esa-sceva/satcom-chunk-collection huggingface dataset:
## 2 Theory of TRM-SBDC UWA Communication
### Principles of Single Element TRM  
The multipath spreads of UWA channels cause severe ISI, thereby degrading the quality of the communication signals, so it is necessary to perform channel equalization processing on the received signals. In this paper, the TRM based on a single sound pressure sensor is used to process the received signals. Although the single element TRM loses the spatial focusing gain of the vertical array, it can still undo the multipath or channel distortion and suppress ISI. Figure 3 illustrates the block diagram of single element TRM.  
When performing time reversal communication, the transmitter usually sends a probe pulse signal to estimate the channel impulse response (CIR). The sync signal is used instead of the probe pulse signal in the paper, which is beneficial to save communication time and improve communication efficiency. The signal \(s(t)\) transmitted by the transmitter, including the sync signal \(p(t)\) and the information signal, passes through the UWA channel and is then received by the single sound pressure sensor. Assuming that the channel is stationary during the signal propagation, so the received signal can be expressed as:  
\[p_{\tau}(t)=p(t)*h(t)+n_{p}(t) \tag{1}\]  
\[s_{\tau}(t)=s(t)*h(t)+n_{s}(t) \tag{2}\]  
where \(h(t)\) is CIR, \(n_{p}(t)\) and \(n_{s}(t)\) are underwater noises, and \"\(*\)\" denotes convolution. Due to the multipath spreads, the CIR can be expressed as:  
\[h(t)=\sum_{i=1}^{N}A_{i}\delta(t-\tau_{i}) \tag{3}\]  
where \(N\) is the number of multipath between the transmitter and receiver, and \(A_{i}\) and \(\tau_{i}\) are the amplitude and time delay of the \(i\)th path.  
Figure 3: The block diagram of single element TRM.  
Figure 2: The symbol structure of PDS scheme.  
The sync signal is intercepted from the received signal and processed by copy-correlation technique. Then the CIR estimation denoted as \(h^{\prime}(t)\) is output. Finally, the received signal is convoluted with the time-reversed channel \(h^{\prime}(-t)\) to obtain the final signal \(r(t)\), which can be expressed as:  
\[\begin{array}{ll}r(t)&=s_{r}(t)*h^{\prime}(-t)\\ &=s(t)*h(t)*h^{\prime}(-t)+n_{s}(t)*h^{\prime}(-t)\\ &=s(t)*\hat{h}(t)+n(t)\end{array} \tag{4}\]  
where \(\hat{h}(t)=h(t)*h^{\prime}(-t)\) denotes the virtual UWA channel through which the signal ultimately passes, and \(n(t)=n_{s}(t)*h^{\prime}(-t)\) denotes the noise component. From a signal processing point of view, the virtual UWA channel is a cross-correlation function between the actual CIR and the estimated CIR. When the estimated CIR and the actual CIR match well, the energy of multipath signal is superimposed and the temporal focusing is achieved. In an ideal case, the virtual UWA channel approaches a delta function with a strong correlation peak and some low side lobes. That is to say, the single element TRM compresses the multipath structure, so that the virtual UWA channel can be viewed as a single path channel, thus the ISI is suppressed.
# An Improved Reference Paper Collection System Using Web Scraping with Three Enhancements
## 9 Evaluation and Analysis
### System Performance Metrics Comparison
#### 9.2.2 Response Time  
The response time of a system is a critical metric because users expect timely feedback to their queries. We compared the proposed system with our previous work in the response time. Although utilizing multiple APIs, the proposed system demonstrates its efficiency by implementing multi-threading using _ThreadPoolExecutor_[51] for retrieving articles simultaneously, compared to our previous work. The evaluation of the system performance in response time is illustrated in Figure 14.  
Figure 14 shows that the response time of the proposed system takes 35.03 s on average, while our previous work takes 87.10 s. It indicates that the proposal responds to user queries more twice as fast. The fastest response time is observed in _Case 1_ and _Case 3_, where the proposed system requires 33.64 s and 17.7 s, respectively, to retrieve articles related to \"Web Scraping using Selenium\" and \"Healthcare Chatbot Natural Language Processing\". It aligns with the small number of available reference papers obtained. In contrast, the proposed system requires a slightly higher response time, where 41.29 s in _Case 2_ and 33.8 s in _Case 4_, respectively. It corresponds to the increased the number of available references retrieved, 99 articles in _Case 2_ and 85 articles in _Case 4_.  
