esa-sceva/satcom-chunk-collection huggingface dataset:
## 3 Validation by the Simulated Case
### Images Design  
Designing the images involves two key considerations. First, the simulated cases need to be comparable to typical real bed-load movement in common open-channel flow experiments in terms of particle characteristics (size, shape and color), bed configurations, and motion kinematics (entrainment, displacement, speed, etc). Second, the simulated cases cover a relatively broad range in the displacement between two successive images, thus revealing the influence of the measurement.  
The image is 250 \(\times\) 250 pixel2 in size, and there are 8 \(\times\) 8 particles in length, width evenly distributed across one image as shown in Figure 8a. There are 500 image series with the same particle distribution. The particle, irregular in shape, is designed by superimposing two or three smaller circles (3-5 pixels in diameter) onto a bigger circular particle (11-16 pixels in diameter), as illustrated in Figure 8b. There are 12-15 pixels between the centers of the bigger and smaller circle. Moreover, the combined irregular particle has an average equivalent diameter \(D_{s}\) = 30 pixels. The lowercase represents instant value, and uppercase represents average value in this study.  
Footnote 2: footnotemark:  
Particle motion is simplified into an entrainment-flight-deposition pattern. The number of entrained particles follow a negative binomial distribution, as suggested by [PERSON] (2010) [33] and entrained randomly over the image. Based on this, we set the total number of active particles between two images to be \(N_{s}=590\pm 30\). If a particle is entrained, particle placed on its position in the next image will appear instantly. The flight of a particle across two successive images is characterized by time duration and traveling displacement. To investigate the influence of measurement frequency, we set the duration to be constant at one second and used a series of velocities, thus varying the displacement of a moving particle between two successive images. This processing means is equivalent to varying the sampling frequency in a measurement of bed-load motion at a fixed velocity.  
Four cases were considered in terms of streamwise velocity, i.e., \(U_{s}\) = 0.25\(D_{s}\), 0.5\(D_{s}\), 0.75\(D_{s}\) and \(D_{s}\) in a time interval, as shown in Table 1. Note that the velocity is equal to displacement in pixel as the time interval is set to be 1 s. The spanwise velocities vs. in a time interval is set to follow normal distribution N(0, \(U_{s}\)/5). The flight length and time are set to be \(L_{s}\) = 5\(U_{s}\) and \(T_{s}\) = 5 s, respectively. Note that the range of \(L_{s}\) is broad enough to cover commonly encountered cases in open-channel flow [11].  
Figure 8: Two consecutive simulated images, (**a**) first simulated image, (**b**) second simulated image. The red points represent the active particles. The solid red circle and dotted red circles mean the combination of one particle.
# Freeform Wide Field-of-View Spaceborne Imaging Telescope: From Design to Demonstrator
###### Abstract  
Wide field-of-view imaging optics offer a huge potential for space-based Earth observation enabling the capture of global data. Reflective imaging telescopes are often favored, as they do not show chromatic aberrations and are less susceptible to radiation darkening than their refractive counterparts. However, the main drawback of reflective telescopes is that they are limited with respect to field-of-view while featuring large dimensions. We propose the use of freeform optics to maximize the field of view while maintaining diffraction-limited image quality and minimizing system dimensions. In this paper, we present a novel freeform wide field-of-view reflective telescope, starting from the optical design, and continuing to tolerancing analysis and manufacture, towards a proof-of-concept demonstrator. The novel telescope features a full field-of-view of 120\({}^{\circ}\) while showing an exceptional spatial resolution of 2.6 km and fitting within 1 CubeSat unit. To the best of our knowledge, this is the widest field-of-view that has ever been realized for a space-based telescope, nearly reaching Earth observation from limb to limb from an altitude of about 700 km. We hope this design paves the way for future space missions enabling improved Earth observation and leading to enhanced monitoring of climate and climate change.  
wide field-of-view; telescope; freeform optics; reflective optics; space instrumentation; demonstrator; Earth observation; climate monitoring
## 2 State-of-the-Art
### Inconsistency Management Approach  
Using a proof-theory-based approach, inconsistency management was defined the first time by [PERSON] et al. [24] for model-driven software engineering. They suggested the use of the first-order predicate logic to identify inconsistencies using an automated theorem-proof, and domain-specific rules were used to solve inconsistencies.  
