esa-sceva/satcom-chunk-collection huggingface dataset:
# A Model-Free Online Learning Control for Attitude Tracking of Quadrotors
## 4 Validation
### Comparative Simulation
#### 4.1.2 Scenario 2: With Angular Velocity Measurement Noise  
In this scenario, not only external disturbances but also angular velocity measurement noise are acting on the quadrotor. For the consideration of engineering applications, the noisy angular velocity measurement \(\mathbf{\omega}_{m}\) is modeled as follows:  
\[\mathbf{\omega}_{m}(t)=\mathbf{\omega}(t)+\mathbf{w}(t) \tag{34}\]  
where \(\mathbf{w}(t)\in\mathbb{R}^{3}\) is the angular velocity sensor noise, modeled as zero-mean Gaussian random variables, with variance matrix \(\mathbf{\Sigma}_{\mathbf{w}}=\text{diag}(0.0025,0.0025,0.001)\).  
Figure 3a-c show the simulation results for attitude angle, angular velocity, and control input torque, respectively. The attitude transient-response specifications and steady state RMSEs from 10 to 100 s are listed in Tables 4 and 5, respectively.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multicolumn{2}{c}{**Specifications**} & \multicolumn{1}{c}{**MFOLC**} & **OLC** & **Units** \\ \hline \multirow{3}{*}{Maximum overshoot} & Roll & 1.88 & 2.0 & \\  & Pitch & 0.93 & 0.98 & \% \\  & Yaw & 3.59 & 3.69 & \\  & Roll & 3.2 & 4.145 & \\  & Pitch & 3.07 & 3.79 & s \\  & Yaw & 3.08 & 3.745 & \\ \hline \hline \end{tabular}
\end{table}
Table 4: Attitude transient-response specifications with angular velocity measurement noise.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline  & **MFOLC** & **OLC** & **Units** \\ \hline roll angle error & 2.3508 & 40.1740 & \\ pitch angle error & 2.2847 & 9.0077 & \(10^{-12}\) degree \\ yaw angle error & 4.5797 & 23.1220 & \\ \(\omega_{c,1}\) & 0.4892 & 35.8330 & \\ \(\omega_{c,2}\) & 0.1774 & 22.4560 & \(10^{-12}\) degree/s \\ \(\omega_{c,3}\) & 5.5551 & 15.3720 & \\ \hline \hline \end{tabular}
\end{table}
Table 3: Steady state RMSE without measurement noise.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline  & **MFOLC** & **OLC** & **Units** \\ \hline roll angle error & 0.1624 & 0.1706 & \\ pitch angle error & 0.0821 & 0.0842 & degree \\ yaw angle error & 0.1037 & 0.1049 & \\ \(\omega_{c,1}\) & 2.2417 & 2.2601 & \\ \(\omega_{c,2}\) & 2.2424 & 2.2601 & degree/s \\ \(\omega_{c,3}\) & 0.7159 & 0.7243 & \\ \hline \hline \end{tabular}
\end{table}
Table 5: Steady state RMSE with angular velocity measurement noise.  
Comparing the simulation results in Section 4.1.1, the addition of angular velocity measurement noise leads to a significant increase in the overshoot and steady state RMSE for both controllers. However, the reduced performances are still in a fine performance range.  
Overall, the comparative simulation shows that, both the MFOLC and OLC can realize attitude tracking control of the quadrotor in the presence of angular velocity measurement noise, model uncertainty and external disturbance. However, the MFOLC has better performance in terms of settling time, steady state control accuracy, and energy consumption.
## 2 Materials and Methods  
### Study Area  
Zhejiang province, China, which extends across 27.03\({}^{\circ}\)-31.18\({}^{\circ}\)N and 118.02\({}^{\circ}\)-123.17\({}^{\circ}\)E, was selected as the study area (Figure 1). The forest coverage of Zhejiang province is about 59.4%, most of which is distributed in the mountains and hills. The subtropical monsoon climate is the dominant climate of Zhejiang province; it has hot, rainy summers and cold, dry winters, and has obvious characteristics of seasonal change. The mean annual temperature of Zhejiang is between 15 and 18 \({}^{\circ}\)C, while the average annual precipitation ranges between 980 and 2000 mm. The growing season usually starts in March and ends in October. The evergreen broadleaf forests and mixed coniferous-broadleaf forests are the main vegetation types of the study area (Figure 1); there are more than thirty tree species in the forest landscapes of Zhejiang province.  
