esa-sceva/satcom-chunk-collection huggingface dataset:
## 2 Materials and Methods
### Estimation of Impact Force  
A piezoelectric force sensor was used to estimate the impact forces at the surface during treatments. To measure the reaction forces at the surface; an alternative fixture was developed to house the sensor and impact plates. This fixture contains linear ball bearings instead of steel bushings to guide the plate, as seen in Figure 7a. The support rods were thickened, and the four previous compression springs were replaced with two larger springs. Proper calibration using a strain gauge was performed so that the correct amount of static force could be determined based on the compression of the spring system. The sensor was attached to the moving plate on the fixture with a titanium specimen used as an impact cap. Operation of the UIT during the estimation of impact force was controlled in much of the same way as during the UIT. The sensor would register the forces from the UIT impacts on the titanium cap. For simplistic design, the cap was a repurposed fatigue specimen.  
Due to the design of a repurposed fatigue specimen as an impact surface, reaction forces can be registered by the sensor depending on its distance from the impact. The titanium cap was treated as a double supported beam with one end constrained by a bolt and the other end constrained by the sensor using a double-sided thread. The double supported beam assumption allows for a simple ratio to be developed based equilibrium of moments to solve for the actual impact forces. A diagram of the impact set up can be seen in Figure 7b,c The selected distances between the sensor and the impact region are displayed in Figure 7d, where \(d_{1}\) is 8.89 mm and \(d_{2}\) is 47.752 mm. The relationship between the sensor reaction force and the impact force is presented in Equation (1).  
\[F_{impact}=-F_{Sensor}\frac{d_{2}}{d_{1}}, \tag{1}\]  
Figure 7: Experimental setup for impact force estimation. (**a–c**) Impact force fixture; (**d**) impact areas and distances.  
where F\({}_{\text{impact}}\) is the force of impact and F\({}_{\text{sensor}}\) is the force registered by the sensor.  
Data acquisition was performed using a Lecroy WaveSurfer 3000 Oscilloscope [80]. The force sensor was a PCB piezoelectric force sensor model 208C05. The force range of the sensor was 0 to 4500 kgf. The conversion from voltage to force was assumed to be linear with a sensitivity of 0.2170 mV/N (\(\pm\)15%).  
Calibration of the sensor was checked using test procedure AT501-5. The amplifier gain of the sensor was set to 100. Additional shrink tubing was added between the sensor and the wire nuts to prevent vibrations during testing from unscrewing and ejecting the wires from the sensor. The peak voltage read by the sensor for a short ultrasonic impulse was regarded as the impact force for a given static load. The compression of the springs drives the static load with the total stiffness of the system equal to 3.06 N/mm.
# A Novel Crowdsourcing-Assisted 5G Wireless Signal Ranging Technique in MEC Architecture
## 2 Background and Related Work
### Wireless Signal Ranging Technology
#### 2.1.1 Base Station-Assisted Signal Ranging
A recent study combined RSS and AOA to enhance localization in non-line-of-sight (NLOS) environments [13], demonstrating that integrating complementary modalities improves resilience to multipath and shadowing effects.
# Three-Band Spectral Camera Structure Design Based on the Topology Optimization Method
## 2 Design of Three-Band Structural Components  
### Structural Design Requirements  
The three-band multispectral camera operates across three spectral ranges: visible light (450-900 nm), mid-wave infrared (3.8-4.8 \(\upmu\)m), and long-wave infrared (8-12 \(\upmu\)m). To meet the high requirements for assembly accuracy and mechanical stability across these spectral bands, the structural design must ensure that the first-order natural frequency exceeds 100 Hz. During the design process, structural stability and assembly precision must be maintained. To achieve this, the three-band structure is divided into several independent units, adopting a modular design approach that allows each unit to be independently assembled and tested. Once testing is completed, the components are integrated and adjusted as a whole.  
