esa-sceva/satcom-chunk-collection huggingface dataset:
## 3 Full-Scale Model Test
### Test Results  
#### 3.2.1 Impulse Hammer Test  
Figure 5 shows the example of the time-history waveform of the excitation force and the vertical acceleration measured by the accelerometer embedded in the ballast. The vibration was attenuated after it was excited to the ballast by the hammer, and it converged in about 0.05 s. The waveform was disordered and not a typical free vibration waveform. This was thought to be because the damping of the ballast itself was larger than that of concrete or steel members and that the ballast was a discrete body rather than a vibration of a continuous body such as a beam [19].  
Figure 6 shows the comparison of the accelerance. From the figure, the ballasted ladder track had smaller acceleration in a wide-frequency band except for around 80 to 100 Hz. The influence of the bending vibration mode of the ladder sleepers described later was the reason why the reduction effect of the ballasted ladder track was not seen at 80 to 100 Hz.  
Figure 7 shows the identification results of the natural frequency and vibration mode shape of ladder sleepers. In these vibration mode types, accelerometers were arranged at multiple points and acquired by modal analysis. The natural frequency of the ladder sleepers' bending first mode was 79 Hz, the second mode was 151 Hz, the third mode was 293 Hz, the fourth mode was 480 Hz, and the fifth mode was 748 Hz. The figure also  
Figure 5: Example of the time-history waveform of the excitation force and the acceleration in the ballast (ballasted ladder track): (**a**) excitation force; (**b**) vertical acceleration measured in the ballast.  
Figure 6: Comparison of the accelerance.  
depicts the natural frequencies obtained by the numerical analysis model described later. From the figure, the natural frequency could be represented with an error of about 10% or less. According to previous research [19], the natural frequency of the bending first vibration mode of the PC sleepers compared this time is 158 Hz, the second mode is 440 Hz, and the third mode is 850 Hz. It was found that the vibration characteristics of the sleepers differed greatly.
# Hardware Acceleration of Tsunami Wave Propagation Modeling in the Southern Part of Japan
## 2 Data and Methods
### MacCormack Scheme  
The two half-step MacCormack scheme (see [11]) was used for numerical approximation of the shallow water system (1). This algorithm is an explicit difference scheme which uses the three-point stencil of a \"cross\" type. The calculation at each time iteration is arranged in two steps. Each turn, the values of wave height and components of the velocity vector are computed using the necessary data at the same point and two adjacent points of the grid at the previous time value; see [12; 13; 14] for the calculation stencil description. Below is the version of the MacCormack scheme we used for numerical experiments.  
\[\frac{\widetilde{H}_{ij}^{n+1}-H_{ij}^{n}}{\tau}+\frac{H_{ij}^{n}u_{ij}^{n}-H_ {i-1j}^{n}u_{i-1j}^{n}}{\Delta x}+\frac{H_{ij}^{n}v_{ij}^{n}-H_{ij-1}^{n}v_{ ij-1}^{n}}{\Delta y}\ =  
\[\frac{v_{ij}^{n+1}-\left(\widetilde{v}_{ij}^{n+1}+v_{ij}^{n}\right)/2}{\tau/2}+u_{ ij}^{n}\frac{\widetilde{v}_{i+1}^{n+1}-\widetilde{v}_{ij}^{n+1}}{\Delta x}+v_{ij}^{n} \frac{\widetilde{v}_{ij+1}^{n+1}-\widetilde{v}_{ij}^{n+1}}{\Delta y}+g\frac{ \widetilde{\eta}_{ij+1}^{n+1}-\widetilde{\eta}_{ij}^{n+1}}{\Delta y}\ =\ 0\]  
Here, \(H_{ij^{\prime}}^{n}\), \(u_{ij^{\prime}}^{n}\) and \(v_{ij}^{n}\) are the gridded variables which correspond to the \(H\), \(u\), and \(v\) functions in differential system (1). The parameters \(\tau\), \(\Delta x\), and \(\Delta y\) are the time step and spatial steps of the computational grid. In order to account for the spherical shape of the Earth, we use a decreasing grid step with respect to longitude for larger values of latitude. The notation \(F_{ij}^{n}\) represents variables at time layer \(n\), \(\widetilde{F}_{ij}^{n+1}\) represents intermediate values, and \(F_{ij}^{n+1}\) corresponds to the variables at time layer \(n+1\).  
