esa-sceva/satcom-chunk-collection huggingface dataset:
# An Analysis of Rock Bolt Dynamic Responses to Evaluate the Anchoring Degree of Fixation
## 2 Materials and Methods
### Simple Analytical Model  
The frequency of the resonance of a bar can be qualitatively related to the degree of mechanical coupling with the surrounding rocks and can indicate the quality of the grouting. A higher frequency of natural resonance indicates a good quality of grouting, whereas a lower frequency could be related to a poor coupling.  
A simple model of the behavior of rock bolts was considered to model the response by assuming the following (Figure 9):  
1. The rock bolt was a clamped bar where at least one end was well coupled to the rock.
2. The rock bolt was a free bar where the mechanical coupling was extremely poor all over the bar.  
This procedure provided a preliminary analysis of the behavior of the rock bolts under the condition of extremely poor grouting.  
The natural frequency depends upon the density and elasticity of the material from which the bars are formulated. The amplitudes for the higher modes are much smaller than the fundamentals.  
Figure 9: (**left**) Main resonant frequency (f1) and upper modes (f2 and f3) of the natural frequencies for a clamped bar; (**right**) main resonant frequency of the upper modes of the natural frequency for a free bar. Courtesy of [PERSON].  
A comparison of the theoretical response between the free and clamped rods (Figure 10) for the first mode of vibration as well as for the higher modes is provided in Table 3.  
The main resonant frequency can be computed according to the geometric thickness (a) and length (L) and the mechanical properties of the material, the density (d) and Young's modulus (E). For a thin clamped bar, the frequencies are  
\[f_{1}\approx 0.162\ \frac{a}{L^{2}}\ \sqrt{\frac{E}{d}}\]  
\[f_{n}\approx 2.81\bigg{(}n-\frac{1}{2}\bigg{)}^{2}f_{1}\]  
For a thin free bar, they are  
\[f_{1}\approx 1.028\ \frac{a}{L^{2}}\ \sqrt{\frac{E}{d}}\]  
\[f_{n}\approx 0.441\bigg{(}n+\frac{1}{2}\bigg{)}^{2}f_{1}\]  
where n is an integer number, referring to the upper modes of the resonant frequency.  
Direct pull-out testing is always relevant, not only for the short- and long-term evaluation of anchoring performances but also because the stiffness of the grout can be calculated, as it depends on the embedment length, the plate diameter, and the mix characteristics of the grout itself [10].  
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline  & **f1 (Hz)** & **f2** & **f3** & **f4** & **f5** & **f6** & **f7** & **f8** & **f9** & **f10** \\ \hline \hline \multicolumn{1}{c}{Clamped rod} & 5.86 & 52.7 & 146.5 & 287.2 & 474.8 & 709.2 & 990.6 & 1318 & 1694 & 2116 \\ \hline \hline \multicolumn{1}{c}{Free rod} & 52.5 & 145.9 & 286.0 & 472.8 & 706.3 & 986.5 & 1313 & 1687 & 2107 & 2574 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Resonance frequencies for a clamped rod and free rod, based on a steel rod 0.022 m in diameter and 1.4 m in length.  
Figure 10: Sketch of the rock bolt and grouting with the tetrahedral meshing element for the finite analysis model.
# Design, Deployment and Evolution of Heterogeneous Smart Public Lighting Systems
## 6 Deployment and Configuration of a Smart Lighting Infrastructure
### Step 3. Network Partitioning and Lighting Tasks Configuration
Network engineers are looking at lighting infrastructures as the solution for the ultra-dense placement of 5G base stations across smart cities [3; 99]. For cellular network providers, the advantages of equipping streetlights with 5G base stations include:  
* the availability on the installation site of the power supply, which avoids separate cabling costs,
* a regular and effective deployment, as streetlights are typically tall and evenly spaced, which eases the network planning phase and reduces the occurrence of coverage gaps,
* the availability of a single \"counterpart\" (the public light holder), who leases the sites for hundreds (possibly, thousands) of base stations,
* given the location of streetlights along roads, the possibility to support location-based roadside-to-vehicle communications for intelligent-transport services or autonomous driving. Regarding the cost of integrated 5G/smart lighting infrastructure, one observes that modern light fixtures are composed by separate modules (lamp+light controller, WiFi access point, photometrical unit, IP camera,...) connected each other atop the pole. The 5G transceiver will be simply an additional, removable, module of the light fixture, whose cost would be in charge of cellular operators (as it happens in the case of traditional base stations). Contrarily, the smart lighting operator would have an income given by the site-rental fees paid by the cellular operator. Examples of initiatives aimed at developing 5G-enabled smart lighting fixtures are provided in [99; 100].
