bluuebunny/crossref_metadata_2025 huggingface dataset:
A Novel Anchor-Free Localization Method Using Cross-Technology Communication for Wireless Sensor Network
Authors: Jing Nan , Zhang Bowen , Wang Lin
Published: December 2022

In recent years, wireless sensor networks have been used in a wide range of indoor localization-based applications. Although promising, the existing works are dependent on a large number of anchor nodes to achieve localization, which brings the issues of increasing cost and additional maintenance. Inspired by the cross-technology communication, an emerging technique that enables direct communication among heterogeneous wireless devices, we propose an anchor-free distributed method, which leverages the installed Wi-Fi APs to range instead of traditional anchor nodes. More specifically, for the asymmetric coverage of Wi-Fi and ZigBee nodes, we first design a progressive method, where the first unknown node estimates its location based on two Wi-Fi APs and a sink node, then once achieving its position, it acts as the alternative sink node of the next hop node. This process is repeated until the new members can obtain their positions. Second, as a low-power technology, ZigBee signal may be submerged in strong signal such as Wi-Fi. To overcome this problem, a maximum prime number is deployed to be the Wi-Fi broadcasting period based on the numerical analysis theory. Among many of prime numbers, we have the opportunity to select an appropriate one to achieve full coverage with the relatively small packet collisions. Last, simulations and experiments are performed to evaluate the proposal. The evaluation results show that the proposal can achieve decimeter level accuracy without deploying any anchor node. Moreover, the proposal demonstrates the anti-interference ability in the crowded open spectrum environment.
Improved High-Order Cumulant TDE Parameter Accumulation Algorithm for Locating UHF Signals of Pulsed Electromagnetic Source
Authors: Zhu Li , Zhang Yue , Hu Xiaofeng , Dong Yu
Published: December 2022

Ultra-high frequency (UHF) signal detection is one of the most effective methods for spatial orientation and partial discharge fault diagnosis. However, when the background noise, especially Gaussian white noise and narrow-band interference, is very high, or the detection region is remote, location accuracy may decrease. To improve this, a location system based on the improved higher-order cumulant time delay estimation (TDE) method combined with energy accumulation is proposed. In the system, the UHF waves are received by a four-antenna array. Improved fourth-order cumulants with a smoothed coherence transform (SCOT) window are used in the TDE, by which Gaussian white noise and narrow-band interference can be efficiently suppressed. The energy accumulation algorithm is applied to the cross-correlation results, by which the accuracy of TDE can be enhanced. The applicability of the proposed localization algorithm is evaluated by simulation and experiment. The simulation results show that the improved fourth-order cumulant TDE-parameter accumulation algorithm is superior in accuracy to traditional location methods. In the experimental measurements, two partial discharge measurement points located in a complex electromagnetic environment are tested. The results illustrate that the proposed method can effectively suppress Gaussian white and narrow-band noise, and the location results can satisfy accuracy requirements when the measurement point is within 70 m.
Tabular Open Circuit Voltage Modelling of Li-Ion Batteries for Robust SOC Estimation
Authors: Sundaresan Sneha , Devabattini Bharath , Kumar Pradeep , Pattipati Krishna , Balasingam Balakumar
Published: December 2022

Battery management systems depend on open circuit voltage (OCV) characterization for state of charge (SOC) estimation in real time. The traditional approach to OCV-SOC characterization involves collecting OCV-SOC data from sample battery cells and then fitting a polynomial model to this data. The parameters of these polynomial models are known as the OCV-parameters, or OCV-SOC parameters, in battery management systems and are used for real-time SOC estimation. Even though traditional OCV-SOC characterization approaches are able to abstract the OCV-SOC behavior of a battery in a few parameters, these parameters are only applicable in high precision computing systems. However, many practical battery applications do not have access to high-precision computing resources. The typical approach in a low-precision system is to round the OCV-parameters. This paper highlights the perils of rounding the OCV parameters and proposes an alternative OCV-SOC table. First, several existing OCV-SOC parameters are compared in terms of their expected system requirements and accuracy losses due to rounding. Then, a systematic optimization-based approach is introduced to create an OCV-SOC table that is robust to rounding. A formal performance evaluation metric is introduced to measure the robustness of the resulting OCV-SOC table. It is shown that the OCV-SOC table obtained through the proposed optimization approach outperforms the traditional parametric OCV-SOC models with respect to rounding.
Analysis of the Future of Mobility: The Battery Electric Vehicle Seems Just a Transitory Alternative
Authors: Cremades Lázaro , Canals Casals Lluc
Published: December 2022

