bluuebunny/crossref_metadata_2025 huggingface dataset:
A Functional Safety Assessment Methodology for Explosion Protection with Application to a Variable Frequency Drive System
Authors: Li Shiguang , Wu Xiaojie
Published: November 2021

Modern explosion protection equipment, protected by traditional explosion protection technology (as defined by the international electrotechnical commission (IEC) publication IEC60079-ff series standards) and electrical/electronic/programmable electronic (E/E/PE) safety-related systems, is becoming ever more complex in coal mine development and petrochemical industry; thus, the possibility of failures in their operation is also growing. It is well-known that E/E/PE safety-related systems can be used to actively control dangerous sources, with real and expected levels of reliability, if they have been qualified according to the IEC61508-ff series standards. To uniformly evaluate the safety integrity level (SIL) of the explosion protection function of traditional explosion protection technology and E/E/PE safety-related system technology, this study analyzed the ability of these types of protection to remove the ignition risk residual, evaluating the failure rates of safety devices. The key objective of this paper is the presentation of a new equipment protection level (EPL) assessment method for explosion protection equipment based on a functional safety assessment. The method is applied to a variable frequency drive (VFD) system, and the results show that the EPL of the explosion protection equipment evaluated by this method is consistent with the EPL corresponding to the traditional explosion protection type of the IEC60079-ff series standard. Meanwhile, the flexible configuration of explosion protection safety devices and E/E/PE safety-related systems enables explosion protection equipment of different EPL levels to be designed.
Multichannel Detection of Acoustic Emissions and Localization of the Source with External and Internal Sensors for Partial Discharge Monitoring of Power Transformers
Authors: Búa-Núñez Iago , Posada-Román Julio E. , García-Souto José A.
Published: November 2021

The detection of acoustic emissions with multiple channels and different kinds of sensors (external ultrasound electronic sensors and internal optical fiber sensors) for monitoring power transformers is presented. The source localization based on the times of arrival was previously studied, comparing different strategies for solving the location equations and the most efficient strategy in terms of computational and complexity costs versus performance was selected for analyzing the error propagation. The errors of the acoustic emission source location (localization process) are evaluated from the errors of the times of arrival (detection process). A hybrid programming architecture is proposed to optimize both stages of detection and location. It is formed by a virtual instrumentation system for the acquisition, detection and noise reduction of multiple acoustic channels and an algorithms-oriented programming system for the implementation of the localization techniques (back-propagation and multiple-source separation algorithms could also be implemented in this system). The communication between both systems is performed by a packet transfer protocol that allows continuous operation (e.g., on-line monitoring) and remote operation (e.g., a local monitoring and a remote analysis and diagnosis). For the first time, delay errors are modeled and error propagation is applied with this error source and localization algorithms. The 1% mean delay error propagation gives an accuracy of 9.5 mm (dispersion) and a maximum offset of 4 mm (<1% in both cases) in the AE source localization process. This increases proportionally for more severe errors (up to 5% reported). In the case of a multi-channel internal fiber-optic detection system, the resulting location error with a delay error of 2% is negligible when selecting the most repeated calculated position. These aim at determining the PD area of activity with a precision of better than 1% (<10 mm in 110 cm).
Digital Technology Platforms as an Innovative Tool for the Implementation of Renewable Energy Sources
Authors: Bartczak Krzysztof
Published: November 2021

The subject matter addressed in the paper concerns digital technology platforms in the context of renewable energy sources. The main goal is to check whether digital technology platforms can be effective factors in implementing innovative business models in the RES sector. The study was based on empirical research using Computer-Assisted Telephone Interview (CATI) and Computer-Assisted Web Interview (CAWI) methods, as well as on a model of attitudes towards digital technology platforms (DTPs) built using CATREG (categorical regression) analysis. As a result of the research, it was found that digital technology platforms contribute to building innovative business models. The decisive influence on this is a number of benefits for enterprises and consumers (and the related factor is the most important when it comes to attitudes towards DTP), as well as the high interest in digital RES platforms.
Financial Balance Analysis of Geothermal Companies in Poland Based on Managerial Cash Flows
Authors: Kustra Arkadiusz , Lorenc Sylwia
Published: November 2021

