esa-sceva/satcom-chunk-collection huggingface dataset:
## 4 Convergence
### Stability  
Based on the Lax equivalence theorem, the parameters \(\alpha,\beta_{1},\beta_{2},\beta_{3},\gamma_{1}\) and \(\gamma_{2}\) are restricted by the stability conditions. Therefore, the limiting cases of \(\Omega_{0}\to 0\) and \(\Omega_{0}\to\infty\), for the stability conditions, are used to find out the restrictions of these parameters. Hence, the characteristic equation of CVM, as demonstrated in Equation (9), in correspondence to the limiting cases of \(\Omega_{0}\to 0\) and \(\Omega_{0}\to\infty\), are found to be  
\[\begin{array}{ll}\big{(}\lambda-\frac{\alpha}{1+\alpha}\big{)}(\lambda-1)^{ 2}\ =\ 0&\text{as}\ \Omega_{0}\to 0\\ \lambda\Big{[}\lambda^{2}-\Big{(}2-\frac{1+\alpha}{\beta_{3}}\Big{)}\lambda+ \Big{(}1-\frac{\alpha}{\beta_{3}}\Big{)}\Big{]}\ =\ 0&\text{as}\ \Omega_{0}\to\infty,\end{array} \tag{14}\]  
and its correspondent roots are:  
\[\begin{array}{ll}\lambda_{1,2}\ =\ 1,\ \lambda_{3}\ =\ \frac{\alpha}{1+ \alpha}&\text{as}\ \Omega_{0}\to 0\\ \lambda_{1,2}\ =\ 1-\frac{1+\alpha}{2\beta_{3}}\pm\sqrt{\Big{(}\frac{1+\alpha}{2 \beta_{3}}\Big{)}^{2}-\frac{1}{\beta_{3}}},\ \lambda_{3}\ =\ 0&\text{as}\ \Omega_{0}\to\infty.\end{array} \tag{15}\]  
In the limit \(\Omega_{0}\to 0\), the spurious root \(\lambda_{3}\) only depends upon \(\alpha\), and \(\alpha\geq 0\) is needed so that \(\lambda_{3}\leq 1\). On the other hand, in the limiting case of \(\Omega_{0}\to\infty\), the principal roots are functions of \(\alpha\) and \(\beta_{3}\), and it seems that the simplest way to determine the relationship between \(\alpha\) and \(\beta_{3}\) leads to:  
\[\beta_{3}\ =\ \frac{1}{2}\bigg{[}\alpha+\frac{1}{2}\bigg{]}, \tag{16}\]Therefore, the second line of Equation (15) determines that the two principal roots are found to be \(\lambda_{1}\ =\ \Big{(}\alpha-\frac{1}{2}\Big{)}\backslash\Big{(}\alpha+\frac{1}{2} \Big{)}\) and \(\lambda_{2}\ =\ -1\), in addition to \(\lambda_{3}\ =\ 0\). Figure 1 represents the variations of \(\lambda_{1}\), \(\lambda_{2}\) and \(\lambda_{3}\) with \(\alpha\). This figure tells us that CVM is stable in the limit \(\Omega_{0}\rightarrow\infty\), and reveals that the range of \(0\leq\alpha\leq\frac{1}{2}\) is of practical interest for a linear elastic system. There is an excellent idea to simplify the stability conditions in the limit \(\Omega_{0}\rightarrow\infty\) by assuming that the roots are in terms of \(\rho_{\infty}\) that is actually a special case of the spectral radius, which is generally defined as \(\rho\ =\ \max\big{(}\ \ |\lambda_{1}|,\ \ |\lambda_{2}|,\ \ |\lambda_{3}|\ \ \big{)}\) for the general value of \(\Omega_{0}\). Hence, the coefficients are found to be:  
\[\begin{array}{l}\alpha\ =\ \frac{1-\rho}{2(1+\rho_{\infty})}\ =\ -\frac{1}{2}+\frac{1}{1+\rho},\ \beta_{1}\ =\ 1,\ \beta_{2}\ =\ \frac{1}{2}\Big{(}1-\frac{1}{1+\rho}\Big{)}\ =\ \frac{1}{2}-\frac{1}{1+\rho},\\ \beta_{3}\ =\ \frac{1}{1+\rho},\ \gamma_{1}\ =\ 1-\frac{1}{1+\rho},\ \gamma_{2}\ =\ \frac{1}{1+\rho}.\end{array} \tag{17}\]  
From the stability conditions, the interval range of \(\rho\) is found to be \(0\leq\rho\leq 1\).
