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Salinity is an essential parameter for evaluating water quality and plays a crucial role in maintaining the stability of lake ecosystems, particularly in arid and semi-arid climates. Salinity responds to changes in climate and human activity, with significant impacts on water quality and ecosystem services. In this study, Sentinel-2A/B Multi-Spectral Instrument (MSI) images and quasi-synchronous field data were utilized to estimate lake salinity using machine learning approaches (i.e., XGB, CNN, DNN, and RFR). Atmospheric correction for MSI images was tested using six processors (ACOLITE, C2RCC, POLYMER, MUMM, iCOR, and Sen2Cor). The most accurate model and atmospheric correction method were found to be the extreme gradient boosting tree combined with the ACOLITE correction algorithm. These were used to develop a salinity model (N = 70, mean absolute percentage error = 9.95%) and applied to eight lakes in Inner Mongolia from 2016 to 2024. Seasonal and interannual variations were explored, along with an examination of potential drivers of salinity changes over time. Average salinities in the autumn and spring were higher than in the summer. The highest salinities were observed in the lake centers and tended to be consistent and homogeneous. Interannual trends in salinity were evident in several lakes, influenced by evaporation and precipitation. Climate factors were the primary drivers of interannual salinity trends in most lakes. [ABSTRACT FROM AUTHOR]

Pumped storage units serve as a crucial support for power systems to adapt to large-scale and high-proportion renewable energy sources by providing a stable and flexible energy supply. However, due to the coupling effects of electric power load demands and the complex multi-source factors within the water–mechanical–electrical system, the interrelationship between unit parameters becomes more intricate, posing significant threats to the operational reliability and health status of the units. The complexity of fault diagnosis is further aggravated by the intricate and varied nature of fault characteristics, as well as the challenges in signal extraction under conditions of strong electromagnetic interference and high noise levels. To address these issues, this paper proposes a novel data-model hybrid-driven strategy that analyzes vibration signals to achieve rapid and accurate fault diagnosis of the units. Firstly, the spectral kurtosis theory is employed to enhance the traditional empirical mode decomposition, achieving optimal decomposition and noise reduction effects for vibration signals. Secondly, the intrinsic mode functions (IMFs) obtained from the decomposition are reconstructed, and the entropy values of effective IMFs are calculated as fault feature vectors. Subsequently, the CNN-LSTM model is utilized for fault diagnosis. The effectiveness and feasibility of the proposed method are verified through actual operational data from pumped storage units in a specific region. Through analysis, the fault diagnosis accuracy of the method proposed in this paper can be maintained above 95%, demonstrating robustness in complex engineering environments and effectively ensuring the safe and stable operation of pumped storage units. [ABSTRACT FROM AUTHOR]

In technology and industrial production, many applications require wide-bandwidth current measurements. In this paper, a signal fusion scheme for a current sensor comprising tunneling magnetoresistance and a current transformer is proposed, achieving a flat frequency response in the DC to MHz range. The measurement principles in different cases of the scheme are introduced, and the total transfer function of the entire scheme is derived by analyzing each section separately. Furthermore, the feasibility and selected parameters of the scheme are verified through a systematic simulation utilizing the MATLAB software. Based on the proposed scheme, a group of principal prototypes are built to experimentally evaluate the bandwidth, amplitude and phase flatness, accuracy, sensitivity, and impulse response. The relative amplitude variation in the passband of the fusion sensor is less than 4%, and the estimated bandwidth of the fusion sensor is close to 17 MHz. The accuracy is better than 0.6%, even when measuring the current at 1 MHz, and the relative standard deviation is 5% when measuring the impulse signal. The sensors developed using this scheme, with a low financial cost, have advantages in many wide-bandwidth current measuring scenarios. [ABSTRACT FROM AUTHOR]

Group B Coxsackieviruses (CVB) are one of the causative pathogens of myocarditis, which may progress to cardiomyopathy. The pathogenesis of CVB is not fully understood, and effective antiviral therapy is not available. N-acetylcysteine (NAC), the classic antioxidant, has been used in clinical practice for several decades to treat various medical conditions. In this study, the anti-CVB effect of NAC was investigated. We show that NAC dramatically suppressed viral replication and alleviated cardiac injury induced by CVB3. To further study the antiviral mechanism of NAC, RNA-sequencing was performed for CVB3-infected cells with NAC treatment. We found that eukaryotic elongation factor 1 alpha 1 (EEF1A1) is one of the most upregulated genes in CVB3-infected cells. However, EEF1A2, the highly homologous isoform of EEF1A1, remains unchanged. EEF1A1 expression was significantly suppressed by NAC treatment in CVB3-infected cells, while EEF1A2 was not affected. eEF1A1 knockdown significantly inhibited CVB3 replication, implicating that eEF1A1 facilitates viral replication. Importantly, we show that eEF1A1, which was not expressed in the myocardia of newborn mice, was significantly upregulated by CVB3 infection. NAC markedly downregulated the expression of eEF1A1 but not eEF1A2 in the myocardia of CVB3-infected mice. Furthermore, NAC accelerated eEF1A1 degradation by promoting autophagy in CVB3-infected cells. We show that p62, one of the critical adaptors of autophagic targets, interacts with eEF1A1 and was downregulated in CVB3-infected cells upon NAC treatment. Taken together, this study demonstrated that NAC shows a potent anti-CVB effect through the downregulation of eEF1A1. [ABSTRACT FROM AUTHOR]

A key research focus at present is the exploration and innovation of electrode materials suitable for energy storage and conversion. Molybdenum-based sulfides/selenides (primarily MoS2 and MoSe2) have garnered attention in recent years due to their intrinsic two-dimensional structures, which are conducive to ion/electron transfer or insertion/extraction, making them promising candidates in electrocatalytic hydrogen production and sodium-ion battery applications. However, their inherently poor electronic structures have led most research efforts to concentrate on modifications aimed at enhancing their performance in hydrogen evolution reactions (HERs) and sodium-ion batteries (SIBs). Owing to their remarkable chemical inertness, expansive specific surface areas, and tunable pore architectures, carbon-based materials have garnered significant attention in research. The utilization of biomass as a renewable and environmentally sustainable precursor offers considerable benefits, including abundant availability, ecological compatibility, and cost-effectiveness. Consequently, recent scholarly endeavors have concentrated intensively on the synthesis of valuable carbon materials derived from renewable biomass sources. This review addresses the scientific challenges related to the development of electrode materials for HERs and SIBs in electrochemical energy storage and conversion. It delves into the recent focus on the two-dimensional transition-metal chalcogenides, particularly MoS2 and MoSe2, and the difficulties encountered in modulating their electronic structures when applied to HERs and SIBs. The review proposes the use of eco-friendly and widely sourced biomass-derived carbon (BMC) as a supporting matrix combined with MoS2 and MoSe2 to regulate their structures and enhance their electrocatalytic activity and sodium storage performance. Additionally, it highlights the existing challenges faced by these BMC/MoS2 and BMC/MoSe2 composites and offers insights into future developments. [ABSTRACT FROM AUTHOR]

