esa-sceva/satcom-chunk-collection huggingface dataset:
# Optical Code Construction of 2D Spectral/Spatial BIBD Codes for SAC-OCDMA Systems
###### Abstract  
Optical code division multiple access (OCDMA) shows limitations in terms of the inefficient bandwidth utilization and low spectral density with one-dimensional (1D) codes. To overcome these limitations, a novel design is presented using a two dimensional (2D) spectral/spatial multiwavelength coding scheme. The proposed code is constructed using a 1D balanced incomplete block design (BIBD) technique. Theoretical and analytical results indicate that the proposed code provided improvement in the number of simultaneous users, code construction, and cross-correlation and minimized noise. Moreover, the bandwidth requirements can be minimized, and it can provide flexibility in addressing code sequences. Finally, results were compared with existing spectral-spatial 2D codes such as diagonal eigenvalue unity (DEU) and 2D diluted perfect difference (DPD). It was observed that the 2D-BIBD code fulfilled optical transmission needs with minimum effective source power (Psr = \(-\)27.5 dBm) when compared to 2D-DEU (\(-\)26.5 dBm) and 2D-DPD (\(-\)25.5 dBm) codes. Overall, our results suggested that the performance of BER for the proposed code was 72% and 22% higher than the existing 2D-DPD and 2D-DEU codes, respectively.  
spectral/spatial; balanced incomplete block design; spectral efficiency; phase induced intensity noise (PIN); cardinality; OCDMA
# Dynamic Behavior Analysis and Stability Control of Tethered Satellite Formation Deployment
## 5 Stability Analysis of TSS Deployment Using Floquet Theory  
Floquet theory is used to analyze the stability of solutions of linear ordinary differential equations with periodic variable coefficients. Local stability of deployment along preassigned pitch angles and roll angles can be analyzed by using Floquet theory. Tether length remains unchanged once the non-dimensional tether length equals one after accomplishing deployment in Section 4.2. Steps of Floquet theory applied to TSS systems are shown as follows.  
In the case of \(p_{1}=\theta,\ p_{2}=\theta^{\prime},\ p_{3}=\phi,\ p_{4}=\phi^{\prime}\), the matrix form of Equations (15)-(17) can be summarized as follows:  
\[\mathbf{P}=\left[\begin{array}{c}p^{\prime}_{1}\\ p^{\prime}_{2}\\ p^{\prime}_{3}\\ p^{\prime}_{4}\end{array}\right]=\left[\begin{array}{cc}\theta^{\prime}\\ 2(\theta^{\prime}+1)(\frac{\epsilon\sin\
u}{\kappa}+\phi^{\prime}\tan\phi)- \frac{3}{2\kappa}\sin(2\theta)\\ \phi^{\prime}\\ \frac{2\phi^{\prime}\sin\
u}{\kappa}-\frac{1}{2}[(\theta^{\prime}+1)^{2}+ \frac{3}{\kappa}\cos^{2}\theta]\sin(2\phi)\end{array}\right] \tag{30}\]  
where \(\mathbf{p}=(\theta,\ \theta^{\prime},\ \phi,\ \phi^{\prime})^{\mathsf{T}}\) are state-space vectors, and \(\mathbf{p}_{s}=(\theta_{s},\ \theta^{\prime}_{s},\ \phi_{s},\ \phi^{\prime}_{s})^{ \mathsf{T}}\) are equilibrium points, \(\theta^{\prime}_{s}=\frac{\mathrm{d}\theta_{s}}{\mathrm{d}\
u}\). Equation (30) can be expressed as follows:  
\[\mathbf{\Phi}^{\prime}=\mathbf{A}(\mathbf{p}_{s})\mathbf{\Phi} \tag{31}\]  
where \(\mathbf{A}(\mathbf{p}_{s})\) is the Jacobian matrix of vector function, \(\mathbf{P}\), in a small neighborhood  
expected in-plane angle lies outside the domain of stability. A similar result is achieved with \(e\in(0,\ 0.5)\).
# Mobile Networks and Internet of Things Infrastructures to Characterize Smart Human Mobility
## 5 Cellular Networks Technologies
### User Mobility and Data Rates  
All technologies mentioned in Section 5 capture information about user travel at any mobility profile (i.e., fixed or pedestrian). Figure 8 shows that x-axis indicate data rates supported by different cellular access standards and y-axis refers to nature of mobility of the user. Besides, in this visual comparison, we can see that all technologies support high-speed networking. From 1G to the recent 5G, users in fixed and pedestrian profile offer increased data rates, whereas in wi-fi, better data rates are possible but serve only pedestrian users.  
