esa-sceva/satcom-chunk-collection huggingface dataset:
# Fault Investigation of Circulation Pumps to Detect Impeller Clogging
## 2 Materials and Methods
### Fault Detection of Pumps  
It has been shown that faulty impellers can lead to a reduction of head and flow [14]. In the case of built-in head and flow sensors, such a fault could be detected. Since circulation pumps calculate  
Figure 3: Setup for measuring the motor currents of a circulation pump.  
head and flow, these variables can be used for fault detection. However, these two variables were determined based on stored characteristic curves and a motor current measurement [6]. As the stored curves only apply to the healthy condition and the motor current was dependent on the process curve, these values cannot be used for fault detection. The change of the current consumption due to a pump fault, as shown in [15], cannot be used for the mentioned reason.  
Features that are independent of the process are more suitable. These include the amplitudes at certain fault frequencies of MCSA. When evaluating the motor current spectrum, attention must be paid to the damping behavior of the motor, which was decisively influenced by the motor inertia. The higher the frequency of a load oscillation, the stronger the damping by the transfer behavior of the motor.  
A typical frequency that can be used for fault detection is the blade pass frequency (BPF). Due to the finite number of blades, vibrations can occur, which can be seen in both vibration and current spectrum. The frequency where this component appears in the current spectrum was calculated using Equation (1), where \(k_{1}\) is a positive integer, \(N_{b}\) the number of blades, \(p\) the number of pole pairs and \(f_{s}\) the supply frequency [21]. However, Equation (1) only applies to motors without slip.  
\[f_{BPF}=\left(1\pm\frac{k_{1}N_{b}}{p}\right)\cdot f_{s}. \tag{1}\]  
Amplitudes at \(f_{BPF}\), which can also occur in the healthy condition of a pump, can be influenced by faults. In [16] it is shown, that the amplitude of the \(f_{BPF}\) component is increased in the cavitation situation. The results of [14] indicate a decrease of amplitude at \(f_{BPF}\) if the impeller has inlet and exit tip faults. The analysis should also consider the fact that the fault frequencies of \(f_{BPF}\) can be equal to the fault frequency in the case of the fault of eccentricity [22]. In [23] it is written that the wear of the impeller can influence the amplitude at \(f_{BPF}\). Furthermore, it can be seen in [23] that unbalance or misalignment can influence an additional fault frequency. These oscillations occur in the sidebands of the supply frequency, see Equation (2). In [17], it is shown that the amplitude at this frequency is influenced by the faults dry running, impeller clogging and bearing failure of a pump.  
\[f_{pump}=\left(1\pm\frac{1}{p}\right)f_{s} \tag{2}\]  
These frequencies can also be equal to frequencies of faults, which cause eccentricity [22]. This has to be considered when analyzing the data.
## A Hierarchical Multitier Approach for Privacy Policies in e-Government Environments  
**[PERSON] 1,*, [PERSON] 1, [PERSON] 2 and [PERSON] 3**  
1 Laboratory of Information and Communication Systems Security, Department of Information and Communication Systems Engineering, University of the Aegean, GR-83200 Samos, Greece; E-Mail: [EMAIL_ADDRESS]  
2 Cultural Informatics Laboratory, Department of Cultural Technology and Communication, University of the Aegean, GR-81100 Mytilene, Greece; E-Mail: [EMAIL_ADDRESS]  
3 Department of Digital Systems, University of Piraeus, GR-18534 Piraeus, Greece; E-Mail: [EMAIL_ADDRESS]  
* Author to whom correspondence should be addressed; E-Mail: [EMAIL_ADDRESS]; Tel.: +30-22730-820-00; Fax: +30-22730-820-09.  
Academic Editor: [PERSON]  
_Received: 11 August 2015 / Accepted: 9 December 2015 / Published: 21 December 2015_  
**Abstract:** The appeal of e-Government users to retain control over their personal information, while making use of advanced governmental electronic services through interconnected and interoperable deployments, can be assisted by the incorporation of privacy policy and Preferences documents. This paper addresses the formulation of light-weight and accurate privacy policies, while preserving compliance with underlying legal and regulatory framework. Through the exploitation of existing governmental hierarchies, a multitier approach is proposed able to support diverge data needs and processing requests imposed by service providers. The incorporation of this approach into e-Government environments will reduce the administrative workload, imposed by the inclusion of privacy policy documents, and promote the implementation and provision of user-centric and data privacy aware electronic services.  
