esa-sceva/satcom-chunk-collection huggingface dataset:
## 4 Experimental Setup and Results Analysis
### Experimental Results
#### 4.5.2 The Effect of Multihead Attention  
Our investigation further assessed the impact of varying attention head counts on the outcomes. As illustrated in Figure 2(b), the model exhibited optimal performance with a duo of attention heads. Multiple attention heads allow the exploration of different feature subspaces, which can improve the generalization performance of graph neural networks.  
Figure 3: Influence of different hyperparameters on the results.  
Figure 2: Overall experimental accuracy.  
When pursuing multihead attention, the computation of each head can be parallelized, giving the algorithm a special advantage. Yet, with an escalating count of attention heads, the predictive outcomes do not enhance; instead, they exhibit a steady decline, indicating that information interference reaches saturation.
# Spaceborne GNSS-R Observation of Global Lake Level: First Results from the TechDemoSat-1 Mission
## Data and Methods  
### Data Description  
The TDS-1 Level 1b data are used to investigate the global lake level since this is the product most publicly available (rather than L0 data using which could derive better accuracy of lake level [15]) at the MERRByS (measurement of Earth reflected radio-navigation signals by satellite) website. The data set used in this study covers a 3 year period from 2015 to 2017. The main observation from the TDS-1 L1b data is the delay-Doppler maps (DDMs). DDM is the correlation power sampled in delay and Doppler space by correlating the reflected signal with a local generated replica [17]. The TDS-1 DDMs are made of 128 delay pixels by 20 Doppler pixels, with a Doppler resolution of 500 Hz and a delay resolution of 244.3942 ns [16].  
Two data sets, i.e., the CyroSat-2 level 2 GDR data set and the Hydroweb data set [18] are used to validate TDS-derived lake level. Both of the two data sets can provide centimeter-level altimetry accuracy. The CryoSat-2 spatial data is referenced to the WGS84 Ellipsoid, and the surface height is processed through instrument correction, transmission delay correction, geometric correction and geophysical correction [19]. The Hydroweb data set collects time series of daily water levels of more than 150 inland lakes and rivers around the world. The water levels from Hydroweb are derived using altimetry satellites such as Jason and Envisat. The data source for each lake used in this study is attached in the supplementary materials, Table S1. The reference surface of Hydroweb data is the GRACE gravity model 02C (GGM02C), which is a high-resolution global gravity model (i.e., a kind of geoid).  
Given that the reflected waveform from surface with elevations over 3000 m is not contained within the DDM window [6], in this study, we investigate 351 lakes globally with areas greater than 500 km\({}^{2}\) and elevations lower than 3000 m (Figure 1). Surface area and mean elevation of these lakes are derived from the Global Lakes and Wetlands Database (GLWD) [20]. The 500 km\({}^{2}\) threshold is determined to ensure that, (1) a specific lake is large enough to have sufficient specular points located on it within a certain time window, and (2) there are sufficient lake samples for correlation analysis on a global scale.
# Application of a MEMS-Based TRNG in a Chaotic Stream Cipher
## 5 Cryptanalysis
### Sensitivity Dependence on the Plaintext  
Our cryptosystem, like most of the stream ciphers, does not present a sensitivity dependence on the plaintext since a single bit change on the plaintext only changes one bit of the ciphertext. This makes the system vulnerable to some attacks, such as a differential known plaintext attack, if several messages are encrypted using the same key. By using a MEMS inertial sensor to generate true random keys, this problem is avoided.  
Figure 12: NIST test results for a sequence generated by (**a**) The STM algorithm; (**b**) The STM-LFSR algorithm. The tests numeration is the same as in Table 1.
## 4 Results and Discussions
### Effect of Constraint Conditions at the Pile Tip
#### 4.3.2 Earth Pressure and Subgrade Reaction  
Figure 19 demonstrates the variations of the non-dimensional earth pressure and subgrade reactions with depth on the negative battered piles (\(\beta=-20^{\circ}\)) under different constraint conditions at the pile tip (free tip and fixed tip). As expected, the non-dimensional earth pressure and subgrade reaction under fixed tip boundary conditions would be less than those under free tip boundary conditions. In addition, the constraint condition at the pile tip would little affect the location of the maximum non-dimensional earth pressures. However, the locations of the maximum non-dimensional subgrade reactions and zero non-dimensional subgrade reactions would move downward while the restriction on the pile tip is released to the free tip boundary condition.  
