esa-sceva/satcom-chunk-collection huggingface dataset:
## 2 Related Work
### Traditional Approaches  
Traditional methods such as collaborative filtering (CF) [8; 9] and matrix factorization (MF) [10; 11] have long served as foundational techniques in location-based social network (LBSN) recommendations. CF-based approaches typically model user preferences by leveraging behavioral similarities among users or items. For instance, [PERSON] et al. [8] integrate short-term sequential transitions and long-term personalized preferences through a latent factor model, effectively capturing spatio-temporal dynamics and individualized patterns for next-location prediction. Meanwhile, the ICCF model [9] enhances CF by incorporating semantic features and implicit feedback, utilizing a confidence-weighted framework to mitigate cold-start challenges and extract meaningful patterns from heterogeneous data sources such as user demographics and textual content. On the other hand, MF-based methods aim to decompose the user-item interaction matrix into low-rank latent spaces. GeoMF++ [10] introduces spatially aware latent factors through grid-based modeling to jointly learn user preferences and geographical influences, demonstrating strong scalability and robustness to sparsity. Similarly, SQPMF [11] unifies social trust, transition behaviors, and personalized preferences within a probabilistic matrix factorization model, leveraging contextual and sequential cues to enhance location prediction accuracy. Despite their effectiveness, these traditional approaches often struggle with modeling complex higher-order relationships and disentangling multifaceted user intents, motivating the development of more advanced representation learning techniques.  
While some traditional trip choice models (e.g., discrete choice models, gravity models, and agent-based simulations) typically rely on predefined utility functions and require extensive feature engineering or domain-specific priors, our method is data-driven and leverages graph-based representation learning with self-supervised contrastive signals. Moreover, unlike transport system models (TSMs) [32; 33] that focus on macroscopic travel flows, our model aims at personalized, fine-grained next-location prediction in location-based social networks (LBSNs), which emphasizes individual behavioral signals, rather than aggregate transportation flows.
# A Wideband Reflectarray Antenna for Satellite Application with Low Cross-Polarization
###### Abstract  
A double-layer element consisting of a spider-shaped structure on the top layer and a pair of concave arms with a circular ring on the middle layer is proposed for the wideband reflectarray with low cross-polarization characteristics. The unit cell offers a linear and wider phase range of 800\({}^{\circ}\). Based on the proposed unit cell, an offset-fed reflectarray with an octagonal aperture comprising 6769 unit cells is constructed at 11.725 GHz. The reflectarray offers 1 dB and 3 dB gain bandwidths of 25.2% and 32.3%, respectively, with an operating frequency range of 10-13.85 GHz. A peak gain of 31.2 dBi with an aperture efficiency of 42% is achieved. The cross-polarization levels are less than the co-polarization by 40 dB over the entire operating band.  
a _applied_  
_sciences_
## 5 Discussion  
### Effects of Spatial Information on Different Numbers of Training Samples  
The step of spatial information extraction within three features is removed, and the three groups complementary feature information is directly classified by SVM to create a fusion result for classification, while other parameters and operations remain unchanged. The corresponding classification performance is compared with the proposed MAKC on real SAR images, which is illustrated in Figure 8. It can be seen that this method has better classification performance for real SAR images, taking into account different numbers of training samples. For the SAR1, the classification accuracy decreases when spatial information extraction is removed. When only ten training samples (TN = 10) are selected for each class, the OA of the proposed MAKC method is 90.1%, while the OA of the MAKC without spatial information is 78.67%, which is shown in Table 6 with the best results in bold. It can be seen that the OA decreases by more than 10%. Because the spatial information is not extracted, the abundant detail information within each feature cannot be well exploited. The same situation can also be observed for the SAR2 and SAR3. Overall, the proposed MAKC can consistently achieve the best results in terms of classification accuracy when compared with the situation without using spatial information within features, so spatial information extraction is effective.
