Solid State Phenomena Vol. 199

Abstract: This paper presents a new distance calculation circuit (DCC) that in artificial neural networks is used to calculate distances between vectors of signals. The proposed circuit is a digital, fully parallel and asynchronous solution. The complexity of the circuit strongly depends on the type of the distance measure. Considering two popular measures i.e. the Euclidean (L2) and the Manhattan (L1) one, it is shown that in the L2 case the number of transistors is even ten times larger than in the L1 case. Investigations carried out on the system level show that the L1 measure is a good estimate of the L2 one. For the L1 measure, for an example case of 4 inputs, for 10 bits of resolution of the signals, the number of transistors is equal to c. 2500. As transistors of minimum sizes can be used, the chip area of a single DCC, if realized in the CMOS 180 nm technology, is less than 0.015 mm².

Abstract: One of the results of the dynamic progress in the field of industrial and applied computer science and mechatronics is the growing interest in usage of the machine vision algorithms and systems. One of such areas of applications is the positioning of the workpieces on the CNC machines based on the image analysis, allowing also the visualization of the workpiece observed from an arbitrary viewpoint located between two or more cameras. Such virtual camera can be effectively implemented using Image Based Rendering technology [ but one of its limitations is the necessity of using the depth maps, which have to be acquired for each reference image. It can be done using the additional fringe patterns projector, similarly as in typical 3D scanning systems or using some other approaches e.g. stereovision. Nevertheless, the quality of images obtained using the typical IBR method is limited by the missing pixels (holes), which should be filled using splatting algorithm, which typically cause the noticeable blurring of obtained image. The solution proposed and discussed in this paper is based on the sub-pixel IBR method with additional filtering and interpolation of the points acquired from the reference cameras allowing increasing the quality of the final images obtained as the visualization of the positioned workpieces.

Abstract: The laboratory and field investigations of the several automatic gravimeters Scintrex CG_5 with a quartz elastic system used for the determining of gravity acceleration were performed. Research on characteristics of four gravimeters includes a five-year period. The data consists of gravimetric observations at a laboratory, on the gravimetric testline and at the points of the Lithuanian gravimetric network. The evaluation of the phenomena of the spring systems of the gravimeters was made. The stress on the estimation of the zero drift at a laboratory and field investigations was done. It was detected that zero drift does not exceed 500 μGal per day with a diapason of 200 μGal. The zero drifts per hour do not exceed 25 μGal, mostly they are under 10 μGal. According to the annual calibration results the character of the changes of the linear scale coefficients of the gravimeters were analysed too. The calibration base of 270 km length in Lithuania where the difference of the gravity acceleration of the end points is 201 mGal was used for investigations. The research showed that the biggest deviation from the unit of the linear scale coefficients does not exceed 0.013. It was noted, that the values of the linear scale coefficients of the gravimeters have a tendency to decrease. Also was noted, that the values of the linear scale coefficients have a tendency to decrease in the period between field works, and to increase - in the field works period. So the calibration of the gravimeters should be carried out before and after the field works. Based on measurements carried out during development of the Lithuanian gravimetric network, which consists of 686 gravimetric points, accuracy of gravity acceleration increments was assessed. The comparison of the observations results against the results, obtained by the LaCoste and Romberg gravimeters with metal elastic system, is presented too. The total number of common points is 51. It was stated, that the differences of the gravity accelerations measured by the different types of gravimeters at gravimetric points do not differ more than 10 μGal, therefore maximum difference of 25 μGal was received. The standard deviations of the gravity accelerations of the gravimetric points do not exceed 7 μGal. Such results show the good performance of the SCINTREX CG_5 gravimeters.

Abstract: The paper presents the possibilities of a hybrid vision method based on simultaneous analysis of infrared and vision images for surface inspection of hot aluminium in a manufacturing process. The system consists of a NIR/SWIR camera and a high resolution visual camera, and a computer based image analysis system. The simultaneous analysis of infrared and vision images will enable surface inspection for detecting defects in temperature range from 200°C to 600°C. Thermal images present temperature distribution on the surface, and contain information about the manufacturing process. The analysis of thermograms enables to find areas of temperature irregularity caused by increased friction loads, as well as areas of inhomogeneous emissivity caused by surface defects. Furthermore, information captured by the vision camera is used to detect surface defects. The software developed enables the overlaying of images. The proposed simultaneous thermovision and vision imaging can be applied in industry for in-line monitoring of aluminium extrusion processes.

Abstract: Reverse engineering [ is a field of technology which has been under rapid development for several recent years. Optic scanners are basic devices used as reverse engineering tools. Point cloud describes the shape of a scanned object. Automatic turntable is a device which enables a scanning process from different viewing angles. In the paper, the algorithm is described which has been used for determination of rotation axis of a turntable. The obtained axis constitutes the base for an aggregation of particular point clouds into single resultant common cloud describing the shape of the scanned object. Usability of this algorithm for precise scanning of mechanical parts was validated, precision of shape replication was also evaluated.

