esa-sceva/satcom-chunk-collection huggingface dataset:
# A Study on Design Requirement Development and Satisfaction for Future Virtual World Systems
## 4 Virtual World Architecture Inspection
### Client/Server
#### Limitations  
The centralized ownership creates a single point of failure, leading to two issues. The first issue is persistency. When the entity owning a virtual world dies, bankrupts, or withdraws its operations, the affected virtual worlds will collapse together with the loss of its user-generated contents (Among the 126 virtual world applications based on OpenSimulator (see the inactive virtual world list in [[http://opensimulator.org/wiki/Grid_List](http://opensimulator.org/wiki/Grid_List)]([http://opensimulator.org/wiki/Grid_List](http://opensimulator.org/wiki/Grid_List))), 28 of them are no longer in operation). The result is that user content will become nonpersistent. Temporary infrastructure failure may also cause user content loss. For example, the World of Warcraft game server crash on 21 Jan 2006 led to the inventory damage of thousands of players [88].  
The second issue is credibility, which involves information and legal protection. User data of a virtual world may include sensitive information, such as location information in context-aware games [117]. One of the key privacy compliance issues is to provide a transparent and controlled environment to data owners [118], which is, however, at the cost of platform owner, and subject to many external factors (e.g., global societal trends), firm-specific factors (e.g., industry best practice and corporate culture), and ethical frame (e.g., rule utilitarianism or moral relativism) selection [119]. There are also some trust-level issues related to transparency, including requirement propagation along the subcontract chain and malicious insiders [118]. Thus, the gap remains between the platform owner's claims and the user's trust in their sensitive information protection.  
Moreover, storing user-created content on a C/S platform separates content ownership and control in social worlds, creating a legal dilemma. Users may own their content but may not have control over the actual data, while a platform can unilaterally terminate their accounts and confiscate their virtual asset, as in the [PERSON] case [120] and the [PERSON] case [121]. The separation of content ownership and control may lead to ownership tensions and inhibits user innovation [96]. The authors of [57] have shown that platforms tend to have such separation either for competition purposes or for liability safe harbor, which discloses the second problem. Storing user content imposes legal pressure on platform owners for copyright infringement or offensive content [122]. Though content moderation can mitigate such risks [86], it largely increases the cost paid by platform owners and the risks still exist.
## 5 Conclusions
### Nomenclature  
\begin{tabular}{l l l l} DC & direct current & \(G\) & conductance \\ CSO & cabled seafloor observatory & R\({}_{1}\) & the resistance of 1 km submarine cable \\ PFE & power feeding equipment & L\({}_{1}\) & the inductance of 1 km submarine cable \\ MARS & Monetary Accelerated Research System & C\({}_{1}\) & the capacitance of 1 km submarine cable \\ OOI & Ocean Observatory Initiative & \(f\) & the characteristic frequency of the \\  & Victoria Experimental Network & & undersea DC power system \\ VENUS & Under the Sea & \(\omega\) & the angular velocity of the undersea DC \\  & North-East Pacific Time-series & & power system \\ NEPTUNE & Underwater Networked Experiment & \(l\) & the overall length of the submarine cable \\  & Dense Oceanfloor Network System for & & \\ DONET & Earthquakes and Tsunamis & \(Z_{C}\) & the wave impedance \\  & Seafloor observation network for & & \\ S-net & earthquakes and tsunamis along & \(\gamma\) & the propagation coefficient \\  & the Japan Trench & & \\ ESONET & European Seas Observatory Network & \(z\) & the impedance of per unit length \\ MACHO & Marine Cable Hosted Observatory & \(y\) & submarine cable \\ ECS & East China Sea & \(Z\) & the impedance of a submarine cable \\ SCS & South China Sea & \(Y\) & the admittance of a submarine cable \\ CNSSO & Chinese national scientific seafloor & & segment \\  & observatory & & \\ AC & alternating current & \(R_{0}\) & the resistance of a cable segment \\ BU & branching unit & \(L_{0}\) & the inductance of a cable segment \\ SIIM & scientific instrument interface module & \(C_{0}\) & the capacitance of a cable segment \\ SI & science instrument & \(P_{L}\) & the power