esa-sceva/satcom-chunk-collection huggingface dataset:
# Analysis of Optimal Loading Angle in Dynamic Flattened Brazilian Disc Splitting Test for Concrete
## 1 Introduction
[32; 33] found that if the loading angle was too large, the failure of the specimen tended to deviate from the symmetry plane. Based on cusp catastrophe theory, he suggested that the loading angle should be no larger than 30\({}^{\circ}\). [PERSON] et al. [34] proposed two loading modes for the flattened BD tests: (1) uniformly distributed loads directly act on the specimen and (2) loads indirectly act on the specimen through a cushion block. It was concluded that the loading angle must be no less than 20\({}^{\circ}\) for the first loading mode, while in the second loading mode, the loading angle must be no less than 15\({}^{\circ}\). The recommended loading angles are basically between 15\({}^{\circ}\) and 30\({}^{\circ}\) for rock materials tests, while little research was reported on concrete materials. Whether those conclusions obtained from rocks can be extended to concrete at a high loading rate remains unknown. The purpose of this study is to explore the influence of the loading angle on the failure of self-compacting concrete (SCC) and subsequently determine the optimal range of the loading angle to measure the tensile strength of SCC in the flattened BD test under dynamic load. Initially, the numerical simulation of the traditional Brazilian disc was carried out to study the mechanism of crack propagation. Secondly, the theoretical analysis of the platform Brazilian disc was carried out to study the influence of different loading angles on the stress field. Finally, the flattened Brazilian splitting experiment was implemented with a split Hopkinson pressure bar (SHPB). The crack initiation and failure process were detected by both digital image correlation (DIC) and strain gage. The relationship between loading angle and dynamic tensile strength of SCC was obtained.
# An Iterative Optimization Algorithm for Planning Spacecraft Pathways Through Asteroids
## 7 Conclusions  
In this study, we experimentally investigated the performance of FAT-RLS, a straightforward trajectory-based meta-heuristic, in addressing the Asteroid Routing Problem (ARP). FAT-RLS utilizes a well-established randomized local search approach and is enhanced by two additional components: a tabu data structure and a mechanism for adaptive perturbation strength.  
We carried out a series of experiments using standard benchmark instances for the ARP to compare the performance of FAT-RLS against two established methods: CEGO, a Bayesian approach designed for combinatorial issues; and UMM, an estimation-of-distribution algorithm specifically created for permutation problems. The experiments were performed in two different contexts: an uninformed setting, where the initial solutions for the competing algorithms were generated randomly; and an informed setting, where a specifically defined heuristic method was employed to initialize the solutions for the competing meta-heuristics.  
The results demonstrate that FAT-RLS, despite its straightforward design, surpasses both CEGO and UMM in the uninformed scenario, where the ARP is approached without prior knowledge. However, in the context of heuristic initialization, FAT-RLS significantly outperforms UMM, but there is no conclusive evidence indicating its superiority over CEGO.  
Consequently, these findings reinforce the key message previously highlighted in [21]: simple algorithms like FAT-RLS, which primarily rely on robust exploitation strategies, can serve as a viable alternative to more complex techniques in low-budget and high-cost black-box combinatorial scenarios.  
Moreover, the results examined, particularly those from the smaller instances, indicate that FAT-RLS lacks robustness in certain situations, highlighting potential areas for improvement. Thus, a direction for future research would be to change the algorithm search mechanism from the randomized local search framework to the \((1+1)\)-EA scheme [47]. The core concept is to keep the expected number of insertion moves per iteration at one, while permitting the algorithm to execute multiple insertions within a single iteration. This strategy seeks to maintain a strong level of exploitation while minimizing the chances of the algorithm becoming stuck in a local optimum within the insertion neighborhood. Finally, another interesting future avenue of research is to approach other trajectory optimization problems in the field of space engineering [11; 12; 13; 14].  
This research has been partially supported by the research project \"Universita per Stranieri di Perugia-Finanziamento Dipartimentale alla Ricerca per Progetti di Ricerca di Ateneo-FDR 2024\".  
The original contributions presented in the study are included in the article, further inquiries can be directed to the corresponding author.  
The author declares no conflicts of interest.
