bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of thermochemical non-equilibrium effects on non-uniform entrance scramjet nozzle
Authors: Wang Jinping , Zhuo Changfei , Ren Xiaobin
Published: May 2024

The high Mach number scramjet nozzle flow has prominent non-uniform characteristics and high-temperature non-equilibrium effects. Thus, the thermochemical non-equilibrium gas model was developed for simulating flows in the non-uniform and uniform entrance of a Mach 10 hydrocarbon fuel scramjet nozzle. The results show that the non-uniform entrance has a higher non-uniform degree in the flow-field compared to the uniform entrance. Additionally, the expansion degree inside the nozzle is greater and the thermal non-equilibrium effects downstream of the nozzle exit are stronger. The non-uniform entrance condition has a more intense chemical reaction near the nozzle exit but has less impact on the flow parameters. For the nozzle performance, under the influence of the non-uniform entrance, the greater gas expansion degree inside the nozzle results in a lower pressure acting on the upper wall, and then the nozzle thrust decreases by 1.68%. Hence, the structural design and performance optimization of the high Mach number scramjet nozzle must consider entrance non-uniform characteristics and thermochemical non-equilibrium effects.
Aero-acoustics study of coupled cavities in close proximity along a rectangular flow duct at low Mach number
Authors: Tang Y J , Gan L , Liang C , Gao J L , Zhang S Z
Published: May 2024

In present study, a series of flow induced noise experiments were investigated by a coupled cavity with low Mach number flow. A new signal processing method was derived to analyze the turbulence sound field and its propagation inside the coupled cavity region. In order to investigate the sound field in the presence of flow throughout the coupled cavity regions, a transfer function technique for transducer signals was developed. Experimental result and analysis show that the significant sound attenuation effect is caused by the pressure fluctuation that gives rise to canceling waves along the main duct section. In the presence of the acoustic excitation and the duct flow, the Rossiter type of feedback is the dominant mechanism responsible for the sound amplification effect. This type of feedback mechanism also results in relatively tonal sound generations at various frequencies within the working bandwidth of the coupled cavities.
A hybrid dynamics modeling method for micro-turbine engine thrust vectoring
Authors: Chao Zhang , Aobo Shi , Guangqi Cheng , Jian Sun
Published: May 2024

Thrust vector control technology is widely used in modern advanced aircrafts, space shuttles and unmanned aerial vehicles, etc. An accurate thrust vector mathematical model is of great significance to enhance the thrust vector control effect. In this paper, the P200 micro-turbine engine with an axisymmetric thrust vector nozzle placed at the rear is taken as an example, A hybrid thrust vectoring dynamics modeling method consisting of engine speed model, engine thrust model, actuator dynamics model, airflow angle model and thrust loss coefficients is proposed. The engine speed model is of Linear Parameter Varying (LPV) model with each segment is characterized by a First Oder Plus Dead Time (FOPDT) model. The engine thrust model is characterized as a cubic polynomial function of engine speed. The actuator’s dynamic model is a FOPDT model. The nozzle airflow deflection angle is proportional to the airflow deflection angle. the thrust loss coefficient is approximated by a cosine relationship with the airflow deflection angle. The experimental results show that the established model can well characterize the dynamics of the thrust vector system.
CF-LSTM-based post-maneuver position prediction for GEO spacecraft
Authors: Long X , Yang L P , Huang H , Hu J X , Qiao C Y
Published: May 2024

Prediction of the position of Geosynchronous (GEO) spacecraft after a maneuver is crucial for space domain awareness (SDA), as it can enhance the flexibility of the space surveillance network (SSN). The longitude is a unique parameter that can be freely assigned to GEO spacecraft. In this paper, we propose a prediction model for the longitude of a GEO spacecraft based on Causal Feature Long Short-Term Memory networks (CF-LSTM). Initially, we analyze the historical data of GEO spacecraft in a time-series geographic position and identify the causal parameters of longitude using the Gaussian perturbation equation. Subsequently, we present the CF-LSTM to predict the longitude. Our experimental analysis shows that the proposed method reduces the mean absolute error (MAE) and mean square error (MSE) by 60.92% and 18.75%, respectively, compared to conventional LSTM.
Physical and mechanical impact of Y2O3 on (Cu-7Ag) electrical contact alloy
Authors: Raheem Maryam , Al-Ethari Haydar , Abbas Sundus
Published: May 2024

In this study, (Cu-7Ag) alloy was synthesized through powder metallurgy rout and explored the effect of adding yttrium oxide (Y2O3) with three different volume fractions 2, 4, and 6 vol.%. The effects were recorded on the electrical conductivity, the hardness, and the wear rate of the prepared samples. The base samples were sintered at 850 °C for 4 hours, while the composite samples were sintered with two holding times: at 550 °C for 2 hours and at 850°C for 4 hours. All of the sintered samples were homogenized at 777 °C for an hour followed by aging at 400 °C for 8 hours. The base alloy (Cu-7Ag alloy) showed higher conductivity but poor hardness and poor wear resistance. Best balance between the improvement of mechanical properties and suitable electrical conductivity had been obtained with Cu-7Ag+4vol.% Y2O3 composite sample.
Integrated design optimization of ducted lift fan for lift enhancement and noise reduction based on nested NFFD control body
Authors: Zhang Linxuan , Sun Jian , Cai Xiaofei , Zhang Chao , Ding Yuheng
Published: May 2024