# A Novel Physics-Guided Neural Network for Predicting Fatigue Life of Materials
## 2 Materials and Methods
### Empirical Model  
The traditional life prediction model is an explicit model, which has the advantage of a simple structure. For example, in 1910, [PERSON] [6] proposed the following power-law expression describing load and fatigue life:  
\[\sigma=\sigma_{f}^{\prime}\Big{(}N_{f}\Big{)}^{b} \tag{1}\]  
where \(\sigma\) represents the stress level under the loading cycle of the material, \(N_{f}\) is the fatigue life, and \(\sigma_{f}^{\prime}\), \(b\) represents the fatigue constant under a given load.  
Formula (1) shows that under a certain loading environment (temperature, corrosion, stress concentration factor, etc.), the fatigue life of the material is a certain power function relationship with its actual load. The fatigue performance constant (\(\sigma_{f}^{\prime}\), \(b\)) characterizes its specific loading environment, that is, all loading environments can be determined by two fatigue performance parameters, \(\sigma_{f}^{\prime}\) and \(b\). Therefore, it is feasible to establish a model with loading environment parameters as input and fatigue parameters (\(\sigma_{f}^{\prime}\), \(b\)) as output to predict the fatigue life of materials under different loading conditions.  
In 1914, [PERSON] [24] proposed the following expression based on the Basquin formula:  
\[(\sigma-\sigma_{f})=\sigma_{f}^{\prime}\Big{(}N_{f}\Big{)}^{b} \tag{2}\]  
In this expression, \(\sigma_{f}\) characterizes the fatigue limit of the material.  
Formula (2) introduces the fatigue limit of the material on the basis of the Basquin equation. However, the new parameter has limited improvement in the accuracy of fatigue life prediction. The smaller the number of parameters to be determined, the more conducive to the convergence of the model. Based on the above reasons, this study uses Formula (1) to establish a fatigue life prediction model.  
In order to calculate the fatigue life conveniently, Formula (1) is rewritten as follows:  
\[N_{f}=(\frac{\sigma}{\sigma_{f}^{\prime}})^{\frac{1}{b}} \tag{3}\]  
The range of common fatigue cycle life values can be distributed between \(1\times 10^{2}\) and \(1\times 10^{8}\). Parameters of such an order of magnitude cannot be calculated in a neural network that relies on gradient update. The commonly used method is to change the fatigue life and load into a logarithmic form:  
\[\log N_{f}=\left(\frac{1}{b}\right)\Big{(}\log\sigma_{max}-\log\sigma_{f}^{ \prime}\Big{)} \tag{4}\]  
The fatigue performance parameters \(\sigma_{f}^{\prime}\) and \(b\) can be obtained from the fatigue test results, and the fatigue life of any load value under the corresponding loading environment can be estimated.
## 5 Conclusions  
(1) Yearly average NPP figures within most areas of northwestern Liaoning were within the span of 300 to 400 gC\(\cdot\)m\({}^{-2}\cdot\)a\({}^{-1}\), which was a medium level. The area with the highest values was the southwestern part of the region, where the annual average NPP value exceeded 400 gC\(\cdot\)m\({}^{-2}\cdot\)a\({}^{-1}\), and the area with the lowest values was the northern section of Chaoyang City and the western area of Fuxin City, where the annual mean NPP value was less than 300 gC\(\cdot\)m\({}^{-2}\cdot\)a\({}^{-1}\). The interannual changes in the mean NPP values in different regions had a variable upward pattern, and the slope of the change in the NPP values displayed a downward trend from the northwest toward the southeast. Areasshowing an upward trend were predominantly located in the northwestern and central parts of the region.  
(2) The NPP in northwestern Liaoning was significantly influenced by climatic variations, with 74% of the region impacted by both precipitation and temperature. In most areas, NPP was mainly driven by precipitation, particularly in Chaoyang City, Fuxin City, Kangping County, the north-central region of Huludao City, and the northern part of Jinzhou City. In the rest of the area, NPP was mostly driven by non-climate factors. However, the specific impact of non-climate-driven factors on NPP needs further exploration.  