For an intuitive illustration of the influence of the pile tip constraint conditions on pile performance, Table 6 summarizes the maximum responses (including the maximums of pile deflections, bending moment, earth pressure, and subgrade reaction) under different pile tip constraint conditions in the case of \(\beta=-20^{\circ}\).  
Figure 19: Non-dimensional earth pressure and subgrade reaction profiles under different constraint conditions at the pile tip: (**a**) earth pressure; (**b**) subgrade reaction.  
Figure 18: Variations of non-dimensional pile deflections and bending moments with depth under different constraint conditions at the pile tip: (**a**) pile deflection; (**b**) bending moment.
# Machine Learning in Beyond 5G/6G Networks--State-of-the-Art and Future Trends
## 4 Beyond 5G/6G Applications and Machine Learning
### Supervised Learning
#### 4.1.6 Security  
In [58], the authors use decision tree algorithms to boost trust management using eXplainable Artificial Intelligence (XAI) for intrusion detection. Simple decision tree algorithms are applied to split the sub-choices for the intrusion detection system (IDS), which resemble a human approach to decision-making.Results show that the accuracy of the proposed approach is comparable with state-of-the-art algorithms. The authors in [59] used a supervised-based LSTM algorithm for intrusion detection model. They applied 6 different optimizer to investigate the performance of the model and the results show that LSTM model with Nadam optimizer can achieve an accuracy of 97.5%, which outperforms conventional approaches. In [60], the authors propose a supervised CNN-based method to classify and detect malware traffic, with classification accuracy of up to 99.4%.
## 2 CFD Modelling
### Different Hub Geometries Used in the Numerical Analysis  
As seen in Figure 4A,B, in the vicinity of the impeller eye region, the flow in a standard hub-less base design abruptly switches from axial to radial.  
The main goal of the current analysis is to reduce the areas of stalling inceptions close to the impeller's inlet region. This is achieved by offering hub designs that are either  
Figure 4: Hub-less arrangement’s geometric model, (**A**) Side view, (**B**) Isometric view.  
Figure 3: The validation curve for operating characteristics [17].  
hemispherical or elliptical, as depicted in Figures 5 and 6, respectively. To investigate the effectiveness of the hub in each scenario compared to the hub-less base configuration, numerical calculations are carried out separately for hemispherical (Figure 5A) and ellipsoidal (Figure 6A) designed hubs. The equivalent numerical models of the inlet region with a hub are shown in Figures 5B and 6B. To enable the hub's rotation with respect to the impeller, CFD software (2021 version) provides it with a \"moving wall boundary condition\".  
The geometry employed for the variation of ellipsoidal hub configurations is the length of the hub in the axial direction, whereas for hemispherical hub configuration it is the hub radius. For the hemispherical and ellipsoidal hub models, these two parameters  
Figure 5: The hemispherical hub configuration’s geometrical setup, (**A**) Side view, (**B**) Isometric view.  
Figure 6: The ellipsoidal hub configuration’s geometric configuration, (**A**) Side view, (**B**) Isometric view.  
are non-dimensional in terms of the entrance radius of the duct and are known as the spheroidal hub ratio and the ellipsoidal hub ratio, respectively.  
\[\text{Spheroidal hub ratio, }R_{\text{s}}=\frac{r_{h}}{r} \tag{7}\]  
\[\text{Ellipsoidal hub ratio, }R_{E}=\frac{l_{h}}{r} \tag{8}\]  
In the analysis, the parametrically changed values of the spheroidal hub ratio and ellipsoidal hub ratio are listed in Table 3. The hemispherical hub geometry's radius is optimized to produce the ellipsoidal hub's meridian height (d), as further discussed in Section 3.1.
## 5 IPv6 in Networking
### Enhanced Security Features  
IPv6 includes built-in security features such as mandatory support for IPsec at the network level. IPsec provides authentication and encryption to secure the confidentiality and integrity of data transmitted across the network. These security mechanisms are particularly important in load-sharing and link-failure scenarios, where secure data transfer and smooth network transitions are critical to maintaining network reliability and confidentiality. IPv6's emphasis on security enhances the overall dependability of load-sharing and link-failure systems, establishing a more secure foundation for modern networking environments.
