bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis and Design of Three-Phase LLC Resonant Converter with Matrix Transformers
Authors: Lin Jing-Yuan , Yueh Hsuan-Yu , Lin Yi-Feng , Liu Pin-Hsien
Published: February 2022

This study presents the topology of a three-phase LLC resonant converter with matrix transformers. The three-phase LLC resonant converter has the advantages of conventional LLC resonant converters, including zero-voltage switching at the primary side, zero-current switching at the secondary side, high-frequency feasibility, and high efficiency. Moreover, it has additional advantages that differ from conventional LLC, including low output capacitor current ripple, natural current sharing in three resonant currents, and a high power level. As a result of the above mentioned characteristics, LLC topology has been used in many electric vehicle charging systems, server power systems, and other high-power applications. However, as the power level becomes higher and higher, the input voltage is usually too high to reduce conduction loss, and the output current also increases. This situation makes transformer design more difficult. The increasing current means more core and copper loss, and the heat dissipation of the transformer becomes more difficult. Matrix transformer technology can improve this problem directly and simply. By utilizing matrix transformers, which are primary series connected and secondary parallel connected, the primary voltage stress and secondary current stress of the transformers can be reduced, and the output current can be distributed. The analysis of the proposed converter in this study includes a circuit operation introduction, a time-domain analysis, calculation of the transfer ratio curve in the frequency domain, and a loss analysis. The theoretical analysis and performance of the proposed converter are verified. A three-phase LLC resonant converter with matrix transformers prototype is built with a high input voltage of 800-VDC and high output current of 200-A. The output voltage is 100-VDC. The waveform and efficiency data will be shown in the experimental results.
Planning and Operational Aspects of Individual and Clustered Multi-Energy Microgrid Options
Authors: Kostelac Matija , Herenčić Lin , Capuder Tomislav
Published: February 2022

With the restructuring of the power system, household-level end users are becoming more prominent participants by integrating renewable energy sources and smart devices and becoming flexible prosumers. The use of microgrids is a way of aggregating local end users into a single entity and catering for the consumption needs of shareholders. Various microgrid architectures are the result of the local energy community following different decarbonisation strategies and are frequently not optimised in terms of size, technology or other influential factors for energy systems. This paper discusses the operational and planning aspects of three different microgrid setups, looking at them as individual market participants within a local electricity market. This kind of implementation enables mutual trade between microgrids without additional charges, where they can provide flexibility and balance for one another. The developed models take into account multiple uncertainties arising from photovoltaic production, day-ahead electricity prices and electricity load. A total number of nine case studies and sensitivity analyses are presented, from daily operation to the annual planning perspective. The systematic study of different microgrid setups, operational principles/goals and cooperation mechanisms provides a clear understanding of operational and planning benefits: the electrification strategy of decarbonising microgrids outperforms gas and hydrogen technologies by a significant margin. The value of coupling different types of multi-energy microgrids, with the goal of joint market participation, was not proven to be better on a yearly level compared to the operation of same technology-type microgrids. Additional analyses focus on introducing distribution and transmission fees to an MG cooperation model and allow us to come to the conclusion of there being a minor impact on the overall operation.
Numerical Feasibility Study of Self-Regulating Radiant Ceiling in Combination with Diffuse Ceiling Ventilation
Authors: Krusaa Marie Rugholm , Hviid Christian Anker
Published: February 2022

A focus on indoor comfort and tightening targets for energy savings in buildings presents new opportunities for heating, ventilation, and air-conditioning products (HVAC). This paper presents a novel comfort solution that integrates a suspended radiant ceiling with diffuse ventilation, dubbed HVACeiling. In combination with the concrete slab, the HVACeiling has the potential to provide thermal comfort with minimal temperature offset, which supports operation of the heating and cooling system at temperatures very close to the room comfort temperature. The paper presents a parametric numerical study of the concept in a simplified two-pipe layout with fixed flow and fixed temperatures. First, the analysis was focused on different internal and solar loads, heat losses, and climatic locations with the aim of assessing the potential of self-regulation, i.e., no active controls, thermal comfort, ability to reduce peak loads and the consequential building design considerations. Secondly, the purpose was to analyse the concept in a generic office building with five offices and one meeting room and compare it to other HVAC solutions. The whole-year analyses of heating, cooling, energy performance, and thermal comfort were done using the building performance simulation software IDA ICE. It was found that it was possible to create thermal comfort in Paris, Munich, and Copenhagen with water circulating constantly with fixed temperatures of 20–24 °C without controls and with window sizes from 15 to 30% of the floor area. The studies showed that the HVACeiling reduced the operative peak temperatures on the warmest days in comparison with a standard radiant ceiling with mixing ventilation by 1 K. Compared to all-air solutions, the HVACeiling reduced the yearly energy consumption by 20–30% and the peak power in summer up to 69%. This study indicates that thermal comfort is achievable in a European context even at very small temperature offsets, which supports the use of more renewable energy sources.
Learning-Aided Optimal Power Flow Based Fast Total Transfer Capability Calculation
Authors: Liu Ji’ang , Liu Youbo , Qiu Gao , Shao Xiao
Published: February 2022