(3) NPP was also driven by both soil and vegetation and showed a fluctuating upward trend in different soil categories within the research area. The NPP of the nine soil categories ranked in descending order were as follows: alifsiol soil, ferroaluminous soil, primordial soil, semi hydromorphic soil, semi-alfisiol soil, anthropogenic soil, hydromorphic soil, saline soil, and calcareous layer soil. However, the extent of fluctuation in NPP also differed among soil types.  
(4) Land use changes can cause changes in NPP. Within the research area, the yearly average NPP value in descending order was as follows: forested areas, grassy lands, cultivated land, built-up land, unused land, and water. The specific impact was evident in the increase in the total NPP under forest and built-up land, while the increase in the changed area of cultivated land and grassland caused a significant decrease in the total NPP.  
Conceptualization, W.Z.; methodology, T.W.; software, T.W.; validation, W.Z.; formal analysis, W.Z.; investigation, T.W.; resources, T.W.; data curation, W.Z.; writing--original draft preparation, T.W.; writing--review and editing, W.Z.; visualization, T.W.; supervision, W.Z.; project administration, W.Z.; funding acquisition, W.Z. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the National Natural Science Foundation of China, grant number 40571016 and the Distinguished Professor Program of Liaoning Province, grant number 60618006.  
Not applicable.  
The raw data supporting the conclusions of this article will be made available by authors on request.  
The authors declare no conflicts of interest.
# A Watermark-Based In-Situ Access Control Model for Image Big Data
## 3 Problem Formulation
### Design Goals  
We list design goals as follows: Design a novel access control flow that migrates the control unit from servers to clients. Design a watermark-based access control model that provides fine-grained access control for various areas or layers in a single image. Defend against attacks imposed by traditional access control models and propose a tailored design for big data sharing and redistribution of images with large sizes.  
Remark 1: _Images can be downloaded only from servers who embed access policies into images via watermarks._  
_Images can only be viewed via particular client tools, such as an image browser that can extract watermarks, parse watermark semantics into policies, and enforce access control policies before viewing. The context of watermarks can be recognized by corresponding clients._  
_Accessors may register their roles on servers at first, and their roles can be affirmed by client tools before viewing images._  
_The client tool can transparently decrypt images by asking for the correct keys. After accessors view their corresponding partial areas, those areas are encrypted again by client tools transparently._  
_If a hard copy of images is obtained by screen capture or photo shooting, watermarks in images can facilitate the trace back to the accessor who was the last authorized viewer._
## 3 Methodology: A CRISP-DM Approach to a Real Case
### Evaluation
Robustness was assessed by testing different contamination rates to balance sensitivity and specificity. A subset of flagged anomalies was manually audited by domain experts to confirm their novelty or relevance, ensuring the method's practical utility. The operational impact was evaluated by integrating the models into the agency's complaint management workflow and measuring efficiency gains. Key performance indicators included reductions in repeated complaint categories, time saved in classification and routing, and decreases in user-reported errors post-intervention. These metrics were tracked using helpdesk logs over a six-month period, with pre- and post-deployment comparisons to quantify improvements. User interface adjustments, informed by cluster and anomaly insights, were tested to assess their effect on complaint clarity and resolution rates. Feedback from support staff was collected to evaluate the system's usability and alignment with operational needs.
## 3 Controller Design
### Design of \(H_{\infty}\)/Leitmann Control for the Uncertain System
The new control scheme of this turbofan is depicted in Figure 2. In this control scheme, the reference model receives the commands and outputs the reference states and control forces, which combine with the engine states and control forces to form signals of the tracking system, such as \(N_{L}-N_{Lss}\). The \(H_{\infty}\)/Leitmann controller takes the tracking errors as inputs and gives the outputs, which collaborate with the outputs of the reference model, to obtain the final control forces for the engine. It is worth noticing that the reference model has two contributions here. First of all, it provides the reference tracking trajectory for the states of the engine. Secondly, its control forces guarantee the baseline of controls for the engine, which will enhance the stability of the controlled system.
