esa-sceva/satcom-chunk-collection huggingface dataset:
# Fluid Net Models: From Behavioral Properties to Structural Objects
## 2 Basic Concepts and Notations
### Timed Continuous Petri Net Systems
An _operation mode_ or _regime_\(\boldsymbol{\Sigma}_{\mathcal{C}}\) of a TCPN system is the linear system (\(\dot{\boldsymbol{m}}=\boldsymbol{CA\Pi_{\mathcal{C}}}\boldsymbol{m}\), where \(\boldsymbol{\Lambda}=diag(\boldsymbol{\lambda})\) is a diagonal matrix) which describes the marking evolution, while \(\boldsymbol{m}\) evolves within region \(\mathcal{R}_{\mathcal{C}}\). At configuration \(\mathcal{C}\), \(\boldsymbol{CA\Pi_{\mathcal{C}}}\) is the _dynamic matrix_. The set of all configurations of a net \(N\) is represented as \(\mathcal{SC}(N)\), its number being bounded by \(\Pi_{i}|^{\bullet}t_{i}|\). Therefore, a net may contain an exponential number of configurations. As a notation, \(\mathcal{C}_{t_{1},\;\ldots,\;t_{|T|}}\) is a configuration where \((p_{i_{k}},t_{k})\in\mathcal{C}_{t_{1},\;\ldots,\;i_{|T|}}\). Figure 0(b) has \(\Pi_{i}|^{\bullet}t_{i}|=2\times 2\times 2\times 2\times 2\times 2\times 1=64\) different configurations. In Figure 4, we are depicting the induced subnets by four of them. The dynamic behavior of a TCPN system can be described by the following equations:  
\[ \begin{split}\dot{\boldsymbol{m}}=\boldsymbol{CA\Pi_{\mathcal{C }}}\boldsymbol{m},\quad\boldsymbol{m}\in\mathcal{R}_{\mathcal{C}},\quad \mathcal{C}\in\mathcal{SC}(N)\\ \boldsymbol{m}(0)=\boldsymbol{m}_{0}.\end{split}  \tag{6}\]  
Configurations and T-covertures are sets related with the structure of the net \(N\). Both structural objects allow to address some analysis of the system and are key for the results presented in upcoming sections. They are also related to the regions of the CPN system \(\langle N,\boldsymbol{m}_{0}\rangle\) and to the operation modes of the TCPN system \(\langle N,\boldsymbol{\lambda},\boldsymbol{m}_{0}\rangle\). An _equilibrium marking_\(\boldsymbol{m}_{e}\in\mathcal{R}_{\mathcal{C}}\) is a state of the TCPN system fulfilling \(\dot{\boldsymbol{m}}=\boldsymbol{CA\Pi_{\mathcal{C}}}\boldsymbol{m}_{e}= \boldsymbol{0}\); its corresponding _equilibrium throughput_ is denoted by \(\boldsymbol{f}_{e}=\boldsymbol{\Lambda\Pi_{\mathcal{C}}}\boldsymbol{m}_{e}\). Figure 4: Induced nets associated with 4 of the 64 configurations of the net depicted in Figure 0(b). Note that \(\mathbf{\Lambda}\geq\mathbf{0}\), \(\mathbf{\Pi}_{C}\geq\mathbf{0}\) and \(\mathbf{m}_{e}\geq\mathbf{0}\), and thus, \(\mathbf{f}_{e}\geq\mathbf{0}\), and it is a non-negative linear combination of the T-semiflows of the net, no matter which configuration is activated by \(\mathbf{m}_{e}\).
# Effect of Adding Waste Polyethylene and GGBFS on the Engineering Properties of Cement Mortar
## 3 Results and Discussions
### Water Absorption Ratio  
As shown in Figure 10, when the W/B was 0.5 on the 28 th day, with no added GGBFS and 0%, 1%, 2%, 3%, and 4% waste PE added to the cement mortar sample, the water absorptions were 10%, 10.3%, 10.6%, 11.1%, and 11.6%, respectively. This result indicated that when the added volume of waste PE increased, the sample generated more holes, which increased the internal holes of the sample and water absorption.  
After 28 days, when adding 10% GGBFS to replace the cement, the water absorption was 10.2% to 10.9%; when 20% GGBFS was added, the water absorption was 8.7% to 10.5%. If the replaced volume of GGBFS increased, hydration in the early phase was slow, which made the water absorption of the sample higher than that of the control group. However, the hydrates produced by the pozzolanic reaction of GGBFS filled the pores of the samples and made the mortar structure dense. In the late period, when the replaced volume of GGBFS was higher, the decline in water absorption was more prominent. This result indicated that GGBFS could increase the sample's internal compactness and decrease permeability, and the durability could be higher. The group with 20% GGBFS had lower water absorption, good compactness, and higher durability.  
