esa-sceva/satcom-chunk-collection huggingface dataset:
## 1 Introduction
### Aims and Novelty of This Research  
Based on the results obtained in previous works [7], the aim of this research is to demonstrate the validity of a proper WW\({}_{\text{eq}}\)R schedule to better achieve both IAQ and TC, using different ventilation protocols. As described by other authors, there are interesting  
Figure 1: Main parameters affecting cross ventilation.  
possibilities for achieving IAQ without mechanical ventilation in school buildings [6; 14; 20], but they may compromise TC and EE. This depends on the climatic conditions [6; 14; 20], the envelope performance [6], set-point temperatures [14], the consideration of adaptive thermal comfort [42] and the efficiency of the mechanical systems [20]. It is necessary to elaborate window-opening management protocols that are based on natural ventilation and low-cost sensors in schools where mechanical ventilation is not an option. Then, the validation of these protocols is necessary to understand how to solve the IAQ-TC-EE Dilemma within specific climatic conditions and building configurations.  
The research aims to carry out the following:  
* Using Designbuilder simulations of this case study, obtain the WWeqR that provides enough air renovation to fulfill the CO2 levels under the required limits:
* For the steady natural ventilation protocols (SNVPs), it describes a WWeqR that allows the achievement of the required CO2 all the time.
* For the dynamic natural ventilation protocol (DNVP), it describes the functioning of the dynamic WWeqR according to the indoor CO2 sensors, to minimize the outdoor air infiltration.
* Using the monitoring data from this case study, validate the proper functioning of the WWeqR in buildings with manual operation, providing enough air renovation to fulfill the CO2 levels requested.
* Considering adaptive models, anticipate the TC outcomes that may arise due to the introduction of outdoor air without heat-recovery units.
* Provide a summary of design-and-management rules of thumb for scholar buildings in a subtropical climate to achieve acceptable IAQ during the operational time as an alternative to installing mechanical ventilation systems.  
The paper contains the following: Section 1 introduces the problem and the perspective of the research, with the objective and aims to be achieved. Section 2 describes the materials and methodology used in the research. It includes the simulation, the case study description and the proceedings and materials for the data monitoring. Section 3 shows the results for the different scenarios described in Section 2. Thus, Section 4 discusses the outcomes from the data of the preceding section. Finally, Section 5 provides the main conclusions obtained and suggests future works. Some relevant material is included in Appendices A and B.
# Towards Understanding Driver Acceptance of C-ITS Services--A Multi-Use Case Field Study Approach
## 1 Introduction
### Scope and Research Questions  
This paper presents the results of a user acceptance evaluation of C-ITS services, conducted with a heterogeneous group of 18 drivers in Austria as part of a broader impact assessment. It also includes findings from an online questionnaire completed by 95 participants. The focus lies on I2V services (see Section 1.2), which provide drivers with information about traffic-related situations and offer driving recommendations in interurban scenarios. The evaluation was carried out using real-world test drives with interviews and an online survey. Results of the evaluation were discussed using 26 relevant papers from the literature. Psychological and cognitive science aspects, however, were beyond the scope of this paper.  
The paper aims to answer the following research questions:  
1. What is the perceived level of usefulness of the specific C-ITS services (1) Road Works Warning, (2) Hazardous Location Notification, (3) In-Vehicle Signage, and (4) Routing recommendation?
2. How do users rate the perceived ease of use of the specific C-ITS services (1) Road Works Warning, (2) Hazardous Location Notification, (3) In-Vehicle Signage, and (4) Routing recommendation?
3. How do users rate the behavioural intention to use the C-ITS services (1) Road Works Warning, (2) Hazardous Location Notification, (3) In-Vehicle Signage, and (4) Routing recommendation?
4. To what extent do the findings of the current field studies align with and are supported by existing C-ITS literature?  
The paper is organized as follows: Section 2 provides an overview of the methodology used for both the user acceptance and the literature review. Section 3 presents the results of the two field studies, while Section 4 discusses the results and compares them with the results of the literature review. Section 5 concludes the paper and gives an outlook.
