bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimal N Application Rates on Switchgrass for Producers and a Biorefinery
Authors: Robertson Keven Alan , English Burton C. , Clark Christopher D. , Thompson Jada M. , Jensen Kimberly L. , Menard Robert Jamey , Labbé Nicole
Published: November 2021

This study analyzes the effects of N fertilizer application rates on profitability of growing switchgrass and using the feedstock in a pyrolysis biorefinery facility to create a source of sustainable aviation fuel (SAF) supply in Tennessee. Switchgrass (Panicum virgatum L.) is a perennial bunchgrass native to North America with traits suitable for biofuel and co-product production. Previous chemical analysis has shown that ash content in switchgrass is related to the amount of nitrogen applied to the field, while at the biorefinery level, the percentage ash content reduces the biorefinery fuel output. To obtain optimal nitrogen (N) application rates for the switchgrass producers and the biorefinery, a two-part analysis is employed. First, a partial budgeting profitability analysis is conducted for this cropping enterprise at the farm-gate level without considering downstream implications of biomass quality, i.e., ash content. Second, the effects of higher ash content as a percentage of the feedstock on biorefinery output are analyzed. Results show farm-gate profit is maximized when N fertilizer is applied at 111 kg/ha, while as a result of increased production levels and decreased percentage ash content, biorefinery profit is maximized when N is applied at 157 kg/ha. Lower ash could lead to premium prices paid to switchgrass producers if higher quality feedstock were to be demanded as part of an integrated biofuel industry.
Isolated Areas Consumption Short-Term Forecasting Method
Authors: Guerard Guillaume , Pousseur Hugo , Taleb Ihab
Published: November 2021

Forecasting consumption in isolated areas represents a challenging problem typically resolved using deep learning or huge mathematical models with various dimensions. Those models require expertise in metering and algorithms and the equipment needs to be frequently maintained. In the context of the MAESHA H2020 project, most of the consumers and producers are isolated. Forecasting becomes more difficult due to the lack of external data and the significant impact of human behaviors on those small systems. The proposed approach is based on data sequencing, sequential mining, and pattern mining to infer the results into a Hidden Markov Model. It only needs the consumption and production curve as a time series and adapts itself to provide the forecast. Our method gives a better forecast than other prediction machines and deep-learning methods used in literature review.
Assessment of Organic Rankine Cycle Part-Load Performance as Gas Turbine Bottoming Cycle with Variable Area Nozzle Turbine Technology
Authors: Motamed Mohammad Ali , Nord Lars O.
Published: November 2021

Power cycles on offshore oil and gas installations are expected to operate more at varied load conditions, especially when rapid growth in renewable energies puts them in a load-following operation. Part-load efficiency enhancement is advantageous since heat to power cycles suffer poor efficiency at part loads. The overall purpose of this article is to improve part-load efficiency in offshore combined cycles. Here, the organic Rankine bottoming cycle with a control strategy based on variable geometry turbine technology is studied to boost part-load efficiency. The Variable Area Nozzle turbine is selected to control cycle mass flow rate and pressure ratio independently. The design and performance of the proposed working strategy are assessed by an in-house developed tool. With the suggested solution, the part-load organic Rankine cycle efficiency is kept close to design value outperforming the other control strategies with sliding pressure, partial admission turbine, and throttling valve control operation. The combined cycle efficiency showed a clear improvement compared to the other strategies, resulting in 2.5 kilotons of annual carbon dioxide emission reduction per gas turbine unit. Compactness, autonomous operation, and acceptable technology readiness level for variable area nozzle turbines facilitate their application in offshore oil and gas installations.
Experimental Study on the Stability and Transient Behavior of a Closed-Loop Two-Phase Thermosyphon (CLTPT) Charged with NOVEC 649
Authors: Larrañaga Ana , Gómez Miguel A. , Patiño David , Porteiro Jacobo
Published: November 2021

Currently, the growing need for efficient refrigeration resources in the industrial sector has led to an increasing interest in finding technologies with a higher heat removal potential and better cooling performance. Along these lines, two-phase liquid cooling appears to be a very interesting solution, with the CLTPT (closed-loop two-phase thermosyphon) being one of the leading alternatives. Most works in the scientific literature study loop thermosyphons that work in flow boiling conditions in steady state. The present paper analyzes the transient thermal behavior of a pool boiling CLTPT gravitational channel as a passive cooling system using NOVEC 649 as working fluid. The evaporator works with two submerged cylindrical heaters that represent different heat sources located in different positions. The initial transient behavior and consequent instabilities of a laboratory-scale facility were studied, followed by a stability analysis for various power inputs. Parameters such as temperature and pressure along the experimental setup were monitored, and the effects of internal pressure and room conditions were also tested. The results show some instabilities in the process to start the flow circulation and a relative stability and quick adaptation to changes when circulation is reached. The temperature in the evaporator chamber was highly homogeneous during the whole process; however, the temperature changes in the riser and the loop top were delayed with respect to the evaporator zone. The analysis shows several pressure and temperature raises before the vapor flux reaches the condenser. When the flow circulation is established, the system becomes highly stable and thermally homogeneous, decreasing the thermal resistance when increasing the power input. The stability analysis also showed that, when the system reaches the steady state, the changes in the power input produce a transient increase in the pressure and temperature of the fluid, followed by a quick decrease of the previous steady state values. The heat transfer analysis in the evaporator shows a higher heat flux on the upper heater caused by the buoyancy flow that rises from the lower heater. It was also observed that the lower heater reaches the CHF point with a lower heat flux.
A Unified Controller for Multi-State Operation of the Bi-Directional Buck–Boost DC-DC Converter
Authors: Broday Gabriel R. , Damm Gilney , Pasillas-Lépine William , Lopes Luiz A. C.
Published: November 2021

