esa-sceva/satcom-chunk-collection huggingface dataset:
Sensors_**2009**, \(9\), 2148-2161; doi:10.3390/s90302148  
Sensors  
ISSN 1424-8220  
www.mdpi.com/journal/sensors  
Article  
Automatic Exudate Detection from Non-dilated Diabetic Retinopathy Retinal Images Using Fuzzy C-means Clustering  
**[PERSON] 1,*, [PERSON] 1 and [PERSON] 2**  
1 Department of Information Technology, Sirindhorn International Institute of Technology,  
Thammasat University 131 Moo 5, Tiwanont Road, Bangkadi, Muang, Pathumthani 12000,  
Thailand; E-mails: [EMAIL_ADDRESS], [EMAIL_ADDRESS]  
2 Faculty of Computing, Information Systems and Mathematics, Kingston University Penrhyn Road,  
Kingston upon Thames, Surrey, KT1 2 EE, UK; E-mail: [EMAIL_ADDRESS]  
* Author to whom correspondence should be addressed; E-mails: [EMAIL_ADDRESS];  
[EMAIL_ADDRESS] Phone: +66-2501-3505 Ext. 2021, Fax: +66-2501-3524  
Received: 29 January 2009; in revised form: 19 March 2009 / Accepted: 20 March 2009 /  
Published: 24 March 2009  
**Abstract:** Exudates are the primary sign of Diabetic Retinopathy. Early detection can potentially reduce the risk of blindness. An automatic method to detect exudates from low-contrast digital images of retinopathy patients with non-dilated pupils using a Fuzzy C-Means (FCM) clustering is proposed. Contrast enhancement preprocessing is applied before four features, namely intensity, standard deviation on intensity, hue and a number of edge pixels, are extracted to supply as input parameters to coarse segmentation using FCM clustering method. The first result is then fine-tuned with morphological techniques. The detection results are validated by comparing with expert ophthalmologists' hand-drawn ground-truths. Sensitivity, specificity, positive predictive value (PPV), positive likelihood ratio (PLR) and accuracy are used to evaluate overall performance. It is found that the proposed method detects exudates successfully with sensitivity, specificity, PPV, PLR and accuracy of 87.28%, 99.24%, 42.77%, 224.26 and 99.11%, respectively.  
**Keywords:** Exudates, diabetic retinopathy, non-dilated retinal images, Fuzzy C-Means clustering.
## 6 Conclusions  
We have proposed a novel interferometer-based 2D DOA estimation method for signals with known waveforms and unknown amplitude in this paper. By introducing the known waveforms, the 2D DOA estimation performance of the proposed method outperforms conventional method without known waveforms. Under most circumstances, the proposed method achieves the same performance as the ML method and coincides with the corresponding CRB. More important, the proposed method is simple and computationally efficient, since the 2D DOA estimates of multiple sources are obtained through a set of closed-form solutions without loss of too much accuracy. Consequently, our method is a better choice for 2D DOA estimation with known waveforms for uncorrelated or moderately correlated signals in wireless communications, radar and sonar system. These conclusions have been verified by the simulation results.  
Figure 10: Scatter plot of 2D DOA estimates of the proposed method.  
Figure 9: RMSE of DOA estimation versus correlation coefficient from 0 to 0.9. (**a**) RMSE of the elevation angle, (**b**) RMSE of the azimuth angle.  
Moreover, our method does not perform well for medium- or strong-correlated signals. Some possible further works may consider addressing the above problem as well as evaluating of theoretical lower bound on RMSE of the proposed method and extending the interferometer-based method to other planar arrays, such as uniform rectangular array or L-shape array.  
Conceptualization, Z.H. and Q.W. ([PERSON]); methodology, Z.H., J.Z. and Q.W. ([PERSON]); software, Z.H.; validation, Z.H. and Q.W. ([PERSON]); writing--original draft preparation, Z.H.; writing--review and editing, Z.H., Q.W. ([PERSON]), J.Z. and Q.W. ([PERSON]). All authors have read and agreed to the published version of the manuscript.  
This research was supported in part by the National Natural Science Foundation of China (NSFC) under Grant 61771108, National Science and technology major project under Grant 2016 ZX03001022 and the Foundation of Sichuan Science and Technology Project under Grant 18 ZDYF0990.  
Not applicable.  
The data used to support the findings of this study are included within the article.  
The authors declare no conflict of interest.