Nonetheless, certain challenges in the cellular network technologies and Internet of Things still remain that concern mostly the data rate greater, accessibility, mobility, and reliability. The business aspect of these technologies is flourishing and promising as were the previous generations. In other words, they will be financially beneficial to the economy no matter how successful its technical aspects become. Step by step, users will have to update their devices, or they will have to purchase a device that is compatible with these communication technologies, which produces a high financial turnover for the telecom industry and revives this business every decade. However, the telecom community's experience shows that the success of each new generation will be achieved more slowly on a step-by-step basis than the success of its business aspects.
## 2 Materials and Methods
### SPME and Chemicals  
SPME fibers of stable flex coated with divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS, 50/30 \(\upmu\)m) or PDMS (polydimethylsiloxane) were purchased from Supelco (Oakville, ON, Canada). All other chemicals, volatile standards and sugars were purchased from Sigma Aldrich (St. Louis, MO, USA).
# A Systematic Analysis of Narrowband IoT Quality of Service
## 4 Results  
In this section, the measurement results are presented and analyzed in terms of physical and application layer QoS. For each evaluation, the measurement procedure is described. Afterwards, the observations are discussed, and an initial conclusion is drawn.
## 2 Function of Factsage Software
### EpH Module  
The EpH diagram, also known as the Pourbaix diagram, uses the electrode potential of a given element as the vertical coordinate and the pH of an aqueous solution as the horizontal coordinate to predict the morphology and conditions for the stable presence of a certain element in an aqueous solution system of a specific potential and pH [66; 67; 68]. The EpH module in Factsage can be used to plot isothermal potential Eh versus acidity pH for 1-3 metals. Figure 1 shows Pourbaix diagrams of the Cr-H\({}_{2}\)O system at 298.15 \({}^{\circ}\)C, as plotted by Factsage. The figure shows the presence of heavy metal Cr in an aqueous solution under different pH and potential conditions. It can be used to determine the likelihood of the reaction of Cr to proceed under given conditions and provide a reference basis for the removal of heavy metals from the aqueous environment.  
These Pourbaix diagrams are valuable for analyzing metal morphology changes and their mechanisms in various fields such as metal corrosion, f  
Figure 1: Pourbaix diagrams of the Cr-H\({}_{2}\)O system at 298.15 \({}^{\circ}\)C.  
als [69; 70; 71; 72]. Table 3 shows examples of the application of the EpH module by researchers in various fields.  
The findings of the study conducted by [PERSON] et al. [73] demonstrates the usefulness of the EpH module in predicting and understanding the corrosion tendencies of metallic materials in different environments, which can have significant implications in the environmental field to combat heavy metal pollution and to study the forms of heavy metals in aqueous solution under different conditions. The module's ability to accurately predict the form of metallic elements in solution makes it a valuable tool for studying the corrosion resistance of alloys and the nature of metalized ions dissolved in water [75; 76; 77]. Additionally, in the field of environmental science, the module has significant applications. Heavy metal pollution is a serious threat to both the environment and human health, and efforts are being made to prevent and control it. The module can predict the forms of heavy metals present in aqueous solutions under different conditions, which can help determine the potential harm and transfer pathways of heavy metals, providing a theoretical foundation for controlling heavy metal pollution. For example, [PERSON] et al. [74] used the EpH module to determine that trivalent chromium is the predominant form of chromium in the leachate. However, over time, trivalent chromium may oxidize to hexavalent chromium, which poses ecological risks. Therefore, it is important to monitor the oxidation of trivalent chromium by dissolved oxygen in water during long-term leaching processes.
