esa-sceva/satcom-chunk-collection huggingface dataset:
# Electromagnetic Particle Algorithm for Beam-Wave Interaction in Traveling Wave Tube of Symmetry
###### Abstract  
In many fields, such as space astrophysics, plasma and vacuum electronics, there are many nonlinear strong coupling physical problems. In order to solve the problem of electron beam-wave interaction in cylindrical Traveling wave tube (TWT) with symmetrical structure, a multi particle simulation algorithm for beam circuit is designed. The algorithm allows aperiodic time input, nonuniform linearity and large space diagnosis for different particles. In this algorithm, the field of coupled slow-wave transmission line is simulated by finite difference method. Assuming that there is strong coupling between the beam and the circuit, the space center equation of transmission along the line is obtained, and the space charge field is modeled considering the space charge effect, which can easily be ignored. The Particle In Cell (PIC) method of frog leaping step scheme is adopted to evaluate the electric field of each particle center, determine the circuit and space charge field, and design the termination part to compensate for the loss in order to avoid self-excited agitation. Finally, a simple numerical simulation is carried out for the electromagnetic problem and the accuracy of the code is checked against the electromagnetic simulator CHPIC. Therefore, the algorithm can be used to solve the problem of beam-wave interactions in a fixed structure (cylindrical) in multiple fields and can accurately record the data in the process.  
cylindrical traveling wave tube; electromagnetic particle simulation; finite difference +
Footnote †: journal:  
1
Footnote 1: College of Mathematical Sciences, Harbin Engineering University, Harbin 150001, China  
2 College of Intelligent Systems Science and Engineering, Harbin Engineering University, Harbin 150001, China  
3 Beijing Institute of Spacecraft System Engineering, 104 Youyi Road, Haidian District, Beijing 100094, China  
* Correspondence: [EMAIL_ADDRESS]; Tel.: +86-15536983461
# GPSR: Gradient-Prior-Based Network for Image Super-Resolution
## 2 Related Work
### Contextual Residual Feature  
As the network depth increases, multi-level contextual residual features, which are hierarchical with different receptive fields, can benefit SR from different perspectives. However, numerous deep-learning-based SR methods, such as VDSR [24], EDSR [10], SAN [15], PA-EDSR [14], NLSN [13], etc., constitute a deep network by simply stacking a massive quantity of residual modules, but they do not fully utilize the complementary contextual residual features, limiting the SR performance. To improve the information flow, [PERSON] et al. [25] proposed a densely connected convolutional network (DenseNet), which uses dense connectivity to achieve a direct connection between any two layers, significantly improving the efficiency of feature and gradient information transfer, and reducing the training difficulty. However, DenseNet is unsuitable for the SR task. On the one hand, the Batch-Normalization (BN) layers severely corrupt the contrast information of the reconstructed images. On the other hand, the pooling operation may lose crucial spatial information. To address this issue, [PERSON] et al. [11] designed a Residual Dense Block (RDB), which densely connects abundant local features to generate more advanced fused features while removing modules that negatively impact on the SR task. Nevertheless, over-dense connections and over-frequent concatenation operations not only require a large amount of computing resources, but they also introduce redundant feature information which hinders the feature representation. To reduce the heavy computation burden, [PERSON] et al. [26] proposed a Residual Feature Aggregation framework (RFA). Compared with RDB, RFA removes unnecessary skip connections and directly forwards the features on each local residual branch to the end of the network, leading to a better SR performance. Additionally, inspired by the feedback mechanism that permits the network to carry a signal of output to correct previous states, [PERSON] et al. [27] propose an image Super-Resolution FeedBack Network(SRFBN) to refine low-level representations with high-level information in a top-down manner to promote the SR performance. The above studies [11; 25; 26; 27] have shown that the rational exploration and utilization of contextual residual features can provide more helpful information for the SR task. However, due to the lack of discriminative learning capability, a considerable number of redundant features may be passed to the end of the network and hinder the SR performance.