Total transfer capability (TTC) is a vital security indicator for power exchange among areas. It characterizes time-variants and transient stability dynamics, and thus is challenging to evaluate efficiently, which can jeopardize operational safety. A leaning-aided optimal power flow method is proposed to handle the above challenges. At the outset, deep learning (DL) is utilized to globally establish real-time transient stability estimators in parametric space, such that the dimensionality of dynamic simulators can be reduced. The computationally intensive transient stability constraints in TTC calculation and their sensitivities are therewith converted into fast forward and backward processes. The DL-aided constrained model is finally solved by nonlinear programming. The numerical results on the modified IEEE 39-bus system demonstrate that the proposed method outperforms several model-based methods in accuracy and efficiency.
Mitigating the Impact of an Official PEV Charger Deployment Plan on an Urban Grid
Authors: Konstantinidis George , Karapidakis Emmanuel , Paspatis Alexandros
Published: February 2022

Plug-in electric vehicles (PEVs) are rapidly increasing all over the world as electromobility is being promoted to reduce the greenhouse gas (GHG) emissions. PEVs locally produce zero emissions and they are more efficient in contrast to internal combustion engine vehicles. On the other hand, the impact of the uncoordinated charging of PEVs is expected to create new challenges for the established distribution grid. This article initially evaluates the impact of uncoordinated charging on the voltage regulation and transformer loading in the city of Heraklion, Greece. Then, a coordinated charging strategy is proposed to deal with the issue of transformer capacity violation by PEVs. Two cases were considered when the transformer overloading from PEV charging was taken into consideration: (a) keeping the transformer below its nominal capacity limit and (b) keeping the transformer below 90% of its nominal capacity limit. This was achieved by distributing the available capacity (nominal capacity minus the residential loads) of the transformer to the PEV chargers in a way that the aforementioned limits were satisfied. Real-world data of the distribution grid and the hourly power consumption of the city were used to validate the proposed method. Results show that possible transformer capacity violation can be tackled by the proposed coordinated charging, without exceeding the voltage regulation limits.
Implementation of the Improved Active Frequency Drift Anti-Islanding Method into the Three-Phase AC/DC Converter with the LCL Grid Filter
Authors: Dmitruk Krzysztof , Sikorski Andrzej
Published: February 2022

The article presents a modified standard Active Frequency Drift (AFD) method used to detect unintentional island operation in converters generating electricity from renewable energy sources to the power grid. The primary aim of each of the island operation detection methods is the possibility of shortening the energising of a separate part of the power grid. The proposed method eliminates fragments of the reference current signal when it reaches a constant value for a particular time. This part of the signal is replaced with the hyperbolic sine function. It allows reducing the value of Total Harmonic Distortions (THD) while maintaining the same effectiveness of island operation detection. The article contains a detailed description of the newly proposed type of disturbance generation. The proposed solution is verified by conducting simulation and laboratory tests. The possibility of shortening the island operation detection time is proven by increasing the maximum distortion introduced into the current without exceeding the permissible THD limit for converters connected to the power grid.
Spatial Network Structure of China’s Provincial-Scale Tourism Eco-Efficiency: A Social Network Analysis
Authors: Liu Qingfang , Song Jinping , Dai Teqi , Xu Jianhui , Li Jianmei , Wang Enru
Published: February 2022

While tourism eco-efficiency has been analyzed actively within tourism research, there is an extant dearth of research on the spatial network structure of provincial-scale tourism eco-efficiency. The Super-SBM was used to evaluate the tourism eco-efficiency of 30 provinces (excluding Tibet, Hong Kong, Macao and Taiwan). Then, social network analysis was employed to examine the evolution characteristics regarding the spatial network structure of tourism eco-efficiency. The main results are shown as follows. Firstly, tourism eco-efficiency of more than two thirds’ provinces witnessed an increasing trend. Secondly, the spatial network structure of tourism eco-efficiency was still loose and unstable during the sample period. Thirdly, there existed the multidimensional nested and fused spatial factions and condensed subsets in the spatial network structure of tourism eco-efficiency. However, there was still a lack of low-carbon tourism cooperation among second or third sub-groups. These conclusions can provide references for policymakers who expect to reduce carbon emissions from the tourism industry and to achieve sustainable tourism development.
Electricity Consumption and Economic Growth: Evidence from South Asian Countries
Authors: Majewski Sebastian , Mentel Urszula , Salahodjaev Raufhon , Cierpiał-Wolan Marek
Published: February 2022

