esa-sceva/satcom-chunk-collection huggingface dataset:
# Framework for Video Steganography Using Integer Wavelet Transform and JPEG Compression
## 6 Conclusions and Future Scope  
Currently, steganography techniques are most commonly used for the security of personal information. However, these techniques have many issues associated with them. Some of the most common issues with these techniques are low concealing capacity, poor visual quality of the stego file, and robustness against attacks. IWT along with JPEG compression-based video steganography technique is used in this paper to overcome the mentioned issues. Video cover file help to improve concealing capacity whereas IWT help to improve robustness and visual quality. The robustness of the proposed work is checked through Gaussian and gamma correction attacks. SSIM, MSE, PSNR, and CC are calculated for imperceptibility check. For complexity, we calculated the concealing and retrieval time of the proposed work. Concealing capacity is calculated as 34 BPS. A comparison of the proposed work is also done with the existing work.  
Due to the growth of advanced technologies, security of online transmission of information is becoming more difficult. Moreover, there are users which are not aware about new technologies. Many smart hackers are also there, who are much more aware of the advanced technologies. So, the huge gap between the skills of hackers and innocent users makes the requirement of safe online communication more aspirational as well as demanding. Still there are many issues which are associated with steganography techniques. The proposed research work could be extended with some encryption techniques, which will provide more security but at the same time complexity can be increased.  
Conceptualization, R.T. and U.P.; methodology, M.Z.; writing--original draft preparation, U.P.; writing--review and editing, R.T.; supervision, A.A.M. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Not applicable.  
The authors declare no conflict of interest.
# Organic Crystals for THz Photonics
## 2 Second-Order Organic Nonlinear Optical (NLO) Crystals
### Optical and NLO Properties of Organic Crystals
#### 2.3.1 Ionic Organic Crystal DAST  
DAST is the most well known and widely investigated organic electro-optic crystal. DAST was first reported already in 1989 by [41; 42] and is still being recognized as one of the best state-of-the-art  
Figure 4: Crystal structures and the dominant sample morphology of some of the most well investigated organic NLO crystals for THz-wave generation during the last decade: the stilbazolium salts DAST (**a**) [41; 42; 43; 22] and DSTMS (**b**) [32; 44], the non-ionic configurationally locked polyene crystal OH1 (**c**) [45; 46] and the quinolinium salt HMQ-TMS (**d**) [47]. The structures are available at the Cambridge Crystallographic Centre (CCDC) for the corresponding publications. The red arrows indicate the direction of the main charge-transfer axis of the NLO chromophores. The typical plate-like sample morphologies used in THz applications (as-grown for DAST, DSTMS, OH1 and cleaved for HMQ-TMS) have been drawn based on the information given in the corresponding references. organic NLO crystals. High optical quality and large size DAST crystals can be grown from methanol solution by the slow cooling method [43; 48]. DAST crystals have high second-order NLO and electro-optic coefficients, being respectively ten times and twice as large as those of the inorganic standard LiNbO\({}_{3}\). Due to the relatively low zero-stress relative permittivity compared to inorganic alternatives, as discussed in the previous section, DAST is highly attractive for high-speed electro-optic applications and broadband THz-wave generation [22]. DAST is an organic salt that consists of a positively charged stilbazolium cation and a negatively charged tosylate anion. The stilbazolium cation is one of the most efficient NLO active chromophores that can crystallize in a non-centrosymmetric structure [15; 30]. The counter ion tosylate is used to promote the non-centrosymmetric crystallization, but its contribution to the macroscopic nonlinearity is negligible compared to the cation [41; 49]. \begin{table}
\begin{tabular}{l l l l l l l l} \hline \hline
**Crystal Name** & **Space Group** & \(\mathbf{\lambda_{\text{max}}}\) & \(\mathbf{\beta_{zz2}}\) & \(\mathbf{\theta_{kz}}\) & \(\mathbf{\beta^{\text{eff}}_{ijk}}\) & \(\mathbf{d_{ijk}}\), \(\mathbf{r_{ijk}}\) \\