In order to enhance the aerodynamic performance and reduce the aerodynamic noise of the coaxial dual-rotor ducted fan, this paper proposes a stepwise optimization strategy based on nested NFFD (Nurbs-Based Free-Form Deformations) control body parameterization. This strategy takes into account the optimization of aerodynamic performance, which involves significant deformations, and noise reduction, which requires fine deformations. By doing so, it effectively addresses the issue of drastically increased computational complexity and time consumption associated with conventional multi-objective optimization methods. By designing the aerodynamic shape of the blades, along with aerodynamic performance parameter calculation and aerodynamic noise calculation modules, it is possible to achieve lift enhancement and noise reduction for the ducted fan. The numerical simulation results demonstrate that the flow field over the optimized blade surface is improved significantly. The lift has increased from 3.45N to 3.54N, resulting in a 2.6% enhancement. Additionally, the noise level has decreased from 72.33dB to 69.52dB, achieving a noise reduction of 2.81dB.
Design of dynamic test specimens and fixtures for large structural components of civil aircraft
Authors: Lyu Yuanzhou , Li Ruowei
Published: May 2024

In the course of designing and certifying civil aircraft, a significant number of dynamic tests are necessary. If the test specimen is too large in volume or weight, it will place higher demands on the loading capacity of the test equipment. The main focus in the design process of dynamic test specimens is to ensure consistency in the dynamic characteristics compared to the original structure, specifically with regard to natural frequency and mode shapes. Factors such as stiffness, damping, and boundary conditions are taken into consideration. In order to facilitate test implementation and reduce manufacturing costs, a combined approach involving finite element analysis and experimental verification is employed to provide guidance for the design of dynamic test specimens and fixtures for civil aircraft.
Developing and correction methods for a one-dimensional axial flow compressor model
Authors: Deng Haomin , Zhou Wenxiang , Cong Jingmei , Zhang Chenyang , Wu Jichang , Huang Jinquan
Published: May 2024

This paper establishes a one-dimensional model of an axial flow compressor using the Average Mid-Diameter Method and employs polynomials to adjust the off-design stagger angle and off-design loss models. Furthermore, a model stepwise correction strategy based on the Particle Swarm Optimization (PSO) algorithm is proposed. The accuracy of the corrected one-dimensional axial flow compressor model was verified and integrated into the overall engine model for validation. Simulation results indicate that the maximum error in calculating the characteristics of the established one-dimensional axial flow compressor model does not exceed 6%, and the maximum error in simulating the overall engine model remains below 4%. These findings validate the effectiveness of modeling and correction methods for a one-dimensional axial flow compressor model targeting aero-engine component-level model.
Application of CNN-IndRNN model combined with residual structure in aircraft engine EGT prediction
Authors: Xiao Dasheng , Xiao Hong
Published: May 2024

The convolutional neural network (CNN), independently recurrent neural network (IndRNN), and residual structure are used to establish a deep learning model for predicting the exhaust gas temperature (EGT) of aircraft engines. Compared to traditional RNN, the IndRNN has an independent recurrent weight matrix in each unit unfolded in the time dimension, which can more efficiently capture spatiotemporal information. Meanwhile, CNN can capture salient features from the multi-feature and multi-time-step data of the original input. Subsequently, the salient features extracted are combined with the initial input using the residual structure before being fed into the IndRNN module. A case study is conducted on the flight data of two civil aircraft engines to verify the effectiveness of IndRNN compared to traditional RNN. The proposed CNN-IndRNN model can accurately predict the EGT of aircraft engines, with a mean absolute relative error below 1.0%.
Experimental and numerical study of a fluidic oscillator frequency domain characteristics
Authors: Wu Xiyun , Li Kuo , Cao Dalu , Pi Kaiwen
Published: May 2024

Fluidic oscillators are fluid devices that provide steady flow at the inlet while generating unsteady flow at the outlet. This paper aims to investigate the frequency domain characteristics of internal pressure fluctuations in a specific type of fluidic oscillator to gain a deeper understanding of its dynamic behavior. The following conclusions were drawn: (1) Within a certain range, as the inlet-to-outlet pressure ratio increases, the oscillation frequency of the fluidic oscillator continuously rises, and the oscillation amplitude strengthens. (2) As the jet nozzle velocity increases within a certain range, the jet oscillation frequency exhibits a linear upward trend. These research findings provide essential academic and engineering guidance for designing and applying fluidic oscillators, assisting engineers in better understanding and controlling the device’s performance to meet the requirements of various application domains.
Real-time improvement method of turbo-shaft engine component-level model based on dimensional reduction of residual iterative equation
Authors: Li Guochang , Zhou Wenxiang , Huang Xinsheng , Peng Wenhui , Shan Xiaoming
Published: May 2024

