esa-sceva/satcom-chunk-collection huggingface dataset:
## 3 Multiband Ambient RF Energy Harvester Using the Proposed Antenna  
### Quadplexer Design  
The quadplexer consisted of four parallel channels made by parallel band-stop filters (BSFs) on top of a 0.8 mm thick Roger 4003C substrate as shown in Figure 10a. The theoretical background was based on the proposed triplexer design in [32]. Note that \(f_{1}=2.6\) GHz\({}_{x}f_{2}=1.8\) GHz\({}_{x}f_{3}=2.1\) GHz, and \(f_{4}=2.45\) GHz. Each one of the two middle  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Ref.**} & \multirow{2}{*}{
\begin{tabular}{c} **Freq. \(f_{0}\)** \\ **(GHz)** \\ \end{tabular} } & \multirow{2}{*}{**BW (\%)**} & \multirow{2}{*}{**3 dB-AR BW (\%)**} & \multirow{2}{*}{**Dim. (\(\lambda_{0}\)\({}^{3}\))**} & \multirow{2}{*}{**Gain (dBi)**} \\ \hline
[23] & 7 & 54.3 & 42.1 & 0.49 \(\times\) 0.49 \(\times\) 0.04 & 11.3 \\
[24] & 5.8 & 48.3 & 12  
channels consisted of three open stubs as BSFs corresponding to three rejected bands. The two outer channels used only two stubs each because their three reject bands were close enough to each other; two BSFs are enough to filter the other band. We bent them into an L-shape to reduce size and placed them in serial to each other. The spacings between the first and third stub were first designed to obtain the maximum transmittance within the allowed bands. To be more explicit, each distance was initially assigned as a quarter wavelength of the allowed frequency. The second stub was placed into the middle.  
A 1-4 power divider connected the four channels. To make the design process easier, the power divider was constructed independently of four channels, with equivalent impedances replacing the four channels. Figure 10b shows the simulated S-parameters of the quadplexer. The efficiency at 1.8, 2.1, 2.45, and 2.6 GHz were 93%, 88%, 90%, and 75% in simulation, respectively. The high frequencies make this quadplexer suitable for multiband energy harvesting.
# A Non-Invasive Fetal QRS Complex Detection Method Based on a Multi-Feature Fusion Neural Network
## 2 Signal Collection and Preprocessing
### Signal Multi-Feature Extraction and Combination
#### 2.5.4 Approximate Entropy and Sample Entropy  
Approximate entropy is an indicator used to measure the complexity and irregularity of a signal with a specific resistance to noise. Higher values of approximate entropy usually reflect the signal's irregularity and complexity. This paper extracts approximate entropy information from the ECG signal. The formula for the signal's approximate entropy is as follows:  
\[A_{p}^{En}(m,r)=\phi^{m}(r)-\phi^{m+1}(r) \tag{4}\]  
where \(A_{p}^{En}(m,r)\) represents approximate entropy, \(m\) represents the length of the subsequence, \(r\) represents the matching threshold, and \(\phi^{m}(r)\) represents the conditional probability given the template length \(m\) and the matching threshold \(r\). The formula is as follows:  
\[\phi^{m}(r)=\frac{1}{N-m+1}{\sum_{i=1}^{N-m+1}\ln C_{i}^{m}(r)} \tag{5}\]  
where \(N\) is the length of the time series, and \(C_{i}^{m}(r)\) represents the ratio of the approximate number of matches to the total number. To achieve better statistical properties and smaller errors, the embedding dimension \(m\) is set to 2, and the similarity tolerance \(r\) is set to \(0.2\times std\).
