esa-sceva/satcom-chunk-collection huggingface dataset:
# Pilot-Aided Frame Synchronization in Optical OFDM Systems
## 3 Results and Discussions
It is shown that the estimated start of a pilot symbol in DCO-OFDM and ACO-OFDM are at the precise timing point at SNR \(\geq 4\) dB and SNR \(\geq 8\) dB respectively using the PA method in both channel model considered. However, there is an average of the timing offset of about 2 and 217 samples in DCO-OFDM and ACO-OFDM respectively at SNR \(=2\) dB. In comparison with the modified Park's method, results show that the timing metric (6) is unable to achieve precise synchronization for the range of SNR considered. The metric has mean offset floor of about 165 and 265 samples in ACO-OFDM and DCO-OFDM, respectively. The performance plot shows the robustness of the PA frame synchronization timing metric in the presence of AWGN and indoor VLC channel. Figure 3: Plot of normalized average of the modified Park’s timing metric (6) for an ACO-OFDM system with \(N=256\), \(U=5\), \(cp=N/8\), SNR \(=10\) dB, and 4-QAM. Figure 5 shows the CCDF plot of PAPR to illustrate the capability of using the pilot sequence utilized for frame synchronization to achieve PAPR reduction. The PAPR CCDF of PA ACO-OFDM and DCO-OFDM signal using \(U=5\), \(R=5\), 4-QAM, 127 active subcarriers and an oversampling factor of 4 is shown in Figure 5. This figure also presents the plots of the basic ACO-OFDM and DCO-OFDM counterpart with no PAPR reduction technique for comparison. The result for the basic DCO-OFDM shows that 1 out of every \(10^{3}\) DCO-OFDM frames has its PAPR greater than 14.1 dB. However, the PA technique is capable of minimizing this threshold value such that 1 frame has its PAPR greater than 11.9 dB out of every \(10^{3}\) frames. This implies a PAPR reduction gain of about 2.2 dB at CCDF of \(10^{-3}\). Similarly, about the same PAPR reduction gain of 2.2 dB at CCDF of \(10^{-3}\) is obtained when the PA technique is applied to ACO-OFDM system. Further comparison of the PA ACO-OFDM and DCO-OFDM with their basic counterparts shows that the PAPR reduction gain increases as CCDF decreases using the PA technique. The high signal peaks reduction capability of the PA technique implies that the technique can be implemented in O-OFDM system utilizing power-limited optical sources to ensure the transmitted signal is less susceptible to clipping due to the limited dynamic range of optical source. Figure 4: Mean of the timing offset in DCO-OFDM and ACO-OFDM using 1000 frames with \(N=256\), \(U=5\), \(cp=N/16\), and 4-QAM. Figure 5: The complementary cumulative distribution function (CCDF) plot illustrating the peak-to-average power ratio (PAPR) reduction capability of PA technique in ACO-OFDM and DCO-OFDM using \(U=5\), 4-QAM and 127 active subcarriers (Pc is the probability that PAPR exceeds a particular defined value of PAPR).
# Real-Time, Content-Based Communication Load Reduction in the Internet of Multimedia Things
## 3 Methodology
### System Composition  
The system that has been designed by the authors is divided into four major components comprising of: (1) Data Acquisition; (2) ROM Identification; (3) Load Reduction; and (4) Secure Transmission. The system, as shown in Figure 1, was implemented using the OpenCV library, written in the Python programming language, to facilitate a variety of functions for image and video processing. The proposed method uses an implementation of the JPEG codec in OpenCV. In data acquisition, video frames are captured as YUV video of Phase Alternating Line (PAL) TV/video system [57] before conversion back to the more convenient, as far as the current video processing of the authors is concerned, Red/Green/Blue (RGB) color space. Thus, frame difference images are formed in that RGB space. The difference frame calculated at any one instance is reduced to specified intensity values. A ROM is separated from an image depending on the amount of motion change within each identified region. The ROM is then compressed and encrypted before it is sent across the IoMT network. A more detailed overview of each module is now given.  
It is important to notice that for some security applications, there may not be a need to convert from YUV to RGB, as color images may not be required. In fact, if difference imaging was the only application envisaged then only the Y channel could be sufficient and will result in saving of resources. However, if further video analysis is to be performed then conversion from YUV to RGB color space may well be required, such as for gait recognition at airports [58] or facial recognition using the Kinect sensor [8]. Therefore, this paper considers a system with the more general case, which readers can reduce according to their individual application requirements.  