This paper explores a method to improve the real-time computation performance of turbo-shaft engine component-level model by reducing the dimensionality of residual equations set. For turbo-shaft engine, nozzle typically operates in a subcritical working state, assuming that the gas total temperature and pressure parameters of power turbine inlet are the same, and by assuming the gas flow balance between gas generator outlet and nozzle inlet, the iterative solution of the pressure drop of nozzle can be obtained. Then the pressure ratio of power turbine is naturally obtained, thereby achieving the objective of dimensionality reduction of the residual equations set. The component-level model’s steady-state and transient performance were simulated on a desktop computer with a clock frequency of 2.6 GHz. Simulation results show that, with a 2% margin of error, the steady state computation time for the component-level model was reduced by 54.8%, while the transient performance computation time was reduced by 18.6%. This represents a noticeable improvement in real-time performance. Simulation results on the P2020 embedded processor platform with an 800MHz clock frequency indicate a 22.3% reduction in single-step maximum transient performance computation time of the reduced dimensional model, compared to the original model. This demonstrates the effectiveness of dimensionality reduction of the residual equations set in enhancing the model real-time computation performance.
Simulation study on the breakup process of kerosene Gel Jet in transverse airflow
Authors: Zhou Ziqi , Wang Dong , Wang Yong , Xia Zhenjuan
Published: May 2024

The gel propellant not only inherits the characteristics of liquid propellants, such as high specific impulse, multiple ignition capabilities, and adjustable thrust, but also offers an advantage type of solid propellants, including reduced risk of leakage, long-term storage feasibility, and ease of maintenance. In this study, numerical simulations were conducted to investigate the atomization and mixing process of kerosene gel jets in high-speed crossflows. The study reveals that the jet breakup process primarily involves two forms of breakup: columnar breakup dominated by Rayleigh Taylor’s unstable wave and surface breakup dominated by Kelvin Helmholtz’s unstable wave. These two forms coexist, complement each other, and interact with each other. The numerical simulation of the kerosene gel breakup process provides favorable support for studying its combustion characteristics in the rotating detonation engine.
Simulated annealing-particle swarm optimization initial orbit determination method for too-short-arcs
Authors: Li Xinyang , Xie Chunlei , Zhang Qi , Xu Wuxin , Chen Zhihong
Published: May 2024

The initial orbit determination (IOD) of a non-cooperative satellite through space-based optical angle-only measurement data is a fundamental task. However, due to the lack of relative distance information of the targets, traditional methods have problems with poor accuracy and robustness in orbit determination results. The application of particle swarm optimization algorithm for IOD under optical too-short-arcs (TSA) measurement data has achieved good results. However, there is still a problem of convergence to local extremum. This article proposes a simulated annealing-particle swarm optimization (SA-PSO) hierarchical algorithm, which combines the efficient searchability of particle swarm optimization with the fine searchability of simulated annealing algorithm to achieve robust and precise optimization of non-cooperative targets orbit elements. The experimental results show the SA-PSO algorithm significantly improves the accuracy of orbit elements prediction compared to the particle swarm optimization algorithm and proves its effectiveness.
Obstacle avoidance motion planning for space redundant manipulator based on improved RRT algorithm
Authors: Ye Bin , Liu Chuankai , Han Fang , Hu Xiaodong , Chen Li
Published: May 2024

In addressing the challenge of obstacle-avoidance motion planning for space redundant manipulators operating in environments with obstacles, an improved method based on a rapidly exploring random tree (RRT) algorithm is proposed. The method first adopts a target probabilistic sampling strategy to enhance the target orientation. Secondly, an artificial potential field is constructed to steer the growth of the node tree in joint space. Subsequently, a collision detection model between the manipulator and obstacles is established based on the bounding capsule and bounding sphere in Cartesian space. Finally, the paths are pruned and smoothed with a cubic Bezier curve. The simulation results validate the method’s capacity to effectively plan a collision-free path for the space redundant manipulator and the joint motion trajectory is smooth.
Research on force-controlled polishing system for robotic arm based on compliance control
Authors: Xiao Jianming , Zhou Xinrui
Published: May 2024

This thesis enhances robotic arm control in intricate polishing environments by using impedance control for consistent force regulation between the arm and workpiece. An adaptive impedance control algorithm accommodates contact force variations, boosting system robustness. The PSO-BP variable impedance controller integrates particle swarm optimization and BP neural network for real-time optimization, overcoming limitations of fixed-parameter impedance control on surfaces with curvature changes. Experimental results show a significant reduction in polishing force fluctuations and improved force tracking. These findings support efficient robotic arm utilization in polishing tasks.
Research on longitudinal control technology in the transition section of tilt-rotor aircraft based on linear active disturbance rejection control
Authors: Xu Shaofeng , Chang Shaoping , Shi Pengfei , Wang Lin
Published: May 2024