# Enhancing Street-Crossing Safety for Visually Impaired Pedestrians with Haptic and Visual Feedback
## 1 Introduction
To address this gap, we explored feedback effectiveness in two distinct scenarios: signal-controlled intersections where pedestrians follow traffic signals and vehicle crossing scenarios where they navigate based on approaching vehicles. Two assistive systems were designed and evaluated to determine the optimal feedback mode and parameters for each context. Our findings reveal distinct advantages in different scenarios, summarized as follows:  
* In the traffic light crossing scenario, visual feedback significantly improved users' decision-making efficiency and facilitated faster decisions, regardless of their confidence levels. * In the vehicle crossing scenario, haptic feedback significantly enhanced decision efficiency, with dynamic haptic feedback outperforming dynamic visual feedback. * In both scenarios, the high-frequency visual feedback encouraged users to make more cautious decisions, while haptic feedback was widely preferred by users due to its comfortable experience. Based on the findings above, we validated the application value of haptic and visual feedback in assisting visually impaired individuals with crossing decisions, providing critical insights for designing decision-support systems in traffic light-controlled and vehicle crossing scenarios. The study indicates that users can select their preferred feedback modality in traffic light scenarios based on personal preferences, while haptic feedback demonstrates significant advantages in vehicle crossing scenarios. These findings offer effective design strategies for improving the safety and convenience of daily mobility for visually impaired individuals. The organization of this paper is as follows: Section 2 reviews related studies, focusing on haptic and visual feedback technologies for assisting visually impaired individuals. Section 3 details Experiment 1, which examined the effectiveness of haptic and visual feedback in a traffic light crossing scenario. Section 4 presents Experiment 2, exploring their utility in a vehicle crossing scenario. Section 5 discusses the results, analyzing the applicability and user preferences for different feedback modalities. Finally, Section 6 concludes the study and suggests future research directions.
## 2 Materials and Methods
### PhenoCam Data  
The PhenoCam dataset provides digital camera images composed of three channels, red (R), green (G), and blue (B), and can be used to derive vegetation statistics and vegetation index in the region of interest (ROI) based on given masks. The provided dataset consists of time series of digital number (DN) and vegetation indices (VIs) that can reveal phenological changes [26], including the RGB chromatic coordinates (i.e., Rcc, Gcc, and Bcc). The Gcc can be defined as:  
\[\mathrm{Gcc}\ =\frac{\mathrm{G}}{\mathrm{R+G+B}} \tag{1}\]  
where RGB represents the DN of the red, green, and blue channels. Gcc has been more widely used in recent studies and PhenoCam networks because it can decrease the effect of environmental illumination, thus enhancing the monitoring of vegetation dynamics [12; 27; 28; 29; 30; 31; 32].  
The Level 3 product of the PhenoCam dataset includes the statistics of DN and VIs of each image with a time resample of 30 min, taken from cameras at a height of \(-\)300 m, while the Level 4 product includes 1 and 3-day averages for contents of Level 3. The PhenoCam dataset applies spline interpolation to remove Gcc outliers caused by environmental variables when processing Level 4 time series into Level 5 products when extracting the phenological metrics. Dynamic thresholds of the 10 th, 25 th, and 50 th quantiles were applied to determine the SOS and EOS from Level 5 products on the rising or falling amplitudes, respectively [26].  
The PhenoCam datasets have been validated to be consistent with ground observations, near-surface radiometry, and satellite remote sensing by [PERSON] et al. [33] In this study, the transition date in Level 5 product with a threshold of the 50 th quantile of the amplitude was used for subsequent statistical analysis as a representation of in-situ measurements.
# Receiver-Initiated Handshaking MAC Based on Traffic Estimation for Underwater Sensor Networks +
## 9 Conclusions  
In this paper, we designed a new receiver-initiated system based on traffic estimation, TERI-MAC to achieve efficient communications for UWSNs. In TERI-MAC, receivers replace the role of senders in conventional protocols to initiate the handshaking process. The parallel reservation, shared control packets, and enabled link layer data aggregation in TERI-MAC significantly improve the energy efficiency of UWSNs compared to the long preamble in acoustic modems.  
Figure 14: The hop-by-hop communication delay with respect to the network traffic load.  
Figure 13: The overhead of the control packet with respect to the network traffic load.  
The unique challenges faced in the receiver-initiated MAC approaches, that is, to decide when to poll and how much data to poll, were solved by adopting traffic estimation in our paper. By employing the adaptive data polling mechanism, the receiver in TERI-MAC can initiate handshakes timely to reduce the packet queuing delay while constraining the energy consumption on transmitting control packets. The simulation results verified that our traffic estimation adapts well to dynamic traffic loads in the network, and the adaptive data polling mechanism in TERI-MAC results in stable energy efficiency with varying traffic patterns.  
