Miracle-dz/UniFAR-FTUs huggingface dataset:
Extracting Crop Spatial Distribution from Gaofen 2 Imagery Using a Convolutional Neural Network

Using satellite remote sensing has become a mainstream approach for extracting crop spatial distribution. Making edges finer is a challenge, while simultaneously extracting crop spatial distribution information from high-resolution remote sensing images using a convolutional neural network (CNN). Based on the characteristics of the crop area in the Gaofen 2 (GF-2) images, this paper proposes an improved CNN to extract fine crop areas. The CNN comprises a feature extractor and a classifier. The feature extractor employs a spectral feature extraction unit to generate spectral features, and five coding-decoding-pair units to generate five level features. A linear model is used to fuse features of different levels, and the fusion results are up-sampled to obtain a feature map consistent with the structure of the input image. This feature map is used by the classifier to perform pixel-by-pixel classification. In this study, the SegNet and RefineNet models and 21 GF-2 images of Feicheng County, Shandong Province, China, were chosen for comparison experiment. Our approach had an accuracy of 93.26%, which is higher than those of the existing SegNet (78.12%) and RefineNet (86.54%) models. This demonstrates the superiority of the proposed method in extracting crop spatial distribution information from GF-2 remote sensing images.
AN INVESTIGATION OF THE ERGONOMICS OF JEANS

Bu calismanin amaci kot pantolonun ergonomisini incelemektir. Calismada kot pantolonun ergonomisini incelemek, kot pantolon kullananlarin karsilastiklari problemleri belirlemek ve belirlenen problemlere gore kot pantolon kaliplarinin ergonomisine yonelik tasarimlar onermek icin bir anket formu hazirlanmistir. Anket 1170 universite ogrencisine uygulanmistir. Ogrencilerin 614’u kiz ve 556’si erkek, boylari 160cm ve alti ile 181cm ve ustu arasinda, kilolari 50kg ve alti ile 76kg ve ustu arasinda, 430’u dusuk bel, 705’i normal bel ve 35’i yuksek bel kot pantolon tercih etmislerdir. Elde edilen verilere ilaveten anket dort faktorde toplanmistir: “sikistirma rahatsizligi” (Faktor 1), “merdivenden cikma rahatsizligi” (Faktor 2), “gerilme rahatsizligi” (Faktor 3) ve “arkadan bel acilma rahatsizligi” (Faktor 4). Faktor analizi sonuclarinda; kadinlarin, 170cm ve altinda boya sahip olanlarin, 60kg ve altinda kiloya sahip olanlarin ve dusuk bel kot pantolon tercih edenlerin arkadan bel acilma rahatsizligini (Faktor 4), 66-70kg ile 76kg ve ustu kiloya sahip olanlarin sikistirma rahatsizligini (Faktor 1), ve yuksek bel kot pantolon tercih edenlerin sikistirma rahatsizligini (Faktor 1), merdivenden cikma rahatsizligini (Faktor 2) ve gerilme rahatsizligini (Faktor 3) yasadiklari gozlenmistir. Bu sonuclar acikca cogu kot pantolonun bel kisminda gercekten bir problem oldugunu gostermistir. Sonuc olarak, tespit edilen problemleri cozmek ve daha ergonomik kot pantolon uretmek icin kot pantolon kaliplarina yonelik bazi oneriler yapilmistir
Frequency-Domain Electrothermal Impedance Spectroscopy of an Actively Switching Power Semiconductor Converter

This paper develops impedance spectroscopy for characterizing transient heat transfer in assembled power semiconductor converter systems. The method addresses limits associated with traditional methods, for e.g., data sheet transient thermal impedance curves are step responses that only characterize the junction-to-case spatial-domain segment. The presented method utilizes an actively switching semiconductor as a controlled modulator of dynamic loss (heat) injections, along with multiple temperature measurements, to form spatial electrothermal impedance frequency response function (FRF) models. Complementary investigations of numerical and analytical modeling methods yield a general, compact thermal model template, for interpreting measured FRFs. A pulsewidth modulated power converter with integrated die and heat sink temperature sensing was characterized with the spectroscopy method. Obtained ambient-referred and relative FRFs describe transient heat transfer, including fast (die-level) and slow (sink-level) modes, over frequency decades with coherence. The FRFs were parameterized and interpreted using the derived compact thermal model.
A Novel Parallel Hybrid Excited Machine With Enhanced Flux Regulation Capability