To solve the problem of strong coupling and control redundancy in the transition section of the tilt-rotor, this paper presents a longitudinal control method based on linear active disturbance rejection control (LADRC), verified by simulation. Firstly, the nonlinear dynamics model of tilt-rotor aircraft based on the mechanism method is established, and the model’s accuracy is verified by comparing the trim result with the generic tilt-rotor aircraft simulation (GTRS) model verified by flight test in XV-15. Then, the control and redundant rudder surface assignment strategies for tilt-rotor aircraft are proposed. Then, the vertical and vertical control law of tilt-rotor aircraft is designed, the linear expansion state observer (LESO) model is analyzed and derived, and the linear active disturbance rejection controller suitable for attitude loop control of tilt-rotor is designed. The altitude and velocity loops are controlled. Finally, the proposed linear active disturbance rejection control (LADRC) controller is verified by simulation, and the whole process of tilting transition is simulated. The results show that the proposed control strategy and the controller designed in this paper have strong anti-disturbance ability, fast response speed, and high control precision and can be used in the transition section of tilt-rotor aircraft. The vertical direction shall be well controlled.
The research focuses on the interception guidance method during the boost phase
Authors: Xu Zhang , Peng Zeng , Xu Li , Heng Xue Jian , Rui Liu
Published: May 2024

To effectively intercept enemy ballistic missiles during the boost phase, the interceptor must possess high velocity and acceleration capabilities, necessitating a guidance mechanism capable of maneuvering precisely with the target. This paper analyzes the characteristics of booster phase interceptor missiles based on relevant research and establishes a trajectory simulation model. Considering the required guidance performance throughout the missile’s flight process, we design guidance laws for the initial, mid-course, and final stages to conduct trajectory simulations. The results demonstrate that the guidance law proposed in this paper outperforms the conventional guidance mechanism regarding miss distance, ballistic angle, and required overload. Moreover, it satisfies the interception accuracy requirements during the boost phase interception.
A forward design approach for fault thresholds in redundant flight control systems
Authors: Gao Xin , Zhang Junhong , Gong Lei
Published: May 2024

Modern fly-by-wire flight control systems use redundancy configurations to meet high safety requirements. The fault threshold value of the redundancy monitoring and voting algorithm affects the false alarm rate and missing alarm rate of the flight control system and the excessive false alarm rate and missing alarm rate reduce the reliability of the flight control system. Traditionally, the design of fault threshold is based on the empirical trial-and-error method, which suffers from the problem of unclear optimization direction. Forward design is needed to improve design efficiency and quality. In this paper, a forward design method for fault detection threshold is proposed to determine the upper limit value of the fault threshold by analyzing the effect of the voting signal change on the transient response of the aircraft when a channel fault occurs. The lower limit value of the fault threshold is determined by analyzing the channel history data. The effectiveness of the design method is demonstrated by digital simulation.
Trajectory tracking control of four-rotor UAV based on nonlinear extended state observer and model predictive control in wind disturbance environment
Authors: Chen Cen , Zhang Xiaoli , Peng Xiafu
Published: May 2024

In this paper, a novel hybrid controller utilizing a nonlinear extended state observer (NLESO) is introduced. According to the Newton-Euler equation, the four-rotor UAV is modeled and divided into the position subsystem and attitude subsystem. The position subsystem is controlled using the Model Predictive Control (MPC) algorithm. At the same time, the attitude controller utilizes the Sliding Mode Control (SMC) algorithm, which provides an enhanced level of responsiveness, resulting in reduced response times. The Nonlinear Extended State Observer (NLESO) is used in each controller in order to counteract the effects of disturbances. The findings obtained from the simulation experiments demonstrate that the controller design exhibits favorable tracking performance and robust resistance against external disturbances.
Modal frequency identification using the predictor subspace approach for a space solar power station
Authors: Ni Zhiyu , Wu Rui , Wu Chenchen
Published: May 2024

The system’s modal frequency parameters are determined by using a technique known as predictor-based subspace identification (PBSID), which is based on the dynamic properties of space solar power stations’ huge size and low frequency. First, the dynamic equation for the space solar power station with an Abacus configuration’s attitude-vibration coupling is developed. Additionally, the PBSID approach is used to build the relevant parameter matrix, and singular value decomposition (SVD) is chosen to evaluate the system’s structural frequency parameters. The right input signals are created via numerical simulation, and the best sensor placement technique yields the associated vibration response signals. The computing results then demonstrate that the modal frequency characteristics of the space solar power station may be successfully identified by the PBSID method, which is based on SVD. Additionally, the findings demonstrate the superior noise immunity capabilities of the PBSID algorithm when compared to the standard modal parameter identification approaches.
Low-thrust trajectory optimization of deep space exploration based on discrete pulse method
Authors: Qin Lin , Shang Haibin , Dong Yue , Zhao Zichen
Published: May 2024

