esa-sceva/satcom-chunk-collection huggingface dataset:
## 6 Experimental Results and Discussion
### Experimental Damage Observations and Crack Patterns
#### 6.1.2 Specim S1B  
Photographs of the crack patterns and CFRP fabric damage for S1B at the end-yielding region are provided in Figure 11. The first hairline vertical crack in the CFRP next to the support initiated at 0.4% drift while loading upward from the U-wrap corner (i.e., beam  
Figure 10: Crack patterns within the end-yielding region for specimen S1A at: (**a**) 1.5% drift, (**b**) 2.0% drift, (**c**) 3.0% drift, (**d**) 4.0% drift, (**e**) 6% drift.  
softfit) and largened slowly during higher drift levels. However, no cracks developed from the anchored tips of the U-wrap until reaching a downward-loading drift of 1.1% (Figure 11a). This occurred two displacement levels later (i.e., six additional cycles) than the unanchored CFRP U-wrap on S1A. The delayed debonding of the FRP U-wrap ends is attributed to the presence of the embedded GFRP anchors. It is important to note that anchorage is not expected to prevent debonding of the FRP laminate. Local debonding at locations where shear cracks cross the FRP laminate still needs to occur to effectively engage the FRP system. However, anchorage allows for the FRP laminate to carry load after debonding has occurred and develop higher strains. First yield of the longitudinal reinforcement next to the support was detected at 0.4% drift, earlier than for S1A. From this point on, despite the anchorage, cracking and failure development for S1B progressed similarly to that of S1A. The crack starting at the tip of the U-wrap underneath the slab at 1.1% drift extended downward during successive cycles to form a full-depth vertical tear at the location of the dominant flexural-shear concrete crack, at about 15 cm (6 in) from the support, which widened through the 1.6% and 2.3% drift cycles (Figure 11b). Sometime between the second and third cycles at 3.3% drift, the GFRP anchors located at the teared section of the wrap pulled out, and similarly to S1A, a strip of the CFRP wrap completely detached (Figure 11c). Again, the detachment of one strip was followed by the abrupt fracture of the adjacent strip of CFRP at one of the beam's web corners during the first cycle at 4.5% drift while loading down (Figure 11d). Hinge deterioration progressed very quickly from this point on. In comparison to S1A, peak capacity was similarly achieved during the initial cycle at 3.3% drift for 5B. However, the strength loss accumulated during the three cycles at 3.3% drift before the fracture of the second strip was higher for 5B (15% downward) compared to 5A (4%). Fracture of the CFRP resulted in an additional 23% strength loss in the downward direction and accumulated during the two cycles at 4.5%. Further hinge deterioration during the cycles at 6% occurred similarly to 5A.  
Figure 11: Crack patterns within the end-yielding region for specimen S1B at: **(a)** 1.1% drift, **(b)** 2.3% drift, **(c)** 3.30% drift, **(d)** 4.5% drift.
## V\(\mathbf{{}_{oc}}\) Loss Due to Front Surface Metallization  
### Laser Doping  
The n type front surface is patterned by laser doping, which introduces locally heavy doping within openings. However, laser doping inevitably introduces damage to the surface and bulk of the silicon solar cell. Laser damage can be partially healed by subsequent annealing. The \(V_{oc}\) loss depends on the power, speed and wavelength of the laser, the structure of the solar cell and the subsequent annealing temperature. A minimum \(V_{oc}\) loss of 6.1 mV has been reported [16]. Figure 6 illustrates this laser doping process on a test sample made of epi on FZ wafer, whose front surface was shallowly textured and passivated by SiO\({}_{x}\)N\({}_{y}\). Based on our experiments, the \(V_{oc}\) loss at this laser doping step can be 10-20 mV, and Figure 7 shows the \(iV_{oc}\) changes on a test sample in this process.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Steps** & \multicolumn{2}{c}{**Front SiO\({}_{x}\)N\({}_{y}\)/Rear SiO\({}_{2}\)**} & **Rear metallization** \\ \hline \multirow{2}{*}{**Values**} & Lifetime (\(\mu\)s) & \(iV_{oc}\) (mV) & \(V_{oc}\) (mV) \\  & 445.2 & 685.4 & 665–673 \\ \hline \hline \end{tabular}
\end{table}
Table 7: Lifetime, \(iV_{oc}\) and \(V_{oc}\) change of test structures before and after rear surface metallization.  
