esa-sceva/satcom-chunk-collection huggingface dataset:
# Heterogeneous Parallel Implementation of Large-Scale Numerical Simulation of Saint-Venant Equations
## 5 Conclusions  
In this work, two-dimensional Saint-Venant equations were implemented by using the leapfrog-style finite difference method for the purpose of studying flood behavior. Large-scale heterogeneous parallel solution is implemented using MPI, OpenMP, Pthread, and OpenCL runtime libraries. The heterogeneous strategy is optimized by overlapping communication calculation, setting up work groups, etc., and performance tests from various perspectives are also carried out. Finally, a large-scale heterogeneous parallel solution for 2D SV equations with good performance is obtained. In the future, we hope that our work can become a large-scale heterogeneous parallel solution framework capable of solving SV equations -like PDE. For example, the heat conduction equation as an important PDE should also be able to use our computational framework. It describes how the temperature in a region changes with time, and like the Saint-Venant equation, it is difficult to obtain analytical solutions, and numerical methods are usually used to obtain numerical solutions. There are also some other problems that may also be able to use our computational framework, such as phase transitions, elasticity, electrical potential, etc. The purpose of our current research is to propose a massively heterogeneous parallel framework based on Saint-Venant's equations in domestic advanced computing systems. Therefore, a simple model is used to facilitate heterogeneous parallel implementation. In the future work, we will consider more complex and more types of models to simulate various actual situations (such as floods, tsunamis, dam failures, etc.).  
Conceptualization, Q.L. and N.N.; methodology, Q.L. and N.N.; software, Y.Q.; validation, L.G., W.Y. and Z.L.; formal analysis, Q.L.; investigation, Y.Q.; resources, Q.L.; data curation, Y.Q. and X.S.; writing--original draft preparation, Y.Q.; writing--review and editing, Q.L., Z.Z. and J.Z.; visualization, Y.Q. and S.T.; supervision, Q.L.; project administration, N.N. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the National Key R&D Program of China (Grant No. 2020 YFB1709501), GHFund A (No. 20210701) and the Shandong Province Natural Science Foundation (Grant No. ZR201910310143).  
Not applicable.  
The authors declare no conflict of interest.  
Figure 16: Single CPU vs. 4 accelerators comparison chart.
## 2 Definitions and Main Results  
A _string puzzle_ is composed of looped _strings_ and a rectangular _board_ with holes embedded in the \(3\)-dimensional Euclidean space. Strings are entangled with each other and with the board through the holes. One of the strings is called the _target string_. A string puzzle is said to be _solvable_ if the target string can be disentangled from the board and another set of strings without cutting strings or deforming, whittling, or breaking the board.  
We can freely bend and fold strings into desired shapes, but we cannot cut any string. We assume that the diameter of every string is negligibly small. Nevertheless, we further assume that the length of any string cannot be increased even under high tension.  
The input of the generalized string puzzle problem is the initial layout of the board and strings, which must be represented by a sequence over \(\{0,1\}\) on the input tape of a Turing machine. The layout of the rectangular board is represented by the coordinates of the eight vertices (corners) in the \(3\)-dimensional Euclidean space. Holes of the board in this paper are empty spaces in the board whose shapes are polyhedrons such that each polyhedron has one face in the surface of the board and has another face in the reverse face of the board. All vertices of the hole-polyhedrons are supposed to be on the face of the board and not inside. (For example, holes of the board of Figure 1(a) are rectangular prisms, and those of Figure 1(c) are a 10-hedron and a rectangular prism.) Each polyhedron is represented by a set of its faces, where each face is represented by a sequence of the coordinates of the vertices.  