**Keywords:** e-Government; privacy policy; hierarchy; privacy preferences
## 3 Methods
### High-Quality Crop-Specific NDVI Time-Series Reconstruction  
To effectively reconstruct high-quality crop-specific \(NDVI\) time series profiles, two facts are noteworthy in this regard. First, \(NDVI\) is often underestimated for noises such as atmospheric effects. Second, vegetation growth typically remains stable, exhibiting gradual changes in the absence of disturbance. Even abrupt events such as crop harvesting can cause sudden decreases in the \(NDVI\) values, introducing fluctuations in the \(NDVI\) time series. However, occurrences where an observation shows a sharp drop shortly followed by a rapid increase, forming a deep V-shape, are quite rare. Therefore, instances of consecutive sudden decreases and increases in a time series are primarily considered noise. Considering these assumptions, the objectives of the proposed UE-WS method are to more effectively handle noisy observations, improve the accuracy of \(NDVI\) data reconstruction, and maintain the integrity of multi-temporal \(NDVI\) profiles so that they accurately reflect the natural growth stages and seasonal variations of the studied crops. There are two main steps to achieve these goals using the UE-WS method (Figure 2). We first extract the upper envelope nodes of the \(NDVI\) time series in the backward and forward directions, then smooth the retrieved upper envelope to minimise the influence of residual noise.
# Effects of Freeze-thaw Cycles on the Mechanical Properties and Microstructure of a Dispersed Soil
## 3 Result and Discussion  
### Soil Sample Dispersion Identification Test  
#### 3.1.1 Pinhole Test  
The pinhole test involved subjecting the soil samples to a water pressure of 50 mm head to observe the erosion of small holes and the flow and turbidity of water. The degree of soil dispersion was determined according to the specifications [29]. The pore size obtained from the pinhole test, as shown in Figure 3, is considered a reliable indicator for determining the dispersibility of soil samples [33]. It provides valuable information about the soil's ability to resist erosion under specific hydraulic conditions. The dispersion of each soil sample was evaluated based on the identification criteria, and the outcomes of the pinhole test are displayed in Table 3, indicating the level of dispersibility of each sample.  
For a more comprehensive comprehension of the alterations in dispersibility, the final flow rate and pore diameter curves were constructed for all highly dispersible soil samples, depicting their evolution relative to the number of freeze-thaw cycles. As depicted in Figure 4a,b, both the final flow rate and pore diameter exhibit an ascending trajectory with an augmentation in the number of freeze-thaw cycles. This trend signifies a gradual amplification in dispersibility. The outcomes of the pinhole test unveil that with the  
Figure 3: Final pore diameter of dispersed soil after different numbers of freeze–thaw cycles (where “F–T n” indicates the quantity of freeze–thaw cycles).  
escalation of freeze-thaw cycles, the soil's structure experiences progressive deterioration, leading to a weakening of inter-particle cohesive forces and subsequent reduction in the soil's resistance against water erosion. Furthermore, under identical hydraulic conditions, the soil sample's final pore size and effluent turbidity are gradually augmented.
# Determination of pH in Powdered Concrete Samples or in Suspension
## 1 Introduction
More accurate measurement of pH values in concrete have been achieved by various methods including: (a) a flat-surface electrode system in combination with filter paper [15], (b) a sensor based on a three-electrode electrochemical test [16] and (c) Ag/Ag\({}_{2}\)O sensors manufactured using a screen-printing process, which demonstrated good response time and reproducibility [17]. Further, a technique for measuring the free chloride concentration and pH value of mortar specimens was reported in [18] based on several Ag/AgCl ion-selective and iridium/iridium oxide electrodes. X-ray diffraction and thermogravimetric analysis [19] and the electrochemical impedance spectroscopy method [20] have also been developed. The latter method was time efficient, and was applied to analyse concrete samples exposed to a marine environment at five different pH values [21]. All the above-mentioned methods have unique advantages and drawbacks and it is clear that there is a need for efficient and accurate devices for measuring the pH of concrete, including in the binary form to distinguish pH-High (in the secure zone) from pH-Low (in the dangerous zone), as a first step in development of a new measurement procedure. The portable sensor platform is of particular interest to professionals engaged in inspection jobs and can help experts to take appropriate decisions about interventions and remedial work on time. This article presents two sensors, one for measuring the pH of ground concrete powder in a suspension, and another one using the same powdered concrete, but dry, which are important from not only a scientific point of view, but also from a commercial point of view. Both sensor platforms were fabricated using cost-effective xurography technique. This method creates multi-layered structures, laminating separate transparent and mechanically flexible polyvinyl chloride (PVC) foils and using gold leaf as a conductive material. The first sensor platform is a microfluidic device which works on the principle of parallel capacitive electrodes. Concrete powder suspended in distilled water was injected into microfluidic channels between the two gold electrodes of a capacitor. The second platform is an interdigitated capacitive planar electrode system. Concrete powder was dispersed onto the upper side of the electrodes, changing the total capacitance of this structure in a pH-dependent manner. Electrical characterization of both sensor platforms was performed using an Impedance Analyzer.