It is, undoubtedly, a widespread belief that the electric vehicle (EV) is considered sustainable. However, in the manufacturing and retirement phases, EVs do not appear to be as sustainable as internal combustion vehicles (ICVs) and during the use phase, the pollution produced by EVs depends on the source of electricity generation to recharge the batteries. From an economic point of view, EVs do not appear to be competitive compared to ICVs either. However, current market trends push hard on battery EVs (BEV) and plug-in hybrid vehicles (PHEV). This study aims to analyze which of the possible mobility alternatives has more sense to be considered as the option with higher penetration in the future. To this end, four known mobility technologies (ICVs, PHEVs, BEVs, and hydrogen fuel cell EVs or FCEVs) are compared for a mid-size car using published data, through environmental and techno-economic criteria, by applying the analytic hierarchy process method in an objective manner on multiple scenarios. Putting all criteria together, it seems that the ICV alternative is the one receiving the best results in most of the scenarios, except in the case where the environmental criteria have the greatest weight. The BEV solution has almost always turned out to be the worst alternative, but it is the only choice we have right now.
Power-to-Methane to Integrate Renewable Generation in Urban Energy Districts
Authors: Lo Basso Gianluigi , Pastore Lorenzo Mario , de Santoli Livio
Published: December 2022

The deployment of distributed energy systems must take place paying attention to the self-consumption of renewable generation. Innovative sector coupling strategies can play that role linking local electricity and gas grids. The present work aims to evaluate the energy and economic feasibility of the Power-to-Methane strategy application in urban energy districts. A residential cluster was considered as a case study. Two PV configurations have been applied to evaluate the Substitute Natural Gas (SNG) production under different renewable excess conditions. Thereafter, the Power-to-Methane strategy was implemented by varying the system’s size. Some significant configurations have been compared to each other in terms of energy and economics. Beyond a certain threshold limit, an increase in the photovoltaic size slightly enhances the effectively self-consumed energy. The Power-to-Methane strategy can exploit all the renewable excess once the system is properly sized, almost doubling the potential energy consumption reduction compared to the PV system alone. The SNG production cost is between 100 and 200 EUR/MWh in most configurations, which is competitive with the high natural gas prices on the European market. Therefore, decentralised SNG production can reduce the households’ annual expenditures and it can mitigate the energy poverty conditions over the current energy crisis period.
An Underactuated Universal Gripper: Design, Analysis, and Experiment
Authors: Wang Chunguang , Zhou Yulin , Xie Bing , Xie Jiuming , Zhang Junsheng
Published: December 2022

As the working tool of the robot, the importance of the gripper becomes more prominent with the extensive use of the robot. This paper proposes a new type of underactuated universal gripper that can be applied to handle lightweight parts of any shape. It integrates a crank train and a four-bar mechanism to grasp objects. The kinematics and statics analysis of the proposed gripper were carried out; and in this paper, we briefly introduce the concept and control system design. Then, the motion characteristics and grasping ability of the underactuated gripper are presented. A prototype of the gripper was designed and manufactured based on the simulation analysis, and relevant grasping experiments were carried out. The experimental results verify that the proposed universal gripper has the advantages of safe design, easy manufacturing, effective gripping, and stable holding of objects.
Application of Gas Dissolved in Fuel in the Aspect of a Hypocycloidal Pump Design
Authors: Bajerlein Maciej , Karpiuk Wojciech , Smolec Rafał
Published: December 2022

The advancement of modern injection systems of diesel engines is related to a constant increase in the injection pressures generated by injection pumps. This translates into an improvement of the engine operation indexes, including the emission-related ones. Such an approach brings a series of problems related to the design, construction and durability of the injection system. Therefore, the authors asked whether the current market trend in injection systems is the only appropriate path to be taken. When searching for the answer, the authors decided to propose an innovative concept consisting of dissolving exhaust gas in diesel fuel with the use of an injection pump. Such a saturated solution, when flowing out of the injection nozzle, begins the process of releasing the gas dissolved in the fuel. This has a positive impact on the atomization process, hence the process of combustion. The aim of this paper stems from the previously performed research. Due to the nature of the phenomenon, it was necessary to propose a new design for the injection pump. For correct selection of the dimensions of the pumping section, it was of key importance to determine the coefficient of solubility and the bulk modulus of the solution of diesel fuel and exhaust gas. Aside from the description of the applied method and the results of the direct measurements, this paper presents the yet undescribed results of the measurements of the coefficient of solubility of different concentrations of exhaust gas in diesel fuel. The authors also investigated the influence of the amount of exhaust gas dissolved in the fuel on the bulk modulus of the solution. The final part of the paper is a description of a proprietary design of a hypocycloidal injection pump. The application of the innovative drive allows a correct dissolution of exhaust gas in the fuel.
Solar Energy and Biomass within Distributed Generation for a Northeast Brazil Hotel
Authors: de Lima Karollyne , de Mello Delgado Danielle , Martins Dener , Carvalho Monica
Published: December 2022

