esa-sceva/satcom-chunk-collection huggingface dataset:
## 2 International Typical Transmitting Antenna Reference
### Structure and Performance Design of Typical Loran-C Transmitting Antenna  
#### Single-Tower Antenna Form  
As the main antenna form of the global Loran-C transmission system, the single tower antenna is usually an umbrella antenna supported by a 200-300 m high tower. The radiator is composed of mast, top line and bottom lead. Part of the top line below the line leads to the lower line at the bottom of the tower feed point. The whole radiator is in a conical umbrella shape. The representative schematic diagram of the structure is shown in Figure 5. The top of the tower is powered by several load top conductors as umbrella conductors, which are connected to the ground through insulators, and the bottom of the mast is connected to the ground through an insulator base. The radiation grounding grid is set with the iron tower as the center, and the ground wire is buried underground. The transmission power of the system is 2000 kW. Table 1 shows the performance indexes of the one-tower transmitting antennas designed with reference to Figure 5 at different heights [8; 9].  
The main advantages of the single tower umbrella antenna are that the main body of the antenna system is supported by only one iron tower, the antenna structure is relatively simple, the radiation efficiency is high, the engineering quantity is relatively small, the cost is low and the cost performance is high. Its main disadvantages are that the central tower needs to be insulated from the ground, the performance requirements of the base insulator are very high and the seismic performance of the system is lower than that of the four-tower inverted cone antenna. In addition, in areas prone to s  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**The height of Single-Tower Antenna (m)** & 280 & 250 & 200 \\
**Antenna efficiency (\%)** & 78.2 & 77.2 & 70.61 \\
**Input resistance (f)** & 8.09 & 6.4 & 3.84 \\
**Ground Loss Resistor (f)** & 1.76 & 1.44 & 1.13 \\
**Static capacitance (nF)** & 7.57 & 7.25 & 5.79 \\
**Antenna bandwidth (kHz)** & 3.84 & 3.0 & 1.42 \\
**Product of efficiency and bandwidth (kHz)** & 3.0 & 2.33 & 1 \\
**Effective height (m)** & 189 & 168.1 & 124.4 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Main Performance Parameters of the Single-Tower Antenna.  
Figure 4: Satellite image of a Chayka system transmitting antenna in Russia.  
storms, there may be the risk of system short circuits and work interruption caused by the inundation of the base insulator.
# Dynamic Responses Measured by Optical Fiber Sensor for Structural Health Monitoring
## 5 Conclusions  
Fiber Bragg grating sensors have been proved to be well suited to structure health monitoring over conventional electrical sensors with the capability of multiplexed strain measurements. In this work, an optical fiber sensing system consisting of an FBG sensor, an LPFG filter, and a photodetector was successfully utilized to measure the transient and vibration responses of a structure subjected to shock and vibration loadings. The shift of wavelength reflected from the fiber Bragg grating sensor induced by the applied strain is converted to a light intensity variation through a long period fiber grating optical filter. Strain measurements of a beam subjected to base excitation, drop and impact tests were presented and the results were validated with the output of strain gauge. The present study demonstrates that dynamic strain measurements using the FBG sensor integrated with an LPFG optical filter and a photodetector can be used to monitor the transient and vibration responses of structures. The aim of the present work is to provide a fast-response and easy-to-implement sensing system for structural health monitoring based on real-time dynamic strain measurements. The experimental setup and measuring technique presented in this study are simple and easy to implement. It is helpful and useful in terms of the practical applications in industry.  
Conceptualization, S.-C.H.; Methodology, S.-C.C.; Validation, S.-C.C.; Formal analysis, S.-C.H.; Investigation, S.-C.H.; Writing--Original draft preparation, S.-C.H.; Writing--Review & editing, S.-C.H.; Visualization, S.-C.C.; Supervision, S.-C.H.; Project administration, S.-C.H.; Funding acquisition, S.-C.H.  
Figure 16: Acceleration of the drop table.  
Figure 17: Transient response of a beam subjected to the drop test.  
