esa-sceva/satcom-chunk-collection huggingface dataset:
# A Hierarchical Sparse Discriminant Autoencoder for Bearing Fault Diagnosis
## 4 Experimental Verification
### Experimental Test 2  
In order to verify the diagnostic capabilities of the network model proposed in this paper, four sets of rolling bearing data with different speeds from the same private test platform in the author's laboratory are selected for verification testing. In this study, the signal with a sampling frequency of 25.6 kHz was selected as the test data. The test platform is shown in Figure 12.  
Similar to test one, the four types of fault data, including normal conditions under the conditions of rotation speed 900 rpm, 1100 rpm, 1300 rpm and 1500 rpm, are obtained, respectively. The length of each group of samples is 600, and the ratio of the testing set to the training set is the same as that of test one. The specific data set division is shown  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & **Data Sets** & **A** & **B** & **C** & **D** \\ \hline \multirow{3}{*}{LGSSAE} & Average accuracy & 90.23\% & 87.31\% & 87.86\% & 88.11\% \\  & Standard deviation & 0.047\% & 0.0452 & 0.0375 & 0.0382 \\  & Average accuracy & 95.51\% & 89.24\% & 88.94\% & 88.61\% \\  & Standard deviation & 0.0230 & 0.0501 & 0.0423 & 0.0328 \\  & Average accuracy & 96.12\% & 93.81\% & 94.73\% & 92.80\% \\  & Standard deviation & 0.0276 & 0.0246 & 0.0099 & 0.0340 \\  & Average accuracy & 83.25\% & 80.80\% & 79.93\% & 81.86\% \\  & Standard deviation & 0.0524 & 0.0518 & 0.0548 & 0.0523 \\  & Average accuracy & 99.39\% & 99.11\% & 99.11\% & 99.09\% \\  & Standard deviation & 0.0040 & 0.0036 & 0.0030 & 0.0031 \\ \hline \hline \end{tabular}
\end{table}
Table 3: The experimental results of different comparison methods in the CWRU data set.  
Figure 10: Comparison of experimental results of different methods in data set D.  
are the average of 20 trials to eliminate the randomness of the data. Among them, the optimal hierarchical sparse parameter is [0.0888, 0.1011, 0.1069, 0.1060, 0.0570, 0.0304], and the optimal non-hierarchical sparse parameter is [0.0561, 0.1009].  
Figure 13 shows the experimental results of the network using the hierarchical sparse strategy and the network not using the hierarchical sparse strategy in the data sets E, F, G and H. Based on the observation of Figure 13a, the KL divergence values of the first layer of neurons and the third layer of neurons are significantly reduced under the action of the hierarchical sparse strategy. Although on the four data sets of E, F, G and H, the sparsity of the second layer of neurons is not affected by the hierarchical sparsity strategy. However, Figure 13b shows that the hierarchical sparse strategy has obvious sparse optimization for the overall HSDAE network. In summary, the experimental results of four sets of data show that the hierarchical sparsity strategy can indeed reduce the correlation between the sparsity of neuron layers and the number of layers in the multi-layer network.
# Performance Analysis of Existing ITS Technologies: Evaluation and Coexistence
###### Abstract
The main contribution of this study is to propose a comprehensive analysis model that can evaluate ITS technologies according to different parameters, such as data rate, channel capacity and density. Furthermore, this evaluation model's outcomes depend on the particular requirement of a use case. As such, the following issues are identified:  
* The suitable configurations for each ITS technology according to a specific use case;
* The pros and cons of ITS technologies are identified (evaluated and compared) to determine their suitability for a use case requirement;  
Figure 1: Vehicular communications. * A density-sharing proposition for the coexistence between these ITS technologies;
* Suggest adaptive configuration mechanisms' interest in system performance, adapting the need to the user context through road profiles and environment variability (infrastructure, data, etc.). The rest of the paper is organized as follows. Section 2 describes both ITS technologies' PHY/MAC layers and illustrates an overview of the previous evaluation work. Section 3 evaluates theoretical channel occupancy and provides simulation results for performance evaluation and comparison. The new studies on spectrum-sharing methodologies between ITS Technologies are summarised in Section 4 with simulation results for the coexistence proposition. The challenge of the feasibility of adapting the network configuration to environment-changing situations is addressed in Section 5. Finally, Section 6 concludes the paper and suggests some future directions.
