esa-sceva/satcom-chunk-collection huggingface dataset:
## 3 Results
### Land Use Evolution
#### 3.1.2 Spatial Evolution of Land Use over 40 Years  
Transformation matrices, trend state index, and annual average net change rate were calculated to further analyze the degree of land use evolution (Tables 4 and 5). The transformation matrices revealed several noteworthy patterns during the study period. The conversion dynamics remained relatively stable during 1980-2000, followed by significant changes during 2010-2020 with increased transformation intensity. An asymmetric conversion relationship was observed between cropland and forests, while construction land showed a distinct one-way transformation pattern. Notably, two critical transitions emerged: a sharp increase in grassland-to-unused land conversion during 2010-2020 after three decades of stability, and the diversification of construction land sources from predominantly cropland to multiple land classes. Although the water area maintained overall stability, it exhibited persistent minor transformations throughout the study period. Figure 2: Evolution of land use area in China (1980–2020). Between 1980 and 1990, the greatest net increase was seen in cropland, followed by construction and unused land. Construction land exhibited the highest trend index (0.07) and net change rate (0.62%), indicating a rapid expansion over the past 10 years. Between 1990 and 2000, forests and grassland declined, while cropland and construction land expanded most notably (0.16% and 0.90%, respectively). Between 2000 and 2010, construction
# Computed Tomography-Driven Design and Fused Filament Fabrication of Graded Density Bone Scaffolds
###### Abstract  
The design of scaffolds and prostheses benefits from the opportunities provided by additive manufacturing technologies. Specifically, scaffold design using cellular structures based on lattices has become a significant focus. These lattice-based scaffolds exhibit intricate and complex shapes with controlled macro-porosity. In this study, a method is presented that enables the modeling of a graded-density lattice structure for material extrusion additive manufacturing, without relying on a geometric lattice model. The methodology utilizes computed tomography (CT) scans as inputs to obtaining a 3D scalar field and a surface model. The lattice structure is designed and generated within the computer-aided manufacturing (CAM) software, ensuring consistent machine toolpaths. The 3D scalar field, representing a relative density map derived from CT Hounsfield units, drives the variation of the extrusion parameters generated by the CAM, achieving a graded-density lattice. To demonstrate the effectiveness of the method, a section of a human femur bone with a lattice with a triply periodic minimal surface (TPMS) Syroid pattern was designed and 3D-printed, replicating the relative density of the target tissue.  
Keywords:volumetric modeling; graded lattices; functionally graded lattice structures; computed tomography; fused filament fabrication; additive manufacturing +
Footnote †: journal: Applied Sciences
## 7 Antenna Qualification and Acceptance Test
### Thermovacuum Test (TVAC)  
The primary objective of the TVAC is to elevate the temperature of the QM S Band antenna beyond the levels attained in the thermal analysis, thereby demonstrating the subsystem's capacity to function effectively in pertinent thermal-vacuum circumstances and to withstand thermal cycles in such conditions without compromising its operational capabilities. For the purposes of this test, the antenna is to be mounted on the mass dummy and undergo eight cycles in two operating modes (hot and cold) so that the unit reaches temperature levels according to the specification limits (Table 4).  
TVAC tests are carried out in the Test Laboratory at INTA (TVC-2 thermal chamber COSMOS 02), and the equipment for testing is located in a cleanroom class ISO 8 (see Figure 21c).
# Estimating Road Segments Using Natural Point Correspondences of GPS Trajectories
## 4 Experiments  
For the experiments, we used the data set from the \"averaging GPS segments\" challenge ([[http://cs.uef.fi/sipu/segments/](http://cs.uef.fi/sipu/segments/)]([http://cs.uef.fi/sipu/segments/](http://cs.uef.fi/sipu/segments/))). This data set consists of samples from several open data sets (Joensuu, Chicago, Berlin, Athens) [6] collected in different countries. Examples from the data set are visualized  
Figure 1: Visualization of the intermediate steps of the algorithm.  
