esa-sceva/satcom-chunk-collection huggingface dataset:
# Extended Reality (XR) Engines for Developing Gamified Apps and Serious Games: A Scoping Review
## 4 Discussion
### RQ2. What Are the Main Features of XR Game Engines?  
The main features of XR game engines are listed as follows:  
* AR Marker with QR: The AR tag includes a QR code that encodes the unique resource ID of the object identified by the AR tag. Users can create their own AR marker models and objects regardless of the viewing device. It also allows AR markups to be recognized by viewers of an AR environment without embedding the design into the program. The AR tag can have the QR code on the back or incorporated into the text of the AR tag [109; 110].
* Projection-Based Augmented Reality: As the name suggests, this engine is a projection-based AR technique that produces an immersive light field on a flat surface to generate a 3D image. For instance, projection-based AR can be used to create holograms for educational purposes [111].
* Location-Based Augmented Reality: In this engine, the content is fixed to a specific physical space with location-based AR. It maps the real environment and determines the visual position of the user in the surrounding environment. When the device matches the map location, it overlays the digital image [112].
* Contour-Based AR: This engine outlines the silhouettes of objects and simulates real human interaction [113].  
As a part of the review, we conducted a comparative analysis of the game engines with respect to their XR features. The results are summarized in Table 4.  
Table 4 presents an analysis of the XR features supported in each game engine. The analysis involved verifying the suitability of each feature in each game engine by developing an example of these features to find out what they support. The majority of game engines used in the research support almost all features due to the increasing use of XR. The proprietary engines, Unity 3D and Unreal Engine 5, support all the XR features identified in this research. This can be explained by the fact that they both use native programming languages for app development and have an established presence in the market.
## 3 Development of the Generic Implementation Strategy
### Generic Implementation Strategy in the Broader Sense  
#### 3.3.1 Phase 3: Operation Phase  
In a broader sense, as already mentioned, the consideration of the life cycle phase of operation and decommissioning can also be relevant for the GIS. The operational phase of the DT essentially consists of operation and use as well as maintenance and evolution. After an operationally optimal and validated state has been established in the previous process step, this process step serves the operation of the DT, and thus, the provision of the defined functions and services that serve the use and generation of operational optimization [17; 49]. In detail, this means that before the operation starts, an operational procedure is defined on how the operational operation will be carried out. This can range from the planning of resources needed for operations to the definition of relevant performance operational criteria. In the preparation phase, constraints on operations are also captured, appropriate systems and services are provided, and essential training and operators for operations are identified and assigned. In the actual operation phase, the performance of the DT is recorded and monitored, which serves as the basis for any maintenance claims. Here, the DT, paired with its communication system of the IoT asset, unfolds its full potential and provides the services requested by it, such as the real-time monitoring of the IoT asset, for its stakeholders and other systems [54]. In other words, the DT enters into an exchange with its environment. Depending on the maturity level and use case, interoperable exchange with other DTIs, the DTA, can take place (see Section 2.3 and Figure 19).  
The maintenance and evolution process step serves to maintain and ensure the functionality of the communication system and the DT. Maintenance work is carried out here based on planned maintenance and servicing measures or due to reduced performance of the DT identified during operation. For this purpose, a maintenance concept is created which, among other things, defines planning, preventive measures and necessary resources that serve the maintenance of the DT and communication system. In addition to classic maintenance, the evolution of the DT is also of crucial relevance, as it also ensures the continued operation of the DT. For example, stakeholder exchange or changing environmental factors can result in an adjustment of requirements, which have direct or indirect effects on the communication system or the DT [17]. To ensure the continuity of the systems, a corresponding evolution may be necessary (see Figure 19).
# Survey of Smart Parking Systems
## 5 Algorithms or Methods Implemented in SPS
### Dynamic Algorithms  
In these types of algorithms, the fact that information can vary is prioritized, so that several searches are generally performed, allowing the information to be updated at certain intervals [3]. In general, they do not establish a re-planning of the trajectory toward a parking slot, but they do offer a better performance than the static algorithms [101, 141]. Those algorithms are able to react to ever-changing conditions in the context in which they operate.  
