSCNN-LSTM model has better stability and skillful correlation prediction than the traditional and some advanced spatiotemporal sequence prediction models. The accuracy of the model suggests important implications that DL methods have good applicability in forecasting the nonlinear system and vortex spatial–temporal characteristics variation in the atmosphere.
A Novel q-Rung Dual Hesitant Fuzzy Multi-Attribute Decision-Making Method Based on Entropy Weights
Authors: Kou Yaqing , Feng Xue , Wang Jun
Published: October 2021

In this paper, a new multiple attribute decision-making (MADM) method under q-rung dual hesitant fuzzy environment from the perspective of aggregation operators is proposed. First, some aggregation operators are proposed for fusing q-rung dual hesitant fuzzy sets (q-RDHFSs). Afterwards, we present properties and some desirable special cases of the new operators. Second, a new entropy measure for q-RDHFSs is developed, which defines a method to calculate the weight information of aggregated q-rung dual hesitant fuzzy elements. Third, a novel MADM method is introduced to deal with decision-making problems under q-RDHFSs environment, wherein weight information is completely unknown. Finally, we present numerical example to show the effectiveness and performance of the new method. Additionally, comparative analysis is conducted to prove the superiorities of our new MADM method. This study mainly contributes to a novel method, which can help decision makes select optimal alternatives when dealing with practical MADM problems.
Analysis of Performance of Cavitation Models with Analytically Calculated Coefficients
Authors: Savio Andrea , Cianferra Marta , Armenio Vincenzo
Published: October 2021

Cavitation is often simulated using a mixture model, which considers the transport of an active scalar, namely the vapor fraction αv. Source and sink terms of the transport equation of αv, namely vaporization and condensation terms, rule the dynamics of the cavity and are described through different models. These models contain empirical coefficients generally calibrated through optimization processes. The purpose of this paper is to propose an analytical approach for the calculation of the coefficients, based on the time scales of vaporization and condensation processes. Four different models are compared considering as a test-case a two-dimensional flow around a cylinder. Some relevant quantities are analyzed both for standard value of coefficients, as found in the literature, and the coefficients calculated through the analytical approach. The study shows that the analytical computation of the coefficients of the model substantially improve the results, and the models considered give similar results, both in terms of cavitation regime and mean vapor fraction produced.
Comment on Hamayun et al. Evaluation of Two-Column Air Separation Processes Based on Exergy Analysis. Energies 2020, 13, 6361
Authors: Variny Miroslav , Jediná Dominika , Furda Patrik
Published: October 2021

Oxygen production from air belongs to energy-intense processes and, as a result, possibilities for its decrease are a frequent topic of optimization studies, often performed with simulation software such as Aspen Plus or Aspen HYSYS. To obtain veritable results and sound solutions, a suitable calculation method hand in hand with justified assumptions and simplifications should form the base of any such studies. Thus, an analysis of the study by Hamayun et al., Energies 2020, 13, 6361, has been performed, and several weak spots of the study, including oversimplified assumptions, improper selection of a thermodynamic package for simulation and omission of certain technological aspects relevant for energy consumption optimization studies, were identified. For each of the weak spots, a recommendation based on good praxis and relevant scientific literature is provided, and general recommendations are formulated with the hope that this comment will aid all researchers utilizing Aspen Plus and Aspen HYSYS software in their work.
A Decarbonization Roadmap for Singapore and Its Energy Policy Implications
Authors: Lau Hon Chung , Ramakrishna Seeram , Zhang Kai , Hameed Mohamed Ziaudeen Shahul
Published: October 2021

As a signatory to the Paris Agreement, Singapore is committed to achieving net-zero carbon emissions in the second half of the century. In this paper, we propose a decarbonization roadmap for Singapore based on an analysis of Singapore’s energy landscape and a technology mapping exercise. This roadmap consists of four major components. The first component, which also underpins the other three components, is using centralized post-combustion carbon capture technology to capture and compress CO2 emitted from multiple industrial sources in Jurong Island. The captured CO2 is then transported by ship or an existing natural gas pipeline to a neighboring country, where it will be stored permanently in a subsurface reservoir. Important to the success of this first-of-a-kind cross-border carbon capture and storage (CCS) project is the establishment of a regional CCS corridor, which makes use of economies of scale to reduce the cost of CO2 capture, transport, and injection. The second component of the roadmap is the production of hydrogen in a methane steam reforming plant which is integrated with the carbon capture plant. The third component is the modernizing of the refining sector by introducing biorefineries, increasing output to petrochemical plants, and employing post-combustion carbon capture. The fourth component is refueling the transport sector by introducing electric and hydrogen fuel cell vehicles, using biofuels for aviation and hydrogen for marine vessels. The implications of this roadmap on Singapore’s energy policies are also discussed.
Heat Transfer Augmentation through Different Jet Impingement Techniques: A State-of-the-Art Review
Authors: Hussain Liaqat , Khan Muhammad Mahabat , Masud Manzar , Ahmed Fawad , Rehman Zabdur , Amanowicz Łukasz , Rajski Krzysztof
Published: October 2021