in the figures at the pages 8 and following. Each sample contained a set of trajectories mapped to a ground truth road segment which was extracted from OpenStreetMap. The coordinates of the points in the trajectories were normalized into the range from 0 to 1 and projected into a local Euclidean coordinate system. The quality of the predicted road segment was measured using the HC-SIM metric [6]. This metric, as an extension of the C-SIM [11] metric, uses a desensitization approach to determine the overlap of two rasterized and dilated lines, in this case, the predicted line and the reference line. The hierarchical part applies C-SIM with different grid resolutions and averages the determined similarity measure. In this work, we reported two sets of experiments. In the first experiment, we performed an ablation study which starts with the most simple version of the proposed algorithm and adds additional steps of the algorithm to determine the influence of each step on the performance of the algorithm. The second set of experiments was used to evaluate the influence of the \(\epsilon\) parameter from the Douglas-Peuker algorithm. This value was varied in the range from 0.0 (no approximation) to 0.4. Since the coordinates are normalized, this value range is applicable to all samples regardless of the length of the segment in reality. In this experiment, we used the version of the algorithm without the alignment step as it turned out not to improve the results.  
Both experiments were evaluated using the average HC-SIM measure over all 100 samples and by visually analyzing several results. Since the algorithm is deterministic, it was not necessary to evaluate the experiments multiple times.
## 4 Experiments
### Analysis of Experimental Data of Bearing Failure Simulation on Bearing Life Prediction Test Bench
#### 4.2.1 LY-GZ-02 Experimental Bench Data Description  
The LZ-GZ-02 bearing experimental bench model was selected to simulate faulty bearing working conditions under normal working conditions. Vibration acceleration sensors and data acquisition devices were used to collect the vibration data under each faulty condition of the bearing. Figure 7 illustrates the relevant parts of the experimental setup, which mainly consisted of hydraulic cylinders, an operating table, a data collector, and other devices.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Method** & **A-B** & **A-C** & **B-A** & **B-C** & **C-A** & **C-B** & **Average Accuracy** \\ \hline SDAE + JGSA [30] & 93.4\% & 90.1\% & 90\% & 93.8\% & 91.2\% & 94.7\% & 92.2\% \\ DDC [31] & 98.4\% & 95.7\% & 97.7\% & 98.3\% & 88.5\% & 96.7\% & 95.9\% \\ DACNN [32] & 97.3\% & 98.3\% & 96.2\% & 98.1\% & 98.1\% & 98.4\% & 97.7\% \\ Proposed method & 99.1\% & 99.4\% & 99.6\% & 98.6\% & 99.1\% & 99\% & 99.3\% \\ \hline \hline \end{tabular}
\end{table}
Table 6: Testing results of different methods.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Structure** & **Epoch** & **Accuracy** \\ \hline One FC layers + dropout + output & 1000 & 83.5\% \\ Two FC layers + dropout + output & 1000 & 99.4\% \\ Three FC layers + dropout + output & 1000 & 93.2\% \\ \hline \hline \end{tabular}
\end{table}
Table 5: Experimental results for different FC layer counts under the A-C migration task.  
Bearings in four different states of health were each operated under three different load conditions at the same rotational speed. The bearing health states included normal (N), outer ring failure (OF), inner ring failure (IF), and rolling element failure (RF). As shown in Table 7, the loads were 0 N, 1000 N, and 2000 N. The sampling frequency of the experimental acquisition device was 20 KHz. For each type of load, the samples for each bearing state were 1000, and the sample length was 1024. Time-frequency images of the vibration acceleration signals of the bearings at 1000 rpm, with loads of 1000 N under the four states, are shown in Figure 8.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Condition** & **Fault Type** & **Label** & **Sample Size** & **Load** \\ \hline \multirow{4}{*}{A} & RF & 0 & 1000 & \\  & IF & 1 & 1000 & \\  & N & 2 & 1000 & 0 N \\  & OF & 3 & 1000 & \\ \hline \multirow{4}{*}{B} & RF & 0 & 1000 & \\  & IF & 1 & 1000 & \\ \cline{1-1}  & N & 2 & 1000 & 1000 N \\ \cline{1-1}  & OF & 3 & 1000 & \\ \hline \multirow{4}{*}{C} & RF & 0 & 1000 & \\  & IF & 1 & 1000 & 2000 N \\ \cline{1-1}  & N & 2 & 1000 & \\ \cline{1-1}  & OF & 3 & 1000 & \\ \hline \hline \end{tabular}
\end{table}
Table 7: Descriptions of the datasets.  
Figure 7: LY-GZ-02 laboratory bench.