To achieve a compact and efficient overall structure for the spectral camera, the optical design employs a common-aperture scheme, integrating imaging technologies for visible light, mid-wave infrared, and long-wave infrared. The optical system is based on an R-C coaxial catadioptric optical design, characterized by a large relative aperture, high throughput, and a shared field of view. As shown in Figure 1, the spectral camera system consists of five optical components: the primary and secondary mirrors, the beam-splitting section, the visible light section, the mid-wave infrared section, and the long-wave infrared section. Light first enters the primary mirror and is reflected onto the secondary mirror. The light is then reflected by the secondary mirror onto the beam-splitting component, which directs the beams separately to the visible light system, the mid-wave infrared optical system, and the long-wave infrared optical system, where the final imaging occurs on the detectors.
# Chin Morphology in Relation to the Skeletal Pattern, Age, Gender, and Ethnicity
## 2 Materials and Methods
### Measurements  
CBCT images of Korean patients were acquired using a CBCT system (Zenith3D, Vatech Co., Seoul, Korea). CBCT images of Egyptian patients were acquired using a CBCT system (Soredex SCANORA 3D, Nahkeatine 16, Tuusula, Finland). CBCT data were stored in Digital Imaging and Communications in Medicine (DICOM) format. Data analysis was performed by a single operator. All DICOM data were imported into Invivo(tm) 6 (Anatomage, San Jose, CA, USA) for further processing and analysis. Landmarks and reference planes for analysis were defined after consulting previous studies [24]. The Frankfort horizontal plane was defined as the plane that intersects both portions and the left orbitale, and the mandibular plane was defined as the plane formed by connecting the gonion and menton on both sides (Figure 1). The chin was defined as a plane descending through point B, parallel to the left and right gonions, perpendicular to the mandibular submarginal plane, and anterior to that plane (Figure 2). The mandible segmentation with facial midsagittal plane was defined as a plane perpendicular to the Frankfort horizontal plane through the nasion and sera. The longest vertical distance that the excised chin faced in the midsagittal plane was defined as the chin height, the longest horizontal distance was defined as the chin width, and the difference between the distance from the gonion to pogonion and the distance from the gonion to point B (average of the left and right sides) was defined as the chin depth. Chin volume was measured using the Invivo(tm) 6 imaging software. Using the pre-defined values in the software, the threshold values for \"bone\" were set. The chin region was then removed from the 3D model of the mandible from the DICOM picture series using the cropping tool, and the volume was determined using the automatic measurement function (Figure 3). Aluminum bars were used to confirm that the difference in CBCT systems did not affect the measured values since CBCT image data obtained from two different CBCT systems were used in this study, as shown in a previous study [25]. Thirty CBCT pictures were randomly selected and measured using [PERSON]'s formula at intervals of two weeks under identical circumstances [26] to analyze the potential operator error. Anteriorposterior skeletal patterns were classified into three groups based on the ANB angle: Class I (\(-1^{\circ}\) < ANB < 4\({}^{\circ}\)), Class II (ANB \(\geq\) 4\({}^{\circ}\)), and Class III (ANB \(\leq\) \(-1^{\circ}\)). Vertical skeletal patterns were classified into three groups based on the mandibular plane angle (MP): hypodivergent (MP \(\leq\) 23\({}^{\circ}\)), normodivergent (23\({}^{\circ}\) < MP < 30\({}^{\circ}\)), and hyperdivergent (MP \(\geq\) 30\({}^{\circ}\)). The demographics of the patient's skeletal pattern are shown in Table 1.  
Figure 1: (**a**) The Frankfort horizontal plane. (**b**) The mandibular plane.  
Figure 3: (a) Cutout of chin by clipping. (b) Chin used for measurement.  
Figure 2: Definition of chin.
