esa-sceva/satcom-chunk-collection huggingface dataset:
# A Novel Expectation-Maximization-Based Blind Receiver for Low-Complexity Uplink STLC-NOMA Systems
## 6 Conclusions  
We have proposed a novel low-complexity STLC-NOMA system for two-user uplink IoT networks. In summary, both STAs employ the \(M\)-ASK modulator and align their modulated symbols to each axis in the I-Q plane, respectively, before STLC encoding. Thanks to the characteristics of the STLC that remove the phase distortion caused by wireless channels, the signals of each STA are still aligned on their axis at the AP. Hence, the AP can detect the transmitted signals through the ML detector without joint detection. Simulation results have shown that the proposed novel uplink STLC-NOMA system is more efficient than the conventional uplink STLC-NOMA in terms of the computational complexity of the detector and BER performance under the low SNR regime. Furthermore, we have mathematically analyzed the exact BER performance of each STA in the proposed uplink STLC-NOMA system, and verified that the optimal spatial diversity order could be achieved. We also validated that these mathematical BER expressions are exactly the same as the Monte-Carlo simulation results. Finally, we have designed an EM-based blind energy estimation (BEE) scheme to blindly estimate the transmit power and effective channel gain of each STA at the AP and observed that it works well even for short packet transmission.  
Conceptualization, B.C.J.; methodology, K.-H.L.; software, K.-H.L.; validation, B.C.J.; formal analysis, K.-H.  
**Acknowledgments:** This work has been supported by the Future Combat System Network Technology Research Center program of Defense Acquisition Program Administration and Agency for Defense Development (UD190033 ED).  
**Conflicts of Interest:** The authors declare no conflict of interest.
## 4 Evaluation and Implementation  
In this section, the SNR performance simulation results are firstly presented. Afterward, the hardware implementation is compared with the existing works.
# Power Losses Investigation in Direct 3 \(\times\) 5 Matrix Converter Using MATLAB Simulink
## 3 Analytical Power Losses Calculation in Matrix Converter  
Due to the system symmetries, the global conduction power losses can be easily derived. In the 3 \(\times\) 5 matrix converter, every output phase has three switches connected to the input phases U, V, and W. Thus, output current determines power losses in all three  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Parameter** & **V\({}_{SAT}\) [V]@10A** & **V\({}_{F}\) [V]@10A** \\ \hline STGW15H120 DF2 & 2.6 & 3 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Parameters of the IGBT STGW15H120 DF2.  
Figure 2: Current flow in SiC-based bidirectional switch.  
bidirectional switches. For the IGBT-based matrix converter, the output phase current must be split to the positive and negative components, because due to the analysis in Figure 1, positive current flows through transistor Q1 and the internal diode of Q2, and negative current flows through transistor Q2 and the internal diode of Q1. Then, we can calculate average and rms current as follows [15]:  
\[I_{a(AV)}=\frac{I_{pk}}{3\pi} \tag{4}\]  
\[I_{a(RMS)}=\frac{I_{pk}^{2}}{12} \tag{5}\]  
where \(I_{PK}\) represents the peak value of the output current of the matrix converter. Losses in one bidirectional switch can be then calculated using:  
\[P_{IGBT}=U_{F}I_{a(AV)}+rI_{a(RMS)}^{2} \tag{6}\]  
Then, global power losses of one semiconductor can be calculated as follows [15]:  
\[U_{F}=30(U_{F,Transistor}+U_{F,\ Diode}) \tag{7}\]  
\[r=30(r_{Transistor}+r_{Diode}) \tag{8}\]  
With the use of formula, we can calculate the conducting power losses in the 3 \(\times\) 5 IGBT-based matrix converter.  
In the SiC (MOSFET)-based bidirectional switch, the situation is slightly different. Because the MOSFET transistor has channel with resistive character when conducting, bidirectional switch has only resistive power losses. Then, Equation (6) must be adjusted, and power losses in one MOSFET transistors can be calculated:  
\[P_{MOSFET}=\frac{\left(I_{pk}\sqrt{2}\right)^{2}}{12}r \tag{9}\]  
where \(I_{PK}\) is the peak value of the output current and r represents \(R_{DS(on)}\) of one MOSFET transistor in the bidirectional switch. For the global power losses in the 3 \(\times\) 5 matrix converter, \(r\) can be substituted as follows:  
\[r=30\Big{(}R_{DS(on)}\Big{)} \tag{10}\]  
The components parameters were used to calculate power losses using this analytical approach and results can be seen in comparison chapter of this paper.