In the past three decades, stepping-stone intrusion has become a professional and primary way used by intruders to launch their attacks since they can be protected behind a long TCP connection chain. Many different algorithms have been proposed to detect stepping-stone intrusion since 1995. But most algorithms cannot resist intruders' session manipulation. In this paper, we propose a novel approach using the distribution of round-trip time (RTT) of network traffic to detect stepping-stone intrusion. This approach can resist intruders' chaff-perturbation since the round-trip time of network packets can fairly be affected by chaffed packets. The ratio between the standard deviation of the RTTs between Send and Echo packets and the standard deviation of the RTTs between Send and Ack packets can be used to predict if a stepping-stone intrusion exists. The closer to 0 the ratio, the more suspicious a stepping-stone intrusion. [ABSTRACT FROM AUTHOR]

Cities are complex systems influenced by a multitude of factors, encompassing society, economy, culture, and environment. These factors make urban development highly vulnerable to various disturbances. Communities work as the fundamental building blocks of a city and directly impact both its social structure and spatial layout. Moreover, urban planning and policies play a crucial role in shaping the development trajectory of communities and the living environment for residents. This study aims to develop a Bayesian and analytic hierarchy process (BAHP)-based multilevel community resilience evaluation method to assess the ability of the community system to withstand disturbances and recover from them. First, the proposed method establishes a comprehensive assessment index system that can evaluate social and environmental resilience as well as institutional and managerial resilience at multiple levels. This system serves as a quantitative decision-making tool to elucidate the impact of various factors on community resilience. Furthermore, the "relative demand coefficient" (RDC) is proposed to compare different communities' resilience by using Bayesian inference to determine its most probable value (MPV). To validate the applicability of the proposed method, an empirical study was conducted in the Dafapu community located in the Longgang District of Shenzhen. Meanwhile, a simulated virtual community is employed for comparison with the Dafapu community as an illustrative example showcasing the proposed method's superior performance after integrating the RDC. The empirical study demonstrates that the proposed BAHP-based method can effectively and quantitatively highlight the recovery capabilities and limitations for different communities in various dimensions while providing a clear direction for enhancing urban community resilience. This research contributes new insights to the theory, provides a practical tool to quantify community resilience, and offers a viable path for the actual enhancement of community resilience. [ABSTRACT FROM AUTHOR]

This paper presents a charge pump circuit with a wide output range and low current mismatch applied to phase-locked loops. In this designed structure, T-shaped analog switches are adopted to suppress the non-ideal effects of clock feedthrough, switching time mismatch, and charge injection. A source follower and current splitting circuits are proposed to improve the matching accuracy of the charging and discharging currents and reduce the current mismatch rate. A rail-to-rail high-gain amplifier with a negative feedback connection is introduced to suppress the charge-sharing effect of the charge pump. A cascode current mirror with a high output impedance is used to provide the charge and discharge currents for the charge pump, which not only improves the current accuracy of the charge pump but also increases the output voltage range. The proposed charge pump is designed and simulated based on a 65 nm CMOS process. The results show that when the power supply voltage is 1.2 V, the output current of the charge pump is 100 μA, the output voltage is in the range of 0.2~1 V, and the maximum current mismatch rate and current variation rate are only 0.21% and 1.4%, respectively. [ABSTRACT FROM AUTHOR]

The lack of efficient and non-precious metal catalysts poses a challenge for electrochemical water splitting in hydrogen and oxygen evolution reactions. Here, we report on the preparation of growing Ni(OH)2 nanosheets in situ on a Ni and graphene hybrid using supergravity electrodeposition and the hydrothermal method. The obtained catalyst displays outstanding performance with small overpotentials of 161.7 and 41 mV to acquire current densities of 100 and 10 mA cm−2 on hydrogen evolution reaction, overpotentials of 407 and 331 mV to afford 100 and 50 mA cm−2 on oxygen evolution reaction, and 10 mA·cm−2 at a cell voltage of 1.43 V for water splitting in 1 M KOH. The electrochemical activity of the catalyst is higher than most of the earth-abundant materials reported to date, which is mainly due to its special hierarchical structure, large surface area, and good electrical conductivity. This study provides new tactics for enhancing the catalytic performance of water electrolysis. [ABSTRACT FROM AUTHOR]

Flight control law parameters should be designed to provide a sufficient stability margin for closed-loop aircraft while ensuring command tracking accuracy. The singular perturbation margin (SPM) and generalized gain margin (GGM), which are generalizations of the classical phase margin (PM) and gain margin (GM), respectively, from a linear time-invariant system to a nonlinear time-varying system, can be used to quantitatively characterize the maximum singular perturbation and regular perturbation allowed to maintain system stability. In this paper, the sliding mode flight control structure and the design parameters of the sliding mode control law are first introduced for an oblique wing aircraft (OWA), the SPM-gauge and GGM-gauge are added to this closed-loop aircraft model, and the analytical expressions of the SPM and GGM are derived with respect to the control law parameters. Second, the stability margin design requirements of closed-loop aircraft in flight control system design specifications are converted into limitations on the SPM and GGM to determine the value range of the flight control law parameters. Then, with the goal of reducing the sum of the approaching time and sliding time, the parameter value combination is selected within the control law parameter range that meets the stability margin requirements, thus forming a flight control law design method for OWA during the wing skewing process. Finally, the designed control law parameters are applied to a sample OWA, and the stability margin of closed-loop aircraft during the wing skewing process is verified. [ABSTRACT FROM AUTHOR]

The decrease in lake area has garnered significant attention within the global ecological community, prompting extensive research in remote sensing and computer vision to accurately segment lake areas from satellite images. However, existing image segmentation models suffer from poor generalization performance, the imprecise depiction of water body edges, and the inadequate inclusion of water body segmentation information. To address these limitations and improve the accuracy of water body segmentation in remote sensing images, we propose a novel GEA-MSNet segmentation model. Our model incorporates a global efficient attention module (GEA) and multi-scale feature fusion to enhance the precision of water body delineation. By emphasizing global semantic information, our GEA-MSNet effectively learns image features from remote sensing data, enabling the accurate detection and segmentation of water bodies. This study makes three key contributions: firstly, we introduce the GEA module within the encode framework to aggregate shallow feature semantics for the improved classification accuracy of lake pixels; secondly, we employ a multi-scale feature fusion structure during decoding to expand the acceptance domain for feature extraction while prioritizing water body features in images; thirdly, extensive experiments are conducted on both scene classification datasets and Tibetan Plateau lake datasets with ablation experiments validating the effectiveness of our proposed GEA module and multi-scale feature fusion structure. Ultimately, our GEA-MSNet model demonstrates exceptional performance across multiple datasets with an average intersection ratio union (mIoU) improved to 75.49%, recall enhanced to 83.79%, pixel accuracy (PA) reaching 90.21%, and the f1-score significantly elevated to 83.25%. [ABSTRACT FROM AUTHOR]