Figure 9: The ultrasonic velocity of cement mortars with the addition of different ratios of waste PE and GGBFS replacement.
## 4 Experimental Results of Active Localization in a Reverberant Environment
### Localization Performance in a Reverberant Environment
\begin{table}
\begin{tabular}{c c c c c} \hline \hline  & \multicolumn{2}{c}{**PVC Pipe**} & \multicolumn{2}{c}{**Person**} \\ \hline
**Position** & **Anechoic** & **Classroom** & **Anechoic** & **Classroom** \\ \hline \multirow{4}{*}{\(\text{A}^{1}_{135}\)} & \(\Delta\Theta=0^{\circ}\) & \(\Delta\Theta=0^{\circ}\) & \(\Delta\Theta=0^{\circ}\) & \(\Delta\Theta=0^{\circ}\) \\  & \(\Delta\pi=0.04\) m & \(\Delta\pi=0.06\) m & \(\Delta\pi=0.03\) m & \(\Delta\pi=0.11\) m \\  & (4\%) & (6\%) & (3\%) & (11\%) \\ \hline \multirow{4}{*}{\(\text{B}^{1.5}_{90}\)} & \(\Delta\Theta=0^{\circ}\) & \(\Delta\Theta=0^{\circ}\) & \(\Delta\Theta=0^{\circ}\) & \(\Delta\Theta=0^{\circ}\) \\  & \(\Delta\pi=0.02\) m & \(\Delta\pi=0.03\) m & \(\Delta\pi=0.09\) m & \(\Delta\pi=0.51\) m \\  & (1.33\%) & (2\%) & (6\%) & (34\%) \\ \hline \multirow{4}{*}{\(\text{C}^{2}_{90}\)} & \(\Delta\Theta=0^{\circ}\) & \(\Delta\Theta=0^{\circ}\) & \(\Delta\Theta=5^{\circ}\) & \(\Delta\Theta=5^{\circ}\) \\  & \(\Delta\pi=0.03\) m & \(\Delta\pi=0.13\) m & \(\Delta\pi=0.05\) m & \(\Delta\pi=0.43\) m \\  & (1.5\%) & (6.5\%) & (2.5\%) & (21.5\%) \\ \hline \multirow{4}{*}{\(\text{D}^{2.5}_{75}\)} & \(\Delta\Theta=0^{\circ}\) & \(\Delta\Theta=0^{\circ}\) & \(\Delta\Theta=0^{\circ}\) & \(\Delta\Theta=0^{\circ}\) \\  & \(\Delta\pi=0.01\) m & \(\Delta\pi=0.04\) m & \(\Delta\pi=0.13\) m & \(\Delta\pi=0.27\) m \\ \cline{1-1}  & (0.4\%) & (1.6\%) & (5.2\%) & (10.8\%) \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Position errors of a PVC pipe and a person in terms of localization performance. The data of the anechoic chamber indicated the initial error of the proposed method under the condition that no effect of reflection and reverberation occurred in the control space, and the data of the classroom indicated the performance of the proposed method under conditions of reflection and reverberation. In an anechoic environment that represented the initial error, the position error increased in the scenario of a person compared with that of a PVC pipe. This was caused by the slight movement of the person, and the data results in Table 4 indicate that the position error can be further increased when this movement is combined with a reverberation environment. From the experimental results of Case 2 in a classroom, we confirmed that the results of the PVC pipe had a small error, within 6.5%, owing to the nonmovement of a pipe, whereas the cases of a human intruder indicated a relatively large error, within 5\({}^{\circ}\) of the estimated angle and 34% of the estimated distance. Therefore, the above results of localization performance improve the limitations of the existing acoustic-based security system, for which an intruder must generate sound. Moreover, the proposed method estimates the x and y positions using a linear microphone array in a two-dimensional security space.
