Robotic Systems and Applications
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A study on the acoustic characteristics of the sound-absorbing structure in single-column UHV Shunt reactors
Get PDFSingle-column UHV shunt reactors usually generate large noises with long wavelengths. For this reason, the noises along the substation boundaries may exceed the standards. We aimed at noise control of single-column UHV shunt reactors in the present study. Based on the noise characteristics of single-column UHV shunt reactors, we employed an acoustic impedance test apparatus and studied the influences of different structural parameters on the acoustic performance of the compound impedance sound-absorbing structure. The results showed that the compound impedance sound-absorbing structure had a better sound-absorbing performance at low frequencies if a microperforated plate was introduced with basalt cotton as the filler. Besides, as the surface density, thickness, size of the dorsal cavity, and size of the intermediate cavity increased, the sound absorption coefficient at low frequencies increased. After the surface density increased to a certain level, the increase rate of the sound-absorbing performance dropped suddenly. Moreover, the intermediate cavity achieved a lesser enhancement of sound-absorbing performance at low frequencies than the dorsal cavity
Salival biomarkers in inflamatory oro-cranio-cervical inflamatory alterations
Get PDFDuring the COVID 19 pandemic, the general population suffered from high degrees of stress, the consequence of which was an increase in myofascial pain syndrome. This inflammatory ailment which affects soft tissues causes pain, muscular rigidity, and modifies posture due to hyperactivity. A state of muscular ischemia leads to structural and chemical changes, and to variations in saliva’s electrical conductivity. The objective of this research was to measure the changes in pH and electrical conductivity of saliva samples, and to use these as biomarkers during therapeutical Maxillary Functional Orthopedics (Planas’ Simple Indirect Tracks and Simões Network 20). All the subjects that took part in the study evidenced changes in the beforementioned biomarkers, as well as clinical improvement of their symptoms
Corporeal-composition indicators, and physiological alterations in dental eruption
Get PDFWorldwide, obesity leads to major diseases in adults. Infants are affected as well, particularly because of growth and development issues. In this article we describe cases of early dental eruption in overweight and obese children, almost 1 year earlier than expected. The relations and mechanisms that cause these alterations remain to be determined
Research on the heat transfer and internal residual stress of multi-phase systems
Get PDFThe incompatibility of inherent physical properties of the individual constituents often leads to the failures of the whole multi-phase system during the service. We need to investigate the residual stress caused by different inherent properties of the constituents that could finally cause the failure of the whole system and predict the severe time. This paper synthesized a special network-structure composite as the investigated system. The hybrid composites have a honey-comb structure with the high thermal conductivity HfB2 encapsuling the low thermal conductivity B4C. Although the overall thermal conductivity is greatly improved, the different thermal expansivity of the composites can result in a severe residual stress within the composite, which will finally evolve into macroscopy cracks and becomes a threat to the normal operation of the whole system. It is therefore necessary to investigate the magnitude of residual stress and its corresponding distribution. We employed the real-situation modeling and finite element analysis to probe the residual stress caused by the incompatibility of thermal expansivity. This method is effective and has its practical value when applying in relevant industries applications for the prediction and preventing the possible accidents
Mathematical model and motion analysis of a wheeled vibro-impact locomotion system
Get PDFThe paper is aimed at investigating the motion conditions of the wheeled vibro-impact locomotion system equipped with the twin crank-slider excitation mechanism and the additional braking mechanisms allowing only one-way rotation of the wheels. The novelty of the present research consists in the improved mathematical model describing the motion conditions of the vibro-impact system and the proposed parameters optimization technique that allows for maximizing the average translational velocity of the wheeled platform. The main idea of this technique is to provide the maximal velocities of internal bodies when they get in contact with the corresponding impact plates. The numerical modeling results describing the dynamic behavior of the vibro-impact system are obtained in Mathematica software and substantiate the correctness of the developed mathematical model and of the proposed parameters optimization technique. The paper can be of significant practical and scientific interest for researchers and engineers studying and improving the vibratory locomotion systems, e.g., for inspecting and cleaning the pipelines
