esa-sceva/satcom-chunk-collection huggingface dataset:
## 2 Legal Status of Mega-Constellations under International Space Law
### International Telecommunications Union in Regulating Mega-Constellations
#### 2.2.1 Frequency and Orbital Slot Allocation
The World Radio Communications Conferences demonstrate that Article 44.2 of the ITU Constitution [20] introduced the idea of equity and equitable access with regard to the use or sharing of radio frequencies and orbital positions. However, it has only been used in conjunction with a small number of allotment plans. These include, among other aspects, the provision and related frequency allotment plan for the aviation mobile service in the bands allotted solely to that service, the frequency allotted plan for the aviation mobile service, and related information [28]. Because of the rarity of such plans, new challenges arise in accessing appropriate radio frequencies due to increasing privatization, competition, globalization, and the abuse of ITU regulatory processes. Communication is substantial in operating a constellation because of the frequent need to communicate with the ground team and because satellites are designed for real time, thus requiring continuous communication. Because of this, questions about radio frequency spectrum partitioning have arisen, since an overcrowded radio frequency spectrum may cause physical interference with adjacent radio frequency signals, making space traffic management a critical issue [29; 30]. The regulatory aspects of space traffic management are inadequately covered because of the emphasis on acquiring any available orbital slots. This is because interferences that affect other operators that may be approaching a target orbit or de-orbiting at the end of a satellite's life are not given sufficient consideration. With the increase in the number of satellites and constellations, many interferences may occur, like the interference of Earth observation and overcrowding, among others.
# Enhancing Feature Selection for Imbalanced Alzheimer's Disease Brain MRI Images by Random Forest
## 3 Design of Imbalanced AD Medical Data Analysis Approach  
In this section, the proposed method will be described in detail. The overview of the proposed classification framework for imbalanced brain MRI image data is illustrated in Figure 1. The process is as follows: Firstly, collect MRI images from the ADNI database and conduct initial pre-processing such as gradient correction, non-uniformity correction, intensity unevenness correction, and scaling correction. Secondly, perform multi-type feature extraction and fusion. Thirdly, propose a new feature selection algorithm based on the random forest to obtain the optimal feature subset. Finally, classify images from the ADNI database by using classifiers.  
In research on the current brain medical image feature extraction technologies, it can be found that the feature fusion method can retain more details of the image; therefore, this paper employs the feature fusion method to fuse the morphological features and texture features of the MRI images.
## 1 Introduction
### Problem and Scope
According to its NLOS identification result, a flexible and practical NLOS coping method is supposed to be used. Among the traditional NLOS coping methods mentioned above, there are two main ideas. The first mainstream idea is to implement an algorithm or compensation function based on the identification results of NLOS acoustic signals, so as to complete the compensation for the negative effects caused by NLOS scenarios. This method is tough to implement and is not easy to adjust or implant. Up to now, there has been no unified compensation formula or method applicable to most flexible NLOS scenarios. The second mainstream idea is to complete the necessary processing only for LOS signals according to the NLOS identification results and completely discard all NLOS signals. This method is relatively easier and more flexible to implement and can be applied more precisely in complex scenarios. Before that, the NLOS chirp signal feature extraction algorithm based on acoustic localization signals was presented in [20], which is quite different from other feature extraction algorithms oriented to other voice or sound signals. Its feature extraction algorithm has been proved to be more effective when coping with multipath effect and NLOS situations on a transmission path compared with Mel Frequency Cepstral Coefficient (MFCC) or Linear Prediction Cepstral Coefficients (LPCC). According to this NLOS identification result, the system will rearrange the system's key process, and it is a reasonable choice to apply a compensation method or correction mechanism under these circumstances. In addition, to cope with the requirements of the dual-receiving process, the new acoustic anchor structure was also redesigned in the flexible NLOS scenarios. Finally, the effects of NLOS identification algorithms and correction mechanisms were tested in man-made complex and flexible NLOS scenarios. In brief, our contributions can be summarized as follows:  
1. A novel dual-receiving structure is introduced to build our acoustic signal anchors for indoor localization systems. Meanwhile, according to the requirements of the interactions between the acoustic anchor structure and the system's main task, we also design and implement our own acoustic signal dual-receiving process based on the adaptive RSS selecting mechanism and finish the indoor localization with stronger robustness and mobility. 2. An adaptive method for NLOS indoor localization identification named CTGSA-AFSA is introduced and tested in our man-made complex and flexible NLOS situations. According to the original artificial fish school algorithm (AFSA) method, some updating strategies including adaptive chaotic transformation, adaptive GSA optimization tactics, and energy attenuation model are implemented. These methods are used to energize the performance of the decision tree (DT) model so that the system can obtain a more trustworthy and rapid NLOS identification result. In that case, a more reliable positioning result can be obtained in complex and flexible NLOS situations.