# Smart-Median: A New Real-Time Algorithm for Smoothing Singing Pitch Contours
## 3 Current Contour Smoother Algorithms
### Kalman Filter  
The Kalman filter is a set of mathematical equations that provides an efficient recursive means to estimate the state of a process in a way that minimises the norm of the squared error. The Kalman filter uses a form of feedback control, assessing the process state and then obtaining feedback in the form of (noisy) measurements. The equations for the Kalman filter have two parts: time update equations and measurement update equations. The time update equations operate as predictor equations, while the measurement update equations are corrector equations. Thus, the overall estimation algorithm is close to a predictor-corrector algorithm, i.e., correcting to improve the predicted value. In the standard Kalman filter, it is assumed that the noise is Gaussian, which may or may not reflect the reality of the system that is being modelled [42]. Thus, the more accurate the model used in the Kalman algorithm, the better the performance.  
The Kalman smoother can be represented in the state space form. Therefore, a matrix representation of all the components is required. Four structure presentations in the contours are considered: 'level', 'trend','seasonality' and 'long seasonality', and a combination of these structures can be considered. Examples of the effects of different variations of the Kalman filter are shown in Figure 2f,g.
# Impact of Intracavity Power Variations toward Ultrashort Pulse Generation
## 6 Conclusions  
In this work, we have investigated the performance of an ultrashort pulse generated by GNP-SA in mode-locked EDFL with the variation of output coupling ratio from 10% to 50%. The preparation of GNP-SA is made using the simple deposition method of mechanical exfoliation. To fabricate the SA, the bulk material of the graphene nanoplatelet is transferred onto a fiber ferrule with the help of the index-matching gel. The thickness of the GNP is minimized by layer-by-layer peeling using Scotch tape until a very thin layer of GNP is formed on the fiber ferrule. The fabricated GNP-SA has a 0.8% modulation depth, an 8.7 MW/cm\({}^{2}\) saturation fluence, and a 63.2% transmission. The insertion of GNP-SA into a ring-cavity EDFL is responsible for ultrashort pulse generations. The property of lasing oscillation is dependent on the intracavity powers. For an output coupling ratio of less than 50%, the lasing wavelength is observed in the long wavelength range within 1557-1559 nm. This indicates that the EDFL operates at a low population inversion level. When the output coupling ratio is increased from 40% to 50%, the lasing wavelength is switched from 1556.8 nm to 1531.9 nm. The intracavity power is decreased, and therefore, the number of signal photons at the entry point of EDF is also reduced. In this situation, the saturation level of optical amplification in the active gain medium is also reduced. As a result, the output power is increased. The maximum output power of 6.05 mW is obtained using a 50% output coupling ratio, and the shortest pulse duration of 810 fs is achieved using a 30% output coupling ratio. From this work, the design of the fiber laser setup is highly influenced by the availability of the signal photon count at the input of EDF, which determines the optical amplification dynamics in the active gain medium.  
Conceptualization, A.F.A., K.Y.L. and M.A.M.; methodology, A.F.A., K.Y.L., M.T.A. and M.A.M.; software, K.Y.L.; validation, A.F.A., K.Y.L. and M.A.M.; formal analysis, A.F.A., K.Y.L., Y.M.A.-M., Y.T.A., M.T.A. and M.A.M.; investigation, A.F.A., K.Y.L., Y.M.A.-M., Y.T.A., M.T.A. and M.A.M.; resources, A.F.A., M.T.A. and M.A.M.; data curation, K.Y.L.; writing--original draft preparation, K.Y.L. and Y.M.A.-M.; writing--review and editing, A.F.A., K.Y.L., Y.M.A.-M., Y.T.A., M.T.A. and M.A.M.; visualization, A.F.A., K.Y.L., M.T.A. and M.A.M.; supervision, A.F.A., M.T.A. and M.A.M.; project administration, A.F.A., M.T.A. and M.A.M.; funding acquisition, A.F.A. and M.T.A. All authors have read and agreed to the published version of the manuscript. National Plan for Science, Technology and Innovation (MAARIFAH), King Abdulaziz City for Science and Technology, Kingdom of Saudi Arabia, award number 3-17-09-001-0007. Data Availability Statement: Data sharing is not applicable to this article. This project was funded by the National Plan for Science, Technology and Innovation (MAARIFAH), King Abdulaziz City for Science and Technology, Kingdom of Saudi Arabia, Award Number 3-17-09-001-0007. The authors declare no conflict of interest.