**[Refs.
# Tuning the Cell and Biological Tissue Environment through Magneto-Active Materials
## 4 Fundamentals of Smart Polymeric Materials: Focus on Magneto-Active Elastomers and Hydrogels
### Magneto-Active Hydrogels  
In the field of smart polymeric materials, magnetic interaction is an especially good candidate for actuation due to its biocompatibility, even at relevant high fields, as well as to the fact that magnetic fields can provide this actuation in a remote manner [133]. Hydrogels capable of responding to the absence or presence of a magnetic field are known as magneto-responsive hydrogels. These are composed by inorganic magnetic nanoparticles (MNPs), which are physically entrapped in a hydrogel (by using the blending method or in situ precipitation method), or covalently immobilised to a hydrogel network (by using the grafting onto method). Magnetoactive hydrogels are, therefore, the combination of hydrogels with micro- and/or nano-sized magnetic particles that can quickly respond to an external magnetic field (EMF) [134].
## 4 Results and Discussion
### KLSVM Model Implementation  
Using Python's sklearn library, the support vector classifier (SVC) was computed with \(C=1\) as regularization parameter, and gamma \(=1\) and _decision_function_shape = 'ovr'_ as the one-versus-all multi-category classification technique for the linear kernel. For our implementation design (see Figure 7), we used _model_fit()_ as an effective method for inputting all the labels (link quality estimates), fitting linear feature data and training the data. The results returned are the optimal values for the parameters. The method _model_predict()_ was also used as our prediction model that functioned as an extension to the generic algorithm.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Link Type** & **Number of Links** & **Percentage** & **Average Retransmission Cost**1  \\ \hline Very Good Link & 49 & 12.25\% & 0.1015077 \\ Good Link & 93 & 23.25\% & 0.309878 \\ Intermediate Link & 181 & 45.25\% & 0.729711 \\ Bad Link & 63 & 15.75\% & 1.914515 \\ Very Bad Link & 13 & 3.25\% & 63. 272 2 \\ Faulty Link & 1 & 0.25\% & N/A \\ \hline \hline \end{tabular}
\end{table}
Table 1: Average retransmission cost.  
Figure 6: NGMI’s ceiling: Part of the 4 \(\times\) 5 WSN testbed.
## 3 Results
### Coupling and Coordination of GSI Systems
(**a**) Quadrant-based typology derived from CD and CCD indices; and (**b**) spatial distribution of districts by quadrant classification in the GBA. A total of 266 districts fall into the third quadrant, \"Not Coupled and Not Coordinated\", signaling critical misalignments between GSI infrastructure and local needs. These include substantial clusters in Zhaoqing (76 districts), Huizhou (37), Guangzhou (94), and Jiangmen (26). For instance, in Guangzhou--an urban core with high population and building density--green space provision has lagged behind rapid development, resulting in pronounced supply-demand imbalances. On the other hand, 62 districts are classified under the first quadrant, \"Coupled and Coordinated\". These are primarily located in Shenzhen, Macao, and Hong Kong, where urban design integrates GSI systems effectively into the built environment and planning priorities. The quadrant-based approach facilitates identification of regions with either underutilized ecological potential or uncoordinated infrastructure expansion. Several districts have constructed substantial GSI systems without an adequate understanding of local demand, while others have developed rapidly without incorporating sustainable stormwater management.
## 3 Results
### Spatial Distribution Characteristics of TCWV in China
#### 3.1.3 EOF Analysis of TCWV Spatial Distribution in China  
To further study the spatiotemporal variations of the TCWV, an EOF analysis was performed on TCWV from the AIRS dataset to identify the dominant modes of year-to-year variation. The spatial distribution of the three leading EOF modes and their corresponding time series are presented in Figure 3. This shows that the cumulative variance contribution rate of the first three modes of EOF analysis of TCWV is 59.73%, that is, the change information of the first three modes representing the original variable field is 59.73%. Therefore, the spatial distribution of the first three eigenvectors can represent the main distribution type of the TCWV throughout the year. The first three modes of EOF were mainly analyzed as follows. Figure 3a shows that the first EOF mode of TCWV variation accounts for 31.47% of the total variance during 2003-2021, indicating that the TCW has good convergence in space. The TCWV values of the first spatial mode of EOF is positive in most areas except for the southwest border, which is basically the inverse northwest-southeast type. From Figure 3c, the second spatial mode of EOF analysis value of TCWV is low in most areas except for the northeast of China, indicating the consistency of TCWV distribution in China. From Figure 3e, the value of TCWV of the third spatial mode of EOF presents a 'positive-negative' pattern from south to north and the maximum on the Tibetan Plateau. In addition, the time coefficient corresponding to the feature vector represents the time variation characteristics of the distribution pattern characterized by the feature vector in the region. The results of the first temporal mode and the third temporal mode of EOF analysis demonstrate that TCWV has shown similar increasing trends over the past 19 years (Figure 3b, f) except for the second temporal mode of the TCWV of EOF (Figure 3d).  
