bluuebunny/crossref_metadata_2025 huggingface dataset:
Air Cavity Building Walls: A Discussion on the Opportunity of Filling Insulation to Support Energy Performance Improvement Strategies
Authors: Magrini Anna , Marenco Ludovica , Leoni Valentina , Gamba Roberta
Published: November 2022

The paper intends to discuss the use of cavity wall insulation in existing buildings for energy improvement. Cavity walls are widely spread throughout the EU, typically in buildings from the 20th century, which are recognized as the subject of urgent and deep energy renovation interventions. Their main characteristic is an empty air cavity between two layers of building materials (typically brick, stone, or concrete). Filling the empty air cavity with insulating materials reduces energy loss by transmission through opaque envelope surfaces, and therefore, it represents a cheap solution to obtain a significant reduction in building energy consumption. Various aspects should be carefully evaluated for the effectiveness of this type of intervention: The first step is knowing the materials’ behavior depending on their thermal and hygrometric parameters (conductivity and transmittance, thermal bridge transmittance, vapor permeability, and resistance to vapor diffusion). Some indications on limits or reference/target values are usually given by national/regional laws and EU Directives. The filling insulation could lead to collateral problems (thermal bridges, risk of vapor condensation inside walls, etc.). To help understand the relevance and the impact of this insulation technique, an example of the assessments of a common cavity wall type is presented. The analyses highlight the usefulness of an organized and systematic database on building envelope features to set targeted energy-saving actions. Public administrations could base their strategies on this information to promote the reduction of energy consumption on a large scale with efficient and economically sustainable interventions. In the absence of more specific databases, the Energy Performance Certificates (EPC) data consulting could help develop thermal insulation strategies at a regional/national level. In particular, the diffusion of cavity walls can be obtained as a function of wall surface and cavity thickness for estimating the energy saving potential, economic impact, and general feasibility of systematic insulation-filling actions. An example of this kind of database analysis is discussed and carried out on a regional scale to explain how it could represent a useful approach to evaluate potential energy-saving interventions. The sample building stock provides suggestions on the possibility to extend the considerations on a larger scale to help set systematic energy-saving strategies.
Prediction of Remaining Useful Life of Lithium Batteries Based on WOA-VMD and LSTM
Authors: Ouyang Mingsan , Shen Peicheng
Published: November 2022

The remaining useful life (RUL) of a lithium-ion battery is directly related to the safety and reliability of the electric system powered by a lithium-ion battery. Accurate prediction of RUL can ensure timely replacement and maintenance of the batteries of the power supply system, and avoid potential safety hazards in the lithium-ion battery power supply system. In order to solve the problem that the prediction accuracy of the RUL of lithium-ion batteries is reduced due to the local capacity recovery phenomenon in the process of the capacity degradation of lithium-ion batteries, a prediction model based on the combination of the whale optimization algorithm (WOA)-variational mode decomposition (VMD) and short-term memory neural network (LSTM) was proposed. First, WOA was used to optimize the VMD parameters, so that the WOA-VMD could fully decompose the capacity signal of the lithium-ion battery and separate the dual component with global attenuation trend and a series of fluctuating components representing the capacity recovery from the capacity signal of the lithium-ion battery. Then, LSTML was used to predict the dual component and fluctuation components, so that LSTM could avoid the interference of the capacity recovery to the prediction. Finally, the RUL prediction results were obtained by stacking and reconstructing the component prediction results. The experimental results show that WOA-VMD-LSTM can effectively improve the prediction accuracy of the RUL of lithium-ion batteries. The average cycle error was one cycle, the average RMSE was less than 0.69%, and the average MAPE was less than 0.43%.
Experimental Results for an Off-Road Vehicle Powered by a Modular Fuel Cell Systems Using an Innovative Startup Sequence
Authors: Raceanu Mircea , Bizon Nicu , Varlam Mihai
Published: November 2022

This article deals with implementing a rule-based control method and startup sequence of a hybrid electric vehicle powered by a modular fuel cell system as its primary energy source and a lithium-ion battery system as its secondary energy source. The modular fuel cell system is composed of two separate fuel cell systems, electrically coupled to a one-power converter, using a programmable device. Depending on the vehicle’s operating mode, either both systems are used or just one of them. The vehicle’s fuel efficiency is improved by operating at constant power in the peak efficiency range of each fuel cell system. The experimental results show that the proposed system can significantly improve the fuel economy of a fuel cell vehicle and extend the driving range, while avoiding start/stop cycles. Additionally, this solution can increase the fuel cells’ lifecycle.
Structural Performance of Additively Manufactured Cylinder Liner—A Numerical Study
Authors: Alshwawra Ahmad , Abo Swerih Ahmad , Sakhrieh Ahmad , Dinkelacker Friedrich
Published: November 2022