The highest response time occurs in _Case 5_, which requires 48.74 s, corresponding with the second highest number of available reference papers, retrieved up to 87 articles. In contrast, our previous work requires 186.09 s to retrieve a small number of relevant accessible PDFs. We observed an incremental increase in response time load in our previous work when testing all cases.  
To measure the efficiency of the response time reduction, we calculated the percentage decrease by the following Equation (3) [56]:  
\[\Delta y=\frac{(y_{1}-y_{2})}{y_{1}}\times 100\% \tag{3}\]  
Figure 14: Comparison of response time.  
We assumed that \(y_{1}\) represents the response time for our previous work, \(y_{2}\) does the response time for the proposed system, and \(\Delta y\) does the percentage reduction in the response time. The proposal reduces the response time by 59.78% on average, compared to our previous work. It indicates that the proposal achieved good performance using multi-threading with Python _ThreadPoolExecutor_ in reducing the response time.
## 3 Results of Experiments and Their Discussion
### EBSD Observations
(**a**) \(\varepsilon=2.5\%\) (**b**) \(\varepsilon=15\%\), (**c**) \(\varepsilon=30\%\), and (**d**) \(\varepsilon=40\%\) samples. Figure 5: (**a**) Grain size distribution and (**b**) evolution of average grain size as a function of \(\varepsilon\). A significant increase in matrix deformation with increasing strain can also be revealed by point-to-point misorientation analysis. Figure 7a shows the evolution of boundaries representing intergranular strain (misorientation 2-5\({}^{\circ}\)), low-angle grain boundaries (LAGBs, misorientation 5-15\({}^{\circ}\)), and HAGBs (misorientation \(>\) 15\({}^{\circ}\)). Figure 7b shows the normalised distribution of misorientation in the range of 0-5\({}^{\circ}\). The HAGBs length fraction was initially relatively high and started to rapidly decrease only after the deformation exceeded 10%. At the same time, a rapid increase in boundaries representing intergranular strain (2-5\({}^{\circ}\)) occurred. On the other hand, the evolution of LAGBs was initially unaffected and gradually increased only for \(\varepsilon>\) 15%. The distribution of misorientations representing intergranular strain shown in Figure 7b is consistent with the KAM analysis and presents some degree of quantification of data shown in Figure 6. An increase in strain caused a significant broadening of the distribution and its shift towards the higher values of misorientation. A substantial change in the distribution shape occurred when the strain exceeded 10%, which corresponds with the rapid increase in the 2-5\({}^{\circ}\) boundaries length fraction, depicted in Figure 7a. Note that the distributions in Figure 7b are normalised and, therefore, a change in their height does not reflect the change in the overall fraction of misorientations  
Figure 6: Kernel average misorientation (KAM) maps calculated from EBSD data. (**a**) \(\varepsilon\) = 2.5%, (**b**) \(\varepsilon\) = 15%, (**c**) \(\varepsilon\) = 30%, and (**d**) \(\varepsilon\) = 40% samples. \(<5^{\circ}\), with respect to all points. However, this can be estimated when the data shown in Figure 7a are considered.
## 3 Finite Element Analyses
### Slot Opening Width Analysis
#### 3.2.2 Trapezoidal Slot  
The same slot-opening analysis was carried out for the trapezoidal shape and the FEA results lead to discordant results. A narrow slot opening, as in Figure 11, guarantees significantly lower total power losses and a smaller percentage difference between impedance, \(\Delta Z\%\). More specifically, the total power losses percentage reduction corresponds to 15.64% if the narrowest slot-opening is chosen rather than the widest one, see Figure 12, and \(\Delta Z\%\) equals 56.49% instead of 85.16%, see Figure 13.  
Figure 11: Trapezoidal slot with the narrowest (**a**) and the widest slot opening (**b**).  
Figure 10: Rectangular slot–impedance comparison.  
This inconsistency implies that another design parameter, that makes the slot-opening width significant, could exist: the teeth width \(w_{t}\). In fact, if the teeth are too wide, the ferromagnetic material does not reach the saturation state and the magnetic flux paths are not efficiently employed.