Jet impingement is considered to be an effective technique to enhance the heat transfer rate, and it finds many applications in the scientific and industrial horizons. The objective of this paper is to summarize heat transfer enhancement through different jet impingement methods and provide a platform for identifying the scope for future work. This study reviews various experimental and numerical studies of jet impingement methods for thermal-hydraulic improvement of heat transfer surfaces. The jet impingement methods considered in the present work include shapes of the target surface, the jet/nozzle–target surface distance, extended jet holes, nanofluids, and the use of phase change materials (PCMs). The present work also includes both single-jet and multiple-jet impingement studies for different industrial applications.
Energy Savings after Comprehensive Renovations of the Building: A Case Study in the United Kingdom and Italy
Authors: Araya Mejías Olman , Montalvo Cristina , García-Berrocal Agustín , Cubillo María , Gordaliza Daniel
Published: October 2021

The housing sector is one of the largest energy consumers in the world. There is an urgent need to renovate the housing stock of existing buildings. Therefore, it is necessary to correctly calculate the energy savings that can be obtained in a renovation project. The correct collection of energy data, the main variables that affect consumption, and people’s usage habits are fundamental elements to quantify the success or consequences that occur in an energy efficiency project. This research study quantifies the results of the energy savings of the European project DREEAM (District Scale Renovation for Energy Efficiency and Market Uptake). This article aims to facilitate the calculation of energy savings with mathematical linear regression models in two different climatic zones in Europe. Furthermore, it aims to improve the calculation of energy savings with mathematical models based on energy data and variables that affect consumption before and after renovations. The variables used for the calculation are hours of use, degree days, and reading days. Tenant behavior has been found to play an important role in actual measured savings. Additionally, the energy consumption patterns of the tenants are different after the renovations.
Determination of the Extent of the Rock Destruction Zones around a Gasification Channel on the Basis of Strength Tests of Sandstone and Claystone Samples Heated at High Temperatures up to 1200 °C and Exposed to Water
Authors: Skrzypkowski Krzysztof , Zagórski Krzysztof , Zagórska Anna
Published: October 2021

This article presents the results of laboratory tests regarding the influence of high temperatures on changes in the strength and structural parameters of rocks that are present in the immediate vicinity of a gasification channel. Sandstone and claystone samples were heated at 300 °C, 600 °C, 900 °C and 1200 °C. Additionally, the heated samples were placed in water for 24 h. The results of the laboratory tests were used in the numerical simulation using RS2 software. The main goal of modeling was to determine the extent of the rock destruction zone around the gasification channel for dry and wet rock masses. In the numerical simulations, three widths of the gasification channel and three ranges of high-temperature impact were modeled. On the basis of the obtained results, it was found that the extent of rock destruction, both in the roof and in the floor, is greater by several percent for a wet rock mass. For the first time, this research presents the effect of water on heated rock samples in terms of the underground coal gasification process. The results of laboratory tests and numerical simulations clearly indicate a reduction in strength, deformation and structural parameters for the temperature of 1200 °C.
The Contribution of Bottom-Up Energy Models to Support Policy Design of Electricity End-Use Efficiency for Residential Buildings and the Residential Sector: A Systematic Review
Authors: Sanchez-Escobar Marlene Ofelia , Noguez Julieta , Molina-Espinosa Jose Martin , Lozano-Espinosa Rafael , Vargas-Solar Genoveva
Published: October 2021