## 2 Materials and Methods
### Methodological Approach and Instrumentation
The desideratum is the creation of the Site Layout Plan, a comprehensive design that highlights the layout of the proposed construction inside the terrain, together with the coordinates and the stake-out elements of the building reference points (usually axes intersections). The stake-out elements consist of horizontal angles and distances from known geodetic points or control points, together with the instrumentation and layout method used in order to mark the position of the designed building. These horizontal angles and distances can be calculated from the Cartesian coordinates of the control/geodetical points and the designed points of the building, and can be done manually or by spreadsheet software. Total stations have the processing capabilities of instantly calculating these values, but it is recommended to also have them calculated and displayed on the final site layout plan. In terms of used instrumentation, the total station and GNSS systems are the most used by the survey engineer. GNSS systems are the perfect choice for topographical surveys where the field conditions are optimal (sufficient satellite availability, network RTK services, open field etc.). In recent decades, GNSS systems have been used to obtain geodetic networks or control points, for precise measurements, accurate monitoring processes or construction stake-outs. In the case of classical methods of determining new geodetic points, by means of resection or traverse networks, a current deficiency is the lack of reliable control points or geodetic points, almost completely destroyed in the past decades. The total station is often considered the right hand of the survey engineer, and offers pinpoint accuracy and can yield precise observations, as well as efficient and reliable layout of reference points. The instruments used in this case study were: Leica Viva GS08 Global Navigation Satellite System used in real-time kinematics (RTK) mode for obtaining the control points (St1 and St2) with a horizontal precision between 0.014 m and 0.020 m ensured by online RTK corrections provided by the Romanian Position Determination System (ROMPOS) and the connection to a national permanent GNSS reference station; the total station used was a Leica TS02 plus, which has a very good measurement accuracy of angles of 3\({}^{\prime\prime}\) and distances of \(\pm\)2 mm + 2 ppm.
# Comparison of NeQuick G and Klobuchar Model Performances at Single-Frequency User Level +
###### Abstract  
In this study, the NeQuick G and Klobuchar models are evaluated by monitoring performance issues related to ionosphere activity for single-frequency users. The effects of radio frequency (RF) signal propagation through the ionosphere may have a significant impact on satellite communication and navigation systems because of geomagnetic field geometry near the magnetic equator and in the proximity to the high- and low-latitude zones. An ongoing challenge is determining how accurate the ionospheric models employed by existing Global Navigation Satellite Systems (GNSSs) are. This work investigates the patterns of total electron content (TEC) fluctuations over distinct zones from 1 January 2019 to 30 June 2022. Measurements are collected at station networks deployed worldwide. Firstly, monthly and seasonal variations of TECs are analysed. Secondly, the TEC 'availability' parameter, as the percentage of time when the TEC error is compliant with the specification of the Galileo Single-Frequency Ionosphere Algorithm (\"NeQuick G' model), is introduced. The TEC error defines the difference between (a) the model TEC, obtained by either the NeQuick G or the Klobuchar model over a given station, and (b) the reference TEC, based on observations from networks of GNSS receivers. Finally, the position, velocity, and time (PVT), along with broadcast group delays (BGDs) are analysed and the PVT accuracy is compared between the NeQuick G and Klobuchar models. In 3.5 years, the seasonal behaviour of TEC shows maxima during the March and October equinox and minima during the June and December solstice. Moreover, an increase in the TEC values and the amount of TEC errors are visible as we are approaching the next solar maximum. Preliminary results show a larger associated positioning error using the Klobuchar than the NeQuick G model. However, the difference is zone-dependent, most evident in equatorial regions. This collaborative study of the GRC, NMA, TUW, and SRC was performed under the Framework Partnership Agreements (GSA/GRANT/04/2016).  