DC grid interfaces for supercapacitors (SCs) are expected to operate with a wide range of input voltages with fast dynamics. The class-C DC-DC converter is commonly used in this application because of its simplicity. However, it does not work if the output voltage (V2) becomes smaller than the input voltage (V1). The non-isolated bi-directional Buck–Boost DC-DC converter does not have this limitation. Its two half-bridges provide a means for controlling the power flow operating in the conventional dual-state mode, as well as multi-state, tri, and quad modes. These can be used for mitigating issues such as the Right Half Plane (RHP) zero that has a negative impact on the dynamic response of the system. Multi-state operation typically requires multi-variable control, which is not easy to realize with conventional PI-type controllers. This paper proposes a unified controller for multi-state operation. It employs a carrier-based modulation scheme with three modulation signals that allows the converter to operate in all four possible states and eight different modes of operation. A mathematical model is developed for devising a multi-variable control scheme using feedback linearization. This allows the design of control loops with simple PI controllers that can be used for all multi-state modes under a wide range of operating conditions with the same performance. The proposed scheme is verified by means of simulations.
High Dispersion of CeO2 on CeO2/MgO Prepared under Dry Conditions and Its Improved Redox Properties
Authors: Taira Kenji , Murao Reiko
Published: November 2021

Suppressing the usage of rare-earth elements is crucial for making the catalysts sustainable. Preparing CeO2 nanoparticles is a common technique to reduce CeO2 consumption, but such nanoparticles are prone to sinter or react with the supports when subjected to heat treatments. This study demonstrated that stable CeO2 nanoparticles were deposited on MgO by the simple impregnation method. When CeO2/MgO was prepared under the dry atmosphere, the CeO2 nanoparticles remained ~3 nm in diameter even after being heated at 800 °C, which is much smaller than ~5 nm of CeO2/MgO prepared under ambient air. Temperature-programmed reduction, temperature-programmed oxidation, X-ray photoelectron spectroscopy, and in situ X-ray diffraction studies showed that CeO2/MgO exhibited higher oxygen mobility when prepared under the dry atmosphere. Dry reforming reaction demonstrated that CeO2/MgO prepared under the dry atmosphere exhibited higher activity than that prepared under ambient air and pure CeO2.
Optimal Portfolio Selection Methodology for a Demand Response Aggregator
Authors: Ovalle Pedro Nel , Vuelvas José , Fajardo Arturo , Correa-Flórez Carlos Adrián , Ruiz Fredy
Published: November 2021

This paper presents a methodology for determining the optimal portfolio allocation for a demand response aggregator. The formulation is based on Day-Ahead electricity prices, in which the aggregator coordinates a set of residential consumers that are recruited through contracts. Four types of contracts are analyzed, considering both direct and indirect demand response programs. The objective is to compare different scenarios for contract portfolios in order to establish the benefits of each market agent. An optimization problem is formulated to capture the interactions between the aggregator and end consumers. The model is formulated as a mathematical program with equilibrium constraints: At the upper level, the aggregator maximizes its benefits, whereas the lower level represents the consumers’ contracts. By applying the developed methodology, the characterization of the consumers’ behavior is established in order to forecast their responses to the generation of punctual incentives, both for usual scenarios and peak events, as well as to evaluate the impact that direct and indirect control contracts have on the performance of the aggregator as the energy price varies.
Design and Implementation of an Electric Skibus Line in North Italy
Authors: Leone Carola , Sturaro Laura , Geroli Giacomo , Longo Michela , Yaici Wahiba
Published: November 2021

To enhance the current Public Transport (PT) service in the northern Italian region of Lombardy, this work tries to plan fully a new electric Skibus line connecting the cities of Santa Caterina and Livigno. As a first try outside the city environment, the electrification study is set on a limited mountain zone hence featured by steep grades and cold temperatures. In the first part of the paper, the energy consumed by an electric bus working in such a context is assessed, and from the learned outcomes, proper charging infrastructure is proposed. From the found results, the introduction of a new electric bus line in the chosen region seems feasible. Finally, in the last part of the work the performances of an electric bus fleet are compared with that of a diesel one, in terms of fuel costs and Well-to-Wheel (WTW) emissions. The results prove that an electric fleet would be more convenient for both the economic and the environmental aspects.
Simulation-Assisted Determination of the Start-Up Time of a Polymer Electrolyte Fuel Cell
Authors: Bodner Merit , Penga Željko , Ladreiter Walter , Heidinger Mathias , Hacker Viktor
Published: November 2021