As a critical raw material for the textile industry, cotton lint provides various types of cotton yarns, fabrics and finished products. However, due to the complexity of the supply chain and its many links, information records are often missing, inaccurate or lagging, resulting in low transparency and traceability. In the traditional cotton lint supply chain, the data of each link are stored in isolation; due to the lack of an effective sharing mechanism and the formation of "information silos", complete traceability is challenging to achieve. In addition, the completeness and authenticity of documents such as lint quality reports and certificates of origin must be rapidly strengthened. Otherwise, quality problems may arise. To solve the above problems, this study proposes a cotton lint supply chain traceability system based on blockchain and non-fungible tokens (NFTs), covering the whole cotton lint production process from harvesting to selling. We use an NFT as an asset token to digitise seed cotton, cotton lint and quality inspection reports and allow participants to store and manage these assets on the blockchain. The system design includes architecture diagrams, sequence diagrams and Ethernet smart contract development based on the ERC721 standard. In addition, the integration of Interplanetary File System (IPFS) technology solves the problem of storing large files on the chain and ensures that the data are permanently preserved and cannot be tampered with. We provide a diagram of the interactions between the system components and the four core algorithms' design, testing and verification process. We present an in-depth analysis of the solution regarding the transaction costs and smart contract security. We confirm the solution's security, reliability and applicability through a cost evaluation and security analysis. [ABSTRACT FROM AUTHOR]

For covert communication in lossy channels, it is necessary to consider that the carrier of the hidden watermark will undergo multiple image-processing attacks. In order to ensure that secret information can be extracted without distortion from the watermarked images that have undergone attacks, in this paper, we design a novel fragmented secure communication system. The sender will fragment the secret data to be transmitted and redundantly hide it in a large number of multimodal carriers of messenger accounts on multiple social platforms. The receiver receives enough covert carriers, extracts each fragment, and concatenates the transmitted secret data. This article uses the image carrier as an example to fragment the text file intended for transmission and embeds it into a large number of images, with each fragment being redundant and embedded into multiple images. In this way, at the receiving end, only enough stego images need to be received to extract the information in each image, and then concatenate the final secret file. In order to resist various possible attacks during image transmission, we propose a strong robust image watermarking method. This method adopts a watermark layer based on DFT, which has high embedding and detection efficiency and good invisibility. Secondly, a watermark layer based on DCT is adopted, which can resist translation attacks, JPEG attacks, and other common attacks. Experiments have shown that our watermarking method is very fast; both the embedding time and the extraction time are less than 0.15 s for images not larger than 2000 × 2000 . Our watermarking method has very good invisibility with 41 dB PSNR on average. And our watermarking method is more robust than existing schemes and robust to nearly all kinds of attacks. Based on this strong robust image watermarking method, the scheme of fragmenting and hiding redundant transmission content into a large number of images is effective and practical. Our scheme can 100% restore the secret file completely under different RST or hybrid attacks, such as rotation by 1 degree and 5 degrees, scaling by 1.25 and 0.8, and cropping by 10% and 25%. Our scheme can successfully restore the secret file completely even if 30% of received images are lost. When 80% of received images are lost, our scheme can still restore 61.1% of the secret file. If all stego images can be obtained, the original text file can be completely restored. [ABSTRACT FROM AUTHOR]

Wire and cable are important industrial products involving the national economy and people's livelihood, which are hailed as the "blood vessel" and "nerve" of the national economy, providing the basic guarantee for the normal operation of modern economy and society. The data traceability of their production and circulation process is a key factor in ensuring their quality and safety management. We aim to solve the problems of unsafe data transmission, weak quality control, and information islands in the process of wire and cable quality traceability in order to improve the production management efficiency of wire and cable manufacturing enterprises and to reduce the cost of consumer quality traceability of wire and cable products. We analyzed the technical characteristics and advantages of Industrial Internet of Things (IIoT) identity resolution and the blockchain. Key technologies are introduced, a traceability method that integrates the two is proposed, and a quality traceability framework based on the IIoT identity resolution system and blockchain technology is constructed. By analyzing the quality information composition of the wire and cable supply chain, a new quality traceability model based on the wire and cable supply chain is established. Finally, through the verification of the developed quality traceability system, the quality traceability function and quality information of each production link of wire and cable are successfully realized. This paper fills a gap in the field of cable product quality traceability using the combination of IIoT and blockchain technology. According to this model, it also has some potential for the traceability of other industrial products. [ABSTRACT FROM AUTHOR]

The upset state is an unexpected flight state, which is characterized by an unintentional deviation from normal operating parameters. It is difficult for the pilot to recover the aircraft from the upset state accurately and quickly. In this paper, an upset recovery strategy and pilot assistance system (PAS) based on reinforcement learning is proposed. The man–machine closed-loop system was established and the upset state, such as a high angle of attack and large attitude angle, was induced. The upset recovery problem was transformed into a sequential decision problem, and the Markov decision model of upset recovery was established by taking the deflection change of the control surface as the action. The proximal policy optimization (PPO) algorithm was selected for the strategy training. The adaptive pilot model and the reinforcement learning method proposed in this paper were used to make the aircraft recover from the upset state. Based on the correspondence between the flight state, the recovery method, and the recovery result, the aircraft upset recovery safety envelopes were formed, and the four-level upset recovery PAS with alarm warning, coordinated control, and autonomous recovery modes was constructed. The results of the digital virtual flight simulation and ground flight test show that compared with a traditional single pilot, the aircraft upset recovery strategy, the upset recovery safety envelopes, and the PAS established in this study could reduce the handling burden of the pilot and improve the success rate and effect of upset recovery. This research has certain theoretical reference values for flight safety and pilot training. [ABSTRACT FROM AUTHOR]

As urbanization accelerates, deep excavation projects have become increasingly vital in the construction of high-rise buildings and underground facilities. However, the potential risks to the surrounding environment and the inherent complexities involved necessitate thorough research to ensure the safety of those engineering projects with deep foundation pit excavation and to minimize their impact on adjacent structures. This study introduces a multi-stage and multi-parameter numerical simulation method to scrutinize the construction process of deep foundation pits. This approach not only investigates the influence of excavation activities on nearby buildings and roads but also enhances the fidelity of simulation models by establishing a three-dimensional finite element model integrated with on-site investigated geological information. Therefore, the proposed method can provide a more holistic and accurate analysis of the overall impacts of the pit excavation process. To examine the feasibility and effectiveness of the proposed method, this study adopts the multi-stage and multi-parameter influence analysis approach for a real practical engineering case to explore the impact of excavation on the foundation pit support structure, nearby buildings, and surrounding roads. The foundation pit support's maximum displacement was 8.64 mm, well under the 25 mm standard limit. Anchor rod forces were about 10% below the standard limit. Building and road settlements were also minimal, at 10.33 mm and 16.44 mm, respectively, far below their respective limits of 200 mm and 300 mm. This study not only validates the feasibility of design and construction stability of deep foundation pits but also contributes theoretical and practical insights, serving as a valuable reference for future engineering projects of a similar scope. [ABSTRACT FROM AUTHOR]