## 3 Experimental Setup  
The experimental setup in this study is shown in Figure 3a. An induction heating system (EasyHeat 0224, Ambrell, NY, USA) is used for thermal excitation. In order to fit the complex geometry of a PDC bit, the excitation coil is designed as an annular coil as shown in Figure 3b. The induction heating system provides a maximum excitation power of 2.4 kW, a maximum output current of 380 A, and an excitation frequency range of 150-400 kHz. The temperature response of the specimen surface is recorded by an infrared camera (SAT-HY6850) with 320 \(\times\) 240 pixels at a frame rate of 25 Hz and a spatial resolution of 1.3 rad. The thermal sensitivity of the camera is 80 mK and the accuracy is \(\pm\)2%.  
A PDC bit retired from oil drilling field is used as experimental specimen in this study, as shown in Figure 4a. A PDC bit is comprised of three parts: a PDC cutter, a tungsten carbide matrix, and the joint. There are two crossed surface cracks on the tungsten carbide matrix, which are labeled as Crack I and Crack II, as shown in Figure 4b. Their widths are both less than 0.2 mm, which makes it very difficult for direct visual observation. The lengths of Crack I and Crack II are 88 mm and 21 mm, respectively. Figure 4c shows the zoomed view of Crack I. The polycrystalline diamond compact cutter comprises a thin layer of sintered polycrystalline diamond bonded to a tungsten carbide-cobalt substrate. The tungsten carbide matrix is one kind of alloy steel that mainly includes W, Fe, T.C, F.C, Si, Ni, Co, and other components. Its electrical conductivity is about \(5.21\times 10^{6}\) S/m and thermal conductivity is 0.42 W/(cm\(\cdot\)K). The conductivity of tungsten carbide makes it possible to heat the PDC bit matrix by induction heating.  
Figure 4: _Cont._  
Figure 3: Experimental setup: (**a**) each part of the experimental system; (**b**) zoomed view of the excitation coil.  
From Figure 3a, we can see that the size of the annular coil is too small to detect the surface cracks on the bit matrix. Additionally, the power of the induction heating system is also limited for exciting the whole bit at one time. Therefore, as discussed in Section 2.1, ECPT can be applied to detect the cracks in a successive scanning manner. As shown in Figure 4b, the induction coil was successively moved from Position A to Position E in such a way: the induction coil was moved 20 mm each time and heat the PDC bit for 500 ms followed by a cooling time of 3.5 s at each position. Additionally, the recording process of the IR camera is an ongoing process during the detection for the five positions. After the excitation coil scanning the whole surface of bit matrix, each segment of each surface crack can be roughly detected in sequence.
## 4 Results and Discussions
### Gust Factor  
The gust factor in steady wind conditions depends on several wind characteristics, such as the intensity and integral scale, hence, it is a basic representation of the dynamic properties of wind loads [49]. Figure 7 depicts the gust factors and the corresponding probability distribution of typhoon  
Figure 5: Peak factors and their PDF for typhoons.  
Figure 6: Peak factors and their PDF for hurricanes.  
winds obtained based on the unified analysis framework. For typhoons, the average value of gust factors is 1.4919 and the standard deviation is 0.0069. The gust factors of hurricanes are presented in Figure 8a, where the gust factors have a mean of 1.4787 and a standard deviation of 0.0071. The mean of gust factors for typhoons are slightly higher than that for hurricanes, while the standard deviations of gust factors for typhoons and hurricanes are almost identical with similar probability distribution shapes. The probability distribution of gust factors for typhoons follows the extreme value distribution with a location parameter of 1.4948 and a scale parameter of 0.0051, while the probability distribution of gust factors for hurricanes follows the generalized extreme value distribution with shape parameter of \(-0.5535\), location parameter of 1.4771, and scale parameter of 0.0076.  
