bluuebunny/crossref_metadata_2025 huggingface dataset:
Improved Control Technique for Enhancing Power System Stability in Out-of-Step Conditions
Authors: Fose Nande , Krishnamurthy Senthil , Moodley Prathaban
Published: August 2024

From time to time, a series of unpredictable and conflicting contingencies can lead to angular instability of the power system and even blackouts if not adequately handled by an out-of-step (OOS) protection system. The key contribution of this research work, to the theory of out-of-step protection, is the identification and isolation after a given disruption of many unstable swings. This paper presents a proposed method to avoid false operation for distance function by out-of-step blocking to improve the system stability by using optimally placed PMUs for the fast detection of system analogue quantities. The studies were performed on a modified Eskom transmission network in the Western Cape with 765 kV and 400 kV voltage levels. The aim is to investigate the IEC 61850-90-5 standard for predictive dynamic stability maintaining systems using PMUs for out-of-step conditions of synchronous generators. The power system modelling and simulation are performed in the RSCAD-FX for the proposed multi-area power system network. An experimental lab-scale implementation is built to test the proposed out-of-step algorithm in a real-time digital simulator. Software-based PMU is incorporated to test and validate the IEC 61850-90-5 standard sampled values. Simulation and experimental results are presented.
Diagnosing Energy Poverty in Portugal through the Lens of a Social Survey
Authors: Moura Pedro , Fonseca Paula , Cunha Inês , Morais Nuno
Published: August 2024

Energy poverty (EP) is a crucial socio-economic problem in current society, as it deprives people of a basic standard of living and quality of life. In general, EP is linked to various factors, but it is primarily associated with high energy costs, low household income, and inefficient building structures. Due to the recent energy crisis in Europe, the importance of these factors has escalated. Bearing in mind the above remarks, the REVERTER EU-funded LIFE project will develop and test nine roadmaps in four European countries (Brezovo—Bulgaria; Athens Urban area—Greece; Riga—Latvia; and Coimbra—Portugal) to alleviate EP by addressing the poor energy efficiency of dwellings. To directly observe real-life scenarios in designated pilot regions, questionnaire surveys were conducted, involving approximately 300 households in each pilot area. This paper presents and evaluates the outcomes of the survey conducted in the central region of Portugal. The findings allow for a deeper comprehension of the factors that impact energy poverty in Portugal, spanning socio-economic aspects, housing characteristics, mechanical systems, energy expenses, and behaviors, as well as the awareness of available support initiatives. Drawing from the survey’s insights, novel strategies are suggested to alleviate energy poverty, with a primary emphasis on crafting tailored, efficient policies that address the genuine requirements of households and individuals.
Assessment of Boil-Off Losses and Their Cost Implication during Liquid Hydrogen Tank Filling with and without Precooling
Authors: Okpeke Bright Ebikemefa , Ait Aider Cherif , Baetcke Lars , Ehlers Sören
Published: August 2024

During liquid hydrogen bunkering into a cryogenic tank, boil-off losses occur due to the high thermal gradient between liquid hydrogen and the warm surface of the tank. This leads to gaseous hydrogen release. Such losses constitute a significant drawback in using hydrogen as a fuel for maritime applications where bunkering operations are regularly carried out, thereby constituting a significant loss along the liquid hydrogen pathway. Due to the inherently low temperature of liquid hydrogen, boil-off losses are always present. Some boil-off losses cannot be eliminated because they are thermodynamically constrained or intrinsic to the system’s design. Boil-off recovery methods can be implemented to capture the boil-off; however, those solutions come with an additional cost and system complexities. Hence, this paper investigates the feasibility of minimizing boil-off losses during the first bunkering of liquid hydrogen or refilling of liquid hydrogen in an empty cryogenic tank by first precooling the cryogenic tank surface to decrease the thermal gradient between the liquid hydrogen and the tank surface/wall. In this paper, different media for precooling a cryogenic tank are evaluated to assess the boil-off reduction potential and the associated costs in order to identify the most suitable solution. The assessment has been carried out based on analytical formulation.
Thermodynamic Model for Cold-Phase Influence on Light Vehicles’ Fuel Consumption
Authors: Rovai Fernando Fusco , Mady Carlos Eduardo Keutenedjian
Published: August 2024

The present and appropriate concern regarding climate changes resulting from the combustion of fossil fuels in light passenger vehicles raises the necessity to develop appropriate instruments to investigate probable and feasible solutions for fleet decarbonization. Given the direct relationship between fossil fuel consumption and greenhouse gas emissions have historically been determined through experimental tests in the laboratory following standard cycles, to enhance the vehicle’s energy efficiency these should be complemented by numerical simulation tools, as they demonstrate fast response and adequate correlation to experimentation. In this aspect, one of the biggest challenges of numerical simulation is quantifying the impact of the various phenomena that affect the vehicle operation during the cold phase, in which the internal combustion engine loses efficiency. This study proposes a thermodynamic model for simulating the fuel consumption of light vehicles during the cold phase of operation. Measured lubricant temperature, ignition spark retardation, exhaust valve timing, and coolant temperature in the vehicles along the drive cycle are the required input data for the model. This thermodynamic procedure makes it possible to quantify the impact on fuel consumption while driving the vehicle in cold operation. The cold phase, with a 505 s duration, is responsible for approximately a 21% increase in fuel consumption in a standard urban drive cycle. It is considered that the shorter the route, the more pronounced and significant the cold phenomena are, and the impact of vehicles frequently driven on short urban routes can be accurately estimated for future analyses.
The Development of a Malleable Model for Critical System Supervision Integration
Authors: Lisboa Luciano A. C. , Melo Thamiles R. , Campos Ikaro G. S. A. , Aragão Matheus B. , Ribeiro Alexandre S. , Silva Lucas C. , da Silva Valéria L. , Lima Antonio M. N. , Santos Alex A. B.
Published: August 2024