Figure 5: Test sample before rear contact patterning (**left**), PERC rear contact with Al metallization (**right**).
## 4 Analysis
### Cellular Automata Model for Dar es Salaam Port Traffic Flow
#### 4.2.2 Setting Up the Cellular Automata Model for Dar es Salaam Port  
Cellular automata (CA)-based simulation framework is applied to model the traffic flow. We will model traffic using the Nagel-Schreckenberg (NaSch) model, adjusting it to reflect the challenges faced by African ports and roads. This model will simulate traffic over a 20 km stretch leading from Dar es Salaam Port to the primary highway network.  
Step 1: Initialization  
* Road network: A 20 km stretch is divided into 2670 cells (each 7.5 m long). The first 10 km is a 2-lane highway, while the remaining 10 km features construction zones that reduce capacity to a single lane.
* Vehicle mix: The traffic consists of 60% heavy trucks and 40% smaller trucks and passenger vehicles.
* Initial vehicle density: The road starts with 900 vehicles distributed randomly across the network.  
Step 2: NaSch model rules with Dar es Salaam Port context  
Acceleration:  
Each vehicle attempts to accelerate by 1 cell per time step, up to its maximum speed  
\[v_{n}\;(t+1)=min(v_{n}\;(t)+1,v_{max}\;)\]  
where  
\(v_{n}(t)\)-is the speed of vehicle \(n\) at time t.  
\(v_{max}\)-is the vehicle's maximum speed (in cells per time step).  
The acceleration rule is given by the following: Heavy trucks accelerate slower due to rough road conditions, potholes, and cargo weight. For heavy trucks with a max speed of 60 km/h (8 cells per time step), their acceleration rule is modified:  
\[v_{truck}\;(t+1)=min(v_{truck}\;(t)+1,8\;cells)\]  
For smaller trucks and cars: For passenger cars and smaller trucks with a max speed of 80-100 km/h (12-14 cells per time step):  
\[v_{truck}\;(t+1)=min(v_{truck}\;(t)+1,14\;cells)\]  
Deceleration: Given the high traffic density and poor road conditions, vehicles often decelerate more sharply to avoid potholes or navigate around traffic jams:  
If the gap between vehicle \(n\) and the vehicle ahead n + 1 is smaller than \(v_{n}(t)\), the vehicle decelerates to avoid a collision:  
\[v_{n}\;(t+1)=min(v_{n}\;(t),g_{n}\;(t))\]  
where:  
\(g_{n}\;(t)\)--is the number of empty cells between vehicle \(n\) and the vehicle ahead.  
Random Slowdown:  
With a certain probability \(p\), the vehicle slows down by \(1\) cell to simulate human behavior or environmental disruptions (e.g., potholes, poor visibility). This slowdown reflects random variations in driving behavior:  
\[v_{n}\;(t+1)=max(v_{n}\;(t)-1,0)\]  
_with probability \(p\)_  
For this simulation, we use:  
Dry season: \(p\) = 0.3  
Rainy season: \(p\) = 0.5 (reflecting worse road conditions and caution due to rain).  
Lane Changing:  
Vehicles change lanes to avoid slower traffic if there is a sufficient gap in the adjacent lane:  
\[Change\;lane\;if\;g_{adjacent}\;>5\;cells\;ahead,\;and\;2\;cells\;behind\]  
Movement:Each vehicle moves forward based on its updated speed:  
\[x_{n}\;(t+1)=x_{n}\;(t)+v_{n}\;(t+1)\]  
where  
\(x_{n}\;(t)\)--is the position of vehicle \(n\) at time \(t\).
# The Development of Key Technologies in Applications of Vessels Connected to the Internet
## 5 Challenges and Prospects
### Prospects of the IoV System  
With the development of the IoV, it will study more advanced ship intelligent terminals and buoy intelligent terminals to enrich the means of perception. The integration of these communication technologies such as 3G, 4G, AIS and RFID will realize intelligent switching between one another. The data information collected from the sensors will be more compatible. The integration information platform of the IoV system with the ship-shore interaction will be more comprehensive and advanced.  
In future, a variety of novel heterogeneous networks will be applied in the IoV system. Meanwhile, the IoV system will realize the networks switching seamlessly to increase efficiency and reduce the operating costs.
