esa-sceva/satcom-chunk-collection huggingface dataset:
# Optimized Score Level Fusion for Multi-Instance Finger Vein Recognition
## 1 Introduction  
Biometrics is a system that recognizes an individual from the measurements of the individual's characteristics. These characteristics, also known as \"biometric traits\", are separated into physiological or behavioral characteristics. Biometrics has the properties of better user convenience, security, and non-repudiation as the biometric traits are harder to forge, misplace, and share. Among the various hand-based biometrics, the finger vein is particularly secure for personal recognition purposes since the vein structure is hidden inside the finger, making it hard to spoof and perturb.  
In general, biometrics can be subdivided into unimodal or multimodal biometrics, depending on the number of biometric traits used. Multimodal biometrics inherently requires a way to combine or fuse the multiple biometric traits used. There are several fusion methods involved for multimodal biometrics: decision level, score level, feature level, and image level, with the amount of information retained increasing and the ease of fusion decreasing in each subsequent fusion level [1]. Among the different fusion strategies, score level fusion is commonly preferred to achieve a balance between ease of fusion and the sufficient amount of information retained to distinguish between a genuine and an impostor case [2].  
In this paper, we present a multimodal biometric approach that integrates finger vein features from multiple fingers for personal recognition. Score level fusion is adopted to fuse the finger veins feature set extracted from the histogram of oriented gradients (HOG) [3]. Specifically, HOG is first used to extract the feature from each preprocessed finger vein instance. This is followed by two proposed optimized score level fusion methods: Bayesian optimized support vector machine (SVM) score fusion (BSSF) and Bayesian optimized SVM based fusion (BSBF) for multi-instance finger vein recognition. The rest of the paper is organized into different sections as follows: Section 2 revisits scientific reviews related to the methods of finger vein recognition and score level fusion, while Section 3 outlines the research focus and contribution of this paper. On the other hand, Section 4 presents proposed methods based on the Bayesian optimization approach. It is then followed by experimental analysis to vindicate the proposed solutions in Section 5. The paper is concluded in Section 6 to recap the research finding and possible future works.
# Flow Sensing-Based Congestion Detection for D2D Streaming on a 5G gNB
## 3 System Model
### Detecting Link Flow Errors
#### 3.2.1 Detecting Link Underflow Errors  
To detect whether the buffer cache suffers from the link underflow error between \(DUE_{buffer}(x)\) and \(DUE_{buffer}(x)\), a local cache for \(DUE_{buffer}(x)\) detects an encoding rate and a decoding rate. In the local buffer cache, if the decoding rate is less than the encoding rate, the buffer cache suffers from congestion owing to latency and retransmission. Therefore, in order to prevent link problems due to an underflow error between \(DUE_{buffer}(x)\) and \(DUE_{buffer}(x)\), an FV is assigned in three steps. Step-1 is set to \(\text{FV}\leq 0.5\), and Step-2 involves setting to \(0.6\leq\text{FV}\leq 0.7\). Finally, Step-3 involves setting to \(\text{FV}\geq 0.8\). If the flow source rate between \(DUE_{buffer}(x)\) and \(DUE_{buffer}(x)\) does not satisfy the link underflow error, \(S(x)\) is assigned to the minimum channel bandwidth. If \(S(x)\) does not violate the flow source rate, the buffer cache for \(DUE_{buffer}(x)\) will not suffer from the congestion due to error in flow source rates.  
Therefore, Equation (6) defines \(LC_{underflow}(x)\) to prevent the link congestion die to a link underflow error.  
\[LC_{underflow}(x)=\sum_{x=0}^{k}\left[\left\{\frac{f(x-t+s(x)}{CBW(x-1)} \right\}+\left\{E_{r}(k)-Burst(x)\right.\right] \tag{6}\]  
where \(CBW\) is the channel bandwidth for the flow rate, and \(E_{r}(k)\) is the encoding rate for \(DUE_{buffer}(x)\).
