esa-sceva/satcom-chunk-collection huggingface dataset:
## 2 Model Description  
We consider a multi-server, two-way communication retrial queue with synchronous working vacations and negative arrivals. The detailed description of the proposed retrial queue is as follows.  
* **Arrival and retrial process**: The inbound calls obey a Poisson arrival process with rate \(\lambda\). The incoming call finding that the servers fully occupied or down will either leave the system or be routed to a retrial queue and follows a constant retrial policy that attempts to seek service after an exponential distribution with rate \(\
u\). Otherwise, the call begins its service immediately. We assume that the probability of a call joining the retrial queue when the servers are in regular busy mode is \(b_{b}\), the probability of a call joining the retrial queue when the servers are on vacation is \(b_{v}\), and the probability of a call joining the retrial queue when the servers are under repair is \(b_{r}\).
* **Regular service process**: The number of main servers is \(c\). The services provided by the main servers are defined as regular services. Whenever a new incoming call or a retrial call arrives and there is at least one idle main server, the server immediately begins normal service for the call. The idle main server, after an exponentially distributed time with mean \(1/\alpha\), can make an outgoing call. The time taken to serve incoming (outgoing) calls is exponentially distributed, with rate \(\mu_{1}\) (\(\mu_{2}\)).
* **Removal rule and working breakdown process**: When the main servers are in operation, a disaster happens at any time. The disaster obeys an exponential distribution with rate \(\delta\). When a disaster happens, all the main servers fail and all in-service calls are removed immediately from the system, but there is no impact to the orbit. The repair process begins immediately to restore its functionality after a failure event occurs. After the repair is completed, the main servers are in operation if there is one more customer in the system, including any in service. Otherwise, the main servers go on vacation at the same time. The repair time obeys an exponential distribution with rate \(\gamma\). The standby servers give service at a lower rate of service for inbound calls while the main server is repaired. The working breakdown service time obeys an exponential distribution with rate \(\mu_{w}\). If there are still customers in the system when the repair is completed, the standby servers will be taken out of service and the main servers will be restarted and operate at regular service rates.
* **Synchronous working vacation process**: When the system is found to be empty after a service or repair is completed, all the servers will take a working vacation simultaneously. The vacation time is exponentially distributed with parameter \(\eta\). The servers provide a lower service rate to incoming calls arriving during this period, following an exponentially distributed rate \(\mu_{w}\).
* All the stochastic processes mentioned above are assumed to be mutually independent.
## 3 Retrieval
### Setup
#### 3.1.3 Forward Model \(\vec{F}\)  
The forward model is a vector function of dimension \(m\times 1\) that simulates the measurement vector, i.e., OCO-2 measurements. Its inputs are the state and parameter vector defining the geophysical and instrumental state. Primarily, the forward model consists of the RT model described in Section 2. The RT computations require a discretization of the atmosphere which we split into 20 homogeneous layers, each containing the same number of dry-air particles (i.e., molecules).  
Additionally to the RT calculations, the forward model simulates the instrument by convolving the RT simulations performed on a fixed high resolution wavelength grid with the instrumental line shape function (ILS) obtained from the same OCO-2 L1b example file mentioned above. Furthermore, the forward model has the ability to simulate zero level offsets (i.e., additive radiance offsets), shift and squeeze the wavelength axes of the fit windows according to Equation (31), and squeeze the ILS according to Equation (33).  
\[\lambda^{\prime} = \lambda+\lambda_{\text{sh}}+\lambda_{n}\,\lambda_{\text{sq}} \tag{31}\] \[\lambda_{n} = 2-4\,\frac{\lambda_{1}-\lambda}{\lambda_{1}-\lambda_{0}} \tag{32}\]  
Here \(\lambda^{\prime}\) is the modified wavelength, \(\lambda\) the nominal wavelength, \(\lambda_{\text{sh}}\) the wavelength shift parameter, \(\lambda_{n}\) the normalized nominal wavelength, \(\lambda_{\text{sq}}\) the wavelength squeeze parameter, and \(\lambda_{0,1}\) the minimum or maximum of \(\lambda\), respectively. The normalization of \(\lambda\) is done in a way that the average absolute value of \(\lambda_{n}\) is approximately one.  
\[\lambda^{\prime}_{\text{ILS}} = \lambda_{\text{ILS}}\,\text{ILS}_{\text{sq}} \tag{33}\]  
Here \(\lambda^{\prime}_{\text{ILS}}\) is the modified ILS wavelength computed from the nominal ILS \(\lambda_{\text{ILS}}\) wavelength and the squeeze parameter ILS\({}_{\text{sq}}\).