Fuel starvation is a major cause of anode corrosion in low temperature polymer electrolyte fuel cells. The fuel cell start-up is a critical step, as hydrogen may not yet be evenly distributed in the active area, leading to local starvation. The present work investigates the hydrogen distribution and risk for starvation during start-up and after nitrogen purge by extending an existing computational fluid dynamic model to capture transient behavior. The results of the numerical model are compared with detailed experimental analysis on a 25 cm2 triple serpentine flow field with good agreement in all aspects and a required time step size of 1 s. This is two to three orders of magnitude larger than the time steps used by other works, resulting in reasonably quick calculation times (e.g., 3 min calculation time for 1 s of experimental testing time using a 2 million element mesh).
Application of State Estimation in Distribution Systems with Embedded Microgrids
Authors: Manousakis Nikolaos M. , Korres George N.
Published: November 2021

In this paper, a weighted least square (WLS) state estimation algorithm with equality constraints is proposed for smart distribution networks embedded with microgrids. Since only a limited number of real-time measurements are available at the primary or secondary substations and distributed generation sites, load estimates at unmeasured buses remote from the substations are needed to execute state estimation. The load information can be obtained by forecasted and historical data or smart real-time meters. The proposed algorithms can be applied in either grid-connected or islanded operation mode and can efficiently identify breaker status errors at the main substations and feeders, where sufficient measurement redundancy exists. The impact of the accuracy of real and pseudo-measurements on the estimated bus voltages is tested with a 55-bus distribution network including distributed generation.
Review on the Sources of Power Loss in Monofacial and Bifacial Photovoltaic Technologies
Authors: da Silva Michelle Kitayama , Gul Mehreen Saleem , Chaudhry Hassam
Published: November 2021

An evaluation of the degradation effects on photovoltaic modules is essential to minimise uncertainties in the system operation. Bifacial photovoltaic technology is attracting attention due to the capacity of generating energy from the front and rear sides. This paper presents a review of degradation factors, for both conventional monofacial and bifacial photovoltaic modules, to highlight how the current and voltage characteristics of these technologies are affected by degradation. Microcracking, encapsulant discoloration, and light induced degradation seem to have similar effects on both modules. Contrarily, bifacial modules are more prone to potential induced degradation as the electromagnetic shielding is affected by the bifaciality. Bifacial devices are less affected by light and elevated temperature induced degradation. The degradation (1.3%) is similar for both technologies, up to 40 kWh/m2 of solar radiation. Above this value, monofacial degradation increases faster, reaching values of 7%. For tilted systems, the front side soiling degradation of 0.30% per day is similar for both technologies. For vertical systems, soiling loss for bifacial is considerably lower with values of 0.02% per day.
Adaptive Tracking Method of Distorted Voltage Using IMM Algorithm under Grid Frequency Fluctuation Conditions
Authors: Nie Haoyao , Nie Xiaohua
Published: November 2021

This paper newly proposes an interactive multiple model (IMM) algorithm to adaptively track distorted AC voltage with the grid frequency fluctuation. The usual tracking methods are Kalman filter (KF) algorithm with a fixed frequency and KF algorithm with frequency identifier. The KF algorithm with a fixed frequency has a larger covariance parameter to guarantee the tracking robustness. However, it has a large tracking error. The KF algorithm with frequency identifier overly depends on the accuracy and stability of frequency identifier. The advantage of the proposed method is that it is decoupled from frequency detection and does not depend on frequency detection accuracy. First, the orthogonal vector dynamic (OVD) tracking model of the sine wave is established. Then, a model set covering the grid frequency fluctuation range is formed, and a new OVD-IMM tracking algorithm is proposed in combination with IMM algorithm. In the end, the effectiveness and accuracy of the proposed OVD-IMM algorithm are verified through simulations and experiments.
Electric Mobility in Portugal: Current Situation and Forecasts for Fuel Cell Vehicles
Authors: Ala Guido , Colak Ilhami , Di Filippo Gabriella , Miceli Rosario , Romano Pietro , Silva Carla , Valtchev Stanimir , Viola Fabio
Published: November 2021