# Progress and Summary of Photodarkening in Rare Earth Doped Fiber
## 3 Phenomena and Problems Caused by Photodarkening
### Change of Absorption Spectrum  
[PERSON] et al. [4] studied the absorption spectrum changes caused by PD of four different Tm-doped fibers exposed to a 1.12 \(\upmu\)m laser. The absorption spectrum changes caused by PD were mainly observed in the ultraviolet-visible part of the spectrum but extends slightly more than 1 \(\upmu\)m in the near-infrared (Figure 4). In 2007, [PERSON] et al. [1] reported the experimental results of PD and PB of Yb-doped silica fiber under 977 nm and 543 nm irradiation. The results showed that at 977 nm, the absorption of the fiber increased in the broad spectrum (400-1000 nm), and the absorption coefficient decreases at the same time near 1 \(\upmu\)m. In 2007, [PERSON] et al. [2] studied the evolution of the PD effect with time in LMA Yb-doped silica fiber. When the fiber was exposed to pump light at about 980 nm, the absorption spectrum showed an increase in the range of visible and near-infrared spectra (Figure 5).  
As shown in Figures 4 and 5, at first glance it seems that the additional loss for Tm-doped fibers caused by PD is much higher than that for Yb-doped fibers. We believe that there are two reasons why it is easier for Tm-doped fiber to generate PD than Yb-doped fiber. First of all, the energy structure of the Tm ion is more prone to the upconversion phenomenon, which produces high-energy photons to excite color centers. Secondly, their experimental conditions are different. For example, The Tm-doped fiber is core-pumped and the Yb-doped fiber is cladding-pumped in the above two experiments, which means that core-pumping can lead to higher pump energy densities for generating PD.
## 4 Discussion  
The developed device can generate pulses from 100 ns to 100 \(\upmu\)s, up to 6.5 kV and 65 A with maximum repetition rate of 5 MHz, from 4 independent and synchronized Marx modulators.  
The pulse generator was evaluated on resistive type loads connected at the HV+ and HV\(-\) terminals, from 100 \(\Omega\) to 1 M\(\Omega\). Unipolar, symmetric and asymmetric bipolar pulses were successfully generated (Figures 7-10). In addition, synchronized shifted bipolar asymmetric pulses were generated in Figure 10. For all reported pulses, rise and fall times were in the order of 30 ns, which allowed for the generation of almost rectangular pulses.  
The maximum energy stored energy in the Marx modulators, for input voltage of 820 V, is 2 J, enabling the generation of 6.5 kV and 65 A with almost 950 ns, for voltage droop less than 10%, and burst repetition rate up to 250 Hz.  
While there are pulsed generators reported in the literature that can generate high-voltage and high-frequency asymmetric bipolar pulses [12; 13; 14; 15]. The main innovation of the presented generator is the ability to generate, also, two synchronized asymmetric pulses, and so extending the possibilities for new research progresses [16; 17; 18], due to the 4 independent Marx modulators, operated synchronously.  
Finally, the current protections described, slow and fast, seen in Figure 11, contribute to the reliability of the generator, the safety of the application, mainly for long pulse operation, being adjustable by software, which is not seen to this extend in the literature for this type of pulse generator.  
Conceptualization, A.K., L.R. and A.G.P.; methodology, A.K., U.S. and L.R.; software, U.S.; validation, A.K., L.R. and A.G.P.; formal analysis, A.K., U.S., L.R. and A.G.P.; investigation, A.K., L.R. and A.G.P.; writing\(-\)original draft preparation, L.R. and A.K.; writing\(-\)review and editing, L.R. and A.K. All authors have read and agreed to the published version of the manuscript.  
EnergyPulse Systems.  
Not applicable.  
The data presented in this paper is available on request from the corresponding author. A.K., L.R., U.S. and A.G.P.  
The authors declare no conflict of interest.
