bluuebunny/crossref_metadata_2025 huggingface dataset:
Heat Dissipation in Variable Underground Power Cable Beddings: Experiences from a Real Scale Field Experiment
Authors: Verschaffel-Drefke Christoph , Schedel Markus , Balzer Constantin , Hinrichsen Volker , Sass Ingo
Published: November 2021

To prevent accelerated thermal aging or insulation faults in cable systems due to overheating, the current carrying capacity is usually limited by specific conductor temperatures. As the heat produced during the operation of underground cables has to be dissipated to the environment, the actual current carrying capacity of a power cable system is primarily dependent on the thermal properties of the surrounding porous bedding material and soil. To investigate the heat dissipation processes around buried power cables of real scale and with realistic electric loading, a field experiment consisting of a main field with various cable configurations, laid in four different bedding materials, and a side field with additional cable trenches for thermally enhanced bedding materials and protection pipe systems was planned and constructed. The experimental results present the strong influences of the different bedding materials on the maximum cable ampacity. Alongside the importance of the basic thermal properties, the influence of the bedding’s hydraulic properties, especially on the drying and rewetting effects, were observed. Furthermore, an increase in ampacity between 25% and 35% was determined for a cable system in a duct filled with an artificial grouting material compared to a common air-filled ducted system.
Nonlinear Identification with Constraints in Frequency Domain of Electric Direct Drive with Multi-Resonant Mechanical Part
Authors: Łuczak Dominik
Published: November 2021

Knowledge of a direct-drive model with a complex mechanical part is important in the synthesis of control algorithms and in the predictive maintenance of digital twins. The identification of two-mass drive systems with one low mechanical resonance frequency is often described in the literature. This paper presents an identification workflow of a multi-resonant mechanical part in direct drive with up to three high-frequency mechanical resonances. In many methods, the identification of a discrete time (DT) model is applied, and its results are transformed into a continuous-time (CT) representation. The transformation from a DT model to a CT model has limitations due to nonlinear mapping of discrete to continuous frequencies. This problem may be overcome by identification of CT models in the frequency domain. This requires usage of a discrete Fourier transform to obtain frequency response data as complex numbers. The main work presented in this paper is the appropriate fitting of a CT model of a direct-drive mechanical part to complex number datasets. Fitting to frequency response data is problematic due to the attraction of unexcited high frequency ranges, which lead to wrong identification results of multi-mass (high order) drive systems. Firstly, a CT fitting problem is a nonlinear optimization problem, and, secondly, complex numbers may be presented in several representations, which leads to changes in the formulation of the optimization problem. In this paper, several complex number representations are discussed, and their influence on the optimization process by simulation evaluation is presented. One of the best representations is then evaluated using a laboratory setup of direct drive with unknown parameters of three high mechanical resonance frequencies. The mechanical part of the examined direct drive is described by three mechanical resonances and antiresonances, which are characteristic of a four-mass drive system. The main finding is the addition of frequency boundaries in the identification procedure, which are the same as those in the frequency range of the excitation signal. Neither a linear least-square algorithm nor a nonlinear least-square algorithm is suitable for this approach. The usage of nonlinear least-square algorithm with constraints as a fitting algorithm allows one to solve the issue of modeling multi-mass direct-drive systems in the frequency domain. The second finding of this paper is a comparison of different cost functions evaluated to choose the best complex number representation for the identification of multi-mass direct-drive systems.
What Are the Policy Impacts on Renewable Jet Fuel in Sweden?
Authors: Trinh Jenny , Harahap Fumi , Fagerström Anton , Hansson Julia
Published: November 2021

The aviation industry contributes to more than 2% of global human-induced CO2-emissions, and it is expected to increase to 3% by 2050 as demand for aviation grows. As the industry is still dependent on conventional jet fuel, an essential component for a carbon-neutral growth is low-carbon, sustainable aviation fuels, for example alternative drop-in fuels with biobased components. An optimization model was developed for the case of Sweden to examine the impacts of carbon price, blending mandates and penalty fee (for not reaching the blending mandate) on the production of renewable jet fuel (RJF). The model included biomass gasification-based Fischer–Tropsch (FT) jet fuel, Power-to-Liquid (PTL) jet fuel through the FT route and Hydrothermal liquefaction (HTL)-based jet fuel. Thus, this study aims at answering how combining different policies for the aviation sector can support the production of RJF in Sweden while reducing greenhouse gas (GHG) emissions. The results demonstrate the importance of implementing policy instruments to promote the production of RJF in Sweden. The blending mandate is an effective policy to both promote RJF production while reducing emissions. The current level of the penalty fee is not sufficient to support the fuel switch to RJF. A higher blending mandate and carbon price will accelerate the transition towards renewable and sustainable fuels for the aviation industry.
Business Model Canvas and Energy Enterprises
Authors: Dobrowolski Zbysław , Sułkowski Łukasz
Published: November 2021