## 4 Incorporation of Synthetic Data  
We are able to use synthetic data obtained from equilibrium solutions to System (2) to explore parameter inference via maximum likelihood estimation. In this section, we use the same environment \(U\) and potential \(K\) as was used Figure 1. We generate synthetic data by rejection sampling. Specifically, we choose the coordinate pair \((x_{i},y_{i})\) at random from the domain and \(z_{i}\) at random from a uniform distribution on the interval \((0,1)\). If \(f(x_{i},y_{i})>z_{i}\), where \(f\) is the probability density function found from the equilibrium solution to (2), we add the data value \((x_{i},y_{i})\) to the set. We continue until we have the desired number of data points.  
Given the set of synthetic data with \(M\) data points for each of \(N\) groups, \(\{y_{i}^{m}|i=1,...N,m=1,2,...,M\}\), we minimize the negative log-likelihood function over the set of parameters, \(\theta\):  
\[-\ell(y,\theta)=-\sum_{i=1}^{N}\sum_{m=1}^{M}\log(f(y_{i}^{m}|\theta)).\]  
The probability density functions, \(f(\mathbf{x}|\theta)\), are found using the methods described in Section 3, with initial condition determined by the kernel density estimation of the set of synthetic data. We use stochastic gradient descent (SGD) to minimize the negative log-likelihood function. SGD uses one or a few data points to update the parameter at each iteration. This leads to more variance in the update, thus allowing a possibility to move away from a local minimizer. We update the parameter as follows:  
\[\theta=\theta-\alpha\
abla_{\theta}\Bigg{(}-\sum_{i=1}^{N}\log(f(y_{i}^{m}| \theta))\Bigg{)}, \tag{10}\]  
where \(m\) is a randomly chosen from the set \(\{1,2,...,M\}\), and \(\alpha\) is the learning parameter, which typically decreases with time. To keep within a stable parameter range, we have the bounds \(0.125\leq b\leq 0.44\) and \(3\leq\eta\leq 8\).
# Positioning Methods and the Use of Location and Activity Data in Forests
## 2 Types of Positioning Technologies
### GNSS - Single, Dedicated Receiver
Handheld receivers have also been used to a limited extent to quantify the productive cycle times of logging equipment [42; 43; 44; 45] and soil impacts of harvesting equipment [46; 47]. Use of single-unit GNSS to assist with navigation and to record travel  
Figure 1: The Global Positioning System (GPS) and, more broadly, the Global Navigation Satellite System (GNSS), rely on three or more navigation satellites to determine ground position of receivers. Position is determined based on the time-delay associated with signal reception relative to synchronized clocks on each satellite. GNSS devices with the capacity to integrate signals from two or more international constellations are increasingly available. The rapidly growing number of satellites generally corresponds with increasing accuracy in a wider range of devices over a 5–10 year transition period. paths for heavy equipment in forestry is now fairly common [30; 48; 49; 50]. Onboard computers and software sold by large equipment producers such as Caterpillar, John Deere, and Ponsse have built-in GNSS receivers with the ability to map equipment locations on harvest maps, showing machinery proximity to unit boundaries or streamside management zones [20]. Single-user devices have also been used for personal location, safety, and field navigation in the woods by foresters and other natural resource managers for decades. Handheld Garmin, Trimble, or other consumer-grade GNSS units have traditionally been a standard tool attached to the field vest of most foresters when they head to the woods. GNSS accuracy provided improved estimation of land area over traditional compass and pace field methods [51]. Individual GNSS receivers have become increasingly small in stature over time; what were originally backpack-worn units are now small chips that fit inside smartphones and smartwatches [29; 52]. As in forestry, use of handheld GNSS receivers has been commonplace in wildland and prescribed fire for maintaining reference position, marking waypoints of snags or other hazards, relaying coordinates of spot fires and delineating burn perimeters to determine area burned [53]. Multi-temporal burn perimeter data combined with current wind speed and direction can also provide inputs for forecasting predicted fire spread [54].
# Degree-Constrained Minimum Spanning Hierarchies in Graphs
## 5 Algorithm Design
### A Heuristic
#### 5.2.1 A Lower Bound  
Consider the following spanning tree.  