Figure 1: A modular representation of the system.
###### Abstract  
Geocells are three-dimensional honeycomb-reinforced geotechnical materials composed of strips and junctions. Its junctions can support and transmit forces in several directions. The performance of geocells has a considerable impact on engineering applications. However, the testing program of geocell junctions still lacks standardization, and limited research has been undertaken regarding the failure mechanisms of junctions when subjected to various stress types. In this paper, four test procedures for HDPE welded geocell junctions were performed, including weld tensile, shear, peeling, and splitting strength tests. The influence of tests under different clamping distances (10.5 mm, 25 mm, 50 mm, and 100 mm) was analyzed, and the stress-strain behavior, peak elongation, and peak and residual strength of junctions under various force states were analyzed in detail. Finally, considering the strength and deformation, the slope laying method of geocells was proposed. The results show that the tensile strength and shear strength decrease with the clamping distance, whereas the peeling strength and splitting strength remain essentially unchanged. Under a 100 mm clamping distance, the tensile strength and shear strength are decreased by 4.51% and 14.08%. Geocells spreading vertically along the surface on a subgrade slope are thought to be more reliable, improving the geocell's service life in slope protection. The test results can be used to improve a standardized geocell junction testing procedure as well as to guide, evaluate, and enhance the quality and application dependability of geocells.  
HDPE welded geocell; junction; tensile test; clamping distance; failure mechanism +
Footnote †: journal: Applied Sciences
## 4 Results and Discussion
### Waveform Measurement of the Output Voltage \(V_{ce}\) of Transistor 9013  
To prove whether the photosensitive resistor divider could faithfully translate flashlights into a corresponding Morse code, we measured the voltage difference (\(V_{CE}\)) across the collector and emitter of 9013 using an oscilloscope. In Figures 17 and 18, the voltage waveforms are magnified by ten-fold. We could see the obvious wide pulses and the other narrow pulses that represent \"dashes\" and \"dots\" respectively. Furthermore, both signals are correctly translated back to their original code, 1 and 1832, and then transmitted.
## 5 Experimental Results
### Comparison with Other Approaches  
Table 3 shows a comparison with the state-of-the-art power-efficient VLC drivers based on PWM DC/DC converters able to reproduce advanced modulation schemes.  
The proposed TIBuck DC/DC converter outperforms traditional Buck DC/DC converter solutions in terms of efficiency, bit rate and moderate EVM\({}_{\text{rms}}\),, even operating at higher switching frequency. Moreover, the hardware complexity of the proposed solution is similar to that of the Buck DC/DC solutions presented to design high-bandwidth VLC drivers (i.e., two-phase structures with high-order filter).  
The proposed TIBuck DC/DC converter's natural way to split power simplifies previous approaches using this technique, because it does not need two input voltage sources (one of which is isolated) or one isolated DC/DC converter. In addition to simplicity, high communication capabilities and high efficiency are maintained, with good design of the auxiliary Buck DC/DC converter.  
It is important to note that Table 3 highlights the ratio between the maximum amplitude and the average value of i\({}_{\text{o}}\)(t) (i.e., i\({}_{\text{omax}}\)/2I\({}_{\text{o}}\)), which gives us an approach to assess of the ratio between communication power and lighting power. The TIBuck DC/DC converter maximizes communication power compared to other approaches, which minimize the amplitude of the communication to reach high efficiency (e.g., [27]).
## 4 Conclusions  
In this study, we investigated, for the first time, the effect of inertial forces (\(Re\
eq 0\)) on the magneto-hydrodynamic flow of a second-grade fluid through a ciliated conduit. The nonlinear system of partial differential equations was solved by the Homotopy Perturbation Method and the software Mathematica. The combined influences of the Reynolds number \(Re\), Hartmann number \(M\), fluid parameter \(\lambda_{1}\) and porosity parameter \(K\) on the velocity profiles, pressure gradient and stream function were quantified and discussed in detail. The main results gained from this analysis can be summarized as follows:  
The horizontal velocity component decreases with increasing values of the Hartmann number \(M\) in the centre of the channel. On the contrary, it increases with increasing values of the Reynolds number \(Re\), the porosity parameter \(K\), and the fluid parameter \(\lambda_{1}\). The vertical velocity component vanishes in the centre of channel and behaves like a sinusoidal wave.  