So far, little is known about the Business Model Canvas development in the energy sector. In this paper, we fill this knowledge gap and modify the Business Model Canvas. Based on the cause–effect analysis combined with the literature searching method, we suggest that Osterwalder’s Canvas for energy enterprise should be modified because the available Canvas adaptations cannot fully capture the energy enterprise’s business model or realise its business operations combined with the public interest. We propose a new original Canvas adaptation by adding two crucial blocks representing the mission, energy accountability, and impact on stakeholders in the Business Model Canvas. The findings make two main contributions. First, they contribute to developing entrepreneurship theory. We formulate an original definition of a business model, first showing the limitations of current definitions. We verify Chesbrough’s functions of business models. Second, compared to earlier business model frameworks, the new model clearly points out that accountability in firms’ everyday businesses is at the core of business development. Moreover, this article formulates future research avenues in the energy sector and provides a helpful planning tool for practitioners.
Integrating Photovoltaic (PV) Solar Cells and Supercapacitors for Sustainable Energy Devices: A Review
Authors: Nordin Noor Afeefah , Mohamed Ansari Mohamed Nainar Mohamed , M. Nomanbhay Saifuddin M. , A. Hamid Nasri A. , Tan Nadia M. L. , Yahya Zainudin , Abdullah Izhan
Published: November 2021

Hybrid systems have gained significant attention among researchers and scientists worldwide due to their ability to integrate solar cells and supercapacitors. Subsequently, this has led to rising demands for green energy, miniaturization and mini-electronic wearable devices. These hybrid devices will lead to sustainable energy becoming viable and fossil-fuel-based sources of energy gradually being replaced. A solar photovoltaic (SPV) system is an electronic device that mainly functions to convert photon energy to electrical energy using a solar power source. It has been widely used in developed countries given that they have advanced photovoltaic (PV) technology that reduces dependence on fossil fuels for energy generation. Furthermore, a supercapacitor is an alternative solution for replacing heavy batteries and it is a system with a prominent high power density and a long life cycle. Its unique properties of high capacitance with low voltage limits lead to this highly in-demand material being incorporated into goods and services that are produced by the electrical and electronics industries. It is another option for grid-based power or large batteries. Since supercapacitors have the ability to store huge amounts of energy, they allow for a novel system that integrates supercapacitors with solar cells in which energy generation and energy storage are combined into one system. This paper explores the common materials that are used for solar cells and supercapacitors, the working mechanisms, the effectiveness of the integrated device and the technical challenges that are encountered when refining this device. Hence, this review serves as a guide for choosing the right materials and methods in order to produce an integrated PV solar cell–energy storage device for various applications.
On the Power Lines—Electromagnetic Shielding Using Magnetic Steel Laminates
Authors: Damatopoulou Tatiana , Angelopoulos Spyros , Christodoulou Christos , Gonos Ioannis , Hristoforou Evangelos , Kladas Antonios
Published: November 2021

Protection against the electromagnetic fields around high-voltage transmission lines is an issue of great importance, especially in the case of buildings near power lines. Indeed, the developed fields can be harmful for the habitants and electrical/electronic devices, so the implementation of appropriate measures to address the above electromagnetic interference issue is necessary in order to ensure the safety of both human beings and equipment. Several practices have been proposed to reduce the electric and the magnetic fields around overhead and underground transmission lines (minimum distance, shielded cables, anechoic chamber etc.). In this context, the scope of the current paper is the use of highly permeable magnetic sheets for shielding purposes, along with the development of an appropriate procedure, based on finite element analysis (FEA) for the efficient design of passive shielding. The simulation results are compared with laboratory measurements in order to confirm the adequacy of the proposed methodology. The good agreement between the FEA outcomes and the experimental results confirms that the developed FEA tool can be trustfully used for the design of the shielding means in the case of overhead or underground power lines.
Solid Digestate—Physicochemical and Thermal Study
Authors: Dziedzic Krzysztof , Łapczyńska-Kordon Bogusława , Jurczyk Michał , Arczewska Marta , Wróbel Marek , Jewiarz Marcin , Mudryk Krzysztof , Pająk Tadeusz
Published: November 2021

Biogas production is an important component of sustainable energy management. In addition to energy-rich biogas, this process also generates solid waste in the form of digestate. The management of this stream has been problematic for many years. One promising method of utilizing this fraction seems to be incineration under controlled conditions. This paper presents an analysis of mixtures of different digestates to assess their suitability for incineration. Four digestates based on corn silage CS and apple pomace AP were used as test fuel. The ultimate and proximate analysis showed that this fuel deviates from the standards accepted for pure biomass, but was found in other fuels, especially those treated as waste. This materials can be a valuable source of energy, but combustion needs be undertaken in special units. Moisture content of investigated digestate-type ranges from 11.9–12.2% and ash content ranges from 8.2% to 11.6%. This could lead to ash sintering and slugging problems, which are problematic, especially because it is not designed for such types of fuel boilers. The study showed correlations between the elemental composition and the course of basic combustion processes. The ultimate analysis of all mixtures shows that the shares of major elements looks similar. These results are connected with the thermogravimetric analysis TGA, which shows similar thermal decomposition for all four mixtures. It is valuable information because, in this special case, when we have mixtures of corn silage and apple pomace originated digestates, the changes in the ratio CS:AP will not affect combustion significantly.
Multi-Attribute Rating Method for Selecting a Clean Coal Energy Generation Technology
Authors: Lipka Wioletta , Szwed Cezary
Published: November 2021

