bluuebunny/crossref_metadata_2025 huggingface dataset:
Calorific Value of Festuca rubra Biomass in the Phytostabilization of Soil Contaminated with Nickel, Cobalt and Cadmium Which Disrupt the Microbiological and Biochemical Properties of Soil
Authors: Wyszkowska Jadwiga , Boros-Lajszner Edyta , Kucharski Jan
Published: May 2022

The choice of optimal plant species for phytoremediation and organic fertilization plays an important role in stabilizing the functions of soils contaminated with heavy metals. The influence of nickel, cobalt and cadmium on the biomass yield and calorific value of Festuca rubra, heavy metal concentrations in soil and plants and the microbiological, biochemical and physicochemical proprieties of soil were analyzed in a pot experiment. The tolerance index (TI) describing Festuca rubra’s ability to tolerate heavy metals, as well as the translocation (TF), accumulation (AF) and bioaccumulation (BF) factors of heavy metals in Festuca rubra were calculated. The experiment was conducted in two series: In soil fertilized and not fertilized with compost. Nickel and cobalt significantly inhibited the growth and development of Festuca rubra. The experiment demonstrated that this plant species can be grown on soil contaminated with heavy metals. Festuca rubra contained on average 46.05% C, 34.59% O, 5.91% H, 3.49% N, 0.19% S and 9.76% ash. Festuca rubra has a stable calorific value which is not affected by heavy metals; therefore, biomass harvested from heavy metal-polluted soil can be used for energy generation. The calorific value of Festuca rubra ranged from 15.924 to 16.790 MJ kg−1 plant d.m., and the heat of combustion from 17.696 to 18.576 MJ kg−1. It has a stable calorific value which is not affected by heavy metals, therefore biomass harvested from heavy metal-polluted soil can be used for energy generation. Festuca rubra is particularly useful for the phytostabilization of soil contaminated with cadmium and cobalt. Compost minimizes the adverse effects of heavy metal pollution on the microbiological, biochemical and physicochemical properties of soil.
Multi-Skin Adaptive Ventilated Facade: A Review
Authors: Andreeva Darya , Nemova Darya , Kotov Evgeny
Published: May 2022

Multi-skin ventilated facades with integrated building elements that respond to climatic conditions (mechanized openings and automatic shading with intelligent control) present the potential of improving overall annual energy savings by adapting the thermal properties of buildings. This paper presents a literature review on multi-skin adaptive ventilated facades. Additionally, this article presents a literature review on building envelopes that contain inner-air layers. The operation modes of the air layer used in building enclosure structures are classified and summarized and the thermal performance and benefits of climate-adaptive facades are discussed and reviewed. The existing operation modes of the air layer used in building envelopes are summarized, outlined and roughly classified into the following types: the enclosed type, the naturally ventilated type and the mechanically ventilated type. One of the sustainable development trends is the investigation and application of energy-efficient climate-adaptive facades. In this study, the energy modeling of a high-rise office building was calculated using the Green Building Studio. The annual energy, the annual CO2 emissions, and life cycle energy for the following three types of facade were estimated: a single-layer facade made of three-layer glass with argon, a double ventilated facade, and a triple ventilated facade with a double chamber. The calculation results show that the annual energy of the building with an adaptive triple-skin facade could be reduced by 15% compared with buildings with a single skin facade.
Charging Mobile Devices in Indoor Environments
Authors: Matos Diogo , Pereira Ricardo A. M. , Ribeiro Helena , Mendes Bernardo , Belo Daniel , Oliveira Arnaldo , Carvalho Nuno Borges
Published: May 2022

Wireless power transfer promises to revolutionize the way in which we use and power mobile devices. However, low transfer efficiencies prevent this technology from seeing wide scale real-world adoption. The aim of this work is to use quasioptics to develop a system composed of a dielectric lens fed by a phased array to reduce spillover losses, increasing the beam efficiency, while working on the antenna system’s Fresnel zone. The DC-RF electronics, digital beamforming and beam-steering by an FPGA, and radiating 4 × 4 microstrip patch phased array have been developed and experimented upon, while the lens has been designed and simulated. This paper details these preliminary results, where the phased array radiation pattern was measured, showing that the beam is being generated and steered as expected, prompting the lens construction for the complete system experimentation.
Design and Control of Brushless DC Motor Drives for Refrigerated Cabinets
Authors: Chao Kuei-Hsiang , Chang Long-Yi , Hung Chih-Yao
Published: May 2022