# A Novel 4 \(\times\) 1 MISO-VLC System with FBMC-OQAM Downlink Signals
###### Abstract  
A novel visible-light communication (VLC) system with \(4\times 1\) multi-input-single-output (MISO) channels is designed. In the system, the filter bank multicarrier (FBMC) and offset quadrature amplitude modulation (OQAM) techniques are used to generate downlink signals. The principles and implementation methods are proposed and analyzed, and the light intensity and received light power distribution of four LED emitters are discussed. The results demonstrate that it not only satisfies the requirements of indoor information access but also provides daily lighting. The used FBMC-OQAM signals exhibit better reception performance than orthogonal frequency division multiplexing (OFDM) signals. The system used has a lower bit error rate (BER) and larger access bandwidth compared to a \(1\times 1\) single-input-single-output (SISO) system. It has the potential for application advantages in future indoor VLC system applications.  
optical communication system; filter bank multicarrier; multi-input-single output; visible-light communication; bit error rate +
Footnote †: journal: _Photonics_  
_et al._ Article_  
**Citation:** [PERSON]; [PERSON]; [PERSON]; [PERSON] [PERSON]; [PERSON]; [PERSON]; [PERSON]; [PERSON]; [PERSON] [PERSON] A Novel 4 \(\times\) 1 MISO-VLC System with FBMC-OQAM Downlink Signals. _Proceedings_**2024**, _11_, 415. [[https://doi.org/10.3300/photonics1105045](https://doi.org/10.3300/photonics1105045)]([https://doi.org/10.3300/photonics1105045](https://doi.org/10.3300/photonics1105045))  
Received: 5 April 2024  
Received: 18 April 2024  
Accepted: 28 April 2024  
Published: 30 April 2024  
**Copyright**\(\copy\) 2024 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license ([[https://creativecommons.org/licenses/by/4.0/](https://creativecommons.org/licenses/by/4.0/)]([https://creativecommons.org/licenses/by/4.0/](https://creativecommons.org/licenses/by/4.0/))).  
**Appendix**\(\copy\) 2024 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license ([[https://creativecommons.org/licenses/by/4.0/](https://creativecommons.org/licenses/by/4.0/)]([https://creativecommons.org/licenses/by/4.0/](https://creativecommons.org/licenses/by/4.0/))).
## 2 Case Study  
The theatre of Syracusae (SR) was chosen as case study for a measurement campaign carried out by the Department of Energy at the Politecnico di Torino, from the 5 th to 7 th September 2015. SR (Figure 1) has Greek origins, dating back to the 5 th century BC, but it was later modified by the Romans. Apart from a few ruins, nothing is visible of the original scenae frons, but the surviving part of the rock-cut cavea has a diameter of 105 m.  
Several studies that refer to the acoustics of SR have been retrieved from literature. These studies refer to measurements on a scale model of the ancient theatre and its contemporary use [4; 24], to acoustic and lighting simulations [25], and to in situ acoustical characterisations with temporary scenery [26]. Measurements had only been carried out in empty conditions at one point of the orchestra area, as a pilot study in which different techniques were used [27].  
This ancient open-air theatre is intensively used during cyclic summer season festivals in its current (deteriorated) condition, and acoustic measurements are made also for conservation purposes. Therefore, this study concerns the \"historical acoustics\" research field, which is the study of the auditory and acoustic environment of historic sites and monuments [1], with a valorisation purpose. The empty condition has been chosen for obvious practical reasons, as with the public present it is very difficult to carry out reliable measurements due to high background noise levels and unsteady boundary conditions [28]. Moreover, in order to simulate correctly the presence of public or the placement of an acoustic shell for renovation purposes, the reliability of simulated data must be verified, starting from the calibration of the acoustic model.