In ASCE7-10, the calculation of gust factor is referenced to the gust factor curve proposed by [PERSON] [50]. The averaging time of the mean wind speed is 1 h in the [PERSON] gust factor curve, while the gust factor is calculated based on an averaging time of 10 min in this study. Therefore, the conversion scheme for the gust factors with different averaging times presented in [PERSON] and Sherlj [20] was utilized here. Gust factor with a duration of 3 s and an averaging time of 10 min can be expressed as:  
\[G_{u}=1+(SU)[SD(600,\ 3)], \tag{41}\]  
where \(SU\) is the value of the standard normal deviation associated with the exceedance probability of 0.5% and equals to 2.575. The \(SD(600,\ 3)\) could be estimated by the following formula:  
\[SD(600,\ 3)=\Big{[}SD^{2}(3600,\ 3)-SD^{2}(3600,\ 600)\Big{]}^{1/2}, \tag{42}\]  
where \(SD(3600,\ 3)\) and \(SD(3600,\ 600)\) can be interpolated as indicated in [PERSON] and Sherlj [20] and equal to 0.1617 and 0.0650, respectively. The gust factor with duration of 3 s and averaging time of 10 min based on Equations (37) and (38) is around 1.3814, which indicates that the gust factors for both typhoons and hurricanes are greater than those for extratropical storms.  
Figure 8: Gust factors for hurricanes.  
Figure 7: Gust factors for typhoons.
## 4 Discussion and Conclusions
Hence, due to the scope of this article, the impact of the navigation system on firefighters' tactics will not be broadly discussed. Currently, the fire service is looking for a solution to the indoor navigation. Therefore, there is a great need to create such a system. Drawing paths in different colors for different firefighters and displaying these paths on the tablet, laptop or phone to the commander would enable firefighters to be located in buildings. In the case when one of the firefighters needs help, it provides the lost firefighter's trail. Future research should focus on testing the device for navigation in buildings with a more complex structure and in several-story buildings. In these tests we proposed slight changes to firefighters' tactics, such as asking them to leave the anchors in characteristic places such as the entrances to apartments or staircases. Each time a firefighter passes near the anchor (during search and rescue), the position is corrected and error is reset. These assumptions allow us to perceive the building as a superposition of it smaller parts. This way our experiments on less complicated layouts make more sense. In addition, the tests should be carried out under conditions of artificial smoke, so that firefighters can enter the building with air cameras. It is also necessary to conduct tests with improved devices, i.e., using two anchors spaced several meters apart, in order to improve the estimation of the pathway established by the inertial system. [PERSON] is responsible for the concept of the algorithm and its implementation. [PERSON] is responsible for the hardware and software related to the data acquisition and transmission. All of the authors are equally involved in the tests. 2017 Donald J. Burns Memorial Research Grant awarded by: Society of Fire Protection Engineers founded by: Bentley Systems. The authors wish to express their most sincere gratitude towards the Society of Fire Protection Engineers, Bentley Systems and the jury that awarded the 2017 Chief Donald J. Burns Memorial Research Grant. The authors are also grateful to the company ConsultRisk sp. z o. o. for facilitating publication of this article. Additionally, the researchers thank [PERSON] and [PERSON] for their support in preparing the tests of the system. The authors declare no conflict of interest. The following abbreviations are used in this manuscript: \begin{tabular}{l