esa-sceva/satcom-chunk-collection huggingface dataset:
# Automatic Generation of Guidance for Indoor Navigation at Metro Stations
## 2 Related Work
### Indoor Navigation for People with Special Needs  
The seemingly simple tasks described in the previous section can pose problems for people who have poorer spatial orientation. Specific conditions inside transit buildings, such as limited visibility, distracting ambient noise, and crowds of people, make it difficult for some users to move efficiently. Reaching a building through the most convenient entrance and then navigating around to proceed to a platform at a station or a gate at an airport is particularly difficult for people with disabilities. Typical problems faced by visually impaired people at metro stations and approaches to solving them are presented in the literature [26, 27]. In recent years, artificial intelligence methods have been used to aid indoor navigation. In addition to improving position accuracy [28, 29, 30], deep learning and reinforcement learning methods can facilitate the movement of visually impaired people through obstacle detection and landmark identification [31, 32] or spatial analysis for localisation [33].  
Indoor navigation systems for wheelchair users have been the subject of research on requirements and general conditions of navigation [34, 35, 36]. Similarly to the research on the navigation of visually impaired people, deep learning and reinforcement learning methods can be used for the identification and avoidance of obstacles [37] and for recognising landmarks [38].  
The conclusions of these studies clearly indicate that systems should be designed with the specific type of user in mind, and paying attention to the specific limitations they have. User expectations must be considered not only during the creation of the navigation guidance but also at earlier stages of building the system, starting with the modelling of the spatial data.
## 5 Results and Discussion
### Results from Consideration Propensity Model  
Consideration, indicating potential demand in this study, is defined as a binary variable, and therefore, its propensity is modeled using a binary logit model specification, discussed in Section 4.2. In addition to the usual logit and probit models, other error term assumptions representing thick-tailed error term distributions, Cauchy, and asymmetric distributions, namely log-log, complementary log-log, and skewed logit models, were also tested [40]. The results presented in Table 3 show that the binary logit model provides a better fit compared to alternative functional forms. The log-likelihoods were as follows: logit model = \(-\)414.73, Cauchy = \(-\)416.52, log-log = \(-\)416.19, and complementary log-log = \(-\)415.83). Hence, only the results from the best model, i.e., the logit model, are presented in detail in the subsequent subsections.  
To validate the metro consideration model, the dataset was randomly split into 70% training and 30% testing subsets. The goodness-of-fit measure, log-likelihood (LL) per observation, was compared between the test model (calibrated on the test data) and the train model (calibrated on the train data) when both were applied to the test data. The absolute percentage difference in performance was 13.56%, with the test model achieving an LL per observation of \(-\)0.44, while the training model achieved an LL per observation of \(-0.51\) on the test data. This difference was within acceptable limits, indicating adequate model validity.  
The results related to goodness-of-fit and the statistical comparison of segmented and unsegmented consideration models based on personal mobility resources are presented in the following subsection. The differences across segments in the role of influential factors related to multimodal connectivity and accessibility variables are discussed in Section 5.1.2. Section 5.1.3 highlights the potential bias from neglecting heterogeneity across segments.
## 5 ESTCube-Luna Preliminary Mission Requirements and Platform Design Solutions
### Communication (COM)
#### 5.4.2 High-Speed Communication (HSCOM)  
The Ventspils International Radio Astronomy Centre (VIRAC) in Irbene, Latvia, includes two radio telescopes--RT-32 and RT-16--that have parabolic dishes of 32 m and 16 m  
Figure 12: Proposed antenna solutions for ESTCube-LuNa. EnduroSat X-band patch antenna for data downlink and ranging (**left**) and ISISPACE turnstile antenna for UHF telemetry and command (**right**).  
in diameter, respectively (see Figure 13). The telescopes are being repurposed to allow for satellite uplink and downlink communications. We assume RT-16 as the baseline antenna for data downlink. RT-32 can be employed for the ranging experiment (RE), as well as for emergency needs when RT-16 is not available. The repurposed radio telescopes for communications and ranging is the primary means of ESTCube-LuNa to operate independently of space agency DSNs.  
