esa-sceva/satcom-chunk-collection huggingface dataset:
# Effect of Formation Size on Flocking Formation Performance for the Goal Reach Problem
## 2 Materials and Methods
### Computing the Final Desired Direction  
After calculating each vector's desired direction, each agent must have a single direction (\(d_{i}\)) to move towards. The final desired direction is determined according to the sensed positions of neighboring agents and the current environment status (goal and obstacles).  
In the case that neighbors are detected in the repulsion zone, the final desired direction is computed according to Equation (1) [14]. For example, Equation (1a) indicates that, in the case that obstacles are detected in addition to the goal zone, then the function computing \(d_{i}\) will guide the agent away from neighbors (\(\hat{dr}_{i}\)) and obstacles (\(\hat{db}_{i}\)), but also towards the goal (\(\hat{dg}_{i}\)). Note that the exploration capability (\(\hat{de_{i}}\)) is only activated in the absence of goal detection (Equations (1c,d)). [PERSON] et al. [14] have used three weights, \(w_{1}\), \(w_{2}\), and \(w_{3}\), such that avoiding collisions between neighbors was assigned higher priority than that of alignment and cohesion. The sensing power feature and conditions (Equation (1e)) are explained in Section 2.5.  
\[d_{i}=\left\{\begin{array}{ll}w_{1}\hat{dr}_{i}+w_{2}\hat{db}_{i}+w_{3}\hat {dg}_{i},&\text{goal zone and obstacle detected}&(a)\\ w_{1}\hat{dr}_{i}+(w_{2}+w_{3})\hat{dg}_{i},&\text{goal zone detected}&(b)\\ w_{1}\hat{dr}_{i}+w_{2}\hat{db}_{i}+w_{3}\hat{de}_{i},&\text{obstacle detected}&(c)\\ w_{1}\hat{dr}_{i}+(w_{2}+w_{3})\hat{de}_{i},&\text{agents detected in }zor.&(d)\\ s\hat{p}_{i},&\text{conditions for sensing power satisfied}&(e)\end{array}\right. \tag{1}\]  
If no neighbors are detected in the repulsion zone, then the final desired direction will be computed according to Equation (2). Note that the alignment and orientation capabilities are used only in the absence of neighbors in the repulsion zone [13].  
\[d_{i}=\left\{\begin{array}{ll}\hat{d}_{i}+\hat{da}_{i}+\hat{db}_{i}+\hat{dg }_{i},&\text{goal zone and obstacle detected}&(a)\\ \hat{d}_{i}+\hat{da}_{i}+\hat{db}_{i}+\hat{de}_{i},&\text{goal zone detected}&(b)\\ \hat{d}_{i}+\hat{da}_{i}+\hat{db}_{i}+\hat{de}_{i},&\text{obstacle detected}&(c)\\ \hat{d}_{i}+\hat{da}_{i}+\hat{de}_{i},&\text{other agents detected in perception zone}&(d)\\ s\hat{p}_{i},&\text{conditions for sensing power satisfied}&(e)\end{array}\right. \tag{2}\]
# Recognizing Urban Functional Zones by GF-7 Satellite Stereo Imagery and POI Data
## 3 Methodology
### Multimodal Data Feature Extraction and Fusion
#### 3.3.2 Semantic Feature Extraction  
POI data provide valuable insights into human economic activities. However, some previous studies have primarily focused on counting POI frequencies for text modeling, ignoring the potential semantic features [52; 53; 54]. LDA [55] is a three-layer Bayesian probability model, which can identify the semantic topic information in large-scale document sets or corpus. It has demonstrated promising results in identifying UFZs [56; 57]. The number of topics is crucial for LDA. An appropriate number of topics can effectively prevent overfitting and obtain higher accurate results. We use the confusion algorithm to calculate the number of topics, and the smaller the perplexity, the more appropriate the determined number of topics is for LDA [55]. We utilize the secondary classification of Gaode POI to divide the functional categories of each POI data, the POI functional attributes within the same functional unit are regarded as a document in the LDA model. Figure 8 shows the perplexity values for 1 to 99 topics. When the topic number is 25, the perplexity is the  
Figure 7: Multimodal data fusion model.  
smallest. Combined with the UFZs category, the number of topics is finally determined to be 22 for LDA modeling; 14 topics correspond to a commercial zone, 4 topics correspond to public service, 2 topics correspond to a residential zone, 1 topic corresponds to education, and 1 topic corresponds to green land. Due to the proportion of corresponding topics in different urban functional units is not balanced, the semantic shrinkage method proposed by [PERSON] et al. [58] is adopted to process the probability values of different types of topics in the same urban functional unit. Finally, each urban functional unit corresponds to the probability of five kinds of urban functions, both residential zone and shantytowns undertake residential functions and are combined into one topic. There are almost no POIs in development, and the topic of development is discarded.
