esa-sceva/satcom-chunk-collection huggingface dataset:
# A Blockchain Protocol for Authenticating Space Communications between Satellites Constellations
## 6 Discussion
The third question in this research was to investigate the reliability of the PoST protocol in verifying the valid transactions within the trusted swarms of satellites. As shown in Table 7, the authentication process achieved 100% in terms of the accuracy, true positive rate (TPR), and true negative rate (TNR) of the PoST protocol. These results can be justified due to the ability of the proposed Blockchain protocol, PoST to recognize all valid transactions and reject all unreliable transactions when applied to three different sets of transactions between satellites. This means that the false positive (FP), and false negative (FN) are zero, and this interprets the optimality of the proposed Blockchain protocol in authenticating and verifying satellite transactions whether these transactions occurred in a single constellation or different ones. This finding broadly supports the work introduced in [27] regarding using blockchain for verifying satellite access. Although the obtained results are in line with those in [27], PoST has some advantages that make it better than BAVP (Blockchain-Based Access Verification Protocol) proposed in [27]:  
1. PoST has been tested against the key measures of the blockchain (RL, TL, RT, and TT) while the BAVP has not. This makes the results of this study the leading ones. 2. Although the BAVP achieved good results regarding response time and delay of satellite transactions, it considers neither the size of transactional data nor the frequency of transactions as in the PoST protocol. This may make the results of the PoST protocol more dependable than that of BAVP. 3. In BAVP, the test scenarios focused on only the computation time of the encryption algorithm, (identity-based encryption (IBE)) used in BAVP compared with RSA without introducing any results about blockchain impacts on the efficiency of BAVP as performed with PoST protocol. 4. In BAVP, the authors claimed that this protocol has intrinsic resistance against replay attacks, the man in the middle attack, impersonation attack, and denial of service attack, but there is no evaluation confirming this claim. On contrary, the reliability of PoST against fake satellite transactions has been tested and produced good results (see Table 7). Further research efforts should be undertaken to investigate the effectiveness of the proposed PoST protocol for managing and authenticating other two types of transactions as two case studies:  
1. Investigating how PoST can manage and authenticate the tracking and data relay satellite (TDRS) transactions to improve the amount and speed of uplink and downlink data that could be transferred to or from the TDRS system. 2. Investigating how PoST can be used to immunize a satellite constellation against space debris collisions based on the sensing orbital data between satellites and space debris.
###### Abstract  
Crop yield estimation at a regional scale over a long period of time is of great significance to food security. In past decades, the integration of remote sensing observations and crop growth models has been recognized as a promising approach for crop growth monitoring and yield estimation. Optical remote sensing data are susceptible to cloud and rain, while synthetic aperture radar (SAR) can penetrate through clouds and has all-weather capabilities. This allows for more reliable and consistent crop monitoring and yield estimation in terms of radar sensor data. The aim of this study is to improve the accuracy for winter wheat yield estimation by assimilating time series soil moisture images, which are retrieved by a water cloud model using SAR and optical data as input, into the crop model. In this study, SAR images were acquired by C-band SAR sensors boarded on Sentinel-1 satellites and optical images were obtained from a Sentinel-2 multi-spectral instrument (MSI) for Hengshui city of Hebei province in China. Remote sensing data and ground data were all collected during the main growing season of winter wheat. Both the normalized difference vegetation index (NDVI), derived from Sentinel-2, and backscattering coefficients and polarimetric indicators, computed from Sentinel-1, were used in the water cloud model to derive time series soil moisture (SM) images. To improve the prediction of crop yields at the field scale, we incorporated remotely sensed soil moisture into the World Food Studies (WOFOST) model using the Ensemble Kalman Filter (EnKF) algorithm. In general, the trend of soil moisture inversion was consistent with the ground measurements, with the coefficient of determination (R\({}^{2}\)) equal to 0.45, 0.53, and 0.49, respectively, and RMSE was 9.16%, 7.43%, and 8.53%, respectively, for three observation dates. The winter wheat yield estimation results showed that the assimilation of remotely sensed soil moisture improved the correlation of observed and simulated yields (R\({}^{2}\) = 0.35; RMSE =934 kg/ha) compared to the situation without data assimilation (R\({}^{2}\) = 0.21; RMSE = 1330 kg/ha). Consequently, the results of this study demonstrated the potential and usefulness of assimilating SM retrieved from both Sentinel-1 C-band SAR and Sentinel-2 MSI optical remote sensing data into WOFOST model for winter wheat yield estimation and could also provide a reference for crop yield estimation with data assimilation for other crop types.  