Numerical modeling of the stress-strain state of the ice beam by specified constitutive model
Get PDFIce cantilever beam is a generic construction component in cold region, referring recent decade research, many reports demonstrated ice mechanic characteristics separately, however, in most previous numerical simulations of ice material are based on the ‘Coulomb-Mohr’ constitutive models. In this article, author also used another ‘user defined constitutive model’ (‘Exponent’ temporary name), which is governed by “nonlinear isotropic harden power law” to simulate the ice cantilever beam mechanic behaviors. As per these numerical results, author made a few comparisons between ‘Coulomb-Mohr’ and ‘user defined’ model, all these compared results contain stress, strain, deformation items in elastic and plastic states respectively, in the meantime, author established series charts, such as ‘stress distributions on failure surface’, ‘dependance of loads with deformations’, ‘dependency of loads and flexural stress with equivalent and plastic strain’, etc., to prove the availability of ‘user defined’ constitutive model. Besides, author proposed some parameter assumptions for further research
The vibration of a thermoelastic nanobeam due to thermo-electrical effect of graphene nano-strip under Green-Naghdi type-II model
Get PDFIn this paper, a new analysis of thermoelastic, homogeneous, and isotropic nanobeams has been constructed in the context of the Green-Naghdi type-II heat conduction law. The first end of the nanobeam is based on a graphene strip, which contains an electrical current with a small voltage which is a novel application. Under simply supported boundary conditions with fixed side ratios, the nanobeam has been thermally loaded with a heat source due to the thermal effect of the electrical current. On the time variable, the Laplace transform technique was utilized to solve the governing differential equations. The solutions were computed in the Laplace transform’s domain. Tzou’s approximation technique based on an iteration formula was used to calculate the Laplace transform inversions numerically. The numerical findings for various values of the electrical voltage and electrical resistivity of the graphene nano-strip have been displayed using graphs illustrating distinct scenarios. All the nanobeam’s researched functionalities have been reported to be influenced by electrical voltage and electrical resistivity. The electrical voltage and resistivity of a graphene nano-strip might be utilized as a tuner to regulate the nanobeam's vibration and energy
Productivity forecast with digital greenhouse automation system for sustainable agriculture
Get PDFGreenhouses are a popular agricultural production method by providing artificial climatic conditions. Providing optimum climatic conditions depends on the equipment of the greenhouse. Greenhouse equipment consists of systems such as heating, ventilation, shading, irrigation, and fertilization. In modern greenhouse cultivation, all these have become controllable with smart systems. These modern greenhouses, in other words smart greenhouses, can read the ambient conditions in real-time with their advanced sensor systems and enable processes such as irrigation, adjustment of ambient temperature, and ventilation to be carried out autonomously. In this study, the working principle, general structure, design, and types of equipment used in the greenhouse automation system are explained, and the system is designed and simulated on the Unity Engine
Utilization of low-potential secondary energy resources at oil pumping station
Get PDFThe article considers the sources of low-potential heat at oil pumping station, estimates the amount of heat of technological processes that is irretrievably lost in the environment from the oil ACD, cooling systems of electric motors and wastewater treatment plants, and also presents possible ways of utilization and useful use of this heat using heat pumps
Improved algorithm for a system with different stiffness for positive and negative displacements
Get PDFIn the process of investigation of dynamics of elements of robots, systems with different values of stiffness for positive and negative displacements play an important role. This change of the value of stiffness has an effect to the results of numerical calculation of dynamics of the system. For more precise investigation of dynamics a special numerical procedure is proposed in the paper. Numerical results for two values of time steps: large and medium ones, are presented for two cases: without application of the proposed procedure and with application of it. Comparison of the presented results indicates advantages of the proposed numerical procedure