Bottom-up energy models are considered essential tools to support policy design of electricity end-use efficiency. However, in the literature, no study analyzes their contribution to support policy design of electricity end-use efficiency, the modeling techniques used to build them, and the policy instruments supported by them. This systematic review fills that gap by identifying the current capability of bottom-up energy models to support specific policy instruments. In the research, we review 192 publications from January 2015 to June 2020 to finally select 20 for further examination. The articles are analyzed quantitatively in terms of techniques, model characteristics, and applied policies. The findings of the study reveal that: (1) bottom-up energy models contribute to the support of policy design of electricity end-use efficiency with the application of specific best practices (2) bottom-up energy models do not provide a portfolio of analytical methods which constraint their capability to support policy design (3) bottom-up energy models for residential buildings have limited policy support and (4) bottom-up energy models’ design reveals a lack of inclusion of key energy efficiency metrics to support decision-making. This study’s findings can help researchers and energy modelers address these limitations and create new models following best practices.
Odour Nuisance at Municipal Waste Biogas Plants and the Effect of Feedstock Modification on the Circular Economy—A Review
Authors: Wiśniewska Marta , Kulig Andrzej , Lelicińska-Serafin Krystyna
Published: October 2021

The increase in the amount of municipal solid waste (MSW) generated, among other places, in households is a result of the growing population, economic development, as well as the urbanisation of areas with accompanying insufficiently effective measures to minimise waste generation. There are many methods for treating municipal waste, with the common goal of minimising environmental degradation and maximising resource recovery. Biodegradable waste, including selectively collected biowaste (BW), also plays an essential role in the concept of the circular economy (CE), which maximises the proportion of waste that can be returned to the system through organic recycling and energy recovery. Methane fermentation is a waste treatment process that is an excellent fit for the CE, both technically, economically, and environmentally. This study aims to analyse and evaluate the problem of odour nuisance in municipal waste biogas plants (MWBPs) and the impact of the feedstock (organic fraction of MSW-OFMSW and BW) on this nuisance in the context of CE assumptions. A literature review on the subject was carried out, including the results of our own studies, showing the odour nuisance and emissions from MWBPs processing both mixed MSW and selectively collected BW. The odour nuisance of MWBPs varies greatly. Odour problems should be considered regarding particular stages of the technological line. They are especially seen at the stages of waste storage, fermentation preparation, and digestate dewatering. At examined Polish MWBPs cod ranged from 4 to 78 ou/m3 for fermentation preparation and from 8 to 448 ou/m3 for digestate dewatering. The conclusions drawn from the literature review indicate both the difficulties and benefits that can be expected with the change in the operation of MWBPs because of the implementation of CE principles.
In Situ Deformation Analysis of a Fracture in Coal under Cyclic Loading and Unloading
Authors: Liu Zhihui , Yang Yongfei , Li Yingwen , Li Jiaxue
Published: October 2021

The deformation analysis of fractures is vital for advantageous development of oil and gas fields, especially the coalbed methane (CBM) reservoir, since the change of fracture parameters can be directly evaluated through fracture deformation analysis. Then the flow capacity of CBM and the effect of various stimulation methods can be analyzed. In this study, X-ray CT image analysis is used to quantitatively characterize the deformation of a coal fracture in situ, and the evolution of fracture aperture under cyclic loading is presented. Furthermore, dimensionless permeability at different confining pressures by the Lattice Boltzmann method is simulated. The current results indicate that the fracture deformation changes significantly under cyclic loading. A dramatic change is observed in the initial loading stage, in which the coal is strongly compacted, and the fracture aperture and permeability are reduced to 13.9% and 0.1%, respectively, when the confining pressure is loaded to 10 MPa. When unloading to 0 MPa, the fracture aperture and dimensionless permeability are far less than that of the initial 0 MPa. It is worth noting that the deformation of the second cycle fracture is weaker, and the change range of permeability and aperture of coal fracture becomes smaller, but when unloading to 0 MPa in the second cycle, the fracture permeability can be restored to 50.8% compared with 0 MPa of the loading stage. Additionally, a special phenomenon has been observed that under cyclic loading, even when the confining pressure reaches 10 MPa, some areas of the fracture are still not closed. We infer that there are some large pore structures in fracture space, and high confining pressure leads to fracture closure, but the deformation of the pore structure is not prominent compared with the fracture space. These characteristics of fracture deformation are of great significance for the production of CBM and are worthy of further study.
Novel Fuzzy Control Energy Management Strategy for Fuel Cell Hybrid Electric Vehicles Considering State of Health
Authors: Hu Xiao , Liu Shikun , Song Ke , Gao Yuan , Zhang Tong
Published: October 2021