# A Systematic Literature Review of Various Control Techniques for Active Seat Suspension Systems
## 2 Biodynamic Model of the Human Body  
To improve the ride comfort of the seated human being in a vehicle, the seating suspension system with seated human body must be modelled [17]. In the prevailing literature, most studies considered the mass on the seat as a rigid dummy mass which is assuredly incapable to provide accurate information about the dynamic behavior of human body parts under vibration road excitation [18]. Recently, several researchers have paid more attention to the development of a mathematical model of the human body as a biodynamic model, considering the seated human posture, rather than a rigid dummy mass to certify high precise system modelling [19; 20]. Some of system models have been built using field experimental data results [21].  
The biodynamic model can be divided into three classes: lumped models, finite element model and multibody human model. The lumped model is widely used since it considers the human body as spring and damper. It can be modelled as 1 degree of freedom (1 DOF), 2 DOF or 3 DOF. The finite element model is a powerful discretization technique which considers the human body as a model of finite degree of freedom where the human body model parameters are normally obtained experimentally through the human corpses [22; 23]. The multibody human model is more complicated scheme than the lumped model since it considers the human body as a complex model whose properties result from connecting the rigid bodies through a pin and a socket joint [24]. In this review paper, all the representative research papers presented the seat and vehicle suspension system as a lumped system model consisting of mass, spring and damper because it provides simple mathematical equations in both time and frequency domain.  
The lumped mass-spring-damper system model was used to represent the human body model. A seating suspension system model with the seated human body generally varies in terms of structure complexity represented by degree of freedom starting from 1 DOF into 15 DOF, which typically depends on the number of body lumped masses connected through the springs and dampers [25]. For simplicity, the majority of studies have considered the seat suspension system model with a seated driver body as 1 DOF as presented in Figure 1a, which is mainly composed of a single stiffness, mass and damper [26; 27; 28], while others have used 2 DOF to model the seat and human body suspension system as illustrated in Figure 1b. The 2 DOF system is widely used in the vibration field due to its simple structure and it can offer more information about the model dynamic parameters than the 1 DOF system [29]. Some studies have presented the human body system of neck, pelvis, head and torso as 4 DOF in addition to the 1 DOF seat structure as shown in Figure 1c. Therefore, the 4 DOF is the best representation of the seated human body among all the DOF models because it can provide the most accurate parameter estimation of the human body system model [30].
# Bayesian Optimization Based Efficient Layer Sharing for Incremental Learning
## 1 Introduction
Hence, in [14], they identify to determine how much of the initial convolutional layers in the base network for learning new classes having similar features as the classes in the base network. However, estimating optimal sharing layer configuration is a non-convex and non-differential problem, so it cannot be solved using the gradient descent algorithm or convex optimization method [5; 22; 23]. Therefore, this method should explore all possible sharing layer cases to find the optimal ones that meet quality specifications and approximate the existing network sharing capacity for the new task-specific sharing configuration via similarity score. Thus, it forces to high computation complexity [24]. To solve this limitation, the proposed method utilizes a Bayesian optimization technique (BayesOpt) to get the optimal number of sharing layer without considering all possible cases. The BayesOpt is a class of machine learning-based optimization algorithm, and there are several previous works that shows BayesOpt guarantees the global convergence in combinatorial optimization problem [25; 26]. Therefore, with a properly designed loss function, the proposed algorithm can find a global optimal sharing layer for layer sharing-based incremental learning. In summary, the contributions of the proposed method are as follows:  
* We firstly define the sharing layer ratio estimation problem for incremental learning as discrete combinatorial optimization problem with the global optimization strategy. * By utilizing BayesOpt, the proposed method effectively computes the global optimal sharing capacity of the existing network for accommodating the new task without computing all possible cases. * The proposed algorithm can adaptively find the global optimal sharing configuration with the target accuracy via adjusting the threshold accuracy parameter in the proposed loss function. To employ BayesOpt, the proposed objective function should be continuous. It is a discrete function due to the number of layers, designed to represent the continuous combinatorial optimization problem with a step function. The remainder of this paper is organized as follows. Section 2 gives the brief explanations of target incremental learning algorithm in [14]. Section 3 introduces our proposed algorithm focusing on both the proposed objective function and the utilization of BayesOpt. Section 4 shows the experimental results on the representative classification dataset. Finally, Section 5 summarizes the proposed algorithm. This work is an extension version of [27].
