esa-sceva/satcom-chunk-collection huggingface dataset:
# Systems Engineering: Availability and Reliability
## 5 Systems Analysis, Simulation, Design and Modeling
This method may be used to produce a precision metrological scale on stainless steel tape. The generation process takes place in the dynamic mode because both the steel tape and the laser raster generation head are constantly moving during the process. The main aim of the research [15] was to develop a system for measuring the displacement of the tape in the raster generation device, to examine the model of that system and to evaluate the possible impact of external and internal factors on raster generation in the dynamic mode. The use of numerical methods for simulation, design or modeling, such as finite element analysis (FEA), has proven to be an advantageous tool to predict the mechanical behavior of many materials. Up to now, the application of FEA related to elastomers and other cork composites has been utilized to access static, dynamic loading and impact behavior. One of the first requirements for the application of isolation pads is to evaluate their capacity to support static loadings. Regarding elastomers, one of the crucial steps during FEA is the definition of material properties. Typically for large strains, elastomer's properties are defined through the application of non-linear models. However, if a linear stress-strain relationship at small strains is observed, Hooke's Law can be adopted for that strain range. As expressed by [PERSON] et al. [16], like other types of elastomers, different geometries of the same cork-rubber material present different mechanical behavior when subject to compression between bonded plates. To validate the application of Hooke's Law on cork-rubber materials, under compression at small strains, a set of experimental and numerical analyses has been conducted [16]. Using finite element analysis, a methodology is described to relate frictionless and frictional compression between a cork-rubber sample and loading plates. Based on that, the performance of square cross-section blocks with other dimensions can be evaluated. The results obtained by this approach [16] showed a good agreement with experimental compression tests and with outputs from other models available in the literature relating Young and apparent compression moduli. However, future research should address the effect of higher shape factors, other cross-section shapes (rectangular and other polygons), and the friction coefficient between sample and loading surfaces. Moreover, applying this knowledge and relating it to the dynamic compression behavior of isolation pads could be a topic of interest.
## Appendix B Forward Error Correction  
Before the data whitening step in DASH7, an optional Forward Error Correction (FEC) step can be applied. FEC is a channel encoding step that adds redundancy bits to the transmitted data using a predetermined algorithm, making the data more robust against bit errors. In the case of DASH7, the encoding process includes two stages.  
The first stage includes a 1/2 rate non-recursive convolutional encoding process with a constraint length (L) of 4. The 1/2 base coding rate indicates that each input bit will be encoded into two output bits. The encoder itself consists of three shift registers where an XOR operation is applied twice in a specific manner, eventually gaining two output bits.  
The second stage applies a 32-bit interleaving process executed on every 2-bit symbol. This interleave/deinterleave process scrambles and separates adjacent symbols, thus lowering the impact of bursty errors that mostly span multiple bits and can be induced by interference or time-varying signal strengths. In this way, the process increases the robustness against these errors [31]. In order to have a properly working interleaving process, a convolutional code trellis terminator is also appended to the unencoded data. This sequence is 0x0B0B for even-length byte inputs and 0x0B0B0B for odd-length byte inputs. In the DASH7 protocol, a 4x4 matrix interleaver is used.  
The bits coming from the convolutional coder are written into the rows of the matrix interleaver while the bits that will be sent are read from the columns of the matrix in a certain order. The interleaving operation is applied per 2-bit symbols. This means that the data are scrambled per 32 aligned bits. Note that FEC is only applied when using Coding Scheme 2 of DASH7, where the data are firstly FEC-encoded and afterwards PN9-encoded. Figure A1 depicts the operation of the encoder stage and interleaving stage. The following example is based on [32], whereas Figures A2 and A3 show the filled buffers of the interleaver. The output bytes are highlighted in bold.
## 7 Conclusions  
The paper suggests an alternative approach that is effective in describing the dynamical regimes for different types of traps in a coherent manner. The results obtained bring new contributions towards a better understanding of the dynamical stability (electrodynamics)of charged particles in a combinational ion trap (Paul and Penning), using both electrostatic DC and RF fields over which a constant static magnetic field is superimposed. One of the advantages of our model lies in better characterizing ion dynamics for coupled two ion systems and for many body systems consisting of large number of ions. It also enables identifying stable solutions of motion and discussing the important issue of the critical points of the system, where the equilibrium configurations occur.  
Applications span areas of vivid interest such as stable confinement of antimatter and fundamental physics with antihydrogen [2; 52] or high precision measurements (including matter and antimatter tests of the Standard Model) [9; 54]. Better characterization of ion dynamics in such traps would lead to longer trapping times, which is an issue of outmost importance. Other possible applications are Coulomb or ion crystals (multi body dynamics). The results and methods used are appropriate for the ion trap physics community to compare regimes without having the details of the trap itself.  