**Funding:** This research was funded by Ministry of Science and Technology of the R.O.C grant number MOST 107-2221-E-155-029 and The APC was funded by Ministry of Science and Technology of the R.O.C.  
**Conflicts of Interest:** The authors declare no conflict of interest.
# Efficient Low-Complexity Turbo-Hadamard Code in UAV Anti-Jamming Communications
## 2 System Model
Since our emphasis in this paper is on improving the FH code scheme, the received signal is assumed to be demodulated and synchronized perfectly. As a consequence, the sequence to be decoded \(\hat{e}_{n},n=1,\cdots,N\) can be represented equivalently as  
\[\hat{e}_{n}=\left\{ \begin{array}{ll}0,&\text{probability }\phi/\Phi,\\ \mathbf{c}_{n}+\hat{\omega},&\text{probability }1-\phi/\Phi,\end{array} \right. \tag{5}\]  
where \(\mathbf{c}_{n}\) denotes the ideal demodulated result, and \(\hat{\omega}\) is the equivalent AWGN of which the power spectral density is \(\omega_{0}\) due to the application of the optimum receiver. Finally, the receiver in the UAV communication system can obtain the decoded bits \(\hat{\mathbf{u}}\) after the turbo-Hadamard decoder progress.
# Virtual Power Plant Optimization in Smart Grids: A Narrative Review
## 4 VPP Applications in Smart Grids  
The main identified research works are briefly presented and classified according to the VPP usage and applicability in specific smart grid energy management scenarios or strategies:  
* VPP coordinates energy resources for collectively providing energy services in different markets or directly to interested stakeholders such as a DSO;
* VPP coordinates energy resources for local energy autonomy to achieve an optimal balance between the demand and supply and to minimize energy exchanges among microgrids and the main grid;
* VPP coordinates energy resources for the optimal implementation of sustainable energy communities considering in addition to energy aspects the local economic and social factors.
# Numerical Analysis on Spanwise Correlation of Vortex-Induced Force of Split Double-Box Beam
###### Abstract  
The vortex-induced force of bridges is not synchronized along the span direction. The spatial correlation of vortex-induced force becomes obvious when the span of the bridge structure gradually increases, and the mass gradually decreases. Therefore, it is important to study the spanwise correlation of vortex-induced forces of long-span bridges to ensure the accuracy of the prediction of vortex-induced vibration response of bridges. The study established and improved the theory and experimental research methods for vortex-induced vibration analysis of large-span bridges by discussing the spanwise correlation during vortex-induced vibration of the split double-box beam. Taking Xiboumen Bridge as the object, two-dimensional (2D) and three-dimensional (3D) numerical models of the scaled-down sections were designed and established based on the ANSYS Fluent platform and the RANS SST turbulence model. Based on the Newmark-\(\beta\) algorithm, a User Defined Function (UDF) was written for vortex vibration calculation, the three-dimensional bypass of the split double-box beam in static conditions and vortex-induced vibration of the split double-box beam of which were calculated, and the spanwise correlations of the aerodynamic coefficients, the surface pressure coefficients, and the wake wind velocity of the main girder section were analyzed for the static and vibration states of the bridge. The results show that the self-excited force of the split double-box beam in vortex-induced vibration improved its spanwise correlation. Compared with those in a static state, the spanwise correlation of the lift coefficient and torque coefficient increased by 55% and 87%, respectively, and the resistance coefficient increased by more than 10 times. The correlation of the pressure coefficients increased by 153%. The correlation of wake wind velocity is increased by 37% in the along-wind direction and that in the across-wind and vertical-wind direction increased by more than 10 times. The accuracy of the numerical simulation results was verified by comparing the pressure distribution and pressure spanwise correlation of the main beam with field-measured data.  