## 6 Example Analysis  
The effectiveness of multi-DC modulation coordination optimization strategy is verified by taking the power grid of a region after back-to-back DC projects are put into operation.  
After back-to-back DC projects are put into operation in a certain region, all the connections between the power grid and the external power grid will be realized through the DC network, as shown in Figure 4. The dashed line box in the figure represents the synchronous power grid. A hybrid AC-DC network containing a high voltage direct current transmission (HVDC) system is taken as the main research object. Regardless of the influence of frequency change on the DC transmission power, three ultra-high-voltage direct current (UHVDC) networks are selected to develop a coordinated optimization scheme. Constant current control is adopted on the rectifier side, constant voltage control is adopted on the inverter side, and FLC control is added.  
When the system's critical AC communication channel AC2 experiences an N\(-\)1 fault, the primary oscillation modes of the power grid under operating modes are as shown in Table 2. Assume that the maximum percentage \(\varepsilon\) of each DC that can participate in power modulation is 5%. When the system frequency changes, the DC modulation amount is automatically adjusted with the frequency deviation, FLC has an adjustment dead zone (FLC dead zone is set at 0.05 Hz in this simulation example), a certain DC modulation capability is retained, and \(\mu\) is set at 0.68. The multi-DC modulation coordination optimization strategy under two operating modes is simulated and verified, respectively.  
Figure 3: Coordination and optimization strategy of multiple DC modulation.
# Individuals Identification Based on Palm Vein Matching under a Parallel Environment
## 5 Results
### Comparison with State-of-the-Art Approaches
According to [69], the performance of two algorithms is significantly different if their corresponding ranks differ by at least the critical difference computed as:  
\[CD=q_{\alpha}\sqrt{\frac{k(k+1)}{6N}}=2.394\times\sqrt{\frac{7\times 8}{6}}=7.31, \tag{8}\]  
where \(q_{\alpha}\) is the critical value based on the Studentized range statistic, \(k\) is the number of algorithms to compare, and \(N\) is the number of datasets. Based on this criteria, the Bonferroni-Dunn test does not find any algorithm with significant differences from our approach. To contrast the above results, we provide the results of the [PERSON]'s step-down procedure in Table 11, which is more powerful than the Bonferroni-Dunn's and makes no additional assumptions about the hypotheses tested. The [PERSON]'s test at \(\alpha=0.05\) confirms previous results, finding that the proposed approach is slightly better than state-of-the-art methods on CASIA-MS-PalmprintV1 database, but it is not statistically superior. From the previous results, we can conclude that no significant differences are found respect to EER results, so our proposed method achieves comparable results in regards to state-of-the-art approaches on the evaluated dataset. Hence, further analysis on many more databases should be performed in order to provide a wider comparison against state-of-the-art. However, the results provide evidence that the deformation-based approach, which we introduce in our method, is suitable for palm vein recognition \begin{table}
\begin{tabular}{c c c} \hline \hline
**Approach** & **EER** & **Ranking** \\ \hline [PERSON] et al. [38] & 0.00996 & 3.0 \\ [PERSON] and [PERSON] [28] & 0.0236 & 5.0 \\ [PERSON] et al. [41] & 0.0073 & 2.0 \\ [PERSON] [34] & 0.0133 & 4.0 \\ [PERSON] et al. [29] & 0.03 & 6.0 \\ [PERSON] et al. [68] & 0.1170 & 7.0 \\ Proposed method & 0.0072 & 1.0 \\ \hline \hline \end{tabular}
\end{table} 
Table 10: Rankings of different approaches based on EER results on CASIA-MS-PalmprintV1 database. and also improve the time efficiency of the baseline with a significant speed-up above \(15\times\). These results demonstrate that our proposal by combining a sparse matching algorithm under a multi-core platform can be an effective alternative for deformation-based palm vein recognition, whilst obtaining state-of-the-art results with a low computational cost.