They are the mostly used in SPS because they are less complex to implement. This type of algorithm is most often found in PGIS systems, where, once a user enters areas with the smartphone's application active, the server determines the closest available parking place according to the user's preference and sends them the location [117]. Alternatively, the vacant parking slot detection circuit can detect if a parking space is available or not and transmits the data wirelessly to the parkingmanagement circuit. The system shows the closest available parking slot in accordance with the user's preference list in the database. It can also send the information via SMS [31].  
Multi-agent algorithms can be listed in this category. These algorithms are software programs (agents) that are continuously active. These algorithms can execute autonomous actions (either pro-active or reactive) and generally base their operation on user preferences. These agents that compose the algorithm can communicate with other agents to negotiate on a set of variables and make a decision for the problem in the background [255].  
In the context of SPS, finding a route to a car park through a single-agent environment is effective, but not efficient, in terms of optimization and competition for the car park. However, this considered search can be extended to multiple agents working and negotiating together to find the most beneficial routes for all users allows for route optimization, but its implementation complexity is high. This problem is an ongoing research topic [50].
# Artificial-Intelligence-Based Charger Deployment in Wireless Reshargeable Sensor Networks
## 5 Simulation Results
### Comparison of Energy Efficiency  
In this section, we compare the energy efficiency while the number of sensor nodes increased from 50 to 400. The x-axis represents the number of sensors, and the y-axis represents computational time. To ensure objectivity and accuracy, all of the algorithms performed 1000 iterations. The energy efficiency was determined by evaluating the power used by the sensor node. It is very wasteful if the sensor node receives too much power; however, it will not run out; conversely, the power will run out completely with insufficient power. This means energy efficiency needs to be good.  
Figure 5 shows the comparison of the energy efficiency with original algorithms and layoff versions. The energy efficiency of LSABC is better than that of SABC because LSABC can use fewer chargers to deploy in this environment. In other words, each sensor node can receive enough energy, as there are no useless chargers to add for overlapping areas.  
LTSBC uses the layoff algorithm to remove useless chargers and useless sub-solutions at the same time. The simulation showed that LTSBC has better energy efficiency than TSBC because overlapping areas will be decreased through LA.  
In the LGABC, the layoff algorithm ensures that all of the sensor nodes will be covered in each iteration, and it will remove useless chargers in the mutation. LGABC can find better solutions through the above-mentioned method. In other words, LGABC can decrease overlapping areas, and the energy efficiency will be increased at the same time.  
LACOBC can efficiently decrease the overlapping area. The reason is that LACOBC can check the status of coverage of all the sensors and ensure that LACOBC will not remove the important candidate chargers. For example, there is a sensor node which is only covered by one candidate charger; therefore, we cannot remove this charger because all of sensor nodes should be covered. Obviously, the simulation shows that the LA can enhance ACOBC to find the better solution and decrease overlapping areas.  
This simulation showed that the curve of energy efficiency will exhibit negative growth when the number of sensors decreases because the overlapping area will affect the quality of energy efficiency, and overlapping areas increase as the sensor nodes increase in number. The relationship of the number of chargers and energy efficiency is not a positive correlation. If there are many chargers and less overlapping area, it will still have high energy efficiency; this is the reason why energy efficiencies of LSABC and LTSBC will be close to those of SABC and TSBC.