stiff double-box beam; spanwise correlation; CFD; vortex-induced vibration; surface pressure; wake velocity +
Footnote †: journal: Applied Sciences
# A Haar Wavelet Decision Feedback Channel Estimation Method in OFDM Systems
## 5 Simulation Results
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Tap**} & \multicolumn{2}{c}{**CDT1**} & \multicolumn{2}{c}{**CDT6**} \\ \cline{2-5}  & **Delay (\(\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{ \mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{ \mathbf{ }}}}}}}}}}}}}}}\) & **Delay (\(\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{ \mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{ }}}}}}}}}}}}}}}\) & **DownDown (\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{ \mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{ }}}}}}}}}}}}}}}} \) & **Power (dB)** \\ \hline
1 & 0 & 0 & 0 & 0 \\
2 & \(-1.8\) & \(-20\) & \(-18\) & \(-10\) \\
3 & 0.15 & \(-20\) & \(-1.8\) & \(-20\) \\
4 & \(1.8\) & \(-10\) & \(0.15\) & \(-20\) \\
5 & \(5.7\) & \(-14\) & \(1.8\) & \(-10\) \\
6 & \(18\) & \(-18\) & \(5.7\) & \(-14\) \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Profiles for China DTV Test 1 st (CDT1) and CDT6 multipath fading channels [17]. \begin{table}
\begin{tabular}{c c} \hline \hline \multicolumn{1}{c}{**Parameters**} & \multicolumn{1}{c}{**Specifications**} \\ \hline System model & wavelet-OFDM/CP-OFDM \\ Modulation mode & QPSK \\ CP length (subcarriers) & 128/140 \\ Subcarrier number & 512 \\ OFDM block length & 10 \\ Doppler spread & 20 Hz \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Parameters for wavelet-OFDM and CP-OFDM systems.
## 1 Introduction
It advocates for the combined detection method of radio interference detection and spoofing source identification and localization to maintain the credibility of VDES data links. To accomplish this overall goal, the following research objectives were established:  
1. To detect radio interference in the VDES data link, a radio interference detection approach based on message characteristics is put forward. By examining adherence to message formats, parameter validity, content integrity, and transmission coherence, it is determined whether radio interference will impact the correct transmission of VDES messages. 2. Due to the lack of encryption in the messages broadcast by VDES base stations and the absence of an identity verification mechanism within VDES itself, malicious entities could deceive vessels within the signal coverage area by illicitly sending false VDES messages using the MMSI code stolen from a legitimate base station. This deceptive practice can mislead vessel navigation decisions, posing a significant threat to maritime safety. This paper employs a method for spoofing source detection based on distance matching analysis. Specifically, the VHF signal propagation loss model in the complex sea environment is employed to calculate the propagation distance of the VDES signal, and the position information in the ship position report is utilized to calculate the ship-to-shore distance. The matching degree analysis of the two distances is adopted to effectively identify the spoofing source, and the spoofing source position and range are then located by using the spoofing source positioning algorithm. 3. To automatically monitor the credibility of the VDES data link and issue timely warnings of vulnerabilities to vessels or management centers, this study develops monitoring software based on a tripartite data architecture supported by a client/server (C/S) model, using the front-end interface to display the monitoring results, warning information, and related data visually, facilitating a direct understanding of the credibility of the VDES data link. 4. The credibility monitoring approach and monitoring software for the VDES data link proposed in this paper are verified based on various interference scenarios, and the results indicate that the proposed approach and the developed software system can effectively monitor and identify the vulnerability threats such as radio interference and spoofing sources existing in the VDES data link. The findings of this study provide a foundation for developing high-trust services for VHF data links within a comprehensive maritime navigation support system.
# Resource-Efficient FPGA Architecture for Real-Time RFI Mitigation in Interferometric Radiometers
## 3 Implementation Optimization  
The implementation of any DSP algorithms in FPGAs requires careful optimization to meet real-time processing requirements while efficiently utilizing available resources. This section discusses the key optimization strategies employed through the implementation of the RFI mitigation algorithm.  
Figure 5: PMS Blanking implementation illustrating the application of blanking masks to both high-speed signals and PMS measurements. Rate conversion and gain correction stages ensure proper synchronization and calibration.