# Finite Element Analysis of Geogrid-Incorporated Flexible Pavement with Soft Subgrade
## 2 Research Approach and Numerical Simulation
### Mesh and Boundary  
An 8-noded hexahedral brick element (C3D8R) is employed to divide the entire pavement prototype into smaller elements. Triangular prism elements (C3D6) are used to mesh the geogrid. Various mesh biases are investigated, with a finer mesh near the loading area and a coarser one elsewhere. Mesh refinement is also explored, with Figure 2 depicting  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Layers**} & \multirow{2}{*}{\begin{tabular}{c} **E** \\ **(MPa)** \\ \end{tabular} } & \multirow{2}{*}{\
\begin{tabular}{c} **\(\mu\)** \\ \end{tabular} } & \multirow{2}{*}{
\begin{tabular}{c} **(kg/m\({}^{3}\))** \\ \end{tabular} } & \multicolumn{2}{c}{**C**} & \multicolumn{2}{c}{**\(\boldsymbol{\varTheta}\)**} & \multirow{2}{*}{**Element Type**} & \multirow{2}{*}{**Failure Criterion**} \\ \cline{1-1} \cline{5-8}  & & & & & & & \\ \hline Asphalt Concrete & 5400 & 0.4 & 2400 & - & - & C3D8R and C3D6 & LE \\ Binder Course & 5400 & 0.4 & 2500 & - & - & C3D8R & LE \\ Base Course & 1200 & 0.35 & 2200 & 10 & 40 & C3D8R & M-C \\ Sub-base Course & 1000 & 0.35 & 1800 & 10 & 40 & C3D8R & M-C \\ Subgrade & Variable & 0.35 & 1600 & 10 & 30 & C3D8R & M-C \\ Embankment & 400 & 0.3 & 1500 & 10 & 30 & C3D8R & M-C \\ Geogrid & 629.3 & 0.3 & 1100 & - & - & C3D6 & LE \\ \hline \hline \end{tabular} Note: C3D8R = 8-noded hexahedral brick, C3D6 = 6-noded triangular prism, LE = linear elastic, M-C = Mohr-Coulomb failure criterion, E = elastic modulus, \(\mu\) = Poisson’s ratio, and \(\varTheta\) = angle of internal friction.  
\end{table}
Table 1: Properties of the pavement layers and geogrid used in the FE model.  
Figure 1: Overview of the pavement and geogrid.  
the selected meshes for this model. Regarding boundary conditions, the bottom of the pavement is completely fixed, prohibiting any translation or rotation of its bottom nodes. The sides of the model are also restricted from certain translations and rotations along specific axes, as illustrated in Figure 2. A frictional behaviour is developed between two layers using the'surface-to-surface' contact behaviour. A hard contact surface is selected with a friction coefficient of 0.3.
# Metal Recovery from Wastes: A Review of Recent Advances in the Use of Bioelectrochemical Systems
## 2 Bioelectrochemical Systems for Metal Recovery
The pH of the medium is another factor that exerts a determining influence on the performance of the MFC. Studies have demonstrated that the behavior of the MFC varies depending on the pH level. Typically, higher anodic pH levels result in lower yields due to the reduced number of protons migrating to the cathode. Neutral anodic pH levels tend to favor the growth of biofilms. However, for cathodic metal recovery, a lower pH is typically required to prevent the precipitation of metals in the form of hydroxides and enhance cell performance by increasing the availability of protons that can be transported [10; 64; 67; 68; 69]. Overall, the literature review presented in Table 2 underscores significant progress and persistent challenges in applying BES for metal recovery. Integrating BES with complementary technologies, such as microbial electrodialysis and photo-assisted processes, has improved recovery rates and operational efficiency, while advancements in carbon-based and functionalized electrode materials have enhanced conductivity, biofilm formation, leading to improved power output, process rates, and selectivity for metals like copper, nickel, and zinc. Multi-chamber and stacked designs now enable simultaneous metal recovery, desalination, and pollutant degradation, showcasing the versatility of BESs.