Critical systems, in which failure and malfunction may result in severe human, environmental, and financial damages, are essential components in various sectors and particularly in energy domains. Although undesirable, integration error problems in the supervision of critical systems do occur, incurring significant expenses due to an operator’s subjective analysis and hardware topology failures. In this work, a malleable model design approach is proposed to formulate and solve the integration error problem in critical systems’ supervision in terms of reliability. A real hybrid power plant (HPP) case is considered for a case study with simulated data. A method framework with an informal approach (C4 diagram) and formal approach (hierarchical colored Petri nets) in a radial spectrum is applied to the HPP supervision design. In using formal methods, a formulation and solution to this problem through structured, scalable, and compact mathematical representations are possible. This malleable model is intended to guarantee the functional correctness and also reliability of the plant supervision system based on system software architecture. The outcomes suggest that the malleable model is appropriate for the energy domain and can be used for other types of critical systems, bringing all the benefits of this methodology to the context in which it will be applied.
A Flexible Envelope Method for the Operation Domain of Distribution Networks Based on “Degree of Squareness” Adjustable Superellipsoid
Authors: Wang Kewei , Huang Yonghong , Xu Junjun , Liu Yanbo
Published: August 2024

The operation envelope of distribution networks can obtain the independent p-q controllable range of each active node, providing an effective means to address the issues of different ownership and control objectives between distribution networks and distributed energy resources (DERs). Existing research mainly focuses on deterministic operation envelopes, neglecting the operational status of the system. To ensure the maximization of the envelope operation domain and the feasibility of decomposition, this paper proposes a modified hyperellipsoidal dynamic operation envelopes (MHDOEs) method for distribution networks based on adjustable “Degree of Squareness” hyperellipsoids. Firstly, an improved convex inner approximation method is applied to the non-convex and nonlinear model of traditional distribution networks to obtain a convex solution space strictly contained within the original feasible region of the system, ensuring the feasibility of flexible operation domain decomposition. Secondly, the embedding of the adjustable “Degree of Squareness” maximum hyperellipsoid is used to obtain the total p-q operation domain of the distribution network, facilitating the overall planning of the distribution network. Furthermore, the calculation of the maximum inscribed hyperrectangle of the hyperellipsoid is performed to achieve p-q decoupled operation among the active nodes of the distribution network. Subsequently, a correction coefficient is introduced to penalize “unknown states” during the operation domain calculation process, effectively enhancing the adaptability of the proposed method to complex stochastic scenarios. Finally, Monte Carlo methods are employed to construct various stochastic scenarios for the IEEE 33-node and IEEE 69-node systems, verifying the accuracy and decomposition feasibility of the obtained p-q operation domains.
Evaluation of Changes in the Chemical Composition of Grasses as a Result of the Methane Fermentation Process and Biogas Production Efficiency
Authors: Waliszewska Bogusława , Waliszewska Hanna , Grzelak Mieczysław , Majchrzak Leszek , Gaweł Eliza , Murawski Maciej , Sieradzka Agnieszka , Vaskina Iryna , Spek-Dźwigała Agnieszka
Published: August 2024

Methane fermentation, which is one of the key processes in biogas production, plays an important role in the conversion of biomass to energy. During this process, changes occur in the chemical composition of organic feedstocks, including the chemical composition of grasses. The assessment of these changes is crucial for the efficiency and productivity of biogas production. The material for this study comprised fully mature grass blades with leaves and inflorescences and was collected from extensively used meadows and pastures, as well as cultivated and set-aside areas in the Wielkopolskie Voivodeship, the communes of Białośliwie and Trzcianka, Poland. The aim of this study was to compare methane fermentation efficiency in nine grass species and identify the biomass component involved in biogas production. The results indicate that the fermentation process, as expected, changed the cellulose content. The lignin content of the grasses before fermentation varied more than the cellulose content. The content of holocellulose (sum of carbohydrate components) in the grasses ranged from 59.77 to 72.93% before fermentation. Methane fermentation significantly reduced the carbohydrate content in the grasses, with a low degree of polymerization. Grassland biomass-based biogas production is a viable alternative to conventional fossil fuels.
A Novel Meta-Heuristic Algorithm Based on Birch Succession in the Optimization of an Electric Drive with a Flexible Shaft
Authors: Malarczyk Mateusz , Katsura Seiichiro , Kaminski Marcin , Szabat Krzysztof
Published: August 2024