# A Database for Tsunamis and Meteotsunamis in the Adriatic Sea
## 2 Tsunamis and Meteotsunamis in the Adriatic Region
Theb wave heights and spatial extent of meteotsunamis are smaller compared with tsunamis, but they can cause sea level oscillations of several meters and human losses and injuries. Although meteotsunamis are not catastrophic to the extent of major seismically induced events, their occurrence in time and space are higher than those of seismic tsunamis, as the atmospheric disturbances responsible for the generation of meteotsunamis are much more common. According to recent studies [26], extreme weather has been a common result of the planet's rising temperature, and climate change, like global warming and the sea level rising, may have an impact on the future occurrence and likelihood of meteotsunamis. The meteotsunami phenomenon is a relatively recent scientific discovery, considering that the first description of tsunami-like effects produced by atmospheric disturbances appeared only in 1931 [27] and that the term \"meteotsunamis\" was introduced only in 1961 [27]. Thus far, it has been shown that Mediterranean meteotsunamis tend to be stronger in summer. Despite calm conditions at ground level, fast winds of dry air from Africa in the atmosphere 1500 m up seem to trigger atmospheric waves. Mostly during summertime, small-scale strong atmospheric disturbances take place in the Adriatic area, and the coast has a quite complex topography, with a large number of funnel-shaped bays and harbors which have high amplification factors. In fact, the strength of a meteotsunami is also largely dependent on both the topography and the bathymetry of the affected area, and in the Adriatic Sea, recurrent meteotsunami events are known to strongly impact the lifestyles of the coastal communities, particularly in the Dalmatian islands, where meteotsunamis can generate serious flooding. Several destructive events affected the eastern Adriatic shore in the last few decades, mainly involving Mali Losinj, Ist, Stari Grad, Vela Luka and Mali Ston. The strongest event hit Vela Luka in Croatia in June 1978, with a wave height of 6 m (crest to trough) and a period of 18 min. This meteotsunami, the most powerful recorded in the Mediterranean, lasted several hours and caused USD 7 million in damage [28; 29]. Siroka Bay in the island of Ist and Mali Losinj Bay in the island of Losinj are the two days in the northern Adriatic where destructive meteotsunamis have occurred recently. Four-meter waves struck Siroka Bay on 22 August 2007, injuring one person and damaging local infrastructure [26]. This locality also experienced meteotsunami effects on 4 October 1984. Mali Losinj Bay was hit on 15 August 2008 by 2-m waves, flooding a forefront of the most populated town of the Adriatic Sea islands and causing a panic during tourist season [30; 31].
## 5 Conclusions  
In this paper, two photopolymer layers sensitive to two different wavelengths were stacked together and lenses were recorded in each layer. Initially, a theoretical design was developed in order to determine the recording conditions needed to achieve an efficient element. An acriflavine-sensitized photopolymer material was characterized so as to find the recording conditions for the expected range of spatial frequencies. Holographic lenses were then recorded in individual layers at blue and green wavelengths (in the appropriately sensitized photopolymer), which demonstrated uniform and high efficiency at the optimized exposure energies. Dual-wavelength sensitive stacks were then assembled and the sequential recording of stacked lenses was carried out. A set of four stacked lenses were recorded and tested by probing by a He-Ne laser at a wide range of angles for three positions across the element. The angular separation of +1 and \(-1\) order maximum diffraction positions were analyzed. It was found that experimental angular separation matched well with theoretical values for the lenses. It was not possible to resolve the separate diffraction peaks from the blue and green lenses, as they were designed to coincide for blue and green wavelengths; even at 633 nm, the angular separation is expected to be \(<0.5^{\circ}\). Initial tests performed with cylindrically diverging beams showed strong diffraction into collimated off-axis beams for blue, green and white light. With some optimization, this approach could be used to develop stacked DOEs that can re-direct and collimate light with multiple wavelength ranges for potential applications in illumination, solar collection and displays.  
