esa-sceva/satcom-chunk-collection huggingface dataset:
# A Low-Complexity Lossless Compression Method Based on a Code Table for Infrared Images
## 4 Proposed Method
### An Improved Huffman Coding Lossless Compression Algorithm  
The probability distribution is concentrated in a small range, we only keep shorter codes with high frequency. However, the above operation will result in out-of-range pixels that are not encoded. The proposed method represents all out-of-bounds pixels by the code with maximum code value. The code \"\(111111111111111\)\" with a maximum code value is used to encode \"\(+151\)\". The improved Huffman coding rules are as follows:  
\[index=\begin{cases}2\times(0-pixel),&\text{if }pixel\leq 0\\ 2\times pixel-1,&\text{if }pixel>0\\ 301,&\text{if }index>300\end{cases}, \tag{7}\]  
The coding rules are shown in Table 7.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Pixel**  
When \(index>300\), let \(index=301\), encode all out-of-bounds pixels with the maximum code value, and we need to create an array \(\vec{B}\) to record the original values of the out-of-bounds pixels in the order in which they appear. Since the probability of an out-of-bounds pixel is extremely small in the whole image, \(\vec{B}\) does not take up much space and has little impact on the compression ratio. When the longest code is decoding, then the out-of-bounds pixels are taken out of the \(\vec{B}\) sequentially so that the differential image can be recovered. The algorithm is described in Algorithm 4 and Figure 6.  
```
0:\(img\_data\),\(\vec{B}\)
0:\(compress\_data\)
1:\(i=1,j=1\)
2:\(\vec{S}=creat\_S(\vec{C})\)
3:\(data1=save\_first\_column(img\_data)\)
4:\(dif\_img\_data=inter\_column\_differencing(compress\_data)\)
5:while\(i\
eq img\_width-1\)do
6:while\(j\
eq img\_height\)do
7:\(pixel=dif\_img\_data(j,i)\)
8:if\(pixel\leq 0\)then
9:\(index=2\times(0-pixel)\)
10:else
11:\(index=2\times pixel-1\)
12:endif
13:if\(index\)>300 then
14:\(index=301\)
15:\(\vec{B}\Leftarrow pixel\)
16:endif
17:\(j=j+1\)
18:endwhile
19:\(bitstream=encoding(\textit{S}\_index)\)
20:\(i=i+1\)
21:endwhile
22:\(compress\_data=save\_date(data1\_bitstream,\vec{B})\)
```  
**Algorithm 4** Lossless compression algorithm for the improved Huffman coding based on a code table.  
For more-bit images, we need to find a new differential pixel range of one-to-one encoding. The new differential pixel range must cover most of the pixels in scenes in order to ensure that the improved Huffman coding is efficient.  
Figure 6: The lossless compression algorithm. (**a**) Coding rules of the improved Huffman coding. (**b**) Framework of the lossless compression algorithm.  
The original image can be recovered from the first column of the original image data and the differential image data. The formula for image recovery is as follows:  
\[p^{\prime}(i,j)=\begin{cases}p(i,1),&\text{if }j=1\\ p^{\prime}(i,j-1)+dp(i,j-1),&\text{otherwise }j>1\end{cases}, \tag{8}\]  
where \(p^{\prime}(i,j)\) is the current column pixel of the recovery image, \(p^{\prime}(i,j-1)\) is the previous column pixel of the recovery image, \(p(i,1)\) is the first column of the original image data, and \(dp(i,j-1)\) is the difference pixel.
# Nozzle with a Feedback Channel for Agricultural Drones
## 4 Result
### Droplet Size  
The distribution of the average droplet size for 1 s in the radial position from the center of the nozzle is shown in Figure 11a. In all cases, the larger droplets are observed at the center of the nozzles. Compared with the proposed nozzle, the commercial nozzle has a sharp peak distribution. The droplet size in the commercial nozzle was reduced to 10% at \(x/D=1.5\). The proposed nozzle has a much smaller droplet size than the commercial nozzle, and the size gradually decreases as the radial position increases. These distributions show that the proposed nozzle can produce a more uniform droplet size over a wider range than commercial nozz.  
Figure 7: Contours of spraying area for (**a**) commercial and (**b**–**e**) proposed nozzle with a load of (**b**) 0 kg, (**c**) 30 kg, (**d**) 40 kg, and (**e**) 50 kg.  
Figure 11b shows the averaged diameter of whole measured droplets that was obtained from each of the droplet area values, with an assumption of spherical particles. The draft potential is the one of the criterion for the nozzle selection. Although the draft is related with many factors such as droplet size, surrounding wind, drone propeller speed, and height of spraying drone operation, the droplet size is the most important for that. Typically, commercial nozzles in agricultural applications have a diameter range of 300-500 \(\upmu\)m, and some operate between 400 and 700 \(\upmu\)m. In addition, [PERSON] et al. [26] reported that a good  
Figure 8: Contour of spraying area at the measured location of 1 in Figure 3 for the developed nozzle with a load of (a) 0 kg, (b) 30 kg, (c) 40 kg, and (d) 50 kg.  
