esa-sceva/satcom-chunk-collection huggingface dataset:
# Influence of Incident Shock on Fuel Mixing in Scramjet
###### Abstract  
During the operation of hypersonic vehicles, a reciprocal coupling effect is manifested between the inlet and the combustion chamber. This results in an unavoidable non-uniformity of conditions at the combustion chamber's entrance, which, in turn, influences the fuel mixing within the chamber. The present study employed the Reynolds-averaged Navier-Stokes (RANS) equations to perform a numerical simulation of an X-51-like vehicle, with a focus on examining the impact of isolation section length and multi-injection strategies on the fuel mixing characteristics within the combustion chamber under conditions of non-uniform inflow. The findings indicated that a supersonic non-uniform inlet triggers incident shock waves, leading to a non-uniform pressure distribution across the flow section. Moreover, the position of injection was found to be pivotal in regulating penetration depth and mixing efficiency. The incident shock wave, bow shock, and boundary layer separation shock interacted with each other to increase local pressure. The coupling of high and low pressures generated an adverse pressure gradient that led to boundary layer separation, which further enhanced fuel penetration depth.  
non-uniform inflow; incident shock wave; transverse jet; X-51-like vehicle
## 3 Materials and Methods
### System Implementation and Integration  
#### 3.4.1 Hardware and Software Tools  
There is varying hardware and software utilized in the development of the Dr. Barea system, including:  
* 3D Virtual Reality Helmet, (VR Shinecon, Mainland China)--used to test and view the 360\({}^{\circ}\) VR video.
* Samsung Galaxy A71 (Samsung Electronics, Suwon, Republic of Korea)--an Android smartphone used for running and testing the project.
* insta360 Camera, (Shenzhen, China)--special camera to take 360\({}^{\circ}\) video.
* Canva (version 3.0, Windows, Canva, Sydney, Australia) [36]--a platform used to create social media graphics, presentations, posters, documents, and other visual content.
* Procreate (version 5.3.1, iOS, Savage Interactive Pty Ltd., North Hobart, Tasmania, Australia) [37]--a raster graphics editor app for digital painting.
* Scanner (PTC. INC., Boston, MA, USA) [38]--used to scan 3D objects.
* Visual studio (version 17.0, Windows, Microsoft, Redmond, WA, USA) [39] Atom (San Francisco, USA) [40]--used to write the scripts.
* Insta 360\({}^{\circ}\) One X (Android, Insta360, Los Angeles, CA, USA) [41]--used to view and edit the shots in 360\({}^{\circ}\).
* Unity hub (San Francisco, CA, USA) [42]--a tool to manage all the projects that have been uploaded by the team in the cloud.
* Unity (San Francisco, CA, USA) [43]--a cross-platform engine used to develop games, VR, and AR applications.
* Vuforia (PTC. INC., Boston, MA, USA) [44]--software version 10.14. for creating augmented reality for mobile devices.  
Figure 5: Sequence diagram of “Scan Dental Tools” function.
# mmHSE: A Two-Stage Framework for Human Skeleton Estimation Using mmWave FMCW Radar Signals
## 5 Experimental Results and Analysis
### Cross-Domain Experiment  
To evaluate the generalization capability of the proposed mmHSE model, we conduct experiments under both cross-domain (CD) and cross-user (CU) settings. Specifically, CD_1 refers to training on data collected in a meeting room, CD_2 corresponds to a hallway environment, and CD_3 represents open space scenarios. The CU setting involves training on data from two participants and testing on previously unseen users. Evaluation is conducted along three spatial axes--horizontal, vertical, and depth--using both MAE and RMSE as performance metrics. The results are illustrated in Figure 9.  
In the cross-domain setting, mmHSE demonstrates consistently low and stable localization errors across all domains. The average MAE for CD_1, CD_2, and CD_3 are 3.34 cm, 3.17 cm, and 3.14 cm, respectively, with a maximum deviation of only 0.20 cm. This stability underscores the effectiveness of the proposed spatiotemporal modeling strategy and dual-radar fusion mechanism in adapting to diverse environmental conditions. Notably, performance improves progressively from CD_1 to CD_3, suggesting that the model benefits from domain-agnostic learning and generalizes well to previously unseen distributions.  