Deep space exploration is gradually becoming the hot mission of human space activities, and this kind of mission has the characteristics of a long mission cycle, complex space environment, high fuel demand, and difficult telemetry track and command, etc. It is the future trend to carry out deep space exploration activities using low-thrust propulsion systems, and the trajectory optimization of interplanetary missions is one of the significant difficulties. Considering the characteristics and difficulties of interplanetary missions, a method of transfer orbit preliminary design in the multi-body system is proposed in this paper. The simulation results illustrate that the transfer orbit obtained by the method in this paper can provide a reliable initial guess for the optimization of high-precision orbit and decrease convergence sensitivity. The research results can provide a significant reference for the implementation of deep space exploration missions in China in the future.
Moderate Indian Ocean Dipole dominates spring fire weather conditions in southern Australia
Authors: Ren Xuya , Zhang Li , Cai Wenju , Wu Lixin
Published: May 2024

Patterns of the Indian Ocean Dipole (IOD) exhibit strong diversity, ranging from being dominated by the western tropical Indian ocean (WTIO) to by the eastern tropical Indian ocean. How the different types of the IOD variability patterns affect Australian fires differently is unknown, nor is it certain how the impacts may change under greenhouse warming. Here, we find that the moderate IOD, dominated by WTIO sea surface temperature (SST) variability, plays a primary role in affecting southern Australian fire weather conditions during austral spring. During a positive moderate IOD, broad-scaled warm SST anomalies in WTIO force an atmospheric stationary Rossby wave with a high-pressure anomaly over southern Australia. This elevated pressure and associated anomalous atmospheric conditions provide suitable fire weather with hot, dry, and windy conditions, raising fire risks in southern Australia. Such impact is distinctively different from that strong IOD-induced. As predicted by climate models, decreased moderate IOD variability in the future will result in weakened Australian fire weather responses.
Modulation of East Asian atmospheric rivers by the Pacific-Japan teleconnection pattern
Authors: Kwon Yeeun , Park Chanil , Son Seok-Woo , Kim Jinwon
Published: May 2024

Despite growing recognition that atmospheric rivers (ARs) play an important role in summer monsoon rainfall in East Asia, the AR variability related to low-frequency (LF) climate modes remains largely unknown. This study reports the significant control of the Pacific-Japan (PJ) teleconnection pattern on East Asian summer ARs. While Korea and central to eastern Japan experience more frequent, intense, and persistent ARs during the positive PJ, ARs in eastern China become more active during the negative PJ. Such AR activity changes are closely related to the PJ modulation of the western North Pacific subtropical high along which anomalous moisture transport organizes on the LF time scale. This finding suggests that the PJ pattern is an important source of East Asian summer AR variability and needs to be considered in medium-range forecasts of AR-related hydrological extremes.
Synthesis, mechanical and tribological behaviours of boron nitride reinforced AA7075 composites produced by stir casting technique
Authors: Kumar R Ranjith , Ravichandran M , Alagarsamy S V
Published: May 2024

This experimental investigation focused on synthesis of aluminium 7075-boron nitride (BN) composites (AA7075-BN), using stir casting technique. Four various proportions of BN of 0, 4, 8 and 12 wt% were used for the production of the composites. Scanning electron microscopy (SEM) was used to study the microstructure of the prepared composites. Using a pin-on-disc equipment, wear test was performed to analyse the tribological characteristics of the as-casted composites. The wear rate (WR) and the co-efficient of friction (COF) were determined by altering the input parameters, such as reinforcement (R), applied load (L), sliding velocity (V) and sliding distance (D). A grey relational technique (GRT) was applied to determine the appropriate conditions of parameters and showed low WR and COF for the composites. From the experimental results obtained, the least density of the composite was 2.70 g cm−3 for AA 7075–12 wt% BN. The mechanical properties of the composites were significantly improved. The highest tensile strength of 210 MPa was obtained from the same AA 7075–12 wt% BN. There was 26% of improvement in the tensile strength with 4 wt% of BN reinforcement in AA7075 matrix. Finally, the worn surface morphology confirmed plough and furrow formations on the AA 7075–4 wt% BN and AA 7075–8 wt% BN composites, respectively. Therefore, the applications of the various composites depend on their responses to the properties, as studied.
Model to identify comfortable cloth fabric for human body during thermal stress due to physical exercise
Authors: Patidar Neelam , Makrariya Akshara , Rasheed Rassol Hamed , Kumar Singh Nitish , Alsayah Ahmed Mohsin , Alshukri Mohammed J , Rathore Ram Krishna
Published: May 2024

Physical exercise enhances heat generation in human skin and subcutaneous tissues causing thermal stress. This thermal stress causes discomfort in the human body and deteriorates the physical performance of the human subjects. Appropriate choice of cloth for outer covering of human body is necessary to prevent this to provide comfort during the thermal stress. A mathematical model is proposed in this study to analyze the thermal stresses in human skin and subcutaneous tissues covered with various different cloth fabrics. The model considers four compartments namely cloth, epidermis, dermis, subcutaneous tissues. The bioheat equation along with appropriate boundary condition is employed in this model for one dimensional unsteady state case. The numerical simulation is performed using forward and central finite difference formulas. The findings have been utilized to examine how different types of fabric impact thermal stress experienced by the layers of human skin during physical activity. The polyester is found to be superior in comparison to cotton fabric as it shows less thermal stress and thus can be concluded to be more comfortable as a dress material.
Optimizing motor imagery BCI models with hard trials removal and model refinement
Authors: R Vishnupriya , Ramasubba Reddy MachiReddy
Published: May 2024