Figure 9: Line profile of spraying amount of the developed nozzle at \(z=5\).  
spray effect can be obtained when the diameter of the spray particles is in the range of 150 to 440 \(\upmu\)m, and the suitable diameter is 250 to 500 \(\upmu\)m, to avoid scattering. The commercial nozzle had a droplet size of 1.70 mm exceeding the suitable range for the sprayer. However, the feedback channel nozzle has a droplet size of 226 \(\upmu\)m for a 30 kg load suitable for agricultural applications. For load conditions of 40 and 50 kg, the diameters are 265 and 280 \(\upmu\)m, respectively, sufficient to prevent scattering. The reduction in droplet size indicates that the proposed nozzle can improve the performance of agricultural drones.
# An Improved Orthogonal Matching Pursuit Algorithm for CS-Based Channel Estimation
## 2 Materials and Methods  
### Wireless Communication System Model Based on CS Channel Estimation  
To eliminate the effects of channel multipath and Doppler on the transmitted signal via channel equalization techniques, an accurate channel state has to be obtained. Block transmission systems based on frequency domain equalization, such as OFDM and SC-FDE, have been extensively applied due to their good compromise between system complexity and performance.
# Review on Mechanisms and Kinetics for Supercritical Water Oxidation Processes
## 3 Kinetics Models and Their Development
### Semi-Empirical Model  
Compared with empirical models, semi-empirical models focus on the intermediates for SCWO of organic compounds, which better reflect the degradation pathways of organics. Some scholars have developed lumped kinetic models, which can not only reflect the changes of organic removal rate, but also better realize the quantitative description of intermediate products in the process of degradation.
## 5 Discussion
For the four class setups, better results were reached with the spectrogram images (test accuracies of up to 87.5%), but with the more complex eight class setups, better results were reached with the scalogram images (test accuracies of up to 91%). It should be noted that, with the scalogram images, a non-decimated signal gives better classification accuracy, while with the spectrogram images, a bigger decimation factor can generate images that give better classification accuracy.
# Real-Time Path Planning of Driverless Mining Trains with Time-Dependent Physical Constraints
###### Abstract  
While the increased automation levels of production and operation equipment have led to the improved productivity of mining activity in open pit mines, the capacity of the mine transport system has become a bottleneck. The optimisation of the mine transport system is of great practical significance to reduce the production and operation cost and improve the production and organizational efficiency of mines. In this paper, we first formulate a multiobjective optimisation problem for mine railway scheduling by introducing a set of mathematical constraints. As the problem is NP-hard, we then devise a mixed integer programming-based solution to solve this problem and develop an online framework accordingly. We finally conduct test cases to evaluate the performance of the proposed solution. Experimental results demonstrate that the proposed solution is efficient and able to generate a train schedule in a real-time manner.  
Keywords:mine railway; train scheduling; mixed integer programming; intelligent transportation system +
Footnote †: journal: Applied Sciences
# A Novel Intelligent IoT System for Improving the Safety and Planning of Air Cargo Operations
## 2 System Description  
The four fundamental parts of the developed system, which is presented in block form in Figure 1, are the ULD that incorporates sensors for monitoring its status and condition, the robotic platform that loads the ULD into the cargo compartment of the aircraft, the remote monitoring and control system (RMC), located inside the ULD, that collects data from the sensors placed on the ULD and transmits them to the fourth part of the system, which is the human-machine interface (HMI), via Wi-Fi. The HMI, via a dedicated application developed for the project, transfers data from the RMC system to the robotic platform during the ULD's loading onto the aircraft up until it is securely locked inside the aircraft's cargo compartment so that the robotic platform can monitor the ULD's locking state at all times. It also allows the captain and the crew members to monitor the status of each ULD loaded on the aircraft during flight.  
Before the loading of a ULD onto an aircraft, a unique ID for this ULD is generated and sent to the HMI. This ID is transmitted via Wi-Fi to the robotic platform carrying the ULD inside the aircraft's cargo area and helps it lock securely in place inside that area. During the loading of the ULD onto the plane, the data received from the sensors are periodically sent to the HMI in the form of a status report. In case of an emergency event, during which an alarm signal must be sent to the HMI to inform the aircraft crew, an additional transmission to the HMI takes place between the periodical transmissions. A processing unit integrated into the RMC performs all data collecting and processing operations. The HMI also offers visualization of data retrieved from the sensors. The RMC system can control three basic operations: (a) structural health monitoring of the ULD, (b) fire and smoke detection, and (c) supervision of the locking status of the ULD. The RMC system architecture is shown in Figure 1.  