The purpose of this study is to shed light on the nexus between electricity supply and economic growth in South Asian countries during 1990–2018. The study employs Pedroni’s panel cointegration test as well as Dumitrescu and Hurlin’s (DH) causality test for panel data. The empirical results confirm a long-term relationship between electricity supply and economic growth. We fail to reject the non-causal relationship between electricity supply and economic growth for the panel, thereby affirming the neutrality hypothesis. Single country causality analysis reveals the growth hypothesis in the case of Pakistan. These results have a number of policy implications. For example, governments can introduce measures to improve energy efficiency in Bangladesh, India and Sri Lanka without fear of harming economic growth. The results for Pakistan may also imply that fostering green energy generation would lead to a positive effect on economic growth via improved electricity production. The government may use various policy tools to stimulate adoption of renewable energy, such as fiscal incentives, low interest loans, or grants for rural populations to speed up the green energy transformation.
Assessment of the Possibility of Using Various Types of Renewable Energy Sources Installations in Single-Family Buildings as Part of Saving Final Energy Consumption in Polish Conditions
Authors: Wróblewski Piotr , Niekurzak Mariusz
Published: February 2022

The aim of this work is to develop a model of heat supply to buildings with almost zero energy consumption, indicating the significant importance of heat losses and gains in heating installations. The prepared model is to indicate the need for changes in the structure and topology of heating installations, resulting from the changing heat demand of buildings. The need to create a new model is heightened by changes that relate to tightening legal regulations related to energy consumption and demand, which must meet the standards of buildings in Poland from 2021. The article presents the assumptions and results of analyses of the use of energy installations in residential buildings that use renewable energy sources to balance energy consumption in various areas of its use. To achieve this goal, calculations were made using simulations of the impact of the use of installations using renewable energy sources on the energy performance of a building with different quality of partitions and improvement of energy efficiency in accordance with the Polish standard PN-EN 12831. The test results allow to choose the most advantageous, from the point of view of economic profitability, option of replacing installations in residential buildings, and they also allow to determine the possibilities of meeting national obligations in the field of final energy reduction and increasing the share of renewable energy sources in meeting its demand in accordance with the EU obligations imposed on Poland. Thermomodernization of buildings in the temperate climate zone allows for a reduction of 38% of energy demand over the entire life cycle of a building and a reduction of CO2 emissions by 99%.
Economic, Technological as Well as Environmental and Social Aspects of Local Use of Wood By-Products Generated in Sawmills for Energy Purposes
Authors: Mydlarz Katarzyna , Wieruszewski Marek
Published: February 2022

The article is the first in a series of works presenting the potential and possibilities of using for energy purposes wood waste and wood by-products generated at various stages of production in companies of the wood industry. The management of all wood waste and wood by-products is a pending issue due to the growing importance of the circular economy and broadly understood environmental protection. It is the environmental aspects and the climate targets defined by the EU that are the basis to determine the precise courses of action for the Member States and, as a result, also for companies. The article proves that regardless of the decisions taken by governments of individual countries in terms of broadly understood environmental protection, companies are free to implement pro-environmental solutions as part of their business activity. Due to the broad subject of the management of waste and by-products generated in different units of the wood industry, the possibilities of their use in terms of energy in primary wood processing companies–sawmills—are presented first. On the example of selected entities, the energy potential and possibilities of generating energy from renewable sources taking into account the principles of circular economy are presented. The possibilities of optimising production by improving redistribution of thermal energy, which may result in improving the economic efficiency of the assessed enterprises, were indicated.
Heat Transfer Analysis of a Co-Current Heat Exchanger with Two Rectangular Mini-Channels
Authors: Piasecka Magdalena , Hożejowska Sylwia , Pawińska Anna , Strąk Dariusz
Published: February 2022

This paper presents the results of research on heat transfer during fluid flow in a heat exchanger with two rectangular mini-channels. There was Fluorinert FC-72 flow, heated by the plate in the hot mini-channel, and co-current flow of distilled water in the cold mini-channel. Both fluids were separated by the copper plate. A thermal imaging camera was used to measure the temperature distribution of the outer surface of the heated plate. The purpose of the calculations was to determine the heat transfer coefficients at the contact surfaces: the heated plate—FC-72 and FC-72—the copper plate. Two mathematical models have been proposed to describe the heat flow. In the 1D approach, only the heat flow direction perpendicular to the fluid flow direction was assumed. In the 2D model, it was assumed that the temperature of the heated plate and FC-72 and the copper plate meet the appropriate energy equation, supplemented by the boundary conditions system. In this case, the Trefftz functions were used in numerical calculations. In the 1D model, the heat transfer coefficient at the interface between FC-72 and the copper plate was determined by theoretical correlations. The analysis of the results showed that the values and distributions of the heat transfer coefficient determined using both models were similar.
A Novel Analytical Approach for Optimal Integration of Renewable Energy Sources in Distribution Systems
Authors: Prakash Prem , Meena Duli Chand , Malik Hasmat , Alotaibi Majed A. , Khan Irfan Ahmad
Published: February 2022

