The hard life of air bubbles crossing a fluid/fluid interface

We investigate the dynamics of isolated air bubbles crossing the horizontal interface separating two Newtonian immiscible liquids initially at rest by means of experiments and DNS. High-speed video imaging is used to obtain a detailed evolution of the various interfaces involved in the system. The size of the bubbles and the viscosity contrast between the two liquids are varied by more than one and four orders of magnitude, respectively, making it possible to obtain bubble shapes ranging from spherical to toroidal. A variety of flow regimes is observed, including that of small bubbles remaining trapped at the fluid–fluid interface in a film-drainage configuration. In most cases, the bubble succeeds in crossing the interface without being stopped near its undisturbed position and, during a certain period of time, tows a significant column of lower fluid which sometimes exhibits a complex dynamics as it lengthens in the upper fluid. Direct numerical simulations of several selected experimental situations are performed with a code employing a volume-of-fluid type formulation of the incompressible Navier–Stokes equations. Comparisons between experimental and numerical results confirm the reliability of the computational approach in most situations but also points out the need for improvements to capture some subtle but important physical processes, most notably those related to film drainage. Influence of the physical parameters highlighted by experiments and computations, especially that of the density and viscosity contrasts between the two fluids and of the various interfacial tensions, is discussed and analysed in the light of simple models

Design of a universal robot controller

The paper deals with a general purpose industrial robot controller. Due to the modules of the system is universal. It can be connected to several types of robots, even to CNC, turning-mill or other machines. It was connected to an Adept Scara robot successfully,experimental results will be presented. The basic element of the system is the EMC2 open source robot controller program, which runs in a realtime linux kernel. A PCI card creates the high speed connection between the EMC2 and the machine. DC servo amplifier, digital input and output module, teach pendant, and power electronics designed for the system. The system is RT-middleware (Robotics Technology Middleware)compatible. The RT-middleware is a common robot control platform, which can easily connect different robots to the same network for a common work

Improvement of High Strength Automotive Steels Wettability Properties Using CO2 Laser Surface Treatment

As a result of stricter environmental and safety standards, vehicle manufacturers have to reduce the weight of the vehicles, because 10% weight loss cause 8-10% reduction of fuel consumption. To reduce car’s weight and increase safety, vehicle manufacturers use high-strength steels. Further weight reduction can be achieved by using corresponding bonding technology (soldering, sticking) and optimizing these technologies can increase the strength of the joints. According to literature research, the improvement of interface properties has a large effect on bonding technologies. In order to improve interface properties, we can use multiple surface treatments. In our research we investigate the effects of CO2 laser surface treatment on high strength steels, because CO2 lasers are often used in the vehicle industry. In order to detect the effect of surface treatment, we investigate the wettability of the treated and untreated steels. In our research we measure the surface tension of treated and untreated steels. Our main goal is to improve wettability properties thus the bonding technology. In our research we used DP 600 high strength steel sheet with the thickness of 1 mm. We cut the steel sheet to 25mm wide and 55mm long workpieces. Before the surface treatment, the workpieces had to be cleaned and degreased using methanol. We searched for parameters that do not cause any visible changes on the surfaces. Among the parameters of the treatment we were able to change the output power of the laser. We used contact angle measurement to examine the wettability

A Greenman Agro termésnövelő készítmény hatása néhány szőlőfajta gyökeresedésére

Egy szőlőszaporítóanyag termelő üzem sikeres tevékenységének legfontosabb záloga, hogy egységnyi területen mennyi gyökeres szaporítóanyagot tud előállítani. Ez a szaktudáson és a gyökereztetés feltételein múlik, nem is beszélve a szaporító alapanyag minőségétől. Hagyományosan szintetikus gyökereztető hormonokkal lehet növelni az eredést, az utóbbi években azonban megjelentek olyan biostímulátor anyagok, melyek a gyökérképződésen túl a növények fejlődésére, ellenálló képességére is pozitívan hatnak. Ezzel a kihozatal javul, a gyökeres szaporítóanyag pedig fejlettebb lesz. Kísérletünkben a Greenman Agro biostimulátort alkalmaztuk a dugványok beáztatására, tápoldatozásra és permetezésre. Az összes fajta esetében a kezelt növények szignifikánsan növelték a hajtások hosszát, viszont a pozítív hatás nem minden fajtánál volt megfigyelhető. A talaj a domborzat nagymértékben módosította az eredményeket, ezért célszerű lenne a kísérletet tenyészedényben megismételni

