Applied Sciences — Open Access Journal

Strabismus is a common vision disease that brings about unpleasant influence on vision, as well as life quality. A timely diagnosis is crucial for the proper treatment of strabismus. In contrast to manual evaluation, well-designed automatic evaluation can significantly improve the objectivity, reliability, and efficiency of strabismus diagnosis. In this study, we have proposed an innovative intelligent evaluation system of strabismus in digital videos, based on the cover test. In particular, the video is recorded using an infrared camera, while the subject performs automated cover tests. The video is then fed into the proposed algorithm that consists of six stages: (1) eye region extraction, (2) iris boundary detection, (3) key frame detection, (4) pupil localization, (5) deviation calculation, and (6) evaluation of strabismus. A database containing cover test data of both strabismic subjects and normal subjects was established for experiments. Experimental results demonstrate that the deviation of strabismus can be well-evaluated by our proposed method. The accuracy was over 91%, in the horizontal direction, with an error of 8 diopters; and it was over 86% in the vertical direction, with an error of 4 diopters. Full article

This paper aimed to study the influence of proprioception and visual focus of attention on predicting elbow angles. The experiments were conducted in two directions with three psychological factors in each direction. Then, the method of pattern recognition was used to predict the elbow angles. Finally, the accuracy of the predicted error was verified by using the root mean square error, and the coherence coefficient of the myocardium was used to analyze the effect of various factors on the recognition accuracy. The results showed that a change in the subject’s external focus of attention and proprioception improved the recognition accuracy of the elbow. The methods and results of the paper can be the basis to optimize surface electromyography (sEMG) control. Finding the relationship between psychological factors and control could enable improvements in the performance of human–computer interactions. Full article

Zirconia materials are frequently used in dental applications due to their excellent strength and their tooth-like aspect. Standard yttria stabilized zirconia (Y-TZP) ceramics suffer, however, from moderate toughness and vulnerability to low-temperature degradation. In this study, 1Y6Ce-TZP materials reinforced with different amounts of alumina and/or strontium hexaaluminate were manufactured by slip casting and pressureless sintering at different temperatures to assess their mechanical properties, microstructure, phase composition, and low-temperature degradation stability. Results show that these materials exhibit a high fracture resistance of 10–12 MPa√m, a bending strength between 700–950 MPa, and a Vickers hardness of 1100–1200 HV10. Strontium hexaaluminate (SA6) precipitates were formed in situ by reaction of alumina and strontium zirconate. Although crack deflection at SA6 platelets was clearly visible, a net toughening was not observed. Accelerated ageing tests at 134 °C/3 bar water vapor pressure showed best results for mixed alumina/SA6 reinforcements and a sintering temperature of 1500 °C. Mehl-Avrami-Johnson plots used to describe the ageing kinetics showed clear indications of different ageing mechanisms due to the introduction of the SA6 phase. Full article

Scientists and engineers involved in the design of complex system solutions use computational workflows for their evaluations. Along with growing system complexity, the complexity of these workflows also increases. Without integration tools, scientists and engineers are often highly concerned with how to integrate software tools and model sets, which hinders their original research or engineering aims. Therefore, a new framework for streamlining the creation and usage of automated computational workflows is introduced in the present article. It uses state-of-the-art technologies for automation (e.g., container-automation) and coordination (e.g., distributed message oriented middleware), and a microservice-based architecture for novel distributed process execution and coordination. It also supports co-simulations as part of larger workflows including additional auxiliary computational tasks, e.g., forecasting or data transformation. Using Apache NiFi, an easy-to-use web interface is provided to create, run and control workflows without the need to be concerned with the underlying computing infrastructure. Initial framework testing via the implementation of a real-world workflow underpins promising performance in the realms of parallelizability, low overheads and reliable coordination. Full article

Power electronic transformers (PETs), as the core devices of the energy internet, are the key to achieve both effective consumption for renewable energy and the safe and coordinated operation for AC/DC hybrid system. In order to overcome the shortcomings of the existing PETs, a novel PET with an improved structure that applicable for multi-voltage level AC/DC hybrid distribution network is proposed. The topology of the proposed PET is analyzed, and the corresponding control methods are suggested for different parts. The input stage utilizes the modular multilevel converter structure and applies the virtual synchronous machine control strategy to enhance the inertia and damping of the system. The power of the output stage is adjusted flexibly and that enables the PET to provide certain power support to the upper grid and participate in its primary frequency regulation. A combined connection of input-series output-series and input-series output-parallel is applied for the dual-active-bridge modules of the isolation stage to enable network interconnection and electrical isolation of AC/DC grids with significantly different voltage levels. A power coordinated control method is then proposed to meet the power demand of the distribution networks connected to the output stage and ensure stable operations of PET simultaneously. The reliability and efficiency of the proposed PET topology and control strategy for AC/DC hybrid distribution network are finally verified via PSCAD/EMTDC simulation. Full article