## 1 Introduction
Measuring the electromagnetic field in order to reduce the electromagnetic influences (EMIs) requires avoiding the disturbance of the measuring probe in the measured EM field. Because this goal cannot be assumed for any probe, the solution proposed in [10] was to calibrate the measuring probe by placing it in a well-defined reference field. Moreover, since the EMF influence can be different depending on the position, a multi-point analysis achieved by moving/translating the probe was proposed [10]. Benefiting from the case of the analyzed planar emitter coil fed by a constant frequency and the spatially symmetrical micro-construction (2.5 mm radius) of the measuring head described in our paper, its influence on the measured field was practically negligible. Researchers know that the accuracy of field measurements depends on the probe/ transducer geometry, the transmission line features, and the signal processing circuit. How much the probe dimensions (loop and wire radius) affect the final results and how to determine the additional correction of the probe calibration factor were investigated in detail in [11; 12; 13]. Note that the concept described in [13] was based on the scalar compensation, while the concept developed herein is different and includes a vector calibration (module, direction, and sense). The system sensitivity (S) was defined in [14] as the derivative of the metric M (mean value or an RMS value) with respect to one relevant input parameter \(p\). The authors used optimization algorithms to improve the S value of the electronic oscillator circuit in order to increase the performance of a three-coil metal detector. The signal path of the metal detector included the classical components, such as a signal generator; EM-coupled coils; a digital amplifier; an oscillator; and a detector (filter, rectifier, oscillator), which generated the final marker signal (acoustic signal to the loudspeaker). Based on a similar pattern, in our work we proposed a signal path containing partially identical modules (signal generator, coupled coils, differential amplifier); however, in the proposed structure, we inserted rms-to-dc conversion and ADC modules, which delivered the final digital value. In this way, we ensured a unique and linear relationship between the input current in the WPT emitter coil and the digital sequence at the output. As another approach using the instantaneous Poynting vectors, the authors of [15] investigated the space- and time-dependent characteristics of the power and energy flux. The conceptual difference in our proposal was that our experimental structure was composed of a 2D emitter coil and a 3D sensor coil rather than two similar coils, Tx and Rx. The spatial measurements were conducted in all three orthogonal directions, H\({}_{\mathrm{x}}\), H\({}_{\mathrm{y}}\), and H\({}_{\mathrm{z}}\), not only in the plane. Our approach to calibration procedures for spatial radiation measurements differed from other methods [16; 17] because it included segmented signal path calibration from the 3D-OSC to the display.
## 1 Introduction  
Virtual Reality (VR), a relatively dormant technology for decades, has recently made rapid gains because of increasing demand from fields such as social networking, education, medicine, and gaming [1, 2]. The establishment of Oculus VR and the release in 2012 of the Oculus Rift headset accelerated the mainstream adoption of VR [3]. VR has become a global phenomenon influencing various aspects of society and business [3, 4]. The VR market is projected to reach USD 22.81 billion by 2024 and USD 131.93 billion by 2029 [4].  
Digital narratives greatly enhance the immersive quality of VR experiences [2]. However, although hardware advances, such as affordable headsets and high data-processing capability, are actively studied, few studies address digital narratives [1, 5, 6]. VR digital narratives allow users to shape their experiences, which greatly increases user engagement [7, 8, 9]. As technology advances, the study of digital narratives is becoming increasingly important.  
Digital narratives use two main approaches. The first is storytelling (ST), in which the narrative follows a predetermined structure. The second is \"storyliving\" (SL), in which users can manipulate the narrative [10, 11]. SL provides users of VR environments with a richer and more personalized experience [12, 13].  
Various studies utilize the SL approach. For example, a French spa town uses digitalization to provide an emotional experience that attracts younger customers [14]. A virtual tour of the Canadian Parliament allows visitors to explore at their preferred pace through a nonlinear interactive format [15]. Additionally, a nonlinear VR adaptation of [PERSON]'s plays provides deep immersion through multiple paths and choices [16].  