l} BLE & Bluetooth Low Energy \\ CAD & Computer Aided Design \\ CHAIN & Cardinal Heading Aided Inertial Navigation \\ DAU & Data Acquisition Unit \\ DR & Dead Reckoning \\ GCS & Global coordinate system \\ GNSS & Global Navigation Satellite System \\ GPS & Global Positioning System \\ INS & Inertial Navigation System \\ IPSN & International Conference on Information Processing in Sensor Networks \\ LCS & Local coordinate system \\ MEMS & Micro Electro Mechanical Sensor \\ RSSI & Received Signal Strength Indicator \\ MAPN & Map-Aided Pedestrian/Individual Navigation \\ ORCA & Optimal Reciprocal Collision Avoidance \\ RMSE & Root Mean Squared Error \\ ToF & Time-of-Flight \\ UWB & Ultra Wide Band \\ \end{tabular}
# Flavonoids as Promising Multitarget Agents in Alzheimer's Disease Therapy
## 2 Activities of Flavonoids from Natural Sources
### Inhibition of A\(\beta\) Production
#### 2.1.4 Flavonols  
Kaempfer, the 3,\(A^{\prime}\),5,7-tetrahydrooxyflavone (**76**), exhibits a BACE1 IC\({}_{50}\) of 14.70 uM. Comparing with apigenin (**29**) (IC\({}_{50}\) = 38.50 uM) it can be concluded that the hydroxy group on C3 is important for the hydrophilic binding to BACE1 of flavonoids [52]. Quercetin, the 3,3\({}^{\prime}\),4\({}^{\prime}\),5,7-pentahydroxyl flavone (**1**, Figure 3), isolated from several plants, such as _Allium copa_ L. and _Malus punilla_ Mill., presents an IC\({}_{50}\) of 5.40 uM [50; 51; 52] and morin, the 2\({}^{\prime}\),3,4\({}^{\prime}\),5,7-pentahydroxyl flavone (77), isolated from _Psidium guajava_[53], has an IC\({}_{50}\) of 21.70 uM [52], suggesting once more the significant role of the hydroxy group on C4\({}^{\prime}\) for the hydrogen bonds. When there are two hydroxy groups on ring B they should be in the _ortho_ position. Myricetin, the 3,3\({}^{\prime}\),4\({}^{\prime}\),5,5\({}^{\prime}\),7-hexahhydroxyflavone (**78**), which exists in _Ficus auriculata_, _Ardisia sanguilonenta_ and many other plants, shows an increase in the  
Figure 7: **(a)** Structure of flavones that inhibit \(\beta\)-secretase and of the inactive flavones **44** and **45**. **(b)** Structure of flavones that inhibit \(\beta\)-secretase and of the inactive flavones **55–57** and **67–73**.  
inhibitory activity against BACE1 (IC\({}_{50}\) = 2.40 uM) [52], suggesting that the six hydroxy groups improve the hydrogen binding to the enzyme.  
Isolated from the plant _Sophora flavscens_, sophoflavescenol, the 3,4\({}^{\prime}\),7-trihydroxy-5-methoxy-8-(3-methylbut-2-enyl)flavone (**79**), icaritin, the 3,5,7-trihydroxy-4\({}^{\prime}\)-methoxy-8-(3-methylbut-2-enyl)flavone (**80**), desmethylandroicaritin or 3,4\({}^{\prime}\),5,7-tetrahydro-8-(3-methylbut-2-enyl)flavone (**81**), and kushenol C, the 2\({}^{\prime}\),3,4\({}^{\prime}\),5,7-pentahydro-8-[(2\(R\))-5-methyl-2-prop-1-en-2-ylhex-4-enyl]flavone (**82**), presented BACE1 IC\({}_{50}\) values of 10.98, 22.48, 1.51 [89] and 5.45 uM [68], respectively. These results suggest the importance of the hydroxy groups at C4\({}^{\prime}\) and C5 when desmethylanhydroicaritin (**81**) is compared with icaritin (**80**) or sophoflavescenol (**79**). The results obtained for Kushenol C (**82**) and desmethylanhydroicaritin (**81**) indicate that the preanyl group, rather than the lavandulyl group, might make predominant contributions to BACE1 inhibition [68; 89].  
Rutin is the 3\({}^{\prime}\),4\({}^{\prime}\),5,7-tetrahydro-3-[\(\alpha\)-L-rhammopyranosyl-(1\(\rightarrow\)6)-\(\beta\)-D-glucopyranasyloxy] flavone (**83**), a glycosylated flavonol on C3 of several citrus fruits, which exhibits a BACE1 IC\({}_{50}\) of 0.004 uM [90], confirming the importance of the hydroxy groups at C4\({}^{\prime}\) and C5, as well as of a hydrophilic group at C3.  