## 2 Materials and Methods  
In the experiment, we used double-side polished FZ \(p\)-type Si wafers (Institute of Electronic Materials Technology, Warsaw, Poland) with the resistivity of 5000 \(\Omega\)-cm, thickness of 275 \(\upmu\)m, and orientation of (100). Before TiO\({}_{2}\) deposition, Si wafers were cleaned in sequence by acetone to remove the organics and by 5% hydrofluoric acid to remove the native oxide. Then, wafers were rinsed in deionized water and dried with N\({}_{2}\) gas. Right after the cleaning, Si substrate was placed in the reaction chamber and then the chamber temperature was raised to 200 \({}^{\circ}\)C for the ALD deposition [28].  
For the process, we employed TiCl\({}_{4}\) and H\({}_{2}\)O as the reactants and Ar (99.999%) as the purging gas. One cycle (one monolayer) of TiO\({}_{2}\) growth was 0.066 nm in thick and included eight steps, i.e., TiCl\({}_{4}\) reactant, pump-down, Ar purge, pump-down, H\({}_{2}\)O reactant, pump-down, Ar purge, and pump-down. Due to the self-limiting growth of ALD, we grew four different thicknesses of TiO\({}_{2}\) thin films by controlling the cycle numbers (125, 250, 530, and 1000 cycles).  
For the characterization of TiO\({}_{2}\) thin films, we used the Tecnai G2 TEM (FEI Company, Hillsboro, OR, USA) to study the crystallinity, phases and thickness of TiO\({}_{2}\). The samples for TEM were prepared by Dual Beam-Focused Ion Beam system. SIMS of Cameca IMS 6F (AMETEK S.A.S., Elancourt, France) was used to analyze the depth profiles of oxygen, silicon and hydrogen. Jobin Yvon U1000 Raman spectroscopy (HORIBA, Kyoto, Japan) equipped a laser with wavelength of 532 nm was employed to estimate the crystalline size of 66 nm TiO\({}_{2}\) films. [PERSON]'s spectroscopic ellipsometry (J.A. Woollam Co., Lincoln, NE, USA) was used to study the optical properties and homogeneity of TiO\({}_{2}\) films along the growth direction. To study the silicon surface passivation, the effective minority carrier lifetimes were obtained by Sinton's WCT-120 (Sinton Instruments, Boulder, CO, USA) in quasi-steady-state photo-conductance (QSSPC) mode with a light bias for high resistivity Si wafers [29; 30].  
For the passivating-contact applications of c-Si solar cells, we go further to discuss the reflectivity and Si surface passivation of TiO\({}_{2}\)/SiN\({}_{x}\) stacks composed of 8-nm-thick TiO\({}_{2}\) and 72-nm-thick SiN\({}_{x}\). The capping layers, i.e., SiN\({}_{x}\) film, were grown by plasma-enhanced chemical vapor deposition (PECVD) with reactant gases of SiH\({}_{4}\) (25 sccm) and NH\({}_{3}\) (25 sccm) at substrate temperature of 200 \({}^{\circ}\)C, under pressure of 0.65 torr, and radio frequency power of 90 watt. Reflectivity of samples ranging from the wavelength of 300 nm to 1200 nm was measured by Hitachi U-4100 (Hitachi, Tokyo, Japan).
# An Application of Instantaneous Spectral Entropy for the Condition Monitoring of Wind Turbines
## 6 Discussion  
The experimental results show that the Instantaneous (Shannon) Spectral Entropy can be effectively used as a time-dependent damage index for Pattern Recognition-based SHM. However, one must use care in obtaining a time-frequency distribution which is as refined as possible, especially along the frequency axis. For this reason, a dedicated study was carried out.  
High \(\gamma\) and \(\beta\) values return the highest possible time duration and number of oscillations under the GWT envelope, which in turn grants the highest frequency resolution achievable at any instant. This greatly increases the damage detection capabilities of the proposed entropy-based approach. The performance reaches a plateau at a certain point, where the instantaneous power spectrum is refined enough, and further increasing \(\Delta f\) does not significantly improve the final results. In this application, as mentioned previously, this was found at \(\beta\cong 20\), \(\gamma\cong 3\), which therefore constitute the lower boundaries of the range of suggested settings. If one is interested in further improving the detectability of damage (by further shrinking the confidence interval around the normality model), according to these findings, increasing both \(\beta\) and \(\gamma\) might be helpful. The optimal pair of (\(\gamma\), \(\beta\)) is, therefore, only limited by possible variations in the computational effort required. However, from the point of view of the computational effort, it was found that there is no relevant difference between different parameters.  
