esa-sceva/satcom-chunk-collection huggingface dataset:
# System Design and Reliability Improvement of Wireless Sensor Network in Plant Factory Scenario
###### Abstract  
Creating a suitable growing environment is necessary to ensure good plant growth in a plant factory, which requires wireless sensor networks (WSNs) to monitor the environment in real time. However, existing WSN clustered routing methods hardly take into account the network unreliability caused by varying link quality among nodes, resulting in reduced stability and accuracy of environmental monitoring. This study proposes a wireless sensor network system strategy for improving network reliability in large-scale reliable wireless sensor networks suitable for plant factory scenarios. Firstly, a hybrid wireless sensor network was designed and built based on Wi-Fi and ZigBee communication protocols. Secondly, a nonlinear link quality prediction model for plant factory scenarios was developed using a function fitting method, taking into account the interference and attenuation caused by the dense concentration of agricultural facilities and plants in plant factories on the wireless signal propagation. Finally, a network coverage optimization scheme was designed by combining a particle swarm optimization (PSO) algorithm and link quality prediction model, and a reliable cluster routing protocol was designed by combining K-means algorithm. The results indicated that the coefficient of determination (R\({}^{2}\)) for the prediction model was 0.9962. The impact of agricultural facilities and vegetation on link quality was most significant when the node height was 0.7 m. Under the optimal node deployment, the number of nodes was 33, and the network coverage rate (CR) reached 97.512%. Compared with the traditional clustered routing method, the wireless sensor network designed in this study is more applicable to the field of plant factories; it further enhances data transmission effectiveness and link quality, improves the reliability of the network, and realizes the load balancing of the internal transmission of the network, which in turn ensures the accuracy of environmental monitoring and the stability of the system.  
wireless sensor network design; link quality assessment; network coverage optimization; cluster-based routing algorithm +
Footnote †: journal:  
Article
# An Improved RAIM Availability Assessment Method Based on the Characteristic Slope
###### Abstract
ARAIM is still in the theoretical research stage and is not currently being applied in engineering practice. Compared with ARAIM, RAIM has two deficiencies. The first is that RAIM is designed for a single constellation, monitoring only a single satellite fault [2]. ARAIM is designed for double constellations, monitoring not only the single satellite fault but also the multiple satellite faults and the constellation fault [12]. The second is classic, and the enhanced PLs are not rigorous enough for RAIM availability assessment, while the PL of ARAIM is much more rigorous. However, the on-board calculation of RAIM using the classic or the enhanced PLs is much less than that of ARAIM. For a single constellation, RAIM can still be used, but there is a problem needs to be considered, founding a RAIM availability assessment method both satisfying the rigor and maintaining the low on-board computational burden. In this paper, a slope-based RAIM availability assessment method is proposed to solve the above problem. The characteristic slope is taken as the assessment basis. Using the ideal slope threshold, this method can achieve a consistent RAIM availability assessment with the ideal-PL-based method. The ideal slope threshold can be calculated offline and searched online because it is only related to one geometric parameter. The remainder of this paper is organized as follows: Section 2 states some technical backgrounds. Section 3 reviews PL-based RAIM availability assessment methods, including the classic, enhanced and ideal PLs. The deficiencies of the classic and enhanced-PL-based methods can be analyzed quantitatively using the rates of optimistic or conservative assessment. Section 4 proposes the slope-based RAIM availability assessment method after the derivation of the ideal slope threshold. Section 5 gives an overview of the simulation results of the classic-PL-based, enhanced-PL-based, ideal-PL-based and slope-based methods. Section 6 concludes this work with a brief summary. The discussion of this paper takesvertical integrity as an example, using one kind of classic RAIM snapshot algorithm, i.e., the least squares residuals (LSR) algorithm. In this paper, the measurement noise is assumed to be independent white Gaussian noise (WGN).
