esa-sceva/satcom-chunk-collection huggingface dataset:
## 2 Related Work  
### AIS Security  
As outlined in the Introduction, most existing AIS security solutions primarily focus on the application of public key cryptography. In [12, 13], the authors proposed maritime public key infrastructure (mPKI) schemes similar to the X.509 standard, where relevant maritime authorities act as certificate authorities (CAs) to issue digital certificates and generate public and private keys for ships and other maritime nodes. To minimize the overhead associated with PKI-based solutions, [PERSON] et al. [3] proposed a maritime certificateless identity-based cryptography (mIBC) scheme, where the public key is generated from the ship's Maritime Mobile Service Identity (MMSI), and the private key is generated by a dedicated key generation agency. The advantage of this approach is that the public key inherently serves as proof of identity, eliminating the need for a trusted third party to issue a digital certificate. This reduces the complexity of issuing, updating, and revoking certificates. Furthermore, [PERSON] et al. [14] implemented an mIBC-based group key mechanism to prevent person-in-the-middle attacks and integrated edge computing technology for real-time AIS data analysis, enabling the detection of malicious modifications to AIS messages. [PERSON] et al. [15] introduced certificateless digital signatures (CLDSs) to simplify public key infrastructure (PKI) and used Genetic Algorithms (GAs) and Particle Swarm Optimization (PSO) to optimize the parameter generation time for Elliptic Curve Cryptography (ECC), further reducing the overhead. To further enhance the security of AIS broadcasts, [PERSON] et al. [16] proposed the Auth-AIS authentication framework, in which ships utilize a pre-assigned master key to generate a hash key chain \(k_{0},k_{1},\ldots,k_{n}\). Each AIS message employs key \(k_{i}\) corresponding to the current time slot to compute a message authentication code (MAC), effectively mitigating replay attacks on AIS broadcasts. These solutions are all enhancements of PKI-based approaches and still rely on the involvement of a third party, such as a key generation authority. As a result, the challenge remains of establishing a unified third party across different organizations.  
Given the limitations of asymmetric encryption schemes, adopting symmetric encryption algorithms may be a feasible alternative, as symmetric encryption offers higher performance and lower energy consumption compared to asymmetric encryption [17]. [PERSON] et al. [18] proposed a hybrid cryptographic system that combines the implicit authentication scheme of Elliptic Curve Qu-Vanstone (ECQV) and the Elliptic Curve Diffie-Hellman (ECDH) key exchange to secure AIS communications. This system incurs less than 20% of the overhead required by traditional X.509 certificates. Additionally, the EAPSG protocol proposed in [19] also utilizes ECDH for maritime communication security and outperforms existing land-based protocols in terms of transmission cost and message count.
# A Review of Innovative Electromagnetic Technologies for a Totally Artificial Heart
## 3 TAH Electromechanical Components  
The results of the different projects demonstrate that proper TAH operation requires a fully coordinated interaction among the various devices devoted to the supply, control, actuation, and management of all operating phases with a very high level of reliability and efficiency. This section aims to describe the components and their main functions and performances, considering a typical TAH provided with a TET supply system [44] (Figure 2).  
In case of percutaneous supply, the external power source supplies the implanted one or the actuation system by cables and connectors (driveline). The components are:  
* The heart unit (A), consisting of the integrated actuator and pumps or membranes installed in suitable chambers, possibly provided with valves;
* An external battery pack (B) to supply the external user interface (D), which collects information about the performance of the pumps and of the TET system and tunes the system parameters. A portable lithium-ion battery-type (Li-ion) can power the TAH from 4 to 8 h;
* An implanted auxiliary battery (C), acting as a backup unit in case of the failure of the TET system, usually consisting of a Li-ion battery with a nominal voltage of 13 to 24 V, and with enough capacity to ensure 60 minutes of nominal operation [32; 44];
* The TET system, composed of the external transmitting coil (F), which in practice is the primary winding of a transcutaneous high-frequency transformer, whose secondary is the implanted receiving coil (G). The electric power collected by G via the inductive coupling enables recharging of the implanted battery (C) and/or supplies the control circuit of the heart unit (F). A bidirectional data exchange is also present, to monitor and adjust the operating condition of the implanted devices;
* The compliance chamber (E), where blood accumulates to avoid overpressures in the ventricles and to facilitate pumping action;
* The microprocessor-based control unit (H), which regulates the operation mode of the heart unit and checks its status. Usually, the closed-loop architecture ensures adequate control robustness, tuning the control strategy according to the parameters provided by the communication cables (from the TET or heart unit sensors).  