Thereafter, [PERSON] et al. [5] proposed to use a rule-based approach to identify inconsistencies between various models in the mechatronic systems domain. They proposed a conceptual approach, where they suggested the use of the Resource Description Framework (RDF) as a common representational formalism for models. Then, they used a query language SPARQL (SPARQL Protocol and RDF Query Language) to query for types of inconsistencies.  
Later, [PERSON] et al. [25] applied a synchronization-based approach during the mechatronic design where mappings are defined between models and then used to propagate changes from a principle solution to domain-specific models using TGG rules.  
These approaches have been used for inconsistency management, but they are not well-accepted by the industrial community for many reasons. The proof-theory-based approach can be complex and labor intensive to express models in a logical formalism. The rule-based approach used an incomplete formal system which implies that some inconsistencies may remain undiscovered. The synchronization-based approach enables domain-specific models to be synchronized and checked for consistency management during the overall design process. However, the number and the complexity of the described synchronization rules can be very large due to an increase in the complexity of the interconnection between models.  
The different approaches proposed in this section present some limitations regarding the consistency management process. Therefore, the contribution of this paper is to propose a continuous and automated process for consistency management. Also, we provide the appropriate method and tools to automate the process in mechatronic systems domain.
## 3 Numerical Scheme
### Remarks on Existence and Convergence Theory to the Numerical Scheme
#### 3.1.2 Notes on the Convergence Theory
: _Let \(\mathcal{T}_{n}\) be a sequence of triangulations fulfilling \(\mathcal{N}_{n}\subset\mathcal{N}_{n+1}\) and \(h_{n}\downarrow 0\) as \(n\to\infty\), then the following two statements hold true:_  
1. _Let_ \((y^{(n)})_{h_{n}}\subset X\)_, be the sequence of minimizers of (_8_) generated by the usage of_ \(X_{h_{n}}\) _as discrete subspace_ \(X_{h_{n}}\subset X\) _in the problem formulation of (_4_), then every accumulation point of_ \((y^{(n)}_{h_{n}})\) _is a minimizer of (_4_)._
2. _Let_ \(x^{(n)}_{h_{n}}\subset X\) _be the sequence of limits of the sequences that are generated by the solution of (_13_) on the triangulations_ \(\mathcal{T}_{n}\)_, then every accumulation point of the sequence_ \(x^{(n)}_{h_{n}}\) _is a minimizer of (_4_)._  
Proof. : Let the sequences \(\mathcal{T}_{n}\), \((y^{(n)})_{h_{n}}\subset X\), \(x^{(n)}_{h_{n}}\subset X\) be given, as stated in the corollary. 1. A common result in the context of \(\Gamma\)-convergence, c.f. in [36; 37; 38; 39], is that if \(G_{n}:X\to\mathbb{R}\)\(\Gamma\)-converges to \(G:X\to\mathbb{R}\) then every accumulation point of the sequence of minimizers \((x_{n})_{n\in\mathbb{N}}\), i.e., \(x_{n}\) minimizes \(G_{n}\), is a minimizer of \(G\). Applying this theoretical result to the setup of Lemma 1, one obtains the statement in the corollary. 2. The statement of the lemma directly follows by (i) and by (22). **Remark 6**. : _(i) The convergence proof above is a first result underlining the plausibility of the described discretization of (5). But first note that from the proof of convergence above no rates of convergence can be obtained. From the classical theory, cf. [19; 27; 28; 29], convergence to a certain rate seems to be a valid hypothesis, at least for the linear cases of the PDE (2a)-(2e), cf. [14; 15; 19]._
2. _Note that convergence of the sequence of limits_ \(x_{h_{k}}=\lim_{n\to\infty}x_{h_{k}}^{(n)}\)_, where_ \(x_{h_{k}}^{(n)}\) _is a solution to (_13_), will only be obtained if one accumulation point of_ \(x_{h_{k}}\) _exists, this is fulfilled if (_5_) is uniquely solvable._  
With this result, this section will be concluded. For future discussions, the following discussions have to be made:  
1. The stability and the convergence of the augmented Lagrangian Algorithm 1 is proven in [25; 26], to prove stability and the convergence of Algorithm 1 for the case that is considered in this article the assumptions of the corresponding theorem in [25] have to be verified. 2. The convergence of the quasi-Newtonian scheme (13) has to be discussed in a much more rigorous way than done in Remark 5. 3. Convergence to a certain rate has to be verified for the discretization of (5). 4. As known to the authors, the existence theory, as described in Section 3.1.1, is for the problem (2a)-(2e) incomplete. A careful study of sufficient and necessary condition has to be made.