The initial layout of strings is given as follows. We assume that a string is initially strained and folded at points on the string (see red and blue strings of Figure 2(a)). A string is represented as a sequence of line segments. Every segment extreme is shared by exactly one other segment (adjacent segment). Thus,  
Figure 1: (**a**) A board having two holes. A looped string goes through A and B; (**b**) Lateral view of (**a**); (**c**) A board having hole C and a corridor connecting D to G; (**d**) The string can be moved from D to E by smoothing out the slack \(2d\); (**e**) The string is moved from E to G. The amount of slack becomes \(2d\) when the string reaches G.  
Figure 2: (**a**) A gadget simulating variable \(x_{i}\); (**b**) Simplified illustration of (**a**).  
every string can be represented by a sequence of the coordinates of segment extremes. We consider a string puzzle of which the board, holes, and strings have integral coordinates.  
Now we are ready to present our main result.  
**Theorem 1**: _There is a polynomial-time transformation from an arbitrary instance \(f\) of the 3 SAT problem to a string puzzle \(s\) such that \(f\) is satisfiable if and only if \(s\) is solvable._  
**Corollary 1**: _The generalized string puzzle problem is NP-hard._  
The proof of Theorem 1 is given in the following section.
# A Terminal-Oriented Distributed Traffic Flow Splitting Strategy for Multi-Service of V2X Networks
## 2 Related Works
### Queue-Based Service Shunting  
Queuing theory can effectively analyze and simulate the dynamic behavior of data packets in a link. Multiple service data streams are queued in sequence to wait for processing by the processing unit, thereby improving data transmission efficiency. The processing unit does not consider the structure or characteristics of the traffic flow, i.e., it acts as a \"black box.\" Its function for data streams is to analyze processing and path selection, and finally to distribute the data stream to different links.  
The adaptive traffic distribution mechanism based on a WLAN and wireless personal area network is studied in [23]. By modeling the transmission of data traffic between networks into a queuing system, the system transmission delay is minimized, thereby achieving load balancing [24; 25]. Some literature [25] has also presented a probability-split algorithm that minimizes delay in heterogeneous wireless networks. Some literature [26] proposes an optimal distribution scheme based on dynamic traffic allocation in heterogeneous wireless network environments. This scheme aims to minimize the queue delay while maximizing the probability of a packet arriving at a given delay constraint. In order to support multiple users with multiple services, a resource allocation and burst scheduling algorithm for HPC (Highest Priority-Controlled)-DRX (Discontinuous Reception)/TRTS (Traffic Regulation plus Time Slicing) is introduced. The lower priority traffic never wakes up the user equipment (UE), and all incoming traffic of the UE is temporarily buffered at the evolved Node B (eNB), and then transmitted in burst mode using the total bandwidth, resulting in better power-saving performance. The power-saving rate of the proposed mechanism is theoretically analyzed based on the M/G/1 busy period model [27].  
Therefore, the analytic hierarchy process, priority control, and queuing methods for service shunting technology are always analyzed separately, which leads to a lack of a comprehensive solution. In this paper, we consider the advantages of the above methods and consider the service characteristics of the vehicular network terminal. Specifically, we first assign different weights according to different services. Then, the heterogeneous wireless sub-network is regarded as a plurality of different parallel queuing systems to model the service shunt problem as the joint optimization problem of delay and cost consumption. The proposed traffic flow splitting algorithm can achieve the optimization of transmission delay and service cost.
###### Abstract  
Delamination in laminated structures is a concern in high-performance structural applications, which challenges the latest non-destructive testing techniques. This study assesses the delamination damage in the glass fiber-reinforced laminated composite structures using structural health monitoring techniques. Glass fiber-reinforced rectangular laminate composite plates with and without delamination were considered to obtain the forced vibration response using an in-house developed finite element model. The damage was diagnosed in the laminated composite using machine learning algorithms through statistical information extracted from the forced vibration response. Using an attribute evaluator, the features that made the greatest contribution were identified from the extracted features. The selected features were further classified using machine learning algorithms, such as decision tree, random forest, naive Bayes, and Bayes net algorithms, to diagnose the damage in the laminated structure. The decision tree method was found to be a computationally effective model in diagnosing the delamination of the composite structure. The effectiveness of the finite element model was further validated with the experimental results, obtained from modal analysis using fabricated laminated and delaminated composite plates. Our proposed model showed 98.5% accuracy in diagnosing the damage in the fabricated composite structure. Hence, this research work motivates the development of online prognostic and health monitoring modules for detecting early damage to prevent catastrophic failures of structures.  