In the following section, some details of the most important TAH components are given, with particular attention on the up-to-date electromagnetic devices with enhanced performance controllability applied in recent TAH projects.  
Figure 2: Typical layout of the devices forming a TET supplied TAH; solid lines: power connections; and dotted lines: data transmission cables.
## 6 Discussion and Limitations
Factors such as sensor power consumption and sensed parameters influence the overall network design by influencing routing protocol selection, damage detection algorithm selection, damage localization algorithm selection, and network lifespan. As can be seen in Table 5, the most frequent sensors utilized in the selected studies of this SLR are accelerometers (27 studies), temperature sensors (14 studies), and strain gauges (11 studies). **Discussion on inspection scale:** The inspection scale of the SHM system for bridges can be classified into two main categories: local and global approaches. As can be seen in Table 6, the most frequent system utilized in the selected studies of this SLR is the global system (31 studies), whereas only 5 studies apply local inspection systems. **Discussion on response type:** The damage identification process can be classified, in terms of response type, into dynamic (frequencies, mode shapes, or modal damping) and static (strain or stress) systems. As can be seen in Table 7, the most frequent system utilized in the selected studies of this SLR is the dynamic response system (18 studies). On the other hand, only four studies apply static response systems. Both dynamic and static response analysis have been combined in 15 studies of this SLR. **Limitations of research:** Despite the fact that SLR is purely based on the standard guidelines of [32], there are various small issues that have been highlighted as follows:  
* We have used the related keywords during the search process to obtain a significant number of research articles. The obtained research articles have been scanned in a systematic way according to a predefined selection/rejection criterion. Nevertheless,there is no guarantee of the completeness of this scanning process. Moreover, a considerable number of studies have been excluded on the basis of their title. Now, it is quite possible that the titles of the article do not depict the complete research idea of the article. Based on these facts, it is very hard to claim the exhaustiveness of the research conducted in this article. * In addition to the limitations of the search process and selection/rejection criterion, another probable limitation is the selection of target databases. We have targeted seven well-known databases i.e., IEEE, ELSEIVER, SPRINGER, SAGE, Wiley, MDPI, and Taylor & Francis. These seven databases provide a variety of well-reputed scientific journals and conference proceedings. Nevertheless, there exist several other databases that also provide a lot of scientific articles. Consequently, there is a fair possibility that we have excluded recent research from other databases. However, we firmly believe that the final results of this SLR are not considerably affected because high-quality recent research is available in the selected scientific databases.
# Opportunistic and On-Demand Network Coding-Based Solutions for LPWAN Forwarding
## 6 Implementation and Evaluation
### Evaluation  
#### 6.3.1 Studying LoRa Reliability  
LoRaWAN regulation in South Korea allows choosing between 1% of duty-cycle and LBT approach in order to use the physical medium. This duty-cycle is good for saving the energy, suited for the end-devices that only wake up and transmit when it has a packet. Conversely, the relay is an always-on device that is connected to a good power source. For achieving good reliability, the LBT approach is preferable as it can avoid collision by sensing the medium.  