# Passwordless Authentication Using a Combination of Cryptography, Steganography, and Biometrics
## 3 Methods
### User Interaction Flow  
#### 3.3.1 User Authentication  
Before authentication can take place using SA, the account and service (e.g., Ecom) to authenticate must have been added, as described in Section 3.2.3. Assuming this criterion is already met:  
* User visits the Ecom login page and enters their username, which is sent to the Ecom server.
* The Ecom server checks its database to see if the username exists and is associated with a public key. If it exists, the public key for that username is retrieved and sent from the Ecom server to the SA server.
* The SA server generates a random string as an initial response to the Ecom server; the Ecom server will display the string to the user requesting login. As in previous communication, the string is encrypted before it is sent to the Ecom server. Simultaneously, the SA server extracts the DN-ID associated with that account public key and sends a notification to the device.
* The user receives the notification prompt on their device and is requested to enter the random string displayed on the screen where they are requesting login.
* Once the user enters the random string into the provided area in the app, biometric authentication is sought to approve the request, and the response is sent to the SA server.
* The SA server compares the input from the user with the string that was generated; if there is a match, as in Figure 7, the SA server informs the Ecom server that the request can be approved, and the Ecom server handles routing the user to their account. If there is no match, the SA server informs the Ecom server to deny the login request.
# Sino-InSpace: A Digital Simulation Platform for Virtual Space Environments
## 4 Design of Platform Application Modes and Case Study
### Application Directly
#### 4.1.2 Visualization and Deduction  
Sino-InSpace provides a flexible and visible platform for the massive achievement not only on earth but also on other planets. In support of a perfect time-space datum framework, stars, planets in the solar system, and geographical and space environment data are integrated, organized, and displayed as shown in Figure 12. Excellent data organization and a good visualization engine guarantee the fluent running of the platform. The time delay mainly originates from the initial data loading and the real-time calculation (e.g., orbit prediction and empirical space environment models). The time required to load the necessary data in the illustrations is no more than 3 s, and the frame rates are all greater than 30 ftps, which is sufficiently satisfactory for observation.  
Advance deductions are often carried out to enhance the understanding of the mission. As shown in Figure 13, a launching mission deduction of the Shenzhou spacecraft was designed. The trajectory and action data of the CZ rocket and manned spacecraft were added to the related object model. Then, the script file was edited and loaded to drive the mission execution, and the viewpoint was switched to the interested perspective. Meanwhile, some illustration and text hints appeared on the screen occasionally.  
Figure 11: The operation window of Sino-InSpace in the application directly mode. (**a**) The main window includes the Scenario Editor, 2D and 3D view, Time Control, and Viewpoint Control; (**b**) Trajectory setting window; (**c**) Geometric model setting window; and (**d**) Action design window.  
Figure 12: Integration and visualization of the constellation and environment data. (**a**) Stars (Tycho-2 catalogue, number: >2.5 million) and planets in the solar system (NASA Jet Propulsion Laboratory Development Ephemeris (JPL DE) 405); (**b**) all named features for the moon (number: 8990) [65]; (**c**) geomagnetic field generated from the Tsyganenko 96 model [66], which includes the solar-wind-controlled magnetopause, region 1 and 2 Birkeland currents, and the interconnection of the magnetospheric and solar wind fields at the boundary; and (**d**) geographical data from the southeast area of China (image resolution: 30 m, DEM resolution: 90 m, data amount: >200 GB).  