Climate change is exacerbated by vehicle emissions. Furthermore, vehicle pollution contributes to respiratory and cardiopulmonary diseases, as well as lung cancer. This requires a drastic reduction in global greenhouse gas emissions for the automobile industry. To address this issue, researchers are required to reduce friction, which is one of the most important aspects of improving the efficiency of internal combustion engines. One of the most important parts of an engine that contributes to friction is the piston ring cylinder liner (PRCL) coupling. Controlling the linear deformation enhances the performance of the engine and, as a result, contributes positively to its performance. The majority of the tests to study the conformability between cylinder liner and piston were carried out on cylinder liners made of cast iron. It is possible to improve the performance of piston ring cylinder liner couplings by implementing new and advanced manufacturing techniques. In this work, a validated finite element model was used to simulate the performance when advanced manufactured materials were adapted. The deformation of the cylinder liner due to thermal and mechanical loads is simulated with five different additive manufactured materials (Inconel 625, Inconel 718, 17-4PH stainless steel, AlSi10Mg, Ti6Al4V). Simulated roundness and straightness errors, as well as maximum deformation, are compared with conventional grey cast iron liner deformation. Some additive manufactured materials, especially Ti6Al4V, show a significant reduction in deformation compared to grey cast iron, both in bore and circumferential deformation. Results show that Ti6Al4V can reduce maximum liner deformation by 36%. In addition, the roundness improved by 36%. The straightness error when Ti6Al4V was used also improved by 44% on one side, with an average of 20% over the four sides. Numerical results indicate that additive manufactured materials have the potential to reduce friction within the piston liner arrangement of internal combustion engines.
General Modelling Method for the Active Distribution Network with Multiple Types of Renewable Distributed Generations
Authors: Chen Haidong , Pan Xueping , Sun Xiaorong , Cheng Xiaomei
Published: November 2022

With a proliferation of diverse types of renewable distributed generation (DG) into the distribution network, an equivalent model of an active distribution network (ADN) is extremely important, since the detailed modeling of the whole ADN is much more complex and time consuming. However, different studies developed different model structures of ADNs, which are difficult to be applied in a power system simulation. At the same time, the DG’s low voltage ride through the (LVRT) control was not considered in the existing ADN model, which may lead to a large modelling error. In this paper, a general equivalent model is developed for the ADN with a significant amount of DGs, based on a two-step modelling method. Step one, motivated by the dynamic similarities between the doubly-fed induction generator (DFIG)-based wind turbines, direct drive permanent magnet synchronous generator (DDPMSG)-based wind turbines, and photovoltaic (PV) generation, a general model structure of a renewable DG is initially developed. Then, an aggregation method for the DG’s nonlinear subsystems of the low voltage ride through (LVRT) control and the converter’s current limits are presented. Step two, the ADN model is represented by a general renewable DG model paralleled with a composite load model, and the model is validated, based on an actual distribution network with different renewable DG penetrations and different disturbance degrees. The simulation results show that our model outperforms others with acceptable errors.
Polyhydroxybutyrate-Natural Fiber Reinforcement Biocomposite Production and Their Biological Recyclability through Anaerobic Digestion
Authors: Vu Danh H. , Mahboubi Amir , Ferreira Jorge A. , Taherzadeh Mohammad J. , Åkesson Dan
Published: November 2022

The existing recycling methods of PHA-based material are ineffective in terms of increasing resource efficiency and the production of high value end-of-life products. Therefore, in this study, a novel approach of acidogenic fermentation was proposed to recycle PHB-based composites reinforced with natural fibers such as cellulose, chitin, chitosan, orange waste, sawdust, soy protein, and starch. The inclusion of cellulose, chitosan, and sawdust improved the impact properties of the composites while other fillers had various effects on the mechanical properties. These three composites and neat PHB were subsequently subjected to biological degradation via acidogenic digestion to determine the possibility of converting PHB-based composites into volatile fatty acids (VFAs). Two different pH levels of 6 and 10 were applied to assess the effect of pH on the bioconversion and inhibition of the methanogenesis. The results showed promising PHB degradation, contributing to considerable VFA production of 2.5 g/L at pH 6 after 47 days. At pH 6, the presence of the natural fibers in the biocomposites promoted the degradation rate. On the contrary, pH 10 proved to be more suitable for the degradation of the fibers. The VFA which is produced can be recirculated into PHB production, fitting with the concept of a circulating bioeconomy.
Evolution of Turbine Cooled Vanes and Blades Applied for Large Industrial Gas Turbines and Its Trend toward Carbon Neutrality
Authors: Takeishi Kenichiro
Published: November 2022

Photovoltaics and wind power are expected to account for a large share of power generation in the carbon-neutral era. A gas turbine combined cycle (GTCC) with an industrial gas turbine as the main engine has the ability to rapidly start up and can follow up to load fluctuations to smooth out fluctuations in power generation from renewable energy sources. Simultaneously, the system must be more efficient than today’s state-of-the-art GTCCs because it will use either Carbon dioxide Capture and Storage (CCS) when burning natural gas or hydrogen/ammonia as fuel, which is more expensive than natural gas. This paper describes the trend of cooled turbine rotor blades used in large industrial gas turbines that are carbon neutral. First, the evolution of cooled turbine stationary vanes and rotor blades is traced. Then, the current status of heat transfer technology, blade material technology, and thermal barrier coating technology that will lead to the realization of future ultra-high-temperature industrial gas turbines is surveyed. Based on these technologies, this paper introduces turbine vane and blade cooling technologies applicable to ultra-high-temperature industrial gas turbines for GTCC in the carbon-neutral era.
Renewable Energy Communities as Modes of Collective Prosumership: A Multi-Disciplinary Assessment Part II—Case Study
Authors: Chaudhry Shubhra , Surmann Arne , Kühnbach Matthias , Pierie Frank
Published: November 2022