NeQuick G; Klobuchar; position accuracy +
Footnote †: This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license ([[https://creativecommons.org/licenses/py/4.0/](https://creativecommons.org/licenses/py/4.0/)]([https://creativecommons.org/licenses/py/4.0/](https://creativecommons.org/licenses/py/4.0/))).
## 1 Introduction
### Day-ahead GHI Forecasting  
For day-ahead GHI forecasting, both numerical weather prediction (NWP) [15] and satellite imagery provide effective tools for forecasting irradiance. The National Center for Environmental Prediction (NCEP), a part of NOAA, runs two versions of the Rapid Refresh (RAP) numerical weather model to predict environmental data. The first version generates weather data on a 13-km (8-mile) resolution horizontal grid and the second, the High-Resolution Rapid Refresh (HRRR), generates data on a 3-km (2-mile) grid. RAP forecasts use multiple data sources: commercial aircraft weather data,balloon data, radar data, surface observations, and satellite data to generate forecasts with hourly resolution in time and forecast lengths of 18 hours. For further details, consult the RAP website [16]. RAP data are available for download through the National Model Archive and Distribution System (NOMADS). Several benefits accrue from using NWP for irradiance forecasting: NOAA incurs much of the computational burden and these models incorporate first-principles physics such as the Navier-Stokes equations, thereby allowing for the dynamic formation of clouds. Satellite technology is advancing rapidly with GOES-16 (Geostationary Operational Environmental Satellite) pictures being updated every 5 min with maximum resolution of 5000 by 3000 pixels. Figure 1 shows such an image cropped to the central Texas region. The temporal sampling of the data is still insufficient to support optical flow predictions 15-min ahead. Continued improvements in GOES-R (geostationary satellite with high spatial and temporal resolution) may well make the satellite approach to minutes-ahead irradiance prediction more attractive in the future [17; 18; 19; 20]. Statistical methods based on historical time-series data and climatology are also useful for day-ahead PV forecasting.
## 5 Results
### Mediating Effects Analysis  
#### 5.2.1 Empirical Test of the Mediating Effect of Urban Green Innovation  
The regression results on the mediating effect of urban green innovation are reported in Table 3. Column (1) indicates a significant negative impact of GPP on urban carbon emissions intensity, and the coefficient suggests that a 1% increase in GPP expenditures is associated with a 1.548% reduction in the latter. In Column (3), the inclusion of urban green innovation lowers the coefficient for GPP to \(-1.400\), which remains statistically significant at the 1% level. This suggests that even with the mediation of urban green innovation, GPP continues to exert a notable negative effect on urban carbon emissions intensity. These results support the demand-side pull hypothesis in the circular economy theory [57], thereby indicating that governmental initiatives through GPP can stimulate markets for sustainable products and enhance market-driven strategies for urban carbon emissions intensity reduction.  
Regarding the mediating effect mechanism, regression results from Column (2) indicate that GPP significantly promotes urban green innovation, thus fulfilling the first-stage mediation conditions. This indicates that GPP drives market participants' innovation through demand-pull effects, which arise from four channels: policy-driven demand, standards pressure, policy signals, and knowledge spillover networks [33; 58; 59]. Furthermore, regression results from Column (3) indicate that urban green innovation significantly reduces urban carbon emissions intensity, which validates the chain transmission logic and confirms second-stage mediation criteria. The mediating effect accounted for 9.65%2 of the total effect, thereby establishing a partial mediation. Additionally, both Sobel test and Bootstrap method (with 5000 resampling iterations) confirm significance at the 1% level, ultimately reinforcing the robustness of this mediating pathway and supporting H2.
