Robotic Systems and Applications
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Simulative analysis on large local deformation features of single-shell and double-shell cylinders subjected to underwater explosion
Get PDFSimulative studies on a series of the cylinders subjected to underwater explosion were presented using coupled acoustic-structural analysis in ABAQUS in order to analyze the large local deformation feature and the influence of the outer water tank. The results revealed that large inward local deformation occurs on the front side of the cylinder, and the plastic hinge locates near the boundary of the spherical projection of the explosion to the cylinder with an approximate elliptic type. The inner water and the outer shell’s thickness of double-shell cylinders have great influence on the large local deformation feature of the inner shell, and with the increase of the outer shell’s thickness, large local inward deformation occurs on the back side of the cylinder, which is caused by the local jet effect of the inner water. The research can provide reference to the design and assessment of underwater anti-explosion structures
Improvement of maintenance management through Lean Philosophy and Industry 4.0
Get PDFFor companies to be able not only to survive, but also to differentiate themselves in the current global market scenario, all their functional areas must be in line with short, medium, and long-term management objectives and policies. The performance and competitiveness of companies depend on the behaviour of their production system, so an ambitious and adequate maintenance management is necessary. In this way, companies seek to adopt new methodologies and approaches to maintenance management that allow them to prepare maintenance for the challenges of Lean Philosophy and Industry 4.0. The Lean philosophy aims to do more and more with less and less, that is, using less equipment, less human effort, less space, and time, trying to offer customers exactly what they want, at the right time. On the other hand, Industry 4.0 is based on intelligent factories with production processes with a computer interface between people, machines, and resources, through extensive communication networks that combine the virtual and the real world, to obtain all integrated processes generating thus a real-time information system. Thus, an adequate maintenance management system contributes not only to improve maintenance performance as well as the production system. The maintenance management system, when combined with Lean Philosophy and Industry 4.0 concepts, makes it more efficient and effective. To improve maintenance performance, a system that combines these three concepts is proposed
An efficient solar water desalination system using natural vacuum pressure
Get PDFAn innovative design of a solar natural vacuum desalination (SNVD) system is proposed and investigated. To obtain a vacuum pressure in a desalination chamber its height is considered as 9.5 m. The waste heat in the system is efficiently utilized for both brine and distilled water. Seawater is preheated by the produced warm water, then, it is heated again by the outlet rejected hot brine before it is charged into the evaporation chamber. In addition, inlet pure water to a flat-plate collector is preheated by the condensation latent heat of the evaporated vapor from the evaporation chamber. Later, the outlet hot water from the collector is used as a heat source to the evaporation process. An optimum design of the system components was provided under the actual weather conditions for the shortest day of the year. It was found that the collector area is required to be 23 m2 to produce 66.6 liter of distilled water during. A mathematical modeling of the system was provided to establish a transient simulation and investigate the hourly performance of the system. Based on the annual performance of the system, the system can produce 76.5 liter of distilled water daily that is corresponding to 3.5 liter per one quadratic meter of collector. The annual average specific productivity of the system is obtained as 1.44 liter per kWh of solar radiation. Moreover, the maximum annual production is estimated as 92.88 liter of distilled water per day. Accordingly, the evaporation ratio (ER) is dependent on the solar irradiation and the annual average is found 0.0175 (or 1.75 %) where the gain output ratio (GOR) was estimated as 0.97 on yearly average basis
Is jaw functional orthopedics an efficient tool to treat anterior open bite? A retrospective study
Get PDFAnterior Open Bite (AOB) is a malocclusion for which the choice of a treatment protocol it is challenging. There are some protocols that have been shown to be effective for open bite treatment. The aim of this investigation was to study the behavior of overbite during AOB treatment with Jaw Functional Orthopedics (JFO). The behavior of overbite was studied retrospectively in 17 patients treated in the Specialization Course in (JFO – ABO Muriaé (Muriaé, MG Brazil). Monthly overbite measurements in millimeters were taken with a pachymeter and the data were stored in an individual paper worksheet. Data obtained before functional appliance installation (T0) and after 12-months of treatment (T1) were compared. Wilcoxon non-parametric test for 2 paired samples was use for statical treatment of the data. P= 0.003 for overbite comparison T1-T0. It could be concluded that Functional orthopedic appliance has shown to be an effective tool for treating anterior open bite in the sample studied. Further studies, mainly Randomized Clinical Trials, with larger samples are necessary to confirm this result and to study stability and skeletal behavior in anterior open bite treated with Jaw Functional orthopedics
Effect of warp and weft uniaxial tension on the permeability of sand covered with geotextile
Get PDFThe permeability of sand covered with geotextile is affected by the permeability of geotextile, which is related to the tensile state of the geotextile. Considering the weaving mode of geotextile, the effects of warp tension and weft tension on the permeability of sand covered with geotextile were studied by experiment. Four different specifications of geotextiles were selected for warp and weft tension respectively. The changes of permeability parameters of sand covered with geotextile under non tension, warp and weft tension were measured by vertical permeability instrument, and the effects of warp and weft tension on permeability parameters such as seepage velocity, sand loss and gradient ratio were analyzed. The test results show that the water permeability and anti silting performance of the geotextile increase with the increase of tensile strain, and the soil conservation performance decreases with the tensile strain increasing. Meanwhile, the relationship between permeability and warp tensile strain is not monotonic. When the warp tensile strain 3%, the water permeability and anti silting performance of geotextile are the weakest, and the soil conservation performance is the strongest
Erratum: Feature-based performance of SVM and KNN classifiers for diagnosis of rolling element bearing faults
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Structural simulation analysis of high pressure common rail pipe
Get PDFAs one of the key components of the common rail system, the accuracy of pressure field and velocity field analysis of the common rail pipe is related to the service reliability. In order to obtain the velocity and pressure distribution that difficult to be measured in the experiment, this paper considers using three-dimensional modeling and establishing the three-dimensional model of oil flow in the common rail pipe based on the fluid simulation software, and then obtains the velocity field and pressure field distribution of the common rail pipe through numerical simulation. The cone angle at the nozzle structure of common rail pipe is compared and analyzed. Meanwhile the most appropriate cone angle’s processing angle among the commonly used processing cone angles is obtained, which improves the rationality of common rail pipe structure processing. It is great significance to the subsequent rail pressure stabilization analysis of common rail pipe
Identification of shallow cracks in rotating systems by utilizing convolutional neural networks and persistence spectrum under constant speed condition
Get PDFThe positive benefits of early faults detection in rotating systems have led scientists to develop automated methods. Although unbalancing is the most prevalent defect in rotor systems, this fault normally is accompanied by other defects such as crack. In this article, an effective self-acting procedure is addressed in identifying shallow cracks in rotor systems throughout the steady-state operation. To classify rotor systems suffering cracks with three various depths, firstly, healthy and cracked systems are modeled by employing the finite element method (FEM). In the following, systems' vibration signals are calculated in different situations numerically; for pre-processing stage, the persistence spectrum is implemented. Finally, by using a supervised convolutional neural network (CNN), rotor systems are classified by regarding the crack depths. The result of the testing step revealed that this hybrid method has rational capacity in distinguishing shallow cracks in steady-state operation where many other methods are somehow powerless