This paper presents a high-speed level shifter with about 500 V/ns power supply slew immunity. In this designed structure, a narrow pulse-controlled current source is adapted to accelerate the voltage conversion and reduce the power consumption. A Fast-Slewing Circuit speeds up the operation of the level shifter based on the current comparison principle. Edge detection technology is used to filter the generated voltage noise and achieve high dV/dt immunity. The proposed level shifter simulated with the 0.18 μm BCD (bipolar-CMOS-DMOS) process shows fast responses with a typical delay of 1.49 ns and 500 V/ns dV/dt immunity in the 200 V high-voltage application, which only occupies a 0.022 mm2 active area with the 0.18 μm BCD process. [ABSTRACT FROM AUTHOR]

Advanced composite materials have excellent performance and broad engineering application prospects, and have received widespread attention in recent years. Advanced composite materials can mainly be divided into fiber-reinforced composite materials, laminated composite materials, matrix composite materials, and other composite materials. This article provides a comprehensive overview of the types and characteristics of advanced composite materials, and provides a comprehensive evaluation of the latest research on structural strengthening and resilience improvement in advanced composite materials from the perspectives of new methods, modeling optimization, and practical applications. In the field of fiber-reinforced composite materials, the hybrid technology of carbon fiber and glass fiber can achieve dual advantages in combining the two materials. The maximum increase in mechanical properties of multilayer sandwich RH plate by hybrid technology is 435.4% (tensile strength), 149.2% (flexural strength), and 110.7~114.2% (shear strength), respectively. In the field of laminated composite materials, different mechanical properties of laminated composite materials can be obtained by changing the deposition sequence. In the field of matrix composites, nano copper oxide particles prepared by nanotechnology can increase the hardness and tensile strength of the metal matrix material by 77% and 78%, respectively. In the field of other composite materials, viscoelastic materials and magnetorheological variants have received widespread attention. The development of composite materials benefits from the promotion of new methods and technologies, but there are still problems such as complex preparation, high cost, and unstable performance. Considering the characteristics, application requirements, cost, complexity, and performance of different types of composite materials, further improvements and innovations are needed in modeling and optimization to better meet practical engineering needs, such as the application of advanced composite materials in civil engineering, ships, automobiles, batteries, and other fields. [ABSTRACT FROM AUTHOR]

Today's intruders usually send attacking commands to a target system through several stepping-stone hosts, for the purpose of decreasing the probability of being caught. Using stepping-stone intrusion (SSI), the intruder's identity is very difficult to discover as it is concealed by a long interactive connection chain of hosts. An effective approach for SSI detection (SSID) is to determine how many connections are contained in a connection chain. This type of method is called network-based SSID. Most existing network-based SSID only worked for network traffic without intruders' session manipulation. These known SSID algorithms are either weak to resist intruders' chaff-perturbation manipulation or have very limited capability in resisting attacker's session manipulation. This paper develops a novel network-based SSID algorithm resistant to intruders' chaff-perturbation by using packet crossover. The SSID approach proposed in this paper is simple and easy to implement as the number of packet crossovers can be easily computed. Our proposed algorithm is verified by rigorous technical proofs as well as well-designed network experiments. Our experimental results show that the proposed SSID algorithm works effectively and perfectly in resisting intruders' chaff-perturbation up to a chaff rate of 50%. [ABSTRACT FROM AUTHOR]

Ternary transition metal phosphides (TTMPs) with two-dimensional heterointerface and adjustable electronic structures have been widely studied in hydrogen evolution reactions (HER). However, single-phase TMPs often have inappropriate H* adsorption energy and electronic transfer efficiency in HER. Herein, we utilized the heterogeneity in the crystal structure to design an efficient and stable catalyst from the NiCoP nanowire@NiCoP nanosheet on nickel foam (NW-NiCoP@NS-NiCoP/NF) for HER. Layered double hydroxides (LDHs) with a heterogeneous matrix on crystal surfaces were grown under different reaction conditions, and non-metallic P was introduced by anion exchange to adjust the electronic structure of the transition metals. The hierarchical structure of homologous NiCoP/NF from the LDH allows for a larger surface area, which results in more active sites and improved gas diffusion. The optimized NW-NiCoP@NS-NiCoP/NF electrode exhibits excellent HER activity, with an overpotential of 144 mV, a Tafel slope of 84.2 mV dec−1 at a current density of 100 mA cm−2 and remarkable stability for more than 500 h in 1.0 M KOH electrolyte. This work provides ideas for elucidating the rational design of structural heterogeneity as an efficient electrocatalyst and the in situ construction of hierarchical structures. [ABSTRACT FROM AUTHOR]

Using a nonlinear pilot-induced oscillation prediction method based on digital virtual flight simulation calculations, digital experiments on predicting lateral-directional nonlinear pilot-induced oscillations due to landing configuration switching of fly-by-wire civil aircraft with different closed-loop dynamic characteristics are carried out. It is proposed that the lateral-directional pilot-induced oscillations due to the landing configuration switch can be evaluated using the changes in dynamic characteristic parameters before and after the configuration switch. The quantitative boundaries of the dynamic characteristic parameters of an example aircraft are determined, and a criterion suggestion is formed to predict the lateral-directional nonlinear pilot-induced oscillations due to landing configuration switching. This study provides a reference for the optimal design of the lateral-directional flight control law of fly-by-wire aircraft during the approach stage and provides suggestions for the formulation of evaluation criteria for other nonlinear pilot-induced oscillation phenomena. [ABSTRACT FROM AUTHOR]