# Hake Fish Preservation Using Plant-Based Impregnated Polylactic Acid Food Films as Active Packaging
###### Abstract  
Global fish consumption has steadily increased; however, fishery products are difficult to preserve. Active packaging has emerged as an alternative to improve its conservation. In this work, fresh hake fillets were packaged in commercial polylactic acid films impregnated with olive leaf extract using supercritical CO\({}_{2}\). The impregnation was performed at 35 \({}^{\circ}\)C and 400 bar for 1 h. The ABTS assay was used to determine the antioxidant activity, and migration tests were performed using food simulants A and D2 for 10 days at 5 \({}^{\circ}\)C. The fresh fillets were packaged in impregnated and control films and stored for 12 days at 4 \({}^{\circ}\)C. The microbiological, physical (dirp loss, \(\mathrm{a}_{\mathrm{w}}\), pH, and color) and chemical parameters (total volatile base and trimethylamine) were analyzed. The impregnated films presented a 706 \(\mathrm{\SIUnitSymbolMicro g}\) extract \(\mathrm{mg}^{-1}\) polymer, showing a 2-fold extract release using food simulant D2 than simulant A. After hake storage using impregnated films, reduced microbial count, and drip loss, maintaining the pH stability was obtained. The color turned yellowish and no detectable olfactory presence of the extract was noted. The chemical parameters were similar in both types of films. The proposed biodegradable packaging with olive by-products preserves moisture and controls microbial growth, representing an eco-friendly alternative.  
hake fish; polylactic acid; olive leaf extract; supercritical fluids Article
# Brain-Inspired Data Transmission in Dense Wireless Network
## 4 Network Reliability Assessment through the Percolation Theory  
The performance and efficiency of communication networks are expressed in terms of various metrics. One of them, seriously considered in recent years in terms of evaluation of future wireless networks, is reliability. In the context of the fourth generation of the cellular networks, the level of so-called \"four nines\" was considered as the target of guaranteed network reliability. Analogously, \"five nines\" have been treated as the goal for the fifth generation. These values correspond in general to the probability of lack of packet delivery at the levels of 0.01% and 0.001%, respectively. When looking at the pure definition of the term, reliability is the probability specifying that the wireless network operates properly without any device or link failure [39]. However, these terms should not be confused with availability, which describes the proportion of time when the system is in a functioning condition. Various methods can be used for reliability assessment, e.g., Markov Chains, Fault Trees, or RBD [39]. However, these approaches do not reflect well or easily the stochastic nature of such dense wireless networks, whose performance strongly depends on the current node distribution and node load.
## 3 Results and Discussions
### Active Flow Control
#### 3.2.1 Effect of the Different Active Flow Control Types
There is a considerable drag coefficient reduction when using an unsteady jet; however, the momentum introduced into the wake region is not as much as when using a steady blowing jet, leading to a restrained modification of the wake structure. Thus, an aerodynamic drag reduction is limited. In contrast, a negligible decrease in drag coefficient in the synthetic jet case demonstrated that the output momentum of this device is insufficient to modify the near-wake section behind the model. Experimental [29] and LES simulation results [19] on a simplified bus model also showed that no aerodynamic drag reduction was achieved with a synthetic jet actuator at low control frequencies. The control effect is also visualized with small-scale vortices by Q-criterion with an iso surface of Q = 300,000 s\({}^{-2}\) (Figure 16). Clearly, the control jets interact with the shear layer and significantly affect on the wake section. The vortices in the shear layer move further downstream and merge to form larger vortices. However, when control jets are applied, a delay in forming small-scale vortices occurs. Figure 16a shows that the steady blowing jets pushed the vortices on the shear layer away from the rear edges of the model, and the number of vortices is also significantly reduced. These vortices move into the wake region and enhance the mixing, thereby reducing the backward flow as observed in Figure 15. In addition, Figure 16a also reveals that a reduction in wake section size is obviously observed with the steady blowing jet. No evidence of the above phenomena is clearly shown when using the synthetic jet (Figure 16b) and the unsteady jet (Figure 16c); however, a displacement of the small-scale vortices on the shear layer away from the rear surface of the model remains to be determined. Figure 16: Cont.