# Real-Time Implementation of Multiband Spectrum Sensing Using SDR Technology
## 1 Introduction
The authors in [26] presented a CR system in a real environment in which nodes can either communicate with other nodes via (i) a direct communication with the base station at the macrocell, which helps to enhance network performance, or (ii) device to device that improves spectrum efficiency, whereby traffic is offloaded from macrocell to small cells, using two USRP platforms combined with the GNU radio software toolkit. In [27], the authors used USRP with Raspberry to develop a distributed wireless network in which nodes can communicate with other nodes independently and these can take decisions autonomously. In [28], a small-scale testbed was proposed for dynamic spectrum access in a CR network to find a common channel for communication between two devices (peer to peer, using USRP). A technique for dynamic spectrum access was also presented. In [29], a didactic spectrum analyzer application with multiple functions was presented that uses an SDR device at a very low cost. Many important contributions related to CR have been implemented considering USRP devices. Nevertheless, in this work, the main motivation consists of showing that SDR devices can be useful for providing information about how a theoretical contribution could behave implemented in real time without a considerable investment compared to the high economic cost that could represent USRP devices [30; 31]. This work is organized as follows: in Section 2 a brief description of the considered SDR devices is presented. In Section 3, the implementation of the MBSS technique using SDR technology is explained. Section 4 presents the implemented scenario and results. Section 5 provides the conclusion and a brief discussion.
## 2 Materials and Methods
### Analysis of the Antioxidant Activities  
The 1,1-diphenyl-2-picrylhydrazyl (DPPH) free-radical scavenging activity of each extract obtained from leaves or roots of five genotypes was measured using DPPH free radicals, as described by [PERSON] et al. [6]. With various concentrations (62.5, 125, 250, 500, and 1000 ug/mL) of each test sample, 90 uL of 0.4 mM DPPH solution was mixed. After incubation for 10 min at room temperature, the absorbance was measured at 520 nm using a spectrophotometer. The findings were presented as the concentration necessary to neutralize 50% of the initial DPPH free radicals (IC50).  
Reducing power was measured by monitoring the ability of the extract to reduce Fe3+ to Fe2+ at 750 nm, as described by [PERSON] et al. [6], with ascorbic acid (AsA) as a positive control. Briefly, each extract (200 ug/mL) was mixed with 0.2 mL of 200 mM sodium phosphate buffer (pH 6.6) and 0.2 mL of 1% potassium ferricyanide. After incubation at 50 \({}^{\circ}\)C for 20 min, the mixture was mixed with 1 mL of 10% trichloroacetic acid and centrifuged at 6500 rpm for 10 min. Then, 500 uL of aliquots of the supernatants were mixed with 500 uL of deionized water and 100 uL of 0.1% ferric chloride, and the absorbance was measured at 750 nm.  
The oxygen radical antioxidant capacity (ORAC) assay was conducted as previously described [6], using Trolox as a standard. A total of 150 uL of 0.08 uM fluorescein, diluted in a phosphate buffer (75 mM, pH 7.0), was mixed with 25 uL of phosphate buffer (used as a blank), Trolox standard (ranging from 6.25 to 50 uM), or each extract (40 ug/mL), with each placed in separate wells of a microplate. Following incubation at 37 \({}^{\circ}\)C for 10 min in the dark, 25 uL of freshly prepared 2,2\({}^{\prime}\)-azobis(isobutyrimidine) dihydro solution (0.12 g/mL) was added. Fluorescence intensity was monitored with fluorescent filters (485 and 530 nm excitation and emission wavelengths, respectively). ORAC values were represented as uM Trolox equivalent concentration (uM TE).
## 2 Fabrication and Setup
### Fiber Bragg Grating Inscription  
The inscription of FBGs on the MgO-NP fiber has been carried out by means of a fs laser and phase mask method [10; 11][20], using the setup sketched in Figure 1a. The optical fiber has been placed between two fiber holders, leaving the stripped MgO-NP fiber section exposed to the phase mask area. With this setup, two FBGs have been inscribed, at 3 cm distance from each other. The first FBG has 2 mm length, and Bragg wavelength of 1538.5 nm (phase mask with a pitch of 1061 nm) at room temperature; the second FBG has 4 mm length, and Bragg wavelength around 1552.2 nm (phase mask with a pitch of 1072 nm) at room temperature. The spectrum of the second FBG, the one used in the spectral and polarization analysis, is reported in Figure 1b.
# FarpScun: Fully Anonymous Routing Protocol with Self-Healing Capability in Unstable Sensor Networks
## 3 Fully Anonymous Routing Protocol with Self-Healing Capability
### Performance Analysis  
#### 3.5.1 Anonymity  
The proposed protocol realizes three kinds of anonymity: source nodes, destination nodes and communication association anonymity. In this section, we will analyze the anonymity performance of the proposed protocol under active attacks. It is assumed that the active attackers can compromise some nodes of a given network and, thus, extract data from these nodes. However, an attacker cannot discover the communication association between the base station, source node, and other nodes in a given network. The detailed analysis is as follows.  