## 2 Nanofluid Thermal Conductivity
### Effects of Concentration of Nanoparticles on Nanofluid Thermal Conductivity  
In general, experimental data has shown that nanofluid thermal conductivity increases with nanoparticle volume fraction [1; 3; 4; 7; 8; 9; 10; 11; 13; 15; 16; 22; 23; 24; 25; 26; 27; 28; 29; 30]. However, in some cases researchers have observed a linear relationship between thermal conductivity and nanoparticle concentration [3; 9; 15; 22; 37; 38; 39; 40], whereas in other cases a non-linear relationship has been observed [1; 4; 7; 8; 11; 13; 16; 23; 26; 27; 28; 29; 30; 31; 32; 33; 34; 35; 36]. Using the transient line heat source method, [PERSON] et al. [10] measured the thermal conductivities of CuO-water, CuO-Ethylene Glycol, and CuO-engine oil nanofluids. For all nanofluids tested, the thermal conductivity increased with concentration. It was suggested that this relationship was a result of increased available surface area for heat transfer at higher nanoparticle concentrations. Using the transient hot-wire method, [PERSON] et al. [24] studied the thermal conductivity of Al\({}_{2}\)O\({}_{3}\)-water nanofluid containing brick, platelet and blade nanoparticles. For all nanoparticle shapes, the thermal conductivity increased with the increase of nanoparticle concentration. [PERSON] et al. [25] measured the thermal conductivity of TiO\({}_{2}\)-water nanofluid as a function of nanoparticle volume concentration using nanoparticles of irregular shape with the same average size. It was observed that the thermal conductivity increased with particle concentration. It was suggested that nanoparticle concentration had a more significant effect on thermal conductivity than particle shape and size. In many experiments, a non-linear relationship between the concentration of nanoparticles and nanofluid thermal conductivity has been observed, which is likely due to greater agglomeration at higher nanoparticle concentrations. [PERSON] et al. [26] measured the thermal conductivity of MgO-Ethylene Glycol nanofluid as a function of nanoparticle concentration. It was observed that at concentrations below \(\varphi=1\%\), change in thermal conductivity for the nanofluid was more rapid than at higher concentrations. This result was attributed to increased particle agglomeration at higher concentrations. Using the
# Review of V2X-IoT Standards and Frameworks for ITS Applications
## 2 Core ITS Standards
### Standards for 4G- and 5G-Based Cellular (C-V2X) Technology
Although C-V2X has many advantages that stem from reusing an already developed network infrastructure, its downsides must also be considered. A high number of intermediary nodes for Uu sidelinks means an increase in transmission delays. Message re-transmission is supported by 3 GPP standards and intermediary nodes re-transmit messages to all devices in range. Retransmissions puts unnecessary network traffic load on networking equipment, while the retransmission decision process also puts additional load on the processing hardware. One of the proposed solutions is the use of group messages, which allows data transmission only to related devices that are in close proximity [47]. This in turn decreases the load on networking and processing hardware. It is important to state that group messages only solve the problem of data reception from road side units, but the problem of  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**C-V2X Operating Band** & **Uplink, MHz** & **Downlink, MHz** & **Interface** & **Maximum Bandwidth, MHz** \\ \hline
47 & 5855–5925 & PC5 & 30 1  \\
3 & 1710–1785 & 1805–1880 & Uu & 20 \\
5 & 824–849 & 869–894 & Uu & 20 \\
7 & 2500–2570 & 2620–2690 & Uu & 20  
data transmission during overcrowded situations still remains. It is also important to note that C-V2X networks share the same resources as mobile users, which add additional network loading and delay control signals. With the arrival of 5G NR, C-V2X-based communication will have to handle handovers from LTE to 5G NR and vice versa, which adds complexity to system design.
# Evaluation of Bol Corrosion Degree Based on Non-Destructive Testing and Neural Network
## 5 Experiment Results and Analysis
### Ultrasonic Guided Wave Test Waveform  
#### 5.2.1 Experimental Ultrasonic Guided Waveforms  
From Figure 12, it can be observed that the signal waveform of an intact anchor bolt typically exhibits a clear and regular pattern, with the peak and center frequencies of its primary wave remaining stable and without additional reflected wave signals. In contrast, the signal waveform of a defective anchor bolt displays a complex pattern due to the superposition of a defect reflection wave signal, resulting in a shift in the peak and center frequencies of its primary wave. This superposition also leads to a certain degree of phase shift in the received waveform.  
In the figure, the second wave packet represents the echo reflected from the corrosion defect on the anchor bolt, while the third wave packet corresponds to the echo reflected from the bottom surface of the anchorage. In measuring the time intervals between each wave arrival, the position of the anchor bolt corrosion defect and the length of the free segment and anchorage section can be calculated. The first wave peak occurs at 0.120 ms, the echo from the anchorage surface arrives at 0.29 ms, the echo from the corrosion defect arrives at 0.474 ms, and the echo from the bottom of the anchorage arrives at 0.671 ms. Based on the calculation of group velocity from the time-domain waveform, the propagation speeds of the guided wave in the free section and the anchored section of the anchor bolt are 5748 m/s and 4959 m/s, respectively. Therefore, the free segment of the anchor bolt was determined to be 48.86 cm, the position of the corrosion defect was at 89.27 cm, and the length of the anchorage section was 100.02 cm. The calculation yielded a 2.97% error in the position of the defect and a total length of 148.88 cm with a 0.75% error.  
Figure 13 shows the guided wave signals of anchor bolts with different degrees of corrosion in actual experiments. It can be observed that in practical situations, due to  
Figure 11: Actual signal acquisition.  
