esa-sceva/satcom-chunk-collection huggingface dataset:
# Optimization of Laser-Assisted Polypropylene Aluminum Joining
## 3 Results and Discussions
### Testing  
#### 3.3.1 Microscopic Observation  
The results found from the DoE and the simulations must be observed under the microscope to confirm the approximations. Figure 11 shows the cross-sections of the laser-engraved Al samples with different parameters.  
Comparing different parameters presented in Figure 11 shows the influence of each one. While Figure 11a,b shows uniform teeth with 100 mm/s speed, and 25% engraving density, Figure 11c depicts a much more chaotic appearance where the molten PP will be hindered from properly flowing into. The low speed leads to promoting melting during the ablation process. Considering the evaporation of the material during the ablation process, deep grooves are achieved. However, melting is dominant; hence, cavities are formed by interfering with the molten material. A similar observation is present at the high density of the engraved lines (see Figure 12). The intersection between consecutive dot patterns results in processing the surface of Al several times at the overlapped locations. Consequently, in addition to deep grooves, cavities are formed, which are not open to the surface and, therefore, cannot be reached by the molten PP during the joining process.  
Figure 11: Microscopic observation of the engravement at the density of 25% and a speed of 100 mm/s (**a**); zoom on the teeth (**b**); at a higher density of 35% and a low speed of 5 mm/s (**c**); high-speed 200 mm/s and low density of 15% (**d**).  
In contrast, Figure 11d presents a sample with 200 mm/s speed and 15% laser engraving density. As observed, the combination of high speed and low engraving density results in a lower depth of engraving which reduces the mechanical interlocking and thus the shear load after the laser joining process.  
The depth of the cavities is almost double compared to that of the grooves, but they do not contribute to the joining process. As a consequence, Al is further weakened without any added benefit to the joined assembly and thus should be avoided.
## 4 In Situ Testing
### Evaluation and Assessment
#### 4.2.3 Identification of Modal Damping  
Modal damping is determined by the integration line of the peaks in the decay curve, as shown in Figure 11a. The damping ratio is evaluated using the mean value of several excitation points.  
Figure 10: Evaluation of the natural frequencies and associated modal shapes of frame bridge 12,842. (**a**) Time history of the ambient vibration velocity and averaged frequency spectrum. (**b**) Evaluation of 1 st eigenmode. (**c**) Evaluation of 2 nd eigenmode.  
The evaluation of small amplitudes induced by pulse excitation requires an undisturbed environment (verified by continuous wavelet transform) and a finely tuned measurement chain. In this case, the dissipation mechanisms turn out to be comparable to those observed for larger energy inputs, such as harmonic excitation or train crossings (not further explained). Considering the undisturbed environment, the four evaluation points result in a damping ratio of \(\zeta\approx 6.1\%\), matching to the first natural frequency. In comparison, the damping is calculated to be \(\zeta=6.3\%\) using the stochastic subspace identification algorithm implemented in the Artemis.  
In addition, damping was characterised on the basis of train crossings. Here, it is important to use the correct reference frequency. In this case, the 4-fold of the base train excitation is in the range of the natural frequency (\(4\times 2.5\) Hz), and therefore, the modal damping can be accurately determined to be \(\zeta_{train}=6.3\)-\(7\%\approx\zeta_{impulse}\).  
The assessment of damping ratios for higher modes follows a similar methodology, although a detailed description is omitted here.
# Fast Equipartition of Complex 2D Shapes with Minimal Boundaries +
## 4 2D-SEP Instances and Properties
### Plane Partition  
Firstly, we will consider the case of the partitioning of a plane into a high number of equal-area regions. Figure 4 shows three popular regular tessellation patterns (equal-area regions) that can tile a plane without overlaps or gaps: tessellations using (equal) hexagons, squares, or equilateral triangle. According to 2D-SEP, we examine the efficiency of the above three patterns in Table 1 by comparing the boundaries of an equal-area (\(s\)) hexagon, and square, and equilateral triangles as a function of \(s\). We find that tessellations using hexagons have 7% and 18.4% lower intrinsic boundary lengths compared to tessellations using square and equilateral triangles, respectively. Theoretically, _SEP-FBC_ and _SEP-RG_ are possible to generate hexagonal and square tessellations, while _SEP-ILS_ is possible to generate only equilateral triangle tessellations. Consequently, _SEP-FBC_ and _SEP-RG_ hold a theoretical advantage over _SEP-ILS_, a finding that is further supported by our experimental results.  
