esa-sceva/satcom-chunk-collection huggingface dataset:
## 2 Numerical Methods
### Simulation setup  
A simple two-step reaction model is used in the present study. Detonations with different instability factors can be obtained by keeping \(k_{\rm I}\) constant but changing \(k_{\rm R}\). As proposed by [PERSON] [33], the activation energy \(E_{\rm I}/RT_{s}=4.8\) and \(E_{\rm R}/RT_{s}=1.0\) to represent hydrogen-oxygen mixtures rather than heavy hydrocarbon mixtures. The specific heat ratio \(\gamma\) is set as 1.44 for all cases. The detonation velocity \(M_{\rm cj}=5.6\). The instability factor \(\chi=E_{\rm I}\Delta_{\rm I}/\Delta_{\rm R}\) proposed by [PERSON] [33] is used to characterize the chemical sensitivity to temperature perturbations. Three detonations with different stability factors were used in the present study, as shown in Table 1. The ZND structures for the three detonations with different instability factors are also shown in Figure 1. The computations are initialized by the steady solution of the ZND detonation. The length and width of the computation domain are \(1600\Delta_{\rm I}\) and \(300\Delta_{\rm I}\), respectively. The left and right boundaries are both set as outflow conditions. The upper and bottom walls are set as slip wall conditions. Artificial temperature perturbations are placed to generate inhomogeneity. The wavelength of the perturbation \(s\) is set as 10 \(\Delta_{\rm I}\), 20 \(\Delta_{\rm I}\), 40 \(\Delta_{\rm I}\), respectively. The amplitude is \(A\), with an average temperature of 295 K, as shown in Figure 2.  
Figure 1: Steady structures of ZND detonations with different instability factors.
# Transformer Fault Diagnosis Method Based on SCA-VMD and Improved GoogLeNet
## 4 Tests and Analysis of Results
### Data Preprocessing and Sample Set Construction  
After the initial data sample set was obtained using simulation tests, the data were further preprocessed using SCA-VMD. When performing the periodic map spectrum generation, the Hanning window was selected as the FFT window to ensure the balance of frequency resolution and time resolution.  
Figure 7 shows the frequency energy curves and feature maps of each mode of the sample data of transformer fault modes under the four different operating conditions after preprocessing. The following operating conditions were numbered 0-3 in turn. As can be seen from the figure, the periodic pattern spectrum feature map generated using SCA-VMD clearly shows the differences between different types of faults and contains a large number of harmonic components, and the frequency of the harmonic components of each fault state was different, indicating that the selection of periodic pattern spectrum feature map as the basis for transformer fault diagnosis was reasonable and feasible.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Methods**} & \multirow{2}{*}{\begin{tabular}{c} **Average** \\ **Iteration Time (s)** \\ \end{tabular} } & \multirow{2}{*}{\
\begin{tabular}{c} **Number of** \\ **Iterations** \\ \end{tabular} } & \multicolumn{2}{c}{**Minimum**} & \multirow{2}{*}{
\begin{tabular}{c} **Standard** \\ **Deviation** \\ \end{tabular} } \\  & & & & \\ \hline PSO-VMD & 19.0 & 14 & 7.390 & 0.176 \\ GA-VMD & 26.7 & 15 & 7.412 & 0.128 \\ SCA-VMD & 13.5 & 7 & 7.323 & 0.127 \\ \hline \hline \end{tabular}
\end{table}
Table 4: Performance comparison of different algorithms under normal operating conditions.  
Figure 7: _Cont._
# Internet of Bikes: A DTN Protocol with Data Aggregation for Urban Data Collection
## 7 Performance Evaluation of IoB-DTN and IoB Long-Range
It is interesting to notice that IoB has better throughput when the duty cycle is small, whereas IoB-LR offers a higher throughput when the duty cycle is high. In fact, these results are related to the packet sizes transmitted in each simulated scenario. We remember that the packet sizes, with SF7, chosen for IoB-LR with SB-LDC and LB-LDC cases are higher than the packet size of IoB. In Figure 22, we also present the average throughput for IoB-LR with the respect of the maximum theoretical duty cycle allowed by LoRa technology. We observe that IoB offers the best throughput than IoB-LR that respects the theoretical duty cycle in all simulated scenarios. Figure 22 shows the average throughput for IoB-LR when respecting the effective duty cycle. It corresponds to the real duty cycle of the bicycles in each scenario. It is shown in Figure 23 and is computed as follows:  
\[EDC=\frac{NPS*Rt}{\sum(Ta-Td)} \tag{4}\]  
where \(EDC\) represents the effective duty cycle; \(NPS\) is the number of sent packets; and \(RT\) corresponds to the airtime defined in seconds. We take for example the case for SB-SDC, the duty cycle should be  
Figure 21: Average consumption background per bike. 20% as mentioned before. On the other hand, its real duty cycle is \(\sim\)16%. Hence, it is important to point out that IoB-DTN protocol provides better throughput than IoB-LR and IoB-LR respecting the theoretical and the effective duty cycle. In the next section, we propose a solution for IoB-DTN protocol in order to improve its performance on energy consumption.