The use of geothermal energy to produce heat and electricity has become increasingly important in recent years. This is mainly due to environmental issues and the need to ensure energy security. The aim of the article was to analyse and compare the ability to maintain cash balance of selected geothermal companies in Poland. The following were taken for verification: Przedsiębiorstwo Energetyki Cieplnej PEC Geotermia Podhalańska S.A., Geotermia Poddębice Sp. z o.o., Geotermia Mazowiecka S.A., Geotermia Pyrzyce Sp. z o.o. and Geotermia Czarnków Sp. z o.o. The adopted research methodology, combining accrual and cash recognition, allowed the analysis of the ability to create cash flows and maintain cash stability in 2016–2019. The study used financial data from the financial statements of the analysed companies. The analysis shows that the highest cash flows from assets defined as Free Cash Flow to Firm FCFF (over PLN 11,318 thousand) and the highest cash flows for owners Free Cash Flow to Equity FCFE (over PLN 10,005 thousand) are generated by Geotermia Mazowiecka S.A. At the same time, the balance between cash flows meeting the inequality FCFF ≥ FCFE + FCD, where FCD Free Cash Flow to Debt, determines the ability of assets to generate cash covering the current distribution of capital for its donors. Consequently, there is an increase in the value of cash resources identified in investments in the management balance sheet. Such a situation occurred in the case of Geotermia Poddębice Sp. z o.o. and Geotermia Mazowiecka S.A. The reverse situation, i.e., FCFF < FCFE + FCD is characteristic for cash imbalance. In such conditions there is a decrease in cash resources identified in the management balance. This occurred in PEC Geotermia Podhalańska S.A., Geotermia Pyrzyce Sp. z o.o. and Geotermia Czarnków Sp. z o.o.
Changes in the Stock Market of Food Industry Companies during the COVID-19 Pandemic—A Comparative Analysis of Poland and Germany
Authors: Kacperska Elżbieta , Kraciuk Jakub
Published: November 2021

The COVID-19 pandemic had a dramatic effect on the world economy, leading to disturbances in the global agri-food system. Disrupted supply chains caused instability in the market resulting in mixed reactions among market participants. The balance in the access and availability of food was disturbed at various levels starting from local up to international. Partial lockdowns of economies affected the equilibrium on the labor market in the food sector, the level of income and food security. The aim of this study was to determine the effect of shock caused by the COVID-19 pandemic on rates of return from shares of companies in the agri-food sector listed in Poland and Germany, as well as indicate dependencies between restrictions imposed by the investigated countries and changes in the rates of return from shares as a result of the pandemic. The source of data for the analyses of the capital markets in Poland and Germany was the Thomson Reuters database. In order to determine the effect of shock caused by the coronavirus pandemic and restrictions imposed by the states on the capital market the abnormal rates of return were calculated for shares of 24 Polish and 23 German companies from the food sector. The investigated Polish companies were listed on the Warsaw Stock Exchange, while the German companies were listed on the Frankfurt Stock Exchange and other stock exchanges in Germany. Calculations were based on stock market indexes: for the Polish stock exchange it was WIG and WIG-food, while for the German capital market it was DAX and DAX Food & Beverages. In this study the Stringency Index was also used as a tool to follow the response of the governments to the coronavirus pandemic. The results indicate that following the pandemic outbreak large reductions were observed for cumulative rates of return from shares as a consequence of the pandemic both in Poland and Germany. Abnormal cumulative rates of return for the investigated companies were comparable. Markedly greater increases in abnormal rates of return were recorded for the Polish companies of the food sector listed at the Warsaw Stock Exchange. The Stringency Index indicates that restrictions imposed by the German authorities in response to the coronavirus pandemic were slightly more radical than those introduced by the Polish government.
A Review of Active Aerodynamic Systems for Road Vehicles
Authors: Piechna Janusz
Published: November 2021

Comfort, safety, high travel speeds, and low fuel consumption are expected characteristics of modern cars. Some of these are in conflict with one other. A solution to this conflict may be time-varying body geometry realized by moving aerodynamic elements and appropriate systems for controlling their motion. This paper presents a review of existing technical solutions and the results of published research on the effects of active flow control around a vehicle on its dynamic properties. Active aerodynamic systems typically adjust certain aerodynamic characteristics based on the vehicle speed, but systems using other information such as acceleration, yaw rate, steering angle, and brake pressure, as well as fully automatic systems, are also considered. This review provides information on historical and current methods, models, and their effectiveness in designing vehicle bodies and the movable aerodynamic elements mounted on them. Technical solutions in which the driver is an element of the control system, automatic systems, their models, models of movable aerodynamic elements, and coupled dynamic-aerodynamic models are presented. A number of types of moving aerodynamic element solutions used for different purposes are considered in this paper and conclusions are presented.
Self-Consumption and Self-Sufficiency Improvement for Photovoltaic System Integrated with Ultra-Supercapacitor
Authors: Hassan Qusay , Jaszczur Marek
Published: November 2021

This research study uses a computer simulation based on real input data to examine the impact of a supercapacitor module working as a fast response energy storage unit in renewable energy systems to increase energy self-consumption and self-sufficiency. The evaluated system includes a photovoltaic system with a capacity of 3.0 kWp and between 0 and 5 supercapacitor units with a capacity of 500 F per module. The study was carried out using experimental data for electrical load, solar irradiance, and ambient temperature for the year 2020, with a 1 min temporal resolution. The daily average ambient temperature was 10.7 °C, and the daily average solar irradiance was 3.1 kWh/m2/day. It is assumed that the supercapacitor could only be charged from a photovoltaic system using renewable energy and not from the grid. The simulation results showed that using the supercapacitors to feed the short and large peaks of the electrical load significantly increases energy self-consumption and self-sufficiency. With only five supercapacitor modules, yearly energy self-sufficiency increases from 28.09% to 40.77%.
Wave Energy Converter’s Slack and Stiff Connection: Study of Absorbed Power in Irregular Waves
Authors: Potapenko Tatiana , Burchell Joseph , Eriksson Sandra , Temiz Irina
Published: November 2021

