esa-sceva/satcom-chunk-collection huggingface dataset:
# Large Thermal Expansion LTCC System for Cofiring with Integrated Functional Ceramics Layers
###### Abstract
Shrinkage mismatch between the LTCC- and functional material layers is supposed to be small in order to obtain dense multilayer ceramics without microstructural defects, e.g., warpage, delamination, or porosity [13]. Interdiffusion and extensive interface reactions should be avoided to preserve the correct performance of the embedded functional material layer. Constrained sintering, limiting the in-plane shrinkage and allowing tight dimensional tolerances, is a promising option for the fabrication of multilayer modules. Application of uniaxial stress supports the formation of dense multilayer samples, as shown for cofiring of Ni-Cu-Zn ferrites with LTCC tapes at 900 \({}^{\circ}\)C and 1-2 MPa [14]. Thermal expansion mismatch between LTCC- and functional layers is another potential source of error, causing thermomechanical stress and cracks. Therefore, matching of the coefficients of thermal expansion (CTEs) of the involved materials is required. The CTE of LTCC systems typically ranges from 4-7 ppm/K [1] and is tailored by compositional design [15]. However, functional ceramics, e.g., ferrites or perovskites often exhibit much larger CTEs in the range of 10-12 ppm/K. The design of LTCC systems with large CTEs is therefore needed for successful cofiring of functional and low-k LTCC layers. Few years ago, the design principles for LTCC glass ceramic composite systems with large CTE have been established [16]. In this paper we report on detailed investigations of the low-k LTCC system CT708 with large CTE developed by Heraeus [17]. The shrinkage and densification of CT708 multilayers is studied using different heating rates. Sintering at 900 \({}^{\circ}\)C results in high densities and a permittivity of \(\epsilon^{\prime}\) = 6.0 and a low loss tangent of tan \(\delta\) = 0.0004 (at 1 GHz). Multilayer samples of CT708 and a Sc-substituted hexagonal ferrite, needed as integrated microwave circulator components, were fabricated by cofiring at 900 \({}^{\circ}\)C. This demonstrates the possibility of cofiring of functional ceramics and low-k and large-CTE LTCC tapes and their potential for the fabrication of complex LTCC multilayer architectures.
## 3 Conceptual Model and Numerical Implementation
### Verification Process  
A comprehensive verification of the tool has been carried out; here, we present only three of the performed exercises. In Table 1, the parameters and initial and boundary conditions adopted in each exercise are shown.  
\begin{table}
\begin{tabular}{c c c} \hline \hline  & \multicolumn{3}{c}{**Qualification Exercises**} \\ \cline{2-3} Parameters & **Liquid Transport** & **Liquid and Vapor Transport** \\ \cline{2-3}  & **QE1 Analytic** & **QE2 Seep/W** & **QE3 HAMSTAD. Benchmark 2** \\ \hline \multicolumn{3}{c}{**Parameters and Dimensions**} \\ \hline \(L\) (m) & 0.01 & 0.01 & 0.20 \\ \(\phi\) & 0.3241 & 0.3241 & 0.1160 \\ Water retention function & \(Sr=b_{\text{s}}-a_{\text{s}}s\) & \(Sr=\left(1+(\alpha\,s)^{n}\right)^{-m}\) & \  
In the first two verification exercises (QE1 and QE2), a flux was imposed at the top of the domain, maintaining perfect drainage at the bottom. In the first case, a linear retention curve and constant hydraulic conductivity were assumed. These simplifications allowed the use of an analytical solution [28]. Figure 3a shows the satisfactory fit obtained with FLoW1D (with a mean absolute relative error (MARE) of 0.004%). For the second example presented, the same physical problem has been simulated, but the van Genuchten water retention curve and the non-constant hydraulic conductivity model defined in Table 1 were adopted. As a reference, this physical problem has been simulated using the well-known software SEEP/W-Geoslope(r)[29]. Figure 3b shows the good fit obtained (MARE = 0.22%).  
In addition to the liquid flow, the implementation of vapor transport has also been verified. Thus, among other exercises, benchmark 2[30] defined in the benchmark report generated in the international project HAMSTAD [31] (a project focused on the standardization of formulation of heat, air and moisture transfer models) has been simulated. This benchmark--named exercise QE3 in Table 1--studies the 1D isothermal water flow in a reference material caused by a sudden change of the environmental \(RH\). The results in Figure 4 show the good fit obtained (MARE = 1.77%), giving confidence regarding the use of FLoW1D to characterize the water transport in porous building materials.  