A novel parallel hybrid excited (HE) machine with wide flux regulation range is proposed in this paper. The flux paths of permanent magnet (PM) and field winding are separated to avoid irreversible demagnetization and achieve improved flux regulation capability. Since the field winding and armature winding are located in the same stator slots, open-winding drive circuit can be employed to feed biased ac excitation in one set of winding and solve the spatial confliction of conventional hybrid excited machine. Finite element (FE) method is utilized to analyze the electromagnetic performances of the proposed HE machine, in comparison with the original HE machine. It is revealed that the proposed HE machine exhibits lower PM excited back-electromotive force (EMF), which is beneficial to high speed fault tolerant operation. Besides, the torque density can be higher with flux enhancing, albeit with reduced PM usage. Finally, a prototype is manufactured and tested to validate the FE predictions.
Evaluation of Interconnection Configuration Schemes for PV Modules with Switched-Inductor Converters under Partial Shading Conditions

Partial shading on photovoltaic (PV) arrays reduces the overall output power and causes multiple maximas on the output power characteristics. Due to the introduction of multiple maximas, mismatch power losses become apparent among multiple PV modules. These mismatch power losses are not only a function of shading characteristics, but also depend on the placement and interconnection patterns of the shaded modules within the array. This research work is aimed to assess the performance of 4 × 4 PV array under different shading conditions. The desired objective is to attain the maximum output power from PV modules at different possible shading patterns by using power electronic-based differential power processing (DPP) techniques. Various PV array interconnection configurations, including the series-parallel (SP), total-cross-tied (TCT), bridge-linked (BL), and center-cross-tied (CCT) are considered under the designed shading patterns. A comparative performance analysis is carried out by analyzing the output power from the DPP-based architecture and the traditional Schottky diode-based architecture. Simulation results show the gain in the output power by using the DPP-based architecture in comparison to the traditional bypassing diode method.
A systematic literature review of software effort prediction using machine learning methods

Machine learning (ML) techniques have been widely investigated for building prediction models, able to estimate software development effort as well as to improve the accuracy of other estimation techniques. The objective of this paper is to systematically review the recent studies which used and discussed the software effort estimation models built using ML techniques. The performed literature review is based on the empirical studies published in the time period of January 1991 to December 2017, by employing widely used guidelines. The review has selected a total of 75 primary studies after the careful filtering of inclusion/exclusion and quality assessment criteria. The performed analysis reveals that artificial neural network (ANN) as ML model, NASA as dataset, and mean magnitude of relative error (MMRE) as accuracy measure are widely used in the selected studies. ANN and support vector machine (SVM) are the two techniques which have outperformed other ML techniques in more studies. Regression techniques are the mostly used among the non‐ML techniques, which outperformed other ML techniques in about 19 studies. Moreover, SVM and regression techniques in combination are characterized by better predictions when compared with other ML and non‐ML techniques.
Reliable Intelligent Path Following Control for a Robotic Airship Against Sensor Faults

This paper presents a reliable intelligent path following control method for a robotic airship subject to sensor faults. First, an adaptive backstepping sliding mode controller is designed based on the six degrees of freedom model of airship, where the backstepping technique is used to obtain the desired velocities, and the adaptive sliding mode method is adopted to deal with the unknown model uncertainties. The stabilization of the whole path following control system is studied based on Lyapunov stability theory. Specially, since the measured data in the airship control system are interrelated, a data-driven soft sensor based on adaptive neuro-fuzzy inference system is designed to detect and isolate the sensor fault. Based on the developed detection and isolation mechanism, the airship control system still work well in the presence of sensor fault. Finally, simulations are given to demonstrate the effectiveness of the proposed path following strategy.
Magnetic Nanomaterials for Magnetically-Aided Drug Delivery and Hyperthermia

