esa-sceva/satcom-chunk-collection huggingface dataset:
## 5 Results and Discussion
### Evaluation of Feature Selection Impact on Model Performance  
The influence of feature selection on model accuracy is highlighted in Figure 2, which provides a comparative analysis of MAPE values for SVM, XGBoost, and ELM-based models, both with and without feature selection algorithms. MLFS emerged as the most effective feature selection method, significantly reducing error rates for the SVM and XGBoost models. The improved performance is attributed to MLFS's ability to prioritize highly informative features while discarding redundant or less relevant variables, thereby enhancing the overall predictive capacity of the models. In contrast, the mRMR algorithm did not consistently yield positive results and, in some cases, increased the error rates for XGBoost models. This variability indicates that while feature selection is a critical step in model development, its effectiveness is contingent on the specific algorithm and data characteristics.  
ELM-based models also benefited from feature selection, with MLFS reducing MAPE values more effectively than mRMR. The consistent performance of MLFS across different models suggests its suitability for SMP forecasting tasks, where identifying key predictors is crucial for achieving high prediction accuracy. This underscores the importance of selecting an appropriate feature selection technique, as it can significantly influence model outcomes.
###### Abstract  
This paper presents a comparative study of the Vertex Block Descent (VBD) and Position-Based Dynamics (PBD) algorithms, focusing on their performance in physical simulation tasks. Unity, a versatile physics engine, served as the simulation platform for the experiments. Among various types of physical simulations of deformable objects, fluids, and cloth dynamics, cloth simulations were chosen for implementation with both algorithms. The experimental setup ensured identical parameters, including time steps and movement behavior, for both algorithms across scenarios involving hanging, object-to-object collisions, and self-collisions. The results indicate that while the performance difference in frames per second (fps) between the two algorithms is negligible for simulations with a small number of nodes, the VBD algorithm consistently outperforms the PBD algorithm as the node count increases. Furthermore, this study provides practical guidelines for maintaining real-time performance, detailing the maximum node count each algorithm can support, while sustaining a minimum threshold of 30 fps, which is necessary for real-time applications. The comparison was conducted using CPU-based computation to establish a baseline for future studies in GPU-accelerated environments, where parallel processing is expected to further highlight the performance advantages of VBD. Future work will extend this research by evaluating additional physical simulation models, including the Mass-Spring System and Extended Position-Based Dynamics (XPBD), and developing optimizations to enhance the efficiency and scalability of these algorithms.  
capable simulation; cloth simulation; physics-based simulation; vertex block descent; position-based dynamics
# The Feature Selection Effect on Missing Value Imputation of Medical Datasets
## 4 Experiments
### Results of Higher Dimensional Datasets  
Table 6 lists the classification results obtained with different combinations of feature selection methods and the MLP, KNN, and SVM imputation models for the high dimensional datasets with the 30% missing rate. The results are interesting, showing that for the arrhythmia dataset, which contains the largest number of features, performing feature selection by DT can allow the MLP, KNN, and SVM imputation models to produce slightly better imputation results than the baseline imputation models with feature selection.  
On the other hand, for the breast cancer dataset, the top two performances are based on GA+KNN and GA+SVM. This result indicates that performing feature selection does not necessarily have a positive effect on missing value imputation. However, based on the results of our experiments, a specific feature selection method and imputation model combinations can be recommended for future research, which is likely to outperform the baseline imputation models without feature selection.  
Table 7 shows the numbers of features selected by DT, GA, and IG. The results show that DT is a better choice for the higher dimensional datasets as large numbers of features can be filtered out, while combining DT with the imputation models can provide the best result in the arrhythmia dataset and reasonably good performance in the breast cancer dataset.