The present research article focuses on an analytically based method for the optimal allocation and sizing of a renewable energy source (RES) capable of injecting both active and reactive powers in the distribution network. The placement of distributed generation (DG) in the distribution network reduces the magnitude of branch current in between the reference bus and the bus where DG is to be installed. Due to this, system power loss decreases significantly. The proposed method considers different levels of load in addition to peak load demand. The goal of the developed method is to minimize system losses by optimal DG allocations. In the proposed method, the optimum size of the DG is obtained on the basis of maximum loss saving criterion. For the execution of proposed method, only a base case load flow solution is required. The developed method has been tested on IEEE 69-bus and 33-bus radial distribution networks. On the basis of obtained results, it has been realized that the developed method is more capable of diminishing system energy losses.
Gamification as an Improvement Tool for HR Management in the Energy Industry—A Case Study of the Ukrainian Market
Authors: Polyanska Alla , Andriiovych Maksym , Generowicz Natalia , Kulczycka Joanna , Psyuk Vladyslav
Published: February 2022

Today, the energy sector requires special attention, and the widespread introduction of digital technologies, including gamification, allows key problems related to the energy policies of the European Union to be solved. The literature analysis presented here discusses the use of gamification among home energy production customers. However, there is a lack of analysis on the use of this tool in the management of energy sector companies. When considering the advantages of gamification elements in the training process, there was mention of this tool potentially being able to be used in HR management to realize the EU’s energy goals. The relevance of the topic has been explored in international studies that have shown that gamification increases employee productivity and motivation. In the article, the directions of gamification in the practices of Ukrainian organizations are investigated. The main principles of effective gamification implementation in HR management, at energy enterprises in particular, are highlighted. A survey on gamification perception by Ukrainians from educational and related areas has been organized and analyzed. The survey results are supplemented by the results of the digitalization state analysis conducted for energy companies, which represent an important foundation for the implementation of gamification into practice. The prototype of a simulation model in which a solar panel must be connected to a controller is worked out as an example of the element usage incurred by gamification in the learning and training process, both in enterprise and in university activity. The present research underlines the importance of an interdisciplinary approach in gamification utilization, as it allows the skill-gaining processes in managerial and technical fields to be combined. The main advantages of gamification in HR management in enterprises are described by impact categories, such as staff appraisal, motivation, and corporate culture and internal communications. The use of gamification in companies in the energy sector is expected to contribute to the support of energy policy, as well as to the efficient integration of Ukrainian energy companies into the EU energy market.
Rice Straw: A Waste with a Remarkable Green Energy Potential
Authors: Bressan Maurizio , Campagnoli Elena , Ferro Carlo Giovanni , Giaretto Valter
Published: February 2022

With reference to the province of Novara in northwest Italy, this study aims to raise awareness about the environmental benefits that can derive from the use of alternative rice straw management practices to those currently in use, also highlighting how the use of these straws for energy purposes can be a valid alternative to the use of non-renewable resources. Using the LCA (Life Cycle Assessment) method, the two rice straw management practices currently in place (open field combustion and straw incorporation) were compared with an alternative strategy consisting in their collection and removal. The results show that removal of straw allows reducing the emissions of pollutants significantly: about one-hundredth of the PM (Particulate Matter) formation compared to the open-field burning and about one-tenth of the ozone depletion (CFCs, HCFCs, halons, etc.) compared to both the other two practices. Moreover, the LCA results show how the use of rice straw to produce energy as an alternative to conventional fuels helps to reduce the global warming potential of rice cultivation.
Phenotypic Comparison of Three Populations of Juniperus turbinata Guss. in North-Eastern Morocco
Authors: Sahib Nargis , Boumediene Mehdi , Abid Malika , Mihamou Aatika , Serghini-Caid Hana , Elamrani Ahmed , Hano Christophe , Addi Mohamed
Published: February 2022

Juniperus turbinata Guss. is a native species of Morocco; however, an exhaustive taxonomic description based on phenotypical characterization of north-eastern Moroccan population species is lacking, which might lead to taxonomic confusion. In order to expound the phenotypic description of J. turbinata of the north-eastern Moroccan population and to examine the taxonomic differences within it; a comparative analysis of cones, leaves, and seeds was performed between three populations. A total of 280 samples were compared on the basis of nine measured and eight calculated traits. The results reveal significant interpopulation changes in the studied characteristics of cones, leaves, and seeds. The most discriminating traits were associated with the proportion between cone diameter and number of seeds. We detected the lowest number of seeds in coastal population when compared to other localities, but at the same time, the seeds from the littoral were the longest and the widest. In addition, the semi-continental population had the highest quantity of seeds, and leaves had intermediate values for the majority of the assessed traits. The phenotypical difference between populations demonstrates a certain adaptability of the species in a biogeographical pattern. This study is a contribution to completing the description of patterns of phenotypical differences of the Phoenician juniper in the Mediterranean region, and confirms its evolutionary plasticity linked to adaptation to local environmental conditions.
Effects of Medium Supplements on Somatic Embryo Maturation and DNA Methylation in Pseudotsuga gaussenii Flous, a Species under Protection
Authors: Gao Ying , Chen Xiaoyi , Cui Ying , Zhao Huanhuan , Zhao Ruirui , Liu Chengbi , Zhao Jian , Zhang Jinfeng , Kong Lisheng
Published: February 2022

