esa-sceva/satcom-chunk-collection huggingface dataset:
# An Analysis of the Altitude Impact on Roots Compressor Operation for a Fuel Cell System
## 1 Introduction
Additionally, especially at very low or very high mass flows (related to low- and high-power demands from the fuel cell), surge and choke limitations can prevent the compressor from reaching such high-pressure-ratio values, depending on the particular compressor technology and design. Few studies in the literature have studied the effects of altitude on the performance of PEM fuel cells. [PERSON] et al. [42] examined the performance of an air-breathing (atmospheric) proton-exchange membrane (PEM) fuel cell at high altitudes. They demonstrated that reduced pressure negatively affects performance primarily due to activation losses, while airflow played a secondary role. Increasing airflow improved performance, particularly at low pressures, highlighting the importance of optimizing air supply for aviation applications. These findings are crucial for designing fuel cells that are effective at high altitudes. [PERSON] et al. [38] explored the performance of PEMFc in aviation and identified notable efficiency losses at higher altitudes due to decreased ambient pressure and lower oxygen levels. They suggested that increasing the air stoichiometric factor can help mitigate this decline. [PERSON] et al. [43] discussed a fuel cell-powered UAV designed for low-altitude surveillance, which could achieve flight times of nearly four hours. It employed a lightweight PEM fuel cell combined with a hydrogen generator. However, the UAV operated at an altitude of 1000 m above ground level, which is lower than the typical surveillance altitudes of around 5000 m. This difference required certain design adaptations to accommodate the effects of lower atmospheric pressure and temperature.
# Optimizing Sustainable Energy Transitions in Small Isolated Grids Using Multi-Criteria Approaches
## 1 Introduction
### Global Energy Transitional Scenario
This study simulates and evaluates the performance of the autonomous renewable generation system of electric power based on Renewable Energy Sources (RESs) such as wind generation and storage technologies (reversal pumping system) with no CO\({}_{2}\) emissions placed in El Hierro island since 2014. In January 2000, the El Hierro Island was designated as a Biosphere Reserve, honoring its exceptional preservation of environmental and cultural richness, alongside its commitment to progress and the welfare of its inhabitants. Under this basis, the project \"Hydro-wind Exploitation of the Island of El Hierro\" [25] was launched. The hydro-wind power plant emerged from this project; it was designed to supply electricity to the island using clean and renewable sources such as water and wind. The wind farm can meet the island's electricity demand at any time. Surplus energy that is not utilized is employed to pump water between a lower and upper reservoir, accumulating it in the latter to generate electricity through hydraulic jumps during periods of low wind. Consequently, this combination of wind and hydro generation transforms an intermittent and unpredictable source, such as wind, into a constant and controlled supply, thus contributing innovative advancements to the renewable energy sector. However, if Gorona del Viento cannot supply enough energy, the diesel-powered power plant at Llanos Blancos comes into operation. Although initial estimations of the system performance were expected to reach almost 75% of the energy coverage through renewable facilities, the system has not been able to reach these figures. In fact, diesel-fired generation continues to account for an average of about 50% of electricity generation during the nearly ten years of operation of the hydro-wind facility.
