esa-sceva/satcom-chunk-collection huggingface dataset:
# Security in Wireless Sensor Networks: A Cryptography Performance Analysis at MAC Layer
## 2 Related Work
### MAC Energy Issues on WSNs  
A network's energy efficiency may be improved at each protocol stack layer, and the MAC layer represents a critical point in WSN energy issues [14]. In the literature, various MAC protocols have been developed, and many of them deal with energy aspects [6].  
Many methods are proposed with the main task of improving the energy efficiency of these systems at MAC layer. An approach based on MAC for enhancing energy efficiency is provided in [15]. The solution provided by authors incorporates energy harvesting devices (EHDs) and analytic information, such as the estimation of the network lifetime. Moreover they provide a review of the MAC protocols that deal with this topic.  
For a WSN, power drainage is a priority issue associated with the MAC layer. So, in [16] the authors propose an improvement of the sensor medium access control (SMAC) operating on its fixed duty cycles. Their idea is to break duty cycles into micro ones with a variable time mechanism. They prove the best performance of the proposal.  
In [17] the authors compare two MAC contention-based protocols in terms of energy: SMAC and TMAC. Nodes using these protocols can be in sleeping or listening state. Nodes are able to save energy while they are in the sleep state by turning off the radio module. Their analysis is proved by simulative results.  
Duty cycling is chosen as the major mechanism for conserving energy in WSNs. Many studies deal with this mechanism in order to analyse the efficiency of MAC protocols. In [18] the effect of duty cycling in MAC protocols and their effect on energy consumption is analysed by the authors throughout the use of a tunable MAC protocol able to perform tuning of the duty cycle to see the energy levels.  
In [19], a proposal is made to reduce the problem of idle listening or collisions, as well as the energy consumption of the existing S-MAC protocol. With a study of the trade-off between energy consumption and delay, the influence of duty cycle change in line with data traffic has been given throughout the use of NS2 software simulator.
# Verification of Industrial Worker Walking Efficiency with Wearable Hip Exoskeleton
## 4 Discussion
### Treadmill Walking
The degree of muscle fatigue can be estimated from changes in the frequency range (spectrum) of electromyography [32]. Therefore, while increased muscle activity implies increased strength, increased muscle fatigue implies a shift from high to low frequencies. Sometimes, to maintain a certain level of muscle strength, muscle contractions that cause muscle fatigue may occur, leading to a further increase in the recruitment of motor units [33]. The GCM's reduction in muscle fatigue when walking on level ground is expected to increase work efficiency by reducing fatigue in the calf muscle while wearing a WIM for long periods of time in industrial fields with extensive movement. In a similar previous study, [PERSON] et al. (2017) reported a decrease in RF muscle activity when wearing a walking-assistive exoskeleton and found that the walking-assistive exoskeleton under study (GEMS) not only directly reduced the walking strategy of the hip joint but also reduced muscle use by reducing knee and ankle maneuvering [13]. Although the driving mechanism of the exoskeleton used by [PERSON] et al. in 2017 was different from the one used in this study, the reduction in muscle effort from the use of the wearable exoskeleton was interpreted as a similar result for the walking efficiency of both products [13]. In addition, our results showed that energy expenditure, oxygen uptake, EEM, total EE, and net EEM decreased significantly during treadmill walking (all \(p<0.001\)). Oxygen uptake decreased by 7.9% and total EE decreased by 7.3%. These results are similar to [PERSON] et al. 's study in 2017. He reported that oxygen consumption decreased by 7% and total EE decreased by 6.6% when wearing the GEMS exoskeleton and that GEMS induced efficient walking in older adults by reducing cardiopulmonary metabolic costs [13]. A recent study, using a hip-assistive soft exoskeleton receiver, reported a 17.4% reduction in net metabolic energy expenditure during treadmill walking in young adults [34]. In addition, [PERSON] et al. [35] and [PERSON] et al. [36] reported that the metabolic power decreased by 4.6% and 9.7%, respectively, when walking using a hip-assistive robot. In our study, the net metabolic power decreased by 10.6%, which was lower than the 17.4% obtained by [PERSON] et al. [34] but higher than the results of [PERSON] et al. [36] and [PERSON] et al., which demonstrated that the WIM device could reduce calf muscle fatigue and provide significant benefits with respect to cardiopulmonary metabolic efficiency.