Due to the low efficiency and high pollution of conventional internal combustion engine vehicles, the fuel cell hybrid electric vehicles are expected to play a key role in the future of clean energy transportation attributed to the long driving range, short hydrogen refueling time and environmental advantages. The development of energy management strategies has an important impact on the economy and durability, but most strategies ignore the aging of fuel cells and the corresponding impact on hydrogen consumption. In this paper, a rule-based fuzzy control strategy is proposed based on the constructed data-driven online estimation model of fuel cell health. Then, a genetic algorithm is used to optimize this fuzzy controller, where the objective function is designed to consider both the economy and durability by combining the hydrogen consumption cost and the degradation cost characterized by the fuel cell health status. Considering that the rule-based strategy is more sensitive to operating conditions, this paper uses an artificial neural network for predictive control. The results are compared with those obtained from the genetic algorithm optimized fuzzy controller and are found to be very similar, where the prediction accuracy is assessed using MAPE, RMSE and 10-fold cross-validation. Experiments show that the developed strategy has a good generalization capability for variable driving cycles.
Unveiling the Nexus between Access to Electricity, Firm Size and SME’s Performance in Bangladesh: New Evidence Using PSM
Authors: Chowdhury Mohammad Abir Shahid , Chuanmin Shuai , Sokolová Marcela , Rahman ABM Munibur , Akbar Ahsan , Ali Zahid , Usman Muhammad
Published: October 2021

Uninterrupted availability of energy and power resources is essential for the productivity and smooth functioning of an enterprise. However, constrained by financial resources, smaller firms in developing economies face a plethora of challenges concerning the access to electricity. However, less attention has been paid in the extant literature to explore this phenomenon. The present study investigates the impact of access to electricity on labor productivity in Bangladesh in the presence of electricity constraints, electricity obstacles, and SME firm size. It employs the OLS regression and propensity score matching (PSM) technique for treatment effect to deal with the selection bias and endogeneity issue using the World Bank Enterprise Survey’s cross-sectional firm-level data for 3196 sample firms over the period of 2007–2013. The results provide evidence in support of SMEs’ labor productivity in response to electricity access. Lack of electricity access was partially found to affect SMEs’ labor productivity significantly negatively. Further, the results show a positive impact of firm size on firm performance. However, results from this model appear that constrained SMEs’ access to electricity has a negative relationship with firm performance. The article then suggests several policy implications on changing government regulations regarding the efficient use of renewable energy resources to enhance electricity generation for optimized SME performance and sustainable economic development in Bangladesh.
GHGs Emission from the Agricultural Sector within EU-28: A Multivariate Analysis Approach
Authors: Harsányi Endre , Bashir Bashar , Almhamad Gafar , Hijazi Omar , Maze Mona , Elbeltagi Ahmed , Alsalman Abdullah , Enaruvbe Glory O. , Mohammed Safwan , Szabó Szilárd
Published: October 2021

Climate mitigation and adaptation planning (CMAP) has recently been implemented across the EU-28 to reduce GHG emissions (CO2, CH4, N2O). Thus, the aim of this study was to provide an overview of GHG emissions from the agricultural sector in the EU-28 from 1990 to 2019, and cluster the EU-28 countries regarding their total GHG emissions. The results emphasize the positive impact of CMAP through a negative trend of the total GHG emissions (−2653.01 thousand tons/year, p < 0.05). Despite the positive and not significant trend of the total CO2 emissions, both CH4 and N2O exhibited a negative and significant trend. At the country scale, Italy, the United Kingdom, and the Netherlands showed the highest reduction in total GHG emissions, by −282.61thousand tons/year (p < 0.05), −266.40 thousand tons/year (p < 0.05), and −262.91 thousand tons/year (p < 0.05), respectively. The output of the multivariate analysis approach indicates changes in the pattern of GHG emissions between 1990 and 2019, where CO2 emissions decreased in the case of Poland and Czechia. The output of this study highlights the positive impact of CMAP, adopted by EU countries, in minimizing GHG emissions. Despite some fluctuations in CO2 emissions, strategies for attaining carbon neutrality in the agricultural sector, across the European Union, should be pursued.
Influence of Non-Linearity in Losses Estimation of Magnetic Components for DC-DC Converters
Authors: Corti Fabio , Reatti Alberto , Lozito Gabriele Maria , Cardelli Ermanno , Laudani Antonino
Published: October 2021