Figure 2: TCWV of China in each season. (**a**) Winter. (**b**) Spring. (**c**) Summer. (**d**) Autumn.
# Calculation Method of Earth Pressure Considering Wall Displacement and Axial Stress Variations
## 1 Introduction
[PERSON] [46] and [PERSON] [47] postulated a linear relationship between passive earth pressure and retaining wall displacement, which led to the development of predictive models for earth pressure under different displacement modes. [PERSON] [48] assumed a planar damage surface with constant shear strain along the slip plane, but this assumption does not adequately represent the actual behavior during the displacement process. [PERSON] [49] assumed that the stress in the soil behind the wall along the axial direction of the wall is the static earth pressure, which is different from the actual situation. A review of the relevant literature indicates that most of these studies have certain limitations. Those studies that can consider different displacement modes and are applicable to both clay and cohesionless soils are comparatively rare. In this study, a finite displacement earth pressure calculation method is developed by applying the non-linear elasticity theory under the assumption that the soil behind the wall is in a plane strain state, while also considering the axial stress changes during the wall displacement. Based on the different directions of principal stress behind the wall, three special earth pressure points are derived. The conditions for the existence of the minor principal stress second inflection point were investigated. Subsequently, the earth pressure behind the wall was categorized into different regions by incorporating the limit earth pressure points. According to the distribution characteristics of the wall displacement, formulas for calculating the earth pressure under different displacement modes are presented. The soundness of the proposed method is validated by numerical simulations and existing model tests.
## 2 Materials and Methods
### Testing Procedures
#### 2.2.3 Single-Leg Countermovement Jump Kinematic Analysis  
The technical execution of movements was recorded with two Panasonic DMC-FZ200 cameras (Panasonic Corporation, Kadoma, Osaka, Japan) at a capture frequency of 100 Hz. All jumps were captured in both the frontal and sagittal planes. The cameras were positioned at a 1 m height, 3 m sagittally or frontally relative to the participants. Video recordings were analyzed with Kinovea software (Version 0.9.5, Kinovea Open-Source Project, www.kinovea.org, accessed on 4 March 2024). The reliability and validity of the software for obtaining kinematic parameters had been previously verified [26]. When imported to the software, the video recordings of the SLCMJs were calibrated in 2D space with a Line tool in Kinovea software using the 0.3 m high vertical edge of the wooden box as a reference object, which was placed 0.05 m behind the force plates. Before conducting the 2D kinematic analyses, the video recordings of the SLCMJs were time-synchronized with the vertical component of ground reaction force (GRF). The time point of the GRF where the unloading phase for the SLCMJs started was synchronized with the start of the downward movement of the marker placed over the greater trochanter by visual inspection with a precision of 0.01 s.  
Kinematic variables were analyzed in the order from proximal to more distal segments. They were calculated at the time point of the peak vertical GRF during the jump (Figures 2 and 3). This was based on the understanding that the center of mass reaches its lowest vertical position when the GRF is at its peak [30], representing the most challenging phase of the jump for the musculoskeletal system. The \"Stopwatch\" module in Kinovea software was used to track the time from the initiation of the movement to the peak GRF time point. The Angle tool in Kinovea software was employed to measure the inclination of body segments relative to the vertical or horizontal planes (absolute kinematic variables) and joint angles--the angles between two adjacent body segments (relative kinematic variables). The markers were zoomed in to the maximum extent to improve the accuracy of the manual measurements. The absolute kinematic variables presented a moderate to good reliability between three jump repetitions (ICC = 0.605-0.795), apart from shin inclination in the sagittal plane (ICC = 0.492). The relative kinematic variables presented a poor to good reliability (ICC = 0.188-0.772). Schematic illustrations of the absolute and relative kinematic variables are presented in Figures 2 and 3.  