The purpose of this study is to develop a variable frequency brushless DC motor drive for the compressors of refrigerated cabinets. It is based on the microcontroller unit (MCU) produced by Renesas Co., Ltd. using the space vector pulse width modulation (SVPWM) for the modulation of the inverter. In addition, at the AC power supply side of the inverter developed, a circuit for suppressing electromagnetic interference (EMI) and a power factor corrector (PFC) are integrated to control the power factor (PF) at the AC power supply side to be above 0.95, which is far better than the commercially available inverters with a power factor of only 0.5. Finally, an intelligent variable frequency control approach based on the extension theory is designed to classify the rotational speed difference and the rate of change in rotational speed difference between the rotational speed commands and the actual rotational speed of the compressor into 20 zones. Then, for the rotational speed difference and the rate of change in rotational speed difference actually measured, their correlations to the 20 zone categories are calculated to determine an appropriate rotational speed command. The temperature of the refrigerated cabinets can quickly be determined to reach the set target value. The proposed extension speed control is simple in computation and does not require much learning data, making it easy to implement. Furthermore, the drive developed is verified by actual testing and its performance is compared to the compressor drives of the refrigerated cabinets commercially available. It is proved that the performance of the drives developed is indeed far better than that of the drives commercially available.
Computational Fluid Dynamic Study with Comfort Analysis in Large Atrium of the Angelo Hospital in Venice
Authors: Ferrucci Margherita , Romagnoni Piercarlo , Peron Fabio , Strada Mauro
Published: May 2022

To improve the thermal comfort in the hall of the Angelo Hospital (Venezia) an analysis was developed by using Computation Fluid Dynamics and considering some configurations for the air-conditioning system and for the solar shading devices. The reference configuration consists of the installation of four fan coils in the area coupled with a 3 m high metal casing used for solar shading. Then, three other solutions are proposed: by increasing the number of fan coils and changing their position, by adding some radiant panels arranged on the walls, and by inserting a physical confinement as a lateral confinement. The study consists of three sections. Firstly, a section in which the study area is modelled through a strong simplification that allows to represent only a slice of the domain but to immediately evaluate the role of the casing. A second section in which the area is completely modelled, and a third section in which a comfort evaluation is carried out. The analysis shows that the metal casing brings a substantial benefit due to the solar shielding it causes. The radiant panels cool the area only near the wall. The increasing of the number of the fans leads to an excessively high air speed and localized discomfort due to drafts. The lateral confinement on the north and south side is the one that guarantees better cooling of the study area.
Combined Network Intrusion and Phasor Data Anomaly Detection for Secure Dynamic Control Centers
Authors: Kummerow André , Schäfer Kevin , Gupta Parul , Nicolai Steffen , Bretschneider Peter
Published: May 2022

The dynamic operation of power transmission systems requires the acquisition of reliable and accurate measurement and state information. The use of TCP/IP-based communication protocols such as IEEE C37.118 or IEC 61850 introduces different gateways to launch cyber-attacks and to compromise major system operation functionalities. Within this study, a combined network intrusion and phasor data anomaly detection system is proposed to enable a secure system operation in the presence of cyber-attacks for dynamic control centers. This includes the utilization of expert-rules, one-class classifiers, as well as recurrent neural networks to monitor different network packet and measurement information. The effectiveness of the proposed network intrusion and phasor data anomaly detection system is shown within a real-time simulation testbed considering multiple operation and cyber-attack conditions.
Harvesting Energy from Ocean: Technologies and Perspectives
Authors: Khan Muhammed Zafar Ali , Khan Haider Ali , Aziz Muhammad
Published: May 2022

The optimal utilization of renewable energies is a crucial factor toward the realization of sustainability and zero carbon in a future energy system. Tidal currents, waves, and thermal and salinity gradients in the ocean are excellent renewable energy sources. Ocean tidal, osmotic, wave, and thermal energy sources have yearly potentials that exceed the global power demand of 22,848 TWh/y. This paper extensively reviews the technologies related to energy harvesting from waves, tidal, ocean thermals, and the salinity gradient. Moreover, the socio-economic, social, and environmental aspects of the above technologies are also discussed. This paper provides a better picture of where to invest in the future energy market and highlights research gaps and recommendations for future research initiatives. It is expected that a better insight into ocean energy and a deep understanding of various potential devices can lead to a broader adoption of ocean energy. It is also clear that further research into control strategies is needed. Policy makers should provide financial support for technologies in the demonstration stage and employ road mapping to accelerate the cost and risk reductions to overcome economic hurdles. To identify traditional and online sources on the topic, the authors used electronic databases and keyword searching approaches. Among them, the International Renewable Energy Agency data were the primary database utilized to locate sources.
Dynamic Performance Analysis by Laboratory Tests of a Sustainable Prefabricated Composite Structural Wall System
Authors: Georgantzia Evangelia , Nikolaidis Themistoklis , Katakalos Konstantinos , Tsikaloudaki Katerina , Iliadis Theodoros
Published: May 2022