The choice of Wi-Fi communication over any other originated from the design choice to use an HMI device that would be capable of creating a wireless network, collecting data from all ULDS, and visualizing the state of all ULDs loaded on the aircraft. The authors found the best choice was for it to be a portable device such as a tablet or a smartphone, which would be able to run an application for collecting data from the ULDs and presenting them to the crew members, host an SQLite database for ULD data local storage, as well as create a wireless network for the ULDs to connect to and send their data. The most popular solution for wireless network implementation on a portable device is currently a Wi-Fi network that many tablets and smartphones can provide right out of the box, with no need for hardware or software add-ons.
## 5 Field Application and Monitoring Analysis
### Project View  
The underground tunnel project of Panyu Square Station of Guangzhou Rail Transit Line 22 has a total length of 262.5 m, and the geographical location of the project is shown in Figure 22. The buried depth of the test tunnel is about 26.5 m, and the size of the excavation section (width \(\times\) height) is 14.9 m \(\times\) 11.95 m. The single-hole double-track horseshoe-shaped composite lining structure is adopted, the quality grade of surrounding rock is grade IV, and the bench method is adopted for construction. The minimum horizontal clear distance between the tunnel and Luojiayong bridge piles is only 2.06 m. There are many complex pipelines and major control structures, such as large hotels and libraries, on the ground. The specific location relationship is shown in Figure 23.  
Figure 23: Surrounding environment of section tunnel project.  
Figure 22: The geographical location of the underground tunnel project in the urban area in Guangzhou, China.  
The design parameters of the primary support of the tunnel are as follows: the longitudinal spacing of the spatial reticulated grid is 1.0 m; and steel mesh diameter is 8 mm, with a spacing of 15 cm \(\times\) 15 cm; the shotcrete grade is C25, and the thickness of the sprayed layer is 35 cm; early-strength mortar bolts diameter is 22 mm, the length is 3.0 m, and the row spacing is 1.0 m \(\times\) 1.0 m. The arch foot and side wall are equipped with 42 mm diameter locking anchor tubes, and the single length is 2.0 m.
# Several Cases for the Validation of Turbulence Models Implementation
## 3 Numerical Method
### Boundary Conditions
#### 3.3.1 Flow Boundary Conditions  
For the subsonic inlet, the four conditions imposed from upstream infinity are the two components of the angle of attack, the total pressure, and the total temperature. The condition imposed from the interior of the domain is the outgoing Riemann invariant, \(u+2c/(\gamma-1)\). For subsonic outlets, only one condition is imposed from downstream infinity, which is a user-specified static pressure. The conditions enforced from the interior of the domain are the entropy; tangential velocity; and the incoming and outgoing Riemann invariants, \(u+2c/(\gamma-1)\) and \(u-2c/(\gamma-1)\), respectively.  
The wall boundaries are either inviscid and viscous wall boundaries. All wall boundaries enforce the no-penetration condition [16]. This is the only condition for inviscid walls. For viscous flows, the boundary conditions consist of the no-penetration and no-slip conditions [17], p. 80.  
Symmetry boundary conditions are used to truncate the computational domain whenever there is a plane of symmetry. Symmetry boundary conditions are also used to simulate a two-dimensional (2D) flow field with a three-dimensional (3D) flow solver, creating what is known as a quasi-3D simulation. There are two conditions that must be satisfied with symmetry boundaries: no-penetration and the zero-gradient of state variables on the planes of symmetry. For this paper, a strong implementation of the zero-gradient condition was enforced, that is, both the boundary state vectors and state vectors on the symmetry boundary had the zero-gradient condition applied [18].
## 4 Conclusions  
In order to remove the radiated noise (during phonation) and the other additive environment noise from the EL speech, an improved spectral subtraction method, multi-band spectral subtraction algorithm is investigated in this study in order to takes into account the non-uniform effect of colored noise on the spectrum of EL speech. Because the over-subtraction factor of each frequency band can be adjusted in the enhancement process, both the objective and subjective test results suggest that a better noise reduction effect was obtained and the perceptually annoying musical noise was efficiently reduced (especially in the high-frequency regions), with little distortion to speech information as compared to the other standard speech enhancement algorithm. Furthermore, the proposed algorithm has strong flexibility to adapt complicated and rigorous speech environment by adjusted the over-subtraction factor of each frequency band.  
Future work on this approach will include the development of time-varying over-subtraction factors for each frequency band based on tracking the characteristics of the input EL signal, such as those used in some wavelet denoising techniques[24]. Furthermore, this algorithm is not consider the fact that the human auditory system has different sensitivities for different frequencies, therefore, the perceptual weighting technique[25] should also be added into the algorithm so that take into account the frequency-domain masking properties of the human auditory system. Continued work in this direction is expected to lead to additional improvement in overall EL speech enhancement.