Multibody models have not yet been evaluated for reconstructing head kinematics during sports impacts. Accordingly, the goal of this study was to utilise whole-body motion data from twenty upper and mid/lower trunk rugby shoulder tackles recorded in a marker-based 3D motion analysis laboratory to assess the MADYMO human body passive ellipsoid model for head kinematic reconstruction. Head linear and angular velocity during the tackle for the multibody model predictions and 3D motion laboratory measures were recorded for the ball carrier. Examined were the linear and angular velocity, as well as the absolute and percentage differences. For upper trunk tackles, the median percentage error (with quartiles) for the MADYMO predictions were 10% (6% to 45%) and 23% (16% to 39%) for change in head linear and angular velocity, respectively. For mid/lower trunk tackles, the median percentage error (with quartiles) for the MADYMO predictions were 46% (33% to 63%) and 60% (53% to 123%) for change in head linear and angular velocity, respectively. In conclusion, the model is currently unsuitable for reconstruction of head kinematics during individual rugby union tackle cases. Full article

Several phenomena are represented by directional—angular or periodic—data; from time references on the calendar to geographical coordinates. These values are usually represented as real values restricted to a given range (e.g., $[0,2\pi )$), hiding the real nature of this information. In order to handle these variables properly in supervised classification tasks, alternatives to the naive Bayes classifier and logistic regression were proposed in the past. In this work, we propose directional-aware support vector machines. We address several realizations of the proposed models, studying their kernelized counterparts and their expressiveness. Finally, we validate the performance of the proposed Support Vector Machines (SVMs) against the directional naive Bayes and directional logistic regression with real data, obtaining competitive results. Full article

In the supply chain management literature, various mobile radio frequency identification (RFID) protocols have been proposed for minimizing cargo theft during transport while ensuring the integrity of the entire cargo load or transferring ownership of a tagged item to another owner. These protocols are generally called grouping proof protocols and ownership transfer protocols, respectively. However, no protocol has been proposed that can achieve both requirements. In this paper, we propose a novel designated ownership transfer with grouping proof protocol that simultaneously generates grouping proofs and authenticates the consistency between the receipt proof and pick proof while ensuring that ownership of the cargo is transferred to the new designated owner in one attempt. In addition, the proposed scheme is robust against attacks (such as replay, denial-of-service, and denial-of-proof attacks) and has security features, such as forward/backward secrecy and message integrity. Full article

Due to the interconnected scheme of multiple components, such as distributed generators, storage systems, and loads through converters to a common bus in DC microgrids, the possibility of fault occurrence is increasing significantly. Meanwhile, due to the huge and rapid increase of short-circuit currents, the development of a small- and large-scale DC system requires a reliable and fast protection system to ensure fault clearance and maintain safety for the rest of the system. Thus, fault protection has been focused on as one of the most critical issues in a direct current network. The application of traditional circuit-breakers for DC fault protection has the drawback of slow operation, which requires a high rating power equipment. Recently, the high speed and excellent performance capabilities of semiconductor breakers have attracted a lot of attention and been considered as an optimal solution for fast DC fault interruption. In this study, a bidirectional Insulated-Gate Bipolar Transistor (IGBT) semiconductor breaker, suitable for the fault protection of low-voltage DC networks, is proposed. The operating characteristics of this breaker are based on changes in the circuit current and terminal voltage of IGBTs. It detects the abrupt change of the terminal voltage as an abnormal condition and isolates the faulted branch in a short time to prevent the operation disturbance in the healthy part of the network. Therefore, for the entire protection of a typical 400V DC-microgrid cluster, breakers need to be integrated and examined in each branch and the interconnected lines. The proposed protection method in this study is examined in a Simulink^®/MATLAB environment to analyze and assess its operation. Full article

In this paper, a hybrid strategy of rules and statistics is employed to implement the Uyghur Noun Re-inflection model. More specifically, completed Uyghur sentences are taken as an input, and these Uyghur sentences are marked with part of speech tagging, and the nouns in the sentences remain the form of the stem. In this model, relevant linguistic rules and statistical algorithms are used to find the most probable noun suffixes and output the Uyghur sentences after the nouns are re-inflected. With rules of linguistics artificially summed up, the training corpora are formed by the human–machine exchange. The final experimental result shows that the Uyghur morphological re-inflection model is of high performance and can be applied to various fields of natural language processing, such as Uyghur machine translation and natural language generation. Full article