In recent decades, steel frames infilled with precast load-bearing walls have been successfully employed as lateral load-resisting structural systems in high-rise buildings. This is due to their structural efficiency as outer and major inner facades and to the higher construction speed of the building. This paper presents a detailed experimental investigation of a sustainable, prefabricated, composite structural wall system, using a representative test model named the Precast Concrete Steel Panel-Infilled Steel Frame (PCSP-ISF) in full-scale dimensions and subjected to in-plane cyclic loading. A series of experiments was conducted on critical structural specimens, including three-point bending, concentric axial compression, and diagonal compression, together with additional cycling loading tests on steel connection joint specimens, with the aim of validating the reliability and the structural response of the connections. The resulting test data and the observed failure mechanisms are discussed carefully to optimise the sustainable structural performance of the system. A theoretical approach for the evaluation of the shear capacity of the total frame system is also discussed to expand the experimental results for several numerical and experimental research cases. The failure mechanism of this module was formed by a combination of developed plastic hinges on the steel joints and diagonal cracks on the concrete panel. The obtained hysteretic behavior of the system at a parameter with major impact is mainly analysed and discussed. The outcomes indicate a satisfactory and sustainable seismic performance of the PCSP-ISF model, indicating that it can be a very promising lateral load-resisting system for earthquake-prone regions.
Internal Film Cooling with Discrete-Slot Injection Orifices in Hydrogen/Oxygen Engine Thrust Chambers
Authors: Ma Xingyu , Sun Bing , Liu Di , Wang Taiping
Published: May 2022

In the present study, a hydrogen and oxygen heat-sink engine thrust chamber and the corresponding injection faceplate with discrete slot orifices are devised to study the cooling performance near the faceplate region. Moreover, a set of experiments and numerical simulations are conducted to evaluate the effects of various factors on combustion performance and film cooling efficiency. According to the obtained result, the circumferential cooling efficiency has an M-shaped distribution in the near-injector region. Furthermore, it has been discovered that when the film flow ratio increases, so does the cooling efficiency. This is especially more pronounced in the range of 30–80 mm from the faceplate. The cooling efficiency is found to be proportional to the film flow rate ratio’s 0.4 power. Compared with the slot thickness, the reduction in the slot width is more beneficial in improving the cooling efficiency, and the advantage is more prominent for small film flow ratios. In addition, when the amount of coolant is not enough, the cooling effect of the discrete slot film orifice is better than that of the common cylindrical orifice. The present article demonstrates that setting the area ratio of the adjacent film orifices is an effective way to reduce the uneven circumferential distribution of the wall surface temperature.
Geological Characteristics and Development Techniques for Carbonate Gas Reservoir with Weathering Crust Formation in Ordos Basin, China
Authors: Yan Haijun , Jia Ailin , Guo Jianlin , Meng Fankun , Ning Bo , Xia Qinyu
Published: May 2022

The carbonate gas reservoir is one of the most important gas formation types; it comprises a large proportion of the global gas reserves and the annual gas production rate. However, a carbonate reservoir with weathering crust formation is rare, and it is of significant interest to illustrate the geological characteristics of this kind of formation and present the emerging problems and solution measures that have arisen during its exploitation. Therefore, in this research, a typical carbonate gas reservoir with weathering crust formation that is located in Ordos Basin, China, was comprehensively studied. In terms of formation geology, for this reservoir, the distribution area is broad and there are multiple gas-bearing layers with low abundance and strong heterogeneity, which have led to large differences in gas well production performance. Some areas in this reservoir are rich in water, which seriously affects gas well production. Regarding production dynamics, the main production areas in this gas reservoir have been stable on a scale of 5.5 billion cubic meters for more than a decade, and the peripheral area has been continually evaluated to improve production capacity. Nevertheless, after decades of exploration and development, the main areas of this reservoir are faced with several problems, including an unclear groove distribution, an unbalanced exploitation degree, low formation pressure, and increases in intermittent gas wells. To deal with these problems and maintain the stability of gas reservoir production, a series of technologies have been presented. In addition, several strategies have been proposed to solve issues that have emerged during the exploration and exploitation of peripheral reservoir areas, such as low-quality formation, unclear ancient land and complex formation-water distribution. These development measures employed in the carbonate gas reservoir with weathering crust formation in the Ordos Basin will surely provide some guidance for the efficient exploitation of similar reservoirs in other basins all over the world.
Blockage Corrections for Tidal Turbines—Application to an Array of Turbines in the Alderney Race
Authors: Djama Dirieh Nasteho , Thiébot Jérôme , Guillou Sylvain , Guillou Nicolas
Published: May 2022

