esa-sceva/satcom-chunk-collection huggingface dataset:
# A Review of Adsorbents for Heavy Metal Decontamination: Growing Approach to Wastewater Treatment
## 6 Factors Affecting the Adsorption Process
### Types of Adsorbent
#### 6.6.8 Ion Exchange Resins
Nanofiber-based ion exchange membrane was synthesised by the grafting of poly(acrylic acid) and poly(titaconic acid) to cellulose nanofiber mats [158]. Cadmium showed great attraction to poly (titaconic grafted acid) cellulose nanofiber mats in comparison to poly(acrylic acid)grafted cellulose nanofiber mats. PIA-based membranes were able to remove 220 mg Cd/g in comparison to traditional membranes. Highly porous styrene/2-ethyl hexyl acrylate/divinylbenzene was synthesised to produce polymerised high internal phase emulsion (ST/2 EHA/DVB polyHIPE) solid foams strengthened by the use of the different quantities of silica nanoparticles through emulsion templating [159]. The sulfonic group was introduced in the resultant ion exchange membrane by the use of sulphuric acid as a functional group. The adsorbent amount of 0.25 mg per 100 mL solution and pH value equal to 6 were considered to investigate the adsorption kinetics of nickel ions. It was found that an increase in the amount of silica up to 3 wt.% increases the efficiency of the ion exchange membrane from 3.6 to 3.9 meq/g and also the introduction of the sulphonic group increases the extraction of nickel ions. [PERSON] et al., synthesised sub-micro size polymeric ion-exchange resin (SMR) for the extraction of Pb\({}^{2+}\), Cu\({}^{2+}\), Zn\({}^{2+}\), and Ni\({}^{2+}\) from the aquatic systems along with natural organic matter. The river water and wastewater samples were tested with 153 varying concentrations of SMR particles (5, 50, and 500 mg/L). These ion-exchange resins were able to extract 82% of Pb, 46% of Cu, 55% \(\pm\) 20% of Zn, and 17% \(\pm\) 2% of Ni from stream water spiked with 500 \(\upmu\)g/L of every metal. Likewise, in devastating water, the polymeric ion-exchange resin was found to expel 86% \(\pm\) 0.1% of Pb, 38% \(\pm\) 0.8% of Cu, 28% \(\pm\) 1% 22 of Zn, and 11% \(\pm\) 1% of Ni. The resin was able to remove 10% or less organic matter from stream water and less than 4% from wastewater [160]. Figure 8: Adsorption isotherm for metal ions adsorption by cyshtcc-Fe\({}_{3}\)O\({}_{4}\), (**a**): Langmuir fit; (**b**): Freundlich fit; (**c**): Sips fit. Reused with permission from [155].
# Tradeoffs in Key Rotation Strategies for Industrial Internet of Things Devices and Firmware
## 2 Representative Architectures for Secure Boot
### Immutable Bootloader with Preslotted Multiple Public Keys (C)
When a public key \(P_{x}\) is referred (by way of a direct sequence number, a matching public key via firmware package, or a matching hash value), all prior keys (i.e., \(P_{1}\ldots P_{x-1}\)) are treated as invalid and are permanently revoked for that device. As such a revocation must be permanent, one way it is achieved is by introducing a one-time programmable (OTP) region with a monotonic counter [22] (e.g., Nordic nRF9160 and nRF5340). OTP monotonic counters work by allowing one-time half-word length write operation only where the original value of the half-word is 0 xff. At manufacturing, several half-word slots are preset to a value of 0 xff. The number of such slots is equal to the number of public keys provisioned. A slot  
Figure 2: Preslotted keys approach. corresponding to the index of the key is written with a non-0 xff value when such a public key is deemed retired. Thus, at any point in time, the number of such sequential OTP slots which have a non-0 xff value indicates the number of sequential keys retired. If a mechanism like an OTP memory region is not available, such a monotonic counter becomes a mutable element, and a motivated adversary can potentially alter its contents to effectively bring prior keys into effect. Considering the attributes in Table 1, this method represents a sweet spot of sorts. As outlined in Table 4, Boot Time is still relatively fast because the process can be implemented very efficiently. Dev Time is still short because the architecture is predefined and there is typically a lot of documentation that one could follow to have secure boot running quickly. It allows key rotation at every level (although limited to presolotted memory for key rotation at the lowest level). Memory protections, key access restrictions, revocation processes, etc., are built into the microprocessor design and, thus, by default, this aids the developer in setting up low-energy devices with secure methods for authenticating and loading firmware. The downside comes with the number of predefined slots, limiting the frequency of key rotation.