In numerous subterranean projects, the impact of groundwater on the safety of the engineering undertaking is of paramount significance. Fractures, functioning as the primary channels for seepage within subterranean rock masses, necessitate the complex and challenging task of accurately characterizing seepage patterns and quantitatively investigating the effect of fissure parameters on fluid dynamics within the rock masses. This article presents a stochastic fissure model incorporated within a finite element framework, which captures the probabilistic distribution of fissures found in nature. It provides a comprehensive analysis of the distribution of pore water pressure and Darcy velocity fields. It unveils the permeation patterns of fissured rock masses and establishes a series of fissure models, quantitatively investigating the correlations between matrix permeability, water pressure, fissure density, fissure length, the length power law, fissure angle, the dispersion coefficient, fissure aperture, and the aperture power law, as well as their influence on the equivalent permeability of the rock mass. The findings reveal that in a discrete fissured rock mass, the greater the matrix permeability, the higher the equivalent permeability, and vice versa. Under water pressures of less than 10 MPa, gravity significantly impacts equivalent permeability, and permeability linearly increases with a rise in fissure density. Longer fractures result in higher permeability, and fractures parallel to the direction of water pressure contribute most significantly to the speed of seepage. Moreover, permeability markedly increases with an increase in aperture. This study provides a comprehensive analysis of the impact of matrix permeability and fissure parameters on equivalent permeability and calculates the permeability of each model. We also propose a set of predictive formulas based on fissure geometric parameters to anticipate the permeability of rock masses. [ABSTRACT FROM AUTHOR]

Environmental change is a crucial driver shaping grassland biodiversity and stability. Both environmental change and stability contain multiple dimensions. Nonetheless, few studies examined multiple dimensions of stability in response to environmental change, especially under the combined effects of climatic variability and grazing intensity. Here, we conducted a 7-year field sheep grazing experiment, and we evaluated the impacts of grazing intensity (GI) and climate variability (temperature and precipitation variability) on plant community diversity and productivity and multi-dimensional stability using linear and structural equation models. Our results show that increasing grazing intensity significantly decreased temporal stability but did not affect resistance stability. Compared with the non-grazing (NG) treatment, grazing reduced temporal stability by 35.78%. The decline is primarily attributed to the grazing-induced reduction in evenness and weakening of species asynchrony, which in turn impairs insurance effects. The insignificant change in resistance stability was attributed to a trade-off between reduced interspecific competition and direct negative effects. Furthermore, temperature variability and precipitation variability exacerbate and mitigate the effects of grazing on temporal stability (negative) and resistance stability (positive), respectively. Overall, temporal stability is mainly influenced by temperature variability and GI, while resistance stability is mainly affected by GI. Our findings highlight the importance of considering the dimensions of stability and disturbance. Different dimensions of stability may respond differently to disturbance. Multiple disturbances may also interact synergistically or antagonistically on plant community stability. [ABSTRACT FROM AUTHOR]

The safety of underground engineering projects is significantly influenced by groundwater. One of the key complexities is identifying the primary seepage paths within underground rock formations, understanding the patterns of seepage, and determining the effects of fracture parameters on the fluid movement inside the rock mass. To address these issues, a probabilistic model is constructed for random fractures using the finite element method, reflecting the random nature of fracture distributions in the real world. This model allows for an in-depth examination of the distribution of pore water pressure and Darcy velocity field, revealing the permeability trends in fractured rock masses. A variety of fracture models were devised to understand the relationship between factors such as fracture density, length, length power law, angle, dispersion coefficient, aperture, and power law, and how they affect the overall permeability of rock masses. The study suggests that, in the context of discrete fractured rock masses, there is a linear increase in permeability with an increase in fracture density and aperture. Moreover, fractures of greater length lead to increased permeability, with fractures aligned with the direction of water pressure having the most impact on seepage velocity. A thorough investigation of the factors that affect each fracture parameter was performed, and the permeability of each model was computed. From these findings, a series of predictive equations were suggested for estimating rock permeability based on fracture geometry parameters. [ABSTRACT FROM AUTHOR]

The current research into decision-making strategies for air combat focuses on the performance of algorithms, while the selection of actions is often ignored, and the actions are often fixed in amplitude and limited in number in order to improve the convergence efficiency, making the strategy unable to give full play to the maneuverability of the aircraft. In this paper, a decision-making strategy for close-range air combat based on reinforcement learning with variable-scale actions is proposed; the actions are the variable-scale virtual pursuit angles and speeds. Firstly, a trajectory prediction method consisting of a real-time prediction, correction, and judgment of errors is proposed. The back propagation (BP) neural network and the long and short term memory (LSTM) neural network are used as base prediction network and correction prediction network, respectively. Secondly, the past, current, and future positions of the target aircraft are used as virtual pursuit points, and they are converted into virtual pursuit angles as the track angle commands using angle guidance law. Then, the proximity policy optimization (PPO) algorithm is applied to train the agent. The simulation results show that the attacking aircraft that uses the strategy proposed in this paper has a higher win rate during air combat and the attacking aircraft's maneuverability is fully utilized. [ABSTRACT FROM AUTHOR]

This study aimed to analyze the spatial distribution of soil organic carbon (SOC) and total nitrogen (STN) in a micro-catchment area comprising farmland and a gully with vegetation restoration (artificial forest and grassland) and their influencing factors. We surveyed a total of 52 topsoil sampling sites to measure the SOC and STN content, as well as topographical factors (elevation, curvature, slope gradient, and aspect), soil properties (bulk density, aggregate distribution, soil texture, and soil moisture), and land use and management. We used traditional statistical and geostatistical methods to analyze the spatial variability of SOC and STN. The results of this study indicate that SOC and STN content varied moderately across the entire micro-catchment area, with greater values in the west (gully head area) than in the east (gully mouth area). Additionally, SOC and STN were significantly positively correlated with soil water content, >2 mm size aggregate fraction, and elevation, but negatively correlated with <0.053 mm size fraction. Land use types also influenced the spatial distribution of SOC and STN contents, with the highest averages of SOC and STN content found at the edge of farmland road and grassland, respectively, and the lowest values in bare land. This study provides a valuable supplement to the understanding of SOC and STN in micro-catchment areas, and the research results also support the evaluation of the impact of gully erosion control on SOC and STN dynamics after vegetation restoration. Overall, vegetation restoration should be adopted for gully erosion control and sustainable agricultural development in the Mollisols region of Northeast China. [ABSTRACT FROM AUTHOR]

This paper is concerned with calculating the phase stability of a phase stable cable with multi-physics coupling simulations. A three-dimensional electromagnetic-thermal-flow-mechanics multi-physics coupling model is established to simulate the phase stable cable operating in air. The simulation results demonstrate that the electric field distribution of the corrugated cable shows differences from that of a normal coaxial cable around the outer conductor, i.e., the electric field is stronger around the sharp points of the outer conductor than the blunt points, which elevates the voltage endurance requirement of the cable and the risk of breakdown during the transmission of high power. Regarding the thermal deformation, simulations reveal that the corrugated outer conductor restrains the insulation from expanding along both the cross-section direction and the axial direction, and the thermal expansion might be manipulated through the proper design of the outer conductor parameters. Finally, the consistency between the simulated and measured results of phase stability witnesses the validity of the multi-physics coupling model, and its accuracy might be refined with more precise material properties. [ABSTRACT FROM AUTHOR]