# Improved ECG Watermarking Technique Using Curvelet Transform
## 7 Discussion  
In this presented technique, the authors embedded patient information as a watermark into ECG signals. As the coarse-level maintains most of the energy of image, this level was chosen to make the watermark more robust. To obtain the coarse-level coefficients, clustering approaches were used. To verify the strength of the cluster, the watermark was embedded into the ECG signal. Even when the watermark was embedded as a text image, some false-positive occurred, that not only degraded the quality of the extracted watermark, but also effected the robustness of the image. Hence, the text must be the embedded as a single unit. The method applies to some biometric techniques like fingerprint, MRI, CT-scan, etc. However, to obtain optimum results, the use of morphologic operators may be different. Moreover, QRS waves are not used in all types of biometrics. Additionally, the work was limited to images only, as it was applicable only for embedding the text watermark. So algorithm  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Performance Metric** & **Watermark Size** & **PSNR** & **KL** & **MSE** & **BER** & **PRD** \\ \hline
**HH Scale DWT-SVD** [12] & \(67\times 67\) (4489 bits) & 50.44 & 0.15 & 0 & 0 & 0.59 \\ \hline
**Adaptive Threshold** & \multirow{2}{*}{251 bytes (2008 bits)} & \multirow{2}{*}{60.68} & \multirow{2}{*}{0.0027} & \multirow{2}{*}{0.05} & \multirow{2}{*}{0} & \multirow{2}{*}{0.0018} \\
**Method**[15] & & & & & & \\ \hline
**Quantization** & \multirow{2}{*}{251 bytes (2008 bits)} & \multirow{2}{*}{73.75} & \multirow{2}{*}{0.00023} & \multirow{2}{*}{0.002} & \multirow{2}{*}{0.04} & \multirow{2}{*}{0.04} \\
**Approach**[16] & & & & & & \\ \hline
**Proposed Technique** & \multirow{2}{*}{67\times 67 (4489 bits)} & \multirow{2}{*}{78.0702} & \multirow{2}{*}{0.0000455} & \multirow{2}{*}{\(3.38\times 10^{-4}\)} & \multirow{2}{*}{0} & \multirow{2}{*}{0.105} \\ \hline \hline \end{tabular}
\end{table}
Table 5: Comparison of proposed technique with existing ECG techniques.  
with steganography may need further dataset. Today, with everything digital for security reasons, said methodology may be used for better encryption. To enhance the scope of the technique utilization of deep learning, machine learning may be incorporated as a further improvement for automation. In a nutshell, as a medical application, the work can be extended to medical video-watermarking, voice-watermarking and online-content security, etc.
# A Vehicle Conflict Risk Identification Method Based on an Improved Intelligent Driver Model
## 5 Conclusions  
Accurate assessment and prediction of traffic conflict risks are critical priorities in traffic safety research. To address the deviations between simulation results and real-world traffic flow characteristics caused by the inherent randomness of microscopic traffic simulation tools, this study proposes a vehicle conflict risk identification method based on an improved intelligent driver model (IDM). A realistic traffic scenario was constructed using VISSIM 4.3 simulation software, with speed distribution calibrated to ensure high consistency between the simulated and real-world traffic environments. To account for the complexity of real-world driver decision making, the IDM was enhanced by integrating driver-state parameters and braking variables. Vehicle speed and headway data generated by VISSIM were input into the model, enabling parameter calibration through iterative optimization. Using the improved IDM, the inverse time to collision (ITTC) was calculated as the primary indicator for collision risk assessment. Three collision risk thresholds were established: potential conflict risk (ITTC \(<\) 0.25 1/s, TTC \(>\) 4 s), general conflict risk (0.25 1/s \(\leq\) ITTC \(\leq\) 0.48 1/s, 2.1 s \(\leq\) TTC \(\leq\) 4 s), and serious conflict risk (ITTC \(>\) 0.48 1/s, TTC \(<\) 2.1 s). The proposed conflict risk identification method was validated using a large sample dataset. The results demonstrate high accuracy: identification rates exceeded 95% for potential and general conflicts and reached 92.71% for serious conflicts. These findings confirm the method's effectiveness and practicality. The study provides a theoretical foundation for real-time risk prediction and proactive collision avoidance strategy design in intelligent driving systems.  