**Definition 5** (Minimum spanning tree with specified leaves--MSTSL).: _Let \(V_{1}\subset V\) be the subset of desired leaves. The MSTSL is a minimum cost spanning tree covering the node set such that the nodes in \(V_{1}\) are leaves in the tree._  
The degrees of the nodes in \(V\setminus V_{1}\) are not limited in the tree. An MSTSL in \(G\) can be computed in polynomial time as follows:  
1. Delete the nodes in \(V_{1}\).
2. Compute an MST in the remaining graph.
3. Reconnect the nodes in \(V_{1}\) to the MST using the best cost adjacent edges.  
A more complex study can be found in [19], which gives sufficient conditions for a graph to have a spanning tree with a specified set of leaves.  
Theorem 3.3: _Suppose that spanning hierarchies corresponding to the given degree constraints exist in a graph \(G\). Then, an MSTSL exists and its cost is a lower bound for the cost of any DCMSH._  
Proof.: Satisfying the conditions in Theorem 1 guarantees that there is no separator in \(V_{1}\) and the MSTSL exists. In a DCMSH \(H\), each node in \(V_{1}\) is present only once (nodes in \(V_{1}\) must be leaves in \(H\)). By deleting the leaf nodes in \(V_{1}\) and the set \(E_{1}\) of their adjacent edges from \(H\), a hierarchy \(H^{\prime}\) is obtained. The image \(I^{\prime}\) of \(H^{\prime}\) in \(G\) may contain cycles. Since a node of \(v\in V\setminus V_{1}\) can be associated with several node occurrences in \(H\) and in \(H^{\prime}\), it can have more than \(D(v)\) neighbors in the image. \(I^{\prime}\) does not necessarily respect the degree constraint. From each possible cycle in \(I^{\prime}\), an edge can be deleted and a tree \(T^{\prime}\) in \(G\) covering the node set \(V\setminus V_{1}\) is obtained (it is possible that \(T^{\prime}\) does not respect the degree constraints). By adding the deleted nodes in \(V_{1}\) using the edges in \(E_{1}\) to \(T^{\prime}\) a spanning tree \(T_{1}\) is created. It respects the constraints for the specified leaf nodes in \(V_{1}\). Since \(T_{1}\) contains the edges that are present in \(H\) only once and some edges are eventually deleted from the image \(I^{\prime}\): \(c(T_{1})\leq c(DCMSH)\). Since an MSTSL \(T_{L}\) exists and \(T_{1}\) is also a spanning tree respecting the constraints given by \(V_{1}\), \(c(T_{L})\leq c(T_{1})\). Finally, \(c(T_{L})\leq c(T_{1})\leq c(DCMSH)\).  
The main features of the proposed heuristic are as follows.  
1. An MSTSL is created.
2. The MSTSL is decomposed into a set of edge-disjoint stars.
3. A degree-constrained spanning hierarchy with low cost is computed in each star.
4. Finally, these spanning hierarchies are connected to form a unique hierarchy spanning the MSTSL. (cf. Figure 6).
# Survey on 5G Physical Layer Security Threats and Countermeasures
## 2 Technology Background of Physical Layer
### Frequency Bands in 5G
#### 2.1.5 5G IoT Technologies  
The advent of 5G technology has brought significant advancements, not only in the field of wireless personal communication but also in the domain of connected devices--IoT. IoT-based communication and related technologies, characterized by low hardware and operational cost, low power and data rate, and long range communication capabilities, have become integral into many sectors, including industry and healthcare [42]. Critical components of 5G, such as LTE Cat-M and Narrow Band IoT (NB-IoT) technologies, address the growing demand for IoT applications. These technologies are specifically designed for Low-Power Wide Area Network (LPWAN) communications [43], making them ideal for connecting a vast number of IoT devices.  