## 4 Analysis of Factors Affecting the Reflection Coefficient  
In Section 3, the double-layered porous ice model was verified to be correct, on the basis of which a further study was made on the factors influencing the reflection coefficient, such as frequency, porosity and ice thickness.
# The Current Development of Structural Health Monitoring for Bridges: A Review
## 5 Damage Identification Methods
### Modal Parameter-Based Methods
#### 5.1.2 Curvature Mode Shape-Based Methods  
[PERSON] et al. [127] studied the application of the CMS method to multiple damage detection. They introduced a gapped smoothing method to minimize noise. The effectiveness of the proposed method in damage location was proved by a comparison with previous studies. [PERSON] et al. [128] improved the CMS approach using the distributed genetic algorithm. The results of several laboratory tests showed that the proposed method can complete tasks of Level 3 SDI under various noise levels. [PERSON] et al. [129] introduced a difference indicator, which came from the difference between a CMS and a CMS estimation of the damaged structure, to detect the location of the damage. This method provides a new way to detect damage in structures that lack health monitoring data because it does not require complete structural data. However, only the first mode was studied. For higher modes, the computational cost and time of this method will increase.
## 6 Biliary Cancers and Gastrointestinal Stromal Tumors  
Liver cancer is a neoplasm originating in hepatocytes that is characterized by its intrinsic chemoresistance. It is the most common primary liver neoplasm and the fifth leading cause of death worldwide. Among the risk factors for its appearance are alcoholic cirrhosis, chronic infection by hepatitis B and C, and exposure to aflatoxin. In the early stages, treatment is based on surgery, radiofrequency ablation/thermoablation, or chemo/radioembolization. In the advanced stages, given its intrinsic chemoresistance, treatment is performed using multikinase inhibitors of tumor angiogenesis such as sorafenib and lenvatinib [85].  
There are various in vitro studies in which natural bioactive compounds are used in order to reverse drug resistance mechanisms. [PERSON] et al. described compounds derived from Annonaceae (in this case from Uvaria Acuminata) known as acetogenins, which are fat-soluble polyktetide compounds. These compounds significantly decreased the expression of MDR1 mRNA (P-gp) in the HepG2 hepatocellular carcinoma line and that of MRP1 in the BEL-7402 line [86]. Another study by [PERSON] et al. (2011) refered to the effect of dioscin, a steroidal saponin, on the sensitization of HepG2 hepatocarcinoma cells to adriamycin when they presented high levels of expression of MDR1 (P-gp) [87].  
Cholangiocarcinoma is a tumor originating in the epithelium of the bile ducts. It is associated with pathologies such as ulcerative colitis or sclerosing cholangitis. In the advanced stages, it is characterized by its poor prognosis and its moderate sensitivity to chemotherapy agents such as cisplatin, GEM, and oxaliplatin [85]. In 2014, [PERSON] et al. described two xanthones derived from Garcinia hanburyi called isomorellin and forbesione, which showed decreases of 20% and 30%, respectively, in the expression of MDR1 mRNA in the cholangiocarcinomacell line KKU-100. When these compounds were combined with DOX, said inhibitions increased up to 70% [88].  
In the case of gastrointestinal stromal tumors, no studies have been found that analyze the inhibition of the MDR system by natural compounds. This, together with the fact that there are very few studies in the case of hepatocarcinoma and bile duct cancer, opens up an exciting avenue of research with a view to carrying out new studies.
## 4 Formulation of an Operation and Maintenance Strategy for Equipment with a High Failure Rate
### Verification of Equipment Value Improvement  
In the previous section, this study obtained the external optimal operation and maintenance strategy, taking video surveillance as an example. This section introduces the theory of value engineering to verify the effectiveness of the operation and maintenance strategy to enhance the value of video surveillance equipment. The study comprehensively considers the cost factors such as time and human resources in the maintenance operation. The value coefficient of 10 sets of video surveillance equipment in the 3 sections involved in the study is calculated to verify the improvement of the value of this kind of equipment according to the basic formula of value engineering, \(V=\frac{F}{\zeta}\). The research still takes video surveillance equipment as an example. It sets the function coefficient and cost coefficient of the equipment according to the corresponding national standards of the area where the electromechanical equipment belongs and the norms of the transportation and machinery industry to calculate the improvement in the value coefficient of the equipment before and after the implementation of the optimal operation and maintenance strategy and verifies the effectiveness of the strategy.