Conceptualization, B.M.M.; methodology, B.M.M. and S.L.; software, S.L.; validation, B.M.M. and S.L.; formal analysis, B.M.M.; investigation, B.M.M. and S.L.; resources, B.M.M. and S.L.; writing--original draft preparation, B.M.M.; writing--review and editing, B.M.M. and S.L.; visualization, S.L. and B.M.M.; project administration, B.M.M. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the Romanian Space Agency (ROSA)--contract number 136/2017 and by Ministerul Cercetarii si Inovarii--contract number 16N/2019.  
Not applicable.  
The data that supports the results of this study are available within the article.  
B.M.M. is grateful to [PERSON] for fruitful discussions and suggestions made before submitting the manuscript. B.M.M. and S.L. would like to thank the anonymous reviewers for the valuable suggestions and comments on the manuscript.  
The authors declare no conflict of interest.  
The following abbreviations are used in this manuscript:  
3D 3 Dimensional  
CM  Centre of Mass  
LT  Linear Ion Trap  
QED  Quantum Electrodynamics  
QIP  Quantum Information Processing  
QIT  Quadrupole Ion Trap  
RF  Radiofrequency  
SCCS  Strongly Coupled Coulomb Systems  
SET  Surface Electrode Trap
# Enhancing Energy Efficiency in IoT-NDN via Parameter Optimization
## 6 Evaluation
### Results of the Simulation
#### 6.2.5 Caching Strategy  
The _caching strategy_ has a smaller impact on the ranking than caching schemes but a more considerable impact than forwarding strategies. Again, the effect of this variable parameter mostly depends on the specific sequence.  
Figure 5: Two examples for the caching scheme: (**a**) shows the probabilities for the repetitive scheme, grid topology and size 64. (**b**) demonstrates the total energy difference between schemes: The consumed energy per node on average for probabilistic 50% is 287.12 J, while for no caching the consumed energy is 287.38 J.  
Independently of the graph topology and size, LFU and LRFU are the best caching strategies for **INCREMENTAL**. This effect is stronger for topologies with shorter paths, i.e., stars and complete graphs: For the former, the rank deviation is up to 30, and for complete graphs up to 25. LFU and LRFU have a deviation of approx. 15 for the other topologies. On the other hand, LRU is consistently below average. This is because LRU always evicts the element that has not been requested for the longest time. Since the number of requested packets is much bigger than the Content Store size, LRU always causes a cache miss. LFU and LRFU are likely to cause many cache misses, too, but every element has the same frequency of 1 when it first enters the CS. Depending on the decision of the priority queue of LFU and LRFU, every element can possibly be evicted. Hence, it is possible that when the sequence repeats, some of the CS elements are found again.  
For **REPETITIVE**, only one policy stands out in particular: the random strategy. It is consistently the worst policy across all topologies and sizes. The difference in rank to the next worst strategy is often approx. 10. Among the other strategies, no clear pattern can be recognized. The fact that the random policy is consistently the worst seems rather surprising.  
For **SIMPLE_RANDOM**, LRU and PRIORITY_FIFO are the best-performing strategies. Their rank deviation is usually between 5 and 10. Meanwhile, the rank deviation for FWF, the worst policy in this scenario for most topologies, ranges from \(-5\) to \(-15\). This is also illustrated in Figure 6. SIMPLE_RANDOM generates many unique packets and therefore a lot of diversity. Hence, it makes little sense to flush the entire cache when it is full since that removes a lot of helpful information from the CS, making FWF undesirable.  
**LINEAR_RANDOM** displays very similar behavior as SIMPLE_RANDOM: Again, LRU and PRIORITY_FIFO are superior to all the other caching strategies with a rank deviation of approx. 10, whereas FWF is the worst. Structurally, SIMPLE_RANDOM and LINEAR_RANDOM are very similar, so this observation is logical.
# Efficient Mobile Sink Routing in Wireless Sensor Networks Using Bipartite Graphs
## 2 Bipartite Graph Overview  
Nowadays, W.S.N.s are playing a major role in numerous applications, including military, environment, and disaster monitoring applications, to name but a few. Consequently, it is very important to consume sensor nodes wisely with limited resources to better control the phenomenon being studied and prolong the network lifetime [9]. According to [10], a bipartite graph is considered a simple graph where the vertices of a graph are divided into two disjoint sets. In other words, consider a graph denoted by G and the vertices of G denoted by V (G). A bipartite graph is constructed by dividing the vertices of G into two disjoint sets, namely, V\({}_{1}\) and V\({}_{2}\), with the following properties:  
* Consider a vertex \(v\) where \(\in\) V\({}_{1}\), and then \(v\) cannot be adjacent to vertices in V\({}_{1}\). On the contrary, it can be adjacent to vertices that belong to V\({}_{2}\).