In the early stages of aircraft design, a scaled model of the aircraft is installed in a wind tunnel for dynamic semi-free flight to approximate real flight, and the test data are then used to identify the aerodynamic parameters. However, the absence of the translational motion of the test model makes its flight dynamics different from those in free flight, and the effect of this difference on parameter identification needs to be investigated. To solve this problem, a 3-DOF wind tunnel virtual flight test device is built to fix the test model on a rotating mechanism, and the model is free to rotate in three axes through the deflection of the control surfaces. The flight dynamics equations for the wind tunnel virtual flight test are established and expressed as a decoupled form of the free flight force and the influence of the test support frame force on the model's motions through linearization. The differences between wind tunnel virtual flight and free flight are analysed to develop a model for the identification of aerodynamic parameters. The selection of the lateral-directional excitation signal and the design method of its parameters are established based on the requirements for the identifiability of the aerodynamic derivatives, and a step-by-step method for the identification of aerodynamic force and moment derivatives is established. The aerodynamic parameter identification results of a blended wing body aircraft show that the identification method proposed in this paper can obtain results with high accuracy, and the response of the modified motion model is consistent with that of the free flight motion model. [ABSTRACT FROM AUTHOR]

The stall aerodynamic model based on Kirchhoff's theory of flow separation is widely used in the identification and modeling of stall aerodynamic parameters. However, it has two defects. First, its model structure is significantly different from the pre-stall model used for a small attack angle, meaning the identification results cannot be combined with the pre-stall model to form the full flight envelope model. Second, the pitching moment model, which is used in conjunction with the Kirchhoff lift model, cannot accurately describe the aircraft stall pitching moment characteristics. To ensure the compatibility of the two models, this paper proposes a method to determine some unknown parameters in the stall model. The mechanism for the pitching moment generation of the aircraft stall is analyzed, and two high-order correction terms are added to the pitching moment model to better describe the longitudinal stall aerodynamic characteristics. Based on the identification of aerodynamic parameters, a longitudinal stall aerodynamic modeling method used for the aircraft stall process is developed. The identification and simulation validation results based on the quasi-steady stall flight data of a civil aircraft show that the improved stall model can accurately describe the quasi-steady stall pitching moment. The established stall aerodynamic model can accurately characterize the longitudinal quasi-steady stall aerodynamic characteristics of aircraft under different stall degrees. [ABSTRACT FROM AUTHOR]

An output-capacitorless low-dropout regulator (LDO) with a push–pull buffer was presented in this paper. The proposed push–pull buffer was able to provide a large charge and discharge current to increase the slew rate at the gate of the power transistor effectively, thereby improving the transient response of this LDO. In addition, an adaptive resistance unit (ARU) was proposed to solve the right half-plane zero problem caused by Miller compensation to optimize the loop stability of the LDO. The proposed LDO was implemented in a 0.18-µm CMOS technology. Simulation results showed that the quiescent current of this LDO was only 16.1 µA. It regulated the output at 1.5 V from a 1.8 V supply, with a dropout voltage of 300 mV at the maximum output current of 50 mA. The maximum value of the voltage spike was 129 mV. Additionally, the recovery time of the LDO was 0.2 µs. [ABSTRACT FROM AUTHOR]

Artificially induced polyploidization is one of the most effective techniques for improving the biological properties and creating new cultivars of fruit trees. Up to now, systematic research on the autotetraploid of sour jujube (Ziziphus acidojujuba Cheng et Liu) has not been reported. 'Zhuguang' is the first released autotetraploid sour jujube induced with colchicine. The objective of this study was to compare the differences in the morphological, cytological characteristics, and fruit quality between diploid and autotetraploid. Compared with the original diploid, 'Zhuguang' showed dwarf phenotypes and decreased tree vigor. The sizes of the flowers, pollen, stomata, and leaves of 'Zhuguang' were larger. Perceptible darker green leaves were observed in 'Zhuguang' trees owing to increased chlorophyll contents, which led to higher photosynthesis efficiency and bigger fruit. The pollen activities and the contents of ascorbic acid, titratable acid, and soluble sugar in the autotetraploid were lower than those in diploids. However, the cyclic adenosine monophosphate content in autotetraploid fruit was significantly higher. The sugar/acid ratio of autotetraploid fruit was higher than that of diploid fruit, which made the autotetraploid fruit taste different and better. The results indicated that the autotetraploid we generated in sour jujube could greatly meet the goals of our multi-objective optimized breeding strategies for improving sour jujube, which includes tree dwarfing, increased photosynthesis efficiency, and better nutrient values and flavors as well as more bioactive compounds. Needless to say, the autotetraploid can also serve as material for generating valuable triploids or other types of polyploids and are also instrumental in studying the evolution of both sour jujube and Chinese jujube (Ziziphus jujuba Mill.). [ABSTRACT FROM AUTHOR]

This paper presents a novel double node upset (DNU) self-recoverable and single event transient (SET) pulse filterable latch design in 28 nm CMOS technology. The loop structure formed by C-elements (CEs) ensures that the latch can self-recover from the DNUs. A Schmitt trigger at the output can filter out transient pulses from anywhere in the circuit. A clock-controlled inverter channel that connects the input to the output reduces the transmission latency. The simulation results show that the proposed design is completely immune to DNUs, and the delay power area product (DPAP) is reduced by more than 50% compared with the previous design. [ABSTRACT FROM AUTHOR]

Conventional switch-mode LED drivers have problems such as poor performance in harmonic distortion, flickering, power factor correction, stresses on the switches, high switching losses, large size, and high cost. To resolve these problems, we propose a long-life LED driver with the ability of power factor correction. The proposed system is based on the integration of a half-bridge LLC resonant converter and two boundary-conducted boost converters. Both boost converters share a common inductor designed in such a way that both boost converters work in boundary conduction mode to attain the natural power factor correction. Half-bridge LLC resonant converter has soft switching characteristics, which assure the zero-voltage switching (ZVS) of primary-side switches and zero-current switching (ZCS) of diodes on the secondary side. This significantly reduces switching losses and improves the overall efficiency of the system. Voltage divider capacitors are used on the input side, which minimizes the bus voltages. The proposed system has two identical secondary windings with a coupled inductor to eliminate the mismatch between them, which powers two independent LED strings. The simulation of a 100-watt 240 V AC converter yields the approximate sinusoidal shape of the input current. It shows that the switches on the primary side are operated in ZVS and the diodes in ZCS. At 240-volt AC input, the efficiency is 87.4%, the total harmonics distortion (THD) is 10.98%, and the power factor (PF) is 0.98. [ABSTRACT FROM AUTHOR]