Two different concepts of wave energy converter coupled to the novel C-GEN linear generator have been studied numerically, including the evaluation of different buoy sizes. The first concept has a slack connection between the buoy and the generator on the seabed. Another concept is based on a stiff connection between the buoy and the generator placed on an offshore platform. Three different approaches to calculate the damping force have been utilized within this study: the optimal damping coefficient, R-load, and RC-load. R-load is a model for the load applied to a grid-connected generator with passive rectification. RC-load is a model for a phase angle compensation applied to a system with active rectification. The radiation forces originating from the oscillatory motion of the buoy have been approximated using the transfer function in the frequency domain and the vector fitting algorithm. A comparison of the approximation methods is presented, and their accuracy has been evaluated. The advantage of the vector fitting method has been shown, especially for higher approximation orders which fit the transfer function with high accuracy. The study’s final results are shown in terms of the absorbed power for the sea states of March 2018 at Wave Hub, UK.
Testing of Conductive Carbon Fiber Reinforced Polymer Composites Using Current Impulses Simulating Lightning Effects
Authors: Filik Kamil , Karnas Grzegorz , Masłowski Grzegorz , Oleksy Mariusz , Oliwa Rafał , Bulanda Katarzyna
Published: November 2021

Carbon fiber reinforced polymer (CFRP) composites are lightweight and an increasingly used material with good mechanical properties. In the aviation industry, they are also required to have specific electrical properties that guarantee resistance to the direct and indirect lightning effects. The paper is focused on the description of a test stand and development of a method used to determine the electrical characteristics of conductive CFRP laminate samples with the use of high current impulses of lightning nature. Samples of three laminates (square format with side 30 × 30 cm) with a different composition were tested on the constructed stand, confirming the possibility of characterizing this type of laminate sample in terms of electrical conductivity and resistance to the effects of lightning current. It was possible to observe the impulse current flow (with a peak value up to 15 kA and a rise time above 6 µs) from the high voltage electrode placed in the center of the sample in all directions towards the edge. The optical fiber measuring system was used to record the voltage and current time waveforms. The energy stored in the impulse current generator was sufficient to simulate the mechanical damage, such as burnout and delamination, that accompanies the direct lightning strike to structural elements made of CFRP. The influence of the matrix composition used for laminate fabrication on the test results describing the electrical properties of the tested CFRP samples was noted. The experimental setup allows the testing of specimens with a maximum width and length of 50 × 50 cm and any thickness with a peak current of up to 50 kA.
The Leading Traits of the Modern Corporate Leader: Comparing Survey Results from 2008 and 2018
Authors: Karaszewski Robert , Drewniak Rafał
Published: November 2021

This article deals with the evolution of leadership in the corporate business environment by presenting the results of comparative empirical studies conducted in 2008 and 2018. Based on an analysis of empirical research on the 2000 largest global corporations, obtained from the Forbes Global 2000, this work presents the changes that took place over a decade in the characteristics and competencies of contemporary leaders. The results allowed us to identify the desired characteristics, competencies, and character traits of contemporary leaders. In fact, the comparative analysis of these data showed the dynamics of change in the approach of global corporate leaders over the decade. The research results have important implications for the energy sector. Some of the companies participating in the study operate in the energy sector, therefore the opinions of these CEOs indicate significant determinants of modern leadership in this type of enterprise. When analysing the research results on the vision and scope of leadership impact in corporate business, we pointed, among other things, to the assessment of leadership traits, the evolution of leadership activities’ delegation, and the assessment of the importance of managers’ individual action areas and leadership factors.
Utilization of Thermally Activated Building System with Horizontal Ground Heat Exchanger Considering the Weather Conditions
Authors: Chung Woong , Park Sang
Published: November 2021

The thermally activated building system (TABS) can reduce the peak load by integrating with the ground heat exchangers. When integrated, the cost of groundwork and stability of the ground temperature would counteract because the weather conditions would influence the ground temperature in shallow depth. However, previous studies on TABS assumed constant ground temperatures such as average outdoor air temperature. In this study, ground temperatures in different depths are simulated for their detailed investigations, and simulated results of ground temperature were applied to building energy simulations for observing the load-handled ratio (LHR), representing the peak load reduction by TABS evaluated in various weather conditions. Simulation results of ground temperatures from 1 m to 39 m depths show that the temperature stabilized at 2 m to 11 m depths depending on the characteristics of the outdoor air temperature. LHR increased as the ground depth increased because the ground temperature at shallow depths increased during peak hours. Ground depths of 8 m were found ideal for maintaining consistent LHR for all weather conditions. Detailed observation of ground temperature and its effect on LHR in various weather conditions can help system engineers design and operate the TABS with the ground system.
Sustainable Materials from Fish Industry Waste for Electrochemical Energy Systems
Authors: Lionetto Francesca , Bagheri Sonia , Mele Claudio
Published: November 2021

