esa-sceva/satcom-chunk-collection huggingface dataset:
# Fault Tolerant DHT-Based Routing in MANET
## 6 Conclusions  
In this paper, we outline the challenges to address the problem of fault tolerance in DHT networks and provide a suite of distributed mechanisms to solve the identified issues. We have described that network dynamics (i.e., node(s)/link(s) failure, network partition, merging, etc.) halt communication in the DHT network and limit the scope of such protocols in the adversarial environment offered by MANET.  
In particular, a fault-tolerant DHT-based (FTDN) routing protocol is proposed for MANET. FTDN builds and maintains a logical tree-structured network over MANET's ad hoc physical topology and eliminates flooding at the control and data plans. FTDN, using a cross-layer design approach, exploits \(k\)-hop topological information (i.e., physical network connectivity/dis-connectivity) along with the philosophies of detection, recovery, avoidance, and redundancy. Moreover, FTDN considers pre-failure measures (i.e., measuring network dynamics, replication, and partition detection) and post-failure measures (i.e., finding alternate paths avoiding the failure, merging detection, merging, i.e., reconfiguration). These measures ensure DHT-network availability and make the system reliable, fault-tolerant in adversarial environments. Performance evaluation confirms the effectiveness of the solutions provided.  
In the future, we would like to extend the performance analysis in two directions: (1) current implementation considers 1-hop topological information; in the future, we would like to use a different variation of \(k\). (2) To implement the proposed solutions in other logical structures by considering different performance parameters (throughput, etc.).  
**Author Contributions:** Conceptualization, S.Z.; formal analysis, S.Z. and K.U.; funding acquisition, M.Z. and R.R.B.; investigation, S.B. and M.Z.; methodology, S.Z. and K.U.; project administration, A.W.; resources, R.R.B.; software, A.W. and S.B.; writing--original draft, S.Z.; writing--review and editing, A.W. All authors will be informed about each step of manuscript processing including submission, revision, revision reminder, etc., via emails from our system or assigned Assistant Editor. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research was funded by Tecnologico de Monterrey, Escuela de Ingenieria y Ciencias, Av. General Ramon Corona 2514, Zapopan, Jalisco 45201, Mexico.  
**Conflicts of Interest:** The authors declare no conflict of interest.  
Figure 10: Normalized overhead results, as boxplots, against different node moving speeds with varying network sizes.
## 2 The Classical Exact Methods
### [PERSON]'s Method  
[PERSON]'s method [19] has the great advantage that only the eigenvector of interest is required. Its basic idea is to convert the eigenvector sensitivity into the sum of the general solution and the special solution of Equation (3). Then the general solution and the special solution are solved, respectively. The specific operation steps are as follows:  
Letting  
\[\eta_{j}=(\frac{\partial\lambda_{j}}{\partial p_{i}}M+\lambda_{j}\frac{ \partial M}{\partial p_{i}}-\frac{\partial K}{\partial p_{i}})\phi_{j} \tag{9}\]  
\[\Omega=K-\lambda_{j}M \tag{10}\]  
Then Equation (3) simplifies to:  
\[\Omega\frac{\partial\phi_{j}}{\partial p_{i}}=\eta_{j} \tag{11}\]  
Since the matrix \(\Omega\) in Equation (11) is a singular matrix, it is impossible to directly calculate \(\frac{\partial\phi_{j}}{\partial p_{i}}\) by using the matrix inverse technique. From Equation (11), \(\frac{\partial\phi_{j}}{\partial p_{i}}\) can be expressed as the sum of the general solution and a special solution of Equation (11). According to Equation (1), the general solution (singular solution) of Equation (11) is \(\phi_{j}\). Assuming a special solution of Equation (11) is \(\zeta_{j}\), one has  
\[\frac{\partial\phi_{j}}{\partial p_{i}}=\zeta_{j}+\delta\phi_{j} \tag{12}\]  
The next task is to solve the special solution \(\zeta_{j}\) and the coefficient \(\delta\). In order to find the special solution, Equation (11) can be constrained and rewritten as  
