esa-sceva/satcom-chunk-collection huggingface dataset:
# GIS-Based Flood Assessment Using Hydraulic Modeling and Open Source Data: An Example of Application
## 4 Discussion
### Study Limitations and Future Research Directions  
The research presents several limitations, such as the exclusive focus on steady flow scenarios, which do not capture the complex dynamics of flash floods and unsteady flows; the modeling assumes the presence of protective dikes without analyzing the impact of their potential failure due to the lack of hydrological data, the study does not comprehensively integrate the long-term impacts of climate change or the effects of anthropogenic activities, such as urban expansion or land use changes, which may influence the hydrological regime.  
When applying the findings to other similar studies, the accuracy and precision of the DEM data and hydrological data used are critical, as they can generate potential processing errors and affect hydro-geomorphological analysis.  
Future research perspectives include expanding the applicability of the methodology to other river basins to validate its reproducibility and adaptability. The integration of unsteady flow scenarios and the use of 2D or 3D modeling can provide a more detailed understanding of flood dynamics. Additionally, long-term projections that include the effects of climate change on the hydrological regime could contribute to a deeper understanding of future risks. Technological advancements enable the use of high-resolution satellite data and artificial intelligence to improve the accuracy of floodplain analysis and mapping. Furthermore, assessing existing protective infrastructure and simulating alternative solutions, such as expanding buffer zones or restoring wetlands, is essential for effective risk management. A multidisciplinary approach that integrates ecological, economic, and social perspectives can support the development of sustainable strategies to reduce the impact of floods on communities and the environment.
# Parametric Simulations on Leakage and Performance of a Miniature Free-Piston Generator (MFPG)
## 1 Introduction
Some theoretical analyses on the leakage and heat transfer of miniature heat engines have been carried out [38; 39; 40; 41; 42; 43]. [PERSON] et al. [38] pointed that the leakage gap is essentially the same regardless of the engine size. It is mainly determined by the fabrication tolerance, which is around 10-20 \(\upmu\)m. The gas leakage per cycle is two orders of magnitude higher than that of conventional internal combustion engines (ICEs) because there are no piston rings between the piston and the cylinder wall in micro ICEs. [PERSON] et al. [37] fitted [PERSON]'s analytic simulation with a leakage discharge coefficient of 0.12, then argued that their work exaggerated the leakage by not considering the sealing effect of lubricant oil. Instead, they proposed a smaller value of 0.06 and reasonably reproduced their own experimental cylinder pressure. [PERSON] et al. [40] stated that leakage loss becomes very important when the size of the micro-heat engine is smaller than 20 W. Various solutions are proposed for different prototypes, including the usage of sealing parts and lubricant [41], adopting more advanced bonding technology for the sandwich structure [36], applying liquid piston structure [42] and improving the fabrication technology to reduce the gap width [43]. Heat loss is another major factor leading to inefficiency or flame extinction of micro-engines [44; 45; 46]. As the engine dimension shrinks, the area-to-volume ratio increases, resulting in greater heat transfer loss per unit volume. [PERSON] et al. [46] carried out many tests on the extinguishing distance of propane/oxygen mixture in order to determine the suitable combustion chamber size. [PERSON] et al. [40] simulated the heat loss of a miniature reciprocal ICE, and determined the cylinder wall temperature required to limit the heat loss under 20% and 30% of the total heat released by fuel combustion at different scales. Attracted by the advantages of the free-piston scheme, a single-piston miniature free-piston generator (MFPG) prototype, which directly converts hydrocarbon fuel into electricity, is proposed in this work. The prototype is constructed by combining a miniature internal combustion engine (ICE) with a compatible voice coil motor (VCM). To better understand the influence of leakage and heat transfer on the efficiency of this MFPG, a dynamic model, including heat transfer and leakage sub-models, was established and the parametric study of leakage and its effects on the performance of the MFPG were performed. The energy conversion in the MFPG prototype is also investigated by analyzing the transient power flow among each component force. This study provides a theoretical analysis for the subsequent system optimization.
# Multimode Guided Wave Detection for Various Composite Damage Types
## 4 Detection of Various Damage Types Using ABT-ABT on a 3-mm Quasi-Isotropic Composite Plate
### Pure Mode Generation
#### 4.2.2 Pure SH0 Mode Generation  
The ABT-ABT was used to excite a pure SH0 mode in the 3-mm quasi-isotropic CFRP composite plate. For the excitation of pure SH0 mode at 500 kHz, the incident angle was set to 48\({}^{\circ}\). The same pitch-catch experiment was repeated to collect the response signals at various locations at a constant interval of 10 mm.  