Our implementation of the MacCormack scheme was previously numerically tested against the available analytical solutions of shallow water ray approximation for the cases of model-type bottom topographies; see [15]. In the littoral areas that are considered in the referenced paper, the size of the computation domain is \(1000\times 1000\) km in both cases. In the first case, the depth linearly increases according to the formula \(D(x,y)=0.01y\). In the second case of parabolic bottom topography, the depth increases according to the formula \(D(x,y)=10^{-8}\cdot y^{2}\), where \(y\) stands for the offshore distance. In Figure 1 we present a comparison of the shallow water system solutions obtained by our FPGA-based \"Calculator\" and by MOST software with the exact solution in the case of sloping bottom topography (where depth linearly increases along the ordinate axis). The wave is initiated by rounded water surface elevation with radius equal to 50 km and height limited to 2 m. Its center is situated 300 km off the shore. As can be observed in Figure 1 (cf. [12]), the similarity is rather good, while the proposed scheme is better in terms of wave front simulation when compared to MOST software.
###### Abstract  
Tight sandstone reservoirs, despite their low porosity and permeability, present considerable exploration potential as unconventional hydrocarbon resources. Natural fractures play a crucial role in hydrocarbon migration, accumulation, and present engineering challenges such as late-stage reformation in these reservoirs. This study examines fractures in the seventh member of the Triassic Yanchang Formation's tight sandstone within the Ordos Basin using a range of methods, including field outcrops, core samples, imaging and conventional logging, thin sections, and scanning electron microscopy. The study clarifies the characteristics of fracture development and evaluates the relationship between dynamic and static rock mechanics parameters, including the calculation of the brittleness index. Primary factors influencing fracture development were quantitatively assessed through a combination of outcrop, core, and mechanical test data. Findings reveal that high-angle structural fractures are predominant, with some bedding and diagenetic fractures also present. Acoustic, spontaneous potential, and caliper logging, in conjunction with imaging data, enabled the development of a comprehensive probabilistic index for fracture identification, which produced favorable results. The analysis identifies four key factors influencing fracture development: stratum thickness, brittleness index, lithology, and rock mechanical stratigraphy. Among these factors, stratum thickness is negatively correlated with fracture development. Conversely, the brittleness index positively correlates with fracture development and significantly influences fracture length, aperture, and linear density. Fractures are most prevalent in siltstone and fine sandstone, with minimal development in mudstone. Different rock mechanics layer types also impact fracture development. These insights into fracture characteristics and controlling factors are anticipated to enhance exploration efforts and contribute to the study of similar unconventional reservoirs.  
tight sandstone reservoirs; fracture identification; main controlling factors; Ordos Basin; Yanchang Formation +
Footnote †: journal: Applied Sciences
# A Trust-Influenced Smart Grid: A Survey and a Proposal
## 7 Multi-Agent Systems (MASs)  
A multi-agent system (MAS) is a system consisting of two or more intelligent agents [58]. An intelligent agent is described as an entity with four characteristics, namely social ability, reactivity, pro-activeness, and autonomy. Social ability requires that the agent should be able to interact with other agents. This is often mistaken as just the exchange of messages. However, it requires the ability to cooperatively interact and negotiate or in simple terms; agents should be able to converse. Reactivity requires that when there are changes to the environment in which the agent is in, the agent must react promptly; and based on its goals and those changes, the agent must take some appropriate action. Pro-activeness requires that the agent must change its dynamically behaviour to achieve its goals. Autonomy requires that agents must operate without any intervention from humans or any external system.  