Renewable Energy Communities (RECs) have been defined as modes of collective prosumership under the Renewable Energy Directive (RED II). We evaluate the benefits offered by RECs and the barriers and enablers impacting their uptake. Germany is taken as a case study for a novel multi-disciplinary assessment of a potential REC intended as a climate-neutral, mixed-use district. We found that energy cooperatives may not be suited to form RECs, but the future may see an uptake of innovative organizational structures such as the Consumer Stock Ownership Plan. It has been shown that a high degree of prosumership can provide technical and economic benefits with maximum greenhouse gas savings of 35% and a maximum self-consumption share of 61% compared to no prosumership. The REC has a negative Net Present Value (NPV) after 25 years of operation and lacks financial attractiveness. A positive NPV is only possible by using the cost savings from prosumership to recoup the investments faster. RECs are a promising mode of citizen participation in the energy transition; however, for their application in Germany, together with the currently missing regulatory allowance of sharing energy between small-scale parties over a public grid, dedicated subsidies, one-time grants or price support for operators are needed.
Energy Management for an Air Conditioning System Using a Storage Device to Reduce the On-Peak Power Consumption
Authors: Tipasri Wunvisa , Suksri Amnart , Velmurugan Karthikeyan , Wongwuttanasatian Tanakorn
Published: November 2022

To reduce the on-peak electrical power consumption, storage devices are widely performed with the help of an energy management system. According to IEA, residential air conditioning consumes 70% of the electricity, increasing by 4% every year. To minimize peak power consumption, thermal energy storage (TES) can be used to store cooled water for the air conditioning system. An efficient chilled water tank was designed and computationally investigated. Three-dimensional cylindrical tanks were simulated with seven different heights to diameter (H:D) ratios. At first, the temperature changes in a chilled water tank during discharging and charging periods were studied. An 11-h charging period was carried out during the off-peak time at night, while the discharging period was 13 h during the daytime. Under time constraints regarding peak and off-peak periods, a tank with an H:D = 2.0 can only be used for 13-h discharging. Then the chilled water was simulated with a set temperature of 4 °C during the charging. This resulted in the system being usable for six days, after which it had to be stopped for longer charging. A storage tank with an H:D ratio of 2.0 was found to be suitable for an air conditioning system. If six days of operations (one day off) were used, it could save 15.38% of electrical energy consumption and 51.65% of electricity cost. This saving leads to a 5.55-year payback period.
The Development of Coal Mine Methane Utilization Infrastructure within the Framework of the Concept “Coal-Energy-Information”
Authors: Smirnova Arina , Varnavskiy Kirill , Nepsha Fedor , Kostomarov Roman , Chen Shaojie
Published: November 2022

The operation of coal mines is intricately linked with emitting a large quantity of coal mine methane, and in most cases, this methane releases into the atmosphere. In total, according to statistics, coal mining enterprises emit 8% of anthropogenic methane, determining a contribution to greenhouse gas emissions to the amount of 17%. There are various means for coal mine methane utilization. In this study, the concept “Coal-Energy-Information” is proposed. This concept implies both the construction of data processing centers on the industrial sites of coal mines and the usage of coal mine methane. Coal mine methane can be used as a primary energy source for the energy supply of data processing center consumers as well as coal mine consumers with necessary energy resources (electricity, heat, and cooling). Within the framework of the proposed concept, three options of coal mine methane utilization are considered. The first option is the use of gas genset for electrical and thermal energy generation (cogeneration) and their usage for coal mine and constructed data processing centers and consumers’ power supply. The second option is absorption refrigerator usage (with coal mine methane direct burning) for cooling the IT equipment of constructed data processing centers. The last one is the use of a gas genset and absorption refrigerator (trigeneration) for constructed data processing centers’ and coal mine consumers’ energy supplies (electricity, heat, and cooling). In conclusion, it is noted that proposed concept is closely correlated with the program for the development of the coal industry in Russia for the period up to 2035, since it allows creating a base for the implementation of innovative technologies based on digital platforms that ensure the development of coal mining technology without the constant presence of personnel in underground mining facilities.
Voltage Compensation and Energy Supplement-Based Power Conversion System and Its Experimental Verification
Authors: Xi Zhansheng , Li Jianguo , Han Yufei , Zhang Yong , Wang Haijun
Published: November 2022

