Robotic Systems and Applications
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Motion characteristics and energy efficiency of potential energy recycling system of telescopic handler
Get PDFTelescopic handler is combined of truck crane and forklift. Equipped with different accessories, the telescopic handler can achieve fork loading, lifting and other operations. Large amount of energy is needed to maintain lifting and lowering in large range with high frequency of the working device of telescopic handler. There is no energy recycling device for the working device that leads to the large dissipating of gravitational potential energy. In order to recycle the wasted energy, a three-chamber hydraulic cylinder boom system (TCCBS) is proposed. In this paper, the recycling principle is described. Then the energy consumption characteristics are analyzed. Further, the mode of TCCBS of telescopic handler is established and analyzed. Compared with the double chamber cylinder boom system (DCCBS), the single-action time of the boom is reduced 4.15 s. The velocity shock decrease from 0.12 m/s to 0.02 m/s at the beginning of the boom lowering process. The peak pressure decreased from 24 MPa to 21 MPa and the average pressure decreased from 17 MPa to 13 MPa during boom lifting process. The potential energy recycling of the working device is 139 kJ, which accounts for about 47.1 % of total potential energy. The cumulative output energy of TCCBS is 311 kJ, which is 92 kJ less than the DCCBS. The comprehensive energy saving efficiency is 22.3 %. The results show that the TCCBS can realize the potential energy recycling
A study of numerical simulation on extreme flexural stress of ice plate
Get PDFIce plate is general construction component in the cold region and the flexural stress governs its failure pattern. As per the stress equations which were proposed by Westgaard and Masterson, they explained the generic empirical methods to evaluate the extreme and effective flexural stress of ice plate. Based on these equations, most of consequent experiments and simulations referred them directly. Despite of this, there are not any demonstrations about the limitations of these equations by numerical modeling, therefore, it is possible to find the differences between the simulation values and theoretical calculation values by the deployment of numerical simulations from ‘Finite Element Analysis’ perspective, and based on these comparisons, author proposed some assumptions about the limitations of these equations. In the meantime, the simulation process can enhance the understanding of the applications of these equations
Structural mechanics analysis of bolt joint of rigid flexible coupling manipulator
Get PDFAs the key connecting part of the rigid flexible coupling manipulator, the structural dynamic characteristics of the bolted joint are analyzed by using the joint simulation technology of pro/e and ANSYS. Based on the spring equivalent principle, the finite element equivalent model of bolt joint is established, the relationship equation between contact surface pressure and bolt preload is derived, and its stress state is analyzed; Based on the micro convex deformation model and Hertz contact theory, the tangential stiffness equation and normal stiffness equation of the bolted joint are derived respectively. The three-dimensional model of the bolted joint is established by using pro/e and imported into ANSYS for joint simulation. The simulation experiments reveal the influence of bolt joint vibration characteristics under different conditions from the aspects of bolt diameter, pre tightening force, bolt group number and bolt distribution. The conclusions have important engineering value for the structural optimization of rigid flexible coupling manipulator
A convolutional neural network method based on Adam optimizer with power-exponential learning rate for bearing fault diagnosis
Get PDFThe extraction of early fault features from time-series data is very crucial for convolutional neural networks (CNNs) in bearing fault diagnosis. To address this problem, a CNN framework based on identity mapping and Adam optimizer is presented for learning temporal dependencies and extracting fault features. The introduction of four identity mappings allows the deep layers to directly learn the data from the shallow layers, which alleviates the gradient disappearance problem caused by the increase of network depth. A new Adam optimizer with power-exponential learning rate is proposed to control the iteration direction and step size of CNN method, which solves the problems of local minima, overshoot or oscillation caused by the fixed values of the learning rates during the updating of network parameters. Compared to existed methods, the identification accuracy of the proposed method outperformed that of other methods for bearing fault diagnosis
Service performance evaluation of long-span cable-stayed bridge based on health monitoring data
Get PDFService performance evaluation is of great significance to the safety, durability, and reliability of bridge engineering. Over the last decade, structural health monitoring (SHM) systems have been widely used for condition monitoring of cable-stayed bridges, massive monitoring data are measured and stored by the sensing subsystems, which provides the basis for service performance evaluation of bridge engineering. Meanwhile, the load test is a common method to assess the construction and service performance of bridges. Combined the SHM systems and a load test of a thousand-meter level cable-stayed bridge after ten years of service, this paper investigates the operating conditions of main structures, including bridge towers, main girders, and steel cables. 52 trucks were used to conduct a quasi-static load on three key sections of bridges. Meanwhile, the GPS displacement of towers and main girders, stress of the main girders and acceleration responses of cables were measured synchronously by the SHM systems. Based on the health monitoring data, the dynamic responses, structural deformation, and cable tension of the bridge were investigated and evaluated by comparing with the finite element (FE) model load test at construction stage. The results show that the service performance of the bridge is basically within the designed conditions
Modern biophysical view of electromagnetic processes of the phenomenon of life of living biological systems as a promising basis for the development of complex medicine: the role of cell membranes