# Demonstrating the Potential of a Low-Cost Soil Moisture Sensor Network
## 2 Materials and Methods
### Reagents and Methods
#### 2.2.1 Intersensor Variability in Dielectric Standards  
To determine intersensor variability, 10 sensor units were tested in liquid media and air of known \(\varepsilon\). Sensors were fully immersed and allowed to collect 5 readings in each standard at 20 \(\pm\) 1 \({}^{\circ}\)C. Apart from acetic acid, for which only one measurement was collected, all measurement were collected in triplicate.
# Electochemically Engineered Mesoporous Sn-Oxide Rods for Anode Materials in Lithium-Ion Batteries
## 2 Experimental
### Fabrication and Electrochemical Tests of Electrodes and Cells  
To evaluate the electrochemical characteristics of the Sn and Sn-oxide rods fabricated in Section 2.1 as anode active materials for LIBs, non-anodized Sn rods and Sn rods anodized at 6 V, 8 V, and 10 V (core(Sn)-shell(SnO\({}_{\text{x}}\)) structures) were tested. Carbon black (acetylene, 50% compressed, Alfa Aesar, Ward Hill, MA, USA) and polyvinylidene fluoride (PVdF, M\({}_{\text{w}}\) \(\sim\) 534,000, Sigma-Aldrich, St. Louis, MO, USA) were used as the conductive additive and binder, respectively. These three components were mixed in a weight ratio of 7:2:1 and dispersed in \(N\)-methyl-2-pyrrolidinone (NMP, \(\geq\)99.0%, Sigma-Aldrich, USA) to prepare a slurry. The slurry was cast onto a copper foil (20 \(\upmu\)m, 99.8%, Alfa Aesar, USA) using a doctor blade and dried overnight in a 60 \({}^{\circ}\)C oven. The dried anode was slit to a 16 mm diameter disc, with an anode loading level of 0.85 \(\pm\) 0.2 mg/cm\({}^{2}\). The prepared anode was assembled into a CR2032 coin cell in a two-electrode half-cell configuration, using lithium foil as the counter electrode and a Celgard 2400 membrane as the separator. 1 M lithium hexafluorophosphate (LiFP\({}_{6}\)) in ethylene carbonate (EC)/ethyl methyl carbonate (EMC) (3/7 \(v\)/\(v\)) + fluoroethylene carbonate (FEC) 3 wt.% (Dongwha Electrolyte, Nonsan-si, Republic of Korea) was used as the electrolyte. All cell assembly was conducted in an Ar-filled glove box (O\({}_{2}\), H\({}_{2}\)O \(<\) 1 ppm; Glove Box, Mbraun-Unilab, Garching, Germany).  
Cyclic voltammetry (CV) was performed to analyze the electrochemical properties of the porous Sn-oxide using a scan rate of 1 mV/s in the voltage range of 0.01-3 V at 25 \({}^{\circ}\)C. The charge/discharge characteristics, cycle life, and high-rate performance of the prepared anodes were evaluated in constant current (CC) mode in the voltage range of 0.02-1.5 V. The charge/discharge characteristics were assessed at a current density of 50 mA/g for the initial three cycles. The cycle life was further evaluated at 100 mA/g, while the rate performance was analyzed at 100, 200, 400, and 800 mA/g. All the experiments were conducted using a multichannel potentiostat/galvanostat system (VMP3, Biologic Co., Seyssinet-Pariset, Grenoble, France).  
All the fabrication, characterization, and electrochemical measurements were conducted in an air-conditioned laboratory maintained at a nominal temperature of 25 \({}^{\circ}\)C. The ambient temperature was continuously monitored with a thermometer and remained stable throughout the experiments.
# Stabilization of Transverse Modes for a High Finesse Near-Unstable Cavity
## 6 Conclusions  
In summary, we successfully locked a high-fineness near-unstable FP cavity to a dye laser in TEM\({}_{00}\) mode by using the PDH stabilization technique. The FP cavity had a linewidth of 379 kHz. This technique linked the FP cavity to the laser cavity, and the frequency of the FP cavity was locked in not only the fundamental transverse mode but also the high-order transverse modes. Such cavity-locked high-order transverse modes are potentially useful in cavity-enhanced SPDC to generate specific transverse modes of single photon and enhance the photon down-conversion efficiency in a specific angle. The design of this plane-concave FP cavity can also increase the threshold of the OPO cavity, which is crucial for single-photon generation. Furthermore, the operating wavelength of our cavity (605.78 nm) is suitable for the EIT experiments in Pr\({}^{3+}\) doped Y\({}_{2}\)SiO\({}_{5}\) crystal, which can be used for single-photon storage and quantum repeater in Pr\({}^{3+}\) doped Y\({}_{2}\)SiO\({}_{5}\) crystal.  