Deep learning models have demonstrated remarkable performance in the classification of motor imagery BCI systems. However, these models exhibit sensitivity to challenging trials, often called hard trials, leading to performance degradation. In this paper, we address this issue by proposing two novel methods for identifying and mitigating the impact of hard trials on model performance. The first method leverages model prediction scores to discern hard trials. The second approach employs a quantitative explainable artificial intelligence (XAI) approach, enabling a more transparent and interpretable means of hard trial identification. The identified hard trials are removed from the entire motor imagery training and validation dataset, and the deep learning model is further re-trained using the dataset without hard trials. To evaluate the efficacy of these proposed methods, experiments were conducted on the Open BMI dataset. The results for hold-out analysis show that the proposed quantitative XAI- based hard trial removal method has statistically improved the average classification accuracy of the baseline deep CNN model from 63.77% to 68.70%, with p-value =

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for the subject-specific MI classification. Additionally, analyzing the scalp map representing the average relevance scores of correctly classified trials compared to a misclassified trial provides a deeper insight into identifying hard trials. The results indicate that the proposed quantitaive-based XAI approach outperformes the prediction-score-based approach in hard trial identification.
Lung segment anything model (LuSAM): a decoupled prompt-integrated framework for automated lung segmentation on chest x-Ray images
Authors: Iytha Sridhar Rishika , Kamaleswaran Rishikesan
Published: May 2024

Accurate lung segmentation in chest x-ray images plays a pivotal role in early disease detection and clinical decision-making. In this study, we introduce an innovative approach to enhance the precision of lung segmentation using the Segment Anything Model (SAM). Despite its versatility, SAM faces the challenge of prompt decoupling, often resulting in misclassifications, especially with intricate structures like the clavicle. Our research focuses on the integration of spatial attention mechanisms within SAM. This approach enables the model to concentrate specifically on the lung region, fostering adaptability to image variations and reducing the likelihood of false positives. This work has the potential to significantly advance lung segmentation, improving the identification and quantification of lung anomalies across diverse clinical contexts.
Investigation on ultrasound images for detection of fetal congenital heart defects
Authors: S Satish , Rufus N Herald Anantha
Published: May 2024

Congenital heart defects (CHD) are one of the serious problems that arise during pregnancy. Early CHD detection reduces death rates and morbidity but is hampered by the relatively low detection rates (i.e., 60%) of current screening technology. The detection rate could be increased by supplementing ultrasound imaging with fetal ultrasound image evaluation (FUSI) using deep learning techniques. As a result, the non-invasive foetal ultrasound image has clear potential in the diagnosis of CHD and should be considered in addition to foetal echocardiography. This review paper highlights cutting-edge technologies for detecting CHD using ultrasound images, which involve pre-processing, localization, segmentation, and classification. Existing technique of preprocessing includes spatial domain filter, non-linear mean filter, transform domain filter, and denoising methods based on Convolutional Neural Network (CNN); segmentation includes thresholding-based techniques, region growing-based techniques, edge detection techniques, Artificial Neural Network (ANN) based segmentation methods, non-deep learning approaches and deep learning approaches. The paper also suggests future research directions for improving current methodologies.
Research on green development measurement and regional differences in the China's Yellow River Basin based on the ecological function orientation
Authors: Ma Yubin , Dong Mingfang , Yao Shujun , Chen Haotian , Hu Xiaobing , He Liwen , Li Zhengda
Published: May 2024

The ecological protection and high-quality development of the Yellow River Basin have become a national strategy. This study takes 57 cities in the Yellow River Basin as research samples, employs the green total factor productivity (GTFP) to characterizes the level of green development, introduces an improved mixed distance (MEBM) Windows model and an algorithm containing the background differences to measure the level of green development, and further uses the Dagum Gini coefficient to analyze the regional differences. It shows that the level of green development of Yellow River Basin exhibits a downward trend during the study period when the ecological function orientation (EFO) is not considered, however, the downward trend is significantly narrowed when the EFO is considered, and 91.23% of the sample rankings is changed. According to these results, the study samples are divided into three types: the controlled development zones, the moderate development zones, and the transition development zones. The inter-regional differences are the main factors that causes the regional differences in the green development of Yellow River Basin. Based on the results, we propose the relevant policy recommendations that can provide a decision-making basis for promoting the ecological protection and high-quality development in the Yellow River Basin according to the local conditions.
Holistic and localized preparation methods for triboelectric sensors: principles, applications and perspectives
Authors: Gao Zhenqiu , Wu Shaokuan , Wei Yihan , Ibrahim Mervat , Abdelhamid Hani Nasser , Jiang Guyu , Cao Jun , Sun Xuhui , Wen Zhen
Published: May 2024