Figure 4: Water content isochrones (\(w\)) obtained with FLoW1D vs. reference solution (HAMSTAD Benchmark 2). Markers, reference solution; solid lines, FLoW1D results.  
Figure 3: Suction isochrones (s) obtained with FLoW1D vs. reference solution. (a) Analytic and (b) SEEP/W-Geoslope® Markers, reference solution; solid lines, FLoW1D results.
# Optimization on Linkage System for Vehicle Wipers by the Method of Differential Evolution
## 3 Results
### Comparison of the Linkage Lengths before DE Optimization with That after DE Optimization  
Our DE search results on the optimization problem of the objective function  
\[f(r_{3},r_{4},r_{5},r_{6})=\max_{0\leq\theta_{2}\leq 2\pi}|\alpha_{4}(r_{3},r_{4}, \theta_{2})|+\max_{0\leq\theta_{2}\leq 2\pi}|\alpha_{6}(r_{5},r_{6},\theta_{2})|\]  
of the maximal absolute values \(|\alpha_{4}|\) and \(|\alpha_{6}|\) of angular acceleration of the output-links of a commercially available CDLS are shown in Table 2.  
We notice that, on Figures 14 and 15, the _maximal absolute values_\(|\alpha_{4}|\) and \(|\alpha_{6}|\) of angular acceleration of the output-links respectively on the driver side and on the passenger side of CDLS become smaller after our DE optimization.  
\begin{table}
\begin{tabular}{c c c c c} \hline  & \(r_{3}\) (mm) & \(r_{4}\) (mm) & \(r_{5}\) (mm) & \(r_{6}\) (mm) \\ \hline Linkage length before DE & 209.0 & 66.8 & 206.0 & 69.9 \\ Linkage length after DE & 202.0 & 66.7 & 196.4 & 69.5 \\ \hline \end{tabular}
\end{table}
Table 2: Linkage lengths before/after DE optimization.  
Figure 12: Comparison of our modeling computation with that of ADAMS on \(\alpha_{5}\).  
Figure 13: Comparison of our modeling computation with that of ADAMS on \(\alpha_{6}\).  
We notice that, on Figures 18 and 19, both _transmission angles_ of CDLS become closer to \(\pi/2\)(rad) or \(90^{\circ}\) after our DE optimization. In fact, this optimization slightly improves the effective torques of the output links of CDLS. See Table 3.  
Figure 19: The transmission angle \(\mu_{6}\) of the passenger side output-link of CDLS before/after DE optimization.  
Figure 17: The angular velocity \(\omega_{6}\) of the driver side output-link of CDLS before/after DE optimization.  
Figure 18: The transmission angle \(\mu_{4}\) of the driver side output-link of CDLS before/after DE optimization.  
The resulting reduction of deviation of transmission angles from \(\pi/2\) clearly shows us that the torque-efficiency by the input-link is improved. Thus improvement on the _steadiness_ of a linkage system for vehicle wipers could also reduce the possible material fatigue of a linkage system.  
Notice that, on Table 4, our optimization reduces the maximal magnitude max \(|\alpha_{4}|\) of angular acceleration of the output-link on the driver side of CDLS by 10.69%. Besides, notice that, on Table 5, our optimization reduces the maximal magnitude max \(|\alpha_{6}|\) of angular acceleration of the output-link on the passenger side of CDLS by 12.10%.
# Retrospective Spectrum-Conversion Method Based on Time-Modulated Van Atta Array
## 3 Van Atta Array Design
### The Design of Antenna  
As a Van Atta array antenna, the series-fed array antenna has unique advantages over other antenna array connections due to its light weight, compact size, and simple feeding. To maximize the overall array efficiency and achieve high gain, a series resonant rectangular microstrip patch array is used as the antenna for the Van Atta array, as shown in Figure 2.  
The designed Van Atta array consists of eight columns of resonant series-fed rectangular microstrip patch arrays. Eight patch antennas are symmetrically distributed at equal intervals in each column. The interval between two adjacent patches is the wavelength \(\lambda_{\mathrm{g}}\) to weaken the mutual coupling of adjacent elements. The width of the patch antenna element decreases sequentially from the center to both ends to reduce side lobes.  
