Purchase decision-making support in the welding industry with the use of the k-means method

Podejmowanie decyzji w przedsiębiorstwie wiąże się często z wyborem najlepszego rozwiązania na podstawie wielu kryteriów opisujących analizowany problem. Z tego punktu widzenia można go nazwać wielokryterialnym problemem decyzyjnym. W artykule przedstawiono zastosowanie jednej z metod wspomagania decyzji – analizy skupień metodą k-średnich – w doborze materiałów dodatkowych do procesu spawania metodą SAW. Dokonano podziału na skupienia, uwzględniając dwa kryteria doboru ich początkowych centrów, porównano oba warianty, a na końcu scharakteryzowano szczegółowo grupy wyodrębnione za pomocą jednego z nich. Wybrane podejście do analizy skupień okazało się przydatne we wspomaganiu decyzji dotyczących zakupów w branży spawalniczej.Decision-making in enterprises is often connected with selecting the best solution on the basis of many criteria describing the analyzed problem. From this point of view, it can be called a multi–criterial decision–making problem. The article presents the use of a chosen clustering method – the k-means method – in the selection of materials for the SAW method process. Clusters were divided into two, based on the two different ways of choosing their initial centers. The two options were compared, and finally the clusters created on the basis of the chosen division were characterized in detail. The selected approach proved useful as decision-making support for purchasing materials in the welding industry

Selection of data mining method for multidimensional evaluation of the manufacturing process state

The article deals with the issues involved in evaluating the process state on the basis of many measures, including: process parameters, diagnostic signals and events occurring during the process. These measures as well as those measurements traditionally used in the evaluation of process capability, offer a relevant source of information about the manufacturing process and the authors attempted to ascertain the most suitable method, or group of methods, for achieving this. They present the main criteria for the categorization division of the methods of the manufacturing process state evaluation and, from those identified, distinguish the traditional from Data Mining methods. The authors then specify some basic requirements regarding the desired method or group of methods and focus on the classification problem. A division and classification of the methods is made and briefly described. Finally, the authors specify the criteria for their selection of the Data Mining method type as being the most appropriate for the evaluation of the manufacturing process state and, from within this type, offer the most suitable groups of methods. Some directions for further research are discussed at the end of the article

Application of expectation maximization method for purchase decision-making support in welding branch

The article presents a study of applying the proposed method of cluster analysis to support purchasing decisions in the welding industry. The authors analyze the usefulness of the non-hierarchical method, Expectation Maximization (EM), in the selection of material (212 combinations of flux and wire melt) for the SAW (Submerged Arc Welding) method process. The proposed approach to cluster analysis is proved as useful in supporting purchase decisions

Applying the time-lapse imaging technique for the studies of stem gravitropic kinetics in the changed gravimorphic conditions

White willow (Salix alba L.) dormant shoots were collected in March and cut into 30 cm segments. The basal ends were placed in containers with sand and kept in dispersed sunlight and the halogen light after dark. To induce the gravimorphic reaction the segments were oriented at the angle of 30 degrees with respect to horizontal line (stage I). After two weeks of culture the segments were turned at the angle of 150 degrees in such a way that the segments were in horizontal position and the newly formed lateral shoots were oriented according to the gravity vector (fig. 1). They were kept in such position for another 2 weeks (stage II). The growth kinetics of newly formed shoots was studied using time lapse technique. It was found that during stage I the most intensive development of lateral buds growth occurred on the upper side at apical part of the shoot segment. During stage II, the newly formed shoots started to reorient opposite to the gravity vector. The latateral shoots close to the apical end responded faster as compared to the shoots located at farther distances. The site of gravitropic response during 2−week−long experiment was moving and located always below apical part of the lateral shoot in the non−lignified zone. Microscopic observations of the newly formed lateral shoots revealed formation of secondary xylem typical for willow and in some regions the structure newly formed xylem was similar to that of tension wood. The possibility of application of 3D digital Image Correlation method for the studies of growth trajectory was tested in the preliminary experiment performed on the seedlings of Cucumis sativus (fig. 2). The preliminary results (fig. 3) indicate that the method could be applied also for the of growth trajectory of woody plants

A hybrid system for simultaneous measurements of temperature and displacement distributions of engineering objects