## 3 Results
### Effect of MLE on Morphological Attributes of Plants
#### 3.1.2 Root Length  
Figure 1B shows the effect of MLE application on the root length of wheat facing Cd stress. Results revealed that the application of 3% MLE along with combinations of 500 \(\upmu\)M and 1000 \(\upmu\)M (under light) cadmium solutions increased the root length by 17.67% and 33.20% compared to control. This increase was less under shade compared to light but was still higher Cd1000+MLE (10.73%) compared to their control under shade. More interestingly, 3% MLE with both cadmium treatments even resulted in longer root lengths compared to MLE 3% alone treatment under light.
# Acquisition and Processing of UAV Fault Data Based on Time Line Modeling Method
## 5 Experimentation
### Comparison with Related Data Sets  
#### 5.1.1 Data Information Comparison  
Table 9 highlights the significant shortage of data sets available for UAV fault detection at present. Moreover, many of the available data sets have imbalanced positive and negative samples, making them inadequate for effectively training artificial intelligence-based anomaly detection models for UAVs. In this context, the proposed TLM method offers a viable solution for obtaining UAV fault data, as well as facilitating the labeling and balancing of positive and negative samples.
# Application of a High-Power Reversible Converter in a Hybrid Traction Power Supply System
## 2 Proposed Hybrid Traction Power Supply Scheme  
At present, the traction power supply equipment installed in the traction substation is a typical 24-pulse rectifier, which is made up of two 12-pulse rectifiers. In this way, AC grid current harmonics and DC voltage ripple can be reduced, and the system redundancy can be increased.  
For diode rectifiers, DC output voltage is uncontrollable, and the energy can only be transmitted from AC to DC. In order to reuse the braking energy and reduce the DC voltage fluctuation, a high-power reversible converter is introduced into the traction power supply system. Figure 1 shows the proposed hybrid traction power supply scheme. In Figure 1, an additional reversible converter branch is added, but in Figure 1, a 12-pulse rectifier is replaced by a high-power reversible converter. It is obvious that no additional installation space is required in Figure 1. The arrows indicate the direction of the energy flow.  
No matter what kind of scheme, the reversible converter has a four-quadrant operation capability. When the train is in the traction state, the reversible converter can provide energy for the train, and reduce the DC voltage drop. When the train is in the braking state, the reversible converter can invert the braking energy back to the AC grid, and save energy. The overvoltage caused by regenerative braking can be suppressed effectively.  
Since the diode rectifier and reversible converter will work in parallel, their work characteristic must be studied, respectively, and then a coordinated control strategy should be adopted.
# Secure and Efficient Deduplication for Cloud Storage with Dynamic Ownership Management
## 2 Related Work
### Client-Side Deduplication
This approach employs a dedicated key server in the MLE key generation process to thwart indiscriminate attacks. Moreover, CSED integrates a bloom-filter-based PoW system to combat illegal content distribution. In 2020, [PERSON] et al. proposed a randomized secure user-to-user deduplication method designed to enhance storage performance in cloud computing services [21]. Clients owning identical copies of data can share the same random value through ElGamal key exchange. In 2021, [PERSON] et al. presented a reinforced PoW protocol [22]. In the proposed method, the cloud storage requests the bit positions of the CE ciphertext. The client must respond with the appropriate blocks for proof of ownership. In 2023, [PERSON] et al. introduced a novel approach called client-side deduplication with encryption key updates [23]. This technique extends the server-assisted encryption method by introducing features like uptable encryption and dynamic proof of ownership. The uptable encryption offers a mechanism to update encrypted data, simplifying the process of modifying existing information or adding new data without the need to decrypt and re-encrypt the entire dataset. Data deduplication allows for the efficient utilization of storage space, and client-side deduplication helps to conserve network bandwidth. Some approaches store ciphertext in the cloud storage for data confidentiality, while proof of ownership is conducted with plaintext. Nevertheless, these methods still remain vulnerable to poison attacks due to the inability to establish a clear relationship between ciphertext and plaintext. Recently, techniques have emerged that use plaintext transformed into MLE keys for proof of ownership. Client-side deduplication research has mainly focused on ownership proof and encryption-based deduplication. However, research that significantly reduces client-side computational overhead, as our proposed method does, has been lacking.