However, due to the well-known optimal trade-off between time and frequency resolution (recalled in Section 3.2), it is strongly suggested to test \(\gamma=3\) as a first attempt, independently from the specific dataset, before increasing \(\beta\). Only if, after reaching \(\beta=40\), the resolution \(\Delta f\) is still insufficient to obtain reliable \(\text{ISE}(t)\) estimates, the symmetry parameter should be further increased.
# Retractable Wireless Charging Windings for Inspection Robots
## 3 Design and Simulation of Retractable Wireless Power Transfer Coils
### Misalignment Sensitivity and Performance  
Misalignment is a critical factor that significantly influences the efficiency of WPT systems, especially in mobile or dynamically positioned applications. In this study, the performance of the proposed square coil design is evaluated under two primary misalignment scenarios: lateral displacement and angular deviation. These analyses are conducted using simulation tools prior to experimental validation to assess the robustness of the electromagnetic coupling under realistic operating conditions.  
Further study assesses the linear and angular misalignment based on the geometrical configurations of WPT coils with different edges, which are determined as \(N\). Figure 7 depicts the setup for both conditions. Figure 8a-c show the linear misalignment of the different WPT coil shapes. As the distance between the transmitter coil (Tx) and receiver coil (Rx) increases, \(k\) will also decrease, indicating the decrement of the coupling point between these two coils along the x-axis. Translation along the y- and z-axes shows a slight impact on \(k\) when Rx is positioned accordingly. Linear misalignment along the x-axis shows a significant reduction in \(k\) compared to the other two axes. The observation on angular misalignment presented in Figure 8d-f shows that the rotations along the x-axis have minimal impact on \(k\). The rotations along the alternative two axes significantly decrease the coupling coefficient, implying a decrease in system performance under angular misalignment conditions.  
These findings highlight the importance of alignment control in reconfigurable WPT systems. While the square geometry offers practical advantages for mechanical deployment, its sensitivity to misalignment presents a challenge for real-world use. This emphasizes the need for further design refinements, such as adaptive alignment mechanisms, flux-guiding materials, or alternative coil topologies with improved tolerance to spatial variations.
## 2 System Model
### Polarization Mode Dispersion  
The phase of transmitted signals are distorted owing to high capacity and long cover path. The transmitted signals are separated into multiple mode as arrived at the receiver side with a slightly different time as described in Figure 4. In results the phase is changed of the received signal and the pulse gets broader. At higher distance and speed, the impact of phase change and pulse broadening are increased further.  
Figure 3: IDSP receiver internal framework.  
Figure 2: Induction of unwanted frequencies due to FWM.  
Therefore, it is shown in Figure 4 that PMD is the key source of transmitted signal degradation and positive BER and FWM effect. To overcome the PMD issues a fruitful management technique is necessary for achieving acceptable range of BER.
## 2 Research Methods and Scenarios
### Fire Simulation Scenarios  
To distinguish the amount of smoke entering the stairwell based on the type of apartment, the installation type of the air curtain, and the differences in air-curtain wind speed, simulation scenarios were set as shown in Table 1. A scenario assuming a fire originating in the central part of the apartment living space was considered, and scenario variables were set based on the building type, the installation type of the air curtain, and the air-curtain wind speed. The wind speeds of the air curtains were selected based on the  
Figure 1: Study outline.  
speeds of products available in the market as 10 m/s, 18 m/s, and 35 m/s. Furthermore, the spray angle of the air curtain was set at 30 degrees. The area of the exhaust and supply vents for the horizontal air curtain was 0.25 m\({}^{2}\), while for the vertical air curtain, it was 0.5 m\({}^{2}\), achieved by connecting two horizontal units.  
