Numerical methods for determining local motions of human knee joint

The Biomechanical Team of the Szent István University has been carrying on a comprehensive project of the human knee joint. The conception is oriented to the local motions and the phenomenon (and its influence) of wear. By establishing different experimental models, in order to verify and universalize the results, numerical models must be devel-oped and applied. This paper presents our numerical method on biomechanical- and simple engineering application

Csúszva gördülés értelmezése térdízület biomechanikai vizsgálatához

This paper represents a new and unique method about the determination of the proportion of sliding and rolling. This new methods was achieved in order to carry out biomechanical examinations, more precisely, to study the connecting surfaces of the condyles. Intrinsically the sliding attribute of the condyles will be examined, exceeding the well-known limit of pure sliding and rolling, introducing and applying the calculation method on a practical example

Biomechanical research of Szent István university

This paper represents a short summary of the human knee joint modeling. The Biomechanical Team of the Szent István University investigates the motion of the human knee in the case of squatting. In the analysis of the previously mentioned motion the emphasis is laid on the kinematical properties, which is approximated by experimental and numerical ways. Primarily the sliding and rolling properties of the human condyles are examined, especially I in those domains where pure rolling, rolling and sliding jointly, and pure sliding may occur. Since only the two extremities are well known in the theoretical and applied mechanics, this paper wishes to furnish further information to the subject. On the other hand, in order to determine special additional features the global experimental investigations of the knee are also crucial. These results can be essential for further investigations of the phenomena of the combination of rolling and sliding and to show a new path of creating prosthesis

Review of current knee biomechanical modeling techniques

In this paper we are going to present an essential modification of an existing analytical model. The model creation normally starts with a simplified, less complex analytical model, where the phenomena can be easily interpreted, checked and controlled. If this model is available and valid – with its certain simplifications – then as a following step, it can be either extended by taking into account earlier neglected factors or a similar but more advanced computational model has to be created in order to broaden the investigated factors. The accent will be set on a neglected factor, the moving center of gravity (COG), in this paper, and the obtained results will be compared with some external data from other authors

Effect of particle size on the surface properties and morphology of ground flax

Flax fibers were ground with a ball-mill and four fractions with different size ranges were collected by sieving. These were tested for water sorption, degree of polymerization (DP), copper number, hydroxyl number and analyzed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and inverse gas chromatography (IGC). Significant differences were found between the properties of the flax fiber and those of the ground versions, including fragmentation of fibers, increase of water sorption, copper number, hydroxyl number and surface O/C ratio, and decrease of DP, crystallite size and dispersive component of surface energy (gammasd). Some parameters depended on the particle size: O/C ratio and hydroxyl number had local maxima at 315-630 μm, while gammasd increased steadily with the decrease of particle size. These relationships were explained by fiber disintegration, destruction of waxy surface layer, exposure of cellulosic components, increase of surface area and crystalline imperfections

Prenatal development of the myenteric plexus in the human fetal small intestine

The enteric nervous system is large, complex and independent of the central nervous system. Its neuralcrest-derived precursors migrate along defined pathways to colonize the bowel. It has been established that signalling molecules produced by the developing neurons and the mesenchyma of the gut wall play a critical role in the development of the mammalian enteric nervous system. Recent studies have further characterized the roles of the different cellular and molecular elements that are critical for enteric ganglia formation. The application of modern neuroanatomical techniques revealed that the enteric nervous system contains a considerable number of neuronal subpopulations. Most of our knowledge concerning the functional features of the enteric neurons, e.g. chemical coding, neuronal connectivity and electrophysiological behaviour, was derived from studies of the guinea-pig small intestine. In light of the interspecies differences, comparison of the findings on different species is mandatory. Consequently, the investigation of human fetal material is necessary in order to estab-lish the basic rules of the development of the human enteric nervous system and to find the time relation between the morphological and functional maturation, thereby permitting an understanding of the causes of congenital malformation leading to misfunction of the gastrointestinal system

Electrocoagulation: an electrochemical process for water clarification

Electrocoagulation is a group of various procedures used for removing contaminants from water by electrochemically dissolving aluminum or iron. The contaminants of the solution may be incorporated in the in situ forming metal hydroxide flocs, which can be filtered as a precipitate or skimmed as a float. The main features of the procedure are highlighted on the example of cleaning of an oily waste-water. Design parameters of a 1 m3/h waste-water cleaning system are calculated from the results of small-scale experiments