\[\overline{\Omega}\frac{\partial\phi_{j}}{\partial p_{i}}=\overline{\eta_{j}} \tag{13}\]where \(\overline{\Omega}\) is a nonsingular matrix obtained by replacing the elements in \(\Omega\) of the \(x\) row and the \(x\) column with 0, and replacing the \((x,x)\) element with 1. Here the \(x\) represents the row number of the largest element in \(\phi_{j}\). \(\overline{\eta_{j}}\) is obtained by replacing the element in the \(x\) row of \(\eta_{j}\) with 0. From Equation (13), the special solution \(\zeta_{j}\) can be obtained as  
\[\zeta_{j}=\overline{\Omega}^{-1}\overline{\eta_{j}} \tag{14}\]  
by taking partial derivative of Equation (2) with respect to \(p_{i}\), one has  
\[\phi_{j}^{T}M\frac{\partial\phi_{j}}{\partial p_{i}}=-\frac{1}{2}\phi_{j}^{T} \frac{\partial M}{\partial p_{i}}\phi_{j} \tag{15}\]  
substituting Equation (12) into Equation (15), the coefficient \(\delta\) can obtained as  
\[\delta=-\frac{1}{2}\phi_{j}^{T}\frac{\partial M}{\partial p_{i}}\phi_{j}-\phi_ {j}^{T}M\zeta_{j} \tag{16}\]  
It can be seen from the above processes that [PERSON]'s method needs several operation steps. There is no unified formula for calculating the sensitivities of different eigenvectors, since the positions of the largest elements in different eigenvectors are always changing in the process of finding specific solutions.
# A 3D Two-Phase Landslide Dynamical Model on GIS Platform
## 5 Discussion
The three-dimensional model treats the friction between the earth's mass flows as fluid friction. The interFoam solver in OpenFOAM is built upon this foundation. However, the actual process of landslide motion is more complex. Different stages and regions of landslide motion exhibit varying levels of friction. For instance, the initial stage involves larger block movements, while the deposition phase features smaller blocks. The upper part of the landslide body contains larger blocks compared to the smaller blocks in the lower part. Size effects are present among the landslide blocks [50], where larger particles exhibit rigid-body motion, and smaller particles behave more like fluid motion [51]. Frictional behavior typically involves Coulomb friction for the flow of large solid particles, such as large blocks. In contrast, the flow of smaller particles often exhibits fluid friction. Accurately describing the process of transitioning from Coulomb friction to fluid friction and specifying the friction types in different parts of a landslide is a challenging task. Our model, which treats the friction between landslide blocks as fluid friction, has limitations that result in discrepancies with the results of two-dimensional models. To address this issue, future work will involve the development of new solvers. Future research can involve coupling Coulomb friction with fluid friction during the landslide motion process. Coulomb friction may be applied to larger blocks, while fluid friction can be utilized for smaller particles. The key technological challenges lie in understanding the transition between the two friction types and determining appropriate boundary conditions.
## 2 Materials and Methods
### EO Image Processing
#### 2.8.1 Sentinel-2 Parser  
The sentinel-2 parser has been implemented for the retrieval of EO images. This parser receives input coordinates showing the location of the event selected by the user and a timestamp. A before and an after depiction of the location provided are retrieved from the Copernicus Open Access Hub in order to be processed through the sub-modules included in the image processing module.  
This sub-module is not only responsible for the retrieval of the sentinel-2 images but also for their conversion to RGB images in order to be used as input in the building footprint extraction and damage detection sub-module. It should be mentioned that the sentinel-2 data that will be retrieved will include 13 spectral bands: four bands at 10 m, six bands at 20 m, and three bands at 60 m spatial resolution.
# Marine Internet for Internetworking in Oceans: A Tutorial
## 5 Internetworking Strategies of Marine Internet
### Integrated Coastline Network (ICN)
#### 5.1.1 Exploiting of Mobile Cellular Spectra  
As mentioned above, the maritime radio system is short of bandwidth to satisfy their ever-increasing communication demands, while mobile systems have many expensive spectra, as listed in Table 7. However, thus far, most of these bandwidths mainly cover terrestrial environments. To enhance maritime radio systems and improve utilization of these spectra, it is inspiring to exploit these spectra and the corresponding technologies to provide cost-effective marine Internet services.  