The process of technology management contains various stages, such as the identification, selection, acquisition, implementation, and maintenance of technologies. In the case of power generation companies, a key aspect of the selection stage is the choice of generation technologies for newly commissioned units. The investment decision depends on many factors, primarily economic, environmental, social, technological, and legal, and represents a complex multi-criteria problem. Currently, the decision is further complicated by the often unpredictable tightening of environmental standards, forcing the closure of conventional sources, on which many countries have so far based their energy security. The paper analyzes the problem of choosing one of the so-called clean coal technologies to be implemented in conditions of transformation of the power sector. In this paper, five selected clean coal technologies are characterized, and the SMART method is adopted to technology selection. The following technologies were considered: supercritical coal-fired power plant (with and without CCS), IGCC power plant (with and without CCS), and IGCC power plant with CCS and integrated hydrogen production. Nine practical criteria (in three main groups: environmental, technological, economic) for comparing technologies are defined, computational experiments performed, and conclusions from the research presented. The work was based on the literature study of multi-criteria decision support and an analysis of power sector needs based on the example of the Polish power sector. The conducted research, apart from the technology recommendation, led to the conclusion that the chosen method may be applied to decision-making in the field of power generation technology management. The study also indicated the potential direction of the development of a power generation structure in a situation where a component of ensuring energy security is the use of available coal fuels.
Experimental and Kinetic Studies on Steam Gasification of a Biomass Char
Authors: Zhao Shengguo , Ding Liang , Ruan Yun , Bai Bin , Qiu Zegang , Li Zhiqin
Published: November 2021

The maximum gasification rate of corn stalk char (CSC) appeared at high conversion range, and its quite different gasification behaviors from other carbonaceous materials are all derived from the catalytic effect of alkali and alkali earth metals (AAEMs), so it is necessary to study the effect of AAEMs and gasification kinetics of such biomass char. However, there are few systematic discussions about this effect and kinetic modeling. Thus, in this study, CSC samples were prepared in a fast pyrolysis fixed-bed reactor, and its gasification experiments were conducted on a pressurized magnetic suspension balance at various total pressures (0.1–0.7 MPa), steam concentrations (10–70 vol.%) and temperatures (725–900 °C). Moreover, a water-leached CSC (H2O-CSC) was also prepared to evaluate the impact of AAEMs on the gasification performance of CSC, and some well-known models were adopted to describe the gasification behaviors. On the basis of these results, the effect of primary AAEMs on the gasification behaviors of CSC and gasification kinetic modeling were obtained. Results showed total pressure had no obvious influence on the gasification rate of CSC, and the reaction order varied at 0.43–0.55 with respect to steam partial pressures. In addition, the modified random pore model (MRPM) and Langmuir–Hinshelwood (L-H) model were satisfactorily applied to predict the gasification behaviors of CSC. The catalytic effect of AAEMs on CSC gasification was weakened due to water-leaching treatment. A random pore model (RPM) could describe the gasification behavior of H2O-CSC well, followed by grain model (GM) and volumetric model (VM).
The Impact of Aging-Preventive Algorithms on BESS Sizing under AGC Performance Standards
Authors: Morales Cristobal , Lismayes Augusto , Chavez Hector , Chamorro Harold R. , Reyes-Chamorro Lorenzo
Published: November 2021

It is normally accepted that Battery Energy Storage Systems improve frequency regulation by providing fast response to the Automatic Generation Control. However, currently available control strategies may lead to early Energy Storage Systems aging given that Automatic Generation Control requirements are increasing due to zero carbon power generation integration. In this sense, it is important to analyze the aging phenomena in order to assess the technical–economical usefulness of Battery Energy Storage Systems towards zero carbon power systems. In order to avoid early aging, various proposals on aging-reducing algorithms can be found; however, it is unclear if those aging-reducing algorithms affect the performance of Battery Energy Storage Systems. It is also unclear whether those effects must be internalized to properly dimension the capacity of Battery Energy Storage Systems to both comply with performance standards and to prevent early aging. Thus, this paper estimates the storage capacity of a Battery Energy Storage Systems to comply with Automatic Generation Control performance standard under aging-reducing operating algorithms by dynamics simulations of a reduced-order, empirically-validated model of the Electric Reliability Council of Texas. The results show the relationship between the required performance of Automatic Generation Control and Battery Energy Storage System capacity, considering a 1-year simulation of Automatic Generation Control dynamics. It can be concluded that the compliance with performance standards is strongly related to the storage capacity, regardless of how fast the device can inject or withdraw power from the grid. Previous results in the state-of-the-art overlook the quantification of this relationship between compliance with performance standards and storage capacity.
Characteristics of Waste Generated in Dimension Stone Processing
Authors: Strzałkowski Paweł
Published: November 2021