From the perspective of equivalent circuits, a series array is a combination of parallel resonant circuits, with each resonant circuit representing a single surface mount component. Due to the fact that adjacent patches are spaced apart by a resonant wavelength, their reactances cancel each other out, leaving a parallel combination of input resistors. Using CST 2022.4 simulation, the characteristics of the designed antenna are shown in Figure 3.  
The reflection coefficient of the designed resonant series patch array is shown in Figure 4a, which is less than \(-10\) dB in the frequency band of 3.45-3.55 GHz. The gain of the antenna is 14.2 dBi at 3.5 GHz. As shown in Figure 4b, on the E-plane of the antenna,  
Figure 1: The phase conjugation principle of planar Van Atta array.  
Figure 2: The designed series-fed array antenna.  
the antenna gain should be maximized to maintain the required backward reflectivity. By adjusting the width of the rectangular patch, the sidelobes are reduced to 15 dB smaller than the main lobe. On the H-plane, in order to ensure a large RCS of the Van Atta array under oblique incidence, it is necessary to ensure relatively consistent gain over a large angle range on the H-plane, which is also a unique feature of the Van Atta array antenna.
# Jam Mitigation for Autonomous Convoys via Behavior-Based Robotics
## 2 Background  
The purpose of this effort is to develop an autonomous ground vehicle convoy system that mitigates the effects of jamming by utilizing a behavior-based robotics approach. To enable proper exploration of the effort, the following sections provide a brief background on three topics fundamental to our work: autonomous ground vehicle convoys, jammers, and behavior-based robotics.
# Leveraging Retrieval-Augmented Generation for Swahili Language Conversation Systems
## 4 Experimentation
### Experimental Results
#### 4.3.4 ROUGE-L Score Analysis  
The graph in Figure 12 presents a comparison of ROUGE-L scores for four different models: mT5, mBART, GPT-2, and GPT-Neo. The scores are shown under two conditions: fine-tuned and Retrieval-Augmented Generation (RAG). ROUGE-L is a widely used metric to evaluate the performance of text generation tasks by comparing the generated text to reference text. A higher ROUGE-L score signifies greater similarity, indicating better performance. As observed from the figure, the RAG models outperformed the fine-tuned models in all four models tested. Notably, mT5, GPT-2, and GPT-Neo showed significant improvements in their ROUGE-L scores when integrated with the RAG framework. This improvement suggests that the addition of retrieval-based information, which enhances the generation process, leads to more accurate and contextually relevant outputs. mT5 exhibited the most pronounced improvement, with the highest ROUGE-L score in the RAG condition, while GPT-2 and GPT-Neo also benefited notably from the retrieval mechanism [56]. These improvements indicate that the RAG framework helped boost the performance of these models by leveraging external information to generate more fluent and relevant responses. On the other hand, mBART shows a relatively smaller improvement under the RAG condition. This could be due to its initial performance, which already aligns closer to the RAG-enhanced results, suggesting that the impact of RAG might vary depending on the model's baseline performance. The graph clearly demonstrates that RAG provides a clear advantage in enhancing the performance of language models for Swahili NLP tasks. By enabling the retrieval of additional information, RAG helps models produce more accurate and contextually grounded responses, especially in low-resource settings where data may be limited.  
Figure 11: METEOR score comparison between Fine-Tune and RAG models.
## 3 Case Study  
The presented numerical analysis aims at investigating the application of an innovative POCS structure as a pre-catalyst in the after-treatment system of a gasoline spark ignition ICE. It is meant to be located upstream of a conventional catalyst, in particular, in the initial portion of each exhaust manifold. At first, the geometrical details of the preliminary design of the POCS structure are presented. In addition, the geometry is modified to be compliant with the characteristic shape of a selected exhaust manifold. The induced pressure drop is analyzed for both configurations as a function of different flow velocities. The obtained data are employed to estimate an equivalent friction factor and to perform the 1D simulation of a reference ICE; as such, the impact of the considered POCS application on the engine performances can be assessed. Finally, the effects related to Joule heating are investigated; after a sensitivity analysis on the applied potential difference, the selected operating conditions are employed to simulate the thermal transient of the complete exhaust line for simplified cold start conditions. The obtained results are compared to the reference case, consisting of the same geometry excluding the equipment of the POCS structures.  