Pseudotsuga gaussenii is a forest species under protection in China. Propagation via somatic embryogenesis is efficient and needed for recovering this species. In this research, effects of medium supplements, i.e., methylglyoxal-bis (guanylhydrazone) (MGBG), polyethylene glycol (PEG), and maltose, on somatic embryo (SE) development were studied. More mature SEs developed with the pre-maturation treatment medium supplemented with 50 μM or 100 μM MGBG. During SE maturation, when the medium was supplemented with both PEG and maltose, the over-proliferation of embryogenic tissue was suppressed. When maltose was eliminated from the maturation medium, SEs were slightly smaller but developed better than other treatments due to the supply of lower carbon source, whereas when PEG was taken out from the maturation medium, no mature SE was obtained, only the heavily-proliferated plant tissue. Meanwhile, DNA methylation levels differed in these SE maturation cultures at the late culture stage of SE maturation. The level increased sharply with no maltose treatment (20.28%) while decreasing without PEG supplement (10.35%). DNA methyltransferase genes MET1-1, MET1-2, MET1-3, CMT3, DRM1, and DRM2 were partially cloned in this study to detect their expression level via qPCR. Expression of these genes, except MET1-3, in the culture of no PEG was higher significantly than the cultures of other treatments at weeks 1, 3, and 10. Our results suggested that MGBG and/or PEG play an important role in stimulating SE development and maturation. Furthermore, sugar supplements at a lower level benefited SE maturation in Pseudotsuga gaussenii.
Using Analytic Hierarchy Process and Best–Worst Method in Group Evaluation of Urban Park Quality
Authors: Srdjevic Bojan , Srdjevic Zorica , Reynolds Keith M. , Lakicevic Milena , Zdero Senka
Published: February 2022

The paper compares two multi-criteria methods, the analytic hierarchy process (AHP) and the best–worst method (BWM), in assessing criteria related to the quality of urban parks. The criteria assessed were accessibility, location, biodiversity preservation, park equipment, water elements, terrain configuration, cultural and historical value, and the presence of small architectural objects. Five decision-makers participated in the research, having expertise in urban greenery, urban forestry, environmental protection, landscape design, and cultural and historical heritage. The results of decision-makers’ evaluations were compared at individual and group levels after the application of three aggregation procedures: CRITIC, ENTROPY, and WGGM (weighted geometric mean method). Similarities in results, i.e., priorities of analyzed criteria after applying the two different decision support methods, indicated high consistency between experts during the cognitive evaluation processes. All applied aggregation schemes performed well and may be considered trustworthy in identifying the group solution. One of the conclusions is that either the AHP or the BWM can be efficiently used in evaluations of criteria for assessing the quality of urban parks if the members of a group are consistent, regardless of whether the consensus process is properly carried out before the decision-making process.
A Novel Environment-Friendly Adhesive Based on Recycling of Broussonetia papyrifera Leaf Forestry Waste Protein
Authors: Li Cheng , Tang Yang , Wang Yujie , Yuan Xiaoyu , Zhang Bengang , Wu Zhigang , Tian Huafeng
Published: February 2022

Wood adhesive was prepared using Broussonetia papyrifera waste leaf protein as the raw material. The performance of the B. papyrifera leaf protein adhesive compared to soy protein was investigated using X-ray diffraction, Fourier transform infrared spectroscopy, and differential scanning calorimetry. The results indicated that both B. papyrifera leaf protein and soy protein were spherical proteins that could easily form three-dimensional crosslinked network structures and were of potential for protein adhesive preparation. The B. papyrifera leaf and soy protein-based adhesives had similar curing behaviors, but the crosslinking reaction of B. papyrifera leaf protein-based adhesive seems to be more complex than that of the soy protein-based adhesive. The B. papyrifera leaf protein-based adhesive had a lower increasing trend of particle size and crystallinity than the soy-based protein adhesive, and its water resistance and bonding strength were also weaker. The plywood with BP leaf protein adhesive had dry and wet shear strengths of 0.93 MPa and 0.59 MPa, respectively. These results are promising for future industrial production using Broussonetia papyrifera waste leaf protein as a new protein wood adhesive in the wood industry.
Comparison of Juvenile, Drought Tolerant Black Locust (Robinia pseudoacacia L.) Clones with Regard to Plant Physiology and Growth Characteristics in Eastern Hungary: Early Evaluation
Authors: Ábri Tamás , Keserű Zsolt , Borovics Attila , Rédei Károly , Csajbók József
Published: February 2022