The paper presents the application of a new bio-inspired metaheuristic optimization algorithm. The popularity and usability of different swarm-based metaheuristic algorithms are undeniable. The majority of known algorithms mimic the hunting behavior of animals. However, the current approach does not satisfy the full bio-diversity inspiration among different organisms. Thus, the Birch-inspired Optimization Algorithm (BiOA) is proposed as a powerful and efficient tool based on the pioneering behavior of one of the most common tree species. Birch trees are known for their superiority over other species in overgrowing and spreading across unrestricted terrains. The proposed two-step algorithm reproduces both the seed transport and plant development. A detailed description and the mathematical model of the algorithm are given. The discussion and examination of the influence of the parameters on efficiency are also provided in detail. In order to demonstrate the effectiveness of the proposed algorithm, its application to selecting the parameters of the control structure of a drive system with an elastic connection is shown. A structure with a PI controller and two additional feedbacks on the torque and speed difference between the drive motor and the working machine was selected. A system with rated and variable parameters is considered. The theoretical considerations and the simulation study were verified on a laboratory stand.
Review on Security Range Perception Methods and Path-Planning Techniques for Substation Mobile Robots
Authors: Zheng Jianhua , Chen Tong , He Jiahong , Wang Zhunian , Gao Bingtuan
Published: August 2024

The use of mobile robots in substations improves maintenance efficiency and ensures the personal safety of staff working at substations, which is a trend in the development of technologies. Strong electric and solid magnetic fields around high-voltage equipment in substations may lead to the breakdown and failure of inspection devices. Therefore, safe operation range measurement and coordinated planning are key factors in ensuring the safe operation of substations. This paper first summarizes the current developments that are occurring in the field of fixed and mobile safe operating range sensing methods for substations, such as ultra-wideband technology, the two-way time flight method, and deep learning image processing algorithms. Secondly, this paper introduces path-planning algorithms based on safety range sensing and analyzes the adaptability of global search methods based on a priori information, local planning algorithms, and sensor information in substation scenarios. Finally, in view of the limitations of the existing range awareness and path-planning methods, we investigate the problems that occur in the dynamic changes in equipment safety zones and the frequent switching of operation scenarios in substations. Furthermore, we explore a new type of barrier and its automatic arrangement system to improve the performance of distance control and path planning in substation scenarios.
A Binary Expansion Approach for the Water Pump Scheduling Problem in Large and High-Altitude Water Supply Systems
Authors: Cariaga Denise , Lorca Álvaro , Anjos Miguel F.
Published: August 2024

The water pump scheduling problem is an optimisation model that determines which water pumps will be turned on or off at each time period over a given time horizon for a given water supply system. This problem has received considerable attention in mining and desalination due to the high power consumption of water pumps and desalination plants and the complicated dynamics of water flows and the power market. Motivated by this, in this paper we solve the optimal operation of a desalinated water supply system consisting of interconnected tanks and pumps that transport water to high-altitude reservoirs. The optimisation of this process encounters several difficulties arising from (i) the nonlinearities of the equations for the frictional losses along the pipes and pumps, which makes the problem a nonlinear mixed-integer model, and (ii) many possible combinations of pressure head and flow rates, which quickly leads to high computational costs. These limitations prevent the problem from being solved in a reasonable computational time in high-altitude water supply systems with more than six pumps and reservoirs, as in many networks worldwide. Therefore, in this work we develop new exact methods for the optimal pump scheduling problem that use a binary expansion approach to efficiently account for the existing nonlinearities by reducing the computational difficulties of the original problem while keeping an excellent representation of the physical phenomena involved. We also extensively tested the proposed approach in different network topologies and a case study for a real-world copper mine water network, and we conclude that the binary expansion approach significantly reduces the computational time for solving the problem with high precision, which can be very relevant for the practical daily operation of real-world water supply systems.
Development of a Series Braking Resistor to Eliminate Control Interference in Multi-Infeed HVDC Systems Considering the AC Three-Phase Fault—An Actual Case Study
Authors: Lee Sungwook , Hong Junho , Kwon Dohoon
Published: August 2024

The integration of converter facilities into power systems has warranted a growing need to address the control interference phenomenon. In this study, we propose a facility-based approach to mitigate the control interference between adjacent high-voltage direct current (HVDC) units in a multi-infeed HVDC system. The proposed method uses a series braking resistor (SeBR) as a preventive measure to restore control when a fault occurs in one HVDC unit within a multi-infeed HVDC system, thereby enabling stable operation of adjacent HVDC units. The developed SeBR model incorporates an inductor component and is divided into Stages 1 and 2 to overcome the frequency reduction issue associated with the long-term deployment of conventional R-based SeBRs. Additionally, if the fault continues to affect the control of adjacent HVDC units despite the application of a blocking stage in the faulted HVDC unit, switch controller logic circuits are designed considering the deployment of Stage 2 of the proposed SeBR. The effectiveness of the proposed SeBR is validated based on the detailed modeling and verification of actual HVDC systems via a case study. The results validate the superior performance of the proposed SeBR over other methods in ensuring a continuous stable operation of the system.
Numerical Study on Internal Flow and Cavitation Characteristics of GDI Injectors for Different Nozzle Orifice Geometries
Authors: Hu Chaoqun , Wu Zhijun , Ferrari Alessandro , Ji Meng , Deng Jun , Vento Oscar
Published: August 2024