## 3 Results
### NDVI--Commercial Variety  
The Treemap graph in Figure 2 shows the mean value of the Normalized Difference Vegetation Index (NDVI) for all treatments at all three salinity levels of the commercial variety. In general, it appeared that under normal irrigation, NDVI continued to increase with plant growth, only in the biopriming treatment (T3). At the salinity level of 80 mM NaCl, the index continued to increase in the hydropriming (T2), biopriming (T3) and hydropriming/biopriming (T4) treatments, while at 160 mM NaCl salinity, the increase in the index continued across all treatments: no-priming (T1), hydropriming (T2), biopriming (T3), and hydropriming/biopriming (T4).  
In Figure 3, the four priming treatments were compared with each other within each DAS separately for each salinity level to assess their effect on the NDVI. The results showed that at the time point of 25 DAS, the no-priming treatment (T1) showed the highest values of NDVI index with statistically significant differences from the other treatments at 0 and 80 mM NaCl salt levels. At the time point of 52 DAS, hydropriming (T2), biopriming (T3), and hydropriming/biopriming (T4) treatments gave slightly higher values of the NDVI index compared to no-priming (T1) treatment at all salinity levels without statistically significant differences.  
Figure 1: Treemap plot of the mean values of the eight priming treatments (four for each treatment). The average values for each treatment for each characteristic are displayed as rectangular squares. The rectangular squares are arranged in rows in descending order. The largest average values are placed on the left side of the row, and the smallest average value is placed on the right. Different Latin letters indicate significant differences according to the test of Least Significant Difference (LSD) at \(p<0.05\). T1: no-priming, T2: hydropriming, T3: biopriming, T4: hydropriming/biopriming, FWR: Fresh Weight Root, DWR: Dry Weight Root, FWS: Fresh Weight Shoot, DWS: Dry Weight Shoot, RL: Root Length, SL: Shoot length, BIO: Biomass, R/S: Dry Weight Root/Dry Weight Shoot.
# Hyperspectral Imaging to Evaluate the Effect of Irrigation Water Salinity in Lettuce
## 4 Conclusions  
Hyperspectral images were applied in a non-destructive manner to evaluate the effect of salinity on lettuce leaves at harvest. These images were studied in order to determine the best combination of wavelengths for diagnosing the problem of salinity in lettuce leaves.  
Based on the spectral features, two models were proposed. The first model was based on a principal component analysis of the second derivative mean spectra of the leaves and normalized with SNV. PC1 was most related to the changes in the leaves induced by salt concentration. By projecting the conveniently processed hyperspectral images on the PC1, the corresponding virtual images of scores showed clear differences among the leaves for each saline treatment.  
The second model was based on an LSI index focused on the red edge region. Several indexes from literature exhibited ability to sense the salinity effect on the leaves. However, LSI was the most discriminant index compared to them. This fact could indicate that the detailed interpretation of the spectra behavior could enhance the performance of indexes in each particular cultivar and condition. Once the index is proposed, a less expensive multispectral system could be employed to compute the respective virtual images (only three wavelengths were actually required).  
An analysis of variance using only about 1% of pixels extracted at random from the total population of pixels of each leaf showed significant differences between the leaves for each salinity level; in an industrial application, this allows for the implementation of a hyperspectral or multispectral device with smaller spatial resolution. This could simplify the technology, managed data volume and hardware requirements of the system, making it more economical and faster.  
Hyperspectral images allow for observations of the distribution of the salinity effects on the surface of the leaves, which are more intense in the areas furthest from the veins. Marginal necrosis appearing in leaves of plants under salinity stress can be detected by the artificial images before the damage is visible.  
Further research will be necessary to validate these models with larger data sets and salinity ranges and different varieties and growing conditions than those examined in this study.  
The funding of this work was supported by the MICINN through projects Multihort (AGL2008-05666-C02-01) and QualityLeaf (AGL2013-48529-R). LPF-TAGRALIA is part of the CEI Moncloa Campus.  
[PERSON], [PERSON] and [PERSON] conceived and designed the experiments, and wrote the article. [PERSON], [PERSON], [PERSON], [PERSON] and [PERSON] performed the experiments. [PERSON] analyzed the data. [PERSON] and [PERSON] contributed reagents and materials, provided knowledge about plant physiology and reviewed the article. [PERSON] contributed chemometrics tools, provided knowledge in chemometrics and data analysis, and reviewed the article. [PERSON] provided scientific knowledge and reviewed the article.  