Fish industry waste is attracting growing interest for the production of environmentally friendly materials for several different applications, due to the potential for reduced environmental impact and increased socioeconomic benefits. Recently, the application of fish industry waste for the synthesis of value-added materials and energy storage systems represents a feasible route to strengthen the overall sustainability of energy storage product lines. This review focused on an in-depth outlook on the advances in fish byproduct-derived materials for energy storage devices, including lithium-ion batteries (LIBs), sodium-ion (NIBs) batteries, lithium-sulfur batteries (LSBs), supercapacitors and protein batteries. For each of these, the latest applications were presented together with approaches to improve the electrochemical performance of the obtained materials. By analyzing the recent literature on this topic, this review aimed to contribute to further advances in the sustainability of energy storage devices.
Rethinking the Distribution Power Network Planning and Operation for a Sustainable Smart Grid and Smooth Interaction with Electrified Transportation
Authors: Soares Joao , Canizes Bruno , Vale Zita
Published: November 2021

This editorial document provides the main motivations and a brief description of each paper published in the “Rethinking the Distribution Power Network Planning and Operation for a Sustainable Smart Grid and Smooth Interaction with Electrified Transportation” Special Issue. This Special Issue aims to present several innovative solutions on planning and operation of distribution power networks under smart grid paradigm where prosumers, electric vehicles, and other typical loads are usually connected. Some of those solutions and computational applications were covered in this Special Issue, namely probabilistic power flow, voltage and power factor control, agent-based simulation, digital twin, resilient energy scheduling, and uncertainty modeling are among the contributions. The published works are very timely and are of great interest, which will certainly drive the impact of future researchers in the near term concerning the field of this Special Issue.
Income Maximisation in a Maltese Household Photovoltaic System by Means of Output and Consumption Simulations
Authors: Zingariello Daniele , Demicoli Marija , Stagno Luciano Mule’
Published: November 2021

The installation of photovoltaic (PV) systems in the Maltese Islands plays an important role in allowing Malta to increase its share in renewable energy to meet the set European Union targets. In the Maltese residential sector, PV systems are generally installed on rooftops of households with a south-facing orientation and a 30° inclination angle. The scope of this study is to present a methodology to maximise the income for residents from electricity generated, by comparing the output of electricity generation with the electricity consumption patterns of different household types and consequently identifying the most favourable installation configurations of these PV systems. The research was carried out by simulating the monthly electricity generation of a 3 kilowatt-peak PV system for a year, as well as the hourly electricity generation for a day in each season of the year using the PVsyst software package. A total of 21 configurations were studied by altering the orientation and inclination angles used to install the PV system. This study confirms that a south-facing PV system inclined at 30° generates the most electricity in a year. However, when compared with electricity consumption patterns of low-, medium- and high-consumption households, it is shown that a south-facing PV system inclined at 40° provides a better income for residents.
Design and Assessment of ADRC-Based Autopilot for Energy-Efficient Ship Steering
Authors: Zwierzewicz Zenon , Dorobczyński Lech , Artyszuk Jarosław
Published: November 2021

This paper looks at a typical problem encountered in the process of designing an automatic ship’s course stabilisation system with the use of a relatively new methodology referred to as the Active Disturbance Rejection Control (ADRC). The main advantage of this approach over classic autopilots based on PID algorithms, still in the majority, is that it eliminates the tuning problem and, thus, ensures a much better average performance of the ship in various speed, loading, nautical and weather conditions during a voyage. All of these factors call for different and often dynamically variable autopilot parameters, which are difficult to assess, especially by the ship’s crew or owner. The original result of this article is that the required controller parameters are approximated based on some canonical model structure and analysis of the hydrodynamic properties of a wide class of ships. Another novelty is the use of a fully verified, realistic numerical hydrodynamic model of the ship as a simulation model as well as a basis for deriving a simplified model structure suitable for controller design. The preliminary results obtained indicate good performance of the proposed ADRC autopilot and provide prospects for its successful implementation on a real ship.
The Influence of Pantograph Carbon–Metal Composite Slider Thermal Properties on the Railroad Wire Temperature
Authors: Mańka Adam , Hełka Andrzej , Ćwiek Janusz
Published: November 2021

This article presents the methodology, description, and results of experimental studies aimed at determining the impact of the copper concentration in a carbon–metal composite contact strip on the maximum temperature of the copper contact wire during a contact event when used for operation in the railway industry in Europe. Based on these tests, we determined the minimum percentage of copper that is required for the composite to meet the normative requirements for current loads. In addition to experimental research, a 3D FEM numerical model was also developed in which the contact strip and contact wire geometry were mapped, along with imposed loads resulting from the test for current loads mentioned above. Fifteen simulation variants were carried out for the established model, where the value of the thermal conductivity coefficient and the specific heat coefficient were varied. On this basis, we analyzed the sensitivity of thermal coefficients to the contact wire temperature and determined the minimum conductivity coefficient value, which allowed the maximum copper contact wire temperature of 120 °C to be obtained during the verification tests.
Short-Term Forecasting of Wind Energy: A Comparison of Deep Learning Frameworks
Authors: Mora Elianne , Cifuentes Jenny , Marulanda Geovanny
Published: November 2021