# Measurement and Analysis of RSS Using Bluetooth Mesh Network for Localization Applications
## 5 Analysis of RSS Measurements Using Bluetooth Mesh Network
### Antenna Radiation Patterns  
The first measurement configuration is designed to observe antenna radiation patterns. In this configuration, two pairs of ESP32 modules are used to take RSS measurements. One pair is equipped with the onboard PCB antennas and the other pair is equipped with the external omnidirectional antennas as shown in Figure 2. In the measurement setup, the transmitter (i.e., beacon node) and receiver (i.e., scanner node) devices are mounted on two separate tripods that are 1 m apart. The transmitter remains stationary throughout measurement. The receiver antenna is installed at position P0 on the panning measurement platform and the platform is rotated to six different angular positions with an angular step of 60\({}^{\circ}\). At each angular position, 20 measurements are collected for each of the three advertising channels. The RSS measurement results are shown in Figures 8 and 9. From the results, we can observe that the onboard PCB antenna demonstrates clear directionality while the external antenna has a good omnidirectional radiation pattern. The strong directionality of the onboard PCB antenna will introduce large errors and uncertainty in RSS measurements so that the external omnidirectional antenna should be used in channel measurements for path loss modeling. Another observation is that the differences in the RSS measurement data among the three advertising channels (i.e., channels 37, 38, and 39) are clearly observable even at 1 m distance, which is partly due to the unequal gains across the frequency spectrum in the device signal chain. The external 6 dBi omnidirectional antenna also provides extra gain as compared to the onboard PCB antenna, which effectively increases the coverage of the BLE transceivers during measurement. If not stated otherwise, the measurement data presented in the rest of this paper are all collected using the external 6 dBi omnidirectional antenna.
## 3 Results and Discussion
### Analysis of EDEM Simulation Results and Wear Mechanism Investigation
By guiding the abrasive particles and changing their direction of motion, the contact behavior altered its form from a sliding to rolling state. Therefore, the wear severity was greatly reduced. Moreover, when the abrasive particles were in contact with the micro-thorn and convex hull coupled structured surfaces, along with the convex hull structure that changes the motion behavior of the particle flow, the guiding and rolling effects were greatly enhanced due to the sharp angle of the micro-thorn structure. The direction of particle movement was further changed by guiding the movement of the abrasive particles to both sides and upwards of the micro-thorn. As a result, abrasive particles that altered from a sliding state to rolling state were substantially increased. Furthermore, the rebound angle of abrasive particles after contact with the sample surface was related to its surface morphology [52; 53]. The guiding and rolling effect resulted from the micro-thorn and convex hull coupled structured surfaces were much better than that of the convex hull surface and smooth surface. After the impact of abrasive particles, the rebound angle and the degree of dispersion of particle flow on Bionic Type 3 were greater than that of Bionic Type 1 and the smooth surface. After the impact on the convex hull structure, part of the particles were rebounded and the rebounded particle flow was formed. The rebounded particle flow was further impacted by the forward incoming particles and then moved backward. In the process of backward movement, they were impacted again by the rebound flow of the previous abrasive particles. In the process of repeated impact, a considerable amount of impact energy was consumed. The repeated impact of abrasive particle flow at different levels could buffer the impact kinetic energy of the incoming frontal impact particles; therefore, the impact and cutting force of the abrasive in contact with the Bionic Type 3 surface were greatly reduced. Therefore, the wear resistance performance of Bionic Type 3 was greatly enhanced.
# Mapping [PERSON] Using Sentinel-1 SAR Time Series in Camargue, France
## 3 Methodology
### Decision Tree Classification  
To classify rice crops, a decision tree based on four extracted metrics was built. The rules of the decision tree were determined from the distribution of the values of metrics for all crop types (Figure 7). The results show that a plot with rice cultivation can be identified using the following rules:  
\[Rice=\left\{\begin{array}{l}140\ \leq b\ \leq 210\\ \mathrm{R}^{2}\geq 0.5\\ \mathrm{Variance}\left(\frac{\mathrm{VV}}{\mathrm{VH}}\right)\geq 2.5\\ S>0.01\end{array}\right. \tag{5}\]  
The values of b and \(R^{2}\) are related to the Gaussian fitting of VV/VH because the temporal series of VV/VH follows a Gaussian function for rice, thus the fitting values of b and \(R^{2}\) are within the proposed thresholds. The \(R^{2}\) of the Gaussian fitting was higher than 0.5 for rice and lower than 0.5 for all other crop types. The condition on \(S\) represents the increasing linear profile of the rice cultivation in VH polarization. A lower limit value of 0.01 for \(S\) was proposed to describe this increasing linear profile. In addition, a lower limit of 2.5 on the variance of the (VV/VH) time series determines whether the signal has an important variation, which corresponds only to rice cultivation. The accuracy of the proposed decision tree classification is further presented in Section 4.