The authors declare no conflict of interest.
## 5 Hall Thruster Erosion Reduction Concepts
Ionization and ion acceleration occur outside the thruster exit plane [113; 114]. The external discharge plasma thruster removes the SPT walls altogether and places magnets in the thruster baseplate [115]. The resulting electric and magnetic field configuration is similar to that generated by a circular planar magnetron [34]. Thruster erosion may also be reduced by substituting the BN or BN-SiO\({}_{2}\) in the SPT walls with a material of lower sputtering yield. Efforts have attempted to use diamond [116], BN-SiO\({}_{2}\) reinforced with SiA1 ON [117], and BN reinforced with Al\({}_{2}\)O\({}_{3}\)-SiO\({}_{2}\)[118]. There is also interest in replacing the Hall thruster wall material with nanomaterials that could be engineered to have low sputter yield, self-healing properties, or even the capability to influence the thruster discharge in a way that shields the walls from ion impact [119]. The use of novel materials in thruster walls requires more development and testing.
## 4 Case Study and Results
### Comparative Analysis
#### 4.3.4 Operational Applications  
The proposed modeling framework has several real-world applications:  
Figure 8: Linear correlation between payload mass and energy consumption (Line 2, all scenarios).  
Figure 7: Comparison of energy consumption across all scenarios for a 5 kg payload.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Line** & **S2 vs. S1** & **S3 vs. S2** & **S4 vs. S3** \\ \hline Line 1 & +12.9\% & \(-\)1.8\% & +10.7\% \\ Line 2 & +10.2\% & \(-\)2.5\% & +9.6\% \\ Line 3 & +8.9\% & \(-\)1.1\% & +12.2\% \\ Line 4 & +8.7\% & \(-\)2.2\% & +10.1\% \\ Line 5 & +11.2\% & +0.7\% & +12.0\% \\ \hline \hline \end{tabular}
\end{table}
Table 9: Relative Energy Increase Between Scenarios (5 kg payload).  
* **Battery dimensioning:** Identifying the minimum required energy reserve for each delivery profile and route.
* **Mission planning:** Adjusting UAV speed and delivery timing based on bus schedules and service constraints.
* **Energy prediction:** Estimating real-time energy demand onboard to avoid infeasible missions.
* **Lifecycle planning:** Estimating battery usage and replacement needs based on urban delivery patterns.  
By capturing realistic variations in power demand, this framework can be embedded in pre-flight planning tools or onboard autonomy stacks.
# A Novel Bitrate Adaptation Method for Heterogeneous Wireless Body Area Networks
## 4 Heterogeneous WBAN Simulator
### The Results of Measurements Used in the Simulator
#### 4.2.4 The Probability of the Correct Detection of the Direct Visibility Conditions  
According to (1), the difference in the estimated TP value and the estimated FPP value allows the determination of the conditions of direct visibility of the MN and the RN antennas. Determination of the LOS/NLOS condition is used as a factor for conditioning the assignment of other obtained parameters, e.g., the radio channel attenuation. In the real propagation environment, it is not possible to detect the LOS/NLOS conditions with 100% probability due to the fluctuations of the signal amplitudes, channel frequency selectivity, and the multipath phenomena. It was decided to compare this probability, which determines the quality of the AMASD method, based on the raw _xLOS_ parameter, i.e., \(P(xLOS)\), and based on the filtered _xLOS_/ parameter, i.e., \(P(xLOS\prime)\), as described in Section 3. In Table 3, the results of the probabilities for all the measurement scenarios estimated based on the known geometry of the corridor and the RDMs are presented.  
In all cases, the probability of detecting the LOS/NLOS conditions, \(P(xLOS)\), based on the raw data is greater than 0.83. However, considering the importance of this data and the principle of operations of the AMASD method, this is a value below the 0.95 acceptability threshold set by the authors. Therefore, it was decided to apply a low-pass filtration (3) to minimize fluctuations in the TP and the FPP difference, which is affected by the rapid change of the propagation conditions. The filtration allows the acceptable probability values of \(P(xLOS^{\prime})~{}=~{}0.97\) to be obtained and, therefore, it was used in the proposed AMASD method presented in Figure 2.