These studies demonstrate the effectiveness of SL in VR environments. However, they primarily focus on the theoretical aspects of SL and its direction rather than detailing methodologies and processes for its implementation. This study aims to address this gap through the proposal of a systematic methodology for implementing SL in spatially oriented destinations.  
Hanyangdoseong, Seoul's historic city wall, represents the history and culture of the Joseon Dynasty. Located in the city's heart, it has excellent accessibility and harmonizes with the natural landscape, making it an ideal subject for the development of nonlinear SL-based VR content [17, 18]. The wall preserves various landscapes, providing space for healing, leisure, and a glimpse into the past [19, 20]. These characteristics provide valuable visual and experiential elements for exploration in VR research.  
The objective of this study was to develop, using a nonlinear SL approach, an interactive VR system centered on Hanyangdoseong. The aim was to create a method through which users can experience narratives in a personalized manner while enhancing their understanding of cultural heritage.
# Review of Advancement in Variable Valve Actuation of Internal Combustion Engines
## 2 Variable Valve Timing (VVT) System
### Hydraulic VVT (HVVT)  
An HVVT system includes a hydraulically actuated cam phaser or variator, the design of which evolved over the last 40 years.  
The 1980 Alfa Romeo Spider 2.0 L had the first VVT system, which was an HVVT on the inlet camshaft. The design comes from a patented design (US Patent 4,231,330) by Alfa Romeo engineer [PERSON] [(43)]. The cam phaser is a cylinder containing a pressure chamber and a piston with helical splines. Alfa Romeo calls it mechanical VVT because of the helical splines, and it is classified as hydraulic VVT because of the hydraulic piston. Under oil pressure via a solenoid valve, the piston rotates slightly due to the helical splines and advances the inlet valve timing by 25\({}^{\circ}\) to increase engine valve overlap, which happens between 1500 and 2000 rpm and over 5000 rpm. Otherwise, the valve timing remains in its natural state.  
Most phasers of the later HVVT systems use a rotary vane hydraulic motor, which is actuated by pressurized oil controlled by a solenoid valve. The cam phaser is operated either in two settings or, as in most of the more recent systems, continuously.  
The BMW single VANOS system, when first introduced in 1992 on the BMW M50 engine, controlled the timing of the intake camshaft to one of two discrete positions. In 1998, infinitely variable single VANOS was introduced on the BMW M62 V8 engine. The double VANOS system, which appeared on the S50B32 engine in 1996, continuously adjusts the timing of the intake and exhaust camshafts [(44)]. The maximum range of phase timing relative to the sprocket is typically 60\({}^{\circ}\)[(45)].  
In operation, the hydraulic VVT system can be vulnerable because of oil pressure fluctuation, oil quality, viscosity, and contamination. There is also a case where the phaser does not get enough oil because of a wear-induced leakage in the lubrication system [(46)]. At low temperatures, the system may not have adequate response time because of high oil viscosity, and the hydraulic VVT system cannot be activated and has to remain at its default lock position such that the cold-start performance and emissions cannot be improved [(47)]. For example, the camshaft phasing speed of the hydraulic VVT drops to about half of that of the electrical VVT and almost to zero when the operating temperature drops from 90 \({}^{\circ}\)C to 40 \({}^{\circ}\)C and \(-\)10 \({}^{\circ}\)C, respectively. For an engine cold start at \(-\)7 \({}^{\circ}\)C, the HC emissions are reduced by about one-third when replacing a hydraulic VVT with an electrical VVT.
###### Abstract
Although flexural performance could be improved by various methods, corrosion of the reinforcing steel is still a problem limiting the application of PHC piles, especially for marine structures. Corroded piles were reported on many bridges in harsh environments, which resulted in huge maintenance costs [18; 19; 20]. In order to avoid the occurrence of corrosion, the non-corrosion material FRP was tested as a substitute for steel reinforcement. [PERSON] et al. [21] tested five square piles prestressed by CFRP strands, and the development length of the CFRP strands and the driven performance were investigated. [PERSON] et al. [19] and [PERSON] [20] investigated the life-cycle cost of CFRP piles. Compared with steel-reinforced piles, the increased initial cost could be recouped within twenty years and there would be a major saving after twenty years. Spun PHC pile is considered to have a denser micro-structure and lower permeability compared to vibrated concrete; however, there is still a high risk of corrosion due to cracks exerted during its service life [22; 23; 24; 25]. Other than ordinary steel, there are various materials used as reinforcement in concrete structures, such as FRP and shape memory alloys [26; 27; 28]. Since CFRP has been proven to be effective in the flexural reinforcing of concrete components [29; 30; 31; 32; 33; 34; 35; 36], there is a great possibility that CFRP can significantly improve the flexural performance of spun PHC piles and eliminate the risk of corrosion. However, there is very limited research on flexural performance of spun PHC with CFRP. This paper presents a comprehensive investigation on flexural performance of spun PHC piles prestressed by CFRP rods including experimental tests of 3 full-scaled specimen and a numerical parametric study. The numerical model was verified against the experimental results, and parameters including the prestressing level, reinforcement ratio and CFRP modulus were investigated. In addition, a simplified design formula was proposed based on the parametric study. The presented work can significantly promote the application of prestressed CFRP and help improve the durability of pile foundations.