After more than three decades of development, mobile systems have become the most successful enabling technologies for mobile Internet access available anytime and anywhere. Thus, expending these services to near water areas in oceans can satisfy many marine Internet users. The communication services provided by maritime radio systems have to be reliable, timely and accurate, especially for  
Figure 5: A large-scale cooperative networking structure for marine Internet with the following communication links: terminal to terminal (T-T), BS to terminal (B-T), BS to BS (B-B), satellite to BS (S-B), BS to BS/terminal (B-B,T), terminal/BS to BS/terminal (T,B-B,T) and hydrophone to hydrophone (H-H).  
real-time navigation, distress beacon transmission and rescue as well as safety operations. These services have been successfully provided by the current maritime radio system. The enhanced maritime services should be privileged in using the shared spectrum of mobile cellular systems.
# Dynamic Measuring Method of Laser Beam Incident Angle for Laser Doppler Vibrometer
## 4 Dynamic Measuring Method of Incident Angle  
In Section 3, the true value of the incident angle of the LDV laser beam in the current installation state is obtained utilizing static measurement. However, this method is not suitable for space-constrained situations. Therefore, this section will propose a dynamic measuring method to measure the incident angle of the same LDV again. By comparing the measurement results of the two methods, it is demonstrated that the new method can replace the traditional measuring method.
###### Abstract  
Granite residual soil is one of the most frequently encountered problem soils in tropical regions, whose mechanical behavior heavily depends on the pattern of variation of mean effective stress (\(p\)') during shearing, which can be classified into three categories: increasing-\(p\)', constant-\(p\)', and decreasing-\(p\)'. Unfortunately, so far, the stress-strain strength characteristics of granite residual soils have been studied mainly under increasing-\(p\)' stress paths, although it is very likely to encounter stress paths with decreasing \(p\)' in practice, especially in excavation engineering. Moreover, most pertinent research has focused on remolded granite residual soils, whereas undisturbed specimens have not yet received enough attention. In this paper, stress path triaxial tests considering different patterns of variation of mean effective stress were conducted on an undisturbed granite residual soil. Subsequently, a variable termed loading angle was introduced to quantitatively represent stress path. The influences of stress path on the Mohr-Coulomb strength parameters, deformation characteristics, ductility, and shearing stiffness were analyzed, with an emphasis on the role of pattern of variation of mean effective stress. The experimental results show that friction angle of the soil increases while cohesion decreases with the increase in loading angle. The increase in loading angle leads to less volume contraction and smaller failure strain. During shearing, the soil exhibited a less brittle response under stress paths with smaller loading angles. The initial secant shear modulus first decreased and then increased as the loading angle increased, with the minimum shearing stiffness occurring at a certain loading angle lying between 90 deg and 123.7 deg.  
undisturbed granite residual soil; stress-strain strength; ductility; stiffness; stress path; mean effective stress +
Footnote †: journal: Applied Sciences
## 4 Discussion
Different imaging techniques may catch different aspects of bone properties when they are also performed at the same skeletal site. For example, DXA of the lumbar spine provides only 2D quantitativemeasurements of bone, without offering any qualitative 3D information about trabecular bone structure [21]. At the same time, TBS from lumbar spine DXA is able to provide only an \"indirect\" measurement of bone trabecular microstructure [9]. Lumbar QCT, on the contrary, provides specific 3D data of lumbar vertebrae, allowing a direct assessment of trabecular bone. This could partly explain why this parameter is able to better distinguish between women who have vertebral fractures and those who do not [12; 13]. Evaluation of diagnostic performance in the prediction of fragility fractures showed that the AUC values of aBMD were not only lower than vBMD, but also than TBS. This may be partly attributable to the fact it has been reported that TBS values are less affected by spondylarthosis compared to aBMD [15]. In fact, a study by [PERSON] et al. conducted on 1254 postmenopausal women showed that lumbar osteoarthritis led to an increase in lumbar spine BMD, while TBS was not affected by lumbar osteoarthritis, with no significant difference in TBS values between patients with and without lumbar osteoarthritis [15; 24]. The systematic bias resulting from the Bland-Altman analysis between DXA aBMD and DXA TBS is in line with this, confirming that BMD values consistently higher than TBS may be attributable to osteoarthritis. The relatively wide limits of agreement between aBMD and TBS suggest that while these two indices are related, the considerable variability between these two parameters confirms the evidence that TBS provides complementary information to BMD, particularly in assessing bone quality beyond density alone [9; 25; 26]. Our study has some limitations, the main being the retrospective design and the small number of participants. Another limitation is the absence of an ad hoc analysis of subgroups of patients according to age, gender, and vertebral fractures, as well as between patients with and without spondylarthosis, which could provide more granular insights into the variability of the measurements. Future studies with larger sample sizes should explore these stratifications to better understand their potential impact on the observed findings.