# Collecting Sensed Data with Opportunistic Networks: The Case of Contact Information Overhead
## 4 An Algorithm for Reducing Contact Information Overhead
### Overview of PoiFord
**Phase 2. ** The second phase is concerned with identifying nodes for which contact information needs to be maintained in the form of encounter history. POI information is included in summary vectors, which nodes first exchange when they encounter each other. This allows nodes to determine relevant encounters with respect to maintaining contact information. Concerned nodes keep record of an encounter only when they have mutual POIs. The major challenge in this phase is how to identify mutual POIs of a node pair, knowing that the likelihood of finding exactly the same set of GPS locations on two nodes is low. To address this, we propose PoiEncounters, a mechanism that seeks for mutual POIs of encountered node pairs, and if they are found, maintains a history of the encounter without any transitive property. This minimizes the amount of contact information and knowledge required to make forwarding decisions. In addition, since nodes are only concerned with relevant encounters, the frequency of updating contact information is reduced. PoiEncounters is flexible in the sense that it can be incorporated into existing encounter-based routing protocols. Figure 1: Functional block diagram of PoiFord. **Phase 3. ** The third phase is concerned with determining suitable nodes to forward the message. Without a transitive property, and since nodes maintain encounter history of only relevant encounters, knowledge about the network is limited. Hence, the major challenge in this phase is determining suitable nodes with less knowledge about the network. To address this, we propose PoiUtility, a forwarding utility that determines nodes that either have better chances of delivery or can make better progress towards the destination. The forwarding utility is acquired from two utilities: one that determines suitable relays from the available encounter history; and another that determines nodes capable of carrying the message spatially closer to the destination, in order to compensate for the lack of a transitive property. The following assumptions are made in the design of PoiFord: (i) each node is a smart mobile device and is equipped with a Global Positioning System (GPS); (ii) nodes are collaborative and willing to participate in routing; and (iii) source nodes have the necessary information for destinations, which are node ID and location-based information in this case.
# Ferroelectric Materials: A Novel Pathway for Efficient Solar Water Splitting
## 5 Conclusions and Outlook  
Interest in solar water splitting is on the rise, which is in line with a general trend of increasing environmental awareness. Based on state-of-the-art reports, amazing progress in solar water splitting has been demonstrated, including the upgrade of systems, and the development of new electrode materials and their structure. To perform high-efficiency solar water splitting, the materials used in the different systems have to satisfy three conditions. They should have: an appropriate bandgap energy, a suitable position of the bandgap, and chemical stability. The ideal material has a bandgap of approximately \(\sim\)2.0-2.2 eV, which can absorb about 40% of the total incident sunlight. The conduction band (CB) and valence band (VB) of the materials should be higher--between the water reduction level and below the oxidation level of water--in order to induce the water decomposition reaction. At present, no materials have been identified that meet all of the requirements for water decomposition reactions.  
In this review, we introduced various ferroelectric materials for solar water splitting with high STH efficiency. Ferroelectric materials have been known to be very stable and strong for chemical and physical applications, and their bandgap could be narrowed by doping and/or substitution. Even though solar water splitting systems with ferroelectric materials are the newest technology and have attracted important new research into hydrogen generation, until now, there has not  
Figure 11: Combination of the perovskite tandem cell with NiFe DLH/Ni foam electrodes for water splitting, **(a)** Schematic diagram of the water-splitting device, **(b)** A generalized energy schematic of the perovskite tandem cell for water splitting [211]. Copyright from 2014, American Association for the Advancement of Science.  
yet been much research performed on ferroelectric materials for use in water-splitting systems. Solar water-splitting systems with ferroelectrics are expected as significant advances in the process of hydrogen generation, with high STH efficiencies compared to other materials.  
[PERSON] had the main idea for the article. S.K., [PERSON] performed the literature search and the writing of the manuscript in consultation with [PERSON]. All authors discussed the concept of review and commented on the manuscript.  
This research was supported by the Korea Electric Power Corporation. (Grant number: R17 XA05-10) and Creative Materials Discovery Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT (2017M3D1A1040828), and by the grants from the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT, and Future Planning (NRF-2016R1C1B1014649)  
The authors declare no conflict of interest.