Figure 13: Launching mission deduction of the Shenzhou spacecraft. (**a**) Rocket firing. The illustrations introduced the stage name and the capacity of the CZ rocket. (**b**) Rocket booster separation. The separation action executed 114 s later; (**c,d**) the process of solar panel expansion and orientation. The solar panel as a component of the spacecraft model was translated and rotated according to the action sequence setting.
###### Abstract  
Background: Biological molecules such as therapeutic proteins and peptides have provided ample opportunities for further improvements in health and wellbeing. However, such biomacromolecules face stability challenges regarding premature processing and digestion, whenever any enteric delivery route is considered. Hence, oral guar films entrapping peptide-containing chitosan microparticles have been developed as a new delivery system to carry and protect therapeutic relaying peptides. Results: The composite films were characterized regarding physicochemical properties using FTIR as well as peptide encapsulation efficiency, cytotoxicity, and peptide permeability through buccal and intestinal cell-based models. The composite films with 0.18% (_w/w_) of peptide demonstrated ca. 0.63% of peptide loading efficiency into the chitosan microparticles and to be safe for buccal and intestinal epithelial cells up to 24 h of contact. The permeability assays through TR146 cells to mimic buccal mucosa epithelium and Caco-2/HT29-MTX to mimic duodenum conditions showed that the incorporation of peptide chitosan microparticles into guar-gum oral films offered a faster permeability, when compared with the free peptide and peptide-chitosan-microparticles-loaded chitosan. Conclusion: This study suggests that peptide-loaded chitosan microparticles into guar-gum oral films might be a promising carrier for enhancement of the buccal and intestinal absorption of a relaxing peptide.  
biocative peptides; oral delivery system; chitosan; oral films +
Footnote †: journal: Physics Letters  
1 Research Centre for Human Development, HNL/CEDH--Human Neurobehaviour Laboratory, Universidade Catolica Portugues, Rua de Diogo Botelho 1327, 4169-005 Porto, Portugal 12 CbQF-Centro de Biotecnologia a Quimica Fina--Laboratorio Associado, Escola Superior de Biotecnologia, Universidade Catolica Portugues, Rua Diogo Botelho 1327, 4169-005 Porto, Portugal 2
# Conductive Textiles for Signal Sensing and Technical Applications
## 2 Materials Used to Impart Conductivity on Textiles
### Conductive Metals
#### 2.2.3 Copper Nanoparticles (CuNPs)  
CuNPs have heat transfer properties such as high thermal conductivity, low preparation cost, antibacterial efficiencies, catalytic activity, and electrical and optical properties. They are produced by the chemical reduction method [51]. The surface of the textile fabric can be covered with a layer of densely packed Cu particles after ELD [55]. Cu-coated textiles can show a bactericidal effect [56]. The antibacterial property is important because electromagnetic interference (EMI) shielding fabrics are excellent media for microorganism growth [57].
## 3 Results and Discussion
### Further Experimental Validation
The model identified specific conditions that optimize these responses, and the observed experimental results validate these predictions. The close agreement between the predicted and real values of WL% and SG% underlines the model's robustness and reliability. Moreover, the model suggested that maximum glycerol concentration and temperature, combined with optimal immersion times, would yield the best results for both water loss and solid gain. Experimental validation confirms this by showing that longer immersion times were beneficial, albeit with a plateau at certain durations, which the model also hinted at through the prediction of diminishing WL and SG values beyond a certain time point.
## 2 Preliminaries  
In this section, we briefly introduce the polar coding method and existing decoders related to this paper for \(PC(N,K+N_{crc})\). \(PC(N,K+N_{crc})\) refers to a polar code of code length \(N\), CRC length \(N_{crc}\), information bit length \(K\), and code rate \(R=K/N\).