## 2 Materials and Methods  
### Materials  
The research material was milk and yogurts produced using selected starter cultures enriched with _Bifidobacterium bifidum_. The raw material for the production of yogurts covered by the study was cows' collective milk, which is a mixture of milk from many cows of different breeds (about 45 cows, including 50% Simmental cows and 50% of a mixture of Polish Red and Simmental breeds). The milk was collected from individual producers with farms located in Warmia and Mazury. The milk was purchased in January, it came from cows fed with the cowshed method. The cows were fed with their own production of hay-lage and maize silage (70-80% of the ration) and, triticale, rye, and oat sharps. Additionally, the cows received 1.5 to 2 kg of concentrate for dairy cows. The milk was delivered in a tank to the Technology Hall. Four portions of milk were taken from the delivered milk for the production of yogurts. Two portions of milk were inoculated with the culture starter FD-DVS YC-180 Yo-Flex with BB-12 containing _Lactobacillus delbrueckii_ subsp. _bulgaricus, Lactobacillus delbrueckii_ subsp. _lactis, Streptococcus thermophiles_, and _Bifidobacterium bifidum_ ([PERSON], Hersholm, Denmark), and the two were inoculated with culture YC-X16 and BB-12 containing _Lactobacillus delbrueckii_ subsp. _bulgaricus, Streptococcus thermophilus_, and _Bifidobacterium bifidum_ ([PERSON], Hersholm, Denmark). Analyses were carried out for raw milk, pasteurized milk prepared for the production of yogurts, and manufactured yogurts. The yogurts used for the analyses were produced by the thermostatic method. The production process included the following stages: first, the raw milk was heated to 45 \({}^{\circ}\)C, then subjected to a centrifugation and degassing process (80 kPa; 60 \({}^{\circ}\)C). The milk prepared in this way was then pasteurized using the HTST method (72 \({}^{\circ}\)C/15 s; ALFA-LAVAL P20-HB pasteurizer, Lund, Sweden) and left to cool down to the temperature of 6 \({}^{\circ}\)C (ALFA-LAVAL P20-HB pasteurizer, Lund, Sweden). After the completion of the cooling process, skim milk was added to the milk to standardize the fat content to 2 \(\pm\) 0.1%. The material was then homogenized in a two-stage process (18/5 MPa, 65 \({}^{\circ}\)C; CN003 homogenizer, Spomasz Belzyce, Poland) and then pasteurized in a long-term VHT (Very High Temperature) pasteurization (90 \({}^{\circ}\)C/5 min; ALFA-LAVAL P20-HB pasteurizer, Lund, Sweden). The milk was then cooled to 45 \({}^{\circ}\)C and inoculated with selected starter cultures (powder form) that were pre-incubated for 2 h at 45 \({}^{\circ}\)C in the amount of 1 mL/L of milk. After the production process was completed, the yogurts were packaged into unit-size containers and left to mature in thermostats (Binder GF115, Tuttingen, Germany) for approximately 4 h at the temperature of 43.5 \({}^{\circ}\)C, until they reached pH 4.6. Four samples of yogurts from each production process and each batch were collected for analyses. In total, sixteen samples of yogurt were collected, and their analyses were conducted in two parallel replications.
## 4 Experiments
### Results
#### 4.5.4 Model Complexity Comparison Experiment  
In order to lighten the network, we used depth-separable convolution to replace the ordinary convolution. The Params and FLOPs of the Zero-DCE low-light enhancement network based on the a kernel selection module (excluding the strong light judgment method and the light effect decomposition method) were substantially reduced compared with the original Zero-DCE. As shown in Figure 15, the Params were about 65% of the original and FLOPs were about 60% of the original when the input image size was 1200 \(\times\) 900 \(\times\) 3.
# Correlation Mapping of Perfusion Patterns in Cutaneous Tissue
## 2 Materials and Methods
### Measurement Setup  
To detect perfusion changes, we used a Blackfly(r) S BFS-U3-2855M camera (FLIR Systems, Wilsonville, OR, USA). Simultaneously, we used the SpinView (FLIR Systems, Wilsonville, OR, USA, version 2.5.0.80) to control the camera during measurements. We saved recorded images in a 12-bit.raw format to avoid compression or data loss.  
A two-panel LED illumination emitting white light with a temperature of 5500 K was used as the light source, which according to [PERSON]'s law corresponds to the value of the radiation peak at a wavelength of approximately 527 nm and thus complements the used band-pass optical filter with a central wavelength of (540 \(\pm\) 2) nm and a bandwidth of (10 \(\pm\) 2) nm (Edmund Optics(r), Barrington, NJ, USA). Data were recorded at 30 frames per second with a spatial resolution of 1936 \(\times\) 1464 px\({}^{2}\) with a Fujinon CF12.5 HA-1B fixed focal length lens (Fujifilm Holdings, Tokyo, Japan) mounted on the camera. By default, the aperture value was set to f/2 because of a narrow band-pass optical filter causing light with low-intensity incidents on the sensor. The value is a trade-off between ensuring sufficient intensity of incident light on the sensor and the image's depth of field. The number of recorded frames was 20,000, representing approximately an 11-min-long record.  