## 5 VRPs with Synchronization Issues
[61], and [PERSON] and [PERSON] [62], where a last-mile delivery was fulfilled through collaborative truck-drone routing optimization. In this case, trucks were designed to transport both products and drones, and, along their paths, they were allowed to release drones and rejoin them afterward in a different location. This currently hard-to-implement scenario could speed up the delivery process and sidestep the short battery life in drones at the same time. Another solution belonging to the same research stream is that proposed by [PERSON] et al. [63], where the authors tried to find the optimal route for a set of delivery vans with drones or sidewalk robots, i.e., in a system in which there was an independent vehicle that could move on its own and a special vehicle that assisted it. A similar problem was tackled by [PERSON] et al. [64], who approached the two-echelon VRP (2E-VRP)--i.e., two distinct fleets of vehicles were used to carry out deliveries--by considering time windows and synchronization constraints as well. The authors approached the problem by means of an adaptive large neighborhood search (ALNS) and found good solutions in a reasonable time. Another interesting scenario characterized by high synchronization and dynamism was that faced by [PERSON] et al. [65], who analyzed a realistic and novel VRP variant. Their problem considered container transportation throughout a spoke-hub network. These containers were to be relocated from their original location to their destination, and the relocation of the containers was to be performed before a pre-specified deadline. The containers could be transported by different trucks and could be temporarily stored in network hubs before being delivered to their destinations. A truck could transport only one container at a time, and truck drivers were to return to their starting point by the given time. To solve this problem, a DEH was proposed to address the intrinsic dynamism of this time-evolving system. Finally, as proved by [PERSON] et al. [66], healthcare applications may also benefit from algorithms that are able to deal with synchronization issues. In this case, the authors studied a VRP with synchronized visits and stochastic travel and service times, which was formulated as two-stage stochastic integer programming, and they applied the L-shaped algorithm and its branch-and-cut implementation to solve the problem. In addition, an operating room scheduling problem with stochastic durations was formulated and solved.
# Revolution or Evolution? Technical Requirements and Considerations towards 6G Mobile Communications
## 9 Conclusions  
We are currently at the beginning of the early 5G commercial stage, which is touted as causing a substantial revolution--or, at least, evolution--in the mobile wireless communications industry. The revolution aspect of 5G concerns how it \"stretches\" the use cases that previously focused on mobile broadband only into additional use cases: ultra-reliable low-latency communications and massive machine-type communications. Thus, the term \"5G triangle\" was coined by the mobile communications industry.  
Although 5G just launched in some countries and regions and is mostly still in its infancy, researchers and developers are already conducting their studies and experiments on the development of 6G, especially related to new communication techniques and technologies. Sixth generation is the upcoming mobile system which is expected to be released in 2030 and will significantly change in future mobile wireless networks. From this review, it can be observed that the \"5G triangle\" will evolve towards the \"6G hexagon\" by providing additional dimensions to unlock new industrial use cases. Moreover, 6G will provide an extreme data rate and ultra-low latency, which are forecasted at up to 10 Tbps and 10-100 us, respectively. Additionally, it will enhance spectrum efficiency and connection density to 10-100 times higher than 5G. Furthermore, 6G will bring new applications beyond IoE, enabling intelligent IoE and the vision of everything being connected 100% intelligently. Sixth generation is the era of seamless machine-to-human interactions, things intelligence, and unification of the virtual and physical world. The ultra-high reliability, ultra-high flexibility, ultra-high level of privacy and security, and ubiquitous coverage are the primary keys of the 6G vision.  
This paper provides a comprehensive review of 6G technology, including its vision, use cases and applications, technical requirements, and frequency spectra. Additionally, it discusses the key 6G enabler technologies and the crucial challenges that need to beaddressed to realize the 6G commercial systems. Moreover, a comparison between 5G and 6G in terms of the most important KPIs is provided. Finally, this review presents the future directions in 6G technology.  