# Task-Driven Real-World Super-Resolution of Document Scans
## 4 Experimental Validation
### Experimental Setup
#### 4.1.1 Datasets
The Old Books dataset [45] is publicly available and comprises HR scans of historical printed documents. It features a wide variety of typographic styles, physical degradation due to paper aging, and uneven illumination. Importantly, the dataset includes text transcriptions and binarized ground truth versions of each scan, making it particularly suitable for evaluating the OCR-related performance on super-resolved outputs. To examine generalization beyond the document-centric imagery, we employ a simulated subset of the MS COCO dataset [28]. From this corpus, we extracted image regionsthat contain textual content, and we generated corresponding LR images via bicubic downsampling. This controlled setup enables benchmarking of our document-oriented SR model against natural-scene inputs, offering insights into its cross-domain adaptability. For the University Bulletin, Scientific Article, COVID Test Leaflet, and Old Books datasets, we prepared real LR inputs obtained from physical scans performed at different resolutions, as well as simulated LR-HR pairs generated by downsampling the corresponding HR images. This dual-mode evaluation facilitates fair and consistent comparison across different degradation procedures, helping to disentangle the effects of acquisition noise from purely resolution-related loss. In contrast, the MS COCO subset is included solely into the simulated dataset, as no real LR counterparts are available. The MS COCO, University Bulletin, and Scientific Article datasets were split into training and test parts without any overlaps, ensuring that there were no information leakages between training and test sets. The simulated MS COCO images were used to pretrain the model, and the images from the University Bulletin and Scientific Article datasets (both in real-world and simulated modes) were used to train the models in a task-driven way (20% of the training data were used as a validation set). The Old Books and COVID Test Leaflet datasets were not exploited for training, thus allowing for verifying the cross-device robustness of the elaborated models. All the datasets exploited in our study are summarized in Table 1. For each dataset, we present the split into training, validation, and test sets, and we provide the number of images (i.e., the original distinct pages) alongside the size and number of extracted patches in the real-world and simulated parts. For real-world datasets, each image was scanned at different DPIs to obtain LR and HR images. For the simulated images, the HR scan was downsampled to obtain a simulated LR image.
# Tripartite Quantum Key Distribution Implemented with Imperfect Sources
## 6 Simulation Results
### Discussion of Results
On the contrary, the three-party RFI protocol incorporates the encoding source flaws due to the extinction ratio of the phase modulators and the drift of the reference frames in the security analysis, reducing both the secret key rate and the transmission distance. A limitation of this work is that the quantity \(C\) is computed from average values, and time is required to accumulate enough statistics to estimate these values. Therefore, it depends on whether the frame rotation is slower or faster than the time required to estimate the value of \(C\). Consequently, it will be helpful to explore finite-key studies as a solution. However, according to the results presented above, the three-party RFI QKD is a realistic protocol that can be realized with current experimental technology without compromising the security of the QKD.