* Consider a vertex \(v\) where \(v\in\) V\({}_{2}\), and then \(v\) cannot be adjacent to vertices in V\({}_{2}\). On the contrary, it can be adjacent to vertices that belong to V\({}_{1}\).
* \(V_{1}\cap V_{2}=\emptyset\), there is no intersection between V\({}_{1}\) and V\({}_{2}\).
* \(V_{1}\cup V_{2}=V(G)\), the union of V\({}_{1}\) and V\({}_{2}\) will result in all the vertices of the graph G.  
As a result, when creating a bipartite graph for a randomly deployed W.S.N., sensor nodes will be divided into two sets. Hence, deploying a mobile sink to move and collect data from one set is possible. After that, when finishing all the nodes in the set, the mobile sink will move and start collecting data from the other set. The nodes in one set are also adjacent to nodes in the other set, which can benefit the mobile sink when gathering data from static nodes.  
For example, the graph in Figure 1a represents 5 nodes labeled by numbers from 1 to 5. To check whether the given graph is bipartite, we need to apply the definition of a bipartite graph. In other words, we need to check if the nodes in the given graph can be partitioned into two disjoint sets, V\({}_{1}\) and V\({}_{2}\), with the abovementioned properties.  
Figure 1b shows that the nodes or vertices of the graph shown in Figure 1a can be divided into two disjoint sets denoted by V\({}_{1}\) and V\({}_{2}\) in the figure. Furthermore, it can be seen that the nodes that are part of the set named V\({}_{1}\) are not neighbors or adjacent to each other. However, each node  
in each set are not neighbors or adjacent. Still, at the same time, every node in one set is adjacent to nodes in the other set.  
Thus, using a bipartite graph can improve the performance of the W.S.N. in two ways: (1). The mobile sink will visit smaller nodes, i.e., not all the nodes in the network in each round. (2). The proposed model will help stationary sensor nodes mix between multi-hop and single-hop communication, depending on which set is being visited and to which set the stationary sensor node belongs.
## 6 Opportunities for Out-of-Sight Damage Detection
In order to detect other defects, other frequencies have to be evaluated. For instance at 90 kHz, the delamination at the left is detected as shown by Figure 9.  
Figure 9: Detection of out-of-sight side-damage by using the second harmonic component measured at two small areas: (**a**) second harmonic amplitude map at 90 kHz with indication of the measurement areas, (**b,c**) wavenumber maps corresponding to the second harmonic component at 90 kHz with indication of the direction of the incoming wavefield.
# Regional Crop Gross Primary Productivity and Yield Estimation Using Fused Landsat-MODIS Data
## 4 Discussion
Promising areas for model improvement include the use of additional satellite observations to construct more accurate estimates of key vegetation parameters and drivers [60] and the use of high temporal frequency estimates of crop yield at key decision points during the growing season to determine the projected value of alternative decisions. More detailed cropland inventory data capable of resolving field and farm level heterogeneity may improve the delineation of HIGPP and yield variations for different crop conditions and consequently improve the utility of yield estimates. In situ monitoring of GPP from flux tower sites representing major MT crop types would provide an effective means to improve model calibration and performance. The results of this study and other ongoing efforts are being used to improve crop monitoring capabilities using global satellite observations to inform resource management and policy decisions and enhance national and global food security.
## 2 Problem Formulation  
### Magnetorheological Damper Model  
A schematic illustration of an MR damper is shown in Figure 1. It is essential to count on an appropriate dynamic model to calculate the command current (or voltage) for the MR damper in order to ensure optimal suspension performance in line with the vehicle status.  
MR dampers exhibit significant hysteretic behavior when the velocity range of the damper is limited. However, for larger velocities, the force demonstrates a nearly linear variation with velocity. The hyperbolic tangent function is frequently used to model hysteretic behavior, as it effectively captures the nonlinear, memory-dependent characteristics typical of such systems. This function's smooth, S-shaped curve allows for accurate representation of gradual transitions, making it a valuable tool for simulat  
Figure 1: Common schematic of an MR damper.  
