bluuebunny/crossref_metadata_2025 huggingface dataset:
Research on Vehicle Aerodynamics and Thermal Management Based on 1D and 3D Coupling Simulation
Authors: Zhang Yingchao , Jian Jiesong , Wang Guohua , Jia Yuhan , Zhang Jintao
Published: September 2022

In order to ensure the full heat dissipation of heat exchangers, the opening of the grille should be large, which increases the wind drag of the whole vehicle. Most of the research on the grille only focuses on its impact on the heat dissipation of the engine compartment; there is little research on its influence on the performance of the thermal management system, because it is difficult to solve the real-time data interaction of different dimensional models. So we established the 1D and 3D strong coupling model. The biggest difference from other 1D and 3D coupling models is that we can use the interfaces reserved by the two kinds of software to realize real-time data interaction, and simultaneously analyze the 1D thermal management performance and 3D flow field and temperature field of the engine components. The coupling model is used to study three heat balance conditions. The results show that the heat-sinking capability of the cooling system is the worst under the climbing condition; and the refrigeration capacity of the air-conditioning system is the worst under the idling condition. According to the heat balance results and evaluation index priorities, we determine the simulation process. In this article, first the upper grille is gradually closed; then the flow field, temperature field and evaluation indexes are studied through the strong coupling model to obtain the analysis results of the upper grille; then based on the results, the lower grille is gradually closed, and the analysis results of the lower grille are obtained in the same way. The final simulation results show that on the premise of ensuring the performances of engine cooling system and air conditioning refrigeration system, the air drag coefficient is reduced by 17.5 counts compared with the original vehicle.
Determining the Availability of Continuous Systems at Open Pits Applying Fuzzy Logic
Authors: Gomilanovic Miljan , Tanasijevic Milos , Stepanovic Sasa
Published: September 2022

This work presents a model for determining the availability of continuous systems at open pits by applying fuzzy logic and fuzzy inference systems. The applied model was formed by the synthesis of independent partial indicators of availability. The model is based on an expert system for assessing the availability of continuous mining systems. The availability of the system, as a complex state parameter, is decomposed into the partial indicators, reliability, and convenience of maintenance, and the fuzzy compositions, used for integration the partial indicators, are the max–min and min–max compositions. The advantage of this model in comparison to the conventional models is that it takes into account the effect of practical indicators of availability, does not require long-term monitoring, and records necessary to determine the time picture of the system state. This model for determining the availability has a role to help responsible persons at open pits in the planning and control of exploitation, and the adoption of an appropriate maintenance strategy, all with the aim of stable production and cost reduction. The presented model can be used as a tool for the quick assessment of system availability, based on expert judgments and assessments.
Bio-Inspired Optimization Algorithms Applied to the GAPID Control of a Buck Converter
Authors: Itaborahy Filho Marco Antonio , Puchta Erickson , Martins Marcella S. R. , Antonini Alves Thiago , Tadano Yara de Souza , Corrêa Fernanda Cristina , Stevan Sergio Luiz , Siqueira Hugo Valadares , Kaster Mauricio dos Santos
Published: September 2022

Although the proportional integral derivative (PID) is a well-known control technique applied to many applications, it has performance limitations compared to nonlinear controllers. GAPID (Gaussian Adaptive PID) is a non-linear adaptive control technique that achieves considerably better performance by using optimization techniques to determine its nine parameters instead of deterministic methods. GAPID represents a multimodal problem, which opens up the possibility of having several distinct near-optimal solutions, which is a complex task to solve. The objective of this article is to examine the behavior of many optimization algorithms in solving this problem. Then, 10 variations of bio-inspired metaheuristic strategies based on Genetic Algorithms (GA), Differential Evolution (DE), and Particle Swarm Optimization (PSO) are selected to optimize the GAPID control of a Buck DC–DC converter. The computational results reveal that, in general, the variants implemented for PSO and DE presented the highest fitness, ranging from 0.9936 to 0.9947 on average, according to statistical analysis provided by Shapiro–Wilks, Kruskall–Wallis and Dunn–Sidak post-hoc tests, considering 95% of confidence level.
Influencing Factors of Shear Wave Radiation of a Dipole Source in a Fluid-Filled Borehole
Authors: Wang Hao , Wang Caizhi , Liu Yingming , Xia Shouji , Fu Haicheng , Yuan Ye , Bie Kang , Li Xincheng
Published: September 2022