The automatic exposure time and signal gain were turned off and set to a static value. The camera gain was set at low values because noise is amplified along with the useful signal. The camera exposure time was set to 32 ms. When setting the exposure time, we were limited by the frame rate (in our case 30 fps), and therefore it was not possible to exceed the value of 33 ms. At the same time, gamma correction was manually turned off.  
To obtain reference signals, we used a BIOPAC MP36R device (BIOPAC Systems Inc., Goleta, CA, USA). With this device, we synchronously acquired the electrocardiogram, respiratory, and pulse wave waveform of the examined patients. The ECG signal was recorded using the Einthoven lead II (BIOPAC SS2 LB shielded cable, F9024 SSC Ag/Cl electrodes). Respiratory activity was acquired with a chest belt placed in the thoracic region (BIOPAC SS5 LB). The pulse wave was measured with an infrared reflectance sensor (BIOPAC SS4 LA). Furthermore, the BIOPAC Student Lab 4.0.3 unit offers predefined settings for individual measurements. The sampling rate of the BIOPAC unit is set to 1000 Hz by default. The layout of the measurement setup is shown in Figure 1.
# Medical Augmented-Reality Visualizer for Surgical Training and Education in Medicine
## 5 Conclusions  
We propose a low-cost glasses-free medical AR visualizer called MARVIS for use in surgical training and education in medicine. The proposed approach allows the projection of internal structures on the surface of a silicone liver phantom considering the user's viewpoint. The system setup prevents problems such as eye strain, discomfort, and fatigue, which are generally present when using AR headsets or glasses. Moreover, marker-less shape matching simplifies the phantom preparation. The overall accuracy of the MARVIS system from the viewpoint of natural human perception is highly satisfactory. Regarding the employed hardware, MARVIS accuracy is in the range of a single pixel of the projected image.  
MARVIS may be used to support the education in medicine and improve the training of surgeons without risk to patients. Using MARVIS, we demonstrated that an AR system can influence the performance to accomplish surgical procedures. Using a real phantom provides a natural tactile experience for future surgeons and can simplify the process of surgical operation planning.  
In future work, we will focus on improving visual data representation and decreasing the system response time to improve the user experience. We also intend to render more complex texture information related to internal structures using computer-generated 3D lighting. Further development of 3D mapping algorithms is also planned.  
Conceptualization, R.G., M.W. and R.S.; methodology, R.G. and R.S.; software, R.G.; validation, R.G., M.W., W.L., and M.K.; investigation, R.G.; resources, L.G.; writing--original draft preparation, R.G. and R.S.; writing--review and editing, M.W.; supervision W.L., M.K., and R.S.; project administration, R.S.; funding acquisition, R.S.  
The work described in this article was part of project 2014/13/B/ST7/01704, funded by the National Science Centre with public money for science and statutory work at Warsaw University of Technology, Poland.  
The authors declare no conflicts of interest.
# Effect of Environmental Temperature on the Insulating Performance of Epoxy/MgO Nanocomposites
## 3 Results and Discussion
### Breakdown Performance
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Percentage** & \(E_{0}\) **(20/150 \({}^{\circ}\)C)** & \(\beta\) **(20/150 \({}^{\circ}\)C)** \\ \hline EP & 32.426 & 16.324 & 16.523 & 12.482 \\
0.5 wt\% & 34.994 & 16.884 & 19.799 & 13.576 \\
1 wt\% & 35.534 & 17.456 & 26.049 & 16.137 \\
3 wt\% & 33.814 & 15.762 & 22.573 & 13.426 \\
5 wt\% & 33.226 & 13.324 & 17.822 & 12.213 \\
7 wt\% & 31.579 & 11.498 & 20.135 & 13.902 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Weibull distribution size and shape parameters of pure epoxy resin and MgO/epoxy composites with different mass fractions. increased their crystallinity. The area of the interface formed between the crystalline and amorphous phase per unit volume increased, increasing the trap density of the composites and the trap energy level. Therefore, the carriers were easily captured during the movement of the electrodes, which hindered the directional movement of electrons to a certain extent. Moreover, the shape parameter of the nano-MgO/epoxy composites was relatively large, which indicates that the dispersion in the polymer was relatively uniform, and the unit cells