# Corrosion-Fatigue Evaluation of Uncoated Weathering Steel Bridges
## 1 Introduction
Meanwhile, the critical pitting flaw size is used to connect the two stages smoothly, beyond which the fatigue process can come into effect as a driving force in crack propagation. In simulating the fatigue-induced crack propagation, the fracture  
Figure 1: Typical fatigue crack in uncoated weathering steel bridges. mechanics-based NASGRO equation, which is proposed by the NASA [11; 12], is applied to consider the propagation behavior of short cracks. In addition, a competition-based criterion has been introduced, in which the corrosion process and fatigue process are competing in terms of the propagation rate and the C-F process is controlled by the one with the higher rate. Based on the above method, the service life can be predicted at the two stages, respectively. Through combining the life at the two stages, the whole service life under the C-F process can be solved. The proposed model has been carefully verified through the experimental data collected from several publications. With the validated model, sensitivity analysis has been made on the crucial parameters, including the stress range, stress ratio, corrosive environment and average daily truck traffic (ADTT). The result reveals the influence of different factors on the C-F life of UWS bridges. Meanwhile, the proposed method can be referred to in the fatigue design of UWS bridges. Moreover, this study also highlights the advantage of UWS bridges in service life under corrosion and fatigue when compared with the traditional steel bridges.
# Unveiling the Landscape of Operating System Vulnerabilities
## 5 Findings and Discussion  
### Sampling of Vulner OS Categories, OS Versions, and Vendors  
Figure 3 presents a comparative bar chart depicting the highly vulnerable OS categories using our OS_CAT dataset with 310,429 distinct data points. The chart reveals that the top 10 vulnerable OSs consist of a diverse range of OS types encompassing desktop, mobile, server, and TV OSs. The OS categories Debian Linux, Ubuntu Linux, Fedora, and openSUE have significant numbers of vulnerabilities, highlighting the importance of proactive security practices in the Linux ecosystem. The OSs in the Windows family, i.e., Windows and Windows Server, have 4646 and 3942 vulnerability entries, respectively. The Apple OSs, namely macOS, iPhone OS, and tvOS, also fall in the top 10 list. The OS categories Android and iPhone OS demonstrate vulnerabilities in mobile OSs. With the increasing use of mobile devices, it is crucial to address these vulnerabilities promptly through regular updates and user awareness.  
In addition, Figure 4 showcases the number of vulnerabilities reported for specific OS versions under corresponding OS categories, as highlighted by the respective colors, utilizing our OS_VER dataset with 465,084 data points. Surprisingly, Debian Linux 9 and Android 10 have comparatively low vulnerability counts, contrasting their top vulnerable respective OS categories in Figure 3. The chart shows that the top vulnerable OS versions are Windows 10 and Windows Server 2008. The higher number of vulnerabilities in popular desktop OSs like Windows and macOS, as well as mobile OSs like Android and iOS, suggests that attackers may focus their efforts on these widely used platforms due to the potential impact and larger user base.  
Figure 3: Top 10 highly vulnerable OS categories based on all-time (1999–2022) vulnerability reports of OS categories using the OS_CAT dataset with 310,429 data points.  
Similarly, Figure 5 shows the top 10 vendors with a high number of vulnerable products. We found that Redhat topped our ranking, with a total of 11,498 reported vulnerabilities, followed by Apple with 10,885 reported vulnerabilities. The presence of a diverse range of vendors, including Redhat, Apple, Microsoft, Debian, Google, Fedora Project, Canonical, openSUE Project, Cisco, and Huawei, among the top 10 with vulnerable products highlights the need for comprehensive vulnerability management across various vendor ecosystems. The inclusion of vendors like Redhat, Debian, Fedora Project, and openSUE Project in the top 10 underscores the importance of addressing vulnerabilities in open-source software. The collaborative nature of open-source projects requires active community involvement to identify and remediate security vulnerabilities promptly.