A favourable pressure gradient in the axial direction uniformly increases with the Hartmann number \(M\) and decreases with the porosity parameter \(K\). It shows a dual behaviour for the fluid parameter \(\lambda_{1}\) and the Reynolds number \(Re\), whereas a favourable pressure gradient in the vertical direction is symmetric around the channel centre. It decreases for large values of the Hartmann number \(M\), while it increases for larger values of the fluid parameter \(\lambda_{1}\) and the Reynolds number \(Re\).  
The size of the trapped bolus reduces by increasing the Hartmann number \(M\) and expands by increasing the porosity parameter \(K\) and the fluid parameter \(\lambda_{1}\). However, both the size and the number of trapped boluses of a second-grade fluid in a ciliated channel increase by increasing the Reynolds number.  
The skin friction coefficient (or shear stress) of the second-grade fluid exhibits a linear relation for \(\varepsilon=0.1\), whereas this relation becomes nonlinear for increasing values of the cilia length.  
The results are useful to detect the frequency and motion of motile cilia under diseased conditions such as cystic fibrosis or bronchopneumonia. The application of a magnetic field for magnetic resonance imaging can detect a viscous fluid flow induced by ciliary motion. For future perspectives, the study will be extended to consider the influence of the temperature and surrounding environment on fluid transport.  
Conceptualization, K.M., methodology, K.M. and N.M.; software, N.M.; validation K.M. and S.P.; formal analysis, A.M.S.; investigation, N.M.; writing--original draft preparation, K.M. and N.M.; writing--review and editing, S.P.; supervision; A.M.S.; funding acquisition; S.P. All authors have read and agreed to the published version of the manuscript.  
Funding: This research received no external funding. Institutional Review Board Statement: Not applicable. Informed Consent Statement: Not applicable. Data Availability Statement: Not applicable. Conflicts of Interest: The authors declare no conflict of interest. Nomenclature Symbols
## 5 Communication Performance in a Multi-Luminaire Scenario
### Simulation Results and Discussion  
In this section, we present the simulation results for a QADA receiver in a typical room with four luminaires. Each luminaire is transmitting with an optical power of 1.57 W which is enough to provide the required illumination level in the room. See Appendix A for more details.  
Figure 13 shows the BER versus the location of the QADA in the room. As in Section 3, two QADAs with different FOV-Cs are considered. The noise level represents a typical-case scenario of \(p_{n}=0.29\,\upmu W/\left(\text{cm}^{2}\cdot\text{nm}\right)\). We can see that the QADA receiver is capable of providing very good performance in all locations within the room when the FOV-C is \(63.4^{\circ}\). The signals from all luminaires are decoded with a BER that is less than \(10^{-4}\). Please note that in typical VLP systems, three luminaires are sufficient for the receiver to estimate its location. When the FOV-C is reduced to \(45^{\circ}\), as long as the luminaires are within the FOV-C of the receiver, the signals are received with a very low BER. However, because of the smaller FOV-C, in some locations within the room, the receiver is unable to capture the signals from some luminaires. For both values of FOV-C, we can see that the FOV-P for each luminaire is within the low BER area. So, we can conclude that the communication characteristics of a QADA are not going to be a limiting factor when the receiver is used for VLP applications.  
Figure 13: BER versus QADA location in a room equipped with four luminaires when a spectral irradiance of \(p_{n}=0.29\,\upmu W/\left(\text{cm}^{2}\text{.nm}\right)\) and with the receiver parallel to the plane on which the luminaire is located with a FOV-C of (**a**) \(45^{\circ}\); (**b**) \(63.4^{\circ}\).