In this paper, the problem of estimating the core losses for inductive components is addressed. A novel methodology is applied to estimate the core losses of an inductor in a DC-DC converter in the time-domain. The methodology addresses both the non-linearity and dynamic behavior of the core magnetic material and the non-uniformity of the field distribution for the device geometry. The methodology is natively implemented using the LTSpice simulation environment and can be used to include an accurate behavioral model of the magnetic devices in a more complex lumped circuit. The methodology is compared against classic estimation techniques such as Steinmetz Equation and the improved Generalized Steinmetz Equation. The validation is performed on a practical DC-DC Buck converter, which was utilized to experimentally verify the results derived by a model suitable to estimate the inductor losses. Both simulation and experimental test confirm the accuracy of the proposed methodology. Thus, the proposed technique can be flexibly used both for direct core loss estimation and the realization of a subsystem able to simulate the realistic behavior of an inductor within a more complex lumped circuit.
Wind Speed and Solar Irradiance Prediction Using a Bidirectional Long Short-Term Memory Model Based on Neural Networks
Authors: Alharbi Fahad Radhi , Csala Denes
Published: October 2021

The rapid growth of wind and solar energy penetration has created critical issues, such as fluctuation, uncertainty, and intermittence, that influence the power system stability, grid operation, and the balance of the power supply. Improving the reliability and accuracy of wind and solar energy predictions can enhance the power system stability. This study aims to contribute to the issues of wind and solar energy fluctuation and intermittence by proposing a high-quality prediction model based on neural networks (NNs). The most efficient technology for analyzing the future performance of wind speed and solar irradiance is recurrent neural networks (RNNs). Bidirectional RNNs (BRNNs) have the advantages of manipulating the information in two opposing directions and providing feedback to the same outputs via two different hidden layers. A BRNN’s output layer concurrently receives information from both the backward layers and the forward layers. The bidirectional long short-term memory (BI-LSTM) prediction model was designed to predict wind speed, solar irradiance, and ambient temperature for the next 169 h. The solar irradiance data include global horizontal irradiance (GHI), direct normal irradiance (DNI), and diffuse horizontal irradiance (DHI). The historical data collected from Dumat al-Jandal City covers the period from 1 January 1985 to 26 June 2021, as hourly intervals. The findings demonstrate that the BI-LSTM model has promising performance in terms of evaluation, with considerable accuracy for all five types of historical data, particularly for wind speed and ambient temperature values. The model can handle different sizes of sequential data and generates low error metrics.
Development and Performance Study of Temperature and Humidity Regulator in Baby Incubator Using Fuzzy-PID Hybrid Controller
Authors: Alimuddin Alimuddin , Arafiyah Ria , Saraswati Irma , Alfanz Rocky , Hasudungan Partogi , Taufik Taufik
Published: October 2021

Technological developments in the health sector for the safety of neonates are essential. Such efforts are needed to curb the increase in premature infant mortality cases caused by bacteria, asphyxia, infections, and poor management of facility equipment. Furthermore, preterm and other at-risk babies have low ability to regulate temperature and produce body heat as characterized by their dry skin conditions; hence, the need for baby incubators. For their operation, these baby incubators provide strict regulated energy change that is influenced by heat transfer caused by the surrounding atmospheric temperature and humidity. This paper presents the design, construction, and performance study of a proposed Fuzzy-PID hybrid control system for regulating temperature and humidity in a baby incubator. To accomplish its goal, the proposed controller must be able to distribute heat and maintain humidity in the incubator under fluctuating atmospheric conditions to keep the baby’s body warm. Performance tests of the proposed hybrid controller were conducted by comparing temperature and humidity outputs in the baby incubator against predetermined expected values. Results show that the proposed controller is able to successfully achieve and maintain the temperature and humidity set points. Further examination also suggests that the proposed Fuzzy-PID hybrid control offers an improved overall system response performance compared to the PID controller.
A Brief Climatology of Dunkelflaute Events over and Surrounding the North and Baltic Sea Areas
Authors: Li Bowen , Basu Sukanta , Watson Simon J. , Russchenberg Herman W. J.
Published: October 2021