In shear wave far detection logging, dipole-source radiation is the main factor influencing the amplitude of the reflected shear waves. In this paper, a method is derived with the far-field asymptotic solution to calculate the dipole-source radiation of shear waves in a fluid-filled borehole. Then the dipole-source radiation of the shear waves is simulated under both low and high frequencies. In addition, the influences of formation elastic parameters on the dipole-source radiation of the shear waves are analyzed and the variations of the radiation characteristics of the shear wave with source main frequency and borehole radius are compared. Results show that the density and compressional wave velocity of the formation have little effect on the dipole-source radiation of the shear waves. However, the shear wave velocity not only affects the shear wave amplitude radiated to the formation by the dipole source (radiation performance), but also affects the energy distribution of the shear wave at different locations in space (radiation direction). The dipole source has better radiation performance and radiation coverage at low frequency and the optimal excitation frequency in different formations is very close, which is good for the application of this technology under different circumstances. At low frequency, the borehole has little influence on the dipole-source radiation, no matter how large the borehole radius is. However, at high frequency, the borehole modulation of the dipole-source radiation cannot be ignored, especially at large borehole radius.
Different Forms of Solar Energy Progress: The Fast-Growing Eco-Friendly Energy Source in Bangladesh for a Sustainable Future
Authors: Abdullah-Al-Mahbub Md. , Islam Abu Reza Md. Towfiqul , Almohamad Hussein , Al Dughairi Ahmed Abdullah , Al-Mutiry Motrih , Abdo Hazem Ghassan
Published: September 2022

Global fossil fuel reserves are declining due to differential uses, especially for power generation. Everybody can help to do their bit for the environment by using solar energy. Geographically, Bangladesh is a potential zone for harnessing solar energy. In March 2021, the renewable generation capacity in Bangladesh amounted to 722.592 MW, including 67.6% from solar, 31.84% from hydro, and 0.55% from other energy sources, including wind, biogas, and biomass, where 488.662 MW of power originated from over 6 million installed solar power systems. Concurrently, over 42% of rural people still suffer from a lack of electricity, where solar energy can play a vital role. This paper highlights the present status of various forms of solar energy progress in Bangladesh, such as solar parks, solar rooftops, solar irrigation, solar charging stations, solar home systems, solar-powered telecoms, solar street lights, and solar drinking water, which can be viable alternative sources of energy. This review will help decision-makers and investors realize Bangladesh’s up-to-date solar energy scenario and plan better for the development of a sustainable society.
Gender Aspects in Driving Style and Its Impact on Battery Ageing
Authors: Wikner Evelina , Orbay Raik , Fogelström Sara , Thiringer Torbjörn
Published: September 2022

The long and tiring discussion of who are the best drivers, men or women, is not answered in this article. This article, though, sheds some light on the actual differences that can be seen in how men and women drive. In this study, GPS-recorded driving dynamics data from 123 drivers, 48 women and 75 men, are analysed and drivers are categorised as aggressive, normal or gentle. A total of 10% of the drivers was categorised as aggressive, with an even distribution between the genders. For the gentle drivers, 11% of the drivers, the men dominated. The driving style investigation was extended to utilise machine learning, confirming the results from statistical tools. As driving style highly impacts a vehicle’s fuel consumption, while switching over to battery electric vehicles it is important to investigate how the different driving styles impact battery utilisation. Two Li-ion battery cell types were tested utilising the same load cycle with three levels of current amplitude, to represent accelerations for the three drive categories. While one cell type was insensitive to the current amplitude, the highly energy-optimised cell proved to be sensitive to higher current amplitudes, corresponding to a more aggressive driving style. Thus, the amplitude of the dynamic current can for some cells be a factor that needs to be considered for lifetime predictions, while it can be neglected for other cells.
Transient Analysis of a Solar Chimney Power Plant Integrated with a Solid-Sorption Cooling System for Combined Power and Chilled Water Production
Authors: Hassan Hassan Zohair
Published: September 2022

Solar radiation is a reliable energy source that can be used to produce power and cold. Converting solar energy into electricity is attainable through solar chimney power plants. Moreover, solar energy has been utilized to produce cold in adsorption cooling systems. In the adsorption cooling cycle, the adsorption bed releases heat into the environment during the bed cooling phases. This paper introduces a novel hybrid solar chimney power plant integrated with a solar-driven adsorption water chiller. The purpose of the presented system is to enhance the system’s utilization of solar energy by recovering the reactor’s released heat and reusing it to augment the output power. In comparison with conventional solar chimney power plants, the introduced system produces continuous power throughout the day. A mathematical model is developed to evaluate the system’s performance. This model expresses the conservation of energy and mass for every component in the system. The silica gel and water adsorption pair is used in the simulation of the water chiller. It has been found that 62.6% of the adsorption reactor driving heat can be recycled. Therefore, a turbine power increase of 3.22% is obtained with a solar-to-electricity conversion efficiency of 0.4%.
Comparative Study of Thermodynamic Regulation Characteristics in a Dual-Tube Reactor with an External Heat Exchanger
Authors: Bai Yong , Ma Yunfeng , Ke Changjun , Cheng Wang , Guo Guangyan , Zhao Peng , Cao Can , Liao Lifen , Yang Xuebo , Fan Zhongwei
Published: September 2022

