esa-sceva/satcom-chunk-collection huggingface dataset:
## 2 Theory
### From Homogeneous to Sandwich Partitions
 \tag{14}\]  
Equation (14) has six solutions: \(k_{x}=\pm\kappa_{1}\), \(\pm\mathrm{i}\kappa_{2}\) and \(\pm\mathrm{i}\kappa_{3}\). Figure 4 shows an example of wavenumbers (absolute values) obtained from Equation (14). Figure 3: Sandwich beam: schematic (**a**) and displacement (**b**). \(\kappa_{1}\) is the wavenumber associated with the first propagating wave. This number is bounded by two limits: a lower asymptote describing the flexural wave in a slender Euler beam and an upper asymptote describing the flexural wave in a laminate:  
\[\lim_{f\to 0}|\kappa_{1}| =\left(\frac{m^{\prime}\omega^{2}}{D_{1}^{\prime}}\right)^{1/4}; \lim_{f\rightarrow\infty}|\kappa_{1}| =\left(\frac{m^{\prime}\omega^{2}}{2D_{2}^{\prime}}\right)^{1/4}. \tag{15}\]  
Therefore, the model proposes to consider the structure as an 'equivalent' homogeneous beam having the same dynamic properties as the sandwich beam at hand. If a frequency-dependent 'apparent' bending stiffness, \(D_{a}^{\prime}\), is defined, one can write:  
\[\kappa_{1}^{4}=\frac{m^{\prime}\omega^{2}}{D_{a}^{\prime}}. \tag{16}\]  
A discussion of the possible ways to model the apparent bending stiffness and their implications can be found in [27]. Inserting Equation (16) into Equation (14), an equation in \(D_{a}^{\prime}\) is obtained. In the case of honeycomb beams, laminates are generally less stiff than the entire beam, and \(D_{1}^{\prime}\gg D_{2}^{\prime}\) simplification can be done. If \(\omega^{2}l_{\omega}^{\prime}\ll G_{c}S\), the motion equation can be further simplified as:  
\[\left(\frac{G_{c}S}{\sqrt{m^{\prime}}\omega}\right)\left[\frac{{D_{a}^{\prime }}^{3/2}}{D_{1}^{\prime}}-{D_{a}^{\prime}}^{1/2}\right]+D_{a}^{\prime}-2D_{2} ^{\prime}=0, \tag{17}\]  
which can be written in the general form:  
\[\frac{A}{f}{D_{a}^{\prime}}^{3/2}-\frac{B}{f}{D_{a}^{\prime}}^{1/2}+D_{a}^{ \prime}-C=0 \tag{18}\]  
once coefficients \(A\), \(B\) and \(C\) are defined:  
\[A=\frac{G_{c}S}{\sqrt{m^{\prime}}2\pi D_{1}^{\prime}}; B=\frac{G_{c}S}{\sqrt{m^{\prime}}2\pi}; C=2D_{2}^{\prime}. \tag{19}\]  
Figure 4: Example of wavenumbers obtained from Equation (14) (beam data source: [27], except laminate thickness, assumed 1 mm for both leaves). It has been shown that solutions based on this formulation are accurate enough to describe the behavior of a sandwich structure in several practical applications [15; 26].
## 2 Electrical Resistivity/Impedance Measurement: Is It Really that Simple?
### Defects and Damages Detection
[39] found that reduction in water content significantly decreases the piezoresistive property, both in terms of FCR and sensitivity to stress and strain; this can be attributed to the decrease of contact between eventual fillers (they tested both carbon nanotube and nanocarbon black) and the shrinkage increase [223]. It is worth noting that the water content generally increases with conductive fillers content because of their water absorption capability. The importance of moisture content is highlighted also in other studies. [PERSON] et al. [50] studied the evolution of electrical resistivity with cracking in concrete specimens saturated with a basic solution, noticing a decrease of electrical resistivity when crack opens, since the ionic solution takes up and fills it. [PERSON] et al. [123] maintained specimens in saturated water condition before tests, to exclude moisture effect on impedance measurement; after damage, the specimens were subjected to wet/dry cycles to enable self-healing. They noticed that both opening and number of cracks influence the measurement results; the relation between electrical impedance and crack opening is frequency-dependent and presents both a resistor and a capacitor effect: the former is linked to the conductive media inside the crack, whereas the latter linearly decreases with increasing crack opening. [PERSON] et al. [91] considered both plain mortar and ECCs; they highlighted that in fractured mortars the electrical impedance increases several hundred times, resulting in different shape and trend curves representation in Nyquist plot.