## 3 Results and Discussion
### Effect of Adsorbent Dosage  
Figure 4 presents the removal of Pb(II) by G-26 and MTS9570 as a function of resin dosage. Resin dosage was varied from 5 to 30 g/L, while other conditions were the same as in the adsorption time tests. Increasing resin dosage increased the removal percentage of Pb(II). When the resin dosage increased to 25 g/L, Pb(II)-removal rates were close to 100% for both resins. This indicates that both resins can be used as adsorbents to remove Pb(II) ions effectively, and 25 g/L resin dosage was used for subsequent tests.  
Figure 1: Resins with high removal rate of Pb (II) at 30 min contact time, 150 rpm agitation speed, 20 mL volume, pH 4.5, concentration 1000 mg/L, and temperature 20 \({}^{\circ}\)C. (**a**) Purolite S940, Lewatit monoplus TP207, Amberlite IR-120H, Dowex G-26, Purolite S930 plus, Amberlite IRC7841, and Purolite S950 plus resin. (**b**) Lewatit monoplus TP208, SIR 500, Lewatit MDS TP220, Purolite WTS 9570, MBD-15-SC, and Amberlite IRC747 resin.  
Figure 2: Resins with low removal rate of Pb (II) at 30 min contact time, 150 rpm agitation speed, 20 mL volume, pH 4.5, concentration 1000 mg/L, and temperature 20 \({}^{\circ}\)C.
## 2 State of the art  
The design of distributed multimedia applications, such as systems for access to remote multimedia databases or teleconferencing, requires careful consideration of quality of service (QoS), because the presentation quality of live media, especially video, requires relatively high utilization of networking bandwidth and processing power in the receiving systems. For applications running in a sharedenvironment, the allocation and management of these resources is an important question, although most existing systems are based on a best-effort approach [7]. Due to their real-time characteristics, multimedia sessions need quality guarantees from the network [3]. A major quality of service (QoS) requirement for real-time media is to deliver packets reliably to the end receiver(s) and in a timely fashion. The estimation of the current quality is necessary to determine the operating settings for acceptable error probability and signal-to-interference ratio (SIR) target level [8]. In UMTS environments, this quality control is implemented by means of inner and outer loop power control. In particular, our technique aims to infer with this latter mechanism of quality measure (_i.e._ the outer loop power control).  
Traditionally, one of three techniques has been used for error-control: automatic repeat request (ARQ, and Hybrid ARQ in UMTS applications) which uses acknowledgments, time-outs, and retransmissions; forward error correction (FEC); and error concealment (EC) at the receiver [9]-[11]. In addition, for a teleconferencing application involving many users, a single quality of service level may not be appropriate for all participating users, since some users may participate with a very limited local workstation which cannot provide for the quality which is adopted by the majority of the conference participants [5]. Consequently, multimedia content processing has employed new paradigms that include distributed, cooperative, and resource-constrained models, whereas multimedia communications have addressed the new application challenges by focusing on cross-layer design [12]-[13]. With few exceptions, such as joint source channel coding and adaptive streaming, processing of multimedia content has been approached as a network-independent problem by the research and academic communities [14]-[15]. In turn, the works that addressed the content delivery aspects have typically not included the characteristics of the source content and have primarily studied interactions among lower layers of the protocol stack [16]. However, the processing and delivery of multimedia content are not independent and their interaction has a major impact on the QoS aspects. QoS is designed to hide low-level application variation and provide necessary service guarantees [2]. In particular, tracing watermarking (already thought for Copyright Protection purposes) has been recently proposed as a technique to provide a blind measure of the QoS of the communication link by means of an unconventional use of digital watermarking [5].
## 2 Materials and Methods
### Experimental Setup  
The experimental setup is shown in Figure 3. A continuous wavelength, single longitudinal mode laser diode with a center wavelength at 405 nm is focused onto a PP-KTP (KTiOPO\({}_{4}\)), type II crystal. Entangled photons centered at 810 nm are generated via Spontaneous Parametric Down-Conversion SPDC. Entangled photon pairs have orthogonal polarization and are emitted in a semi-colinear configuration with the pump. A dichroic mirror (DM) transmits SPDC photons and reflects the pump photons. At the polarizing beam splitter (PBS), the down-converted photon pairs are separated by polarization into the two arms of a Mach Zehnder interferometer.  