In this study, the tropical forest landscapes of Zhejiang were selected as the study area primarily for the following reasons: on the one hand, Zhejiang has a developed economy, whereby urbanization and other human activities in Zhejiang have caused drastic land use changes. In addition, Zhejiang has a large forest area and a high forest coverage; these two factors result in the distribution pattern of subtropical forests in Zhejiang containing all types of forest fragmentation, as well as having typical gradients of forest frag-mentation. On the other hand, Zhejiang has turned to the stage of ecosystem protection after its early development; the change in forest cover after 2000 is quite limited compared to that of its neighboring regions, which makes it convenient for this study to compare the productivity and its trend among static fragmentation types.  
Figure 1: Location, forest type distribution, and classified forest fragmentation levels of forest landscapes in Zhejiang, China. **(a)** The location of Zhejiang, China. **(b)** Distribution of main forest types in Zhejiang. **(c)** Forest fragmentation levels in Zhejiang. UNC: unclassified forest, PAT: patch forest, TRA: transitional forest, PER: perforated forest, UND: undetermined forest, EDG: edge forest, INT: interior forest. The forest type data were derived from the MODIS MCD12Q1 land cover product (from 2010), while the map of fragmentation levels was calculated using the forest fragmentation model (see Section 2.2) in this study.
# Design of Novel Laser Crosslink Systems Using Nanosatellites in Formation Flying: The VISION
## 4 Laser Crosslink Payload  
### Payload Architecture  
The laser crosslink payload has a monostatic architecture that shares communication and PAT beam paths with a single aperture. This design scheme provided closed-loop feedback FSM control without steady-state beam-pointing errors. To operate each PAT sequence, the payload has variable beam-divergence angles. In addition, the SLA of each satellite has a different wavelength, telecom optical C- and L-bands. This approach removes the primary internal reflection effects, which require making a pair of each other for crosslink establishment. Figure 9 shows the payload configurations with allocations for each part. The primary mirror is segmented into three parts, and the secondary mirror is attached to the boom deployment mechanism, thereby saving space during the launch phase. The optical components are arranged on an optical bench. The support plate acts as a mechanical interface with the bus, and the main material is Invar-36 to mitigate on-orbit thermal deformations with structural stiffness.  
Figure 9: _Cont._  
Table 6 summarizes the payload design specifications. The SLA comprises a laser with 1 mW of optical power; the EDFA amplifies the seed laser up to 1 W. Mass is approximately 5.7 kg and the power draw is less than 39.1 W, meeting the 6U standard constraints. The modulation is basically OOK, which is mostly adopted for laser crosslink systems. From the optical link budget analysis, the design parameters met the system requirements and constraints, including the SNR margin, size, and pointing accuracy. The divergence angle of the laser beam generated by SLA can be adjusted in two ways: coarse PAT (CPAT) and fine PAT (FPAT). The field of view for each detector was designed based on the bus attitude control performance and FSM tip-tilt angles. While the beam spots on each detector are located within the field of regard (FOR) or allowable tip-tilt angles, the FSM can correct them to be close to the center of the detectors.  