# Differential Characteristics Based Iterative Multiuser Detection for Wireless Sensor Networks
###### Abstract  
High throughput, low latency and reliable communication has always been a hot topic for wireless sensor networks (WSNs) in various applications. Multiuser detection is widely used to suppress the bad effect of multiple access interference in WSNs. In this paper, a novel multiuser detection method based on differential characteristics is proposed to suppress multiple access interference. The proposed iterative receive method consists of three stages. Firstly, a differential characteristics function is presented based on the optimal multiuser detection decision function; then on the basis of differential characteristics, a preliminary threshold detection is utilized to find the potential wrongly received bits; after that an error bit corrector is employed to correct the wrong bits. In order to further lower the bit error ratio (BER), the differential characteristics calculation, threshold detection and error bit correction process described above are iteratively executed. Simulation results show that after only a few iterations the proposed multiuser detection method can achieve satisfactory BER performance. Besides, BER and near far resistance performance are much better than traditional suboptimal multiuser detection methods. Furthermore, the proposed iterative multiuser detection method also has a large system capacity.  
iterative multiuser detection; differential characteristics; threshold detection; error bit correction +
Footnote †: journal: Sensors
## 3 Results
### Analysis of Local Ecosystem Service Trade-Offs and Synergies
#### 3.3.2 Ecosystem Service Trade-Offs and Synergies  
A comprehensive Pearson correlation analysis was conducted on the five ecosystem services within the five ecological restoration zones, and the outcomes are depicted in (Figure 8). The correlations range from 0 to 0.8, highlighting substantial differences among the services. Predominantly, food production exhibits various degrees of trade-offs when compared to the other four services, while those services generally tend towards synergistic interactions. More specifically, the correlation metrics between food production and the quartet of other services vary between 0.2 and 0.6. The most pronounced trade-off appears between food production and water yield, marked by a correlation of 0.51. Conversely, the most minimal trade-off shows between food production and habitat quality, recorded at 0.28. Among the synergistic interactions, habitat quality and carbon storage present the strongest link, with a correlation coefficient of 0.86, the peak value observed. This is followed by robust synergistic correlations of 0.73 and 0.70 between soil conservation and habitat quality and soil conservation and carbon sequestration, respectively. These patterns correspond well with the observed spatial distributions of cold and hot spots for soil conservation, habitat quality, and carbon sequestration. In contrast, the interrelation between water yield and habitat quality registers the lowest correlation, below 0.1, suggesting a minimal synergy. This analysis reveals significant spatial variability in the interactions between ecosystem services across different zones, with clear distinctions in trade-offs involving food production and profound synergies among the other services, thus providing essential insights for managing ecosystem interactions effectively.