## 4 Efficient FFT Algorithms
### Modified FFT Pruning  
The FFT pruning algorithm proposed in [64] uses conditional statements. The time taken to execute these conditional statements often exceeds the time saved in reduction of computations. Thus, the algorithm does not yield an efficient FFT implementation in terms of computational time. [PERSON] _et al._[65] proposed a re-indexing algorithm and modified FFT pruning algorithm to avoid using the conditional statements and to reduce the computation time.  
The modified FFT pruning algorithm is based on Cooley-Tukey divide-and-conquer algorithm [66]. The proposed modified pruning algorithm adds the pruning of unnecessary multiplication and addition operations, to the Cooley-Tukey algorithm in order to reduce the execution time. In this algorithm, first the matrix \(M_{i}\) similar to the one in [64] is generated and based on which another matrix \(M_{\text{index}}\) is constructed. The matrix \(M_{\text{index}}\) consists of indices and the total number of nonzero elements in each column of matrix \(M_{i}\). The proposed algorithm uses the information provided by \(M_{\text{index}}\) to prune unnecessary computations. Using the simulation results it was shown that, the modified FFT pruning algorithm results in significant reduction in the mean execution time for calculating the FFT as compared to the conventional Cooley-Tukey algorithm for the sparseness factor of 60% or higher.
# A Novel Protocol Using Captive Portals for FIDO2 Network Authentication +
## 8 Future Work  
In this paper, we proposed FIDO2 CAP, and validated it with a real prototype and users. Here, we include some of our current research lines that continue the work we presented in this paper:  
1. **Validate the usability of the solution with more users and compare different samples**. Design new environments and validate user acceptance with different users.
2. **Extend the prototype for auto-registration and validate its usability**. Test the usability of users registering their own credentials in the captive portal for authentication.
3. **Compare the usability of the developed captive portal and a captive portal based on passwords**. Evaluate how passwordless authentication with security keys is more usable than passwords.
4. **Study the usability issues caused by the error management of web browsers with WebAuthn**. We detected some differences when managing exceptions during a failure in WebAuthn authentication. We are working on a study of the current browser implementations and proposing a solution, which can help to improve the usability and adoption of this authentication method.  
Conceptualisation, M.R.-D.; methodology, M.R.-D. and J.V.-N.; software, M.R.-D.; validation, M.R.-D.; formal analysis, M.R.-D.; investigation, M.R.-D.; resources, M.R.-D., A.P. and [PERSON]; data curation, [PERSON]-D.; writing--original draft preparation, M.R.-D.; writing--review and editing, [PERSON] and [PERSON]; visualisation, [PERSON]-D., M.G., A.P. and [PERSON]; supervision, M.G., A.P. and [PERSON]; project administration, [PERSON]-[PERSON] and [PERSON]; funding acquisition, A.P. All authors have read and agreed to the published version of the manuscript.  
This work was founded by EU and \"Xunta de Galicia\" (Spain), grant ED431C 2022/46-Competitive Reference Groups GRC. This work was also supported by CITIC, funded by \"Xunta de Galicia\" through the collaboration agreement between the \"Conselleria de Cultura, Educacion, Formacion Profesional e Universidades\" and the Galician universities to strengthen the research centres of the \"Sistema Universitario de Galicia\" (CIGUS). Also, the work is founded by the \"Formacion de Profesorado Universitario\" (FPU) grant from the Spanish Ministry of Universities to [PERSON] (Grant FPU21/04519).  
Not applicable.  
The developed prototype can be found in Github, published as Open Source: [[https://github.com/martinord/fido2](https://github.com/martinord/fido2) cap-server]([https://github.com/martinord/fido2](https://github.com/martinord/fido2) cap-server) (accessed on 23 April 2024).  
Authors [PERSON] and [PERSON] are partners of the company IKERDATA S.L. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
## 4 Experiments and Evaluations
### Experimental Methods  
Based on the aforementioned purpose, this study used both malicious and white-hat worms and varied the parameters of the white-hat worms to determine whether the white-hat worms could eliminate malicious botnets and how each parameter affected the elimination of the malicious botnet. In this experiment, we investigated the parameters that can eliminate malicious botnets by changing the number of white-hat worms scanned per attempt \(n\) and the lifespan \(\ell\), respectively. We conducted experiments with a total of nine patterns by changing the number of white-hat worms scanned per attempt \(n\) to 50, 100, and 160, and the lifespan \(\ell\) to 60, 180, and 300, respectively. As mentioned, the number of devices scanned per attempt in Mirai and malicious worms \(n\) is 160. In order to clarify that the results obtained by the experiments were independent of the number of vulnerable devices, the experiments described in this paper were conducted with 10 and 30 vulnerable devices, respectively, with the values of the nine patterns of parameters described above.