# Machine Learning-Assisted Secure Random Communication System
## 6 Results and Discussion
### Intended Communication
#### 6.1.1 Confusion Matrices  
We compute the confusion matrices for the 'transmitted bits' against the'retrieved bits' in Figure 8. The established trend of exhaustively varying one of the SkaSNSK responsible factors (\(\alpha\), \(\Delta\beta\), and \(N\)) and keeping the others fixed was also adopted while analyzing the ML-RCS with confusion metrics. The MSNR was constant throughout the confusion matrix.  
Firstly, as shown in Figure 8 (left column), \(\Delta\beta\) varies from 1.6 to 2. Similar to the demo transmission, the expected increase in performance is also observed in the confusion matrix as \(\Delta\beta\) increases, as shown in Figure 8 (left column). Second, as shown in Figure 8 (middle column), \(\alpha\) is changed from 0.6 to 1.1 while keeping \(\Delta\beta\) and \(N\) fixed. Given the results of the demo transmission, we observed a similar increase in the performance of the confusion matrices for \(\alpha\). Finally, similar effects were also observed when varying \(N\) while keeping \(\alpha\) and \(\Delta\beta\) constant; this is also shown in Figure 8 (right column). The performance appeared to increase with every increment in \(N\) from 15 to 35.  
Compared with the successful results obtained during the demo transmissions for a few transmitted bits, the previous results show that the ML-RCS achieves a favorable performance for many bits. The confusion matrices derived for all the SkaSNSK responsible factors (\(\alpha\), \(\Delta\beta\), and \(N\)) also reflect similar trends in the performance of the ML-RCS with increasing values of \(\alpha\), \(\Delta\beta\), and \(N\), resulting in fewer errors between the transmitted and retrieved bits.
# Multi-Satellite Task Parallelism via Priority-Aware Decomposition and Dynamic Resource Mapping
###### Abstract  
Multi-satellite collaborative computing has achieved task decomposition and collaborative execution through inter-satellite links (ISLs), which has significantly improved the efficiency of task execution and system responsiveness. However, existing methods focus on single-task execution and lack multi-task parallel processing capability. Most methods ignore task priorities and dependencies, leading to excessive waiting times and poor scheduling results. To address these problems, this paper proposes a task decomposition and resource mapping method based on task priorities and resource constraints. First, we introduce a graph theoretic model to represent the task dependency and priority relationships explicitly, combined with a novel algorithm for task decomposition. Meanwhile, we construct a resource allocation model based on game theory and combine it with deep reinforcement learning to achieve resource mapping in a dynamic environment. Finally, we adopt the theory of temporal logic to formalize the execution order and time constraints of tasks and solve the dynamic scheduling problem through mixed-integer nonlinear programming to ensure the optimality and real-time updating of the scheduling scheme. The experimental results demonstrate that the proposed method improves resource utilization by up to about 24% and reduces overall execution time by up to about 42.6% in large-scale scenarios.  
task decomposition; satellite network; resource mapping; reinforcement learning; task dependency Article
# Research on a Piezoelectric Pump with Flexible Valves
## 5 Conclusions  
In this paper, in order to integrate the valved PZT pump and the valveless PZT pump, a flexible valve was proposed and applied to a PZT pump. The main conclusions are drawn as follows:  
* The working principle of the PPFV was introduced, a simplified model of the flexible valve was established, and its response to the loads was analyzed. It is known that the pressure change in the pump chamber caused by the vibration of the PZT vibrator is beneficial to the realization of the valve transport function. It was proved theoretically that this kind of pump can realize the conversion between a valved state and a valveless state by controlling the input signal of the PZT vibrator.
* The prototype of the PZT pump with flexible valves was manufactured, and its output performance was obtained through experimental research. The flow rate of the pump increased with the increase in voltage, but the flow rate-frequency relationships were not linear. The frequency corresponding to the maximum flow rate was not sensitive to the voltage change. The maximum flow rate measured under the voltage of 100 V was 119.61 mL/min (25 Hz), and the maximum output pressure was 6.16 kPa (25 Hz).
* We observed the working-state of one flexible valve in different input voltages, 100, 80, and 40 V at 25 Hz. It showed that the valved pump and the valveless pump existed in one, which proved that the valved state and the valveless state of the pump can be switched by adjusting the voltage. When the voltage was 100 V, it was a valveless PZT pump with a large flow rate and high output pressure. However, it was a valveless PZT pump with a small flow rate and low pressure difference when the voltage was lower than 80 V.  