In recent years, the growing concern for air quality has led to the development of sustainable vehicles to replace conventional internal combustion engine (ICE) vehicles. Currently, the most widespread technology in Europe and Portugal is that of Battery Electric Vehicles (BEV) or plug-in HEV (PHEV) electric cars, but hydrogen-based transport has also shown significant growth in the commercialization of Fuel Cell Electric Vehicles (FCEV) and in the development of new infrastructural schemes. In the current panorama of EV, particular attention should be paid to hydrogen technology, i.e., FCEVs, which is potentially a valid alternative to BEVs and can also be hybrid (FCHEV) and plug-in hybrid (FCPHEV). Several sources cited show a positive trend of hydrogen in the transport sector, identifying a growing trend in the expansion of hydrogen infrastructure, although at this time, it is still at an early stage of development. At the moment, the cost of building the infrastructure is still high, but on the basis of medium/long-term scenarios it is clear that investments in hydrogen refueling stations will be profitable if the number of Fuel Cell vehicles increases. Conversely, the Fuel Cell vehicle market is hampered if there is no adequate infrastructure for hydrogen development. The opportunity to use Fuel Cells to store electrical energy is quite fascinating and bypasses some obstacles encountered with BEVs. The advantages are clear, since the charging times are reduced, compared to charging from an electric charging post, and the long-distance voyage is made easier, as the autonomy is much larger, i.e., the psycho-sociological anxiety is avoided. Therefore, the first part of the paper provides an overview of the current state of electric mobility in Portugal and the strategies adopted by the country. This is necessary to have a clear vision of how a new technology is accepted by the population and develops on the territory, that is the propensity of citizens to technological change. Subsequently, using current data on EV development and comparing information from recent years, this work aims to investigate the future prospects of FCEVs in Portugal by adopting a dynamic model called SERA (Scenario Evaluation and Regionalization Analysis), with which it is possible to identify the Portuguese districts and cities where an FC charging infrastructure is expected to be most beneficial. From the results obtained, the districts of Lisbon, Porto and Aveiro seem to be the most interested in adopting FC technology. This analysis aims to ensure a measured view of the credible development of this market segment.
Harmonic Profile Enhancement of Grid Connected Fuel Cell through Cascaded H-Bridge Multi-Level Inverter and Improved Squirrel Search Optimization Technique
Authors: Choudhury Subhashree , Acharya Shiba Kumar , Khadanga Rajendra Kumar , Mohanty Satyajit , Arshad Jehangir , Ur Rehman Ateeq , Shafiq Muhammad , Choi Jin-Ghoo
Published: November 2021

The generation of energy by conventional systems leads to several environmental issues. Fuel Cell (FC), being a new renewable energy source, has emerged as one of the promising alternatives to obtain clean and efficient energy generation. This paper highlights the power quality enhancement of the grid connected FC through a boost converter and 25 level Cascaded H-Bridge (CHB) Multi-Level Inverter (MLI) using the classical PID controller. To drive the MLI connected to the grid for governing the Point of Common Coupling (PCC) voltage between the FC and the grid, two PID controllers have been utilized. The conventional evolutionary techniques such as Particle Swarm Optimization (PSO) and Squirrel Search Algorithm (SSA) are implemented to tune the PID controllers for dynamic operations. To further enhance the convergence speed of computation and precision of the classical techniques used, an Improved Squirrel Search Algorithm (ISSA) has been proposed in this work. The grid connected power network considered for study here is designed using MATLAB/Simulink environment. Moreover, the system is led to various rigorous voltage sag and swell conditions to test the effectiveness of the proposed controller. A detailed comparison between the conventional PID, PSO, SSA, and proposed ISSA techniques in voltage profile improvement, power quality enhancement, and reduced execution time has been featured. The results obtained highlight the proposed technique’s superiority over the classical methods in terms of improved dynamic voltage response, enhanced power quality, and reduced harmonics. The power quality indices are found out using Total Harmonic Distortion (THD) analysis. The values found out are well within the IEEE-547 indices for the proposed controller, thus justifying its real-time implementation.
Photovoltaic Power Quality Analysis Based on the Modulation Broadband Mode Decomposition Algorithm
Authors: Wang Zucheng , Peng Yanfeng , Liu Yanfei , Guo Yong , Liu Yi , Geng Hongyan , Li Sai , Fan Chao
Published: November 2021

The Broadband Mode Decomposition (BMD) method was previously proposed to solve the Gibbs phenomenon that occurs during photovoltaic signal decomposition; its main idea is to build a dictionary which contains signal features, and to search in the dictionary to solve the problem. However, BMD has some shortcomings; especially if the relative bandwidth of the decomposed signal is not small enough, it may treat a square wave signal as several narrowband signals, resulting in a deviation in the decomposition effect. In order to solve the problem of relative bandwidth, the original signal is multiplied by a high-frequency, single-frequency signal, and the wideband signal is processed as an approximate wideband signal. This is the modulation broadband mode decomposition algorithm (MBMD) proposed in this article. In order to further identify and classify the disturbances in the photovoltaic direct current (DC) signal, the experiment uses composite multi-scale fuzzy entropy (CMFE) to calculate the components after MBMD decomposition, and then uses the calculated value in combination with the back propagation (BP) neural network algorithm. Simulation and experimental signals verify that the method can effectively extract the characteristics of the square wave component in the DC signal, and can successfully identify various disturbance signals in the photovoltaic DC signal.
Advanced Machine Learning Functionalities in the Medium Voltage Distributed Monitoring System QuEEN: A Macro-Regional Voltage Dips Severity Analysis
Authors: Zanoni Michele , Chiumeo Riccardo , Tenti Liliana , Volta Massimo
Published: November 2021