## 4 Discussion  
### Measurement Considerations  
After pre-processing, some fluorescence values appear to be negative, which is impossible under natural conditions. The negative values are caused by the fact that, at the beginning of the spectral range of the filter, the filter offered insufficient performance. While the filter normally cuts off light beginning at 650 nm, this standard is difficult to achieve, as the value of \(\tau\) cannot immediately decrease to 0 from 650 nm. Thus, when the fluorescence is calculated, the value of \(E_{u}\tau\) might be larger than that of \(E_{u}\). As a result, the value of \(E_{u}-E_{u}\tau\) may be negative. Therefore, the upward and downward fluorescence resulted in negative values after pre-processing.  
Some fluorescence values at 650 nm are very large. Because the filter eliminates the light from 650 nm to 800 nm, \(1-\tau\) will be closer to 0 before 660 nm. Since \(F_{u}\) and \(F_{d}\) were calculated by dividing their values by \(1-\tau\), the upward and downward fluorescence will result in a large value before 650 nm. These errors were rectified by reducing the fluorescence values before 660 nm and thereby had negligible influence on the model evaluation because most of the fluorescence was emitted away from 660 nm to 800 nm.  
For the reflectance and transmittance data, there are three intervals; all three have minute errors in measurement due to instrumentation. For certain measured data, the reflectance and \(1-\)transmittance curves overlapped. This overlap of the detectors' wavelengths leads to the first two spikes. Because the fluorescence appeared from the 680 nm to 800 nm wavelength region, the intervals would not influence the results in a significant manner.  
In some measurements, the percentages of the measured reflectance and \(1-\)transmittance curve overlapped from 800 nm to 1400 nm. This was due to the fact that the leaves have non-Lambertian reflectance; as a result, the light was reflected in the form of diffused reflectance. The detector on the top also received part of the reflected light. As a portion of the reflectance missed the detector, the absorption was low. In extreme cases, the absorption was lower than 0, and the curves overlapped. Data with evident measurement errors were thus excluded from the simulation.
# Emerging Topics in Joint Radio-Based Positioning, Sensing, and Communications
## 3 Emerging Topics in JPSAC Context  
The emerging trends and topics in the ISAC, radio SLAM, and JPSAC contexts are discussed in the following subsections. Examples of open research questions are given in each subsection.
# Multi-Constraint and Multi-Policy Path Hopping Active Defense Method Based on SDN
## 4 Design of Multi-Constraint Multi-Strategy Hopping Algorithm
### Hopping Strategy Execution Algorithm
Finally, it determines whether the remaining bandwidth of the current communication path exceeds the threshold. If it exceeds the threshold, it indicates that the network is under attack or the amount of data transmitted is large. At the same time, mark this path as false, and monitor it. As long as this path is false, the weight of the remaining bandwidth of the path is used as the basis for the final hopping path selection. To enhance the unpredictability of path hopping, generate a random number between 0 and 1, accumulate the weights of the paths in the alternative path space, and when the random number is less than or equal to the accumulated weight, select this path as the hopping path and update the use time of this path, as shown in steps 15 to 25. If it does not exceed the threshold, it indicates that the network is communicating normally. At this time, the main focus is on resisting eavesdropping, and the hopping path is selected based on the weight of the key nodes. Repeat the above steps, as shown in steps 26 to 31. This algorithm adaptively switches different object weight hopping strategies according to different network attacks, enhancing the defense while reducing the possibility of similar paths and multi-path intersecting nodes reappearing in multiple cycles. In addition, because of the different weights, the hopping cycle of the path is also dynamically changing, which further enhances the unpredictability of path hopping and increases the difficulty of the attacker's attack.
Today, monitoring can make use of modern techniques for measuring displacements and other geometric quantities, such as detection and measurement by using radio waves (RADAR), or light (LiDAR), photogrammetry, multispectral satellite images, radar synthetic aperture (SAR) [15], infrared thermography, and image analysis methods, including digital image correlation (DIC),ground penetration radar (GPR) and remote acoustics [16]. Another important issue is the classification of buildings and neighborhoods for carrying out emergency plans [17; 18].