A special dual-tube reactor-dual fluidized bed reactor (DFBR), including an external heat exchanger (EHE) and a bypass, was designed to solve the problems that the waste heat of the hot fluid cannot be fully utilized and the reaction temperature cannot be accurately adjusted. Two connection schemes of DFBR and EHE with their thermodynamic equilibrium models and algorithms were proposed, and the optimal scheme was obtained by comparing the outlet temperature and thermal load. The results of the thermodynamic and operating characteristics of the optimal scheme showed that the hot fluid and the cold fluid had positive and negative effects on the heat transfer process, respectively. Increasing the cold fluid mass flow rate in the main stream can enhance the thermal load of the system and increasing the cold fluid mass flow rate in the bypass helped to increase the thermal load of DFBR, even exceeding that of EHE. Adding a bypass can adjust temperature precisely and increasing the inlet temperature can more effectively increase the adjustment range of the reaction zone temperature. The experimental results showed that introducing a bypass can significantly reduce the calculation deviation (12.8%), which decreased with the increasing temperature.
The Multi-Facets of Increasing the Renewable Energy Integration in Power Systems
Authors: Grazioli Giulia , Chlela Sophie , Selosse Sandrine , Maïzi Nadia
Published: September 2022

The increase in the share of renewable energy in the power generation mix plays a pivotal role in the decarbonisation of power systems, thus facilitating the achievement of international and national targets for reducing greenhouse gas emissions and addressing climate change. Due to the intermittent nature of variable renewable energy, the integration of these sources in power systems requires investments in additional solutions and setting strategies to ensure grid stability and reliability. For that purpose, a prospective modelling was applied to the relatively isolated island named Procida, located in the gulf of Naples in Italy, through the bottom-up optimization model TIMES-Procida for a long-term energy plan where technical solutions, i.e., deployment of photovoltaics on rooftops and storage, and policy scenarios, i.e., energy efficiency, were used to analyse the evolution of the energy system. The introduction of renewable energy could be much more relevant when dealing with islands; they appear as decisive territories for experimentation and analysis of the transformation of all power systems. At year 2050, our results address decarbonisation and energy autonomy. They show that only with high shares of renewable energy will the territory see a noticeable decarbonisation of its economic sectors (up to 24%) and a decreasing dependency on imports (−16.6% compared to low renewable integration). By comparing the results of scenarios including or lacking storage solutions, we showcased how this reflected on the investments in PV and on grid congestion relief.
LQG Control of an Open Circuit Axial Piston Pump
Authors: Mitov Alexander , Kralev Jordan , Slavov Tsonyo
Published: September 2022

In recent years, the development of hydraulic variable displacement axial piston machines has been focused in two main directions: improvement of their construction and improvement of their displacement control methods. The goal of both directions is to increase the efficiency of the machines. Increasing their efficiency is key to improving the efficiency of the entire hydraulic system, whether they are used as pumps or hydraulic motors. This motivates the present work, which essentially contains a developed embedded control system designed for a known type of open circuit axial piston pump. The developed solution is implemented on a laboratory test rig. A detailed description of the hydraulic system in the context of pump displacement control is presented, as well as the developed system architecture for its control. The control system is based on a linear-quadratic Gaussian (LQG) controller. The controller is synthesized on the basis of a model obtained by means of identification based on experimental data. The designed controller is validated through experimental studies, enabling the analysis of its performance.
Transformer Leakage Inductance Calculation Method with Experimental Validation for CLLLC Converter Topology
Authors: Yang Zhi , Tahir Mustafa , Hu Sideng , Huang Qiuyan , Zhu Haoqi
Published: September 2022

Leakage inductance is one of the key parameters of a transformer, and it is often intentionally integrated into transformers. Rogowski’s equation is generally used for leakage inductance calculation; however, it is only applicable to concentric winding transformers where windings have the same height. Consequently, it has limited applications. This paper proposes a transformer leakage inductance calculation method using a double Fourier series. The limitation of Rogowski’s leakage inductance equation was analyzed in practical applications, and a new model for calculating the leakage inductance of a double-group-overlapping winding transformer was derived. Experimental prototypes of transformers were developed, and their simulation models were built in Ansys. The correctness of the proposed calculation method for transformer leakage inductance using a double Fourier series was verified by comparing the calculation results with the simulation and measured ones. A sensitivity analysis was also conducted by studying the variations in different parameters that might affect the leakage inductance value. The proposed calculation model gives an intuitive and simple method with less calculation and design effort while maintaining reasonable accuracy for leakage inductance calculation. In addition, the featured double Fourier series approach has a wider range of applications than Rogowski’s equation.
Guidelines for the Implementation of BIM for Post-Occupancy Management of Social Housing in Brazil
Authors: Silva Maria Conceição da Costa , Silva Alyx Diêgo Oliveira , Kohlman Rabbani Emilia Rahnemay , Alencar Luciana H. , Passos Neto George da Mota , Couto João Pedro , Valdes-Vasquez Rodolfo
Published: September 2022