Figure 8 shows the chemical structure of the flavonoids **76-83** that inhibit BACE1 with an IC\({}_{50}\) range of 0.004 to 22.48 uM.
# NOMA-Based VLC Systems: A Comprehensive Review
## 1 Introduction
### Background
#### 1.1.2 NOMA for RF
Most of the existing studies on RF-NOMA mainly address the issue of quality of service (QoS) requirements [22; 23], while only a few focus on improving the energy efficiency of RF-NOMA [21]. In [20], the authors introduced a distance-dependent PA (DDPA) method for a NOMA system for mMIMO, carried our performance analysis, and compared it with static power allocation (SPA) methods which are commonly reported in the literature for RF-NOMA systems. They stated that SPA outperforms DDPA in the context of energy efficiency and overall sum rate. Even though VLC-NOMA systems are inherently more energy-efficient compared to RF-NOMA systems, their energy efficiency can be effectively enhanced by proper power allocation. Some recent works have also focused on enhancing the energy efficiency of RF-NOMA systems [15]. In Table 2, we have presented a comparison of different multiple access techniques for wireless cellular networks.
## 5 Detection in UWB Positioning Algorithms
### Performance of ML Algorithms  
As stated, signal features can be extracted and used for NLoS classification and mitigation. This sub-section presents the results obtained by applying ML-based algorithms, such as KNN-, SVM-, DT-, NB-, and NN-based UWB signal features. For this experiment, 1000 LoS and 100 NLoS UWB signals are used [17; 78]. The performance is compared with the running time, confusion matrix, and the correct rate (CR) for LoS and NLoS components. The findings are summarized in Table 5. The confusion matrix depicts metrics, true positive (TP), false positive (FP), false negative (FN), and true negative (TN), respectively. The best classification performance is achieved by the NN algorithm. TP = 983 refers to LoS, resulting in a correct rate of 98.3%, which means 17 samples out of 1000 samples were inaccurately classified. The average running time of NN is 0.0606 s, which is better than that of the other considered algorithms. The precision and recall can reach 98.9% and 98.3%, respectively, and the overall accuracy is 97.5%. Compared to NN, NB follows closely and has similar performance, while the rest of the algorithms reach a slightly lower running time, and their classification accuracy is also lower in the considered experiment.  
Figure 15 compares the receiver operating characteristics (ROC) curve and the area under the curve (AUC) of the discussed algorithms. The figure is plotted for the false positive rate (FPR) versus the true positive rate (TPR). The closer the curve to the upper left corner, the better the performance of the classifier. It is easily noticeable that the NN algorithm has the largest AUC of 0.984. Hence, it is superior to other algorithms and can classify the NLoS signals with the highest accuracy and, thus, improves the overall performance of the IPS.  
Figure 15: Receiver operating characteristics (ROC) and area under the curve (AUC) comparison of the state-of-the-art ML algorithms.  
\begin{table}
\begin{tabular}{l l l l l l l l l l l l} \hline \hline \multirow{2}{*}{**Algorithm**} & **Running** & **LoS** & **NLoS** & & & & & & & & \\  & **Time** & **CR** & **CR** & **TP** & **FN** & **FP** & **TN** & **Precision** & **Recall** & **Accuracy** \\ \hline k-NN & 0.0491 s & 97.5\% & 79\% & 975 & 25 & 21 & 79 & 97.9\% & 97.5\% & 95.8\% \\ SVM & 0.1166 s & 97.4\% & 87\% & 974 & 26 & 13 & 87 & 98.7\% & 97.4\% & 96.5\%
## 5 Performance Evaluation  
To evaluate the performance of CB-tree, we implemented CB-tree and various flash-aware B-trees on Flash SSD environments. For measuring the effect of memory buffer, CB-tree was experimented with the original B-tree without any buffer as a base algorithm, Lazy update B+-tree (LU-tree), IBSF, and AS-tree using the same sized write buffer. Also, for assessing the performance of structure-modified B-trees, Wandering-tree as a base algorithm, u*-tree, dIPL B+-tree, and LSB-tree were implemented. Every node in each tree consisted of 128 entries that contain a key to find a child node and a pointer to the child node. For the comparison, we measured the number of flash operations, creation time, and retrieval time.  