(1) Background: The aim of our study is to present the results of initial growth and plant physiology studies of newly selected, vegetative propagated black locust clones, with a view to assess their suitability for the establishment of fast growing tree plantations for the production of high quality timber in marginal (semi-arid) sites. (2) Methods: In the spring (May) and autumn (November) of 2021, full inventories were carried out in the black locust industrial tree plantation. The Normalized Difference Vegetation Index (NDVI) values were observed monthly from May to September 2021. For measuring the assimilation parameters the net assimilation, transpiration, stomatal conductance, intercellular CO2 concentration, and other physiological parameters were recorded. (3) Results: Robinia pseudoacacia ‘NK2’ clone showed the highest assimilation rate and it produced the most height increment in the growing season, from May 2021 to November 2021. The discriminant analysis classified successfully the black locust clones, 86.7% of original grouped cases were correctly classified. (4) Conclusions: The study of industrial tree plantations is of great practical importance. As black locust can tolerate even marginal site conditions, the lack of timber can be reduced in the future by establishing black locust industrial tree plantations. To be able to produce good quality industrial wood on the plantations, it is essential to study the phytophysiological properties of the trees (biomass production, vegetation activity of plants, chlorophyll content, photosynthetic activity) in addition to the traditional stand full inventories.
Effect of Sodium Hydroxide, Succinic Acid and Their Combination on Densified Wood Properties
Authors: Augustina Sarah , Wahyudi Imam , Dwianto Wahyu , Darmawan Teguh
Published: February 2022

The effect of NaOH, succinic acid and their combination used as pretreatments on selected properties of densified wood samples of pisang putih (Mezzettia spp.), nyatoh (Palaquium spp.) and sepetir (Sindora spp.) has been studied. The properties of these samples were then compared with those of untreated wood (control) and densified wood samples without any pretreatment (HD wood). For alkali-pretreatment, after immersion in 10% NaOH (w/w) for 1, 2 and 3 h, the samples were immediately compressed; for acid-pretreatment, the sample was impregnated with 10% succinic acid (w/w) using a vacuum of −50 kPa for 30 min and a pressure of 7 bar for 2 h before pressing; while for the combination-pretreatment, the sample was initially immersed in 10% NaOH then impregnated with 10% succinic acid (w/w) and finally densified/compressed. Compression was applied in a radial direction and carried out in an open system using a hot press machine at 180 °C and 7 MPa specific pressure for 30 min with a 40% compression ratio. The results showed that densified wood with or without pretreatment had a higher specific gravity (SG) than the control, whereas sepetir wood showed the greatest increase in SG. The alkali- and combination-pretreatments resulted in a higher C-set value than in the control, HD and acid-pretreated samples. Acid-pretreatment resulted in the best improvement in dimensional stability compared to the other pretreatments. Increasing the immersion time in NaOH solution was proven to be able to increase dimensional stability both in alkali- and combination-pretreatments, although water absorption values varied.
Attitudes towards Foresters in Polish Society
Authors: Krokowska-Paluszak Małgorzata , Wierzbicka Anna , Łukowski Adrian , Gruchała Arkadiusz , Sagan Jacek , Skorupski Maciej
Published: February 2022

In recent years, foresters in Poland have faced a decreasing level of social acceptance. Scientists have demonstrated that core values and personal experience shape the social acceptance of foresters and their work. The aim of our study was to determine what kind of attitudes towards foresters (ATF) do Poles have? What shapes Poles’ ATF? Is recreational behavior connected to the ATF? Which foresters’ PR and educational activities have the biggest impact on peoples’ ATF? The research tool used was the original research questionnaire consisting of closed questions only. A sample of 1000 Poles was selected in 2018. Most respondents (85%) held an ATF that was at least slightly positive. Most of the respondents recognized that the foresters are well prepared to do their job, and considered that the foresters perform their job well. Socio-demographic characteristics had no effect on ATF. Personal experiences, such as frequent visits to the forest; the use of educational, bicycle, jogging or horse riding paths in the forest; the picking of forest berries and mushrooms; and knowing a forester, have a small impact on the attitude. An organized community offer provided by foresters, such as picnics, and family events, etc., had no statistical effect on the attitude score.
Impact of Ice-Storms and Subsequent Salvage Logging on the Productivity of Cunninghamia lanceolata (Chinese Fir) Forests
Authors: Zhu Yu , Liu Shuguang , Yan Wende , Deng Deming , Zhou Guangyi , Zhao Meifang , Gao Fei , Zhu Liangjun , Wang Zhao , Xie Menglu
Published: February 2022