# Thermal Failure Propagation in Lithium-Ion Battery Modules with Various Shapes
## 1 Introduction
examined the failure propagation behaviors of small modules of cylindrical and stacked pouch cells after thermal runaway was induced in a single cell. Cylindrical cells were observed to be less prone to propagate compared to the pouch cells, owing to the limited contact between neighboring cells. [PERSON] et al. presented a numerical model to analyze the heat propagation in a custom-made battery module. It was found that a combination of small insulating layers wrapped around the cells and a conductive heat sink was beneficial to design a safer battery module which could mitigate the thermal runaway propagation. However, many accidents of LIBs take place when they are in the state of usage, such as EVs catching fire when they are running and laptops catching fire during use. But little research has been done to investigate the thermal failure propagation of battery modules under discharging condition, and differences between modules with or without discharging have not been a concern. In addition, battery modules are generally arranged in various shapes according to the application scenarios, while the characteristics of thermal failure propagation in modules with different shapes still lack examination. Thus, this paper conducted an experimental study on the thermal failure propagation in battery modules, intended for revealing the effects of discharging and module shape on the failure propagation. Specific information, including experimental photograph, battery surface temperature, thermal runaway time, propagation speed, and mass loss, was measured and analyzed to provide necessary basic data for the thermal failure propagation issues of battery modules.
# Real-Time Location-Positioning Technologies for Managing Cart Operations at a Distribution Facility
## 4 Case Study: Tracking of Carts in a Large and High-Traffic RFID-Enabled Air Mail Centre
### Offline RFID Data Analytics  
While this platform is still in use at AMC, we only extracted data captured between January 2015 and April 2015 for the analysis in this study. Every second, the real-time information about the cart locations was transferred to the information system via the wireless data transmissions between the tags and readers. To reduce the data storage requirement and the computational effort for data analysis, we discarded records that a same cart staying at the same position for a period of time; in other words, we only kept those indicating moving activities. In total, we obtained 11,287,904 records and all are used in this analysis. Each data record consists of a unique record ID, the timestamp of the record created, the location of the cart (expressed in terms of the x- and y- coordinates of the cart on the layout map), the reader ID and the tag ID.  
Data visualization is adopted as the data analytics technique to analyze the cart staging operations. The AMC staff can visualize the collected offline RFID data to analyze the cart movements, observed non-trivial operational issues and improve operations. The staging duration was measured as the sum of time periods where the cart was inactive. The speed of a cart was defined as the distance moved divided by the time. The number of movements was defined as the time points which the status of the cart changed from inactive to active.
# Impact of CoAP and MQTT on NB-IoT System Performance +
## 4 Discussion  
In this work, we studied 5G massive IoT realization over a NB-IoT system. The simulation study performed confirms the working hypotheses that MQTT as a TCP based system impacts negatively both the device perceived throughput and the system load as well as service availability and coverage. When confirmation of sensor report transmission is required, CoAP confirm provides a lightweight and cheap alternative to TCP. In fact, adding reliability to the transport layer in terms of TCP causes a lower service availability than using a simple UDP transport as the increased load caused by the protocol overhead saturates the system sooner.  
Figure 4: Lowest reachable path gain.  
Figure 3: Percentage of non-served devices as a function of load.  
Additional overhead from TCP retransmissions also impacts service coverage negatively. However, in this case, it seems that the additional overhead from CoAP confirm helps to reach devices in deep coverage better compared to no retransmission mode.  
Conceptualization, A.L.; Methodology, A.L.; Software, J.S., A.R. and A.L.; Validation, J.S., A.R. and A.L.; Formal Analysis, J.S., A.R. and A.L.; Investigation, J.S. and A.R.; Resources, J.S.; Data Curation, J.S. and A.R.; Writing-Original Draft Preparation, A.L.; Writing-Review & Editing, A.L. and A.R.; Visualization, A.R.; Supervision, A.L.; Project Administration, A.L. Funding Acquisition, A.L.  
This research has been partly funded by Business Finland as part of the TAKE-5 project in the 5 THGEAR programme, see [http://5 qfn.fi/projects/take-5/](http://5 qfn.fi/projects/take-5/).  
The authors declare no conflict of interest.
