JVE International
Not a member yet
1200 research outputs found
Sort by
Effect of dynamic regime of rollers of pocket folding machine to quality of printing products
Get PDFMeasurements of dynamics of rollers and their segments in the direction of transverse axis of rotation of eight cassettes of folding machines were carried out in this work. Measurements were carried out in pre-selected positions of rollers and their segments for two different rotating velocities of the rollers. In the first case the roller was rotated at 9 m/min velocity and in the second – at 90 m/min. It was determined that before renewal some rotating rollers for the investigated velocity of rotation of the roller 90 m/min experienced the displacements up to 80 μm. The displacements (beatings) of the rollers and their segments originating during the process of rotation in the direction of transverse axis of rotation have substantial effect to the quality of folding of printing products. Numerical investigation of the rollers was performed by using the axisymmetric model. Supplementary stiffness from the static loading caused by centrifugal forces is taken into account. The eigenmodes are calculated. The standing waves on the surface of the roller are investigated
An experimental methodology for evaluating the energy cost and comfort during cycling: a case study for analyzing tire pressure influence
Get PDFMultiple parameters affect energy cost and comfort during cycling, and for some of them there is a trade-off between both phenomena. The aim of this paper is to present a methodology to evaluate the influence of different cycling conditions on energy cost and cyclist’s comfort. The proposed methodology is based on on-road tests where power on pedals and vertical accelerations are measured. The experimental data is used to calculate energy cost and comfort indices to compare different cycling conditions. A case study of the tire pressure influence on energy cost and comfort is presented
Correction of max-min approach for analyzing shock response of strongly nonlinear system
Get PDFA novel method combining max-min approach (MMA) with energy method is proposed for the derivation of the approximate analytical solution for shock response of the strong nonlinear system. MMA is used to evaluate the governing differential equation with nonlinearity terms and to obtain the approximate solution. The maximum shock response displacement of the system is obtained by energy method, and then the approximation solution by MMA is corrected. Three examples are given to illustrate the validity of the method. It is shown that the corrected MMA method always lead to a better approximate solution for different kinds of nonlinear problems. The results provides a new simple but effective method for the analysis of shock response of strong nonlinear problems
A method for analyzing sensitivity of multi-stage planetary gear coupled modes to modal parameters
Get PDFThis paper proposes a method of analyzing distinct modal characteristics to obtain accurate sensitivity of natural frequencies and coupled modes to system parameters of multi-stage planetary gears. A purely rotational dynamic model of multi-stage planetary gear system with general descriptions is established based on the lumped mass method. The vibration modes of multi-stage planetary gears are classified into overall and planet modes with unique properties. According to the modal energy distributions in multi-stage planetary gears, the natural frequencies are clustered by each dominant vibration stage. The modal properties of each cluster in the multi-stage planetary system are similar to the single-stage planetary gear system established by the associated dominant vibration stage. It is shown that, variation of gear parameters in one planet stage mainly affects the natural frequencies in the cluster associated with the same stage, while the coupling shaft parameters significantly impact the natural frequencies corresponding to the planet stage which contains the connected sun gear
Optimum design of printed electronics inkjet printer using response surface model and multi-objective genetic algorithm
Get PDFThe purpose of this project is to improve the optimization design of complex mechanical structure based on the combination of response surface model and multi-objective genetic algorithm (MOGA). First of all, we built the finite element model (FEM) for the printed electronics inkjet printer through experimental modal analysis (EMA) and finite element analysis (FEA). The analysis of the static and dynamic characteristics of the FEM confirms the weak points of the structure and its actual performance. Next, using central composite design (CCD) method, it selects sample points in the design space and carries out numerical simulation and establishes the initial second order response surface model with eight design variables to further determine the inkjet printer’s first order natural frequency, weight and maximum deformation of the inkjet head. Finally, it carries out an approximation optimization of response surface model using MOGA to obtain the Pareto optimal solution set. Our simulation results determine that the optimal solution can increase the first order natural frequency of the inkjet printer by 36.3 % to effectively avoid the resonance region caused by the servo motor excitation. The maximum deformation of inkjet head decreases by 33 % and the weight of the inkjet printer can be reduced by 19.5 %. We believe that optimization can improve the performance of the inkjet printer and reduce its weight at the same time. The method proposed in this study is suitable for multi-objective optimization of complex structures similar to the printed electronics inkjet printer
Seismic signal segmentation procedure using time-frequency decomposition and statistical modelling