Magnetic nanoparticles have continuously gained importance for the purpose of magnetically-aided drug-delivery, magnetofection, and hyperthermia. We have summarized significant experimental approaches, as well as their advantages and disadvantages with respect to future clinical translation. This field is alive and well and promises meaningful contributions to the development of novel cancer therapies.
Analysis and Mitigation of Subsynchronous Resonance in a Korean Power Network with the First TCSC Installation

This paper presents a detailed analysis results of the effect of a thyristor-controlled series capacitor (TCSC) on subsynchronous resonance (SSR), which was first applied to a Korean power system. First, the TCSC parameters were calculated, the structure of TCSC with synchronous voltage reversal (SVR) controller was presented, and the torsional characteristics of Hanul nuclear power generator rotor were studied to investigate the natural frequency and mode shape. The test signal method was used to determine the electrical damping in the frequency range of SSR operation through an electromagnetic transient analysis program in various system configurations. The SSR phenomenon was analyzed by comparing the electrical and mechanical damping of a conventional fixed series capacitor (FSC), and the case of a TCSC installed, and the effectiveness of the TCSC without any risk of SSR was demonstrated. As a result, when installing FSC, SSR occurred under sensitive operating conditions, but SSR was prevented in the case of TCSC compensation with SVR. The results obtained in this study can be effectively applied to the installation of TCSC in real power systems.
A Distributed Cooperative Control Algorithm for Optimal Power Flow and Voltage Regulation in DC Power System

Power loss and voltage regulation are two fundamental and challenging issues in DC distributed generation system. In this paper, a multi-objective optimization problem is established to achieve trade-offs between reducing power loss and decreasing voltage deterioration by adjusting the weighting coefficients. This problem is proven to be a convex optimization under constant impedance load and constant current load. A distributed algorithm based on random coordinate descent method is developed to solve this problem without acquiring the information of line impedance. Thus, the optimal operating point of the system can be found automatically in real-time, and the deviation of optimal solution caused by the fluctuation of network parameters is avoided. In addition, the complexity of this algorithm is low and its computational requirement is reduced in practice. Finally, case studies are implemented to verify the effectiveness of the proposed algorithm under the scenarios of line parameter fluctuation, load variation, communication line failure, and plug-play capabilities.
Wireless Power Transfer Based Non-Destructive Evaluation of Cracks in Aluminum Material

Sensor design and signal conditioning of eddy-current testing are essential research areas for quantitative testing and evaluation. However, crack quantification relies on the variations of sensing mechanism and signal amplitude, which is susceptible to noise under different interferences, thus providing a limited number of features for evaluation. Therefore, this paper proposes a new concept of wireless power transfer (WPT)-based eddy-current testing and evaluation technique for the first time. The novelty of this technique is the introduction of multiple resonance frequencies as features for crack detection and characterization. Multiple resonances allow the selection of specific features for the best sample and crack characteristics. The experimental results from the artificial slots in two different aluminum samples were analyzed based on resonance points and shape of the response features. The results demonstrate that each crack width along the scan axis is proportional to the width of the two sides around it where eddy-current density is highest. Also, from the crack depth quantification, different feature extractions are compared. The results also showed that the smaller the depth of the crack, the higher the frequency feature and lower the amplitude feature.
On the efficiency of energy harvesters: A classification of dynamics in miniaturized generators under low-frequency excitation

Although motion energy harvesting at the small scales has been a research topic for over 20 years, the implementation of such generators remains limited in practice. One of the most important contributing factors here is the poor performance of these devices under low-frequency excitation. In this research, a new metric is proposed to evaluate the performance and bandwidth of generators at low frequencies. For that, a classification based on the dynamics was made. It was found that the highest efficiencies were found in single-degree-of-freedom resonators where a large motion amplification was achieved. Smaller generators can be designed by limiting the motion through end-stops at the cost of a reduced efficiency. Moreover, it was argued that upon miniaturization, resonators could be outperformed by generators using a frequency up-conversion principle.
Post-buckling analysis of non-uniformly heated functionally graded cylindrical shells enhanced by shape memory alloys using classical lamination theory