SAR; optical; soil moisture; data assimilation; WOFOST model; yield estimation 2019 11, 1618; doi:10.3390/rs11131618 wwmdpi.com/journal/remotesensing Article
## 4 Evaluation and Discussion
### Keystream Analysis
#### 4.3.3 Key Randomness Analysis  
The keystream generated using the chaotic logistic map function is then subjected to randomness analysis to verify its randomness after being subjected to the Josephus permutation. This testing is performed using the NIST (National Institute of Standards and Technologies) SP 800-22 Test Suite. Research conducted by [PERSON] et al. [28] lists fifteen types of statistical tests, namely, the following:  
1. Frequency;
2. Block Frequency;
3. Cumulative Sums;
4. Runs;
5. Longest Run;
6. Rank;
7. FFT;
8. Non-Overlapping Template;
9. Overlapping Template;
10. Universal;
11. Approximate Entropy;
12. Random Excursions;
13. Random Excursions Variant;
14. Serial;
15. Linear Complexity;  
Randomness analysis of the keystream will be conducted with the values \(x_{0}=0.5\), \(r=3.87\), and a precision level of five digits. Table 5 shows the results of randomness testing of the shuffled keystream with a confidence level of \(\alpha=0.1\). The fifteen types of tests indicate that the keystream from the logistic map that is shuffled by the Josephus permutation is still random.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**No.** & **Test Type** & \(P_{value}\) & **Proportion** & **Result** \\ \hline
1. & Frequency & 0.534146 & 1 & Pass \\
2. & Block Frequency & 0.350485 & 0.9 & Pass \\
3. & Cumulative Sums & 0.534146 & 1 & Pass \\
4. & Runs & 0.739918 & 1 & Pass \\
5. & Longest Run & 0.911413 & 1 & Pass \\
6. & Rank & 0.534146 & 1 & Pass \\
7. & FFT & 0.213309 & 1 & Pass \\
8. & Non-Overlapping Template & 0.739918 & 1 & Pass \\
9. & Overlapping Template & 0.911413 & 1 & Pass \\
10. & Universal & 0.000000 & 1 & Pass \\ \hline \hline \end{tabular}
\end{table}
Table 5: Results of randomness test of keystream.  
It can also be concluded from Table 5 that using the Josephus permutation to shuffle a random keystream does not induce a recognizable pattern in it; hence, the randomness stays present. This acts as an extra layer of security that attackers have to go through before obtaining our secret image.
## 3 Results and Discussion  
### Synthesis of Triphenyl Imidazole Derivatives  
The 2,4,5-trisubstituted imidazole derivatives **1**-**13** were prepared from a 1,2-diketone (benzil), ammonium acetate and the corresponding aldehydes, following the known Radziszewski reaction and the methodology proposed by [PERSON] et al. with some modifications (Scheme 1) [28], with reaction yields of 64-99%. All compounds were characterized by IR and mass spectroscopy, \({}^{1}\)H- and \({}^{13}\)C-NMR. In the \({}^{1}\)H NMR spectra of compounds **1**-**13**, the corresponding signals for the aromatic protons of the rings of position four and five of the imidazole heterocycle were observed, with typical displacements between 7.19-7.69 ppm. For the aromatic system of position two, all of the protons' expected shifts were observed, as were their coupling constants. In the \({}^{13}\)C-NMR spectra, the carbons that formed the imidazole ring were observed at shifts of 159.83-143.20 ppm for carbon two, while those of position four and five were seen at 128.54-127.64 ppm. NMR spectra of the selected derivatives can be observed in Figures S1-S13 in the Supplementary Materials.  