While the improved IDM framework proposed in this study advances traffic conflict risk identification, limitations persist in addressing driver behavior variability and the impacts of complex road environments and adverse weather conditions. As discussed above, our future work will focus on enhanced behavioral and environmental realism as well as integration with intelligent systems.  
Conceptualization, S.Q. and A.Z.; methodology, S.Q.; software, A.Z.; validation, A.Z.; formal analysis, S.Q.; investigation, A.Z.; resources, S.Q.; data curation, S.Q. and A.Z.; writing--original draft preparation, S.Q. and A.Z.; writing--review and editing, S.Q. and A.Z.; visualization, A.Z.; supervision, S.Q. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research was supported by the Fujian Province Education System Philosophy and Social Science Research Project (JAS24028), Postdoctoral Fellowship Program of CPSF (GZC20240179).  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** The data presented in this study are available on request from the corresponding author due to privacy reasons.  
**Conflicts of Interest:** The authors declare no conflicts of interest.
## 5 Classification and Regression of the Runway Overrun Risk
### Regression Analysis of the Runway Overrun Risk
#### 5.1.2 Regression Model and Evaluation Metrics  
Regression analysis is performed with Equation (6) as the prediction target, using the nine features from Table 2. The machine learning models applied include LR, neural networks (NNs), decision trees (DTs), random forests (RFs), and support vector regression (SVR).  
The evaluation metrics include the mean absolute error (MAE), root mean square error (RMSE), and mean absolute percentage error (MAPE), which are calculated as follows:  
\[\text{MAE}=\frac{1}{n}\sum_{i=1}^{m}\mid y_{i}-\hat{y_{i}}\mid \tag{9}\]  
\[\text{RMSE}=\sqrt{\frac{1}{n}\sum_{i=1}^{m}(y_{i}-\hat{y_{i}})^{2}} \tag{10}\]  
\[\text{MAPE}=\frac{1}{n}\sum_{i=1}^{m}\mid\frac{y_{i}-\hat{y_{i}}}{y_{i}}\mid \tag{11}\]  
where \(y_{i}\) and \(\hat{y_{i}}\) represent the ground truth and predicted values of the model, respectively.
# Implementation of a Fast Link Rate Adaptation Algorithm for WLAN Systems
## 4 Operating Speed of the Link Adaptation  
### Execution Time Breakdown and Analysis  
Figure 14 shows the analysis of the internal functions of the firmware after repeating APBLA before optimization. The experiments are made with the Xilinx Zynq 7020 programmable SoC chip that includes an embedded ARM Cortex A9 core running at 667 MHz. The timer (individual) column is obtained by measuring the execution time of each internal function in the APBLA firmware by using platform-provided library functions. The timer (overall) column is obtained by algebraically estimating the execution time according to the number of function calls of the internal functions after measuring the execution time of the overall APBLA. The measured values for the two means, timer (individual) and timer (overall), are generally similar to each other.  
It is conjectured that although the experimental environment (e.g., performance of the microprocessor unit, clock frequency, etc.,) of the SoC platform may be different than the actual operating environment of link adaptation, the ratio of each function affecting the overall execution time in the platform case will be similar to that in the actual link  
Figure 14: Execution time per packet for each function.  