In this part, we present a comparison between two different LoRa MAC protocols, pure-ALOHA and LBT-ALOHA. In the LBT-ALOHA, LBT performs channel activity detection (CAD) to detect any ongoing transmission in the medium before starting a transmission. If a preamble is detected during CAD, it performs exponential random back-off until the channel is free to avoid a collision. In this evaluation, we used the SDR scenario because it facilitates a longer transmission time suitable for  
Figure 6: Two network topologies for the experiment. (**a**) Topology 1: The end devices are outside the gateway coverage. (**b**) Topology 2: The end devices are inside the gateway coverage.  
showing collision problems. For the network topology, we put end-devices randomly in a single gateway coverage without a relay.  
The traffic load is represented as \(G=\lambda T_{frame}\), where \(\lambda=n/T\) is the input rate, \(n\) is the number of transmitted packets from the end-devices during simulation period \(T\), and \(T_{frame}\) is packet transmission time. There were approximately 760 packets transmitted from 100 end-devices and 8960 packets transmitted from 1200 end-devices in the simulation. The mean traffic load \(G\) is 0.1 and 2.1, respectively. In this case, a higher \(G\) represents a higher traffic load.  
It is well known that the capture effect, a phenomenon that a strong signal can survive in a collision by suppressing other weaker signals when overlapping at a receiver, can increase the overall packet delivery ratio (PDR) in LoRa communication [5; 38]. Our simulation results also support it. As shown in Figure 7, the pure-ALOHA protocol with the capture effect has a higher PDR than that without the capture effect that is denoted as a simple model.  
As the LBT-ALOHA can reduce the probability of collision through CAD, we can expect that the reliability of the LBT-ALOHA would be higher than that of the pure-ALOHA. As conforming to the expectation, our simulation results show that the PDR of LBT-ALOHA is higher than that of pure-ALOHA by approximately 12%. We applied the LBT-ALOHA with the capture effect in our simulations below.
###### Abstract  
Mitral annular calcification is a chronic and degenerative process of the fibrous base of the mitral valve. Surgical management of mitral valve dysfunction with severe annular calcification remains technically demanding and, to date, the preferred approach is still a standard full sterotomy. We aimed to analyze and report our experience with mitral valve surgery addressing annular calcification via the minimally invasive approach through a right mini-thoracotomy. Data of patients with mitral valve disease and underlying annular calcification undergoing minimally invasive surgery from 2018 to 2022 were prospectively collected and retrospectively analyzed. The severity of mitral annular calcification was categorized with an angio-computerized tomography scan analysis as mild, moderate or severe according to calcium thickness, calcium distribution, and trigone and leaflet involvement using the Mitral Annular Calcification Computerized Tomography-score. During the study period, 27 patients with mitral valve disease and associated mitral annular calcification were enrolled. The most common etiology was advanced Barlow's disease, which was encountered in 18 cases (67%). Mitral valve replacement was performed in 21 patients (78%). No intraoperative death, atrioventricular disruption, or circumflex coronary artery injury occurred. Conversion to sterotomy was necessary in a single case. Residual moderate periprosthetic leak requiring early reoperation and permanent heart block mandating permanent pacemaker implantation were reported in one and in three patients, respectively. No cases of stroke were reported. Two patients died, accounting for a 7.4% perioperative mortality. At a median follow-up of 9 months, one patient had residual moderate mitral regurgitation, whereas two patients required short-term reoperation and prosthetic valve (re)replacement. Minimally invasive mitral valve surgery via right mini-thoracotomy should be considered an and effective approach to be indicated also in patients with mild-to-severe mitral annular calcification. Routine angio-computerized tomography scan during work-up is a mandatory step to stratify the anatomical extension and severity of the mitral annular calcification.  
Keywords: mitral valve; minimally invasive cardiac surgery; mitral annular calcification; Barlow's disease; mitral valve repair; mitral valve replacement; mitral valve prolapse; cardiac rupture +
Footnote †: journal: Applied Sciences
# Journey Planning Algorithms for Massive Delay-Prone Transit Networks +
## 1 Introduction
### Motivation  
The fastest solutions to the journey planning problem with respect to query time are those in References [13; 14]. Of them, the one in Reference [13] relies on an algorithmic framework referred to, in the following, as Public Transit Labeling (PTL). Such a framework employs a heavy preprocessing phase of the input data to speed up the query algorithm at runtime. This allows to obtain query times that have been experimentally observed to be, on average, the smallest among all known techniques, including RAPTOR, CSA and their variants. Such behavior have been observed on all meaningful real-world inputs that have been tested, including continental sized networks and the method has been shown to scale very well with the networks' size [13].  