# Effect of Heat Treatment on Water Absorption of Chinese fir Using TD-NMR
## 2 Materials and Methods  
### Sample Preparation and Heat Treatment Process  
In this study, a 4 m long log was cut at breast height from a freshly filled 20 year old Chinese fir (_Cunningham Lancolata_ [Lamb.] Hook.) from a forest in Kaihua, China. The log was first cut off into eight 500-mm-long sections after air drying. Then 8 sticks with a cross section dimension of 15 \(\times\) 15 mm\({}^{2}\) were sawn from the 6-8 annual rings of each section, as shown in Figure 1. Finally, each stick was cut into three parts with dimensions of 150 \(\times\) 15 \(\times\) 15 mm\({}^{3}\) (longitudinal \(\times\) radial \(\times\) tangential, L \(\times\) R \(\times\) T), and 115 defect-free wood specimens in total were chosen to conduct the experiment. These specimens were randomly divided into 5 groups. There were 15 specimens for the control group and 25 for the other 4 groups for heat treatment. The heat treatments proceed at four different temperatures (160, 180, 200 and 220 \({}^{\circ}\)C) for 2 h in airtight equipment, and the inside atmosphere controls within comprising no more than 2 percent oxygen content. The MC of the pre-treated specimens was 9.8-12.5%, and decreased to 3.7-7.6% after the heat treatment.  
In order to pick out the specimens to undergo time domain nuclear magnetic resonance (TD-NMR) detection, samples with dimensions of 10 \(\times\) 15 \(\times\) 15 mm\({}^{3}\) (L \(\times\) R \(\times\) T) were cut in the middle of the 115 specimens; the two tangential sections and two radial sections of the samples were sealed by epoxy resin to make the water uptake only occur through the cross sections when immerse in distilled water. The samples were oven-dried at 103 \({}^{\circ}\)C until reaching a constant mass and weighed before and after they were sealed. Thereafter, samples were immersed in distilled water and weighed at pre-setting intervals to obtain the MC change. The average MC change of each group could be found by means of statistical analysis. Samples whose MC changes were close to the average MC of its group were chosen to conduct the TD-NMR experiment.
## 3 Related Works  
### Data Transmission  
UWSNs using acoustic signals have limited bandwidth and long propagation delays. There have been many studies to improve the reliability of data transmission under these conditions. The Reliable Routing and Application-based Scheduling protocol (RRAS) [12], which is a priority scheduling approach for multihop topologies, tries to balance between reliability and efficiency at the Media Access Control (MAC) layer. To achieve this goal, it utilizes the NACK-retransmission mechanism that delays the request of lost packets for an additional retransmission period. It divides time lots by the data transmission period and the retransmission period to reduce control frame handshaking and improve the throughput.  
In [13], Multiple-path Forward Error Correction (M-FEC) reinforces the existing Multi-Path Communication (MPC) in terms of reliability and energy efficiency. In previous MPC scenarios, receivers requested the retransmission of the lost packet whenever the original packet was damaged. However, error detection and packet reassemble were only done by the destination node in M-FEC. M-FEC is more efficient than MPC because retransmission can be eliminated in the intermediate nodes.  
Segmented Data Reliable Transfer (SDRT) based on a hybrid Automatic Repeat Request (ARQ) and FEC approach was proposed in [14]. ARQ requires the transmitter to resend the packet in which the error has been detected. FEC uses special codes that allow the receiver to detect and correct a limited number of errors. This hybrid mechanism supports quick encoding and decoding algorithm called Simple Variant of Tornado (SVT) codes to improve the reliability more than the pure ARQ.  
These approaches focused on the reliability of data transmission in the physical or the data link layer. They tried to maintain stable communications which is a base condition to collect sensing data. However, it is hard to verify the performance of these MAC-based schemes in practical applications and this causes compatibility problems. If sensor platforms use different MAC-based schemes, they  
Figure 5: UWSN architecture.  
cannot communicate with each other. Our approach is easy to implement, because the proposed scheme is applied to the application layer.
# An Iterative Guidance and Navigation Algorithm for Orbit Rendezvous of Cooperating CubeSats
## 5 Conclusions  
This paper has presented a guidance and navigation scheme for the rendezvous of two CubeSats. Autonomous sensing and maneuvering capabilities are becoming a requirement of many space missions, even when small satellites are employed. Therefore, it is very important to investigate algorithms that can provide the necessary GNC capabilities and to test them together in simulation so that they can be validated.  
The guidance law developed for this work is an iterative algorithm that calculates a discrete firing command \(\Delta v_{1}\) at a specific sampling time, based on the linear rendezvous theory and the HCW equations. The necessary information for the guidance law is derived from the navigation solution, which is based on a UF that processes the available on-board measurements (range and bearing).  