In contrast, the cross-user setting poses a greater challenge. The average MAE increases to 3.86 cm, reflecting a relative degradation of 22.9% compared to the best-performing cross-domain configuration. A similar trend is observed in RMSE, which rises from 5.27 cm in CD_3 to 5.99 cm in CU. The most pronounced degradation occurs along the depth axis (MAE = 5.11 cm, RMSE = 7.34 cm), likely due to user-specific variations in motion style and body morphology that are harder to generalize across subjects.  
Despite these challenges, mmHSE maintains relatively low and stable errors in the horizontal and vertical directions across all scenarios, typically within the 2.5-3.2 cm MAE range. These results indicate that while the proposed model offers strong generalization  
Figure 8: MAE and RMSE errors for the 21 skeletal keypoints under the mmHSE. (**a**) represents the MAE error, and (**b**) represents the RMSE error.  
across different domains, future work may focus on improving robustness to inter-user variability, particularly in depth estimation.
# Passive Earth Pressure and Soil Arch Shape: A Two-Dimensional Analysis
## 1 Introduction
In practical applications, achieving a fully mobilized passive state requires wall displacement, yet, in most cases, movement is insufficient, resulting in earth pressure values between at-rest and passive states. To address this, studies have explored non-limit state passive earth pressure, incorporating displacement effects for more accurate predictions [18; 19]. Meanwhile, limit analysis has also gained traction. For instance, [PERSON] [20] derived the magnitude of passive earth pressure under seismic action using the upper-bound analysis, further exploring the effects of factors like backfill height and internal friction angle on wall stability. Significant progress has been achieved in calculating passive earth pressure using the horizontal layer method coupled with the soil arching effect, enabling reasonable descriptions of its distribution patterns to some extent. However, several limitations persist: (1) no consensus exists on soil arching shape (major principal stress trajectory) under passive limit equilibrium, with conflicting convex and concave assumptions that often misalign with observed behavior; (2) the assumption that all points in the sliding wedge are at limit equilibrium contradicts observations; (3) shear stress induced by principal stress rotation is often overlooked, leading to discrepancies in predicted earth pressure distribution. To address these limitations and improve the estimation of passive earth pressure, this study adopts a two-dimensional differential element approach. An arbitrary element dxdz within the sliding wedge is selected as the basic unit for analysis (see Figure 1b). This approach avoids the assumption of soil arching shapes and accounts for the effects of shear stresses. By solving the equilibrium differential equations under reasonable assumptions and boundary conditions, analytical stress solutions are derived for any point within the wedge. Based on these solutions, the magnitude, distribution, and point of application of passive earth pressure on the retaining wall are determined. Furthermore, the trajectory of the major principal stress is derived analytically and compared with the assumed trajectories adopted in previous studies. Finally, parametric analyses are carried out to explore the influence of key factors on passive earth pressure, and comparisons with theoretical and experimental results confirm the accuracy and applicability of the proposed approach.
## 3 Recent Trends in Hydrogen Storage: Gas, Liquid, Solid
### Latest Hydrogen Storage Technology
#### 3.2.2 Powerpaste  
The Leibniz Institute for Polymer Research Dresden (IPF) in cooperation with Dresden's Fraunhofer Institute for Manufacturing Technology and Advanced Materials (IFAM) developed new technology based on solid magnesium hydride in the form of a goop called POWERPASTE. This matter has an approximately 10% hydrogen capacity, which means that 1 kg of hydrogen weighs the same as 10 kg of POWERPASTE with a power range of 100 W to 10 kW. The hydrogen is released when POWERPASTE comes into contact with any specific type of water. It can use a variety of different water sources, including tap water and even salt water. This technology provides several advantages: (1) its composition is not toxic and is safe, and it may be transported without any special safety precautions or worries; (2) it has a 5-year storage life, making it a reliable and practical option for storing hydrogen; (3) it is easily recyclable and is produced at a low cost of roughly \(\copyright\copyright\copyright\copyright\copyright\copyright\copyright \copyright\copyright\copyright\copyright\copyright\copyright\copyright\copyright\copyright\copyright\copyright\copyright\copyright\copyright\copyright\copyright\copyright\copyright\copyright\copyright\copyright\copyright\copyright\copyright\copyright\copyright\copyright\copyright\copyright\copyright\copyright\copyright\copyright\copyright\copyright\copyright\copyright\copyright\copyright\copyright\copyright\copyright\copyright\copyright\copyright\copyright\copyright\copyright\copyright\copyright\copyright\]  
Figure 17. POWERPASTE-based power system [87].  