ESTCube-LuNa is designed to use the X-band 8400 MHz frequency band for high-speed downlink. VIRAC 16 m ground station can provide a maximum gain of 58.9 dBi with a total cryogenic receiver gain of 90 dB. Equipped with multiple directional antennas on different cubesat sides, the HSCOM includes antenna switches to establish a line-of-sight communication with the Earth. To minimise the nanospacecraft surface area taken by the patch antennas (for better power production), our preliminary design includes Endurosat X-band patch antennas, just one quarter of a cubesat unit in surface area (see Figure 12). We place two pairs of patch antennas on two sides of the nanospacecraft for two-way communications and ranging. Depending on the spin plane of the E-sail, directional communication sessions will be available only during the times of the month when Earth will cross the beam of the directional antenna.  
For ranging experiments, it is necessary to develop new capabilities, especially in terms of the space segment. The Iris deep space transponder by NASA JPL in the US [51; 52] includes deep space communications and ranging functions, but it is not available for Europe-based projects like ESTCube-LuNa.  
As discussed in Section 2.3, the ESTCube-LuNa ranging experiment is required to determine accumulated orbital changes in the range of a hundred of seconds in the orbital period. Our initial analyses suggest that for a simplified experiment, the narrow-band ranging signal can be injected into the communications' downlink signal. The most critical requirement originating from the ranging experiment is the need for a coherent frequency conversion chain in the communication hardware. The RF experiment also requires a full-duplex radio capable of receiving and transmitting at the same time, such that we can lock the transmitter carrier to the received carrier with a constant ratio. Special care must be taken in implementing duplex filters and isolators for reliable operations.
## 4 Performance Results
### Performance Indicator
#### 4.1.2 Accuracy Score  
The accuracy score is a numerical value representing accuracy in classification. The formula for calculating the accuracy score is as follows.  
It represents the actual accuracy predicted by the model and represents the proportion of true positives and true negatives in the entire data set. In the case of the accuracy score, if the inconsistency of the data set distribution is too great, it can actually be a meaningless number. Therefore, it is necessary to match the distribution of data set labels.  
\[Accuracy=\frac{TP+TN}{TP+FN+FP+TN} \tag{9}\]  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Hyper Parameter** & **Range** \\ \hline Gamma & (0, 1) \\ Learning rate & (0.01, 1) \\ Max depth & (5, 20) \\ Number of estimator & (100, 1000) \\ Subsample & (0.5, 1) \\ \hline \hline \end{tabular}
\end{table}
Table 13: Hyperparameters used for Bayesian optimization.  
\begin{table}
\begin{tabular}{c c c} \hline \hline  & **Positive (Model)** & **Negative (Model)** \\ \hline Positive (Answer) & True Positive (TP) & False Negative (FN) \\ \hline Negative (Answer) & False Positive (FP) & True Negative (TN) \\ \hline \hline \end{tabular}
\end{table}
Table 15: Confusion matrix.
# The Correlation Factors and Mechanisms of Diffusion for P and S in the Cu Single Crystal
## 4 Discussion
The diffusion of these substitutional impurities requires a vacancy and the symmetry of the matrix-impurity complex is lowest when the vacancy is the nearest neighbor to the impurity. When bonding with transition metals, S is known to prefer lower symmetry arrangements and larger volumes of the atomic sites when compared to P. This leads to an energetic gain that was reflected in the two important parameters that affect both the diffusion mechanism andthe corresponding diffusion coefficient: (a) the binding energy between the S-vacancy (\(-0.432\) eV), which was larger when compared to the P-vacancy (\(-0.229\) eV); and (b) in the considerably smaller \(\Delta E_{a}\) values for the jumps \(w_{2}\) and \(w_{4}\) for S when compared to P. This, in turn, led to attempted frequencies for these jumps which were orders of magnitude larger for S than for P. From a detailed electronic structure analysis of the bonding between S and Cu, and P and Cu [26], we found that S had both more populated bonding states and less populated antibonding states than P. This explains both the stronger bonding with the Cu matrix and the lower \(\Delta E_{a}\) value for diffusion because of less friction between S and the matrix when compared to P and the matrix at the transition state. Both the geometric and electronic structural features explain the differences in the diffusion coefficients for these impurities: S diffuses faster than P in the Cu single crystal and it is also known to be a faster diffuser in polycrystals.