# Algebraic Point Projection for Immersed Boundary Analysis on Low Degree NURBS Curves and Surfaces
## 4 Methodology of Algebraic Point Projection  
In this section, we describe the developed procedure for algebraic point projection. The development of the algorithmic procedure is initially motivated using one-parameter NURBS curves and later extended to two-parameter NURBS surfaces.
# Numerical Evaluation of Rotordynamic Coefficients for Compliant Foil Gas Seal
## 3 Results  
### Numerical Analysis for Reliability  
Ma [14] developed FEM to analyze the performance of the spiral cylinder gas seal based on the Reynolds lubrication theory. The pressure distribution of the gas seal is obtained for testing case validation in this paper, and the comparison of pressured results is shown in Figure 2. The number of nodes and elements for FDM this research used is based on [PERSON]'s paper, which is approximately 16,000. The inlet pressure is 301,325 MPa, and the speed is 10,000 rpm. The operation condition adjusts according to the boundary condition [19]. This paper used the central difference method of FDM to solve the pressure distribution rotordynamic coefficients. Figure 2a shows the non-dimensional film thickness of the gas film. Figure 2b,c illustrates the results of the circumferential direction pressure distribution with five different non-dimensional length positions at the T-shaped groove area and smoothing area of the seal (axial direction \(\overline{z}\approx\) 0.21, 0.42, 0.53, 0.64, and 0.85). As the approximate \(\Lambda\) = 27, the position \(\overline{z}\approx\) 1 is far from the groove area, which is similar to the smoothing structure of Cheng [9], and the pressure distribution of the other areas is almost the same. Therefore, the results were validated. However, Figure 2c shows that the pressure of \(\overline{z}\approx\) 0.21, 0.42, and 0.53 decreases abruptly in the near thinnest position, which results from the impact of the groove on the pressure. Furthermore, Figure 2 also shows that the peak pressure is clearly higher than the smoothing area due to the influence of the T-shaped groove. The rise of pressure is beneficial to improve the rotordynamic coefficients.
## 5 Communication Dependability
### Cybersecurity for IEC61850 Multicast Communication in Wide-Area Applications
#### 5.2.2 Secured Communication Path
In phase 1, both IPsec peers (FHR and LHR) are authenticated by exchanging security credentials (e.g., pre-shared key of certificates). After successful authentication, the IPsec peers negotiate a common security association that identifies the security algorithms and policies to be used for encrypting and authenticating the communication. In phase 2, the Diff  
Figure 15: Secured messages in the secured communication path (Defense-in-Depth Security for multicast communication via public WAN). method is used to generate a shared key used for securing the WAN communication by ESP: encrypting IP packet and adding authentication data (ESP Auth). Thus, a secured communication path is created for R-SV/R-GOOSE messages as depicted in Figure 15. In the following, Figure 16 shows the structure of the messages transmitted between FHR and each LHR after successful IKE authentication. It should be noted that Figure 16 shows how non-secured R-SV/R-GOOSE messages can be secured for public WAN communication by ESP. However, Figure 15 depicts the Defense-in-Depth security scenario (secured R-SV/R-GOOSE messages over secured communication path) which highlights the security measures at different levels: end-to-end security by IED's TEK as well as point-to-point security by ESP. In Figure 15, the IP-Multicast sender contacts KDC and receives IED's TEK (AK, EK, or both) to create secured R-SV/R-GOOSE messages. These messages are then sent to the FHR where a GRE tunnel endpoint (head-end) encapsulates them. The FHR then encrypts these encapsulated messages by ESP. The LHRs receive the encrypted messages, and, after the ESP decrypts them, the GRE tunnel endpoints (tail-ends) decapsulate the messages. After decapsulation, the received secured R-SV/R-GOOSE messages are forwarded to the IP-Multicast receivers, which have already received the IED's TEK from KDC and can use it for decrypting/verifying secured SV/R-GOOSE messages. As can be seen in Figure 16, the final packet (transmitted between FHR and LHR) contains six IP addresses. The IP Header contains IP addresses of the IP-Multicast sender (IED) as well as the multicast destination IP address. The Delivery Header contains the GRE tunnel endpoint (head-end and tail end) IP addresses in the edge routers. The New IP Header includes public IP addresses of the IPsec peers (FHR and LHR). It is obvious from this that the security solutions use additional communication headers which inevitably increase processing times. These additional delays to R-SV/R-GOOSE communication may affect the real-time requirements of wide-area applications, so any security solutions must be designed with respect to the application real-time constraint.
