esa-sceva/satcom-chunk-collection huggingface dataset:
# State of the Art in Metal Matrix Composites Research: A Bibliometric Analysis
## 2 Publication Distribution along Various Verticals
### Productive Organizations and Researchers Vertical  
This subsection discusses an analysis of the top ten institutes publishing MMC related articles in WoS during 2001-2020. Figure 8 shows that the Harbin Institute of Technology, China published the maximum number (335, 3.34%) of WoS papers in the field of metal matrix composites. The Shanghai Jiao Tong University, China published the second highest number (271, 2.71%) of WoS articles during 2001-2020. It was followed by the Chinese Academy of Sciences with a total of 227 (2.27%) publications in MMCs. The Indian Institutes of Technology arrived a close fourth with 225 (2.25%) publications during the same period. The National University, Singapore bagged 162 (1.62%) articles on MMCs, whereas the researchers at the National Institutes of Technology, India published 156 (1.56%) articles on MMCs. These were followed by the Northwestern Polytechnic University, China and the University of Science and Technology, Beijing, China with 132 (1.32%) and 118 (1.18%) publications, respectively. Finally, the Anna University, India and the Islamic Azad University, Iran arrived ninth and tenth on this list, wherein the affiliated researchers published 113 (1.13%) and 108 (1.08%) WoS papers on MMCs, respectively. This analysis showcases the detailed affiliations of the Chinese and Indian authors contributing significantly to the metal matrix composites research over the past two decades.  
Figure 7: The top 10 productive places.  
Figure 9 depicts the top 13 Indian institutions publishing MMC papers in WoS. Researchers affiliated with the group of Indian Institutes of Technology published the maximum articles (225) during 2001-2020. They were followed by the authors belonging to the group of the National Institutes of Technology, with 156 papers published in WoS. The Anna University arrived third with 113 papers, whereas the Council of Scientific Industrial Research (CSIR) came fourth with 75 articles in WoS. Other top publishing Indian institutions included the Indian Institute of Science, PSG College of Technology, Annamalai University, Vellore Institute of Technology, Siddaganga Institute of Technology, Amrita Vishwa Vidyapeetham, Thapar Institute of Engineering Technology and the Coimbatore Institute of Technology with 51, 47, 46, 39, 37, 32, 32 and 31 MMC papers in Web of Science, respectively.  
Table 1 lists the top ten researchers worldwide with maximum MMC publications in WoS. Although the topmost contributing author hails from Singapore ([PERSON], 140 articles, 1.40% of total corpus), all of the next nine top authors are affiliated with Chinese institutions.  
Figure 8: The top 10 productive organizations worldwide.  
Figure 9: The top 10 productive Indian organizations.  
This analysis highlights the presence of high output MMC research groups in China. The next section showcases an analysis of the various research collaborations in the field of MMCs.
## 3 DC Bus Voltage Control Strategy
### Improved Control Strategy Combined with the Variable Step-Size Algorithm  
In the LMS algorithm, the variation of the \(\mu\) value should ensure the algorithm has excellent convergence speed and steady-state error. The traditional fixed step-size algorithm fails to simultaneously ensure a positive correlation between the fixed step-size \(\mu\) and the convergence speed requirements and steady-state error. Therefore, \(\mu\) should be designed to vary with the iteration process to balance convergence speed and steady-state error.
## 2 Review of Phase-Locked Loops
### Computational Delay  
The previous section derived the coefficients of the closed-loop transfer functions in the discrete domain without considering the computational delay. The computational delay or transport lag is a time delay between the end of the integration process and the new NCO input (i.e., phase rate estimate), which is incurred by the calculation process at the discriminator and the loop filter. The computational delay \(t_{\rm D}\) exists in hardware and real-time software receivers without an appropriate buffering capability to eliminate this delay and should be considered in the stability analysis [14]. \begin{table}
\begin{tabular}{c c c c} \hline \multicolumn{1}{c}{\(s\)**-Domain:**} & & & \\ \multicolumn{1}{c}{**Continuous-Time Domain Expression**} & \(z\)**-Domain** & **Discrete-Time Domain Expression** & **Rule** & **Terminology** \\ \hline \(\frac{1}{s}\ \leftrightarrow\ y(t)=\int x(t)dt\) & \(\frac{1}{s}=\frac{T}{z-1}\) & \(y_{\rm SI}(k)=y(k-1)+T\cdot x(k-1)\) & Step-invariant & Forward rule, zero-order holder \\  & \(\frac{1}{s}=\frac{Tz}{2}\) & \(y_{\rm II}(k)=y(k-1)+T\cdot x(k)\) & Impulse-invariant & Backward rule, box car \\  & \(\frac{1}{s}=\frac{T^{2}+1}{2}\) & \(y_{\rm BL}(k)=y(k-1)+\frac{T}{2}[x(k)+x(k-1)]\) & Bilinear & Trapezoid, Tustin \\ \hline \end{tabular}
\end{table} 
Table 2: Digital equivalences to the analog integrator.