machine learning; statistical features; fault diagnosis; delamination; composites; vibration
# Research Progress and Applications of 2D Antimonene
## 3 Practical Applications  
### In Composite Materials  
The doping of antimonene nanosheets in the graphene-based composite sponge promotes the electrolyte interactions at the interface due to the high surface area of the antimonene layered structure. When the antimonene is distributed on the surface or inside the matrix, it can ensure the free movement of carriers, thereby improving the overall electrochemical performance and sensitivity of the material by 44%, while maintaining the conductivity of the material. [PERSON] et al. [11] prepared antimonene/graphene composite sponges with regular pore structure of melamine sponge as substrate. The crucible containing the graphene intercalation compound was heated to 700 \({}^{\circ}\)C for 3-4 min. After cooling, the graphene sheets were then placed in acetone for ultrasonic treatment. The graphene films were then dried at 25 \({}^{\circ}\)C for 3-4 h. The antimonene solution was obtained by grinding,  
Figure 11: (**a**) Schematic diagram of laser irradiation; (**b**) The results of the open–hole Z–scan experiment. Reprinted with permission from Ref. [25]. Copyright 2020, American Institute of Physics.  
adding deionized water and ED-2003 solution for ultrasonic and centrifugal treatments. Then, the modified graphene sheet and antimonene solution were mixed by solution blending method, and attached to the sponge bone evenly. Then. PVA/KOH gel was installed between the two sponge electrodes as electrolyte and separator. The antimonene/graphene composite sponge is used as a supercapacitor and capacitor sensor. During the preparation of the capacitive sensor, conductive carbon cloth and solid electrolyte were introduced to assemble the flexible wearable sensor. The resulting pressure sensor has good sensitivity, high flexibility and high mechanical, temperature and sensing stability. The pressure sensor has been successfully applied to the supercapacitor and human motion monitor. In order to achieve the integration goal, the functional devices are connected to the sensor and the supercapacitor, as shown in Figure 12a,b. When the mechanical pressure is applied, the sensor is compressed, resulting in a sharp increase in the current. The sensors are mounted on the fingers and wrists, and when pressure is applied to the fingers, they show an electric current to detect movement signals such as distortion of the fingers and wrists.  
[PERSON] et al. [63] also calculated the electronic and optical properties of the composite germanene and antimonene nanosheets theoretically. Ge/Sb bilayer is constructed, and it is determined that the d orbitals of Ge and Sb almost overlap in the whole energy range, indicating that their monolayers can be combined with each other through orbital hybridization, resulting in strong bonding strength. In addition, the introduction of external electric field can also adjust the band gap, and its structural work function is calculated to be 4.49 eV. This composite material has application potential in field reflection devices.
# Vision-Guided Hierarchical Control and Autonomous Positioning for Aerial Manipulator
## 4 Autonomous Positioning and Grasping
### SLAM-Based Autonomous Positioning and Navigation System
#### 4.1.1 System Framework of the LiDAR SLAM-Based Positioning Method  
The SLAM-based positioning method combines the high-precision autonomous positioning requirements of the aerial manipulator, comprising three parts: LiDAR odometry [35], IMU module, and back-end optimization. The overall framework is illustrated in Figure 5.