The computational grids employed for the present work were generated using a Cartesian mesh generator in the OpenFOAM environment. The resulting mesh is predominantly hexahedral with a small percentage of polyhedral elements near the boundary walls. The advanced grid generator includes automatic meshing features for the addition of boundary layers. In the case of turbulent simulations, for a progressive description of the centerline of the cells and an accurate reconstruction of the fluid fields gradients, computational meshes with structured O-grids along the walls were employed.
# PLORC: A Pipelined Lossless Reference-Free Compression Architecture for FASTQ Files
## 4 Results and Discussion
### Compression Ratios  
As illustrated in Table 8 and Figure 21, our PLORC compressor achieved a better compression ratio than Gzip, LZ4, and Zstd.  
Our compression algorithm was specially designed and implemented according to the structure of FASTQ files. Therefore, the PLORC compressor can better reduce contextual redundancy.  
Gzip, LZ4, and Zstd utilize a sliding window and dictionary-based methods to reduce contextual redundancy. When applied to FASTQ files, the size of one read often exceeds the size of the sliding window. Therefore, general compression algorithms, such as Gzip, LZ4, and Zstd, often fail to capture much contextual redundancy.  
The reference-based design in [16] achieved a superior CR 14.1 on a 964 MB FASTQ file from the ERP001652 dataset [53]. However, this high CR depends on manual selection for reference. Additionally, it consumes a great deal of hardware resources, as illustrated later in Section 4.5.
# Shapley's Value as a Resource Optimization Strategy for Digital Radio Transmission over IBOC FM
## 2 Materials and Methods
### Digital Radio on IBOC  
Radio serves as a public service with a profound impact on the social development of a country's inhabitants, aiming to ensure the right to information, recreation, free expression, and personal growth. To harness the benefits of digitalization, countries worldwide have initiated efforts to accelerate digital terrestrial migration by formulating national plans to establish digital broadcasting infrastructure and phase out analog services. Leading countries such as Norway, Denmark, Switzerland, the USA, and Japan have spearheaded various radio standards as needed, with some announcing digital transition dates. Progress in this transition has been steady, with countries like Germany and the Netherlands embracing digital technology, while others like Spain, Sweden, and Ireland adopting a wait-and-see approach. Successful implementations of digital radio standards have occurred in the US and Japan. One of the significant challenges in choosing a digital radio standard is making the right decision considering all technical aspects to meet each country's needs and demands [17].  
Currently, digital radio penetration worldwide is predominant in North America, where the IBOC system is chosen, and in Europe, where the DAB standard is adopted. Latin America lacks a precedent, but countries like Argentina and Chile have shown interest in radio digitalization [18]. Consequently, numerous countries are in the implementation process or interested in transitioning from analog to digital broadcasting. It is crucial to understand the characteristics of these technologies to select the most suitable one based on existing broadcasting conditions, user needs, and country regulations.  
In most countries, implementing a digital broadcasting system requires resolving technical and regulatory aspects. Firstly, regarding frequencies for the chosen digital broadcasting system, determining working frequencies is necessary to enable the simultaneous use of analog and digital receivers. This situation favors IBOC technology over others such as DAB, which necessitates a broader scale change [19]. Secondly, in the regulatory domain, mechanisms for frequency allocation, license granting, and participation of new stakeholders need to be defined. Given the experiences in the United States and recommendations from the FCC, IBOC may be the likely technology for digital broadcasting implementation in countries like Colombia. Hence, a detailed description of the communication protocols within this standard for audio coding and transmission in a digital context is presented below.
## 3 Results and Discussion
### Prediction Accuracy of CB Model  
The regression error characteristic (REC) curve is a visualizing tool used for evaluating the performance of regression models. The REC curve provides a comprehensive visualization of predictive accuracy by plotting the error tolerance (absolute deviation) on the \(x\)-axis against the model accuracy (fraction of predictions within that tolerance) on the \(y\)-axis. The area under the curve (AUC) provides a measure of overall performance. A larger AUC generally indicates better performance, as it means the model can achieve higher accuracy. The area over the curve (AOC) is considered a biased estimation of the expected error, which can be calculated as (AOC = \(1-\) AUC) [91]. Figure 10 illustrates the REC curves of the developed models in the testing phase. Obviously, the CB model secured the top performance rank by achieving the highest accuracy (AUC = 0.931) and the lowest error (AOC = 0.069). The CB model was also evaluated against ML models previously developed in the literature, as demonstrated in Table 5. Again, the CB model developed in this research outperformed all existing models in predicting the SS of RCDBs by achieving the highest prediction accuracy.