## 2 Materials and Methods
### Effects of Extraction and Desorption Times  
The experiment was conducted on air samples with standard additions of all analytes at 100 \(\upmu\)g m\({}^{-3}\). The following extraction times were studied: 1, 3, 5, 7, 10, 20 and 30 min followed by a 5 min desorption. Desorption times 1, 3, 5, 7 and 10 min were studied after 10 min extraction of analytes.
## 4 Description of the Proposed System
Whereas for the general case, the spheres are not in the same plane. Then, a coordinate transform system is needed to solve the problem, and finally we need another transformation to come back the original coordinate. The basic assumption assumed in this manuscript is used to simplify the coordinate transformation. For this simplified version, the (1 st), (2 nd), and (3 rd) spheres are centered at \((0,0,0)\), \((d,0,0)\), and \((i,j,0)\), respectively. Then, the mathematical formulation of the three spheres is expressed as follows:  
\[ \begin{array}{ll}r_{1}^{2}=x^{2}+y^{2}+z^{2}&\quad\quad(\text{first \,\,sphere})\\ r_{2}^{2}=(x-d)^{2}+y^{2}+z^{2}&\quad\quad(\text{second \,\,sphere})\\ r_{3}^{2}=(x-i)^{2}+(y-j)^{2}+z^{2}&\quad\quad(\text{third \,\,sphere}).\end{array}  \tag{16}\]  
The \(x\) value can be calculated based on \(r_{1}\), \(r_{2}\), and \(d\) by subtraction of the first and second equation as follows:  
\[r_{1}^{2}-r_{2}^{2}=x^{2}-(x-d)^{2}\to x=\frac{r_{1}^{2}-r_{2}^{2}+d^{2}}{2d}. \tag{17}\]  
If the obtained \(x\) value is substituted in the equation for the first sphere, then:  
\[y^{2}+z^{2}=r_{1}^{2}-\frac{\left(r_{1}^{2}-r_{2}^{2}+d^{2}\right)^{2}}{4d^{2 }}. \tag{18}\]  
It is clear from Equation (18) that the intersection between two spheres is a circle with radius as follows:  
\[r_{c}=\frac{1}{2d}\sqrt{\left(r_{1}^{2}-r_{2}^{2}+d^{2}\right)^{2}}. \tag{19}\]  
By considering \(z^{2}=r_{1}^{2}-x^{2}-y^{2}\), and substituting it in the expression of the third sphere, the \(y\) value is determined as:  
\[y=\frac{r_{1}^{2}-r_{3}^{2}-x^{2}-(x-i)^{2}+j^{2}}{2j}. \tag{20}\]  
Finally, the \(z\) value is calculated by substituting the \(x\) and \(y\) values in the equation for the first sphere as:  
\[z=\pm\sqrt{r_{1}^{2}-x^{2}-y^{2}}. \tag{21}\]  
The final result appears as the intersection between this circle (obtained by the intersection between (1 st) and (2 nd) sphere), and the (3 rd) sphere. If the (3 rd) sphere touches this circle in just one point, \(z=0\) is considered for this condition. If the intersection between the circle and sphere is two points, the root of the positive value in Equation (21) is selected. At the end, if this circle is bigger or smaller than the sphere that appears inside or outside of the sphere (without any intersection), this problem does not have any solution and it is considered as an error of the environmental noise. A (4 th) LED can be considered to prevent this condition, which triples the possible combination of spheres (\(\{1,2,3\}\), \(\{1,2,4\}\), \(\{2,3,4\}\), and \(\{1,3,4\}\)) to solve the problem. Further, when we have two intersections between the circle and sphere, one point can be eliminated (outside of the room dimension) by evaluating the size of the room.