Thermal post-buckling analysis of functionally graded cylindrical shells enhanced by shape memory alloys under uniform and non-uniform heating is presented in this article. Nonlinear equilibrium equations are derived based on the classical lamination theory and von-Karman nonlinear kinematic relations and post-buckling field is investigated using Galerkin method. For temperature dependency of material properties, a numerical solution is applied to solve the nonlinear equilibrium equation using finite difference method to solve the nonlinear heat conduction equation and layered model to evaluate the thermal stress of hybrid cylindrical shells. A closed-form solution is also presented for temperature independency of material properties. Brinson model is adopted to describe the thermo-mechanical behavior of shape memory alloys. Numerical results are presented for evaluating the effects of shape memory alloy layer and functionally graded material cylindrical shells properties on suppressing of the post-buckling path of hybrid cylindrical shells.
Semi-active control of smart porous structure for sound absorption enhancement

For sound absorption of conventional porous materials, its noise-reducing ability in low frequencies is less than that in high frequency bands. A porous layer offers effective sound absorption when the thickness of layer is a quarter wavelength of the sound wave. Increasing the layer thickness is not an effective solution. Adjustment of rear air cavity volume for the porous medium has been used in practical applications to increase low frequency sound absorption. Noise reduction using only passive sound absorption characteristics is a challenge, especially when the operation conditions of noise source changes. In this study, we propose a smart porous material having noise reduction ability in the broad frequency band. We implement semi-active control by applying a magnetic reactive material to a porous medium. The smart foam proposed in this study reduced noise with adjustment of the magnitude and polarity of the magnetic field. Evaluation of its noise reduction performance is performed with the impedance tube method. Experiments are conducted for semi-active noise control of the proposed smart foam. The sound absorption characteristics are controlled efficiently with relatively low electric power consumption. A theoretical model to predict absorption characteristics is proposed using the transfer-matrix method, and its results show good agreement with measured behaviors.
Overcoming the Underestimation and Overestimation Problems in Adaptive Sliding Mode Control

Underestimation and overestimation problems are commonly observed in conventional adaptive sliding mode control (ASMC). These problems refer to the fact that the adaptive controller gain unnecessarily increases when the states are approaching the sliding surface (overestimation) or improperly decreases when the states are getting far from it (underestimation). In this paper, we propose a novel ASMC strategy that overcomes such issues. In contrast to the state of the art, the proposed strategy is effective even when an a priori constant bound on the uncertainty cannot be imposed. Comparative results using a two-link manipulator demonstrate improved performance as compared to the conventional ASMC. Experimental results on a biped robot confirm the effectiveness and robustness of the proposed method under various practical uncertainties.
Hierarchical Active Power Control of DFIG-Based Wind Farm With Distributed Energy Storage Systems Based on ADMM

A hierarchical active power control (HAPC) scheme based on the alternating direction method of multipliers (ADMM) is proposed for doubly-fed induction generator (DFIG)-based wind farms with distributed energy storage systems (ESSs). The wind farm controller optimizes the active power references for DFIG-based wind turbines (WTs) and ESSs inside the wind farm, and the aim is to minimize fatigue loads by minimizing variations of thrust force and shaft torque of WTs while tracking the dispatch command from the transmission system operator (TSO). Moreover, ESSs management is considered in the central controller and WT controllers. The solution method based on the ADMM with fast convergence is used to solve the model predictive control (MPC) optimization problem in a hierarchical manner without loss of optimality. With the ADMM, the control task is distributed to WT controllers, and the computation burden of the central wind farm controller can be efficiently reduced. A wind farm with 30 DFIG WTs was used to validate the control performance of the proposed HAPC scheme.
Enhanced Performance of Asynchronous Multi-Cell VLC System Using OQAM/OFDM-NOMA