The response signals at five different locations were measured, as shown in Figure 19a. The TOF of the direct wave packet was calculated and plotted as a function of distance, as shown in Figure 19b. Similarly, linear regression was used to estimate the group velocity, yielding a value of 3.49 mm/us, which agreed with the theoretical SH0-mode group velocity of 3.39 mm/us at 500 kHz in the 3-mm quasi-isotropic composite plate. Therefore, the excited guided wave in the quasi-isotropic CFRP composite plate was in pure SH0 mode, as expected. The experimental results demonstrated that the ABT-ABT could successfully generate pure S0 mode and SH0 mode guided waves in the 3-mm quasi-isotropic composite plate.  
In order to demonstrate the feasibility of this technique for damage detection over a long distance, a pitch-catch experiment was conducted on the 3-mm quasi-isotropic CFRP composite plate using the ABT-ABT. The long-distance experimental setup is shown in Figure 20. The distance between the transmitter ABT and the receiver ABT was 350 mm. The measured signal at a 350-mm distance is displayed in Figure 21. Figure 21a shows the time-domain signal, and the short-time Fourier transform (STFT) spectrogram is given in Figure 21b. From the time-domain signal, it was observed that a strong SH0-mode signal was measured even at a far distance of 350 mm using the ABT-ABT. A strong SH0-mode wave packet was also observed in the STFT spectrogram, as shown in Figure 21b.  
Figure 19: Experimental group velocity measurements for the SH0 mode excitation at 500 kHz on a 3-mm quasi-isotropic composite plate: (**a**) waveforms; (**b**) correlation between distance and TOF.
## 3 Codewords Analysis  
In this section, we characterise the codewords of LDPC-CCs into two categories, _i.e._, structured and non-structured. The non-structured codewords can be eliminated by appropriately choosing the power of the monomials or polynomials in \(\textbf{H}^{T}(D)\), while the number of the structured codewords is relevant to the size of \(\textbf{H}^{T}(D)\). The main contribution of this paper is introducing an approach to reduce the number of low weight non-structured codewords so as to improve the distance spectrum for the design of practical LDPC-CCs.
# NMR and LC-MS-Based Metabolomics to Study the Effect of Surfactin on the Metabolome of Flax
## 3 Results and Discussion
### Metabolite Changes in Root
The implication of cyanogenic glycoside levels in plants has already been described in plant stress resistance mechanisms, especially when submitted to herbivore attack [35; 36], and in flax when submitted to abiotic stress [19]. relatively important delay to induce metabolic change in the content of this lignan [19]. Another phenolic compound had a lower content in the surfactin-treated roots at the two kinetic points, namely 4-caffeoylquinic acid.
# Quantum-Key-Distribution (QKD) Networks Enabled by Software-Defined Networks (SDN)
## 5 Three-Use Cases in QKD Networks  
Future QKD networks will gradually transform from \"point to point\" to \"multi-point interconnection\" to achieve end-to-end secret-key provisioning services, which has a full potential for the application of quantum-secure communication. However, QKD networking for multi-point interconnection needs to meet the characteristics required for a series of networking functions. Thus, there are three issues which need to be addressed: firstly, how to efficiently and flexibly allocate multi-dimensional resources in QKD networks? Secondly, how to construct QKP to complete the dynamic on-demand distribution with limited wavelength resources? Finally, how to guarantee the reliability of QKD networks? The available solutions of these three problems are described below.
# Progress in Transparent Nano-Ceramics and Their Potential Applications
## 4 Transparent Armor Nano-Ceramics
### Potential Application  
As depicted in Figure 14a, a large-scale MgAl\({}_{2}\)O\({}_{4}\) transparent nano-ceramic, 12 mm thick, was fabricated by gelcasting and pre-sintering in air HIP methods, and the average grain size was 8 \(\upmu\)m. In 1998, after realizing the mass production of powder, the research on AlON transparent ceramics progressed rapidly. At present, the largest size of AlON flat window that can be successfully fabricated is 880 \(\times\) 45 \(\times\) 12 mm [94]. In 2019, the Summet company realized the production and engineering application of large-scale AlON transparent nano-ceramics in batches through pressureless sintering and HIP methods [95]. Then, a high optical quality window, fabricated by AlON transparent nano-ceramics of about 0.41 m\({}^{2}\), was realized. The emergence of large-scale armored transparent ceramics makes these materials more frequently used in helicopter protection, personnel protection, infrared windows for reconnaissance, and other fields because their weight and thickness are only half of that of traditional bulletproof glass. Figure 14b shows the effect observed at a distance of 30 m from a \(\gamma\)-AlON transparent ceramic that was prepared by HIP post-treatment at 1800 \({}^{\circ}\)C for 2 h under 190 MPa [96].  
