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Research on dynamic characteristics of marine engine transmission system
Get PDFAs the main component of marine engine, the transmission system often produces serious vibration and noise, which will significantly affect the performance and service life of the driving mechanism. In order to provide reasonable structural design basis for marine engine transmission system, the dynamic characteristics under different working conditions were studied in this paper. A simplified rectangular structure was applied to express the instantaneous motion state model of the chain link, and the equation was expressed according to Euler kinematics theory. The MNF (modal neutral file) model was derived by making the links and pins flexible parts, and the rigid flexible coupling model of the transmission system was established based on ADAMS. Since invalid constraints were adjusted and replaced, the transmission system model could be simulated and calculated precisely under the conditions of different tension, spindle rotation speed and driving sprocket teeth number. By changing the model parameters through the single variable method, the variation rules of transmission ratio, spindle radial force, transmission ratio deviation and maximum transient stress of chain link were obtained respectively. According to the design and construction of vibration test platform, the simulation result was verified, and the spectrum response results of the chain drive system were obtained. The results show that the rigid flexible coupling model can achieve high simulation accuracy in the chain drive system. Reasonable tension and sprocket teeth number can not only reduce the amplitude, but also reduce the fluctuation of output torque and transmission ratio
Fault logic circuit design of switching power supply based on soft reference circuit module
Get PDFThe basic idea of the circuit fault diagnosis method based on fault logic is to establish a computer expert database system first, connect the computer to the GPIB interface card, and then connect each intelligent instrument through the GPIB standard bus. Through the connection of the tested object adapter and the tested object, a circuit fault expert diagnosis and test platform are formed. Based on the traditional fault simulation model, this paper improves the fault logic circuit of switching power supply, designs the system model of fault simulation, deals with the logic structure and circuit hierarchy respectively, and produces the final output through the logic gate circuit by comparing the results of the fault logic circuit and the fault-free logic circuit. The designed switching power supply fault logic circuit works in the switching state, which has the characteristics of low loss and high energy conversion efficiency. Through the simulation analysis, the output is connected to the comparator, which plays the role of the whole wave. The simulation results are in line with the parameter indicators. The functional test results of the chip show that the function of the module is basically normal, which has practical application value and good portability and can be used as a reference for similar electrical designs
Influence of landform on the pressure distribution of explosion shock wave
Get PDFThe explosion site terrain and geomorphic environment will directly affect the shock wave pressure propagation and attenuation law and the shock wave test results uncertainty evaluation. In this study, the explosion site topographic and geomorphic parameters were analyzed, and the slope ratio and elevation difference within the region were proposed to parameterize the test site topographic and geomorphic characteristics. Using multi-physical field coupling simulation software, the finite element numerical simulation model of acoustic-solid structure coupling with different elevation difference and slope ratio is established and relevant research is carried out. The results show that when the pressure monitoring point is located at the test site low position, the elevation difference plays a role in attenuation of the shock wave pressure peak value, and vice versa; With the increase of the test site slope ratio, the shock wave pressure peak value at different test points gradually increases, and with the increase of the distance between the test points, the impact degree gradually decreases. Therefore, the elevation difference and slope ratio of the site shall be reduced as much as possible during the explosion shock wave pressure test, so as to improve the shock wave pressure test accuracy and the test data reliability, and provide theoretical support for the shock wave pressure test results uncertainty evaluation in the explosion field
Vibration influence of different types of heavy-duty trucks on road surface damage