# Performance Evaluation of a Novel Propulsion System for the Spherical Underwater Robot (SURIII)
## 3 Hydrodynamic Analysis
### Dynamic Model of SURIII  
Generally, the 6-DoF dynamic equation of underwater robot can be given as [21; 23; 24],  
\[M\dot{v}+C(v)v+D(v)v+G=\tau+\tau_{wind}+\tau_{wave} \tag{1}\]  
where \(M\in\mathbb{R}^{6\times 6}\) is the sum of system mass matrix and added mass matrix, \(\dot{v}\) is the vector of generalized accelerations, \(C(v)\in\mathbb{R}^{6}\) is the Coriolis and centripetal matrix. \(D(v)\in\mathbb{R}^{6}\) is the damping matrix, \(G\in\mathbb{R}^{6}\) is vector of restoring forces and moments, \(\tau\in\mathbb{R}^{6}\) is the vector of generalized forces which input by control system and include the propulsive force and moment, \(\tau_{wind}\) and \(\tau_{wave}\) are vectors of forces generated by wind and wave. But effects of wind and wave usually occur in complicated marine environment, for our robot, these two factors can be neglectful. Hence, the dynamic equation can be simplified to Equation (2),  
\[M\dot{v}+C(v)v+D(v)v+G=\tau \tag{2}\]  
SURIII is a spherical robot and its structure is symmetrical, thus, \(M\) can be further simplified as follows,  
\[M=\left[\begin{array}{cc}mI_{3\times 3}&0_{3\times 3}\\ 0_{3\times 3}&I_{zz}\end{array}\right] \tag{3}\]  
where \(m\) is the sum of rigid body mass and added mass, \(I_{zz}\) is the resultant of inertia tensor. Also, \(M\) can be described as follows,  
\[M=M_{RB}+M_{A} \tag{4}\]  
where \(M_{RB}\) is the mass of the robot, \(M_{A}\) is the added mass. Moreover, \(C(v)\) is the sum of rigid body and hydrodynamic Coriolis matrix, so it can be expressed as,  
\[C(v)=C_{RB}(v)+C_{A}(v) \tag{5}\]  
The Coriolis force is generated by the rotation of the robot. The rotation speed of the SURIII is minute, so \(C(v)\) can be ignored in the hydrodynamic analysis. \(D(v)\) is an important parameter for the hydrodynamic analysis of the underwater robot. It contains the linear damping term \(D_{1}\) and nonlinear damping term \(D_{q}(v)\) and \(D(v)\) is give as,  
\[D(v)=D_{1}+D_{q}(v) \tag{6}\]  
\(G\) is the restoring force which contains gravity and buoyancy. It has been mentioned before that the SURIII has four DoFs: surge, sway, heave and yaw. In this research, the SURIII is considered as the suspended status underwater, the gravity is equals to the buoyancy. So, the influence of gravity and buoyancy can be ignored. Finally, the Equation (1) can be simplified as follows,  
\[(M_{RB}+M_{A})\dot{v}+\big{(}D_{1}+D_{q}(v)\big{)}v=\tau \tag{7}\]
## 3 Results and Discussion
### System Suitability and Method Validation of the Developed HPLC Analytical Method
 \\ \hline
**1** & 5.00 & 4.88 & 0.46 & 97.64 & 4.87 & 0.53 & 97.38 \\
**1** & 10.00 & 9.72 & 0.44 & 97.23 & 9.68 & 0.48 & 96.83 \\  & 20.00 & 19.50 & 0.19 & 97.51 & 19.49 & 0.32 & 97.44 \\  & 5.00 & 4.97 & 0.47 & 99.42 & 4.96 & 0.48 & 99.24 \\
**2** & 10.00 & 9.85 & 0.73 & 98.52 & 9.79 & 1.24 & 97.90 \\  & 20.00 & 19.79 & 0.39 & 98.93 & 19.65 & 0.57 & 98.27 \\  & 7.50 & 7.52 & 0.14 & 100.29 & 7.58 & 1.19 & 101.05 \\
**3** & 15.00 & 14.97 & 0.25 & 99.81 & 15.07 & 0.99 & 100.43 \\  & 30.00 & 29.96 & 0.79 & 99.88 & 30.04 & 0.80 & 100.14 \\  & 5.00 & 5.03 & 0.20 & 100.65 & 5.05 & 0.81 & 101.03 \\
**4** & 10.00 & 9.96 & 0.25 & 99.64 & 9.99 & 0.58 & 99.93 \\  & 20.00 & 19.83 & 0.18 & 99.17 & 19.98 & 0.84 & 99.92 \\  & 7.50 & 7.26 & 0.70 & 96.78 & 7.19 & 0.87 & 95.17 \\
**5** & 15.00 & 14.46 & 0.73 & 96.38 & 14.30 & 0.95 & 95.32 \\  & 30.00 & 29.01 & 0.53 & 96.71 & 28.80 & 0.62 & 96.00 \\  & 7.50 & 7.48 & 0.18 & 99.78 & 7.55 & 1.20 & 100.04 \\
**6** & 15.00 & 14.86 & 0.20 & 99.08 & 14.96 & 0.83 & 99.75 \\
**3** & 30.00 & 29.63 & 0.19 & 98.78 & 29.88 & 0.90 & 99.61 \\  & 5.00 & 4.99 & 0.35 & 99.75 & 5.03 & 1.16 & 100.55 \\
**7** & 10.00 & 9.90 & 0.23 & 98.97 & 9.96 & 0.87 & 99.60 \\  & 20.00 & 19.75 & 0.10 & 98.76 & 19.89 & 0.77 & 99.45 \\  & 5.00 & 4.86 & 0.37 & 97.13 & 4.90 & 1.10 & 98.00 \\
**8** & 10.00 & 10.00 & 0.32 & 99.98 & 9.86 & 1.53 & 98.55 \\  & 20.00 & 19.71 & 0.40 & 98.56 & 19.89 & 0.93 & 99.43 \\  & 5.00 & 5.00 & 0.32 & 100.01 & 5.04 & 1.20 & 100.75 \\
**9** & 10.00 & 9.93 & 0.27 & 99.31 & 10.00 & 0.86 & 99.98 \\  & 20.00 & 19.80 & 0.22 & 99.01 & 19.95 & 0.84 & 99.77 \\  & 5.00 & 4.97 & 0.85 & 99.50 & 5.02 & 1.09 & 100.32 \\
**10** & 10.00 & 9.91 & 0.62 & 99.05 & 9.95 & 0.62 & 99.50 \\  & 20.00 & 19.83 & 0.63 & 99.13 & 19.95 & 1.02 & 99.73 \\  & 5.00 & 4.98 & 0.14 & 99.68 & 5.02 & 1.04 & 100.26 \\
**11** & 10.00 & 9.90 & 0.22 & 98.99 & 9.96 & 0.75 & 99.43 \\  & 20.00 & 19.74 & 0.22 & 98.69 & 19.95 & 0.84 & 99.38 \\  & 5.00 & 4.99 & 0.11 & 99.81 & 5.03 & 1.12 & 100.50 \\
**12** & 10.00 & 9.91 & 0.19 & 99.14 & 9.97 & 0.79 & 99.56 \\  & 20.00 & 19.76 & 0.17 & 98.80 & 19.92 & 0.86 & 99.43 \\  & 5.00 & 4.97 & 0.14 & 99.49 & 5.01 & 1.14 & 100.66 \\
**13** & 10.00 & 9.89 & 0.18 & 98.90 & 9.94 & 0.78 & 99.78 \\  & 20.00 & 19.73 & 0.20 & 98.64 & 19.88 & 0.84 & 99.57 \\  & 5.00 & 4.98 & 0.21 & 99.65 & 5.03 & 1.42 & 100.70 \\
**14** & 10.00 & 9.90 & 0.22 & 98.99 & 9.96 & 1.09 & 100.51 \\  & 20.00 & 19.74 & 0.15 & 98.68 & 19.89 & 0.55 & 100.93 \\  & 5.00 & 4.99 & 0.10 & 99.83 & 5.03 & 1.18 & 100.70 \\
**15** & 10.00 & 9.92 & 0.16 & 99.20 & 9.98 & 0.92 & 99.89 \\  & 20.00 & 19.76 & 0.20 & 98.78 & 19.91 & 1.00 & 99.63 \\  & 5.00 & 4.97 & 0.28 & 99.47 & 5.04 & 1.17 & 100.55 \\
**16** & 10.00 & 9.95 & 0.20 & 99.50 & 10.05 & 0.86 & 99.67 \\  & 20.00 & 20.13 & 0.33 & 100.66 & 20.19 & 0.92 & 99.54 \\  & 5.00 & 4.99 & 0.12 & 99.7
## 3 Results  
### Direct ERA5 Comparison  
The ERA5-Land reanalysis provides meteorological variables with a 1 h time step. The linear [PERSON]'s correlation coefficients between the ERA5 variables and in situ observed variables are shown in Supplementary Table S1. The highest correlation coefficient values vary from 0.61 for wind direction to 0.99 for air pressure. The ERA5 variables that were used for direct comparison with local observation results are the surface pressure, temperature at 2 m, relative air humidity, and soil temperature at level 1. Wind speed and wind direction were calculated from U and V components of the wind speed at 10 m. Incoming photosynthetically active radiation was estimated from the surface solar radiation downwards divided by the constant derived from observations. The net radiation at the surface was accounted for as the sum of the surface net solar radiation and surface net thermal radiation. The results of direct comparison of variables are shown in Figure 3.  