This scheme was tested in a 3-DOF simulation in both the nominal case (perfect information) and against a Monte Carlo campaign (incomplete information), assuming values compatible with CubeSat systems and applications. The Monte Carlo simulation allows us to take into account the variations in the measurement noise and the initial guess on the target's orbit. The results show that the obtained miss distance between the two spacecraft is below 1 m, a value suitable for the start of the docking operations.  
Further work on this topic should include a trade-off study of the proposed solution against different sampling and firing times. Furthermore, the 3-DOF model should be improved to account for the main orbital perturbations, such as the Earth's oblateness and the aerodynamic drag.  
All authors contributed equally to this work. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Not applicable.  
The authors declare no conflict of interest.  
Figure 4: Miss distance cumulative distribution obtained in the simulation campaign.
## 2 Working Principle  
For elements with mirror symmetry, the electromagnetic properties can be expressed using two diagonal Jones matrices.  
\[R(x,y)=\begin{pmatrix}r_{xx,f1}(x,y)&0\\ 0&r_{yy,f2}(x,y)\end{pmatrix} \tag{1}\]  
\[T(x,y)=\begin{pmatrix}t_{xx,f2}(x,y)&0\\ 0&t_{yy,f1}(x,y)\end{pmatrix} \tag{2}\]  
Here, the transmission and reflection coefficients and two principal axes x and y are represented by \(t_{xx}\), \(t_{yy}\), \(r_{xx}\), and \(r_{yy}\), respectively. In an ideal lossless system, \(|r_{xx}|+|t_{xx}|=1\) and \(|r_{yy}|+|t_{yy}|=1\) because of the energy conservation for efficient transmission \(|t_{xx}|=|t_{yy}|=1\); meanwhile, the reflection is considered zero. Similarly, for complete reflection \(|r_{xx}|=|r_{yy}|=1\), and the transmission will be zero. Transmitted and reflected waves must be manipulated together to have switchable phenomena in the dual bands. For this, Jones matrices must satisfy the following conditions [30].  
\[|t_{xx,f1}|=|r_{yy,f1}|\xi|t_{yy,f2}|=|r_{xx,f2}| \tag{3}\]  
The equation demonstrates that the metasurface exhibits an intriguing duality in its response to incident electromagnetic waves. Specifically, at the \(f1\) frequency band, the metasurface manifests itself as a transparent medium for waves polarized in the x-direction, while adeptly functioning as a reflector for waves polarized in the y-direction. Subsequently, within the \(f2\) frequency band, the metasurface assumes a contrasting behavior, reflecting x-polarized waves comprehensively, and transparently accommodating y-polarized waves. Both operational bands must have the capacity for agile tuning, according to the structure. Remarkably, by aligning the tuning of these frequency bands to achieve a state of harmonious overlap, characterized by efficient transmission and reflection attributes, the metasurface can seamlessly transition between the distinctive operational behaviorsof these bands. A visual depiction of this innovative concept is presented in Figure 1, providing a schematic illustration of the proposed methodology. TRA metasurface for transmission and reflection depends on the polarization of the incidence waves.
## 4 Discussion
### Implications for Rehabilitation  
The results of this study have several practical implications. The benefits of natural auditory stimuli, such as nature sounds, in improving postural balance suggest that they could be a valuable addition to rehabilitation settings. For example, nature sounds could be incorporated into therapeutic environments during balance exercises to promote relaxation and reduce stress-induced postural instability. This approach might be especially beneficial in situations where visual input is limited or unavailable, such as during vestibular rehabilitation exercises with eyes closed. The study also highlights the negative effects of noise on postural balance, particularly on unstable surfaces. This underscores the importance of creating controlled auditory environments during therapy. Reducing exposure to distracting sounds may help individuals with intellectual disabilities better focus on motor tasks and enhance their sensory integration. Moreover, the positive impact of nature sounds on cognitive performance, especially in dual-task activities like verbal fluency, suggests their potential use in cognitive-motor training programs. Clinicians could design interventions that combine verbal tasks with balance training while playing calming auditory stimuli in the background. This could improve both cognitive and motor skills simultaneously, which would be beneficial for daily activities that require multitasking. Rehabilitation strategies should also consider auditory environments to individual sensory profiles. For those who are particularly sensitive to noise, therapy sessions in quieter, controlled spaces with nature sounds could lead to better outcomes.  
Our findings are especially relevant for educational and therapeutic settings that work with individuals with intellectual disabilities. Integrating specific auditory stimuli into structured programs could be a cost-effective and accessible way to improve both postural and cognitive outcomes, ultimately enhancing functional independence and quality of life.