###### Abstract  
Pulsed Coherent Doppler Wind Lidar (CDWL) usually utilizes a fixed-length range gate to divide the time domain of the echo signal, which can lead to the incomplete sampling of echo signals, resulting in a spectral leakage phenomenon and affecting the wind speed inversion accuracy. In this paper, we propose to utilize the Hanning Self-Convolutional Window (HSCW) to preprocess the wind speed echo signal, suppress the spectral leakage phenomenon, and improve the wind speed inversion accuracy of the algorithm. Simulation experiments show that the signal-to-noise ratio (SNR) is 3.28 dB higher than that of the Rectangular Window (RW), and the average root mean square error (RMSE) values of the first- to third-order HSCW are 164.2 kHz, 116.7 kHz, and 101.9 kHz, respectively. The comparison of wind speed with a commercial CDWL shows that the RMSE of the second-order HSCW inversion result is 0.184 m/s, while the RW and first-order HSCW are 0.449 m/s and 0.266 m/s, respectively.  
window function; spectral leakage; echo signal processing +
Footnote †: journal: applied sciences
## 3 Results
### Models for Relationship between Yield Parameters and VIs
Figure 5: Scatter plot between those VIs identified to have the highest coefficient of determination to total fruit weight (kg\(\cdot\)tree\({}^{-1}\)) for each sampled block derived from WorldView-2 (WV2) and WV3 imagery. The 2014 sample points are presented as a triangle (\(\Delta\)) (n = 9 per block) in blocks 1 and 2, with 2016 as a diamond (\(\Diamond\)) (n = 18 per block) and 2017 as circle (o) (n = 18 per block). The results of stepwise regression and ANCOVA for average fruit size (g) per tree in all five blocks are shown in Table 3. No significant differences were observed in slopes for any of the three years data for all five blocks, with the lowest \(p\)-value = 0.07 for Block 2. However, the intercepts again differed for all blocks except block 5 (\(F\)-value = 0.67 and \(p\)-value = 0.42). This results show the consistency of correlation between average fruit size (g) per tree data against optimal VI in different years. \begin{table}
\begin{tabular}{c c c c c} \hline \multirow{2}{*}{**Blocks**} & \multicolumn{2}{c}{**Slopes**} & \multicolumn{2}{c}{**Intercepts**} \\ \cline{2-5}  & \(F\)**-Value** & \(p\)**-Value** & \(F\)**-Value** & \(p\)**-Value** \\ \hline Block 1 & 0.72 & 0.49 & 16 & 0 \\ Block 2 & 2.85 & 0.07 & 11.6 & 0.0001 \\ Block 3 & 0.23 & 0.63 & 4.72 & 0.04 \\ Block 4 & 0.23 & 0.63 & 3.98 & 0.05 \\ Block 5 & 2.87 & 0.10 & 0.67 & 0.42 \\ \hline \end{tabular}
\end{table} 
Table 3: The stepwise regression and Analysis of covariance (ANCOVA) results for average fruit size (g) per tree for Block 1 and 2 in three years period and Block 3, 4, and 5 in two years period. Figure 6: Scatter plot between those VIs identified to have the highest coefficient of determination to average fruit weight per tree (g) for each sampled block derived from WV2 and WV3 imagery. The 2014 sample points are presented as a triangle (\(\Delta\)) (n = 9 per block) in blocks 1 and 2, with 2016 as a diamond (\(\lozenge\)) (n = 18 per block) and 2017 as circle (o) (n = 18 per block).
###### Abstract  
This paper reports the implementation of two critical technologies used in light detection and ranging for space applications: (1) a microchip Q-switched laser breadboard; (2) a breadboard of an indium gallium arsenide avalanche photodiode working at 292 K with high reverse polarization voltages. Microchip Q-switched lasers are small solid-state back-pumped lasers that can generate high-energy short pulses. The implemented breadboard used an erbium and yytterbium co-doped phosphate glass, a Co-Spinel crystal with 98% initial transparency, and an output coupler with 98% reflectivity. For the sensor test, a system for simultaneous operation in vacuum and a wide range of temperatures was developed. Avalanche photodiodes are reverse-polarized photodiodes with high internal gain due to their multiple layer composition, capable of building up high values of photocurrent from small optical signals by exploiting the avalanche breakdown effects. The test avalanche photodetector was assembled to be operated in two modes: linear and Geiger mode. The produced photocurrent was measured by using: (1) a passive quenching circuit; (2) a transimpedance amplifier circuit. These two technologies are important for mobile light detection and ranging applications due to their low mass and high efficiencies. The paper describes the breadboard's implementation methods and sensor characterization at low and room temperatures with high bias voltages (beyond breakdown voltage).  