Wind energy has been recognized as the most promising and economical renewable energy source, attracting increasing attention in recent years. However, considering the variability and uncertainty of wind energy, accurate forecasting is crucial to propel high levels of wind energy penetration within electricity markets. In this paper, a comparative framework is proposed where a suite of long short-term memory (LSTM) recurrent neural networks (RNN) models, inclusive of standard, bidirectional, stacked, convolutional, and autoencoder architectures, are implemented to address the existing gaps and limitations of reported wind power forecasting methodologies. These integrated networks are implemented through an iterative process of varying hyperparameters to better assess their effect, and the overall performance of each architecture, when tackling one-hour to three-hours ahead wind power forecasting. The corresponding validation is carried out through hourly wind power data from the Spanish electricity market, collected between 2014 and 2020. The proposed comparative error analysis shows that, overall, the models tend to showcase low error variability and better performance when the networks are able to learn in weekly sequences. The model with the best performance in forecasting one-hour ahead wind power is the stacked LSTM, implemented with weekly learning input sequences, with an average MAPE improvement of roughly 6, 7, and 49%, when compared to standard, bidirectional, and convolutional LSTM models, respectively. In the case of two to three-hours ahead forecasting, the model with the best overall performance is the bidirectional LSTM implemented with weekly learning input sequences, showcasing an average improved MAPE performance from 2 to 23% when compared to the other LSTM architectures implemented.
Low-Cost Air-Cooling System Optimization on Battery Pack of Electric Vehicle
Authors: Widyantara Robby Dwianto , Naufal Muhammad Adnan , Sambegoro Poetro Lebdo , Nurprasetio Ignatius Pulung , Triawan Farid , Djamari Djati Wibowo , Nandiyanto Asep Bayu Dani , Budiman Bentang Arief , Aziz Muhammad
Published: November 2021

Temperature management for battery packs installed in electric vehicles is crucial to ensure that the battery works properly. For lithium-ion battery cells, the optimal operating temperature is in the range of 25 to 40 °C with a maximum temperature difference among battery cells of 5 °C. This work aimed to optimize lithium-ion battery packing design for electric vehicles to meet the optimal operating temperature using an air-cooling system by modifying the number of cooling fans and the inlet air temperature. A numerical model of 74 V and 2.31 kWh battery packing was simulated using the lattice Boltzmann method. The results showed that the temperature difference between the battery cells decreased with the increasing number of cooling fans; likewise, the mean temperature inside the battery pack decreased with the decreasing inlet air temperature. The optimization showed that the configuration of three cooling fans with 25 °C inlet air temperature gave the best performance with low power required. Even though the maximum temperature difference was still 15 °C, the configuration kept all battery cells inside the optimum temperature range. This finding is helpful to develop a standardized battery packing module and for engineers in designing low-cost battery packing for electric vehicles.
Ammonia Recovery from Digestate Using Gas-Permeable Membranes: A Pilot-Scale Study
Authors: Riaño Berta , Molinuevo-Salces Beatriz , Vanotti Matías B. , García-González María Cruz
Published: November 2021

The reduction and recovery of nitrogen (N) from anaerobically digested manure (digestate) is desirable to mitigate N-related emissions, mainly ammonia and nitrate, derived from digestate land application in nutrient-saturated zones. This work reports the results of a gas-permeable membrane (GPM) pilot-scale plant to recover ammonia from digestate in the framework of the EU project Ammonia Trapping. The total ammonia nitrogen (TAN) concentration in digestate was reduced by 34.2% on average (range 9.4–57.4%). The recovery of TAN in the trapping solution in the form of a (NH4)2SO4 solution averaged 55.3% of the removed TAN, with a TAN recovery rate of 16.2 g N m−2 d−1 (range between 14.5 and 21.0 g N m−2 d−1). The TAN concentration in the trapping solution achieved a value of up to 35,000 mg N L−1. The frequent change of the trapping solution has been proven as an efficient strategy to improve the overall performance of the GPM technology.
Fuelwood Harvest and No Harvest Effects on Forest Composition, Structure, and Diversity of Arasbaran Forests—A Case Study
Authors: Ghanbari Sajad , Kern Christel C.
Published: November 2021