# Well-Distributed Feature Extraction for Image Registration Using Histogram Matching
###### Abstract  
Image registration is a spatial alignment of corresponding images of the same scene acquired from different views, sensors, and time intervals. Especially, satellite image registration is a challenging task due to the high resolution of images. In addition, demands for high resolution satellite imagery are increased for more detailed and precise information in land planning, urban planning, and Earth observation. Commonly, feature-based methods are applied for image registration. In these methods, first control or key points are detected using feature detector such as scale-invariant feature transform (SIFT). The numbers and the distribution of these control points are important for the remaining steps of registration. These methods provide reasonable performance; however, they suffer from high computational cost and irregular distribution of control points. To overcome these limitations, we propose an area-based registration method using histogram matching and zero mean normalized cross-correlation (ZNCC). In multi-spectral satellite images, first, different spectral responses are adjusted by using histogram matching. Then, ZNCC is utilized to extract well-distributed control points. In addition, fast Fourier transform (FFT) and block-wise processing are applied to reduce the computational cost. The proposed method is evaluated through various input datasets. The results demonstrate its efficacy and accuracy in image registration.  
image registration; area-based registration; feature-based registration +
Footnote †: journal: Applied Sciences
# Design of Dual Circularly Polarized Sequentially-Fed Patch Antennas for Satellite Applications
## 4 Array Prototype Fabrication and Measurements
The \(120^{\circ}\) phase shifts used to generate CP are then simply obtained by connecting the outputs of the two \(\Sigma-\Delta\) networks to the four scaled versions of patch feeding networks, already provided in Figure 2a. Finally, for the sake of completeness in Figure 8f a comparison of simulated and measured difference patterns is provided, that in this case shows a fair agreement. Figure 6: **(a)** Prototype of dual-CP sequentially-fed 2-by-2 antenna array. **(b)** Simulated co-polar (thin continuous black line with empty triangles for the cut plane at \(\phi=0^{\circ}\), thin blue dashed line with empty squares for the cut plane at \(\phi=90^{\circ}\)) and measured co-polar (thin continuous black line with empty triangles for the cut plane at \(\phi=0^{\circ}\), thin blue dashed line with empty squares for the cut plane at \(\phi=90^{\circ}\)) and simulated cross-polar (thick blue and black continuous lines with filled triangles for the cut planes at \(\phi=0^{\circ}\) and \(\phi=90^{\circ}\), respectively) gains of the array antenna at the central frequency \(f=2.2\) GHz. Figure 7: Block scheme of the connections between \(\Sigma-\Delta\) networks and the 2-by-2 array RH/LH CP ports.
## 4 Simulation Verification
### Normal Stable Conditions  
Figure 7 illustrates the DC-side voltage waveform, showing the stability and convergence of the voltage under four different control methods: LADRC, IVA-LADRC, SVA-LADRC, and VAV-LADRC. The analysis does not take into account variations on the grid side and load side.  
By comparing the test results shown in Figure 7, it can be observed that, under the VAV-LADRC method, the fluctuations and convergence speed of the DC-side voltage near normal conditions are significantly lower than those of the other three methods. Furthermore, the VAV-LADRC method demonstrates stronger robustness and more precise steady-state control when addressing voltage control issues, exhibiting superior control characteristics.  
Considering that the load is nonlinear in practical situations, harmonic distortion will occur in the current waveform. Figure 8 shows the current waveform after harmonic compensation at 0.15 s, once the system reaches stability. The compensated current values are presented in Figure 9.  
By performing a Fourier transform analysis on the steady-state period (0.15 s), it can be observed that the proposed improvement method significantly reduces the spikes in the waveform compared to traditional methods. Under the traditional LADRC method, the THD of the phase A current is 2.29%; under the IVA-LADRC control method, it is 2.01%; under the SVA-LADRC control method, it is 1.17%; and under the proposed AVA-LADRC method, the THD is reduced to 0.95%. The proposed method significantly reduces the harmonic content, particularly the higher-order harmonics, and effectively suppresses them, leading to a substantial decrease in THD.  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Parameters** & **Value** \\ \hline Nonlinear Load & 50 \(\Omega\) 300 mH \\ Sudden Nonlinear load & 50 \(\Omega\) 300 mH \\ Voltage Sag & 266 V \\ DC Link Voltage & 700 V \\ DC Link Capacitance & 3300 \(\mu\)F \\ Line Impedance & 10 mH \\ Inverter Resistance & 1 m\(\Omega\) \\ \hline \hline \end{tabular}
\end{table}
Table 1: _Cont._  
Figure 7: DC-side voltage waveform under normal states.  