Get PDFUnder the interaction of the wheels of heavy-duty trucks on the random road surface when the vehicles are travelling, their generated vibrations not only affect the driver's ride comfort but also impact the road surface damage. To assess the vibration influence of different types of vehicles on the road surface damage, three dynamic models of the two axle, three axle, and four axle of heavy trucks have been build and computed via the Matlab/Simulink software. The dynamic tire load, dynamic load coefficient, and dynamic load-stress factor are chosen to assess the friendly load of different heavy trucks under the different operating conditions of the vehicle. The obtained result indicates that the dynamics parameters including suspension system, tires, and axle load distributions of heavy trucks have a greater effect on the dynamic tire force than the total weight of the vehicle. In order to ensure the road’s safety, the traffic management should intervene quickly to give a velocity limit for vehicles under the condition of the vehicle moving with the empty loaded on the poor road surface
An overview of Baltic Carbon Forum conference 2022
Get PDFBaltic Carbon Forum (BCF) is an annual event sponsored by Nordic Council of Ministers through Nordic Energy Research through their network BASRECCS. BCF 2022 was held on 13th and 14th Oct. in Kaunas, Lithuania. The aim of the BCF 2022 was to enable interested and engaged stakeholders to meet, discuss, share knowledge and experiences, and develop projects. BCF also aims to increase awareness about Carbon Capture Utilization and Storage (CCUS) among younger generations with aim of securing a sustainable future for all. The BCF2022 invited a number of academic and industry experts from the Baltic Sea region countries, which included policymakers, financial institutes, industry representatives and academics for sharing their experiences, conduct discussions and brainstorming sessions to identify gaps with aim of expediting the deployment of a large-scale CC(U)S project in the Baltic Sea Region (BSR). BCF 2022 was attended by 74 participants. There were 38 participants who attended the conference onsite and 36 participants attended the conference online. Participants came form 15 countries, which included Finland, Lithuania, Hungary, Sweden, Poland, Norway, Estonia, Denmark, Latvia, Belgium, Germany, USA, UK, India and South Africa. This paper presents a short summary of all the talks presented at the BCF 2022 conference [1, 2]
Vibration-collision mechanism of dual-stabilizer bottom hole assembly system in vertical wellbore trajectory
Get PDFThe lateral vibration of drill string causes well deviation and the collision between drill collar and sidewall, and severe lateral vibration even affects the drilling safety or reliability. In view of the problems above, the lateral vibration characteristics of drill string need to be analyzed. Therefore, a newly vibration-collision model of BHA (bottom hole assembly) with random collision characteristics is proposed in this paper. Firstly, the dynamic model of drill collar with double stabilizer is presented by utilizing the Lagrange equations. Secondly, the dynamic characteristics of drill collar in air and mud drilling is analyzed with different collision frequencies. Subsequently, the displacement and motion trajectory of drill collar under different structure parameters of BHA and mechanical parameters of system are investigated by numerical simulation. Finally, the influence of rotation speed of BHA and length of drill collar on lateral vibration of drill collar is discussed. The results indicate that the lateral vibration of drill collar in air drilling is more serious than that in mud drilling; and the higher the collision frequency, the more severe the lateral vibration. Improving rotation speed of BHA, length of drill collar and WOB (weight on bit) have promoting influence on lateral vibration of drill collar; however, increasing stabilizer diameter has suppressing influence on lateral vibration of drill collar. The research findings give reasonable guidance for structure design of BHA and selection of mechanical parameters of system
Nonlinear dynamic analysis of power reflux hydraulic transmission system
Get PDFPower reflux hydraulic transmission system (PRHTS), which is a recently introduced continuously variable transmission system, enables the improvement of fuel economy of construction vehicles. For investigating the nonlinear dynamic characteristics of PRHTS, its nonlinear dynamic model is established by merging the dynamic models of a planetary gear train and torque converter. A dynamical model of the planetary gear train reveals the parameters of mesh damping, time-varying mesh stiffness, and transmission error. The nonlinear dynamic equations of the PRHTS are solved using the fourth-order Runge-Kutta method. The dynamic orbits of the system are observed through bifurcation diagrams, which use the internal excitation frequency and meshing damping ratios, both of which are dimensionless, as control parameters. Numerical examples show the dynamic evolution mechanism involving one-period motion, multi-periodic motion, quasi-periodic motion, and chaotic motion. The onset of chaotic motion is identified from bifurcation diagrams, dynamic trajectories, phase plane diagram, and Poincaré maps of the PRHTS. The simulation results provide an understanding of the operating conditions under which undesirable dynamic motion occurs in PRHTS and serve as invaluable information for effective dynamic design of PRHTS
