Journal of Mechanical Engineering, Automation and Control Systems
Not a member yet
1200 research outputs found
Sort by
Plagiocephaly and malocclusion
Get PDFThe term plagiocephaly means oblique head. Most skull deformities are a result of intrapartum or utero molding but can be caused by congenital torticollis and after birth due to persistent head position of newborns staying in one head position for a long time and abusive use of strollers, car seats, car seats, swings. Its prevalence is growing fast, in 30 years it passes from 1 in each 300 babies in early nineties to 16 to 48 % in 2020. The aim of this paper is bringing the light to some serious conditions of treatment protocols in individuals with plagiocephaly. The skull deformity causes facial asymmetry that are not treatable by orthopedic or orthodontic intra or extra oral appliances, nor orthognathic surgery. Well, despite the fact that the patient or the tutors have to be notified of the facial asymmetry that persists, functional limitations will be presented. In more than 30 years of clinical experience treating these patients it was never sought the 4 first permanent molars and the 4 canines in the same Angle’s Class. In one side can be seen Class 1, but on the other it will be finding class 2 or class 3, the case reported exemplifies it, and the worst, mastication guidance will have to be very carefully done since, in most cases if it is tried to adjust the inferior and superior dental midline the vertical asymmetry of the occlusal plane (minimum vertical dimension) will worsen. Really there is no unique treatment protocol and it has to be considered case by case. It is time to deepen the knowledge in this area since the prevalence is growing. Based on the case reported, non-treated plagiocephaly can bring serious limitations to malocclusion treatment results. Further studies are necessary to a better understanding of the situation plagiocephaly versus malocclusion
An improved semi-supervised prototype network for few-shot fault diagnosis
Get PDFThe collection of labeled data for transient mechanical faults is limited in practical engineering scenarios. However, the completeness of sample determines quality for feature information, which is extracted by deep learning network. Therefore, to obtain more effective information with limited data, this paper proposes an improved semi-supervised prototype network (ISSPN) that can be used for fault diagnosis. Firstly, a meta-learning strategy is used to divide the sample data. Then, a standard Euclidean distance metric is used to improve the SSPN, which maps the samples to the feature space and generates prototypes. Furthermore, the original prototypes are refined with the help of unlabeled data to produce better prototypes. Finally, the classifier clusters the various faults. The effectiveness of the proposed method is verified through experiments. The experimental results show that the proposed method can do a better job of classifying different faults
Introduction of the distribution of Cs in Cu(In,Ga)Se2 photovoltaic absorbers following post-deposition treatment with CsF
Get PDFIn recent years, the device performance of Cu(In,Ga)Se2 (CIGS) solar cells has been improved by heavy alkali element post-deposition treatment (Alkali-PDT). Therefore, it is of great significance to study the mechanism of enhancing CIGS device performance through Alkali-PDT. One aspect to be studied is the distribution of heavy alkali elements in the absorber. In this work, the distribution of the heavy alkali element Cs in the absorber after post deposition treatment of CsF (CsF-PDT) and its effect on the device performance are investigated. The experimental results indicate that Cs can enter both the grain interior (GI) and grain boundaries (GB) via the Cu vacancy (VCu). By comparing the distribution of Na and Cs in the film, it can be noticed that Na is mainly distributed at the GB, while Cs is not differently distributed between the GB and GI. This is mainly due to the fact that the presence of Na at GB inhibits the accumulation of Cs there. The distribution of Cs is beneficial in improving the device’s performance by passivating defects, such as InCu
Simulation of locomotion conditions of an enhanced vibration-driven in-pipe robot
Get PDFThe paper aims to analyze the improved design of an in-pipe vibration-driven robot, which is equipped with a self-locking mechanism, electromagnetic exciter, and size-adapting devices. The study focuses on examining the robot’s locomotion conditions at different working regimes. The research methodology contains four main stages: analysis of the design peculiarities of the enhanced wheeled in-pipe vibration-driven robot; developing a simplified dynamic diagram and deriving the differential equations to describe its locomotion conditions; carrying out numerical modeling with the help of Mathematica software to analyze the robot’s basic dynamic parameters; conducting virtual experiments and testing the robot locomotion characteristics by means of the computer simulation in SolidWorks Motion software. The results obtained include the time-based data on the robot’s displacement, speed, acceleration, and consumed power under different operating conditions, such as varying forced frequencies and excitation force amplitudes. The novelty of this investigation lies in identifying efficient working regimes for the improved wheeled vibration-driven robot intended for moving inside the pipelines. Future research will focus on developing a full-scale experimental prototype of the robot and conducting laboratory investigations at different working regimes. The findings of this research are valuable for scientists and engineers involved in the study and design of similar vibration-driven locomotion systems
Assessment of the impact of TE33A diesel locomotive wheelsets on the railway track in a straight section of the track