This study presents an analysis of the potential uses of BIM for managing the maintenance and refurbishment of existing housing assets to propose thermal comfort and energy efficiency guidelines for future social housing projects in Brazil. To do so, a case study analysis of a residential development with social–environmental certification in the city of Garanhuns, Pernambuco, Brazil was performed, and a literature review on the use of BIM for residential unit maintenance was conducted. The standard house in the residential development was found to be noncompliant with the Brazilian standard for ventilation openings (NBR 15.220). Therefore, three alternative layouts were created and analyzed to meet the requirements of the standard as well as the needs of the residents. The authors recommend that socio-environmental certifiers use BIM models so that energy performance and other simulations can be carried out. The study also proposes guidelines for BIM implementation in future government housing projects. These guidelines were grouped into five categories: BIM encouragement, energy efficiency, maintenance management, user requirement management, and continuous improvement. The significance of this study is in providing a path for the gradual implementation of BIM for maintenance and post-occupancy management in the Brazilian housing program.
Open-Circuit Voltage Models for Battery Management Systems: A Review
Authors: Pillai Prarthana , Sundaresan Sneha , Kumar Pradeep , Pattipati Krishna R. , Balasingam Balakumar
Published: September 2022

A battery management system (BMS) plays a crucial role to ensure the safety, efficiency, and reliability of a rechargeable Li-ion battery pack. State of charge (SOC) estimation is an important operation within a BMS. Estimated SOC is required in several BMS operations, such as remaining power and mileage estimation, battery capacity estimation, charge termination, and cell balancing. The open-circuit voltage (OCV) look-up-based SOC estimation approach is widely used in battery management systems. For OCV lookup, the OCV–SOC characteristic is empirically measured and parameterized a priori. The literature shows numerous OCV–SOC models and approaches to characterize them and use them in SOC estimation. However, the selection of an OCV–SOC model must consider several factors: (i) Modeling errors due to approximations, age/temperature effects, and cell-to-cell variations; (ii) Likelihood and severity of errors when the OCV–SOC parameters are rounded; (iii) Computing system requirements to store and process OCV parameters; and (iv) The required computational complexity of real-time OCV lookup algorithms. This paper presents a review of existing OCV–SOC models and proposes a systematic approach to select a suitable OCV–SOC for implementation based on various constraints faced by a BMS designer in practical application.
Model Investigations on Electric Discharges over Balloon-Borne Stratospheric VLF Antennas
Authors: Miś Tomasz Aleksander , Modelski Józef , Ciuba Maciej
Published: September 2022

Long linear antennas for very low frequency radio transmissions, supported by aerostats, unanchored, and raised to high altitudes, present themselves as slow-moving, highly conductive disturbances in cloud layers, acquiring an electrical charge and being subjected to intense coronae. High electric field strength values around those objects increase the risk of lightning strikes, which could be disastrous to the mechanical structures of the balloon mission (both the antenna and the balloon) and the radio transmitter. This paper aims to investigate the inception of lightning strikes over two essential elements of such missions: a talc-covered latex (balloon material) and the model of the linear antenna, made of different materials. Based on the high-voltage experiments with the recorded electrical discharges, the properties, functions, and possible ameliorations of the talc cover are presented, as well as the basic characteristics of lightning forms around the very long antenna system, with a proposition of design requirements and constraints reflecting the safety of the balloon missions employing a VLF antenna from lightning strikes.
Study on Surrounding Rock Control and Support Stability of Ultra-Large Height Mining Face
Authors: Wang Sheng , Li Xuelong , Qin Qizhi
Published: September 2022

Surrounding rock control and support stability in the process of coal seam mining in ultra-large height mining face are the key to normal mine operation. In this study, the roof movement and deformation of an ultra-large height mining face are analyzed, and the working resistance of the ultra-large height mining face is obtained by introducing the equivalent immediate roof. By analyzing the coal wall spalling, the multiple positions of the spalling and the required support force of the support are obtained. At the same time, ultra-large height supports are more prone to instability problems. In this study, the stability of the ultra-large height supports was analyzed by establishing a mechanical model. The results show that: 1. The overturning limit angle of support has a hyperbolic relationship with the center of gravity. 2. Under the condition of ultra-large height, the increase in the base width of the bracket significantly improves the stability of the supports. 3. The sliding limit angle of support is positively correlated with the support load and the friction coefficient between the support and the floor. The above conclusions can provide guidance on the selection of supports and the adoption of measures to enhance the stability of the supports during use under ultra-large height conditions. The working resistance of the ultra-large height supports in the 108 mining face of the Jinjitan Coal Mine was monitored. The monitoring results show that: The average resistance of the supports is 22.6 MPa. The selected supports can meet the stability requirements of the working face support. The frequency of mining resistance in 0~5 MPa accounts for 28.38%, which indicates that some supports are insufficient for the initial support force during the moving process. Furthermore, the stability of the supports can be enhanced by adjusting the moving process. This study provides a reference for the selection of supports in ultra-large height mining faces and proposes measures to enhance the stability of the supports, which provides guidance for the safe mining of coal in ultra-large height mining faces.
Energy Use of Woody Biomass in Poland: Its Resources and Harvesting Form
Authors: Wieruszewski Marek , Górna Aleksandra , Stanula Zygmunt , Adamowicz Krzysztof
Published: September 2022