\begin{table}
\begin{tabular}{c c c} \hline
**Parameter** & **Specifications** & **Remarks** \\ \hline
**Data Rate** & 1 Gbps & at 1000 km \\
**Unassisted Pointing** & \textless{}\textless{}\pm\textless{}637\textless{}\textless{}\textgreater{} \textless{}
## 4 Results
### Direct Shearing Tests
[9] conducted a comparison between the improvement in a clay, similar with the one used in this study, from a site near Cluj-Napoca, with plastic waste materials and that with cement. Both materials were added in different samples in percentages of 2%, 4%, 6%, and 8%. Direct shear tests were performed on the samples made. In the case of plastic waste materials, the best results were noticed at an addition of 4%. Comparing the results on samples with 4% added cement and those on samples with 4% added plastic waste materials, it can be easily seen that the results in the case of cohesion were 52% lower for plastic waste materials than for cement, similarly for the internal friction angle (a decrease of 63%). In Table 6, the results of [PERSON] et al. [9] were compared with the results of this study, in order to analyse all the results and the influence that the addition of PET and cement has on clays from the Cluj-Napoca area. The paper of [PERSON] et al. [9] was published in the year 2017; therefore, the clay, clay + PET and clay + cement samples were named as follows: unimproved clay--Cl17; clay + 2%, 4%, and 6% PET--Cl2 PET17, Cl4 PET17, and Cl6 PET17; and clay + 2%, 4%, and 6% cement--Cl2 CEM17, Cl4 CEM17, and Cl6 CEM17. In turn, the  
Figure 6: The variation in internal friction angle for the four admixtures. Figure 7: The variation in cohesion for the four admixtures. clay and clay + PET samples obtained in year 2023 in the presented study were named as follows: unimproved clay-Cl23, clay + 2%, 4%, and 6% PET--Cl2 PET23, Cl4 PET23, and Cl6 PET23. Comparing the results in Table 6, it can easily be seen that the geotechnical results of clay improved with different percentages of cement are superior to those of clay improved with PET waste. However, it cannot be ignored that even a small addition of PET (2% and 4%) can considerably improve the mechanical characteristics of a clay. The fact that a small addition of plastic waste materials improved the shear parameters of a clay is a good result, especially considering the extremely low costs of obtaining plastic waste materials compared to those of obtaining the additive from cement. For a slight improvement in the geotechnical characteristics of a clay, the addition of PET waste can be used. This improved soil can be used for constructions with lower loads, for embankment stabilisation or for the base and subbase layer of pavements and road structures. For a greater level of improvement in the geotechnical parameters of a clay, one can switch from adding waste plastic materials to adding hydraulic binders such as cement or lime.
## 5 Future Research
### ESS for VI System  
ESS including capacitors and batteries have been proposed to integrate with VI system. It is to support dynamic frequency control using power electronic converters, in injecting or compensating active power [95]. The supercapacitor or ultracapacitor acts as temporary energy storage to tackle short-term power fluctuation for inertia emulation. It emulates the inertia of a VSG to overcome high-frequency power fluctuations. In contrast, the battery deals with the long-term power fluctuations by emulating the remaining parts of the VSG which consist of droop control and reheat turbine model. The energy storage system reduces the power fluctuations of the battery effectively with the hybrid combination of ultracapacitor and battery. It achieves better system-level frequency stability while improves frequency nadir and RoCoF [96]. ESS is crucial and important for small power network with low inertia [97]. The DC-link capacitor can be replaced by ultracapacitor with larger capacitances and better flexibility for VI emulation [98]. BESS units are well-suited to provide either fast frequency and voltage control reserves or synthetic rotational inertia for power system operation, due to their very  
Figure 15: The technical gap of VI-based inverter.  
fast response behavior. A hybrid ESS consists of a battery and ultracapacitor, where the latter tackles high-frequency power fluctuations and the former resolves low-frequency power fluctuations. It is used to implement a VSG control strategy.
# Comparison of SEVIRI-Derived Cloud Occurrence Frequency and Cloud-Top Height with A-Train Data
## 2 Materials and Methods
### Datasets
#### 2.1.1 CPR/CloudSat  
CloudSat is a satellite experiment designed to measure the vertical structure of clouds and to observe cloud and precipitation from space simultaneously with A-Train satellite constellation [16]. The primary CloudSat instrument is a 94 GHz, near nadir-looking, CPR which measures the power backscattered by clouds. CloudSat was launched in tandem with CALIPSO, a second Earth System Science Program (ESSP) mission, which is equipped with CALIOP, a dual frequency LiDAR instrument. The CPR was developed jointly by the National Aeronautics and Space Administration (NASA)/Jet Propulsion Laboratory (JPL) and the Canadian Space Agency (CSA). The overall design of the CPR has a strong heritage from many cloud radars presently in operation in ground-based and airborne applications. The CPR samples profiles at 625 kHz, correspond to a range of sampling distance of 240 m. Each profile has 125 vertical bins. One vertical profile of the atmosphere is recorded every 0.16 s by averaging approximately 600 pulses. CPR provides an instantaneous footprint of approximately 1.3 km across-track by 1.7 km along-track at mean sea level [17]. The Cooperative Institute for Research in the Atmosphere (CIRA) CloudSat Data Processing Center (DPC) generates and provides the data for subsequent level 0 (raw data) through level 2 (derived products), including radar backscatter profiles (1B-CPR), cloud geometrical profiles (2B-GEOPROF), cloud classification (2B-CLDCLASS) and other products. The data used in this study are radar backscattering profiles and CTH in 2B-GEOPROF acquired from CIRA CloudSat DPC ([[ftp://ftp1.cloudsat.cira.colostate.edu](ftp://ftp1.cloudsat.cira.colostate.edu)]([ftp://ftp1.cloudsat.cira.colostate.edu](ftp://ftp1.cloudsat.cira.colostate.edu))). CTH data were obtained from height values for 125 vertical bins and the cloud mask, indicating the presence of a cloud inside a CPR bin. The cloud mask has values of 0 for clear condition, 1 for error, 5 for ground clutter,5-10 when the bin is judged to be contaminated by clouds weakly through the along-track integration, and 20-40 when clouds are detected. A larger cloud mask value is related to a higher confidence in cloud detection. CloudSat project team suggested that vertically connected CloudSat bins with significant cloud mask values (\(\geq\)30) are regarded as a cloud layer [18]. [PERSON] et al. [19] analysed the sensitivity of CPR cloud detection to different CPR cloud mask values compared with CALIOP observations. In this study, CPR CTH is defined as a layer at the point where the accumulated value from the top downward becomes larger than 30 as defined by the AVAC-S software.
