esa-sceva/satcom-chunk-collection huggingface dataset:
# Scalable Block Preconditioners for Linearized Navier-Stokes Equations at High Reynolds Number
## 7 Numerical Results
### Multigrid and BFBt
#### 7.4.1 Jacobi/BFBt  
The first combination involves a damped Jacobi smoother; the Multigrid used is \(5V(1,1)\), while the BFBt preconditioner is implemented using an incomplete factorization.  
Table 2 reports the spectral properties of the preconditioned matrices.  
The eigenvalues of the preconditioned \((1,1)\) block show a slight dependence on the mesh size (\(\alpha_{F}\) is decreasing, \(\beta_{F}\) is increasing), even for the highest viscosity, which represents a problem that is similar to the Stokes one. The smallest eigenvalue \(\alpha_{F}\) does not seem to be affected by the value of the viscosity, while the biggest one \(\beta_{F}\) grows substantially with the viscosity, getting in the worst case to a value larger than 5. The fact that the spectral properties deteriorate as the viscosity grows is perfectly in line with the fact that this Multigrid preconditioner was built for a symmetric problem, while lowering the viscosity makes the problem increasingly asymmetric. For an even lower viscosity (0.005), the eigenvalues become negative, leading to a complete failure of the preconditioner.  
The situation is not better for the Schur complement preconditioner: even in this case, the spectral interval widens as the mesh is refined. Moreover, the eigenvalues are less clustered around 1, as the spectral radius is always above 20.  
Figure 6 illustrates the spectrum of the preconditioned Schur complement for various values of the viscosity. Every dot represents an eigenvalue in the complex plane (only the first 100 eigenvalues found by [PERSON] are represented). These spectra do not depend on the Multigrid scheme used, so they would be the same as even using a different Multigrid. It is clear that, as the viscosity gets lower, the system becomes more asymmetric and, consequently, the imaginary part of the eigenvalues increases.  
Table 3 shows the results obtained with [PERSON] and BFB: even with very high viscosity, the preconditioner is not scalable; for low viscosity instead, it fails completely.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Matrix** & **Viscosity** & \(\alpha_{F}\) & \(\beta_{F}\) & \(\alpha_{S}\) & \(\beta_{S}\) \\ \hline \multirow{2}{*}{M40} & 0.1 & 0.4256 & 1.261 & 0.6926 & 25.86 \\  & 0.01 & 0.4251 & 1.905 & 0.4746 & 21.87 \\ \hline \multirow{2}{*}{M80} & 0.1 & 0.3555 & 1.442 & 0.2107 & 26.62 \\  & 0.01 & 0.3588 & 2.911 & 0.1494 & 25.92 \\ \hline \multirow{2}{*}{M160} & 0.1 & 0.3371 & 1.700 & 0.0557 & 39.41 \\  & 0.01 & 0.3383 & 5.013 & 0.1744 & 28.97 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Spectral properties of the preconditioned matrices using [PERSON] and BFBt.  
Figure 6: Spectra of the BFBt-preconditioned Schur complement for different values of viscosity. (**a**) \(\
u=0.1\); (**b**) \(\
u=0.01\); (**c**) \(\
u=0.005\).
# Experimental and CFD Simulation Studies on Bell-Type Air Nozzles of CFB Boilers
## 5 Conclusions  
The new bell-type air nozzle scheme is designed to overcome the inherent defects of traditional bell-type air nozzles. Through the cold-state experiment and numerical simulation, the pressure drop characteristics of the new bell-type air nozzle were determined. The following research conclusions were obtained.  
1. For the bell-type air nozzle, results of the numerical simulation agree with those of the cold-state experiment.  
Figure 14: Inner tube orifices outlet velocity vector of nozzle A and nozzle B. (**a**) nozzle A (100% load); (**b**) nozzle B (100% load); (**c**) nozzle A (30% load); (**d**) nozzle B (30% load).  
Figure 15: Air nozzle arrangement before and after transformation. (**a**) before transformation (nozzle A); (**b**) after transformation (nozzle B).  
2. This paper has conducted simulations for nozzle A and nozzle B at 100% load and 30% load under hot-state, the results indicating that the performance index of nozzle B is better than nozzle A.
3. The resistance coefficient of nozzle A will rise after the outer cover is blocked. The abrasion of the outer cover, the generation of a gap between the inner tube and the top of the outer cover, will reduce the resistance coefficient.