# Experimental Evaluation of Thermal Performance and Durability of Thermally-Enhanced Concretes
## 3 Results and Discussion
### Thermal Transmission  
Figure 7 and Table 7 show the thermal transmission measured by a calibrated hot box (CHB) according to ASTM C1363 and ISO 8990. NN (the specimen without the insulating materials) had a thermal transmission of 2.94 W/m\({}^{2.\circ}\)C. The values of other specimens with NWAC tended to decrease with the use of insulating materials. However, the reduction of the thermal transmission was not remarkable compared with the thermal conductivity reduction measured by QTM and GHW. For example, the average thermal transmission reduction ratio for NWAC by CHB was about 12%. From QTM and GHW, the average thermal conductivity reduction ratios were 35% and 31%, respectively. This is attributed to the difference in heat transfer conditions. QTM and GHW are related to the conductivity, relying on direct contact, while CHB is the thermal performance testing of the convection transferring from hot places to cold places using continuous circulation. For LWAC, their thermal transmissions varied from 2.27 to 2.38 W/m\({}^{2.\circ}\)C. As expected, specimens adding hollow micro-spheres had the lowest values of 2.42 and 2.27 W/m\({}^{2.\circ}\)C for NWAC and LWAC, respectively.  
Figure 7: Experimental observations of concrete thermal transmission measured by calibrated hot box (CHB).  
The trend of thermal transmission is similar with air-dry density of the thermally-enhanced concrete. Additionally, its trend is similar with the results from QTM and GHW. The reduction ratios are lower than that from QTM and GHW. Insulation materials used in this study still show their ability for enhancing the thermal performance of the concrete. In real heat transfer in buildings or houses, convection or radiation occurs and thermal transmission can offer a good measure for energy efficiency, while thermal conductivity measured from QTM and GHW only consider conduction.
# Analysis of BDS/GPS Signals' Characteristics and Navigation Accuracy for a Geostationary Satellite
## 3 BDS/GPS Signal Characteristics  
The onboard receiver has demonstrated the ability of tracking GPS and BDS signals in GEO. The flight data generated by the GNSS receiver was downloaded to the ground. In this section, we analyze the signal characteristics of BDS and GPS including observations quantity and distribution, availability, PDOP, observations accuracy.
# Benefits and Lessons Learned from the Sentinel-3 Tandem Phase
## 9 Geophysical Signal and Geometric Differences
### Impact of Viewing Geometry on OLCI Level2 Products  
During the drift phase, the distance between the satellite progressively increases, leading to different viewing conditions, as illustrated in Figure 14. Data from two dates, in particular, have been collected in the tandem optical data archive. On 22/10/2018, the along-track separation between the satellites was 3 min. While this time difference hardly affected sun illumination conditions, the difference in viewing angles ranged between 1 and 6 degrees. On 29/10/2018, the separation reached 9 min, while the difference in viewing angles was between 4 and 20 degrees. In these circumstances, it is reasonable to assume that the main differences between Sentinel-3 A and B products come from the impact of viewing conditions rather than from changes in sun illumination or target evolution (provided that the inter-calibration differences observed during the tandem phase are accounted for).  
This configuration allows us to investigate the impact of viewing conditions on the retrieval of geophysical parameters in level 2 products. Comparisons of OLCI land and water products reveal some interesting results. While the OLCI green vegetation index (OGVI) algorithm attempts to correct for bi-directional Reflectance Distribution Function (BRDF) effects, differences of 10% or more are observed for angular differences greater than 5\({}^{\circ}\). For the OLCI total chlorophyll index (OTCI) algorithm, inter-satellite differences are shown to be mainly coming from differences in spectral characteristics, highlighting current limitations of the smile correction approach (not shown). Water products (water leaving reflectances and chlorophyll concentration) are shown to be comparatively more robust to changes in viewing conditions. Examples of results are presented in Figure 15; see [23] for complete results. These findings provide meaningful guidance for the future improvement of retrieval algorithms.  
Figure 13: Repeatability of S3A and S3B tandem acquisitions above subglacial Lake Vostok, East Antarctica. Panel **a**: the locations of satellite tracks (white) and the acquisitions shown in panels **b–i** (turquoise); the background image is taken from the MODIS Mosaic of Antarctica. Panels **b–i**: co-located, contemporaneous, and co-orientated (within 150 m) tandem phase waveforms acquired by S3A (blue) and S3B (magenta), demonstrating excellent agreement between S3A and S3B acquisitions.