consumption of the undersea \\  & & & station \\ DPS & distributed power system & \(U_{L}\) & the input voltage of the undersea station \\ POL & point of load & \(I_{L}\) & the input current of the undersea station \\ CPL & constant power load & \(n\) & the number of submarine cable segments \\ \(i\) & current & \(P(i,u)\) & the mixed potential function \\ \(u\) & voltage & \(-A(i)\) & the current potential function of some \\  & & & non-energy storage elements in the circuit \\ \(t\) & time & \(B(u)\) & the voltage potential function of \\ \(\mu_{1}\) & minimum value & \(D(i,u)\) & non-energy storage elements in the circuit \\ \(\mu_{2}\) & minimum value & \(P_{u}\) & partial derivative of P to u \\ \(M\) & matrix & \(P_{i}\) & partial derivative of P to i \\ \(\lambda(M)\) & the eigenvalue of the matrix M & \(A_{ii}(i)\) & the second derivative test of A(i) to i \\ \(-R_{L}\) & the dynamic negative impedance & \(B_{uu}(u)\) & the second derivative test of B(u) to u \\  & of the CPL & & \\ \(R\) & resistance & \(L_{n}\) & diagonal arrays of branch inductance \\ \(L\) & inductance & \(C_{n}\) & diagonal arrays of branch capacitance \\ C & capacitance & & \\ \end{tabular}
# Decomposition of Multicomponent Micro-Doppler Signals Based on HHT-AMD
## 4 Simulation Studies and Performance Evaluation
### Influence of the SNR  
Signal-to-noise ratio (SNR) is a significant environmental factor in the signal processing [30]. In some cases, the micro-Doppler feature might not be presented in a recognizable and correct form because of the severe noise or weak modulation problem. In order to simulate a practical situation and understand the effect of noise on the proposed method, Gaussian white noise is added to the simulated signals here. Simulations were repeated for SNR of 0-30 dB. Suppose the signals are \(s(t)=\exp(-j20\sin(10\pi t))+\exp(-j10\cos(15\pi t))+n(t)\) over time interval \(0\leq t<1\) s and sampled with \(\Delta\)T = 1/256 s, where \(n(t)\) is Gaussian white noise with variance \(\sigma_{n}^{2}\). The DSR is considered, as a function of SNR plotted in decibel, see Figure 9.  
Figure 8: The comparison of DSRs (decompose success rates) against close-frequency ratio between HHT and HHT-AMD.  
Figure 9 describes the comparison of DSRs between HHT-AMD and HHT under varying SNRs. As we can see, when the SNR increases, the DSR increases. The DSRs of HHT are comparatively at a low level, which means that IMFs of the signals become corrupted, resulting in a loss of information. The DSRs of HHT-AMD are relatively higher than those of HHT all the time. A threshold effect appears at 12 dB SNR for the HHT and 8 dB SNR for the HHT-AMD. The increasing speed of DSRs of HHT-AMD is slower than that of HHT, which verifies the stability and the superior performance of proposed algorithm against noise. The results prove the robustness of HHT-AMD in decomposing multicomponent micro-Doppler signals corrupted by noisy circumstance as in a real environment.
# Weighted-CAPIC Caching Algorithm for Priority Traffic in Named Data Network
## 8 Conclusions  
This research proposed the Weighted-CAPIC caching algorithm to improve the priority class performance. Weighted-CAPIC works by adjusting different weights for every content class besides considering the variation of the content in providing a cache portion in the NDN router. Weighted-CAPIC provides the highest cache hit ratio for the priority class and the network, outperforming the Dynamic-CAPIC, Static-CAPIC, and LCD+Sharing scheme. The performance evaluation shows that the greater the number of request levels (the more dynamic consumer demand), the greater the total cache hit ratio provided by Weighted-CAPIC. Weighted-CAPIC can accommodate dynamic consumer demands more than all comparison algorithms in this study, i.e., Dynamic-CAPIC, Static-CAPIC, and LCD+Sharing. It is also very good at accommodating the various consumer request rates, with the low or high gap between each traffic class, and provides better performance with the same complexity as Dynamic-CAPIC. Weighted-CAPIC is also suitable for systems with dynamic consumer demand patterns and has a high priority gap for each traffic class. In this condition, Weighted-CAPIC can provide higher performance on certain priority classes. Weighted-CAPIC also provides a higher network/system cache hit ratio than Dynamic-CAPIC and all comparison algorithms, which means that Weighted-CAPIC allocates the cache portion for every class efficiently. But as compensation, Weighted-CAPIC reduces the cache portion of other classes that are of a lower priority.