# Compact UHF Circularly Polarized Multi-Band Quadrifilar Antenna for CubeSat
## 5 Discussion  
The proposed structure was validated in space, and the non-deployable passive antenna was demonstrated to be able to cover multiple bands in the UHF frequency with a 3U CubeSat configuration. It should be noted that the antenna's performance could be further enhanced using a lower-loss substrate. Due to the limited development time, we selected the FR-4 material to benefit from the space qualification and reduced production time. From a 3D electromagnetic solver simulation with a Rogers 4350b substrate (tan \(\delta\) = 0.002), an average gain enhancement of about 1.5 dB is estimated. This study highlights the strong impact of the satellite structure on compact antenna performance. It was clearly shown that for both input impedance and gain, the CubeSat chassis modifies the distribution of the currents and thus changes the reflection coefficient and radiation pattern. The grounding of the proposed antenna with the CubeSat metal structure plays a crucial role in the antenna performance and should not be underestimated. The use of a characteristic mode analysis in the preliminary design phase of the structure would enable more comprehensive modeling and would reduce the integration risk. In comparison with the state of the art presented in Table 1, the proposed antenna offers a more compact form factor, which enables integration into a 1U cubesat face. The strong miniaturization of the antenna structure limits the operating frequency fractional bandwidth to 7.8%, which  
Figure 14: Final integration of the antenna within the 3U LS3 satellite with the proposed antenna on the front.  
Figure 15: (**a**) Received strength indicator on the terrestrial node versus elevation. (**b**) Position of the satellite when LoRa packets are received in the Antibes area (gray marker).  
is sufficient for the targeted application. In the future, multi-band operations, including 400 MHz, L-band, and S-band, will also be considered.
# Improved Direct Linear Transformation for Parameter Decoupling in Camera Calibration
###### Abstract  
For camera calibration based on direct linear transformation (DLT), the camera's intrinsic and extrinsic parameters are simultaneously calibrated, which may cause coupling errors in the parameters and affect the calibration parameter accuracy. In this paper, we propose an improved direct linear transformation (IDLT) algorithm for calibration parameter decoupling. This algorithm uses a linear relationship of calibration parameter errors and obtains calibration parameters by moving a three-dimensional template. Simulation experiments were conducted to compare the calibration accuracy of DLT and IDLT algorithms with image noise and distortion. The results show that the IDLT algorithm calibration parameters achieve higher accuracy because the algorithm removes the coupling errors.  
camera calibration; direct linear transformation; parameter decoupling +
Footnote †: journal:
# An Approach for Pronunciation Classification of Classical Arabic Phonemes Using Deep Learning
### Arabic Phonemes and Their Pronunciation  
A phoneme is the smallest unit of sound in human speech [3]. Phonemes include all the distinct units of sound spoken in a language. The Arabic language consists of 34 phonemes that can be broken down into 28 consonants, three short, and three long vowels [4] known by their common names of Fatha, Damma, and Khasra. Pronunciation is a general term that includes several distinct features present in human languages. The correct pronunciation is hard and challenging to measure because there is no universal definition for correctness in the context of human languages, but there has been some research in this domain [5,6].  
In the Arabic language, the accurate pronunciation of phonemes is required in learning the language to void change in the meaning of the sentence. In many countries around the world, the CA is part of the schools' syllabus. Correct pronunciation of phonemes as per defined rules is an essential requirement to preserve the meaning of the words [7,8]. Mispronunciation results in two types of errors; firstly, it changes the meaning of the word completely. Secondly, it defies the rules of pronunciation, and both errors are forbidden in CA. Learning the correct pronunciation of Arabic alphabets is challenging, and it requires each learner to follow an individual teacher, who listens and corrects the mistakes separately for each learner [9]. These corrections belong to the pronunciation of all the 84 variations of phonemes. A major distinction of the CA from MSA is the emphasis on the correct use of vowels. When speaking CA, the speakers tend to produce all the sounds according to the existing rules for CA pronunciation. CA has precise and explicitly defined rules for correct pronunciation to conserve the accurate meaning of the words and provides a framework to facilitate both the natives and non-natives learning the language [10]. These rules are standardized, widely available, and recognized by the Arabic speaking world [11]. In CA, alphabets' articulation points and characteristics and massive practicing of vocals play a significant role in correct pronunciation. On the contrary, it has been studied previously that in the case of MSA, the different dialects such as Saudi, Egyptian, and Sudanese have different qualities of vowel pronunciation [12].