Tidal turbines are located in shallow water depths in comparison to their dimensions (15 m-diameter turbines in 40 m depths, typically). Constrained vertically by the water depth and laterally by neighbouring turbines, the flow within a tidal farm is subjected to blockage effects that influence the performance of individual devices. The Betz limit (which is the maximum power extractable from an unconstrained flow) can, therefore, be exceeded as demonstrated by Garrett and Cummins. Thus, beyond a significant blockage ratio, blockage effects should be considered when assessing the energy production of a tidal farm. The actuator disk method is particularly suited to simulate the flow field within an array of turbines under realistic tidal flow conditions. However, the implementation of actuator disks in coastal numerical models relies on relationships that neglect the blockage effects on the thrust and power of devices. We propose here an actuator disk formulation corrected to integrate these effects. This modified formulation, based on the model of Whelan et al., is integrated into a regional implementation of a three-dimensional model Telemac3D targeted towards the Alderney Race (English Channel). The method is applied to two hypothetical tidal farms with aligned and staggered arrangements, respectively. Blockage corrections of the thrust and power coefficients are found to have counterbalanced effects on the array production. Thrust correction results in a noticeable flow reduction within the array. However, the associated decrease of the array production is counterbalanced by the increase of the turbine power coefficient. Blockage corrections were, therefore, found to result in a slight increase, by 3%, of the array production over a mean spring tidal cycle.
Study on the Influence of Organic–Inorganic Interface Properties on Breakdown Strength and Thermal Properties of MgO/PLA Composites
Authors: Huang Rongguo , Feng Jia , Lu Chunguang , Du Bin , Ding Jianyu
Published: May 2022

Polylactic acid (PLA) is expected to be widely used in green power equipment manufacturing due to its good mechanical properties and biodegradability. In this paper, the effects of MgO with different particle sizes and mass fractions on the thermal and electrical properties of PLA composites were studied. The experiment found that with the increase in MgO particle sizes and mass fractions, the thermal conductivity of MgO/PLA composites showed a rising trend, which was up to 165.4% higher than that of pure PLA. However, the heat resistance first increases and then decreases. For the electrical properties of MgO/PLA composites, the breakdown strength and volume resistivity decrease with an increase in MgO particle size and mass fraction. In order to further study the influence mechanism of the introduction of MgO with different particle sizes and mass fractions on the thermal and electrical properties of MgO/PLA composites, molecular dynamics simulation was used to simulate the glass transition temperature (Tg) of PLA composites doped with MgO of different particle sizes, and it was found that MgO doping weakened the movement of the PLA molecular chain segment. Using density functional theory (DFT) calculations, it was found that in the MgO and PLA system, electrons have a tendency to migrate from the PLA matrix to MgO, which causes the formation of electron traps at the inorganic–organic interface and affects its electrical properties. The purpose of this study is to provide a theoretical reference for PLA composites in the manufacture of power equipment.
Enhanced Reactive Power Sharing and Voltage Restoration Based on Adaptive Virtual Impedance and Consensus Algorithm
Authors: Keddar Mohamed , Doumbia Mamadou Lamine , Belmokhtar Karim , Krachai Mohamed Della
Published: May 2022

In this paper, power-sharing management control on an AC islanded microgrid is investigated to achieve accurate reactive power sharing. The droop control method is primarily used to manage the active and reactive power sharing among the DGs in the microgrid. However, the line impedance mismatch causes unbalanced reactive power sharing. As a solution a consensus-based adaptive virtual impedance controller is proposed, where the consensus algorithm is used to set the reactive power mismatch; then a virtual impedance correction term is generated through a proportional-integral controller to eliminate the line impedance mismatch. Thus, reactive power sharing is achieved without knowledge of the line impedances or using a central controller. Moreover, the consensus algorithm is used to restore the AC bus voltage to the nominal value by estimating the DGs average voltage using neighbor communication to compensate for the decreased magnitude of the voltage reference. Matlab/Simulink is used to validate the accuracy of reactive power sharing and voltage restauration achievement of the proposed solution through simulation of different scenarios. In addition, a dSPACE DS1104 is used within a developed experimental testbench based on two parallel DGs to validate the effectiveness of the proposed solution in the real world.
AIS-Based Estimation of Hydrogen Demand and Self-Sufficient Fuel Supply Systems for RoPax Ferries
Authors: Fitz Annika Christine , Gómez Trillos Juan Camilo , Sill Torres Frank
Published: May 2022

The International Maritime Organization (IMO) established new strategies that could lead to a significant reduction in the carbon footprint of the shipping sector to address global warming. A major factor in achieving this goal is transitioning to renewable fuels. This implies a challenge, as not only ship-innovative solutions but also a complete low-carbon fuel supply chain must be implemented. This work provides a method enabling the exploration of the potential of low-carbon fuel technologies for specific shipping routes up to larger sea regions. Several aspects including vessel sizes, impact of weather and shipping routes, emissions savings and costs are considered. The local energy use is determined with proven bottom-up prediction methods based on ship positioning data from the Automatic Identification System (AIS) in combination with weather and ship technical data. This methodology was extended by an approach to the generation of a basic low-carbon fuel system topology that enables the consideration of local demand profiles. The applicability of the proposed approach is discussed at hand via a case study on Roll-on/Roll-off passenger and cargo (RoPax) ferries transitioning from conventional fuels to a compressed hydrogen fuel system. The results indicate a potential reduction in emissions by up to 95% and possible system sizes and costs.
Energy and Conventional and Advanced Exergy Analyses of Low-Temperature Geothermal Binary-Flashing Cycle Using Zeotropic Mixtures
Authors: Zhao Yuan , Du Bowen , Chen Shunyi , Zhao Jun , Guo Zhipeng , Wang Lingbao
Published: May 2022