# Backscatter Communications: Inception of the Battery-Free Era--A Comprehensive Survey
## 9 Challenges and Future Directions
### Open Problems
#### 9.1.2 Eavesdropping Security  
BackCom considers RF carrier signals to reflect information, and these signals may be used for eavesdropping by nearby unwanted tags. Many security measures are taken to address eavesdropper attacks. These measures include the selection of the best relay scheme to avoid the eavesdropper's attack for reliable communication [109]. [PERSON] et al. also addressed the data theft problem by injecting noise-like signals into the carrier waves. These noise-like signals interfere with the eavesdropper's reception to secure BackCom communication [184].  
[PERSON] et al. highlighted the black hole attack, which is a security risk in the collection of data [221]. They also suggested that an ActiveTrust scheme for WSNs to secure data. The techniques highlighted by [PERSON] et al. can leak information from the neighboring laptop or smart device, and it has a range between 2 m (without walls) and 70 m (with walls), and a data rate of 1.6 bps [222; 223]. Therefore, BackCom eavesdropping security needs more attention to establish secure and reliable passive device communications for next-generation 5G networks.
# Accident Risk Analysis of Gas Tankers in Maritime Transport Using an Integrated Fuzzy Approach
## 6 Conclusions
### Contribution to Industry and the Literature  
The synthesis of fuzzy and probabilistic risk assessment techniques in this study enables a multidimensional understanding of accident causality in gas tanker operations. The results highlight the complex interaction between design flaws, operational challenges, environmental conditions, and human factors. Addressing these risks requires a holistic strategy that integrates advanced design methodologies, robust operational controls, real-time monitoring systems, and adaptive emergency management. Future studies may benefit from further use of dynamic simulation models, machine learning tools, and scenario-based validation to improve maritime safety frameworks.  
This study demonstrates the applicability and effectiveness of Fuzzy Delphi, Fuzzy DEMATEL, and FTA in assessing accident and environmental risks associated with gas tanker operations. The results provide valuable insights for improving maritime safety, ensuring operational continuity, and preserving the integrity of the marine environment. By providing a comprehensive and integrated perspective on gas tanker safety, this research contributes to the development of proactive and resilient maritime risk management practices. Continued research and adaptive risk management practices are essential for improving the safety performance of gas tankers and contributing to the overall sustainability of maritime transport.
# The Influence of Interlock Loss between Rebar and Concrete on Bond Performance of RC Member
## 2 Outline of the Loading Experiment for Beams with Different Interlock Conditions  
In order to confirm the effect of interlock on the bond performance of the RC beam, a static loading test was conducted. The interlock area of specimens was set to the values of 0%, 50%, and 100%.
# Validation of Acoustic Emission Waveform Entropy as a Damage Identification Feature
###### Abstract  
The increase in the market for supersized LNG (liquefied natural gas) vessels, with double wall cargo tanks, has led to concerns regarding their safe operation. If both the primary and secondary wall of the cargo tank fail simultaneously, the hull of the vessel can be exposed to the LNG. This has the potential to cause brittle failure of the hull structure. This study presents a new acoustic emission (AE) technique approach that can be implemented for monitoring the structural condition of the cargo containment. The new technique approach is based on a feature of the AE waveform, calculated using quadratic Renyi's entropy. The presented technique is capable of providing information regarding critical damage so that appropriate maintenance can be carried out to avoid failure. The new AE technique is based on an AE feature that is independent of acquisition settings (e.g., threshold and timing), unlike many traditional AE features. The effectiveness of the proposed feature was evaluated by comparison with traditional AE features under ideal conditions for a range of varying acquisition settings. Unlike the traditional feature, the new feature demonstrated no variance with variation of the acquisition settings and was effective in capturing the collective information in the waveform. The proposed AE feature was validated through tensile and fatigue testing on standard specimens of austenitic stainless steel (material of the primary wall). The results suggest that the proposed AE feature is sensitive in identifying the critical damages irrespective of some data acquisition settings.  
