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Stability enhancement method and experiment of orchard vehicle control
Get PDFStudy on orchard working vehicle rollover and tipping prediction is important to maintain vehicle stability control in complicated operation conditions of orchard. Existing rollover and tipping prediction models for vehicles can not directly apply to orchard working vehicle, which structure and loading are changing under operation. So it is necessary to move ahead study on orchard vehicle bodywork posture prediction and rollover and tipping prediction by theoretical analysis, mathematical modelling, real vehicle test and other methods. In this paper, firstly, we establish orchard working vehicle dynamic model, analyses variation of key parameters during vehicle instability state, and look for characteristic parameters of vehicle instability. Secondly, active safety control algorithm which based on posture detection of vehicle body is researched. Finally, control model is verified and optimized by scaled test
Equilibrium forms branching of a nanolayers system
Get PDFIn this work we analyze equilibrium forms branching of three parallel conductive micro/nanolayers which can be used as a sensor of internal or external mechanical and electrical parameters such as conductivity, tension force or gap between layers. Alteration of physical parameters can lead to symmetry breaking, i.e. asymmetrical deflection of outermost layers and nonzero deflection of middle, initially neutral layer. By slow current intensity variation in one of outermost layers, initial symmetry of the system can be achieved, thus determining the parameters alteration which had occurred
Cognitive design of products for engineering and vibromechanics by criterion of minimization labor input of their manufacturing
Get PDFThe basis of the algorithm for determining the labor input are user-configured according to the parameters of its real production. It is shown that in the early stages of designing the designer can minimize the expected cost of the product by changing the design solutions, its head by a reporting engine will evaluate the range of materials and assortments and will issue guidelines to reduce it, and the technology and setters will calculate the final demand for materials and labor. Developed labor regulation system, built on the theory of fuzzy decision trees
Automatic system for measuring shifts and deformation of dental prostheses
Get PDFThe paper presented a multi-purpose system for testing of dental prostheses within the static and kinematic conditions as well as the conditions of its stability quick analysis. The common goal of prosthetics specialists is to define biomechanical criteria shaping the restorations to protect the existing state of the biological substrate [1]. In prosthesis biomechanics, the gingival soft tissue, as substances with heterogeneous properties, are difficult to individual assessment of the value, direction and duration of the occlusion forces transmitted by the prosthesis in the life cycle [2]. More predictable are static or kinematic behaviors, reflecting the mechanical states of prosthesis design with designed shape and material properties which are possible to determine. However, static measurements of dentures do not reflect their work in natural conditions [3], and can only designate the values of selected parameters (deflection, stress) during the reference of constant load values. The article presents the author’s research stand for kinematic loads testing, which are similar to natural ones during shredding of food. The results of stress and strain of denture prosthesis, identified during laboratory tests, will be used to verify the mathematical models of dentures during kinematic forces
Research on measuring method of the angular displacement of muzzle vibration
Get PDFThe angular displacement of the muzzle vibration has importance influence on the firing dispersion of gun. In order to solve the measuring problem on the angular displacement of the muzzle vibration in firing environment, a kind of measuring method of the angular displacement of the muzzle vibration based on the laser and the triangle principle was presented, and its measuring system was developed. The laser beam was sent by a laser. After the laser beam was reflected by a reflector on muzzle, the reflective beam was received by the position sensitive detector (PSD). Combining the optical distance parameter and the triangle relation, the angular displacement of the muzzle vibration could be obtained. The measuring error analysis of the system and the verification of the firing environment in shooting range were made. The performances of the measuring system were that the measuring range of the angular displacement was ±35', its angle resolution was 0.1', its relative errors under the different illumination conditions were less than 2 %. The measuring system can meet the needs of the gun measurement
3-D finite element analysis on shear lag effect of curved box girder under multi-dimensional seismic excitation