The geometry of an orifice is a major determinant of nozzle internal flow and cavitation, which directly govern spray atomization and consequently affect combustion and fuel economy in internal combustion engines. In this study, simulation models of the nozzle at different angles between the normal and the injection hole inlet cross-section and the injection hole axis, as well as with different injection hole cone angles (a positive angle between the injection hole axis and its walls implies a divergent hole), were investigated by means of a previously developed numerical model that was validated based on experimental data from X-ray image technology. The results indicate that as the angle between the normal and the injection hole inlet cross-section and the injection hole axis increases, the cavitation asymmetry within the injection hole intensifies, accompanied by a decrease in the gas volume fraction. On one side of the injection hole, the hydraulic flip width expands, while, on the other side of the injection hole, the flow state gradually changes from hydraulic flip to super-cavitation flow, transitional cavitation and fully reattached flow. The divergent orifice layout intensifies cavitation, and the higher the positive injection hole cone angle, the bigger the hydraulic flip width. The convergent layout of the injection hole suppresses cavitation, and cavitation inside the nozzle disappears completely when the injection hole cone angle is less than −10°.
Global Geopolitical Changes and New/Renewable Energy Game
Authors: Zhao Xuemeng , Huang Weilun
Published: August 2024

This study analyzes the impact of global geopolitical changes on new/renewable energy (NRE) policies and their roles in enhancing national energy security, elevating international stature, and influencing the global energy market. Using game theory, it reveals how NRE policies promote technological innovation, diversify energy supply, and strengthen international collaboration, thus advancing the global energy system towards a low-carbon transition and improving international energy governance. NRE policies significantly enhance national energy security by reducing dependency on single energy sources, facilitate the global shift to low-carbon energy, and intensify international cooperation. The effectiveness of these policies in driving energy transformation is notable, and they are expected to remain crucial for global energy security and sustainable transition. Recommendations include strengthening the stability and security of energy supply chains through enhanced oversight, increasing investment in R&D and innovation to reduce costs, fostering international cooperation for better policy coordination, and implementing diversified energy policies to encourage the adoption of NRE. These measures will address challenges from global geopolitical dynamics and drive the global energy system towards sustainability and efficiency.
Optimization-Based Suppression Method of Oscillations in Photovoltaic Grid-Connected Systems with Controllable Nonlinear Loads
Authors: Zhu Tong , Huang Gechao , Ye Xi , Wang Yanfeng , Ouyang Xuetong , Zhang Weilin , Cheng Yangfan , Wang Yuhong
Published: August 2024

In order to reduce carbon emissions from the power grid, photovoltaic (PV) generation units and controllable nonlinear loads based on power electronic devices are gradually becoming more prevalent in the power system. In a PV grid-connected system featuring controllable nonlinear loads, the interplay among PV grid-connected inverters, the loads, and the grid can potentially lead to voltage oscillations. To tackle this challenge, this paper introduces an optimization-based method for suppressing oscillations, which carefully balances system stability with response performance. Firstly, an impedance model of the system is established by applying the harmonic linearization method, and system stability is analyzed using the “logarithmic frequency stability criterion”. Subsequently, impedance relative sensitivity is used to identify key parameters that affect system stability, and the interaction between key parameters is considered to analyze the stability range for these parameters. On this basis, a parameter optimization method based on the particle swarm optimization algorithm is proposed to balance system stability and response performance. The effectiveness and robustness of this method are verified through a simulation analysis.
Optimizing Piezoelectric Bimorphs for Energy Harvesting from Body Motion: Finger Movement in Computer Mouse Clicking
Authors: Chinachatchawarat Theetuch , Pattarapongsakorn Theerawat , Ploypray Patitta , Jintanawan Thitima , Phanomchoeng Gridsada
Published: August 2024

Electrical devices are integral to daily life, but limited battery life remains a significant issue. A proposed solution is to convert dissipated energy from human motion into electricity using piezoelectric materials. This study investigates lead–zirconate–titanate (PZT) piezoelectric materials in bimorph configuration, conducts performance tests to understand their characteristics and determine the optimal load resistance, and develops an energy-harvesting prototype. Performance tests adjusted input parameters and varied load resistance and input magnitude to optimize power gained from the PZT bimorph. A suitable human movement for the application of the bimorph is a mouse-clicking motion by fingers. A prototype was created by integrating the bimorph into a computer mouse to capture energy from clicks. The results showed that the deformation rate of the PZTs, input magnitude, and resistance load were key factors in optimization. The bimorph configuration produced 0.34 mW of power and 5.5 V at an optimum load of 5072 Ω, requiring less effort to generate electricity. For the computer mouse energy harvester case, it yielded a total average power of approximately 38.4 μW per click with a click frequency of 4 Hz. This power could be used to support IoT devices such as human sensors (e.g., CO2, temperature, and pulse sensors) and smart home sensors, enabling comprehensive health and environmental monitoring. In conclusion, input specifications, magnitude, and load resistance are essential for optimizing piezoelectric energy harvesters.
Synergistic Effects in Co-Gasification of Willow and Cedar Blended Char in CO2 Media
Authors: Koido Kenji , Endo Kenji , Morimoto Hidetsugu , Ohashi Hironori , Sato Michio
Published: August 2024