This paper represents a result of collaborative teamwork. [PERSON] and [PERSON] conceived and designed the experiments; [PERSON] performed the experiments and wrote the manuscript; [PERSON] and [PERSON] analyzed the data; [PERSON] provided constructive suggestions; [PERSON] and [PERSON] revised the manuscript. All authors have read and agreed to the published version of the manuscript.  
This research was funded by \"Graduate AbilityPromotion Plan of Guangzhou University, Guangzhou, China, grant number 2019 GDJC-M20\", \"Guangdong Basic and Applied Basic Research Foundation, Guangdong, China, grant number 2019B1515120017\" and \"National Natural Science Foundation of China (NSFC), China, grant number 51705093\".  
Not applicable.  
The authors declare no conflict of interest.
## 2 The LeGNSS Constellation  
The constellation configuration of the LeGNSS is presented as follows: GPS satellites are operating in six orbital planes with a 55\({}^{\circ}\) inclination angle at 20,200 km in altitude, while BDS has three types of satellites. The GEO satellites, with a period of revolution of 23 h 56 min at 35,786 km in altitude, are positioned along the equator at 58.75\({}^{\circ}\)E, 80\({}^{\circ}\)E, 110.5\({}^{\circ}\)E, 140\({}^{\circ}\)E, and 160\({}^{\circ}\)E, respectively. The IGSO satellites have an inclination of 55\({}^{\circ}\), and their orbital periods are the same as those of GEO satellites. The MEO satellites are distributed in three orbital planes with an inclination of 55\({}^{\circ}\) at 21,528 km in altitude. The orbital period of MEO satellites is 12 h 53 min. The Iridium constellation has six orbital planes spaced 30\({}^{\circ}\) apart with 11 satellites in each plane. The orbital plane is inclined at 86.4\({}^{\circ}\) and approximately 780 km in altitude. Iridium has the most latitude coverage due to the near-polar circular orbits. Figure 1 shows the whole constellation of LeGNSS, which clearly displays the different altitudes of all types of satellite.  
Although the major part of the LeGNSS is similar to the current GNSS, the important component of the LeGNSS is the LEO constellation that can transmit GNSS-like signals to the ground receivers. The whole system will be operated as follows: All satellites in LeGNSS will transmit navigation signals, onboard LEO receivers receive signals from GNSS satellites in view, while ground receivers receive signals from all satellites. Data at ground stations will be streamed to a computation center in real-time for generating precise orbit and clock products. Onboard LEO data can also be streamed to the computation center for centralized processing or processed directly onboard with precise orbit and clock products of GNSS satellites held fixed. With these LeGNSS products, precise point positioning can be conducted.
# Full Digital Workflow for Aesthetic Rehabilitation of the Upper Tenth: A Case Report
## 2 Materials and Methods
### Cementation of Veneers  
Isolation was achieved by means of a rubber dam (Nic Tone Dental Dam, thick, mint, MDC dental, Zapopan, Mexico). Next, teeth were air-abraded using 20 um aluminum oxide particles with AquaCare Aluminium Oxide Air Abrasion Powder (Velopez, London, UK). Air-abrading the prepared teeth before cementation ensures thorough cleaning of debris and contaminants while creating a micro-retentive surface for improved bond strength between the tooth and the restorative materials. This process optimizes the longevity and effectiveness of dental restorations by minimizing microleakage and promoting durable adhesion. After meticulous cleaning and drying, interproximal surfaces were secured using Teflon tape (PTFE Iso Tape 5 mm Santa Catarina, Brasil).  
Next, teeth were etched using 35% phosphoric acid (Scotchbond Universal Etchant, 3M ESPE, St. Paul, MN, USA) for 20 s and abundantly washed with distilled water and dried. Afterward, Scotchbond Universal Plus adhesive (3M ESPE, St. Paul, MN, USA) was applied according to the manufacturer's instructions: dried with air directly to eliminate the solvents from the adhesive and left unpolymerized until the veneers were placed (following recommendations in the RelyX Universal instructions).  
The intaglio surfaces of ceramic restorations were etched with 10% hydrofluoric acid (porcelain etch, Ultradent Product Inc., South Jordan, UT, USA) for 20 s and cleaned in an ultrasonic tube. Next, intaglio surfaces were uniformly covered with Ceramic Silane (3M ESPE, St. Paul, MN, USA). After drying the silane, cement was applied after 10 s.  