# A High-Resolution SAR Focusing Experiment Based on GF-3 Staring Data
## 2 Focusing Experiment Based on GF-3 Staring Data  
In practice, to acquire operational SL-mode products, GF-3 works in the sliding spotlight mode during which the antenna steers at a VRP below the ground to increase the integration time. The significant distinction between SL mode and ST mode in this experiment is that in ST mode the VRP is located within the imaged scene on the ground (i.e., the antenna is always pointing at the same scene during the accumulating time). Table 1 summarizes some parameters of GF-3 in SL and ST modes. The resolution in slant range can be derived from the bandwidth of the pulse signal, but its projection on the ground--ground resolution--changes with the incidence angle as shown in Figure 1a. As we can see, GF-3 can get a ground resolution range within [0.815, 1.826] m. The resolution in azimuth changes with the antenna steering angle range as shown in Figure 1b. As we can see, GF-3 can get the highest theoretical azimuth resolution of about 42 cm, with a rectangular weighting Doppler spectrum, when the steering angle range is 3.8\({}^{\circ}\).  
However, higher resolution means more difficult processing, and the performance of traditional approaches usually is not satisfactory. In order to get qualified images, this experiment made some improvements to the range history model, the imaging algorithm, the stop-and-go approximation, and the antenna modulation. The details of this experiment can be found in the below subsections.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Observing Mode** & **Incidence Angle (\({}^{\circ}\))** & **Az. Resolution (m)** & **Polarization** & **Bandwidth (MHz)** \\ \hline SL & 20–50 & 1 & HH & 240 \\ ST & 20–50 & 0.45 & HH & 240 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Some parameters of Gaofen-3 (GF-3)’s sliding spotlight (SL) and staring spotlight (ST) modes.  
Figure 1: The resolution in ST mode. (**a**) The ground resolution versus the incidence angle; (**b**) The azimuth resolution versus the scan angle range.
## 5 Conclusions  
The first DBSCAN-BNLE was experimentally demonstrated for 16 QAM at 50 km. Two novel DBSCAN methods were proposed, in which the \"un-clustered\" noisy constellation points were processed using (1) K-means and (2) the minimum distance between an unlabelled point and the clustered points. Compared to linear equalisation, method-2 improved the Q-factor up to 8.8 dB by combating SPM. Method-2's ability for overlapping clustering resulted in Q-factor improvement over method-1 and K-means (exclusive clustering), when vastly rotated clusters of nearly elliptical form occur. Once optimised, DBSCAN proved to be a robust BNLE for very strong nonlinear phase noise.  
In future work, inter-channel nonlinear effects, such as four-wave mixing and cross-phase modulation, will be tackled using the proposed machine learning algorithm in a super-channel transmission scenario that incorporates many wavelength channels.  
Conceptualization, E.G. and Y.L.; methodology, E.G.; software, E.G. and Y.L.; validation, M.J., S.O., K.M., P.F.W. and L.P.B; formal analysis, M.J.; investigation, E.G.; resources, L.P.B.; data curation, K.M. and P.F.W.; writing--original draft preparation, E.G. and Y.L.; writing--review and editing, E.G., Y.L., S.O., and L.P.B; visualization, E.G., Y.L. and S.O.; supervision, L.P.B.; project administration, E.G. and L.P.B.; funding acquisition, E.G. and L.P.B.  
This work was supported by the Science Foundation Ireland through grant numbers 13/RC/2077, 12/RC/2276, 15/US-QC/I3132, the HEA INSPIRE Programme, and the EU/EDGE Marie Curie programme with grant number 713567.  
The authors declare no conflict of interest. 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, nor in the decision to publish the results.  
Figure 5: Received constellation diagrams for (**a**) DBSCAN 1 st loop (left), method-2/2 nd loop (right) at +10 dBm of LOP (OSNR = 15 dB); and (**b**) DBSCAN method-1 (left), method-2 (right) at +16 dBm of LOP (OSNR = 30 dB)[PERSON]