## 3 Results and Discussion
### Influence of NaCl Concentration on Binding Properties  
The presence of NaCl in the adsorption solution could affect the adsorption ability of imprinted materials, mainly when the anion exchange mechanism is involved [24]. As shown in Figure 6, the binding capacity and imprinting factor of the PVC@TAA-MIP toward BSA gradually decreased with the increasing NaCl concentration. This observation was mainly attributed to the competition of chloride ions with the template through the anion exchange reversible reaction [45]. However, the binding capacity of PVC@TAA-NIP toward BSA showed no significant change as a function of the NaCl concentration. This revealed that the surface of the non-imprinted material lacked electrostatic interaction from residual charged moieties, because they were entirely covered after SI-PIMP. These results suggested that the non-specific binding of the template decreased significantly when using the combination of the immobilization template and surface-initiated polymerization technique. Compared to previous studies that utilized randomly oriented charged monomers to synthesize imprinted materials based on the anion exchange mechanism, the polymers reported in this study demonstrated a superior imprinting factor.  
Figure 5: Influence of irradiation time on imprinted PVC@TAA-MIP film thickness.
# Influence of Different Base Materials on the Microstructure and Properties of Clad Rebar
## 3 Results and Discussions  
### Uniformity Analysis of Clad Layer Thickness  
Figure 5 shows the sizes of the end surfaces in the rebars. For all four types of rebars, the minimum cladding thickness occurred at the roots of the transverse ribs due to the existence of a sharp region at the K1 crescent groove, which obstructed the movement of the stainless steel along the groove. During the simulation of finish rolling on the clad rebar, [PERSON] et al. discovered a similar pattern [19]. The minimum cladding thickness decreases in the order 20 MnSiV/316L (0.35 mm) \(>\) 55#/316L rebar (0.26 mm) \(>\) 45#/316L rebar (0.22 mm) \(>\) 35#/316L rebar (0.11 mm).  
Moreover, Figure 5 shows that the distance between the two longitudinal ribs in the 20 MnSiV/316L rebar was 33.1 mm, while that in the 35#/316L rebar was 31.88 mm. This indicates that the deformation in the clad rebar along the lateral spread increases with increasing strength of the base material.  
Table 3 shows the average, range, and variance for the cladding thickness of various rebars. Table 3 suggests that both the range and variance of the 20 MnSiV/316L rebar cladding thickness are the smallest, which are 1.34 and 0.11 mm, respectively. By contrast, 35#/316L has the largest range and variance of cladding thickness, which are 1.6 and 0.17 mm, respectively.  
Figure 6 shows the stress-strain curves of the base and clad layers. Compared to 35#, 45#, and 55# carbon steel, 20 MnSiV exhibits a stress-strain curve that is closer to the stress-strain curve of 316L stainless steel. This indicates that 20 MnSiV and 316L stainless steel have similar deformation trends under the same load. Therefore, the cladding thickness of 20 MnSiV/316L rebar was more uniform than in the other three types of rebars. Table 3 also suggests that there is little variation in the average cladding thickness of rebars, which fluctuates between 0.98-1.04 mm. Consequently, the cladding thickness of rebars is not related to the base material.  
Figure 5: Surface sizes of the ends of various rebars: (**a**) 20 MnSiV/316L rebar; (**b**) 35#/316L rebar; (**c**) 45#/316L rebar; (**d**) 55#/316L rebar.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Rebar Type** & **Average (mm)** & **Range (mm)** & **Variance (mm)** \\ \hline
20 MnSiV/316L & 1.04 & 1.34 & 0.11 \\
35\#/316L & 0.98 & 1.6 & 0.17 \\
45\#/316L & 1.02 & 1.48 & 0.14 \\
55\#/316L & 0.95 & 1.46 & 0.13 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Average, range, and variance for various rebars.