esa-sceva/satcom-chunk-collection huggingface dataset:
# ATC Human Factors Involved in RPAS Contingency Management in Non-Segregated Airspace
## 2 Method
### Nominal RPAS Conditions and Contingencies into Non-Segregated Airspace
#### 2.3.3 RPAS Engine Failure Contingency
The collection of alternative trajectories must provide early and late flight termination alternatives. Early flight termination should be employed in the case of range/performance limitations or any other operational airport or ATCO requirement when the contingency occurs. Late alternates should be available when meteorology or operational restrictions change along the contingency procedure, rendering the initially planned emergency landing location unfeasible. Alternative trajectories should avoid overflying populated zones or highly elevated areas such as mountains. The ATCO must have available alternative routes to achieve predictable behaviour in case of needing to modify the RPAS nominal route at flight time. The new trajectory should minimise interaction with other airports, particularly with the controlled traffic region near the selected landing airfields. In addition, trajectories near the landing site could require extensive descent. Potential external factors, such as wind direction, could become an operation initially deemed feasible into unfeasible. 3. RPAS pilot-ATC communication: The RPAS notifies engine failure emergencies through standard radio procedures, declaring the emergency and indicating the targeted airfield and route. During emergency procedures, the RPAS pilot should keep up to date with the ATCO and indicate whether the RPAS would reach the intended airfield or need to divert to a closer alternative aerodrome or a designated termination area. The process should be as much as possible equivalent to those employed by airliners or instrumented flight rules aircraft. Figure 2: Emergency airfield selected for an MQ-9 RPAS engine failure contingency. Circles indicate maximum MQ-9 gliding distance (estimated around 90 NM) from mission cruise altitude. Table 3 shows the operational procedure that we define in the event of failure of the RPAS engine as an urgent flight landing or termination [24].
# Fibre Wireless Distributed Antenna Systems for 5G and 6G Services
## 3 Experimental Setup of A-RoF Based DAS
### 5G and 6G Signals Generation  
For signal synthesis, two vector signal generators were used consisting of Keysight M950/8194 series for the 5G and 6G signal, respectively. The 5G-new radio (NR) waveform with a frequency allocation (FA) of 50 MHz bandwidth was emulated using the 5G Toolbox available in MATLAB, followed by the uploading of this signal to Keysight M9502A. The generated signal was allocated five bands of equal FAs bandwidth, accounting for a total of 250 MHz, centred at an intermediate frequency \(f_{1F1}\) of 1.14 GHz. We emulated a 256 QAM modulated signal to an intermediate frequency \(f_{1F2}\) of 12 GHz for a 6G trial. The baud rate was initially set to 12 Gbaud to check the efficacy of the 6G communications.
## 2 Measuring Device  
The GP-5000 GalvaPulseTM set is one of the devices designed to measure stationary reinforcement potential and concrete cover resistivity (basic measurements) or, additionally, corrosion current density (advanced measurements) whileusing the polarization method [32]. The half-cell potential is measured to an accuracy of \(\pm\) 5 mV with the Ag/AgCl electrode. The electrical resistance is estimated to be measured with an accuracy of \(\pm\) 5% [32]. The main elements of the set include the control and recording device (PSION minicomputer), silver-chloride reference electrode (Ag/AgCl), and calibration device (Figure 2).  
The GP-5000 GalvaPulseTM can be used in both laboratory and field conditions. Measurements are made on the surface of the element at the points evenly distributed above the reinforcement. This allows for creating graphical maps of the distribution of measured parameters and facilitates further comprehensive analysis of the results, especially for large-size elements. For the measurements, the reinforcing bar (local hole is required) is connected with the calibrated control and recording device (PSION minicomputer) and with the reference electrode.  
Before the measurements, the location of the tested bar is determined and its continuity along the tested section is checked. Where the electrode is applied, the concrete surface must be properly cleaned and wetted. The recommended concrete resistivity should be no more than 50 k\(\Omega\)-cm. Changes in the moisture content in concrete result in resistivity changes, which, at a given constant current strength, could lead to incorrect measurements of the reinforcement stationary potential. Therefore, the moisture concentration on the tested surface should be maintained as constant throughout the measurement period. Figure 3 shows the connection scheme of the GP-5000 GalvaPulseTM set with the tested reinforcement.  
Figure 2: The GP-5000 GalvaPulseTM set.  