Besides satisfying the energy demands of buildings, distributed generation can contribute toward environmental conservation. However, determining the best configuration and operational strategy for these systems is a complex task due to the available technology options and the dynamic operating conditions of buildings and their surroundings. This work addressed the synthesis and optimization of an energy system for a commercial building (hotel). Electricity, hot water, and cooling demands were established for a hotel located in Northeast Brazil. The optimization problem was based on mixed-integer linear programming and included conventional equipment, solar energy resource (photovoltaic and thermal technologies), and biomass. The objective function of the optimization was to minimize annual economic costs, which involved considering the capital and operation costs. A reference system was established for comparison purposes, where energy demands were met conventionally (without cogeneration or renewable energy), whose annual cost was BRL 80,799. Although the optimal solution did not rely on cogeneration, it benefited from the high degree of energy integration and had a total annual cost of BRL 24,358 (70% lower). The optimal solution suggested the installation of 70 photovoltaic panels and used biomass (sugarcane bagasse) to operate a hot water boiler. Solar collectors for hot water production were not part of the optimal solution. Sensitivity analyses were also carried out, varying the electricity and natural gas tariffs, and the type of biomass employed, but the configuration of the system did not change compared with the optimal economic solution.
Optimal Ultra-Local Model Control Integrated with Load Frequency Control of Renewable Energy Sources Based Microgrids
Authors: Bakeer Abualkasim , Magdy Gaber , Chub Andrii , Jurado Francisco , Rihan Mahmoud
Published: December 2022

Since renewable energy sources (RESs) have an intermittent nature, conventional secondary frequency control, i.e., load frequency control (LFC), cannot mitigate the effects of variations in system frequency. Thus, this paper proposes incorporating ultralocal model (ULM) control into LFC to enhance microgrid (µG) frequency stability. ULM controllers are regarded as model-free controllers that yield high rejection rates for disturbances caused by load/RES uncertainties. Typically, ULM parameters are set using trial-and-error methods, which makes it difficult to determine the optimal values that will provide the best system performance and stability. To address this issue, the African vultures optimization algorithm (AVOA) was applied to fine-tune the ULM parameters, thereby stabilizing the system frequency despite different disturbances. The proposed LFC controller was compared with the traditional secondary controller based on an integral controller to prove its superior performance. For several contingencies, the simulation results demonstrated that the proposed controller based on the optimal ULM coupled with LFC could significantly promote RESs into the µG.
An Optimization Study on the Operating Parameters of Liquid Cold Plate for Battery Thermal Management of Electric Vehicles
Authors: Wei Lichuan , Zou Yanhui , Cao Feng , Ma Zhendi , Lu Zhao , Jin Liwen
Published: December 2022

The development of electric vehicles plays an important role in the field of energy conservation and emission reduction. It is necessary to improve the thermal performance of battery modules in electric vehicles and reduce the power consumption of the battery thermal management system (BTMS). In this study, the heat transfer and flow resistance performance of liquid cold plates with serpentine channels were numerically investigated and optimized. Flow rate (m˙), inlet temperature (Tin), and average heat generation (Q) were selected as key operating parameters, while average temperature (Tave), maximum temperature difference (ΔTmax), and pressure drop (ΔP) were chosen as objective functions. The Response Surface Methodology (RSM) with a face-centered central composite design (CCD) was used to construct regression models. Combined with the multi-objective non-dominated sorting genetic algorithm (NSGA-II), the Pareto-optimal solution was obtained to optimize the operation parameters. The results show that the maximum temperature differences of the cold plate can be controlled within 0.29~3.90 °C, 1.11~15.66 °C, 2.17~31.39 °C, and 3.43~50.92 °C for the discharging rates at 1.0 C, 2.0 C, 3.0 C, and 4.0 C, respectively. The average temperature and maximum temperature difference can be simultaneously optimized by maintaining the pressure drop below 1000 Pa. It is expected that the proposed methods and results can provide theoretical guidance for developing an operational strategy for the BTMS.
A Comparison between Statistical Behaviours of Scalar Dissipation Rate between Homogeneous MILD Combustion and Premixed Turbulent Flames
Authors: Young Frederick W. , Awad Hazem S. A. M. , Abo-Amsha Khalil , Ahmed Umair , Chakraborty Nilanjan
Published: December 2022