Get PDFShear lag effect of curved box girder under multi-dimensional seismic excitation is studied in this paper. Firstly, spatial finite element model is established based on ANSYS, and a seismic wave, which is recorded in second site, is chosen as ground acceleration time history. Secondly, elastic dynamic time-history analysis focused on shear lag effect is carried out, where 4 working conditions, 3-D seismic, longitudinal-vertical seismic, vertical seismic and transverse seismic only, are considered. Thirdly, critical angle of seismic waves is investigated, it is seen that under seismic excitation, there is a prominent shear lag effect on upper flange at mid-span of the curved box girder, and there are also various shear lag effect modes under the different working conditions of seismic excitation. The shear lag under 3-D seismic is severest, normal stress is concentrated on inside upper flange, then that under longitudinal-vertical seismic is less serious, in which case, the stress is appearing within a regional proximity to the junction between webs and flange, the next is under vertical seismic, and the shear lag effect under transverse seismic is most non-prominent. Finally, the numeric results are compared with the experimental results from a vibration table testing, which shows great consistencies
Determining the vibration behavior of metal matrix composite used in aerospace industry by FEM
Get PDFAA2124/SiC/25p material is metal matrix composites (MMCs) reinforced with particles and homogeneous distribution, which are used especially in the aerospace industry. Vibrations of the material was evaluated by the finite element analysis (FEM). First, it analyzed as a plate 130×50×3 mm the natural frequency of the material was found in the 0-5000 Hz range. Also frequency modes of the material were determined. In order to determine the reaction against the load material, the point has implemented and forced damped vibrations. Finally, the reaction spread by forced vibration damping materials was examined
Noise subspaces subtraction in SVD based on the difference of variance values
Get PDFAs a matrix decomposition method, Singular Value Decomposition (SVD) is introduced to signal processing such as denoising. Firstly, a polluted signal is constructed in Hankel matrix form, and then through SVD the Hankel matrix is decomposed to two unitary matrices and a diagonal matrix in which a series of singular values are arranged in a descending order. These singular values are considered to be located in a series of subspaces including signal subspaces and noise subspaces. The singular values in these subspaces are different because the signal magnitudes dominate noise magnitudes. Therefore, if these two kinds of subspaces are well separated, an ideal denoised signal could be achieved by reconstruction. This paper improves the traditional SVD denoising which merely does well in processing periodic signals’ subspaces separation. The improved SVD denoising method based on variance value extends SVD denoising to aperiodic signal denoising. The denoising results by improved SVD denoising, traditional SVD denoising, wavelet thresholding and EEMD denoising are compared and the improved SVD denoising method received an excellent numerical experimental effects
Stability and slow-fast oscillation in fractional-order Belousov-Zhabotinsky reaction with two time scales
Get PDFThe fractional-order Belousov-Zhabotinsky (BZ) reaction with different time scales is investigated in this paper. Based on the stability theory of fractional-order differential equation, the critical condition of Hopf bifurcation with two parameters in fractional-order BZ reaction is discussed. By comparison of the fractional-order and integer-order systems, it is found that they will behave in different stabilities under some parameter intervals, and the parameter intervals may become larger with the variation of fractional order. Furthermore, slow-fast effect is firstly studied in fractional-order BZ reaction with two time scales coupled, and the Fold/Fold type slow-fast oscillation with jumping behavior is found, whose generation mechanism is explained by using the slow-fast dynamical analysis method. The influences of different fractional orders on the slow-fast oscillation behavior as well as the internal mechanism are both analyzed
Influence of motor control characteristics on load sharing behavior of torque coupling gear set
Get PDFThe influence of the control characteristics of a direct torque control (DTC) motor on the load sharing behavior of a torque coupling gear set is studied by establishing a dynamic model of a multi-motor torque coupling system. The effects of run-out errors of the pinions of the torque coupling gear set on the powertrain are analyzed under steady operating conditions. The difference in rotational speed among the pinions becomes apparent, and the load sharing behavior deteriorates when there are run-out errors. The relationship between the control characteristics and load sharing behavior is studied. The difference in rotational speed decreases and the load sharing behavior improves as proportional and integral gains of the speed controller increase