The measuring device must be properly calibrated by entering the coordinates of the measurement points on the test surface, pulse duration (5 \(\div\) 20 s), current strength (5 \(\div\) 400 \(\mu\)A; a higher value is expected for bigger quantity of corrosion products), reinforcing bar parameters (diameter, length, surface area), and by activating (if necessary) the ring that limits the electrode area of operation.  
Information on the criteria for the interpretation of the test results is attached to the apparatus (Table 1). It is possible to infer about the probability of reinforcement corrosion in the examined area, and the corrosion process rate can be estimated based on the value of the corrosion current density, depending on the obtained values of the reinforcement stationary potential and the concrete cover resistivity. Table 1 summarizes the appropriate criteria for measurements performed while using a GP-5000 GalvaPulseTM set. The reference values should not be compared with the measurements that were obtained with other devices [6; 32].
## 4 Discussion
### Salt Marsh Monitoring and Characterization
Similarly, as illustrated in Figure 5, diversity was particularly higher at Mira's salt marsh; however, this study site was located in one of the least deteriorated areas of Ria de Aveiro [33], and as such, it presented a greater length as well as greater ranges of elevation, which conceivably promoted new opportunities for the establishment of additional species (Figure 2) not as adapted to the more restrictive environmental conditions found within the other salt marshes that were degraded and characterized by less soil elevation and more inundation (Figures 1, 3 and 4). Furthermore, at Mira, S. _perennis, A. portulacoides,_ and J. maritimus_ were found at slightly higher elevation intervals (Figure 6), while S. _maritimus_ was compelled to even lower more stressful surroundings despite the greatest elevation ranges found in this study site (Figure 2). The preceding strongly suggests that the occurrence of the different new species likely changed the dynamic between species competition and/or facilitation interactions, which are known to be frequent in disturbed environments [51; 52]. Such competitive interactions at salt marshes are usually associated with a trade-off between competition and physiological tolerances, which posits that more elevated and less stressful intertidal zones are typically occupied by stronger competitors who ultimately limit the upper boundaries of the weak competitors to lower stressful physical environments [27; 30; 50; 53; 54]. Therefore, it is reasonable to determine that from the observed core species, A. _portulacoides_ was the most competitively dominant species and S. _maritimus_ the least. This assertion is further supported by one other investigation [55], where the authors, while following both a young and a mature salt marsh, verified that A. _portulacoides_ largely colonizes and dominates most of the middle marsh areas, displacing species such as S. _perennis_ and S. _maritimus_ (common to our study) to lower elevations. The observed dominance of A. _portulacoides_ was most certainly related to its ability to form denser stands that make it difficult to coexist with other species [56]. However, as evidenced in our results and in [55], not even the robust morphology of this species could prevent the later invasion of taller and much more competitive species when the conditions become favorable. Eventually, plants with C4 photosynthetic pathways, such as E. _repens_ and S. _versicolor_ (found in Mira), outcompete C3 species, such as A. _portulacoides_ and S. _perennis,_ that have slower rates of biomass production and thus a more limited ability to grow rapidly and are usually less efficient in the use of available nitrogen and water [1; 57; 58].
# Path Planning for Conformal Antenna Surface Detection Based on Improved Genetic Algorithm
## 3 Improved Genetic Algorithm Combining the Historical Optimal Population
### Selection Operation  
The selection operation is an important way to ensure the continuity of good individuals. In this paper, the elite selection strategy was adopted to select the next generation from the population composed of the parent population, the offspring population, and the historical optimal population, and to introduce new individuals into the population at the appropriate time. The specific steps are as follows:  
Step 1. Sort the populations from lowest to highest fitness and record the number of individuals \(N\) after removing the historically optimal population;  
Step 2. Eliminate duplicated individuals and record the number \(n\) of remaining individuals;  
Step 3. Compare the size of \(n\) with \(N/2\); if \(n\geq N/2\), take the first \(N/2\) individuals of the remaining individuals as the next generation to participate in the next cycle; if \(n<N/2\), take all the remaining individuals as the next generation of individuals and use the probability-based four-nearest-neighbor method to supplement the \(N/2-n\) individuals.  
Compared with the traditional roulette and tournament selection strategies, the elite selection strategy avoids the individuals in the population converging to be the same at a later stage and improves the probability of jumping out of the optimal solution by introducing new individuals.  