# Physical-Mechanical Properties of Cupola Slag Cement Paste
## 1 Introduction
Another of the options proposed to achieve the most environmentally friendly concrete has been to recover waste as fines [17; 19; 20], even generating recycled concrete cements [21; 22]. There are very few studies that consider the possibility of recovering cupola slag in concrete. [PERSON] et al. [23] analysed the use of cupola slag as aggregates, both fine and coarse, and observed a large reduction in the mechanical properties of concrete. On the other hand, there are several studies on the use of cupola slag as a replacement for cement that show contradictory results. [PERSON] and [PERSON] [24] also analysed and concluded that cupola slag can be used as coarse aggregate effectively in structural as well as in plain concrete. [PERSON] and [PERSON] [25] concluded that the cupola slag aggregate concrete shows a satisfactory development and consistency in strength as compared to NAC. [PERSON] et al. [26] concluded that the use of cupola slag aggregates was possible to manufacture high density concrete while the use of the cupola granulated slag as the replacement of granulated blast-furnace slag in the production of cement-free concrete has not proved to be suitable. [PERSON] et al. [27] analysed whether cupola slag was reactive, but found that it was a residue with very little pozzolanic activity and limited the percentage of Portland cement replacement (OPC) to 20%, which implied a reduction in concrete properties of 13.5%. [PERSON] et al. [28] tested the effect of 35% OPC substitution with cupola slag and obtained an increase in compressive strength of 8%. [PERSON] et al. [29] analysed different substitution ratios and different water/cement (_w/c_) ratios, concluding that the effect of cupola slag is not seen until advanced ages and that for substitutions up to 10% there is no loss of mechanical properties. This 10% limit was also supported by [PERSON] et al. [30]. There are also a number of studies in which cupola slag is used as an admixture, obtaining concretes with good mechanical and durability properties [3; 4; 31]. For the production of ductile cast iron parts, such as the manufacture of water pipes, an internal mortar coating is also required to guarantee drinkability. In fact, this internal coating prevents any possible oxides generated in the pipes from passing into the water supply systems. In this study, the possibility of valorising the slag generated in the manufacturing process of ductile iron pipes by incorporating it into the mortar used in the inner lining is considered, in a notable exercise of circular economy. The starting hypothesis is to replace the iron and steel cement currently used with another cement made from the combination of an OPC and this finely ground slag. The result must necessarily give rise to a sulphate-resistant cement, which is a requirement for use in the internal lining of pipes for water distribution networks.
## 4 Conclusions  
The work used an ultra-precision milling process to machine a microlens array mold with an aspheric structure, and then a PMMA aspheric lens array was produced by compression molding technology. The profile replications and surface qualities of the lenses under different process parameters were analyzed, and an optical imaging platform was established to evaluate the imaging performance of the aspheric lens array.  
1. The molding temperature affected the final contour of the lens. When the temperature was lower than the Tg point, the deformation resistance of PMMA was too large to achieve sufficient deformation. Meanwhile, uneven internal-stress distribution affected the optical performance. Experiments showed that, at the molding temperature of 130 \({}^{\circ}\)C, the aspheric lens array could obtain better profile replication and surface quality (compared with the microlens at 110 \({}^{\circ}\)C, the filling degree is increased by 40%) and the optimal optical imaging performance. However, when the temperature exceeded 150 \({}^{\circ}\)C, obvious bubbles were generated inside the lens, which adversely affected the lens formation and imaging properties.
2. As the holding temperature decreased, the elastic recovery of PMMA became weaker. When the holding temperature was close to the Tg point, elastic recovery occurred inside the material at room temperatures, which affected the surface quality and contour fidelity. At the holding temperature of 50 \({}^{\circ}\)C, the aspheric lens array could achieve perfect profile replication with the molding defects, eliminating the optical imaging performance.
3. The molding pressure had the least significant effect on the lens profile's fidelity. By optimizing the molding pressure value, the filling degree was increased by 31%. When the molding pressure was greater than a certain threshold, the lens profile replication remained unchanged. The three process parameters--molding temperature, holding temperature, and molding pressure--significantly affected the forming quality and optical imaging.  