With the arrival of intelligent terminals, triboelectric nanogenerators, as a new kind of energy converter, are considered one of the most important technologies for the next generation of intelligent electronics. As a self-powered sensor, it can greatly reduce the power consumption of the entire sensing system by transforming external mechanical energy to electricity. However, the fabrication method of triboelectric sensors largely determines their functionality and performance. This review provides an overview of various methods used to fabricate triboelectric sensors, with a focus on the processes of micro-electro-mechanical systems technology, three-dimensional printing, textile methods, template-assisted methods, and material synthesis methods for manufacturing. The working mechanisms and suitable application scenarios of various methods are outlined. Subsequently, the advantages and disadvantages of various methods are summarized, and reference schemes for the subsequent application of these methods are included. Finally, the opportunities and challenges faced by different methods are discussed, as well as their potential for application in various intelligent systems in the Internet of Things.
Techniques of creating in-plane fiber waviness in composites and its mechanical performance – a review
Authors: Muddebihal Aravind , Shivakumar Gouda P S , Uppin Vinayak S
Published: May 2024

In-plane fiber waviness is a common manufacturing flaw in composites, which can be observed during the production of items such as wind turbine blades, industrial components, aircraft structures, and automobile parts, etc. When manufacturing large composite structures, the traditional hand lay-up with fabric is labor-intensive and comes with several other issues, leading to various defects. One major but often overlooked defect is in-plane fiber waviness. The current investigation provides an overview of creating several techniques of in-plane fiber waviness faults in composites. Previously, numerous techniques were reported by researchers, employed to induce in-plane fiber waviness with specific parameters for their investigations. An effort has been made to highlight the various non-destructive techniques used for characterizing in-plane fiber waviness. Additionally, this paper presents a compilation of data on the impact of in-plane fiber waviness on the mechanical performance of composites. The paper concludes by proposing scope for additional research in the area of in-plane fiber waviness. Further, a novel method was proposed for creating in-plane fiber waviness which can reduce the possible fiber rotation using semi-circular wooden bars along with clamping arrangements instead of circular bars in the earlier investigations. Consequently, this could be a significant approach which resembles with realistic in-plane waviness generated while producing fiber reinforced polymer (FRP) composite components.
Densities of neuston often not elevated within plastic hotspots territory inside the North Pacific Garbage Patch
Authors: Egger Matthias , van Vulpen Marjolein , Spanowicz Kiri , Wada Kyle , Pham Yannick , Wolter Helen , Fuhrimann Samuel , Lebreton Laurent
Published: May 2024

The North Pacific Garbage Patch, located in the eastern part of the North Pacific subtropical gyre, contains vast amounts of floating plastic debris. Research over the past decades has mainly focused on assessing the extent of plastic pollution in this oceanic region. However, the North Pacific subtropical gyre is also home to the surface-associated pelagic community known as neuston. To date, the dynamics of this ecosystem and its vulnerability towards environmental pollution and anthropogenic impacts remain poorly understood. While removing plastic debris afloat at sea can reduce negative impacts of plastic pollution on neuston and marine life in general, concerns have been raised that cleanup efforts could have an adverse effect on neuston due to potential co-accumulation of neuston and plastic at the sea surface. Here, we provide the most comprehensive assessment of neuston abundance in the eastern North Pacific Ocean and its relation to the distribution of floating plastic debris (0.05–5 cm in size) based on a first year-round survey. Our results reveal that neuston taxa inside the North Pacific Garbage Patch often show similar or lower abundances in areas with particularly high densities of floating plastic debris compared to the wider garbage patch. Targeting open-ocean cleanups on such plastic hotspot territories inside the garbage patch can therefore minimize interactions with neuston during cleanups, thus maximizing their net environmental gain. We further discover that neuston depicts substantial seasonal variability, which needs to be considered when assessing impacts on neuston.
Against Ceremonial Law
Authors: Gottlieb Michah
Published: May 2024

Spinoza asserted that “after the destruction of their state the Hebrews are not bound to perform ceremonies [… and] God requires nothing special of the Jews … beyond the natural law which binds all mortals.” Spinoza was alienated from Judaism and did not even regard himself as a Jew. He wrote the Theological-Political Treatise primarily, if not exclusively, for Christians. Yet in the eighteenth and nineteenth centuries, his analysis of the ceremonial law shaped conversations about modern Judaism. This chapter analyzes how David Friedländer deployed Spinoza’s and Moses Mendelssohn’s conceptions of the Jewish ceremonial law to argue against its continued authority. Friedländer did not simply return to Spinoza’s conception of Jewish ceremonial law but affirmed central features of Mendelssohn’s conception of it. The chapter concludes by pointing to how Friedländer’s arguments led to the emergence of something Spinoza never contemplated—a Reform Judaism free of binding ceremonial law.
Marx, Spinoza, and “True Democracy”
Authors: Field Sandra Leonie
Published: May 2024