[PERSON] supervised the project; [PERSON]. ([PERSON]) and [PERSON] ([PERSON]) performed the experiments; [PERSON]. ([PERSON]), [PERSON] ([PERSON]), [PERSON] and [PERSON] analyzed the data; [PERSON] and [PERSON]. ([PERSON]) wrote the paper; All authors contributed to the discussions and revisions of the paper.  
Figure 8: The error signals output from the FP cavity operating at the TEM\({}_{00}\) (blue curve), the TEM\({}_{01}\) (red curve), and the TEM\({}_{02}\) (green curve) modes, respectively.  
Figure 7: The intensity distributions of different transverse mode output from the locked FP cavity. (**a**) is the case with the TEM\({}_{00}\) mode, (**b**,**c**) denote the cases with the TEM\({}_{01}\) and TEM\({}_{02}\) modes, respectively.  
**Funding:** This work is financially supported by the National Natural Science Foundation of China (Grant Nos. 91750204, 61475077 and 11774182), the 111 project (B07013) and the Fundamental Research Funds for the Central Universities.  
**Conflicts of Interest:** The authors declare no conflict of interest.
###### Abstract
Image analysis in [20] is used to extract biomechanical features in swimming; this is a common practice for stroke correction, technique analysis, and as a visual aid for the athletes. Due to how different the conditions in the water are, this leads to problems such as blurred vision from the camera and bubbles from cavitation effects. Image analysis techniques are fundamental to enhancing clarity and overcoming this problem, and to automating the detection of limb segments related to important metrics. Fall prediction could use markers' positions [21] or bone maps estimations via a deep learning (DL) approach, composed of a convolutional neural network (CNN) with 97.1% accuracy [22]. In [23], an ANN predicted lower extremity joint torque based on ground reaction force (GRF) features, using the GRF and related parameters derived by the GRF during counter-movement jump (CMJ) and squat jump (SJ), calculating joint torque using inverse dynamics and an ANN. The following cost functions were used to track the model's performance through epochs: mean absolute error (MAE) [24], mean squared error (MSE) [25], and mean squared logarithmic error (MSLE) [26]. Based on a database of 28 regular runners, physical marker positions based on 32 anatomical and reflective markers, resulting in 96 tags, were sampled at 150 Hz. A model used these markers to predict three-dimensional forces (\(F_{x}\), \(F_{y}\), \(F_{z}\)) sampled at 300 Hz. However, due to differences between sampling frequencies, for each marker datum (source), two force data were given (target), making it impossible to merge both datasets and generate a prediction using a model. In this sense, two methods solved data granularity to fit a machine learning (ML) model, thereby matching both data streams and merging them into a single dataset, divided into down-sampled (force) and up-sampled (positions). In the sections of this report:
* We describe the methodology of the study: a description of the database and variables used (in the analysis), the architectures of the evaluated models, and their performance tests, in Section 2. * The results from the proposed analysis are shown in Section 3. * In-depth discussion going into aspects such as future work and limitations is in Section 4. * Finally, this paper concludes in Section 5 with the discoveries of this work.
# Optical OFDM for SiPM-Based Underwater Optical Wireless Communication Links
## 4 Optical OFDM Signaling  
O-OFDM is popular in indoor VLC systems and is proposed as a basis for evolving standards [21; 24]. DCO and ACO are among the most popular, while LACO is a recently proposed scheme [25] with a higher computational complexity and imposing more latency on the Rx side. Before focusing on these three, this section provides a brief presentation of the most important O-OFDM signaling schemes proposed in the literature so far.
# Motion Trajectory Prediction in Warehouse Management Systems: A Systematic Literature Review
## 2 Methodology
### Research Goal  
The aim of this literature review is to identify the latest solutions in the field of trajectory prediction. The methods presented in the review will be discussed in terms of their effectiveness, computational complexity, and applications in the context of employees' movement within the warehouse.
# Special Equipment Safety Supervision System Architecture Based on Blockchain Technology
## 5 Discussion
### The Feasibility of System Application and Promotion  
As for the application and promotion of the system in practical work, considering that many countries, including China, implement hierarchical supervision, it is recommended to first apply it in a small area (e.g., a city), and then gradually expand the scope of application. In this process, the formulation of regulations for the promotion, user training, and the iterative upgrade of the system also needs to be taken seriously.