spacecraft; LiDAR; microchip laser; SPAD; APD; Geiger mode; asteroid; new payloads; space missions +
Footnote †: journal: Applied  
Accepted: 1 May 2023  
Published: 3 May 2023
## 3 Results and Discussion
### Cenospheres Recovery Yield
Both mechanical stirring and ultrasonicating by applying sound energy to agitate particles in liquid revealed the similar result (Figure 1f), clearly indicating that the separation of cenospheres is independent on the physical mixing process. Similarly, size sieving aimed to deagglomerate particles prior to the sink-float separation did not show the improved cenospheres yield. One may assume that the cenospheres yield is limited by the stirring-settling effect associated with the cenospheres content by nature. In Figure 1e, the tendency of cenospheres yield for the large particle fractions is comparatively lower than that of the yield for the smaller particle fractions. This is attributed to the porosity and rough surface texture of the particle significantly influencing the movement and velocity of particles in the fluid [18; 44]. However, it should be noted here that the fly ash-medium ratio of 1:10 is the optimal acquisition condition found widely used for cenospheres separation via the sink-float method [18; 28]. A comparison of the cenospheres yield obtained from different experiments is shown in Table 3. As the ash particles experienced the gravity separation, there could possibly be some broken cenospheres that become heavier and sink along with the small fly ash particles. Using water as a medium, it was possible to obtain cenospheres fraction composed of intact (undamaged) spheres by 2/3 of volume and a sediment part by 1/3 of volume consisting of small ash particles, cracked or fissured cenosphere ash particles, semi-coked particles, cooked particles, slag fragments, and magnetic microspheres [18; 37]. These were drawbacks of the gravity separation, that the cenosphere separation efficiency can be influenced by the fragments of various materials, broken spheres, and fine fly ash contaminated. Further, the fine fly ash particles could also form dense accumulation on the floating surface that in turn limits their sinking and eventually resulting in an increase in impurity of the cenosphere product, with such phenomenon possibly found for the separation of class C and class F fly ash [18]. The dense, fine fly ash particles found mixing with the collected cenospheres can be seen in this study (see the XRF imaging result). One may also be possible for the impurity inclusion is that the crushed but remaining unsinkable cenospheres could be found with the collected cenosphere fractions.
# A Novel Reconfigurable Vector-Processed Interleaving Algorithm for a DVB-RCS2 Turbo Encoder
## 5 Portability and Architectural Considerations  
The proposed algorithm, while currently implemented and optimized for the CEVA-XC4500 DSP, is designed with portability in mind. Its structure and computational logic are not inherently tied to any CEVA-specific hardware features. Rather, the algorithm is built upon a general Load-Execute-Store (LES) model, which is applicable across a wide range of parallel and vector processing architectures.
## 4 Methodologies and Results Analysis
### Primary Phase
The proposed system could also capture a group of faces captured in a single frame using modified Haar cascade crowd classifiers, as presented in Figure 9. Figure 9 represents non-human object samples which were not captured by the smart home anti-theft system during the conducted experiments. To conduct non-human object detection experiments, samples of dogs, cats, sparrows, and parrots were used as described in Figure 9. \begin{table}
\begin{tabular}{c c} \hline \hline
**Types of Face Detection** & **Face Detection Rate Accuracy in an Ordinary Scenario (\%)** \\
**Methodologies** & **[Total Sample Size = 5000]** \\ \hline Modified Haar Cascade & 97.01 \\ Neural Networks & 75.4 \\ Skin Segmentation Template & 52.3 \\ Matching Modified Haar Cascade & 65.87 \\ Higher Order Statistics & 72 \\ Two Step R-CNN Method & 94 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Face Detection Rate Accuracy Analysis of the modified Haar Cascade Classifier with existing methodologies in a scenario, where an intruder has not occluded their face. Figure 7: Haar cascade image classifier samples (all of the shown human faces in the conducted experiments required copyright permission obtained on 19 March 2017). As shown in Figure 10a, rigorous research experiments were conducted with approximately 10,000 diverse samples in scenarios where an intruder was detected in ordinary scenarios and where an intruder had not fully/partially covered his/her face. The ratio of accurate face detection was 100% in more than 97% of cases for more than 10,000 face samples. Figure 10b depicts the face detection rate analysis of 97% accuracy cases in the form of heat map representation. Figure 8: Schematic representation of cascade classifiers. Figure 10: _Cont._  
Figure 9: (a) Crowd Cascade Image Classifier Sample (copyright permission for photograph obtained on 1 April 2017). (b) Non-human objects samples (copyright permission for photograph obtained on 9 July 2017).
# Concrete Silos: Failures, Design Issues and Repair/Strengthening Methods
## 4 Repair and Strengthening Methods for Reinforced Concrete Silos
### Durability Improvement and Corrosion Protection  
The durability of RC structures can be enhanced by mitigating the risk of corrosion of the steel reinforcements. The protection of the structure against corrosion can be achieved by controlling moisture accumulation and relative humidity in the bulk solids through aeration [84] using dehumidifiers. The degradation of bulk grains due to microbial activity and the presence of corrosion-inducing bacteria should be monitored, and liners and sacrificial plates should be installed to limit the abrasion of the inner walls of the silo by coarse grains. The risk of corrosion can be reduced further by corrosion inhibitors such as sodium mono-fluoro-phosphate (MFP), calcium nitrites (CN), and amino alcohols (AMAs) [85], whose mechanism of inhibition involves competitive surface adsorption and migration of ions and pH buffering. Alternatively, infusing silica fumes into the steel rods during the production phase has been proven to offer protective benefits compared to steel rods, without silica fumes [86]. The RC repair standards including EN1504 and European Standard EN 13670:2009, suggest that the repair of concrete should be based on the identification of products and methods, specifications, and quality parameters [87]. Additionally, the standards assume that designers and engineers bear responsibility for all aspect of construction, useful lite/utilization and repair. Such assumptions might not apply in real applications.