# Early Ventricular Fibrillation Prediction Based on Topological Data Analysis of ECG Signal
## 2 Materials and Methods
### TDA Features Extraction
#### 2.2.1 Phase Space Reconstruction
With the increase of \(m\), if the embedding changes the distance between the neighbors appreciably, they are regarded as false neighbors. Figure 3 illustrates the phase space trajectories of a 10 s VF split frame and a 10 s nVF split frame when \(m\) is chosen as 2 and \(\tau\) is chosen as 12. As shown in Figure 3, PSR reconstructs attractors through finite data to observe the behavior of the dynamic system. For the nVF split frame in Figure 3b, the curves in the phase space image show a regular structure with a compact distribution of trajectories. For the VF split frame in Figure 3a, the curves fill the region in an irregular manner, which is caused by the abnormal heart rhythm, resulting in an obvious difference between the phase space trajectories of VF and nVF. PSR effectively distinguishes between VF and nVF split frames, whose structures can be statistically characterized by TDA. Figure 3: Phase space trajectories of VF and nVF split frames. (**a**) VF split frame; (**b**) nVF split frame.
# Shear Tests of Deep Hollow Core Slabs Strengthened by Core-Filling
## 4 Review of the Code Provisions and Recommendation
### Comparison of Shear Strengths by Testing and the Code Equations  
Table 5 compares the shear strengths of the test specimens (\(V_{n,test}\)) and those calculated using the design codes (\(V_{n,code}\)). The ACI 318-14 code provided conservative evaluations of shear strengths for specimens other than the HR 2/4 specimen due to the additional strength reduction factor (0.5) provision applied to PHCS with thickness greater than 315 mm. When the additional strength reduction factor was not applied, as in the ACI 318-05 provision, the ACI code equation evaluated the shear strengths of the NR-0/4 and NR-2/4 specimens very accurately, while it showed a tendency to considerably overestimate the shear strengths of the NR-4/4, LR-2/4, and HR-2/4 specimens.  
The CSA-A23.3 code provided conservative evaluations on the shear strengths of the NR-0/4 and NR-2/4 specimens, and estimated the shear strengths of the remaining specimens to be on the unsafe side. The BS EN 1168 code also provided the shear strength estimation results on the unsafe side for all specimens. In particular, all structural design codes, except for ACI 318-14, provided the shear strength estimation results on the unsafe side with respect to the NR-4/4 specimen in which all hollow cores were strengthened by in-filled concrete, and LR-2/4 and HR-2/4 specimens with helix shear reinforcements. As can be identified from the test results reported earlier, the reasons are that the increase in shear strength was clearly observed in the NR-2/4 specimen with two filled cores compared to the NR-0/4 specimen, whereas that measured in the NR-4/4 specimen with four filled cores was smaller than the NR-2/4 specimen, because the web of the PHCS unit at the edge of the section was separated from the filled core before reaching the ultimate load. A further reason is that the helix shear reinforcement placed in the filled cores failed to exert effective shear resistance. Therefore, a close examination of the code equations is needed to estimate the shear strengths of PHCS with filled cores safely and accurately using the design codes.
# Defect Detection in Striped Images Using a One-Dimensional Median Filter
## 2 Materials and Methods
### Flow of Defect Detection
#### 2.3.1 Pre-Processing and Image Rotation  
The pre-processing flow is shown in Figure 4. First, a Gaussian filter is used to smooth the image, and histogram equalization is used to reduce the uneven brightness. Then, Gamma correction is used to enhance the contrast. Finally, binarization and image complement are performed to make the blocks foreground. Using the vertices of the middle block of the processed image, we can determine the rotation angle, and the stripes in the image can be rotated to the horizontal to facilitate the subsequent median filtering.