## 3 Tilt and Deformation of Alidade Caused by Track Unevenness  
Experimental measurements were conducted to quantify the tilt and deformation of the alidade induced by track unevenness, while the antenna was rotating in azimuth (AZ) at a constant speed of 0.1 \({}^{\circ}\)/s from AZ 0\({}^{\circ}\) to AZ 360\({}^{\circ}\). The inclinometer's sampling rate was set to 1 Hz, and the test was conducted on a windless night to eliminate temperature gradient interference. To verify the measurement system's repeatability, the experiment was performed three times in succession, yielding results as shown in Figure 11.  
Figure 11 depicts the unfiltered raw data, which exhibits excellent repeatability in tilt meter measurements. This further validates the effectiveness of the inclinometer environment control system in mitigating external temperature drift-induced noise. The peaks observed at 0\({}^{\circ}\) and 360\({}^{\circ}\) are attributed to the antenna moment of inertia when starting and stopping, rather than noise. Table 3 presents the RMS values of antenna pointing errors in both elevation (EL) and azimuth (AZ) directions, which are derived from inclinometer measurement data using Equations (1) and (2).  
\begin{table}
\begin{tabular}{c c c} \hline \hline  & **X Direction** & **Y Direction** \\ \hline First night & 0.51\({}^{\prime\prime}\) & 0.56\({}^{\prime\prime}\) \\ Second night & 0.83\({}^{\prime\prime}\) & 1.32\({}^{\prime\prime}\) \\ Third night & 0.33\({}^{\prime\prime}\) & 0.52\({}^{\prime\prime}\) \\ \hline \hline \end{tabular}
\end{table}
Table 2: The RMS values of the three-night inclinometer measurements.  
Figure 11: The measurement repeatability of three rounds: tilt in AZ and EL direction.  
The table reveals that the track unevenness exerts an \(11.3^{\prime\prime}\) impact on the antenna's EL direction and an \(11.8^{\prime\prime}\) effect on its AZ direction. It is worth noting that, in actual astronomical observations, some of the pointing errors caused by orbit have been compensated by the pointing model.
# Long-Term Behavior of Concrete Containing Wood Biomass Fly Ash
## 4 Conclusions  
This paper presents the results of long-term tests on concrete made with two types and two proportions of WFA as a substitute for part of the cement. The influence of the properties and composition of WFA on the compressive strength, permeability, and shrinkage of the concrete was analyzed over a period of one year. The following conclusions can be drawn from the experiments:  
* Depending on the type of WFA, the 15% WFA content reduced the 28-day strength of the concrete by 6 to 14%, while the long-term strength was reduced by 8 to 17%.  
Figure 8: Detrimental cracking of a cylindrical concrete specimen with 30% wood fly ash (as a cement replacement) containing 57.6% CaO (results of a previous study [82]).  
* At 30% WFA, the compressive strength at 28 days of age was 25 to 37% lower compared to the reference mix.
* When testing the drying shrinkage of the mixes during more than one year, a significant decrease in shrinkage was observed in the mixes with 30% WFA compared to the reference mix, but in the case of WFA2, the swelling deformation was also pronounced at an early age, which was probably caused by a significant amount of free MgO and free CaO; the TG analysis showed that the mixes with WF2 contained brucite, which can also partially cause the increase in the initial volume.
* WFA1, at a 15% content, unlike WFA2, did not have a large contribution to shrinkage reduction compared to the reference mix.  
The potential application of high CaO WFA as a shrinkage reducing admixture requires the determination of the optimum dosage of WFA to minimize the shrinkage and strength decrease. According to the results presented in this work, this could be around 15% of cement replacement. For future applications, it would be useful to know the relationship between storage time and chemical composition of WFA.  