responses often observed in materials and control applications with hysteresis. Inspired by [39], the following equation is proposed for modeling the MR damper:  
\[\begin{split} F_{md}(t)&=(a_{0}+a_{1}i(t))\text{tanh} \bigg{(}a_{2}\bigg{(}\dot{z}_{def}(t)+\frac{V_{0}}{X_{0}}z_{def}(t)\bigg{)} \bigg{)}\\ &\quad+a_{3}\bigg{(}\dot{z}_{def}(t)+\frac{V_{0}}{X_{0}}z_{def}(t) \bigg{)}\end{split} \tag{1}\]  
where \(F_{md}\) is the MR damper force. \(a_{i}\), \(i\in 0,\dots,3\), are experimental parameters to be adjusted. The damper deflection is denoted by \(z_{def}\). The ratio \(V_{0}/X_{0}\) depends on the absolute values of the hysteretical critical velocity \(V_{0}\) and hysteretical critical displacement \(X_{0}\), respectively (see Figure 2). These denote the piston velocity and displacement when \(F_{md}=0\). The stiffness (\(k_{mr}\)) and damping (\(c_{mr}\)) parameters of the MR damper are defined by  
\[\begin{split} k_{mr}&=a_{3}\frac{V_{0}}{X_{0}}\\ c_{mr}&=a_{3}\end{split} \tag{2}\]  
The employed MR model (1) is an extension of the Bingham model [22], which models the damper force as \(F_{md}=c_{1}sgn(\dot{z}_{def})+c_{2}\dot{z}_{def}\). It is crucial to acknowledge that the Bingham model does not incorporate the elastic characteristics of the damper. Additionally, the employed model utilizes the tanh function, which has a more gradual behavior than the sgn function for analyzing the damper hysteresis. It is worth noting that the Bingham model is a specific instance of the proposed model, when the hysteresis, pre-yield, and current effects on the damper are neglected.  
In contrast to the bi-viscous hysteresis model [20], which employs a six-section piecewise function incorporating three parameters to model the MR damper behavior, the proposed method offers a straightforward solution for analyzing the dynamic behavior of MR dampers, as only one function is required.  
In this work, the parameters of the model (1) were obtained through experimentation. The experimental setup and tests are presented in Section 3.1.
# Experimental Investigation of Crystal Blocking in Drainage Pipes for Tunnels in the Kast Region
## 1 Introduction
[PERSON] found that the flocking drainage pipe has an anti-crystallization effect, and the efficiency of the flocking drainage pipe can increase by more than 50% compared with that of ordinary drainage pipes [25, 26, 27, 28]. The aforementioned literature research recognized that the main substance of the crystallization blockage of tunnel drainage pipes is carbonate. However, there has been little research on the crystallization development law of circular drainage pipes and longitudinal drainage pipes in combination with the layout characteristics of tunnel drainage pipes. Therefore, this work presents a series of experiment-based studies of the drainage system subjected to crystal blockage under the actual tunnel drainage system layout environment. In order to study the law of crystal clogging in tunnel drainage pipes, an experimental equipment installation consisting of a drainage system, a water supply system, and a test chamber is established. Consequently, the influences of the connection method of the drainage pipe, the pipe diameter, the distance between the circular drainage pipes, and the material of the drainage pipe on the crystallization law are investigated. (The factors that have less influence on the blockage of the tunnel drain crystal are not considered in this paper). It is found in the present work that the main blocking substance of the tunnel drainage system is calcite, and its formation is related to the ion concentration of the groundwater, the height of the groundwater level, and the temperature. Some useful suggestions are also proposed for preliminary design purposes.
## 2 Potential Applications of Aeroacoustic Metamaterials
### Absorption and Dissipation
The corrugated structure exhibited several resonant frequencies that caused the air in the perforation to oscillate severely when excited, thus dissipating energy in the viscous boundary layer, obtaining a broadband high absorption coefficient for a wide range of incident angles of acoustic perturbation. Figure 4: The original “optimal” absorbing metamaterial obtained by [PERSON] et al. The unit cell is composed of 16 resonant channels differing in length and folded to compact the sample (image from [47]). Figure 3: Various metamaterial designs for low-frequency absorption: (**a**) a membrane decorated with added platelets and displacement related to the first three eigenfrequencies of the structure from [47]; (**b**) a dual resonant metamaterial composed of [PERSON]’s resonators, and a perforated sheet adopted as an innovative liner in [43]; (**c,d**) two different space-coiling designs, respectively from [45] and [46]. The dissipation of acoustic energy is fundamental in each design. The annoyance from a noise, however, is not only related to its intensity. The mathematical description of an annoyance is not a simple task, due to the subjectivity of the sound event perception, which is affected by non-acoustical factors that have not yet fully been enlightened and are still an object of study. Projects like SEFA (Sound Engineering for Aircraft) and COSMA (Community Oriented Solutions to Minimise aircraft noise Annoyance) have demonstrated that the spectral content of the signal is fundamental in defining its effect on listeners. Extensive psychometric test campaigns performed during the projects were able to identify _weakly-annoying_ target sounds that were usually characterized by attenuated tonal components drawn in broadband noise. This illustrates how important it is to enhance the acoustic absorption at specific frequencies to improve the quality of sound/noise from an aircraft and hence, its acceptability by the community, i.e., reducing acoustic pollution, even while maintaining the sound level. Such devices would enable the possibility of engineering the noise signature from an aircraft and hence, rethinking the conceptual design procedure by including the \"desired noise\" as a variable to optimize [49; 50; 51].