In the meantime, we carried out extensive simulations and evaluated the energy efficiency, the channel utilization, and the hop-by-hop delay performance of TERI-MAC. The results demonstrate that by adjusting the frequency of data polling, the desired energy efficiency can be achieved. A trade-off between channel utilization and delay performance is also expected in TERI-MAC. Moreover, the comparative experiments proved that the performance of TERI-MAC with traffic estimation outperforms RIPT, a representative receiver-initiated-based underwater MAC protocol. Therefore, we believe that TERI-MAC is a promising MAC solution for delay-tolerant underwater applications.  
All authors contributed to the research of this paper. [PERSON] and [PERSON] composed the original draft, designed the method and carried out the experiments. [PERSON], [PERSON] and [PERSON] made suggestions on the protocol design and edited the whole manuscript. [PERSON], [PERSON] ([PERSON]) and [PERSON] ([PERSON]) made some suggestions on the paper editing and refined the overall manuscript. The article was initially written by [PERSON] and [PERSON] and improved and polished by all of the authors.  
This research was supported by Project of International Cooperation and Exchanges of Shaanxi Province (2016 KW-035); Fundamental Research Funds for the Central Universities in Chang'An University (310832171007); National Natural Science Foundation of China (61701044, 61801372); Natural Science Foundation of Shaanxi Province (2016)Q6067).  
The authors would like to thank [PERSON] and [PERSON] for reviewing the manuscript.  
The authors declare no conflict of interest.
# Performance of Time Reversal Based Underwater Target Detection in Shallow Water
## 4 Simulation
### Simulation Condition  
In order to verify the performance of the proposed scheme by simulation, the target and clutter channels were modeled and Gaussian signals were added to the existing channel every time to simulate the time-varying characteristics of the shallow water acoustic channel. As the initial transmission signal, an LFM (linear frequency modulated) waveform having a bandwidth of 6-20 kHz was employed, and the sampling frequency was set to 44 kHz. An 18 degree beam covering a bottom distance of 100-200 m with a depth of 100 m below the sea surface was employed. The target signal was generated by [PERSON]'s model with a length of 20 m and a radius of 2 m.
## 2 Materials and Methods
### Risk Assessment Framework (ISO 31000 and NFPA 551)  
To quantitatively evaluate the effectiveness of the proposed AI-integrated fire control system, a structured risk assessment was conducted in accordance with the principles outlined in ISO 31000 [52] (Risk Management--Guidelines) and NFPA 551 [53] (Guide for the Evaluation of Fire Risk Assessments). The framework employed a semi-quantitative methodology to estimate and compare life safety, property damage, business interruption, and operational continuity risks between the proposed system and a conventional sprinkler-based setup.  
The assessment began with hazard identification using standardized building fire scenarios, including ignition sources (electrical, combustible material, thermal faults), growth conditions (fast, medium, slow), and occupancy types (residential, data center, underground transport). Each scenario was evaluated under two system configurations: (i) a baseline with traditional sprinkler response and (ii) the proposed hybrid detection and smart suppression architecture.  
Risk was quantified using the Risk = Likelihood \(\times\) Consequence model, where:  
* Likelihood was derived from historical fire incident data and simulated detection delay distributions;
* Consequence was estimated through scenario-based analysis considering occupant egress time, smoke spread dynamics, property exposure, and system response duration.  
Severity levels were categorized into four tiers--low, moderate, high, and critical--across three impact domains:  
* Life Safety Impact (e.g., delayed evacuation, toxic smoke exposure);
* Asset Loss Impact (e.g., fire propagation, collateral water damage);
* Business Disruption Impact (e.g., downtime duration, equipment loss).  
The proposed risk assessment framework provides a systematic basis for evaluating the potential performance of the AI-integrated fire control system. By employing standardized scenarios and a semi-quantitative analytical approach, it enables an objective comparison of key risk domains--including life safety, property loss, and business disruption--between the conventional sprinkler system and the proposed hybrid architecture. This methodology is adaptable to diverse fire ignition conditions and occupancy types, offering reliable risk quantification in complex real-world environments.  
Furthermore, the framework accounts for the dynamic interactions and temporal evolution of risk factors, facilitating a comprehensive understanding of the multilayered mitigation effects delivered by the real-time response system. This structured assessment lays the groundwork for subsequent chapters focused on quantitative performance evaluation and result interpretation, and serves as a valuable reference for the design and policy formulation of smart building fire safety management systems.  
Consequently, the risk assessment approach outlined herein is critical to validating the reliability and effectiveness of the proposed system, and, when combined with the forthcoming empirical findings, substantiates the system's superiority over traditional fire suppression solutions.