## 3 General Properties of Hyaluronic Acid-Catechol  
### Biocompatibility  
High levels of HA are present in tissues and cartilage, particularly in those of the musculoskeletal system. In addition, HA is widely used in medical applications mainly due to its biocompatibility. The conjugation of molecules to HA does not significantly affect its biocompatibility. For instance, injectable tyramine-conjugated HA hydrogels prepared by the oxidative crosslinking of phenolic groups maintain high cell viability (>95%) of human mesenchymal stem cells (hMSCs) for up to 14 days [87]. In addition, the viability of MSCs in an HA hydrogel crosslinked with polyethylene glycol (HA-PEG gel) was \(-100\%\) when \(10^{6}\) cells mL\({}^{-1}\) of MSCs were treated with the hydrogel for three days [88].  
Similarly, HA-catechol is also non-cytotoxic and biocompatible. Treatment of cells at a density of \(1.0\times 10^{6}\) cells/\(100\)\(\mu\)L with a pre-gelation HA-catechol solution preserves cell viability (\(-100\%\)) [46]. Treatment with extracts of HA-catechol hydrogels maintains \(\sim\)83% viability in L92 cells compared to that obtained using fresh media. In addition, the viability of human hepatocytes (hHEPs) encapsulated in HA-catechol hydrogels prepared by the addition of NaIO\({}_{4}\) was \(\sim\)70.9%, which is far higher than that observed using HA-methacrylate hydrogels (\(\sim\)52.2%) on day 14 of treatment [46; 89]. Furthermore, HA-catechol hydrogels incorporated with basic fibroblast growth factor exhibit improved hHEPs cell viability to \(\sim\)81.4% after 14 days [37]. The viability of human neural stem cells (hMSCs) in an HA-catechol hydrogel after seven days was approximately 70%, which is two-fold that observed using an HA-methacrylate hydrogel (less than 30%).
## 2 Laser-Driven Very-High-Energy Electron/Photon Beam Radiation Therapy System
### Drive Laser System  
The drive laser system for producing multi-TW laser pulses is based on the chirp pulse amplification technique [29], as shown in Figure 3. In this drive laser system, a low-energy laser pulse is produced by a front end, including a femtosecond oscillator and pulse stretcher wherein an oscillator pulse is stretched out in time, by means of a pair of diffraction gratings, having the effect of offsetting in time the various spectral components of the original low-energy pulse. The stretched pulse then has a lower peak power and a longer duration than the original pulse. An output pulse from the front end then seeds an amplifier chain. The pulse passing through this amplifier chain is amplified so as to generate a high-energy pulse. This amplified pulse is compressed timewise by an optical pulse compressor installed in a compressor vacuum chamber. The pulse compressor chamber is maintained at a pressure of the order of \(10^{-4}\) Pa. The optical pulse compressor comprises a pair of diffraction gratings, grouping together in time the various spectral components of the pulse. The output pulse emerging from this optical compressor then has a very high energy and very short duration so that its energy and duration are optimized for producing an electron beam. A whole laser system, a vacuum pump, and the gantry drive system are installed in the cover case, as shown in Figure 2.  
For many practical applications of laser plasma accelerators, it is essential to employ high average power, high-efficiency drive lasers operated at the high repetition pulse rate. In particular, the stability and positioning precision of electron beams are critical issues for the medical accelerator performance [2]. For laser plasma accelerators, these issues are largely determined by the stability of the laser  
Figure 3: A schematic diagram of the drive laser system using the chirp pulse amplification technique.  
performance, which is significantly improved as the pulse repetition rate increases. One such high average power laser system is the Coherent Amplifying Network (CAN) laser [30]. Here the conventional rod or slab laser amplifiers are replaced by a network of optical-fiber-based amplifiers. A femtosecond seed-laser pulse is repeatedly split and amplified through this network. The resulting pulses are then recombined coherently with precise individual phase control to produce a single amplified global laser pulse with a 1 J level of energy at the high repetition rate of 1 kHz to 1 MHz with efficiency of 30%-40%.