## 3 O-RAN with 200 m FSO Link
### The 200 m FSO Link Backhaul for O-RAN with 4 m Fronthaul for Indoor Network
Figure 10a illustrates the uplink throughput performance, and it can be found that it was lower than the case of the O-RU antenna directly connected to the cell phone, which is because the position of the CPE was not perfectly matched with the pointing of the antenna. Additionally, due to the multipath effect, the throughput varied but mostly stayed around 30 to 40 Mbps. The uplink throughput significantly degraded when the O-RU was far from the CPE and the CPE was distant from the cell phone; this signal degradation caused by the longer distance is expected. In the downlink throughput performance, as shown in Figure 10b, when the distance between the CPE and O-RU antenna was 0 m, the result mirrors that of the case of the O-RU antenna directly connected to the cell phone. However, when the distance between the CPE and O-RU antenna was 20 m and 40 m, the performance of downlink throughput was weakened due to signal degradation. The outcomes of jitter and ping, as depicted in Figure 10c,d, exhibit striking similarity to those observed when the cell phone was directly connected to the O-RU antenna. An exception can be noted in the ping, which demonstrated a marginal increase when the CPE was positioned 40 m away from the O-RU antenna and the cell phone was situated 20 m from the CPE. Since the CPE was 40 m away from the O-RAN, the ping was slightly larger, which made the corresponding jitter abnormal. Figure 9: O-RU utilizes 4 m fronthaul for handset direct network performance measurement. (**a**) shows up/downlink throughput; (**b**) shows jitter and ping. The box-and-whisker plot uses 25% fractions and 75% fractions, and coef is 1.5.
# Performance Analysis of Hybrid PDM-SAC-OCDMA-Enabled FSO Transmission Using ZCC Codes
## 6 Simulation Results  
The computed results for PDM-SAC-OCDMA-enabled FSO transmission are given in this section. The parameter values considered during simulations performed on Optisystem software are given in Table 4[5; 21; 24; 28].  
Log(BER), Q-factor, various FSO spans, and eye diagrams are considered for evaluating the performance of our proposed model. The results are divided into four parts as follows.