4. The small hole in the outlet of nozzle B is designed as a downward special shape, and the outlet velocity is evenly distributed. Therefore, the risk of the outer cover clogging is less than nozzle A.
5. The application results of a 480 t h\({}^{-1}\) CFB boiler show that the air nozzle replacement rate is reduced from 34.5% within 5000 h to 2.6% after replacing nozzle A with nozzle B, and the service life of the air nozzle is significantly extended.
6. The related research is of great value for the design and working characteristics evaluation of the bell-type air nozzle. The new bell-type air nozzle has important engineering application potential.  
Writing--Review & Editing, Z.H. and L.D.; Project administration, D.C.  
This study was supported by the Beijing Nova Program (XX2018033).  
[PERSON] and [PERSON] provided valuable advice on the study idea and write-up.  
The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, and in the decision to publish the results.
## 5 Performance Evaluation
### Simulation Results: Different Parameters' Effects on Replication Attack Detection
#### 5.2.2 Communication Overhead  
The total number of messages forwarded via mobile nodes in MWSN is described as Communication overhead. If mobile nodes (i.e., \(N\)) are receiving and delivering the data via messages and every single message must transfer by CH, \(1\times N\) would be the overall communication overhead in MWSN. For the proposed DT approach, it is \(O(N)\). Figure 7 screens that the overhead used for the proposed DT approach is lesser than that of other approaches. This is because the danger theory concept is built on cluster or cloud and every single mobile node must transfer the data to CH. Besides, \(O(N)\) depends upon the entirely used mobile nodes with direct proportion. Hence, if there is a rise in the quantity of mobile nodes, then communication overhead would also be increased. The result shows that the first level and second level of detection communication overhead increases with the number of mobile nodes. However, third level detection does not show salient changes because its task is to only forward the message about replica to the other BSs.  
Figure 6: Different stages of clone detection in MWSN.  
Figure 7: Communication overhead of Danger Theory (DT) approach.
# Image Analysis and Processing for Generating Camouflages from Digital Earth Photographs
## 4 Selected Technical Aspects of the Camouflage Generator Approach
### Logic Layer
#### 4.2.2 CammoGenerator Component
Figure 14: Sample SimplexNoise noise (on the **left**) and noise transformed with function (1) (on the **right**). Figure 15: Example of shape extraction algorithm (on the **left**) and example of combining labels of shape extraction algorithm (on the **right**). ```
1 FunctionCammoGeneratorComponentFShapeExtraction(\(shape_{i}\)):
2\(label=1\);
3 PickPoint();
4 CheckNeighboursLabels();
5 if\(labelList=empty\)then
6 SetLabelApoint();
7\(label++\);
8
9 else
10 ChooseTheLowestValueFromLabels();
11 AssignNeighborsTheirGroupLabel();
12 ifthere is another point = truethen
13 ChooseAnotherPoint();
14 GoT CheckNeighboursLabels();
15
16 else
17 GroupPointsByLabels();
```  
**Algorithm 2**CammoGenerator component--shape extraction function. After generating the shapes for each layer, a blank image is generated, over which the background color is applied. The shapes are then superimposed on the image in random order. The overlapping effect was easily achieved by mixing the order in which the stains were applied. The final stage of camouflage generation is its deformation, revealing squares of colors, called pixelation. This effect is achieved by dividing the image into squares of the selected size (for the CammoGenerator application, the square is 5), and then by determining the dominant color for each square. When selected, the squares are filled with their dominant color. The deformation function is shown in Algorithm 3. ```
1 FunctionCammoGeneratorComponentFDefinition(\(image_{i}\)):
2 divideImageIntoSquares();
3 choose Square;
4 whilethere is another squaredo
5 FindDominantColorInSquare();
6 SetColorInSquareToDominantColor();
7 choose Another Square;
```  
**Algorithm 3**CammoGenerator component--deformation function.
# Current Context and Research Trends in Linear DC-DC Converters
## 6 LDO's Recent Research Trends
### Improving the Transient Performance  
Transient responses have unique features that inherently connect to the application. Therefore, by considering the special properties of the application, LDOs can further be improved to withstand transients. Researchers are now focusing on developing LDOs for specific applications while considering the transient behaviours of the application [51]. [PERSON] et al. [51] reviewed the benefits of using analog and digital LDOs based on the environment and also discussed the advantages of using hybrid LDOs such as analog-assisted digital LDOs and digital-assisted analog LDOs.  