Background: The molecular mechanisms associated with thoracic aortic dissection (TAD) remain poorly understood. A comprehensive high-throughput sequencing-based analysis of the circRNA–miRNA–mRNA competitive endogenous RNA (ceRNA) regulatory network in TAD has not been conducted. The purpose of this study is to identify and verify the key ceRNA networks which may have crucial biological functions in the pathogenesis of TAD. Methods: Gene expression profiles of the GSE97745, GSE98770, and GSE52093 datasets were acquired from the Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs) were identified using the GEO2R tools. Protein–protein interaction (PPI) networks of the hub genes were constructed using STRING; the hub genes and modules were identified by MCODE and CytoHubba plugins of the Cytoscape. We analyzed the hub genes using Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis. The functions of these hub genes were assessed using Cytoscape software. Our data—along with data from GSE97745, GSE98770, and GSE52093—were used to verify the findings. Results: Upon combined biological prediction, a total of 11 ce-circRNAs, 11 ce-miRNAs, and 26 ce-mRNAs were screened to construct a circRNA–miRNA–mRNA ceRNA network. PPI network and module analysis identified four hub nodes, including IGF1R, JAK2, CSF1, and GAB1. Genes associated with the Ras and PI3K-Akt signaling pathways were clustered in the four hub node modules in TAD. The node degrees were most significant for IGF1R, which were also the most significant in the two modules (up module and hub module). IGF1R was selected as a key gene, and the hsa_circ_0007386/miR-1271–5P/IGF1R/AKT regulatory axis was established. The relative expression levels of the regulatory axis members were confirmed by RT-PCR in 12 samples, including TAD tissues and normal tissues. Downregulation of IGF1R expression in smooth muscle cells (SMCs) was found to induce apoptosis by regulating the AKT levels. In addition, IGF1R showed high diagnostic efficacy in both AD tissue and blood samples. Conclusions: The hsa_circ_0007386/miR-1271-5P/IGF1R/AKT axis may aggravate the progression of TAD by inducing VSMCs apoptosis. CeRNA networks could provide new insights into the underlying molecular mechanisms of TAD. In addition, IGF1R showed high diagnostic efficacy in both tissue and plasma samples in TAD, which can be considered as a diagnostic marker for TAD. [ABSTRACT FROM AUTHOR]

Attackers can exploit compromised hosts to launch attacks over the Internet. This protects an intruder, placing them behind a long connection chain consisting of multiple compromised hosts. Such attacks are called stepping-stone intrusions. Many algorithms have been proposed to detect stepping-stone intrusions, but most detection algorithms are weak in resisting intruders' session manipulation, such as chaff-perturbation. This paper proposes a novel detection algorithm: Packet Cross-Matching and RTT-based two-dimensional random walk. Theoretical proof shows network traffic cross matching can be effective in resisting attackers' chaff attack. Our experimental results over the AWS cloud show that the proposed algorithm can resist attackers' chaff attacks up to a chaff rate of 100%. [ABSTRACT FROM AUTHOR]

There is a large amount of drilling core data in the Mackay River oil sands block in Canada, and the accurate identification of facies from the cores is important and necessary for the understanding of the subsurface reservoir. The traditional recognition method of facies from cores is by human work and is very time consuming. Furthermore, the results are different according to different geologists because of the subjective judgment criterion. An efficient and objective method is important to solve the above problem. In this paper, the deep learning image-recognition algorithm is used to automatically and intelligently recognize the facies type from the core image. Through a series of high-reliability preprocessing operations, such as cropping, segmentation, rotation transformation, and noise removal of the original core image, that have been manually identified, the key feature information in the images is extracted based on the ResNet50 convolutional neural network. On the dataset of about 200 core images from 13 facies, an intelligent identification system of facies from core images is constructed, which realizes automatic facies identification from core images. Comparing this method with traditional convolutional neural networks and support vector machines (SVM), the results show that the recognition accuracy of this model is as high as 91.12%, which is higher than the other two models. It is also shown that for a relatively special dataset, such as core images, it is necessary to rely on their global features in order to classify them, and, with a large similarity between some of the categories, it is extremely difficult to classify them. The selection of a suitable neural network model can have a great impact on the accuracy of recognition results. Then, the recognized facies are input as hard data to construct the three-dimensional facies model, which reveals the complex heterogeneity and distribution of the subsurface reservoir for further exploration and development. [ABSTRACT FROM AUTHOR]

Alien and rare plants tend to adapt to contrasting biotic and abiotic conditions. However, adaptability assessments of alien and rare plants using biological and habitat characteristics in stressful and disturbed environments are limited. We collected and demonstrated the biological and habitat characteristics and assessed the adaptive capacity of alien and rare plants in China using the analytic hierarchy process. Biological characteristics, such as dispersal strategy, sexual and asexual reproduction modes, life form, and habitat characteristics (e.g., habitat type and distribution spatial extent), are important indicators of the adaptability of alien and rare plants to stressful and disturbed environments. Alien plants have a higher adaptive capacity to disturbed environments than rare plants, while rare plants have a higher adaptive capacity to stressful environments than alien plants. Stressful and disturbed environments constrain the adaptive capacity of alien and rare plants, respectively. However, the constraint on alien plants from stressful environments is weaker than that on rare plants from disturbed environments. Understanding the adaptive capacity of alien and rare plants will help researchers and policymakers develop strategies for preventing the invasion of alien plants as well as protecting rare and endangered plants. [ABSTRACT FROM AUTHOR]

In this paper, a novel super-junction trench silicon-on-insulator laterally-diffused metal-oxide-semiconductor (SJT SOI LDMOS) power device with additional hole leakage paths to improve single-event burnout (SEB) performance under high liner energy transfer (LET) is proposed for the first time. The electrical characteristics and SEB performance of the proposed SJT SOI LDMOS are both enhanced effectively. The replacement of a lightly doped N drift region with a heavily doped P pillar and N pillar considerably improves the tradeoff between breakdown voltage (BVDS) and specific on-resistance (Ron,sp). Compared with the conventional trench SOI LDMOS (CT SOI LDMOS), the static figures of merit (FOM, BVDS2/Ron,sp) of the SJT SOI LDMOS increases by 239%. The SEB performance of the SJT SOI LDMOS is significantly improved as the holes induced by the heavy ion can be quickly absorbed to the trench source metal through the heavily doped P+ region and P buried region rather than the base resistor of the parasitic bipolar junction transistor (BJT). The SEB threshold voltage (VSEB) of the CT SOI LDMOS is 58 V (39% of the BVDS) and that of the SJT SOI LDMOS is up to 173 V (87% of the BVDS) at high LET of 1 pC/μm. [ABSTRACT FROM AUTHOR]

Since modern times, the increase in shipborne equipment has brought tremendous pressure to the energy supply system. Establishing an accurate and reliable energy consumption model that reflects the dynamic characteristics of the system will provide an essential theoretical reference for energy efficiency optimization. This paper proposes a modeling method that considers both the dynamic characteristics and energy consumption characteristics of the system, based on the power bond-graph theory. Firstly, the transmission principle and energy transfer process of hydraulic and electric helicopter traction devices are analyzed. Then, the energy consumption is analyzed, and the state equation and energy equation of the system are established. Finally, the simulation tests are carried out. The results show that the proposed dynamic modeling method is reasonable and effective and can well reflect the dynamic characteristics and energy consumption characteristics of the system. [ABSTRACT FROM AUTHOR]