[PERSON] [30] gives proof that any partition of the plane into regions of equal area has a perimeter at least that of the regular hexagonal honeycomb tiling, meaning that the optimal solution of 2D-SEP when the number of regions is large enough is the partition into equal hexagonals.  
\begin{table}
\begin{tabular}{l l} \hline \hline
**Shape** & **Perimeter** \\ \hline hexagon & \(\frac{12\cdot\sqrt{s}}{\sqrt{3}}\approx 3.722\cdot\sqrt{s}\) \\ \hline square & \(4\cdot\sqrt{s}\) \\ \hline equilateral triangle & \(\frac{6\cdot\sqrt{s}}{\sqrt[3]{4}}\approx 4.559\cdot\sqrt{s}\) \\ \hline \hline \end{tabular}
\end{table}
Table 1: The perimeter of a hexagon, square, and equilateral triangle as a function of its area (s).  
Figure 4: Tessellations using (**a**) hexagons, (**b**) squares, and (**c**) equilateral triangles.
# Biomechanics of Punching--The Impact of Effective Mass and Force Transfer on Strike Performance
## 2 Materials and Methods
### Protocol
The non-punching hand remains high to protect the face, and after landing, the jab retracts swiftly to its original guard position. Crosses, also known as rear straight punches, are executed with the dominant hand and involve significant hip and torso rotation to generate maximum power. The movement starts from the rear foot, which pivots to drive energy upward through the hips and core. The torso rotates forcefully as the punching arm extends in a direct line toward the target. The fist remains vertical or slightly turned inward upon impact. A properly executed cross engages the entire body, ensuring efficient energy transfer from the lower body to the upper limb. Once the punch lands, it quickly retracts to the guard position to maintain defensive readiness. Lead hooks are powerful side punches executed with the lead hand. The movement begins with weight transfer to the lead leg and a subtle pivot of the lead foot. The torso rotates as the elbow lifts to shoulder height, positioning the arm at a roughly 90-degree angle. The punch travels in a curved motion, with the fist oriented either palm-down or palm-inward, depending on preference. The lead hook is highly effective at targeting the opponent's head or body, utilizing rotational force to generate impact. After making contact, the arm retracts back to the guard position. Rear hooks are delivered with the dominant hand and involve the entire body's engagement for maximum power. The technique starts with a weight shift onto the rear leg, followed by a strong pivot of the rear foot. The torso rotates explosively, guiding the arm in a wide arc. Like the lead hook, the elbow remains at shoulder height, and the fist orientation can vary. This punch is particularly effective for generating knockout power due to the full-body movement involved. Once the rear hook lands, it returns swiftly to the guard to maintain defensive positioning. All four techniques' execution is shown in Figure 2.  
Figure 2: Illustration of four recorded boxing techniques: jab, cross, lead hook, and rear hook.
## 1 Introduction
[PERSON], [PERSON], and [PERSON] examined cylindrical bio-inspired patterns [40] with a slicing strategy and build inclination factor. A finite element analysis (FEA) via ANSYS(r) software was used based on the coefficient of variation (COV) when the extrusion angle was not aligned with the build angle [41]. Figure 1: Schematic of FDM process. [PERSON], et al. [42] determined that porosity in samples at 60% infill density had the lowest strength. Besides, concentric and rectilinear patterns indicated the highest tensile strength in three directions, namely, flat, on the long edge, and on short edges. Moreover, [PERSON], et al. [43] investigated the influence of orientation, nozzle diameter, and infill percentage on SR in polylactic acid (PLA) samples. The lowest roughness with the value of 12.4 um was conducted for the flat angle, 0.2 mm nozzle diameter, and 5% infill density. In another study, [PERSON], et al. [44] studied infill patterns and realized maximum compressive strength for the Hilbert pattern with the value of 121.35 MPa. Average SR values were the lowest, at 1.14 um and 1.895 um for 20% and 80% densities for rectilinear pattern, respectively. [PERSON] and [PERSON] [45] proposed a novel method to combine solid, honeycomb, wiggle, grid, and rectilinear patterns in one dog-bone PLA sample to analyze their effects on tensile strength with different build orientations. In another study, the optimal condition was conducted in a sample with 0.5 mm layer thickness, 80% infill density and 65\({}^{\circ}\) raster angle by developing a mathematical model [46]. [PERSON], et al. [47] optimized honeycomb infill pattern in beam-shaped products by various EFA scenarios to achieve the strongest design and density. Moreover, [PERSON], et al. [48] showed that 80% infill density, 0.1 mm layer thickness and 40 mm/s printing speed were the appropriate conditions to achieve the best modulus of elasticity and ultimate tensile strength. While FDM 3D printers are capable of generating infill patterns with different densities, designing patterns using CAD software packages has not been investigated yet. The main aim of this study is to address this research question and make a comparison between infill patterns with various densities generated by CAD and FDM printer in dog-bone shape PLA parts. Besides, EFA is used to understand the behavior of interlayers under tensile strength and find out the differences between printed and simulated CAD samples. The effects of generated patterns by CAD on SR and mechanical properties were examined. Then, CAD patterns were compared to the printed specimens by the FDM machine. Four patterns with different percentages of infill density were chosen due to their capabilities in being strong under different loads. The strength and SR analysis of these two batches were examined to find out the differences.