## 4 Removal of Pharmaceuticals during Wastewater Treatment
### Biological Removal of the Pharmaceuticals  
Bacteria occupy a dominant place in the biosphere; through their various metabolic capabilities, they support the metabolic cycles that are fundamental to all life on Earth [59]. Researchers are investigating the potential of different bacteria to degrade pharmaceuticals and personal care products (PPCPs) into eco-friendly monomers, which could be an alternative emerging way to eliminate pharmaceutical residues from the ecosystem [60]. Mainly related to the bacterial populations concerned, technologies that use sludge (aerobic, activated, or granular) have been highly efficient in the treatment of municipal wastewater [61]. A study evaluating the efficiency removal of pharmaceutical products such as atorvastatin, caffeine, paracetamol, xylazine, trimethoprim, sulfamethoxazole, naproxen, fluoxetine, diclofenac, ibuprofen, clarithromycin, carbamazepine, atenol, azithromycin, erythromycinromycin, ketoprofen, metoprolol, erythromycinycin, ciprofloxacin, valsartan, simvastatin, and losartan, using activated sludge in the laboratory, at concentrations ranging from 13.2 ng/L to 51.8 ug/L in Latvia in municipal wastewater highlighted that biostimulation through the addition of nutrients to the sludge showed biodegradation of these pharmaceutical contaminants by Nitrospirae, Actinobacteria, Verrucomicrobia, Firmicutes, Acidobacteria, Proteobacteria, Chloroflexi, and Bacteroidetes. As well, some genera and species involved in removal processes of pharmaceutical compounds such as metoprolol, venlafaxine, fluoxetine, alprenolol, propranolol, bisoprolol, salbutamol, northuoxetine, gemfibrozil, and 17\(\beta\)-estradiol have demonstrated a 90% or higher removal efficiency [62]. Another study improved the efficiency of using a Gram-positive bacterium, designated as strain B1 (2015b) for the degradation of ibuprofen and naproxen, after six days for 20 mg/L of concentration and 35 days for 6 mg/L, respectively [63].  
The biodegradation of PPCPs could be a potential solution to eradicate this residue. This process is carried out by micro-organisms, which are more likely to decompose this pharmaceutical waste into biomass, methane, carbon dioxide, water, and various inorganic compounds, while the enzymes of organisms play a vital role. Pharmaceutical removal by biodegradation depends on what configuration is needed. The reactor configurations can be as simple as a sand column, WWTPs, and constructed wetlands, sequencing batch reactors, membrane bioreactors, which have been studied by many researchers [64]. Environmental parameters, including temperature, sunlight, atmospheric humidity, and ultraviolet rays, have also been shown to influence biodegradation [65; 66; 67].
## 4 Sorting Out Feasible Solutions
### Full Rotatability of Input Link  
The input link \(r_{1}\) of each mechanism is in the four-bar loop \(OABC\) shown in Figures 1 and 2. Hence, it is required for the four-bar to have a full rotatable crank as the input link. Among the four-bar linkages, those that allow complete rotation of the input link are the crank-rocker and double-crank, and each mechanism satisfies the following condition, respectively [38].  
\[\begin{array}{l}\text{Crank-rocker mechanism}:H_{1}>0,H_{2}>0,H_{3}>0,\\ \text{Double-crank mechanism}:H_{1}<0,H_{2}<0,H_{3}>0,\end{array} \tag{43}\]  
where  
\[\begin{array}{l}H_{1}=r_{0}-r_{1}+r_{2}-r_{3},\\ H_{2}=r_{0}-r_{1}-r_{2}+r_{3},\\ H_{3}=r_{2}+r_{3}-r_{0}-r_{1}.\end{array} \tag{44}\]  
The value of \(r_{0}\) in Equation (44) can be determined by the loop closure equation for the four-bar in each mechanism. From Figure 1 and Equation (2) for the Watt II slider-crank and Figure 2 and Equation (20) for the Stephenson III slider-crank, the \(x\)- and \(y\)-components of \(\mathbf{r}_{0}\) can be written as \(r_{0}\text{cos}\eta=r_{1x}+r_{2x}-r_{3x}\) and \(r_{0}\text{sin}\eta=r_{1y}+r_{2y}-r_{3y}\), respectively, where \(r_{1x}\) and \(r_{1y}\) are the prescribed values as free choices, and \(r_{2x}\), \(r_{2y}\), \(r_{3x}\), and \(r_{3y}\) are obtained from the solution of the synthesis equations. Then, \(r_{0}=(r_{0}{}^{2}\text{cos}^{2}\eta+r_{0}{}^{2}\text{sin}^{2}\eta)^{1/2}\). Similarly, since \(r_{ix}\) and \(r_{iy}\) (\(i=1,2,3\)) represent the \(x\)- and \(y\)-components of \(\mathbf{r}_{i}\) as defined in Equations (15) and (33), \(r_{i}\) in Equation (44) can be determined by \(r_{i}=(r_{ix}{}^{2}+r_{iy}{}^{2})^{1/2}\).  
