Journal of Engineering and Thermal Sciences
Not a member yet
1200 research outputs found
Sort by
Dynamic photoplantography examination for tibial torsion measurement
Get PDFIn our work we used glass pedograph with digital camera under pedograph, computer and ultrasonograph. For tibial torsion measurement a patient was standing on the glass pedograph. A luminodiods was settled directly under tips of malleoli. Ankle joint axis passes through tips of malleoli and it was distal reference line. Rectangular ultrasound scanner probe was placed in parallel with posterior margin of the proximal articular surface of the tibia, it was proximal reference line. To avoid optic distortion we placed crus axis in line with optical system axis. Photoplantogramm was captured and estimated. We estimated angle between two reference lines (direct method of tibial torsion measurement). We measured tibial torsion with our method and MRI (5 patients, 10 legs). Tibial torsion measurement by MRI was performed by Schneider method (1997). Mean value of tibial torsion was 290 (our method) and 400 (Schneider method). Pearson correlation coefficient was 0.9. Dynamic photoplantography is cheap, informative, easy method in early pathology revelation. It can be used as screening method among large collectives. Functional photoplantograms help us to estimate foot arch function. Treatment control is very easy to perform with dynamic photoplantograph
Representation of time averaged vibrating images in the operator format
Get PDFThe process of time averaging of greyscale images is expressed in the operator format. It is shown that the inverse problem of the reconstruction of the original image from its time averaged image is an ill-posed problem. Application of time averaging techniques is proposed for cryptographic applications especially when the density function of variable defining the dynamic deflection from the state of equilibrium is arcsine distributio
Vibrations of a double wall plane adaptive to electrorheological materials
Get PDFAn analytical study of vibrations response and control capabilities of an Electrorheological (ER) material-filled double wall plate to random excitation pressure is presented. The governing equations of motion are developed by incorporating the ER material constitutive relations to thin face plate equations. A three-parameter viscoelastic model is used to characterize ER material behaviour in pre-yield regime. The effect of electric field strength on the response of the double wall sandwich plate with ER material is investigated. Numerical results include response spectral densities and modal frequencies for several ER material core thicknesses and different electric field level
Research of microstructure and steadfastness of bioceramic coatings formed by magnetronic method
Get PDFPaper presents the research of microstructure and steadfastness of polyethylene medical implants coated with ceramic and other materials. After 2500 loading cycles it was noticed that the strongest implant ceramic coatings are Co+TiO2 and Co-Cr-Mo. However the roughness of Co-Cr-Mo surface is far larger than Co+TiO2. The largest and the highest collections of granules are formed in the Co-Cr-Mo coating, and the medium -- in Co+TiO2 coating. Consequently, more durable implant coating is Co+TiO2
Research of frequency characteristics of nonlinear biotronic subsystem of muscle
Get PDFPaper presents the research of muscle nonlinear stiffness characteristics dependence on the loading duration. The nonlinear differential equation of nonlinear biotronic subsystem of muscle has been derived. Analyzing mentioned expression by numerical methods it was determined that there are three main dominant frequencies in the frequentative characteristics of the muscle and values of them and amplitudes of oscillations decline as the load time becomes longer. Comparison of analytical research results to experimental ones has shown that their regularities are nearly related
Damage quantification using modal parameters
Get PDFNatural frequencies and mode shapes of a structure change whenever a structure has any kind of damage. However, detection of location and magnitude of damage has always been difficult. This paper presents a technique to locate and quantify the damage when the natural frequencies and mode shapes of undamaged and damaged structure are known. First, the structure is modeled using finite element formulation. Each element is assigned a damage index that is initially zero for undamaged condition. Modal analyses of undamaged and damaged structures are performed. The damage indices are computed using non-negative least squares method. Results based on aluminum beams are presented to establish the effectiveness of this method
Design considerations of a microelectrostatic motor
Get PDFThis work analyses influences of geometry of the micromotor on its performance. Using finite element modeling (FEM) a detailed study of electrostatic force fields between two interacting poles and developed moment of rotation is done. The results received are expanded to the whole motor design where its control and torque characteristics are evaluated. Finally, optimal motor construction conclusions are drawn and new motor is produced by UV lithograph
The suboptimal set of parameters describing human gait
Get PDFThe influence of choosing a set of parameters describing human gait for automatic gait analysis and assessment has been presented in this paper. The investigations were based on three sets of parameters and two different classificators. The conclusion is that the best set of parameters is set of coefficients which have been obtained by modelling of human gait by means of identification using the regression functio
Research into the heart rate and blood pressure dependence on loading and time
Get PDFThe article deals with the dependence of the effect of physical load on male and female heart rate and blood pressure on the step and constant load with a change in time. It has been established that with the load applied to different male and female age groups and its time increasing, the heart rate and blood pressure increases in terms of non-linear dependence. Characteristic points have been determined to exist in the functional dependence of the heart rate and blood pressure on the time of loading, in which the derivative value of the function is equal to zero. The human fatigue criterion has been established on the basis of the derivative of this characteristic point, which shows the individual’s reserve of the working capacity and its duratio
Chain type system with wave excitation
Get PDFVarious systems based on waves and vibrations are used for displacing, grouping, classification of multidimensional media and bodies. This paper deals with such wave operation based systems augmented by self-stopping elements which ensure one-directional motion of the driven sub-systems. Such enhancements can improve some dynamical characteristics of the analysed systems. The objective of this paper is to develop models of systems and methods of analysis which would help to reveal nonlinear dynamical properties and phenomena of those systems. The conditions of solutions' existence and stability, basin boundaries are determined. Simpler cases are analysed analytically. The obtained relationships provide insight into nonlinear dynamics of complex systems which are analysed numerically