## 4 Results and Discussions  
### Operational Force  
As mentioned in Section 3.2.2, the operational forces applied to the linking joints are calculated from the acceleration of those points in the operational mode. These data are collected with tri-axial accelerometers, and the modulus of acceleration is calculated for each point. Figure 7 illustrates the resultant operational force spectra acting on the linking points. There are three linking points on each side of the aircraft. These points connect the wings to the fuselage. The locations of these points are shown in Figure 5.  
Figure 6: Decay rate method for calculating the damping loss factor.  
Figure 7: Operational forces at the structural linking points.  
This figure shows that the forces applied from the wings to the fuselage are similar on both sides of the tiltrotor. These forces' spectra are used as the boundary conditions in the SEA model to define the interior noise levels at the target points.
## 1 Introduction  
Balancing data access speed and storage density is a critical challenge in modern data storage technologies. Fast data access and high-density storage are increasingly essential requirements across various applications. While conventional high-bandwidth memory (HBM) solutions offer effective performance, they are prohibitively expensive and limited in capacity, presenting significant barriers to widespread adoption in large-scale deployments [1]. In contrast, NAND flash memory provides a compelling alternative due to its low cost and high storage capacity. By utilizing NAND flash memory instead of HBM, it is possible to achieve the necessary memory capacity without incurring prohibitive costs [2, 3]. Therefore, enhancing the bit density in NAND flash memory is crucial for advancing modern storage systems. To meet these demands, 3D NAND flash memory requires technological advancements to reduce device size and lower costs. However, the non-ideal threshold voltage (Vth) shift phenomenon, which occurs during the scaling-down process of existing memory arrays, negatively impacts the performance of flash memory [4, 5, 6].  
Recently, numerous studies have focused on changes in memory characteristics due to a decrease in oxide/nitride (ON) mold pitch to address process and device issues arising from an increase in the number of stacked layers [7, 8, 9]. As the ON pitch decreases, the distance between each word line (WL) diminishes, accelerating Z-interference degradation and reducing the cell's distribution margin [10]. Additionally, as the program speed decreases and program/erase (PE) window characteristics deteriorate, securing reliable characteristics becomes challenging due to the reduced cell's distribution margin. While there are many studies on this phenomenon of program speed reduction, most analyze characteristics by reducing oxide and nitride at the same proportion within the ON pitch [9].  
Consequently, there is a lack of a clear analysis on the intrinsic program, erase and read characteristics, and overall memory characteristics when individually scaling the spacer length (Ls) and gate length (Lg) corresponding to the oxide and nitride thicknesses. In this study, we conducted a comprehensive analysis of the factors affecting the memory window, Z-interference, and data retention while systematically reducing Ls and Lg at a given ON mold pitch. Furthermore, to mitigate the program speed slowdown and Z-interference degradation that inevitably occur due to ON pitch reduction, we propose the introduction of optimal curvature poly-Si channels during Ls and Lg scaling.  
Through this study, we aim to provide important guidelines for improving the bit density in 3D NAND flash memory by analyzing the causes of changes in memory characteristics during ON pitch scaling and suggesting methods to enhance memory performance during the development of 3D NAND devices.
## 4 Results  
Application of Method for Short-Term Seedling Cultivation with VCs from Edible Mushroom FBs Resulted in Significant Biomass Increase  
To evaluate the growth effects of mushroom FBs-derived volatile compounds (VCs), rice seedlings were exposed to shiitake and enokitake FBs-derived VCs under controlled conditions, while control seedlings remained unexposed. After 14 days, plant height, root length, and biomass accumulation were measured.  
The results showed distinct effects of VCs emitted from shiitake and enokitake FBs on rice seedling growth and biomass accumulation (Figure 2). Seedlings exposed to shiitake FBs VCs exhibited significantly highest dry weight, 49.2 \(\pm\) 2.64 mg, representing a 67.4% increase compared to the control (29.4 \(\pm\) 1.20 mg) (Figure 2B). Enokitake-exposed seedlings also showed an increase in dry weight (41.0 \(\pm\) 5.59 mg), representing a 39.5% increase when compared with the control (Figure 2B). Similarly, plant height was significantly enhanced by shiitake VCs, whereby an average plant height of 40.4 \(\pm\) 1.16 cm, a 28.7% higher than the control (31.4 \(\pm\) 2.66 cm) was recorded (Figure 2C). Enokitake FBs VCs recorded a relatively lesser plant height of 34.9 \(\pm\) 7.33 cm, leading to only a 10.9% increase, which was statistically non-significant (Figure 2C). Root development was inhibited in rice seedlings exposed to both shiitake and enokitake FBs VCs when compared to controls. Seedlings exposed to shiitake FBs VCs had slightly longer roots than those exposed to enokitake, averaging 6.4 \(\pm\) 2.06 cm, a 30.4% reduction compared to the control (Figure 2D). A contrasting trend was observed in seedlings exposed to enokitake FBs which exhibited the most significant reduction in root length, averaging 5.0 \(\pm\) 0.63 cm, a 45.6% decrease compared to the control (9.2 \(\pm\) 1.83 cm) (Figure 2D). These results demonstrate that VCs from edible mushroom FBs are effective in promoting shoot growth and biomass accumulation. This suggests that the composition and activity of VCs may differ between FBs, influencing specific growth attributes in rice seedlings. In this study, shiitake FBs are shown to be a preferable source of VCs for plant growth and biomass promotion.