Get PDFThe results of a theoretical study of the role of cell membranes in electromagnetic generation and in the process of realizing the phenomenon of life are presented in the article. The aim of the theoretical study was to summarize the existing scientific physical and biological knowledge of modern science about the electromagnetic processes of the phenomenon of life at the cellular level in order to deepen the fundamental knowledge of complex medicine. This study is a fragment of research work on “The development of algorithms and technologies for implementing a Healthy Lifestyle in patients with Noncommunicable Diseases based on the study of functional status” (state registration number 0121U108237: UDC 613 616-056-06: 616.1/9-03). General scientific methods and theoretical methods were used in this theoretical study. The main conclusions of the theoretical study were made as follows: 1) Cell membranes can be considered one of the main morphological structures of electromagnetic generation at the cellular level. 2) Cell viability is ensured by electromagnetic generation and electromagnetic generation of cells can be considered as a separate important function of membranes in addition to those already defined, as it provides signaling. 3) The end result of electromagnetic generation of cell membranes and all molecules of the cell is its own electromagnetic fields, which have a millimeter wavelength range with a frequency of 1010-1011 Hz and they are a quantum mechanical result of electromagnetic generations, perform the information-energy function in intercellular interaction in vivo
Socio-political development of CC(U)S in the Baltic Sea region
Get PDFAccording to EU goals and the Paris Agreement, an urgent need exists to reduce CO2 emissions while still securing energy supply. Thus, the timely deployment of carbon capture and storage (CCS) is seemingly unavoidable, especially for the cement and steel industries. However, diverse perceptions of CCS among stakeholders such as experts, politicians, and laypeople exist that could hinder the deployment of the technology, not least in the Baltic Sea Region (BSR). Hence, this research discusses these diverse perceptions and their roots. Furthermore, when it comes to political developments of CCS, after the unprovoked Russian invasion of Ukraine, the whole process of the energy transition in the region is under shadow for the seemingly mid-term while the approach to the energy security and security of supply needs to be revisited. In other words, the countries of the BSR need to manage the energy crisis in the region while following their plans for decarbonisation. In this light, CCS is, therefore, an option to secure energy supply from undesired alternatives like fossil fuels for the short-term and also biomass while curbing CO2 emissions. In sum, this research also discusses the role of CCS in energy security and security of supply concerning the Russian invasion of Ukraine
Dynamic stiffness and vibration analysis model of angular contact ball bearing considering vibration and friction state variation
Get PDFForce and thermal effect are dominant in giving rise to variation of bearing dynamic stiffness and vibration. On the basis of test and theoretical analysis, the dynamic stiffness and vibration model of angle contact ball bearing considering vibration and friction state variation is established. Firstly, based on the quasi-statics of bearing and hydrodynamic lubrication theory, the motion and force relation between each parts are determined by considering the force and thermal effect. Secondly, the friction power consumption of bearing is calculated adopting integrated method, besides, the conduction heat resistance and convection heat resistance in the bearing system are achieved. A steady-state temperature calculation model of angle contact ball bearing-shaft-house system is built based on thermal network method. Finally, the dynamic stiffness and vibration model of angular contact ball bearing including the thermal-solid coupling effect is obtained, which is employed to realize the theoretical analysis of bearing dynamic stiffness and vibration, its accuracy is verified through typical test results. The calculation results shows that there is a good agreement between house test temperature and calculation temperature. The evolution rule of contact deformation and contact stiffness between ball and outer/inner ring over the whole life under excessive preload is the same. So does the oil film thickness and oil film stiffness. However, the curve shape and amplitude of contact angular between ball and outer/inner ring over the whole life is different. Bearing radial stiffness value has a more significant change than axial stiffness value, both of them represent an overall upward tendency. The radial clearance holds a negative correlation with house temperature, however, the radial displacement has a positive correlation with house temperature. The evolvement curve of contact angular affected by various preload and speed is opposite. The contact load between ball and outer/inner ring has the same trend influenced by preload and speed with EHL. The variation of preload has bigger effect on temperature rise than speed change. The oil film has little influence on contact angular, contact load and temperature under dry-lubricated or lightly lubricated condition
Influence of floating support on the dynamic characteristics of compound planetary gear set
Get PDFDue to a large number of components, complex meshing relations and high requirements for assembly accuracy, the dynamic characteristic of compound planetary gear, such as vibration, impact, periodic motion and load sharing, are more easily affected by internal excitation than those of simple planetary gear set and parallel shafting gear set. To improve the load sharing behavior and the resistance of Chaos motions in the compound planetary gear set, in this work, by introducing the floating support into the center gear and planet gear, a lumped-parameter dynamic model of the compound planetary gear set is built based on the lumped parameter method and Lagrange kinematics equation. The steady response is calculated by numeric method to investigate the influence of floating support from different components on loading sharing behavior and periodic motion. The results indicate that, the increase of the floating value of all components improves the instantaneous load-sharing behavior, and single floating of planet gear reduces the load sharing behavior. To avoid the system being in quasi-periodic motion and Chaos motions under the condition of floating support, the input speed should be avoided away from the range of 3201 r/min-5069 r/min
The longitudinal vibration characteristics and parametric analysis of a ship thrust bearing integrated with internal disc springs
Get PDFTo reduce the transmission of shafting longitudinal vibration in surface ships, a design of thrust bearing integrated with internal disc springs is proposed and the longitudinal vibration characteristics of the shafting are studied. According to the structural characteristics of thrust bearing and the deformation characteristics of disc springs, the specific size and combination forms of disc springs in the thrust bearing are designed, and the effective disc springs schemes are achieved according to the static and dynamic design requirements. With the integration of the disc springs into the thrust bearing, the peak of longitudinal displacement response at the base of thrust bearing can be reduced by 10 dB by two schemes of disc springs. The proposed design can effectively suppress the transmission of shaft longitudinal vibration to the hull, which has engineering significance for the longitudinal vibration control of the shafting of the surface ship