###### Abstract  
Introduction: This study aimed to evaluate the validity of the HandyGym portable flywheel device with an integrated rotary encoder in measuring force and power during iso-inertial exercises compared to a traditional reference system. Methods: In total, 10 trained volunteers (3 women, 7 men; age 25.2 \(\pm\) 3.8 years) performed half-squats with five different load configurations using the HandyGym device. Concurrent measurements were obtained from HandyGym's rotary encoder and a criterion system (MuscleLab 6000 strain gauge and linear encoder). Five load configurations were tested, with 15 repetitions recorded per condition. The validity of the HandyGym measurements was assessed through mean bias, typical error of estimation (TEE), and Pearson correlation coefficients, with Bland-Altman plots used to analyze the agreement between the two systems. Results: The HandyGym showed high correlations with the reference system for both force (r = 0.76-0.90) and power (r = 0.60-0.94). However, systematic biases were observed, with the HandyGym consistently underestimating force and power at lower loads and overestimating power at higher loads. The TEE values indicated moderate to large errors, particularly in power measurements. Conclusion: The HandyGym provides valid force measurements with moderate bias, suitable for general monitoring. However, power measurements are less consistent, especially at higher loads, limiting the device's utility for precise assessments. Adjustments or corrections may be necessary for accurate application in professional contexts.  
isomertial training; strength training; sports technology; training load; monitoring
# Attention-Based Color Difference Perception for Photographic Images
## 4 Experiment
### Main Results
To verify the generalization of the proposed CD-Attention model, the TID2013 dataset is used to train the model. The TID2013 dataset is used for image quality assessment and contains 25 reference images and 3000 distorted images. These distorted images are generated through 24 different distortion types, with 5 distortion levels for each type. Mean Opinion Score (MOS) values are obtained from 971 experimental observers from five countries. Distortion types related to CD in the dataset are selected for model training. The results are evaluated using STRESS, PLCC, and SROCC metrics, as shown in Table 2. According to the data in the table, although CIEDE2000 [6] is considered the best-performing CD formula in predicting experimental datasets currently, its performance is mediocre. Compared with the existing image quality assessment methods PieAPP [21], LPIPS [22], and DISTS [23], the performance of CD-Attention has improved, proving its better generalization performance. When compared with the current best algorithms CD-Net [28] and CD-Flow [29], a higher correlation is shown by CD-Attention, demonstrating its superior generalization performance.
## 3 Microfabrication of Suspensions of Fibers by Colloidal Self-Assembly
### Principle of Fabrication  
The fabrication technique relies on the self-assembly property of superparamagnetic colloids and magneto-stimulated bridging between them. A microfluidic channel filled with a solution of such colloids is placed on the stage of a microscope equipped with a coil to produce a vertical magnetic field. When the magnetic field is applied, each colloidal particle acquires a magnetic moment parallel to the magnetic field \(\mathbf{B}\), along the height of the channel. Dipolar interactions are attractive in a solid angle along the direction of the field and with an apex of \(55^{\circ}\). They induce self-assembly  
Figure 4: Adapted from [13] with permission from the Royal Society of Chemistry, 2015. (**a**) Successive positions of deformed fiber; (**b**) measured fiber deformation with respect to the flow velocity; (**c**) results of [PERSON]’s moduli for different exposure times. A movie showing the fiber deforming under flow is available in Supplementary Materials Video S2.  
of one-dimensional structures aligned with **B**. Since the particles are superparamagnetic, once the magnetic field is removed, the colloids move freely and independently in the solution due to Brownian motion. To form permanent filaments, we add polymer to the colloidal suspension. The polymers adsorbed on the surface of each particle will also adsorb to the neighboring particles in the chain (as illustrated in Figure 5) if the surfaces remain close enough during long enough time [17]. There is thus a threshold in the magnitude of the magnetic field above which permanent bridging is achieved and below which the chain will disassemble when the magnetic field is switched off. This threshold is essential to obtain a controlled one-dimensional structure. If particles were simply adhesive, the many collisions that they experience due to their Brownian motion would lead to random aggregation.
# Modelling, Analysis and Performance of a Low Inertia AC-DC Microgrid
## 3 Stability Analysis
### Impact of Generator Inertia Variation  
Figure 8 shows the dominant poles with the changing in the generator inertia from 0.8 to 1.5 of the nominal value. The poles moved towards the left and produced a more stable response as the synchronous generator inertia is the only source of traditional inertia in the proposed microgrid system.