Some of the studied variables from ERA5-Land data have good agreement with in situ observations. Atmospheric pressure according to ERA5-Land data is lower than observed by 3.5 hPa, and CC is 0.99 both for training and validation datasets. The difference for air temperature is more pronounced. Long-term average air temperature according to observations is \(-0.5\)\({}^{\circ}\)C and according to ERA5-Land data the temperature is \(-3.7\)\({}^{\circ}\)C. The ERA5-Land data underestimated the temperature in summer as extremely high. Incoming radiation, net radiation, relative air humidity, and soil temperature are reproduced by ERA5-Land with an average quality. A ratio of observed and ERA5-Land data varies in the range from 0.75 to 1.17, and CC varies in the range from 0.83 to 0.98. The worst agreement was obtained for wind speed and wind direction. It is clear that local wind is formed by localography conditions and it is weakly reproduced by the global circulation model. CC was 0.77 for wind speed and \(-0.56\) for wind direction. The ERA5-Land data were denoted as model ERA and compared with observations in the following sections.  
Therefore, direct use of ERA5-Land data for the describing of local weather conditions is not applicable, except for air pressure data. All other studied meteorological variables were reproduced in ERA5-Land data with serious biases. [PERSON] and [PERSON] [35] suggest a simple correction of reanalysis data. The de-biased ERA5-Land reanalysis data are denoted as the dbERA model and analyzed as with all other models in the following sections.
# A Matheuristic for Joint Optimal Power and Scheduling Assignment in DVB-T2 Networks +
## 4 A Matheuristic for DVB Design
#### 4.1.3 Initial Population  
We generate the initial population through inclusion of power vectors in which one single station is activated in only one direction and, for every station, we define one power vector for every discrete power value excluding the zero value. In a more formal way, for every \(s\in S\) and \(d\in D\), the initial population \(POP\) includes the vectors provided below:  
\[(0,0,\dots,\quad p_{sd}=P_{1}\quad,\dots,0,0)\] \[(0,0,\dots,\quad p_{sd}=P_{2}\quad,\dots,0,0)\] \[\vdots\] \[(0,0,\dots,\quad p_{sd}=P_{|L|}\quad,\dots,0,0).\]  
Such vectors provide \(|S|\cdot|D|\cdot|\mathcal{P}|\) initial individuals.  
Moreover, besides such elementary individuals, we enrich the population through more complex individuals with better fitness, identified by a variable-fixing-based procedure defined as follows. Let DVB-PI+\({}^{\text{RLX}}\) be the linear relaxation of DVB-PI+ and \((x,z)^{\text{RLX}}\) its optimal solution. We exploit DVB-PI+\({}^{\text{RLX}}\) as starting point to fix the value of a subset of variables in DVB-PI+ and obtain a smaller version of the problem that is easier to solve. We denote by DVB-PI+\({}^{\text{FIX}}\) the problem where some variables are fixed and the strategy for fixing consists of setting to 1 the variables whose value in DVB-PI+\({}^{\text{RLX}}\) is sufficiently close to 1. In a more formal way, we adopt this fixing rule:  
\[IF\qquad z_{sdl}^{\text{RLX}}\geq 1-\epsilon\qquad THEN\qquad z_{sdl}=1\]  
where \(\epsilon>0\). The rationale at the basis of this approach is that, if the value of a variable coming from a (tight) continuous relaxation of the problem (i.e., a version of the problem where the integrality requirement on variables is dropped and the mathematical strength of the relaxation is improved by adding valid inequalities) is sufficiently close to an integer value, then we have a good indication that the value of such variable should be set to the close integral value in a solution of good quality.  