Willow is a promising biomass resource for addressing the challenges of securing stable domestic biomass fuels in Japan and utilising abandoned agricultural land. Among the willow species, Salix pet-susu Kimura KKD (known as ezonokinu willow, EW) stands out for its growth, high production, storage stability, production stability, and business stability. Previous studies have investigated fuel characterisation through gasification (co-gasification) of various biomass mixtures to enhance feedstock flexibility for gasifier commercialisation. However, the synergistic effects of co-gasification using fuels containing EW blended with Japanese cedar, a commonly planted forest species in Japan, remain unexplored. Therefore, this study explored CO2 co-gasification with different blend ratios of EW/cedar blended char and evaluated the fuel characteristics for each blend ratio to elucidate the synergistic effects. The prepared char samples were utilised in the CO2 gasification test with TG-DTA as the analyser. The results suggest that in the initial stages of the willow/cedar blended char co-gasification reaction, pore size and specific surface area significantly influence the reaction rate. Subsequent stages of the reaction are influenced by the promoting and inhibiting effects of inorganic components, which impact co-gasification. The synergy factor results for the willow/cedar blended char co-gasification suggest a reaction pathway.
Markovian Maintenance Planning of Ship Propulsion System Accounting for CII and System Degradation
Authors: Garbatov Yordan , Georgiev Petar
Published: August 2024

The study’s objective is to create a method to select the best course of maintenance action for each state of ship propulsion system degradation while considering both the present and future costs and associated carbon intensity indicator, CII, rates. The method considers the effects of wind and wave action when considering fouling and ageing. The ship resistance in calm, wave, and wind conditions has been defined using standard operating models, which have also been used to estimate the required engine power, service speed, fuel consumption, generated CO2, CII, and subsequent maintenance costs. The maintenance takes into consideration the effects of profit loss because of lost opportunities and efficiency over time. Any maintenance choice has total costs associated with it, including extra fuel, upkeep, and missed opportunities. Using a discrete-time Markov chain, the ship’s propulsion system maintenance schedule is optimized. A decision has been reached regarding the specific maintenance measures to be undertaken for each state of the Markov chain among various alternatives. The choice of optimal maintenance is related to a Markov decision process and is made by considering both the current and future costs. The developed method can forecast the propulsion system’s future states and any required maintenance activities.
A Study on the Effect of Turbulence Intensity on Dual Vertical-Axis Wind Turbine Aerodynamic Performance
Authors: Yang Yanan , Cao Yang , Qian Zhong , Wang Jian , Zhu Yixian , Chen Xia , Zhang Wendong , Wang Yujie , Wu Guoqing , Chen Shaohua
Published: August 2024

Examining dual vertical-axis wind turbines (VAWTs) across various turbulence scenarios is crucial for advancing the efficiency of urban energy generation and promoting sustainable development. This study introduces a novel approach by employing two-dimensional numerical analysis through computational fluid dynamics (CFD) software to investigate the performance of VAWTs under varying turbulence intensity conditions, a topic that has been relatively unexplored in existing research. The analysis focuses on the self-starting capabilities and the effective utilization of wind energy, which are key factors in urban wind turbine deployment. The results reveal that while the impact of increased turbulence intensity on the self-starting performance of VAWTs is modest, there is a significant improvement in wind energy utilization within a specific turbulence range, leading to an average power increase of 1.41%. This phenomenon is attributed to the more complex flow field induced by heightened turbulence intensity, which delays the onset of dynamic stall through non-uniform aerodynamic excitation of the blade boundary layer. Additionally, the inherent interaction among VAWTs contributes to enhanced turbine output power. However, this study also highlights the trade-off between increased power and the potential for significant fatigue issues in the turbine rotor. These findings provide new insights into the optimal deployment of VAWTs in urban environments, offering practical recommendations for maximizing energy efficiency while mitigating fatigue-related risks.
Experimental Investigation of R404A Indirect Refrigeration System Applied Internal Heat Exchanger: Part 1—Coefficient of Performance Characteristics
Authors: Jeon Min-Ju , Lee Joon-Hyuk
Published: August 2024

In this study, the performance characteristics of an R404A indirect refrigeration system (IRS) applied to an internal heat exchanger (IHX) is evaluated for supermarkets and hypermarkets. In a direct expansion system, R404A is the primary refrigerant and R744, a brine, is the secondary fluid. While there are abundant studies analyzing the theoretical performance of IRS, experimental research on IRS is lacking, and there are no papers that address the results of changes in the IHX in detail. In this study, the results achieved by modifying various parameters are experimentally evaluated to provide fundamental data for designing the optimal IRS. In the main results, looking at the trend of the increase in IHX efficiency, the change is very minimal when the efficiency is above 50%, so it is ideal to apply an IHX efficiency of about 50% considering economics and COP, etc. Applying the results in this study enables the operation and maintenance of IRSs as an eco-friendly system by achieving energy efficiency through optimizing the system coefficient of performance and securing economic feasibility by minimizing the R404A charging amount of the refrigeration cycle. To serve supermarkets and hypermarkets, R744 as a secondary fluid may help to realize an ecologically friendly, compact IRS system with a high heat transfer coefficient that can operate at low temperatures (−35 to 5 °C).
Needle Biomass Turnover Rate in Scots Pine Stands of Different Ages
Authors: Turski Mieczysław , Korczyński Ignacy , Łukowski Adrian , Węgiel Andrzej
Published: August 2024