# An On-Demand Scheduling-Based MAC Protocol for UW-WiFi Networks
## 1 Introduction
To avoid collisions of request packets during the reservation phase, the sending time of request packets from each terminal node is calculated by exploiting propagation delays. During the time sequence scheduling phase, the timing of every node beginning to transmit data is figured out according to the data transmission delay and the propagation delay from itself to the master node. This on-demand scheduling algorithm does not require time synchronization and saves energy by reducing the number of control packets and preventing all packets from conflicting. Overall, the key contributions of our work are summarized as follows:  
* Based on the UW-WiFi network scenario that addresses real-world application issues, and taking the above various constraints into account, a practical MAC protocol is proposed, which can allocate channel resources on demand according to the different data sizes of each node under diverse duties. * To thoroughly verify the practicability of the SDDA MAC protocol, we have performed numerous simulations and two types of ocean trials. The comparison simulation experimental results show that the SDDA protocol substantially outperforms TDMA and S-FAMA [6] on channel utilization, packet delivery ratio, and end-to-end delay. Then, we implement the SDDA protocol in the embedded motherboard and build a real UW-WiFi network system at Daya bay, Shenzhen. The first type of tests is mainly to validate the effectiveness of the simulation, and it is obtained that the sea test results conform to the simulation. The other type is the experiments on different tasks of nodes, from which we collect the distinct real ocean data, which demonstrate the utility of the proposed protocol. The sea trials also show that the SDDA is a feasible solution for the real UW-WiFi network deployments. The remainder of this paper is organized as following. Section 2 gives a brief overview of the state of art on the related protocols. Section 3 discusses the application scenario. Section 4 gives a detailed description of the proposed SDDA MAC protocol. Section 5 presents extensive simulations and sea trials to testify the performance of the SDDA protocol. Finally, Section 6 concludes the paper.
## 2 Structure of Hybrid AC/DC Microgrid
### AC Coupled Hybrid Microgrid  
In AC coupled microgrid, as shown in Figure 1, distributed generators, energy storage systems, and utility are connected to the main AC bus. The connection of the energy storage system and DC loads is done through bidirectional interfacing converters. It is the most frequently used topology worldwide due to its simplicity and availability of AC generation systems. However, interfacing converters account for the existing inefficiency in this topology.
# Entropy-Regularized Federated Optimization for Non-IID Data
## Appendix B Convergence of ERFO Under Non-Convex Objectives
### Convergence to Stationary Points  
Using the assumptions in Appendix B, we extend the convex analysis (Appendix B) to the non-convex case.  
**Theorem A1** (Convergence of ERFO in the Non-Convex Setting).: _Let \(F(w)=\frac{1}{N}\sum_{i=1}^{N}F_{i}(w)\) satisfy the smoothness, bounded-variance, and bounded-drift conditions of Appendix B.1. Run ERFO for \(T\) communication rounds with all \(N\) clients and \(\tau\) local SGD steps per client per round. Then_  
\[\frac{1}{T}\sum_{t=0}^{T-1}\mathbb{E}\big{[}\|\
abla F(w_{t})\|^{2}\big{]} \leq\frac{2\big{(}F(w_{0})-F(w^{*})\big{)}}{\eta\;\tau\;T}+\frac{\eta L\sigma ^{2}}{2}+\mathcal{O}\big{(}\eta\lambda^{2}\big{)},\]  
_where \(F(w^{*})\) is any lower bound of \(F\). With sufficiently small fixed \(\eta\) and \(\lambda\), the right-hand side decays as \(\mathcal{O}(1/T)\); hence \(\min_{0\leq t<T}\mathbb{E}\big{[}\|\
abla F(w_{t})\|^{2}\big{]}\to 0\) as \(T\to\infty\)._  
Proof Sketch.: The argument follows the FedAvg/FedProx template with an extra entropy term.  
