esa-sceva/satcom-chunk-collection huggingface dataset:
# Passive Location for 5G OFDM Radiation Sources Based on Virtual Synthetic Aperture
## 2 Theoretical Analyses of Typical Source Localization Methods
### Direction of Arrival (DOA)  
DOA systems use the direction information to realize source localization. The direction information is usually from phase interferometer systems or antenna arrays in most systems.  
For a phase interferometer system, the basic principle is using the phase difference generated by the signal on different receiving antennas to obtain the direction of the source, then system location combined with two-dimensional DOA estimation obtained by a two-dimensional interferometer is used to obtain the source location.  
The wave path difference of two antennas \(\Delta d\) can lead to phase difference \(\Delta\phi\):  
\[\Delta\phi=\frac{2\pi}{\lambda}\Delta d,\Delta d=d\sin\theta \tag{1}\]  
where \(d\) is the baseline length and \(\theta\) is the incident angle. Since the phase difference measured by a phase interferometer is ranged \((-\pi,\pi)\), only when wave path \(\Delta d<\lambda/2\), is there no ambiguity in direction estimation, and the direction of the source can be directly estimated by the phase difference measured by the interferometer. When \(\Delta d>\lambda/2\), there is ambiguity that needs to be solved to obtain the correct direction of the source [24].  
To solve phase ambiguity and ensure direction estimation accuracy, multiple antenna structures are usually designed, such as the long and short baseline method, which uses a short baseline to solve ambiguity and a long baseline to ensure high accuracy; the virtual baseline method, which can obtain the phase difference of a short baseline by subtracting the phase difference between two different baselines to resolve the ambiguity and long baseline can ensure high accuracy; or using a rotating interferometer to solve ambiguity and reduce the number of baselines [25].  
For antenna array DOA localization systems, a two-dimensional array is designed to obtain two-dimensional DOA estimation, antenna array DOA estimation can be realized by CBF, MUSIC or MLE [6].  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Symbol** & **Definition** & **Symbol** & **Definition** \\ \hline \(a\) & Variable & rect\(\{\cdot\}\) & Rectangular function \\ \(a\) & Vector & exp\(\{\cdot\}\) & Exponential function \\ \(A\) & Matrix & \(\delta(\cdot)\) & Impulse function \\ \((\cdot)^{T}\) & Transpose & \(|\cdot|\) & Absolute value \\ \((\cdot)^{*}\) & Conjugate & \(\otimes\) & Convolution \\ \(\lambda\) & Estimated value & O(\(\cdot\)) & Big-oh, complexity symbol \\ \hline \hline \end{tabular}
\end{table}
Table 1: Notations.  
Single-satellite DOA method is not limited by signal form and can be applied to any bandwidth signal. However, to obtain high accuracy, a complex antenna structure is needed, so the location performance is relatively poor due to the limitation of the mobile platform [3].
# Improving Computational Efficiency in Crowded Task Allocation Games with Coupled Constraints
## 1 Introduction  
Application of multi-agent systems have often been considered for large-scale problems that are otherwise difficult or impossible to solve with only a single agent. Despite the difficulties in coordinating multiple agents, systems with multiple heterogeneous agents have often been preferred over a single omnipotent agent and the belief that the collective effort of multiple agents is superior to that of an individual can be attributed to concepts of robustness, parallelism, and cost issues.  
Therefore, challenges in managing a multi-agent system have been extensively studied with the proposal of a variety of approaches and algorithms [1; 2; 3; 4; 5; 6; 7; 8] which are applicable to a multiplicity of systems ranging from military operations to resource distribution [2; 6; 8; 9; 10]. One notable approach is the introduction of game-theoretic framework in multi-agent systems. With the continuous development of intelligence in autonomous systems, concerns of social awareness and acceptability [11] have been frequently raised. In traditional systems which are designed to achieve near-optimal solutions, agents are often programmed to be greedy and to seek maximum rewards for their actions leading to a competitive environment within the system, such that an agent may act in a manner that jeopardize the overall objective of the group for their own good. This concern leads to the adaptation of a game-theoretic framework which provide each individual agent freedom over its actions while at the same time, ensure that the solutions proposed by the collective action are socially acceptable and stable despite the players being self-regarding. As such, many game-theoretic models have been proposed to meet the requirements of different application scenarios and equilibrium selection algorithms ranging from constraint optimization [2; 12] to learning [13; 14; 15] have been designed and shown to be feasible.  