An MAS has an overall objective or goal to which each agent's goals within the MAS must contribute to the achievement of that overall objective. There are three kinds of MAS architectures, namely centralized, decentralized, and hybrid. Centralized architecture has agents reporting to a central agent from whom the agents await instructions. Decentralized architecture has agents communicating with each other in a clustered manner, with each having the same level of priority. In the case of centralized architecture, the demise of the central agent spells the demise of the MAS. The optimization of MAS goals is challenging with a decentralized architecture because of the local nature of the connection between agents. The hybrid architecture combines the two previous architectures to utilize their advantages.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline  & & **Trust Components** & & \\ \hline
**Direct Trust** & **Indirect Trust** & \
\begin{tabular}{c} **Tested Against** \\ **Trust Attacks** \\ \end{tabular} & **Risk Component** &
\begin{tabular}{c} **Knowledge** \\ **Component** \\ \end{tabular} \\ \hline
[52, 53, 54, 55] & [52, 53] & - & - & [56, 57] \\ \hline \hline \end{tabular}
\end{table}
Table 4: Research on trust in substation categorized by trust components.  
MAS has been implemented in microgrids [59], demand side management [60], smart meters [61], optimal power flow and energy-sharing [62], and Smart Grid simulation [63].
## 5 Experiments and Results
### Validating Tests
#### 5.5.1 Validating Tests in the MPE Environment
In order to mitigate the impact of the MPE environment, we reduce the value of \(\lambda_{I}\) and run testing experiments in MPE\(-\)LS\(-\)V2. The results of value-based and policy-based algorithms are shown in Figures 12 and 13, respectively. Generally, reducing \(\lambda_{I}\) to release the limitation of CGP loss helps to improve the performance of G-QMIX and G-MAPPO. In Figure 12b, G-QMIX acquires a higher result than QMIX baseline with higher variance. In Figure 13b, G-MAPPO performs better than MAPPO with higher mean value and smaller variance. In summary, when conducting the GAPO methods in different heterogeneous cooperative MARL scenarios, it is highly necessary to carefully analyze the properties of the scenario and conduct pre-experiments to determine the optimal value of \(\lambda_{I}\). Figure 11: Results for MPE validating tests using policy-based algorithms. Figure 10: Results for MPE validating tests using value-based algorithms.
## 2 Materials and Methods
### Statistical Analysis  
Statistical analyses were conducted using Jamovi software (version 2.3.11; Jamovi Project, Sydney, Australia). All parametric values are reported as mean \(\pm\) standard deviation (SD). The Wilcoxon signed rank test was used to compare the CVR values across SPECT, tcMRI, and MRI. The top 30% of regions based on SPECT CVR values were selected, and corresponding CVR values were extracted from tcMRI and MRI. This approach focused the regional comparison on areas exhibiting the most robust CVR as measured by the established SPECT technique, providing a basis to assess the agreement and differences in the novel MRI-based methods specifically in regions with significant perfusion responses [16; 25]. Repeated measures analysis of variance was used to assess significant differences in CVR values across techniques (SPECT, tcMRI, and MRI) in these selected regions. Where significant differences were found, post hoc comparisons were performed using [PERSON]'s test. The standard criterion of statistical significance (\(p<0.05\)) was applied to all analyses.  
Figure 4: Illustration of the single photon emission computed tomography (SPECT) one-day protocol for brain imaging.
# A Study on Analyzing Travel Characteristics of Micro Electric Vehicles by Using GPS Data
## 2 Literature Review
### Research on Travel Behavior  
[PERSON] classified nine categories of tours by considering the combination of primary and complex tours and three different activity goals within each tour [23]. [PERSON] and his colleagues categorized all trips into three different categories according to their primary purpose. Nevertheless, the analysis of travel patterns based on tour or trip chains has mainly focused on developed countries, neglecting to examine the connections between urban structure and trip chaining behavior [24].  
[PERSON] and their research team conducted a study that aimed to analyze how individuals combine their stops in their travel routines, with a focus on workers and their non-work-related activities. The theoretical findings indicated that factors like the speed of travel, distance of commuting, cost of transportation, and density of areas had an impact on how people plan their trips. The empirical evidence from two regions and time periods supported these correlations. Interestingly, despite the stability in trip rates, the research observed changes in trip chaining behavior over time. For example, there was an increase in the number of office-based work activities being performed on foot between 1970 and 1980 [25].  