Natural dimension stone processing generates large volumes of stone waste, which have a significant impact on the environment, as well as on the efficiency and profitability of the stone-processing plant. The article presents the characteristics of waste produced as a result of natural dimension stone processing and the structure of the waste production process. Solid stone scraps and sludge were distinguished. On the basis of the performed analyses, it was shown that stone waste constitutes 10–35% in relation to the quantity of the processed stone material, with the quantity of sludge being even threefold greater than the volume of solid scraps. According to the circular economy principles, the aim should be to reduce the amount of waste generated by reducing primary resources in favour of secondary material. Reducing the volume of stone waste is possible through rational planning of stone production while at the same time maximising the efficiency of stone material usage and introducing the most modern processing machines. This significant volume of stone waste encourages efforts to find solutions for both its management and reduction. This paper reviews the utility potential of stone waste. Sensible use of waste is important to increase the profitability and productivity of processing plants while incentivising environmental protection.
Employer Expectations Regarding the Competencies of Employees on the Energy Market in Poland
Authors: Szydło Robert , Wiśniewska Sylwia , Tyrańska Małgorzata , Dolot Anna , Bukowska Urszula , Koczyński Marek
Published: November 2021

It is because of competencies that there is a possibility of ensuring the strategic safety of each country when it comes to energy security. With the vast development of IT and teamwork, there are various competencies needed in the whole energy sector. The aim of this study is to assess the needs of competencies in the Polish energy labor market as well as the trends among hard ad soft skills also in the context of renewable energy sources. Within an exploratory approach, 245 job advertisements were analyzed using various tools, including general descriptive statistics, Shapiro-Wilk, Kruskal–Wallis H and Mann–Whitney U tests, as well as Spearman’s Rho. The research confirmed that teamwork and MS Office are crucial demands of employers. It is also important that the market is diverse when it comes to competence demands, but soft skills are needed in every position, even purely technical ones.
Arbuscular Mycorrhizal Fungi in Agriculture
Authors: Wilkes Thomas I.
Published: November 2021

Arbuscular mycorrhizal (AM) fungi are biotrophic symbionts forming close relationships with an estimated 80% of terrestrial plants suitable as their host. Via an established AM fungal–host relationship, soil-bound nutrients are made available to the host plant through root cortical arbuscules as the site of exchange. At these sites, photosynthetic carbohydrates are provided to the AM fungus—carbohydrates that cannot be produced by the fungus. AM fungal–host symbiosis is very sensitive to soil disturbance, for example, agricultural tillage practices can damage and reduce AM fungal abilities to interact with a host and provide plant growth-promoting properties.
Phytoremediation: The Sustainable Strategy for Improving Indoor and Outdoor Air Quality
Authors: Lee Heayyean , Jun Ziwoo , Zahra Zahra
Published: November 2021

Most of the world’s population is exposed to highly polluted air conditions exceeding the WHO limits, causing various human diseases that lead towards increased morbidity as well as mortality. Expenditures on air purification and costs spent on the related health issues are rapidly increasing. To overcome this burden, plants are potential candidates to remove pollutants through diverse biological mechanisms involving accumulation, immobilization, volatilization, and degradation. This eco-friendly, cost-effective, and non-invasive method is considered as a complementary or alternative tool compared to engineering-based remediation techniques. Various plant species remove indoor and outdoor air pollutants, depending on their morphology, growth condition, and microbial communities. Hence, appropriate plant selection with optimized growth conditions can enhance the remediation capacity significantly. Furthermore, suitable supplementary treatments, or finding the best combination junction with other methods, can optimize the phytoremediation process.
Changes in Long-Term Light Properties of a Mixed Conifer—Broadleaf Forest in Southwestern Europe
Authors: Ruiz de la Cuesta Ignacio , Blanco Juan A. , Imbert J. Bosco , Peralta Javier , Rodríguez-Pérez Javier
Published: November 2021