A voltage compensation and energy supplement-based power conversion system (VC-PCS) is proposed in this paper. A VC-PCS is a series connected to a battery that only processes fractional battery power; therefore, it has lower rated voltage and power in comparison with traditional PCSs. Compared with results of previous studies, the VC-PCS proposed herein can output bipolar voltage to meet voltage variation requirements and is a necessary and comprehensive improvement to previous research. First, its topology structure, working principle, and control strategy are comprehensively examined in this paper. Next, results of the simulations and physical experiments carried out are presented; the results show that the proposed VC-PCS is feasible in principle, and can be realized in physical applications.
Design and Analysis of a Series-Type Permanent Magnet Axial Flux-Switching Memory Machine
Authors: Li Nian , Xu Da , Hao Xiangjun , Li Jianhui
Published: November 2022

This paper presents a new topology of an axial flux-switching memory machine with series-type permanent magnets (SPMs) to improve the flux regulation capability. The key idea was to combine low coercive force (LCF) PMs, which can be magnetized and demagnetized readily, with high coercive force (HCF) PMs in series to provide a variable air-gap magnetic flux. The flux regulating principle and the forward magnetization effect of HCF PMs on LCF PMs are presented and discussed. Based on 3D finite element analysis (FEA), the magnetization variation of LCF PMs and the electromagnetic performances of the machine under different magnetization states were investigated. Simulation results showed that the air-gap magnetic flux could be weakened by up to 45% by using a magnetization current impulse, significantly extending the PM motor’s flux-weakening speed range. Finally, a prototype machine was built, and experiments were performed to validate the predictions. The basic experimental validation shows that the measured back-EMF and the flux regulating characteristic matched the 3D FEA results well.
A Review: Existing Methods for Solving Spatial Planning Problems for Wind Turbines in Poland
Authors: Amsharuk Artur , Łaska Grażyna
Published: November 2022

The article presents the most commonly used multi-criteria analysis methods for choosing the optimal location for future wind parks. The article makes a comparison of the criteria and restrictions of localisation and an overview of the main legal constraints and prospects in the development of renewable energy sources (RES). Financial assistance from the EU to accelerate the achievement of the required indicators was described. Moreover, restrictions considering environmental, social and noise factors that affect the life of the local population and the perception of the landscape visually are important. Additionally, it includes an option for developing wind energy in the absence of the necessary space for construction. In a new approach for the location of the wind farm, to the investors and another researcher related to the topic of wind turbine foundations, we indicate the most important aspects of wind energy control that should be taken into account in wind farm location proceedings.
Data Analytics for Admittance Matrix Estimation of Poorly Monitored Distribution Grids
Authors: Leal Pedro C. , Ferreira Diogo M. V. P. , Carvalho Pedro M. S.
Published: November 2022

Smart grid operations require accurate information on network topology and electrical equipment parameters. This paper proposes estimating such information with data from the smart grid. Assuming that the availability of bus voltage data is restricted to their magnitude, a linear model of the relationship between these data and the parameters of the admittance matrix is derived in a way that does not involve bus voltage angles. A regression optimizer is then proposed to minimize the deviation between data and values estimated by the linear model. Results on the IEEE 33 bus system are presented to illustrate the model accuracy and efficiency when used to estimate parameters of medium-voltage, three-phase balanced grids.
Measurement and Diagnosis of Comfort in a Historic Building
Authors: Fedorczak-Cisak Małgorzata , Kowalska-Koczwara Alicja , Nering Krzysztof , Pachla Filip , Radziszewska-Zielina Elżbieta , Stecz Piotr , Tatara Tadeusz , Jeleński Tomasz
Published: November 2022

Historic buildings constitute a specific group of buildings where the possibilities of improving energy efficiency and comfort are significantly limited because of the existing construction features and heritage values. Each building has a different history so the scope of renovation and/or retrofitting must be determined individually for each building. This article presents the methodology of measurement and diagnosis of features of particular importance for energy performance and comfort improvements, based on the example of a historic masonry building located in southern Poland. The first research question was which of the comfort conditions have been exceeded according to measurements. The second issue concerned the necessary extension of the basic determinants of comfort, beyond measurable qualities. A multi-faceted approach to the comfort assessment is proposed, including qualitative research that applies the additional criterion of aesthetic comfort. During the case study diagnosis, the acceptable level was exceeded in thermal, acoustic and aesthetic comfort. The first two may be addressed by optimized technical measures whilst the latter through a research-through-design that addresses the complex relationship between the perceiver and what the environment affords. The solution reflects the need to meet demands for retrofits that are energy-efficient and aesthetically pleasing while minimizing any negative impacts on the heritage and the environment.
Numerical Simulation of Gas Production and Reservoir Stability during CO2 Exchange in Natural Gas Hydrate Reservoir
Authors: Li Qingping , Li Shuxia , Ding Shuyue , Yin Zhenyuan , Liu Lu , Li Shuaijun
Published: November 2022