The impacts of ice-storms on forests have received growing attention in recent years. Although there is a wide agreement that ice-storms significantly affect forest structure and functions, how frequent ice-storms and subsequent salvage logging impact productivity of subtropical coniferous forests in the future still remains poorly understood. In this study, we used the Ecosystem Demography model, Version 2.2 (ED-2.2), to project the impact of salvage logging of ice-storm-damaged trees on the productivity of Cunninghamia lanceolata-dominated coniferous forest and C. lanceolata-dominated mixed coniferous and broadleaved forests. The results show that forest productivity recovery is delayed in coniferous forests when there is no shade-tolerant broadleaved species invasion after ice-storms, and C. lanceolata could continue to dominate the canopy in the mixed coniferous and broadleaved forests under high-frequency ice-storms and subsequent salvage logging. The resistance and resilience of the mixed coniferous and broadleaved forests to high-frequency ice-storms and subsequent salvage logging were stronger compared to coniferous forests. Although conifers could continue to dominate the canopy under shade-tolerant broadleaved species invasion, we could not rule out the possibility of a future forest community dominated by shade-tolerant broadleaf trees because there were few coniferous saplings and shade-tolerant broadleaf species dominated the understory. Our results highlight that post-disaster forest management should be continued after high-frequency ice-storms and subsequent salvage logging in C. lanceolata forests to prevent possible shade-tolerant, late successional broadleaf trees from dominating the canopy in the future.
The Impact of Sanding and Thermal Compression of Wood, Varnish Type and Artificial Aging in Indoor Conditions on the Varnished Surface Color
Authors: Bekhta Pavlo , Krystofiak Tomasz , Lis Barbara , Bekhta Nataliya
Published: February 2022

The aim of this pioneering study was to compare and evaluate two different pre-treatment processes of wooden surfaces prior to varnishing by sanding or thermal compression in terms of the impact on the color characteristics of the varnished surface. In the experiment, a wood veneer of black alder and birch before varnishing was subjected to sanding with a sandpaper of 180 grit size, or thermal compression at temperatures of 180 and 210 °C. Three different kinds of commercially manufactured transparent varnish (water-based (WB) varnish, polyurethane (PUR) varnish and UV-cured (UV) varnish) were applied to the prepared veneer surfaces. The samples prepared in this way were also subjected to an artificial aging process in indoor conditions by ultraviolet light and infrared irradiation (UVL + IR). The colors of the surfaces in the CIE L*a*b* system were measured and color differences (ΔL*, Δa*, Δb* and ΔE) were determined for sanded and thermally densified, unvarnished and varnished, as well as subjected to accelerated aging surfaces. It was found that thermally densified surface-varnished veneer is more resistant to color changes during artificial aging compared to when sanded and surface-varnished. The transparent varnish systems showed better photo-stability, when thermally densified wood veneer was used as substrate than that of sanded wood. The WB varnish showed the greatest resistance to discoloration during UVL + IR irradiation, followed by PUR and UV. The preliminary findings obtained in this study indicated that replacing the sanding process with thermal compression of wood surface before varnishing could be considered as an alternative method of producing varnished panels with satisfactory color properties of surface.
Effect of Aspect-Slope on the Growth of Conifers in a Harsh Boreal Climate of Northwest Sweden
Authors: Ogana Friday N. , Sjödin Fredrik , Holmström Emma , Fries Clas , Nilsson Urban
Published: February 2022

Tree development is affected by different factors including topographic features. The effect could be even more complex in harsh environments such as in the northwest of Sweden. In this study, we analyzed the effect of aspect-slope on the development up to the age of 34 years of five species: black spruce, lodgepole pine, Norway spruce, Siberian larch and Scots pine. The species were planted in a field experiment on the southwest slope, mountaintop, and northeast slope in a randomized complete block design in the northwest of Sweden (latitude 67°) with 2 m × 2 m spacing. No re-measurement data were available and, as such, retrospective diameters and heights were derived from sample discs and measurement of length to every branch whorl, respectively. Variations in tree survival rate, height and diameter were analyzed using a linear mixed-effect model. The results showed that there were significant (p < 0.05) differences between species in survival rate, diameter and height growth; in some cases, differences were found between contrasting aspect-slope. Black spruce and Siberian larch had the best survival rate under this harsh boreal climate. However, Siberian larch had the best growth and developed well on the mountaintop and northeast slope. Lodgepole pine developed well on the southwest slope. Scots pine also grew well on the southwest slope and mountaintop. Norway spruce had the slowest growth. Based on this study, Siberian larch and lodgepole pine can serve as alternatives to the two traditional conifer species, Norway spruce and Scots pine, used in Sweden. Siberian larch is particularly suitable because it is able to withstand the harshness of the boreal environment.
Steep Slope Harvest System Models for Small to Large Trees
Authors: West Todd , Sessions John , Strimbu Bogdan M.
Published: February 2022