acoustic emission; structural health monitoring; liquefied cargo containment +
Footnote †: journal: Applied Physics Letters
## 3 Model-Free Robust Control Design
### Adaptive PD RBFNN Controller Design  
A simple model-free realization of the system as a linear relationship between the input, i.e., voltage \(v\) applied to the linear actuator and output \(y\), i.e., linear displacement \(x\) of the link of mass \(m\) is considered. The input voltage is applied to the actuator and link_1 undergoes a linear displacement. There exist external disturbances \(d\) at the input and output of the system and uncertainties \(\Delta\) with bounds \((a\leq\|\Delta\|\leq b),\ a,b\in R^{n}\) or un-modeled dynamics that are part of the system. For the realized model, a Lyapunov-based adaptive PD controller was designed to achieve robust reference tracking. There is no information about the lumped function \(f_{1 pd}(x)\), which is essential for the controller design. An RBFNN was used to estimate the function and, using this function \(f_{1 pd}(x)\), the controller was designed. An adaptive PD RBFNN control loop is presented in Figure 7.  
The desired position is stated as \(y_{d}\) and the error \(e\) (error between the desired output and the current output) can be formulated as  
\[e=y_{d}-y=y_{d}-x_{mf_{1}} \tag{12}\]  
\[E=\left[\begin{array}{cc}e&\dot{e}\\ \end{array}\right]^{T}\]  
Using Equation (10), the control law for the feedback configuration is formulated as:  
\[\ddot{x}_{mf_{1}}=\alpha v+f_{1 pd}(x) \tag{13}\]  
\[\ddot{y}_{d}-\ddot{e}=\alpha v+f_{1 pd}(x)\]  
Using the intelligent PD control:  
\[\ddot{e}+kpe+k_{\mathrm{D}}\dot{e}=0 \tag{14}\]  
\[\ddot{e}=-K^{T}E\]  
Figure 7: Adaptive PD RBFNN controller.  
\[v^{*}=\frac{1}{\alpha}\Big{\{}-f_{lpd}(x)+\ddot{y}_{d}-\ddot{e}\Big{\}}\]  
\[v^{*}=\frac{1}{\alpha}\Big{\{}-f_{lpd}(x)+\ddot{y}_{d}+K^{T}E\Big{\}} \tag{15}\]  
where \(K^{T}=\left[\begin{array}{cc}k_{P}&k_{D}\end{array}\right]\).  
In Equation (14), \(f_{lpd}(x)\) is unknown, which is essential for the control law. \(f_{lpd}(x)\) is approximated using the NN and is used to realize the control law.
# Multifunctional Integrated Underwater Sound Absorption Materials: A Review
## 2 Underwater Acoustic Absorption Mechanisms and Research Advancements in This Area
### Research Advancements in Underwater Sound Absorption Materials
#### 2.2.1 Polymer-Based
The addition of surfactant decreased Young's modulus by 34% compared to pure PDMS, but this was an advantage because it helped to avoid acoustic impedance mismatch [32]. [PERSON], et al., found that a 3 mm thick layer of CNTs can provide up to 10%acoustic absorption within the frequency range from 0.125 kHz to 4 kHz [43]. [PERSON] investigated the underwater sound absorption of polyurethane elastomer in the frequency range from 2 kHz to 18 kHz, and found that it was affected by different molecular masses of polypropylene glycol [37]. [PERSON], [PERSON] et al., prepare graphene/SBR nanocomposites and its SEM images of graphene/SBR nanocomposites as shown in Figure 4d. The sample had a Young's modulus that was over 30 times higher than that of rubber. These nanocomposites exhibited excellent underwater sound absorption, with an average absorption coefficient of over 0.8 at 6-30 kHz. The absorption performance increased with increasing water pressure [44]. In deep water, high hydrostatic pressure causes the polymer's elastic modulus to increase, making it less effective at converting acoustic elastic energy, which leads to a reduction in the sound absorption coefficient. Additionally, polymers are susceptible to rotting in water and lack high-temperature resistance, which limits their practical applications.