This paper presents the integration of advanced machine learning techniques in the medium voltage distributed monitoring system QuEEN. This system is aimed to monitor voltage dips in the Italian distribution network mainly for survey and research purposes. For each recorded event it is able to automatically evaluate its residual voltage and duration from the corresponding voltage rms values and provide its “validity” (invalidating any false events caused by voltage transformers saturation) and its “origin”(upstream or downstream from the measurement point) by proper procedures and algorithms (current techniques). On the other hand, in the last years new solutions have been proposed by RSE to improve the assessment of the validity and origin of the event: the DELFI classifier (DEep Learning for False voltage dips Identification) and the FExWaveS + SVM classifier (Features Extraction from Waveform Segmentation + Support Vector Machine classifier). These advanced functionalities have been recently integrated in the monitoring system thanks to the automated software tool called QuEEN PyService. In this work, intensive use of these advanced techniques has been carried out for the first time on a significant number of monitored sites (150) starting from the data recorded from 2018 to 2021. Besides, the comparison between the results of the innovative technique (validity and origin of severe voltage dips) with respect to the current ones has been performed at the macro-regional level too. The new techniques are shown to have a not negligible impact on the severe voltage dips number and confirm a non-homogenous condition among the Italian macro-regional areas.
Mobile Nuclear-Hydrogen Synergy in NATO Operations
Authors: Gryz Jarosław , Król Krzysztof , Witkowska Anna , Ruszel Mariusz
Published: November 2021

An uninterrupted chain of energy supplies is the core of every activity, without exception for the operations of the North Atlantic Treaty Organization. A robust and efficient energy supply is fundamental for the success of missions and a guarantee of soldier safety. However, organizing a battlefield energy supply chain is particularly challenging because the risks and threats are particularly high. Moreover, the energy supply chain is expected to be flexible according to mission needs and able to be moved quickly if necessary. In line with ongoing technological changes, the growing popularity of hydrogen is undeniable and has been noticed by NATO as well. Hydrogen is characterised by a much higher energy density per unit mass than other fuels, which means that hydrogen fuel can increase the range of military vehicles. Consequently, hydrogen could eliminate the need for risky refuelling stops during missions as well as the number of fatalities associated with fuel delivery in combat areas. Our research shows that a promising prospect lies in the mobile technologies based on hydrogen in combination with use of the nuclear microreactors. Nuclear microreactors are small enough to be easily transported to their destinations on heavy trucks. Depending on the design, nuclear microreactors can produce 1–20 MW of thermal energy that could be used directly as heat or converted to electric power or for non-electric applications such as hydrogen fuel production. The aim of the article is to identify a model of nuclear-hydrogen synergy for use in NATO operations. We identify opportunities and threats related to mobile energy generation with nuclear-hydrogen synergy in NATO operations. The research presented in this paper identifies the best method of producing hydrogen using a nuclear microreactor. A popular and environmentally “clean” solution is electrolysis due to the simplicity of the process. However, this is less efficient than chemical processes based on, for example, the sulphur-iodine cycle. The results of the research presented in this paper show which of the methods and which cycle is the most attractive for the production of hydrogen with the use of mini-reactors. The verification criteria include: the efficiency of the process, its complexity and the residues generated as a result of the process (waste)—all taking into account usage for military purposes.
Optimization and Field Test of a Chelating Acid System for Scaled Gas Wells in the Hechuan Gas Field
Authors: Li Qiang , Fan Zhenzhong , Liu Qingwang , Liu Guohong , Ma Wenhai , Li Junliang , Li Nan , Ma Pingang
Published: November 2021

The Hechuan gas field is one of the tight gas reservoirs with the highest formation water salinity in China. The content of metal ions, such as calcium, magnesium, iron, and barium, is as high as 20 g/L. Severe scales in near-wellbore reservoir blocks the gas and liquid flow paths, affecting the normal production of gas wells. The analysis of scale samples shows that the scale compositions in the Hechuan gas field are complex, which are composed of calcium carbonate, calcium sulfate, barium sulfate, iron salt, silicate, and other inorganic scales. To dissolve these scales, 14 kinds of laboratory self-made chelating acids named AST-01 to AST-14, sequentially, were evaluated by the descaling rate, in which the chelating acid AST-01 was selected with a dissolution rate of 77.7%. Meanwhile, the optimal concentration and reaction time of AST-01 were investigated, and the concentrations of the corrosion inhibitor, the iron ion stabilizer, and surfactants were also optimized. Then, a chelating acid descaling formula was obtained, which was 15~20% of AST-01 chelating acid + 1.5~2.0% of corrosion inhibitor + 2.5% of iron ion stabilizer + 0.3% of drainage aid. A pilot field trial of this descaling formula was applied in a Hechuan X1 well. A remarkable result was obtained in that the shut-in tubing pressure recovery rate was increased by 14 times, the gas production was increased by 10 times, and the gas well resumed to produce continuously again.
Targeted CRISPR/Cas9-Based Knock-Out of the Rice Orthologs TILLER ANGLE CONTROL 1 (TAC1) in Poplar Induces Erect Leaf Habit and Shoot Growth
Authors: Fladung Matthias
Published: November 2021