**Scheme 1.** General reaction scheme for the synthesis of 2,4,5-triphenyl-1\(H\)-imidazole derivatives.
## 5 Analysis of Simulation Experiments
### Product Quality Analysis  
In this section, the dissemination of completed products in terms of quality is investigated. For this investigation, RL(EK-CBM) is employed, since it is the best performing version of the proposed mechanism.  
Figure 9 depicts the standard and faulty products produced over the course of the conducted simulations. It is indicated that an increased quantity of standard products is completed and stored in the facilities, while faulty items are either limited or zeroed. The latter observation is supported by Figure 10, which indicates the small quantity of remanufactured items. This clearly illustrates that CBM control policy succeeds at keeping the manufacturing facilities in good condition, due to the observed number of standard products. Additionally, it is likely that the agents preferred to remanufacture faulty items in order to produce enough goods for customers. This contributes positively to the minimization and reuse of product waste in an effort to generate revenues. However, there is a high probability of returning acquired items to the system. The returned are stockpiled in the storage facilities until they are refurbished.  
Figure 10 disseminates the inventory of ready-to-be-sold products. This figure demonstrates that the refurbished items are the ones that fill out the inventory throughout the simulation scenarios. This is a clear indication that customers are constantly dissatisfied with their purchase, and thus they are returning it to the manufacturing/remanufacturing system. These returned items are stored until they are refurbished. Since their number is high, the manufacturing facilities are unable to merely carry out the production process, as the inventory does not have space for new goods. Due to this fact, the produced and  
Figure 8: The variance of (**a**) average refurbishing cost, and (**b**) average remanufacturing cost.  
Figure 9: An illustration of the manufactured product diversity.  
remanufactured items are limited. Nevertheless, the filling of facilities with refurbished items is a clear indication that the two-agent mechanism turns the loss associated with returned products into an effective and sustainable revenue stream for the examined system, since the refurbished items are later sold to customers.
# Independent System Calibration of Sentinel-1B
## 5 Antenna Pointing Determination
### Antenna Pointing Determination in Elevation  
For pointing calibration in elevation, a notch elevation beam is acquired over homogeneous Amazon rain forest and only a flat pattern is applied for pattern correction. Then, by summing up the image in azimuth direction, an averaged range profile is obtained over the whole scene. For each averaged gamma profile, the notch position has been determined based on identifying the minimum position of a polynomial fit to the central part of each measured notch. The antenna mispointing can then be calculated by comparing the position of the measured notch to the corresponding theoretical expectation. Figure 17 shows an exemplary evaluation for one data take.  
Figure 16: Squint angle in azimuth as a function of the antenna look angle. The two dashed lines designate two separate fits to data which were acquired with two different star tracker configurations. Here, the change in configuration resulted in an offset in squint angle. N1–N6: azimuth notch acquisition with different look angles.  
Figure 17: Exemplary elevation notch beam evaluation for HH-Pol acquired on 19 June 2016. The blue curve in the plot on the left shows the full measured notch gamma profile. Marked in red is the central part of the notch which is used for minimum position determination. The plot on the right shows a detailed view of the central notch part (blue dots), a polynomial fit (polynomial of seventh order) based on this central part (red line) and the retrieved minimum position (red triangle) for HH-Pol.  
During the commissioning phase of Sentinel-1B, the spacecraft's star trackers were realigned on 27 July 2016, after the originally planned set of elevation notch measurements had already been executed. This realignment served to reduce the mispointing observed from the first set of measurements. Therefore, a second set of elevation notch measurements was acquired over the Amazon rainforest in August 2016. Detailed results based on all evaluated measurements from this second set of measurements can be found in Table 4.  
For the co-polarized channels, the averaged observed mispointing value is \(-15\pm 3\) mdeg which is the current best estimate for antenna mispointing in roll. This roll offset requires an adjustment based upon the results derived from the co-polarized channels. Note that based on the data sets available, no significant difference in the retrieved mispointing values can been observed between measurements taken from ascending and descending orbits.  
In conclusion, the mean observed pointing offset both in azimuth and elevation should be corrected by re-adjusting the satellite attitude in roll, pitch and yaw accordingly. Then, a further fine-tuning could be achieved by shifting accordingly the corresponding reference patterns derived by the antenna model. The result of this two-step adjustment should be checked by acquiring another set of notch measurements both in elevation and in azimuth.