In the coming decades, the European energy system is expected to become increasingly reliant on non-dispatchable generation such as wind and solar power. Under such a renewable energy scenario, a better characterization of the extreme weather condition ‘Dunkelflaute’, which can lead to a sustained reduction of wind and solar power, is important. In this paper, we report findings from the very first climatological study of Dunkelflaute events occurring in eleven countries surrounding the North and Baltic Sea areas. By utilizing multi-year meteorological and power production datasets, we have quantified various statistics pertaining to these events and also identified their underlying meteorological drivers. It was found that almost all periods tagged as Dunkelflaute events (with a length of more than 24 h) are in November, December, and January for these countries. On average, there are 50–100 h of such events happening in each of these three months per year. The limited wind and solar power production during Dunkelflaute events is shown to be mainly driven by large-scale high-pressure systems and extensive low-cloud coverage. Even though the possibility of simultaneous Dunkelflaute events in neighboring countries can be as high as 30–40%, such events hardly occur simultaneously in all the eleven countries. Through an interconnected EU-11 power system, the mean frequency of Dunkelflaute drops from 3–9% for the individual countries to approximately 3.5% for the combined region, highlighting the importance of aggregating production over a wide area to better manage the integration of renewable energy generation.
Influence of Cold Water Inlets and Obstacles on the Energy Efficiency of the Hot Water Production Process in a Hot Water Storage Tank
Authors: Malec Agnieszka , Cholewa Tomasz , Siuta-Olcha Alicja
Published: October 2021

Domestic hot water preparation is one of the main sources of energy consumption in households. One of the most important elements of domestic hot water (DHW) preparation installation is the storage tank. Its design can significantly affect the efficiency of the system and energy consumption for hot water preparation. This paper presents the results of an experimental study to examine seven different designs of the cold water inlet to the storage tank and the use of two types of obstacles inside this tank placed at three different heights. The number of stratification and the energy efficiency of the system for each variant were examined. Additionally, tests were carried out for different profiles of hot water consumption in order to examine the temperature changes in the DHW tank. A system with an inlet, as an elbow facing down with a single plate, turned out to be the most advantageous variant (3–8% increase in energy efficiency compared to the basic inlet variant). An analogous analysis of the use of obstacles inside the tank showed that the most optimal solution is to place the partition, which allows the water flow on the sides of the tank, in its lower parts (energy efficiency higher by up to 15% compared to the variant without a partition). These solutions showed the highest energy efficiency for DHW production and the lowest energy demand for hot water heating in the tank among all analyzed variants.
Characteristics and Driving Factors of Rhizosphere Bacterial Communities of Chinese Fir Provenances
Authors: Yan Yao , Li Bingjun , Huang Zhijun , Zhang Hui , Wu Xiaojian , Farooq Taimoor Hassan , Wu Pengfei , Li Ming , Ma Xiangqing
Published: October 2021

Rhizosphere bacteria affect the diversity of soil functions, playing important roles in the growth and expansion of Chinese fir. Understanding the driving factors of rhizosphere bacterial distribution is imperative when comparing bacterial diversity and composition under different Chinese fir provenances. We investigated the growth of Chinese fir belts and the effects of climate, geographic location, and soil nutrients. Using 16S rDNA next-generation sequencing analysis, the bacterial communities of 16 Chinese fir provenances were compared. The bacterial compositionsof Dechang, Junlian, Shangrao, Zhenxiong, Yangxin, Xinyang, Luotian, and Tianmushan provenances weredistinct from others. Generally, higher-latitude provenances showed more biomarkers (LDA = 2). Rhizosphere bacterial α-diversity was the highest in Hunan Youxian and lowest in Henan Xinyang (p < 0.05). From south to north, bacterial α-diversity initially increased and then decreased. From east to west in the middle belt, bacterial α-diversity followed a “W” trend, with the eastern middle belt having the highest values, especially near Hunan, Fujian, and Zhejiang provinces. Amongst environmental factors, soil nutrient content (Mg, P and K) and stoichiometric ratio (Ca/Mg, K/Ca and N/P), along with precipitationrate primarily controlled rhizosphere bacterial diversity. Soil pH had a significant impact on the relative abundance of rhizosphere soil bacteria. Our findings offer insight into the evolution of Chinese fir and provide a scientific basis for soil microbial community improvement of Chinese fir provenances.
Alien Invasive Pathogens and Pests Harming Trees, Forests, and Plantations: Pathways, Global Consequences and Management
Authors: Panzavolta Tiziana , Bracalini Matteo , Benigno Alessandra , Moricca Salvatore
Published: October 2021