Unfortunately, at present, the manufacturing cost of transparent armor nano-ceramics is relatively high. A comparison of transparent armor materials for STANAG 4569 was conducted by [PERSON] et al. in 2017 [65] and is depicted in Figure 15. Compared with other materials, transparent nano-ceramic materials have the lowest areal density, only half of glass-ceramic materials. However, the maximum thickness of transparent armor nano-ceramics is still difficult to achieve compared to that of other materials. In addition, the manufacturing cost is also 5 to 10 times higher than other types of materials. To promote transparent armor nano-ceramics, therefore, it is necessary to reduce the fabricating cost.  
Figure 13: Samples and transmittance curve; (**a**) samples doped with different SiO\({}_{2}\) contents and different temperatures in the process of HIP; (**b**) transmittance of AlON transparent nano-ceramics doped with different SiO\({}_{2}\) contents at 1810 \({}^{\circ}\)C for 3 h [92]. Reprinted with permission from Ref. [92]. Copyright 2021, copyright ScienceDirect.  
This could be achieved by reducing manufacturing steps or finding other alternative materials. For manufacturing process optimization, one-step sintering methods need to be created in the future to obtain fully dense materials.
## Case Study
### Applying Stpafet
#### 5.2.3 Classification of Hazardous Events and Determination of ASIL  
FMEA now could be used for the classification of HE1 according to ISO26262. Steps will be performed as follows:  
* Fill CA1, CA2, UCA1, VH1, AC1 and possible operational situations into corresponding columns of FMEA in Table 5.
* Determine the ASIL for each hazardous event identified, taking HE1 as an example. As mentioned above, HE1 identified could be classified with two factors (S and E). The controllability for each hazardous event could be determined by the operational situations together with UCAs identified. The hazard events HE1 is a rear end collision on a highway with wet roads, which could cause fatal injuries, so the severity is determined as S3.
* Probability of exposure could be E3, medium probability. According to the operating modes and operational situation O1: driving on a highway with wet roads, and the unsafe control action UCA1: The FLEDS does not provide a warning signal when there is a low fuel level; the situation is difficult to control or uncontrollable, so the controllability is assigned as C3. Therefore, the ASIL of the hazardous event HE1 could be determined as ASIL C. The ASILs for VH1 under different operational situations are represented in Table 5.
* Formulate SGs according to each corresponding ASIL, still taking HE1 as an example. The SG for HE1 could be formulated according to SC-1 as SG.1: The vehicle must always provide correct information about the current fuel level in the tank to avoid unintended deceleration or stop when driving on a highway with wet roads.
## 5 Results and Discussion
### Comparison of Indirect Tensile Strength  
The indirect tensile tests were also conducted on the test specimens on a monthly interval with tests recorded on the 30 th, 60 th, and 120 th days of the exposure conditions. The comparison of indirect tensile properties along with the 28-day value is depicted in Table 7 and Figure 8 below:  
The marine conditioned specimens continued to develop higher tensile strength, as in the case of the pattern exhibited in the compressive strength tests. In contrast, ambient exposed samples reported minimal strength variations for the controls. However, contrary to the first-month compressive strength patterns, the tensile strength of the specimens after one month in marine conditions dropped by 11% compared to the 28-day values and similar samples in ambient exposure. However, after three months, the tensile strength reported a 9% increase, reaching 2.96 MPa. Hence, increasing tensile properties, like the compressive strengths, confirm the favourable heated environments under marine exposure. Unlike the conventional concrete, the self-compacting geopolymer concrete reports splitting tensile strength to be less than 10% of the compressive strength values, which is attributed to a greater fine content with high content of low calcium fly ash in the SGC [3,48].  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{Days of Exposure} & \multicolumn{2}{c}{Indirect tensile strength, MPa} & \multicolumn{2}{c}{Percentage change in weight between \(28\)-day value and ambient conditions} & \multicolumn{2}{c}{Percentage change in weight between \(28\)-day value and ambient and marine conditioned samples (\%)} & \multicolumn{2}{c}{Percentage change in weight between \(28\)-day value and ambient and marine conditioned samples (\%)} \\  & Value of 28-daycured specimen & Ambient conditions & Marine conditions & Ambient conditions & 28-day value and ambient conditions & 28-day value and ambient and marine conditioned samples (\%) & \multicolumn{2}{c}{Percentage change in weight between \(28\)-day value and ambient and marine conditioned samples (\%)} \\ \hline
30 & & 3.03 & 2.68 & \(1\) (\(+\)) & \(10.67\) (\(-\)) & \(11.55\) (\(-\)) \\ \hline
60 & 3 & 2.91 & 2.77 & \(3\) (\(-\)) & \(7.67\) (\(-\)) & \(4.81\) (\(-\)) \\ \hline
120 & & 2.98 & 2.96 & \(0.67\) (\(-\)) & \(1.33\) (\(-\)) & \(0.67\) (\(-\)) \\ \hline \hline \end{tabular} Note: (\(+\)) corresponds to an increase in value, (\(-\)) corresponds to a decrease in value.  