## 5 Iron, ROS and Iron Chelators That Can Cause DNA Damage in Cancer
### Iron Chelators and ROS  
There can be confusion regarding iron chelators' exact role and purpose when considering iron chelators and ROS. If iron chelators remove iron, they must reduce ROS and return to homeostasis. This is true for iron chelators that do not result in redox-active complexes. Hexadentate chelators are often used to treat iron overload, such as Deferoxamine, as they are not redox-active. Iron chelators that form redox-active complexes, often bidentate and tridentate iron chelators, have free sites for redox cycling and thus can promote free radical generation [128]. Therefore, the stichometry of iron to the chelator is essential. This was shown in the iron chelator 2-dimethyl-3-hydroxy pyrid-4-one, which potentiated H\({}_{2}\)O\({}_{2}\) oxidative DNA damage; however, when prolonged exposure was maintained, it resulted in a protective effect in normal liver cells [170]. The iron complex formed after iron chelation is vital; in some cases, it can act as a reductant or an oxidant. This can be due to the iron complex's localisation in different cellular organelles. This, in theory, presents two ways to approach ROS in cancer, even more specifically when addressing iron chelation for cancer. The first method is to either reduce ROS and inhibit ROS signalling by chelating iron and preventing Fenton chemistry. The second method increases ROS by using an iron chelator with a redox-active complex to selectively kill cancerous cells [160]. The latter approach can be seen in Figure 5, where the iron chelator increases ROS via redox-active iron complexes resulting in DNA damage. All iron chelators discussed that induce ROS have their chemical structure and iron binding groups displayed in Supplementary Figure S1.
# Superinsulation Materials for Energy-Efficient Train Envelopes
## 3 Methods
### Thermal Conductivity Measurements  
The thermal conductivity of the selected VIP and silica aerogel products was measured with two guarded hot plate devices in 2018.  
Of the two thermal conductivity measuring devices, the larger one had a measuring zone of 300 \(\times\) 300 mm\({}^{2}\), and a symmetrical setup, with a hot plate in the middle sandwiched by two nominally identical specimens of the tested material below and above, with sample sizes of typically 700 \(\times\) 700 \(\times\) 20 to 700 \(\times\) 700 \(\times\) 250 mm\({}^{3}\). This setup in turn was sandwiched by one cooling plate on top and one below. The smaller device was only able to take one sample, of the preferred size of 65 \(\times\) 65 \(\times\) 10 to 65 \(\times\) 65 \(\times\) 15 mm\({}^{3}\), with larger sizes being possible.  
The larger device adhered to EN 12667 with \(<\)\(\pm\)3% and had a reproducibility of the measurement of better than \(\pm\)2% in general and \(<\)\(\pm\)5% with VIPs of \(\geq\)400 \(\times\) 400 mm\({}^{2}\)[32]. The smaller device was made in the style of EN 12667 but with an absolute precision better than \(\pm\)10%, when very different material types are compared [33; 34].  
The VIPs were measured before and after a test period in a train of the Swiss railway operator Rhatische Bahn (RhB). For that, after the first measurement of thermal conductivity, two panels were fixed with double-sided tape on the inside of the thermal envelope of one of the technical cabinets of a control car of the train. The control car was then operative for two months before the panels were carefully removed, and their thermal conductivity was measured again. The panels were also checked for mechanical damage after this test period.
# Pressure-Reducing Design of 3D-Printed Diabetic Shoe Midsole Utilizing Auxetic Lattice Structure
## 4 Discussion  
### Effects of Auxetic Structural Design on Plantar Pressure Distribution  
These research findings corroborate the characteristic ability of auxetic lattice structures to reduce peak contact pressures and achieve optimized pressure distributions [16; 44; 45], particularly in the application of ergonomics-related therapeutic auxiliary devices [46]. Under ideal simulation conditions, wearing the A60 midsole kept the peak plantar pressures below 200 kPa [47], achieving effective pressure relief. A60 provides design references for 3D-printed footwear, especially those emphasizing motion protection and cushioning, for creating daily exercise shoes suitable for diabetes patients. However, the midsoles used for FEA in the present study require refinement of several details. The overall design of the midsole should be thinner at the front and thicker at the back to accommodate the trajectory of the plantar pressure center moving from the heel toward the forefoot. The presence of imprints from orthogonal beams in areas of higher plantar pressure in Figure 7a suggests that the lattice beams on the upper surface of the midsole should be widened to increase the support area. However, this does not affect the achievement of this study's objectives. Current research on diabetic shoes primarily focuses on custom insole designs for pressure relief. This study's A60 midsole, without the need for customization, similarly reduces plantar pressures by 19.68-55.25% and 16.19-54.39% in walking and running conditions, respectively, compared to the non-auxetic N90 midsoles. The auxetic A60 midsole provides pressure relief comparable to that achieved with custom diabetic insoles [47; 48], suggesting that auxetic midsoles may have a self-adaptive quality. However, this does not imply that auxetic lattice midsoles can completely replace custom insoles, as custom insoles may offer higher conformity to the plantar foot shape, potentially enhancing subjective comfort for the wearer [49; 50]. Therefore, future research must explore the combined offloading effects of auxetic lattice midsoles and custom insoles.