# Towards a Heat-Resistant Tethered Micro-Aerial Vehicle for Structure Fire Sensing
## 5 Manufacturing and Assembly  
As previously stated, the ducts are 3D printed in a high-temperature polycarbonate using a conventional 3D printer. After that, they are covered with carbon fiber felt cut to size and glued with a high-temperature spray adhesive. Finally, the carbon felt is covered with a heat-shield reflective golden tape.  
The carbon fiber panels are layered following the scheme proposed in Figure 3. High-temperature spray adhesive is applied between each layer, forming a robust sandwich panel. All the internal electronics are placed over aluminum spacers to isolate them from direct-contact thermal conduction. All the components are soldered and screwed into place. The ducts are inserted into position, and the inner volume is closed with the top panel of the frame.  
Lastly, the lateral felt is cut to size and fixed around the lateral of the quadcopter with hook-and-loop tape to conform an enclosed volume. The tether is protected by a fire-resistant fiberglass braided sleeve. An example of the manufactured UAV can be found in Figure 9.  
Figure 8: Measured temperature in test sample versus simulated temperature.
# Modified Equation of Shear Strength with Respect to Saturation
## 2 Theory
### The New Model  
Equations (2) and (4) can be put into Equation (1) to obtain the final shear strength model, which includes the degree of saturation, the net normal stress, the effective cohesion, and the internal friction angle. Equation (5) shows the expression of the shear strength model of multiple parameters:  
\[\tau_{f}=c^{\prime}+\left\{(\sigma-u_{a})+\frac{\xi_{4}}{1+\xi_{2}e^{\xi_{3}S_{ r}}}\cdot\left[\left(\frac{S_{r}-S_{rw}}{1-S_{rw}}\right)^{-1/m}-1\right]^{1-m} \right\}tan\phi^{\prime} \tag{5}\]  
where \(\xi_{2}\), \(\xi_{3}\), and \(\xi_{4}\) are the fitting parameters, \(\xi_{4}\) is a parameter that is related to air entry value \(\left(\xi_{4}=\xi_{1}\cdot P_{0}\right)\); \(m\) is a parameter that is related to the material characteristics; \(S_{r}\) is the degree of saturation; \(S_{rw}\) is the residual degree of saturation; \(c^{\prime}\) is the effective cohesion; \(\phi^{\prime}\) is the effective internal friction angle; \((\sigma-u_{a})\) is the net normal stress.  
Figure 3: Effect of the saturation degree on the effective stress parameter \(\chi\).  
Figure 2: Soil–water characteristic curve.
## 1 Introduction  
Semiconductor lasers subjected to external optical feedback usually produce rich nonlinear dynamics, including periodic oscillations, quasi-periodic oscillations, and chaotic oscillations [1]. Among these dynamics, chaos is the most well-known and has been used for applications of secure communication [2, 3], random bit generation [4, 5], Lidar systems [6], and reservoir computing networks [7, 8]. One type of periodic oscillations, called period-one (P1) oscillations, have also been widely investigated. The P1 oscillations of common laser diodes originate from the undamped relaxation resonance oscillation and exhibit a sinusoidal-wave-like waveform [9, 10, 11, 12]. Therefore, the P1 oscillations have been explored for the generation of high-frequency photonic microwaves. In comparison with common quantum well lasers, mid-infrared quantum cascade lasers (QCLs) are found to be highly stable against optical feedback due to their picosecond carrier lifetime [13, 14, 15]. Our previous work significantly narrowed the spectral linewidth of a QCL, based on its high stability, by using strong optical feedback [16]. However, QCLs with optical feedback did produce low-frequency fluctuations, or chaos, under peculiar operation conditions, such as near-threshold pump current, pulsed pump current, and low operation temperature [17, 18, 19, 20]. Interestingly, a secure communication link using the chaos of a QCL has been demonstrated at a bit rate of 0.5 Mbit/s [21]. Our recent work found that QCLs can be more easily destabilized by using tilted optical feedback, where the reflection mirror is misaligned from the optical path [22]. In this configuration, we have observed periodic oscillations, quasi-periodic oscillation, and low-frequency oscillations at different mirror-tilt angles [22, 23].  