Crowdsourcing has the advantages of being cost-effective and saving time, which is a typical embodiment of collective wisdom and community workers’ collaborative development. However, this development paradigm of software crowdsourcing has not been used widely. A very important reason is that requesters have limited knowledge about crowd workers’ professional skills and qualities. Another reason is that the crowd workers in the competition cannot get the appropriate reward, which affects their motivation. To solve this problem, this paper proposes a method of maximizing reward based on the crowdsourcing ability of workers, they can choose tasks according to their own abilities to obtain appropriate bonuses. Our method includes two steps: Firstly, it puts forward a method to evaluate the crowd workers’ ability, then it analyzes the intensity of competition for tasks at Topcoder.com—an open community crowdsourcing platform—on the basis of the workers’ crowdsourcing ability; secondly, it follows dynamic programming ideas and builds game models under complete information in different cases, offering a strategy of reward maximization for workers by solving a mixed-strategy Nash equilibrium. This paper employs crowdsourcing data from Topcoder.com to carry out experiments. The experimental results show that the distribution of workers’ crowdsourcing ability is uneven, and to some extent it can show the activity degree of crowdsourcing tasks. Meanwhile, according to the strategy of reward maximization, a crowd worker can get the theoretically maximum reward. Full article

Novel nanomaterials, including metallic nanoparticles obtained via green synthesis (gNPs), have a great potential for application in biotechnology, industry and medicine. The special role of gNPs is related to antibacterial agents, fluorescent markers and carriers for drug delivery. However, application of gNPs for construction of amperometric biosensors (ABSs) is not well documented. The aim of the current research was to study potential advantages of using gNPs in biosensorics. The extracellular metabolites of the yeast Ogataea polymorpha were used as reducing agents for obtaining gNPs from the corresponding inorganic ions. Several gNPs were synthesized, characterized and tested as enzyme carriers on the surface of graphite electrodes (GEs). The most effective were Pd-based gNPs (gPdNPs), and these were studied further and applied for construction of laccase- and alcohol oxidase (AO)-based ABSs. AO/GE, AO-gPdNPs/GE, laccase/GE and laccase-gPdNPs/GE were obtained, and their analytical characteristics were studied. Both gPdNPs-modified ABSs were found to have broader linear ranges and higher storage stabilities than control electrodes, although they are less sensitive toward corresponding substrates. We thus conclude that gPdNPs may be promising for construction of ABSs for enzymes with very high affinities to their substrates. Full article

This paper presents a new type of solar cellwith enhanced optical-current characteristics using an ultra-thin CuIn_1−xGa_xSe₂ hole-transporting material (HTM) layer (<400 nm). The HTM layer was between a bi-layer Mo metal-electrode and a CH₃NH₃PbI₃ (MAPbI₃) perovskite active absorbing material. It promoted carrier transportand led to an improved device with good ohmic-contacts. The solar cell was prepared as a bi-layer Mo/CuIn_1−xGa_xSe₂/perovskite/C₆₀/Ag multilayer of nano-structures on an FTO (fluorine-doped tin oxide) glass substrate. The ultra-thin CuIn_1−xGa_xSe₂ HTM layers were annealed at various temperatures of 400, 500, and 600 °C. Scanning electron microscopy studies revealed that the nano-crystal grain size of CuIn_1−xGa_xSe₂ increased with the annealing temperature. The solar cell results show an improved optical power conversion efficiency at ~14.2%. The application of the CuIn_1−xGa_xSe₂ layer with the perovskite absorbing material could be used for designing solar cells with a reduced HTM thickness. The CuIn_1−xGa_xSe₂ HTM has been evidenced to maintain a properopen circuit voltage, short-circuit current density and photovoltaic stability. Full article

In order to ameliorate the anterior knee pain or peripheral pain around the tibia caused by patellar lateral subluxation, we evaluated the kick training effects of standing or sitting postures in strengthening the vastus medialis obliquus (VMO) on the quadriceps femoris muscle. A total of 83 subjects (45 male; 38 female) in both sitting and standing positions performed 10° to 90° leg lift and kick training. Among the male group, the effect of the sitting posture was better than that of the standing posture, 74.31% of the former achieved the training goal. In the female group, the effect of a standing posture was better than that of a sitting posture, for which only 37.71% of the latter achieved the training purpose. However, a ratio of 84.34% in the female group showed that the strength of VMO on the quadriceps femoris muscle generated by leg kicking was greater than the strength generated by walking. While it was impossible to immediately achieve a greater effect of VMO on the quadriceps femoris muscle than vastus lateralis on the quadriceps femoris muscle, leg kicking did achieve the objective of enhancing the strength of VMO on the quadriceps femoris muscle. Full article