Three-dimensional Direct Numerical Simulations (DNS) data has been utilised to analyse statistical behaviours of the scalar dissipation rate (SDR) and its transport for homogeneous methane-air mixture turbulent Moderate or Intense Low oxygen Dilution (MILD) combustion for different O2 dilution levels and turbulence intensities for different reaction progress variable definitions. Additional DNS has been conducted for turbulent premixed flames and passive scalar mixing for the purpose of comparison with the SDR statistics of the homogeneous mixture MILD combustion with that in conventional premixed combustion and passive scalar mixing. It has been found that the peak mean value of the scalar dissipation rate decreases with decreasing O2 concentration for MILD combustion cases. Moreover, SDR magnitudes increase with increasing turbulence intensity for both MILD and conventional premixed combustion cases. The profiles and mean values of the scalar dissipation rate conditioned upon the reaction progress variable are found to be sensitive to the choice of the reaction progress variable definition. This behaviour arises due to the differences in the distributions of the species mass fractions within the flame. The strain rate contribution and the molecular dissipation term are found to be the leading order contributors in the scalar dissipation rate transport for MILD combustion; whereas, in conventional premixed flames, the terms rising from density variation and reaction rate gradient also play leading roles in addition to the strain rate and molecular dissipation contributions. By contrast, the terms due to density gradient and reaction rate gradient remain negligible in comparison to the leading order contributors in MILD combustion cases due to small density variation because of moderate temperature rise and small reaction rate gradient magnitudes. Furthermore, the qualitative behaviour of the strain rate contribution to the SDR transport in premixed flames is significantly different to that in the case of MILD combustion and passive scalar mixing. The findings of the current analysis indicate that the scalar dissipation rate statistics in MILD combustion show several qualitative similarities to the passive scalar mixing despite major differences with the SDR transport in conventional turbulent premixed flames. This further suggests that the scalar dissipation rate models, which were originally proposed in the context of passive scalar mixing, have the potential to be applicable for MILD combustion but the models for the premixed turbulent combustion may not be applicable for MILD combustion of homogeneous mixtures.
Data Compensation with Gaussian Processes Regression: Application in Smart Building’s Sensor Network
Authors: Phan Anh Tuan , Vu Thi Tuyet Hong , Nguyen Dinh Quang , Sanseverino Eleonora Riva , Le Hang Thi-Thuy , Bui Van Cong
Published: December 2022

Data play an essential role in the optimal control of smart buildings’ operation, especially in building energy-management for the target of nearly zero buildings. The building monitoring system is in charge of collecting and managing building data. However, device imperfections and failures of the monitoring system are likely to produce low-quality data, such as data loss and inconsistent data, which then seriously affect the control quality of the buildings. This paper proposes a new approach based on Gaussian process regression for data-quality monitoring and sensor network data compensation in smart buildings. The proposed method is proven to effectively detect and compensate for low-quality data thanks to the application of data analysis to the energy management monitoring system of a building model in Viet Nam. The research results provide a good opportunity to improve the efficiency of building energy-management systems and support the development of low-cost smart buildings.
Piezoelectric Harvesting of Fluid Kinetic Energy Based on Flow-Induced Oscillation
Authors: Xu Ya , Yuan Jiangqi , Sun Daming , Xie Dailiang
Published: December 2022

Flow-induced oscillations widely exist in pipelines, fluid machinery, aerospace, and large-span flexible engineering structures. An inherent energy conversion mechanism can be developed for fluid kinetic energy utilization or acoustic energy harvesting. Fluid-resonant acoustic oscillation is featured by stability, easy operation, and a simple mechanical structure. Acoustic oscillation has high intensity and a mono-frequency, which is beneficial for energy harvesting. A simple cavity with appropriate structural dimensions that can induce fluid-resonant oscillations is set and combined with piezoelectric technology to generate electric power. The energy conversion mechanism is studied numerically and experimentally. The effects of flow velocity on the acoustic frequency, the pressure amplitude, and the output voltage of piezoelectric transducer are analyzed. A stable standing wave acoustic field can be generated in the cavity in a certain range of flow velocity. The results show that the higher intensity acoustic field occurs in the first acoustic mode and the first hydraulic mode and can be obtained in the range of flow velocity 27.1–51.1 m/s when the cavity length is 190 mm. A standing wave acoustic field occurs with a frequency of 490 Hz and a maximum pressure amplitude of 15.34 kPa. The open circuit output voltage can reach 0.286 V using a preliminary transducer. The device designed based on this method has a simple structure and no moving parts. It can harvest the fluid kinetic energy that widely exists in pipelines, engineering facilities, air flow forming around transportation tools, and the natural environment. Its energy output can be provided for the self-powered supply system of low-power sensor nodes in wireless sensor networks.
Sintering of Industrial Uranium Dioxide Pellets Using Microwave Radiation for Nuclear Fuel Fabrication
Authors: Pilyushenko Konstantin , Dmitriyev Maxim , Vinokurov Sergey , Trofimov Trofim , Saveliyev Boris , Kuznetsov Alexander , Uvarov Alexander , Myasoedov Boris
Published: December 2022

In this study, the possibility of sintering industrial pressed uranium dioxide pellets using microwave radiation for the production of nuclear fuel is shown. As a result, the conditions for sintering pellets in an experimental microwave oven (power 2.9 kW, frequency 2.45 GHz) were chosen to ensure that the characteristics of the resulting fuel pellets meet the regulatory requirements for ceramic nuclear fuel, including the following: a density of about 10.44 g/cm3; a volume fraction of open pores of tablets of about 0.1%; an oxygen coefficient of no more than 2.002; hydrogen content of about 0.30 ppm; and the change in density after re-sintering on average no more than 1.16%.
Stannous Tungstate Semiconductor for Photocatalytic Degradation and Photoelectrochemical Water Splitting: A Review
Authors: Qiu Weixin , Liu Yang
Published: December 2022