The impact of fuelwood harvesting on forest structure and composition is not clear, especially on the understudied and scarce Arasbaran forests in Iran. This research compared woody species density, species diversity, forest composition, and regeneration status in areas of continuous and ceased fuelwood harvesting in Arasbaran forests. We expected fuelwood harvesting to decrease stem density, species diversity, tree size (diameter at the breast height (DBH) and height), and shift composition away from preferred fuelwood species. We measured woody species size and frequency and identified species in three fuelwood harvest and three no harvest sites, with six sample plots (100 m × 50 m) per site. Results tended to show differences in composition, diversity, woody species height, and density. Carpinus orientalis, a preferred fuelwood species, tended to be more dominant in no harvest (importance values index (IVI) = 173.4) than harvest areas (IVI = 4.4). The diversity or richness of woody species tended to be higher in harvest (20 ± 1 species per ha) than in no harvest (14 ± 2 species per ha) areas, and other measures of diversity supported this trend as well. Harvest areas tended to also be characterized by shorter tree height and lower density of trees, a higher density of regeneration, and fewer small pole-sized trees than no harvest areas. Ongoing fuelwood harvests may further shift composition and structure away from no harvest area, compromising future fuelwood availability, but further detailed research is needed. Close to nature practices may be useful in sustaining fuelwood harvest areas and diversifying areas where fuelwood harvesting has ceased.
Drivers of Spatial Heterogeneity in the Russian Forest Sector: A Multiple Factor Analysis
Authors: Gordeev Roman V. , Pyzhev Anton I. , Yagolnitser Miron A.
Published: November 2021

This study explored the regional differences in the forest industry and management via a Multiple Factor Analysis approach. The dataset used comprises all Russian regions and 34 variables that comprehensively describe the situation in the sector. Based on the Multiple Factor Analysis, the variables contributing most to the spatial heterogeneity in Russian forestry were divided into industrial and forestry factors. The regions leading in the development of the timber industry are mainly located in the Northwestern and Southeastern parts of Russia. They show similarities in high logging volumes, investment attractiveness, and competitiveness in foreign markets. However, a divergence was found between the Northwestern regions and the Siberian and the Far East territories in terms of forest management factors. The Western part of Russia benefits from the density of the population and infrastructure, and proximity to the national financial centers and European markets. By comparison, Asian Russia suffers from labor shortages caused by negative demographic trends and the negative consequences of climate change, resulting in an increase in forest losses and a lack of control, finance, and transport accessibility due to the vast territory. To alleviate regional inequalities, we propose the introduction of private ownership of forests, support for investment projects, and human capital development.
Plant Tannins and Essential Oils Have an Additive Deterrent Effect on Diet Choice by Kangaroos
Authors: Rafferty Christine , Lamont Byron B.
Published: November 2021

Tannins and essential oils are well recognised as antiherbivore compounds. We investigated the relative effectiveness of the polyphenol, tannin, and the essential oils, 1,8-cineole and pine oil, as feeding deterrents against western grey kangaroos. Both groups of secondary metabolites are naturally abundant in many Australian plants. These three metabolite groups were incorporated separately or together into standard pellets for presentation to kangaroos, and their behaviour (sequence of food choice and feeding time) and amounts consumed were observed. The control (with no secondary metabolites) was much preferred. There was a sharp reduction in the ingestion of pellets containing tannins, 1,8-cineole or pine oil. Combinations of the metabolites resulted in almost no consumption. In association with tannin, pellets containing either 1,8-cineole or pine oil were as effective deterrents as both combined. There was a strong correlation between time spent feeding on the different diets and the amount of food consumed, although the rate of intake was markedly slower when secondary metabolites were present. Behavioural observations showed that the amount of food ingested is initially guided by the presence/absence of essential oils, apparently detected by smell, and later by the presence/absence of tannins, by taste. Both groups of secondary metabolites work in concert by stimulating different senses that minimise herbivory by marsupials, such as the western grey kangaroo, and help to explain their abundance in the Australian flora.
Exploring Correlation between Stand Structural Indices and Parameters across Three Forest Types of the Southeastern Italian Alps
Authors: Alterio Edoardo , Cislaghi Alessio , Bischetti Gian Battista , Sitzia Tommaso
Published: November 2021

Forest stand structure can be described through stand structural parameters as well as using stand structural indices. However, to date, there is still much uncertainty regarding how stand structural indices and parameters are intercorrelated. The analysis of correlation can guide their selection in research applications and forest management, avoiding redundancies and loss of time during data collection. In this study, using a sample of forest stands belonging to three forest types of the southeastern Italian Alps, we explored the correlation among stand structural indices, and then we checked the relationships between stand structural indices and stand structural parameters. The results indicate that the stand structural indices vary among the sampled forest types. Moreover, the correlation among stand structural indices indicates that some of them are strongly intercorrelated and, thus, they can give redundant information. Strong correlations have been found between the Shannon index and the Mingling index, between the Gini index and the Diameter differentiation index, and between size dominance indices. Correlations between stand structural indices and stand structural parameters were weak, and, therefore, we cannot recommend the exclusive use of stand structural indices as alternative to the common stand structural parameters. Instead, the combined use of stand structural indices and parameters can be a robust solution for describing forest stand structure.
Determination of the Chemical Composition of Eucalyptus spp. for Cellulosic Pulp Production
Authors: Vieira Túlio Anselmo Sacramento , Arriel Taiana Guimarães , Zanuncio Antônio José Vinha , Carvalho Amélia Guimarães , Branco-Vieira Monique , Carabineiro Sónia Alexandra Correia , Trugilho Paulo Fernando
Published: November 2021