were closely arranged. As a result, the electron pathway was tortuous and the breakdown field strength was effectively improved. With the increase in the MgO nanoparticle content, the electrical strength of the epoxy resin decreased, because when the composite was doped with a small amount of nanoparticles, the interaction zone formed by the particles and the epoxy-matrix presented no overlap. At this time, the interaction zone can be changed. As an isolated unit, it was difficult for carriers to overcome the barrier to participate in conduction, so the electrical strength increased. When the content of nanoparticles was greater than 1%, the distance between adjacent particles decreased, exceeding the seepage threshold, and the interaction zone overlapped. Consequently, local conductive channels were formed inside the sample. Under the action of the electric field, carriers migrated along these conductive channels, which accumulated a higher energy and collided with the defects in the interaction zone, resulting in the power frequency of the sample. Therefore, the electrical strength was reduced. On the other hand, when no fillers were added to the epoxy resin, defects appeared due to incomplete curing, resulting in a decrease in the breakdown strength. When MgO nanoparticles were added to the epoxy resin, a tight connection was formed between molecules and chains. This connection prevented the movement of initial electrons and brought MgO nanoparticles into close contact with the epoxy resin, eliminating the defects of the epoxy resin itself due to the large specific area of the nanoparticles. Moreover, MgO nanoparticles did not introduce defects, therefore the composites exhibited a higher breakdown strength.
# Methodology for the Prediction of the Thermal Conductivity of Concrete by Using Neural Networks
## 1 Introduction
An ANN is composed of a set of networks of interconnected nodes, which work together to learn complex relationships between a group of inputs and outputs. This makes them well suited for predicting some values based on a variety of parameters. In this way, ANNs can be used to solve problems that conventional or other computational methods have difficulties with [19]. ANNs provide an alternative method for predicting concrete properties that is faster, cheaper, and more accurate than traditional methods. One of the drawbacks typically encountered when developing an ANN is a limited dataset, and effectively training an ANN requires a massive amount of data. When this problem arises, an alternative that has been emerging is the use of a Generative Adversarial Network (GAN). GANs were introduced by [PERSON] et al. [20] and became a revolutionary development in the world of generative modeling. They have different applications, such as image generation, super-resolution imaging, style transfer, and data augmentation. Regarding tabular data, they can create synthetic data to expand real datasets and prevent over-fitting in such data-limited situations, helping to improve the training of an ML model. Although GANs started with image generation, some authors have already used this technique to create tabular data and obtain satisfactory results. Since the introduction of GANs, several algorithms to model tabular data have been used, such as a Conditional Tabular GAN (CTGAN) [21], TabGAN, and CopulaGAN [22]. Although many researchers have attempted to use ANNs to predict different properties of concrete, only a few works are progressing on models to determine the thermal properties. Additionally, the papers do not have a generalist model focusing on different types of concrete, including its many constituents. This work intends to fill this gap, and the novelty is the development of a methodology using an ANN model integrated with a data augmentation model to predict the thermal properties of concrete containing different types of materials such as slag, lightweight and recycled aggregates, fibers, and others. For this methodology, a Multilayer Perceptron (MLP) model to predict thermal conductivity and a Copula GAN model to improve the tabular data from published papers will be developed based on the constituents' composition and the concrete's density. The rest of the paper is organized as follows. Section 2 provides an overview of the ANN used to predict the properties of concrete. Next, Section 3 describes the methodology adopted for this work. Section 4 evaluates the results using a case study and discusses the main findings. Finally, the final section contains concluding remarks on the general findings.