Currently, woodchips and logging residues form the greatest share of biomass fuels used to generate heat in combined heat and power plants. They are supplied from various regions of the EU. The calorific values of the wood species used as biomass may vary significantly depending on the moisture and composition of the fuel, harvest seasonality, location, and other factors. This article presents the main resources of forest biomass and its characteristic features, as well as the calorific value of woodchips depending on the moisture content. Our research is based on the source data of forest resources from the State Forests National Forest Holding (PGLLP) in Poland. The research conducted by the main forestry enterprise in Poland covered a period of four years. The data on the harvesting of woodchips and logging residues converted into the calorific values of biomass were based on our research and a review of reference publications. Standard methods were used in the research, which included an analysis of the species and assortment structure of the forest biomass of energetic significance that was available for use. The research showed that the moisture content of the woodchips and lump wood was about 30%. The average annual energy value of the wood in the total area of forest resources was 0.07 GJ/ha, whereas the highest value was 0.14 GJ/ha. Between 2018 and 2021, the average energy resources of forest biomass in Poland increased from 351.8 TJ to 498.4 TJ.
Optimization of DC, AC, and Hybrid AC/DC Microgrid-Based IoT Systems: A Review
Authors: Aljafari Belqasem , Vasantharaj Subramanian , Indragandhi Vairavasundaram , Vaibhav Rhanganath
Published: September 2022

Smart microgrids, as the foundations of the future smart grid, combine distinct Internet of Things (IoT) designs and technologies for applications that are designed to create, regulate, monitor, and protect the microgrid (MG), particularly as the IoT develops and evolves on a daily basis. A smart MG is a small grid that may operate individually or in tandem with the electric grid, and it is ideal for institutional, commercial, and industrial consumers, as well as urban and rural societies. A MG can operate in two methods (stand-alone and grid-connected), with the ability to transition between modes due to local grid faults, planned maintenance, expansions, deficits and failures in the host system, and other factors. Energy storage is the process of storing and converting energy that can be used for a variety of purposes, including voltage and frequency management, power backup, and cost optimization. IoT is designed to deliver solutions for optimal energy management, security protocols, control methods, and applications in the MG, with numerous distributed energy resources (DER) and interconnected loads. The use of IoT architecture for MG operations and controls is discussed in this research. With the use of power grid equipment and IoT-enabled technology, MGs are enabling local networks to give additional services on top of the essential supply of electricity to local networks that operate simultaneously or independently from the regional grid. Additionally, this review shows how hybrid AC/DC MGs are advantageous compared to AC and DC MGs. The state-of-the-art optimization techniques and trends in hybrid MG research are included in this work.
A Review on Reliability of Integrated Electricity-Gas System
Authors: Zhou You , He Chuan
Published: September 2022

With the development of society and the increase in energy demand, the electric power system and natural gas system become larger and larger, where the network is increasingly complex. The continuous and stable supply of energy is also important. The reliability evaluation of the power system and natural gas system is an essential part of maintaining efficient operation of the system. In this paper, the concept of the integrated electricity-gas system is introduced first, and then the importance of the reliability evaluation of the power system and natural gas system is emphasized. In addition, the main reliability indices and reliability evaluation method of the two systems are presented, and some practical examples are given. Finally, conclusions on the reliability evaluation of the integrated electricity-gas system are drawn.
Rate-Based Modeling and Assessment of an Amine-Based Acid Gas Removal Process through a Comprehensive Solvent Selection Procedure
Authors: Agarwal Neha , Cao Nhien Le , Lee Moonyong
Published: September 2022

In this study, an industrial acid gas removal (AGR) process which uses amine-based solvents was designed and simulated. The selection of suitable absorbents is crucial for an effective AGR process. Therefore, various single and blended amine-based solvents for capturing acid gases were evaluated through a comprehensive procedure, including solvent screening and process design steps. First, various solvents were screened for their CO2 and H2S absorption efficiencies. Promising solvents were then selected for the process design step, in which all process alternatives were simulated and rigorously designed using Aspen Plus. The non-equilibrium rate-based method with an electrolyte non-random two-liquid thermodynamic model was employed for modeling the absorption column. All processes were evaluated in terms of energy requirements, costs, and carbon emissions. The results show that a blend of methyldiethanolamine and piperazine solutions are the most promising solvents for the AGR process, as they can save up to 29.1% and 30.3% of the total annual costs and carbon emissions, respectively, compared to the methyldiethanolamine + diethanolamine solvent process.
On the Monotonicity and Positivity of Physics-Informed Neural Networks for Highly Anisotropic Diffusion Equations
Authors: Zhang Wenjuan , Al Kobaisi Mohammed
Published: September 2022