Forest health worldwide is impacted by many invasive alien pathogens and pests (IAPPs) that cause significant harm, with severe economic losses and environmental alterations. Destructive tree pathogens and pests have in the past devastated our forests, natural landscapes and cityscapes and still continue to represent a serious threat. The main driver of pathogen and pest invasions is human activities, above all global trade, which allows these invasive species to overstep their natural distribution ranges. While natural transport occurs according to a regular, expected colonization pattern (based on the dispersive capacity of the organism), human-mediated transport takes place on a larger, unpredictable scale. In order for a pathogen or pest species to become invasive in a new territory it must overcome distinct stages (barriers) that strongly affect the outcome of the invasion. Early detection is crucial to enabling successful eradication and containment. Although sophisticated diagnostic techniques are now available for disease and pest surveillance and monitoring, few control and mitigation options are usable in forestry; of these, biological control is one of the most frequently adopted. Since invasion by pathogens and pests is an economic and ecological problem of supranational relevance, governments should endorse all necessary preventive and corrective actions. To this end, establishing and harmonizing measures among countries is essential, both for preventing new introductions and for diminishing the eventual range expansion of IAPPs present at a local scale. Research is fundamental for: (i) developing effective and rapid diagnostic tools; (ii) investigating the epidemiology and ecology of IAPPs in newly introduced areas; and (iii) supporting policymakers in the implementation of quarantine regulations.
Correction: Bashir et al. Determinants of Nonindustrial Private Forest Owners’ Willingness to Harvest Timber in Norway. Forests 2020, 11, 60
Authors: Bashir Altamash , Sjølie Hanne K. , Solberg Birger
Published: October 2021

We have found some errors in our recently published article [...]
Characterizing Mode I Fracture Behaviors of Wood Using Compact Tension in Selected System Crack Propagation
Authors: Hu Wengang , Liu Yan , Li Shuang
Published: October 2021

The fracture behaviors of four wood species commonly used in wood products were characterized when subjected to compact tension (CT) load in radial-longitudinal (RL) system crack propagation. Meanwhile, the failure modes of evaluated CT samples were compared and analyzed using the fractal dimension method. The results showed that wood species had a significant effect on fracture characteristic values, including maximum fracture load, critical stress intensity factor and fracture energy. These characteristic values changed in the same way, i.e., beech wood CT samples obtained the maximum characteristic values, followed by ash, okoume, and poplar in descending order. The fracture behaviors of all wood species evaluated can be described by combining linear and exponential fitting equations at the crack initial stage and evolution stage, respectively. Linear positive proportional relationships were observed between fracture characteristic values and fractal dimensions calculated using cracks in front and left views of CT samples. However, the relationships between fracture characteristic values and fractal dimensions calculated using fracture surfaces were negative. The fractal dimensions of cracks in front view of CT samples could be a better indicator used to predict critical stress intensity factor and fracture energy, which had greater correlation coefficients beyond 0.95.
Improving Forest Baseline Maps in Tropical Wetlands Using GEDI-Based Forest Height Information and Sentinel-1
Authors: Verhelst Kamiel , Gou Yaqing , Herold Martin , Reiche Johannes
Published: October 2021

Remote Sensing-based global Forest/Non-Forest (FNF) masks have shown large inaccuracies in tropical wetland areas. This limits their applications for deforestation monitoring and alerting in which they are used as a baseline for mapping new deforestation. In radar-based deforestation monitoring, for example, moisture dynamics in unmasked non-forest areas can lead to false detections. We combined a GEDI Forest Height product and Sentinel-1 radar data to improve FNF masks in wetland areas in Gabon using a Random Forest model. The GEDI Forest Height, together with texture metrics derived from Sentinel-1 mean backscatter values, were the most important contributors to the classification. Quantitatively, our mask outperformed existing global FNF masks by increasing the Producer’s Accuracy for the non-forest class by 14%. The GEDI Forest Height product by itself also showed high accuracies but contained Landsat artifacts. Qualitatively, our model was best able to cleanly uncover non-forest areas and mitigate the impact of Landsat artifacts in the GEDI Forest Height product. An advantage of the methodology presented here is that it can be adapted for different application needs by varying the probability threshold of the Random Forest output. This study stresses that, in any application of the suggested methodology, it is important to consider the UA/PA trade-off and the effect it has on the classification. The targeted improvements for wetland forest mapping presented in this paper can help raise the accuracy of tropical deforestation monitoring.