Figure 2: Presentation of relative (**a**) and absolute (**b**) kinematic variables in the sagittal plane.
## 3 Results Analysis and Discussion
### The Effect of Fiber Length on Soil Behavior  
In this study, glass fiber and macromesh fiber were used in two different lengths of 24 mm and 48 mm, and the effect of the length of the fibers on the bearing capacity was investigated. In order to examine the effect of fiber length on ultimate bearing capacity, 36 experimental groups were evaluated. Looking at the results, it was observed that the increase in fiber length increased the ultimate bearing capacity in both glass fiber and macromesh fiber added tests and glass + macromesh fiber added tests. [PERSON] et al. [24] and [PERSON] et al. [55], in their previous studies, stated that the increase in fiber length positively affects the carrying capacity. Fiber length affects the reinforcing effect by affecting the contact area, but this effect is relatively small compared to the fiber content. In addition, [PERSON] et al. [56] reported that the increase in carrying capacity with the increase in fiber length was associated with the surface morphology of the fiber. When glass fiber and macromesh fiber are compared among themselves, it was observed that the macromesh fiber-reinforced soil bearing capacity increased more as a result of the increase in fiber length. As seen in the experimental study, since the outer surface of the macromesh fiber is rougher than the glass fiber, the resistance created on the surface of the fiber increased as the fiber length increased. As the fiber length increases, the bonding and friction force between the fiber and soil grains increases, and the bearing capacity increases. The shear strength of the soil increases due to the tensile force formed as a result of the friction force between the fiber and soil grains. [PERSON] et al. [57] said that the bridging effect of the fibers increases as the fiber length increases. According to [PERSON] et al. [58], their study reported that when exposed to an external force, the effect between fibers of different lengths and the soil takes different forms of failure. When the fiber length is short, the failure patterns are characterized by shearing or slipping of the fiber. As the fiber length increases, the failure patterns are characterized by fiber breakage. However, excessively long fiber makes uniform fiber distribution in soil difficult. Because, in long fibers soil, this can cause agglomeration and uneven distribution. As a result, when the length of the fibers used to strengthen the soil is extended, more energy must be spent for a certain deformation to occur in the soil. When the experimental groups were examined among themselves, the effect of fiber length was seen mostly in the tests (49%) reinforced with Dr = 50%, Fc = 2%, glass + macromesh fiber at 2B depth, and it was seen in the tests (48%) reinforced with Dr = 30%, Fc = 2%, macromesh fiber at B depth, and it was seen in the tests (40%) rein-forced with Dr = 50%, Fc = 2%, glass fiber at 3B depth.
# Small-Satellite Synthetic Aperture Radar for Continuous Global Biospheric Monitoring: A Review
## 4 Applications of Small Satellite SAR Data
### Coverage Enhancement with Small SAR Constellations  
Large SAR spacecraft has more functionalities than small satellites. For example, the NISAR mission, a NASA-ISRO joint Earth-observing initiative planned for launch in 2021, will for the first  
Figure 21: Ka-band SAR in various size scales: (**left**) RainCube nanosatellite. (**right**) Surface Water and Ocean Topography (SWOT) satellite. Source: JPL/NASA, CNES.  
time use dual radar frequencies (L-band and S-band) in a single spacecraft. Having rich flight heritage since the Seasat mission in 1978, NASA will provide the L-band (24 cm wavelength, 1.25 GHz) SAR while ISRO will provide the S-band (9.3 cm wavelength, 3.20 GHz) SAR, the satellite bus, and launch services [124]. Figure 22 (left) illustrates the instruments of NISAR. The S-band SAR with a shorter wavelength is more sensitive to light vegetation than the L band, which penetrates leaves to reveal core structures. Figure 22 (right) is a pictorial description of the mission's versatility. One can easily assume that the operation of such spacecraft will be tightly scheduled to allocate its resources to vast areas for different purposes. Equatorial regions are especially difficult to observe frequently because ground swaths become sparser. These spatiotemporal gaps can be first remedied by small satellites that can be launched in multiples and may use non-Sun-synchronous orbits (inclined orbits) [125]. Table 8 takes NovaSAR as an example in which an assumed equatorial orbit significantly reduces the revisit time than a Sun-synchronous orbit. The resolution and the frequency bands of small-satellite SAR are comparable to NISAR or Tandem-L, only falling behind in swath width.