Conceptualization, methodology, formal analysis, investigation, I.G., N.S. and M.S.; Writing--original draft preparation, I.G.; Writing--review and editing, I.G., M.S. and N.S.; Visualization, I.G.; Project administration, N.S.; Funding acquisition, N.S. All authors have read and agreed to the published version of the manuscript.  
This research was performed as part of the research project IP-2016-06-7701 Transformation of Wood Biomass Ash into Resilient Construction Composites', which was funded by the Croatian Science Foundation.  
Not applicable.  
The authors declare no conflict of interest.
###### Abstract  
In this study, we compared the physicochemical properties and the antioxidant capacities of black and green pepper. Green pepper from India (GPI) and Sri Lanka (GPS) had higher Hunter L* and b* values and lower a* values than black pepper from India (BPI) and Sri Lanka (BPS). The contents of chlorophyll a and b, flavonoids, and phenolic compounds in GPI and GPS were higher than those in BPI and BPS. The pepperorms showed the following decreasing order of 2,2-diphenyl-l-picrylhydrazyl and 2,2-azino-bis-3-ethylbenzothazoline-6-sulfonic acid radical scavenging capacities: GPI \(>\) GPS \(>\) BPI \(>\) BPS. High-performance liquid chromatography showed that the highest piperine content was present in GPI (8613.27 \(\pm\) 45.86 mg/100 g). We further investigated the anti-inflammatory capacity of the green pepper. GPS and GPI significantly suppressed lipopolysaccharide-induced nitrite production and inducible nitric oxide synthase expression without being cytotoxic to RAW 264.7 cells. GPS and GPI also suppressed the LPS-induced phosphorylation of mitogen-activated protein kinases, but not p65. GPS had a higher inhibitory effect on LPS-induced c-Jun phosphorylation and translocation from the cytosol to the nucleus than GPI. Thus, the findings of our study suggest that green pepper has the potential to be an effective nutraceutical against oxidative and inflammatory stress.  
g remark  
Green pepper; antioxidant; anti-inflammation; nutraceutical; piperine; mitogen-activated protein kinases (MAPKs)
# Using AI to Improve MIMO Antennas with SRR for 26 GHz by Analyzing Data
## 4 Discussion and Future Opportunities
Furthermore, small but unmodeled fabrication imperfections or non-ideal environmental conditions could lead to discrepancies between predicted and actual performance. The ML model also assumes that the relationships between geometric parameters and electromagnetic behavior remain consistent across designs, which might not hold in highly non-linear or unanticipated scenarios. Future work will include transfer learning and active learning strategies to enhance generalizability, as well as uncertainty quantification methods to better capture the model's confidence in each prediction.
## 4 Experiment Investigation
### The ETRM  
In this experiment, a typical broadband chirp signal is emitted at PZT A. The equation for the excitation signal is,  
\[s_{c}(t)=\sin(2\pi f_{0}t+\frac{\pi Bt^{2}}{T}), \tag{15}\]  
where,\(f_{0}\) is the starting frequency, \(B\) is the chirp bandwidth and \(T\) is the duration of the chirp signal. Here,\(f_{0}\) takes 10 kHz, B = 600 kHz-10 kHz = 590 kHz, and \(T\) takes 1 ms. Figure 7 gives the response signal received at PZT B as the blue solid line.  
STFT, where the window function takes a Gaussian function with time duration of 0.07 ms, is applied to map the response signal into the time-frequency domain. The STFT spectrogram is shown in Figure 8a. To extract the direct wave components of A0 mode from the response signal, the spectrogram outside the two red dashed lines (as _weight_ takes 0.2) is set to zero (Figure 8b), and then the inverse STFT is applied to reconstruct the residual signal. The time domain waveform of the reconstruct direct wave of A0 mode is shown in Figure 7 as the dotted red line.  
Figure 6: Damage index (DI) values change with (**a**) _weight1_ and (**b**) _weight2_ in the health and damage condition.  
Figure 7: The broadband response signal and the extracted direct wave of A0-mode Lamb wave.  