# Towards Tamper-Proof Trust Evaluation of Internet of Things Nodes Leveraging IOTA Ledger
## 4 Proposed Methodology
### IOTA-Based Trust
#### 4.4.5 IOTA-Based Trust Score (ITS)  
To integrate these IOTA-based metrics into a unified trust score, we define the IOTA-based Trust Score (ITS) as follows:  
\[ITS=\alpha TCR+\beta CWC+\gamma RF+\deltaCTC \tag{13}\]  
where \(\alpha,\beta,\gamma,\delta\) are weighting factors that sum to \(1\). These weights determine the relative importance of each metric in the trust evaluation.  
We assign the following values based on the importance of each metric in trust evaluation:  
* \(\alpha=0.4\): Since transaction confirmation rate is a direct indicator of a node's reliability in handling transactions, it is given the highest weight.
* \(\beta=0.3\): Cumulative weight contribution reflects the node's role in transaction validation and propagation, making it the second most important factor.
* \(\gamma=0.2\): Reattachment frequency is assigned a moderate weight to discourage excessive reattachments, which may indicate unreliability or malicious behavior.
* \(\delta=0.1\): Cumulative transaction contribution is given the lowest weight, as transaction volume alone does not necessarily equate to trustworthiness.
# Chaotic Image Encryption: State-of-the-Art, Ecosystem, and Future Roadmap
## 2 Existing Surveys
### Surveys on Chaotic Image Encryption  
There are some reviews directly focusing on the applications of chaos theory in image encryption. However, some of the surveys studied above (including the one reported in [21]) are too outdated. Moreover, although a few of them develop a future roadmap, all of them fail to establish an ecosystem for chaotic image encryption.  
[PERSON] and [PERSON] [22] argued that a maliciously modified medical image makes it more difficult to diagnose an actual disease. This raises a critical need for the confidentiality of clinical images. On the other hand, the encryption time can pose a heavy overhead on the medical communication and processing systems. They claimed that this tradeoff is best resolved by DNA cryptography and chaotic cryptography. In their review, they reported some qualitative and quantitative measurements extracted from existing relevant research works to show how the tradeoff is resolved by the mentioned technologies. Moreover, they established some guidelines for further research in this area.  
[PERSON] and [PERSON] [23] believe that despite existing encryption and information hiding techniques, information can be stolen and copyrights can be infringed because of vulnerabilities in available methods. They first presented a review of state-of-the-art image encryption methods. They especially focused on joint encoding (error correction) encryption methods. Then, they proposed a novel method based on Low-Density Parity-Check (LDPC) code and chaotic maps with the support of the Advanced Encryption Standard (AES) and Substitution boxes (S-boxes).  
Some existing reviews take a comparative approach. For example, the advantages and disadvantages of existing chaotic image encryption methods were compared in [24]. Another relevant survey was reported in [25], where the authors reviewed and compared some one-dimensional chaotic maps with some hyper-dimensional ones with respect to their applications in image encryption. As another example, the authors of [26] highlighted chaotic encryption as a promising solution for encrypting images and videos, wherein neighboring pixels are highly correlated. They presented a review on existing chaotic methods for image encryption with the goal of identifying the most proper chaotic map.  
They studied tent map, logistic map, sine map, etc., and suggested [PERSON]'s cat map as the most promising chaotic map for this purpose. Moreover, in [27], the authors reviewed and compared image encryption methods based on five traditional algorithms, namely Blowfish, RSA, El-Gamal, AES, and DES with some chaos-based methods in terms of performance.