## 4 Autonomous Landing Method
### SLA Determination
#### 4.2.1 Prior Structure Data  
With respect to satisfying the computational accuracy, the catenary equation of the power line satisfies the following assumptions: (1) the loads acting on the power lines are uniformly distributed and point in the same direction; and (2) the power line is a flexible material that can only withstand tensile forces but not bending moments. According to these two assumptions, the power line is suspended from towers with a spacing \(l\), taking the shape of the catenary due to a uniformly distributed load \(\gamma\). The shape of a power line with suspension points of unequal height is shown in Figure 7. Points \(A\) and \(B\) are suspension points, point \(O\) is the lowest point, and \(f_{x}\) is the sag.  
At the lowest point, the slope of the catenary is zero, i.e., the inclination angle of the power line \(\alpha=0\). The differential equation [47] for the catenary is solved, obtaining the catenary equation of power line as follows:  
\[y=\frac{\sigma_{0}}{\gamma}\bigg{[}c_{h}\frac{\gamma(x-s)}{\sigma_{0}}-ch\frac {\gamma s}{\sigma_{0}}\bigg{]}=\frac{2\sigma_{0}}{\gamma}sh\frac{\gamma x}{2 \sigma_{0}}sh\frac{\gamma(x-2s)}{2\sigma_{0}} \tag{8}\]  
where \(s\) is the horizontal distance from the lowest point \(O\) to the origin point \(A\), and \(\sigma_{0}\) is the axial stress at the lowest point. The boundary conditions of point \(B\) (\(x=l,y=h\)) are substituted into Equation (8) to obtain:  
\[s=\frac{l}{2}-\frac{\sigma_{0}}{\gamma}arcsh\frac{h}{\frac{2\sigma_{0}}{ \gamma}sh\frac{\gamma l}{2\sigma_{0}}} \tag{9}\]  
The power line is affected by the FPLIR's gravity, which makes its shape difficult to obtain using an accurate mathematical model. To solve this problem, COMSOL soft  
Figure 6: Schematic of the FPLIR landing at power line. (**a**) Changes in power line slope and landing area. (**b**) the FPLIR walks on the power line.  
Figure 7: The power line with unequal height suspension points.  
ware is used to simulate the power line model affected by the additional concentrated force to obtain the shape of the power line. It is assumed that the FPLIR lands without slipping, and the maximum starting slope of the walking motor is \(\theta\). Because the mass of the FPLIR is much smaller than that of the power line, the power line slope does not drastically change. The FPLIR is suspended at eight points with slopes of \(\theta-3,\theta-2\), \(\theta-1,\theta,-\theta,-(\theta-1),-(\theta-2)\)and \(-(\theta-3)\), respectively, to study the slope variation. Since the numerical simulation is too slow to meet the requirement of real-time FPLIR landing, the following steps are used to determine the safe area in practical applications:  
1. Before FPLIR inspection, the OPTL information is stored in the database of the onboard computer.
2. The OPTL information is associated with safe slope data in the database.
3. When the FPLIR inspection starts, the slope of the power line is calculated using the algorithm provided in Section 4.2.2.
## Application of Auxetic Foam in Sports Helmets  
[PERSON] 1,*(r), [PERSON] 2, [PERSON] 3(r), [PERSON] 1, [PERSON] 4 and [PERSON] 4  
1 Centre for Sports Engineering Research, Sheffield Hallam University, Sheffield S1 1 WB, UK; [PERSON]DDRESS]  
2 Adidas Futures Team, Portland, OR 97217, USA; [EMAIL_ADDRESS]  
3 School of Engineering, Manchester Metropolitan University, Manchester M1 5 GD, UK; [EMAIL_ADDRESS]  
4 Materials and Engineering Research Institute, Sheffield Hallam University, Sheffield S1 1 WB, UK; [PERSON] (O.D.); [EMAIL_ADDRESS] (A.A.)  