# On Mitigating the Effects of Multipath on GNSS Using Environmental Context Detection
## 2 Performance Evaluation of a Standard Multi-Constellation GNSS Receiver
### Experimental Sites/Route for Performance Evaluation  
The route used for dynamic performance evaluation is a 30 km long route that covers the center and surroundings of Sukkur city in Pakistan i.e, including residential and industrial areas as well as highways. The route contains a wide range of operating environments, such as clear open-sky at the N-65 highway, semi-urban and dense urban areas with small lane widths, high-rise buildings, flyovers and bridges and thus is a more realistic test-run for urban canyons. For detailed performance assessment, the experimental route is divided into four distinct observation windows labeled as P1, P2, P3 and P4 as shown in Figure 1.  
The observation windows are selected based on the type of environment and obstacles on the vehicle route. The first observation window, P1, in Figure 1 is 4 km long, which is an N-65 highway connecting Sukkur to other cities. The P1 is a two-lane one-way route with mostly clear open-sky views resulting in excellent radio signal reception. The second observation window, P2, is a 1.6 km long bridge on the river Indus known as Lloyd's Barrage. At P2, there are good chances of signal degradation (reflection or blockage) because of the structure of the bridge as shown in Figure 1.  
Then, a 4 km long route at the center of Sukkur city is taken as the third observation window (P3). P3 is a densely populated area with high-rise buildings, congested roads, flyovers and two cantilever bridges (Lansdowne Bridge) each 310 feet long, where there are significant chances of blockage and signal quality degradation due to high multipath/NLOS reception. Finally, a 5 km long route with little or no obstruction is taken as the last observation site and labeled as P4.  
This site has similar characteristics compared with those of P1. The route length, observation time and signal-reception characteristics of each of the observation windows are given in Table 1. Furthermore, the details of the field experimentation, which include the equipment used, number of constellation utilized, total time duration of each study and the antenna height, are given in Table 2.  
Figure 1: A 30 km long route covering the Sukkur city center and its surroundings used for field experimentation contain various operating environments, such as clear open-sky at the N-65 highway, semi-urban and dense urban areas with small lane widths, high-rise buildings, flyovers and bridges. The total route is divided into four distinct observation windows based on environment characteristics, and these are labeled as P1, P2, P3 and P4.
## 3 Results  
### Thermal Analysis  
TGA was performed on the adhesive samples to analyze their thermal decomposition to demonstrate differences in their chemical composition due to the presence of IPA in the studied samples. It can be observed in Figure 2a how the samples containing IPA started decomposing earlier than the baseline sample (0% IPA) at \(\sim\)100 \({}^{\circ}\)C, which is most likely due to the solvent causing a decrease in their crosslinking density and an increase in their chain mobility. Similar behavior was observed by [PERSON] et al. with 16 wt.% of acetone in an epoxy resin [6]. Figure 2b, which is an augmented version of what is located inside the dashed rectangle in Figure 2a, demonstrates how this behavior was more accentuated with increasing IPA content. All the samples experienced a sharp decrease in weight percentageswith a similar onset temperature (\(\sim\)320 \({}^{\circ}\)C). The adhesive samples containing 0, 2, 4, and 6 wt.% of IPA experienced a weight loss of around 2.3, 3.8, 4.8, and 6.2%, respectively.
# L-Band Erbium-Doped Fiber Optimization and Transmission Investigation +
###### Abstract  
The optical spectrum resource in the C-band has been used up due to dense wavelength division multiplexing (DWDM). Because of devices' compatibility with both the C-band and the L-band, the L-band is a good choice for further capacity expansion. Meanwhile, the mode division multiplexing (MDM) method has been applied to increase the number of channels. However, the few-mode erbium-doped fiber amplifier must be redesigned to overcome the power differences among channels. In this work, a few-mode erbium-doped fiber (FM-EDF) is optimized and manufactured. Then, an in-line gain-equalized L-band FM-EDFA is constructed. The experimental results show that the FM-EDFA works well in the wavelength range between 1575 nm and 1610 nm. The minimum differential modal gain (DMG) is 0.54 dB, and the maximum modal gain is 22.22 dB. Due to the excellent performance of the L-band FM-EDFA, a DSP-free transmission scheme in the L-band is demonstrated. The bit error rates (BERs) of each channel are below \(1\times 10^{-5}\) with a DSP-free receiver.  