Figure 8: Current waveform under stable states: (**a**) LADRC; (**b**) IVA-LADRC; (**c**) SVA-LADRC; (**d**) VAV-LADRC.  
Figure 9: THD of phase A current under stable states: (**a**) LADRC; (**b**) IVA-LADRC; (**c**) SVA-LADRC; (**d**) VAV-LADRC.
# Statistical Analysis of the Crosswalk Lighting Design Correctness
## 2 State of the Art  
In this section, we present the technical background of a lighting design, which is necessary for understanding computational problems appearing in this process. A typical implementation of the CEN 13201:2015 standard begins with assigning appropriate lighting classes to particular situations as it is defined in CEN 13201-1:2015 [1]. An assignment schema is based on analyzing a range of factors such as dominant road users (e.g., bicycles, motorized vehicles, pedestrians), allowed speed, presence of parked cars, number of road junctions per kilometer, traffic intensity, etc. It should be emphasized that a municipality which retrofits a lighting installation can impose classes different from those derived from a standard. It may occur in some critical areas such as a neighborhood with a school, a hospital or some other facility with increased risk of an accident or when a given area is the scene of numerous accidents. Once the proper classes are ascribed to all lighting situations, designers select a suitable setup (poles/arms/fxtures/luminous flux dimming) to comply with imposed classes. Those requirements are defined in CEN 13201-2:2015 [2] (see Table 1). Note that finding a well-tailored setup (also in terms of minimized investment costs and the future energy usage) is the most time-consuming part of project preparation. At this point, designers usually apply a generic \"template\" project covering a set of similar lighting situations. Such a template is not optimized, however, with respect to power usage. Yet another issue accompanying application of such \"templates\" arises in the case of pedestrian crossings; it leads to violating a lighting standard. Details of the problem are presented later in this paper.  
Figure 1: The reference lighting situation in a pedestrian crossing: **A**—streetlights; **B**—dedicated pedestrian crossing luminaires.
# CSNOMA: Carrier Sense Non-Orthogonal Multiple Access
## 4 Carrier Sense Non-Orthogonal Multiple Access (CSNOMA)
### Receiver Protection Mode  
One of the problem of CSNOMA is that the additional transmission is not guaranteed to succeed in the reception. To solve this problem, the receiver of the additional transmission behaves more conservatively. If the additional receiver overhears the RTS of conventional transmission node, the additional receiver sends out the CTS packet to its transmitter. If the additional transmitter receives this packet, it should shutdown to avoid collision with the noticed convention transmission.