This paper proposes a new optical design that will cooperate with 3D image technology, infrared spectrum technology, future medical diagnostics, the cloud, and big data analysis. We first conducted image recognition experiments to compare the pros and cons of 2D and 3D frameworks in order to make sure that the optical and mechanical framework of a glasses-type 3D ophthalmoscope would be a better choice. The experimental results showed that a 3D image recognition rate (90%) was higher than a 2D image recognition rate (84%), and hence the 3D mechanism design was selected. The glasses-type 3D ophthalmoscope design is primarily based on the specification of indirect ophthalmoscope requirements and two working spectrums: a near infrared and a visible spectrum. The design is a 2.5x magnification fixed focal telecentric relay system with a right-angle prism, which uses a large aperture to increase the amount of incident light (F/# = 2.0). As the infrared spectrums that have better transmittance towards human eye tissue are 965 nm and 985 nm, so that we took account of the visible spectrum and the near-infrared spectrum simultaneously to increase the basis of the physician’s diagnosis. In this research, we conclude that a wearable ophthalmoscope can be designed optically and mechanically with 3D technology, an infrared and a visible working spectrum and further, possibly in cooperation with the cloud and big data analysis. Full article

This paper proposes a dual-stream 3D space-time convolutional neural network action recognition framework. The original depth map sequence data is set as the input in order to study the global space-time characteristics of each action category. The high correlation within the human action itself is considered in the time domain, and then the deep motion map sequence is introduced as the input to another stream of the 3D space-time convolutional network. Furthermore, the corresponding 3D skeleton sequence data is set as the third input of the whole recognition framework. Although the skeleton sequence data has the advantage of including 3D information, it is also confronted with the problems of the existence of rate change, temporal mismatch and noise. Thus, specially designed space-time features are applied to cope with these problems. The proposed methods allow the whole recognition system to fully exploit and utilize the discriminatory space-time features from different perspectives, and ultimately improve the classification accuracy of the system. Experimental results on different public 3D data sets illustrate the effectiveness of the proposed method. Full article

Consumption of produce contaminated with pathogens of fecal origin is the most common source of food borne illnesses. Current practice is to visually survey fields for evidence of fecal contamination, and to exclude problematic areas from harvest. Bird excrement is known to contain human pathogens, and is often not detectable in produce fields using current survey methods. The goal of this project was to identify parameters for optical detection of bird excrements to support development of instruments to be used to supplement existing visual surveys. Under daylight ambient conditions, results suggested that reflectance imaging at around 500–530 nm or 610–640 nm could be used to detect excrements from the three bird species tested. Images were acquired using ad hoc camera parameters; however, normalizing intensities for individual images at 525 nm and using a fixed detection threshold allowed detection of 100% of bird excrements with no false positives against the background that consisted of local soil and fresh romaine and spinach leaves. Similar results were obtained using fluorescence imaging. Fluorescent imaging was accomplished in a darkened room using 405-nm illumination. The largest consistent differences in intensity responses between excrements and the brightest non-excrement object in the background matrix occurred at around 550 nm. Results suggested that using reflectance or fluorescence imaging for detection of bird excrements could be a valuable tool for reducing risks of consuming contaminated produce. One possibility would be to incorporate appropriate reflectance imaging capabilities in drones under the control of the individuals currently conducting field surveys. Full article

Solar energy is an inexhaustible source of clean energy. Meanwhile, supercritical carbon dioxide has excellent characteristics such as easy access to critical conditions, high density, and low viscosity, making it one of the most popular circulating working fluids in solar power generation technology. However, solar power generation systems are severely affected by geographical distribution, seasonal variations and day-night cycles. Therefore, efficient and adaptable turbine design is the key to realize supercritical carbon dioxide solar power generation technology. In this paper, the initial thermodynamic design of 10 MW S-CO₂ three-stage axial turbine is completed by self-developed thermodynamic design software, and the key thermodynamic and structural parameters are obtained. The optimal design of turbine and its aerodynamic performance at rated operating conditions are obtained by using a three-dimensional aerodynamic numerical analysis and optimization method. At last, nine off-design conditions are analyzed in detail. The results show that the designed turbine output power is 10.37 MW and the total-total efficiency is 91.60%. It can operate efficiently and steadily in the range of output power from 16.2% to 155.9%. It can adapt to the variable operating conditions of solar power generation system and meet the design requirements. Full article

In this study, using electrolytic reducing ionic water (S-100^®), a novel surface treatment method safely and easily modifying the surface properties was evaluated in vitro and in vivo. Ti-6Al-4V disks were washed and the disks were kept standing on a clean bench for one and four weeks for aging. These disks were immersed in S-100^® (S-100 group), immersed in ultra-pure water (Control group), or irradiated with ultraviolet light (UV group), and surface analysis, cell experiment, and animal experiment were performed using these disks. The titanium surface became hydrophilic in the S-100 group and the amount of protein adsorption and cell adhesion rate were improved in vitro. In vivo, new bone formation was noted around the disk. These findings suggested that surface treatment with S-100^® adds bioactivity to the biologically aged titanium surface. We are planning to further investigate it and accumulate evidence for clinical application. Full article