L-band optical amplifier; few-mode EDF; gain equalization; real-time transmission test; bit error rate (BER) +
Footnote †: The optical spectrum resource in the C-band has been used up due to dense wavelength division multiplexing (DWDM). Because of devices' compatibility with both the C-band and the L-band, the L-band is a good choice for further capacity expansion. Meanwhile, the mode division multiplexing (MDM) method has been applied to increase the number of channels. However, the few-mode erbium-doped fiber amplifier must be redesigned to overcome the power differences among channels. In this work, a few-mode erbium-doped fiber (FM-EDF) is optimized and manufactured. Then, an in-line gain-equalized L-band FM-EDFA is constructed. The experimental results show that the FM-EDFA works well in the wavelength range between 1575 nm and 1610 nm. The minimum differential modal gain (DMG) is 0.54 dB, and the maximum modal gain is 22.22 dB. Due to the excellent performance of the L-band FM-EDFA, a DSP-free transmission scheme in the L-band is demonstrated. The bit error rates (BERs) of each channel are below \(1\times 10^{-5}\) with a DSP-free receiver.
## 4 Conclusions and Recommendations  
This study establishes an ophthalmoscope system that integrates the cloud and big data with a wearable-type ophthalmoscope, double working spectrum, and 3D image-taking technology in the same hardware design. This design allows patients to transfer the captured images to their ophthalmic hospital via the cloud method using big data, thus shortening the diagnosis time and increasing doctors' basis for diagnosis. Currently, the main research outcomes are as follows:  
Figure 8: Structural relationship between human eyes and 3D ophthalmoscope glasses.  
Figure 9: Schematic of the 3D optical mechanism.  
Image recognition experiment: The 3D image recognition rate (90%) was higher than the 2D image recognition rate (84%); this reached obvious significance and, thus, the 3D mechanism design was selected.
2. A glasses-type 3D ophthalmoscope lens mechanism design: A wearable ophthalmoscope with 3D image-taking features and visible-infrared working spectrum was developed. These features are suitable for the diagnostic tracking of eye fundus' imaging using a rotatable mechanism via a 3D optical structure design.
3. Ophthalmoscope lens design: Using imaging simulation technology, a set of ophthalmoscope lenses was designed to fit a glasses-type 3D ophthalmoscope; then, with the mechanism design, the specifications of wearable ophthalmoscope glasses were significantly reduced.
4. This proposed design and its mechanism can be connected with wireless networks, Bluetooth, or a cloud processing system in order to transfer the diagnostic images to the hospital and assist in the doctors' diagnosis via cloud technology and big data statistics.  
Optical zoom employed in wearable glasses will be in even higher demand in the future. The relay lens can be adapted to invert the images in the position of the glasses frame and will provide sufficient space to accommodate zoom optics, which may be three times larger than fixed focal optics.  
[PERSON] and [PERSON] conceived and designed the experiments; [PERSON] and [PERSON] performed the experiments. [PERSON] analyzed the data. [PERSON] contributed reagents/materials/analysis tools. [PERSON], [PERSON], [PERSON] and [PERSON] wrote the paper.  
The authors wish to thank the anonymous reviewers for their valuable suggestions. This study was supported by the Ministry of Science and Technology (MOST) of Taiwan under Contract No.: MOST 107-2221-E-005-050.  
The authors declare no conflict of interest.
## 3 Evaluation Methods of the Performance of GSP
### Common Laboratory Testing Methods
#### 3.1.6 Anti-Weather-Exposure Ability  
Anti-weather-exposure ability of GSP was tested by conserving samples in an exposing environment for 7 days, 90 days, 180 days, and 240 days. Its strength and fatigue life were shown no decline in Marshall stability test and cyclic wheel load test [114].  
In addition, thermal cracking equipment was adopted to evaluate long-necked specimens at \(-5\)\({}^{\circ}\)C. It was found the thermal resistance of GSP was positively related to the content and viscosity of binders [115].
# Predictive Control for Current Distortion Mitigation in Mining Power Grids
## 5 Conclusions and Final Remarks  
In this paper, a novel MPC strategy for power quality improvement was presented. The proposed scheme is deployable in mining industry environments once power systems of mining facilities are affected by low order harmonics (below 200 Hz), which are not easily filtered, even when AFE converters are used as the interface between rotary machines and the power grid. In this sense, the proposed controller optimizes the power required for harmonics compensation and prioritizes this objective over active power delivery to preserve the power quality inside the power system. Furthermore, the proposed optimization can be executed for real-time applications, once formulated in terms of harmonics magnitudes, allowing more extended sampling periods than the primary control level continuous-set implementations and integrating more restrictive constraints than reported in the reviewed literature.  