Physics-informed neural network (PINN) models are developed in this work for solving highly anisotropic diffusion equations. Compared to traditional numerical discretization schemes such as the finite volume method and finite element method, PINN models are meshless and, therefore, have the advantage of imposing no constraint on the orientations of the diffusion tensors or the grid orthogonality conditions. To impose solution positivity, we tested PINN models with positivity-preserving activation functions for the last layer and found that the accuracy of the corresponding PINN solutions is quite poor compared to the vanilla PINN model. Therefore, to improve the monotonicity properties of PINN models, we propose a new loss function that incorporates additional terms which penalize negative solutions, in addition to the usual partial differential equation (PDE) residuals and boundary mismatch. Various numerical experiments show that the PINN models can accurately capture the tensorial effect of the diffusion tensor, and the PINN model utilizing the new loss function can reduce the degree of violations of monotonicity and improve the accuracy of solutions compared to the vanilla PINN model, while the computational expenses remain comparable. Moreover, we further developed PINN models that are composed of multiple neural networks to deal with discontinuous diffusion tensors. Pressure and flux continuity conditions on the discontinuity line are used to stitch the multiple networks into a single model by adding another loss term in the loss function. The resulting PINN models were shown to successfully solve the diffusion equation when the principal directions of the diffusion tensor change abruptly across the discontinuity line. The results demonstrate that the PINN models represent an attractive option for solving difficult anisotropic diffusion problems compared to traditional numerical discretization methods.
Neural Network Controlled Solar PV Battery Powered Unified Power Quality Conditioner for Grid Connected Operation
Authors: Okwako Okech Emmanuel , Lin Zhang-Hui , Xin Mali , Premkumar Kamaraj , Rodgers Alukaka James
Published: September 2022

The Unified Power Quality Conditioner (UPQC) is a technology that has successfully addressed power quality issues. In this paper, a photovoltaic system with battery storage powered Unified Power Quality Conditioner is presented. Total harmonic distortion of the grid current during extreme voltage sag and swell conditions is more than 5% when UPQC is controlled with synchronous reference frame theory (SRF) and instantaneous reactive power theory (PQ) control. The shunt active filter of the UPQC is controlled by the artificial neural network to overcome the above problem. The proposed artificial neural network controller helps to simplify the control complexity and mitigate power quality issues effectively. This study aims to use a neural network to control a shunt active filter of the UPQC to maximise the supply of active power loads and grid and also used to mitigate the harmonic problem due to non-linear loads in the grid. The performance of the model is tested under various case scenarios, including non-linear load conditions, unbalanced load conditions, and voltage sag and voltage swell conditions. The simulations were performed in MATLAB/Simulink software. The results showed excellent performance of the proposed approach and were compared with PQ and SRF control. The percent total harmonic distortion (%THD) of the grid current was measured and discussed for all cases. The results show that the %THD is within the acceptable limits of IEEE-519 (less than 5%) in all test case scenarios by the proposed controller.
Evaluation of OKRA (Abelmoschus esculentus) Macromolecular Solution for Enhanced Oil Recovery in Kazakhstan Carbonate Reservoir
Authors: Abbas Azza Hashim , Ajunwa Obinna Markraphael , Mazhit Birzhan , Martyushev Dmitriy A. , Bou-Hamdan Kamel Fahmi , Alsaheb Ramzi A. Abd
Published: September 2022

Natural polymers have been investigated as part of the endeavors of green chemistry practice in the oil field. However, natural polymer studies are still preliminary. The current study examines okra’s (natural polymer) efficiency for polymer flooding, particularly in Kazakhstan. The evaluation targets the heavy oil trapped in carbonate reservoirs. SEM and FTIR were used to characterize morphology and chemical composition. A rheology study was conducted under different shear rates for three plausible concentrations: 1 wt.%, 2 wt.% and 5 wt.%. The core flooding was challenged by the low porosity and permeability of the core. The results showed that okra’s size is between 150–900 μm. The morphology can be described by rod-like structures with pores and staking as sheet structures. The FTIR confirmed that the solution contains a substantial amount of polysaccharides. During the rheology test, okra showed a proportional relationship between the concentration and viscosity increase, and an inversely proportional relationship with the shear rate. At reservoir temperature, the viscosity reduction was insignificant, which indicated good polymer stability. Okra showed shear-thinning behavior. It was fitted to the Ostwald–de Waele power-law model by a (90–99)% regression coefficient. The findings confirm okra’s pseudo-plasticity, and that it is proportional to the solution concentration. The incremental oil recovery was 7%. The flow was found to be restricted due to the mechanical entrapment resulting from the large molecule size and the low porosity–permeability of the system. This study proves that the dominating feature of natural polysaccharide derivatives is their applicability to moderate reservoir conditions. The current study is a positive attempt at natural polymer application in Kazakhstan and similar field conditions.
Cheese Whey as a Potential Feedstock for Producing Renewable Biofuels: A Review
Authors: Osorio-González Carlos S. , Gómez-Falcon Natali , Brar Satinder K. , Ramírez Antonio Avalos
Published: September 2022