Abstract: The paper presents the methodological approach to development of curves by selection of driving parameters with the application of the method to designing and reproduction of aircraft surfaces on the examples of both newly designed aircrafts and the ones that are already in service. The major assumptions are outlined that are necessary to develop the mathematical model of driving curves and surfaces, these assumptions served as the basis to draw up the relevant algorithms and to convert them to routines of the GRIP (Graphics Interactive Programming) language that is a part of the CAD/CAM/CAE Unigraphics system. These algorithms include the newly developed tool dedicated to design aircraft components and provided with inputs to the multi-criteria synthesis of the aerodynamic profiles of aircrafts. The study comprises also the assumptions to the newly developed algorithms dedicated to modelling of components incorporated into aircraft structures, these algorithms have been successfully implemented by the author.

Abstract: The purpose of this research is to detect the atomic spectrum of cesium using laser-induced breakdown spectroscopy (LIBS). In this study, pollucite ((Cs,Na)(AlSi₂)O₆.nH₂O) was used as a test sample for the LIBS measurement. LIBS is a useful tool for the determination of the elemental composition of various materials and it does not require any preprocessing step. The Nd:YAG laser was operated at 1064 nm to generate a 50-mJ Q-switched pulse with a width of 8 ns (full width at half maximum, FWHM). The breakdown emissions were dispersed by a grating with a groove density of 1200 lines/mm and the resulting electrical signal was recorded using a streak camera. The plasma intensity was optimized with respect to the background. Spectral measurements were carried out after an appropriate delay time to allow for the decay of the continuum radiation. In the experiments, 100 laser shots were used to record data for each spectrum in ambient air. The results of the experiments showed that the atomic signals corresponding to pollucite were obtained easily by LIBS measurements. Thus, spectrum peaks due to cesium, sodium, aluminum, and silicon are observed. In particular, the characteristics of the cesium spectrum play an important role in establishing the LIBS system for environmental monitoring, which may be used to detect radioactive elements emitted from nuclear plants.

Abstract: The article presents the method for the determination of energy characteristics of the pneumatic cannon by means of high speed imaging. The gun tested is a device enabling bird collision endurance tests to be conducted for the structural element of aircrafts. In the tested 250 [m system, the projectiles were thrown in the plastic sabot damaged in the muzzle of the gun. The tests were conducted in the speed ranging between 100 300 m/s for 0.9 and 3.6 [k projectiles. The objective of the tests was to determine the characteristics of the projectile outlet velocity in the feed pressure function. The measurement stand was equipped with the Phantom V310 high speed camera The speed measurement was conducted with the use of the digital image analysis in which commercial TEMA Motion software was used. Results were corrected so that the parallax error could be eliminated. Because of the cylindrical shape of the projectile, the parallax error for the front at the back of the projectile varied, which required two correction coefficients to be applied. The speed was calculated by the averaging of the results for the front and the back of the projectile. For the recordings, in which the remaining of the sabot prevented the accurate arrangement of measurement points, a simplified speed measurement method was used. Measurement uncertainty sources are also described (shift of the projectile at the time of the exposure, measurement point positioning error). The influence of the parallax error on the measurement result and the cannon energy characteristics obtained are presented. The obtained characteristics enable proper selection of feed pressure allowing for the procurement of the outlet velocity suitable for the tests conducted.

Abstract: In the present work, different copper ring samples geometries with a small aspect ratio of 0.5 or 1 were subjected to an experimental study under electromagnetic expanding ring test conditions. The experimental multiple ring tests were performed under similar loading conditions, that is, the applied maximum expansion velocities covered a range from 128 to 147 m/s (7.4 10³ s^-1) for all ring samples geometries, with the exception of rings with a cross section of 1 mm x 0.5 mm. For these rings, the averaged maximum expansion velocity was higher and equal to 195 m/s (1.2 10⁴ s^-1). The results of experimental investigations revealed a minor influence of the applied cross section sizes on ductility of copper rings, whereas its fragmentation seems to be dependent on a ring cross section area.

Abstract: In this experimental study, maximum torsion shear stresses occurring on the hallow aluminum shaft under various small torsion loads were measured with strain gauge, data acquisition cards and computer. Special software was developed to measure maximum strain and stress on the thin aluminum hollow shaft. Stress values occurring on the aluminum hallow shaft under various small loads were measured with strain gauge and those strain values were transmitted to computer directly with data acquisition cards. Using the strain, the load and other constant values of the material (Torsion stress, outside and inside diameters of shaft, length of shaft, shear stress modulus, applied torque loads, twist angle of shaft etc) the stress values occurring on the hallow shaft are calculated by computer program and the stress-strain graph is drawn on the computer screen automatically [Refer to table1 Fig. 2,3,4 ,5 and . In this experimental study, the theoretical knowledge given in the books and experiment results obtained under laboratory conditions were compared with each other. The obtained results were almost same. Similar experimental application could be used for real applications in car industry and mobile machines [.