Figure 12: Ultrasonic guided wave waveform diagram for anchor bolt non-destructive testing. (a) Normal anchor bolt Waveform graph. (b) Waveform graph of anchor bolt after 12 h of corrosion.  
uncertainties in corrosion and the presence of phenomena such as the dispersion and overlapping of guided waves, the amplitude, time delay, and frequency attenuation of the reflected guided wave signals become more complex. These variations also affect the resolution and identification accuracy of the signals. It is important to consider these influencing factors during data processing and analysis in order to improve the reliability and accuracy of the signals.
# Tibetan Speech Synthesis Based on Pre-Trained Mixture Alignment FastSpeech2
## 3 Experiments and Results
### Ablation Studies  
To understand the contributions of different components in our mixture alignment FastSpeech2 model, we conducted ablation studies. Specifically, we evaluated the impact of the pitch predictor, energy predictor, and mixture alignment mechanism on the overall performance. We conducted comparative mean opinion score (CMOS) evaluation for these ablation studies. The results are shown in Table 8. We found that removing the energy predictor in mixture alignment FastSpeech2 results in a performance drop in terms of voice quality, indicating that the energy predictor is effective in improving voice quality. Additionally, removing the pitch predictor results in CMOS decreases of \(-0.11\), demonstrating the effectiveness of the pitch predictor. When both pitch and energy predictors are removed, the voice quality drops even further, indicating that both pitch and energy predictors are crucial for enhancing the performance of mixture alignment FastSpeech2.  
To validate the effectiveness of the mixture alignment mechanism, we compared mixture alignment FastSpeech2 with mixture alignment against FastSpeech2 with hard alignment. The experimental results are shown in row 5 of Table 8. The results indicate that mixture alignment FastSpeech2 performed better. This finding confirms the effectiveness of the mixture alignment mechanism.
## 3 Crack Detection and Crack Localization with Multiple PD Measurements
### Crack Detection in Single Edge Notched Specimens
In a further sample shown in Figure 12b, an additional laser notch was used to force a crack initiation in the center of the notch root. The contour of the first overload (N = 15,000) shows this crack having a length of 0.7 mm and a depth of 0.2 mm. After 30,000 cycles, an additional crack has formed at the backside of the sample. The formation of both cracks is visible in the run of the potential quotients \(Q_{Front}\) and \(Q_{Back}\). The formation of a crack in the center of the notch root leads to a decrease of both potential quotients starting from around 11,000 cycles. The formation of the secondary crack is obviously initiated by the application of the overload at 15,000 cycles and results in a separation of the previously congruent potential curves: the potential quotient \(Q_{Back}\) decreases less than the quotient \(Q_{Front}\). The investigations have shown that the multiple potential drop measurement allows an early detection of crack initiation in SEN-specimens. The calculation of potential ratios eliminates temperature effects and therefore enhances the sensitivity of crack detection. Additionally, the formation of secondary cracks can be detected via this method. In addition to the detection of crack initiation, this method also gives information about the crack front geometry of long cracks.
# Performance Tuning for Power Electronic Interfaces Under VSG Control
## 2 VSG Emulation Control Strategies for VSIs with Frequency Control
As the VSG algorithm can fully emulate the frequency control performance of the SGs, the multiple temporal frequency control is also provided by the VSG-PEIs. For quantitative analysis, the performance indices mainly include the maximum ROCOF, the frequency nadir, the settling frequency, and the settling time, which are shown in Figure 2.  
Figure 1: \(Cont\). Furthermore, in a small synchronous area, the equivalent inertia constant \(H_{sys}\) of different VSG-based PEIs and SGs can be expressed as  
\[H_{sys}=\sum_{i=1}^{n}\left(H_{i}\frac{S_{i}}{S_{sys}}\right) \tag{5}\]  
where \(n\) is the total number of generation units with inertia properties, \(H_{i}\) and \(S_{i}\) are the inertia constant and power rating of the \(i\)-th unit, respectively, \(S_{sys}\) is the power base of the system [32, 36]. Also, the equivalent speed droop \(R_{eq}\) can be expressed as  
\[R_{eq}=\frac{1}{\sum\limits_{i=1}^{n}\frac{1}{k_{i}}} \tag{6}\]  
Figure 1: Control structure of AGC: (**a**) AGC on synchronous generators and (**b**) virtual AGC on VSG-PEIs. Figure 2: Multiple temporal stages of frequency response after a step increase of load. where \(R_{i}\) is the speed droop property of the \(i\)-th generation unit [16]. Consequently, for a local synchronous system, the generation units can be simplified and equivalent to a single unit. The emulation strategy mentioned before could be considered as the overall characteristics of the entire local synchronous area. Then once the parameters are tuned, it could either be used to control the dominated PEI in a stand-alone system or calculate the parameters reversely for individual units with inertia properties.