There are LDOs especially developed for flash memory systems [52]. A fully integrated digitally assisted LDO was proposed for NAND flash systems using a 500 nm I/O CMOS transistor. The proposed LDO's input voltage range is 2.3-3 V and output is 2.1 V and it is capable of achieving both fast transient response and highly accurate regulation in the steady state. The measured output voltage drop is 225 mV against a load current step fluctuation of 150 mA in 20 ns.  
[PERSON] et al. [53] proposed a nano-ampere LDO to be used in IoT devices considering their exact transient properties. As shown in Figure 8a,b, the proposed setup consists oftwo LDO setups where the input is 1 V and the output is 0.8 V. Figure 8a shows the LDO 1 which combines dynamic current biasing techniques to reduce the quiescent current, while Figure 8b shows the LDO 2 consisting of an inverter-based dynamic loop to further improve the transient response. This prototype was fabricated in a 65 nm low-leakage CMOS process and tested against a transient fluctuation of a load current stepped from 100 nA to 10 mA in 1 \(\upmu\)s transition time. The measured output voltage undershoot for LDO 1 is 336.8 mV, and 196 mV for LDO2.
## 3 Results  
The median follow-up was 99.7 months (IQR 80.2-115.3 months) and the mean period from index surgery to revision surgery was 36 months (range 9-72 months). The patients were predominantly women (63 patients) with a median BMI of 27.9 (IQR 25.3-31.6). The median age was 71.5 (IQR 65.1-74.9). The group with preoperative diagnosis of aseptic loosening consisted of 25 patients (29% of the total). In this group the median duration of the follow up was 105 months (IQR 89-118), the median value of the OKS was 39 (range 36-43), the median value of the EQ-VAS was 60 (IQR 51-66), the median value of the EQ-5D was 0.81 (IQR 0.74-0.85), the median value of the KSS was 84 (IQR 81-88), and the median value of the range of motion was 102\({}^{\circ}\) (IQR 94-109\({}^{\circ}\)). The group of with preoperative diagnosis of malpositioning included 24 patients (28% of the total); in this group the median duration of the follow up was 100 months (IQR 80-108), the median value of the OKS was 36 (IQR 26-41), the median value of the EQ-VAS was 56 (IQR 48-61), the median value of the EQ-5D was 0.72 (IQR 0.67-0.77), the median value of the KSS was 57 (IQR 50-66), and the median value of the range of motion was 94\({}^{\circ}\) (IQR 88-102\({}^{\circ}\)). The group with preoperative diagnosis of infection included 20 patients (24% of the total); in this group the median duration of the follow-up was 92 months (IQR 82-121), the median value of the OKS was 25 (IQR 17-35), the median value of the EQ-VAS was 43 (IQR 37-53), the median value of the EQ-5D was 0.44 (IQR 0.32-0.60), the median value of the KSS was 64 (IQR 53-71), and the median value of the range of motion was 89\({}^{\circ}\) (IQR 78-98\({}^{\circ}\)). The group with preoperative diagnosis of instability included 9 patients (11% of the total); in this group the median duration of the follow-up was 97 months (IQR 73-101), the median value of the OKS was 32 (IQR 27-35), the median value of the EQ-VAS was 39 (IQR 36-48), the median value of the EQ-5D was 0.77(IQR 0.75-0.85), the median value of the KSS was 66 (IQR 63-71), and the median value of the range of motion was 98\({}^{\circ}\) (IQR 85-104\({}^{\circ}\)). The group with preoperative diagnosis of periprosthetic fracture included 7 patients (8% of total); in this group the median duration of the follow-up was 102 months (IQR 88-125), the median value of the OKS was 44 (IQR 33-45), the median value of the EQ-VAS was 73 (IQR 67-78), the median value of the EQ-5D was 0.71 (IQR 0.68-0.74), the median value of the KSS was 83 (IQR 72-92), and the median value of the range of motion was 105\({}^{\circ}\) (IQR 96-111\({}^{\circ}\)). The preoperative diagnosis, the number of patients, the median follow-up for each subgroup, the PROMs, and the ROM are summarized in Table 1.  
The preoperative-cause-of-revision groups are similar in demographic features, as no significant differences was found (\(p>0.05\), Table 2).