[PERSON] and [PERSON] examined whether the trip plan was influenced by the layout of areas. Specifically, it focused on whether areas with population density tend to have frequent instances of combining multiple trips into one and having more complex travel routes. By analyzing data from the \"2001 National Household Travel Survey\", the study identified factors that influenced people's tendency to combine trips into intricate tours with multiple stops. The results showed that when considering factors like household characteristics and traveler traits, areas with lower population density tend to rely more on trip chaining and have more stops in their travel tours [26].  
[PERSON] and [PERSON] explored the trip behavior of commercial vehicles, looking at their day-to-day travel. It was observed that these vehicles completed around 5.6 tasks each day, with trip chains being common. About one out of every four was involved in several trip chains on a given day. An interesting find was that the more tasks in a trip chain, the less trip chains a vehicle made in a day. Freight or goods being transported were the main reason for these trips. This was true even with vehicles which were normally considered as people carriers, not goods carriers. A noteworthy finding was that more valuable freight added to the length of a trip chain. The study urged more research to better comprehend the ins and outs of trip chains and the behaviors tied to them [27]. The FHWA study showed that 27% of people working during the week engaged in trip chaining in 2001. As presented by [PERSON] and their research team, this behavior offered potential for Transportation Demand Management (TDM) programs. People who chained trips often lived far from their jobs and drove more miles in a year [28].
# PAPR Reduction in UFMC for 5G Cellular Systems
## 2 The UFMC System Model
### UFMC Receiver  
When considering perfect frequency synchronization, the signal \(\mathbf{y}\in\mathbb{C}^{N+L_{f}-1\times 1}\) at the receiver side after CP removal and zero forcing channel equalization will be given as:  
\[\mathbf{y}=\mathbf{\tilde{D}}^{H}\mathbf{H}^{-1}\mathbf{H}\mathbf{x}+\mathbf{ \tilde{D}}^{H}\mathbf{n} \tag{6}\]  
where \(\mathbf{H}\in\mathbb{C}^{(N+L_{cp}+L_{f}-1)\times(N+L_{cp}+L_{f}-1)}\) is the equivalent channel convolution matrix of \(h(t)\) that follows the Rayleigh fading distribution, and \(\mathbf{n}\in\mathbb{C}^{(N+L_{cp}+L_{f}-1)\times 1}\) is a zero mean AWGN with variance \(\sigma^{2}\) at the receiver. The demodulation matrix \(\mathbf{\tilde{D}}\) is given as \(\mathbf{\tilde{D}}=[\mathbf{0}:\mathbf{D}]\in\mathbb{C}^{N+L_{f}-1\times(N+L _{cp}+L_{f}-1)}\), where \(\mathbf{0}\in\mathbb{C}^{N+L_{f}-1\times L_{cp}}\) denotes the zero matrix CP removal and \(\mathbf{D}\in\mathbb{C}^{(N+L_{f}-1)\times(N+L_{f}-1)}\) denotes the FFT matrix.  
Subsequently, the output signal \(\mathbf{y}\) is zero padded with \(N-L_{f}+1\) zeros to avoid ISI. Afterwards, \(2N\)-point FFT is used to obtain the received sequence, where only the even index samples of the total \(2N\) complex samples are taken and the odd indices are discarded. Finally, the output passes through frequency domain equalization to detect the transmitted symbols \(\mathbf{\tilde{S}}\) and the symbol de-mapping demodulates the output signal from the equalized signal to restore the estimated bit sequence.
# Cooperative Buffering Schemes for Time-Shifted Live Streaming of Distributed Appliances
## 3 Cooperative Buffering Schemes for Time-Shifted Live Streaming
### Computational Complexity
It is also noted that our proposed schemes can further achieve the computation offloading of PVRs by removing the exchange of the keep-alive messages between PVRs, instead maintaining the aggregate buffermap to verify if each PVR is still participating in the network.