Agro-industrial residues such as bagasse, pomace, municipal residues, vinasse and cheese whey are an environmental problem around the world, mainly due to the huge volumes that are generated because of the food production to satisfy the nutritional needs of the growing world population. Among the above residues, cheese whey has gained special attention because of its high production with a worldwide production of 160 million tons per year. Most of it is discarded in water bodies and land causing damage to the environment due to the high biological oxygen demand caused by its organic matter load. The environmental regulations in developing countries have motivated the development of new processes to treat transform cheese whey into added-value products such as food supplements, cattle feed and food additives. In addition, during the last decade, several processes and technologies have been developed to produce bioenergy through the biotechnological process using cheese whey as a potential feedstock. This review discusses the production of bioethanol, biohydrogen, biomethane and microbial lipid-biodiesel production using cheese whey as a potential substrate.
Valorization of Dairy By-Products: Efficiency of Energy Production from Biogas Obtained in Anaerobic Digestion of Ultrafiltration Permeates
Authors: Tarapata Justyna , Zieliński Marcin , Zulewska Justyna
Published: September 2022

This study aimed at evaluating the methane potential of two ultrafiltration (UFP) and two diafiltration (DFP) permeates generated during milk protein concentration. The permeates were characterized by a different chemical oxygen demand (COD) ranging from 7610 mg O2/L to 57,020 mg O2/L. The CH4 production efficiency was recorded for 20 days and ranged from 149 to 181 NL/kg CODadded. Moreover, the possibilities of the use of UFP/DFP to produce electricity and heat with a combined heat and power (CHP) unit was analyzed to underline the impact of the implementation of anaerobic digestion on the electric and thermal energy requirements of a dairy plant. It was concluded that the application of anaerobic digestion to UFP and DFP treatments generates the energy required to cover all the large-scale dairy plant energy demands and produce extra income. The amount of permeates generated annually in the analyzed dairy plant will enable the production of approx. 22,699 MWh of electricity and 85,516 GJ of heat. This would require a biogas plant with a 3 MW yield. Additionally, the lactose production from UFP/DFP was considered as an alternative or parallel solution for its management. The study confirmed that the biogas and lactose production from UFP/DFP enables plant owners to adjust a plant’s management towards one of these two solutions.
Effects of Pine Plantation on Native Ecuadorian Páramo Vegetation
Authors: Medina-Torres Byron , Jonard Mathieu , Rendón Melina , Jacquemart Anne-Laure
Published: September 2022

Exotic pine plantations, installed mainly for timber production and carbon sequestration purposes, cover an ever-expanding area of equatorial and tropical regions; however, their economic and environmental benefits are under debate due to their potential negative effects on native plant species conservation. The native understory plant species richness and cover under pine (Pinus radiata D. Don) plantations were compared with natural grasslands in the Ecuadorian Páramo. We analyzed the vegetation in four zones: Antisana (8-year-old pines), Cajas (16-year-old pines), Tisaleo (41-year-old pines) and Cotopaxi (53-year-old pines). The total understory plant cover decreased between 29% and 90% under pine plantations in all zones. The mean species richness in the pine plantations decreased by 44% in Antisana, Cajas and Tisaleo but not in Cotopaxi. Pine plantations strongly reduced the abundance of herbaceous light-demanding species (59%), except small herbs whose cover increased under pine (17.6%). Shrub cover was also negatively affected in Tisaleo and Cotopaxi (7.4%). Pine afforestation effects on Páramo vegetation depend mainly on canopy cover which changes with age and growing conditions (altitude) and secondarily on the vegetation state at the time of planting, resulting from land use history and ecological conditions. The pine effect was therefore more pronounced in the young and dense plantations of Antisana and Cajas than in the old and open stand of Cotopaxi, whose understory vegetation was more similar to that of grasslands.
Mid-Term Natural Regeneration of Pinus halepensis Mill. after Post-Fire Treatments in South-Eastern Spain
Authors: Navidi Mehdi , Lucas-Borja Manuel Esteban , Plaza-Álvarez Pedro Antonio , Carra Bruno Gianmarco , Parhizkar Misagh , Antonio Zema Demetrio
Published: September 2022