Although the results shown in this paper are promising, compensating harmonics pollution only in the PCC of mining facilities is not the most efficient scheme because harmonics currents are circulating through the power system. In this sense, some assumptions that our proposed scheme relies on should be covered by future research. The most important assumption is related to the a priori knowledge of harmonics components to be compensated, considering that, in mining facilities, harmonics profiles depend on machinery speed. In this sense, the deployment of computationally efficient methods of harmonics components provides additional features; therefore, the proposed control can be extended to consider this feature. Another open challenge relates to the development of distributed algorithms that allow cooperative compensation for multi-node power grids, which is the case for mining facilities. In this case, the challenge is to find an optimal information management system to reduce the performance requirements on the communication network (bandwidth, latency, and channel capacity), without sacrificing control performance.  
Conceptualization, J.S.G. and L.T.; methodology, L.T.; software, J.S.G.; validation, A.N.-F. and C.G.; formal analysis, J.S.G., L.T. and F.N.; investigation, A.N.-F; resources, F.F.-B; data curation, A.N.-F; writing--original draft preparation, J.S.G. and A.N.-F; writing--review and editing, L.T., A.Z.C. and F.F.-B.; visualization, A.N.-F; supervision, F.N., J.R. and A.Z.C.; project administration, FN.; funding acquisition, FN. All authors have read and agreed to the published version of the manuscript.  
This work was partially funded by ANID under grant ANID PIA ACT192013. F.-B. acknowledge the support of SERC Chile (CONICYT/FONDAP/15110019). C.G. and J.R. acknowledge the support of ANID/FONDECYT through projects FB0008, 1210208 and 1221293.
# Review of Recent Advances in the Application of the Wavelet Transform to Diagnose Cracked Rotors
## 2 The Wavelet Transform
### Discrete Wavelet Transform
#### 2.2.1 Multiresolution Analysis  
The concept of MRA was developed by [PERSON] and [PERSON] in 1986. MRA consists on the application of the DWT in a recursive way until the desired decomposition level is reached. Initially, the main disadvantage of MRA is that only approximation information could be decomposed in the different frequency bands, as shown in Figure 3.  
[PERSON] _et al._[49], applied MRA for a transverse crack detection using signals from an experimental set-up, using the RMS of the coefficients of the lower frequency bands.  
MRA has been used for crack detection with very good results for signals obtained from a Jeffcott rotor model combined with neural networks [50].  
MRA has been also applied to detect cracks growing in shafts using AE [23]. Specifically, envelope analysis combined with MRA has been applied with very good results. In [51], a comparison between vibration and AE signature was carried out. Using vibration signals, after MRA decomposition, diagnostic characteristics are observed. In the case of AE, envelope analysis was performed after wavelet decomposition, which allowed diagnostic information to become available.
## 2 Geology of the Ulleung Basin and Simulation Approach  
### Geology of the Ulleung Basin and Hydrate Class  
The Ulleung Basin is located in the Korean East Sea, between the Korean Peninsula and Japan. In order to develop gas hydrates as a potential energy source, geophysical surveys and geological studies of gas hydrates in the Ulleung Basin have been carried out since 1997. Moreover, two deep-drilling expeditions were completed in 2007 and 2010 [21]. Seismic profiles of the Ulleung Basin show that mass transport deposits and hemipelagic mud in the Ulleung Basin were generally interbedded with sandy turbidites [22]. Examinations of core and well-log data from the UBGH2 drill sites suggest that the UBGH2-6 location has relatively good gas-hydrate-reservoir-quality properties in terms of the individual and cumulative thicknesses of HBS with desirable textures (sandy) [23]. Water depth of UBGH2-6 is 2157 m, and seafloor temperature is 2.5 \({}^{\circ}\)C, with a geothermal gradient of 112 \({}^{\circ}\)C/km. The HBS is from 140 m below the seafloor (mbsf) to 153 mbsf.  
UBGH2-6 site appears to be a hybrid of two hydrate classes, i.e., Class 2 and Class 3 [11; 23; 24]. Class 2 comprises an HBS overlying a mobile water zone, and Class 3 involves a HBS confined between two near-zero permeability strata, such as shales. Because of the very low permeability of the muds in the overburden, underburden and interlayers, the characteristics of a Class 3 deposit are dominant [25].
## 5 Internal Control Techniques
### GSC Control  
The GSC is an important device with the function of controlling DC-link voltage and the reactive power exchange with the grid. With properly designed GSC controllers, DC-link overvoltage can be restricted during large grid voltage disturbances, as shown in Figure 21. \(U_{gd}\) and \(U_{gq}\) denote the \(d\)- and \(q\)-axis GSC output voltage.  