(1) Source nodes anonymity  
It is assumed that the active attacker can crack some nodes of a given network and expose data. However, the attacker cannot find the source node. We show the following:  
Suppose that the source node \(S\) passes the underlying data to node \(N\),  
\[E_{pk_{N}}(SessID)||HIA_{ID,S\leftrightarrow N}||E_{K_{S}\leftrightarrow N}( pk_{G})||E(S,pk_{G})||E\left(z_{S},pk_{G}\right).\]  
This transport hides the source node ID and the address information in \(HIA_{ID,S\leftrightarrow N}\) and \(E(S,pk_{G})\). Assuming this transmission does not encounter a damaged node before reaching the base station, the attacker cannot find the information of the source node based on the intercepted information.  
(2) Communications association anonymity  
When the node \(i\) communicates with the node \(j\), the shared key of nodes \(i\) and \(j\) cannot be obtained for the third party node. Therefore, it is not possible to calculate \(HIA_{ID,i\leftrightarrow j}=H_{1}\left(Key_{i,j}\oplus ID_{i}\oplus ID_{j}\right)\), the attack node cannot impersonate the node to communicate, and can not know which two nodes to communicate, which ensures the anonymity of the communication association.  
(3) Destination nodes anonymity  
During data transmission, the packet does not contain any information regarding the base station. For passive attackers, it is difficult to find base station nodes from the captured packets. Moreover, the active attacker cannot find the communication association between two nodes as described above, so it is difficult to find the base station, even the active attacker.  
In Table 3, we give detailed analysis of anonymity in the proposed protocol and the existing protocols. We infer from Table 3 that \(APR\) only implements communication association anonymity, \(RandomWalk\) only implements destination nodes anonymity [21; 22]. However, our proposed protocol \(FarpScusn\) has achieved all three types of anonymity simultaneously.  
The improved scheme accomplishes that the adversary cannot determine the identity of the sender and receiver by extracting the messages that are intercepted from the network or by extracting the messages forwarded by its leaking sensor node. The adversary cannot determine whether or not two communication segments (message transmission between two adjacent nodes) belong to the same communication between the source and destination nodes [23].
## 3 Results and Discussions
### Influence of Crumb Rubber on Pervious Concrete Properties
#### 3.1.5 Freeze-Thaw Resistance  
The compressive strength loss ratio of CPC and RMPC under freeze-thaw cycles is shown in Figure 11. It can be clearly seen that the compressive strength loss ratios for all mixtures increased with the increasing freeze-thaw cycles. This is because the bonding between the aggregate and cement paste is weakened due to the freeze-thaw cycles. On the other hand, the pore water in the specimen freezes and expands when the specimen suffers freezing, which results in cracks in the concrete. All of these changes are expressed at the macro level as a reduction in compressive strength. The weakening effect of the freeze-thaw cycles on the compressive strength is more and more obvious as the freeze-thaw cycles increase. It is obvious that the strength loss is smaller when the freeze-thaw cycle is lower.  
Furthermore, the content of rubber has a significant effect on the freeze-thaw resistance of pervious concrete. The improvement of the freeze-thaw resistance is obvious as rubber content increases. RMPC has lower strength loss ratios at each freeze-thaw level compared to CPC. The reason is that the addition of rubber reduces the stiffness of concrete and makes concrete a flexible material. Based on this fact, RMPC could better release frozen-heave force and reduce the damage caused by freezing, thus enhancing freeze-thaw resistance.  
The test results indicate that rubber particles also have an important effect on freeze-thaw resistance. FCR-modified mixtures present better freeze-thaw resistance compared to CCR-modified mixture at the same level of freeze-thaw cycle, which indicates that smaller rubber particles are more advantageous for freeze-thaw resistance. This is because FCR makes the distribution of frozen-heave  
Figure 10: Load-displacement curves of fine crumb rubber (FCR)-modified mixtures.  
Figure 9: Flexural strain of RMPC versus rubber content.  
force more uniform, which avoids stress concentration and results in a lower frozen-heave force in FCR-modified mixtures.