Figure 10: Neighbor-node exchange operation. “i+1” and “i+2” denote nodes that need to be replaced in the connection order.  
Figure 9: 3-opt operation. “i+1” denotes a node that needs to be replaced in the connection order.
## 2 The Modified Empirical Wavelet Transform Method
### The LWM-EWT Method  
The process of spectrum segmentation is the basis and is very important for the EWT algorithm to achieve ideal separation results. When the signal has a relatively obvious peak frequency, the above-mentioned segmentation method is effective. However, when AE signals from the damage characteristics that have some frequency bands are processed, some local maxima which are from noise or frequency dispersion might appear and be mistakenly kept in the peak frequency sequence, then this method may lead to a false segmentation. Another drawback of the spectrum segmentation is that the boundary method, which is to obtain the midpoint of the two adjacent local maxima, is too simple, especially when the distance of two local maxima is far, and the extracted signal bandwidth will be too wide.  
When the EWT method is used to process the AE signals, a modified method is proposed in this paper. This method can avoid the improper segments, detect the local maxima and obtain the frequency boundaries. The method is the local window maxima (LWM) segmentation algorithm which means finding the local maxima in a proper window which can be determined according the damage signal features. The process is as follows:  
1. Use the FFT algorithm to obtain the spectrum of the AE sensor signal.
2. According to the characteristics of the AE signals from composite structures, set the window value \(W\) and the segmentation numbers \(N\) (the two parameters are discussed in Section 3).
3. Set the counts of local window maxima \(m=0\).
4. Search all the local maxima of the signal spectrum.
5. Sort descending the local maxima, save the first one as one LWM and set \(m=m+1\).
6. Center on the LWM which is generated from step 5 and zero other spectrum values in \(W\).
7. If \(m\) is not equal \(N\), go back to step 4.
8. Calculate the minimum distance \(L\) of all the two consecutive LWM.
9. Obtain the boundaries according to the \(L\) and each LWM, for example, if LWM-1 is the first LWM and \(\Omega_{1}\) is the frequency of LWM-1, then boundaries for LWM1 are given in Equation (6):  
\[\left\{\begin{array}{ll}\omega_{0}=\Omega_{1}-\frac{L}{2}\\ \omega_{1}=\Omega_{1}+\frac{L}{2}\end{array}\right. \tag{6}\]  
The procedure of the LWM-EWT method is compared with the EWT method in Figure 2 and the improvements are highlighted in the dotted red area.  
The purpose of the proposed method is to find the proper local maxima and how to obtain boundaries. Here the details are discussed. To detect the LWM, the idea is that the most important maxima in the magnitude of the Fourier transform of the sensor signal is significantly larger than the other existing maxima.
## 3 Results and Discussion
### Thermal Desorption of Stored NO\({}_{x}\)
In order to establish if these decompositions can be attributed to nitrite and/or nitrate adsorbed species, the NO\({}_{\rm x}\)/O\({}_{2}\) molar ratio is calculated both from the experimental TPD profile and according to the stoichiometry of barium nitrites (reaction 14) and nitrates decomposition (reactions (15) and (16)):  
\[\text{Ba(NO${}_{2}$)}_{2} \rightarrow\text{BaO}+\text{2 NO}+\text{${}^{1}$}/_{2}\text{O}_{2} \tag{14}\] \[\text{Ba(NO${}_{3}$)}_{2} \rightarrow\text{BaO}+\text{2 NO}+\text{${}^{3}$}/_{2}\text{O}_{2}\] (15) \[\text{Ba(NO${}_{3}$)}_{2} \rightarrow\text{BaO}+\text{2 NO}_{2}+\text{${}^{1}$}/_{2}\text{O}_{2} \tag{16}\]  
The experimental NO\({}_{\rm x}\)/O\({}_{2}\) molar ratios for CZ and Ba6/CZ are collected in Table 3. As can be observed, in the case of CZ, the experimental NO\({}_{\rm x}\)/O\({}_{2}\) molar ratio is 2.8 at low temperature, suggesting a coexistence of mostly nitrites and nitrates on the catalyst surface, in accordance with the literature for ceria-based catalysts at low temperatures [19; 54]. On the other hand, at high temperatures, a value near 1.3 is calculated, in line with the presence of nitrates (as verified by in situ DRIFTS experiments, Figure S3 on SI) adsorbed on this catalyst. On the contrary, Ba6/CZ presents values very close to 1.3, from 250 \({}^{\circ}\)C, which is theoretically attributed to barium nitrate decomposition [19], if it is assumed that most part of stored NO\({}_{\rm x}\) species are located on the Ba sites (reactions (14)-(16)). Therefore, it seems reasonable to establish that the NO\({}_{\rm x}\) species are stored mostly as nitrates in Ba6/CZ. Unfortunately, the corresponding in situ DRIFT spectra did not allow us to confirm this hypothesis (see Figure S4 in SI). Considering the Cu-based catalyst, the resulting TPD profiles recorded after cycling at 150 \({}^{\circ}\)C (Figure 7b-d) and 300 \({}^{\circ}\)C (Figure 8b-e) are almost flat, i.e., without prominent peaks of NO\({}_{\rm x}\) species evolution. In the case of the Cu2/CZ system, this could be explained by the very low storage capacity of this system that results in the absence of NO\({}_{\rm x}\) on the catalyst surface at the end of the cycling process. On the other hand, in the case of Ba6/Cu2 CZ and Ba11/Cu2 CZ, this confirms the important role of copper in achieving the complete reduction of adsorbed NO\({}_{\rm x}\) species during cycling, which is an important feature that has to be accomplished when considering the design of effective NSR systems in combination with other after-treatment strategies.