Get PDFIn the paper a novel automatic seismic signal segmentation procedure is proposed. This procedure is motivated by analysis of real seismic vibration signals acquired in an underground mine. During regular mining activities in the underground mine one can expect some seismic events which appear just after the mining activity, e.g. blasting procedures, provoked relaxation of rock and some events that are unexpected, like natural rock burst. It often happens that, during one signal realization, several shocks (events) appear. Apart from two main sources of events (i.e. rock burst and blasting), other activities in the mine might also initiate seismic signal recording procedure (for example machine moving nearby the sensor). Obviously, significance of each type of recorded signal is very different, its shape in time domain, energy and frequency structure (i.e. spectrum of the signal) are different. In order to recognize these events automatically, recorded observation should be pre-processed in order to isolate a single event. The problem of signal segmentation is investigated in literature, several application domains might be found. Although, there are just a few works on seismic signal segmentation. In this paper we propose to use a time-frequency decomposition of the signal and model each sub-signal at every frequency bin using statistical methods. Narrowband components are much easier to search for so called structural breakpoint, i.e. time instance when properties of signal significantly change. It is obvious that simple energy-based methods applied to raw signal fail when one event begins before the previous one relaxed. In order to find beginning and end of a single event we propose to use measures based on empirical quantiles estimated for each sub-signal and, finally, aggregate 2D array into 1D probability vector which indicates location where statistical features has switched from one regime to another one. The proposed procedure can be applied in order to improve time domain isolation of single event for the case, when duration of signal acquisition is longer than duration of the event or to isolate single event from sequence of events (recorded for example during blasting)
Control measures about vibration and noise of pipeline onboard marine vessels
Get PDFThe pipeline noise is an important part of the sources of vibration and noise for high performance marine vessels. It is vital to control the vibration and noise of the onboard pipeline to improve the acoustic stealth and life level in marine vessels. The vibration and noise caused by the onboard pipeline system was analyzed. Some methods and advices were put forwards to reduce the vibration and noise caused by the pipeline system, including the control of vibration, structural noise and fluid noise. In addition, a new concept “pressure-stabilized bladder” was created
Dynamic analysis in a micro drilling process with ultrasonic vibration
Get PDFIn recent years, the processing technology of advanced machinery has toward precision, high-performance, and high-speed. Therefore micro-fabrication becomes more important such as the getting smaller aperture in the printed circuit board (PCB), it tends to be more severe due to vibration. The vibration has adverse effects to machining accuracy and surface roughness which will increase tool abrasion and further accelerate the destruction from material fatigue. There are many ways to produce perforations, such as laser micro-machining and micro-drilling. The industry still adopts micro drill piercing process due to the cost and technical considerations. In order to enhance the cutlery life and the quality of the drilling process, the cutting characteristic of bur is important. Hence, the vibration during drilling must be suppressed. This study is to investigate the dynamic analysis of a micro drill under ultrasonic vibration (50 kHz) excited with a piezoelectric-driven actuator experimentally and numerically by using finite element analysis. The results show that the vibration and the cutting forces are effectively reduced and thereby the cutting performance is improved when introduces ultrasonic vibrations during micro-drilling process
Coupled vibration of a concrete pipe pile with saturated soil due to longitudinal loading
Get PDFThis paper considers the longitudinal coupled vibration of an elastic bearing concrete pipe pile with the saturated soil. The outer and inner saturated soil are governed by the dynamic consolidation theory originally presented by Biot. The governing equations of soil are transferred to ordinary differential equations by Laplace transform. The volumetric strain and pore pressure of soil are obtained by directly solving the coupling equations of soil without introducing potential functions. The analytical expressions of the displacements and shear stresses of the soil are then obtained. The pile response is derived on the basis of 1D elastic theory and the perfect contacts between the pile and soils. The displacement and velocity of the pile in time domain are obtained by using numerical inverse transformation. Selected numerical results are presented to portray the influence of the existences of soils, pile geometry and dynamic permeability coefficients of soils on the vibration characteristics of the pipe pile. At last, the displacement response between a pipe pile and solid pile are compared
Investigation of electrical conductivity of milk in robotic milking system and its relationship with milk somatic cell count and other quality traits
Get PDFThe scientific research was carried out at Lithuanian University of Health Sciences, Veterinary Academy, state enterprise “Pieno tyrimai”, as well as in dairy farms running automatic voluntary (robotic) milking systems in Lithuania. A total data set of 462574 cow milking records was assessed in the research. The objectives of this investigation were to evaluate the milk electrical conductivity indicator from robotic milking system and to assess the genetic correlation with the indices collected in a database of Lithuanian dairy cattle, to estimate heritability coefficient using multiple traits mixed linear model with permanent environment effects. The research has shown, that the electrical conductivity of milk ranged from 4.6 to 5.8 ms/cm in milk samples where somatic cell count did not exceed 200 thousand/ml and variation in electric conductivity of milk can be treated as one of the main parameters for cows’ health monitoring system. A high coefficient of heritability of electrical conductivity of milk (h2 = 0.512 ± 0.028; p < 0.001) and a very low coefficient of heritability of somatic cell count (h2 = 0.032 ± 0.014; p < 0.001) was determined. The results of the research have also revealed a positive genetic correlation of electrical conductivity with milk somatic cell count (rg = 0.332 ± 0.016; p < 0.001). Electrical conductivity of milk from robotic milking system can be introduced as an indicator of mastitis prevention in dairy cows and genetic selection based on this trait may be possible