## 2 Materials and Methods
### Quality Control  
Extensive quality-control measures were used in-house and in the field to ensure that the laboratory and field protocols were not causing false positives or negatives in the corresponding environmental results. Materials needed to conduct one field blank were included in each sample kit which included 25 mL of LCMS-grade water, a syringe filter, syringe and two 15-mL glass vials. The procedure for collection, storage and shipment of this QC sample was exactly the same as for environmental samples, except using LCMS-grade water. This step enables an evaluation of sample contamination derived from collection in the field.  
In addition to field QC measures, a blank as well as method and instrumental QCs were injected after every 10 injections during analytical runs. The laboratory blanks were pure LCMS-grade water with all internal standards spiked to a concentration of 400 ng/L. Both method and instrumental QCs consisted of all target APIs spiked in LCMS-grade water at a concentration of 80 ng/L with all QCs at 400 ng/L. However, the method QC underwent the same sample storage and preparation measures as actual samples and the instrumental QC was spiked directly into a HPLC vial prior to analysis. Before each use, the nebuliser and spray guard of the mass spectrometer were cleaned with methanol. Additionally, prior to an analytical run, the chromatography column was equilibrated with 20 injections of a composite environmental sample (made from equal aliquots of the samples being analysed in respective runs) in order to condition the chromatography column prior to analysis.
# Resonance-Driven Passive Folding/Unfolding Flapping Wing Actuator
## 2 Structure and Modelling  
### Structure of the Flapping-Wing Actuator  
Figure 1a shows photographs of the flapping-wing actuator investigated in this study. This structure is based on our previously reported flapping-wing robot [10]. It is composed of a trapezoidal unimorph piezoelectric actuator and a biomimetic wing. The piezoelectric actuator consists of a 100-\(\upmu\)m-thick piezoelectric Pb(In\({}_{1/2}\)Nb\({}_{1/2}\))O\({}_{3}\)-Pb(Mg\({}_{1/3}\)Nb\({}_{2/3}\))O\({}_{3}\)-PbTiO\({}_{3}\) (PIN-PMN-PT) plate and a 130-\(\upmu\)m-thick Ti plate. The PIN-PMN-PT plate was manufactured by TRS Technologies, Inc. (State College, PA, USA). The wing consists of a carbon fiber reinforcing plastic (CFRP) leading-edge rod, Ti/polyimide composite veins, and a polyester membrane; these are laminated by hot pressing. The mass of the wing is 17.8 mg. The wing is fixed at the tip of the piezoelectric actuator and its wingspan extends obliquely downward. A spring, which is a key component for the folding/unfolding function, was placed between the piezoelectric actuator and wing. Figure 1a (right) shows the enlarged image of the leaf spring made up of a 100-\(\upmu\)m-thick polyether ether ketone sheet. The mass of the while device is 140 mg. Figure 1b illustrates the principle of the flapping actuation. When a voltage is applied to the piezoelectric material, a stress is induced in it by the piezoelectric effect. This stress bends the actuator, causing the wing to swing around the \(z\)-axis. By applying a cyclic voltage wave, the frequency of which matches the system resonance, a large stroke motion can be excited. As reported in [11; 12; 13], the flapping wing generates a lift force. Here, the stroke angle (the angle between the wingspan and \(x\)-axis around the \(z\)-axis) is defined as \(\phi\). Figure 1c illustrates the folding/unfolding behavior. The leaf spring enables the wing to rotate around the \(y\)-axis. In this paper, we defined the initial wing attitude (oblique to \(x\)-axis) as the folded state. In contrast, a state in which the wing is directed nearly along the \(x\)-axis is defined as the unfolded state. The angle between the wingspan and \(x\)-\(y\) plane is defined as \(\theta\). The folding/unfolding motion defined in this study is not accurately biomimetic; the wing itself does not deform but the wing root is folded. We consider this structure to have an advantage in terms of the clear understanding of the folding/unfolding behavior owing to its simple kinematics compared with a fully biomimetic morphing wing system. This structure does not use the active mechanism to fold/unfold the wing as stated in the above-mentioned section; instead, the wing will be passively folded/unfolded by forces, such as centrifugal and lift forces, due to the stroke motion.