The use of photocatalysis and photoelectrocatalysis is expected to achieve the efficient utilization of solar energy to alleviate and even solve the problems of energy depletion and environmental pfollution. At present, stannous tungstate materials have attracted extensive attention in the fields of photocatalysis and photoelectrocatalysis as favorable candidates for such utilization because of their narrow band gap energy (which is ~1.7 eV for the α phase and ~2.7 eV for the β phase, respectively) and unique band structure (which covers the oxidation and reduction potential of water). However, their practical application is still limited by excessive electron–hole recombination and poor stability. In this review, basic information (crystal and electronic structures) related to photocatalysis and photoelectrocatalysis is presented. Additionally, various strategies to enhance the photocatalytic and photoelectrochemical properties of stannous tungstate materials, such as morphological modification, crystal facet engineering, doping modification, and multicomponent compositing, are summarized. Furthermore, the achievements and difficulties of the relevant studies are discussed. The information presented in this review can provide a reference for subsequent research on the photocatalytic and photoelectrochemical performance of tungstate-based materials.
Characteristics of Hydrothermal Carbonization Hydrochar Derived from Cattle Manure
Authors: Song Eunhye , Park Seyong , Han Seongkuk , Lee Eusil , Kim Ho
Published: December 2022

The characteristics of hydrothermal carbonization hydrochar derived from cattle manure including excrements and lignocellulosic biomass were analyzed. The effects of hydrothermal carbonization were evaluated by varying the reaction temperatures in the range of 180~240 °C. The hydrochars were evaluated with respect to their usefulness as renewable fuels via physicochemical analysis and pyrolysis processes. As reaction temperatures increased, the fractions of fixed carbon in proximate analyses, carbon elements in ultimate analyses, and higher heating values of hydrothermally carbonized biochars increased in correlation with the primary reactions of coalification. Various correlations were derived with the characteristics of hydrochars in order to be utilized for operating and designing HTC reactors for cattle manure. The correlation between the O/C and H/C ratios was deduced on the basis of a van Krevelen diagram. The interaction equation was represented with the increased fraction of HHV compared to the reaction temperature of hydrothermal carbonization. The ultimate correlation for the estimation of higher heating values was suggested for HTC hydrochars. Moreover, the pyrolysis characteristics and kinetic parameters of the cattle manure and hydrochar were deduced by utilizing a multi-step kinetic model scheme. As the HTC reaction temperature increased, the global activation energy and the pre-exponential factors of hydrochars decreased in the low-temperature section and increased in the high-temperature section.
Electric Power Load Forecasting Method Based on a Support Vector Machine Optimized by the Improved Seagull Optimization Algorithm
Authors: Zhang Suqi , Zhang Ningjing , Zhang Ziqi , Chen Ying
Published: December 2022

Accurate load forecasting is conducive to the formulation of the power generation plan, lays the foundation for the formulation of quotation, and provides the basis for the power management system and distribution management system. This study aims to propose a high precision load forecasting method. The power load forecasting model, based on the Improved Seagull Optimization Algorithm, which optimizes SVM (ISOA-SVM), is constructed. First, aiming at the problem that the random selection of internal parameters of SVM will affect its performance, the Improved Seagull Optimization Algorithm (ISOA) is used to optimize its parameters. Second, to solve the slow convergence speed of the Seagull Optimization Algorithm (SOA), three strategies are proposed to improve the optimization performance and convergence accuracy of SOA, and an ISOA algorithm with better optimization performance and higher convergence accuracy is proposed. Finally, the load forecasting model based on ISOA-SVM is established by using the Mean Square Error (MSE) as the objective function. Through the example analysis, the prediction performance of the ISOA-SVM is better than the comparison models and has good prediction accuracy and effectiveness. The more accurate load forecasting can provide guidance for power generation and power consumption planning of the power system.
Optimal Transmission Switching for Short-Circuit Current Limitation Based on Deep Reinforcement Learning
Authors: Tang Sirui , Li Ting , Liu Youbo , Su Yunche , Wang Yunling , Liu Fang , Gao Shuyu
Published: December 2022

The gradual expansion of power transmission networks leads to an increase in short-circuit current (SCC), which has an impact on the secure operation of transmission networks when the SCC exceeds the interrupting capacity of the circuit breakers. In this regard, optimal transmission switching (OTS) is proposed to reduce the short-circuit current while maximizing the loadability with respect to voltage stability. However, the OTS model is a complex combinatorial optimization problem with binary decision variables. To address this problem, this paper employs the deep Q-network (DQN)-based RL algorithm to solve the OTS problem. Case studies on the IEEE 30-bus system and 118-bus system are presented to demonstrate the effectiveness of the proposed method. The numerical results show that the DQN-based agent can select the effective branches at each step and reduce the SCC after implementing the OTS strategies.
Development of a Transient Synchronization Analysis Tool for Line-Start PM Motors
Authors: Schommarz Phillip , Wang Rong-Jie
Published: December 2022