## 3 Controller Design
### Speed Loop Controller Design
\tag{9}\]  
In order to design the sliding mode control law for Equation (8), here, we define an integral sliding surface as:  
\[s=x_{1}+c\int\limits_{0}^{t}x_{1}dt \tag{10}\]  
where \(c\) is the integral gain (\(c>0\)). The reaching law is chosen as:  
\[\dot{s}=-\varepsilon sign(s)-ks \tag{11}\]  
where \(\varepsilon\), \(k\) are positive real numbers, \(sign()\) is symbolic function. Substituting the estimated lumped disturbance \(z_{2}\) into Equation (5) yields the derivative of \(s\) as:  
\[ \begin{array}{ll}\dot{s}&=\dot{x}_{1}+cx_{1}\\ &=z_{2}+bi_{q}^{*}+cx_{1}=-\varepsilon\text{sgn}(s)-ks\end{array}  \tag{12}\]  
and an ESO-based sliding mode controller can be designed as:  
\[i_{q}^{*}=\frac{-cx_{1}-\varepsilon\text{sgn}(s)-ks-z_{2}}{b} \tag{13}\]  
Defining a Lyapunov function is as:  
\[V=\frac{1}{2}s^{2} \tag{14}\]  
To differential \(V\) yields:  
\[ \begin{array}{ll}\dot{V}&=s\dot{s}=s(R+b_{q}^{*}+cx_{1})\\ &=s(R-cx_{1}-\varepsilon sign(s)-ks-z_{2}+cx_{1})\\ &=s(R-z_{2})-\varepsilon|s|-ks^{2}\end{array}  \tag{15}\]  
here we quote a conclusion in [34], if the gain of ESO (11) is large enough, then the observer error \((R-z_{2})=\left|\frac{\alpha_{1}}{\alpha_{2}}w_{0}\right|\to 0\), \(w_{0}\) is the derivative of lumped disturbance. From Equation (17)  
\[\dot{V}=-\varepsilon|s|-ks^{2}\leq 0 \tag{16}\]  
When the sliding mode motion occurs on sliding surface \(s=0\), we can derive  
\[s=0\rightarrow\dot{s}=\dot{x}_{1}+cx_{1}=0 \tag{17}\]  
If \(c>0\), the existence condition of sliding mode and exponential convergence of \(x_{1}\) can be guaranteed.
# Power Management for Connected EVs Using a Fuzzy Logic Controller and Artificial Neural Network
## 4 Simulation Result and Analysis  
Simulations of the proposed hierarchical power management for a connected EV are presented in this section. This section has three parts: simulation parameters and setup, power demand prediction results, and HESS power distribution results. The simulation is performed in MATLAB/Simulink R2020a for 300 s of simulation time duration. This simulation aims to test the accuracy of power demand prediction and test the proposed power management strategy's ability to distribute power between the battery and SC.
# Numerical and Experimental Investigation of Recycled Brick Coarse Aggregate Concrete
## 3 Results and Discussion
### Calibration of the Numerical Model  
#### 3.4.1 Stress-Strain Relationship  
Figure 10 shows the finite element model of RBCA concrete, with the green circle representing RBCA and the dark green circle representing NCA. The mechanical parameters were used to conduct a two-dimensional mesoscopic numerical simulation, as shown in Table 3. Figure 11 shows the calculated stress-strain curves of RB-0, RB-50, and RB-100, respectively. Compared with the experimental values of RB-0, RB-50, and RB-100, the errors of the calculated peak strength were 4.2%, 5.0%, and 6.1%. Similarly, the errors of the peak strain were 4.5%, 3.8%, and 4.3%, and the errors of the elastic modulus were 10.5%, 10.3%, and 11.4%, respectively. It can be seen that the numerical simulation results are relatively consistent with the experimental stress-strain relationship. However, the compressive strength, peak strain, and elastic modulus are slightly higher than the simulation values. All these observations can be attributed to the lower strength of red brick is compared to that of the mortar matrix and to the uniaxial compressive strength of RBCA concrete being between the strength of the mortar matrix and red brick. Therefore, both the mesoscopic method's feasibility and the rationality of parameter selection are preliminarily verified.
## 4 Security and Performance Analysis
### Security Analysis
#### 4.1.5 Security against Node Capture Attacks  
When security is needed to transmit data between the cluster node and the sensor node or between the cluster node and the base station node, we use the keys \(K_{si}\) and \(K_{ci}\), respectively, for encryption. We make use of the one-way hash function to generate the key because the one-way hash function can prevent an attacker from inverting the key. (1) \(h(x)\) is relatively easy to compute for any given \(x\), making both hardware and software implementations practical. (2) For any given value \(y\), it is computationally infeasible to find x such that \(h(x)=y\). This is sometimes referred to in the literature as the one-way property. (3) For any given block x, it is computationally infeasible to find \(z\) not equal to \(x\) with \(h(z)=h(x)\). This is sometimes referred to as weak collision resistance. A comparison of the security and characteristics of the grid-based schemes is given in Table 2.  
(1) Because TTDD, CODE and DARQ do not support dynamic session-key management, they may be susceptible to various attacks.  
(2) In CODE and TTDD, the base stations have to reissue a query to request data or use local flooding to request data when they move out of the original grid. This will increase energy consumption and the number of collisions. DARQ and our scheme will limit the interest region to prevent a flooding storm.  
(3) If the base station moves out of the original grid, it reconstructs a new routing path. But CODE does not solve the routing problem when there are obstacles or voids in a sensor field.