## 7 Discussion and Challenges
### Future Usage: DT Interaction and Enhanced Maintenance Operations
#### 7.3.1. Organisational, Human and Economic Changes
Another example is given by [PERSON] et al. where they present the different criticalities that need to be taken into account when developing and implementing DT and XR devices to prevent operators' risk during the O&M phase [64]. However, some authors have also observed that the introduction of these new technologies creates a need for new skills to allow the operators to use them. This Operator 4.0 [91] does not need to create and capture the data, thanks to the introduction of smart and embedded sensors. Therefore, they need to develop new analytics skills that will help them to perform advanced operations using the collected data [36; 78; 91]. However, the operators do not need to have all the analytics skills. Some authors have therefore observed that there is a need to define the specific role of an operator and use this classification to display only specific information in the function of the user's role [36; 47], further improving the security and the privacy of the shared data. This change in the role of the collaborators reminds us of the importance of human involvement in operations. This importance was highlighted in 2020 to define the new industrial revolution: Industry 5.0 [94]. The need to change the maintenance organisation is even more important with the impact of the COVID-19. It is now necessary to think about new methods of remote collaboration, whether through the centralised source that is the DT but also through the use of XR technologies [16; 22; 25; 29; 32; 33; 38; 40; 41; 65; 69; 70; 72; 78; 79]. This collaboration can be achieved using an MR device, as proposed by [PERSON] et al. for aircraft maintenance tasks [72]. It can also be performed in a collaborative virtual environment accessible with a VR device where users can work together on the 3D representation of a piece of equipment, as shown by [PERSON] et al. for inspecting a 3D representation of a bridge [79]. [PERSON] et al. also observed that this collaboration in virtual space can also allow for collaborative work on the design of a system, such as a building, even if the stakeholders cannot move in reality, by allowing them to observe it at different scales [78].
# Towards Secure Searchable Electronic Health Records Using Consortium Blockchain
## 2 Background and Related Works
### Relate Works
#### 2.2.2 Blockchain Enabled Searchable Encryption  
A blockchain-based symmetric searchable encryption (SSE) system for electronic medical record sharing was proposed [10] to enhance data searchability. In this case, SSE with AES will help dynamic searchable symmetric key encryption and address key sharing problems, but the multi-keyword search cannot be supported [6]. Regarding this, in [34], a trustworthy and private keyword searchable privacy protection method based on blockchain is developed, which employs searchable encryption to enable an encrypted data search. [PERSON] et al. [35] proposed a blockchain privacy protection strategy based on searchable symmetric encryption, which ensured both sides' fairness.  
However, most techniques only offer single-keyword searches and cannot be used for file updates, limiting the scheme's imperfection. The authors of [36] developed a blockchain-enabled public key encryption system with multi-keyword search (BPKEMS) to solve these issues, and their approach also enables file updates. However, the security issue related to using PEKS schemes is a keyword guessing attack (KGA). To address keyword guessing attack (KGA) issues, the authors of [37] present certificateless searchable public-key authenticated encryption scheme with a designated tester (CL-dPAEKS). Public-key Authenticated Encryption with Keyword Search (PAEKS) in [8] provides a different approach to solve the same problem. Besides that, the authors of [9] present SEPSE to resolve online and offline keyword guessing and also the single point of failure problem. SEPSE uses PEKS, which supports key renewal to replace a new key on each key server regularly to avoid the key compromise. SEPSE is based on threshold blind BLS signature and we can decrease the computing time for enhanced performance by using ECC encryption techniques [38].