# A Sector-Matching Probability Hypothesis Density Filter for Radar Multiple Target Tracking
## 4 Simulations
### False Alarm Rate and Detection Probability  
With other radar parameters kept constant, we simulated and analyzed the variation in the false alarm rate and detection probability with accumulation time for several specific false alarm probabilities. For radar MTT, a lower false alarm rate and higher detection probability is desired.  
As shown in Figure 4, reducing the constant false alarm detection threshold (i.e., increasing the false alarm probability) can raise the detection probability, but it also leads to an increase in the false alarm rate. As the beam dwell time increases, the detection probability increases and the false alarm rate decreases. Therefore, to improve the performance of radar MTT, a suitable choice is to extend the accumulation time.  
In the following simulation presented in this paper, the false alarm probability of the radar is set to \(P_{\text{fa}}=0.3\), and it can be seen from Figure 4 that \(\lambda=104\) and \(p_{D,k}=0.8\) at \(T_{i}=2\) ms, and \(\lambda=52\) and \(p_{D,k}=0.96\) at \(T_{i}=4\) ms.  
Figure 4: Variation in false alarm rate and detection probability with accumulation time with different detection probabilities for the given radar in the same scenario.
# A Real-Time Sound Field Rendering Processor
## 2 HO-FDTD Algorithm  
The HO-FDTD algorithm, a hardware-oriented FDTD algorithm proposed for real-time sound field rendering in our previous work [18], was applied as the rendering algorithm in this research. In the HO-FDTD algorithm, different formulas are applied to calculate the sound pressures of grids.
## 2 Materials and Methods
### Dataset: Simulation  
The dataset comprises Signal-to-Noise Ratio (SNR) measurements calculated every 20 ms. SNR is computed by comparing the received signal power to the noise power in the channel. The efficiency of a telecommunications system model operating in an urban microcell indoor environment was examined in this work. A frequency of 28 GHz was used to generate the SNR values in the dataset. The parameters for the environment setup used for the simulation are as shown in Table 1. The parameters are self-explanatory.  
The large-scale path loss model used in NYUSIM is a Close-In free space reference distance (CI) model with a 1 m reference distance [32]. It includes an extra attenuation term due to various atmospheric conditions. The model is given by Equation (1).  
\[PL^{CI}(f,d)[dB]=FSPL(f,1m)[dB]+10 nlog_{10}(d)+AT[dB]+\chi\sigma, \tag{1}\]  
where \(PL^{CI}(f,d)[dB]\) is the path loss in dB at a distance of d meters and carrier frequency of f GHz;  
\(FSPL(f,1m)[dB]\) is the free space path loss in dB at a distance of 1 m and carrier frequency of f GHz;  
\(n\) is the path loss exponent (n = 2 for free space);  
\(AT[dB]\) is the total atmospheric absorption term;  
\(\chi\sigma\) is the shadow fading (SF) that refers to the signal attenuation due to obstacles in the Line of Sight, modeled as a log-normal random variable with zero mean;  
\(\sigma\) is the standard deviation in dB.  
The Free Space Path Loss (FSPL), an idealized theoretical concept that refers to the attenuation of radio signal strength as it travels through space, with no obstacles or reflections, is given by Equation (2).  
\[FSPL(f,1m)[dB]=20 log_{10}(\frac{4\pi f\times 10^{9}}{c})=32.4[dB]+20 log_{10}(f), \tag{2}\]  
where \(c\) is the speed of light.  