# Utilizing Graphite Waste from the Acheson Furnace as Anode Material in Lithium-Ion Batteries
## 1 Introduction
While GW is graphitized, it may still contain impurities or exhibit non-uniform crystalline structures that could negatively impact the performance of the resulting anode material. Therefore, a thorough characterization of GW properties is essential to ensure it meets the performance standards required for LIBs. Previous studies have shown that impurities in graphite can reduce conductivity and increase resistance, thereby diminishing the electrochemical performance of LIBs [25; 26; 27; 28]. Another concern is the physical and morphological properties of GW, such as particle size, specific surface area (SSA), and tap density (TD), which must be optimized to align with commercial anode material benchmarks. These parameters directly influence the material's ability to perform under the rigorous demands of LIB applications. For instance, excessively high SSA can result in lower initial Coulombic efficiency (ICE), while low TD can reduce the energy density of the anode. In this study, granulated coke, a waste discarded after the Acheson process--a core process for graphite production--was repurposed as a starting material for LIB anodes. This approach seeks to reduce the production cost of anode materials while simultaneously improving the performance of granulated coke as a viable anode material through further processing. We focus on evaluating the structural and electrochemical characteristics of  
Figure 1: Acheson furnace for graphite manufacturing. GW to determine its compatibility with commercial anode materials (CAM). This includes optimizing key parameters such as particle size, SSA, and TD, as well as applying advanced processing techniques such as spheronization and carbon coating to improve its performance [29; 30]. The successful adoption of GW for anode production could provide significant economic and environmental benefits, contributing to a more competitive and sustainable battery industry. By reducing reliance on virgin graphite and minimizing the energy-intensive graphitization process, this approach offers a pathway toward more cost-effective and environmentally friendly LIBs.
# Setonix: Blockchain-Based Hierarchy Domain Name System for Web3
## 1 Introduction
### Basic Concepts and Services Relevant to This Paper
#### 1.1.1 Operation of Traditional DNSs  
The currently operating DNS generally manages each set of letters in a domain, named based on dots ('\(\cdot\)'), by dividing them into root, TLD (top-level domain), and SLD (second-level domain) servers. The process of resolving addresses follows a hierarchical structure that recursively goes through root \(\rightarrow\) TLD \(\rightarrow\) SLD [19]. This prevents all requests from being concentrated on a single root server and has the advantage of facilitating the management of subdomains for each domain. Furthermore, this hierarchical system allows for efficient distribution of DNS queries and reduces latency by caching responses at various levels.
# Time-Domain Dynamic Modeling and Analysis of Complex Heavy-Duty Gearbox Considering Floating Effect
## 2 LTC Modeling Approach of Heavy-Duty gearbox
### Detailed Formulations
#### 2.2.3. Bearing Force Analysis between Carrier and \(i\)th Planet Gear  
The interaction between the carrier and the planet gear can be represented using an equivalent spring damper force and a friction torque. \(R_{P}\) denotes the distribution radius of the planets, and \(\gamma^{i}_{CP0}\) is the initial distribution angle, namely the angle between the center line of the \(i\)th planet and the carrier along the X axis. As such, the deformation of the \(i\)th planet relative to the carrier is  
\[\delta^{i}_{CP-x}=x^{i}_{P}-\left[x_{C}+R_{P}\cdot\cos\left(\theta_{C}+\gamma ^{i}_{CP0}\right)\right]\&\delta^{i}_{CP-y}=y^{i}_{P}-\left[y_{C}+R_{P}\cdot \cos\left(\theta_{C}+\gamma^{i}_{CP0}\right)\right]. \tag{29}\]  
The rotational angle of the \(i\)th planet relative to the carrier is \(\delta^{i}_{CP-\theta}=\theta^{i}_{P}-\theta_{C}\). Therefore, the reaction force and torque on the center of the \(i\)th planet are computed as follows:  
\[\begin{split} F^{i}_{CP-x}&=-k_{CPB}\cdot\delta^{i }_{CP-x}\\ F^{i}_{CP-y}&=-k_{CPB}\cdot\delta^{i}_{CP-y}\\ T^{i}_{CP-z}&=-\left(\mu_{CPB}\sqrt{\dot{F}^{i}_{ CP-x}+\dot{F}^{i}_{CP-y}{}^{2}}\cdot d_{CPB}/2+c_{CPB}\cdot\dot{\delta}^{i}_{CP- \theta}\right)\cdot\text{sgn}(\dot{\delta}^{i}_{CP-\theta})\end{split}, \tag{30}\]  
where \(k_{CPB}\) is the bearing stiffness, \(d_{CPB}\) is the nominal diameter of bearings, \(\mu_{CPB}\) is the coulomb friction coefficient, and \(c_{CPB}\) is the viscous damping coefficient.
# Energy Harvesting Methods for Transmission Lines: A Comprehensive Review
## 4 State-of-the-Art Energy Harvesting Methods for Transmission Lines  
EH circuits are designed to collect energy from ambient sources to provide a stable supply to the other modules [37]. Continuous energy supply is an important research topic for IoT and WSNs applications [7] because the power supply is a bottleneck for developing autonomous transmission line monitoring systems [38]. Monitoring and maintenance of transmission lines can be performed by line robots or by using line-mounted distributed wireless sensors, which typically use batteries as the main power source, but as explained at the expense of environmental impacts and maintenance costs [38], and presenting significant maintenance difficulties in remote areas [39].  