* Correspondence: [EMAIL_ADDRESS]; Tel.: +44-0114-225-3996  
Received: 18 February 2018; Accepted: 19 February 2018; Published: 1 March 2018  
Featured Application: Auxetic open cell foam was used as the comfort layer within a sports helmet and has been shown to reduce the severity of linear impacts. The work undertaken highlights the potential to further develop auxetic open cell foam as comfort layer and create more effective sporting protective equipment to reduce transmitted linear as well as rotational accelerations during an impact.  
This investigation explored the viability of using open cell polyurethane auxetic foams to augment the conformable layer in a sports helmet and improve its linear impact acceleration attenuation. Foam types were compared by examining the impact severity on an instrumented anthropomorphic headform within a helmet consisting of three layers: a rigid shell, a stiff closed cell foam, and an open cell foam as a conformable layer. Auxetic and conventional foams were interchanged to act as the helmet's conformable component. Attenuation of linear acceleration was examined by dropping the combined helmet and headform on the front and the side. The helmet with auxetic foam reduced peak linear accelerations (\(p<0.05\)) relative to its conventional counterpart at the highest impact energy in both orientations. Gadd Severity Index reduced by 11% for frontal impacts (38.9 J) and 44% for side impacts (24.3 J). The conformable layer within a helmet can influence the overall impact attenuating properties. The helmet fitted with auxetic foam can attenuate impact severity more than when fitted with conventional foam, and warrants further investigation for its potential to reduce the risk of traumatic brain injuries in sport specific impacts.  
auxetic foam; helmet; concussion; sport; protection; impact attenuation
## 3 Results and Discussion
### Optimization of Experimental Conditions
#### 3.3.4 Optimization of Enrichment Time  
The influence of the enrichment time on the sensitivity of the uranyl sensor was investigated over a time period of 5-25 min while the condition of maintaining the other experimental conditions constant. It can be seen from Figure 5D that the corresponding voltametric signal strength increases with the increase of accumulation time up to 20 min and then remained almost constant. While, upon the further increase of the enrichment time of uranyl ions the intensity of the voltammogram signal remained basically unchanged and the enrichment time reached the adsorption equilibrium, which can be attributed to the adsorption saturation on the electrode surface. In order to shorten the analysis time as much as possible, improve the work efficiency and the sensitivity of the sensor, the time of 20 min was selected for further studies.
# A Cross-Layer Media Access Control Protocol for WBANs
## 1 Introduction
This leads to inefficient allocation of network resources, as they cannot be adjusted based on the importance of data packets, making it difficult to achieve coordinated optimization of service quality and energy efficiency. To address the issues above, we present a power adjustment and cooperative relay-combined cross-layer MAC (PACR-MAC) protocol for WBANs. The differentiated transmission requirements of heterogeneous data are considered. It provides flexible power adjustment and data retransmission mechanisms, ensuring both improved energy efficiency and network service quality for important data transmission. Additionally, through a lightweight point-to-point cooperative transmission scheme, we determine whether low-energy nodes require assistance from other nodes and select the optimal collaborating node for relay transmission, further enhancing the network's overall lifetime. The main contributions of this paper are summarized as follows:  
1. We optimize the MAC protocol to accommodate the differentiated reliability requirements of heterogeneous data transmission. Both TDMA and CSMA mechanisms are simultaneously adopted to meet the transmission requirements of both periodic data and event-triggered data. Meanwhile, taking into account the importance of data, the protocol incorporates a mechanism for data retransmission to ensure reliable transmission of critical data. 2. We propose a priority-based power adjustment scheme to improve the network QoS and energy efficiency. The proposed method allows nodes to calculate the base transmission power based on the channel state and further adjust the data transmission power according to the real-time importance of the data. This provides differentiated transmission power for heterogeneous data. 3. We present a cooperative relay scheme to further prolong the network lifetime. A concise point-to-point cooperation determination mechanism is used to decide whether there is a need for intermediate nodes to relay data and to determine the optimal cooperative node for the task. The remainder of this paper is organized as follows: Section 2 presents the related works. Section 3 introduces the network model. Section 4 explains the proposed work. Performance evaluations and results are discussed in Section 5. Finally, Section 6 concludes the paper.