Table 5 presents a comparison between the plasma kinetics and POWER-PASTE technologies, highlighting their respective characteristics and performance metrics.  
Generating and storing hydrogen on a large scale is a challenge that requires additional study and development. Those technologies will become more widely available and cost-effective in the next few years, making hydrogen a more viable option for large-scale energy generation and storage. Table 6 provides a comprehensive summary of the advantages and disadvantages of the latest hydrogen storage technologies. It offers a concise overview of the strengths and weaknesses associated with each technology, allowing for a quick comparison and evaluation of their respective merits. By examining this table, readers can gain valuable insights into the various aspects that contribute to the effectiveness and feasibility of these storage methods, enabling them to make informed decisions based on their specific requirements and priorities.
## 2 Broken Rotor Bar in IMs
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Ref.** & **Fault** & **Signal Processing** & **Feature Index** & \begin{tabular}{c} **Mother** \\ **Wavelet** \\ \end{tabular} & \
\begin{tabular}{c} **Artificial** \\ **Intelligent** \\ \end{tabular} &
\begin{tabular}{c} **Disadvantages** \\ \end{tabular} \\ \hline
[14] & BRB & WPD & Feature coefficient & Coif 4 & \
\begin{tabular}{c} Artificial neural \\ network \\ \end{tabular} &
\begin{tabular}{c} Only one feature is extracted \& \\ Disordering of sub-band frequency \\ \end{tabular} \\ \hline
[21] & BRB & WPD & \begin{tabular}{c} Statistical feature \\ of wavelet \\ packet 1-d \\ \end{tabular} & Haar & \
\begin{tabular}{c} Adaptive \\ neuro-fuzzy \\ inference system \\ \end{tabular} &
\begin{tabular}{c} Only one mother wavelet is studied \& \\ Lack of BRB fault severity detection \\ \end{tabular} \\ \hline
[22] & Rotor & \begin{tabular}{c} WPD, Empirical \\ Mode \\ Decomposition \\ \end{tabular} & \begin{tabular}{c} Energy moment \\ of IMFs \\ \end{tabular} & Db 5 & \
\begin{tabular}{c} Multi-layer \\ feed-forward \\ neural network \\ \end{tabular} &
\begin{tabular}{c} Only one mother wavelet is studied \& \\ Only one feature is extracted \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table} 
Table 1: A summary on selected criteria for fault detection using WPD. stator winding and damage it. The small pieces come from a broken rotor bar also damage the stator windings and laminations during operation [25]. In addition to the secondary failures from broken rotor bar, mentioned above, this failure leads to a shaft vibration and thus air gap eccentricity [9]. Besides vibration, broken rotor bar also causes sparking and noise during the motor start-up and its normal operation [25; 32], which threatens the operation safety. It is evident that during start-up, more excessive vibration, more destructive sparking, and louder noise are generated. According to the explanation above, the effects of broken bar significantly lessen the efficiency and performance of electrical machines and early detection of this failure is essential [33]. Detection of broken rotor bar in its early ages not only secures the motor performance but also reduces risk of other types of failures. When the failure is at its early stage, symptoms of the faults are small and the motor apparently operates normally, therefore, the fault cannot be detected [10]. A relatively large number of studies have been performed on early detection of rotor faults, especially broken rotor bar, in squirrel-cage induction machines [1].
# Performance Analysis of DF Relay-Assisted D2D Communication in a 5G mmWave Network
## 2 System Model  
This section provides the system model for the proposed work along with the scenario description. Let us consider cellular and D2D users present in a cell communicating with each other in a 5G mmWave cellular network using an uplink channel through the assistance of a two-way DF relay protocol, as shown in Figure 1. The cardinality of cellular and D2D users may be denoted by \(N\) and \(M\), respectively. In this scenario, the cellular users utilize the uplink channel of the spectrum to communicate with the BS. The D2D users reuse the uplink resources of the cellular spectrum to communicate among each other. The cellular, as well as the D2D users are randomly distributed in the cell following a Poisson point process (\(PPP\)) \(\phi\) with densities \(\lambda_{c}\) and \(\lambda_{d}\), respectively, in a finite, two-dimensional plane \(\mathbb{R}^{2}\). The cell consists of two zones for communication to take place among D2D users, namely Zone 1 and Zone 2, respectively. Additionally, the proposed work portrays three modes of communication for seamless communication to take place.  