Pyramidal-, erect- or upright-growing plant forms are characterized by narrow branch angles of shoots and leaves. The putative advantage of upright-leaf and shoot habit could be a more efficient penetration of light into lower canopy layers. Pyramidal genotypes have already been reported for various tree genotypes including peach. The paralogous rice ortholog TILLER ANGLE CONTROL 1 (TAC1) has been proposed to be the responsible gene for upright growth. However, it has not really been demonstrated for any of the pyramidal tree genotypes that a knock-out mutation of the TAC1 gene is causing pyramidal plant growth. By in silico analyses, we have identified a putative rice TAC1 ortholog (Potri.014G102600, “TAC-14”) and its paralog (Potri.002G175300, “TAC-2”) in the genome of P. trichocarpa. Two putative PcTAC1 orthologs in the P. × canescens clone INRA 717-1B4 were successfully knocked-out by applying a transgenic CRISPR/Cas9-approach. The mutants were molecularly analyzed and phenotyped over a period of three years in a glasshouse. Our results indicate that the homozygous knock-out of “TAC-14” is sufficient to induce pyramidal plant growth in P. × canescens. If up to twice as many pyramidal individuals were planted on short rotation coppices (SRCs), this could lead to higher wood yield, without any breeding, simply by increasing the number of trees on a default field size.
The Relationship between Landscape Metrics and Facial Expressions in 18 Urban Forest Parks of Northern China
Authors: Liu Ping , Liu Mengnan , Xia Tingting , Wang Yutao , Guo Peng
Published: November 2021

Urban forests are an important green infrastructure that positively impacts human well-being by improving emotions and reducing psychological stress. Questionnaires have been used frequently to study the influence of forest experiences on mental health; however, they have poor controllability and low accuracy for detecting immediate emotions. This study used the alternative approach of facial reading, detecting the facial expressions of urban forest visitors and their relationships with the landscape metrics. Using the microblogging site, Sina Weibo, we collected facial photos of 2031 people visiting 18 different forest parks across Northern China in 2020. We used satellite imagery analysis to assess the elevation and pattern sizes of green space and blue space areas. Age and location were taken as independent variables affecting facial expressions, which were categorized as happy or sad. With increases in green space and intact park areas, people showed a higher frequency of expressing happy scores. The results showed that the forest experience frequently elicited positive emotions, suggesting that creating and maintaining urban green spaces enhance people’s quality of life.
Urban Forests and Landscape Ecology
Authors: Esperon-Rodriguez Manuel , Harrison Tina
Published: November 2021

Urbanization has become a dominant driver of landscape transformation across the world, with cities representing centers of economic and socio-cultural development [...]
Recent Advances in the Monitoring, Assessment and Management of Forest Pathogens and Pests
Authors: Moricca Salvatore , Panzavolta Tiziana
Published: November 2021

Tree pathogens and pests are fundamental components of forest ecosystems. By killing and decomposing susceptible trees, they regulate the cycle of nutrients and energy flow, thus shaping the structure and composition of forest stands. However, ecosystems can be seriously disrupted when the population density of these parasites increases beyond their tolerance level. Ascertaining the origin of pathogen and pest outbreaks, recognizing their causal agents in a precise and unequivocal way, while understanding their reproductive and dispersive dynamics are all crucial for the implementation of effective control measures. The studies collected in this special issue cover a wide range of topics in the field of forest pathology and entomology. Investigations range from molecular diagnosis of pathogens and pests to their monitoring and quantification in the field, from measurements of their proliferation rate to the analysis of their genetic variability, from the assessment of the role of plant diversity and ecosystem heterogeneity on pathogen and pest impacts to disease and pest management. Specific case studies show how applied research conducted with innovative methods is key to solving taxonomic issues that were, until now, controversial. The variety of experimental approaches and the range of scientific issues addressed document the trends and topicality of modern forest health protection science.
Recreational Services from Green Space in Beijing: Where Supply and Demand Meet?
Authors: Chen Tianyu , Zhao Yu , Yang He , Wang Guangyu , Mi Feng
Published: November 2021

Green space, mainly forests, shrubs, and grasslands, provides essential ecosystem services for human well-being. Based on multi-source data and using the Maximum Entropy model and Geographical Information System (GIS) tools, this research comprehensively assesses the supply and demand of recreational services from green space in Beijing. The supply of recreational services in Beijing is influenced by natural and human factors, showing large spatial variability. The supply level of mountainous areas with good natural geographical conditions and intact ecological landscape is significantly higher than that of plain areas with reduced vegetation and overexploitation. Residents have a high demand for recreational services in green space landscape and low demand in non-green space landscape. The quantitative balance pattern of supply and demand varies greatly, and most areas show the state of undersupply. The spatial matching pattern of supply and demand varies significantly too, and the mismatch is apparent. Spatial allocation should be more carefully considered than the aggregated supply and demand. Differentiated development strategies such as ecological reshaping, ecological development, restoration, and protection should be implemented for different areas in the future of planning and management in urban green areas. This will optimize and balance the supply-demand matching pattern for recreational services and promote the effective improvement of ecosystem service functions and residents’ ecological welfare.
Evaluation of Six Satellite-Based Terrestrial Latent Heat Flux Products in the Vegetation Dominated Haihe River Basin of North China
Authors: Li Yufu , Sui Xinxin , Yao Yunjun , Cheng Haixia , Zhang Lilin , Wang Lu , Ning Jing , Shang Ke , Yang Junming , Yu Ruiyang , Liu Lu , Guo Xiaozheng , Xie Zijing
Published: November 2021