Get PDFThe purpose of the article is an experimental study of the impact of the wheelsets of a mainline diesel locomotive on the railway track on straight sections of the track. The measurements were performed on a vibration measuring device consisting of MV25 DV type sensors and an oscillation converter for a digital signal. It is proved that the indicators of dynamic characteristics comply with regulatory requirements. As a result of the conducted research, digital data was collected from the ADC and general monitoring was carried out. Measurement and signal processing are carried out using special software of a personal computer such as a “Notebook”. Vertical static load of a wheelset of a railway rolling stock unit on rails: the load of a railway rolling stock unit on rails attributed to one wheelset, taking into account the actual location of the center of gravity of the superstructure
Effect of welding axial stresses on the strength of a welded pipe joint with a defect
Get PDFThe use of an integrated approach to determining the static strength of operated main pipelines with surface defects makes it possible to take into account the effect of residual weld stresses in combination with operational loads. In this case, it is important to determine the nature of the welding stress distribution for welded structures made of high-strength steels. Here, there is non-uniformity of stresses concerning magnitude and gradient, which is due to technological methods. A mathematical model of the experimental-calculation method is proposed. Such a model allows describing such stresses. A two-parameter criterion for brittle-tough fracture of a material which takes into account the influence of residual stresses is used. It is shown that the combination of residual stresses and operating loads has a significant effect on the safety factor. At the same time, conditions are possible under which compressive residual stresses have a favourable effect on the static strength of a pipeline with a defect
Prediction of concrete sulfuric acid corrosion evaluation index model based on grey system theory
Get PDFIn order to predict the impact of sulfate corrosion on concrete, based on grey system theory, GM(1,1) and GM(1, N) models were used to predict and analyze the compressive strength and relative dynamic elastic modulus of concrete under sulfuric acid corrosion. The results show that the prediction error of the GM(1,1) model for concrete sulfate corrosion attenuation is within 5 %, and the residual size test of the GM(1, N) model for concrete sulfate corrosion is within 10 %
Common fixed-point theorem for commuting maps on a metric space
Get PDFSeveral novel uses of theorems for fixed points in commuting mapping in a fully metric domain are presented. Several conclusions from full metric fixed point theory are improved and extended by our work. Our proofs are inspired by the study of commuting mappings [B. Fisher and S. Sessa, on a fixed point theorem of Gregus, 1986] and [P. Sumati Kumari, Fixed and periodic point theory in certain spaces, 2013]
Photogrammetry protocol in babies with congenital torticollis: part 1 – inter-arch intraoral assessment
Get PDFTorticollis is defined as an imbalance of the sternocleidomastoid muscle (SCM), with less extension of the neck, resulting in a preference to turn the head more from one side to the other. The characteristics frequently found are: ear contralateral to the torticollis displaced forward, facial asymmetry, and contralateral occipital flattening, as well as a smaller ipsilateral eye, causing misalignment of the eyes. This condition can also cause mandibular inclination (MI), in the frontal plane, with a difference in opening between the maxilla and mandible from one side or the other. The diagnosis and treatment of torticollis are routinely carried out by the physiotherapist and the diagnosis of this mandibular inclination is traditionally through visual examination. This assessment of mandibular inclination, carried out by the dentist, in an objective manner, can contribute to the diagnosis and also to the monitoring of proposed treatments that should reduce mandibular asymmetries. The objective of this study was to create a protocol for objective measurement of the distance between the maxilla and mandible, on the right and left sides, using photogrammetry, to detect whether mandibular inclination can be observed by the shorter inter-arch distance on the side corresponding to the torticollis. Case reports of two babies (1 baby aged 9 months and another aged 1 year and 1 month), diagnosed with congenital torticollis. Photogrammetry was carried out: the babies were positioned on a dental stretcher and photographed in maximum opening, intermediate, and closing positions. Using the photos and the IMAGE J program, measurements between the maxilla and mandible were taken (see photogrammetry description). Results: The measurement protocol used in both babies confirmed the greater mandibular inclination by approaching the hemi-arch corresponding to the side of the torticollis, compared to the opposite side. Objective measurement of mandibular inclination can be part of the timely diagnosis for congenital torticollis. Studies with an adequate sample size and methodology are necessary to confirm this diagnostic tool
Influence of sliding wear on contact characteristics based on 3-D wheel/rail contact model
Get PDFDuring the process of starting, braking and running of the train, sliding contact between wheel and rail occurs. The wear caused by sliding contact exerts a noteworthy influence on the contact characteristics of wheel/rail. To analyze these characteristics, a three-dimensional wheel/rail contact wear model is established, and the contact characteristics at different wear depths are studied. The results indicate that at initial contact, the wheel/rail contact patch is approximately elliptical in shape and its area is 122.5 mm2. The von Mises stress of the wheel and rail is maximum in the subsurface at a distance of 2 mm from the contact interface, with maximum values of 559 MPa and 628 MPa respectively. When the wear depth is less than 0.5 mm, the wear depth, contact area and size increase quickly. As the amount of wheel contact wear increases, the maximum contact stress gradually decreases and the contact stress becomes uniform. In addition, the calculation results indicate that the contact patch shape does not always remain elliptical, the shape can change from elliptical to rectangular as the wear depth increases. As the increasing of wear amount, the contact stress gradient on the inner side of wheel contact surface increases