###### Abstract
Previous studies have demonstrated clear advantages of social media data in revealing public perceptions, usage patterns, and socio-cultural values of CES. For instance, [PERSON] and [PERSON] [15] conducted sentiment analysis on images and user comments from the Dianping platform. They explored tourists' perceptions of cultural services in Shanghai's urban parks, finding that tourists' emotional responses closely correlated with park landscape design and spatial arrangement. Similarly, [PERSON] et al. [16] and [PERSON] et al. [17] analyzed user-generated data from Twitter and Flickr. They quantified the performance of urban parks in providing cultural services, including esthetics, social interactions, and leisure functions. These studies illustrate that social media data can effectively reflect real-time public perceptions and dynamic changes in cultural services. Thus, they provide valuable data support for urban planning and public space management. Nevertheless, current research has mainly focused on Europe, North America, and mainland China. Studies specifically examining CES in Macau's urban parks remain relatively scarce. Macau is a city with a long history and notable cultural diversity. Its urban parks provide significant esthetic, recreational, and educational benefits, and also play a vital role in preserving cultural heritage [18; 19]. For instance, Lou Lim Ieoc Garden and Monte Fort in Macau are important recreational spaces for residents. These parks also reflect Macau's distinctive integration of Chinese and Western cultures. However, current research primarily focuses on evaluating ecological functions in urban parks. In comparison, studies addressing cultural services are relatively scarce. Traditional methods, including questionnaire surveys and field observations, are predominantly employed. However, these methods have limitations in comprehensively capturing the dynamic characteristics and spatial distribution patterns of cultural services in parks. Social media platforms serve as important channels for Macau residents and tourists to express their experiences and share perceptions of landscape values. Thus, social media data provide a novel perspective for systematically evaluating CES in Macau's urban parks. Therefore, this study aims to establish a quantitative evaluation system of CES based on social media data from a cultural heritage perspective. This system is utilized to systematically assess the characteristics and spatial distribution of cultural ecosystem services in 12 major urban parks on the Macau Peninsula. Natural language processing techniques and spatial analysis methods are combined to extract emotional expressions and spatial characteristics from user-generated content. This approach highlights differences in CES dimensions among Macau's urban parks and identifies the factors influencing these differences. This study provides scientific support for urban park planning and cultural heritage conservation in Macau. Additionally, it offers a novel theoretical and practical framework for future quantitative CES research.
## 3 Results
### Limitations and Effectiveness of Combining VR and FES
#### 3.5.2 Limitations of Combining VR and FES  
1. Small Sample Sizes and Study Designs  
One common area of improvement across the studies we reviewed is the small sample sizes. These limited sample sizes make applying the findings to a broader population difficult. For example, [PERSON] et al. [32], 2022, only included 13 participants, while [PERSON] et al. [34], 2021, had 30 participants. The small sample sizes reduce the statistical power and the ability to make general conclusions. To address this issue, future research should focus on larger, multi-center, randomized controlled trials to validate these findings and gain a more comprehensive understanding of the effectiveness of the combined VR and FES approach.
2. Long-term Efficacy and Follow-up  
Another significant limitation is the need for long-term follow-up data. The studies reviewed primarily focused on short-term outcomes, with few providing insights into the sustainability of improvements. Longitudinal studies are necessary to determine whether the benefits of VR and FES are maintained over time and to assess the long-term impact on functional independence and quality of life.  
3. Standardization of Protocols  
The VR systems and FES parameters used across different studies vary considerably. For example, the VR scenarios, frequency, intensity, and pulse width of FES varied significantly between [PERSON] et al. [32], 2022, and [PERSON] et al. [33], 2018. This lack of standardization makes comparing results and drawing definitive conclusions difficult. Developing standardized intervention protocols would enhance the reliability and reproducibility of research findings. Integrating VR and FES into standard rehabilitation protocols could potentially transform post-stroke rehabilitation by providing engaging and effective therapy options.  
Potential for Cybersickness and Discomfort  
It is important to note that VR can sometimes lead to cybersickness, characterized by symptoms such as nausea, dizziness, and visual discomfort. This potential discomfort can be a limiting factor for patient participation and engagement [42]. While not extensively reported in the reviewed studies, it is crucial to acknowledge that designing more user-friendly and comfortable VR systems remains a potential challenge that needs to be addressed to ensure the successful implementation of the combined VR and FES approach. It is essential to highlight that those researchers did not observe any adverse reactions or dropouts attributed to challenges in using VR technology devices. These issues can be effectively alleviated with appropriate design and diligent patient monitoring.