# Phase Centre Corrections of GNSS Antennas and Their Consistency with ATX Catalogues
## 4 Results
stations ASG-EUPOS (BGS), EPN combined solutions 2013-2014, PPP (BGS) 2012-2014, and the post-processing of various short GPS observations (Trimble Business Centre 3.50--TBC) 2011-2016 (Table 1). The short GPS observations consist of various 4-h, 8-h, and 12-h sessions, the calculations of which were also checked in GNSS Solutions 3.80.3 and Geonet 2006 software [29]. The differences between them are negligible, which allows us to show a single (mean) value achieved by the most often-used software. The compatibility of the short observation post-processing (TBC, GNSS Solutions, or Geonet 2006) and spirit levelling (\(-6.2\) mm) results is noticeable when the more sophisticated solutions (e.g., PPP network solutions) give opposite values. The most contrary are values from PPP (BGS) 2012-14; the differences in the levelling result were as much as 20 mm. All of them used IGS08 antenna characteristics or only the elevation-dependent PCV model (GNSS Solutions). Surprisingly, such popular \"engineering\" software (e.g., TBC) achieved better results, comparable to spirit levelling, than the BGS (both short baseline calculations and PPP). The origin of the advantage of this type of software is not clear. It is probably that, for very close stations, the single baseline solutions, based only on the L1 frequency, give better results. Finally, the results of the height difference between the KRAW-KRA1 station were estimated by geometrical levelling, using a series of observations from 2011 to 2022 (Figure 9). Its most probable value is \(-6.2\) mm \(\pm\) 0.2 mm (Figure 10). \begin{table}
\begin{tabular}{c c c} \hline \hline
**Archive Data** & **\(\Delta\)h (mm)** & **\(\sigma\) (mm)** \\ \hline Warsaw University of Technology 2008–2011 (BGS) [34] & 5.5 & - \\ PAN Space Research Centre 2008–2011 (BGS) [35] & 7.3 & - \\ EPN Combined Solution 2013–2014 [29] & 11.0 & 1.5 \\ PPP (BGS) 2012–2014 [29] & 14.7 & - \\ Trimble Business Centre 2011–2016 [29] & \(-6.9\) & 0.5 \\ MUT Combined Solutions ig14.akx 2017 [36] & \(-0.5\) & 2.2 \\ MUT \({}^{*}\) Combined Solutions ig14.akx 2018–2022 & 1.1 & 2.7 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Archive values of differences between the KRA1–KRAW stations. Figure 9: Height difference between KRA1 and KRAW from the levelling from 2011 to 2022.
## 4 Outlook
### Accurate Simulation of Temperature Field  
The relationships among different factors involved in the simulation of the temperature fields of steel structures are shown in Figure 9. Too many simplifications and approximate values may lead to a great decrease in the accuracy of the temperature field simulation.  
Figure 8: Distribution of temperature sensors, strain gauges, GPS receivers and displacement transducers in the Tsing Ma Bridge [61].  
Figure 7: Locations of temperature and deflection sensors in the Zhijiang Cable-Stayed Bridge [134].  
Solar radiation absorptivity reflects the ability of a steel structure to absorb solar radiation energy [135], which is related to the structure surface coating's color, chemical composition, roughness, etc. Due to the lack of sufficient test data, solar radiation absorptivity is usually approximately determined on the basis of the color of the coating on the surface of the steel structure [37, 136]. However, even for different coatings of the same color, the difference in solar radiation absorptivity can be up to 67% [117]. The temperature fields of steel structures are very sensitive to solar radiation [137], and the accuracy of the temperature field simulation may be greatly reduced by adopting approximate value methods for solar radiation absorptivity. Therefore, a large number of solar radiation absorptivity tests should be carried out, according to the categories of steel structure surface coatings, and a detailed database needs to be established, which will not only be helpful for the thermal research of civil engineering, but will also be beneficial in aerospace engineering, vehicle engineering, environmental science, etc.  
There are many thermal boundary conditions, such as air temperature, wind speed and solar radiation intensity, that affect the temperature field of steel structures, and accurate thermal boundary conditions are key to ensuring the accuracy of temperature field simulations. In many studies, thermal boundary conditions have been calculated using simplified formulas, but these calculation results may differ greatly from the real thermal boundary conditions, whose variations are complex and difficult to accurately predict. Therefore, it is recommended that thermal boundary conditions obtained from a meteorological department or the measured data be used [138]. The long-term temperature field of steel structure can be simulated with multi-year meteorological data as the input for thermal boundary conditions, and this can be used as a basis for studying extreme temperature events and time-variance of temperature fields, which will provide opportunities for improving structural design methods and perfecting design specifications.