Conceptualization, F.G. and Y.L.; Methodology, F.G., and K.L.; Software, Y.L.; Writing--Original Draft Preparation, Y.L. and K.L.; Funding Acquisition, F.G. All authors have read and agreed to the published version of the manuscript.  
The authors gratefully acknowledge the financial support of the Natural Science Foundation of Guangdong Province (2018A030313466) and the Shenzhen Science and Technology Innovation Commission (SGDX20190919094403772).  
Not applicable.  
Data Availability Statement: Data is contained within the article.  
The author would like to appreciate the colleagues and advisor for their help to improve the paper.  
The authors declare no conflict of interest.
# A Variable Step Size Normalized Least-Mean-Square Algorithm Based on Data Reuse
###### Abstract  
The principal issue in acoustic echo cancellation (AEC) is to estimate the impulse response between the loudspeaker and microphone of a hands-free communication device. This application can be addressed as a system identification problem, which can be solved by using an adaptive filter. The most common one for AEC is the normalized least-mean-square (NLMS) algorithm. It is known that the overall performance of this algorithm is controlled by the value of its normalized step size parameter. In order to obtain a proper compromise between the main performance criteria (e.g., convergence rate/tracking versus accuracy/robustness), this specific term of the NLMS algorithm can be further controlled and designed as a variable parameter. This represents the main motivation behind the development of variable step size algorithms. In this paper, we propose a variable step size NLMS (VSS-NLMS) algorithm that exploits the data reuse mechanism, which aims to improve the convergence rate/tracking of the algorithm by reusing the same set of data (i.e., the input and reference signals) several times. Nevertheless, we involved an equivalent version of the data reuse NLMS, which provides the convergence modes of the algorithm. Based on this approach, a sequence of normalized step sizes can be a priori scheduled, which is advantageous in terms of the computational complexity. The simulation results in the context of AEC supported the good performance features of the proposed VSS-NLMS algorithm.  
acoustic echo cancellation (AEC); adaptive filters; data reuse; normalized least-mean-square (NLMS) algorithm; variable step size (VSS) +
Footnote †: journal: _algorithms_  
**Citation:** [PERSON]; [PERSON]; [PERSON] [PERSON]; [PERSON], [PERSON]; [PERSON], [PERSON]  
[[https://doi.org/10.3390/a15040111](https://doi.org/10.3390/a15040111)]([https://doi.org/10.3390/a15040111](https://doi.org/10.3390/a15040111))  
Academic Editor: [PERSON]  
Received: 25 February 2022  
Accepted: 23 March 2022  
Published: 24 March 2022  
**Publisher:** MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.
# A Review Paper on \"Graphene Field Emission for Electron Microscopy\"
## 3 Graphene-Based Cold Field Emitters
### Graphene Ring-Cathode Field Emitters
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & **Vacuum** & \begin{tabular}{c} **Work** \\ **Function** \\ **(eV)** \\ \end{tabular} & \begin{tabular}{c} **Chemical** \\ **Inertness** \\ \end{tabular} & \begin{tabular}{c} **Brightness** \\ **(A/m\({}^{2}\)srV)** \\ \end{tabular} & \begin{tabular}{c} **Energy** \\ **Spread** \\ **(eV)** \\ \end{tabular} & \begin{tabular}{c} **Current** \\ **Stability** \\ \end{tabular} & **Ref.** \\ \hline \begin{tabular}{c} **W-Cath Field Emitters** \\ **(157 nm)** \\ \end{tabular} & \begin{tabular}{c} **W-Cath Field Emitters** \\ **(157 nm)** \\ \end{tabular} & 4.5 & No & \(\sim\)10\({}^{9}\) & 0.2–0.3 & \begin{tabular}{c} 7.2\% \\ (UHV) \\ \end{tabular} & [4;16] \\ \hline \begin{tabular}{c} **W-Sethnicity Emitters** \\ **(157 nm)** \\ \end{tabular} & \begin{tabular}{c} Less \\ stringent \\ UHV \\ \end{tabular} & 2.8 & No & \(\sim\)10\({}^{8}\) & 0.5–0.8 & 0.23–3.1\% & [5;16] \\ \hline \begin{tabular}{c} **W-Cathode-Field Emitters** \\ **(157 nm)** \\ \end{tabular} & HV & 1.1 & Yes & \
\begin{tabular}{c} For 175 nm \(\sim\)10\({}^{9}\) \\ For 800 nm \(\sim\)10\({}^{8}\) \\ \end{tabular} & 0.2–0.4 &
\begin{tabular}{c} 5–10\% \\ (HV) \\ \end{tabular} & [77] \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Comparison of typical operating parameters and electron optical properties for the graphene coated point cathode and the state-of-the-art electron sources.