Due to its deep utilization of geobrine and its high net power output, the binary-flashing cycle (BFC) is deemed to be the future geothermal energy power generation technology. The working fluids considered in present analysis are zeotropic mixtures (R245/R600a). The system thermodynamic model is built, and the energy and conventional and advanced exergy analyses are carried out to reveal the real optimization potential. It is demonstrated that the optimal ranges of R245fa mass fraction and working fluid dryness at the evaporator outlet are 0.30~0.50 and 0.40~0.60, considering the thermodynamic performance and the flammability of the zeotropic mixtures, simultaneously. Conventional exergy analysis indicates that the maximum exergy destruction occurs in the condenser, followed by the expander, evaporator, flashing tank, preheater, high-pressure pump and low-pressure pump. Meanwhile, the advanced exergy analysis reveals that the expander should be given the first priority for optimization, followed by the condenser and evaporator. The BFC has a large potential for improvement due to higher avoidable exergy destruction, about 48.6% of the total system exergy destruction can be reduced. Moreover, the interconnections among system components are not very strong, owing to small exogenous exergy destructions. It also demonstrates the effectiveness of advanced exergy analysis, and the approach can be extended to other energy conversion systems to maximize the energy and exergy savings for sustainable development.
Closed-Loop Adaptive High-Starting Torque Scalar Control Scheme for Induction Motor Variable Speed Drives
Authors: Travieso-Torres Juan Carlos , Duarte-Mermoud Manuel A. , Díaz Matías , Contreras-Jara Camilo , Hernández Francisco
Published: May 2022

This article proposes a closed-loop (CL) high-starting torque (HST) scalar control scheme (SCS) for induction motors (IM). It endows the recently proposed HST-SCS with high-output torque capability beyond starting after using an outer speed control loop feeding an inner current control loop with adaptive controllers. Presenting a cascade normalized adaptive passivity-based controller (N-APBC) for nonlinear systems encompassing the IM allows obtaining this result. It extends the normalized adaptive controller for the cascade case. As a result, it keeps the HST-SCS simple control scheme without needing variable observers or parameter estimators and employing tuning information only from the motor nameplate and datasheet. Test bench experiments with a 10 HP motor validate the proposal’s effectiveness. Comparative experimental results show that the CL HST-SCS has a required stator phase voltage lower than HST-SCS. The CL HST-SCS applies the adaptive starting voltage curve for a more extended time than HST-SCS, from the start to 1.9 s versus 1.2 s, respectively. Hence, CL HST-SCS assures HST not only for starting but almost up to 600 rpm, resulting in a smoother transient behavior than HST-SCS under this speed.
Modeling and Analysis of the Harmonic Interaction between Grid-Connected Inverter Clusters and the Utility Grid
Authors: Ren Lintao , Guo Hui , Dou Zhenlan , Wang Fei , Zhang Lijun
Published: May 2022

The virtual synchronous generator (VSG) is a promising technology for future utility grids, since it can mimic the output characteristics of a synchronous generator, which provides the necessary inertia to a utility grid. However, the large-scale application of VSGs is limited due to the harmonic interaction between VSGs and the utility grid. Therefore, in order to investigate the stability issue as well as improve the practical application for large-scale power stations, the harmonic interaction mechanism between the VSG cluster and the utility grid is addressed. Firstly, the output impedance model of a single VSG is established, and it is found that the resonance frequency is related to parameters including the output filter, controller, and grid impedance. On this basis, the capacitor current control for a grid-connected inverter based on a VSG is proposed to enhance the resonance suppression. Furthermore, the output impedance of the VSG cluster is established, which reveals the harmonic interaction characteristics between the VSG cluster and the utility grid. In addition, in order to suppress the resonance and improve the stability, an inner-loop control strategy of VSG is introduced. Finally, the simulation and experimental results verified the correctness of the established modeling and analysis of the harmonic interaction between the clustered VSGs and the utility grid. The results show that the proposed impedance model is correct and can predict the resonant point accuracy (which is around 2.3 kHz in the simulation and experimental cases). The total harmonic distortion (THD) can be reduced to 3.2% which meets the requirements of IEEE standard 519.
Impact of the COVID-19 Pandemic Crisis on the Efficiency of European Intraday Electricity Markets
Authors: Buescher Jan Niklas , Gottwald Daria , Momm Florian , Zureck Alexander
Published: May 2022