The s-polarized photons are directed towards a moveable delay mirror (M1). The (M1) mirror is scanned along the direction of propagation during the experiment to match the path length of the other sample arm, preserving indistinguishability and ensuring interference of entangled photons. S-polarized photons are reflected from the PBS and directed into a single mode, non-polarizing 50:50 fiber optic coupler.  
The horizontally polarized sample arm photons are transmitted through the first PBS and directed towards a non-polarizing beam splitter (NPBS). The NPBS has a 50:50 reflection/transmission ratio and transmits half of the entangled photons toward a mirror  
Figure 3: Experimental setup for Polarization-Sensitive Quantum Optical Coherence Tomography.  
Figure 2: Quantum Interference with polarization projection of signal and reference photons between 0 and 1.  
(M2). A microscope slide with the biological tissue is placed against the (M2) mirror for transverse plane scanning. The QWP converts the polarization of the photons into circularly polarized photons, followed by a 20 mm focusing lens. The sample and mirror combination reflects photons towards the NPBS, where they are directed into a single mode, non-polarizing 50:50 fiber optic coupler. The photons from the delayed and sample arms are recombined in the fiber optic coupler. The delay arm mirror is scanned along the direction of propagation to match the path length of the sample arm. When entangled photons between two arms are indistinguishable in propagation path and polarization, quantum interference is observed using a coincidence circuit. Two single photon counting modules, along with the coincidence circuit (denoted \(\otimes\)), measure the coincidence rate of the entangled photons.
# Influence of Cavitation and Shaft Deformation in the Analysis of Lubrication of the Stern Bearing
## 1 Introduction
The effect of cylinder deactivation upon engine bearing efficiency has bee studied as an application of the method. [PERSON] et al. [21] proved that the rotational speed is important in determining the cavitation boundary conditions of the oil film through theoretical and experimental studies. [PERSON] et al. [22] proposed an analytical approach to optimize the textured bearing with cavitation, and [PERSON] et al. [23] further obtained a general equation based on the incompressibility of fluids. [PERSON] et al. compared the Reynolds boundary condition with JFO theory to study the influence of cavitation theory on bearings with a stable load [24]. [PERSON] et al. established a gas cavitation model that can be applied to non-equilibrium cavitation simulation based on Bunsen solubility and bubble dynamics [25]. [PERSON] et al. proposed an efficient numerical approach for the simulation of the effects of cavitation and non-Newtonian behavior on the performance of squeeze film [26] and found that the anisotropic structure of the porous surface decreases the pressure in the porous disc [27]. The deflection of the stern shaft will inevitably affect the oil film distribution, causing changes in bearing lubrication characteristics and dynamic characteristics. [PERSON] et al. [28] proved that controlled elastic deflection of the journal bearing improves the carrying capacity of the bearing and reduces friction. [PERSON] et al. [29] investigated the effect of deflection on the load-bearing characteristics of the permanent magnet bearing and proved that deflection is a critical factor for load bearing. [PERSON] et al. investigated the influences of cavitation and different boundary conditions on the Stribeck curves of stern bearings [30]. The influence of surface roughness on the lubrication status of hydrodynamic bearings is also important. Generally, the effect of surface roughness is treated as a random variable [31], while the contact and lubrication model with micro-convex, which can be modeled through surface scanning, gives a more accurate description of contact force. [PERSON] et al. conducted a comprehensive survey of hydrodynamic bearings and investigated the influence of rough surfaces in big-end bearings [32]. They also discussed the influence of different roughness patterns. The transverse, longitudinal, and isotropic roughness patterns in bearings were considered. In this paper, based on the cavitation algorithm of mass conservation and the introduction of the micro-convex contact model, a mixed lubrication model of bearings considering shaft deflection and cavitation effect is established. The influence of cavitation and shaft deflection on the lubrication state is analyzed. The proposed algorithm presents a numerical model considering the property of liquid film, the deformation of bearings, and surface roughness. The fluid-solid coupling effect in bearing deformation, asperity contact, and film pressure are investigated. The proposed algorithm is suitable for describing the behavior of lubricated journal bearings.