# Survey of Smart Parking Systems
###### Abstract
\begin{table}
\begin{tabular}{c c} \hline \hline
**Acronyms** & **Meaning** \\ \hline ACM & Association for computing machinery \\ AGS & Agent-based guiding systems \\ ANN & Artificial neural networks \\ APS & Research of algorithms for parking systems \\ BLE & Bluetooth low energy \\ CAPS & Centralized assisted parking search \\ CCTV & Closed circuit television (TV) \\ CITS & Crowdsourcing in intelligent transportation systems \\ CNN & Convolutional neural networks \\ CS & Crowdsensing \\ DFTP & Data from a third party \\ DS & Detection systems \\ EV & Electrical vehicles \\ EVPS & Electrical vehicle parking systems \\ GPS & Global positioning system \\ IEEE & Institute of electrical and electronics engineers \\ IRS & In-roadway sensors \\ ITS & Intelligent transport systems \\ MADM & Multiple attributes decision making guidance algorithm \\ ND & No data \\ NFC & Near field communication \\ NNP & Neural network prediction \\ OBU & On-board unit \\ ORS & Over-roadway sensors \\ PGIS & Parking guidance and information systems \\ PM & Prediction models \\ PRS & Parking reservation systems \\ RFID & Radio frequency identification \\ RQ & Research questions \\ RSU & Roadside units \\ SLR & Systematic literature review \\ SMS & Short message service \\ SPS & Smart parking systems \\ TRID & Transport research international documentation \\ V2R & Vehicle-to-roadside \\ V2V & Vehicle-to-vehicle \\ VANET & Vehicular ad-hoc network \\ VDT & Vehicle detection techniques \\ VLC & Visible light communication \\ VRP & Vehicle routing problem \\ WD & Without detection \\ WSN & Wireless sensor networks \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Acronyms and their meaning.
## 6 Conclusions and Future Work  
In this study, an ill-posed perceptual problem, two sources separation in monaural recordings, is addressed. Three different networks with different parameters are trained by a universal dataset and achieve excellent performances. More importantly, the most intuitive principle, proximity, is explored in simultaneous and sequential grouping experiments, respectively. Results show that the behavior characteristics of all networks are highly consistent with that of the human auditory system. If components are proximate in frequency or time, they are not easily separated by networks. Furthermore, the frequency resolution at low frequencies is better than at high frequencies.  
This study has a profound impact on deep learning and the auditory system. Instead of imitating specific structures such as the auditory periphery or cortex, the higher-level behavior characteristics of humans are simulated through optimization processes. Because networks are based on general principles similar to those in humans, it is possible to develop a universal system that can be adapted to all sources and various scenes or even adapted to multiple tasks simultaneously, such as the joint task of separation and recognition. It provides the possibility to achieve the remarkable ability of the human ear in many aspects such as separation, recognition, and location through deep learning and lays a scientific foundation for solving the holy grail of machine listening.  
Our study is the first step that explores the underlying mechanisms from the auditory system, while the network structures and parameters cannot be exhausted. More principles (such as common fate) and the interaction of principles also deserve further exploration. In addition, it is still an open question whether the characteristics of the training dataset determine the principles learned by networks. If certain components, such as those at high frequencies in datasets, are deliberately strengthened, the network may also be sensitive to the high-frequencies. It is similar to the schema-based principles in the human auditory system, which rely on knowledge or attention. It provides the possibility that a more flexible network in specific scenes can be obtained.  
Conceptualization, H.L. and L.W.; methodology, H.L.; software, H.L.; validation, J.L., B.W., and B.Z.; formal analysis, L.W.; investigation, H.L.; resources, J.L.; data curation, B.Z.; writing--original draft preparation, H.L.; writing--review and editing, K.C.; visualization, H.L.;supervision, K.C.; project administration, K.C.; funding acquisition, K.C. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the Open Fund of State Key Laboratory of Power Grid Environmental Protection, grant number GYW51201001554.  
The authors declare no conflict of interest.