Understanding needle biomass turnover rates in Scots pine (Pinus sylvestris L.) stands is crucial for modelling forest ecosystem dynamics and nutrient cycling. This study examined needle litterfall and biomass turnover in Scots pine stands of varying ages in temperate forests (western Poland). The research focused on determining how stand age affects needle biomass, litterfall and the associated turnover rates. Data were collected from 20 Scots pine stands aged 26 to 90 years, and needle litterfall was measured and analysed in relation to stand characteristics such as age, density and biomass. The average annual needle litter production of the sampled Scots pine stands was 2008 kg·ha−1·year−1, similar to the values previously reported for this tree species in other temperate forests in Europe. The average needle biomass turnover rate for sampled Scots pine stands was 23.4%. We could not support the hypothesis that this parameter depended on the age of the Scots pine stand. The needle biomass turnover rate showed a positive correlation with crown length and a negative correlation with stand density due to the very weak correlations; however, further research is needed to confirm these relationships. Despite this, the parameter can be used to estimate needle litterfall and can be applicable to conditions corresponding to those of temperate forests in Central and Western Europe. This study also highlights the need for further research on needle biomass turnover in temperate forests to improve the accuracy of carbon and nutrient cycling models. This work contributes to a deeper understanding of the role of needle litterfall in maintaining soil fertility and forest productivity, offering insights into sustainable forest management and conservation strategies.
Distribution Characteristics and Driving Factors of the Bacterial Community Structure in the Soil Profile of a Discontinuous Permafrost Region
Authors: Liu Qilong , Song Liquan , Zou Siyuan , Wu Xiaodong , Zang Shuying
Published: August 2024

Global warming leads to the melting of permafrost, affects changes in soil microbial community structures and related functions, and contributes to the soil carbon cycle in permafrost areas. Located at the southern edge of Eurasia’s permafrost region, the Greater Khingan Mountains are very sensitive to climate change. Therefore, by analyzing the bacterial community structure, diversity characteristics, and driving factors of soil profiles (active surface layer, active deep layer, transition layer, and permafrost layer) in this discontinuous permafrost region, this research provides support for the study of the carbon cycling process in permafrost regions. The results show that the microbial diversity (Shannon index (4.81)) was the highest at 0–20 cm, and the Shannon index of the surface soil of the active layer was significantly higher than that of the other soil layers. Acidobacteria and Proteobacteria were the dominant bacteria in the active layer soil of the permafrost area, and Chloroflexi, Actinobacteria, and Firmicutes were the dominant bacteria in the permafrost layer. Chloroflexi made the greatest contribution to the bacterial community in the permafrost soil, and Bacteroidota made the greatest contribution to the bacterial community in the active surface soil. The structure, richness, and diversity of the soil bacterial community significantly differed between the active layer and the permafrost layer. The number of bacterial species was the highest in the active layer surface soil and the active layer bottom soil. The difference in the structure of the bacterial community in the permafrost soil was mainly caused by changes in electrical conductivity and soil–water content, while that in the active layer soil was mainly affected by pH and soil nutrient indices. Soil temperature, NO3−-N, and pH had significant effects on the structure of the bacterial community. The active layer and permafrost soils were susceptible to environmental information processing and genetic information processing. Infectious disease: the number of bacterial species was significantly higher in the surface and permafrost layers than in the other layers of the soil. In conclusion, changes in the microbial community structure in soil profiles in discontinuous permafrost areas sensitive to climate change are the key to soil carbon cycle research.
Is It Possible to Predict a Forest Insect Outbreak? Backtesting Using Remote Sensing Data
Authors: Kovalev Anton , Tarasova Olga , Soukhovolsky Vladislav , Ivanova Yulia
Published: August 2024