###### Abstract  
With its unique environment and strategic value, the near space (NS) has become the focus of global scientific and technological, military, and commercial fields. Aiming at the problem of communication interruption when the aircraft re-enters the atmosphere, to ensure the needs of communication, navigation, and telemetry, tracking, and command (TT&C), this paper proposes an overall integration of communication, navigation, and TT&C (ICNT) signals scheme based on the K/Ka frequency band. Firstly, the K/Ka frequency band is selected according to the ITU frequency division, high-speed communication requirements, advantages of space-based over-the-horizon relay, overcoming the blackout problem, and the development trend of high frequencies. Secondly, the influence of the physical characteristics of the NS on ICNT is analyzed through simulation. The results show that when the K/Ka signal is transmitted in the NS, the path loss changes significantly with the elevation angle. The bottom layer loss at an elevation angle of 90\({}^{\circ}\) is between 143.5 and 150.5 dB, and the top layer loss is between 157.5 and 164.4 dB; the maximum attenuation of the bottom layer and the top layer at an elevation angle of 0\({}^{\circ}\) is close to 180 dB and 187 dB, respectively. In terms of rainfall attenuation, when a 30 GHz signal passes through a 100 km rain area under moderate rain conditions, the horizontal and vertical polarization losses reach 225 dB and 185 dB, respectively, and the rainfall attenuation increases with the increase in frequency. For gas absorption, the loss of water vapor is higher than that of oxygen molecules; when a 30 GHz signal is transmitted for 100 km, the loss of water vapor is 17 dB, while that of oxygen is 2 dB. The loss of clouds and fog is relatively small, less than 1 dB. Increasing the frequency and the antenna elevation angle can reduce the atmospheric scintillation. In addition, factors such as the plasma sheath and multipath also affect the signal propagation. In terms of modulation technology, the constant envelope signal shows an advantage in spectral efficiency; the new integrated signal obtained by integrating communication, navigation, and TT&C signals into a single K/Ka frequency point has excellent characteristics in the simulation of power spectral density (PSD) and autocorrelation function (ACF), verifying the feasibility of the scheme. The proposed ICNT scheme is expected to provide an innovative solution example for the communication, navigation, and TT&C requirements of NS vehicles during the re-entry phase.  
**Keywords:** K/Ka frequency band; near-space (NS); signal transmission loss; rainfall attenuation; atmospheric loss; integration of communication and navigation; integration of communication (ICNT); navigation and telemetry; tracking and command (TT&C)
## 6 Conclusions and Future Work  
Our cluster-based SFDC framework takes advantage of the structural similarity index to perform the energy-aware wake-up/sleep nodes scheduling scheme by which the spatial correlation is leveraged to save even more energy. Unlike other typical clustering techniques considering the spatial correlation, both of the Euclidean distance and the Pearson's distance are used to be two metrics of the correlation of sensor nodes in our clustering algorithm. With the node scheduling scheme, only a part of nodes in the cluster are required to work for sampling, while the rest of nodes switch to the sleep mode for energy saving. Since the active node selections are based on the features of sampling data changing  
Figure 10: The changing fidelity for the scenario with 1000 nodes during the data collection.  
over time, we dynamically adjust the data collection period against the cluster deterioration to avoid the structure index instability resulted from the change of the inter-node relationships. Simulation results show that SFDC is more suitable for the large scale dense WSNs in order to achieve a better effect on energy saving. Our clustering and node selection algorithms have remarkable advantages in the sleeping node ratio when compared to the random cluster heads and active nodes selection. We also discuss the node contribution rate and provide a way to determine the fidelity threshold in practice. Finally, the adaptive data collection scheme is proved to be an effective technique in response to the spatial correlation changes.  
As future work we intend to explore the temporal correlation to further reduce energy consumption without the decline of structural fidelity. And the data prediction and compression techniques can be exploited and used to achieve the objective. In addition, we will consider the problems of sensor failure and calibration into our data collection framework in future work.  
The work described in this paper was supported by the National Natural Science Foundation of China (No. 61370107, No. 61165007), the Nature Science Foundation of Jiangxi Province, China (No. 20132 BAB211036), the Research Foundation of Education Bureau of Jiangxi Province, China (No. GJJ14367), and the Youth Science Foundation of Jiangxi Province, China (ID: 20122 BAB211022).
# TransECA-Net: A Transformer-Based Model for Encrypted Traffic Classification
## 2 Related Work
### Protocol-Analysis-Based Methods  
[PERSON] [16] and [PERSON] et al. [17] employed Deep Packet Inspection (DPI) to scrutinize both packet headers and payloads, thereby analyzing the distinctive characteristics of specific protocols for classification purposes. This methodology is renowned for its high accuracy and its ability to identify non-standard applications that utilize standard ports. However, it is accompanied by considerable computational overhead and faces challenges in accommodating emerging protocols and encrypted traffic. Furthermore, rising concerns surrounding user privacy have precipitated the gradual decline in the utilization of this approach.