The prediction of gas productivity and reservoir stability of natural gas hydrate (NGH) reservoirs plays a vital role in the exploitation of NGH. In this study, we developed a THMC (thermal-hydrodynamic-mechanical-chemical) numerical model for the simulation of gas production behavior and the reservoir response. The model can describe the phase change, multiphase flow in porous media, heat transfer, and deformation behavior during the exploitation of NGH reservoirs. Two different production scenarios were employed for the simulation: depressurization and depressurization coupled with CO2 exchange. The simulation results suggested that the injection of CO2 promotes the dissociation of NGH between the injection well and the production well compared with depressurization only. The cumulative production of gas and water increased by 27.88% and 2.90%, respectively, based on 2000 days of production simulation. In addition, the subsidence of the NGH reservoir was lower in the CO2 exchange case compared with the single depressurization case for the same amount of cumulative gas production. The simulation results suggested that CO2 exchange in NGH reservoirs alleviates the issue of reservoir subsidence during production and maintains good reservoir stability. The results of this study can be used to provide guidance on field production from marine NGH reservoirs.
Frictional Pressure Drop for Gas–Liquid Two-Phase Flow in Coiled Tubing
Authors: Sun Shihui , Liu Jiahao , Zhang Wan , Yi Tinglong
Published: November 2022

Coiled tubing (CT) is widely used in drilling, workover, completion, fracturing and stimulation in the field of oil and gas exploration and development. During CT operation, the tubing will present a gas–liquid two-phase flow state. The prediction of frictional pressure drop for fluid in the tube is an important part of hydraulic design, and its accuracy directly affects the success of the CT technique. In this study, we analyzed the effects of the gas void fraction, curvature ratio and fluid inlet velocity on frictional pressure drop in CT, numerically. Experimental data verified simulated results. Flow friction sensitivity analysis shows the frictional pressure drop reaches its peak at a gas void fraction of 0.8. The frictional pressure gradient increases with the increase in curvature ratio. As the strength of secondary flow increases with the increase in inlet velocity, the increased trend of gas–liquid two-phase flow friction is aggravated. The correlation of friction factor for gas–liquid two-phase flow in coiled tubing is developed by regression analysis of simulation results. The research results can support high quality CT hydraulics design, through which the success of CT operations can be guaranteed.
Optimization of Exploration and Production Sharing Agreements Using the Maxi-Min and Nash Solutions
Authors: Balhasan Saad , Alnahhal Mohammed , Shawan Shahrul , Salah Bashir , Saleem Waqas , Tabash Mosab I.
Published: November 2022

Cooperation between supply chain partners in the oil industry is essential, especially when oil prices suffer from fluctuations that affect the profitability of each party. An essential task in oil field development projects is to create an optimum agreement between the national oil company and the international oil company to guarantee agreement optimization. In this paper, the national oil company is the first party (FP) and the international oil company is the second party (SP). The paper’s purpose is to investigate the use of game theory to obtain the best agreement between the FP and SP in order to enhance the cooperation and reduce conflict. In this paper, Nash and Maxi-min solutions have been applied for the first time in a special type of petroleum agreement, called exploration and production sharing agreements (EPSA). This is conducted for a case study in Libya. The study considers nine negotiation factors (issues) in the EPSA, which are the share percent, the four “A” factors, and the four “B” factors, which are usually affected by the fluctuations of oil prices; and the study investigates their effect on the total payoff function, the net present value (NPV), and internal rate of return (IRR) for both parties. The Maxi-min solution has shown an improvement in the NPV and IRR of the SP, where NPV increased from USD 148 million to USD 195 million, and IRR from 15.65% to 17.01%. The Nash solution has shown a little more improvement than the Maxi-min solution in the NPV and IRR for the SP, where the NPV and IRR have increased from USD 148 million to USD 222 million and from 15.65% to 17.94%, respectively.
Economic Conditions to Circularize Clinical Plastics
Authors: Sadhukhan Jhuma , Sekar Kartik
Published: November 2022

Over 5.5 million tons of plastic waste are generated globally from the research sectors. A university laboratory, e.g., pathology, can generate 250 tons of clinical plastic waste annually. The UK National Health Service (NHS) generates 133 kilotons (kt) of clinical plastic waste annually. Healthcare facilities in the US generate 1.7 million tons of clinical plastic waste annually. In addition, 95% of the clinical plastics are single-use plastics derived from fossil resources, i.e., crude oils. These single-use clinical plastic wastes are incinerated, contributing to global warming, or go to the landfill, contributing to resource depletion. Plastic leakage is a major threat to the environment. This linear plastics economy model, take-make-dispose, must be replaced by a circular plastics economy, i.e., sort plastic wastes, wash, decontaminate, recover materials, blend with bio-based compounds as necessary and circulate recyclate plastics, for holistic systemic sustainability. While there are multi-faceted environmental drivers for a circular plastics economy, there are many uncertainties in the economic attributes, electricity price, labor cost and chemical cost being the primary ones influencing the cost of production of secondary or recyclate plastics, requiring government and policy support, such as a gate fee on plastic waste by the generators to the recyclers. An essential macroeconomic condition for techno-economically (or micro-economically) feasible plastic waste recycling is low oil and gas prices that influence the recyclate plastics and electricity prices. It is essential to de-fossilize the economy by decoupling renewable electricity generation from natural gas consumption and fossil-independent biopolymer productions displacing fossil-derived plastics to stimulate the circular economy. This study shows a comprehensive and robust technoeconomic analysis of mechanical recycling of clinical plastic wastes into secondary plastics recovery.
Performance Analysis and Optimization for Static Mixer of SCR Denitration System under Different Arrangements
Authors: Pang Zhanzhou , Chen Ranjing , Cao Yue
Published: November 2022