Natural and anthropogenic factors affect forest structure worldwide, primarily affecting forest canopy and its light properties. However, not only stand-replacing events modify canopy structure, but disturbances of lower intensity can also have important ecological implications. To study such effects, we analyzed long-term changes in light properties of a conifer–broadleaf mixed forest in the Southwestern Pyrenees, placed in the fringe between the Mediterranean and Eurosiberian biogeographical regions. At this site, a thinning trial with different intensities (0%, 20%, and 30–40% basal area removed) took place in 1999 and 2009, windstorms affected some plots in 2009 and droughts were recurrent during the sampling period (2003, 2005, 2011). We monitored light properties during 14 years (2005–2019) with hemispherical photographs. We applied partial autocorrelation functions to determine if changes between years could be attributed to internal canopy changes or to external disturbances. In addition, we mapped the broadleaf canopy in 2003, 2008, and 2016 to calculate broadleaf canopy cover and richness at the sampling points with different buffer areas of increasing surface. We applied generalized linear mixed models to evaluate the effects of light variables on canopy richness and cover. We found that light variables had the most important changes during the period 2008 to 2010, reacting to the changes caused that year by the combined effects of wind and forest management. In addition, we found that an area of 4.0 m radius around the sampling points was the best to explain the relationship between light properties and species richness, whereas a radius of 1.0 m was enough to estimate the relationship between light and canopy cover. In addition, light-related variables such as diffuse light and leaf area index were related to species richness, whereas structural variables such as canopy openness were related to canopy cover. In summary, our study demonstrates that non stand-replacing disturbances such as windstorms, thinning, or droughts can have an important role in modifying structural and light-related canopy properties, which in turn may influence natural processes of stand development and ecological succession.
Effect of Charcoal on the Properties, Enzyme Activities and Microbial Diversity of Temperate Pine Forest Soils
Authors: Lasota Jarosław , Błońska Ewa , Babiak Tomasz , Piaszczyk Wojciech , Stępniewska Hanna , Jankowiak Robert , Boroń Piotr , Lenart-Boroń Anna
Published: November 2021

Relict charcoal hearths (RCHs) increases soil fertility in forest ecosystems. However, the effects of RCHs on the activity and abundance of soil microorganisms remain unknown. In this paper, we analysed the impact of relict charcoal production on the soil enzymatic activity and composition of soil bacterial and fungal communities in Scots pine forests of the Manowo Forest District in northern Poland. Moreover, we determined the effect of relict charcoal production on the soil properties. Our research was conducted by comparing the physical, chemical, enzymatic and microbiological properties of charcoal-enriched and charcoal-free soils. Significant differences in physical properties were found between these two soil types in terms of their structure and water holding capacity. As expected, horizons enriched with charcoal were characterised by a significantly higher organic carbon content (4.7% on average compared to 2.2% in control horizons), and also by a considerably higher content of available phosphorus (an average of 64.07 mg·kg−1 compared to 36.21 mg·kg−1 in the control). Similarly, RCH horizons displayed a higher pH and higher contents of Ca and Na cations. These results indicated that RCH soils provided more favourable conditions for the soil microbiome, as reflected by the higher enzymatic activity and diversity of the microorganisms. Moreover, bacterial and fungal communities in RCH soils were more diverse and had greater species/genera richness, especially in the case of fungi. Members of the genus Rhodoplanes dominated the bacterial community at both RCH and non-RCH sites, followed by Streptomyces, Burkholderia, Skermanella, Tsukamurella and Candidatus Solibacter. Both culture- and next generation sequencing (NGS)-based analyses showed that soil fungal communities were dominated by Ascomycota, with Penicillium as the most abundant genus. Our results showed that hearth soils may represent a significant C pool in the forest ecosystem. This study supports the strategy of safeguarding such charcoal-enriched soils as precious C reservoirs and ecologically important biodiversity hotspots. Moreover, the application of charcoal may effectively increase the microbial diversity of forest soils, especially during the reforestation or re-cultivation of disturbed habitats.
The Use of Remote Sensing Data to Estimate Land Area with Forest Vegetation Cover in the Context of Selected Forest Definitions
Authors: Hycza Tomasz , Kamińska Agnieszka , Stereńczak Krzysztof
Published: November 2021

(1) Background: Like many other countries, Poland is obliged to report forest area to the Climate Convention (UNFCCC Kyoto Protocol) and the Food and Agriculture Organization of the United Nations (FAO/UN). Differences between national and international forest definitions lead to differences between actual and reported forest area. Remote sensing is a useful tool for estimating forest area for reporting purposes. One of the most important parts of the estimation is the choice of a basal area to calculate the percentage of vegetation cover. (2) Methods: Height, crown projection area, and minimum complex area were used to classify the area with forest vegetation. Percentage canopy cover was determined using three different methods based on segmentation polygons, triangular grid and canopy height model pixels. The accuracy of the above methods was verified by manual vectorization performed on a selected set of test plots in the Milicz study area according to the international definitions. The differences were examined using three statistical metrics. (3) Conclusions: This paper compares for the first time methods for determining the area for which canopy cover is calculated (using data from (ALS) and discusses the differences between them in the context of accuracy (the correspondence between the results and the reference data) and the complexity of the process (time and effort required to perform the analysis). This is important in the context of reporting, estimating carbon stocks and biodiversity to mitigate the effects of climate change. Method 2 proved to be the most accurate method, Method 1 was found to be the worst option. Accuracy was better in the case of the Kyoto Protocol definition.
Intelligent Predictive Maintenance (IPdM) in Forestry: A Review of Challenges and Opportunities
Authors: Maktoubian Jamal , Taskhiri Mohammad Sadegh , Turner Paul
Published: November 2021