Subsequently, the reconstructed signals related to different narrowband excitations could be calculated using Equation (14). For instance, Figure 9a shows the calculated reconstructed signals with different excitation parameters, i.e., five-cycle toneburst, with central frequencies of 40 kHz, 50 kHz, 60 kHz and 70 kHz, respectively. Figure 9b displays the calculated reconstructed signals with a 40 kHz toneburst excitation with cycle numbers 3, 5, 7 and 9, respectively. These demonstrate that the ETRM has the merit of high efficiency.  
Furthermore, to investigate the influence of _weight_ value on the performance of damage detection, different _weight_ values (0.1, 0.2, 0.3, 0.4 and 0.5) are used for time-frequency filtering. To ensure consistency, narrow-band excitation with the same parameters as in Section 5 is used in this experiment. Figure 10 gives the DI values with the increase of _weight_. It can be seen that though the DI values vary with the _weight_, their values at damaged case keep above the ones at healthy condition. Besides, the relative deviation of DI values in the health and damage conditions at different _weight_ values (i.e., 0.1, 0.2, 0.3, 0.4 and 0.5) are 68.87%, 73.68%, 75.72%, 65% and 76.12%, respectively. It means that the _weight_ value has less influence on the result of damage detection.  
Figure 8: The short-time Fourier transform (STFT) spectrogram of (**a**) the response signal and (**b**) the filtered direct wave of A0 mode.  
Figure 9: Reconstructed signals to (**a**) five-cycle, Hanning windowed tone bursts at various central frequencies 40 kHz, 50 kHz, 60 kHz and 70 kHz and (**b**) 40 kHz Hanning windowed tone bursts with various pulse numbers 3, 5, 7, 9 as generated by the ETRM.
# Intelligent Reflective Surfaces for Wireless Networks:
## 5 Practical Challenges, Open Issues and Future Research Lines
### Open Issues and Future Research Directions
#### 5.2.2 Hybrid Transceivers for mmWave IRS-Assisted Systems  
To reduce the high power consumption and the radio frequency (RF) cost in mmWave MIMO systems, the hybrid analogue-digital architectures have been proposed. The precoder/combiner design in these schemes usually leads to a constrained optimization problems. The IRS technology is well-suited for the mmWave band due to the promising advantages offered in terms of increasing the spatial diversity. The joint optimization of the hybrid precoder/combiner for mmWave MIMO and the IRS phase shift-matrix--which can be seen as an analogue precoder/combiner--constitutes a challenging open problem.  
In [95], an IRS-assisted downlink mmWave MIMO single-user and multi-stream system with hybrid precoding/combining and NLOS conditions has been approached. The authors focus on maximizing the SE by jointly optimizing the IRS phase-shift matrix and the hybrid transceiver. A manifold optimization-based algorithm is developed by exploiting the structure of the mmWave channel. Although this work is interesting, more complex scenarios can be addressed by considering multiuser and wideband scenarios where the transceiver design is more challenging since the analogue part is frequency flat and common to all the users, not to mention the impact of the beam squint effect present in wideband systems.
# Evaluation of Modern Internet Transport Protocols over GEO Satellite Links
## 7 Conclusions  
The performance of modern HTTP variants was evaluated over satellite links using a realistic DVB-S2/RCS emulation testbed. We utilized the full-stack software implementation of HTTP/2 and HTTP/3 to study their performance with BBR and Cubic congestion  
Figure 13: Average PLT of multi-object web page in a satellite link.  
control algorithms. We considered both simple and complex web pages to uncover the interaction of HTTP with the underlying transport mechanism. For this, we studied multiple user-level performance metrics such as page load time and other page rendering measures such as the FCP and LCP which quantify the perceived visual rendering time of page elements. The evaluation revealed the issue of protocol overhead affecting HTTP/2 and HTTP/3 and how it interacts with the congestion control algorithm in large RTT links. In particular for HTTP/3, the problem becomes more significant when using a loss-based congestion control algorithm such as CUBIC which is widely used on the Internet. The results also suggest that HTTP/3 over QUIC will perform better than HTTP/2 and HTTP/1.1 in satellite links specifically with a more aggressive congestion algorithm such as BBR. Finally, the study revealed a negative interaction between the Cubic slow-update cycle and the protocol overhead in HTTP/3 in both low-latency and high-latency links. This issue is worth further investigation since Cubic is currently the most widely used congestion algorithm on the Internet today.  