With more stringent IEC energy efficiency standards, electrical machine industry increasingly focuses on new motor technologies. Amongst others, the line-start permanent magnet synchronous machine (LSPMSM) is considered as an attractive alternative to induction machine, especially for low power and fixed-speed applications. However, the design of LSPMSMs is rather complex as both steady-state and transient synchronization performances need to be considered. The synchronization capability determination of a LSPMSM design usually relies on time-consuming transient finite-element simulations, which is impractical for use in an iterative design optimization process. This paper compares and evaluates various existing analytical synchronization analysis methods in an attempt to identify most suitable equations and methods for fast synchronization analysis. Using the selected methods, a software tool is developed that can seamlessly work with ANSYS Electronics Desktop to perform rapid transient synchronization analysis. Given its ability to quickly determine the critical inertia factor of a LSPMSM design, the software tool is further adapted for use in a highly iterative, multi-objective design optimization procedure. It shows that the developed software tool can be successfully used in the design of LSPMSMs.
New Technology of Pressure Relief Control in Soft Coal Roadways with Deep, Violent Mining and Large Deformation: A Key Study
Authors: Xie Shengrong , Li Hui , Chen Dongdong , Feng Shaohua , Ma Xiang , Jiang Zaisheng , Cui Junqi
Published: December 2022

Previous studies have shown that the influence of deep dynamic pressure on the surrounding rock control of a coal roadway is one of the difficulties in mine roadway support. Based on the investigation of the headgate 11231 in a coal mine, this study analyzes the damage characteristics of coal roadway surrounding rock affected by deep dynamic pressure, expounds on the difficulties of controlling the roadway surrounding rock, and creatively proposes a cooperative control technology of external anchor–internal unloading for regulating large deformation of roadways. The vertical stress distribution and transfer law of surrounding rock with different hole-making depths, spacing, and lengths after roadway excavation were simulated and studied, and an appropriate parameter range of hole-making space in the stage without dynamic pressure influence was obtained. Considering the influence of mining dynamic pressure, the surrounding rock pressure relief effect of each optimized hole-making parameter was analyzed. In addition, the optimal hole-making parameters (the hole-making depth, spacing, and length were 8 m, 3.2 m, and 3 m, respectively) that can effectively reduce the high stress of roadway shallow surrounding rock in two stages (without and with dynamic pressure) and ensure integrity of the shallow surrounding rock were obtained. The actual field application shows that the new technology can reduce the higher rib deformation by approximately 850 mm and achieve a good surrounding rock control effect. The research and practice show that the pressure relief control for soft coal roadways with deep, violent mining and large deformation has achieved success, providing technical support for the maintenance of the same type of roadway.
A Review on Segmented Switched Reluctance Motors
Authors: Xu Zhenyao , Li Tao , Zhang Fengge , Zhang Yue , Lee Dong-Hee , Ahn Jin-Woo
Published: December 2022

The switched reluctance motor (SRM) benefits from its magnet-free nature, robust construction, low cost, flexible controls, and the ability to operate in harsh environments such as high temperatures and high pressure. It has received increasing attention for all-electric or multi-electric aircraft systems and electric vehicles (EVs) as compared with permanent magnet synchronous motors (PMSM) and other AC motors in some required high reliability and fault tolerance applications. However, the SRM is prone to considerable wind resistance due to the convex pole structure of the rotor during high-speed rotation, high torque ripple, and also vibration noise. Thus, it is currently a trending topic to develop special SRMs, tailored with high reliability and fault tolerance. Recent research demonstrates several promising feasible solutions to reduce torque ripples and enhance torque density and power factors, including changing topology of SRM, using advanced control methods, as well as different winding configurations. Among these options, the segmented switched reluctance motor (SSRM), as a deformation of the conventional topology, is shown to be capable of effectively optimizing the torque performance. Motivated by this advance, this paper aims to present a comprehensive literature review on the SSRM, first illustrating the development of the topology of the SRM, then providing a description as well as a classification according to the topology of the SSRM. In particular, we focus on the evolution of various kinds of segmental topology and improvement measures. Then, we discuss the performance, advantages, and disadvantages of various types of structures in terms of their electromagnetic aspects and their applications. Eventually, several promising future trends and application prospects of the SSRM are prospected, with the aim of shedding light on further research. In sum, the key contribution of this paper is to provide a valuable basis for detailed analyses of the structure and electromagnetic design of the SSRM that are expected to benefit future research.
Well-Logging Constraints on Gas Hydrate Saturation in Unconsolidated Fine-Grained Reservoirs in the Northern South China Sea
Authors: Wan Xiaoming , Zhou Xueqing , Liang Jinqiang , Wu Shiguo , Lu Jingan , Wei Chenglong , Wang Rui , Liu Bo
Published: December 2022