W artykule przedstawiono hybrydową eksperymentalno-numeryczną technikę przeznaczoną do pomiaru oraz monitorowania struktur inżynierskich. Technika bazuje na innowacyjnym połączeniu termowizji z metodą cyfrowej korelacji obrazu w wersjach 2D i 3D. Zaprezentowany system umożliwia jednoczesny pomiar i monitorowanie zmian obciążenia termicznego (rozkładu temperatur) oraz przemieszczeń w płaszczyźnie badanego obiektu w całym polu widzenia czujnika (do 2,5 m x 2,5 m). Przedstawiono zastosowania systemu na przykładzie monitorowania zmian pól przemieszczeń u(x,y) i v(x,y) i temperatury T(x,y) na powierzchni modelowej próbki (płyty z karbem) oraz w trakcie badań nowych materiałów izolacyjnych stosowanych w budownictwie.The techniques used for displacement/strain measurements and defect detection in civil engineering structures are based on a variety of physical phenomena, among which mechanical, optical, electrical and ultrasound methods prevail. Each of these methods has its unique properties. In the case of complex structures and structures exposed to a variety of environmental conditions the information gained from a combination of methods provides the best results. The most required measurands during structural health monitoring are in-plane and out-plane displacements which are directly related to strains. The best fitted method in this case is the digital image correlation method which may be used for global and local health monitoring of different structures. Also in many cases passive and active thermography is used for identification of thermal load distribution as well as assessing and monitoring the health of engineering structures, however the results are often difficult for quantitative interpretation. In the paper we focus on a novel concept of the hybrid experimental-numerical method for measurement and monitoring of engineering structures. The technique is based on an innovative combination of thermovision with 2D and 3D digital image correlation methods. The system presented enables simultaneous measurement and monitoring of thermal load (temperature distribution) and in-plane displacements of an object in a full-field of view (up to 2,5 m x 2,5 m). The system functionality was demonstrated on an example of monitoring the displacement fields u(x,y) and v(x,y) as well as the temperature T(x,y) on the surface of a model sample with a notch and during investigations of novel insulating materials used in building engineering

Zastosowanie optycznych czujników przemieszczeń, wykorzystujących techniki interferometryczne, do kontroli i monitoringu konstrukcji inżynierskich

Inspection and monitoring of engineering structures require simple, fast and remote acquisition, processing and visualization of relevant measuring data. Systems which utilize all above requirements are fundamental for Structural Health Monitoring (SHM). All necessary information should refer to safety threshold and sent to end user, who can accurately assess the health of an object in short time and schedule necessary actions in order to prevent accidences. The paper presents the novel approach to optical displacements sensors. Authors describe low-cost in-plane displacement and strain sensors for monitoring in crucial regions of big civil engineering structures (square millimeters area around welds, joints etc.) by means of two interferometry techniques: Grating Interferometry (GI) and Digital Speckle Pattern Interferometry (DSPI). In principle both of the methods applied have their specific requirements and can be used as complementary ones. GI requires specimen grating attached to the flat surface of an object under test, but it is the unique technique which may provide the information about fatigue process and increased residual stresses. DSPI works with a rough object surface, but due to differential measurements cannot be simply used for long time monitoring but to explore the actual behavior of a structure. We present both sensors working separately, but also we propose the technique which enables usage of the DSPI for long time or periodic monitoring by combining it in one sensor with GI in order to increase number of possible applications of the system. Both sensors can be manufactured by using low - cost replication technologies. The paper presents their mechanical and optical design along with laboratory tests of their main modules which are the sensor heads in the form of monolithic (plastic) and cavity waveguides. Finally, the exemplary applications of sensors in laboratory tests and on exemplary frame truss structure are presented and assessed.Kontrola i monitoring konstrukcji inżynierskich wymaga prostej, szybkiej i zdalnej akwizycji oraz przetwarzania i wizualizacji danych pomiarowych. Systemy spełniające powyższe wymagania są niezbędne do monitorowania stanu technicznego konstrukcji (ang. Structural Health Monitoring - SHM). Dane uzyskiwane przez systemy monitoringu powinny odnosić się do założonych poziomów bezpieczeństwa i być wysłane do końcowego użytkownika, aby mógł on w krótkim czasie ocenić stan obiektu i zaplanować niezbędne działania celem zapobiegnięcia wypadkom. W artykule zaprezentowano nowe podejście do optycznych czujników przemieszczeń. Opisano niskokosztową głowicę interferometryczną wykorzystującą metodę interferometrii siatkowej i cyfrowej interferometrii plamkowej do pomiarów przemieszczenia i odkształcenia w płaszczyźnie. Przedstawiono jej zastosowanie w monitoringu newralgicznych punktów wielkogabarytowych konstrukcji inżynierskich (regiony wokół spawów, połączeń itp.). W pracy przedstawiono również projekt mechaniczny i optyczny czujników oraz testy laboratoryjne ich głównych modułów (falowodowych głowic pomiarowych). Na koniec przedstawiono aplikację opracowanych czujników na przykładowej konstrukcji kratownicowej

The studies of the illumination/detection module in Integrated Microinterferometric Extensometer

In this paper the novel, miniaturized full-field optical extensometer for full-field in-plane displacement measurement is presented. It consists of two modules: illumination/detection module (IDM) and Measurement Head (MH) based on grating interferometry. In the paper we study the performance of IDM, which provides the object illumination beam and captures the output interferogram. The characterization of VCSEL comprises determination of polarization state, intensity distribution, coherence path length and shape of the wavefront after being collimated by beam forming optics. The detector matrix has been tested mainly in respect of the signal to noise ratio at various exposure times and its spatial uniformity of sensitivity.</p

Monitoring of civil engineering structures using Digital Image Correlation technique

The Digital Image Correlation (DIC) technique enables full field, noncontact measurements of displacements and strains of a wide variety of objects. An adaptation of the DIC technique for monitoring of civil-engineering structures is presented in the paper. A general concept of the complex, automatic monitoring system, in which the DIC sensor plays an important role is described. Some new software features, which aim to facilitate outdoor measurements and speed up the correlation analysis, is also introduced. As an example of application, measurements of a railway bridge in Nieporet (Poland) are presented. The experimental results are compared with displacements of a FEM model of the bridge