Our goal is to examine the efficiency of different intraday electricity markets and if any of their price prediction models are more accurate than others. This paper includes a comprehensive review of Germany, France, and Norway’s (NOR1) day-ahead and intraday electricity market prices. These markets represent different energy mixes which would allow us to analyze the impact of the energy mix on the efficiencies of these markets. To draw conclusions about extreme market conditions, (i) we reviewed the market data linked to COVID-19. We expected higher volatility in the lockdowns than before and therefore decrease in the efficiency of the prediction models. With our analysis, (ii) we want to draw conclusions as to whether a mix based mainly on renewable energies such as that in Norway implies lower volatilities even in times of crisis. This would answer (iii) whether a market with an energy mix like Norway is more efficient in highly volatile phases. For the analysis, we use data visualization and statistical models as well as sample and out-of-sample data. Our finding was that while the different price and volatility levels occurred, the direction of the market was similar. We could find evidence that our expectations (i–iii) were met.
Integration of Hydrothermal Carbonisation and Anaerobic Digestion for the Energy Valorisation of Grass
Authors: Brown Aaron E. , Hammerton James M. , Camargo-Valero Miller Alonso , Ross Andrew B.
Published: May 2022

The integration of hydrothermal carbonisation (HTC) and anaerobic digestion (AD) can overcome some of the disadvantages of thermal or biological processing alone. This study aims to investigate integrated HTC-AD across a range of integration strategies and HTC processing temperatures (150 °C, 200 °C and 250 °C) to improve the energy conversion efficiency (ECE) of grass, compared to AD alone. The separation of hydrochars (HCs) for combustion and process waters (PWs) for digestion appears to be the most energetically feasible HTC-AD integration strategy, compared to HC or HTC-slurry AD. Hydrochars represent the greater energy carrier with between 81–85% of total energy output. The ECE of grass was improved from 51% to 97% (150 °C), 83% (200 °C) and 68% (250 °C) through integrated HTC-AD. Therefore, lower HTC processing temperatures yield more favourable energetics. However, higher HTC temperatures favour more desirable HC properties as a combustion fuel. The hydrochar produced at 250 °C (HC-250) displayed the highest HHV (25.8 MJ/kg) and fixed carbon: volatile matter ratio (0.47), as well as the greatest reduction in slagging and fouling potential (ash flow temperature > 1550 °C). Overall, integrated HTC-AD is an effective energy valorisation strategy for grass. A compromise exists between the quality of hydrochar and the energetic balance. However, at 250 °C the process remains energetically feasible (EROI = 2.63).
An Adaptive Tracking-Extended Kalman Filter for SOC Estimation of Batteries with Model Uncertainty and Sensor Error
Authors: Ma Deng , Gao Kai , Mu Yutao , Wei Ziqi , Du Ronghua
Published: May 2022

Accurate state of charge (SOC) plays a vital role in battery management systems (BMSs). Among several developed SOC estimation methods, the extended Kalman filter (EKF) has been extensively applied. However, EKF cannot achieve valid estimation when the model accuracy is inadequate, the noise covariance matrix is uncertain, and the sensor has large errors. This paper makes two contributions to overcome these drawbacks: (1) A variable forgetting factor recursive least squares (VFFRLS) is proposed to accomplish parameters identification. This method updates the forgetting factor according to the innovation sequence, which accuracy is superior to the forgetting factor recursive least squares (FFRLS); (2) an adaptive tracking EKF (ATEKF) is proposed to estimate the SOC of the battery. In ATEKF, the error covariance matrix is adaptively corrected according to the innovation sequence and correction factor. The value of the correction factor is related to the actual error. Proposed algorithms are validated with a publicly available dataset from the University of Maryland. The experimental results indicate that the identification error of VFFRLS can be reduced from 0.05% to 0.018%. Additionally, ATEKF has better accuracy and robustness than EKF when having large sensor errors and uncertainty of the error covariance matrix, in which case it can reduce SOC estimation error from 1.09% to 0.15%.
What Is the Relationship between Natural Protected Areas and Stakeholders? Based on Literature Analysis from 2000–2021
Authors: Zhang Yangyang , Xu Jiaoyang , Yao Yunong , Yan Zhaogui , Teng Mingjun , Wang Pengcheng
Published: May 2022

The establishment of natural protected areas (NPAs) is an effective means to deal with the degradation of ecosystems caused by climate change and human activities. The area and number of NPAs in the world have shown an obvious growth trend, and their development has ushered in a new bottleneck. More importantly, the management quality of NPAs should be improved, and the key to improving management quality lies in human beings, but the stakeholder groups involved in NPAs are often overlooked by policymakers. In this study, a quantitative review of the global scientific literature on NPAs stakeholders was conducted using a bibliometric approach. The research hotspots and trends, number, time, and countries were analyzed based on data from published articles. The stakeholder types and internal relationships in NPAs were summarized and mapped. The common problems of resources and community resident management among stakeholders were discussed. A total of 5584 research articles selected from the Web of Science core collection database were used as data sources and were visualized using VOSviewer and the Biblioshiny program in the R language. The results of the study help to reveal the mutual influence mechanism between stakeholders during the development of nature reserves and contribute to the sustainable development of global protected areas and human well-being.
Forest Area, CO2 Emission, and COVID-19 Case-Fatality Rate: A Worldwide Ecological Study Using Spatial Regression Analysis
Authors: Li Hansen , Zhang Guodong , Cao Yang
Published: May 2022