## 3 Results and Discussion
### A Model for the LIFTOP Process of the Fn-CaP Film  
Why is the LIFTOP process able to transfer brittle materials even onto hard receiver substrates while maintaining their film shape? One of the possible explanations is shown in Figure 4, which shows the possible models for the Fn-CaP film transfer by the (a) LIFTOP process and (b) LIFT. For both cases, a single nanosecond laser pulse was irradiated on the Fn-CaP donor film through the (a) carbon-coated optical stamp or (b) carbon-coated PET support. This led to the strong laser absorption at the carbon layer. Then, laser-induced phenomena, such as the laser ablation of carbon, caused the donor film transfer. In the case of (a) LIFTOP, there was little gap between the donor film and the PET receiver substrate due to the soft PDMS layer on the PET support, which protected the ejected film from fracturing during flight. Further, PDMS is an excellent shock absorber, which possibly helped in diminishing the impact that the donor film would receive during deposition. On the contrary, in the  
Figure 3: (a) Schematic image of the LIFTOP process (upper) and a confocal laser scanning microscopic image of the Fn-CaP microchips transferred onto the PET receiver substrate by the LIFTOP process (lower). For comparison, the Fn-CaP film was transferred by the laser-induced forward transfer process without the optical stamp, as shown in (b).  
case of (b), there was a native gap between the donor film and the PET receiver substrate due to the absence of PDMS on the hard PET support, which has poor shock-absorbing ability. Consequently, the Fn-CaP film tends to fracture during LIFT. Thus, from the above model, the transfer without donor film disruption can be realized by the LIFTOP process.  
The present LIFTOP process is based on single-shot irradiation and absorption of a low-energy nanosecond laser pulse in the carbon sacrificial layer in the Fn-CaP/C/PDMS/PET donor sample, which is basically the same as the LIFT process in our previous report [16]. In our previous work [16], the CHO-K1 cell culture experiments revealed the better cytocompatibility of Fn-apatite microchips prepared on a PDMS receiver substrate by LIFT using the C/PET support (with a carbon sacrificial layer), compared to apatite microchips without Fn. This result suggests that the Fn protein in the Fn-apatite donor film retained its cell adhesion activity even after the LIFT process. In the present LIFTOP process using the C/PDMS/PET support, the optically transparent PDMS layer should have no significant effect on laser-induced phenomena in the carbon sacrificial layer such as ablation and heat generation. Therefore, the LIFTOP process as well as the LIFT process is considered to be effective in the transfer of protein-immobilized CaP films without fatal protein inactivation. Anyway, further investigation on the effect of the LIFTOP process on the microchip properties, such as bioactivity, chemical composition (Ca/P ratio, Fn content, etc.), and crystallinity, will be proceeded in our future work.
## 3 Materials and Methods
### Software and Fundamentals of SfM-MVS Photogrammetry
Although its mathematical foundations will be explained in detail in later sections, it can be anticipated that it mainly consists of the application of filters to eliminate noise or improve the focus of the images. Once a body of photographs is available, it is uploaded into Metashape, where the first step consists of aligning the images, i.e., finding the common points (tie points) between them that generate a sparse point cloud. This initial point cloud is not dense enough to form a mesh to support the model. The SfM-MVS algorithms are again in charge of densifying it, until a dense point cloud has been obtained. The meshing process consists of the creation of a mesh of triangular elements that join the points of the dense cloud. Once the mesh has been constructed, the three-dimensional model is visible. However, its surface does not have the texture of the real object or structure. In order for the final results to have the right texture, the pattern defined by the photographs is used. To facilitate the understanding of the process, Figure 7 shows 3 screenshots of the RGB model from the sparse point cloud to the final model.
## 4 Experimental Results and Discussion  
### Performance of Proposed Power Control Strategies  
In order to demonstrate the effectiveness and applicability of the proposed power control strategies, algorithms were performed using MATLAB Simulink. At first, the simulations were carried out to investigate the performances of the WT under varying step sizes for each algorithm. Due to the constraints linked to the characteristics of the WT studied in this work, two points, LPP1 and LPP2, allow for reaching the same power for a specific wind velocity. They are examined in Figure 8. Thus, the wind speed is fixed at 6.5 m/s and the limited power (\(P_{\text{lim}}\)) at 50 W, which is under the maximal power provided in this case. After studying the performances of each proposed control strategy, a comparison of the results with a specific step size is carried out.