Based on the condition provided in Equation (43), the solutions that allow the full rotation of the input link can be found from among all the solutions of the synthesis equations.  
The next section describes the displacement analysis for further discerning the mechanisms in which all the prescribed precision points are present on a single stroke of the output slider.
# On Modeling Antennas Using MoM-Based Algorithms: Wire-Grid versus Surface Triangulation
## 2 Materials and Methods  
This section presents a general mathematical formulation of the MoM solution of the integral equations. Then, the wire- and triangle-grid surface modeling approaches are overviewed. Based on them, two algorithms are developed and described together with their mathematical background and the codes (Wire-Grid and Triangle-Grid) built on their base. It is noteworthy that the general mathematical background of these approaches is covered and detailed in several literatures, for example in [10; 39]. In this paper, only the formulation required for the implementation of the algorithms are described.
###### Abstract  
Background: The application of virtual and augmented reality technologies to orthopaedic surgery training and practice aims to increase the safety and accuracy of procedures and reducing complications and costs. The purpose of this systematic review is to summarise the present literature on this topic while providing a detailed analysis of current flaws and benefits. Methods: A comprehensive search on the PubMed, Cochrane, CINAHL, and Embase database was conducted from inception to February 2021. The Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines were used to improve the reporting of the review. The Cochrane Risk of Bias Tool and the Methodological Index for Non-Randomized Studies (MINORS) was used to assess the quality and potential bias of the included randomized and non-randomized control trials, respectively. Results: Virtual reality has been proven revolutionary for both resident training and preoperative planning. Thanks to augmented reality, orthopaedic surgeons could carry out procedures faster and more accurately, improving overall safety. Artificial intelligence (AI) is a promising technology with limitless potential, but, nowadays, its use in orthopaedic surgery is limited to preoperative diagnosis. Conclusions: Extended reality technologies have the potential to reform orthopaedic training and practice, providing an opportunity for unidirectional growth towards a patient-centred approach.  
extended reality technologies; virtual reality; augmented reality; orthopaedic surgery; simulation; intraoperative; postoperative; artificial intelligence; mixed reality; extended reality +
Footnote †: journal: MedicalOrthopaedic surgery significantly benefits from these technologies, as they have been adopted for preoperative planning, intraoperative navigation and postoperative rehabilitation [8; 9]. Extended reality technologies have already been used to improve the performance of young surgeons and residents in arthroscopic knee surgery [10] and hip arthroplasty [11]. Furthermore, AR is commonly used to assist surgeons during specific procedures, such as minimally invasive surgery, spine surgery, and robot-assisted surgery.  
In some articles, authors also describe mixed reality (MR). MR may be defined as a hybrid between VR and AR. This technology is able to generate a virtual environment while also giving the user the possibility to interact with their surroundings. However, the functional and technical similarities in MR and AR applications make these two almost interchangeable [12].  
AI is adopted in orthopaedic surgery as well, with particular applications in imaging analysis and surgical training. The mechanism behind AI employs algorithms that recognize patterns in complex medical data received by the computer [13; 14; 15]. This technology could also aid surgeons by improving diagnostic accuracy and preventing human error [16].  
In conclusion, the following systematic review aims to assess the role of VR, AR and AI in orthopaedic surgery and their possible future value.
# Coordinated Mitigation Control for Wideband Harmonic of the Photovoltaic Grid-Connected Inverter
## 3 Resonance Suppression Method of LCL Filter
### Analysis of Frequency Domain Characteristics of Active Damping Method  
This paper set two group parameters of filter inductance and resistance to analyze the frequency domain characteristics of the active damping method, and these parameters are shown in Table 1.  