Spatial analysis is essential to understand the spreading of the COVID-19 pandemic. Due to numerous factors of multi-disciplines involved, the current pandemic is yet fully known. Hence, the current study aimed to expand the knowledge on the pandemic by exploring the roles of forests and CO2 emission in the COVID-19 case-fatality rate (CFR) at the global level. Data were captured on the forest coverage rate and CO2 emission per capita from 237 countries. Meanwhile, extra demographic and socioeconomic variables were also included to adjust for potential confounding. Associations between the forest coverage rate and CO2 emission per capita and the COVID-19 CFR were assessed using spatial regression analysis, and the results were further stratified by country income levels. Although no distinct association between the COVID-19 CFR and forest coverage rate or CO2 emission per capita was found worldwide, we found that a 10% increase in forest coverage rates was associated with a 2.37‰ (95%CI: 3.12, 1.62) decrease in COVID-19 CFRs in low-income countries; and a 10% increase in CO2 emission per capita was associated with a 0.94‰ (95%CI: 1.46, 0.42) decrease in COVID-19 CFRs in low-middle-income countries. Since a strong correlation was observed between the CO2 emission per capita and GDP per capita (r = 0.89), we replaced CO2 emission with GDP and obtained similar results. Our findings suggest a higher forest coverage may be a protective factor in low-income countries, which may be related to their low urbanization levels and high forest accessibilities. On the other hand, CO2 can be a surrogate of GDP, which may be a critical factor likely to decrease the COVID-19 CFR in lower-middle-income countries.
Evaluating Ecotourism Sustainability Indicators for Protected Areas in Tehran, Iran
Authors: Sobhani Parvaneh , Esmaeilzadeh Hassan , Sadeghi Seyed Mohammad Moein , Marcu Marina Viorela , Wolf Isabelle D.
Published: May 2022

Ecotourism in protected areas facilitates responsible travel to natural places that conserve the environment, deliver economic benefits to local communities, and offer interpretation and education to visitors. Proper planning and sufficient monitoring of ecotourism sustainability indicators is needed to manage visitor activities in protected areas. Therefore, identifying the major impacts and mitigating them in the early stages of ecotourism development could contribute significantly to the achievement of sustainable development. There is a current gap between the situation in the field and academic contributions to this problem in protected areas of Iran. In the present study, we evaluated ecotourism sustainability levels in four different types of protected areas in Iran, including Lar National Park, Jajrud Protected Area with Sustainable Use of Natural Resource Areas, Tangeh Vashi National Natural Monument, and Kavdeh Wildlife Refuge. We developed a comprehensive list of ecotourism sustainability indicators, including 38 indicators in the environmental–physical dimension, 42 indicators in the demographic–social dimension, and 30 indicators in the economic–institutional dimension. Harnessing local community expertise, we adopted a Delphi approach to determine sustainability levels and factors impacting sustainability. Ecotourism in Lar National Park was most sustainable because of the high levels of restrictions protecting the area and the difficulty in access. Conversely, ecotourism sustainability was lowest at Tangeh Vashi National Natural Monument, which allowed for an uncontrolled influx of visitors. We discuss further factors that impact sustainability, such as population growth, expanding urbanization, an increase in physical and economic activities, and extended annual periods of ecotourism activities. Although the presented ecotourism sustainability indicators are specific to Iran, this study can also be seen to provide a template to plan for sustainable ecotourism in other countries. Altogether, our results suggest conducting a type-by-type analysis of the particular circumstances of various protected areas.
Fuelwood Production and Carbon Sequestration in Public Urban Green Spaces in Bulawayo, Zimbabwe
Authors: Ngulani Thembelihle , Shackleton Charlie M.
Published: May 2022

Trees in public urban green spaces provide a variety of ecosystem goods and services that are greatly appreciated by urban residents. A commonly used good, especially in Global South regions, is that of fuelwood for household energy needs. Yet the production potential of fuelwood from public urban green spaces has rarely been examined. This study quantifies the fuelwood production and allied carbon sequestration potential of 12 public urban green spaces in Bulawayo (Zimbabwe) stratified across neighborhoods of different housing densities. We estimated tree density in the green spaces by means of line transects, and annual production through estimates of the mean annual increment of a sample of marked trees. We found that Bulawayo’s public green spaces produce 1.9 t/ha/yr of fuelwood with a value of $340 to $490/ha/yr, and that production varied across spaces and housing density neighborhoods. This production is much lower than the documented demand but it is likely to be significant for fuelwood-dependent households. In contrast, the amount (1010 ± 160 kg/ha/yr) and value (US$4.04/ha/yr) of carbon sequestration were lower. Formal public green spaces produced more fuelwood as compared to informal green spaces and no difference was evident in tree growth rates between exotic and indigenous tree species. This is one of the first studies to show the value of the fuelwood production and carbon sequestration potential of public green spaces in the region and continent and requires that they are integrated into public urban green space policies, planning, and management in the city.
Biosynthesis and Production of Class II Bacteriocins of Food-Associated Lactic Acid Bacteria
Authors: Zhang Tingting , Zhang Yu , Li Lin , Jiang Xiuqi , Chen Zhuo , Zhao Fan , Yi Yanglei
Published: May 2022