In more details, ptl consists of three main ingredients: (i) the well-known time-expanded graph model to store transit networks (see e.g., Reference [9]); (ii) a labeling that is a compact representation of the transitive closure of the said graph, computed via a (time-consuming) preprocessing step; (iii) an efficient query algorithm exploiting both the graph and the precomputed labeling to answer quickly to queries of interest at runtime.  
On the one hand, the approach outperforms all other solutions in terms of query time and it is general and widely applicable, since several variants of the three mentioned components exist to manage a variety of meaningful application scenarios, including being able to answer to both profile and multi-criteria queries. On the other hand, unfortunately, ptl has the major drawback of not being practical in dynamic scenarios, that is when the network can undergo to unpredictable updates (e.g., due to delays affecting the route traversed by a given vehicle). In particular, even after a single update to the network, queries can return arbitrarily incorrect results, since the preprocessed data can become easily outdated and hence may not reflect properly the transitive closure. Note that recomputing the preprocessed data from scratch, after an update occurs, is not a viable option as it yields unsustainable time overheads, up to tens of hours [13]. Since transit networks are inherently dynamic (delays can be very frequent), the above represents a major limitation of ptl.  
Dynamic approaches to update graphs and corresponding (compact) representations of transitive closures have been investigated in the past, in other application domains, due to the effectiveness of such structures for retrieving graph properties [15; 16; 17; 18; 19; 20; 21; 22]. However, none of these can be directly employed in the ptl case, where time constraints imposed by the time-expanded graph add a further level of complexity to the involved data structures.
# Current Status of HbA1c Biosensors
## 1 Introduction
Although the IFCC reference method can provide precision and accuracy for HbA1c measurement [16], the needs for sophisticated equipment and the professional personnel to operate the system limit its accessibility to only large medical organizations or research institutions [17]. Therefore, it is valuable to develop methods that are easy to operate and cost-effective, but robust enough for clinical use. HbA1c biosensors have great potential for the design of analytical devices with appropriate sensitivity, low cost, simplicity, and possibility for miniaturization. Recently, several very good review articles have summarized a wide range of methods being used for the determination of glycosylated proteins including HbA1c [18; 19; 20; 21; 22; 23]. In this review, we summarize recent progress in the development of HbA1c biosensors from several aspects, including the prototypical methodology for HbA1c measurement, applications in whole-blood sample analysis, and the development of point-of-care (POC) technology in this research field, including non-invasive biosensors for diabetes.
# Tracing Student Activity Patterns in E-Learning Environments: Insights into Academic Performance
## 3 Methodology and Results
### Students' Targeted Navigation in Moodle and Final Grades  
In this study, the main aim was to correlate the learning path that students can follow by navigating the Learning Management System, provided by the institute, and their academic performance. We explored how eigenvectors might encode forum engagement, including the distribution of a student's participation over time--whether it is consistently maintained or concentrated within certain periods. These elements could influence a student's interaction with course content and, consequently, their overall academic performance. By examining these vectors alongside module grades, we aimed to reveal insights into the role of online forum participation in academic success. Figure 2 demonstrates the distribution of the students' final grades in the specific module for the academic year 2021-2022. According to this graph, the students' performance is at a very satisfactory level, since there is a high concentration of grades around 8 to 10, with fewer grades below that range (mean average 7.91 \(\pm\) 1.34).  
To further illustrate our methodology, we chose an indicative sample, comprising five students with the highest final grades and five students with the lowest final grades in the module. Table 3 displays their final grades, their eigenvectors, as well as the maximum and minimum probabilities observed within these eigenvectors.  