## 5 Discussion
### Benefits of Collaborative VR to Documentation Review and Risk Assessment  
The results of our user testing demonstrate that the concept of documentation review and risk assessment in VR was rated positively by the participants. Our concept was tested with the COVE-VR platform, but any collaborative VR environment with similar tools would offer an efficient platform for maintenance documentation review and risk assessment processes. The DocPanel tool offers the ability to test maintenance methods and concurrently review the technical instructions, even when there is no physical equipment available. In comparison to working independently with files on a laptop, collaborative VR offers the ability to show how a task is performed, to point out components, and to demonstrate their functionalities. It also introduces an enhanced sense of being together and working as a team. The user test participants noted that the combination of people and departments in our tests was good, but clear roles are needed so that everybody knows what to do. For example, before a review session starts, it must be defined who is responsible for operating the DocPanel and leading the documentation review and who takes notes of any needed changes.  
Spatial understanding is essential for many industrial processes [54]. For example, in maintenance method development, it is important to understand whether there is enough space to carry out the maintenance task. The sense of scale is easily lost when looking at the 3D model from computer screen, which can lead to maintenance methods that are impossible to perform. The related maintenance instructions are then impossible to follow, which can then both frustrate the users and cause safety issues when the users invent their own way of performing the task. These kinds of mistakes are avoided with the 1:1 scale in VR, as VR creates a sense of spatial understanding.
## 3 Results
### Spatial Distribution of Elements  
The highest concentrations were recorded in the sampling points closest to the factory for Fe, Cr, Cu, Hg and Pb in the SE direction (downwind) and in October. See Figure 6 and in Appendix A: Figure A1. A clear decreasing concentration gradient in both prevailing wind directions (SE, NW) with increasing distance from the factory was detected for Al, As, Cr, Cu, Fe, Hg, Pb, V and N. Moreover, it seems that the correlation of Al, As and V is reflected in their spatial distribution (compare Figure 5 with Figures 6 and A1). The elements concentrations were affected by sampling from the ground (TR1-11/13/21), and we suppose that the gradient disruption in June can be connected to the contamination of samples by soil particles. An unclear or increasing gradient was recorded for Mn, Zn, Cd and Ni (similarly as in [43]); Zn and Cd had a comparable spatial distribution which reflected the correlation once again (Figure 5). Though Mn is present in emissions of steelmaking processes in significant amounts, the spatial behaviour of Mn stays unclear and the steelmaking-associated gradient was not confirmed by biomonitoring so far [33; 35; 39; 90; 98]. This can be connected to the solubility and mobility of Mn. Mn is in the form best accessible to plants while in an acid environment with low redox potential, and therefore its intake is significantly higher in spring and coniferous woods, which can explain its variance in surroundings.  
Figure 5: Correlation plot June (**a**) and October (**b**). Size of the point indicates the strength of the correlation, blue—positive, red—negative correlation; crossed points indicate non-significant correlations.  