In order to solve the poor flow performance issues of selective catalytic reduction (SCR) denitration systems, the effect of the static mixer on the flow field was studied using computational fluid dynamics (CFD) numerical simulations. Based on the analysis of the original SCR denitration system, two static mixers were selected to explore their influence on system performance. The results show that both static mixers can effectively improve the denitration performance under different conditions. The static mixer with a rotating arrangement showed a better performance in the uniformity of concentration. The pressure loss without a static mixer is 834 Pa, and the pressure loss increases by 94 Pa and 73 Pa for rotating and X-arranged static mixers, respectively. Meanwhile, a static mixer will increase energy loss. Therefore, power plants can choose the layout of their static mixers according to the actual situation to achieve the optimal performance.
PID Control of a Superheated Steam Temperature System Based on Integral Gain Scheduling
Authors: Cui Xiaobo , Xu Pan , Song Guohui , Gu Haiming , Gu Hui , Wang Liang , Zhu Hongxia
Published: November 2022

The high-quality operation of a superheated steam temperature (SST) system is a core fact of the safety, economy, and stability of thermal power units. How to improve the control performance of an SST system under large-varying operating conditions is becoming a research hotspot. To solve this challenge, this paper proposes a proportional integral derivative (PID) control strategy based on integral gain scheduling. Based on the introduction of the SST system and classical model under typical operating conditions, the control difficulties of the SST system are analyzed theoretically. Then, a PID control strategy, based on integral gain scheduling, is introduced for the cascade control structure, and the stability of the proposed control strategy is analyzed by calculating the PID stability region. Finally, the effectiveness of the proposed method is verified under nominal and uncertain conditions, where the proposed method could obtain satisfactory tracking and disturbance rejection control performance. Simulation results show the valuable application prospects of the proposed method.
Thin-Film Lithium Cobalt Oxide for Lithium-Ion Batteries
Authors: Duan Zeqing , Wu Yunfan , Lin Jie , Wang Laisen , Peng Dong-Liang
Published: November 2022

Lithium cobalt oxide (LCO) cathode has been widely applied in 3C products (computer, communication, and consumer), and LCO films are currently the most promising cathode materials for thin-film lithium batteries (TFBs) due to their high volumetric energy density and favorable durability. Most LCO thin films are fabricated by physical vapor deposition (PVD) techniques, while the influence of preparation on the materials’ properties and electrochemical performance has not been highlighted. In this review, the dominant effects (heating, substrate, power, atmosphere, etc.) on LCO thin films are summarized, and the LCO thin films fabricated by other techniques (spin coating, sol–gel, atomic layer deposition, pulsed laser deposition, etc.) are outlined. Moreover, the modification strategies including bulk doping and surface coating for powder and thin-film LCO electrodes are discussed in detail. This review may pave the way for developing novel, durable, and high-performance LCO thin films by versatile methods for TFB and other energy storage devices.
Significance and Challenges of Poultry Litter and Cattle Manure as Sustainable Fuels: A Review
Authors: Maj Izabella
Published: November 2022

Growing animal production results in a significant amount of waste, composed of manure, bedding, feed, feathers, etc., whose safe and cost-effective disposal becomes a troublesome challenge. The literature review points out that the higher heating value (HHV) of animal-origin waste reaches 19 MJ/kg (dry basis), which positions it as a promising renewable energy source. Various paths of energy recovery were investigated in the literature, but the thermal processes, particularly combustion and co-combustion, were indicated as the most effective from both technical and environmental points of view. The presented study reviews the fuel characteristics, possible combustion-related challenges, and ash disposal routes of the most popular animal-origin waste: poultry litter and cow (cattle) manure with a slight sight on piggery (swine) manure. When considering animal-origin feedstock as fuel, usually only animal species is given (poultry, cattle, etc.). However, according to the analyzed literature data, this is not sufficient information. Several more factors crucially influence the fuel and ash properties of animal waste and the most vital are: the housing system, type of bedding, and farming style. Animal litter is considered a “difficult” fuel, nevertheless, it does not always cause combustion-related problems. Some analyzed feedstock feature low chlorine concentrations and high ash melting temperatures, which makes them combustion-friendly.
Multi-Objective Optimization for Peak Shaving with Demand Response under Renewable Generation Uncertainty
Authors: Wynn Sane Lei Lei , Pinthurat Watcharakorn , Marungsri Boonruang
Published: November 2022