Numerous radiation-hardened-by-design (RHBD) flip-flops have been developed to increase the dependability of digital chips for space applications over the past two decades. In this paper, the radiation immunity and performance of seven well-known RHBD flip-flops are discussed. A novel cross-connected dual modular redundant true single-phase clock (TSPC) D flip-flop (CCDM-TSPC) is proposed. The presented CCDM-TSPC replaces the typical master-slave D flip-flop (MS-DFF) with the fundamental TSPC structure to shorten the circuit's propagation time. All sensitive points in the circuit are radiation-hardened by using means of cross-connection. The simulation results of the SPECTRE tool show that CCDM-TSPC is completely immune to single-event upsets (SEUs). CCDM-TSPC reduces the C-Q delay by 75% and the layout area by 85% compared with the traditional triple modular redundancy D flip-flop (TMR-DFF). [ABSTRACT FROM AUTHOR]

Current aerodynamic parameter identification methods take the consistency between the response of the motion model reconstructed with the identified aerodynamic parameters and flight data as an optimization index. Since there is only one index constraint in aerodynamic parameter optimization, and more than ten aerodynamic parameters to be identified simultaneously have different sensitivity to the optimization index, the accuracy of identification results of parameters with low sensitivity is poor, especially for those with small absolute value. To solve these problems, a new idea, having aerodynamic parameters solved by balance equations and identified in stages, is proposed. Based on the motion characteristics of different lateral-directional maneuvers, the scheme of combined maneuvers is designed, and the step-by-step identification procedure is established. An estimation method of angular acceleration with angular velocity equivalent model is proposed to solve the problem that angular acceleration cannot be measured directly. A lateral-directional aerodynamic parameter identification method using segmented adaptation of flight data and identification models is established based on the identifiability of flight data. The lateral-directional aerodynamic parameter identification results of a large civil aircraft show the identification results can be obtained with higher accuracy by adopting the proposed identification method and the flight test scheme. [ABSTRACT FROM AUTHOR]

The timely delivery of status information collected from sensors is critical in many real-time applications, e.g., monitoring and control. In this paper, we consider a scenario where a wireless sensor sends updates to the destination over an erasure channel with the supply of harvested energy and reliable backup energy. We adopt the metric age of information (AoI) to measure the timeliness of the received updates at the destination. We aim to find the optimal information updating policy that minimizes the time-average weighted sum of the AoI and the reliable backup energy cost. First, when all the environmental statistics are assumed to be known, the optimal information updating policy exists and is proved to have a threshold structure. Based on this special structure, an algorithm for efficiently computing the optimal policy is proposed. Then, for the unknown environment, a learning-based algorithm is employed to find a near-optimal policy. The simulation results verify the correctness of the theoretical derivation and the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

For deep-buried thick top-coal roadways under high stress, there exists great difficulty in controlling the stability of the surrounding rock as well as in the necessity for low driving speeds. Taking the return air roadway 20201 (RAR 20201) of the Dahaize Coal Mine as the background, this paper presents a typical engineering case of a deep-buried thick top-coal roadway in a western mine. Through methods such as in situ investigation, theoretical analysis, numerical simulation and engineering practice, we studied the deformation and failure mechanisms of the surrounding rock in a deep-buried high-stress thick top-coal roadway, and revealed the driving speed effect. Results show that compared with shallow buried roadways, the deep-buried thick-roof coal roadway suffers a greater range of damage and failure. The roof damage is so deep that it exceeds the action range of bolts, resulting in the stress transferring to both sides, which affects the stability of the roadway surroundings. The curve of unloading disturbance stress produced by roadway head-on driving is in accordance with the "power exponential" composite function; that is, the faster the driving speed, the less unloading disturbance intensity that is exerted on the roof strata. This paper puts forward targeted cooperative control countermeasures of efficient driving and support in a deep-buried thick top-coal roadway. On one hand, the support efficiency of a single bolt is improved so as to reduce the overall support density; on the other hand, under low support density, the driving-supporting circulation efficiency is also accelerated so as to weaken the unloading disturbance and improve roadway formation speed. Engineering practice shows great control effect of the roadway surrounding rock, and the roadway formation speed is also greatly improved. This research can provide reference for efficient driving and support design in similar deep-buried thick top-coal roadways. [ABSTRACT FROM AUTHOR]

The Yellow River Basin of Inner Mongolia has significant ecological advantages, and it is critical to research the landscape pattern of its watershed wetland ecosystem and the changes in its service value in order to protect the environment and develop the region in a high-quality manner. In this paper, we use the landscape index method, the equivalent factor method, and a field survey to investigate changes in wetland landscape patterns and the dynamics of wetland ecosystem service values in the Yellow River Basin of Inner Mongolia from 1990 to 2020, and then examine the impact of landscape pattern evolution on wetland ecosystem service values in the region. The study's findings indicate that rivers, lakes, and herbaceous marshes are the most common types of wetland landscapes in Inner Mongolia's Yellow River Basin. The landscape types in the research area are diverse, and landscape fragmentation is increasing. In the Yellow River Basin of Inner Mongolia, the overall value of wetland ecosystem benefits is negatively connected with Patch Density and the Shannon Diversity Index, and positively correlated with the Contagion Index. [ABSTRACT FROM AUTHOR]

Coal is an important resource for China and even for the whole world. With the improvement of mechanization, automation and intelligence of coal mining equipment in China, there has been an imbalance between the speed of mining and of excavating. Adopting efficient cutting paths is beneficial to improving roadway excavation efficiency and alleviating the imbalance between mining and excavation. In this paper, taking the 12307 belt roadway of Wangjialing Coal Mine as the research background, the geomechanical parameters and distribution characteristics of the surrounding rock were observed and studied, and the test results of in-situ stress, surrounding rock structure and surrounding rock strength were obtained. Based on the test results, a numerical model was established, and the stress and displacement distribution law of the surrounding rock of the roadway under different cutting paths were analyzed, and two optimal cutting paths were proposed based on the actual situation, and industrial tests were carried out. The test results show that using the "snake" cutting path from bottom to top, the roadway section forming effect is good, and a single cycle excavation takes 34 min, which verified the effectiveness of the cutting path design. On the basis of specific engineering geological conditions, excavation equipment and technology, combined with experimental testing, numerical simulation and other methods, the roadway excavation cutting path can be optimized, and the research results can provide a reference for the design of cutting paths for coal mine excavation roadways with the same geological conditions. [ABSTRACT FROM AUTHOR]