# Modification of Nonlinear Controller for Asymmetric Marine Vehicles Moving in Horizontal Plane
## 4 Numerical Simulations
### Vehicles and Test Conditions
#### 4.1.3 Comparison with Algorithm Based on Velocity Transformations
During this time, there is a large increase in the kinetic energy (Figure 8c) and also in the force and torque (Figure 8d). **Sine-cosine trajectory**. For this desired trajectory, the set of parameters was slightly changed to improve the control performance. It was as follows:  
\[\text{Kambara }\ k_{1}=k_{2}=0.30,\ \ k_{3}=10;\ \ k_{4}=1,\ \ k_{5}=5. \tag{49}\]  
The algorithm worked correctly, and for this trajectory only index values were given. The performance indexes for the VT control algorithm are presented in Table 6.  
A comparison of the proposed QV controller with the VT controller can be made based on the results shown in Tables 4 and 6. As can be seen from the data, in the tables, the VT controller had larger mean values mean(\(\sum\Delta p_{xy}\)) and standard deviation (except for the mean error for the SC trajectory) for the tracking error. Even if corrected, the results for the VT controller (assuming a different set of parameters) would be comparable, but there could \begin{table}
\begin{tabular}{c c c} \hline \hline  & **Kambara** & \\ \hline  & **L** & **SC** \\ \hline mean(\(\sum\Delta p_{xy}\)) & 0.5750 & 0.2750 \\ std(\(\sum\Delta p_{xy}\)) & 0.9292 & 0.3243 \\ RMS(\(||e||\)) & 0.8065 & 0.3726 \\ MIAC(\(\tau_{u}\)) & 75.174 & 68.921 \\ MIAC(\(\tau_{r}\)) & 3.7864 & 3.9702 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Performance indexes for VT controller (L-linear, SC-sine-cosine). Figure 8: Numerical test for Kambara, VT controller and linear trajectory: (**a**) desired and realized trajectory; (**b**) position errors; (**c**) kinetic energy time history; (**d**) applied force and torque. be undesirable oscillations. Therefore, it can be concluded that, for the assumed operating conditions, the proposed control algorithm is more efficient than the VT algorithm. The advantage of the QV controller is also evidenced by the fact that the values of the input signals are much smaller than those of the VT controller.
# Accurate Landmark Localization for Medical Images Using Perturbations
## 3 Materials and Methods
### Perturbation Operations
#### 3.3.4 Edge Detection  
Edge detection is performed using Canny edge detection algorithm [38], resulting in pixels with 0 (non-edge) or 1 (edge). The sigma value for the Canny edge detector is determined by random sampling from N(\(\mu\), \(\sigma^{2}\)), where \(\mu\) = 3.5, \(\sigma\) = 1.5. A larger value of sigma results in coarser scale edges and greater noise suppression effect.  
Unlike other operations that only degrade the information in the image, the edges have two opposite facets, degrading or upgrading the information. The image is upgraded in the sense that the positions that change the most in the image are highlighted by being converted to value 1, indicating the edge. As a result, it is expected that the landmarks lying close to the edges will be more easily detected. In contrast, the shading information disappears by edge detection. Therefore, the landmarks far from the edges should rely on global information. We expect that the two opposite effects will make the network more robust to image variations.
# Biomechanical Optimization of Lumbar Fusion Cages with a Porous Design: A Finite Element Analysis
###### Abstract  
LUMbar interbody fusion (LIF) is a standard treatment for spinal instability, yet postoperative subsidence and adjacent segment degeneration (ASD) remain critical challenges. This study evaluates the biomechanical efficacy of personalized porous fusion cages--featuring Gyroid (G-Cage) and Voronoi (V-Cage) architectures--against classic (C-Cage) and personalized (P-Cage) designs, aiming to enhance stability and mitigate subsidence risks. A finite element model of the L3-L4 segment, derived from CT scans of a healthy male volunteer, was developed to simulate six motion modes (compression, rotation, flexion, extension, and left/right bending). Biomechanical parameters, including range of motion (ROM), cage stress, endplate stress, and displacement, were analyzed. The results demonstrated that the V-Cage exhibited superior performance, reducing ROM by 51% in extension, cage stress by 41.7% in compression, and endplate stress by 63.7% in right bending compared to the C-Cage. The porous designs (G-Cage, V-Cage) exhibited biomimetic stress distribution and minimized micromotion, which was attributed to their trabecular-like architectures. These findings highlight the Voronoi-based porous cage as a biomechanically optimized solution, offering enhanced stability and reduced subsidence risk when compared to classic implants. The study underscores the potential of patient-specific porous designs in advancing LIF outcomes, warranting further clinical validation to translate computational insights into practical applications.  