In this study, six satellite-based terrestrial latent heat flux (LE) products were evaluated in the vegetation dominated Haihe River basin of North China. These LE products include Global Land Surface Satellite (GLASS) LE product, FLUXCOM LE product, Penman-Monteith-Leuning V2 (PML_V2) LE product, Global Land Evaporation Amsterdam Model datasets (GLEAM) LE product, Breathing Earth System Simulator (BESS) LE product, and Moderate Resolution Imaging Spectroradiometer (MODIS) (MOD16) LE product. Eddy covariance (EC) data collected from six flux tower sites and water balance method derived evapotranspiration (WBET) were used to evaluate these LE products at site and basin scales. The results indicated that all six LE products were able to capture the seasonal cycle of LE in comparison to EC observations. At site scale, GLASS LE product showed the highest coefficients of determination (R2) (0.58, p < 0.01) and lowest root mean square error (RMSE) (28.2 W/m2), followed by FLUXCOM and PML products. At basin scale, the LE estimates from GLASS product provided comparable performance (R2 = 0.79, RMSE = 18.8 mm) against WBET, compared with other LE products. Additionally, there was similar spatiotemporal variability of estimated LE from the six LE products. This study provides a vital basis for choosing LE datasets to assess regional water budget.
BpTCP3 Transcription Factor Improves Salt Tolerance of Betula platyphylla by Reducing Reactive Oxygen Species Damage
Authors: Ren Li , Li Fangrui , Jiang Jing , Li Huiyu
Published: November 2021

The plant-specific transcription factors TEOSINTE BRANCHED1/CYCLO IDEA/PROLIFERATING CELL FACTOR1 (TCP) act as developmental regulators that have many roles in the growth and development processes throughout the entire life span of plants. TCP transcription factors are responsive to endogenous and environmental signals, such as salt stress. However, studies on the role of the TCP genes in salt stress response have rarely focused on woody plants, especially forest trees. In this study, the BpTCP3 gene, a CYC/TB1 subfamily member, isolated from Betula platyphylla Sukaczev, was significantly influenced by salt stress. The β-glucuronidase (GUS) staining analysis of transgenic B. platyphylla harboring the BpTCP3 promoter fused to the reporter gene GUS (pBpTCP3::GUS) further confirmed that the BpTCP3 gene acts a positive regulatory position in salt stress. Under salt stress, we found that the BpTCP3 overexpressed lines had increased relative/absolute high growth but decreased salt damage index, hydrogen peroxide (H2O2), and malondialdehyde (MDA) levels versus wild-type (WT) plants. Conversely, the BpTCP3 suppressed lines exhibited sensitivity to salt stress. These results indicate that the BpTCP3 transcription factor improves the salt tolerance of B. platyphylla by reducing reactive oxygen species damage, which provides useful clues for the functions of the CYC/TB1 subfamily gene in the salt stress response of B. platyphylla.
Micropropagation, Characterization, and Conservation of Phytophthora cinnamomi-Tolerant Holm Oak Mature Trees
Authors: Martínez Mª Teresa , Arrillaga Isabel , Sales Ester , Pérez-Oliver María Amparo , González-Mas Mª del Carmen , Corredoira Elena
Published: November 2021

Holm oak populations have deteriorated drastically due to oak decline syndrome. The first objective of the present study was to investigate the use of axillary budding and somatic embryogenesis (SE) to propagate asymptomatic holm oak genotypes identified in disease hotspots in Spain. Axillary budding was achieved in two out of six tolerant genotypes from the south-western region and in two out of four genotypes from the Mediterranean region. Rooting of shoots cultured on medium supplemented with 3 mg L−1 of indole-3-acetic acid plus 0.1 mg L−1 α-naphthalene acetic acid was achieved, with rates ranging from 8 to 36%. Shoot cultures remained viable after cold storage for 9–12 months; this procedure is therefore suitable for medium-term conservation of holm oak germplasm. SE was induced in two out of the three genotypes tested, by using nodes and shoot tips cultured in medium without plant growth regulators. In vitro cloned progenies of the tolerant genotypes PL-T2 and VA5 inhibited growth of Phytophthora cinnamomi mycelia when exposed to the oomycete in vitro. Significant differences in total phenol contents and in the expression profiles of genes regulating phenylpropanoid biosynthesis were observed between in vitro cultured shoots derived from tolerant trees and cultures established from control genotypes.
Impacts of Forest Fire on Understory Species Diversity in Canary Pine Ecosystems on the Island of La Palma
Authors: Weiser Frank , Sauer Anna , Gettueva Daria , Field Richard , Irl Severin D. H. , Vetaas Ole , Chiarucci Alessandro , Hoffmann Samuel , Fernández-Palacios José María , Otto Rüdiger , Jentsch Anke , Provenzale Antonello , Beierkuhnlein Carl
Published: November 2021