Translucent light-cure resin cement (RelyX Universal, 3M ESPE, St. Paul, MN, USA) was introduced on the inner part of the veneers following the manufacturer's instructions. Next, veneers, one by one, were positioned on the prepared teeth. Firstly, central incisors were cemented simultaneously. Next, other veneers were introduced and polymerized separately. The excess cement near the margins was eliminated using an ECCSO LM Arte instrument (LM-Dental, Parainen, Finland). Polymerization was performed for 20 s/surface with a light-emitting diode (LED) light-curing unit curing pen (Eighteeth, Changzhou, China) at 1000 mW/cm\({}^{2}\). Each surface, including the facial, palatal, mesial, and distal, was polymerized.
# Monitoring the Dynamics of Ephemeral Rivers from Space: An Example of the Kuiseb River in Namibia
## 2 Ephemeral Rivers  
### General Information  
Ephemeral and intermittent rivers, characterized by occasional, periodic, or recurrent water flows, represent about half of all rivers on Earth and are located in different climates: temperate, boreal, humid tropical, and arid [10; 11; 12]. Here, we only focus on ephemeral rivers, which are defined by having measurable flow in the riverbed for less than 10% of the year and with flood peaks that last from a few hours to a few days [3; 8]. In recent years, the number of ephemeral rivers has increased worldwide as a consequence of the combined effects of climate change and land use changes, which have reduced discharge in historically more constant flowing rivers [11; 13]. Reduced flows do not only have a significant effect on human populations and their livelihoods along river courses, but also have significant repercussions on biodiversity and associated ecosystems.  
Ephemeral rivers first interested scientists in the fields of biodiversity and ecology, since they consist of a multitude of habitats (terrestrial, lotic, lenti) with a rich biodiversity of resilient species that are resistant to the extreme fluctuations between aquatic and terrestrial conditions [11; 14]. Although there is a continued interest in the ecological understanding of ephemeral rivers, studies on hydrological aspects remain limited. Even though hydrologists started to pay more attention to ephemeral rivers and their flood intervals due to the importance of these rivers as the main source of water to humans and biodiversity in arid and semi-arid zones, they are hampered by data limitations [3]. Water arrives quickly in the main bed of the river during periods of flooding, and then infiltrates into the substrate at variable speeds, which drives the development of vegetation and recharge of aquifers [3; 10]. It is this dynamic between sudden floods, subsequent infiltration, and the response of vegetation and rising groundwater levels that is of interest to hydrologists.  
The limited number of studies on the hydrological processes of ephemeral rivers are mainly due to inadequate and inappropriate tools for monitoring the brief and highly dynamic hydrological phenomena of these systems [12]. Indeed, most in situ gauging stations have been developed for and are located on permanent rivers, being very rare in arid and semi-arid areas. They are even more rarely combined with geohydrorological gauges to monitor infiltration rates and fluctuations in groundwater levels. Fortunately, for about two decades, the increased sophistication and availability of remote sensing data have offered new tools for the study of hydrological phenomena in ephemeral rivers.
## 2 Optimal Design of the TID
### Optimization Results
To evaluate the impact of the mass ratio on the optimal parameters of the TID, the mass ratio was taken from 0.05 to 1.0 at intervals of 0.05, and the period and damping ratio  
Figure 5: The relationship of the optimal parameters of the TID and the dynamic characteristics (damping ratio and natural vibration period) of the based-isolated structure (\(\mu=0.2\)). of the based-isolated structure are combined in two groups, namely \(T_{b}=1\ s\), \(\xi_{b}=0.15\) and \(T_{b}=6\ s\), \(\xi_{b}=0.15\), respectively. Figure 6 shows the optimal frequency ratio and damping ratio of the TID with different mass ratio, for the far-fault, no pulse near-fault and pulse near-fault ground motions, and shows the optimal parameters under white-noise excitation as shown in Equation (14) for comparison at the same time. It can be seen that the variation trend of the optimal parameters with the mass ratio under these three types of ground motion is similar to that under the white-noise excitation. However, the larger the mass ratio is, the larger difference between the optimal parameters under different excitations is. When the base-isolated structure has a period of \(6\ s\), the optimal parameters under the no pulse near-fault ground motion are notably higher than those observed under both far-fault and near-fault pulse ground motion, while the optimal parameters of the latter two conditions are very close. This is due to the strong correlation between the optimal parameter values and the ratio of the frequency of the base-isolated structure to the filter parameters of the power spectrum model. It can be observed that the filter parameters of far-fault ground motion are equal to those of near-fault pulse ground motion, but significantly distinct from those of near-fault non pulse ground motion. This has led to the phenomenon of differences in the optimal parameters mentioned above. Figure 6: The connection of the optimal parameters of the TID and the mass ratio for \(T_{b}=1\ s\), \(\xi_{b}=0.15\) and \(T_{b}=6\ s\), \(\xi_{b}=0.15\). In summary, the optimal parameters are affected by many factors, such as the natural vibration period and damping ratio of the base-isolated structure, the mass ratio of the TID, and the type of excitation load. Therefore, the optimal parameters for identifying TID must comprehensively consider the impact of the detailed dynamic characteristics of the base-isolated structure.