With high penetration of renewable energy sources (RESs), advanced microgrid distribution networks are considered to be promising for covering uncertainties from the generation side with demand response (DR). This paper analyzes the effectiveness of multi-objective optimization in the optimal resource scheduling with consumer fairness under renewable generation uncertainty. The concept of consumer fairness is considered to provide optimal conditions for power gaps and time gaps. At the same time, it is used to mitigate system peak conditions and prevent creating new peaks with the optimal solution. Multi-objective gray wolf optimization (MOGWO) is applied to solve the complexity of three objective functions. Moreover, the best compromise solution (BCS) approach is used to determine the best solution from the Pareto-optimal front. The simulation results show the effectiveness of renewable power uncertainty on the aggregate load profile and operation cost minimization. The results also provide the performance of the proposed optimal scheduling with a DR program in reducing the uncertainty effect of renewable generation and preventing new peaks due to over-demand response. The proposed DR is meant to adjust the peak-to-average ratio (PAR) and generation costs without compromising the end-user’s comfort.
Thermal Perturbations at Crystal Nucleation in Glass-Forming Liquids
Authors: Minakov Alexander , Schick Christoph
Published: November 2022

Understanding the processes occurring during the nanocrystallization of glass-forming liquids is important for creating artificial nanostructures for various applications. In this article, local thermal perturbations in supercooled glass-forming liquids and polymers during the nucleation of a crystalline phase are studied. To describe the thermal response of supercooled glass-forming liquids, an integro-differential heat equation with dynamic heat capacity is used. We have found that the effect of the dynamic heat capacity is significant for fast local thermal perturbations that arise in the early stages of crystal nucleation in glass-forming liquids and polymers. It has been established that local temperature perturbations during the nucleation of crystals in silicate glasses and polymers can change the nucleation rate by 2–5 orders of magnitude. The knowledge gained can be useful for the technology of artificial microstructures and advanced materials.
Improving the Efficiency of Earth Fault Detection by Fault Current Passage Indicators in Medium-Voltage Compensated Overhead Networks
Authors: Olejnik Bartosz , Zięba Beata
Published: November 2022

The article presents a method for detecting earth faults in a compensated medium-voltage network, which can be used especially in fault current passage indicators, but also in standard protection devices. The method is based on the adaptation process of the zero-sequence current protection setting, with the adaptation factor depending on the current value of the zero-sequence voltage. In this article, a comparative analysis of the classical and adaptive zero-sequence current criterion is conducted, taking into account the errors of the measuring system. The results of simulations performed in the PSCad environment are also presented. For a representative set of example short circuits, it was shown that the effectiveness of the presented criterion can be more than 50% higher than that of the standard criteria, taking into account the range of detected transition resistances. A comparison of the proposed method with admittance criteria was also drawn, and it was shown that it is suitable for the detection of high-resistance earth faults.
An Effective Hybrid Symbolic Regression–Deep Multilayer Perceptron Technique for PV Power Forecasting
Authors: Trabelsi Mohamed , Massaoudi Mohamed , Chihi Ines , Sidhom Lilia , Refaat Shady S. , Huang Tingwen , Oueslati Fakhreddine S.
Published: November 2022

The integration of Photovoltaic (PV) systems requires the implementation of potential PV power forecasting techniques to deal with the high intermittency of weather parameters. In the PV power prediction process, Genetic Programming (GP) based on the Symbolic Regression (SR) model has a widespread deployment since it provides an effective solution for nonlinear problems. However, during the training process, SR models might miss optimal solutions due to the large search space for the leaf generations. This paper proposes a novel hybrid model that combines SR and Deep Multi-Layer Perceptron (MLP) for one-month-ahead PV power forecasting. A case study analysis using a real Australian weather dataset was conducted, where the employed input features were the solar irradiation and the historical PV power data. The main contribution of the proposed hybrid SR-MLP algorithm are as follows: (1) The training speed was significantly improved by eliminating unimportant inputs during the feature selection process performed by the Extreme Boosting and Elastic Net techniques; (2) The hyperparameters were preserved throughout the training and testing phases; (3) The proposed hybrid model made use of a reduced number of layers and neurons while guaranteeing a high forecasting accuracy; (4) The number of iterations due to the use of SR was reduced. The presented simulation results demonstrate the higher forecasting accuracy (reductions of more than 20% for Root Mean Square Error (RMSE) and 30 % for Mean Absolute Error (MAE) in addition to an improvement in the R2 evaluation metric) and robustness (preventing the SR from converging to local minima with the help of the ANN branch) of the proposed SR-MLP model as compared to individual SR and MLP models.
Assessment of the Annual Erosion Rate along Three Hiking Trails in the Făgăraș Mountains, Romanian Carpathians, Using Dendrogeomorphological Approaches of Exposed Roots
Authors: Jula Mihai , Voiculescu Mircea
Published: November 2022