It is common to assimilate Marx’s and Spinoza’s conceptions of democracy. This chapter assesses the relation between Marx’s early idea of “true democracy” and Spinozist democracy, both the historical influence and the theoretical affinity. Drawing on Marx’s student notebooks on Spinoza’s Theological-Political Treatise, the chapter shows that there was a historical influence. However, at the theoretical level, it argues that a sharp distinction must be drawn. Philosophically, Spinoza’s commitment to understanding politics through real concrete powers does not align with Marx’s anti-institutional conception of true democracy. And as a matter of social theory, the gap between civil society and the state which so troubles Marx is a development of modernity that has not entered Spinoza’s premodern field of view. Marx’s true democracy was also influenced by his study of Rousseau, and theoretically, it is just as close if not closer to Rousseau as to Spinoza.
Two Views of a View of a View of the Good
Authors: Shields Christopher
Published: May 2024

A survey of the reception of Aristotle’s arguments against Plato’s Form of the Good reveals a truly striking disarray: some critics take Aristotle to be wholly successful, believing that he has simply refuted Plato’s approach; others, equally distinguished, find his arguments jejune, hopeless, and almost incredibly bad. How could a man of Aristotle’s calibre, one asks, attack a view such as Plato’s—especially given that he himself adheres to many of its central commitments? So, complete disarray. This state of affairs bespeaks an unusual degree of scholarly and philosophical disagreement and thus recommends a careful reconstruction and consideration of each of Aristotle’s arguments in turn.
Remote Art and Aesthetics: An Introduction
Authors: Mortu Ancuta , Stejskal Jakub , Windsor Mark
Published: May 2024

This introduction to the special issue of the British Journal of Aesthetics, ‘Remote Art: Engaging with Art from Distant Times and Cultures’, presents the notion of art’s remoteness in the context of debates about inter-cultural diversity. It discusses the various aspects of remoteness, how it figures in the individual contributions to the issue, and suggests possible avenues for future scholarship.
Negative regulation of chitosan-induced stomatal closure by glutathione in Arabidopsis thaliana
Authors: Jahan Israt , Munemasa Shintaro , Nakamura Toshiyuki , Nakamura Yoshimasa , Murata Yoshiyuki
Published: May 2024

Chitosan (CHT) is a deacylated derivative of chitin and improves growth and yield performance, activates defensive genes, and also induces stomatal closure in plants. Glutathione (GSH) has significant functions in the growth, development, defense systems, signaling, and gene expression. GSH negatively regulates abscisic acid-, methyl jasmonate-, and salicylic acid-induced stomatal closure. However, the negative regulation by GSH of CHT-induced stomatal closure is still unknown. Regulation of CHT-induced stomatal closure by GSH in guard cells was investigated using two GSH-deficient mutants, cad2-1 and chlorina 1-1 (ch1-1), and a GSH-decreasing chemical, 1-chloro-2,4-dinitrobenzene (CDNB). The cad2-1 and ch1-1 mutations and CDNB treatment enhanced CHT-induced stomatal closure. Treatment with glutathione monoethyl ester restored the GSH level in the guard cells of cad2-1 and ch1-1 and complemented the stomatal phenotype of the mutants. These results indicate that GSH negatively regulates CHT-induced stomatal closure in Arabidopsis thaliana.
MoLPC2: improved prediction of large protein complex structures and stoichiometry using Monte Carlo Tree Search and AlphaFold2
Authors: Chim Ho Yeung , Elofsson Arne
Published: May 2024

Motivation

Today, the prediction of structures of large protein complexes solely from their sequence information requires prior knowledge of the stoichiometry of the complex. To address this challenge, we have enhanced the Monte Carlo Tree Search algorithms in MoLPC to enable the assembly of protein complexes while simultaneously predicting their stoichiometry.

Results

In MoLPC2, we have improved the predictions by allowing sampling alternative AlphaFold predictions. Using MoLPC2, we accurately predicted the structures of 50 out of 175 nonredundant protein complexes (TM-score ≥ 0.8) without knowing the stoichiometry. MoLPC2 provides new opportunities for predicting protein complex structures without stoichiometry information.

Availability and implementation

MoLPC2 is freely available at https://github.com/hychim/molpc2. A notebook is also available from the repository for easy use.
Flood ecology
Authors: Humphries Paul , Wohl Ellen , Agostinho Angelo A , Kopf R Keller , McCasker Nicole , Moyle Peter , Thorp James
Published: May 2024

Societal perceptions of river floods are typically negative because of the death and destruction they may cause, although scientists and natural resource managers have long recognized the critical ecological role of floods. Like fire and some other ecological disturbances, river flooding intersects many aspects of ecology and society. But unlike fire, flooding receives relatively little attention in the disturbance ecology literature. We call for more focused recognition of flood ecology as a discipline to help river science better inform societal perceptions through developing a better understanding of the ecological roles of flooding. We contend that the absence of a discipline of flood ecology has constrained progress in our understanding of how rivers function and that a formal conceptualization could help reveal the positive aspects of flooding. Finally, we propose a series of questions that we believe a discipline of flood ecology should address.