The Bode diagram of the equation between output current and voltage is obtained by substituting the parameters into Equations (2) and (4). Figure 10 shows the LCL filter's frequency characteristics from 10 Hz to 10 kHz.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Variable** & **Parameter 1** & **Parameter 2** \\ \hline \(L_{1}\) & 2.0 mH & 2.0 mH \\ \(L_{2}\) & 0.5 mH & 0.5 mH \\ \(C\) & 100 \(\mu\)F & 50 \(\mu\)F \\ \hline \hline \end{tabular}
\end{table}
Table 1: Parameters Table of LCL Filter.  
Figure 10: Bode diagram of LCL filter.  
From the above diagrams, if the inductance parameter is unchanged, the capacitance parameter determines the resonance point of the PV inverter. Larger capacitance corresponds to a lower resonance frequency point. Instead, smaller capacitance brings a higher resonance frequency point. Two group experiments with different parameters show that the active resistance can adaptively reduce amplitude gain at the resonant frequency, no matter how the resonance point changes. With the \(K_{\mathrm{c}}\) increasing, the amplitude gain at the resonant point decreases. When the \(K_{\mathrm{c}}\) is massive enough, the adverse effect is that the LCL amplitude gain has a small degree of decay, but the attenuation magnitude can be neglected. Meanwhile, it has little impact on other frequency response characteristics, so the LCL filter with active resistance can be seen as an ideal low-pass filter.
## 3 Results and Discussion
### Discussions
Based on the above analysis, pulse formation in a dispersion-compensated GaInN MLLD can be explained in terms of the saturation dynamics of the gain and SA section in the GaInN BS-LD. Thus, a soliton-like pulse formation mechanism may be involved due to the upward frequency shift of the SA. [PERSON] _et al._ reported pulse formation due to soliton-like mode locking in an external-cavity surface-emitting semiconductor laser [22]. They considered the positive intracavity dispersion and nonlinear changes in the refractive index of the gain medium and the SA. In the case of a GaInN MLLD, the pulse formation mechanism is similar, but absorption saturation can be the dominant cause of the frequency shift that balances the negative intracavity GVD. The large saturation effects in the SA and gain sections are associated with the high density of states in GaN-based semiconductors.
###### Abstract  
Antarctica is a region of the world where climate change is visible in the rapid melting of glaciers. This is particularly evident in marginal zones, where the pace of glacial retreat has systematically accelerated. The effective mapping of these changes is possible with the use of remote sensing methods. This study assesses changes in glacier margin positions between 1979 and 2018 in the Antarctic Specially Protected Area 128 (ASPA-128) on King George Island, South Shetland Islands, Antarctica. In 1979, 19.8 km\({}^{2}\) of the study area was glaciated. Over the following 39 years, an area of 6.1 km\({}^{2}\) became ice-free, impacting local ecosystems both on land and in Admiralty Bay. The reduction in glacier extent was different in time and depended on the glacier type. Land-terminating glaciers had the fastest retreat rates below 200 m a.s.l. and were influenced mostly by surface melting. The reduction of tidewater glaciers occurred primarily in areas below 100 m a.s.l., with the most pronounced ice extent decreases occurring below 50 m a.s.l. The observed rates of front retreat suggest that glacier retreat rates were fastest between 1989-2001 and 2007-2011, with reduced retreat rates between 2001 and 2007. During the last 7 years, the lowest rate of regression was recorded in the entire analysed period (1979-2018). Changes in the areal extent of glaciers were compared with the climate record available for King George Island. The observed fluctuations in glacier retreat rates could be correlated to oscillations in annual Positive Degree-Days. The spatial analyses were based on aerial photographs (1956, 1979), theodolite measurements (1989), GPS survey (2001, 2007), and satellite images (2011, 2018).  
**Keywords:** glacier recession; surface melting; climate change; temperature change; Positive Degree-Day