## 3 Methods
### Proportional Fairness Based Joint Antenna Selection and User Scheduling
Moreover, to cope with the rapid channel variation, more frequent channel estimations are required, which consume additional time-frequency resources due to the increased training overhead. It should be emphasized that the proposed JAS-OUS scheme remains applicable under such conditions, as it assumes that channel estimation has already been performed and that the base station has access to the necessary CSI, which forms the basis for communication. Based on this channel information, antenna and user optimization can be conducted. The estimation process itself is not the focus of this work; instead, we consider only the data transmission phase. Therefore, as long as the CSI is available, the proposed scheme can be executed. Of course, to ensure system reliability in practical deployments, it is essential to maintain accurate channel estimation throughout the communication process. Techniques such as shortened CSI update intervals and predictive channel estimation may be employed to track the channel in real time.
# Thrust Measurements on the High Efficient and Reliable Vacuum Arc Thruster (HERVAT)
## 2 Experimental Setup
### Thrust Balance Setup  
For the thrust measurements, a torsional thrust balance system from the FOTEK company and based on the system described in [14] has been chosen. This type of thrust measurement system has been used by other researches before and has proven its suitability for a pulsed vacuum arc thruster system [4; 8].  
Figure 4: Schematic top view (**top**) and photographic side view (**bottom**) of the thrust balance setup inside the vacuum facility. The detailed connections to the PPU are not shown.  
The thrust balance setup is composed of a central pivot rotating around a vertical axis and supporting a lever on which two tables are attached at each end, carrying the thruster and an equivalent counterweight (Figure 4, top). Upon the operation of the thruster, a rotational movement of the lever is induced. At the same time, a defined force is applied with an electrostatic actuator on the opposite end of the lever. If both applied forces are equal, the displacement of the lever, measured with an optical interferometric displacement sensor, vanishes. Thus, the force feedback gives the actual thrust value. This operational mode is also known as the compensation mode. The detectable thrust of this balance system ranges from 0.5 uN up to 5.5 mN with a resolution of 0.1 uN.  
For the electrical connection of the vacuum arc thruster to the PPU, torque- and force-decoupled wires are used. Decoupling is implemented with a liquid metal reservoir, as described in [4, 8].
# A Neural Network-Inspired Matrix Formulation of Chemical Kinetics for Acceleration on GPUs
###### Abstract  
High-fidelity simulations of turbulent flames are computationally expensive when using detailed chemical kinetics. For practical fuels and flow configurations, chemical kinetics can account for the vast majority of the computational time due to the highly non-linear nature of multi-step chemistry mechanisms and the inherent stiffness of combustion chemistry. While reducing this cost has been a key focus area in combustion modeling, the recent growth in graphics processing units (GPUs) that offer very fast arithmetic processing, combined with the development of highly optimized libraries for artificial neural networks used in machine learning, provides a unique pathway for acceleration. The goal of this paper is to recast Arrhenius kinetics as a neural network using matrix-based formulations. Unlike ANNs that rely on data, this formulation does not require training and exactly represents the chemistry mechanism. More specifically, connections between the exact matrix equations for kinetics and traditional artificial neural network layers are used to enable the usage of GPU-optimized linear algebra libraries without the need for modeling. Regarding GPU performance, speedup and saturation behaviors are assessed for several chemical mechanisms of varying complexity. The performance analysis is based on trends for absolute compute times and throughput for the various arithmetic operations encountered during the source term computation. The goals are ultimately to provide insights into how the source term calculations scale with the reaction mechanism complexity, which types of reactions benefit the GPU formulations most, and how to exploit the matrix-based formulations to provide optimal speedup for large mechanisms by using sparsity properties. Overall, the GPU performance for the species source term evaluations reveals many informative trends with regards to the effect of cell number on device saturation and speedup. Most importantly, it is shown that the matrix-based method enables highly efficient GPU performance across the board, achieving near-peak performance in saturated regimes.  
graphics processing units; high-performance computing; chemical kinetics; multi-physics simulation; neural networks; turbulent combustion +
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