Mountain hiking trails are vital components of tourist infrastructure and provide recreational opportunities for a large number of tourists. Exposed roots along the tourist trails in the forested mountains are impacted by tourist trampling and various natural processes, thus becoming even more exposed and eroded. The aim of our study was to estimate the annual erosion rates along three hiking trails in the Făgăraș Mountains using dendrogeomorphological approaches. The three used routes were: Bâlea Hotel—Bâlea Waterfall (BWFHT), Bâlea Hotel—Bâlea Glacial Lake (BLHT), and Bâlea Hotel—Doamnei Glacial Valley (DVHT). The average annual erosion rates in BWFHT, BLHT, and DVHT were 10.6 ± 4.4, 6.8 ± 3.9, and 6.1 ± 3.3 mm·y−1, respectively. Over a 56-year interval (1965–2021), 610 scars were recorded among the annual growth rings of the sampled tree roots; 172, 213, and 225 scars were recorded in BWFHT, BLHT, and DVHT, respectively. Moreover, we identified 1022 rows of traumatic resin ducts (TRDs) associated with scars: 237, 343, and 442 in BWFHT, BLHT, and DVHT, respectively. Additionally, the climate of the Făgăraș Mountains is humid with a multiannual average precipitation of 1366.2 mm; the precipitation in 24 h, between 1979 and 2021 in seven and three cases exceeded 70 mm/24 h and 100 mm/24 h, respectively. Thus, there were synchronous situations of root exposure with 24 h rainfall. However, it is unclear whether precipitation plays a decisive role in root exposure or in triggering erosion processes on tourist trails. We considered that tourist traffic plays a decisive role in root exposure and erosion, however locally and complementarily, 24 h precipitation must also be considered.
Transpiration Sensitivity to Drought in Quercus wutaishansea Mary Forests on Shady and Sunny Slopes in the Liupan Mountains, Northwestern China
Authors: Liu Bingbing , Yu Pengtao , Zhang Xue , Li Jiamei , Yu Yipeng , Wan Yanfang , Wang Yanhui , Wang Xiao , Liu Zebin , Pan Lei , Xu Lihong
Published: November 2022

Forests in water source areas are important factors for water supply security, soil, and water conservation, and their water consumption from transpiration is strongly affected by site conditions, including the slope aspect. However, the lack of research on how the slope aspect interferes with the response of stand transpiration to drought has hindered researchers from developing climate-resilient forest–water coordinated, sustainable development plans for different stand conditions. This study was conducted on Quercus wutaishansea forests in the southern part of Liupan Mountain in northwest China, and two sample plots were built on sunny and shady slopes. The responses of stand transpiration to various soil moisture and meteorological conditions on different slope orientations were analyzed. The results showed better-growing stands on shady slopes transpired more and consumed more soil moisture than those on sunny slopes. The soil moisture on shady slopes decreased rapidly below the threshold level during the drought, leading to a limitation of stand transpiration; however, its transpiration recovered rapidly after the drought. In contrast, stand transpiration on sunny slopes was not affected by this drought and maintained its pre-drought rate. Our results suggested that stands with higher water demand on shady slopes were more susceptible to drought when it occurred. This indicated that in the case of frequent droughts, the vegetation should be managed according to the vegetation-carrying capacities resulting from different site conditions.
Effects of Plot Design on Estimating Tree Species Richness and Species Diversity
Authors: Zhao Chenhao , Zhu Yan , Meng Jinghui
Published: November 2022

Species richness and diversity substantially affect forest structures and function and are critical indicators of sustainable forest management. Sampling surveys are widely used in forest inventories because they efficiently assess forest characteristics. However, an appropriate sample plot design is required. The objectives of this study were to evaluate the effects of plot design on estimating species richness and species diversity using a simulation. A 20 ha census plot was established in a temperate forest to obtain the true values of species richness and species diversity. One single plot design and nine cluster plot designs were evaluated. The results indicated significant differences in forest species richness and species diversity for different plot designs. The cluster plot design with a square subplot configuration (SCONFIG) and extent of ground area covered by a cluster (EGROUND) of 500 m2 exhibited the best performance (accuracy, precision) in estimating forest species richness. In contrast, a rectangular cluster plot with an EGROUND of 1000 m2 was more suitable for assessing species diversity. This study demonstrates that cluster plots outperform a single plot for evaluating species richness and species diversity in temperate forests.
Staple Holding Strength of Furniture Frame Joints Constructed of Plywood and Solid Wood
Authors: Miao Yanfeng , Pan Sheng , Xu Wei
Published: November 2022

The withdrawal and lateral holding properties of three types of plywood with one stapled as well as one-row multi-stapled joints were studied and compared. The results show that variations in plywood density have a significant effect on withdrawal strength and a relatively small effect on lateral holding strength. At four staples, the withdrawal strength of the eucalyptus plywood with a density of 0.59 g/cm3 is 1821 N, which is 21% higher than that of poplar plywood with a density of 0.51 g/cm3 at 1498 N and 32% higher than that of eucalyptus/poplar composite plywood with a density of 0.53 g/cm3 at 1275 N. In terms of lateral holding strength, eucalyptus plywood has a lateral holding strength of 1603 N 12% lower than the 1807 N of eucalyptus/poplar composite plywood and 10% lower than the 1761 N of poplar plywood. As the number of staples increased from 1 to 4 in increments of 1, the withdrawal strength of eucalyptus plywood continued to increase, while the nodal strengths of the poplar plywood as well as eucalyptus/poplar composite plywood did not differ significantly between 3 and 4 staples, and there is a significant increase in the lateral holding strength for all three plywood nodes. Equations for predicting the withdrawal and lateral holding strengths of one-row multi-stapled joints were derived separately.