Conceptualization, S.A. and R.N.; methodology, R.N. and M.B.; validation, M.B., N.F.A. and A.A.-S.; formal analysis, R.N.; investigation, R.N.; writing--original draft, S.A. and I.S.; writing--review and editing, S.A., I.S., M.B., R.N., N.F.A., A.A.-S. and D.N.; visualization, S.A. and R.N., supervision, I.S., R.N., N.F.A. and A.A.-S.; funding acquisition, R.N. All authors have read and agreed to the published version of the manuscript.  
This work was supported by the Air Force Office of Scientific Research: FA2386-20-1-4045 (UKM Ref: KK-2020-007).  
Not applicable.  
The authors declare no conflict of interest.
# Dynamic Nearest Neighbor: An Improved Machine Learning Classifier and Its Application in Finances
## 5 Discussion  
In conducting the experiment, we use the leave-one-out (LOO) validation method, which has the advantage that it is a deterministic method, without random biases [40]. This means that the result will never change, regardless how many times the algorithm is repeated. This validation method consists of taking a pattern from the test set dataset and the remaining of the patterns as a training or learning set. Once the test pattern has been classified, the extracted pattern is returned to the dataset and the following pattern is taken as the test pattern in the next iteration.  
From the analysis of the results in Table 3, it is possible to see really remarkable situations. It is at once obvious that the proposed classifier D1-NN is ranked first in FOUR of the EIGHT datasets (Bank, Bank additional, Iranian credit, and Qualitative bankruptcy). That is, the D1-NN is better than all other classifiers in 50% of the datasets with which the experiments were performed.  
Of the four remaining datasets where D1-NN did not rank first, in no case is it ranked last. It is fair to note that the behavior of the classifiers in the dataset Qualitative bankruptcy is very particular. Certainly, in this dataset, the D1-NN classifier comes first. However, it is not the only one because there are three other classifiers that obtain the same accuracy value, and they also rank first. Those classifiers are: kNN, SVM, and AdaBoost. The parameters of all the compared classifiers are detailed in Table 4.  
D1-NN is the ONLY classifier of the seven compared that ranks first in four of the eight datasets, the next is logistic regression with three first ranks. In this context, it is worth emphasizing the consistency of the results exhibited by the proposed D1-NN classifier. Furthermore, it is important to note that the D1-NN, being a simple classifier, competes successfully with AdaBoost which is not a simple classifier, but an ensemble where many simple classifiers work in a collaborative environment.  
In contrast to the consistency exhibited by the D1-NN classifier, there is one classifier among the six compared, whose behavior is worth mentioning. It is about SVM, which is based on statistical learning theory and optimization of analytical functions, and which is one of the most appreciated models in machine learning, artificial intelligence, data mining and related areas. In the experimental results of Table 3, the SVM model has erratic behavior. On the one hand, it exhibits 100% performance in the credit approval dataset and therefore comes first in this dataset. However, it comes last in five of the eight datasets.
## 3 Data Processing and Analysis for Smartphone Real-Time Kinematic (RTK) Positioning
### Evaluation of Data Processing
Only when the ratio reaches 10.0 or higher do we use the fix-and-hold mode for ambiguity resolution to ensure the reliability of fixed solutions. The corresponding solutions are shown in Figure 10. Compared with Figure 8, the positioning results are smoother after using the fix-and-hold mode. The fixing rate increases to 90.8% and up to 100% after convergence. Therefore, when the fixing rate is not low in the continuous mode, we also apply the fix-and-hold mode to improve the fixing rate.
# A Data Sharing Scheme for GDPR-Compliance Based on Consortium Blockchain
## 4 Specific Implementation
### Data Storage  
We store indexes containing pointers to user's data records in the consortium blockchain, it can be observed from Figure 5 that a data block consists of a block header and a block body. The endorsement signature of the block represents the regulatory node endorsing the Committee.  
If the committee verifies the transaction, it will be recorded on the blockchain. The personal data of the data subject will be encrypted by \(PK_{u}\) before being stored in the off-chain database rather than being directly stored on the blockchain since storing data on the blockchain will not be capable of modifying or deleting the data, which may violate the right of modification and forgetting in GDPR and generate a potential privacy leak.