# Influence of Isometric and Dynamic Fatiguing Protocols on Dynamic Strength Index
## 2 Materials and Methods
### Study Design and Procedures  
A repeated measure cross-over study design was used to explore the effects of two different fatiguing protocols (repeated CMJ and repeated IMTP) on DSI. Two separate visits for each fatiguing protocol were carried out at the same time of the day, at least 10 days apart. The order of the conditions (CMJ and IMTP protocols) between visits was randomized for each participant. The measurements were performed in a laboratory setting using a portable bilateral force platform (type 9260 AA, Kistler Instrumente, AG, Winterthur, Switzerland). Participants performed a general 10 min warm-up consisting of 6 min of alternating step-ups on a 25 cm high bench (80 beats per min) following arm, hip, knee and ankle mobility exercises (10 reps each), dynamic stretches of hip flexors, knee extensors and flexors (10 reps each) and bodyweight resistance exercises (heel raises, squats and crunches; 10 repetitions each). After the general warm-up, each subject performed 5 submaximal CMJs and IMTPs at 70, 80 and 90% of self-estimated maximal effort with 30 s of rest between each repetition, to familiarize themselves with the tasks. Before and after each fatiguing protocol, participants performed three bilateral CMJs with 30 s of rest between successive jumps and three maximal IMTPs with 30 s rest between repetitions to determine participants' maximal CMJ jump height and maximal produced force during IMTP. The order of the two tests was also randomized for each participant (the same order was followed by individual participants before and after the fatigue protocols). The recovery period between the fatigue protocols and subsequent testing was minimized, with \(\sim\)20 s elapsing between the cessation of the fatigue protocols and first repetition of subsequent testing. The total duration of CMJ and IMTP testing was \(\sim\)180-220 s, while the duration of the fatigue protocols was not pre-determined; rather, it was based on performance decline (see below).
# Development of Zirconium-Based Alloys with Low Elastic Modulus for Dental Implant Materials
## 4 Conclusions  
The Zr-7 Cu-xSn alloys were designed and manufactured for the first time to develop a new biomaterial with high strength, elasticity similar to human bone, and good corrosion resistance. This leads to the following conclusion.  
1. In the Zr-7 Cu-xSn alloys, Zr\({}_{2}\)Cu, an intermetallic compound was distributed along grain boundaries. As the Sn content increases, the Zr matrix decreases and the Zr\({}_{2}\)Cu phase coarsened to confirm solid solution strengthening.
2. The compression test was performed to obtain the stress-strain curves of the alloys. The compressive strength of the Zr-7 Cu-xSn alloy was in the range of 860-1200 MPa. The elastic modulus was obtained in the range of 14-18 GPa. It is possibly considered zirconium-based alloys are well suited as implant materials to neglect the stress-shielding effect.
3. A polarization test was conducted to measure the corrosion behavior of Zr-7 Cu-xSn alloys. The addition of Sn lowered the current density of Zr, and the average value of the current density of Zr-7 Cu-xSn alloy was about 0.0100 uA/cm\({}^{2}\). Therefore, it can be regarded as a biomaterial having good corrosion resistance.  
[PERSON], [PERSON], and [PERSON] carried out the experiments. [PERSON] wrote the manuscript with support from [PERSON] and [PERSON]. [PERSON] conceived the original idea and supervised the project.  
This research received no external funding.  
This research was supported by the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NO. 2017R1D1A3B03028681).  
The authors declare no conflict of interest.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Zr-7 Cu-xSn** & **1\%** & **5\%** & **10\%** & **15\%** \\ \hline \hline lcorr [μ/cm\({}^{2}\)] & 0.00065 & 0.0039 & 0.00090 & 0.0031 \\ Ecorr [mV] & \(-\)360.8 & \(-\)226.3 & \(-\)215.5 & \(-\)288.7 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Average value of current density and corrosion potential of Zr-7 Cu–xSn (x = 1, 5, 10, 15 wt%).  
Figure 5: Potential polarization curves of Zr-7 Cu–xSn (x = 1, 5, 10, 15 wt%).
# Research on Data Transmission of Laser Sensors for Reading Ruler
## 4 Sensor Technology and Code Reading Error Analysis
### Laser Ranging Sensor
Delay phase measurement and digital phase measurement are generally the most widely used methods. At present, the digital phase measurement principle is adopted for short-range laser rangefinders to obtain \(\phi\).