The experiments for buffered B-trees are performed on SAMSUNG S470 64 GB MLC SSD (Figure 11(a)) running in Linux kernel 2.6 with Intel Core i5-2550 CPU and 8 GB DDR3 memory. The experiments for structure-modified B-trees are performed on OpenSSD platform (Figure 11(b)) [47] that can modify its internal mapping algorithm. OpenSSD platform contains the ARM7 TDMI-S core, 64 MB mobile SDRAM, and two 32 GB SAMSUNG K9 LCG08U1M MLC NAND modules.  
Table 4 shows I/O performance of the flash SSD environment used in our experiments. As depicted in this table, the performance of the SSD product is faster than that of the OpenSSD platform because most SSD products employ parallel writing and an internal buffer for the performance improvement. In contrast, OpenSSD platform simply offers to apply custom mapping, indexing, and caching algorithm for measuring the performance of the flash SSD. Therefore, we used MLC SSD for measuring the realistic performance of buffer-based B-trees. We also used OpenSSD platforms for measuring the performance of structure-modified B-trees because we can manipulate the physical address for implementing structure-modified B-trees.  
Figure 11: Flash storage devices.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Categories** & **B-Tree** & **CB-Tree** \\ \hline the cost of the search operation & \(R_{B}=C_{R}H\) & \(R_{c}=C_{R}(H-1)\) \\ \hline the cost of the insert operation & \(W_{B}=C_{R}H+C_{W}\) & \(W_{C}=(C_{R}+C_{W})\cdot(H-1)\) \\ \hline the total cost of the insert operations & \(T_{B}=n(C_{R}H+C_{W})\) & \(T_{C}=n/m\cdot C_{W}\) \\ (sequential data pattern) & & \\ \hline the total cost of the insert operations & \(T_{B}=n(C_{R}H+C_{W})+2n/m\cdot C_{W}H\) & \(T_{C}=n/m\cdot C_{W}H+nC_{W}\) \\ (node split pattern) & & \\ \hline \hline \end{tabular}
\end{table}
Table 3: Notation for evaluation of B-Tree and CB-Tree.
# An Iterative Optimization Algorithm for Planning Spacecraft Pathways Through Asteroids
###### Abstract  
In this article, we explore the use of meta-heuristic algorithms for costly black-box permutation optimization problems. These combinatorial problems are defined by solution spaces that consist of permutations of elements, with an objective function that lacks a closed mathematical representation and is expensive to evaluate. The focus of our investigation is the Asteroid Routing Problem (ARP), which seeks to determine the optimal sequence of asteroids to be visited by a spacecraft while minimizing energy consumption and travel time. Specifically, we assess the performance of a simple algorithm called FAT-RLS, which primarily relies on a randomized local search approach, enhanced with a tabu structure and a mechanism to adjust the perturbation strength. We conducted a series of experiments on well-established instances of the ARP to compare the effectiveness of FAT-RLS against two recognized meta-heuristics designed for this problem, namely, UMM and CEGO. Experiments were conducted in both uninformed and informed settings, where the meta-heuristics are initialized with a specifically designed constructive algorithm for the ARP. The results demonstrate that FAT-RLS is consistently superior to UMM, while there is no conclusive evidence for the comparison with CEGO, though the FAT-RLS results seem slightly better.  
combinatorial optimization; Asteroid Routing Problem; randomized local search Article