**(i) First local step.** For client \(i\) at round \(t\),  
\[\mathbb{E}\big{[}F_{i}(w_{t,1}^{i})\big{]}\leq F_{i}(w_{t})-\eta\Big{(}1- \tfrac{L\eta}{2}\Big{)}\|\
abla F_{i}(w_{t})\|^{2}+\eta^{2}L^{2}\sigma^{2}+ \mathcal{O}\big{(}\eta^{2}\lambda^{2}\big{)}.\] (A3)  
**(ii) Subsequent local steps.** For \(k=1,\ldots,\tau-1\),  
\[\mathbb{E}\big{[}F_{i}(w_{t,k+1}^{i})\big{]}\leq F_{i}(w_{t,k}^{i})-\eta \Big{(}1-2L\eta\Big{)}\|\
abla F_{i}(w_{t,k}^{i})\|^{2}+2\eta^{2}L\sigma^{2}.\] (A4)  
**(iii) Telescoping over \(\tau\) steps** and averaging over clients give  
\[\mathbb{E}\big{[}F(w_{t+1})\big{]}\leq F(w_{t})-\eta\Big{(}1-\tfrac{L\eta}{2} \Big{)}\tau\;\|\
abla F(w_{t})\|^{2}+\eta^{2}L^{2}\sigma^{2}\tau+\mathcal{O} \big{(}\eta^{2}\lambda^{2}\big{)}.\]  
**(iv) Summing over \(t=0,\ldots,T-1\)** and rearranging yields the bound in the theorem.  
The entropy contribution is \(\mathcal{O}(\eta^{2}\lambda^{2})\), dominated by the main descent term for small \(\eta\).
# Flexible Antennas: A Review
## 3 Fabrication Techniques for Flexible Antennas
### Special Fabrication Techniques for Flexible Wearable Antennas
#### 3.5.1 Substrate Integrated Waveguide (SIW) Based Technology  
A relatively new method referred to as Substrate Integrated Waveguide (SIW) is highly desirable to realize future system on substrate (SoS) platforms for developing high-performance mm-wave systems [119]. This structure ensures the confinement of electric fields inside the cavity by the use of shorting via on its sidewalls, backed by the full ground plane. The main advantages of the SIW  
Figure 8: Example of wet etching based antenna structure. (**a**) Transparent and flexible antenna fabrication process: (i) polyimide (PI) substrate cleaning; (ii) masking. (iii) deposition; and (iv) mask removal [116] and (**b**) fabricated indium–zinc–tin oxide (IZTO)/Ag/IZTO (IAI) antenna [116] and (**b**) Cu thin film RFID ultra-high frequency (UHF) antenna on PET using photolithography and sputtering [118].  
based technology are the improvement of the Q-factor of the antenna and improving isolation between the antenna and wearers body. A compact substrate integrated waveguide (SIW) based wearable tri-band (ISM, WiMAX, and Military application) leather antenna, designed for optimal on-body performance was proposed in [120]. By using brass eyelets and a combination of conducting and non-conductive leather materials, a substrate integrated waveguide cavity with a ground plane was realized, and miniaturization achieved by introducing slits. In another study [121], a low-cost SIW based antenna made of pure copper taffeta fabric etched on a woolen felt substrate operating from 2.27 to 3.61 GHz was proposed (Figure 9b).  
The antenna topology is based on a folded cavity with an annular ring as a radiating element with a 73% radiation efficiency. Next, a conductive fabric-based SIW based antenna was fabricated on a woolen substrate for off-body applications in an earlier report [122] (Figure 9a). Antennas fabricated using the SIW method is shown in Figure 9. A novel fleece fabric WLAN antenna for wearable applications such as sportswear and emergency worker outfits was reported previously [123].
## 4 Experiments and Comparisons
### Experimental Comparison
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Algorithm** & **Input** & **Reconstruction** & **Depth** & **Filters** & **Parameters** & **Residual Structure** & **Loss** & **Training Time** \\ \hline SRCNN & LR + bicubic & Direct & 3 & 64 & 57 K & No & L2 & 75 h \\ FSRCNN & LR & Direct & 8 & 56 & 12 K & No & L2 & 46 h \\ VDSR & LR + bicubic & Direct & 20 & 64 & 665 K & Yes & L2 & 4 h \\ MDSR & LR & Direct & 162 & 64 & 8000 K & Yes & Charbonnier & 160 h \\ LapSRN & LR & Progressive & 24 & 64 & 812 K & Yes & Charbonnier & 72 h \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Structural analysis of each super-resolution algorithm. effect on observable evaluation indicators, but also had advantages in subjective evaluation according to the subjective intention scores rated by students on each algorithm.