Keywords:lumbar interbody fusion; finite element analysis; Voronoi porous structure; subsidence risk; adjacent segment degeneration +
Footnote †: journal: Applied sciences
## 3 Related Works  
In 1966, the Fourier transform (FT) was presented to the banks of sinusoidal frequency based on its orthogonality. To reduce the ISI effect, the cyclic-prefix (CP) was suggested in 1969 as an enhancement to OFDM systems. Researchers began to use OFDM for practical wireless communication in 1980. The FT is depicted in Equation (1).  
\[X(\omega)=\sum_{i=-\infty}^{\infty}x[n]e^{-i\omega n} \tag{1}\]  
Due to transmitting data by light source, the non-negative signal is a requirement in OWC signals. Then, before proceeding to the IDFT block, the waveform must be pre-processed. Asymmetrically clipped optical-OFDM (ACO-OFDM) and DC-biased optical-OFDM (DCO-OFDM) are currently two developed Li-Fi systems. On the other hand, the wavelet transform has several advantages over the Fourier transform, including no cyclic-prefix (CP) redundancy, reduced sub-channel interference, and greater spectral separation. The IEEE Standard Association recently defined wavelet OFDM (wavelet transform is the primary topic of IEEE 1901 for the power line communication (PLC)). It demonstrated that wavelet OFDM outperforms traditional OFDM. Ref. [10] proposes that wavelet OFDM is better than DCO-OFDM in terms of spectrum efficiency, side-lobe suppression, and bit error rate, and [11] proposes wavelet package approaches to OWC systems and shows that wavelet OFDM's PAPR (peak to average power ratio) is smaller and more robust in the face of channel imperfection. However, wavelet OFDM is difficult to deploy with high cost, so OFDM based on Fourier transform widely applied to the communication systems.
## 2 Materials and Methods
### MODIS Time Series  
The 2001-2013 time series of standard MODIS 16-day MOD13Q1 product (Collection 5) at 250 m resolution was used in the study. For each scene NDVI, band 2 (NIR: 0.840-0.876 \(\upmu\)m), band 7(MIR: 2.105-2.155 \(\upmu\)m) and QA (Quality Assessment denoting overall pixel reliability) information were extracted. NDII7 datasets were next computed following the formula:  
\[\text{NDII7}=(\text{NIR}-\text{MIR})/(\text{NIR}+\text{MIR}) \tag{1}\]  
Application of both indices was motivated by a desire to independently inspect drought impact on forest canopy photosynthesis activity, and foliage water content. All NDVI and NDII7 images were subsequently evaluated against QA. Pixels with the QA-usefulness values below acceptable [61] as well as outliers (confidence level 0.95 according to Chebyshev's Theorem) were linearly interpolated in the time domain. The process was performed in the TimeStats Software Tool [62] and addressed time-gaps not longer than a single observation. This condition allowed to substitute missing or corrupted observations, but at the same time limited amount of factitious values. As a result, 385 out of 52,394 pixels within the forest mask (Section 2.4) had incomplete 2001-2013 NDII7 time series and were excluded from further analyses. Spatial coverage of NDVI time series was not affected (information on number of forest pixels that underwent interpolation for NDVI and NDII7 time series is presented in Tables S1 and S2, respectively). Data preprocessing of both time series was concluded with the sensor degradation adjustment [63].
## Materials and Methods  
The schematic of the sample is shown in Figure 1a. The dielectric multilayer (made of alternating SiO\({}_{2}\) and Si\({}_{3}\)N\({}_{4}\) layers) was fabricated using plasma-enhanced chemical vapour deposition. The thicknesses of SiO\({}_{2}\) and Si\({}_{3}\)N\({}_{4}\) were 105 and 88 nm, respectively. The thickness of the top SiO\({}_{2}\) layer is defined as t nm, which will be varied in the following experiments and simulations. An Ag NW with a diameter of approximately 70 nm was deposited on this multilayer (Figure 1b). The Ag NW was purchased from XFNANO Materials Tech Co., Ltd., Nanjing, China. A laser beam (from a SuperK supercontinuum source, NKT Photonics, Birkered, Denmark) was used for excitation; it was first lens-coupled into a standard single-mode silica fibre, and its taper would be brought into contact with the Ag NW by a micromanipulator. As a result, the laser beam can be coupled into the Ag NW. The beam propagating along this NW was characterized by a home-built instrument for leakage radiation microscopy (LRM). A schematic of the experimental setup (LRM) is shown in Figure 1c. This LRM can collect both the front focal plane (FFP) and the back focal plane (BFP) images, which can be used to derive the propagation constants (\(\beta\) + i*\(\beta\)') of the SPP propagating along the Ag NW. \(\beta\)/K\({}_{0}\) is the effective refractive index of the plasmonic mode, and the imaginary part (\(\beta\)') represents the propagation loss. Details of image formation on the FFP and BFP, and how to derive the embedded optical information from the BFP and FFP images, can be found in references [29; 30; 31; 32; 33].