# Vehicle Collision Prediction under Reduced Visibility Conditions
## 3 Visibility-Based Collision Warning System Design
### Velocity Prediction Model  
Velocities for SV and LV are both predicted using a back propagation neural network (BPNN), which consists of 3 layers namely input, hidden, and output. Past velocities in the time slots \(t-n\) to \(t\) (current time slot) are used as input data for training the model so as to predict the velocities in the future time slot \(t+1\). The output layer uses hyperbolic tangent sigmoid transfer function. The training samples is about 125,260 and the velocity range is from 0 ft to 100 ft.
# Advanced Medical Image Segmentation Enhancement:
## 2 Related Works
### Enhancement Techniques  
Enhancement techniques are pivotal for elevating image quality and facilitating subsequent segmentation processes [47]. These techniques aim to enhance contrast and improve overall image visibility in order to contribute to more effective segmentation outcomes [48; 49].  
One avenue of research explores the enhancement of medical image segmentation through adaptive histogram equalization [50], highlighting its potential for contrast improvement [23; 29; 51]. Additionally, a comprehensive survey has delved into image enhancement techniques within medical imaging [52]. This survey provides valuable insights into various methods to address challenges such as non-uniform illumination and noise in medical images [53]. This foundational overview of image enhancement techniques is essential for understanding strategies to improve the quality of medical images prior to the segmentation process.
# Phase Shift Design in RIS Empowered Wireless Networks: From Optimization to AI-Based Methods
## 3 Review on Optimization Methods under Continuous Phase Shift  
Currently, the major techniques for optimizing the continuous phase shifts are the SDR method, penalty method, MM method, GD method, manifold method, and CR method. All the reviewed methods are primarily developed for C1 and can be applied to C2 if \(\beta_{m}\) and \(\theta_{m}\) are optimized separately. For C3, this is handled by the GD method due to the complicated dependence of \(\beta_{m}\) on \(\theta_{m}\). Table 3 provides a quick summary of the reviewed methods in this section.
## 5 Conclusions  
In this paper, a novel space-borne high-resolution SAR system with non-uniform hybrid sampling technology is proposed. The non-uniform hybrid sampling technology is firstly applied in SAR imaging system for the detection of space targets. By means of optimizing the transmitted and receiving timing of SAR signals, the non-uniform hybrid sampling technology is able to reduce the requirement of the sampling rate of ADC for the reception of the wideband echoes from space targets. In the paper, compared with the requirement of Nyquist sampling theorem, the sampling rate of ADC can be reduced four times through the non-uniform hybrid sampling technology. Simulated results with different targets and different non-uniform hybrid sampling parameters were compared, indicating that the imaging quality using non-uniform hybrid sampling with an interval of 15 us is consistent with imaging result of the Nyquist real-time sampling. An X-band SAR imaging experimental system was constructed, and the experimental results showed that the imaging resolution of the SAR system is better than 8 cm, satisfying the requirement of high-resolution imaging for space targets.  
Conceptualization, Z.X. and S.J.; Data curation, Z.Z. and C.Z.; Formal analysis, C.Z.; Funding acquisition, Z.X.; Investigation, Z.X. and C.Z.; Methodology, Z.X. and F.Y.; Project administration, Z.X.; Resources, W.G. and T.Z.; Software, J.Y. and Z.Z.; Supervision, Y.Z.; Validation, Z.X. and Q.Z.; Visualization, X.L. and T.P.; Writing--original draft, C.Z.; Writing--review & editing, Z.X., J.Y., C.Z. and X.L. All authors have read and agreed to the published version of the manuscript.  
This research work was supported by Innovation Funds of Equipment Pre-Research under Grant JZXY720190253036001 and JZXY720190253040601.  
The authors declare no conflict of interest.