Figure 13: Linear interpolation.  
adaptation case. The snr2 mi_interp function occupies about half of the overall execution time and the interp function with the snr2 mi function is the next culprit concerning the latency. Thus, these three functions are the targets for optimization as far as the link adaptation firmware speed enhancement is concerned.
## 2 Intent-Estimation- and Motion-Model-Based Collision Avoidance Method  
### Overview  
For autonomous vehicles, the trajectories of the detected vehicles are not deterministic, as they are affected by the environment, the destination of the driver and driving habits, which increase the difficulty of collision avoidance. However, certain considerations about the dynamic features of the moving vehicle, traffic rules and the road structure around the vehicle can provide some information to facilitate predictions. For instance, it is known that the maximum acceleration of a vehicle is limited, and the trajectory curvature must be smaller than a certain value to ensure stability. The varying driving habits of different drivers may lead to different trajectories; however, some common rules should be followed to ensure comfort and safety, such as following the center line of the lane, which is defined as normal moving in this paper.  
The structure of the proposed IEMMB method is shown in Figure 1.  
Online sensor information and a priori environmental information are combined to increase the accuracy and robustness of environmental perception, which is crucial to collision avoidance. Then, the road structure and moving vehicles are extracted; the driving intent of the detected moving vehicles can be estimated using this information. In the next step, the long-term trajectory considering driving intent and the short-term trajectory considering the current moving state, as well as motion model are combined to predict the real trajectory. With the prediction, potential collisions can be detected, and appropriate evasive maneuvers will be generated to avoid collisions in the space or time dimension.
# Design and Implementation of Composed Position/Force Controllers for Object Manipulation
## 5 Grasping Stage
### Position-Force Hybrid PID Controller  
As mentioned previously, PID controllers are widely used in the industry for implementing control systems. Due to its operational ease and low cost, the first implemented controller is based on a hybrid PID scheme; i.e., it consists of two PID controllers: a position PID and a force PID operating in a switching mode as shown in Figure 5. It is important to remark that either of the gripper fingers uses this control scheme.  
The first controller is responsible for placing and keeping the object at desired position. This controller works as follows: it switches on when the object is not centered, and it switches off when the object is centered. On the other hand, the force controller ensures that the fingers will apply enough force to manipulate an object firmly. This controller works when the position controller is switched off; i.e., the position error is zero.
# A Novel Coding Based Dimming Scheme with Constant Transmission Efficiency in VLC Systems
###### Abstract  
Visible light communication (VLC) has attracted tremendous attention due to two functions: communication and illumination. Both reliable data transmission and lighting quality need to be considered when the transmitted signal is designed. To achieve the desired levels of illumination, dimming control is an essential technology applied in VLC systems. In this paper, we propose a block coding-based dimming scheme to construct the codeword set, where dimming control can be achieved by changing the ratio of two levels (ON and OFF) based on on-off keying (OOK) modulation. Simulation results show that the proposed scheme can maintain good error performance with constant transmission efficiency under various dimming levels.  
VLC; block code; dimming control; encoding/decoding algorithm Article  
A Novel Coding Based Dimming Scheme with Constant Transmission Efficiency in VLC Systems  
1  
Footnote 1: email: {[EMAIL_ADDRESS], [EMAIL_ADDRESS], [EMAIL_ADDRESS], [EMAIL_ADDRESS], zhang@gmail.  
the transmission efficiency cannot be fixed under different dimming levels, which may cause a severe effect on data transmission.  
In order to solve the problem of the transmission efficiency not being constant under different dimming levels, we propose a block coding-based dimming scheme to achieve data transmission and dimming control simultaneously. Via bitwise AND operation of the block code and dimming code, new codewords are generated to satisfy the dimming requirement. Simulation results show that the proposed scheme can maintain constant transmission efficiency under different dimming levels, and it proves an attractive alternative to the dimming scheme.  
The remainder of this paper is organized as follows: In Section 2, the system model of the proposed block coding scheme is given. In Section 3, the implementation of the proposed coding scheme is demonstrated and the construction of the encoding/decoding algorithm is summarized accordingly. In Section 4, simulations are carried out to evaluate the error performance of the proposed scheme. Finally, we conclude our findings in Section 5.