The approach is tested on residential loads with flexibility from air-conditioners and electric heaters, appliances with a high coincidence factor. Most baselining research focuses on the American power system. With the ongoing energy transition and increasing use of flexibility, the European perspective is however increasingly studied [7; 8; 16; 17]. In [17], baseline models are compared for the Baltic states. The statistical model as applied in France (see also [16]) is considered not to be viable, because of the immature flexibility market in the Baltic states. Regression-based models are dropped based on the USA market's rejection in 2009 [17]. The common practice in the EU is considered to be the window-before approach, in which meter readings taken before flexibility activation are used to set a baseline. An alternative is the window before and after approach, however this is considered to be more vulnerable to data manipulation [17]. The accuracy of this methodology is further limited when the flexibility source has a irregular consumption, a problem earlier identified by [4]. Until recently, baselining research focused on large-scale, predictable loads. As a result of the energy transition, it is urgent to increasingly utilise flexibility to avoid network congestion and overloading. This flexibility often consists of less predictable, small-scale loads such as EVs, HPs, battery energy storage and PV. Traditional baselining methodologies are not always suitable for these types of loads. Moreover, these baselining methodologies typically focus on a market-customer interface, whereas flexibility to avoid congestion and overloading of distribution grids needs to be settled between an aggregator party and a DSO. The contributions of this paper can be summarised as follows:  
* This paper analyses the baselining challenge on the interface between the DSO and an aggregator (i.e., day-ahead flexibility market), in the context of utilising flexibility in distribution networks. This topic is treated from a European perspective. * Three existing baselining methods are selected based on their simplicity and transparency and their applicability towards PV systems is evaluated, providing insight in their limitations. * A fourth (hybrid) method, maintaining simplicity and transparency, is proposed by the authors. This novel method overcomes some of the limitations of the first three methods, as shown in a proof of concept.
Therefore, to keep the control technique as simple as possible, and to make it readily applicable in an industrial context, we purposefully decided to perform a control synthesis on an experimentally identified linear approximation of the input-output behavior of the electrochemical subsystem of the SOFC. Future work will allow combining our experimentally identified transfer function models with the representations given in [7,8] so that the domains in which the controllers work accurately in a robust manner can be extended. The aforementioned experimentally identified system model is given in terms of a finite-order, linear time-invariant transfer function, which captures the following effects:* lag behavior of the gas supply valves;
* gas transport phenomena in gas supply tubes in combination with the delayed power variation if the amount of supplied fuel is changed; and
* the stationary gain between a constant gas supply and the resulting electric power for a representative current with approximately constant thermal operating conditions. It is, however, obvious that a linear time-invariant model cannot account for temporal (or state-dependent) coefficient changes. It has to be noted that the neglected phenomena act virtually on the linear plant model such as additive input disturbances. Hence, an integral output error feedback, IMC strategies as well as sliding-mode approaches that are capable of counteracting matched input disturbances are especially promising to implement a robust controller according to the aforementioned design aims. All controllers considered in this paper are, hence, developed on the basis of the experimentally identified input-output behavior of the electrochemical subsystem of the SOFC. This input-output behavior was determined by the Matlab transfer function estimator [9] using the experimental data gathered during previous work [10; 11; 12]. Details about this experiments-based modeling are presented in Section 2. For the controller design in Section 3, the a priori identified system was approximated by transfer functions of different order with delay representations that are given in terms of rational, minimum-phase transfer function elements. In addition, mass flow lag dynamics of the supply caused by the actuators inside the plant of the SOFC system were accounted for. Each controller was analyzed regarding its robustness against measurement noise and uncertainties in the plant dynamics including a gain mismatch of several tens of percent, as shown in Section 4. The two best controllers of this simulation case study, namely, the PI controller and the IMC, were implemented at a test rig available at the Chair of Mechatronics, University of Rostock to validate the results of the simulation in Section 5. Finally, Section 6 gives a conclusion and some insight on future work.
## 2 Passive Wake-Up Radio
### Discussion of the Passive Wake-Up Radio Parameters
#### 2.4.4 Data Rate and Modulation Scheme  
The values for the maximum data transmission rate were selected based on a bit error rate (BER) at the receiver. Shannon capacity draws a theoretical bound for the data rate as a function of the signal-to-noise SNR ratio at the receiver side [97]. The very high data rate at small transmit power produces many errors. Therefore, higher data rates require higher transmission power, which consequently results in higher energy consumption. Therefore, the data rate does not have a direct effect but can be a function of the transmission power, in relation to power consumption. For instance, the design in [84] has a low data rate and also very low power consumption. The design in [83], however, has a relatively high data rate of 200 kbps with a relatively low power consumption of ~2.3 uW.  
The frequency-shift keying (FSK) and amplitude-shift keying (ASK) modulation schemes are utilized in different wake-up radio designs. However, the on-off keying (OOK) modulation technique is preferred and more often used for the passive wake-up receiver. In the passive wake-up radio designs, the power consumption value of 2.3 uW measured in [83] is the highest recorded value in all the studies reviewed in our work utilizing the OOK scheme. The OOK is an envelope detection-based technique with low power dissipation feature. This makes it suitably embraced for the passive wake-up radios.