Industrial robotics for ERP controlled smart factories

At product manufacturing the time-to-market factor, the profitability and the delivered value define the success of an enterprise. The increasing number of modules in Enterprise Resource Planning (ERP) programs is a facing problem, when there is a margin between the manufacturing cells and the ERP. Nowadays, the connection between the industrial machines and the ERP is an important requirement especially at automated warehouses and smart factories. Other concerns at manufacturing are the maintenance schedules of the machines, and flexible and easy reconfiguration of the production lines or the production cells. Information technology provides solutions and software environments to implement complex production supervisor ERPs at smart factories. At a production line or an automated warehouse several technical parameters and information can influence the planning of the resources at the enterprise, like maintenance, machine error, stockpile, product ID, defective product ratios, etc. When there is machine maintenance, the company needs to order the service parts, as well as schedule the service time and the stop of the production line. In case of a machine error, the system can estimate the length of the service time from error messages, and reorganize orders, transportation, or even maintenance schedules of other machines. Our plug and play type robot and industrial automation controller project gives a solution for these hardware demanding needs

Axiális átömlésű áramlástechnikai forgógépek korszerű tervezési módszerének kidolgozása a háromdimenziós áramlás figyelembevételével, szimulációs és kísérleti eszközök alkalmazásával = Elaboration of a novel methodology for design of axial flow turbomachinery with consideration of three-dimensional flow, with application of simulation and experimental tools

Az OTKA projekt keretében mérnöki támpontokat alapoztunk meg fokozott fajlagos teljesítményű - sugár mentén növekvő cirkulációra méretezett - axiális átömlésű forgógépek tervezése során a lapátnyilazás hatásainak figyelembevételére, hatásfokjavítás és széles leválásmentes üzemállapot-tartomány elérése érdekében. A támpontokat a lapátozásra jellemző, súrlódás által befolyásolt háromdimenziós áramlás jellegzetességeinek analitikus, numerikus áramlástani és kísérleti vizsgálata alapján fogalmaztuk meg. A támpontok alapján a lapátnyilazás hatásait is megbízhatóan figyelembe vevő, szisztematikus, numerikus áramlástani eszközökön alapuló lapát-optimalizáció valósítható meg. | Within the framework of the OTKA project, engineering guidelines have been established for consideration of effects of blade sweep in design of axial flow turbomachines of high specific performance ? obtained by means of spanwise increasing design blade circulation ?, in order to improve the efficiency and to extend the stall-free operational range. The guidelines have been formulated on the basis of analytical, Computational Fluid Dynamics (CFD) and experimental studies on the features of three-dimensional viscous flow characterising the blades. Based on these guidelines, a systematic, CFD-aided blade optimisation methodology can be developed that takes the effects of blade sweep reliably into account

Mobile Robot Performance Analysis for Indoor Robotics

In the last few years the market of robotics has significantly changed and the growing sector of service robotics requires new considerations in civil engineering. This paper investigates different room and furniture arrangements in the view of mobile robot navigation requirements. The described method provides robot motion and path planning cost functions for different furniture arrangements and floor maps. During mobile robot path planning ISO 7176-10:2008 and ISO 7176-5:2008 (electrically powered wheelchair) compatible buildings were considered to find the optimal solutions over the minimal standardized requirements. The proposed method can provide efficient results regarding navigation error, time and power consumption