In Reference [80], a coordinated control method composed of a PI controller and resonant compensation was applied in DFIG-WTs to restrict torque and active power oscillations. Therefore, the dynamic performance of DFIG-WTs under unbalanced conditions could be improved. In Reference [81], a PI-DFR controller comprising a PI regulator and a dual-frequency resonant (DFR) was adopted in DFIG-WTs. By applying this coordinated control, the DC-link voltage oscillations could be restricted, and constant active power output could be ensured. Both the RSC and the GSC were controlled to provide a smooth and optimized operation.  
However, the linear control methods applied in GSC cannot predict the behavior of DFIG-WTs during severe disturbances. A discrete-time inverse optimal control method based on a neural network was proposed in Reference [82] to provide better dynamic performance for DFIG-WTs. Due to the on-line identification property of neural networks, the real-time neural inverse optimal (RNIO) controller design can be achieved without system parameters given, in which case the system robustness can be improved.  
Sliding mode control can also be applied in GSC internal control to alter the system dynamics. The proposed sliding mode control can control the GSC to ensure desirable DC-link voltage and steady active power output. In Reference [83], a nonlinear coordinated control method was applied to the GSC of DFIG-WTs to stabilize the internal dynamics. By using the proposed method, rotor overcurrent and DC-link overvoltage could be restrained and, thus, the LVRT capability could be enhanced.  
Figure 21: Grid-side converter (GSC) controller.
## 3 Problem Formulation
 \tag{3}\]  
The application must start and end at the same local processor, which is denoted as \(p_{s}\), so we have  
\[\sum_{r=1}^{L_{p_{s}}}x_{1p,r}=1 \tag{4}\]  
\[\sum_{r=1}^{L_{p_{s}}}x_{Np,r}=1 \tag{5}\]  
Each task can only be assigned to exactly one certain position on one processor, therefore,  
\[\sum_{j=1}^{M}\sum_{r=1}^{L_{j}}x_{ijr}=1,\;\forall i=1,\ldots,N \tag{6}\]  
where \(L_{j}\) represents the number of available positions on processor \(j\). Furthermore, each position on each processor can only be allocated to at most one task, which is given as:  
\[\sum_{i=1}^{N}x_{ijr}\leq 1,\;\forall r=1,\ldots,L_{j},\;j=1,\ldots,M \tag{7}\]  
Each task is required to be assigned sequentially to the available positions on each processor, which is imposed as follows:  
\[\sum_{i=1}^{N}x_{ijr}\leq\sum_{i=1}^{N}x_{ij(r-1)},\;\forall r=2,\ldots,L_{j},\;j=1,\ldots,M. \tag{8}\]  
For each task, the earliest time it finishes depends on the finish of all of its parent tasks. Moreover, it is also constrained by the time when the task occupying the last position on the same processor finishes. Hence, we have  
\[FT_{i}=\max(FT_{tx}^{(j)},FT_{pre(i)})+T_{ex}(i),\;\forall j\in G(i) \tag{9}\]  
where \(pre(i)\) represents the task scheduled at the last position of \(i\) and \(G(i)\) denotes the set of parent tasks of \(i\). We use \(FT_{tx}^{(j,i)}\) to denote the time when the results from \(j\) are received by \(i\), which is given as:  
\[FT_{tx}^{(i,j)}=FT_{i}+d_{pi;p}e_{ij} \tag{10}\]  
where \(p_{i}\) and \(p_{j}\) represent the processor where \(i\) and \(j\) are executed respectively. The finish time of each task executed on local processor \(j\) is constrained by:  
\[ \begin{split} FT_{i}-FT_{k}+C(2-x_{ijr}-x_{kj(r-1)})\geq T_{ex}(i)\\ \forall i,k=1,\ldots,N,j=1,2,\ldots,M,r=2,\ldots,L_{j}\end{split}  \tag{11}\]  
where \(C\) is set to be a relatively large positive number. It is guaranteed that the finish time of \(i\) on processor \(j\) is at least equal to the finish time of its preceding task plus the execution time of \(i\). Notice that the value of \(2-x_{ijr}-x_{kj(r-1)}\) is equal to 0 if and only if task \(k\) and task \(i\) are scheduled consecutively on processor \(j\). Moreover, our task-scheduling decision must meet the application deadline, which is imposed by:  
\[FT_{N}\leq T_{dl} \tag{12}\]  
Our goal is to reasonably schedule the tasks such that the finish time of the application is minimized, which is given by:  
\[ \begin{split}\text{min}\,FT_{N},\\ s.t.\text{ Equations (\ref{eq:11})--(\ref{eq:12})}\end{split}  \tag{13}\]