## 3 Study Area and Data
### Research Data Acquisition and Processing
#### 3.2.3 Streetscape Image Data Acquisition  
In this study, we utilize the street view image data provided by the Tencent Street View platform to extract street-level road environment features. By analyzing the road network data, we selected a total of 8044 street view sampling points with an average sampling interval of about 100 m. Four images were captured at each sampling point with orientations of 0\({}^{\circ}\), 90\({}^{\circ}\), 180\({}^{\circ}\), and 270\({}^{\circ}\), constituting a 360\({}^{\circ}\) panoramic view to fully characterize the environment at each sampling point. We acquired a total of 32,176 street view images of Hong Kong's Kowloon Peninsula, each with a size of 1024 \(\times\) 1024 pixels. The final sampling point location map and the acquired street view images are shown in Figure 12, with the green nodes representing the street view sampling points.
# Crouch Gait Analysis and Visualization Based on Gait Forward and Inverse Kinematics
## 2 Materials and Methods
### Gait Forward Kinematics
#### 2.1.1 Quaternions Algebra for Rotations  
A quaternion can be expressed into the \(\mathbb{H}\) four-dimensional space as \(\mathbb{H}:=\mathbb{R}+\mathbb{R}\mathbf{i}+\mathbb{R}\mathbf{j}+\mathbb{R} \mathbf{k}\), where \(\mathbf{i}=(1,0,0)\), \(\mathbf{j}=(0,1,0)\) and \(\mathbf{k}=(0,0,1)\) are called the principal imaginaries and obey [PERSON]'s rules, i.e., \(i^{2}=j^{2}=k^{2}=ijk=-1\). Multiplication of these imaginaries resembles a cross-product \(ij=k,jk=i,ki=j,ji=-k,kj=-i,ik=-j\). A quaternion \(Q=r+xi+yj+zk\) consists of a real part \(a=r\) and a purely imaginary part \(v=xi+yj+zk\). Quaternions with a zero real part are called pure quaternions. They can be written as \(Q=a+v\) and decomposed into \(Q=a+bu\), which resembles a complex number, where \(u=[x,y,z]^{T}/b=\frac{x}{||v||}i+\frac{y}{||v||}j+\frac{z}{||v||}k\) is a unit three-vector and \(\|u\|=1\). \(\overline{Q}=Q^{-1}=a-bu\) is known as the conjugate quaternion [30].  
Figure 1: Research framework for gait forward and inverse kinematics analysis and visualization.  
A rotation of an angle \(q\) about an axis \(u\) can be represented as the following unit quaternion:  
\[Q=\ \cos\left(\frac{q}{2}\right)+u\sin\left(\frac{q}{2}\right), \tag{1}\]  
for which the unit conjugate quaternion is  
\[\overline{Q}=\ \cos\left(\frac{q}{2}\right)-u\sin\left(\frac{q}{2}\right), \tag{2}\]  
Thus, the rotation to an arbitrary vector (pure quaternion) \(v\in\mathbb{R}^{3}\) is provided by the quaternion multiplication  
\[R(Q)v=Qv\overline{Q}. \tag{3}\]
# Repeater Insertion for Multi-Walled Carbon Nanotube Interconnects
## 1 Introduction
Therefore, closed-form expressions for the optimized repeater size and number are desirable for MWCNT interconnects with the considerations of contact resistance and inductive effects, which is the motivation behind this study. Based on the resistance-inductance-capacitance (RLC) model, this study focuses on the impacts of contact resistance on the optimal repeater size and number in intermediate- and global-level MWCNT interconnects at the 14 nm and 7 nm technology nodes. The rest of the paper is organized as follows. Section 2 introduces the ESC model of the MWCNT interconnects. Repeater insertion is studied in Section 3, with the closed-form expressions presented. Based on the proposed closed-form expressions, the optimal repeater insertion in MWCNT interconnects is investigated in Section 4. Some conclusions are finally drawn in Section 5.