The feasibility of reliably generating bioenergy from forest biomass waste is intimately linked to supply chain and production processing costs. These costs are, at least in part, directly related to assumptions about the reliability and cost-efficiency of the machinery used along the forestry bioenergy supply chain. Although mechanization in forestry operations has advanced in the last 20 years, it is evident that challenges remain in relation to production capability, standardization of wood quality, and supply guarantee from forestry resources because of the age and reliability of the machinery. An important component in sustainable bioenergy from biomass supply chains will be confidence in consistent production costs linked to guarantees about harvest and haulage machinery reliability. In this context, this paper examines the issue of machinery maintenance and advances in machine learning and big data analysis that are contributing to improved intelligent prediction that is aiding supply chain reliability in bioenergy from woody biomass. The concept of “Industry 4.0” refers to the integration of numerous technologies and business processes that are transforming many aspects of conventional industries. In the realm of machinery maintenance, the dramatic increase in the capacity to dynamically collect, collate, and analyze data inputs including maintenance archive data, sensor-based monitoring, and external environmental and contextual variables. Big data analytics offers the potential to enhance the identification and prediction of maintenance (PdM) requirements. Given that estimates of costs associated with machinery maintenance vary between 20% and 60% of the overall costs, the need to find ways to better mitigate these costs is important. While PdM has been shown to help, it is noticeable that to-date there has been limited assessment of the impacts of external factors such as weather condition, operator experiences and/or operator fatigue on maintenance costs, and in turn the accuracy of maintenance predictions. While some researchers argue these data are captured by sensors on machinery components, this remains to be proven and efforts to enhance weighted calibrations for these external factors may further contribute to improving the prediction accuracy of remaining useful life (RUL) of machinery. This paper reviews and analyzes underlying assumptions embedded in different types of data used in maintenance regimes and assesses their quality and their current utility for predictive maintenance in forestry. The paper also describes an approach to building ‘intelligent’ predictive maintenance for forestry by incorporating external variables data into the computational maintenance model. Based on these insights, the paper presents a model for an intelligent predictive maintenance system (IPdM) for forestry and a method for its implementation and evaluation in the field.
Dynamic Patterns of the Vertical Distribution of Vegetation in Heihe River Basin since the 1980s
Authors: Fan Zemeng
Published: November 2021

The vertical distribution of vegetation in Heihe River Basin has presented a significant dynamic change in the different elevation zones since the 1980s. To explore the dynamic patterns of vegetation types located in the different elevation zones of Heihe River Basin, this study collected 440 field sampling datapoints of vegetation types, remote sensing images, climatic observation data, and DEM and preprocessed them. On the basis of the vegetation distribution and the terrain characteristics of Heihe River Basin, this study classified the vertical distribution of vegetation in Heihe River Basin into six vegetation zones, namely, the oasis farmland and desert zone, desert-steppe zone, dry scrub-steppe zone, mountain forest-steppe zone, subalpine scrub-meadow zone, and alpine cold desert-meadow zone. Moreover, the mean annual biotemperature (MAB) and total annual average precipitation (TAP) were used to analyze the relationship between vegetation change and climate change in the different elevation zones. The results show that the change rate of vegetation was up to 25.75% in Heihe River Basin. The area of vegetation that changed in the oasis farmland and desert zone was the largest (7224 km2), and the rate of vegetation that changed in the mountain forest-steppe zone was up to 56.93%. The mean annual biotemperature (MAB) and total annual average precipitation (TAP) in the six elevation zones showed an increasing trend, in which the increased rate of TAP presented a downward trend with the increase of elevation, and that of MAB showed a continuous upward trend with the increase of elevation. The change rate of vegetation was generally higher than that of MAB and TAP in the low and middle vegetation zones. The influence intensity of human activities on vegetation change in the lower and middle elevation zones of Heihe River Basin was greater than that in the high elevation zone between the 1980s and the 2010s. MAB is the major impact factor to vegetation change in the alpine cold zone of Heihe River Basin.
Combining Landscape Fire Simulations with Stand-Level Growth Simulations to Assist Landowners in Building Wildfire-Resilient Landscapes
Authors: Barreiro Susana , Benali Akli , Rua João C. P. , Tomé Margarida , Santos José L. , Pereira José M. C.
Published: November 2021