In this paper, an offset QAM/OFDM combined with non-orthogonal multiple access (OQAM/OFDM-NOMA) modulation technique is proposed and experimentally demonstrated in a multi-user and asynchronous multi-cell visible light communication (VLC) system. OQAM/OFDM-NOMA modulation can effectively improve system capacity and flexibility owing to non-requirement of cyclic prefix (CP) and flexible power allocation strategies. We evaluate the performance comparison between the proposed OQAM/OFDM-NOMA modulation and conventional OFDM-NOMA modulation in the multi-cell VLC system. Each cell consists of cell-center users with high signal-to-noise ratios (SNRs) and cell-edge users with low SNRs. According to the measured bit error rates (BERs) for the cell-center users and the cell-edge users, better user fairness can be achieved when the power ratio is 8 dB. Moreover, in the presence of asynchronous time offset for multi-cell VLC system, the experimental results show that the asynchronous time offset has a negligible impact on the cell-edge users using OQAM/OFDM-NOMA modulation. However, the asynchronous time offset will severely degrade the system performance in conventional OFDM-NOMA based VLC system. Therefore, for the user fairness and robustness against asynchronous time-offset, the proposed OQAM/OFDM-NOMA modulation can significantly outperform the conventional OFDM-NOMA modulation in the multi-user asynchronous multi-cell VLC system.
Deep Homography Estimation and Its Application to Wall Maps of Wall-Climbing Robots

When locating wall-climbing robots with vision-based methods, locating and controlling the wall-climbing robot in the pixel coordinate of the wall map is an effective alternative that eliminates the need to calibrate the internal and external parameters of the camera. The estimation accuracy of the homography matrix between the camera image and the wall map directly impacts the pixel positioning accuracy of the wall-climbing robot in the wall map. In this study, we focused on the homography estimation between the camera image and wall map. We proposed HomographyFpnNet and obtained a smaller homography estimation error for a center-aligned image pair compared with the state of the art. The proposed hierarchical HomographyFpnNet for a non-center-aligned image pair significantly outperforms the method based on artificially designed features + Random Sample Consensus. The experiments conducted with a trained three-stage hierarchical HomographyFpnNet model on wall images of climbing robots also achieved small mean corner pixel error and proved its potential for estimating the homography between the wall map and camera images. The three-stage hierarchical HomographyFpnNet model has an average processing time of 10.8 ms on a GPU. The real-time processing speed satisfies the requirements of wall-climbing robots.
Vertical-Type Ni/GaN UV Photodetectors Fabricated on Free-Standing GaN Substrates

The authors report on a vertical-type visible-blind ultraviolet (UV) Schottky-type photodetector fabricated on a homoepitaxial GaN layer grown on free-standing GaN substrates with a semi-transparent Ni Schottky contact. Owing to the high-quality GaN drift layer with low-density threading dislocation and high electron mobility, the UV photodetector shows a high specific detectivity of more than 1012 Jones and a UV/visible discrimination ratio of ~1530 at −5 V. The photodetector also shows the excellent self-powered photo-response and a high signal-to-noise ratio of more than 104 at zero voltage. It is found that a relatively lower growth rate for the GaN epilayer is preferred to improve the performance of the Schottky-type photodetectors due to the better microstructure and surface properties.
MONTHLY CLOUD FREE LOS TIME SERIES GENERATOR FOR OPTICAL SATELLITE LINKS

—In this Letter, a space time synthesizer for the generation of monthly cloud free line of sight (CFLOS) statistics is presented. The proposed monthly time series generator is based on the synthesis of 3D cloud ﬁelds using Stochastic Diﬀerential Equations. Monthly Integrated Liquid Water Content (ILWC) statistics are used as inputs, and the temporal and spatial correlation of clouds is considered. The monthly variability of the cloud coverage is predicted, and the CFLOS is estimated taking into account the elevation angle of the slant path and the altitude of the station for high altitude optical ground stations. Finally, CFLOS numerical results are reported, and some signiﬁcant conclusions are drawn.