# Frequency-Bounded Matching Strategy for Wideband LNA Design Utilising a Relaxed SSNM Approach
## 4 Wideband LNA Design Strategy Using Modified SSNM Conditions
### ISMN2: OM2 \(\approx\) IM3  
To synthesise the second inter-stage matching network (ISMN2), again, it is necessary to enforce the relaxed matching condition. The input port of ISMN2, looking into the matching network, is matched at the three frequency points to the reference load reflection coefficients derived from the output of the second stage. Similarly, the output side of ISMN2 is simultaneously matched at these frequencies to the reference source reflection coefficients specified at the input of the third stage. Figure 9 depicts the matching conditions for the ISMN2.  
Complementing these visualisations (Figures 8 and 9), Table 2 summarises the corresponding IM and OM values obtained at these frequencies.  
Figure 8: Smith chart representation of various reflection coefficients for ISMN1.  
Figure 9: Smith chart representation of reflection coefficients for ISMN2.  
The corresponding S-parameters of the designed MMIC using lossless components are shown in Figure 10.  
These combined charts and numerical values confirm that the proposed relaxed SSNM framework effectively guides the wideband MMIC design by providing practical, frequency-dependent reflection coefficient targets that maintain stable and efficient operation throughout the desired frequency range.  
This entire strategy to design a wideband matching network is summarised in the flow chart shown in Figure 11:  
\begin{table}
\begin{tabular}{c c c c c c c} \hline  & **IM (\(f_{1}\))** & **IM (\(f_{2}\))** & **IM (\(f_{3}\))** & **OM (\(f_{1}\))** & **OM (\(f_{2}\))** & **OM (\(f_{3}\))** \\ \hline Stage1 & 0.10 & 0.067 & 0.072 & 0.270 & 0.401 & 0.442 \\ \hline Stage2 & 0.253 & 0.384 & 0.42 & 0.052 & 0.038 & 0.038 \\ \hline Stage3 & 0.070 & 0.051 & 0.047 & 0.148 & 0.091 & 0.123 \\ \hline \end{tabular}
\end{table}
Table 2: IM-OM values at three frequencies for three stages.  
Figure 10: S-parameter vs. frequency of 3-stage LNA with lossless transmission lines.
## 3 Methodology and Algorithm Descriptions
### Parameter Settings  
To evaluate performance under varying rule mining intensities, several parameters were systematically adjusted during testing. Minimum support levels were set at 0.10, 0.15, and 0.20, while minimum confidence thresholds ranged from 0.10 to 1.00 in increments of 0.05. Additionally, lift was employed as a supplementary filtering metric to emphasize statistically significant association rules.  
The selected support thresholds of 0.10, 0.15, and 0.20 were chosen to simulate realistic e-commerce scenarios involving different levels of item popularity and purchase frequency. A minimum support of 0.10 reflects associations involving niche or long-tail products--items that appear less frequently in the overall transaction set but can reveal valuable cross-well opportunities or highly targeted recommendations. In contrast, a threshold of 0.20 captures more mainstream or high-frequency items, such as bestsellers or seasonally popular products, which are relevant to broader customer segments. The intermediate value of 0.15 represents a balanced scenario in which both moderately popular and occasional items can contribute to rule generation. This gradation enables the evaluation of algorithm behavior across different density levels of frequent itemsets.  
Furthermore, the decision to vary the confidence threshold in 0.05 increments (from 0.10 to 1.00) provides a granular view of rule quality variation. In real-world practice, data scientists often need to fine-tune confidence thresholds to balance rule strength and coverage--a small change in this parameter can substantially alter the number and relevance of discovered rules. The 0.05 increment strikes a practical balance between precision in parameter tuning and computational feasibility, allowing for statistically meaningful comparisons without producing redundant or overly similar results.