Mode 1: Direct D2D communication takes place at an operating frequency of 2 GHz in Mode 1 while satisfying the QoS constraints of the Zone 1 area.  
Mode 2: As the distance between the D2D users and the BS increases toward a certain predefined value, mode switching takes place from Mode 1 to Mode 2, where direct D2D communication occurs at a frequency of 28 GHz.  
Mode 3: In Mode 2, if the radius of coverage among the D2D users is greater than a certain predefined threshold, the SINR also reduces significantly. Thus, the data rate also diminishes, which results in a reduced QoS. Thus, to satisfy the QoS constraints and provide seamless operation among the D2D users, mode switching takes place from Mode 2 to Mode 3. The communication in Mode 3 takes place at a frequency of 28 GHz through the assistance of the conventional two-way DF relay node. The relaying occurs with the help of two time slots, \(T1\) and \(T2\), respectively.
# Additive Manufacturing of Variable Density Lenses for Radio Frequency Communications in X-Band
## 2 Dielectric Permittivity Measurements
### Microwave Characterization Methods
#### 2.1.1 Resonant Coaxial Biorentrant Microwave Cavity  
In the method described in [19], the measurements are based on how the resonant frequency and the quality factor of a resonant cavity change when a cylindrical sample of MUT is introduced into the cavity. The Single-post coaxial reentrant cavity is constructed using a coaxial transmission line, where a rod sample is introduced in a gap created in the inner conductor, Figure 1a. This cavity features a partially dielectric-filled gap and an endplate. To ensure alignment, a cylindrical tube housing the cylindrical sample of MUT is inserted through a hole in the endplate, see Figure 1b. It is then further inserted into the coaxial center conductor, which also serves to maintain concentricity. In order to perform the measurements a stand-alone microwave equipment, Dielectric Kit for Vials (DKV) from the Institute of Information and Communication Technologies (ITACA) settled in Valencia, Spain, which consisted of a Single-Post Reentrant Cavity for measuring cylindrical samples at resonance frequency of 2.45 GHz (mode \(TE_{111}\) is excited in the cavity without sample), as shown in Figure 2a, and a VNA are used. Measuring the reflection coefficient (\(S_{11}\)) of the cavity with and without the sample enables the extraction of the dielectric constant and the loss tangent. The procedure is described in detail at [20], where the circuital analysis of dielectric-loaded cylindrical waveguides and cavities is performed. The measurement equipment is detailed in [21].
# A Lightweight and Efficient Detection Transformer for Highway Abandoned Objects
## 3 Experimental Results and Performance Analysis
### Multi-Scale Kernel Design of the CMI Module  
Table 3 illustrates the effect of various convolution kernel configurations on the performance of the CMI module. The results show that using the 3 \(\times\) 3 kernel alone leads to poor performance due to its limited ability to extract texture information. The model employing the multi-scale kernel structure (5, 7, 9, and 11) attained optimal performance. Moreover, as the kernel size expands and the stride increases to 4, the parameter count and computational cost rise by 0.7% and 0.9%, respectively, whereas performance reduces by 3.8%. The findings indicate that larger convolution kernels may introduce background noise, subsequently impacting the model's performance. The kernel designs listed in Table 3 were inspired by the experimental configurations presented in [34].  