## 3 Application of the TGF_N_V for Solving Roll Damping of Hull Sections with Bilge Keels  
A novel body-nonlinear Green's function method with viscous dissipation effects (TGF_N_V) was developed in Section 2. In this section, TGF_N_V is employed to solve the roll damping of hull sections with bilge keels under small and large roll amplitude. For comparison purpose, numerical results from linear inviscid time-domain Green's function method (TGF) [25], body-nonlinear inviscid time-domain Green's function method (TGF_N) [25], and experimental fluid dynamic (EFD) results [13] are also provided in the cases.
# Threat Analysis and Risk Assessment (TARA) Analysis of an Autonomous Emergency Braking (AEB) System
## 4 Feature Description
### Trust and Security Considerations  
* **Cluster Trusted Boundary**: The diagram highlights a trusted boundary around the cluster, indicating that certain communications or data flows are secured or trusted within this area. This boundary is crucial for maintaining the integrity and security of the AEB system, ensuring that data within this cluster are protected from tampering or unauthorized access.
* **Hardwire Connection**: this connection suggests an external or possibly less secure communication link, marked with a dotted red line, indicating the need for heightened security measures or monitoring.
## 5 Analysis on Bearing Capacity of PHC Modular Pile
### Effect of Nodular Spacing  
The nodular spacing of the PHC nodular pile S was set as 1 m, 1.8 m, 2.6 m, 3.4 m and 4.2 m, respectively, in the modeling, and the calculated load-displacement responses of PHC nodular pile with different nodular spacing were arranged as shown in Figure 7. It can be seen in Figure 7 that the bearing capacity of the 450 (500) mm PHC nodular pile with a nodular spacing of 1 m and 1.8 m was better than the bearing capacity of 500 mm PHC pipe pile. When the pile head displacement reached 40 mm, the ultimate bearing capacity of the 450 (500) mm PHC nodular pile with a nodular spacing of 1 m and 1.8 m were 2357 kN and 2109 kN, respectively, which were larger than the ultimate bearing capacity of 500 mm PHC pipe pile. Nevertheless, when the nodular spacing increased to 2.6 m, the ultimate bearing capacity of the 450 (500) mm PHC nodular pile decreased to 1843 kN, which was smaller than the ultimate bearing capacity of the 500 mm PHC pipe pile. When the nodular spacing increased to 3.4 m and 4.2 m, the ultimate capacity decreased to 1688 kN and 1678 kN, respectively, which was close to the ultimate bearing capacity of the 450 mm PHC pipe pile.  
According to the analysis above, the bearing capacity of the PHC nodular pile would decrease with nodular spacing. When the nodular spacing was 1.0 m and 1.8 m, the ultimate bearing capacities of the 450 (500) mm PHC nodular pile were 1.18 and 1.05 times that of the 500 mm PHC pipe pile. When the nodular spacing increased to 2.6 m, the ultimate bearing capacity of the 450 (500) mm PHC nodular pile was 0.92 times of the ultimate bearing capacity of the 500 mm PHC pipe pile, while ultimate bearing capacity of the 450 (500) mm PHC nodular pile was 1.1 times of the ultimate bearing capacity of the 450 mm PHC pipe pile. Hence, the nodules could still increase the bearing capacity of the pile when the nodular spacing reached 2.6 m. It should be noted that when the nodular spacing increased to 3.4 m and 4.2 m, the ultimate capacity of the 450 (500) mm PHC nodular pile was close to the ultimate capacity of the 450 mm PHC pipe pile, which indicated that the nodules could not improve the pile capacity. For the design of the PHC nodular pile in  
Figure 7: Effect of nodular spacing on bearing capacity of PHC nodular pile.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Item** & \multicolumn{4}{c}{**Parameter Values**} \\ \hline Nodular spacing & 1 m & 1.8 m & 2.6 m & 3.4 m & 4.2 m \\ Nodular length & 25 mm & 75 mm & 125 mm & 175 mm & 225 mm \\ Nodular diameter & 500 mm & 525 mm & 550 mm & 575 mm & 600 mm \\ Nodular angle & 0\({}^{\circ}\) & 26.6\({}^{\circ}\) & 45\({}^{\circ}\) & 56.3\({}^{\circ}\) & 63.4\({}^{\circ}\) \\ \hline \hline \end{tabular}
\end{table}
Table 3: Nodule parameters in ABAQUS modeling.  
engineering projects, the nodular spacing should be smaller than 1.8 m to fully mobilize the bearing capacity of the PHC nodular pile.