# Optimization of DG-LRG Water Extraction Algorithm Considering Polarization and Texture Information
## 3 Optimized Local Region Growth Algorithm Considering Polarization and Texture Information  
This article proposes an optimized local region growth algorithm that takes into account the polarization mode and texture features of SAR images for fast water extraction, denoted as DG-LRG. The main process of this method can be divided into four steps: the first step is to perform rough water extraction based on threshold segmentation on pre-processed dual polarization GF-3 images; the second step is to select seed points for regional growth based on the rough water extraction (see Section 3.2 for details); the third step is to combine polarization methods and texture features to locally optimize the region growth using certain criteria (see Section 3.3 for details); and the fourth step is optimizing the image segmentation results of regional growth by combining morphological theory and external geographic information data to obtain the final water extraction results. The implementation process is detailed in Figure 3.
## 5 Conclusions, Limitations and Future Work  
In this paper, we proposed an approach to detect and localize forgeries in images-based on a visual cryptography watermarking scheme. The CASIA V 1.0 and SIPI datasets were used to test the robustness and efficacy of this approach. Several known attacks, including compression, salt and pepper noise, Gaussian noise, Poisson noise, speckle noise, sharpen, median filtering, rotation and scaling were applied to the digitally forged images in these datasets. Many experiments were conducted with the aim to evaluate the forgery detection and localization capability of the mentioned approach. We concluded that our scheme has good robustness against the aforementioned attacks, and it outperformed the compared state-of-art approaches. Furthermore, one characteristic that was recognized in the proposed approach is that all of the recent related works are used for image copyright protection only, but our approach is the first one proposed to detect and localize forgeries using a visual cryptography-based watermarking scheme. Hence, it provides a good alternative approach for image forgery detection and localization, and it can be used for image copyright protection. The limitations of the proposed approach can be listed as follows: (1) because our proposed approach is a block-based approach, there is a probability of the inclusion of some of the pixels of neighboring blocks with the forged blocks; (2) the proposed approach works fine with geometrical attacks to some extent; however, it begins to suffer whenever the scaling factor and rotation increase in large amounts. As a future work, the researchers plan to improve the proposed approach by using segmentation instead of block division for images, and also to use other available tools to increase the robustness of the proposed approach.  
Conceptualization, M.Z.S. and A.J.A.; methodology, M.Z.S. and R.Y.; software, M.Z.S.; validation, A.J.A. and R.Y.; writing--original draft preparation, M.Z.S. and A.J.A.; writing--review and editing, R.Y. and A.J.A.; visualization, M.Z.S. All authors have read and agreed to the published version of the manuscript.  
There was no funding available for this research.  
The datasets used in this research are publicly available. The first dataset, CASIA V 1.0, is available at the following link: [[https://github.com/namtpham/casial](https://github.com/namtpham/casial)]([https://github.com/namtpham/casial](https://github.com/namtpham/casial)) groundtruth. The standard images in the second SIPI dataset are available for download from the following link: [[http://www.imagprocessingplace.com/root_files_V3/image_databases.htm](http://www.imagprocessingplace.com/root_files_V3/image_databases.htm)]([http://www.imagprocessingplace.com/root_files_V3/image_databases.htm](http://www.imagprocessingplace.com/root_files_V3/image_databases.htm)).  
We would like to thank everyone who helped us in this research.  
We declare that there is no conflict of interest of any kind with other research.
# Analysis of Controllability in Cyber-Physical Power Systems under a Novel Load-Capacity Model
## 3 Fault Propagation of CPPS under Cascading Failure  
### Initial Load and Capacity Model  
A cyber-physical power system is a heterogeneous network formed by the coupling of a power grid and an information network. Therefore, many previous studies have treated the power grid and the information network equally, and the load-capacity models have also been treated as homogeneous [17]. As a result, the power grid and information network are considered separately in the CPPS. Each network's capacity and load are defined independently. When describing the cascading failures in chemical process systems, the load-capacity model proposed by [PERSON] [11] is often employed, where the node capacity is linearly related to the initial load. Building upon this, a load-capacity model for a cyber-physical power system is proposed in this paper. However, in contrast to the previous model, this study introduces a load-capacity model based on electrical betweenness and information entropy, which better aligns with the real-world scenarios of CPPSs.