QCLs have been employed for gas sensing applications using a large variety of spectroscopy techniques [24]. Among these techniques, the modulation spectroscopy requires a sinusoidal modulation of the laser sources, including wavelength modulation spectroscopy (WMS) [25], frequency modulation spectroscopy (FMS) [26], and heterodyne phase-sensitive dispersion spectroscopy (HPSDS) [27; 28]. The QCLs are usually modulated by direct current modulation or by external modulation using modulators [27; 29; 30; 31] with modulation frequencies ranging from kHz up to several GHz [25; 26; 27; 28; 29; 32]. Since the P1 oscillations also modulate the light in a sinusoidal waveform, this modulation might be helpful for developing modulation spectroscopy systems. Motivated by the above applications, this work investigates the modulation characteristics of P1 oscillations in a QCL with tilted optical feedback. It is found that the electrical signal induced by the P1 modulation is 50 to 65 dB higher than the noise level, and the modulation depth is in the range of 1% to 3.5%. The electrical linewidth is less than 2.0 kHz, although the optical linewidth of the free-running QCL is as high as 16 MHz. In addition, we also numerically demonstrate that the P1 oscillations also induce frequency modulation due to the phase-amplitude coupling effect.
## 4 Conclusions  
The current study explores the possibility of applying the AFSD technique to build continuous multilayered AA7075-T6 parts on the AA2024 substrate, as well as to optimize the process parameters in terms of rotation speeds (200-1200 rpm) and deposition feed rates (1-5 mm/min). The macrostructures, microstructures, present phases, and mechanical properties were investigated. Based on analysis of the results, the following conclusions can be drawn:  
1. The suggested AFSD process successfully fabricated sound continuous multilayered AA7075-T6 DPs without any physical defects (porosity or cavities) using a 400 rpm rotation speed and 1, 2, 3, and 4 mm/min deposition feed rates.
2. The microstructure investigation showed that the AFSD at the applied deposition parameters produced equiaxed fine grain structures compared to the AA7075-T6 rod BM, and the optimum parameters for manufacturing deposited high-performance materials were found to be a CRRS of 400 rpm and a deposition feeding rate of 3 mm/min.  
Figure 15: Compressive stress-strain curves for the AA7075-T6 BM and the DPs processed at different deposition conditions.  
3. The chosen AFSD technique with the applied processing variables gives a more uniform hardness distribution through the cross-sections of the AA7075-T6 deposited materials compared to the AA7075-T6 rod BM.
4. The deposition feed rate affects the size and dispersion of intermetallics (MgZn2, Al-CuMg and Al7 Cu2 Fe) at a CRRS of 400 rpm, and the obtained results demonstrate that these precipitates have a direct impact on the strengthening of the deposited layers.  
Conceptualization, M.M.E.-S.S., A.B., M.M.Z.A., I.A. and Y.G.Y.E.; methodology, M.M.E.-S.S., Y.G.Y.E., M.M.Z.A. and A.B.; software, A.B., Y.G.Y.E., A.A.-S. and S.A.E.; validation, A.B., M.M.E.-S.S., M.M.Z.A., R.R. and Y.G.Y.E.; formal analysis, M.M.E.-S.S., M.M.Z.A. and R.R. investigation, I.A., A.B. and Y.G.Y.E.; resources, M.M.E.-S.S., A.B. and M.M.Z.A.; data curation, M.M.E.-S.S. and A.B.; writing--original draft preparation, Y.G.Y.E. and R.R. writing--review and editing, A.B., M.M.E.-S.S., M.M.Z.A. and I.A. visualization, I.A.; supervision, M.M.E.-S.S.; M.M.Z.A. and A.B. project administration A.B. funding acquisition, A.B. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the Deanship of Scientific Research at Umm Al-Qura University for supporting this work by Grant Code: (23 UQU4331139 DSR003).  
Not applicable.  
Data Availability Statement: Data will be available upon request through the corresponding author.  
The authors would like to thank the Deanship of Scientific Research at Umm Al-Qura University for supporting this work by Grant Code: (23 UQU4331139 DSR003).  
The authors declare no conflict of interest.  
References