The path loss exponent is a parameter that describes how the path loss increases with distance. For free space, the path loss exponent is 2. However, the path loss exponent can vary depending on the environment. For example, in urban areas, the path loss exponent is typically greater than 2 due to the presence of buildings and other obstructions. The total atmospheric absorption term is a measure of the attenuation of the signal due to absorption by the atmosphere. The absorption is caused by the interaction of the radio waves with the molecules in the atmosphere. The absorption is frequency-dependent, with higher frequencies being absorbed more than lower frequencies [33].  
Shadow fading is a random variation in the received signal strength due to changes in the propagation environment. Shadow fading is caused by changes in the terrain, buildings, and other objects between the transmitter and receiver. Shadow fading is typically modeled as a log-normal random variable [29] as can be seen from Equation (1).  
The large-scale path loss model is used to predict the received signal strength at a given distance from the transmitter. The model can be used to design wireless networks and to estimate the coverage area of a wireless network [33].
# Adaptive Virtual RSU Scheduling for Scalable Coverage under Bidirectional Vehicle Traffic Flow
## 6 Performance Evaluation
### Cache Replication  
In this section, we will evaluate our proposed solution with other cache replication strategies in the simulation environment. We consider the Top-K strategy (i.e., the RSUs are replicated with the most popular k replicas.), and the uniform distribution strategy (i.e., the replicas are replicated with equality possibility.) for comparison.
## 4 Conclusions  
In this paper, a flapping-wing rotor model is manufactured with two-stage reduction gear. The gear ratio is set as 22.75:1. By using the angle limiter and the stop blocks, the flapping-wing rotor can realize a variable rigid twisting angle during the downstroke and upstroke. Then, an investigation is conducted into the effect of the average stroke angle on the lift, motion, and efficiency of the FWR by an experiment. In the experiment, by taking the zero average stroke angle cases as the baseline, the effect of the positive (negative) average stroke angle on the lift generation is studied. A CFD model is also built up to calculate the FWR's numerical lift to further demonstrate that the positive effect of the positive average stroke angle on the FWR's lift observed in the experiment is an inevitable result from the perspective of aerodynamics. From the experimental study, the following remarks are drawn:  
* Compared with the cases in Cases 2 (\(\phi\in[-35,35]\)), the cases in Cases 1 (\(\phi\in[-20,50]\)) or Cases 3(\(\phi\in[-50,20]\)) share a relatively higher rotary speed given the same input voltage. The rotary speed for Case 3-8 (7 rev/s) are 1.3 times larger than that for Case 2-8 (5.375 rev/s).
* The positive average stroke angle in Cases 1 leads to the largest lift-to-power ratio (about 1.25 times those in Cases 2 and about 1.6 times those in Cases 3). The negative average stroke angle cases tend to generate the smallest lift-to-power ratio despite the negative average stroke angle facilitating the generation of a higher rotary speed.
* Through the time history curves of the lift in Case 1-6, Case 2-5, and Case 3-5, it is found that under the same flapping frequency, the peak inertial forces under different average stroke angles are similar with each other. Moreover, despite there being an apparent negative lift during the upstroke in Case 3-5 (negative average stroke angle), the instantaneous lift in Case 1-6 and Case 2-5 is positive or nearly zero.
* Whatever the input voltage is, the average lifts in Cases 1 (\(\phi\in[-20,50]\)) are about 1.25 times those in Cases 2 (\(\phi\in[-35,35]\)) and about 1.5 times those in Cases 3 (\(\phi\in[-50,20]\)).
* Among all the cases in this paper, the highest lift-to-weight ratio reaches 1.07, which means the flapping-wing rotor can realize vertical take-off.  
Above all, the positive average stroke angle will not only facilitate the increase of the rotary speed but also benefit the FWR's lift efficiency.  
Formal analysis, J.H. and Y.H.; Investigation, S.G.; Data curation, M.T.; Writing--original draft, S.C.; Writing--review & editing, L.W. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the Natural Science Foundation of Zhejiang Province (Grant No. LQ22A020006); the Science and Technology Project of Jiangxi Education Department (Grant No. GJJ[200452]); the Basic Public Welfare Research Program of Wenzhou (Grant No. G20210007); and The National Natural Science Foundation of China (Grant No. 11972079).  
Not applicable.  
The authors declare no conflict of interest.