The wildfire regime in Portugal has been responsible for millions of hectares of burnt area, and Alvares parish is no exception. In 2017, a severe wildfire burnt 60% of its area. Land abandonment has been increasing since the mid 20th century, and a large fraction of the forest area belongs to quasi-absent landowners. This has given rise to large, almost unbroken expanses of undermanaged forests that, in combination with rugged topography, originates a landscape prone to large, intense wildfires. Thus, a change in landscape composition and structure capable of reducing flammability and promoting fuel discontinuity is urgently needed. A fire spread simulator and a forest growth simulator were combined to show the impact of improving management at landscape level. It was assumed that the probability of large wildfires may be reduced by setting aside forest area for the implementation of a fuel break network (FBN) and increasing the area under sustainable forest management. Three levels of management intensity were simulated by restricting the area of Quasi-absent non-industrial owners to 34.5%, 20.1%, and 8.5% of the Alvares forest area, in favor of increasing the area of active and semi-active non-industrial owners (current, moderate, and high management scenarios). Different FBN extents, representing four levels of network implementation priority were combined with the management levels, resulting in 12 scenarios. To evaluate the impact of fire, simulations assuming no-fire, no-FBN, and current management intensity were performed, whereas the impact of operation costs was assessed assuming reduced costs for silvicultural operations. Per hectare simulations were then scaled up to the parish level and volume harvested and net present values were used to compare the management improvement scenarios. Results showed that fire has major repercussions on forest income, but these impacts can be minimized. Intensifying forest management and implementing the first priority FBN segments originated substantial improvements in financial outcome from timber production, close to those obtained for the full FBN implementation. Results also evidenced contrasting contributions from industrial and non-industrial owners with the later evidencing unbalanced cash-flows derailing the possibility for interesting forest incomes. The coupling of fire and forest growth simulations can be an interesting approach to assess the impact of different management and policy scenarios and inform policies.
Identification of Alnus glutinosa L. and A. incana (L.) Moench. Hybrids in Natural Forests Using Nuclear DNA Microsatellite and Morphometric Markers
Authors: Jurkšienė Girmantė , Tamošaitis Sigitas , Kavaliauskas Darius , Buchovska Jurata , Danusevičius Darius , Baliuckas Virgilijus
Published: November 2021

Two alder species (Alnus glutinosa and A. incana) have overlapping distribution, naturally occur in Lithuania, and are considered ecologically and economically important forest tree species. The objective of our study was to estimate the likelihood of spontaneous hybridizations between native alders in natural stands of Lithuania based on leaf morphology and nuclear microsatellite markers. The sampled trees were assigned to the three taxonomic groups of A. glutinosa, A. incana, and potential hybrids based on the leaf and bark morphological traits. The genetic differentiation and potential hybridization between these three groups was tested based on 15 nSSR markers. We identified studied Alnus spp. individuals as pure species and hybrids. Two microsatellite loci were reported as discriminating well between these species. We concluded that our results showed the highest likelihood of two genetic group structures, a clear genetic differentiation between the morphology-based groups of A. glutinosa and A. incana, and rather variable likelihood values in the putative hybrid group. The results provide important implications for genetic conservation and management of Alnus spp.
Challenges in the Application of Dendrochemistry in Research on Historical Environmental Pollution in an Old Copper Mining Area
Authors: Dobrzańska Joanna , Lochyński Paweł , Kalbarczyk Robert , Ziemiańska Monika
Published: November 2021

This research investigates the long-term environmental impact and historical temporal pollution patterns caused by a former copper mine in Iwiny (south-western Poland) using a dendrochemical approach. An additional aspect of this research was considering the possibility of using the inductively coupled plasma-optical emission spectrometry (ICP-OES) measurement technique as a cheaper alternative to inductively coupled plasma mass spectrometry (ICP-MS) in dendrochemical analyses conducted in copper mining areas. In the study area, a tailings storage facility (TSF) dam failure (1967) took place and the alkaline flotation waste containing high concentration of Cu and Pb are stored. Tree cores from pedunculate oak (Quercus robur L.) were analysed for the content of 11 trace elements (TEs) (Cd, Mn, Ni, Zn, Cr, Co, Pb, Cu, Fe, Al, Ag) using the ICP-OES technique, while tree rings’ widths (TRWs) were also measured. Samples that were most significant in the context of the research goals were verified with the ICP-MS method. The results revealed the strong long-term impact of the copper industry as reflected in a substantial increase in the mean contents of: (1) Mn, Ni, Zn, Cr, Pb, Cu and Fe in industrial vs. control trees, (2) TRWs for control vs. industrial trees. However, the observed patterns of TEs and TRWs did not correspond to the known timing of pollution inputs (mining activity, tailings spill). Peak levels were observed for Zn and Fe after the mine was closed. The lack of new sources of pollution and the temporal relationship strongly suggests that the tree rings recorded the chemical signal of the TSF reclamation (the use of fertilizers and agrotechnical interventions). Patterns of 7 elements were detected in most of the samples by ICP-OES (Co and Cd were not detected, Al and Ag were partly detected), while ICP-MS detected all of the elements. Significant differences were obtained for Ag, Cd, and Co. Despite challenges with the application of dendrochemistry in research on old mining areas (e.g., lack of old trees), it has proved to be a useful tool for investigating the aggregate environmental impact.
Predicting Stand Volume by Number of Trees Automatically Detected in UAV Images: An Alternative Method for Forest Inventory
Authors: Stolle Lorena , Corte Ana Paula Dalla , Sanquetta Carlos Roberto , Behling Alexandre , Hentz Ângela Maria Klein , Eisfeld Rozane de Loyola
Published: November 2021