# Saturation Effect on the Coherency Loss of Spatially Varying Vertical Ground Motions
###### Abstract  
The effect of the influence regularity of site saturation and water level on the coherency loss between spatially varying earthquake ground motions (SVEGMs) in a vertical direction is not yet clear. Therefore, taking an onshore-offshore site as an example, the influence regularity of site saturation and water level on the coherency loss of SVEGMs in a vertical direction was studied, in which the saturation degree of the whole site (SD), the groundwater level (GWL), and the thickness of the surface water layer (WLT) were considered. Under each case mentioned above, a large number of vertical in-plane SVEGMs were synthesized and then correspondingly, the mean lagged coherency loss and phase angle of coherence function were obtained, and a series of comparisons were carried out to shed light on the varying trend of the value of lagged coherency loss and phase angle, with predefined parameters. The results showed that SD, GWL, and WLT possess significant effects on the varying trend of the coherence function of vertical SVEGMs.  
coherency loss; spatially varying earthquake ground motions; water saturation; water layer; influence regularity 2023
Recent Progress in Biochar-Based Photocatalysts for Wastewater Treatment: Synthesis, Mechanisms, and Applications  
[PERSON]  
1  
[PERSON] [PERSON]  
[PERSON] and [PERSON]  
1  
Footnote 1: [[https://github.com](https://github.com)]([https://github.com](https://github.com))  
and enhanced electronic conductivity [4]. [PERSON] et al. [18] first achieved the doping of carbon in the natural gas flame by heating the Ti metal. It significantly changed the absorption characteristics of the catalyst to visible light. Its photoelectric conversion efficiency can reach 8.35%, compared with that of pure TiO\({}_{2}\) (1.08%). [PERSON] et al. [19] found that the photocatalytic effect of carbon doping was five times higher than that of nitrogen-doped samples. [PERSON] et al. [20] compared the photocatalytic activities of carbon and nitrogen-doped TiO\({}_{2}\) samples under visible-light irradiation. They suggested the higher photocatalytic activity was due to the synergistic effect of carbon and nitrogen atoms. [PERSON] et al. [21] theoretical calculation results demonstrated the forbidden band gap of C-TiO\({}_{2}\) was narrowed down to 2.35 eV. They proposed that the introduction of carbon can narrow the band gap, thus enhancing the photocatalytic performance. However, the widespread application of carbon-based photocatalysts was most limited because of the high price and complicated fabrication methods of these materials. Thus, the development of cheap, sustainable and efficient photocatalysts will be of great interest (Figure 1).  
Biochar (BC) is produced through pyrolysis, gasification and hydrothermal carbonization of biomass. The biomass feedstocks include wood materials, forestry products, sludge, manure, agricultural residue and organic wastes. In comparison with most conventional activated carbon, biochar possesses a well-developed mesoporous structure and abundant surface functional groups. Furthermore, it can be served as a versatile catalyst or catalyst support [22]. In recent years, biochar-based photocatalysts (BCPs) have received great attention in various environmental fields [23; 24; 25; 26; 27]. Some of those recently reported BCPs were TiO\({}_{2}\)-coconut shell [28], TiO\({}_{2}\)-Salvinia molesta [29], TiO\({}_{2}\)-reed straw [30], TiO\({}_{2}\)-ramic char [31], TiO\({}_{2}\)-corn cob [32], TiO\({}_{2}\)-paper sludge and wheat husks [33], TiO\({}_{2}\)-bamboo [34; 35], ZnO-waste biomass [36], g-C\({}_{3}\)N\({}_{4}\)/FeVO\({}_{4}\)-pinus roxbu rghi [37], Bi\({}_{2}\)O\({}_{3}\)-corn cobs [38], TiO\({}_{2}\)-walnut shells [39], TiO\({}_{2}\)-olive pits and TiO\({}_{2}\)-wood shaving [40], TiO\({}_{2}\)-wood pellets [41], and TiO\({}_{2}\)-plum stones [42], etc.  
This review presents the recent development of typical BC-based photocatalysts used for wastewater treatment. Notably, a significant proportion of the review concerns the synthesis, mechanisms and applications of BCPs reported in literature, and provides useful suggestions for novel BCPs in photodegradation of wastewater.