\end{table}
Table 7: Comparison of indirect tensile strength under ambient and marine exposure conditions.  
Figure 8: Indirect tensile strength of ambient and marine exposed specimens.
## 3 Numerical Simulations
### Parameter Identification with Different Integration Methods
#### 3.2.2 Damping Identification  
Although the performance of the three integration methods is satisfactory for the stiffness estimation, the damping of multi-DOF system is often difficult to be identified. Poor integration methods often make the identified damping results far away from the actual values. From Figure 5, it can be seen that the rectangular integration and the trapezoidal integration perform poorly even when the time step is set to be as small as 0.005 s. Relative damping errors with the rectangular integration and trapezoidal integration reach as high as 30% and 15.1%, respectively. Still, it should also be noted that the trapezoidal integration algorithm is better than the rectangular integration algorithm for estimating the damping. Obviously, the fourth-order Runge-Kutta integration estimates the damping perfectly, which almost converges to the actual damping value.  
Figure 4: Relative stiffness errors by three integration methods.  
Figure 3: Stiffness estimation by three integration methods: (**a**) rectangular integration; (**b**) trapezoidal integration; (**c**) fourth-order Runge–Kutta integration.  
The relative errors of the damping with the three integration methods were compared and are shown in Figure 6. It can be clearly found that the time step is very sensitive for the rectangular integration and the trapezoidal integration to identify the damping. Good results cannot be achieved until the time step reaches 0.001 s. However, the time step has little effect on the Runge-Kutta integration; good and stable results can be obtained although the time step is 0.025 s. By comparison, the fourth-order Runge-Kutta integration proves to be a good choice in such applications rather than the rectangular integration and the trapezoidal integration.
## 3 Results
### Effects of CJ on Hepatic ROS, LDH, and Renal Glucose, TC, ROS, and LDH Levels  
We evaluated the levels of hepatic ROS and LDH production altered in STZ-induced diabetic rats. In the Veh group, hepatic ROS and LDH levels were significantly increased compared with the Normal group (Figure 2). However, these elevations were observed to decrease with the administration of CJ. The ROS concentration in the CJ 100 group displayed normalization to levels similar to the Normal group. Hence, the administration of CJ is deemed beneficial for hepatic anti-oxidative activity based on these results.  
To confirm the renal functional variables affected by CJ, ELISA and ROS assays were conducted on kidney tissue. Renal glucose, triglyceride, ROS and LDH concentrations in the Veh group were increased compared to the Normal group (Figure 3). However, these elevated concentrations were significantly decreased in both the CJ and AG groups. Notably, the CJ groups exhibited a dose-dependent decrease.  
\begin{table}
\begin{tabular}{c c c c c c} \hline
**Group** & **Normal** & **Veh** & **CJ 50** & **CJ 100** & **AG 100** \\ \hline Glucose (mg/dL) & 115.6 \(\pm\) 3.7 *** & 443.2 \(\pm\) 6.9 & 393.9 \(\pm\) 13.2 ** & 302.4 \(\pm\) 28.4 *** & 344.7 \(\pm\) 71.4 * \\ ROS (fluorescences, min\({}^{-1}\)mL\({}^{-1}\)) & 8.1 \(\pm\) 1.7 *** & 37.9 \(\pm\) 2.0 & 25.5 \(\pm\) 2.0 ** & 6.6 \(\pm\) 0.7 *** & 16.5 \(\pm\) 4.2 *** \\ BUN (mg/dL) & 17.4 \(\pm\) 0.4 ** & 35.2 \(\pm\) 0.2 & 36.9 \(\pm\) 24.2 & 20.6 \(\pm\) 3.3 ** & 25.9 \(\pm\) 3.3 * \\ Creatinine (mg/dL) & 0.54 \(\pm\) 0.01 *** & 1.32 \(\pm\) 0.14 & 0.83 \(\pm\) 0.13 * & 0.58 \(\pm\) 0.02 *** & 0.62 \(\pm\) 0.05 *** \\ \hline \end{tabular} Values are expressed as the mean \(\pm\) SEM (\(n=8\)). * \(p\) \(<\) 0.05, ** \(p\) \(<\) 0.01, and *** \(p\) \(<\) 0.005 compared with the Veh groups. Normal, non-diabetic rats; Veh, STZ 30 mg/kg/tested rats; CJ 50, STZ 30 mg/kg + CJ 50 mg/kg-treated rats; CJ 100, STZ 30 mg/kg + CJ 100 mg/kg-treated rats; AG 100, STZ 30 mg/kg + aminoauridine 100 mg/kg-treated rats.  