## 4 Discussion
### Advantages of Sentinel-2 High-Spatial-Resolution Data for GPP Modeling
Although the networking Sentinel-2 system had a five-day revisit period, with more cloudy days during the peak of growing season in some humid climate types, there were limited observations when they had the highest ecosystem GPP value. Thus, it limited the effectiveness of VI values to capture the magnitude of GPPEC.
# Characterization of Nanoparticle Batch-To-Batch Variability
## 4 Discussion
### Impurities  
* The batches produced by liquid phase synthesis are partly contaminated by low concentrations of metals (e.g., Cu, Al, Mg) which are too low to be of toxicological concern and of which the sources remain unclear but most likely they were present in the starting reagents.
* Silica nanoparticles from flame synthesis have a higher chemical purity than the ones produced by Stober synthesis. Due to the use of smaller amounts of precursors, mostly pure gases, the particles formed in a high temperature process are therefore of higher purity. This is in agreement with recent studies by [PERSON] et al. comparing precipitated synthetic amorphous silica (SAS) with fumed SAS [46].
* The levels of impurities and the main elemental concentrations in water dispersions (TiO\({}_{2}\), CeO\({}_{2}\), Stober silica, polystyrene and ZnO) vary from batch to batch dependent on different synthesis parameters. However, also in batches synthesized in the same way (Stober silica, TiO\({}_{2}\) and ZnO) the composition and amount of impurities varied. Yet, interestingly for ceria produced by the same synthesis route this variability of trace contaminants was largely absent.
* Ca was most often detected as impurity at higher levels. Similar findings were reported by [PERSON] et al. and by [PERSON] et al. for the JRC representative manufactured NMs [45; 46; 47; 48]. The dispersant (water) has been suggested as a potential source.
# An ECC-Based Anonymous and Fast Handover Authentication Protocol for Internet of Vehicles
## 6 Performance Analysis
### Communication Cost
In summary, the total communication overhead of our scheme is 2528 bits. Figure 4 compares the communication overhead of each protocol.
# Using Virtual Soundwalk Approach for Assessing Sound Art Soundscape Interventions in Public Spaces
## 3 Results
### Results of the Qualitative Data Analysis
#### 3.2.2 Soundscape Descriptors  
The mean values of soundscape descriptors are shown in the Figure 5, while the statistical significance in change between the conditions 1 and 2 is shown in the Table 3. The only soundscape in this study characterized as clearly 'negative' would be at the location B. As observed in the Figure 5, the change from the condition 1 to the condition 2 introduced the following general changes in terms of the four quadrants (calm, vibrant, chaotic, and monotonous):  
* less monotonous and calmer and more vibrant at the location A
* slightly less chaotic and calmer at the location B
* less calm and more vibrant at the location C  
As shown in Table 4, the series of rank-based Kruskal-Wallis tests performed for the change in soundscape descriptor values revealed the following results:  
* A2 significantly more pleasant than A1 (\(p\) = 0.0043)
* B1 significantly calmer than B2 (\(p\) = 0.0068)
* B2 significantly more unpleasant than B1 (\(p\) = 0.0032)
* C1 significantly calmer than C2 (\(p\) = 0.0024)
* C2 significantly more exciting than C1 (\(p\) = 0.0004)
# Prestack Seismic Inversion via Nonconvex L\({}_{1-2}\) Regularization
## 6 Conclusions  
In this study, we developed a new method for performing a prestack AVA inversion that relies on nonconvex L\({}_{1-2}\) regularization. In our method, both the construction of the inversion objective function and the decorrelation of the input parameters improve the stability of the inversion results. Additionally, we verified the effectiveness of our new method via synthetic tests and conducting a specific case study with real data. Our L\({}_{1-2}\) prestack AVA inversion method produces P/S impedance results that are more accurate and stable than those generated using the BP inversion method. From our P/S impedance results, we calculated P/S velocity ratios that allowed us to easily identify a target reservoir formation. Although prestack AVA inversion methods are sensitive to noise and the amount and quality of the observational data used in the inversion, our proposed method demonstrates better performance and has a high potential in the detection and identification of fluids.  