Future work will involve investigating the dual-wavelength layer stacking approach for lenses with different off-axis angles and numerical apertures as well as a more detailed study of the independent photonic structures recorded by this method by deliberately separating the positions of the diffraction peaks.  
[PERSON] carried out most of the experimental work and developed aspects of the methodology as well as preparing the original draft. He acquired the funding for the work as part of a PhD scholarship. [PERSON] contributed to the experimental work in the final section. [PERSON] helped develop the methodology and contributed to draft preparation and data analysis. He is a co-supervisor of this work. [PERSON] assisted with the modeling and data analysis. [PERSON] helped develop the concept, methodology and materials. She is a co-supervisor of this work. [PERSON] helped develop the concept methodology and materials. She is the lead-supervisor of this work. All supervising authors contributed to reviewing and editing. All authors have read and agreed to the published version of the manuscript.  
This research was funded by TU Dublin Fiosraigh PhD Scholarship fund. This research received no funding external to TU Dublin.  
The authors would like to acknowledge [PERSON] for his advice and the FOCAS research Institute for facilities and support.  
The authors declare no conflict of interest.
## 3 Results
In Algorithm 1, we present the computing of performance metrics considering the network organization, from its formation through the coordinating node, establishing hierarchies for the nodes, starting with the highest one, which belongs to the coordinating node. For the metric analysis, we must consider the metrics are related to the nodes and packets. The analysis is carried out by purposely increasing and decreasing all the metrics (each individually and independently) and observing their direct impact on the rest of them and their energy. ```
Start Set initial conditions; Initialize Hierarchy level of coordinator node = Hierarchy; Initialize coordinator node establishes neighbors = i; Calculate reachable_Nodes; for each Node do Establish sent_Packets; Calculate received_Packets; Calculate SNR per link; Calculate control_Packets <- overhead; Calculate traffic_Packets; Calculate Valid_Routes; Calculate obsolete_Routes; Calculate reconfiguration_Time; Calculate RSSI; endfor for each packet do Calculate hop_Number; Calculate delay; Calculate retransmission_Number; Calculate retrizes_Number; endfor
```  
**Algorithm 1** Computing of performance metrics. \begin{table}
\begin{tabular}{l l l} \hline \hline
**Metric** & **Related Metrics** & **Impact on Energy** \\ \hline PDR & Retransmissions, hops & \(\uparrow\uparrow\) \\ Availability routes & Valid routes, hops delay, retransmissions, recovery time (resilience) & \(\uparrow\uparrow\uparrow\) \\ Valid routes & Availability routes, hops, delay, retransmissions, recovery time (resilience) & \(\uparrow\uparrow\uparrow\) \\ SNR & Hops, retransmissions, recovery time (resilience), availability routes, delay & \(\uparrow\uparrow\) \\ Overhead & retransmissions, hops, recovery time (resilience), Valid routes, delay & \(\uparrow\uparrow\) \\ Delay & Hops, recovery time (resilience) & \(\uparrow\uparrow\) \\ Hops & Delay, retransmissions, Availability routes & \(\uparrow\) \\ Retransmissions & Availability routes, delay, SNR, throughput, hops, retransmissions, recovery time (resilience) & \(\uparrow\uparrow\uparrow\) \\ CSMA retries & Availability routes, SNR, throughput, retransmissions, recovery time (resilience) & \(\uparrow\uparrow\) \\ Resilience & Availability routes, delay, SNR, throughput, hops, retransmissions, CSMA retries & \(\uparrow\uparrow\uparrow\) \\ RSSI & Hops, retransmissions, recovery time (resilience), availability routes, delay & \(\uparrow\uparrow\uparrow\) \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Relationship between metrics and impact on energy.
## 3 Methodology  
To analyze the UTM monitoring application, a series of flight tests were conducted involving several small fixed-wing UAVs flying in suburban and rural areas. This section explains the UTM monitoring application setup, Remote ID hardware, UAV frames, locations, and flight test scenarios.