In this paper, we consider a game-theoretic framework for the coupled-constraint task allocation problem which is highly applicable to situations concerning military and disaster relief operations where the number of tasks is, generally, significantly large and are frequently spatially and temporally correlated. In such emergency situations, higher levels of emphasis are placed on the speed ofdecision-making rather than the optimality of the decisions, and as such, the main objective of this paper is to propose a game-theoretic model that enables autonomous multi-agent systems to make quick decisions that are feasible despite possibly having lower levels of optimality. We build on our previous work [16] which considers a game-theoretic framework for spatially constrained task allocation environments, taking into account additional temporal constraints and, at the same time, propose some modifications to the Distributed Stochastic Algorithm to allow quicker convergence in congested problems.
# Battery Surface and Edge Defect Inspection Based on Sub-Regional Gaussian and Moving Average Filter
## 4 Experiments and the Analysis of Results  
A total of 600 battery samples with \(8192\times 10,240\) pixels are divided into 5 groups and applied in our defection system to evaluate the effectiveness of the proposed algorithm. Figure 13 shows the experimental results of the proposed processing algorithm based on sub-regional Gaussian and MAF compared with other processing methods. Tables 1 and 2 illustrate critical data to demonstrate the superiority of the proposed algorithm. Table 1 shows the comparison of partition and traditional unpartitioned detection results, it means that the traditional method is to process horizontally or vertically on the whole picture directly, while the partition processing takes into account the uneven illumination distribution of the edge of the image, the vertical processing at the edge, and the horizontal processing inside image. Table 2 illustrates the accuracy rates and detection time with different concave and convex defect inspection methods, because there is almost no research on the surface defects of the battery, battery surface images we acquired are applied into the current popular metal surface defect detection algorithms, and the performance index is analyzed. Both algorithms were developed with MATLAB (Version R2017b, MathWorks Inc., Natick, MA, USA) and Microsoft Visual Studio 2013 and operated in a computer with Windows system (CPU 3.6 GHz Intel Core i7, Memory 8 GB).  
Figure 13: The inspection results of defects for concave and convex based on sub-regional Gaussian and MAF, where \(N=512\). **(a)** Inspection result of defects for concave and convex on image 1; **(b)** Inspection result of defects for concave and convex on image 2; **(c)** Inspection result of defects for concave and convex on image 3; **(d)** Inspection result of defects for concave and convex on image 4.
# The State of Ethereum Smart Contracts Security: Vulnerabilities, Countermeasures, and Tool Support
## 4 Smart-Contracts Vulnerabilities and Countermeasures
### Vulnerabilities and Countermeasures
#### 4.2.9 Timestamp Dependence  
Blocks in Ethereum are created in the mining process in which the miner has a certain degree of arbitrariness to decide the timestamp of the whole block. The time range used to be 900 s, but it was narrowed down to a few seconds after an upgrade [84]. All the transactions recorded on the block have the same timestamp. Since the miner can decide timestamps on transactions, certain applications that function correctly under time constraints are susceptible to malicious miners. The timestamp is also used as a seed when generating random numbers. Attackers may manipulate the timestamp of a block to trigger expected behaviours from smart contracts [28].  
_Countermeasures_. [PERSON] and [PERSON] [74] mention that using block.number is a better choice than block.timestamp. As block generating speed is usually 10 s, there will be 60,480 blocks, approximately, in one week. By specifying a future block number, a time estimation comes with this future block.number.