###### Abstract  
To address the issues of high attenuation, weak reception signal, and channel blockage in the current electric field communication of underwater robots, research on autonomous underwater vehicle (AUV) multi-node networking communication based on underwater electric field Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) channel was conducted. This article, first through simulation, finds that the Optimized Link State Routing (OLSR) protocol has a smaller routing packet delay time and higher reliability compared to the Ad Hoc On-Demand Distance Vector (AODV) protocol on underwater electric field CSMA/CA channels. Then, a 2 PSK underwater electric field communication system was established, and dynamic communication experiments were carried out between two AUV nodes. The experimental results showed that within a range of 0 to 3.5 m, this system can achieve underwater dynamic electric field communication with a bit error rate of 0 to 0.628%. Finally, to avoid channel blockage during underwater AUV multi-node communication, this article proposes a dynamic backoff method for AUV multi-node communication based on CSMA/CA. This system can achieve dynamic multi-node communication of underwater electric fields with an error rate ranging from 0 to 0.96%. The research results have engineering application prospects for underwater cluster operations.  
underwater communication; electric field; multi-node networking; CSMA/CA; AUV Article Research on AUV Multi-Node Based on Underwater Electric Field CSMA/CA Channel  
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# GPS + BDS Network Real-Time Differential Positioning Using a Position Domain Estimation Method
## 2 Materials and Methods
### Position Estimation for User
#### 2.2.2 An Improved Algorithm in the Position Domain
The accuracy of the carrier phase and pseudorange observations and the elevation-dependent weighting function are the same as those in the traditional range-domain algorithm. In this way, the stochastic model can be determined. The position estimation results and the corresponding covariance matrix can be computed using the following formula  
\[\left\{\begin{array}{l}\mathbf{\hat{X}}_{k}\!\!=\mathbf{\hat{X}}_{(k/k-1)}\!+\!\mathbf{J }_{k}\!\left[\mathbf{L}_{k}\!\!-\!\!\mathbf{B}_{k^{\prime}}(\hat{X}_{(k/k-1)}\!\!-\!\bm {X}_{0k})\right]\\ \mathbf{D}_{\mathbf{X}_{k}}=(\mathbf{E}\!-\!\mathbf{J}_{k}\!\cdot\!\mathbf{B}_{k})\!\cdot\!\mathbf{D}_{ \mathbf{X}_{(\(\hat{\mathbf{X}}_{(k/k-1)}\) is the predicted position vector, \(\mathbf{J}_{k}\) is the gain matrix, \(\mathbf{E}\) is the identity matrix, \(\mathbf{D}_{\mathbf{X}_{(k/k-1)}}\) is the covariance matrix of \(\hat{\mathbf{X}}_{(k/k-1)}\), \(\mathbf{D}_{\mathbf{A}_{k}}\) is the covariance matrix of the observation noise, \(\mathbf{D}_{\mathbf{X}_{k-1}}\) is the covariance matrix of \(\hat{\mathbf{X}}_{k-1}\) and \(\mathbf{D}_{\mathbf{\Omega}_{k-1}}\) is the covariance matrix of \(\mathbf{\Omega}_{k-1}\).
# Halophyte Plants and Their Residues as Feedstock for Biogas Production--Chances and Challenges
## 5 Halophyte Composition
### Lignin Content  
The lignin content, determined as the residual part of the lignocellulosic fraction of the halophyte plant after sugar extraction, has generally been found to be notably lower in the aerial fraction of naturally grown halophytes compared to cultivating under controlled conditions of salinity and fertilizer grades ([PERSON] et al., 2018; [PERSON] et al., 2018). For instance, [PERSON] et al. (2018) reported a higher Klason lignin content, of 10-17%, in the stems of _Salicornia bigelovii_ as compared to the seed spikes (pods), 5-9%, when cultivated under different salinity:fertil concentration ratios. High salinity was correlated to lower lignin content, particularly in the pod fractions of _Salicornia bigelovii_. It was observed that stems contained significantly more lignin than pods at higher salinity ([PERSON] et al., 2018). Inconsistently, seedlings of _Salicornia bigelovii_ grown under 40 g L\({}^{-1}\) NaCl and 1-2 N g m\({}^{-2}\) contained 6.8% lignin, well within the range of lignin content of naturally grown halophyte biomass ([PERSON] et al., 2018).