In this study, we estimate the forest stock volume by multiplying the number of trees detected remotely by the estimated mean individual volume of the population (individual approach). A comparison was made with the conventional inventory method (area approach), which included 100 simulations of a simple random sampling process and a Bootstrap resampling. The study area included three stands: stand 1, 16-year-old pine; stand 2, 7-year-old pine; and stand 3, 5-year-old eucalyptus. A census was carried out in each stand for the variables diameter and total height. Individual volume was estimated by a ratio estimator, and the sum of all volumes was considered as the total parametric volume. The area approach presented parametric values within the confidence interval for 91%, 94%, and 98% of the simulations for the three stands, respectively. The mean relative errors for the area approach were −3.5% for stand 1, 0.3% for stand 2, and −0.9% for stand 3. The errors in stands 1 and 3 were associated with the spatial distribution of the volume. The individual approach proved to be efficient for all stands, and their respective parametric values were within the confidence interval. The relative errors were 1% for stand 1, −0.7% for stand 2, and 1.8% for stand 3. For stand 1 and 3, this approach yielded better results than the mean values obtained by the area approach simulations (Bootstrap resampling). Future research should evaluate other remote sources of data and other forest conditions.
Online Service Function Chain Deployment for Live-Streaming in Virtualized Content Delivery Networks: A Deep Reinforcement Learning Approach
Authors: Cevallos Moreno Jesús Fernando , Sattler Rebecca , Caulier Cisterna Raúl P. , Ricciardi Celsi Lorenzo , Sánchez Rodríguez Aminael , Mecella Massimo
Published: November 2021

Video delivery is exploiting 5G networks to enable higher server consolidation and deployment flexibility. Performance optimization is also a key target in such network systems. We present a multi-objective optimization framework for service function chain deployment in the particular context of Live-Streaming in virtualized content delivery networks using deep reinforcement learning. We use an Enhanced Exploration, Dense-reward mechanism over a Dueling Double Deep Q Network (E2-D4QN). Our model assumes to use network function virtualization at the container level. We carefully model processing times as a function of current resource utilization in data ingestion and streaming processes. We assess the performance of our algorithm under bounded network resource conditions to build a safe exploration strategy that enables the market entry of new bounded-budget vCDN players. Trace-driven simulations with real-world data reveal that our approach is the only one to adapt to the complexity of the particular context of Live-Video delivery concerning the state-of-art algorithms designed for general-case service function chain deployment. In particular, our simulation test revealed a substantial QoS/QoE performance improvement in terms of session acceptance ratio against the compared algorithms while keeping operational costs within proper bounds.
Natural-Fibrous Lime-Based Mortar for the Rapid Retrofitting of Heritage Masonry Buildings
Authors: Vailati Marco , Mercuri Micaela , Angiolilli Michele , Gregori Amedeo
Published: November 2021

The present work aims to define the mechanical behavior of a new composite material for the preservation and enhancement of the vast historical and architectural heritage particularly vulnerable to environmental and seismic actions. The new composite represents a novelty in the landscape of the fibrous mortars and consists of natural hydraulic lime (NHL)-based mortar, strengthened by Sisal short fibers randomly oriented in the mortar matrix. The developed mortar ensures the chemical-physical compatibility with the original features of the historical masonry structures (especially in stone and clay) aiming to pursue the effectiveness and durability of the intervention. The use of vegetal fibers (i.e., the Sisal one) is an exciting challenge for the construction industry considering that they require a lower level of industrialization for their processing, and therefore, their costs are considerably lower, as compared to the most common synthetic/metal fibers. Samples of Sisal-composite are tested in three-point bending, aiming to estimate both their bending stress and fracture energy. Tensile and compressive tests were also performed on the composite samples, while water retention and slump test were performed on the fresh mix. At last, the tensile tests on the Sisal strand were performed to evaluate the tensile stress of both strand and wire. An original mechanical interpretation is proposed to explain two interesting phenomena that arose from the analysis of experimental data. The comparison among the performances of unreinforced and reinforced mortar suggests that the use of short fibers is recommendable as coating in the retrofitting interventions alternatively to the long uni or bi-directional fiber strands adopted in the classic fibrous reinforcement (i.e., FRCM). The proposed composite also ensures mix-independent great workability, excellent ductility, and strength, and it can be considered a promising alternative to the classic fiber-reinforcing systems. As final remarks, the use of fiber F1 (length of 24 mm) with respect to fiber F2 (length of 13 mm) is more recommendable in the retrofitting interventions of historical buildings, ensuring higher strength and/or ductility for the composite.