# Influence of Altitude on Phytochemical Composition of Hemp Inflorescence: A Metabolomic Approach
## 3 Materials and Methods
### HS-SPME and GC-MS Analysis for Terpenes Examination  
Complete analytical technique was provided in detail in our recently published article [12; 24; 25]. In brief, 100 mg of inflorescence powder was put into 20 mL glass vials along with 100 \(\upmu\)L of the IS (4-metil-2-pentanone, 20 mg/mL in 2-propanol). A cap with a silicon/PTFE septum (Supelco, Bellefonte, PA, USA) was used to close the vial, which was then kept in the temperature block (37 \({}^{\circ}\)C), (CTC Analytics, Zwingen, Switzerland). At the end of the sample equilibration time (30 min), a conditioned (60 min at 280 \({}^{\circ}\)C) SPME fiber was subjected to the sample for 120 min using a CombiPAL system injector autosampler (CTC Analytics, Zwingen, Switzerland).  
Analyses were performed with a Trace GC Ultra coupled to a Trace DSQII quadrupole mass spectrometer (MS) (Thermo-Fisher Scientific, Waltham, MA, USA) equipped with an Rtx-Wax column (30 m \(\times\) 0.25 mm i.d. \(\times\) 0.25 \(\upmu\)m film thickness) (Restek, Bellefonte, PA, USA). The oven temperature program was: from 35 \({}^{\circ}\)C, held for 8 min, to 60 \({}^{\circ}\)C at 4 \({}^{\circ}\)C/min, then from 60 to 160 \({}^{\circ}\)C at 6 \({}^{\circ}\)C/min and finally from 160 to 200 at 20 \({}^{\circ}\)C/min. Helium was the carrier gas, at a flow rate of 1 mL/min. The MS was operated in electron impact (EI) ionization mode at 70 eV, _m/z_ range of 35-350. An alkanes mixture (C8-C22, Sigma R 8769, Saint Louis, MO, USA) was run under the same chromatographic conditions as the samples to calculate the Kovats Retention Indices (RI) of the detected compounds [27; 45]. Compounds were recognized by comparing with authentic standards or by using the Kovats retention indices in combination with the literature and via the National Institute of Standards and Technology (NIST) MS spectral database. The semi-quantitative evaluation was achieved using the internal standard procedure and the results were expressed as \(\upmu\)g/g IS equivalents.
# Gearbox Fault Diagnosis Based on Multi-Sensor and Multi-Channel Decision-Level Fusion Based on SDP
## 5 Conclusions  
The multi-channel decision-level fusion algorithm that was based on SDP analysis and the VGG16 fault diagnosis model was proposed for the research point of the poor robustness of the traditional single-channel vibration signals in the comprehensive monitoring of gearbox fault states in the present study. The multi-channel sensor has been proven to be able to collect the signal source comprehensively in order to compensate for the problem of low accuracy of the gear fault diagnosis that was caused by insufficient data sources. The experimental results showed that, before fusion, the multi-channel diagnosis results per sensor were 3.01%, 16.7%, and 5.17% higher than the single-channel diagnosis results, respectively, in case of fewer data sources. After fusion, the difference between the single-channel and the multi-channel fault diagnosis accuracy was not significant in the presence of sufficient data sources. It can, therefore, be concluded that the number of data sources has a great influence on the fault diagnosis results, and the more data sources there are, the higher the accuracy is. Hence, the research results are of great significance for gearbox gear teeth pitting status identification.  
[PERSON] conceived this research; [PERSON] and [PERSON] performed the calculations; [PERSON], [PERSON] and [PERSON] prepared the original draft; editing and review of this article was completed by [PERSON]; [PERSON] and [PERSON] were responsible for overseeing the progress and visualization of the article. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the National Key R&D Program of China (NO. 2020 YFB2010103), the National Natural Science Foundation of China (No. 52075062), Ministry of Industry and Information Technology's Industrial Foundation Reconstruction and Manufacturing High-quality Development Project (No. TC210H02V), and the Graduate Student Innovation Project of Chongqing (No. CYS21465).  
The authors declare no conflict of interest. In addition, the funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.