## 4 Discussion and Conclusions
Our results indicate the ability of GPR assisted by the developed signal processing approach to identify shattered rock masses, which require reinforcement strategy to increase stability, and this non-destructive technology can monitoring the surrounding rock conditions during cavern operation. The end effects of EEMD would affect deepest signals, marked as red rectangles in Figures 9, 17 and 19, and therefore the GPR time window should be at least 10% larger than the targeted depth in further applications. We also want to mention that this research only identifies the fissure interfaces inside the single-type rock formation (granite). Different types of rock formations can determine the rock strength that also influences the surrounding rock stability. Further research is planned in following aspects: Firstly, we will discover the quantity relationship between rock quality and GPR radargrams; secondly, we will investigate the signal processing approach to identify the rock stability with different types of rock formations; thirdly, we will investigate the quantity relationship between rock strengths with different types of rock formations and GPR signal features. **Author Contributions:** Conceptualization, Y.J. and Y.D. ; methodology, Y.J. ; software, Y.J. ; validation, Y.J. and Y.D. ; formal analysis, Y.J. and Y.D. ; investigation, Y.J. and Y.D. ; writing--original draft preparation, Y.J. ; writing--review and editing, Y.D. and Y.J. ; visualization, Y.J. ; supervision, Y.D. All authors have read and agreed to the published version of the manuscript. **Funding:** This research received no external funding. **Acknowledgments:** [PERSON], [PERSON], and [PERSON] in Hydraulic Engineering, Tsinghua University have kindly provided help in this research. The authors thank [PERSON] for cooperation in data acquisition as well as agreement to publish the data. [PERSON]'s work on managing the instruments and experiments is appreciated. The authors thank [PERSON] for programming support. **Conflicts of Interest:** The authors declare no conflict of interest.
# Common-Mode Voltage Analysis and Reduction for the Quasi-Z-Source Inverter with a Split Inductor
## 6 Conclusions  
A CMV reduction strategy is proposed in this paper by splitting the input inductor to make the CMV reduction strategies for the conventional VSI available for the qZSI system. With the proposed strategy, the input inductor is divided into two parts at the positive and negative side of the input source with the same total inductance, keeping the continuous characteristics of the qZSI system. The ratio of the divided two-part inductance is related to the switching vectors that are chosen, which are generally used to reduce the CMV. The average CMV during the non-ST state is used to derive the proportional relationship between the divided inductance. With the proposed strategy, the output features are not affected, while the amplitude of the CMV is reduced. Simulations and experimental results are provided to verify the effectiveness of the proposed CMV reduction strategy. Moreover, the proposed CMV reduction strategy can also be used for other converters with a similar structure to reduce the CMV.  
Figure 10: Experimental results of the CMV \(v_{\rm{CMV}}\), output voltage \(v_{\rm{out}}\) and output voltage \(i_{\rm{out}}\) when the RSPWM strategy, i.e., all even vectors in this paper, is used in (**a**) the conventional three-phase qZSI system and (**b**) the modified three-phase qZSI system [Time (\(10\,\rm{ms}/\rm{div}\))].  
Figure 9: Photograph of the experimental setup of the three-phase qZSI system.  
**Author Contributions:** Conceptualization, W.L., Y.Y. and T.K.; methodology, validation and formal analysis, W.L.; writing, review and editing, W.L., Y.Y., T.K., E.L., D.V. and F.B. All authors read and agreed to the published version of the manuscript.  
**Acknowledgments:** This research was supported in part by the Estonian Research Council (project PUT1443).  
**Funding:** This research received no external funding.  
**Conflicts of Interest:** The authors declare no conflict of interest.
## 3 Results
### Utilization of IFNAR1 Antibodies Enhanced RABV Production in MRC-5 Cells  
The IFN-\(\alpha\)/\(\beta\) receptor IFNAR1 mAbs \(\alpha\)/\(\beta\)-IFNAR1 and \(\alpha\)-IFNAR1 [30] were used to confirm the inhibition of RABV production by IFN in MRC-5 cells. The \(\alpha\)/\(\beta\)-IFNAR1 mAb binds to both IFN-\(\alpha\) and the IFN-\(\beta\) binding domain of IFNAR1, whereas \(\alpha\)-IFNAR1 mAb only binds to the IFN-\(\alpha\) binding domain. The antibodies were incubated with cells 2 h before viral infection, and then endogenous IFN-\(\alpha\), IFN-\(\beta\), and OAS1 mRNA expression was examined by qRT-PCR at 24 hpi. The MRC-5 cells treated with \(\alpha\)/\(\beta\)-IFNAR1 mAb showed a 60% reduction in the expression of IFN-\(\beta\) mRNA and an 80% reduction in the expression of OAS1 mRNA compared with the untreated cells (Figure 3A). On the contrary, the treatment of \(\alpha\)-IFNAR1 mAb did not affect the expression of OAS1, as the virus infection did not activate the expression of IFN-\(\alpha\) (Figure 3B). Additionally, the viral RNA and titer at 168 hpi in the culture supernatant were tested by qRT-PCR and FFU assays. The MRC-5 cells treated with \(\alpha\)/\(\beta\)-IFNAR1 mAb showed a significant enhancement in  