# Validating the Use of Smart Glasses in Industrial Quality Control: A Case Study
## 1 Introduction
In the context of this project, assembly quality is the verification that components are in their correct position. This context underlines the critical importance of assembly quality to ensure seamless integration and functionality of a smart glasses-based quality control system. The verification process involves meticulous checks carried out by the system to confirm that each component is placed in the specified positions and meets the standards defined in the project. The primary objective is to develop an MR-based quality control system using smart glasses integrated with a server-based image recognition system and assess its effectiveness in a controlled environment. This study also aims to evaluate the system's performance and viability under real-world conditions, identifying problems and possibilities for improvement and verifying the feasibility of implementing this MR system on a larger operational scale in the manufacturing industry. This exploration aims to provide a practical roadmap for adopting MR in industrial quality control and contribute to the understanding and advancement of this technology. The subsequent sections offer an overview of object detection, detail the proposed methodology, present the pilot test results in a controlled environment, and conclude by summarizing essential findings, and emphasizing the significance of the proposed methodology for improving the quality control systems. The remainder of this paper is organized as follows. The next section provides an overview of object detection. Section 3 details the proposed methodology. Section 4 presents the pilot test carried out in a controlled environment where the intention is to evaluate the performance of the system, identify possible problems and evaluate its scalability. Section 5 concludes the paper by summarizing the essential findings and highlighting the significance of the proposed methodology in improving quality control system.
# Experimental Analysis of the Behavior of Mirror-like Objects in LiDAR-Based Robot Navigation
## 4 Methodology and Approach  
To investigate the challenges for a LiDAR-based robot localization system, our approach was to use a classical small-scale indoor autonomous robot with a mounted 2D LiDAR. Several mirrors were present in different positions within the developed experimental setup. Four experiments were conducted to investigate the effect of mirror reflection on the map constructed by the SLAM algorithm.
# Noise Reduction Using Active Vibration Control Methods in CAD/CAM Dental Milling Machines
## 4 Noise Reduction Solution  
### Experimental Verification by Vibration Reduction Method  
A final set of experiments was conducted to measure the sound cancellation achieved through experimentation in a laboratory setting. In order to verify the validity of noise reduction through the vibration control method, a recording and noise measurement environment were constructed through a computer program. The program was created so that the noise reduction results could be analyzed after creating an experimental environment for vibration control using recorded noise files. Since the strongest vibration occurred around the hose area of the dust collector, the tactile transducer was attached to the area in which the strongest vibration (A) was generated to record the greatest sound pressure. A tactile transducer that was used in manufacturing the equipment and can generate vibration is also called a 'vibration speaker'. Based on the principle that in the domain of low frequency, it is possible to feel with one's body, not with one's ears, this speaker can transmit low-frequency vibration to the surface it is attached to, since this has no diaphragm.  
In addition to the tactile transducer, a sensor was placed in the area in order to determine the vibrational frequency. The speaker reproduced a recorded sound source to simulate the vibration and noise generated by the dust collector. The tactile transducers reproduced anti-vibration with the sound of the same frequency and size emitted by the dust collector to control the vibration on the other side. The experimental set up is shown in Figure 8 and the noise control method and diagram are shown in Figures 9 and 10.  
Figure 6: Identifying the main noise source of milling machines.  
Figure 7: Internal structure of the dust collector.  
Figure 8: Experimental configuration.  
Figure 10: Vibration speaker installed at the dust collector.  
Figure 9: The diagram for the vibration reduction method.  
The result of the test demonstrated that it was possible to reduce the level of noise by only reducing vibration, because when the dust collector of the milling machine was used, vibration was transmitted to the surface of the dust collector by the compressor and the noise generated this time was dominant. Table 5 and Figure 11 indicate the result.
## 2 Vibration Characteristics of Idling Vehicles
### Fundamental Vibration Frequency Determination  
Modern internal combustion engines, both gasoline and diesel fueled, used in automotive applications are four-stroke engines. A complete cycle for a single cylinder comprises four phases or'strokes' which occur over two compete revolutions of the engine crank. These are explained below.  
1. [label=(0)]
2. Intake--The piston retracts towards bottom dead center (BDC) while the intake valves are open, allowing oxygenated atmospheric air into the piston's swept volume.
3. Compression--The intake valve(s) close as the piston returns to top dead center (TDC), compressing the trapped air. Fuel is injected into the cylinder during the compression phase--the exact quantity and timing dependent on multivariate engine operating parameters.