\end{table}
Table 2: Effects of CJ on levels of glucose, ROS, BUN and creatinine in the serum of STZ-induced diabetic rats.  
Figure 2: Effects of CJ on hepatic (**A**) ROS production and (**B**) LDH production. Normal, non-diabetic rats; Veh, STZ 30 mg/kg-treated rats; CJ 50, STZ 30 mg/kg + CJ 50 mg/kg-treated rats; CJ 100, STZ 30 mg/kg + CJ 100 mg/kg-treated rats; AG 100, STZ 30 mg/kg + aminoauridine 100 mg/kg-treated rats. Values are expressed as the mean \(\pm\) SEM (\(n=8\)). ** \(p\) \(<\) 0.01, *** \(p\) \(<\) 0.001 compared with Normal. # \(p\) \(<\) 0.05, and *** \(p\) \(<\) 0.001 compared with Veh.
## 3 Experiment and Results  
In this section, we discuss the performance of the proposed stress recognition method using 3 DCGSA. In this study, experiments are performed in a subject-dependent manner, where the stress state model is trained for each subject and the stress state is classified. The accuracy for each subject is then calculated using 10-fold cross-validation, and the final classification accuracy for one stress dimension is the average of all subjects' classification accuracies. The 10-fold cross-validation evaluation means that 90% of the EEG data were randomly selected for training. The remaining 10% were used for testing, and this process was iterated ten times. Ten sets of results were finally averaged. The initial value of the learning rate was 0.0001, and it was dynamically adjusted according to the performance of the training set. This experiment performed 50 iterations with a batch size of 128. Furthermore, extensive experiments were conducted on three benchmark datasets to validate the superiority of the proposed 3 DCGSA.
# Flexible Rectenna on an Eco-Friendly Substrate for Application in Next-Generation IoT Devices
## 4 Conclusions  
In conclusion, we have proposed and experimentally demonstrated a compact, flexible, omnidirectional rectenna suitable for wireless energy harvesting and wireless power transfer of the next-generation ultra-low power IoT devices and wearable electronics, particularly those that require biodegradable and eco-friendly materials. The proposed rectenna can effectively receive signals from all directions over the broad frequency bandwidth, including 5G lower mid-band--2.3 GHz and 2.6 GHz--and ISM 2.4 GHz. Moreover, this article also presents the methodology for designing, optimizing, and fabricating the flexible rectenna for RF energy harvesting. The proposed flexible antenna presents several advantages over similar designs documented in the literature. Foremost among these is its capability to achieve a wide operating bandwidth while maintaining compact dimensions, ensuring coverage across multiple communication standards. A key performance highlight is the antenna's high radiation efficiency, exceeding 95% within the operating bandwidth. Furthermore, the design introduces a novel application of symmetric binary fractal tree geometry, effectively reducing the overall size and enhancing visual integration, resulting in a more esthetic and less obtrusive design.  
Conceptualization, N.A., B.A. and G.A.; methodology, N.A., B.A. and G.A.; software, N.A. and B.A.; validation, N.A., B.A. and G.A.; formal analysis, N.A. and G.A.; investigation, N.A., B.A. and G.A.; resources, N.A. and G.A.; data curation N.A., B.A. and G.A.; writing--original draft preparation, G.A.; writing--review and editing, N.A. and B.A.; visualization, B.A. and N.A.; supervision, G.A.; project administration, G.A.; funding acquisition, G.A. and N.A. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the BULGARIAN NATIONAL SCIENCE FUND at the Ministry of Education and Science, Bulgaria, grant number KP-06-H57/11 from 16 November 2021 \"Antenna structures for new energy sources in next-generation wireless networks\".  
Not applicable.  
The data presented in this study are available on request from the authors.  
The authors declare no conflicts of interest.  
The following abbreviations are used in this manuscript:  
IoTInternet of Things RFRadio Frequency