# A Novel Prefix Cache with Two-Level Bloom Filters in IP Address Lookup
## 3 Bloom Filter-Based Prefix Caching
For the Bloom filter test of \(IP_{2}\), the suffix after the prefix \(p\) is used as the input of the hash functions. Two hash values for \(IP_{2}\), \(h_{1}(\mathbf{001000})=001\) and \(h_{2}(001000)=100\) are obtained, as shown in the figure. Since both BF[1] and BF[4] are 1s, it is determined that there is a child prefix in the FIB which \(IP_{2}\) can match. Now, assume that the destination IP address of the second packet is \(IP_{4}=1001111\). In this case, the same matching result \(p=1^{*}\) is determined as the correct hit result. We obtain two hash values, \(h_{1}(\mathbf{001111})=001\) and \(h_{2}(\mathbf{001111})=111\). Since BF[1] = 1 and BF[7] = 0, there is certainly no child prefix of \(p\) which can be matched with the IP address \(IP_{4}\).
# Influence of Milling Techniques on the Performance of Wheat Straw Ash in Cement Composites
## 4 Conclusions  
In this study, the influence of milling techniques on the pozzolanic activity of wheat straw ash (WSA) was investigated. Two types of WSA were created by milling ash in ball mill and disintegrator mill separately, and a third type of ash was created by milling ash first in ball mill and then in disintegrator mill. The grinding of ash particles redefined the particle size distribution by reducing size and enhancing specific surface area. The crystallinity of silica present in the ashes reduced due to the grinding effect. Finest ash particles were obtained by use of both grinding techniques: disintegrator milling and ball milling. Paste specimens with finer ash particles showed an amplified hydration reaction at the early ages, an enhanced compressive and flexure strength. Similarly the incorporation of finer ash particles expressively reduced the CH content in the paste specimens cured for 28 days. Finer ash particles refined the pore structure of the mortar specimens resulting in an improved microstructure, reduced total porosity and enhanced ultrasonic pulse velocity values. Based on the results of this study, it can be concluded that WSA with an enhanced performance can be obtained by applying a combination of disintegrator and ball milling techniques.  
Conceptualization, A.Q. and A.u.R.; methodology, A.Q.; validation, A.Q. and H.G.K.; formal analysis, A.Q.; investigation, A.Q. data curation, A.Q., A.u.R. and I.K.J.; writing--original draft preparation, A.Q.; writing--review and editing, A.Q. and E.K.; visualization, A.Q.; supervision, H.G.K.; funding acquisition, H.G.K. All authors have read and agreed to the published version of the manuscript.  
This research was funded by Ministry of Education through National Research Foundation of Korea (NRF-2019R11A1A01061805) under Basic Science Research Program.  
The authors declare no conflict of interest.
## 3 Challenges for Designing MAC Protocols in UWSNs
### Variability in Propagation Delays  
As we already know that underwater speed of acoustical signals is 1.5 \(\times\) 10\({}^{3}\) (m/s) and having propagation delay of 5 times more, when compared with the terrestrial radio frequency (RF) communication [53]. This high propagation delay in UWSNs is basically the combination of different factors, i.e., attenuation due to reflection/refraction of the acoustical signals from unpredicted seabed and the surface of water [55]. Temperature also plays an important role in making the propagation delays unpredictable/variable. Composition of the wafer is yet another factor that makes the delay variable. In addition, this variability in the propagation time between the sensor and anchor nodes makes our UWSNs accuracy poor, which directly affects the output that we were expecting to have. For instance localization of a sensor node, or sending some critical data to the anchor node so that it can broadcast that information to the base station [56]. All these factor that are making the propagation delay variable will directly impact on the formulation of MAC agreements [57].
# Design, Implementation, and Analysis of a Block Cipher Based on a Secure Chaotic Generator
## 2 Proposed Chaos-Based Cryptosystem
### Circular Substitution Process Based on the S-Box and Their Inverse Processes  
In the following, we first describe the construction process of the S-box, then we give the equation of the circular substitution process based on this S-box. Recall that the S-box is generally the only component of a cryptosystem that gives rise to a nonlinear mappingbetween inputs and outputs. Its main role is to make the cryptosystem immune against differential and linear cryptanalysis, so the security of the cryptosystem is strongly increased.