# A Cyber-Physical System for Wildfire Detection and Firefighting
## 3 Materials and Methods
### Notification Systems Node  
The Notification Systems node comprises two serverless functions managed through the Nuclio platform. The two functions are capable of sending a fire alert to all connected devices, such as the UAV and wildfire detection system. The system is also connected to an IFTTT web-based service that uses a Webhook for HTTP requests to a specified URL with parameters and authentication details. The combination of wehooks and IFTTT allows the automation of various tasks and the creation of custom workflows. In our case, it is able to send messages to a Telegram chatbot. This system is vital because it provides real-time alerts to the firefighter operator, ensuring that they are constantly informed and able to respond quickly. The scalability of the Notification System allows an easy way to upgrade the services and the automated task, but also the flexibility to be integrated into other existing alerting systems.
# Ferroelectric Materials: A Novel Pathway for Efficient Solar Water Splitting
## 4 Ferroelectric Materials for Photoelectrochemical (PEC) Water-Splitting Devices
### Ferroelectric-Based Materials in Photocathodes for Hydrogen
#### 4.2.1 Ferroelectric Oxide Perovskites
In addition, it is reported that metal doping is an effective strategy for enhancing the p-type nature of the ternary oxides [71]. In particular, LFOs have been shown to exhibit both cathodic and anodic photocurrents depending on the specific conditions [72]. Although sophisticated fabrication techniques such as PLD can improve the PEC response of LFO photocathodes, the high cost and challenging technical requirements are still primary impediments. Recently, novel research in the preparation of nanostructured LFO thin films using an inexpensive spray-pyrolysis method resulted in outstanding results [73]. The fabricated photoelectrode yielded a photocurrent density of 0.16 mA/cm\({}^{2}\) at 0.26 V versus RHE, which is by far a more drastic enhancement compared to the PLD technique [63]. Interestingly, this is the first time that spontaneous hydrogen generation has been achieved using PEC water splitting without any external bias voltage using LFO as a single photoelectrode material. Admittedly, LFO is a potential candidate for a photocathode because of its stable characteristics in aqueous solutions, as well as its very positive onset potential values. However, further research should be performed to improve the slow kinetics of charge transfer, which favors recombination at surface trap states.
## 6 Conclusions  
This study applied the Ensemble Kalman Filter (EnKF) data assimilation technique to calibrate the constants of the RNG k-\(\epsilon\) turbulence model, aiming to improve the predictive accuracy of gas flow through plunger lift systems. The integration of experimental observations with numerical simulations enabled significant reductions in prediction errors. Specifically, the mean square error (MSE) for the rectangular and circular arc plungers decreased from 60.67 and 61.48 to 7.12 and 7.20, respectively, demonstrating the method's robustness and adaptability to different plunger geometries.  
In addition to quantitative improvements, data assimilation revealed critical insights into the flow characteristics within the plunger gap. Notably, changes in the circumferential flow structures and turbulence intensity indicated that conventional models may overestimate sealing performance. The recalibrated model better captured these complex features, providing a more realistic representation of the underlying physics.  
The findings highlight the effectiveness of data assimilation not only in enhancing model fidelity but also in improving the understanding of gas-liquid interaction mechanisms in narrow annular flows. This approach provides a new methodology and perspective for optimizing the geometric design of plunger slot structures, allowing for better evaluation of sealing performance and flow behavior under varying operational conditions.  
From an application standpoint, the calibrated turbulence model offers practical guidance for the structural optimization of gas-lift plunger's, particularly in the design  
Figure 15: Dissipation rate of turbulent kinetic energy contour maps of the same cross section.  
and assessment of different sealing slot types. Future research will focus on extending the assimilation framework to incorporate multi-parameter uncertainty quantification and to explore more diverse plunger configurations in low-pressure gas wells.  
Methodology and Field Experiments: J.Z. and Y.S.; Data Analysis and Original Draft Preparation: J.Z. and Y.S.; Review and Editing, Project Management, and Funding Acquisition: J.Z.; Resources and Supervision: Y.X.; Manuscript Organization and Experiment Coordination: Y.Y. and J.W. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Not applicable.  
The datasets generated during and/or analyzed during this current study are available from the corresponding author upon reasonable request.  
The authors declare no conflicts of interest.