However, these advancements also introduce new security challenges, particularly at the PHY layer of communication [44]. Ensuring robust security at this layer is crucial, as it serves as the foundation for all higher-level security mechanisms. Currently, numerous studies are focusing on the security threats of IoT technologies. [PERSON] et al. [45], in their survey study, examined the Cellular IoT Service Security issues and challenges. They noted that integrating cellular IoT into existing cellular networks can lead to security vulnerabilities due to various operational differences between the cellular IoT and non-IoT devices. [PERSON] et al. [46] addressed the issue of terminal identity trustworthiness in IoT-based mobile communication, specifically targeting forgery attacks in single-package authorization and proposing a solution to handle this problem. Other studies [47; 48; 49] have explored IoT security issues and their detection using Machine Learning (ML) and Deep Learning (DEL) approaches. In [47], an ML-based IoT intrusion detection model to enhance data processing security and attack detection accuracy was developed. Survey papers [50; 51; 52] provide overviews of IoT technologies, including LTE Cat-M and NB-IoT, discussing security and vulnerability issues. Addressing these security threats is essential to protect the integrity, confidentiality, and availability of 5G networks [53], ensuring safe and reliable communication for IoT devices.
## 4 Discussion
(b) Adopting graph neural networks (GNNs) or Transformer architectures to explicitly model global spatiotemporal correlations of ionospheric parameters [30]. (c) Incorporating real-time Ne observations from low-Earth orbit (LEO) satellites (e.g., Swarm) to enhance generalization via multi-source data assimilation. Furthermore, extending the model to ionospheric disturbance propagation tracking would amplify its operational utility in space weather services.
###### Abstract  
Background: The US government has enacted the Health Insurance Portability and Accountability Act (HIPAA), in which patient control over electronic protected health information is a major issue of concern. The two main goals of the Act are the privacy and security regulations in the HIPAA and the availability and confidentiality of electronic protected health information. The most recent authenticated key-agreement schemes for HIPAA privacy/security have been developed using time-consuming modular exponential computations or scalar multiplications on elliptic curves to provide higher security. However, these authenticated key-agreement schemes either have a heavy computational cost or suffer from authorization problems. Methods: Recent studies have demonstrated that cryptosystems using chaotic-map operations are more efficient than those that use modular exponential computations and scalar multiplications on elliptic curves. Additionally, enhanced Chebyshev polynomials exhibit the semigroup property and the commutative property. Hence, this paper develops a secure and efficient certificate-based authenticated key-agreement scheme for HIPAA privacy/security regulations by using extended chaotic maps. Results and Conclusions: This work develops a user-authentication and key-agreement scheme that solves security problems that afflict related schemes. This proposed key-agreement scheme depends on a certificate-management center to enable doctors, patients and authentication servers to realize mutual authentication through certificates and thereby reduce the number of rounds of communications that are required. The proposed scheme not only provides more security functions, but also has a lower computational cost than related schemes.  
chaotic maps; HIPAA; authentication; key agreement; PHI security
# Evaluation of Forward Models for GNSS Radio Occultation Data Processing and Assimilation
## Appendix A Abel Integral Algorithms
### Spherically Symmetric Assumption  
The spherically symmetric assumption is the prerequisite of the Abel integral. The bending angle (BA) \(\alpha\) is defined as the accumulated direction change of a signal from being transmitted by the GPS to being received by a low earth satellite (Figure 11). The BA \(\alpha\) is twice the size of \(\theta\) based on the spherically symmetric atmosphere assumption. We assume the earth below the bent ray is symmetric about OC (\(r_{t}\)). If the right triangles AOC and BOC are the same, and the right triangles MOB and MAP are similar; then, \(\angle\alpha\) is twice the size of \(\angle\theta\) since they have the shared angle \(\angle\)AMP. According to [PERSON]'s law, the impact parameter \(a=nr\)sin90\({}^{\circ}\)[37; 38; 39]. The direction vector \(r\) is the same as the direction of the refractive index \(n\)'s gradient. The BA is expressed as  
\[\alpha(a)=2\int_{r_{t}}^{\infty}d\theta=-2a\int_{r_{t}}^{\infty}\frac{d\ln(n )}{dr} \tag{11}\]  
where \(nr\) is replaced with \(x\), then we have Equation (2) [23; 25; 39].  
There are two singularities in Equation (2): \(x=a\) and \(x\rightarrow\infty\). The finite upper limit is set as 120 km or 150 km (for Beidou FY3C/D) in a real-world application. The singularity of \(x=a\) can be eliminated by different analytical methods, called the Abel integral methods.