# Acquisition and Processing of UAV Fault Data Based on Time Line Modeling Method
## 2 Related Work
### Related Fault Detection or Intrusion Detection Models
#### 2.1.2 Deep Learning-Based Models  
In 2021, [PERSON] et al. [9] used the bidirectional long short-term memory neural network (BiLSTM) to match the attack according to the existing attack of the model: if the match is successful, a warning is issued; if no attack is matched, the data is sent to an anomaly detector based on the Local Outlier Factor (LOF). If the anomaly detector detects an anomaly, it will issue an alarm and collect the data of this attack instance, then mix the new instance data with the old data and send them to the BiLSTM for training to complete incremental learning. The authors used the CSE-CIC-IDS2018 data set [10] to test the model. In 2022, [PERSON] et al. [11] used a deep convolutional neural network to detect malicious threats from drones in Wi-Fi traffic. Two-way and one-way drone traffic data were used for model training and testing. In 2022, [PERSON] et al. [12] proposed to use variants of the Long Short-Term Memory neural network (LSTM) to detect anomalies and faults simultaneously. This model consists of the main branch and two sub-branches. The main branch produces the general LSTM encoder architecture. The two sub-branches are used to detect anomalies and faults.
# A Cache Policy Based on Request Association Analysis for Reliable NAND-Based Storage Systems
## 6 Conclusions  
In the paper, we propose a cache policy based on request association analysis for reliable NAND-based storage systems. The proposed method contains two components: a request association analyzer and request association cache. The request association analyzer is to find out strong requests by performing request association analysis, and then the request association cache can dynamically separate strong and weak request data according to the selected strong requests. Furthermore, the request association cache can keep the strong request data in the cache as much as possible to improve the cache hit ratio. After the cache hit ratio is increased, we can reduce a lot of pages written to NAND flash memory and also reduce the activities of garbage collection. As the activities of garbage collection contain a large amount of valid pages written and time-consuming erase operations to reclaim free space, the proposed method can keep the strong request data in the cache to improve the performance of NAND flash memory. In addition, to reduce the overhead of the request association analyzer, we also propose delaying the execution of the request association analyzer as much as possible without reducing the cache hit ratio too much. When compared with the typical cache methods (such as LRU, ARC and VBBMS), the proposed method can improve the average cache hit ratio by about 35.08%, 18.44% and 26.04%, respectively. Additionally, the proposed method with execution delay of the request association analyzer can also improve the average cache hit ratio by about 29.86%, 14.09% and 21.3%, respectively, when compared with LRU, ARC and VBBMS. Furthermore, the proposed method with execution delay of the request association analyzer can extend the computation interval by about 2 times to 34 times so that the computation overhead caused by the association analysis can be reduced. We can also show that the average computation time of the association analysis is reasonable and short (e.g., about 0.3 s) when compared to the computation interval so that the proposed method based on request association analysis is practical and efficient.  
For future work, we will investigate how to reduce the overhead of the request association analyzer and also improve the hit ratio of the request association cache. Therefore, we should find a better method to extend the computation interval of the association analysis without reducing the cache hit ratio too much.  
Conceptualization, C.-H.S. and C.-H.W.; methodology, C.-H.S. and C.-H.W.; formal analysis, C.-H.S. and C.-H.W.; writing--original draft preparation, C.-H.S. and C.-H.W.; writing--review and editing, C.-H.S. and C.-H.W. All authors have read and agreed to the published version of the manuscript. This work is supported in part by a research grant from the Ministry of Science and Technology under Grant MOST 108-2221-E-011-057-MY3. The authors declare no conflict of interest.