Lower canine traction with jaw functional orthopedics. case report
Get PDFThe treatment of impacted teeth requires an interdisciplinary approach, in which early diagnosis avoids later complications. The frequency of canine retention, especially of the lower canines, has a 0.22 % average in the general population. Case information: A 9.1-year-old patient presented Lepto/Lepto, Lepto; distocclusion due to retrognathism and maxillary protrusion with left condylar asymmetry and preferential chewing on the right side. The patient also presented a structural open bite (Lower Go 78°) hyper-divergence level 4; severe crowding with complete lack of space for tooth 33, and alteration of the eruption corridor of tooth 43. Objective: Stimulate jaw growth to correct distocclusion, stimulate transversal development to gain space and eliminate crowding, and exercise traction on the lower right canine to position it correctly and correct asymmetry. Methods: A series of functional orthopedics devices were used. A Standard Bimler during the first 6 months, subsequently, Simões Network 1 (SN1) to conquer space and initiate traction, followed by the use of an SN11 to correct asymmetry with contra attachment for de-rotation and a lingual S spring. Results: It was possible to obtain incisive contact and align the anteroinferior segment, full space was obtained for tooth 33. Traction of tooth 43 was achieved and thus asymmetry was controlled. Conclusions: Functional orthopedic techniques are an effective form of dental traction that favors treatment from different perspectives. On one hand, it allows to gain space to eliminate crowding. On the other hand, it does not affect neighboring or antagonist teeth because the anchorage is not on the teeth, and it is not necessary to place intraosseous mini-implants. Also, an adequate surgical and functional orthopedic procedure makes it possible to traction the impacted teeth, orienting them to erupt and occupy the correct position in the dental arch
Trajectory planning and control algorithm of industrial robot manipulator
Get PDFAs the industrial robot task becomes more complex, the difficulty of trajectory planning and tracking control of manipulator is gradually increasing. To minimize the vibration during the manipulator motion and improve the planning accuracy, the method of quintic polynomial combined with non-uniform B-spline interpolation is studied for joint space (JS) planning. The trajectory tracking system is easily affected by friction nonlinearity and parameters. So a JS trajectory tracking controller based on based on fuzzy neural network (FNN) is designed. Through simulation experiments, the curve obtained by the planning method studied is smoother and the planning error is minimum. The maximum position error is 0.09 rad, and the speed error is not more than 0.1 rad/s. The controller performance test results under different parameters show that the W^, c^, κ^ parameter in FNN can be adjusted in real time, and the value will not affect the performance of the controller. The fluctuation range of trajectory error of different joints is within ±0.2×10-5rad, which indicates that the performance of AFNNC controller studied is better. And its response time is the shortest and its robustness is better when the load changes suddenly
Stakeholder dynamics and their impact on value creation for industrial maintenance projects-a literature review
Get PDFThis paper analyses research developments in the dynamics of stakeholders and their impact mechanisms on the creation of value through a literature review. Three databases, Scopus, Science Direct and Google Scholar are selected to search articles. This study employs a quantitative descriptive analysis and a qualitative thematic analysis to provide a perspective of the data. The findings of the review reveal that stakeholder dynamics management is embedded in project environments and that the dynamic nature of the stakeholder salience attributes can be classified under stakeholder influence and engagement, project lifecycle and dynamics, value creation and framing, and project and stakeholder-associated risk. However, from the characterisation and the drivers of stakeholder dynamics discussed in the literature, the perspective of project risk dynamics has been understudied, with a focus mainly on stakeholder-associated risk to the project, and less on project risk and the stakeholder interactions related to potential losses or gains by stakeholders from such project decisions and activities. Although there is a recognition of the importance of managing stakeholder dynamics within project environments, the factors that affect stakeholder dynamics and their impact on the creation of value for industrial maintenance projects are still unclear. The outcome of the literature review can assist in providing the foundation for the authors’ empirical work of developing a novel conceptual framework for analysing stakeholder dynamics and their impact on maximising value creation in the context of industrial maintenance projects