4. Combustion--The compressed air and fuel is ignited via spark or compression. The exothermic combustion drastically increases internal cylinder pressure, propelling the piston back toward BDC. This is also known as the 'power stroke.'
5. Exhaust--Following the combustion stroke, the piston again travels towards TDC, this time with exhaust valve(s) open, allowing the combustion gases to exit the cylinder into the vehicle's exhaust system. This resets the cylinder for the beginning of the next intake stroke.  
The combustion stroke of a cylinder is a significant contributor to overall engine vibration and occurs once every other revolution of the engine crank. Engine designs and operation vary, but common multi-cylinder arrangements uniformly shift cylinder combustion. An inline four-cylinder engine would then have one cylinder combustion stroke every 180 degrees of crank rotation. A generalized formula for an engine's fundamental combustion driven vibration frequency \(f_{c}\) is  
\[f_{c}=\Big{(}\frac{r}{60}\Big{)}\cdot\Big{(}\frac{n}{2}\Big{)}=\frac{rn}{120}, \tag{1}\]where \(r\) represents the engine rotations per minute (rpm) and \(n\) is the number of engine cylinders.
# Multipath Interference Impact Due to Fiber Mode Coupling in C+L+S Multiband Transmission Reach
## 4 Transmission Reach Assessment
### Impact of the Symbol Rate on the Transmission Reach  
In this sub-section, the maximum transmission reach in a C+L+S MB system impacted by MPI is assessed for three symbol rates--32, 64, and 128 Gbaud. In Table 1, the channel bandwidth, the number of channels per band, and the total number of channels used for the three symbol rates are presented.  
The procedure to assess the transmission reach presented in Section 4.2 is followed for the 32 and 128 Gbaud scenarios, and it can be concluded that the optimum channel power levels, the ones that maximize the GSNR, are, respectively, 2 dBm and 4 dBm for the 32 and 128 Gbaud symbol rates, as indicated in Table 1.  
The number of spans, as a function of the MPI/span for the three symbol rates, was computed, assuming the same ROSNRs used in the previous sub-section. It can be concluded that the symbol rate does not affect the transmission reach as a function of the MPI/span for the S-band. Only for QPSK signals with 32 Gbaud, in the hypothetical L-band scenario, can a slightly greater transmission distance be achieved when the MPI/span is smaller than \(-34\) dB/span in comparison with the 128 Gbaud scenario, as can be observed in Table 4. It is also observed that the symbol rate does not affect the transmission reach as a function of the MPI/span for 16-QAM signals.  
Figure 8: Number of spans as a function of the MPI level per span for the three bands, considering QPSK and 16-QAM signals.
###### Abstract  
This paper deals with the potential of Third Generation Partnership (3 GPP) Project mobile cellular standards to enable vehicular communications. Starting from 3 GPP Release 15, and Release 16 specifications for Vehicle-to-Everything (V2X) communications, the different communication modes, interfaces and use cases for V2X based on Long Term Evolution (LTE) and New Radio (NR) are analyzed. This research also studies the potential beneficial impact on V2X of a network that is aware of the underlying Multi-RAT Dual Connectivity (MR-DC) architecture. The methodology followed in this work consists of a review of 3 GPP standards for vehicular communications based on mobile networks. The performance evaluation of the communication modes was performed through simulations taking into account resource allocation schemes, packet transmission frequencies, packet size, vehicle density and other parameters defined in the standard. In order to perform simulations of the decentralized communication mode (mode 4), a simulator based on OMNeT++ was configured. For the centralized mode (mode 3), an analytical model in MATLAB was used to configure different simulation scenarios. The results obtained indicate that LTE networks can only support basic V2X use cases because they do not demand strict potential requirements. Simulations showed that the centralized mode offers better performance than mode 4; however, it requires cellular network coverage. More advanced use cases are key for a future Intelligent Transport System (ITS), high-performance networks (i.e., Fifth Generation (5G), NR) are expected to coexist gradually with LTE in the V2X landscape. Therefore, in order to meet the strict requirements for latency, transmission speed and reliability, MR-DC architectures combining different radio access technologies, communication modes and connection interfaces should be deployed. In addition, operation in multi-operator and cross-border scenarios must be guaranteed.  
C V2X; LTE V2X; NR V2X; MR-DC; 3 GPP; Rel-16 2022