Figure 2: Treatment with IFN inhibitors enhanced RABV production in MRC-5 cells.MRC-5 cells were infected with the PM RABV strain at an MOI of 0.05. Vero cells were infected with the \(\alpha\)G RABV strain at an MOI of 0.001. The MRC-5 cells were treated with 4 uM TPCA-1 or ruxolitinib 2 h before RABV infection. **(A)** Total RNA from cells was extracted at 24 hpi, and the expression of IFN-\(\alpha\), IFN-\(\beta\), STAT1, IRF7, and OAS1 was detected by qRT-PCR. RABV mRNA expression, antigen G concentration, and viral titer in culture supernatant were measured by qRT-PCR **(B)**, enzyme-linked immune-sorbent assay (ELISA) **(C)**, and focus-forming unit (FFU) assays **(D)**, respectively, at 96, 168, and 240 hpi. \({}^{*}\): RABV infection; \({}^{*}\)\(p<0.05\); \({}^{**}\)\(p<0.01\), \({}^{***}\)\(p<0.001\); \({}^{***}\)\(p<0.0001\); \({}^{***}\)\(p<0.0001\); \({}^{*}\)\(p<0.0001\); \({}  
RABV production (Figure 3B,C). \(\alpha\)-IFNAR1 mAb treatment also showed an enhancement in RABV production. These results also indicated that the production of RABV is significantly enhanced in MRC-5 cells by the inhibition of IFN signaling pathway gene expression.
# Atmospheric GNSS RO 1D-Var in Use at UCAR: Description and Validation
## 2 Materials and Methods
### The UCAR 1D-Var
#### 2.2.2 Observation Operators
The control vector's elements used in this step are a temperature profile (covering the entire height range), a profile of the pseudo (in reference to the background temperature) relative humidity (<30 km), and the pressure at the lowest height. This step constrains the state variables so that the virtual temperature and pressure are in hydrostatic balance, and the moisture remains non-negative and sub-saturated. The essence of this two-step approach lies in that the data inversion problem is broken down into separate well-defined minimization problems in which the observation and the solution reside in the same coordinate all the time, circumventing the transform between the height and the refractional radius--and the uncertainty involved--during each minimization. Hereafter, the first minimization step is referred to as _refractivity inversion_ and the second as the _retrieval step_.
## 3 Stress Estimation Based on the Monitored Strain  
### Establishment of the Forward Model  
The forward model, which plays an important role in inverse analysis [21], can be built according to the stress-strain relationship of concrete. The structural strain is made up of four components: the elastic instantaneous strain, creep strain, shrinkage strain, and temperature strain [22], as shown in Equation (6). Of the four components, the elastic instantaneous and creep strains are dependent on the stress, and they change with the variations in the stress. The shrinkage and temperature strains are independent of the stress, but they have a relationship with the stress when the structural partition is constrained:  
\[\varepsilon_{M}=\varepsilon_{e}+\varepsilon_{c}(t)+\varepsilon_{s}(t)+ \varepsilon_{T}, \tag{6}\]  
where \(\varepsilon_{M}\) is the total strain, which can be obtained by structural monitoring, and \(\varepsilon_{e}\), \(\varepsilon_{c}(t)\), \(\varepsilon_{s}(t)\), and \(\varepsilon_{T}\) are the elastic instantaneous strain, creep strain, shrinkage strain, and temperature strain, respectively.
## 4 Experimental Results  
### IVR Fashion Show  
The important elements realized in the IVR fashion show include 3D avatar models, animations, 2D UI, and digital clothes. We utilized several software tools to create them due to their popularity and commercial support. The 3D model and 2D UI, such as the avatar, were produced manually using Autodesk and Adobe graphic tools [29; 30], and the animation of the avatar was converted to data by recording the runway walking motion of the fashion show model with the motion capture system [31]. Digital clothes were produced by the design tool Marvelous Designer [24], and the movement of the fabric was reproduced through the physical simulator of Unity game engine [25]. The data for each element were integrated in Unity together with the UI composed of the POV, clothing, effect, and sound for interaction and ported to VIVE HMD [32]. Figure 7 shows the results of the data used in the production process of the IVR fashion show.  
Figure 7: Asset data used for IVR fashion show: (**a**) 3D models (file format: OBJ), (**b**) animation (file format: FBX), (**c**) images for UI and textures (file formats: PNG, TGA, and PSD), and (**d**) clothing simulation (file format: ABC).  