Background: Tethered cut-to-length and cable yarding systems with tethered falling equipment are increasingly used to harvest trees from slopes exceeding 30–60% more safely and at reduced financial cost than less mechanized harvest systems. Existing studies of harvest equipment typically isolate one or two pieces of equipment in a harvest system and often occur on sites with slopes below 50% and trees less than 60 cm in diameter. Methods: We analyzed machine capabilities and productivity regressions to extrapolate existing models to steep slope harvesting of trees up to 115 cm diameter. The resulting individual machine models are integrated into models of cut-to-length and long-log harvest system productivity. We estimated the financial operating costs of the harvest systems considered from equipment pricing and operator wages. Results: Analysis of even-age Douglas-fir (Pseudotsuga menziesii) and western hemlock (Tsuga heterophylla) rotations suggests eight-wheel forwarder productivity, swing yarder productivity, and mechanization of manual chainsaw labor with tethered harvesters as primary controls on harvest costs. Conclusions: The proposed model enables predictions across a greater range of slopes and tree sizes than those previously modeled, creating a foundation for future research into the cost and productivity of steep slope harvesting systems.
Securing IoT Devices against Differential-Linear (DL) Attack Used on Serpent Algorithm
Authors: Muthavhine Khumbelo , Sumbwanyambe Mbuyu
Published: February 2022

Cryptographic algorithms installed on Internet of Things (IoT) devices suffer many attacks. Some of these attacks include the differential linear attack (DL). The DL attack depends on the computation of the probability of differential-linear characteristics, which yields a Differential-Linear Connectivity Table (DLCT). The DLCT is a probability table that provides an attacker many possibilities of guessing the cryptographic keys of any algorithm such as Serpent. In essence, the attacker firstly constructs a DLCT by using building blocks such as Substitution Boxes (S-Boxes) found in many algorithms’ architectures. In depth, this study focuses on securing IoT devices against DL attacks used on Serpent algorithms by using three magic numbers mapped on a newly developed mathematical function called Blocker, which will be added on Serpent’s infrastructure before being installed in IoT devices. The new S-Boxes with 32-bit output were generated to replace the original Serpent’s S-Boxes with 4-bit output. The new S-Boxes were also inserted in Serpent’s architecture. This novel approach of using magic numbers and the Blocker Function worked successfully in this study. The results demonstrated an algorithm for which its S-Box is composed of a 4-bit-output that is more vulnerable to being attacked than an algorithm in which its S-Box comprises 32-bit outputs. The novel approach of using a Blocker, developed by three magic numbers and 32-bits output S-Boxes, successfully blocked the construction of DLCT and DL attacks. This approach managed to secure the Serpent algorithm installed on IoT devices against DL attacks.
Parcel-Level Risk Affects Wildfire Outcomes: Insights from Pre-Fire Rapid Assessment Data for Homes Destroyed in 2020 East Troublesome Fire
Authors: Meldrum James R. , Barth Christopher M. , Goolsby Julia B. , Olson Schelly K. , Gosey Adam C. , White James (Brad) , Brenkert-Smith Hannah , Champ Patricia A. , Gomez Jamie
Published: February 2022

Parcel-level risk (PLR) describes how wildfire risk varies from home to home based on characteristics that relate to likely fire behavior, the susceptibility of homes to fire, and the ability of firefighters to safely access properties. Here, we describe the WiRē Rapid Assessment (RA), a parcel-level rapid wildfire risk assessment tool designed to evaluate PLR with a small set of measures for all homes in a community. We investigate the relationship between 2019 WiRē RA data collected in the Columbine Lake community in Grand County, Colorado, and whether assessed homes were destroyed in the 2020 East Troublesome Fire. We find that the overall parcel-level risk scores, as well as many individual attributes, relate to the chance that a home was destroyed. We also find strong evidence of risk spillovers across neighboring properties. The results demonstrate that even coarsely measured RA data capture meaningful differences in wildfire risk across a community. The findings also demonstrate the importance of accounting for multiple aspects of PLR, including both hazards and susceptibility, when assessing the risk of wildfire to homes and communities. Finally, the results underscore that relatively small actions by residents before a fire can influence wildfire outcomes.
Effect of Large-Scale Paddy Rice Drying Process Using Hot Air Combined with Radio Frequency Heating on Milling and Cooking Qualities of Milled Rice
Authors: Chitsuthipakorn Karn , Thanapornpoonpong Sa-nguansak
Published: February 2022

The objectives of the study on a continuous flow hot air dryer combined with radio frequency heating at different temperatures (HA/RF) (38 °C, 42 °C, 46 °C, and 50 °C) in a large-scale process compared with conventional continuous flow hot air drying (HA) were (1) to investigate the drying characteristics, drying kinetics, and milling quality of the process and (2) to observe the cooking quality and compare the sensory differences of the cooked rice after treatment. The drying characteristics and moisture diffusivity showed that the higher the radio frequency (RF) heating temperature, the shorter the drying time. The specific energy consumption and energy cost decreased when the RF heating temperature increased. The optimal condition in terms of fissure percentage was HA/RF42. In addition, there were no significant differences in head rice yield and white rice color determination, amylose content, texture profiles, and pasting properties in all HA/RF treatments. In the triangle test, it was found that at least 6% of the population could perceive a difference between HA and HA/RF50. In conclusion, this study proposes the further development of the HA/RF drying process at low-temperature profiles and shows the great potential of RF technology for commercial drying in rice industry.