Conceptualization, A.A. and A.M.; methodology, A.A.; software, A.A.; validation, A.A. and A.M.; formal analysis, A.A.; investigation, A.A.; resources, A.A.; writing--original draft preparation, A.A.; writing--review and editing, A.M.; visualization, A.A.; supervision, A.M. All authors have read and agreed to the published version of the manuscript. This research received no external funding  
The authors declare no conflict of interest.  
The following abbreviations are used in this manuscript:  
\begin{tabular}{l l} PLT & Page Load Time \\ LCP & Largest Contentful Paint \\ FCP & First Contentful Paint \\ QUIC & Quick UDP Internet Connections \\ DVB & Digital Video Broadcasting \\ BER & Bit Error Rate \\ \end{tabular}
## 4 Cryptographic Algorithms
### SHA3-512  
A cryptographic hash function is a mathematical algorithm that maps \"message\" data of arbitrary size to a bit array of a fixed size \"digest\" output message. It is a one-way function and it is practically infeasible to invert or reverse the computation to obtain the original message, except for brute-forcing it. SHA-3 [41] is the latest member of the Secure Hash Algorithm family of standards by NIST, with the predecessors being SHA-2 and SHA-1. The NIST defined four instances in the SHA-3 standard for different digest lengths, including SHA3-224, SHA3-256, SHA3-384, and SHA3-512.  
SHA-3 is a sub-set of a broader cryptographic primitive family called Keccak and is based on a new design approach called sponge construction, which is a comprehensive collection of random functions or permutations. This allows inputting, or \"absorbing\", any amount of data and outputting, or \"squeezing\", any amount of data. Figure 6 below describes the sponge construction in the SHA-3 hash functions.  
In Figure 6, for SHA3-512 to output 512 bits of digest, the input message in the form of a bit string \(N\) was padded using the _pad1041_ pattern padding functions to a multiple of 576 (bits), which is called the rate, denoted as \(r\). The \(c\) is called the capacity and the state of SHA-3 is defined as a bit string with the length of \(b=r+c\), containing all zero bits in it at the beginning. The \(c\) value in SHA3-512 is 1024 (bits), which makes \(b\) 1600 (bits). The padded input is then \"absorbed\" and fed into 24 rounds of block transformation \(f\), which is _Keccak[1024](\(M\mid\mid\) 01, 512)_. The number of \"absorbing\" times is dependent on the length of the input, specifically, the number of 576-bit segments of the padded input. For example, if the input bit string message is 500 bits, then it will be padded to the length of 576 bits, and only one \"absorbing\" operation will be needed. In the \"squeezing\" stage, segments with the length of \(r\) are collected to the bit string \(Z\) until the number of output bits is met, which is 512 bits for SHA3-512. \(Z\) will then be truncated to the output length, and will then be the digest of the message, completing the hash operation.  
Figure 5: The indexed representation of the 4 \(\times\) 4 matrix state S, ranging from 0 to 15.  
Figure 6: The sponge construction, SHA-3 standard: permutation-based hash and extendable output functions.  
A small note on SHA-3 is that it is not considered as a lightweight hash function, and the standardization publication from NIST does not address this either. However, there have been some works [42] on lightweight cryptographic algorithms implemented based on the sponge construction and instances of Keccak, which are parts of SHA-3. The SHA3-512 hash function accelerator core was integrated into the SoC to diversify the type of algorithms that can be applied.
# An Enhanced Non-Coherent Pre-Filter Design for Tracking Error Estimation in GNSS Receivers
This paper proposes an enhanced non-coherent pre-filter design and comprehensively evaluates the performance of coherent pre-filter, non-coherent pre-filter, and traditional discriminator. This paper is organized as follows: Section 2 provides the necessary basic knowledge about tracking error estimation, including the relevant baseband signal model, ATAN/ATAN2/NC-EMLE discriminator algorithms, and coherent/non-coherent pre-filter design. After that, Section 3 puts the emphasis on the observation noise statistics analysis and fault detection and exclusion (FDE) structure when designing the non-coherent pre-filter. In Section 4, four experiment scenes are designed to comprehensively evaluate the performance of enhanced non-coherent pre-filter. The performance of the enhanced non-coherent pre-filter is compared with that of the ATAN/ATAN2/NC-EMLE discriminator and coherent pre-filter to show the improvements. The best working conditions for the discriminator, non-coherent pre-filter, and coherent pre-filter are also analyzed in this section. Finally, Section 5 gives the conclusions and future work.