Recently, drilling wells have encountered rich gas hydrates in fine-grained sediments in the northern South China Sea. Gas hydrate in fine-grained sediments is very heterogeneous, and its physical properties are different from those of oil and gas reservoirs. The reliability of the classical logging saturation evaluation models established for diagenetic reservoirs is questionable. This study used four wells in GMGS3 and GMGS4 to evaluate the effects of the application of three typical methods for evaluating saturation with different principles in the unconsolidated fine-grained sediments: nuclear magnetic logging, sigma logging, and the Archie formula. It was found that the value of the lithologic capture cross-section in sigma logging and the rock’s electrical parameters in the Archie formula affect the accuracy of the model. Therefore, to obtain a reliable saturation value for fine-grained sediments, an innovative method for the calculation of resistivity and acoustic time is proposed to estimate gas hydrate saturation based on logging data, which is most consistent with the results of core analysis. The overall relative error of the verification well was 5.87%, whereas that of the density NMR logging method was 56%, showing that the accuracy of the newly proposed resistivity DT logging method’s saturation formula was significantly improved. Finally, a new model-based cross chart was developed, which can rapidly differentiate gas saturation during drilling.
Application of Renewable Natural Materials for Gas and Water Shutoff Processes in Oil Wells
Authors: Meshalkin Valery , Akhmetov Alfir , Lenchenkova Lyubov , Nzioka Antony , Politov Anatoly , Strizhnev Vladimir , Telin Aleksey , Fakhreeva Alsu
Published: December 2022

We propose a complex sealing compound for increasing the efficiency of shutoff operations based on natural materials processing for materials such as sand, peat, rice, and husks. We studied the influence of mechanical activation processes on the mechanical and rheological properties of the developed sealants. Through mechanochemical activation, sand dissolution in a low-concentrated alkali solution was possible, and gelling the resulting sodium silicate while reinforcing it with undissolved sand particles to obtain a sealant composition. We used this approach to produce a hybrid sealing compound based on activated rice husks with up to 20% biogenic silicon dioxide combined with mechanically activated peat: the maximum shear strain of the hybrid sealant was 27.7 ± 1.7 Pa. We produced hydrogels based on sodium silicate, polyacrylamide, and chromium acetate, reinforced with mechanically activated rice husks. We studied the sealants’ rheological and filtration properties and observed the respective viscoplastic and viscoelastic properties. An increase in the dispersion concentration from 0 to 0.5% increased the maximum strain value of undestroyed hydrogel’s structure in the range 50–91 Pa and the maximum shear strain from 104 to 128 Pa. The high residual resistance factor values of the ideal fracture model make the natural and plant-renewable raw materials very promising for repair and sealing work.
Advanced Study of Spray Cooling: From Theories to Applications
Authors: Zhang Tianshi , Mo Ziming , Xu Xiaoyu , Liu Xiaoyan , Chen Haopeng , Han Zhiwu , Yan Yuying , Jin Yingai
Published: December 2022

With the continuous integration and miniaturization of electronic devices, the heat transfer of the electronic devices continues to surge. This means that thermal management equipment with higher heat flux cooling capacity is required to maintain its normal operation. This paper systematically reviews the progress of spray cooling. In the first part, the thermal dissipation mechanism of spray cooling in the non-boiling regime and boiling regime are summarized, and the correlation formula of heat transfer is summarized. In the second part, the influencing factors of various parameters of the nozzle are summarized, the experimental research and numerical simulation research are summarized separately, and some means and methods to strengthen heat transfer are listed. In the third part, we summarize the current application research of spray cooling in some hot new fields, including electronic technology, aerospace, biomedicine, battery safety, etc. The research prospects and challenges in these fields are highlighted. This research provides a timely and necessary study of spray cooling.
Understanding Species Diversity, Phenology and Environmental Implications of Different Life Forms in Coniferous Forests: A Case Study from Bhallesa Hills of Pir Panjal Mountain, Western Himalaya, India
Authors: Surmal Opender , Singh Bikarma , Musarella Carmelo Maria
Published: December 2022

We assessed, for the first time, the plant assemblages in coniferous forests of temperate and alpine ecosystems of the Himalayas to understand the diversity of species and their phenological behaviours that lead to different growth forms in the climax forest community. In this study, we selected the coniferous forests of Bhallesa Hills, situated in Pir Panjal Mountain (Jammu and Kashmir) of the Himalayan biodiversity hotspot as a study area and used the quadrat method to document the floristic diversity over four years (2018–2021). The study sites were divided into four sub-sites (Chilli, Kahal, Chanwari, Gandoh), and at each site, 25 replicated plots (each measuring 2500 m2, 50 × 50 m2) were established for repeated surveys and documentation. We then analysed species diversity, lifeforms, phenology and leaf size spectra of coniferous plant communities. We consulted various pieces of literature to understand native and non-native plants. The results showed that the species diversity and species richness, growth forms and phenology varied in the experimental plots. In total, we found 328 plant species belonging to 228 genera and 78 families from different localities of various growth forms. Approximately 68.51% of the plant species were native, and 31.49%of the species were non-native. In angiosperms, dicotyledon species were found to be dominant, with 83.23% of the total plant species, while the family Asteraceae was common, with 38 species. The biological spectrum analysis showed 29% of the species were chamaephytes, followed by 28% as therophytes and 21% as phanerophytes. We observed that plant communities respond differently to the existing environment drivers, with chamaephyte and therophytes being more tightly linked to temperate mixed-coniferous and alpine ecosystems, affected by climates and the availability of substrates for their growth and existence. The leaf size spectra analyses showed nanophyll (42.81%) as the dominant group. Conservation-prioritised species (IUCN, regional most threatened species in India), such as Taxus wallichiana Zucc., Picrorhiza kurroa Royle ex Benth., Trillium govanianum Wall. ex D.Don, Aconitum heterophyllum Wall. ex Royle and Euphorbia obovata Decne were found to be the most endangered plants. The results indicated more indigenous species, but there is a slow process of depletion of wild species, leading to colonisation by exotic alien species. This study indicated forests of the Himalayan regions are degrading at a faster rate, species are showing a shift in phenological behaviour due to anthropogenic factors leading to climate change, and indigenous species need conservation measures.
Water in Wood: A Review of Current Understanding and Knowledge Gaps
Authors: Thybring Emil Engelund , Fredriksson Maria , Zelinka Samuel L. , Glass Samuel V.
Published: December 2022