Moreover, Zn, Cd and Ni are pollutants inevitably present in emissions from both primary and secondary metallurgy carried by fine particles (\(<\)PM\({}_{2.5}\)) [12; 14; 99]. Consequently, they are significantly more influenced by the immediate atmospheric dispersion situations and, thus, by different meteorological conditions in winter (not only wind speed and direction). Gradient charts of these elements in Figures 6 and A1 (in Appendix A) show that following the summer (in October), the downwind decreasing gradient is more evident, considerably in the case of Ni. This can also refer to the fact that more pollution sources are emitting these elements in winter.  
Figure 6: Gradients of concentrations of the assessed elements in terrestrial mosses collected in the surroundings of the Trinec Iron and Steel Works.  
The sampling design also covered two leeward sites (N, SSW direction) and three sites on the hillside (SSW direction) expected to be affected by the factory minimally (Figure 4). However, this assumption was confirmed only for the sampling sites at the Javorovy hill (except for concentrations of Mn, which were already discussed above). The results showed that the site on the north was directly influenced by sintering processes (highest concentrations of Pb and Cu), while the site on the south by the slug dump (highest concentrations of Mn and Cr).
# Ionospheric Narrowband and Wideband HF Soundings for Communications Purposes: A Review
## 3 State of the Art of Sky Wave Sounding
### Antarctica Project
#### 3.5.2 System Deployment  
The project was sounding the channel from 2003 to 2014, which is almost a complete solar cycle. Additional information about the duration of the last five campaigns can be found in Table 3.  
This system was deployed with one transmitter in Livingston island, Antarctica (62.7 \({}^{\circ}\)S, 299.6 \({}^{\circ}\)E), and one receiver with three different antennas in Cambrils, Spain (41.0 \({}^{\circ}\)N, 1.0 \({}^{\circ}\)E). The resulting ionospheric radio link is a trans-equatorial path, which is 12,760 km long. Figure 8 shows a map with geogr  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Survey** & **Start** & **End** & **\#** \\  & **Date** & **Date** & **Days** \\ \hline
2009/2010 & 01/01/2010 & 02/02/2010 & 33 \\
2010/2011 & 22/01/2011 & 01/03/2011 & 39 \\
2011/2012 & 13/02/2012 & 25/02/2012 & 13 \\
2012/2013 & 05/01/2013 & 24/02/2013 & 51 \\
2013/2014 & 24/01/2014 & 18/02/2014 & 26 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Start date, end date, and number of days per survey for the last five studied campaigns.  
The transmitter was placed at the top of a hill close to the Station (see Figure 10a for a block diagram and Figure 9a for a picture of the location). The receiver was placed in Cambrils, a village located 100 km south of Barcelona, in a quiet electromagnetic environment. A block diagram of the receiver is shown in Figure 10b and a photograph is shown in Figure 9b.
## 3 Numerical Modelling Setup
### Computational Fluid Dynamics (CFD)  
The CFD setup was conducted as explained in Part 1, based around the preliminary blade design [1]. The CFD was conducted using ANSYS CFX (18.2, ANSYS Inc., Canonsburg, Pa, USA) with the built in turbo mode. A 3-D overview of the CFD setup is shown below in Figure 7. The scalar values of the boundary conditions used for the simulation are shown below in Table 2.  
* The fluid is modelled as air (ideal gas).
* K-\(\omega\) shear stress transport turbulence model was chosen, which uses an automatic wall function, which automatically switches between a wall function and low-Re wall treatment.
* Interfaces between stator and rotor, and rotor and outlet are selected as stage (mixing-plane).
* Interfaces between stator blades and interfaces between rotor blades are set as periodic.
* The meshes were setup using ANSYS Turbo Grid consisting of a total of 267,089 nodes. From previous investigation, this was found to be acceptable for accuracy.
* Stator blade average Y + 12.2053.
* Rotor blade average Y + 9.8685.  
\begin{table}
\begin{tabular}{c c} \hline
**Boundary Conditions** & **Value** \\ \hline \hline Inlet Mass Flow Rate & 0.127238 kg/s \\ \hline Inlet Total Temperature & 1168.55 K \\ \hline Inlet Turbulence Intensity & 5\% \\ \hline Outlet Static Pressure & 1.30352 bar \\ \hline Rotational Speed & 158,850 rpm \\ \hline \end{tabular}
\end{table}
Table 2: Computational fluid dynamics (CFD) boundary conditions at design point [1].  
Figure 6: Schematic outlining the design evaluation process used in ANSYS Workbench 18.1.