Figure 2 shows the installation of air curtains. Figure 2a depicts the installation of a horizontal air curtain. It is installed at the top of the emergency stairwell fire door, horizontally aligned with the ceiling. Figure 2b depicts the installation of a vertical air curtain. It is installed perpendicular to the floor on the side opposite the hinges of the emergency stairwell fire door.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline \multicolumn{1}{c}{**Simulation Model**} & **Installation Type** & \multicolumn{1}{c}{\begin{tabular}{c} **Maximum Wind** \\ **Speed of Air Curtain** \\ \end{tabular} } \\ \hline \hline \multirow{7}{*}{Case 1} & Case 1-None & No air curtain installed & - \\ \cline{2-4}  & Case 1-H-10 & & 10 m/s \\ \cline{2-4}  & Case 1-H-18 & Horizontal air curtain & 18 m/s \\ \cline{2-4}  & Case 1-H-35 & & 35 m/s \\ \cline{2-4}  & Case 1-V-10 & & 10 m/s \\ \cline{2-4}  & Case 1-V-18 & Vertical air curtain & 18 m/s \\ \cline{2-4}  & Case 1-V-35 & & 35 m/s \\ \hline \multirow{7}{*}{Case 2} & Case 2-None & No air curtain installed & - \\ \cline{2-4}  & Case 2-H-10 & & 10 m/s \\ \cline{2-4}  & Case 2-H-18 & Horizontal air curtain & 18 m/s \\ \cline{2-4}  & Case 2-H-35 & & 35 m/s \\ \cline{2-4}  & Case 2-V-10 & & 10 m/s \\ \cline{2-4}  & Case 2-V-18 & Vertical air curtain & 18 m/s \\ \cline{2-4}  & Case 2-V-35 & & 35 m/s \\ \cline{2-4}  & Case 2-H-35-2 & \
\begin{tabular}{c} Horizontal air curtain \\ (with stairwell external wall open) \\ \end{tabular} & 35 m/s \\ \cline{2-4}  & Case 2-V-35-2 &
\begin{tabular}{c} Vertical air curtain \\ (with stairwell external wall open) \\ \end{tabular} & 35 m/s \\ \hline \multirow{7}{*}{Case 3} & Case 3-None & No air curtain installed & \\ \cline{2-4}  & Case 3-H-10 & & 10 m/s \\ \cline{2-4}  & Case 3-H-18 & Horizontal air curtain & 18 m/s \\ \cline{2-4}  & Case 3-H-35 & & 35 m/s \\ \cline{2-4}  & Case 3-V-10 & & 10 m/s \\ \cline{2-4}  & Case 3-V-18 & Vertical air curtain & 18 m/s \\ \cline{2-4}  & Case 3-V-35 & & 35 m/s \\ \hline \hline \end{tabular}
\end{table}
Table 1: Fire simulation scenarios.
# Machine Learning Failure-Aware Scheme for Profit Maximization in the Cloud Market
## 2 Related Work
The suggested scheme enables CPs to accurately estimate supply and demand in the cloud market. Furthermore, the method determines the best multi-server configuration to maximize the CP's profit. Authors propose new models for cloud service revenue and costs in [24]. The trading cloud resources problem was formulated as a profit optimization problem, and a heuristic method based on a grouped grey wolf optimizer (GWO) was proposed to extract the optimal multi-server setup for a given client demand. In [25], the authors analyzed a deadline constraint that may affect the profit of CPs. Furthermore, a new mathematical model was proposed to analyze the relationship between customer satisfaction and the revenues of CPs. It can be noticed from the previous discussion that in the cloud market there are different motivations for clients and the CP. These motivations for both sides should be evaluated and appropriately addressed so that a more thorough CRs trading algorithm can be developed, which might serve to offer both parties with sufficient incentives to stay and engage with the cloud, leading to a sustainable system. However, the majority of past research has come from either the incentive for clients or the CP to solve this issue. In contrast, this work attempts to investigate the CRs trading problem in cloud computing by addressing the key motives for both parties, namely, maximizing CP profit and meeting client expectations. When figuring out the CRs redundancy strategy in the cloud market, many state-of-the-art methods fail to consider the issue of the network's potentially enormous resource consumption. Moreover, traditional approaches could not adjust to the market shift toward CR failure in the cloud. With this in mind, we propose a novel adaptive fault-tolerantscheme, distinct from existing approaches, in which the optimal number of CRs to be used for replacing a failed CR is calculated at each system epoch. Scalability is achieved by grouping customers into manageable clusters and having a central CP oversee all trading activity for each group. For the trading of CRs, our scheme can be implemented with little to no additional infrastructure. In the event of CRs failure, the job can continue to run thanks to migration strategies proposed in the literature. Nonetheless, shoddy migrations lengthen the migration process, cause disruptions in service, and reduce application performance.