Bacteriocins are ribosomally synthesized peptides made by bacteria that inhibit the growth of similar or closely related bacterial strains. Class II bacteriocins are a class of bacteriocins that are heat-resistant and do not undergo extensive posttranslational modification. In lactic acid bacteria (LAB), class II bacteriocins are widely distributed, and some of them have been successfully applied as food preservatives or antibiotic alternatives. Class II bacteriocins can be further divided into four subcategories. In the same subcategory, variations were observed in terms of amino acid identity, peptide length, pI, etc. The production of class II bacteriocin is controlled by a dedicated gene cluster located in the plasmid or chromosome. Besides the pre-bacteriocin encoding gene, the gene cluster generally includes various combinations of immunity, transportation, and regulatory genes. Among class II bacteriocin-producing LAB, some strains/species showed low yield. A multitude of fermentation factors including medium composition, temperature, and pH have a strong influence on bacteriocin production which is usually strain-specific. Consequently, scientists are motivated to develop high-yielding strains through the genetic engineering approach. Thus, this review aims to present and discuss the distribution, sequence characteristics, as well as biosynthesis of class II bacteriocins of LAB. Moreover, the integration of modern biotechnology and genetics with conventional fermentation technology to improve bacteriocin production will also be discussed in this review.
Adaptive User Profiling in E-Commerce and Administration of Public Services
Authors: Gatziolis Kleanthis G. , Tselikas Nikolaos D. , Moscholios Ioannis D.
Published: May 2022

The World Wide Web is evolving rapidly, and the Internet is now accessible to millions of users, providing them with the means to access a wealth of information, entertainment and e-commerce opportunities. Web browsing is largely impersonal and anonymous, and because of the large population that uses it, it is difficult to separate and categorize users according to their preferences. One solution to this problem is to create a web-platform that acts as a middleware between end users and the web, in order to analyze the data that is available to them. The method by which user information is collected and sorted according to preference is called ‘user profiling‘. These profiles could be enriched using neural networks. In this article, we present our implementation of an online profiling mechanism in a virtual e-shop and how neural networks could be used to predict the characteristics of new users. The major contribution of this article is to outline the way our online profiles could be beneficial both to customers and stores. When shopping at a traditional physical store, real time targeted “personalized” advertisements can be delivered directly to the mobile devices of consumers while they are walking around the stores next to specific products, which match their buying habits.
A Survey on Memory Subsystems for Deep Neural Network Accelerators
Authors: Asad Arghavan , Kaur Rupinder , Mohammadi Farah
Published: May 2022

From self-driving cars to detecting cancer, the applications of modern artificial intelligence (AI) rely primarily on deep neural networks (DNNs). Given raw sensory data, DNNs are able to extract high-level features after the network has been trained using statistical learning. However, due to the massive amounts of parallel processing in computations, the memory wall largely affects the performance. Thus, a review of the different memory architectures applied in DNN accelerators would prove beneficial. While the existing surveys only address DNN accelerators in general, this paper investigates novel advancements in efficient memory organizations and design methodologies in the DNN accelerator. First, an overview of the various memory architectures used in DNN accelerators will be provided, followed by a discussion of memory organizations on non-ASIC DNN accelerators. Furthermore, flexible memory systems incorporating an adaptable DNN computation will be explored. Lastly, an analysis of emerging memory technologies will be conducted. The reader, through this article, will: 1—gain the ability to analyze various proposed memory architectures; 2—discern various DNN accelerators with different memory designs; 3—become familiar with the trade-offs associated with memory organizations; and 4—become familiar with proposed new memory systems for modern DNN accelerators to solve the memory wall and other mentioned current issues.
Stability Analysis of Thin Power-Law Fluid Film Flowing down a Moving Plane in a Vertical Direction
Authors: Liu Wu-Man , Chen Cha’o-Kuang
Published: May 2022

This paper analyses the stability of thin power-law fluid flowing down a moving plane in a vertical direction by using the long-wave perturbation method. Linear and nonlinear stability are discussed. The linear stable region increases as the downward speed increases and the power-law index increases. More accurate results are obtained on the coefficients of the nonlinear generalized kinematic equation in the power-law part. The regions of sub-critical instability and absolute stability are expanded when the downward movement of plane increases, or the power-law index increases, and meanwhile the parts of supercritical stability and explosive supercritical instability are compressed. By substituting the power-law index and moving speed into the generalized nonlinear kinematic equation of the power-law film on the free surface, the results can be applied to estimate the stability of the thin film flow in the field of engineering.