## 2 Materials and Methods
### Analysis of Volatile Compounds by HS-SPME-GC-MS  
#### 2.4.1 HS-SPME-GC-MS Procedure  
The required amount of sample was weighed in a 20 mL amber vial. Then, 1 mL of deionised water and a polytetrafluoroethylene (PTFE) stirring rod were incorporated. The vial was then sealed with an aluminium crimp cap provided with a needle-pierceable polytetrafluoroethylene/silicone septum. The SPME fibre used was divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) 50/30 mm, StableFlex, 1 cm long, mounted to an SPME manual holder assembly (Supelco, Bellefonte, PA, USA). In the literature, this fibre was reported as suitable for the extraction of volatile compounds from raspberries [4]. The sample vial was placed in a water bath under temperature control and at 500 rpm stirring speed for 10 min for sample equilibration. The SPME needle was inserted into the vial through the septum, and the fibre was exposed to the vial headspace. After the required extraction time, the fibre was immediately desorbed into the GC-MS injection port at 250 \({}^{\circ}\)C for 10 min (splitless mode) on an Agilent 6890N GC coupled to a 5973N MS (Agilent Technologies, Palo Alto, CA, USA) operating in electron ionisation mode (EI 70 eV). The ion source and GC-MS transfer line temperatures were 230 and 280 \({}^{\circ}\)C, respectively. A DB-624 column, 30 m \(\times\) 0.25 mm \(\times\) 0.14 mm (Agilent Technologies, Palo Alto, CA, USA), was used, and it was programmed to change from 50 (hold, 2 min) to 250 \({}^{\circ}\)C at a rate of 10 \({}^{\circ}\)C min\({}^{-1}\) (hold 12 min). Helium was used as the carrier gas (1 mL min\({}^{-1}\)). Blank runs were carried out before sample analysis to verify a lack of contaminants on the fibre. Peak identification was based on the comparison of mass spectrum data with spectra in full scan mode (_m/z_ 30-550) present in the Wiley library, considering the volatile compounds that had equal to or more than 90% similarity. In this study, six raspberry volatile markers were selected: linalool, \(\alpha\)-ionone, \(\beta\)-ionone, hexanal, decanal and nonanal. All of them were quantified using calibration curves at six concentration levels prepared in deionised water. All determinations were carried out in triplicate.
# Weed Detection in Rice Fields Using Remote Sensing Technique: A Review
## 3 The Importance of Rice Productivity
However, to achieve rice production sustainably and meet demands, productivity and quality must significantly improve. Therefore, through participatory approaches, it is critical to foster joint working between research, extension, local governments, non-governmental organizations (NGO), and private industry to identify the relevant constraints to high yield, adopt new solutions and technologies, and make systematic decisions to close rice yield gaps.
# Iterated Orthogonal Simplex Cubature Kalman Filter and Its Applications in Target Tracking
## 5 Simulations and Results
### Spacecraft Target Tracking Simulation
#### 5.2.2 Ground Radar Measurement Model
In order to obtain the relationship between the measured value and the orbit state, we write \(\mathbf{X}_{h}\) and \(\dot{\mathbf{X}}_{h}\) in the form of a specific vector as \(\mathbf{X}_{h}=\left(x_{h}\quad y_{h}\quad z_{h}\right)^{\text{T}}\) and \(\dot{\mathbf{X}}_{h}=\left(\dot{x}_{h}\quad\dot{y}_{h}\quad\dot{z}_{h}\right)^{ \text{T}}\); then, the geometric relationship between the radar ranging value \(R\), velocity measurement value \(\dot{R}\), azimuth angle \(A\), and pitch angle \(E\) and the orbit state is as follows:  
\[\left\{ \begin{aligned} R&=\sqrt{x_{h}^{2}+y_{h}^{2}+z_{h}^ {2}}\\ A&=\arctan\frac{y_{h}}{x_{h}}\\ E&=\arctan\frac{z_{h}}{\sqrt{x_{h}^{2}+y_{h}^{2}}} \end{aligned} \right. \tag{51}\]  
Equation (46) can be written as the following discrete measurement equation:  
\[\mathbf{Z}_{k}=\mathbf{h}(\mathbf{X}_{k})+\mathbf{v}_{k} \tag{52}\]  
where \(\mathbf{Z}_{k}=\left(R_{k}\quad A_{k}\quad E_{k}\right)^{\text{T}}\) is the measured value at time \(k\), and \(\mathbf{v}_{k}\) is the measured noise. Thus, Equations (35) and (47) constitute the state equation and measurement equation corresponding to Equation (11) for real-time filtering orbit determination.