## 5 Conclusions  
Within the limitation of this study, conducted tests show the potential of a novel friction-based lateral screw retention method. The coping design in this study combined the advantage of the cement-retained and vertical screw retention method. This design gives an ideal occlusal advantage, better aesthetics, and is retrievable. This study shows that particle size positively correlates with surface roughness in the sandblasting process of titanium dental abutments. Aside from that, surface roughness was also found to be a critical factor that positively correlates with retention force. Sandblasting on titanium dental abutments using Al\({}_{2}\)O\({}_{3}\) with 686 \(\upmu\)m particle size (highest particle size used in this study) under 0.3 MPa pressure from a 10 mm distance in 10 s resulted in the highest surface roughness (R\({}_{a}\)) of 0.67 \(\pm\) 0.04 \(\upmu\)m and a retention force of 317.87 \(\pm\) 21.08 N; these sandblasting conditions were then used in the following experiment as the standard sandblasting conditions.  
In order to understand the human capability to produce tightening torque for this novel friction-based lateral screw retention, an experiment was conducted under simulated conditions. The jig with a 40.5 mm mouth opening and conditions similar to lateral screw tightening in the second molar shows an average of 69.75 Nmm with a standard deviation of 22.91 Nmm.  
Using sandblasting parameters and considering variations of tightening torque from the previous experiment, the novel friction-based lateral screw retention was tested under variations of tightening torque, namely 69.75, 120, and 200 Nmm. The result of this experiment is promising for the possibility of this novel crown retention method. The retention force of SB686 T69.75 gives the lowest value of 96.67 \(\pm\) 16.66 N, which is significantly lower compared to CR groups (\(p\) < 0.01). The SB686 T120 average is 158.48 \(\pm\) 23.37 N, which is insignificantly different compared to CR with 155.83 \(\pm\) 19.85 N. Lastly, SB686 T200 shows a significantly higher result of 317.87 \(\pm\) 21.08 N compared to CR (\(p\) < 0.01). This phenomenon, combined with the tightening capability of this study's subject, proved that tightening torque can have a significant impact on coping retention in this method.  
Even though the result of this study shows it can be one of the solutions to today's crown retention methods, there is still much room for improvement, and studies need to be conducted to explore the full potential of this novel retention method.
# Miniaturized PIFA for 5G Communication Networks
###### Abstract  
This paper designed a miniaturized Planar Inverted-F Antenna for 5G communication networks, including Long-Term Evolution Advanced mobile communication services. By showing the radiation pattern, voltage standing wave ratio, and antenna gain of the designed Planar Inverted-F Antenna, this paper evaluates its performance. To show the key characteristics of the Planar Inverted-F Antenna, this paper modeled and simulated it with various variances. Moreover, the real Planar Inverted-F Antenna was fabricated and measurements were done to validate the simulated characteristics of the internal antenna.  
antenna; PIFA; LTE; 5G; communication +
Footnote †: journal: Applied Sciences
###### Abstract  
This paper investigates the potential for interference from multipoint video distribution systems (MVDS) transmissions, specifically side lobe radiation in Lebanon, to geostationary Earth orbit (GEO) satellites. Through simulation and analysis of antenna radiation patterns, the impact of varying MVDS power levels on the carrier-to-noise ratio (C/N) at the satellite receiver is quantified. The results demonstrate a significant degradation in signal quality, with the C/N dropping to \(-2.29\) dB at an MVDS power of \(0\) dBW for the current system. To mitigate this interference, a two-step potential strategy is proposed and evaluated. The study boosts the potential for the coexistence of MVDS and GEO satellite services in the Ku-band within the Lebanese context.  
MVDS; GEO satellites; Ku-band; interference; side lobe radiation; Lebanon Article