## 3 Results: Numerical Analysis
### Finite Element (FE) Model of the Nonlinear Spring  
In this section, a comparison is made between Equation (12) and the ANSYS finite element (FE) results. A beam made from aluminum with a thickness of 1 mm, a width of 16 mm, and a length of 90 mm is modeled using ANSYS, see Figure 16a. The 1 cm wide middle component, shown in Figures 15 and 16a, represents the shaft of the bottom chamber piston. The plane stress with thickness (of 16 mm) option was used in ANSYS for this FE run. The FE model of Figure 15, shown in Figure 16a, was developed using the ANSYS 2023R1 finite element software program. The FE model of Figure 16a is given a 3 mm displacement in the negative y-direction with the beam held fixed at the edges. SI units were used in the FE model and the FE analysis. The ANSYS \"Large Displacement Static\" option was turned on (NLGEOM, ON). Thirty sub-steps were prescribed, meaning at each sub-step, a motion of 0.1 mm was applied until the FE model was deformed by 3 mm. The results of all the 30 sub-step runs were saved. Figure 16b shows the beam's deformed shape at a 3 mm input displacement.  
Figure 16: _Cont._  
Figure 17 shows an excellent correlation between the ANSYS load-deflection results versus the results of using Equation (12), with the highest error being 8.1%.  
Figure 16: (**a**) ANSYS finite element (FE) model of Figure 15 (**b**) FE model deformed shaped.  
Figure 17 shows that at small deformations, the slope (stiffness) is 33,183 N/m and at high deflections, near 3 mm, the slope (stiffness) is about 506,300 N/m. A cubic stiffness equation of \(F=33,183x+1.88\times 10^{10}\)\(x^{3}\) matches the ANSYS results very well.
## 3 Results and Discussion
### Factors Investigation
#### 3.2.3 Contact Angle  
The contact angle describes the wetting ability of a liquid on a specific solid surface, which is affected by multiple factors including liquid component, solid component, and surface roughness. A higher contact angle means lower wetting ability, while a lower contact angle means that the liquid can spread easier on solid surfaces. The simulation results regarding the effect of contact angle are shown in Table 6 and Figure 6.  
It can be seen that the wetting efficiency decreased significantly with the rise of contact angle because a higher contact angle resulted in accumulation rather than the spread of the liquid on particle surfaces. The same conclusion was made in other investigations on sphere particles. However, there was a noticeable phenomenon that 45\({}^{\circ}\) got the highest liquid holdup. Figure 6 shows that liquid in the 20\({}^{\circ}\) simulation tended to stay close to the particle surface. Most of the voids were free from liquids and some inner holes were not full of liquid. In the 45\({}^{\circ}\) simulation most of the space between particles was filled with liquid, while particles in the 70\({}^{\circ}\) were less surrounded by liquid for the weaker wetting ability. It can be seen that some liquid in the 70\({}^{\circ}\) simulation tended to gather as a liquid drop (the circled position in Figure 6). This discovery of liquid holdup variation might be explained by  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Contact Angle (\({}^{\circ}\))** & **Liquid Holdup** & **Wetting Efficiency** \\ \hline
20 & 0.2503 & 0.6919 \\
45 & 0.2633 & 0.6566 \\
70 & 0.2488 & 0.5691 \\ \hline \hline \end{tabular}
\end{table}
Table 6: Liquid holdup and wetting efficiency of three contact angles.  
Figure 5: Liquid distributions with three surface tension coefficients (\(v_{\text{G}}=0.245\) m/s, \(v_{L}=0.008\) m/s).  
the fact that liquid with a low contact angle tends to flow on particle surface as a thin film, making it harder to fill the voids and inner holes inside the packing. In this case, the gas gains more flow channels and it becomes easier for the liquid to leave the random packing, while liquid with a too high contact angle is less hydrophilic, which tends to gather into a liquid drop on surface and slips down. So it can be concluded that a moderate contact angle can result in high liquid holdup due to its ability of silting channels and cohere with the particle surface.