# Si Photonics for Practical LiDAR Solutions
## 3 Si Photonics for LiDAR  
Si photonics is one type of integrated photonics which often implies monolithic integration of more than one optical element or function on a single chip. The first commercially successful integrated photonics product may be the InP based EML which stands for externally modulated laser or electro-absorption modulated laser. It was developed in the late 1980s [12], commercialized after about 10 years, and is now widely used in many telecom applications. The rise of Si photonics greatly accelerates the pace of photonic integration in terms of integration scale as well as applications.  
Most Si photonics LiDAR solutions focus on automotive applications by providing certain unique value propositions. Therefore, our following analysis is mostly based on the requirement of autonomous driving and ADAS applications. Table 2 summarizes some essential specifications, proposed by a LiDAR company [13], desired by Level 4 and 5 autonomy (i.e., no human intervention) which is defined by the international Society of Automotive Engineers (SAE) J3016.  
The 200 m range is estimated from the braking distance of about 100 m at 70 miles per hour (MPH) on wet pavement road, computer reaction distance and some margins. Some argue 300 m may be needed for heavily loaded tracks or slippery road while some adopt less than 200 m for low speed vehicles, e.g., shuttle buses, or certain ADAS applications. The field of view (FOV) specifications listed in Table 2 consider the coverage of a wide range of distances. Some believe narrower FOVs can be tolerated if the LiDAR is used for long range only while some insist a full 360\({}^{\circ}\) horizontal coverage. The 0.1\({}^{\circ}\) angular resolution results from the requirement of resolving a human body size at 200 m. The 15 Hz frame rate is an average of required frame rate range to track moving objects in certain road conditions [14]. The industry is at its very early stage of developing and deploying LiDAR in  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Items** & **Specs** & **Conditions** \\ \hline Range & \textgreater{}200 m & 10\% reflectivity \\ Horizontal FOV & \textgreater{}120\({}^{\circ}\) & / \\ Vertical FOV & \textgreater{}25\({}^{\circ}\) & / \\ Angular resolution & \textless{}0.1\({}^{\circ}\) & / \\ Frame rate & \textgreater{}15 Hz & / \\ \hline \hline \end{tabular}
\end{table}
Table 2: Estimated specifications of LiDAR for Level 4 and 5 autonomous vehicles.  
automotive and is far from reaching agreement on these specifications. Nevertheless, we use the values in Table 2 as a general guideline in following discussions.
## 3 Results and Discussion
### Discussion: Reasons for Variability in Macro Anisotropic Parameters
Therefore, an electromagnetic monitoring system should aim to track all elements of the macroscale anisotropy tensor of electric conductivity. Choosing an observation system for electromagnetic monitoring involves analyzing various systems to determine the most sensitive and informative approach for all elements of the macroscale anisotropy tensor of electric conductivity. This necessitates solving forward and inverse problems in inhomogeneous anisotropic media. Our findings validate the concept that continuous electromagnetic monitoring can aid in identifying natural disasters such as earthquakes based on variations in integral macroscopic parameters.
## 5 Experimental Results
### BATMAN IV with Split Hop Penalty
Figure 10: Average roundtrip time for (**a**) original hop penalty and (**b**) split hop penalty. Jitter, a measure of variance in the delay, is an important factor for real-time applications, where updated information has a higher priority as compared to the number of packets lost during the mission-critical transmission. Figure 12 presents the comparisons of jitter for (a) the original hop penalty and (b) the split hop penalty. The experimental data are shown in Table A4. The differences can be spotted at several points in Figure 13. The most prominent is the axis which shows that the overall jitter for the newly proposed scheme is much less than the original hop penalty. The less jitter will contribute to much more reliable communication, less re-transmission, and smaller delays. The most prominent measure of jitter 243 ms was recorded with the highest number of nodes of 14, while it is only 156 ms with the same number of nodes in split hop penalty. Similarly, the smallest average calculated with the original hop penalty is 9.95 ms as compared to 5.64 ms for the split hop penalty. The data recorded at 0 dBm are mostly distinguished as compared to other transmit power. Still, the split hop penalty not only performs better but is also comparable to other transmit powers in the range of 2 to 6 nodes, while increasing rapidly as the number of nodes increases.