The user needs to learn the control of UI beforehand through the tutorial mode of the content, because the change in scene according to the selection on the UI provided in the IVR fashion show will affect the UX evaluation. As for the change in POV, the point of view of looking at the avatar by the user wearing the HMD changes in real time. These changes are comprised of zoom in and out along with the four directions of front, left, right, and rear sides. As for the change in clothing, the clothing worn by the avatar changes in real time, but it does not directly affect the animation of the avatar on the runway stage. As for the change in effect, the falling effect of small particles is produced in real time along with the turning on and off of the background illumination. These changes are repeated in units of seconds, making the visual effect look natural. As for the sound, various background sounds were played, and the sound level was adjusted according to the location of the avatar. Figure 8 shows the change in scene according to the selection on the UI of the IVR fashion show. The accompanying video is shown in Supplementary Materials.
# Modeling and Spatial Diversity-Based Receiving Improvement of In-Flight UAV FSO Communication Links
## 5 Conclusions  
An in-flight UAV FSO communication channel model has been established. In addition to the atmospheric turbulence and UAV's jitter caused by its motor vibration, the tilt angle and the horizontal lateral wind resistance caused by UAV's different motion states have also been considered. Besides, the results of FSO communication processes under different flight states (hover state, flight state, and static state) have been compared. Analysis results show that when the BER is required to reach \(10^{-5}\), the SNR should be increased from 13 dB to 20 dB when the tilt angle of the UAVs increases from 0 to 5 mrad. With the requirement of the average BER reaching \(10^{-5}\), the SNR should be 15 dB, 17 dB, and 20 dB when the variance of the wind \(\sigma_{R}^{2}\) is 0, 1, and 2 mrad, respectively. It is verified that the spatial diversity receiving technology can effectively improve the communication quality between UAVs. If the spatial diversity array with four receivers is used, the BER of lower than \(10^{-5}\) can be obtained just with a SNR of 13 dB.  
[PERSON] contributed to the paper in methodology, program, visualization, data analysis and paper draft. [PERSON] contributed to the paper in investigation, resources and project administration. [PERSON] contributed to the paper in conceptualization, supervision, review and editing. All authors have read and agreed to the published version of the manuscript.  
Not applicable.  
The author acknowledges the valuable comments of the reviewers.  
The authors declare no conflict of interest.
# Complexity of Hamiltonian Cycle Reconfiguration
## 1 Introduction
### Our Contribution  
In this paper, we show that the Hamiltonian cycle reconfiguration problem is PSPACE-complete, even for chordal bipartite graphs, strongly chordal split graphs, and bipartite graphs with maximum degree \(6\). Our reduction for PSPACE-hardness follows from the reduction by [PERSON] (2007) for proving the NP-hardness of the Hamiltonian cycle problem for chordal bipartite graphs. However, while [PERSON] shows a polynomial-time reduction from the satisfiability problem, we show a reduction from the nondeterministic constraint logic problem ([PERSON], 2007), which is used to show the PSPACE-hardness of some reconfiguration problems ([PERSON], 2007; [PERSON], 2008).  
Unit interval graphs form a proper subclass of strongly chordal graphs, and bipartite permutation graphs form a proper subclass of chordal bipartite graphs (See ([PERSON], 2008) for example). A Hamiltonian cycle of a unit interval graph and a bipartite permutation graph can be obtained in linear time ([PERSON], 2008; [PERSON], 2008; [PERSON], 2008). On the positive side, we show that, for any two Hamiltonian cycles of a unit interval graph and a bipartite permutation graph, there is a sequence of switches transforming one cycle to the other. Moreover, we show that such a sequence can be obtained in linear time. In order to show these results, we introduce the _canonical Hamiltonian cycle_ (_canonical cycle_ for short) of a unit interval graph and a bipartite permutation graph, using vertex ordering characterizations of these graphs ([PERSON], 2008; [PERSON], 2008). We then show that each Hamiltonian cycle of a unit interval graph (resp. a bipartite permutation graph) can be transformed into the canonical cycle with at most \(n-2\) switches (resp. at most \(n-3\) switches), where \(n\) is the number of vertices of the graph. It follows that, for any two Hamiltonian cycles of a unit interval graph (resp. a bipartite permutation graph), there is a sequence of at most \(2n-4\) switches (resp. at most \(2n-6\) switches) from one cycle to the other.