The chemical composition of wood is important to assess the quality of this raw material for the industry of cellulosic pulp production. The purpose of this work was to determine the chemical composition of Eucalyptus spp. grown for cellulosic pulp production. Ten Eucalyptus spp. clones with six years of age, located in the municipality of Itamarandiba, Minas Gerais, Brazil, were used. Quantification was obtained for extractives, monosaccharides, uronic acids, acetates, lignin, ash and the phenolic composition of the extracts. In average, clones showed around 2.7% extractives, with a predominance of polar compounds soluble in ethanol and water; 27.7% lignin and 0.3% ash. Glucose was the main sugar detected (64.2%), followed by xylose (19.3%). The main components of the extractives were steroids, fatty acids and aromatic acids, followed by smaller amounts of substituted alkanoic acids, fatty alcohols, glycerol derivatives and triterpenes. The ethanol–water extracts presented total phenol contents ranging from 321.4 to 586.6 mg EAG/g of extract, tannins from 28.1 to 65.1 mg catechin/g of extract and flavonoids from 73.6 to 256.9 mg catechin/g of extract. Clones with a higher holocellulose amount and a lower lignin content showed a higher potential for cellulosic pulp production. These findings are important for the development of high-quality wood based on important traits for the pulp and paper sector.
Exploring the Outdoor Recreational Behavior and New Environmental Paradigm among Urban Forest Visitors in Korea, Taiwan and Indonesia
Authors: Kim Doyeon , Avenzora Ricky , Lee Ju-hyoung
Published: November 2021

This is international comparative research on the perception of local residents toward the natural environment in South Korea, Taiwan, and Indonesia. Through the New Ecological Paradigm (NEP) investigation, perceptions of natural environmental conservation and utilization of 664 urban forest visitors were analyzed, and the relationship between recreational behavior, NEP scores, and demographic characteristics was investigated. The three countries, with different histories, cultures, and economic development, showed statistically significant differences in all items. In terms of the NEP response score, Taiwan showed the most positive results with an average of 4.08. Frequent visits by the elderly and family were common significant factors of high NEP score for all survey locations. In the confirmatory factor analysis of latent variables for NEP, ‘limits to growth’ were significant in South Korea while ‘ecological crisis’ was more significant in Taiwan and Indonesia. Forest experience frequency was a common factor affecting NEP, indicating that frequent forest visits during leisure time are a major factor in improving the ecological paradigm.
Improving the Robustness of Model Compression by On-Manifold Adversarial Training
Authors: Kwon Junhyung , Lee Sangkyun
Published: November 2021

Despite the advance in deep learning technology, assuring the robustness of deep neural networks (DNNs) is challenging and necessary in safety-critical environments, including automobiles, IoT devices in smart factories, and medical devices, to name a few. Furthermore, recent developments allow us to compress DNNs to reduce the size and computational requirements of DNNs to fit them into small embedded devices. However, how robust a compressed DNN can be has not been well studied in addressing its relationship to other critical factors, such as prediction performance and model sizes. In particular, existing studies on robust model compression have been focused on the robustness against off-manifold adversarial perturbation, which does not explain how a DNN will behave against perturbations that follow the same probability distribution as the training data. This aspect is relevant for on-device AI models, which are more likely to experience perturbations due to noise from the regular data observation environment compared with off-manifold perturbations provided by an external attacker. Therefore, this paper investigates the robustness of compressed deep neural networks, focusing on the relationship between the model sizes and the prediction performance on noisy perturbations. Our experiment shows that on-manifold adversarial training can be effective in building robust classifiers, especially when the model compression rate is high.
Blockchain and Self Sovereign Identity to Support Quality in the Food Supply Chain
Authors: Cocco Luisanna , Tonelli Roberto , Marchesi Michele
Published: November 2021

This work presents how a digital identity management system can support food supply chains in guaranteeing the quality of the products marketed and the compliance of the several supply-chain’s nodes to standards and technical regulations. Specific goal of this work is to present a system that provides full visibility of process/food certifications, which nowadays are issued by accredited and approved certification bodies (issuers) and delivered and stored in paper version by the several participants (holders) of the supply chain. The system is designed and implemented by combining the latest most innovative and disruptive technologies in the market—Self Sovereign Identity system, Blockchain, and Inter Planetary File System. The crucial aspects that it aims to hit are the storage and access of food/process certifications, and the proper eligibility verification of these certifications exploiting the concepts of the Self Sovereign Identity-based models. The proposed system, realized by using standards that are WWW Consortium-compatible and the Ethereum Blockchain, ensures eligibility, transparency, and traceability of the certifications along a food supply chain, and could be an innovation model/idea that the companies that adopt the Open Innovation paradigm might want to pursue.
Two-Dimensional Steady Boussinesq Convection: Existence, Computation and Scaling
Authors: Lane Jeremiah S. , Akers Benjamin F.
Published: November 2021