In this study, methods are proposed for analyzing the susceptibility of forest stands to attacks by forest insects on the basis of Earth remote sensing data. As an indicator of the state of forest stands, we proposed to use a parameter of the sensitivity of a vegetation index (normalized difference vegetation index; NDVI) during a vegetative period to changes in the radiative temperature of the territory (land surface temperature; LST) determined from satellite data of the Terra/Aqua system. The indicator was calculated as a spectrum of a response function in an integral equation linking changes of NDVI to those of LST. Backtesting was carried out using data from two outbreaks of the Siberian silk moth Dendrolimus sibiricus Tschetv. and outbreaks of the white mottled sawyer Monochamus urussovi Fischer and of the four-eyed fir bark beetle Polygraphus proximus Blandford in taiga forests of Krasnoyarsk Territory in Russia. In addition, the state of fir stands in the year 2023 was examined when damage to the forest stands was not yet noticeable, but Siberian silk moth adults were found in pheromone traps. It was shown that the proposed indicator of susceptibility of forest stands changed significantly 2–3 years before the pest outbreak in outbreak foci of the studied areas. Thus, the proposed indicator can be used to predict outbreaks of insect pests. The proposed approach differs from commonly used remote sensing methods in that, rather than using absolute values of remote indicators (such as, for example, NDVI), it focuses on indicators of the susceptibility of these remote indicators to the characteristics of the natural environment. Since any given point on the planet is characterized by a seasonally varying temperature, it is always possible to determine the sensitivity of a remote sensing indicator to changes in the environment that are not directly related to the absolute value of the indicator. Future studies are expected to examine susceptibility indices as a function of forest stand location and species, and to examine the length of spatial correlation of susceptibility indices, which may provide information on the possible extent of future insect outbreaks.
Potential of Endophytic Microorganisms in Fermentative Processes Using Agro-Industrial Waste as Substrates
Authors: Leite Neta Maria Terezinha Santos , Sandes Rafael Donizete Dutra , De Jesus Mônica Silva , Araujo Hannah Caroline Santos , Dos Santos Raquel Anne Ribeiro , Santana Luciana Cristina Lins De Aquino , Narain Narendra
Published: August 2024

This study investigated the potential of endophytic microorganisms in fermentative processes using agro-industrial residues as substrates. The aim was to explore sustainable biotechnological methods for producing valuable compounds from waste. Endophytic microorganisms were isolated from strawberry, lychee, and tangerine and used in fermentative processes with passion fruit, guava, and pineapple residues. Key methods included isolating and screening potent aroma-producing microorganisms, identifying them using MALDI-TOF MS, and analyzing volatile compounds by GC-MS. The results identified 37 endophytic microorganisms, with Kloeckera apiculata presenting the greatest aromatic potential. Fermentation with agro-industrial residues produced significant volatile compounds, identifying 27, 23, and 22 compounds from passion fruit, pineapple, and guava residues, respectively. The main conclusions highlighted the high production of ethyl acetate and 2-phenylethyl acetate, which contributed to fruity and floral aromas. The novelty of this study lies in the use of endophytic microorganisms isolated from tropical fruits to biotransform agro-industrial waste into high-value aromatic compounds, offering economic and environmental benefits. This research is significant, as it proposes a sustainable approach to valorize waste and produce natural aroma compounds through biotechnological processes.
Physiological–Biochemical Characteristics and a Transcriptomic Profiling Analysis Reveal the Postharvest Wound Healing Mechanisms of Sweet Potatoes under Ascorbic Acid Treatment
Authors: Xuan Hongxia , Cheng Jiyu , Pang Linjiang , Yin Liqing , Guan Yuge , Cheng Junfeng , Lu Xinghua , Lu Guoquan
Published: August 2024

Sweet potatoes are extremely vulnerable to mechanical wounds during harvesting and postharvest handling. It is highly necessary to take measures to accelerate wound healing. The effect of 20 g L−1 of ascorbic acid (AA) treatment on the wound healing of sweet potatoes and its mechanisms were studied. The results validated that AA treatment significantly reduced the weight loss rate and disease index. AA treatment effectively enhanced the formation speed of lignin and SPP at the wound sites, decreased the MDA content, and maintained the cell membrane integrity. AA enhanced the activities of PAL, C4H, 4CL, CAD, and POD and increased the contents of chlorogenic acid, caffeic acid, sinapic acid, ferulic acid, cinnamic acid, p-coumaryl alcohol, sinapyl alcohol, coniferyl alcohol, and lignin. Based on a transcriptomic analysis, a total of 1200 genes were differentially expressed at the sweet potato wound sites by the AA treatment, among which 700 genes were upregulated and 500 genes were downregulated. The KEGG pathway analysis showed that the differentially expressed genes were mainly involved in phenylalanine, tyrosine, and tryptophan biosynthesis; phenylpropanoid biosynthesis; and other wound healing-related pathways. As verified by a qRT-PCR, the AA treatment significantly upregulated the gene expression levels of IbSKDH, IbADT/PDT, IbPAL, and Ib4CL at the wound sties.
Development and Evaluation of a Dry Emulsion of Ostrich Oil as a Dietary Supplement
Authors: Ponphaiboon Juthaporn , Limmatvapirat Sontaya , Limmatvapirat Chutima
Published: August 2024