It is noteworthy that, although being in the Glossary state involves accessing the educational material, the possibility of visiting this resource seems to be extremely low (with the highest probability value being around 0.059). This very low probability of visiting these resources could imply that students are not engaging with or utilizing the Glossary feature, effectively. This could suggest a lack of interest in or understanding of the educational materials available in the glossary, or perhaps they are obtaining the necessary information from other sources. Additionally, it could indicate a need for further clarification or promotion of the Glossary as a valuable resource for learning within the Moodle platform. Regardless of their academic performance level, students seem to be indifferent to engaging with the study material. This data should be taken into consideration by both program designers and Moodle developers, given that the educational material and its interaction form the cornerstone of distance learning.
# A Novel Time Delay Estimation Algorithm for 5G Vehicle Positioning in Urban Canyon Environments
## 4 Simulation Results
### Analysis of the Impact of Estimation Error of Delay and Amplitude of NLOS Signal  
In the NC-MUSIC algorithm proposed in this paper, the accuracy of NLOS cancellation impacts the final delay estimation accuracy, so we analyzed the impact of NLOS delay estimation accuracy and NLOS amplitude estimation accuracy on the final delay estimation accuracy, and we use the  
Figure 10: The spectral function of NC-MUSIC algorithm in TR38.901 channel model.  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Parameters** & **Values** \\ \hline Scenario & UMa \\ Carrier frequency & 3.5 GHz \\ Bandwidth & 100 MHz \\ Subcarrier spacing (kHz) & 30 kHz \\ Transmit power & 23 dBm \\ Base station noise figure & 5 dB \\ UE noise figure & 9 dB \\ Pts & 4 \\ \hline \hline \end{tabular}
\end{table}
Table 9: The parameters of the simulation system.  
channel model in Section 4.3 for simulation experiment. The simulation results are shown in Figure 11, where the unit of error in NLOS signal delay estimation is ns and the unit of error in NLOS signal amplitude estimation is the true NLOS signal amplitude in the channel model.  
As can be seen from the figure, when the delay estimation error and amplitude estimation error of NLOS signal are within a certain range, the algorithm can still effectively provide high-precision delay estimation, but when the delay estimation error and amplitude estimation error of NLOS signal are large, the signal will not only fail to eliminate the non-line-of-sight error, but also introduce multipath when subtracting the erroneous NLOS signal, making the delay estimation accuracy decrease.
# A Survey on Hardware Accelerators for Large Language Models
## 4 CPU- and GPU-Based Accelerators
### LightSeq2  
In 2022, [PERSON] et al. proposed a series of GPU optimizations to accelerate training for a general family of Transformer models on GPUs, called LightSeq2 [20].  
LightSeq2 proposes three techniques for the acceleration of the training of Transformer networks. Firstly, for all types of Transformers, LightSeq2 uses fused kernel operators for both the encoder and decoder layers. Adjacent fine-grained element-wise kernels are fused into one coarse-grained kernel, resulting in fewer kernel launches and intermediate results. For example, the last kernel of the self-attention layer implements bias adding, dropout, and residual kernels with only one kernel launch.  
LightSeq2 also applies mixed-precision updates for training. During the initialization of the trainer, LightSeq2 copies all pieces of parameters/gradients into one tensor. Thenit resets and links them as fragments of workspace. During each training step, LightSeq2 only executes the trainer kernel once to update the workspace, which prevents launching a huge number of fragmented GPU kernels on every parameter/gradient piece.  
Finally, LightSeq2 reduces the memory footprint by minimizing memory allocations and releases, at no extra cost. LightSeq2 divides GPU memory into permanent sections with fixed sizes for storing parameters and gradients, and temporary sections with variable sizes for storing intermediate tensors.  
The performance evaluation shows that LightSeq2 is consistently faster (1.4-3.5\(\times\)) than previous systems on different GPUs and can achieve up to a 3\(\times\) speedup on large public datasets.