This research investigates laser-induced convection through a stream function-vorticity formulation. Specifically, this paper considers a solution to the steady Boussinesq Navier–Stokes equations in two dimensions with a slip boundary condition on a finite box. A fixed-point algorithm is introduced in stream function-vorticity variables, followed by a proof of the existence of steady solutions for small laser amplitudes. From this analysis, an asymptotic relationship is demonstrated between the nondimensional fluid parameters and least upper bounds for laser amplitudes that guarantee existence, which accords with numerical results implementing the algorithm in a finite difference scheme. The findings indicate that the upper bound for laser amplitude scales by O(Re−2Pe−1Ri−1) when Re≫Pe, and by O(Re−1Pe−2Ri−1) when Pe≫Re. These results suggest that the existence of steady solutions is heavily dependent on the size of the Reynolds (Re) and Peclet (Pe) numbers, as noted in previous studies. The simulations of steady solutions indicate the presence of symmetric vortex rings, which agrees with experimental results described in the literature. From these results, relevant implications to thermal blooming in laser propagation simulations are discussed.
Optimization of a Grid-Connected Microgrid Using Tidal and Wind Energy in Cook Strait
Authors: Majdi Nasab Navid , Islam Md Rabiul , Muttaqi Kashem , Sutanto Danny
Published: November 2021

The Cook Strait in New Zealand is an ideal location for wind and tidal renewable sources of energy due to its strong winds and tidal currents. The integration of both technologies can help to avoid the detrimental effects of fossil fuels and to reduce the cost of electricity. Although tidal renewable sources have not been used for electricity generation in New Zealand, a recent investigation, using the MetOcean model, has identified Terawhiti in Cook Strait as a superior location for generating tidal power. This paper investigates three different configurations of wind, tidal, and wind plus tidal sources to evaluate tidal potential. Several simulations have been conducted to design a DC-linked microgrid for electricity generation in Cook Strait using HOMER Pro, RETScreen, and WRPLOT software. The results show that Terawhiti, in Cook Strait, is suitable for an offshore wind farm to supply electricity to the grid, considering the higher renewable fraction and the lower net present cost in comparison with those using only tidal turbines or using both wind and tidal turbines.
Flow Dynamics in a Model of a Left Ventricle with Different Mitral Valve Orientations
Authors: Maraouch Ghassan , Kadem Lyes
Published: November 2021

The formation of vortex rings at valve leaflets during ventricular inflow has been a topic of interest for many years. It is generally accepted nowadays that the purpose of vortex rings is to conserve energy, reduce the workload on the heart, and minimize particle residence time. We investigated these claims by testing three different levels of annulus angle for the mitral valve: a healthy case, a slightly angled case (20°), and a highly angled case (46°). Circulation was determined to be reversed in the non-healthy case, with a dominant counterclockwise rotation instead of clockwise. Viscous energy dissipation was highest in the slightly angled case, followed by the healthy case and then the highly angled case. A Lagrangian analysis demonstrated that the healthy case resulted in the least amount of stasis, requiring eight cardiac cycles to evacuate 99% of initial ventricle volume compared to the 16 and 13 cardiac cycles required by the slightly angled and highly angled cases, respectively.
Tomographic Particle Image Velocimetry and Dynamic Mode Decomposition (DMD) in a Rectangular Impinging Jet: Vortex Dynamics and Acoustic Generation
Authors: Assoum Hassan H. , Hamdi Jana , Alkheir Marwan , Abed Meraim Kamel , Sakout Anas , Obeid Bachar , El Hassan Mouhammad
Published: November 2021

Impinging jets are encountered in ventilation systems and many other industrial applications. Their flows are three-dimensional, time-dependent, and turbulent. These jets can generate a high level of noise and often present a source of discomfort in closed areas. In order to reduce and control such mechanisms, one should investigate the flow dynamics that generate the acoustic field. The purpose of this study is to investigate the flow dynamics and, more specifically, the coherent structures involved in the acoustic generation of these jets. Model reduction techniques are commonly used to study the underlying mechanisms by decomposing the flow into coherent structures. The dynamic mode decomposition (DMD) is an equation-free method that relies only on the system’s data taken either through experiments or through numerical simulations. In this paper, the DMD technique is applied, and the spatial modes and their frequencies are presented. The temporal content of the DMD’s modes is then correlated with the acoustic signal. The flow is generated by a rectangular jet impinging on a slotted plate (for a Reynolds number Re = 4458) and its kinematic field is obtained via the tomographic particle image velocimetry technique (TPIV). The findings of this research highlight the coherent structures signature in the DMD’s spectral content and show the cross correlations between the DMD’s modes and the acoustic field.