## 2 Results and Discussion
### Effect of Nanoparticles Mg NP/GW and GW NPs on Sinapis alba Seed Germination  
The impact of Mg NP/GW and GW NP applications on _S. alba_ seed germination indicates that at lower concentrations of Mg NP/GW, seed germination and seedling growth increased, while at higher concentrations, these processes were inhibited (Table 2). Specifically, seeds treated with GW (0.5 g/L) exhibited a seed germination rate of 96.67%, whereas the lowest germination percentage was observed in the GW (5.0 g/L) treatment, with only 46.67% germination. Similarly, the highest concentration (5.0 g/L) of Mg NP/GW resulted in significantly lower germination percentages, with only 46.67% germination. The maximum seed germination rate was observed at the (0.5 g/L) concentration of Mg NP/GW, reaching 100%.  
Overall, the germination percentage declined as NP concentrations increased, indicating an inhibitory effect with higher NP concentrations. These findings suggest that increasing NP concentration leads to decreased seed germination (Table 2). Notably, the control treatment exhibited a 100% germination rate [40]. The lowest concentration of Mg NP/GW (0.5 g/L) demonstrated a significant increase in germination percentages and seedling growth, indicating a potential positive effect. However, the mechanism underlying this positive effect requires further investigation [41; 42]. Conversely, the highest concentration of Mg NP/GW (5.0 g/L) resulted in a significant decrease in germination percentages, suggesting a potentially toxic effect on the seeds. This toxicity could stem from various factors, including altered physiological processes or interference with cellular structure [43; 44].  
Furthermore, the results suggest that the growth-promoting agent GW, at a concentration of 0.5 g/L, can significantly enhance seed germination. This implies that GW may possess properties conducive to seedling development, particularly when combined with the optimal concentration of Mg NP/GW [45]. Further exploration is warranted to elucidate the underlying mechanisms and potential applications of these effects.
## 1 Introduction
In particular, there is a lack of quantitative analyses on the differences between the measurements of multiple types of visibility meters and the manual observations obtained at the same location. Transmissometers or forward-scatter visibility meters are currently installed at most airports in China. The application of instrument-measured visibility in aviation operations is becoming increasingly extensive, and there is an urgent need for a scientific basis for selecting suitable visibility meters during the construction of new airports. Therefore, it is necessary to evaluate the performance of different types of visibility meters and compare the differences between instrumental and manual visibility observations at Xiamen Airport. In this study, we used the records of transmissometers and a forward-scatter visibility meter, as well as visibility measurements obtained through manual observation during the same period at Xiamen Airport from 2015 to 2020, to compare the data collected using different types of visibility meters with those obtained through manual observation. We analysed the distribution of the difference between the instrumental and manual results and the possible reasons and also assessed the performance of different types of visibility meters under the influence of relative humidity (RH), aiming to provide technical support for reasonably planning the deployment of visibility meters at airports.
## 1 Introduction  
Growing requirements from investors in the mining and processing industry, especially regarding its efficiency and effectiveness, have contributed to the development and design of technology to transport raw mining materials using bucket conveyors [1]. After achieving the required system reliability, the attention of designers and users focuses primarily on reducing operating costs by implementing advanced control and driving systems solutions. The developed solutions are intended, on the one hand, to reduce electricity consumption and, on the other hand, to extend the life of the conveyors.  
In hard coal processing plants, bucket conveyors are used to transport and dewater materials in the beneficiation process in water pulsating jigs. In these situations, where the coal feed to be enriched has a small amount of waste product and/or semi-finished products, the conveyors operate for long times with low loads. Reducing the speed in such situations will not only reduce electricity consumption, but will also slow down wear of the conveyor. Less mechanical wear is observed when the conveyor operates at higher loads and lower speeds [2, 3]. Bucket conveyor maintenance costs, which include the costs of replacing wearing parts as well as energy consumption costs by the electric motor, make it necessary to automate the operation of these devices and adapt their efficiency appropriately to the current demand [4]. A conveyor control system is presented, which is controlled by an automatic control system with a Smith predictor. This research presents a method for optimizing this algorithm using a fuzzy controller. These activities are part of the trend of using fuzzy logic controllers in the control systems of machines operating in jig beneficiation nodes.