Project administration, X.W.; writing--original draft preparation, W.N.; writing--review and editing, F.X. and B.L.; Supervision X.W. and X.N. All authors have read and agreed to the published version of the manuscript.  
This study was financially supported by Chongqing Key Laboratory of Geological Environment Monitoring and Disaster Early-warning in Three Gorges Reservoir Area (No. ZD2020A0501), Open Fund (PLC20211105) of State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation (Chengdu University of Technology), youth project of science and technology research program of Chongqing Education Commission of China(Grant No.KJQN202101226),the National Science Foundation of China (Grant No. 41774142), and the Major National Science and Technology Projects of China (Grant No. 2016 ZX05002-004-013).  
Not Applicable.  
Figure 19: Synthetic vs. actual records for angle gathers of 15\({}^{\circ}\), 30\({}^{\circ}\), and 45\({}^{\circ}\) using (**a**) the L\({}_{1-2}\) inversion method and (**b**) the BP inversion method.  
Figure 18: Synthetic vs. actual records for angle gathers of 12\({}^{\circ}\), 27\({}^{\circ}\), and 42\({}^{\circ}\) using (**a**) the L\({}_{1-2}\) inversion method and (**b**) the BP inversion method.  
Data Availability Statement: The data presented in this study are available on request from the corresponding author. The data are not publicly available due to privacy.  
The authors declare no conflict of interest.
# A Proposal for a Standardized Approach to Inducing Low Energy Availability in Athletes  
[PERSON]  
1 Faculty of Sport, University of Ljubljana, Gortanova 22, 1000 Ljubljana, Slovenia;  
[PERSON]@fsp.uni-ljsi (V.H.); [PERSON]@fsp.uni-ljsi (S.R.)1  
[PERSON]  
2 Department of Sport and Exercise Sciences, Durham University, Durham DH1 3 LY, UK;  
[EMAIL_ADDRESS]  
[PERSON]  
1 Faculty of Sport, University of Ljubljana, Gortanova 22, 1000 Ljubljana, Slovenia;  
[PERSON]@fsp.uni-ljsi (V.H.); [PERSON]@fsp.uni-ljsi (S.R.)1  
[PERSON]  
1 Faculty of Sport, University of Ljubljana, Gortanova 22, 1000 Ljubljana, Slovenia;  
[PERSON]@fsp.uni-ljsi (V.H.); [PERSON]@fsp.uni-ljsi (S.R.)1  
Footnote 1: email: {juvv.h.jv.  
have been proposed; 15 kcal/kg FFM/day [6] and 30 kcal/kg FFM/day [7]. Inability to determine a threshold for LEA in men remains for several reasons. One of these is that men do not exhibit clear clinical signs of LEA such as amenorhea in females [8]. However, more importantly, the methodology for determining EA in either men or women is not universal [9]. Subjective assessment with questionnaires and estimations has proven to be useful [10; 11] but it does not solve the problem of determining the threshold. Neither has it provided any conclusions on which subjective method is the most suitable [9]. Furthermore, different approaches to measuring EA with objective methods (like using accelerometers or heart rate monitors for measuring energy expenditure [12]) add to the problem of comparability of results [9]. This does not help in finding better screening and assessment tools or markers that would provide a reasonably low-cost and low-burden methods for determining LEA. The fact that still no threshold for EA has been determined in men, causes further issues in research in assessing LEA causes/consequences [9].  
In addition to the methodological problems, the duration and possible other factors that propagate LEA are still not known. A systematical approach to inducing LEA in previously healthy athletes is needed to determine a threshold for LEA or to dismiss this hypothesis and determine a range when LEA can occur. This LEA-induced state could more accurately provide conclusions on how long this needs to persist to negatively impact health/performance. A controlled state of induced LEA would also eliminate all possible inaccuracies that occur in assessing EA in free-living athletes. Performing LEA in controlled, \"laboratory-like\" environment, yet in real athletes, would also give relevant information on which markers could be used in future for easier assessment without the long-lasting, high-burden and error-prone objective methodology.  
This is why we propose a two-way standardized, systematic and controlled protocol for inducing LEA in free-living athletes. This protocol should be researched together with plausible health and performance outcomes with objective and subjective methods.