This study aimed to develop a high-quality dry emulsion incorporating omega-3, 6, and 9 fatty acid-rich ostrich oil for use as a dietary supplement. Extracted from abdominal adipose tissues using a low-temperature wet rendering method, the ostrich oil exhibited antioxidant properties, favorable physicochemical properties, microbial counts, heavy metal levels, and fatty acid compositions, positioning it as a suitable candidate for an oil-in-water emulsion and subsequent formulation as a dry emulsion. Lecithin was employed as the emulsifier due to its safety and health benefits. The resulting emulsion, comprising 10% w/w lecithin and 10% w/w ostrich oil, was stable, with a droplet size of 3.93 ± 0.11 μm. This liquid emulsion underwent transformation into a dry emulsion to preserve the physicochemical stability of ostrich oil, utilizing Avicel® PH-101 or Aerosil® 200 through a granulation process. Although Aerosil® 200 exhibited superior adsorption, Avicel® PH-101 granules surpassed it in releasing the ostrich oil emulsion. Consequently, Avicel® PH-101 was selected as the preferred adsorbent for formulating the ostrich oil dry emulsion. The dry emulsion, encapsulated with a disintegration time of 3.11 ± 0.14 min for ease of swallowing, maintained microbial loads and heavy metal contents within acceptable limits. Presented as granules containing butylated hydroxytoluene, the dry emulsion showcased robust temperature stability, suggesting the potential incorporation of animal fat into dry emulsions as a promising dietary supplement.
Long–Chain Saturated Fatty Acids in Olive Diacylglycerol Stearin Enhances Resistant Starch Content of Candelilla Wax Oleogel Cookies
Authors: Chen Xiaohan , Chen Xiaoxia , Li Daoming , Wang Weifei
Published: August 2024

The purpose of this study was to substitute shortening with olive diacylglycerol oil/candelilla wax (OCW)–olive diacylglycerol stearin (ODS) oleogels and evaluate their impact on starch digestibility in cookies. The in vitro digestibility study confirmed that the OCW/ODS–based cookies exhibited a notable enhancement of 14.6% in slowly digestible starch (SDS) and an increase of 3.14% in resistant starch (RS) values when contrasted with shortening cookies. The XRD pattern indicated that the existence of ODS may improve the formation of complexes between lipids and amylose. The DSC analysis demonstrated that the incorporation of ODS led to a remarkable rise in enthalpy alteration, escalating from 0.90 to 437.70 J/g, suggesting an improved ability to resist gelatinization. The FTIR spectra suggested that the incorporation of ODS might strengthen interactions between the hydrogen bonds and form the short–range ordered structure in OCW/ODS–based cookies. Overall, these results indicated that incorporating OCW/ODS–based oleogels could serve as a feasible substitute for conventional shortening in cookies with decreased starch digestibility.
Integration of Bioinformatics and Machine Learning to Identify CD8+ T Cell-Related Prognostic Signature to Predict Clinical Outcomes and Treatment Response in Breast Cancer Patients
Authors: Wu Baoai , Li Longpeng , Li Longhui , Chen Yinghua , Guan Yue , Zhao Jinfeng
Published: August 2024

The incidence of breast cancer (BC) continues to rise steadily, posing a significant burden on the public health systems of various countries worldwide. As a member of the tumor microenvironment (TME), CD8+ T cells inhibit cancer progression through their protective role. This study aims to investigate the role of CD8+ T cell-related genes (CTRGs) in breast cancer patients. Methods: We assessed the abundance of CD8+ T cells in the TCGA and METABRIC datasets and obtained CTRGs through WGCNA. Subsequently, a prognostic signature (CTR score) was constructed from CTRGs screened by seven machine learning algorithms, and the relationship between the CTR score and TME, immunotherapy, and drug sensitivity was analyzed. Additionally, CTRGs’ expression in different cells within TME was identified through single-cell analysis and spatial transcriptomics. Finally, the expression of CTRGs in clinical tissues was verified via RT-PCR. Results: The CD8+ T cell-related prognostic signature consists of two CTRGs. In the TCGA and METABRIC datasets, the CTR score appeared to be negatively linked to the abundance of CD8+ T cells, and BC patients with higher risk score show a worse prognosis. The low CTR score group exhibits higher immune infiltration levels, closely associated with inhibiting the tumor microenvironment. Compared with the high CTR score group, the low CTR score group shows better responses to chemotherapy and immune checkpoint therapy. Single-cell analysis and spatial transcriptomics reveal the heterogeneity of two CTRGs in different cells. Compared with the adjacent tissues, CD163L1 and KLRB1 mRNA are downregulated in tumor tissues. Conclusions: This study establishes a robust CD8+ T cell-related prognostic signature, providing new insights for predicting the clinical outcomes and treatment responses of breast cancer patients.
Makran Subduction Zone: A Review and Synthesis
Authors: Namdarsehat Peyman , Milczarek Wojciech , Motavalli-Anbaran Seyed-Hani , Khaledzadeh Matin
Published: August 2024

This review synthesizes existing research to elucidate the factors driving the distinct tectonic behaviors in the western and eastern Makran subduction zone, focusing on seismic activity, uplift rate, convergence rate, coupling, and subduction angle. The literature identifies the asymmetry in pressure and the variation in subduction angles between the western and eastern parts of the Makran as key factors in defining the region’s tectonic patterns. The western region has a steeper subduction angle, resulting in lower pressure, reduced coupling, and decreased seismic activity. This disparity arises from different interactions between the subducted and overriding plates. This article offers an overview of the Makran subduction zone, identifies some knowledge gaps, and suggests directions for future research to improve our understanding of this complex geological region. The review highlights the need for more comprehensive GPS stations and targeted studies on subduction dip angles to better understand the region’s tectonic dynamics.