Wood-water interactions are central to the utilization of wood in our society since water affects many important characteristics of wood. This topic has been investigated for more than a century, but new knowledge continues to be generated as a result of improved experimental and computational methods. This review summarizes our current understanding of the fundamentals of water in wood and highlights significant knowledge gaps. Thus, the focus is not only on what is currently known but equally important, what is yet unknown. The review covers locations of water in wood; phase changes and equilibrium states of water in wood; thermodynamics of sorption; terminology including cell wall water (bound water), capillary water (free water), fiber saturation point, and maximum cell wall moisture content; shrinkage and swelling; sorption hysteresis; transport of water in wood; and kinetics of water vapor sorption in the cell wall.
Chances and Limitations of Mixed Oak Regeneration under Continuous Canopy Cover—Evidence from Long-Term Observations
Authors: Stimm Kilian , Uhl Enno , Pretzsch Hans
Published: December 2022

Traditionally, due to its light ecology, oak is regenerated on clear cuts or areas where the crown coverage is heavily reduced. Thus, the regeneration phase is relatively short. Recently, selective long-term regeneration phases avoiding large gaps in the canopy but fostering mixed-species stands have been advocated as being more in keeping with close-to-nature forestry in Central European forests. However, examples of the successful regeneration of oak in mixtures following this type of regeneration are largely missing. Here, we report the results of long-term experiments located in three different forest types, where oak was long-term regenerated under different mixing and canopy cover situations. The observation periods reached from 26 to 36 years. We focused on the dynamics of stem number reduction, as well as the height and biomass development of oaks and their interaction with interspecific competition and canopy density. The probability of oaks occurring in the regeneration basically decreased over the duration of the regeneration period. Despite this, considerable regeneration biomass growth could be observed, especially in the case of the lower standing volume of the mature stand. The development of beech as the main competitor is scarcely slowed down by the canopy cover compared to oak. Increasing canopy cover noticeably impeded oak regeneration in the considered mixed stands. The model results suggest that a reduction in competition within the regeneration by lowering the proportion of beech below 30% enhanced the success of oak regeneration in the long run even in small patches. The productivity of the remaining stand was primarily driven by standing volume. However, a negative trend of its productivity emerged with high regeneration biomasses. The study results show that small-scale oak regeneration with prolonged regeneration duration is possible in principle. However, oak regeneration requires active and continuous silvicultural assistance, which has to be adjusted to the specific site conditions.
Application and Accuracy of Unmanned Aerial Survey Imagery after Salvage Logging in Different Terrain Conditions
Authors: Đuka Andreja , Tomljanović Kristijan , Franjević Milivoj , Janeš David , Žarković Ivan , Papa Ivica
Published: December 2022

The accuracy of the positioning of the data collected by remote sensing platforms is of great importance in forest and wildlife surveys, salvage logging, soil disturbances after felling operations, fire risk management and many other forestry-based research. The significance of bark beetles in silver fir and Norway spruce stands is an essential factor that can affect the increase in biomass quantity and the reduction of its quality. Due to an Ips typographus (L.) outbreaks in the central part of Croatia from 2016 to 2021, salvage logging was performed in an area of 11,940 ha, with terrain slopes varying from 0 to 172.83%. Two plots of similar sizes (<5 ha) and different terrain conditions (flat vs. sloped terrain) were chosen and were measured in June 2022. Measurements included a total station, a real-time kinematic (RTK) GNSS (Global Navigation Satellite System) terrestrial receiver and an unmanned aerial system (UAS) in order to determine the accuracy of a digital terrain model (DEM) generated by a photogrammetric UAS. In total, 175 checkpoints were marked in the field. Four different GCP (Ground Control Point) classes (5, 10, 15 and 20) were used to compare validation points acquired from the original point clouds, imagery and orthophotos to the reference positions. This study showed that, in terms of a forest area recognition after conducted salvage logging, the use of 10 GCPs for terrain evaluation is necessary even in small areas below 5 ha and regardless of terrain slope.