Straw mulching and salvage logging are common management techniques after forest wildfires. However, these post-fire actions may result in an additional disturbance in burned soils, which may hamper the natural regeneration of forest species, especially in Mediterranean areas. The results of the investigations on the impacts of these post-fire management techniques are still insufficient, and especially about post-fire regeneration of Pinus halepensis Mill. This tree species is typical of the western Mediterranean Basin and is hardly threatened by forest wildfires. To fill these literature gaps, this study explores the effects of salvage logging after straw mulching on the regeneration of Pinus halepensis Mill. throughout four years after a wildfire. These effects have been also related to the changes in the main chemical properties of the supporting soils. Compared to the burned but non-treated areas, after four years of fire and post-fire treatments, we found that: (i) mulched and non-logged sites showed a significantly higher number of seedlings (+66%) with larger diameter (+12%) and higher height (+25%); (ii) logging did not significantly increase this number (+74%), but, in mulched and logged sites, the seedlings had significantly lower diameters (−18%) and heights (−9%); (iii) an increase in the seedling number (+29%), and decreases in the plant diameter (−34%) and height (−15%) were observed in the non-mulched and logged areas; (iv) no significant differences in the other morphometric parameters of seedlings were detected among all post-fire treatments; (v) a clear gradient between the organic matter content of soils and the number of plants growing under the four treatments was evident. These results support the task of forest managers in accelerating the recovery of natural vegetation in burned pine forests in the Mediterranean environment.
Applying the “Goldilocks Rule” to Riparian Buffer Widths for Forested Headwater Streams across the Contiguous U.S.—How Much Is “Just Right”?
Authors: Jayasuriya Maneesha T. , Germain René H. , Stella John C.
Published: September 2022

Delineating riparian management zones (RMZ) around streams to protect riparian ecological functions is critical during forest management. This study compared the area dedicated to RMZ using the USFS functional-based riparian buffer approach versus individual state-defined riparian buffer allocation strategies along headwater streams across 17 states within the US. The USFS method uses a variable-width riparian buffer that seeks to capture the functions of a riparian area. Our study sought to contrast this USFS method with various state-defined RMZ guidelines. The functional approach delineated the highest percentages of the watershed area around headwater streams in most watersheds, sometimes >20% of forestland, whereas state RMZ guidelines delineated <10% of forestland around headwater streams in many watersheds. Although many state guidelines failed to identify the variable widths of functional riparian areas, some watersheds in the Great Lakes states over-allocated forestland as riparian when compared to a functional riparian delineation. The topographic and forest composition differences observed across the study area were not represented by their respective state RMZ guidelines, and these variables strongly influence the delineation of a functional RMZ.
Soil Quality Assessment and Management in Karst Rocky Desertification Ecosystem of Southwest China
Authors: Wu Qian , Zheng Wei , Rao Chengjiao , Wang Enwen , Yan Wende
Published: September 2022

Karst rocky desertification is a common phenomenon in terrestrial ecosystems, and the deterioration of soil quality has a serious side effect on the aboveground vegetation and underground environmental factors. To clarify the variety of soil quality in different rocky desertification grades in typical karst areas of southwest China, the soil quality of four rocky desertification grades was calculated by a single model (SQI: soil quality index), two screening processes (TDS: total dataset and MDS: minimum dataset) and three scoring methods (SSF: standard scoring function, SL: linear scoring function and SNL: nonlinear scoring function). The key results are as follows: Significant differences were found in the soil environment factors in non-rocky desertification (NRD), light rocky desertification (LRD) and moderate rocky desertification (MRD) as compared to intense rocky desertification (IRD) (p < 0.01). Except for total potassium (TK), manganese (Mn) and amylase, the other soil environmental factors showed U-shaped changes. In contrast, TK, Mn and amylase increased first and then decreased. Additionally, the SQI based on MDS in SSF, SL and SNL was IRD (0.58) > NRD (0.48) > LRD (0.45) > MRD (0.43), IRD (0.53) > NRD (0.42) > LRD (0.39) > MRD (0.36) and IRD (0.57) > NRD (0.47) > MRD (0.42) > LRD (0.40), respectively. However, the SQI was always in the trend of IRD > NRD > MRD > LRD based on the TDS. Overall, although the soil area is scarce, the edaphic properties, enzyme activities and soil quality are not poor in the IRD. Furthermore, we found that SNL was more suitable for the evaluation of soil quality in the karst rocky desertification area (R2 = 0.63, p < 0.001 and the coefficient of variation = 30.69%). This research helps to clarify the variation in soil properties and quality during the succession of rocky desertification and provides guidelines for the sustainable management of soil quality in areas of southwest China.
A Unique Grubbing Head Prototype for Environmentally Friendly and Sustainable Stump Removal
Authors: Staněk Luboš , Zvěřina Ladislav , Ulrich Radomír , Pavlíková Eva Abramuszkinová
Published: September 2022

Stumps left behind after the felling of trees represent an important source of renewable energy that could be used for fuel mixtures as a sustainable solution. The subject of this research was to determine the influence of tree species, stump diameter size, and subsoil on the time required for stump processing. Evaluated parameters included the mean time for one stump’s processing; the stump processing time based on the stump diameter; different soil types and tree species; and the tree species type (coniferous, broadleaved). The research was conducted in the territory of the Czech Republic in 2020/2021. There were 287 stumps and 6 tree species in total. The stumps were uprooted using a new prototype of grubbing head, developed at Mendel University in Brno, attached as an adapter on the boom of a JCB JS 220 LC excavator with a tracked undercarriage and was controlled remotely from an excavator cab. Research results confirmed that the processing time of one stump depends on the stump diameter (GLM), and the time needed for the processing of one stump increased with an increase in stump diameter in all experimental sites. An equation was suggested to predict the time needed to work on one stump.