For the proposed fixing, we focus just on the binary power emission variables since, due to the presence of the GUB constraints, they are particularly critical and, once that we set \(z_{sdl}=1\) for some triple \((s,d,l)\), we know that we can set \(z_{sd\lambda}=0\) for all other triples \((s,d,\lambda)\) with \(\lambda\in L\backslash\{l\}\). By adopting this fixing strategy, we obtain DVB-PI+\({}^{FIX}\), where we do not need to decide the power setting of some stations in some direction anymore and thus we face a smaller and, in general, easier to solve problem. DVB-PI+\({}^{FIX}\) is solved through CPLEX, with an imposed time limit, and all the feasible solutions identified during the solution process are added to the initial population.
## 1 Introduction  
Chromatic aberration elimination is a critical part of the optical lens design. The correction of chromatic aberration of the long and short wavelengths at either end of the visible light range is called achromatic correction. However, after correction of the two wavelengths, residual chromatic aberrations at other wavelengths remain, which is called the secondary spectrum. Chromatic aberration correction of three wavelengths including the central wavelength produces a lens which is called apochromatic while four wavelength chromatic aberration corrections are needed for a super achromat [1]. [PERSON] [2, 3] proposed a method for correction of chromatic aberration by selecting the four wavelengths of the F-line (wavelength 0.4861 \(\upmu\)m), d-line (wavelength 0.5876 \(\upmu\)m), C-line (wavelength 0.6563 \(\upmu\)m), and the other wavelength between 0.3650 \(\upmu\)m to 1.014 \(\upmu\)m combining three different glasses. In 1970, [PERSON] [4] used a system of four lenses to eliminate the chromatic aberration of the four wavelengths of 0.3650 \(\upmu\)m, 0.486 \(\upmu\)m, 0.6563 \(\upmu\)m, and 1.014 \(\upmu\)m. In 1977, [PERSON] [5] proposed a way to correct secondary chromatic aberration using ordinary glass. [PERSON] [6] used a graph method to design a doublet lens. [PERSON] [7] developed a method for correction of the longitudinal chromatic aberration for a doublet lens, which could correct the chromatic aberration for at least three wavelengths, and with some combinations for four wavelengths. [PERSON] and [PERSON] [8, 9] designed an equal optical path system, which can correct spherical aberration, coma, and longitudinal chromatic aberration for a doublet lens. [PERSON] [10] proposed a system for an apochromatic telescope. [PERSON] [11] used the Mach-Zehnder interferometer principle for the measurement of chromatic aberration. [PERSON] [12] developed a wide-angle eye model and [PERSON] [13] calculated chromatic aberration correction on the retina. [PERSON] [14] presented a microscope design for multi-band chromatic aberration correction. [PERSON] et al. [15] proposed a new method for the optimization and correction of chromatic aberration with double prisms, and applied it to a stereo photographic system with achromatic double prism arrays [16] and a doublet lens [17]. In 2010, [PERSON] [18] proposed an illustrating method for a triplet prism combination for minimizing the chromatic aberration.  
In our previous publication [15], the triple prisms can be incorporated to correct the chromatic aberration for a thin triplet lens design by increasing the thickness of the thick lens and the spacing between the lenses while maintaining the focal length of the triplet lens. To correct for the increased chromatic aberration caused by the lens thickening, we used an optimization algorithm combined with an illustration method to ensure that the chromatic aberration of the thickened triplet lens system is close to that of a thin lens system. Finally, the triplet lens design is tested with satisfactory results.