## 4 Results and Discussion
### Sharp Cornering and Successive Left-Right Turns Scenario  
The sharp cornering and successive right-left turn scenario appears to be one of the most challenging for the INS on the CAE metric (see Figures 5-7 and Figure 12). This scenario investigation involves analysis on 40 test sequences over a maximum travel distance of approximately 109 m. Reporting on the results presented in Table 13, it can be observed that the INS has a maximum CRSE and CAE displacement of 92.06 m compared to 12.71 m and 8.49 m, respectively, of the NN. On the orientation rate, the NN performs significantly better than the INS with a maximum CRSE and CAE of 0.41 rad/s and 0.13 rad/s against the INS's performance of 4.29 rad/s and 3.47 rad/s. These results further highlight the capability of the NN to significantly improve vehicular localisation during GPS outages with its reliability assured by its relatively low standard division. An example trajectory of the vehicle during the sharp cornering and successive left and right turn is shown in Figure 13.  
Figure 11: Showing the evolution of the estimation error over time in the hard brake scenario based on the (**a**) Displacement CRSE, (**b**) Displacement CAE, (**c**) Orientation rate CRSE and (**d**) Orientation rate CAE.  
Figure 12: Showing the evolution of the estimation error over time in the hard brake scenario based on the (**a**) Displacement CRSE, (**b**) Displacement CAE, (**c**) Orientation rate CRSE and (**d**) Orientation rate CAE.  
Figure 13: Trajectory of V-Vw8 sharp cornering and successive left and right turns data subset of the IO-VNBD.
# A Usable Encryption Solution for File-Based Geospatial Data within a Database File System
## 6 Discussion
### GIS Security Model and Security Analysis
#### 6.1.2 Confidentiality
The protection provided by the solution to each circumstance is substantiated as follows. Upon removing the disk from the DBFS server when files are in encrypted form or decrypted for legitimate users, the adversary will only have access to the encrypted spatial files stored within the database datafiles. Since the spatial files are decrypted into temporary LOBs, the LOBs containing the original spatial files are never replaced. This feature enables backups to always contain spatial files in encrypted form, and an adversary accessing the backup media will only find encrypted files in all cases. It leaves the adversary with one option--to break the security of the encryption. If an attacker manages to obtain the encrypted data and decryption algorithm, the adversary will still not be able to access the encryption keys stored in a database, as they are stored encrypted (using another key) inside the Oracle Wallet. Finally, if an adversary chooses to break the encryption security within the solution, the security of the AES algorithm will prevent information recovery. (3) _DBFS Maintainer:_ Finally, an adversary in the form of the DBFS maintainer, who is assigned to perform data backups, transfer them to another place, or destroy them, will always have access to encrypted data only. Since these LOBs are not permanent, they are normally not part of the backup plan and will not be backed up together with the database data while performing online database backups (hot backups). To prevent the maintainer from accessing the table containing the single-user and multi-user cryptographic keys, the SELECT access to the table containing the keys can be revoked, which will also prevent the keys from the table from being backed up with the encrypted spatial file. On the other hand, if the database datafiles are backed up after database shutdown (cold backup), the data warehouse maintainer will again only have access to encrypted datafiles [84]. This is because as soon as the database is closed, all transactions on the LOB are committed, and the decrypted spatial files are encrypted back. The spatial files that were decrypted within temporary LOBs in a temporary tablespace are _freed_ as soon as the database is shut down. To decrypt the obtained encrypted files stored in the database backup, the warehouse maintainer needs access to the decryption keys safeguarded using TDE and the Oracle Wallet. To access these keys, he/she needs SELECT privilege access to the database tables containing the keys, which are revoked from his default role privilege. Finally, the DBFS maintainer would be faced with needing to break the security of the encryption, which, as previously mentioned, is a very difficult task.