Forest fires are drivers of spatial patterns and temporal dynamics of vegetation and biodiversity. On the Canary Islands, large areas of pine forest exist, dominated by the endemic Canary Island pine, Pinus canariensis C. Sm. These mostly natural forests experience wildfires frequently. P. canariensis is well-adapted to such impacts and has the ability to re-sprout from both stems and branches. In recent decades, however, anthropogenically caused fires have increased, and climate change further enhances the likelihood of large forest fires. Through its dense, long needles, P. canariensis promotes cloud precipitation, which is an important ecosystem service for the freshwater supply of islands such as La Palma. Thus, it is important to understand the regeneration and vegetation dynamics of these ecosystems after fire. Here, we investigated species diversity patterns in the understory vegetation of P. canariensis forests after the large 2016 fire on the southern slopes of La Palma. We analyzed the effect of fire intensity, derived from Sentinel-2 NDVI differences, and of environmental variables, on species richness (alpha diversity) and compositional dissimilarity (beta diversity). We used redundancy analysis (dbRDA), Bray–Curtis dissimilarity, and variance partitioning for this analysis. Fire intensity accounted for a relatively small proportion of variation in alpha and beta diversity, while elevation was the most important predictor. Our results also reveal the important role of the endemic Lotus campylocladus ssp. hillebrandii (Christ) Sandral & D.D.Sokoloff for understory diversity after fire. Its dominance likely reduces the ability of other species to establish by taking up nutrients and water and by shading the ground. The mid- to long-term effects are unclear since Lotus is an important nitrogen fixer in P. canariensis forests and can reduce post-fire soil erosion on steep slopes.
Climate Change and Air Pollution Effect on Forest Ecosystems
Authors: Badea Ovidiu
Published: November 2021

Climate change, air pollution, urbanization, globalization, demographic changes and changing consumption patterns affect forests and their social, cultural, ecological and economic functions, resulting in consequences for the social value of forests and for people’s livelihoods, health and quality of life [...]
Effect of an Ectomycorrhizal Fungus on the Growth of Castanea henryi Seedlings and the Seasonal Variation of Root Tips’ Structure and Physiology
Authors: Xiong Huan , Chen Ping , Chen Wangzun , Yang Yinghui , Jin Yijia , Tian Shiyi , Masabni Joseph , Yuan Deyi , Zou Feng
Published: November 2021

Castanea henryi is a ubiquitous hardwood chestnut species in southern China and is important both ecologically and economically. It is mainly cultivated for nut production, just like other chestnut species. However, the establishment of C. henryi seedlings in a new orchard has proven to be difficult because few seedlings survive transplanting due to the incompatibility of their coarse root architecture with nutrient-depleted red acid soils in southern China. Root architecture can be profoundly modified and nutrient can be stress alleviated due to the association of roots with ectomycorrhizal (ECM) fungi. Boletus edulis is an ECM fungus with edible and medicinal fruiting bodies. However, its impact on plant growth varies with the plant species it is associated with. In order to elucidate the role of B. edulis in C. henryi afforestation, we evaluated growth parameters and soil enzymatic activities, as well as seasonal variations in physiology and structure of ECM root tips. Growth responses and soil enzymatic activities were measured 6 months after inoculation. The physiological characteristics of root tips were also compared at various seasons throughout the year. B. edulis colonization of C. henryi roots was successful at a 60% colonization rate. Height, base diameter, and biomass (especially the underground part) of inoculated seedlings (JG) were higher than those of uninoculated seedlings (CK). JG had higher root total length, root surface area, root volume, root average diameter, and number of root tips than CK. Additionally, JG exhibited higher total nitrogen and phosphorus content. Abnormal mantle and Harting net were observed in winter. No matter the season, ECM tips had higher antioxidant enzyme activities, root activities, soluble protein content, and lower malondialdehyde compared to non-ECM tips (nE) and those without ECM tips (woE), and there were no differences between nE and woE. It is important to understand the growth of the host plant in response to ECM and that the seasonal variation of ECM root tips is important when growing high-quality C. henryi seedlings, due to the crucial role of B. edulis in improving seedling initial survival rate.
Adaptive Multi-Grained Buffer Management for Database Systems
Authors: Wang Xiaoliang , Jin Peiquan
Published: November 2021

The traditional page-grained buffer manager in database systems has a low hit ratio when only a few tuples within a page are frequently accessed. To handle this issue, this paper proposes a new buffering scheme called the AMG-Buffer (Adaptive Multi-Grained Buffer). AMG-Buffer proposes to use two page buffers and a tuple buffer to organize the whole buffer. In this way, the AMG-Buffer can hold more hot tuples than a single page-grained buffer. Further, we notice that the tuple buffer may cause additional read I/Os when writing dirty tuples into disks. Thus, we introduce a new metric named clustering rate to quantify the hot-tuple rate in a page. The use of the tuple buffer is determined by the clustering rate, allowing the AMG-Buffer to adapt to different workloads. We conduct experiments on various workloads to compare the AMG-Buffer with several existing schemes, including LRU, LIRS, CFLRU, CFDC, and MG-Buffer. The results show that AMG-Buffer can significantly improve the hit ratio and reduce I/Os compared to its competitors. Moreover, the AMG-Buffer achieves the best performance on a dynamic workload as well as on a large data set, suggesting its adaptivity and scalability to changing workloads.