This section reviews the EH methods that can be effectively applied to transmission lines. However, some EH technologies are not included in this section, such as wind collectors that rely on moving parts due to insulation issues and sensor costs [38], because they cannot be effectively applied in power transmission lines.
# Prism-Based Spatial Heterodyne Spectrometer with a Fixed Fringe Localization Plane
## 2 Principles and Designs
### Anti-Aliasing Design  
One of the major limitations of SHS is that the symmetry in achieved spectrum from the Fourier transform duplicates all spectrum features at locations on either side of the Littrow wavelength \(\lambda_{0}\), which is referred to as aliasing. If \(\lambda_{1}>\lambda_{0}\), the spatial frequency \(f\) of the interferogram corresponds to \(\lambda_{1}\) one-to-one; if \(\lambda_{2}<\lambda_{0},f\) also corresponds to \(\lambda_{2}\) one-to-one. Therefore, a spatial frequency \(f\) corresponds to two wavelengths, \(\lambda_{1}\) and \(\lambda_{2}\). We need an additional mechanism to tell the difference between \(\lambda_{1}\) and \(\lambda_{2}\).  
For grating-based SHSs, each grating can be tilted by a small, constant angle around the axis of symmetry which is perpendicular to the tuning spindle. This tilting produces a constant frequency in a direction orthogonal to the interference fringes generated by dispersion. However, in prism-based SHSs, if the mirrors are tilted, the FLP of the fringes produced by dispersion is at a different location than the FLP of the fringes orthogonal to the direction of dispersion. If the prisms are tilted, this will lead to a change in the refractive angle, which may have an effect on the accuracy of the spectrum [20]. This is acceptable if the resolution of the spectrometer is not very high.  
We consider tilting only half of the areas of the refracting surfaces of the prisms of both arms by a small angle (0.1\({}^{\circ}\)) around their axes of symmetry which are perpendicular to the tuning spindle, as shown in Figure 5b. This results in both a 1D interferogram and a 2D interferogram on the FLP, where the 1D interferogram recovers the exact spectrum and the 2D interferogram is used to differentiate between \(\lambda_{1}\) and \(\lambda_{2}\). Now, we describe the principle of the 2D interferogram. The beams pass through half of the refracting surfaces that are tilted and not only produce the angle \(\beta\) with the optical axis in the dispersion plane, but also produce an angle \(\gamma\) with the optical axis in the direction orthogonal to the dispersion plane. When the beams are recombined by the beam splitter, the angles become \(+\gamma\) and \(-\gamma\), because the beam from one arm is transmitted and the beam from the other arm is reflected. The plus or minus sign of \(\gamma\) is determined by which arm the beam is coming from and is independent of the wavelength, which makes the states of the outgoing beams corresponding to \(\lambda_{1}\) and \(\lambda_{2}\) different. The interferograms are modulated in the direction orthogonal to the dispersion plane. In the simulations in this paper, when \(\lambda_{1}>\lambda_{0}\), the interferogram is deflected clockwise and the impact spectrum of the 2D power spectrum is located in the first and third quadrants; when \(\lambda_{2}<\lambda_{0}\), the interferogram is deflected counterclockwise and the impact spectrum is located in the second and fourth quadrants.
These findings hold promise for enhancing the safety and reliability of future networks, including 6G. The study also advocates for a paradigm shift toward creating safer, environmentally conscious communication networks and calls for updating safety regulations to align with current radiation exposure levels in our environment. As a consequence of multiple conflicting research findings, this has become crucial for determining whether 5G and B5G technologies are genuinely safe for users. The main contributions and objectives of this review article are as follows:  
* To provide categorical information on RF-EMF exposure from UE and base stations. * To present a comprehensive review of the impact of high-frequency communication technologies on human cognitive abilities. * To discuss the challenges and opportunities of implementing the smart environment in parallel with the deployment of high-frequency infrastructure. The article is organized as follows. Section 2 outlines the detailed methodology employed in this study, ensuring a robust approach. In Section 3, a comparative analysis of the findings is presented, enabling insightful comparisons, limitations, future scopes, and observations. Finally, Section 4 concludes the paper.