## 4 Evaluation Proposal and Analysis
### Discussion
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & & & \begin{tabular}{c} **Energy** \\ **Consumption** \\ **(mW)** \\ \end{tabular} & \begin{tabular}{c} **Energy** \\ **Consumption** \\ **(mW)** \\ \end{tabular} & \begin{tabular}{c} **Energy** \\ **Consumption** \\ **(mW)** \\ \end{tabular} \\ \hline \begin{tabular}{c} **Number** \\ **of Nodes** \\ \end{tabular} & \begin{tabular}{c} **Disconnected** \\ **Nodes (\%)** \\ \end{tabular} & \
\begin{tabular}{c} **Transmission/** \\ **Interference** \\ \end{tabular} & **ETX** & **HOP** &
\begin{tabular}{c} **Transmission/** \\ **Interference** \\ \end{tabular} & **ETX** & **HOP** \\ \hline \multirow{3}{*}{10} & 0 & & 1.2124 & 1.1705 & & 1.1744 & 1.0915 \\  & 10 & 50/100 m & 1.2842 & 1.2812 & 70/90 m & 1.2697 & 1.1806 \\  & 20 & & 1.4484 & 1.2248 & & 1.2868 & 1.1899 \\ \hline \multirow{3}{*}{20} & 0 & & 1.5482 & 1.3864 & & 1.2977 & 1.2575 \\  & 10 & & 2.1861 & 1.5578 & & 1.4724 & 1.4210 \\  & 20 & & 2.2158 & 1.4922 & & 1.5615 & 1.4058 \\  & 30 & & 1.9948 & 1.4259 & & 1.6700 & 1.3994 \\ \hline \multirow{3}{*}{30} & 0 & & 2.3544 & 1.5900 & & 1.4585 & 1.3630 \\  & 10 & & 2.3837 & 1.8175 & & 1.5898 & 1.4666 \\ \cline{1-1}  & 20 & & 2.4808 & 1.7541 & 70/90 m & 1.6330 & 1.4277 \\ \cline{1-1}  & 40 & & 2.5662 & 1.7010 & & 1.6993 & 1.3954 \\ \cline{1-1}  & 50 & & 2.5825 & 1.6530 & & 1.7517 & 1.4167 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Energy consumption in the grid topology. evaluated with the grid topology. Likewise, comparisons were made only with the HOP metric. The results were from six different scenarios, and the circular topology was better in all scenarios. Regarding the three topologies evaluated, it could be concluded that a circular topology resulted in better performance concerning maintaining the number of nodes. The tree topology required considerably more of the first hop node and could also cause other bottlenecks in the network. The node density was critical in tree topology and needed to be carefully evaluated before being adopted in an IoT with RPL. In Figure 20, it can be seen that in general, the topologies with the 50/100 transmission/ interference range had higher energy consumption than the scenarios performed with the 70/90 m transmission/interference range. Furthermore, the circular topology had the lowest energy consumption, followed by the grid topology, and finally, the tree topology obtained the highest energy consumption. Therefore, it was clear that the circular topology was the best compared to the other topologies in the disconnected node scenarios with a high level of confidence.
# A Compact, Low-Profile, Broadband Quasi-Isotropic Antenna for Non-Line-of-Sight Communications
###### Abstract  
A single-feed broadband quasi-isotropic antenna was designed for non-line-of-sight (NLOS) wireless sensor networks. The proposed antenna is based on a combination of fork-shaped crossed dipoles. It shows the broadband of quasi-isotropic radiation characteristics with high radiation efficiency. The electrical size \(ka\) of the proposed antenna is 0.94 with respect to its lower operating frequency. Its profile is also extremely thin at 0.0015\(\lambda\). The impedance is matched from 1.8 to 4.3 GHz, or an 81.9% fractional bandwidth, whereas the maximum gain deviation ranging from 6.2 to 9.2 dB for the quasi-isotropic radiation is achieved from 1.8 to 3.6 GHz with a 10 dB criterion, which is close to the impedance bandwidth. The performance from the computed expectations is verified, as it shows a gain deviation of 8.4-9.8 dB from 1.9 to 3.3 GHz with an 80% fractional impedance bandwidth. The proposed antenna also shows good spatial coverage of circular polarization at high frequencies. Lastly, the received power level performance of the proposed antenna is tested under the NLOS condition, which shows a higher level compared to the linearly polarized, broadband omni-directional monopole antenna.  
broadband antennas; crossed dipole; isotropic radiation; non-line-of-sight communications; pattern synthesis; small antennas; wireless sensor networks +
Footnote †: journal: Applied Sciences  
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Footnote †: journal: Applied Sciences  
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Footnote 0: _Applied Sciences_