Next, we examined the effect of the number of convolution kernels in the CMI module, as illustrated in Table 4. The utilization of merely two convolution kernels (5 \(\times\) 5 and 7 \(\times\) 7)  
\begin{table}
\begin{tabular}{c c c c c c c} \hline
**Model** & **Epochs** & **Params (M)** & **FLOPs (G)** & **FPS (bs = 8)** & **AP50** & **AP50:95** \\ \hline YOLOv5-N & 125 & 1.8 & 4.2 & 685.2 & 77.5 & 33.3 \\ YOLOv5-N-RepELAN & 200 & 1.5 & 3.4 & 740.2 & 77.7 & 35.1 \\ \hline YOLOv7 & 200 & 36.5 & 103.3 & 66.5 & 81.6 & 39.2 \\ YOLOv7-RepELAN & 200 & 34.8 & 94.7 & 67.6 & 83.5 & 39.0 \\ \hline YOLOv8-N & 200 & 3.0 & 8.1 & 506.4 & 77.0 & 37.3 \\ YOLOv8-N-RepELAN & 200 & 2.2 & 6.1 & 601.8 & 77.6 & 37.2 \\ \hline YOLOv9-C & 200 & 50.7 & 236.7 & 37.2 & 78.7 & 38.9 \\ YOLOv9-C-RepELAN & 200 & 39.5 & 202.3 & 53.8 & 81.2 & 39.1 \\ \hline \end{tabular}
\end{table}
Table 2: Comparison between the original models and those with the feature extraction modules replaced by RepELAN, where the model with RepELAN in its name is the replaced model.  
\begin{table}
\begin{tabular}{c c c c} \hline
**Kernel Design** & **Params (M)** & **FLOPs (G)** & **AP50:95** \\ \hline \((3,3,3,3)\) & 14.4 & 44.7 & 41.6 \\ \((5,5,5,5)\) & 14.4 & 44.8 & 42.0 \\ \((7,7,7,7)\) & 14.5 & 44.9 & 41.4 \\ \((3,5,7,9)\) & 14.4 & 44.9 & 40.4 \\ \((5,7,9,11)\) & 14.5 & 45.0 & 42.6 \\ \((5,9,13,17)\) & 14.6 & 45.4 & 41.0 \\ \hline \end{tabular}
\end{table}
Table 3: Multi-scale kernel design.  
constrained the scale information obtained by the network. As the quantity of convolution kernels increased, the network's performance was enhanced, achieving optimal results with four kernels employed. However, when the number of kernels was increased to five, performance decreased. This suggests that larger or additional convolution kernels may introduce extra background noise or redundant features, which negatively affect the model's accuracy.
# Wound Dressing Materials: Bridging Material Science and Clinical Practice
## 4 Antimicrobial Dressings
### Silver-Based Wound Dressings  
Silver is widely recognized in dermatology for its effectiveness, particularly in treating burn-related wounds using silver sulfasalazine. The development of silver-infused dressings, such as foams, hydrofibers, and hydrocolloids, has broadened its application to various wound types, including those that are colonized or infected (Table 5) [76]. These silver-based dressings are commonly used for burns, ulcers, surgical wounds, and chronic wounds [77].  
Figure 3: Representation of the chemical structures of some synthetic polymers commonly used in wound dressings.  
As a heavy metal antiseptic, silver exhibits broad-spectrum bactericidal properties effective against both Gram-positive and Gram-negative bacteria, making it suitable for treating heavily infected wounds and cases involving drug-resistant bacteria [75]. Silver exerts its antimicrobial effects by damaging critical cellular components necessary for bacterial survival, including DNA/RNA, mitochondria, and enzymes involved in gene transcription and cell wall synthesis [75; 78].  
Silver dressings, such as Acticoat(tm), Actisorb(tm) Silver, Contreet Foam, Contreet Hydrocolloid, and SilverIon(tm), are highly effective in providing sustained antimicrobial activity for three to seven days. These dressings incorporate silver, a powerful antimicrobial agent, which helps control and reduce the microbial load within the wound. The prolonged antimicrobial effect is particularly beneficial in managing infections, as it continuously combats bacterial growth and prevents the development of resistant strains. These dressings are often used in situations where there is a significant risk of infection, such as in wounds associated with sepsis or bacteremia, as they help reduce the need for frequent dressing changes and support faster recovery. The use of silver dressings can also contribute to reduced hospitalization time for patients suffering from severe wound infections. By effectively controlling infection and supporting the healing process, these dressings can help prevent complications that would otherwise prolong recovery and lead to extended hospital stays. The ability to manage wound-associated sepsis and bacteremia with the sustained antimicrobial activity of silver dressings improves patient outcomes and offers a more efficient and cost-effective approach to wound care. As a result, these dressings have become a valuable tool in the treatment of complex, infected wounds, enabling quicker and more effective recovery [79]. However, due to silver's potential cytotoxic effects, which may inhibit fibroblast activity critical for wound healing, it is not recommended for infection prevention. However, silver dressings are safe for patients undergoing MRI scans of soft tissue and bone structures [80].