## 3 Numerical Results and Discussion
### Discussion of Material Parameters and Configuration  
In cancer therapy applications, the laser wavelengths are in the biological window (800 to 1000 nm). In such a window, the imaginary part of the permittivity of the gold nanoparticles constituting the agglomerates slightly increases with the incident wavelength, necessitating the designing of the particle shapes forming the agglomerates or the decreasing of the laser power. For individual nanoparticles, our results are in agreement with the experimental ones in Refs. [3; 4; 5; 6; 7] (the absorption efficiencies, due to the shapes of the nanoparticles, are counterbalanced by smaller laser power densities, producing compatible heat sources and temperature elevations). Moreover, the treatment of larger biological media/cells (typically a cell size is varying from 1 to 100 \(\upmu\)m [32]) or a mix of smaller/larger concentrations of nanoparticles, a smaller/greater power opens the way to control both the PA efficiency (i.e., the local temperature elevation above the ablation threshold) and the protection of the neighboring region of the biological media/cells (i.e., limiting the risk of higher temperature elevation). Each nanoparticle acts as a local temperature source, and in a mixture of agglomerates of nanoparticles, multiple local thermic sources are induced simultaneously. Therefore, the global thermic field is increased and the main effect in the temperature elevation is directly related to agglomerates inducing a strong photo-thermic coupling. Therefore, as the maximum temperature is directly related to the characteristics of the agglomerates (i.e., to the size of the nanoparticles and to the number of nanoparticles participating in the agglomerate and inducing strong coupling), two configurations are to be favored: either promote the use of large nanoparticles in very low concentrations, or use small nanoparticles in high concentrations. Each of these two configurations has advantages and disadvantages, which can be minimized (e.g., adjusting the laser power) and which depend on the use conditions in real life. The use of large nanoparticles in low concentrations permits the production of an active PA with a limited risk of agglomerates exceeding the temperature limit. Conversely, the use of small nanoparticles in high concentrations limits the risk of producing an inactive PA and avoids the risk of exceeding the temperature limit.  
Figure 6: (**a**) Probability of mixed strong-coupled agglomerate as a function of the relative mass concentration \(C_{rm}\) of nanoparticles, relative to the biological media/cells. (**b**) Temperature evolution as a function of the relative mass concentration \(C_{rm}\) of nanoparticles with diameters of \(D_{np}\).
# Estimating the Fractional Vegetation Cover from GLASS Leaf Area Index Product
## 5 Discussions  
The method proposed in this study calculated TRAGL FCover values from the GLASS LAI product to ensure physical consistency between LAI and FCover retrievals. The GLASS LAI retrieval algorithm estimated the LAI annual profile using annual observations. The GRNNs used in GLASS LAI production use the surface reflectance for a one-year period as their input. The output is a one-year LAI profile for each pixel. Extensive validation and analysis demonstrated that the GLASS LAI product is spatially complete and temporally continuous, and the accuracy of GLASS LAI product is better than several existing LAI products. Therefore, the TRAGL FCover product also shows temporally continuous and smooth FCover profiles and better performance as compared to ground-based estimates.  
On the downside, the surface-reflectance data for a one-year period were entered into the GRNNs to estimate the one-year LAI profiles. The GLASS LAI retrieval algorithm is essentially a reanalysis method. It is impossible to provide near-real-time retrievals for the GLASS LAI retrieval algorithm. Therefore, the method proposed in this paper also cannot carry out real-time/near real-time estimation of FCover values because of the dependence on the GLASS LAI product.  
Additionally, the quality of the GLASS LAI product has a direct impact on the quality of the TRAGL FCover product. The GLASS LAI retrieval algorithm can remove abrupt spikes and dips, which may lead to the loss of neighboring smaller peaks in LAI profiles. Therefore, The TRAGL FCover product also cannot describe more local (in time) impacts of disturbances such as fire, disease, and insect damage.